Дисертації з теми "Tolerance optimization"
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Shehabi, Murtaza Kaium. "Cost tolerance optimization for piecewise continuous cost tolerance functions." Ohio : Ohio University, 2002. http://www.ohiolink.edu/etd/view.cgi?ohiou1174937670.
Yue, Junping. "A computerized optimization method for tolerance control." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07112009-040315/.
Jrad, Mohamed. "Multidisciplinary Optimization and Damage Tolerance of Stiffened Structures." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52276.
Ph. D.
Arenbeck, Henry. "Efficient Reliability-Based Tolerance Optimization for Multibody Systems." Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/190380.
Barraja, Mathieu. "TOLERANCE ALLOCATION FOR KINEMATIC SYSTEMS." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_theses/315.
Chen, Jack Szu-Shen. "Distortion-free tolerance-based layer setup optimization for layered manufacturing." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27268.
Burlyaev, Dmitry. "Design, Optimization, and Formal Verification of Circuit Fault-Tolerance Techniques." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAM058/document.
Technology shrinking and voltage scaling increase the risk of fault occurrences in digital circuits. To address this challenge, engineers use fault-tolerance techniques to mask or, at least, to detect faults. These techniques are especially needed in safety critical domains (e.g., aerospace, medical, nuclear, etc.), where ensuring the circuit functionality and fault-tolerance is crucial. However, the verification of functional and fault-tolerance properties is a complex problem that cannot be solved with simulation-based methodologies due to the need to check a huge number of executions and fault occurrence scenarios. The optimization of the overheads imposed by fault-tolerance techniques also requires the proof that the circuit keeps its fault-tolerance properties after the optimization.In this work, we propose a verification-based optimization of existing fault-tolerance techniques as well as the design of new techniques and their formal verification using theorem proving. We first investigate how some majority voters can be removed from Triple-Modular Redundant (TMR) circuits without violating their fault-tolerance properties. The developed methodology clarifies how to take into account circuit native error-masking capabilities that may exist due to the structure of the combinational part or due to the way the circuit is used and communicates with the surrounding device.Second, we propose a family of time-redundant fault-tolerance techniques as automatic circuit transformations. They require less hardware resources than TMR alternatives and could be easily integrated in EDA tools. The transformations are based on the novel idea of dynamic time redundancy that allows the redundancy level to be changed "on-the-fly" without interrupting the computation. Therefore, time-redundancy can be used only in critical situations (e.g., above Earth poles where the radiation level is increased), during the processing of crucial data (e.g., the encryption of selected data), or during critical processes (e.g., a satellite computer reboot).Third, merging dynamic time redundancy with a micro-checkpointing mechanism, we have created a double-time redundancy transformation capable of masking transient faults. Our technique makes the recovery procedure transparent and the circuit input/output behavior remains unchanged even under faults. Due to the complexity of that method and the need to provide full assurance of its fault-tolerance capabilities, we have formally certified the technique using the Coq proof assistant. The developed proof methodology can be applied to certify other fault-tolerance techniques implemented through circuit transformations at the netlist level
Morales, Reyes Alicia. "Fault tolerant and dynamic evolutionary optimization engines." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4882.
KANSARA, SHARAD MAHENDRA. "AN EFFICIENT SEQUENTIAL INTEGER OPTIMIZATION TECHNIQUE FOR PROCESS PLANNING AND TOLERANCE ALLOCATION." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069798466.
Izosimov, Viacheslav. "Scheduling and Optimization of Fault-Tolerant Embedded Systems." Licentiate thesis, Linköping University, Linköping University, ESLAB - Embedded Systems Laboratory, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7654.
Safety-critical applications have to function correctly even in presence of faults. This thesis deals with techniques for tolerating effects of transient and intermittent faults. Reexecution, software replication, and rollback recovery with checkpointing are used to provide the required level of fault tolerance. These techniques are considered in the context of distributed real-time systems with non-preemptive static cyclic scheduling.
Safety-critical applications have strict time and cost constrains, which means that not only faults have to be tolerated but also the constraints should be satisfied. Hence, efficient system design approaches with consideration of fault tolerance are required.
The thesis proposes several design optimization strategies and scheduling techniques that take fault tolerance into account. The design optimization tasks addressed include, among others, process mapping, fault tolerance policy assignment, and checkpoint distribution.
Dedicated scheduling techniques and mapping optimization strategies are also proposed to handle customized transparency requirements associated with processes and messages. By providing fault containment, transparency can, potentially, improve testability and debugability of fault-tolerant applications.
