Dimensionless analysis of constrained damping treatments

One of the most effective ways of controlling vibrations in plate or beam structures is by means of constrained viscoelastic damping treatments. Contrary to the unconstrained configuration, the design of constrained and integrated layer damping treatments is multifaceted because the thickness of the viscoelastic layer acts distinctly on the two main counterparts of the strain energy the volume of viscoelastic material and the shear strain field. In this work, a parametric study is performed exploring the effect that the design parameters, namely the thickness/length ratio, constraining layer thickness, material modulus, natural mode and boundary conditions have on these two counterparts and subsequently, on the treatment efficiency. This paper presents five parametric studies, namely, the thickness/length ratio, the constraining layer thickness, material properties, natural mode and boundary conditions. The results obtained evidence an interesting effect when dealing with very thin viscoelastic layers that contradicts the standard treatment efficiency vs. layer thickness relation; hence, the potential optimisation of constrained and integrated viscoelastic treatments through the use of properly designed thin multilayer configurations is justified. This work presents a dimensionless analysis and provides useful general guidelines for the efficient design of constrained and integrated damping treatments based on single or multi-layer configurations. (C) 2012 Elsevier Ltd. All rights reserved.

Capacitive effects in pinpin photodiodes

The application of a-SiC:H/a-Si:H pinpin photodiodes for optoelectronic applications as a WDM demultiplexer device has been demonstrated useful in optical communications that use the WDM technique to encode multiple signals in the visible light range. This is required in short range optical communication applications, where for costs reasons the link is provided by Plastic Optical Fibers. Characterization of these devices has shown the presence of large photocapacitive effects. By superimposing background illumination to the pulsed channel the device behaves as a filter, producing signal attenuation, or as an amplifier, producing signal gain, depending on the channel/background wavelength combination. We present here results, obtained by numerical simulations, about the internal electric configuration of a-SiC:H/a-Si:H pinpin photodiode. These results address the explanation of the device functioning in the frequency domain to a wavelength tunable photo-capacitance due to the accumulation of space charge localized at the bottom diode that, according to the Shockley-Read-Hall model, it is mainly due to defect trapping. Experimental result about measurement of the photodiode capacitance under different conditions of illumination and applied bias will be also presented. The combination of these analyses permits the description of a wavelength controlled photo-capacitance that combined with the series and parallel resistance of the diodes may result in the explicit definition of cut off frequencies for frequency capacitive filters activated by the light background or an oscillatory resonance of photogenerated carriers between the two diodes. (C) 2013 Elsevier B.V. All rights reserved.

Implications of the Intervention Program for Physical Activity (IPPA) in the perception of illness and wellbeing in people with Multiple Sclerosis (MS)

The aim of this study is to examine the implications of the IPPA in the perception of illness and wellbeing in MS patients. Methods - This is a quasi experimental study non-randomized study with 24 MS patients diagnosed at least 1 year before, and with an EDSS score of under 7. We used the IPPA in 3 groups of eight people in 3 Portuguese hospitals (Lisbon, Coimbra, and Porto). The sessions were held once a week for 90 minutes, over a period of 7 weeks. The instruments used were: We asked the subjects the question “Please classify the severity of your disease?” and used the Personal Wellbeing Scale (PWS) at the beginning (time A) and end (time B) of the IPPA. We used the SPSS version 20. A non-parametric statistical hypothesis test (Wilcoxon test) was used for the variable analysis. The intervention followed the recommendations of the Helsinki Declaration. Results – The results suggest that there are differences between time A and B, the perception of illness decreased (p<0.08), while wellbeing increased (p<0.01). Conclusions: The IPPA can play an important role in modifying the perception of disease severity and personal wellbeing.

Avaliação de desempenho ambiental da Câmara Municipal da Ribeira Grande (São Miguel, Açores) : água e resíduos

Dissertação de Mestrado em Ambiente, Saúde e Segurança.

Cluster analysis using affinity aoefficient in order to identify religious beliefs profiles

International Scientific Forum, ISF 2013, ISF 2013, 12-14 December 2013, Tirana.

Bullying in hazing pratices : a study on higher education

7 th International Conference of Education, Research and Innovation (ICERI2014 Proceedings), Seville, Spain, 17-19 November 2014.

Classificação de atividades físicas através do uso do acelerómetro do smartphone

Dissertação de natureza científica realizada para a obtenção do grau de Mestre em Engenharia de redes de comunicação e Multimédia

Sistema de teste de transístores bipolares de junção e de efeito de campo

O estudo das curvas características de um transístor permite conhecer um conjunto de parâmetros essenciais à sua utilização tanto no domínio da amplificação de sinais como em circuitos de comutação. Deste estudo é possível obter dados em condições que muitas vezes não constam na documentação fornecida pelos fabricantes. O trabalho que aqui se apresenta consiste no desenvolvimento de um sistema que permite de forma simples, eficiente e económica obter as curvas características de um transístor (bipolar de junção, efeito de campo de junção e efeito de campo de metal-óxido semicondutor), podendo ainda ser utilizado como instrumento pedagógico na introdução ao estudo dos dispositivos semicondutores ou no projecto de amplificadores transistorizados. O sistema é constituído por uma unidade de condicionamento de sinal, uma unidade de processamento de dados (hardware) e por um programa informático que permite o processamento gráfico dos dados obtidos, isto é, traçar as curvas características do transístor. O seu princípio de funcionamento consiste na utilização de um conversor Digital-Analógico (DAC) como fonte de tensão variável, alimentando a base (TBJ) ou a porta (JFET e MOSFET) do dispositivo a testar. Um segundo conversor fornece a variação da tensão VCE ou VDS necessária à obtenção de cada uma das curvas. O controlo do processo é garantido por uma unidade de processamento local, baseada num microcontrolador da família 8051, responsável pela leitura dos valores em corrente e em tensão recorrendo a conversores Analógico-Digital (ADC). Depois de processados, os dados são transmitidos através de uma ligação USB para um computador no qual um programa procede à representação gráfica, das curvas características de saída e à determinação de outros parâmetros característicos do dispositivo semicondutor em teste. A utilização de componentes convencionais e a simplicidade construtiva do projecto tornam este sistema económico, de fácil utilização e flexível, pois permite com pequenas alterações

