Дисертації з теми "Network convergence"
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1
Liu, Siqian. "Network Convergence in Multicarrier Hybrid Cellular Network." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27505.
Анотація:
In a multicarrier communication system with known channel state information at transmitter (CSIT), it is well-known that the water-filling power allocation scheme is optimal in achieving the Shannon capacity. However, in a multicarrier broadcast network (e.g. over-the-air TV network) without CSIT, the optimal power allocation among subcarriers is still unknown, largely due to the heterogeneity of the channel conditions associated with different receivers. In the first part of the thesis, the performance of a generic multicarrier broadcast network is thoroughly studied by exploiting the frequency diversity over subcarriers. In particular, the performance metric is first defined based on the relationship among broadcast transmission rate, coverage area and outage probability. In order to maximize the network performance, closed form expressions of the instantaneous mutual information (IMI) and the optimal power allocation schemes are derived for both low SNR and high SNR cases; upper and lower bounds are also provided to estimate broadcast coverage area in general SNR regime. Also we extend our discussion to the broadcast network with multiple collaborative transmitters. Extensive simulation results are provided to validate our analysis. In the second part of the thesis, we discuss the optimal performance of a generic broadcast cellular hybrid network. It is well known that the Dirty Paper Coding (DPC) achieves the channel capacity for multiuser degraded channels. However, the optimality of DPC remains unknown for non-degraded channel. Specifically, we derive the optimal interference pre-cancellation order for a DPC based broadcast and unicast hybrid network. Different DPC cancellation schemes are studied to maximize the hybrid capacity region. The conditions for each scheme being optimal are analytically derived. Both ergodic and outage capacity are considered as our performance metric. Our results show that the optimal interference pre-cancellation order varies with SNR and broadcast and unicast channel conditions. Moreover, in low SNR condition, the optimal power allocation scheme is derived to reach the maximal sum rate.
2
VAFA, FARZAM. "M2M AND LTE-A NETWORK CONVERGENCE." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/988.
Анотація:
In this thesis we provide a feasible solution for converging Machine to machine (M2M) networks and 3gpp Long Term Evolution advanced (LTE-A) Network. As a M2M network, a Wireless Sensor Network (WSN) is chosen. In order to overcome the power consumption restriction in M2M communication, IPv6 Low Power Personal Area Network (6LoWPAN) standard is used over IEEE 802.15.4 interface. A dual mode gateway structure is proposed for integration of two networks. One side of the gateway is connected to the M2M network, and the other side is the User Equipment (UE) which is the last node of LTE access layer. In term of Network convergence, Tight Coupling is preferred to decrease the expected end to end latency. The proposed structure is implemented in OMNET++ simulator.
3
Sridharan, Vidhumana. "Enterprise network convergence : path to cost optimization /." Online version of thesis, 2007. http://hdl.handle.net/1850/4393.
4
LeBlanc, Robert-Lee Daniel. "Analysis of Data Center Network Convergence Technologies." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4150.
Анотація:
The networks in traditional data centers have remained unchanged for decades and have grown large, complex and costly. Many data centers have a general purpose Ethernet network and one or more additional specialized networks for storage or high performance low latency applications. Network convergence promises to lower the cost and complexity of the data center network by virtualizing the different networks onto a single wire. There is little evidence, aside from vendors' claims, that validate network convergence actually achieves these goals. This work defines a framework for creating a series of unbiased tests to validate converged technologies and compare them to traditional configurations. A case study involving two different network converged technologies was developed to validate the defined methodology and framework. The study also shows that these two technologies do indeed perform similarly to non-virtualized network, reduce costs, cabling, power consumption and are easy to operate.
5
Danielsson, Jakob, and Tobias Andersson. "Investigating Methods For Measuring Network Convergence Times." Thesis, Mälardalens högskola, Inbyggda system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-31822.
Анотація:
This thesis investigates different methods that can be used for analyzing network performance and,ultimately, can be used for measuring the convergence time of ring coupled networks. As of today,many networks are often run with extra links, serving as backup links in case any that of the mainlinks would go down. To operate networks with backup links in layer 2 and layer 3, specific re-routing protocols such as RIP and OSPF are used in order to calculate a feasible path through anetwork when a network state changes. Depending on different implementations of the protocolsand the hardware used, the convergence times can vary substantially, which means measuring thenetwork performance is a very important part when developing a network solution. To executenetwork tests, a packet engine suite is used consisting of a network traffic generator that is used forcreating a packet stream, as well as a traffic receiver that fetches the packets sent. Various types ofengines can be used including Linux based, real-time operating systems based and bare-metal basedsolutions. From these different types of engines, a few tools are chosen and investigated on differentproperties including performance and usability. It was found that Tshark (Linux, RT-Linux based),USPI (Raspberry Pi bare metal), FreeRTOS (Raspberry Pi based), Arduino and PKTgen (Linuxkernel based) were the most suitable approaches to be used for testing. The test parameters includetesting the gaps between packets, maximum jitter, average jitter and packets sent per second. Thesetests revealed that an IXIA solution was slightly more accurate when used as a receiving end sinceit produced less jitter, however this difference could only be noticed in a micro second range. Itwas also revealed that it produced slightly less jitter than the other packet generators, also here onlynoticeable in a microsecond range. Thus it can be concluded that IXIA is not much superior any ofthe close to hardware solutions. The executed network tests revealed that the Westermo developedlayer 2 protocol FRNT generated less network convergence time and less packet losses than thecommonly used RSTP protocol. Similar tests against the layer 3 protocols revealed that RIP wasmuch faster than OSPF and it also lost less packets. Finally it is concluded that there is no needto buy an expensive network testing suite to test the convergence time of a network. Instead, anetwork testing suite can be developed with minimal funding.
6
Possne, Jacob. "Network Convergence or Divergence? : A service perspective on the underlying requirements of future handsets." Thesis, KTH, Kommunikationssystem, CoS, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92182.
Анотація:
Network Convergence or Divergence, what is it, and which are the most likely developments? Today, a much talked about area of telecommunications is the move toward the IP Multimedia Subsystem (IMS), and with it the introduction of IP-based communication in both Public Land Mobile Networks and Public Switched Telephony Networks. This thesis attempts to show whether these two networks will converge with each other and with the Internet in the future - based upon the existence of a few important prerequisites in terms of standards and protocols, whilst divergence in the networks could result if technical and economical obstacles are difficult to circumvent or to exclude from future networks. The major drivers for convergence include the existence of standards for packet-based transmission over a wide variety of underlying networks, the existence of services that make use of these underlying networking protocols, and ultimately also the existence of devices that can use the new features of a converged network architecture. The focus is on the impact convergence services or offerings may have on handsets; specifically which protocols need to be supported, as well as those hardware and software requirements that need to be catered for to enable convergence in the handset sector. The thesis concludes with a summary of the most important factors for convergence in future mobile handsets.Nätkonvergens eller divergens, vad är det egentligen, och var är utvecklingen på väg? Idag talas det mycket om inom telekommunikationsbranchen om steget till IMS (IP Multimedia Subsystem), och i med det övergången till uteslutande IP-baserad kommunikation i både Public Land Mobile Networks och Public Switched Telephony Networks. Jag ämnar i den här framställningen visa att konvergens mellan dessa två nät samt ett tredje; Internet är avhängigt av ett par viktiga grundförutsättningar, som existensen av protokoll och standarder som främjar konvergens, medan en divergerande utveckling är resultatet av tekniska och ekonomiska förutsättningar som är svåra att kringgå i framtida nät. De stora drivkrafterna för konvergens är existensen av standarder och protokoll för paketbaserad överföring av data över skiftande nätarkitekturer, existensen av tjänster som stödjer dessa protokoll, och slutligen användarterminaler som förmår utnyttja dessa tjänster utvecklade för en konvergerande nättopologi. Fokus för min rapport är på det stöd som behövs i terminalerna för att en sådan här utveckling ska kunna äga rum. Kapaciteten i form av protokoll som dessa terminaler måste stödja, samt vilka hård- och mjukvarukrav som måste uppfyllas kommer också att behandlas. Slutligen kommer jag att framställa en sammanfattning av vad jag anser vara de viktigaste faktorerna i framtida terminaler för att driva den här utvecklingen.
7
Weir, Malcolm. "TECHNOLOGY CONVERGENCE: OBSERVATIONS ON TRANSITIONAL APPROACHES FOR DATA ACQUISITION IN A TCP/IP ENVIRONMENT." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604539.
Анотація:
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThis paper discusses how IRIG 106 Chapter 10 recording techniques could be employed in a network-centric environment, while maintaining as many of the strengths of the traditional approach. In the course of that discussion, aspects of the published standard which would have to be disregarded or reinterpreted for a network-centric approach to be adopted are illustrated.
8
Terelius, Håkan, Guodong Shi, Jim Dowling, Amir Payberah, Ather Gattami, and Karl Henrik Johansson. "Converging an Overlay Network to a Gradient Topology." KTH, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-46515.
Анотація:
In this paper, we investigate the topology convergence problem for the gossip-based Gradient overlay network. In an overlay network where each node has a local utility value, a Gradient overlay network is characterized by the properties that each node has a set of neighbors containing higher utility values, such that paths of increasing utilities emerge in the network topology. The Gradient overlay network is built using gossiping and a preference function that samples from nodes using a uniform random peer sampling service. We analyze it using tools from matrix analysis, and we prove both the necessary and sufficient conditions for convergence to a complete gradient structure, as well as estimating the convergence time. Finally, we show in simulations the potential of the Gradient overlay, by building a more efficient live-streaming peer-to-peer (P2P) system than one built using uniform random peer sampling.© 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111124
9
Gregory, Jessica G. "A Rate of Convergence for Learning Theory with Consensus." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51263.
Анотація:
This thesis poses and solves a distribution free learning problem with consensus that arises in the study of estimation and control strategies for distributed sensor networks. Each node i for i = 1, . . . , n of the sensor network collects independent and identically distributed local measurements {z i} := {z i j}j∈N := {(x i j , yi j )}j∈N ⊆ X × Y := Z that are generated by the probability measure ρ i on Z. Each node i for i = 1, . . . , n of the network constructs a sequence of estimates {f i k }k∈N from its local measurements {z i} and from information functionals whose values are exchanged with other nodes as specified by the communication graph G for the network. The optimal estimate of the distribution free learning problem with consensus is cast as a saddle point problem which characterizes the consensus-constrained optimal estimate. This thesis introduces a two stage learning dynamic wherein local estimation is carried out via local least square approximations based on wavelet constructions and information exchange is associated with the Lagrange multipliers of the saddle point problem. Rates of convergence for the two stage learning dynamic are derived based on certain recent probabilistic bounds derived for wavelet approximation of regressor functions.Master of Science
10
Frank, Florian. "Hybrid analogue & digital access network architectures for the mobile/fixe infrastructure convergence." Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00665650.
