Controle de força e torque isométrico em crianças com e sem desordem coordenativa desenvolvimental

Esta tese teve como objetivos investigar: (1) as mudanças relacionadas à idade no controle de força e torque isométrico em crianças de diferentes idades em três tarefas manipulativas distintas, e (2) as diferenças no controle de força e torque isométrico, assim como nas respostas neuromusculares, entre crianças com e sem DCD de idade relacionadas em três tarefas manipulativas distintas. Neste sentido, foi realizado um ensaio teórico sobre a criança com Desordem Coordenativa Desenvolvimental (DCD), além de dois estudos experimentais que têm em comum a análise da estrutura da resposta do sistema motor em relação à performance das crianças com e sem DCD, em três tarefas manipulativas distintas de controle de força e torque isométrico, contínuo e constante. No primeiro estudo, foram investigadas as mudanças desenvolvimentais no controle motor usando um delineamento transversal de pesquisa com crianças de 7, 9 e 11 anos de idade, as quais foram incentivadas a manter o controle de força e torque durante vinte segundos nas tarefas de pressão digital, preensão digital em pinça e torque em preensão digital. Os resultados demonstraram que a performance melhorou com o avanço da idade, devido à capacidade do sistema sensório-motor apresentar uma resposta mais irregular e com um perfil de freqüências mais distribuídas. No segundo estudo, o controle de força e torque entre crianças com e sem DCD, com nove anos de idade, foram investigadas. Os participantes realizaram as mesmas tarefas do estudo desenvolvimental e, além disso, respostas neuromusculares foram mapeadas Os resultados não revelaram uma variabilidade maior e irregularidade menor no grupo com DCD nas tarefas de pressão digital e preensão digital em pinça. No entanto, na tarefa de controle de torque em preensão digital, foi identificada uma maior variabilidade e menor irregularidade na resposta motora do grupo com DCD. Os resultados não revelaram uma variabilidade maior e irregularidade menor no grupo com DCD nas tarefas de pressão digital e preensão digital em pinça. No entanto, na tarefa de controle de torque em preensão digital, foi identificada uma maior variabilidade e menor irregularidade na resposta motora do grupo com DCD. Os resultados da análise das respostas neuromusculares sugerem o uso de estratégias distintas entre os grupos, todavia, tais achados não foram conclusivos.

Desenvolvimento e avaliação de padrão de torque para calibração de torquímetros em três faixas de medição

The continuous development of instruments and equipment used as tools or torque measurement in the industry is demanding more accurate techniques in the use of this kind instrumentation, including development of metrological characteristics in torque measurement. The same happens with the needs in calibration services. There is a diversity of methods of hand torque tools in the market with different measuring range but without complaining with technical standards in terms of requirements of quality and reliability. However, actually there is no choice of a torque measuring standard that fulfils, with low cost, the needs for the calibration of hand torque tools in a large number of ranges. The objective of this thesis is to show the development and evaluation of a torque measuring standard device with a conception to allow the calibration of hand torque tools with three levels of torque with an single instrument, promoting reduction of costs and time in the calibration, also offering reliability for the evaluation of torque measuring instrument. To attend the demand in the calibration of hand torque tools it is necessary that the calibration laboratories have a big collection of torque measuring standards, to fulfills the needs of the costumer, what is very costly. The development of this type of torque measuring standard revealed a viable technique and economically making possible the calibration of hand torque tools in different nominal ranges through a single measurement system versatile, efficient and of easy operation

Correlação entre torque, equlíbrio e função do joelho após reconstrução do LCA

Background: Several studies emphasize the importance of assessing the knee function after anterior cruciate ligament (ACL) reconstruction. The influence of several variables on the function of these patients has been analyzed, but there is no consensus in the science literature. Purpose: To evaluate the correlation between the torque and balance on the knee function after ACL reconstruction. Methods: 23 males patients with ACL reconstruction were tested. The procedures of the study included analysis of concentric peak torque at 60o/s and 180o/s of quadriceps femoris and hamstring muscle with a isokinetic dynamometer. The balance in single-limb stance was measured with stabilometry. The functional performance were performed by two hop tests. To estimate the subjective function of the patients was applied Lysholm Knee Scoring Scale and a Global Rating scale. Results: The analysis of data showed a moderate positive correlation between knee extensor torque and functional performance tests (r= 0,48; p=0,02). A moderate negative correlation was found between the two variables of the stabilometry center of pressure and average speed of centre of pressure and the Global Rating scale (r = -0.4, p = 0,04 and r = -0,49, p = 0 ,02, respectively). No correlation was found between peak torque and balance in single-limb stance. Conclusion: The results of the present study suggest that knee extensor strength and postural balance have some influence on knee function in patients after ACL reconstruction

Efeito de três tecnicas de alongamento muscular sobre o torque e atividade eletromiográfica

