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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

Heat waste recovery system from exhaust gas of diesel engine to a reciprocal steam engine

Duong, Tai Anh 05 October 2011 (has links)
This research project was about the combined organic Rankine cycle which extracted energy from the exhaust gas of a diesel engine. There was a study about significant properties of suitable working fluids. The chosen working fluid, R134a, was used to operate at the dry condition when it exited the steam piston engine. Furthermore, R134a is environmentally friendly with low environmental impact. It was also compatible with sealing materials. There were calibrations for the components of the combined Rankine cycle. The efficiency of the heat exchanger converting exhaust heat from the diesel engine to vaporize R134a was 89%. The average efficiency of the generator was 50%. The hydraulic pump used for the combined Rankine cycle showed a transporting problem, as vapor-lock occurred when the pump ran for about 1 minute. The output of the combined Rankine cycle was normalized to compensate for the parasitic losses of a virtual vane pump used in hydraulic systems for the 6 liter diesel engines. There were three different vane pump widths from different pumps to compare frictional loss. The pump with the smallest vane width presented the least frictional mean effective pressure (fmep) (0.26 kPa) when scaled with the displacement of the GMC Sierra 6 liter diesel engine. The power output of the Rankine cycle was scaled to brake mean effective pressure (bmep) to compare with the frictional mean effective pressure. The maximum bmep was at 0.071 kPa when diesel engine had rotational speed at 2190 RPM. The power outputs of the organic Rankine compensated partially the frictional loss of the vane pumps in the 6 liter diesel engine. By using R134a, the condensing pressure was 0.8 MPa; hence, the power outputs from steam engine were limited. Therefore, refrigerants with lower condensing pressure were needed. There were proposal for improvement of the organic Rankine by substituting R134a by R123 (0.1 MPa), R21 (0.2 MPa), and R114 (0.25 MPa) . / text
62

Harsh or inept parenting, youth characteristics and later adjustment

Pakalniskiene, Vilmante January 2008 (has links)
Despite most parents’ good intentions to provide a warm, supportive environment in which the child can grow and develop socially appropriate behavior, they might occasionally act toward their child in a negative or even harsh way. Some do this more consistently than others. This dissertation examined the relationships between harsh or inept parenting and children’s characteristics in predicting various adjustment problems. The first aim of the dissertation was to examine if experienced harsh parental behavior is associated with adjustment problems for children from different cultures in a similar way. Study I showed that the effects of harsh parenting were very similar for children from different countries, but the magnitude of these effects differed. The second aim was to examine how parents and youths respond to each other over time. Studies II and III showed that youth characteristics influenced harsh or inept parenting and, to a lesser extent, parents’ behaviors could affect youth characteristics or behavior problems. The third aim of this dissertation concerns the role of child or youth characteristics in the link between harsh parenting and adjustment problems. Findings from Study II suggested that, youth characteristics might be responsible for both harsh parenting and problematic peer relationships, thus explaining the link between them. Studies IV and V showed that children’s early unmanageability increased the risk of having more adjustment problems later in life only for some children. The fourth aim was to examine how the early characteristics of children who experience physical punishment in the context of parenting behaviors that communicate negative emotions affect later adjustment. The findings from Studies IV and V suggest that only for some children, those who experience certain combinations of harsh parental behavior, is early unmanageability a risk factor for social adjustment problems. Overall, the studies in this dissertation provide insights into the roles of harsh or inept parenting and youth characteristics in the development of various adjustment problems. Even though parents’ negative behaviors may affect youth social adjustment, youth characteristics and behaviors can strongly contribute to their own adjustment and to harsh or inept parenting.
63

