Дисертації з теми "Physical-statistical model of reliability"
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Kim, Seong W. "Bayesian model selection using intrinsic priors for commonly used models in reliability and survival analysis /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841159.
Повний текст джерелаBrownstein, Naomi. "Estimation and the Stress-Strength Model." Honors in the Major Thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1160.
Повний текст джерелаBachelors
Sciences
Mathematics
Bakouros, Y. L. "Offshore pipeline reliability prediction : An assessment of the breakdown characteristics of offshore pipelines and the development of a statistical technique to improve their reliability prediction with particular reference." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233657.
Повний текст джерелаMoberg, Pontus, and Filip Svensson. "Cost Optimisation through Statistical Quality Control : A case study on the plastic industry." Thesis, Blekinge Tekniska Högskola, Institutionen för industriell ekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21922.
Повний текст джерелаMatthews, Robert. "The Reliability and Validity of a Simulated Airway Model that Quantifies Physical Forces Exerted During Endotracheal Intubation in a Clinically Demanding Scenario." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/2466.
Повний текст джерела林達明 and Daming Lin. "Reliability growth models and reliability acceptance sampling plans from a Bayesian viewpoint." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B3123429X.
Повний текст джерелаCarstens, Wiehahn Alwyn. "Regression analysis of caterpillar 793D haul truck engine failure data and through-life diagnostic information using the proportional hazards model." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20333.
Повний текст джерелаENGLISH ABSTRACT: Physical Asset Management (PAM) is becoming a greater concern for companies in industry today. The widely accepted British Standards Institutes’ specification for optimized management of physical assets and infrastructure is PAS55. According to PAS55, PAM is the “systematic and co-ordinated activities and practices through which an organization optimally manages its physical assets, and their associated performance, risks and expenditures over their life cycle for the purpose of achieving its organizational strategic plan”. One key performance area of PAM is Asset Care Plans (ACP). These plans are maintenance strategies which improve or ensure acceptable asset reliability and performance during its useful life. Maintenance strategies such as Condition Based Maintenance (CBM) acts upon Condition Monitoring (CM) data, disregarding the previous failure histories of an asset. Other maintenance strategies, such as Usage Based Maintenance (UBM), is based on previous failure histories, and does not consider CM data. Regression models make use of both CM data and previous failure histories to develop a model which represents the underlying failure behaviour of the asset under study. These models can be of high value in ACP development due to the fact that Residual Useful Life (RUL) can be estimated and/or the long term life cycle cost can be optimized. The objective of this thesis was to model historical failure data and CM data well enough so that RUL or optimized preventive maintenance instant estimations can be made. These estimates were used in decision models to develop maintenance schedules, i.e. ACPs. Several regression models were evaluated to determine the most suitable model to achieve the objectives of this thesis. The model found to be most suitable for this research project was the Proportional Hazards Model (PHM). A comprehensive investigation on the PHM was undertaken focussing on the mathematics and the practical implementation thereof. Data obtained from the South African mining industry was modelled with the Weibull PHM. It was found that the developed model produced estimates which were accurate representations of reality. These findings provide an exciting basis for the development of futureWeibull PHMs that could result in huge maintenance cost savings and reduced failure occurrences.
