tring to finish the sigma delta analysis, keeps becoming 10pm too quickly
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@ -51,9 +51,9 @@ paper
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{
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{
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chapter
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chapter
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}
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}
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starts with a worked example of the new methodology Failure Mode Modular De-composition (FMMD), and then
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starts with a worked example using the new methodology, Failure Mode Modular De-composition (FMMD), and then
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describes the data types and concepts for the method, using these a UML class model is built
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develops an ontological structure for the methodology using UML class models.
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and then notation is developed.
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A notation is then described to index and classify objects created in FMMD models.
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@ -4,7 +4,8 @@ PNG_DIA = blockdiagramcircuit2.png bubba_oscillator_block_diagram.png circuit1
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dubsim1.png invamp.png mvampcircuit.png pd.png plddouble.png plddoublesymptom.png \
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dubsim1.png invamp.png mvampcircuit.png pd.png plddouble.png plddoublesymptom.png \
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poss1finalbubba.png poss2finalbubba.png pt100.png pt100_doublef.png pt100_singlef.png \
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poss1finalbubba.png poss2finalbubba.png pt100.png pt100_doublef.png pt100_singlef.png \
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pt100_tc.png pt100_tc_sp.png shared_component.png stat_single.png three_tree.png \
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pt100_tc.png pt100_tc_sp.png shared_component.png stat_single.png three_tree.png \
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tree_abstraction_levels.png vrange.png sigma_delta_block.png ftcontext.png ct1.png hd.png
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tree_abstraction_levels.png vrange.png sigma_delta_block.png ftcontext.png ct1.png hd.png \
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sigdel1.png
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@ -1706,7 +1706,7 @@ and fed into the summing integrator completing the negative feedback loop.
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The partslist for the $\Sigma \Delta $ADC
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The partslist for the $\Sigma \Delta $ADC
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$$\{ IC1, IC2, IC3 IC4 \} $$.
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$$\{ IC1, IC2, IC3, IC4, R1, R2, R3, R4, C1 \} $$.
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IC1,2 and 3 are all Op-amps and we have failure modes from section~\ref{sec:opampfm}.
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IC1,2 and 3 are all Op-amps and we have failure modes from section~\ref{sec:opampfm}.
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@ -1722,8 +1722,12 @@ The resistors and capacitor failure modes we take from EN298~\cite{en298}[An.A]
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$$ fm ( R ) = \{OPEN, SHORT\} $$
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$$ fm ( R ) = \{OPEN, SHORT\} $$
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$$ fm ( C) = \{OPEN, SHORT\} $$
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$$ fm ( C ) = \{OPEN, SHORT\} $$
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\subsection{Identifying initial {\fgs}}
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\subsubsection{Summing Junction}
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We now need to choose {\fgs}. The signal path is circular, but we can start
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We now need to choose {\fgs}. The signal path is circular, but we can start
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with the input voltage, which is applied to $R2$, we can term this voltage $V_{in}$.
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with the input voltage, which is applied to $R2$, we can term this voltage $V_{in}$.
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$R2$ and $R1$ form a summing junction to IC1.
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$R2$ and $R1$ form a summing junction to IC1.
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@ -1732,7 +1736,7 @@ This can be our first {\fg}. For the symptoms, we have to think in terms of the
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on its performance as a summing junction and not be
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on its performance as a summing junction and not be
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distracted by the integrator formed by $C_1$ and $IC1$.
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distracted by the integrator formed by $C_1$ and $IC1$.
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$$G^0_1 = \{R1, R2\}$$
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$$G^0_1 = \{R1, R2 \}$$
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\begin{table}[h+]
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\begin{table}[h+]
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\caption{R1,R2 Summing Junction: Failure Mode Effects Analysis} % title of Table
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\caption{R1,R2 Summing Junction: Failure Mode Effects Analysis} % title of Table
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@ -1757,15 +1761,21 @@ From the analysis in table~\ref{tbl:sumj}, we can now create a derived component
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$SUMJ$ which has the failure modes from collecting its symptoms.
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$SUMJ$ which has the failure modes from collecting its symptoms.
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We can state
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We can state
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$$ fm(SUMJ) = \{ V_{in} DOM, V_{in} DOM \} $$
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$$ fm(SUMJ) = \{ V_{in} DOM, V_{fb} DOM \} $$
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\subsubsection{Buffered Integrator}
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Following along the signal path, the next functional group is the integrator.
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Following the signal path, the next functional group is the integrator.
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This integrator is simply by $IC2$. This performs the function of
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This integrator is formed by $C$ by $IC2$\cite{aoe}[ch.4].
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isolating the integrator from any load on its output. We can therefore include this as well.
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The output of the integrator is fed into IC2, which acts as a buffer.
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%performing the function of
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isolating the integrator from any load on its output.
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These three components work together to form a buffered integrator,
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and nicely form a {\fg}.
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$$G^0_2 = \{IC1, C1, IC2\}$$
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$$G^0_2 = \{IC1, C1, IC2\}.$$
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The buffered integrator is analysed in table~\ref{tbl:intg}.
