The purpose of this study is to build up a technical method for approximate prediction of a upper limit of confident frequencies, up to which accurate analysis of finite element models are available, and for approximate suggestion of adequate sizes of finite elements, which should form the objective structure models to be analyzed up to upper frequencies of interest. In this paper, according to the proposed method, data-bases of upper limits of confident frequencies are developed for regularly triangular shell elements and the bisected element of them, and applied the finite element modelling of three kinds of mechanical structures. The predictions and suggestions for those finite element modelling corresopnded well with experimentally varified results.

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A rotor core of induction motors consists of many multilayered steel sheets for core which are fixed to a shaft with a shrinkage fit. A bending vibration of rotors with such a rotor core is investigated experimentally. It is shown that the rotor can be modelized by an opening of the multilayered steel sheets and a equivalent Young's modulus of the rotor core. When the equivalent Young's modulus for rotor cores of various shapes is determined and classified, it is possible that the natural frequency of rotors with a rotor core is estimated with the frequency range more accurately.

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This paper presents experimental studies of vibrations of an axisymmetric body in a cavitating leakage flow. The experimental passage is a narrow annular parallel passage. The effect on the characteristics of vibrations and the flow pattern in the passage were evaluated by changing the width of the passage, the downstream pressure and so forth. From the experimental results, the following conclusions were obtained. When the narrow passage becomes choked and the cavitation bubbles are concentrated around the wake, the divergent passage is formed by the columniform bubbles, and self-excited vibrations due to the negative damping occur in the system. Under such conditions, the self-excited vibrations occur significantly when the cavitation number is about 0.2.

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Effects of seismic waves on stability of a multirotor system supported by oil film bearings are investigated theoretically by calculating loci of centers of disks and journals of the system using a time marching method. It will be shown that a 2-disk/4-bearing rotating system, operated at a speed above twice the first critical, becomes unstable when a sufficiently strong shock is given to the system even if the rotational speed is lower than the linear stability limit and the rotors are supported by lemon-shaped bearings, which are considered to have a high stabilizing effect. Both the half-Sommerfeld boundary condition and the quasi-Reynolds condition are used in the solution of the Reynolds equation in the calculation, and the effect of boundary conditions on simulated results is also examined.

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This paper proposes an analytical method to estimate the ultimate strength of seismic isolation systems using high damping rubber bearings against excessively strong earthquakes. In the method, responses of each rubber bearing of the system in horizontal deflection and vertical force are analyzed, and are compared with a breaking limit curve of the rubber bearing represented in a plane with axes of shear strain and tensile/compressive stress to judge whether or not the trajectory of the rubber bearing responses crosses the limit curve. For the rubber bearing response analysis, analytical models for horizontal and vertical restoring force characteristics of the bearing were proposed considering properties in large deformations up to the breaking region. Excitation tests were carried out for an about 0.3 scale model of a base-isolated building supported by four high damping rubber bearings using large acceleration inputs, showing that the analytical results agree well with the experimental results. The tests and analyses showed that the vertical force acting on the bearing was considerably varied according to the horizontal deflection increase, and when a large tensile force acted on the bearing, the rocking motion of the building excited its vertical vibration which caused a fluctuation in the vertical force.

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A vibration absorber was studied to control the dynamic behavior of a rectangular aluminum plate. The absorber consists of an additive mass and a vibration damping composite steel beam. By evaluating the loss factor and the bending rigidity of the vibration damping composite steel using the Ross-Kerwin-Ungar (RKU) model, the length and thickness of the beam and the additive mass were determined in order to tune the resonance frequency of the absorber to any resonance frequency of the rectangular plate. The dynamic behavior of the rectangular plate with the absorber was measured and compared with the calculation. The close agreement achieved suggests that the present method is sufficiently reliable to design the vibration absorber using the damping composite steel beam.

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This paper discusses active vibration control when a system is subjected to unknown deterministic disturbances which are generated by a linear dynamical system. A model reference adaptive technique using a delta operator id considered for control design. This algorithm can be implemented even when a discrete-time model reference adaptive control cannot be designed because of the unstable invertibility of the discrete-time model. This paper points out that it is important to select appropriate design parameters for the algorithm in order to obtain good performance of vibration control. Experimental results show that the control scheme presented in this paper is effecitive when design parameters are determined properly.

