Ferramentas para análise dinâmica e estrutural de um reboque de linha leve

Neste trabalho é desenvolvida uma metodologia de projeto para identificar as regiões críticas da estrutura de um reboque de linha leve sendo tracionado em pavimentos do tipo rodovia de baixa qualidade e estrada secundária de muito baixa qualidade. Para tanto, são levantados alguns dados experimentais da estrutura, necessários para a aproximação e simulação dinâmica de um modelo simplificado. A excitação da base é realizada por atuadores que simulam as oscilações verticais de um perfil de estrada, a qual é definida de acordo com os estudos realizados por Dodds e Robson (1973). Isto permite a determinação de um histórico de carregamentos das regiões da estrutura do chassi sob a ação das molas da suspensão. Em seguida, é gerado um modelo estrutural simplificado do reboque em elementos finitos, chamado de global, no qual são determinadas as regiões sob ação das maiores tensões. Tendo identificada a região mais crítica da estrutura, é criado um modelo local desta parte, onde se pode observar a distribuição de tensões com mais detalhe, permitindo a identificação dos pontos de concentração de tensões. Desta forma, com a aplicação do método de análise global-local é possível a obtenção de resultados detalhados quanto aos esforços da estrutura com um menor custo computacional.

Transport modelling: macro and micro simulation for the studied case of Funchal

The work done in this thesis attempts to demonstrate the importance of using models that can predict and represent the mobility of our society. To answer the proposed challenges two models were examined, the first corresponds to macro simulation with the intention of finding a solution to the frequency of the bus company Horários do Funchal, responsible for transport in the city of Funchal, and some surrounding areas. Where based on a simplified model of the city it was possible to increase the frequency of journeys getting an overall reduction in costs. The second model concerns the micro simulation of Avenida do Mar, where currently is being built a new roundabout (Praça da Autonomia), which connects with this avenue. Therefore it was proposed to study the impact on local traffic, and the implementation of new traffic lights for this purpose. Four possible situations in which was seen the possibility of increasing the number of lanes on the roundabout or the insertion of a bus lane were created. The results showed that having a roundabout with three lanes running is the best option because the waiting queues are minimal, and at environmental level this model will project fewer pollutants. Thus, this thesis presents two possible methods of urban planning. Transport modelling is an area that is under constant development, the global goal is to encourage more and more the use of these models, and as such it is important to have more people to devote themselves to studying new ways of addressing current problems, so that we can have more accurate models and increasing their credibility.

Modelos para análise e dimensionamento de painéis de alvenaria estrutural

The main objective of this thesis was the study of bracing panels of structural masonry, by applying the Finite Element Method and Strut and Tie Method. It was analyzed the following aspects: the effect of orthotropy on the behavior of the panels; distribution of horizontal forces between panels for buildings; comparison between Equivalent Frame and Finite Elements models; panels design with the Strut and Tie Method. The results showed that one should not disregard the orthotropy, otherwise this can lead to models stiffer than the real. Regarding the distribution of horizontal forces, showed that the disregard of lintels and shear deformation leads to significant differences in the simplified model. The results showed also that the models in Finite Element and Equivalent Frame exhibit similar behavior in respect to stiffness of panels and stress distribution over the sessions requested. It was discussing criteria for designing Strut and Tie Method models in one floor panels. Then, the theoretical strength these panels was compared with the rupture strength of panels tested in the literature. The theoretical maximum strength were always less than the rupture strength of the panels obtained in tests, due to the fact that the proposed model cannot represent the behavior of the masonry after the start of the panel cracking due to plasticization of the reinforcement

On the evection resonance and its connection to the stability of outer satellites

In terms of stability around the primary, it is widely known that the semimajor axis of the retrograde satellites is much larger than the corresponding semimajor axis of the prograde satellites. Usually this conclusion is obtained numerically, since precise analytical derivation is far from being easy, especially, in the case of two or more disturbers. Following the seminal idea that what is unstable in the restricted three-body problem is also unstable in the general N-body problem, we present a simplified model which allows us to derive interesting resonant configurations. These configurations are responsible for cumulative perturbations which can give birth to strong instability that may cause the ejection of the satellite. Then we obtain, analytically, approximate bounds of the stability of prograde and retrograde satellites. Although we recover quite well previous results of other authors, we comment very briefly some weakness of these bounds. Copyright (c) 2008 Tadashi Yokoyama et al.

ALGORITHM FOR PROBABILISTIC ANALYSIS of DISTRIBUTION SYSTEMS WITH DISTRIBUTED GENERATION

In this paper an efficient algorithm for probabilistic analysis of unbalanced three-phase weakly-meshed distribution systems is presented. This algorithm uses the technique of Two-Point Estimate Method for calculating the probabilistic behavior of the system random variables. Additionally, the deterministic analysis of the state variables is performed by means of a Compensation-Based Radial Load Flow (CBRLF). Such load flow efficiently exploits the topological characteristics of the network. To deal with distributed generation, a strategy to incorporate a simplified model of a generator in the CBRLF is proposed. Thus, depending on the type of control and generator operation conditions, the node with distributed generation can be modeled either as a PV or PQ node. To validate the efficiency of the proposed algorithm, the IEEE 37 bus test system is used. The probabilistic results are compared with those obtained using the Monte Carlo method.