EVIDENCE FOR LOCAL ADAPTATION IN BIRDS

ROHWER, VANYA 28 September 2010 (has links)
Phenotypic traits that vary geographically within species are commonly assumed to represent local adaptations to different environments. In order for local adaptation to evolve by natural selection, three conditions must be met: (1) traits must vary geographically, (2) local variants of traits must provide a fitness advantage (increased survival or reproductive success) within the local environment, and (3) local variants of traits must be heritable. In chapter two, we review evidence for local adaptation in birds. Geographic variation among populations is nearly ubiquitous, yet experimental tests of the fitness advantages of local trait variants are rare among populations of birds, presumably because of the difficulties in transporting individuals between populations. Thirty-seven studies have tested the heritability of among population variation in traits. Thirty-three of the 37 studies found some degree of heritability of variation among populations, consistent with traits diverging in response to natural selection. In chapter three, we experimentally test the fitness consequences of divergent nest morphologies of Yellow Warblers (Dendroica petechia) using reciprocal nest transplant experiments between a temperate and subarctic site in Canada. Yellow Warblers breeding at our subarctic site build larger nests constructed with more insulative materials than Yellow Warblers breeding at our temperate site, and these differences are the result of different nest building behaviours. Temperate nests transplanted to subarctic sites experienced significantly colder temperatures, and tended to suffer higher egg and nestling mortality due to climatic conditions (cold temperatures), than locally transplanted subarctic nests. Adult females breeding in subarctic sites that received temperate nests changed their incubation behaviours by taking shorter recesses than females who received locally transplanted subarctic nests. In contrast, subarctic nests transplanted to our temperate site showed no changes in nest temperature, fledgling success, or parental behaviour during incubation. We suggest that divergent selective pressures acting on Yellow Warblers in subarctic and temperate environments results in different nest building behaviours. Cold temperatures in our subarctic site likely favour increased investment in larger, insulative nests, whereas warmer temperatures at our temperate sites likely favour reduced investment in nest building, and consequently smaller nests. / Thesis (Master, Biology) -- Queen's University, 2010-09-28 13:16:38.686
64

Thermophoresis in colloidal suspensions

Burelbach, Jérôme January 2018 (has links)
This dissertation examines the motion of colloids in a temperature gradient, a non-equilibrium phenomenon also known as thermophoresis. Chapter 1 gives an introduction to the existing applications and basic concepts of thermophoresis and outlines some of the experimental and theoretical challenges that serve as a motivation for this PhD project. In Chapter 2, a general theoretical description for thermophoresis is formulated using the theory of non-equilibrium thermodynamics. The colloidal flux is split up into an interfacial single-colloid contribution and a bulk contribution, followed by a determination of transport coefficients based on Onsager’s reciprocal relations. It is further shown how the phenomenological expression of the thermophoretic flux can be recovered when the fluid is at steady-state. The results issuing from this description are then discussed and compared to other existing approaches, some of which are shown to neglect the hydrodynamic character of colloidal thermophoresis. Chapter 3 is dedicated to the validation of the introduced theoretical framework by means of computer simulations, using a simulation technique known as multi-particle collision dynamics. More specifically, the dependence of the thermophoretic force on different system parameters is examined and deviations from the theoretical prediction are explained by an advective distortion of interfacial fluid properties at the colloidal surface. Chapter 4 presents steady-state measurements of functionalised colloids in a temperature gradient, showing how the addition of molecular surface groups increases the experimental complexity of thermophoretic motion. The relaxation process behind this steady-state is also studied, to determine how the relaxation speed depends on the applied temperature gradient. In chapter 5, a general conclusion is drawn from the presented work and its implications are briefly discussed in relation to the current state of knowledge. Finally, the discussion is closed with an outlook on remaining challenges in understanding colloidal motion that could be the subject of future research.
65

