DYNAMICS OF RAILWAY FREIGHT VEHICLES

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This paper summarises the historical development of railway freight vehicles and how vehicle designers have tackled the difficult challenges of producing running gear which can accommodate the very high tare to laden mass of typical freight wagons whilst maintaining stable running at the maximum required speed and good curving performance. The most common current freight bogies are described in detail and recent improvements in techniques used to simulate the dynamic behaviour of railway vehicles are summarised and examples of how these have been used to improve freight vehicle dynamic behaviour are included. A number of recent developments and innovative components and sub systems are outlined and finally two new developments are presented in more detail: the LEILA bogie and the SUSTRAIL bogie.

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Iwnicki S.D. 1 , Stichel S. 2 , Orlova A. 3 , Hecht M. 4

Introduction

From their inception railways have been predominant in the carriage of bulk goods and railway wagons have been designed to allow this to be effected efficiently on different types of railway infrastructure. In more recent times with changes in industrial needs and competition from road and air transport railways have carried an ever declining share of freight. Although there is some evidence in some countries that this trend has started to change recently due to road congestion there is still not yet a widespread evidence of a major modal shift from road to rail which politicians have indicated is desirable. For example the European Transport White paper 2011 [1] sets a target for modal shift of 30% by 2030 and 50% by 2050 from road freight to other modes such as rail or waterborne transport for distances over 300 km.

The barriers to this increased modal shift from road to rail seem to be largely due to the requirements from modern shippers for shorter end-to-end times but even more the demand is for high reliability of service and for additional features such as tracking and tracing of shipments, security and temperature control. As Hecht [2] points out the lower speeds for rail freight compared with passenger services are not mainly related to lower vehicle speed capability but are more due to the fact that freight trains often travel on lower speed lines or are held for passenger traffic to pass and due to complex and lengthy shunting and handling operations and motive power and crew changes.

Nevertheless if freight vehicle speeds and acceleration and braking capabilities could allow them to be fully integrated with passenger traffic this would bring a step change in end to end freight train speeds as well as overall system capacity. A key factor in obtaining this increased speed is to ensure that the dynamic performance of freight vehicles can allow safe and reliable operation on track with different levels of irregularities and support conditions. Running gear has evolved with the experience of operation on different railways and more recently the use of computer simulation tools and several standardised designs are now ubiquitous. Several research projects and teams have recently been trying to advance from this position using innovative designs adapted from passenger vehicles or using other novel techniques. The use of computer simulations is now established for design of running gear and is also becoming accepted as part of the vehicle acceptance processes in many countries.

Early developments of freight wagons

Background

Designers of freight vehicle running gear face many challenges but not least of these is the fact that the ratio of the laden to tare mass of a freight vehicle can be as much as 5:1 compared with a more manageable 1.5:1 for typical passenger vehicles. This effectively means that the suspension system has to be designed for two different vehicles (and every stage in between). A number of clever designs have evolved over the years and the most successful of these are now summarised.

UIC double link

Freight wagons with link type suspensions have existed for more than 100 years, as can be seen in figure 1, and the link suspension is probably still the most common suspension type for two axle freight wagons in Europe today. As early as 1890 the principle of the link suspension was defined as a standard. A review of freight wagons with link suspension can be found in [3]. After World War II the UIC double link suspension was defined as a standard [5]. In the beginning of the 1980s a number of improvements were made. The axle load was increased to 22.5 tonnes and the parabolic leaf spring was introduced as standard component [6], [7]. The UIC double link suspension in figure 2 mainly consists of three parts: Leaf springs, links and axle guards. The vehicle is connected to the parabolic or leaf spring by double links. The leaf spring rests on the axle box. This arrangement allows the axle box to move in both the longitudinal and lateral direction relative to the wagon body. The axle guard restricts the horizontal motion of the axle box. The principle of the suspension is that of a pendulum. In the longitudinal direction the suspension links are inclined, whereas in the lateral direction they are in a vertical plane when the vehicle body is in nominal position [1], [8], [9], [10]. The characteristics of the double-link suspension are quite complex. The main components are shown in Figure 3. One of the main advantages of the link running gear is that it is simple, robust and cheap and also takes up little space in both lateral and vertical directions. Both stiffness and damping are provided by one system and are load dependent. The quasistatic curving performance of the single axle running gear with link suspension is good. For a typical two-axle freight wagon with a wheelbase of 9m on dry rails good steering performance down to 300 m curve radius can be achieved [10].

The running behaviour of two-axle freight wagons with link suspension can be rather poor mainly due to vehicle hunting. The amount of damping provided in the horizontal plane is often not sufficient. Additionally the characteristics of the suspension change during the life of the vehicle, due to suspension wear, and with the running conditions [10]. The link suspension takes quite a lot of longitudinal space and is a poor isolator for sound and vibration.

Link suspension bogies

The leaf spring and link suspension of the single-axle running gear has also been used on bogies since about 1925 [1]. More recently it has been standardised with for example bogie type 931 (figure 4), developed in the 1950s by Deutsche Bahn with a wheelbase of 2000 mm and a wheel diameter of 1000 mm. This bogie was developed to run at 100 km/h with an axle load of 20 t and was the first bogie standardised by UIC [6], [7]. In the beginning of the 1980s DB bogie type 665 was introduced with new features like parabolic leaf springs, 22.5 t permissible axle load and shorter links as shown in figure 5 [7]. The bogie frame is a welded steel design but in some places forged components are used. The frame is connected to parabolic or trapezoidal leaf springs, that rest on the axlebox, being connected by swing links. Nominally the suspension links are positioned in a longitudinal vertical plane and inclined in this plane. During vehicle operation the links swing in that plane and also laterally [1], [6], [7], [11]. A spherical centre-pivot and two side bearers connect the bogie frame and the wagon body. The side bearers can be either rigid or vertically suspended and have three functions:

 to act as static support for the carbody.  to act as roll stiffness.  to provide friction damping between carbody and bogie The quasistatic curving performance of a bogie with link suspension is generally very good due to:

 the short wheelset distance in the bogie of 1.8 m.  the soft longitudinal primary suspension.

The Y25 Standard Bogie

Most railway vehicles have bogies or trucks which allow longer vehicles supported on two bogies while still keeping attack angles between wheels and rail in curves to reasonable levels. This arrangement also allows two stages of suspension with the 'primary' suspension between wheelset and bogie and secondary suspension between bogie and coach or wagon body. The primary suspension can isolate the bogie from short wavelength irregularities while the secondary suspension deals with the longer wavelength, lower frequency excitations.

As previously mentioned, a specific challenge for designers of freight vehicle running gear is the large difference between tare and laden vehicle mass. In the Y25 bogie progressive damping with vertical load is effected by the use of 'Lenoir links' which take part of the vertical load through an angled link and a pusher onto a vertical friction surface. This gives a level of damping which is broadly proportional to the vehicle mass. The Y25 bogie design originated in France in 1948 and was standardised by the ORE steering committee in 1967. It is shown in figure 6.

Figure 6: A Y25 type bogie

The design has been hugely successful and Y25 type bogies are the most predominant freight bogie in Europe.

'three-piece' Freight Bogies

The three-piece bogies were first developed in 1930s and seemed to originate simultaneously in the USA (Barber bogie) and the Soviet Union (Hanin bogie). Now the three-piece bogie and its more sophisticated descendents are the most common suspension for freight wagons across North and South Americas, CIS countries, China, Africa, India and Australia. Maximum axle loads range between 7 and 36 t. The most common standards for three-piece bogies are AAR [13] for 1435 mm gauge and GOST [14] for 1520 mm gauge. A review of three-piece bogies can be found in [15].

The Russian model 18-100 bogie shown in figure 7 is a good example of an early type of three-piece bogie. The term 'three-piece' refers to the design of the bogie frame which consists of three interconnected parts: two side frames and one bolster. The frame parts are usually cast.

The bogie is equipped with central suspension between the side frames and the bolster that consists of a set of springs and wedge friction dampers working in vertical and lateral direction and keeping the frame square. The side frames with their flat surfaces rest on the axle-boxes (or bearing adapters). The size of the opening in the side frame provides clearances in longitudinal and lateral direction within which the axle-box moves resisted by dry friction forces. The car body rests on the flat center bowl, its roll motion relative to the bolster is limited by side bearers which are usually stiff vertical stops including clearance when the wagon body is in the central position. The three-piece bogie is a very robust design with the advantage of being low cost in production, operation and repair. The following items are considered as disadvantages of traditional three-piece bogie and attempts have been made to address these in its further developments [15], [16], [17]:

 Limited critical speed of the empty wagon )with sway oscillation of car body being the major loss of stability mode);  Wheel flange contact in curves produced by warping between side frames and bolster;  Side frames adding to the unsprung mass and thus increasing track impact on short wavelength irregularities;  Deterioration of ride performance with wear of friction wedges and other friction surfaces.

Computer simulation

Computer simulation of freight vehicles is not at all as common as for passenger vehicles. Since many of the European freight vehicles are standardized very little new development has been carried out and the manufacturers do in general not perform a simulation analysis of the running behaviour of freight wagon. However, in several research groups at universities and research institutes and at some consulting companies computer simulation of freight vehicles is now performed.

Since manufacturers do not usually build simulation models of freight vehicles themselves one of the main challenges in modelling a freight wagon is to obtain all the input parameters required. Another aspect is that most suspension elements are strongly non-linear and in many cases even mathematically non-smooth. This makes it very difficult to build up simulation models that provide good results compared to measurement results. Some of the phenomena observed during simulation of freight vehicles will be discussed below.

Further, as described in Section 3.1, the characteristics of the suspension elements can vary during operation due to wear or environmental effects such as for example surface contamination changing the friction coefficient in sliding surfaces.

The main purpose of simulation studies of freight vehicles is very often a stability analysis (see Section 3.2) or an investigation of the curving behaviour of the freight wagon (see Section 3.3). Since the axle loads of freight wagons are usually high, the investigation of wheel or rail wear and rolling contact fatigue is often the primary reason for a simulation study in curves.

Suspension components

The suspension in most freight vehicles relies on friction damping. Friction elements are low cost, require little maintenance and are usually load dependent. This means that the level of friction damping changes with axle load, an important feature in freight wagons due to the high tare to laden ratio already mentioned. Surveys of modelling of friction components in freight wagon can be found for example in [18]- [22]. Papers [18] and [19] are general reviews of rail vehicle suspension components, while [20] is focused on freight vehicles and also discusses issues such as stability and curving of freight vehicles. Papers [21] and [22] are focussed on modelling friction wedges of three-piece bogies. Also in the proceedings from the Euromech 500 colloquium [23] many valuable contributions on the topic of non-smooth suspension elements can be found. Various arrangements of suspension elements to simulate vehicle suspensions are documented in [24], [25].

Friction damping

In most freight vehicle simulation models friction is modelled as dry Coulomb friction, where the friction force is proportional to the normal load. The friction coefficient is assumed to be constant, see force-deflection curve in figure 8, left. The disadvantage of the Coulomb model is that it is non-smooth, i.e. multi-valued and non-differentiable. Another way to model friction is with a linear spring in series with a friction slider as in figure 9 with the resulting force-displacement characteristic in figure 8, right. Since most friction damper arrangements have a finite flexibility, such models could also be regarded as more realistic. Note, however that the model with a spring in series is still non-smooth. To avoid the difficulties mentioned above regularization methods are often applied, see for example [26], [27] and [28]. Piotrowski developed a non-smooth rheological model [29], [30], which employs the notion of the differential succession involving a contingent derivative of the non- smooth, multi-valued characteristics of Coulomb friction. Tan and Rogers [31] proposed equivalent viscous damping models to avoid the numerical problems of Coulomb friction. They claim that this substitution works very well for cases where sliding motions predominate.

In many running gear arrangements two-dimensional friction elements are needed, e.g. in the Y25 and in the three-piece bogie. In these designs motions in two directions tangential to the friction surfaces are possible. Two-dimensional Coulomb friction models can be found e.g. in [32], [33].

Another phenomenon that is important to take into account is stochastic excitations that smooth the dry friction damping. Also mid frequency excitation generated in the wheel rail contact - often called dither - can smoothen dry friction and therefore have a significant influence on the simulation results, see for example [30], [33].

True and Asmund [33] investigated the effects of dry friction in the suspension of a simple freight vehicle. They used a relatively simple model of dry friction and found that the stable behaviour for the system with friction exhibited a laterally oscillating motion which makes the system sensitive to external periodic forcing.

Wagons with link suspension

Basic model of leaf spring and link suspension

Leaf springs are often used as vertical suspension. In multibody simulation models they are usually regarded as rigid in both the longitudinal and lateral directions. For dynamic displacements around a static equilibrium position leaf springs are characterized by a relatively high stiffness for small displacements and a significantly lower stiffness for larger displacement, (figure 10). Leaf springs are described in the ORE reports [34], [35]. Since link suspensions show very similar characteristics they are often modelled in a similar way to leaf springs, at least for the lateral link behaviour. The initial higher stiffness k 1 in leaf springs is caused by friction, i.e. the leaves of a leaf spring stick together for small displacements and start to slide on each other for larger displacements. In the same way the link rolls in the end bearing as long as there is no sliding in the contact area. The lower stiffness k 2 is the value for sliding in the leaf spring or the so called pendulum stiffness of a link. The force F d determines the amount of damping in the hysteresis. A commonly used model to represent the two different stiffness values with the hysteresis is to use a linear spring and a friction element in series, in parallel with another linear spring, as shown in figure 11. It should be taken into account that the characteristics of leaf springs vary due to wear in running or deterioration or lubrication state.

The three parameters in the model described above can be derived from measurements. This model, however, is simplified since the shape of the hysteresis curve is usually rounded as shown in figure 10. Measurement results and more detailed descriptions of link suspensions can be found in [34]- [48].

Advanced simulation models

For lateral displacements of a double-link all four joints are assumed to start to slide at the same time; therefore the model in figure 11 is sufficient. In the longitudinal direction, however, it is more likely that the joints start to slide at different displacements as shown e.g. by Piotrowski [29]. He uses a set of four sliders and spring elements with different breakout forces in parallel to describe these characteristics. Also in a model used by Stiepel several elements in parallel are used [44].

To give a better representation of the rounded shape of the hysteresis curves, Fancher developed a model for truck leaf springs [45], [46] using exponential expressions. Jönsson [42] used a similar approach, where the total force over the suspension component is separated into piece-wise elastic and friction forces. The model is used for both leaf springs and double-links.

Another possibility to describe hysteresis with rounded shape for link suspensions is to use rolling contact theory, which has been proposed by Piotrowski [33]. Based on the slip velocity the creepage in the contact is calculated.

Modelling the three-piece bogie

Models of the central suspension

Most of the research in modelling three-piece bogies, such as [21], [22], is focussed on the central suspension element of the three-piece truck that provides damping with friction wedges. Early models of friction wedge suspensions recognized only vertical load-dependent friction force, later models included two-dimensional friction in the vertical and lateral directions [46], [50].

The first approach to account for possible angular and longitudinal displacements of bolster relative to the side frames is to introduce warping and longitudinal nonlinear resistance characteristics into the model, as it is done in [15], [17]. In such case the wedges are not modelled as separate bodies, but the equivalent force against displacement characteristics are introduced accounting for wedge parameters, such as inclination angle, width of the vertical surface, width of the inclined surface, friction coefficients on inclined and vertical surfaces, etc.

The second approach to account for all possible degrees of freedom between side frame and bolster is to introduce multiple contact points mapped along the edges of the wedge with two-dimensional friction force elements in each of them. Such an approach was used by Ballew et al [46], it is implemented in simulation tools such as VAMPIRE [52], and the Universal Mechanism software [52]. Numerous contact elements require an efficient numerical simulation algorithm to be implemented into the software that provides fast solution to resulting stiff system of equations, such as the one developed by Pogorelov [57]. The wedges are treated as massless. Contact type models allow the study of such complicated phenomenon as uneven distribution of contact forces over the wedge surfaces, implementation of resilient pads on wedge surfaces, jamming and wedging [54]. In paper [56] the authors included the mass of the wedge into consideration to study its dynamic properties.

Models of the axle to side frame interaction

In the first approach similar to friction wedges the axle to side frame interaction can be described by nonlinear equivalent characteristics as in [15], [17]. The dry friction interaction between the axle box crown and the side frame pedestal is modelled by two dimensional dry friction element in parallel with another nonlinear element that describes bumpstops in longitudinal and lateral dimension. A typical characteristic of the bumpstop element is presented in figure 12. To improve numerical integration the transition from clearance to bumpstop is often smoothed.

If the interaction between the crown and pedestal is a flat surface, then its width can result in roll stiffness that is produced by gravity. Such stiffness can be introduced into the model depending on the axle load. The second approach is to introduce multiple contact points on the edges of the crown with two-dimensional friction elements in them. The bumpstops are then also the contact elements between the axle box or adapter and the stops in the side frame jaws. Such approach is used in [57] as well as in Universal Mechanism software [52].

Models of the centre bowl and side bearers

The same approaches can be applied to models of the centre bowl to centre plate interaction and at the side bearers.

In the first approach, see [15], [17], centre plate to centre bowl interaction works simultaneously as one dimensional yaw friction and nonlinear roll and pitch torque with soft characteristics as shown in figure 13. Knowing the clearance in the side bearers the nonlinear roll characteristic can be linearized. The second approach is to introduce multiple contact points on the edges of the centre plate with two-dimensional friction elements in them. The interaction with the centre bowl rim is then also the contact elements. Such an approach is used in [57] as well as in Universal Mechanism software [52].

Stability

Freight vehicles in most cases operate at much lower speeds than passenger vehicles. Typical running speeds are at around 100 km/h. This suggests that stability investigations are not as important as for faster passenger vehicles. On the other hand freight vehicles often are much less damped than passenger vehicles and stability investigations are therefore necessary. Several of the wagon types introduced above can - in unfavourable running conditions - show significant hunting behaviour at speeds as low as 70 km/h.

In a bogie vehicle basically three types of hunting motion can arise:

 Wheelset hunting where one wheelset performs the hunting motion.

 M 0  M   c Mg  

 Bogie hunting where a whole bogie is taking over the hunting motion.  Carbody hunting where the carbody performs a yaw motion and the two bogies mainly follow the carbody with lateral motions, i.e. the whole vehicle takes over the hunting motion.

Carbody hunting is often a type of resonance phenomenon, where the Klingel hunting frequency given mainly by vehicle speed and conicity in the contact coincides with the yaw eigenfrequency of the carbody.

Hunting motion with a non-zero limit cycle depends on the wheel-rail geometry, the suspension and the masses and inertias of the vehicle. Since the mass and inertia, and in most cases the suspension stiffness and damping of the freight wagon will significantly change with load, the type of hunting motion observed usually differs between an empty and a loaded wagon. Since the stiffness values between axlebox and bogie frame (in a bogie vehicle) are lower in an unloaded vehicle, the risk for wheelset or bogie hunting is higher. In loaded vehicles, vehicle hunting can often be observed. Since the frequency of wheelset hunting is usually low (typically between 1 and 2 Hz) the wheel rail forces induced are relatively low and in most cases below the limit values stipulated in standards. Therefore, the vehicle design in reality allows for the carbody instability to happen in some conditions. Otherwise the suspension needs to be so stiff that the curving performance would suffer, and the amount of wear and RCF would increase significantly. The risk of carbody hunting can vary with the type of load since this can influence the yaw eigenfrequency of the carbody.

Due to the significant inherent non-linearity and non-smoothness of the suspension elements linearization of the models is usually not realistic. It is therefore necessary to perform time steppig integration with the full non-linear model. The task is in general to find the non-linear critical speed v B of the wagon as can be seen in the generic bifurcation diagram in figure 14.

Figure 14: Generic bifurcation diagram

In complex models it is very difficult to find the exact critical speed, for example with a path following method [58]. Therefore other engineering methods are used. One possibility that has been suggested e.g. by Polach [59] is to excite the vehicle with an initial disturbance that can either be deterministic or stochastic. After the initial disturbance the vehicle is run on ideal smooth track. If the oscillation vanishes the vehicle is regarded as stable. The simulations have to be repeated with increasing speed until the oscillations do not disappear. In that case the non-linear critical speed v b ( figure 15) is reached. A risk with this method is that the initial disturbance is not high enough to initiate a limit cycle oscillation and that the critical speed detected is higher than the real non-linear critical speed.

Another method to detect the non-linear critical speed is start the simulations at a very high speed to be sure that the vehicle has reached the non-zero attractor (limit cycle). Then the speed is continuously reduced until the limit cycle behaviour disappears. Polach also describes this method. It has been used for example by Boronenko et al [15] to tune the suspension of three-piece bogies.

A similar method, shown in figure 15, is suggested in [60] to determine the so-called non-linear critical speed. The difference to the method introduced above is that the speed is not reduced continuously but in discrete steps as suggested by True [98]. Figure 16 shows the bifurcation diagram for a loaded two-axle vehicle calculated with this method. It can be observed that only the stable branches of the bifurcation diagram can be determined, not the unstable part. The zero solution is also possible at least up to a speed of 120 km/h (bold solid line). This was simulated using the procedure above, starting from low speed and increasing the speed stepwise. Hoffman also investigated the stability of a two-axle wagon with link suspension [43], [61]. He uses the link model developed by Piotrowski [29]. The leaf springs model is based on Fancher et al [46]. Gialleonardo et al [62] extended this type of stability analysis for a two-axle wagon with link suspension on curved track. As can be seen in figure 18. the leading wheelset (y lw )

shows much smaller oscillation amplitudes than the trailing wheelset (y tw ) and the carbody. This is because the outer wheel of the leading wheelset experiences flange contact. In general the results show the presence of large periodic oscillations in narrow curves at commercial operating speeds. It is also shown in the paper that the coupling forces between wagon assemblies significantly reduce the oscillation amplitudes. Zhai et al [63] extended the stability analysis for a freight wagon with three-piece bogies to also include a visoelastic track structure. The stability analysis is performed according to the methodology suggested by Polach, which is explained above. The authors found that a lower critical hunting speed is obtained on elastic track compared with the rigid track case. The difference in the critical hunting speeds between the elastic track base and the rigid track base is 4.4% for the loaded freight car.

Curving

As indicated above simulations of the running behaviour of freight wagons in curves are often performed to investigate the risk of wheel wear and Rolling Contact Fatigue (RCF).

For passenger vehicles curving simulations are often performed on ideal track, i.e. the stochastic track irregularities are neglected. Authors are in this case interested in the quasistatic behaviour of the vehicle, i.e. the mean wheelset attack angles or the mean energy dissipation in the contact points. For freight vehicles with non-linear and non- smooth suspension this can lead to significant mistakes as shown in the example from Jönsson [42]. On ideal track the friction surfaces might stick together and force the wheelset into a more unfavourable position. Track irregularities help to get relative motion in the friction surfaces, which usually leads to better - and more realistic - steering behaviour of the vehicle. As seen in figure 19, the energy dissipation as a measure for the amount of wear or RCF, is much lower when simulating running with track irregularities. In one of their numerous studies on three-piece bogies Boronenko et al [15] investigate the reason for excessive flange wear in some of the Russian wagons. One conclusion is that the main reason for flange wear is the unstable behaviour of the bogies in curves (rutting mode) [16], when the bogie is flanging with a two-point contact situation instead of negotiating the curve using the wheel conicity. The flanging is the result of bogie warping, which increases the angle of attack compared to a radial position. In the article a number of different designs are discussed. Among others it is concluded that a bogie design with radial arms significantly reduces the angle of attack and the wear number in curves, see figure 20. Berghuvud [64] investigated the curving behaviour of different types of three-piece bogie with and without braking. He concluded that the influence of braking on the curving behaviour is complex. Braking can have a positive effect on the angle of attack of the wheelsets in a curve since it helps to overcome the static friction in the primary suspension. It can also increase the angle of attack if large longitudinal forces push the wheelset longitudinally towards the limit of the play and thus lock the wheelset in an unfavourable position.

Vehicle Resistance

Radially steering bogies do not only reduce flange wear in curves but also reduce the required traction energy. The inner leading wheel is less affected and the trailing wheelset has much smaller values. With radial steering, ( figure 22) the leading axle also has very small creepages. This results in lower wear and running resistance. As a result on track with tight curves more than 20% of the overall running resistance can be reduced with similar levels of energy saving [66].

Of course radial steering may affect running stability on straight track. Therefore bogie designs with cross anchors such as the TVP 2007 or the Leila bogie have an advantage over individual radial steering axles as in the swing hanger bogie.

Influence of curving on wheel and rail damage phenomena

As mentioned in the introduction to this section the curving performance of a freight wagon is very important for the level of wheel and rail damage. This means in turn that the vehicle track interaction in curves determines to a large extent the maintenance cost for the whole system. In [66] Fröhling discusses the influence of, among others, bogie design, bogie maintenance and the wheel/rail interface in heavy haul operation on different damage phenomena on wheels and rails. In a later publication Fergusson et al [67] present an analysis of wheel wear as a function of the relationship between the lateral and longitudinal primary suspension stiffness and the coefficient of friction at the centre plate between the wagon body and the bolster to minimise the wheel wear rate of a self-steering three-piece bogie without compromising vehicle stability. Simulation results indicate that wheel wear is theoretically the lowest for low lateral and longitudinal primary suspension stiffness and no friction at the centre plate. Casanueva et al [68] extend the wear prediction methodology for freight wagons to also include switches and crossings. It is concluded that wear on some parts of the wheel profile can only be explained with running through switches.

Tunna and Urban [69] carried out a parametric study to quantify the effects of various freight vehicle parameters on the generation of RCF. Three different freight suspensions wer considered: an enhanced three-piece bogie, a rigid-frame bogie with primary suspension, and a two-axle vehicle with leaf springs. Simulations were performed for track curvature ranging from 400 to 10 000 m. To judge the generation of RCF the Tgamma model from Burstow [70] was used. It is stated that parameters that clearly need to be considered when evaluating rail surface damage are curve distribution, track quality, conicity, vehicle type and loading state of the wagon. Since several parameters are line dependent it is concluded that a route based analysis is necessary.