AFRIKAANSE OPSOMMING: Fisiese Bate Bestuur (FBB) is besig om ’n groter bekommernis vir maatskappye in die bedryf te word. Die Britse Standaarde Instituut se spesifikasie vir optimale bestuur van fisiese bates en infrastruktuur is PAS55. Volgens PAS55 is FBB die “sistematiese en gekoördineerde aktiwiteite en praktyke wat deur ’n organisasie optimaal sy fisiese bates, hul verwante prestasie, risiko’s en uitgawes vir die doel van die bereiking van sy organisatoriese strategiese plan beheer oor hul volle lewensiklus te bestuur”. Een Sleutel Fokus Area (SFA) van FBB is Bate Versorgings Plan (BVP) ontwikkeling. Hierdie is onderhouds strategieë wat bate betroubaarheid verbeter of verseker tydens die volle bruikbare lewe van die bate. Een onderhoud strategie is Toestands Gebasseeerde Onderhoud (TGO) wat besluite baseer op Toestand Monitering (TM) informasie maar neem nie die vorige falingsgeskiedenis van die bate in ag nie. Ander onderhoud strategieë soos Gebruik Gebasseerde Onderhoud (GGO) is gebaseer op historiese falingsdata maar neem nie TM inligting in ag nie. Regressiemodelle neem beide TM data en historiese falings geskiedenis data in ag ten einde die onderliggende falings gedrag van die gegewe bate te verteenwoordig. Hierdie modelle kan baie nuttig wees vir BVP ontwikkeling te danke aan die feit dat Bruikbare Oorblywende Lewe (BOL) geskat kan word en/of die langtermyn lewenssilus koste geoptimeer kan word. Die doelwit van hierdie tesis was om historiese falingsdata en TT data goed genoeg te modelleer sodat BOL of optimale langtermyn lewensiklus kostes bepaal kan word om opgeneem te word in BVP ontwikkeling. Hierdie bepalings word dan gebruik in besluitnemings modelle wat gebruik kan word om onderhoud skedules op te stel, d.w.s. om ’n BVP te ontwikkel. Verskeie regressiemodelle was geëvalueer om die regte model te vind waarmee die doel van hierdie tesis te bereik kan word. Die mees geskikte model vir die navorsingsprojek was die Proporsionele Gevaarkoers Model (PGM). ’n Omvattende ondersoek oor die PGM is onderneem wat fokus op die wiskunde en die praktiese implementering daarvan. Data is van die Suid-Afrikaanse mynbedryf verkry en is gemodelleer met behulp van die Weibull PGM. Dit was bevind dat die ontwikkelde model resultate geproduseer het wat ’n akkurate verteenwoordinging van realiteit is. Hierdie bevindinge bied ’n opwindende basis vir die ontwikkeling van toekomstige Weibull Proporsionele Gevaarkoers Modelle wat kan lei tot groot onderhoudskoste besparings en minder onverwagte falings.
Lin, Daming. "Reliability growth models and reliability acceptance sampling plans from a Bayesian viewpoint /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13999618.
Повний текст джерелаFreeman, Laura J. "Statistical Methods for Reliability Data from Designed Experiments." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37729.
Повний текст джерелаPh. D.
Jiang, Siyuan. "Mixed Weibull distributions in reliability engineering: Statistical models for the lifetime of units with multiple modes of failure." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185481.
Повний текст джерелаRomero, Alfredo A. "Statistical Adequacy and Reliability of Inference in Regression-like Models." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27782.
Повний текст джерелаPh. D.
Михайлів, Ярослав Андрійович. "Аналіз достовірності вихідної інформації, розрахункових моделей та методів оцінки надійності розподільних мереж". Master's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/35759.
