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Wydanie dofinansowane przez Ministra Nauki i Szkolnictwa Wy szego
- Antoni Sowa
- 1 lat temu
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2 prof. dr hab. in. Jan ADAMCZYK AGH w Krakowie dr in. Roman BARCZEWSKI Politechnika Pozna ska prof. dr hab. in. Walter BARTELMUS Politechnika Wroc awska prof. dr hab. in. Wojciech BATKO AGH w Krakowie prof. dr hab. in. Les aw B DKOWSKI WAT Warszawa prof. dr hab. in. Adam CHARCHALIS Akademia Morska w Gdyni prof. dr hab. in. Wojciech CHOLEWA Politechnika l ska prof. dr hab. in. Zbigniew D BROWSKI Politechnika Warszawska prof. dr hab. in. Marian DOBRY Politechnika Pozna ska RADA PROGRAMOWA PRZEWODNICZ CY: prof. dr hab. dr h.c. mult. Czes aw CEMPEL Politechnika Pozna ska REDAKTOR NACZELNY: prof. dr hab. in. Ryszard MICHALSKI UWM w Olsztynie prof. Wiktor FRID Royal Institute of Technology in Stockholm Szwecja dr in. Tomasz GA KA Instytut Energetyki w Warszawie prof. dr hab. in. Jan KICI SKI IMP w Gda sku prof. dr hab. in. Jerzy KISILOWSKI Politechnika Warszawska prof. dr hab. in. Daniel KUJAWSKI Western Michigan University USA CZ ONKOWIE: prof. dr hab. Wojciech MOCZULSKI Politechnika l ska prof. dr hab. in. Stanis aw NIZI SKI UWM w Olsztynie prof. Vasyl OSADCHUK Politechnika Lwowska Ukraina prof. dr hab. in. Stanis aw RADKOWSKI Politechnika Warszawska prof. Bob RANDALL University of South Wales Australia prof. dr Raj B. K. N. RAO President COMADEM International Anglia prof. Vasily S. SHEVCHENKO BSSR Academy of Sciences Mi sk Bia oru prof. Menad SIDAHMED University of Technology Compiegne Francja prof. dr hab. in. Tadeusz UHL AGH w Krakowie prof. Vitalijus VOLKOVAS Kaunas University Litwa prof. dr hab. in. Andrzej WILK Politechnika l ska dr Gajraj Singh YADAVA Indian Institute of Technology Indie prof. Alexandr YAVLENSKY Aerospace University Sankt Petersburg Rosja prof. dr hab. in. Bogdan Ó TOWSKI UTP w Bydgoszczy Wszystkie opublikowane prace uzyska y pozytywne recenzje wykonane przez niezale nych recenzentów. Obszar zainteresowania czasopisma to problemy diagnostyki, identyfikacji stanu technicznego i bezpiecze stwa maszyn, urz dze, systemów i procesów w nich zachodz cych. Drukujemy oryginalne prace teoretyczne, aplikacyjne, przegl dowe z bada, innowacji i kszta cenia w tych zagadnieniach. WYDAWCA: Polskie Towarzystwo Diagnostyki Technicznej Warszawa ul. Augustówka 5 REDAKTOR NACZELNY: prof. dr hab. in. Ryszard MICHALSKI SEKRETARZ REDAKCJI: dr in. S awomir WIERZBICKI CZ ONKOWIE KOMITETU REDAKCYJNEGO: dr in. Krzysztof LIGIER dr in. Pawe MIKO AJCZAK ADRES REDAKCJI: Uniwersytet Warmi sko Mazurski w Olsztynie Katedra Budowy, Eksploatacji Pojazdów i Maszyn Olsztyn, ul. Oczapowskiego 11 tel.: , fax: KONTO PTDT: Bank Przemys owo Handlowy S.A. II O/ Warszawa nr konta: NAK AD: 25 egzemplarzy Wydanie dofinansowane przez Ministra Nauki i Szkolnictwa Wy szego
3 DIAGNOSTYKA 1 (41)/27 Spis Tre ci Nadim OBEID The University of Jordan, Raj B.K.N. RAO COMADEM International...5 A Step Toward A Universal Theory Of Failure Handling Marek WYLE O Politechnika l ska...15 Reverse Engineering In Applications To Modal Analysis Of Virtual Models In ynieria odwrotna w zastosowaniu do analizy modalnej modeli wirtualnych Zdzis aw H. KLIM Bombardier Aerospace Montréal, Pawe SZCZEPA SKI WAT Warszawa, Marek BA AZI SKI École Polytechnique of Montréal...19 Causes And Effects Of Cascading Failures In Aircraft Systems Przyczyny i skutki niezdatno ci kaskadowych w systemach samolotu Wojciech BATKO, Tomasz KORBIEL AGH Kraków...27 Badania zbrojenia szybowego w oparciu o globalny wspó czynnik t umienia Testing Of Shaft Reinforcement Using Global Attenuation Coefficient Marek ZBOI SKI ITWL Warszawa...39 Modelowanie i identyfikacja wp ywu kontaminacji cieczy roboczej na trwa o instalacji hydraulicznych statków powietrznych Modelling And Evaluation Of Effects Of Working Liquid s Contamination Upon Aircraft Hydraulic Units Life Tomasz BURNOS Akademia Morska w Szczecinie...45 Wp yw obci enia chwilowego na proces diagnozowania agregatów typu ster strumieniowy The Impact Of Temporary Load On Thruster Condition Monitoring Process Zbigniew DAMIJAN AGH Kraków...49 Badanie wp ywu niskocz stotliwo ciowego pola magnetycznego (f=7 Hz, B=33 nt) na wybrane parametry elektrofizjologiczne organizmu The Effects Of Low-Frequency Magnetic Field (f =7 Hz, B=33 nt) Exposure On Selected Physiological Parameters Of Human Body Zbigniew DAMIJAN AGH Kraków...55 Badanie wp ywu ekspozycji niskocz stotliwo ciowego pola magnetycznego (f=7 Hz, B=33 nt) na czynno bioelektryczn serca The Effects Of Low-Frequency Magnetic Filed Exposure (f=7 Hz, B=33 nt) On The Level Of Bioelektric Activity Of Human Heart Stanis aw Janusz CIE LAKOWSKI Politechnika Radomska...61 Diagnozowanie bezpiecze stwa wagonów kolejowych w systemach rozrz dzania grawitacyjnego Diagnostics Of Rail Carriage Safety In Gravitational Marshalling Systems Micha HANZEL, Wojciech MOCZULSKI Politechnika l ska...81 System diagnostyki ma ych silników pr du sta ego z wykorzystaniem metody identyfikacji System Of Diagnostics Of Small DC Motors With The Usage Of Identification Method Józef GRZYBOWSKI, Tomasz ROGALSKI, Pawe RZUCID O Politechnika Rzeszowska...75 Pok adowy system rejestracji PSR-4E On-Board Data Acquisition System PSR-4E Andrzej PUCHALSKI Politechnika Radomska...81 Monitoring pok adowy mechatronicznych uk adów bezpiecze stwa pojazdu. Tendencje Monitoring Of Motor Vehicle s Mechatronic Safety Systems. Trends Piotr BIELAWSKI Akademia Morska w Szczecinie...85 Model zarz dzania obs ugiwaniem maszyn okr towych systemów nap dowych The Model Of Maintenance Management Of Machines Of Ship Propulsion Systems
4 4 DIAGNOSTYKA 1 (41)/27 SPIS TRE CI Walter BARTELMUS, Rados aw ZIMROZ, Wojciech SAWICKI Politechnika Wroc awska...91 Wp yw zmiennych warunków eksploatacji na proces oceny stanu przek adni planetarnych w uk adach nap dowych ko a czerpakowego koparek ko owych Influence Of Operational Condition To Diagnostic Process Of Planetary Gearbox In Driving System Used In Bucket Wheel Excavator Eugeniusz GRUDZI SKI Politechnika Wroc awska, Witalij NICZOGA, Ivan PRUDYUS Politechnika Lwowska...11 Diagnozowanie i monitoring struktur promieniuj cych pod k tem zagro e stwarzanych dla aparatury i ludzi Diagnostics And Monitoring Of Radiating Sources Regarding Hazards For People And Equipment Warto przeczyta...11
5 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 5 A STEP TOWARD A UNIVERSAL THEORY OF FAILURE HANDLING Nadim OBEID *, Raj B. K. N. RAO ** *Department of Computer Information Systems, King Abdullah School for Information Technology, The University of Jordan, JORDAN **COMADEM International, 37 Tiverton Road, Selly Oak, Birmingham B29 6DA, UK Summary We explore, in this paper, some of the fundamental requirements needed for a Universal Theory of Failure Handling. We shall show that dealing with failure touches on our reasoning, predictive, evaluative and judgmental capabilities and thus it requires the ability to reason with incomplete and uncertain temporal information. It also requires reasoning with events before they even happen and about the effect of actions for as long as these are relevant, even if the available time does not permit. There may also be a need for reasoning about the reasoning process itself. We shall discuss the notion of failure with respect to decision-making and knowledge. We give a very brief presentation of Dorner s logic of failure and research into artificial intelligence and its implication for handling failures. We shall propose means of computing the degrees of failure induced by humans and in physical systems. In addition, we shall initiate a discussion on reasoning with failures and put forward a proposal for an integrative and proactive approach to monitoring, diagnosis and learning from failures. Keywords: logic, failure, reasoning, decision-making, learning, diagnosis, monitoring, time, event, nonmonotonic. 