In [71] a simulation model of an iron ore wagon with three-piece bogie is developed to investigate the risk of RCF on the Swedish and Norwegian iron ore line. 43 load cases with various conditions were used as inputs. The risk for RCF was estimated with the so-called shakedown map. The wear number, which is the product of creepages and creep forces, was calculated to estimate where initiated cracks develop or are worn away. In figure 23 areas on the wheel profile with high risk of RCF can be seen. The area on the wheel tread coincides very well with field observations of RCF but the areas in the flange root and on the flange did not show RCF damage. It can be concluded that the energy dissipation is high enough to wear away initiated cracks. It seems that simulation of the curving behaviour of freight wagons can provide valuable information about the risk of wheel damage for specific operating conditions.

In [71] a simulation by Dukkipati and Dong examine the effects of a freight wagon running over a dipped joint. In a very recent paper Wang and Gao investigate the wheel wear of a freight vehicle with three-piece bogie in curves [99]. It is shown that wear is most severe on the outer leading wheel in the bogie.

Parameter identification

The establishment of the correct parameters for use in computer models is clearly of great importance. Some parameters can easily be measured or provided by the manufacturers but others are very difficult to establish. Ren et el [74] demonstrate the use of a test rig with a sliding plate underneath one wheelset to establish key parameters. The sliding plate is moved with actuators and forces measured to allow the lateral, shear and warp stiffness to be established as well as the friction characteristics of the bogie.

Modern Developments

The British Rail HSF Bogies

Wickens and colleagues at British Rail Research carried out theoretical and practical work aimed at understanding the dynamic performance of two axle freight vehicles [75], [76]. The aim was to increase the operating speed of freight vehicles and reduce the rate of derailments. A series of experimental two axle vehicles were constructed to confirm the results of the analysis. They included coil springs and viscous dampers and longitudinal rods to control yaw motion and were initially tested on a full size roller rig.

Computer simulations of curving and stability were carried out with various damper configurations and on-track tests of several prototypes were undertaken

The result of this work was the prototype 'HSFV.4' high speed freight vehicle with viscous damping ( figure 24) which was tested at speeds of up to 120 km/h and proved to run without hunting for a wide range of effective conicity values.

The Unitruck running gear

The Unitruck single-axle running gear with lateral "swing hangers" was first developed for the American market and in the 1990's adjusted to suit European conditions. Vehicles with Unitruck running gear [76] are today used both in North America and Europe. They have only one stage suspension, which also includes friction damping. As in the Y25 bogie, the vertical force in the primary suspension is used to preload the different friction components via an inclined surface. Figure 25 left shows the wedge element, which is in series with one of the coil springs and in contact with the carbody via an inclined friction surface; the vertical surface in contact with the saddle is also a friction surface. Newer designs have substituted the inclined friction surface by a roller (figure 25 left) [77], thus enabling the displacement in the longitudinal direction, but reducing longitudinal damping. Also, adding a coupling plate in the centre of the coil springs increases longitudinal stiffness (Figure 25 right), which improves critical speed compared to the running gear with rollers and classic coil springs. The 'Swing Motion' bogie ( figure 26) is a variant of the three-piece freight bogie and was originally developed for heavy haul operations in North America. In the Swing Motion design an additional cross member or transom is included which connects the two side frames together via pivots at the base of the secondary spring pack. The bolster still sits on the top of the spring packs and is damped through friction wedges. A pivot between the axle boxes and the side frames is also included so that the side frames can pivot or swing to accommodate lateral motion of the bolster. The swing motion gives increased lateral stability at speeds up to 176 km/h and is claimed to reduce wheel and rail wear, reduce rolling resistance and forces on track and vehicle body compared with standard three-piece bogies.

The 'LTF' bogie

In the 1980s British Rail Research in the UK developed a novel, track friendly bogie using passenger vehicle technology. The LTF25bogie is shown in figure 27 and is described in [79].

Figure 27: The 'LTF25' bogie

The LTF25 bogie was specifically designed to reduce dynamic track forces and as part of this effort was made to reduce the unsprung mass. Small wheels (813 mm diameter) were used and inside axle boxes giving a 30% reduction in wheelset mass although this necessitated the use of on-board hotbox detectors.

Primary suspension is through steel coil springs and secondary suspension is through rubber spring elements and hydraulic dampers.

The high cost of the LTF25 bogie and concerns about axle fatigue with inboard axle boxes militated against its adoption but Powell Duffryn produced a modified version of the bogies known as the TF25 bogie (shown in figure 28) which has achieved considerable production success.

The 'Gigabox' bogie

The 'Gigabox'bogie uses pedestal units containing progressive rubber springs with integral hydraulic damping as shown in figures 29 and 30). The system was developed by ContiTec and SKF and is claimed not to require maintenance for up to 1million km and to provide good noise and vibration isolation. A reduction of up to 20% in lateral forces is claimed as well as a 2 dB reduction in noise.

The Double Rubber Ring Spring (DRRS) bogie

Originally designed by Talbot the DRRS bogie uses double rubber torroidal ring springs with load proportional friction damping as shown in figure 31. Container wagons with DRRS bogies entered service with the DB 'Inter Cargo Express- System'. Maximum axle-load ranges from 22.5 t at 100 km/h to 18.375 t at 160 km/h.

Advances in three-piece bogies

The major drivers for advances of AAR three-piece bogies were tightening ride performance and track impact standards, such as M-1001 [79] and M-976 [80], since 2000.

An overview of improvements in the suspensions is given in [81]. Suspension springs tend to increase the deflection. Using higher control springs under the wedges increases friction under the empty wagon thus providing its better stability, and makes damping less dependent on the wear of wedges themselves. Different height of the inner and outer springs allows having lower lateral stiffness of the suspension under the empty wagon, thus improving its running performance. Using the set of 9 double springs per each side of the bogie increases warping resistance.

The innovative designs of the wedges are shown in figure 32. Both designs aim to increasing the warping resistance of the bogie. The split wedge consists of two symmetric parts inclined towards each other and interacts with the spatial insert in the bolster pocket. In the spatial wedge the surfaces are inclined in the other direction and they are wider than the vertical surface, which gives the same effect. In the interaction between the side frame and the wheelset axle various elastic components are introduced to reduce unsprung mass as well as to reduce resistance to wheelset displacement in plane, thus reducing the lateral track forces. Some of the designs of elastic shear pads are shown in figure 33. The rigid side bearings with clearances have transformed in modern three-piece bogies into constant contact side bearings, incorporating the elastic element compressed by the weight of the car body, [82]. Examples of the design are shown in figure 34. Constant contact side bearings provide yaw damping for the bogies on straight track, as well as additional car body roll resistance for better curving performance. The rollers positioned with a clearance provide rigid bumpstop that limits the elastic element deflection without increasing the yaw resistance. There are several devices used to increase warping stiffness of three-piece bogies, the most common of which is using cross-braces between the side frames shown in figure 35.

Cap

Elastic element

Cage Wear resistant element

Insert

Roller

Cap

Elastic element

Cage 1 - top brace; 2 - bottom brace; 3 - bolt; 4 - washer; 5 - nut; 6 - fastening unit; 7 - rings; 8 - locking plate; 9 - washer; 10 - bolt; 11 - elastic pad; 12 - safety wire; 13, 14 - bracket; 15, 16, 17 - plate; 18 - key Figure 35 Cross-braces between side frames.

Using the concept of shear and bending stiffness of the bogie Scheffel [83], developed several novel designs of three-piece bogies (figure 36). At first the horizontal motion of the frame is decoupled from the wheelsets by horizontally soft primary suspension. Then the axle boxes are interconnected through sub-frames or arms by elastic elements that support their radial position in curves, but resist in-phase yaw [84]. Scheffel bogies having the axle load of 32 t provide mileage between wheel turning of up to 1.5 million kilometres thus proving the high efficiency of the design to reduce track forces.

The Lenoir pusher spring

Various alternatives to the double Lenoir linkage have been explored with the aim of providing reduced longitudinal stiffness at low cost. One example is the 'Lenoir pusher spring' which consists of a plunger and washer springs mounted opposite the Lenoir pusher ( figure 37). This allows more longitudinal motion than the conventional Piotrowski [86] reports how this arrangement has been shown to give good performance in a prototype vehicle with significant reductions in wheel wear.

The RC25NT Bogie

Eisenbahn Laufwerke Halle (Germany) has developed the RC25NT self-steering three- piece bogie with direct inter-axle linkages which was presented at the Innotrans exhibition in 2010) [87] ( figure 38). The bogie has horizontally soft rubber bushes in the primary suspension and flexicoil dual rate springs with friction damping in the secondary suspension. The bogie is equipped with disk brakes. The aim of the development was to build a bogie capable of stable running up to 120 km/h, keeping low noise criteria and negotiating curves with minimum of wear. The bogie is designed to replace the Y25 type bogie without changes to the wagon body.

Simulations have shown that the RC25NT provides better stability on straight track than the Y25 (figure 39) and less wheel and rail wear in curves ( figure 40). The bogie was tested according to the UIC 518 standard in Sweden in 2010 for speeds up to 160 km/h. The RC25NT demonstrates that direct inter-axle linkages can allow freight car bogies to run at 120 km/h with proper steering and low wear in curves.

The 'LEILA' Bogie

The LEILA bogie ('LEIchtes und LärmArmes GüterwagenDrehGestell' with the meaning of light and low noise freight bogie) is a passive radial steering bogie with a maximum axle load of 22.5 t and was developed between 2000 and 2005 during a German and Swiss research project [88]. The Institute of Rail Vehicles of the Technische Universität Berlin was one of the involved partner. The aim to develop this bogie was:

 to reduce the noise emissions of freight wagons;  to reduce the mass of a bogie to be under 4 t and  to reduce significantly wear and running resistance.

In addition:

 the reliability and availability of freight wagons;  transparency in the transport chain;  the active and passive safety of the freight traffic and;  the transport velocity should be similarly increased [89]. The primary layer consists of rubber springs and the load dependent stiffness characteristics are separated in vertical and horizontal working components. The bogie has passive radial steering technology of the wheelsets. Wheelsets are able to rotate about the vertical axis without any external energy but only by the roll radius difference between the inner and outer wheel. Both wheelsets are connected with cross anchors; mounted on opposite axle boxes. The secondary layer is defined UIC centre of pivot and side bearer (latter guarantees the exchangeability to Y25 bogies). In addition, the centre of pivot has an elastically bearing using a secondary rubber spring. The LEILA bogie prototype was examined during various field tests where it demonstrated its advantages compared to a Y25 bogie. The noise emissions were reduced up to 18 dB(A) compared to a Y25 bogie with cast iron brake blocks and up to 8 dB(A) compared to a Y25 bogie with composite blocks (k- blocks). But the bogie failed at that time to enter the market. During the very good ongoing homologation process the producer of the bogie decided to stop the production of new freight wagons and bogies. Therefore the homologation was stopped and not finished just for commercial reasons. Right now as more and more EMUs are produced with inner bearings it is expected that the acceptability of inner bearing bogies with the advantages less weight and lower forces at the axles in curves will be more acceptable. As with the Leila bogie the cross anchor couples the two axles so that they turn with a phase shift of 180°. This stabilizes the radial steering effect even when the wheel-rail contact is not perfect and the second very important effect is dynamic stabilisation without yaw dampers for high speed straight track running. On curvy track significant flange and running surface wear reduction and also significant reduction of the running resistance occur.

The SUSTRAIL Bogie

The aim of the SUSTRAIL project is to promote modal shift of freight in Europe from road to rail. The SUSTRAIL project intends to provide the approach, structure, and technical content to support this modal shift through improvements in the railway freight system including innovations in rolling stock in track components. The project includes workpackages focused on market research, vehicles, infrastructure and assessment of cost benefits. The work described here is part of workpackage 3: 'The freight vehicle of the future'.

The main scientific and technological innovations being considered for the SUSTRAIL freight vehicle are:

 The development of advanced vehicle dynamics concepts based on new wheel profiles and improvements in suspension design responding to the needs of a mixed traffic railway;  Developments in the traction and braking systems for high speed low impact freight operation;  Novel designs and materials for lightweight high performance freight wagon body vehicles and bogie structures;  Advanced condition based predictive maintenance tools for critical components of both railway vehicles and the track;  Identification of performance based design principles to move towards the zero maintenance ideal for the vehicle/track system.

Partners in the project have carried out a technology review to identify the potential innovative technologies to meet the above requirements and the results have been ranked and two concept vehicles are being designed. The 'Conventional' vehicle will use optimised existing technology and a demonstrator for this is being built as part of the project. The 'Futuristic' vehicle will utilise technology which has not yet been proven in the railway field but has potential to make greater improvements.

Simulations have been carried out of the dynamic behaviour of the concept design vehicles running on typical track in tare, part laden and fully laden cases. In line with the target of a 50% reduction in lateral forces on the track and stable running at 140 km/h a suspension using double Lenoir linkages, longitudinal linkages between axle boxes and centre pivot suspension has been selected. Computer simulation has been used to optimise the suspension and to select suitable parameters for the various components. Assessment of the results is based on:

 Stability: stable running on typical European track at the design speed of 140km/h must be ensured and ride quality (vertical lateral and longitudinal accelerations experienced by the goods transported) will be assessed.  Reduced track forces: track geometrical deterioration (ballast settlement and horizontal level, alignment and buckling), rail surface damage (wear, rolling contact fatigue -RCF) and track components damage (sleeper cracking, rail pad deterioration, rail fatigue, fastening deterioration) will all be assessed.

A benchmark vehicle has been selected based on a Y25 bogie and flat bed wagon and has been used to allow quantification of the benefits of the new design.

A number of radical innovations were considered during the technology review stage of the project but it was decided that the use of double Lenoir link primary suspension as in the Y37 series of bogies (figure 44), would be investigated. The double Lenoir link suspension provides much lower longitudinal primary stiffness while still utilising standard components and methods which are well established within the railway industry. this work A model of the SUSTRAIL vehicle was set up with double Lenoir links using the computer simulation tool Gensys and the influence of variations in the suspension parameters on the critical speed of the wagon was simulated. Straight track was used for this simulation and an initial lateral disturbance was introduced followed by ideal track with no irregularities. Axle load is 22.5 t, wheel profile is S1002 and rail profile UIC60 inclined at 1:40. The wheel rail coefficient of friction is set at 0.35. The wagon speed was reduced from an initial 170 km/h and critical speed assumed to have been reached when the track shifting force (∑ ) drops below 2.5 kN. An example is shown in figure 46. Further variations were carried out and the effect of the friction coefficient and stiffness within the suspension on the maximum contact force is shown in figure 49. Figure 49: The effect of friction coefficient and spring stiffness on the contact force It can be seen that the maximum vertical contact forces tends to increase with the damping and with the spring stiffness. In order to improve the running behavior of the SUSTRAIL vehicle it was decided to assess the benefit of linkages provividing longitudinal stiffness between the axleboxes using a radial arm. A radial arm designed by Scheffel [90] was studied previously in the Infra-Radial project [91] which aimed to develop a bogie for heavy haul vehicles (axle loads over 25T) with reduced life cycle costs. Tests using the radial arm with four different primary suspension types showed good results with stable running and radially aligned wheelsets in curves. Wear of the wheels was seen to reduce significantly [91]. In the work reported here simulation was carried out using MEDYNA for the SUSTRAIL vehicle with double Lenoir links and modified radial arms. Simulations have confirmed that the radial arm should provide lateral stiffness between the wheelsets and optimised parameters have been defined. A prototype of the SUSTRAIL freight vehicle is being constructed by REMARUL engineering. In addition to Vertical coils spring stiffness [%] the innovative suspension described in this paper the SUSTRAIL vehicle will have disk brakes with an electronic control system. The bogie design is shown in figure 50.

Longitudinal dynamics

The longitudinal dynamic behaviour of railway vehicles is often neglected as the link to the vehicle track interaction is generally not significant and it has been common to assume that all vehicles of the same type in a train will behave identically. In heavy haul freight applications however where long trains are common the effect of longitudinal dynamics can become significant. In [71] for example Qi et al model the longitudinal behaviour of a long train including traction and braking and the coupling between vehicles. Belforte et al [93] also analyse the effects of severe traction and braking forces on longitudinal dynamics.

There are several areas where longitudinal dynamics can interact with the general vehicle dynamics. These include:

 Wheel unloading on curves due to lateral components of coupler forces;  Wagon body pitch due to coupler impact forces and  Bogie pitch due to coupler impact forces Cole [94] describes how these effects can be assessed in different cases and McClanachan [95] and El Sibaie [96] present results of computer simulations including coupler models.

Freight vehicles have to provide satisfactory performance at low cost in tare and laden condition on varying track quality. This has resulted in several standard designs including the Y25 and the three-piece bogie. These designs use friction damping proportional to the vehicle mass to provide good dynamic performance at all loading conditions. In recent years vehicle designers have tried to improve on the dynamic performance of freight wagons and the use of computer tools have helped to overcome the compromise between good curving performance and stability at higher speeds. This has resulted in a number of innovative designs with demonstrable performance improvements but it is notable that few of these have yet to make significant impact in the worldwide freight train fleets.

A key reason for this lack of adoption is probably the innately conservative nature of the railway industry. Of course this often has a sound basis in, for example, the benefit of using standard components which allow effective maintenance of widely dispersed fleets of vehicles but in order to allow the benefits of the innovative techniques and designs summarised in this paper it is time to reconsider the design of freight vehicles. This could allow increases in speed with lower impact on track and environment and a resulting step change in performance of the railway system. One encouraging sign is the establishment in some countries of track access charging which benefits the use of vehicles with 'track friendly' suspension. Together with emerging legislation and growing pressures on system capacity it is likely that the demand for freight vehicles with higher dynamic performance will climb rapidly.

Rail freight only can contribute in mitigating the environmental impacts of transportation if the knowledge and todays experience for innovative products is used. Some basic thoughts can be found here and in [97]. Optimising performance through the development of innovative products is to be planned and procured carefully. This paper has demonstrated that freight vehicle designers have innovative designs of running gear and computer simulation tools ready for this challenge.

Figure 1 :1Figure 1: Freight wagon from Kockums Sweden, built in 1882 [4]. -

Figure 2 :2Figure 2: UIC double link suspension. -

Figure 3 : Double link suspension [ 8 ]. Parts of double link (a), assembled double link (b) and mounted double link (c).38Figure 3: Double link suspension [8]. Parts of double link (a), assembled double link (b) and mounted double link (c). -

Figure 4 :4Figure 4:. DB bogie Type 931 [7]. -

Figure 5 :5Figure 5: DB bogie Type 665 [7]. -

Figure 7 : Model 18- 100 bogie: a - general view, b - central suspension scheme, c - primary 'suspension' scheme ( 1 - wheelset; 2 - side frame; 3 - bolster; 4 - braking leverage; 5 - central pivot; 6 - rigid side bearings; 7 - suspension springs; 8 - friction wedge; 9 -7100123456789Figure 7: Model 18-100 bogie: a-general view, b-central suspension scheme, cprimary 'suspension' scheme (1-wheelset; 2-side frame; 3-bolster; 4-braking leverage; 5-central pivot; 6-rigid side bearings; 7-suspension springs; 8friction wedge; 9-axle-box) -

Figure 8 : Force-displacement curve of Coulomb friction model (left) and Coulomb model with spring in series as in [ 29 ]829Figure 8: Force-displacement curve of Coulomb friction model (left) and Coulomb model with spring in series as in [29] (right). -

Figure 9 : Friction element with spring in series.9Figure 9: Friction element with spring in series. -

Figure 10 : Typical force-displacement diagram of leaf spring/link suspension. Example of curve for small displacements around static equilibrium.10Figure 10: Typical force-displacement diagram of leaf spring/link suspension. Example of curve for small displacements around static equilibrium. -

Figure 11 : Model for leaf spring or link suspension as used for example by KTH [ 40 ]. See figure 10 for definition of k1 and k2.114010Figure 11: Model for leaf spring or link suspension as used for example by KTH [40]. See figure 10 for definition of k1 and k2. -

Figure 12 Model for bumpstop element (∆ - clearance, - stiffness of the bumpstop)12Figure 12 Model for bumpstop element (∆-clearance,-stiffness of the bumpstop) -

Figure 13 Model for center plate element (∆ - distance between center plate edge and car body center of gravity, - roll angle, - weight of the car body per one center plate, - roll torque, - equivalent roll stiffness)13Figure 13 Model for center plate element (∆-distance between center plate edge and car body center of gravity,-roll angle,-weight of the car body per one center plate,-roll torque,-equivalent roll stiffness) -

Figure 15 : Procedure to find the non-linear critical speed [ 60 ].1560Figure 15: Procedure to find the non-linear critical speed [60]. -

Figure 16 : Bifurcation diagram for a loaded two-axle vehicle with link suspension ( 21 t axle load) Wheel: somewhat worn S1002. Rail: Nominal UIC60 [ 42 ].162142Figure 16: Bifurcation diagram for a loaded two-axle vehicle with link suspension (21 t axle load) Wheel: somewhat worn S1002. Rail: Nominal UIC60 [42]. -

Figure 17 .17shows attractors for two different types of freight wagons. The results are in principle quite similar to those in figure 16. -

Figure 17 : Attractors for the Hbbills 311 and the G69 freight wagons. The model with the measured characteristics of the UIC links is damping less than the model with the cylindrical characteristics. The hunting attractor exists even for low speeds [61].17Figure 17: Attractors for the Hbbills 311 and the G69 freight wagons. The model with the measured characteristics of the UIC links is damping less than the model with the cylindrical characteristics. The hunting attractor exists even for low speeds [61]. -

Figure 18 Map of lateral oscillation amplitude in single wagon as function of curve radius [62].18Figure 18 Map of lateral oscillation amplitude in single wagon as function of curve radius [62]. -

Figure 19 : Energy dissipation. Comparative simulation with and without track irregularities. Two-axle vehicle with link suspension. 22 . 5 t axle load [ 42 ].1922542Figure 19: Energy dissipation. Comparative simulation with and without track irregularities. Two-axle vehicle with link suspension. 22.5 t axle load [42]. -

Figure 20 : Angle of attack (a) and wear number (b) for wagons in a curve of 200 m radius at 60 km/h with 18- 100 bogies respectively bogies with radial arm upgrade [ 15 ].2010015Figure 20: Angle of attack (a) and wear number (b) for wagons in a curve of 200 m radius at 60 km/h with 18-100 bogies respectively bogies with radial arm upgrade [15]. -

Figure 21 : Y25 bogie running in a 300m curve Wheel slip lateral and longitudinal at all wheel rail contact points, 90 t tank car with a Y25-Bogie in a 300 m curve, speed 80 km/h, lateral acceleration aq= 0, 67 m/s², s1002 Wheel profile, UIC 60E1, 1 Figure 22 : Radially steered bogie running in a 300 m curve Wheel slip lateral and longitudinal at all wheel- rail contact points, 90 t tank car with a Leila-Bogie in a 300 m curve, speed 80 km/h, lateral acceleration aq= 0, 67 m/s², s1002 Wheel profile, UIC 60E1, 121903006712230090300671Figure 21: Y25 bogie running in a 300m curve Wheel slip lateral and longitudinal at all wheel rail contact points, 90 t tank car with a Y25-Bogie in a 300 m curve, speed 80 km/h, lateral acceleration aq= 0,67 m/s², s1002 Wheel profile, UIC 60E1, 1:40 rail inclination -

Figure 23 : Calculated RCF positions of the wheel with corresponding average wear number. The far-left line is also reported as the observed approximate location for RCF initiation.23Figure 23: Calculated RCF positions of the wheel with corresponding average wear number. The far-left line is also reported as the observed approximate location for RCF initiation. -

Figure 24 :24Figure 24: The HSFV.1 experimental freight wagon -

Figure 25 :25Figure 25: Unitruck running gear (left) and modifications for improving curving behaviour (right). -

Figure 28 :28Figure 28: The TF25 bogie -

Figure 29 : The Gigabox bogie Figure 30 :2930Figure 29: The Gigabox bogie -

Figure 31 : The DRRS bogie and cross section31Figure 31: The DRRS bogie and cross section -

Figure 32 :32Figure 32: Split wedge (left) and spatial wedge (right). -

Figure 33 : Adapter Plus ® by Amsted (left) and layered shear pad in Russian 18- 9800 bogie (right).339800Figure 33: Adapter Plus ® by Amsted (left) and layered shear pad in Russian 189800 bogie (right). -

Figure 34 : Constant contact side bearing with springs (left) and with non-metal element and roller (right).34Figure 34: Constant contact side bearing with springs (left) and with non-metal element and roller (right). -

Figure 37 :37Figure 37: The Lenoir pusher spring -

Figure 38 : RC25NT bogie with direct inter-axle linkages Figure 39 : Simulation stability results for RC25NT bogie vs. Y25 bogie (upper figure = high conicity, lower figure = low conicity)Figure 40 : Simulated wear number for RC25NT bogie vs. Y25 bogie383940Figure 38: RC25NT bogie with direct inter-axle linkages -

Figure 4141Figure 41 and 42 show the main components of this bogie. Compared to the standard bogies such as Y25, the LEILA bogie has inner bearings. The resulting better force flow lead to a weight reduction of the bogie frame and wheelset resulting in an overall weight reduction of 750 kg per bogie compared to Y25 bogie. At the web of the wheels (diameter: 920 mm), disc brakes are mounted. The primary layer consists of rubber springs and the load dependent stiffness characteristics are separated in vertical and horizontal working components. The bogie has passive radial steering technology of the wheelsets. Wheelsets are able to rotate about the vertical axis without any external energy but only by the roll radius difference between the inner and outer wheel. Both wheelsets are connected with cross anchors; mounted on opposite axle boxes. The secondary layer is defined UIC centre of pivot and side bearer (latter guarantees the exchangeability to Y25 bogies). In addition, the centre of pivot has an elastically bearing using a secondary rubber spring. The LEILA bogie prototype was examined during various field tests where it demonstrated its advantages compared to a Y25 bogie. The noise emissions were reduced up to 18 dB(A) compared to a Y25 bogie with cast iron brake blocks and up to 8 dB(A) compared to a Y25 bogie with composite blocks (kblocks). But the bogie failed at that time to enter the market. During the very good ongoing homologation process the producer of the bogie decided to stop the production of new freight wagons and bogies. Therefore the homologation was stopped and not finished just for commercial reasons. Right now as more and more EMUs are produced with inner bearings it is expected that the acceptability of inner bearing bogies with the advantages less weight and lower forces at the axles in curves will be more acceptable. -