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Piecewise linear vibration of the linearly damped mass under a cosine excitation combined with a stationary force, where only one side of the clearance rattles, is computed for checking the author's 1950s' results of rough approximation of the damping effect. (1) Vibration of the 1/2-th order does not occur for 2 c/f beyond 0.108, in complete agreement with the author's old approximation, where c and f represent the ratio of damping to the critical one and the ratio of cosine force amplitude to the body force, respectively. (2) Frequency and amplitude values at the highest and the lowest border frequency of the possible vibration range are compared with the author's old approximations, and are found to be within 0.8% error for f=0.200 and c=0.0100, while for f=0.600 and c-values between 0.0180 and 0.0324, errors are less than 5% provided the clearance-side amplitude errors are neglected.

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Since electromagnetic force is a function of the gap between two magnets, the spring constant has large nonlinearities with respect to the displacement. Hence, the spring constant varies significantly with the initial load. This implies that the linear control theory is not applicable in the range of large displacement. To treat a system with variable initial load and large displacement, the present article presents a procedure for obtaining a linear spring by means of a repulsive-type actuator using permanent magnets and an electromagnet. The analytical expression for the linear spring is presented. Experimental tests were carried out, and the theoretical values are compared with the experimental results.

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A magnetic damper in which opposite poles are arranged by turns has great deal of damping effects as compared with a normal magnetic damper. However the reason of it has not been clarified, and the analysis has not been reported. To clarify the mechanisms of increasing dampings for the damper, this paper presents an analytical results for the eddy current, and the damping coefficient. Numerical calculations are carried out for some important examples, and the results are compared with those of the normal magnetic damper.

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In this report, we will describe a magnetic-spring-type balancer utilizing an effect of a magnetic spring in place of a balancer using either a conventional leaf spring or bar spring. A quite low spring constant can be easily realized by a magnetic spring utilizing a pair of permanent magnets and a steel ball. In addition, there is no vibration mode of higher degree as found in the leaf spring of the bar spring, and a stable measurement can be performed even if the number of revolutions is increased. We have applied this magnetic-spring-type balancer to a VTR cylinder and obtained a measurement accuracy of less than ±5% and a minimum resolution of 2×10<-8> kg-m.

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In this paper, a design scheme for a two-degree-of-freedom (2-D-O-F) analogue controller for hydraulic servo systems is presented, and some problems accompanying the discretization of the controller are discussed. First, a forward dynamic characteristic of the system is designed so as to match a reference model, using pressure and velocity feedback. Then, the feedback characteristic is designed to eliminate a steady-state error for a step/ramp torque disturbance. The analogue controller mentioned above is discretized to be implemented digitally using a few discretizing formulae. Stability analyses are made for the systems with the respective discretized 2-D-O-F controllers to ensure stable characteristics of the systems. Responses of the system to desired step input and to torque disturbances are obtained numerically. Moreover, the effects of the dynamics of the servo valve on the stability of the system are discussed, and it is shown that compensation of the valve dynamics improves the stability and the feedback characteristics of the system.

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This paper discusses the maximum energy converting control for the wave energy converter having two floating bodies subject to irregular incident waves. It is already known theoretically and experimentally that this system has high energy converting efficiency for regular waves. First, the irregular incident waves which are expected to arrive at the floating bodies are obtained based upon our previous procedures for one-floating-body-type energy converter and maximum energy converting conditions are obtained for this two-floating-body-type energy converter. Then, the difference between the predicted behaviors of the floating bodies due to predicted incident waves and the real behaviors of them subject to the arriving waves is fedback using the PD control law to maximize energy converting efficiency. It is shown by numerical simulation that the energy converting efficiency is improved about 10 %.

