Vibration characteristics of hexagonal bars in liquid were experimentally and analytically studied to verify analytical methods for fluid-structure interaction vibrations. Vibration experiments were conducted to acquire precise data of natural frequencies and eigenmodes of a seven-hexagonal-bar system. The seven hexagonal bars were installed in a tank, arrayed in a hexagonal matrix and immersed in water. The information from eleven modes out of the predicted fourteen modes was obtained through the experiments. The experimental results were compared with analytical results calculated by two finite element models. Three-dimensional analysis, in which the finite length of hexagonal bars was considered, yielded results which agreed well with experimental ones. Two-dimensional analysis, in which the virtual mass was assumed to be constant along the bar axis, overestimated the virtual mass especially for the predominant mode to base excitation. These results showed that a three-dimensional method is required for vibration analysis of the experimental model dimensions.

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During the last few years, as we enter a new era of a high-level information-oriented society, the number of buildings having multiple functions has been increasing. Seismic isolation technology can protect not only the structural elements of a building but also its primary function from destructive earthquake motion. It is with such background that many types of earthquake isolation floors or systems have already been developed and have spread throughout in Japan. Almost all isolation floors/systems developed with especially for critical equipment such as computer systems so far consist of coil springs to provide equipment a designed natural frequency and energy-absorbing devices such as friction dampers and oil dampers. However, these types of earthquake isolation floors or systems may become expensive although they perform satisfactorily. The friction pendulum bearings developed in this program can solve this problem. This device consists of an articulated friction slider which moves on a spherical concave surface and provides the supported equipment with a designed frequency obtained by a radius of curvature and gravity. The articulated friction slider dissipates energy as a friction damper. In this paper we conducted shaking table tests and theoretical analysis in order to investigate the performance of isolation and the restoring force characteristics of the earthquake isolation system using the friction pendulum bearings.

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This paper describes the experimental study of suppressing torsional vibrations of a rotor by attaching a hollow cylinder partially filled with liquid. The hollow cylinder is divided into identical chambers by radial walls. The effects on vibration suppression of the amount of water, the height of a cylinder and the number of sectioned chambers are examined. Experimental results show that the tuning condition for the amount of water depends on the number of chambers. Analytical results are compared with experimental ones.

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In order to control low-frequency automobile engine vibration in rolling and bouncing modes, a design method for the engine mounting system using hydraulic insulators was developed. In this method, the design optimization theory for each hydraulic insulator and the theory for determining equivalent mass at mounting points for various modes, which were developed by the authors, are applied to integral sustem optimization. Computer simulation results show that the resonance pikes can be effectively controlled by hydraulic engine mount systems using this design method.

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In this study, noise reduction in a C-frame type of turret punch press has been investigated experimentally from the point of view of structural design. Many studies were carried out on the noise reduction by improving the shape of the die and punch, and some researchers reported that the noise is radiated from the main frame of punch presses when the punch breaks through a sheet metal. In this study, experimental modal analysis is applied, and a scale model is mainly used. Some improvements are proposed to reduce the noise. Main frames were filled with cement concrete to reduce the local vibration, and a couple of mass dampers were attached to the side surface of the frame to damp the tuning vibration mode. From the experimental results, the effectiveness of these improvements was confirmed.

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A new type of hybrid mass damper for response control of tall buildings was tested by using large-scale models of the mass damper and a building. The mass damper can work as an active one to effectively control relatively small vibrations of a building caused by winds and weak earthquakes. At the same time, it can work as a passive one against medium and strong earthquakes. The harmonic excitation tests were carred out for a mass damper model with a 5t moving mass supported by an XY-motion mechanism and equipped with a hydraulic actuator in each direction which could change over from a normal actuator to an oil damper in the inverse direction as well. The model was installed on the roof of a 6-story building model of 19m height and 470t weight. The tests showed that the mass damper could achieve a 90% reduction in the 1st-mode response of the building by the active control, and a 60% reduction by the passive control. It was confirmed that the mode switching did not give the building impulsive responses.