Повний текст джерелаActuality of theme. The problem of reliable supply of electricity to consumers is one of the most important in solving the problems of designing and operating power systems (EPS) of cities, industrial enterprises and individual objects. Requirements for reliable electricity supply are defined by the relevant regulatory documents and must be clearly considered and implemented. Both consumers and businesses are seriously harmed by forced power outages. At any level of electricity infrastructure, ensuring the reliability of electricity supply to consumers has always been an important scientific and technical problem, the research and solution of which is devoted to the numerous works of scientists and research and design organizations (KPI, TSU, MEI, etc.). Main directions of research: obtaining, systematization and processing of statistical information, evaluation of its reliability; development of adequate calculation models for evaluation and optimization of reliability of elements, circuits and power supply system as a whole; determination of effective systemic reliability indicators and methods of their calculation and making optimal decisions; economic indicators of losses of consumers and power supply organizations from under-receipt and under-release of electricity. General analysis of the operation of electrical networks at the moment shows that their technical condition is unsatisfactory, there is an aging equipment, progressing, and, consequently, a decrease in the reliability of the elements and power systems. Moreover, the constant complexity of the structure and the emergence of new network elements requires the development of a theory of solving the problems of estimating and improving the reliability of energy supply. Accordingly, there is a need to develop a decision-making methodology at the stages of construction, reconstruction and operation of distribution grids (DG). In assessing the reliability of consumer electricity systems, such indicators as the probability of an accidental event of a power outage, the accidental magnitude of unavailability of electricity to consumers (which occurred as a result of events that have occurred or are predicted, calculated) are usually considered, real or projected losses of consumers or electricity supply organization. The analysis shows that the damage rates of the elements of distribution networks and the value of losses borne by consumers almost always depend on the specific conditions. Moreover, even for the same operating conditions, fluctuations in the integrity indicators of network elements are occasionally fluctuated, by more than 100 percent. This indicates that in the conditions of each system it is necessary to analyze the data of the accident statistics with the determination of the real factors of influence on the original design indicators (lengths of lines, circuit decisions, number of nodes, etc.) It should also be considered and taken into account when determining the losses (which occurred or projected) their essential dependence on the season, time of day, and also - to a large extent - on how long the break in the power supply of the consumer. The analysis of statistical information indicates a significant instability, non-stationarity of indicators used in the formation of calculation models, evaluation of the reliability of schemes. The systematic approach to developing more efficient models and methods of assessing the reliability of distribution networks is more relevant than ever. The purpose and tasks of the study. The purpose of the work is to develop a methodology for evaluating the reliability of the original parameters of the reliability of the SEM, which are determined by the limited amount of data of the accident statistics, and the influence of the adopted calculation models on the results of calculating the network reliability indicators. Research objectives: analysis of information on the functioning of distribution electric networks; assessment of reliability of baseline reliability indicators, determination and consideration of influential factors, laws of distribution of random variables; selection and comparison of calculation models of reliability estimation of distribution electric networks with voltage of 6-10 kV on the basis of processing of received data of emergency statistics; sequence of implementation of the systematic approach to statistical analysis information and assessing the reliability of electricity supply. Object of research - Distribution networks of power supply systems of cities. Subject of research - Mathematical models, methods for assessing the reliability of power supply systems, taking into account the peculiarities of operating conditions and the amount of received information. Research methods. The basis of the performed research was the following methods: nonlinear programming - a method of discrete coordinate descent for making decisions on the optimization of network breakpoints; probability theory - is used to estimate the effect of initial information errors on the accuracy of determining power losses and the value of the probable non-release of electricity to consumers when calculating reliability indicators; mathematical statistics - for plotting distribution histograms according to emergency statistics, as well as determining distribution laws and their parameters; to describe the curves showing the dependence of a possible error in the calculation of values on the volume of statistics relating to reliability indicators; statistical test method (Monte Carlo) - to determine the impact of errors of initial information on decision making, while minimizing the lack of electricity to consumers. Elements of scientific novelty of the obtained results. 1. A comprehensive approach was implemented in addressing the issues of estimation of source information errors and their impact on the calculation models, namely reliability. 2. A methodology for estimating the impact of the reliability of the source information on the value of the calculated reliability indicators of the distribution networks when using measures and methods of refining the indicators that are determined is proposed. 3. Smoothing of statistical distributions of data of emergency statistics and comparative analysis of calculation models taking into account individual factors is carried out. 4. The influence of the adopted calculation models on the results of the optimization of the modes of distribution networks is estimated, based on the minimization of power losses and taking into account the reliability of providing consumers with electricity. The practical value of the results. In the master's thesis the scientific results are obtained that are of value for the enterprises of electric networks in the issues of collection, systematization of information for its further processing in order to obtain the parameters of the calculation models. This significantly increases the reliability of the source information, the calculation models, as well as directly calculating the reliability of distribution networks.
McKinnon, Mika. "Landslide runout: statistical analysis of physical characteristics and model parameters." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25835.
Повний текст джерелаМазурок, Наталия Степановна. "Физико-статистический метод определения надежности изделий твердотельной электроники". Doctoral thesis, Киев, 2013. https://ela.kpi.ua/handle/123456789/6457.