Reciprocal undervisning - en studie om lässtrategier och deras betydelser

Dirani, John, Doganson, Eveline January 2018 (has links)
One of the many core aspects of learning a language involves reading comprehension. Being able to not only read but understand and decipher the context of content is one of the many factors that are essential in order to fully comprehend a subject. Reading comprehension is this assignments main focus and we have delved into this category through a literature study.For this literature study, we have analyzed the research of multiple different theses as well as scientific articles. Various different studies have been made regarding reading comprehension. We however, have decided to primarily engage in the reading strategies that were originally formed by Palincsar and Brown. The research in which these two authors elaborated on a reading strategy called reciprocal teaching. The content of this assignment discusses the meaning of reciprocal teaching, its' benefits as well as the disadvantages of using the strategy.The reason why this reading comprehension strategy originated lies within the fact that many students were lacking in understanding what they were reading. This became an evident issue that had to be addressed as school results were gradually decreasing. As reciprocal teaching became some sort of phenomena, many countries wanted to implement the strategy into their schools - this includes Sweden.Throughout the many years in which the strategy has been used in schools all over the world, statistics have shown that reciprocal teaching is a valid method for increased knowledge in reading comprehension. In Swedish institutional schools, reciprocal teaching is being used on a daily basis. It has however translated and expanded itself into what is being called "läsfixarna" which this assignment will also discuss. The results show that reciprocal teaching is a fundamentally working strategy that has proven to improve reading comprehension.
66

Optimisation d'un isolateur coplanaire à déplacement de champ et ondes magnétostatiques opérant en bande X / Optimization of an isolator coplanar field displacement and waves magnetostatic operating in X-band

Ouzer Nabil, Adam 27 May 2016 (has links)
Optimisation d’un isolateur coplanaire à déplacement de champ et ondes magnétostatiques opérant en bande X. Résumé en français non fourni / Optimization of an isolator coplanar field displacement and waves magnetostatic operating in X-band. English abstract not supplied
67

Understanding the lives and labours of lone-mother students

Nawaz, Sajida January 2016 (has links)
This study has explored the experiences of lone mothers and their labours as lone- mother students in Higher Education and en route to accessing Higher Education. The main aim of the study was to investigate barriers and constraints in provision of support for lone mothers wishing to study in Higher Education. The importance of education for lone parents has been well documented (Fryer, 1997; Scottish Office,1998; Powney et al., 2000), and there has been a plethora of research undertaken on Higher Education. However, the connection between the lone mother and education has not received much attention; little is known about the support that is offered to lone mothers whilst accessing Higher Education. Research by the National Union of Students (NUS) (2009) has shown that in many ways the responsibilities of mothering and mothers have not been considered by educational institutions as many courses operate in a climate of assumption that most students are free from family obligations of providing care. Due to lack of empirical research undertaken in this area, this study adopted a qualitative ethnographic approach to investigate the lives of lone-mother students. Furthermore, the study was conducted by an international student from Pakistan who is a lone mother herself and whose experiences also form a part of this research. An ethnographic approach was adopted and developed, to enable a holistic understanding of the lone mothers’ experience in Higher Education and specifically in relation to their cultural background. Hence, in-depth, semi-structured interviews were opted for to collect data. The research revealed in-depth knowledge about the relationships that the lone mothers share with their children, extended family, friends and with studies. The data suggested the need for socio - economic support for lone mothers in Higher Education. The qualitative inquiry method used in this study allowed for an examination of the phenomenon of ‘lone motherhood’. The depth, range and longitudinal nature of the data allowed to see contradictions or contrasts in the data (e.g. extrinsic/intrinsic motivations), as well as changes and developments over time (anxiety/self-esteem). The iterative approach also enabled emerging theories and concepts to develop and to be tested over time (e.g. ‘modelling’, ‘utopian’ narratives). Thus, the ethnographic approach enriched the possibilities of ‘grounded’ theorising, and also improved the possibilities of extending previous studies. Thus it indicates that lone-mother students’experiences of education are complex and therefore it is argued that the study of lone- mother students should be extended to conduct further research into different aspects of lone mother students in Higher Education.
68

A via excêntrica: Hölderlin e o projeto de uma nova estética / The eccentric path: Hölderlin and the project for a new aeshtetics