Figure 41 : Main components of LEILA bogie [ 88 ] Figure 42 : Leila Bogie from beneath with the inner bearings, cross anchor and wheel disc brakes clearly visible 4 .4188424Figure 41: Main components of LEILA bogie [88] -

Figure 43 : TVP2007 bogie by Tatravagónka a.s.43Figure 43: TVP2007 bogie by Tatravagónka a.s. -

Figure 44 :44Figure 44: A suspension with double Lenoir links -

Figure 46 : A sample simulation results showing the establishment of the critical speed for the SUSTRAIL vehicle with double Lenoir links46Figure 46: A sample simulation results showing the establishment of the critical speed for the SUSTRAIL vehicle with double Lenoir links -

Figure 47 :47Figure 47: The effect of Lenoir link angle, length and friction coefficient on the critical speed of the SUSTRAIL vehicle -

Figure 48 : Maximum vertical force on the rail for the SUSTRAIL vehicle running at 120 km/h48Figure 48: Maximum vertical force on the rail for the SUSTRAIL vehicle running at 120 km/h -

Figure 50 :50Figure 50: The prototype SUSTRAIL freight bogie - - -side frame; 2-bolster; 3-wheelset; 4-primary suspension; 5-elastic connection between sub-frames Figure 36: Scheffel HS bogie (left) and bogie retrofitted with Radial Arm design (right). - - -

- - - - - - European freight vehicle running gear: today's position and future demands - - MHecht - - - - PartF, Journal of Rail and Rapid Transit - - 215 - - - - - Proc. Of the Inst. Of Mech. Engrs. - - - - - White Paper-Roadmap to a Single European Transport Area-Towards a competitive and resource efficient transport system - - - European Commission - - 144 - - - - COM - - - - - Freight Wagon Running Gear-a review, KTH Railway Division - - P.-AJönsson - - - - Stockholm - - - - - - - Swedish: Järnvägsfordon från Kockums), Kockums industrier -

Malmö, Sweden, Pamphlet

- - - - - Railway vehicles from Kockums - - - - - UIC Code 517. Wagons-Suspension gear (Standardisation) - - - 6th edition 1-7-79. Reprint 1-1-89. incorporating 8 amendments - - - - - Laufwerkskonstruktion und Erhöhung der Radsatzlasten im Güterverkehr. ZEV-Glasers Annalen 107 - - TMadeyski - - - - - - - - - - - - LMüller - - - WNiedermeyer - - Weiterentwickelte Güterwagendrehgestelle der Deutschen Bundesbahn für 22.5 t Radsatzlast-wieder nach dem Lenkachsenprinzip. ZEV-Glasers Annalen - - - 111 - - - - - - - - Dynamic analysis of a freight car with standard UIC single-axle running gear - - HLange - - - - KTH Railway Technology - - 34 - - - - - - - - Running behavior of railway freight wagon with single axle running gear - - SStichel - - 1998:40 - - - KTH - - - Division of Railway Technology - - -TRITA-FKT Report - - - - - How to improve the running behavior of freight wagons with UIC-link suspension. Vehicle System Dynamics Supplement 33 - - SStichel - - - - - - - - - - - Running behavior of freight wagons with link bogies. TRITA-FKT Report 1999:12, Division of Railway Technology - - SStichel - - - - KTH - - - - - - - Neue Erkenntnisse über das Verschleissverhalten von Güterwagendrehgestellen, ZEV Glasers Annalen 111 - - WSpecht - - - - - - - - - - - Association of American Railroads. Manual of standards and recommended practices. Section D. Trucks and truck details - - - 130 - - - - - - - Bogies two-axle three-piece for freight wagons of 1520 mm gauge railways. General technical specifications - - - GOST 9246-2013 - - 38 - - - - - - - Refining the wedge friction damper of three-piece freight bogies - - AOrlova - - - RomenYu - - - - Vehicle System Dynamics - - 46 - - - - - - - - - Influence of construction schemes and parameters of three-piece freight bogies on wagon stability, ride and curving qualities - - YBoronenko - - - AOrlova - - - ERudakova - - - - Vehicle System Dynamics - - 44 - - - - - Supplement - - - - - Identification of parameters for spatial wedge system implemented in freight bogie design - - AOrlova - - - - Proceedings of the 10th mini-conference on Vehicle System Dynamics, Identification and Anomalies. Ed. I. Zobory. ISBN 978 963 420 968 - the 10th mini-conference on Vehicle System Dynamics, Identification and Anomalies. Ed. I. Zobory. ISBN 978 963 420 968

Budapest

- - Komaromi Nyomda es Kiado Kft - - 3 - - - - - - - - A review of modeling methods for railway vehicle suspension components. Vehicle System Dynamics - - BMEickhoff - - - JREvans - - - AJMinnis - - - - International Journal of Vehicle Mechanics and Mobility - - 24 - - - - - - - - - Modelling of suspension components in a rail vehicle dynamics context - - Bruni S - - - JVinolas - - - MBerg - - - OPolach - - - StichelS - - - - Vehicle System Dynamics - - 49 - 7 - - - - - - - - - Modeling and Simulation of Freight Wagon with Special attention to the Prediction of Track Damage - - SStichel - - - P-AJönsson - - - CCasanueva - - - HosseinNia - - - S - - - - International Journal of Railway Technology - - 3 - - - - - - - - Modelling friction wedges, Part I: The state-of-the-art - - PEKlauser - - - - Proceedings of IMECE04 2004 ASME International Mechanical Engineering Congress & Exposition - IMECE04 2004 ASME International Mechanical Engineering Congress & Exposition

Anaheim (CA

- - American Society of Mechanical Engineering - - - - - - - - A review of dynamics modelling of friction wedge suspensions. Vehicle System Dynamics - - QWu - - - CCole - - - MSpiryagin - - - QSun - - - - International Journal of Vehicle Mechanics and Mobility - - 52 - 11 - - - - - - - - - Non-smooth Problems in Vehicle Systems Dynamics - - - Springer - Berlin Heidelberg - - - - - - - Rail Vehicle Dynamics - - EAnderson - - - MBerg - - - SStichel - - - - KTH Royal Institute of Technology - - - - - - - - - Simulation. In: Iwnicki, editor, Handbook of Railway Vehicle Dynamics - - OPolach - - - MBerg - - - SIwnicki - - - - Taylor & Francis - - London - - - - - - - Modelling of wedge dampers in the presence of two-dimensional dry friction - - FXia - - - - Vehicle system dynamics -

Lingby, Denmark

- - - 37 - - - - - - - - Modeling and Dynamics of Friction Wedge Dampers in Railroad Freight Trucks - - ABKaiser - - - JPCusumano - - - JFGardner - - - - Vehicle System Dynamics - - 38 - 1 - - - - - - - - - Multibody simulation of a freight bogie with friction dampers - - NBosso - - - AGugliotta - - - ASoma - - - - Railroad Conference - - ASME/IEEE Joint - - - - - - - - - Model of the UIC link suspension for freight wagons - - JPiotrowski - - - - Archive of Applied Mechanics - - 73 - 7 - - - - - - - - - Smoothing dry friction damping by dither generated in rolling contact of wheel and rail and its influence on ride dynamics of freight wagons, NVSD - - JPiotrowski - - - - 48 - - - - - - - - Equivalent viscous damping models of coulomb friction in multi-degree-of-freedom vibration systems - - XTan - - - RJRogers - - - - Journal of Sound and Vibration - - 185 - 1 - - - - - - - - - Modelling of a two-dimensional Coulomb friction oscillator - - FXia - - - - Journal of Sound and Vibration - - 265 - 5 - - - - - - - - - A substitute model of two-dimensional dry friction exposed to dither generated by rolling contact of wheel and rail - - JPiotrowski - - - - Vehicle System Dynamics - - 50 - 10 - - - - - - - - - The dynamics of a railway freight wagon wheelset with dry friction damping Vehicle System Dynamics 44 supplement - - HTrue - - - RAsmund - - - - - - - - - - - Flexibility of trapezoidal springs - - - ORE - - - - - - - - - ORE, Parabolic springs for wagons (design, calculation, treatment) - - - Utrecht, 43 - - - - - - - Improvement of the running stability of existing RIV wagons required to run under any loading conditions at speeds of 80 km/h - - - ORE - - - - - - - - - ORE: Etude de la stabilité transversale d'un véhicule ferroviaire à deux essieux - - MRJoly - - - - Utrecht - - - - - - - Computer simulation of freight vehicles with leaf springs - - JBAyasse - - INRETS/RE- 01-046-FR - - - - -Technical report - a comparison between different packages, INRETS - - - - - Modelling and laboratory investigations on freight wagon link suspensions with respect to vehicle-track dynamic interaction - - P.-AJönsson - - - - KTH - - - - -Licenciate Thesis - - - - - Experimental and theoretical analysis of freight wagon link suspension - - P.-AJönsson - - - EAndersson - - - SStichel - - - - Proceedings of the Institution of Mechanical Engineers - - 220 - 4 - - - - - Part F: Journal of Rail and Rapid Transit - - - - - Influence of link suspension characteristics variation on two-axle freight wagon dynamics - - P.-AJönsson - - - EAndersson - - - - NVSD - - 44 - 1 - - - - - - - - - New simulation model for freight wagons with UIC link suspension, VSD - - P.-AJönsson - - - SStichel - - - PerssonI - - - - 46 - - - - Suppl. 1 - - - - - Dynamics of European two-axle freight wagons - - MHoffmann - - - - Kongens Lyngby, Denmark - - - Technical University of Denmark - - -Ph.D. Thesis - - - - - Freight wagon running gears with leaf spring and ring suspension, presented at the SIMPACK user group meeting - - MStiepel - - - SZeipel - - - - - - - - - - Simulation of the Response of Leaf Springs to Broad Band Random Excitation - - DCebon - - - - Vehicle System Dynamics - - 15 - 6 - - - - - - - - - Measurement and Representation of the Mechanical Properties of Truck Leaf Springs - - PSFancher - - - RDErvin - - - CCMacadam - - - CWinkler - - - - SAE International - Warrendale, PA - - - SAE Technical Paper 800905 - - - - - On Application of the Rolling Contact Theory for Modelling of the UIC Link Suspension for Freight Wagons - - JPiotrowski - - - - Zeszyty Naukowe Instytutu Pojazdów - - 3 - 50 - - - - - - - - - A new mathematical model of the behaviour of a four-axle freight wagon with UIC single-link suspension - - JMatei - - DOI:10.1177/0954409711398173 - - - Proceedings of the Institution of Mechanical Engineers - - 225 - 637 - - - - Part F: Journal of Rail and Rapid Transit - - - - - - SVVershinsky - - - VNDanilov - - - VNChelnokov - - - II - - Wagon dynamics. Мoscow, Transport - - - 304 - - - in Russian - - - - - - BBallew - - - BJChan - - - CSandu - - Multibody dynamics modelling of the freight train bogie system Vehicle System Dynamics - - 49 - - - - - - - - Modelling friction wedges, Part II: An improved model. Proceedings of IMECE04 - - PEKlauser - - - - ASME International Mechanical Engineering Congress & Exposition - - - American Society of Mechanical Engineering - - - - - - - Freight car models and their computer-aided dynamic analysis - - RKovalev - - - NLysikov - - - GMikheev - - - DPogorelov - - - VSimonov - - - VYazykov - - - SZakharov - - - IZharov - - - IGoryacheva - - - SSoshenkov - - - ETorskaya - - - - Multibody System Dynamics - - 22 - 4 - - - - - - - - - On Calculation of Jacobian Matrices in Simulation of Multibody Systems - - DPogorelov - - - - Preprints of the NATO Advanced Study Institute on Virtual Nonlinear Multibody Systems - Schiehlen and Valasek -

Prague

- - - - - - Czech Technical University in Prague - - - - - - - Possibility of jamming and wedging in the three-piece trucks of a moving freight car - - ADMckisic - - - VFUshkalov - - - MZhechev - - - - Vehicle System Dynamics - - 45 - 1 - - - - - - - - - Dynamic models of friction wedge dampers - - JPCusumano - - - JFGardner - - - - Proceedings of the 1997 IEEE/ASME Joint Rail Conference - the 1997 IEEE/ASME Joint Rail Conference

Boston, MA

- - - - - - - - - Modelling Freight Wagon Dynamics - - MMcclanachan - - - YHandoko - - - MDhanasekar - - - DSkerman - - - JDavey - - - - Vehicle System Dynamics Supplement - - 41 - - - - - - - - - Modeling and dynamics of friction wedge dampers in railroad freight trucks Vehicle System Dynamics - - ABKaiser - - - JPCusumano - - - JFGardner - - - 38 - - - - - - - - Chaos in a railway bogie - - CHKaas-Petersen - - - - Acta Mechanica - - 61 - - - - - - - - - On non-linear methods of bogie stability assessment using computer simulations - - OPolach - - - - Proceedings of the Institution of Mechanical Engineers - - 220 - - - - - Part F: Journal of Rail and Rapid Transit - - - - - Limit cycle behaviour and chaotic motions of two-axle freight wagons with friction damping - - SStichel - - - - Multibody System Dynamics - - 8 - 3 - - - - - - - - - Dynamics of two-axle railway freight wagons with UIC standard suspension, Vehicle System Dynamics - - MHoffmann - - - HTrue - - DOI:10.1080/00423110600869594 - - - International Journal of Vehicle Mechanics and Mobility - - 44 - - - - - - - - - Analysis of the nonlinear dynamics of a 2axle freight wagon in curves, Vehicle System Dynamics - - DiGialleonardo - - - EBruni - - - STrue - - - H - - DOI:10.1080/00423114.2013.863363 - - - International Journal of Vehicle Mechanics and Mobility - - 52 - 1 - - - - - - - - - Lateral hunting stability of railway vehicles running on elastic track structures - - WMZhai - - - KYWang - - - - Journal of Computational and Nonlinear Dynamics - - 5 - 4 - - - - - ASME - - - - - Freight car curving performance in braked conditions - - ABerghuvud - - 23.DOI:10.1243/0954409021531656 - - - Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit - - 216 - - - - - - - - - <author> - <persName xmlns="http://www.tei-c.org/ns/1.0"><surname>Hecht</surname></persName> - </author> - <imprint/> - </monogr> -</biblStruct> - -<biblStruct xml:id="b66"> - <monogr> - <author> - <persName xmlns="http://www.tei-c.org/ns/1.0"><forename type="first">M</forename><surname>Keudel</surname></persName> - </author> - <author> - <persName xmlns="http://www.tei-c.org/ns/1.0"><forename type="first">J</forename></persName> - </author> - <title level="m">Verbesserte Energieeffizienz durch radialeinstellendes Fahrwerk, Eisenbahningenieur 05 - - - - - - - - - - Wheel/rail interface management in heavy haul railway operations-applying science and technology, Vehicle System Dynamics - - RDFröhling - - DOI:10.1080/00423110701413797 - - - International Journal of Vehicle Mechanics and Mobility - - 45 - 7-8 - - - - - - - - - Minimising wheel wear by optimising the primary suspension stiffness and centre plate friction of selfsteering bogies, Vehicle System Dynamics - - SNFergusson - - - RDFröhling - - - HKlopper - - DOI:10.1080/00423110801993094 - - - International Journal of Vehicle Mechanics and Mobility - - 46 - S1 - - - - - - - - - Influence of switches and crossings on wheel profile evolution in freight vehicles. Vehicle System Dynamics - - CCasanueva - - - EDoulgerakis - - - P.-AJönsson - - - SStichel - - DOI:10.1080/00423114.2014.898779 - - - International Journal of Vehicle Mechanics and Mobility - - 52 - - - - - - - - A parametric study of the effects of freight vehicles on rolling contact fatigue of rail - - JTunna - - - CUrban - - DOI:10.1243/09544097JRRT228 - - - Proceedings of the Institution of Mechanical Engineers - - 223 - 141 - - - - Part F: Journal of Rail and Rapid Transit - - - - - Whole life rail model application and development for RSSBdevelopment of an RCF damage parameter - - MBurstow - - AEATR-ES-2003-832 - - - - Rail Safety & Standards Board - - 1 - - - - - - - - Wheel damage on the Swedish iron ore line investigated via multibody simulation - - HosseinNia - - - SJönsson - - - P.-AStichel - - - S - - 228:652.DOI:10.1177/0954409714523264 - - - Proceedings of the Institution of Mechanical Engineers - the Institution of Mechanical Engineers - - - - - - - - - The dynamic effects of conventional freight car running over a dipped joint - - RVDukkipati - - - RDong - - - - Vehicle System Dynamics - - 31 - - - - - - - - - A test rig for measuring three piece bogie dynamic parameters applied to freight car application Vehicle System Dynamics 44 supplement - - LHRen - - - GShen - - - YSHu - - - - - - - - - - - - AHWickens - - The dynamics of railway vehicles on straight track-fundamental considerations of lateral stability Proceedings of the Institution of Mechanical Engineers Part - - 29 - - - - - - - - Suspension design for high performance two-axle freight vehicles Proceedings of the Institution of Mechanical Engineers Part - - AHWickens - - - AOGilchrist - - - AE WHobbs - - 3D 1969-70 - - 184 - - - - - - - - Tracking truck - - HBWebber - - - - 339466230 - - - - - - - Uklad zawieszenia pojazdu kolejowego, zwlaszcza dwuosiowego wagonu towarowego - - GreenbrierEurope - - - WagonySwidnica - - - SA - - - - PL 207920 B1 B61F 5/30 (2006.01 - - - - - Advances in Rail Wagon Design' Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit - - MEtwell - - - - 204 - - - - - - - - Association of American Railroads. Manual of standards and recommended practices. Section C-part II. Design, fabrication, and construction of freight cars - - - - - - - Chapter 11: Service worthiness tests and analyses for new freight cars - - M-1001 - - - - 374 - - - - - - - Association of American Railroads. Manual of standards and recommended practices. Section D. Trucks and truck details Specification M-976 Truck performance for rail cars - - - - - - - - - Comparison of different types of friction wedge suspensions in freight wagons - - AOrlova - - - ERudakova - - - - Proceedings of the 8-th International Conference on Railway Bogies and Running Gears - the 8-th International Conference on Railway Bogies and Running Gears

Budapest: BUTE

- - - - - - - - - - Influence of bogie to car body connection parameters on stability and curving of freight vehicle // Extended abstracts 6th international conference Railway bogies and running gears - - BoronenkoPYu - - - AMOrlova - - - - - Budapest: BUTE - - - - - - - Shear Stiffner Linkages for Radial Bogies - - HScheffel - - - PHSmit - - - - 27 - - - Supplement to Vehicle System Dynamics - - - - - The influence of inter-axle linkages on stability and guidance of freight bogies - - BoronenkoPYu - - - - Proceedings of the 8-th mini conference on vehicle system dynamics, identification and anomalies - the 8-th mini conference on vehicle system dynamics, identification and anomalies

Budapest: BUTE

- - - - - - - - - - Suspension of freight wagon bogiewith the Lenoir friction damper ensuring low wear of wheels and good lateral dynamics of the wagon - - JPiotrowski - - - PPazdzierniak - - - TAdamczewski - - - - Proc. of XVIII conference 'Pojazdy Szynow - of XVIII conference 'Pojazdy Szynow - - - I - - - - - - - - Wear and energy-saving freight bogie designs with rubber primary springs: principles and experiences - - MHecht - - - - JRRT - - 227 - - - - - - - - - Innovative Freight Wagons-A Precondition to increase the MarketShare of Rail Freight - - MHecht - - - - Archives of Transport - - 29 - - - - - Polish Academy of Sciences, committee of Transport - - - - - A new design approach for railway vehicle suspension; Rail International - - HScheffel - - 1974. - -№10.-P. 638-651 - - - - - - - Project INFRA-RADIAL-bogies for axle loads of 25 t-test and simulation'; XXI Century Rolling Stock: Ideas, Requirements, Projects Conference - - WKik - - - DScholdan - - - JStephanides - - - - St. Petersburg - - - - - - - Simulation of longitudinal dynamics of long freight trains in positioning operations Vehicle System Dynamics - - ZQi - - - ZHuang - - - XKong - - - 50 - - - - - - - - Numerical and experimental approach for the evaluation of severe longitudinal dynamics of heavy freight trains Vehicle System Dynamics - - PBelforte - - - FCeli - - - GDiana - - - SMelzi - - - - 46 - - - - Supplement - - - - - Longitudinal train dynamics' in Handbook of Railway Vehicle Dynamics - - CCole - - - - - - Iwnicki ed Taylor and Francis - - - - - An investigation of the effect of bogie and wagon pitch associated with longitudinal train dynamics - - MMcclanachan - - - CCole - - - DRoach - - - BScown - - - - The dynamics of vehicles on roads and on tracks Vehicle System Dynamics Supplement Swets & Zeitlinger Amsterdam - - - - - - - - - - Recent advancements in bluff and draft testing techniques - - MEl-Sibaie - - - - Fifth International Heavy Haul Conference -

Beijing

- - - - - - - - - White Paper Innovative Rail Freight Wagon 2030 - - RKoenig - - - MHecht - - - - - TU Dresden TU Berlin - - - - - - - - - On the Theory of Nonlinear Dynamics and its Applications in Vehicle Systems Dynamics - - HTrue - - - - Vehicle System Dynamics - - 31 - 5-6 - - - - - - - - - Numerical simulation of wheel wear evolution for heavy haul railway - - PWang - - - LGao - - DOI:10.1007/s11771-015-2510-1 - - - J. Cent. South Univ - - 22 - - - - - - - -

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+ + + + A world of individuals + + NGoodman + + + + Problems and projects + + 1972 + + + + Goodman, N. (1972). A world of individuals. In Problems and projects (pp. 155–172). Bobs-Merrill company. + + + + + Implicit definition sustained + + WV OQuine + + + + The ways of paradox and other essays +

Cambridge, MA

+ + Harvard University Press + 1976b + + + + Quine, W. V. O. (1976b). Implicit definition sustained. In The ways of paradox and other essays (2. enlarged and revised ed., pp. 133–136). Cambridge, MA: Harvard University Press. + + + + + On some difficulties in the theory of transfinite numbers and order types + + BRussell + + + 1906 + Proceedings of London Mathematical Society + 4 + + + + Russell, B. (1906). On some difficulties in the theory of transfinite numbers and order types. Proceedings of London Mathematical Society, 4, 29–53. + + + +

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+ + + + E-commerce: the challenge for UK SMEs in the twenty-first century + + MQuayle + + + + International Journal of Operations and Production Management + + 22 + 10 + + + + + + + + + Evolution, challenges and path forward for low temperature combustion engines + + AKAgarwal + + + APSingh + + + RKMaurya + + + + Progress in Energy and Combustion Science + + 61 + + + + + + + + + Thrombotic complications of central venous cath- eters in cancer patients + + DJKutter + + + + Oncologist + + 9 + + + + + + + + + + KUhlířová + + + MDrumbl + + Actors and Law Making in International Environmental Law + + MFitzmaurice + MBrus + PMerkouris + +

Cheltenham

+ + Edward Elgar Publishing + + 50 + + + The Research Handbook on International Environmental Law + + + + + Self as- sembly protein systems: Microbial S-layers + + UBSleytr + + + MSára + + + DPum + + + BSchuster + + + PMessner + + + CSchäffer + + + + Biopolymers + A. Steinbüchel and S. Fahnestock + + 7 + + + Wiley-VCH + + + + + + + Self-illuminating quantum dot conjugates for in vivo imaging + + M-KSo + + + CXu + + + AMLoening + + + SSGambhir + + + JRao + + + + Nat Biotech + + 24 + + + + + + + + + Informed conditioning on clinical covariates increases power in case-control association studies + + NZaitlen + + + SLindström + + + BPasaniuc + + + MCornelis + + + GGenovese + + + SPollack + + + BIFreedman + + + + PLoS genetics + + 8 + 11 + e1003032 + + + + + + + + + KVon Grebmer + + + ASaltzman + + + EBirol + + + DWiesmann + + + NPrasai + + + SYin + + + YYohannes + + + PMenon + + + JThompson + + + ASonntag + + Global Hunger Index: The Challenge of Hidden Hunger + + + + + + + + + Isolation and characterization of serum-resistant strains ofPseudomonas aeruginosa derived from serum-sensitive parental strains + + NLSchiller + + + DRHackley + + + AMorrison + + + + Curr Microbiol + + 10 + + + + + + + + + Importin 7 and importin alpha/importin beta are nuclear import receptors for the glucocorticoid receptor + + NDFreedman + + + KRYamamoto + + + + Mol Biol Cell + + 15 + + + + + + + + + Heart failure, chronic diuretic use, and increase in mortality and hospitalization: an observational study using propensity score methods + + AAhmed + + + AHusain + + + TELove + + + GGambassi + + + LJDell’italia + + + GSFrancis + + + MGheorghiade + + + RMAllman + + + SMeleth + + + RCBourge + + 10.1093/eurheartj/ehi890 + + + + Eur Heart J + + 27 + 12 + + + + + + + + + + MichaelBass + + + + Devices, Measurements and Properties + Handbook of Optics + + McGRAW-HILL + + 2 + + + + + + + Implications of abandoned shoreline features above Glacial Lake Duluth levels along the north shore of the Superior Basin in the vicinity of the Brule River + + + Paper presented at the 13th Biennial Meeting of the American Quaternary Association +

Minneapolis

+ + + + + University of Minnesota + + + + + +

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+ + + + + + KUhlířová + + + MDrumbl + + Actors and Law Making in International Environmental Law + + MFitzmaurice + MBrus + PMerkouris + +

Cheltenham

+ + Edward Elgar Publishing + + 50 + + + The Research Handbook on International Environmental Law + + + +

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Cambridge, MA

- - Harvard University Press - 1976b - - - - Quine, W. V. O. (1976b). Implicit definition sustained. In The ways of paradox and other essays (2. enlarged and revised ed., pp. 133–136). Cambridge, MA: Harvard University Press. - - - - - On some difficulties in the theory of transfinite numbers and order types - - BRussell - - - 1906 - Proceedings of London Mathematical Society - 4 - - - - Russell, B. (1906). On some difficulties in the theory of transfinite numbers and order types. Proceedings of London Mathematical Society, 4, 29–53. - - - -

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Cheltenham

- - Edward Elgar Publishing - - 50 - - - The Research Handbook on International Environmental Law - - - -

- - - - diff --git a/tests/files/document/23b29ea36382680716be08fc71aa81bd226e8a85.tei.xml b/tests/files/document/23b29ea36382680716be08fc71aa81bd226e8a85.tei.xml new file mode 100644 index 0000000..dbc8be5 --- /dev/null +++ b/tests/files/document/23b29ea36382680716be08fc71aa81bd226e8a85.tei.xml @@ -0,0 +1,2004 @@ + + + + + + + GROBID - A machine learning software for extracting information from scholarly documents + + + + + + DYNAMICS OF RAILWAY FREIGHT VEHICLES + + + + + 2015 + + + + + + SOriginal Citation Iwnicki + + + SStichel + + + AOrlova + + + MHecht + + + + University of Huddersfield Repository + + + DYNAMICS OF RAILWAY FREIGHT VEHICLES + + + Dynamics of railway freight vehicles. Vehicle System Dynamics. pp. 139. ISSN 00423114 + + 2015 + + + Dynamics of railway freight vehicles + + + + + + + Freight wagon + Vehicle dynamics + Computer simulation + Rail Freight + Running Gear Design + Freight Bogies + + + +

+ + + + + +

DYNAMICS OF RAILWAY FREIGHT VEHICLES

Iwnicki S.D. 1 , Stichel S. 2 , Orlova A. 3 , Hecht M. 4

Introduction

Early developments of freight wagons

Background

UIC double link

Link suspension bogies

 the short wheelset distance in the bogie of 1.8 m.  the soft longitudinal primary suspension.