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This paper presents the dynamic characteristics of flow-induced vibration of a circular cylinder set with yawed angle against the flow direction. The effect of the cylinder bounded by a spiral fin or wire on the suppression of flow-induced vibration is investigated, i. e., yawed angle, spiral pitch angle and number of spiral threads. As a result, the cylinder with the spiral fin is most effective for the damping. Also, the cylinder bounded by a pitch angle of 50°and 2 spiral threads is most effective.

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Since active magnetic bearings have been employed in turbo-machinery, a corresponding simulation technique combined with rotor dynamics and a controller network is required for design, controller tuning, and so on. This paper presents the principle of the simulation method and its applications to stability estimation, unbalance responses and frequency response of a servo control system. The rotor system is reduced to a small model by the quasi-modal modeling that we have developed. The control network is expressed by the usual state equations. Both the models are then combined in a global system equation for the simulation analysis. In addition to the usual control law, e. g., PID, the observer based state feedback and so on, the developed program is capable of covering the tracking filter with rotational speed and cross talk between X and Y channel control, which are related to empirical knowledge of the rotor vibration control. Some examples of the numerical simulation are presented for demonstrating practical applications of the developed program.

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The controller of active electromagnetic bearings which enables to cancel out external forces is effective for reducing vibrations of a flexible rotor. It is very time-consuming to estimate external forces by an observer or an inverse system even if using digital signal processor. Therefore it seems to be difficult to apply this control to high speed spindles. In this paper, considering that estimation has not to be real-time in case that external forces are sinusoidal, we design the digital controller which cancels out unbalance forces under relatively short sampling period using previously calculated unbalances. Simulating unbalance responses of an flexible rotor system, we find out that for reducing resonance vibrations this control is superior to the PID control.

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Experimental identification of a mechanical system with character matrices is practically convenient as it is possible to express a complicated system with a few degrees of freedom. However, the result is often affected by the measurement noise, and the elements of the obtained matrices sometimes do not directly correspond to the physical system. The former has lately been discussed and improved, but the latter remains a problem. In this paper we first discuss the physical meaning of the obtained matrices, whatever the identification method may be. Next, we propose an improved method based on an assumption that the system includes only proportional damping. The method was examined both numerically and experimentally, and proved to be practical.

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This paper deals with a practical experimental modal identification method for large-scale structures such as boiler plants in thermal power stations. The proposed method utilizes seismic records which include multi-directional base acceleration data, and multi-I/O identification is carried out. This method is composed of two stages : (1) processing frequency transfer functions by multi-variate autoregressive (AR) spectral analysis, and (2) curvefitting to extract modal parameters. This method is examined using time series data of seismic response simulation, and a comparative study is carried out between multi-input and single-input identification. It is shown that multi-I/O identification is essential for asymmetrical large structures such as boiler plants. This method has actually been applied to in-situ seismic observation data of a boiler plant in operation. As a result of these investigations, this kind of modal identification has proven to be an effective tool for dynamic modeling of large scale structures.

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This type of device is simple in construction and has a high capacity to compensate automatically for the unbalance of a rotor above the critical speed. Below the critical speed, however, the displacement of balls introduces an unbalance, and a violent self-excited vibration takes place in the neighbourhood of the critical speed. To cope with these problems, this paper deals with the theoretical and experimental investigations on the static balance and the transient response at a constant acceleration of an automatic balancer using three or more balls placed in the race which is partitioned into equal sectors. It is shown that partitioning the race is very effective against the unbalance and the self-excited vibration. It is found that, when the acceleration of the rotor surpasses a certain value, the effect of decreasing its maximum amplitude near the critical speed is reduced rapidly.

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In the present paper, an analytical method is presented for predicting the nonlinear transient response of an aircraft engine due to the loss of a fan blade. The casing of an aircraft engine and rotors are modeled as Timoshenko beams and analyzed using the incremental transfer matrix method with the Newmark-β or Wilson-θ method. The local deflection effect of a casing cross section and the support stiffnesses are examined by FEM and are taken into account in the model. Nonliner elements are considered for contact and rubbing of the fan with casing and squeeze film dampers. Although some numerical problems still remain when very short time steps are chosen for the time integration, the present calculation method is fairly efficient and useful.

