The exact solution to the initial value problem of a string whose length varies with time is presented. The string supported at both ends is replaced by an infinite string, and one supporting point moving with time is replaced by a moving concentrated load whose amplitude is an unknown function of time. The wave equation of the infinite string is solved analytically, and the solution that satisfies the boundary conditions of the finite string is obtained.

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Based on Eular equations and a continuity equation for describing the motion of two liquids of different density contained in a rotating cylinder, the governing equations for fluctuating velocity components in γ, θ, and z directions and boundary conditions are derived. For highspeed rotation of the cylinder, fluctuating pressures in each liquid are obtained by assuming two-dimensional motion of liquids and applying the Galerkin method to a boundary condition on the pressure, and the fluid force acting upon the cylinder is then obtained. Applying this fluid force to the equation of motion of the rotating cylinder-shaft system, stability criteria are obtained by using the harmonic balance method. The theoretical evaluation of the stability condition in terms of rotation speed and liquid-thickness ratio is compared with Kaneko's experiment and our theory offers very good agreement with the experiment. For low-speed rotation, no instability occurs.

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Nonstationary vibration characteristic during acceleration through a critical speed of a 1/3-order subharmonic oscillation of forward precession is investigated. The following results are obtained: (1) Resonace curves exist separated from the zero-amplitude solution which is stable at any rotating speed ω. If there exists an initial disturbance, the solution jumps to the resonance curve and the subharmonic oscillation may occur. (2) The maximum amplitude depends not only on the angular acceleration A but also on the initial disturbance ΔP, the initial rotating speed ω_s and the initial angular position, Ψ₀, of the unbalance. And with respect to the initial angular position Ψ₀, the maximum amplitudes vary periodicaly. (3) The amplitude may grow infinitely when the angular acceleration λ takes a value between two critical values λ₁ and λ₂. If the angular acceleration is outside of this range, the rotor can always pass the critical speed with a finite maximum amplitude. In addition, characteristics of 1/2- and 1/3-order subharmonic oscillations of backward precession are discussed briefly. From comparison of the results of all kinds of subharmonic oscilations, it becomes clear that the periodicity of the maximum amplitude for Ψ₀ has strong relation to the periodicity of the spring characteristics around the equilibrium position.

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An experimental identification method for qualifying analytical models of a structural dynamic is proposed. The method can be applied, at the design stage, when assembling a set of sub-structures. Its major feature is to represent correctly the equilibrium of forces within each substructure. The characteristic representation of a substructure obtained from the experiment consists of a set of eigenfrequencies, the corresponding modal damping coefficients and some boundary factors. These characteristics are determined by measuring the excitation forces, and the mathematical algorithm employed guarantees that the measured forces will be conserved in the analytical representation of the substructure. Only a few data points, which can be obtained from dynamic tests with sinusoidal base excitation, are required. Two example problems have been analyzed by means of a finite-element package and also tested experimentally, it is shown that these two sample problems yield consistent results.

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The loss factor of a viscoelastic damping material is commonly measured by the half-power method using a composite beam with the viscoelastic layer. However, the method involves problems of large measurement errors and of the beam shape, which does not represent practical applications. This paper discusses the relatinship between vibration modes and measurement accuracy, and presents specimen dimensions which materialize the bending mode for the accurate loss factor. The vibration modes are classified into torsion, warping, torsion and warping, and bending. According to the discriminants this study induces, the beam shape has satisfy (l/b)(d₁/b)≥0.06 to materialize the bending mode. The loss factor of the viscoelastic damping material obtained by the composite beam within the dimension limits and the Oberst theory had good agreement with the loss factor of the same material measured by the nonresonance forced vibration method, and was certified to be sufficiently accurate.

