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A Management Tool for the Replication of Operating Systems in Wireless Communication Networks

Crepaldi, Luis G.; Digiere, Adriano R.; Spolon, Roberta; Cavenaghi, Marcos A.; Lobato, Renata S.
Fonte: IEEE Computer Soc Publicador: IEEE Computer Soc
Tipo: Conferência ou Objeto de Conferência Formato: 86-92
Português
Relevância na Pesquisa
45.69%
To simplify computer management, various administration systems based on wired connections adopt advanced techniques to manage software configuration. Nevertheless, the strong relation between hardware and software makes for an individualism of that management, besides penalizing computational mobility and ubiquity. All these issues lead to degradation of scalability, flexibility and the facility to install and maintain distributed applications. This article presents an environment for centralized wireless communication network management, named WSE-OS (Wireless Sharing Environment - Operating Systems): a model based on Virtual Desktop Infrastructure (VDI) which associates virtualization techniques and safe remote access systems to create a distributed architecture as a base for a managing system. WSE-OS is capable of accomplishing the replication of operating system images using wireless communication network, besides offering abstraction of hardware to its clients, making the management more flexible and independent of wired connections. Results obtained from this work indicate that WSE-OS allows disseminating, through a single software configuration, the execution of data related to operating system images in client computers. WSE-OS can also be used as a management tool for operating systems in a wireless network.

Um mecanismo cognitivo para adaptação automática da taxa de transmissão em redes IEEE 802.11; A cognitive mechanism for automatic data rate adaptation in IEEE 802.11

Luciano Jerez Chaves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/06/2010 Português
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A utilização das redes sem fio vem se tornando cada vez mais frequente, e o IEEE 802.11 é o padrão escolhido pela maioria dos dispositivos. Com o objetivo de adaptar-se às condições instáveis dos canais de transmissão sem fio, este padrão especifica diversos esquemas de codificação e modulação de dados que devem ser, obrigatoriamente, implementados pelas interfaces sem fio. Como conseqüência, essas interfaces passam a suportar múltiplas taxas de transmissão, definidas em função da combinação entre a codificação e a modulação utilizada. Entretanto, não faz parte da especificação o processo para a escolha dinâmica de qual taxa de transmissão utilizar, deixando livre para os fabricantes a definição de um algoritmo para solucionar este problema, conhecido por adaptação automática da taxa de transmissão. Apesar de diversas soluções terem sido propostas na literatura, o desempenho alcançado por elas está limitado por fatores como a dificuldade na estimativa da qualidade do canal e o compartilhamento injusto dos recursos entre as estações da rede. Para lidar com estes desafios, este trabalho apresenta um mecanismo cognitivo para adaptação automática da taxa de transmissão denominado Cognitive Rate Adaptation (CORA). Este é um mecanismo completamente distribuído...

Aplicabilidade de Sistemas de Videoconferência sobre a Internet de Banda Larga para apoio ao Sistema bimodal de Ensino; The Applicability of Desktop Videoconferencing Systems over Broadband Networks to Support the b-learning Education System

Roth, Rogério
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Relatório
Português
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Esta pesquisa se propôs a investigar o estado actual da tecnologia de videoconferência baseada em computador; avaliou o potencial efectivo desta tecnologia para auxiliar na educação à distância no sistema bimodal (parte presencial e parte à distância) e buscou elementos para subsidiar a especificação de requisitos de comunicação de dados para apoiar aplicações que envolvam principalmente a utilização de áudio e vídeo em tempo real, sobre redes de banda larga.; This research investigated the current state of desktop videoconferencing technology; to evaluate the effective potential of this technology to aid in the distance education in the b-learning system (blended) and to seek elements to subsidize the specification of data communication s requirements to support applications that mainly involve real time audio and video utilization, over broadband networks.

Failsafe distributed optimal routing in data-communication networks

Fonte: Massachusetts Institute of Technology, Laboratory for Information and Decision Systems Publicador: Massachusetts Institute of Technology, Laboratory for Information and Decision Systems
Formato: 148 p.; application/pdf
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by M. Sidi, A. Segall.; Bibliography: p. 146-148.; Research supported by ARPA Contract N00014-75-C-1183, ONR Contract ONR-N)))14-77-C-0532.

