Numerical modeling of wave soldering in PCB

Manufacturing of electronic boards (commonly referred as PCB) is a highly automated process that requires an accurate control of the various processing variables. Amongst the soldering processes, wave soldering is one of the most often used. In this, the various electronic components are provisionally inserted onto the PCB, and a low velocity jet of melted solder is directed to the moving board. Due to capillarity effects the solder adheres to the component/board interface and the process is completed. This methodology is most often used for small components. The adjusting of the operating parameters (solder nozzle orientation and velocity) is often carried out on a trial and error basis resulting in a time consuming process that is at odds with the increasing demand for smaller production series that the electronics industry is faced with. In addition the number of defects (mostly from missing components that are washed away by the impacting jet) is more likely to occur when thinner substrates are used in the PCB manufacturing. The present paper describes the application of a Computational Fluid Dynamics model to describe the interaction of the solder jet with the PCB and the integrated circuits. The model includes the conservation equations for mass, momentum and energy in a transient time frame. The jet and surrounding ambient atmosphere are modeled as two separate fluids and the interface is tracked by a VOF model. By adjusting the computational mesh refinement the interface is captured with accuracy. The drag forces occurring in the various components are computed from the pressure data field. The model allows the optimization of the wave operating parameters as a function of the component type of and its layout in the PCB

Projecto “Conservação, estudo, valorização e divulgação do complexo mineiro antigo do vale superior do rio Terva, Boticas" : trabalhos arqueológicos PAVT 2011 : levantamentos topográficos, prospecção e sondagens arqueológicas : relatório final

As ações desenvolvidas contaram com a participação de uma equipa permanente, composta por Luís Fontes, Mafalda Alves e Carla Martins, aos quais se juntaram, em colaborações pontuais, os arqueólogos do município de Boticas, Bruno Delfim e Helena Gonçalves. A assessoria científica para os estudos paleoambientais e geomorfológicos foi dada por José Luíz Meireles. Daremos conta, neste relatório, dos resultados obtidos nas várias ações empreendidas no âmbito desta fase de trabalhos

Projeto de investigação plurianual em arqueologia: Castro de Sapelos

O presente relatório enquadra-se na execução do Projeto PoPaTERVA 2013-2016, um projeto PIPA aprovado pela DGPC em 2013 (oficio nº 06922, de 04-07-13. Ref. 2013/1 (169) CS 875795), da responsabilidade de Luís Fernando de Oliveira Fontes/Unidade de Arqueologia da Universidade do Minho. No ano de 2015 deu-se continuidade às investigações decorrentes da implementação do projeto referido anteriormente, prosseguindo-se com o estudo de pormenor do Castro de Sapelos iniciado já no ano de 2014, nomeadamente com o levantamento topográfico de toda a área ocupada pelo povoado e com duas sondagens de diagnóstico. Os trabalhos arqueológicos foram iniciados a 28 de Setembro e terminaram no mês de Novembro.info:eu-repo/semantics/publishedVersio

Povoamento e paisagens no Vale Superior do Rio Terva, Boticas: projecto de investigação plurianual em arqueologia (PoPaTERVA 2013-2016): trabalhos arqueológicos no Castro de Sapelos: relatório 2014

O presente relatório enquadra-se na execução do Projeto PoPaTERVA 2013-2016, um projeto PIPA aprovado pela DGPC em 2013 (oficio nº 06922, de 04-07-13. Ref. 2013/1 (169) CS 875795). Para o corrente ano de 2014 pretendemos dar continuidade às investigações decorrentes da implementação do projeto referido anteriormente, iniciando assim o estudo em pormenor do Castro de Sapelos. Os trabalhos arqueológicos foram iniciados a 1 de Julho e terminaram no mês de Dezembro, contaram com a participação de 4 jovens voluntários do programa municipal Boticas Mexe

Povoamento e paisagens no Vale Superior do Rio Terva, Boticas: projecto de investigação plurianual em arqueologia (PoPaTERVA 2013-2016): trabalhos arqueológicos no povoado das Batocas: relatório 2013-2014

