No / Quality assessment (QA) requires high levels of domain-specific experience and knowledge. QA tasks for toxicological data are usually performed by human experts manually, although a number of quality evaluation schemes have been proposed in the literature. For instance, the most widely utilised Klimisch scheme1 defines four data quality categories in order to tag data instances with respect to their qualities; ToxRTool2 is an extension of the Klimisch approach aiming to increase the transparency and harmonisation of the approach. Note that the processes of QA in many other areas have been automatised by employing expert systems. Briefly, an expert system is a computer program that uses a knowledge base built upon human expertise, and an inference engine that mimics the reasoning processes of human experts to infer new statements from incoming data. In particular, expert systems have been extended to deal with the uncertainty of information by representing uncertain information (such as linguistic terms) as fuzzy sets under the framework of fuzzy set theory and performing inferences upon fuzzy sets according to fuzzy arithmetic. This paper presents an experimental fuzzy expert system for toxicological data QA which is developed on the basis of the Klimisch approach and the ToxRTool in an effort to illustrate the power of expert systems to toxicologists, and to examine if fuzzy expert systems are a viable solution for QA of toxicological data. Such direction still faces great difficulties due to the well-known common challenge of toxicological data QA that "five toxicologists may have six opinions". In the meantime, this challenge may offer an opportunity for expert systems because the construction and refinement of the knowledge base could be a converging process of different opinions which is of significant importance for regulatory policy making under the regulation of REACH, though a consensus may never be reached. Also, in order to facilitate the implementation of Weight of Evidence approaches and in silico modelling proposed by REACH, there is a higher appeal of numerical quality values than nominal (categorical) ones, where the proposed fuzzy expert system could help. Most importantly, the deriving processes of quality values generated in this way are fully transparent, and thus comprehensible, for final users, which is another vital point for policy making specified in REACH. Case studies have been conducted and this report not only shows the promise of the approach, but also demonstrates the difficulties of the approach and thus indicates areas for future development. / U 7th Framework Programme Integrated Project “Integrated In Silico Models for Prediction of Human Repeated Dose Toxicity of Cosmetics to Optimise Safety” (COSMOS). Grant Number: 266835. Cosmetics Europe.

