Desenvolvimento e implementação de estratégias de controle digital para regulação de tensão e amortecimento de oscilações eletromecânicas em um gerador síncrono de 10kVA

Neste trabalho são apresentados o desenvolvimento e a implementação de estratégias de controle digital para regulação automática de tensão e para o amortecimento de oscilações eletromecânicas em um sistema de potência em escala reduzida de 10kVA, localizado no Laboratório de Controle de Sistemas de Potência (LACSPOT), da Universidade Federal do Pará (UFPA). O projeto dos dois controladores é baseado na técnica de alocação polinomial de polos. Para o projeto do Regulador Automático de Tensão (RAT) foi adotado um modelo simplificado, de primeira ordem, da máquina síncrona, cujos parâmetros foram levantados experimentalmente. Para o controlador amortecedor, por sua vez, também chamado de Estabilizador de Sistemas de Potência (ESP), foi utilizado um modelo discreto, do tipo auto regressivo com entrada exógena (ARX). Este modelo foi estimado por meio de técnicas de identificação paramétrica, considerando para tal, o conjunto motor-gerador interligado a um sistema de maior porte (concessionária de energia elétrica). As leis de controle foram embarcadas em um microcontrolador de alto desempenho e, para a medição dos sinais utilizados nos controladores, foi desenvolvida uma instrumentação eletrônica baseada em amplificadores operacionais para o condicionamento dos sinais dos sensores. O sinal de controle é baseado na técnica de modulação por largura de pulso (PWM) e comanda o valor médio da tensão de um conversor CC-CC, o qual é utilizado como circuito de excitação que energiza o enrolamento de campo do gerador. Além disso, o acionamento elétrico das máquinas que compõem o grupo gerador de 10kVA foi projetado e automatizado somando segurança aos operadores e ao componentes deste sistema de geração. Os resultados experimentais demonstraram o bom desempenho obtido pela estratégia proposta.

Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation

This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m2 mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.

Wavelength assignment using a hybrid evolutionary computation to reduce cross-phase modulation

In this paper, we propose a hybrid methodology based on Graph-Coloring and Genetic Algorithm (GA) to solve the Wavelength Assignment (WA) problem in optical networks, impaired by physical layer effects. Our proposal was developed for a static scenario where the physical topology and traffic matrix are known a priori. First, we used fixed shortest-path routing to attend demand requests over the physical topology and the graph-coloring algorithm to minimize the number of necessary wavelengths. Then, we applied the genetic algorithm to solve WA. The GA finds the wavelength activation order on the wavelengths grid with the aim of reducing the Cross-Phase Modulation (XPM) effect; the variance due to the XPM was used as a function of fitness to evaluate the feasibility of the selected WA solution. Its performance is compared with the First-Fit algorithm in two different scenarios, and has shown a reduction in blocking probability up to 37.14% when considered both XPM and residual dispersion effects and up to 71.42% when only considered XPM effect. Moreover, it was possible to reduce by 57.14% the number of wavelengths.

The influence of resistance exercise with emphasis on specific contractions (concentric vs. eccentric) on muscle strength and post-exercise autonomic modulation: a randomized clinical trial

Contextualização:Ações concêntricas apresentam maior estresse cardiovascular quando comparadas às excêntricas. Entretanto, não se sabe a influência desses tipos de ações no comportamento da modulação autonômica cardíaca durante o processo de recuperação pós-esforço.Objetivo:Comparar o efeito de um treinamento resistido para o grupo extensor do joelho realizado com ênfase concêntrica vs excêntrica sobre a força muscular e a recuperação pós-exercício considerando índices de variabilidade de frequência cardíaca (VFC) em jovens saudáveis.Método:Cento e cinco homens, com idades entre 18 e 30 anos, foram randomizados em quatro grupos: controle concêntrico (CCONC), controle excêntrico (CEXC), treinamento concêntrico (TCONC) e treinamento excêntrico (TEXC). Os grupos CCONC e CEXC realizaram uma sessão de exercício reduzido (ER) para o grupo extensor do joelho [três séries de uma repetição a 100% de uma repetição máxima (1RM)], e os grupos TCONC e TEXC realizaram dez sessões de treinamento. A VFC foi analisada no momento basal e na recuperação após as sessões (T1, T2, T3 e T4).Resultados:Observou-se aumento da força muscular para o grupo TEXC. Em relação à modulação autonômica cardíaca, observou-se, em comparação ao momento basal, aumento dos índices SDNN e SD2 no momento T1 nos grupos CCONC e CEXC e aumento dos índices RMSSD, SD1 e AF (ms2) nos momentos T1, T2 e T4 no grupo TEXC.Conclusões:Conclui-se que o treinamento resistido realizado com ênfase em contrações excêntricas promoveu ganho de força e aumento da modulação vagal cardíaca durante o processo de recuperação em relação à condição basal.

Effects of rotation in the laser-pulse photoassociation in a thermal gas of atoms

Photoassociation is a possible route for the formation of chemical bonds. In this process, the binding of colliding atoms can be induced by means of a laser field. Photoassociation has been studied in the ultracold regime and also with temperatures well above millikelvins in the thermal energy domain, which is a situation commonly encountered in the laboratory. A photoassociation mechanism can be envisioned based on the use of infrared pulses to drive a transition from free colliding atoms on the electronic ground state to form a molecule directly on that state. This work takes a step in this direction, investigating the laser-pulse-driven formation of heteronuclear diatomic molecules in a thermal gas of atoms including rotational effects. Based on the assumption of full system controllability, the maximum possible photoassociation yield is deduced. The photoassociation probability is calculated as a function of the laser parameters for different temperatures. Additionally, the photoassociation yield induced by subpicosecond pulses of a priori fixed shape is compared to the maximum possible yield.

