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| 1.
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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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長屋, 幸助 ; 小林, 譲二 ; 今井, 勝仁
概要:
application/pdf<br />Journal Article<br />This paper presents a method of micro-vibration control of milling machine heads by use of vibration absorber. The principle used in the paper is different from usual absorbers. In the
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present absorber, an auto-tuning vibration absorber is presented in which the absorber create anti-resonance state. When the anti-resonance is used, the damping has to be significantly small, so it is difficult to suppress higher modes. To suppress higher modes, the present article uses autotuning magnetic damper. It damps higher modes, but it also increase first modal vibration. Then a method of optimal auto tuning control is presented in which both principal and higher modal vibrations are suppressed. Experimental tests are carried out for a real milling machine, and cutting tests are also performed.
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| 3.
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長屋, 幸助 ; 小杉, 泰裕 ; 鈴木, 孝明 ; 村上, 岩範
概要:
application/pdf<br />Journal Article<br />A simple but stable non-contact high Tc superconducting levitation system with a vertical shaft has been presented. The system consists of a superconductor and permanent magnets. In the system,
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only a lower end of the shaft is supported by a high Tc superconductor, and the other end is supported by two ordinary permanent magnets. Since the restoring force is small with respect to the radial direction the system becomes unstable when the force act in the radial direction, so it is difficult to drive the shaft by electromagnetic forces in using such as motors. Then, a driving system using electromagnets has been presented, in which the balanced forces act on two opposite sides of the disc type rotor in the axial direction. Since the system has no unbalance force from an analytical point of view, the rotor will be able to rotate without control. In the system, however, since there is the eccentricity between the center of rotation and magnetic center, so vibrations are generated. This study also presents an optimal control method of the vibrations. To validates the proposed system, and the control method, experimental tests have been carried out.
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| 4.
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長屋, 幸助 ; 塚越, 正人 ; 小杉, 泰裕 ; 村上, 雅人
概要:
application/pdf<br />Journal Article<br />The present article discusses a modeling and control of high-T_c superconducting levitation system. The paper first clarifies analytical expressions for obtaining nonlinear levitation force
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given by the present author, then presents at vibration control method in which feedback currents involving frequency weights. In the method, an addition of a square of the displacement and currents in a frequency domain is taken as a cost function. Optimal coefficients of the transfer function of the controller are obtained by minimizing the cost function. Hence, the spillover instability due to the nonlinear vibration will be redriced. Numerical calculations have been carried out for some typical problems. To validate the present method, experimental tests also have been carried out.
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| 5.
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井開, 重男 ; 樫本, 弘 ; 大沢, 恵一 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />This paper presents an actuator with a sensor for controlling vibrations of machines. It consists of a voice coil type electromagnetic actuator connected to piezoelectric sensor and a coil spring.
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The actuator is used for controlling a motor laid on the beam. The disturbance force due to the centrifugal force of the motor is detected by the sensor, and the force which is equivalent to the disturbance force is applied to the motor and the beam by the actuator. This implies that the disturbance force is canceled. The control technique as just mentioned has advantages because it reduces the vibration in the low frequency region, in addition, the actuator becomes compact, and the control force becomes small. But the control is insufficient for controlling the resonance peak. The PD control is available for reducing the resonance peak, but the displacement and velocity sensors are required. In the present article, a method of vibration control of disturbance cancellation combining the PD control is presented in which both the displacement and velocity sensors are not required. The analytical results for obtaining the control current and the response of both the motor and beam have been obtained. To validate the present actuator sensor system and the control method, experimental tests are carried out.
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| 6.