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Fluid forces reacting to structures, which are usually modeled as added mass, should be taken into consideration in response analyses of structures immersed in liquid. In this study, added masses for a predominant mode in base excitation of multiple-hexagonal-bar systems were investigated. Shaking table experiments were conducted with models consisting of up to 127 hexagonal bars, which have relatively small aspect ratios. The results showed that the actual added masses for the predominant mode are smaller than those determined by conventional analyses with the assumption of a two-dimensional fluid region because of axial pressure distribution. A formula was proposed to evaluate the added mass with the three-dimensional effect, using a simplified analysis model. Another formula was also proposed to calculate the participation factor. Both formulas were verified by making a comparison between analytical and experimental results.

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Some cholesteric liquid crystals which change their color according to temperature are used to show temperature distribution on a heat conductive surface qualitatively. This study shows a regressive expression, which includes the effects of temperature gradient and measuring angle, for the calibration of the intensity of liquid crystal. Estimated temperatures can be linearly compensated by the temperature gradient of the calibrated plate, to within 0.2°C. The absolute value of the difference between the estimated and real temperature increased with the measuring angle.

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It is necessary to separate the components of error motions of a measuring system in order to measure the surface profile of a spherical mirror on a machine. Thus, a new optical system has been developed using two quadrant photocells to measure the displacement and the inclination angle of the reflection surface at the same time. Namely, the displacement was measured by applying the principle of triangulation and the angle was detected by applying the principle of optical levers. The surface profile was obtained through the integration of the angle, and the error motion was derived by subtracting the profile from the displacement. The results showed high repeatabiliy and high reliability in comparison with the measured data using other optical methods.

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This paper proposes a new multiviewpoint stereo measurement method. Accuracy is improved by integrating stereo data obtained from multiviewpoints whose relative positions are known. In this method, a normal distribution is assumed for the measurement error on the stereo image planes. First, th probability density functions of the measurement error from the multiviewpoints are combined. Then, the combined function is expressed using real space coordinates and coordinate transformation parameters which give relative viewpoint positions, and the most likely coordinates are estimated from the condition that minimizes the function. The variance in the estimated coordinates is analyzed. As a result, the optimum viewpoint positions for minimizing the measurement error are investigated, and the relationship between the number of viewpoints and variance of the optimum viewpoint positions are calculated. Finally, these results are confirmed by computer simulation.

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In the present report, dust collection performance in a cross-current-type moving bed dust collector is experimentally investigated, and the optimal control of the dust collector is discussed. First, a model of the dust collector is discussed to simulate such aspects of dust collection performance as collection efficiency and pressure drop. The model of the dust collector is expressed as an aggregate of blocks with a unit volume, and simulations of collection performance are carried out using the model. Next, the optimal control of the moving bed dust collector is discussed. In the control of the dust collector, it is impossible to set the set-point of the pressure drop and the collection efficiency independently from the viewpoint of the characteristics of the dust collector. Hence we propose a fuzzy optimal control method as a control algorithm. By giving the value of weight in the performance function, a dust collector that meets the application can be constructed.

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Stability and self-excited vibrations in a hydraulic servo system affected by Coulomb friction have been studied by digital simulation and a piecewise linear method. The neutral operating point of the servo is always stable for any supply pressure. The system has a multiple structure of stability, which consists of unstable and stable limit cycles around the stable operating point. Thus self-excited vibrations can occur only for disturbances beyond a certain critical value. The self-excited vibrations of small amplitude correspond to stick-slip vibrations different from the usual type.

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Fuzzy control has been applied to many kinds of real industrial processes. In the design of complex systems such as multi-input/multi-output systems and nonlinear systems, it is difficult to acquire expert control knowledge and to determine optimal parameters of membership functions. This paper presents a simplified design method for fuzzy servo systems for nonlinear plants. The features of this method are as follows. (1) This method consists of a simple design procedure. (2) This method guarantees stability of fuzzy servo systems. (3) This method results in the rejection of steady-state error and disturbance. Finally, the effectiveness of this design method is verified by a simulation experiment of control of the water level of a multi tank system.

