250 research outputs found

    WEST: A Web Browser for Small Terminals

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    We describe WEST, a WEb browser for Small Terminals, that aims to solve some of the problems associated with accessing web pages on hand-held devices. Through a novel combination of text reduction and focus+context visualization, users can access web pages from a very limited display environment, since the system will provide an overview of the contents of a web page even when it is too large to be displayed in its entirety. To make maximum use of the limited resources available on a typical hand-held terminal, much of the most demanding work is done by a proxy server, allowing the terminal to concentrate on the task of providing responsive user interaction. The system makes use of some interaction concepts reminiscent of those defined in the Wireless Application Protocol (WAP), making it possible to utilize the techniques described here for WAP-compliant devices and services that may become available in the near future

    Modélisation et distribution adaptatives de grandes scènes naturelles

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    Cette thèse traite de la modélisation et la diffusion de grandes scènes 3D naturelles. Nous visons à fournir des techniques pour permettre à des utilisateurs de naviguer à distance dans une scène 3D naturelle, tout en assurant la cohérence botanique et l'interactivité. Tout d'abord, nous fournissons une technique de compression multi-résolution, fondée sur la normalisation, l'instanciation, la décorrélation, et sur le codage entropique des informations géometriques pour des modèles de plantes. Ensuite, nous étudions la transmission efficace de ces objets 3D. L'algorithme de paquétisation proposé fonctionne pour la plupart des représentations multi-résolution d'objet 3D. Nous validons les techniques de paquétisation par des expériences sur un WAN (Wide Area Network), avec et sans contrôle de congestion (Datagram Congestion Control Protocol). Enfin, nous abordons les questions du streaming au niveau de la scène. Nous optimisons le traitement des requêtes du côté serveur en fournissant une structure de données adaptée et nous préparons le terrain pour nos travaux futurs sur l'évolutivité et le déploiement de systèmes distribués de streaming 3D. ABSTRACT : This thesis deals with the modeling and the interactive streaming of large natural 3D scenes. We aim at providing techniques to allow the remote walkthrough of users in a natural 3D scene ensuring botanical coherency and interactivity.First, we provide a compact and progressive representation for botanically realistic plant models. The topological structure and the geometry of the plants are represented by generalized cylinders. We provide a multi-resolution compression scheme, based on standardization and instantiation, on difference-based decorrelation, and on entropy coding. Then, we study efficient transmission of these 3D objects. The proposed packetization scheme works for any multi-resolution 3D representation. We validate our packetization schemes with extensive experiments over a WAN (Wide Area Network), with and without congestion control (Datagram Congestion Control Protocol). Finally, we address issues on streaming at the scene-level. We optimize the viewpoint culling requests on server-side by providing an adapted datastructure and we prepare the ground for our further work on scalability and deployment of distributed 3D streaming systems

    Adaptive Modeling and Distribution of Large Natural Scenes

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    This thesis deals with the modeling and the interactive streaming of large natural 3D scenes. We aim at providing techniques to allow the remote walkthrough of users in a natural 3D scene ensuring botanical coherency and interactivity.First, we provide a compact and progressive representation for botanically realistic plant models. The topological structure and the geometry of the plants are represented by generalized cylinders. We provide a multi-resolution compression scheme, based on standardization and instantiation, on difference-based decorrelation, and on entropy coding. Then, we study efficient transmission of these 3D objects. The proposed packetization scheme works for any multi-resolution 3D representation. We validate our packetization schemes with extensive experiments over a WAN (Wide Area Network), with and without congestion control (Datagram Congestion Control Protocol). Finally, we address issues on streaming at the scene-level. We optimize the viewpoint culling requests on server-side by providing an adapted datastructure and we prepare the ground for our further work on scalability and deployment of distributed 3D streaming systems

    Audio processing on constrained devices

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    This thesis discusses the future of smart business applications on mobile phones and the integration of voice interface across several business applications. It proposes a framework that provides speech processing support for business applications on mobile phones. The framework uses Gaussian Mixture Models (GMM) for low-enrollment speaker recognition and limited vocabulary speech recognition. Algorithms are presented for pre-processing of audio signals into different categories and for start and end point detection. A method is proposed for speech processing that uses Mel Frequency Cepstral Coeffcients (MFCC) as primary feature for extraction. In addition, optimization schemes are developed to improve performance, and overcome constraints of a mobile phone. Experimental results are presented for some prototype applications that evaluate the performance of computationally expensive algorithms on constrained hardware. The thesis concludes by discussing the scope for improvement for the work done in this thesis and future directions in which this work could possibly be extended

    An energy efficient http adaptive streaming protocol design for mobile hand-held devices

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    Internet traffic generated from mobile devices has experienced a huge growth in the last few years. With the increasing popularity of streaming applications in mobile devices, video traffic generated from mobile devices is also increasing. One of the big challenges of streaming applications on mobile devices is the energy intensive behaviour of such applications. Energy management has always been a critical issue for mobile devices. A wireless network interface consumes a significant portion of the total system energy while active. During video streaming, the network interface is kept awake for a long period of time. This causes a large energy drain. There are several research works focused on reducing energy consumption during video streaming on mobile devices. HTTP adaptive streaming is gaining popularity as a method of video delivery because of its significant advantages in terms of both user-perceived quality and resource utilization. By using rate adaptation via changes in the requested video version, it adapts to varying network available capacity. There are several research work that aim to increase the performance of rate adaptation. None of the previous works have focused on reducing energy consumption during HTTP adaptive streaming. In this thesis, an energy efficient HTTP adaptive streaming protocol is designed. The new protocol uses an efficient buffer management approach and a three step bitrate selection mechanism. The proposed protocol is implemented by modifying the Adobe OSMF player version 1.6. Performance evaluation of the new protocol is carried out by running a number of experiments in both a lab environment and three real world environments. The experimental results show that the proposed protocol is able to achieve high amounts of sleep time (by more than an estimated 70% for WiFi and more than 35% for 3G/EDGE) and reduce energy consumption during data transfer. It can also reduce data wastage by 80% in case of playback interruption in the video playback

