• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1561
  • 606
  • 372
  • 267
  • 174
  • 167
  • 121
  • 62
  • 62
  • 51
  • 50
  • 44
  • 22
  • 21
  • 18
  • Tagged with
  • 4146
  • 537
  • 439
  • 332
  • 285
  • 263
  • 261
  • 208
  • 204
  • 200
  • 174
  • 173
  • 168
  • 166
  • 166
  • 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.
101

Hållbarhet och miljö inom modebranschen

ANDERSSON, LINN, WILAND, FELICIA January 2013 (has links)
En rapport om hur Lindex arbetar med miljö- och hållbarhetsfrågor, samt hur de kommunicerar detta med sina kunder. / Program: Butikschef, textil och mode
102

Méthode d’optimisation du volume des bobines de mode commun pour la conception des filtres CEM / Optimization method of the volume of common mode inductors used in the design of EMI filters

Zaid, Bilel 30 November 2018 (has links)
Ce travail de thèse présente une méthode d'optimisation du volume de la bobine de mode commun qui est généralement l'élément le plus volumineux du filtre. Le manuscrit commence par faire l'état de l'art des perturbations électromagnétiques conduites en électronique de puissance et des moyens permettant leur réduction. Ensuite, un calcul analytique de l'inductance de mode commun minimale qui permet de respecter la norme CEM est présenté. Ce calcul prend en considération la perméabilité complexe du matériau magnétique et les impédances des chemins de propagation des perturbations de mode commun dans la chaîne. Une fois l'inductance minimale calculée, une méthode d'optimisation du volume de la bobine de mode commun monocouche qui tient compte de la saturation du matériau magnétique est présentée. L'application de la méthode proposée dans diverses situations a montré l'existence d'une meilleure inductance, pouvant être supérieure à sa valeur minimale, qui permet de réduire au mieux le volume de la bobine. Par ailleurs, des règles de dimensionnement en relation avec la fréquence de commutation du convertisseur et de son rapport cyclique sont définies. La dernière partie de cette étude est dédiée à la prise en compte des effets de la capacité parasite équivalente de la bobine dans la procédure de dimensionnement. D'abord, une méthode pour la détermination des permittivités relatives du noyau magnétique et pour l'estimation de la capacité parasite équivalente est proposée. Cette méthode, accompagnée d'un calcul de la capacité maximale autorisée, permet d'adapter la géométrie de la bobine afin de respecter la contrainte normative en HF tout en optimisant son volume. / This work presents an optimization method of the common mode inductor volume that is generally the biggest element of the filter. The manuscript starts by presenting the state of art of conducted electromagnetic interferences in power electronics and techniques that allow their reduction. Then, an analytical calculation method of the minimal inductance value that allows respecting the normative constraint is presented. This calculation method takes into account the complex permeability of the magnetic material and the impedances of the different propagation path of common mode disturbances in the conversion system. After that, an optimization method of the single layer inductor volume with considering the magnetic core saturation issues is proposed. The application of the proposed method in different situations has shown the existence of the best inductance value that can be higher than its minimal value while reducing the optimal inductor volume. In addition, some rules that can be used in the design process in relation to the switching frequency of the converter and its duty cycle are defined. In the last part of this study, the effect of the equivalent parasitic capacitance of the common mode inductor is discussed and introduced in the proposed optimization process. A determination method of magnetic core relative permittivities and of the equivalent parasitic capacitance is proposed. This method, in addition to the proposed analytical calculation of the maximal allowed parasitic capacitance, makes it possible to adapt common mode inductor geometry in order to respect the normative constraint in the high frequencies while optimizing its volume.
103

Applying loop-mirror and ring resonator on Non- Alumium epi-layer in the fabrication and design Fabry-Perot laser of wavelength in 1.55£gm

