A new technique is presented for analyzing the 3-D wave fields in anisotropic laminated plates excited by time-harmonic point loads. The finite element technique is used to produce a set of approximate partial differential equations. This set of differential equations is then changed into a set of algebraic equations using a 2-D Fourier transform. The resulting set of algebraic equations is solved by a modal expansion method. The 2-D inverse Fourier integration is first carried out analytically in one direction using Cauchy's theorem. An adaptive quadrature scheme is then used to evaluate the integration in the other direction. The present technique is very efficient in computing the 3-D response of anisotropic laminates in the frequency domain, since only 1-D integration needs to be carried out numerically. Numerical examples are presented to demonstrate the efficiency of this technique.

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In order to investigate various nonlinear response characteristics, including buckling, of thin cylindrical shells under vertical and horizontal seismic motion, pseudodynamic experiments and nonlinear response simulation analysis are performed. It is confirmed that buckling is caused mainly by horizontal seismic loads, and that vertical seismic loads reduce the lateral load-carrying capacity of cylinders and amplify the response displacement for a given horizontal seismic load. To evaluate the amplification of nonlinear horizontal responses due to vertical input motions, we define a response amplification factor, which is calculated from the floor response spectra of seismic waves.

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This paper describes new cuts for torsional mode quartz crystal resonators, which are called "TT(Y)-cut". The object of this paper is to propose new cuts for torsional quartz crystal resonators with a zero temperature coefficient and to clarify their frequency constants, frequency temperature behavior and electrical equivalent circuit parameters. First, torsional rigidity C_t is derived from stress function ψ obtained by solving approximately a partial differential equation by Galerkin's method. Next, from the frequency equation numerous relationships where the first order temperature coefficient a reaches zero exist between thickness-to-width ratio Rzy and cut angle (ψ, θ). Especially, the second order temperature coefficient β has a small value of -1.25×10^-8/°C², whose absolute value is approximately one third of the flexural mode quartz crystal resonators. Finally, it is shown that torsional quartz crystal resonators of tuning fork-type are successfully obtained with a small R₁ of 3.5 to 4.6 kΩ and a large Q value of 241000 to 272000 in a frequency range of about 300 to 600 kHz.

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This paper deals with an application of Electro-Rheological(ER) fluid to a squeeze film damper which enables a flexible rotor to reduce whirling amplitude by adjusting the damping property at each rotating speed. An experimental small scale model composed of a flexible shaft and a controllable ER squeeze film damper was constructed and its performance was studied under various electric field strengths. The ER fluid used in the present experiment was a colloidal suspension of silica powder in mineral oil. Furthermore, a theoretical approach to the performance of ER squeeze film damper was made in which the short bearing approximation of a journal bearing with Bingham plastic fluid was introduced. It is shown that the natural frequencies of a flexible shaft was increased continuously as the applied electric field was strengthened in the experiment, and that the simplified theory introduced in this paper shows good agreement with the present experimental results.

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In this paper, we derive the shear coefficient K for trigonal crystals of rectangular cross section in Timoshenko's beam theory of three dimensional (3-D) elasticity. The theoretical result gives K as a function of the transformed elastic stiffness constants c₂2, c₄4, c₆6. For an isotropic material it agrees completely with that derived by G. R. Cowper. In addition, values of K versus cut angle for quartz crystal, lithium tantalate, and lithium niobate which belong to the trigonal system are calculated, so that K has a value of 0.796-0.867 for quartz crystal, 0.834- 0.857 for lithium tantalate, and 0.831-0.863 for lithium niobate, when Z-plates of the crystals are rotated with a cut angle θof 0-180°about the x-axis. The values of K are then compared with those for isotropic materials obtained by other authors.

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The purpose of this study is to analyze a simultaneous vibration control method of structures. The analyses are performed under the following assumptions: each structure is composed of a mass and spring and vibrates in a one-degree-of-freedom mode, and a vibration input is applied to the base of the structure. Here, the vibration model is composed of two structures connected by one damper and one spring in parallel. From the analyses, it was clarified that the theory of P, Q is useful as a method of optimum adjustment of this vibration control model. In addition, the optimum design procedure is described, the optimum values of tuning and damping parameters of this model are specified in graphical form, and the effectiveness of this method in reducing the transmissibility during resonance is shown to be considerably greater than that of the method connecting two structures by only a damper.

