Traditional content-based image retrieval (CBIR) systems use low-level features such as colors, shapes, and textures of images. Although, users make queries based on semantics, which are not easily related to such low-level characteristics. Recent works on CBIR confirm that researchers have been trying to map visual low-level characteristics and high-level semantics. The relation between low-level characteristics and image textual information has motivated this article which proposes a model for automatic classification and categorization of words associated to images. This proposal considers a self-organizing neural network architecture, which classifies textual information without previous learning. Experimental results compare the performance results of the text-based approach to an image retrieval system based on low-level features. (c) 2008 Wiley Periodicals, Inc.
A tecnologia de chaveamento de pacotes ópticos comumente utiliza componentes muito complexos, relegando sua viabilidade para o futuro. A utilização de pacotes ópticos, entretanto, é uma boa opção para melhorar a granularidade dos enlaces ópticos, bem como para tornar os processos de distribuição de banda muito mais eficientes e flexíveis. Esta tese propõe simplificações nas chaves ópticas que além de tornarem o pacote óptico viável para um futuro mais próximo, permitem montar redes ópticas complexas, com muitos nós, que operam de maneira auto-organizada. A rede proposta nesta tese não possui sinalização para reserva ou estabelecimento de caminho. As rotas são definidas pacote a pacote, em tempo real, durante o seu percurso, utilizando roteamento por deflexão. Com funções muito simples realizadas localmente, a rede ganha características desejáveis como: alta escalabilidade e eficiente sistema de proteção de enlace. Estas características desejáveis são tratadas como funções da rede que emergem de funções realizadas em cada um dos nós de rede individualmente. A tese apresenta um modelo analítico estatístico, validado por simulação, para caracterização da rede. No sistema de proteção contra falhas...
Os avanços nas áreas de comunicação sem fio e microeletrônica têm motivado o desenvolvimento de aplicações utilizando equipamentos sem fio, especialmente dispositivos sensores e atuadores, permitindo assim, a criação de uma ponte tecnológica para conectar o mundo físico com o mundo digital. Com essa interação surge uma demanda crescente por sistemas de monitoramento e controle em ambientes industriais, residenciais e também municipais. Algumas tecnologias já se encontram no mercado, destinadas a este tipo de aplicação e dentre elas destaca-se a especificação ZigBee. Entretanto, aplicações em cenários metropolitanos exigem um paradigma de comunicação com alta capacidade e de larga escala. Este trabalho apresenta uma arquitetura híbrida e hierárquica de rede de sensores/atuadores para aplicação em cenários metropolitanos. A arquitetura proposta faz uso do potencial da especificação ZigBee e da capacidade das Redes Metropolitanas de Acesso Aberto. Baseado em tal arquitetura, um estudo de caso foi desenvolvido na cidade de Pedreira, interior do estado de São Paulo, onde foi implementado um sistema para supervisão do fluxo de pessoas, monitoramento do ambiente e controle de dispositivos em um prédio do setor público.; The advances in wireless communication technology and microelectronics have enable interesting new application for wireless devices...
Considerando-se que para controlar e possibilitar a entrega de diversos conteúdos e serviços a qualquer tipo de acesso fazia-se necessário um núcleo bem definido e estruturado, surgiu o IMS (IP Multimedia Subsystem) com o propósito de prover a integração completa das redes e serviços. O IMS define uma arquitetura completa e framework que habilita a convergência de voz, vídeo, dados e tecnologia de rede móvel através de uma infraestrutura baseada em IP, preenchendo a distância entre os dois paradigmas de comunicação mais bem sucedidos, celular e tecnologia IP. Este trabalho apresenta a arquitetura IMS como controle central de todas as redes, e uma arquitetura para o desenvolvimento de aplicações móveis que incorporem voz, vídeo e dados. A arquitetura IMS apesar de promissora apresenta inúmeras oportunidades de melhoria no seu mecanismo de segurança, muitas dessas oportunidades de melhoria estão relacionadas a falhas e até mesmo a falta de especificações de segurança quando a arquitetura foi originalmente implementada. Assim o maior desafio na implantação e globalização da arquitetura IMS são as falhas de segurança e a vulnerabilidade que a arquitetura possui a diversos tipos de ataques que podem atingir e prejudicar...
