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Dissertations / Theses on the topic 'Control reliability'
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Steel, Donald. "Software reliability prediction." Thesis, Abertay University, 1990. https://rke.abertay.ac.uk/en/studentTheses/4613ff72-9650-4fa1-95d1-1a9b7b772ee4.
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The aim of the work described in this thesis was to improve NCR's decision making process for progressing software products through the development cycle. The first chapter briefly describes the software development process at NCR, detailing documentation review and software testing techniques. The objectives and reasons for investigating software reliability models as a tool in the decision making process are outlined. There follows a short review of software reliability models, with the Littlewood and Verrall Bayesian model considered in detail. The difficulties in using this model to obtain estimates for model parameters and time to next failure are described. These estimation difficulties exist using the model on good datasets, in this case simulated failure data, and the difficulties are compounded when used with real failure data. The problems of collecting and recording failure data are outlined, highlighting the inadequacies of these collected data, and real failure data are analysed. Software reliability models are used in an attempt to quantify the reliability of real software products. The thesis concludes by summarising the problems encountered when using reliability models to measure software products and suggests future research into metrics that are required in this area of software engineering.
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Wickstrom, Larry E. "Reliability of Electronics." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700024/.
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The purpose of this research is not to research new technology but how to improve existing technology and understand how the manufacturing process works. Reliability Engineering fall under the category of Quality Control and uses predictions through statistical measurements and life testing to figure out if a specific manufacturing technique will meet customer satisfaction. The research also answers choice of materials and choice of manufacturing process to provide a device that will not only meet but exceed customer demand. Reliability Engineering is one of the final testing phases of any new product development or redesign.
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Shi, Yuan Feng. "Reliability-based semi-active control using MR damper." Thesis, University of Macau, 2004. http://umaclib3.umac.mo/record=b1445126.
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Olsen, James Jonathan. "Control and reliability of optical networks in multiprocessors." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/37180.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.Includes bibliographical references (leaves 138-142).
by James Jonathan Olsen.
Ph.D.
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Olteanu, Denisa Anca. "Cumulative Sum Control Charts for Censored Reliability Data." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26665.
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Companies routinely perform life tests for their products. Typically, these tests involve running a set of products until the units fail. Most often, the data are censored according to different censoring schemes, depending on the particulars of the test. On occasion, tests are stopped at a predetermined time and the units that are yet to fail are suspended. In other instances, the data are collected through periodic inspection and only upper and lower bounds on the lifetimes are recorded. Reliability professionals use a number of non-normal distributions to model the resulting lifetime data with the Weibull distribution being the most frequently used. If one is interested in monitoring the quality and reliability characteristics of such processes, one needs to account for the challenges imposed by the nature of the data. We propose likelihood ratio based cumulative sum (CUSUM) control charts for censored lifetime data with non-normal distributions. We illustrate the development and implementation of the charts, and we evaluate their properties through simulation studies. We address the problem of interval censoring, and we construct a CUSUM chart for censored ordered categorical data, which we illustrate by a case study at Becton Dickinson (BD). We also address the problem of monitoring both of the parameters of the Weibull distribution for processes with right-censored data.Ph. D.
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KALEEM, ULLAH MUHAMMAD. "INVENTORY CONTROL SYSTEM : Optimization of production system and reliability." Thesis, Högskolan Dalarna, Datateknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4781.
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The main idea of this research to solve the problem of inventory management for the paper industry SPM PVT limited. The aim of this research was to find a methodology by which the inventory of raw material could be kept at minimum level by means of buffer stock level.The main objective then lies in finding the minimum level of buffer stock according to daily consumption of raw material, finding the Economic Order Quantity (EOQ) reorders point and how much order will be placed in a year to control the shortage of raw material.In this project, we discuss continuous review model (Deterministic EOQ models) that includes the probabilistic demand directly in the formulation. According to the formula, we see the reorder point and the order up to model. The problem was tackled mathematically as well as simulation modeling was used where mathematically tractable solution was not possible.The simulation modeling was done by Awesim software for developing the simulation network. This simulation network has the ability to predict the buffer stock level based on variable consumption of raw material and lead-time. The data collection for this simulation network is taken from the industrial engineering personnel and the departmental studies of the concerned factory. At the end, we find the optimum level of order quantity, reorder point and order days.
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Meyer, Tobias [Verfasser]. "Optimization-based reliability control of mechatronic systems / Tobias Meyer." Paderborn : Universitätsbibliothek, 2016. http://d-nb.info/1124894802/34.
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Yang, Luo. "RELIABILITY-BASED DESIGN AND QUALITY CONTROL OF DRIVEN PILES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153755606.
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Wikman, Thomas Stig. "Reflex control for robot system preservation, reliability, and autonomy." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057936323.
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Raghu, Anand. "Prediction of workpiece location as a function of fixture-induced errors." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/18840.
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Kumbale, Murali. "Bulk transmission system reliability analysis of protection and control groups." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13840.
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Robinson, David Charles. "Computer based on-line quality control." Thesis, University of Portsmouth, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292316.
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Orsten, Andreas. "Automatic Reliability-based Control of Iceberg Towing in Open Waters." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26349.
