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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.
31

Produção, estabilização e caracterização de redes fotorrefrativas de período longo em fibras óticas para sensores

Costa, Rita Zanlorensi Visneck 2010 October 1914 (has links)
Este trabalho apresenta a implementação do sistema de gravação de redes de período longo, através da técnica de incidência lateral de radiação ultravioleta ponto-a-ponto, no Laboratório de Laser da UTFPR. Foram escritas redes em fibras óticas com o uso de um laser de Nd:YAG operando em 266 nm. A evolução espectral das redes foi analisada tanto durante o processo de escrita quanto após o seu término, ao longo de intervalos que variaram de 1 a 595 horas. Essas redes foram submetidas a várias caracterizações com vistas à sua aplicação no sensoriamento de parâmetros físico-químicos. Na avaliação da sensibilidade ao índice de refração do meio externo às redes, foram utilizados fluidos com índices de refração entre 1,0000 e 1,4315. Registraram-se alterações na sensibilidade térmica de valores negativos para positivos, para variações de temperatura de até 24°C, com mudanças de comportamentos lineares para não lineares, dependendo do índice de refração do meio. No ensaio para caracterização da resposta às deformações longitudinais a rede analisada demonstrou-se pouco sensível, com um valor obtido de sensibilidade de -0,19 ± 0,15 pm/µe na faixa de 0 a 125 µe. Foram feitos testes da caracterização térmica desses dispositivos, utilizando um elemento Peltier e um forno de laboratório. Com o uso do elemento Peltier as redes de período longo passaram por ciclos de aquecimento e resfriamento compreendidos entre -1,5°C e 61,1°C. Já no forno de laboratório, as redes chegaram a ser submetidas a temperaturas que variaram de 25°C a 1200°C sem serem completamente apagadas. Uma das questões experimentais mais determinantes foi a investigação da estabilização térmica das redes. Para tanto foram testados e comparados dois diferentes processos de estabilização. O primeiro consistiu em submeter a rede a ciclos de recozimento seguidos de resfriamento lento e o segundo a ciclos de recozimento seguidos de resfriamento brusco, nos quais a máxima temperatura atingida pelas redes foi de 425°C. O segundo método demonstrou-se mais eficaz para o propósito de estabilização térmica. A rede estabilizada mostrou uma sensibilizada térmica não linear que variou de -0,044 nm/°C quando aquecida de 20°C a 300°C. Em função das características assimétricas inerentes ao processo empregado para escrita das redes, foram realizados ensaios para verificar a viabilidade da utilização desses dispositivos como transdutores para medição de curvatura em diferentes direções, com emprego de redes neurais artificiais para análise desses dados. / This work shows the implementation of a writing system for long-period gratings production, by using a side point-by-point ilumination with ultraviolet light, at Laser Laboratory in UTFPR. Gratings were written in optical fibers with a Nd: YAG laser operating at 266 nm. The spectral evolution of gratings was analyzed both during and after the writing process, along time intervals from 1 to 595 hours. The gratings were submitted to several characterizations aiming its application in physicochemical parameters sensing. For the assessment of gratings sensitivity to the external medium refractive index, fluid samples with refractice indices ranging from 1,0000 to 1.4315 were used. Changes of thermal sensitivity from negative do positive values were quantified, for temperature variations up to 24°C, with behaviours transitioning from linear to nonlinear, depending on the refractive index of external medium. For the studies of sensitivities of longitudinal strain, the analyzed grating showed a low sensitivity value of -0,19±0,15 pm/µe in the range between 0 to 125 µe. A thermal characterization of the produced devices was carried out with a thermo element Peltier and with a laboratory furnace. For the Peltier the gratings were submitted to thermal cycles from -1,5°C to 61.1°C. For the furnace the gratings were exposed to temperatures between 25°C a 1200°C without completely erased. An experimental issue was the investigation about the thermal stabilization of gratings. Two different processes to reach the thermal stabilization were studied: annealing and quenching. The former consisted of annealing cycles with slow cooling whereas the later comprised of thermal cycles with sudden cooling from a maximum temperature of 425°C, the second one revealing to be more efficient to reach the thermal stabilization. The stabilized grating showed a non-linear thermal sensitivity ranging from -0,044 nm/°C within the temperature range from 20°C to 300°C. Owing to the inherent asymmetric characteristics of the process employed to record the gratings, the viability of using such devices as transducers for curvature sensing in different directions was studied, employing artificial neural networks to analyze the data.
32

