The non-Gaussian response distribution of a single degree-of-freedom system with nonsymmetric nonlinearities subjected to nonwhite random excitation with nonrational spectra is investigated. The nonstationary and stationary probability densities of stochastic responses are calculated by employing the method which consists of the non-Gaussian equivalent linearization technique and the use of the moment equations approach. The non-Gaussian probability density function for the response distribution is expressed in terms of the potential of the system and employed for determining the equivalent linear coefficients. The results are compared with the corresponding digital simulation results.

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Hybrid experimental method, in which an actuator-excited vibration experiment and a response analysis with a computer are on-line combined and simultaneously conducted, is being developed as a new seismic experimental method for structural systems. We developed an experimental system which can conduct hybrid experiments in real time by introducing actuator-delay compensation. By using this system, the dynamic characteristics of the structure under experiment become possible to be properly considered in the response calculation. In order to demonstrate that the system can be used for sesimic experiments of nonlinear structural systems, real-time hybrid experiments of single-degree-freedom systems including a few types of nonlinear characteristics were conducted and the experimental resulsts were compared with the analytical results obtained from numerical time-integration. Even though small discrepancies caused by compensation error were observed, the experimental results were successfully agreed with the analytical ones.

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The oil flooded screw compressor rotates with contact between the corresponding male and female rotors. As gas pressure rises in the grooves of the rotor, a periodically fluctuating torque occurs. An impact vibration between the male and female rotors is induced by the torque. In this report, impact vibration analysis is carried out considering movement of both rotors. The stable region of the periodical impact vibration, which causes a noise of compressor, is calculated. Except this region, the impact damped vibration only occurs, where the compressor is driven quietly.

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Experimental results are presented on chaotic oscillations of a reinforced beam subjected to lateral excitations. The beam is partially reinforced with boxed-type stringers. The beam is clamped at both ends on a base frame. One end of the beam is arranged to move to an axial displacement by attachment to an elastic spring. The beam is deformed to a post-buckled configuration by the axial constraint. Under the post-buckled condition of the beam, chaotic responses are generated in specified regions of exciting frequency. A response is expected from a system with a lower degree of freedom. The chaotic responses are analyzed by the Fourier spectrum, the Poincare section and the maximum Lyapunov exponent. It is found that the chaos of the beam is generated with the fundamental mode of vibration. Chaotic response includes the resonance modes both of a higher lateral vibration and of an axial vibration. The Poincare projections of the chaos show clearly the stretching-and-folding mechanism of the chaos attractor. The instability boundary of the chaos is obtained in the plane of exciting frequency and amplitudes of excitation.

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Dynamic behavior of smooth hysteretic systems subjected to harmonic excitation is analyzed and the regions of non-symmetric solutions are obtained. Using the piecewise power series expression for hysteretic restoring force, the variational equation based on symmetric approximate solution is derived. Floquet's theory and method of harmonic balance are applied to the variational equation in order to determine the stability limit, outside which even order harmonics grow. Obtained regions in parameter space are compared with numerical simulation results by shooting method in order to examine the validity of the present analysis.

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A new method for getting periodic solutions for Piecewise Linear Oscillator is proposed. From the steady state responses, periodic solution for the oscillators can be derived by using pseudo feedback approach. It is shown that for some piecewise linear systems, periodic solution can be globaly represented by the form of superposition of steady response of linear system and periodic pseudo feedback responses. By comparing the results through the method with those of numerical simulations, the validity of the proposed method is confirmed.

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This paper deals with a method for analysis of the in-plane vibrations of plates. The in plane vibration is described as a plane stress problem with inertia forces. The governing equation can be reduced into two Helmholtz's equations which express the P- and S-waves respectively. The general solutions in the polar coordinates of the reduced equations can be obtained easily in terms of the Bessel functions. Boundary conditions are satisfied approximately at some discrete points on the edges of the plates. A frequency equation is derived in a determinant form. Natural frequencies of a square, a rectangular and a trapezoidal plate, with free edges, calculated by this method agree well with measured ones. Furthermore, boundary conditions of clamped edges and sliding edges are studied.

