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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.
61

IS THERE JUSTICE FOR SEXUAL TRAUMA? A STRUCTURAL MODEL TO EXAMINE FACTORS INFLUENCING POSTTRAUMATIC GROWTH AND DISTRESS

Fetty, Danielle Grace 01 May 2016 (has links)
The current study employed an exploratory approach to examine how specific sets of variables map onto a theoretical framework of posttraumatic growth (Schaefer & Moos, 1998). Specifically, the predictive capacity of belief in ultimate justice, optimism, and supportive relationships on outcomes of posttraumatic growth (PTG) and distress were examined, as mediated by supportive spirituality, meaning making, and problem solving. Secondarily, the factor structure and internal consistency of the English translation of the Belief in Immanent and Ultimate Justice Scale (BIUJS; Maes, 1998a, 1998b) was tested, which had yet to be used in the United States or with sexual assault survivors specifically. Archival data of 217 female survivors of sexual assault who completed an online survey as part of the author’s thesis were analyzed through structural equation modeling (SEM). The BIUJS, when applied specifically to sexual assault survivors, is best represented by a three-factor solution. The model hypothesized according to Schaefer and Moos’ (1998) theoretical framework was not supported by SEM results, and an alternate model emerged from analyses is presented to explain how worldview and appraisal/coping are related to posttraumatic growth and distress for sexual assault survivors. Survivors’ worldview (i.e., supportive spirituality, belief in ultimate justice, and belief in an immanently just world) indirectly predicted levels of PTG and distress. The relation between worldview and outcomes was significantly mediated by appraisal and coping (i.e., presence of meaning, optimism, supportive relationships, and problem solving). The current study adds to the literature and provides important directions for researchers and clinicians by demonstrating the important roles of worldview and appraisal/coping in facilitating growth, as well as the essential role of distress in healing.
62

Miniaturisation extrême de mémoires STT-MRAM : couche de stockage à anisotropie de forme perpendiculaire / Ultimate scalability of STT MRAM : storage layer with perpendicular shape anisotropy

