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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.
261

Compact Electromagnetic Band-Gap Structures (EBG) and Its Applications in Antenna Systems

Zeng, Jingkun January 2013 (has links)
This dissertation is focused on design of compact electromagnetic magnetic band-gap structures (EBG). Several popular compact techniques are introduced and analyzed with equivalent surface impedance model. A novel compact EBG structure is investigated. Compared to the conventional uniplanar compact photonic band gap (UC-PBG) structure, a size reduction of 64.7% is achieved. A distinctive band gap is observed at 2.45 GHz with around 100 MHz bandwidth and zero reflection phase. Antenna applications of this novel EBG structure, including EBG patch antenna and EBG antenna array, have been presented. Simulation results further verify its characteristic of suppressing surface waves. For the EBG patch antenna, a more focused radiation pattern is obtained compared to a normal patch antenna. For an antenna array, the presence of EBG structure reduces the mutual coupling between the two radiating elements by 6 dB.
262

The effect of compact development on travel behavior, energy consumption and GHG emissions in Phoenix metropolitan area

Zhang, Wenwen 10 April 2013 (has links)
Suburban growth in the U.S. urban regions has been defined by large subdivisions of single-family detached units. This growth is made possible by the mobility supported by automobiles and an extensive highway network. These dispersed and highly automobile-dependent developments have generated a large body of work examining the socioeconomic and environmental impacts of suburban growth on cities. The particular debate that this study addresses is whether suburban residents are more energy intensive in their travel behavior than central city residents. If indeed suburban residents have needs that are not satisfied by the amenities around them, they may be traveling farther to access such services. However, if suburbs are becoming like cities with a wide range of services and amenities, travel might be contained and no different from the travel behavior of residents in central areas. This paper will compare the effects of long term suburban growth on travel behavior, energy consumption, and GHG emissions through a case study of neighborhoods in central Phoenix and the city of Gilbert, both in the Phoenix metropolitan region. Motorized travel patterns in these study areas will be generated using 2001 and 2009 National Household Travel Survey (NHTS) data by developing a four-step transportation demand model in TransCAD. Energy consumption and GHG emissions, including both Carbon Dioxide (CO₂) and Nitrous Oxide (N₂O) for each study area will be estimated based on the corresponding trip distribution results. The final normalized outcomes will not only be compared spatially between Phoenix and Gilbert within the same year, but also temporally between years 2001 and 2009 to determine how the differential land use changes in those places influenced travel. The results from this study reveal that suburban growth does have an impact on people's travel behaviors. As suburbs grew and diversified, the difference in travel behavior between people living in suburban and urban areas became smaller. In the case of shopping trips the average length of trips for suburban residents in 2009 was slightly shorter than that for central city residents. This convergence was substantially due to the faster growth in trip lengths for central city compared to suburban residents in the 8-year period. However, suburban residents continue to be more energy intensive in their travel behavior, as the effect of reduction in trip length is likely to be offset by the more intensive growth in trip frequency. Additionally, overall energy consumption has grown significantly in both study areas over the period of study.
263

Teoría de Krein-Milman en espacios vectoriales topológicos sobre cuerpos valuados

Pérez García, María Cristina 03 December 1982 (has links)
En esta memoria se incluyen diversas alternativas a una teoría de krein-milman no arquimediana las cuales vienen sugeridas bien por intentos anteriores de otros autores bien por conseguir una teoría unificada en los casos arquimediano o no o bien por lograr una teoría independiente del cuerpo valuado y que en condiciones de comparación dan lugar a resultados muy similares / This monography provides several alternatives to a non-Archimedan Krein-Milman Theory. They are suggested by some previous attempts to this subject carried out by other authors, as well as by the aim of getting an unified theory that works in the Archimede and in the non-Archimedean cases, in the sense that in the Archimedean context, this theory coincides with the well-known one existing in the classical literature
264

