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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.
111

Preparation and properties of ultrafine magnetic particles

Wells, S. January 1989 (has links)
No description available.
112

Une approche géographique des parcs co-frontaliers entre les États-Unis et le Canada : politiques, coopérations et conflits : Les exemples des parcs nationaux de Glacier et des lacs Waterton, de Wrangell-Saint Elias et de Kluane, de North Cascades et des parcs provinciaux du lac Chilliwack et de la vallée de la Skagit / A geographical approach of co-border parks between the United-States and Canada : politics, cooperations and conflicts : Case studies of Glacier and Waterton Lakes, Wrangell-Saint Elias and Kluane and North Cascades National Parks and Chilliwack Lake and Skagit Valley Provincial Parks

Moumaneix, Caroline 23 November 2012 (has links)
Le premier parc national, Yellowstone, est né en 1872, aux États-Unis. Le Canada s’est inspiré puis éloigné de ce modèle. Les points communs entre ces deux pays sont nombreux : la wilderness, la conquête et la maîtrise du territoire, la création des premiers parcs, emblèmes identitaires forts. La comparaison des parcs co-frontaliers entre les États-Unis et le Canada souligne leurs apports réciproques. Compte-tenu de ces éléments, on devrait constater de réelles dynamiques de coopération, une proximité dans le zonage et la politique de gestion des parcs, une place similaire réservée aux populations locales et peu de conflits de part et d’autre de la plus longue frontière pacifique du monde. Cependant, notre étude, fondée sur des entretiens menés auprès des employés et des résidents des parcs et sur l’analyse de documents officiels, révèle des divergences entre ces parcs co-frontaliers. La wilderness et la frontière internationale sont perçues différemment. La réalité de la coopération transfrontalière ne correspond pas aux discours officiels. De multiples frontières internes fragmentent les parcs et affectent leur capacité à coopérer. Ces limites révèlent l’importance des populations locales, allochtones et autochtones, des associations, inégalement prises en compte par les autorités gestionnaires. Les enclaves privées dans les parcs américains conduisent à des conflits importants entre leurs propriétaires et le National Park Service. Au Canada, les tensions internes sont plus limitées. Au travers d’une volonté commune de protection de la wilderness, les parcs co-frontaliers affichent une coopération inégale et des fragmentations internes qui esquissent des régions bordières donnant une autre dimension à la frontière internationale.À partir d’un même modèle, le Canada et les États-Unis se différencient en matière de gestion, de coopération et d’implication des populations locales. Les États-Unis n’étant plus l’unique modèle en matière de parcs, le Canada se pose peut-être comme un modèle alternatif… / The first national park, Yellowstone, was created in 1872 in the United States. Canada was inspired by this model, before turning away from it. These two countries have many things in common: the wilderness, the conquest and control of territory, the creation of parks as strong markers of identity… A comparison of co-border parks between the US and Canada underlines their mutual contributions. Considering these facts, a real dynamic of cooperation should be observed: similar park zonings and management policies, a similar approach of local populations and very few conflicts on each side of the longest undefended borderline in the world. However, our study, based on interviews with both employees and inholders as well as on analysis of official documents, reveals divergences between these co-border parks. The wilderness and the international borderline are perceived differently. The reality of transboundary cooperation does not correspond to the official discourse. Numerous internal boundaries are fragmenting the parks and are thus affecting their capacity for cooperation. These limits reveal the importance of local populations, non-natives and natives, as well as associations that are considered unequally by park managers. The American parks inholdings lead to significant conflicts between the inholders and the National Park Service. In Canada, private property having been banned, internal tensions are more limited. Through a common will to protect wilderness, co-border parks show an unequal cooperation and internal fragmentations which outline border regions, giving another dimension to the international border. From an identical model, Canada and the United States are becoming differentiated in the matters of management, cooperation and the implication of the local populations. The US no longer being a unique model in the matter of parks, Canada may be rising as an alternative model…
113

Etude des mécanismes physico-chimiques impliqués dans la dévolatilisation et l’oxydation de combustibles solides pulvérisés sous atmosphères plus ou moins riches en oxygène / Study of physical-chemical mechanisms involved in pulverized fuels devolatilization and oxidation under oxygen enriched atmospheres