The Y25 Standard Bogie

Figure 6: A Y25 type bogie

The design has been hugely successful and Y25 type bogies are the most predominant freight bogie in Europe.

'three-piece' Freight Bogies

Computer simulation

Suspension components

Friction damping

Wagons with link suspension

Basic model of leaf spring and link suspension

Advanced simulation models

Modelling the three-piece bogie

Models of the central suspension

Models of the axle to side frame interaction

Models of the centre bowl and side bearers

The same approaches can be applied to models of the centre bowl to centre plate interaction and at the side bearers.

Stability

In a bogie vehicle basically three types of hunting motion can arise:

 Wheelset hunting where one wheelset performs the hunting motion.

 M 0  M   c Mg  

Figure 14: Generic bifurcation diagram

Curving

As indicated above simulations of the running behaviour of freight wagons in curves are often performed to investigate the risk of wheel wear and Rolling Contact Fatigue (RCF).

Vehicle Resistance

Influence of curving on wheel and rail damage phenomena

Parameter identification

Modern Developments

The British Rail HSF Bogies

Computer simulations of curving and stability were carried out with various damper configurations and on-track tests of several prototypes were undertaken

The Unitruck running gear

The 'LTF' bogie

In the 1980s British Rail Research in the UK developed a novel, track friendly bogie using passenger vehicle technology. The LTF25bogie is shown in figure 27 and is described in [79].

Figure 27: The 'LTF25' bogie

Primary suspension is through steel coil springs and secondary suspension is through rubber spring elements and hydraulic dampers.

The 'Gigabox' bogie

The Double Rubber Ring Spring (DRRS) bogie

Advances in three-piece bogies

The major drivers for advances of AAR three-piece bogies were tightening ride performance and track impact standards, such as M-1001 [79] and M-976 [80], since 2000.

Cap

Elastic element

Cage Wear resistant element

Insert

Roller

Cap

Elastic element

The Lenoir pusher spring

The RC25NT Bogie

The 'LEILA' Bogie

 to reduce the noise emissions of freight wagons;  to reduce the mass of a bogie to be under 4 t and  to reduce significantly wear and running resistance.

In addition:

The SUSTRAIL Bogie

The main scientific and technological innovations being considered for the SUSTRAIL freight vehicle are:

A benchmark vehicle has been selected based on a Y25 bogie and flat bed wagon and has been used to allow quantification of the benefits of the new design.

Longitudinal dynamics

There are several areas where longitudinal dynamics can interact with the general vehicle dynamics. These include:

Figure 1 :1Figure 1: Freight wagon from Kockums Sweden, built in 1882 [4]. +

Figure 2 :2Figure 2: UIC double link suspension. +

Figure 4 :4Figure 4:. DB bogie Type 931 [7]. +

Figure 5 :5Figure 5: DB bogie Type 665 [7]. +

Figure 9 : Friction element with spring in series.9Figure 9: Friction element with spring in series. +

Figure 12 Model for bumpstop element (∆ - clearance, - stiffness of the bumpstop)12Figure 12 Model for bumpstop element (∆-clearance,-stiffness of the bumpstop) +

Figure 15 : Procedure to find the non-linear critical speed [ 60 ].1560Figure 15: Procedure to find the non-linear critical speed [60]. +

Figure 17 .17shows attractors for two different types of freight wagons. The results are in principle quite similar to those in figure 16. +

Figure 18 Map of lateral oscillation amplitude in single wagon as function of curve radius [62].18Figure 18 Map of lateral oscillation amplitude in single wagon as function of curve radius [62]. +

Figure 24 :24Figure 24: The HSFV.1 experimental freight wagon +

Figure 25 :25Figure 25: Unitruck running gear (left) and modifications for improving curving behaviour (right). +

Figure 28 :28Figure 28: The TF25 bogie +

Figure 29 : The Gigabox bogie Figure 30 :2930Figure 29: The Gigabox bogie +

Figure 31 : The DRRS bogie and cross section31Figure 31: The DRRS bogie and cross section +

Figure 32 :32Figure 32: Split wedge (left) and spatial wedge (right). +

Figure 37 :37Figure 37: The Lenoir pusher spring +

Figure 43 : TVP2007 bogie by Tatravagónka a.s.43Figure 43: TVP2007 bogie by Tatravagónka a.s. +

Figure 44 :44Figure 44: A suspension with double Lenoir links +

Figure 47 :47Figure 47: The effect of Lenoir link angle, length and friction coefficient on the critical speed of the SUSTRAIL vehicle +

Figure 48 : Maximum vertical force on the rail for the SUSTRAIL vehicle running at 120 km/h48Figure 48: Maximum vertical force on the rail for the SUSTRAIL vehicle running at 120 km/h +

Figure 50 :50Figure 50: The prototype SUSTRAIL freight bogie + + -side frame; 2-bolster; 3-wheelset; 4-primary suspension; 5-elastic connection between sub-frames Figure 36: Scheffel HS bogie (left) and bogie retrofitted with Radial Arm design (right). + + +

+ + + + + + European freight vehicle running gear: today's position and future demands + + MHecht + + + + PartF, Journal of Rail and Rapid Transit + + 215 + + + + + Proc. Of the Inst. Of Mech. Engrs. + + + + + White Paper-Roadmap to a Single European Transport Area-Towards a competitive and resource efficient transport system + + + European Commission + + 144 + + + + COM + + + + + Freight Wagon Running Gear-a review, KTH Railway Division + + P.-AJönsson + + + + Stockholm + + + + + + + Swedish: Järnvägsfordon från Kockums), Kockums industrier +

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Anaheim (CA

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Prague

+ + + + + + Czech Technical University in Prague + + + + + + + Possibility of jamming and wedging in the three-piece trucks of a moving freight car + + ADMckisic + + + VFUshkalov + + + MZhechev + + + + Vehicle System Dynamics + + 45 + 1 + + + + + + + + + Dynamic models of friction wedge dampers + + JPCusumano + + + JFGardner + + + + Proceedings of the 1997 IEEE/ASME Joint Rail Conference + the 1997 IEEE/ASME Joint Rail Conference

Boston, MA

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Budapest: BUTE

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+ + + diff --git a/tests/files/document/example.tei.xml b/tests/files/document/example.tei.xml new file mode 100644 index 0000000..5726877 --- /dev/null +++ b/tests/files/document/example.tei.xml @@ -0,0 +1,476 @@ + + + + + + + GROBID - A machine learning software for extracting information from scholarly documents + + + + + + Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network + + + + + 2003 + + + + + + IrenaMisevičienė + + + ŽemynaMilašauskienė + + + + Institute for Biomedical Research + Institute for Biomedical Research + Kaunas University of Medicine +

+ Lithuania +

+ + + + + Kaunas University of Medicine +

+ Eiveni ų 4 + 3007 + Kaunas + Lithuania +

+ + + Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network + + + MEDICINA + + 39 + 2003 + + + 604 Correspondence to Ž. Milašauskienė, + + + + + +

Key words: health care, quality of health care services, patient satisfaction, physical environment, behavior of nurses and physicians. Summary. The aim of this study is to evaluate the changes of patients' satisfaction with health care services in Lithuanian Health Promoting Hospitals network. In a survey, which was carried out by Lithuanian Health Promoting Hospitals network, 1271 patients took part in 2000 and 1467 patients in 2002. The patient's satisfaction with health care services was evaluated using a uniform anonymous questionnaire. The patients were asked to evaluate hospital environment (neatness, cleanliness, and food quality), the quality of health personnel work (attentiveness, care, risk factors, and tests used for diagnosis and treatment) rating from 1 (very bad) to 6 (excellent). It was ascertained that, during the period between both surveys, the number of patients who evaluated the sanitary conditions in the ward as excellent and very good, increased from 49.2% to 59.9%, p<0.05. According to the data received from both surveys, the hospital food quality was rated more critically than the hospital environment. The number of patients, who noted that the food quality was satisfactory, decreased from 29.8% to 22.0%, p<0.05 within the period analyzed. However the number of patients who had a positive opinion of the health care personnel's attentiveness and help while explaining the causes and consequences of various illnesses increased. Patients' assessment of the physician work remained the same. The majority of the patients (95.1% in 2000 and 94.9% in 2002) appreciated the overall performance of the physicians, and rated it very good and excellent. The analysis of patients' satisfaction is a simple study of a constituent part of the health care service quality assessment and an objective prerequisite for the improvement of the quality of the health care services.

+ + + + + +

Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network

The increasing competition and the wish to hold out in the market conditions encourages the health care institutions to change their approach to the users of health care services and to search for new methods of creating an organized system that would be able to quickly adapt to the needs of a patient (1)(2)(3)(4). The research done in Western European countries has shown that an effective and fast response to the patients' complaints ensures that most of them will come back to the same health care institution if needed (5,6). Patient satisfaction with health care services can be rated either according to the number of received complaints or by carrying out various patients' satisfaction surveys (6). Although reducing the incidence of complaints is a good indicator of the quality of health care institution activity, it would be misleading to rely on this indicator alone. Only a small part of dissatisfied patients are moved to make a formal complaint. The majority of dissatisfied patients tend to avoid using the same health care institution again (5,6). Usually each dissatisfied patient tries to inform other clients about the unsatisfactory services provided by health care institution and they will tend to choose another service if they can. Although currently Lithuanian health care institutions perform the monitoring in pursue of gathering information on patients' expectations and their needs (7), still they do it not systematically, using nonstandardized uniform questionnaires. That is why the gathered data usually serves only for internal auditing. The results of the surveys cannot be compared with the results from the other Lithuanian health care institutions. In 2000 Lithuanian Health Promoting Hospitals (HPH) network, started the evaluation of patients' satisfaction with the quality of the services provided by these hospitals (8). Using uniform questionnaire the patients treated in the Lithuanian HPH network hospitals, were examined in 2000 and 2002.

The aim of this study is to evaluate the changes of patients' satisfaction with health care services in Lithuanian HPH network.

Material and methods

Eight Lithuanian HPH network hospitals (Kaunas University of Medicine, Kaunas Clinical Infectious, Kaunas 3 rd Clinical, Vilkaviškis, Kretinga, Prienai hospitals, Palanga Rehabilitation Hospital and Tauragė District Hospital) took part in the survey carried out in 2000 and 2002. Hospitals, according to the number of beds, were divided into small ones (>100-300 beds), medium ones (300-700 beds) and big ones (>1000 beds). The sample size in each hospital was calculated according to the number of beds; following specialized statistical tables (5% error allowed) used for sociological research, while calculating representative samples. The studies in 2000 and 2002 were fulfilled in accordance with the same methodology. The patients of each hospital filled in the questionnaire in a day. Different departments of hospitals were chosen for the research. The questionnaire was distributed to patients who were treated in different departments of hospitals (internal diseases, cardiology, neurology, endocrinology, surgery, obstetrics, gynecology and pediatrics), except the intensive therapy and psychiatry departments. The nursing administrators distributed the questionnaires in all departments of the hospitals and collected them after the patients had filled them in. The questionnaires were not distributed to the patients who were hospitalized on that day. Out of 1300 questionnaires, 1271 were filled in and returned in 2000 (the response rate -97.8%). Out of 1500 questionnaires, 1419 were filled in and returned in 2002 (the response rate -94.6%). Patients, who had examinations or surgical operations on that day, did not participate in the survey. Only a minor part of the patients refused to fill in the form (0.9% and 1.3% in 2000 and 2002 respectively).

The patients were introduced with standard questionnaires comprised of 36 questions. The first part of the questionnaire consisted of general questions (age, occupation, time of treatment in this hospital, duration of stay in hospital, hospitalized urgently or by plan). The second part of the questionnaire was related to physical environment of hospital (neatness, cleanliness, and food quality) and the third part was evaluation of the health personnel's work quality (attentiveness, care, informing about health care services, causes of the disease, and tests used for diagnosis and treatment).

Considering the fact that hospitals make efforts to create better conditions for patients during their hospitalization, a few additional questions were included in the second part of the questionnaire given in 2002. The extra questions were as follows: was the patient able to make phone calls, take shower or bath; were the established visiting hours acceptable; were there enough visual aids to help orientated oneself in the hospital; were there any problems with the non-medical staff during the patients' hospitalization.

The patients were asked to choose one of the six best-suited answers to evaluate work and activities of health personnel: very bad, bad, satisfactory, good, very good, and excellent. The received data was codified. The estimation very bad was codified as 1, bad -2, satisfactory -3, good -4, very good -5, and excellent -6. While performing the analysis of the data, the estimations very bad, bad, and satisfactory were summed up and considered as negative evaluation of the work and activities of health personnel, while the estimations good, very good, and excellent were summed up and considered as positive evaluation.

While performing a statistical analysis of the data, the means of sample indications (x) and standard deviation (sd) were calculated. A Student test (t) was used for comparing the means; a chi square criterion was used for comparing non-parametrical values. The analysis of the data was performed using a statistical SPSS program.

Results and discussion

The distribution of patients according to sex and age did not differ between the first and second surveys. More women than men took part in both questionings. In the first survey participated 65.1% (n=827) of women and 34.9% (n=444) of men, in the second -61.3% (n=764) of women and 38.7% (n=501) of men p<0.05.

According to the data of the first survey, more than a half of the patients (62.5% of men and 57.1% of women) were hospitalized urgently and the rest of the patients were hospitalized by plan. The data of the second survey showed that more patients (p<0.05) were hospitalized urgently in comparison with the first survey (71.9% of men and 70.5% of women).

The hospitalization process is one of the most important factors determining patients' satisfaction with health organizations and their services. The analysis of the data has shown that the answers of men and women to the question "how much time did they spend in the reception" did not differ. Two thirds (66.4% and 75.3%) of the participants spent less than 30 minutes in the hospital reception office, however 8.9% of the first survey participants and 6.8% of the second survey participants spent more than one hour in the reception waiting for hospitalization. The majority of the patients of both surveys (89.9% and 83.5% respectively) pointed out that the reception personnel introduced to them the rules within the hospital. Physical environment, for example, cleanliness of the air in the ward and the wards itself, silence, food quality, are very important factors determining patients' mood and the rate of healing. Due to this fact, it was very important to discover how patients evaluated their surroundings (9,10). The patients were asked to indicate, whether it was comfortable for them to take a shower or bath and to make phone calls. More than two thirds of the patients were satisfied with the existing possibility to make phone calls and to take a shower or bath (75.5% and 76.8% respectively). The majority (94.2%) of the participants of the survey pointed out that their relatives and them were very satisfied with the visiting hours. Only every tenth (12.2%) patient noted that the hospital didn't have enough visual aids to help orientate in the hospital. One tenth (9.3%) of the respondents mentioned that they had problems with the non-medical staff (lift operators, cloakroom attendants, etc.).

The number of patients, who evaluated the cleanliness of the ward as excellent and very good, increased during the analyzed period. In the first survey every second patient (49.2%) estimated the neatness in the ward excellent and very good; 44.1% evaluated it as good; 6.1% of the patients indicated that the neatness in the ward was satisfactory and 0.6% said it was bad; while in the second survey the number of patients who evaluated the cleanliness of the ward as excellent and very good increased to 59.9%; the number of patients who chose the answer good decreased to 36.4%, and satisfactory decreased to 2.7% (Fig. 1).

The data of both surveys showed that patients evaluate food quality more critically than hospital physical environment. Comparing the food quality ratings we have ascertained that the number of patients who rated the food quality as good did not change: every second patient rated the food quality as good (Fig. 2).

The number of those who rated food quality as satisfactory decreased from 29.8% to 22.0% in the second survey, p < 0.05. The number of those who rated food quality as very good, on the contrary, increased from 12.7% to 18.1%, p<0.05 (Fig. 2).

Every hospitalized person hopes to get immediate and necessary help. That is why, while evaluating the promptness of health personnel, we asked the patients to note, how fast the nurse provided them necessary help. Every tenth patient in the first (11.5%) and in the second (12.0%) surveys noted that they were attended in an instant. While comparing the data of both surveys, we established that the number of patients, who received help very quickly, increased from 33.7% to 40.7%, p<0.05. The number of patients, who chose a negative estimation (i.e. very late, not fast, or not fast enough) decreased in 2002 (Fig. 3).

In order to create a better psychological environment in the health care institution, it is very important to know, how patients assess communication skills of the health care personnel and attention paid to them. Every third patient in first survey said that nurse communication and attentiveness were good (32.9%), very good (39.6%) and excellent (17.5%). The number of those who chose the answer excellent increased to 25% and the part of those who said that it was satisfactory decreased four times, from 8.3% to 2.1% respectively, during the second survey (Fig. 4).

While informing people about healthy lifestyle, causes of diseases, it is possible to change their attitudes and even behavior in respect of their health (11). Physicians play an important role while encouraging people to lead healthier lifestyles. Due to this we compared the opinions of the patients on the activeness of the nurses while explaining the causes and consequences of diseases, the ways of healthy nutrition and taking medicines. The analysis of the data of both surveys showed that the activeness of the nurses during the analyzed period did change. The number of patients, who claimed that the nurses said nothing of the causes of their diseases, decreased from 9.6% to 5.6%, p<0.05. The activeness of nurses while explaining the rules of hospital behavior has become better. According to the data of the first survey, more than two thirds (73.3%) of the patients pointed out, that the nurses always, very often, and often explained the ways of taking medicines, suggest the best nutrition and other. During the second survey the number of such nurses increased even more: from 73.3% to 88.8%, p<0.05.

The research done in the Western European countries emphasizes that communicating with the patient, providing information on the disease and its treatment, teaching of healthy lifestyle has a big influence on the patient's satisfaction with the health care services (11)(12)(13). The results received from researches and educational programs proved that educating patients improves the outcomes of the illness, it shortens the length of hospitalization, reduces need for further hospitalizations, and it also allows to use health services more effectively (14). Due to all that the efficiency of health care services increases.

The majority of the patients stated, that the physicians had completely explained the causes of their diseases, respectively 88.3% and 88. 1 5 in 2000 and 2002. Also the majority of the patients pointed out, that the physicians had told them about their treatment and future procedures, and possible adverse reactions. The majority (87.0%) of the participants of the second survey responded that the physicians paid enough attention to them during their daily visitations. Almost all (95.9% of the first and 94.9% of the second survey) of the respondents rated the physicians' attentiveness good, very good, and excellent.

Summarizing the results of both surveys, we concluded that the majority of the respondents were satisfied with the hospitalization order in the Lithuanian HPH network hospitals and with the timely and quickly rendered assistance. The number of patients, who rated the cleanliness and order in the ward very good and excellent, increased during the analyzed period. The patients evaluate the food quality in the hospitals more critically, but it is noteworthy that according to the data gathered in the second survey, the number of patients who rated food quality very good increased. The patients started evaluate the nurse's educational activity and behavior more positively. Also the number of patients, who rated the nurses' communicating skills and work as excellent, increased. Patient satisfaction with the physicians' work and attentiveness did not change during the analyzed period. The majority of the respondents rated the physicians' activity as good, very good, and excellent. Due to the fact, that the improvement of the quality of health services is based on a premise that every job and effort can always be improved, there is a reason to hope that having examined the factors that influence patients' evaluations, in the future, there will be a possibility to raise patients' satisfaction with health care services.

Conclusions

1.Following the data of both surveys, the majority of the patients who were treated in the Health Promoting Hospitals in Lithuania assessed the physical environment of the hospital positively. The number of patients, who evaluated the cleanliness of the ward positively, increased; the number of those, who assessed the hospital food quality negatively, decreased.

2.The opinion of patients on the nurses' communication skills, attentiveness and educational activity improved.

3.The patients' evaluation of the physician's attentiveness while explaining the causes and treatment of the disease did not change. The majority of the patients, hospitalized in the Lithuanian HPH network hospitals, evaluated the physician's work positively.

4.The approved system of patient's satisfaction monitoring in Lithuanian HPH network is very simple and it is a useful tool for the management of the quality of health care in the hospital.

Fig. 1 .1The evaluation of the cleanliness in the ward in 2000 and 2002 * -p<0.05, comparing between 2000 and 2002. +

Fig. 2 .2The evaluation of the food quality in 2000 and 2002 Irena Misevičienė, Žemyna Milašauskienė MEDICINA (2003) 39 tomas, Nr. +

Fig. 3 .Fig. 4 .34The evaluation of the promptness of help in 2000 and 2002 * -p<0.05, comparing between 2000 and 2002. The evaluation of the attitude and communication of nurses in 2000 and 2002 * -p<0.05, comparing between 2000 and 2002. + MEDICINA (2003) 39 tomas, Nr. 6 + + + +

Acknowledgement.

We thank the chiefs of the Lithuanian HPH network hospitals for organizing the patient's satisfaction survey and for their active participation.

