• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 280
  • 178
  • 60
  • 32
  • 31
  • 20
  • 17
  • 12
  • 10
  • 6
  • 5
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 789
  • 163
  • 141
  • 115
  • 108
  • 96
  • 80
  • 71
  • 68
  • 66
  • 63
  • 59
  • 58
  • 45
  • 45
  • 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.
511

Konsten att tämja en bild : Fotografiet och läsarens uppmärksamhet i 1800-talets Sverige / The Taming of an Image : Photography, Attention, and Reading in Nineteenth-Century Sweden

Bremmer, Magnus January 2015 (has links)
The present study inquires into the problematization of attention in the reception and distribution of photography in 19th-century Sweden. It investigates how photography’s alleged abundance of detail and indiscriminate reproduction became a problem in the reception of the medium. The problem became urgent when photographs were put to use by established discourses; specifically, when used in printed publications meant for a public. The thesis therefore argues that the problem of attention had a profound influence on how printed photographic or photographically illustrated editions (photo-texts) were modelled and arranged. For this purpose, the study affirms a particular focus on attention practices: the various ways in which the printed editions aim to regulate the reader’s attention before the supposedly distractive image. Specifically, the thesis focuses on how texts in these printed editions are arranged or juxtaposed in relation to the image, how they speak of and to the images, what values they reflect, and what effects they could be said to produce. Consequently, the present study is more than an investigation of a problem; it is also an inquiry into the various attempts to overcome this problem. The problem and its responsive practices will have different characteristics in the various contexts of individual discourses. Therefore, the study situates the problem of attention in four prominent genres of 19th-century photography: the topographical albums of photographic views, art books with photographic reproductions, the scientific atlas, and the photographically illustrated travelogue. These genres and forms of publication, as well as the discourses of attention relating to them, are discussed in separate chapters. Every chapter departs from a specific Swedish photographic edition from the nineteenth-century. In sum, the thesis aims – with its focus on the problematization of attention – at giving a new historical perspective on the emergent relation between photography and the printed word.
512

Electrically conductive textile coatings with PEDOT:PSS

Åkerfeldt, Maria January 2015 (has links)
In smart textiles, electrical conductivity is often required for several functions, especially contacting (electroding) and interconnecting. This thesis explores electrically conductive textile surfaces made by combining conventional textile coating methods with the intrinsically conductive polymer complex poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). PEDOT:PSS was used in textile coating formulations including polymer binder, ethylene glycol (EG) and rheology modifier. Shear viscometry was used to identify suitable viscosities of the formulations for each coating method. The coating methods were knife coating, pad coating and screen printing. The first part of the work studied the influence of composition of the coating formulation, the amount of coating and the film formation process on the surface resistivity and the surface appearance of knife-coated textiles. The electrical resistivity was largely affected by the amount of PEDOT:PSS in the coating and indicated percolation behaviour within the system. Addition of a high-boiling solvent, i.e. EG, decreased the surface resistivity with more than four orders of magnitude. Studies of tear strength and bending rigidity showed that textiles coated with formulations containing larger amounts of PEDOT:PSS and EG were softer, more ductile and stronger than those coated with formulations containing more binder. The coated textiles were found to be durable to abrasion and cyclic strain, as well as quite resilient to the harsh treatment of shear flexing. Washing increased the surface resistivity, but the samples remained conductive after five wash cycles. The second part of the work focused on using the coatings to transfer the voltage signal from piezoelectric textile fibres; the coatings were first applied using pad coating as the outer electrode on a woven sensor and then as screen-printed interconnections in a sensing glove based on stretchy, warp-knitted fabric. Sensor data from the glove was successfully used as input to a microcontroller running a robot gripper. These applications showed the viability of the concept and that the coatings could be made very flexible and integrated into the textile garment without substantial loss of the textile characteristics. The industrial feasibility of the approach was also verified through the variations of coating methods.
513

