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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Desenvolvimento de metodologia para parametrização de equipamentos mecânicos pressurizados / Development of methodology for parameterization of pressurized mechanical equipments

Alan Garcia Santos 07 October 2011 (has links)
Trata do desenvolvimento de uma metodologia para parametrização de equipamentos mecânicos pressurizados. Objetiva criar sistemas para geração de famílias de equipamentos petroquímicos e reduzir o tempo total de elaboração do projeto, desenhos e listas de materiais em até 80%, diminuir em até 70% o tempo consumido na geração de fichas de corte e mapas de solda na execução de roteiros de fabricação e ainda aprimorar a aquisição de materiais e componentes devido à padronização das entradas de projeto. Relata que os sistemas CAD (Computer-Aided Design) tridimensionais paramétricos têm papel cada vez mais destacado no desenvolvimento de equipamentos, porém alguns setores tradicionais da indústria brasileira apresentam ainda certa resistência ao emprego desta tecnologia. Demonstra que diante dos desafios impostos pela exploração de petróleo na camada do Pré-Sal e o grande volume de investimentos da PETROBRAS na expansão do setor produtivo ligado à extração e refino de petróleo, as empresas fornecedoras de equipamentos para o setor petroquímico são obrigadas a se modernizar e buscar novos paradigmas de projeto e fabricação para atender à demanda. Explica que o emprego produtivo de sistemas CAD 3D paramétricos se torna essencial neste cenário. Aplica a metodologia que foi desenvolvida baseada na abordagem top-down para modelagem de montagens, e afirma esta metodologia pode ser adaptada a qualquer sistema CAD 3D paramétrico comercial, com baixo consumo de recursos computacionais. Apresenta para validação um exemplo de aplicação passo a passo da metodologia para um equipamento. Mostra que a metodologia foi aplicada também para a construção de uma família de vasos de pressão verticais suportados por saia, com o intuito de avaliar o desempenho, com a obtenção de resultados significativos. Discute os problemas e dificuldades enfrentados na implantação do sistema paramétrico, juntamente com as alterações que este sistema trás na estrutura organizacional tradicional de empresas de bens de capital. Conclui que a metodologia desenvolvida apresentou resultados dentro dos objetivos estabelecidos e é uma alternativa viável para projetos mecânicos, que possibilita ganho de produtividade significativo. / This work addresses a methodology for the parameterization of pressurized mechanical equipments. It focuses on creating systems to generate an assembly of petrochemical equipments, hence reducing the total time of project designs, layouts and bill of material until 80%, decreasing until 70% the time consumed for executing manufacturing instructions and also improving materials and components acquisition due to the standardization of project entries. The study reports that three-dimensional parametric CAD systems (Computer-Aided Design) have an increasingly prominent role in the development of equipments, however some traditional sectors in the Brazilian industry are still somewhat resistant to using this technology. This work shows that with the challenges posed by oil exploration in the pre-salt layer and PETROBRAS large investments in the productive expansion sector for oil extraction and refining, the equipment supply companies servicing the petrochemical industry are forced to modernize and seek new design and manufacturing paradigms to meet the demands. It explains that the productive use of 3D parametric CAD systems are essential in this scenario. The methodology that was developed based on the top-down approach for assembly modeling is applied, thereby showing that this methodology can be adapted to any commercial 3D parametric CAD system, with low computational consumption of resources. For validation, it shows a step by step application example of the methodology in one equipment. It shows that the methodology was also applied to the construction of a family of skirt supported vertical pressure vessels, in order to evaluate the performance, with significant results. This work discusses the problems and difficulties faced in implementing the parametric system, along with the changes this system brings in the traditional organizational structure of capital goods companies. It concludes that this methodology presented results within the stated objectives and that it is a viable alternative for mechanical designs, hence enabling significant productivity gains.
52

Implementação de rotinas computacionais para o cálculo de trajetórias geodésicas no processo de filament winding / Computational routines for the calculation of geodesic paths in filament winding process

