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Comportamento estrutural de pontes estaiadas: comparação de alternativas. ; Structural behavior of cable-stayed bridges: comparison of alternatives.

Torneri, Paola
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/09/2002 PT
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Nos últimos anos, a utilização de pontes estaiadas tem evoluído rapidamente e novos conceitos estruturais têm surgido, como por exemplo: o desenvolvimento de seções flexíveis e esbeltas, o aumento do comprimento dos vãos e a aplicação de pontes estaiadas em múltiplos vãos. Torna-se necessário portanto uma compreensão profunda do comportamento estrutural desse sistema. No processo de projeto as decisões mais importantes são geralmente feitas nas fases iniciais quando a síntese predomina sobre a análise numérica, tornando fundamental o entendimento do comportamento físico da estrutura na fase de pré-dimensionamento. Na concepção de uma ponte estaiada inúmeras alternativas estruturais são possíveis, por exemplo: pode-se utilizar um ou dois planos de cabos em diferentes arranjos, mastros e tabuleiros com seções transversais diversas e diferentes tipos de vinculação externa. Para um dado problema, mais de uma solução pode ser viável, no entanto algumas delas propiciarão a maior eficiência, sob o ponto de vista de consumo de materiais, facilidades construtivas, prazo de execução e comportamento físico da estrutura. Neste trabalho foram analisadas diferentes concepções estruturais com o objetivo de fornecer subsídios para as decisões tomadas no início do projeto estrutural de uma ponte estaiada. Para tanto...

Estudo de pontes de madeira com tabuleiro multicelular protendido ; Study of timber bridges with multicellular prestressed decks

Góes, Jorge Luís Nunes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 30/05/2005 PT
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As pontes de madeira com tabuleiro multicelular protendido são uma das mais recentes tecnologias usadas na construção das modernas pontes de madeira. Nesta tese é realizado o estudo teórico e experimental do comportamento estrutural destas pontes. Os principais métodos de cálculo são apresentados e discutidos. A investigação experimental foi realizada em dois modelos reduzidos em escala 1:3 com as mesmas dimensões externas mas diferente quantidade de nervuras. Os modelos foram ensaiados com diferentes posições de carregamento enquanto os deslocamentos, deformações e forças nas barras, eram monitorados. Os resultados obtidos demonstraram que os modelos de Placa Ortotrópica Equivalente e Elementos Finitos podem ser empregados para o dimensionamento das pontes de madeira com tabuleiro multicelular protendido. O método de Viga Equivalente pode ser empregado desde que utilizado o correto Fator de Distribuição de Carga. Os estudos realizados neste trabalho, indicam a viabilidade da utilização deste sistema estrutural para pontes com vãos de 12 a 25 m; Timber bridges with multicellular prestressed decks is one of the most recent technology for modern timber bridges construction. In this thesis the theoretical and experimental study of the structural behavior of these bridges is accomplished. The main calculation methods are introduced and discussed. Two reduced models on scale 1:3...

Comportamento estrutural de pontes com protensão no extradorso. ; Structural behavior of extradosed bridges.

Santos, Daniel Miranda dos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/07/2006 PT
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Nos últimos anos, a protensão externa aplicada a estruturas de pontes tem evoluído de forma excepcional, o que permite maior liberdade de projeto e, consequentemente, possibilita o surgimento de novas tipologias estruturais. Um exemplo desse desenvolvimento é a ponte com protensão no extradorso, que começa a se difundir no meio técnico como uma transição econômica entre as pontes de concreto protendido e as estaiadas. A idéia, atribuída ao engenheiro francês Jacques Mathivat, consiste em utilizar protensão externa sobre os apoios intermediários, com o auxílio de pequenas torres. Neste trabalho é apresentada uma revisão bibliográfica ampla sobre os diversos tipos de pontes com emprego de protensão, visando focar nos aspectos importantes e que auxiliam no entendimento do comportamento estrutural das pontes com protensão no extradorso. É realizado, também, um estudo da flutuação de tensão nos cabos de protensão, com vistas à fadiga dos mesmos, que é um fator de extrema importância. Além disso, é realizado um vasto estudo paramétrico de diversos tipos de modelos estruturais, que têm por objetivo um aprofundamento da compreensão do comportamento estrutural das pontes com protensão no extradorso, sendo que...

