• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 46
  • 19
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 89
  • 17
  • 17
  • 15
  • 15
  • 13
  • 13
  • 12
  • 12
  • 9
  • 8
  • 8
  • 8
  • 7
  • 7
  • 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.
81

Étude des propriétés de transport dans les hydrogels de curdlan

Gagnon, Marc-André 12 1900 (has links)
Les hydrogels de polysaccharide sont des biomatériaux utilisés comme matrices à libération contrôlée de médicaments et comme structures modèles pour l’étude de nombreux systèmes biologiques dont les biofilms bactériens et les mucus. Dans tous les cas, le transport de médicaments ou de nutriments à l’intérieur d’une matrice d’hydrogel joue un rôle de premier plan. Ainsi, l’étude des propriétés de transport dans les hydrogels s’avère un enjeu très important au niveau de plusieurs applications. Dans cet ouvrage, le curdlan, un polysaccharide neutre d’origine bactérienne et formé d’unités répétitives β-D-(1→3) glucose, est utilisé comme hydrogel modèle. Le curdlan a la propriété de former des thermogels de différentes conformations selon la température à laquelle une suspension aqueuse est incubée. La caractérisation in situ de la formation des hydrogels de curdlan thermoréversibles et thermo-irréversibles a tout d’abord été réalisée par spectroscopie infrarouge à transformée de Fourier (FT-IR) en mode réflexion totale atténuée à température variable. Les résultats ont permis d’optimiser les conditions de gélation, menant ainsi à la formation reproductible des hydrogels. Les caractérisations structurales des hydrogels hydratés, réalisées par imagerie FT-IR, par microscopie électronique à balayage en mode environnemental (eSEM) et par microscopie à force atomique (AFM), ont permis de visualiser les différentes morphologies susceptibles d’influencer la diffusion d’analytes dans les gels. Nos résultats montrent que les deux types d’hydrogels de curdlan ont des architectures distinctes à l’échelle microscopique. La combinaison de la spectroscopie de résonance magnétique nucléaire (RMN) à gradients pulsés et de l’imagerie RMN a permis d’étudier l’autodiffusion et la diffusion mutuelle sur un même système dans des conditions expérimentales similaires. Nous avons observé que la diffusion des molécules dans les gels est ralentie par rapport à celle mesurée en solution aqueuse. Les mesures d’autodiffusion, effectuées sur une série d’analytes de diverses tailles dans les deux types d’hydrogels de curdlan, montrent que le coefficient d’autodiffusion relatif décroit en fonction de la taille de l’analyte. De plus, nos résultats suggèrent que l’équivalence entre les coefficients d’autodiffusion et de diffusion mutuelle dans les hydrogels de curdlan thermo-irréversibles est principalement due au fait que l’environnement sondé par les analytes durant une expérience d’autodiffusion est représentatif de celui exploré durant une expérience de diffusion mutuelle. Dans de telles conditions, nos résultats montrent que la RMN à gradients pulsés peut s’avérer une approche très avantageuse afin de caractériser des systèmes à libération contrôlée de médicaments. D’autres expériences de diffusion mutuelle, menées sur une macromolécule de dextran, montrent un coefficient de diffusion mutuelle inférieur au coefficient d’autodiffusion sur un même gel de curdlan. L’écart mesuré entre les deux modes de transport est attribué au volume différent de l’environnement sondé durant les deux mesures. Les coefficients d’autodiffusion et de diffusion mutuelle similaires, mesurés dans les deux types de gels de curdlan pour les différents analytes étudiés, suggèrent une influence limitée de l’architecture microscopique de ces gels sur leurs propriétés de transport. Il est conclu que les interactions affectant la diffusion des analytes étudiés dans les hydrogels de curdlan se situent à l’échelle moléculaire. / Polysaccharide hydrogels are biomaterials used as controlled drug delivery matrices and serve as model scaffolds for the study of many biological systems like bacterial biofilms and mucus. In every case, the transport of drugs or nutriments across a hydrogel matrix is of prime importance. Therefore, the study of transport properties in hydrogels is an important issue for many fields of application. In this work, curdlan, a neutral bacterial polysaccharide made of β-D-(1→3) glucose repeating units, is used as a model hydrogel. Aqueous suspensions of curdlan can form thermogels of different conformations depending on the incubation temperature. In situ characterization of the preparation of thermo-reversible (low-set) and thermo-irreversible (high-set) curdlan hydrogels was first carried out using variable temperature attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR). The results allowed optimization of the gelling conditions leading to reproducible gel samples. Structural characterization of fully hydrated hydrogels, carried out by FT-IR imaging, environmental scanning electron microscopy (eSEM) and atomic force microscopy (AFM), allowed visualization of the different gel morphologies susceptible of influencing the diffusion of analytes in hydrogels. Our results show that both types of curdlan hydrogels have distinct microscopic architectures. The combination of pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy and NMR profiling allowed the study of self-diffusion and mutual diffusion on the same hydrogel system in similar experimental conditions. We showed that the diffusion of analytes in the gels is slower than in the aqueous solution. The diffusion experiments, carried out on a series of analytes of various sizes in both types of curdlan gels, show a decrease of the relative self-diffusion coefficient as a function of the analyte size. In addition, our results suggest that the equivalence between the self-diffusion and mutual-diffusion coefficients measured in the high-set curdlan gels is mainly due to the fact that the environment probed by the analytes during a self-diffusion experiment is representative of the one probed during a mutual-diffusion experiment. In such conditions, our results show that PFG NMR may present a valuable approach for the characterization of controlled drug release systems. Additional experiments show that the mutual-diffusion coefficient of dextran macromolecules is smaller than its self-diffusion coefficient in the same curdlan hydrogel. The difference between both transport rates is attributed to the different environment volumes probed by the analytes during the measurements. The similarities observed between the self-diffusion and mutual-diffusion coefficients, measured in both types of curdlan gels for all investigated analytes, suggest a limited influence of the microscopic gel architecture on its transport properties. It is therefore concluded that the interactions affecting the diffusion of the investigated analytes in the curdlan hydrogels lie at the molecular scale.
82