GMPLS-OBS interoperability and routing acalability in internet

Mendoça Pedroso, Pedro Miguel 16 December 2011 (has links)
The popularization of Internet has turned the telecom world upside down over the last two decades. Network operators, vendors and service providers are being challenged to adapt themselves to Internet requirements in a way to properly serve the huge number of demanding users (residential and business). The Internet (data-oriented network) is supported by an IP packet-switched architecture on top of a circuit-switched, optical-based architecture (voice-oriented network), which results in a complex and rather costly infrastructure to the transport of IP traffic (the dominant traffic nowadays). In such a way, a simple and IP-adapted network architecture is desired. From the transport network perspective, both Generalized Multi-Protocol Label Switching (GMPLS) and Optical Burst Switching (OBS) technologies are part of the set of solutions to progress towards an IP-over-WDM architecture, providing intelligence in the control and management of resources (i.e. GMPLS) as well as a good network resource access and usage (i.e. OBS). The GMPLS framework is the key enabler to orchestrate a unified optical network control and thus reduce network operational expenses (OPEX), while increasing operator's revenues. Simultaneously, the OBS technology is one of the well positioned switching technologies to realize the envisioned IP-over-WDM network architecture, leveraging on the statistical multiplexing of data plane resources to enable sub-wavelength in optical networks. Despite of the GMPLS principle of unified control, little effort has been put on extending it to incorporate the OBS technology and many open questions still remain. From the IP network perspective, the Internet is facing scalability issues as enormous quantities of service instances and devices must be managed. Nowadays, it is believed that the current Internet features and mechanisms cannot cope with the size and dynamics of the Future Internet. Compact Routing is one of the main breakthrough paradigms on the design of a routing system scalable with the Future Internet requirements. It intends to address the fundamental limits of current stretch-1 shortest-path routing in terms of RT scalability (aiming at sub-linear growth). Although "static" compact routing works fine, scaling logarithmically on the number of nodes even in scale-free graphs such as Internet, it does not handle dynamic graphs. Moreover, as multimedia content/services proliferate, the multicast is again under the spotlight as bandwidth efficiency and low RT sizes are desired. However, it makes the problem even worse as more routing entries should be maintained. In a nutshell, the main objective of this thesis in to contribute with fully detailed solutions dealing both with i) GMPLS-OBS control interoperability (Part I), fostering unified control over multiple switching domains and reduce redundancy in IP transport. The proposed solution overcomes every interoperability technology-specific issue as well as it offers (absolute) QoS guarantees overcoming OBS performance issues by making use of the GMPLS traffic-engineering (TE) features. Keys extensions to the GMPLS protocol standards are equally approached; and ii) new compact routing scheme for multicast scenarios, in order to overcome the Future Internet inter-domain routing system scalability problem (Part II). In such a way, the first known name-independent (i.e. topology unaware) compact multicast routing algorithm is proposed. On the other hand, the AnyTraffic Labeled concept is also introduced saving on forwarding entries by sharing a single forwarding entry to unicast and multicast traffic type. Exhaustive simulation campaigns are run in both cases in order to assess the reliability and feasible of the proposals.
265

Compact modeling of gate tunneling leakage current in advanced nanoscale soi mosfets

Darbandy, Ghader 10 December 2012 (has links)
En esta tesis se han desarrollado modelos compactos de corriente de fuga por túnel de puerta en SOI MOSFET (de simple y doble puerta) avanzados basados en una aproximación WKB de la probabilidad de túnel. Se han estudiado los materiales dieléctricos high-k más prometedores para los diferentes requisitos de nodos tecnológicos de acuerdo ala hoja de ruta ITRS de miniaturización de dispositivos electrónicos. Hemos presentado un modelo compacto de particionamiento de la corriente de fuga de puerta para un MOSFET nanométrico de doble puerta (DG MOSFET), utilizando modelos analíticos de la corriente de fuga por el túnel directo de puerta. Se desarrollaron también Los modelos analíticos dependientes de la temperatura de la corriente de túnel en la región de inversión y de la corriente túnel asistido por trampas en régimen subumbral. Finalmente, se desarrolló una técnica de extracción automática de parámetros de nuestro modelo compacto en DG MOSFET incluyendo efectos de canal corto. La corriente de la puerta por túnel directo y asistido por trampas modelada mediante los parámetros extraídos se verificó exitosamente mediante comparación con medidas experimentales.
266

24 hour living room : Konstruktion av en kombinationsmöbel / 24 hour living room : Design of combination furniture

