• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 408
  • 124
  • 56
  • 39
  • 9
  • 8
  • 7
  • 6
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 812
  • 334
  • 142
  • 139
  • 81
  • 77
  • 69
  • 67
  • 65
  • 62
  • 60
  • 51
  • 50
  • 49
  • 46
  • 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.
561

A prática do canto coral infantil como processo de musicalização / A study on children education through the choir singing pratice

Oliveira, Cleodiceles Branco Nogueira de 20 August 2018 (has links)
Orientador: Carlos Fernando Fiorini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-20T19:49:37Z (GMT). No. of bitstreams: 1 Oliveira_CleodicelesBrancoNogueirade_M.pdf: 4799497 bytes, checksum: 6e4d95e2b0d97373282c260943c5fdcb (MD5) Previous issue date: 2012 / Resumo: Esta dissertação tem por finalidade apresentar uma proposta de musicalização infantil através de canto coral nas escolas e os benefícios que essa prática traz para a criança. Com base na pesquisa bibliográfica como referencial teórico e em parceria com o Instituto Cultural Canarinhos da Terra através de seu programa O Coral na Escola, foi realizado um trabalho onde cerca de 25 crianças de uma Escola Municipal de Ensino Básico, situada na região de Campinas tiveram a oportunidade de participar de aulas de Canto Coral ao longo do ano de 2010. Através da pesquisa de campo pode-se destacar a importância de ter uma equipe qualificada para a realização de um trabalho de coro infantil bem como os benefícios que tal prática traz para a formação da criança / Abstract: This dissertation aims to present a proposal for Music Education to children through Choral Singing in Schools, and discuss the benefits that this practice brings to the child. Based on a bibliographic research as a theoretical reference, and in partnership with Instituto Cultural Canarinhos da Terra through its program "O Coral na Escola", 25 children from the Escola Municipal de Ensino Basico, located in the region of Campinas, had the opportunity to participate in choral singing lessons throughout the year 2010. Through this research, it was possible to highlight not only the importance of having a qualified staff working with a children's choir, but also the benefits that this practice can bring to the child's education / Mestrado / Praticas Interpretativas / Mestre em Música
562

Soft-Template Construction of 3D Macroporous Polypyrrole Scaffolds

Liu, Shaohua, Wang, Faxing, Dong, Renhao, Zhang, Tao, Zhang, Jian, Zheng, Zhikun, Mai, Yiyong, Feng, Xinliang 07 May 2018 (has links) (PDF)
No description available.
563

Two-Dimensional Mesoscale-Ordered Conducting Polymers

Liu, Shaohua, Zhang, Jian, Dong, Renhao, Gordiichuk, Pavlo, Zhang, Tao, Zhuang, Xiaodong, Mai, Yiyong, Liu, Feng, Herrmann, Andreas, Feng, Xinliang 08 May 2018 (has links) (PDF)
Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assemblies in different dimensions to achieve 2D conducting polymer nanosheets with structural ordering at the mesoscale. The supramolecular assemblies of amphipathic perfluorinated carboxylic acids and block co-polymers serve as 2D interfaces and meso-inducing moieties, respectively, which guide the polymerization of aniline into 2D, freestanding mesoporous conducting polymer nanosheets. Grazingincidence small-angle X-ray scattering combined with various microscopy demonstrates that the resulting mesoscale-ordered nanosheets have hexagonal lattice with d-spacing of about 30 nm, customizable pore sizes of 7–18 nm and thicknesses of 13–45 nm, and high surface area. Such template-directed assembly produces polyaniline nanosheets with enhanced π–π stacking interactions, thereby resulting in anisotropic and record-high electrical conductivity of approximately 41 S cm–1 for the pristine polyaniline nanosheet based film and approximately 188 S cm–1 for the hydrochloric acid-doped counterpart. Our moldable approach creates a new family of mesoscale-ordered structures as well as opens avenues to the programmed assembly of multifunctional materials.
564

Élaboration d’un dispositif électroémissif flexible à base de réseaux interpénétrés de polymères / Elaboration of a flexible electroemissive device based on interpenetrating polymer networks