Atualmente provedores de infraestrutura (Infrastructure Providers - InPs) alocam recursos virtualizados, computacionais e de rede, de seus data centers para provedores de serviços na forma de data centers virtuais (Virtual Data Centers - VDCs). Almejando maximizar seus lucros e usar de forma eficiente os recursos de seus data centers, InPs lidam com o problema de otimizar a alocação de múltiplos VDCs. Mesmo que a alocação de máquinas virtuais em servidores seja feita de maneira otimizada por diversas técnicas e algoritmos já existentes, aplicações de computação em nuvem ainda tem o desempenho prejudicado pelo gargalo do subaproveitamento de recursos de rede, explicitamente definidos por limitações de largura de banda e latência. Baseado no paradigma de Redes Definidas por Software, nós aplicamos o modelo de rede como serviço (Network-as-a-Service - NaaS) para construir uma arquitetura de data center bem definida para dar suporte ao problema de aprovisionamento de redes virtuais em data centers. Construímos serviços sobre o plano de controle da plataforma RouteFlow os quais tratam a alocação de redes virtuais de data center otimizando a utilização de recursos da infraestrutura de rede. O algoritmo proposto neste trabalho realiza a tarefa de alocação de redes virtuais...
In the absence of sensory stimulation, neocortical circuits display complex patterns of neural activity. These patterns are thought to reflect relevant properties of the network, including anatomical features like its modularity. It is also assumed that the synaptic connections of the network constrain the repertoire of emergent, spontaneous patterns. Although the link between network architecture and network activity has been extensively investigated in the last few years from different perspectives, our understanding of the relationship between the network connectivity and the structure of its spontaneous activity is still incomplete. Using a general mathematical model of neural dynamics we have studied the link between spontaneous activity and the underlying network architecture. In particular, here we show mathematically how the synaptic connections between neurons determine the repertoire of spatial patterns displayed in the spontaneous activity. To test our theoretical result, we have also used the model to simulate spontaneous activity of a neural network, whose architecture is inspired by the patchy organization of horizontal connections between cortical columns in the neocortex of primates and other mammals. The dominant spatial patterns of the spontaneous activity...
A service-providing system consists of hosts that provide services such as data, content, computational and memory resources and data-based services to other entities in the system. Consumers that wish to use services describe their needs with a set of high-level objectives. In this thesis, we address the problem of locating services in a large-scale distributed system using their descriptions, rather than their addresses. We propose a network architecture that is based on the concept of dividing the service-providing hosts into Regions. A Region is a grouping of elements of the network that share a set of common characteristics and policies. Members of a region manage their interactions with other regions and their elements according to some defined rules and policies. Hosts can be divided into regions based on various properties such as their content, their commercial model or their security characteristics to name a few. The service provided by a region is an ! aggregate of the services provided by all its member hosts. The region-based architecture routes a service request through the network efficiently based on its description and on the advertisements from regions providing services. Division of hosts into a set of independent regions partitions the search space and produces a scalable structure. The architecture also does not impose any rules on the internal organization of regions making the system flexible and dynamic.
This thesis proposes a network architecture, called SMPL, for the design and development of collaboration-oriented, distributed applications over the Internet. The goal of SMPL is to enable the development of applications that easily integrate the capabilities of different types of computing resources, software platforms, and data repositories across the Internet transcending the level of a single device. SMPL proposes a new abstraction of the Internet as a network composed of services, resources, and capabilities instead of just machines. The SMPL architecture distributes resources through a peer-to-peer network of service providers. The design of SMPL encourages developers to add value to the system by facilitating the creation of new functionalities based upon compositions of the existing ones.; Carlos A. Rocha.; Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2005.; Includes bibliographical references (p. 85-89).
To provide end users with economic access to high bandwidth, the architecture of the next generation metropolitan area networks (MANs) needs to be judiciously designed from the cost perspective. In addition to a low initial capital investment, the ultimate goal is to design networks that exhibit excellent scalability - a decreasing cost-per-node-per-unit-traffic as user number and transaction size increase. As an effort to achieve this goal, in this thesis we search for the scalable network architectures over the solution space that embodies the key aspects of optical networks: fiber connection topology, switching architecture selection and resource dimensioning, routing and wavelength assignment (RWA). Due to the inter-related nature of these design elements, we intended to solve the design problem jointly in the optimization process in order to achieve over-all good performance. To evaluate how the cost drives architectural tradeoffs, an analytical approach is taken in most parts of the thesis by first focusing on networks with symmetric and well defined structures (i.e., regular networks) and symmetric traffic patterns (i.e., all-to-all uniform traffic), which are fair representations that give us suggestions of trends, etc.; (cont.) We starts with a examination of various measures of regular topologies. The average minimum hop distance plays a crucial role in evaluating the efficiency of network architecture. From the perspective of designing optical networks...
