Fractional derivatives: probability interpretation and frequency response of rational approximations

The theory of fractional calculus (FC) is a useful mathematical tool in many applied sciences. Nevertheless, only in the last decades researchers were motivated for the adoption of the FC concepts. There are several reasons for this state of affairs, namely the co-existence of different definitions and interpretations, and the necessity of approximation methods for the real time calculation of fractional derivatives (FDs). In a first part, this paper introduces a probabilistic interpretation of the fractional derivative based on the Grünwald-Letnikov definition. In a second part, the calculation of fractional derivatives through Padé fraction approximations is analyzed. It is observed that the probabilistic interpretation and the frequency response of fraction approximations of FDs reveal a clear correlation between both concepts.

Compact, frequency reconfigurable, printed monopole antenna

This paper proposes a possible implementation of a compact printed monopole antenna, useful to operate in UMTS and WLAN bands. In order to accomplish that, a miniaturization technique based on the application of chip inductors is used in conjunction with frequency reconfiguration capability. The chip inductors change the impedance response of the monopole, allowing to reduce the resonant frequency. In order to be able to operate the antenna in these two different frequencies, an antenna reconfiguration technique based on PIN diodes is applied. This procedure allows the change of the active form of the antenna leading to a shift in the resonant frequency. The prototype measurements show good agreement with the simulation results.

Time-frequency and time-scale characterisation of the beat-by-beat high-resolution electrocardiogram

Proceedings of the Sixth Portuguese Conference on Bioemedical Engineering faro, Portugal

Radio frequency identification: o futuro da gestão de stocks na grande distribuição

Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação

How to Measure the Deterrence Effects of Merger Policy: Frequency or Composition?

We show that the number of merger proposals (frequency-based deterrence) is a more appropriate indicator of underlying changes in merger policy than the relative anti-competitiveness of merger proposals (composition-based deterrence). This has strong implications for the empirical analysis of the deterrence effects of merger policy enforcement, and potential implications regarding how to reduce anti-competitive merger proposals.

Os trabalhos para casa no 1.º ciclo do ensino básico – conceções de alunos e professor

Relatório Final apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º e do 2.º Ciclo do Ensino Básico

Comparative analysis of time-frequency methods estimating the time-varying microstructure of sleep EEG spindles

Proceedings of the Information Technology Applications in Biomedicine, Ioannina - Epirus, Greece, October 26-28, 2006

On performance of distributed model predictive control in power system frequency regulation

This paper describes the implementation of a distributed model predictive approach for automatic generation control. Performance results are discussed by comparing classical techniques (based on integral control) with model predictive control solutions (centralized and distributed) for different operational scenarios with two interconnected networks. These scenarios include variable load levels (ranging from a small to a large unbalance generated power to power consumption ratio) and simultaneously variable distance between the interconnected networks systems. For the two networks the paper also examines the impact of load variation in an island context (a network isolated from each other).

Low frequency of TERT promoter mutations in gastrointestinal stromal tumors (GISTs)

Somatic mutations in the promoter region of telomerase reverse transcriptase (TERT) gene, mainly at positions c.-124 and c.-146 bp, are frequent in several human cancers; yet its presence in gastrointestinal stromal tumor (GIST) has not been reported to date. Herein, we searched for the presence and clinicopathological association of TERT promoter mutations in genomic DNA from 130 bona fide GISTs. We found TERT promoter mutations in 3.8% (5/130) of GISTs. The c.-124C>T mutation was the most common event, present in 2.3% (3/130), and the c.-146C>T mutation in 1.5% (2/130) of GISTs. No significant association was observed between TERT promoter mutation and patient's clinicopathological features. The present study establishes the low frequency (4%) of TERT promoter mutations in GISTs. Further studies are required to confirm our findings and to elucidate the hypothetical biological and clinical impact of TERT promoter mutation in GIST pathogenesis.

The frequency of blood-born viral infections in a population of multitransfused Brazilian patients

The frequency of viral markers for hepatitis B (HBV) and C (HCV), human immunodeficiency virus-1 (HIV-1) and human T-lymphotropic virus-1 (HTLV-1) was evaluated in 32 Brazilian ß-thalassemia multitransfused patients. Additionaly the serum concentrations of ferritin and alanine aspartate transaminase (ALAT) were determined. The results show a high prevalence of markers of infection by HBV (25.0%) and HCV (46.8%) and a low prevalence of markers for HIV-1 and HTLV-1. No correlations were demonstrated between the presence of the hepatitis markers and the number of units transfused or the serum concentrations of ferritin and ALAT.

