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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.
1

Buried screen-printed contacts for silicon solar cells

Jamshidi Gohari, Ebrahim January 2012 (has links)
A Simple way to improve solar cell efficiency is to enhance the absorption of light and reduce the shading losses. One of the main objectives for the photovoltaic roadmap is the reduction of metalized area on the front side of solar cell by fin lines. Industrial solar cell production uses screen-printing of metal pastes with a limit in line width of 70-80 μm. This paper will show a combination of the technique of laser grooved buried contact (LGBC) and Screen-printing is able to improve in fine lines and higher aspect ratio. Laser grooving is a technique to bury the contact into the surface of silicon wafer. Metallization is normally done with electroless or electrolytic plating method, which a high cost. To decrease the relative cost, more complex manufacturing process was needed, therefore in this project the standard process of buried contact solar cells has been optimized in order to gain a laser grooved buried contact solar cell concept with less processing steps. The laser scribing process is set at the first step on raw mono-crystalline silicon wafer. And then the texturing etch; phosphorus diffusion and SiNx passivation process was needed once. While simultaneously optimizing the laser scribing process did to get better results on screen-printing process with fewer difficulties to fill the laser groove. This project has been done to make the whole production of buried contact solar cell with fewer steps and could present a cost effective opportunity to solar cell industries. / <p>In collaboration with Institute for Photovoltaics <strong><em>IPV</em></strong>, University of Stuttgart.</p>
2

A non-contact laser ablation cell for mass spectrometry

Asogan, Dhinesh January 2011 (has links)
A common analytical problem in applying LA sampling concerns dealing with large planar samples, e.g. gel plates, Si wafers, tissue sections or geological samples. As the current state of the art stands, there are two solutions to this problem: either sub-sample the substrate or build a custom cell. Both have their inherent drawbacks. With sub-sampling, the main issue is to ensure that a representative is sample taken to correctly determine the analytes of interest. Constructing custom cells can be time consuming, even for research groups that are experienced or skilled, as they have to be validated before data can be published. There are various published designs and ideas that attempt to deal with the issue of large samples, all of which ultimately enclose the sample in a box. The work presented in this thesis shows a viable alternative to enclosed sampling chambers. The non-contact cell is an open cell that uses novel gas dynamics to remove the necessity for an enclosed box and, therefore, enables samples of any arbitrary size to be sampled. The upper size limit of a sample is set by the travel of the XY stages on the laser ablation system, not the dimensions of the ablation cell.
3

Design and Analysis of End-Effector Systems for Scribing on Silicon

Cannon, Bennion Rhead 06 August 2003 (has links) (PDF)
This thesis investigates end-effector systems used in a chemomechanical scribing process. Chemomechanical scribing is a method of patterning silicon to selectively deposit a monolayer of material on the surface of the silicon. This thesis details the development of a unique end-effector for chemomechanical scribing using a compliant mechanism solution. The end-effector is developed to scribe lines that have uniform geometry and produce less chipping on the surface of the silicon. The resulting scribing mechanism is passively controlled, has high lateral stiffness, and low axial stiffness. The mechanism is analyzed using the pseudo-rigid-body model and linear-elastic beam method to determine the axial stiffness, finite element methods to determine the lateral stiffness, and fatigue analysis to determine mechanism cycle life. This thesis also investigates the significance of mechanical factors on the chemomechanical scribing process using the compliant end-effector. The factors examined are scribing force, scribing speed, tip geometry, wafer orientation, and wetting liquid. The factors are analyzed using a two-step approach: first, an analysis of the influence of the mechanical factors on line characteristics and second, an analysis of the influence of line characteristics on line performance.
4

Plonasluoksnių saulės elementų apdirbimas ultratrumpais lazerių impulsais / Ultrashort pulsed laser processing of thin-films for solar cells

