Electrostatic levitation is achieved with the control system that is characterized by using a variable capacitor mechanism. In the control system, a variable capacitor is connected with an electrostatic actuator in series. A constant high voltage is applied to this connection. The voltage applied to the actuator is controlled by changing the capacitance of the variable capacitor. An apparatus was fabricated for electrostatic levitation. The capability of electrostatic levitation by the proposed control system was verified experimentally.

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This paper presents a new modeling method and a control system design procedure for a flexible rotor using active magnetic bearings. The purpose of our research is to rotate the rotor for passing through critical speeds caused by flexible modes. To achieve this, it is necessary to control motion and vibration of the flexible rotor simultaneously. The new modeling method named as Extended Reduced Order Physical Model is presented to express its motion and vibration uniformly. By using this model, a PID controller to levitate the rotor and a LQ controller to suppress its vibration are designed.

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A control method of realizing negative stiffness that uses local current feedback is modified to widen its operation range. The modified controller changes stiffness from negative to positive for large disturbance. The switching function is realized with a saturation element added to the integrator. The efficacy of the modified controller is shown experimentally.

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Surface acoustic wave (SAW) linear motor is a kind of ultrasonic motors. The advantages of the SAW linear motor is thin structure, high thrust force, high velocity and precise positioning. Relationship between applied voltage and output velocity, however, has non-linearity in a low-velocity area due to friction drive principle. Therefore the SAW linear motor cannot obtain stable driving without feedback control in the low-velocity area. Previously, to realize such low velocity, PWM control and flexible slider structure were employed. Flexible structure was installed to cancel vibration due to PWM carrier frequency. In this research, we change calculation algorithm for slider velocity measurement. As a result, SAW linear motor can be driven at a low velocity of 35μm/s. Additionally, driving characteristics is improved by using a feedforward controller.

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A 3-D Full Scale Earthquake Testing Facility (E-Defense) was built in Miki Hyogo in January 2005 by National Research Institute for Earth Science and Disaster Prevent (NIED). The E-Defense makes it possible to do full-scale 6 DOF shaking tests. The E-Defense reproduces the earthquake wave which was actually observed. The testing model for the E-Defense is assumed about 1200 tons while the shaking table mass is about 750 tons. The mass ratio becomes substantially large, and greatly influences shaking performance. Therefore simulation tools are needed which allow us to understand shaking performance in advance. In this research, we make accurate model of embarkation with modal analysis. So we can reproduce the greatly influences of embarkation in simulation tools.

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In recent years, the connected control method (CCM) attracts attention as a new control method to suppress vibration of high-rise buildings due to strong winds or large earthquakes. The CCM for two building structures arranged in parallel with MR damper has already been presented in a previous research. Therefore we increased the number of building structures to be connected 2 to 4. They are arranged in square and connected with four MR dampers. In this research, each MR damper is located to connect at edges of two building structures to control torsional vibration as well as bending vibration. In this paper, a basic research is presented that shows the effectiveness of the CCM with the MR damper as a passive control device.

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The control of vibration is important for high technology field such as semiconductor manufacturing. In this field, active vibration isolation device has achieved good performance to reduce vibration. But recently, stage device is bigger and stage movement is more quickly. Therefore the reaction force for vibration isolation is bigger and transmitted to the floor. In this study, in order to solve this problem, we developed an active vibration system using inertial force generators. Dual Model Matching control method is adopted for this system. We confirmed effectiveness of vibration isolation by experiment.

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Micro grid energy system is consisted of various kind of electric generator (ex: wind power system that use natural energy, gas engine, storage battery and etc.). These devices are needed to be operated in line for the electricity demand change. Fuel composition also changes in assuming biomass use in micro grid. So, it is important to understand their transient response properties for designing and managing micro grid energy system. In this study, gas engine dynamic model was built to predict transient response and it was also investigated in experiment for existent gas engine. In addition, influence of combustion duration, which was affected by fuel property, on transient response was investigated by using engine dynamic model.

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This paper estimates the principle of two-axis angular velocity measurement in gyroscopic sensor using active magnetic bearing. In the sensor, angular velocities are measured based on the control signals to cancel gyroscopic toques operated to the shaft in the AMB. In measuring two-axis angular velocity at the same time, the control signals to cancel inertial toques must be considered in addition to the gyroscopic toques for precise measurement. However, effect of the considering the control signal to cancel the inertial toque never been revealed. The effect is studied in this paper.