Bruhier, Cyril 06 December 2013 (has links)
Le charbon demeure à l’heure actuelle l’un des combustibles fossiles les plus couramment employés afin de produire de l’énergie. Son utilisation accrue dans le futur devra toutefois être conciliée avec la problématique de réduction des émissions de gaz à effet de serre. Des procédés permettant de limiter les émissions de CO2 ou de faciliter son captage, à l’image de l’oxycombustion, sont de fait actuellement développés. Leur implémentation à l’échelle industrielle implique toutefois de lever un certain nombre de verrous scientifiques liés à la compréhension des mécanismes physico-chimiques d’oxydation du charbon pulvérisé sous atmosphères plus ou moins riches en oxygène. Ce travail de thèse a de fait porté sur la mise au point d’un banc d’essais de laboratoire permettant d’étudier la combustion du charbon en reproduisant des conditions de chauffe analogues à celles rencontrées industriellement. Le brûleur hybride qui a été mis au point lors de ce travail a permis d’analyser des flammes jets de combustible solide sous atmosphères O2/N2 et O2/CO2 contenant des teneurs variables en oxygène. Une caractérisation détaillée des champs de vitesse et de température dans la chambre réactionnelle a été opérée. Des mesures de température des semi-cokes dans les flammes et de concentrations d’espèces gazeuses (CO, CO2, O2, NO, NOx et SOx) ont également été réalisées tout au long de la combustion. Des prélèvements de semi-cokes à différents temps de séjour ont enfin été opérés de sorte à obtenir des profils de dévolatilisation qui ont pu être confrontés à divers modèles empiriques issus de la littérature. L’ensemble des données que nous avons obtenues nous a permis de mettre en évidence l’impact d’un enrichissement en oxygène du milieu réactionnel sur les cinétiques de dévolatilisation et sur les mécanismes de formation de polluants tels que les NOx et les SOx. Les travaux menés sous oxycombustion ont pour leur part permis de mieux appréhender les différences fondamentales entre la combustion du charbon pulvérisé sous air et sous atmosphères O2/CO2. Pour terminer, des essais préliminaires de combustion de mélanges à base de charbon et de bois ont également été menés, la co-combustion de charbon et de biomasse constituant un autre moyen de limiter les quantités nettes de CO2 émises dans l’atmosphère. / Coal is currently one of the most widely used fossil-fuel for energy production applications. Its increasing use in the near future will have to face the greenhouse gas reduction objectives. Different processes have thus been developed to reduce CO2 emissions or ease their capture as oxy-fuel combustion for instance. The implementation of such techniques at industrial scale implies fundamental works to be undertaken to better understand the physical-chemical processes involved in the oxidation of pulverized coal under oxygen enriched environments. The present work has thus focused on the development of a lab-scale test bench allowing the study of coal combustion with heating rates similar to those met in industrial combustors. The hybrid burner that has been set up allowed the analysis of different solid fuels jet-flames under O2/N2 and O2/CO2 atmospheres containing various amounts of oxygen. A detailed characterization of the velocity and temperature fields has been carried out in the combustion chamber. Char temperatures and gaseous species concentrations (CO, CO2, O2, NO, NOx and SOx) have also been monitored during the combustion. Char samples at different residence times have finally been collected to derive devolatilization profiles that have been compared to simulated data issued from various empirical models from the literature. Obtained results clearly illustrate the impact of an oxygen enrichment of the reaction medium on devolatilization kinetics and pollutants formation including NOx and SOx. Works conducted in the fields of oxy-fuel combustion allowed to better understand the fundamental differences between pulverized coal combustion under air and O2/CO2 environment. Finally, preliminary experiments have been conducted using coal and wood blends since coal co-combustion with biomass appears to be another interesting mean to reduce net CO2 emissions into the atmosphere.
114

