Semi-active seismic isolation systems using controllable friction dampers had been proposed to reduce response acceleration and displacement compared with those of passive systems, although there was the problem that the dampers might fail to generate damping forces due to malfunctions in strong earthquakes. To solve the problem, a new type of controllable friction damper with a fail-safe mechanism was developed in this study. For the damper, piezoelectric actuators were used to make the mechanism simple since piezoelectric actuators are compact, can produce quick responses and produce large forces. Several experiments were conducted to obtain the characteristics of the new controllable friction damper. Moreover, numerical simulations and excitation tests were carried out for the semi-active seismic isolation system using the new controllable friction damper, showing good performance in the reduction of response acceleration and displacement together with higher reliability and safety compared with systems using conventional controllable friction dampers.

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In this paper, we present the results of experimental and analytical studies of the separation of a copper and polyvinylchloride (PVC) mixture using an electrostatic separator. The separator consists of a plate electrode and a conductive conveyor belt, and it can be inclined about two axes with respect to the horizontal plane. Copper and PVC particles obtained from chopped waste electric cables were used in this study. Separation tests were performed on a sample containing 50% PVC and 50% copper using this method. Prior to separation, the mixture is triboelectrically charged. The principle behind the separation technique is based on the difference in Coulomb force acting on the copper and PVC particles. It was found that the separation efficiency depends on parameters such as the triboelectric charging time and the slope of the conveyor belt. It was possible to obtain high purities and recovery rates of copper and PVC.

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A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibration of the roof tiles was measured by the laser doppler vibrometry and the accelerometer, and the practical natural frequency of the roof tiles was analyzed by the method of impulse force hammer test. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. It is concluded that the values of frequencies of the forced vibration for the fluttering coincide nearly with the values of natural frequencies.

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In diagnosing air-conditioning pipe deterioration, it is especially important to inspect screwed parts because their original thickness is thinner than that of straight parts and it is comparatively easy for leakage to occur if there is local internal corrosion. We examined a method of applying an ultrasonic test for the inspection, and proposed a method for detecting internal local corrosions of screwed parts and estimating the size and the position of corrosion with angle probe of surface SH waves. In this paper, we describe the results of experimental analysis on the echo from screwed parts of pipes, and we show the method to detect the internal local corrosion and estimate the size and position by using the edge echo. Finally, we describe the results of tests on artificial corrosion pipes and the limitations of this method.

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Active control in three-dimensional sound field against incoming noise from external noise source is considered. Convergence characteristics are investigated with not only conventionally wide-used Filtered-x LMS algorithm, but also fast transversal filter (FTF) algorithm and frequency domain adaptive (FDA) algorithm. The advantages and disadvantages of each algorithm is examined through simulations and experiments using 1/5 scale model of a general room. Control results are studied also with both fixed noise source and moving noise source, and the difference in the control performance of each algorithm is compared and considered. As a result of simulations and experiments, both FTF and FDA show better control performance than LMS algorithm against the fixed noise source. Also while noise source is moving, FTF shows better results than LMS does.

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This paper is concerned with an application of the boundary element method (BEM) using the dual reciprocity method (DRM) to analyze nonlinear transient heat conduction in anisotropic solids. In this study, because the fundamental solution of this problem has not previously been obtained, the concept (the analog equation method) proposed by Katsikadelis and Nerantzaki is applied. A standard linear partial differential operator, in which the fundamental solution can be obtained, can be extracted from a nonlinear partial differential equation. One can consider the remainder as a body force and solve the equation using DRM. Mathematical formulations of this approach for two-dimensional problems are presented in detail. Two schemes are discussed in this paper: The “isotropic” scheme, in which the operator of steady-state heat conduction in isotropic solids is extracted, and the “anisotropic” scheme, where the operator of the steady-state heat conduction in anisotropic solids is extracted. The proposed solution procedure is applied to a couple of typical examples, and the validity and other numerical properties of the proposed BEM are demonstrated through discussions of the results obtained.

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To provide reliable validation data for computational aeroacoustics methods that predict bluff-body sound, the far-field sound pressure and fluctuating surface pressure were measured in detail for a simplified mock-up model of an automobile door mirror (a quarter-section sphere mounted on a half-circular cylinder placed on a flat plate). The surface flow on the model was visualized using an oil flow method. The Reynolds number based on the upstream uniform wind velocity and the diameter of the half-circular cylinder was varied from 1.4×10⁵ to 2.4×10⁵ for model yaw angles of 0 and 15 degrees. The pressure fluctuations on the model surface and flat plate indicated the existence of large-scale vortical motion with a non-dimensional frequency, calculated on the basis of the model width and the free-stream velocity, of 0.16. The frequency spectra of the sound pressure fluctuations had a weak peak apparently due to the large-scale vortical motion. However, unlike the flow around a two-dimensional circular cylinder, the peak was not intense enough to alter the overall level of the sound radiated from the model. When the model was rotated 15 degrees, the power spectra of the sound pressure increased in the non-dimensional frequency range between 1 and 2.