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As a welfare equipment, a seated stairlift is used to go up and down stairs in the home. Recently, the seated stairlift with single rail has been developed to reduce the production cost and the construction time. However, it is necessary to control the seating face in real-time by using an actuator. In this paper, we apply a two-degrees-of-freedom control scheme to improve the control performance. The effectiveness is shown by experiment.

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This paper presents the experimental results for an inverted pendulum with time-delay. The stabilized control system law is constructed with the optimal regulator and distributed-delay control laws. Lumped-delay approximation of distributed-delay control laws gives rise to an unstable closed-loop response. It solves these problems by applying the strictly proper approximations reported by L. Mirkin (2004). It is provided that the inverted pendulum with time delay is stabilized by the distributed-delay control laws with strictly proper approximations in experimental and simulation results.

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A new magnetic suspension using a variable flux-path has been proposed. The flux of the permanent magnet to floator is controlled by moving ferromagnetic plates between them. The lateral position of ferromagnetic plates is changed by an actuator. In the previous works, a 100-g steel ball was supported and controlled in three dimensions using this mechanism. The purpose of this study is to suspend a kg-order object and controlled it in three dimensions. This study shows that a one-kg steel ball can be supported by magnetic suspension using a variable flux-path mechanism.

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This paper deals with analysis for acoustic properties of automotive exhaust system having sound absorbing materials. Elements of the sound absorber having complex density are modeled 3D finite element. It was applied to the automotive exhaust system to verify the accuracy of acoustic analysis. The results show good agreement with results from acoustic experiments. Further, using asymptotic method to the equations of motion, explicit expressions of modal loss factor are derived. And the contribution for modal loss factor can be calculated. Applying the proposed method to the automotive muffler, it enables a more efficient layout of the sound absorbing materials.

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This research deals with nonlinear dynamical behaviors of a rigid bar between a diamagnetic slab and a magnet excited in the horizontal direction. In our analytical modeling, the rigid bar has magnetic dipoles with masses at both its ends, which are nonlinearly supported by electromagnetic forces. Nonlinearly coupled equations of translation and rotation of the rigid bar were described and dynamic behavior of the bar was examined numerically. A combination resonance of the vertical oscillation and the rotation was confirmed by numerical results. This resonance was also obserbed in our experiments.

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Analytical results are presented on chaotic oscillations of a post-buckled clamped beam constrained by an axial elastic spring subjected to combined axial-and-lateral excitations. Equations of the motion of the beam are derived including the term of parametric excitation due to the axial excitation. Nonlinear periodic responses are calculated with the harmonic balance method. Time progress of the beam, including non-periodic response, is calculated with numerical integration. Effects of the amplitude and phase of the axial excitation are carefully examined on the responses of the beam. It is found that transitions between non-resonance, principal and chaotic oscillation are sensitive to the amplitude and phase of the axial excitation. Both in the analysis and in the experiment, transition phenomena between the chaotic response and the periodic response are observed, by switching the axial excitation.

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This paper proposes a novel engine using periodic phase transition of matter between the liquid state and the gas state, namely geysering engine. The geysering engine consists of a closed thermosyphon, a moving part and a working fluid, and it can repeatedly operate without such mechanical structures as flywheels or cranks. Fluorinert is used as the working fluid. The amplitude and the period of pressure oscillation in a closed thermosyphon are measured to find out the characteristics of geysering in terms of an engine. In the experiments, we observed more than 10kPa pressure changes. For obtaining kinetic energy from pressure changes of geysering, we also made a simple geysering engine using a rubber balloon.

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In this research, a new type valve system using a conical spring and an electromagnetic actuator was developed: This system uses a conical spring, and is a low torque in a low-speed rotation. As a result, the energy loss in a low-speed rotation is decreased. However, the jump and bounce phenomena happen in the high-speed rotation region. Those are suppressed by using an electromagnetic actuator. It was confirmed to be able to decrease the load torque by using a conical spring in the experiment. Moreover, it was confirmed that the jump and bounce phenomena were suppressed by using the present electromagnetic actuator.

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Experimental results are presented on chaotic vibrations of a buckled plate with an in-plane elastic constraint at clamped edges. At the boundary of the plate, a couple of opposite edges is clamped for deflection, while the other edges are simply supported.The plate is excited by lateral periodeic acceleration. Chaotic responses are examined by the Fourier spectra, the maximum Lyapunov exponents and the Poincare projection. In the specific regions of the exciting frequency, chaotic responses are generated accompanied with the dynamic snap-through transition from the ultra-subharmonic resonance of 2/3 order and from the sub-harmonic resonance of 1/2 order of the lowest vibration mode. Furthermore, another chaotic response is generated involving one-to-three internal resonance between the lowest and the fifth vibration mode. Contribution of vibration modes to the chaotic responses is analyzed by the principal component analysis.