1. INTRODUCTION Failure seems to be a fact of life and almost every human endeavor (whether it is in business, politics, medical, defence, science, engineering, technology and management) has its way cemented by layers of failures (Rao (26). It is everyone's ultimate goal to minimize the effect(s) of failure and to avoid, if at all possible. This phenomenon is shared by every discipline and/or every field of study and the patterns of behaviour to avoid or counter the effects of failure are quite similar. In addition to understanding a system, dealing with failure touches on our reasoning, predictive, evaluative and judgmental capabilities. It requires the ability to reason: 1. With incomplete and uncertain temporal information. 2. With events before they even happen. 3. About the effect of actions for as long as these are relevant and even if the available time does not permit. 4. About the reasoning process. We aim, in this paper, to explore some of the requirements needed for a Universal Theory of Failure Handling. Section 2 is concerned with the notion of failure with respect to decision-making and knowledge. In section 3 we present a brief review of Dorner's logic of failure. Section 4 is concerned with research in artificial Intelligence and its implication for failure handling. In sections 5 and 6 we propose means of computing the degrees of failure by humans and in physical systems respectively. In section 7 we discuss the notion of reasoning failure. In section 8 we put forward a proposal for an integrative and proactive approach to monitoring, diagnosis and learning from failures. 2. FAILURE WITH RESPECT TO DECISION- MAKING AND KNOWLEDGE A decision is a choice of an action from a set of alternative actions. Despite its long history and the interdisciplinary interest in this topical area, decision theory has nothing to say about the nature of actions and how they may become available. One of the key issues that must be properly tackled is what makes a good decision. They are formally characterized as actions that maximize expected utility. This view presumes that every action is associated with some outcome(s) and it is the responsibility of the decision maker to decide the nature of the outcome. However, there is some doubt about the validity of the utility-based approach regarding the possibility of estimating the outcome of actions (especially over long periods of time) (cf. Hare (1963)). There are many complex situations/scenarios that require the reasoner to have the ability to formulate decisions in unforeseen circumstances and to change the assumptions that underlie decisions. The adequacy of the required information is decided by the criteria of preference employed by the decision maker. Decisions that satisfy the conditions of ideal rationality may not have the opportunity to be made.
6 6 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling This is partly because, even with coherent preferences, it may take longer than permitted to obtain the relevant information or to decide what is reasonable. Thus, decisions may have to be made with incomplete information. Furthermore, information not vindicated by the preference criteria may not be considered even if it is relevant to the decision(s). Practical reasoning is a complicated process. Human-based systems have theories or perceptions of the world, learn new information which may lead them to update their theories, make decisions using the acquired knowledge, have definite goals and intentions, and may act based on some of the decisions. It is important to note that each of these steps is susceptible to failure. The world-view may be false. Even if beliefs are true, decisions may be inappropriate and action may fail. Any of these `failure modes' can have a contributory role in a causal chain leading to a failure. Failure occurs even in simple mundane tasks. The reasons for failure are numerous. Some of these reasons, just to mention a few, are: 1. Failure to check the appropriate information before acting. 2. Failure to check the availability of resources before a plan is carried out. 3. Making (inaccurate) assumptions and not reevaluating their validity before acting. 4. Failure to consider other equally viable alternatives. 5. Failure to check for the correct order of a sequence of actions. In complex situations and dealing with large complex systems, the tendency of losing sight/control is even greater. Some of the characteristics of decision-making in complex systems/situations are: 1. A failure in a complex system may not be detectable for long periods. 2. Complex systems/situations are difficult to evaluate. 3. A complex system can fail in numerous ways (multicausal). 4. The mode of failure of a complex system/situation is not easily predictable. 5. The crucial variables in a complex system/situation are not easily identifiable. 6. The more complex the system/situation, the greater is the possibility of unexpected failure. 7. Sometimes ideas are expressed poorly or are so complicated that those outside the group fail to challenge it because they may be seen as stupid for not understanding it in the first place. 8. An incorrect assumption leads to incorrect conclusion or decision. In many situations, incomplete or misleading information may even become the norm. Assuming a piece of evidence just to force the conclusion to fit the facts is seldom correct. This only results in more accumulated failures or in passing the buck to wrong individuals. 9. Most industrial accidents result either from human behaviour, such as bypassing safety devices or failing to ensure that a machine is in a safe state before entering a hazardous zone, or from systematic failures, such as incorrect selection of safety devices. In some situations humans can be the worst of the worst. 1. The more the world grows nano, the more the challenge becomes macro. 11. To understand the root causes of failure, it is important to comprehend the underlying reasoning and decision-making processes and why they sometimes fail miserably. The processes depend to a large degree on certain, correct and complete information and knowledge. However, certainty and correctness of information may need to be established and new knowledge may have to be discovered, generated and disseminated. Reasoning and decision-making are closely associated with the gathering of the unbiased data and with the principles of accessing, manipulating and continuously evaluating intelligently different alternatives in order to choose the most appropriate for a given situation. Logic of different kinds is needed in order to correctly evaluate and manipulate information and knowledge. Logic is the ability, which allows us to generate knowledge from information. Development of meta-diagnosis through meta-knowledge will pave the way to successfully deal with failures. 3. THE LOGIC OF FAILURE Dorner (1997) concluded that more often than not, humans completely fail to effectively manage complex systems. He states that: 1. Due to the slowness of our processing of conscious thought, we tend to make shortcuts in our decision-making (e.g, act before we have clearly defined what our goal is, or collected the required information). 2. We tend to oversimplify our models of complex systems by focusing only on one or two key variables and underestimating the importance of other interacting factors. 3. We are poor in analyzing and forecasting based on sequences of data in time. We tend to assume linear extrapolation of trends. We cannot cope well with accelerating or decelerating changes.
