Among high-speed railway systems, the superconducting maglev train is an innovative transportation system, in which trains are levitated and driven at speeds of up to 550 km/h. But in case of quench of superconducting magnet, vehicles are forced to touch down on the guideway. For safe landing, we developed the new equipment named “Emergency Wheel”. Our process of development is as follows : (i) To know the maximum load for the landing, we simulated the electromagnetic power and dynamics of vehicles. (ii) Each element of emergency wheel was developed and tested in a factory. (iii) Quench tests were conducted on the Yamanashi Maglev Test Line and results showed a good accordance between simulation and test. Through the study and development of emergency wheel, we established a design method of safety equipment for Maglev.

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The thermal transfer print method is to print ink on the surface of paper by pressurizing ink and paper directly with a thermal head, and heating the places to print. A principle of the thermal transfer printing is similar to that of the offset printing. A tribological contact problem occurs in the offset printing. Thus the thermal transfer printers are suffering from the similar contact problem between the ink and the paper since the surface of the plain paper has roughness and it is very difficult to make the contact situation constant at all time. It is necessary to deeply understand the contact between paper and the solid ink to achieve the high-resolution printing on even the rough plain paper. So far the stylus type and the laser type profilometers were used to evaluate the printing quality for various papers. However there is no attempt to examine the printing quality, optical density, from the view point of real contact area. Then, the relationship between the optical density and the real contact area on the paper side was experimentally obtained in this paper with a contact microscope. As a result, the correlation could be found between the optical density and the real contact area.

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This paper describes the authors' recent work which includes : (1) Performing some improvements to make the LM measurement device developed previously applicable to precisely measuring a small size motion trajectory of machining center with high feed rate ; (2) Applying the improved device on a machining center to test circular and linear interpolation motion trajectories within a small area, and discussing the relation of motion accuracy with movement size and feed rate for the machining center. The results of experiments sufficiently demonstrate the effectiveness of the improved LM device.

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The experimantal study has been conducted for several years to investigate the nonlinear psudo-statical and dynamical behaviors of a viscoelastic body described by the fractional derivative law. Pre-stress due to pre-displacement induces higer damping capacity during sinusoidal excitation. In order to understand this behavior, nonlinear statical and dynamical models are considered. The authors establish and propose the appropriate models to describe the behavior of the fractional derivative viscoelastic body. The nonlinearity having second order term with respect to pre-displacement for pseudo-statical compressive displacement and the nonlinearity having exponential term with respect to pre-displacement for sinusoidal excitation are found to be appropriate to describe the viscoelastic damping coefficients. Some discussions on the values of the viscoelastic damping coefficients and how to model a unified force-displacement relation covering from lower to higher wide frequency range are given.

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The dynamic absorber has been widely used for suppressing vibration in structures. In practical application, the optimal tuned absorbers are designed and used in terms of natural frequency and additional damping so that resultant frequency response may become fully reduced. Among various type of dynamic absorbers, the pendulum type is preferable due to its simple constitution and performance reliability. However, damping performance of ordinal pendulum system may be influenced by levels of excitation because of intrinsic nonlinearity in system which leads to slight change in natural frequency. The present paper deals with a study of new type pendulum dynamic absorber. It is known that pendulum moving along cycloidal curve strictly keeks uniform period. Both analytical and experimental investigations show that a strict optimal damping condition can be satisfied in cycloidal pendulum damper, in conjunction with better damping performance compared with normal pendulum.

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Magnetic damper has the advantages of a linear damping force, a non-contact mechanism and being good at hot and vacuum circumstances. However, its damping coefficient is not so large, so that it is necessary to use a force magnifying mechanism in order to obtain a large resisting force. When the damping force is magnified by a magnifying mechanism, the inertia force of a conductor plate is also magnified. This magnified inertia force exerts a bad influence on the effects of vibration suppression for a vibration system in high frequency range. In this paper, two types of vibration systems in which a magnetic damper was attached to a primary mass through a spring were considered in order to make the magnetic damper effective in wide frequency range. The optimum conditions of the damper and the elastic support were analyzed and the frequency responses of the vibration systems supported with the damper were calculated. The trial magnetic damper using a lever-type force magnifying mechanism was made and its resisting force characteristics were measured. The frequency responses and seismic responses of two types of vibration systems were measured using an electrohydraulic type shaking table. The experimental results were compared with the calculated results and the effects of vibration suppression of the magnetic damper and the elastic support were discussed.