Produção, estabilização e caracterização de redes fotorrefrativas de período longo em fibras óticas para sensores

Costa, Rita Zanlorensi Visneck 2010 October 1914 (has links)
Este trabalho apresenta a implementação do sistema de gravação de redes de período longo, através da técnica de incidência lateral de radiação ultravioleta ponto-a-ponto, no Laboratório de Laser da UTFPR. Foram escritas redes em fibras óticas com o uso de um laser de Nd:YAG operando em 266 nm. A evolução espectral das redes foi analisada tanto durante o processo de escrita quanto após o seu término, ao longo de intervalos que variaram de 1 a 595 horas. Essas redes foram submetidas a várias caracterizações com vistas à sua aplicação no sensoriamento de parâmetros físico-químicos. Na avaliação da sensibilidade ao índice de refração do meio externo às redes, foram utilizados fluidos com índices de refração entre 1,0000 e 1,4315. Registraram-se alterações na sensibilidade térmica de valores negativos para positivos, para variações de temperatura de até 24°C, com mudanças de comportamentos lineares para não lineares, dependendo do índice de refração do meio. No ensaio para caracterização da resposta às deformações longitudinais a rede analisada demonstrou-se pouco sensível, com um valor obtido de sensibilidade de -0,19 ± 0,15 pm/µe na faixa de 0 a 125 µe. Foram feitos testes da caracterização térmica desses dispositivos, utilizando um elemento Peltier e um forno de laboratório. Com o uso do elemento Peltier as redes de período longo passaram por ciclos de aquecimento e resfriamento compreendidos entre -1,5°C e 61,1°C. Já no forno de laboratório, as redes chegaram a ser submetidas a temperaturas que variaram de 25°C a 1200°C sem serem completamente apagadas. Uma das questões experimentais mais determinantes foi a investigação da estabilização térmica das redes. Para tanto foram testados e comparados dois diferentes processos de estabilização. O primeiro consistiu em submeter a rede a ciclos de recozimento seguidos de resfriamento lento e o segundo a ciclos de recozimento seguidos de resfriamento brusco, nos quais a máxima temperatura atingida pelas redes foi de 425°C. O segundo método demonstrou-se mais eficaz para o propósito de estabilização térmica. A rede estabilizada mostrou uma sensibilizada térmica não linear que variou de -0,044 nm/°C quando aquecida de 20°C a 300°C. Em função das características assimétricas inerentes ao processo empregado para escrita das redes, foram realizados ensaios para verificar a viabilidade da utilização desses dispositivos como transdutores para medição de curvatura em diferentes direções, com emprego de redes neurais artificiais para análise desses dados. / This work shows the implementation of a writing system for long-period gratings production, by using a side point-by-point ilumination with ultraviolet light, at Laser Laboratory in UTFPR. Gratings were written in optical fibers with a Nd: YAG laser operating at 266 nm. The spectral evolution of gratings was analyzed both during and after the writing process, along time intervals from 1 to 595 hours. The gratings were submitted to several characterizations aiming its application in physicochemical parameters sensing. For the assessment of gratings sensitivity to the external medium refractive index, fluid samples with refractice indices ranging from 1,0000 to 1.4315 were used. Changes of thermal sensitivity from negative do positive values were quantified, for temperature variations up to 24°C, with behaviours transitioning from linear to nonlinear, depending on the refractive index of external medium. For the studies of sensitivities of longitudinal strain, the analyzed grating showed a low sensitivity value of -0,19±0,15 pm/µe in the range between 0 to 125 µe. A thermal characterization of the produced devices was carried out with a thermo element Peltier and with a laboratory furnace. For the Peltier the gratings were submitted to thermal cycles from -1,5°C to 61.1°C. For the furnace the gratings were exposed to temperatures between 25°C a 1200°C without completely erased. An experimental issue was the investigation about the thermal stabilization of gratings. Two different processes to reach the thermal stabilization were studied: annealing and quenching. The former consisted of annealing cycles with slow cooling whereas the later comprised of thermal cycles with sudden cooling from a maximum temperature of 425°C, the second one revealing to be more efficient to reach the thermal stabilization. The stabilized grating showed a non-linear thermal sensitivity ranging from -0,044 nm/°C within the temperature range from 20°C to 300°C. Owing to the inherent asymmetric characteristics of the process employed to record the gratings, the viability of using such devices as transducers for curvature sensing in different directions was studied, employing artificial neural networks to analyze the data.
33