Perrissin fabert, Nicolas 31 August 2018 (has links)
La plupart des efforts de développements actuels des STT-MRAM est centrée sur des jonctions tunnels magnétiques à aimantation hors du plan. Les derniers empilements mis au point utilisent avantageusement l’anisotropie perpendiculaire induite aux interfaces magnétiques métal / oxydes, qui permet de réconcilier la forte anisotropie demandée pour assurer une rétention suffisante de la mémoire ainsi qu’une faible densité de courant de retournement STT grâce au couplage spin-orbite faible. Cependant, pour des cellules mémoire de taille inférieure à 20 nm, il est difficile d’atteindre une rétention de 10 ans à 100°C en utilisant uniquement l’anisotropie interfaciale. Pour augmenter encore plus l’anisotropie magnétique, ceci impose l’utilisation de couches magnétiques de CoFeB ultraminces (épaisseur inférieure à 1.4nm) qui présentent un coefficient d’amortissement Gilbert augmenté ainsi qu’une magnétorésistance tunnel TMR réduite. Pour des nœuds technologiques inférieurs à 20 nm, des nouveaux matériaux présentant une forte anisotropie magnétocrystalline et faible coefficient d’amortissement doivent être trouvés. De plus, l’anisotropie interfaciale est très sensible aux propriétés structurelles et chimiques aux interfaces entre les métaux magnétiques et la barrière tunnel de MgO. Avec des techniques de nanofabrication conventionnelles, ces interfaces peuvent être endommagées durant notamment l’étape de gravure, ce qui conduit à une variabilité importante cellule à cellule. Pour résoudre ce genre de problèmes pour des cellules STT-MRAM de tailles très petites, nous proposons l’utilisation d’empilements jonctions tunnel magnétiques dans lesquels l’anisotropie de la couche de stockage est contrôlée uniquement par son anisotropie de forme hors du plan. Ceci donne notamment une couche de stockage de forme cylindrique avec un aspect de forme suffisamment large (épaisseur / diamètre environ > 1). De cette façon, pour des raisons purement magnétostatiques, l’aimantation de la couche de stockage sera orientée perpendiculairement au plan de la cellule. Dans cette approche, la géométrie planaire classique des couches minces est ainsi remplacée par une géométrie tridimensionnelle. Cette approche innovante a plusieurs avantages : (i) elle génère une source fiable et robuste d’anisotropie perpendiculaire, beaucoup moins sensible aux défauts de structure et aux fluctuations thermiques; (ii) permet d’utiliser des matériaux connus et facile à croître, avec des coefficients d’amortissement faible, comme le Permalloy, en combinaison avec du CoFeB aux interfaces avec la barrière tunnel de MgO et (iii) donne une approche miniaturisable, même à des diamètres sub-10 nm, car le même matériau peut être utilisé pour des nœuds technologiques très petits. / Most of the actual STT-MRAM development effort is nowadays focused on out-of-plane magnetized MTJ taking advantage of the perpendicular magnetic anisotropy (PMA) arising at magnetic metal/oxide interface. This interfacial anisotropy allows conciliating large anisotropy required to insure a sufficient retention of the memory together with low switching current density thanks to weak spin-orbit coupling. However this PMA is too weak to insure 10 year retention up to 100°C in sub-20 nm devices. For deeply sub-20 nm nodes, new materials with large bulk PMA and low damping still have to be found. Furthermore, because this PMA is an interfacial effect, it is very sensitive to the structural and chemical properties of the magnetic metal/MgO interfaces contributing to dot to dot variability. To solve these problems in very small feature size STT-MRAM, we propose a totally novel approach: use MTJ stacks in which the storage layer anisotropy is uniquely controlled by its out-of-plane shape anisotropy i.e. by giving the storage layer a cylindrical shape with large enough aspect ratio (thickness / diameter typically > 1). In such structure, for purely magnetostatic reasons, the storage layer magnetization lies out-of-plane. With this approach, the geometry of conventional 2D thin layers is thus replaced by a 3D geometry. This innovative approach had several advantages: (i) it creates a strong and robust source of perpendicular anisotropy, much less sensitive to interfacial defects and thermal fluctuations; (ii) allows the use of well-known materials with mastered growth and low magnetic damping, such as Permalloy in combination with FeCoB at the interface of the MgO tunnel barrier and (iii) yields to an extreme scalability of the memory point, down to the sub-10 nm node, as the same materials can be used at very low nodes.
63

Integrative transcending : mysticism beyond contact and experience

Dube, Christopher 06 1900 (has links)
This study explores an interpretation of mysticism as a way of life that is a response to what the mystic conceives of as ultimate reality. The suggestion is that what lies at the centre of reality is the sense of a dynamic non-dialectic absence/presence. Mysticism is suggested to be an exploration of this centre of reality that takes the form of a conjoined movement of transcending and integrating. The argument of the study is developed in light of the contemporary approach that has made mysticism either totally grounded in the mystic's socio-linguistic context (Steven T. Katz) or detached from it in a 'pure consciousness event' (Robert K. C. Forman et al), both of which are primarily driven by a focus on mysticism as an experience. What is judged to have been overlooked in the contemporary discussion is that which is argued as being most endemic to mysticism, that is, the explorative life-enactment of that which the mystic conceives of as ultimate reality. / Religious Studies and Arabic / M.A. (Religious Studies)
64