Повний текст джерелаBilisoly, Roger. "Estimating mesoscale ocean currents from drifter trajectories using a spatiotemporal Bayesian statistical model /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949836205445.
Повний текст джерелаSuzuki, Satoshi. "The Development of Embedded DRAM Statistical Quality Models at Test and Use Conditions." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/341.
Повний текст джерелаRydén, Patrik. "Statistical analysis and simulation methods related to load-sharing models." Doctoral thesis, Umeå universitet, Matematisk statistik, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-46772.
Повний текст джерелаWang, Ni. "Statistical Learning in Logistics and Manufacturing Systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11457.
Повний текст джерелаMasiulaitytė, Inga. "Regression and degradation models in reliability theory and survival analysis." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100527_134956-15325.
Повний текст джерелаDaktaro disertacijos tyrimo objektai yra rezervuotos sistemos ir degradaciniai modeliai. Norint užtikrinti svarbių sistemos elementų aukštą patikimumą, naudojami jų rezerviniai elementai, kurie gali būti įjungiami sugedus šiems pagrindiniams elementams. Rezerviniai elementai gali funkcionuoti skirtinguose režimuose: „karštame“, „šaltame“ arba „šiltame“. Disertacijoje yra nagrinėjamos sistemos su „šiltai“ rezervuotais elementais. Darbe suformuluojama rezervinio elemento „sklandaus įjungimo“ hipotezė ir konstruojami statistiniai kriterijai šiai hipotezei tikrinti. Nagrinėjami neparametrinio ir parametrinio taškinio bei intervalinio vertinimo uždaviniai. Disertacijoje nagrinėjami pakankamai bendri degradacijos modeliai, kurie aprašo elementų gedimų intensyvumą kaip funkciją kiek naudojamų apkrovų, tiek ir degradacijos lygio, kuri savo ruožtu modeliuojama naudojant stochastinius procesus.
Cooper, Stephen-Mark. "Statistical methods for resolving issues relevant to test and measurement reliability and validity in variables related to sport performance and physical fitness." Thesis, Cardiff Metropolitan University, 2006. http://hdl.handle.net/10369/7393.
Повний текст джерелаKurtar, Ahmet Kursat. "Uncertainty Models For Vector Based Functional Curves And Assessing The Reliability Of G-band." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12608054/index.pdf.
Повний текст джерелаs epsilon band model, which is the most frequently used band model among the others. The tests are realized with two cases, testing with digitized lines by people and testing with randomly created lines with gaussian random number generator algorithm. So, the results can be examined in two different ways. The second aim of this thesis is development of band models for functional special curves. These functional curves are based on some mathematical models. Specifications of these curves are defined in the structure of Geographic Markup Language (GML) of Open GIS Consortium (OGC). They are arc, arc string, clothoid and cubic spline. Uncertainty for arc by three coordinates, arc string and cubic spline are modelled by G-Band. Arc by center point and clothoid are modelled by epsilon band. In this thesis, a commercial GIS API, GeoKIT is used to create the band geometries of functional curves, to perform some simulations and tests to make the comparison and to present the developed functionality as a desktop application. Band geomeiv tries are developed in the structure of API model which enable the functionality. Secondly, Matlab 2006a is used for technical computing to calculate multivariate normal cumulative density function (mvncdf) to be used in analyses and simulations.
Zhang, Xi. "Physical and statistical analysis of functional process variables for process control in semiconductor manufacturing." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003176.
Повний текст джерелаTobón, Gómez Catalina. "Three-dimensional statistical shape models for multimodal cardiac image analysis." Doctoral thesis, Universitat Pompeu Fabra, 2011. http://hdl.handle.net/10803/37473.
