In many shell and tube heat exchangers such as steam generators, baffle plates are located at appropriate intervals to support the heat transfer tubes. In the heat exchangers, the secondary coolant streams through the channels such as the flow hole nozzles of the baffle plates in the form of jets, and flows in parallel with the tube bundle. This turbulence induces vibrations which could cause fretting wear and fatigue of the tubes. In this paper, basic characteristics of tube vibration were experimentally investigated in air-water two phase flow to evaluate the jet effect on the relationships between hydrodynamic mass, damping ratio, and excitation force on a vibrating tube and void fractions.

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In this paper, two types of techniques for the prediction of radiated sound pressure due to vibration of a structure and the optimal design of sensor configuration is studied. The prediction performance of wave-number sensing technique in far-field area is compared with traditional Rayleigh's integral method. For a coupled plate, the prediction performance of far-field sound is verified using wave-number components, which are predicted by the vibration response of plate. In additon, distributed sensor that can not be allowed in Rayleigh's integral method is proposed to replace point sensor. Experimental implementation verified the prediction accuracy of far-field sound radiation by the wave-number sensing technique. Prediction results from the new technique are as good as those from Rayleigh's integral method, and with the distributed sensors, more reduced computation time is expected. The organization of the optimal sensor is newly designed for the accurate and efficient estimation of the sound radiation. To predict the radiated sound using the effcient configuration of structural sensors, composed vibration response is determined considering acoustic power contribution, and size and locatio of sensors are chosen. Four types of sensor configuration are suggested, simulated and compared.

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This paper deals with a vibration control experiment using an iterative identification and control design method. The purpose of this investigation is to suppress the natural vibrations of structures. The experimental device has three links behaves as a vibration system. The feature of this device is that the control system is not sensor / actuator collocated for practical use of an air jet actuator. In order to suppress natural vibrations, LQG control and Tb₂ control are applied to the model, which is identified iteratively on the basis of the closed-loop experimental input / output data.The achieved performance is improved, moreover, by a change for the better of the designed control performance in each iteration. In control experiments, initial displacement responses and resonance signal responses are examined. It is shown that the iterative design method is useful to design vibration controlled systems and can perform better on suppressing the natural vibrations and disturbances than non-iterative design methods.

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In this paper we report the characteristics of force moment about the center of mass (COM) of a human body during level walking at a steady pace, using two large force plates by which the three-dimensional floor reaction force components can be measured. The displacements of COM in the three directions are obtained from the Fourier series of the reaction force components by double integration. The following results are obtained : although the three-dimensional reaction force components are large, the moment of force about the COM becomes very small, which suggests that a human walks producing as small a moment as possible about the COM of his / her body. In other words, only a negligible rotation about the COM occurs ; the magnitude of the external moment applied at the sole is remarked in the moment of force about the vertical axis.

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Integrated structure / control design of a one-link flexible robot arm is investigated in this paper. The arm consists of a tip mass, a flexible link and a hub and is driven by the hub motor to reach pre-defined tip position and suppress residual flexural vibrations. The arm is modeled using finite element method and the cross-sectional dimensions of the beam elements are used as structural design variables. A sliding mode controller and a linear stabilizer are used to regulate the arm position. The structural and control parameters are optimized simultaneously using genetic algorithm and the simulation results show the advantages of the new design method : faster regulation and less weight for the optimized arm than a uniform arm.

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We present a model in the frequency domain of the dynamic characteristics of magnetic actuators with a C-shaped stator of solid iron core without leakage flux. First, with eddy current effects, simple approximations are proposed with half-power of frequency and a complex number to a theoretical magnetic reluctance based on a two-dimensional analysis. Magnetic hysteresis effects are considered in a simple way on the assumptions that the static hysteresis loop is approximated by an elliptical function and applicable to the dynamics in its original form. The dynamic characteristics of the incremetal magnetic flux and coil-current are obtained through the magnetic circuit theory with the variation of a working air-gap. To check the model, the numerical frequency responses are compared with the experimental results when the working air-gap is fixed.