PURPOSE: To examine the acute effects caused by three techniques for stretching the hamstrings muscle on the active concentric peak torque (PT), passive PT and electromyographic activity (EMG). METHODS: Sixty volunteers (mean ± SD age, 22.6 ± 3 years), height 1.64 ± 0.07m and body weight of 58 ± 8.6kg, were randomly allocated into 4 groups of 15 subjects: Control Group (CG) - 5 minutes at rest, Static Stretching Group (SG) - 2 x 30s; Hold-Relax Group (HRG) - 3 x 6s of isometric contraction of hamstrings interspersed by 10s of hamstrings stretching and agonist Hold-Relax Group (AHRG) - 3 x 6s of isometric contraction of the quadriceps interspersed by 10s of hamstrings stretching. Evaluation has been conducted preand post-intervention, which verified the active concentric PT, passive PT EMG activity of IT. The statistical inference was performed by testing intra and inter, significance level at 5%. RESULTS: After intervention, there was a reduction in passive PT on CG, accompanied by a reduction of EMG activity, and an increase in passive PT on SG and AHRG. There was no change in the active concentric PT, or change in EMG activity. CG showed an increase in angle of the PT active, while the other groups showed no change. CONCLUSION: The results suggest that the shortterm stretching: 1) causes acute increase in passive torque, since the muscle does not perform sub-maximal contraction, 2) does not change in electromyographic activity and active torque, ind ependent of the technique

Neural network based estimation of torque in induction motors for real-time applications

Induction motors are largely used in several industry sectors. The selection of an induction motor has still been inaccurate because in most of the cases the load behavior in its shaft is completely unknown. The proposal of this article is to use artificial neural networks for torque estimation with the purpose of best selecting the induction motors rather than conventional methods, which use classical identification techniques and mechanical load modeling. Since proposed approach estimates the torque behavior from the transient to the steady state, one of its main contributions is the potential to also be implemented in control schemes for real-time applications. Simulation results are also presented to validate the proposed approach.

Glucose consume and growth of E. coli under electromagnetic field

E. coli,em caldo glicosado,foi submetida a campo eletromagnético de intensidade 5G, gerado por fonte de tensão alternada de 60 Hz . Os crescimento e consumo de glicose foram avaliados através do teste não-paramétrico de Mann-Whitney para comparação de dois grupos. Após 8 h de exposição encontraram-se menor valor da glicose residual e maior turbidez nos tubos expostos ao campo evidenciando efeito positivo deste. A causa deste efeito no consumo da glicose pode ser pela estimulação de sistema de transporte de glicose, como a Difusão Facilitada ou por um tipo de fenômeno chamado ressonância ciclotrônica. O aumento do crescimento pode ser pelo encurtamento da lag phase e estimulação da log phase.

Spacecraft's attitude prediction: solar radiation torque and the Earth's shadow

A semi-analytical approach is proposed to study the rotational motion of an artificial satellite, under the influence of torque due to the solar radiation pressure, and taking into account the influence of Earth's shadow. Using Andoyer variables the equations for the rotational motion are presented in extended Hamiltonian form. In order to get a solution for the state variables close to an actual motion, the considered model for the shadow function takes into account physical and geometric factors and three specific regions: shadow, penumbra and full light. A mapping for the shadow function is proposed and a semi-analytical process is applied. When the satellite is totally illuminated or it is inside the penumbra, a known analytical solution is used to compute the satellite's attitude. A numerical simulation shows, when the penumbra region is included, the attenuation of the rotational motion during the transition from the shadow to the illuminate region and vice versa. (c) 2005 Published by Elsevier Ltd on behalf of COSPAR.

Analytical attitude prediction of spin stabilized spacecrafts perturbed by magnetic residual torque

An analytical approach for spin-stabilized spacecraft attitude prediction is presented for the influence of the residual magnetic torques. Assuming an inclined dipole model for the Earth's magnetic field, an analytical averaging method is applied to obtain the mean residual torque every orbital period. The orbit mean anomaly is utilized to compute the average components of residual torque in the spacecraft body frame reference system. The theory is developed for time variations in the orbital elements, and non-circular orbits, giving rise to many curvature integrals. It is observed that the residual magnetic torque does not have component along the spin axis. The inclusion of this torque on the rotational motion differential equations of a spin stabilized spacecraft yields conditions to derive an analytical solution. The solution shows that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spin axis of the spacecraft. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

Attitude stability of artificial satellites subject to gravity gradient torque

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Single-phase high power-factor boost ZCS pre-regulator operating in critical conduction mode

This paper presents a new single-phase interleaved high power factor boost pre-regulator operating in critical conduction mode, where the switches and boost diode performing zero-current commutations during its turn-off, eliminating the disadvantages related to the reverse recovery losses and electromagnetic interference problems of the boost diode, when operating in the continuous conduction mode. The interleaving technique is applied in the power cell, providing a significant input current ripple reduction in comparison to discontinuous mode of operation, due to its input current continuous conduction operation. This paper presents a complete modeling for the converter operating in critical conduction mode, resulting in an improved design procedure for interleaved techniques with high input power factor, a complete design procedure, and main simulation results from a design example with two interleaved cells rated at 1kW, 400V output voltage and 220V rms input voltage.