O relatório que se apresenta respeita aos trabalhos arqueológicos desenvolvidos entre 2013 e 2014, inscritos no Projeto de Investigação Plurianual de Arqueologia (adiante PIPA) “Povoamento e Paisagens no Vale Superior do Rio Terva, Boticas – PoPaTERVA 2013-2016”, oportunamente aprovado pela Direção Geral do Património Cultural (DGPC: ofício n.º 2013/1 (169) CS: 875795 informação n.º 1704/DBC/2013). O projeto Povoamento e Paisagens no Vale Superior do Rio Terva, Boticas/ PoPaTERVA surge na sequência da conclusão do projeto de Conservação, Estudo, Valorização e Divulgação do Complexo Mineiro Antigo do Vale Superior do Rio Terva, Boticas, concebido em 2006 pela UAUM e executado entre 2010 e 2012 no âmbito de protocolo estabelecido com a Câmara Municipal de Boticas. Desta primeira ação de investigação resultou a classificação do Complexo Mineiro Antigo do Vale Superior do Rio Terva como Sítio de Interesse Público, promulgado pela Portaria n.º 386/2013 (DR, 2.º Série, n.º 115 de 18 de Junho de 2013 – ver Apêndice 7.1.2)

Experimental and simulation results of a current-source three-phase shunt active power filter using periodic-sampling

In this paper are presented experimental and simulation results of a Current-Source Three-Phase Shunt Active Power Filter, during its operation to compensate the currents a low power factor load and a nonlinear load. The Shunt Active Power Filter controller, described in detail along the paper, relies in the p-q Theory to generate the reference compensation currents and to regulate the DC-link inductor current. The regulation of the DC-link inductor current is done consuming sinusoidal currents in phase with the system voltages. The performance and the dynamic behavior of the Shunt Active Power Filter using Periodic Sampling Modulation Technique was assessed first through several computer simulations, and then through the analysis of experimental results obtained with a developed laboratory prototype. Thereby, in this paper are presented several obtained results that show the correct operation of a Current-Source Three-Phase Shunt Active Power Filter using the Periodic Sampling Modulation Technique.Fundação para a Ciência e a Tecnologia (FCT

A simplified methodology for parameters measurement of an axial flux permanent magnet motor without neutral point

The recent developments in the area of electric vehicles resulted in the growth of the interest for Axial Flux Permanent Magnet Motors, mainly because of their high power density. For the design of the motor drive it is of extreme importance to have the motor parameters, although many times the manufacturers do not provide them. To overcome this problem, in this paper is presented a methodology to obtain the parameters of this type of motor, in order to make possible the implementation of the d-q model. In synchronous motors with permanent magnets the inductance changes with the rotor position, so the d-q model is used to simplify the analysis and to get a better understanding of the motor parameters. Thus, this paper presents the d-q model of an axial flux permanent magnet synchronous motor with two external stators and one internal rotor.FEDER Funds - Operational Programme for Competitiveness Factors (COMPETE)Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-EEL/104569/2008, MIT-PT/EDAM-SMS/0030/200

Smart charging system of the electric vehicle CEPIUM

In this paper is presented the development of a smart batteries charging system for the Electric Vehicle (EV) CEPIUM, aiming the integration of EVs in the future Smart Grids. The main features of the developed charging system are the mitigation of the power quality degradation and the bidirectional operation, as Grid-to-Vehicle (G2V) and as Vehicle-to-Grid (V2G). The batteries charging process is controlled by an appropriate control algorithm, aiming to preserve the batteries lifespan. During the charging process (G2V), the consumed current is sinusoidal and the power factor is unitary. Along the discharging process (V2G), when the equipment allows delivering back to the electrical power grid part of the energy stored in the batteries, the current is also sinusoidal.FEDER Funds - Operational Programme for Competitiveness Factors (COMPETE)Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-EEL/104569/2008, MITPT/ EDAM-SMS/0030/2008

The impact of poor power quality in solar photovoltaic microgeneration: technical problems and losses of revenue

This paper presents a critical and quantitative analysis of the influence of the Power Quality in grid connected solar photovoltaic microgeneration installations. First are introduced the main regulations and legislation related with the solar photovoltaic microgeneration, in Portugal and Europe. Next are presented Power Quality monitoring results obtained from two residential solar photovoltaic installations located in the north of Portugal, and is explained how the Power Quality events affect the operation of these installations. Afterwards, it is described a methodology to estimate the energy production losses and the impact in the revenue caused by the abnormal operation of the electrical installation. This is done by comparing the amount of energy that was injected into the power grid with the theoretical value of energy that could be injected in normal conditions. The performed analysis shows that Power Quality severally affects the solar photovoltaic installations operation. The losses of revenue in the two monitored installations M1 and M2 are estimated in about 27% and 22%, respectively.CT - Fundação para a Ciência e Tecnologia within scope of the project : PEst- UID/CEC/00319/2013