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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.
31

Počítačová analýza obrazu z metody LBIC / Computer analyse of LBIC pictures

Štencel, Jakub January 2010 (has links)
This thesis is concerned with image picture analysis, especially with images obtained by diagnostic LBIC method. The individual defects occuring on solar cells are described in theoretical part, including methods which serve for making referential image. Furthermore, the creation of difference image is analysed, from whom the interferences will be evaluated. The aim of practical part is to focus on generation of algorithms which investigate the defects, and the description of application for program control is described in conclusion.
32

Transiente Methoden der Infrarot-Thermografie zur zerstörungsfreien Fehleranalytik in der mikroelektronischen Aufbau- und Verbindungstechnik

May, Daniel 10 March 2015 (has links)
In dieser Arbeit wurde eine neue fehleranalytische Methode zur industriellen Anwendung an neuen Technologien der Aufbau- und Verbindungstechnik entwickelt. Das Verfahren basiert auf der Wechselwirkung von thermischen Wellen und Defekten. Die Besonderheit ist dabei die Zerstörungsfreiheit, die Geschwindigkeit, das Auflösungsvermögen und die durch neueste IR-Detektoren erreichte Temperaturempfindlichkeit. Es wurden grundlegende Studien bezüglich Auflösung und parasitären Effekten bei der Anwendung unter industriellen Randbedingungen durchgeführt. Dabei wurde eine systematische Vorgehensweise bezüglich der Komplexität gewählt. Dies ermöglicht nun u.a. eine Vorhersage der zu erwartenden Prüfdauer zur Auflösung vergrabener Defekte, der Begrenzung der maximalen Anregungsimpulsbreite (bei gegebener Defekttiefe) und die quantitative Ermittlung des Einflusses einer Lackschicht. Methodisch kamen grundsätzlich Simulationen und vergleichende Experimente zum Einsatz. Es wurden spezielle Proben zur Isolierung und Klärung parasitärer Effekte verwendet. Letztlich konnte das Messsystem erfolgreich an industriellen Problemstellung demonstriert werden. Das entwickelte Messsystem zeichnet sich durch hohe Flexibilität aus. Verschiedene problemangepasste Anregungsquellen (interne und externe Anregung durch zahlreiche physikalische Effekte) kommen zum Einsatz. Das Messsystem besteht aus vier Hauptmodulen, der Differenzbild-Methode, der Impulsthermografie, und zwei Varianten der LockIn-Thermografie. Zusammen ist das System in der Lage, Voids, Delaminationen und Risse in verschiedenen Bereichen auch der modernen AVT sicher zu erkennen. Es werden dabei Temperaturauflösugnen bis zu 5 mK und laterale Auflösungen bis 17 µm erreicht. Diese Arbeit legt einen Grundstein für die Anwendung der thermischen Fehleranalytik in der Industrie, indem hier die Grenzen der IR-Messtechnik aufgezeigt und charakterisiert werden. / In this work a new failure analytical method for the industrial application of new technologies in electronic packaging has been developed. The developed method is based on the interaction of the thermal waves and defects. The special fature is non-destructive, speed, resolution and high temperature sensitivity due to latest IR-detectors. It fundamental studies regarding resolution and parasitic effects in the application were carried out cinsidering industrial conditions. Here, a systematic approach regarding the complexity has been selected. This now enables a prediction of the expected test period for detecting buried defects, limits for excitation pulse width (for a given defect depth) and the quantitative determination of the influence of parasitic paints. Methodically always simulations and comparative experiments were used. Simple samples for the isolation and purification of parasitic effects has been used. Finally, the measurement system has been successfully demonstrated on an industrial applications. The developed measurement system is characterized by high flexibility. Different problem-adapted excitation sources (internal and external excitation by numerous physical effects) are used. The measurement system currently consists of four main modules, the difference image method, the pulse thermography, and two variants of LockIn-thermography. Together, the system is capable of detecting voids, delaminations and cracks in various fields of electronic packageing. It will reach temperature resolutions up to 5 mK and lateral resolutions down to 17 µm. This work stes a foundation for the application of thermal failure analysis for industry by showing and charcterization the limits of IR imaging.
33

Aplikace povrchové defektoskopie při kontrole jakosti povrchu / Application of Flaw Detection Method for Surface Quality Inspection