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This paper describes the resonant response of the compound periodic structures which include both grouped and one-ringed blade structures in a turbine wheel to form a circumferential periodicity with a packet as a unit. By calculating the energy supplied from engine order excitation to a natural mode composed of plural nodal diameter modes, the resonant conditions are derived. Then, the resonant stresses are calculated by equating the energy supplied and the energy dissipated by damping. The resonant response and stresses are exemplified for a simple blade model with an assumption of fixed or traveling mode around the periphery.

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In recent years, highly developed vibration control techniques have been in demand for suppression of vibration responses of various structures which are subjected to seismic and wind excitation to achieve high performance and design accurancy. In this report, we aimed to develop a multifunctional vibration control device proposed earlier, referred to as a mechatro damper, and to apply it to a seismic isolation system. This paper is focused on the active control methodology based upon linear control as well as sliding mode control. The results obtained through numerical simulation and dynamic testing for the active mode are presented and compared with those for the semi-active mode obtained in the former report.

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This report deals with the experimental and analytical study of seismic response behavior of piping systems in industrial facilities. Piping is generally set up on the supporting structures, therefore when shaking motion is given, frictional vibration should take place between the piping and the supports, and two dimensional sliding motion occurs. A three dimensional mock-up piping and supporting structure model is excited by large scale (15m×15m) shaking table. First mode and second mode of FEM piping model are calculated independently, and maximum responses and dissipated energy considering the frictional behavior are compared with the responses obtained by experiment. The process to calculate the response of friction system is evaluated.

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This paper proposes a hybrid-type vibration isolation system controlled by a frequency shaped weighting function and a phase compensated LQ control method. The hybrid system is composed of a passive spring-damper system reducing vibrations of high frequency area and an active one reducing those of low frequency area. This system is controlled by the phase compensated digital LQ optimization method with a frequency shaped weighting function. By the proposed method, the phase lag of the control system is compensated so that the vibration isolation performance is improved. Simulations for the active system are carried out and the effectiveness of the phase compensation is shown. Then, experiments for the hybrid system are carried out for sinusoidal or random excitations. It is confirmed that the purposed hybrid system has the excellent isolation performance for excited vibrations over the wide frequency area.

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The nonlinear coupled vibrations in an elastic structure and liquid sloshing in a rectangular tank are investigated. The tank has a free surface and the structure supporting it is vertically subjected to a sinusoidal excitation. In the theoretical analysis, the resonance curves for the responses of the structure and liquid surface are presented by the approximate method, when the natural frequency of the structure is equal to twice the natural frequency of one of the sloshing modes. From the theoretical analysis, we have obtained the following results: (a) Due to the nonlinearity of the fluid force, harmonic oscillations appear in the structure, while subharmonic oscillations occur on the liquid surface, (b) the shapes of the resonance curves change markedly depending on the liquid depth, and (c) the resonance curves for an arbitrary excited sloshing mode can be easily obtained by merely changing the dimensions of the tank such as the length and the width in the theoretical equations for the first sloshing mode. These results were qualitatively in good agreement with the experimental results obtained from having used water as the liquid.

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A new type of high-damping rubber damper for vibration control of tall buildings has been being developed in this study. This paper describes the temperature dependency of the damper which will be an important problem in vibration control systems using high molecule material. The tests were carried out in two different conditions from the viewpoint of the temperature variation of vibration control material into the dampers. One is the variation of environmental temperature around the damper and the other is the self-generated heat in the damper which will be induced by the cyclic loading such as earthquake or wind. Moreover, the durability of damper was investigated by following tests; breaking test, static tests and cyclic loading tests under excessive shear strain amplitude. As the results, it was confirmed that the temperature dependency of the damper would not much affect to the energy absorbing characteristics even in the case of the practical use and the durability of the damper was highly enough against the large earthquakes by means of its strong adhesive characteristics.