Gečys, Paulius 01 October 2012 (has links)
Disertacijos darbo tikslas buvo, modeliuojant bei vykdant eksperimentus, suprasti plonų sluoksnių, naudojamų Saulės elementuose, abliacijos procesus ultratrumpais impulsais, siekiant juos pritaikyti integruotų jungčių fotovoltiniuose moduliuose formavimui. Eksperimento rezultatams pagrysti buvo vykdomas lazerio spinduliuotės sklidimo bei pasiskirstymo plonasluoksnėje Saulės elemento struktūroje modeliavimas. Sugerta lazerio energija lokaliai užkaitiną medžiagą. Kadangi lazerinio proceso selektyvumas priklauso nuo medžiagos optinių savybių, todėl yra itin svarbu parinkti tinkamą lazerio spinduliuotės bangos ilgį, norint sukaupti spinduliuotę reikiamame plonasluoksnės struktūros sluoksnyje. Nustatyta, kad fundamentinė pikosekundinio lazerio spinduliuotė (1064 nm) yra optimaliausia P3 tipo rėžio formavimui CIGS Saulės elemente. Pramonės taikymams tai yra itin svarbu, nes tokiu atveju mažėja industrinės lazerinės sistemos sudėtingumas bei kaina. Saulės elementų efektyvumo tyrimai parodė nežymų fotoelektrinio efektyvumo sumažėjimą po lazerinio apdirbimo ultra trumpais impulsais, tačiau nebuvo užfiksuota defektų generacijos lazeriais paveiktose kanalo kraštų zonose. Disertacijoje pasiūlyti ir išbandyti pluošto formavimo ir lygiagretaus sluoksnių raižymo metodai, didinantys proceso našumą ir raižymo kokybę. Pikosekundiniai, didelio impulsų pasikartojimo dažnio lazeriai gali būti panaudoti didelės spartos bei aukštos kokybės Saulės elementų raižymo procesuose. / Present PhD thesis is the experimental and theoretical analysis of thin layer ultrashort pulsed laser ablation processes for photovoltaic devices. Experimental work was supported by modeling and simulation of energy coupling and dissipation inside the layers. The absorbed laser energy was transformed to localized transient heating inside the structure. Selectiveness of the ablation process was defined by optical and mechanical properties of the materials, and selection of the laser wavelength facilitated control of the structuring process. The 1064 nm wavelength was found optimal for the CIGS solar cell scribing in terms of quality and process speed. It is very positive result for industrial applications as the cost and the system complexity are decreased. The solar cell efficiency test revealed minor degradation in photo-electrical efficiency after the laser scribing was applied to the solar cell samples. Lock-in thermography measurements did not revealed any internal shunt formation during laser scribing with picosecond pulse duration. Picosecond lasers with fundamental harmonics and high repetition rates can be used to accomplish efficient and fast scribing process which is able to fit the demands for industrial solar cell scribing applications.
5

Ultrashort pulsed laser processing of thin-films for solar cells / Plonasluoksnių saulės elementų apdirbimas ultratrumpais lazerių impulsais

Gečys, Paulius 01 October 2012 (has links)
Present PhD thesis is the experimental and theoretical analysis of thin layer ultrashort pulsed laser ablation processes for photovoltaic devices. Experimental work was supported by modeling and simulation of energy coupling and dissipation inside the layers. The absorbed laser energy was transformed to localized transient heating inside the structure. Selectiveness of the ablation process was defined by optical and mechanical properties of the materials, and selection of the laser wavelength facilitated control of the structuring process. The 1064 nm wavelength was found optimal for the CIGS solar cell scribing in terms of quality and process speed. It is very positive result for industrial applications as the cost and the system complexity are decreased. The solar cell efficiency test revealed minor degradation in photo-electrical efficiency after the laser scribing was applied to the solar cell samples. Lock-in thermography measurements did not revealed any internal shunt formation during laser scribing with picosecond pulse duration. Picosecond lasers with fundamental harmonics and high repetition rates can be used to accomplish efficient and fast scribing process which is able to fit the demands for industrial solar cell scribing applications. / Disertacijos darbo tikslas buvo, modeliuojant bei vykdant eksperimentus, suprasti plonų sluoksnių, naudojamų Saulės elementuose, abliacijos procesus ultratrumpais impulsais, siekiant juos pritaikyti integruotų jungčių fotovoltiniuose moduliuose formavimui. Eksperimento rezultatams pagrysti buvo vykdomas lazerio spinduliuotės sklidimo bei pasiskirstymo plonasluoksnėje Saulės elemento struktūroje modeliavimas. Sugerta lazerio energija lokaliai užkaitiną medžiagą. Kadangi lazerinio proceso selektyvumas priklauso nuo medžiagos optinių savybių, todėl yra itin svarbu parinkti tinkamą lazerio spinduliuotės bangos ilgį, norint sukaupti spinduliuotę reikiamame plonasluoksnės struktūros sluoksnyje. Nustatyta, kad fundamentinė pikosekundinio lazerio spinduliuotė (1064 nm) yra optimaliausia P3 tipo rėžio formavimui CIGS Saulės elemente. Pramonės taikymams tai yra itin svarbu, nes tokiu atveju mažėja industrinės lazerinės sistemos sudėtingumas bei kaina. Saulės elementų efektyvumo tyrimai parodė nežymų fotoelektrinio efektyvumo sumažėjimą po lazerinio apdirbimo ultra trumpais impulsais, tačiau nebuvo užfiksuota defektų generacijos lazeriais paveiktose kanalo kraštų zonose. Disertacijoje pasiūlyti ir išbandyti pluošto formavimo ir lygiagretaus sluoksnių raižymo metodai, didinantys proceso našumą ir raižymo kokybę. Pikosekundiniai, didelio impulsų pasikartojimo dažnio lazeriai gali būti panaudoti didelės spartos bei aukštos kokybės Saulės elementų raižymo procesuose.
6

Разработка системы информационной поддержки проектирования робототехнических устройств и создание структуры проекта робота-манипулятора в среде PDM Teamcenter с возможностью дистанционного доступа к проекту : магистерская диссертация / Experimental and computer aided investigation of cutting process of brittle materials

