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Leiria, Portugal

The Polytechnic Institute of Leiria is a public institution of Higher Education that offers courses of training on an Undergraduate Degree, Masters, Post-Graduate, Technology Specialization and Preparation Courses for Access to Higher Education level. It began its activity in 1980 and is present in the Leiria and West region through its five schools, divided in five campus, located in the cities of Leiria , Caldas da Rainha and Peniche . IPL offers Undergraduate e Master Degrees courses in the areas of: Art and Design, Law studies, Education and Communication, Engineering and Technology, Tourism and Health. Wikipedia.

Domingues A.,University of Lisbon | Santos H.,Polytechnic Institute of Leiria | Costa M.,University of Lisbon
Energy | Year: 2013

This study evaluates the vehicle exhaust WHR (waste heat recovery) potential using a RC (Rankine cycle ). To this end, both a RC thermodynamic model and a heat exchanger model have been developed. Both models use as input, experimental data obtained from a vehicle tested on a chassis dynamometer. The thermodynamic analysis was performed for water, R123 and R245fa and revealed the advantage of using water as the working fluid in applications of thermal recovery from exhaust gases of vehicles equipped with a spark-ignition engine. Moreover, the heat exchanger effectiveness for the organic working fluids R123 and R245fa is higher than that for the water and, consequently, they can also be considered appropriate for use in vehicle WHR applications through RCs when the exhaust gas temperatures are relatively low. For an ideal heat exchanger, the simulations revealed increases in the internal combustion engine thermal and vehicle mechanical efficiencies of 1.4%-3.52% and 10.16%-15.95%, respectively, while for a shell and tube heat exchanger, the simulations showed an increase of 0.85%-1.2% in the thermal efficiency and an increase of 2.64%-6.96% in the mechanical efficiency for an evaporating pressure of 2 MPa. The results confirm the advantages of using the thermal energy contained in the vehicle exhaust gases through RCs. Furthermore, the present analysis demonstrates that improved evaporator designs and appropriate expander devices allowing for higher evaporating pressures are required to obtain the maximum WHR potential from vehicle RC systems. © 2012 Elsevier Ltd. Source

Gameiro N.S.,Polytechnic Institute of Leiria | Gameiro N.S.,Telecommunications Institute of Portugal | Marques Cardoso A.J.,University of Beira Interior
IEEE Transactions on Industry Applications | Year: 2012

This paper presents a new fault diagnostic technique applied to switched reluctance motor drives, based on the analysis of the power converter supply current. A fault is detected when the measured amplitude of the dc bus current differs from its expected amplitude, assuming normal operating conditions. The information about phase currents amplitudes and the control commands of all power switches permit to easily estimate the amplitude of the power converter supply current, since an asymmetric bridge converter is used. Simulation and experimental results are presented. Open-and short-circuit fault occurrences in the converter power switches are considered and analyzed. The proposed technique can early detect these fault occurrences and can also identify the affected motor phase. In almost all situations, the faulty element is also identified. An early fault diagnosis, with an accurate fault identification, is of a paramount importance since it permits the early adoption of fault-tolerant procedures that minimize the fault impact on the machine operation. © 2011 IEEE. Source

Santos P.M.D.,Polytechnic Institute of Leiria | Julio E.N.B.S.,University of Lisbon
Engineering Structures | Year: 2012

Initially proposed in 1966, the " shear-friction theory" has been adopted in all design codes to analyse concrete-to-concrete interfaces. In the last decades, several improvements were suggested to take into account more influencing factors, to increase the accuracy and to enlarge the application field. The inclusion of the concrete strength and density and the consideration of the dowel action are examples of the proposed improvements.This paper presents a literature review on design expressions for shear-friction, chronologically ordered, describing proposals from the earliest research studies, precursors of the theory, until the most recent studies, incorporated in the newest fib Model Code. The most significant contributions are identified and a comparison between some of these design expressions is presented. Codes updates concerning shear-friction provisions are also identified in the literature review herein presented. © 2012 Elsevier Ltd. Source

da Silva F.J.,Polytechnic Institute of Leiria
Journal of integrative bioinformatics | Year: 2011

Multiple sequence alignment is one of the most recurrent assignments in Bioinformatics. This method allows organizing a set of molecular sequences in order to expose their similarities and their differences. Although exact methods exist for solving this problem, their use is limited by the computing demands which are necessary for exploring such a large and complex search space. Genetic Algorithms are adaptive search methods which perform well in large and complex spaces. Parallel Genetic Algorithms, not only increase the speed up of the search, but also improve its efficiency, presenting results that are better than those provided by the sum of several sequential Genetic Algorithms. Although these methods are often used to optimize a single objective, they can also be used in multidimensional domains, finding all possible tradeoffs among multiple conflicting objectives. Parallel AlineaGA is an Evolutionary Algorithm which uses a Parallel Genetic Algorithm for performing multiple sequence alignment. We now present the Parallel Niche Pareto AlineaGA, a multiobjective version of Parallel AlineaGA. We compare the performance of both versions using eight BAliBASE datasets. We also measure up the quality of the obtained solutions with the ones achieved by T-Coffee and ClustalW2, allowing us to observe that our algorithm reaches for better solutions in the majority of the datasets. Copyright 2011 The Author(s). Published by Journal of Integrative Bioinformatics. Source

Santos P.M.D.,Polytechnic Institute of Leiria | Julio E.N.B.S.,University of Lisbon
ACI Materials Journal | Year: 2011

The bond strength of concrete-to-concrete interfaces, of reinforced concrete (RC) members with parts cast at different ages, is highly influenced by the curing conditions. Therefore, the monolithic behavior is dependent on these conditions. Current design codes only consider: a) the concrete compressive strength; b) the normal stress at the interface; c) the amount of reinforcement crossing the interface; and d) the roughness of the substrate surface. Because the curing conditions of both substrate and added concrete are ignored, the influence of the differential shrinkage is neglected. The influence of the differential stiffness due to the mismatch between the Young's modulus of both materials is not considered either. This paper presents an experimental study conducted to assess the influence of differential shrinkage and stiffness on the bond strength of new-to-old concrete interfaces. Both parameters were shown to have a significant influence on the bond strength and failure mode of concrete-to-concrete interfaces. Copyright © 2011, American Concrete Intitute. All rights reserved. Source

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