Infrastructureless wireless networks are an important class of wireless networks that is best suited for scenarios where there is temporary and localized telecommunication demand. Such networks consist of wireless devices that can form a network autonomously without the need for pre-deployed telecommunication infrastructures such as base-stations and access points. Over the past several decades, significant research and development efforts have been devoted to a particular type of infrastructureless wireless networks called mobile ad hoc wireless networks (MANETs). In addition to autonomous network formation, wireless devices in MANETs have routing capabilities and help one another to forward information in a multihop fashion. The applications envisioned for MANETs include communication during disaster relief, search and rescue, and small tactical unit operations where the existing telecommunication infrastructures may be destroyed or are unavailable. While significant strides have been made in all aspects of MANET networking, adoption of such technology has been limited to date despite its potential. We believe that this lack of adoption is due to a fundamental mismatch between application demands and the MANET network architecture. While the flexibility of anytime and anywhere communication offered by MANETs is appealing...
Machine virtualization has become a cornerstone of modern datacenters. It enables server consolidation as a means to reduce costs and increase efficiencies. The communication endpoints within the datacenter are now virtual machines (VMs), not physical servers. Consequently, the datacenter network now extends into the server and last hop switching occurs inside the server. Today, thanks to increasing core counts on processors, server VM densities are on the rise. This trend is placing enormous pressure on the network I/O subsystem and the last hop virtual switch to support efficient communication, both internal and external to the server. But the current state-of-the-art solutions fall short of these requirements. This thesis presents new architectures and mechanisms for the network subsystem in virtualized servers to build efficient virtualization platforms.
Specifically, there are three primary contributions in this thesis. First, it presents a new mechanism to reduce memory sharing overheads in driver domain-based I/O architectures. The key idea is to enable a guest operating system to reuse its I/O buffers that are shared with a driver domain. Second, it describes Hyper-Switch, a highly streamlined, efficient, and scalable software-based virtual switching architecture...
Air surveillance radar tracking systems present a variety of known problems related to uncertainty and lack of accurately in radar measurements used as source in these systems. In this work, we feature the theoretical aspects of a tracking algorithm based on neural network paradigm where, from discrete measurements provided by surveillance radar, the objective will be to estimate the target state for tracking purposes as accuracy as possible. The absence of an optimal statistical solution makes the featured neural network attractive despite the availability of complex and well-known filtering algorithms.Neural networks exhibit universal mapping capabilities that allow them to be used as a control tool for capturing hidden information about models learned from a dataset. We use these capabilities to let the network learn, not only from the received radar measurement information, but also from the aircraft maneuvering context, contextual information, where tracking application is working, taking into account this new contextual information which could be obtained from predefined, commonly used, and well-known aircraft trajectories. In this case study, the proposed solution is applied to a typical air combat maneuvering, a dogfight, a form of aerial combat between fighter aircraft. Advantages of integrating contextual information in a neural network tracking approach are demonstrated.; This work was supported in part by ProjectsMEyC TEC2012-
This thesis presents a mathematical framework for real-time sensor-driven stochastic modeling of story and user-story interaction, which I call sto(ry)chastics. Almost all sensor-driven interactive entertainment, art, and architecture installations today rely on one-to-one mappings between content and participant's actions to tell a story. These mappings chain small subsets of scripted content, and do not attempt to understand the public's intention or desires during interaction, and therefore are rigid, ad hoc, prone to error, and lack depth in communication of meaning and expressive power. Sto(ry)chastics uses graphical probabilistic modeling of story fragments and participant input, gathered from sensors, to tell a story to the user, as a function of people's estimated intentions and desires during interaction. Using a Bayesian network approach for combined modeling of users, sensors, and story, sto(ry)chastics, as opposed to traditional systems based on one- to-one mappings, is flexible, reconfigurable, adaptive, context-sensitive, robust, accessible, and able to explain its choices. To illustrate sto(ry)chastics, this thesis describes the museum wearable, which orchestrates an audiovisual narration as a function of the visitor's interests and physical path in the museum. The museum wearable is a lightweight and small computer that people carry inside a shoulder pack. It offers an audiovisual augmentation of the surrounding environment using a small eye-piece display attached to conventional headphones. The wearable prototype described in this document relies on a custom-designed; (cont.) long-range infrared location-identification sensor to gather information on where and how long the visitor stops in the museum galleries. It uses this information as input to...
We introduce an application of a mobile transient network architecture on top
of the current Internet. This paper is an application extension to a conceptual
mobile network architecture. It attempts to specifically reinforce some of the
powerful notions exposed by the architecture from an application perspective.
Of these notions, we explore the network expansion layer, an overlay of
components and services, that enables a persistent identification network and
other required services. The overlay abstraction introduces several benefits of
which mobility and communication across heterogenous network structures are of
interest to this paper. We present implementations of several components and
protocols including gateways, Agents and the Open Device Access Protocol. Our
present identification network implementation exploits the current
implementation of the Handle System through the use of distributed, global and
persistent identifiers called handles. Handles are used to identify and locate
devices and services abstracting any physical location or network association
from the communicating ends. A communication framework is finally demonstrated
that would allow for mobile devices on the public Internet to have persistent
identifiers and thus be persistently accessible either directly or indirectly.