7 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 7 4. We tend to see new situations as simply extensions of old, established situations, and therefore apply old, established actions, which may not be appropriate. 5. We tend to ignore the possibility that actions we take now may have unintended side-effects, and may cause problems that currently do not exist. 6. We make "ballistic" decisions, where we do not monitor the outcomes of those decisions after we have made them. 7. We only act if we feel competent to do so. Without some expectation of success, we are likely to not act at all. 8. We form simple hypotheses and limit the search for information in order to preserve our own selfperception of competence. 9. We, sometimes, pursue planning, information gathering and structuring processes that go on interminably as a defense against the possibility that we are incompetent. This may keep us from making contact with the reality that our actions are not working. 1. We, sometimes and for self-protection, only solve those problems that we know we can solve, despite the fact that those may not be the most important or pressing problems. 11. We are not particularly effective at recalling past information and events, which can lead to us to repeat past and inappropriate decisions. In more details, humans developed a tendency to deal with problems on an ad hoc basis (cf. P6): we fail because we tend to make a small mistake here, a small mistake there, and these mistakes add up (cf. p.7). He asserts that failure develops gradually according to its own logic. People court failure in predictable ways (cf. P.1) such as: 1. Acting without prior analysis of situations. 2. Failing to anticipate side effects and long-term repercussions. 3. Assuming the absence of immediately obvious negative effects means that the correct measures have been taken. 4. Being blinded to emerging needs and situational changes by over-involvement. Dorner distinguishes between good decisionmakers and poor decision-makers (cf p. 21). Good decision-makers have the following attributes: 1. They are more sensitive to subtle changes and act upon them more aggressively. 2. Their decisions take different aspects of the entire system into account, not just one aspect (cf. p.22). 3. They are more interested in the causal links behind events. 4. They often reflect on their own behaviors, make efforts to modify and structure them. He cites the following as contributing to the faulty logic of decision-makers: a) The tendency of a group of experts to reinforce one another s conviction that they are doing everything right (pp ). b) We must often make do with tentative solutions because time-pressure forces us to act before we can gather complete information or outline a comprehensive plan. (p. 4). c) Planners and decision makers may have no direct access, or indeed no access at all, to information about the situation they must address. (p. 4). He defines a system as a network of many variables in causal relationships to one another. (p. 73) He suggests that it is wise when correcting a deficiency to consider it within the context of its system and considering the system... means recognizing the different ways the variables can affect one another. Among the categories into which he groups such interrelationships are feedback (positive and negative), buffering, and critical versus indicator variables. He describes large bureaucratic organizations as well-buffered systems. The intricacies of their structures are well suited to negative feedback, and they are reflective of general goals that are widely shared. Thus, bureaucracies are well positioned to continue consuming resources even though they may be poorly structured to address the objectives underlying the generalized goals. Regarding the incompleteness of information needed to make a rational choice, he seems to implicitly propose resorting to record events, as they happen in time, which can be communicated/revisited to reduce uncertainty. He also emphasizes the need to deal with changes over time with prediction of how they may extend into the future, taking into account additional contingencies. He warns us of excessive planning and information gathering as they keep us from making contact with reality where we will not know whether or not our measures are working. Ultimately, he suggests, There is only one thing that does in fact matter, and that is the development of our common sense. (p. 198) Yet, in contradiction to that assertion, he reiterates: Temporal configurations often seem beyond common sense. we do not give adequate attention to the characteristics of processes that unroll over time. (cf. p. 198).
8 8 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 4. ARTIFICIAL INTELLIGENCE (AI) RESEARCH AND FAILURE Dorner seems to emphasize analysis and proper decision-making. The areas that closely capture the spirit of Dorner s suggestion in Artificial Intelligence (AI) are planning and reasoning about actions and changes. It is important to note that at least one area of research in AI, namely reasoning with incomplete information, is based on a notion that failure and progress was hampered by failure. A classical representation of an AI planning problem is as follows: an agent, in an initial situation/state, has available a set of actions where an action can be viewed as a partial function that transforms a state into another and it is only operative on a state if its preconditions (a set of conditions) are satisfied. A planning problem then becomes a search for a series of realistic actions that successively transform the initial state, S, into a goal state, S G. Given a state S, the change is driven by the performance of actions such as, e, to result in a new state, S 1, if, e, is operative on S. There is a need to formalize commonsense reasoning. The best that AI workers could provide, so far, is formalizing micro-worlds that represent limited domains of knowledge and reasoning (cf. ([Davis (1991), Genesereth and Nilsson (1987)). To check whether a plan has been successful, there is a need to check if the goal holds in the final state. This requires predictive reasoning: the ability to infer what may hold in later states that result from the performance of selected actions given the information about the initial/earlier states. In addition to issues such as incomplete information, multiple agents, and continuous change, some of the problems associated with the formalization of action and change that are of interest to AI are: The Frame Problem, The Qualification Problem and the Ramification Problem The Frame Problem The core of the frame problem is this: in any complex situation, there is a need to have to properly frame the problem in order to achieve a solution. This means identifying what is relevant and what is not, and determining the relevant information/knowledge needed to reach a solution. However, a proper framing of a problem requires a deep understanding of it. For AI, the frame problem is the formalization of inertial reasoning; inferring what does not change when performing an action. Unlike many technically interesting problems that emerged in AI, it has attracted the interest of philosophers (cf. Pylyshyn (1987), Ford and Pylyshyn (1996)). It is open-ended, and can depend on a wide variety of circumstances. The purely logical Frame Problem can be solved using monotonic logic by simply writing explicit axioms (which may be infinite) stating what does not change when an action is performed. The nonmonotonic solutions, which are based on failure, treat inertia as a default; changes are assumed to occur only if there is some special reason for them to occur. Absence of change is inferred when an action is performed unless a reason for the change can be found in the action axioms The Qualification Problem It arises generally in connection with the formalization of commonsense generalizations. Typically, these involve exceptions, which may iterate endlessly. In a sense, this problem is addressed somehow by the non-monotonic logic systems by allowing commonsense generalizations to be formulated as defaults: the initial generalization can be stated as an axiom and qualifications can be added incrementally in the form of further axioms. It is important to note that not every non-monotonic logic provides adequate mechanisms for qualification. Default logic, for instance, does not give the intuitively desired conclusions. Several aspects of the Qualification Problem remain challenging research problems in AI. For instance, no distinction is made between actions that cannot be attempted (probably because they are known to fail or unrealistic) and those that can be attempted, may fail. With the latter type of actions, those that may fail, we may need to reason about failure and its consequences. There is a need for a theory that can account for the ways in which actions (and plans that contain them) may fail The Ramification Problem It is essentially to formalize the indirect consequences of actions, where indirect effects, which are not delayed but are temporally immediate and causally derivative. It is closely related to the Frame Problem (cf. Thielscher (1989, 1996, 2) and Giunchiglia, Kartha and Lifschitz (1997)) The Need for Explicit Causal Information Hanks and McDermott (1987) showed that the existing systems of nonmonotonic logic (cf Reiter (198), McCarthy (982)) were unable to give the right solution to the Yale shooting problem. Indeed, this example and other simpler examples (cf. Pearl (1988), Lifschitz (199), Lin and Reiter (1994)) illustrated the need to include explicitly causal information in the input to defeasible reasoning. Our knowledge of a situation is usally partial. Causal relations are no exceptions. It is, thus, difficult to conclusively confirm whether or not two arbitrarily selected facts are causally related. It seems that we usually apply a principle like Occam's razor: we assume that two facts are not causally related unless we have strong positive evidence that suggests otherwise. Thus, we may use a defeasible implication, that may fail sometimes, to capture causal relations.
9 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 9 5. HUMAN INDUCED FAILURES Human beings seem to have the ability to solve complex problems. Such capability was more appreciated by the AI community when the attempt was, and still being made to capture such skills and expertise in automated intelligent systems. The key for human success seems to lie in their innate ability to intelligently perceive, learn and reorganize their strategies and problem-solving heuristics. Saying that, we are admitting that failure is at the essence of such a process and it is unavoidably necessary to prevent failure in similar (complex) situations, where using analogical reasoning could be beneficial. However, given a novel complex situation and sufficient time pressure, it would be, according to the frame problem, highly unlikely for a single human being to identify the relevant features in time. Such a statement is partly confirmed by Dorner s work. Looking at Dorner s logic without reference to, or justification as to why, humans behave as they do with regard to failure, we may conclude that some of the reasoning for failure are as follows: 1. Time pressure and process limitation may encourage us to act before we have clearly defined what the goal(s) is, or collected the required information. 2. Inappropriate modeling of complex systems. 3. Inability to identify new situations. 4. Underestimating the positive impact of an integrated monitoring and diagnostic system. 5. Underestimating the positive impact of recording past information, cases and events. 6. Underestimating the positive impact that learning could have on the reasoning process ability. 7. Inadequate use of a comprehensive theory of time and change to reason with. 8. Underestimating the frame, qualification and ramification problems. 9. Lack of culture and discipline leads to errorprone society. Decision-making should possess adequate information together with the knowledge and experience required for evaluation and comparison. If not, it engages in search for appropriate information and required knowledge to carry out the process. However, extensive search will slow down the whole process to the point where it could be pointless. In other words, appropriately stored (and indexed) information and experience will facilitate the process of decision-making. The expectation is that the outcome of the process is the best conclusion that can be reached based on the available information. However, there may be difficulties and obstacles, which they somehow correspond to the reasons cited above, in reaching the best conclusion, such as: a) Time pressure and/or the need to act before the required information, knowledge and experience are determined. b) Incompleteness, incorrectness and/or uncertainty of information to be acted upon. c) Limited reasoning ability to understand (complex) interactions between the different components of a system/situation and inability to make a proper manipulation and evaluation of information and/or the possible alternatives. d) Lack of experience: not monitoring events and keeping records of previous encountered situations.this corresponds to (4) and (5) mentioned above. e) Only react when conditions reach an alarming point: there is not much consideration of the health of the components and/or interactions between the different components unless abnormality is exhibited through the conditions being monitored. Avoiding failure in complex situations boils down to addressing those problems in the following way: Let DHF = Degree of Human Failure IK = Degree of Insufficiency of Knowledge (e.g., incompleteness, uncertainty, inaccuracy). TP = Time Pressure (e.g., in the sense that the issue has not been given adequate Consideration) LRA = Degree of the Limitation of Reasoning Ability. LE = Lack of Experience. TBI = Tardiness before Interference. HDF = IK*TP*LRA*LE*TBI 6. FAILURES IN PHYSICAL SYSTEMS Humans play an essential role in systems failure, which seem to fail for reasons that are quite compatible with those of systems. However, compared with systems and given time, they always have an alternative solution or view on the problem whereas a system may have choices limited by the encoded knowledge. Most operational systems are developed to realize a certain functionality. Thus, the approach can be roughly divided into the following phases: (1) Analysis where (functional and non-functional) requirements are determined; (2) Design whose outcome is an appropriate model that guarantees that the objectives of the system can be realized; and finally (3) the actual development where the model is materialized into the operational system. The approach is model-based; experiential knowledge regarding the system functionality and the interactions between the different components hardly comes into play.