Sistemas estruturais de pontes extradorso.; Structural configuration of extradosed bridges.

Ishii, Marcio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/11/2006 PT
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37.01%
As pontes extradorso surgiram na última década do Século XX, principalmente pelo extraordinário desenvolvimento tecnológico do concreto protendido, que possibilitou uma solução simples e econômica para a construção de pontes. A Odawara Blueway Bridge, construída em 1995 no Japão, foi a primeira ponte extradorso do mundo. Depois dessa obra, dezenas de outras pontes foram construídas com esse sistema estrutural, principalmente na Ásia, comprovando sua viabilidade técnica e econômica. Todavia, não se tem conhecimento de algum estudo que mostre em que faixa de extensão de vãos as superestruturas de pontes extradorso são economicamente vantajosas em relação a outros sistemas estruturais. Neste trabalho foi realizada uma investigação visando um estudo comparativo entre as superestruturas de pontes em viga reta de concreto protendido e as pontes extradorso, ambas construídas pelo método dos balanços progressivos. Na investigação realizada verificou-se que as pontes extradorso são economicamente competitivas com a ponte em viga reta de concreto protendido, principalmente na faixa de vãos entre 100 e 200 metros.; The extradosed bridges had appeared in the last decade of XX Century, mainly because the extraordinary technological development of the prestressed concrete made possible a simple and economic solution for the construction of bridges. The Odawara Blueway Bridge...

Histórico das pontes estaiadas e sua aplicação no Brasil.; History of cable stayed bridges and its application in Brazil.

Mazarim, Diego Montagnini
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/06/2011 PT
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O princípio estrutural das pontes estaiadas não é tão recente quanto as pontes propriamente ditas. Em algumas estruturas, tais como passarelas, embarcações e tendas, já se usavam cabos como sustentação. Com a evolução da tecnologia e dos materiais, houve a possibilidade de um aperfeiçoamento dessas técnicas e sua utilização nas mais diversas áreas. As pontes estaiadas surgiram como uma alternativa eficaz para transpor grandes vãos, possibilitando a utilização de estruturas mais leves, esbeltas e econômicas. Este trabalho apresenta a evolução das pontes estaiadas no mundo e no Brasil, enfatizando os seus aspectos históricos, as novas tecnologias empregadas nestes projetos, as diversas possibilidades de geometria da estrutura e os métodos construtivos empregados nestas pontes. Para as pontes estaiadas ao redor do mundo, é elaborada uma análise geral, demonstrando sua importância ao longo da história e as vantagens que as mesmas propiciaram para o suprimento das necessidades da humanidade. Fazendo uma análise especial das pontes estaiadas brasileiras, é elaborada uma listagem das mesmas por ordem cronológica, indicando suas principais características. Finalmente, para as pontes estaiadas nacionais de maior destaque...

Assignment of the disulfide bridges in bothropstoxin-I, a myonecrotic Lys49 PLA(2) homolog from Bothrops jararacussu snake venom