Повний текст джерелаCardiovascular diseases (CVDs) are the major cause of death in the Western world. The desire to prevent and treat CVDs has triggered a rapid development of medical imaging systems. As a consequence, the amount of imaging data collected in health care institutions has increased considerably. This fact has raised the need for automated analysis tools to support diagnosis with reliable and reproducible image interpretation. The interpretation task requires to translate raw imaging data into quantitative parameters, which are considered relevant to classify the patient’s cardiac condition. To achieve this task, statistical shape model approaches have found favoritism given the 3D (or 3D+t) nature of cardiovascular imaging datasets. By deforming the statistical shape model to image data from a patient, the heart can be analyzed in a more holistic way. Currently, the field of cardiovascular imaging is constituted by different modalities. Each modality exploits distinct physical phenomena, which allows us to observe the cardiac organ from different angles. Clinicians collect all these pieces of information to form an integrated mental model. The mental model includes anatomical and functional information to display a full picture of the patient’s heart. It is highly desirable to transform this mental model into a computational model able to integrate the information in a comprehensive manner. Generating such a model is not simply a visualization challenge. It requires having a methodology able to extract relevant quantitative parameters by applying the same principle. This assures that the measurements are directly comparable. Such a methodology should be able to: 1) accurately segment the cardiac cavities from multimodal datasets, 2) provide a unified frame of reference to integrate multiple information sources, and 3) aid the classification of a patient’s cardiac condition. This thesis builds upon the idea that statistical shape models, in particular Active Shape Models, are a robust and accurate approach with the potential to incorporate all these requirements. In order to handle multiple image modalities, we separate the statistical shape information from the appearance information. We obtain the statistical shape information from a high resolution modality and include the appearance information by simulating the physics of acquisition of other modalities. The contributions of this thesis can be summarized as: 1) a generic method to automatically construct intensity models for Active Shape Models based on simulating the physics of acquisition of the given imaging modality, 2) the first extension of a Magnetic Resonance Imaging (MRI) simulator tailored to produce realistic cardiac images, and 3) a novel automatic intensity model and reliability training strategy applied to cardiac MRI studies. Each of these contributions represents an article published or submitted to a peer-review archival journal.
Yajima, Ayako. "Assessment of Soil Corrosion in Underground Pipelines via Statistical Inference." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1435602696.
Повний текст джерелаMOMESSO, ROBERTA G. R. A. P. "Desenvolvimento e validação de um referencial metodológico para avaliação da cultura de segurança de organizações nucleares." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28035.
Повний текст джерелаMade available in DSpace on 2017-11-22T16:34:17Z (GMT). No. of bitstreams: 0
A cultura de segurança na área nuclear é definida como o conjunto de características e atitudes da organização e dos indivíduos que fazem que, com uma prioridade insuperável, as questões relacionadas à proteção e segurança nuclear recebam a atenção assegurada pelo seu significado. Até o momento, não existem instrumentos validados que permitam avaliar a cultura de segurança na área nuclear. Em vista disso, os resultados da definição de estratégias para o seu fortalecimento e o acompanhamento do desempenho das ações de melhorias tornam-se difíceis de serem avaliados. Este trabalho teve como objetivo principal desenvolver e validar um instrumento para a avaliação da cultura de segurança de organizações nucleares, utilizando o Instituto de Pesquisas Energéticas e Nucleares como unidade de pesquisa e coleta de dados. Os indicadores e variáveis latentes do instrumento foram definidos utilizando como referência modelos de avaliação de cultura de segurança da área da saúde e área nuclear. O instrumento de coleta de dados proposto inicialmente foi submetido à avaliação por especialistas da área nuclear e, posteriormente, ao pré-teste com indivíduos que pertenciam à população pesquisada. A validação do modelo foi feita por meio da modelagem por equações estruturais utilizando o método de mínimos quadrados parciais (Partial Least Square - Structural Equation Modeling PLS-SEM), no software SmartPLS. A versão final do instrumento foi composta por quarenta indicadores distribuídos em nove variáveis latentes. O modelo de mensuração apresentou validade convergente, validade discriminante e confiabilidade e, o modelo estrutural apresentou significância estatística, demonstrando que o instrumento cumpriu adequadamente todas as etapas de validação.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Cross, Richard J. (Richard John). "Inference and Updating of Probabilistic Structural Life Prediction Models." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19828.
