diff --git a/submission_thesis/CH2_FMEA/copy.tex b/submission_thesis/CH2_FMEA/copy.tex index 8dcd198..91c4098 100644 --- a/submission_thesis/CH2_FMEA/copy.tex +++ b/submission_thesis/CH2_FMEA/copy.tex @@ -9,7 +9,7 @@ describes Failure Mode Effect Analysis (FMEA) as: of a system's components and determining the effects of these failures on the behaviour and safety of the system.'' \end{quotation}. - +\fmeagloss \section*{Introduction} This chapter introduces Failure Mode Effect Analysis (FMEA). %It begins with a simple example to demonstrate the basic concept of FMEA @@ -57,6 +57,7 @@ The acronym FMEA can be expanded as follows: \item \textbf{E - Effects,} Determine the effects this failure mode will cause to the system we are examining; \item \textbf{A - Analysis,} Analyse how much impact this symptom will have on the environment/operators/the system itself. \end{itemize} +\fmeagloss % FMEA is a broad term; it could mean anything from an informal check on how failures could affect some equipment in %an initial @@ -89,7 +90,7 @@ function that they perform. % demonstrate a single FMEA analysis stage, describes the four main variants of FMEA in use today % and explores some concepts with which we can discuss and evaluate % the effectiveness of FMEA. - +\fmeagloss \section{FMEA Process} We begin FMEA with the basic, or starting components. @@ -99,7 +100,7 @@ We term these the {\bcs}; they are considered ``atomic'' i.e. they are not broke % Firstly we need to know how these can fail, so our first relationship is between a {\bc} and its failure modes, see figure~\ref{fig:component_fm_rel}. - +\fmmdglossBC %DIAGRAM of Base components and failure modes \begin{figure}[h] @@ -142,7 +143,10 @@ of this chapter. \section{Determining the failure modes of {\bcs}} +\fmodegloss +\fmmdglossBC \label{sec:determine_fms} +\fmodegloss In order to apply any form of FMEA we need to know the ways in which the {\bcs} we are using can fail. In practise, this part of the process is guided by the standards to which we are seeking to conform.% to. @@ -206,7 +210,7 @@ requires statistics for Meantime to Failure (MTTF) for all {\bc} failure modes. % electronics examples for the FMMD methodology. \section{Determining the failure modes of Components.} - +\fmodegloss The starting point in the FMEA process are the failure modes of the components we would typically find in a production parts list, which we can term the {\bcs}. % @@ -228,7 +232,7 @@ European burner standard EN298~\cite{en298}. \label{sec:resistorfm} %- Failure modes. Prescribed failure modes EN298 - FMD91 \paragraph{Resistor failure modes according to FMD-91.} - +\fmodegloss The resistor is a ubiquitous component in electronics, and is therefore a good candidate for detailed examination of its failure modes. % @@ -363,7 +367,7 @@ the failure mode definitions for FMD-91 and EN298 relating to operational amplifiers are compared. \paragraph{ Failure Modes of an Op-Amp according to FMD-91 } - +\fmodegloss %Literature suggests, latch up, latch down and oscillation. For Op-Amp failures modes, FMD-91\cite{fmd91}{3-116] states, \begin{itemize} @@ -602,7 +606,7 @@ that reports its readings via RS-232. % mvamp.png: 561x403 pixel, 72dpi, 19.79x14.22 cm, bb=0 0 561 403 \caption{System diagram of a milli-volt reader, showing an expanded circuit diagram for the component of interest.} \end{figure} - +\fmeagloss @@ -633,7 +637,7 @@ For the sake of example let us choose resistor R1 in the OP-AMP gain circuitry. \item \textbf{A - Analysis} The reading will be out of the normal range, and we will have an erroneous milli-volt reading \end{itemize} - +\fmeagloss The analysis above has given us a result for one failure scenario i.e. @@ -677,7 +681,7 @@ but large and complex components (such as integrated circuits), especially where could have non mutually exclusive failure modes and these need special handling, see section~\ref{ch7:indfm}. \paragraph{The signal path.