The efficiency of the proposed scheduling techniques and design optimization strategies is evaluated with extensive experiments conducted on a number of synthetic applications and a real-life example. The experimental results show that considering fault tolerance during system-level design optimization is essential when designing cost-effective fault-tolerant embedded systems.
Wang, Pei. "Simultaneously solving process selection, machining parameter optimization and tolerance design problems: A bi-criterion approach." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26544.
Diril, Abdulkadir Utku. "Circuit Level Techniques for Power and Reliability Optimization of CMOS Logic." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6929.
Rajagopalan, Mohan. "Optimizing System Performance and Dependability Using Compiler Techniques." Diss., Tucson, Arizona : University of Arizona, 2006. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1439%5F1%5Fm.pdf&type=application/pdf.
Lima, Alice Medeiros de. "Nonlinear constrained optimization with flexible tolerance method: improvement and application in systems synthesis of mass integration." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/3967.
Universidade Federal de Sao Carlos
Este trabalho visa a otimização não-linear restrita usando o Método das Tolerâncias Flexíveis (FTM) e na aplicação do mesmo na síntese de sistemas de integração mássica. A integração mássica é uma técnica que permite a compreensão global do fluxo de massa dentro do processo, e emprega tais conhecimentos na identificação de melhorias de desempenho e otimização da geração e mapeamento de espécies ao longo do processo. A integração de massa baseia-se nos princípios fundamentais da engenharia química combinada com a análise do sistema usando ferramentas gráficas e de otimização. Neste contexto, o método direto de otimização foi usado como base para melhorias a fim de tornar possível sua aplicação em problemas de síntese de processo, especialmente a integração de massa. O Método das Tolerância Flexíveis é um método direto de otimização que apresenta algumas vantagens como simplicidade e a capacidade de lidar com igualdade e desigualdade sem empregar o cálculo de derivadas. O método utiliza duas buscas para satisfazer a restrição de viabilidade. A busca externa é uma variação do método de Nelder-Mead (ou o método Poliedro Flexível ou FPM) que minimiza a função objetivo. A busca interna minimiza o valor da função formada pelas restrições de igualdade e/ou desigualdade do problema. Esta busca interna pode ser realizada por qualquer método de otimização não linear irrestrita. Neste trabalho, o método das tolerâncias flexíveis foi hibridizado com diferentes métodos irrestritos para realizar a busca interna: BFGS (Método de Broyden, Fletcher, Goldfarb and Shanno) e Powell modificado. O método estocástico do Enxame de Partículas (PSO) também foi empregado para efetuar a inicialização e geração do ponto de partida viável para sequencial aplicação do método deiii terminístico (FTM e modificações). Outras modificações testadas foram o escalonamento de variáveis, a utilização de parâmetros adaptativos Nelder-Mead e a adição de uma barreira. Os algoritmos propostos neste trabalho foram aplicados a um conjunto de problemas nãolineares restritos que compreende problemas de otimização reais. Os códigos que apresentaram melhor desempenho foram o Método Modificado das Tolerâncias Flexíveis com variáveis escalonadas (MFTMS) e o híbrido FTMS-PSO (o Método das Tolerância Flexíveis com escalonamento de variáveis e hibridizado com PSO). Estes melhores códigos foram aplicados com sucesso na solução de problemas de integração em massa. Os resultados encontrados neste trabalho demonstram a capacidade de métodos simples e diretos em lidar com problemas de otimização complexos, como os problemas de integração mássica. Além disso, um problema inédito de integração mássica proposto neste trabalho, a integração mássica de uma biorefinaria de cana-de-açúcar incluindo 1G, 2G e 3G, foi resolvido com êxito com os métodos propostos neste trabalho (MFTMS e FTMS-PSO). A primeira geração (1G) inclui a produção de etanol utilizando o caldo da cana-de-açúcar e produção de vapor e eletricidade pela cogeração. A segunda geração (2G) utiliza a biomassa lignocelulósica para produção de etanol pela rota bioquímica. A terceira geração (3G) inclui a utilização de algas para produção de biocombustíveis (etanol e biodiesel). Os resultados deste estudo de caso fornecem uma indicação de uma forma economicamente viável de conseguir avanços substanciais em termos de consumo de água e redução da poluição.