Cintra, ACO; Sampaio, S. V.; Raghuvir, A. K.; Giglio, JR
Fonte: Kluwer Academic/plenum Publ Publicador: Kluwer Academic/plenum Publ
Tipo: Artigo de Revista Científica Formato: 377-382
ENG
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Bothropstoxin-I (BthTX-1), a Lys49 phospholipase A(2) homolog with no apparent catalytic activity, was first isolated from Bothrops jararacussu snake venom and completely sequenced in this laboratory. It is a 121-amino-acid single polypeptide chain, highly myonecrotic, despite its inability to catalyze hydrolysis of egg yolk phospholipids, and has 14 half-cystine residues identified at positions 27, 29, 44, 45, 50, 51, 61, 84, 91, 96, 98, 105, 123, and 131 (numbering according to the conventional alignment including gaps, so that the last residue is Cys 131). In order to access its seven disulfide bridges, two strategies were followed: (1) Sequencing of isolated peptides from (tryptic + SV8) and chymotryptic digests by Edman-dansyl degradation; (2) crystallization of the protein and determination of the crystal structure so that at least two additional disulfide bridges could be identified in the final electron density map. Identification of the disulfide-containing peptides from the enzymatic digests was achieved following the disappearance of the original peptides from the HPLC profile after reduction and carboxymethylation of the digest. Following this procedure, four bridges were initially identified from the tryptic and SV8 digests: Cys50-Cys131...

Assignment of the bisulfide bridges in bothropstoxin-I, a Myonecrotic Lys49 PLA2 homolog from bothrops jararacussu snake venom

Cintra, Adélia C.O.; Sampaio, Suely V.; Raghuvir, Ami K.; Giglio, José R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 377-382
ENG
Relevância na Pesquisa
36.86%
Bothropstoxin-I (BthTX-I), a Lys49 phospholipase A2 homolog with no apparent catalytic activity, was first isolated from Bothrops jararacussu snake venom and completely sequenced in this laboratory. It is a 121-amino-acid single polypeptide chain, highly myonecrotic, despite its inability to catalyze hydrolysis of egg yolk phospholipids, and has 14 half-cystine residues identified at positions 27, 29, 44, 45, 50, 51, 61, 84, 91, 96, 98, 105, 123, and 131 (numbering according to the conventional alignment including gaps, so that the last residue is Cys 131). In order to access its seven disulfide bridges, two strategies were followed: (1) Sequencing of isolated peptides from (tryptic + SV8) and chymotryptic digests by Edman-dansyl degradation; (2) crystallization of the protein and determination of the crystal structure so that at least two additional disulfide bridges could be identified in the final electron density map. Identification of the disulfide-containing peptides from the enzymatic digests was achieved following the disappearance of the original peptides from the HPLC profile after reduction and carboxymethylation of the digest. Following this procedure, four bridges were initially identified from the tryptic and SV8 digests: Cys50-Cysl31...

Comparative structural response of two steel bridges constructed 100 years apart

Varum, Humberto; Sousa, Romain; Delgado, Walter; Fernandes, Catarina; Costa, Anibal; Jara, Jose M.; Jara, Manuel; Álvarez, Jose J.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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This paper presents a comparative numerical analysis of the structural behaviour and seismic performance of two existing steel bridges, the Infiernillo II Bridge and the Pinhao Bridge, one located in Mexico and the other in Portugal. The two bridges have similar general geometrical characteristics, but were constructed 100 years apart. Three-dimensional structural models of both bridges are developed and analysed for various load cases and several seismic conditions. The results of the comparative analysis between the two bridges are presented in terms of natural frequencies and corresponding vibration modes, maximum stresses in the structural elements and maximum displacements. The study is aimed at determining the influence of a 1 century period in material properties, transverse sections and expected behaviour of two quite similar bridges. In addition, the influence of the bearing conditions in the global response of the Pinhao Bridge was evaluated.