Optimisation of shrinkage in the design of compaction tooling for WC-Co

Blaski, Krzysztof 29 February 2008 (has links)
Abstract Tungsten carbide-cobalt powder is pressed before sintering into a compacted form using punches and a die cavity. After the powder has been pressed to a specific shape, it is sintered and shrinks a certain amount to a final size. To accommodate this shrinkage, the pressing tools are designed to a certain “shrinkage percentage” and thus the pressed component or compact is larger than the sintered component by that percentage amount. During the pressing process, there is a large amount of friction between the powder being compacted and the die cavity wall. To counter pressing friction, a lubricant is pre-mixed with the tungsten carbide powder. In the past at Powder Industries, the powder was mixed with wax and all of the tools were designed to a 20% shrinkage. In recent times, the wax in the powder has been replaced by PEG (polyethylene glycol) by most manufacturers as this increases the quality of the final product and is easier to remove in the furnaces. As a result of the new PEG lubricant, the tool wear rate at Powder Industries increased and because a higher pressure had been necessary to achieve powder pressing to the same shape and form, often the pressed components exhibited cracks or were not pressed ideally. On account of the problems introduced by PEG, correct tool design for the shrinkage was obtained by a ‘trial & error’ process. This project has been motivated by the need of establishing pressing and/or design ‘rules’ that would do away with trial and error when designing compaction tooling. The project has consisted of investigating the physical properties of 23 grades of WC-Co powder (with or without TiC and TaC) and of performing a series of pressing tests for each grade. A relationship between the apparent density of a powder and the ideal green density of the green compact pressed from the same powder has been found. Using this relationship, an equation has been derived between ideal shrinkage, powder apparent density, component sintered density and powder volatile content. Since the last three parameters are known to the tool designer, this equation can be used to calculate the ideal shrinkage when designing new compaction tooling. This method of calculating shrinkage is now in general use at Powder Industries and many successful sets of compaction tooling have already been manufactured
115

Is there a mortality differential by marital status among women in South Africa? a study on a rural sub-district of Mpumalanga Province in the North-East South Africa

Shoko, Mercy 22 September 2009 (has links)
Abstract Using longitudinal data collected between 1999 and 2007, for Agincourt Demographic Surveillance Area, the paper examines the effect of marital status and co-residence on mortality of women who are aged between 20 and 80. The Cox Proportional Hazard Model is used to investigate the relationship between mortality and the covariates; marital status, co-residence, woman’s country of origin and marital duration for married women. The number of months the husband was resident in the ADSA is used as a proxy for coresidence. After controlling for women migration, marital status and co-residence were significant. The divorced/separated and widowed women had a higher probability of dying compared to the married. In addition, being married to a migrant partner increased the woman’s probability of dying. Thus the study concludes that marital status and coresidence affects mortality.
116

Co-writes : En studie av den musikaliska processen i låtskrivning tillsammans med andra.

Wallentén, Siri January 2018 (has links)
Att skriva musik med andra personer påverkar mig både som musiker, låtskrivare och personligt. Efter ett samtal med producenten och låtskrivaren Max Thulin föddes en nyfikenhet i mig kring låtskrivning med andra personer, både okända och för mig kända personer. Jag ville genom mitt arbete undersöka hur den musikaliska processen påverkades av vem jag skrev med och vad det skulle få för effekter på mitt initiativtagande, textförfattande, melodiskrivande och producerande av en låt. Jag har i mitt arbete skrivit musik tillsammans med fyra andra musiker, två vänner och två för mig okända personer. Låtskrivningssessionerna har varit under begränsad tid och allt material har skapats på plats under sessionerna. Arbetet har resulterat i fyra låtar av olika karaktär och genre. Efter genomlyssning och analysering av låtskrivningssessionerna kan jag dra slutsatsen att mitt musikaliska initiativtagande påverkas starkt av vem jag skriver med. Jag har fått utveckla nya verktyg och tankebanor för att bland annat arbeta med textförfattande tillsammans med en annan låtskrivare, jobba med stämföring där två röster ska sjunga parallellt och bli medveten i vilka musikaliska val jag väljer att ta under en låtskrivningssession.
117

Pais que retornam a residir com os filhos na velhice: novas ou velhas parcerias?