Ulisses Razzante Vaccari 30 March 2012 (has links)
A presente tese procura expor as linhas gerais do projeto estético de Hölderlin, tal como ele procurou realizá-lo entre 1793 e 1797. Anunciado em diversas cartas como uma tentativa de encontrar o princípio esclarecedor das oposições do espírito, tais como natureza e liberdade, sujeito e objeto, eu e não-eu, esse projeto estético toma por base a relação entre filosofia e poesia tal como a estabeleceu Kant na Crítica da Faculdade de Julgar, em especial na seção em que trata das ideias estéticas, da imaginação produtiva e do gênio, bem como aquela estabelecedia por Schiller em Sobre graça e dignidade, na medida em que este último procura fundar uma estética objetiva a partir dos esforços iniciados por Kant nesse mesmo sentido. Mas é principalmente ao entrar em contato com a filosofia da Doutrina-da-ciência, de Fichte, que Hölderlin vislumbra todo o potencial dessa relação entre filosofia e poesia. Em sua obra, afinal, Fichte atribui à imaginação criadora um papel ainda mais importante do que Kant, na medida em que, para aquele, a imaginação constitui a origem das separações encontradas no eu. O fato, porém, de que Hölderlin não realiza sua anunciada estética na forma teórica não impede de vê-la executada poeticamente em seu romance de formação Hipérion ou o eremita na Grécia. Assim como o filósofo da Doutrina-da-ciência reduz as oposições encontradas no eu à imaginação por meio do método da determinação recíproca, também Hipérion, na medida em que realiza a passagem da natureza para o âmbito da liberdade e da poesia, é capaz de unificar as oposições próprias da via excêntrica. / This thesis is intended to render an outline of the aesthetic project Hölderlin sought to carry out between 1793 and 1797. His aesthetic project, which in a number of letters he addressed as an attempt to find the principle enlightening such oppositions of spirit as nature and freedom, subject and object, self and not-self, is based upon the philosophy-poetry relationship as established by Kant in the Kritik der Urteilskraft, especially in the section dealing with aesthetic ideas, productive imagination, and genius, as well as the one Schiller establishes in Über Anmut und Würde to the extent he succeeds in founding an objective Aesthetics upon Kant\'s efforts to this effect. However, it was not before he got in touch with Fichte´s Wissenschaftslehre philosophy that Hölderlin realizes the entire potential of this philosophy-poetry relationship. After all, throughout his work Fichte assigns creative imagination a more important role than Kant does, as imagination, for the former, is the origin of the separations residing in the self. Hölderlin\'s failure to perform his announced Aesthetics in the form of theory, however, did not prevent him from accomplishing it poetically in his novel Hyperion or the Hermit in Greece. Just as the philosopher of the Wissenschaftslehre reduces unto imagination the oppositions in the self using the reciprocal determination method, Hyperion is also capable of unifying the oppositions pertaining to the eccentric path as it leads from nature into the realm of freedom and poetry.
69

Biologia reprodutiva de espécies de Chamaecrista Moench. (Fabaceae – Caesalpinioideae) em uma área de restinga de Pernambuco