Excelência logística e trabalho em equipe: estudo de caso em uma empresa distribuidora da GLP / Logistics excellence and teamwork: a case study in a LPG distribution company

Matheus de Aguiar Sillos 09 September 2011 (has links)
O presente trabalho objetiva identificar e analisar as dimensões de excelência logística, desenvolvidas como forma de se obter vantagens competitivas, buscando analisar a influência do trabalho organizado em equipes na excelência logística de uma organização do mercado de Gás Liquefeito de Petróleo. O trabalho foi realizado através de uma revisão bibliográfica sobre os temas excelência logística nas organizações e trabalho organizado em equipes. Como metodologia foi proposto um construto teórico de excelência logística e trabalho em equipe, realizado através de uma revisão bibliográfica sobre os temas, com a apresentação de um estudo de caso em uma empresa líder do mercado em que atua, de forma a ilustrar a aplicação dos conceitos propostos. Como resultado, o trabalho conclui que a organização do trabalho em equipes se mostra grande apoiadora das práticas de excelência logística nessa organização, integrando e possibilitando o desenvolvimento das diferentes dimensões de excelência logística. / This paper aims to identify and analyze the dimensions of logistics excellence, developed as a way to gain competitive advantage, seeking to analyze the influence of teamwork in the logistics excellence of a Liquefied Petroleum Gas organization. The study was conducted through a literature review on the issues logistics excellence in organizations and teamwork. The methodology has been proposed a theoretical construct of logistics excellence and teamwork, accomplished through a literature review on the issues, with the presentation of a case study in a leading company in the market it operates, in order to illustrate the application of concepts proposed. As a result, the paper concludes that the organization of teamwork is a strong supporter of logistics best practices in this organization, integrating and enabling the development of the different dimensions of logistics excellence.
34

Escolhas estratégicas na decisão sobre canais de distribuição em commodities: um estudo de caso no segmento de gás liquefeito de petróleo (GLP) / Strategic choices in decision making on distribution channels in commodities: a case study in liquefied petroleum gas (lpg) segment