A unified theory of flow control and routing in data communication networks

Golestaani, Seyyed Jamaaloddin
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 94 leaves; 5064620 bytes; 5064383 bytes; application/pdf; application/pdf
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by Seyyed Jamaaloddin Golestaani.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

The estimation of delay gradients for purposes of routing in data-communication networks.

Bello, Martin Glen
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 188 leaves; 14981634 bytes; 14981392 bytes; application/pdf; application/pdf
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Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography : leaf 188.

An approach to a defense data network for the Saudi Ministry of Defense and Aviation

Al-Najashi, Abdulrahman Abdullah
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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Approved for public release; distribution unlimited.; Computer and data communication networks have become an integral part of the modern military structure. The technology of its software and hardware change rapidly. As a result, it is of paramount importance for the Saudi Ministry of Defense and Aviation (MODA) to remain abreast of such technology. Due to lack of actual data about MODA requirements, this theme is focused on the general concepts of computer and data communications networks. In addition, this thesis includes a detailed discussion of the U.S. DDN in order to provide guidelines for MODA if similar network design is to be developed. The framework of network-capacity planning is briefly described as well.

Attacks against intrusion detection networks: evasion, reverse engineering and optimal countermeasures

Pastrana Portillo, Sergio
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
45.68%
Intrusion Detection Networks (IDNs) constitute a primary element in current cyberdefense systems. IDNs are composed of different nodes distributed among a network infrastructure, performing functions such as local detection --mostly by Intrusion Detection Systems (IDS) --, information sharing with other nodes in the IDN, and aggregation and correlation of data from different sources. Overall, they are able to detect distributed attacks taking place at large scale or in different parts of the network simultaneously. IDNs have become themselves target of advanced cyberattacks aimed at bypassing the security barrier they offer and thus gaining control of the protected system. In order to guarantee the security and privacy of the systems being protected and the IDN itself, it is required to design resilient architectures for IDNs capable of maintaining a minimum level of functionality even when certain IDN nodes are bypassed, compromised, or rendered unusable. Research in this field has traditionally focused on designing robust detection algorithms for IDS. However, almost no attention has been paid to analyzing the security of the overall IDN and designing robust architectures for them. This Thesis provides various contributions in the research of resilient IDNs grouped into two main blocks. The first two contributions analyze the security of current proposals for IDS nodes against specific attacks...

Stone Chips to Silicon Chips: A Grounded Theory of Information and Communication Technology adoption in Australian Indigenous households rural, urban and remote.

Radoll, Peter John
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
Português
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Information and Communication Technologies (ICTs) have become an everyday part of life. Communication networks within Australia link financial, educational, government and non-government services to Australian households. Both the 2001 and 2006 Australian Census data demonstrate that Indigenous Australians are 69% less likely to access the Internet at home than the rest of the Australian population. This study examines the factors affecting the adoption of Information and Communication Technologies in Australian Indigenous households and provides a plausible explanation as to why this gap exists. This study uses a multiple case study approach and draws on the Glaserian Grounded Theory Methodology to examine Indigenous household ICT adoption in a rural Indigenous community, an urban Indigenous community and a remote Indigenous community, to identify differences and commonalities of ICT adoption and non-adoption in diverse cultural and geographical locations across Australia. The theoretical lens draws on Pierre Bourdieu's theory of habitus to develop a practice perspective of household ICT adoption established through the habitus concepts of structures and agency or society and individual. The research establishes the existence of the Indigenous substantive field and postulates that new practices are formed with the intersection of the Indigenous field and external fields. Through the development of substantive fields this thesis develops a theoretical framework of Indigenous household ICT adoption. The findings suggest that a single model of ICT adoption can be applied to all Indigenous communities across Australia.The results could have considerable practical and policy significance.; Supervisor - Associate Professor Walter Fernandez; Yes

Fiber optic sensors and self-reference techniques for temperature measurements in different industrial sectors