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Trucks with independently rotating wheels (IRW) are expected for the use in gauge changeable trains and light rail vehicles. The truck with IRW lacks for self-guidance ability, and then it needs some additional mechanism for running along the track. One of them is active steering mechanism using traction torque difference between two driving wheels on a non-rotational axle. This paper deals with a simulation study that examines a potential of the curving performance of a vehicle with IRW by means of torque difference control between left and right IRWs. The proposed control law, which is composed of a guidance control for tangent track and a steering control for curved one, has a potential to reduce the lateral force of IRW over the wide range of curve radius, especially in sharp curves. In the steering control, the front and rear axles in a truck are steered in the same direction.

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We studied a method for analyzing inelastic seismic motion in piping systems. Some steel materials for pipes exhibit cyclic hardening behavior under cyclic loads. This behavior leads to higher stiffness in piping elements, and higher natural frequencies in piping systems. It is important to consider these effects in order to predict dynamic responses in piping systems. Past studies have shown that cyclic hardening is mainly dependent on two factors, (1) the number of loading cycles, and (2) strain range. Therefore, we extended the Ohno-Wang rule, which is one of the most sophisticated kinematic hardening models, so that cyclic hardening depends on strain range as well as the number of cycles. A stress-strain relationship of the extended model is dependent on the calculated strain range. We applied the extended model to a shake table test on a piping system. The results indicated the extended model exhibited a strain range dependence of cyclic hardening. Compared with the test results, the error in the calculated acceleration was 8%, and it was less than those for the results without considering cyclic hardening. As a result, we found that the extended model could simulate piping behavior with cyclic hardening, which was dependent on strain range.

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Vibrations of a rotor supported by a repulsive type passive magnetic bearing is investigated. First, the restoring force of a repulsive type magnetic bearing is calculated numerically considering the influences of magnetical anisotropicities of the inner and outer magnets. Then, this obtained restoring force is appoximated by the power series expression considering the effect of the rotation of inner magnet. The effect of each pattern of magnetical anisotropicities of inner and outer magnets on the occurence of resonance phenomenon is clarified theoretically and experimentally.

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On a balancing problem of flexible rotors, unbalance of rigid body modes are eliminated with a dynamic balancing machine and each bending mode is balanced in the field with the rotor mounted in its own bearings. Though rigid body modes and bending modes are considered separately on usual steps, simultaneous balancing must be needed for very flexible rotors on which rigid body modes and bending modes are strongly coupled. In this paper, we propose the modal balancing method in which both rigid body modes and bending modes are considered simultaneously. By using this method and a feature of (N+2) plane balancing, flexible rotors can be balanced on a dynamic balancing machine without an expensive field balancing. In experiments, a flexible rotor is balanced by the proposed method and the ordinary influence coefficient balancing method, and the residual whirl levels under these methods are discussed at the first critical speed.

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This paper describes experimental study on suppressing oscillation of a falling water sheet. Falling water sheet flowing over a dam sometimes oscillates at a low frequency. The water sheet oscillation causes vibrations of paper sliding doors or windowpanes of houses in the neighborhood. Experiental results show that the frequency of water sheet is the same as that of the pressure variation in an air chamber behind a water sheet. Therefore, water sheet vibration is closely related to the pressure variation in an air chamber. We show experimentally that water sheet vibration can be suppressed by setting obstacles at the lower end of a falling sheet or by modifying the shape of the upper end of a falling sheet.

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When thin cylindrical shells having freely supported end such as heat-shielding shells of after-burners, labyrinth air seals and annular structures in large diameter pipings are subjected to axial annular flow, an unstable vibration and a fatigue failure are apt to be occurred. In this paper, the unstable vibration of thin cylindrical shells is investigated cconsidering the fluid structure interaction between shells and fluid flowing through a narrow passage. The coupled equation of motion between shells and fluid is derived using Flügge's shell theory and Navier-Stokes equation. Especially, focusing on the higher circumferential vibrations, the unstable phenomenon of thin cylindrical shells is clarified by using root locus based on the complex eigenvalue analysis by using the mode functions obtained by the exact solution. The influence of shell-dimensions and so forth on the threshold of the instability of the coupled vibration of shells and flowing fluid are investigated and discussed.