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We design a machine that adapts to the user considering his/her personal differences. This paper deals with the interactive relationship between both user and machine as they try to adapt to each other. We call this relationship interactive adaptation. The interactive adaptation interface (IAI/F) is an intelligent interface that is designed based on interactive adaptation. This interface changes the characteristics of the system according to the given task, considering the state of the user, such as skill level, technique, characteristics, and physical conditions. We propose a design and a method for realization of IAI/F, based on recursive fuzzy reasoning. As an application example, we present a virtual-reality simulation game and apply the proposed IAI/F based on the user's performance and the galvanic skin reflex (G.S.R.). We present the system considering interactive adaptation, and show some experimental results and statistical evaluation results to discuss its effectiveness.

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In this paper we discuss the vibration control of a flexible structure which possesses transverse-torsional coupled vibration modes using two active dynamic vibration absorbers. The H^∞ control theory is adopted to obtain an output-feedback robust controller by which structural vibrations in two lower vibration modes are reduced without spillover. The statements of the control object are organized into the generalized plant, that is, robust stabilization and sensitivity reduction. A method of synthesis of the controller is presented in which balancing of control inputs is taken into consideration. In numerical analysis and control experiments, it is confirmed that the controller achieves considerably high performance with robust stability.

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A single-rod cylinder servo system driving a discontinuous load is a 4th-order nonlinear system. It can be simplified as a time-varying 1st-order system for typical low frequency applications. The time-varying parameters of such a system conceal the discontinuous loading effect, uncertainties and transient behavior of a single-rod cylinder and servovalve. To overcome these difficulties, the parameter identification process requires the characteristics of exponential convergence and unbiased parameter estimation. Here, the parameter identification process incorporates the 1st-order ARMAX model with PEDF algorithm. Experiments indicate quantatively that this identification process is superior and more adaptive than high-order ARMA models with RLS algorithm.

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A two-actuator electrohydraulic bending machine is a typical MIMO system, where the level control function is degraded by the interior structural difference between the two actuators and also by the hydraulic drive interaction. The conventional self-tuning control and decoupling method are too complicated and time-consuming, and are not suitable for this system. Based upon our previous studies, this system can be simplified as two individual sets of servo-control actuating system, which is simulated as a 1st-order ARMAX model and its coupling interactions between actuators are treated as a disturbance term of the ARMAX model. Then, two sets of implicit self-tuning controller and a level control regulator are designed for servo-tracking and level control. This proposed control scheme not only reduces the number of parameter estimations significantly, but also yields the effect of dither in order to overcome the drawbacks of servovalve stickiness and mechanical frictions. Finally, the experimental results indicate its satisfactory performance and prove its superior decoupling ability and disturbance rejection.

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In this paper, we describe the behavioral characteristics of a nonlinear oscillator derived from gear-meshing vibration, which exhibits various successive bifurcations ending in chaos. There are two types of sudden change from a chaotic to a periodic attractor, one of which is called "hysteresis". In a period-doubling bifurcation, a heteroclinic connection between the outset of an inversely unstable fixed point of period 2n and the inset of an inversely unstable fixed point of period n is necessary to generate an n-band chaotic attractor. If a directly unstable fixed point exists in the vicinity of any band attractor and the attractor collides with the inset of the directly unstable fixed point, the attractor expands due to an "interior catastrophe", and transforms into a one-band attractor. In the bifurcation diagram, periodic subharmonic oscillations appear discontinuously as "windows" belonging to the same "family". These "families" are divided into two types : type-I, in which fold bifurcation occurs repeatedly, and type-II, in which fold bifurcation occurs only at both ends of the solution curve. Depending upon whether or not both of the chaotic attractors exist in the same area of the phase plane, either before or after the bifurcation, the discontinuous bifurcation of the chaotic attractor is referred to as an "interior catastrophe" or "hysteresis", respectively.

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An approach is introduced to analyze the robust stability of linear digital control systems under both finite wordlength effects and linear time-varying parameter perturbations. Digital controllers are realized with floating-point arithmetic. The robust stability criterion (sufficient condition) presented in this paper can be used to obtain the stability bound on a linear time-varying uncertainty matrix due to the combination of parameter perturbations, feedback gain quantization error and computational roundoff errors. This bound provides a quantitative measure for control engineers to design an actual closed-loop digital control system with robustness. An example is given to illustrate the application of the proposed robust stability criterion.