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San Francisco

+ + Jossen-Bass Publisher + + + + + 1st ed. + Waller JD. Enchanting physical comfort. In: Gerties M, Edgman-Levitan S, Daley J, Delbaro TL editors. Through the patient's eyes. 1st ed. San Francisco: Jossen-Bass Pub- lisher; 1993. p. 119-153. + + + + + Evidence on patient-doctor communication + + MSteward + + + JBBrown + + + HBoon + + + JGalajda + + + LMeredith + + + MSangster + + + + Cancer Prev Control + + 3 + + + + + Steward M, Brown JB, Boon H, Galajda J, Meredith L, Sangster M. Evidence on patient-doctor communication. Cancer Prev Control 1999; 3:25-30. + + + + + On the relationship between customer participation and satisfaction: two frameworks + + DLKellogg + + + WEYoungdahl + + + DEBowen + + + + International J of service Industry Management + + 8 + + + + + Kellogg DL, Youngdahl WE, Bowen DE. On the relation- ship between customer participation and satisfaction: two frameworks. International J of service Industry Management 1997;8:206-19. + + + + + Using patient feedback for quality improvement + + KTasa + + + RBaker + + + MMurray + + + + Quality Management in Health Care + + 8 + + + + + Tasa K, Baker R, Murray M. Using patient feedback for qua- lity improvement. Quality Management in Health Care 1996;8:206-19. + + + + + Patient satisfaction and experience with health services and quality of care + + TRZastowny + + + WCStratman + + + EHAdams + + + MLFox + + + + Quality Management in Health Care + + 3 + + + + + Zastowny TR, Stratman WC, Adams EH, Fox ML. Patient satisfaction and experience with health services and quality of care. Quality Management in Health Care 1995;3:50-61. + + + + + Pacientų buvo prašoma įvertinti ligoninės fizinę aplinką (tvarką, švarą, maisto kokybę), slaugytojų ir gydytojų darbo kokybę (rūpestingumą, d ė mesingumą, informavimą apie paslaugas, ligos priežastis, naudojamus gydymo ir diagnostikos metodus) nuo 1 (labai blogai) iki 6 (puikiai) balų. Nustatyta, kad per analizuojamą laikotarpį pacientų, teigiamai įvertinusių tvarką, švarą palatoje, padaugėjo nuo 49,2 iki 59,9 proc., p<0,05. Pirminės ir pakartotinės apklausos duomenimis, ligoninėje gaunamo maisto kokybę ligoniai vertino kritiškiau palyginti su ligoninės fizine aplinka. Per analizuojamą laikotarpį pacientų, patenkinamai įvertinusių maisto kokybę sumažėjo nuo 29,8 iki 22,0 proc., p<0,05. Pagerėjo pacientų atsiliepimai apie slaugytojų bendravimą, d ė mesingumą bei aktyvumą aiškinant apie ligos priežastis ir pasekmes, apie tai, kaip elgtis ligoninėje. Pacientų vertinimai apie gydytojų veiklą nekito. Gydytojų dėmesingumą, bendravimą ir aktyvumą aiškinant ligos priežastis dauguma (95,1 ir 94,9 proc.) įvertino labai gerai ir puikiai + + + Santrauka. Darbo tikslas. Išanalizuoti ir įvertinti pacientų, gydomų Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse, pasitenkinimo teikiamomis paslaugomis pokyčius. 2000 m. Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse atliktoje apklausoje dalyvavo 1271 pacientas + + + + + Pacientų pasitenkinimas teikiamomis paslaugomis buvo vertinamas naudojant standartizuotą anoniminę anketą. Pacientų pasitenkinimo tyrimas -tai nesudėtingas teikiamų paslaugų kokybės sudėtinės dalies tyrimas bei objektyvi prielaida paslaugų kokybei gerinti + Santrauka. Darbo tikslas. Išanalizuoti ir įvertinti pacientų, gydomų Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse, pasitenkinimo teikiamomis paslaugomis pokyčius. 2000 m. Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse atliktoje apklausoje dalyvavo 1271 pacientas, 2002 m. -1467. Pacientų pasitenkinimas teikiamomis paslaugomis buvo vertinamas naudojant standartizuotą anoniminę anketą. Pacientų buvo prašoma įvertinti ligoninės fizinę aplinką (tvarką, švarą, maisto kokybę), slaugytojų ir gydytojų darbo kokybę (rūpestingumą, d ė mesingumą, informavimą apie paslaugas, ligos priežastis, naudojamus gydymo ir diagnostikos metodus) nuo 1 (labai blogai) iki 6 (puikiai) balų. Nustatyta, kad per analizuojamą laikotarpį pacientų, teigiamai įvertinusių tvarką, švarą palatoje, padaugėjo nuo 49,2 iki 59,9 proc., p<0,05. Pirminės ir pakartotinės apklausos duomenimis, ligoninėje gaunamo maisto kokybę ligoniai vertino kritiškiau palyginti su ligoninės fizine aplinka. Per analizuojamą laikotarpį pacientų, patenkinamai įvertinusių maisto kokybę sumažėjo nuo 29,8 iki 22,0 proc., p<0,05. Pagerėjo pacientų atsiliepimai apie slaugytojų bendravimą, d ė mesingumą bei aktyvumą aiškinant apie ligos priežastis ir pasekmes, apie tai, kaip elgtis ligoninėje. Pacientų vertinimai apie gydytojų veiklą nekito. Gydytojų dėmesingumą, bendravimą ir aktyvumą aiškinant ligos priežastis dauguma (95,1 ir 94,9 proc.) įvertino labai gerai ir puikiai. Pacientų pasitenkinimo tyrimas -tai nesudėtingas teikiamų paslaugų kokybės sudėtinės dalies tyrimas bei objektyvi prielaida paslaugų kokybei gerinti. + + + +

+ + + + diff --git a/tests/files/document/plos.tei.xml b/tests/files/document/plos.tei.xml new file mode 100644 index 0000000..fe6a05a --- /dev/null +++ b/tests/files/document/plos.tei.xml @@ -0,0 +1,3080 @@ + + + + + + Towards Cost-Effective Operational Monitoring Systems for Complex Waters: Analyzing Small-Scale Coastal Processes with Optical Transmissometry + + + + + + + January 20, 2017 + + + + + + + Marta + Ramı ´rez-Pe ´rez + + + Department of Physical and Technological Oceanography + Institute of Marine Sciences (ICM-CSIC) +

+ Barcelona + Spain +

+ + + + + Rafael + Gonc ¸alves-Araujo + + + Physical Oceanography of Polar Seas + Climate Sciences Division + Phytooptics Group + Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research +

+ Bremerhaven + Germany +

+ + + + + Sonja + Wiegmann + + + Physical Oceanography of Polar Seas + Climate Sciences Division + Phytooptics Group + Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research +

+ Bremerhaven + Germany +

+ + + + + Elena + Torrecilla + + + Department of Physical and Technological Oceanography + Institute of Marine Sciences (ICM-CSIC) +

+ Barcelona + Spain +

+ + + + + Raul + Bardaji + + + Department of Physical and Technological Oceanography + Institute of Marine Sciences (ICM-CSIC) +

+ Barcelona + Spain +

+ + + + + Ru + ¨diger Ro ¨ttgers + + + Remote Sensing Department + Institute for Coastal Research + Centre for Materials and Coastal Research + Helmholtz-Zentrum Geesthacht +

+ Geesthacht, Germany +

+ + + + + Astrid + Bracher + + + Physical Oceanography of Polar Seas + Climate Sciences Division + Phytooptics Group + Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research +

+ Bremerhaven + Germany +

+ + + Institute of Environmental Physics + University of Bremen +

+ Bremen + Germany +

+ + + + + Jaume + Piera + + + Department of Physical and Technological Oceanography + Institute of Marine Sciences (ICM-CSIC) +

+ Barcelona + Spain +

+ + + Towards Cost-Effective Operational Monitoring Systems for Complex Waters: Analyzing Small-Scale Coastal Processes with Optical Transmissometry + + + + January 20, 2017 + + + 4F10689DEB84756CE82C8015951A22E5 + 10.1371/journal.pone.0170706 + Received: August 4, 2016 Accepted: January 9, 2017 + + + + + + + GROBID - A machine learning software for extracting information from scholarly documents + + + + + + +

+ The detection and prediction of changes in coastal ecosystems require a better understanding of the complex physical, chemical and biological interactions, which involves that observations should be performed continuously. + ~~For this reason, there is an increasing demand for small, simple and cost-effective in situ sensors to analyze complex coastal waters at a broad range of scales.~~ + In this context, this study seeks to explore the potential of beam attenuation spectra, c(λ), measured in situ with an advanced-technology optical transmissometer, for assessing temporal and spatial patterns in the complex estuarine waters of Alfacs Bay (NW Mediterranean) as a test site. + ~~In particular, the information contained in the spectral beam attenuation coefficient was assessed and linked with different biogeochemical variables.~~ + The attenuation at λ = 710 nm was used as a proxy for particle concentration, TSM, whereas a novel parameter was adopted as an optical indicator for chlorophyll a (Chla) concentration, based on the local maximum of c(λ) observed at the long-wavelength side of the red band Chl-a absorption peak. + In addition, since coloured dissolved organic matter (CDOM) has an important influence on the beam attenuation spectral shape and complementary measurements of particle size distribution were available, the beam attenuation spectral slope was used to analyze the CDOM content. + Results were successfully compared with optical and biogeochemical variables from laboratory analysis of collocated water samples, and statistically significant correlations were found between the attenuation proxies and the biogeochemical variables TSM, Chl-a and CDOM. + This outcome depicted the potential of high-frequency beam attenuation measurements as a simple, continuous and cost-effective approach for rapid detection of changes and patterns in biogeochemical properties in complex coastal environments. +

+ + + + + +

+ Introduction +

+ ~~Coastal regions are highly dynamic and productive ecosystems, with high ecological and economic values + [1]. +~~ + ~~They are also vulnerable areas subjected to considerable anthropogenic pressures through urban and industrial development, pollution, fisheries, agriculture and aquaculture, recreation, etc.~~ + These pressures have caused, in many cases, habitat degradation carrying serious environmental and economic consequences, such as harmful algal blooms (HABs), anoxia, accumulation of pollutants and toxins or over-exploited fisheries + [2]. + + ~~Added to this, the effects of climate change and natural hazards are threatening the capability of coastal ecosystems to support goods and valuable services + [3]. +~~ + For these reasons, increasing national and international efforts have been addressed over the last decades to establish and implement environmental strategies for preservation, conservation and sustainable use of these ecosystems. + In accordance with the requirements of the European Water Framework Directive (WFD, 2000/60/EC) and the Marine Strategy Framework Directive, new interdisciplinary research programs are successfully being carried out such as the coastal module of the Global Ocean Observing System (Coastal GOOS), the Coastal Observing System for Northern and Arctic Seas (COSYNA), the Global Earth Observations System of Systems (GEOSS) or the Marine Geological and Biological Habitat Mapping (GEOHAB). + ~~All those programs have been conceived to monitor, forecast and assess the state of coastal ecosystems, which involve integrated, multidisciplinary and multiscale observing systems.~~ + ~~Coastal environments are governed by complex physical and biogeochemical processes and thus, undergo changes over a broad range of time-space scales.~~ + ~~Continuous and routine provision of data is therefore required to assess the states of these ecosystems, detect changes in these states and evaluate their impacts + [4]. +~~ + ~~In addition, there is a demand for compact, inexpensive, stable and low power in situ sensors to enable sustainable and long-term monitoring.~~ +

+ A powerful solution to resolve in-water variability at a wide range of space and time scales is the use of in situ measurements of Inherent Optical Properties (IOPs) + [5] + [6] + [7] + [8]. + + ~~IOPs depend on the composition, morphology, and concentration of the particulate and dissolved chromophoric substances in the water and thus, can be used to estimate some water quality variables (e.g.~~ + ~~turbidity) + [9] and biogeochemical properties (e.g. +~~ + ~~Chlorophyll a and suspended matter concentrations) + [10] + [11]. +~~ + ~~Among the IOP measuring devices, transmissometers present numerous advantages due to their general availability and simplicity of both operation and data processing + [12]. +~~ + These devices have been used to estimate the concentration of the suspended material in water + [13], the composition + [11] and size distribution of particles + [14] and the particulate organic carbon + [8, + 15]. + + Furthermore, several studies have demonstrated the relationships between particulate attenuation, c p , and chlorophyll concentration (as an index of phytoplankton biomass) in oceanic waters + [16] + [17] + [18]. + + In coastal waters, c p also registers changes in inorganic, detrital, and heterotrophic particles, thus compromising its correlation with chlorophyll a (Chl-a) concentration + [18]. + + ~~Nevertheless, the correlation between both variables (i.e.~~ + ~~c p and Chl-a) still needs to be further explored.~~ +

+ ~~Recent technological advances have led to the development of high spectral resolution (i.e.~~ + ~~hyperspectral), cost-effective, compact and low power transmissometers (e.g.~~ + ~~VIPER, TriOS GmbH + [19]), which have improved the operational capabilities. +~~ + In this context, this study evaluates the potential of economically affordable and advanced-technology transmissometers to detect changes and patterns in the biogeochemical properties at high temporal and spatial resolution in complex coastal environments. + ~~In particular, we focus on the information contained in the spectral beam attenuation coefficient and explore its suitability as a qualitative proxy for different biogeochemical properties.~~ + ~~The observed patterns are analyzed in relation to the prevailing physical forcing to better understand the biophysical coupling.~~ +

+ ~~This study is focused on the microtidal estuary of Alfacs Bay (Ebro Delta, NW Mediterranean coast), using it as a test site.~~ + ~~This bay is an important shellfish production area commonly affected by HABs events, which lead to significant economic losses + [20]. +~~ + ~~For this reason, this area has been intensively monitored since 1990.~~ + Research efforts have focused on characterizing the hydrodynamics of this bay + [21] + [22] + [23] + [24] + [25], its ecology + [26] + [27] + [28] + [29] and the coupling between physical and biological processes + [30]. + + ~~However, the use of optical-based approaches in this area -which allow the assessment of fine-scaled temporal and spatial variability of water constituent characteristics-is still very limited.~~ + Only + Busch (2013) + [31] analyzed the phytoplankton dynamics in this environment using radiometric measurements, which provided useful data only in day time. + + ~~One of the main conclusions of this author was that continuous observations in Alfacs Bay are required to properly understand the rapid ecosystem dynamics.~~ +

+ Materials and Methods +

+ Study site +

+ ~~Alfacs Bay is located in the south of the Ebro River Delta (Spain), in the NW Mediterranean Sea (Fig + 1). +~~ + ~~It is a shallow estuarine bay with 11 km length, 4 km width and a maximum depth of 6.5 m.~~ + ~~It is a semi-enclosed embayment separated from the open sea by a sand barrier that leaves an opening of roughly 2.5 km width, allowing the exchange of water with the open sea.~~ + ~~The major physical forcings in the bay are wind and freshwater input, whereas tidal forcing is negligible with a maximum range of 0.25 m + [32]. +~~ + ~~The freshwater discharge is derived mainly from the rice-fields irrigation channels, located in the northern part of the Bay.~~ + ~~These channels are open from April to October or November, with an average flux rate of ca.~~ + ~~14.5 m 3 Ás −1 + [22]. +~~ + ~~The freshwater inputs induce vertical stratification, while only during strong wind events the water column is vertically mixed + [21]. +~~ + ~~Heat fluxes in the ocean-atmosphere boundary layer in summer periods contribute in addition to stratifying the water column + [33]. +~~ +

+ Field campaign +

+ ~~No specific permissions were required for the location of the field campaign, and the study did not involve endangered nor protected species.~~ + ~~Two sampling strategies were adopted to analyze both temporal and spatial patterns in Alfacs Bay in June 2013.~~ + ~~The analysis of temporal patterns was conducted from the 24 th of June at 9:30 pm for 48 hours.~~ + ~~This time series of vertical profiles was gathered from 0.5 m to 3 m depth at a fixed station located in the north-central part of the Bay (blue circle in + Fig 1). +~~ + At this station, simultaneous measurements of physical (wind and current velocities and direction, and water temperature) and optical parameters (beam attenuation and near-forward angular scattering) were conducted continuously with a vertical resolution of 0.5 m. + ~~At each depth, instruments measured for 10 minutes.~~ + ~~Thereby, each vertical profile took approximately 1 hour.~~ + Water samples were collected every 6 hours at three different depths (0.5 m, 1.5 m and 3 m) for later laboratory analysis of biogeochemical and optical parameters [Chl-a, total suspended matter (TSM), algal and non-algal particulate absorption (a ph and a nap , respectively) and coloured dissolved organic matter (CDOM) absorption]. + ~~The analysis of the spatial variability was undertaken on the 27 th of June at seven stations along the bay (red circles in + Fig 1). +~~ + At each station, measurements of physical (temperature and salinity) and optical parameters were made with a ship deployed profiling package and water samples were collected at three different depths (0.5 m, 3 m and 0.5 m above the bottom). + ~~Instruments measured for 5 minutes every 0.5 m along each depth profile.~~ +

+ ~~Physical parameters.~~ + ~~Wind data were obtained from the weather station nearby the coastline in Les Cases de Alcanar, ca. 5 km south of Alfacs Bay (Fig + 1). +~~ + Three-dimensional current velocities were measured with an upward-looking Acoustic Doppler Current Profiler (ADCP, 2MHz Aquadopp, Nortek) moored at roughly 2 m depth since the maximum depth at this station was 3.5 m. + ~~It was configured to record 10-min average data with vertical cells of about 25 cm.~~ +

+ ~~Water temperature and salinity were measured with the CTD48M (Sea&Sun Technology, Germany).~~ + ~~Unfortunately, a failure in the instrument caused the loss of the data corresponding to the temporal analysis at the fixed sampling station.~~ + ~~Temperature data provided by the multiple-parameter system LISST (Sequoia Scientific Inc.) were used instead.~~ +

+ ~~Optical measurements.~~ + ~~Spectral beam attenuation coefficient was measured with the 25-cm path length VIPER (TriOS GmbH., Germany + [19]). +~~ + It is an open-path hyperspectral transmissometer which measures the beam attenuation, c(λ), in the spectral range from 360 nm to 750 nm, with an optical resolution of 15 nm (defined by the FWHM) and an acceptance angle of 0.8˚. + ~~More detailed information about the instrument performance and validation can be found in Ramı ´rez-Pe ´rez et al. (2015) + [34]. +~~ + ~~VIPER measurements were carefully performed (i.e. on the shadow side of the ship and under calm sea surface conditions) to avoid ambient light contamination + [34]. +~~ + ~~c(λ) data were collected continuously and averaged over 5 minutes.~~ + Milli-Q water references were subtracted and data were corrected for temperature and salinity dependence of pure seawater to derive the total non-water beam attenuation spectrum, c pg (λ) + [34]. + + ~~Measurements of particle size distribution (PSD) from 1.25 μm to 250 μm were conducted with the LISST-100X (Sequoia Scientific, Inc.).~~ + ~~This instrument measures the near-forward scattering at 32 logarithmically spaced angles and the beam attenuation at 670 nm + [35]. +~~ + ~~A successfully performance analysis between the attenuation measured at 670 nm by LISST and VIPER was previously carried out + [34]. +~~ + ~~Therefore, this study focused only on the LISST scattering data to derive the particle size distribution.~~ + ~~The volume concentration, V(D), was obtained through inversion of the angular forward scattering pattern using the manufacturerprovided inversion routine.~~ + ~~The used inversion algorithm is based on a kernel matrix derived from Mie theory of scattering by spherical particles.~~ + ~~Data from the outer and inner rings were excluded from further analysis due to the instability observed in the smallest and largest size ranges + [36]. +~~ + ~~Then, the particle number distribution, N(D), was calculated from the equation:~~ +

+ NðDÞ ¼ 6 Á VðDÞ=ðpD 3 Þ + ð1Þ + +

+ ~~where D represents the diameter of a volume-equivalent sphere for the midpoint of each size class.~~ + ~~To obtain the PSD, the average number of particles in each size class was divided by the width of the class, which is denoted as N'(D).~~ + ~~Finally, the PSD was fitted to the power-law function (or Junge distribution) + [37]: +~~ +

+ N 0 ðDÞ ¼ N 0 ðD 0 Þð D D 0 Þ Àx + ð2Þ + +

+ ~~where D 0 is a reference diameter, N'(D 0 ) the differential number concentration at D 0 and ξ is the nondimensional PSD slope.~~ + ~~Laboratory analysis of water samples.~~ +

+ ~~• CDOM absorption measurements: absorbance spectra (240-600 nm) were acquired with the Aqualog fluorescence spectrometer (HORIBA JobinYvon, Germany) directly after sampling.~~ + ~~Water samples were syringe-filtered with 0.2 μm Whatman Spartan filters before analysis with 1 cm quartz cuvettes.~~ + ~~Absorbance measurements were further converted to absorption coefficient, which is used as a proxy for the CDOM content in a given water sample.~~ + ~~The Napierian absorption coefficient of CDOM at each wavelength (a λ ) was obtained from the given equation:~~ +

+ a l ðm À1 Þ ¼ ð2:303 Á A l Þ=L + ð3Þ + +

+ ~~where A λ is the absorbance at specific wavelength and L is the cuvette path length in meters.~~ +

+ ~~More detailed information about the measurement protocol can be found in Gonc ¸alves-Araujo et al. (2015) + [38]. +~~ + ~~CDOM absorption spectra, a(λ), were fitted to the following exponential function + [39]: +~~ +

+ aðlÞ ¼ aðl 0 Þ Á e ÀSðlÀl 0 Þ + ð4Þ + +

+ ~~where S represents the spectral slope and a(λ 0 ), the absorption coefficient at a reference wavelength λ 0 (443 nm in this case).~~ + ~~The function was fitted to the wavelength range from 300 to 600 nm and extrapolated to 720 nm for later analysis of CDOM contribution at longer wavelengths.~~ +

+ • Algal and non-algal particulate absorption (a ph (λ) and a nap (λ)): water samples were immediately filtered through ø 47-mm GF/F filters (pore size 0.7 μm), shock-frozen in liquid nitrogen and stored at -80˚C until analysis in the laboratory at the Alfred-Wegener-Institute. + The partition of the particulate absorption, a p (λ), into phytoplankton, a ph (λ), and non-algal absorption, a nap (λ), was performed by the filter pad technique following Ferrari and Tassan (1999) + [40]. + + ~~We used a Cary 4000 UV/VIS dual beam spectrophotometer equipped with a 150-mm integrating sphere (Varian Inc., USA) as described in Taylor et al. (2011) + [41]. +~~ + ~~The measurement procedures and data analysis were performed as detailed in Ro ¨ttgers and Gehnke (2012) + [42]. +~~ + ~~Phytoplankton absorption a ph was obtained as the difference between a p and a nap .~~ +

+ ~~• Chlorophyll a: water samples for phytoplankton pigments analysis were filtered immediately after collection through ø 25-mm Whatman GF/F filters (pore size 0.7 μm).~~ + ~~Then, filters were shock-frozen in liquid nitrogen and stored at -80˚C until analysis in the laboratory at the Alfred-Wegener-Institute.~~ + ~~The extracted pigments were analyzed using the High Performance Liquid Chromatography (HPLC) technique following the method of Barlow et al.~~ +

+ ~~(1997) + [43], with modification customized to our instruments as detailed in Taylor et al. +~~ +

+ ~~(2011) + [41]. +~~ + ~~In this study, we use the Chl-a concentration as an index of phytoplankton biomass and covarying materials (biogenic detritus).~~ +

+ • Total suspended matter concentration: TSM concentration was determined gravimetrically following Ro ¨ttgers et al. (2014) + [44] to reject potential errors associated with salt retention in the filters and loss of materials during washing and combustion + [44] + [45]. + + ~~Thereby, four different volumes of each water sample (within the range from 0.6 to 2.2 liters) were filtered immediately after collection through pre-weighed Whatman GF/F filters (ø 47 mm).~~ + ~~Afterwards, the gained mass of each filter was determined by subtracting the weight of the filter from the final weight.~~ + ~~A linear regression analysis was performed for filtered volume versus the gained mass, and the regression slope was taken as the TSM concentration value + [44]. +~~ +

+ Data and statistical analysis +

+ ~~This study explored the information contained in the beam attenuation spectrum as a proxy for different biogeochemical properties.~~ + ~~In particular, the analysis focused on three major spectral features, which are described as follow (Fig + 2): +~~ +

+ ~~• Spectral slope: it is the major spectral shape feature of the beam attenuation coefficient and is related to the particle size distribution and CDOM content + [46]. +~~ + ~~For this reason and due to the lack of in situ CDOM absorption measurements, we used the total non-water beam attenuation spectral slope to detect variations in CDOM.~~ + ~~This simplification was adopted because of the high CDOM content in Alfacs Bay + [31] and the availability of additional particle size distribution measurements. +~~ + ~~To compute this parameter, beam attenuation spectra were fitted to the power-law function + [46]: +~~ +

+ c pg ðlÞ ¼ c pg ðl r Þ Á ðl=l r Þ Àg + ð5Þ + +

+ ~~where λ r is a reference wavelength (532 nm, in our case) and γ is the power-law slope.~~ + ~~The exponent was derived by non-linear least-squares regression, with a r 2 >0.98 in all cases.~~ +

+ • Peak height associated with red band phytoplankton absorption peak: although c(λ) is typically a smoothly varying function of wavelength + [46] + [47], deviations from its theoretical behavior -associated with absorbing particles-have been reported by several authors + [48] + [49] + [50]. + + + Zaneveld and Kitchen (1995) + [48] observed step increases at the long-wavelength side of the chlorophyll absorption peaks as result of anomalous diffraction and dispersion + [51], which was called "absorption peak effects". + + ~~This local maximum is therefore expected to be related to the Chl-a content (in addition to other factors such as the particle size distribution) + [48]. +~~ + For this reason, the link between the local maximum of c(λ) and the Chl-a concentration was tested in this study, since it can provide a first estimate of phytoplankton biomass and covarying materials. + Similarly to Davis et al. (1997) + [52], who estimated the Chl-a concentration based on the red band absorption peak -a(676)-by subtracting a baseline, we computed the peak height in the red band of the beam attenuation spectrum. + + ~~However, here the local maximum was found at 685 nm (approximately 10 nm past the absorption peak, in agreement with Zaneveld and Kitchen (1995) + [48]). +~~ + ~~The attenuation at 710 nm was then subtracted from this local peak as a base value to remove the effect of particle scattering.~~ + ~~This wavelength was empirically chosen based on providing the best results (based on r 2 and RMSE as compared to collocated Chl-a data determined by HPLC at discrete samples).~~ + ~~Thereby, the peak height was computed as c pg (685)-c pg (710), which was used as a proxy for Chl-a concentration.~~ +

+ • c pg (710): At long visible wavelengths, the attenuation is assumed to be determined mostly by their scattering properties and secondarily by the particulate absorption, whereas CDOM absorption has a insignificant contribution + [15, + [53] + [54] + [55]. + + ~~For this reason, the attenuation in the red part of the visible spectrum (i.e.~~ + 660 and 670 nm) has been commonly used as proxy for suspended particle concentration, since it responds primarily to concentration and secondarily to size and nature of the particles + [56]. + + While this assumption can be considered true in open waters, it could fail for complex coastal waters with high CDOM contents, which can yield a non-negligible CDOM absorption at long wavelengths (~700 nm) (e.g. + ~~+ [57]). +~~ + ~~Nevertheless, the exponential decrease of CDOM absorption with wavelength involves that the longer the wavelength, the smaller its contribution to the beam attenuation signal.~~ +

+ ~~For this reason, this study used the beam attenuation in the NIR (concretely at 710 nm) as proxy for TSM, where the CDOM absorption influence was minimum.~~ +

+ ~~Variations in time and space of these optical parameters were analyzed by means of statistical techniques.~~ + In particular, the Kruskal-Wallis H-test was applied at 5% significance level (α = 0.05) in order to identify temporal and spatial patterns in Alfacs Bay, given that data were not normally distributed, as demonstrated by the Shapiro-Wilk test performed prior to analysis. + ~~On the other hand, since both inputs were subject to errors, a model II linear regression analysis was applied to investigate the relationships between optical parameters and biogeochemical variables.~~ + Additionally, the correlations between them were examined using nonparametric Spearman-r correlation coefficients and the associated errors were determined by means of the root mean squared error (RMSE). +

+ Results and Discussion +

+ ~~At first, the results from validating the above-mentioned beam attenuation-based proxies with laboratory-measured biogeochemical variables are presented.~~ + ~~Secondly, the temporal and spatial variability and patterns of these optical and biogeochemical parameters in Alfacs Bay are shown.~~ +

+ Validation of biogeochemical proxies +

+ ~~Attenuation at 710 nm vs. total suspended matter concentration.~~ + The comparison between the total non-water beam attenuation coefficient and the particulate and CDOM absorption at 710 nm (c pg (710), a p (710) and a CDOM (710), respectively) was performed to determine the relative contribution of the two last components to the bulk c pg (710) signal (Fig + 3a). + + ~~In all samples, a p (710) and a CDOM (710) represented a minor fraction of c pg (710), since their values were two orders of magnitude lower than c pg (710).~~ + ~~c pg (710) oscillated from 0.96 to 4.66 m -1 , whereas a p (710) and a CDOM (710) ranged from 0.0065 to 0.025 m -1 in our dataset.~~ + ~~The insignificant CDOM contribution to the attenuation signal at 710 nm, enabled to use c pg (710) as proxy for TSM.~~ + ~~Then, a model II linear regression analysis was applied to investigate the relationship between c pg (710) and TSM (Fig + 3b). +~~ + ~~The regression slope (± SD) was 0.224±0.03~~ + ~~gÁm -2 , which agreed with previous works + [53, + 54]. +~~ + In addition, although our slope was flatter, our observations were within the confidence bounds of the relationship found by + Neukermans et al. (2012) + [55] for the C-Star attenuation meter (with an acceptance angle of 1.2˚) (Fig + 3b). + + This disparity in the regression slope can be partly explained due to the different attenuation wavelength used in the relationship (670 and 710 nm in Neukermans et al. (2012) + [55] and in our study, respectively). + + ~~A significant correlation was observed between c pg (710) and TSM, with r 2 = 0.75 and RMSE = 0.49 m -1 (p<0.001).~~ +