Smutný, Daniel January 2010 (has links)
When processing materials, there are a number of factors which influence the final quality of products. The possibility of defects occurrence, both sub-surface and surface ones, is one of the factors. In the precision engineering production, the automotive, bearing or aerospace industry in particular, no level of defects is tolerable. The thesis deals with the causes and consequences of the occurrence of such defects, and the methods for their identification. For this purpose, a new contactless optical method for the fully automatic inspection of the surface defects has been developed by Mesing, spol. s r.o. In order to verify the performance of the aforementioned method, four specific products have been tested by the author using the method. Finally, there are examples of the successful implementation of the automatic machines, for a design of which the results of the model testing were utilized.
34

Defect Engineering

Steinegger, Thomas 10 July 2009 (has links) (PDF)
Die Kenntnisse über die zur Passivierung führenden Wechselwirkungen des Verunreinigungselements Cu mit EL2 und EL6 wurden dahingehend erweitert, dass ein Gültigkeitsbereich für die Messungen zur Bestimmung der konzentrationsproportionalen Messgröße der Defekte festgelegt wurde. Der Defekt EL6 ist das die 0.8 eV-PL-Emission bedingende und die Ladungsträgerlebensdauer determinierende Rekombinationszentrum. Die Lebensdauer wird durch mindestens ein weiteres Zentrum beeinflusst. Die atomare Struktur des EL6 wurde mit AsGa VAs und die des weiteren Zentrums mit Asi bestimmt. Mittels Wärmebehandlung kann die Ladungsträgerlebensdauer gezielt beeinflusst werden. Bei der Bildung und Annihilation sowie der Verteilung der Defekte EL2, EL6, VGa und der As-Ausscheidungen besteht eine wechselseitige Korrelation. Sowohl strukturelle Defekte als auch die Inkorporation von Dotierelementen, deren Atomradien deutlich kleiner sind als Ga und As, stellen beeinflussende Faktoren dar. Das Defekt-Transformations-Modell erklärt die Bildung wachstumsfähiger Keime einer As-Ausscheidung durch EL2 bzw. EL6 mit den sich in der ersten Koordingationssphäre befindenden As-Atomen. Das Gitterrelaxations-Modell ermöglicht die Interpretation der katalytischen Wirkung des Dotierelements C. Die Umsetzung dieser Ergebnisse bedeutet die Anwendung des Defect Engineerings im SI-LEC-GaAs.
35

Metodika testování podle mezinárodních praktik a standardů / Testing methodology according to international practices and standards

Králová, Iveta January 2012 (has links)
There are many methodologies in the field of software engineering that focus on the entire software development process. The software development process aims to provide a quality product that meets user requirements, and to deliver it on time as well as within budget. Testing is a tool for verifying the quality of software and serves as feedback in software development. Most software development methodologies are available only in English, they emphasize the actual software development and address testing only marginally. An accurately designed testing process however, may contribute to higher software quality and avoid potential problems resulting from the entire information system's failure. Current Czech methodology that focuses exclusively on testing has been developed either inside individual companies and thus is not accessible to the public, or is contained in graduate theses, where it was typically created by adapting and expanding the existing software development methodologies for testing within a particular company or team. The main objective of this thesis is to establish a methodology for testing in Czech, which is based on international practices and standards, which is not tailored to a specific organization and which can be used as guidance in defining test processes in various organizations, regardless of their specific focus. The proposed methodology is also implemented in the tool EPF Composer that enables administration of methodology and its publication in the form of the website. The thesis also pursues additional objectives. In order to verify the objective of developing a standardized testing methodology is met, the thesis strives to produce a subsequent evaluation methodology using a standardized process framework in order to improve the testing process as well as a summary detailing which areas may be the subject of further expansion methodology. The theoretical part of the thesis aims to evaluate software development methodologies in terms of testing, to provide an overview of standards related to testing and to describe selected standards, to clarify the purpose of certification in testing and to analyze the possibilities of utilizing materials to prepare for the ISTQB certification. The objectives were achieved by analyzing the available materials for ISTQB certification, analyzing software development methodologies, standards, the TMMi procedural framework and other resources that deal with testing as well as its methodologies and standards. The main contribution of this work is a testing methodology, which is based on the testing process as defined by the international organization ISTQB. It provides a methodological framework by interconnecting and expanding individual methodological elements. Elements of the methodology include working products, as specified by the methodology with respect to the IEEE 829 standard. The methodology does not depend on the needs of a particular company and may be easily adopted, managed and customized. It may be used as a starting point in creating a testing strategy in Czech companies focused on software development which are interested in approaching testing in compliance with international practices.
36