Tapetado Moraleda, Alberto
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
Português
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45.65%
El objetivo de este trabajo se centra especialmente en el desarrollo de sensores de fibra óptica y técnicas de autoreferencia para la medida de la temperatura en diferentes entornos industriales. El primer objetivo de este trabajo consiste en el diseño y desarrollo de un sensor de fibra óptica de bajo coste para la medida de la temperatura en transformadores de potencia y aplicaciones biomédicas. En estas aplicaciones, el uso de sensores de temperatura tradicionales resulta inadecuado debido a la presencia de fuertes interferencias electromagnéticas que pueden perturbar la lectura de la temperatura. Uno de los requisitos fundamentales para diseñar un sensor de temperatura que pueda usarse en aplicaciones biomédicas es el uso de materiales biocompatibles en su fabricación. En este sentido, una configuración simple que permite cumplir con los requisitos mencionados anteriormente es la modulación por intensidad en fibras poliméricas. Este tipo de sensores basan la lectura de la temperatura en medir las variaciones de potencia óptica en función de los cambios de temperatura que se aplican sobre el sensor. En este contexto, el uso de la tecnología asociada con la fibra óptica de plástico ofrece ventajas competitivas frente a otros materiales...

Structural Routability of n-Pairs Information Networks

Nair, Girish N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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Information does not generally behave like a conservative fluid flow in communication networks with multiple sources and sinks. However, it is often conceptually and practically useful to be able to associate separate data streams with each source-sink pair, with only routing and no coding performed at the network nodes. This raises the question of whether there is a nontrivial class of network topologies for which achievability is always equivalent to routability, for any combination of source signals and positive channel capacities. This chapter considers possibly cyclic, directed, errorless networks with n source-sink pairs and mutually independent source signals. The concept of downward dominance is introduced and it is shown that, if the network topology is downward dominated, then the achievability of a given combination of source signals and channel capacities implies the existence of a feasible multicommodity flow.; Comment: The final publication is available at link.springer.com http://link.springer.com/chapter/10.1007/978-3-319-02150-8_7

Analyzing Linear Communication Networks using the Ribosome Flow Model

Zarai, Yoram; Mendel, Oz; Margaliot, Michael
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/08/2015 Português
Relevância na Pesquisa
45.69%
The Ribosome Flow Model (RFM) describes the unidirectional movement of interacting particles along a one-dimensional chain of sites. As a site becomes fuller, the effective entry rate into this site decreases. The RFM has been used to model and analyze mRNA translation, a biological process in which ribosomes (the particles) move along the mRNA molecule (the chain), and decode the genetic information into proteins. Here we propose the RFM as an analytical framework for modeling and analyzing linear communication networks. In this context, the moving particles are data-packets, the chain of sites is a one dimensional set of ordered buffers, and the decreasing entry rate to a fuller buffer represents a kind of decentralized backpressure flow control. For an RFM with homogeneous link capacities, we provide closed-form expressions for important network metrics including the throughput and end-to-end delay. We use these results to analyze the hop length and the transmission probability (in a contention access mode) that minimize the end-to-end delay in a multihop linear network, and provide closed-form expressions for the optimal parameter values.

Modeling and Analysis of Abnormality Detection in Biomolecular Nano-Networks

Ghavami, Siavash; Lahouti, Farshad; Masoudi-Nejad, Ali
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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45.68%
A scheme for detection of abnormality in molecular nano-networks is proposed. This is motivated by the fact that early diagnosis, classification and detection of diseases such as cancer play a crucial role in their successful treatment. The proposed nano-abnormality detection scheme (NADS) comprises of a two-tier network of sensor nano-machines (SNMs) in the first tier and a data gathering node (DGN) at the sink. The SNMs detect the presence of competitor cells as abnormality that is captured by variations in parameters of a nano-communications channel. In the second step, the SNMs transmit micro-scale messages over a noisy micro communications channel (MCC) to the DGN, where a decision is made upon fusing the received signals. The detection performance of each SNM is analyzed by setting up a Neyman-Pearson test. Next, taking into account the effect of the MCC, the overall performance of the proposed NADS is quantified in terms of probabilities of misdetection and false alarm. A design problem is formulated, when the optimized concentration of SNMs in a sample is obtained for a high probability of detection and a limited probability of false alarm.; Comment: 31 pages, 13 figures, Invited from IEEE MoNaCom 2012 to Journal of Nano Communication Networks