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The study investigates the feasibility of pulsed laser seam welding of zinc coated steel sheets in lap configuration using Lumonics JK 701 Nd : YAG laser. This is a useful and beneficial joining technique for the automotive industry in the assembly lines. Laser seam welds were produced in 0.7 mm thick electro-galvanized steel sheets in the lap-joint configuration with rectangular power pulses. A wide range of process parameters is identified. These includes average peak power density (APPD), mean laser power, traverse speeds, and pulse duration, etc. To optimize the welding process, the effects of these parameters on weld quality are thus systematically investigated. The experimental study suggests that APPD is the most critical factor in governing pulsed laser seam welding application. It is followed by average power and travel speed. As such, the processing map for APPD effects is developed as a guide for effective cotrol and execution of welding application. Accordingly, the pulsed Nd : YAG laser seam welding process can be further optimised by proper choices of APPDs, mean powers, and traverse speeds for producing the best quality welds. That is, welds with no porosity inside the fusion zone.

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This paper presents a theoretical research on the integral sliding control technology for linear time-invariant systems encountering disturbace matched to part of the control inputs. Only part of the control inputs is designed by the sliding-mode theory to eliminate the disturbance. Besides, based on the pole-assignment method the design of integral sliding vector becomes simple and straightforward. A numeric example is finally used to demonstrate the success of the developed controller.

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Various advanced ultrasonic flaw classification approaches have been proposed for the determination of flaw types in weldments. Among them, ultrasonic pattern recognition approaches have seemed to be most promising, and thus extensive investigations have been carried out in the ultrasonic nondestructive evaluation community. In spite of these extensive endeavors, these approaches have not been widely used in the current industrial field applications due to some critical barriers in cost, time and reliability. To reduce such barriers, here we propose an intelligent system approach realized by the novel combination of following four ingredients such as 1) development of a PC-based real-time ultrasonic testing system, 2) construction of an abundant experimental database of ultrasonic flaw signals in weldments, 3) establishment of an invariant ultrasonic pattern recognition algorithm by use of newly proposed normalized features, and finally 4) implementation of this invariant algorithm in the form of intelligent flaw classification software. In this paper we address in detail the proposed approach including its four ingredients and its capability of making the industrial field application of ultrasonic pattern recognition approaches low cost, rapid and reliable in their performance. The performance of this approach has been investigated with abundant ultrasonic signals captured from various flaws in weldments with variation in the operational variables of the ultrasonic testing. Especially, we have examined the capability of this approach for reducing the effect of the operational variables on the classification performance in terms of the class-conditional probability density functions and correct accept rates. The reasonable and consistent performances obtained in this work demonstrate the high potential of this approach to serve as a convenient and robust tool for many real world flaw classification problems in weldments.

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A design method for active suspension systems of vehicles is proposed based on the decentralized variable structure controller (DVSC) and a 7-degree-of-freedom fullcar model. Its nominal stability and stability robustness to parameter variations are assured through stability analysis. The performance of the DVSC is compared with that of a LQR controller in computer simulations. From the simulations, it is found that active suspensions with the DVSC redue the acceleration of the sprung mass in the heaving, rolling, and pitching directions when the car is driven on a normal road or through an asymmetric bump. The suspension stroke and road holding capability are also compared under the assumption of equal power consumption.

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Based on geometrical intuition and computer graphics, we present the formation of two kinds of Schatz six-revolute mechanisms and two types of algebraic surfaces on which the corresponding reciprocal screw axes lie under any possible configurations. Then, we derive the general kinematic closed-form solutions and show the absence of stationary configuration of both mechanisms using four-by-four matrix and differential algebra. Moreover, the parametric formulations of coupler-point motion provide a complete higher-order analysis of the coupler curve. In practical application, this mechanism is further used for the dimensional synthesis, path and motion generation synthesis, by the nonlinear programming optimization method. At last, two numerical examples are taken to illustrate the design algorithm.

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This paper discusses the capability of phase angled counterweights to improve the dynamic characteristics of a radially compliant scroll compressors. Based on force and moment balances on crankshaft and compressor frame, mathematical formulation of shaft bearing loads, unbalance force and moment acting on the frame has been made in terms of counterweights design parameters such as masses and phase angles of the upper and lower counterweights. Any two of crankshaft main bearing load, sub bearing load, unbalanced body force, and overturning moment can be controlled by the counterweights design parameters.

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The stability robustness of linear time-variant systems with both time-varying structured and unstructured perturbations is investigated by using the Lyapunov approach and some essential properties of matrix measures. Some new sufficient conditions are proposed for ensuring the linear time-variant systems with both time-varying structured and unstructured perturbations to be uniformly asymptotically stable. For the case that the linear time-variant system only subjects to time-varying structured perturbations, by mathematical analysis, the presented sufficient conditions are proved to be less conservative than the existing ones reported in the literature. The result only for structured independent time-varying perturbations case is also extended to the stability analysis of time-variant interval systems.