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A thermal off-track compensation system for a dedicated-servo-type magnetic disk drive with a piezoelectric fine head positioning mechanism has been developed. It measures the amount of the off-track displacement of each head at the reference cylinder whose tracks on data surfaces have position information. If the off-track displacement exceeds the limit, it is compensated by displacement of the piezoelectric fine head positioning mechanism. The piezoelectric actuator is driven along a predetermined voltage trajectory with regard to its calibration curve in order to be free from the hysteresis effect. Heat-run tests show that the system effectively suppresses the thermal off-track displacement.

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The purpose of this study is to improve the control performance of radial piston type and vane type pneumatic motors and to investigate whether they can be used in a high-accuracy control system. In this paper, we consider the stabilizing and swinging up control system of a double-inverted pendulum as a high-accuracy control system. Firstly, some basic characteristics of the pneumatic drive, consisting of a pneumatic motor and a control valve, were investigated. Secondly, digital controllers for stabilizing and swinging up were designed taking into consideration the time lag of the pneumatic driving part. As a result, these controllers could stabilize a double-inverted pendulum and could swing up and stabilize a single-inverted pendulum well, with both types of pneumatic motor.

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A theoretical and experimental study is presented for the force control of a miniature gripper driven by piezoelectric bimorph cells. One finger of the gripper is modeled by a flexible cantilever with a force sensor attached to its free end. A pair of piezoelectric bimorph cells are glued to both sides of the cantilever. The mate of the finger is assumed to have adequate stiffness and can be modeled by a rigid beam. In the analysis, the output of the force sensor is defined by the arm tip displacement multiplied by the sensor stiffness. Both the PID control and the digital optimal control scheme are introduced to drive the arm so that the tip produces 0.03 N and maintains the commanded value constantly. It is shown that both the experimental and theoretical results are in good agreement with each other, further the piezoelectric bimorph cells work well as an actuator in minute force control of the gripper.

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A learning fuzzy controller is described for controlling a robot manipulator. The learning controller used here is called a multiple fuzzy controller, in which several elemental fuzzy controllers are processed in parallel and the degree of usage of each inferred consequent is determined by using a linear neural network. Two learning algorithms are considered in the framework of the specialized learning architecture : one is based on minimizing the squared sum of the trajectory error for each link and the other is based on directly minimizing the trajectory squared error for each link. The effectiveness of the proposed controller is illustrated by making some simulations for a two-link manipulator.

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The SCARA robot control system, which comprises environment monitoring, collision-free path planning, joint trajectory generation and trajectory control, is developed. In environment monitoring, the work space is displayed on a CRT through a TV camera and obstacles are then interactively modeled. The collision-free path is planned based on the configuration space method, and the shortest path is heuristically obtained. The path is described by a set of joint trajectories using the B-spline curve. The trajectories are iteratively improved to optimize the specified performance index considering the robot dynamics. The generated trajectories are used as reference joint trajectories to control the robot. Control parameters are also determined according to the identification of the robot. This system is confirmed to be effective throughout experiments.

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This paper deals with the problem of controlling the brachiation robot (BMR), which moves dynamically from branch to branch like a gibbon swinging its body in a pendulum fashion. In the previous reports, we proposed a control method for BMR, which consists of heuristic learning to generate feedforward driving torques and the trajectory and arm-direction feedback control, and confirmed that the proposed method can achieve locomotion of the 2-link BMR in simulations. In this paper, an experimental model of the 2-link BMR is presented and some experiments are carried out using it to realize its locomotion. A method to control the oscillation amplitude of the BMR will also be addressed, and some motions such as catching a branch from a pendant state and recovering from a miss locomotion are realized.