A 2kW interleaved ZCS-FM boost rectifier digitally controlled by FPGA device

This paper presents a 2kW single-phase high power factor boost rectifier with four cells in interleave connection, operating in critical conduction mode, and employing a soft-switching technique, controlled by Field Programmable Gate Array (FPGA). The soft-switching technique Is based on zero-current-switching (ZCS) cells, providing ZC (zero-current) turn-on and ZCZV (zero-current-zero-voltage) turn-off for the active switches, and ZV (zero-voltage) turn-on and ZC (zero-current) turn-off for the boost diodes. The disadvantages related 'to reverse recovery effects of boost diodes operated in continuous conduction mode (additional losses, and electromagnetic interference (EMI) problems) are minimized, due to the operation in critical conduction mode. In addition, due to the Interleaving technique, the rectifer's features include the reduction in the input current ripple, the reduction in the output voltage ripple, the use of low stress devices, low volume for the EMI input filter, high input power factor (PF), and low total harmonic distortion (THD) In the input current, in compliance with the TEC61000-3-2 standards. The digital controller has been developed using a hardware description language (VHDL) and implemented using a XC2S200E-SpartanII-E/Xilinx FPGA device, performing a true critical conduction operation mode for four interleaved cells, and a closed-loop to provide the output voltage regulation, like as a pre-regulator rectifier. Experimental results are presented for a 2kW implemented prototype with four interleaved cells, 400V nominal output voltage and 220V(rms) nominal input voltage, in order to verify the feasibility and performance of the proposed digital control through the use of a FPGA device.

Efficient procedure to evaluate electromagnetic transients on three-phase transmission lines

This paper presents a hybrid way mixing time and frequency domain for transmission lines modelling. The proposed methodology handles steady fundamental signal mixed with fast and slow transients, including impulsive and oscillatory behaviour. A transmission line model is developed based on lumped elements representation and state-space techniques. The proposed methodology represents an easy and practical procedure to model a three-phase transmission line directly in time domain, without the explicit use of inverse transforms. The proposed methodology takes into account the frequency-dependent parameters of the line, considering the soil and skin effects. In order to include this effect in the state matrices, a fitting method is applied. Furthermore the accuracy of proposed the developed model is verified, in frequency domain, by a simple methodology based on line distributed parameters and transfer function related to the input/output signals of the lumped parameters representation. In addition, this article proposes the use of a fast and robust analytic integration procedure to solve the state equations, enabling transient and steady-state simulations. The results are compared with those obtained by the commercial software Microtran (EMTP), taking into account a three-phase transmission line, typical in the Brazilian transmission system.

Torque, myoeletric sygnal and heart rate responses during concentric and eccentric exercises in older men

Background: The literature reports that the eccentric muscular action produces greater force and lower myoelectric activity than the concentric muscular action, while the heart rate (HR) responses are bigger during concentric contraction. Objectives: To investigate the maximum average torque (MAT), surface electromyographic (SEMG) and the heart rate (HR) responses during different types of muscular contraction and angular velocities in older men. Methods: Twelve healthy men (61.7 +/- 1.6years) performed concentric (C) and eccentric (E) isokinetic knee extension-flexion at 60 degrees/s and 120 degrees/s. SEMG activity was recorded from vastus lateralis muscle and normalized by Root Mean Square-RMS (mu V) of maximal isometric knee extension at 60 degrees. HR (beats/min) and was recorded at rest and throughout each contraction. The data were analyzed by the Friedman test for repeated measures with post hoc Dunn's test (p<0.05). Results: The median values of MAT (N.m/kg) was smaller and the RMS (mu V) was larger during concentric contraction (C60 degrees/s=2.80 and 0.99; C120 degrees/s=2.46 and 1.0) than eccentric (E60 degrees/s=3.94 and 0.85; E120 degrees/s=4.08 and 0.89), respectively. The HR variation was similar in the four conditions studied. Conclusion: The magnitude of MAT and RMS responses in older men were dependent of the nature of the muscular action and independent of the angular velocity, whereas HR response was not influenced by these factors.

Evaluation of Torque Maintenance of Abutment and Cylinder Screws With Morse Taper Implants

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

Effect of Severe Dietary Magnesium Deficiency on Systemic Bone Density and Removal Torque of Osseointegrated Implants

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