Анотація:
In order to realize the convergence of the optical infrastructure of fixed and mobile access networks, the objective of this thesis is to study the solutions for distributing native radio carriers through typical optical access networks.The first Part describes the contexts and the main physical properties of the optical and radio access networks: from nowadays deployed Fiber To The Home (FTTH) systems, and their expected evolutions, to the current radio system Universal Mobile Telecommunications System (UMTS) towards the expected requirements of modern mobile radio systems. This allows to settle the optical environment in which the Radio over Fiber(RoF)-functionalities will have to be integrated, and to know on which radio systems'figures of merits to focus on when implementing it. The second Part shows the benefit and possibilities of re-using the optical infrastructure of the fixed access networks for distributed radio systems. Then a review of the analog and digital RoF techniques is proposed, and their feasibility of integration into legacy FTTH systems is discussed. The third part deals with the computing and simulations of an analog RoF-system where the optical link is either passive or optically pre-amplified, and even boosted. The goal is to provide numerical results to the practical lab. results of the second half of the fourth part where the Signal to Noise Ratio (SNR) matters. Therefore successively formal expressions, numerical results for simple 2-tone signals and more realistic UMTS signals are considered. The fourth and last part deals with the obtained practical results. These can be split into two main categories : Error Vector Magnitude (EVM)-oriented results where an Avalanche Photo-Detector (APD) is used for legacy and extended-reach PON architectures using a direction shared Semiconductor Optical Amplifier (SOA) ; and an Adjacent/Alternate Channel power Leakage Ratio (ACLR)-driven part where the focus is seton a very critical figure of merit of radio systems, especially in the downlink. The latter part turned out to be mandatory and prevailing over the initially considered EVM concerns. Hence several RoF architectures, compatible with PONs, are introduced in order to overcome the non-linearities undergone by the RoF-signals, induced by the chromatic dispersion of the PON's fiber and the laser chirp, and degrading the ACLR performances
11
Kramer, Jeremy Daniel. "Min-Cost Multicommodity Network Flows: A Linear Case for the Convergence and Reoptimization of Multiple Single-Commodity Network Flows." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04242009-204158/.
Анотація:
Network Flow problems are prevalent in Operations Research, Computer Science, Industrial Engineering and Management Science. They constitute a class of problems that are frequently faced by real world applications, including transportation, telecommunications, production planning, etc. While many problems can be modeled as Network Flows, these problems can quickly become unwieldy in size and difficult to solve. One particularly large instance is the Min-Cost Multicommodity Network Flow problem. Due to the time-sensitive nature of the industry, faster algorithms are always desired: recent advances in decomposition methods may provide a remedy. One area of improvement is the cost reoptimization of the min-cost single commodity network flow subproblems that arise from the decomposition. Since similar single commodity network flow problems are solved, information from the previous solution provides a "warm-start" of the current solution. While certain single commodity network flow algorithms may be faster "from scratch," the goal is to reduce the overall time of computation. Reoptimization is the key to this endeavor. Three single commodity network flow algorithms, namely, cost scaling, network simplex and relaxation, will be examined. They are known to reoptimize well. The overall goal is to analyze the effectiveness of this approach within one particular class of network problems.
12
Emschwiller, Matt V. "Understanding neural network sample complexity and interpretable convergence-guaranteed deep learning with polynomial regression." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127290.
Анотація:
Thesis: S.M., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, May, 2020Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-89).
We first study the sample complexity of one-layer neural networks, namely the number of examples that are needed in the training set for such models to be able to learn meaningful information out-of-sample. We empirically derive quantitative relationships between the sample complexity and the parameters of the network, such as its input dimension and its width. Then, we introduce polynomial regression as a proxy for neural networks through a polynomial approximation of their activation function. This method operates in the lifted space of tensor products of input variables, and is trained by simply optimizing a standard least squares objective in this space. We study the scalability of polynomial regression, and are able to design a bagging-type algorithm to successfully train it. The method achieves competitive accuracy on simple image datasets while being more simple. We also demonstrate that it is more robust and more interpretable that existing approaches. It also offers more convergence guarantees during training. Finally, we empirically show that the widely-used Stochastic Gradient Descent algorithm makes the weights of the trained neural networks converge to the optimal polynomial regression weights.
by Matt V. Emschwiller.
S.M.
S.M. Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center
13
Shanmugalingam, Sivasothy. "Convergence of web and communication services." Phd thesis, Institut National des Télécommunications, 2012. http://tel.archives-ouvertes.fr/tel-00997697.
Анотація:
Different communication services from delivery of written letters to telephones, voice/video over Internet Protocol(IP), email, Internet chat rooms, and video/audio conferences, immersive communications have evolved over time. A communication system of voice/video over IP is the realization of a two fundamental layered architecture, signaling layer and media layer. The signaling protocol is used to create, modify, and terminate media sessions between participants. The signaling layer is further divided into two layers, service layer and service control layer, in the IP Multimedia Subsystem (IMS) specification. Two widely used communication systems are IMS, and Peer-to-Peer Session Initiation Protocol (P2P SIP). Service providers, who behave as brokers between callers and callees, implement communication systems, heavily controlling the signaling layer. These providers do not take the diversity aspect of end users into account. This dissertation identifies three technical barriers in the current communication systems especially in the signaling layer. Those are: I. lack of openness and flexibility in the signaling layer for end users. II. difficulty of development of network-based, session-based services. III. the signaling layer becomes complex during the high call rate. These technical barriers hinder the end-user innovation with communication services. Based on the above listed technical barriers, the first part of this thesis defines a concept and architecture for a communication system in which an individual user becomes the service provider. The concept, My Own Communication Service Provider (MOCSP) and MOCSP system is proposed and followed by a call flow. Later, this thesis provides an analysis that compares the MOCSP system with existing communication systems in terms of openness and flexibility. The second part of this thesis presents solutions for network-based, session based services, leveraging the proposed MOCSP system. Two innovative services, user mobility and partial session transfer/retrieval are considered as examples for network-based, session-based services. The network-based, sessionbased services interwork with a session or are executed within a session. In both cases, a single functional entity between caller and callee consistently enables the media flow during the call initiation and/or mid-call. In addition, the cooperation of network call control and end-points is easily achieved. The last part of the thesis is devoted to extending the MOCSP for a high call rate and includes a preliminary comparative analysis. This analysis depends on four factors - scalability limit, complexity level, needed computing resources and session setup latency - that are considered to specify the scalability of the signaling layer. The preliminary analysis clearly shows that the MOCSP based solution is simple and has potential for improving the effective usage of computing resources over the traditional communication systems
14
Kück, Fabian [Verfasser], Dominic [Akademischer Betreuer] Schuhmacher, Dominic [Gutachter] Schuhmacher, and Anja [Gutachter] Sturm. "Convergence Rates in Dynamic Network Models / Fabian Kück ; Gutachter: Dominic Schuhmacher, Anja Sturm ; Betreuer: Dominic Schuhmacher." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-002E-E362-F-5.
15
Ding, Zhen. "A Static Traffic Assignment Model Combined with an Artificial Neural Network Delay Model." FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/51.
Анотація:
As traffic congestion continues to worsen in large urban areas, solutions are urgently sought. However, transportation planning models, which estimate traffic volumes on transportation network links, are often unable to realistically consider travel time delays at intersections. Introducing signal controls in models often result in significant and unstable changes in network attributes, which, in turn, leads to instability of models. Ignoring the effect of delays at intersections makes the model output inaccurate and unable to predict travel time. To represent traffic conditions in a network more accurately, planning models should be capable of arriving at a network solution based on travel costs that are consistent with the intersection delays due to signal controls. This research attempts to achieve this goal by optimizing signal controls and estimating intersection delays accordingly, which are then used in traffic assignment. Simultaneous optimization of traffic routing and signal controls has not been accomplished in real-world applications of traffic assignment. To this end, a delay model dealing with five major types of intersections has been developed using artificial neural networks (ANNs). An ANN architecture consists of interconnecting artificial neurons. The architecture may either be used to gain an understanding of biological neural networks, or for solving artificial intelligence problems without necessarily creating a model of a real biological system. The ANN delay model has been trained using extensive simulations based on TRANSYT-7F signal optimizations. The delay estimates by the ANN delay model have percentage root-mean-squared errors (%RMSE) that are less than 25.6%, which is satisfactory for planning purposes. Larger prediction errors are typically associated with severely oversaturated conditions. A combined system has also been developed that includes the artificial neural network (ANN) delay estimating model and a user-equilibrium (UE) traffic assignment model. The combined system employs the Frank-Wolfe method to achieve a convergent solution. Because the ANN delay model provides no derivatives of the delay function, a Mesh Adaptive Direct Search (MADS) method is applied to assist in and expedite the iterative process of the Frank-Wolfe method. The performance of the combined system confirms that the convergence of the solution is achieved, although the global optimum may not be guaranteed.
16
Qiu, Tongqing. "Understanding a large-scale IPTV network via system logs." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41228.
Анотація:
Recently, there has been a global trend among the telecommunication industry on the rapid deployment of IPTV (Internet Protocol Television) infrastructure and services. While the industry rushes into the IPTV era, the comprehensive understanding of the status and dynamics of IPTV network lags behind. Filling this gap requires in-depth analysis of large amounts of measurement data across the IPTV network. One type of the data of particular interest is device or system log, which has not been systematically studied before. In this dissertation, we will explore the possibility of utilizing system logs to serve a wide range of IPTV network management purposes including health monitoring, troubleshooting and performance evaluation, etc. In particular, we develop a tool to convert raw router syslogs to meaningful network events. In addition, by analyzing set-top box (STB) logs, we propose a series of models to capture both channel popularity and dynamics, and users' activity on the IPTV network.
17
Klekamp, Jesse Janice. "Intentioned Network Convergence: How Social Media is Redefining, Reorganizing, and Revitalizing Social Movements in the United States." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/scripps_theses/96.
Анотація:
This analysis seeks to understand the power of social media to create sustainable social movements. The 1999 World Trade Organization protests in Seattle were one of the first internet-supported acts of protest and illustrate the power of the Internet and social media to bring together diverse coalitions of actors and maintain decentralized power structures. Next, the analysis studies the non-profit advocacy organization Invisible Children and the recent media explosion of their Kony 2012 campaign to make sense of how uses of the Internet have expanded since 1999. The Kony 2012 case illustrates the power of committed networks in disseminating information but also alludes to some of the new challenges social media presents. Ultimately, this analysis concludes that social media has simultaneously empowered and crippled social media, calling for an intentioned use of the Internet applications, strong leadership, and cultural framing to sustain mobilization.