Complementary filter design with three frequency bands: robot attitude estimation

This paper extents the by now classic sensor fusion complementary filter (CF) design, involving two sensors, to the case where three sensors that provide measurements in different bands are available. This paper shows that the use of classical CF techniques to tackle a generic three sensors fusion problem, based solely on their frequency domain characteristics, leads to a minimal realization, stable, sub-optimal solution, denoted as Complementary Filters3 (CF3). Then, a new approach for the estimation problem at hand is used, based on optimal linear Kalman filtering techniques. Moreover, the solution is shown to preserve the complementary property, i.e. the sum of the three transfer functions of the respective sensors add up to one, both in continuous and discrete time domains. This new class of filters are denoted as Complementary Kalman Filters3 (CKF3). The attitude estimation of a mobile robot is addressed, based on data from a rate gyroscope, a digital compass, and odometry. The experimental results obtained are reported.

Establishment of optimal physical assets inspection frequency based on risk principles

Risk Based Inspection (RBI) is a risk methodology used as the basis for prioritizing and managing the efforts for an inspection program allowing the allocation of resources to provide a higher level of coverage on physical assets with higher risk. The main goal of RBI is to increase equipment availability while improving or maintaining the accepted level of risk. This paper presents the concept of risk, risk analysis and RBI methodology and shows an approach to determine the optimal inspection frequency for physical assets based on the potential risk and mainly on the quantification of the probability of failure. It makes use of some assumptions in a structured decision making process. The proposed methodology allows an optimization of inspection intervals deciding when the first inspection must be performed as well as the subsequent intervals of inspection. A demonstrative example is also presented to illustrate the application of the proposed methodology.

Estimation of rotational frequency response functions

As it is widely known, in structural dynamic applications, ranging from structural coupling to model updating, the incompatibility between measured and simulated data is inevitable, due to the problem of coordinate incompleteness. Usually, the experimental data from conventional vibration testing is collected at a few translational degrees of freedom (DOF) due to applied forces, using hammer or shaker exciters, over a limited frequency range. Hence, one can only measure a portion of the receptance matrix, few columns, related to the forced DOFs, and rows, related to the measured DOFs. In contrast, by finite element modeling, one can obtain a full data set, both in terms of DOFs and identified modes. Over the years, several model reduction techniques have been proposed, as well as data expansion ones. However, the latter are significantly fewer and the demand for efficient techniques is still an issue. In this work, one proposes a technique for expanding measured frequency response functions (FRF) over the entire set of DOFs. This technique is based upon a modified Kidder's method and the principle of reciprocity, and it avoids the need for modal identification, as it uses the measured FRFs directly. In order to illustrate the performance of the proposed technique, a set of simulated experimental translational FRFs is taken as reference to estimate rotational FRFs, including those that are due to applied moments.

Utilização de PAM's e Medicamentos e/ou Produtos à base de Plantas pela População do Concelho de Bragança

Introdução: Entende-se por fitoterapia a terapêutica caracterizada pelo uso de plantas medicinais nas diferentes formas farmacêuticas com finalidade terapêutica, usada assim para prevenir, atenuar ou curar um estado patológico. Objetivos: Caracterizar a utilização de plantas aromáticas e medicinais (PAM´s), medicamentos e produtos à base de plantas pela população do concelho de Bragança, conhecer a fonte de indicação deste tipo de produtos, apurar a relação entre a fonte de indicação e o estado de saúde após a utilização, verificar a sua correta utilização relativa à indicação terapêutica, modo e frequência de utilização, identificar potenciais interacções medicamentosas, averiguar se os utentes informam o médico do seu uso, investigar a ocorrência de efeitos adversos e apurar a relação entre os efeitos adversos ocorridos e o género dos inquiridos. Métodos: Trata-se de um estudo observacional analítico-transversal. Nele participaram 404 indivíduos de ambos os géneros e com idades compreendidas entre os 18 e os 89 anos. A recolha de dados foi realizada entre os meses de abril e junho de 2014, através de um questionário estruturado de autopreenchimento, formado por 30 perguntas. Após a recolha dos dados procedeu-se à leitura óptica dos questionários, sendo os dados posteriormente exportados para SPSS permitindo assim o tratamento dos mesmos. Para análise estatística utilizou-se o teste do qui-quadrado considerando o nível de significância p <0,05. Resultados: Verificou-se que 53,7% dos inquiridos recorre terapeuticamente a PAM´s que inclui principalmente o uso de cidreira e camomila enquanto 33,8% faz uso de medicamentos e/ou produtos àbase de plantas nomeadamente Valdispert e Daflon. A utilização de PAM,s é motivada por autoconhecimento e indicação de familiares, amigos e vizinhos. Já os medicamentos e/ou produtos à base de plantas são utilizados maioritariamente por prescrição médica e indicação na farmácia. A ocorrência de efeitos indesejáveis foi sentida unicamente com a utilização de PAM´s e em pequena escala. Conclusão: O recurso a este tipo de produtos é uma prática bastante comum entre os moradores do concelho de Bragança, que utilizam uma grande diversidade de plantas e produtos à base de plantas para um variado leque de indicações terapêuticas, apontando a percentagem de respostas para um conhecimento dos seus efeitos terapêuticos.