Liquid Exfoliation of Molybdenum Disulfide for Inkjet Printing

Forsberg, Viviane January 2016 (has links)
Since the discovery of graphene, substantial effort has been put toward the synthesis and production of 2D materials. Developing scalable methods for the production of high-quality exfoliated nanosheets has proved a significant challenge. To date, the most promising scalable method for achieving these materials is through the liquid-based exfoliation (LBE) of nanosheetsin solvents. Thin films of nanosheets in dispersion can be modified with additives to produce 2D inks for printed electronics using inkjet printing. This is the most promising method for the deposition of such materials onto any substrate on an industrial production level. Although well-developed metallic and organic printed electronic inks exist on the market, there is still a need to improve or develop new inks based on semiconductor materials such as transition metal dichalcogenides (TMDs) that are stable, have good jetting conditions and deliver good printing quality.The inertness and mechanical properties of layered materials such as molybdenum disulfide (MoS2) make them ideally suited for printed electronics and solution processing. In addition,the high electron mobility of the layered semiconductors, make them a candidate to become a high-performance semiconductor material in printed electronics. Together, these features make MoS2 a simple and robust material with good semiconducting properties that is also suitable for solution coating and printing. It is also environmentally safe.The method described in this thesis could be easily employed to exfoliate many types of 2D materials in liquids. It consists of two exfoliation steps, one based on mechanical exfoliation of the bulk powder utilizing sand paper, and the other inthe liquid dispersion, using probe sonication to liquid-exfoliate the nanosheets. The dispersions, which were prepared in surfactant solution, were decanted, and the supernatant was collected and used for printing tests performed with a Dimatix inkjetprinter. The printing test shows that it is possible to use the MoS2 dispersion as a printed electronics inkjet ink and that optimization for specific printer and substrate combinations should be performed. There should also be advances in ink development, which would improve the drop formation and break-off at the inkjet printing nozzles, the ink jetting and, consequently, the printing quality. / Sedan upptäckten av grafen har mycket arbete lagts på framställning och produktion av 2D-material. En viktig uppgift har varit att ta fram skalbara metoder för produktion av högkvalitativa  nanosheets via exfoliering. Den mest lovande skalbarametoden hittills har varit vätskebaserad exfoliering av nanosheets i lösningsmedel. Tunna filmer av nanosheets i dispersion kan anpassas med hjälp av tillsatser och användas för tillverkning av halvledare strukturer med inkjet-skrivare, vilket är den mest lovande metoden för på en industriell produktions nivå beläggaden typen av material på substrat. Även om det finns välutvecklade metalliska och organiskabläck för tryckt elektronik, så finns det fortfarande ett behov av att förbättra eller utveckla nya bläck baserade på halvledarmaterial som t.ex. TMD, som är stabila, har goda bestryknings  egenskaper och ger bra tryckkvalitet. Den inerta naturen tillsammans med de mekaniska egenskaperna som finns hosskiktade material, som t.ex. molybdendisulfid (MoS2), gör demlämpliga för flexibel elektronik och bearbetning i lösning. Dessutom gör den höga elektronmobiliteten i dessa 2D-halvledaredem till en stark kandidat som halvledarmaterial inom trycktelektronik. Det betyder att MoS2 är ett enkelt och robust material med goda halvledaregenskaper som är lämpligt för bestrykning från lösning och tryck, och är miljömässigt säker.Den metod som beskrivs här kan med fördel användas föratt exfoliera alla typer av 2D-material i lösning. Exfolieringensker i två steg; först mekanisk exfoliering av torr bulk med sandpapper, därefter används ultraljudsbehandling i lösning för att exfoliera nanosheets. De dispersioner som framställts i lösning med surfaktanter dekanterades och det övre skiktetanvändes i trycktester med en Dimatix inkjet-skrivare.Tryckprovet visar att det är möjligt att använda MoS2 -dispersion som ett inkjet-bläck och att optimering för särskildaskrivar- och substratkombinationer borde göras, såsom förbättringav bläcksammansättningen med avseende på droppbildning och break-off vid skrivarmunstycket, vilket i sin tur skulleförbättra tryckkvaliteten. / KM2 / Paper Solar Cells
514

Microstructuring inkjet-printed deposits from silver nanoparticules coalescence to the fabrication of interconnections for electronic devices. / Microstructuration des dépôts imprimés par jet d'encre de la coalescence des nanoparticules d'argent vers la réalisation d'interconnexions de composants électroniques.