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藤沢, 延行 ; 中林, 貴光 ; 池本, 宏一郎 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />The active control of vortex shedding from a circular cylinder by rotary ocillations is studied experimentally using neural networks, which optimizes automatically the control parameters such as
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the phase lag and the feedback coefficient. This optimization procedure is applied to find out an optimum position of reference probe to attenuate the vortex shedding effectively. The attenuation effect of vortex shedding under this control is investigated by measuring the velocity fluctuations in the cylinder wake and the unsteady pressure distributions over the cylinder surface. It is found that the drag and lift forces acting on the cylinder are reduced under the optimum reference control in comparison with the control under other reference positions as well as those of the stationary cylinder.
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| 7.
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井開, 重男 ; 樫本, 弘 ; 阿久澤, 享 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />This paper presents a vibration isolation mechanism without resonance. The mechanism is consisting of a linear sliders, ball screw, servo-motor and a table in which there is no spring
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element, so the table behaves like a rigid body. In the mechanism, the servo-motor rotates the ball screw with the same displacement as the base displacement in the opposite direction. Hence the disturbance is canceled. A well known relative displacement feedback control method was first discussed, and it was shown that the method was insufficient for isolating vibrations, then a method of disturbance cancellation was presented. To validate the present mechanism and the control method, experimental tests were carried out for a model of the mechanism.
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| 8.
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長屋, 幸助 ; 来栖, 明法 ; 井開, 重男 ; 志谷, 佳久
概要:
application/pdf<br />Journal Article<br />The vibrations of a structure having a vibration absorber without damper vanish at the anti-resonance frequency theoretically. Hence if the rigidity of the absorber is controlled to produce an
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anti-resonance state according to the forced frequency, the vibrations of the structure can be deleted for sinusoidal forces. However, external vibration force involves higher modes, in general, so the structure is excited by various frequencies. Hence it is difficult to delete the vibrations using the anti-resonance procedure. This paper presents a method to control vibration of structures by combining the auto-tuning control of anti-resonance and optimal dynamic absorbers. Theoretical results under the control have been presented. To validate the present method and the theoretical results, experimental tests have been performed.
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| 9.
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長屋, 幸助 ; 福島, 俊之 ; 井開, 重男 ; 金野, 英介
概要:
application/pdf<br />Journal Article<br />A method of vibration control for a column carrying a mass at its tip subjtected to earthquakes is described. A vibration control mechanism consisting of a gear train for the column is also
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described. Experimental tests have been performed for a model of the present mechanism. It is shown that the vibration displacements and the moments in the column are reduced significantly in comparison with those in a conventional column without the mechanism. In the present column, energies for controlling vibrations are not required because of the use of earthquake force as a control force. Therefore, the column has advantages over the columns having an active vibration control system.
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| 10.
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小林, 幸徳 ; 藤田, 聡 ; 長井, 直之 ; 片山, 圭一 ; 萩原, 一郎 ; 佐藤, 勇一 ; 山本, 圭治郎 ; 大熊, 政明 ; 須田, 義大 ; 栗田, 裕 ; 野波, 健蔵 ; 長屋, 幸助
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| 11.
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長屋, 幸助 ; 井開, 重男 ; 福島, 俊之 ; 来栖, 明法 ; 樫本, 弘
概要:
application/pdf<br />Journal Article<br />A solid-type piezoelectric actuator generates a large force, but the generated displacement is significantly small. In particular, the actuator has a large hysteresis between a control voltage and
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the control displacement. Hence the application of the actuator has been limited to some special areas. This paper presents a linear piezoelectric actuator without hysteresis. The actuator presented has linearization control circuits and a displacement enlargement mechanism made of elastic hinges, so that the generated displacement is in the range of displacements required for vibration control of machines. To control the actuator, a displacement sensor is used in general, but one of the ends of the sensor must be fixed to a wall. This implies that the application of the actuator is limited. Hence in this paper, an acceleration sensor is used instead of the displacement sensor. This enables us to use the actuator as a conventional linear actuator. Theoretical analysis was given, then experimental tests were carried out to validate the method and the analysis.
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| 12.