} - +\fmmdglossSIGPATH % C Garret does not like the terms afferent and efferent here, try to think of something else Most electronic systems are used to process a signal: with signal processing there is usually a clear path from the signal coming into the system, it being processed in some way, and a resultant effect on @@ -748,7 +752,7 @@ on analysis relative to the criticality of the project. Metrics from measuring the amount of work to undertake for FMEA are examined in section~\ref{sec:xfmea}. \paragraph{Failure Modes and the signal path.} - +\fmmdglossSIGPATH In general a component failure mode in an electronic circuit will change the circuit topology. For a single failure this effect may cause additional complications for the analyst. @@ -894,8 +898,9 @@ The term observable has a specific meaning in the field of control engineering~\ systems submitted for FMEA are generally related to control systems, and so to avoid confusion the terms `detectable' and `undetectable' (as defined in EN61508\cite{en61508}) will be used for describing the observability of failure modes in this document. +%\glossary{name={observability}, description={The property of a system failure in relation to a particular component failure mode, where it can be determined whether the readings/actions associated with it are valid, or the by-product of a failure. If we cannot determine that there is a fault present, the system level failure is said to be unobservable.}} +\fmmdglossOBS -\glossary{name={observability}, description={The property of a system failure in relation to a particular component failure mode, where it can be determined whether the readings/actions associated     with it are valid, or the by-product of a failure. If we cannot determine that there is a fault present, the system level failure is said to be unobservable.}} \paragraph{Impracticality of Field Data for Modern Systems.} @@ -911,9 +916,11 @@ at these reliability levels. However, we can use FMEA (more specifically the FMEDA variant, see section~\ref{sec:FMEDA}), working from known component failure rates, to obtain statistical estimates of the equipment reliability. - +\fmmdglossFIT +% \paragraph{Forward and Backward Searches.} - +\fmmdglossFS +\fmmdglossBS A forward search starts with possible failure causes and uses logic and reasoning to determine system level outcomes. Forward search types of fault analysis is said to be `inductive'. @@ -931,6 +938,7 @@ induced). \paragraph{Reasoning distance.} \label{reasoningdistance} +\fmmdglossRD A reasoning distance is the number of stages of logic and reasoning used in {\fm} analysis to map a failure cause to its potential outcomes. % @@ -982,6 +990,7 @@ If we were to examine the effect of a component {\fm} against all other componen in a system, this could be said to be exhaustive analysis. \paragraph{Exhaustive Single Failure FMEA.} +\fmmdglossXFMEA To perform FMEA exhaustively (i.e. to examine every possible interaction of a failure mode with all other components in a system). Or in other words, ---we would need to look at all possible failure scenarios. @@ -1002,8 +1011,7 @@ to undertake an `exhaustive~FMEA'. Even small systems have typically $100*99*3=29,700$ as a reasoning distance. \paragraph{Exhaustive FMEA and double failure scenarios.} - - +% %\paragraph{Exhaustive Double Failure FMEA} For looking at potential double failure scenarios\footnote{Certain double failure scenarios are already legal @@ -1065,9 +1073,8 @@ is given in section~\ref{sec:resistortolerance}. \section{PFMEA - Production FMEA : 1940's to present} - - - +\fmmdglossPFMEA +% Production FMEA (or PFMEA), is FMEA used to prioritise, in terms of cost, problems to be addressed in product production. % @@ -1096,7 +1103,7 @@ will return most cost benefit~\cite{bfmea}. \section{FMECA - Failure Modes Effects and Criticality Analysis} - + \fmmdglossFMECA \paragraph{ FMECA - Failure Modes Effects and Criticality Analysis.