This work is focused in constrained nonlinear optimization using the Flexible Tolerance Method (FTM) and in applying in systems synthesis of mass integration. Mass integration is a technique that allows an overall understanding of the mass flow within the process, and employs such knowledge in identification of performance improvements and optimization of the generation and mapping of species throughout the process. The mass integration is based on the fundamental principles of chemical engineering combined with system analysis using graphical and optimization tools. In this context, the direct method of optimization was used as the basis for improvements in order to make possible the application in process synthesis problems, especially mass integration. The Flexible Tolerance Method is a direct method of optimization that present some advantages as simplicity, the ability to lead with equality and inequality constraints without employ derivative calculus. The method uses two searches to satisfy feasibility constraint. The external search is a variation of the Nelder-Mead method (or the Flexible Polyhedron method or FPM). This one seeks to minimizes the objective function. The internal search minimizes the value of the positive function for all equality and/or inequality constraints of the problem. This internal search can be performed by any unconstrained nonlinear optimization method. In this work, the Flexible Tolerance Method was hybridized with different unconstrained methods to perform the inner search: the BFGS (Broyden, Fletcher, Goldfarb and Shanno Method) and the modified Powell. The stochastic PSO method was also employed to perform the initialization and generation of the feasible start point to sequential application of the determination method i (FTM and modifications). Others modifications tested were the scaling of variables, the use of Nelder-Mead adaptive parameters and the addition of a barrier. The algorithms proposed in this work were applied to a benchmark of constrained nonlinear problems that comprises real world optimization problems. The best codes obtained were the Modified Flexible Tolerance Method Scaled (MFTMS) and the hybrid FTMS-PSO (the Flexible Tolerance Method with scaling of variables hybridized with PSO (Particle Swarm Optimization)). These best codes were applied with success in the solution of mass integration problems. The results found in this work demonstrate the capacity of simple and direct methods in deals with complex optimization problems, as the mass integration problems. Additionally an inedited problem of mass integration proposed in this work, the mass integration of 1G, 2G and 3G sugarcane biorefinery was successful solved with the methods proposed in this work (MFTMS and FTMS-PSO). The first generation (1G) includes the ethanol production using the sugarcane juice and production of vapor and electricity throughout cogeneration. The second generation (2G) includes the ethanol production using the lignocellulosic biomass feedstock via the biochemical route. The third generation (3G) includes the algae use for production of biofuels (ethanol and biodiesel). The findings of this study case provide an indication of an economically viable way of achieving substantial advances in terms of water consumption and pollution reduction.
Petruccioli, Andrea <1993>. "Development of a Computer-Based methodology for tolerance selection and optimization applied to the automotive sector." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10322/1/PhD%20Thesis%20Andrea%20Petruccioli.pdf.
Islam, Ziaul. "A design of experiment approach to tolerance allocation." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179428292.
Moneghan, Matthew John. "Microstructural Deformation Mechanisms and Optimization of Selectively Laser Melted 316L Steel." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/104170.
Master of Science
Many researchers have studied the impacts of laser parameters on the bulk material properties of SLM printed parts; few if any have studied how these parts break at a microstructural level. In this work we show how SLM printed parts with complex microstructures including grains, meltpools, and cells, deform and break. The cellular network that occurs in some SLM printed parts leads to a multi-material hierarchical structure, with a stiff network of thin boundaries, and a bulk "matrix" of soft cell material. This leads to similar properties as some composites, whereby the stiff network of cell boundaries leads to increased damage tolerance. We show both computationally through finite element analysis, and experimentally through multi-material 3D fabrication, that the microstructure leads to increased crack length in failure, as well as lower toughness loss and strength loss in the event of a crack. Essentially, the complex nature of the formation of these parts (high heating and cooling rates from laser melting) leads to a beneficial microstructure for damage tolerance that has not been studied from this perspective before.
Nielsen, Mark. "Design of aerospace laminates for multi-axis loading and damage tolerance." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760971.
Guenoun, Pierre S. M. Massachusetts Institute of Technology. "Design optimization of advanced PWR SiC/SiC fuel cladding for enhanced tolerance of loss of coolant conditions." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103649.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 64-68).