+ ~~c pg (685) peak height vs. Chl-a concentration.~~ + A relatively good linear correlation was found between the Chl-a concentration and the non-water attenuation peak height at 685 nm, c pg (685) peak (r 2 = 0.79, RMSE = 0.014 m -1 , p<0.001, Fig + 4a). + + ~~Thereby, it is reasonable to consider c pg (685) peak as a proxy for tracking changes in Chl-a concentration.~~ + Since this peak was associated with the red-band Chl-a absorption peak due to anomalous dispersion, the linear correlation between c pg (685) peak and the laboratory-derived phytoplankton absorption at 676 nm, a ph (676), was examined (Fig + 4b). + + ~~A significant linear correlation was also obtained in this case, with r 2 = 0.68 and RMSE = 0.014 m -1 (p<0.01).~~ + In turn, the correlation between Chla concentration and a ph (676) was analyzed (r 2 = 0.83; RMSE = 0.019 m -1 ; p<0.001) and compared to the power-law fit obtained by + Bricaud et al. (1995) + [58]. + + ~~Our observations were in agreement with the function predicted by those authors (Fig + 4c). +~~ + According to + Bricaud et al. (1995) + [58], the relationship between a ph (λ) and Chl-a varied as a result of changes in packaging effect and pigment composition. + + Our proxy is therefore suspected to be affected not only by these factors but also by minor contributions associated with CDOM and non-algal particles absorption, particle size distribution or Chl-a fluorescence, which compromise the relationship found between Chl-a concentration and c pg (685) peak height. + For this reason, we recommend this approach as a qualitative proxy, since its capability to provide quantitative estimates of Chl-a concentration should be further explored with a more extensive dataset. + ~~The potential influence of Chl-a fluorescence, which could lead to a decrease in the attenuation signal around 685 nm, was not evaluated here.~~ + Nevertheless, we assumed a minor effect since Chl-a fluorescence from the light beam leads to an emission into all directions, and therefore the amount of fluorescence into the direction of the beam towards the detector can be considered insignificant. +

+ ~~Spectral slope of total non-water beam attenuation vs. a CDOM (443).~~ + The evolution of the attenuation spectral slope, the particle size distribution slope and the CDOM absorption at 443 nm was analyzed to evaluate the suitability of using c pg slope as an indicator of CDOM content. + ~~Variations in c pg slope responded mainly to changes in a CDOM (443), since both parameters exhibited a fairly similar behavior although the magnitude of these variations differed.~~ + ~~PSD slope, however, varied within a relatively narrow range (from 3.43 to 4.24), playing a smaller role in the variations observed in c pg slope (Fig + 5a). +~~ + Note that the PSD slope of the LISST and the VIPER-derived c pg slope are sensitive to different particle range given the distinct scattering angles they collect, which can contribute to the different behavior observed among both variables. + In order to test whether these variations in c pg slope were associated with changes in the magnitude of a CDOM instead of in the CDOM absorption spectral slope, S CDOM , the correlation between a CDOM (443) and S CDOM was analyzed (p<0.001). + An inverse relationship was found between both variables, which is consistent with the observations from + Helms et al. (2008) + [59] (Fig + 5b). + + ~~In contrast, no correlation was observed between S CDOM and c pg slope (p>0.1).~~ + ~~Finally, the relationship between a CDOM (443) and c pg slope showed a significant correlation (p<0.001),~~ + ~~although the coefficient of determination was not too strong (r 2 = 0.5; RMSE = 0.93).~~ + ~~This correlation was due to the high CDOM content in Alfacs Bay + [31]. +~~ + ~~For future studies, however, it is recommended to perform in situ measurements of 0.2 μm-filtered and unfiltered seawater alternatively to determine CDOM absorption separately (e.g.~~ + ~~+ [14]). +~~ +

+ Spatial variability +

+ The horizontal and vertical spatial variability of the environmental, optical and biogeochemical parameters was analyzed based on vertical profiles measured at seven stations spread in Alfacs Bay (Fig + 6a). + + The vertical profiles of temperature and salinity showed a stratified water column, with a fresher and warmer surface layer and an underlying cooler and saltier water layer (Fig 6b + and 6c). + + ~~The pycnocline was located at ~3.5m depth, consistent with previous studies + [22, + [32] + [33]. +~~ + ~~The averaged temperature and salinity gradients between surface and bottom were of ΔT = 1.33˚C and ΔS = 1.84, with maximal differences of 2.1˚C and 2.7, respectively (found in the bay mouth).~~ +

+ ~~The stratification of the water column determined the spatial variations observed in the optical properties.~~ + ~~Thereby, significant differences in the beam attenuation spectra as well as in CDOM and phytoplankton absorption spectra were found between surface and bottom water layers (i.e.~~ + ~~z 3.5 m and >3.5 m, respectively) (p<0.01)~~ + ~~(Fig + 7). +~~ + ~~Meanwhile, no noticeable differences were detected in the non-algal particulate absorption, a nap (λ) (not shown).~~ + ~~Waters below the pycnocline were characterized by a higher attenuation and phytoplankton absorption, whereas CDOM absorption was lower.~~ + ~~The shape of the particle size distribution was relatively homogeneous, although the PSD slope decreased slightly with depth (Table + 1) (p>0.05). +~~ +

+ The analysis of the spatial patterns based on c pg (λ) measurements was carried out by using the above-mentioned attenuation spectral features -c pg (710), c pg (685) peak and c pg slope-and their relationships with the underlying biogeochemistry. + ~~In general, surface waters presented steeper c pg slopes and lower values of both c pg (685) peak and c pg (710).~~ + ~~In contrast, c pg (λ) measured below the pycnocline showed the opposite behavior, although their oscillations were larger (Table + 1, + Fig 8). +~~ + Statistically significant differences (p<0.01) between surface and bottom layers were found in c pg (710) and c pg slope, which increased by 40% and decreased by 27% with depth, respectively (Table + 1, Fig + 9a). + + ~~The observed decrease in the attenuation spectral slope with depth can be associated not only with a reduction in CDOM contribution but also with resuspension events.~~ + Horizontally, except slight differences detected in the bottom layer, no significant spatial patterns were observed along the different bay regions, suggesting a horizontal homogeneity in c pg (λ) spectral features (Fig + 8). + +

+ On the other hand, the spatial variability observed in the biogeochemical parameters over the sampled transects were in agreement with the total non-water beam attenuation proxies, since noticeable differences were found between surface and bottom water layers for these as well. + ~~While TSM and Chl-a increased with depth, CDOM absorption decreased (Table + 1, Fig + 8). +~~ + ~~However, horizontal variations observed in the attenuation proxies were less pronounced than those in the biogeochemical variables (Fig + 8). +~~ +

+ Finally, the results from the laboratory-measured absorption spectra exhibited differences in optical constituents contribution between surface and bottom layers, although the averaged magnitude of the total absorption was very similar for both cases (0.82 and 0.84 m -1 , respectively) (Fig + 9a). + + ~~The spatial variations found in these variables coincided with those observed from the beam attenuation-based analysis.~~ + The ternary plot of the partitioned absorption at each sampling station showed that surface waters were characterized by a higher proportion of CDOM and lower phytoplankton absorption than the water below the pycnocline, which presented larger particulate fraction (Fig + 9b). + + ~~These observations are consistent with a previous study in the region + [31], that found similar vertical distribution of optically active constituents (i.e. +~~ + ~~Chl-a, TSM, and CDOM).~~ +

+ Temporal variability +

+ ~~The 48 hours-time series of wind data showed a clear bimodal pattern with two dominant directions, from southwest and northwest (Fig + 10a and 10b). +~~ + ~~NW winds blew for ca.~~ + ~~10-12 hours during the nighttime (from 10 pm until 9:30 am, approximately) and shifted from SE to SW during daytime.~~ + ~~The velocities reached by southern winds were 5 mÁs -1 on average, with maximum values up to 8 mÁs -1 in the evening (8:30 pm).~~ + ~~The strongest winds blew from SW from 5 pm to 10 pm.~~ + The observed wind pattern responded to the typical land breeze characterized by weak nocturnal winds (<2 mÁs -1 ) blowing from land, that reverses the direction and increases the intensity during the daytime (sea breeze) + [30, + 33]. + + A similar behavior was observed in the surface current velocities, indicating that the water circulation at the sampling station was driven by the prevailing wind (Fig + 10c). + + ~~Thereby, surface water flowed in northward direction during daytime in response to southern winds and southwards when the wind ceased during nighttime.~~ + ~~This pattern was observed within the first 2 m depth, though the velocity decreased with depth.~~ +

+ The effect of hydrodynamics on the water optical properties was analyzed for time and depth, and no significant correlations (p>0.05) between the optical properties and both the current velocity and direction were found. + ~~Thereby, the differences in the optical parameters between both prevailing flow regimes (i.e.~~ + ~~southward and northward currents) were not statistically significant (p>0.05)~~ + ~~(Fig + 11). +~~ +

+ The surface current velocity (at 0.5 m depth) was 0.1 mÁs -1 on average, with a maximum value of 0. current velocity within the time interval from 6 pm to 12 am, on June 25, in agreement with c pg (710). + Nevertheless, the magnitude of this increase differed, since c pg (710) showed a rise of 20% with respect to the mean value, whereas a 40% increase was detected for TSM concentration (Fig + 13a). + + ~~Apart from this, no similar patterns were observed between both parameters along the time series, involving no significant correlation between TSM and c pg (710) (p>0.05).~~ + ~~In contrast, significant correlations were found between Chl-a concentration and c pg (685) peak (p<0.05), as well as between CDOM absorption at 443 nm and the attenuation spectral slope (p<0.01).~~ + ~~The bimodal pattern detected in the optical proxies was also observed within the bulk analyses of Chl-a and a CDOM (443).~~ + ~~Both variables increased their magnitude during southward current conditions (i.e. from 12 am to 12 pm, approximately) (Fig 13b + and 13c). +~~ +

+ Conclusions +

+ Continuous measurements of spectral beam attenuation coefficient collected in situ with an advanced-technology transmissometer have been proven as a powerful tool to better understand the existing interactions between physical and biogeochemical variables in the complex estuarine waters of Alfacs Bay (NW Mediterranean). + ~~In particular, this approach allowed the detection of qualitative changes in the major biogeochemical variables (i.e.~~ + ~~Chl-a, TSM and CDOM) at high temporal and spatial scales in this microtidal estuary.~~ + ~~Spatial patterns observed in the biogeochemical properties were driven by the vertical stratification of the water column.~~ + ~~Accordingly, surface and bottom water layers were characterized by a different relative contribution of the major biogeochemical variables to the bulk beam attenuation.~~ + Meanwhile, observations along the 48 hours time series revealed a coupling between physical (meteorological and hydrodynamic conditions) and biogeochemical properties, since the prevailing hydrodynamic regimes determined the variations in water composition. + ~~The temporal and spatial patterns were obtained based on the spectral features of the total non-water beam attenuation coefficient and validated with laboratory results of discrete water samples (i.e.~~ + ~~biogeochemical variables and partitioned absorption coefficients).~~ + ~~Significant linear relationships were found between the non-water beam attenuation proxies and the biogeochemical variables.~~ + ~~However, for future studies, it is highly recommended to include in situ beam attenuation measurements of 0.2 μm-filtered seawater for better CDOM characterization.~~ + The proposed proxies are subject to numerous uncertainties due to several factors affecting the attenuation signal (CDOM absorption and particle characteristics such as size, shape, composition, etc., which determine their absorption and scattering properties). + ~~For this reason, the collection of discrete water samples for laboratory analysis of biogeochemical variables is required for validation purposes.~~ +

+ Our results based on a high-frequency, low power ( 3 W), compact, versatile (adaptable to different observing platforms) and cost-effective (~10000€) beam attenuation meter, as well as on a simple and rapid data processing method, have demonstrated a capability to improve the operational monitoring of coastal waters towards a better understanding of their complex physical and biogeochemical interactions. +

+ Fig 1 . + 1 + +

+ ~~Fig 1. Location map of Alfacs Bay in NW Mediterranean Sea.~~ + ~~The red star indicates the location of the weather station, whereas circles show the sampling stations for the analysis of temporal (blue circle) and spatial (red circles) patterns.~~ + ~~Map produced with Open Street Map.~~ + ~~doi:10.1371/journal.pone.0170706.g001~~ +

+ + + +

+ Fig 2 . + 2 + +

+ ~~Fig 2. Representative total non-water beam attenuation spectrum measured in Alfacs Bay in June 2013.~~ + Numbers 1-3 indicate the three spectral features used in this study as proxies for biogeochemical variables: 1 = spectral slope of c pg (λ) for CDOM absorption, 2 = c pg (685)-c pg (710) for Chl-a and 3 = c pg (710) for TSM concentration. + ~~doi:10.1371/journal.pone.0170706.g002~~ +

+ + + +

+ Fig 3 . + 3 + +

+ ~~Fig 3. (a) Comparison of c pg (710), a p (710) and a CDOM (710) along all the samples used in this study.~~ + ~~(b) Scatter plot of TSM and the attenuation at 710 nm.~~ + ~~Best fit ± 90% confidence intervals are shown in blue.~~ + ~~Black solid and dashed lines represent the 90% prediction bounds of the [TSM]-c p (670 nm) data of Neukermans et al. (2012) (for the C-Star).~~ + ~~doi:10.1371/journal.pone.0170706.g003~~ +

+ + + +

+ Fig 4 .Fig 5 .Fig 6 . + 456 + +

+ ~~Fig 4. Scatter plots of (a) Chl-a concentration and c pg (685) peak.~~ + ~~(b) Phytoplankton absorption at 676 nm, a ph (676), and c pg (685) peak.~~ + ~~(c) Chl-a concentration and a ph (676).~~ + ~~The red line represents the power-law fit proposed by Bricaud et al. (1995).~~ + ~~Blue lines are the regression line ± 90% confidence intervals.~~ + ~~doi:10.1371/journal.pone.0170706.g004~~ +

+ + + +

+ ~~doi:10.1371/journal.pone.0170706.g006~~ +

+ + +

+ Fig 7 . + 7 + +

+ ~~Fig 7. Optical properties measured at seven stations occupied in Alfacs Bay and over the water column.~~ + ~~(a) In situ measured total non-water beam attenuation spectra.~~ + ~~(b) LISST-derived size distribution for particle number.~~ + ~~(c) CDOM absorption and (d) phytoplankton absorption spectra.~~ + ~~Blue and red lines indicate measurements performed above and below the pycnocline, respectively.~~ + ~~doi:10.1371/journal.pone.0170706.g007~~ +

+ + + +

+ Table 1 . + 1 + +

+ ~~Mean and standard deviation of the non-water beam attenuation-based proxies and biogeochemical variables for waters above and below the pycnocline (i.e.~~ + ~~z 3.5 m and z > 3~~ +

+ + +

+ Fig 8 . + 8 + +

+ ~~Fig 8. Spatial distribution of proxies from non-water beam attenuation and biogeochemical variables.~~ + ~~Attenuation at 710 nm, c pg (710), vs. TSM at the (a) surface (z % 0.5 m) and (b) bottom (z % 5 m) layers of Alfacs Bay.~~ + ~~c pg (685) peak vs. Chl-a concentration at the (c) surface and (d) bottom layers.~~ + ~~c pg spectral slope vs. CDOM absorption at 443 nm at the (e) surface and (f) bottom layers.~~ + ~~Produced with Ocean Data View software [60].~~ + ~~doi:10.1371/journal.pone.0170706.g008~~ +

+ + + +

+ Fig 9 . + 9 + +

+ ~~Fig 9. Analysis of partitioned absorption data.~~ + ~~(a) Contribution of the major biogeochemical variables to the total non-water absorption coefficient at 440 nm for the two different water layers.~~ + ~~(b) Ternary plot of the partitioned absorption coefficient at 440 nm (CDOM, phytoplankton, and non-algal particles) measured at the different sampling stations in Alfacs Bay.~~ + ~~Blue and red circles correspond to water samples collected above and below the pycnocline, respectively.~~ + ~~doi:10.1371/journal.pone.0170706.g009~~ +

+ + + +

+ ~~2 mÁs -1 , coinciding with SW winds episodes (Fig 12a).~~ + ~~In relation to the hydrographical variability, water temperature showed a marked diurnal cycle (day-night), with an oscillation of 1.2˚C.~~ + ~~It ranged from 23.2˚C (registered at 4 am) to 24.4˚C, at 6 pm (Fig 12b).~~ + While no significant correlations were found between physical and optical variables, the time series of c pg (710) and particle size distribution slope were characterized by an increase in their magnitude at periods of maximum current velocities, in response to the more intense northward currents (Fig 12-a, 12-c and 12-f). + ~~In contrast, c pg (685) peak and c pg spectral slope exhibited a bimodal pattern similar to that observed for the wind and current data.~~ + ~~Both parameters rose under weak southward current conditions, whereas the minimum values concurred with the maximum current velocities flowing northwards (Fig 12-a, 12-d and 12-e).~~ + ~~The temporal variations in biogeochemical properties showed similar patterns as those observed based on c pg proxies (Fig 13).~~ + ~~The concentration of particulate matter increased with~~ +

+ + +

+ Fig 10 . + 10 + +

+ ~~Fig 10.~~ + ~~Time series of physical forcings along 48 hours.~~ + ~~(a) Wind speed and direction measured in the weather station located in Alcanar.~~ + ~~(b) Wind speed and direction (to) represented by arrows.~~ + ~~Upward pointing arrow indicates the North.~~ + ~~(c) Surface current velocity and direction represented by arrows, measured at 0.5 m depth with the ADCP located in the sampling station.~~ + ~~doi:10.1371/journal.pone.0170706.g010~~ +

+ + + +

+ Fig 11 . + 11 + +

+ ~~Fig 11.~~ + ~~Optical measurements collected during profiling along 48 hours for the analysis of temporal patterns in Alfacs Bay.~~ + ~~(a) In situ measured total non-water beam attenuation spectra.~~ + ~~(b) LISST-derived size distribution for particle number.~~ + ~~(c) CDOM absorption and (d) phytoplankton absorption spectra.~~ + ~~Blue and red lines indicate measurements performed under the influence of southward and northward currents, respectively.~~ + ~~doi:10.1371/journal.pone.0170706.g011~~ +

+ + + +

+ Fig 12 . + 12 + +

+ ~~Fig 12. Variations with time and depth in the attenuation-based proxies and PSD slope along with the current velocity.~~ + ~~(a) Temporal dataset of current velocity measured within the first 2 m depth.~~ + ~~Time series of vertical profiles of (b) water temperature, (c) c pg (710), (d) c pg (685) peak, (e) c pg spectral slope and (e) LISST-derived PSD slope.~~ + ~~doi:10.1371/journal.pone.0170706.g012~~ +

+ + + +

+ +

+ + + + PLOS ONE | DOI:10.1371/journal.pone.0170706 January 20, 2017 + + + +

+ Acknowledgments +

+ ~~We thank E. Zafra for his dedication and effort in organizing, planning and performing the field campaign.~~ + ~~We also thank to J. Ballabrera, A. Olariaga and V. Fuentes (ICM-CSIC, Spain), for their support and collaboration during the field campaign.~~ + ~~We are grateful to E. Boss and an anonymous reviewer for providing valuable comments on the manuscript.~~ +

+ Author Contributions +

+ ~~Conceptualization: MR-P RR AB JP.~~ +

+ Formal analysis: MR-P RG-A. +

+ Funding acquisition: ET AB JP. +

+ ~~Investigation: MR-P RG-A SW RB AB JP.~~ +

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+ + + diff --git a/tests/files/empty_citation.tei.xml b/tests/files/empty_citation.tei.xml deleted file mode 100644 index cb21f6e..0000000 --- a/tests/files/empty_citation.tei.xml +++ /dev/null @@ -1,6 +0,0 @@ - - - - <imprint/> - </monogr> -</biblStruct> diff --git a/tests/files/empty_citation_unstructured.tei.xml b/tests/files/empty_citation_unstructured.tei.xml deleted file mode 100644 index 35aee19..0000000 --- a/tests/files/empty_citation_unstructured.tei.xml +++ /dev/null @@ -1,7 +0,0 @@ -<biblStruct > - <monogr> - <title/> - <imprint/> - </monogr> - <note type="raw_reference">blah</note> -</biblStruct> diff --git a/tests/files/example_citation_list.xml b/tests/files/example_citation_list.xml deleted file mode 100644 index 218fa46..0000000 --- a/tests/files/example_citation_list.xml +++ /dev/null @@ -1,358 +0,0 @@ -<TEI xmlns="http://www.tei-c.org/ns/1.0" xmlns:xlink="http://www.w3.org/1999/xlink" - xmlns:mml="http://www.w3.org/1998/Math/MathML"> - <teiHeader/> - <text> - <front/> - <body/> - <back> - <div> - <listBibl> -<biblStruct xml:id="b0"> - <analytic> - <title level="a" type="main">E-commerce: the challenge for UK SMEs in the twenty-first century - - MQuayle - - - - International Journal of Operations and Production Management - - 22 - 10 - - - - - - - - - Evolution, challenges and path forward for low temperature combustion engines - - AKAgarwal - - - APSingh - - - RKMaurya - - - - Progress in Energy and Combustion Science - - 61 - - - - - - - - - Thrombotic complications of central venous cath- eters in cancer patients - - DJKutter - - - - Oncologist - - 9 - - - - - - - - - - KUhlířová - - - MDrumbl - - Actors and Law Making in International Environmental Law - - MFitzmaurice - MBrus - PMerkouris - -

Cheltenham

- - Edward Elgar Publishing - - 50 - - - The Research Handbook on International Environmental Law - - - - - Self as- sembly protein systems: Microbial S-layers - - UBSleytr - - - MSára - - - DPum - - - BSchuster - - - PMessner - - - CSchäffer - - - - Biopolymers - A. Steinbüchel and S. Fahnestock - - 7 - - - Wiley-VCH - - - - - - - Self-illuminating quantum dot conjugates for in vivo imaging - - M-KSo - - - CXu - - - AMLoening - - - SSGambhir - - - JRao - - - - Nat Biotech - - 24 - - - - - - - - - Informed conditioning on clinical covariates increases power in case-control association studies - - NZaitlen - - - SLindström - - - BPasaniuc - - - MCornelis - - - GGenovese - - - SPollack - - - BIFreedman - - - - PLoS genetics - - 8 - 11 - e1003032 - - - - - - - - - KVon Grebmer - - - ASaltzman - - - EBirol - - - DWiesmann - - - NPrasai - - - SYin - - - YYohannes - - - PMenon - - - JThompson - - - ASonntag - - Global Hunger Index: The Challenge of Hidden Hunger - - - - - - - - - Isolation and characterization of serum-resistant strains ofPseudomonas aeruginosa derived from serum-sensitive parental strains - - NLSchiller - - - DRHackley - - - AMorrison - - - - Curr Microbiol - - 10 - - - - - - - - - Importin 7 and importin alpha/importin beta are nuclear import receptors for the glucocorticoid receptor - - NDFreedman - - - KRYamamoto - - - - Mol Biol Cell - - 15 - - - - - - - - - Heart failure, chronic diuretic use, and increase in mortality and hospitalization: an observational study using propensity score methods - - AAhmed - - - AHusain - - - TELove - - - GGambassi - - - LJDell’italia - - - GSFrancis - - - MGheorghiade - - - RMAllman - - - SMeleth - - - RCBourge - - 10.1093/eurheartj/ehi890 - - - - Eur Heart J - - 27 - 12 - - - - - - - - - - MichaelBass - - - - Devices, Measurements and Properties - Handbook of Optics - - McGRAW-HILL - - 2 - - - - - - - Implications of abandoned shoreline features above Glacial Lake Duluth levels along the north shore of the Superior Basin in the vicinity of the Brule River - - - Paper presented at the 13th Biennial Meeting of the American Quaternary Association -

Minneapolis

- - - - - University of Minnesota - - - - - - - - - - diff --git a/tests/files/example_grobid.tei.xml b/tests/files/example_grobid.tei.xml deleted file mode 100644 index 5726877..0000000 --- a/tests/files/example_grobid.tei.xml +++ /dev/null @@ -1,476 +0,0 @@ - - - - - - - GROBID - A machine learning software for extracting information from scholarly documents - - - - - - Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network - - - - - 2003 - - - - - - IrenaMisevičienė - - - ŽemynaMilašauskienė - - - - Institute for Biomedical Research - Institute for Biomedical Research - Kaunas University of Medicine -

- Lithuania -

- - - - - Kaunas University of Medicine -

- Eiveni ų 4 - 3007 - Kaunas - Lithuania -

- - - Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network - - - MEDICINA - - 39 - 2003 - - - 604 Correspondence to Ž. Milašauskienė, - - - - - -

- - - - - -

Changes of patients' satisfaction with the health care services in Lithuanian Health Promoting Hospitals network

The aim of this study is to evaluate the changes of patients' satisfaction with health care services in Lithuanian HPH network.

Material and methods

Results and discussion

Conclusions

2.The opinion of patients on the nurses' communication skills, attentiveness and educational activity improved.

4.The approved system of patient's satisfaction monitoring in Lithuanian HPH network is very simple and it is a useful tool for the management of the quality of health care in the hospital.

Fig. 1 .1The evaluation of the cleanliness in the ward in 2000 and 2002 * -p<0.05, comparing between 2000 and 2002. -

Fig. 2 .2The evaluation of the food quality in 2000 and 2002 Irena Misevičienė, Žemyna Milašauskienė MEDICINA (2003) 39 tomas, Nr. -

Acknowledgement.

We thank the chiefs of the Lithuanian HPH network hospitals for organizing the patient's satisfaction survey and for their active participation.