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Many vibration control systems, which are divided into a mass damper system and a storey-installation damper system, for habitability or seismic-safety improvement in high-rise buildings have been developing in recent years. However, a passive energy absorbing system will be the most ideal devices if we consider to reduce the structural responses against the various levels of inputs such from traffic induced vibration to destructive vibration. This study has been developed the vibration control system of an energy absorbing type used the high-damping rubber as a vibration control material. We had already cleared experimentally and analytically that the high-damping rubber damper has stable damping performances in wide vibration area through the various loading tests and the shaking table tests. In this paper, the fundamental performances and the vibration control effects of the full size high-damping rubber damper which was made from the results up to this time is described.

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Large size turbine generator inside is cooled by hydrogen gas. The casing of generator provides a hydrogentight enclousure and seal rings are located at both end of the casing, in order to seal between the rotor and the stationary parts. In the case of bad sliding condition of seal ring, the shaft vibration of generator rotor is increased due to the rubbing phenomina between seal ring and rotor shaft. Using test and analysis, the characteristics of the seal ring rubbing phenomina are obtained. The test are conducted using the full size model. The test result shows good agreement with the analytical result. The discriminating and preventive method of this phenomena are discussed.

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This paper presents the dynamic analysis of curving behavior of railway vehicles. Curving simulation of vehicles running at low speed is important from a point of view of safety. But it haven't often been done and results of simulation usually different from measured them. Though the influence of leveling valves and differential pressure valves can be generally ignored in the case of simulation of vehicles running at high speed, the effects of them must be considered at low speed. Therefore we irproved A'GEM which is multibody dynamics software to add non linear air suspension with leveling valves and differential pressure valves. The results of curving of simulation were compared with experiments with good agreement.

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The speed-up on railway tends to require higher powered and heavier locomotives, thus two three-axle trucks or three two-axle ones are needed for the heavy locomotive to meet the limitation to axle load. Here, it is beneficial for heavy locomotives to employ forced steering trucks to reduce the lateral force between the wheel and rail during curve negotiation. This paper deals with numerical analysis about curving behaivor and running stability of the forced steering three-axle trucks. In the analysis, wheel lateral forces and the critical speed for stable running are examined parametrically varying leverage ratio and stiffness in the steering link, wheel tread conicity and wheelset supporting stiffness. In addition, the possibility for improving the critical speed is investigated. The results show that the proper value for the leverage ratio changes with curve radius, and that higher leverage ratio can make the running stability worse under large steering link stiffness. It is also shown that the proper tuning of the wheelset supporting stiffness increases the critical speed keeping the lower lateral force brought by the forced steering mechanism.

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In recent years, active suspensions have been studied for improving the ride quality of railway vehicles. In the active vibration control, it is important that the control system be robust against mass variation of the car body due to the varying number of passengers. However, it was indicated that LQG controller can become unstable when the body mass is lightened. Although H_∞ controller is stable against the mass variation, it is expected that the adoption of μ synthesis can improve the control performance still more. In this paper, the car body mass variation is considered in the linear state space representation of control object as parametric uncertainty, so that the μ synthesis can be adopted for the controller design. The control performance of the μ controller is investigated with a 3 d. o. f. half-vehicle model experimentally. As a result, it is shown that the μ controller improves the deterioration due to the car body mass reduction, and that it provides better control performance using a frequency dependent weighting function more than using constant weightings for the uncertainty of the mass variation.

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Vibration of hydraulic piston pumps has raised acute noise problems. In this work, a tandem piston pump with a swash plate is considered as a many-body combination system which has seven mass and thirty-five degrees of freedom. Motion equations expressing the entire system are used for analysis of the dynamic response of the system. Numerical analyses are performed by the Newmark-β method for discrete application of difference approximation to a matrix consisting of those equations with respect to incremental time. Satisfactory agreement between calculated and experimental responses is obtained. Then the influence of a change in the pressure pulsation phase of the tandem pump on response is clarified. By response analyses regarding pump casings by the finite element method, the influence of increased casing rigidity on response is also evaluated. It is confirmed that both the coincidence of the phase in a tandem piston pump and increased casing rigidity are effective for reducing vibration of the pump.