Goujon, Laurent 28 November 2011 (has links)
Ces travaux de thèse ont permis d'élaborer un dispositif électroémissif (DEE) fin (140 µm) et flexible à base de réseaux interpénétrés de polymères (RIP). Pour ce faire, un polymère conducteur électronique, le poly (3,4-éthylènedioxythiophène) (PEDOT), est interpénétré dans une matrice hôte de manière à obtenir un système dont l'architecture monobloc est comparable à celle d'un dispositif tri-couches. Une fois le système gonflé par un liquide ionique, le 1-éthyl-3-méthylimidazolium bis-trifluorométhylsulfonylimide (EMImTFSI), les propriétés optiques du DEE sont modulables entre 24 et 51 % de réflexion dans le moyen infrarouge (bande III) en faisant varier la tension électrique appliquée aux bornes du dispositif de -1,5V à +1,5V. Les propriétés thermomécaniques du DEE proviennent essentiellement de la matrice hôte. Cette dernière est un RIP combinant la souplesse, la flexibilité et la résistance à la traction du caoutchouc nitrile (NBR) aux propriétés de conductivité ionique du poly(oxyde d'éthylène) (POE) en présence de l'EMImTFSI. / During this thesis a thin (140 µm) and flexible electroemissive device (EED), based on interpenetrating polymer networks (IPN), was elaborated. An electronic conducting polymer, poly (3,4-ethylenedioxythiophene) (PEDOT), is interpenetrated in a host matrix to obtain a system whose monoblock architecture is comparable to a three-layers device. Once the system is swollen by an ionic liquid, 1-ethyl-3-methylimidazolium bis-trifluoromethyl sulfonylimide (EMImTFSI), the EED optical properties are tunable between 24 and 51% reflection in the mid-infrared (Band III) by varying the electrical voltage applied across the device from -1.5 V to +1.5 V. The EED thermomechanical properties are mainly from the host matrix. This is an IPN combining flexibility and tensile strength of nitrile butadiene rubber (NBR) with the ionic conductivity properties of poly (ethylene oxide) (PEO) in the presence of EMImTFSI.
565

Conducting polymer devices for biolectronics / Application des polymères conducteurs en bioélectronique

Khodagholy Araghy, Dion 27 September 2012 (has links)
Pas de résumé en français seulement en anglais / The emergence of organic electronics – a technology that relies on carbon-based semiconductors to deliver devices with unique properties – represents one of the most dramatic developments of the past two decades. A rapidly emerging new direction in the field involves the interface with biology. The “soft” nature of organics offers better mechanical compatibility with tissue than traditional electronic materials, while their natural compatibility with mechanically flexible substrates suits the non-planar form factors often required for implants. More importantly, their ability to conduct ions in addition to electrons and holes opens up a new communication channel with biology. The coupling of electronics with living tissue holds the key to a variety of important life-enhancing technologies. One example is bioelectronic implants that record neural signals and/or electrically stimulate neurons. These devices offer unique opportunities to understand and treat conditions such as hearing and vision loss, epilepsy, brain degenerative diseases, and spinal cord injury.The engineering aspect of the work includes the development of a photolithographic process to integrate the conducting polymer poly(3,4-ethylenedioxythiophene: poly(styrene sulfonate) (PEDOT:PSS) with parylene C supports to make an active device. The technology is used to fabricate electrocorticography (ECoG) probes, high-speed transistors and wearable biosensors. The experimental work explores the fundamentals of communication at the interface between conducting polymers and the brain. It is shown that conducting polymers outperform conventional metallic electrodes for brain signals recording.Organic electrochemical transistors (OECTs) represent a step beyond conducting polymer electrodes. They consist of a conducting polymer channel in contact with an electrolyte. When a gate electrode excites an ionic current in the electrolyte, ions enter the polymer film and change its conductivity. Since a small amount of ions can effectively “block” the transistor channel, these devices offer significant amplification in ion-to-electron transduction. Using the developed technology a high-speed and high-density OECTs array is presented. The dense architecture of the array improves the resolution of the recording from neural networks and the transistors temporal response are 100 μs, significantly faster than the action potential. The experimental transistor responses are fit and modeled in order to optimize the gain of the transistor. Using the model, an OECT with two orders of magnitude higher normalized transconductance per channel width is fabricated as compared to Silicon-based field effect transistors. Furthermore, the OECTs are integrated to a highly conformable ECoG probe. This is the first time that a transistor is used to record brain activities in vivo. It shows a far superior signal-to-noise-ratio (SNR) compare to electrodes. The high SNR of the OECT recordings enables the observation of activities from the surface of the brain that only a perpetrating probe can record. Finally, the application of OECTs for biosensing is explored. The bulk of the currently available biosensors often require complex liquid handling, and thus suffer from problems associated with leakage and contamination. The use of an organic electrochemical transistor for detection of lactate by integration of a room temperature ionic liquid in a gel-format, as a solid-state electrolyte is demonstrated.
566

Modification of Paper into Conductive Substrate for Electronic Functions : Deposition, Characterization and Demonstration