Jacinto, Fradique e Gonçalo: impasses oitocentistas sob o olhar do último Eça

Roberto Loureiro Junior 30 March 2009 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A fase conhecida como o último Eça é um período controvertido na obra de Eça de Queirós. A ilustre casa de Ramires (1900), A cidade e as Serras (1901) e A correspondência de Fradique Mendes (1900) são, geralmente, consideradas obras menores. Há quem veja em Gonçalo Ramires um personagem vazio; para outros, a saga de Jacinto é uma obra reacionária; e apenas Fradique Mendes desfruta de maior simpatia nos estudos queirosianos. No entanto, nos estudos mais recentes, há uma recuperação deste período e, para esses pesquisadores, tais obras apontam uma nova postura ideológica do autor que, através de elementos históricos, simbólicos e míticos, conduz a um diálogo com os temas e os valores mais discutidos da cultura européia naquele final de século. Com esses elementos, Eça expõe nas três obras a necessidade de a sociedade adotar uma postura de originalidade no pensar visando à independência intelectual e à eliminação de conceitos caducos. Assim, essas três obras são vistas neste trabalho como uma trilogia, e os três protagonistas representam três propostas de Eça de Queirós: Gonçalo é o português rural que busca no passado a força para mudar; Jacinto é o português cosmopolita que retorna às origens para, de modo singular, pôr-se em diálogo com o seu país e o mundo que conhecera na capital do século XIX (Paris); Fradique é o português global que circula à vontade pelos continentes, mas não deixa de amar Portugal. A trilogia apresenta propostas para um novo século: livrar o homem das amarras que o atavam ao nacionalismo romântico, à crença cega na ciência, ao poder da igreja e aos grandes sistemas filosóficos / The phase known as the ultimate Eça is a controversial period at Eça de Queiros opus. A ilustre Casa de Ramires (1900; translated as The illustrious House of Ramires), A cidade e as serras (1901; translated as The city and the mountains) and A correspondência de Fradique Mendes (1900; The Correspondence of Fradique Mendes) are usually considered minor texts. Some people see Gonçalo Ramires as an empty character; for others, Jacintos saga is a reactionary text; only Fradique Mendes relishes the affinity at queirosian studies. Nevertheless, at the most recent studies, there is a recovery of this period and, for this researchers, such books point out a new ideological position of the author that, through historical, symbolic and mythical elements leads to a dialogue with the themes and values discussed at the European culture at the end of the century. With these elements, Eça exposes in the three books the necessity of the society to adopt a position of original thoughts aiming at intellectual independence and the elimination of decrepit concepts. So, the three pieces are seen in this work as a trilogy and the protagonists represent the Eça de Queiross proposals: Gonçalo is the rural Portuguese that seeks for the strength to change in the past; Jacinto is the cosmopolitan Portuguese that returns to his origins to, in a single way, put himself in dialogue with his country and the world he knew in the capital of the 19th century (Paris); Fradique is the global Portuguese that easily circulates through the continents, still loving Portugal. The trilogy presents proposals to a new century: release man from chains that tie him to romantic nationalism, to the blind belief at science, to the power of church and to the great philosophical systems
65

Sintonia de controladores PID descentralizados baseada no método do ponto crítico