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Flow simulations of spherical and nonspherical particles were conducted by Cellular Automata method. Cellular Automata method is a class of mathematical systems characterized by discreteness, determinism and local interaction, which was proposed by J. von Neuman and S. Ulam. It is recognized as one of the effective methods to simulate various emergent behavior such as particle flow, biological pattern formation, chemical reaction-diffusion problems, economic growth, etc. In the present paper, several local rules proposed by Baxter et al. and the authors based on physical consideration were used in the simulation of particle flow. The filling process of particles in a hopper, the flow pattern in a hopper and the accumulation behavior on a fiat floor were simulated by Cellular Automata method. An experiment was also conducted using spherical and nonspherical particles, and the simulated results show good agreement with the present experimental results.

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This paper deals with the static characteristics of a torque motor used in servovalves. The torque motor consists of permanent magnets, pole pieces, coils, an armature, a flapper and a flexure tube. Analytical study on magnetic circuit and elastic structure are performed, and equations are obtained to describe relationships between electric current and (a) magnetic moment acing on the armature; (b) flapper displacement. The static stability criterion of the system is given in a nondimensional form. Although the magnetic flux leakage and the reluctance of the permanent magnet decrease the torque gain of electric current, they reduce partly the nonlinear character of the system such as change of local spring constant. The static stability of the torque motor system can be established by giving sufficient rigidity to the elastic components.

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This paper presents a study on the linear compensation of nonlinear hysteretic piezoelectric ceramic actuators. Both the feedback control using the strain guage output and the self-sensing control technique are investigated. In the strain feedback control, the strain on the surface of the actuator is measured directly by using the strain gauge and the output is fed back to the input voltage to decrease the actuator hysteresis. In the self-sensing control, the voltage generated by the piezoelectric effect of the actuator is detected by a bridge circuit and then used as a feedback signal to compensate for the nonlinearity of the actuator. The experimental results show that the self-sensing feedback control is more efficient to reduce the hysteresis of the actuator. Further, the self-sensing compensator is more simple and needs no additional external sensing devices.

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This paper deals with a digital adaptive control method for a manipulator mounted on a space robot after it captures an unknown object. Most of the previous control methods are based on the supposition that all physical parameters of the space robot system are known. However, if the end-effector catches an unknown object, the physical parameters of the robot are changed, and the control performance deteriorates. In this work, we propose two types of digital adaptive control algorithm in which a discretized kinematic equation is used. One is for discrete time Resolved Motion Rate Control (RMRC) with adaptive control and state feedback, and the other is for discrete time RMRC using a simplified Generalized Jacobian Matrix (GJM) with adaptive control and state feedback. Experimental results show that the control performance can be enhanced by use of the two proposed methods, and we conclude that simplifying a GJM is valid for the adaptive control system proposed in this paper.

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Active control of maneuverability and stability of a vehicle on uneven roadways by attitude control with active suspension is studied in this paper. It is well know that the stability against external disturbance due to uneven road surface is one of the most important items regarding maneuverability and stability. A half car model with active suspension is, in this report, used for pitching and bouncing motions, and a two-wheeler model of front steering type is provided for lateral and yawing motions. The influence of pitching motion of vehicle body on stability is obtained by these models. After that, the effects of attitude control of active suspensions with optimal controller on vehicle stability are clarified, for cornering maneuver on uneven road surface.

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This paper deals with the design problem of adaptive model output following controllers for MIMO plants with unknown orders. A design scheme for an adaptive control system based on the CGT theorem, which has hierarchical structures derived by backstepping strategies, is proposed for MIMO plants with unknown orders but with known relative MacMillan degrees which correspond to relative degrees for SISO plants. The boundedness of all the signals in the resulting control system and the stability of the control system are also discussed.

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We have studied disturbance observer and applied its control method to the 6-DOF manipulator which is driven by hydraulic power and also confirmed that disturbance estimation & compensation control is robust in the sense of 'model-matching characteristic' to the output of the nominal model. On the other hand, the disturbance canceling controller has the same configuration as a model matching 2-DOF control system, in which Q(s), that is a stabilizing filter, plays a very important roll against robust stability of control system. In this paper we propose new design method for the Q(s) by applying H-Infinity control theory and as a result, it was verified by an experiment in which robust, stable positional precision can always be achieved against fluctuations in the system parameter.