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\begin{table}[h+]
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\begin{table}[h+]
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@ -1796,10 +1806,111 @@ $$G^0_2 = \{IC1, C1, IC2\}$$
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From the analysis in table~\ref{tbl:intg}, we can now create a derived component
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From the analysis in table~\ref{tbl:intg}, we can now create a derived component
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$SUMJ$ which has the failure modes from collecting its symptoms.
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$BFINT$ which has the failure modes from collecting symptoms from the analysis in table~\ref{tbl:intg}.
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We can state
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We can state
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$$ fm (SUMJ) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$
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$$ fm (BFINT) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$
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\subsubsection{Digital level to analogue level conversion ($DL2AL$).}
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Digital level to analogue level conversion is performed by IC3 in conjunction with a potential divider formed by R3,R4.
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The potential divider provides a mid rail reference voltage
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to the inverting input of IC3.
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\paragraph{Potential divider Formed by R3,R4.}
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We re-use the analysis from section~\ref{sec:pd}, and used the derived component $PD$
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to represent the potential divider formed by R3 and R4. Because PD is a derived component, we can denote this
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by super-scripting it with its abstraction level of 1, thus $PD^1$.
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$$
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fm(PD^1) = \{ HIGH, LOW \}.
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$$
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IC3 is an op-amp and has the failure modes
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$$fm(IC3) = \{\{ HIGH, LOW, NOOP, LOW\_SLEW \} . $$
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The digital signal is supplied to the non-inverting input.
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The output is a voltage level in the analogue domain $-V$ or $+V$.
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We now form a {\fg} from $PD^1$ and $IC3$.
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$$ G^1 = \{ PD^1, IC3 \} $$
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We now analyse the {\fg} $G^1$ in table~\ref{tbl:DS2AS}.
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\begin{table}[h+]
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\caption{$PD^1, IC3$ Digital level to analogue level converter: Failure Mode Effects Analysis} % title of Table
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\label{tbl:DS2AS}
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\begin{tabular}{|| l | l | c | c | l ||} \hline
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\textbf{Failure Scenario} & & \textbf{failure result } & & \textbf{Symptom} \\
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& & & & \\
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\hline \hline
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FS1: $PD^1$ $HIGH$ & & output perm. low & & LOW \\
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FS2: $PD^1$ $LOW$ & & output perm. low & & HIGH \\ \hline
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\hline
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FS3: $IC3$ $HIGH$ & & output perm. high & & HIGH \\
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FS4: $IC3$ $LOW$ & & output perm. low & & LOW \\ \hline
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FS5: $IC3$ $NOOP$ & & no current drive & & LOW \\
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FS6: $IC3$ $LOW\_SLEW$ & & delayed signal & & LOW\_SLEW \\ \hline
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\hline
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\end{tabular}
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\end{table}
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We collect the symptoms of failure $\{ LOW, HIGH, LOW\_SLEW \}$.
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We can now derive a new component to represent the level conversion and call it $DL2AL$.
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$$ DL2AL = D(G^1) $$
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$$ fm (DL2AL) = \{ LOW, HIGH, LOW\_SLEW \} $$
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\subsubsection{digital clocked memory (flip-flop).}
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This is a single component as a {\fg}, and we can state
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$$ fm (DCM) = \{ HIGH, LOW, NOOP \} $$
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\subsection{First {\fgs} analysed}
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We have analysed the initial {\fgs} and can now take stock of the situation
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and see what is now required. Figure~\ref{fig:sigdel1} shows how far the
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hierarchy has been built.
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\begin{figure}[h+]
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\centering
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\includegraphics[width=400pt]{./CH5_Examples/sigdel1.png}
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% sigdel1.png: 766x618 pixel, 72dpi, 27.02x21.80 cm, bb=0 0 766 618
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\caption{First stage of FMMD analysis: Sigma delta Converter}
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\label{fig:sigdel1}
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\end{figure}
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IC4 is as yet unused, the signal path connects IC4 and DL2AL. These seem natural candidates
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for the next {\fg}.
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BFINT and SUMJ are adjacent in the signal path and these are chosen as a {\fg} as well.
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\subsubsection{{\fg} BFINT and SUMJ}
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\subsubsection{{\fg} IC4 and DL2AL}
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\subsection{Final, top level {\fg} for sigma delta Converter}
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% ]
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% ]
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% into
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% into
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%
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%
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@ -1819,40 +1930,41 @@ $$ fm (SUMJ) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$
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% and IC3.
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% and IC3.
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% The output from this is sent to the summing integrator as the signal summed with the input.
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% The output from this is sent to the summing integrator as the signal summed with the input.
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\subsection{Identifying initial {\fgs}}
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\subsubsection{Summing Junction formed by R1 and R2}
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The resistors R1, R2 form a summing junction
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to the negative input of IC1.
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Using the earlier definition for resistor failure modes,
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$fm(R)= \{OPEN, SHORT\}$, we analyse the summing junction
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in table~\ref{tbl:sumjunct} below.
