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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.
311

[en] MOBILITY MANAGEMENT IN MOBILE CELLULAR COMMUNICATION NETWORS / [pt] GERÊNCIA DE MOBILIDADE EM REDES DE COMUNICAÇÃO MÓVEL CELULAR

PAULO ROBERTO DE LIRA GONDIM 08 June 2006 (has links)
[pt] Nos últimos anos, considerável debate tem ocorrido a respeito do tema gerência de mobilidade, face à necessidade de se fazer uso judicioso dos recursos de sinalização destinados para esse fim no âmbito de sistemas de comunicação móvel celular e de sistemas de comunicação pessoal (PCS). Dentre as estratégias de gerência de mobilidade, destaca-se a utilização do conceito de áreas de registro, amplamente empregadas a partir dos sistemas de 2a. geração, e permitindo reduzir o consumo de recursos devido a atualizações de localização. Outro conceito, o de áreas de paging, tem também se tornado bastante difundido, propiciando a economia de recursos gastos na procura de terminais móveis por ocasião de tentativas de completamento de chamadas para estes terminais. Este trabalho inicia-se com discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se no contexto do trabalho o modelo baseado em fluxo de fluídos e o modelo gravitacional. O problema de particionamento em áreas de localização (LAPP) é então tratado como um problema de particionamento de grafos, cuja elevada complexidade enseja a utilização de heurísticas capazes de propiciar a obtenção de soluções próximas da ótima. As heurísticas propostas destinam-se ao caso mais comum, em que áreas de localização são coincidentes com áreas de paging. Com base em metodologia utilizada para o LAPP, são propostas soluções para um outro problema, o ISHMP (Inter-Switch Handover Minimization Problem), cuja importância se prende não só ao elevado consumo de recursos mas também aos atrasos impostos pelo sistema aos usuários quando estes trocam de área de Mobile Switching Center. Assim, reduzir ao máximo a ocorrência de tais eventos é vantajoso tanto do ponto de vista do usuário quanto do sistema. As heurísticas propostas são essencialmente as mesmas para ambos os problemas, e mostram superioridade em termos de qualidade das soluções obtidas quando comparadas com propostas de outros autores, através de casos-padrão publicados na literatura e de testbed construído especialmente para a comparação. Apresenta-se ainda discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se o modelo baseado em fluxo de fluidos e o modelo gravitacional. O trabalho apresenta também estudo relativo às cargas de sinalização que ocorrem tnato na rede fixa (incluindo o tráfego de consultas e atualizações sobre as bases de dados) quanto na interface aérea. No apêndice, considerando o grafo que modela a rede celular, apresenta-se comprovação formal da conversão de pesos de nós e de arestas em novos pesos de arestas, permitindo o tratamento dos dois problemas de particionamento aqui abordados como problemas de edgepartitioning puros. / [en] In the past few years there hás been considerable debate over the question of mobility management in móbile cellular communication networks, due to the need of using the signaling system resources in a careful way. Among the strategies of location management, the utilization of registration areas has been difunded since the emergence of the second generation mobile communication systems, allowing to reduce the resource consumption due to location updates. Another concept, named paging areas, has also been extensively employed, allowing to save resources utilized localization of mobile terminals during the call setup for mobile stations. Initially, the Location Area Partitioning Problem (LAPP) is treated as a graph partitioning problem, largely recognized as NP-complete ([GARE 79], [LENG 90]) and leading to the utilization of heuristics, able to produce good sub-optimal solutions. The heuristics are proposed to solve the more usual case, where location areas are coincident with paging areas, and the frequency spectrum (radio resources). With the same methodology, another problem, named Inter- Switch Handover Minimization Problem (ISHMP), is adequately solved, being its relevance due to the elevated system resource consumption and to the severe delays imposed to users when their Mobile Switching Centers are changed. Thus, the diminution of the occurrence of such events id advantageous from both the user`s and the system`s points of view. The heuristics are eddentially the same for the two problems, and it is shown the superiority of the quality of the quality of the obtained solutions, when comparing them with other published results. The work also presents discussion about mobility models employed in the study of problems and techniques in the mobile communications area. Among such models, the fluid flow and the gravitational models are highlighted. A study concerning to the signaling load imposed to the fixed network (including queries and location update traffic over databases) and to the air interface is presented. Finally, starting from the average rate of mobile terminated calls and from a previously defined user impatience threshold, a new proposal for the definition of the optimal number of cells per paging area is presented.
312