Lindgren, Markus January 2007 (has links)
Detta examensarbete är genomfört i samarbete med produktutvecklingsavdelningen på IKEA i Älmhult. Ingvar Kamprad startade IKEA år 1943 som en postorderfirma. Idag är företaget ett av världens största möbelföretag med 253 varuhus i 35 länder och med en omsättning på 161 miljarder kronor. Compact living är ett område på frammarsch inom inredningsvärlden. IKEA strävar efter att kunna erbjuda marknadskraftig heminredning inom alla områden. 24 hour Living room och dess delprojekt är en utgångspunkt för framtida idéer inom området. 24 hour Livingroom är ett projekt där en urban lägenhet på cirka 40m2 skall möbleras för ett compact living. Nyframtagna möbler och prototyper skall förenkla vardagen för en familj på två vuxna och två barn. Examensarbetet som en del av 24 hour, går ut på att utveckla en möbel som kombinerar sovplats och arbetsplats, men samtidigt vara kombinerbar med förvaringsserien Bestå från nuvarande sortiment. Syftet med prototypen är att minimera oanvänd yta - att göra små ytor större. En utförlig funktionsanalys där möbelns egenskaper och begränsningar redovisas, har tillsammans med IKEAs standarder utgjort parametrar för möbelns förutsättningar i materialtjocklekar, viktkrav och utseende. Då ergonomi står i fokus i dagens och framtidens arbetsmiljöer är möbeln konstruerad för att förenkla vardagen och minimera kroppsbelastningen. I rapporten kommer möbelindustrins vanligaste produktionsmaterial och ytbehandlingsmetoder att beskrivas. Här kommer även områden såsom IKEAsortimentets madrassalternativ och väggfästen att redogöras. Fokus i arbetet har legat på konstruerandet av en användbar prototyp. För att användaren skall slippa plocka bort och ställa fram dator med mera, varje gång funktion växlas, har skrivbordet utvecklats så det alltid är i ett horisontellt läge. Madrass och sängkläder lider av samma problematik, detta löses genom att madrassen står i en 90 graders vinkel under tiden kombinationsmöbeln används som arbetsplats. För att få en kortare utvecklingstid och en förenklad produktion har målet varit att använda IKEA components redan existerande beslag och förstärkningar. Ritningar för möbeln är gjorda efter IKEAstandard i 3d programmet SolidWorks och prototypen är skapad av IKEAs modellverkstad i Älmhult.
267

Flying Carpets from East to West : An Examination on Corporate Social Responsibility within the Indian Carpet Industry

Johansson, Emma January 2012 (has links)
Corporate social responsibility is a concept widely discussed by businesses and has come to describe the relationship between business and society. For some it means the idea o legal responsibility, an ethical behaviour and some equate it with charitable contribution. The World Business Council for Sustainable Development (Hopkins, 2007: 25) defines CSR as follows:   "Corporate Social Responsibility is the continuing commitment by business to contribute to economic development while improving the quality of life of the workforce and their families as well as of the community and society at large."   The relationship is increasingly striving to counteract a variety of problems that are associated with the contemporary globalization, such as violation of human and labour rights along with environmental challenges and is well-mentioned both by academics and businessmen. Within the Indian carpet industry, child labour has become a hot topic due to major scandals on the issues in the 1990s. Though, the meaning of corporate social responsibility is less common. The purpose of this study is to examine the Indian carpet industry’s awareness and use of the international agenda of corporate social responsibility, hence how the carpet export houses approach the responsibility. Also, the purpose is to examine how the carpet weavers are affected by the policies and actions of the export houses.   A field study with an ethnographical approach has been conducted through the use of interviews and observations in the district of Bhadohi, state of Uttar Pradesh in India. The interviewees consisted of workers working with the finishing processes of carpets at two export houses’ factories as well as carpet weavers at the looms in the villages. The findings from the interviews were analyzed through the use of parts of the Sustainable Livelihood Framework and with this approach the weavers’ access to assets is analyzed in relation to the export houses’ applying of the international agenda of CSR, more precise in this study, the UN Global Compact’s principles of CSR. The main findings from this study show that the CSR principles of the UN Global Compact were followed to different extents by the export houses since they are prioritizing some principles before others. The distribution of responsibilities differs depending on the management of the export house, mainly because of how the demands from the buyers and consumers look like. Also, the prioritizing of the export houses has become to affect the weavers’ socio-economic situation and for some the access to assets has increased. Furthermore, the study reveal that corporate social responsibility to a large extent is directed and influenced by the buyers’ and consumers’ (mainly stationed abroad in Western countries) demand. Thereby, through the complex system of sub-contracting, carpet weavers are affected differently since CSR is interpreted and used in various ways that are considered as most “suitable” to the export house.
268

