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+
+time to heat up domestic water: pasta pot, hot tub, etc
+
+function of starting temperature, environmental temperature, insulation, volume/surface area
+
+## Paper read: "The impact of mathematical modeling languages on model quality in systems biology"
+
+    The impact of mathematical modeling languages on model quality in systems biology: A software engineering perspective
+    Christopher Sch¨olzel1, Valeria Blesius, Gernot Ernst, and Andreas Dominik
+    https://www.biorxiv.org/content/10.1101/2019.12.16.875260v3
+
+Interesting refs:
+
+- [A long journey into reproducible computational neuroscience](https://www.frontiersin.org/articles/10.3389/fncom.2015.00030/full)
+- Guidelines for Reproducibly Building and Simulating Systems Biology Models
+-  Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement
+- Antimony: A Modular Model Definition Language
+- SimuPy: A Python Framework for Modeling and Simulating Dynamical Systems
+- Systems Modeling and Programming in a Unified Environment Based on Julia
+- Recent advances in biomedical simulations: a manifesto for model engineering
+
+> [...] Guyton model, which is probably among the most complicated monolithic models in systems biology [...]
+
+## Modia: Modelica-like in Julia
+
+Slides: https://modiasim.github.io/Modia.jl/slides/Systems-Modeling-and-Programming-Slides.pdf
+
+Code: https://github.com/ModiaSim/Modia.jl
+
+Expresses a strong interest in visual representation.
+
+
+## Lean / mathlib
+
+<https://leanprover-community.github.io/>
+
+<https://www.quantamagazine.org/building-the-mathematical-library-of-the-future-20201001/>
+
+
+## Other
+
+Had not heard of "SimScape", a component of MATLAB along side Simulink.
+
+There is a somewhat arbitrary list of "100 theorems" used to compare systems
+like Lean and Coq: <https://www.cs.ru.nl/~freek/100/>. What would a model or
+physical systems equivalent include?
+
+Interchange-like format for Modelica: <https://fmi-standard.org/>
+
+What features should next modelthing iteration have?
+
+- s-expr native syntax
+- modularity/hierarchy
+- "hybrid" (including discrete)
+- input: mathml
+- output: c, wasm, julia, modelica, mathml, latex, text
+- some datastore, with ability to fetch code from website/API
+
+What are the type systems and data model of computer algebra systems?
diff --git a/2020/10/2020-10-24.md b/2020/10/2020-10-24.md
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+
+## edn and s-expr syntax
+
+Got excited about edn ("extensible data notation"), which is sort of a
+formalization of extended s-expressions from closure world. Could try to stick
+to a subset of this syntax to get free parsing in several languages? Maybe just
+as a place to start.
+
+- https://github.com/edn-format/edn
+- https://crates.io/crates/edn-rs
+- https://hackage.haskell.org/package/hedn
+
+Other s-expr notes and references:
+
+- https://github.com/rotty/lexpr-rs/blob/master/lexpr/docs/why.md
+- r7rs-small syntax notes
+
+
+## racket symalg package
+
+<https://docs.racket-lang.org/symalg/index.html>
+
+Every simply/basic API. Can convert to/from "algebraic expression" objects,
+simple s-expr, infix, and latex. Has simplification, differentiation, and
+evaluation helpers.
+
+
+## Computer Algebra and Symbolic Computation books by Joel Cohen
+
+Fairly basic. Referenced from the racket symalg docs.
+
+
+## Web Math Editors
+
+Nice simple formula editors, implemented in Javascript. Eg, fractions,
+exponentials. integrals, greek symbols, etc.
+
+- <http://mathquill.com/>
+- <http://mathlive.io/examples/basic/index.esm.html>
diff --git a/2020/10/2020-10-26.md b/2020/10/2020-10-26.md
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+
+Reminded of asciimath, as well as jqmath.
diff --git a/2020/10/hot_tub_heating.md b/2020/10/hot_tub_heating.md
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+
+## Heating Water Pool Model
+
+For a pool of a given size (liters/gallons), with given insulation (R-value or
+U-value), at an external air temperature, with/without a cover, with a given
+input of electrical heating power, at a given initial temperature:
+
+- how long to heat to a given temperature
+- power needed to maintain temperature
+- how much energy to heat
+
+Assumptions/constraints:
+
+- atmospheric pressure
+- water stays between freezing and boiling
+- humidity?
+
+Overall refs:
+
+- [Energy Smart Pools Software](http://www.rlmartin.com/rspec/software.htm)
+
+### Units
+
+A BTU (Britich Thermal Unit) is the amount of heat (energy) which will increase
+the temperature of one pound of water by one degree Fahrenheit.
+
+A calorie (SI) is the amount of heat (energy) which will increase the
+temperature of one gram of water by one degree Celsius.
+
+1 BTU ~= 1055 Joule
+1 BTU ~= 0.2931 watt hours
+1 BTU ~= 252 calories
+
+Refs:
+
+- [Wikipedia: BTU](https://en.wikipedia.org/wiki/British_thermal_unit)
+
+### Heating
+
+heat capacity of water: 4200 Joules / Kelvin / gramm
+
+T: temperature
+P: power (Watt)
+t: time (second)
+C: heat capacity (Joules / Kelvin)
+m: mass (gramm)
+
+dT/dt = P / (C * m)
+
+### Conductive heat loss
+
+Conductive loss (walls, floor):
+
+theta: "heat flow rate" (Watt)
+A: surface area (meter^2)
+deltaT: temperature difference (Kelvin)
+R_val: R-value (Kelvin * meter^2 / Watt)
+
+assertion: T >= T_env
+
+deltaT = T - T_env
+theta = (deltaT * A) / R_val
+
+Refs:
+
+- [How To Calculate Heat Loss?](https://industrialheatingsystems.com/How-calculate-heat-loss.html)
+
+### Evaporative heat loss
+
+This part is trickier, lots of factors could be included.
+
+k_s: heat loss factor
+deltaT: temperature difference (Kelvin)
+A: surface area (meter^2)
+
+TODO
+
+- [Measurement and Analysis of Evaporation from an Inactive Outdoor Swimming Pool](http://www.rlmartin.com/rspec/whatis/studies_outdoor_inactive.htm)
+- [How to Calculate Water Evaporation Loss in a Swimming Pool](https://dengarden.com/swimming-pools/Determine-Evaporation-Rate-for-Swimming-Pool)
diff --git a/2020/10/other_models.md b/2020/10/other_models.md
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+
+## Wind Chill
+
+T_wc = 13.13 + 0.6 * T - (13.95 - 0.486 * T) * v^(0.16)
+
+T: temperature (Celsius)
+v: wind velocity at 10m height (meter/second)
diff --git a/2020/10/sexpr_syntax.md b/2020/10/sexpr_syntax.md
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+https://github.com/edn-format/edn