Fernando Shigueo Omoto Bittar 20 September 2013 (has links)
O setor de Gás Liquefeito de Petróleo (GLP), produto considerado de primeira necessidade para a população brasileira, está inserido em um ambiente altamente competitivo devido a poucas barreiras de entrada, ao aumento da atratividade e à baixa diferenciação do produto. Nesse cenário, os sistemas de distribuição propiciam um componente de grande importância no que se refere à diferenciação e ao desenvolvimento de vantagens competitivas no varejo. Assim, o presente estudo tem como objetivo geral analisar os principais aspectos a serem levados em consideração na tomada de decisão sobre os canais de distribuição no segmento domiciliar de GLP, referente ao primeiro elo da cadeia (distribuidora para revenda de GLP). Como objetivos específicos, se destacam a verificação da relevância das variáveis encontradas na literatura para o mercado domiciliar de GLP e a verificação de uma tendência para o setor. Para isso, serão abordados referenciais teóricos sob a ótica da Organização Industrial (OI), da Nova Economia Institucional (NEI) e de Canais de Marketing. Buscando atingir os objetivos propostos, além da revisão teórica, foi realizado um levantamento histórico sobre o GLP e as principais distribuidoras brasileiras, o qual trouxe à tona fatos políticos e econômicos que influenciam até hoje as decisões dos agentes econômicos do setor. O método utilizado foi uma pesquisa qualitativa, por meio de um estudo de caso na maior empresa brasileira de distribuição de GLP, a Cia. Ultragaz S/A. Foram desenvolvidos e aplicados questionários semiestruturados, por meio de entrevistas com os executivos da alta direção da empresa e com um executivo da direção do Sindicato Nacional das Empresas Distribuidoras do Gás Liquefeito do Petróleo (SINDIGÁS), trazendo assim uma visão mais global do segmento. Após a aplicação do estudo de caso, foram encontrados resultados relevantes para a academia, dos quais pode ser citada a constatação de que não existe uma relação direta entre as variáreis \"ativos específicos\" e \"incerteza interna/comportamental\" com a escolha dos canais de distribuição. Outros resultados importantes provindos da análise dos dados foram: a ordenação dos fatores que determinam a escolha dos canais indiretos e a influência das relações de poder na tomada de decisão em canais de distribuição. Por fim, analisando a tendência do setor, o mercado de GLP não deve findar nos próximos 50 anos e, se isso ocorresse, as empresas atuais buscariam novos mercados fora do setor de energia. Dessa forma, apesar das limitações, as quais serão apresentadas ao final da presente dissertação, muitos estudos acadêmicos ainda podem ser desenvolvidos dentro desse setor de expressiva relevância econômica e social para o País. / The Liquefied Petroleum Gas (LPG) sector, a product deemed basic needs for the Brazilian population is placed in a highly competitive environment due to a few barriers to entry, the increase in attractiveness and low product differentiation. In this scenario, the distribution systems provide a component of great importance regarding differentiation and development of competitive advantages in the retail market. Thus, this study aims to conduct an analysis on the main aspects to be taken into consideration when deciding on the distribution channels in the LPG household segment, referring to the first link in the chain (LPG distributor for dealer). The specific objectives are: verifying the relevance of the variables found in the literature for the LPG residential market and verifying the trend for the sector. For this purpose theoretical perspectives will be discussed using Industrial Organization, New Institutional Economics and Marketing Channels. In order to reach the proposed aims, a survey was conducted on the LPG history and major Brazilian distributors besides the theoretical review, which brought up political and economic facts that influence present decisions of economic agents in the industry. The method used was a qualitative research by means of a case study in the largest Brazilian LPG distributor, Cia. Ultragaz S/A. Semi-structured questionnaires were developed and applied by means of interviews with executives from company top management and with an executive director of the National Association of Liquefied Petroleum Gas Distributors (SINDIGÁS), bringing out a global view of the segment. After the application of the case study, relevant results were found to the academy, which may be due to the fact that there is not a direct relationship between the variables \"specific assets\" and \"internal behavioral/uncertainty\" with the choice of the distribution channels. Other important results obtained from the data analysis were: the hierarchical ordering of factors that determine the choice of indirect channels and the influence of power relations in decision making on distribution channels. Finally, by analyzing the industry´s trends, the LPG market should not end in the next 50 years and, if it that happened, current companies would look for new markets outside the energy sector. Thus, despite the limitations, which will be presented at the end of this study, many academic studies can still be developed in a sector which presents economic and social relevancy for the country.
35