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Icebergs pose serious threats to existing and planned offshore structures, vessels, and operations in Arctic waters. In order to eliminate the threat, iceberg handling must be performed. This is typically done by single vessel towing of the iceberg, using a floating towline laid encircling the iceberg in the waterline. Common challenges during towing of icebergs are towline rupture, that the towline slips off the iceberg, or that the iceberg overturns. These are denoted failure modes of iceberg towing operations. Motivated by finding a way to safely alter the iceberg trajectory such that it no longer poses a threat, this thesis discusses automatic reliability-based control of iceberg towing in open waters.A mathematical model for single vessel iceberg towing in the presence of a constant and irrotational ocean current is developed. A reliability index is defined for each failure mode of the towline. The index is based on towline tension measurements and maximum tension limits for the failure mode, for instance the towline rupture tension limit.A line-of-sight guidance and control method is developed in order to tow an iceberg to and along a pre-defined straight-line path in the presence of an ocean current, using a towing vessel and a towline. The method assumes that the iceberg position is measured, and calculates a desired iceberg course angle. Using a reference model and backstepping controller, the towing vessel is positioned in order to apply a tow force in the desired iceberg course direction.Two reliability index-based penalty control schemes are proposed. The first penalizes the commanded thrust when the reliability index is too close to the lower limit. The second penalizes the velocity reference for the tow operation. A limitation to the rate of change of the penalty is proposed for reducing how fast the penalty decreases, in order to achieve a steady velocity reference.The mathematical model and control methods are tested, both in simulations, and experimentally in the Marine Cybernetics Laboratory (MC Lab) at the Norwegian University of Science and Technology (NTNU). Simulations and experiments show that it is advisable to avoid transients in the towline tension, and that the penalty on commanded thrust is not sufficiently effective. Using the line-of-sight method, simulations and experiments show that the vessel tows the iceberg to and along the desired path. A combination of the line-of-sight method and the velocity reference penalty scheme is simulated, and shown to safely tow the iceberg along the path, while avoiding failure modes.A hardware-in-the-loop (HIL) setup, containing position measurement errors, is developed for iceberg towing in the Marine Cybernetics Laboratory (MC Lab), using CS Enterprise I, a 1:50 scaled model vessel.
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Walgern, Julia. "Impact of Wind Farm Control Technologies on Wind Turbine Reliability." Thesis, Uppsala universitet, Elektricitetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388333.
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Cost efficient operation and maintenance strategies are crucial for reducing cost of wind energy. Since the regime change from feed-in tariffs to an auction-based bidding system for capacity in most European wind projects, levelized cost of energy is challenged constantly. Therefore, new technologies such as new controllers are developed to improve operation and to increase profit. Previous research studies demonstrated the advantage of increased power output of wake redirection control. However, understanding and quantifying the impact of wind farm control technologies on operation and maintenance strategies is inevitable to evaluate the economic feasibility of such new technologies. Thus, an event-based O&M simulation tool has been developed. Besides general modules, such as the wind turbine model, the weather forecasting model and a model for simulating corrective and planned maintenance, the developed tool also takes wake effects into account. This allows considering different power productions for each individual turbine and a failure rate distribution within the wind farm which is based on altering loads on the different components. Both aspects are driven by changes in operation when applying a new controller technology. Exemplarily, the economic feasibility of a closed-loop active wake steering control has been analysed. Main achievements of this study are the possibility to quantify the impact of the active wake steering control on O&M related KPIs. Results show that additional loads caused by applying yaw-misalignment and redirecting wake, lead to an increase in OPEX. However, the achieved energy production gain and thus related additional revenue exceeds additional cost in the case study. Nonetheless, the study reveals that the profitability of the controller is highly dependent on the electricity price which can be acquired during the wind farm’s lifetime.
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Lei, Ting. "Doubly-fed induction generator wind turbine modelling, control and reliability." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/doublyfed-induction-generator-wind-turbine-modelling-control-and-reliability(2ceb051a-a6fb-43e6-be40-a5023dae4bea).html.
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The trend of future wind farms moving further offshore requires much higher reliability for each wind turbine in order to reduce maintenance cost. The drive-train system and power electronic converter system have been identified as critical sub-assemblies that are subject to higher failure rates than the other sub-assemblies in a wind turbine. Modern condition monitoring techniques may help schedule the maintenance and reduce downtime. However, when it comes to offshore wind turbines, it is more crucial to reduce the failure rates (or reduce the stresses) for the wind turbines during operation since the harsh weather and a frequently inaccessible environment will dramatically reduce their availability once a failure happens. This research examines the mechanical, electrical and thermal stresses in the sub-assemblies of a doubly-fed induction generator (DFIG) wind turbine and how to reduce them by improved control strategies. The DFIG control system (the rotor-side and the grid-side converter control) as well as the wind turbine control system are well established. The interactions of these control systems have been investigated. This research examines several further strategies to reduce the mechanical and electrical stresses. The control system's coordination with the protection schemes (crowbar and dc-chopper) during a grid fault is presented as well. An electro-thermal model of the power converter has been developed to integrate with the DFIG wind turbine model, for the evaluation of the thermal stresses under different operating states and control schemes. The main contributions of this thesis are twofold. A first contribution is made by providing all the control loops with well-tuned controllers in a more integrated methodology. The dynamics of these controllers are determined from their mathematical models to minimize the interference between different control-loops and also to reduce the electrical transients. This thesis proposes a coordination strategy for the damping control, pitch control and crowbar protection which significantly reduces the mechanical oscillations. On the other hand, an integrated model of the wind turbine and converter electro-thermal system is established that can illustrate the performance integration with different control strategies.
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Sun, Zhouming. "Reliability-based method for stability of mine entry design and evaluation." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1575.
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Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 162 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 156-161).
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Saranga, Haritha. "Relevant condition parameter based approach to reliability and maintenance." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323982.
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Stineburg, Jeffrey. "Software reliability prediction based on design metrics." Virtual Press, 1999. http://liblink.bsu.edu/uhtbin/catkey/1154775.
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This study has presented a new model for predicting software reliability based on design metrics. An introduction to the problem of software reliability is followed by a brief overview of software reliability models. A description of the models is given, including a discussion of some of the issues associated with them. The intractability of validating life-critical software is presented. Such validation is shown to require extended periods of test time that are impractical in real world situations. This problem is also inherent in fault tolerant software systems of the type currently being implemented in critical applications today. The design metrics developed at Ball State University is proposed as the basis of a new model for predicting software reliability from information available during the design phase of development. The thesis investigates the proposition that a relationship exists between the design metric D(G) and the errors that are found in the field. A study, performed on a subset of a large defense software system, discovered evidence to support the proposition.Department of Computer Science
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Wingate, Guy A. S. "Software implemented fault tolerance for microprocessor controllers." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/5811/.