18
Tsianos, Konstantinos. "The role of the network in distributed optimization algorithms: convergence rates, scalability, communication/ computation tradeoffs and communication delays." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119626.
Анотація:
Many questions of interest in various fields ranging from machine learning to computational biology and finance require the solution of an optimization problem. Frequently such problems are classified as large scale in the sense that they involve complex computations over very large datasets. The increasing interest in distributed optimization algorithms is motivated by two main reasons. First, the problem complexity pushes today's processors to their limits and the need for distributed algorithms arises quite naturally. A second and more practical reason is that sometimes the data is collected in a distributed manner and transmitting it to a single location is either too costly or violates privacy. The starting point of this thesis is the simple realization that the main difference between a serial and a distributed algorithm is that in the latter, a processor needs to exchange messages over a network to access another processor's information. Network communication is in general less reliable and orders of magnitude slower than local disk accesses. Furthermore, in an arbitrary network topology to achieve global performance messages might need to travel over multiple hops. Finally, the hardware's capabilities also limit the ways in which a distributed algorithm may be implemented. All these factors highlight the important role of the network in distributed optimization algorithms. To understand that role we focus on the class of consensus-based distributed optimization algorithms. Those algorithms admit an elegant theoretical analysis while remaining easy to implement. In addition they tend to be scalable and robust to communication delays. The contributions of this work can be grouped into four important areas: 1) understanding the communication/computation tradeoff and its effect on scalability with the network size, 2) understanding the limitations of the network and the necessary features that distributed algorithms need to possess to be practical, 3) understanding the effects on convergence of network-induced communication delays and 4) understanding the theoretically achievable convergence rates of distributed algorithms. These areas impact the design and deployment of any consensus-based distributed optimization algorithm.Il y a une grande variété de domaines d'apprentissage automatique, de la biologie à la finance, où l'on doit résoudre des problèmes d'optimisation. Souvent ces problèmes impliquent des calculs complexes sur de vastes ensembles de données. Pour résoudre ces problèmes le développement d'algorithmes distribués est devenu très populaire pour deux raisons. Premièrement, la complexité des problèmes pousse les processeurs actuels à leurs limites. Naturellement, il devient essentiel d'utiliser des systèmes distribués. La deuxième raison est que la collecte des données est parfois distribuée, et il est difficile, coûteux ou en violation d'accords de confidentialité de transférer toutes les données au même endroit. La fondation de cette thèse est la réalisation simple que la grande différence entre un algorithme centralisé et un algorithme distribué est que ce dernier utilise un réseau pour permettre l'échange d'information d'un processeur à un autre. Généralement, la communication sur un réseau est moins fiable et beaucoup plus lente que l'accès d'information sur un disque local. De plus, pour une topologie de réseau arbitraire, la communication de messages nécessite plusieurs sauts. Finalement, les capacités matérielles aussi limitent les façons par lequelles les algorithmes distribués théoriques peuvent être mis en oeuvre. Tous ces facteurs, rappellent l'importance du réseau. Pour comprendre cette importance, nous nous concentrons, sur la classe des algorithmes de consensus pour optimisation distribuée. Ces algorithmes aussi possèdent des analyses théoriques très élégantes tout en restant faciles a mettre en oeuvre. Aussi, ils sont robustes aux délais de communication et extensibles. Les contributions de cette thèse peuvent être classifiées selon les quatres catégories suivantes: 1) comprendre le compromis entre communication et calculs locaux, et l'extensibilité avec la taille du réseau, 2) comprendre les limites posées par le réseau aux fonctionnalités nécessaires que chaque algorithme distribué doit possèder en pratique, 3) comprendre les effets de délais de communication et les propriétés de convergence de ces algorithmes en présence de délais, 4) comprendre les taux théoriques de convergence des algorithmes d'optimisation distribués. Tous ces domaines affectent la conception et le déploiement de chaque algorithme de consensus d'optimisation distribué.
19
McMorries, David W. "Investigation into the effects of voice and data convergence on a Marine Expeditionary Bridgade TRI-TAC digital transmission network." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA379684.
Анотація:
Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, June 2000.Thesis advisors, Osmundson, John S. ; Brady, Terrence C. "June 2000." Includes bibliographical references (p. 69). Also available in print.
20
Braun, Alina [Verfasser], Michael [Akademischer Betreuer] Kohler, and Volker [Akademischer Betreuer] Betz. "In Theory and Practice - On the Rate of Convergence of Implementable Neural Network Regression Estimates / Alina Braun ; Michael Kohler, Volker Betz." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/1238783104/34.
21
Talukder, Satyobroto. "Mathematicle Modelling and Applications of Particle Swarm Optimization." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2671.
Анотація:
Optimization is a mathematical technique that concerns the finding of maxima or minima of functions in some feasible region. There is no business or industry which is not involved in solving optimization problems. A variety of optimization techniques compete for the best solution. Particle Swarm Optimization (PSO) is a relatively new, modern, and powerful method of optimization that has been empirically shown to perform well on many of these optimization problems. It is widely used to find the global optimum solution in a complex search space. This thesis aims at providing a review and discussion of the most established results on PSO algorithm as well as exposing the most active research topics that can give initiative for future work and help the practitioner improve better result with little effort. This paper introduces a theoretical idea and detailed explanation of the PSO algorithm, the advantages and disadvantages, the effects and judicious selection of the various parameters. Moreover, this thesis discusses a study of boundary conditions with the invisible wall technique, controlling the convergence behaviors of PSO, discrete-valued problems, multi-objective PSO, and applications of PSO. Finally, this paper presents some kinds of improved versions as well as recent progress in the development of the PSO, and the future research issues are also given.
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Vasques, Vanessa Claudia. "Convergence of old and new: a case study analysis of the development online by a South African radio station: Radiosondergrense/www.rsg.co.za." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1003913.
Анотація:
This thesis is a case study analysis of the dream one radio station had about creating something new and unique on the Internet. RadioSonderGrense (RSG), an Afrikaans South African radio station, saw opportunities for themselves as a radio station on the Internet and put enormous resources and man-power into their venture. Their vision of what the Internet could bring to their radio station, and what they could bring to a website set the ground for creative and innovative thought. This dissertation is an examination of whether the Internet lived up to the expectations RSG had for it, and whether they were able to use their resources (in terms of their audience, their advertisers and the uniqueness of radio) to create something new and never seen before. The foremost aim of this dissertation is to shed some light onto the up-to-now under researched area of why radio stations have begun to develop on the Internet. Through the analysis of RSG, their comes to this subject some new thoughts and ideas about the convergence of these two mediums. RSG, and radio in general, are examined historically, practically and in comparison to the Internet. This is done in order to fully grasp the project that RSG had set for themselves and to realize where they had come from and where they hoped to go. It is argued that although RSG had hoped for great things, their innovative thought was not enough to guarantee them their dreams. They were not able to fully utilize the resources available to them in combination with what the Internet could offer them to fulfill the expectations they had for themselves. The foremost conclusion is that although RSG were able to envisage what the Internet could add to the radio station, they fell short of giving their listeners, users and advertisers a tool which could make the RSG website truly unique. Their website gives the user some interesting and useful applications, but it does not make full use of what the Internet and radio together could create.
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Cornillet, Nicolas. "Convergence des réseaux de télécommunications mobiles et de télédiffusion : modélisation et évaluation des performances d’un réseau hybride LTE/DVB-T2." Thesis, Rennes, INSA, 2013. http://www.theses.fr/2013ISAR0034/document.
Анотація:
Ces dernières années, la popularité croissante de terminaux mobiles de plus en plus intelligents a provoqué une hausse considérable du trafic supporté par les réseaux de télécommunications cellulaires. Dans ce contexte, le déploiement de réseaux dits de quatrième génération basés sur le standard LTE (Long Term Evolution) et offrant des capacités significativement plus élevées que les réseaux de générations précédentes peut sembler être une solution idéale. Cependant, dans le cas d’un service à délivrer à un très grand nombre d’utilisateurs, ce standard, malgré la disponibilité de la technologie eMBMS (Evolved Multimedia Broadcast Multicast Services), n’est pas forcément le plus adapté. Dans le même temps, la télévision a achevé dans de nombreux pays sa transition vers le numérique. L’abandon de la transmission analogique a permis non seulement d’améliorer la qualité du service mais aussi d’occuper moins de spectre. En France, une partie du spectre libéré a déjà été attribué au déploiement de réseaux LTE. Une autre méthode permettant d’exploiter ce spectre au profit des réseaux de communications mobiles est proposée dans cette thèse : le réseau hybride. Le réseau hybride est constitué d’un réseau cellulaire au standard LTE accompagné d’un émetteur DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial). Les aires de couverture de ces deux composantes se superposent et un service peut être transmis aux utilisateurs présents dans ces aires indifféremment par l’une ou l’autre des composantes. Ce concept permet de pallier un point faible du standard LTE, c’està- dire la capacité à délivrer efficacement un même service à un grand nombre d’utilisateurs simultanément. Après une étude approfondie des deux standards utilisés, un modèle mathématique du réseau hybride est proposé. Ce modèle se base sur les propriétés géométriques du réseau hybride, les performances des deux types de signaux utilisés, et sur plusieurs types de répartition des utilisateurs pour évaluer les performances du réseau hybride selon différents critères. Le premier critère étudié est un critère énergétique. Le modèle proposé permet de comparer les efficacités énergétiques des deux composantes pour transmettre un service en fonction de son nombre d’utilisateurs. L’efficacité de la composante DVBT2 dépasse celle de la composante LTE à partir d’un seuil dont la valeur varie avec les propriétés géométriques du réseau et le type d’affaiblissement de propagation auquel sont soumis les signaux. Il est de plus possible, dans certaines circonstances, d’améliorer encore l’efficacité énergétique du système en utilisant conjointement les deux composantes. Le second critère étudié est celui de l’encombrement du réseau cellulaire. En effet, un service consommé par un grand nombre d’utilisateurs peut avoir un impact conséquent sur le trafic à transmettre par un réseau LTE. Utiliser la composante DVB-T2 pour distribuer un tel service permet de réduire la charge du réseau cellulaire, et ceci même dans le cas où la composante DVB-T2 ne couvre pas l’ensemble de la zone à desservir globalement. Ces différentes études ont permis de bien mettre en évidence les avantages et inconvénients des deux types de réseaux broadcast et unicast. En particulier, l’intérêt d’une approche reposant sur l’utilisation d’un réseau hybride exploitant la complémentarité des deux composantes broadcast et unicast a été démontréDuring the last few years, the growing popularity of smarter and smarter mobile devices has led to a tremendous growth of cellular data traffic. In such a context, the deployment of fourth generation networks based on the LTE (Long Term Evolution) standard and with capacities significantly higher than previous generations networks can be seen as an ideal solution. However, when the number of users requiring a given service is large, this standard, despite the availability of the eMBMS (Evolved Multimedia Broadcast Multicast Services) technology, is not necessarily the most suitable. Meanwhile, television has completed its transition to the digital transmission in many countries. The analog switch-off has not only allowed a better quality of service but has also freed some spectrum. In France, some of this spectrum has already been used for the deployment of LTE networks. This thesis introduces another way to use this spectrum to the benefit of mobile data networks: the hybrid network. The hybrid network consists of a LTE cellular network and a DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial) transmitter. The coverage areas of the two components are overlapping and a service can be delivered to the users located in these areas by either one or the other of the components. This concept can compensate one weakness of the LTE standard, which is the ability to deliver efficiently the same service to a large number of users simultaneously. After a thorough study of the two standards in use, a mathematical model of the hybrid network is proposed. This model is based on the geometrical properties of the network, the performances of the two types of signal, and different types of users distribution to measure the performances of the hybrid network using different criteria. The first criterion is the energy efficiency. The proposed model allows the comparison of the two components in terms of energy efficiency for one service depending of the number of its users. The DVB-T2 component outperforms the LTE component when the number of users exceeds a given threshold whose value depends on the geometric properties of the network and the type of path loss attenuating the signals. It is possible, in some cases, to further improve the energy efficiency of the system by using both components together. The second criterion is the network congestion. Indeed, a service with a great number of users can induce significant data traffic for the LTE network. Transmitting such a service through the DVB-T2 component can decrease the cellular data traffic even if the DVB-T2 component does not cover the whole area of interest. These studies have brought out the benefits and drawbacks of both broadcast and unicast networks. Especially, the interest of the hybrid network based on the complementarities between the two components has been demonstrated
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Figueiredo, Vilar Ribeiro de. "Proposta de uma arquitetura de processamento distribuído aberto para aplicações em um escritório móvel convergente." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-29092006-114229/.