Santos, Valeria Lima Antunes dos 07 April 2005 (has links)
Made available in DSpace on 2016-04-26T18:16:01Z (GMT). No. of bitstreams: 1 Pais que retornam a residir com os filhos.pdf: 331608 bytes, checksum: c2a87624be49139ad49c47ca423304f8 (MD5) Previous issue date: 2005-04-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increase in longevity in Brazil has repercussions on all the social layers; there has been a growing concern about aging. Medical sciences and technology have been offering a better quality of life to the aging being. However, how can one live these extra years with dignity, having their rights guaranteed? In our society, the family still is the link between the individual and the community in which this subject is inserted. Therefore, it is the main spring that launches the subject to life. Consequently, it is responsible for the being that is formed. It is necessary to think about the cares that are the responsibility of that institution towards its older members, when these affective bonds remain strong. The present work aimed to investigate how the elderly person perceives the family institution nowadays, how he relates to the different generations, what difficulties he encounters in this relationship, and how he organizes himself internally before the contradictions. To achieve this, the qualitative analysis allowed to understand, through the look of this old subject, how he faces this new transition period and the way in which he continues the life projects that had been postponed. It was possible to identify an increasing commitment of this age segment to taking into their own hands the success for achieving what they consider significant. Although living with the family, the elderly person demonstrates that he preserves the autonomy and responsibility for his choices. / O aumento da longevidade no Brasil repercute em todas as camadas sociais; há uma crescente preocupação diante do envelhecer. As ciências médicas e a tecnologia vêm proporcionando ao ser que envelhece maior qualidade de vida. Mas, como viver estes anos a mais, com dignidade e ter os direitos garantidos? Em nossa sociedade, a família ainda é o elo entre o indivíduo e a comunidade na qual esse sujeito se insere. Portanto, é a mola mestra que lança o sujeito para a vida. Conseqüentemente, é responsável pelo ser que se forma. Há que se pensar a respeito dos cuidados que cabem a essa instituição, para com os seus membros mais velhos, quando esses vínculos afetivos permanecem fortes. O trabalho aqui realizado procurou conhecer como o idoso percebe a instituição família na atualidade, como se relaciona com as diferentes gerações, quais são as dificuldades nesse convívio e como se organiza internamente diante das contradições. Para tanto, a análise qualitativa permitiu, mediante o olhar desse sujeito velho, compreender como enfrenta esse novo período de transição e a maneira como dá continuidade aos projetos de vida que foram postergados. Foi possível identificar um crescente comprometimento desse segmento etário em tomar para si a conquista do que considera significativo. Mesmo residindo com a família, demonstra que preserva a autonomia e a responsabilidade por suas escolhas.
118

Epidemiology of infections and co-infections : impact on survival and growth of zebu cattle under one year

Mwangi, Samuel Thumbi January 2012 (has links)
In any host population, individuals may be infected with multiple pathogens concurrently or in sequence. The direction and strength of pathogen-pathogen interactions are often unknown and dependent on the mechanism of interaction. This thesis is concerned with the epidemiology of infections and coinfections in zebu cattle during their first year of life, and the consequences they have for hosts’ survival probabilities and growth rates. Specifically, the study aims to: a) identify the many different pathogen infections occurring in zebu cattle under one year old, b) identify the main causes of mortality and reduced growth rates, c) test for evidence of effects of pathogen-pathogen interactions on mortality and growth, and d) determine the risk factors for infections with pathogens associated with increased mortality and reduced growth rates in zebu calves. To achieve these aims data collected from an epidemiological follow-up study of a cohort of 548 indigenous zebu cattle, recruited at birth and followed for the entire first year of life was used. Growth rates were enormously variable (52 to 704% of birth-weight) and 88 (16%) of the calves died during the first year, most from infectious disease. In total, 25,104 calf weeks of observation and data from 5,337 individual calf visits were analysed. Over 50 different pathogens were identified in the cohort. The thesis begins by providing an overview of zebu cattle and the importance of cattle diseases relevant to Sub-Saharan Africa, emphasising the importance of epidemiological studies taking into account co-infections, which are common in the natural populations, as opposed to a single-pathogen focus. A detailed description of the study design, data collection and descriptive analysis of non-infectious factors, including management and environmental factors, and a descriptive analysis of all pathogens screened for in the study are provided. Using Cox proportional models with frailty terms, the study then identifies infectious and non-infectious risk factors associated with mortality. Further, the role co-infections play in decreasing survival probabilities are investigated, revealing that the hazard for death from East Coast Fever (ECF) - the single most important disease associated with 40% of all deaths - increases 10 times in animals co-infected with Trypanosoma species, and 1.3 times for every 1000 eggs per gram faeces increase in strongyle egg count. Mixed-effect models are used to study growth rates and the impact of coinfections, revealing both synergistic interactions (lower host growth rates) of T. parva and A. marginale co-infections, and antagonistic interactions (relatively higher host growth rates) of T. parva and T. mutans co-infections compared to single infections with T. parva. Further, this work shows that helminth infections can have a strong negative effect on the growth rates but this is burden-dependent. These findings provide baseline epidemiological data on the diseases with greatest impact on health and performance of young zebu cattle, information that is valuable in the prioritisation and control of diseases. Additionally, they provide evidence of co-infections affecting host growth and survival, and have important implications on disease control strategies, suggesting benefits of aan integrated approach to control of worm, tick and tsetse-borne diseases.
119