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This paper discusses the repetitive control problem for a single-input, single-output linear digital system. The servo problem with periodic references signal and periodic disturbances is transformed into a regulator problem by using the deviation system of the augmented system. Then, the fixed-endpoint approach is applied, and the optimal control is obtained. Furthermore, the sub-optimal control which is more simple and practical than the optimal control is proposed. In both controls, the output follows the periodic reference signal without error within finite steps.

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We describe how to build three-dimensional deployable truss structures from the viewpoint of deployment reliability. We propose a method for designing a closed-loop deployable truss structure for a future large space antenna by using a kinematic degree-of-freedom analysis of the mechanical system. Using this method, it is possible to attain a truss structure with the appropriate constraints. We have designed and fabricated a prototype of the proposed antenna truss structure, and have achieved successful deployment under the microgravity environment yielded by the parabolic flight trajectory of an aircraft. Thus we have demonstrated the effectiveness of the deployable truss structure design using the kinematic degree-of-freedom analysis.

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The simultaneous optimum design of structural and H^∞ control system is a complex and multiobjective optimization problem. It is very important to select an appropriate objective function in order to obtain a superior design. In this paper, an objective functions is proposed in the case of simultaneous optimum design to derive a better design than in the case of individual optimum design. In this method, every objective function is normalized in order to unify the available range of each objective function. Using this method, all objective functions, which are related to the structural and control objective functions, can be estimated equally. In the numerical example, simultaneous and individual optimum design have been carried out. It is shown that a better design can be obtained using the proposed objective function in the case of simultaneous optimum design than in the case of individual optimum design.

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In automotive body design it is possible that better performance can be obtained with a flexible structure rather than the stiffest structure. However, if only the flexibility is considered, the total performance of the structure may decline since flexibility may lower the stiffness and the eigen-frequency. To overcome this problem, a multi-criteria design method must be developed. In this paper, a methodology to obtain an optimum design considering flexibility, stiffness, and eigen-frequency is presented. First, the flexibility, the stiffness, and the eigen-frequency and their sensitivities are formulated using variational calculus, and a new multi-objective function is constructed. This multi objective function considers the maximum of the three criteria and is also extended to the multi-flexibility case. Next, the optimization problem is solved using the homogenization method and sequential linear programming (SLP). Finally, several design examples are provided to confirm that the proposed design method satisfies the problem specifications.

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Cross-flow fans often generate rotational noise called blade passing tones. An effective way to reduce noise is to design the shape of the blades so that the interference between the pressure fields of the noise sources eliminate the blade passing tones. The use of the fans whose blades are not straight in the axial direction is therefore increasing. However, the noise reduction effects of fans with such shapes have not been evaluated sufficiently as yet because a proper estimation method has not yet been developed. In this paper, a method for modeling the fan noise is proposed. In this method, the noise sources are approximated as point sources along a line, and an equation for the total acoustic power of the sources is derived. The power reduction effects are calculated for various fan shapes using the proposed model, and the results are discussed.

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A multilevel programming approach is proposed to optimal design of energy supply systems in consideration of their robustness in economic and energy saving characteristics against the energy demand uncertainty. Equipment capacities and utility contract demands are determined so as to minimize the annual total cost for average energy demands, to minimize the difference between the annual operational costs for the worst and average energy demands, to maximize the difference between the annual operational costs for average and the best energy demands, and to satisfy all the possible energy demands. This optimization problem is formulated as a three-level linear programming problem, and its solution is obtained by repeatedly solving a linear and a set of linear and bilevel linear programming problems which give, respectively, lower and upper bounds for the original objective function. Through a numerical case study on a cogeneration system, the effectiveness of this approach is ascertained, and the influence of consideration of the robustness on the cogeneration unit sizing is clarified.

