• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 48
  • 10
  • 6
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 89
  • 89
  • 45
  • 35
  • 27
  • 13
  • 12
  • 11
  • 10
  • 9
  • 7
  • 6
  • 6
  • 6
  • 6
  • 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.
81

[en] LEAN COMMUNICATION-CENTERED DESIGN: A LIGHTWEIGHT DESIGN PROCESS / [pt] LEAN COMMUNICATION-CENTERED DESIGN: UM PROCESSO LEVE DE DESIGN CENTRADO NA COMUNICAÇÃO

DANIEL VITOR COSTA FERREIRA 11 January 2017 (has links)
[pt] O Lean Communication-Centered Design (LeanCCD) é um processo de design de Interação Humano-Computador (IHC) centrado na comunicação, que consiste na realização de um workshop, detalhamento de metas de usuários, combinação de modelos de interação com esboços em papel simulados com usuários, apoiados por guias e quadros. A IHC é uma área que estuda o projeto e uso de tecnologia computacional, em especial a interação entre computadores e pessoas. Este estudo adaptou o Communication-Centered Design (CCD) e o eXtreme Communication-Centered Design (eXCeeD), outros processos de design centrados na comunicação fundamentados na Engenharia Semiótica (EngSem). A EngSem é uma teoria de IHC que define a interação como um processo comunicativo entre designers e usuários mediado por computadores. Abordagens e processos fundamentados nessa teoria buscam favorecer a reflexão através da adoção de modelos, questões e métodos que não gerem diretamente uma resposta ou solução para o problema, mas apoiem o designer na exploração do espaço e da natureza do problema, bem como das restrições sobre soluções candidatas. A avaliação do LeanCCD em um estudo de caso na indústria observou dificuldade na condução das atividades e na aplicação correta de algumas técnicas e conceitos. Porém, diferentemente do eXCeeD, percebemos o uso sistemático das questões que favoreciam a reflexão devido ao auxílio dos quadros e guias propostos. / [en] Lean Communication-Centered Design (LeanCCD) is a Human-Computer Interaction (HCI) design process, which consists of conducting a workshop, detailing user goals, combining interaction models with paper sketches, and testing them with users, supported by guides and templates. This study adapted the Communication-Centered Design (CCD) and the eXtreme Communication-Centered Design (eXCeeD), other communication-centered design processes grounded on Semiotic Engineering (SemEng). SemEng defines the interaction as a computer-mediated communication process between designers and users. Approaches and processes based on SemEng are not used to directly yield the answer to a problem, but to increase the problem-solver s understanding of the problem itself and the implication it brings about. Process evaluation in a case study, in the industry, proved itself difficult, both in carrying out LeanCCD activities and in the correct application of some techniques and concepts. However, unlike eXCeeD, we were able to observe a systematic use of questions that contributed to designers reflection, aided by the proposed templates and guides.
82

Mobility Management in Next Generation All-IP Based Wireless Systems

Xie, Jiang (Linda) 09 April 2004 (has links)
Next generation wireless systems have an IP-based infrastructure with the support of heterogeneous access technologies. One research challenge for next generation all-IP based wireless systems is to design intelligent mobility management techniques that take advantage of IP-based technologies to achieve global roaming between various access networks. To support global roaming, next generation wireless systems require the integration and interoperation of heterogeneous mobility management techniques. Mobility in a hierarchical structure or multilayered environment should be supported. The objective of this study is to develop new mobility management techniques for global roaming support in next generation all-IP based wireless systems. More specifically, new schemes for location management and paging in Mobile IP for network layer mobility support, and new schemes for location management and handoff management in heterogeneous overlay networks for link layer mobility support are proposed and evaluated. For network layer mobility support, a distributed and dynamic regional location management mechanism for Mobile IP is proposed. Under the proposed scheme, the signaling burden is evenly distributed and the regional network boundary is dynamically adjusted according to the up-to-date mobility and traffic load for each terminal. Next, a user independent paging scheme based on last-known location and mobility rate information for Mobile IP is proposed. The proposed scheme takes the aggregated behavior of all mobile users as the basis for paging. For link layer mobility support, an IP-based system architecture for the integration of heterogeneous mobility management techniques is proposed. Three location management schemes under this IP-based architecture are proposed. All the three schemes support user preference call delivery which is a very important feature of next generation wireless communications. A threshold-based enhancement method is also proposed to further improve the system performance. Finally, a hybrid resource allocation scheme for handoff management in wireless overlay networks is proposed. Under this scheme, the overall system resources can be optimally allocated when mobile users are covered by multiple overlay networks.
83