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This paper describes the phenomenon of flow-induced vibration in a shell & tube type heat exchanger. This type heat exchanger has often been used in the LPG gas carrier ship and has sometimes caused a fretting and finally comes to a fatigue failure. In flow-induced vibration, there are vortex-induced vibrations, fluid elastic instability and buffeting. Experiments are carried out by use of an actual heat exchanger in order to clarify the cause of tube vibration. The vibration of a lot of tubes is measured for various flow rates and the natural frequency and its damping ratio are also measured. As a result, the cause of the vibration of tubes is not the fluid elastic instability and the vortex-induced vibration but the buffeting due to the turbulence of upstream flow. The main reason is that these tubes are supported by many baffle plates with clearance and then the vibration system becomes the nonlinear.

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This paper describes the confirmation of countermeasure's effect for flow-induced vibration in a shell & tube type heat exchanger. This type of heat exchanger has often been used in the LPG gas carrier ship and has sometimes caused a fretting and finally comes to a fatigue failure. In flow-induced vibration, there are vortex-induced vibration, fluid elastic instability and buffeting. In this paper, the clip is adopted as the countermeasure and it is clarified that the clip can suppress the tube vibration drastically. In this experiment, another countermeasure, that is to say, the dummy tube array is also examined. However the fluid elastic instability occurs by use of dummy tube array. The reason is that the dummy tube was supported by baffle plates without clearance. Therefore the damping ability becomes very small and the natural frequency of the tube appears very clearly.

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A numerical method is proposed to calculate dynamic dissipated energy for mixed structures including elastic materials, viscoelastic materials and porous materials. An expression to calculate share of dissipated energy for an each element in the mixed structures is derived. Using this expression, vibration transmission properties are analyzed for mixed structures composed of a porous material sandwiched between a steel beam with a damping material and a resin sheet. Further, a spacer is installed between the steel beam and the resin sheet in the structures, to analyze deterioration of vibration by the sound bridge phenomena.

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We have developed a new control method for a shaking table that compensates the reaction force caused by a specimen in real-time. In this work, we executed a series of verification tests to confirm the effectiveness of the developed method with a large-scale shaking table with a payload of fifty thousand kilo-grams. The reaction force was calculated from the drive force of actuators and accelerations of the table. A compensator was designed to cancel any reaction force with frequency components ranging from DC to ten hertz. The specimen used for the tests consisted of a twenty-thousand-kilo-gram mass and four columns to support the mass above the table. When the specimen was excited with a large acceleration, the columns were deformed to a plastic range. The characteristics of the specimen, therefore, became non-linear. The results of these tests show that the compensator successfully cancelled the reaction force. Therefore, the control method is effective for using a shaking table with a specimen whose characteristics change during excitation.

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In this paper, a two-dimensional isolation table using circular arc springs and a magnetic damper, which has a simple construction, low height and the capability of vibration isolation in every horizontal direction, is proposed. The isolation table is composed of eight circular arc springs, twelve free bears, a magnetic damper, a table board and a base board. It has approximately the same stiffness and damping coefficient in every direction in the horizontal plane. The response acceleration spectra of the isolation table for two kinds of actual seismic acceleration waves are calculated to confirm the effects of isolation on the seismic responses of the table. A trial isolation table was made and its resisting force characteristics were investigated theoretically and experimentally. The seismic responses and the frequency responses of the table which was installed with a mass or a tall furniture-type model were measured using an electrohydraulic-type vibration machine. The experimental results were compared with the calculated results, and the effects of vibration suppression of the table were confirmed.

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The independent micro-grid is considered to be a technology in which maximum distributed energy is realizable. However, there are many subjects, such as the stability of the dynamic characteristics of power and development of an optimal design method. If the fuel cell system of the capacity corresponding to a load peak is installed, equipment cost will be high and energy cost will not be able to get any profile commercially. By increasing the hydrogen concentration at the time of low load, the power-generation efficiency of a city-gas-engine-generator improves, and carbon dioxide emissions decrease. So, in this paper, a micro-grid composed from a proton exchange membrane fuel cell and a hydrogenation city gas engine was investigated using numerical simulation. The system with a small load factor of NEG and with a large load factor of PEM-FC system has few CO₂ emissions. The system which combined base-load operation of PEM fuel cell and load fluctuation operation of hydrogenation city gas engine is the most advantageous for the comprehensive evaluation of equipment cost, power generation efficiency, and CO₂ emissions. When the optimal system was installed into the urban area model of 20 buildings and analyzed, power generation efficiency was 25% and CO₂ emissions were 1,106 kg/Day.

