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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.
181

PERFORMANCE EVALUATION OF ETHERNET LAN BASED DISTRIBUTED TELEMETRY DATA NETWORK AND ITS EXTENSION USING ROUTER AND BRIDGE

Sadhukhan, Gautam, Vinodia, Deepak, Sandhu, Manmohan 10 1900 (has links)
International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / This paper evaluates the performance as well as effectiveness of the High Speed Ethernet LANBased Distributed Telemetry Data Network Architecture. It also attempts to obtain a feasible solution for the Extension of LAN over High Performance Digital Modem via Routers and Bridges. With the advent of highly efficient broadband TCP/IP network and rapid growth of data traffic demand in the area of Telemetry Data Acquisition and Processing, one has to adopt a high bit rate PCM Telemetry Data Stream with the strategy of distributed task scheduling in multiprocessor environment. The proposed Telemetry System Architecture is adopted as a milestone to Modern Telemetry system. It incorporates various value added services for the performance evaluation of various flight vehicles providing authenticated data. This paper shows that by configuring the IP addresses of various nodes and router / bridges with V.35 interfaces, it is possible to extend the Telemetry Data on a local LAN to the remote LAN for display and high speed processing in real time. Necessary comparisons of performance of the existing to the proposed systems are presented.
182

Managing Instrumentation Networks

Pesciotta, Eric 10 1900 (has links)
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / As traditional data acquisition systems give way to network-based data acquisition systems a new approach to instrumentation configuration, management and analysis is required. Today, most flight test programs are supported by traditional instrumentation systems and software. Pockets of network-based systems exist but are typically entirely new, closed systems. Relatively soon, test articles will emerge with a mixture of equipment. The merger of traditional and networked instrumentation is inevitable. Bridging the gap in software tools is a non-trivial task. Network-based data acquisition systems provide expanded flexibility and capabilities well beyond traditional systems. Yet pre-existing equipment requires traditional configuration and analysis tools. Traditional flight test software alone cannot fully exploit the added benefits gained from such mergers. The need exists for a new type of flight test software that handles existing instrumentation while also providing additional features to manage a network of devices. Network management is new to flight test software but a thoughtful implementation can facilitate easy transition to these modern systems. This paper explores the technologies required to satisfy traditional system configuration as well as the less understood aspects of network management and analysis. Examples of software that meet or exceed these requirements are provided.
183

REAL-TIME DATA SERVER-CLIENT SYSTEM FOR THE NEAR REAL-TIME RESEARCH ANALYSIS OF ENSEMBLE DATA

Ng, Sunny, Wei, Mei Y., Somes, Austin, Aoyagi, Mich, Leung, Joe 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper describes a distributed network client-server system developed for researchers to perform real-time or near-real-time analyses on ensembles of telemetry data previously done in post-flight. The client-server software approach provides extensible computing and real-time access to data at multiple remote client sites. Researchers at remote sites can share similar information as those at the test site. The system has been used successfully in numerous commercial, academic and NASA wide aircraft flight testing.
184

THE IMPLEMENTATION OF NASA’s LOW EARTH ORBITER – TERMINAL AS AN AUTONOMOUS GROUND NETWORK ASSET

Bundick, Steven N., Kremer, Steven E. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / As part of NASA’s goal to reduce costs for satellite telemetry and command ground support, the ground network has installed two autonomous ground terminals known as Low Earth Orbiter - Terminal’s, or LEO-T’s. These systems are highly automated and were developed to prove the feasibility of supporting multi-mission satellites in a handsoff mode.
185

Contribution a la téléoperation de robots en présence de délais de transmission variables