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Experimental results are presented on chaotic oscillations of a shallow shell-panel with a concentrated mass. The shell-panel is excited by lateral periodic acceleration. Chaotic responses are generated in specific regions of the exciting frequency. Changing the mass ratio and the location of the concentrated mass, the chaotic responses are examined with the Fourier spectrum and the maximum Lyapunov exponent. The Lyapunov exponent of the chaotic response of the shell with the mass takes smaller value than that of the shell without a mass. Contribution of modes of vibration to the chaotic response is analyzed with the principal component analysis. The patterns of the vibration modes which contributes to the chaotic responses are transformed by the concentrated mass.

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This research investigates nonlinear dynamics of a beam supported at both its ends by electromagnetic forces from High-T_c Superconducting bulks, under vertical excitation. Numerical results show some resonance of consisting of pitch motion and deflection, which never gets excited in a linear system. It is a kind of combination resonance. This resonance has nonlinear characteristics such as soft-spring response: the resonant frequency becomes small as the amplitude increases, which leads to the hysteresis phenomenon. Experimental results also show combination resonance. Mechanism of this resonance was discussed from nonlinear coupling of the eigenmodes.

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In this paper, first, the dynamic characteristics of the one-link robot arm driven with a stepping motor are investigated theoretically. The stepping motor was driven by the four-division micro step technique. Then, it is confirmed theoretically that the amplitudes of the vibrating torque of the stepping motor in case of the micro step drive are considerably smaller than the ones in case of the full step drive, and the transient vibrations of the stepping motor in the acceleration and deceleration periods can be reduced by using the micro step drive. Furthermore, the experimental results are demonstrated.

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A vibration isolation control using electromagnetic spring actuator is presented. The device consists of spring type actuator stacked with iron particles layers, the electromagnet the permanent magnet. When base vibrations occur, the electromagnetic force created by the electromagnet isolates vibration of the top of the permanent magnet which lies on the spring actuator. In general, vibration isolation controls need both the displacements and velocities of the vibrating body. But in this research, vibration isolation controls is possible by using the displacements and velocities of the base. Therefore, this control method is straightforward and compact, because it requires no complex control devices.

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A high speed actuator consisting of coil springs with iron layers have been presented, in which displacements of the ends of actuators are controlled by electro magnets. Using the actuators, two dimensional positional control mechanism is presented, that controls the position of the instruction point on the screen by changing the angle of the laser pointer The mechanism consists of two spring actuators as just mentioned, in which one actuator is parallel to X axis and the other to Y axis, sliders, and a laser pointer. The laser pointer is rotated by displacing the springs. The displacement of the direction of X has no dependence on the direction of Y. Therefore, the instruction point can be scanned all over the range by operating the one actuator with high frequency and the other with low frequency. Moreover, the instruction point displaces to the target point by using usual PID control method.

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This paper describes the vibration analysis using multibody vehicle model with a method for calculating the road input from the three-dimensional road model. The three-dimensional road model which produced the frequency characteistic of a road was made with the filtered Poisson process. The contact pressure and contact area affect the road input, for the distribution of the contact pressure and contact area are used as calculation factors in the proposed method. By using the method, the shape of the three-dimensional road were considered and the vehicle vibration could be analyzed.

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Railway truck is necessary to have excellent curving performance as well as high speed hunting stability, but generally they are contrary to each other. "Active-bogie-steering (ABS) Bogie", is one of the methods to realize the compatibility between curving performance and hunting stability. ABS bogie has active steering mechanism only between car body and, bogie frame, and bogie frame is steered by actuators toward "radial steering position", which realizes no "bogie angle shortage". In this paper, the actuator consists of AC servo controlled motor and mechanism with friction is modeled to realize ideal response and tracking ability for desired actuator force. The effective control which compensates actuator friction is proposed and is investigated in experiment. Moreover, calculation of hunting stability for ABS truck by using half body model was compared with other truck model.

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The characteristic of vibration on railway system is that due to multipule wheels continuously passing on railway track and interactions between the wheels influence contact force. Contact force is thought to influence ride comfort and safety of high speed trains. In this paper, from a view point of multibody dynamics, the modeling and the formulation are proposed and we carried out numerical simulation on contact force fluctuation of high speed train in order to investigate the effect of the interactions between the wheels. As a result, it can be pointed out that natural frequency of the wheel/rail system and phase difference of contact point displacement on influence contact force fluctuation.