Анотація:
Esta tese apresenta a proposta de uma arquitetura de Processamento Distribuído Aberto para Aplicações em um Escritório Móvel Convergente (EMC). O EMC é um dispositivo móvel portátil que disponibiliza os serviços de escritório com acesso a uma base de dados e com comunicação sem fio. O termo Convergente refere-se à convergência das tecnologias de Internet, telefonia móvel e televisão com transmissão digital, disponíveis em um único dispositivo móvel. A arquitetura de sistema proposta é baseada no Modelo de Referência de Processamento Distribuído Aberto (RMODP - Reference Model Open Distributed Processing) e pode ser implementada em objetos distribuídos. Como uma possível aplicação do sistema é apresentado um Escritório Móvel Convergente para o trabalho do arqueólogo em um sítio arqueológico.This thesis presents the proposal for an Open Distributed Processing Architecture for Applications in a Convergent Mobile Office (EMC). The EMC is a mobile portable device that makes available the office services, with access to databases and also wireless communication. The word Convergent refers to the convergence of the technologies of Internet, mobile telephony and digital television, available in a single mobile device. The system architecture proposed is based on the Reference Model of Open Distributed Processing (RMODP) and it can be implemented in distributed objects. As a possible application of the system is presented a Convergent Mobile Office for the archeologist\'s work in an archeological site.
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Shi, Shuai. "The convergence of geo-space and network space in city region development in China : taking the Mid-Yangtze River city region as an example." Thesis, University of Reading, 2018. http://centaur.reading.ac.uk/77846/.
Анотація:
This thesis is an empirical examination of the spatial mechanisms of city region development in China taking the Mid-Yangtze River (MYR) city region as an example, and investigating in particular, how spatial mechanisms are affected by the relationships between spatial factors and network capital. Conventional city region theory assumes that regional development is spatially homogeneous across spatial units and determined by indigenous factors. By using GIS techniques, Social Network Analysis (SNA) and Spatial Econometric Modelling on data from the National Bureau of Statistics of China (NBS), the Zephyr database, and the State Intellectual Property Office of China (SIPO), this thesis challenges that assumption. Chapter 2 outlines the interaction between cities and world economy change. Chapter 3 focuses on urban and regional change in the context of globalisation specifically, showing the importance of the city region in a new global economic context. Chapter 4 advances a spatial framework to investigate city region development, while Chapter 5 advances a network framework to investigate city region development, which builds two main research frameworks for the thesis. The next three chapters represent the main empirical contribution of this thesis. In terms of spatial patterns, Chapter 6 shows that the MYR city region is characterised by coexisting spatial associations and heterogeneity. Chapter 7 calculates the network capital that is embedded in cities’ strategic positions across territories. In terms of underlying driving mechanisms, Chapter 8 demonstrates that city region development is affected by the simultaneity of spatial spillovers based on geographic proximity and network capital based on strategic positions over spatial constraints. Chapter 9 discusses the main empirical findings and concludes by operationalising complexity theory as a means of understanding city region spatial driving mechanisms. Combining geo-space and network space mechanisms in analysis is found to have value for dissecting the complexity of city region development.
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Hammami, Ali. "La sécurité des futures architectures convergentes pour des services personnalisés : aspect architectural et protocolaire." Thesis, Paris, ENST, 2013. http://www.theses.fr/2013ENST0039/document.
Анотація:
L’émergence et l’évolution des réseaux de nouvelles génération (NGN) a soulevé plusieurs défis surtout en termes d’hétérogénéité, de mobilité et de sécurité. En effet, l’utilisateur est capable, dans un tel environnement, d’avoir accès à plusieurs réseaux, à travers différents terminaux, avec un choix vaste de services fournis par différents fournisseurs. De plus, les utilisateurs finaux demandent à être constamment connectés n’importe où, n’importe quand et n’importe comment. Ils désirent également avoir un accès sécurisé à leurs services à travers une session dynamique, seamless et continue selon leurs préférences et la QoS demandée. Dans ce contexte, la sécurité représente une composante majeure. Face à cette session user-centric sécurisée, plusieurs défis se posent. L’environnement est de plus en plus ouvert, de multiples services ne sont pas connus d’avance et nous avons une diversité de communications entre les services et les utilisateurs. L’hétérogénéité des ressources (terminaux, réseaux et services) impliquées dans la session de l’utilisateur accentue la complexité des tâches de sécurité. Les différentes déclinaisons de mobilité (mobilité de l’utilisateur, mobilité du terminal, mobilité du réseau et mobilité du service) modifient la session user-centric que l’on veut unique, sécurisée et seamless avec la délivrance d’un service continuThe emergence and evolution of Next Generation Networks (NGN) have raised several challenges mainly in terms of heterogeneity, mobility and security. In fact, the user is able, in such environment, to have access to many networks, via multiple devices, with a vast choice of services offered by different providers. Furthermore, end-users claim to be constantly connected anywhere, anytime and anyhow. Besides, they want to have a secure access to their services through a dynamic, seamless and continuous session according to their preferences and the desired QoS. In this context, security represents an important concern. In fact, this user-centric session should obviously be secured. However, many challenges arise. In such environment, system boundaries, which were well delimited, become increasingly open. Indeed, there are multiple services which are unknown in advance and multiple communications between services and with users. Besides, heterogeneity of involved resources (terminals, networks and services) in the user session increases the complexity of security tasks. In addition, the different types of mobility (user, terminal, network and service mobility) affect the user-centric session that should be unique, secure and seamless and ensure continuity of services
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Decoux, Benoît. "Un modèle connexionniste de vision 3-D : imagettes rétiniennes, convergence stéréoscopique, et apprentissage auto-supervisé de la fusion." Rouen, 1995. http://www.theses.fr/1995ROUES056.
Анотація:
Les études destinées à apporter l'apprentissage non-supervisé à la vision stéréoscopique artificielle s'inscrivent dans la recherche en auto-organisation des systèmes, et constituent une avancée dans la modélisation de la vision stéréo naturelle. Le principal objectif de cette thèse est de participer à cette recherche. Après quelques données sur la vision naturelle, des propriétés importantes des réseaux neuronaux sont présentées. L'accent est mis ensuite sur les propriétés d'auto-organisation de ces derniers, ainsi que sur leurs capacités sensorimotrices. Un passage en revue non-exhaustif des modèles connexionnistes de vision stéréo existant, est alors effectué. Enfin, un modèle connexionniste de vision stéréo est proposé. Ce modèle comporte deux processus complémentaires : 1) la convergence stéréo met en correspondance des régions, par minimisation d'une disparité globale. Elle simule un processus de convergence visio-motrice; 2) la fusion stéréo recherche alors la correspondance entre des éléments caractéristiques. La fusion est obtenue après une phase d'apprentissage auto-supervisé. Le type de l'apprentissage est ainsi dénommé parce que la règle utilisée est une règle d'apprentissage supervisé, mais dans laquelle l'information de supervision est extraite automatiquement des entrées visuelles par le modèle. Les scènes visuelles sont perçues au moyen d'un ensemble d'imagettes rétiniennes : il s'agit de petites images de différents champs visuels et résolutions.
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Norgren, Axel, and Martin Olsson. "Institutional Dynamics in the Global FDI Network : Examining The Co-evolution of Institutions and FDI with Stochastic Actor-Oriented Modelling." Thesis, Linköpings universitet, Nationalekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176549.
Анотація:
This thesis addresses the relationship between institutions and foreign direct investments (FDI). While the issue of how institutions attract FDI (selection) is quite well-researched, the empirical evidence for institutions spreading through FDI (influence) is more ambiguous. We argue that past studies have neglected issues of endogeneity and interdependence in their modelling. We amend these issues by using a Stochastic Actor-Oriented network model which allows for interdependent and endogenous processes. The thesis also addresses the mechanisms governing the general relation between FDI and institutions and what these can tell us about institutional change and the process of globalisation. The model provides no evidence that FDI helps to spread institutions from home to host countries, but it does provide evidence that the selection effect can be an important dynamic between FDI and a certain set of institutions. Finally, we argue that FDI does not seem to be a contributory factor to institutional convergence.
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Hrustic, Edina, and Maria Iverbo. "Facebook - En virtuell mötesplats och en skvallergrotta : En kvalitativ studie om Facebooks betydelse för ungdomar." Thesis, University of Kalmar, School of Communication and Design, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-2751.
Анотація:
Authors: Edina Hrustic & Maria Iverbo Title: Facebook – a virtual meetingplace and a gossipcave Level: BA Thesis in Journalism Location: Linnaeus University Language: Swedish Number of pages: 72
Abstract
The aim of our study was to examine the meaning of the social media Facebook for young people who are in the age of 16 to 25 years. We wanted to gain an understanding in the youths´ thoughts and beliefs of how Facebook exists and plays a role in their lives. As a result from this research, we discussed how social media might affect the future of journalism.