} % \begin{figure} % \centering @@ -1194,6 +1201,8 @@ and require re-design of some systems. \subsection{ FMEDA - Failure Modes Effects and Diagnostic Analysis} % +\fmmdglossFMEDA +% \begin{table}[ht] \centering @@ -1256,7 +1265,7 @@ and have measures in place to reduce their affects. % In EN61508 terminology, a safety~loop is known as a Safety Instrumented Function (SIF). % - +\fmmdglossFMEDA % % for four levels of %safety integrity, referred to as Safety Integrity Levels (SIL). @@ -1279,7 +1288,7 @@ or across the software/hardware interface. % While procedural guidelines and constraints can improve software reliability, ensuring that reliability targets, for software, are actually met for given SIL levels is currently almost impossible~\cite{silsandsoftware}. - +\fmmdglossFMEDA %\subsection{ FMEDA - Failure Modes Effects and Diagnostic Analysis} \label{sec:FMEDA} @@ -1314,7 +1323,7 @@ the percentage of dangerous detected base component failure modes, and $\Sigma\lambda_D$ the total number of dangerous base component failure modes. $$ DiagnosticCoverage = \Sigma\lambda_{DD} / \Sigma\lambda_D $$ - +\fmmdglossFMEDA @@ -1340,7 +1349,7 @@ $$ SFF = \big( \Sigma\lambda_S + \Sigma\lambda_{DD} \big) / \big( \Sigma\lambda_ SFF determines how proportionately fail-safe a system is, not how reliable it is. A weakness in this philosophy; adding extra safe failures (even unused ones) would improve the apparent SFF, this apparent loophole is closed in the 2010 edition of the standard. - +\fmmdglossFMEDA @@ -1349,7 +1358,7 @@ To achieve SIL levels, diagnostic coverage and SFF levels are prescribed along w hardware architectures and software techniques. The overall aim of SIL is to classify the safety of a system, by statistically determining how frequently it can fail dangerously. - +\fmmdglossFMEDA @@ -1367,7 +1376,7 @@ by statistically determining how frequently it can fail dangerously. %part of product approval for many regulated products in the EU and the USA... \section{FMEA used for Safety Critical Approvals} - +\fmmdglossDFMEA \subsection{DESIGN FMEA: Safety Critical Approvals FMEA} \begin{figure}[h] \centering @@ -1433,7 +1442,7 @@ relating this to the signal path or adjacency in the electronic circuit, among w \item Look at all components in the system. \end{itemize} No current variant of FMEA gives any guidelines for which, or how many components to check for a given {\fm}. - +\fmmdglossRD \paragraph{FMEA gives us objective system level failures/symptoms, what do we do with subjective or contextual failures resulting from this?} The two more modern variants of FMEA, FMECA and FMEDA start to address the problem of subjective/contextual failure symptoms of a system. diff --git a/submission_thesis/CH3_FMEA_criticism/copy.tex b/submission_thesis/CH3_FMEA_criticism/copy.tex index ba8a437..5b66e26 100644 --- a/submission_thesis/CH3_FMEA_criticism/copy.tex +++ b/submission_thesis/CH3_FMEA_criticism/copy.tex @@ -13,6 +13,7 @@ Legally mandatory FMEA for a large proportion of safety critical systems in Europe and the USA, at the very least means that experienced engineers have to discuss a system at a level of detail starting at {\bc} {\fms}. +\fmmdglossBC % This undoubtedly reveals dangers inherent in designs and makes our lives safer. This chapter aims to look for the deficiencies in current FMEA processes, to probe for weaknesses @@ -184,7 +185,7 @@ failure models are discussed in ~\cite{SMR:SMR580,swassessment}. \paragraph{Current work on Software FMEA.