Improving the Performance of Wide Area Networks

Research in to the performance of wide area data networks is described in this thesis. A model of wide area network packet delays is developed and used to direct the research in to methods of improving performance. Wide area networks are slow and expensive compared to the computer systems that rely on them for communication. Typically data networks are packet switched in order to make efficient use of resources. This can lead to contention, and the mechanisms for resolving contention can bring about further delays when demand for resources is high. In this thesis, network users are viewed as interacting decision makers with conflicting interests, and Game Theory is used to analyse the effects users have on each other’s performance. It is asserted in this thesis that wide area network performance is an ethical issue as well as a technical one. Compression is examined as a technique for reducing network traffic load. While load reductions can reduce the time packets spend waiting in buffer queues experimental results show the compression process itself can present a bottleneck if CPU resources are limited. The other inhibiting factor with regard to wide area network performance is the time it takes for a signal to propagate through a transmission medium. Propagation delays are bounded by the speed of light and becomes significant as the distance between computer systems increases. Mirrors and Caches are methods of bringing data closer to the user, thereby reducing propagation delays and capping traffic loads on long haul communication facilities. The performance benefits of replicating data within a wide area network environment are studied in this thesis

Framework for media oriented transport systems

Dissertação de mestrado integrado em Engenharia Electrónica Industrial e ComputadoresThe natural evolution of embedded systems resulted in a faster execution of tasks, increased possibility for including additional features, allied to lower power consumption and benefiting from ever-growing rates of integration as far as silicon is concerned. The automotive industry is not an exception with regards to the integration of technology for a vast arrays of applications in systems which vary from entertainment of infotainment to systems related to vehicle safety and stability such as driver assists. The existence of diverse independent systems in modern cars, combined with the necessity of centralizing the user interface, simplifying the operation of the system and minimizing the user’s intervention, help to promote the comfort and reduce the likelihood of distractions taking place while driving. Modern communication oriented network standards, e.g. MOST or FlexRay, enable information compatibility when exchanged between systems communicating over different protocols. Moreover, the coexistence of packet, control and timesensitive information are ensured within timing requirements, providing a reliable QoS (Quality of Service) and by making use of a single physical transmission mean. Synchronized multimedia data (e.g. synchronized video and audio transmission) are example of this kind of (time-sensitive) information. This dissertation proposes a framework for design and development of network distributed applications in the field of automotive infotainment, compliant with the industry standards and using FPGA technology in order to ensure the system requirements satisfaction and promote IP Core re-utilization.A evolução natural dos sistemas embebidos traduziu-se numa maior rapidez na execução de tarefas, a possibilidade de incluir mais funcionalidades, aliado a menores consumos energéticos e beneficiando de crescentes e elevadas taxas de integração ao nível de silício. A indústria automóvel não é excepção no que diz respeito à integração de tecnologia para as mais variadas aplicações, com ou sem tolerância à falha, em sistemas que vão desde entretenimento ou infotainment a sistemas relacionados com a estabilidade e segurança do veículo, como é exemplo as driver assists. Existem de vários sistemas independentes nos modernos veículos automóveis. Estes, combinados com a necessidade de centralização ao nível de interface com o utilizador, tornam imperativa a simplicidade da operação. Para tal, requerem a minimizaccão da intervenção do utilizador, promovendo o conforto e diminuindo a probabilidade de desconcentração durante o exercício de condução. Os mais modernos standards de redes de comunicação como é exemplo o MOST ou o FlexRay, permitem a compatibilidade de informação trocada entre sistemas que comunicam através de distintos protocolos de comunicação. Para além disso, ainda garantem a coexistência de informação de controlo, informação do entretenimento e informação do tipo time-sensitive, onde os requisitos de temporização devem ser assegurados, mantendo uma qualidade de serviço fiàvel e fazendo uso de um único meio físico de transmissão. São exemplos deste tipo de informação, dados síncronos do tipo multimédia (e.g. streaming de àudio e vídeo de forma sincronizada). Pretende-se desenvolver uma framework para desenvolvimento de aplicações de rede distribuídas, do tipo infotainment e que beneficia a aplicação de tecnologias como FPGA, no offloading de computação para este dispositivo, como meio de garantir a satisfação dos requisitos, e promover a reutilização deste tipo de sistemas, mantendo o elevado desempenho na troca de dados e promovendo a portabilidade e a modularidade

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Social work with airports passengers

Social work at the airport is in to offer to passengers social services. The main methodological position is that people are under stress, which characterized by a particular set of characteristics in appearance and behavior. In such circumstances passenger attracts in his actions some attention. Only person whom he trusts can help him with the documents or psychologically

CORPORATE SOCIAL RESPONSIBILITY IN ROMANIA

The purpose of this paper is to identify the main opportunities and limitations of corporate social responsibility (CSR). The survey was defined with the aim to involve the highest possible number of relevant CSR topics and give the issue a more wholesome perspective. It provides a basis for further comprehension and deeper analyses of specific CSR areas. The conditions determining the success of CSR in Romania have been defined in the paper on the basis of the previously cumulative knowledge as well as the results of various researches. This paper provides knowledge which may be useful in the programs promoting CSR.Corporate social responsibility, Supportive policies, Romania