Página 1 dos resultados de 11 itens digitais encontrados em 0.009 segundos

Plasma confinement in tokamaks with robust torus

Martins, C. G L; De Carvalho, R. Egydio; Caldas, I. L.; Roberto, M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 957-962
ENG
Relevância na Pesquisa
35.84%
We present a non-linear symplectic map that describes the alterations of the magnetic field lines inside the tokamak plasma due to the presence of a robust torus (RT) at the plasma edge. This RT prevents the magnetic field lines from reaching the tokamak wall and reduces, in its vicinity, the islands and invariant curve destruction due to resonant perturbations. The map describes the equilibrium magnetic field lines perturbed by resonances created by ergodic magnetic limiters (EMLs). We present the results obtained for twist and non-twist mappings derived for monotonic and non-monotonic plasma current density radial profiles, respectively. Our results indicate that the RT implementation would decrease the field line transport at the tokamak plasma edge. © 2010 Elsevier B.V. All rights reserved.

An anisotropic linear elastic boundary element formulation for masonry wall analysis

Oliveira Neto, Luttgardes de; John Masia, Mark; Taguti, Yzumi; Carlos Rigitano, Antonio
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 434-440
ENG
Relevância na Pesquisa
46.05%
This work presents an application of a Boundary Element Method (BEM) formulation for anisotropic body analysis using isotropic fundamental solution. The anisotropy is considered by expressing a residual elastic tensor as the difference of the anisotropic and isotropic elastic tensors. Internal variables and cell discretization of the domain are considered. Masonry is a composite material consisting of bricks (masonry units), mortar and the bond between them and it is necessary to take account of anisotropy in this type of structure. The paper presents the formulation, the elastic tensor of the anisotropic medium properties and the algebraic procedure. Two examples are shown to validate the formulation and good agreement was obtained when comparing analytical and numerical results. Two further examples in which masonry walls were simulated, are used to demonstrate that the presented formulation shows close agreement between BE numerical results and different Finite Element (FE) models. © 2012 Elsevier Ltd.

A non-linear masonry infill macro-model to represent the global behaviour of buildings under cyclic loading

Rodrigues, H.; Varum, H.; Costa, A.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.2%
The presence of masonry infill walls in RC buildings is very common. However, and even today, in the design of new buildings and in the assessment of existing ones, these infill walls are usually considered as non-structural elements and their influence in the structural response is generally ignored. For horizontal loading, infill panels can drastically modify the response, attracting forces to parts of the structure that have not been designed to resist them. This paper presents an improved non-linear numerical simulation model for the influence of the masonry infill walls in the seismic behavior of structure. The model is implemented in the PORANL program. After the implementation and calibration of the proposed masonry model, a series of non-linear dynamic analyses of a building representative of Modern Architecture in Europe were carried out. The main objective was to investigate the behavior of this type of building, and any weakness under seismic loading. The building geometry and the dimensions of the RC elements and infill walls were set in the original project, and confirmed in the technical visits. The building under study has nine storeys and the structure is mainly composed of 12 plane frames oriented in the transversal direction. The building was analyzed with a simplified plane model...

Numerical model to account for the influence of infill masonry on the RC structures behaviour

Varum, H.; Rodrigues, H.; Costa, A.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
26.09%
It is a common misconception considers that masonry infill walls in structural RC buildings can only increase the overall lateral load capacity, and, therefore, must always be considered beneficial to seismic performance. Recent earthquakes have showed numerous examples of severe damages or collapses of buildings caused by structural response modification induced by the non-structural masonry partitions. From a state-of-the-art review of the available numerical models for the representation of the infill masonry behaviour in structural response, it was proposed an upgraded model. The proposed model is inspired on the equivalent bi-diagonal compression strut model, and considers the non-linear behaviour of the infill masonry subjected to cyclic loads. The model was implemented and calibrated in a non-linear dynamic computer code, VISUALANL. In this paper, it is presented the proposed model and the results of the calibration analyses are briefly introduced and discussed.

Reabilitação de uma casa do século XIX, de Felgueiras: caracterização, diagnóstico das anomalias construtivas e bases para o projecto de restauro e reabilitação

Sousa, Dinis Passos de
Fonte: Universidade de Trás-os-Montes e Alto Douro Publicador: Universidade de Trás-os-Montes e Alto Douro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
15.95%
Dissertação de Mestrado em Engenharia Civil; São inúmeros os edifícios anteriores ao séc. XIX no nosso país. Muitos são abandonados, deixando este património à mercê dos diversos agentes de deterioração. Deve ser rapidamente incutido o sentido de manutenção e conservação dos edifícios antigos com valor patrimonial, correntes e monumentais, da paisagem rural e da salvaguarda do património rural edificado, através de políticas patrimoniais e de incentivos múltiplos. Esta dissertação pretende fundamentalmente estudar as técnicas pouco intrusivas e não destrutivas de inspecção e exame do estado de conservação de edifícios antigos, com base nos princípios e critérios de conservação, reabilitação e restauro de edifícios históricos, nas principais cartas e convenções internacionais de salvaguarda do património cultural, não esquecendo as exigências actuais de conforto e habitabilidade. Com essa finalidade, foi seleccionado um edifício do séc. XIX situado em de Felgueiras, para caso de estudo. Em primeiro lugar foi feito um Enquadramento Físico e Humano da zona onde se insere o edifício estudado, sendo estudadas algumas características da região. Após esse estudo, foi realizada a Caracterização Arquitectónica. Neste capítulo...