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This paper studies disturbance cancellation control to suppress vortex-induced vibration of a circular cylinder in a cross flow. The cylinder is supported by two pairs of elastic beams and electromagnets are used as control devices. Fluctuating lift force acting on a vortex-induced cylinder is assumed as a disturbance. An observer is constructed to estimate the disturbance. Two different types of disturbance are assumed to describe the fluctuation of vortex shedding. One is a sinusoidal wave and the other is a wake oscillator represented by van der Pol equation. Simulation and experiments are carried out for the examination of the control performance.

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Although the weight of passengers can be considered as an increment of carbody mass itself in design of train carbodies, it has been shown that the passengers mass does not behave as a mere increase in mass because of the existing coupled vibration between passengers and carbody. This study clarifies the coupled passenger-carbody vibration, and proposes a new model to design light-weight and comfortable railway vehicles using biomechanics. This paper shows experiment of coupled passenger-carbody vibration with a new simulator that simulates the coupled passenger-carbody vibration. Computer simulation using analytical model shows that the experimental result of vibration characteristics can be identified by the passenger model, which has one degree-of-freedom.

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The purpose of this paper is reduction of noise in a rectangular enclosure. A rectangular enclosure is considered that five acoustically rigid walls and a flexible plate. Four microphones are symmetrically set in an enclosure, and four point actuators are symmetrically set on a flexible plate. At first, calculating four microphones' outputs organically, acoustic modes are modulated into four acoustic clusters, which have orthogonality among acoustic clusters (acoustic cluster filtering). Then, driving four actuators organically, structural modes are modulated into “four structural clusters”, which have orthogonality among structural clusters (structural cluster actuation). Moreover, it is revealed that orthogonality is also effective between acoustic clusters and structural clusters, and the specific structural/acoustic interaction is termed “cluster coupling”. Finally, integrating acoustic cluster filtering, structural cluster actuation and cluster coupling, C-ASAC (Clustered Active Structural Acoustic Control) system is constructed. C-ASAC consists of SISO virtually due to orthogonality which clusters hold, so that CPU load in C-ASAC is much lighter than a conventional MIMO.

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Severe random vibration is easily induced to satellite structure during the flight. Ground acoustic test is conducted to verify the structural design and abnormal function of equipments. Prediction of the upper tolerance limit, therefore, can be determined to define the design tolerance in probabilistic sense for achieving the conservative design purposes. This paper deals with the upper tolerance limit of vibration response for the satellite plate under high frequency diffused acoustic excitation. The upper tolerance limit is derived based on the statistical distribution of the vibroacoustic response together with the theoretical description of response variance. The upper tolerance limit for the acceleration level obtained by Statistical Energy Analysis is compared with the existing methods and the acoustic experiment result. The result from comparison shows that the upper tolerance limit presented in this paper yields good estimate of P 95 and P 99 level for conservative design.

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In this paper a wave absorption control of one-dimensional flexible systems such as ropes and beams near boundary is treated. Those systems are approximated by finite difference method. The finite difference equation of motion of the end element influenced by the boundary condition is compensated to be the same as an inner element free from the boundary condition with control for the propagating characteristic solution obtained from the equation of motion of an inner element. As the control law has an irrational function, control filter is constructed by using polynomial curve fitting for the rope system. We confirmed the effectiveness of the wave controller for the running rope by both frequency domain response and time domain simulation as the non-running rope in the previous paper. Beams are also wave controlled by compensating the finite difference equation of motion of the end elements. We confirmed the effectiveness of wave control law for beams by the frequency domain response and the time domain simulation using an imaginary propagating system.

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This paper describes a new hybrid vibration suppression technique for flexible structures using piezoelectric elements. There are two main methods to suppress vibration of flexible structures. One is active vibration control and the other is passive vibration suppression. The former is effective but has stability problems. While the latter avoids such instability, its controlling force is small. Hence, this paper proposes a new hybrid control composed of inductance, resistance and amplifier that is stable and effective. The optimum values of inductance and resistance used in the circuit can be determined by a simple formulation derived by the two fixed points method. This method is verified by experiments. The results demonstrate that the hybrid control is more effective than passive vibration suppression.

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We experimentally and analytically investigated detailed bouncing vibrations of a flying head slider in near-contact regine. In the experiment, we examined the effect of pitch angle on the unstable bouncing vibration in relation to ambient pressure by changing Z-height. As a result, we found that the hysteresis of touch-down and take-off pressure become small as the pitch angle increase even though the trailing spacing decreases slightly. From detailed measurement of the slider dynamics at the threshold of the bouncing vibration, we found that the trailing edge is first attracted to the disk and the first drop of the trailing edge becomes large as the pitch angle decreases. Moreover, we measured the 3-dimensional slider motion by using two laser Doppler vibrometers simultaneously, and found that the bouncing vibration is a coupled vibration between translation and pitch with a small phase shift. From the numerical simulation of a two-degrees-of-freedom slider model by considering a shearing force of the lubricant and micro-waviness in addition to the adhesion and friction forces, we could get a hysteresis of the bouncing vibration and two different instability processes as observed in the experiment.