We formed our thesis based on research of the digital network society, social networks, the youth culture, and how the target group; the young people use and experience social media. We made a questionnaire for 36 high school students, and three of these participated in a focusgroup-discussion. We combined and analyzed the response from the questionnaire and the focus group in our final result, and discussed patterns and relations between the youngsters´ answers.
Our result shows that Facebook mostly is regarded to be a virtual meetingplace, where these young people can interact and communicate with each other. They mostly communicate with their friends from the real-life, and youths´ use Facebook as a tool when they want to find out what people in their surrounding do. The questionnaire result also shows that Facebook can be seen as an information channel, where the young people can get gossip and offer each other invitations to common events.
From this study, we can point out that the social network is practically of great importance in young peoples’ lives. The questionnaire of Facebook and how young people´s habits are affected implies that it is important to use the social network discussion while analysing the convergence between so called; "old" and "new media". Young people steer and direct the use of media, and that is the reason why the understanding about their thoughts of social media is significantly important. One could practically say that youngsters can affect the future of journalism, and the design and development of media.
Key words: young people, Facebook, social media, virtual communication, the convergence of media, digital network society, journalism
30
Kong, Seunghyun. "Linear programming algorithms using least-squares method." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-04012007-010244/.
Анотація:
Thesis (Ph. D.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2007.Martin Savelsbergh, Committee Member ; Joel Sokol, Committee Member ; Earl Barnes, Committee Co-Chair ; Ellis L. Johnson, Committee Chair ; Prasad Tetali, Committee Member.
31
Garayev, Vener. "The impact of organizational goal convergence, information-communication technology utilization, and inter-organizational trust on network formation and sustainability the case of emergency management in the United States." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4899.
Анотація:
With the increase of severity and scope of disasters, collaborative networks have become the main tool to tackle with complex emergencies. Networks, however, are mostly effective to the extent they are maintained over time. This study analyzes whether organizational goal convergence, information-communication technology utilization, and inter-organizational trust impacts network sustainability. The main research questions of the study are: (1) How are organizational goals, technical/technological capacity of organizations, and trust among organizations of a network are related to the sustainability of collaborative network relationships? (2) Which of the above-mentioned factors plays the most significant role in affecting network sustainability? Covering the context of emergency management system in the United States, this study utilized a self-administered survey that was electronically distributed to county emergency managers across the country. The data consisting of 534 complete responses was analyzed in Statistical Package for the Social Sciences (SPSS) Inc. software's PASW (Predictive Analytics SoftWare) Statistics version 18.0 and transferred to Amos 18.0 software for structural equation modeling (SEM) analysis. The findings suggest that organizational goal convergence, information-communication technology utilization, and inter-organizational trust have positive and statistically significant relationships with network sustainability; and, inter-organizational trust is the strongest factor followed by information-communication technology utilization and organizational goal convergence. The study contributes to the literature on network sustainability with specific suggestions for emergency management practitioners.ID: 030422705; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 168-183).
Ph.D.
Doctorate
Public Affairs
Health and Public Affairs
32
Nassar, Rachad. "Une architecture convergente pour une continuité et personnalisation de services : aspects architectural et fonctionnel." Thesis, Paris, ENST, 2012. http://www.theses.fr/2012ENST0025/document.
Анотація:
De nos jours, l'avènement de la dérégulation et l'ouverture à la concurrence stimulent les fournisseurs de services à être de plus en plus compétitifs et à attirer de plus en plus d'abonnés afin de faire face aux fortes pressions du marché. Pour ce faire, les fournisseurs d'aujourd'hui favorisent une approche user-centric qui consiste à fournir le plus rapidement possible des services orientés utilisateurs. Cette approche user-centric gagne de plus en plus d'ampleur suite à l'émergence du contexte de nouvelle génération de réseaux et de services (NGN/NGS). Dans ce contexte où les convergences de réseaux et de services sont omniprésentes, l'utilisateur devient de plus en plus nomade et il réclame l'accès à n'importe quel service, n'importe où, n'importe quand et par n'importe quel moyen. Son but est de composer dynamiquement une session personnalisée de services, dans laquelle converge un ensemble de services multi-domaines (Telco, Web et IT). Ensuite, il désire maintenir la continuité de cette session de services tout au long de sa mobilité spatiale et temporelle. Dans le cadre de cette thèse, nous proposons une nouvelle architecture de services, dénommée NGN/NGS Middleware qui suit une approche horizontale distribuée évènementielle et orientée service, et qui s'appuie sur un nouveau modèle de services. De plus, nous proposons deux solutions de gestion de la continuité de services, basées sur des communautés virtuelles et sur un handover sémantique. Ces solutions tiennent compte des préférences de l'utilisateur ainsi que de son contexte ambiant. Enfin, nous pensons apporter une réponse au monde du cloud en intégrant nos solutions pour gérer les utilisateurs du cloudNowadays, with the advent of deregulation, service providers aim to be more competitive and to attract more subscribers in order to cope with the high market pressure. For this purpose, today's providers support a user-centric approach that consists on quickly providing user oriented services. This user-centric approach becomes more and more significant with the emergence of the next generation networks and services (NGN/NGS) context. Within this context, where network convergence and service convergence are omnipresent, the end-user becomes more nomadic and claims the access to any service, anywhere, anytime and by any means. His goal is to dynamically compose a personalized service session while converging a set of multi-domain services (Telco, Web and IT). Then, he wants to maintain the continuity of this service session throughout his spatial and temporal mobility. Within the scope of this thesis, we propose a novel service architecture, namely the NGN/NGS Middleware, that adopts an horizontal distributed event-driven and service oriented approachn and that is based on a novel service model. In addition, we propose two solutions for service continuity management, that are based on virtual communities and on a semantic handover. These solutions take into consideration the user's preferences and ambiant context. At the end, we think we could answer some cloud computing challenges by integrating our solutions to manage cloud users
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Blum, Niklas. "Formalization of a converged internet and telecommunications service environment." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5114/.
Анотація:
The programmable network envisioned in the 1990s within standardization and
research for the Intelligent Network is currently coming into reality using IPbased Next Generation Networks (NGN) and applying Service-Oriented Architecture (SOA) principles for service creation, execution, and hosting. SOA is the foundation for both next-generation telecommunications and middleware architectures, which are rapidly converging on top of commodity transport services.
Services such as triple/quadruple play, multimedia messaging, and presence are enabled by the emerging service-oriented IPMultimedia Subsystem (IMS), and allow
telecommunications service providers to maintain, if not improve, their position in the marketplace. SOA becomes the de facto standard in next-generation middleware systems as the system model of choice to interconnect service consumers and providers within and between enterprises.
We leverage previous research activities in overlay networking technologies along with recent advances in network abstraction, service exposure, and service creation to develop a paradigm for a service environment providing converged Internet and Telecommunications services that we call Service Broker. Such a Service Broker provides mechanisms to combine and mediate between different service paradigms from the two domains Internet/WWW and telecommunications. Furthermore, it enables the composition of services across these domains and is capable of defining and applying temporal constraints during creation and execution time. By adding network-awareness into the service fabric, such a Service Broker may also act as a next generation network-to-service element allowing the composition of crossdomain and cross-layer network and service resources.
The contribution of this research is threefold: first, we analyze and classify principles and technologies from Information Technologies (IT) and telecommunications to identify and discuss issues allowing cross-domain composition in a converging service layer. Second, we discuss service composition methods allowing the creation of converged services on an abstract level; in particular, we present a formalized method for model-checking of such compositions. Finally, we propose a Service Broker architecture converging Internet and Telecom services. This environment enables cross-domain feature interaction in services through formalized obligation policies acting as constraints during service discovery, creation, and execution time.Das programmierbare Netz, das Ende des 20. Jahrhunderts in der Standardisierung und Forschung für das Intelligente Netz entworfen wurde, wird nun Realität in einem auf das Internet Protokoll basierendem Netz der nächsten Generation (Next Generation Network). Hierfür kommen Prinzipien aus der Informationstechnologie, insbesondere aus dem Bereich dienstorientierte Architekturen (Service-Oriented Architecture / SOA) für die Diensterstellung, -ausführung und -betrieb zum Tragen. SOA bietet hierbei die theoretische Grundlage für Telekommunikationsnetze, vor allem jedoch für die dazugehörigen Dienstplattformen. Diese erlauben dem Telekommunikationsbetreiber seine Position in einem offenen Marktplatz der Dienste auszubauen. Dazu bedarf es allerdings möglichst flexibler Dienstumgebungen, die die Kooperation zwischen Dienstanbietern und Nutzern aus unterschiedlichsten Domänen durch Unterstützung geeigneter Werkzeuge und Mechanismen fördert. Im Rahmen dieser Dissertation definieren wir aufbauend auf Forschungsergebnisse im Bereich Overlay-Netze, Netzabstraktion und Zugriff auf exponierte Dienste eine Service Broker genannte Dienstumgebung für konvergente Internet- und Telekommunikationsdienste. Dieser Service Broker stellt Mechanismen für die Komposition von Diensten und Mediation zwischen unterschiedlichen Dienstparadigmen und Domänenspezifika beim Dienstaufruf zur Verfügung. Der Forschungsbeitrag dieser Arbeit findet auf unterschiedlichen Ebenen statt: Aufbauend auf einer Analyse und Klassifikation von Technologien und Paradigmen aus den Bereichen Informationstechnologie (IT) und Telekommunikation diskutieren wir die Problemstellung der Kooperation von Diensten und deren Komposition über Domänengrenzen hinweg. In einem zweiten Schritt diskutieren wir Methoden der Dienstkomposition und präsentieren eine formalisierte Methode der modellbasierten Diensterstellung. Der Schwerpunkt der Arbeit liegt auf der Spezifikation der Service Broker Dienstumgebung und einem zugrundeliegenden Informations- und Datenmodell. Diese Architektur erlaubt die Komposition und Kooperation von Diensten über Domänengrenzen hinweg, um konvergente Internet- und Telekommunikationsdienste zu realisieren. Hierfür wird ein auf Obligationspolitiken basierendes Regelsystemformalisiert, das Interaktionen zwischen Dienstmerkmalen während der Diensterstellung und -ausführung definiert.
34
Vrablic, Pavol. "Simulace SDN sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-317006.
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Aslam, Waqas. "An Empirical Study to Observe Route Recoverability Performance of Routing Protocols in Real-Time Communication." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2390.
Анотація:
This thesis is an experimental study to evaluate the performance of different routing protocols in commonly deployed scenarios. This study mainly focuses on how much time each protocol consumes while recovering from a link-loss. It provides a guide line for the best routing solutions for ISPs, individual organizations or other types of providers which are engaged in providing reliable real-time communications to their subscribers. Such communications may include vehicle trafficking data, online TV programs (IPTV), voice over IP telephony (VoIP), weather forecasts, tracking systems and many other services which totally depend upon the reliability of real-time data streams, where any major loss in received data may bring significant negative results in the integrity of the entire application.