Directedness of information flow in mobile phone communication networks

Peruani, Fernando; Tabourier, Lionel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/02/2013 Português
Relevância na Pesquisa
45.68%
Without having direct access to the information that is being exchanged, traces of information flow can be obtained by looking at temporal sequences of user interactions. These sequences can be represented as causality trees whose statistics result from a complex interplay between the topology of the underlying (social) network and the time correlations among the communications. Here, we study causality trees in mobile-phone data, which can be represented as a dynamical directed network. This representation of the data reveals the existence of super-spreaders and super-receivers. We show that the tree statistics, respectively the information spreading process, are extremely sensitive to the in-out degree correlation exhibited by the users. We also learn that a given information, e.g., a rumor, would require users to retransmit it for more than 30 hours in order to cover a macroscopic fraction of the system. Our analysis indicates that topological node-node correlations of the underlying social network, while allowing the existence of information loops, they also promote information spreading. Temporal correlations, and therefore causality effects, are only visible as local phenomena and during short time scales. These results are obtained through a combination of theory and data analysis techniques.

Analysis and Modeling of Traffic in Modern Data Communication Networks

Babic, G.; Vandalore, B.; Jain, R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/09/1998 Português
Relevância na Pesquisa
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In performance analysis and design of communication netword modeling data traffic is important. With introduction of new applications, the characteristics of the data traffic changes. We present a brief review the different models of data traffic and how they have evolved. We present results of data traffic analysis and simulated traffic, which demonstrates that the packet train model fits the traffic at source destination level and long-memory (self-similar) model fits the traffic at the aggregate level.; Comment: Ohio State University Technical Report, Feburary 1998

Heterogeneous Recovery Rates against SIS Epidemics in Directed Networks

Qu, Bo; Hanjalic, Alan; Wang, Huijuan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/08/2014 Português
Relevância na Pesquisa
45.68%
The nodes in communication networks are possibly and most likely equipped with different recovery resources, which allow them to recover from a virus with different rates. In this paper, we aim to understand know how to allocate the limited recovery resources to efficiently prevent the spreading of epidemics. We study the susceptible-infected-susceptible (SIS) epidemic model on directed scale-free networks. In the classic SIS model, a susceptible node can be infected by an infected neighbor with the infection rate $\beta$ and an infected node can be recovered to be susceptible again with the recovery rate $\delta$. In the steady state a fraction $y_\infty$ of nodes are infected, which shows how severely the network is infected. We propose to allocate the recovery rate $\delta_i$ for node $i$ according to its indegree and outdegree-$\delta_i\scriptsize{\sim}k_{i,in}^{\alpha_{in}}k_{i,out}^{\alpha_{out}}$, given the finite average recovery rate $\langle\delta\rangle$ representing the limited recovery resources over the whole network. We find that, by tuning the two scaling exponents $\alpha_{in}$ and $\alpha_{out}$, we can always reduce the infection fraction $y_\infty$ thus reducing the extent of infections, comparing to the homogeneous recovery rates allocation. Moreover...

Novel Modulation Techniques using Isomers as Messenger Molecules for Nano Communication Networks via Diffusion

Kim, Na-Rae; Chae, Chan-Byoung
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/07/2012 Português
Relevância na Pesquisa
45.69%
In this paper, we propose three novel modulation techniques, i.e., concentration-based, molecular-type-based, and molecular-ratio-based, using isomers as messenger molecules for nano communication networks via diffusion. To evaluate achievable rate performance, we compare the proposed tech- niques with conventional insulin based concepts under practical scenarios. Analytical and numerical results confirm that the proposed modulation techniques using isomers achieve higher data transmission rate performance (max 7.5 dB signal-to-noise ratio gain) than the insulin based concepts. We also investigate the tradeoff between messenger sizes and modulation orders and provide guidelines for selecting from among several possible candidates.; Comment: 10 pages and 15 figures. arXiv admin note: substantial text overlap with arXiv:1201.0913