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In this paper, the path planning considering rotary motion of load is presented for automous overhead crane. First, we give the condition of interference between a rectangular load and obstacles, and a movable area without interference is decided in the configuration space. Secondly, a secure path planning is derived by the potential method based on extended 3-dimensional diffusion equation considering rotary motion. Furthermore, the parameter of suppressing rotary motion in the extended diffusion equation is clarified, and its effect is demonstrated. Finally, Quadratic curved surface interpolation method is proposed to get the smooth path planning, and the effectiveness of the proposed method is demonstrated through simulation results.

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In this paper, the posture and tracking control is presented for autonomous overhead crane. First, a rotary mechanics is developed and formularized. Secondly, an optimal servo controller is designed in order to avoid the obstacles by rotating and traveling. In order to improve the control performance, the preview servo controller, which synchronizes the rotary motion with traveling motion, is implemented. Furthermore, time-varying controller is applied in order to minimize the superficial error between the reference and output. Finally the effectiveness of proposed controller is shown through experiments and simulation.

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Recently, the shortage of skilled workers has required increasing efficiency for the operations of lifting, moving and setting heavy equipments in plant construction sites. For this purpose, we proposed a Power-Assist Lifting device (PAL) which is driven by a parallel wire mechanism, as one of the most effective means for utilizing the unique sensory skills of a human being and the physical power of a machine. The motion control technique of this device is based on the recursive identification of a Jacobian matrix. However, the decreased performance of the object motion caused by the identification error was observed. The objective of this study is to improve this motion control performance. In this paper, a motion control technique that has velocity feedback and estimation of velocities in horizontal and vertical directions is studied.

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This paper considers the positioning control of wafer transfer robots. In order to improve the productivity of semiconductors, the control system for wafer transfer robots is required to achieve high-speed transfer and highly accurate positioning. However, it is not easy to achieve such performance since the robots have non-linear properties. In this paper, we consider the positioning control of the robots by switching controllers which are designed using Loop Shaping Design Procedure. We evaluate the effectiveness of this proposed method through experiments.

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A new type of pneumatic stepping motor, named pneumatic nutation motor was developed. Pneumatic nutation motor consists of some pneumatic cylinders, an input bevel gear and an output bevel gear. Injecting air into each cylinder causes nutation of the input bevel gear, which makes the output bevel gear to rotate. In this report, first, the driving principle and design of this motor are presented. Next, its characteristics are analyzed theoretically. The prototype of pneumatic nutation motor is fabricated and tested. Experimental results are very promising. The features of pneumatic nutation motor are (1) simple structure, (2) big torque and (3) low speed operation.

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In this paper, we report a new type of nutation motor, named the OFD type pneumatic nutation motor consisting of a diaphragm which has some pneumatic rooms, a nutant bevel gear and a fixed bevel gear. Injecting air into each pneumatic room sequentially causes nutation of the nutant bevel gear, which makes the output shaft to rotate through the universal joint and spherical bearing. In this report, first, the driving principle and design of this motor are presented. Next, the prototype of the OFD type pneumatic nutation motor is fabricated and tested. As a result, it is demonstrated that the OFD type nutation motor is (1) small-sized, (2) simple structure and (3) highly durable.

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In this paper, in order to efficiently solve a large-scaled and complicated optimization problem, the framework of applications integration on the Grid is proposed. In the proposed framework, application holders publish their own applications as a service, which provides four basic functions using the GridRPC system. These functions enable end-users to invoke applications and to exchange input/output files among services. Therefore, end-users can design arbitrary applications integration through the wide area network by just selecting services and combining the provided functions. In addition, we also propose the Application Programming Interfaces (APIs). These APIs enable the service to invoke the designed applications integration. Therefore, end-users can solve their own optimization problems by constructing the optimization system. In this paper, we implement the proposed framework and APIs using the NetSolve system, which is one of the GridRPC systems. Through computational simulation examples, it was found that the overhead time of our implementation is very short compared to the calculation time of optimization. We also found that the optimization system of our implementation can be used practically in the wide area network. Therefore, it can be expected that the proposed framework and APIs are efficient for designing the optimization problem solving system on the Grid.