} - +\fmmdglossSFMEA SFMEA usually does not seek to integrate hardware and software models, but to perform FMEA on the software in isolation~\cite{procsfmea}. @@ -222,6 +223,7 @@ using a communications protocol, similarly are difficult to meaningfully analyse \subsection{The rise of the smart instrument} \label{sec:smart} +\fmmdglossSMARTINSTRUMENT %% AWE --- Atomic Weapons Establishment have this problem.... A smart instrument is defined as one that uses a micro-processor and software in conjunction with its sensing electronics, rather than diff --git a/submission_thesis/CH7_Evaluation/copy.tex b/submission_thesis/CH7_Evaluation/copy.tex index 978f9ae..5f76ace 100644 --- a/submission_thesis/CH7_Evaluation/copy.tex +++ b/submission_thesis/CH7_Evaluation/copy.tex @@ -9,6 +9,7 @@ a metric for the complexity of an FMEA analysis task. % This concept is called `comparison~complexity' and is a means to assess the performance of FMMD against current FMEA methodologies. +\fmmdglossRD % This metric is developed using set theory % formally and then formulae are presented for calculating the @@ -24,6 +25,7 @@ goes from a polynomial to a logarithmic order comparing XFMEA with FMMD. % The reasoning distances obtained from the FMMD examples (see chapter~\ref{sec:chap5}) are compared against {\XFMEA}. +\fmmdglossXFMEA % Following on from the formal definitions, `unitary state failure modes' are defined. In short these ensure that component failure modes are mutually exclusive. % Using the unitary state failure mode definition @@ -56,6 +58,7 @@ This is followed by some critiques of FMMD. % in use.%i.e. possible areas of dif \section{Defining the concept of `comparison~complexity' in FMEA} +\fmmdglossRD \label{sec:cc} % % DOMAIN == INPUTS @@ -109,6 +112,8 @@ This would mean we would be %looking examining for all possible side effects that a base component failure could cause. % We could term this `exhaustive~FMEA'~({\XFMEA}). +\fmmdglossXFMEA +\fmmdglossRD The number of checks we have to make to achieve this, gives an indication of the complexity of the analysis task. % %This is described in section~\ref{sec:rd}, where the reasoning distance, or complexity to @@ -117,7 +122,7 @@ The number of checks we have to make to achieve this, gives an indication of the % %It is desirable to be able to measure the complexity of an analysis task. % -We define comparison~complexity as the count of +We define comparison~complexity (or reasoning~distance) as the count of paths between failure modes and components necessary to achieve {\XFMEA} for a given group of components $G$. %system or {\fg}. @@ -209,6 +214,7 @@ An FMMD hierarchy consists of many {\fgs} which are subsets of $G$. %$$ \forall FG \in \mathcal{FG} | FG \subset \mathcal{G} .$$ % FMMD analysis creates a hierarchy $\hh$ of {\fgs}. % where $\hh \subset \mathcal{FG}$. +\fmmdgloss % We can define individual {\fgs} using $FG^{\alpha}_{i}$ with an index $i$ for identification and a superscript for the $\alpha$~level (see section~\ref{sec:alpha}). @@ -268,6 +274,7 @@ We overload the comparison complexity function $CC$, to obtain the comparison co \subsection{Complexity Comparison Examples} \label{sec:theoreticalperfmodel} +\fmmdglossRD %\pagebreak[4] We initially work through the amplifier example from chapter~\ref{sec:chap4}, which has two stages, the potential divider and then the amplifier. We add the complexities from @@ -340,7 +347,7 @@ process are by-hand/human activities. It can be seen that it is practically impo \subsection{Comparing FMMD and {\XFMEA} Comparison Complexity} - +\fmmdglossRD Because components have variable numbers of failure modes, and {\fgs} have variable numbers of components, it is difficult to use the general formula for comparing the number of checks to make for @@ -381,7 +388,7 @@ the number of failure modes per component to three, an FMMD hierarchy would look like figure~\ref{fig:three_tree}. \subsection{Comparing {\XFMEA} and FMMD: an Example} - +\fmmdglossXFMEA Using the diagram in figure~\ref{fig:three_tree}, we have three levels of analysis. % Starting at the top, we have a {\fg} with three derived components, each of which has diff --git a/submission_thesis/CH8_Conclusion/copy.tex b/submission_thesis/CH8_Conclusion/copy.tex index 8315ea4..c1bbc97 100644 --- a/submission_thesis/CH8_Conclusion/copy.tex +++ b/submission_thesis/CH8_Conclusion/copy.tex @@ -1,5 +1,5 @@ \label{sec:chap8} - +\fmeagloss This study has examined the processes and state of the art of the four main FMEA variants. % It has exposed shortcomings in these methodologies, which can be summed up as an inability to @@ -96,6 +96,8 @@ These are presented below. %This section describes areas that the study has revealed where the FMMD methodology may be extended or improved. \subsection{How traditional FMEA reports can be derived from an FMMD model.