Étude des propriétés de transport dans les hydrogels de curdlan

Gagnon, Marc-André 12 1900 (has links)
Les hydrogels de polysaccharide sont des biomatériaux utilisés comme matrices à libération contrôlée de médicaments et comme structures modèles pour l’étude de nombreux systèmes biologiques dont les biofilms bactériens et les mucus. Dans tous les cas, le transport de médicaments ou de nutriments à l’intérieur d’une matrice d’hydrogel joue un rôle de premier plan. Ainsi, l’étude des propriétés de transport dans les hydrogels s’avère un enjeu très important au niveau de plusieurs applications. Dans cet ouvrage, le curdlan, un polysaccharide neutre d’origine bactérienne et formé d’unités répétitives β-D-(1→3) glucose, est utilisé comme hydrogel modèle. Le curdlan a la propriété de former des thermogels de différentes conformations selon la température à laquelle une suspension aqueuse est incubée. La caractérisation in situ de la formation des hydrogels de curdlan thermoréversibles et thermo-irréversibles a tout d’abord été réalisée par spectroscopie infrarouge à transformée de Fourier (FT-IR) en mode réflexion totale atténuée à température variable. Les résultats ont permis d’optimiser les conditions de gélation, menant ainsi à la formation reproductible des hydrogels. Les caractérisations structurales des hydrogels hydratés, réalisées par imagerie FT-IR, par microscopie électronique à balayage en mode environnemental (eSEM) et par microscopie à force atomique (AFM), ont permis de visualiser les différentes morphologies susceptibles d’influencer la diffusion d’analytes dans les gels. Nos résultats montrent que les deux types d’hydrogels de curdlan ont des architectures distinctes à l’échelle microscopique. La combinaison de la spectroscopie de résonance magnétique nucléaire (RMN) à gradients pulsés et de l’imagerie RMN a permis d’étudier l’autodiffusion et la diffusion mutuelle sur un même système dans des conditions expérimentales similaires. Nous avons observé que la diffusion des molécules dans les gels est ralentie par rapport à celle mesurée en solution aqueuse. Les mesures d’autodiffusion, effectuées sur une série d’analytes de diverses tailles dans les deux types d’hydrogels de curdlan, montrent que le coefficient d’autodiffusion relatif décroit en fonction de la taille de l’analyte. De plus, nos résultats suggèrent que l’équivalence entre les coefficients d’autodiffusion et de diffusion mutuelle dans les hydrogels de curdlan thermo-irréversibles est principalement due au fait que l’environnement sondé par les analytes durant une expérience d’autodiffusion est représentatif de celui exploré durant une expérience de diffusion mutuelle. Dans de telles conditions, nos résultats montrent que la RMN à gradients pulsés peut s’avérer une approche très avantageuse afin de caractériser des systèmes à libération contrôlée de médicaments. D’autres expériences de diffusion mutuelle, menées sur une macromolécule de dextran, montrent un coefficient de diffusion mutuelle inférieur au coefficient d’autodiffusion sur un même gel de curdlan. L’écart mesuré entre les deux modes de transport est attribué au volume différent de l’environnement sondé durant les deux mesures. Les coefficients d’autodiffusion et de diffusion mutuelle similaires, mesurés dans les deux types de gels de curdlan pour les différents analytes étudiés, suggèrent une influence limitée de l’architecture microscopique de ces gels sur leurs propriétés de transport. Il est conclu que les interactions affectant la diffusion des analytes étudiés dans les hydrogels de curdlan se situent à l’échelle moléculaire. / Polysaccharide hydrogels are biomaterials used as controlled drug delivery matrices and serve as model scaffolds for the study of many biological systems like bacterial biofilms and mucus. In every case, the transport of drugs or nutriments across a hydrogel matrix is of prime importance. Therefore, the study of transport properties in hydrogels is an important issue for many fields of application. In this work, curdlan, a neutral bacterial polysaccharide made of β-D-(1→3) glucose repeating units, is used as a model hydrogel. Aqueous suspensions of curdlan can form thermogels of different conformations depending on the incubation temperature. In situ characterization of the preparation of thermo-reversible (low-set) and thermo-irreversible (high-set) curdlan hydrogels was first carried out using variable temperature attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR). The results allowed optimization of the gelling conditions leading to reproducible gel samples. Structural characterization of fully hydrated hydrogels, carried out by FT-IR imaging, environmental scanning electron microscopy (eSEM) and atomic force microscopy (AFM), allowed visualization of the different gel morphologies susceptible of influencing the diffusion of analytes in hydrogels. Our results show that both types of curdlan hydrogels have distinct microscopic architectures. The combination of pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy and NMR profiling allowed the study of self-diffusion and mutual diffusion on the same hydrogel system in similar experimental conditions. We showed that the diffusion of analytes in the gels is slower than in the aqueous solution. The diffusion experiments, carried out on a series of analytes of various sizes in both types of curdlan gels, show a decrease of the relative self-diffusion coefficient as a function of the analyte size. In addition, our results suggest that the equivalence between the self-diffusion and mutual-diffusion coefficients measured in the high-set curdlan gels is mainly due to the fact that the environment probed by the analytes during a self-diffusion experiment is representative of the one probed during a mutual-diffusion experiment. In such conditions, our results show that PFG NMR may present a valuable approach for the characterization of controlled drug release systems. Additional experiments show that the mutual-diffusion coefficient of dextran macromolecules is smaller than its self-diffusion coefficient in the same curdlan hydrogel. The difference between both transport rates is attributed to the different environment volumes probed by the analytes during the measurements. The similarities observed between the self-diffusion and mutual-diffusion coefficients, measured in both types of curdlan gels for all investigated analytes, suggest a limited influence of the microscopic gel architecture on its transport properties. It is therefore concluded that the interactions affecting the diffusion of the investigated analytes in the curdlan hydrogels lie at the molecular scale.
83