Transverse load distribution of skew cast-in-place concrete multicell box - girder bridges subjected to traffic condition

Mohseni,Iman; Khalim Rashid,A.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
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Concrete multicell box-girder bridges are a common choice among the designers for various ranges of bridges. In order to provide safer and greater speed of traffic, the roadway is built as straight as possible. The use of skewed bridges has increased considerably in the recent years for roadway. The skewed bridges have quite different mechanical behavior from the straight bridges, although for skew angles less than 20 degrees, it is reasonably safe to ignore the effect of skew angles and analyze that at the straight bridge. In this study, in developing an analytical solution, an extensive parametric study was carried out to determine the maximum positive and negative stress distribution factors and to calculate the maximum distribution factor of deflection along the mid-span of skewed multicell box-girder bridges. A total of 240 representative bridges numerical models were selected and analyzed using SAP2000 finite element software. It was found that the span length, number of boxes, number of lanes and skew angles significantly affected the distribution factors of stress and deflection. Finally, several equations were proposed for stress and deflection distribution factors of multicell box-girder bridges for the application of American Association of State Highway and Transportation officials load and resistance factor design live loads.

Metodologia de Inspeção em Estruturas de Pontes de Concreto Armado; Methodology for inspection of concret bridges

EUQUERES, Priscilla
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias
Tipo: Dissertação Formato: application/pdf
POR
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The objective this work is to develop and implement a methodology for special inspection on Concrete Bridges trough the quantitative analysis of the degree of deterioration of the structures so that it can serve as a basis for making decisions related to the rehabilitation of these structures. In order to develop and apply the methodology on concrete bridges, the existing methods of inspection of concrete structures were studied and adapted to the adapting to the concrete bridges. The methodology was based on GDE/UnB model in their latest formulation (Fonseca,2007) and adapted to the tables with the elements to be analyzed, together with the pathological manifestations that can occur in each element, timing and interventions classification of the level of deterioration and the relevant factors to each family of concrete bridges. A pilot study was proposed to validate the methodology. Results showed that there was a need for further adaptation, to consider the caculations of the degree of deterioration of both the family or the. With the changes proposed in the pilot study were made over 11 (eleven) inspections in order to validate the proposed methodology. With the results obtained it was concluded that the methodology for inspection of bridges is valid and of great importance to public organisms and surveyors to make decisions about the best time and the best item to be rehabilitated...

AEROELASTICITY OF SUSPENSION BRIDGES USING NONLINEAR AERODYNAMICS AND GEOMETRICALLY EXACT STRUCTURAL MODELS

ARENA, ANDREA
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
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Wind-induced vibration in super-long-span bridges is a major concern for the designers. There is a need to enhance the structural design technology, through improved computational capabilities, a critical step for a better understanding of fluid-flow physics that induce vibration and fluid- structure dynamics of flexible bridges. The design of bridges with spans significantly longer than those existing today is quite challenging. To refine the computational tools required for such bridges, a multi- disciplinary research effort devoted to the advanced modeling of flexible long-span suspension bridges is proposed. These structures exhibit an aeroelastic behavior quite different from conventional bridges. In the present work, a fully nonlinear model of suspension bridges parameterized by one single space coordinate is proposed to describe the overall three-dimensional motion. The nonlinear equations of motion are obtained via a direct Lagrangian formulation and the kinematics, for the deck-girder and the suspension cables, feature the finite displacements of the associated base lines and the flexural and torsional finite rotations of the deck cross sections. The strain-displacement relationships for the generalized strain parameters - the cable elongations...

Comprehending Performance of Cross-Frames in Skewed Straight Steel I-Girder Bridges