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長屋, 幸助 ; 周東, 俊介
概要:
application/pdf<br />Journal Article<br />Three dimensional analytical results for the levitation force of a vibrating high-Tc superconducting levitation system were presented. When the levitated superconductor vibrates, the
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levitation force shows nonlinear relationships with the air gap, amplitude and vibration frequency, so that the convensional models which do not consider dynamic effects cannot be applied. In the model proposed by(Uesaka et al.), dynamic effects are considered, but the critical current is constant. We propose an improved Kim-model which is applicable to vibration problems of conductors. Numerical results for the levitation force were obtained and compared with previously published experimental data. A modeling method for the superconducting levitation system was presented, and the nonlinear spring constants obtained in an analysis which included the effects of air gap, amplitude and frequencies were given. Numerical calculations were carried out for nonlinear vibrations of the system based on the modeling results.
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| 13.
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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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| 14.
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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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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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| 16.
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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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| 17.
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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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| 18.
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長屋, 幸助 ; 石川, 真史 ; 藤沢, 延行
概要:
application/pdf<br />Journal Article<br />This paper proposes a drag-force-type magnetic levitation actuator consisting of pairs of permanent magnets and electromagnets. For general magnetic levitation actuators, there is a nonlinear
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relationship between magnetic force and control current, so that a linear control theory is not applicable. In the actuator proposed, the relationship between the force and the current is linear. This implies that the position and velocity feedback controls can be applied without consideration of interferences. A control method using a combination of techniques of disturbance cancellation and optimal regulation was presented taking into consideration the interference between perpendicular and vertical motions. To verify the applicability of present actuator and control method, experimental tests were carried out.
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| 19.
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樫本, 弘 ; 長屋, 幸助 ; 白石, 明男
概要:
application/pdf<br />Journal Article<br />This paper proposes a method for obtaining stresses in a rod with arbitrary cross section. The rod consists of two infinite straight portions and one two-dimensional curved portion in which
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the cross section varies. A twisting wave propagates from one of the two infinite straight portions to the other via the curved portion. In this analysis, fundamental equations were extended in order to apply them to the non-circular cross section by using the Fourier expansion collocation procedure, and the transfer matrix was derived. At connecting sections, solutions of curved portion and those of straight portions have been connected. Then it is possible to obtain the principal stress and the principal shearing stress at any location.
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鄭, 惟 ; 長屋, 幸助 ; 岡, 三津夫
概要:
application/pdf<br />Journal Article<br />This paper presents an electromagnetic actuator consisting of rectangular permanent magnetic chips and a cylindrical coil, which is applicable to bending moment control of plates. The analytical
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expression for obtaining the control force against the control current is obtained based on the electromagnetic theory. A control method is presented for producing the required deflection of the plate by means of the bending-type electromagnetic actuator. Numerical calculations are carried out for some typical problems which will be of practical importance. It is clarified that the actuator and the method of control presented are valid for controlling plate shapes.
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| 21.
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龍宇, 光 ; 長屋, 幸助 ; 丹羽, 一
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application/pdf<br />Journal Article<br />A very long elastic beam, which is a general model of a long optical fiber, inserted into a long spatially curved tube by means of vibration is investigated. Analytical models and equations are
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established for the forced transversal movement, the axial movement and the flying motion of the continuous wave beam. A kind of recurrence strategy is successfully developed for the forced transversal vibration problem of a very long beam floating on a vibrating surface. The detailed motion behavior of the whole response, called the "subperiodic motion", and the phenomena of changing tension force and different wavelengths are revealed through numerical solutions. Fundamental effects of some basic parameters on the motions of the system are discussed. Appropriate ranges for both the frequency and the amplitude of vibration are discovered to be very narrow. The reasons for the troublesome "stopping-up" phenomenon are clarified. Experimental studies confirmed the theoretical analyses presented.
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| 22.
