• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 379
  • 361
  • 181
  • 85
  • 51
  • 35
  • 28
  • 21
  • 19
  • 13
  • 13
  • 10
  • 8
  • 5
  • 5
  • Tagged with
  • 1323
  • 286
  • 214
  • 143
  • 139
  • 133
  • 126
  • 109
  • 105
  • 99
  • 91
  • 79
  • 75
  • 69
  • 62
  • 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.
131

Study on Forming Limit of Tubes

Lin, Jui-Chang 23 July 2003 (has links)
ABSTRACT The objective of this study is to establish the Forming Limit Diagram (FLD) of tubes. An experimental system of tube hydroforming, the electrical chemical etching method and the image process system are used to carry out the sheet metal forming test and the hydraulic bulge-forming test of annealed aluminum alloy tubes. Furthermore, Hill¡¦s new yield criterion is also used to predict the Forming Limit Curves of sheets. The predicted forming limit diagrams are compared with experimental data. The forming limit diagrams of tubes are coincident with those of sheets. Also, the predicted forming limit curves by Hill¡¦s new yield criterion agree quite well with those by experiments. Therefore, Hill¡¦s new yield criterion can be used to establish the forming limit curves of sheets or tubes.
132

Al-Au-Cu and Al-Au-Pd phase diagram study using diffusion couples

Li, Jyun-lin 21 July 2008 (has links)
none
133

Causal analysis and resolution for software development problems

Liang, Ting-wei 04 July 2009 (has links)
In recent years, it has to spend lots of time and effort to get the certification of CMMI. Therefore, everyone is looking to tools or methods for speeding up the CMMI certification. CMMI level five, causal analysis and resolution, is an important issues for all industries. In the process of software development, we have to identify the causes for defects at first. Then, it uses a systematic approach to sum up the necessary causes for software defects in order to help managers make better decisions and develop action items. With no doubt, it is a very important issue in the process of software development. This study aims to explore the subject of using the methods of causal analysis and resolution to solve the problems of software defects. Through the implementation of CAR, we can determine the root causes of defects and avoid importing defects to products. This study focus on the implementations of CAR and it proposes the methods, procedures and management forms. Moreover, this study will introduce the Mill¡¦s methods for causal reasoning used in the structure of CAR. Therefore it can help managers with a better way to sum up the causes for defects. The study uses case study method. Firstly, it connects the company for data collection of cause and effect diagram and combines the Mill¡¦s methods to inductive causal and analysis. Then it arranges interviews with the company managers to identify the necessary causes of defects. Finally, it helps the company develop action items in order to achieve the causal analysis and resolutions in the process of software development.
134

Polymorphism of sulfur: Structural and Dynamical Aspects

Crapanzano, Laura 20 June 2006 (has links) (PDF)
Cette thèse est une contribution à l'étude du polymorphisme du soufre à l'état solide et à l'état liquide avec, en particulier un examen des transitions liquide-liquide. <br /><br />Une introduction sur le polymorphisme dans les matériaux simples conduit à faire le choix d'étudier le soufre et on présente l'état des connaissances actuelles sur le diagramme P T du soufre. Puis on décrit les dispositifs haute pression; enclume diamant et presse à grand volume, mis en place à l'ESRF pour réaliser des études structurales ou dynamiques in situ, ainsi que les techniques d'étude de la structure et de la dynamique ; diffraction X, diffusion Raman, diffusion X inélastique utilisés pour ce travail. <br /><br />La partie suivante expose les résultats obtenus sur la structure des différents allotropes du soufre. Grâce à la possibilité de mesures in situ avec un flux intense et à l'utilisation conjointe de la diffraction X et de la diffusion Raman il a été possible de caractériser la structure de phases à l'équilibre et de construire d'un nouveau diagramme de phases du soufre en pression et température. <br /><br />La dernière partie concerne les résultats obtenus sur la dynamique du soufre liquide autour de la transition de polymérisation. On caractérise ainsi, aux basses températures, un liquide moléculaire classique dont la dynamique est celle des molécules S8. Aux plus hautes températures une solution de polymères présente encore le mode à haute fréquence correspondant aux molécules S8 mais aussi un autre, à basse fréquence, qui correspond à des fragments de chaînes interconnectes.
135

Kvalitetsbristkostnader i materialanskaffningsprocessen : -En fallstudie på Holtab AB