ALMEIDA, Natan Messias de 14 February 2011 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-06-29T15:21:51Z No. of bitstreams: 1 Natan Messias de Almeida (1).pdf: 1218891 bytes, checksum: 767309899ce757df7cd7cada685600f0 (MD5) / Made available in DSpace on 2016-06-29T15:21:51Z (GMT). No. of bitstreams: 1 Natan Messias de Almeida (1).pdf: 1218891 bytes, checksum: 767309899ce757df7cd7cada685600f0 (MD5) Previous issue date: 2011-02-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Enantiostyly is a floral polymorphism that includes reciprocal hercogamy, resulting in flowers that form mirror images. One floral morph present sexual elements positioned at the right side of the flower and the other morph present these elements turned to the left. This mechanism is interpreted as a strategy that maximizes cross pollination. Many species of the genus Chamaecrista have been recorded as monomorphic enantiostylous, then, present two floral morphs in the same individual. Considering that the genus is very common in restinga vegetation, that is an extremely altered ecosystem, and the lack of knowledge in relation to several aspects of enantiostyly, the aim of this study is to investigate the reproductive biology of two Chamaecrista species in an area of restinga vegetation of Pernambuco state, Brazil, focusing aspects of enantiostyly. The first chapter includes the investigation of the functioning of enantiostyly in C. ramosa through data on floral biology, floral visitors’ behavior, breeding system and other aspects related to the reproductive biology. This species presented patterns of pollen deposition and capture that are typical of enantiostylous species described by other studies. It is self-compatible, being visited exclusively by bees. The second chapter reports the enantiostyly in C. flexuosa, including morphological, morphometric and reproductive aspects. Taking into account only the floral morphology, the species presents two floral morphs (left and right), but when the functioning of the enantiostyly was checked, a third floral morph was recognized (central). Considering the results obtained here, it is possible to conclude that the enantiostyly presents different functions in the two species, suggesting the possibility of deviations of the classical pattern of enantiostyly. / A enantiostilia é um polimorfismo que representa um exemplo de hercogamia recíproca, caracterizando-se por apresentar morfos florais que diferem reciprocamente em relação ao posicionamento dos elementos sexuais, resultando em flores que formam imagens especulares. Um morfo floral apresenta esses elementos voltados para o lado direito e no outro morfo esses elementos estão no lado esquerdo. Este mecanismo é interpretado como uma estratégia que maximiza a polinização cruzada. Muitas espécies do gênero Chamaecrista vêm sendo relatadas como enantiostílicas monomórficas, ou seja, apresentam os dois morfos florais em um mesmo indivíduo. Tendo em vista a alta representatividade do gênero em restingas, que são ambientes extremamente ameaçados, e a inexistência de estudos que investiguem mais profundamente a enantiostilia, este trabalho teve como objetivo investigar a biologia reprodutiva de duas espécies do gênero Chamaecrista em uma área de vegetação costeira em Pernambuco, Brasil enfocando os aspectos da enantiostilia. No primeiro capítulo a funcionalidade da enantiostilia em C. ramosa, foi verificada por meio de dados referentes à biologia floral, comportamento dos visitantes, sistema reprodutivo e aspectos da biologia reprodutiva. Esta espécie apresentou padrões de deposição e captação de pólen, típicos de espécies enantiostílicas descritas por outros estudos. Mostrou-se autocompatível, sendo visitada exclusivamente por abelhas. No segundo capítulo foi investigada a enantiostilia na espécie C. flexuosa, através de aspectos morfológicos, morfométricos e reprodutivos. A espécie apresentou morfologicamente, dois morfos florais (direito e esquerdo), quando se avaliou apenas a morfologia, e funcionalmente, três morfos (direito, esquerdo e central), através da análise morfométrica, o que pareceu favorecer a sua aptidão reprodutiva. Levando em consideração os resultados aqui encontrados é possível dizer que a enantiostilia nas espécies estudadas apresenta diferentes funcionalidades, o que mostra uma tendência de desvios nesse mecanismo, no entanto se desconhece para a enantiostilia quais as forças evolutivas que determinam tais variações.
70

A formação do poder da marca turística do país: experimentos sobre o efeito recíproco causado por destinos turísticos / Forming the power of countries\' tourism brands: experiments on the reciprocal effect caused by tourism destinations