Lin, Chia-yi 30 July 2007 (has links)
The purpose of this thesis is to develop ring resonators with simple processes and integration. We used loop mirror as a reflector in the semiconductor lasers. In the material, a 1.55£gm symmetric quantum well InGaAsP epi-layer is used to fabricate the lasers. In device design, we designed four kinds of semiconductor lasers by using loop mirror and cleaved facet. The curvature radiuses are 160 and 260£gm that are presented to investigate bending loss and material loss. In the input/output we had an inclined 7 degree to avoid interference. We also designed another two semiconductor lasers by using ring resonator and cleaved facet. Applying the resonance characteristic of ring resonator can achieve wavelength selection and filtering. In fabrication process, we developed new etching technique. The ICP-RIE dry etching and wet etching method were used in the process. Fist we etched half of the total depth by ICP-RIE dry etching. And then the multi-step technique was used to approach the expecting depth. Beside, we had extra deep wet etching process in MMI. Finally, we used the etching solution HBr:HCl:H2O2:H2O =5:4:1:70 to smooth the sidewall and reduce the scattering loss. In device characteristic, we obtained differential quantum efficiency of 20£gW/mA for the 1000£gm straight waveguide laser. We can not observe laser characteristics for the loop mirror laser, partly because of the high loss in bending section.
104

The APOBEC3G Deamination Independent Mode of HIV Inhibition

2012 April 1900 (has links)
ABSTRACT APOBEC3G (Apo3G) is a host cell restriction factor of viruses that produce a singlestranded (ss) DNA replication intermediate (Sheehy et al., 2002; Suspene et al., 2004). Apo3G is studied primarily for its ability to restrict propagation of the retrovirus, HIV. In cell culture, Apo3G can only inhibit HIV if it lacks its virion infectivity factor (Vif). The host-pathogen interface between Apo3G and HIV has become a new target of study for the development of novel HIV therapeutics (Prochnow et al., 2009; Sheehy et al., 2003). Apo3G induces mutagenesis of the HIV proviral DNA (Mangeat et al., 2003; Zhang et al., 2003). Apo3G has the ability to induce transition mutations, i.e. cytosine to thymine, through deamination of cytosine to form uracil. Deamination activity induces numerous mutations that causes gene inactivation of the HIV provirus thus restricting the HIV lifecycle. Apo3G attenuates HIV virion infectivity in the absence of the virion infectivity factor (Vif) by inducing genome mutations through deamination of cytosine to uracil in HIV minus strand DNA. Independent from deaminase activity, Apo3G may also interfere with HIV reverse transcription by preventing full length cDNA from forming (Iwatani et al., 2007), nucleocapsid (NC) mediated strand annealing (Guo et al., 2007; Guo et al., 2009; Li et al., 2007), and RNaseH activity of the reverse transcriptase (Li et al., 2007). Whether Apo3G is able to restrict HIV by a deamination-independent mode remains controversial. In particular, the existence of the deamination independent mode was challenged since the Apo3G deamination null mutant E259Q was shown to have limited or no ability to inhibit HIV-1 replication (Schumacher et al., 2008). This research assesses the ability of Apo3G to inhibit reverse transcription of HIV genomic RNA. It is hypothesised that based on the ability of Apo3G to bind and oligomerize on single stranded nucleic acids (Chelico et al., 2008), and its high affinity for RNA (Chelico et al., 2010), that Apo3G can inhibit RT mediated primer extension as well as nucleocapsid mediated strand annealing. Additionally, it is hypothesized that Apo3G cannot inhibit RT RNAseH activity, as Apo3G has been shown to have a low affinity for DNA/RNA hybrids (Iwatani et al., 2006). We will test these hypotheses by using in vitro assays that mimic in vivo reverse transcription events. Here we have shown that Apo3G is able to decrease the efficiency with which HIV-1 reverse transcriptase synthesizes DNA from an RNA primer annealed to an RNA template. Apo3G had a minimal affect on primer initiation and primarily inhibits primer elongation. Using iii the monomeric mutant, F126A/W127A, we show that the deamination independent mode of inhibiting reverse transcriptase is impaired without oligomerization on template RNA. We also provide evidence that the Apo3G mutant E259Q should not be considered a deamination null proxy for native Apo3G since it exhibits decrease in RNA binding affinity compared to the native form. We did not find that Apo3G inhibited HIV NC-mediated strand annealing activity or RNaseH activity of HIV-1 reverse transcriptase. The data suggest a two-tiered mechanism for inhibition of reverse transcriptase-mediated DNA synthesis that is dependent upon 1) the ability of Apo3G to oligomerize on RNA substrates and 2) bind RNA with high affinity. Ascribing a mechanism to the deamination independent mode of HIV-1 restriction by Apo3G suggests that the enzyme may use this mechanism in vivo to delay completion of proviral DNA synthesis which, may negatively impact the HIV-1 lifecycle.
105