Fotoluminiscenční metody detekce defektů solárních článků / Solar cells photoluminescence defect detection methods

Vala, Zbyněk January 2009 (has links)
This thesis discusses modern methods for fast defect detection of solar cells. For the means of the defect classification, the technological production process of crystalline silicon solar cells is described. The defects are researched by the electroluminescence and prohtoluminescence methods. The Photoluminiscence method is improved by the posibility of using different wavelenght of excitacion sources. The range of using in industrial production is determined for the discussed methods.
37

Vliv teplotních závislostí luminiscence solárních článků / Influence of temperature dependence of luminescence solar cells

Koutný, Michal January 2010 (has links)
This work deals with determination defects in solar cells using non-destructive methods. Defects are determinating by electroluminescence method and microplasma method in temperature influence. Temperature will be changed by Peltier cells. By using this various temperatures during the testing we can receive more objective results thanks to simulated operation conditions.
38

Analytické metody solárních panelů a systémů / Analytic method of solar panel and systems

Kopunec, Vít January 2011 (has links)
The aim of the diploma work is to introduce analytical methods concerning solar panels and systems. Firstly, the attention is drawn to a principle of photovoltaic conversion including an explanation of photoelectric phenomenon as well as the issue of P-N junction considered to be the fundamental building block of a solar cell. With respect to the fact that the diploma work is to be focused on testing of solar panels and the identification of defects in solar cells, the work describes individual solar cells, solar panels as well as individual methods of defect identification. Secondly, the work includes sections dealing with the assessment of the measurement performed by using electroluminescence method as well as the measurement method of volt-ampere parameters. The last section of the work includes the assessment of solar panel aging after one-year performance using the electroluminescence measurement method.
39

On some reversal-invariant complexity measures of multiary words / O nekim reverznoinvarijantnim merama složenosti visearnih reči

Ago Balog Kristina 11 September 2020 (has links)
<p>We focus on two complexity measures of words that are invariant under the operation of reversal of a word: the palindromic defect and the MP-ratio.The palindromic defect of a given word w is dened by jwj + 1&nbsp;&nbsp; jPal(w)j, where jPal(w)j denotes the number of palindromic factors of w. We study innite words, to which this de&nbsp; nition can be naturally extended. There are many results in the literature about the so- called rich words (words&nbsp; of defect 0), while words of nite positive defect have been studied signicantly less; for some time (until recently) it was not known whether there even exist such words that additionally are aperiodic and have their set of factors closed under reversal. Among the rst examples that appeared were the so-called highly potential words. In this&nbsp; thesis we present a much more general construction,which gives a wider class of words, named generalized highly potential words, and analyze their signicance within the frames of combinatorics on words.The MP-ratio of a given n-ary&nbsp; word w is dened as the quotient jrwsj jwj ,where r and s are words such that the word rws is minimal- palindromic and that the length jrj + jsj is minimal possible; here, an n-ary word is called minimal-palindromic if it does not contain palindromic subwords of length greater than jwj n . In the binary case, it was proved that the MP-ratio is well-dened and that it is bounded from above by 4, which is the best possible upper bound. The question of well- denedness of the MP-ratio for larger alphabets was left open. In this thesis we solve that&nbsp; question in the ternary case: we show that the MP-ratio is indeed well-dened in the ternary case, that it is bounded from above by the constant 6 and that this is the best possible upper bound.</p> / <p>Izucavamo dve mere slozenosti reci koje su invarijantne u odnosu na operaciju preokretanja reci: palindromski defekt i MP-razmeru date reci.Palindromski defekt reci w denise se kao jwj + 1&nbsp;&nbsp; jPal(w)j, gde jPal(w)j predstavlja broj palindromskih faktora reci w. Mi izucavamo beskonacne reci, na koje se ova denicija moze prirodno prosiriti. Postoje mnogobrojni rezultati u vezi sa tzv. bogatim recima (reci cije je defekt 0), dok se o recima sa konacnim pozitivnim defektom relativno malo zna; tokom jednog perioda (donedavno) nije bilo poznato ni da li uopste postoje takve reci koje su,dodatno, aperiodi cne i imaju skup faktora zatvoren za preokretanje. Medu prvim primerima koji su se pojavili u literaturi su bile tzv. visokopotencijalne reci. U disertaciji cemo predstaviti znatno opstiju konstrukciju, kojom se dobija znacajno sira klasa reci, nazvanih uop stene visokopotencijalne reci, i analiziracemo njihov znacaj u okvirima kombinatorike na recima.MP-razmera date n-arne reci w denise se kao kolicnik jrwsj jwj , gde su r i s takve da je rec rws minimalno-palindromicna, i duzina jrj + jsj je najmanja moguca; ovde, za n-arnu rec kazemo da je minimalno-palindromicna ako ne sadrzi palindromsku podrec duzine vece od&nbsp; jwj n&nbsp; . U binarnom slucaju dokazano je da je MP-razmera dobro&nbsp; denisana i da je ogranicena odozgo konstantom 4, sto je i najbolja moguca granica. Dobra denisanost MP-razmere za vece alfabete je ostavljena kao otvoren problem. U ovoj tezi resavamo taj problem u ternarnom slucaju: pokazacemo da MP- razmera jeste dobro de-nisana u ternarnom slucaju, da je ogranicena odozgo sa 6, i da se ta granica ne moze poboljsati.<br />&nbsp;</p>
40