Montibon, Elson January 2011 (has links)
The thesis investigates the modification of paper into an ion- and electron-conductive material, and as a renewable material for electronic device. The study stretches from investigating the interaction between the cellulosic materials and the conducting polymer to demonstrating the performance of the conductive paper by printing the electronic structure on the surface of the conductive paper. Conducting materials such as conducting polymer, ionic liquids, and multi-wall carbon nanotubes were deposited into the fiber networks. In order to investigate the interaction between the conducting polymer and cellulosic material, the adsorption of the conducting polymer poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonate) (PEDOT:PSS) onto microcrystalline cellulose (MCC) was performed. Electroconductive papers were produced via dip coating and rod coating, and characterized. The Scanning Electron Microscopy (SEM) / Energy Dispersive Spectroscopy (EDS) images showed that the conducting polymer was deposited in the fiber and in fiber-fiber contact areas. The X-ray Photoelectron Spectroscopy (XPS) analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The effects of fiber beating and paper formation, addition of organic solvents and pigments (TiO2, MWCNT), and calendering were investigated. Ionic paper was produced by depositing an ionic liquid into the commercial base paper. The dependence to temperature and relative humidity of the ionic conductivity was also investigated. In order to reduce the roughness and improve its printability, the ionic paper was surface-sized using different coating rods.  The bulk resistance increased with increasing surface sizing. The electrochemical performance of the ionic paper was confirmed by printing PEDOT:PSS on the surface. There was change in color of the polymer when a voltage was applied. It was demonstrated that the ionic paper is a good ionic conductor that can be used as component for a more compact electronic device construction. Conductive paper has a great potential to be a flexible substrate on which an electronic structure can be constructed. The conduction process in the modified paper is due to the density of charge carriers (ions and electrons), and their short range mobility in the material. The charge carrying is believed to be heterogeneous, involving many charged species as the paper material is chemically heterogeneous. / <p>Fel ordningsnummer (2010:28) är angivet på omslaget av fulltextfilen.</p> / Printed Polymer Electronics on Paper
567

Développement et caractérisation de condensateurs nano-composites à base de tantale / Development and characterization of nano-composite capacitors based on tantalum

Malnoë, Thomas 03 March 2016 (has links)
Le développement des polymères conducteurs, surtout en termes de stabilité, a permis de les intégrer dans les dispositifs électroniques pour des applications à haute valeur ajoutée. C'est la raison pour laquelle les condensateurs tantale initialement basés sur la technologie MnO2, en tant que cathode, ont été améliorés avec le remplacement de cette dernière par un polymère organique conducteur. Ces nouveaux condensateurs tantale-polymère sont constitués d'une anode en tantale frittée, d'un film diélectrique en oxyde de tantale, et d'une cathode en polymère conducteur, typiquement le poly(3,4-éthylènedioxythiophène) (PEDOT). Le fonctionnement des condensateurs a d'abord été optimisé uniquement pour de faibles capacités par polymérisation in situ. L'étape suivante consiste à atteindre de plus grandes capacités par imprégnation du polymère conducteur pré-synthétisé. Notre travail a été axé sur la caractérisation fine et la fabrication de prototypes de condensateur. Pour mener à bien cette étude, chaque partie du condensateur tantale-polymère a été caractérisée par différentes techniques physico-chimiques. Nous avons, entre autres, étudié la microstructure du réseau de tantale et les propriétés de la solution commerciale de polymère conducteur pour déterminer les paramètres d'imprégnation des condensateurs. Les caractérisations effectuées au laboratoire sont complétées par une évaluation des performances électriques des prototypes fabriqués dans l'entreprise. Tout ce travail a contribué à la mise sur le marché d'une nouvelle gamme de condensateurs tantale-polymère par l'entreprise Exxelia Tantalum. En parallèle, une étude a été consacrée à la synthèse d'un nouveau couple de polymère plus performant dans le but de remplacer le polymère commercial. / The development of conducting polymers, especially in terms of environmental stability, has allowed them to be used in electronic devices for high value applications. That's why tantalum capacitors initially based on MnO2 cathode technology have been improved by the replacement of it with a conducting polymer. Tantalum-polymer capacitors consist of a sintered tantalum anode, an anodic tantalum oxide film as a dielectric, and a conductive polymer cathode made of poly (3,4-ethylenedioxythiophene) (PEDOT). Until recently, those capacitors have been optimized only for low capacities by in situ polymerization. The next step is to reach higher capacities using an impregnated conductive polymer. Our work focused on the characterization and fabrication of capacitors. The main study focused on the characterization of each part of the tantalum-polymer capacitor via physico-chemical investigations. We studied the microstructure of the tantalum network and the properties of the commercial polymer solution to determine parameters for the dip-coating of tantalum anodes. This laboratory characterization is complemented by an assessment of the electrical performances of samples within the company. All this work has contributed to a new range of tantalum-polymer capacitors by Exxelia Tantalum Company. At the same time, a study has been performed in the synthesis of a new pair of polymers in order to replace the commercial polymer.
568