Gull, Jawad H
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
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The effects of support in steel bridges can present significant challenges during the construction. The tendency of girders to twist or layovers during the construction can present a particularly challenging problem regarding detailing cross-frames that provide bracing to steel girders. Methods of detailing cross-frames have been investigated in the past to identify some of the issues related to the behavior of straight and skewed steel bridges. However, the absence of a complete and simplified design approach has led to disputes between stakeholders, costly repairs and delays in the construction. The main objective of this research is to develop a complete and simplified design approach considering construction, fabrication and detailing of skewed bridges. This objective is achieved by comparing different detailing methods, understanding the mechanism by which skew effects develop in steel bridges, recommending simplified methods of analysis to evaluate them, and developing a complete and simplified design procedure for skew bridges. Girder layovers, flange lateral bending stress, cross-frame forces, component of vertical deflections, component of vertical reactions and lateral reactions or lateral displacements are affected by detailing methods and are referred as lack-of-fit effects. The main conclusion of this research is that lack-of-fit effects for the Final Fit detailing method at the steel dead load stage are equal and opposite to the lack-of-fit effects for the Erected Fit detailing method at the total dead load stage. This conclusion has helped using 2D grid analyses for estimating these lack-of-fit effects for different detailing methods. 3D erection simulations are developed for estimating fit-up forces required to attach the cross-frames to girders. The maximum fit-up force estimated from the 2D grid analysis shows a reasonable agreement with the one obtained from the erection simulations. The erection sequence that reduces the maximum fit-up force is also found by erection simulations. The line girder analysis is recommended for calculating cambers for the Final Fit detailing method. A combination of line girder analysis and 2D grid analysis is recommended for calculating cambers for the Erected Fit detailing method. Finally...

Dynamic Behavior and Fatigue Life of Highway Bridges Due to Doubling Heavy Vehicles

Tarighi, Arash
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
36.96%
An increase in the demand for the freight shipping in the United States has been predicted for the near future and Longer Combination Vehicles (LCVs), which can carry more loads in each trip, seem like a good solution for the problem. Currently, utilizing LCVs is not permitted in most states of the US and little research has been conducted on the effects of these heavy vehicles on the roads and bridges. In this research, efforts are made to study these effects by comparing the dynamic and fatigue effects of LCVs with more common trucks. Ten Steel and prestressed concrete bridges with span lengths ranging from 30’ to 140’ are designed and modeled using the grid system in MATLAB. Additionally, three more real bridges including two single span simply supported steel bridges and a three span continuous steel bridge are modeled using the same MATLAB code. The equations of motion of three LCVs as well as eight other trucks are derived and these vehicles are subjected to different road surface conditions and bumps on the roads and the designed and real bridges. By forming the bridge equations of motion using the mass, stiffness and damping matrices and considering the interaction between the truck and the bridge, the differential equations are solved using the ODE solver in MATLAB and the results of the forces in tires as well as the deflections and moments in the bridge members are obtained. The results of this study show that for most of the bridges...

Vulnerability Assessment of Coastal Bridges Subjected to Hurricane Events

Ataei, Navid
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
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Bridges are the most critical components of the transportation network. The functionality of bridges is important for hurricane aftermath recovery and emergency activities. However, past hurricane events revealed the potential susceptibility of these bridges under storm induced wave and surge loads. Coastal bridges traditionally were not designed to sustain hurricane induced wave and surge loads; and furthermore, no reliability assessment tool exists for bridges exposed to this hazard. However, such a tool is imperative for decision makers to evaluate the risk posed to the existing bridge inventory, and to decide on the retrofit measures and mitigation strategies. This dissertation offers a first attempt to quantify the structural vulnerability of bridges under coastal storms, offering a probabilistic framework, input tools, and application illustrations. To accomplish this goal, first an unbiased wave load model is developed based on the existing wave load models in the literature. The biased is removed from the load models through statistical analysis of the experimental test data. The developed wave load model is used to evaluate the response of coastal bridges employing single-physics domain Dynamic numerical models. Additionally...

RISK-BASED DESIGN OF BRIDGES AND ASSOCIATED TRANSPORTATION NETWORKS UNDER NATURAL HAZARDS

Wang, Zhenghua
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
37.04%
The highway infrastructure system in the United States is deteriorating and facing an increased number of threats from natural and man-made hazards, including earthquakes, scour, hurricanes, and vehicle collisions. At the same time, the reliable functioning of the highway system plays an important role in emergency response and recovery processes after disaster strikes. However, there are several inadequacies in current codes and associated practice for the design of bridges, as well as funding restrictions for their upkeep. Although recent changes in the seismic design of bridges have adopted displacement-based design approaches to promote adequate performance under seismic loads, the current design philosophy hinges upon a uniform hazard perspective without explicit consideration of a homogeneous risk of damage or collapse. In addition, this approach does not reflect the influence of individual bridges on the transportation network behaviour, which is desirable to estimate the performance of a transportation infrastructure system and enhance its overall post-event operation. Moreover, current bridge design specifications deal with various extreme hazards independent of one another. The reliable performance of transportation infrastructure systems under natural hazards requires a new life-cycle risk-based design method...