Campestrini, Lucíola January 2006 (has links)
Controladores PID são largamente utilizados no controle de processos industriais, tanto em sistemas monovariáveis como em sistemas multivariáveis. No entanto, muitos dos controladores encontrados na indústria são mal sintonizados. Um dos métodos mais simples de sintonia de controladores PID consiste em identificar algumas grandezas, as quais se relacionam com características do processo a controlar, e em seguida aplicar fórmulas para os parâmetros dos controladores baseadas nestas grandezas. Estas grandezas são o ganho e o período críticos do processo, os quais se relacionam diretamente com o limite de estabilidade do sistema. Uma característica bastante interessante deste método é que o mesmo pode facilmente ser implementado por um controle auto-ajustável. Por este fato, métodos de auto-ajuste destes controladores têm sido bastante utilizados em sistemas monovariáveis, através do uso do método do relé como procedimento de obtenção das grandezas críticas, necessárias à sintonia dos controladores. O método do relé consiste em aplicar um controle bang-bang em malha fechada com o processo do qual se quer identificar as grandezas críticas. Este procedimento, dentro de certas condições, provoca uma oscilação sustentada na saída do processo, da qual as grandezas críticas são obtidas. Tendo como objetivo o auto-ajuste de controladores PID em sistemas multivariáveis, o método do relé também pode ser utilizado para obtenção das grandezas críticas, devidamente adequado de maneira a obter as grandezas críticas multivariáveis do processo. Diferentes procedimentos de ensaios com relés podem ser aplicados em sistemas multivariáveis, porém somente um destes procedimentos é capaz de identificar as grandezas críticas multivariáveis do processo diretamente: o ensaio descentralizado com relés. Mesmo assim, a sintonia proposta na literatura é baseada nas fórmulas monovariáveis de Ziegler-Nichols e afins, mostrando-se, muitas vezes, inadequada. Desta forma, este trabalho tem o objetivo de apresentar um método de ajuste multivariável para controladores PID descentralizados, baseado nas grandezas críticas do processo. Este método estende o método do ponto crítico para sistemas monovariáveis aos sistemas multivariáveis, através da análise multivariável do problema. A análise do método do ponto crítico para sistemas monovariáveis mostra que um controlador PI ou PID sintonizado pelas fórmulas baseadas nas grandezas críticas do processo sempre irá deslocar o ponto crítico do processo para um outro ponto no plano complexo, determinado pelas fórmulas utilizadas. Da mesma forma, o método de sintonia proposto neste trabalho desloca o ponto crítico do processo para outro ponto no plano complexo, escolhido a priori, alterando a freqüência crítica do sistema. / PID controllers are widely used in process control, in singlevariable systems as well as in multivariable ones. Yet, many of the controllers found in industry are poorly tuned. One of the simplest tuning method of PID controllers consists in identifying some values which are related to the process characteristics, and simply apply some formulae based on these quantities to determine the parameters of the controllers. Theses quantities are the ultimate gain and the ultimate period of the process, which are directly related to the system stability limit. A very interesting characteristic of this method is that it is easily implemented by an auto-tuning control. Thus, auto-tuning methods of this kind of controllers have been largely used in singlevariable systems, using the relay feedback experiment in order to obtain the ultimate quantities, which are needed to tune the controllers. The relay feedback experiment consists in applying a bang-bang control to the process from which the ultimate quantities are to be identified. This procedure, under some conditions, provides a sustained oscillation in the process’ output, from which the ultimate quantities are obtained. Aiming at auto-tuning of PID controllers in multivariable systems, the relay feedback experiment can also be used in order to get the ultimate quantities. Different relay feedback procedures can be applied to multivariable processes, but only one of these can identify the real multivariable ultimate quantities, formally considering the multivariable nature of the process: the decentralized relay feedback (DRF). However, the tuning of the controllers proposed in the literature is based on Ziegler-Nichols like formulae, what seems to be, many times, inappropriate. This work presents a multivariable tuning method of decentralized PID controllers, based on the process’ ultimate quantities. This method extends the ultimate point method used in SISO systems to multivariable ones, through multivariable analysis of the problem. The analysis of the ultimate point method used in singlevariable systems shows that a PI or PID controller tuned through formulae based on the process’ ultimate quantities will always dislocate the ultimate point to another point in the complex plane, determined by the used formulae. The tuning method proposed in this work dislocates the process’ ultimate point of a multivariable process to another point in the complex plane, chosen a priori, modifying the system’s ultimate frequency.
66

Jacinto, Fradique e Gonçalo: impasses oitocentistas sob o olhar do último Eça

Roberto Loureiro Junior 30 March 2009 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A fase conhecida como o último Eça é um período controvertido na obra de Eça de Queirós. A ilustre casa de Ramires (1900), A cidade e as Serras (1901) e A correspondência de Fradique Mendes (1900) são, geralmente, consideradas obras menores. Há quem veja em Gonçalo Ramires um personagem vazio; para outros, a saga de Jacinto é uma obra reacionária; e apenas Fradique Mendes desfruta de maior simpatia nos estudos queirosianos. No entanto, nos estudos mais recentes, há uma recuperação deste período e, para esses pesquisadores, tais obras apontam uma nova postura ideológica do autor que, através de elementos históricos, simbólicos e míticos, conduz a um diálogo com os temas e os valores mais discutidos da cultura européia naquele final de século. Com esses elementos, Eça expõe nas três obras a necessidade de a sociedade adotar uma postura de originalidade no pensar visando à independência intelectual e à eliminação de conceitos caducos. Assim, essas três obras são vistas neste trabalho como uma trilogia, e os três protagonistas representam três propostas de Eça de Queirós: Gonçalo é o português rural que busca no passado a força para mudar; Jacinto é o português cosmopolita que retorna às origens para, de modo singular, pôr-se em diálogo com o seu país e o mundo que conhecera na capital do século XIX (Paris); Fradique é o português global que circula à vontade pelos continentes, mas não deixa de amar Portugal. A trilogia apresenta propostas para um novo século: livrar o homem das amarras que o atavam ao nacionalismo romântico, à crença cega na ciência, ao poder da igreja e aos grandes sistemas filosóficos / The phase known as the ultimate Eça is a controversial period at Eça de Queiros opus. A ilustre Casa de Ramires (1900; translated as The illustrious House of Ramires), A cidade e as serras (1901; translated as The city and the mountains) and A correspondência de Fradique Mendes (1900; The Correspondence of Fradique Mendes) are usually considered minor texts. Some people see Gonçalo Ramires as an empty character; for others, Jacintos saga is a reactionary text; only Fradique Mendes relishes the affinity at queirosian studies. Nevertheless, at the most recent studies, there is a recovery of this period and, for this researchers, such books point out a new ideological position of the author that, through historical, symbolic and mythical elements leads to a dialogue with the themes and values discussed at the European culture at the end of the century. With these elements, Eça exposes in the three books the necessity of the society to adopt a position of original thoughts aiming at intellectual independence and the elimination of decrepit concepts. So, the three pieces are seen in this work as a trilogy and the protagonists represent the Eça de Queiross proposals: Gonçalo is the rural Portuguese that seeks for the strength to change in the past; Jacinto is the cosmopolitan Portuguese that returns to his origins to, in a single way, put himself in dialogue with his country and the world he knew in the capital of the 19th century (Paris); Fradique is the global Portuguese that easily circulates through the continents, still loving Portugal. The trilogy presents proposals to a new century: release man from chains that tie him to romantic nationalism, to the blind belief at science, to the power of church and to the great philosophical systems
67