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藤沢, 延行 ; 田口, 祥和 ; 佐藤, 毅 ; 植村, 知正 ; 長屋, 幸助 ; 井開, 重男
概要:
application/pdf<br />Journal Article<br />Conditional sampling and the point-averaging technique have been introduced to particle-tracking velocimetry using a binary cross-correlation algorithm. This system is applied to the
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measurement of unsteady flow inside a rotating Savonius rotor, and the quantitative nature of the power mechanisms of the rotor at various rotor angles and tip-speed ratios are newly discussed and the usefulness of this techique is demonstrated. It is found that all velocity fields in and around the rotor vary markedly with the tip-speed ratio, and that the separation of Coanda-like flow on the convex side of the advancing blade is delayed by the velocity fields induced by the rotor rotation and also by the production of vortices downstream of the advancing blade.
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| 23.
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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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| 24.
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長屋, 幸助 ; 横田, 勇
概要:
application/pdf<br />Journal Article<br />In the preceding related paper, the authors discussed a plate-type magnetic damper with alternative magnetic poles. The paper presented the analytical expressions of eddy currents in the conductor
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and the damping coefficients for the single row of alternative poles. The damping effects of the damper having alternative poles of a number of rows and columns are different from those of the previous model. The present article discusses the damping increasing mechanisms for the plate-type damper with alternative magnetic poles of a number of rows and columns. The analytical expression for finding the eddy current patterns and the damping coefficient are obtained. Numerical calculations are carried out for some important examples. Since the present article gives the analytical expression and the numerical data of dimensionless damping coefficients, the results may be used directly in the practical design of such devices as vibration absorbers.
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| 25.
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樫本, 弘 ; 長屋, 幸助 ; 白石, 明男
概要:
application/pdf<br />Journal Article<br />An analysis is presented for the dynamic stress concentration problem of an infinite inhomogeneous rod having a discontinuity of the curved portion in which the radius of cross sections varies
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continuously. The rod treated in this study consists of two infinitely straight portions and one finite curved portion of arbitrary curvature. The curved portion lies between the two straight portions. The twisting wave propagates from one of the infinite straight portions to the other, passing through the curved portion. The exact solution for the equilibrium equations for a curved rod has been obtained. The transfer matrix has been derived based on the exact solution and upon considering the internal forces and moments. At discontinuous sections, solutions of curved and straight rods have been connected by adjusting the boundary conditions. As examples, stress concentration factors in circular, elliptical and parabolic arc rods have been obtained.
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| 26.
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龍, 宇光 ; 長屋, 幸助 ; 丹羽, 一
概要:
application/pdf<br />Journal Article<br />The problem of a block repeatedly sliding, jumping and being conveyed inside a vibrating spatial tube is studied. Analytical models and equations are established in considering three kinds of
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motion states : relative sliding motion, flying motion and the bumping process. Precise investigations are carried out for the inclined frictions with component velocities and for oblique impact, which are seldom discussed thoroughly and are easily misinterpreted. The detailed motion of the entire response, called the ""subperiodic motion"", is revealed through numerical solutions. Fundamental effects of some basic parameters on the motion of the system are discussed. Appropriate ranges for both the frequency and the amplitudes of vibration are discovered to be very narrow. Experimental studies confirmed the theoretical analyses presented.
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| 27.
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遠藤, 正規 ; 長屋, 幸助 ; 渥美, 全弘
概要:
application/pdf<br />Journal Article<br />This paper proposes a method for controlling vibrations of a magnetic levitation table. The system considered in this paper is composed of permanent magnet and a permanent magnet with an
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electromagnet. The vibration is controlled by changing magnetic flux density of the permanent magnet by controlling electrical current in a coil of the electromagnet. Two kinds of control techniques are combined. One is the disturbance cancellation control in which the variation of the levitation force is controlled, which corresponds to the external force due to disturbances, and the other is the state feedback control. Experimental tests have been carried out to discuss the validity of this technique. The experimental results show that the technique proposed in this paper is applicable to isolate vibrations, and the transmissibility can be controlled to be nearly zero.