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In this paper, from a view point of multibody dynamics, the modeling and the formulation for rocking motion of a rigid body system considering contact geometry are proposed. The rigid body system is composed of three rigid bodies. The bottom rigid body has restriction of contact geometry between a support. The formulation for the rigid body that has the constraint is completed by augment method. The formulations for the other rigid bodies are completed by Lagrange equation. When the support is given oscillation disturbance in a horizontal direction, we note the vibration and the rocking motion of the rigid body system. In this case, we discuss an influence of the disturbance and the stiffness between rigid bodies.

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The rammer is used in order to firm the ground. Then the vibration of its handle causes the poor circulation to the hand, and lead to the Raynaud's disease. We consider attaching the multi-particle collision damper in the rammer to attenuate the vibration of the handle. Vertical vibration and the torsional vibration are generated on the handle. Since the handle rotated by the movement of rammer, we focused to the torsional vibration. In this study, the characteristic of this damper to torsional vibration examined through experiments and simulation. A number of particles were put in the cylindrical vessel. In addition, the division plate was installed to colliding the particles. As a result, it turned out that the torsional vibration decreases if the particle of a suitable particle diameter and filling ration of particle for the vessel was filled.

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Impact characteristics of a cue in billiard are evaluated numerically by developing a simple method. It is assumed that the cue and ball are elastic and rigid, respectively. The displacement of the cue is estimated by the finite element method and that of the ball is calculated by solving the equation of motion. The time variation of impact force is estimated by equating these displacements at contact point. The accuracy of the analysis is checked by performing a detailed finite element analysis and an experiment, in which a freely supported cue is hit with a swinging ball. It is shown that (1) the impact force and the ball velocity increase with increase in the stiffness of the shaft, (2) the contact period decreases with increase in the stress wave velocity in the cue, (3) with increase in the stiffness of the tap, the impact force rises rapidly, reaches a large maximum value and falls in a short time (4) the ratio of slip to rotation of a ball during the contact period increases with increase in the stiffness of the shaft and the tap and (5) a peak appears in the time variation of impact force for a soft shaft due to the metal screw in the middle of the shaft.

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This paper describes the evaluation of the performance of multibody dynamic analysis with natural coordinates. The computation time of the developed program was evaluated with multiple pendulums model and pendulums model with branch. Natural coordinates were compared with reference point coordinates in computation time of multibody dynamic analysis. These results showed the difference of the computation time between natural coordinates and reference point coordinates due to the topology of models.

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In the design of push-pull local ventilation systems for fume or plume, it is of great importance to capture the pollutants of buoyant jet in the pull hood opening. To meet this demand, the effect of perfect capturing limit flow ratio on the pull hood Q_2/Q_1 were investigated experimentally for parameters in two-dimensional flow field. There are the pull opening ratio B_3/B_1, the push-pull distance ratio L/2B_1, the push flange ratio F_3/B_1, the pull flange ratio F_1/B_1, plume flow volume ratio Q_3/Q_1, and location (L_p, H_p) of plume as the parameters which are related to the design of push-pull ventilation systems.

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Mean velocity profiles and turbulence intensity were measured in turbulent plane air jet in a Push-Pull ventilation apparatus. Under the speed of jet is constant, we consider how mean velocity distribution and turbulence intensity distribution will change between jet nozzle and exhaust hood with experiment. Furthermore, we consider how plane air jet will be influenced by exhaust speed. When the influence caused by the exhaust speed is seen, (U_1/u^^-_m)^2 is decreased and the locus of the half-velocity points are increased.

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This experimental study aims at investigating the turbulent diffusion mechanism of jets, in particular the relationship between the static pressure and the lateral mean velocity on the development of a two-dimensional air jet. The dimensional jet with three injection velocities (11.7, 23.3 and 35.0m/s) was generated in a two-dimensional wind tunnel. The velocity distributions were measured by X-type hot-wire anemometer. The static pressure distributions were measured by the static pressure probe that was developed in ore laboratory, using a hot-wire anemometer. The result of experiment was that the negative static pressure exists in the turbulent shear layer. It is considered that the entrainment proceed from the negative static pressure by the eddy motion of the turbulent shear layer.

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The influences of the cross sectional shape of the rib on the flow around the rib array was studied by means of experiments and CFD. Four different cross-sectional shapes, namely half square, half circle, right triangle of which hypotenuse facing upstream and right triangle of which leg facing upstream were tested. The length ratio of rib base and gap is 1:2. The flow field was measured by the hot wire and visualized by smoke wire method. Numerical simulation was carried out by Large Eddy Simulation (LES) with Smagorinsky model. These results clarified the influence of the shape of the rib on the process of turbulence generation, the extent of turbulent domain and the contour of vortices.