Self-assembly of the plant cell wall requires an extensin scaffold

Cannon, Maura C.; Terneus, Kimberly; Hall, Qi; Tan, Li; Wang, Yumei; Wegenhart, Benjamin L.; Chen, Liwei; Lamport, Derek T. A.; Chen, Yuning; Kieliszewski, Marcia J.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
15.84%
Cytokinesis partitions the cell by a cleavage furrow in animals but by a new cross wall in plants. How this new wall assembles at the molecular level and connects with the mother cell wall remains unclear. A lethal Arabidopsis embryogenesis mutant designated root-, shoot-, hypocotyl-defective (rsh) provides some clues: RSH encodes extensin AtEXT3, a structural glycoprotein located in the nascent cross wall or “cell plate” and also in mature cell walls. Here we report that electron micrographs of rsh mutant cells lacking RSH extensin correspond to a wall phenotype typified by incomplete cross wall assembly. Biochemical characterization of the purified RSH glycoprotein isolated from wild-type Arabidopsis cell cultures confirmed its identity as AtEXT3: a (hydroxy)proline-rich glyco protein comprising 11 identical amphiphilic peptide repeats with a 28-residue periodicity: SOOOOKKHYVYKSOOOOVKHYSOOOVYH (O = Hyp), each repeat containing a hydrophobic isodityrosine cross-link motif (YVY, underlined). Atomic force microscopy of RSH glycoprotein imaged its propensity for self-assembly into a dendritic scaffold. Extensin peroxidase catalyzed in vitro formation of insoluble RSH gels with concomitant tyrosine cross-linking, hence this likelihood in muro. We conclude that self-assembling amphiphiles of lysine-rich RSH extensin form positively charged scaffolds in the cell plate. These react with negatively charged pectin to create an extensin pectate coacervate that may template further orderly deposition of the new cross wall at cytokinesis.

In-field simulated seismic testing of as-built and retrofitted unreinforced masonry partition walls of the William Weir house in Wellington

Derakhshan, H.; Dizhur, D.; Lumantarna, R.; Cuthbert, J.; Griffith, M.; Ingham, J.
Fonte: New Zealand Structural Engineering Society Publicador: New Zealand Structural Engineering Society
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
36.3%
Unreinforced masonry (URM) partition walls of William Weir House in Wellington were subjected to out-of-plane forces to investigate the as-built wall characteristic behaviour. The lateral load resisting system of the 1932 reinforced concrete building was scheduled to undergo seismic strengthening, and due to the absence of reliable wall out-of-plane assessment data, consulting engineers adopted an experimental proof-testing approach. A team of student researchers from the University of Auckland tested four URM partition walls by subjecting the walls to out-of-plane uniform pressure applied by means of a system of airbags. The testing included two mid-storey and two top-storey URM partitions, which had developed prior minor structural cracks. The full-scale in-situ testing confirmed that the precracked partitions had sufficient strength to resist the current New Zealand seismic demand, and the experimental programme resulted in substantial financial benefits for the client as none of the walls were identified as demolition or strengthening candidates. In addition to the as-built out-of-plane tests, two tests were conducted on partition walls retrofitted using near surface- mounted (NSM) fibre-reinforced polymer (FRP) strips. The results of the as-built and the retrofitted wall testing are reported...

Analysis of the susceptibility of infilling masonry walls to crack due to vertical deformation of concrete structures

Rui Miguel Sousa; Hipólito Sousa
Fonte: Universidade do Porto Publicador: Universidade do Porto
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.17%
In this paper a numerical study is presented to evaluate the masonry partitions walls susceptibility to crack due to vertical deformation of concrete structures. Common solutions used in Portuguese buildings for structural systems and non-structural partition walls were analysed in this study.The numerical study was based on a 3D FEM macro models. Two types of simulations were performed. The first type was a simulation of a masonry deep beam subjected to vertical displacements, where experimental results obtained from tests were used to calibrate a non-linear constitutive model. The second type was the simulation of a representative part of a building concrete structure, partially filled with masonry partition walls, subjected to design loadings and creep effects. The objective of these simulations was to evaluate the partition walls susceptibility to crack by modifying some properties of these walls, and also to evaluate, as close as possible, the mechanical behaviour of partition walls affected by the deformation of concrete structures with creep effects.

Transport and Deposition of Plasma-Sputtered Platinum Atoms: Comparison Between Experiments and Simulation

Caillard, A.; Charles, Christine; Boswell, Roderick; Brault, Pascal
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.84%
The deposition of platinum atoms by argon plasma sputtering has been simulated by using a 3-D Monte Carlo simulation called Sputtered Particles Transport in Gas, which provides spatial and energy distributions of the Pt atoms impinging on the substrate an

Second-harmonic aberration correction

Kaupang, H; Varslot, Trond; Masoy, Svein-Erik
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
Relevância na Pesquisa
35.95%
A simulation study is performed to present results concerning 3D aberration correction for harmonic imaging. Two different correction schemes (a pure time-delay correction and a time-delay and amplitude correction) are employed along with estimation based

Gravitational Oscillators: Bouncing Balls, Rocking Beams, and Spinning Discs

Fletcher, Neville
Fonte: Australian Acoustical Society Publicador: Australian Acoustical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.95%
When an object is constrained to lie in a half-space bounded by a rigid horizontal wall, it will fall against this wall under the influence of gravity and then rebound in some way so as to execute oscillations which will gradually decay as energy is lost