Finite Element Analysis of Shear Versus Torsion Adhesive Strength Tests for Dental Resin Composites

Stress distributions in torsion and wire-loop shear tests were compared using three-dimensional (3-D) linear-elastic finite element method, in an attempt to predict the ideal conditions for testing adhesive strength of dental resin composites to dentin. The torsion test presented lower variability in stress concentration at the adhesive interface with changes in the proportion adhesive thickness/resin composite diameter, as well as lower variability with changes in the resin composite elastic modulus. Moreover, the torsion test eliminated variability from changes in loading distance, and reduced the cohesive fracture tendency in the dentin. The torsion test seems to be more appropriate than wire-loop shear test for testing the resin composite-tooth interface strength. (c) Koninklijke Brill NV, Leiden, 2009

The suitability of different FEA models for studying root fractures caused by wedge effect

Finite element analysis (FEA) utilizing models with different levels of complexity are found in the literature to study the tendency to vertical root fracture caused by post intrusion (""wedge effect""). The objective of this investigation was to verify if some simplifications used in bi-dimensional FEA models are acceptable regarding the analysis of stresses caused by wedge effect. Three plane strain (PS) and two axisymmtric (Axi) models were studied. One PS model represented the apical third of the root entirely, in dentin (PS-nG). The other models included gutta-percha in the apical third, and differed regarding dentin-post relationship: bonded (PS-B and Axi-B) or nonbonded (PS-nB and Axi-nB). Mesh discretization and material properties were similar for all cases. Maximum principal stress (sigma(max)) was analyzed as a response to a 165 N longitudinal load. Stress magnitude and orientation varied widely (PS-nG: 10.3 MPa; PS-B: 0.8 MPa; PS-nB: 10.4 MPa; Axi-13: 0.2 MPa, Axi-nB: 10.8 MPa). Axi-nB was the only model where all (sigma(max) vectors at the apical third were perpendicular to the model plane. Therefore, it is adequate to demonstrate the tendency to vertical root fractures caused by wedge effect. Axi-13 showed only part of the (sigma(max) perpendicular to the model plane while PS models showed sigma(max) on the model plane. In these models, sigma(max) orientation did not represent a situation where vertical root fracture would occur due to wedge effect. Adhesion between post and dentin significantly reduced (c) 2007 Wiley Periodicals, Inc.

Robust model-order reduction of complex biological processes

This paper addresses robust model-order reduction of a high dimensional nonlinear partial differential equation (PDE) model of a complex biological process. Based on a nonlinear, distributed parameter model of the same process which was validated against experimental data of an existing, pilot-scale BNR activated sludge plant, we developed a state-space model with 154 state variables in this work. A general algorithm for robustly reducing the nonlinear PDE model is presented and based on an investigation of five state-of-the-art model-order reduction techniques, we are able to reduce the original model to a model with only 30 states without incurring pronounced modelling errors. The Singular perturbation approximation balanced truncating technique is found to give the lowest modelling errors in low frequency ranges and hence is deemed most suitable for controller design and other real-time applications. (C) 2002 Elsevier Science Ltd. All rights reserved.

Protecção contra descargas atmosféricas: aplicação informática de identificação das vulnerabilidades das edificações e de apoio à concepção da protecção

A concepção de instalações eléctricas deve garantir condições de segurança para as pessoas e equipamentos. Para tal é exigida, quer por força de regulamentação ou de normalização, a instalação de dispositivos que garantam a detecção e a protecção contra os defeitos mais comuns nas instalações eléctricas como, por exemplo, as sobreintensidades e as sobretensões. Susceptíveis de criar sobretensões perigosas nas instalações eléctricas, as descargas atmosféricas podem ainda causar danos estruturais elevados, o que, em algumas actividades económicas, torna fundamental a implementação de medidas de protecção contra este fenómeno natural. A protecção contra descargas atmosféricas directas consiste em identificar as vulnerabilidades das estruturas e, nesses locais, implementar dispositivos de captura, direccionamento e escoamento da descarga atmosférica à terra, em condições de segurança. O presente trabalho, desenvolvido no âmbito da dissertação de Mestrado em Engenharia Electrotécnica, visa desenvolver e implementar uma ferramenta computacional, baseada em programas de desenho assistido por computador (CAD) de utilização corrente na área de projecto de arquitectura e de engenharia, que permita, no âmbito de normas internacionais, a análise e implementação de sistemas de protecção em edifícios contra descargas atmosféricas de uma forma rápida e expedita. Baseado num programa CAD 3D, que permite a modelização tridimensional das estruturas a proteger, a ferramenta desenvolvida tentará identificar as suas vulnerabilidades das estruturas às descargas atmosféricas directas, com o intuito de implementar as medidas de protecção mais adequadas do ponto de vista técnico económico. Prevê-se que a ferramenta resultante deste estudo, o Simulador do Modelo Electrogeométrico (SIMODEL), possibilite aos projectistas e particularmente aos alunos das unidades curriculares na área do projecto de instalações eléctricas da Área Departamental de Engenharia de Sistemas e Potencia e Automação (ADESPA) do ISEL, estudar e implementar sistemas de protecção contra descargas atmosféricas (SPDA) baseados na normalização internacional do CENELEC e da IEC, nomeadamente as normas da série 62305.