Servicio de Abastecimiento de GLP de la empresa MIGAS LIMA SA

Bustamante Palomino, Liz Evelyn, Delgado Herrera, Rosa Guadalupe, Estupiñan Peralta, Sandra Sofia 12 July 2020 (has links)
La empresa comercializadora de servicios MIGAS LIMA S.A emprende en la atención del mercado de abastecimiento de GLP a granel para abastecimiento y venta a empresas en los distritos de Lince, San Isidro, Miraflores y Barranco. Actualmente, desea aprovechar las favorables condiciones que genera la alta demanda de GLP para desarrollar una nueva línea de servicio digital que permita estar más involucrados como proveedor y cliente. Esta empresa, en etapa de creación, ha encontrado la necesidad de abastecimiento de un mercado que no es 100% atendido por la poca oferta que existe en la venta y reparto de gas a granel, ya que en la región Lima solo cuentan con 3 grandes proveedores: PETROPERÚ (Villa el Salvador), REPSOL (Ventanilla), LLAMAGAS (Independencia). Por lo tanto, el objetivo de este trabajo de investigación es demostrar la viabilidad del proyecto de MIGAS LIMA S.A en la búsqueda de desarrollar un proceso de venta y abastecimiento sólido y constante para su cartera de clientes y potenciales compradores, creando eficiencia e innovación desde las actividades principales de su cadena de valor, sobre todo en el plan de acción de su cadena logística e innovando en el sistema de control de consumo del gas y formas de facturación a través de un aplicativo que manejara de manera remota estas actividades en interacción con el cliente. / The service company MIGAS LIMA S.A undertakes to service the bulk LPG supply market for supply and sale to companies in the districts of Lince, San Isidro, Miraflores and Barranco. Currently, it wants to take advantage of the favorable conditions generated by the high demand for LPG to develop a new digital service line that allows it to become more involved as a supplier and customer. This company, in the creation stage, has found the need to supply a market that is not 100% served by the low supply that exists in the sale and distribution of bulk gas, since in the Lima region they only have 3 large suppliers: PETROPERÚ (Villa el Salvador), REPSOL (Ventanilla), LLAMAGAS (Independencia). Therefore, the objective of this research work is to demonstrate the viability of the MIGAS LIMA SA project in the search to develop a solid and constant sales and supply process for its portfolio of clients and potential buyers, creating efficiency and innovation from the main activities of its value chain, especially in the action plan of its logistics chain and innovating in the gas consumption control system and billing methods through an application that remotely manages these activities in interaction with the client. / Trabajo de investigación
36

Sensitivity Enhanced Long-Period Fiber Grating Based Photonic Devices for Biochemical Sensing

Yang, Jian 09 1900 (has links)
<p> Long-period fiber grating (LPG) sensors have been widely used as refractive index sensors due to their high sensitivity to the ambient refractive index change surrounding the fiber cladding of the LPG. Application of the LPG refractive index sensor has been found in chemical sensing and biochemical sensing, however for application of label-free dip and measure biosensors based on receptor immobilized LPG bio-sensor, the conventional fiber optic refractive index sensors are limited in the refractive index sensitivity, resolution, and operational range owing to the low sensitivity of the cladding mode effective index dependence on the ambient refractive index and the broad-spectrum feature of the LPG transmission spectrum. Low-cost, disposable fiber optic biochemical sensors with improved sensitivity, stability and resolution are needed to provide a high-sensitivity platform for immunology and DNA/aptamer biosensor. </p> <p> In this work, a novel fiber optic biosensing platform based on the LPG and the LPG in-fiber Michelson interferometer is designed and fabricated. The sensitivity and operation range enhancement is optimized by modifying the fiber cladding structure through reducing the cladding layer radius and applying a high-refractive index overlay with appropriate refractive index and thickness. The resolution of the refractive index sensor is improved by adopting the LPG in-fiber Michelson interferometer which turns the wide-spectrum feature of the LPG transmission spectrum into a narrow spectrum feature on the reflection spectrum of the interferometer. The reflection spectrum nature of the LPG in-fiber Michelson interferometer turns the sensor head into a single-end optotrode. The optotrode coated with bio-recognition film thus physically constitutes a short piece of fiber with one section of cladding reduced fiber. With single strand DNA (ssDNA) immobilized on the surface of the fiber cladding through biotin-avidin bridge, detection of the antisense DNA for the immobilized ssDNA is demonstrated. Immunoassay based on capture of target antigen by covalently immobilized antibody shows that reduction of the fiber cladding not only improve the sensitivity of the long period grating in-fiber Michelson interferometric biosensor but also improves the assay time. </p> / Thesis / Doctor of Philosophy (PhD)
37