This work experimentally observes and tracks the loss of UDP packets when changes in the network topology occur. In order to make this observation in real network topologies, a custom-designed software tool has been developed. The tool is capable of delivering enough resources to a tester in evaluating the performance of routing protocols. All the test results derived from the software tool are statistically evaluated and on the basis of the outcome a better proposition can be provided to network administrators which face inconsistent topological issues.
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Aura, Heikki. "The new logic of value creation." Thesis, Linköping University, Department of Management and Economics, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-700.
Анотація:
The understanding of value is often described in terms of an industrial view in which value creation is linear, additive process. The emerging view takes a different approach to value creation: it’s interactive, relationships-based and synchronic. But either of these views capture fully the value creating importance of elements present especially in converging industries: coopetition, networks and external relationships. This thesis has been conducted by gathering primary data from telecommunication industry companies in forms of interviews. The studied companies are engaged in numerous different kinds of external relationships and they are viewed as strategically important. Additionally, respondents believed that their companieswere part of a network but no clear illustration of it could be given. For the purpose of describing some of the complexity present, the value network -framework has been developed.
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Tilson, David Albert. "The Interrelationships between Technical Standards and Industry Structures: Actor-Network Based Case Studies of the Mobile Wireless and Television Industries in the US and the UK." online version, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=case1207164101.
Анотація:
Thesis (Ph. D.)--Case Western Reserve University, 2008.Department of Information Systems, Weatherhead School of Management. Includes bibliographical references. Available online via OhioLINK's ETD Center.
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Pérez, Costa Xavier. "Toward All-IP networks : IP and wireless networks convergence." Doctoral thesis, Universitat Politècnica de Catalunya, 2005. http://hdl.handle.net/10803/7051.
Анотація:
In this thesis the state of the art for IP networks and the two most predominant wireless access networks, UMTS and Wireless LANs, has been reviewed with respect to the enhancements required toward the objective of supporting services across different network technologies in a seamless manner. Three main areas of research were identified as key in the path toward All-IP networks: i) IP-based mobility management, ii) IP-based UMTS Radio Access Networks and iii) QoS for Wireless LANs.Future All-IP networks require of an IP-based mobility management protocol to support mobility across heterogeneous networks. Several protocols are being proposed in the IETF for this purpose with Mobile IPv6, Hierarchical Mobile IPv6 and Fast Handovers for Mobile IPv6 being the ones with a higher acceptance. Our contribution in this area has been the thorough study of the performance enhancements provided by each protocol and their associated costs in realistic scenarios to support the design process of Mobile IPv6-based networks where the suitability of the different options has to be evaluated. In addition, we proposed a combination of Hierarchical Mobile IPv6 and Fast Handovers for Mobile IPv6, based on the description provided in the Hierarchical Mobile IPv6 draft, that aims to outperform both proposals by adding the advantages of each of them.
During the evaluation of the IP-based mobility management protocols, the mobility model influence over the performance results led to an additional line of study where the main characteristics of the Random Waypoint mobility model were analyzed. The random waypoint model is a commonly used mobility model for simulations of wireless communication networks. We gave a formal description of this model in terms of a discrete- time stochastic process which provides a deep understanding on the characteristics of the mobility created by its usage. The results of our work are of practical value for performance analysis of communication networks to avoid misinterpretation of simulation results.
UMTS networks being deployed today based on the Release'99 specifications use ATM transport in the Radio Access Network (RAN). The specifications for future releases include options to support IP transport in the RAN, however, several challenges are introduced with regard to a significant increase in the transport protocol overhead and the provision of QoS guarantees. These challenges have to be addressed to ensure an efficient usage of the scarce RAN resources. Our work focused first in reducing the resources needed in the air interface for the expected most relevant application in future 3G networks, Voice over IP (VoIP). We designed a radio access bearer for VoIP when Robust Header Compression (RoHC) is used that reduces in about 50% the resources required in the air interface. Then, a multiplexing scheme for the reduction of the overhead in the wired part of the RAN that allows QoS differentiated scheduling was described and evaluated. The results showed an increase in the efficiency of the RAN resources usage between 100% and 260%, in our scenarios, when combined with RoHC. Finally, we proposed and evaluated a QoS differentiated scheduling mechanism based on Earliest-Deadline-First that fulfills the RAN specific synchronization requirements while providing the QoS differentiation required by the applications.
The IEEE 802.11 standard presents relevant defficiencies in order to support applications with QoS requirements. The integration of the Wireless LAN technology in future All-IP networks heavily depends on the success of the upcoming 802.11e standard which extends the 802.11MAC layer to provide QoS guarantees. With our work in this area we contributed to the 802.11e research standardization effort and designed three extensions of the 802.11 MAC layer to provide delay guarantees (DIME-EF) and bandwidth guarantees, absolute (ARME) or relative (DWFQ).
Moreover, we analyzed the implications of introducing Wireless LAN capabilities in battery limited mobile devices as for example cellular phones. Based on the significant impact observed of the 802.11 power save mode over the 802.11e QoS mechanisms we designed and evaluated a solution that provides a soft upper bound of the data frames downlink delay according to the downlink frame interarrival time while minimizing the battery consumption. Part of this work has been used for the design and configuration of the NEC 3G/WLAN mobile terminal N900iL.
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Gianoto, Antonio Carlos. "O processo de migração de sistemas corporativos de comunicação TDM para plataformas convergentes IP com preservação de ativos." Universidade Presbiteriana Mackenzie, 2006. http://tede.mackenzie.br/jspui/handle/tede/2749.
Анотація:
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Previous issue date: 2006-06-29Fundo Mackenzie de Pesquisa
The aim of this elaboration is to present a study of the migration process involved transforming the digital PBX (Private Branch Exchange), TDM (Time Division Multiplex), SPC (Stored Program Control) based platforms of corporate communications on technology to converged IP (Internet Protocol) systems supported by the TCP/IP (Transmission Control Protocol/Internet Protocol) protocol. This proposal analyzes the necessary interventions in order to preserve the investments made in these platforms, integrating them to existent data networks. Beside other benefits presented in this work, one key advantage is the possibility to transport voice over an existing data infrastructure, optimizing usage of carrier connections.
O objetivo desta dissertação é o de apresentar um estudo do processo de migração de plataformas de voz PABX (Private Automatic Branch Exchange) TDM (Time Division Multiplex) de comunicações corporativas baseadas na tecnologia CPA-T (Controle por Programa Armazenado estágio de comutação temporal digital), para sistemas convergentes suportados pelo protocolo TCP/IP (Transmission Control Protocol/Internet Protocol). São analisadas as intervenções necessárias para esta migração, preservando ao máximo os investimentos efetuados nestas plataformas, integrando-as as redes de dados existentes. Dentre outras vantagens apresentadas no texto, destaca-se a otimização dos acessos fornecidos pelas operadoras de telecomunicações pelo compartilhamento da infra-estrutura da rede de dados para o tráfego de sinais de voz.
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Treadgold, Nicholas K. Computer Science & Engineering Faculty of Engineering UNSW. "Constructive neural networks : generalisation, convergence and architectures." Awarded by:University of New South Wales. School of Computer Science and Engineering, 1999. http://handle.unsw.edu.au/1959.4/17615.
Анотація:
Feedforward neural networks trained via supervised learning have proven to be successful in the field of pattern recognition. The most important feature of a pattern recognition technique is its ability to successfully classify future data. This is known as generalisation. A more practical aspect of pattern recognition methods is how quickly they can be trained and how reliably a good solution is found. Feedforward neural networks have been shown to provide good generali- sation on a variety of problems. A number of training techniques also exist that provide fast convergence. Two problems often addressed within the field of feedforward neural networks are how to improve thegeneralisation and convergence of these pattern recognition techniques. These two problems are addressed in this thesis through the frame- work of constructive neural network algorithms. Constructive neural networks are a type of feedforward neural network in which the network architecture is built during the training process. The type of architecture built can affect both generalisation and convergence speed. Convergence speed and reliability areimportant properties of feedforward neu- ral networks. These properties are studied by examining different training al- gorithms and the effect of using a constructive process. A new gradient based training algorithm, SARPROP, is introduced. This algorithm addresses the problems of poor convergence speed and reliability when using a gradient based training method. SARPROP is shown to increase both convergence speed and the chance of convergence to a good solution. This is achieved through the combination of gradient based and Simulated Annealing methods. The convergence properties of various constructive algorithms are examined through a series of empirical studies. The results of these studies demonstrate that the cascade architecture allows for faster, more reliable convergence using a gradient based method than a single layer architecture with a comparable num- ber of weights. It is shown that constructive algorithms that bias the search direction of the gradient based training algorithm for the newly added hidden neurons, produce smaller networks and more rapid convergence. A constructive algorithm using search direction biasing is shown to converge to solutions with networks that are unreliable and ine??cient to train using a non-constructive gradient based algorithm. The technique of weight freezing is shown to result in larger architectures than those obtained from training the whole network. Improving the generalisation ability of constructive neural networks is an im- portant area of investigation. A series of empirical studies are performed to examine the effect of regularisation on generalisation in constructive cascade al- gorithms. It is found that the combination of early stopping and regularisation results in better generalisation than the use of early stopping alone. A cubic regularisation term that greatly penalises large weights is shown to be benefi- cial for generalisation in cascade networks. An adaptive method of setting the regularisation magnitude in constructive networks is introduced and is shown to produce generalisation results similar to those obtained with a fixed, user- optimised regularisation setting. This adaptive method also oftenresults in the construction of smaller networks for more complex problems. The insights obtained from the SARPROP algorithm and from the convergence and generalisation empirical studies are used to create a new constructive cascade algorithm, acasper. This algorithm is extensively benchmarked and is shown to obtain good generalisation results in comparison to a number of well-respected and successful neural network algorithms. A technique of incorporating the validation data into the training set after network construction is introduced and is shown to generally result in similar or improved generalisation. The di??culties of implementing a cascade architecture in VLSI are described and results are given on the effect of the cascade architecture on such attributes as weight growth, fan-in, network depth, and propagation delay. Two variants of the cascade architecture are proposed. These new architectures are shown to produce similar generalisation results to the cascade architecture, while also addressing the problems of VLSI implementation of cascade networks.
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Tinoco, López César Adair. "Podcasting the brand Sweden : How Radio Sweden International appropriates the logics of Nation Branding to present its information in a convergent, globalizing and networked society." Thesis, Uppsala universitet, Medier och kommunikation, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-225270.