Efficient Wideband Digital Front-End Transceivers for Software Radio Systems

Abu-Al-Saud, Wajih Abdul-Elah 12 April 2004 (has links)
Software radios (SWR) have been proposed for wireless communication systems to enable them to operate according to incompatible wireless communication standards by implementing most analog functions in the digital section on software-reprogrammable hardware. However, this significantly increases the required computations for SWR functionality, mainly because of the digital front-end computationally intensive filtering functions, such as sample rate conversion (SRC), channelization, and equalization. For increasing the computational efficiency of SWR systems, two new SRC methods with better performance than conventional SRC methods are presented. In the first SRC method, we modify the conventional CIC filters to enable them to perform SRC on slightly oversampled signals efficiently. We also describe a SRC method with high efficiency for SRC by factors greater than unity at which SRC in SWR systems may be computationally demanding. This SRC method efficiently increases the sample rate of wideband signals, especially in SWR base station transmitters, by applying Lagrange interpolation for evaluating output samples hierarchically using a low-rate signal that is computed with low cost from the input signal. A new channelizer/synthesizer is also developed for extracting/combining frequency multiplexed channels in SWR transceivers. The efficiency of this channelizer/synthesizer, which uses modulated perfect reconstruction (PR) filter banks, is higher than polyphase filter banks (when applicable) for processing few channels, and significantly higher than discrete filter banks for processing any number of variable-bandwidth channels where polyphase filter banks are inapplicable. Because the available methods for designing modulated PR filter banks are inapplicable due to the required number of subchannels and stopband attenuation of the prototype filters, a new design method for these filter banks is introduced. This method is reliable and significantly faster than the existing methods. Modulated PR filter banks are also considered for implementing a frequency-domain block blind equalizer capable of equalizing SWR signals transmitted though channels with long impulse responses and severe intersymbol interference (ISI). This blind equalizer adapts by using separate sets of weights to correct for the magnitude and phase distortion of the channel. The adaptation of this blind equalizer is significantly more reliable and its computational requirements increase at a lower rate compared to conventional time-domain equalizers making it efficient for equalizing long channels that exhibit severe ISI.
84

Network Design and Routing in Peer-to-Peer and Mobile Ad Hoc Networks

Merugu, Shashidhar 19 July 2005 (has links)
Peer-to-peer networks and mobile ad hoc networks are emerging distributed networks that share several similarities. Fundamental among these similarities is the decentralized role of each participating node to route messages on behalf of other nodes, and thereby, collectively realizing communication between any pair of nodes. Messages are routed on a topology graph that is determined by the peer relationship between nodes. Although routing is fairly straightforward when the topology graph is static, dynamic variations in the peer relationship that often occur in peer-to-peer and mobile ad hoc networks present challenges to routing. In this thesis, we examine the interplay between routing messages and network topology design in two classes of these networks -- unstructured peer-to-peer networks and sparsely-connected mobile ad hoc networks. In unstructured peer-to-peer networks, we add structure to overlay topologies to support file sharing. Specifically, we investigate the advantages of designing overlay topologies with small-world properties to improve (a) search protocol performance and (b) network utilization. We show, using simulation, that "small-world-like" overlay topologies where every node has many close neighbors and few random neighbors exhibit high chances of locating files close to the source of file search query. This improvement in search protocol performance is achieved while decreasing the traffic load on the links in the underlying network. In the context of sparsely-connected mobile ad hoc networks where nodes provide connectivity via mobility, we present a protocol for routing in space and time where the message forwarding decision involves not only where to forward (space), but also when to forward (time). We introduce space-time routing tables and develop methods to compute these routing tables for those instances of ad hoc networks where node mobility is predictable over either a finite horizon or indefinitely due to periodicity in node motion. Furthermore, when the node mobility is unpredictable, we investigate several forwarding heuristics to address the scarcity in transmission opportunities in these sparsely-connected ad hoc networks. In particular, we present the advantages of fragmenting messages and augmenting them with erasure codes to improve the end-to-end message delivery performance.
85