Leleve, Arnaud 12 December 2000 (has links) (PDF)
Les progrès en informatique permettent désormais d'effectuer des téléopérations via des réseaux informatiques. Par exemple, l'Internet a déjà été utilisé ces dernières années dans le cadre de téléopérations à longue distance. Il a l'énorme avantage d'être très répandu, accessible, fiable et économique. Le but de ce travail est de mettre en œuvre une plate-forme de téléopération à longue distance via des réseaux informatiques présentant les mêmes limitations que l'Internet : présence de retards, qui plus est variables dans le temps à petite (ms) et grande échelle de temps (mn), pertes de données, asymétrie des retards. Nous avons donc élaboré dans un premier temps un modèle mathématique d'une boucle de téléopération classique en partant d'expérimentations sur notre manipulateur mobile. Nous avons ainsi construit un simulateur qui nous a permis de nous attaquer à différents problèmes inhérents à une téléopération à longue distance. Enfin, nous développons un schéma de commande intégrant les diverses évolutions proposées applicable sur un bras manipulateur. Pour valider ce schéma expérimentalement, nous avons développé un ensemble logiciel de téléopération pour PC sous Microsoft Windows.
186

Techniques and countermeasures of TCP/IP OS fingerprinting on Linux Systems

Stopforth, Riaan. January 2007 (has links)
Port scanning is the first activity an attacker pursues when attempting to compromise a target system on a network. The aim is to gather information that will result in identifying one or more vulnerabilities in that system. For example, network ports that are open can reveal which applications and services are running on the system. How a port responds when probed with data can reveal which protocol the port utilises and can also reveal which implementation of that protocol is being employed. One of the most valuable pieces of information to be gained via scanning and probing techniques is the operating system that is installed on the target. This technique is called operating system fingerprinting. The purpose of this research is to alert computer users of the dangers of port scanning, probing, and operating system fingerprinting by exposing these techniques and advising the users on which preventative countermeasures to take against them. Analysis is performed on the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Internet Protocol (IPv4 and IPv6), and the Internet Control Message Protocol (ICMPv4 and ICMPv6). All the software used in this project is free and open source. The operating system used for testing is Linux (2.4 and 2.6 kernels). Scanning, probing, and detection techniques are investigated in the context of the Network Mapper and Xprobe2 tools. / Thesis (M.Sc. - Computer)-University of KwaZulu-Natal, Durban, 2007.
187

TCP in Wireless Networks: Challenges, Optimizations and Evaluations

Alfredsson, Stefan January 2005 (has links)
This thesis presents research on transport layer behavior in wireless networks. As the Internet is expanding its reach to include mobile devices, it has become apparent that some of the original design assumptions for the dominant transport protocol, TCP, are approaching their limits. A key feature of TCP is the congestion control algorithm, constructed with the assumption that packet loss is normally very low, and that packet loss therefore is a sign of network congestion. This holds true for wired networks, but for mobile wireless networks non-congestion related packet loss may appear. The varying signal power inherent with mobility and handover between base-stations are two example causes of such packet loss. This thesis provides an overview of the challenges for TCP in wireless networks together with a compilation of a number of suggested TCP optimizations for these environments. A TCP modification called TCP-L is proposed. It allows an application to increase its performance, in environments where residual bit errors normally give a degraded throughput, by making a reliability tradeoff. The performance of TCP-L is experimentally evaluated with an implementation in the Linux kernel. The transport layer performance in a 4G scenario is also experimentally investigated, focusing on the impact of the link layer design and its parameterization. Further, for emulation-based protocol evaluations, controlled packet loss and bit error generation is shown to be an important aspect.
188

Programming Memory-Constrained Networked Embedded Systems. PhD thesis

Dunkels, Adam January 2007 (has links)
Ten years after the Internet revolution are we standing on the brink of another revolution: networked embedded systems that connect the physical world with the computers, enabling new applications ranging from environmental monitoring and wildlife tracking to improvements in health care and medicine. 98% of all microprocessors sold today are used in embedded systems. Those systems have much smaller amounts of memory than PC computers. An embedded system may have as little has a few hundred bytes of memory, which makes programming them a challenge. This thesis focus on three topics regarding programming memory-constrained networked embedded systems: the TCP/IP for memory-constrained networked embedded systems, simplifying event-driven programming of memory-constrained systems, and dynamic loading of program modules in my Contiki operating system for memory-constrained systems. I show that the TCP/IP protocol stack can, contrary to previous belief, be used in memory-constrained embedded systems by implementing two small TCP/IP protocol stacks, lwIP and uIP. I present a novel programming mechanism called protothreads that I show significantly reduce the complexity of event-driven programming for memory-constrained systems. Protothreads provide a conditional blocked wait mechanism on top of event-driven systems with a much smaller memory overhead than full multithreading; each protothread requires only two bytes of memory. I show that dynamic linking of native code in standard ELF object code format is doable and feasible for wireless sensor networks by implementing a dynamic linker in the Contiki operating system. The results show that the energy overhead of dynamic linking of ELF files mainly is due to the ELF file format and not due to the dynamic linking mechanism as such. The impact of the research in this thesis has been and continues to be large. The software I have developed as part of this thesis is currently used by hundreds of companies in embedded devices in such diverse systems as car engines and satellites. The papers in this thesis are included as required reading in advanced courses on networked embedded systems and wireless sensor networks. / Contiki / uIP / Protothreads
189