Implementing ARP-Path Low Latency Bridges in NetFPGA

Rojas, Elisa; Naous, Jad; Ibañez, Guillermo; Rivera, Diego; Carral, Juan A.; Arco, José M.
Fonte: ACM SIGCOMM 2011 Publicador: ACM SIGCOMM 2011
Tipo: info:eu-repo/semantics/article; acceptedVersion Formato: application/pdf
ENG
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The demo is focused on the implementation of ARP-Path (a.k.a. FastPath) bridges, a recently proposed concept for low latency bridges. ARP-Path Bridges rely on the race between broadcast ARP Request packets, to discover the minimum latency path to the destination host. Several implementations (in Omnet++, Linux, OpenFlow, NetFPGA) have shown that ARP-Path exhibits loop-freedom, does not block links, is fully transparent to hosts and neither needs a spanning tree protocol to prevent loops nor a link state protocol to obtain low latency paths. This demo compares our hardware implementation on NetFPGA to bridges running STP, showing that ARP-Path finds lower latency paths than STP.

A Small Data Center Network of ARP-Path Bridges made of Openflow Switches

Ibañez, Guillermo; Rojas, Elisa; Rivera, Diego; de Schuymer, Bart; Dietz, Thomas; Naous, Jad
Fonte: The 36th IEEE Conference on Local Computer Networks (LCN) Publicador: The 36th IEEE Conference on Local Computer Networks (LCN)
Tipo: info:eu-repo/semantics/article; submittedVersion Formato: application/pdf
ENG
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This demo shows, in a small data center demo network topology the ARP Path bridges functionality and robustness over varied platforms and their interoperability. ARP-Path bridges set up on-demand shortest paths between hosts using the standard ARP Request, but flooded over all links, to find the lowest latency path to the destination host. ARP Path is loop free, uses the standard Ethernet frame and compatible with hosts and routers.Data center demo network consists of ten ARP Path bridges. Eight bridges are implemented with standard Openflow switches (four NEC PF8800/PF5240 Open flow capable switches and four Soekris boxes running Open flow Switch implementation) and the other two are implemented on OpenWRT. A previous demo showed (in remote lab) the protocol operation over four NetFPGA boards executing Openflow[7]. Demo shows network operation with standard applications like video, demonstrating the protocol robustness, zero configuration, fast network reconfiguration upon link failures and after mobility of a host.. Implementations in Linux and Openflow show inherent robustness and fast reconfiguration. Additionally, information and video of the Sigcomm 2011 demo with implementation of ARP Path protocol on a network of four NetFPGA boards (pure hardware implementation) is also posted [8].