Повний текст джерелаKoneru, Narendra. "Quantitative analysis of domain testing effectiveness." [Johnson City, Tenn. : East Tennessee State University], 2001. http://etd-submit.etsu.edu/etd/theses/available/etd-0404101-011933/unrestricted/koneru0427.pdf.
Повний текст джерелаZelenke, Brian Christopher. "An empirical statistical model relating winds and ocean surface currents : implications for short-term current forecasts." Thesis, Connect to the title online, 2005. http://hdl.handle.net/1957/2166.
Повний текст джерелаBrooks, Jeremy. "A Singular Perturbation Approach to the Fitzhugh-Nagumo PDE for Modeling Cardiac Action Potentials." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/honors/152.
Повний текст джерелаMasiulaitytė, Inga. "Regresiniai ir degradaciniai modeliai patikimumo teorijoje ir išgyvenamumo analizėje." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100527_134940-11585.
Повний текст джерелаIn doctoral thesis redundant systems and degradation models are considered. To ensure high reliability of important elements of the system, the stand-by units can be used. These units are commuted and operate instead of the main failed unit. The stand-by units can function in the different conditions: “hot”, “cold” or “warm” reserving. In the thesis systems with “warm” stand-by units are analyzed. Hypotheses of smooth commuting are formulated and goodness-of-fit tests for these hypotheses are constructed. Nonparametric and parametric point and interval estimation procedures are given. Modeling and statistical estimation of reliability of systems from failure time and degradation data are considered.
Arendt, Christopher D. "Adaptive Pareto Set Estimation for Stochastic Mixed Variable Design Problems." Ft. Belvoir : Defense Technical Information Center, 2009. http://handle.dtic.mil/100.2/ADA499860.
Повний текст джерелаTaoufik, Sanae. "Fiabilité et analyse de défaillance des tags RFID UHF passifs sous contraintes environnementales sévères." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR009/document.
Повний текст джерелаNowadays, RFID has strongly developed in many industrial applications, including the aeronautics and automotive sectors, where there is a strong demand for auto-identification systems operating in severe environments. In this context, the objective of this thesis is to study the effects of thermal storage on the reliability of passive UHF RFID tags. To achieve this, we adopted a consistent methodology. The first step of this methodology was to choose the tag under test. Two types of tags Web and Tageos from two different manufacturers are aged under high temperatures. The second step was to define the parameters of the aging tests and to characterize the aged tags. Using a dedicated measurement bench, the reflected power is measured after each aging phase for all tested tags to determine the power loss caused by the high temperature storage. Reflected power decrease significantly after each aging phase with different dynamics of degradation for all aged tags. This dynamics of degradation depends on the temperature test and the type of tag. The final step involved statistical and physical failure analysis. Clear differences about modes, mechanisms and failure times between Web and Tageos tags have been observed, it seems that Tageos tags are more reliable than Web tags. Failure analysis of the samples, using an optical microscope and SEM, has revealed, cracks in the antenna metallic conductors on a part of the aged tags. In another part of the tags, no failures in the antenna have been seen, but clear deformations at the polymer matrix of the ACP have been observed, thus changing the impedance matching between the RFIC and the antenna. Simulations using the COMSOL multiphysics software have been implemented in order to reproduce the experimental failure mechanisms. This thesis work has demonstrated the importance of studying the effects of high temperature storage on the reliability of passive RFID tags. Failures appeared faster and tests cost considerably less than other types of accelerated aging tests
Clavareau, Julien. "Modélisation des stratégies de remplacement de composant et de systèmes soumis à l'obsolescence technologique." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210482.
Повний текст джерелаLa sûreté de fonctionnement est progressivement devenue partie intégrante de l’évaluation des performances des systèmes industriels. En effet, les pannes d’équipements, les pertes de production consécutives, et la maintenance des installations ont un impact économique majeur dans les entreprises. Il est donc essentiel pour un manager de pouvoir estimer de manière cohérente et réaliste les coûts de fonctionnement de l’entreprise, en tenant notamment compte des caractéristiques fiabilistes des équipements utilisés, ainsi que des coûts induits entre autres par le non-fonctionnement du système et la restauration des performances de ses composants après défaillance.