Cauchois, Romain 07 February 2012 (has links)
Plusieurs défis subsistent pour la migration de l’électronique imprimée vers l’industrie, malgré des avancées récentes. Dans ces travaux de thèse, l’optimisation du procédé d’impression d’encres à base de nanoparticules d’argent (<Ø>=25 nm) en fonction de sa rhéologie et des interactions fluide/substrat a permis de réaliser des interconnexions électriques d’une épaisseur de 500 nm. Ces lignes imprimées sur des substrats silicium ou flexibles sont ensuite recuites par des méthodes conventionnelles (étuve ou infrarouge) ou sélectives (micro-onde) à des températures comprises entre 100 et 300°C.Une meilleure compréhension de la relation procédé/microstructure des couches minces imprimées, via plusieurs caractérisations cristallographiques (DRX, EBSD et EDX), a permis d’optimiser la croissance des domaines nanocristallins, activée pour des énergies de l’ordre de 3 à 5 kJ•mol-1. Outre les faibles contraintes résiduelles (70 MPa), cette optimisation permet d’atteindre de faibles résistivités électriques (3.4 µOhm•cm) associées à un accroissement de la cohérence des réseaux cristallins aux joints de grains. La probabilité de réflexion des électrons à ces interfaces peut être davantage réduite, grâce à une approche innovante de croissance orientée des cristallites par interdiffusion atomique à partir du substrat.La faible rigidité mécanique (E<50 GPa) de ces lignes initialement poreuses nécessite une étape de renforcement par texturation ou par croissance electroless pour résister aux étapes de micro-assemblage et de soudure filaire. La réalisation d’un démonstrateur fonctionnel a ainsi permis de valider la technologie d’impression pour la fabrication de composants électroniques. / Several challenges are still holding back the technological transfer of printed electronics to industry in spite of recent progresses. In this thesis work, the printing method of inks based on silver nanoparticles (<Ø>=25 nm) was optimized according to its rheology and to the fluid/substrate interactions for the fabrication of electrical interconnections with a thickness of 500 nm. These lines were printed on silicon or flexible substrates and annealed either by conventional (oven or infrared) or selective methods (microwave) at temperatures comprised between 100 and 300 °C.A better understanding of the relationship between process and microstructure of these printed thin films, based on several crystallographic equipments (XRD, EBSD and EDX), led to the optimization of nanocrystallites growth with an activation energy of about 3 to 5 kJ•mol-1. In addition to the low residual stress (70 MPa), this optimization is used to achieve low electrical resistivity (3.4 μOhm•cm) associated with a greater coherence of the crystal lattices at grain boundaries. The probability of electron scattering at such interfaces can be further reduced using an innovative approach of oriented crystallite growth by atomic interdiffusion from the substrate.The low mechanical stiffness (E<50 GPa) of these porous lines requires a reinforcement step either by crystalline texturation or by electroless growth to withstand the assembly and wire-bonding steps. The fabrication of a functional demonstrator thus validated the printing technology for the manufacture of electronic components.
515

Sebeprezentace českých sportovců na internetových sociálních sítích a její využití v masových médiích / Self-presentation of czech sportsmen on social networking sites and its usage in mass media

Novotný, Ondřej January 2014 (has links)
The diploma thesis "Self-presentation of Czech Sportsmen on Social Networking Sites and its Usage in Mass Media" deals with a new phenomenon of the few last years - social networking sites and their usage for the work of sports journalists in particular. The thesis sums up the essential information about history and beginnings of the most important social networking sites. It also outlines the impact on the work of journalists. The core of the thesis is an analysis of the process how the information from social networking sites make their way to the articles in media. This research is based on three major sporting events - the 2010 Winter Olympics in Vancouver, the 2012 Summer Olympics in London and the 2014 Winter Olympics in Sochi. It covers the production of two Czech daily newspaper - Mladá fronta DNES and daily Sport, the two printed media which provided the most comprehensive coverage of the Olympics. The thesis analyses the change of the news sources in the course of the last years, among which the social networking sites play a much bigger role than in the past. It focuses on determining the prevailing source for the articles during the Olympics. The thesis also explores whether the proportion of using the different sources changed during the years. It traces the amount of articles using...
516

Impression de silicium par procédé jet d’encre : des nanoparticules aux couches minces fonctionnelles pour applications photovoltaïques / Inkjet-printed silicon : from nanoparticles to functional thin-films for photovoltaic applications