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It is necessary to measure the flying height of a slider on an actual magnetic disk when designing magnetic disk drives. However in typidcal spacing measurement methods, the magnetic disk is usually replaced with a glass disk. In order to measure this real spacing, we developed a flying height sensor based on Frustrated Total Reflection. To measure the real flying height optically, the phase shift on reflection at magnetic disk is an important problem. In this paper we describe theoretical treatment of the problem and introduce the modified effective refractive index method and measure the effective refractive index of an actual magnetic disk. Flying height on the magnetic disk was also measured using the obtained effective refractive index. The result was compared with the flying height measurements measured by the traditional interference method. They agreed with each other with an error less than 2 nm.

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In this work, controlling a vehicle so that it does not bump into the wall of corridors in buildings is taken up as a problem of visual feedback control. The purpose of this study is to carry out such control using visual information in the real world within real time. We use 1-D optical flow calculated from intensity data obtained using a CCD linear sensor, as the visual information. Then a qualitative index which indicates the proximity of the moving vehicle to the left or right wall is extracted from the optical flow. By this qualitative approach, stable processing of visual recognition is achieved without explicit calculation of the distance. This method is based on general and qualitative knowledge of the environment, therefore there are fewer restraints of environmental conditions. Additionally, because no numerical models of the environment or vehicle are used for control, there is no need to consider the effect of parameter errors which was a serious problem until now.

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This paper addresses issues of analysis and evaluation of manipulation characteristics for robot manipulators mounted on flexible base. End-effector motion of such the robot system can be divided into two parts: one is generated from the motion of the robot joint, another is resulted from the base flexural behavior. The latter, however, is always not desirable in the end-effector control, due to it appears as a trajectory tracking error. Such the tracking error has to be compensated by the joint torque of the manipulator in order to perform manipulation tasks precisely. It must be the case that the compensating is not possible when the robot takes some certain configurations, thus, clarifying the possibility and ability of such the compensating dynamically and manipulatively is strongly needed. From mapping relationships among accelerations of the joints, flexible base and end-effector, we introduce a concept of dynamic compensability of robot manipulators mounted on a flexible base. By analyzing the mapping relationships, some conditions are derived for judging dynamic compensability of the robot system. A dynamic compensability measure and dynamic compensability ellipsoid are proposed to evaluate degree of dynamic compensability. Calculation examples are carried out to illustrate utilization of the introduced concept.

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This paper presents a new obstacle avoidance method. This method considers the limitation of the motion which is decided by the mechanical restriction of the motion and the characteristics of the actuators to drive the robot. So the robot can follow the motion planed to avoid obstacles. This method can apply to each robot, because the specification of the robot is treated as parameters in the method. The area of the movable orientation of the robot is calculated according to the specification of the robot (the limitation of the motion, the range of the external sensor, the period to plan the motion, etc.). The orientation to move is common to the area of the movable orientation and the area of the orientation which can avoid obstacles. Then the robot changes the orientation, keeping the limitation of the motion. The effectiveness of this method is shown by simulation.

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Error and sensitivity in the direct dynamic simulation of the motion of a human model were analyzed using an algorithm derived from the angular momentum method. The model consisted of rigid body segments interconnected by ideal pin joints, and simulated motions of the midstance phase of human walking were performed. Several methods of numerical integration were used to determine the appropriate method and conditions for individual problems. The sensitivity of the resulting motion to the joint torque input was investigated for several kinds of simulation modes. The results showed that the errors due to numerical integration can be reduced to an acceptable level by using appropriate methods and conditions depending on individual problems. The sensitivity to torque input was more serious in some types of problems where only small perturbations cause accumulated errors in a late period. These two sources of error should be distinguished clearly and tested for using particular simulation studies of human motion.

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The purpose of this study is to investigate dynamic characteristics of the human body in a sitting position, by performing multidirectional excitation. Vibrational testing is performed using a three-axial shaking table on which a wooden seat is attached. Experiment participants sitting on the seat are subjected to excitation in three directions, i.e., fore-and-aft (x-axis), lateral (y-axis) and vertical (z-axis), in random order. The dynamics of the seated human body are characterized by transfer functions between the seat and the head. By measuring the vibration at the mouth and forehead, rotational transfer functions such as roll and pitch, as well as translational transfer functions, are obtained. In the results, two resonant peaks are observed between 0 Hz and 20 Hz in each translational direction. It is observed that the fore-and-aft motion and the vertical motion are coupled. It is experimentally confirmed that this dynamic coupling is caused by the pitch motion of the head.