This application expands IP inter-operability beyond its current boundaries.
We propose a percolation based M2M networking architecture and its data
transmission method. The proposed network architecture can be server-free and
router-free, which allows us to operate routing efficiently with percolations
based on six degrees of separation theory in small world network modeling. The
data transmission can be divided into two phases: routing and data transmission
phases. In the routing phase, probe packets will be transmitted and forwarded
in the network thus multiple paths are selected and performed based on the
constriction of the maximum hop number. In the second phase, the information
will be encoded, say, with the fountain codes, and transmitted using the paths
generated in the first phase. In such a way, an efficient routing and data
transmission mechanism can be built, which allow us to construct a low-cost,
flexible and ubiquitous network. Such a networking architecture and data
transmission can be used in many M2M communications, such as the stub network
of internet of things, and deep space networking, and so on.; Comment: 15 pages, 7 figures. We propose a percolation based routing and data
transmission method for the M2M network, which consists of routing phase and
transmission phases. In the routing phase...
A nationwide interoperable public safety broadband network is being planned
by the United States government. The network will be based on long term
evolution (LTE) standards and use recently designated spectrum in the 700 MHz
band. The public safety network has different objectives and traffic patterns
than commercial wireless networks. In particular, the public safety network
puts more emphasis on coverage, reliability and latency in the worst case
scenario. Moreover, the routine public safety traffic is relatively light,
whereas when a major incident occurs, the traffic demand at the incident scene
can be significantly heavier than that in a commercial network. Hence it is
prohibitively costly to build the public safety network using conventional
cellular network architecture consisting of an infrastructure of stationary
base transceiver stations. A novel architecture is proposed in this paper for
the public safety broadband network. The architecture deploys stationary base
stations sparsely to serve light routine traffic and dispatches mobile base
stations to incident scenes along with public safety personnel to support heavy
traffic. The analysis shows that the proposed architecture can potentially
offer more than 75% reduction in terms of the total number of base stations
needed.; Comment: ICC 2013
Heterogeneous Vehicular NETworks (HetVNETs) can meet various
quality-of-service (QoS) requirements for intelligent transport system (ITS)
services by integrating different access networks coherently. However, the
current network architecture for HetVNET cannot efficiently deal with the
increasing demands of rapidly changing network landscape. Thanks to the
centralization and flexibility of the cloud radio access network (Cloud-RAN),
soft-defined networking (SDN) can conveniently be applied to support the
dynamic nature of future HetVNET functions and various applications while
reducing the operating costs. In this paper, we first propose the multi-layer
Cloud RAN architecture for implementing the new network, where the multi-domain
resources can be exploited as needed for vehicle users. Then, the high-level
design of soft-defined HetVNET is presented in detail. Finally, we briefly
discuss key challenges and solutions for this new network, corroborating its
feasibility in the emerging fifth-generation (5G) era.
Ubiquitous sensing devices frequently disseminate data among them. The use of
a distributed event-based system that decouples publishers from subscribers
arises as an ideal candidate to implement the dissemination process. In this
paper, we present a network architecture that merges the network and overlay
layers of typical structured event-based systems. Directional random walks are
used for the construction of this merged layer. Our strategy avoids using a
specific network protocol that provides point-to-point communication. This
implies that the topology of the network is not maintained, so that nodes not
involved in the system are able to save energy and computing resources. We
evaluate the performance of the overlay layer using directional random walks
and pure random walks for its construction. Our results show that directional
random walks are more efficient because: (1) they use less nodes of the network
for the establishment of the active path of the overlay layer and (2) they have
a more reliable performance. Furthermore, as the number of nodes in the network
increases, so do the number of nodes in the active path of the overlay layer
for the same number of publishers and subscribers. Finally, we discard any
correlation between the number of nodes that form the overlay layer and the
maximum Euclidean distance traversed by the walkers.; Comment: 10 pages. arXiv admin note: text overlap with arXiv:1408.3033
Ubiquitous sensing devices frequently disseminate their data between them.
The use of a distributed event-based system that decouples publishers of
subscribers arises as an ideal candidate to implement the dissemination
process. In this paper, we present a network architecture which merges the
network and overlay layers of typical structured event-based systems.
Directional Random Walks (DRWs) are used for the construction of this merged
layer. Our first results show that DRWs are suitable to balance the load using
a few nodes in the network to construct the dissemination path. As future work,
we propose to study the properties of this new layer and to work on the design
of Bloom filters to manage broker nodes.; Comment: 5 pages, 6 figures
In this research paper, the problems dealing with sensor network
architecture, sensor fusion are addressed. Time/Computationally optimal network
architectures are investigated. Some novel ideas on sensor fusion are proposed.