[en] HANDWRITING RECOGNITION / [pt] RECONHECIMENTO DE CARACTERES MANUSCRITOS

MARCELO LUNA GONCALVES DE OLIVEIRA 26 July 2006 (has links)
[pt] Neste trabalho é proposta uma metodologia de processamento da imagem associada a uma rede neural de perceptrons multicamadas, que é capaz de segmentar e reconhecer caracteres manuscritos cursivos. Esta técnica é robusta quanto à mudança na escala e translação dos caracteres, ligeiras variações na forma do caracter e ruído provocado pro tremores na mão do escritor. Pode ainda tornar-se robusta quanto à rotação, dependendo da escolha dos Descritores de Fourier. O método aproveita a existência de características geométricas e topológicas ou padrões de linhas. Estes componentes são fundamentais na construção da letra. São descritos pré-processamentos, que produzem os esqueletos dos caracteres, tais como algoritmos de afinamento e alisamento heurístico, filtragem zonal para atenuação de retas horizontais e verticais, detecção de contornos, extração heurística de características e a computação dos Descritores de Fourier representantes dos padrões de linha formadores dos caracteres. Após sua extração, as características são combinadas à entrada da rede neural de modo que cada combinação é reconhecida como pertencente a um determinado caracter. Para completar, os resultados do reconhecimento são combinados de modo a eliminar a interseção de classes proveniente das combinações comuns a vários caracteres. Esta metodologia procura a segmentação e o reconhecimento da forma de caracteres manuscritos, sem utilizar qualquer análise de contexto, o que naturalmente pode aumentar sua eficiência. / [en] This work introduces an image processing methodology that, associated with a multi-level neural network of perceptrons, is able to isolate and recognize cursive handwritten characters. The character isolation technique makes use of fundamental geometric and topological aspectos of the characters. The work describe procedures to extract the characters skeletons, such as thinning and smoothing heuristic algorithms, zoned filtering to attenuate horizontal and vertical lines, contour detection, heuristic extraction of characteristics and the computation of Fourier Descriptors representing the line patterns, that compose the characters. After character extraction, its combined characteristics are presented to a neural network in order to allow recognition (identification). Finally, the results of the character identification are combined to avoid classification intersections, due to common aspects in a number of characters. The introduced methodology concerns only with the segmentation and form identification of the characters. It does not adress any context analysis.
313

Studying user experience: issues and problems of mobile services:– Case ADAMOS: User experience (im)possible to catch?

Arhippainen, L. (Leena) 28 April 2009 (has links)
Abstract User experience has become a popular term in research and industry. There has been a great attempt to study and design user experiences. This thesis gives a practical view to user experience studies and methods by reporting test settings and results of the ADAMOS case studies. The goal of the ADAMOS project was to investigate context- and action-sensitive services in terms of how users experience when the system can detect one’s location and actions, and then adjust according to this information. The aim of this thesis is to investigate problems and issues in studying user experiences of mobile services and to find out in which conditions the study of user experience is possible and meaningful. As a contribution this thesis provides practical information for conducting user experience studies and evaluating experiences. The first contribution is a framework (U2E-Frame), which I created and improved iteratively in each test case. The framework is method-independent and it can be used for planning and conducting tests. The second contribution of the thesis is the practical view to all methods that are created, applied, presented and evaluated in this thesis. Especially during this thesis work three novel methods (Mobile Feedback, 3E-Diary and SUE methodology) have been developed and evaluated. The evaluation of the research methods illustrates that the best practice to study user experience is to use several methods together. This enables deeper understanding of user experiences. As the third contribution of this thesis I introduce a proposal of ten user experience heuristics for design and evaluation of user experiences. The aim of these heuristics is to enable designers to understand what meaning user experience has in product design. Developers can use these heuristics for designing and evaluating user experience aspects in product design. This thesis presents the main challenges in user experience research: know what to study (comprehensive user experience), know how to study it (find appropriate methods) and know how to evaluate and design it (user experience heuristics). An answer to the research problem is that it is both possible and meaningful to study user experience when we know user experience targets, and features of the services we want to investigate, and we can use the most appropriate methods, ensure the participant’s commitment to the test and ensure analysing relationships between results collected with different methods.
314

Heuristiska algoritmer för schemaläggning i real-tidssystem med hänsyn till data beroenden / Heuristic minimization of data latency in offline scheduling of periodic real-time jobs

Abdulla, Ariyan, Andersson, Erik January 2018 (has links)
The schedule for the jobs in a real-time system can have a huge impact on how the system behave. Since real-time systems are common in safety applications it is important that the scheduling is done in a valid way. Furthermore, one can enhance the performance of the applications by minimizing data latency and jitter. A challenge is that jobs in real-time systems usually have complex constraints making it too time consuming to minimize data latency and jitter to optimality. The purpose of this report is to investigate the possibility of creating high quality schedules using heuristics, with the goal to keep the computational time under one minute. This will be done by comparing three different algorithms that will be used on real scheduling instances provided by the company Arcticus. The first algorithm is a greedy heuristic, the second one a local search and the third one is a metaheuristic, simulated annealing. The results indicate that the data latency can be reduced whilst keeping the computational time below one minute.
315