Edgar dos Santos Gomes 18 May 2009 (has links)
Materiais compósitos são conhecidos pela alta resistência mecânica e baixo peso, desempenho superior, resistência à corrosão e baixa densidade. A produção de um material composto possui vários processos com particularidades diferentes. O enrolamento filamentar (Filament Winding) é um processo no qual fibras de reforço contínuas são posicionadas de maneira precisa e de acordo com um padrão predeterminado para compor a forma do componente desejado. As fibras, submetidas à tração, são enroladas continuamente ao redor de um mandril que tem a forma do produto final, em geral utilizando equipamentos automáticos. No final do processo, após a cura da resina, o mandril é geralmente removido. Desta forma, é de fundamental importância que o projetista disponha de recursos computacionais adequados para o cálculo das trajetórias e sequenciamento de posicionamento das fibras. Esse trabalho tem como objetivo o desenvolvimento de procedimentos matemáticos para cálculo de trajetórias geodésicas no processo de \"Filament Winding\" e implementá-los em um ambiente computacional em linguagem de alto nível Java, considerando-se os casos de revestimento circunferencial, helicoidal e polar. São desenvolvidos dois estudos de caso: tubos cônicos e vasos de pressão, e os resultados apresentados e discutidos, validando os procedimentos e ambiente implementado. / Composite materials are well known by the high strength and low weight, superior performance, resistance to the corrosion and low density. The production of a composite material part involves some processes with different requirements. The filament winding process is an automated process in which continuous reinforcement fibers are lay down in prescribed paths on the surface of a mandrel, which is generally removed after the cure of the resin. In such a way, it is fundamental that the designer uses computational resources for the calculation of the paths and sequence of the fibers. In this work is developed the mathematical procedures for calculation of geodesic trajectories in the Filament Winding process and implements them in a computational environment in high level language Java, considering the circumferential, helical and polar strategies. Two case studies are developed successfully: conical pipes and pressure vessels, and the results presented and discussed, validating the procedures and implemented environment.
53

Analyse et intégration des spécificités liées au procédé de fabrication dans les modèles de calcul des structures composites : application à la simulation du comportement mécanique des fonds des réservoirs bobinés / Analysis and integration of the specificities related to the manufacturing process in computational models of composite structures : Application to modeling mechanical behavior in the domes of the wound composite pressure vessels.

El moussaid, Mohammed 06 June 2016 (has links)
Les réservoirs en matériaux composites représentent un moyen pourle stockage de l’hydrogène à des pressions de service très élevées. En dépit desnombreux avantages que présentent les réservoirs en composites, le stockage soushaute pression conduit à utiliser de fortes épaisseurs de composites, et lecomportement de ce type de structure reste mal maitrisé. Le procédé d’enroulementfilamentaire induit des variabilités et défauts qui impactent le comportement de lastructure et en particulier le comportement des fonds. De ce fait, il est nécessaired'apprécier ces variabilités dans la modélisation du comportement des réservoirscomposites épais.Ce travail de thèse présente une approche permettant de modéliser le comportementmécanique des réservoirs en prenant en compte les spécificités dues au procédé deréalisation. A ce titre, nos recherches concernent aussi bien l'analyse de structuresque l'aspect simulation numérique. / Les réservoirs en matériaux composites représentent un moyen pourle stockage de l’hydrogène à des pressions de service très élevées. En dépit desnombreux avantages que présentent les réservoirs en composites, le stockage soushaute pression conduit à utiliser de fortes épaisseurs de composites, et lecomportement de ce type de structure reste mal maitrisé. Le procédé d’enroulementfilamentaire induit des variabilités et défauts qui impactent le comportement de lastructure et en particulier le comportement des fonds. De ce fait, il est nécessaired'apprécier ces variabilités dans la modélisation du comportement des réservoirscomposites épais.Ce travail de thèse présente une approche permettant de modéliser le comportementmécanique des réservoirs en prenant en compte les spécificités dues au procédé deréalisation. A ce titre, nos recherches concernent aussi bien l'analyse de structuresque l'aspect simulation numérique.
54