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This paper is concerned with a control system design for the new type of omnidirectional AGV (automated guided vehicle) without any steering mechanisms. The plant is regarded as a highly nonlinear multidimensional system with parameter uncertainties, so that the conventional control techniques are not available. Here we propose a new control algorithm by combining nonlinear decoupling control with robust simple adaptive control (SAC). Both techniques were developed by one of the authors. The control system then results in single input and single output (SISO) systems by the effect of decoupling control and the control accuracy is assured by robust SAC. The effectiveness of the proposed method is confirmed through numerical simulations.

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In An adaptive control system, parameters of the controlled system are generally estimated assuming that all of the parameters are unknown. In that case, especially in a multi-input multi-output system, parameters increase greatly in number, and it takes substantial time to estimate them. Certain physical elements are often known, and if the information can be used a priori, the number of estimated parameters decreases and the speed of convergence of estimation then becomes faster. In this paper, a priori knowledge of the multi-input multi-output system is classified into three types, and system modeling is done so as to explicitly express a priori information of the controlled system. This method is applied to control a SCARA type robot manipulator. The simulation results show its usefulness.

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This study is aimed at the investigation of the possibility of a problem-solving mechanism in practical engineering problems. Problems are composed of two classes of elements. The element in one class is defined as information flow, and the element in the other class is termed as a device. The information flow has static constraints on the relations in a state observed at one measuring point. The device has multiple constraints which describe relations between states. The information flow and the device have local problem-independent abilities which represent subproblems and their solutions. Problems are formulated by a graph in which an information flow and a device are adjacent to each other. The system of equations which governs the given problem is derived by using the fact that for one physical parameter, the value obtained by static constraints must be equal to the value deduced from multiple constraints in devices.

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This paper deals with an expert system for the recognition and counting of an animal cell for "interferon β type" by image processing and the neural network. These cells are cultured on microcarrier (micro bead) which is 150-200 micrometers in diameter and is floating in culture solution. The image processing technique provides a method of measuring the location of microcarriers and the shape of a cell. The neural network based on the expert system recognizes the overlapping cells and dust from image data. This method is an improved one as compared with the former one in the point that the former one can't recognize overlapping cells. This system provides correct answers at the rate of 83 percent. According to the experimental results, this system will be able to substitute human experts in the counting of cells on the micro bead.

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In order to improve the intelligence of a robot with a tactile sensor, we have discussed basic tactile information, such as slippage and the hardness of a grasped object. In this paper, we produce a tactile expert system which can recognize the material and the shape of the object, and the stability of grasping by means of a reasonable combination of the basic tactile information. Also, in order to discuss the validity of the system, we produced a robot hand which has two plate-type fingers with three-dimensional tactile sensors, and then carried out a series of experiments with the hand and the system. Recognition experiments show that the system can infer seven kinds of objects and that it can control the hand in response to the kinds of instability in grasping.

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The active control system is expected to actively improve the machine characteristics because of the active force subsystem installed on the machine in the active control system. However, the interference between the machine and the active force subsystem existed in a kind of system constructed by an electrohydraulic servomechanism. In this paper, we applied a decoupling control method using the model reference adaptive control to the active control system, and discussed the stability and the control Accuracy obtained in the experiment results with respect to the adaptive gain convergence and the pressure follow-up error. It was shown that the system is stable when the input frequency of the force subsystem is not equal to the input frequency of the machine, and has higher control Accuracy than the simple pressure feedback control.

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The objective of this paper is to solve the minimum time trajectory planning problem of a robotic manipulator under average heat generation restriction. The solving procedure is divided into two stages. In the first stage, the motion trajectory is determined so as to minimize the cost function including both control time and average heat generation of all motors with different Lagrangian multipliers. In the second stage, the optimal Lagrangian multipliers are chosen so as to minimize the control time. To obtain the optimal trajectory in the first stage, we propose a new approach, by which the trajectory is approximated by 5th-order spline function and the optimization is performed with respect to not the spline function coefficients, but to the motion state variables at prescribed node points. To carry out the second stage, two methods are considered. In one method we assume that the control time can be minimized when all actuators generate the respective limited average heat at the same time. In the other we assume that the control time can be minimized when only one of them generates its limited average heat. This method is applied to the trajectory planning problems of a two-degrees-of freedom robotic manipulator with rotary joints and two typical calculated examples are presented.