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This paper describes the concept of making a microrobot with an external skeleton, like an insect, and its implementation using rigid plates and elastic joints. A large-scale model consisting of plastic plates and solenoids is shown to demonstrate the motion of the external skeleton system. Moreover, several microsized models using polysilicon plates and polyimide joints have been built on silicon wafers. By folding the mechanisms at the joints, just like paper, three-dimensional structures can be constructed. These structures can be actuated by electrostatic force.

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The frictional traction behavior of elastohydrodynamic contacts under pure sliding reciprocation with and without cycli impact loading is studied using an optical interferometry device. In the full elastohydrodynamic lubrication regime, the traction under simple reciprocation is almost constant in a wide range of sliding velocity and the value can be estimated from that under unidirectional conditions. It is also found that the thick oil film entrapped between the contacting surfaces by impact loading can reduce the traction. The reduction ratio of the traction depends on the frequency of the impact loading and the length of the reciprocation.

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A new concept of "friction-assisted extrusion" to produce a thin metal strip is proposed. In the process, a rectangular prismatic workpiece inserted into the container is compressed by a punch against an anvil, and the anvil is forced to move horizontally. A thin strip can be extruded through the gap by the high friction force over the anvil surface. Very thin strips of aluminium and copper up to about 50 μm in thickness could be formed up to the extrusion ratio R = 200 with a considerably low punch pressure ratio p/2k=1∼2(p : punch pressure, k : yield shear stress), which agreed with the theoretical value estimated by the upper bound method.

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The friction-assisted extrusion of thin strips developed by the authors was applied to a powder-forming from pure aluminium powder. The thin strips of 0.05-2mm in thickness could be cold-formed directly from the aluminium powder with a considerably low punch pressure ratio p/2k=0.9-1.2 (P : punch pressure, k : yield shear stress), which agreed with the theoretical value estimated by an upper bound method. The thin strips formed from the aluminium powder have superior mechanical properties to the strips formed from aluminium blocks, such as Vickers hardness HV = 60-90, ultimate tensile strength S_T = 220-320 MPa, total elongation e_T = 4-5% and so on.

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Novel micropumps have been designed and fabricated. Mercury drops driven by an electromagnetic force sweep the fluid into a pipe. The advantage of these micropumps are their simple structures and lack of moving solid parts. There are two kinds of micropumps, namely, the rotary type and the reciprocating type. Their overall dimensions are 10 mm and 25 mm, respectively. Both types functioned successfull as pumps, and their performance was evaluated using parameters derived from basic experiments. The maximum flow rate, the maximum pressure and the maximum power are 3.4ml min^-1, 0.67 kPa and 9.7 μW, respectively for the rotary type, and 0.32 ml min^-1, 0.34 kPa and 1.3μW for the reciprocating type. It has been demonstrated that a restoring force caused by surface tension can be errectively used in the microscale. This paper presents a method of calculating the restoring force based on appropriate assumptions.

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It is difficult to employ the torsion bar spring as an actuator in operating mechanisms because of its great length, even though it has advantageous characteristics. A new spring element with easy application is needed to be developed to obtain a compact mechanism while retaining the advantages of the torsion bar spring. The new spring, known as a parallel bar spring, is constructed with two torsion bar springs in parallel to reduce the length. This paper shows the practical calculation methods for the characteristics, stress and limit of torsional deflection of the parallel bar spring, and the results of analysis are confirmed by the test results of the application example on the spring operating mechanism of the SF₆ circuit breaker. The spring acts as a straight torsion bar spring in series, and the bending stress is negligible.

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The characteristics of a bolted joint, in which the cover of the pressure vessels made of aluminum was fastened at room temperature by bolts and nuts made of steel, were examined when the joint was subjected to heat conduction. With the use of the finite difference method, the temperature distributions in the joint subjected to heat conduction were analyzed. A method for obtaining the increment in bolt axial force and the maximum stress produced in the bolt was proposed. In the experiments, temperature distributions on the joint were measured with thermocouples, and the increment in bolt axial force, the maximum stress in the bolt and stress produced at the hub of the flange due to the difference in the coefficients of linear expansion were measured by strain gauges for high-temperature use when the inner circumference of the pressure vessel was heated (cooled) and the outer circumference was kept at room temperature. The analytical results were fairly consistent with the experimerltal results.