} % +\fmmdgloss +\fmeagloss An FMMD model has a data structure (described by UML diagrams, see figure~\ref{fig:cfg}), and by traversing an FMMD hierarchy we can map system level failures back to {\bc} {\fms} (or combinations thereof). % @@ -161,12 +163,9 @@ failure statistics, we calculate the reliability of the Pt100 example (see secti The formula given in MIL-HDBK-217F\cite{mil1991}[9.2] for a generic fixed film non-power resistor is reproduced in equation \ref{resistorfit}. The meanings and values assigned to its co-efficients are described in table \ref{tab:resistor}. -\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular -failure is expected to occur in a $10^{9}$ hour time period.}} - - +\fmmdglossFIT \fmodegloss - +% \begin{equation} % fixed comp resistor{\lambda}_p = {\lambda}_{b}{\pi}_{R}{\pi}_Q{\pi}_E resistor{\lambda}_p = {\lambda}_{b}{\pi}_{R}{\pi}_Q{\pi}_E @@ -174,7 +173,7 @@ resistor{\lambda}_p = {\lambda}_{b}{\pi}_{R}{\pi}_Q{\pi}_E \end{equation} \begin{table}[ht] -\caption{Fixed film resistor Failure in time assessment} % title of Table +\caption{Fixed film resistor Failure In Time (FIT) assessment.} % title of Table \centering % used for centering table \begin{tabular}{||c|c|l||} \hline \hline @@ -253,8 +252,9 @@ Thus thermistor, bead type, `non~military~spec' is given a FIT of 315.0 % Using the RIAC finding we can draw up the following table (table \ref{tab:stat_single}), showing the FIT values for all faults considered. -\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular failure is expected to occur in a $10^{9}$ hour time period.}} - +%\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular failure is expected to occur in a $10^{9}$ hour time period.}} +\fmmdglossFIT +% \begin{table}[h+] \caption{Pt100 FMEA Single // Fault Statistics} % title of Table \centering % used for centering table @@ -281,15 +281,15 @@ TC:6 $R_2$ OPEN & High Fault & High Fault & 12.42 \\ \hline The FIT for the circuit as a whole is the sum of MTTF values for all the test cases. The Pt100 circuit here has a FIT of 342.6. This is a MTTF of about 360 years per circuit. - +% A probabilistic tree can now be drawn, with a FIT value for the Pt100 circuit and FIT values for all the component fault modes from which it was calculated. We can see from this that the most likely fault is the thermistor going OPEN. This circuit is around 10 times more likely to fail in this way than in any other. Were we to need a more reliable temperature sensor, this would probably be the fault~mode we would scrutinise first. - - +% +% \begin{figure}[h+] \centering \includegraphics[width=400pt,bb=0 0 856 327,keepaspectratio=true]{./CH5_Examples/stat_single.png} @@ -297,8 +297,7 @@ be the fault~mode we would scrutinise first. \caption{Probablistic Fault Tree : Pt100 Single Faults} \label{fig:stat_single} \end{figure} - - +% The Pt100 analysis presents a simple result for single faults. The next analysis phase looks at how the circuit will behave under double simultaneous failure conditions. @@ -338,8 +337,9 @@ This means that should we wish to cope with this fault, we need to devise a new way of detecting this condition, perhaps in higher levels of the system/FMMD hierarchy. % -\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular failure is expected to occur in a $10^{9}$ hour time period. Associated with continuous demand systems under EN61508~\cite{en61508}}} +%\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular failure is expected to occur in a $10^{9}$ hour time period. Associated with continuous demand systems under EN61508~\cite{en61508}}} % +\fmmdglossFIT % \subsection{Deriving FTA diagrams from FMMD models} \label{sec:fta} diff --git a/submission_thesis/appendixes/algorithmic.tex b/submission_thesis/appendixes/algorithmic.tex index efec50d..5113f98 100644 --- a/submission_thesis/appendixes/algorithmic.tex +++ b/submission_thesis/appendixes/algorithmic.tex @@ -14,14 +14,6 @@ The intention for defining FMMD in algorithmic and set theoretic terms is to pro a solid specification for the process that could guide a software implementation.% for it. -\fmodegloss - -\glossary{name={system}, description={A product designed to work as a coherent entity}} -\glossary{name={sub-system}, description={A part of a system, sub-systems may contain sub-systems and so-on}} -\glossary{name={{\dc}}, description={A theoretical component, derived from a collection of components (which may be derived components themselves)}} -\glossary{name={{\fg}}, description={A collection of sub-systems and/or components that interact to perform a specific function}} -\glossary{name={symptom}, description={A failure mode of a {\fg}, caused by a combination of its component failure modes}} -\glossary{name={base component}, description={Any bought in component, or lowest level module/or part}} %\glossary{name={entry name}, description={entry description}} @@ -37,6 +29,7 @@ The FMMD process is described in chapter~\ref{sec:chap4}. \item creating a {\dc} representing the failure mode behaviour of the {\fg}. \end{itemize} % +\fmmdgloss %This is termed `symptom~abstraction'. % TO DO: separate these two: % @@ -80,7 +73,7 @@ each test case. %which has its own FMMD defined set of failure modes. % symptoms. % %The designer can now treat this module as a black box (i.e. as a {\dc}). - +\fmmdgloss \paragraph{Environmental Conditions or Operational States.} % Each test case must also be considered for all %applied/ @@ -107,6 +100,7 @@ These results can be viewed as symptoms of failure of the {\fg}. \paragraph{Collection of Symptoms.} +\fmmdgloss %Looking at the % examining failure from the % functional group perspective failure modes, we collect @@ -147,7 +141,7 @@ It is possible here for an automated system to flag un-handled failure modes. %\paragraph{To analyse a base level Derived~Component/sub-system} The expanded FMMD process can now be described in five steps: - +\fmmdgloss \begin{enumerate} \item Choose a set of components to form a {\fg}, and collect the failure modes of each component in the {\fg} into a flat set. %% COLLECT FAILURE MODES \item Choose all single instances (and optional selected combinations\footnote{ %% DETERMINE TEST CASES @@ -197,7 +191,7 @@ that will be used in the algorithmic description of FMMD. % Let the set of all possible components be $\mathcal{C}$ and let the set of all possible failure modes be $\mathcal{F}$ and $\mathcal{P}$ the powerset. - +\fmmdgloss We can define a function $fm$ which returns the failure modes for a given component (see section~\ref{sec:formal7}): \begin{equation} @@ -293,7 +287,7 @@ The checks and constraints applied in the algorithm ensure that all component fa modes are covered. This process provides the analysis `step' to building a hierarchical failure mode model from the bottom-up. - +\fmmdgloss @@ -526,7 +520,7 @@ the {\fg}, not the members of it i.e. the components. % failure modes. Thus we will have a set of results corresponding to our test cases. These share a common index value ($j$ in the algorithm description). These results are the failure modes of the {\fg}. - +\fmmdgloss %Once a functional group has been analysed, it can be re-used in %any other design that uses it. %Often safety critical designs have repeated sections (such as safety critical digital inputs or $4\rightarrow20mA$ @@ -621,7 +615,7 @@ component