Characterization and performance analysis of a VDFLL GNSS receiver architecture

A non-coherent vector delay/frequency-locked loop architecture for GNSS receivers is proposed. Two dynamics models are considered: PV (position and velocity) and PVA (position, velocity, and acceleration). In contrast with other vector architectures, the proposed approach does not require the estimation of signals amplitudes. Only coarse estimates of the carrier-to-noise ratios are necessary.

Impact of different moodle course designs on students? Performance

This work describes the impact of different teachers’ approaches in using Moodle, for supporting their courses, at the Polytechnic of Porto - School of Engineering. The study covers five different courses, from different degrees and different years, and includes a number of Moodle resources especially supporting laboratory classes. These and other active resources are particularly analyzed in order to evaluate students’ adherence to them. One particular course includes a number of remote experiments, made available through VISIR (Virtual Instrument Systems in Reality) and directly accessible through links included in the Moodle course page. The collected data have been correlated with students’ classifications in the lab component and in the exam, each one weighting 50% of their final marks. This analysis benefited from the existence of different teachers’ approaches, which resulted in a diversity of Moodle-supported environments. Conclusions point to the existence of a positive correlation factor between the number of Moodle accesses and the final exam grade, although the quality of the resources made available by the teachers seems to be preponderant over its quantity. In addition, different students perspectives were found regarding active resources: while some seem to encourage students to participate (for instance online quiz or online reports), others, more demanding, are unable to stimulate the majority of them.

Student performance analysis under different moodle course designs

This work extends a recent comparative study covering four different courses lectured at the Polytechnic of Porto - School of Engineering, in respect to the usage of a particular Learning Management System, i.e. Moodle, and its impact on students' results. A fifth course, which includes a number of resources especially supporting laboratory classes, is now added to the analysis. This particular course includes a number of remote experiments, made available through VISIR (Virtual Instrument Systems in Reality) and directly accessible through links included in the Moodle course page. We have analyzed the students' behavior in following these links and in effectively running experiments in VISIR (and also using other lab related resources, in Moodle). This data have been correlated with students' classifications in the lab component and in the exam, each one weighting 50% of their final marks. We aimed to compare students' performance in a richly Moodle-supported environment (with lab component) and in a poorly Moodle-supported environment (with only theoretical component). This question followed from conclusions drawn in the above referred comparative study, where it was shown that even though a positive correlation factor existed between the number of Moodle accesses and the final exam grade obtained by each student, its explanation behind was not straightforward, as the quality of the resources was preponderant over its quantity.

Marx-Type solid-state bipolar modulator topologies: Performance comparison

The operation of generalized Marx-type solid-state bipolar modulators is discussed and compared with simplified Marx-derived circuits, to evaluate their capability to deal with various load conditions. A comparative analysis on the number of switches per cell, fiber optic trigger count, losses, and switch hold-off voltages has been made. A circuit topology is obtained as a compromise in terms of operating performance, trigger simplicity, and switching losses. A five-stage laboratory prototype of this circuit has been assembled using 1200 V insulated gate bipolar transistors (IGBTs) and diodes, operating with 1000 V dc input voltage and 1 kHz frequency, giving 5 kV bipolar pulses, with 2.5 mu s pulse width and 5 mu s relaxation time into resistive, capacitive, and inductive loads.

A construção do desenvolvimento profissional dos professores

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ciências da Educação, especialidade Supervisão em Educação

High-performance flexible hybrid field-effect transistors based on cellulose fiber paper

IEEE Electron Device Letters, VOL. 29, NO. 9,

Performance of fractional PID algorithms controlling nonlinear systems with saturation and backlash phenomena

The development of fractional-order controllers is currently one of the most promising fields of research. However, most of the work in this area addresses the case of linear systems. This paper reports on the analysis of fractional-order control of nonlinear systems. The performance of discrete fractional-order PID controllers in the presence of several nonlinearities is discussed. Some results are provided that indicate the superior robustness of such algorithms.