以最大測驗訊息量決定通過分數之研究 / Study of the Standard Setting by the Maximum Test Information

謝進昌, Shieh, Jin-Chang Unknown Date (has links)
本研究目的,乃在運用試題反應理論中最大測驗訊息量的概念於精熟標準設定上作為探討的主軸,透過其歷史的演進與發展,衍生出詮釋本研究最大測驗訊息量法的三個面向,分別為:元素的搭配組合與調整、廣義測驗建構流程、多元效度等,並以此概念賦予解釋運用最大測驗訊息量於精熟標準設定時的合理性與適切性。同時,確立最大測驗訊息量法於公式意涵、試題選擇與統計考驗力面向的合理性,建立其於精熟標準上的理論基礎,而後,再輔以精熟/未精熟者分類一致性信度值以期提供多元效度證據。最後,探討測驗分數的轉換方法、差異能力描述,期能同時獲得量與質的測驗結果解釋。 綜整分析,可發現以下幾點結論: 一、運用最大測驗訊息量法於精熟標準設定時,在分類的信度指標上,顯示由此求得精熟標準,經交叉驗證後,大致可獲得滿意的結果,皆有高達九成以上的精確分類水準,且藉由區間的概念亦能充分顯現出,以最大測驗訊息量法求得之標準,可作為專家設定精熟標準時參考、判斷的優勢。而在分數轉換上,不論搭配換算古典測驗分數法或測驗特徵曲線構圖法時,其分類精熟/未精熟者的一致性表現,大致可獲得滿意的結果,乃是值得參照的組合策略。 二、在運用定錨點以解釋由最大測驗訊息量法於國中基本學力測驗求得之精熟標準時,可發現未精熟者乃僅需具備學科基礎知識與簡易圖示理解能力,而對於精熟者而言,則需進一步擁有對於廣泛學科知識的了解;複雜問題、資料與圖表詮釋;邏輯推理、分析實驗結果以獲得相關論點等能力,或者更高階之具備進階學科知識;綜合、評鑑資料、情境傳遞之訊息的能力。 三、探討測驗長度因素時,分析結果顯示不論採行最大測驗訊息量法、換算古典測驗分數法或是測驗特徵曲線構圖法,皆受此因素的影響,顯示測驗長度愈長,分類一致性愈高,此項結果乃與過去大多數的研究一致。另,由本資料分析結果乃建議測驗長度20題時,會是必備的基本題數要求值。此外,若從細部精確錯誤分類人數角度分析時,於實務用途上,可發現對於影響轉換分數時,產生差異分數的因素,決策者並不容易掌握與控制,但卻可藉由增加測驗長度,分散分數點的人數,以彌平錯誤分類的影響。 四、探討測驗異質性因素時,最大測驗訊息量法因具有因試題參數而調整估計受試者能力的特性,使得在異質測驗時,分類一致性仍能維持在不錯的水準之上。反觀換算古典測驗分數法與測驗特徵曲線構圖法,在固定精熟標準下,則有明顯的錯誤分類比率,此現象也反應出現行以固定60分作為及格(精熟)標準的缺失。 五、探討採用簡易測驗、困難測驗或常態測驗間於轉換分數上之效果時,由換算古典測驗分數法或測驗特徵曲線構圖法轉換來自最大測驗訊息量法之精熟標準時,資料分析結果顯示,不論於何種測驗難度類型中,採用何種轉換方式,並不會嚴重影響轉換分數間一致性分類的效果。另,若從細部精確錯誤分類人數角度分析時,本研究所採之最大測驗訊息量法,因具備隨測驗難易程度來決定門檻的特性,於簡易測驗中求得之精熟標準較低,而於困難測驗中求得之精熟標準相對較高,使得於轉換分數上,即使有較大的差異分數,亦不會造成嚴重的錯誤分類人數。 六、在探討測驗長度、測驗異質性因素與定錨點題目篩選間互動關係時,分析結果顯示,測驗長度與測驗異質性,並非是絕對影響定錨點題目篩選的因素,更重要的在於最大試題訊息量所對應之最適能力值是否能與定錨點相搭配。 綜整之,本研究所採最大測驗訊息量法,經檢驗後,於分類一致性上乃具有不錯的表現,且搭配相對強韌、嚴謹的理論支持與適切測驗結果解釋方法等,是最適合用於大型考試上使用。因此,乃建議未來政府單位或實務工作者於進行大型證照、資格檢定考試時,可考慮使用本策略。 / The purpose of this study is to adopt the concepts of IRT maximum test information to standard setting. At first, we are trying to discover three facets of interpretation in using the maximum test information to standard setting through the historical movement of standard setting. The three facets are component combination and adjustment, generalized test construction processes and multiple validities. Depending on these three concepts, we can easily explain the reasonableness and appropriateness of maximum test information approach. After that, we further investigate the reasonableness from the dimensions of definition of formula, item selections and statistical power to establish the basic theory of the maximum information approach in standard setting. In addition, we also examine the effects on exact classification of master/non-master in expectation to provide multiple evidences for validity. Finally, the method of classical test scores transformation and difference ability description are discussed to provide quantitative and qualitative test result interpretation simultaneously. In sum, some conclusions are proposed. 1.In applying the maximum test information approach to standard setting, the effect on exact classification of master/ non-master may come to a satisfying result. We may have at least 90% exact classification performance. At the same time, we also find that the mastery standard deriving from the maximum test information approach may have some advantages being a starting reference point for experts to adjust on the basis of the view of confidence interval. In the aspect of classical test scores transformation, no matter what approach you take, the transformed classical test scores approach or test characteristic curve mapping method, the consistency of exact classification of master/ non-master may hold. We may suggest the combination strategy is really worthy to take into consideration in standard setting. 