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It is generally accepted that transient faults are a major cause of failure in micro processor systems. Industrial controllers with embedded microprocessors are particularly at risk from this type of failure because their working environments are prone to transient disturbances which can generate transient faults. In order to improve the reliability of processor systems for industrial applications within a limited budget, fault tolerant techniques for uniprocessors are implemented. These techniques aim to identify characteristics of processor operation which are attributed to erroneous behaviour. Once detection is achieved, a programme of restoration activity can be initiated. This thesis initially develops a previous model of erroneous microprocessor behaviour from which characteristics particular to mal-operation are identified. A new technique is proposed, based on software implemented fault tolerance which, by recognizing a particular behavioural characteristic, facilitates the self-detection of erroneous execution. The technique involves inserting detection mechanisms into the target software. This can be quite a complex process and so a prototype software tool called Post-programming Automated Recovery UTility (PARUT) is developed to automate the technique's application. The utility can be used to apply the proposed behavioural fault tolerant technique for a selection of target processors. Fault injection and emulation experiments assess the effectiveness of the proposed fault tolerant technique for three application programs implemented on an 8, 16, and 32- bit processors respectively. The modified application programs are shown to have an improved detection capability and hence reliability when the proposed fault tolerant technique is applied. General assessment of the technique cannot be made, however, because its effectiveness is application specific. The thesis concludes by considering methods of generating non-hazardous application programs at the compilation stage, and design features for incorporation into the architecture of a microprocessor which inherently reduce the hazard, and increase the detection capability of the target software. Particular suggestions are made to add a 'PARUT' phase to the translation process, and to orientate microprocessor design towards the instruction opcode map.
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Kang'ethe, S. M. "An eigenstructure approach to the design of fault detection and isolation schemes for dynamic systems." Thesis, University of York, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235028.
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Lanz, Luciano Quinto. "Confiança e controles em relacionamentos interorganizacionais: um modelo de suas interações e de seus reflexos no desempenho." reponame:Repositório Institucional do BNDES, 2014. https://web.bndes.gov.br/bib/jspui/handle/1408/7061.
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Esta tese teve como objetivo principal propor um modelo analítico que relacione os efeitos dos mecanismos de controle nos processos de formação da confiança entre organizações envolvidas em alianças e parcerias, identificando seus reflexos no desempenho. O estudo buscou preencher uma lacuna na literatura, que na maioria dos casos trata os conceitos como antagônicos ou substitutos e não os relaciona diretamente com o desempenho. Esta pesquisa acredita que são conceitos complementares. A metodologia utilizada foi o estudo de caso, em uma aliança estratégica entre um banco de desenvolvimento (o BNDES) e 20 agentes financeiros em um fundo de aval, que concede garantias para micro, pequenas e médias empresas, com análise documental, entrevistas semiestruturadas e aplicação de questionários com escala tipo likert. Foram analisados os instrumentos contratuais, normativos e mecanismos de controle, a natureza de sua formalização e a percepção quanto a sua aplicação e seus efeitos sobre a dinâmica da confiança em ambos os níveis operacional e gerencial do relacionamento interorganizacional. Os resultados da análise dos contratos, normativos, entrevistas e questionários, indicaram que para ampliar suas operações, o fundo precisou equilibrar uma estrutura de governança com perspectiva estrutural, baseada em controles, com uma estrutura relacional, baseada em mecanismos informais, que gerasse confiança dos agentes financeiros. A principal contribuição deste estudo é esclarecer a relação confiança e controle no desenho de mecanismos de governança interorganizacional. Além disto, o modelo considera o tipo de organização, o nível hierárquico dos respondentes, e relacionamento passado entre as organizações. E finalmente, o estudo propõe uma avaliação de desempenho que considera não só as percepções expressas nas respostas aos questionários, mas também indicadores empresariais.This thesis aimed to propose an analytical model that relates the effects of control mechanisms in the formation of trust between organizations involved in alliances and partnerships, identifying their effects on performance. The study sought to fill a gap in the literature, which in most cases considers these as antagonistic or substitutes concepts and not directly related to performance. This research believes that these are complementary concepts. The methodology used was the case study of a strategic alliance between a development bank (BNDES) and 20 financial agents in a guarantee fund, which guarantees for micro, small and medium enterprises, with document analysis, semi-structured interviews and application of questionnaires with Likert type scale. The study analyses contractual, regulatory and control mechanisms instruments, the nature of formalization, the perception of implementation and its effects on the dynamics of trust at both operational and management levels of interorganizational relations. The results of contracts, regulatory, interviews and questionnaires analysis indicated that to expand its operations, the fund need to balance governance with structural perspective, based in controls mechanisms with a relational structure, based on informal mechanisms that build financial agents trust. The main contribution of this study is to clarify the relationship between trust and control in the design of interorganizational governance mechanisms. Moreover, the framework considers the organization type, respondents' hierarchical level, and the previous relationship between organizations. And finally the study proposes a performance evaluation that considers not only the perceptions from the questionnaires, but also business indicators.
Tese (doutorado) - Pontifícia Universidade Católica do Rio de Janeiro. Departamento de Administração, 2014.
Bibliografia: p. 158-199
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McCartney, Mark. "SRAM Reliability Improvement Using ECC and Circuit Techniques." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/531.