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| 28.
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田, 宏奇 ; 長屋, 幸助 ; 井開, 重男
概要:
application/pdf<br />Journal Article<br />A new magnetic gear transmitting system with an actuator made of an electromagnet is proposed in this paper. The vibration due to the system parameter variations or external disturbance is
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absorbed by means of changing magnetic fluxes of the electromagnet and the controller is designed by variable structure system (VSS) theory. The theoretical expressions of the transmitting torque, magnetic spring constant and control force versus electric current in the electromagnet were derived. Both the simulations and experiments of this magnetic gear system were carried out by means of the sliding mode regulator and were compared with the PID linear control method. The experimental results confirmed the theoretical analyses.
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| 29.
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樫本, 弘 ; 長屋, 幸助 ; 白石, 明男
概要:
application/pdf<br />Journal Article<br />This paper presents a method for solving the dynamic stress concentration of inhomogeneous rods having two-dimensional arbitrary curvature, variable cross section and infinite length
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subjected to in-plane bending wave excitation. In this analysis, the exact solution of the equilibrium equations for curved rods has been obtained, and the transfer matrix, based on the exact solutions with consideration of the inertial forces has been derived. At discontinuous sections, solutions of curved and straight rods have been connected by adjusting the boundary conditions. As examples, stress concentration factors in circular, elliptical and parabolic rods with variable cross sections have been calculated.
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| 30.
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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 discusses free vibrations of a spiral rod with straight portions on a number of supports. Since the spiral portion is a three-dimensional structure, three-dimensional motions are coupled.
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Hence, this paper first presents the transfer matrix for a three-dimensional curved rod with supports, then the transfer matrix of a straight rod with supports is joined to that of the spiral rod. The frequency equations for the rod with consideration of three-dimensional motions are obtained. Numerical calculations are carried out for some typical problems.
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| 31.
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長屋, 幸助 ; 杉浦, 光則
概要:
application/pdf<br />Journal Article<br />Since electromagnetic force is a function of the gap between two magnets, the spring constant has large nonlinearities with respect to the displacement. Hence, the spring constant
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varies significantly with the initial load. This implies that the linear control theory is not applicable in the range of large displacement. To treat a system with variable initial load and large displacement, the present article presents a procedure for obtaining a linear spring by means of a repulsive-type actuator using permanent magnets and an electromagnet. The analytical expression for the linear spring is presented. Experimental tests were carried out, and the theoretical values are compared with the experimental results.
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| 32.
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長屋, 幸助 ; 関口, 肇
概要:
application/pdf<br />Journal Article<br />A magnetic damper in which opposite poles are arranged by turns has great deal of damping effects as compared with a normal magnetic damper. However the reason of it has not been clarified, and the
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analysis has not been reported. To clarify the mechanisms of increasing dampings for the damper, this paper presents an analytical results for the eddy current, and the damping coefficient. Numerical calculations are carried out for some important examples, and the results are compared with those of the normal magnetic damper.
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| 33.
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長屋, 幸助 ; 王, 建春 ; 井開, 重男 ; 藤生, 正樹 ; 上野, 秀洋
概要:
application/pdf<br />Journal Article<br />This paper proposes an actuator consisting of a piezoelectric element, two electromagnets and a spring for controlling displacement of flexible beam with large deflections. The voltage
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pattern for the piezoelectric element and the electric current patterns for the magnets and the relationship between the actuator displacement and the deflection of a beam are presented. The experimental tests are also caried out. It is ascertained that the proposed actuator has some advantages as compared with the general deflection control apparatus using a motor.
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| 34.
