Sirenko Feliks, Yepifanov Sergiy, Podgorsky Kostyantyn and Nechunaev Sergiy
The paper deals with the new approach to torque measurement in turboshafts. New construction of torque measurement is described with the highlighted advantages of the construction. The paper familiarizes the reader with the step-by-step algorithm of the torque measurement. As torque measurement units are not ideal, i.e. have manufacturing inaccuracies, so each unit has its own performance. The calibration algorithm to be in charge of obtaining the individual performance from the ideal one is described in the paper as well.
This work presents a torque measurement method of 3-degree-of-freedom (3-DOF) haptic master featuring controllable electrorheological (ER) fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.
Aleksandrs Gasparjans, Aleksandrs Terebkovs and Anastasia Zhiravetska
A method of technical diagnostics of ship diesel engine – generator installation – is proposed. Spectral-power diagnostic parameters of the synchronous generator voltage and currents are used. The electric machine in this case is the multipurpose sensor of diagnostic parameters. A judgment on the quality of the operational processes in diesel engine cylinders and its technical condition is possible on the basis of these parameters. This method is applicable to piston compressor installations with electric drive. On the basis of such parameters as rotating torque, angular speed and angular acceleration it is possible to estimate the quality of the operating process in the cylinders of a diesel engine, the condition of its cylinder-piston group and the crank gear mechanism. The investigation was realized on the basis of a diesel-generator with linear load. The generator operation was considered for the case of constant RL load. Together with the above mentioned, the condition of bearings of synchronous machines, uniformity of the air gap, windings of the electric machine were estimated during the experiments as well. The frequency spectrum of the stator current of the generator was researched and analyzed. In this case the synchronous machine is becoming a rather exact multipurpose diagnostic sensor. The signal of non-uniformity in the operation process of diesel engine cylinders and its technical condition is the increasing of the amplitudes of typical frequencies.
Krzysztof Buśko, Jan Gajewski, Joanna Mazur-Różycka, Radosław Michalski and Patrycja Łach
Study aim: The aim of the present study was to determine a strength profile which characterizes young male athletes from different sports and to use the method of allometry to synthetically evaluate the muscular strength with respect to body mass.
Material and methods: The study included 85 men who practiced taekwondo (8 subjects), 20 judoists, 10 weightlifters, 35 canoeists and 12 speed skaters. Measurements of maximal muscle torques in 10 groups of flexors and extensors of the elbow, shoulder, hip, knee and trunk were carried out in a testing station for muscle torque measurements under static conditions. In order to determine the relationships between the body mass and muscle torques in each muscle group, the authors used a procedure of linear regression for the data expressed as logarithms. Hence, the allometric relationship scaled with body mass was obtained.
Results: The study demonstrated that the mean values of logarithms of maximal muscle torques are significantly different for the representatives of individual sports and they depend on the logarithm of body mass. The analysis of residuals was employed for the evaluation of maximal muscle torques. The highest strength profiles were observed in athletes who practice judo and the lowest in those who represented weightlifting and taekwondo.
Conclusion: The authors propose to use an allometric relationship which takes body mass into consideration during evaluation of strength in individual muscle groups, because the values of muscle torques are not in direct proportion to body mass and their mutual proportions change with an increase in body mass.
Christian Froyd, Fernando G. Beltrami, Jørgen Jensen, Guillaume Y. Millet and Timothy David Noakes
The aim of this study was to investigate the effect of potentiation on stimulation-induced muscle function during and after an intense bout of self-paced dynamic exercise. Ten active subjects performed a time trial involving repetitive concentric extension-flexion of the right knee using a Biodex dynamometer. Electrical stimulation before and after a 5 s maximal isometric voluntary contraction was performed before the start of the time trial and immediately (< 5 s) after each 20% of the time trial as well as 1, 2, 4 and 8 min after time trial termination. Potentiation was observed before the time trial and as early as 1-2 min after the time trial, but no potentiation was detected during or immediately after the time trial for neither single or paired stimuli. At termination of the time trial, “potentiated” peak torque was significantly more reduced than “unpotentiated" peak torque for single stimulus (-65 ± 10% and -42 ± 18%, respectively) and paired stimuli at 100 Hz (-51 ± 10% and -33 ± 15%, respectively). Faster recovery for “potentiated” compared to “unpotentiated” peak torque indicate that potentiate peak torque measurements or delay the post-exercise measurements more than a few seconds, will underestimate peripheral fatigue. In conclusion, the potentiation after maximal contraction disappears during intense exercise. Whether the muscle is already potentiated during intense contraction or fatiguing mechanisms inhibits potentiation remains to be clarified
Alberto César Pereira de Carvalho Froufe Andrade, Paolo Caserotti, Carlos Manuel Pereira de Carvalho, Eduardo André de Azevedo Abade and António Jaime da Eira Sampaio
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