Le travail que nous avons réalisé dans le cadre de ce doctorat se concentre sur un aspect particulier de la sûreté de fonctionnement, à savoir les politiques de remplacement d’équipements basées sur la fiabilité des systèmes qu’ils constituent. La recherche menée part de l’observation suivante :si la littérature consacrée aux politiques de remplacement est abondante, elle repose généralement sur l’hypothèse implicite que les nouveaux équipements envisagés présentent les mêmes caractéristiques et performances que celles que possédaient initialement les composants objets du remplacement.
La réalité technologique est souvent bien différente de cette approche, quelle que soit la discipline industrielle envisagée. En effet, de nouveaux équipements sont régulièrement disponibles sur le marché ;ils assurent les mêmes fonctions que des composants plus anciens utilisés par une entreprise, mais présentent de meilleures performances, par exemple en termes de taux de défaillance, consommation d’énergie, " intelligence " (aptitude à transmettre des informations sur leur état de détérioration).
De plus, il peut devenir de plus en plus difficile de se procurer des composants de l’ancienne génération pour remplacer ceux qui ont été déclassés. Cette situation est généralement appelée obsolescence technologique.
Le but de ce travail est de prolonger et d’approfondir, dans le cadre de la sûreté de fonctionnement, les réflexions engagées par les différents articles présentés dans la section état de l’art afin de définir et de modéliser des stratégies de remplacements d’équipements soumis à obsolescence technologique. Il s’agira de proposer un modèle, faisant le lien entre les approches plus économiques et celles plus fiabilistes, permettant de définir et d’évaluer l’efficacité, au sens large, des différentes stratégies de remplacement des unités obsolètes. L’efficacité d’une stratégie peut se mesurer par rapport à plusieurs critères parfois contradictoires. Parmi ceux-ci citons, évidemment, le coût total moyen engendré par la stratégie de remplacement, seul critère considéré dans les articles cités au chapitre 2, mais aussi la façon dont ces coûts sont répartis au cours du temps tout au long de la stratégie, la variabilité de ces coûts autour de leur moyenne, le fait de remplir certaines conditions comme par exemple d’avoir remplacé toutes les unités d’une génération par des unités d’une autre génération avant une date donnée ou de respecter certaines contraintes sur les temps de remplacement.
Pour arriver à évaluer les différentes stratégies, la première étape sera de définir un modèle réaliste des performances des unités considérées, et en particulier de leur loi de probabilité de défaillance. Etant donné le lien direct entre la probabilité de défaillance d’un équipement et la politique de maintenance qui lui est appliquée, notamment la fréquence des maintenances préventives, leur effet, l’effet des réparations après défaillance ou les critères de remplacement de l’équipement, un modèle complet devra considérer la description mathématique des effets des interventions effectuées sur les équipements. On verra que la volonté de décrire correctement les effets des interventions nous a amené à proposer une extension des modèles d’âge effectif habituellement utilisés dans la littérature.
Une fois le modèle interne des unités défini, nous développerons le modèle de remplacement des équipements obsolètes proprement dit.
Nous appuyant sur la notion de stratégie K proposée dans de précédents travaux, nous verrons comment adapter cette stratégie K à un modèle pour lequel les temps d’intervention ne sont pas négligeables et le nombre d’équipes limité. Nous verrons aussi comment tenir compte dans le cadre de cette stratégie K d’une part des contraintes de gestion d’un budget demandant en général de répartir les coûts au cours du temps et d’autre part de la volonté de passer d’une génération d’unités à l’autre en un temps limité, ces deux conditions pouvant être contradictoires.
Un autre problème auquel on est confronté quand on parle de l’obsolescence technologique est le modèle d’obsolescence à adopter. La manière dont on va gérer le risque d’obsolescence dépendra fortement de la manière dont on pense que les technologies vont évoluer et en particulier du rythme de cette évolution. Selon que l’on considère que le temps probable d’apparition d’une nouvelle génération est inférieur au temps de vie des composants ou supérieur à son temps de vie les solutions envisagées vont être différentes. Lors de deux applications numériques spécifiques.