created in the next stage. Ensuring that no result belongs to more than one symptom set enforces the `unitary state failure mode constraint' for derived components (see section~\ref{sec:unitarystate}). } - +\fmmdgloss %% Interesting to draw a graph here. %% starting with components, branching out to failure modes, then those being combined to %% test cases, the test cases producing results, and then the results collected into @@ -738,7 +732,7 @@ minimal cut sets\cite{nasafta} or entire FTA trees\cite{nucfta}, and by analysing the statistical likelihood of the component failures, the Mean Time to Failure (MTTF) and Failure in Time(FIT)\cite{en61508} levels can be automatically calculated. - +\fmmdgloss %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % diff --git a/submission_thesis/style.tex b/submission_thesis/style.tex index b7e8bca..ddcb9bc 100644 --- a/submission_thesis/style.tex +++ b/submission_thesis/style.tex @@ -70,11 +70,58 @@ \newcommand{\wrt}{\emp with~respect~to} \newcommand{\swf}{software~function} % DO NOT USE THIS ONE USE \abslev \newcommand{\abslevel}{\ensuremath{\Psi}} -\newcommand{\fmmdgloss}{\glossary{name={FMMD},description={Failure Mode Modular De-Composition, a bottom-up methodolgy for incrementally building failure mode models, using a procedure taking functional groups of components and creating derived components representing them, and in turn using the derived components to create higher level functional groups, and so on, that are used to build a failure mode model of a SYSTEM}}} + + +%% GLOSSARY FORMAT +% +% \newcommand{\fmmdname}{\glossary{name={FMMDNAME},description={ }} + +%\fmodegloss + +\newcommand{\fmmdglossSYS}{\glossary{name={system}, description={A product designed to work as a coherent entity}}} +\newcommand{\fmmdglossSS}{\glossary{name={sub-system}, description={A part of a system, sub-systems may contain sub-systems and so-on}}} +\newcommand{\fmmdglossDC}{\glossary{name={{\dc}}, description={A theoretical component, derived from a collection of components (which may be derived components themselves)}}} +\newcommand{\fmmdglossFG}{\glossary{name={{\fg}}, description={A collection of sub-systems and/or components that interact to perform a specific function}}} +\newcommand{\fmmdglossSYMPTOM}{\glossary{name={symptom}, description={A failure mode of a {\fg}, caused by a combination of its component failure modes}}} +\newcommand{\fmmdglossBC}{\glossary{name={base component}, description={Any bought in component, or lowest level module/or part}}} + + + +%\newcommand{\fmmdglossFIT}{\glossary{name={FIT},description={Failure in Time (FIT). The statistical likelihood of failure mode occurring within a $10^9$ hour period.}} +\newcommand{\fmmdglossFIT}{\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular +failure is expected to occur within a $10^{9}$ hour time period.}}} + +\newcommand{\fmmdglossHFMEA}{\glossary{name={HFMEA},description={Hardware FMEA. FMEA applied to hardware i.e. mechanical or electrical equipment.}}} +\newcommand{\fmmdglossSFMEA}{\glossary{name={SFMEA},description={Software FMEA. FMEA techniques applied to software. }}} +\newcommand{\fmmdglossXFMEA}{\glossary{name={XFMEA},description={Exhaustive FMEA. Each failure mode is checked for effects on all components in a given system. }}} +\newcommand{\fmmdglossDFMEA}{\glossary{name={DFMEA},description={Design FMEA. FMEA applied in design stages of a product. Used as a discussion method to reveal safety weakness and improve built in safety.}}} +\newcommand{\fmmdglossPFMEA}{\glossary{name={PFMEA},description={Production FMEA. FMEA applied applied for cost benefit analysis typically used in mass production.}}} +\newcommand{\fmmdglossSFTA}{\glossary{name={SFTA},description={Software Fault Tree Analysis (SFTA): top down failure investigation applied to software.}}} +\newcommand{\fmmdglossFTA}{\glossary{name={FTA},description={Fault Tree Analysis (FTA). A top down failure analysis technique which starts with undesirable top level events and works downwards to putative causes.