Анотація:
The advent and massification of the ICTs and the widespread use of internet have transformed the way in which traditional media such as ratio and television communicate with the audience, not only because of the technological shift itself, but because of the convergence culture undergoing as a result of the new relationships taking place online. Particularly, we wonder how the news’ organizations based in traditional media are adapting to these changes. Our assumption is that, although the news’ organizations have understood and are currently using the online technologies to present their information in varied ways with the intention to reach a broader audience and to generate higher levels of engagement, still much needs to be analyzed on how the contents are handled through each particular online platform. Along this study, we propose to introduce the rationale of Nation Branding from a Cultural/Critical perspective as a tool to analyze how transnational news organizations present their contents, since, even when their purpose might not be to carry out directly a Nation Branding strategy, they might be falling into the use of certain features of the Nation Branding logics. In order to perform this analysis, we explore, from a reductionist approach, the ways in which the English section of Radio Sweden International (a branch of Sveriges Radio, the public radio service in Sweden) has developed its online strategy, trying to identify: 1) whether Radio Sweden International is appropriating the logics of Nation Branding in the way they present their information; 2) if the online strategy of Radio Sweden International is oriented (either directly or indirectly) to build and/or enhance the “Brand Sweden”; and 3) the ways in which Radio Sweden International uses each specific digital platform in its online strategy. We collected 1893 elements across the Twitter account (760), the news’ website (620), the podcasts (422), and the Facebook page (91) of Radio Sweden International, which were submitted to the classifications of the Nation Branding model known as “Anholt’s hexagon”. What we found was that, although 70.4% of the elements do fit within Anholt’s hexagon, 29.6% of the elements did not fit, these last elements corresponding to Domestic News and Self-Promotion of the organization, reason why a new classification of these elements was due, giving as a result 9 new categories of information different from Anholt’s model. As a result of our empirical study, we concluded that there are indeed similarities between the way in which Radio Sweden International presents its information, and the form in which the Cultural/Critical developing perspective of Nation Branding proposes how the nation communicates within the convergent, global and networked society. Although Radio Sweden International does not have the direct task of promoting the image of Sweden outside the country, the ways in which this organization presents its information and uses the different online platforms can be related to the way in which Nation Branding intends to construct the image of the country both, inside and outside Sweden.
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Horváth, Tomáš. "Optimalizace služeb v optických přístupových sítích FTTx." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-320777.
Анотація:
This thesis deals with an optimization of Triple play services and security in optical access networks. The first chapter provides theory basics which are necessary for results evaluation. The second chapter describes optical access networks with their parameters such as transmission speed, split ratio, line code, bit error rate etc. defined by ITU. Next chapter summaries the current state in optical networks construction field according to the European Union developing plan. The practical part of this thesis is divided into several subchapters. The significant part of the thesis is dedicated to the security of passive optical networks and design of proper security model for current networks. For this purpose, the unique parameter time propagation Tprop, with the novel security model was developed. Next part of the thesis provides an analysis of control traffic and data traffic in the gigabit passive optical networks. For a novel algorithm in activation process in gigabit passive optical networks the measurement results were used. The novel algorithm decreases the total time needed for this process. The last but one subchapter deals with an ILP model for Triple Play services. The last subchapter contains the own implementation of the transmission converge layer in VPIphotonics simulation tool.
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Pazeto, Tatiana Annoni. "Escalonadores de tráfego para garantir QOS em redes convergentes e corporais = Traffic schedulers to guarantee the QOS in convergent and body networks." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261152.
Анотація:
Orientador: Shusaburo MotoyamaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: As redes atuais, baseadas em tecnologia IP, transportam uma variedade de trafegos, tais como voz, dados e videos (trafego multimidia) e sao denominadas de redes convergentes. Outras redes estao em desenvolvimento para aplicacoes especificas como Redes de Sensores Corporais Sem Fio (RSC). O problema de prover a qualidade de servico (QoS - Quality of Service) de cada tipo de trafego em redes convergentes e em RSC, e essencial, pois os trafegos exigem diferentes requisitos de qualidade. Um dos principais parametros para prover QoS nessas redes e o escalonador de trafegos. O objetivo principal desta tese e analisar e propor escalonadores de trafego para a rede convergente e para RSC. O escalonador de trafegos proporciona uma utilizacao mais equitativa da banda disponivel. Como a rede baseada em IP foi originalmente projetada para transportar somente trafegos de dados, e estudada, nesta tese, a influencia do trafego multimidia no desempenho e no projeto do escalonador. O estudo e realizado atraves do desenvolvimento de varias plataformas de simulacoes que contem os varios tipos de trafegos, um buffer de armazenamento de pacotes, um link de saida e os varios tipos de escalonamento. Como o escalonador FIFO foi e continua sendo o mais utilizado, esse escalonador foi tomado como referencia para confrontar os resultados obtidos com o escalonador DRR e com o outro modelo inedito de escalonamento que usa em seu calculo de distribuicao de quotas, o conceito de banda efetiva. O escalonador DRR e o de banda efetiva podem fazer distincao entre os trafegos, de modo que a alocacao de bandas entre os varios trafegos se torne mais justa e atenda aos requisitos de QoS. Pelos resultados obtidos, pode-se constatar que a solucao de escalonamento proposta consegue controlar a perda de pacotes, mas o atraso deve ser melhor investigado. Alem disso, o escalonador DRR e mais indicado para trafego multimidia se comparado ao escalonador FIFO. Na maioria das propostas examinadas na literatura, o escalonador mais utilizado para RSC e aquele baseado em tecnica TDM. Existem poucos estudos em que o escalonador e baseado em servico ciclico, conhecido na literatura como polling. Nesta tese, estuda-se a conveniencia da utilizacao do escalonador baseado em polling para RSC. O estudo e, tambem, realizado atraves de uma plataforma de simulacoes que contempla fontes apropriadas desenvolvidas para sensores corporais, o escalonador polling e um buffer. As fontes desenvolvidas sao ineditas na literatura. Os resultados mostram que o escalonador polling pode ser uma boa alternativa para coletar dados dos sensores sobre ou subcutaneos implantados no corpo humano
Abstract: Today's networks are based on IP technology and carry a variety of traffic, such as voice, data and video (multimedia traffic) and are called convergent networks. Other networks are being developed for specific applications such as Wireless Body Sensor Networks (WBSN). The problem of providing Quality of Service (QoS) of each type of traffic in convergent networks and WBSN is essential, since the traffics demand different quality requirements. One of the main providers of QoS in these networks is the traffic scheduler. The main objective of this thesis is to analyze and propose traffic schedulers for convergent network and WBSN. The traffic scheduler provides a fairer use of the available bandwidth. As IP based network was originally designed to carry only data traffic, it is studied in this thesis, the influence of multimedia traffic on the performance and design of the scheduler. The study is carried out by developing multiple simulation platforms that contain various types of traffics, a buffer for packet storing, an output link and the various types of scheduling. As the FIFO scheduler was and remains the most widely used, it was taken as a reference to compare the results obtained with the DRR scheduler and with another unprecedented model of scheduling that uses in its calculation of the distribution of quotas, the concept of effective bandwidth. The DRR and the effective bandwidth schedulers can separate the traffics, so the allocation of bandwidths among the various traffics becomes fair and requirements of QoS can be met. From the results, it can be seen that the proposed scheduling solution can control packet loss, but the delay should be better investigated. Moreover, the DRR scheduler is best suited for multimedia traffic compared to the FIFO scheduler. In most of the proposals examined in the literature, the scheduler most used on WBSN is based on TDM technique. There are few studies in which the scheduler is based on cyclic service, known in the literature as polling. In this thesis, the convenience of using the scheduler based on polling for WBSN is studied. The study is also undertaken through a platform of simulations that include appropriate fonts developed for body sensors, the polling scheduler and a buffer. The sources developed are unprecedented in literature. The results show that the polling scheduler can be a good alternative to collect data from sensors implanted in subcutaneous or on the human body
Doutorado
Telecomunicações e Telemática
Doutora em Engenharia Elétrica
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Cao, Xun. "Convergence, divergence, and networks in international political economy /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10793.
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Hedlin, Ludwig. "Convergence of Linear Neural Networks to Global Minimizers." Thesis, KTH, Matematik (Inst.), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281982.
Анотація:
It is known that gradient flow in linear neural networks using Euclidean loss almost always avoids critical points that have at least one eigendirection with negative curvature. Using algebraic invariants of the gradient flow we try to prove that the set of all critical points with no second-order curvature (zero Hessian) for arbitrary networks is associated to a subset of the invariants of lower dimension. This would mean that these critical points are almost surely avoided. We show that this holds for networks with $3$ or less hidden layers and a few other special cases. We show by way of explicit counter-example that it is not true for general deep networks.Det är känt att linjära neurala nätverk med Euklidisk loss-funktion under gradient flow alltid undviker kritiska punkter som har minst en egenriktning med negativ böjning. Med hjälp av algebraiska invarianter till gradient flow försöker vi bevisa att invarianter associerade med kritiska punkter med försvinnande Hessian-matris utgör en algebraisk mängd av lägre dimension. Det skulle innebära att dessa kritiska punkter nästan alltid undviks. Vi visar att för nätverk med $3$ eller färre gömda lager så gäller detta. Vi visar även med explicit motexempel att våran förmodan inte gäller för allmänna djupa nätverk.
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Wu, Yijun. "User-centric session et QoS dynamique pour une approche intégrée du NGN." Phd thesis, Télécom ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00579469.
Анотація:
La capacité à assurer la mobilité sans couture avec une E2E QoS sera capitale pour la réussite du NGN (Next Generation Network). Pour ce faire, les verrous à lever que nous avons relevés dans cette thèse se positionnent à l'interconnexion de trois domaines, à savoir : les mobilités, l'hétérogénéité et les préférences utilisateur. Notre première proposition d'ordres organisationnel et fonctionnel, pour laquelle nous préconisons la convergence des trois plans (user, contrôle et gestion) et les fonctionnalités associées. Ainsi nous obtenons une QoS dynamique pour satisfaire l'approche orientée "User-Centric ". Afin de mettre en œuvre la E2E QoS incluant la personnalisation dans la session "User-Centric", nous avons proposé une "Signalisation dynamique d'E2E QoS", qui est d'ordre protocolaire, sur le niveau de service afin de parvenir à la fourniture des services demandés par l'user et de se conformer au SLA. Pour couvrir tout impact de mobilité, nous avons ensuite proposé un " cross layer E2E Session Binding" au sein de notre architecture à quatre niveaux de visibilité (Equipement, Réseau, Service et User). Par le binding nous assurons la cohérence des informations entre les quatre niveaux de visibilité. Au-delà du binding, notre contribution sur la dimension informationnelle a porté sur les profils impliqués dans chaque étape du cycle de vie du service incluant les critères de QoS, les quels fournissent une image générique des composants du système de l'utilisateur et de toutes les ressources ambiantes. Finalement, nous montrons la faisabilité de nos contributions à travers des expérimentations sur notre plate-forme.