Enhancing numerical modelling efficiency for electromagnetic simulation of physical layer components

Sasse, Hugh Granville January 2010 (has links)
The purpose of this thesis is to present solutions to overcome several key difficulties that limit the application of numerical modelling in communication cable design and analysis. In particular, specific limiting factors are that simulations are time consuming, and the process of comparison requires skill and is poorly defined and understood. When much of the process of design consists of optimisation of performance within a well defined domain, the use of artificial intelligence techniques may reduce or remove the need for human interaction in the design process. The automation of human processes allows round-the-clock operation at a faster throughput. Achieving a speedup would permit greater exploration of the possible designs, improving understanding of the domain. This thesis presents work that relates to three facets of the efficiency of numerical modelling: minimizing simulation execution time, controlling optimization processes and quantifying comparisons of results. These topics are of interest because simulation times for most problems of interest run into tens of hours. The design process for most systems being modelled may be considered an optimisation process in so far as the design is improved based upon a comparison of the test results with a specification. Development of software to automate this process permits the improvements to continue outside working hours, and produces decisions unaffected by the psychological state of a human operator. Improved performance of simulation tools would facilitate exploration of more variations on a design, which would improve understanding of the problem domain, promoting a virtuous circle of design. The minimization of execution time was achieved through the development of a Parallel TLM Solver which did not use specialized hardware or a dedicated network. Its design was novel because it was intended to operate on a network of heterogeneous machines in a manner which was fault tolerant, and included a means to reduce vulnerability of simulated data without encryption. Optimisation processes were controlled by genetic algorithms and particle swarm optimisation which were novel applications in communication cable design. The work extended the range of cable parameters, reducing conductor diameters for twisted pair cables, and reducing optical coverage of screens for a given shielding effectiveness. Work on the comparison of results introduced ―Colour maps‖ as a way of displaying three scalar variables over a two-dimensional surface, and comparisons were quantified by extending 1D Feature Selective Validation (FSV) to two dimensions, using an ellipse shaped filter, in such a way that it could be extended to higher dimensions. In so doing, some problems with FSV were detected, and suggestions for overcoming these presented: such as the special case of zero valued DC signals. A re-description of Feature Selective Validation, using Jacobians and tensors is proposed, in order to facilitate its implementation in higher dimensional spaces.
86

Power line communications for the electrical utility: physical layer design and channel modeling