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In this paper, we propose human activity recognition system, which infers the next human action by taking account of the past human behaviors observed so far. We also developed cooking support system by using an LCD touch panel on the kitchen counter and a mobile robot on the floor, which suggest what the human should do next by voice and gestures. Experimental resuls confirmed the feasibility of the inference system and the quality of support.

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This paper describes a remote-collaboration system named Field-AID that alleviates shortages of skilled worker in maintenance field. This system has mainly two functions. The first is a remote-collaborative work support function based on multipoint video/voice communication. The second is a task report recording function that make it possible to record multimedia data on a task report using eXtensible Markup Language (XML). The feature of this system is that a skilled operator can record a task report while remotely instructing and assisting on-site worker. It is expected that the task report recorded by skilled operator can be used as a task manual for un-skilled on-site worker. From a viewpoint of working efficiency, for the set-up work of a system, the evaluation of this system was executed. As experimental results, we obtained the conclusion that the task report recorded during remote-collaborative work support can be used as a task manual. In some cases, the experimental results show that the report as a manual is more effective in shortening working hours than remote-collaborative-support.

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Transparent-resionous-ultraviolet-curting-type Braille (TRUCT Braille) signs are have spread rapidly for printing Braille together with visual characters on various base materials. However, it is not easy to read when printed on base material on which it is difficult for the forefinger to slide. The purpose of this study is to examine the influence of base materials on the TRUCT Braille reading. We used fine paper and laminate film as the base material, and measured coefficient of kinetic friction between forefinger and their base materials. The coefficient of kinetic friction for fine paper was one-third that for the laminate film. As the subjects, twelve acquired visual impaired persons of Braille reader were examined. They were asked to read verbally randomly-arranged characters printed on fine paper and laminate film. Reading time was one minute and was repeated twelve times for each subject. As the results, most subjects could read TRUCT Brailles significantly faster and more correctly when they were printed on fine papers than when they were printed on laminate films. We found that base material influenced on TRUCT Braille reading.

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Recently, many kinds of methodology to regenerate articular cartilage have been developed. It is important to assess whether reconstructed cartilaginous tissue have appropriate molecular-structure for articular cartilage. There are numerous studies about biochemical and biomechanical properties of reconstructed cartilaginous tissue. However the noninvasive or nondestructive assessment of molecular-structure have not been performed on regenerated cartilage. In this study, we established the methodology of nondestructive molecular-structure assessment of regenerated cartilage using NMR spectroscopy, and performed the assessment on regenerated cartilaginous tissue prepared by chondrocyte-agarose culture model. As the results, the 1 H-NMR spectrum of the regenerated cartilaginous tissue showed peaks dominated similarly to chondroitin sulfate solution. In conclusion, this methodology using NMR spectroscopy could be useful for the assessment of regenerated cartilage.

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This paper shows the effect of ultrathin lubricant films between sliding bodies on acoustic emission (AE) signals induced by the sliding friction and discusses the application of the AE techniques to the monitoring of the lubricant films. Experiments were conducted with a ball-on-disk friction tester to measure the AE signals. The ball was a glass ball of 5 mm diameter. The disk was a magnetic disk with a DLC protective layer on its surface, and was coated with PFPE Z-dol 4 000 about 1.5 nm thick. The noticeable AE envelope signals were induced by the local decrease in the mobile layer at the initial stage of the friction test, and then the magnitude of AE envelope signals increased with the decrease of both the mobile and the bonded layers. The AE map, which is a cascade graph of the AE envelope signals measured in time order, was proposed to monitor the time variation of the spatial distribution of PFPE film thickness, and showed that the mobile layer moved to the direction of friction.

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The ball-fixed joint (BJ) is one of the fixed type constant-velocity-joint (CVJ), and it is widely used in front wheel drive systems of the car. For the recent needs of good mileage and lightweight for the car, the compact CVJ that reduced ball size and increased ball number is developed, and mass-produced. Meanwhile, there is a possibility that the solution of tribological subject of long life under high pressure bring more lightweight and compact design. Then the practical development of new grease is generally performed. But because of non-understanding about characteristics of contact surfaces, e.g. relative slip velocity or spin, the development is inefficient. On the other hand, the pole and the equator of the oil stain were sometimes observed on the balls after endurance test of BJ. The solution of the formation mechanism of the pole and the equator is one subject for understanding the characteristics of the contact surfaces. In this paper, the formation mechanism of the pole and the equator is investigated by measuring the rotational motion of the ball of BJ with the hall sensors in the endurance test, and by using dynamic analysis together.