Lindahl, David, Simon, Gustafsson January 2015 (has links)
Bakgrund: Intresset för processer och framförallt utveckling eller förbättring av processer har på senare år ökat. Detta kan ha sin grund i att många företag har behållit föråldrade rutiner och processteg samtidigt som verksamheten utvecklats, något som resulterat i onödigt komplexa processer som påverkat företags ekonomiska och praktiska prestationer. En annan orsak kan vara att företagsklimatet blivit allt tuffare. En process som under senare år fått ökat intresse inom företagvärlden samt kommer sätta stor prägel på denna uppsats är materialanskaffningsprocessen. Materialanskaffning beskrivs som en process innefattande samtliga de aktiviteter som krävs för att säkerställa att material tillförs en organisation. Syfte: Syftet med denna uppsats är inledningsvis att kartlägga samt identifiera brister i Holtabs materialanskaffningsprocess. Vidare är syftet att komma med eventuella förslag till hur Holtab kan reducera kvalitetsbristerna i materialanskaffningsprocessen för att på så sätt minska företagets kvalitetsbristkostnader. Metod: Denna uppsats är en fallstudie på Holtab AB. Studiens metod är i huvudsak kvalitativ med kvantitativa inslag. Uppsatsen har vidtagit en deduktiv forskningsansats med ett positivistiskt synsätt. Det empiriska materialet samlades in genom semi-strukturerade och ostrukturerade intervjuer samt en kvalitetscirkel. Vidare har uppsatsens teoretiska referensram baseras på litterära källor samt vetenskapliga artiklar. Slutsatser: Holtabs materialanskaffningsprocess har beskrivits genom en processkartläggning. Vidare har författarna identifierat materialanskaffningsprocessens kvalitetsbristkostnader samt dess orsaker. Avslutningsvis har författarna tillsammans med medarbetare på Holtab AB tagit fram förbättringsförslag till de brister som identifierats. / Background: In the recent years, the interest of processes and especially the development or improvement of processes has increased. This may be because many companies have kept obsolete routines and process steps while the businesses have developed. As a result the processes have become unnecessarily complex and affect the companies’ financial and operational performance. Another reason may be that the business environment has become tougher. A process that in the recent years has received an increased interest in the business world and will put its mark on this essay is the material procurement process. Material procurement is described as a process including all activities necessary to ensure that all the required material is supplied to an organization.  Purpose: The purpose of this essay is initially the map and identifies poor quality in Holtabs material procurement process. Further the purpose is to present suggestions on how Holtab can reduce their poor quality in order to reduce the company’s cost of poor quality. Method: The following essay is a case study on Holtab AB. The study is mainly performed in the form of a qualitative study which is supplemented by some quantitative elements. The study emanated from a deductive standpoint with a positivistic approach. The empirical data were collected by the usage of semi-structured and unstructured interviews as well as a quality circle. Further the theoretical framework was collected by literature and scientific articles.   Conclusions: Holtabs material procurement process have been defined and mapped through process mapping. Furthermore have the authors identified cost of quality deficiencies and the causes behind said deficiencies. Finally the authors have derived and presented suggestions for improving Holtabs material procurement process by reducing the quality deficiencies and therefore the related costs.
136

XLPE-cable Production Optimization : Setup time Reduction at Armoring line

Hedlund, Björn January 2014 (has links)
At ABB’s high voltage cable factory in Karlskrona, there is a line production that is regarded as a bottleneck. The production rate at this workplace as well as the large variations of setups has created two major problems. The first problem is that it has become difficult for the planning department to determine the lead times for delivery to the customers. The other problem is that the long setup times has made this line production the bottleneck of the whole production. The factory at ABB HVC includes a number of line productions, where each line has their own purpose and value adding processes. The armoring line AR50 that this project has the focus to improve has the last value adding processes for the factory’s main product. The factory’s main product is the Cross-Linked Polyethylene cable, shortened XLPE. There are several different advantages with the XLPE-cable system. First of all they are maintenance-free and environmentally friendly. The main reason that the XLPE-cable is environmentally friendly is because it have low electrical losses. Since the submarine cables are underground the cables are invisible and not effected by weather conditions. This project implements the method SMED as well as various methods from the LEAN transcript in order to reduce the setup times and create a more stable and effficient production. An Ishikawa diagram were used in order to determine the root causes of the problems. Later both technical and management solutions were proposed and implemented. The project has concluded impressive results regarding setup time reduction and annual cost savings. It also enlightens the large potential for further improvement. This project will be continued during the year of 2014 in order to implement the proposed solutions. The future improvements are not just technical but also related to management and group dynamics.
137

First principles calculations of thermodynamics of high temperature metal hydrides for NGNP applications