Diseño de una red de vigilancia residencial basado en el protocolo de comunicación IP sobre las líneas eléctricas de baja tensión / César Manuel Garay Kaneshima

Garay Kaneshima, César Manuel 09 May 2011 (has links)
La elaboración de este documento parte de dos premisas claramente visibles en el entorno sobre el cual nos desarrollamos. La primera de ellas tiene su origen en la sociedad, se desenvuelve negativamente al interior de las instancias que la componen y actúa de tal manera, que cualquier estudio que busque demostrar sus consecuencias adquiere casi de inmediato un cierto nivel de insignificancia frente a lo cotidianamente experimentado. La segunda premisa parte de un fenómeno también social y que ha adquirido carácter masivo con el transcurrir de las últimas décadas; su expansión y desarrollo, por el contrario, son auspiciosos dado que sus objetivos están orientados a resolver problemas. / Tesis
190

Diseño del sistema de servicios de telecomunicaciones para el sitio arqueológico-turístico de Caral

Neyra Arbildo, Héctor Julio César 13 June 2011 (has links)
El desarrollo de las telecomunicaciones en los últimos años se viene orientando a la aplicación de nuevas tecnologías de alta capacidad de transmisión, dirigidas a mejorar la calidad y a aumentar la cantidad de servicios brindados tales como telefonía, multimedia, videoconferencia, Internet, entre otros. Las cuales destacan las inalámbricas como Wi-Fi y WiMAX por su fácil instalación y bajo costo. Surge así, la posibilidad de aplicar dichas tecnologías a la demanda de comunicaciones que requieren los habitantes de un lugar ausente de ellas. Por ello, el presente proyecto de tesis consiste en proponer el diseño de una plataforma de servicios de telecomunicaciones: telefonía fija, telefonía pública e Internet al sitio arqueológico y turístico de Caral, el cual no cuenta con tales servicios y los demanda cada día más debido al creciente número de turistas que atrae, trayendo como consecuencia brindarles las facilidades de comunicación en todo momento, y así activar económicamente a su población, a los establecimientos turísticos y a las actividades comerciales de la zona. De esta manera, se propone la tecnología de telecomunicaciones más adecuada para cubrir esta demanda y lograr su conectividad a todo el mundo. Este trabajo de tesis se divide en 4 capítulos: el primer capítulo consiste en el estudio de la demanda demográfica de turistas y del tráfico que requerirán los servicios de telecomunicaciones en el centro turístico de Caral. En el segundo capítulo, se analizan las mejores alternativas tecnológicas inalámbricas para la plataforma de acceso a red de Caral, haciendo un estudio del estándar WiMAX y una comparación con el estándar Wi-Fi. En el tercer capítulo, se desarrolla la ingeniería del proyecto, es decir, el diseño de la red total a implementar en el centro arqueológico de Caral, eligiendo la tecnología a usar, la marca y los equipos de telecomunicaciones más adecuados a la misma. Por último, el cuarto capítulo, consiste en un análisis de los costos de inversión, operación y mantenimiento de la red puesta ya en marcha, brindando los servicios de telecomunicaciones y revisando a la vez la factibilidad y tiempo de recuperación de la inversión que implicó hacer este proyecto completo. Finalmente, se presentan las conclusiones de este proyecto, producto del desarrollo de la presente tesis. / Tesis

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