Monitoring of pipeline using smart sensors

Nugroho, Wibowo Harso, 1967- January 2001 (has links)
Abstract not available
55

Application of Statistical Methodology on Monitoring the Failure Conditions of Static Equipments in the Petroleum Process

Chen, Chun-hung 13 December 2008 (has links)
In overwhelming majority of the petroleum or petrochemical plants, pressure vessels and process piping play important roles among the major elements of static equipments. So, based on the integrity of safety management for the petroleum or petrochemical plants and reduction of the operation risks, some objective schemes of the systematic failure evaluations and assessments should be established in order to optimize the resources of inspection and maintenance. However, performing the inspections based on the conventional methodologies, some uncontrolled factors which caused by the environments and inspection methods may exist and affect the assessment of the estimated corrosion rate. If the influences of the uncontrolled factors were not considered and compensated in the assessment of the estimated corrosion rate, some underestimate or unreasonable results would be obtained which lead potential risks may exist in the plants. Moreover, the measured data of some parameters, for example, operation pressure, corrosion condition, allowable stress, which were used to evaluate the estimated corrosion rate of the pressure components may exhibit a normal or non-normal distribution. Under such circumferences, if one used the nominal values of the measured parameters to assessment the safety conditions of the pressure components, potential risks may exist in the petroleum or petrochemical plants at the final stage of long-term operation. With an eye to obtain more conservative and objective assess results for pressure equipments in the long-term operation, three subjects will be differentiated between the evaluation of estimated corrosion rate, failure probability of pressure vessels and pressure safety valve (PSVs). First, based on the pressure boundaries suffered from general corrosion, a statistical methodology was proposed to modify the assessment of estimated corrosion rates for the pressure components in conventional methodology. Furthermore, the obtained results of the estimated corrosion rates will be used to assess the failure probability of pressure components based on the upper limited value. By adopting First Order Second Moment (FOSM) method, the failure probability was approached for the pressure components in long term operation. Moreover, for the sake of optimize the inspection and maintenance resources based on the acceptable risk of the plant owners, typical semi-quantitative risk based inspection (RBI) methodology to each pressure vessel are proposed in safety management based on the approached failure probability. Besides, the final protection for the pressure equipments when the pressure systems were upset - pressure safety valves (PSVs), are also play important roles to system evaluation and safety management for pressurized system. So, follow the semi-quantitative RBI methodology, the objective evaluation schemes together with the suggested inspection interval were conservatively established. Based on the conclusion of the studies, few pressure components with high failure probability will raise the operation risk of the pressurized system. It is an effective way to reduce the operation risk of the pressurized system by shift the limited resource of inspection/maintenance on the pressure components with high risk and obtain further control with effective strategies. Moreover, the conclusion also shows the prospective inspection intervals of PSVs which time-based strategy according to the local regulations (2-year based) should be change to condition-based strategy to reduce the operation risk.
56