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The cross-flow fan system of the split type room air-conditioners often generates the discrete noise component that is called the Blade Passing Frequency tone. It has been known that the BPF tone is generated due to the fluctuating pressure field of the aerodynamic interaction between the rotating fan blades and the stationary stabilizer (or cut-off). Several methods have been invented to reduce this BPF noise. One of the promising schemes is to skew the stabilizer with respect to the fan blade span, which shifts the phase of the pressure fluctuations along the fan span. In this study some experiments have been carried out to investigate influences on the performance and the noise characteristics of the various skew shapes of the stabilizer with the experimental rig which simulates the indoor unit of the split type room air-conditioners. Also a guide is proposed to develop an optimal skew shape of the stabilizer, which dose not significantly impede the aerodynamic performance and has a better noise characteristics.

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Synchronizing control of a four-cylinder electrohydraulic servosystem is considered in this paper. For simplification of design, the system is separated into four subsystems, which track the same output signal of a reference model. The interaction forces among the four cylinders are considered as disturbance forces and the time delay control scheme is used here to estimate the disturbance force and and unknown system dynamics. For reducing the sensor noise controller design, the observed state variables are used in place of the numerical differentiated ones. The feasibility of the proposed control strategies is verified via experimental studies in this paper and the stability of this closed-loop system is proved in Part II.

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In this paper, a multiple data dependent systems (MDDS) method is proposed to analyse the localised variation of cutting dynamics in single point diamond turning (SPDT). The metal cutting dynamics are characterised by the natural frequency, the damping ratio, and the relative contribution of the central wavelength components which make up the roughness profiles at a finite number of radial sections of the workpiece. The characteristics of these wavelength componets are correlated to different surface generation mechanisms. A series of cutting tests was carried out with different cutting conditions and materials being cut. Experimental results indicate that the cutting dynamics are dominated by the relative tool-work vibration and the swelling of the work materials. The contribution anb the natural frequency of the tool-work vibration components are found to vary with the crystallographic orientation of the workpiece. These localised variation of cutting dynamics are shown to be caused by materials induced vibration which is inherent in the cutting system for a work material.

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In this paper, group robots which can adaptively form a mechanical structure are described. The group robots consist of identical cellular robots. Each cellular robot has the identical mechanical structure and autonomous behavior. In the situation considered in this study, a mobile object must cross over from one cliff to another in the absence of a bridge. The mission of the group robots is to form a mechanical bridge-like structure which is governed by the movement of the object. This paper focuses on the mechanical specifications required for the cellular robots for execution of the mission. We pointed out that three mechanical parameters for the sensing stress of the cellular robot are essential for formation of the structure. The structure formation process was examined by computer simulations for discussing the effects of the mechanical parameters.

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This study deals with autonomous distributed robots that are able to adaptively construct a structure in response to a loading condition. The simulation consists of identical components (cellular robots). Each cellular robot has functions for sensing, communication and motion. In this paper, we discuss the following situation. There is a gap on the ground. A moving load lies at one side but cannot reach the opposite side. The mission of the cellular robots is to help the moving load pass over the gap by forming a bridge-like mechanical structure. After finishing the mission, they must return to their original place. We examined the information processing required of the cellular robots to execute the mission and proposed algorithms based on local rules. Using these algorithms, we simulated the group behavior of the cellular robots on a computer and demonstrated validity.

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The existing teleoperation methods, which verify the command only as a single command not as a series of commands, have poor operability under communication time delay. This is because the inappropriate operation can only be stopped just before the execution and the following restarting operation becomes very difficult. This report suggests a new on-line teleoperation method equipped with the additional delay mechanism, which adds some additional time delay to communication time delay to maintain a command buffer. Every verfied command is temporarily stored in this buffer before transmission and, when a wrong command is generated later, part of the commands or all the commands in the buffer are automatically reedited to make a new series of commands which smoothly avoid the wrong operation. The operation continues smoothly from the last command point that was left after the reediting.

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A feedback-error-learning neural network approach to on-line learning control and real time implementation for a flexible micro-actuator is presented. The flexible micro-actuator is made of a bimorphic piezo-electric high-polymer material (Poly Vinylidene Fluoride). The control scheme consists of a feedforward neural network controller and a fixed-gain feedback controller. This neural network controller is trained so as to make the output of the feedback controller zero. In the process, the neural network learns the inverse dynamics of the system. We make some comparisons between using PID and LQG controllers with this neural network controller. Experimental and numerical results for the tracking control of a piezopolymer actuator are presented and they show that the feedback-error-learning neural network is effective in accurately tracking a reference signal.