Limited data has been published (especially on experimental work) on integrated multilayer SiC/SiC prototypical fuel cladding. In this work the mechanical performance of three unique architectures of three-layer silicon carbide (SiC) composite cladding is experimentally investigated under conditions associated with the loss of coolant accident (LOCA), and analytically under various conditions. Specifically, this work investigates SiC cladding mechanical performance after exposure to 1,400°C steam for 48 hours and after thermal shock induced by quenching from 1,200°C into either 100°C or 90°C water. Mechanical performance characteristics are thereafter correlated with sample architecture through void characterization and ceramography. The series with a reduced thickness did not have a pseudo-ductile regime due to overloading of the composite layer. The presence of the axial tow did not yield significant difference in the mechanical behavior most likely because samples were tested in the hoop direction. While as-received and quenched samples behaved similarly (pseudo ductile failure except for one series), non-frangible brittle failure (single-crack failure with no release of debris) was systematically observed after oxidation due to silica buildup in the inner voids of the ceramic matrix composite (CMC) layer. Overall, thermal shock had limited influence on sample mechanical characteristics and oxidation resulted in the formation of silica on the inner wall of the CMC voids leading to the weakening of the monolith matrix and brittle fracture. Stress field in the cladding design is simulated by finite element analysis under service and shutdown conditions at both the core's middle height and at the end of the fuel rod. Stresses in the fuel region are driven by the thermal gradient that creates stresses predominantly from irradiation induced swelling. At the endplug, constraints are mainly mechanical. Stress calculations show high sensitivity to the data scatter and especially swelling and thermal conductivity. No cladding with the design studied here can survive either service or shutdown conditions because of the high irradiation-induced tensile stresses that develop in the hot inner monolith layer. It is shown that this peak tensile stress can be alleviated by adjusting the swelling level of the different layers. The addition of an under-swelling material such as PyC or Si can reduce the monolith tensile stress by 10%. With a composite that swells 10% less than the monolith, the stress is reduced by 20%.
by Pierre Guenoun.
S.M.
Pendse, Nachiket Vishwas. "An effective dimensional inspection method based on zone fitting." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3239.
Zhou, Yao. "Study on genetic algorithm improvement and application." Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050306-211907/.
Albandes, Iuri. "Use of Approximate Triple Modular Redundancy for Fault Tolerance in Digital Circuits." Doctoral thesis, Universidad de Alicante, 2018. http://hdl.handle.net/10045/88248.
Väyrynen, Mikael. "Fault-Tolerant Average Execution Time Optimization for General-Purpose Multi-Processor System-On-Chips." Thesis, Linköping University, Linköping University, Linköping University, Department of Computer and Information Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17705.
Fault tolerance is due to the semiconductor technology development important, not only for safety-critical systems but also for general-purpose (non-safety critical) systems. However, instead of guaranteeing that deadlines always are met, it is for general-purpose systems important to minimize the average execution time (AET) while ensuring fault tolerance. For a given job and a soft (transient) no-error probability, we define mathematical formulas for AET using voting (active replication), rollback-recovery with checkpointing (RRC) and a combination of these (CRV) where bus communication overhead is included. And, for a given multi-processor system-on-chip (MPSoC), we define integer linear programming (ILP) models that minimize the AET including bus communication overhead when: (1) selecting the number of checkpoints when using RRC or a combination where RRC is included, (2) finding the number of processors and job-to-processor assignment when using voting or a combination where voting is used, and (3) defining fault tolerance scheme (voting, RRC or CRV) per job and defining its usage for each job. Experiments demonstrate significant savings in AET.
Keresztes, Janos C., Koshel R. John, Karlien D’huys, Ketelaere Bart De, Jan Audenaert, Peter Goos, and Wouter Saeys. "Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design." OPTICAL SOC AMER, 2016. http://hdl.handle.net/10150/622951.
Shrimal, Shubhendra. "Maximizing Parallelization Opportunities by Automatically Inferring Optimal Container Memory for Asymmetrical Map Tasks." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1468011920.
Samii, Soheil. "Quality-Driven Synthesis and Optimization of Embedded Control Systems." Doctoral thesis, Linköpings universitet, Institutionen för datavetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68641.
Lee, Abraham. "A Hybrid Method for Sensitivity Optimization With Application to Radio-Frequency Product Design." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4358.
Sebaey, Abdella Tamer Ali Abdella. "Characterization and optimization of dispersed composite laminates for damage resistant aeronautical structures." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/98393.
El principal objectiu de la tesi és valorar la resistència al dany i la tolerància al dany dels laminats no-convencionals dispersos i comparar la seva resposta amb la dels laminats convencionals. No obstant, part de l'atenció es dedica a comprendre el comportament de la delaminació en laminats multidireccionals. En la primera part de la tesi, s'analitza la delaminació en laminats multidireccionals. L'objectiu és dissenyar una seqüència d'apilament apropiada per evitar el dany intralaminar (migració de la delaminació) i permetre la caracterització de la tenacitat a la fractura en model. Els resultats d'aquests estudi mostren que a major rigidesa a flexió dels braços de l'esquerda, menor és la tendència a la migració de l'esquerda. Aquest aspecte també s'ha analitzat experimentalment, obtenint les mateixes conclusions.