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Reliability is of the utmost importance for safety of electronic systems built for the automotive, industrial, and medical sectors. In these systems, the embedded memory is especially sensitive due to the large number of minimum-sized devices in the cell arrays. Memory failures which occur after the manufacture-time burnin testing phase are particularly difficult to address since redundancy allocation is no longer available and fault detection schemes currently used in industry generally focus on the cell array while leaving the peripheral logic vulnerable to faults. Even in the cell array, conventional error control coding (ECC) has been limited in its ability to detect and correct failures greater than a few bits, due to the high latency or area overhead of correction [43]. Consequently, improvements to conventional memory resilience techniques are of great importance to continued reliable operation and to counter the raw bit error rate of the memory arrays in future technologies at economically feasible design points [11, 36, 37, 53, 56, 70]. In this thesis we examine the landscape of design techniques for reliability, and introduce two novel contributions for improving reliability with low overhead. To address failures occurring in the cell array, we have implemented an erasurebased ECC scheme (EB-ECC) that can extend conventional ECC already used in memory to correct and detect multiple erroneous bits with low overhead. An important component of this scheme is the method for detecting erasures at runtime; we propose a novel ternary-output sense amplifier design which can reduce the risk of undetected read latency failures in small-swing bitline designs. While most study has focused on the static random access memory (SRAM) cell array, for high-reliability products, it is important to examine the effects of failures on the peripheral logic as well. We have designed a wordline assertion comparator (WLAC) which has lower area overhead in large cache designs than competing techniques in the literature to detect address decoder failure.
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Lenz, Malte, and Johan Rhodin. "Reliability calculations for complex systems." Thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69952.
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Functionality for efficient computation of properties of system lifetimes was developed, based on the Mathematica framework. The model of these systems consists of a system structure and the components independent lifetime distributions. The components are assumed to be non-repairable. In this work a very general implementation was created, allowing a large number of lifetime distributions from Mathematica for all the component distributions. All system structures with a monotone increasing structure function can be used. Special effort has been made to compute fast results when using the exponential distribution for component distributions. Standby systems have also been modeled in similar generality. Both warm and cold standby components are supported. During development, a large collection of examples were also used to test functionality and efficiency. A number of these examples are presented. The implementation was evaluated on large real world system examples, and was found to be efficient. New results are presented for standby systems, especially for the case of mixed warm and cold standby components.
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Kesupile, Galeboe. "Cumulative sum quality control charts design and applications." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/17212.
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Includes bibliographical references (pages 165-169).Classical Statistical Process Control Charts are essential in Statistical Control exercises and thus constantly obtained attention for quality improvements. However, the establishment of control charts requires large-sample data (say, no less than I 000 data points). On the other hand, we notice that the small-sample based Grey System Theory Approach is well-established and applied in many areas: social, economic, industrial, military and scientific research fields. In this research, the short time trend curve in terms of GM( I, I) model will be merged into Shewhart and CU SUM two-sided version control charts and establish Grey Predictive Shewhart Control chart and Grey Predictive CUSUM control chart. On the other hand the GM(2, I) model is briefly checked its of how accurate it could be as compared to GM( I, 1) model in control charts. Industrial process data collected from TBF Packaging Machine Company in Taiwan was analyzed in terms of these new developments as an illustrative example for grey quality control charts.
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Le, Dinh Tuan Computer Science & Engineering Faculty of Engineering UNSW. "Data reliability control in wireless sensor networks for data streaming applications." Publisher:University of New South Wales. Computer Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43328.
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This thesis contributes toward the design of a reliable and energy-efficient transport system for Wireless Sensor Networks. Wireless Sensor Networks have emerged as a vital new area in networking research. In many Wireless Sensor Network systems, a common task of sensor nodes is to sense the environment and send the sensed data to a sink node. Thus, the effectiveness of a Wireless Sensor Network depends on how reliably the sensor nodes can deliver their sensed data to the sink. However, the sensor nodes are susceptible to loss for various reasons when there are dynamics in wireless transmission medium, environmental interference, battery depletion, or accidentally damage, etc. Therefore, assuring reliable data delivery between the sensor nodes and the sink in Wireless Sensor Networks is a challenging task. The primary contributions of this thesis include four parts. First, we design, implement, and evaluate a cross-layer communication protocol for reliable data transfer for data streaming applications in Wireless Sensor Networks. We employ reliable algorithms in each layer of the communication stack. At the MAC layer, a CSMA MAC protocol with an explicit hop-by-hop Acknowledgment loss recovery is employed. To ensure the end-to-end reliability, the maximum number of retransmissions are estimated and used at each sensor node. At the transport layer, an end-to-end Negative Acknowledgment with an aggregated positive Acknowledgment mechanism is used. By inspecting the sequence numbers on the packets, the sink can detect which packets were lost. In addition, to increase the robustness of the system, a watchdog process is implemented at both base station and sensor nodes, which enable them to power cycle when an unexpected fault occurs. We present extensive evaluations, including theoretical analysis, simulations, and experiments in the field based on Fleck-3 platform and the TinyOS operating system. The designed network system has been working in the field for over a year. The results show that our system is a promising solution to a sustainable irrigation system. Second, we present the design of a policy-based Sensor Reliability Management framework for Wireless Sensor Networks called SRM. SRM is based on hierarchical management architecture and on the policy-based network management paradigm. SRM allows the network administrators to interact with the Wireless Sensor Network via the management policies. SRM also provides a self-control capability to the network. This thesis restricts SRM to reliability management, but the same framework is also applicable for other management services by providing the management policies. Our experimental results show that SRM can offer sufficient reliability to the application users while reducing energy consumption by more than 50% compared to other approaches. Third, we propose an Energy-efficient and Reliable Transport Protocol called ERTP, which is designed for data streaming applications in Wireless Sensor Networks. ERTP is an adaptive transport protocol based on statistical reliability that ensures the number of data packets delivered to the sink exceeds the defined threshold while reducing the energy consumption. Using a statistical reliability metric when designing a reliable transport protocol guarantees the delivery of adequate information to the users, and reduces energy consumption when compared to the absolute reliability. ERTP uses hop-by-hop Implicit Acknowledgment with a dynamically updated retransmission timeout for packet loss recovery. In multihop wireless networks, the transmitter can overhear a forwarding transmission and interpret it as an Implicit Acknowledgment. By combining the statistical reliability and the hop-by-hop Implicit Acknowledgment loss recovery, ERTP can offer sufficient reliability to the application users with minimal energy expense. Our extensive simulations and experimental evaluations show that ERTP can reduce energy consumption by more than 45% when compared to the state-of- the-art protocol. Consequently, sensor nodes are more energy-efficient and the lifespan of the unattended Wireless Sensor Network is increased. In Wireless Sensor Networks, sensor node failures can create network partitions or coverage loss which can not be solved by providing reliability at higher layers of the protocol stack. In the final part of this thesis, we investigate the problem of maintaining the network connectivity and coverage when the sensor nodes are failed. We consider a hybrid Wireless Sensor Network where a subset of the nodes has the ability to move at a high energy expense. When a node has low remaining energy (dying node) but it is a critical node which constitutes the network such as a cluster head, it will seek a replacement. If a redundant node is located in the transmission range of the dying node and can fulfill the network connectivity and coverage requirement, it can be used for substitution. Otherwise, a protocol should be in place to relocate the redundant sensor node for replacement. We propose a distributed protocol for Mobile Sensor Relocation problem called Moser. Moser works in three phases. In the first phase, the dying node determines if network partition occurs, finds an available mobile node, and asks for replacement by using flooding algorithm. The dying node also decides the movement schedule of the available mobile node based on certain criteria. The second phase of the Moser protocol involves the actual movement of the mobile nodes to approach the location of the dying node. Finally, when the mobile node has reached the transmission of the dying node, it communicates to the dying nodes and moves to a desired location, where the network connectivity and coverage to the neighbors of the dying nodes are preserved.