Aquilué de Pedro, Ricardo 16 July 2008 (has links)
El món de les comunicacions per la xarxa elèctrica (CXE) pot ser dividit en tres grans tipus: CXE en baix voltatge (CXE-BV), en mig voltatge (CXE-MV) i en alt voltatge (CXE-AV). En aquests últims anys, les CXE-BV han atret una gran expectació, ja que les seves capacitats han fet d'aquesta tecnologia una bona opció com alternativa pel bucle local d'accés i pel desplegament de xarxes d'àrea local, focalitzades aquestes últimes en l'entorn domèstic. A més, les CXE-BV inclouen un conjunt d'aplicacions de baixa velocitat orientades a l'operador, com la lectura automàtica de comptadors (LAC), distribució de càrrega, facturació dinàmica, etc. Per altra banda, les CXE-MV i CXE-AV, històricament lligades a tasques de telecontrol i teleprotecció, s'estan començant a considerar com un canal de comunicacions eficient i fiable. El desenvolupament de sistemes digitals i els esforços d'estandardització estan fent d'aquests canals un medi atractiu per a que els operadors elèctrics ofereixin serveis de comunicacions, ja que no necessiten invertir en infraestructura perquè la xarxa elèctrica ja està desplegada.En aquesta Tesi s'introduiran i es comentaran les particularitats de les tres xarxes elèctriques, després, es mostraran al lector les solucions tecnològiques existents pels canals de BV basats en la norma Europea CENELEC així com pels canals d'AV, mostrant que els sistemes actuals de LAC ofereixen una diversitat freqüencial molt baixa i que els mòdems CXE-AV estan ancorats en estendards antiquats.Aquest treball es mou per les tres topologies de la xarxa, particularment, en aplicacions orientades a la banda CENELEC, en mesura i modelat de canal, i en mesura i disseny del nivell físic per sistemes CXE-BV, CXE-MV i CXE-AV respectivament. Els sistemes actuals que exploten la banda CENELEC ofereixen mecanismes d'explotació de la diversitat freqüencial del canal molt limitats o nuls, donant lloc a una baixa robustesa en front a interferències i soroll de fons acolorit. Aquest treball proposa un esquema de modulació multiportadora que, mantenint una complexitat baixa, ofereix unes altes prestacions permetent un bon nivell d'explotació de la selectivitat freqüencial. Per al que a CXE-MV respecta, aquesta Tesi desenvolupa un model de canal determinístic-estadístic pels anells urbans de distribució de potència i, finalment, en sistemes CXE-AV, aquest treball proposa, basat en mesures de canal i proves de camp, un nivell físic de banda ampla capaç de incrementar la velocitat de comunicació mentre manté una baixa densitat espectral de potència limitant així la interferència a altres sistemes.PARAULES CLAU: Power line communications (PLC), low voltage (LV), medium voltage (MV), high voltage (HV), automatic meter reading (AMR), orthogonal frequency division multiplexing (OFDM), multicarrier spread spectrum (MC-SS), communication system design, channel measurements, channel modeling, scattering parameters. / El mundo de las comunicaciones por la red eléctrica (CRE) puede ser dividido en tres grandes tipos: CRE en bajo voltaje (CRE-BV), en medio voltaje (CRE-MV) y en alto voltaje (CRE-AV). En estos últimos años, las CRE-BV han atraído una gran expectación, ya que sus capacidades han hecho de esta tecnología una buena opción como alternativa para el bucle local de acceso y para el despliegue de redes de área local, focalizadas estas últimas en el entorno doméstico. Además, las CRE-BV incluyen un conjunto de aplicaciones de baja velocidad orientadas al operador como la lectura automática de contadores (LAC), distribución de carga, facturación dinámica, etc. Por otro lado, las CRE-MV y CRE-AV, históricamente ligadas a tareas de telecontrol y teleprotección, se están empezando a considerar como un canal de comunicaciones eficiente y fiable. El desarrollo de sistemas digitales y los esfuerzos de estandarización están haciendo de estos canales un medio atractivo para que los operadores eléctricos ofrezcan servicios de comunicaciones, ya que no necesitan invertir en infraestructura porque la red eléctrica ya está desplegada.En esta Tesis se introducirán y se comentarán las particularidades de las tres redes eléctricas, luego, se mostrarán al lector las soluciones