added sections on survival analysis and other associated changes.

temporaryWork
Will King 5 years ago
parent 01426f1080
commit 75513bfb81

Binary file not shown.

@ -19,23 +19,46 @@
\newpage
\section{Introduction}
\subfile{sections/00_Introduction}
\subfile{sections/00_Introduction} %TODO
\section{Laws of Motion}
\subfile{sections/01_LawsOfMotion}
\subfile{sections/01_LawsOfMotion} %DONE
\section{Kessler Syndrome}\label{SEC:Kessler}
\subfile{sections/02_KesslerSyndrome}
\section{Survival Analysis}\label{SEC:Survival}
\subfile{sections/03_SurvivalAnalysis}
\section{Motion Results}\label{SEC:MotionResults}
The following are two results due to the laws of motion presented.
\section{Constellation Operator's Program}\label{SEC:Operator}
\subfile{sections/04_ConstellationOperator}
\subsection{Kessler Regions}
\subfile{sections/06_KesslerRegion} %TODO
\section{Social Planner's Program}\label{SEC:Planner}
\subfile{sections/05_SocialPlanner}
\subsection{Survival Analysis}\label{SEC:Survival}
\subfile{sections/03_SurvivalAnalysis} %TODO
\section{Model}
\subsection{Constellation Operator's Program}\label{SEC:Operator}
\subfile{sections/04_ConstellationOperator} %TODO
\subsection{Social Planner's Program}\label{SEC:Planner}
\subfile{sections/05_SocialPlanner} %TODO
\section{Computation}
No work has been done here so far.
\section{Assumptions and Caveats}
I hope to write a section clearly explaining assumptions, caveats, and shortcomings here.
%time periods are long enough for debris to disperse after collisions.
%Only a single type of debris
%With my current computational idea; each constellation provides the same risk to each other constellation
% That can be easily adjusted in the computational models.
\section{Appedicies}
\subsection{Mathematical Notation}
Needs completed.
\subsection{Derivations}
\subsubsection{Marginal Survival Rates}\label{APX:Derivations:SurvivalRates}
\subfile{sections/appedicies/apx_01_MarginalSurvivalRates}
\end{document}

@ -63,7 +63,9 @@ These effects can be represented by the following general law of motion.
\end{align}
I formulate this more specifically as:
\begin{align}
D_{t+1} = (1-\delta)D_t + g(D_t) + \sum^N_{i=1} \gamma l^i(\{s^j_t\},D_t) + \Gamma x^i_t
D_{t+1} = (1-\delta)D_t + g(D_t)
+ \sum^N_{i=1} \gamma l^i(\{s^j_t\},D_t)
+ \Gamma \sum^n_{j=1} \{x^j_t\}
\end{align}
where $\Gamma,\gamma$ represent the debris generated by each launch and collision respectively,
while $\delta,g(\cdot)$ represent the decay rate of debris and the

@ -67,6 +67,7 @@ would not.
I believe, but have not verified, that some choices of $\epsilon$, although permitting cycles,
would relegate them to levels with minimal economic impact.
%Maybe can be studies by phase or flow diagrams?
%Consider where it cycles between just below epsilon and then to a large increase in debris?
%Area of research: What makes a good \epsilon?