10 1 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling Failure, in physical systems, is the responsibility of the systems developer/engineer whose role is to build systems, following an agreed specification that performs its intended functions throughout its operational life without fail. All systems, however, ultimately fail to perform its intended functions during its operational life at some stage. However, we may attempt to reduce the negative impact of failure and use it in a beneficial way as an opportunity for learning and understanding more about the system. The primary causes of failures in physical devices can be ascribed to: 1. Incorrect assumptions, due to the incompleteness of knowledge, with regard to system requirements. 2. Lack of knowledge of/about the function of the device being operated versus its design. The different components that constitute the system may not properly be integrated. 3. Faulty design/structure. Different components that constitute the system are not properly integrated to achieve its functionality. Control may not be appropriate. Encoded knowledge is incomplete, incorrect and/or inappropriate. 4. Incorrect operations/user error: Poor estimation of the effect of some behavior or maneuvering of the device. 5. Lack of knowledge about appropriate maintenance time and procedure. This may result in material deterioration/failures. 6. Inappropriate conditions/environment and poor fit between systems and its environment. Let DD = Design defect. IK = Degree of Insufficiency of Knowledge encoded in the system (e.g., incompleteness, uncertainty, inaccuracy). HF = Human Factor. Ig = Degree of Ignorance (e.g., in the sense that the issue has not been under consideration). W = Degree of Wear. DOF = Degree of Failure. DOF = DD*IK*HF*Ig*W. 7. REASONING WITH FAILURE The previous two sections show, nearly in full agreement with Dorner, that the causes of most failures whether it be human or physical can be traced back to: 1. Insufficiency of available knowledge (e.g., incompleteness, uncertainty, inaccuracy) and its proper management. 2. Time Pressure (e.g., in the sense that the issue has not given adequate consideration). 3. Natural wear and tear (aging). 4. Construction/design defects. 5. Technological/Manufacturing defects. 6. Defects due to improper use (poor maintenance). 7. Defects due to variations in the usage. 8. Limitations in reasoning ability. There is quite an abundant leterature that covers the above from various disciplines. However, little attention has been paid to the reasoning process and the possibility of its failure Towards Formalization of Practical Reasoning Processes Practical reasoning processes involve many aspects such as determining reasoning goals, drawing inferences, making assumptions and evaluating alternatives. Furthermore, observations and/or tests that validate assumptions, decisions such as which reasoning goal to pursue and/or which assumptions to make, are basic component of a reasoning process. However, it is important to note that representation, knowledge and reasoning are entangled. It is, thus, not a straightforward matter to draw the line clearly between a failure and its associated cause(s) due to: 1. Lack of knowledge and/or misunderstanding. 2. Misrepresentation an/or inappropriate, characterization. 3. Reasoning. It is quite reasonable to take the view that knowledge of a situation include: 1. Deep understanding and appropriate characterization: specifying its type, critical conditions that must be maintained etc. 2. Manipulative ability of desired actions together, with their preconditions and effects. 3. Meta reasoning and meta knowledge. 4. Competencies, which determine how well tasks are performed. One way of formalizing the reasoning process would be to specify at each step: The rule that has been employed. Its justification (.g., the knowledge that has been employed). Its direct effects (e.g., the knowledge that has been created, what formulae, rules, and/or decisions have been enabled/disabled by the application of the rule, and so on). A semantic account of the reasoning process can be given in terms of labeled transition systems. A transition system is a pair: T = <S, E>. Where: S - is a non-empty set of reasoning states, E - is a non-empty set of rules/events/actions (transitions) which act on S.
11 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 11 With every rule/event/action, e E, there is a transition, e, such that e (s) = t, if the event/action, e, can transform the state, s, into the state, t. In addition, a set S of initial states can be specified. Let AP be a fixed set of atomic propositions. Every state, s S, is assigned as a label the set of atomic propositions from AP that are true at s., i.e., L: S 2 AP L(s) = {A: A is true in S}. The idea is that the atomic propositions (or what is hidden in them) describe adequately a reasoning state, including the values of all important variables and conditions. Definition 7.1. A path (trace, history, execution),, in a transition system, T = <S, E>, is a sequence of states and events/actions which transform every state into its successor: = s e s 1 e1 e2 s 2... A path reflects a reasoning behavior regarding a goal Monitoring and Diagnosis of Reasoning Failure It seems difficult to draw clearly the line between failures that are due to lack of knowledge, inappropriate use of knowledge and reasoning failure. In the same way that a system, which has the ability to learn has an advantage over a similar system that does not have such abilities. Also, a system that is not capable of monitoring and adapting its reasoning processes may be disadvantaged. Reasoning failures may mistakenly be considered knowledge failure. Furthermore, the system may not be able to predict and/or handle changes in its processes and/or environment and thus, incapable of adapting its knowledge and/or its reasoning to deal with the new circumstances. In large and complex systems, there is a need to monitor the reasoning process and check its validity, and the validity of the consequences of decisions and to check their degree of conformity with what actually is expected. With the help of a diagnostic system and a meta-reasoning predictive ability of the reasoning process, we shall be able to determine whether a fault has occurred and how it could be corrected. To be able to successfully carry out the process of detecting reasoning failure, there is a need for a description, in one form or another, of the expected reasoning behavior of the system. For instance, if the reasoning process is described in terms of rules, there will be a need for expectations, which may vary in their degree of generality and scope, about the effect of applying these rules such as: If this reasoning rules is applied, the value(s) which is (are) produced will satisfy so and so conditions. A fault would then result from a mismatch between the expected behavior and the actual behavior. However, the system needs to identify which expectations are currently relevant to the reasoning process. It is important to make a clear distinction between expectation failures and reasoning failures. An expectation failure is usually caused by the occurrence of an event, which was not predicted by the system. It may be the result of a reasoning failure, if knowledge about the unexpected event occurrence was within the scope of the system s knowledge and the system could have planned for such an event. Once the system has detected an expectation failure, it must be able to determine what point in the reasoning process the detected failure was created. This task is quite difficult, because there is no guarantee that the system will detect every reasoning failure at the instant it occurs. 8. MONITORING, DIAGNOSIS AND LEARNING FROM FAILURES Most modern complex systems (such as AI systems) are increasingly knowledge-rich, dynamic and able to make decisions in complex and real-life environment. To be successful and to continue to be useful, these systems must be adaptable to the situations with which they have to deal, able to meta-reason about their reasoning processes, and to learn from their experiences. This is because, in addition to the complexity of the domains and the incompleteness of the knowledge encoded in these systems, it is not possible to predict the situations and many uncontrolled variables, which the system will have to deal with and the information required to deal with each of those situations. It seems difficult drawing clearly the line between failures that are due to lack of knowledge, inappropriate use of knowledge and reasoning failure. In the same way that a system, which has the ability to learn has an advantage over a similar system that does not have such abilities. Also, a system that is not capable of monitoring and adapting its reasoning processes may be disadvantaged. Reasoning failures may mistakenly be considered knowledge failure. Furthermore, the system may not be able to predict and/or handle changes in its processes and/or environment and thus, incapable of adapting its knowledge and/or its reasoning to deal with the new circumstances. Machine Learning (ML) systems (e.g., (Mitchell (1997)) are concerned with enhancing a system ability. However, they do not interfere with the reasoning processes, which are employed in manipulating a system s knowledge.