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A new mode-superposition technique with higher accuracy and efficiency was proposed by the authors in Part 1. This paper applies the technique to eigenmode sensitivity analysis for a structural system or a coupled acoustic-structural system. It would be shown that the use of a new mode-superposition technique greatly improves the convergence of a modal sensitivity analysis, and makes it possible to calculate the sensitivity with better efficiency than Fox-Kapoor's modal method and Wang's modified modal method and also with better efficiency than Nelson's Method. The theoretical results are verified through application of the method to a box structure and a practical vehicle interior noise problem.

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An airbag system is effective as a countermeasure of automobile safety. The airbag safety device protects a passenger from injury during a car crash. This paper describes the feasibility study on the applicability of the airbag system for protecting passenger during a car crash. Using the simulation program "MADYMO", the following results are obtained: (1) required velocity change at which the crash sensor sends the firing signal to activate the airbag. (2) optimal time at which the sensor is required to send the firing signal to the airbag.

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To upgrade the riding comfort of the 0 Series Tokaido-Sanyo Shinkansen electric multiple-unit train, the suspension components of the bogies are successfully developed which improve the damping ratio of lateral body hunting motion. The result of field tests shows that the frequency of lateral body acceleration decreases about 1/1O as compared with the original bogie.

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This research paper presents a new method of measuring the length of a pipe by using sound frequency. A sweep signal is radiated from the speaker toward the inside of the pipe. The sound pressure at the resonant frequency of the air column in the pipe indicates the largest value. The length of the pipe to be measured corresponds well to the resonant frequency. The phase. locked loop device is adopted to obtain the stabilities of resonation and frequency. A frequency counter with a reciprocal mode is adopted for higher resolution within a shorter time period because of low frequency.

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Impulsive pressure induced on a thin plate by fluid flow is measured by piezoelectric ceramics. Two piezoelectric ceramic transducers are put on the inner side of a plate in contact with fluid and the outer side. The output voltages from each of the piezoelectric ceramics are summed to cancel the effect of the plate-bending deformation. The summation of voltage histories is converted to impulsive pressure according to the calibration of piezoelectric ceramics by the longitudinal impact test. A generator of impulsive pressure is constructed to verify this method. As experimental results, this method can measure impulsive pressure on a thin plate without changing the rigidity of the thin plate, in as far as the plate is deformed by bending.

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This paper discusses characteristics of coarticulation in terms of lip shape and proposes a coarticulation model for lipreading coarticulated vowels. The characteristics are described by the width and height of the lip shape and the distance between the upper lip and the bottom of the jaw. The model consists of a conversion matrix and an average shift vector for the above three parameters. The conversion matrix converts the covariance matrix of parameters for an isolated vowel to that for its coarticulated vowel. The average shift vector shifts the average vector for an isolated vowel to that for its coarticulated vowel. The effectiveness of the model is demonstrated.

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Since vibration excited by a flaw from assembled ball bearing is very weak, the flaw signal is usually buried in background noises. In order to detect such a weak signal, a new analytical method is proposed in this paper. The method makes use of a bispectrum analysis for flaw diagnosis in the assembled ball bearing. As previous works in this field, tests were performed for ball bearings which were not assembled in a machine. In those tests, vibration signals from flaws had relatively high S/N's. However when the flaw diagnosis of a ball bearing installed in a machine is intended, a new signal processing method must be developed to reduce the noise level. In this study, we use ball bearings with artificially dented flaws on the innerrace. The bearings are installed in a rotating machine. Then vibration of rotating machine is measured and flaw signals are extracted from background noises. Flaw signals are analysed by the bispectrum method. The newly developed bispectrum analysis proved to be a very effective method for vibration signals of low S/N obtained both from simulation and from ball bearing tests. This bispectrum analysis seems to be applicable to an on-line flaw diagnostic method for the ball bearing and other mechanical elements installed in a machine.