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Forrisi, Ivano. "Contribution to renewable systems grid connected : control, stability analysis and reliability." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0345/document.
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Cette thèse a pour but l'analyse d'un système photovoltaïque connecté au réseau électrique en prenant en compte le contrôle, l'étude de la stabilité et la fiabilité. Un onduleur de type 2-Niveau a été comparé avec un onduleur multi-niveaux appelé Neutral Point Clamped. Les avantages et désavantage de chaque topologie ont été analysé en considérant l'efficacité énergétique, l'optimisation de l'injection de l'énergie sur le réseau électrique et la fiabilité du système. Pour le contrôle du courant de sortie de l'onduleur, ont été proposées deux solutions : un contrôle basé sur la théorie de la platitude et un contrôle par passivité. Ces deux différents contrôles sont comparés par rapport à la robustesse, la complexité et le nombre de capteurs utilisés. Il a été montré que les deux contrôles sont capables de gérer la problématique de la résonance du filtre LCL. Pour augmenter l'efficacité de l'algorithme MPPT dans une configuration Distributed-MPPT avec la connexion en série des deux sorties des convertisseurs boost, une nouvelle technique a été proposé pour l'équilibrage des tension d'entrée d'un onduleur NPC. En utilisant un outil appelé TPtool, un étude de la stabilité large signal par "Higher-Order-Singular-Value-Decomposition" a été présenté et comparé avec une méthode basée sur les modèles Takagi-Sugeno pour des systèmes non-linéaires. Finalement, l'onduleur 2-Niveaux est comparé avec deux multi-niveaux différents (NPP et NPC) en termes de disponibilité, en prenant en compte les niveaux de redondance des convertisseurs. Pour analyser la disponibilité, a été considérée la théorie des chaines de Markov et pour l'implémentation, le logiciel GRIF a été utiliséThe aim of this PhD thesis is to analyze a PV-grid connected system in terms of control, stability and reliability. A comparison between a classical 2-Level inverter and a multilevel NPC is presented. The advantages and weakness of both the converters are analyzed with respect to the power efficiency, optimization of the energy injection to the grid and reliability of the system. In order to control the inverter output current, two different solutions are proposed: flatness-based control and passivity-based control. These controls are compared in terms of robustness, complexity and number of sensors used. It is shown that both the controls may manage the resonance problems due to a LCL filter. For increasing the efficiency of the MPPT in a configuration Distributed-MPPT with connections in series of the boost converters outputs, a novel technique for the dc voltages balancing of a NPC inverter is proposed. A large stability analysis using "Higher-Order-Singular-Value-Decomposition" is presented and compared with Takagi-Sugeno approach for nonlinear systems. Finally, 2-Level inverter is compared with two multilevel inverters (NPC and NPP) in terms of availability, considering the redundancy levels of the converters. To analyze the systems availability, the Markov chains theory is considered and it is implemented on GRIF
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OLIVEIRA, PAULO GUILHERME OLIVEIRA DE. "RELIABILITY STUDY OF SUBSURFACE SAFETY VALVE CONTROL SYSTEM IN OIL WELLS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27632@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROOs desafios na construção de poços de petróleo vêm aumentando ao longo do tempo, seja pelo aumento das dificuldades técnicas devido à maior complexidade das áreas a serem desenvolvidas, sejam pelas melhorias nas regras dos órgãos reguladores visando aumentar a segurança. Existem dois pilares que devem nortear um projeto de um poço de petróleo: segurança e produtividade. O equipamento denominado dispositivo de segurança de sub-superfície e seu sistema de controle podem ser considerados importantes para os dois, pois caso o sistema falhe, obtendo-se um fechamento prematuro do poço, afetará diretamente a produção. Por outro lado, caso a falha ocorra em uma tentativa de fechamento, poderá influenciar nas consequências de um desastre, o que afetaria tanto pessoas como o meio ambiente. O objetivo deste estudo e comparar a confiabilidade de alguns modelos de sistemas de controle do dispositivo de segurança de sub-superfície, levando em consideração as disposições dos equipamentos ao longo do sistema e suas respectivas taxas de falha. Além disso, a maioria dos estudos de confiabilidade realizados nesta área tem como foco principal a segurança, porém este estudo visa obter um foco de eficiência de produção, e as análises serão baseadas em comparações entre algumas configurações disponíveis do sistema, entre componentes em série e em paralelo, utilizando o modelo de análise de confiabilidade markoviano.