Mode en gråzon? : En studie av modebranschens position mellan konst och kommers

Persson, Maria, Knoester, Lina January 2008 (has links)
The purpose of our essay is to develop an understanding and an insight for the fashion industry. We want to examine what the creative industries can learn from the unique position that fashion hold in a field between commercialization and art. We used a theoretical ground to enlarge our understanding for the distinctive place that fashion holds. To gain further insight in the fashion industry we complete the theory with empirical facts. The empirical facts were collected through a qualitative method with deep-going interviews. The selection of informants was based on personal experience and insight of the relevant subject. Theory and empirical facts was a tool to gain understanding for the fashion industry. Our purpose was not to make generalization of the subject instead we focus on analyze and understand fashion in a field between commercialization and art.
106

Expansion of a small Swedish IT firm : A market and entry mode selection

Erlandsson, Erik, Hassan, Habane January 2012 (has links)
Internationalization within the information communication technology (ICT) sector has become more essential today and this has raised the international competition over customers. The Nordic markets growth and development in its ICT sector has brought new competition and has been the substance of change in business concerning, organizational changes, reduce transaction costs and rationalize and restrict supply chains. The purpose of this thesis is therefore to compare the Nordic ICT markets and the potential for small IT firm namely, Radar Group International AB. To be able to understand Radar Group’s potential in the Nordic IT markets this thesis is divided in to two aspects, market selection and entry mode selection. When we have evaluated the Nordic markets we made, based on our findings recommendations to Radar Group in what market to enter and how to enter that market. For comprehensive understanding of this study, we choose concentration of the theoretical framework committed to the subject, market selection and entry mode selection. Furthermore, we used qualitative method in collecting the empirical data consisting of raw data and in-depth interviews with three international IT firms based in Sweden about their market selection and entry mode selection. Our conclusion indicates that Radar Group should explore the Norwegian market as it offers greater customer potentials and stronger economic growth. While expanding to the Norwegian market, it is our opinion that Radar Group should use Joint venture as their entry mode. It is the most suitable mode for Radar Group in terms of financial aspect, the company’s business concept and previous experience.
107

Low-Complexity Mode Selection for Rate-Distortion Optimal Video Coding

Kim, Hyungjoon 06 April 2007 (has links)
The primary objective of this thesis is to provide a low-complexity rate-distortion optimal coding mode selection method in digital video encoding. To achieve optimal compression efficiency in the rate-distortion framework with low computational complexity, we first propose a rate-distortion model and then apply it to the coding mode selection problem. The computational complexity of the proposed method is very low compared to overall encoder complexity because the proposed method uses simple image properties such as variance that can be obtained easily. Also, the proposed method gives significant PSNR gains over the mode selection scheme used in TM5 for MPEG-2 because the rate-distortion model considers rate constraints of each mode as well as distortion. We extend the model-based mode selection approach to motion vector selection for further improvement of the coding efficiency. In addition to our theoretical work, we present practical solutions to real-time implementation of encoder modules including our proposed mode selection method on digital signal processors. First, we investigate the features provided by most of the recent digital signal processors, for example, hierarchical memory structure and efficient data transfer between on-chip and off-chip memory, and then present practical approaches for real-time implementation of a video encoder system with efficient use of the features.
108