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In order to investigate the dynamic behavior of robot manipulators, a vibration analysis of the 6-degrees of freedom of manipulators with joint flexibilities and backlashes of transmission mechanisms subjected to Coriolis and centrifugal forces has been developed. The simulation results showed not only the influences of backlash on the dynamic behavior of robot manipulators controlled by the acceleration, velocity, position feedback and nonlinear compensation, but also the occurence of vibrations of the arms due to the presence of a relatively small amount of backlash. Furthermore, it is verified that the backlash should be be controlled about 1'∼2' to keep the position error of arms within the range of the backlash error.

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With the rigid requirements of the automation of the handling of flexible limp seal materials in the industry in mind, this paper deals with a mechanism and control method of a seal-peeling robot. In this paper, we consider the method by which a man peels a seal, and based on this analysis, we make and test a seal-peeling robot. First of all, we analyze a man's seal-peeling task and determine how many and what kinds of basic motions are included in it, and also check how they appear while the task is being carried out. Then we construct a mechanism of the robot based on this analysis. Secondly, we propose a control method for it. We next model the mechanism of glue destruction and analyze how we should control the robot peeling the seal effectively. Finally, we produce a robot based on these analyses and test it to show that it works as expected.

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This paper describes the control design method and the experimental results of the stabilizing control of a inverted pendulum by a one-link horizontal robot. First, the nonlinear equation of motion of the mechanical system consisting of the pendulum and the robot is showed. Then, by applying the optimal regulator theory to the linear equation of motion, the optimal feedback coefficients are derived, and the validity of the control design method are confirmed by the numerical simulation of the stabilizing control of the inverted pendulum. Furthermore, it is showed experimentally that the inverted pendulum can be controlled well by the robot, and the experimental results of the continuous control consisting of the swing-up control and stabilizing control is demonstrated.

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The authors developed a 3D moving robot 'ROBOT CAT' which could control its posture in the air and could perform soft landing. This paper describes the control method of the ROBOT CAT and the experimental results. An animal cat can control its body by turning motion when released upside down from a high place. In order to realize this turning motion, the ROBOT CAT was consisted in two parts (anterior and posterior body) connected with a flexible backbone which has two degrees of freedom of motion. The backbone proposed in this paper operates on two pairs of artificial rubber muscles driven by compressed air. It is possible that this motion is applied to the posture control of astronauts and space structures.

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This paper presents an application of a discrete time adaptive control system to the positioning control of manipulators with low reduction joints. First, an adaptive pole assignment system is constructed to use a simplified discrete time model of manipulators which is a nonminimum phase system. Next, the adaptive control system with a zero phase error tracking (ZPET) feedforward compensator is designed to improve the tracking performance. The comparison of the performance of both methods has been made experimentally for a one-link manipulator. Furthermore, a set of experiments has been carried out for a two-degree-of-freedom planar manipulator with a parallelogram mechanism to show the advantages of adaptive control.

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Using fuzzy linear regression models, an estimation method to detect the human reasoning state in machine operation is discussed. Simple experiments of human operation using computer display show that the change of the human internal state at the reasoning in the operations is reflected in the system parameters of the fuzzy linear regression models. Fuzzy linear regression models are constructed using some fundamental operation data, and fuzziness parameters are calculated by traditional linear programming approaches. The characteristics of the human reasoning state are represented by the fuzziness parameters, and advantages of the proposed approaches, in human reliability are demonstrated by the example of vehicle driving operations.

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Recent advances in intelligent adaptive structures which call adaptively resist external disturbances by changing their forms or configurations have generated interest among designers of space structures. When animals and plants are subjected to many external disturbances, it can be observed that they maintain themselves in two alternative ways: an adaptive way and a robust way. In the latter, they may have strong structures, say, robust structures against any kind of external forces. In this study, primary interest is placed on presenting a basic concept of robust structures and a design method. Detail discussions on robust structures will be presented in following reports, but simple examinations are shown in this report.