The impact of national cultures on international marketing strategy and subsidiary performance of portuguese SME’s

The dynamic of the international business and its multidimensional nature requires the understanding of the complexities of different contexts dictated by cultural differences between countries. The purpose of this paper is to study, in depth howsmall and medium-sized companies develop their international marketing mix strategy in their overseas subsidiaries. We use the theoretical construct of Hofstede (1980, 1991) in the dimensions of Power Distance (PD), Uncertainty Avoidance (UA), Individualism (IND), Masculinity (MASC) and Long-Term Orientation (LTO) to assess the cross cultural differences between countries and the business practices to analyze the adaptation or standardization of the international marketing mix strategy of foreign Portuguese subsidiaries. Ourstudy uses an exploratoryand qualitative methodology. We conducted semi-structured interviews in order to achieve a good understanding ofinternational marketing mix strategy of four companies from different sectors. Our results show that the national cultural differences have great influence in the marketing strategy of the subsidiary. The business practices adjustments in the subsidiary company that proved to be necessary conditions for their performance are conducted by the products augmented offerings concerning the characteristics of the product, design and brand name in order to meet the requirements and specificities of the host country of the subsidiary.

A case study on the eco-efficiency performance of a composite processing industry: evaluation and quantification of potential improvements

In this study, an attempt was made in order to measure and evaluate the eco-efficiency performance of a pultruded composite processing company. For this purpose the recommendations of World Business Council for Sustainable Development (WCSD) and the directives of ISO 14301 standard were followed and applied. The main general indicators of eco-efficiency, as well as the specific indicators, were defined and determined. With basis on indicators’ figures, the value profile, the environmental profile, and the pertinent eco-efficiency ratios were established and analyzed. In order to evaluate potential improvements on company eco-performance, new indicators values and eco-efficiency ratios were estimated taking into account the implementation of new proceedings and procedures, at both upstream and downstream of the production process, namely: i) Adoption of a new heating system for pultrusion die-tool in the manufacturing process, more effective and with minor heat losses; ii) Recycling approach, with partial waste reuse of scrap material derived from manufacturing, cutting and assembly processes of GFRP profiles. These features lead to significant improvements on the sequent assessed eco-efficiency ratios of the present case study, yielding to a more sustainable product and manufacturing process of pultruded GFRP profiles.

Gestão de instalações eléctricas para optimização do desempenho, eficiência e qualidade de energia em grandes edifícios com integração de Miniprodução

As alterações climáticas e as emissões de CO2 são questões que suscitam a nível internacional e nacional o desenvolvimento de estratégias que atenuem os seus impactes. A Eficiência Energética (EE) é essencial para que num futuro próximo não haja impactes significativos no meio ambiente devido a elevado e ineficiente consumo energético. A União Europeia (UE) e Portugal têm desenvolvido políticas e programas que estimulam a eficiência energética, bem como a diminuição de gases com efeito de estufa (GEE) e a promoção da utilização de fontes de energia renovável. Por outro lado vivemos numa sociedade que passa cerca de 80% do seu tempo em edifícios e, nestes, é consumida 40% da energia mundial. Com uma dependência energética superior a 80%, Portugal tem vindo a apostar, nos últimos anos, em fontes de energia renovável. Esta aposta serve como substituição de fontes, mas não leva directamente à redução de consumos. A redução da factura de energia só pode ser atingida com uma maior eficiência energética e melhores práticas de gestão de energia em edifícios, transportes e industria. Esta dissertação centra-se especificamente num conjunto de edifícios públicos, património municipal da autarquia de Matosinhos, cujo modelo de fornecimento da energia eléctrica é passível de análise crítica no sentido de uma optimização radical ao nível da concepção da rede e exploração, com consequente redução de custos ao nível da facturação. Esta nova metodologia de exploração e gestão de sistemas eléctricos incidirá na criação de um “campus” energético autárquico resultante do novo layout da rede e respectivo fornecimento de energia a partir da rede de distribuição pública. O estudo permitirá fornecer ferramentas fundamentais para a gestão municipal e empresarial ao nível da sustentabilidade energética nos edifícios públicos com abrangência aos serviços empresariais. De referir que a gestão das instalações eléctricas para optimização do desempenho, eficiência e qualidade de energia é aplicável aos 308 municípios nacionais com relevância para as empresas que apresentam consumos significativos nos seus edifícios. Enquanto funcionário da Câmara Municipal de Matosinhos, este município foi uma escolha natural como referência, na análise da relação existente entre a administração local e a gestão da energia. Para ajudar à análise foi efectuado um benchmarketing a cinco edifícios municipais: Edifício dos Paços do Concelho, Biblioteca Municipal Florbela Espanca, Palacete Visconde Trevões, ex-Edifício dos SMAS e Edifício do ex-Tribunal, visando potenciar a correcta gestão de energia destes edifícios por parte das entidades que os gerem, perante novas oportunidades de melhoria e soluções encontradas. Como contributo às metas impostas pela Directiva 2009/28/CE para 2020, a qual prevê uma redução de 20% no consumo final de energia através da eficiência energética, a incorporação de 20% de energia renovável no consumo energético global e a consequente redução em 20% da emissão de GEE, é apresentado um estudo ao nível de um parque fotovoltaico com a componente técnica e económica.