12 12 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling Obeid, Salah and Rao (26) suggests that an enterprise/large system needs to properly manage its knowledge in order to achieve successful management of its assets, react appropriately to external demands, cope with the need for change and decide when to initiate change. They propose that to be effective, Condition Monitoring, Diagnostics and Assessment (CM-D-A) should be integral components of the Knowledge Management (KM) activity in an ongoing adaptive learning process. In fact, it is not sufficient to detect, understand the reasons and how to recover from a failure. There is a need to employ meta-reasoning in order to learn from the failure and avoid future failures. It has been argued in Obeid and Rao (25) that there is a need for a finite-past temporal formalism to explain the cause of failure in a physical system, which may be due the occurrence of some unexpected event(s). It has also been proposed (cf. Obeid and Rao (22; 24; 25)) that reasoning with diagnostic temporal knowledge requires a formalism that: 1. employs an explicit representation of time and events; 2. embodies default rules; and 3. incorporates a domain description and the rules governing change to ensure that change to a state resulting from the successful occurrence of an event is minimal. Monitoring and diagnostic knowledge is temporal, incomplete and uncertain. An Integrated Condition Monitoring and Diagnosis (ICMD) system has to work with a model of the system being monitored where the notion of a modeling itself suggests incompleteness and uncertainty. Temporal uncertainty could be exhibited in different forms and in many contexts. In addition to time, events are associated with causes. An appropriate representation of events, have to go together with by a representation of changes in states, which can be captured by changes in the truth-values of fluents. The role of an integrated condition monitoring and diagnostic system is exactly to witness that a property fails to hold and to decide on an appropriate action in order to detect the root causes of such unpredictable and chaotic behavior. Condition Monitoring (CM) can be equated with run-time verification, requires the ability to reason about past states. However, there is a need to reason about the future states and all possible paths in order to be able to predict/plan the system s behavior, which require knowledge of the temporal properties that must hold. However, it is not sufficient to detect, understand the reasons and how to recover from a failure. There is a need to employ meta-reasoning in order to learn from the failure and avoid future failures. Improvement of reasoning processes can be achieved by continual monitoring and reevaluation of their performance via the comparison between the actual and expected consequences. The system can adapt to new circumstances by noticing how the old ways of solving problems are inadequate and thus adjust its reasoning and its view of the world. The laws of human reasoning should be closely related to the real situations as it is happening. The real systems are non-linear, non-stationary, multiinput and multi-output based, dynamic, fuzzy, chaotic and dynamic. As such, real situations are bound by imprecision and uncertainty and nontraditional methods of reasoning must be developed. Humans live in hope and reality. Like success failure is also a reality. As the complexity of human activity increase, uncertainties and poor-decision making confuses human mind, leading to chaos and failures of various degrees. A clear and intimate qualitative and quantitative relationship between human knowledge, set goal and intentions need to be established. This should tell us which course of positive actions to make in order to avoid failure at all costs. Humans are bestowed with innate meta reasoning and meta logic capability. Using this capability and by intelligently blending all the available tools, techniques and on-going developments (fuzzy logic, genetic algorithms, artificial neural networks, expert systems, pattern recognition, machine learning, hypertext, natural languages and high impact technologies), a robust and reliable solution could be found to minimise system s failures. 9. CONCLUSION In 1973, Dr. Lofti Zadeh stated that As the complexity of a system increases, our ability to make precise and yet significant statements about its behaviour diminishes until a threshold is reached beyond which precision and significance become almost mutually exclusive characteristics. We have, in this paper, explored some of the fundamental requirements needed for a Universal Theory of Failure Handling. We have shown that dealing with failure touches on our reasoning, predictive, evaluative and judgmental capabilities and thus it requires the ability to reason: 1. with incomplete and uncertain temporal information; 2. with events before they even happen; 3. about the effect of actions for as long as these are relevant and even if the available time does not permit; 4. about the reasoning process itself. We have discussed the notion of failure with respect to decision-making and knowledge. We have presented Dorner's logic of failure and research into artificial Intelligence and its implication for handling
13 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling 13 failures. We have proposed means of computing the degrees of failure induced by humans and in physical systems.. In addition, we have opened a healthy discussion on reasoning with failures and put forward a proposal for an integrative and proactive approach to monitoring, diagnosis and learning from failures. 1. REFERENCES 1. Davis, E., (1991), Reasoning Common Sense, San Francisco: Morgan Kaufmann. 2. Dorner D, (1997), The Logic of Failure: Recognizing and Avoiding Error in Complex Situations, HarperCollins Publishers. 3. Ford, K. M. and Pylyshyn, Z. (eds.), (1996), The Robot's Dilemma Revisited: The Frame Problem in Artificial Intelligence, Norwood, New Jersey: Ablex Publishing Co. 4. Genesereth, M. and Nilsson, J., (1987), Logical Foundations of Artificial Intelligence, San Mateo, California: Morgan Kaufmann. 5. Giunchiglia E., Kartha G. N. and Lifschitz V., (1997), Representing action: Indeterminacy and ramifications, Artificial Intelligence, Vol. 95, No. 2, Hare R. M., (1963), Freedom and Reason, Oxford University Press, Oxford. 7. Hanks S. and McDermott D., (1987), Nonmonotonic Logic and Temporal Projection, Artificial Intelligence, Vol. 33, Lifschitz V., (199), Frames in the space of situations, Artificial Intelligence, Vol. 46, Lin, F., and Reiter, R., (1994), State constraints revisited, Journal of Logic and Computation, Vol. 4, McCarthy J., (1982), Circumscription - A Form of Non-Monotonic Reasoning, Artificial Intelligence, Vol. 13, Mitchell T., (1997), Machine Learning, McGraw Hill. 12. Obeid N. and Rao, B.K.N.., (22), Innovative Trends in Knowledge Based Logical Reasoning in the Field of COMADEM, the Field, International Journal of Condition Monitoring and Diagnostic Engineering Management (COMADEM), Vol. 5, No. 3, 5-13, UK. 13. Obeid N. and Rao, B. K. N.., (24), Diagnostic Temporal Reasoning in Model-Based Diagnosis (MBD) of Dynamic System, International Journal of Condition Monitoring and Diagnostic Engineering Management (COMADEM), Vol. 7, No. 1, 13-28, UK. 14. Obeid N. and Rao, B. K. N. (25), Temporal Aspects in Condition Monitoring & Root Cause Failure Diagnosis of Modern Complex Systems, International Journal of Condition Monitoring and Diagnostic Engineering Management (COMADEM), Vol. 8, No. 3, UK. 15. Obeid N., Salah I. and Rao, B. K. N. (26), The Role of Knowledge Management in Diagnosing & Prognosing System s Failures. Diagnostyka, No.1 (37), 9 16, Poland. 16. Pearl J., (1988), Probabilistic Reasoning in Intelligent Systems: Networks of Plausible Inference, San Mateo, Calif.: Morgan Kaufmann. 17. Pylyshyn, Zenon (ed.), (1987), The Robot's Dilemma: The Frame Problem in Artificial Intelligence, Norwood, New Jersey: Ablex Publishing Co. 18. Rao, B.K.N. (26), Toward the Universal Theory of Failure, International Proceedngs of Condition Monitoring and Diagnostic Engineering Management (COMADEM), Published by Lulea University of Technology, Sweden. Pp Thielscher M., (1989), Ramification and causality, Artificial Intelligence, Vol. 89, No. 1-2, Thielscher M., (1996), Causality and the qualification problem, in KR'96: Principles of Knowledge Representation and Reasoning, Luigia Carlucci Aiello, Jon Doyle, and Stuart Shapiro, eds., San Francisco, California: Morgan Kaufmann, Thielscher M., (2), Representing the knowledge of a robot, in KR2: Principles of Knowledge Representation and Reasoning, Anthony G. Cohn, Fausto Giunchiglia, and Bart Selman, eds., San Francisco: Morgan Kaufmann, Reiter, R., (198), A logic for default reasoning, Artificial Intelligence, Vol. 13, Zadeh, L.A. (1973). The Concept of a Linguistic Variable and its Application to Approximate Reasoning, Memorandum ERL- M411, Berkeley, October. Professor Nadim OBEID holds a B.Sc in Mathematics (Lebanese University, 1979) and a B.Sc. in Business Administration (Lebanese University, 198). He also holds A Postgraduate Diploma (Essex University, 1982), M.Sc. in Computer Studies (Essex University, 1983) and a Ph.D in Computer Science (Essex University, 1987). In 1986, he joined the EUROTRA project as a Senior Research Officer and then in 1987, he took the post of a Lecturer in the department of Computer Science at Essex University. He took a leave of absence (without salary) from Essex University, in 1996, and became an associate Professor at Princess Sumaya University for Technology in Jordan where he was promoted in 22 to a professor. In 24, he joined, as a professor, King Abdullah II School for
14 14 DIAGNOSTYKA 1 (41)/27 OBEID, RAO, A Step Toward A Universal Theory Of Failure Handling Information Technology at the University of Jordan. The areas of research in which he is currently active are: Knowledge Representation, Multi-Agent Systems, Formalisation of Condition Monitoring and Diagnostic Reasoning, Knowledge Management and Logic of Universal Failure. He has been in the program committee of many international conferences. He has published around 2 publications in refereed international journals and more than 3 papers in edited books and refereed international conferences. He is the author of Winner of the Best Paper of the Year Award in the international journal of COMADEM (21-22). Professor Dr. Raj B. K. N. RAO PhD, DTech is internationally recognised and respected for pioneering the development of the holistic discipline of Condition Monitoring and Diagnostic Management (COMADEM). His distinguished academic career spans nearly 4 years of teaching, research and consultancy expertise in the fields of Environmental Engineering, Dynamics and Control and Human Factors in Engineering. He is the Director of COMADEM International and since 1988 he has successfully organised a series of COMADEM International events. He has published a number of refereed technical papers / books / journals / conference proceedings and has supervised and examined numerous doctoral research programmes. He is currently Visiting Professor at a number of Universities including the University of Glamorgan and Vellore Institute of Technology, India.
