Intelligent cutting-off of pipes and bars

Traditionally, automatic cutting-off machines, of metallic pipes or bars, use a constant cutting velocity mode. This mode of operation, constant cutting velocity combined with different profiles of materials to be cut, exposes the cutting saw to variable cutting forces. Therefore, the cutting off machine is usually set for the worst expected conditions, otherwise excessive wear of the saw and machine will occur. Further, traditional cutting-off machines require the adjustment of the position of a limit switch in order to automatically detect when the cut of a piece has been completed. The aim of this paper is to study the application of control algorithms to the process of cutting-off metallic pipes or bars, with variable profiles, implemented in an industrial cutting-off machine, commercially available. The presented algorithms concern realtime cutting control and automatic detection of the cutting end. The algorithms are implemented in a low cost Programmable Logic Controller (PLC), allowing its use in industrial applications without significant increase on machine cost. All algorithms were developed having in mind safety issues relative to the operation of the cutting machine in order to prevent catastrophic failure. Also, all process related relevant parameters are monitored on a Personal Computer using OPC (Object Linking and Embedding – for Process Control)

Extending optimization algorithms to complex engineering problems

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Assessing the quality of the relation between scalarizing function parameters and solutions in multiobjective optimization

Different Multi-Objective Optimization Methods (MOOM) for solving Multi-Objective Optimization Problems (MOOP) have been suggested in the literature. These methods often comprise two stages (not necessarily sequential): i) the search for the Pareto-optimal set and ii) the selection of a single solution from this non-dominated set. Various studies comparing performance of particular aspects of these methods have been carried out. However, a theoretical support that changes on the preferences of a Decision Maker (DM) will be reflected in the same way on the solution of the MOOP given by the MOOM has not been presented. In this work a consistency measure to assess MOOM is proposed. It will used to compare the performance of different methods available in the literature. This study was performed using some benchmark test problems, with two criteria.This work was supported in part by the Portuguese Fundacao para a Ciencia e Tecnologia under grants: PTDC/GES/70168/2006 and SFRH/BD/22808/2005

Modelling of a Line-Start Permanent Magnet Synchronous Motor, Using Empirical Parameters

Line-started permanent magnet synchronous motors emerged in the market in response to strict efficiency goals. Despite being a synchronous motor, the rotor of a line-started permanent magnet synchronous motor contains a squirrel cage and, consequently, the behaviour under transient periods and/or faulty operation is not the same as for a conventional synchronous motor. In order to study this kind of electrical machine, it is proposed in this paper an equivalent circuit model and a set of experimental tests to extract the parameters of the equivalent circuit of a line-started permanent magnet synchronous motor. To validate the presented approach, a computer model of the machine, based on the obtained parameters, was developed, and the simulation results were compared with the experimental motor performance.SFRH/BSAB/118741/2016info:eu-repo/semantics/publishedVersio

Estudio cinético de la adsorción de Ni2+ desde solución acuosa sobre carbones activados obtenidos de residuos de tuza de maiz (Zea mays)

Se preparan carbones activados a partir de tuza de maíz por activación térmica con CO2 a diferentes tiempos de activación 2, 4 y 8 horas y se emplean en la adsorción de Ni2+ desde solución acuosa, comparando la capacidad de adsorción con la que se obtiene para el material natural que presenta propiedades adsorbentes.Los materiales carbonosos se caracterizan texturalmente por la adsorción de N2 y se obtienen valores de área superficial entre 327 y 1120 m2g-1, con una distribución de poro entre microporos y mesoporos, que favorece la adsorción del ion Ni2+.Se realiza la adsorción del ion metálico desde solución acuosa a un pH de 5 y los resultados experimentales de la adsorción se ajustan a los modelos de Freundlich y Langmuir, se presenta un mejor ajuste para el segundo modelo, con valores para la capacidad máxima de adsorción entre 32,88 y 43,65 mgg-1.Se determinó la adsorción del Ni2+ sobre los carbones activadosdesde solución acuosa, en función del tiempo, y se ajustaron los resultados de la adsorción para el estudio de la cinética por los modelos de seudo primer y seudo segundo orden; se observa que los datos cinéticos experimentales tienen mayor correlación con el modelo de seudo segundo orden.Se determinan entalpías de inmersión de los carbones activados en soluciones con diferentes concentraciones de Ni2+ y se obtienen resultados entre 11 y 39 Jg-1, que indican la variación de la entalpía con la presencia del ion metálico en la solución