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The master-and-slave control system should be extensively implemented for the in-service inspection of operating nuclear power stations or the decommission of retired plants. The performance of this system depends on the intelligent slave. In this paper the degree of intelligence is approximated by the given amount of prior knowledge or suggestions. This paper aims at improving the general problem solver (GPS) by incorporating the learning process in order to solve the puzzle of the "monkey and banana". The monkey in this puzzle may be a reasonable alternative to represent the intelligent slave. Also, this paper deals with fuzzified problem solving since the master's command is not always crisp to the slave.

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This paper is concerned with a new discrete-time adaptive control scheme for pneumatic servo systems. In order to reduce the number of unknown parameters, a nonminimum phase discrete-time model of the control object is used to construct the proposed adaptive control system. Since the usual model reference adaptive control scheme cannot be applied to nonminimum phase plants, we propose a quasi-model-reference adaptive control system which includes an adaptive precompensator. The asymptotical stability of the control system is proven under a certain condition. The validity of the control system is confirmed experimentally.

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When neural networks are applied to servo systems, the computation time of the control algorithms cannot be neglected, and the time period of on-line learning is expected to be shortened, considering the life span of the plant and the saving of electric energy. In this paper, we first proposed a design method of digital control systems using neural networks. In this method, the future information of the desired value is used as the input of the neural network and the computation time of the control algorithm is taken into account. Secondly, we presented an off-line learning method based on an approximate model of the servo system. The effectiveness of the proposed control systems and the off-line learning method is demonstrated by experiments and simulations on the control of a parallelogram link robot manipulator of 2 degrees of freedom.

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This paper presents an active suspension with preview to railway vehicle systems using the stochastic optimal control. The railway vehicle is modeled as a linear system with three degrees of freedom subject to irregular tracks, which are described by first-order systems with Gaussian white random inputs. The velocities in bounce, roll and pitch modes of the body of the vehicle, and the irregular tracks ahead of the vehicle are in noisy environment measured by using sensors mounted on the body of the vehicle. The state variables of the railway vehicle systems are estimated by using the Kalman filter, and the active control is determined by minimizing the given performance index. The numerical example shows the effectiveness of the proposed active suspension with preview, and the control performance with the preview time as a parameter.

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The use of ring rolling mill machines has been increasing use in recent years because of its superior product precision and energy efficiency in comparison with casting, machining and other ring manufacturing processes. We designed the ring rolling mill which controls the ring outer diameter growth fate. The ring growth rate is controlled by the mandrel pressing velocity which consists of feedforward (FF) control and feedback (FB) control, and sets the integral value of I control to zero when a point of inflection of reference velocity is detected. The control system gave high accuracy and fast response simultaneously compared with conventionl PI control, and greatly contributed to the improvement of the quality of products and the efficiency of the mil.

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The superheater temperature in a boiler plant of a thermal power station should be con-trolled with high precision in order to satisfy plant efficiency, safety and other requirements. However, it is not easy to keep the temperature constant when the power demand of the generator varies greatly. In order to support the PID control system used at present, we have developed an adaptive control system with a feedforward compensation of disturbances, varying sampling time and varying parameters, both depending upon the power demand. Through simulation study, it is shown that an adaptive control system can reduce the control error greatly.

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We developed a new type of parallel bicycle with a working arm and a controlling arm. By using these arms, the robot can vary its configuration and change locomotion mode according to the working conditions or environments. In the previous paper, several kinds of configuration and locomotion mode were realized by using gain-changing control method. In this paper, torque control method was proposed and applied to the standing up motion and braking of falling down of the robot. The experiments shows that the torque control method is better than the gain changing one because of the smooth and high speed motion without any critical vibration. Furthermore, we succeeded in soft landing of the falling down motion of the robot by using self-learning control method applied to provide the input torque. According to the experimental results, this type of the robot can be expected to play active roles in service or maintenance use.