tecnológicas existentes para los canales de BV basados en la norma Europea CENELEC así como para los canales de AV, mostrando que los sistemas actuales de LAC ofrecen una diversidad frecuencial muy baja y que los módems CRE-AV están anclados en estándares anticuados.Este trabajo se mueve por las tres topologías de red, particularmente, en aplicaciones orientadas a la banda CENELEC, en medida y modelado de canal, y en medida y diseño del nivel físico para sistemas CRE-BV, CRE-MV y CRE-AV respectivamente. Los sistemas actuales que explotan la banda CENELEC ofrecen mecanismos de explotación de la diversidad frecuencial del canal muy limitados o nulos, dando lugar a una escasa robustez frente a interferencias y ruido de fondo coloreado. Este trabajo propone un esquema de modulación multiportadora que, manteniendo una complejidad baja, ofrece unas altas prestaciones permitiendo un buen nivel de explotación de la selectividad frecuencial. Por lo que a CRE-MV respecta, esta Tesis desarrolla un modelo de canal determinístico-estadístico para los anillos urbanos de distribución de potencia y, finalmente, en sistemas de CRE-AV, este trabajo propone, basado en medidas de canal y pruebas de campo, un nivel físico de banda ancha capaz de incrementar la velocidad de comunicación mientras mantiene una baja densidad espectral de potencia limitando así la interferencia a otros sistemas.PALABRAS CLAVE: Power line communications (PLC), low voltage (LV), medium voltage (MV), high voltage (HV), automatic meter reading (AMR), orthogonal frequency division multiplexing (OFDM), multicarrier spread spectrum (MC-SS), communication system design, channel measurements, channel modeling, scattering parameters. / The world of Power line communications (PLC) can be divided into three main types: low voltage PLC (LV-PLC), medium voltage PLC (MV-PLC) and high voltage PLC (HV-PLC). These last years, LV-PLC has attracted a great expectation since its wideband capabilities has made this technology a suitable choice for last-mile access and in-home communications. Moreover, LV-PLC also includes a utility oriented low frequency and low speed applications, such as automatic meter reading (AMR), load distribution, dynamic billing and so on. On the other hand, MV-PLC and HV-PLC, historically oriented to teleprotection and telecontrol tasks, are being considered as a reliable communication channel. The development of digital equipment and the standardization efforts are making those channels an attractive medium for electrical utilities telecommunications services, since the network, as well as in LV-PLC, is already deployed. In this PhD dissertation, the three different PLC topologies are reviewed and the different communications techniques in such channels exposed. Then, a deep technological review of existing AMR solutions for the European CENELEC band, as well as HV-PLC systems is given, showing that existing AMR systems deliver low frequency diversity and HV-PLC systems are anchored in old fashioned standards.This work walks around the three topologies, specifically, CENELEC band utility oriented applications, channel measurement and modeling and channel measurement and physical layer design, regarding LV-PLC, MV-PLC and HV-PLC respectively. Existing CENELEC compliant systems deliver low or none frequency diversity mechanisms, yielding in a low robustness against colored noise and interference. This work propose a multicarrier based physical layer approach that, while keeping the complexity low, delivers high performance allowing a great level of frequency diversity. Focusing on MV-PLC, a hybrid deterministic-statistical channel model for urban underground rings is developed and, finally, in HV-PLC systems, this work proposes, based on measurements and field tests, a wideband physical layer in order to increase data rate while keeping low both the power spectral density and possible interference to other systems.KEYWORDS: Power line communications (PLC), low voltage (LV), medium voltage (MV), high voltage (HV), automatic meter reading (AMR), orthogonal frequency division multiplexing (OFDM), multicarrier spread spectrum (MC-SS), communication system design, channel measurements, channel modeling, scattering parameters.
87