Composite Films for Modifying Evanescent Wave Characteristics in Long-Period Grating Biosensors

Martin, Jennifer E. 17 February 2001 (has links)
Biosensors are detection devices that couple biological recognition elements to physiochemical transducers to generate quantifiable signals. Immunosensors are biosensors that use antibodies as the recognition element. The highly specific nature of antibody-antigen binding is exploited to create immunosensors that are sensitive to analytes in complex mixtures and demonstrate a rapid response. Fiber optical immunosensors based on long-period gratings have limited sensitivity at the refractive index of ordinary aqueous solutions (~1.33). A composite film was designed to raise the local refractive index of the sensor, thus increasing sensitivity. Titanium dioxide deposition raised the refractive index of the sensor to ~1.42. Bovine serum albumin was immobilized onto a dextran hydrogel and attached to the LPG element via reductive amination. The thickness of the hydrogel was estimated to be 500 nm using Environmental Scanning Electron Microscopy. The affinity film was probed by an evanescent wave to detect changes in refractive index due to the binding of anti-BSA IgG. Under these conditions, the sensor yielded a signal ratio of approximately 10-4 refractive index units per nm signal. Reproducible binding was shown over multiple exposures, with no cross reactivity for non-specific antibodies and other proteins. Anti-BSA IgG (20 µg/mL) in whole serum was recycled through the fiber holder with an accompanying peak wavelength shift that averaged 2 nm on an Optical Spectrum Analyzer with a noise level of 0.1 nm. The BSA affinity film was regenerated 50 times and showed a baseline shift of -1.3 nm. / Master of Science
38

Untersuchungen zur Prozessgasaufbereitung von Flüssiggas für die Dampfreformierung in Brennstoffzellen-BHKW

Anger, Stephan 11 December 2015 (has links)
Für PEM-Brennstoffzellen-Mikro-BHKW mit integrierter Dampfreformierung ist die Verwendung von LPG (Liquefied Petroleum Gas) bei fehlender Erdgasinfrastruktur interessant. Grundlage der BHKW-Effizienz ist eine optimale wärmetechnische Verschaltung, durch die u.a. das LPG/H2O-Gemisch effektiv auf die Reaktionstemperatur (700 °C) der Dampfreformierung vorgewärmt wird. In Abhängigkeit von der Verweilzeit, der das Gemisch ausgesetzt wird, können signifikante Mengen ungesättigter Kohlenwasserstoffe (C3H6, C2H4, C2H2) pyrolytisch gebildet werden, C3H6 kann des Weiteren bereits im LPG enthalten sein. Bei der katalytisch unterstützten Dampfreformierung fördert dies die Bildung verschiedenartiger kohlenstoffhaltiger Ablagerungen, wodurch eine vorzeitige Deaktivierung eintritt. In der Arbeit wird das Spaltpotenzial numerisch und experimentell untersucht. Durch Anwendung von Temperatur-Programmierter-Methanisierung und Ramanspektroskopie wird ferner der negative Einfluss bereits geringer C3H6-Anteile an einem Katalysator gezeigt. Aus den Ergebnissen werden abschließend Maßnahmen zur Minimierung kohlenstoffhaltiger Ablagerungen abgeleitet. / The use of LPG (Liquefied Petroleum Gas) is an alternative for PEM fuel cell micro-CHP systems with integrated steam reforming in the absence of natural gas infrastructure. An optimized thermo technical interconnection is the basis of the CHP efficiency, whereby, among other things, the LPG/H2O-mixture is preheated to the steam reforming reaction temperature (700 °C). Significant amounts of unsaturated hydrocarbons (C3H6, C2H4, C2H2) can be formed pyrolytically depending on the residence time for preheating the mixture; furthermore, C3H6 can be already a component of LPG. These species promote the formation of different carbon containing deposits on the reforming catalyst whereby a premature deactivation occurs. The thesis deals with the investigation of the pyrolysis potential using numerical as well as experimental methods. Furthermore, the negative effect of already low amounts of unsaturated hydrocarbons on a catalyst is shown by using Temperature-Programmed-Methanation and Raman spectroscopy. Finally, actions for avoiding the production of carbon containing deposits are derived from the results.
39