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The purpose of this study is to measure flow rates with high accuracy by using ultrasound. Experimental study has been conducted on ultrasonic properties which are necessary for the measurement. An automatic measurement system which can measure spatial-temporal sound pressure distributions has been developed. According to Snell's law, the ultrasonic propagation paths can be obtained on the basis of incidence angle, acoustic impedance, basic frequency of ultrasound, and material and thickness of metallic plate. However this law can't be applied to certain cases where an ultrasonic incident wave passes through a metallic plate and turns into a longitudinal wave, a shear wave and a Lamb wave. Consequently the ultrasonic propagation paths have been investigated experimentally at various angles of incidence and plate thickness. The most suitable incidence angle has been determined from the result of measurements, and flow rates will be measured.

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Tracer particles are necessary for Ultrasonic Doppler Method (UDM) as reflectors of the ultrasonic wave. Though the nylon powders are used as reflectors in the experimental apparatus, the use of them is difficult in the measurement of the actual rivers. Therefore, the coverage of UDM is limited. Then, we think that microbubbles can be used for the flow rate measurement of the actual rivers as reflector of UDM, as their follow is good in the flow field. In addition, they have profitable characteristics like the water quality purification and the physiology revitalization of the aquatic life. This research' mixed microbubbles with open channels, and measured with UDM. And we experimentally obtained the flow velocity distribution, and the relation between the bubble diameter distribution and the amount of inhalation air.

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Flow separation is mostly an undesirable phenomenon and boundary layer control is an important technique for flow separation problems on airfoils and in diffusers. The vortex generator jet method is an active control technique which provides a time-varying control action to optimize performance under a wide range of flow conditions because the strength of longitudinal vortices can be adjusted by varying the jet speed. In this study, an adaptive separation control system using vortex generator jets with rectangular orifices has been developed. The separation control system can be practically applied to the flow separation control of a two-dimensional diffuser. It was confirmed that our separation control system could adaptively suppress flow separation for the flow fields caused by some changes in freestream velocity and the divergence angle of the diffuser. Furthermore, our system has the ability to operate just before the onset of separation.

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The objective of the present paper is to investigate the flow characteristic in the vicinity of a plasma actuator and to obtain the separation control over a backward facing step by the plasma actuator experimentally. The plasma actuator is an electric device designed for flow control using electro hydrodynamic effect. By applying the pulse voltage signal at E=-5〜7kV and f_p=5kHz, the surface plasma is formed in the vicinity of the actuator. The Reynolds number based on tunnel height is set at 1600. The velocity near the actuator is greatly increased in one direction by the surface plasma, and the large-scale downward flow exists in the upstream region of the actuator. It was proven that the flow separation is greatly suppressed by applying the plasma actuator in the backward facing step flow.

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To investigate the generation mechanism of tonal-noise from a rear-view mirror, tonal-noise radiated from the backward-facing step with surface bump was measured with a low-noise wind tunnel. Noise level of tonal noise depended on the distance between the trailing-edge of the bump and the edge of the backward-facing step. The frequency of the tonal-noise can be estimated with the prediction model based on the characteristics time of sound propagation and vorticity convection. The predicted frequencies were in good agreement with the experimental ones.

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In order to clarify the generation mechanism of aerodynamic sound from a cavity, noise and flow fields around a cavity were measured with a dynamic PIV system. To capture the vorticity field of high speed flow, frame straddling method was utilized with high-speed CCD camera and infrared Laser. Instantaneous aerodynamic noise and vorticity field were measured by developed system. As a result, the strong noise was generated when the eddy passes through the edge of the forward facing step. At that time, the eddy was deformed. On the other hand, noise level was the lowest when the two eddied were observed in the cavity. It indicated that the spatial deformation of eddies play an important role with the aerodynamic noise generation.

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Turbulent channel flow over a backward-facing step is investigated experimentally under controlled by suction through a slit at the bottom corner of the step. Suction is continuously performed and the direction of suction is perpendicular and horizontal to the main flow. The suction flow ratio is varied from 0.00 to 0.15. The wall static pressure and local heat transfer coefficient are measured behind the backward-facing step. The velocity profiles and turbulent quantities are measured by PIV. It is found that the pressure drop at the step is reduced and the heat transfer coefficient in the recirculating region is improved by suction. The difference of suction direction dose not effect to the heat transfer and fluid flow characteristics.

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