A Small Data Center Network of ARP-Path Bridges made of Openflow Switches

Ibáñez, Guillermo; Naous, J.; Rojas, Elisa; Rivera, Diego; De Schuymer, B.; Dietz, Thomas
Fonte: IEEE Publicador: IEEE
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/conferenceObject
Publicado em /10/2011 ENG
Relevância na Pesquisa
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This demo shows, in a small data center demo network topology the ARP Path bridges functionality and robustness over varied platforms and their interoperability. ARP-Path bridges set up on-demand shortest paths between hosts using the standard ARP Request, but flooded over all links, to find the lowest latency path to the destination host. ARP Path is loop free, uses the standard Ethernet frame and compatible with hosts and routers.Data center demo network consists of ten ARP Path bridges. Eight bridges are implemented with standard Openflow switches (four NEC PF8800/PF5240 Open flow capable switches and four Soekris boxes running Open flow Switch implementation) and the other two are implemented on OpenWRT. A previous demo showed (in remote lab) the protocol operation over four NetFPGA boards executing Openflow[7]. Demo shows network operation with standard applications like video, demonstrating the protocol robustness, zero configuration, fast network reconfiguration upon link failures and after mobility of a host.. Implementations in Linux and Openflow show inherent robustness and fast reconfiguration. Additionally, information and video of the Sigcomm 2011 demo with implementation of ARP Path protocol on a network of four NetFPGA boards (pure hardware implementation) is also posted [8].; This work is at: The 36th IEEE Conference on Local Computer Networks (LCN) took place 04/10/2011 - 07/10/2011 in Bonn (Germany). This web site to: http://www.ieeelcn.org/prior/LCN36/index.html

Aplicação da teoria da confiabilidade na obtenção de limites para o peso de veículos de carga em pontes de concreto; Development of truck weight limits for concrete bridges using reliability theory

Ferreira, Luciano Maldonado
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/05/2006 PT
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O aumento nos limites de pesos estabelecidos pela legislação brasileira e o surgimento de novas combinações de veículos de carga nos últimos anos tornam necessária a verificação da segurança estrutural das pontes quando submetidas ao tráfego real. Este trabalho verifica o desempenho das obras de arte sob jurisdição do DER-SP através do índice de confiabilidade 'beta' e obtém limites para o peso de caminhões de modo a não comprometer sua integridade estrutural. São consideradas as superestruturas das pontes em concreto armado ou protendido, classes 36 e 45. Verifica-se o estado limite último nas seções transversais mais solicitadas por momento fletor positivo e negativo. No caso de pontes em concreto protendido, acrescenta-se o estado limite de formação de fissuras. Para a representação do tráfego real, é desenvolvido um modelo de carregamento móvel com base em pesagens de caminhões efetuadas em rodovias do estado de São Paulo. Admite-se a presença simultânea de veículos sobre a ponte e diferentes relações entre seus pesos. Os parâmetros estatísticos da resistência são determinados através da técnica de Monte Carlo. Apresenta-se os limites de peso em forma de equações, denominadas ECPLs (equações comprimento-peso limite)...

Pontes de miocárdio em bovinos azebuados; Miocardial bridges in zebu bovines

Severino, Renato Souto; Caeneiro e Silva, Frederico Ozanan; Santos, André Luiz Quagliatto; Drummond, Sergio Salazar; Bombonato, Pedro Primo; Duran, Fernando Proni; Marçal, Amilton Vallandro
Fonte: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia Publicador: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; Formato: application/pdf
Publicado em 01/01/1997 POR
Relevância na Pesquisa
36.86%
Thirty hearts of males cattle from 30 to 50 months old were studied, in order to observe the frequency, width and localization of the myocardial bridges on the coronary arteries. Hearts had their coronary arteries injected with colored solution of Neoprene latex 450, what was followed by dissection. Myocardial bridges were observed in 100% of the hearts.They were multiple in56,6% of the cases. The width of those bridges ranged from 0.3 to 6.2 cm with an avarege of 1.62 cm. Bridges were most frequently found in the medium portion of the ventriculus.The most common site of myocardial bridges was the paraconal interventricular branch.; Estudou-se em 30 corações de bovinos azebuados, machos, com idade variando de 30 a 50 meses, a freqüência, a largura, a posição e a vasculotopia das pontes de miocárdio, mediante injeção das artérias coronárias com solução de Neoprene látex 450 e posterior dissecação. Os resultados indicam freqüência de 100% de corações com pontes e 56,6% das peças apresentaram pontes múltiplas. A largura das pontes variou de 0,3 cm a 6,2 cm com média de 1,62 cm e estas localizaram-se com maior freqüência na região média (36,8%) do ventrículo. O ramo interventricular paraconal foi o que apresentou maior número e freqüência de pontes.