15 DIAGNOSTYKA 1 (41)/27 WYLE O, Reverse Engineering In Applications To Modal Analysis Of Virtual Models 15 REVERSE ENGINEERING IN APPLICATIONS TO MODAL ANALYSIS OF VIRTUAL MODELS Marek WYLE O Silesian University of Technology, Department of Fundamentals of Machinery Design Konarskiego 18a, 44-1 Gliwice, Poland, Summary The usage of a physical model as an input to design process is characteristic feature of inverse engineering. This approach is applied in such cases, when shape of a physical model was created inaccurately (in geometrical sense) using manual forming. Using the physical model is not possible to acquire complete knowledge about all the features of a final product (for example: modal values and its shapes). Therefore, surface of the physical model depends of quality of digitalization by 3D scanners. This shape is represented digitally as a cloud of points, depends usually triangularization. The obtained triangular mesh is a base for creation (using special programming tools): first - a surface model and next a solid (hybrid) model, too. We can define material features for this model. Because of that, we can use the solid model to perform modal analysis, using the finite element method. In this paper the author presents an example of creating a virtual model of rear-view mirror lining and its usage to modal analysis. Keywords: reverse engineering, virtual models, modal analysis. IN YNIERIA ODWROTNA W ZASTOSOWANIU DO ANALIZY MODALNEJ MODELI WIRTUALNYCH Streszczenie Cech charakterystyczn procesu konstruowania realizowanego zgodnie z zasadami in ynierii odwrotnej jest stosowanie modelu fizycznego, jako elementu wej ciowego do tego procesu. Podej cie takie stosuje si g ównie w przypadkach, gdy posta modelu fizycznego zostaje uzyskana w sposób przybli ony (w sensie geometrycznym), zwykle za pomoc r cznego kszta towania. Dysponuj c modelem fizycznym niemo liwe jest poznanie takich w asno ci przysz ego wytworu, jak np. parametry drganiowe (w szczególno ci cz sto ci w asne). Dlatego te modele takie poddaje si digitalizacji z u yciem skanerów 3D. Cyfrowa posta powierzchni modelu jest reprezentowana przez chmur punktów. Chmura punktów podlega zwykle procesowi triangularyzacji. Otrzymana siatka trójk tów jest podstaw do otrzymania (z u yciem specjalnego oprogramowania) modelu powierzchniowego, a nast pnie bry owego (hybrydowego). Dla modelu bry owego mo emy zdefiniowa cechy tworzywowe. A dzi ki temu, mo e by zastosowany do analizy cz stotliwo ciowej z u yciem metody elementów sko czonych. Artyku dotyczy przyk adu wykonania wirtualnego modelu obudowy lusterka wstecznego samochodu oraz wykonania jego analizy modalnej. S owa kluczowe: in ynieria odwrotna, modele wirtualne, analiza modalna. INTRODUCTION The usage of physical model as an input to design process [2] is a characteristic feature on inverse engineering. When we have a physical model for disposed, precise determination of a design shape of the final element or its part is difficult or even impossible to unequivocal geometric determination (usually because of manual forming). Moreover, it is also impossible to recognize its features, such as complete geometrical shape, mass, volume or dynamic features (for example modal values). Therefore, the surfaces of physical models are digitized [3, 5]. The result of digitalization process is a cloud of points, usually transformed into triangular mesh, mapping shape of model surface. On a base of such a digital record of the model surface it is possible to create a wireframe model, and next a surface model based on edges [7]. Finally, it is possible to create a solid model [6], using programming tools of CAx system. When we have the solid model we can define a sort of its material. When we dispossess precise definition of the geometrical shape and material features, we can use the finite element method to recognize for example modes of the virtual model. The sequence of models creation is presented in Fig. 1.
16 16 DIAGNOSTYKA 1 (41)/27 WYLE O, Reverse Engineering In Applications To Modal Analysis Of Virtual Models In the stage of modeling this knowledge (about geometric shape and material) is very useful and, for example allows, to modify geometric and material features of the model to ensure effective vibration isolation of the final product. In this paper the author presents an example of developing virtual model of a rear-view mirror lining (from the digitalization process of physical model, through wireframe, surface until solid model) and its usage to obtain the modal values (as a result of modal analysis using the Finite Element Method). Fig. 2. Shape of the physical model of the rear-view mirror lining non-virtual model mesh models (nonsurface models) CAD/CAE virtual geometric models Physical model Cloud of points Triangular mesh Wireframe 3D model Surface 3D model Solid 3D model 2. DIGITALIZATION OF PHYSICAL MODEL SURFACE Following the reverse engineering principles, the surface of the physical model was digitized. An optoelectronic 3D scanner [5] was used to carry out the operation. A cloud of points was the result of digitalization process (Fig. 3). This cloud of points was transformed into a triangle mesh, as a result of triangularization process. This process was aided by the Mesh3D [5] system, which system controls the 3D scanner performance. MES model Fig. 1. Sequence of models evolution 1. PHYSICAL MODEL OF A CAR REAR- VIEW MIRROR LINING The physical model of a rear-view mirror lining was made with ceramic material using manual forming techniques. Its external shape was inaccurate in geometrical sense; it only had an approximate character. The model shape maps only the external features of the surface. Whereas interior elements of the lining should be modelled during solid model stage. Fig. 3. A cloud of points as a digital model of the rear-view mirror lining 3. SURFACE AND SOLID VIRTUAL 3D MODELS The model obtained as a result of digitalization process provides an input element to make a wireframe 3D model. The following activities (to obtain wireframe and surface models) were made using tools of two modules of the CAD/CAM/CAE CATIA v5 r16 [1] system. They are: Digitizer Shaped Editor and Generative Shape Design. Making proper activities on triangular mesh of the model we obtained approximate splain curves, creating wireframe model (Fig. 4).