Risks Related to the Maritime Transportation of Oil and Gas (mainly Crude oil, LPG, and LNG) -A Conceptual Study and Empirical Outlook on the Baltic Sea and UK Territorial Waters to Mitigate Risks

Razmjooee, Yarmohammad January 2012 (has links)
Transportation of oil and gas by the Sea characterizes challenges from a safety viewpoint. In this type of transportation, different sizes of special tankers carrying oil and gas. The marine transportation of these scarce natural riches is involved with risks and hazards, which may lead to many losses; for instance, wasting oil and gas, injuries of people, damaging ships and properties, and damaging environment. The main purpose of this thesis is to evaluate the risks, hazards, and accidents during transportation of oil and gas (mainly Crude Oil, liquefied petroleum gas, and Liquefied natural gas) by the Sea with concentrating on transport safety. Hence, a better understanding of these risks and hazards can contribute to decrease of addressed losses.This study is carried out on risks associated with maritime transportation of oil and gas starting with describing the general casual chain (dealing with causes, incidents, accidents and consequences/causalities), continuing with describing risk analysis techniques (including event tree analysis and fault tree analysis) and risk control measures/options, and finally implementing aforesaid investigations on real data from two areas; namely UK territorial waters and the Baltic Sea.In this study, the results of analyzing data from 1991 to 2010 in UK territorial waters revealed that collision and grounding were two most common accidents in terms of crude oil tankers, LPG and LNG carriers in which 44% of all accidents were equally divided between collision and grounding. In this case, investigation on data from 2004 to 2010 in the Baltic Sea regarding tankers with cargo types of crude oil, oil, oil product and gases also repeated the same findings in that collision and grounding shared the biggest proportion of accidents with 50% and 34% respectively. Analysis of data in UK territorial waters provided that human factor was the main reason behind accidents with 46% followed by technical factor with 39%. Human factor and technical factor recognized also as the main causes of accidents in the Baltic Sea with 33% and 25% respectively. Regarding this subject, human error recognized as the chief culprit and failures in part of design &amp; construction was the second main initial causes of accidents in terms of both human and technical factors. The results of analyzing records from the Baltic Sea also provided that whilst human factor shared the biggest proportion of causes behind accidents, technical factor was the only cause of accidents contributing to all types of accidents. Findings are useful from safety outlook as if specifying accidents and causes of accidents during the Sea transportation of oil and gas. / Program: MSc in Industrial Engineering - Logistics Management
40

Développement d’un capteur à fibre optique à base de réseaux de Bragg superposés de courtes et de longues périodes : application à la mesure discriminée de température et de déformation / [Development of an optical fiber sensor based on superimposed fiber Bragg and long period gratings] : [application to the discriminate measurement of temperature and strain]