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This paper describes a motion control method of a two-link horizontal bar gymnastics robot with passive joint by use of a feedforward control based on the inverse dynamics. The direct current servomotor is installed at only the second joint, and the first link is controlled by the coupling forces and the moments between the active and passive joints. The dynamic behavior of the robot is described by the use of a system with two equations of motion. In the design of the control system, first, the feedforward control angle of the first joint is obtained by the numerical simulation with the first equation of motion for the desired second joint angle. Then, the feedforward control torque of the servomotor is computed by applying inverse dynamics to the second equation, and the feedforward control voltage is obtained in consideration of the electric circuit of the servomotor. Furthermore, the experimental results are demonstrated, and the availability of the present motion control method is confirmed.

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It is very important to adjust the dynamics of a robot in order to achieve a natural behavior under the complicated interaction between the robot and the external environment. With respect to dynamic walking control of the quadruped locomotion system, a compliance control is discussed. In this paper, the stiffness and dumping of tiptoe motion in the coordinate fixed on the body is controlled at each configuration of the leg. The hierarchical control structure is adopted. In the lower level, torque feedback control at each joint is executed by using a torque sensor which was developed to accurately measure the torque of the joint. In the upper level, the reference torque signal to the lower level is generated to realize the desired compliance. The compliance control is applied in the three-leg-supporting phase and in the touchdown of the swing leg. The desired compliance is designed to absorb the vibration caused by the collision at the touchdown and not to prevent the forward movement. The effectiveness of the proposed control strategy is confirmed by experiments using walking robot 'COLT-3'.

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This paper deals with neural network applications for robotic motion control where the controller is applicable to the position and force control of robotic manipulators undergoing collisions. Collision phenomena have strong nonlinearity and are high-speed phenomena, so it is difficult to sense collision phenomena and to control robotic manipulators undergoing collisions. The neural servo controller is based on the neural network which has integrated time delay elements, so that the neural network can learn the nonlinear dynamical system. Therefore, the neural servo controller is effective against collision phenomena. We adopted a Hertz-type model with an energy loss parameter to express the impact force between the manipulator and unknown objects. Simulations are carried out for the case of hybrid control of a one-dimensional robotic manipulator which handles unknown objects using proximity sensors. The results show that the neural servo controller can sense and control collision phenomena. Moreover, they show the relation between the intelligence of the neural network and information from sensors.

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The objective of this paper is to verify the effectiveness of the control method and sensitivity analysis by experiments which were described in the previous paper. Here, a two-link flexible robotic arm with three degrees of freedom is employed in experimental equipment, and force sensors and encoders are employed as sensors. In particular the force sensor is used to suppress the vibrations of the flexible arm. First, it is shown that the residual vibrations in positioning control can be suppressed by the state feedback control method with optimal gains. Second, it is shown that the closed-loop system by using the optimal control theory becomes unstable when parameter's uncertainties such as the second arm's length or payload weight are included. Thus the allowance of parameter variations given by this paper is verified by both simulated and experimental studies.

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An active damping control method has been applied to achieve quick positioning for a 2-link flexible manipulator. The 2-link flexible manipulator is regarded as a distributed parameter model in consideration of the mutual interaction between links. A 6-input, 2-output LQG controller was adopted as the active damping controller to avoid coupled vibration. Then the robustness against variations of the arm's configuration and its tip mass were evaluated in the time and frequency domain. Also evaluated was how a nominal arm model in the LQG controller design should be set to maintain stability against wider variations. These evaluation results have been confirmed by experiments. As a result, (1) it was impossible for the LQG controller to maintain stability beyond the boundaries of the arms configuration, and (2) a LQG controller designed with the arm model of maximum tip mass was able to maintain stability against wider variations of the tip mass.