Stress Analysis in Simulation Models With or Without Implant Threads Representation

Purpose: This study aimed to evaluate the influence of implants with or without threads representation on the outcome of a two-dimensional finite element (FE) analysis. Materials and Methods: Two-dimensional FE models that reproduced a frontal section of edentulous mandibular posterior bone were constructed using a standard crown/implant/screw system representation. To evaluate the effect of implant threads, two models were created: a model in which the implant threads were accurately simulated (precise model) and a model in which implants with a smooth surface (press-fit implant) were used (simplified model). An evaluation was performed on ANSYS software, in which a load of 133 N was applied at a 30-degree angulation and 2 mm off-axis from the long axis of the implant on the models, The Von Mises stresses were measured. Results: The precise model (1.45 MPa) showed higher maximum stress values than the simplified model (1.2 MPa). Whereas in the cortical bone, the stress values differed by about 36% (292.95 MPa for the precise model and 401.14 MPa for the simplified model), in trabecular bone (19.35 MPa and 20.35 MPa, respectively), the stress distribution and stress values were similar. Stress concentrations occurred around the implant neck and the implant apex. Conclusions: Considering implant and cortical bone analysis, remarkable differences in stress values were found between the models. Although the models showed different absolute stress values, the stress distribution was similar. INT J ORAL MAXILLOFAC IMPLANTS 2009;24:1040-1044

Kinetics of osmotic dehydration and air-drying of pumpkins (Cucurbita moschata)

Kinetics of osmotic dehydration (OD) and effects of sucrose impregnation on thermal air-drying of pumpkin slices were investigated. A simplified model based on the solution of Fick's Law was used to estimate effective diffusion coefficients during OD and air-drying. In order to take into account shrinkage, average and variable thicknesses were considered. Pumpkin slices were dehydrated in sucrose solutions (40%, 50% and 60%, w/w, 27 degrees C. The effective water diffusion coefficients were higher than the sucrose, and low diffusivity dependence with solution concentration was observed. Samples non-treated and pre-treated in 60% osmotic solutions during one hour were dried in a hot-air-dryer at 50 and 70 degrees C (2 m/s) until equilibrium was achieved. Pre-treatment enhanced mass transfer during air-drying. Great volume reduction was observed in pre and non-treated dried samples. Using variable thickness in the model diminished the relative deviations between predicted and experimental OD and drying data. (C) 2007 Elsevier Ltd. All rights reserved.

Nonlinear Lattice Within Supersymmetric Quantum Mechanics Formalism

In the last decades, the study of nonlinear one dimensional lattices has attracted much attention of the scientific community. One of these lattices is related to a simplified model for the DNA molecule, allowing to recover experimental results, such as the denaturation of DNA double helix. Inspired by this model we construct a Hamiltonian for a reflectionless potential through the Supersymmetric Quantum Mechanics formalism, SQM. Thermodynamical properties of such one dimensional lattice are evaluated aming possible biological applications.

Dynamics at infinity and other global dynamical aspects of Shimizu-Morioka equations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Search for supersymmetry in hadronic final states using M-T2 in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

O modelo keynesiano de James Meade

Este artigo reavalia o modelo simplificado da Teoria Geral de Keynes elaborado por James Meade e procura complementar alguns dos argumentos teóricos que Meade deixou apenas indicados. O artigo também responde às solicitações de Frisch a Meade, quanto à explicação do significado de estabilidade e à explicitação dos pressupostos que garantem suas conclusões. Além disso, apresenta alguns dos cálculos não desenvolvidos por Meade, e, quando necessário, suas devidas correções.

Modelling of fatigue crack growth following overloads

In variable-amplitude loading there are interaction effects between the loading history and the crack propagation rate. The most important of these effects is the retardation in the crack propagation, which may raise the life of the cracked structureconsiderably. The main objective of this research is to analyse and quantify the retardation of crack propagation in a thin plate of the high-resistance aluminium alloy 2024-T3, comparing the results obtained from the mathematical models proposed to account for the retardation effect. The specimens were tested under high-low loading sequences, for different crack sizes and overload ratios. A simplified model was developed, based on crack closure theory, that could represent the crack behaviour during retardation very well. © 1991.

Densification and residual stresses induced in glass surfaces by Vickers indentations

Images and profiles of Vickers impressions produced on as-received float-glass were obtained using atomic force microscopy (AFM). The images show that the impression edges undergo elastic recovery parallel to surface. The profiles made it possible to measure vertical elastic recovery, ev(r). For a 40 g nominal load, maximum penetration depth of indenter was (2.20 ± 0.03) μm, and recovery at the impression center was ev(0) = (0.98 ± 0.03) μm. Vertical elastic recovery was non-uniform along profiles. Permanent impressions produced resulted from glass mass displacement downward, producing an increase in glass density in impression vicinity, which is discussed in terms of changes in O-Si-O and Si-O-Si bond angles and Si-O bond length. Near impression edges, pileup was observed for which a simplified model is proposed taking into account the compaction and stresses near the impressions. © 2000 Elsevier Science B.V. All rights reserved.

An aproach for implementing knowledge management in small and medium companies in Brazil: A case study

The search for competitive advantage in a global environment must consider the use of tacit and explicit knowledge circulating inside companies. Differential factors can be easily replicated nowadays. Due to the great volume of knowledge and information, it is necessary to create a system that allows the management of important knowledge. Existing models for Knowledge Management are based on the reality at large companies. In Brazil, most of the companies are smaller ones. This work presents a simplified model to implement Knowledge Management in Small and Medium Companies in Brazil, based on a unique case study with limited scope. Despite some human and financial restrictions, Knowledge Management can help smaller companies, preserving organizational memory and increasing process efficiency. Observing a unique case prevented any generalization of the model. But the recommendations can be references to other companies, because projects like this must address the specific issues of each organization. The objective of this study is to introduce a simplified model for planning Knowledge Management at small companies in Brazil, considering their restrictions and also seeking to create a competitive advantage. Human aspects are very important in Knowledge Management, but that is not the focus of this study. The model was conceived presuming the participation of all people involved.