En informationsfilm för Kils slakteri : ”Det är skillnad på kött och kött” / An informercial for Kils slakteri : ”There´s a difference between meat and meat"

Hjellström, Martin, Paulsson, Richard January 2012 (has links)
Kils slakteri är ett slakteri med stora anor i Värmland. De har sedan nystarten 2010 sakta men säkert vuxit sig större och levererar köttprodukter till olika butiker och inrättningar, men även till gemene man via deras egna charkuteri. Företaget har starka värderingar och arbetar för att skapa en lokal profil där de strävar efter en spårbarhet genom hela kedjan, från uppfödning till konsument vilket skiljer dem från de stora konkurrenterna.   Vi har fått i uppdrag av Kils slakteri att skapa en informationsfilm som ska uppfylla deras önskemål som innebär att öka medvetenheten hos konsumenterna, och att marknadsföra företagets värderingar och budskap till målgruppen på ett så tilltalande sätt som möjligt. Slutprodukten skall ligga uppe på Kils slakteris hemsida och kommer att vara ca 6 minuter lång.   Vi har gjort en kvantitativ enkätundersökning med 100 respondenter ur vår kunds egendefinerade målgrupp. Syftet med enkäten var inte att ta reda på målgrupp, utan snarare att ta reda på vad den existerande målgruppen trodde sig kunna om köttproduktion och konsumtion, samt vad de hade för åsikter och attityder gentemot köttindustrin. Detta gjordes för att vi skulle se vilka punkter som var viktigast att framhäva extra i infomationsfilmen.   Informationsfilmen är uppdelad i fyra olika scener som är sammankopplade i kronologisk ordning. Varje scen berör en av de fyra viktigaste huvudfrågorna för vår kund som är: Djuruppfödning, kötthantering, försäljning/kundkontakt och till sist tillagning av kött. Man får som betraktare följa med genom hela processen, som berättas med hjälp av en kvinnlig berättarröst. Denna röst har även en roll i att knyta ihop de olika scenerna i filmen. Två personer från slakteriet finns även med i filmen där de berättar närmare i detalj om de olika momenten. Den första scenen är på bondgården, den andra i styckeriet, den tredje i butiken och den fjärde och sista utspelar sig i en trädgård där tillagningen sker. / Kils slakteri is a slaughterhouse with great traditions in Värmland. They have grown slow and steady since the reopening in 2010 and they deliver meat products to an array of different supermarkets and institutions, as well as to regular households through their own charcuterie. The company possesses strong values and works towards maintaining a local profile, in which they strive to create transparency through the whole process from breeding of the animals to the finished product for the consumer, which differ from the competitors in the business.   We have been given the task to create an infomercial that will meet Kils slakteris wishes with the film, which is to increase the consumer’s awareness, promote the companies values and reach out with their message to their audiences in the most appealing way possible. The end product will be displayed on their homepage and will be approximately 6 minutes long.   We made a survey with 100 respondents from our clients target audience. The purpose with the survey was not to estimate which people who are a part of the target audience, but to gain knowledge about what the target audience thought they knew about meat production and consumption, as well as to get an insight to what attitudes they had towards the meat industry. We used the answers from the survey as an indicator to which factors that needed most attention in the film.   The infomercial is divided in to four different scenes that are linked together in a chronological order. Each scene concerns one of four main topics which are: breeding, tenderization of meat, sales/costumer contact and last the cooking of meat. As a viewer you get to tag along a journey through the whole process, which is narrated by a female voice who also fills the purpose of binding the scenes together. Two representatives from the slaughterhouse is also present in the film to act as themselves as they talk about the main topics in detail. The first scene takes place at the farm, the second in the slaughter house, the third in the charcuterie and the fourth and last is a cooking scene in a backyard.
88

Projekt firemního designu a jeho příklad ve firmě Filamos s.r.o. / Project of the corporate design and its example of the company Filamos s.r.o.

Hartl, Jan January 2008 (has links)
This thesis deals with company design. The goal is to explain all relevant aspects, especially from company design project point of view. Practical case study of realization of company design project in company Filamos s.r.o. is a part of this thesis. First part explains the term company design, discusses its introduction in a company, administration and its changes. It deals with this term also in context of company identity or image, especially its line up to information strategy. Second part deals with preparation and realization of company design project in company Filamos s.r.o. while practical part deals above all with methodology of this project. The output of the project, "Graphical manual" of the company Filamos s.r.o., is attached.
89

A Study of International Space Station Ground/Crew Communication Methods with Applications to Human Moon and Mars Missions

Esper, Jennifer Eileen 05 May 2007 (has links)
The International Space Station utilizes many different forms of written and verbal communication between the flight crews and ground control personnel. This study analyzes the historical use of three regular communication methods, Daily Planning Conferences, Weekly Planning Conferences and written Daily Summaries, as well as specific, science and internal maintenance events for characteristics and perceived effectiveness across eight expeditions (4 ? 11). The results are recommendations for the continued use of, or substitution for, these methods for future long-duration human space missions, specifically to the Moon and to Mars. General conclusions are that most of the conference content could have been relayed through written/electronic methods, and that the Daily Summaries are considered succinct and effective as a communication cornerstone. Conclusions formed from the study of individual events involved the importance of well-written crew procedures, the effective stowage and retrieval of necessary materials and the selection of well-defined science experiments.

Page generated in 0.1485 seconds