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The effects of ball groupings on the pitching and yawing ball passage vibrations of the rolling guides under low speed operation were studied. In the experiments, the test rolling guides with three types of ball groupings were prepared, and the pitching and yawing ball passage vibrations of each test rolling guide were measured using a laser autocollimator. Moreover, a calculation method of the ball passage vibrations for a rolling guide with an arbitrary ball grouping was presented. The conclusions were obtained as follows : (1) The occurrence of the pitching and yawing ball passage vibrations were affected by the ball groupings. (2) For the occurrence, the time waveforms and the r. m. s. values of the pitching and yawing ball passage vibrations for the given ball groupings, the calculated results based on the presented method were almost matched with the experimental results.

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The novel mechanism CVT (Shaft Drive CVT, S-CVT) was developed by the authors. The theoretical efficiency is calculated to improve the efficiency and the torque capacity of the S-CVT. It is calculated from the components of torque and velocity. The component of torque is calculated from the loss torque of the bearings. The component of velocity is calculated from the shear model of traction oil in EHL contact area. The calculated efficiency gives good agreement with the experimental result. An optimum design of the two disks/rollers was achieved by using above calculation. In case of conical disk/roller, 9.4 Nm of the torque capacity and 2.5 point of the efficiency were improved comparing to the present conical disk/roller. In case of concave disk/roller, though 0.1 point of the efficiency decreased, 30.7 Nm of the torque capacity was improved by comparison to the present. To compare between two optimized disks/rollers, the conical disk/roller exceeds 15% of the transmission power.

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To tailor the characteristics of molecularly thin lubricant films, magnetic disk surfaces coated with nanometer-thick perfluoropolyether AM 3001 lubricant films were irradiated with 184.9 and 253.7 nm ultraviolet (UV) rays. We elucidated the effect of UV irradiation on the interactions between the lubricant and the magnetic disk surface via surface energy, bonded lubricant thickness and lubricant spreading measurements for films with and without UV irradiation. We found that UV irradiation decreased the dispersive and polar surface energies of the lubricant films by 20 and 80 percent, respectively; increased bonded lubricant thickness; and decelerated lubricant spreading. These results indicated that dispersion and polar interactions between lubricant molecules and the magnetic disk surface were strengthened by UV irradiation.

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Web Based Learning (WBL) is becoming increasingly popular in engineering education. Yet, there are very few WBL systems, which enable hands on learning. Remote Laboratory was developed with a Stirling engine as an example. A student designs a connecting rod, and it will be machined by a milling machine in the lab at a distance. The on-site lab attendant installs the connecting rod on the engine and conducts a trial run, which is viewed by the student via Internet video at the remote location. Experiments demonstrated that the Remote Lab deepens the student understanding about the processes from design to manufacture.

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Manufacturing is the key industry of Japan for her economic expansion. In manufacturing, skill plays a very important role, and is indispensable for securing high precision and for high added values. But with the rapid aging of technicians and with the lack of their successors, skill transfer becomes a very critical issue. Distance learning is considered one way to solve the problem, because skill can be transferred regardless of time and distance. Skill transfer system was developed using distance learning approach with scraping as an example to demonstrate the effectiveness of the approach.

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How to measure the mist flow rate ordering 1 mL/h is the key issue to configure the oil feeding system and/or to monitor the quantity of the lubricating oil for MQL engineering. Here, a new algorithm is reported, which is based on a spatial irregularity of scattered light from the mist particles. The flow rate in the tubing is not even, hence the spatial frequency method was considered not to be applicable to it. However, the core image of scattered light near around the center gives a sharp spectrum of the spatial frequency. To obtain the core image, the light source is focused on the center of fubing flow and the scattered light is formed on a linear CCD. The spatial filter consisted of the combinations of the pixels. And the sinusoidal wiegting-function makes it easy to generate a sharp frequency spectrum. The flow rate is estimated by the spatial velocity and the brightness of scattered light from the mist particles. It has the feasibility to construct a flow transducer for the very low flow rate such as lubricating oil with mist flow. To confirm the effect of proposed technique, a trial model is made and tested with several commercial MQL systems. It has a good agreement with the mass measuring method with bottle and tissu. Furthermore at in-line estimation in the MQL machining process, a transient phenomena of mist flow is detected.