2.In applying the anchor point to interpret Basic Competency Test result, we may find non-master only has basic academic knowledge and simple graph understanding ability, but for the master, he may need extensive academic knowledge; ability of complicated problems、data and graph interpretation; logic reasoning、analyzing experimental result to get related issues. Moreover, advanced academic knowledge; ability of synthesizing and evaluating information from data and surroundings are also included. 3.In the aspect of test length, the result of this research shows no matter what approach you take, maximum test information approach、transformed classical test scores approach or test characteristic curve mapping method, they are all influenced. It shows the longer test length, the higher consistency of exact classification of master/non-master. This result is consistent to most of the studies in the past. On the other hand, we suggest the 20 items is a fundamental value. Moreover, from the view of exact number of error classification, we can find that the real factor affecting the difference scores in transforming classical test score is unable to control in practical usage, but we can just disperse the numbers of people in each test score point to reduce the influence of error classification by increasing test length. 4.In the aspect of diverse test difficulty, because the maximum test information approach possesses the characteristic of examinees’ ability adjustment depending on item parameters, it is less influenced to maintain a acceptable level of consistent classification. In contrast with the maximum test information approach, the transformed classical test scores approach and test characteristic curve mapping method may have obvious high ratio of error classification under the fixed mastery standard. This also reflects the deficiency of current fixed 60 points passing scores. 5.In the aspect of analyzing the effect of score transformation between easy、hard and normal test, this research shows no matter what approach you take in any type of test difficulty, they may not severely influenced. Furthermore, from the view of exact number of error classification, because the maximum test information approach possesses the characteristic of deciding passing level depending on the degree of test difficulty (the lower mastery standard in easy test and the higher in hard test), it may not lead to a severe error classification even if there exists a large difference score in classical test score transformation. 6.In the aspect of interaction between test length、diverse test difficulty and anchor items selection, this research shows that test length and diverse test difficulty are not the real factors affecting anchor items selection. The more accurate cause is if the mastery standard deriving from the maximum test information approach may coordinate with the anchor point or not. In sum, the maximum test information approach may not only lead to a satisfying exact classification performance after analysis, but also be supported by strong and strict theory and accompany proper test result interpretation method. It is the most proper method in standard setting for large-sized test. Finally, we suggest the government or practitioners may consider adopting this strategy for future usage.
84