Immunohistochemistry in formalin-gel fixed tissues

There are several hazards in histopathology laboratories and its staff must ensure that their professional activity is set to the highest standards while complying with the best safety procedures. Formalin is one of the chemical hazards to which such professionals are routinely exposed. To decrease this contact, it is suggested that 10% neutral buffered liquid formalin (FL) is replaced by 10% formalin-gel (FG), given the later reduces the likelihood of spills and splashes, and decreased fume levels are released during its handling, proving itself less harmful. However, it is mandatory to assess the effectiveness of FG as a fixative and ensure that the subsequent complementary techniques, such as immunohistochemistry (IHC), are not compromised. Two groups of 30 samples from human placenta have been fixed with FG and FL fixatives during different periods of time (12, 24, and 48 hours) and, thereafter, processed, embedded, and sectioned. IHC for six different antibodies was performed and the results were scored (0–100) using an algorithm that took into account immunostaining intensity, percentage of staining structures, non-specific immunostaining, contrast, and morphological preservation. Parametric and non-parametric statistical tests were used (alpha = 0•05). All results were similar for both fixatives, with global score means of 95•36±6•65 for FL and 96•06±5•80 for FG, and without any statistical difference (P>0•05). The duration of the fixation had no statistical relevance also (P>0•05). So it is proved here FG could be an effective alternative to FL.

Entrepreneurship Education : The role of the Higher Education Institutions in the Entrepreneurial Attitudes of the Students

8th International Conference of Education, Research and Innovation. 18-20 November, 2015, Seville, Spain.

Difficulties in the Learning of Statistics by the Students of the Primary Education

The present study, covering students from public schools and a private school on the island of São Miguel (Azores, Portugal), aims to meet the difficulties of the students of the 3rd and 4th years of the primary education in solving tasks involving construction, reading and interpreting tables and statistical graphs, in the context of Organization and Data Handling (ODH). We present the main results obtained from statistical methods, among which we highlight some non-parametric hypothesis tests and the Categorical Principal Component Analysis (CatPCA), given the nature of the variables included in the questionnaire (mostly nominal and ordinal variables).

A new bridge between leptonic CP violation and leptogenesis

Flavour effects due to lepton interactions in the early Universe may have played an important role in the generation of the cosmological baryon asymmetry through leptogenesis. If the only source of high-energy CP violation comes from the left-handed leptonic sector, then it is possible to establish a bridge between flavoured leptogenesis and low-energy leptonic CP violation. We explore this connection taking into account our present knowledge about low-energy neutrino parameters and the matter-antimatter asymmetry observed in the Universe. In this framework, we find that leptogenesis favours a hierarchical light neutrino mass spectrum, while for quasi-degenerate and inverted hierarchical neutrino masses there is a very narrow allowed window. The absolute neutrino mass scale turns out to be m less than or similar to 0.1 eV. (c) 2007 Elsevier B.V. All rights reserved.

Three-dimensional modeling of tongue during speech using MRI data

The tongue is the most important and dynamic articulator for speech formation, because of its anatomic aspects (particularly, the large volume of this muscular organ comparatively to the surrounding organs of the vocal tract) and also due to the wide range of movements and flexibility that are involved. In speech communication research, a variety of techniques have been used for measuring the three-dimensional vocal tract shapes. More recently, magnetic resonance imaging (MRI) becomes common; mainly, because this technique allows the collection of a set of static and dynamic images that can represent the entire vocal tract along any orientation. Over the years, different anatomical organs of the vocal tract have been modelled; namely, 2D and 3D tongue models, using parametric or statistical modelling procedures. Our aims are to present and describe some 3D reconstructed models from MRI data, for one subject uttering sustained articulations of some typical Portuguese sounds. Thus, we present a 3D database of the tongue obtained by stack combinations with the subject articulating Portuguese vowels. This 3D knowledge of the speech organs could be very important; especially, for clinical purposes (for example, for the assessment of articulatory impairments followed by tongue surgery in speech rehabilitation), and also for a better understanding of acoustic theory in speech formation.

Efeitos da sobrecarga das mochilas escolares nas alterações posturais e de equilíbrio

Mestrado em Fisioterapia

Reproducibility of simulated myocardial lesions simulated on a virtual phantom

Human virtual phantoms are being widely used to simulate and characterize the behavior of different organs, either in diagnosis stages but also to enable foreseeing the therapeutic effects obtained on a certain patient. In the present work a typical patient’s heart was simulated using XCAT2©, considering the possibility of a lesion and/or anatomical alteration being affecting the myocardium. These simulated images, were then used to carry out a set of parametric studies using Matlab©. Although performed in controlled sceneries, these studies are very important to understand and characterize the performance of the methodologies used, as well as to determine to what extent the relations between the perturbation introduced at the myocardium and the resulting simulated images can be considered conclusive.