Sintonia de controladores PID descentralizados baseada no método do ponto crítico

Campestrini, Lucíola January 2006 (has links)
Controladores PID são largamente utilizados no controle de processos industriais, tanto em sistemas monovariáveis como em sistemas multivariáveis. No entanto, muitos dos controladores encontrados na indústria são mal sintonizados. Um dos métodos mais simples de sintonia de controladores PID consiste em identificar algumas grandezas, as quais se relacionam com características do processo a controlar, e em seguida aplicar fórmulas para os parâmetros dos controladores baseadas nestas grandezas. Estas grandezas são o ganho e o período críticos do processo, os quais se relacionam diretamente com o limite de estabilidade do sistema. Uma característica bastante interessante deste método é que o mesmo pode facilmente ser implementado por um controle auto-ajustável. Por este fato, métodos de auto-ajuste destes controladores têm sido bastante utilizados em sistemas monovariáveis, através do uso do método do relé como procedimento de obtenção das grandezas críticas, necessárias à sintonia dos controladores. O método do relé consiste em aplicar um controle bang-bang em malha fechada com o processo do qual se quer identificar as grandezas críticas. Este procedimento, dentro de certas condições, provoca uma oscilação sustentada na saída do processo, da qual as grandezas críticas são obtidas. Tendo como objetivo o auto-ajuste de controladores PID em sistemas multivariáveis, o método do relé também pode ser utilizado para obtenção das grandezas críticas, devidamente adequado de maneira a obter as grandezas críticas multivariáveis do processo. Diferentes procedimentos de ensaios com relés podem ser aplicados em sistemas multivariáveis, porém somente um destes procedimentos é capaz de identificar as grandezas críticas multivariáveis do processo diretamente: o ensaio descentralizado com relés. Mesmo assim, a sintonia proposta na literatura é baseada nas fórmulas monovariáveis de Ziegler-Nichols e afins, mostrando-se, muitas vezes, inadequada. Desta forma, este trabalho tem o objetivo de apresentar um método de ajuste multivariável para controladores PID descentralizados, baseado nas grandezas críticas do processo. Este método estende o método do ponto crítico para sistemas monovariáveis aos sistemas multivariáveis, através da análise multivariável do problema. A análise do método do ponto crítico para sistemas monovariáveis mostra que um controlador PI ou PID sintonizado pelas fórmulas baseadas nas grandezas críticas do processo sempre irá deslocar o ponto crítico do processo para um outro ponto no plano complexo, determinado pelas fórmulas utilizadas. Da mesma forma, o método de sintonia proposto neste trabalho desloca o ponto crítico do processo para outro ponto no plano complexo, escolhido a priori, alterando a freqüência crítica do sistema. / PID controllers are widely used in process control, in singlevariable systems as well as in multivariable ones. Yet, many of the controllers found in industry are poorly tuned. One of the simplest tuning method of PID controllers consists in identifying some values which are related to the process characteristics, and simply apply some formulae based on these quantities to determine the parameters of the controllers. Theses quantities are the ultimate gain and the ultimate period of the process, which are directly related to the system stability limit. A very interesting characteristic of this method is that it is easily implemented by an auto-tuning control. Thus, auto-tuning methods of this kind of controllers have been largely used in singlevariable systems, using the relay feedback experiment in order to obtain the ultimate quantities, which are needed to tune the controllers. The relay feedback experiment consists in applying a bang-bang control to the process from which the ultimate quantities are to be identified. This procedure, under some conditions, provides a sustained oscillation in the process’ output, from which the ultimate quantities are obtained. Aiming at auto-tuning of PID controllers in multivariable systems, the relay feedback experiment can also be used in order to get the ultimate quantities. Different relay feedback procedures can be applied to multivariable processes, but only one of these can identify the real multivariable ultimate quantities, formally considering the multivariable nature of the process: the decentralized relay feedback (DRF). However, the tuning of the controllers proposed in the literature is based on Ziegler-Nichols like formulae, what seems to be, many times, inappropriate. This work presents a multivariable tuning method of decentralized PID controllers, based on the process’ ultimate quantities. This method extends the ultimate point method used in SISO systems to multivariable ones, through multivariable analysis of the problem. The analysis of the ultimate point method used in singlevariable systems shows that a PI or PID controller tuned through formulae based on the process’ ultimate quantities will always dislocate the ultimate point to another point in the complex plane, determined by the used formulae. The tuning method proposed in this work dislocates the process’ ultimate point of a multivariable process to another point in the complex plane, chosen a priori, modifying the system’s ultimate frequency.
68