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Ameli, Mostafa. "Heuristic Methods for Calculating Dynamic Traffic Assignment Simulation-based dynamic traffic assignment: meta-heuristic solution methods with parallel computing Non-unicity of day-to-day multimodal user equilibrium: the network design history effect Improving traffic network performance with road banning strategy: a simulation approach comparing user equilibrium and system optimum." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSET009.
Анотація:
Les systèmes de transport sont caractérisés de manière dynamique non seulement par des interactions non linéaires entre les différents composants, mais également par des boucles de rétroaction entre l'état du réseau et les décisions des utilisateurs. En particulier, la congestion du réseau impacte à la fois la répartition de la demande locale en modifiant les choix d’itinéraire et la demande multimodale globale. Selon les conditions du réseau, ils peuvent décider de changer, par exemple, leur mode de transport. Plusieurs équilibres peuvent être définis pour les systèmes de transport. L'équilibre de l'utilisateur correspond à la situation dans laquelle chaque utilisateur est autorisé à se comporter de manière égoïste et à minimiser ses propres frais de déplacement. L'optimum du système correspond à une situation où le coût total du transport de tous les utilisateurs est minimal. Dans ce contexte, l’étude vise à calculer les modèles de flux d'itinéraires dans un réseau prenant en compte différentes conditions d’équilibre et à étudier l’équilibre du réseau dans un contexte dynamique. L'étude se concentre sur des modèles de trafic capables de représenter une dynamique du trafic urbain à grande échelle. Trois sujets principaux sont abordés. Premièrement, des méthodes heuristiques et méta-heuristiques rapides sont développées pour déterminer les équilibres avec différents types de trafic. Deuxièmement, l'existence et l'unicité des équilibres d'utilisateurs sont étudiées. Lorsqu'il n'y a pas d'unicité, la relation entre des équilibres multiples est examinée. De plus, l'impact de l'historique du réseau est analysé. Troisièmement, une nouvelle approche est développée pour analyser l’équilibre du réseau en fonction du niveau de la demande. Cette approche compare les optima des utilisateurs et du système et vise à concevoir des stratégies de contrôle afin de déplacer la situation d'équilibre de l'utilisateur vers l'optimum du systèmeTransport systems are dynamically characterized not only by nonlinear interactions between the different components but also by feedback loops between the state of the network and the decisions of users. In particular, network congestion affects both the distribution of local demand by modifying route choices and overall multimodal demand. Depending on the conditions of the network, they may decide to change for example their transportation mode. Several equilibria can be defined for transportation systems. The user equilibrium corresponds to the situation where each user is allowed to behave selfishly and to minimize his own travel costs. The system optimum corresponds to a situation where the total transport cost of all the users is minimum. In this context, the study aims to calculate route flow patterns in a network considering different equilibrium conditions and study the network equilibrium in a dynamic setting. The study focuses on traffic models capable of representing large-scale urban traffic dynamics. Three main issues are addressed. First, fast heuristic and meta-heuristic methods are developed to determine equilibria with different types of traffic patterns. Secondly, the existence and uniqueness of user equilibria is studied. When there is no uniqueness, the relationship between multiple equilibria is examined. Moreover, the impact of network history is analyzed. Thirdly, a new approach is developed to analyze the network equilibrium as a function of the level of demand. This approach compares user and system optimums and aims to design control strategies in order to move the user equilibrium situation towards the system optimum
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Sánchez, González Luis. "Contribution to the cross-layer optimization of intra-cluster communication mechanisms in personal networks (Contribución a la optimización intercapa de los mecanismos de comunicación intra-cluster en redes personales)." Doctoral thesis, Universidad de Cantabria, 2009. http://hdl.handle.net/10803/10672.
Анотація:
En el futuro, los dispositivos digitales formarán parte del entorno en el que las personas se desenvuelvan, participarán en nuestros objetivos y necesidades y nos ayudarán a "hacer más haciendo menos". A través de los dispositivos portátiles o aquellos que estén embebidos a nuestro alrededor el usuario será capaz de interactuar con el futuro universo de servicios e infraestructuras ubicuas. El principal paradigma que se seguirá se basa en que este universo estará centrado en el usuario ya que éste demandará los servicios que más le convengan en cualquier momento y lugar, todo ello preservando nuestra privacidad y seguridad. Este nuevo concepto no sólo se aplica a un entorno de ocio sino que en el campo profesional las redes inalámbricas de próxima generación permitirán incrementar nuestra productividad, reduciendo el peso de tareas repetitivas, poniendo a nuestra disposición la información relevante en el momento adecuado y según sean las necesidades particulares del usuario en ese momento y permitiéndonos trabajar con otras personas independientemente de donde se encuentren. En particular, se intuye que las redes de próxima generación se diseñen de forma que aglutinen todos los servicios disponibles a través de los diferentes sistemas que existan de forma que las posibles deficiencias de alguno de ellos se vean compensadas por otro. Lo que se pretende conseguir es que el usuario pueda disfrutar en todo momento y lugar de los servicios que desee sin que ello suponga un esfuerzo.Este concepto implica diferentes retos tecnológicos y la integración de múltiples sistemas. Dentro de estos retos tecnológicos esta Tesis aborda los siguientes: soporte de la heterogeneidad en lo referente a las tecnologías de acceso radio que existen y que eventualmente aparecerán en el futuro y que coexistirán en un mismo terminal; desarrollo de técnicas de optimización basadas en la cooperación entre diferentes capas de la pila de protocolos; implementación de estrategias de selección de la red que mejor pueda soportar un determinado servicio ante la posibilidad de utilización de múltiples tecnologías de acceso; optimización del uso de recursos energéticos en las comunicaciones dentro de la red; protección de la privacidad y la seguridad de las comunicaciones personales del usuario.Desde el punto de vista de las aportaciones, en esta Tesis se ha contribuido mediante el diseño, implementación y validación de una serie de técnicas de optimización de las comunicaciones en redes de dispositivos móviles basadas en información intercapa. Para ello, se propone una arquitectura de protocolos novedosa que permite soportar la heterogeneidad en términos de tecnologías de acceso dentro del mismo terminal. El concepto de aislar las capas superiores de la pila de protocolos de las tecnologías de acceso subyacentes se consigue a través de una Capa de Convergencia Universal (UCL, en sus siglas en inglés). El diseño y la especificación esta arquitectura así como de los bloques funcionales que la componen son la primera contribución que se hace en esta Tesis. La UCL supone el marco en el que el resto de técnicas de optimización que se presentan han sido desarrolladas.Igualmente, se desarrollan una serie de técnicas basadas en optimización intercapa que permiten una gestión eficiente de los recursos disponibles así como una mejora en el uso de la energía. Finalmente, se implementan los mecanismos de autenticación y encriptación que permiten asegurar las comunicaciones dentro de la red. El diseño, implementación y validación de estos mecanismos supone la segunda contribución en esta Tesis. El empleo de técnicas de optimización basadas en información procedentes de diferentes capas de la pila de protocolos es la base de los dos mecanismos que se han propuesto. El primero de ellos se basa en la selección dinámica de la tecnología de acceso a utilizar para obtener un rendimiento óptimo del sistema. La segunda estrategia de optimización consiste en el uso simultáneo de varias tecnologías de acceso para conseguir una mejora en las prestaciones de la red. Aparte de la optimización en cuanto al rendimiento en términos de ancho de banda y calidad de servicio, se ha evaluado la mejora de la eficiencia energética conseguida gracias a las soluciones propuestas. Los resultados obtenidos permiten concluir que las propuestas realizadas en el marco de esta Tesis representan una optimización tanto en parámetros de calidad de servicio como en la eficiencia energética del sistema.El mayor avance respecto del estado del arte se centra en habilitar al usuario para que utilice de manera transparente, eficiente y segura los dispositivos que tiene a su alrededor independientemente de la heterogeneidad que presenten y sin requerir de un conocimiento intensivo de la tecnología. El usuario podrá comunicarse haciendo un uso óptimo de los recursos a su alcance sin preocuparse de tener que gestionarlos él mismo.In the future, computation will be human-centred: it will enter the human world, handling our goals and needs and helping us to do more by doing less. Next generation wireless systems should provide the user access with a broad range of services in a transparent way, independently of user location, by making the technology invisible and embedded in the natural surroundings. New systems will boost our productivity. They will help us automate repetitive human tasks, control a wide range of physical devices in our environment, find the information we need (when we need it, without obliging us to examine thousands of search-engine hits), and enable us to work together with other people through space and time.The achievement of this paradigm led to the identification of a set of optimizations in intra-cluster communications that were needed to fully support it. Firstly, heterogeneity will be a fundamental characteristic of next generation wireless communications since more and more personal devices are equipped with multiple network access technologies so that the user can have access to the different services that the different operational environments provide. However, Next Generation Networks (NGN) will comprise such a diverse number of possibilities that the users cannot be expected to take technical decisions on their own. It is necessary to provide mechanisms that intelligently select the optimal available access network based on context information such as user preferences, power consumption, link quality, etc. Finally, users need to trust the system that supports their personal communications. Within a personal network the most confidential information might be exchanged and the user need to be sure that this will never be disclosed. If the system fails in these features, NGN in general and PNs in particular will never happen.This Thesis has contributed with the development of the mechanisms that tackle the abovementioned challenges. The design and specification of a convergence framework, the so-called Universal Convergence Layer (UCL), has been the first topic addressed. This framework aims to manage all the network access interfaces with which a device is equipped so that they can be transparently used by upper layers as if the node were equipped with a single access technology. On the other hand, the UCL enables the cross-layer optimization paradigm. Its privileged location within the protocol stack gives the UCL the possibility to support both bottom-up and top-down information flow. In this sense, two different solutions based on cross-layer optimization have been proposed to enhance the performance and energy efficiency of the system. The first one deals with the selection at run-time of the most appropriate wireless interface to be used in order to improve the system performance. The second one leverages the striping concept in order to exploit all the network interfaces available. Finally, the UCL also plays a key role in security issues as an enabler for providing link-layer security mechanisms that ensure data confidentiality and integrity, authenticity and non-repudiation. The techniques implemented for node authentication combined with traffic encryption in ad-hoc networks have been thoroughly assessed and have demonstrated their appropriateness.The biggest advance in the state-of-the-art comes from enabling the user to have easy, affordable and seamless control of their devices over heterogeneous communications networks. They are empowered to communicate efficiently and securely with their selected interaction groups, no matter what kind of access is available for them to use.
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Paliwal, Gaurav. "Convergence : the next big step /." Online version of thesis, 2006. https://ritdml.rit.edu/dspace/handle/1850/1316.
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Sapozhnikov, Artyom Vasilyevich. "Existence of moments and convergence rates in stochastic networks." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/256.