Martin, Ivo [Verfasser], Dieter [Gutachter] Bestle, and Arnold [Gutachter] Kühhorn. "Automated process for robust airfoil design-optimization incorporating critical eigenmode identification and production-tolerance evaluation / Ivo Martin ; Gutachter: Dieter Bestle, Arnold Kühhorn." Cottbus : BTU Cottbus - Senftenberg, 2019. http://d-nb.info/1180389603/34.
Psiakis, Rafail. "Performance optimization mechanisms for fault-resilient VLIW processors." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S095/document.
Embedded processors in critical domains require a combination of reliability, performance and low energy consumption. Very Long Instruction Word (VLIW) processors provide performance improvements through Instruction Level Parallelism (ILP) exploitation, while keeping cost and power in low levels. Since the ILP is highly application dependent, the processor does not use all its resources constantly and, thus, these resources can be utilized for redundant instruction execution. This thesis presents a fault injection methodology for VLIW processors and three hardware mechanisms to deal with soft, permanent and long-term faults leading to three contributions. The first contribution presents an Architectural Vulnerability Factor (AVF) and Instruction Vulnerability Factor (IVF) analysis schema for VLIW processors. A fault injection methodology at different memory structures is proposed to extract the architectural/instruction masking capabilities of the processor. A high-level failure classification schema is presented to categorize the output of the processor. The second contribution explores heterogeneous idle resources at run-time both inside and across consecutive instruction bundles. To achieve this, a hardware optimized instruction scheduling technique is applied in parallel with the pipeline to efficiently control the replication and the scheduling of the instructions. Following the trends of increasing parallelization, a cluster-based design is also proposed to tackle the issues of scalability, while maintaining a reasonable area/power overhead. The proposed technique achieves a speed-up of 43.68% in performance with a ~10% area and power overhead over existing approaches. AVF and IVF analysis evaluate the vulnerability of the processor with the proposed mechanism.The third contribution deals with persistent faults. A hardware mechanism is proposed which replicates at run-time the instructions and schedules them at the idle slots considering the resource constraints. If a resource becomes faulty, the proposed approach efficiently rebinds both the original and replicated instructions during execution. Early evaluation performance results show up to 49\% performance gain over existing techniques.In order to further decrease the performance overhead and to support single and multiple Long-Duration Transient (LDT) error mitigation a fourth contribution is presented. We propose a hardware mechanism, which detects the faults that are still active during execution and re-schedules the instructions to use not only the healthy function units, but also the fault-free components of the affected function units. When the fault faints, the affected function unit components can be reused. The scheduling window of the proposed mechanism is two instruction bundles being able to explore mitigation solutions in the current and the next instruction execution. The obtained fault injection results show that the proposed approach can mitigate a large number of faults with low performance, area, and power overhead
Zheng, Yexin. "Circuit Design Methods with Emerging Nanotechnologies." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/30000.
Ph. D.
Rau, Anand V. "Processing of toughened cyanate ester matrix composites." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151604/.
García, Gómez Sonia C. "Allocation et optimisation de tolérances géométriques par des polyédres prismatiques." Electronic Thesis or Diss., Bordeaux, 2023. http://www.theses.fr/2023BORD0504.
Geometric and dimensional deviations of mechanical components can cause problems of assemblability and/or functionality of the mechanisms. The geometric and dimensional specifications represent the limits of the manufacturing defects of a given surface. Tolerance specification is not an easy task because (i) the assigned tolerance values affect the functionalities of a system and the manufacturing cost of its parts, and (ii) design tolerances are often interrelated and contribute to a resultant tolerance.Tolerance analysis and tolerance synthesis are the two typical ways to approach the problem of tolerance design. Tolerance synthesis is traditionally seen as a "constrained optimization problem" in which the objective function is usually a cost function, a quality function or a cost-quality.In the case of over-constrained mechanisms, the interaction of the tolerances is complex and it is not possible to describe it by means of an analytical function. Hence, it is typical to do tolerance allocation instead of tolerance synthesis. The objective of the tolerance allocation is then to complete or augment the tolerance specification, originally made from experience or empirical knowledge, by incorporating some heuristics or optimization methods.In this work we show how to do tolerance allocation using the prismatic polyhedral approach as tolerance model and the simulated annealing as the heuristic optimization algorithm. In order to do this, some intermediate problems are discussed, such us (i) quality of the operands, (ii) computational time required to do a simulation and we also develop (iii) an indicator to quantify the compliance of a mechanism with its functional condition
Guilbert, Damien. "Tolérance aux défauts et optimisation des convertisseurs DC/DC pour véhicules électriques à pile à combustible." Thesis, Belfort-Montbéliard, 2014. http://www.theses.fr/2014BELF0245/document.