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Loosening and fatigue failure of bolted joints are the two most important problems for vehicles that are subjected to vibration loading. Although many fatigue tests have been performed under axial vibration, there have been few tests under transverse vibration. In this study, loosening-fatigue tests under small transvers vibrations have been performed to understand bolt behavior for the long life region. Results show that if a bolt has loosened within 10²-10³ vibration cycles, damage such as crack nucleation at the root of the first thread is not observed. However if loosening does not occur until approximately 10⁴-10⁶ cycles, then a crack is observed at the root of the first thread in all experiments. Loosening occurs due to loss of axial stiffness caused by crack propagation which then leads to bolt rotation. The results also show that the loosening-fatigue life does not depend on the initial clamping force although the loosening-fatigue life significantly depends on the transverse vibration force.

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We studied a 600 dpi high definition thermal print head. Fast thermal response, thermal resistance, uniform contact pressure on print media, and micro process are necessary to achieve 600 dpi high definition thermal transfer print. Therefore, we examined a new structure of a low thermal diffusivity layer on a high thermal diffusivity substrate, and optimum new design of the head shape. As a result, we could drive a 600 dpi thermal print head at high speed and high duty. We studied thermal print head to achieve multi-level tone in thermal transfer printing, which required appropriate heat control of heating elements on the head and varying the amount of resin ink melted by the energized head edge, that is, varying dot diameter as needed. After a series of examination, we came to the conclusion that head form especially the part between a heating elements and head edge is deeply related to the property of the tone. This meant that optimization of the head form was the key to the solution. Thus we have attained multi-level-tone printing by varying dot diameter in 16 levels with the enhanced print head.

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This paper describes the theoretical and experimental investigations of static and dynamic characteristics of four types of high-speed gas film thrust bearings, such as stepped, pocketed, spiral and herring born grooved bearings. The specially designed test rig is used to measure the air film thickness, friction torque, spring and damping coefficients of air film under the high speed operation conditions from 20000 rpm to 40000 rpm. It is verified that the maximum error in the measurements by the present test rig is less than 7%. On the other hand, the measured results are compared with the theoretical results for checking the applicability of numerical analysis method to bearing design. Good agreements are seen between the measured results and theoretical predictions, and applicability of theoretical prediction method is confirmed with experimental verifications.

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Hydrodynamic gas film bearings are widely used for very high speed, lightly loaded rotating machinery such as gas expander, compressor, gyroscope and business machines, etc. In the design of hydrodynamic gas film bearings, it is of cardinal importance to enhance the friction and stability capacities of gas films for keeping the minimum friction loss above a particular level and for minimizing the vibration due to external excitations. Among various types of hydrodynamic gas film thrust bearings, spiral groove and herring bone bearings have an advantage of high stability and load carrying capacity, but the characteristics of the bearings depend on many design parameters. Therefore, when these parameters are designed suitably, it is expected to improve considerably the friction and stability characteristics of the bearings. In this paper, the optimum design methodology is presented to minimize the friction torque and also to maximize the stiffness of gas film for spiral groove and herring bone gas film thrust bearings, and the applicability of the methodology is verified experimentally.

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A new type of aerodynamic foil bearing is proposed here in order to develop the high performance air bearing applicable to the super-high-speed turbo machineries such as a micro gas turbine. The aerodynamic foil bearings with the different dimensions, namely with the different foil stiffness and the different bearing clearances, were designed and were manufactured, and then the rotation tests were carried out for the purpose of clarifying the bearing performances and obtaining the design criteria. From the experimental results, the following facts were clarified. The foil stiffness had the strong effects on the bearing performances. The stability of the rotor was improved as the foil stiffness increased. On the other hand, as the foil stiffness decreased, the load-carrying capacity increased and the movement to the condition of the fluid film lubrication became faster. After the movement to the condition of the fluid film lubrication, the friction torque was kept low and almost constant. The dynamic bearing stiffness was higher than the static foil stiffness except the case of very low foil stiffness. Finally, it was clarified that the excellent performances were achieved by the choice of the adequate foil stiffness and bearing clearance, and the stable rotation up to 100000 rpm, which is one of the main objectives in the present tests, was achieved.