Glauber Eduardo de Oliveira Santos 19 September 2016 (has links)
A atribuição de uma marca a um elemento não influencia o consumidor somente com relação ao elemento em si. Os efeitos dessa atribuição também podem recair sobre a própria marca, incidindo indiretamente sobre outros elementos que carregam esse símbolo de identificação. O efeito do produto que recebe a marca sobre o comportamento do consumidor em relação à própria marca tem sido chamado de \"efeito recíproco\". Até o presente, o efeito recíproco da atribuição de marcas foi estudado principalmente no contexto da extensão de marcas para novos bens e serviços. A presente pesquisa estuda o efeito recíproco em um contexto ainda não explorado, o das marcas turísticas de países. O objetivo da pesquisa é analisar de que forma o poder da marca turística do país é afetado pelos valores subjetivos dos destinos contidos em seu território. Para tanto, foi elaborado um modelo teórico baseado na perspectiva de marcas como símbolos de identificação que permitem a categorização de produtos por meio de esquemas mentais. Em termos empíricos, foram estudadas a valência e a linearidade da relação entre o valor subjetivo dos destinos e poder da marca turística do país. Foi examinada também a influência sobre o poder da marca turística do país exercida pela similaridade dos destinos do país. Além disso, foi analisado ainda o efeito moderador que o conhecimento do consumidor acerca das características turísticas do país exerce sobre o efeito recíproco dos valores subjetivos dos destinos. Os objetivos desta pesquisa são úteis para embasar uma série de decisões relativas à gestão de marcas, especialmente de marcas turísticas de países e regiões. Para alcançar os objetivos definidos, a presente pesquisa utilizou o método experimental. O primeiro experimento abordou o efeito dos valores subjetivos dos destinos sobre o poder da marca turística do país em um contexto formado por destinos e países hipotéticos, utilizando dados coletados a partir de uma amostra de 230 estudantes universitários brasileiros. O segundo experimento enfocou o caso do Brasil como destino de viagens turísticas a partir de uma amostra de 363 consumidores norte-americanos. Os resultados alcançados comprovaram a existência do efeito recíproco dos valores subjetivos dos destinos sobre o poder da marca turística do país. As evidências coletadas mostraram também que esse efeito não é linear, mas sim crescente em função dos valores subjetivos dos destinos. O efeito da similaridade dos destinos do país sobre o poder da marca turística deste não foi suportado pelos dados empíricos. Da mesma forma, o efeito moderador do conhecimento acerca das características turísticas do país incidente sobre o efeito recíproco dos valores subjetivos dos destinos também não foi evidenciado. / Assigning a brand to an element influences the consumer not only with respect to the element itself. The effects of this assignment may also fall on the consumer behavior regarding the brand, indirectly affecting other elements that display this symbol of identification. The effect of the product that receives the brand on consumer behavior towards the brand itself have been named reciprocal effects. To date, reciprocal effects were mainly studied in the context of brand extensions to new goods and services. The present research studies reciprocal effects in a context that has not been examined yet: the tourism brand of the country. The objective of this research is to analyze how the power of the tourism brand of the country is affected by the subjective values of destinations situated in its territory. To do that, a conceptual model was developed based on the perspective of brands as identification symbols that enable categorization of products through mental schemes. In empirical terms, the study focused on the valence and the linearity of this relationship. It also analyzed the effect of the similarity across country\'s destinations on the power of the national brand. A final analysis focused on the moderating role of consumer knowledge about tourism characteristics of the country falling upon the reciprocal effect of the subjective values of destinations. These objectives are useful to support a number of branding decisions, especially those regarding countries and regions\' tourism brands. Two experiments were conducted in order to achieve these objectives. The first experiment addressed the effects of subjective values of destinations on the power of the tourism brand of the country in a context of hypothetical destinations and countries. It used data collected from a sample of 230 Brazilian undergraduate students. The second experiment focused on the Brazilian case by using a sample of 363 US consumers. The results evidenced the existence of the reciprocal effect of subjective values of destinations on the power of the tourism brand of the country. The experiments also showed that this effect is not linear, but increasing with respect to the subjective values of destinations. The effect of the similarity across destinations on the power of the national tourism brands was not supported by empirical data. Similarly, the moderating effect of knowledge about tourism characteristics of the country on the reciprocal effect of subjective values of destinations was not evidenced.

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