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In the first paper, the control methods and experimental results on the postual and driving control of the arm-wheel type locomotive robot were reported. In the second paper, the walking forms and control methods of the leg-leg type model which is a kind of quadruped walking robot were investigated. In this paper, the authors discuss static and dynamic stability of the arm-wheel type model according to the compound gravity center feedback method proposed in the first paper. Firstly, the static stability of the robot is analyzed and a generalized postual control method is derived. The dynamic stability of this control method is verified by the analysis based on the Routh-Hurwitz's criterion and the root-locus method. Using the results obtained by the analysis, we can find satisfactory stability condition whose effectiveness is confirmed experimentally. Furthermore, the effects of magnitude of the feedback gains upon the postural stability have been discussed and a designing method of the control system of the inverted pendulum type locomotive robot has been proposed.

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This paper reports the control methods and experimental results on the postural change and jumping motion of the arm-leg-type locomotive robot which has a twin leg, an upper structure on its driving axis and double controlling arms suspended from the upper body. In order to stabilize and change the posture of the robot, the feedback control method based on the compound gravity center among the body, the arms and the legs was applied. The compound gravity center was also controlled according to the inclination of the postural angle. Furthermore, we have successfully achieved a jumping motion by sequentially controlling the orbit of motion of the legs. Switching between the torque control and the PID control methods is useful in jumping motion of the robot.

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This paper deals with a computational method for plant pipeline information using the visual method for the plant maintenance robot. For this purpose, the fiber grating (F. G.) method is employed in this paper to calculate the direction and radius of pipeline which generally has a cylindrical surface. The F. G. is itself made of optical fibers, through which the laser beams make discrete dot patterns without any mechanical scanning structure, unlike other scanning methods. Thus the proposed method has the following advantages: (1) it is possible to obtain 3D image information by means of a single camera; (2) the processing time is generally shorter than that of the other scanning methods. Although the proposed method do not give a fine analysis method of image data like the common scene analysis, it is suitable for obtaining rough information on the working environment of robots. This paper introduces a computational method capable of obtaining pipeline information, (the direction and radius) without the influence of the rotation of pipeline. Some experimental results are also shown here to verify the proposed method.

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This paper deals with a recognition method of plant pipeline direction (rotational angle in the vertical plane and in depth) by the neural network applications using the vision method for the plant maintenance robot. For this purpose, a fiber grating (F. G.) method is employed in this study. The F. G. is itself made of optical fiber, through which the laser beams form discrete dot patterns without any mechanical scanning method. Thus the proposed method has the following advantage: the processing time is generally shorter than that of other methods. Although the proposed method does not give a fine analysis method of image data like the common scene analysis, it is suitable to obtain rough information on the working environment of robots. This paper introduces the applicability of the neural network to the discrete dot pattern by F. G. for the recognition of plant pipeline direction (rotational angle in the vertical plane and in depth). Some experimental results are also shown here to verify the proposed method.

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A free-flying space robot consisting of a satellite main body and manipulator arms is expected to perform lmportant tasks in space. The attitude of the satellite changes when the manipulators are operated. This means the orientation angles would be controlled by an appropriate planning of the trajectory for the manipulators. For good robot performance, trajectory planning methods are required to control the orientation angles of the satellite. In this paper, a neural network is employed to generate the trajectory for the manipulators to control the orientation angles of the satellite and simultaneously to minimize the operational efforts. The proposed algorithm is applied to a free-flying robot with a simple two-link manipulator. By numerical simulation, the optimal trajectories are computed for any change of the orientation angles, and the effectiveness of the proposed algorithm is verified.

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Space robots consist of a free-flying satellite base and manipulators with structural flexibility to meet the requirements of a lightweight system. The motion of the manipulators influences the positions and orientations of the satellite base because the system has no fixed supports. The motion of space robots also induces vibrational motions of structurally flexible manipulators. To control such complicated space robots, their dynamic characteristics should first be understood. A mathematical model of a space robot with structurally flexible manipulators is developed in this paper by using a finite-element method. An extended local PD-control scheme to control the structurally flexible manipulators on the satellite base is proposed. The scheme presented is very simple and the stability of the closed loop system is proved by Liapunov's direct method. The effectiveness of the control scheme is verified by numerical simulation.