Sistema de fabrico rápido de implantes ortopédicos

Este estudo teve como objectivo o desenvolvimento uma metodologia de fabrico rápido de implantes ortopédicos, em simultaneidade com a intervenção cirúrgica, considerando duas potenciais aplicações na área ortopédica: o fabrico de implantes anatomicamente adaptados e o fabrico de implantes para substituição de perdas ósseas. A inovação do trabalho desenvolvido consiste na obtenção in situ da geometria do implante, através da impressão directa de um material elastomérico (polivinilsiloxano) que permite obter com grande exactidão a geometria pretendida. Após digitalização do modelo obtido em material elastomérico, o implante final é fabricado por maquinagem recorrendo a um sistema de CAD/CAM dedicado. O implante após esterilização, pode ser colocado no paciente. O conceito foi desenvolvido com recurso a tecnologias disponíveis comercialmente e de baixo custo. O mesmo foi testado sob a forma de uma artroplastia da anca realizada in vivo numa ovelha. O acréscimo de tempo de cirurgia foi de 80 minutos sendo 40 directamente resultantes do processo de fabrico do implante. O sistema desenvolvido revelou-se eficiente no alcance dos objectivos propostos, possibilitando o fabrico de um implante durante um período de tempo perfeitamente compatível com o tempo de cirurgia.This study, aimed the development of a methodology for rapid manufacture of orthopedic implants simultaneously with the surgical intervention, considering two potential applications in the fields of orthopedics: the manufacture of anatomically adapted implants and implants for bone loss replacement. This work innovation consists on the capitation of the in situ geometry of the implant by direct capture of the shape using an elastomeric material (polyvinylsiloxane) which allows fine detail and great accuracy of the geometry. After scanning the elastomeric specimen, the implant is obtained by machining using a CNC milling machine programmed with a dedicated CAD/CAM system. After sterilization, the implant is able to be placed on the patient. The concept was developed using low cost technology and commercially available. The system has been tested in an in vivo hip arthroplasty performed on a sheep. The time increase of surgery was 80 minutes being 40 minutes the time of implant manufacturing. The system developed has been tested and the goals defined of the study achieved enabling the rapid manufacture of an implant in a time period compatible with the surgery time

Cell Wall Proteomics as a Means to Identify Target Genes to Improve Second‐Generation Biofuel Production

Second‐generation biofuels (B2G) generally uses residues composed of lignocellulosic materials to produce renewable energy (potentially up to 50%), without increasing the planted areas. However, the high cost of enzymes required for cell wall disassembly prior to the saccharification makes the B2G production more expensive yet, compared to the first‐generation biofuels. Designing plants with less lignin, a barrier to B2G production, or facilitating cell wall disassembly by searching for the plant mechanisms can be the way to obtain B2G feasibility. Therewith, plant cell wall proteomics provides valuable information concerning the main cell wall proteins (CWPs) involved in its biosynthesis and rearrangements. Essentially, two plants of the grass family have been studied: sugarcane as a crop amenable to second‐generation ethanol (E2G) production; and Brachypodium distachyon as a model plant amenable to genetic transformation. Cell wall proteomics has allowed the identification of numerous CWPs as well as their fine profiling in different organs and at various developmental stages. Proteins acting on carbohydrates, mostly glycosyl hydrolases, and oxidoreductases, including class III peroxidases and laccases, can be highlighted. Both kinds of CWPs are assumed to contribute to the remodelling of cell wall polysaccharides by enzymatic or non‐enzymatic mechanisms. CWPs present in growing organs could also be attractive candidates since they greatly contribute to cell wall plasticity

Effect of concentration of the diazoalcene molybdenum complex immobilized in ureasil matrix

The complex trans-[FMo(NNCHCHCHCH2CH3)(Ph2PCH2CH2PPh2)2][BPh4], was dispersed in a hybrid matrix synthesized by a sol-gel process. The host matrix of the so-called ureasil is a network of silica to which oligopolyoxyethylene chains [POE, (OCH2CH2)n] are grafted by means of urea cross-links. The free complex and sol-gel materials were characterized by thermal analysis (DSC), surface analysis (XPS) and spectroscopic methods (FT-IR and UV/Vis). The data gathered indicates that the molybdenum(IV) complex is immobilized in the host matrix, and it exhibits structural properties different from those of the free form. These differences could arise either from distortions caused by steric effects imposed by the structure of hybrid matrix or by interactions with the matrix. These materials shows potential applications in heterogeneous catalysis in mild conditions