Ваганов, К. А., Vaganov, K. A. January 2016 (has links)
This master thesis work was aimed to enhance the designing of robots using cloud technologies. Analytical review of software to design robots, including PDM systems, was made. The specific features of such systems are presented and necessary modules are selected for designing the robot manipulator using CAD and PDM tools. 3D model of industrial robot was created using Semens NX CAD software. All the standards and regulatory documents related to the robotics design were considered. The design sequence of the robot manipulator with reference to standards (GOST 2.103-68 and GOST 19.102-77) is described. The project structure was created with use of Siemens Teamcenter PDM software and cloud technologies. / Данная магистерская диссертация направлена на внедрение технологий проектирования робототехнических систем в облаке. Спроектирован робот манипуляционного типа, создана электронная структура проекта в облаке с использованием программы PDM, проект размещен и организован для дальнейшего развития в облаке.
7

... et les doigts d'écrire se referment sur la paume : recherche-création sur l'épaisseur de l'écriture

Mellet, Margot 11 1900 (has links)
Thèse en recherche-création. En parallèle de cette version officielle, un site Web a été conçu pour la thèse et est accessible à l’adresse suivante : https://paume.page. / Noué autour de la question de la matérialité de l’inscription, le présent travail de recherche-création vise à comprendre comment les réalités matérielles s’agencent et font émerger les réalités culturelles de la littérature, soit comment le fait littéraire est une composition de rapports déterminée par les caractéristiques du support, qu’on le nomme média, machine ou plus largement environnement d’écriture. Qu’il s’agisse de la nouvelle architecture de l’information qu’implémente le Codex, de la plume que Flaubert taillait comme processus rituel de création, de la « délicate » machine à écrire d’un Nietzsche condamné à l’aveuglement, ou de l’ambiguïté des termes computer et « typewriter » qui peuvent autant désigner les femmes qui utilisaient des machines spécifiques que les machines en elles-mêmes, ces échos d’une culture littéraire sont autant de témoignages de l’importance des incidences matérielles dans l’écriture et dans le geste d’inscription en tant que tel. Où s’arrête la détermination de l’écriture ? Où se pose la frontière entre elle et le reste du monde ? dans nos cadres formatés, nos pratiques propres, ou nos regards ? Au travers d’études théoriques et d’explorations techniques, le corps de l’écriture sera décliné en cinq angles, cinq extensions d’une main qui souhaite saisir une épaisseur : fabrique, média, machine, page et matière. Cette thèse développe une méthodologie d’écriture propre qui ne distingue plus recherche et création pour redéfinir des contours du fait littéraire. / Tied up around the issue of the matter of inscription, this research-creation study aims to understand how concrete realities interact and lead to the emergence of a cultural phenomenon in literature, i.e., how the literature phenomenon is a composition of mattering defined by the specifications of the support, whether we call it a medium, a machine or, more broadly, a writing environment. From the new information architecture embodied by the Codex, to the writing feather of Flaubert ritualized as a creative process, to the “delicate” typewriter of a soon blind Nietzsche, or the ambiguity of the terms computer and typewriter, which may refer both to the women who used specific machines and to the machines themselves, these echoes of a culture of literature all illustrate the importance of material incidences in writing and in the very act of inscription itself. Where does the determination of writing end ? Where do we draw the line between it and the world beyond ? in our formated frames, our own practices, or the way we look at things? With theoretical analysis and technical exploration, the writing mattering will be investigated from five angles, five extensions of a hand that seeks to grasp depth : factory, media, machine, page and matter. This thesis sets out a writing methodology that no longer distinguishes research from creation, redefining the outlines of literature phenomenon.
8

Experimental and computer aided investigation of cutting process of brittle materials : магистерская диссертация / Экспериментальное и компьютерное исследование процессов резания хрупких материалов

Kharitonov, P. V., Харитонов, П. В. January 2016 (has links)
This master thesis work was aimed to enhance the computer aided modeling of cutting processes for hard brittle materials in optical and microelectronic industry. The parametric computer model of scribing the brittle wafer by diamond tool was developed using ANSYS APDL language and quasi-static conditions of treatment. Scribing of glass plates was realized by conic diamond tool on Roland CNC machine with different cutting parameters. Some experiments were made with coated glass plates. The surface quality of scribed plates was analyzed using AXIO ZEISS confocal microscope. The developed computer model enables predicting the defects zones in scribed brittle plate and searching the optimal cutting parameters and tool geometry. / Данная магистерская диссертация направлена на внедрение компьютерного моделирования технологических процессов резания применитльно к твердым хрупким материалам в оптической и электронной индустрии. Создана параметрическая компьютерная модель процесса скрайбирования алмазным инструментом для хрупкой пластины с использованием языка программирования ANSYS APDL в рамках квазистатического приближения. Скрайбирование стеклянныхз пластин было произведено коническим инструментом на станке с ЧПУ марки Roland с различными параметрами режима резания. Часть экспериментов проведена на пластинах с покрытием. Качество поверхности после скрайбирования было исследовано с помощью конфокального микроскопа AXIO ZEISS. Построенная компьютерная модель позволяет прогнозировать зону дефектности в скрайбированных хрупких пластинах и оптимизировать параметры режима резания, а также геометрию режущего инструмента.

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