The challenges in well construction have been increasing over time, sometimes by increasing the technical difficulties due to the greater complexity of the areas to be developed, sometimes by the improvements in the rules of regulatory agencies to increase security. There are two pillars that should guide the project of a petroleum well: safety and productivity. The equipment called Subsurface Safety Valve and its control system can be considered important for both pillars, because if the system fails resulting in a premature well closure, it will directly affect the production. On the other hand, if the failure occurs in an attempt to closing it, may influence the consequence of a disaster, which would affect both people and the environment. The objective of this study is to compare the reliability of some control systems models taking into account the equipment positions throughout the system and their failure rates. Furthermore, most reliable studies conducted in this area has mainly focused on safety, but this study has a focus on production efficiency, and the analysis will be based on comparisons between some configurations available for subsurface safety valves control system, including serial and parallel components, using the model of Markov reliability analysis.
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Tomkins, Susannah Chloe. "Proxy respondents in a case-control study : validity, reliability and impact." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2006. http://researchonline.lshtm.ac.uk/768483/.
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In many research settings, the study subject is unable to provide responses, requiring researchers to find alternative respondents. This thesis explores the use of proxy respondents in a case control study of premature mortality among Russian men of working age (25-54 years). Data obtained from proxy respondents is explored in four ways. Firstly, proxy questionnaire responses are validated against external data sources which were routinely collected, blind to case-control status - the city alcohol treatment clinic (Narcology Dispensary), Social Security and Police records. Secondly, agreement between proxy and index (control) responses to questions about alcohol use, tobacco use, health and socioeconomic factors is explored. Thirdly, the effect of proxy type is explored by examination of proxy-proxy and index-proxy agreement in a subset of households in which two proxy interviews were obtained. Finally, the impact on analysis outcomes is explored by mortality analyses using proxy versus index data. Cohen's kappa coefficient was used to explore inter-respondent agreement. Differences in agreement between pairs of respondents were examined using Agresti's loglinear model, and the directionality of disagreements were evaluated using McNemar's test. Findings confirm some assertions in the literature. Questions about easily observable characteristics and behaviours, avoiding excessive detail, subjective or sensitive topics, elicit valid proxy responses. Proxies tend to over-report alcohol use, but provide particularly valid responses about tobacco use and socioeconomic factors. Validity was highest among proxies who were the index's spouse. However, further exploration suggested that men who have spouses differ in their behaviour from men who do not in ways which affect its reporting. There was little additional evidence that proxy characteristics affect validity. The use of proxy responses biases odds ratios in this case control study toward more conservative estimates. These findings are generalisable to study settings which employ a protocol to ensure selection of the best available proxy.
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You, Weizhen. "Reliability assessment of TMD-based control structures : A Statistical Learning Perspective." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC001.
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L’étude de la fiabilité structurelle concerne principalement l’évaluation et la prévision du risque de violation de l'état limite pour une structure d'ingénierie à n'importe quel stade de son la vie. L’évaluation de la fiabilité contribue à améliorer la conception de la structure et la qualité du produit, qui revêt une grande importance pour les entreprises et les consommateurs. C'est aussi la base de modélisation et prédiction de la fiabilité. Le contrôle des vibrations est une technique permettant de réduire la énergie d'une structure vibrante lorsqu'elle est excitée par des forces extérieures. Cette technique est largement utilisé dans divers systèmes, tels que les bâtiments, les ponts, les machines-outils et véhicules. La prévision de fiabilité aide les entreprises à planifier la production et à mettre en œuvre la maintenance préventive. Pour faire les prédictions, un modèle de fiabilité est d'abord déterminé. En raison de facteurs intérieurs et extérieurs complexes, la structure les propriétés dévient toujours leurs valeurs de conception. Les incertitudes structurelles jouent un rôle important dans la modélisation de la fiabilité. Les modèles de fiabilité traditionnels sont généralement sur la base d'informations a priori et de connaissances professionnelles, ce qui était irréaliste pour les systèmes d’aujourd’hui, plus complexes et non linéaires en raison des technologies avancées. méthodologies de conception. Dans cette situation, une attention croissante a été accordée à approches d'apprentissage statistique non paramétriques. Vu comme une classification / regression procédure, la tâche de prédiction peut être réalisée par des modèles d’apprentissage automatique, tels que méthodes d’arborescence, machines à vecteurs de support, réseaux de neurones artificiels, etc. Les modèles attirent de plus en plus l'attention dans les recherches récemment publiées. Dans cette recherche, nous avons étudié plusieurs modèles d’apprentissage automatique tels que: Forêts aléatoires, Boosting adaptatif, Machines à vecteurs de support, Neural artificial Réseaux, etc. En outre, nous avons développé une nouvelle méthode d'évaluation de la fiabilité du système. pour les systèmes structurels complexes. Ces méthodes étendent les méthodes d'apprentissage statistique sur l’analyse et la prévision de la fiabilité structurelleThe study of structural reliability mainly concerns the evaluation and prediction of the risk of limit state violation for an engineering structure at any stage of its life. Reliability evaluation helps improve structure design and product quality, which is of great significance for companies and consumers. It is also the basis of reliability modeling and prediction. Vibration control is a technique to reduce the energy of a vibrating structure when it is excited by external forces. This technique is widely used in various systems, such as buildings, bridges, machine tools and vehicles. Reliability prediction helps companies make production planning and implement preventive maintenance. To do the predictions, a reliability model is firstly determined. Due to complex interior and exterior factors, the structure properties always deviate their design values. The structural uncertainties play an important role in reliability modeling. Traditional reliability models are commonly based on a priori information and professional knowledge, which has been unrealistic for today’s systems that are more complex and nonlinear due to advanced design methodologies. In this situation, growing attention has been paid to non-parametric statistical learning approaches. Seen as a classification/ regression procedure, the prediction task can be realized by machine learning models, such as Tree methods, Support vector machines, Artificial Neural Networks, etc. These models are attracting more and more attention in recent published researches. In this research, we have investigated several machine learning models such as Random Forests, Adaptive Boosting, Support vector machines, Artificial Neural Networks, etc. Besides we developed a new system reliability assessment method for complex structural systems. These methods extend statistical learning methods on structural reliability analysis and prediction
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Campean, Ioan Felician. "Product reliability analysis and prediction : applications to mechanical systems." Thesis, Bucks New University, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.714448.