Syftet med denna avhandling var att uppskatta livslängden och tillförlitligheten för det elektromekaniska linjära ställdonet genom att använda metoder för sannolikhet och statistik, med fokus på att fastställa svagare områden som kan förbättras för att inkludera dessa förbättringar i kommande generation. Bedömningen gjordes kvantitativt och kvalitativt. FMEA valdes för den kvalitativa analysen. För den kvantitativa analysen bedömdes Weibull-distribution vara den mest lämpliga för att skatta komponenternas felfrekvens. För detta valdes form- och skalparametrar enligt B. Bertsche. [1] Övergripande systemtillförlitlighet uppskattades utifrån den Boolean-teorin, där en känslighetsanalys utfördes med utgång från systemet fortsatta funktion. Det inkluderade utvärdering av komponenternas relativa betydelse för den övergripande tillförlitligheten, och att utföra känslighetsanalys med avseende på systemkomponenternas fördelningsparametrar. Baserat på den information som erhållits från kvalitativ och kvantitativ analys, erhölls underhållsaktiviteter för det elektromekaniska ställdonet under servicetiden. För att föreslå lämpliga tillförlitlighetstester var det nödvändigt att först fastställa storlek och testlängd för kommande prov. Flera testmetoder och respektive provstorleksuppskattning och urvalstester för testlängd studerades. Resultatet från FMEA ser totalt sett lovande ut. Det finns en möjlighet att några mindre fel uppstår i smörj-, kyl- och övervakningssystemet, som kan tas om hand genom att följa föreslagna underhållsaktiviteter. Ingen komponent sticker särskilt ut i tillförlitlighetsanalysen, med tanke på att säkerhetsfaktorerna för växlar överskrider minimigränsen och axlar som är konstruerade för oändlig livslängd. Individuellt verkar de utvalda lagren inte påverka det övergripande systemets tillförlitlighet. Men eftersom komponenterna anses vara i serie verkar den kombinerade tillförlitligheten hos lagren dominera hela systemets tillförlitlighet. Eftersom de tre fallstudierna genomförs för att förstå systemets beteende när det gäller tillförlitlighet, gäller ovanstående resultat för de två första fallstudierna där redskapen var säkra. I fallstudie tre påverkades systemets tillförlitlighet av både växlar och lager. Känslighetsanalysen följde samma mönster som det ses i tillförlitlighetsanalys. För fallstudie 1 och 2 - lager är signifikanta och i fallstudie 3 - rack och kugghjul 2 var mer signifikanta än lager. För tillförlitlighetsprovning har censureringsmetoder av Typ 1 och Typ 2 visat sig vara lämpliga. För uppskattning av testprov erhölls att generaliseringen av felmetoden med hjälp av Larsens nomogram var idealisk för tidiga förutsägelser. / The purpose of this thesis was to estimate the life and reliability of an electromechanical linear actuator by using methods of probability and statistics. It was essential to determine weaker areas subject to improvement and include these improvements in the design to next generations. The assessment was carried out quantitatively and qualitatively. Failure mode effects analysis was the method opted for the qualitative analysis. For the quantitative analysis, Weibull distribution was found to be the most suitable to present the failure rate of components. For the same, the shape and scale parameters were selected as suggested by B. Bertsche. [1] Overall system reliability was estimated on the basis of Boolean theory. Sensitivity analysis was carried out by using survival signature method. It included evaluating the relative importance of the components with respect to overall reliability and carrying out sensitivity analysis with respect to the distribution parameters of the system components. Based on the information obtained from qualitative and quantitative analysis, maintenance activities were derived for the electro-mechanical actuator for the period of service time. To suggest the suitable reliability tests, it was necessary to first determine the test sample size and test duration. Several test methods and respective sample size estimation and test duration selection methods were studied. In performed failure mode and effects analysis, overall the system looks promising. There is a possibility of some minor possible failures to occur in lubrication, cooling and monitoring system, which could be taken care of by following suggested maintenance activities. No component in particular stand out in the reliability analysis, given that the safety factors of gears exceed the minimum limit and shafts designed for infinite lifetime. Individually the selected bearings seem to not affect the overall system’s reliability. However, since the components are considered to be in series, the combined reliability of the bearings seem to dominate the whole system’s reliability. As the three case studies are conducted to understand the system’s behaviour in terms of reliability, above result is applicable for the first two case studies where gears are found to be safe. In case of case study three, the system’s reliability is found to be affected by both gears and bearings. The results of sensitivity analysis followed the same pattern as reliability analysis. For case study 1 and 2 - bearings were significant and in case of case study 3 - rack and gear 2 were more significant than bearings. For reliability testing, Type 1 and Type 2 censoring methods both are found to be suitable. For test sample estimation, generalisation of failures method using Larsen’s nomogram was found ideal for early predictions.

Structural Reliability treats uncertainties in structural design systematically, evaluating the levels of safety and serviceability of structures. During the past decades, it has been established as a valuable design tool for the description of the performance of structures, and lately stands as a basis in the background of the most of the modern design standards, aiming to achieve a uniform behaviour within a class of structures. Several methods have been proposed for the estimation of structural reliability, both deterministic (FORM and SORM) and stochastic (Monte Carlo Simulation etc) in nature. Offshore structures should resist complicated and, in most cases, combined environmental phenomena of greatly uncertain magnitude (eg. wind, wave, current, operational loads etc). Failure mechanisms of structural systems and components are expressed through limit state functions, which distinguish a failure and a safe region of operation. For a jacket offshore structure, which comprises of multiple tubular members interconnected in a three dimensional truss configuration, the limit state function should link the actual load or load combination acting on it locally, to the response of each structural member. Cont/d.