WTZ Russland - Fluenzberechnungen für Voreilproben beim WWER-440

Konheiser, Jörg, Grahn, Alexander 29 October 2014 (has links) (PDF)
Der Reaktordruckbehälter (RDB) zählt zu den nicht auswechselbaren Komponenten eines Kernkraftwerkes (KKW). Durch die hohen Neutronen- und Gammaflüsse ist er beschleunigten Alterungsprozessen unterworfen, welche die Lebensdauer eines KKW bestimmen könnten. So haben neben der chemischen Zusammensetzung des RDB-Stahls vor allem die Strahlungsparameter (Neutronen- und Gammafluenzen und deren Spektren) Auswirkungen auf die Versprödungseigenschaften des RDB. Für einen sicheren Betrieb eines KKW ist es daher sehr wichtig, die mögliche Änderung des Materialzustandes vom RDB im Voraus bewerten zu können. Die sogenannten Voreilprobenprogramme gehören deshalb zu den wichtigsten Überwachungsmaßnahmen im KKW. Mit ihnen kann die Restlebensdauer des RDB realistisch und zuverlässig beurteilt werden. In dieser Arbeit werden, neben der Bestimmung der Fluenzen an sich, auch Auswirkungen auf den Teilchenfluss in den Voreilproben, wie zum Beispiel die verschiedenen geometrischen Positionen, untersucht. Damit können mögliche Unsicherheiten bei der Bestimmung der realen Fluenzwerte abgeschätzt werden. Die Berechnungen wurden sowohl mit dem Code TRAMO als auch mit dem Code DORT durchgeführt. Die berechneten Ergebnisse wurden an Aktivierungsmonitoren, die an der RDBAußenoberfläche des KKW Kola, Unit 3 (WWER-440/213), bestrahlt wurden, überprüft. Hauptsächlich kamen Aktivierungsmonitore mit den Reaktionen 54Fe(n,p)54Mn und 58Ni(n,p)58Co zum Einsatz. Die Aktivitätsmessungen wurden vom russischen Partner, dem „Scientific and Engineering Centre for Nuclear and Radiation Safety“ (SEC NRS) durchgeführt. Es konnte gute Übereinstimmung sowohl zwischen den deterministischen und den stochastischen Berechnungsergebnissen als auch zwischen den berechneten und gemessenen Ergebnissen erzielt werden. Die durchschnittliche Differenz zwischen gemessenen und berechneten Werten betrug nur 5%. Ein Einfluss der Bestrahlungskanäle und der Versteifungsrippen der Kernumfassung auf die Monitoraktivität konnte festgestellt werden. Für die Voreilproben im Bereich des Flussmaximums wurden für den Neutronenfluss E> 0.5 MeV ein Mittelwert von rund 2.45*1012 Neutronen/cm2 berechnet. Dabei können die Unterschiede in Abhängigkeit von der Ausrichtung der Proben zum Reaktorkern bis zu 20% betragen. Abweichungen bis zu 10% können durch die Änderung der Position der Bestrahlungskapseln im Kanal entstehen. Auf Basis dieser Rechnungen wurden die Voreilfaktoren der Bestrahlungsproben bestimmt. Bei mittleren Zykluslängen würde die „End of Life“-Fluenz in den Bestrahlungsproben bereits nach 2 Jahren erreicht werden. Der berechnete maximale Gammafluss beträgt rund 3.4*1012 g/cm2s für E > 1.0 MeV und rund 8.4*1012 g/cm2s für E > 0.5 MeV, wobei der größte Anteil des Flusses (rund 97%) aus Neutronenreaktionen stammt. Damit sind die Gammaflüsse in den Proben zwei bis drei Mal so groß wie die der Neutronen. Trotzdem spielt die Materialschädigung durch die Gammastrahlung eine untergeordnete Rolle, da die DPAQuerschnitte (displacement per atom) von Gammas um etwa zwei bis drei Größenordnungen kleiner sind. Des Weiteren wurde untersucht, ob mögliche Ausheilprozesse durch zu hohe Temperaturen in den Bestrahlungsproben stattfinden könnten. Zu diesem Zweck wurde der Energieeintrag in den Bestrahlungsproben basierend auf den berechneten Teilchenflüssen bestimmt und mit einfachen thermohydraulischen Modellen die mögliche Aufheizung ermittelt. Eine Temperaturerhöhung von rund 20 K wurde mit einem konservativen Ansatz berechnet. Unter vergleichsweise realistischen Bedingungen reduzierte sich die Aufheizung auf unter 5 K. / Reactor pressure vessels (RPV) are non-restorable equipment and their lifetime may restrict the nuclear power plant-life as a whole. Surveillance specimen programs for RPV materials are among the most important measures of in-service inspection pro-grams that are necessary for realistic and reliable assessment of the RPV residual lifetime. In addition to the chemical composition of the RPV steel, the radiation pa-rameters (neutron and gamma fluences and spectra) have the most important impact on the RPV embrittlement characteristics. In this work, different geometric positions which have influence on the radiation conditions of the samples are investigated. Thus, the uncertainties can be determined in the fluence values of surveillance specimens. The fluence calculations were carried out by the codes TRAMO and DORT. This study was accompanied by ex-vessel neutron dosimetry experiments at Kola NPP, Unit 3 (VVER-440/213), which provide the basis for validation of calculated neutron fluences. The main neutron-activation monitoring reactions were 54Fe(n,p)54Mn and 58Ni(n,p)58Co. The activity measurements were carried out by “Scientific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS). Good agreement between the deterministic and stochastic calculation results as well as between the calculations and the ex-vessel measurements was found. The aver-age difference between measured and calculated values is 5%. The influence of the channels for surveillance specimens and the shielding effect of a baffle rib on the monitors and on the Monte-Carlo calculated results was studied. For the surveillance specimens in the maximum of the flux, an average flux of around 2.45 * 1012 neutrons/cm2 was calculated for the neutron flux E> 0.5 MeV. The differences in the surveillance specimens could be up to 20% depending on the direction to the core. Discrepancies up to 10% can be caused by the change of the position of the capsules in the irradiation channel. Based on these calculations the lead factor of specimens was determined. The maximum fluence of RPV may be achieved after two cycles. The calculated maximum gamma flux is around 3.4 * 1012 g/cm2s for E> 1.0 MeV and around 8.4 * 1012 g/cm2s for E> 0.5 MeV, with the largest part of the flux (around 97%) from the neutron reactions. The gamma fluxes in the surveillance specimens are two to three times bigger than the neutron fluxes. Nevertheless, the material damage by the gamma radiation is very small, because the dpa (displacement per atom) cross sections of gamma rays are about two to three orders of magnitude smaller. In order to exclude the possibility of healing effects of the samples due to excessive temperatures, the heat release in the surveillance specimens was determined based on the calculated gamma fluences. The analytic treatment of the heat conduction equation and simplified SS geometries were adopted to calculate the range of tem-peratures to be expected. The temperature increase of 20 K above the inlet coolant temperature was estimated using a conservative approach. Under comparatively re-alistic conditions, the heating was reduced to less than 5 K.
57