Multiliteracies : a critical ethnography : pedagogy, power, discourse and access to multiliteracies

Mills, Kathy Ann January 2006 (has links)
The multiliteracies pedagogy of the New London Group is a response to the emergence of new literacies and changing forms of meaning-making in contemporary contexts of increased cultural and linguistic diversity. This critical ethnographic research investigates the interactions between pedagogy, power, discourses, and differential access to multiliteracies, among a group of culturally and linguistically diverse learners in a mainstream Australian classroom. The study documents the way in which a teacher enacted the multiliteracies pedagogy through a series of mediabased lessons with her year six (aged 11-12 years) class. The reporting of this research is timely because the multiliteracies pedagogy has become a key feature of Australian educational policy initiatives and syllabus requirements. The methodology of this study was based on Carspecken's critical ethnography. This method includes five stages: Stage One involved eighteen days of observational data collection over the course of ten weeks in the classroom. The multiliteracies lessons aimed to enable learners to collaboratively design a claymation movie. Stage Two was the initial analysis of data, including verbatim transcribing, coding, and applying analytic tools to the data. Stage Three involved semi-structured, forty-five minute interviews with the principal, teacher, and four culturally and linguistically diverse students. In Stages Four and Five, the results of micro-level data analysis were compared with macro-level phenomena using structuration theory and extant literature about access to multiliteracies. The key finding was that students' access to multiliteracies differed among the culturally and linguistically diverse group. Existing degrees of access were reproduced, based on the learners' relation to the dominant culture. In the context of the media-based lessons in which students designed claymation movies, students from Anglo-Australian, middle-class backgrounds had greater access to transformed designing than those who were culturally marginalised. These experiences were mediated by pedagogy, power, and discourses in the classroom, which were in turn influenced by the agency of individuals. The individuals were both enabled and constrained by structures of power within the school and the wider educational and social systems. Recommendations arising from the study were provided for teachers, principals, policy makers and researchers who seek to monitor and facilitate the success of the multiliteracies pedagogy in culturally and linguistically diverse educational contexts.
85

Antenas planares multicamadas com materiais supercondutores e fot?nico para comunica??es m?veis

