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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.
11

Metallersättning inom byggbranschen

Eriksson, Magnus, Karlsson, Felix January 2006 (has links)
In this paper the possibilities to replace metal with plastic in products for the building industry were looked into. The first part was a market examination where several suitable products were found. After evaluation the door latch for in-house doors was selected to be re-designed to better suit the properties of plastic. New types of mechanisms were designed with different functions that use the benefits of plastic materials. Models of these mechanisms were developed to evaluate their function. The components in the different mechanisms were adapted for manufacturing with injection moulding. To confirm that the plastic material could handle the appearing stresses calculations on the most vulnerable parts were carried out. The result of the re-design process was three types of door latches that all fit in the doors standard cut-out. Model Classic is similar to the existing mechanism but the number of components is less than half and assembly and manufacturing is simplified. Model Magneto uses a magnet to move the locking part when the door is closed. Opening and locking is the same as Classic. Model Push/Pull uses a pushing or pulling motion to open the door depending on which side it is operated from. / I arbetet undersöktes ersättning av metallprodukter med plast inom byggindustrin. Första delen är en enkel marknadsundersökning där produkter som kan vara lämpliga och lönsamma att ersätta söks. Marknadsundersökningen ledde till att flera lämpliga produkter hittades och efter sållning valdes dörrmekanismen till innedörrar för vidareutveckling. I den andra delen som kallas Re-design har dörrmekanismen omkonstruerats och en ny funktion har utvecklats för att passa för tillverkning i plast och för att kunna dra nytta av de fördelar som plastmaterialet erbjuder. Efter idégenerering och sållning har modeller byggts för att testa funktioner. Därefter anpassades de utvalda mekanismerna för tillverkning med formsprutning. Beräkningar av mekanismens mest belastade delar utfördes i beräkningsprogrammet Abaqus. Arbetet resulterade i tre varianter av innerdörrsmekanismen som alla passar i dörrens standarduttag, dessa fick namnen Classic, Magneto och Push/pull. Classic har samma funktion som den existerande varianten men antalet delar är mindre än hälften och monteringen och tillverkning är enklare. Magneto liknar i stor utsträckning Classic men vid öppen dörr ligger kolven jämns med dörren och dras in i låsblecket av en magnet istället för av en fjäder som i Classic. Push/pull har en annorlunda öppningsfunktion där drag/tryck används för att öppna dörren istället för en vridrörelse.
12

Photochromic molecules in polymer switch diodes

Tai, Feng-i January 2006 (has links)
<p>Photochromism has been investigated extensively during recent years. The large interest for information storage in memory applications is associated with the bi-stable character of the photochromism phenomena. In molecular photochromics, two isomers with different absorption spectrum can be obtained according to the specific wavelength of the light exposure. This reversible transformation process can be considered as optical writing/erasing step of a memory.</p><p>Here we first report the absorption spectra of solid-state films based on the blends consisting of PC molecules, the spirooxazine 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3’-[3H]phenanthr[9,10-b](1,4)oxazine] (PIII, Sigma-Aldrich, 32,256-3) and a polymer matrix host, poly(2-methoxy-5(2’-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV). The bi-stability in conjugated polymer matrix is studied by following the time evolution of the optical properties of the blends.</p><p>Thereafter, the electrical performance of PC-polymer diodes is characterized and reported. While the PIII molecules in the blend bulks are switched to their low energy gap state, forming external energy levels above the valence band of MEH-PPV, the injected charges (hole-dominated) will be trapped by the low energy gap isomer of PIII and that leads to current modulation. PIII molecules can be switched between two energy gap states upon the photo-stimulation, and the I-V characteristics of the device can also be controlled reversibly via the photoisomerization. The retention time of the diode’s electrical switching fits quite well with the absorption characteristics of the blend films; this correspondence builds a good link between the film property and the device behavior.</p><p>Furthermore, we observed a two-trap system in the blend diodes from the I-V curves, and a model is proposed which can explain the schematic concept of the trap-limited current modulation. To combine the knowledge and information from the investigations above, we tested a novel device design based on a bi-layer of the PC and polymer materials, and the promising result for future work is presented in the end.</p>
13