Applying loop mirror and ring resonator in the fabrication and design of semiconductor laser

Huang, Tzu-chien 21 July 2005 (has links)
We present design and fabrication of ring cavity semiconductor lasers and single ring filter with simple fabrication processes. A 1.55-£gm symmetric quantum well InGaAlAs epi-layer wafer is used to fabricate the lasers. In device design, we apply loop mirror to obtain reflection instead of cleaved facet and take 1x2, and 2x2 Multi-Mode Interference (MMI) with different splitting ratio(50%:50%¡F15%:85%) as a coupler. Then we combine MMI couplers with ring cavities to control the output of specific wavelength. Therefore we can obtain filter and lasers with the property of wavelength selection. We also design two kinds of special waveguides to achieve low reflectivity. One is a tapered spiral waveguide tail. The other waveguide is expanded in a curve and then cut off at the Brewster¡¦s angle. In loop mirror, two curvature radius(260,160£gm) were introduced to study bending loss and material loss. In single ring filter, we design two kinds of resonator lengths(1479,1385£gm) and the corresponding Free Spectrum Range (FSR) are 63.4, 67.75GHz, respectively. In fabrication, owing to the unstable dry etch condition for InGaAlAs, we adopted multi-step etch technology. In the part of curved waveguide, we also use this method to make deep-etching to increase the difference of refractive index between waveguide and the outside part. Finally, we use the etch solution (HBr:HCl:H2O2:H2O=5:4:1:70) to smooth the sidewall of the waveguide, and to reduce scattering loss of the device.
109

Applying loop-mirror reflector in the fabrication and design of Fabry-Perot laser

Lai, Chun-ming 10 July 2006 (has links)
The purpose of this research is to present design and fabrication of resonant loop-mirror Fabry-Perot lasers. Single filter has simple fabrication processes and good potential for intergration. A 1.55-£gm symmetric quantum well InGaAlAs epi-layer wafer is used to fabricate the laser. In device design, we apply loop mirror to obtain reflection instead of cleaved facet and take 1x2, 2x2 Multi-Mode Interference (MMI) with different splitting ratio (50%:50%¡F15%:85%) as a coupler. Then we combine MMI couplers with ring cavities to reflect specific wavelength at particular position. Therefore we can obtain semiconductor laser with property of wavelength-selection filter. In this design of the mask, we add a mask of deep-etch around MMI in order to decrease the loss of higher mode inside MMI. In the part of devices design, we apply multi-step technology for wet etch to obtain necessary depth. Finally, we use the etch solution (HBr¡GHCl¡GH2O2¡GH2O¡×5¡G4¡G1¡G70) to smooth the sidewall of the waveguide, and to reduce scattering loss of the device. In the part of planarization, we can adhere dummy wafers to surround the main sample and extend the total area. If we can fill the gap flat, the problem of high edge by spinning will be solved. However, we were not able to fill the gap.
110

Frame-Based Fast Mode Decision on H.264

Li, Ming-Feng 01 July 2006 (has links)
The H.264/AVC video coding standard aims to enable significantly improved compression performance compared to all existing video coding standards. For achieve this purpose, a robust rate-distortion optimization (RDO) [4] technique is employed to select the best coding mode and reference frame for each macro-block. As a result, the complexity and computation load increase drastically. This paper presents a fast mode decision algorithm for H.264/AVC inter-prediction based on frame difference. There used signal to noise ratio (SNR) of 4*4 block information based on adjustable threshold to judge the mode type. Experimental results show that the fast inter-prediction mode decision scheme increases the speed of motion estimation significantly with negligible loss of peak signal-to-noise ratio.

Page generated in 0.0404 seconds