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\begin{table}[h+]
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\caption{Summing Junction: Failure Mode Effects Analysis: Single Faults} % title of Table
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\label{tbl:sumjunct}
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\begin{tabular}{|| l | l | c | c | l ||} \hline
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\textbf{Failure Scenario} & & \textbf{Summing} & & \textbf{Symptom} \\
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& & \textbf{Junction} & & \\
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\hline
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FS1: R1 SHORT & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
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FS2: R1 OPEN & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
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FS3: R2 SHORT & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
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FS4: R2 OPEN & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
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\hline
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\end{tabular}
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\end{table}
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% PHS45
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This summing junction fails with two symptoms. We create a {\dc} called $SUMJUNCT$ and we can state,
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$$fm(SUMJUNCT) = \{ R1\_IN\_DOM, R2\_IN\_DOM \} $$.
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% The resistors R1, R2 form a summing junction
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% to the negative input of IC1.
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% Using the earlier definition for resistor failure modes,
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% $fm(R)= \{OPEN, SHORT\}$, we analyse the summing junction
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% in table~\ref{tbl:sumjunct} below.
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%
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% \begin{table}[h+]
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% \caption{Summing Junction: Failure Mode Effects Analysis: Single Faults} % title of Table
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% \label{tbl:sumjunct}
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%
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% \begin{tabular}{|| l | l | c | c | l ||} \hline
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% \textbf{Failure Scenario} & & \textbf{Summing} & & \textbf{Symptom} \\
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% & & \textbf{Junction} & & \\
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% \hline
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% FS1: R1 SHORT & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
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% FS2: R1 OPEN & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
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% FS3: R2 SHORT & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
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% FS4: R2 OPEN & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
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%
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% \hline
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%
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% \end{tabular}
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% \end{table}
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% % PHS45
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%
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% This summing junction fails with two symptoms. We create a {\dc} called $SUMJUNCT$ and we can state,
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% $$fm(SUMJUNCT) = \{ R1\_IN\_DOM, R2\_IN\_DOM \} $$.
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The D type flip flop
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%\subsection{FMMD Process applied to $\Sigma \Delta $ADC}.
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%\subsection{FMMD Process applied to $\Sigma \Delta $ADC}.
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T%he block diagram in figure~\ref{fig
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T%he block diagram in figure~\ref{fig
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BIN
submission_thesis/CH5_Examples/sigdel1.dia
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BIN
submission_thesis/CH5_Examples/sigdel1.dia
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@ -11,8 +11,9 @@ and apply FMEA analysis locally on this {\fg}.
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%
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%
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In this way, we determine how that {\fg} can fail.
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In this way, we determine how that {\fg} can fail.
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We can then go further and consider these to
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We can then go further and consider these to
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be symptoms of failures in the components of the {\fg}.
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be symptoms of failure of the {\fg}.
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We can collect common symptoms of failure for the {\fg}.
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Because component failures will often manifest themselves as the same symptoms of failure,
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we are able to collect common symptoms of failure for the {\fg}.
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%
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%
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%
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%
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With the collected common symptoms, we can treat the {\fg}
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With the collected common symptoms, we can treat the {\fg}
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@ -37,7 +38,7 @@ Once a hierarchy is in place, it can be converted into a fault data model.
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\fmmdgloss
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\fmmdgloss
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%
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%
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From the fault data model, automatic generation
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From the fault data model, automatic generation
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of FTA \cite{nasafta} (Fault Tree Analysis) and mimimal cuts sets \cite{nucfta} are possible.
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of FTA \cite{nasafta} (Fault Tree Analysis) and minimal cuts sets \cite{nucfta} are possible.
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Also statistical reliability/probability of failure~on~demand \cite{en61508} and MTTF (Mean Time to Failure) calculations can be produced
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Also statistical reliability/probability of failure~on~demand \cite{en61508} and MTTF (Mean Time to Failure) calculations can be produced
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automatically\footnote{Where component failure mode statistics are available \cite{mil1991}}.
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automatically\footnote{Where component failure mode statistics are available \cite{mil1991}}.
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%
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%
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@ -315,7 +316,7 @@ aircraft.}) of the failure modes to
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form `test cases'.
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form `test cases'.
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\item If required, create test cases from all valid double failure mode combinations within the {\fg}.
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\item If required, create test cases from all valid double failure mode combinations within the {\fg}.
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% \item Draw these as contours on a diagram
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% \item Draw these as contours on a diagram
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% \item Where si,ultaneous failures are examined use overlapping contours
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% \item Where simultaneous failures are examined use overlapping contours
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% \item For each region on the diagram, make a test case
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% \item For each region on the diagram, make a test case
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\item Using the `test cases' as scenarios to examine the effects of component failures,
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\item Using the `test cases' as scenarios to examine the effects of component failures,
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we determine the failure~mode behaviour of the functional group.
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we determine the failure~mode behaviour of the functional group.
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