17 DIAGNOSTYKA 1 (41)/27 WYLE O, Reverse Engineering In Applications To Modal Analysis Of Virtual Models APPLICATION OF FINITE ELEMENT METHOD Fig. 4. Wireframe model of the rear-view mirror lining In the next step using existing edges the fragments of surface were created. This way the wireframe-surface model was obtained (Fig. 5). This model consists of continuous parametrical surfaces of the class continuity G2 [4]. The solid model was used as an input element to make modal analysis using the Finite Element Method. This Finite Element Method model and its analysis were made with the use of the Generative Structural Analysis module of CATIA v5 r16 system [1]. Digitization of the model shape was made using tetrahedral line element with maximal side length 2 mm (Fig. 7). As a result we obtained 7272 nodes and 2519 finite elements. The author assumpted, that the lining would be rigid fixed in a place of its attaching to car body (in Fig. 7 we can notice visible constraint symbols of nodes, received of freedom degrees Clamp Constrain ). Fig. 7. Shape of Finite Element Model (clamp joint and tetrahedron mesh are visible) Fig. 5. Surface model of the rear-view mirror lining The surface model mapped only the shape of exterior surface. Therefore using programming tools of the Part Design module [1] we obtained the solid model. This model was developed on constructional elements, situated in interior part of lining of mirror model (for example: strengthen ribs, Fig. 6). 5. OBTAINED RESULTS The author obtained as a result of compution the values of 1 first low-order modes. Their numerical values were presented on Image Edition window (Fig. 8). Together with numerical values the system delivers us qualitative information connected with parameters chosen by the user, for example shapes and values of deformations characteristic for own mode (Fig. 9). Fig. 6. Final solid model of the rear-view mirror lining (top and bottom views) Besides, this model has characteristic features of plastic material. These features are necessary to its application in the finite element method to make virtual modal analysis. Fig. 8. Numerical values of first ten low-order modes of the Finite Element Model
18 18 DIAGNOSTYKA 1 (41)/27 WYLE O, Reverse Engineering In Applications To Modal Analysis Of Virtual Models REFERENCES 1) 143,124 Hz 2) 163,27 Hz 3) 54,778 Hz 4) 665,13 Hz 5) 143,124 Hz 6) 143,124 Hz 7) 143,124 Hz 8) 143,124 Hz [1] CATIA v5 r16 Help Files [2] Dietrych J.: System and construction (in Polish), WNT, Warszawa, [3] Chlebus E.: CAx computer techniques in engineering of production (in Polish), WNT, Warszawa, 2. [4] Kiciak P.: Fundamentals of modeling curves and surfaces (in Polish), WNT, Warszawa, 2. [5] [6] Wyle o M.: Solid modelling in CATIA system. Examples and exercises (in Polish), HELION, Gliwice, 22. [7] Wyle o M.: CATIA. Fundamentals of surface and hybrid design (in Polish), HELION, Gliwice, 23. Marek WYLE O Assistant Professor at the Department of Fundamentals of Machinery Design, Silesian University of Technology at Gliwice. His research is focused on: CAD and CAM methods and techniques, reverse engineering and machinery designing. 9) 143,124 Hz 1) 143,124 Hz Fig. 9. Front views of first ten low-order mode shapes of the Finite Element Model (dark shape standard element, grey shape maximum displacement on each mode) 6. SUMMARY The research carried out so for allows formulating the following conclusions: Reverse engineering should be used always in such cases, when it is impossible to unequivocally determine the constructional shape of a final product in the initial stage of the design process. Virtual models created on the base of digitalization of physical models allow exact identifying geometric features of the object shape, but their surface shape is not identical to the physical model shape. The usage of virtual models in initial stage of the design process makes it possible to forecast (with high precision level) their dynamic features (for example: natural frequencies and corresponding mode shapes). This facilitates determination of proper vibration isolation of the product just in the design process stage.
19 DIAGNOSTYKA 1 (41)/27 KLIM, SZCZEPA SKI, BA AZI SKI, Causes And Effects Of Cascading Failures In Aircraft Systems 19 CAUSES AND EFFECTS OF CASCADING FAILURES IN AIRCRAFT SYSTEMS Zdzis aw H. KLIM *, Pawe SZCZEPA SKI **, Marek BA AZI SKI *** * Bombardier Aerospace, CA, 4 chemin de la Cote-Vertu Ouest, Montréal, (Québec) H4S 1Y9, Canada, ** Military University of Technology, Gen. S. Kaliskiego 2 St., -98 Warsaw 49, Poland, *** École Polytechnique of Montréal, C.P succ. «Centre-ville», Montréal, (Québec) H3C 3A7, Canada, Summary A cascading failure is a particular type of common-mode failure in which a single event, not necessarily hazardous in itself, can precipitate a series of other failures. The basic characteristic of a cascading failure is the propagation of an initial failure effect throughout the entire system or across and between the different systems. A domino effect is a principal characteristic of cascading failures when an initial event, which has little or no adverse effect on the aircraft, is transmitted downstream and ones of the subsequent failures generates hazardous effects. Cascading failures are considered low-probability high-consequence events. The prediction and analysis of cascading failures are complex due to their random dynamic involving continuous and switching operations that suddenly change the system s configuration. There are two methods that may be used for the purpose of this analysis: Event Tree Analysis (ETA) and Cause-Mode-Effect Analysis (CMEA). Keywords: safety analysis, cascading failures, risk assessment, reliability, aircraft. PRZYCZYNY I SKUTKI NIEZDATNO CI KASKADOWYCH W SYSTEMACH SAMOLOTU Streszczenie Niezdatno kaskadowa jest inicjowana przez pojedyncze (niekoniecznie niebezpieczne) zdarzenie, po którym nast puj inne tym razem ju niebezpieczne w skutkach zdarzenia. Cech charakterystyczn niezdatno ci kaskadowej jest jej propagacja z miejsca jej powstania na bli sze, a nast pnie na - dalsze i coraz to dalsze otoczenie. Efekt domina jest jej g ówn w a ciwo ci, gdzie skutek jakiego niepozornego zdarzenia przek ada si, dajmy na to, na katastrof lotnicz, kalectwo lub utrat ycia czy te jaki kataklizm ekologiczny. Niezdatno kaskadow postrzega si z jednej strony jako ma o prawdopodobn, z drugiej za jako bardzo dotkliw w swych konsekwencjach. Przewidywanie tych niezdatno ci jest niezwykle utrudnione z racji ich znacznej przypadkowo ci, dynamiki i zmian strukturalnych systemu. Analiz niezdatno ci kaskadowych przedstawiono z wykorzystaniem dwóch metod: Analizy Drzewa Niezdatno ci (ETA) oraz Analizy Przyczyn i Skutków (CMEA). S owa kluczowe: bezpiecze stwo, niezdatno ci kaskadowe, szacowanie ryzyka, niezawodno, samolot. 1. INTRODUCTION Some form of fail-safe design concept usually achieves the high levels of safety needed from essential aircraft systems, mainly through redundancy and isolation of systems, components and elements. However, this approach can be ineffective due to the possibility of common mode failure or cascading failures that may lead the aircraft into a hazardous situation with an unacceptable probability level. Of particular concern when assessing failure conditions are cascading failures. A cascading failure is a propagation of equipment outages, one propagating another [1]. A cascading failure is a particular type of common-mode failure in which a single event, not necessarily hazardous in itself, can precipitate a series of other failures. A cascading failure is not a single point failure or the occurrence of multiple concurrent failures but it is an event in which a component failure in the system/network will induce the failure of other components through normal system dynamics or behavior. A cascading failure scenario is one in which an initial failure leads to subsequent failures or increases the likelihood of subsequent failures due to direct effects, such as a failed part striking or burning another system element; or due to indirect effects, such as the initial failure increasing the loading on other system elements. Cascading failures are considered low-probability highconsequence events [2]. In multi-channel systems the channels usually share the total system loads, so that in the event of a failure of one channel, its load or part of it, will be
20 2 DIAGNOSTYKA 1 (41)/27 KLIM, SZCZEPA SKI, BA AZI SKI, Causes And Effects Of Cascading Failures In Aircraft Systems shared between the remaining healthy channels. This increase in load is likely to produce some increase in the failure rate of the remaining channels. This situation applies to electrical or hydraulic systems, data transfer network or mechanical systems, such as, for example, a flight control system in which two or three actuators share the total load. An increased failure rate of multi-channel systems resulting from additional loading can have a marked effect on the risk of combined failures [3]. The subsequent failure due to an increasing load could be instantaneous or may be delayed by some varying time period. Cascading studies can also be conducted to analyze vulnerability of the system to acts of sabotage [4], [5]. The classic cascading failure is characterized by a rapid propagation of failures. However, the cause-effect chain of events, leading ultimately to a hazardous situation, has to be considered, even if the failure propagation is spread over a large period of operation [6]. Moreover, the triggering event may be a permanent or a temporary fault. Therefore, an important attribute of a cascading failure that requires consideration in the analysis is the time factor. A cascading failure is a progression and generation of equipment outages, one precipitating another. The basic characteristic of a cascading failure is the propagation of an initial failure effect throughout the entire system or across and between the different systems. A domino effect is a principal characteristic of cascading failures when an initial event, which has little or no adverse effect on the aircraft, is transmitted downstream and ones of the subsequent failures generates hazardous effects. Given the kinds of large, interconnected applications that are increasingly deployed in modern, highly complex aircraft systems; the developers should consider the impact of cascading failures and mitigating strategies to address them. The systems that are exposed to cascading failures may have shared resources and/or shared messages, latencies or complex system human-machine interactions. The cascading failures can accelerate out of control, confounding human operators and denying them a chance for recovery. They may also neutralize redundancies, bypass firewalls or designed load paths, and exploit chance circumstances for which no designer could reasonably plan [7]. It is clear that these chains of contingencies are dependent on each other. In addition, several of them may cascade simultaneously. Consequently, the probability of these cascading failures occurring is much higher than the probability of a random (i.e. independent) tripping of k out of N components of the system. In considering likely failure sequences, one has to take account of the fact that following a series of failures the flight crew will be under increased stress and may be more likely to make mistakes. Therefore, the crew may contribute to cascading failure propagation by inserting an additional failure. 