Alves, George Dennes Fernandes 04 August 2006 (has links)
Made available in DSpace on 2014-12-17T14:55:34Z (GMT). No. of bitstreams: 1 GeorgeDFA_Capa_ate_pag15.pdf: 8968407 bytes, checksum: 05f7b40d8df8312cf173aaad3ec43f83 (MD5) Previous issue date: 2006-08-04 / Recently, planar antennas have been studied due to their characteristics as well as the advantages that they offers when compared with another types of antennas. In the mobile communications area, the need for this kind of antennas have became each time bigger due to the intense increase of the mobile communications this sector. That needs of antennas which operate in multifrequency and wide bandwidth. The microstrip antennas presents narrow bandwidth due the loss in the dielectric generated by radiation. Another limitation is the radiation pattern degradation due the generation of surface waves in the substrate. In this work some used techniques to minimize the disadvantages (previously mentioned) of the use of microstrip antennas are presented, those are: substrates with PBG material - Photonic Bandgap, multilayer antennas and with stacked patches. The developed analysis in this work used the TTL - Transverse Transmission Line method in the domain of Fourier transform, that uses a component of propagation in the y direction (transverse to the direction real of propagation z), treating the general equations of electric and magnetic field as functions of Ey and Hy. One of the advantages of this method is the simplification of the field equations. therefore the amount of equations lesser must the fields in directions x and z be in function of components Ey and Hy. It will be presented an brief study of the main theories that explain the superconductivity phenomenon. The BCS theory. London Equations and Two Fluids model will be the theories that will give support the application of the superconductors in the microfita antennas. The inclusion of the superconductor patch is made using the resistive complex contour condition. This work has as objective the application of the TTL method to microstrip structures with single and multilayers of rectangular patches, to obtaining the resonance frequency and radiation pattern of each structure / Recentemente as antenas planares t?m despertado interesses devido ?s suas caracter?sticas, assim como pelas vantagens que oferecem quando comparadas com os demais tipos de antenas. Na ?rea de comunica??es m?veis a necessidade de antenas desse tipo tem-se tornado cada vez maior devido ao intenso crescimento desse setor, necessitando de antenas que operem em multifreq??ncia e em banda larga. As antenas de microfita apresentam largura de banda estreita devido ?s perdas no diel?trico geradas pela irradia??o. Outra limita??o ? a degrada??o do diagrama de irradia??o devido ? gera??o de ondas de superf?cie no substrato. Neste trabalho s?o apresentadas algumas t?cnicas usadas para tentar minimizar as desvantagens (citadas acima) do uso de antenas de microfita, sendo elas: substratos com material PBG - Photonic Bandgap, antenas em multicamadas e a utiliza??o de patches fabricados de materiais supercondutores. As an?lises desenvolvidas neste trabalho foram realizadas com a utiliza??o do m?todo LTT - Linha de Transmiss?o Transversa no dom?nio da transformada de Fourier, que utiliza uma componente de propaga??o na dire??o y (transversa ? dire??o real de propaga??o z), tratando assim as equa??es gerais dos campos el?tricos e magn?ticos em fun??es de Ey e Hy. Uma das vantagens desse m?todo ? a simplifica??o das equa??es de campo, pois a quantidade de equa??es ? menor devido os campos nas dire??es x e z ficarem em fun??o das componentes Ey e Hy. Ser? apresentado um breve estudo das principais teorias que explicam o fen?meno da supercondutividade. As teorias BCS, Equa??es de London e modelo dos Dois Fluidos ser?o as teorias que dar?o suporte a aplica??o dos supercondutores nas antenas microfita. A inclus?o do patch supercondutor ? feita utilizando-se a condi??o de contorno complexa resistiva. Este trabalho tem como objetivo a aplica??o do m?todo LTT ?s estruturas de microfita
86

Transformerat stadsrum : öppnar upp och länkar samman / Transformed Urban Space : Opens and connects Husby areas

Skalmstad, Peter January 2013 (has links)
Mitt syfte med projektet är att vitalisera stadsdelen Husby i nordvästra Stockholm. Bryta upp zonerade områden och addera fler och varierade funktioner som definierar nya stråk, länka samman omtyckta områden och överbrygga platser som upplevs otrygga. Sammantaget ger det förutsättningar för ett mer levande stadsliv som attraherar fler att vilja bo, bo kvar och göra bostadskarriär i Husby. Centrala begrepp i projektet är mångfald, trygghet, flexibilitet och hållbarhet. Jag har arbetat med att identifiera, bevara och utveckla kvaliteter i kombination med att öppna upp befintlig bebyggelse som präglas av upprepning, slutenhet och rationella byggmetoder samt addera ny bebyggelse för att få en större mångfald och ett mer flexibelt utbud av både lokaler, bokaler och bostäder men även genom att analysera och bearbeta områdets struktur. Fokus har legat på de trafikseparerade miljöerna och hur de kan vidareutvecklas genom att bland annat addera gångvägar och skapa nya stråk längst tillfartsgatorna och samtidigt bevara kvaliteter som de nivåseparerade korsningarna mellan gångvägarna och bilvägarna erbjuder med säker skolväg och en trygg bilfri miljö för barnen. / My purpose of this project is to revitalize the District of Husby in northwestern Stockholm. Diversify zoned areas by adding and varying functions that define new pathways, link popular areas and overcome sites experienced as insecure. Overall, it may provide the conditions for a more vibrant city life attracting more people to stay on and climb the property ladder in Husby. The key concepts of the project is diversity, security, flexibility and sustainability. I have been working on preserving and developing qualities of the area in order to change existing buildings characterised by repetition, closed facades, rational building design and construction methods to obtain a greater diversity and a more flexible range of both business premises, housing and live-in commercial properties and also by analysing and transforming the city structure. Focus has been on the traffic separation environment and how it could be further developed by adding walkways along the access roads while still preserving qualities such as a car free environment for the children living in the area.
87