- -

- - - - - - National survey of hospital patients - - SBruster - - - BJarmen - - - NBosanquet - - - DWeston - - - RErens - - - TLDelbanco - - - - BMJ - - 10 - - - - - Bruster S, Jarmen B, Bosanquet N, Weston D, Erens R, Delbanco TL. National survey of hospital patients. BMJ 1994; 10:1542-6. - - - - - Innovation in patient-centred education - - BEller - - - MGerties - - - SEdgman-Levitan - - - JDaley - - - TLDelbaro - - - - Through the patient's eyes -

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- - Jossen-Bass Publisher - - - - 1st ed - Healy J, Mckee M. Monit. In: Gerties M, Edgman-Levitan S, Daley J, Delbaro TL, editors. Through the patient's eyes.1st ed. San Francisco: Jossen-Bass Publisher; 1993. - - - - - Integrated quality development in public healthcare - - JOvretveit - - - - Norwegian Medical Association - - 128 - - - - Ovretveit J. Integrated quality development in public health- care. Norwegian Medical Association, Oslo, Norway; 1999. p. 128. - - - - - Medical participation in and leadership of quality programmes - - JOvretveit - - - - J of Management in medicine - - 10 - 5 - - - - - Ovretveit J. Medical participation in and leadership of quality programmes. J of Management in medicine 1996;10(5):21- 9. - - - - - Pacientų poreikių bei nuomonės apie teikiamas sveikatos priežiūros paslaugas vertinimas. (Assessment of patients' needs and opinion on health care services.) Nacionalinės sveikatos tarybos metinis praneš imas - - EŽebienė - - - IMisevičienė - - - ZMilašauskienė - - - - - - - Žebienė E, Misevičienė I, Milašauskienė Z. Pacientų poreikių bei nuomonės apie teikiamas sveikatos priežiūros paslaugas vertinimas. (Assessment of patients' needs and opinion on health care services.) Nacionalinės sveikatos tarybos metinis praneš imas 2001; 87-90. - - - - - Pacientų pasitenkinimas ligoninės medicinos personalo darbu. (Patients' satisfaction with the work of medical staff of hospital) - - IMisevičiene - - - ŽMilašauskienė - - - - Medicina (Kaunas - - 38 - 5 - - - - - Misevičiene I, Milašauskienė Ž. Pacientų pasitenkinimas ligoninės medicinos personalo darbu. (Patients' satisfaction with the work of medical staff of hospital). Medicina (Kau- nas) 2002;38(5):559-65. - - - - - Patient satisfaction: a customer service approach - - JMarr - - - MGreengarten - - - - Health Manage Forum - - 8 - 3 - - - - - Marr J, Greengarten M. Patient satisfaction: a customer service approach. Health Manage Forum 1995;8(3):52-6. - - - - - Enchanting physical comfort - - JDWaller - - - MGerties - - - SEdgman-Levitan - - - JDaley - - - TLDelbaro - - - - Through the patient's eyes -

San Francisco

- - Jossen-Bass Publisher - - - - - 1st ed. - Waller JD. Enchanting physical comfort. In: Gerties M, Edgman-Levitan S, Daley J, Delbaro TL editors. Through the patient's eyes. 1st ed. San Francisco: Jossen-Bass Pub- lisher; 1993. p. 119-153. - - - - - Evidence on patient-doctor communication - - MSteward - - - JBBrown - - - HBoon - - - JGalajda - - - LMeredith - - - MSangster - - - - Cancer Prev Control - - 3 - - - - - Steward M, Brown JB, Boon H, Galajda J, Meredith L, Sangster M. Evidence on patient-doctor communication. Cancer Prev Control 1999; 3:25-30. - - - - - On the relationship between customer participation and satisfaction: two frameworks - - DLKellogg - - - WEYoungdahl - - - DEBowen - - - - International J of service Industry Management - - 8 - - - - - Kellogg DL, Youngdahl WE, Bowen DE. On the relation- ship between customer participation and satisfaction: two frameworks. International J of service Industry Management 1997;8:206-19. - - - - - Using patient feedback for quality improvement - - KTasa - - - RBaker - - - MMurray - - - - Quality Management in Health Care - - 8 - - - - - Tasa K, Baker R, Murray M. Using patient feedback for qua- lity improvement. Quality Management in Health Care 1996;8:206-19. - - - - - Patient satisfaction and experience with health services and quality of care - - TRZastowny - - - WCStratman - - - EHAdams - - - MLFox - - - - Quality Management in Health Care - - 3 - - - - - Zastowny TR, Stratman WC, Adams EH, Fox ML. Patient satisfaction and experience with health services and quality of care. Quality Management in Health Care 1995;3:50-61. - - - - - Pacientų buvo prašoma įvertinti ligoninės fizinę aplinką (tvarką, švarą, maisto kokybę), slaugytojų ir gydytojų darbo kokybę (rūpestingumą, d ė mesingumą, informavimą apie paslaugas, ligos priežastis, naudojamus gydymo ir diagnostikos metodus) nuo 1 (labai blogai) iki 6 (puikiai) balų. Nustatyta, kad per analizuojamą laikotarpį pacientų, teigiamai įvertinusių tvarką, švarą palatoje, padaugėjo nuo 49,2 iki 59,9 proc., p<0,05. Pirminės ir pakartotinės apklausos duomenimis, ligoninėje gaunamo maisto kokybę ligoniai vertino kritiškiau palyginti su ligoninės fizine aplinka. Per analizuojamą laikotarpį pacientų, patenkinamai įvertinusių maisto kokybę sumažėjo nuo 29,8 iki 22,0 proc., p<0,05. Pagerėjo pacientų atsiliepimai apie slaugytojų bendravimą, d ė mesingumą bei aktyvumą aiškinant apie ligos priežastis ir pasekmes, apie tai, kaip elgtis ligoninėje. Pacientų vertinimai apie gydytojų veiklą nekito. Gydytojų dėmesingumą, bendravimą ir aktyvumą aiškinant ligos priežastis dauguma (95,1 ir 94,9 proc.) įvertino labai gerai ir puikiai - - - Santrauka. Darbo tikslas. Išanalizuoti ir įvertinti pacientų, gydomų Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse, pasitenkinimo teikiamomis paslaugomis pokyčius. 2000 m. Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse atliktoje apklausoje dalyvavo 1271 pacientas - - - - - Pacientų pasitenkinimas teikiamomis paslaugomis buvo vertinamas naudojant standartizuotą anoniminę anketą. Pacientų pasitenkinimo tyrimas -tai nesudėtingas teikiamų paslaugų kokybės sudėtinės dalies tyrimas bei objektyvi prielaida paslaugų kokybei gerinti - Santrauka. Darbo tikslas. Išanalizuoti ir įvertinti pacientų, gydomų Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse, pasitenkinimo teikiamomis paslaugomis pokyčius. 2000 m. Lietuvos sveikatą stiprinančių ligoninių tinklo ligoninėse atliktoje apklausoje dalyvavo 1271 pacientas, 2002 m. -1467. Pacientų pasitenkinimas teikiamomis paslaugomis buvo vertinamas naudojant standartizuotą anoniminę anketą. Pacientų buvo prašoma įvertinti ligoninės fizinę aplinką (tvarką, švarą, maisto kokybę), slaugytojų ir gydytojų darbo kokybę (rūpestingumą, d ė mesingumą, informavimą apie paslaugas, ligos priežastis, naudojamus gydymo ir diagnostikos metodus) nuo 1 (labai blogai) iki 6 (puikiai) balų. Nustatyta, kad per analizuojamą laikotarpį pacientų, teigiamai įvertinusių tvarką, švarą palatoje, padaugėjo nuo 49,2 iki 59,9 proc., p<0,05. Pirminės ir pakartotinės apklausos duomenimis, ligoninėje gaunamo maisto kokybę ligoniai vertino kritiškiau palyginti su ligoninės fizine aplinka. Per analizuojamą laikotarpį pacientų, patenkinamai įvertinusių maisto kokybę sumažėjo nuo 29,8 iki 22,0 proc., p<0,05. Pagerėjo pacientų atsiliepimai apie slaugytojų bendravimą, d ė mesingumą bei aktyvumą aiškinant apie ligos priežastis ir pasekmes, apie tai, kaip elgtis ligoninėje. Pacientų vertinimai apie gydytojų veiklą nekito. Gydytojų dėmesingumą, bendravimą ir aktyvumą aiškinant ligos priežastis dauguma (95,1 ir 94,9 proc.) įvertino labai gerai ir puikiai. Pacientų pasitenkinimo tyrimas -tai nesudėtingas teikiamų paslaugų kokybės sudėtinės dalies tyrimas bei objektyvi prielaida paslaugų kokybei gerinti. - - - -

- - - - diff --git a/tests/files/example_grobid_plos.tei.xml b/tests/files/example_grobid_plos.tei.xml deleted file mode 100644 index fe6a05a..0000000 --- a/tests/files/example_grobid_plos.tei.xml +++ /dev/null @@ -1,3080 +0,0 @@ - - - - - - Towards Cost-Effective Operational Monitoring Systems for Complex Waters: Analyzing Small-Scale Coastal Processes with Optical Transmissometry - - - - - - - January 20, 2017 - - - - - - - Marta - Ramı ´rez-Pe ´rez - - - Department of Physical and Technological Oceanography - Institute of Marine Sciences (ICM-CSIC) -

- Barcelona - Spain -

- - - - - Rafael - Gonc ¸alves-Araujo - - - Physical Oceanography of Polar Seas - Climate Sciences Division - Phytooptics Group - Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research -

- Bremerhaven - Germany -

- - - - - Sonja - Wiegmann - - - Physical Oceanography of Polar Seas - Climate Sciences Division - Phytooptics Group - Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research -

- Bremerhaven - Germany -

- - - - - Elena - Torrecilla - - - Department of Physical and Technological Oceanography - Institute of Marine Sciences (ICM-CSIC) -

- Barcelona - Spain -

- - - - - Raul - Bardaji - - - Department of Physical and Technological Oceanography - Institute of Marine Sciences (ICM-CSIC) -

- Barcelona - Spain -

- - - - - Ru - ¨diger Ro ¨ttgers - - - Remote Sensing Department - Institute for Coastal Research - Centre for Materials and Coastal Research - Helmholtz-Zentrum Geesthacht -

- Geesthacht, Germany -

- - - - - Astrid - Bracher - - - Physical Oceanography of Polar Seas - Climate Sciences Division - Phytooptics Group - Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research -

- Bremerhaven - Germany -

- - - Institute of Environmental Physics - University of Bremen -

- Bremen - Germany -

- - - - - Jaume - Piera - - - Department of Physical and Technological Oceanography - Institute of Marine Sciences (ICM-CSIC) -

- Barcelona - Spain -

- - - Towards Cost-Effective Operational Monitoring Systems for Complex Waters: Analyzing Small-Scale Coastal Processes with Optical Transmissometry - - - - January 20, 2017 - - - 4F10689DEB84756CE82C8015951A22E5 - 10.1371/journal.pone.0170706 - Received: August 4, 2016 Accepted: January 9, 2017 - - - - - - - GROBID - A machine learning software for extracting information from scholarly documents - - - - - - -

- The detection and prediction of changes in coastal ecosystems require a better understanding of the complex physical, chemical and biological interactions, which involves that observations should be performed continuously. - ~~For this reason, there is an increasing demand for small, simple and cost-effective in situ sensors to analyze complex coastal waters at a broad range of scales.~~ - In this context, this study seeks to explore the potential of beam attenuation spectra, c(λ), measured in situ with an advanced-technology optical transmissometer, for assessing temporal and spatial patterns in the complex estuarine waters of Alfacs Bay (NW Mediterranean) as a test site. - ~~In particular, the information contained in the spectral beam attenuation coefficient was assessed and linked with different biogeochemical variables.~~ - The attenuation at λ = 710 nm was used as a proxy for particle concentration, TSM, whereas a novel parameter was adopted as an optical indicator for chlorophyll a (Chla) concentration, based on the local maximum of c(λ) observed at the long-wavelength side of the red band Chl-a absorption peak. - In addition, since coloured dissolved organic matter (CDOM) has an important influence on the beam attenuation spectral shape and complementary measurements of particle size distribution were available, the beam attenuation spectral slope was used to analyze the CDOM content. - Results were successfully compared with optical and biogeochemical variables from laboratory analysis of collocated water samples, and statistically significant correlations were found between the attenuation proxies and the biogeochemical variables TSM, Chl-a and CDOM. - This outcome depicted the potential of high-frequency beam attenuation measurements as a simple, continuous and cost-effective approach for rapid detection of changes and patterns in biogeochemical properties in complex coastal environments. -

- - - - - -

- Introduction -

- ~~Coastal regions are highly dynamic and productive ecosystems, with high ecological and economic values - [1]. -~~ - ~~They are also vulnerable areas subjected to considerable anthropogenic pressures through urban and industrial development, pollution, fisheries, agriculture and aquaculture, recreation, etc.~~ - These pressures have caused, in many cases, habitat degradation carrying serious environmental and economic consequences, such as harmful algal blooms (HABs), anoxia, accumulation of pollutants and toxins or over-exploited fisheries - [2]. - - ~~Added to this, the effects of climate change and natural hazards are threatening the capability of coastal ecosystems to support goods and valuable services - [3]. -~~ - For these reasons, increasing national and international efforts have been addressed over the last decades to establish and implement environmental strategies for preservation, conservation and sustainable use of these ecosystems. - In accordance with the requirements of the European Water Framework Directive (WFD, 2000/60/EC) and the Marine Strategy Framework Directive, new interdisciplinary research programs are successfully being carried out such as the coastal module of the Global Ocean Observing System (Coastal GOOS), the Coastal Observing System for Northern and Arctic Seas (COSYNA), the Global Earth Observations System of Systems (GEOSS) or the Marine Geological and Biological Habitat Mapping (GEOHAB). - ~~All those programs have been conceived to monitor, forecast and assess the state of coastal ecosystems, which involve integrated, multidisciplinary and multiscale observing systems.~~ - ~~Coastal environments are governed by complex physical and biogeochemical processes and thus, undergo changes over a broad range of time-space scales.~~ - ~~Continuous and routine provision of data is therefore required to assess the states of these ecosystems, detect changes in these states and evaluate their impacts - [4]. -~~ - ~~In addition, there is a demand for compact, inexpensive, stable and low power in situ sensors to enable sustainable and long-term monitoring.~~ -

- A powerful solution to resolve in-water variability at a wide range of space and time scales is the use of in situ measurements of Inherent Optical Properties (IOPs) - [5] - [6] - [7] - [8]. - - ~~IOPs depend on the composition, morphology, and concentration of the particulate and dissolved chromophoric substances in the water and thus, can be used to estimate some water quality variables (e.g.~~ - ~~turbidity) - [9] and biogeochemical properties (e.g. -~~ - ~~Chlorophyll a and suspended matter concentrations) - [10] - [11]. -~~ - ~~Among the IOP measuring devices, transmissometers present numerous advantages due to their general availability and simplicity of both operation and data processing - [12]. -~~ - These devices have been used to estimate the concentration of the suspended material in water - [13], the composition - [11] and size distribution of particles - [14] and the particulate organic carbon - [8, - 15]. - - Furthermore, several studies have demonstrated the relationships between particulate attenuation, c p , and chlorophyll concentration (as an index of phytoplankton biomass) in oceanic waters - [16] - [17] - [18]. - - In coastal waters, c p also registers changes in inorganic, detrital, and heterotrophic particles, thus compromising its correlation with chlorophyll a (Chl-a) concentration - [18]. - - ~~Nevertheless, the correlation between both variables (i.e.~~ - ~~c p and Chl-a) still needs to be further explored.~~ -

- ~~Recent technological advances have led to the development of high spectral resolution (i.e.~~ - ~~hyperspectral), cost-effective, compact and low power transmissometers (e.g.~~ - ~~VIPER, TriOS GmbH - [19]), which have improved the operational capabilities. -~~ - In this context, this study evaluates the potential of economically affordable and advanced-technology transmissometers to detect changes and patterns in the biogeochemical properties at high temporal and spatial resolution in complex coastal environments. - ~~In particular, we focus on the information contained in the spectral beam attenuation coefficient and explore its suitability as a qualitative proxy for different biogeochemical properties.~~ - ~~The observed patterns are analyzed in relation to the prevailing physical forcing to better understand the biophysical coupling.~~ -

- ~~This study is focused on the microtidal estuary of Alfacs Bay (Ebro Delta, NW Mediterranean coast), using it as a test site.~~ - ~~This bay is an important shellfish production area commonly affected by HABs events, which lead to significant economic losses - [20]. -~~ - ~~For this reason, this area has been intensively monitored since 1990.~~ - Research efforts have focused on characterizing the hydrodynamics of this bay - [21] - [22] - [23] - [24] - [25], its ecology - [26] - [27] - [28] - [29] and the coupling between physical and biological processes - [30]. - - ~~However, the use of optical-based approaches in this area -which allow the assessment of fine-scaled temporal and spatial variability of water constituent characteristics-is still very limited.~~ - Only - Busch (2013) - [31] analyzed the phytoplankton dynamics in this environment using radiometric measurements, which provided useful data only in day time. - - ~~One of the main conclusions of this author was that continuous observations in Alfacs Bay are required to properly understand the rapid ecosystem dynamics.~~ -

- Materials and Methods -

- Study site -

- ~~Alfacs Bay is located in the south of the Ebro River Delta (Spain), in the NW Mediterranean Sea (Fig - 1). -~~ - ~~It is a shallow estuarine bay with 11 km length, 4 km width and a maximum depth of 6.5 m.~~ - ~~It is a semi-enclosed embayment separated from the open sea by a sand barrier that leaves an opening of roughly 2.5 km width, allowing the exchange of water with the open sea.~~ - ~~The major physical forcings in the bay are wind and freshwater input, whereas tidal forcing is negligible with a maximum range of 0.25 m - [32]. -~~ - ~~The freshwater discharge is derived mainly from the rice-fields irrigation channels, located in the northern part of the Bay.~~ - ~~These channels are open from April to October or November, with an average flux rate of ca.~~ - ~~14.5 m 3 Ás −1 - [22]. -~~ - ~~The freshwater inputs induce vertical stratification, while only during strong wind events the water column is vertically mixed - [21]. -~~ - ~~Heat fluxes in the ocean-atmosphere boundary layer in summer periods contribute in addition to stratifying the water column - [33]. -~~ -

- Field campaign -

- ~~No specific permissions were required for the location of the field campaign, and the study did not involve endangered nor protected species.~~ - ~~Two sampling strategies were adopted to analyze both temporal and spatial patterns in Alfacs Bay in June 2013.~~ - ~~The analysis of temporal patterns was conducted from the 24 th of June at 9:30 pm for 48 hours.~~ - ~~This time series of vertical profiles was gathered from 0.5 m to 3 m depth at a fixed station located in the north-central part of the Bay (blue circle in - Fig 1). -~~ - At this station, simultaneous measurements of physical (wind and current velocities and direction, and water temperature) and optical parameters (beam attenuation and near-forward angular scattering) were conducted continuously with a vertical resolution of 0.5 m. - ~~At each depth, instruments measured for 10 minutes.~~ - ~~Thereby, each vertical profile took approximately 1 hour.~~ - Water samples were collected every 6 hours at three different depths (0.5 m, 1.5 m and 3 m) for later laboratory analysis of biogeochemical and optical parameters [Chl-a, total suspended matter (TSM), algal and non-algal particulate absorption (a ph and a nap , respectively) and coloured dissolved organic matter (CDOM) absorption]. - ~~The analysis of the spatial variability was undertaken on the 27 th of June at seven stations along the bay (red circles in - Fig 1). -~~ - At each station, measurements of physical (temperature and salinity) and optical parameters were made with a ship deployed profiling package and water samples were collected at three different depths (0.5 m, 3 m and 0.5 m above the bottom). - ~~Instruments measured for 5 minutes every 0.5 m along each depth profile.~~ -

- ~~Physical parameters.~~ - ~~Wind data were obtained from the weather station nearby the coastline in Les Cases de Alcanar, ca. 5 km south of Alfacs Bay (Fig - 1). -~~ - Three-dimensional current velocities were measured with an upward-looking Acoustic Doppler Current Profiler (ADCP, 2MHz Aquadopp, Nortek) moored at roughly 2 m depth since the maximum depth at this station was 3.5 m. - ~~It was configured to record 10-min average data with vertical cells of about 25 cm.~~ -

- ~~Water temperature and salinity were measured with the CTD48M (Sea&Sun Technology, Germany).~~ - ~~Unfortunately, a failure in the instrument caused the loss of the data corresponding to the temporal analysis at the fixed sampling station.~~ - ~~Temperature data provided by the multiple-parameter system LISST (Sequoia Scientific Inc.) were used instead.~~ -

- ~~Optical measurements.~~ - ~~Spectral beam attenuation coefficient was measured with the 25-cm path length VIPER (TriOS GmbH., Germany - [19]). -~~ - It is an open-path hyperspectral transmissometer which measures the beam attenuation, c(λ), in the spectral range from 360 nm to 750 nm, with an optical resolution of 15 nm (defined by the FWHM) and an acceptance angle of 0.8˚. - ~~More detailed information about the instrument performance and validation can be found in Ramı ´rez-Pe ´rez et al. (2015) - [34]. -~~ - ~~VIPER measurements were carefully performed (i.e. on the shadow side of the ship and under calm sea surface conditions) to avoid ambient light contamination - [34]. -~~ - ~~c(λ) data were collected continuously and averaged over 5 minutes.~~ - Milli-Q water references were subtracted and data were corrected for temperature and salinity dependence of pure seawater to derive the total non-water beam attenuation spectrum, c pg (λ) - [34]. - - ~~Measurements of particle size distribution (PSD) from 1.25 μm to 250 μm were conducted with the LISST-100X (Sequoia Scientific, Inc.).~~ - ~~This instrument measures the near-forward scattering at 32 logarithmically spaced angles and the beam attenuation at 670 nm - [35]. -~~ - ~~A successfully performance analysis between the attenuation measured at 670 nm by LISST and VIPER was previously carried out - [34]. -~~ - ~~Therefore, this study focused only on the LISST scattering data to derive the particle size distribution.~~ - ~~The volume concentration, V(D), was obtained through inversion of the angular forward scattering pattern using the manufacturerprovided inversion routine.~~ - ~~The used inversion algorithm is based on a kernel matrix derived from Mie theory of scattering by spherical particles.~~ - ~~Data from the outer and inner rings were excluded from further analysis due to the instability observed in the smallest and largest size ranges - [36]. -~~ - ~~Then, the particle number distribution, N(D), was calculated from the equation:~~ -

- NðDÞ ¼ 6 Á VðDÞ=ðpD 3 Þ - ð1Þ - -

- ~~where D represents the diameter of a volume-equivalent sphere for the midpoint of each size class.~~ - ~~To obtain the PSD, the average number of particles in each size class was divided by the width of the class, which is denoted as N'(D).~~ - ~~Finally, the PSD was fitted to the power-law function (or Junge distribution) - [37]: -~~ -

- N 0 ðDÞ ¼ N 0 ðD 0 Þð D D 0 Þ Àx - ð2Þ - -

- ~~where D 0 is a reference diameter, N'(D 0 ) the differential number concentration at D 0 and ξ is the nondimensional PSD slope.~~ - ~~Laboratory analysis of water samples.~~ -

- ~~• CDOM absorption measurements: absorbance spectra (240-600 nm) were acquired with the Aqualog fluorescence spectrometer (HORIBA JobinYvon, Germany) directly after sampling.~~ - ~~Water samples were syringe-filtered with 0.2 μm Whatman Spartan filters before analysis with 1 cm quartz cuvettes.~~ - ~~Absorbance measurements were further converted to absorption coefficient, which is used as a proxy for the CDOM content in a given water sample.~~ - ~~The Napierian absorption coefficient of CDOM at each wavelength (a λ ) was obtained from the given equation:~~ -

- a l ðm À1 Þ ¼ ð2:303 Á A l Þ=L - ð3Þ - -

- ~~where A λ is the absorbance at specific wavelength and L is the cuvette path length in meters.~~ -

- ~~More detailed information about the measurement protocol can be found in Gonc ¸alves-Araujo et al. (2015) - [38]. -~~ - ~~CDOM absorption spectra, a(λ), were fitted to the following exponential function - [39]: -~~ -

- aðlÞ ¼ aðl 0 Þ Á e ÀSðlÀl 0 Þ - ð4Þ - -

- ~~where S represents the spectral slope and a(λ 0 ), the absorption coefficient at a reference wavelength λ 0 (443 nm in this case).~~ - ~~The function was fitted to the wavelength range from 300 to 600 nm and extrapolated to 720 nm for later analysis of CDOM contribution at longer wavelengths.~~ -

- • Algal and non-algal particulate absorption (a ph (λ) and a nap (λ)): water samples were immediately filtered through ø 47-mm GF/F filters (pore size 0.7 μm), shock-frozen in liquid nitrogen and stored at -80˚C until analysis in the laboratory at the Alfred-Wegener-Institute. - The partition of the particulate absorption, a p (λ), into phytoplankton, a ph (λ), and non-algal absorption, a nap (λ), was performed by the filter pad technique following Ferrari and Tassan (1999) - [40]. - - ~~We used a Cary 4000 UV/VIS dual beam spectrophotometer equipped with a 150-mm integrating sphere (Varian Inc., USA) as described in Taylor et al. (2011) - [41]. -~~ - ~~The measurement procedures and data analysis were performed as detailed in Ro ¨ttgers and Gehnke (2012) - [42]. -~~ - ~~Phytoplankton absorption a ph was obtained as the difference between a p and a nap .~~ -

- ~~• Chlorophyll a: water samples for phytoplankton pigments analysis were filtered immediately after collection through ø 25-mm Whatman GF/F filters (pore size 0.7 μm).~~ - ~~Then, filters were shock-frozen in liquid nitrogen and stored at -80˚C until analysis in the laboratory at the Alfred-Wegener-Institute.~~ - ~~The extracted pigments were analyzed using the High Performance Liquid Chromatography (HPLC) technique following the method of Barlow et al.~~ -

- ~~(1997) - [43], with modification customized to our instruments as detailed in Taylor et al. -~~ -

- ~~(2011) - [41]. -~~ - ~~In this study, we use the Chl-a concentration as an index of phytoplankton biomass and covarying materials (biogenic detritus).~~ -