Nous verrons au chapitre 12 comment envisager le problème lorsque l’intervalle de temps entre les différentes générations successives est largement inférieur à la durée de vie des équipements et au chapitre 13 comment traiter le problème lorsque le délai entre deux générations est de l’ordre de grandeur de la durée de vie des équipements considérés.
Le texte est structuré de la manière suivante :Après une première partie permettant de situer le contexte dans lequel s’inscrit ce travail, la deuxième partie décrit le modèle interne des unités tel que nous l’avons utilisé dans les différentes applications. La troisième partie reprend la description des stratégies de remplacement et des différentes applications traitées. La dernière partie permet de conclure par quelques commentaires sur les résultats obtenus et de discuter des perspectives de recherche dans le domaine.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Zhang, Xiao. "Confidence Intervals for Population Size in a Capture-Recapture Problem." Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etd/2022.
Повний текст джерелаGazendam, Albert Dirk. "The design of physical and logical topologies for wide-area WDM optical networks." Diss., 2003. http://hdl.handle.net/2263/23541.
Повний текст джерелаDissertation (MEng)--University of Pretoria, 2005.
Electrical, Electronic and Computer Engineering
unrestricted
Park, Il Hyeok. "Latent growth models and reliability estimation of longitudinal physical performances." Thesis, 2002. http://hdl.handle.net/2429/13212.
Повний текст джерелаChipoyera, Honest Walter. "Inspection and replacement models for reliability and maintenance: filling in gaps." Thesis, 2017. http://hdl.handle.net/10539/23607.
Повний текст джерелаThe work done in this thesis on finite planning horizon inspection models has demonstrated that with the advent of powerful computers these days it is possible to easily find an optimal inspection schedule when the lifetime distribution is known. For the case of system time to failure following a uniform distribution, a result for the maximum number of inspections for the finite planning models has been derived. If the time to failure follows an exponential distribution, it has been noted that periodically carrying out inspections may not result in maximization of expected profit. For the Weibull distributions family (of which the exponential distribution is a special case), evenly spreading the inspections over a given finite planning horizon may not lead to any serious prejudice in profit. The case of inspection models where inspections are of non-negligible duration has also been explored. The conditions necessary for inspections that are evenly spread over the entire planning horizon to be near-optimal when system time to failure either follows a uniform distribution or exponential distribution have been explored. Finite and infinite planning horizon models where inspections are imperfect have been researched on. Interesting observations on the impact of Type I and Type II errors in inspection have been made. These observations are listed on page 174. A clear and easy to implement road map on how to get an optimal inspection permutation in problems first discussed by Zuckerman (1989) and later reviewed by Qiu (1991) for both the undiscounted and discounted cases has been given. The only challenge envisaged when a system has a large number of components is that of computer memory requirements - which nowadays is fast being overcome. In particular, it has been clearly demonstrated that the impact of repair times and per unit of time repair costs on the optimal inspection permutation cannot be ignored. The ideas and procedures of determining optimal inspection permutations which have been developed in this thesis will no doubt lead to huge cost savings especially for systems where the cost of inspecting components is huge.
XL2018
"Determination of Dominant Failure Modes Using Combined Experimental and Statistical Methods and Selection of Best Method to Calculate Degradation Rates." Master's thesis, 2014. http://hdl.handle.net/2286/R.I.26838.
Повний текст джерелаDissertation/Thesis
Masters Thesis Engineering 2014
Rokneddin, Keivan. "RELIABILITY AND RISK ASSESSMENT OF NETWORKED URBAN INFRASTRUCTURE SYSTEMS UNDER NATURAL HAZARDS." Thesis, 2013. http://hdl.handle.net/1911/72034.
Повний текст джерелаAlgee-Hewitt, Bridget Frances Beatrice. "If and How Many 'Races'? The Application of Mixture Modeling to World-Wide Human Craniometric Variation." 2011. http://trace.tennessee.edu/utk_graddiss/1165.
Повний текст джерела