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A self-acting air bearing draws surrounding air into the gap between the stator and rotor, and does not need any air pressurizing equipment. This type of air bearing has wide potential application. In this study, parametric and interaction effects on the bearing performance are investigated experimentally and optimal conditions are found for self-acting spiral grooved semi-spherical air bearings using the Taguchi method. The three design parameters are clearance, groove depth and out-of-sphericity. The performance factors are axial runout and axial impulse stiffness. Investigation of the effects of the design parameters shows that high performance is achieved generally for a small clearance. Optimal conditions are found to depend on a performance factor.

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The study deals with cutting of metal mold for a tiny Fresnel lens which is composed of circular micro grooves. Conventional methods such as photolithography and cutting by a lathe often lead to the burr generation due to a reduction of cutting speed, especially at the center of lens, and to low surface quality such as step-like cross-section of groove by photolithogrphy. The employment of a rotational diamond cutting tool is expected to eliminate the above problems. Thus, a workpiece of Fresnel Lens is set on the main spindle of a lathe-type ultraprecision milling machine, which has the positioning accuracy of 1 nm. The diamond cutting tool is rotated by a high speed air turbine spindle. According to the cutting experiment, no burr was found at the edge of grooves, and the surface roughness of a slope in the groove was 80 nm (R_max). The cross section of lens groove is slightly curved due to the unique way of cutting, which made a profile of lens get closer to the ideal one.

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The study deals with the manufacture of microgrooves with sharp edges and smooth oblique and / or curved surfaces by means of an ultraprecision milling machine and single crystal diamond endmills. Fine microgrooves are key components to fabricate mivrograting, micrograting lens and so on. Conventional groove fabrication methods such as etching and lithography are difficult to make grooves without burr. The new machining method proposed in the study allows to produce V-shaped grooves of 100 μm in pitch with enough shape accuracy and surface roughness of 48 nm (P-V value). The method also makes it possible to form the microgroove of 1 μm in pitch with sharp edge and without burr. In addition, the method is experimentally found effective to produce R-shaped groove and trapozoid-shaped one without burr.

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The designer's intention is the essence of design. But the geometric information is the only one that we handle in the conventional CAD system. In this paper, we propose the description model of designers' intention that might be helpful to reduce the troubllesome communications among the designers. The designers' intention is described as the correlation using the required funtions, the binding conditions, the technical information, the connotational assignments and the geometric information. The required functions are represented by a tree structure to show the sequence of designers' consideration. The lowest function is assigned to the functional elements that are selected from the geometric information according to the connotational assignments. Additionally, the binding conditions and the technical information are related to the functional elements. The effective usage of designers' intention model is verified under the redesign process. It shows that the redesign is processed successfully using the designers' intention.

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With the increasing demands for higher accuracy and higher productivity in the manufacturing environment, ultraprecision table positioning technology of nanometer order is urgently required. In order to meet these requirements, it is necessary and indispensable to develop the ultraprecision table systems of noncontact type, which is constructed from an aerostatic guideway and a linear motor. However, such a table system of noncontact type has low performances in the positioning stability and the disturbance response, because of friction free and low damping capacity in the guideway. Inthis study, therefore, a linear motor-driven ultraprecision aerostatic table system equipped with electrorheological fluid (ERF) units has been developed. Furthermore, it has been verified that the developed ERF units are effective and applicable to simultaneously achieve quick-response and nanometer positioning accuracy.

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Innovations for a database thesaurus must be vigorously pursued in the next decade. Our project was intially intended to develop and artificial intelligence in forward inference for database query systems, but later it evolved to a thesaurus system which is equipped with a search engine composed of a framed knowledge base. This objective has been accomplished for a database of FEM (Finite-Element Method) literature accompanied by their mesh data, of which graphical output is viewable at a human interface. When we were analyzing maneuvers of the search engine among the network of keyword thesauri, the findings led us to to try applying this engine for a very similar tracking of a network of FEM meshes in view of its potential ability for mesh pattern recognition. Furthermore, the algorithm used to infer keywords in the thesaurus is adapted to recognize shapes of FEM meshes used in the analysis. These meshes are kept in a general-purpose RIQS database, where one might be able to find a particular mesh, the configuration of which might be similar to his own, or a mesh belonging to a specific classification. By replacing the thesaurus topology with a network of FEM meshes, the inference engine can retrieve elements or mesh contours by comparing them based on similarities or dissimilarities. The efficiency in terms of retrieving mesh objects has been measured by applying real FEM data in RIQS database.