- • Total suspended matter concentration: TSM concentration was determined gravimetrically following Ro ¨ttgers et al. (2014) - [44] to reject potential errors associated with salt retention in the filters and loss of materials during washing and combustion - [44] - [45]. - - ~~Thereby, four different volumes of each water sample (within the range from 0.6 to 2.2 liters) were filtered immediately after collection through pre-weighed Whatman GF/F filters (ø 47 mm).~~ - ~~Afterwards, the gained mass of each filter was determined by subtracting the weight of the filter from the final weight.~~ - ~~A linear regression analysis was performed for filtered volume versus the gained mass, and the regression slope was taken as the TSM concentration value - [44]. -~~ -

- Data and statistical analysis -

- ~~This study explored the information contained in the beam attenuation spectrum as a proxy for different biogeochemical properties.~~ - ~~In particular, the analysis focused on three major spectral features, which are described as follow (Fig - 2): -~~ -

- ~~• Spectral slope: it is the major spectral shape feature of the beam attenuation coefficient and is related to the particle size distribution and CDOM content - [46]. -~~ - ~~For this reason and due to the lack of in situ CDOM absorption measurements, we used the total non-water beam attenuation spectral slope to detect variations in CDOM.~~ - ~~This simplification was adopted because of the high CDOM content in Alfacs Bay - [31] and the availability of additional particle size distribution measurements. -~~ - ~~To compute this parameter, beam attenuation spectra were fitted to the power-law function - [46]: -~~ -

- c pg ðlÞ ¼ c pg ðl r Þ Á ðl=l r Þ Àg - ð5Þ - -

- ~~where λ r is a reference wavelength (532 nm, in our case) and γ is the power-law slope.~~ - ~~The exponent was derived by non-linear least-squares regression, with a r 2 >0.98 in all cases.~~ -

- • Peak height associated with red band phytoplankton absorption peak: although c(λ) is typically a smoothly varying function of wavelength - [46] - [47], deviations from its theoretical behavior -associated with absorbing particles-have been reported by several authors - [48] - [49] - [50]. - - - Zaneveld and Kitchen (1995) - [48] observed step increases at the long-wavelength side of the chlorophyll absorption peaks as result of anomalous diffraction and dispersion - [51], which was called "absorption peak effects". - - ~~This local maximum is therefore expected to be related to the Chl-a content (in addition to other factors such as the particle size distribution) - [48]. -~~ - For this reason, the link between the local maximum of c(λ) and the Chl-a concentration was tested in this study, since it can provide a first estimate of phytoplankton biomass and covarying materials. - Similarly to Davis et al. (1997) - [52], who estimated the Chl-a concentration based on the red band absorption peak -a(676)-by subtracting a baseline, we computed the peak height in the red band of the beam attenuation spectrum. - - ~~However, here the local maximum was found at 685 nm (approximately 10 nm past the absorption peak, in agreement with Zaneveld and Kitchen (1995) - [48]). -~~ - ~~The attenuation at 710 nm was then subtracted from this local peak as a base value to remove the effect of particle scattering.~~ - ~~This wavelength was empirically chosen based on providing the best results (based on r 2 and RMSE as compared to collocated Chl-a data determined by HPLC at discrete samples).~~ - ~~Thereby, the peak height was computed as c pg (685)-c pg (710), which was used as a proxy for Chl-a concentration.~~ -

- • c pg (710): At long visible wavelengths, the attenuation is assumed to be determined mostly by their scattering properties and secondarily by the particulate absorption, whereas CDOM absorption has a insignificant contribution - [15, - [53] - [54] - [55]. - - ~~For this reason, the attenuation in the red part of the visible spectrum (i.e.~~ - 660 and 670 nm) has been commonly used as proxy for suspended particle concentration, since it responds primarily to concentration and secondarily to size and nature of the particles - [56]. - - While this assumption can be considered true in open waters, it could fail for complex coastal waters with high CDOM contents, which can yield a non-negligible CDOM absorption at long wavelengths (~700 nm) (e.g. - ~~- [57]). -~~ - ~~Nevertheless, the exponential decrease of CDOM absorption with wavelength involves that the longer the wavelength, the smaller its contribution to the beam attenuation signal.~~ -

- ~~For this reason, this study used the beam attenuation in the NIR (concretely at 710 nm) as proxy for TSM, where the CDOM absorption influence was minimum.~~ -

- ~~Variations in time and space of these optical parameters were analyzed by means of statistical techniques.~~ - In particular, the Kruskal-Wallis H-test was applied at 5% significance level (α = 0.05) in order to identify temporal and spatial patterns in Alfacs Bay, given that data were not normally distributed, as demonstrated by the Shapiro-Wilk test performed prior to analysis. - ~~On the other hand, since both inputs were subject to errors, a model II linear regression analysis was applied to investigate the relationships between optical parameters and biogeochemical variables.~~ - Additionally, the correlations between them were examined using nonparametric Spearman-r correlation coefficients and the associated errors were determined by means of the root mean squared error (RMSE). -

- Results and Discussion -

- ~~At first, the results from validating the above-mentioned beam attenuation-based proxies with laboratory-measured biogeochemical variables are presented.~~ - ~~Secondly, the temporal and spatial variability and patterns of these optical and biogeochemical parameters in Alfacs Bay are shown.~~ -

- Validation of biogeochemical proxies -

- ~~Attenuation at 710 nm vs. total suspended matter concentration.~~ - The comparison between the total non-water beam attenuation coefficient and the particulate and CDOM absorption at 710 nm (c pg (710), a p (710) and a CDOM (710), respectively) was performed to determine the relative contribution of the two last components to the bulk c pg (710) signal (Fig - 3a). - - ~~In all samples, a p (710) and a CDOM (710) represented a minor fraction of c pg (710), since their values were two orders of magnitude lower than c pg (710).~~ - ~~c pg (710) oscillated from 0.96 to 4.66 m -1 , whereas a p (710) and a CDOM (710) ranged from 0.0065 to 0.025 m -1 in our dataset.~~ - ~~The insignificant CDOM contribution to the attenuation signal at 710 nm, enabled to use c pg (710) as proxy for TSM.~~ - ~~Then, a model II linear regression analysis was applied to investigate the relationship between c pg (710) and TSM (Fig - 3b). -~~ - ~~The regression slope (± SD) was 0.224±0.03~~ - ~~gÁm -2 , which agreed with previous works - [53, - 54]. -~~ - In addition, although our slope was flatter, our observations were within the confidence bounds of the relationship found by - Neukermans et al. (2012) - [55] for the C-Star attenuation meter (with an acceptance angle of 1.2˚) (Fig - 3b). - - This disparity in the regression slope can be partly explained due to the different attenuation wavelength used in the relationship (670 and 710 nm in Neukermans et al. (2012) - [55] and in our study, respectively). - - ~~A significant correlation was observed between c pg (710) and TSM, with r 2 = 0.75 and RMSE = 0.49 m -1 (p<0.001).~~ -

- ~~c pg (685) peak height vs. Chl-a concentration.~~ - A relatively good linear correlation was found between the Chl-a concentration and the non-water attenuation peak height at 685 nm, c pg (685) peak (r 2 = 0.79, RMSE = 0.014 m -1 , p<0.001, Fig - 4a). - - ~~Thereby, it is reasonable to consider c pg (685) peak as a proxy for tracking changes in Chl-a concentration.~~ - Since this peak was associated with the red-band Chl-a absorption peak due to anomalous dispersion, the linear correlation between c pg (685) peak and the laboratory-derived phytoplankton absorption at 676 nm, a ph (676), was examined (Fig - 4b). - - ~~A significant linear correlation was also obtained in this case, with r 2 = 0.68 and RMSE = 0.014 m -1 (p<0.01).~~ - In turn, the correlation between Chla concentration and a ph (676) was analyzed (r 2 = 0.83; RMSE = 0.019 m -1 ; p<0.001) and compared to the power-law fit obtained by - Bricaud et al. (1995) - [58]. - - ~~Our observations were in agreement with the function predicted by those authors (Fig - 4c). -~~ - According to - Bricaud et al. (1995) - [58], the relationship between a ph (λ) and Chl-a varied as a result of changes in packaging effect and pigment composition. - - Our proxy is therefore suspected to be affected not only by these factors but also by minor contributions associated with CDOM and non-algal particles absorption, particle size distribution or Chl-a fluorescence, which compromise the relationship found between Chl-a concentration and c pg (685) peak height. - For this reason, we recommend this approach as a qualitative proxy, since its capability to provide quantitative estimates of Chl-a concentration should be further explored with a more extensive dataset. - ~~The potential influence of Chl-a fluorescence, which could lead to a decrease in the attenuation signal around 685 nm, was not evaluated here.~~ - Nevertheless, we assumed a minor effect since Chl-a fluorescence from the light beam leads to an emission into all directions, and therefore the amount of fluorescence into the direction of the beam towards the detector can be considered insignificant. -

- ~~Spectral slope of total non-water beam attenuation vs. a CDOM (443).~~ - The evolution of the attenuation spectral slope, the particle size distribution slope and the CDOM absorption at 443 nm was analyzed to evaluate the suitability of using c pg slope as an indicator of CDOM content. - ~~Variations in c pg slope responded mainly to changes in a CDOM (443), since both parameters exhibited a fairly similar behavior although the magnitude of these variations differed.~~ - ~~PSD slope, however, varied within a relatively narrow range (from 3.43 to 4.24), playing a smaller role in the variations observed in c pg slope (Fig - 5a). -~~ - Note that the PSD slope of the LISST and the VIPER-derived c pg slope are sensitive to different particle range given the distinct scattering angles they collect, which can contribute to the different behavior observed among both variables. - In order to test whether these variations in c pg slope were associated with changes in the magnitude of a CDOM instead of in the CDOM absorption spectral slope, S CDOM , the correlation between a CDOM (443) and S CDOM was analyzed (p<0.001). - An inverse relationship was found between both variables, which is consistent with the observations from - Helms et al. (2008) - [59] (Fig - 5b). - - ~~In contrast, no correlation was observed between S CDOM and c pg slope (p>0.1).~~ - ~~Finally, the relationship between a CDOM (443) and c pg slope showed a significant correlation (p<0.001),~~ - ~~although the coefficient of determination was not too strong (r 2 = 0.5; RMSE = 0.93).~~ - ~~This correlation was due to the high CDOM content in Alfacs Bay - [31]. -~~ - ~~For future studies, however, it is recommended to perform in situ measurements of 0.2 μm-filtered and unfiltered seawater alternatively to determine CDOM absorption separately (e.g.~~ - ~~- [14]). -~~ -

- Spatial variability -

- The horizontal and vertical spatial variability of the environmental, optical and biogeochemical parameters was analyzed based on vertical profiles measured at seven stations spread in Alfacs Bay (Fig - 6a). - - The vertical profiles of temperature and salinity showed a stratified water column, with a fresher and warmer surface layer and an underlying cooler and saltier water layer (Fig 6b - and 6c). - - ~~The pycnocline was located at ~3.5m depth, consistent with previous studies - [22, - [32] - [33]. -~~ - ~~The averaged temperature and salinity gradients between surface and bottom were of ΔT = 1.33˚C and ΔS = 1.84, with maximal differences of 2.1˚C and 2.7, respectively (found in the bay mouth).~~ -

- ~~The stratification of the water column determined the spatial variations observed in the optical properties.~~ - ~~Thereby, significant differences in the beam attenuation spectra as well as in CDOM and phytoplankton absorption spectra were found between surface and bottom water layers (i.e.~~ - ~~z 3.5 m and >3.5 m, respectively) (p<0.01)~~ - ~~(Fig - 7). -~~ - ~~Meanwhile, no noticeable differences were detected in the non-algal particulate absorption, a nap (λ) (not shown).~~ - ~~Waters below the pycnocline were characterized by a higher attenuation and phytoplankton absorption, whereas CDOM absorption was lower.~~ - ~~The shape of the particle size distribution was relatively homogeneous, although the PSD slope decreased slightly with depth (Table - 1) (p>0.05). -~~ -

- The analysis of the spatial patterns based on c pg (λ) measurements was carried out by using the above-mentioned attenuation spectral features -c pg (710), c pg (685) peak and c pg slope-and their relationships with the underlying biogeochemistry. - ~~In general, surface waters presented steeper c pg slopes and lower values of both c pg (685) peak and c pg (710).~~ - ~~In contrast, c pg (λ) measured below the pycnocline showed the opposite behavior, although their oscillations were larger (Table - 1, - Fig 8). -~~ - Statistically significant differences (p<0.01) between surface and bottom layers were found in c pg (710) and c pg slope, which increased by 40% and decreased by 27% with depth, respectively (Table - 1, Fig - 9a). - - ~~The observed decrease in the attenuation spectral slope with depth can be associated not only with a reduction in CDOM contribution but also with resuspension events.~~ - Horizontally, except slight differences detected in the bottom layer, no significant spatial patterns were observed along the different bay regions, suggesting a horizontal homogeneity in c pg (λ) spectral features (Fig - 8). - -

- On the other hand, the spatial variability observed in the biogeochemical parameters over the sampled transects were in agreement with the total non-water beam attenuation proxies, since noticeable differences were found between surface and bottom water layers for these as well. - ~~While TSM and Chl-a increased with depth, CDOM absorption decreased (Table - 1, Fig - 8). -~~ - ~~However, horizontal variations observed in the attenuation proxies were less pronounced than those in the biogeochemical variables (Fig - 8). -~~ -

- Finally, the results from the laboratory-measured absorption spectra exhibited differences in optical constituents contribution between surface and bottom layers, although the averaged magnitude of the total absorption was very similar for both cases (0.82 and 0.84 m -1 , respectively) (Fig - 9a). - - ~~The spatial variations found in these variables coincided with those observed from the beam attenuation-based analysis.~~ - The ternary plot of the partitioned absorption at each sampling station showed that surface waters were characterized by a higher proportion of CDOM and lower phytoplankton absorption than the water below the pycnocline, which presented larger particulate fraction (Fig - 9b). - - ~~These observations are consistent with a previous study in the region - [31], that found similar vertical distribution of optically active constituents (i.e. -~~ - ~~Chl-a, TSM, and CDOM).~~ -

- Temporal variability -

- ~~The 48 hours-time series of wind data showed a clear bimodal pattern with two dominant directions, from southwest and northwest (Fig - 10a and 10b). -~~ - ~~NW winds blew for ca.~~ - ~~10-12 hours during the nighttime (from 10 pm until 9:30 am, approximately) and shifted from SE to SW during daytime.~~ - ~~The velocities reached by southern winds were 5 mÁs -1 on average, with maximum values up to 8 mÁs -1 in the evening (8:30 pm).~~ - ~~The strongest winds blew from SW from 5 pm to 10 pm.~~ - The observed wind pattern responded to the typical land breeze characterized by weak nocturnal winds (<2 mÁs -1 ) blowing from land, that reverses the direction and increases the intensity during the daytime (sea breeze) - [30, - 33]. - - A similar behavior was observed in the surface current velocities, indicating that the water circulation at the sampling station was driven by the prevailing wind (Fig - 10c). - - ~~Thereby, surface water flowed in northward direction during daytime in response to southern winds and southwards when the wind ceased during nighttime.~~ - ~~This pattern was observed within the first 2 m depth, though the velocity decreased with depth.~~ -

- The effect of hydrodynamics on the water optical properties was analyzed for time and depth, and no significant correlations (p>0.05) between the optical properties and both the current velocity and direction were found. - ~~Thereby, the differences in the optical parameters between both prevailing flow regimes (i.e.~~ - ~~southward and northward currents) were not statistically significant (p>0.05)~~ - ~~(Fig - 11). -~~ -

- The surface current velocity (at 0.5 m depth) was 0.1 mÁs -1 on average, with a maximum value of 0. current velocity within the time interval from 6 pm to 12 am, on June 25, in agreement with c pg (710). - Nevertheless, the magnitude of this increase differed, since c pg (710) showed a rise of 20% with respect to the mean value, whereas a 40% increase was detected for TSM concentration (Fig - 13a). - - ~~Apart from this, no similar patterns were observed between both parameters along the time series, involving no significant correlation between TSM and c pg (710) (p>0.05).~~ - ~~In contrast, significant correlations were found between Chl-a concentration and c pg (685) peak (p<0.05), as well as between CDOM absorption at 443 nm and the attenuation spectral slope (p<0.01).~~ - ~~The bimodal pattern detected in the optical proxies was also observed within the bulk analyses of Chl-a and a CDOM (443).~~ - ~~Both variables increased their magnitude during southward current conditions (i.e. from 12 am to 12 pm, approximately) (Fig 13b - and 13c). -~~ -

- Conclusions -

- Continuous measurements of spectral beam attenuation coefficient collected in situ with an advanced-technology transmissometer have been proven as a powerful tool to better understand the existing interactions between physical and biogeochemical variables in the complex estuarine waters of Alfacs Bay (NW Mediterranean). - ~~In particular, this approach allowed the detection of qualitative changes in the major biogeochemical variables (i.e.~~ - ~~Chl-a, TSM and CDOM) at high temporal and spatial scales in this microtidal estuary.~~ - ~~Spatial patterns observed in the biogeochemical properties were driven by the vertical stratification of the water column.~~ - ~~Accordingly, surface and bottom water layers were characterized by a different relative contribution of the major biogeochemical variables to the bulk beam attenuation.~~ - Meanwhile, observations along the 48 hours time series revealed a coupling between physical (meteorological and hydrodynamic conditions) and biogeochemical properties, since the prevailing hydrodynamic regimes determined the variations in water composition. - ~~The temporal and spatial patterns were obtained based on the spectral features of the total non-water beam attenuation coefficient and validated with laboratory results of discrete water samples (i.e.~~ - ~~biogeochemical variables and partitioned absorption coefficients).~~ - ~~Significant linear relationships were found between the non-water beam attenuation proxies and the biogeochemical variables.~~ - ~~However, for future studies, it is highly recommended to include in situ beam attenuation measurements of 0.2 μm-filtered seawater for better CDOM characterization.~~ - The proposed proxies are subject to numerous uncertainties due to several factors affecting the attenuation signal (CDOM absorption and particle characteristics such as size, shape, composition, etc., which determine their absorption and scattering properties). - ~~For this reason, the collection of discrete water samples for laboratory analysis of biogeochemical variables is required for validation purposes.~~ -

- Our results based on a high-frequency, low power ( 3 W), compact, versatile (adaptable to different observing platforms) and cost-effective (~10000€) beam attenuation meter, as well as on a simple and rapid data processing method, have demonstrated a capability to improve the operational monitoring of coastal waters towards a better understanding of their complex physical and biogeochemical interactions. -

- Fig 1 . - 1 - -

- ~~Fig 1. Location map of Alfacs Bay in NW Mediterranean Sea.~~ - ~~The red star indicates the location of the weather station, whereas circles show the sampling stations for the analysis of temporal (blue circle) and spatial (red circles) patterns.~~ - ~~Map produced with Open Street Map.~~ - ~~doi:10.1371/journal.pone.0170706.g001~~ -

- - - -

- Fig 2 . - 2 - -

- ~~Fig 2. Representative total non-water beam attenuation spectrum measured in Alfacs Bay in June 2013.~~ - Numbers 1-3 indicate the three spectral features used in this study as proxies for biogeochemical variables: 1 = spectral slope of c pg (λ) for CDOM absorption, 2 = c pg (685)-c pg (710) for Chl-a and 3 = c pg (710) for TSM concentration. - ~~doi:10.1371/journal.pone.0170706.g002~~ -

- - - -

- Fig 3 . - 3 - -

- ~~Fig 3. (a) Comparison of c pg (710), a p (710) and a CDOM (710) along all the samples used in this study.~~ - ~~(b) Scatter plot of TSM and the attenuation at 710 nm.~~ - ~~Best fit ± 90% confidence intervals are shown in blue.~~ - ~~Black solid and dashed lines represent the 90% prediction bounds of the [TSM]-c p (670 nm) data of Neukermans et al. (2012) (for the C-Star).~~ - ~~doi:10.1371/journal.pone.0170706.g003~~ -

- - - -

- Fig 4 .Fig 5 .Fig 6 . - 456 - -

- ~~Fig 4. Scatter plots of (a) Chl-a concentration and c pg (685) peak.~~ - ~~(b) Phytoplankton absorption at 676 nm, a ph (676), and c pg (685) peak.~~ - ~~(c) Chl-a concentration and a ph (676).~~ - ~~The red line represents the power-law fit proposed by Bricaud et al. (1995).~~ - ~~Blue lines are the regression line ± 90% confidence intervals.~~ - ~~doi:10.1371/journal.pone.0170706.g004~~ -

- - - -

- ~~doi:10.1371/journal.pone.0170706.g006~~ -

- - -

- Fig 7 . - 7 - -

- ~~Fig 7. Optical properties measured at seven stations occupied in Alfacs Bay and over the water column.~~ - ~~(a) In situ measured total non-water beam attenuation spectra.~~ - ~~(b) LISST-derived size distribution for particle number.~~ - ~~(c) CDOM absorption and (d) phytoplankton absorption spectra.~~ - ~~Blue and red lines indicate measurements performed above and below the pycnocline, respectively.~~ - ~~doi:10.1371/journal.pone.0170706.g007~~ -

- - - -

- Table 1 . - 1 - -

- ~~Mean and standard deviation of the non-water beam attenuation-based proxies and biogeochemical variables for waters above and below the pycnocline (i.e.~~ - ~~z 3.5 m and z > 3~~ -

- - -

- Fig 8 . - 8 - -

- ~~Fig 8. Spatial distribution of proxies from non-water beam attenuation and biogeochemical variables.~~ - ~~Attenuation at 710 nm, c pg (710), vs. TSM at the (a) surface (z % 0.5 m) and (b) bottom (z % 5 m) layers of Alfacs Bay.~~ - ~~c pg (685) peak vs. Chl-a concentration at the (c) surface and (d) bottom layers.~~ - ~~c pg spectral slope vs. CDOM absorption at 443 nm at the (e) surface and (f) bottom layers.~~ - ~~Produced with Ocean Data View software [60].~~ - ~~doi:10.1371/journal.pone.0170706.g008~~ -

- - - -

- Fig 9 . - 9 - -

- ~~Fig 9. Analysis of partitioned absorption data.~~ - ~~(a) Contribution of the major biogeochemical variables to the total non-water absorption coefficient at 440 nm for the two different water layers.~~ - ~~(b) Ternary plot of the partitioned absorption coefficient at 440 nm (CDOM, phytoplankton, and non-algal particles) measured at the different sampling stations in Alfacs Bay.~~ - ~~Blue and red circles correspond to water samples collected above and below the pycnocline, respectively.~~ - ~~doi:10.1371/journal.pone.0170706.g009~~ -

- - - -

- ~~2 mÁs -1 , coinciding with SW winds episodes (Fig 12a).~~ - ~~In relation to the hydrographical variability, water temperature showed a marked diurnal cycle (day-night), with an oscillation of 1.2˚C.~~ - ~~It ranged from 23.2˚C (registered at 4 am) to 24.4˚C, at 6 pm (Fig 12b).~~ - While no significant correlations were found between physical and optical variables, the time series of c pg (710) and particle size distribution slope were characterized by an increase in their magnitude at periods of maximum current velocities, in response to the more intense northward currents (Fig 12-a, 12-c and 12-f). - ~~In contrast, c pg (685) peak and c pg spectral slope exhibited a bimodal pattern similar to that observed for the wind and current data.~~ - ~~Both parameters rose under weak southward current conditions, whereas the minimum values concurred with the maximum current velocities flowing northwards (Fig 12-a, 12-d and 12-e).~~ - ~~The temporal variations in biogeochemical properties showed similar patterns as those observed based on c pg proxies (Fig 13).~~ - ~~The concentration of particulate matter increased with~~ -

- - -

- Fig 10 . - 10 - -

- ~~Fig 10.~~ - ~~Time series of physical forcings along 48 hours.~~ - ~~(a) Wind speed and direction measured in the weather station located in Alcanar.~~ - ~~(b) Wind speed and direction (to) represented by arrows.~~ - ~~Upward pointing arrow indicates the North.~~ - ~~(c) Surface current velocity and direction represented by arrows, measured at 0.5 m depth with the ADCP located in the sampling station.~~ - ~~doi:10.1371/journal.pone.0170706.g010~~ -

- - - -

- Fig 11 . - 11 - -

- ~~Fig 11.~~ - ~~Optical measurements collected during profiling along 48 hours for the analysis of temporal patterns in Alfacs Bay.~~ - ~~(a) In situ measured total non-water beam attenuation spectra.~~ - ~~(b) LISST-derived size distribution for particle number.~~ - ~~(c) CDOM absorption and (d) phytoplankton absorption spectra.~~ - ~~Blue and red lines indicate measurements performed under the influence of southward and northward currents, respectively.~~ - ~~doi:10.1371/journal.pone.0170706.g011~~ -

- - - -

- Fig 12 . - 12 - -

- ~~Fig 12. Variations with time and depth in the attenuation-based proxies and PSD slope along with the current velocity.~~ - ~~(a) Temporal dataset of current velocity measured within the first 2 m depth.~~ - ~~Time series of vertical profiles of (b) water temperature, (c) c pg (710), (d) c pg (685) peak, (e) c pg spectral slope and (e) LISST-derived PSD slope.~~ - ~~doi:10.1371/journal.pone.0170706.g012~~ -

- - - -

- -

- - - - PLOS ONE | DOI:10.1371/journal.pone.0170706 January 20, 2017 - - - -

- Acknowledgments -

- ~~We thank E. Zafra for his dedication and effort in organizing, planning and performing the field campaign.~~ - ~~We also thank to J. Ballabrera, A. Olariaga and V. Fuentes (ICM-CSIC, Spain), for their support and collaboration during the field campaign.~~ - ~~We are grateful to E. Boss and an anonymous reviewer for providing valuable comments on the manuscript.~~ -

- Author Contributions -

- ~~Conceptualization: MR-P RR AB JP.~~ -

- Formal analysis: MR-P RG-A. -

- Funding acquisition: ET AB JP. -

- ~~Investigation: MR-P RG-A SW RB AB JP.~~ -

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