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This paper deals with an experimental investigation of the control performance of an aquarobot hand at approaching and grasping a floating object in water. The fluid dynamic interaction between the manipulator motion and a floating object was formulated in the form of linear state equation, and using this formulation the error state between the robot hand position and the object was predicted for m-steps time in advance. This prediction was used to determine the feedback gain when the hand came to the region where the fluid dynamic interaction appeared between them. This prediction control showed a good reduction in the time needed to catch the floating object of about 50% compared with that in a conventional PD Control.

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Recently, the reduction of cost in the field of gears has become a serious problem, and consequently, the force-fitted gear has become a subject of attention. Although some studies on force-fitted spur and helical gears have been presented, there have been very few studies hitherto which deal with force-fitted bevel gears. In view of such a situation, the force-fitted straight bevel gear was chosen as the subject of this study. That is to say, stresses at the tooth root of the straight bevel gear caused by force-fitting were examined. The experimental results were also compared with computed ones by the finite element method. Moreover, a practical formula to determine the stresses at the tooth root was discussed. From this study, distributing conditions of stresses at the tooth root of the force-fitted straight bevel gear were clarified.

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Displacement of the worm axis relative to the wheel axis under load is considered to be the helical movement rotating about the instantaneous axis. In order to avoid the influence of the displacement of gear axes under load upon tooth contact, the authors propose that the surface normals should be intersected perpendicular to the direction of helical velocity of the displacement. This idea was applied to the gear design using all hourglass-worm gearing whose worm tooth surface is generated by the grinding wheel with an involute helicoid. Numerical analyses indicated that as much as 80% of the theoretical area of the utilized gear contributed to meshing at their estimated displacement positions.

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The effects of the combination of hardness and surface roughness on the surface durability of medium-hardness gears (HB300∼HB400) are examined by using a disk machine, when the pinion with a smooth surface is harder than the gear with a rough surface in order to improve the load-carrying capacity. In increasing the initial hardness of the disk with a smooth surface (1μm Rmax) in comparison with the hardness of the disk with a rough surface (10μm Rmax), the pitting life and wear resistance of the disk with a smooth surface are improved. But the pitting limit of the disk with a rough surface is not improved. These facts indicate that it is necessary for the pinion with a smooth surface to be harder than the gear with a rough surface in order to improve the surface durability of the pinion rather than the gear, when only the pinion tooth surface is smoothed between a pair of gears.

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A new method of finish rolling is proposed to finish tooth surfaces and fillets at roots of gears in one pass, using a screw-shaped tool. A preliminary experiment of finish rolling of only tooth surfaces of spur gears is done with a trial constructed apparatus. Gears with good tooth profile accuracy and good surface finish are produced without any modification of the tooth profile of the tool or the work by this method. Then the tooth surface of the work is markedly hardened.

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The objective of the research reported in this paper is to study fatigue crack initiation and propagation behavior under cyclic rolling-sliding contact using a notched cylindrical specimen. Since flaking and preflaking cracks were limited in notched area where contact pressure was high, the surface appearance in notched area could be observed continuously by the replica method. While surface cracks were not found until 97% of the flaking life in the case where clean oil with high viscousity was used, surface crack initiations at surface flaws of indentations were observed on specimens tested with dirty of low-viscous oil. It was also found that the crack propagation rates were almost constant when the crack length was greater than 0.3mm and that crack propagation rates in specimens lubricated with dirty oil are the same as of smaller than those with clean oil.

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The shapes and thicknesses of the elastohydrodynamic oil films formed between a steel ball and a glass disk are measured using optical interferometry and compared with the established EHL theory. It is found that film profiles and thicknesses are markedly different from those predicted by the EHL theory, and their discrepancies depend upon the non-Newtonian response of oils and the difference in elastic moduli of contacting surfaces. As a result, it is concluded that in order to have a clearer understanding of the cause of surface failure and methods for its prevention, the EHL theory should be reconstructed by considering the solidification phenomenon of lubricating oils and pressure components parallel to the contacting surfaces.