Optimization studies through simulation of a methanol/water/glycerol distillation column

This paper presents an optimization study of a distillation column for methanol and aqueous glycerol separation in a biodiesel production plant. Considering the available physical data of the column configuration, a steady state model was built for the column using Aspen-HYSYS as process simulator. Several sensitivity analysis were performed in order to better understand the relation between the variables of the distillation process. With the information obtained by the simulator, it is possible to define the best range for some operational variables that maintain composition of the desired product under specifications and choose operational conditions to minimize energy consumptions.

Designing next generation car washing machines with rotary brushes

Tese de Doutoramento - Leaders for Technical Industries (LTI) - MIT Portugal

Contribution of the evaluation strategy and the use of hearing protection for the uncertainty associated with occupational exposure to noise

Doctoral Thesis for PhD degree in Industrial and Systems Engineering

Using balanced scorecards to evaluate the data warehouse system utility

Dissertação de mestrado em Systems Engineering

Development of a model for occupational risk acceptance criteria definition in industrial settings

Doctoral Dissertation for PhD degree in Industrial and Systems Engineering

Modelação de processos num serviço de uma organização de ensino superior

Dissertação de mestrado integrado em Engenharia e Gestão Industrial

Catàleg de productes : ArtNet TFC .NET + AJAX

ArtNet és el treball final de carrera d'enginyeria tècnica de sistemes. La finalitat d'aquest projecte és desenvolupar una aplicació Web utilitzant la tecnologia .Net amb AJAX.

Vehicle WiFi

El projecte presenta el disseny d'un vehicle a motor elèctric construït sobre el sistema microcontrolador LPC1769 amb comunicacions sense fils via xarxes WiFi i detecció d'obstacles per sonar.

Solicitud de verificación de la titulación. Grado en Ingeniería de Sistemas de Telecomunicación por la Universitat Politècnica de Catalunya ‐ ETSETB

Solicitud de verificación de la titulaciónGrado en Ingeniería de Sistemas de Telecomunicación por la Universitat Politècnica de Catalunya ‐ ETSETBsegún el protocolo VERIFICA de la Agencia Nacional de Evaluación de la Calidad y Acreditación.

Solicitud de verificación de la titulación. Grado en Ingeniería de Sistemas Audiovisuales por la Universitat Politècnica de Catalunya ‐ ETSETB

Solicitud de verificación de la titulaciónGrado en Ingeniería de Sistemas Audiovisuales por la Universitat Politècnica de Catalunya ‐ ETSETB según el protocolo VERIFICA de la Agencia Nacional deEvaluación de la Calidad y Acreditación.

Semantiikan hyödyntäminen dokumenttienhallinnassa

Työn tavoitteena on etsiä asiakasyritykselle sähköteknisen dokumentoinnin hallintaan sopiva järjestelmäratkaisu vertailemalla insinööritoimistojen käyttämien suunnittelujärjestelmien ja yleisten dokumenttien hallintajärjestelmien soveltuvuutta asiakasympäristöön. Työssä tutkitaan sopivien metatietojen kuvaustapojen käyttökelpoisuutta sähköteknisen dokumentoinnin hallintaan esimerkkiprojektien avulla. Työn sisältö koostuu neljästä pääkohdasta. Ensimmäisessä jaksossa tarkastellaan dokumentin ominaisuuksia ja elinkaarta luonnista aktiivikäyttöön, arkistointiin ja hävitykseen. Samassa yhteydessä kerrotaan dokumenttienhallinnan perustehtävistä. Toisessa jaksossa käsitellään dokumenttien kuvailun tavoitteita, kuvailusuosituksia ja -standardeja sekä luonnollisen kielen käyttöä sisällönkuvailussa. Tarkastelukohteina suosituksista ovat W3C:n julkaisemat suositukset, Dublin Core, JHS 143 ja SFS-EN 82045. Kolmannessa jaksossa tarkastellaan teollisuuden dokumentoinnin ominaispiirteitä ja käyttötarkoitusta. Teollisuudessa on monia erilaisia järjestelmäympäristöjä tehtaan sisällä ja työssä kuvataan dokumenttienhallinnan integrointitarpeita muihin järjestelmiin. Viimeisessä jaksossa kuvaillaan erilaisia dokumentoinnin hallintaympäristöjä alkaen järeimmästä päästä tuotetiedon hallintajärjestelmistä siirtyen pienempiinsuunnittelujärjestelmiin ja lopuksi yleisiin dokumenttien hallintajärjestelmiin. Tässä osassa on myös luettelo ohjelmistotoimittajista. Työn tuloksena on laadittu valituista dokumenttityypeistä metatietokuvaukset kahden eri kuvaustavan (JHS 143 ja SFS-EN 82045) avulla ja on todettu molemmat kuvaustavat käyttökelpoisiksi sähköteknisen dokumentoinnin käsittelyyn.Nämä kuvaukset palvelevat asiakasta dokumenttienhallintaprojektin määrittelytyössä. Asiakkaalle on tehty myös vertailu sopivista järjestelmävaihtoehdoista hankintaa varten.