Effet de la stérilisation par électrons accélérés sur les COC et sur l'impact des interactions avec des molécules actives / Effect of electron beam radio-sterilization on cyclo olefin copolymers and its impact on the interactions with active molecules

Barakat, Hala 24 January 2013 (has links)
L’objectif de ce travail de thèse était d’étudier l’effet de la stérilisation par électrons accélérés sur les copolymères d’oléfines cycliques (COC), utilisés comme conditionnement de produits pharmaceutiques, ainsi que son impact sur les interactions avec des formulations pharmaceutiques. Grâce à la méthodologie analytique adoptée qui a fait appel à différentes techniques de caractérisation, telles que la chromatographie d’exclusion stérique, la chromatographie liquide haute performance à polarité de phases inversée, la spectroscopie infra rouge à transformée de Fourier, la microscopie à force atomique et les mesures d’angles de contact, nous avons pu mettre en évidence différents types de modifications dans le volume et sur la surface du matériau après stérilisation ainsi qu’après vieillissement. La modification principale du dans la masse du matériau, observée à la dose réglementaire de stérilisation (25 kGy), est la scission des chaînes du polymère, qui s’accompagne de la création de composés de faible masse molaire, donc de migrants potentiels risquant d’influencer la sécurité d’emploi des COC. En effet, certains de ces composés ont été retrouvés avec une concentration relativement importante dans les solutions de mise en contact avec les COC stérilisés, et notamment en solution aqueuse. Toutefois, l’étude préliminaire de toxicité a montré l’absence de cytotoxicité des extractibles obtenus à la dose de la stérilisation.Les modifications relatives à la surface des COC radio-stérilisés sont, quant à elles, de deux natures : physique avec une augmentation de la rugosité de surface et chimique avec la formation de produits d’oxydation polaires ; ces deux types de modifications conduisent à l’augmentation de la mouillabilité de surface. Cependant dans certains cas, notamment après vieillissement, ces modifications sont relativement faibles, même à des doses supérieures à celle préconisée pour la stérilisation, ce qui peut être corrélé à l’absence de l’effet de l’irradiation sur le comportement des COC vis-à-vis des solutions médicamenteuses. En effet, aucune variation de la sorption des principes actifs choisis n’a été montrée entre les COC irradiés et non irradiés vieillis. / The aim of this work was to study the effect of electron beam radio-sterilization on cyclo olefins copolymers (COC) used as pharmaceutical storage materials, as well as to investigate its impact on the interaction with pharmaceuticals formulations. Due to the analytical methodology used which dealt with different techniques of characterization such as size exclusion chromatography, reversed phase high performance liquid chromatography, Fourier transformed infrared spectroscopy, atomic force microscopy and contact angle measurements, we have been able to put into evidence different kinds of modifications both in the bulk and on the surface of the sterilized material and also after ageing.The principal modification of material’s bulk, observed at the recommended dose for sterilization (25 kGy), was polymer chains scissions, accompanied with creation of low molecular weight compounds, that are potentials migrants that risk to affect the safe use of COC. Indeed, some of these compounds have been found with a relatively important concentration in the solutions where sterilized COC was stored, especially in aqueous solutions. However, the preliminary study of toxicity has shown the absence of cytotoxicity of the extractables obtained at the sterilization dose.Surface modifications of radio-sterilized COC are of two types: a physical one, with an increase of the surface’s roughness and a chemical one with the formation of polar oxidation products; these two modifications result in an increase of surface’s wettability that may be important. However, in some cases such as for aged samples, these modifications are relatively weak even at doses higher than the one recommended for sterilization, which can explain the absence of the effect of radiation on the behavior of COC towards drug solutions. Indeed, no variation of drug sorption has been observed between aged COC irradiated and none irradiated.
88

Microstructure, texture and mechanical property evolution during additive manufacturing of Ti6Al4V alloy for aerospace applications