Effect of fungal colonization on mechanical performance of cork

The industrialization of traditional processes relies on the scientific ability to understand the empirical evidence associated with traditional knowledge. Cork manufacturing includes one operation known as stabilization, where humid cork slabs are extensively colonized by fungi. The implications of fungal growth on the chemical quality of cork through the analysis of putative fungal metabolites have already been investigated. However, the effect of fungal growth on the mechanical properties of cork remains unexplored. This study investigated the effect of cork colonization on the integrity of the cork cell walls and their mechanical performance. Fungal colonization of cork by Chrysonilia sitophila, Mucor plumbeus Penicillium glabrum, P. olsonii, and Trichoderma longibrachiatum was investigated by microscopy. Growth occurred primarily on the surface of the cork pieces, but mycelium extended deeper into the cork layers, mostly via lenticular channels and by hyphal penetration of the cork cell wall. In this first report on cork decay in which specific correlation between fungal colonization and mechanical proprieties of the cork has been investigated, all colonizing fungi except C. sitophila, reduced cork strength, markedly altering its viscoelastic behaviour and reducing its Young’s modulus.

Space-time monitoring of prescribed burnt soils performance – an effective tool for forest management

Among the most important measures to prevent wild forest fires is the use of prescribed and controlled burning actions in order to reduce the availability of fuel mass. However, the impact of these activities on soil physical and chemical properties varies according to the type of both soil and vegetation and is not fully understood. Therefore, soil monitoring campaigns are often used to measure these impacts. In this paper we have successfully used three statistical data treatments - the Kolmogorov-Smirnov test followed by the ANOVA and the Kruskall-Wallis tests – to investigate the variability among the soil pH, soil moisture, soil organic matter and soil iron variables for different monitoring times and sampling procedures.

Peroxidase antibody test for mucocutaneous leishmaniasis serology performance indexes and comparison with a fluorescent antibody test: Comparação com o desempenho da reação de imunofluorescência

Performance indexes of the peroxidase antibody test were compared to that of the fluorescent antibody test. The peroxidase antibody test had a statistically higher sensitivity and negative predictive value and a higher efficiency than the fluorescent antibody test but its specificity and positive predictive value were within the 95% confidence limits for the values found for the fluorescent antibody test. Such differences did not change when Chagas' disease and visceral leishmaniasis sera were included in index calculations. Statistical analysis showed that the two tests have a substantial degree of agreement but the immunofluorescent test had a specificity index and a positive predictive value equal to 100.0% when Chagas' disease and visceral leishmaniasis sera were not included in the calculations of the performance index; in this instance, a positive test result equals a disclosure of the disease attribute due to the inexistence of false positive results. The enzyme/ protein ratio of the peroxidase conjugate, resulting in heavy or light-labeled conjugates may pose technical problems to its use in serology tests.

Practical software improve design and performance of a randomly packed air stripping column for removing volatile organic compounds from water

STRIPPING is a software application developed for the automatic design of a randomly packing column where the transfer of volatile organic compounds (VOCs) from water to air can be performed and to simulate it’s behaviour in a steady-state. This software completely purges any need of experimental work for the selection of diameter of the column, and allows a choice, a priori, of the most convenient hydraulic regime for this type of operation. It also allows the operator to choose the model used for the calculation of some parameters, namely between the Eckert/Robbins model and the Billet model for estimating the pressure drop of the gaseous phase, and between the Billet and Onda/Djebbar’s models for the mass transfer. Illustrations of the graphical interface offered are presented.

Performance management in a family business: a case study

This research, still at an early stage, and then presented in a poster format, intended to explain the management of organizational performance of a family business in the succession process using the case study method. The scripts for semi-structured interviews that will apply to managers, owners and other workers who are deemed suitable for the investigation, which include relatives of the owners of the company are being developed. For this work the model of organizational performance management developed by David Otley in 1999 [1], consisting of five questions that seek to explain the existing performance management in any organization is utilized.