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In this paper, an algorithm of filling N-sided patch with a trimmed bipolynomial parametric surface is proposed. First, a virtual boundary is used and the N-sided curves are treated as some discrete points. Then using a algorithm of fitting arbitrary scattered points to parametric surface, a smoothly large piece of surface can be generated to approximate the N-sided curves within a given tolerance. In the end, the N-sided surface is produced by trim operation. Using this algorithm, the shape of the initial produced surface can be modified in an interactive way by pulling some points or curves on it. In order to approximate G¹ continuity with adjacent surfaces, Levenberg-Marquardt optimal method is used for final refinement. Several examples are given out to show the effectiveness of the proposed algorithm.

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It is to an advantage of manufacturers to forecast the next generation technology as precisely as possible in this survival and competition age. The most popular way follows the trend of technology of interest and the result of fundamental research. While reliable, this approach ca predict only the short term future and cannot consider hidden, heuristic development by competitors, because the information concerned is rather limited in a certain organization. On the other hand, patent information is much more reliable and feasible as inventions are generated from fundamental research conducted all over the world. The present paper makes it clear that patent information can yield fruitful results such as a predicted year of commercialization for a particular technology, if the patent information is properly processed. A method for grouping the technology field, summing up the patent information, and forecasting the year of realization of a specified technology is proposed and examined in the current paper.

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The objective of this study is to present the theory and asystematic performance evaluation procedure for the Spherical Cam-Oscillating Roller-Follower (SCORF) systems by introducing two new indices, namely, the lubrication and the undercutting indices. The dynamic characteristics of the SCORF systems are of great importance in association with the performance of system operations, and thus directly affecting the overal efficiency of the production machine in operation. By taking advantage of a spatial coordinate transformation and the theory of surface meshing contact, the kinematic motion in terms of meshing requirements are derived in vectorial form. The meshing characteristics of the system including the pattern of linear line contact, curvature interference avoidance, the relative sliding behavior between the cam and the roller, and the conditions for a dynamic oil film formation, are carefully examined. Two evaluation criteria, namely, the lubrication angle and the undercutting interference avoidance checking indices, are developed and used to validate the proposed approach. The performance of the SCORF mechanism and the associate design evaluation criteria developed in this paper is shown to be useful, practical and can be extended for the design and analysis of other spatial cam systems.

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Optimal task sequence planning using a simulated annealing technique is developed for a high speed assembly station comprised of two robots. In order to minimize the tact time, parts are assembled by dual robots on moving workpieces which are transferred by a precision conveyer. The sequence of operations by the dual robots is optimized to minimize the tact time while avoiding the geometric and dynamic interferences between the dual robots. The optimization problem is a type of traveling salesman problem, but is highly complicated because the target destinations for placing individual parts keep moving on the conveyer. The speed of the conveyer which carries the workpieces should be also optimized in order to maximize the throughput of the assembly system. The task sequence optimization problem is formulated together with the problem of determining the conveyer speed. An efficient algorithm for the sequence optimization is developed and solved by the simulated annealing.

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Monitoring of the cutting force signals in turning process has been well emphasized for unmanned machining. Although the cutting force can be directly measured by a tool dynamometer, direct sensing in factory environment is not feasible because of high cost and limitations in setup. In this paper two indirect cutting force estimation systems are developed based on the measured output power and on the calculated input power signals, respectively. These estimation systems consider the cutting force as a disturbance input to the spindle drive and estimate the cutting force based on the inverse dynamic model. The inverse dynamic model represents the dynamic relation between the cutting force, the motor torque and the motor power. The proposed estimation systems are realized on a CNC lathe and their estimation performance is evaluated experimentally.

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From the viewpoint of the eigenvalues locations of the multi-time-scale systems, we realize that the eigenvalues positions of the fast subsystems are far from the slow subsystem ones, and the uncertainty or parameter variation will move the eigenvalues of a nominal system away from the desired ones. Therefore, it is significant to guarantee that the eigenvalues of the perturbed system lie inside our desired regions as those of the nominal system. The multi-time-scale system under structured perturbation is considered in this paper. We present some sufficient conditions for the robustness measures of eigenvalues assignment in the specified regions. A design algorithm by the method of constraint optimization to design a robust decentralized controller to assign the eigenvalues of whole multi-time-scale system is also provided in this research. An illustration example is presented to show the applicabilityof our proposed theorems.

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