}}} +\newcommand{\fmmdglossFMEDA}{\glossary{name={FMEDA},description={Failure Mode Effects and Diagnostic Analysis (FMEDA). An extended FMEA technique which provides for diagnostic mitigation and has a final statistical safety level as a result.}}} +\newcommand{\fmmdglossFMECA}{\glossary{name={FMECA},description={Failure Mode Effects and Criticality Analysis (FMECA). An extended FMEA technique which is used to order the severity or criticality of top level events/symptoms.}}} +\newcommand{\fmmdglossFS}{\glossary{name={forward~search},description={Failure analysis where the start points are base component failure modes and the result is system level failure/symptom.}}} +\newcommand{\fmmdglossBS}{\glossary{name={backward~search},description={Failure analysis where the start points are system level failure/symptom and the results are lower level putative causes.}}} +\newcommand{\fmmdglossINHIBIT}{\glossary{name={inhibit},description={A guard on a process such that if a condition is not met, the process may not continue.}}} +\newcommand{\fmmdglossSIGPATH}{\glossary{name={signal~path},description={The components (software or hardware) and connections that a particular signal or value is derived from in a system.}}} +\newcommand{\fmmdglossRD}{\glossary{name={reasoning~distance},description={A reasoning distance is the number of stages of logic and reasoning, counted by the number of components examined, used to map a failure cause to its potential outcomes.}}} +\newcommand{\fmmdglossOBS}{\glossary{name={observability}, description={If it cannot be detected that a failure has occurred it is termed unobservable or undetectable.}}} + +\newcommand{\fmmdglossSMARTINSTRUMENT}{\glossary{name={smart~instrument}, description={ +A smart instrument is defined as one that uses software +in conjunction with its sensing electronics, rather than +analogue electronics only~\cite{smart_instruments_1514209}.}}} +% +%\newcommand{\fmmdglossRD}{\glossary{name={reasoning~distance}{yahda yahda ya}}} +% +\newcommand{\fmmdgloss}{\glossary{name={FMMD},description={Failure Mode Modular De-Composition (FMMD). a bottom-up methodology for incrementally building +failure mode models, using a procedure taking functional groups of components and creating derived components representing them, and in turn using the +derived components to create higher level functional groups, and so on, that are used to build a hierarchical failure mode model of a system}}} \newcommand{\fmodegloss}{\glossary{name={failure mode},description={The way in which a failure occurs. A component or sub-system may fail in a number of ways, and each of these is a -failure mode of the component or sub-system}}} -\newcommand{\fmeagloss}{\glossary{name={FMEA}, description={Failure Mode and Effects analysis (FMEA) is a process where each potential failure mode within a SYSTEM, is analysed to determine SYSTEM level failure modes, and to then classify them {\wrt} perceived severity}}} -\newcommand{\frategloss}{\glossary{name={failure rate}, description={The number of failure within a population (of size N), divided by N over a given time interval}}} +failure mode of the component or sub-system.}}} +\newcommand{\fmeagloss}{\glossary{name={FMEA}, description={Failure Mode and Effects analysis (FMEA) is a process where each failure mode of components in a given system, +is analysed to determine system level failures/symptoms.}}} +\newcommand{\frategloss}{\glossary{name={failure rate}, description={The number of failures within a population (of size N), divided by N over a given time interval}}} \newcommand{\pecgloss}{\glossary{name={PEC},description={A Programmable Electronic controller, will typically consist of sensors and actuators interfaced electronically, with some firmware/software component in overall control}}} \usepackage{amsthm}