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Ultrasonic measurements at high frequency are expected as nondestructive inspection methods for ceramics, composites and functionally gradient materials. Ultrasonic testing and ultrasonic microscopy are two main nondestructive measurement methods being used in industrial areas; the former is suitable for detecting fine flaws in opaque materials and the latter is available for characterization of the materials. In this report, these two methods are used to evaluate ceramics that received heat shock by laser irradiation on the surface. Inside cracks with openings on the surface were measured by ultrasonic testing. Crack shapes were plotted by digitizing and detecting the echoes from the crack surface. It is observed that the cracks, which are perpendicular to the surface, change their direction to horizontal inside the materials and then stop their advances. Surface wave velocity was measured by an ultrasonic microscope. It is found that the velocity at damaged areas is lower than that at less-damaged areas. Ultrasonic microscopy can also detect fine cracks on or near the surface.

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To visualize the oil film formed in the bearing clearance, a porous bronze bearing impregnated with a fluorescent dyed oil is used for the test bearing, and the oil film is rendered visible by a pair of ultraviolet lamps. The photographs are taken by a camera attached to an endoscope inserted into a hollow glass shaft. It is observed that the oil film is formed in the loaded part of the bearing. In particular, it extends over a wide range in the circumferential direction for the relatively small static load and high oil-feed pressure. However, even if under hydrodynamic lubrication conditions, the angular extent of the oil film for the porous journal bearing is significantly small as compared to that for the solid journal bearing. This suggests the previous postulate that the pressure-generating part of the oil film occupies half of the bearing circumference is not applicable to the theoretical analysis of the porous journal bearings, unless unlimited oil is supplied to the bearing gap through the oil-feed hole.

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This paper discusses about how to design and get the angular hypoid gears, when their pinion offsets are given above or below center. It is unable to apply the calculating methods of design and gear cutting to be used in the hypoid gears with a 90-degree shaft angle to the angular hypoid gears as they are. Then the present report describes on several conditions required to expand the design method of hypoid gears heretofore into the angular hypoid gears. Consequently the design elements of the offset, the spiral angle, the cutter radius, the curvature of the tooth trace, and so on have been treated as a positive value usually, but it becomes clear that they have to mark the plus or minus sign for the method of common design.

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In general, the shaft angle of automotive hypoid gears is 90 degrees. Therefore, the design method of an angular hypoid gear had not been investigated sufficiently up to now. Moreover, the tooth spiral of the hypoid gear is generally on the right hand and the pinion axis is offset below the gear axis. Therefore, when the pinion axis is offset conversely, the design method has not been investigated in detail. In the present report, by using basic equations on the angular hypoid gear with an opposite offset obtained in the previous paper, the design dimensions of the angular hypoid gear whose shaft angle is in the region of 70∼100-degrees are shown. As a result, it was found that as the shaft angle increases the pitch angle of the gear increases, but that of the pinion does not so much change and the bias angle which shows the inclination of the tooth bearing changes negatively or positively the sign near the 90-degree shaft angle on the drive-side tooth surface.

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The rotational motion of a gear pair with the equivalent profile is analyzed under load. The path of contact consists of two different curves connected discontinuously. In its continuous region, equations of motion are solved and the fluctuated tooth load is calculated. At the point where it is discontinuous, the impact load is calculated from the difference of angular momentum. The dynamic incremental load on the tooth surface during one pitch can be given by a periodical function combined with the fluctuated load and the impact one, which is expressed through a Fourier series.

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The newly developed method is applied to the equivalent profile with a symmetrical convex curve, with which most modified tooth surfaces for practical use can be expressed approximately. An analytic equation for the amplitude of the dynamic increment of tooth load is derived, which is written by (1) Dimensions (moment of inertia, base-circle radius and number of teeth), (2) Amount of modification and (3) Operationg conditions (rev./m. and torque). It can explain the experienced facts over gear noise and give indexes on how to design and produce gear pairs in order to reduce noise and vibration.