Drahi, Etienne 21 March 2013 (has links)
Cette étude prend place dans le cadre du projet ANR Inxilicium visant à la réalisation de cellules solaires en couches minces de silicium par jet d’encre. Les nanoparticules de silicium sont des matériaux à fort potentiel pour la levée de verrous technologiques grâce à leurs propriétés spécifiques. Des encres de nanoparticules de Si issues de diverses méthodes de synthèse ont été imprimées par jet d’encre sur différents substrats : quartz, électrodes métalliques (aluminium, molybdène) et transparente conductrice (ZnO:Al). L’optimisation du procédé d’impression, de l’interaction encre/substrat (via la modulation de l’énergie de surface des substrats) et de l’étape de séchage a permis l’obtention de couches minces homogènes et continues (plusieurs centaines de nm à quelques µm d’épaisseur)A posteriori, une étape de recuit est nécessaire pour recouvrer des propriétés fonctionnelles. L’utilisation de nanoparticules à la physico-chimie de surface contrôlée fait décroître les températures de frittage de 1100 °C à environ 600 °C. En complément, des recuits sélectifs (micro-ondes et photonique) ont été évalués pour leur application sur des substrats flexibles et bas coûts.Les propriétés optiques et les interfaces électrode/silicium ont été examinées afin d’intégrer ces couches dans des dispositifs (cellule solaire…). La formation de transitions métallurgiques Al-Si et Mo-Si a été étudiées par DRX-in situ. L’ensemble de ces travaux a permis la réalisation d’une jonction PN montrant un comportement photovoltaïque à fort champ grâce aussi à la mise au point d’une méthode innovante de collage ouvrant la voie à une réduction du bilan thermique des procédés de fabrication. / This study takes place in the frame of the Inxilicium project from the National Research Agency, which targets the fabrication of silicon thin film solar cells by inkjet-printing. Thanks to their specific properties, silicon nanoparticles are materials with strong potential for technological breakthroughs. Silicon nanoparticle-based inks made by different synthesis routes have been inkjet-printed on different substrates: quartz, metallic electrodes (aluminum, molybdenum) and transparent electrodes (ZnO:Al). Homogeneous and continuous thin films (from several hundreds of nm to some µm thick) have been obtained through optimization of the printing process, the ink/substrate interaction (via substrates surface energy tuning) and the drying step.A posteriori, an annealing step is mandatory for recovering of functional properties. By using nanoparticles with tailored surface physical chemistry, the sintering temperature decreases from 1100 °C to 600 °C. In order to allow the use of this material on flexible and low cost substrates, selective sintering (microwave and photonics) have been also evaluated.Thin film optical properties and electrode/silicon interfaces have been investigated with the purpose to integrate those layers into devices (solar cells…). Metallurgical evolution of Al-Si and Mo-Si physical interfaces has been studied by in situ XRD.This work allowed the fabrication of a PN junction with a photovoltaic behaviour under strong polarization voltage thanks to the development of an innovative thermal pasting process, which opens the way to the reduction of process thermal budget.
517

Contribution à l'étude d'assemblages électroniques sur circuits imprimés à haute densité d'intégration comportant un nombre de couches important et des condensateurs enterrés

Puil, Jérôme 27 November 2008 (has links)
Cette thèse, qui s’intègre dans le cadre du projet européen EMCOMIT, a pour objectif de contribuer à l’étude des circuits imprimés haute densité d’intégration comportant un nombre de couches important et des composants enterrés. La qualification de cette technologie est effectuée en conduisant des simulations et des mesures électriques sur des véhicules de tests spécifiques. L’analyse des résultats électriques permet d’évaluer l’aptitude de ces matériaux à répondre aux exigences des applications de télécommunication et de technologie de l’information rapide. La fiabilité d’un assemblage de BGA de grande taille sur un circuit imprimé a été évaluée. Des simulations thermomécaniques ont été effectuées afin de calculer les contraintes résiduelles accumulées pendant le procédé d’assemblage puis l’énergie dépensée dans les parties critiques des joints au cours d’un cycle thermique. Simultanément, des BGA reportés sur des circuits imprimés ont été placés dans une chambre climatique et ont subi des variations de températures. / This thesis, which is part of the European EMCOMIT project, aims at contributing to the study of high density printed circuit board including a great number of internal layers and embedded components. The qualification of this technology is done by the way of simulations and electrical measurements on specific test vehicles. The electrical results allow estimating the performance of materials for telecommunication applications and speed data transfer. The reliability of the assembly of the large BGA on a printed circuit board has been evaluated. Thermomechanical simulations have been done in order to compute residual stresses stored during the assembly process and the deformation energy density in the solder joints during one thermal cycle. Simultaneously BGA soldered on printed circuits have been positioned in climatic chamber and have been subjected to temperature variations.
518

Modifikace detektoru z uhlíkové plsti měděnými mikročásticemi / Modification of carbon felt detector with copper microparticles

Baroch, Martin January 2019 (has links)
The first aim of this work was to develop copper modified carbon felt electrode for detection of amino acids, which are not electrochemically active on ordinary carbon electrodes. Phenylalanine solution at a concentration 1.0 mmol dm-3 was chosen as the testing solution. Electrode modified with electrochemical deposition of copper from mixture of copper(II) sulphate and sodium sulphate provided very low responses which were decreasing during first measurements, apparently because of insufficient amount of copper. Therefore, further experiments were performed using copper microparticles as a modifier. Copper microparticles activated in nitric acid at a concentration 80 mmol dm-3 were applied at carbon felt by several techniques and in different parts of the felt, i.e. by stirring the felt in microparticles suspension, by dripping of the suspension to the part of the felt in contact with capillary (proximal), between two parts of the carbon felt (sandwich) and at a part of the carbon felt in contact with electrolyte in a measuring cell (distal). Electrodes modified in the distal and in the sandwich arrangement were chosen as the best ones. In the last part, calibration dependences for phenylalanine in concentration range from 0.025 mmol dm-3 to 1.0 mmol dm-3 were measured on the last two electrodes....
519