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A few tests were carried out to determine the strength and rigidity of reinforced concrete for foundations, the performance element of the exposed fixed column base made of a cast steel base plate, and the strength and rigidity of anchor bolts initially prestressed without constraining the shank. Stress was introduced to the reinforced concrete using a distribution plate, and its bearing strength was evaluated using the bearing surface area and the distance between the bearing-surface and reinforced concrete ends as parameters. Initial prestress was introduced into anchor bolts embedded in the reinforced foundation concrete, then a pull-out load was applied, and the elasto-plastic behavior of the bolts was clarified.

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This paper describes the manufacture of injection molding plastic magnetic bearings. The polarity of the inside ring face is different from that of the outside ring face in one bearing. Those bearings rotate without contact bearings. If such bearings can be of practical use, the noncontact bearings should be in clean room and space environments where lubricating oils can not be used. This first paper was written primarily discuss the principle of plastic magnetic bearings regarding the injection mold method of magnetization and measurement of flux density. It was possible to put the injection molding plastic magnetic bearings to practical use in this experiment.

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Recently, for the purpose of enhancing mechanical performance utilizing the functions of plastics, many kinds of super engineering plastics have been developed. Their fundamental characteristics have been reported, but the data are insufficient for carrying out design based on them. In particular, there are hardly any data which can be used for the design of gears. For this reason, in this research, gears were made of several kinds of super engineering plastics which seemed capable of being put to practical use, and their various characteristics, such as the load-carrying capability and the wear of the teeth, were elucidated. In this report, among the results of these operation tests, first, those for polyimide gears are reported.

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This paper presents a study on root stresses of thin-rimmed internal spur gears supported with press-fitted pins used for a planetary gear unit. Stress analyses by the two-dimensional finite element method (FEM) for thin-rimmed internal spur gears supported with press-fitted pins were carried out. The effects of the interference between pin and hole for pin, the circumferential and radial positions of pin and the pin diameter on the root stress and the stress at the press-fitted surface of the hole produced by press-fitting pins were determined. The root stress and the stress at the press-fitted surface produced by applying tooth load after press-fitting pins were examined, considering the friction between contacting surfaces.

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The number of teeth in contact and the loading capacity of gear-type shaft coupling having pitch errors are calculated based on statistical theory and are compared with the results of numerical simulations. The probability distributions of the pitch error and the allowable load of the material of gear-type shaft coupling are presumed to follow a Gaussian distribution. The simulation is carried out using Gaussian random numbers for the pitch errors and the allowable load. The theoretical calculation agrees well with the results of the numerical simulations.

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The frequency equations of straight bevel gears were derived, and then the fillet stress and the displacements of three directions perpendicularly intersecting each other in a bevel gear were calculated on the computer. Furthermore, the calculated results obtained were compared with the experimental results. The conclusions are as follows. The calculated results approximately agree with the experimental ones. The fillet stress ratio markedly increases under the effect of natural frequency in torsional vibration of bevel gears. The natural frequency in the torsional vibration of the gearing system and in the bending vibration of the gear shaft has a considerable influence on the displacements of the bevel gear in three directions.

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To elucidate the effect of hardened depth on the fatigue strength of carbonitrided gears, gears with three kinds of hardened depths were fatigue-tested using a power circulating gear testing machine. In the case of gears with the shallowest and intermediate hardened depths, the failure mode was spalling. In the case of the gear with the deepest hardened depth, the failure modes were spalling and tooth breakage due to bending at the tooth fillet. The surface durability was higher with deeper hardened depth. The strength for bending strength of gear with the deepest hardened depth was lower than that of a gear with intermediate hardened depth under the same loading condition. Therefore, when carbonitrided gears are designed, it is important to decide the optimum hardened depth of those gears. The change in dynamic performance of every gear was slight during the fatigue processes, since the change of tooth profile of every gear was slight.