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樫本, 弘 ; 長屋, 幸助 ; 白石, 明男
概要:
application/pdf<br />Journal Article<br />This paper presents a method for solving the dynamic stress concentration of two-dimensional curved rods with circular cross section and infinite length subjected to in-plane bending wave
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excitation. In this analysis, the exact solution of the equilibrium equations for curved rods has been obtained, and the transfer matrix, based on the exact solutions with consideration of the inertia forces has been derived. At discontinuous sections, solutions of curved and straight rods have been connected by adjusting the boundary conditions. As examples, stress concentration factors in circular, elliptical and parabolic rods with circular cross sections have been calculated.
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| 35.
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永井, 健一 ; 大佐々, 吉宏 ; 長屋, 幸助 ; 武田, 定彦 ; 谷藤, 克也
概要:
application/pdf<br />Journal Article<br />An analytical method is presented for the bending vibration of a circular dise carrying concentrated masses, introducing a new mode of shape function to the Galerkin method. Deflection of
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the plate is expressed by a product of the mode shape function along radial direction and the circumferential periodic function. The mode shape function is assumed to be the sum of the product of the trigonometrical function and the finite power series. The coefficients of the power series are found to be satisfied by the boundary condition of the plate. Applying the Galerkin method, the number of sets of differential equation with second-order time functions are reduced. It is found that this method gives good accuracy to the natural frequencies within the small number of terms for unknown time functions
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| 36.
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長屋, 幸助 ; 山口, 俊澄
概要:
application/pdf<br />Journal Article<br />This paper presents a method for solving eigenvalue problems of various phenomena which are governed by the Helmholtz equation with an arbitrarily shaped outer boundary and a number of
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eccentric boundaries of arbitrary shape. In the analysis, the outer boundary condition is satisfied by means of the Fourier expansion collocation methed using the exact solution of the equation of motion. To satisfy the inner boundary conditions, the point restraints are added to the equation of motion, and the inner boundary conditions are satisfied by making use of a point-matching procedure. The equations for finding the eigenvalues are derived, and numerical calculations are carried out for cases of elliptical outer and a number of elliptical inner boundaries, and polygonal outer and a number of elliptical inner boundaries.
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| 37.
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長屋, 幸助 ; 平田, 康夫 ; 鶴見, 豊明 ; 武田, 定彦 ; 永井, 健一 ; 谷藤, 克也
概要:
application/pdf<br />Journal Article<br />Stresses in elliptical-cross-section coil springs become small as compared to other springs used in practical machines at a certain aspect ratio. This article presents a simplified stress
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expression for designing the elliptical-cross section coil springs. The stresses obtained by the present design formula are compared with those obtained by numerical methods. It is ascertained that the present formula is applicable to design the elliptical-cross section-coil springs.
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| 38.
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長屋, 幸助 ; 平田, 康夫
概要:
application/pdf<br />Journal Article<br />This paper presents a method for designing a shape-memory alloy coupling between rods subjected to axial or torsional forces. The design formula is obtained by using the stress-strain
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relation. Since the coupling work is simple, the coupling has advantages for building members in dangerous zones. However, since the coupling force is not sufficient, it is disadvantageous for impact loads. To design coupling under consideration of impacts, this paper also discusses the transient response of the coupling due to various impact loads. Numerical calculations were carried out for some sample problems.
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| 39.
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長屋, 幸助 ; 山本, 哲也
概要:
application/pdf<br />Journal Article<br />This paper discusses a method for the optimal active vibration control of a plate using piezoelectric actuators. The analytical results under the optimal control were obtained by combining the
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eigenfunction procedure and the optimal active control theory. Numerical calculations were carried out for a clamped circular plate with concentrated masses which was controlled by bending moments generated by the piezoelectric actuators. It is confirmed that there is an optimal location for the actuator in each mode.
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| 40.