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In this work, we compared the locomotive efficiencies for various creep movement curves of snake locomotion, by analyzing the power density function and the ratio of the tangential force to the mormal force. The results show that the proposed Serpentine curve (S. Ma, JSME Trans., Vol. # 62, No. # 593 (C), pp. # 230-236, 1996) is more valid as the snake creeping locomotion shape than the Clothoid and Serpenoid curves (S. Hirose, Biologically Inspired Robots, Oxford University Press, 1993).

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This paper examines human-friendly motions of a robot holding out an object to a human. The motion parameters which give humans various impressions are discussed and their human-friendly values are analyzed using the rating scale method. First, we investigated the velocity pattern of the robots'holding out motion. Experimental results show that the bell-shaped velocity pattern with velocity peak in the front of the movement time is one of human-friendly. Second, we investigated the influences of maximum velocity value. Experimental results show that appropriate values exist and appropriate values for females are smaller than males. Third, we investigated the desirable position to which the robot should hold out the object. Experimental results show that the position should be chosen so that the manipulability measure of human two-link arm becomes small.

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Magnetic resonance (MR) imaging is useful for the medical diagnosis of temporomandibular joint (TMJ) syndrome. However, the signal intensities of MR image from condyle, glenoid fossa and articular disk in TMJ are low and the difference of intensities among them is small. It is difficult to separate each structure of TMJ from their signal intensities by the computer detection system completely. In this paper, the method of separation for the closed-mouth MR image was newly developed by using the information of the image analysis of tomography and the open-mouth MR image. Three normal samples and three abnormal ones were examined practically and the method for evaluation of TMJ shape was studied. The area of TMJ space was available to distinguish an abnormal sample from a normal one. The area of articular disk and the center of gravity on it were also useful and the anterior displacement of articular disk was found in abnormal samples.

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The aim of the present study is to present improvements of mechanical seal performance for use under high-temperature and high-pressure conditions. Existing mechanical seals subjected to both high and low pressure show unstable leak rate and sliding reliability. Under high-temperature conditions, the temperature of seal face increases and thermal deformation of seal face takes place, leading to a decline in seal performance. We consider a new structure of the mechanical seal that cools the seal ring and seal face quickly, as well as the roughness and balance ratio of the seal to design. We derive the shape of the mechanical seal from experimental data. We also confirm that this seal exhibits the stable leak rate and sliding reliability under these conditions.

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ER (electro-rheological) fluids allow direct interfacing between electric signals and fluid power without the need for mechanical moving parts. This study is aimed at achieving the use of ER fluids in micromachines, in particular micro in-pipe mobile machines. In this paper, first, a three-port micro ER valve (φ9.8 mm) is fabricated, which has two pairs of electrodes connected in series. Static characteristics of the micro ER valve are examined. The valve can control a load pressure change of 0.25 MPa at an electric field strength of 5 kV/mm. Secondly, a micro in-pipe mobile machine containing the micro valves, whose diameter and length are φ9.8 mm and 34.5 mm, respectively is fabricated. The micro valves drive bellows microactuators and the in-pipe mobile machine can move in the manner of an inchworm. Performance of the in pipe mobile machine is examined. A maximum average velocity of 0.9 mm/s is obtained without load. An output power of 35μW can be achieved.

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This report describes the effects of shoes on the road in driving. Through experimental and theoretical analysis using a scale model of a crawler-type vehicle, the slip, sinkage, inclination, shearing stress and ground pressure of a shoe are obtained quantitatively and considered synthetically. The dynamic behavior of a shoe affected by roller pressure, its front and back shoes behavior and road reaction is analyzed numerically in the overall shoe contact area and in the regions under the contact points of a roller and a shoe. The main reason for shoe contrary slip, which is undesirable for the generation of crawler tractive force, is found to be a fluctuation of shoes produced by the change of rolling pressure position as a roller moves from the rear to the front side of the vehicle.