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Digital servo systems for small magnetic disk drives with high track-densities must overcome poor control performance caused by mechanical gain variations of both the position detectors and the voice coil motor in each disk drive. This paper presents a method for adaptive control of the digital track following servo system. A reduced model for the magnetic disk drive plant is introduced that includes actuator dynamics and a time-delay element for both computation time-delay and several notch filters. A design procedure for adaptive control of the mechanical gain estimator is based on an estimator model consisting of the reduced plant model and uses the recursive least-squares algorithm with low-pass filters. This adaptive control method provides good control and is implemented using a digital signal processor.

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This paper presents a method for implementing neural control systems to control mechanical systems. The neural control systems are designed focusing on the difference in the neural network learning speed between an adaptive and a learning scheme, so the control systems are constructed with both an adaptive neural identifier and a learning neural controller. To ensure both robustness and stability at the beginning of learning, the neural control systems incorporate a conventional feedback controller. The use of neural control systems to control a tunneling machine, used to construct underground conduits for telecommunication cables, is numerically simulated to investigate the proposed controller's capability and characteristics. A simple model of the tunneling machine, which is used as the controlled plant, is derived by analyzing the force acting on the tunneling machine from the surrounding ground. Simulation results confirm the feasibility of the neural control systems and show that the direction of the tunneling machine can be controlled by using the NN learning ability.

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Based on matrix algebra manipulations, we derive the kinematic closed-form solutions of general-type Sarrus mechanism and identify the limit positions through direct differentiation of a matrix closure equation. Moreover, we show that the coupler curve and coupler link have straight-line motions whose equations are established as well. In practical applications, the dimensional synthesis of this mechanism for function, path and motion generators is accomplished by the optimization technique. Finally, three numerical examples are given and their results are verified through computer simulations.

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The present paper deals with the boundary element analysis of transient and nonlinear motion of shallow liquid in a two-dimensional rectangular tank subjected to forced horizontal oscillations. The problem is formulated mathematically with a velocity potential. The basic equations including nonlinear boundary conditions are discretized in space by the boundary element method and in time by a forward-time Taylor series. Due to the shallowness of the contained liquid, the vertical dimension of the solution domain becomes much smaller than the horizontal one. Then, the normalization of the solution domain is carried out : the physical domain is transformed into the normalized domain with unit tank length and unit mean liquid depth. The boundary element method is applied for the solution of the equations thus transformed. The numerical results are compared with available experimental data, and good agreement is obtained.

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In a nonstationary signal analysis, it has been clarified that the discrete Wigner distribution, WD, is the most suitable distribution. The use of the WD is, however, often complicated by the occurrence of interference terms. Thus, we proposed a modified WD, called the RID (reduced interference distribution), and verified that the RID could markedly suppress the occurrence of interference terms in both the auto-and the cross-WD. In this study, we developed another method which makes use of a block adaptive filter to eliminate interference terms and evaluate them quantitatively. In this method, the least mean square, LMS, algorithm is applied in the frequency domain. Simulated signals of a chirp type and an acoustic signal of a concert hall are analyzed using spectrograms, WD, RID and the new method. From comparisons among the results, it is concluded that the best result can be obtained using the new method proposed in this study.

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For a path control problem, we previously proposed a preview control system which has a superficial evaluation term in its performance index, and showed that the system is not effective for application to the following two cases. The first is when the tracking position lies along the velocity vector of the desired path. The second is when the desired path does not change. In both cases, the term becomes zero, and the path error becomes large. To solve the problem caused by the first case, we previously proposed the introduction of an auxiliary superficial evaluation term into the performance index. In this paper, to solve the problem caused by the second case, we propose the introduction of a virtual axis. The synthesis method for the new path control system is presented. To evaluate the effectiveness of the system, simulation studies are carried out. The simulation results show that the path tracking ability is markedly improved.

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An optical scanning system for reading and recording large images with 1 m width has been developed. The laser beam is deflected by an acousto-optical deflector (AOD) and the optical head on which the imaging lens is mounted is moved at high speed in a direction perpendicular to the optical scanning axis. A mechanical feed parallel to the optical scanning axis is added in order to scan the entire surface of the image. To maximize the scanning speed, the laser beam is separated into two beams and two data sets are read and recorded simultaneously. Variations in the optical length caused by the movement of the optical head must be considered in the design of the optics. A cylindrical lens and a ROM for maintaining a constant-frequency sweeping speed are necessary in order to compensate for the cylindrical effect of the AOD. Since the light intensity is too low for use of a CCD to be effective, it is necessary to use a photomultiplier as the scanner.