Over the last years, reliability and continuity of service of powertrains have become major challenge so that the fuel cell electric vehicles (CFEV) can access to the mass automotive market. Indeed, the presence of faults in powertrains can lead up to malfunctions in the vehicle and consequently reduce its performances compared with conventional vehicles. In the case of electrical faults, powertrains of FCEV have to include fault tolerant topology and/or control for the different DC/DC and DC/AC converters. Within the framework of this research work, the study is focused on DC/DC converter combined with a Proton Exchange Membrane Fuel Cell (PEMFC). The DC/DC converter must respond to challenging issues in FCEV applications such as: low weight and small volume, high energy efficiency, fuel cell current ripple reduction and reliability. Basing on a thorough bibliographical study on non-isolated and isolated DC/DC converter topologies, an interleaved DC/DC boost converter has been chosen, meeting the FCEV requirements.The purpose of this thesis has then consisted in sizing and controlling the chosen fault-tolerant DC/DC converter topology for FCEVs. Algorithms for degraded mode management of this converter have been developed and implemented experimentally. As such, the interaction between PEMFC and interleaved DC/DC boost converter has been investigated. A theoretical approach, simulation and experimental results have been carried out to complete this work
Goka, Edoh. "Analyse des tolérances des systèmes complexes – Modélisation des imperfections de fabrication pour une analyse réaliste et robuste du comportement des systèmes." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0019/document.
Tolerance analysis aims toward the verification of the impact of individual tolerances on the assembly and functional requirements of a mechanical system. The manufactured products have several types of contacts and their geometry is imperfect, which may lead to non-functioning and non-assembly. Traditional methods for tolerance analysis do not consider the form defects. This thesis aims to propose a new procedure for tolerance analysis which considers the form defects and the different types of contact in its geometrical behavior modeling. A method is firstly proposed to model the form defects to make realistic analysis. Thereafter, form defects are integrated in the geometrical behavior modeling of a mechanical system and by considering also the different types of contacts. Indeed, these different contacts behave differently once the imperfections are considered. The Monte Carlo simulation coupled with an optimization technique is chosen as the method to perform the tolerance analysis. Nonetheless, this method is subject to excessive numerical efforts. To overcome this problem, probabilistic models using the Kernel Density Estimation method are proposed
Кудряшов, В. С. "Удосконалення технологічного процесу виготовлення шестерні 1412.1820.1334 редуктора Ц2У-100 шляхом структурно-параметричної оптимізації зубофрезерної операції". Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/81973.
The master's qualification work is 104 pages, including twenty figures, twenty tables, bibliographies from 23 sources, 11 appendices on 26 pages. The purpose of the work. Improving the efficiency of the technological process of manufacturing "gears" by structural and parametric optimization of gear milling operation. To solve this goal in the work were set and solved the following tasks: 1) perform an analysis of the basic technological process of manufacturing parts; 2) to develop a promising technological process of manufacturing parts; 3) to design a special design of the device for milling teeth; 4) to design a special design of the control and measuring device for control of radial and face beating of surfaces of a detail; 5) perform research of the designed design of the machine tool by methods of static and dynamic analysis. Formulate recommendations for improving the design of the machine tool. The object of research is the technological process of making "gears", gear milling operation. The subject of research - structural and parametric optimization of gear milling operation, design of devices for milling teeth. Scientific novelty: as a result of theoretical and experimental researches the static and dynamic analysis of the offered design of the device for milling of teeth of "gear wheel" that allowed to formulate the offers and recommendations directed on improvement of a design, maintenance of its steady work and increase of efficiency of tooth milling operation as a whole.
Tierno, Antonio. "Automatic Design Space Exploration of Fault-tolerant Embedded Systems Architectures." Doctoral thesis, Università degli studi di Trento, 2023. https://hdl.handle.net/11572/364571.
Hays, Joseph T. "Parametric Optimal Design Of Uncertain Dynamical Systems." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28850.
Ph. D.
Mitropoulou, Konstantina. "Performance optimizations for compiler-based error detection." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10473.