Biomass Briquettes in Malawi

Faxälv, Olle, Nyström, Olof January 2007 (has links)
<p>In Malawi 2.5 % of the forest disappears each year. The use of firewood and charcoal, deriving from forest resources,</p><p>accounts for about 99 % of the household energy demand in Malawi and is a cause to the deforestation. The Government of</p><p>Malawi recently launched a programme called Promotion of Alternative Energy Sources Programme (PAESP) with the aim</p><p>to reduce the use of firewood and charcoal. One of the fuels included in the programme is the biomass briquette. The aim</p><p>with this study is to evaluate the viability of biomass briquettes as a sustainable alternative energy source to firewood and</p><p>charcoal for households in Malawi.</p><p>Research for the study was carried out during three months in Malawi. Visits were made to a number of briquette</p><p>production sites to study the manufacturing methods and to collect briquette samples. The briquettes were tested using</p><p>various methods and then compared with results for firewood and charcoal.</p><p>At the moment various production methods are used in Malawi, with a high difference in technical complexity and cost.</p><p>Machines produced from wood using very basic mechanics can apply similar pressure as more advanced metal pressers.</p><p>They also seem to be better suited than those made of metal, in terms of price and availability.</p><p>The majority of the briquette producers in Malawi use waste paper as base material. Although the paper briquettes are good,</p><p>other raw materials will be needed if the production is supposed to be significantly increased.</p><p>The briquettes burn well using the most common stoves in Malawi, including the commonly used charcoal stove. While</p><p>firewood is cheaper to use than other available fuels, the briquettes seem to be able to compete with the fuel costs for</p><p>charcoal.</p>
14

Vad händer när mode påverkar möbeldesign? : En kollektion strandmöbler och badkläder

Lindahl, Veronica January 2007 (has links)
<p>Rapporten beskriver ett designprojekt, som är en del av examensarbetet på 15p, Vad händer när mode påverkar möbeldesign? En kollektion strandmöbler och badkläder, utfört av Veronica Lindahl, avgångsstudent på utbildningsprogrammet möbeldesign på Carl Malmsten, Centrum för Träteknik & Design vid Linköpings universitet. Syftet med denna rapport är att beskriva processen av detta examensarbete.</p><p>Valet av produkter tog avstamp från min bakgrund i Halmstad. En möbel för stranden och något att ha på sig. Att koppla samman mode och möbeldesign tilltalar mig. Målet var att produkterna skulle komplettera och inspirera varandra. Att tänka på hur produkterna skulle presenteras var också en del i arbetet.</p><p>Upplägget i denna rapport är enligt ordningen i min designprocess. Det börjar med en insamlingsetapp. Efter detta följer en lång skissetapp, därefter material, tillverkning och slutligen en resultatanalys med tankar och reflektioner över vad jag kommit fram till.</p><p>Arbetet startade med samtal med handledaren Daniel Östman, där vi diskuterade val av examensarbete samt vad jag ville få ut av arbetet. Jag valde att göra ett projekt med mig som uppdragsgivare, eftersom det är så jag vill arbeta i framtiden.</p><p>Ledorden i mitt arbete har varit modedesigns påverkan på möbeldesign, en möbel för stranden och något att ha på sig, trä och tyg, material som klarar utomhusklimatet.</p><p>Resultatet är en funktionell, bärbar strandstol med två lägen som är lätt, går att fälla ihop och kan bäras på ryggen. Detta är en produkt som jag skulle vilja se på stranden.</p><p>Detsamma gäller badplaggen, de väcker nyfikenhet och är ett mer påklätt badmode.</p><p>Vid presentationen av produkterna använde jag mig av en stiliserad strand som gav en känsla av hur produkterna skulle användas i den miljö de var avsedda för.</p><p>I framtiden vill jag arbeta med att kombinera modeskapande och möbeldesign. Jag har upptäckt många intressanta möjligheter och uppslag i vad som händer när mode påverkar möbeldesign.</p>
15

Arbetsmöbel för ungdomar : Beskrivning av designprocessen i ett samarbete med IKEA