2. NATURE OF CASCADING FAILURES 2.1. Failure Identification The prediction of rare events, which are likely to produce cascading failures, is by definition, bound to be very difficult unless previous experience points out the way. However, there are various precautions and techniques, which can considerably reduce the chances of such multiple failures. The functional segregation of services and the physical separation of the components within the specific aircraft zone may prevent failure propagation or considerably decrease the probability of a cascading failure scenario. The containment of fragments of high-energy devices installed on aircraft in case of a failure and truly redundant (dissimilar) architecture of the system may preclude an initiating of the cascading failure chain. All these precautions and techniques, when correctly applied, result in the development of an in-depth defense strategy at the system and aircraft level against cascading failures. The defense strategy introduces several levels of protection, from a design and operations perspective, in order to preclude the domino effect of cascading failures before it reaches a safety critical point. The approach of minimizing the propagation of failure after the cascade has started is complementary to the usual approach of minimizing the risk of the first few cascading failures [8] Characteristic of cascading failures The nature of cascading failures may vary considerably and it is difficult to provide a common definition or characteristic of such an event that would apply to all possible scenarios. The following list of failure events presents various manifestations generated by cascading failures and highlights the insidiousness of this type of failure. 1. The ejection in flight of the cargo door resulted in the sudden depressurization, which subsequently led to the disruption of the floor structure causing a few passengers and parts of the aircraft to be ejected, rendering one engine inoperative and impairing the flight controls (tails surfaces) so that it would be impossible for the crew to regain control of the aircraft. This sequence of events finally leads to a catastrophe. First failure: ejection of cargo door due to incorrect door latching Cascading: between different systems 2. One tire blew out/failed during take-off following by a second tire blew-out. Subsequently, the wheels and brakes assemblies started rubbing the runway surface generating excessive heat. Crew decided for rejected takeoff and was using the remaining brakes to stop
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|Reviews for A Song of Manes and Antlers
| iluvaqt chapter 33 . 10/13
I was very happy to read that Carella is Roland's full blood sister. And that most of the Lannister family love her and are protective of her. It does cause you to wonder if Robert had treated then equally if Joffery would have loved his brother instead of being jealous and threatened by him. His cruel and selfish steak is genetic though. His mother has it in her.
| Guest chapter 27 . 10/10
I find your fighting scenes drag on a bit too much and I ended up skipping to the ends of the battle just to get on with it. I'd suggest making them not quite so long
| CrystalVixen93 chapter 33 . 10/10
Love your story and can't wait to see what happens next so I hope you update again soon plz
| Fiction Affliction chapter 33 . 10/9
It was really good! But, the grammatical errors kept nagging at me, take it from me, proofing your story does wonders.
| explodingbunnies52 chapter 33 . 10/9
Nice work!
| Darkcush chapter 4 . 10/9
Absolutely massive dog lol.
Great chapter tho.
| Hektols chapter 33 . 10/9
I don't think that the Greyjoys will join the Lannister forces, at least not while Balon is in charge.
It will be great if Tyrion finds out about Baelish business in his new charge.
Good work with the double meaning about Joffrey's crossbow, specially when interacting with Margaery. I wonder if he will enforce that idea to hunt and punish homosexuals, specially if he tries to apply with Loras.
| Master of Dragons God chapter 33 . 10/9
Nice Chapter
| Silver crow chapter 33 . 10/9
Okay starting off the only bad thing I've got to say about this chapter is you got a few names mispelled but it didn't ruin everything
Despite the fact we didn't get any Roland this was a pretty good chapter from the point of view of the king shit himself and the sea rats
Thought I am wondering how quickly will the Tyrells notice what a huge fuck up they've made by joining Joffrey and how they are going to appease Roland so they still have a place in his Kingdom because while arguably beside the royal family they are the most powerful house thanks to the land they govern thought in all fairness the power of the reach depends on how good the weather is if you ask me but as I was saying they also have a lot of powerful banner men such as the Hightowers, Rowans, Tarlys and Redwynes who all have a small claim on their castle which Roland can give to them if the Tyrells aren't on his side when the dust settles
As for the Lannisters trying to allie with the Greyjoys I hope you have that attempt to be a futile one because Balon Greyjoy is a stubborn miserable old shit who wouldn't Allie with the "crown" because unless the Lannisters invade the islands and destroy the iron fleet he won't bend the knee to them and then if he does the iron born would be useless allies as they've got nothing
Another thing is I don't think Balon would ever give up his crown to serve the Lannisters regardless of how much Roland has humiliated him because I don't think the iron born would ever obey the King who kneel twice and the Lannisters can't get an alliance with them by promising them independence because if they do that then all the other high lords will demand the same thing because if the iron born can get it why not them
Also I'm suprised that Asha isn't already thinking that the iron born war is fucked and her best chance of gaining power over the Isles ahead of Theon and his uncles is to take her supporters and join Roland as long as he names her Lady Paramount of the Iron isles on the condition she continues the work of her grandfather by making the Iron born into traders and maybe explores so basically not the scum of Westros also I'm suprised again that Theon isn't thinking the same thing thought I guess he'd be lucky is Roland didn't hand him over to the Starks thinking about it that could be a twisted way for Asha to show her loyalty to Roland by handing her brother over to them
As for there plan for Barrowtown eh I don't see it going well I mean yeah Theons good at sieging castles in the North thanks to Ned dragging him to everyone of them at some point when he was a ward but unlike Winterfell or the Dread for the doesn't know the intimate details of Barrowtown but even if they do take the town I see the iron born sustaining heavy loses
Now the last thing I'm curious about is what are you going to do with Dany are you going to make her see that Roland is what's best for westros seeing as how he knows the place or are you going to make her the insane self righteous Dany who thinks she knows best for Westros despite the fact she's never actually been to westros proper
Anyway hope you update soon
| Laura201112 chapter 33 . 10/9
wonderdful job
| birdy chapter 33 . 10/8
please update as soon as you can this was a great chapter please update as soon as you can
| HoosierCullen chapter 33 . 10/8
A chapter filled with fools that are the opposition to Roland. Should be interesting to see if their plans will come to fruition or if they will fail miserably. I do hope that you have Littlefinger failing miserably as well with his plots in using the Vale as his puppet army. I think that Roland would make good on keeping that happening. Should be interesting indeed.
| sketchywolf chapter 33 . 10/8
| Guest chapter 33 . 10/8
great story
| GLCW2 chapter 33 . 10/8
Wow, you really should at least read over your chapters before posting. There are a lot of errors. That being said, I can't wait to see what Roland will do next.


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Pregnant. Movement of the fetal has stopped. Why has it stopped? What to do if it moves?
this is my 8 month of pregnancy. since last 5 days the fetal movement has reduced. previously the movement was very frequent and noticeable but now the movement is very lean n weak. i wonder whether this is normal or there is something to worry about and if there is any problem what should i do so that the baby starts moving as previous
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Dr. Richa Agarwal
Thanks for your query.
You should consult a gynecologist immediately because this is an emergency, because your
fetal movement
is decreased.She will do your
to rule out the cause.
There are many reasons for decreased fetal movement so in my opinion better you go and consult your doctor.
Good luck.
Take care.
Answered: Wed, 15 May 2013
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Thanks for your query.
You should consult a gynecologist immediately because this is an emergency, because your fetal movement is decreased.She will do your ultrasonography to rule out the cause.
There are many reasons for decreased fetal movement so in my opinion better you go and consult your doctor.
Good luck.
Take care.
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Mic pro lost recording
I record a conversation with mic pro and to save it I sent it to my e mail. Now I lost this recording from my I pad and I can,t see it on my email because it says expired.
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Please I need help
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SCORPIO October 24th - November 22nd
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Ten reasons why we want to be on TOWIE!
Russell Grant's Daily Horoscopes for Monday 4th January 2016: Scorpio
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