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This paper describes the derivation of a new type of modified energy equation including turbulence and surface roughness effects and presents an adiabatic approximate solution for the static and dynamic characteristics of an 180°partial journal bearing with homogeneous surface roughness. Applying the modified turbulent lubrication equation and energy equation to the finite width partial journal bearings, the static and dynamic characteristics such as pressure and temperature distributions, load carrying capacity, friction coefficient, whirl onset velocity and so on are obtained numerically. In the numerical analysis of the modified energy equation, the adiabatic condition is assumed and then the heat transfer terms in the energy equation are omitted. The numerical results are indicated in graphic form for the various combinations of Reynolds number and relative roughness. Moreover, some numerical results of static characteristics are compared with the experimental results.

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The frictional behavior of alumina ceramics was investigated at various temperatures up to 1200°C. The coefficient of friction decreased with increasing temperature and this temperature dependency became more pronounced as higher contact pressures were applied. Wear loss at room temperature could be interpreted as being caused by one of either two different behavior modes. These have a rate difference of a factor of ten. At temperatures higher than 800°C, the wear loss was far less than that at lower temperatures and a smooth, flat friction face, which should be responsible for the low friction coefficient and small wear loss, was observed.

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An electric connector is produced by press working with a progressive die. The surface of the workpiece is roughened by the compression process, and this roughness is harmful to the subsequent gold plating. Before clarifying this roughening mechanism, the deformation properties of a copper alloy with 0.645mm thickness in high-speed compression and the change in the macroscopic surface morphology, which affected the microscopic surface roughening, were examined in this study by a drop tester. The impact velocity and the impact energy were varied. The viscosity of the lubricant was also changed. The reduction ratio of the thickness of the workpiece was affected by the viscosity of the lubricant. The surface morphology was classified into five types depending on impact velocity and viscosity. Surface upheaval was observed when the lubricant flew out between the surfaces. Surface depression was caused by the squeeze effect of the lubricant.

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The working process of helical compression springs usually comprise a the process which includes coiling, cutting and end grinding. The working process with a synchronous cutting machine, which has been developed by the authors, can unify these three processes. Using this new method, the process with the coiling machine becomes continuous and the wire feed is equalized. Therefore, productivity is improved. In this paper, improvement of working characteristics is described when the forced rotation coil holder is loaded on to the synchronous cutting machine, and its optimal condition is estimated by geometrical analysis.

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There are many papers that deal with the edge quality of mild steel that has been cut by a CO₂ laser. Most of these papers, however, refer to a thin plate, less than 6mm thick. For plates thicker than 9mm, as the cutting speed decreases, the difference between the cutting speed and the oxidizing reaction speed Produces an even rougher edge. Therefore, CO₂ laser cutting cannot provide versatility over a wide range of thick plate applications. This study deals with improving the edge quality of mild steel 12mm thick. Using high-frequency, low-duty pulses the groove size produced by the oxidizing reaction is reduced. Moreover, a beam energy of higher peak power can be transmitted through a greater thickness than possible during CW cutting. As a result, the pitch of the grooves generated on the cut edge is reduced, and the edge quality is greatly improved.

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The effect of environmental temperature change on the thermal deformation of machine tools is analyzed for the case of a machining center, both by experiments and by unsteady three-dimensional finite-element analyses. It is clarified that the air temperature surrounding the machining center varies depending on the altitude and the air flow condition, etc., and the amplitude of daily periodic variation also changes from one place to the other. The surface temperature of the machining center follows the ambient temperature with a time delay of 2 to 3 hours, but the amplitude of temperature change is slightly smaller than that of the ambience. The unsteady variations in the relative displacement and inclination between the main spindle and the work table of the machining center due to the ambient temperature variation are clarified quantitatively by the experiments and the finite element analyses.