The presented doctoral thesis is focused on assessment of human factor impact on safety of industrial furnaces. Industrial furnaces are classified as machinery and belong to a group of industrial thermal equipment. The operation of industrial furnaces is burdened with the risks which the manufacturers and the furnace operators realize. The first part of the thesis presents an analysis of the current situation of legislation and scientific knowledges in the field of assessment of human factor impact on safety of industrial furnaces. In this part of the thesis the issue of human factor in other industrial branches: chemical industry, aviation and nuclear industry is also described. On the basis of conducted research the main aim of the thesis was established: preparation of a methodology for assessment of human factor impact on safety of industrial furnaces. Secondary targets were also listed. The second part deals with the assessment of risks connected with the operation of industrial furnaces and the assessment of human factor impact on safety of industrial furnaces. The furnace safety requirements, the process of furnaces risk assessment, the methods used for risk assessment and problems connected with the risk assessment are described. This part of the thesis explains the concept of human factor, presents a classification and description of the methods used for human reliability assessment, as well as the factors influencing the reliability of the operator. The third part of the thesis contains a proposed methodology for assessment of human factor impact on safety of industrial furnaces. Within the methodology performance shaping factors are stated, qualitative and quantitative assessment of human factor impact on safety of industrial furnaces is made and the system integration of the knowledges into the developed methodology is proposed – qualitative model for improvement of system state. The methodology is further verified on a real equipment – a hardening furnace.

The object of this diploma thesis is to perform Functional Hazard Assessment of small four-seat aircraft according to Federal Aviation Regulations Part 23, which would be similar to present aircrafts on market. Input data were acquired by research of systems aircrafts use on current market. On this basis the Functional Hazard Assessment was performed ad aircraft level. Total loss of power supply was qualified as Catastrophic therefore is used in following assessment. A preliminary failure rate assessment of typical parts used in electrical system was performed at the end of diploma thesis. For the most crucial parts a simple model was created and failure rate computed.

This thesis presents a method for reliability assessment of a power grid with distributed generation providing support to the system. The distributed generation units considered for this assessment are Combined Heat and Power (CHP) units operated by individual customers at their site. CHP refers to the simultaneous generation of useful electric and thermal energy. CHP systems have received more attention recently due to their high overall efficiency combined with decrease in costs and increase in reliability. A composite system adequacy assessment, which includes the two main components of the power grid viz., Generation and Distribution, is done using Monte Carlo simulation. The State Duration Sampling approach is used to obtain the operating history of the generation and the distribution system components from which the reliability indices are calculated. The basic data and the topology used in the analysis are based on the Institution of Electrical and Electronics Engineers - Reliability Test System (IEEE-RTS) and distribution system for bus 2 of the IEEE-Reliability Busbar Test System (IEEE-RBTS). The reliability index Loss of Energy Expectation (LOEE) is used to assess the overall system reliability and the index Average Energy Not Supplied (AENS) is used to assess the individual customer reliability. CHP reliability information was obtained from actual data for systems operating in New England and New York. The significance of the results obtained is discussed.