Leckström, Anna January 2007 (has links)
<p>Rapporten beskriver ett designprojekt, utfört som en del av examensarbetet på</p><p>15 HP, jag utfört som avgångsstudent på möbeldesignprogrammet vid Carl Malmsten Centrum för Träteknik & Design.</p><p>Från Ronnie Runesson, produktutvecklare på IKEA of Sweden, fick jag ett uppdrag, ett reellt projekt att arbeta med. Projektet handlade om att ta fram ett koncept på en ny typ av arbetsmöbel för ungdomar i åldersgruppen 12 – 18 år.</p><p>Målet med projektet var att, förutom att leverera ett fungerande koncept till IKEA, sätta min designmetodik på prov med hjälp av ett konkret designprojekt samt att vid projektets slut analysera den.</p><p>Rapporten har en beskrivande karaktär där jag berättar om de olika etapper arbetet utförts efter: Etapp 1- Koncept- och instuderingsetapp, Etapp 2- Vidareutvecklingsetapp, Etapp 3- Konkretisering av produkt. Beskrivningen förljer en kronologisk ordning för att underlätta läsarens förståelse för designprocessens gång.</p><p>Rapporten illustreras av ett fyrtiotal bildfigurer som visar delar ur mitt skiss- och gestaltningsarbete.</p><p>Rapporten avslutas med en analys av projektet samt den designmetodik jag använt mig av.</p> / <p>This report describes a design project (within a graduation project worth 15 points) that I completed during my final year as a student in the furniture design program at the Carl Malmsten Centre for Wood Technology and Design.</p><p>I received a commission from Ronnie Runesson, product developer at IKEA of Sweden, to develop an actual project to work with. The project was about creating a concept for a new type of desk for adolescences between the ages of 12 and 18.</p><p>The aim of the project was to, apart from deliver a working concept to IKEA, try out my design methodology with the aid of a concrete design project and at the end of the project create an analysis of it.</p><p>The character of the report is descriptive and in it I describe the different phases I worked with: Phase 1- Concept and Research Phase, Phase 2- Further Development Phase,</p><p>Phase 3- Realisation of Product. To facilitate the reader’s understanding of the design process the description follows a chronological order.</p><p>The report contains some forty images, showing parts of my sketch work.</p><p>The report ends with an analysis of the project and the design methodology I used.</p>
16

Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach

Bratberg, Johan January 2005 (has links)
The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. This information is also the basis for improving the properties or designing new alloys by controlling the amount of alloying elements. Thermodynamic calculations together with a thermodynamic database is a very powerful and important tool for alloy development of new tool steels and high-speed steels. By thermodynamic calculations one can easily predict how different amounts of alloying elements influence on the stability of different phases. Phase fractions of the individual phases and the solubility of different elements in the phases can be predicted quickly. Thermodynamic calculations can also be used to find optimised processing temperatures, e.g. for different heat treatments. Combining thermodynamic calculations with kinetic modelling one can also predict the microstructure evolution in different processes such as solidification, dissolution heat treatments, carbide coarsening, and the important tempering step producing secondary carbides. The quality of predictions based on thermodynamic calculations directly depends on the accuracy of the thermodynamic database used. In the present work new experimental phase equilibria information, both in model alloys containing few elements and in commercial alloys, has been determined and was used to evaluate and improve the thermodynamic description. This new experimental investigation was necessary because important information concerning the different carbide systems in tool steels and high-speed steels were lacking. A new thermodynamic database for tool steels and high-speed steels, TOOL05, has been developed within this thesis. With the new database it is possible to calculate thermodynamic properties and phase equilibria with high accuracy and good reliability. Compared with the previous thermodynamic description the improvements are significant. In addition the composition range of different alloying elements, where reliable results are obtained with the new thermodynamic database, have been widened significantly. As the available kinetic data did not always predict results in agreement with new experiments the database was modified in the present work. By coupling the new thermodynamic description with the new kinetic description accurate diffusion simulations can be performed for carbide coarsening, carbide dissolution and micro segregation during solidification. / QC 20100929
17

Aktivitetsbassäng i FHC Laholmskommun - tillståndsanalys

Senagic, Aida January 2010 (has links)
Simbassängen i Folkhälsocentrum i Laholm har drabbats av skador. Läckage i skvalprännorna har orsakat problem i de övriga konstruktionsdelarna. Laholmskommun har år 2002 vidtagit akuta åtgärder i hopp om att stoppa läckage och förebygga ännu större skador. Reparationsarbetet utfördes och efter två år konstaterades fortsatt läckage.För att kunna bedömma skadornas omfattning och orsak utförs en tillståndsbedömning av befintlig konstruktion. Tillståndsbedömningen kommer att ligga till grund för val av reparationsmetoder och reparationsomfattning. Det största problemet är armeringskorrosion föranled av karbonatisering och kloridinträngning. Hela konstruktionen befinner sig i en väldigt aggressiv miljö som accelererar hela nedbrytningsprocessen. Genom att göra okulärbesiktning och laboratorieanalys har jag kommit fram till att skadorna är omfattande och reparationsarbeten kommer att vara därefter.
18

Arbetsmöbel för ungdomar : Beskrivning av designprocessen i ett samarbete med IKEA