    A mobile tour guide app for sustainable tourism

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    Portugal has had a flourishing tourism sector for the past few years. In fact, Portugal’s tourism boom has made the industry one of the biggest contributors to the national economy and the largest employer. In the year 2019, Portugal had a total of 27 million tourists, surpassing once again the record established in the previous year. However, tourism also brings a series of unintended negative side effects, such as overcrowding. The Santa Maria Maior historic district in Lisbon is being particularly affected by this problem. The work undertaken in this dissertation is part of the Sustainable Tourism Crowding project, that aims to mitigate the overcrowding phenomenon in this district, by fostering a balanced distribution of visitors while promoting the visitation of sustainable points of interest. This dissertation focuses on developing a mobile app prototype targeted at tourists, through which these sustainable walking tour recommendations can be delivered. To validate the functional requirements of the prototype, more specifically the trip creation process, a series of unit tests, integration tests, and manual tests were developed. To evaluate the usability of the prototype, a user-centered approach was adopted during the design stage, in which two usability techniques were conducted with members of ISCTE’s research center ISTAR and partners from the Junta de Freguesia de Santa Maria Maior, that guided and validated the decisions made. The achieved prototype contains mechanisms for measuring tourists’ adherence to the recommended tours using the Dynamic Time Warping algorithm, which raises new research opportunities on tourists’ behaviour.O desenvolvimento próspero do setor turístico em Portugal nos últimos anos fez da indústria um dos maiores contribuintes para a economia nacional e o maior empregador do país. No ano de 2019, Portugal recebeu um total de 27 milhões de turistas, ultrapassando uma vez mais uma vez o recorde estabelecido no ano anterior. No entanto, o turismo traz também uma série de efeitos secundários negativos não intencionais, tais como overcrowding. A freguesia histórica de Santa Maria Maior em Lisboa está a ser particularmente afetada por este problema. O trabalho desenvolvido nesta dissertação faz parte do projeto de pesquisa Sustainable Tourism Crowding, que visa mitigar o fenómeno de overcrowding nesta freguesia, promovendo uma distribuição equilibrada dos visitantes e incentivando a visita de pontos de interesse sustentáveis. Esta dissertação foca-se no desenvolvimento de uma aplicação móvel protótipo destinada a turistas, através do qual recebem recomendações de visitas sustentáveis. Para validar os requisitos funcionais do protótipo, mais especificamente o processo de criação de visitas, foram desenvolvidos testes unitários, testes de integração, e testes manuais. Para avaliar a usabilidade do protótipo, foi adotada uma abordagem centrada no utilizador durante a fase de conceção, em que foram utilizadas duas técnicas de usabilidade em parceria com o ISTAR (centro de investigação do ISCTE) e com a Junta de Freguesia de Santa Maria Maior, cujos resultados guiaram e validaram as decisões tomadas. O protótipo desenvolvido contém mecanismos para medir a aderência dos turistas às recomendações sugeridas através do algoritmo Dynamic Time Warping, proporcionando novas oportunidades de pesquisa nesta área

    Development and evaluation of an intelligent handheld insulin dose advisor for patients with Type-1 diabetes

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    Diabetes mellitus is an increasingly common, chronic, incurable disease requiring careful monitoring and treatment so as to minimise the risk of serious long-term complications. It has been suggested that computers used by healthcare professionals and/or patients themselves may playa useful role in the diabetes care process. Seven key systems (AIDA, ADICOL, DIABETES, DIAS, IIumaLink, T-IDDM, POIRO) in the area of diabetes decision support, and their underlying techniques and approaches are summarised and compared. The development of the Patient-Oriented Insulin Regimen Optimiser (POIRO) for insulindependent (Type-I) diabetes, and its hybrid statistical and rule-based expert system is then taken forward. The re-implementation and updating of the system for the Palm OS family of modern Personal Digital Assistants (PDAs) is described. The evaluation of this new version in a seven week, randomised, open, cross-over clinical pilot study involving eight patients on short-acting plus long-acting insulin basalbolus regimens showed it to be easy-to-operate, reliable, not time consuming and well liked by patients. Following this, the characteristics and use of all currently available insulin formulations, and the corresponding insulin regimens are summarised. Algorithms to provide dose advice and decision support for patients taking the new rapid-acting, intermediate-acting and premixed insulin formulations are then developed. The user interface is improved and extended, amongst others through the development and use of a model describing individual user's meal time habits. Implementation-related issues encountered are discussed, and further work and future directions are identified and outlined. Motivated by the complex and safety-critical nature of systems such as POIRO, we also report on the use of the B abstract machine notation for the formal specification of the original POIRO system, and focusing on projects and published case studies. review the use of formal methods in the development of medical computer systems
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