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This report studies about generation mechanism of tractive force in driving, which has not been sufficiently studied yet. The distribution and time history of tension, dynamic ground pressure, dynamic shearing stress, slip and slip ratio of a crawler belt contacting with the road are provided in details through theoretical analysis. It is demonstrated that the tractive force does not generate continuously at real time, but repeats time history of complex positive and negative pulsation. This time history of tractive force relates with the speed change of the vehicle originated by the unevenness with which track links are wound by a driving tumble. The frequency of tractive force corresponds well with that of vehicle speed change.

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Based on the 12-degree of freedom dynamic model of a helical gear system, which was constructed by putting dynamic contributions of shafts and bearings at the centers of gear bodies, a method to take gear tooth surface deviations into account as the exciting force is presented in this paper. The effect of the tooth surface form has been counted for in terms of error excitation in the plane of action where the force interacts between two mating gears through two parallel spring representing tooth-to-tooth elasticity. The method has been verified experimentally by giving shaft misalignment, or the helix slope deviation. A chart named "Amplitude Factor Contour Diagram" is also proposed which is able to suggest tolerable deviations coming from manufacturing, assembling or operating conditions.

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The process of CNC incremental forming in which a blank is formed to fit on a tool-envelope surface made by relative motion of a tool around the blank, has the advantage of not only adaptability to small-lot production of thin shell parts but also improvement of forming limit due to the effect of preventing the plastic localization. Although many cases of the effect of preventing the plastic localization on the process have been reported for one-piece blanks, the effect has not been illuminated previously for welded blanks, such as Tailored blanks. Here we report the possibility of CNC incremental stretch expanding of welded blanks so as to clarify the effect. Welded steel sheets with the same sheet thickness and grade were stretch expanded to conical shells with various half-apex angles, α, and the deformation behavior was examined experimentally. It was found that, when α is larger than abouth 35°, conical shells can be formed from the welded blanks by means of the process with a single tool-path: the forming limit of the welded blank is similar to those of the one-piece blank. Furthermore, experimental results showed that the deformation modes of the welded blank is similar to those of the one piece blank, because the strain distributions in the weld regions as well as in the unweld regions were approximately equal to those obtained from the Sine law. These results suggested that the effect of preventing the plastic localization holds for the welded blanks.

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It is well known that shape profiles can be measured by the serial three point method with three displacement sensors. This method, however, has disadvantages in that it is difficult to modify the interval between sensors and the accidental errors are accumulated. In this work, these disadvantages have been overcome by application of smoothing and a weighted least squares method to the conventional serial three point method for measuring circular profiles. The effectiveness of the improved method has been explained theoretically and examined by computer simulation and experiment.

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The fully automated running of machine tools requires early and automatic detection and prevention of abnormal cutting. Therefore, the purpose of this study is to determine a new approach to detect some kinds of abnormal cutting like self-excited chatter and tool flank wear in turning operation. Using this approach, the occurrence of abnormal cutting is evaluated by a neural network using a spectrum map of cutting tool vibration. The following conclusions were reached as a result of assessing this approach on actual cutting tests. (i) Learning times, where the total RMS error of the neural network with three layers could be within 0.001, reached minimum when number of units in hidden layer was 20, and this number of 20 was also minimum number of enough units to transfer all information about patterns from input layer to output layer. (ii) Capability of this approach to detect self-excited chatter was not affected by presence of tool flank wear. (iii) Width of tool flank wear could be detected within 0.1 mm error because shape of spectrum without self-excited chatter changed monotonously with increase of tool flank wear.

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Recently, vibration of machine tools have become a serious problem because of improving surface roughness of work piece and tool life. In order to improve the structural properties of machine tools, we have developed a new material named ceramic resin concrete. This material have high stiffness, low density, and high logarithmic damping ratio. Therefor, in this paper, availability of tool post using ceramic resin concrete have investigated. It is concluded from the results that tool post using ceramic resin concrete is effective in order to reduce vibration of the lathe and to delay the period of chatter. In addition, middle cutting by a chip of large corner radius and finish cutting by a shaving chip could achieve without chatter from using this tool post.

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