Antonysamy, Alphons Anandaraj January 2012 (has links)
Additive Manufacturing (AM) is an innovative manufacturing process which offers near-net shape fabrication of complex components, directly from CAD models, without dies or substantial machining, resulting in a reduction in lead-time, waste, and cost. For example, the buy-to-fly ratio for a titanium component machined from forged billet is typically 10-20:1 compared to 5-7:1 when manufactured by AM. However, the production rates for most AM processes are relatively slow and AM is consequently largely of interest to the aerospace, automotive and biomedical industries. In addition, the solidification conditions in AM with the Ti alloy commonly lead to undesirable coarse columnar primary β grain structures in components. The present research is focused on developing a fundamental understanding of the influence of the processing conditions on microstructure and texture evolution and their resulting effect on the mechanical properties during additive manufacturing with a Ti6Al4V alloy, using three different techniques, namely; 1) Selective laser melting (SLM) process, 2) Electron beam selective melting (EBSM) process and, 3) Wire arc additive manufacturing (WAAM) process. The most important finding in this work was that all the AM processes produced columnar β-grain structures which grow by epitaxial re-growth up through each melted layer. By thermal modelling using TS4D (Thermal Simulation in 4 Dimensions), it has been shown that the melt pool size increased and the cooling rate decreased from SLM to EBSM and to the WAAM process. The prior β grain size also increased with melt pool size from a finer size in the SLM to a moderate size in EBSM and to huge grains in WAAM that can be seen by eye. However, despite the large difference in power density between the processes, they all had similar G/R (thermal gradient/growth rate) ratios, which were predicted to lie in the columnar growth region in the solidification diagram. The EBSM process showed a pronounced local heterogeneity in the microstructure in local transition areas, when there was a change in geometry; for e.g. change in wall thickness, thin to thick capping section, cross-over’s, V-transitions, etc. By reconstruction of the high temperature β microstructure, it has been shown that all the AM platforms showed primary columnar β grains with a <001>β.
89

Městské lázně / The Municipal Baths

Adamsonová, Kristína January 2010 (has links)
ARCHITECTURE The centre and entrance point for atrection a relx is terace with pool, with corridor to cafe and skylights that leads to reception. Around this atrium, there is a ramp, rising up. Pools are not see n ko the screens are individual attractions, atmosphere. The height change of each pool, sauna and whether this involves physical effort is rewarded with open views to the surroundings and relax themselves. Entering the building through a covered, but bright bay, passage is a continuation of the street fishing. Thus the very end of the reception side. Thus eliminate the problem of a parcel which is like a scene out of town. Layout In the passages suggest leaving the car park, Kafe-bar with a simple menu and fresh multifunctional workshop, creative playground. It is known fact, that in the old spa locations to find valuable pieces of pottery, small painting and sculpture and other artifacts that speak of links with the vivacious work, relax, relax with a manual and spiritual. This room will also serve as a nursery for parents resting in the spa, in the specified date and time. Upon entering the spa itself, the reception with high ceilings and skylights from the terrace, the visitor to the issue of changing rooms with bathroom facilities. Consequently, the choice whether to receive the attractions, or go down to the fitness center or gym. Another option is to move the spa itself. In the direction from the top down it is pliable dough, the blood will get the opposite route, in which the visitor shall issue a physical effort. 2np In addition to coffee for guests only and exit to the terrace, and massage booths are located. Much of the area occupied by the technical room, spa bath as well as administration. On the next floor guest vystkytne a larger foyer, drinking KURO room and swimming and first aid. Glass facades can be glanced only in forests of the Riviera, but the atrium, with an outdoor terrace and heated swimming pool at all times. Foyer is the actual beginning of the journey. The first ramp is rising just from my father. All the dark hallway, followed by a bright and translucent glass facades. The key is just a wall bordering the ramps and a few additional columns for the perimeter of the building. About half a meter above (and always rises only about 500 mm, the gradient of 1:16 to 8 meters length), the visitor gets to the first pool. Sunny southern facade is designed as a double, at this point is the greenhouse, it is no wonder that the first two pools are linked to breathing, inhalation, nature herbs. The hall (+7400) is glass mat glass sanitary unit consisting of two toilets, toilets for disabled people and installation bay. On one front wall of the shower. This element is repeated, the cabin is only 2.6 meters high (sv room is 3.65 meters), it was acting to hinder lightweight and transparent. On the left side counterclockwise overcomes next ramp stages. Pools are right to counter a výrivý. In this part of the facade facing the street catchment area, the intersection of fishing and of 8 m of pools have already seen the two interface Brno: Petrov and Špilberk. There is also a visitor gets to escape-connecting staircase. Possibility of shortening the path to the sauna is right here. The following pool of options in turn draws the double facade. Studenúuvodu make cold, shielded, north-facing environment. Hot pool at a height level of hygiene cab ...

Page generated in 0.0724 seconds