Engagement du consommateur dans la co-création de valeur : rôle des motivations et conséquences sur l'empowerment psychologique, la satisfaction et le bien-être subjectif / Consumer engagement in value co-creation : role of motivations and consequences on psychological emporwerment, satisfaction and subjective well-being

Thion, Stéphane 03 April 2018 (has links)
Dans un contexte de forte compétition et d’accélération des processus d’innovation, la co-création de valeur entre l’entreprise et les consommateurs devient un avantage compétitif. Encore faut-il que le consommateur accepte de s’engager dans les interactions qui sous-tendent cette co-création de valeur. Pourquoi les consommateurs sont-ils prêts à s’engager dans la co-création de valeur ? Quelles sont les conséquences de cet engagement ? Trois études quantitatives ont été menées afin de répondre à cette problématique. Cette recherche contribue à la littérature en révélant plusieurs mécanismes : la motivation intrinsèque (plaisir d’interagir) et la motivation extrinsèque introjectée (implication de l’ego) sont les principaux moteurs de l’engagement dans des interactions co-créatrices de valeur alors que la motivation extrinsèque internalisée (sentiment de compétence) renforce la motivation intrinsèque. Cet engagement a un effet positif sur l’empowerment psychologique du consommateur. De façon surprenante, l’effet de cet engagement sur le bien-être subjectif du consommateur dépend du produit utilisé. Ces résultats contribuent à donner aux managers marketing des leviers d’actions qui leur permettront d’améliorer leur connaissance des usages afin d’adapter leur offre et innover. / In a context of strong competition and acceleration of innovation processes, value co-creation between the company and consumers becomes a competitive advantage. However, the consumer must still agree to engage in the interactions underlying value co-creation. Why are consumers willing to engage in value co-creation? What are the consequences of such engagement? Three quantitative studies were conducted to address this issue. This research contributes to the literature by revealing several mechanisms: intrinsic motivation (pleasure of interacting) and introjected extrinsic motivation (ego involvement) are the main drivers of engagement in value co-creating interactions while internalized extrinsic motivation (feeling of competence) reinforces intrinsic motivation. This engagement has a positive effect on consumer’s psychological empowerment. Surprisingly, the effect of this engagement on their subjective well-being depends on the product used. These results contribute to give levers for action to marketing managers that will improve their knowledge of uses in order to adapt their offer and innovate.
120

Skrivsamarbete och produktion av elektroniska dokument i studiesammanhang / Collaborative writing and production of electronic documents in a study context

Palmquist, Jonas January 2009 (has links)
<p>This thesis paper presents experiences and views on collaborative writing from interviews with university students. Analysis of these interviews, focusing on problems with coordination and technological tools,  shows that problems to some extent can be avoided with knowledge of the tools used and knowledge of coordination.</p>

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