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谷藤, 克也 ; 永井, 健一 ; 長屋, 幸助
概要:
application/pdf<br />Journal Article<br />The running vibration of a bogie car is considerably affected by its operation speed. This paper describes the results of a calculation analysis on the vertical vibration of a Shinkansen
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electric car at the speed range up to 510 km/h, assuming a drastic speed-up of the Shinkansen. The vibration of each natural modes, except the body-bending mode, tends to increase uniformly with the operation speed. The vibration of the first body-bending mode varies greatly due to the averaging effects of the track roughness through the length between truck centers in the car, and it deteriorates the riding comfort further in the speed ranges near 270 km/h and higher than 450 km/h. As an example, the flexural rigidity of the car body is examined to determine countermeasures suitable for 270 km/h operation.
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| 41.
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永井, 健一 ; 渥美, 全弘 ; 杉山, 晋一 ; 長屋, 幸助 ; 谷藤, 克也 ; 武田, 定彦
概要:
application/pdf<br />Journal Article<br />This paper presents analytical results of non-linear vibrations of a traveling beam levitated by magnetic forces. The problem is modeled as the Euler-Bernoulli beam with a variable cross section
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supported by non-linear springs. The beam and the springs move on an undulated line. Introducing a new mode shape function which is expressed as the product of the trigonometric function and the power series truncated to the fourth order and utilizing the galerkin procedure, basic equations are reduced to the coupled non-linear equations. The steady state solutions of the beam was obtained using the harmonic balance method. It is found that the non-linear responses show the type of soft-spring, the unsymmetric support of the spring or the unsymetric cross section to the mid-point of the beam show large amplitude vibrations of a rotating motion and that of a translating motion in relatively large frequency range.
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| 42.
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長屋, 幸助 ; 武田, 定彦 ; 佐藤, 淳 ; 井開, 重男 ; 関口, 肇 ; 斉藤, 登
概要:
application/pdf<br />Journal Article<br />This paper proposes a thrust bearing lubricated by a magnetic fluid under a magnetic field. The critical pressures of the bearing versus the magnitude of the magnetic flux densities have been
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investigated experimentally. It is clarified that the critical pressures of the proposed bearing are larger than those of the normal lubricant bearing under high speeds.
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| 43.
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長屋, 幸助 ; 武田, 定彦 ; 永井, 健一 ; 佐藤, 淳 ; 杉浦, 光則 ; 佐川, 竜一郎
概要:
application/pdf<br />Journal Article<br />This paper proposes a two-dimensional displacement sensor which is available to detect high speed phenomena such as high frequency vibrations. The sensor consists of a laser, polarisers, a beam
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splitter, solar cells and clean plates in which an index of double refraction varies in one direction. Since the clean plate as just mentioned has not been produced, this paper applies thin films sandwiched with a magnetic fluid, and the double refraction is generated by using permanent magnet. In this system, the laser beam propagating from the moving body is divided into two beams by a beam splitter, and the divided beams pass through the two clean plates whose refraction axes are in right angles with each other. An intensity of the laser beam after passing through the clean plate is detected by a solar cell. Then the position of each beam is decided by the intensity of the laser beam. Experimental tests have been performed to verify the principle as just mentioned.
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| 44.
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長屋, 幸助 ; 荒井, 徳幸
概要:
application/pdf<br />Journal Article<br />This paper proposes an actuator in the magnetic levitation system using a permanent magnet and an electromagnet. In this system, the gravity force of the masses is supported by a strong permanent
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magnet in which two identical poles face each other. The vibration due to external disturbances is controled by use of the electromagnet by changing magnetic fluxes of one of the permanent magnets. The analytical expressions for obtaining the levitation force, spring constant and the control force versus the electric current in the electromagnet were derived using the equation of the electromagnetic theory. Numerical simulations under the control using the optimal regulator for the magnetically levitated boby were carried out. To verify the present theoretical results, experimantal results were also obtained.
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| 45.