Dumas, Antoine. "Développement de méthodes probabilistes pour l'analyse des tolérances des systèmes mécaniques sur-contraints." Thesis, Paris, ENSAM, 2014. http://www.theses.fr/2014ENAM0054/document.
Tolerance analysis of mechanism aims at evaluating product quality during its design stage. Technique consists in computing a defect probability of mechanisms in large series production. An assembly condition and a functional condition are checked. Current method mixes a Monte Carlo simulation and an optimization algorithm which is too much time consuming. The objective of this thesis is to develop new efficient method based on probabilistic approach to deal with the tolerance analysis of overconstrained mechanism. First, a linearization procedure is proposed to simplify the optimization algorithm step. The impact of such a procedure on the probability accuracy is studied. To overcome this issue, iterative procedures are proposed to deal with the assembly problem. They enable to compute accurate defect probabilities in a reduced computing time. Besides, a new resolution method based on the system reliability method FORM (First Order Reliability Method) for systems was developed for the functional problem. In order to apply this method, a new system formulation of the tolerance analysis problem is elaborated. Formulation splits up the overconstrained mechanism into several isoconstrained configurations. The goal is to consider only the main configurations which lead to a failure situation. The proposed method greatly reduces the computing time allowing getting result within minutes. Low probabilities can also be reached and the order of magnitude does not influence the computing time
Nilsson, Johan. "Accurate description of heterogeneous tumors for biologically optimized radiation therapy." Doctoral thesis, Stockholm : Division of medical radiation physics, Department of oncology-pathology, Stockholm University and Karolinska Institutet, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-311.
Benichou, Sami. "Intégration des effets des dilatations thermiques dans le tolérancement." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00749566.
Thakral, Garima. "Process-Voltage-Temperature Aware Nanoscale Circuit Optimization." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc67943/.
Izosimov, Viacheslav. "Scheduling and optimization of fault-tolerant distributed embedded systems." Doctoral thesis, Linköping : Department of Computer and Information Science, Linköping University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-51727.
Umaras, Eduardo. "Tolerâncias dimensionais em conjuntos mecânicos: estudo e proposta para otimização." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-20102010-153205/.
This work approaches the concepts needed to the study of dimensional tolerances of a mechanical assembly and proposes an effective method for specifying tolerances in the detailing phase of product design, by means of an optimization algorithm based on manufacturing costs. Concepts of quality loss developed by Genichi Taguchi are also applied for specifying functional constraints, which aim to assure an adequate quality level regarding specified values of functional criteria. Comments and comparisons with other dimensional tolerances optimization works are also made, through which specific features of the proposed method can be observed. An application example of the method is presented through a case study based on a belt power transmission system to ancillary equipment of an internal combustion engine. Results of application of the optimization algorithm are compared with the ones of conventional tolerance synthesis methods, showing their effectiveness.
Schott, Jason R. (Jason Ramon). "Fault tolerant design using single and multicriteria genetic algorithm optimization." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11582.
Panhalkar, Neeraj. "Hierarchical Data Structures for Optimization of Additive Manufacturing Processes." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310812.
Pollet, Félix. "Conception optimale de drones électriques : une approche multidisciplinaire avec analyse des incertitudes, de la tolérance aux pannes et des impacts environnementaux." Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0013.
Unmanned aerial vehicles (UAVs) have undergone intensive development in recent years. Owing to their cost-effectiveness and versatility, UAVs are expected to gain popularity in a wide range of applications, such as parcel delivery, power line monitoring and precision farming. Concurrently, the development of new technologies and their integration into various drone concepts is expanding the range of design alternatives. This is driving the need for holistic design approaches with better technology integration, faster development time and greater modularity.The thesis develops and implements a methodology for the conceptual design of electric multirotor, fixed-wing and hybrid vertical take-off and landing (VTOL) UAVs. The framework enables the optimal sizing of a UAV from arbitrary specifications on the mission, technological choices and architecture, using a comprehensive multidisciplinary approach.Starting from a set of analytical models including scaling laws and regressions, a generic sizing methodology is developed. The proposed methodology relies on an efficient multidisciplinary design and optimization (MDO) formulation, which enables fast convergence to the UAV candidate with best performances. In particular, the application of this approach enables to rapidly assess the effects of changes in the requirements. Next, the uncertainties surrounding the models and the availability of optimal components on the market are assessed. To mitigate critical uncertainties in UAV performance, the sizing methodology is extended to allow the design to be optimized using catalogues of existing components instead of models. Finally, the thesis develops two specific aspects of UAV design related to regulatory and societal challenges. On the one hand, recent regulations issued by the European Union Aviation Safety Agency (EASA) impose a level of safety for specific categories of UAVs. To this end, an approach is proposed to assess the controllability of various architectures in the event of failures. The assessment is further linked to the design framework to achieve fault-tolerance sizing of the rotors and control surfaces. On the other hand, societal acceptance of UAVs is strongly related to environmental concerns, including but not limited to climate change and resource consumption. This challenge is addressed by developing and integrating an environmental discipline into the design framework. The novel approach enables to assess the sensitivity of environmental impacts to mission requirements and technological assumptions, as well as minimizing environmental burdens at the earliest design stages.The thesis contributes to the development of a unified framework for optimizing the design of electric UAVs with a holistic approach. As such, it is relevant to future UAVs designed for applications subject to market, regulatory and environmental issues
Sheldon, Karl Edward. "Analysis Methods to Control Performance Variability and Costs in Turbine Engine Manufacturing." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32290.