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Orbital rotary flaring of thin walled copper tubes with a cylindrical tool has been experimentally investigated to improve the flaring limit of the tubes. The results are summarized as follows: (1) Flaring limits were determined by the onset of necking and two kind of bucklings. (2) The flaring limit of hard tube is higher than that of both press forming and orbital rotary forming with a conical tool. Heigher flaring limit is obtainable with a cylindrical tool having smaller diameters and higher feed speeds. (3) A modified inclination method is introduced to prevent the necking and the buckling at tool inlet. Then, it is found that the buckling and necking modes are prevented under the proposed preventing condition.

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In this paper, the effect of bending load on bending stiffness of a wedge-type power chuck with three top jaws is investigated. Bending tests of works with different diameters were performed in which the deflection of works were measured. The investigation showed that the bending stiffness of the chuck-work system significantly depends on the bending load when the bending load is increasing. The bending stiffness varies with gripping force and the ratios of the diameter of works to the gripping length of jaws. There is no effect of the bending load on the bending stiffness when works are clamped under the gripping condition in which gripping lengths are 0.8 times an large as work diameters. This gripping condition is also acceptable for the damping efficiency of the system.

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In this paper, an investigation of gripping characteristics of a wedge-type power chuck with three top jaws is reported. Bending tests and impulse tests of works with different diameters were performed for several gripping forces and gripping lengths in which the bending stiffness, logarithmic decrement and dynamic compliance of the chuck-work system were measured. The investigation showed that the bending stiffness varies with the direction of the bending load acting a jaw. The bending stiffness tends to decrease with the gripping force because of the increase of the clearance between the top of a jaw and a work. The greater the gripping force or the smaller the work diameter in comparison with the gripping length, the lower the damping efficiency of the system and the greater the dynamic compliance. Therefore, small values of the gripping force should be chosen for the works used in the experiment.

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The objective of our study is to propose a methodology to establish the CAE system for assisting product developments. In general, for new product development designs, the design objects are frequently redesigned on the basis of experimental results. This paper show a method to establish the CAE system, which possesses an engineering model of a design object in the model database, and refines the model on the basis of experimental results. We have utilized the blackboard inference model to infer the model refinement and the redesign countermeasure. The validity of the proposed CAE system has been verified by developing an active magnetic bearing for a turbomolecular pump.

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Actual design ways are multiobjective design satisfactions with heterogeneous objectivd functions such as performance and cost, with dimensional design variables such as part size and distance. To materialize the actual designs in computer-aided design, this paper presents a new method which determines structural dimensions (design variables) in order to make all objective functions accomplish their respective functions. Heterogeneous objective functions can be described in the same form (newly introduced attainability), which apparently indicates the satisfied functions by a positive sign or zero. The sensitivity coefficient matrix provides the most Successful Variables which improve a minimum, as well as a negative, attainability to positive or zero, and simultaneously keep all positive attainabilities positive or zero. Values of the variables are revised iteratively for this purpose. In an agricultural transmission gear design, the method produced remarkable and practicable results in short CPU time.

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A discussion is presented as a contributive memorandum on the future development of the theory of the Duffing equation. The most reasonable arrangement and expression of the exact solutions for the free vibration are proposed, in which three cases are assumed according to the combination of system parameters; i. e., (a) #soft spring system, (b) #generalized hard spring (proper hard, single-term-cubic, and snap-through full-swing mode), and (c) #snap-through spring half-swing mode. For the case of forced vibration, a new formulation of the fundamental equation is proposed, to gain the advantage of a smooth transition between the case of the single-term-cubic spring (a singular case) and the hard or the snap-through spring case, avoiding the difficulty of division by zero. The new formula also has the merit of reducing a parameter in the range from 0 to 1, which expresses all possible magnitudes of excitation.

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