Análise de provas de carga estática em estacas pré-moldadas cravadas na cidade de Curitiba e região metropolitana / Analysis of static loading tests in concrete drive pile carried out in Curitiba city and metropolitan area

Ana Paula Fontana Vianna 29 June 2000 (has links)
Nesta dissertação são analisadas 34 provas de carga estática realizadas em estacas pré-moldadas de concreto, cravadas em diferentes locais da cidade de Curitiba e região metropolitana, sendo a maioria delas na Formação Guabirotuba. Três métodos de previsão da capacidade foram analisados: Aoki – Velloso (1975), Décourt – Quaresma (1978) e Amaral (1982, 1999). Para cada método foram propostos fatores de correção global e/ou parcial que tornam o valor da capacidade de carga mais próximo do valor da carga última obtida pelo critério de Van der Veen (1953). Com base em quatro provas de carga conduzidas até a ruptura, estudou-se a aplicabilidade do método de Van der Veen (1953) e determinou-se um critério para avaliar a extrapolação da curva carga x recalque em ensaios encerrados sem atingir a ruptura. Finalmente fez-se uma análise dos recalques comparando-se os valores medidos com os calculados, para três níveis de carregamento, além da comparação das curvas carga x recalque ajustadas com as experimentais. / This thesis presents the analysis of 34 static loading tests in concrete drive pile, located at different places of the Curitiba city and metropolitan area, in Guabirotuba Formation. Three methods of the bearing capacity prediction were assessed: Aoki – Velloso (1975), Décourt – Quaresma (1978) and Amaral (1982, 1999). For each method is proposed global correction factors and/or partial that turned the bearing capacity value close to the ultimate load obtained for the Van der Veen criteria (1953). Based on four static loading test carried out to failure, the applicability of the Van der Veen criteria was assessed and was determined a rule to evaluate the extrapolation of the load - settlement curve in tests stopped before of the failure. Finally, it was made an analysis of the settlements, where it was compared the observed values and the predicted values, for three loading level, and also a comparison between the experimental load-settlement curve and the predicted load-settlement curve.
69

Production, characterisation and economic validation of fuel pellets from Cassia Tora (Tafas in hausa language) for domestic and industrial applications