Master of Science
Hiscox, Briana (Briana Diane). "Analysis and optimization of a new accident tolerant fuel called fuel-in-fibers." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119046.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 64-68).
The 2011 Fukushima Daiichi accident highlighted the weakness of the current nuclear fuel and motivated R&D of accident tolerant fuels. Accident tolerant fuels (ATF) are fuels that can tolerate loss of active cooling in the core of light water reactors (LWRs) for a considerably longer period of time while maintaining or improving the fuel performance during normal operations. Fully Ceramic Microencapsulated (FCM) fuel is an ATF concept aimed at significantly increasing the fission product retention capability of nuclear fuel at high temperatures. The FCM concept is made up of fuel particles surrounded by multilayers of ceramic material similar to the TRISO fuel concept. The fuel particles are embedded in a SiC matrix in cylindrical pellet geometry which gives the fuel its high temperature corrosion resistance. However, when implementing the FCM concept in a conventional PWR fuel geometry, it is not possible to maintain an 18 month fuel cycle length and remain below the proliferation enrichment limit of 20 w/o U₂₃₅. This is a critical challenge that needs to be overcome in order to benefit from the high temperature fission product retention capability of FCM-type ATF concepts. Therefore, this work aims at investigating the potential benefits of a new accident tolerant fuel, Fuel-in-Fibers (F-in-F) concept. The Fuel-in-Fibers concept was created by Free Form Fibers, a laser chemical vapor deposition direct manufacturing company. It aims to combine the same robust fission product retention and high temperature stability as the FCM fuel concept while drastically decreasing the necessary fuel enrichment. This is done by designing a fuel fiber in cylindrical geometry as opposed to spherical particles to increase the packing fraction within a cylindrical pellet. The direct manufacturing allows for minimization of the volume occupied by the SiC matrix as well as direct deposition of high density fuels like uranium nitride (UN). Assembly level calculations in the Monte Carlo code SERPENT determined that the Fuel-in-Fibers concept could maintain a typical PWR cycle length with less than 20 w/o U₂₃₅ (LEU) enrichment. The fibers in the fuel pellet were then homogenized for use in lattice physics code CASMO and core simulator code SIMULATE3. The SIMUALTE full core simulation showed that the Fuel-in- Fibers design required enrichments of 8% and 6% for UO2 and UN as fuels, respectively. Overall, the full core analysis of a standard 4-loop Westinghouse PWR showed Fuel-in-Fibers concept has similar behavior as the conventional fuel. Due to the high fissile enrichments, the calculated radial power peaking factors were higher in Fuel-in-Fibers concept. This may result in decrease of the coolant outlet temperature by 5 K in order to maintain safety margins. The shutdown margin analysis showed that using B4C instead AgInCd control rods is needed. A design optimization was also performed to calculate the ideal geometry for Fuel-in-Fibers concept. An in-house MATLAB single channel code, built to evaluate PWR Thermal Hydraulic and Structural performance, was used to vary the fuel pin Pitch and Pitch-to-Diameter ratio (P/D Ratio). The results showed that a smaller pitch and larger diameter of 13.2 mm and 12 mm, respectively will improve the Fuel-in-Fibers concept enrichment requirements. A simplified economic analysis based on highly uncertain fabrication cost estimates was performed. The economics analysis determined that the fuel in fiber design is estimated to cost more than current UO₂ fuel by 1.25x - 15x due to the increased enrichment and fabrication costs but may be offset by the additional safety margins provided by the Fuel-in-Fibers concept.
by Briana Hiscox.
S.M.