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Commit 7a988638 authored by Sam Yates's avatar Sam Yates
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More minor fixes to cable computation document.

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......@@ -52,7 +52,6 @@ is injected at the left end of the cable from $t=0$, and the initial potential
is the reversal potential.
\begin{table}[ht]
\label{tbl:rallpack1}
\centering
\begin{tabular}{lSl}
\toprule
......@@ -67,6 +66,7 @@ is the reversal potential.
\bottomrule
\end{tabular}
\caption{Cable properties for the Rallpack 1 model.}
\label{tbl:rallpack1}
\end{table}
The potential on a constant-radius passive cable is governed by the PDE
......@@ -132,7 +132,7 @@ From
The boundary conditions \eqref{eq:normcableleft} and \eqref{eq:normcableright} give
\begin{align}
\label{eq:lapleft}
\frac{\partial G}{\partial x}(0, s) & = \frac{1}{s},
\frac{\partial G}{\partial x}(0, s) & = \frac{1}{s}
\\
\label{eq:lapright}
\frac{\partial G}{\partial x}(L, s) & = 0.
......@@ -144,12 +144,13 @@ Solutions to \eqref{eq:lap} must be of the form
\end{equation}
where $m=\sqrt{1+s}$. From \eqref{eq:lapleft} and \eqref{eq:lapright},
\begin{align*}
mA(s) - mB(s) & = \frac{1}{s},
mA(s) - mB(s) & = \frac{1}{s}
\\
mA(s)e^{mL} -mB(s)e^{-mL} & = 0.
\end{align*} and thus
mA(s)e^{mL} -mB(s)e^{-mL} & = 0
\end{align*}
and thus
\begin{align*}
A(s) & = \frac{1}{sm (1-e^{2mL})},
A(s) & = \frac{1}{sm (1-e^{2mL})}
\\
B(s) & = \frac{e^{2mL}}{sm (1-e^{2mL})}.
\end{align*}
......@@ -166,7 +167,7 @@ Consequently,
Sufficient conditions for the inverse transform of $G(x,s)$ to exist
and be representable in series form are as follows
\parencite[][Theorem 4]{churchill1937}):
\parencite[][Theorem 4]{churchill1937}:
\begin{enumerate}
\item
$G(x, s)$ is analytic in some right half-plane $H$,
......@@ -213,7 +214,7 @@ $2k\pi\delta/L+\delta^2$ about $s_k$ for $k\geq 1$, which then are separated by
circles $|s|=\rho_k$ about the origin for some $\rho_k$ in $(|s_k|, |s_k+1|)$.
\textbf{Pole at $s=0$}.\\
Recalling $m=\sqrt{1+s}$, $m$ and $\sinh mL$ are non-zero in\\
Recalling $m=\sqrt{1+s}$, $m$ and $\sinh mL$ are non-zero in
a neighbourhood of $s=0$, and so the pole is simple and
\begin{equation}
\begin{aligned}
......@@ -257,7 +258,7 @@ Consequently the pole is simple and
\Res(G; s_k)
& = f(x, s_k)/h'(s_k)\\
& = -\frac{2}{s_k L}\frac{\cosh m_k(L-x)}{\cosh m_kL} \\
& = -\frac{2}{s_k L}\frac{\cosh m_kL\cosh m_kx-\sinh m_kL\sinh m_kL)}{\cosh m_kL} \\
& = -\frac{2}{s_k L}\frac{\cosh m_kL\cosh m_kx-\sinh m_kL\sinh m_kL}{\cosh m_kL} \\
& = -\frac{2}{s_k L}\cosh m_k x,
\end{aligned}
\end{equation}
......@@ -297,10 +298,10 @@ residual. The $a_k$ form an increasing sequence, so
\end{aligned}
\label{eq:gbar}
\end{equation}
Substituting $u=v/\sqrt{t}$ gives the identity
Substituting $u=\sqrt{v/t}$ gives the identity
\begin{equation}
\int_{a}^\infty \frac{e^{-tu^2}}{u^2}\,du
= \frac{1}{2}\sqrt{t}\int_{a^2t}^\infty e^{-v} v^{\frac{-3}{2}}\,dv
= \frac{1}{2}\sqrt{t}\int_{a^2t}^\infty e^{-tv} v^{\frac{-3}{2}}\,dv
= \frac{1}{2}\sqrt{t}\,\Gamma(-\frac{1}{2},a^2 t),
\end{equation}
where $\Gamma(\alpha, z)$ is the upper incomplete gamma function.
......
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