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論文
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長屋, 幸助 ; 湯澤, 秀人 ; 村上, 岩範
概要:
application/pdf<br />Journal Article<br />Since a commutator of the DC-motor is divided into a number of segments to have the torque in the circumference direction, the currents in the coils of the rotor vary and have alternative
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waves during the rotor rotation even in a constant input voltage. The currents become sharp waves, so that they have high frequency component. This implies that the rotor shaft and the case of motor are excited electromagnetic forces with high frequency components. Since high frequency noises are loud when they are input to human ears, so that when high frequency vibrations are suppressed, noises become small. From the situation, this paper discusses a method of noise reduction of Dc Motor. In the method, the current waves are controlled to be sinusoidal waves. The method and the control algorithm are given. In order to validate the method, experimental tests are carried out. It is proven that our method is applicable to the motor noise control.
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| 2.
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図書
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Maurice Petyt
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Alexander F. Vakakis ... [et al.]
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論文
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李, 連進 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />We present a system for reducing noise from structures using electromagnetic vibration absorbers. Conventional design techniques for vibration absorbers are not appropriate for noise reduction
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absorbers, because higher-mode vibrations exert strong effects on noise. Hence, we first derive an analytical expression for noise power including higher modes, then present a method for obtaining optimal parameters for noise reduction absorbers. In this method, noise power is taken as a function of cost, and the parameters are decided by using a neural network procedure. An improved algorithm of the neural network for obtaining the parameters is given, experimental tests are performed and the theoretical values are compared with the experimental data.
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| 5.
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論文
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李, 連進 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />This paper presents a method for optimizing vibration absorbers on a flexible beam by means of a neural network procedure. Analytical results for the response of the beam with multi-absorbers
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have been obtained using a transfer matrix method. To achieve optimal control, a cost function composed of second-order nonlinear forms in terms of the displacement, strain, and frequencies was used. A method of minimizing the function was presented, in which input values, weights and output function were effectively controlled on the basis of the back-propagation procedure of the neural network method. Numerical calculations were carried out for an example problem. It is ascertained that the present method gives a better result than that obtained by the previously published method. The validity of the method and the analytical results was confirmed by experimental tests.
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| 6.
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論文
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王, 建春 ; 横田, 正二 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />Bending vibrations of a pipe system are trasmitted to an evaporator and generate noise in an air conditioning system. Hence to reduce noise, bending vibrations should be reduced. This paper
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presents a method for reducing bending vibrations of a pipe system by use of curve tube elements. As a first step, to discuss the validity of the simulation program based on our previous analyses, experimental tests have been performed, and the simulation results are compared with the experimental data for some typical cases. Then, the bending vibrations are calculated for pipe systems with the proposed curved tube elements. It is clarified that the method presented plays an important role in reducing bending vibrations in the pipe system.
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| 7.
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論文
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長屋, 幸助
概要:
application/pdf<br />Journal Article<br />This paper discusses an actuator consisting of a permanent magnet with an electromagnet and a high Tc superconducting disc. An analytical solution for calculating levitation forces
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for the system was obtained. The obtained levitation force coincided with the previously published result. The equation of motion of the levitated body subjected to base disturbances under control was presented. Numerical calculations were carried out for some typical cases. Nonlinear vibrations of the system were first discussed, then the method of vibration isolation control using the direct disturbance cancellation combining the velocity feedback control was discussed. It was clarified that the present control method is valid for controlling the nonlinear system like the magnetically levitated superconducting body.
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| 8.
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論文
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長屋, 幸助 ; 鄭, 惟
概要:
application/pdf<br />Journal Article<br />This paper discusses vibration control problems of a cantilever plate with variable width. A moment-type actuator using a moving coil was presented. A mothod for obtaining optimal feedback
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coefficients was proposed on the basis of neural networks. An analytial solution for the response of the plate under the control using the feedback coefficients was obtained. Numerical calculations were carried out for some typical cases. It is clarified that the present method is valid for controlling vibrations of plates.
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| 9.
図書 |
図書
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Thomas D. Rossing, Neville H. Fletcher
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論文
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王, 建春 ; 長屋, 幸助 ; 横田, 正二
概要:
application/pdf<br />Journal Article<br />This paper presents a method for obtaining vibration response of a viscoelastic spiral rod having straight portions on viscoelastic supports. The expressions for calculating frequency
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response are obtained by means of the transfer matrix method, in which the exact solution of the differential equations with twelve state variables for the static deflection is applied. Inertia forces and rotatory inertia are included by making use of the point transfer matrix, and the bent portions are also considered by including the transfer matrix of coordinates. Numerical calculations were carried out for the rod with both an elastic portion and a viscoelastic portion carrying a mass at the end. In this problem, the rotary vibration is of importance because it generates noise, hence the location of the viscoelastic support which induces the rotary vibration of the mass minimum is discussed in detail. The fuzzy algorithm by which the optimal location of the supports is obtained is also presented.
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