Triollet, Sébastien 03 December 2010 (has links)
[Les capteurs à fibres optiques présentent des qualités intéressantes en termes de tailles et de poids relativement faibles qui permettent de réduire l'intrusivité du capteur dans le matériau (ou dans la structure composite). Ils sont également insensibles aux perturbations électromagnétiques, stables et durables dans le temps, mais aussi sensibles à plusieurs sollicitations comme la température, la déformation et la pression, d'où un besoin essentiel de les discriminer. Parmi eux on distingue les réseaux de Bragg : ceux à courtes périodes (FBG : Fiber Bragg Grating) et ceux à longues périodes (LPG : Long Period Grating). Le travail de thèse reporté dans ce manuscrit, traite du développement d'un capteur à fibre optique basé sur la superposition d'un LPG et d'un FBG afin de mesurer et de discriminer la température et la déformation. De nombreuses approches sont proposées dans la littérature afin de découpler ces deux sollicitations cependant elles ne permettent pas forcément une utilisation en conditions réelles de mesures. C'est pourquoi nous introduisons la notion d'efficacité de découplage avec le paramètre E qui permet de comparer toutes ces approches et met en évidence un très bon potentiel pour la structure à base de réseaux superposés LPG/FBG. La mise en œuvre d'un tel composant est décrite dans ce manuscrit et consiste à inscrire initialement le LPG puis le FBG au même endroit et sur toute la longueur du LPG. De plus ce type de structure permet un multiplexage qui, bien que faible, est néanmoins possible. Les étalonnages en température et en déformation du capteur ont permis de mettre en évidence une erreur de l'ordre de 2% sur la sensibilité à la température et de 3% sur la sensibilité à la déformation, ce qui conduit à une erreur sur l'estimation de la température et de la déformation mesurée de l'ordre de 0.3°C et 3 microdef. Dans un souci applicatif, le capteur à base de réseaux de Bragg superposés est tout d'abord utilisé pour instrumenter une structure métallique soumise simultanément à une variation de température et de déformation. Les valeurs mesurées présentent une incertitude maximale de 0.4°C pour la température et de 3 me pour la déformation ce qui permet de valider notre composant pour le contrôle et la surveillance de structures métalliques. La seconde application étudiée est relative à l'instrumentation de pièces composites stratifiées de type verre/époxy pour le suivi de procédés d'élaboration par voie liquide : VARTM (Vacuum Assisted Resin Transfer Molding) et LRI (Liquid Resin Infusion), pour lesquels l'évolution de la température et de la déformation au cours du procédé est suivie par le capteur à base de réseaux de Bragg superposés LPG/FBG. Des mesures diélectriques (DEA) sont également réalisées au cours de ces procédés et permettent la comparaison et la validation de nos résultats] / [Optical Fibre Sensors present some interesting qualities when considering its size and weight relatively light, which lead to a low intrusivity of the sensor in a material (a composite structure). These sensors are insensitive to electromagnetic phenomenon, stable and long lasting with time, but sensitive to several solicitations such as temperature, strain and pressure hence a real need of discrimination. Among these sensors, we may discern the Bragg gratings: the Long Period Grating one (LPG) and the Fibre Bragg Grating (FBG) one. This thesis work reports the development of an optical fibre sensor based on two superimposed Bragg gratings: LPG and FBG for measuring and discriminating temperature and strain. Several studies are reported in literature without getting a real condition use. That's why we propose a parameter E, which stand for the discrimination efficiency leading to a possible comparison of the existing techniques and highlight the quite good potential of superimposed Bragg gratings. The settings of such a structure are given in this thesis report and consist in writing LPG first, then FBG over the entire length of the LPG, which also gives multiplexing possibilities. Strain and temperature calibration steps give sensitivities errors of 2% for temperature and 3% for strain, which lead to estimated errors on measured strain and temperature of 0.3°C and 3 microstrain respectively. In an application point of view, the sensor has been used for the instrumentation of a metallic structure subjected to a variation of temperature and strain applied simultaneously. The results exhibit a maximum error of 0.4°C and 3me for temperature and strain respectively, which is a good validation of the sensor for structural control and monitoring purpose. The second studied application is about instrumentation of glass/epoxy composite specimen for monitoring manufacturing processes: VARTM (Vacuum Assisted Resin Transfer Moulding) and LRI (Liquid Resin Infusion), for which temperature and strain have been monitored with the superimposed Bragg gratings based sensor. Dielectric analyses have also been performed during those processes in order to compare and validate our results]

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