Leckström, Anna January 2007 (has links)
Rapporten beskriver ett designprojekt, utfört som en del av examensarbetet på 15 HP, jag utfört som avgångsstudent på möbeldesignprogrammet vid Carl Malmsten Centrum för Träteknik &amp; Design. Från Ronnie Runesson, produktutvecklare på IKEA of Sweden, fick jag ett uppdrag, ett reellt projekt att arbeta med. Projektet handlade om att ta fram ett koncept på en ny typ av arbetsmöbel för ungdomar i åldersgruppen 12 – 18 år. Målet med projektet var att, förutom att leverera ett fungerande koncept till IKEA, sätta min designmetodik på prov med hjälp av ett konkret designprojekt samt att vid projektets slut analysera den. Rapporten har en beskrivande karaktär där jag berättar om de olika etapper arbetet utförts efter: Etapp 1- Koncept- och instuderingsetapp, Etapp 2- Vidareutvecklingsetapp, Etapp 3- Konkretisering av produkt. Beskrivningen förljer en kronologisk ordning för att underlätta läsarens förståelse för designprocessens gång. Rapporten illustreras av ett fyrtiotal bildfigurer som visar delar ur mitt skiss- och gestaltningsarbete. Rapporten avslutas med en analys av projektet samt den designmetodik jag använt mig av. / This report describes a design project (within a graduation project worth 15 points) that I completed during my final year as a student in the furniture design program at the Carl Malmsten Centre for Wood Technology and Design. I received a commission from Ronnie Runesson, product developer at IKEA of Sweden, to develop an actual project to work with. The project was about creating a concept for a new type of desk for adolescences between the ages of 12 and 18. The aim of the project was to, apart from deliver a working concept to IKEA, try out my design methodology with the aid of a concrete design project and at the end of the project create an analysis of it. The character of the report is descriptive and in it I describe the different phases I worked with: Phase 1- Concept and Research Phase, Phase 2- Further Development Phase, Phase 3- Realisation of Product. To facilitate the reader’s understanding of the design process the description follows a chronological order. The report contains some forty images, showing parts of my sketch work. The report ends with an analysis of the project and the design methodology I used.
19

Slag inclusion formation during solidification of steel alloys and in cast iron

Adolfi, Sofia January 2007 (has links)
<p>This thesis explores the formation of segregation and inclusions during solidification of steel and cast iron. A better understanding of the formation mechanism should result in decreasing fraction of defects during solidification of ingot and strand material.</p><p>Density driven macrosegregation was studied both experimentally and theoretically to see the effect of channel segregation on the total segregation. Formation of these pencil-like segregations is due to natural convection in the solidifying metal caused by liquid enrichment of elements with lower density compared to the bulk. It is suggested to change the composition to compensate for this density difference.</p><p>Inclusion precipitation can be finite by limitations in segregation. Saturated liquid is found in the last solidified areas, often between dendrites. Here the enrichment of the liquid is possible due to microsegregation. Meanwhile crystals form and solidify the elements with low solubility in the solid is pushed out in the remaining liquid. Soon the liquid is saturated to the level where spontaneous formation of inclusions occurs. Microstructure studies by aid of SEM and micro-probe measurements are analysed to find at what point during solidification process the inclusions start to form. In steel making this formation has a detrimental effect on the mechanical properties in contrary to the production of nodular cast iron where the inclusions have a beneficial effect on the graphite formation.</p><p>Inoculation of cast iron aims at reaching higher number density of graphite nodules, nodule morphology modification and control of nodule distribution during solidification. Late precipitation of nucleation sites has shown to have a positive impact on preventing chill. To find the most potent inoculation agent different additives were tested. Special effort has been made to analyse the effect of oxides and sulphides as nucleation sites.</p>
20

Biomass Briquettes in Malawi

Faxälv, Olle, Nyström, Olof January 2007 (has links)
In Malawi 2.5 % of the forest disappears each year. The use of firewood and charcoal, deriving from forest resources, accounts for about 99 % of the household energy demand in Malawi and is a cause to the deforestation. The Government of Malawi recently launched a programme called Promotion of Alternative Energy Sources Programme (PAESP) with the aim to reduce the use of firewood and charcoal. One of the fuels included in the programme is the biomass briquette. The aim with this study is to evaluate the viability of biomass briquettes as a sustainable alternative energy source to firewood and charcoal for households in Malawi. Research for the study was carried out during three months in Malawi. Visits were made to a number of briquette production sites to study the manufacturing methods and to collect briquette samples. The briquettes were tested using various methods and then compared with results for firewood and charcoal. At the moment various production methods are used in Malawi, with a high difference in technical complexity and cost. Machines produced from wood using very basic mechanics can apply similar pressure as more advanced metal pressers. They also seem to be better suited than those made of metal, in terms of price and availability. The majority of the briquette producers in Malawi use waste paper as base material. Although the paper briquettes are good, other raw materials will be needed if the production is supposed to be significantly increased. The briquettes burn well using the most common stoves in Malawi, including the commonly used charcoal stove. While firewood is cheaper to use than other available fuels, the briquettes seem to be able to compete with the fuel costs for charcoal.

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