A Study of Factors of Creativity in Three Selected Fields of Study

Schutz, Edward E. 05 1900 (has links)
The purposes of the study are to identify factors of creativity which have been revealed in the fields of personality and cognitive theory, art education, and science, and to formulate a base for a theory of creativity.
316

A study of the iOS : An exploratory article on how large of a role the iOS has played in the success of the iPhone

Sandström, Kristian January 2011 (has links)
The iPhone has become a top selling smartphone since its launch in 2007 and has along with its iOS (Apple's mobile operating system) overtaken many popular and established mobile phone brands in the ratings. Some competitors have not been able to provide a competing smartphone while others have grouped together to withstand the Apple onslaught. There are probably quite a few reasons why the iPhone has become such a success, and one could likely write a report solely about those reasons. I will focus on one of them in this study, maybe one of the most important reasons: the iPhone came with a revolutionizing user interface. I have studied iOS applications and their user interface components along with related research in order to try and find out what exactly makes it so attractive and also to uncover any flaws I might stumble across along the way. In order to answer this, and to gain a better insight into the iOS, I have developed an iPhone application from scratch covering all of the basic functionality usually found in any other iPhone application. The results will show that most of it seems to relate with Apple enforcing very strict rules and guidelines, along with limitations placed on the developer and the process as a whole. This strict process ends with Apple evaluators performing a review of the finished product, using their guidelines as heuristics. These guidelines will be proven to have scientific credibility, and the controlled development process will be a key to defining the iOS success.
317

Résolution conjointe de problèmes d'ordonnancement et de routage / Integrated resolution of scheduling and routing problems

Vinot, Marina 26 October 2017 (has links)
Cette thèse porte sur la modélisation et la résolution de différents problèmes intégrés d'ordonnancement et de transport. Ces problèmes demandent, entre autre, une coordination entre des activités/opérations de production, qui se définissent par une date de début et une durée, et des opérations de transport, qui se définissent par une date de début, une date de fin et une quantité transportée. Pour résoudre ces problèmes, plusieurs méthodes d'optimisation de type métaheuristique sont proposées, afin d’obtenir des solutions de bonne qualité dans des temps raisonnables. Trois problèmes intégrés sont traités successivement : 1) un problème d’ordonnancement à une machine avec un problème de transport limité à un seul véhicule ; 2) un problème d’ordonnancement à une machine avec un problème de transport à plusieurs véhicules ; 3) un problème d’ordonnancement de type RCPSP avec une flotte hétérogène de véhicules, permettant le transport des ressources entre les activités. Le premier problème est un problème d'ordonnancement/transport de type PTSP (Production and Transportation Scheduling Problem - PTSP), limité à un seul véhicule, présenté en 2008 par Geismar et al.. Une méthode de résolution de type GRASP×ELS est proposée dans le chapitre 2, les résultats obtenus avec cette méthode sont comparés aux meilleurs résultats de la littérature. Cette méthode est étendue dans le chapitre 3, afin de traiter du problème de PTPSP, avec une flotte homogène de véhicules. La méthode proposée possède un champ d'application plus large que la méthode de Geimar et al., dédiée au PTSP avec un véhicule, mais permet de résoudre efficacement le cas à un véhicule. Le dernier problème traité concerne la résolution d'un RCPSP, dans lequel une flotte de véhicules assure le transport d'une ressource d'une activité à l'autre. L'objectif est d'offrir une approche tirant profit de décisions stratégiques (organiser des échanges – flot – entre des sites), pour déterminer un plan de transport. La difficulté principale consiste à utiliser le flot, pour déterminer les opérations de transport (création de lots), afin de résoudre le problème d'affectation des véhicules, pour finalement ordonnancer les opérations de transport. Sur ce problème, une méthode heuristique de transformation est présentée dans le chapitre 4, ainsi qu’une méthode exacte (basée sur un algorithme de plus court chemin à contraintes de ressources) dans le chapitre 5. / This dissertation focuses on modelling and resolution of integrated scheduling and routing problems. Efficient resolutions of these problems required a proper coordination of activities/production operation, defined by starting and finishing times, and of transport operations, fully defined by starting times, finishing times and quantities of resources transferred.The resolution of this problem is based on several metaheuristics, with the aim to obtain high quality solutions in acceptable computational time. Three problems are iteratively studied considering: 1) a single machine scheduling problem and a transportation problem with a single vehicle; 2) a single machine scheduling problem with a homogeneous fleet of vehicles for the transport; 3) a RCPSP where the flow transferred between activities is transported by a heterogeneous fleet of vehicles.The first problem addressed is the PTSP (Production and Transportation Scheduling Problem - PTSP) where the routing part is devoted to a single vehicle (Geismar et al., 2008). The chapter 2 focuses on a GRASP×ELS method benchmarked with the best published methods. This method is extended to the PTSP with multiple vehicles in the chapter 3, and the method shows its capacity to address a wide range of problem, since the PTSP with a single vehicle is a special case. The second problem deals with the RCPSP, where a heterogeneous fleet of vehicles is devoted to the transportation of resources, between activities. The objective consists in considering a flow (activity exchanges solved at a strategic level), to compute a transportation plan. The main difficulties consists in using the flow to compute transport batches. A heuristic-based approach is introduced in the chapter 4 and an exact method is provided in the chapter 5.
318

