• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 415
  • 104
  • 95
  • 64
  • 58
  • 58
  • 23
  • 20
  • 20
  • 15
  • 12
  • 10
  • 8
  • 5
  • 5
  • Tagged with
  • 1018
  • 209
  • 129
  • 85
  • 66
  • 59
  • 56
  • 51
  • 48
  • 47
  • 42
  • 42
  • 38
  • 38
  • 38
  • 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.
21

Processing of All Cellulose Composites via an Ionic Liquid Route

Huber, Tim January 2012 (has links)
Newly developed all-cellulose composites (ACCs) can overcome the chemical incoherence between cellulose and other polymers by dissolution and regeneration of a portion of cellulose to create a chemically identical matrix phase. New “close to industry”-processing ways for ACCs were developed to create “thick” ACCs (>1 mm thickness) based on composite processes already used in the composite industry. The ionic liquid (IL) 1-Butyl-3-Methylimidazolium Acetate (BmimAc) is a strong solvent for both, native cellulose and cellulose II. The dissolution process is strongly depended on the temperature and viscosity of the IL-cellulose solution. Next to complete dissolution, rayon fibre can be dissolved partially to achieve the formation of a matrix phase in situ. The highly hydrophilic cellulose based materials show different amounts of shrinkage after composite processing when the coagulant necessary to regenerate the dissolved cellulose is removed by evaporative drying. Multilayered, “thick” composite laminates could be produced by a simple hand-impregnation of rayon and linen textiles with the solvent and partial dissolution of the cellulosic textiles. A solvent infusion process (SIP) based on vacuum assisted resin infusion was successfully developed to process ACCs. The application of pressure during SIP is crucial to achieve good interlaminar adhesion. The SIP based laminates showed improved tensile strength and stiffness compared to the hand impregnation process. An analysis of the processing parameters showed that the drying process used to remove the coagulant is important to achieve good fibre-matrix-bonding as harsh evaporative drying causes shrinkage induced cracks in the created matrix phase. Using ethanol as a coagulant instead of water reduced composite swelling and corresponding shrinkage, but leads to a strong reduction in crystallinity of the regenerated cellulose, as shown X-ray diffraction and solid state NMR measurements. Regeneration in distilled water, followed by drying at room temperature produced the best ACC laminate. The SIP based laminates showed high flexural and impact strength compared to other biocomposites. The composites were also found to be easily compostable especially compared to a PLA-rayon composite. The rayon fibre was processed on an ITA 3D rotary braiding machine, generally used for the processing of stronger and stiffer glass and carbon fibres. A rectangular profile was produced and analysed. The fibre strength and Young’s modulus were unaffected by the braiding process. The braid could be processed into an ACC by immersion in IL for 60 min at 100 °C. The so produced ACCs showed further improvements in tensile and impact strength due to improved through the thickness strength.
22

Numerical investigation of novel structures of nonlinear optical fibre loop mirrors including Bragg gratings

Hemingway, John-Paul J. January 1999 (has links)
No description available.
23

The development of a position sensitive gamma-ray detector

Lawton, Christopher David January 1998 (has links)
No description available.
24

Adidas, the All Blacks, and Maori Culture: Globalization and the Reformation of Local Identities

Goris, Michelle 03 October 2013 (has links)
As corporations transcend international borders new questions arise concerning the formation of identities. This study looks at adidas advertising campaigns "Bonded by Blood" and "Of This Earth" and how they represent and commodify Māori culture. "The Making" of "Bonded by Blood" is the video component for that campaign. The "Of This Earth" file is the TV commercial from 2007. Furthermore, this study looked at whether or not these advertisements are in fact reaffirming already established stereotypes about indigeneity and "Otherness." This thesis is informed by Stuart Hall's article "The Spectacle of the Other" as well as works by other scholars who discuss ideologies of Otherness, globalization, glocalization, mobility, and corporate sports sponsorship. The posters of each campaign as well as the video components were analyzed through textual analysis. The results show that patterns of cultural appropriation and reaffirmation of stereotypes do occur in the posters and videos of those campaigns. The two video components are included as supplementary files for this thesis. / 10000-01-01
25