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Micro traction drive is a transmission by using of modified ball bearing. The traction force is generated by the thrust pre-load between inner race and outer race. The driving force is transmitted by using of retainer that is connected to output shaft. Test-drives of micro traction drive have been carried out as single stage type (reduction ratio around 2.0) and as tandem stage type (reduction ratio 7.3). The dimension of the micro traction drive is 10mm inner diameter, and 30mm outer diameter. As a result of the test, we have found that single stage type traction drive can transmit higher torque, higher number of revolution with lower noise and vibration than planetary gear head. Tandem type traction drive has been successfully operated at maximum speed 20000 rpm.

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A Magnetic Bearing Wheel (MBW) with inclined magnetic poles is under development. This paper deals with the analysis of disturbance factors and motion of MBW. In general, disturbance factors of a magnetic bearing is limited to rotor imbalance, and motion of the magnetic bearing is discussed under the action of synchronous disturbance force/moment caused by the imbalance. This imbalance is defined by the radial shift (static imbalance) and tilt (dynamic imbalance) of sensor detection surface against the principal inertial axis of rotor. However, besides the imbalance, there are actually other disturbance factors such as the radial shift and tilt of rotor core surface similar to sensor detection surface, and the distortion of those surfaces so that MBW generates synchronous and harmonic disturbances. In this paper, all disturbance factors of MBW is formulated, and the relation between each factor and disturbance force/moment is clarified. Moreover, it is clarified that there are forward and backward components to the direction of rotor spin in radial harmonic disturbances.

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The influence of the sprayed layer thickness on the rolling contact fatigue of a thermally sprayed alumina ceramics with a nominal composition of Al₂O₃-2.3 mass%TiO₂ was investigated using a two-roller test machine under pure rolling contact condition with oil lubricant. The influence of undercoating of sprayed nickel based alloy on the rolling contact fatigue was also investigated. The thicknesses of the ceramics sprayed layer of the test rollers were O.2, 0.5 and l.O mm. The failure mode of the sprayed rollers was spalling caused by subsurface cracking. In case of the sprayed rollers without undercoating, the rolling contact fatigue strength of the rollers with O.2 mm thickness sprayed layer was the smallest. The rolling contact fatigue strength of the sprayed roller with 0.2mm thickness alumina sprayed layer was improved by undercoating. In case that the failure depth was small as compared with the thickness of the sprayed layer, the effect of undercoating on the rolling contact fatigue strength was little. The depths, where the maximum values of subsurface shear stresses occurred, almost corresponded to the observed depths of spalling cracks.

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The demands for noise reduction of plastic gears in OA machines, etc. were increased recently because of the strong demands of lowering noise level in environment. The usual way to reduce the noise of polyacetal gears, mainly used as plastic gears, was dependent on lubricant additives only. We newly developed low elastic polyacetal by modifying the molecule chain itself with adding lubricant. In this study, we investigated the characteristics of the gears using the new polyacetal above mentioned in operation on various conditions, and found out the profitability in characteristics of those gears by comparing with the gears made by Nylon 12 (PA 12), well known as a suitable plastic material for low noise gears.

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Various clamping methods are used to tighten bolted joints according to its configuration, bolt size, the magnitude of bolt preload, etc. Elastic angle control method is sometimes applied to tighten important structures such as large-scaled diesel engines, where bolt preloads need to be controlled with high accuracy. Its tightening operation is explained in JIS B 1083. However, the relationship between axial bolt force and nut rotation angle and the guideline for the amount of snug torque, shown in JIS, are not necessarily sufficient from the practical point of view. In this paper, an equation relating axial bolt force and nut rotation angle is proposed to improve the accuracy of Elastic angle control method, in which the effects of interface stiffness due to surface roughness and the inclined angle existing at nut loaded surface are incorporated, and its tightening process is comprehensively studied by experiments. Based on the derived equation, a practical tightening guideline is proposed, which is effective when Elastic angle control method is used together with torque control method.

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The shortening of the lead time in all aspects from metal mold design to manufacture is strongly required together with cost reduction. Especially in the automotive sector, there are metal mold materials of 2.4 m × 4.8 m in size with very heavy weights of up to 20 tons. When processing these large metal molds, blank materials are put on a large table of machine tool, and machined under the cutting condition of large house power and low spindle rotation. To cope with the situation, the study proposes a multi spindles and axes metal mold processing machine to save space and improve the machining efficiency. The proposed machine tool has a range of 6 to 9 spindle heads allowing a variety of different curved surfaces to be processed at the same time. It is shown that the machine tool has the potential of shortening processing time less than half of the conventional one.

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