@ -2,7 +2,60 @@
\graphicspath{{\subfix{Assets/img/}}}
\begin{document}
Introduction goes here
\subsection{testing}
This is a subsection of the introduction.
In his dissertation \cite{RaoDissertation} briefly examines the "survival rates" of a satellite constellation.
I've applied this to my model and extended the results.
% Marginal survival.
The survival rate for a constellation $i$ is defined as $R_i = 1-l^i(\cdot)$, the proportion of satellites-
that were not lost (degraded nor destroyed) between period $t$ and $t+1$.
Thus the marginal survival rate represents the additional loss of
satellites due to a slightly larger constellation or fleet stock.
Let $S_t = \sum^n_{j=1} s^j_t$.
Then the survival rates for a constellation and for society's fleet are respectively defined as:
\begin{align}
R_i =& \frac{s^i_{t+1}- x^i_t}{s^i_t} = 1- l^i(s^i_t,S_t,D_t) \\
R =& \frac{S_{t+1}- X_t}{S_t} = \frac{\sum_{i=1}^N s^i_t[1-l^i(s^i_t,S_t,D_t)] }{S_t} \label{EQ:socsurv}
\end{align}
In this case, the fleet survival rate \cref{EQ:socsurv}, represents the proportion of satellites-
in period $t+1$ that survived from period $t$.
The marginal survival rates when a given constellation $i$ changes size are:
\begin{align}
\parder{R_i}{s^i_t}{} =& -\left(\parder{l^i}{s^i_t}{} + \parder{l^i}{S_t}{}\parder{S_t}{s^i_t}{} \right)
= - \parder{l^i}{s^i_t}{} - \parder{l^i}{S_t}{} \label{EQ:iii} \\
\parder{R}{s^i_t}{} =& \frac{S_t \sum_{i=1}^N \left( [1-l^i(s^i_t,S_t,D_t)]
+ s^i_t [ -\parder{l^i}{s^i_t}{} -\parder{l^i}{S_t}{}\parder{S_t}{s^i_t}{}] \right)
- \left( \sum_{i=1}^N s^i_t[1-l^i(s^i_t,S_t,D_t)] \right)}
{(S_t)^2} \notag{}\\
=& \sum_{i=1}^N \left[ \frac{R_i}{S_t} \right] - \frac{R}{S_t}
+\sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{} \label{EQ:i}
\end{align}
Note that $ \sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{}$ is the weighted, average marginal survival rate-
across constellation operators.
The derivation of \cref{EQ:i} is in Appendix \ref{APX:Derivations:SurvivalRates}.
Direct comparison between the marginal survival rates of an individual operator and the social planner's fleet
cannot proceed further without specifying the functional loss forms $l^i(\cdot)$
and specifying which firm will be compared to society.
In spite of this, conditions on the average effects can be developted as follows.
The marginal survival rate of the fleet is less than the weighted, arithmetic mean of marginal survival rates-
of the constellations when:
\begin{align}
\sum_{i=1}^N \left[ \frac{R_i}{S_t} \right] - \frac{R}{S_t}
+\sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{}
\leq& \sum_{i=1}^N \frac{s^i_t}{S_t} \parder{R_i}{s^i_t}{} \\
\sum_{i=1}^N R_i - R \leq& 0\\
\sum_{i=1}^N [1- l^i(s^i_t,S_t,D_t)] - \sum_{i=1}^N s^i_t [1- l^i(s^i_t,S_t,D_t)] \leq& 0\\
\sum_{i=1}^N (1 - s^i_t) [1- l^i(s^i_t,S_t,D_t)] \leq& 0 \label{EQ:ii}
\end{align}
which is true if every constellation has at least one satellite.
As any constellation of interest has at least one satellite
and $\parder{R_i}{s^i_t}{} < 0$ from the assumption on collision mechanics that $\der{l^i}{s_t^i}{}>0$,
we conclude that the marginal survival rate of the entire satellite fleet is lower
than the weighted arithmetic mean of marginal survival rates across constellations.
Note that it is possible for some constellations to have a lower marginal survival rate than the fleet,
but the survival rate for many operators must be higher than the societal rate.
Consequently, we would expect many operators to underestimate the impact of their behaviors on others
if they use their own observed or expected risk factors to estimate the risk they impose on others.
\end{document}

@ -0,0 +1,24 @@
\documentclass[../Main.tex]{subfiles}
\graphicspath{{\subfix{Assets/img/}}}
\begin{document}
Derivations related to the marginal survival rate analysis.
\begin{align*}
\parder{R_i}{s^i_t}{} =& -\left(\parder{l^i}{s^i_t}{} + \parder{l^i}{S_t}{}\parder{S_t}{s^i_t}{} \right)
= - \parder{l^i}{s^i_t}{} - \parder{l^i}{S_t}{} \\
\parder{R}{s^i_t}{} =& \frac{S_t \sum_{i=1}^N
\left( [1-l^i(s^i_t,S_t,D_t)] + s^i_t [ -\parder{l^i}{s^i_t}{} -\parder{l^i}{S_t}{}\parder{S_t}{s^i_t}{}] \right)
- \left( \sum_{i=1}^N s^i_t[1-l^i(s^i_t,S_t,D_t)] \right)}{(S_t)^2} \\
=& \sum_{i=1}^N \left[ \frac{S_t [1-l^i(s^i_t,S_t,D_t)]}{(S_t)^2}
- \frac{ s^i_t[1-l^i(s^i_t,S_t,D_t)] }{(S_t)^2} \right]
+\sum_{i=1}^N \frac{ s^i_t S_t [ -\parder{l^i}{s^i_t}{} - \parder{l^i}{S_t}{}] }{(S_t)^2} \\
=& \sum_{i=1}^N \left[ \frac{S_t - s^i_t}{(S_t)^2}[1-l^i(s^i_t,S_t,D_t)] \right]
+\sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{} \\
=& \sum_{i=1}^N \left[ \frac{1}{S_t}[1-l^i(s^i_t,S_t,D_t)] \right] - \frac{R}{S_t}
+\sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{} \\
=& \sum_{i=1}^N \left[ \frac{R_i}{S_t} \right] - \frac{R}{S_t}
+\sum_{i=1}^N \frac{ s^i_t}{ S_t} \parder{R_i}{s^i_t}{}
\end{align*}
\end{document}
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