Multi-Criteria Decision Making (MCDM) problems are often associated with tradeoffs between performances of the available alternative solutions under decision making criteria. These problems become more complex when performances are associated with uncertainty. This study proposes a stochastic MCDM procedure that can handle uncertainty in MCDM problems. The proposed method coverts a stochastic MCDM problem into many deterministic ones through a Monte-Carlo (MC) selection. Each deterministic problem is then solved using a range of MCDM methods and the ranking order of the alternatives is established for each deterministic MCDM. The final ranking of the alternatives can be determined based on winning probabilities and ranking distribution of the alternatives. Ranking probability distributions can help the decision-maker understand the risk associated with the overall ranking of the options. Therefore, the final selection of the best alternative can be affected by the risk tolerance of the decisionmakers. A Group Decision Support System (GDSS) is developed here with a user-friendly interface to facilitate the application of the proposed MC-MCDM approach in real-world multiparticipant decision making for an average user. The GDSS uses a range of decision making methods to increase the robustness of the decision analysis outputs and to help understand the sensitivity of the results to level of cooperation among the decision-makers. The decision analysis methods included in the GDSS are: 1) conventional MCDM methods (Maximin, Lexicographic, TOPSIS, SAW and Dominance), appropriate when there is a high cooperation level among the decision-makers; 2) social choice rules or voting methods (Condorcet Choice, Borda scoring, Plurality, Anti-Plurality, Median Voting, Hare System of voting, Majoritarian iii Compromise ,and Condorcet Practical), appropriate for cases with medium cooperation level among the decision-makers; and 3) Fallback Bargaining methods (Unanimity, Q-Approval and Fallback Bargaining with Impasse), appropriate for cases with non-cooperative decision-makers. To underline the utility of the proposed method and the developed GDSS in providing valuable insights into real-world hydro-environmental group decision making, the GDSS is applied to a benchmark example, namely the California‘s Sacramento-San Joaquin Delta decision making problem. The implications of GDSS‘ outputs (winning probabilities and ranking distributions) are discussed. Findings are compared with those of previous studies, which used other methods to solve this problem, to highlight the sensitivity of the results to the choice of decision analysis methods and/or different cooperation levels among the decision-makers

No description available.

Research in the field of reliability based design is mainly focused on two sub-areas: The computation of the probability of failure and its integration in the reliability based design optimization (RBDO) loop. Four papers are presented in this work, representing a contribution to both sub-areas. In the first paper, a new Second Order Reliability Method (SORM) is presented. As opposed to the most commonly used SORMs, the presented approach is not limited to hyper-parabolic approximation of the performance function at the Most Probable Point (MPP) of failure. Instead, a full quadratic fit is used leading to a better approximation of the real performance function and therefore more accurate values of the probability of failure. The second paper focuses on the integration of the expression for the probability of failure for general quadratic function, presented in the first paper, in RBDO. One important feature of the proposed approach is that it does not involve locating the MPP. In the third paper, the expressions for the probability of failure based on general quadratic limit-state functions presented in the first paper are applied for the special case of a hyper-parabola. The expression is reformulated and simplified so that the probability of failure is only a function of three statistical measures: the Cornell reliability index, the skewness and the kurtosis of the hyper-parabola. These statistical measures are functions of the First-Order Reliability Index and the curvatures at the MPP. In the last paper, an approximate and efficient reliability method is proposed. Focus is on computational efficiency as well as intuitiveness for practicing engineers, especially regarding probabilistic fatigue problems where volume methods are used. The number of function evaluations to compute the probability of failure of the design under different types of uncertainties is a priori known to be 3n+2 in the proposed method, where n is the number of stochastic design variables. / <p>QC 20160317</p>

Structural Reliability treats uncertainties in structural design systematically, evaluating the levels of safety and serviceability of structures. During the past decades, it has been established as a valuable design tool for the description of the performance of structures, and lately stands as a basis in the background of the most of the modern design standards, aiming to achieve a uniform behaviour within a class of structures. Several methods have been proposed for the estimation of structural reliability, both deterministic (FORM and SORM) and stochastic (Monte Carlo Simulation etc) in nature. Offshore structures should resist complicated and, in most cases, combined environmental phenomena of greatly uncertain magnitude (eg. wind, wave, current, operational loads etc). Failure mechanisms of structural systems and components are expressed through limit state functions, which distinguish a failure and a safe region of operation. For a jacket offshore structure, which comprises of multiple tubular members interconnected in a three dimensional truss configuration, the limit state function should link the actual load or load combination acting on it locally, to the response of each structural member. Cont/d.