[en] SIGNALS INTEGRITY IN HIGH SPEED PRINTED CIRCUIT BOARDS / [pt] INTEGRIDADE DE SINAIS EM PLACAS DE CIRCUITO IMPRESSO DE ALTAS TAXAS

VANESSA PRZYBYLSKI RIBEIRO MAGRI 14 February 2008 (has links)
[pt] Este trabalho tem como objetivo avaliar a viabilidade técnica para fabricação de placas de circuito impresso de múltiplas camadas com espessuras reduzidas mantendo a integridade dos sinais que se propagam em conexões inter- chip, nas taxas de transmissão de 1Gb/s e 10Gb/s para aplicações em redes de comunicações nos padrões 1GB Ethernet e 10GB Ethernet. A avaliação inclui o projeto de uma placa de 6 camadas de planos condutores, com espessura total de 1,29mm. A placa desenvolvida contém linhas de transmissão, vias e curvas, microcapacitores , microresistores e conectores I/O adequados para a faixa de freqüência em questão. / [en] The main purpose of this work is to evaluate the technical reliability to fabricate a Printed circuit board (PCB) with reduced thickness multilayer keeping signal Integrity on inter-chip connections in 1Gb/s and 10Gb/s (1GB Ethernet and 10GB Ethernet network communications). This evaluation includes the development of a PCB project with 06 layers and 1,29mm thickness. The PCB contains several transmission lines, vias, bends, microcapacitors, microresistors, connectors (I/O) suitable to this frequency band.
520

Det är utmanande och komplext att skriva enkelt och konkret : En studie om att anpassa en tryckt broschyr till en webbplats

Svalelid, Sara January 2019 (has links)
Den här studien undersöker hur en tryckt broschyr kan anpassas till en webbplats. Syftet med arbete är att se hur en informationsrik text kan skrivas i klarspråk och hur tydlighet och struktur påverkar webbanpassningen av en text. Jag har i denna studie utgått från en informationsbroschyr om värmepumpar utgiven av Energimyndigheten. På uppdrag av Energimyndigheten har jag omarbetat några sidor av broschyren och förberett dem för digitalt format. Målgruppen för informationsmaterialet är villaägare och energi- och klimatrådgivare som arbetar med rådgivning om värmepumpar. Jag har utgått från teorier gällande klarspråk, läsning på skärm, hierarkier, komposition och disposition. Jag har gjort en textanalys på den befintliga broschyren, genomfört en enkätundersökning med energi- och klimatrådgivare, intervjuat en värmepumpsexpert på Energimyndigheten och sedan genomfört utprovningar med villaägare. De slutsatser jag kommit fram till är att webbtexter behöver vara konkreta och korta. Användande av vardagliga uttryck och förklaringar av krångliga ord och facktermer, underlättar för läsaren. Ett bra exempel är att inkludera en ordlista. Det ska vara enkelt att få en snabb överblick av webbplatsens innehåll och användaren vill inte behöva skrolla ner på skärmen, det försämrar översikten och sammanhanget. Men den absolut viktigaste slutsatsen är att försöka förstå målgruppen och utgå från deras förkunskaper. / This study examines how a printed brochure can be adapted to a website. The aim of this study is to see how an information-rich text can be adapted to a digital format with focus on plain language and how structure can contribute to web adaptation of a text. In this study I have worked with an information brochure about heat pumps, the brochure is a publication from the Swedish Energy Agency. On behalf of the Swedish Energy Agency I have revised some pages of the brochure and prepared them for a digital format. The target group of this information brochure is Swedish homeowners and energy and climate advisors. The advisors help and guide homeowners who are looking for information about heat pumps. I have focused on theories of plain language, reading on screen, hierarchy, composition and disposition. A text analysis on the existing brochure has been performed and I have conducted a survey where I gathered opinions from the energy and climate advisors. I have also interviewed a heat pump expert at the Swedish Energy Agency and conducted usability test with homeowners. The conclusions of my study are that web texts need to be concise and short. The usage of ordinary words is important and to always explain difficult phrases and technical words is of great help to the reader. A good example is to include a dictionary. It should be easy to get a quick overview of the site content and the user should see the full page info, having to scroll down complicates the overview and context. But the most important conclusion is that the writer needs to understand the target group and their previous knowledge.

Page generated in 0.0853 seconds