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The modification of tooth profile (MTP) is very often used for reducing the rotational vibration of a pair of gears for power transmission. But the current MTP cannot eliminate the vibration from a pair of gears completely, because the MTP is not obtained by exact theory. This paper develops the optimum modification of tooth profile (OMTP) of power transmission spur gears to make the rotational vibration equal zero. By minimizing the total equivalent exciting force (TEEF) of a pair of spur gears, the OMTP in the case of any contact ratio can be simply obtained. The magnitude and the shape of the OMTP change markedly with the contact ratio ε, in particular, the concave shape of the OMTP is obtained in the case of ε &le; 1.1. The authors applied the OMTP to active spur gears, and found that the vibration calculated numerically by the exact nonlinear equation is zero. The slight effect of the variation of the contact ratio, the magnitude of OMTP and the external static load is also investigated.

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The cermet-tipped finishing hob shows good results in economical and productive finishing of tooth surfaces. As the cermet finishing hob has poor grindability, it takes a long time to manufacture the cermet hobs and it is difficult to keep the hob tooth profile accurate. In this paper, small lands of zero relief angle are made on the cutting edges of the cermet finishing hob in order to manufacture a highly accurate hob. By finish hobbing tests with the cermet hobs having various land widths, the hob wear and the tooth surface roughness vs the width of lands are investigated. The hob with the small land width of about 0.1mm is superior in wear resistance and improvement of the tooth surface roughness to those with land width greater than 0.2mm.

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As the acoustic power of noise radiated from gear transmission is far smaller, by ten to hundred thousands times, than the transmitting power of the gearing, even a deviation of tooth flank shape in several micrometers already has a very big influence on the running noise of the transmission. Gears are in general manufactured under the tolerance limit specified by designers, but the detail of geometrical shape of each tooth flank is not the same. In addition to this, the alignment of gear shafts in operation is changed by clearance of the bearings and elastic deformation of the system. The scattering in the shape of tooth flanks and the change of the alignment give a considerable influence on the nature of vibration excitation caused by tooth meshing. In practice the detail of the figure of each tooth flank of a gear is not usually same and the exact status of gear shaft alignment is not known. These make the prediction of gear noise extremely difficult. This paper proposes a method of data analysis for vibration excitation due to tooth meshing of gears for predicting running noise of gears. This method brings a good correlation between the calculated vibration excitation and gear noise of an automatic transmission of a passengers car. Basing on this method, a procedure to design silent gears, considering manufacturing capability of the work, is proposed.

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Miter gears are the most used of all bevel gears. Now that cutting and grinding methods of conical involute gears with a cone angle of 450 have been established, miter conical involute gears may become the most useful of conical involute gears. However, the tooth bearing of miter conical involute gears has not necessarily occured in the desired position. In this paper, first a new design for miter conical involute gears is developed, making it possible for the tooth bearing to occur in central part of the tooth width. Second, the test gears are designed and made. Finally, the tooth bearing tests are performed, and the design applicability is proven.

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It is one of the most important subjects in the industrial gear field to design gears fitted for reduction of material cost. The force-fitted gear is one of the promising gears which meets such a requirement. Some researches to elucidate the characteristics of force-fitted spur gears have been carried out for several years. However, the design method of force-fitted helical gears has not yet been established. Under such a present situation, taking up the research of a design method of force-fitted helical gears as the subject of the present paper, the allowable limits of rim thickness and interference were discussed from three points of view: stress at the root fillet of the gear tooth, dynamic slipping torque and stress in a tangential direction at the force-fitted surface of the gear rim. Consequently, the design procedure of the force-fitted helical gear was shown.

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Experiments on a transmission error having a period of one revolution of the belt in a polyurethane synchronous belt drive were performed in the quasi-static condition under an initial tention. The experimental results were compared with the computed results which used the results of measurement for the production error in the belt. It was confirmed that the transmisssion error is mainly caused by a single pitch error and the change of the product of the sectional area of the load carrying cords and the modules of elasticity of the belt, SE. In the case of the belt used in this study, the change of SE had the most influence on the transmission error. As the tendencies of the experimental results and the computed ones coincided well, the methods of measurement for the single pitch error and SE, and the methods for arrangement of these values used in order to compute the transmission error were right.