Aikawa, Ibrahim Usman January 2016 (has links)
A laboratory scale method was used to produce pellets from cassia tora stems with pelletizing temperature conditions of 30, 45, 60, 75, 90, 105 and 120oC under a pressure of 50, 70, 90,120 and 140 MPa. A total of 30 pellets were produced under each condition of production. The physical and chemical properties of the pellets were investigated. The pellets produced under 75oC and 90 MPa were found to have durability 90 %. A Bulk density range of 617 to 619 kgm-3 was measured for all the produced pellets irrespective of production conditions. The pellets produced in the range of 50 MPa/30oC-140 MPa/120oC were found to have a moisture content ranging between 7.18- 9.6 %. Ash content of 4.2 % was achieved using both Thermogravimetry (TGA) and CEN/TC 335 standard. The gross calorific value of the pellet was determined to be in the range of 17.89-18.1 MJ/kg. TGA results also indicates low moisture and ash content and the process of pyrolysis occurred at 137-550oC at 10oC/min heating rate. The activation energies and reactivities determined from TG/DTG curve are 72.01, 106.81 and 88.67 kJ/mol and 1.76 E+19, 5.1 E+06 and 3.92 E+05 for step I, II and III respectively. A water boiling experiment was carried out to evaluate the cooking efficiency of the pellets compared to fuel wood, kerosene and liquefied natural gas (LPG). The energy intensities and energy cost of 1.2, 0.78, 0.56 and 1.36 kJ/g of water and 0.2, 0.7, 0.4 and 0.2 Nigerian Naira (N) were calculated for fuel wood, kerosene, LPG and the pellets respectively. vii An economic analysis of fuel pellet production from Cassia tora stems has been carried out for conditions found in Kano state, Nigeria. The total production cost, for a base case scenario of 5t/h and operating for 270 days a year, is £4/tonne (1094.5 Naira/ton) of pellets. A ‘Willingness to pay’ analysis was also performed using the Contingent Valuation Technique. A structured contingent valuation questionnaire was administered to 420 randomly selected households in the Kano metropolis and Chi-square analysis was conducted on the data collected. The results of the analysis, at a 5 percent (0.05) confidence level, showed that p-values were less than 0.05 (0.05>p) for all the responded variables. It is confirmed, from the analysis, that an inadequate supply of energy is a statistically significant problem in Kano state and households significantly use fuel wood for domestic energy applications. The results also indicated the willingness of households to switch to a new product and were willing to pay a mean amount of £5 (1361.5 Naira) for a ton of the fuel pellets. Properties of the cassia tora pellets were found to be comparable with other biomass fuel pellets. It is recommended that policy and investment should be geared towards fuel pellet production in Nigeria, to address problems of energy poverty and environmental deterioration, and provide a means for further economic development.
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Possibilités d'amélioration de la qualité de viande chez le poulet par la sélection génétique et interactions avec le mode d'élevage / Possibility of improving broiler meat quality by genetic selection and interactions with rearing factors

Alnahhas, Nabeel 27 May 2016 (has links)
Dans un contexte où la demande mondiale en viande de poulet ne cesse d’augmenter, les qualités technologique et sensorielle de cette viande sont devenues un enjeu majeur pour l’industrie. L’analyse de deux lignées de poulet divergentes pour le pH ultime (pHu) du filet confirme que la génétique est un déterminant majeur de ce caractère. Leur comparaison montre qu’augmenter le pHu du filet par sélection impacte le pHu d’autres muscles et améliore de nombreux critères dont le pouvoir de rétention d’eau, le rendement technologique et la tendreté de la viande. Si l’histologie et la composition biochimique du muscle ne sont pas affectées par la sélection, nos résultats suggèrent un lien défavorable entre un trop faible niveau des réserves énergétiques musculaires et l’incidence de défauts structuraux telle que les striations blanches. Par contre, aucun antagonisme génétique entre le pH ultime et les caractères de production (poids vif, rendement en viande et indice de consommation) n’a été observé. / In a context where the global demand for chicken meat is increasing, technological and sensory qualities of this meat have become a major issue for the poultry industry. The analysis of two chicken lines divergent for ultimate pH (pHu) of breast fillets confirms that genetics is a major determinant of this trait. Between-lines comparison shows that increasing the pHu by selection changes the pHu of other muscles and improves many other quality criteria such as water-holding capacity, curing-cooking yield and meat tenderness. Although histology and biochemical composition of the muscle are not affected by the selection, our results suggest an unfavorable relationship between low muscle energy reserve and the incidence of structural defects such as white striping. On the contrary, no negative association between ultimate pH and production traits (body weight, meat yield and feed conversion ratio) was observed.

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