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長屋, 幸助 ; 大沼, 浩身 ; 佐藤, 淳
概要:
application/pdf<br />Journal Article<br />This paper discusses effects of viscous pumping in a magnetic fluid seal under a rotating load. The Reynolds equation was presented for the seal based on magnetic fluid mechanics, and the
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expressions for obtaining pressures in the seal, eccentricities of the rotating shaft due to the viscous pumping and seal pressures were given. Numerical Calculations were carried out for some sample problems, and the effect of magnetic flux densities on the pressure in the seal and the seal pressures were clarified.
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| 46.
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長屋, 幸助 ; 桜井, 高志
概要:
application/pdf<br />Journal Article<br />This paper presents a method for obtaining the frequency equation for a circular plate with a number of eccentric circular inner boundaries. In the analysis, the exact solution which satisfies
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the outer boundary conditions was applied, and the inner boundary conditions were satisfied by means of the point matching-method under consideration of the symmetry of the vibration modes. Numerical calculations were carried out for a clamped circular plate with two or four eccentric circular clamped edges and for the plate with two eccentric annular supports.
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| 47.
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永井, 健一 ; 荒井, 徳幸 ; 長屋, 幸助 ; 武田, 定彦
概要:
application/pdf<br />Journal Article<br />An analytical method is presented for free flexural vibrations of a cantilevered beam with a concentrated mass, introducing the new mode shape function to the Galerkin procedure. The mode
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shape function is expressed with the sum of the product of the trigonometrical function and the finite power series truncated with the fourth order. The trigonometrical function expresses the form of the higher mode of vibration. The coefficients of the power series are determined by solving the homogeneous equations for the boundary conditions of the beam. Applying the Galerkin method, the sets of differential equation in a time function are reduced. It is found that this method gives good accuracy to the natural frequencies and the natural modes of vibration within the limited number of terms for unknown time functions.
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| 48.
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武田, 定彦 ; 長屋, 幸助 ; 永井, 健一 ; 井開, 重男
概要:
application/pdf<br />Journal Article<br />This paper presents theoretical and experimental results for the steady state response of a relaxation-suspension system considering the unsymmetrical damping force under periodic excitation.
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the unsymmetrical damping force has two different values in period of the stroke velocity. In the analysis, exact solutions are obtained by considering the continuity of the response at the boundary in which the damping force varies. Numerical calculations are carried out for various values of the ratio of the damping coefficient. It is found that the reference line of the vibration in the relaxation-suspension system maintains a constant value within the range of the high frequency ratio, while the reference line in the direct-suspension system varies proportionally to the change of frequency ratio. The experimental values agreed fairly well with the theoretical results.
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| 49.
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永井, 健一 ; 長屋, 幸助 ; 武田, 定彦 ; 中村, 欣明
概要:
application/pdf<br />Journal Article<br />Analytical results are presented for nonlinear vibrations of a stretched string connected with a laterally movable end mass at one end. Applying the modified Galerkin method to the basic
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equations, a set of ordinary differential equations with cubic nonlinearity is obtained. The steady-state response is determined by the harmonic balance method. Numerical calculations are carried out for the various values for the end mass to the string and the geometry of the string. It is found that if the mass of the end mass increases to greater than that of the string, the resonant response in the first mode of vibration can be treated as a linear vibration up to a sufficiently large amplitude. However, the resonant curves in the higher mode of vibration show responses with a strong nonlinearity within a small amplitude. The increment of the cross section area of the string also gives a strong nonlinearity to the response in every mode of vibration.
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| 50.
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長屋, 幸助 ; 武田, 定彦 ; 井開, 重男 ; 永井, 健一 ; 松本, 康臣 ; 塩野, 二朗
概要:
application/pdf<br />Journal Article<br />This paper proposes an active control damper using an electromagnetic fluid, and presents an expression for obtaining the damping coefficient of the damper. The damping coefficient has been obtained
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by using the solution of the equation for the electromagnetic fluid which includes both Navier-Stokes' equation and Maxwell's equation. Numerical calculations have been carried out for some sample problems, and the effects of sizes of the damper and the magnetic flux density on the damping coefficients have been clarified.
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