Infoscience
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Repository of the publications, research reports, PhD Theses, Ms Theses, semester works, lectures, etc., of the Facultés, Laboratories and Researchers at the EPFL.
Mostrando recursos 1 - 20 de 1.106
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Designing New Network Adaptation and ATM Adaptation Layers for Interactive Multimedia Applications - Garcia, Xavier
Multimedia services, audiovisual applications composed of a combination of discrete and continuous data streams, will be a major part of the traffic flowing in the next generation of high speed networks. The cornerstones for multimedia are Asynchronous Transfer Mode (ATM) foreseen as the technology for the future Broadband Integrated Services Digital Network (B-ISDN) and audio and video compression algorithms such as MPEG-2 that reduce applications bandwidth requirements. Powerful desktop computers available today can integrate seamlessly the network access and the applications and thus bring the new multimedia services to home and business users. Among these services, those based on multipoint...
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Differentiated Services on Linux - Salim, Jamal Hadi; Kuznetsov, Alexey; Almesberger, Werner
Recent Linux kernels offer a wide variety of traffic control functions, which can be combined in a modular way. We have designed support for Differentiated Services based on the existing traffic control elements, and we have implemented new components where necessary. In this document we give a brief overview of the structure of Linux traffic control, and we describe our prototype implementation in more detail.
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Scalable Resource Reservation for the Internet - Almesberger, Werner
For some time now, the design of architectures for providing dependable Quality of Service (QoS) on multimedia networks has been a busy topic in academia and industry. In this work we look at practical aspects of Quality of Service, and in particular at resource reservation for the Internet. Initially, our focus was on ATM, which looked like the most promising QoS technology at the time. We proposed, implemented, and demonstrated Arequipa, a mechanism that uses ATM to provide QoS for TCP/IP, and which only requires end-to-end connectivity, but no changes in the ATM network. While ATM still has its place,...
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Remote Data Acquisition Of Embedded Systems Using Internet Technologies: A Role-based Generic System Specification - Nieva, Txomin
Data Acquisition Systems (DAS) are the basis for building monitoring tools that enable the supervision of local and remote systems. DASs are complex systems. It is difficult for developers to compare proprietary generic DAS products and/or standards, and the design of a specific DAS is costly. In this thesis we propose an implementation independent specification, based on conceptual and role-based use case modeling, of a generic architecture for DASs. This generic DAS specification gives DAS developers an abstraction of DASs, it enables them to compare existing DAS products and standards, and it provides the DAS developers that aim to develop...
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Renegotiable Quality of Service - Giordano, Silvia
In this work we address the problem of supporting the QoS requirements for applications while efficiently allocating the network resources.We analyse this problem at the source node where the traffic profile is negotiated with the network and the traffic isshaped according to the contract.We advocate VBR renegotiation as an efficient mechanism toaccommodate traffic fluctuations over the burst time-scale. This is in line with the Integrated Service of the IETF with the Resource reSerVation Protocol (RSVP), where the negotiated contract may be modified periodically.In this thesis, we analyse the fundamental elements needed for solving the VBR renegotiation.A source periodically estimates the...
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Triune Continuum Paradigm: a paradigm for General System Modeling and its applications for UML and RM-ODP - Naumenko, Andrey
This thesis presents the structural organization, theoretical foundations and basic application principles of Triune Continuum Paradigm, an original paradigm applicable to object-oriented modeling. The paradigm defines a metamodeling structure efficient in the scope of general system modeling, in particular for object-oriented frameworks. This structure is rigorous and at the same time flexible. It allows the definition of formal ontologies for various specific object-oriented frameworks, for example for Unified Modeling Language (UML) or for Reference Model of Open Distributed Processing (RM-ODP is an ISO/ITU standard). Thus different existing frameworks, like UML or RM-ODP, can benefit from the logical rigor, internal consistency,...
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Building Blocks for Secure Services: Authenticated Key Transport and Rational Exchange Protocols - Buttyan, Levente
This thesis is concerned with two security mechanisms: authenticated key transport and rational exchange protocols. These mechanisms are potential building blocks in the security architecture of a range of different services. Authenticated key transport protocols are used to build secure channels between entities, which protect their communications against eavesdropping and alteration by an outside attacker. In contrast, rational exchange protocols can be used to protect the entities involved in an exchange transaction from each other. This is important, because often the entities do not trust each other, and both fear that the other will gain an advantage by misbehaving. Rational...
11.
Load Sharing for Multiprocessor Network Nodes - Kencl, Lukas
This thesis discusses techniques for sharing the processing load among multiple processing units within systems that act as nodes in a data communications network. Load-sharing techniques have been explored in the field of computer science for many years and their beneits are well known, including better utilization of processing capacity and enhanced system fault tolerance. We discuss deploying such methods in the specifics of the networking environment. We concentrate particularly on the data plane, or the data packet-processing tasks. After reviewing the main results in the fields of load sharing and multiprocessor networking systems architectures, we conduct a preparatory optimization...
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Delay Aspects in Internet Telephony - Boutremans, Catherine
In this work, we address the transport of high quality voice over the Internet with a particular concern for delays. Transport of interactive audio over IP networks often suffers from packet loss and variations in the network delay (jitter). Forward Error Correction (FEC) mitigates the impact of packet loss at the expense of an increase of the end-to-end delay and the bit rate requirement of an audio source. Furthermore, adaptive playout buffer algorithms at the receiver compensate for jitter, but again this may come at the expense of additional delay. As a consequence, existing error control and playout adjustment schemes...
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A Systemic Paradigm for Early IT System Requirements Based on Regulation Principles: The Lightswitch Approach - Regev, Gil
IT system is a general term for all software based business applications used in enterprises. IT systems support the actions of an enterprise by processing information about the enterprise and its environment and by providing this information to the enterprise and its stakeholders. An enterprises actions have a direct influence on its ability to succeed in its environment. IT systems, therefore, have a direct influence on the enterprises long term success. Hence, IT systems are considered to be of strategic importance in most contemporary enterprises. Although enterprises, most of the time, attempt to maintain their identity, forces within them and...
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Coping With Misbehavior in Mobile Ad-hoc Networks - Buchegger, Sonja
In this work, we address the question of how to enable a system to operate despite the presence of misbehavior. Specifically, in a mobile ad-hoc network, how can we keep the network functional for normal nodes when other nodes do not route and forward correctly? Node misbehavior due to selfish or malicious reasons or faulty nodes can significantly degrade the performance of mobile ad-hoc networks. Existing approaches such as economic incentives or secure routing by cryptographic means alleviate some of the problems, but not all. For instance, nodes can still forward packets on bogus routes. We propose a protocol called...
19.
Friction Modeling, Identification and Compensation (PhD Thesis) - Altpeter, F.
Abstract HIGH-PRECISION tracking requires excellent control of slow motion and positioning. Recent advances have provided dynamic friction models that represent almost all experimentally observed properties of friction. The state space formulation of these new mathematical descriptions has the property that the state derivatives are continuous functions. This enables the application of established theories for nonlinear systems. The existence of locally stable fixed points does not imply for nonlinear systems the absence of limit cycles (periodic orbits) or unstable solutions. Therefore, global properties of PI velocity and PID position control are analyzed using a passivity and Lyapunov based approach. These linear...
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