Sleepsafe

Nilsson, Tobias, Johlin, Jeanette January 2007 (has links)
<p>Syftet med arbetet är att lösa problemet med det befintliga låset till spjälsängen Sesam, en säng anpassad för funktionshindrade småbarnsföräldrar som genom att ha grindar på fram-sidan gör det lätt även för en rullstolsburen eller muskelsvag person att komma åt. Problemet är dels att grindarna behöver lyftas upp för att öppnas, ett moment som kan vara svårt för en person med nedsatt muskelfunktion. Det andra problemet är att överliggaren är för lätt att öppna inifrån och har dålig hållfasthet.</p><p>Målet är att i samarbete med Mayday Aid AB ta fram ett lås som löser problemet.</p><p>Metod: </p><p>BAD, MAD, CAD, Benchmarking, Past- och real time studies.</p><p>Bakgrund: </p><p>Antalet föräldrar med funktionshinder ökar snabbt.2 Detta kan tyda på en attitydförändring med en ökad social integration och en naturlig förväntan att leva ett fullvärdigt liv. I deras syn på sig själva har de försökt avlägsna sig från rollen som vårdtagare och i stället ser de sig som självständiga individer med i stort sett samma behov, rättigheter och skyldigheter som alla andra. En vid sjukdomsbild har genomförts för att på bästa sätt tillmötesgå målgruppen vid utformningen av produkten.</p><p>Resultat:</p><p>Låset ”Sleepsafe” tillverkat av björkplywood som bevisligen minskar den kraft som behövs för att öppna grindarna. Mätningarna visade att det endast krävs 6.52 N med nya låsets konstruktion att jämföra med 19.99 N för den ursprungliga låskonstruktionen.</p><p>Diskussion:</p><p>Vi strävade efter att integrera hela låsningsmekanismen i en produkt för att slippa utföra flera moment vid öppnandet, men för att göra låset mer barnsäkert så monterades ett extra lås nedtill som då blir svårt för barnen att nå. Med nya gångjärn slipper man numera att lyfta hela grinden. Ett fantastiskt tillfälle gavs till att testa låset på de riktiga användarna på handikapp-mässan ”Leva och fungera” i Göteborg. Produkten justerades något efteråt. Med låsets nya konstruktion har problemen eliminerats och underlättar för användaren.</p>
26

Modeling and design of an electric all-terrain vehicle

Chevrefils, Adam R. 15 January 2009 (has links)
This thesis describes and evaluates the conversion of a conventional gasoline powered all-terrain vehicle (ATV) to an electric ATV. Preliminary studies are performed to obtain initial power and torque requirements for the vehicle. A detailed simulation model of the mechanical load is written and compared to manufacturer supplied data. The load model is then combined with a comprehensive electronic drive and motor simulation using an electromagnetic transient simulation program (PSCAD). A prototype of the vehicle is constructed by selecting the main components, an electric traction motor, batteries and a custom motor drive, using the simulation results. The results of both the simulation and prototypes are compared and evaluated. / February 2009
27

Sleepsafe

Nilsson, Tobias, Johlin, Jeanette January 2007 (has links)
Syftet med arbetet är att lösa problemet med det befintliga låset till spjälsängen Sesam, en säng anpassad för funktionshindrade småbarnsföräldrar som genom att ha grindar på fram-sidan gör det lätt även för en rullstolsburen eller muskelsvag person att komma åt. Problemet är dels att grindarna behöver lyftas upp för att öppnas, ett moment som kan vara svårt för en person med nedsatt muskelfunktion. Det andra problemet är att överliggaren är för lätt att öppna inifrån och har dålig hållfasthet. Målet är att i samarbete med Mayday Aid AB ta fram ett lås som löser problemet. Metod: BAD, MAD, CAD, Benchmarking, Past- och real time studies. Bakgrund: Antalet föräldrar med funktionshinder ökar snabbt.2 Detta kan tyda på en attitydförändring med en ökad social integration och en naturlig förväntan att leva ett fullvärdigt liv. I deras syn på sig själva har de försökt avlägsna sig från rollen som vårdtagare och i stället ser de sig som självständiga individer med i stort sett samma behov, rättigheter och skyldigheter som alla andra. En vid sjukdomsbild har genomförts för att på bästa sätt tillmötesgå målgruppen vid utformningen av produkten. Resultat: Låset ”Sleepsafe” tillverkat av björkplywood som bevisligen minskar den kraft som behövs för att öppna grindarna. Mätningarna visade att det endast krävs 6.52 N med nya låsets konstruktion att jämföra med 19.99 N för den ursprungliga låskonstruktionen. Diskussion: Vi strävade efter att integrera hela låsningsmekanismen i en produkt för att slippa utföra flera moment vid öppnandet, men för att göra låset mer barnsäkert så monterades ett extra lås nedtill som då blir svårt för barnen att nå. Med nya gångjärn slipper man numera att lyfta hela grinden. Ett fantastiskt tillfälle gavs till att testa låset på de riktiga användarna på handikapp-mässan ”Leva och fungera” i Göteborg. Produkten justerades något efteråt. Med låsets nya konstruktion har problemen eliminerats och underlättar för användaren.
28