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Characteristics of low-frequency pressure waves radiated from a train passing a Shinkansen viaduct were examined from field measurements based on the manual for measuring low-frequency noise issued by Ministry of the Environment Government in October 2000, using a low-frequency sound level meter (NA-18 A) manufactured by Rion Co. Ltd. Measurements proved that low-frequency noise comprises a hydrodynamic pressure variation and an acoustic pressure wave. The hydrodynamic pressure variation is designated as the train passing pseudo-sound and the acoustic pressure wave is designated as the low-frequency pressure wave. The low-frequency pressure wave is emitted from a line source and is proportional to the 4th-5th power of train velocity and inversely to the first power of the distance from the source to the observation point.

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This paper follows a previous paper in which the flow rate characteristics of a filter fan for an air cleaner was reported. This paper is concerned with filtration performance as well as with sound level performance. Filtration efficiency, which is defined as the ratio of floating particles in air to captured particles by the filter fan, becomes higher as the diameter ratio becomes smaller. The maximum filtration efficiency is 90% in the cases of a radial filter profile with a diameter ratio of 0.35 and an inclined backward profile with a diameter ratio of 0.50. According to the previous paper, the largest flow rate generated in the case of a diameter ratio of 0.50. Then, the sound pressure levels are investigated in three cases of filter profiles at a diameter ratio of 0.50, i.e., a radial profile, an inclined forward profile, and an inclined backward profile. In conclusion, the best profile of the filter fan has an inclined backward filter profile and a diameter ratio of 0.50.

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Vibration characteristics of a structure on which unbalanced rigid rotors are operated are investigated experimentally and analytically. Rotor speeds cannot exceed a critical speed when drive power to each rotor is insufficient. Furthermore, the running speeds of rotors are entrained into a single speed just below the critical speed and the phases of unbalanced rotors are locked so as to excite the structure violently. On the other hand, two or three rotors operated by sufficient power supplies can run above the critical speed and unbalance forces cancel each other, that is, vibration is very small. When four rotors are operated with sufficient power supplies, the phases of unbalanced rotors are not locked for speeds above a critical speed.

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This paper describes experimental and analytical study on the behavior of falling water sheets. Falling water sheet flowing over a dam sometimes oscillates. It in turn causes vibrations of paper sliding doors or windowpanes of houses in the neighborhood since its frequency is low. Experimental results shows that the frequency of water sheet is the same as that of the pressure in the air chamber. Water sheet vibration is closely related with an air chamber behind the water sheet. The vibration can be suppressed by putting a baffle at an appropriate height in an air chamber. Further, water sheet behavior is analyzed. Comparing experimental data with analytical ones we conclude that sheet vibration occurs around the conditions where the work done by the water sheet on the air chamber reaches a maximum.

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Oscillatory wheel load fluctuation of considerable amplitude is observed on high speed railway vehicles such as the Shinkansen. It is considered to be generated through very small irregularity with short wave length on the rail surface, and the frequency of this fluctuation is estimated to be approximately 50 to 60 Hz. Due to off-loading caused by this oscillation, when lateral forces by curve negotiation act on the wheel flange, derailment quotients in excess of conventional safety criterion, which is set at 0.8, are often observed. In order to study the influence of such oscillatory wheel load fluctuation on the derailment, a computer simulation was carried out using single wheelset model, and then the evaluation method of running safety was investigated. From the results of this calculation, it is found that the external forces and moments to cause derailment are little affected by existence of such high frequency wheel load fluctuation, and that the time duration while the derailment quotient continuously exceeds the limit value relates to the height of flange climbing and jumping. This paper proposed a method of safety assessment which is applicable to such conditions.

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The authors have been conducting research on the derailment and overturning of railway vehicles due to earthquakes. Until now, numerical simulation has been used to ascertain the dynamic behavior and running safety limits of vehicles on vibrating track, and the results of such simulation are now used effectively in the design of railway structures. To confirm the validity of the simulation analysis, we carried out an experiment using a full-scale half carbody mounted on a Shinkansen bogie, which was placed on a tri-axial structural vibration test rig. During the test, the carbody, bogie and wheels were seen to jump from the rails, demonstrating behavior against vibration. The simulation analyzed the experimental conditions, and the results agreed with those obtained from the experiment.

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In order to obtain some useful information on rapid process for functional film deposition, TiO₂ film deposition by thermal plasma chemical vapor deposition (TPCVD) method under an atmospheric environment were carried out. The experiment was conducted on the condition that working gas was Ar, working gas flow rate was 20L/min, the spraying distance was varied from 10 to 60mm and spraying time was 5 min. As feedstock material, titanium tetrabutoxide was used. According to the XRD charts, the TiO₂ films formed by TPCVD contained peaks of rutile-type and anatase-type. Beside, from the results of wettability test and methylene blue decoloration test, it was proved that the TiO₂ films had high photocatalytic properties and the properties of the samples came to be high as the spraying distance during deposition became short. From these results, this process was thought to have high potential for rapid functional film process.

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