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Al-Saadi, S. "Development of a reliability and metrology assessment methodology : maintenance data from the GMC Fire Service for fire fighting vehicles and appliances are analysed to assess reliability performance and to determine relationships between engineering metrology, reliability and quality assurance aspects." Thesis, University of Bradford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264585.
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Muniraj, Devaprakash. "On the Security and Reliability of Fixed-Wing Unmanned Aircraft Systems." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102702.
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The focus of this dissertation is on developing novel methods and extending existing ones to improve the security and reliability of fixed-wing unmanned aircraft systems (UAS). Specifically, we focus on three strands of work: i) designing UAS controllers with performance guarantees using the robust control framework, ii) developing tools for detection and mitigation of physical-layer security threats in UAS, and iii) extending tools from compositional verification to design and verify complex systems such as UAS.
Under the first category, we use the robust H-infinity control approach to design a linear parameter-varying (LPV) path-following controller for a fixed-wing UAS that enables the aircraft to follow any arbitrary planar curvature-bounded path under significant environmental disturbances. Three other typical path-following controllers, namely, a linear time-invariant H-infinity controller, a nonlinear rate-tracking controller, and a PID controller, are also designed. We study the relative merits and limitations of each approach and demonstrate through extensive simulations and flight tests that the LPV controller has the most consistent position tracking performance for a wide array of geometric paths. Next, convex synthesis conditions are developed for control of distributed systems with uncertain initial conditions, whereby independent norm constraints are placed on the disturbance input and the uncertain initial state. Using this approach, we design a distributed controller for a network of three fixed-wing UAS and demonstrate the improvement in the transient response of the network when switching between different trajectories.
Pertaining to the second strand of this dissertation, we develop tools for detection and mitigation of security threats to the sensors and actuators of UAS. First, a probabilistic framework that employs tools from statistical analysis to detect sensor attacks on UAS is proposed. By incorporating knowledge about the physical system and using a Bayesian network, the proposed approach minimizes the false alarm rates, which is a major challenge for UAS that operate in dynamic and uncertain environments. Next, the security vulnerabilities of existing UAS actuators are identified and three different methods of differing complexity and effectiveness are proposed to detect and mitigate the security threats. While two of these methods involve developing algorithms and do not require any hardware modification, the third method entails hardware modifications to the actuators to make them resilient to malicious attacks. The three methods are compared in terms of different attributes such as computational demand and detection latency.
As for the third strand of this dissertation, tools from formal methods such as compositional verification are used to design an unmanned multi-aircraft system that is deployed in a geofencing application, where the design objective is to guarantee a critical global system property. Verifying such a property for the multi-aircraft system using monolithic (system-level) verification techniques is a challenging task due to the complexity of the components and the interactions among them. To overcome these challenges, we design the components of the multi-aircraft system to have a modular architecture, thereby enabling the use of component-based reasoning to simplify the task of verifying the global system property. For component properties that can be formally verified, we employ results from Euclidean geometry and formal methods to prove those properties. For properties that are difficult to be formally verified, we rely on Monte Carlo simulations. We demonstrate how compositional reasoning is effective in reducing the use of simulations/tests needed in the verification process, thereby increasing the reliability of the unmanned multi-aircraft system.Doctor of Philosophy
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Yu, Hang. "Reliability-based design optimization of structures : methodologies and applications to vibration control." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00769937.
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Deterministic design optimization is widely used to design products or systems. However, due to the inherent uncertainties involved in different model parameters or operation processes, deterministic design optimization without considering uncertainties may result in unreliable designs. In this case, it is necessary to develop and implement optimization under uncertainties. One way to deal with this problem is reliability-based robust design optimization (RBRDO), in which additional uncertainty analysis (UA, including both of reliability analysis and moment evaluations) is required. For most practical applications however, UA is realized by Monte Carlo Simulation (MCS) combined with structural analyses that renders RBRDO computationally prohibitive. Therefore, this work focuses on development of efficient and robust methodologies for RBRDO in the context of MCS. We presented a polynomial chaos expansion (PCE) based MCS method for UA, in which the random response is approximated with the PCE. The efficiency is mainly improved by avoiding repeated structural analyses. Unfortunately, this method is not well suited for high dimensional problems, such as dynamic problems. To tackle this issue, we applied the convolution form to compute the dynamic response, in which the PCE is used to approximate the modal properties (i.e. to solve random eigenvalue problem) so that the dimension of uncertainties is reduced since only structural random parameters are considered in the PCE model. Moreover, to avoid the modal intermixing problem when using MCS to solve the random eigenvalue problem, we adopted the MAC factor to quantify the intermixing, and developed a univariable method to check which variable results in such a problem and thereafter to remove or reduce this issue. We proposed a sequential RBRDO to improve efficiency and to overcome the nonconvergence problem encountered in the framework of nested MCS based RBRDO. In this sequential RBRDO, we extended the conventional sequential strategy, which mainly aims to decouple the reliability analysis from the optimization procedure, to make the moment evaluations independent from the optimization procedure. Locally "first-torder" exponential approximation around the current design was utilized to construct the equivalently deterministic objective functions and probabilistic constraints. In order to efficiently calculate the coefficients, we developed the auxiliary distribution based reliability sensitivity analysis and the PCE based moment sensitivity analysis. We investigated and demonstrated the effectiveness of the proposed methods for UA as well as RBRDO by several numerical examples. At last, RBRDO was applied to design the tuned mass damper (TMD) in the context of passive vibration control, for both deterministic and uncertain structures. The associated optimal designs obtained by RBRDO cannot only reduce the variability of the response, but also control the amplitude by the prescribed threshold.