The Influence of Drawing Speed on Steel Wire Surface Quality / Draghastighetens påverkan på ståltrådens ytkvalitet

Viklund, Felicia, Lundin Bornström, Amanda January 2022 (has links)
Tråddragning är en kallbearbetningsprocess där tråd dras genom en dragsten, som plastiskt deformerar materialet och reducerar tvärsnittsarean. En viktig parameter i tråddragningsprocessen är draghastigheten - en ökad draghastighet kan förbättra produktiviteten, vilket är önskvärt för företaget Suzuki Garphyttan AB då efterfrågan på produkter har ökat. Dessutom är ökad produktivitet positivt i avseende med ekonomisk hållbarhet, men får inte ske på bekostnad av trådkvaliteten. En försämrad kvalitet kan leda till en större mängd skrot vilket är negativt utifrån ett miljömässigt hållbarhetsperspektiv. I detta examensarbete har åtta olika experiment utförts med syfte att undersöka hur ökad draghastighet och ett ökat vattentryck påverkar ytkvaliteten på kolstålet Oteva 75. Data i form av temperaturmätningar, ytjämnhet och djup av defekter har samlats in för att göra jämförelser och dra slutsatser mellan ökad draghastighet och ytkvalitet. Resultatet indikerar att det uppstår mindre variationer gällande ytjämnheten vid lägre hastigheter samt att djupet på repor inte har försämrats eller förbättrats i ett specifikt mönster vid ökade hastigheter. Med ett ökat vattentryck var djupet på repor minst vid mellersta hastigheten och ytjämnheten hade marginellt större variationer vid högre hastigheter jämfört med den lägsta. För att kunna dra generella slutsatser måste fler liknande experiment göras i framtiden. Variablerna måste observeras mer noggrant genom att till exempel använda samma maskin, samma smörjmedelsförhållanden och samma leverantör. Detta kan göras genom att testa samma trådring, i samma maskin. / Wire drawing is a cold-working process in which a wire is pulled through a drawing die, resulting in plastic deformation of the material and wire diameter reduction. One important parameter in the wire drawing process is the drawing speed. An increased drawing speed can improve productivity, which is desired for the company Suzuki Garphyttan AB due to the increased demand for products. Furthermore, improved productivity is positive in terms of economic sustainability, but cannot be at the expense of wire quality. Worsen quality may lead to increased amount of scrap which is negative from a perspective of environmental sustainability. In this master thesis, eight different experiments have been performed with the aim to examine how increased drawing speed-, and pressure of cooling water, affects the surface quality of the carbon steel Oteva 75. Data in terms of temperature measurements, surface roughness and depth of defects have been collected to make comparisons and conclusions between increased drawing speed and surface quality. The result indicates that there are less variations regarding the surface roughness at lower speeds than higher speeds. The depth of defects has not deteriorated or improved in a specific pattern at increased speeds. With increased water pressure, the depth of defects was smallest at the first speed increase and the surface roughness had marginally larger variations at the highest speed. To be able to draw general conclusions, more similar experiments must be done in the future. The variables involved need to be observed more carefully by, for example, using the same shaving equipment, the same lubrication conditions, and the same supplier. This can be done by testing on the same wire ring, in the same machine.

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