Efficient Computation of Distance Sketches in Distributed Networks

Sarma, Atish Das; Dinitz, Michael; Pandurangan, Gopal
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/12/2011 Português
Relevância na Pesquisa
45.7%
Distance computation is one of the most fundamental primitives used in communication networks. The cost of effectively and accurately computing pairwise network distances can become prohibitive in large-scale networks such as the Internet and Peer-to-Peer (P2P) networks. To negotiate the rising need for very efficient distance computation, approximation techniques for numerous variants of this question have recently received significant attention in the literature. The goal is to preprocess the graph and store a small amount of information such that whenever a query for any pairwise distance is issued, the distance can be well approximated (i.e., with small stretch) very quickly in an online fashion. Specifically, the pre-processing (usually) involves storing a small sketch with each node, such that at query time only the sketches of the concerned nodes need to be looked up to compute the approximate distance. In this paper, we present the first theoretical study of distance sketches derived from distance oracles in a distributed network. We first present a fast distributed algorithm for computing approximate distance sketches, based on a distributed implementation of the distance oracle scheme of [Thorup-Zwick, JACM 2005]. We also show how to modify this basic construction to achieve different tradeoffs between the number of pairs for which the distance estimate is accurate and other parameters. These tradeoffs can then be combined to give an efficient construction of small sketches with provable average-case as well as worst-case performance. Our algorithms use only small-sized messages and hence are suitable for bandwidth-constrained networks...

Optimization Problems in Correlated Networks

Yang, Song; Trajanovski, Stojan; Kuipers, Fernando A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/02/2015 Português
Relevância na Pesquisa
45.71%
Solving the shortest path and the min-cut problems are key in achieving high performance and robust communication networks. Those problems have often beeny studied in deterministic and independent networks both in their original formulations as well as in several constrained variants. However, in real-world networks, link weights (e.g., delay, bandwidth, failure probability) are often correlated due to spatial or temporal reasons, and these correlated link weights together behave in a different manner and are not always additive. In this paper, we first propose two correlated link-weight models, namely (i) the deterministic correlated model and (ii) the (log-concave) stochastic correlated model. Subsequently, we study the shortest path problem and the min-cut problem under these two correlated models. We prove that these two problems are NP-hard under the deterministic correlated model, and even cannot be approximated to arbitrary degree in polynomial time. However, these two problems are polynomial-time solvable under the (constrained) nodal deterministic correlated model, and can be solved by convex optimization under the (log-concave) stochastic correlated model.; Comment: 10 pages, 10 figures, Technical Report for the paper: S. Yang...

On the Minimum Number of Wavelengths in Multicast Trees in WDM Networks

Wan, Yingyu; Liang, Weifa
Fonte: Wiley-VCH Verlag GMBH Publicador: Wiley-VCH Verlag GMBH
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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We consider the problem of minimizing the number of wavelengths needed to connect a given multicast set in a multihop WDM optical network. This problem was introduced and studied by Li et al. (Networks, 35(4), 260-265, 2000) who showed that it is NP-complete. They also presented an approximation algorithm for which they claimed an approximation ratio of c(1 +2 log Δ), where c is the maximum number of connected components in the subgraph induced by any wavelength and A is the maximum number of nodes in any connected component induced by any wavelength. In this article we present an example demonstrating that their claim cannot be correct-the approximation ratio is Ω(n), even though the subgraph induced by every wavelength is connected, where n is the number of nodes in the network. In fact, we show that the problem cannot be approximated within O(2log1/2-ε) unless NP ⊆ DTIME(n poly log n) for any constant E > 0, where m is the number of edges in the network. We complement this hardness result by presenting a polynomial-time algorithm with an approximation ratio of (1 + In 3 + 2 log Δ) when the subgraph induced by every wavelength is connected, and an approximation ratio of O(√(n log Δ)/opt) in the general case, where opt is the number of wavelengths used in an optimal solution and 1 ≤ opt ≤ n - 1.