All-optical wavelength converter by field-driven quantum well device integrated with vertical waveguide directional coupler

Wu, Tsu-Hsiu 19 May 2011 (has links)
In present dissertation, field-driven quantum well (QW) device is proposed to obtain high-speed and high-efficiency all-optical wavelength converter (AOWC). A new type QW material, InGaAsP/InGaAlAs, is employed to improve not only quantum confined Stark effect, but also carrier life time during high electric field excitation. The bandwidth as well as efficiency can be enhanced. Thus, the slow gain recovery mechanism (~100ps) from conventional semiconductor optical amplifier (SOA)-based AOWC can be overcome. The dispersion- and efficient- limited fiber-based AOWC (~10ps) can also be avoided. -3dB frequency bandwidth exceeding 40GHz for both electrical-to-optical and photocurrent response has been observed from InGaAsP/InGaAlAs waveguide of AOWC, leading to above 40GHz bandwidth in optical-to-optical response. A 40 Gb/s measurement setup is finally used for testing eye-diagram and bit-error-ratio in order to verify the data transmission of AOWC. Low power penalty with 0.5 dB comparing with back-to-back system performance is measured, suggesting InGaAsP /InGaAlAs waveguide is applicable to all-optical processing. By exciting short optical pump pulse in such waveguide, as short as 6.4ps probe pulse is observed, breaking through 10ps order in conventional type of QW and thus indicating the plausibility of performing 100Gb/s all optical processing.
29

Taiwan Motorcycle Industry of Competitive Strategy - A Case Study of All Terrain Vehicle industry.

Wu, Chun-Chieh 26 June 2007 (has links)
Abstract The main core of this study is ATV industry in Taiwan to look for new development field. Basic on this point of view and Taiwan experience, this study analyses the ATV industry and market strategy for Taiwan manufacturer. From understanding the ATV industry further to analyses the currently development situation in Europe, American and Japanese market and the operating situation of main manufacturer assist with SOWT and Five Forces Framework analysis to help the manufacturer have more competition opportunity and offer the future development suggestion. The conclusion is as below: 1. The competition strategy of Taiwan ATV industry exist competition price and non-competition price strategy. The manufacturer must be in leading position of the new vehicles development in order to be the leader in this market. 2. As the market grow, the manufacturer must take difference strategy to win the customer confidence, and the quick changing of the out looking will be the key trend of the market. So to own the tooling development and production ability will make the products in great use. 3. The ATVs are mostly used on risky environments so the production liability are more important than others feature. In some countries, the end users form ATV club and in this way " brand reputation" is going to be important part. 4. The new manufacturer of ATV must take price strategy to win one place in the market. 5. The completive price is a short - term strategy, only the products difference can make the profit in long - term. 6. The future completion of Taiwan ATV industry decides on new technology and brand value increasing, not on price. Keyword: ATV, competition strategy , All Terrain Vehicle
30

Design of Steering Mechanisms of All-Terrain Vehicles

Chang, Ming-Chu 19 June 2001 (has links)
All-Terrain Vehicles, usually called ATVs, are a popular product in the leisure sport market. The steering mechanisms is one of the important components of ATVs to obtain better maneuverability. The purpose of this work is to develop a systematic design procedure for the steering mechanisms of ATVs. First, the particularities and the requirements of ATVs are investigated to induce the basic characteristics. Second, to carry out the creative design of steering mechanisms by using the systematic procedure of creative mechanism design. Third, to deduce the analytic theory of angle displacement, torque and stability for the design of steering mechanisms. Then a computer aided analysis program are written. Finally, to establish the quantitative design specification of the steering mechanisms of ATVs. Then the dimension synthesis and the steering mechanism to integrate with body of ATVs are illustrated with an example.

Page generated in 0.0562 seconds