Two Coalitional Models for Network Formation and Matching Games

Branzei, Simina January 2011 (has links)
This thesis comprises of two separate game theoretic models that fall under the general umbrella of network formation games. The first is a coalitional model of interaction in social networks that is based on the idea of social distance, in which players seek interactions with similar others. Our model captures some of the phenomena observed on such networks, such as homophily driven interactions and the formation of small worlds for groups of players. Using social distance games, we analyze the interactions between players on the network, study the properties of efficient and stable networks, relate them to the underlying graphical structure of the game, and give an approximation algorithm for finding optimal social welfare. We then show that efficient networks are not necessarily stable, and stable networks do not necessarily maximise welfare. We use the stability gap to investigate the welfare of stable coalition structures, and propose two new solution concepts with improved welfare guarantees. The second model is a compact formulation of matchings with externalities. Our formulation achieves tractability of the representation at the expense of full expressivity. We formulate a template of solution concept that applies to games where externalities are involved, and instantiate it in the context of optimistic, neutral, and pessimistic reasoning. Then we investigate the complexity of the representation in the context of many-to-many and one-to-one matchings, and provide both computational hardness results and polynomial time algorithms where applicable.
269

Study on the surface modification of steel using the closed-type electrical discharge coating method and semi-sintered powder compact electrodes

Weng, Yu-Chi 03 February 2012 (has links)
This paper aims to create a hard modification layer of WC/Co/Fe on the surface of SKD11 work steel by using a new closed-type method of surface electrical discharge coating with the self-made tool electrode and CNC electrical discharge machine. The tool electrode is the composition of a semi-sintered powder compacted electrode and a cooper rod. The sintered powder compacted electrode making process is first to mix the WC/Co and Fe powders uniformly at 8:1, 4:1, 2:1 and 1:1 in weight ratio. Continually, it will form the cylinder of 8mm in diameter and 18mm in length approximately by compacting in different pressure (50~200 MPa) and sintering temperature (300~900 ¢J). The EDM condition is 1~12A discharge current, 25~500£gs pulse time, and 50% duty factor. The electrical discharge machining is proceeding in kerosene with tool electrode as cathode and workpiece as anode. The result is as following. It can be concluded that the best condition to fabricate the sintered powder compacted electrode is 1:1 in weight ratio between WC/Co and Fe powders; with 200Mpa compacting pressure and sintering temperature at 900¢J, which results in lowest electrical resistivity. Under such condition, the area covered ratio can reach 100% at best EDM condition, which is pulse time £non = 50 £gs, rest time £noff = 50 £gs, 8A in current and 1.5 min in machining time. The surface hardness of workpiece increases with machining time. The surface hardness dramatically increases to Hv1500 as machining time over 1.5 min. The hardness of modification layer equals to the WC/Co particle itself which brings to the best wear ability. Moreover, the hardness of under surface in between 48 £gm is much higher than it of the SKD11 work steel. The hardness in between 30 £gm can reach up to Hv1200 in particular. The hardness of surface modification layer increases linearly with machining time. However, the limit of surface modification layer is about 30 £gm, and the needed time is below 5 min.
270

Conduction Based Compact Thermal Modeling For Thermal Analysis Of Electronic Components

Ocak, Mustafa 01 June 2010 (has links) (PDF)
Conduction based compact thermal modeling of DC/DC converters, which are electronic components commonly used in military applications, are investigated. Three carefully designed numerical case studies are carried out at component, board and system levels using ICEPAK software. Experiments are conducted to gather temperature data that can be used to study compact thermal models (CTMs) with different levels of simplification. In the first (component level) problem a series of conduction based CTMs are generated and used to study the thermal behavior of a Thin-Shrink Small Outline Package (TSSOP) type DC/DC converter under free convection conditions. In the second (board level) case study, CTM alternatives are produced and investigated for module type DC/DC converter components using a printed circuit board (PCB) of an electro-optic system. In the last case study, performance of the CTM alternatives generated for the first case are assessed at the system level using them on a PCB placed inside a realistic avionic box. v Detailed comparison of accuracy of simulations obtained using CTMs with various levels of simplification is made based on experimentally obtained temperature data. Effects of grid size and quality, choice of turbulence modeling and space discretization schemes on numerical solutions are discussed in detail. It is seen that simulations provide results that are in agreement with measurements when appropriate CTMs are used. It is also showed that remarkable reductions in modeling and simulation times can be achieved by the use of CTMs, especially in system level analysis.

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