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The method to get higher productivity of the hourglass wormgearing is developed. And the wormgearing has the high performance. For this purpose, the method to manufacture the worm by a pinion cutter is developed. And the method to analyse how the cutting blades generate the worm tooth surface. And also the method to calculates the true profiles of the worm tooth surface generated by the pinion cutter blades. And these calculating methods can be available for any kinds of gearing manufactured by any types of cutting tool.

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Recently, many kinds of material have been cut by CO₂ laser, but the cutting accuracy is variable according to materials such as mild steel, stainless steel, aluminum alloy and copper. Some investigations were carried out to elucidate the accuracy in laser cutting. In this report, the polarization characteristics of light are studied. A simple model to show the accuracy concerning polarization was introduced previously, and cutting tests were carried out in order to validate those relations. It was confirmed from this experiment that the reflectivity of material was important for the accuracy, and the reduction of reflectivity improved the accuracy. Moreover, the cutting accuracy could be improved by means of a combination of the condition parameters.

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Aerodynamic noise caused by a circular cutting tool is reduced by adopting special tooth shape. This tooth is machined a longitudinal slit throuh the face of the tooth for the purpose of ventilation. A reason of the aerodynamic noise reduction is that a vortices generated behind a tooth are controled by a self-jet from a slit of the real slit tooth. From the experimental results, it is possible to reduce the aerodynamic noise sufficiently by using the real slit tooth. This paper presents the results of an investigation into the influence of the slit width and tooth spacing on the noise reduction. Furthermore, the influence of the slit tooth to the St number on the aerodynamic noise is clarified from the experimental results.

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A new shape measuring method for bodies with free-form surface is proposed. The measuring method is composed of a data samplimg by the side surface contact of a cylindrical probe with the free-form surface and a numerical data processing procedure to generate an offset surface. The accuracy of the data processing algorism, especially the influence of spacing of data points on error of the generated offset surface, is examined by mathematically defined three-dimensional bodies. Using d golf club as an example, the data obtained by a conventional point probe is compared with the data of the offset surface generated by the proposed method. Both data sets show good agreement.

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For purpose of 3-dimensional (3-D) shape inference from the image brightness, it is necessary to know the direction of light. In this paper, we propose an iterative algorithm for estimating the direction of light from the brightness and the occluding boundary. From the numerical results, it is found that the algorithm reaches a reasonable solution in a small number of iterations. Furthermore, we consider the convergence of the 3-D shape inference algorithm, and show that the smaller the difference between the direction of line of sight and the direction of light, the faster the algorithm converges.

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It is clear that CAD systems must have nongeometric information of the artifacts with geometric information. In this paper, we propose the designers' intention model which includes the information of designers' intentions and operations. The designers' intentions and operations which are related to particular artifacts must be described by the designers themselves. In order to describe them, DPL (Design Process Language) is proposed. DPL interpreter is also developed to construct the designers' intention model from the DPL description given by designers which controls other CAD tools including the geometric modeler. Through the constructed designers' intention model that is connected with the geometric model, other designers and process planners can understand the meaning of shape features as to why they are required and generated by the designers. Through case studies, it is clarified that DPL and designers' intention modeling system work as a communication tool among product designers and process planners.

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Metallic materials with thermal barrier coatings are available under high temperatures (about 2000K). However, it is unknown whether or not the coating materials can resist repeated thermal shock. The authors have been developing laser spraying methods which can easily form metallic or ceramic coatings. In order to examine the characterestics of the coatings produced by the laser spraying methods, a new testing apparatus for repeated thermal shock was needed. Therefore, the testing apparatus was made on an experimental basis. The heat source of the apparatus was a carbon dioxide laser beam (maximum power supply: 5kW) and the tested materials were titanium nitride layers which were coated on mild steel plates by means of laser spraying methods. As a result of testing, the surface temperature reached 2000K in 4 seconds in the case of 290 W/cm² (power supply: 4kW; beam diameter: 42mm), and it was possible to repeat thermal shocks between room temperature and 2000K (at the surface) or 1000K (at the bottom of the coating; thickness: 1mm) at the rate of 3 times a minute.

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