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In this paper we present a method for synthesizing planar multilink mechanisms which can generate desired planar paths. In previous studies, various optimization methods were applied to synthesize path-generation planar multilink mechanisms. The techniques used, however, were often cumbersome and computationally costly to apply. These problems are mainly due to the high nonlinearity of synthesis mechanisms and the existence of many local solutions. Genetic algorithms have recently been noted as a method for solving the problems described above. Therefore, a new method for synthesizing planar multilink mechanisms is presented based on genetic algorithms. The present method require no initial mechanisms and can Search for multiple appropriate mechanisms simultaneously. Furthermore, it can be applied to various synthesis problems. We focus on a closed curve adapting synthesis. As an example, configurations of 4-bar and 6-bar planar mechanisms are determined in a practical application.

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In this work, we investigate the possibility of biological machining by bacteria as a new technique for metal removal. Some kinds of chemolithotrophic bacteria gain energy from inorganic matter and fix carbon dioxide from the air. One of them, the bacterium Thiobacillus ferrooxidans, "eats" metals. Machining of grooves on pure iron and pure copper by Thiobacillus ferrooxidans is experimentally investigated. The experimental analysis showed that biomachining was possible, since the depth of the grooves generated on the workpiece increased almost linearly with the machining time. Furthermore, electric-field-assisted biomachining proved to be even more effective, because the removed rate became much higher under an electric field.

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For high speed machining with rotating tools and a new type surface finishing with non-rotating cutting tools; it is necessary to develop a CAM system that can generate accurate CL data with high speed and high reliability. In order to extend CAM functions, a unified algorithm for CL data generation was developed that can be applied for both tools. This unified algorithm is based on simulating the servo data generation method of a copy milling machine. The tool path is defined in a calculation of contact points between the model and the stylus head. Therefore, preceding processes of offset surface generation and tool interference check can be abbreviated. The developed system has the following four tool path modes; (1) the scanning line, (2) the contour line, (3) the 3 D profile, and (4) the contour line roughing. Tool path simulations and cutting tests show that the developed system can generate CL data with high accuracy and reliability.

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In this paper we describe "the form-shaping system theory" using tool and contour grinding simulations. The form-shaping system enables the simulation of the form-shaping process, and takes into account machine tool error, facilitating quantitative investigation of the influence of this error on the machining accuracy. The computer simulations and the actual grinding tests reveal the practicality of the system for analysis of the machining accuracy.

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The finite element method has been successfully employed to investigate thermal behaviour in metal machining. The present paper concentrates on cutting temperature which is affected by the thermophysical properties of both work and tool materials, and the coefficient of heat transfer of a coolant. The use of a high-thermal-conductivity tool such as diamond is more effective in reducing the rake temperature than the use of a coolant. This tendency becomes more obvious when a low-thermal-conductivity material such as titanium alloy is machined. However, the cutting edge of a high-thermal-conductivity tool is subjected to an increased mechanical load due to a temperature drop in the work and chip materials; the increase of flow stress requires an increase in the cutting energy in the deformation zone. The predicted rake temperature, based on the shear plane cutting model, is in fairly good agreement with the experiment, though a better result is given by the finite element machining simulation in conjunction with precise material properties.

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An inverse analysis approach using the finite element method is proposed to determine the energy balance or the energies flowing into a tool, workpiece and chip per unit volume of material removed in two-dimensional machining. Once the energy flow rates are obtained, a three-dimensional temperature distribution for complicated tools such as an end mill can be analysed easily and efficiently. The method proposed is employed to clarify the effect of thermophysical properties on the energy balance. The energy flowing into the tool is most enhanced when a low-thermal-conductivity workpiece is machined by a high-thermal-conductivity tool with a coolant; wet turning of titanium alloy by a diamond tool is a typical case. It is found that temperature change of a carbide square end mill ranges from 400 to 800°C in titanium machining at a cutting speed of 314 m/min because of a low energy flow rate into the tool of around 0.04 and the action of a coolant. The suitability of the present method is confirmed by comparison with the Loewen-Shaw model as well as by temperature measurement.

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This paper deals with the development of a method for ball screw generation. The method is based on a generation process that uses a standard-shaped grinding wheel, instead of a form-grinding process with a form-dressed grinding wheel, and requires no extensive form-dressing process. With the newly developed thread-generation system, the wheel axis is set three-dimensionally at the computed optimum angle of inclination, based on the tilt and swivel angle components of the planned ball screw and grinding wheel. The optimum angle of inclination that gives the minimum geometrical error is determined by a numerical simulation of the generation process with the aid of a computer. The suggested ball screw generation method is shown to be effective by computer simulations with several geometrical shapes of grinding wheels and generation experiments.

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