Decision making for IT service selection in Swedish SMEs : A study with focus on Swedish Small and Medium Sized Enterprises

Banuazizi Fard, Amir Hossein January 2014 (has links)
Problem There is a lack of knowledge about how Swedish SMEs make decisions on IT service selection. There is also lack of information about the attributes of IT service providers that are most important to Swedish SMEs. By discovering these attributes, IT service providers could focus on improving their services in those dimensions and become more attractive for Swedish small and medium enterprises. Purpose The purpose of this research is to investigate the decision making process over selection of IT services for small and medium sized enterprises (SMEs) in Sweden. Additionally, this research intends to discover the most important features (attributes) of an IT service provider in its selection. What are the steps involved in decision-making process? What decision-making methods can be used to help explain the process that goes on in the minds of the decision makers? What aspects influence their behaviour when decision makers prefer one service provider to another? IT service comprises of internet-based services such as web hosting, email services, online backup services and cloud apps or locally offered IT services such as IT helpdesk. The candidates who were interviewed were employees or entrepreneurs who work and live in Sweden. Method This research was conducted with an inductive approach using mono method for semi-structured interviews for primary data collection. Secondary data collection was multiple-source through literature reviews in order to learn about different attributes and current knowledge about this subject. The research method was qualitative with exploratory strategy in order to get insights into managers’ decision-making processes. Sampling was non-probability purposive method with sample size as saturation method. The focus was illustrative and method chosen as typical case. Conclusion The conclusions of this thesis illustrates that the important attributes (features) of IT services required by Swedish SMEs are the requirement that the service is being offered from Sweden, due to tax conformity laws and security matters. Moreover, SAT, WADD, FRQ and EBA are decision-making heuristics in use by the companies in selection of suitable IT services.
319

Evaluating usability aspects of a school photo mobile application

Royar Sazdar, Rocan January 2015 (has links)
Context. The market for mobile applications is expanding rapidly. Companies that have web-based applications are required to supply their costumerswith mobile applications to not fall behind and lose their costumers. Portinga web-based application to a mobile platform is not only about decreasing thesize of the web-pages’ content. To succeed in porting a web-based applicationto a mobile platform the usability of the application must remain the sameand possibly be improved, otherwise the consequence is that users becomefrustrated and leave the mobile application. Objectives. The objectives of this thesis is to investigate how to structureand display the features of a school photo web-based application to a mobileapplication, and keep the usability. Methods. A literature study has been done to find guidelines for designingmobile applications. Three mobile application prototypes have been devel-oped. The prototypes have been tested with usability tests in a laboratoryexperiment to find usability problems if such exists, and to identify the mostusable alternative. The usability tests have been done with the target groupof the mobile application. Results. The most usable prototype was identified. Also, a list of recommen-dations are compiled from the experiment (such as, provide help text underthe icons to clarify the content of the icon), and specific improvements thatcan be done to the most usable prototype is also compiled. Conclusions. As a conclusion, the used guidelines and usability heuristicssupported the design of the prototypes and helped to get user-friendly inter-faces. Prototype III obtained the best results in the usability tests. The resultsalso showed that the Prototype III can be further improved. It has also beenfound that related applications such as Instagram, can be helpful in order toget usable and user-friendly interfaces.
320

Affective Biases and Heuristics in Decision Making : Emotion regulation as a factor for decision making competence

Hagman, William January 2013 (has links)
Stanovich and West (2008) explored if measures of cognitive ability ignored some important aspects of thinking itself, namely that cognitive ability alone is not enough to generally prevent biased thinking. In this thesis a series of decision making (DM) tasks is tested to see if emotion regulation (ER) is a factor for the decision process and therefore should be a measured in decision making competence. A set of DM tasks was compiled involving both affective and cognitive dimensions. 400 participants completed an online web-survey. The results showed that ER ability was significantly associated with performance in various DM tasks that involved both heuristic and biased thinking. These findings suggest that ER can be a factor in decision making competence.

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