Nicholson, Kelly Marie 21 September 2015 (has links)
In addition to their potential use at low to moderate temperatures in mobile fuel cell technologies, metal hydrides may also find application as high temperature tritium getterers in the U.S. DOE Next Generation Nuclear Plant (NGNP). We use Density Functional Theory to identify metal hydrides capable of sequestering tritium at temperatures in excess of 1000 K. First we establish the minimum level of theory required to accurately capture the thermodynamics of highly stable metal hydrides and determine that isotope effects can be neglected for material screening. Binary hydride thermodynamics are largely well established, and ternary and higher hydrides typically either do not form or decompose at lower temperatures. In this thesis we investigate anomalous systems with enhanced stability in order to identify candidates for the NGNP application beyond the binary hydrides. Methods implemented in this work are particularly useful for deriving finite temperature phase stability behavior in condensed systems. We use grand potential minimization methods to predict the interstitial Th−Zr−H phase diagram and apply high throughput, semi-automated screening methodologies to identify candidate complex transition metal hydrides (CTMHs) from a diverse library of all known, simulation ready ternary and quaternary CTMHs (102 materials) and 149 hypothetical ternary CTMHs based on existing prototype structures. Our calculations significantly expand both the thermodynamic data available for known CTMHs and the potential composition space over which previously unobserved CTMHs may be thermodynamically stable. Initial calculations indicate that the overall economic viability of the tritium sequestration system for the NGNP will largely depend on the amount of protium rather than tritium in the metal hydride gettering bed feed stream.
138

Development of Greenhouse Gas Mitigation Options for Alberta’s Energy Sector

Subramanyam, Veena Unknown Date
No description available.
139

Improvements for Waran-patients in Finspång / Förbättringsarbete för Waran-patienter i Finspång

Lennartsson, Emma January 2014 (has links)
Närsjukvården i Finspång har idag 540 patienter som är i behov av, och behandlas med det blodförtunnande läkemedlet Waran. Läkemedlet ges till de som drabbats av blodpropp (bentrombos/lungemboli), förmaksflimmer eller har klaffproteser. Patienterna besöker i stor del den mottagning som finns på Finspångs Lasarett men det finns de som av olika anledningar inte kan ta sig till mottagningen, främst beroende på att de lider av andra sjukdomar som gör att de har svårt att förflytta sig längre sträckor. Därför besöks de i hemmet och där tar DS de prover som behövs. Grunden till projektet Närsjukvården i Finspång-Förbättringsarbete för Waran-patienter i Finspång, är att hitta andra lösningar på hur situation kan förändras och därigenom också förbättras för de patienter där provtagningen måste ske i hemmet. Projektet har resulterat i en analys kring fyra olika scenarier som alla medförde förbättringar både vad gäller kostnader, transporter och tid. För att få en inblick i vilka scenarier som användes beskrivs de nedan. Scenario 1a visar en bild över situationen som den såg ut när fösta kartläggningen skedde i och med det första besöket på Närsjukvården i Finspång. Scenario 1b visar en bild över hur hanteringen av patienterna fungerar vid andra kartläggningen på Närsjukvården i Finspång. Här har vissa patientbesök redan ersatts med att patienterna själva, med hjälp av CoaguChek, genomför kontroll av sitt INR-värde. Scenario 2 liknar scenario 1a men istället för en distriktssköterska (DS) är det en biomedicinsk analytiker (BMA) som besöker patienterna och genomför provtagningen. Scenario 3 ger en bild över hur det ser ut när det är en DS som gör hembesöken men att provtagningen nu sker med hjälp av CoaguChek. Scenarier har därefter analyserats sinsemellan med fördelar och nackdelar och projektet har kommit fram till den lösning som projektet anser vara den bäst lämpade för hanteringen av Waran patienterna.
140

Matrix Integrals : Calculating Matrix Integrals Using Feynman Diagrams

Friberg, Adam January 2014 (has links)
In this project, we examine how integration over matrices is performed. We investigate and develop a method for calculating matrix integrals over the set of real square matrices. Matrix integrals are used for calculations in several different areas of physics and mathematics; for example quantum field theory, string theory, quantum chromodynamics, and random matrix theory. Our method consists of ways to apply perturbative Taylor expansions to the matrix integrals, reducing each term of the resulting Taylor series to a combinatorial problem using Wick's theorem, and representing the terms of the Wick sum graphically with the help of Feynman diagrams and fat graphs. We use the method in a few examples that aim to clearly demonstrate how to calculate the matrix integrals. / I detta projekt undersöker vi hur integration över matriser genomförs. Vi undersöker och utvecklar en metod för beräkning av matrisintegraler över mängden av alla reell-värda kvadratiska matriser. Matrisintegraler används för beräkningar i ett flertal olika områden inom fysik och matematik, till exempel kvantfältteori, strängteori, kvantkromodynamik och slumpmatristeori. Vår metod består av sätt att applicera perturbativa Taylorutvecklingar på matrisintegralerna, reducera varje term i den resulterande Taylorserien till ett kombinatoriellt problem med hjälp av Wicks sats, och att representera termerna i Wicksumman grafiskt med hjälp av Feynmandiagram. Vi använder metoden i några exempel som syftar till att klart demonstrera hur beräkningen av matrisintegraler går till.

Page generated in 0.0284 seconds