Resveratrol improves bone repair by modulation of bone morphogenetic proteins and osteopontin gene expression in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Serotonergic modulation in neuropathy induced by oxaliplatin: Effect on the 5HT(2C) receptor

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modulation of cell proliferation, survival and gene expression by RAGE and TLR signaling in cells of the innate and adaptive immune response: role of p38 MAPK and NF-KB

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Differential modulation of sympathetic and respiratory activities by cholinergic mechanisms in the nucleus of the solitary tract in rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of Pursed-Lip Breathing in Patients With COPD: Linear and Nonlinear Analysis of Cardiac Autonomic Modulation

Objective: The aim of the present study was to evaluate the effect of pursed-lip breathing (PLB) on cardiac autonomic modulation in individuals with chronic obstructive pulmonary disease (COPD) while at rest. Methods: Thirty-two individuals were allocated to one of two groups: COPD (n = 17; 67.29 +/- 6.87 years of age) and control (n = 15; 63.2 +/- 7.96 years of age). The groups were submitted to a two-stage experimental protocol. The first stage consisted of the characterization of the sample and spirometry. The second stage comprised the analysis of cardiac autonomic modulation through the recording of R-R intervals. This analysis was performed using both nonlinear and linear heart rate variability (HRV). In the statistical analysis, the level of significance was set to 5% (p = 0.05). Results: PLB promoted significant increases in the SD1, SD2, RMSSD and LF (ms(2)) indices as well as an increase in alpha(1) and a reduction in alpha(2) in the COPD group. A greater dispersion of points on the Poincare plots was also observed. The magnitude of the changes produced by PLB differed between groups. Conclusion: PLB led to a loss of fractal correlation properties of heart rate in the direction of linearity in patients with COPD as well as an increase in vagal activity and impact on the spectral analysis. The difference in the magnitude of the changes produced by PLB between groups may be related to the presence of the disease and alterations in the respiration rate.

Analysis of cardiac autonomic modulation of children with attention deficit hyperactivity disorder

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Autonomic modulation and its relation with body composition in swimmers

This study compared autonomic modulation in swimmers and non-athletes in relation to body composition. A total of 28 athletes with a mean age of 19.7 +/- 2.9 years were evaluated who had at least 2 years of swimming training, trained approximately 7,000 m per day, with a frequency of 5 days per week, and who competed at national level. The control group was made up of 21 volunteers (23.0 +/- 2.5 years), who did not practice regular physical activity (<2 hours per week). Body composition was estimated using dual-energy x-ray absorptiometry, and autonomic modulation was assessed by heart rate variability (HRV). The results show that there were significant differences in autonomic modulation and body composition between the groups, and that the athletes had a higher overall variability (standard deviation of all normal intervals between consecutive heart beats [SDNN]: 78.1 [72.5-93.5] x 61.1 [56.4-75.7], p = 0.022) and greater autonomic balance (LF/HF: 0.96 [0.88-1.35] x 0.71 [0.56-0.93], p = 0.023), compared with the non-athletes, respectively. In addition, a moderate and positive relation was obtained between fat-free mass and the square root of the squared differences between consecutive heartbeat intervals (RMSSD: r = 0.526, p = 0.004 x r = 0.456, p = 0.038), (SDNN: r = 0.617, p = 0.001 x r = 0.571, p = 0.007) and low frequency (LFms(2): r = 0.517, p = 0.005 3 r = 0.600, p = 0.004) in the athletes and non-athletes, respectively, without a correlation between fat mass (FM). The conclusion is that young highly trained swimmers had lower FM, increased fat-free mass, and better HRV than young adult non-athletes and suggests that a lower quantity of FM and, especially, a greater fat-free mass (FFM) are linked to better autonomic modulation. Thus, this study could contribute to coaches and trainers establishing greater performance by better autonomic modulation and greater quantity of FFM.

Modulation of HJURP (Holliday Junction-Recognizing Protein) Levels Is Correlated with Glioblastoma Cells Survival

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Solubility and release modulation effect of sulfamerazine ternary complexes with cyclodextrins and meglumine

This study investigated the effect on solubility and release of ternary complexes of sulfamerazine (SMR) with beta-(beta CD), methyl-(M beta CD) and hydroxypropyl-P-cyclodextrin (HP beta CD) using meglumine (MEG) as the ternary component. The combination of MEG with M beta CD resulted the best approach, with an increased effect (29-fold) of the aqueous solubility of SMR. The mode of inclusion was supported by 2D NMR, which indicated that real ternary complexes were formed between SMR, MEG and M beta CD or HP beta CD. Solid state analysis was performed using Fourier-transform infrared spectroscopy (FT IR), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD), which demonstrated that different interactions occurred among SMR, MEG and M beta CD or HP beta CD in the ternary lyophilized systems. The ternary complexes with beta CD and M beta CD produced an additional retention effect on the release of SMR compared to the corresponding binary complexes, implying that they were clearly superior in terms of solubility and release modulation. (C) 2014 Elsevier B.V. All rights reserved.