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Pabst, Ilona [Verfasser]. "On Modeling, Analysis, and Synthesis of Generalized Reliability Control Systems / Ilona Pabst." Aachen : Shaker, 2005. http://d-nb.info/1186575859/34.
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Sares, Elizabeth A. "Reliability of a Novel Trunk Motor Neuroimaging Paradigm." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1556124412110247.
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Abed, M. H. "Status and structure of quality and reliability management systems : Investigation of the organisation and structure of reliability and quality management systems in UK and European industries to establish benefits of such programmes." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234688.
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Liu, Chi-Chao. "A comparison between the Weibull and lognormal models used to analyse reliability data." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362886.
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Walters, Ryp R. "A control system for laser trimming thick film resistors and the reliability effects." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-01312009-063402/.
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Borman, Duncan James. "Mechatronic system topology and control for high-speed, high-reliability textile inkjet printing." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427769.
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Alkhatib, K. Y. "Analytical redundancy scheme for improving reliability of automatic flight control systems for aircraft." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/31989.
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Any redundancy scheme in aircraft control systems is usually considered separately from the control algorithms involved. All feedback control systems are usually designed under the assumption that their sensors will not fail. When the integrity requirements demand it, then a redundancy scheme must be designed to provide any required measurements with only extremely short interruptions to normal service being caused by failures of individual sensors.
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Gopala, Praveen Kumar. "Feedback in wireless networks cross-layer design, secrecy and reliability /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1189452535.
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Clark, Howard. "The use of simulation for the investigation of quality economics in a cell-based manufacturing environment." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263390.
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This thesis is an investigation into the use of simulation for the study of quality economics within a cell-based manufacturing environment. Quality is, for the purposes of this report, considered to mean conformance to specification. This research identified two distinct areas of study that could be considered part of quality economics. The economic design of quality control procedures is concerned with the "micro" side of quality economics, focusing on single processes, whilst quality costing systems represent the "macro" side, focusing on entire production lines, departments or organisations. A critical analysis of these areas suggested a number of deficiencies. In addition, a number of economic quality models were considered. These were found to focus on the "macro" side of quality economics, with no consideration of the effect of specific changes to specific processes - the "micro" side. It was suggested that simulation would be a suitable approach for overcoming some of these deficiencies. The precedent for the use of simulation to investigate quality economics is considered, with the conclusion that none of the existing approaches reviewed were able to model the manufacturing systems under consideration in sufficient detail. Therefore, a new approach is outlined, and the thesis then describes the development and validation of this approach. A number of examples are given that are intended to both illustrate the simulation approach and, hopefully, provide certain generic information that can be applied to any similar manufacturing process. Conclusions are drawn regarding the success of the project relative to the initial aims, and the contribution to our understanding of quality economics. Finally, a number of recommendations for further work are given.
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Abrons, Andrew. "An investigation into the applicability of reliability centred maintenance and expert systems technology for developing preventative maintenance in the steel industry." Thesis, University of the West of England, Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240857.
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Hogan, Paul Anthony. "A knowledge-based system for automated fault analysis of hydraulic systems." Thesis, University of Bath, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332776.
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Gomm, James Barry. "On-line detection of fault conditions in controlled industrial processes." Thesis, Liverpool John Moores University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304482.
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Pereira-Leite, Margarida Maria Alvim. "A procedure for monitoring the mean of autocorrelated industrial data." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333934.
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Owen, Bryn David. "The design and implementation of a systems model to meet ISO 9000-1987." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336078.
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Odoom, Emmanuel Ricky. "A methodology for operational reliability programme development and assessment with application to ship propulsion plant." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322014.
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Piercy, Neil Philip. "A redundancy approach to sensor failure detection : with application to turbofan engines." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305488.
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Wang, Duan Qiang. "Strain measurement using neutron diffraction." Thesis, Open University, 1996. http://oro.open.ac.uk/57651/.
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This thesis contains a study of improvement and application of strain measurement technique using neutron diffraction. A dedicated neutron strain scanner - ENGIN, funded by Ee. has been developed at ISIS. It has two radial collimators, allowing for the first time, measurements taken simultaneously at two orthogonal directions; uses Pawley refinement permitting both whole pattern and individual peak profile analysis and its positioner allow's specimens weighing 250 kg to be placed with an accuracy of 100 um. Strain measurement using neutron diffraction has been investigated under two extreme circumstances: very shallow (within 1 mm near surface) and very deep in materials (hundred of mm). Near-surface measurement requires both the accurate determination of the effective measurement position associated with precise location of specimen, calculation of centroid and correction for an anomalous near-surface effect. The strain measurements on a shot-peened surface in titanium alloy were carried out using the methodology mentioned above. The result is comparable to that obtained from X-ray diffraction. The latter was exploited by studying the effect of wavelength-dependent attenuation in materials. Experiments and theoretical analysis on aluminium and iron show that the effect is small for a strain scanner using radial collimator and time-of-flight technique. However, the reduction of the diffraction peak intensity, as a function of the amount of material in the beam path, reveals that great care should be taken when measuring texture as a function of depth in materials. The neutron diffraction technique was applied to several sets of engineering strain measurements. Firstly, 3-D residual stresses surrounding a cold expanded hole in a high strength aluminium alloy plate were measured. The result agrees well with that from modified Sachs' method after taking the effect of gauge volume averaging into account. Second, measurements of strain distributions in a Q-joint under zero and 30 kN load have been carried out, which provides a confirmation of the excellence of the joint design as the fastener system has completely shielded the fastener hole from deleterious tensile strains under operational loading. Finally, calibration strain measurement for an energy dispersive neutron transmission spectrometer was performed for the first time and it is found that the transmission spectrometer is feasible for strain and phase transformation measurement.