Towards a curriculum for training undergraduate choral conducting students in South Africa

Van der Sandt, Johannes Theodorus 30 July 2013 (has links)
It is a feature of present-day schooling, in South Africa and abroad, that music teachers are expected to organise and direct vocal ensemble activities, for example, yet adequate preparation provided in higher education courses for this role that the school music teacher has to fulfil, seems lacking. The purpose of this study is to compile a knowledge base that will enable the planning and development of a choral conducting curriculum, for use in South African tertiary institutions. The curriculum should be aimed at aspirant teachers in primary and secondary schools and community leaders who are culturally aware and who have a responsibility and interest in the choral field. Choral conducting as a recognised subject of an undergraduate study package is a relatively new academic field in South Africa. The envisaged curriculum needs to enhance the proficiency of choral conducting students within an educational context. The thesis is presented in five chapters of which Chapter 1 represents the background to the study, Chapter 5 summarises the study with recommendations and a conclusion, whilst Chapters 2 – 4 constitute the greater part of the research. Chapter 2 – Towards a definition of an effective conductor, offers a perspective on the various roles of conductors and investigates the nature of the art of choral conducting in order to move towards a definition of an effective conductor. In Chapter 3 – Current choral conducting curricula, the present situation with regards to choral conducting curricula in Australia, Austria, Canada, Czech Republic, Estonia, Finland, Germany, Hungary, Norway, Philippines, Russia, Slovenia, South Africa, Sweden, the Netherlands, the United Kingdom and the United States of America is discussed. Chapter 4 – Choral conducting skills, examines the knowledge and skills that ought to be part of a choral conductor's proficiency. The meaning of each component and its characteristics are discussed. The primary method of research was the review of literature in order to acquire an in-depth understanding of the theme under investigation. The researcher also used the Internet as source of information on national and international choral conducting curricula. / Dissertation (DMus)--University of Pretoria / Music / unrestricted
569

Studies On Electronic Properties Of Amorphous Conducting Carbon Films

Bhattacharyya, Somnath 12 1900 (has links) (PDF)
No description available.
570

Membranes conductrices ioniques pour piles à combustible / Ion conducting membranes for fuel cells

Narducci, Riccardo 15 December 2014 (has links)
Dans cette thèse, les membranes perfluorosulfoniques (PFSA) et les polymères aromatiques sulfonés (SAP) sont étudiés en vue d'une meilleure compréhension de leurs propriétés thermodynamiques, d'hydratation, mècaniques et électriques.Concernant les PFSA: 1) Préparation de membranes Nafion ayant diverses morphologies et structures (amorphe, semi-cristalline, stratifiée) et relation avec les propriétés, comme la transition vitreuse, la fusion, la conductivité protonique. 2) Divers traitements de recuit ont été appliqués et analysés par une nouvelle méthode quantitative appelé INCA (Ionomère nc analyse), utilisant aussi des agents de recuit spéciaux. Concernant les SAP: 1) Synthèse in situ de polymères réticulés et clarification du mécanisme. 2) Optimisation du degré de reticulation en vue de la meilleure conductivité protonique. 3) Obtention d'ionomères conducteurs cationiques par échange de cations du SPEEK et détermination des propriétés de ces nouveaux ionomères. / In this thesis, perfluorosulfonic acid membranes (PFSA) and sulfonated aromatic polymers (SAP) are studied to better understandtheir thermodynamic, hydration, mechanical and electrical properties. The following main points were addressed:Regarding PFSA:1) Nafion membranes with various morphology and microstructure (amorphous, semi-crystalline, layered) were prepared and the relation to the properties, such as glass and melting transitions, and proton conductivity, was established.2) Various annealing treatments were performed and analyzed by the quantitative INCA (Ionomer nc Analysis) method using also special annealing agents. Regarding SAP:1) The in situ synthesis of cross-linked polymers was studied and the mechanism was clarified. 2) The degree of cross-linking was optimized for best proton conductivity.3) Cation-conducting ionomers were obtained by cation exchange of SPEEK and the properties of these new ionomers were determined.

Page generated in 0.0713 seconds