Top-down scaling analysis of the integral reactor vessel test facility

Graves, Joshua D. 07 December 2012 (has links)
Oregon State University has conducted research in collaboration with TerraPower, LLC, to perform a top-down scaling analysis of an integrated test facility. The goal of this facility is to simulate transient and quasi-steady phenomena at a reduced scale, including steady-state operation, pump coastdown, natural circulation, reactor head heat transfer, and coolant stratification. To support this goal, this thesis presents the methodology and analysis by which approximate facility dimensions were generated. This analysis includes implementation of the hierarchical two-tiered scaling methodology, as outlined by the Nuclear Regulatory Commission and optimization through the general reduced gradient methodology. / Graduation date: 2013
58

A discussion of the problems involved in the defection [sic] of fuel element leaks in a sodium cooled reactor [Masters thesis] /

Wegst, Walter Frederick, January 1957 (has links)
Thesis (M.S.)--University of Michigan, 1957.
59

Medidas de permeabilidade e de condutividade termica efetiva em isolamentos termicos do tipo fibra

SKODA, SANDRO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:29:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:41Z (GMT). No. of bitstreams: 1 01303.pdf: 5678711 bytes, checksum: bea6566350f10df4fb3cd2f58bc36973 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
60

Analise experimental de um modelo de V.P.C.P. para reator nuclear

VALLIN, CELSO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:30:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:00Z (GMT). No. of bitstreams: 1 01112.pdf: 4081809 bytes, checksum: 8bc8c990027f72b27ae11db41cc3b5b6 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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