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The purpose of this study is to investigate the fatigue strength of carburized gear steel chemically vapor deposited with titanium carbide, and to clarify the main effect of carburized gear steel coated with titanium carbide on fatigue strength, including comparison with noncoated steel. Case depth of carburized gear d_eff is 1.3 mm. Quenching and tempering heat treatment after coating was also introduced. Smooth specimen, that is, flat plates and spur gear, module 4 with number of teeth 55, were supplied to fatigue test. Residual stress in TiC surface layer and substrate was detected by X-ray diffraction method. It is concluded that main effect on fatigue strength of chemically coated steel on carburized steel is substrate hardness near surface layer, and residual stress in titanium carbide layer doesn't effect prominently on fatigue strength. And finally it is found that the residual stress in both TiC layer and substrate near interface indicates possibility of a micro crack initiation at the interface between titanium carbide and substrate.

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The entrance angle of hob teeth greatly depends on hob design, gear design and cutting conditions. This exerts serious influence upon damage to the hob. If the entrance angle is small, the cutting edge slips easily at he beginning of cutting, and damage (chipping and flank wear) is increased. Therefore, it is important to grasp how the entrance angle changes, in the case of hob design and selection of hobbing conditions. The authors report the value of an entrance angle that depends on module, hob diamerter, number of flutes, number of threads, number of gear teeth, helix angle and hobbing method clarified by calculation.

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During the machining of brittle materials, the brittle-ductile transition (B-D-T) is related to the machining conditions. In this paper, micro-cutting is carried out to investigate the effect of B-D-T on the surface integrity of silicon single crystals. Surface texture, residual stress and crystal properties of the machined surface are evaluated with a surface roughness tester, scanning electron microscopy, atomic force microscopy and micro-Raman spectroscope. Results are as follows : (1) For the ductile mode cutting surface, the surface roughness of 0.005 μm Ra, compressive residual stress of 23.0 MPa, surface topography and crystal properties are nearly the same as that of the polishing surface. (2) For the brittle mode cutting surface, the value of the surface roughness Ra is much larger than that of the polishing surface, as is the compressive residual stress at the value of 172.5 MPa. (3) The value of the critical material removal rate, ΔV_c, for ductile mode cutting, as well as the critical depth of cut, becomes smaller with the increase of feedrate.

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Spheres are used in various rotational machine elements because they have infinite degrees of freedom for their movement. Typical examples of such elements are bearings, masterballs, gyrortors and so on. However, at the finishing stage of their lapped process, it is quite difficult to control their rotational movement, although the spheres should be rotated in all directions in order to achieve higher accuracy in the roundness. In this paper, a 2-cup-type lapping machine was examined and the factors which affect the roundness were extracted by the techniques of experimental design. As a result, it was found that the behavior of the rotation vector of the sphere in the lapping process is one of the most important factors for the formation of higher roundness.

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The floating phenomena of the tape on the rotating drum in VCRs were treated as an air-bearing problem using the averaged thickness theory coupled with a tape deformation problem of an anisotropic thin shell equation in FEM (Finite Element Method). We obtained the floating height distribution dependence on the groove structure of the drum by computational simulation. We compared the averaged thickness model and the exact node model. We showed that the square grooves are more effective than the triangular grooves. Good agreement between the calculated and the measured results on the tape floating behaviour has been obtained. We showed the effectiveness of the structure/fluid coupled analysis using the averaged thickness theory. The computational simulation is very useful for designing the new VCR systems and determining the effects of design parameters.

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One of the strategies for achieving continuous growth in firms is the diversification of products. In diversification, manufacturing resources for a product whose market is matured are moved to the manufacturing of a product whose market is growing. The diversification has risks in that the firm may fail to get a return, because competition in a growing market is fierce. In this research, a production planning problem for a firm was analyzed to maximize the expected return and to minimize the risk on the return. An optimization method was developed to determine production quantity and allocation of production capacity, and a numerical example was demonstrated.

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