In the field of mechanical engineering, a large number of time delay systems are found. While the systems are operating, unstable vibrations often occur due to the time delay caused by viscoelastic deformation, plastic deformation, cutting, grinding, wear and so on. Such phenomena are well known as the chattering of machine tools and the pattern formation phenomena in contact rotating systems. In this report, the authors study the property of new stability analysis developed for unstable vibration in contact rotating systems and apply it to system with time delay of a half rotating period. As a typical example, the prevention method by changing structural design is formulated for two-and three-degree-of-freedom system. The validity of the present method is confirmed from the numerical computational results.

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Recently, the blade with friction damper has been used in the steam turbine and gas turbine to improve the blade reliability. In designing the damper blade, the vibration characteristics can be predicted by the analysis and the optimal damper shape is determined. As for the verification test of the damper blades, sometimes rainbow test, in which several kinds of damper blades are installed on the desk, is carried out to reduce the cost of test. It is probable that the vibration characteristics of each damper blade cannot be identified from the rainbow test because of the coupling effect through the disk and mistuning. In this paper, the bladed-disk systems of damper blades are represented by the equivalent spring mass system and the simulation of the rainbow test is carried out to clarify the condition from which the vibration characteristics of each blade is identified.

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This paper describes experimental and analytical study on the behavior of falling water sheets. Falling water sheet flowing over a dam sometimes oscillates. It in turn causes vibrations of paper sliding doors or windowpanes of houses in the neighborhood since its frequency is low. Experimental results shows that the frequency of water sheet is the same as that of the pressure in the air chamber. Water sheet vibration is closely related with an air chamber behind the water sheet. The vibration can be suppressed by putting a baffle at an appropriate height in an air chamber. Further, water sheet behavior is analyzed. Comparing experimental data with analytical ones we conclude that sheet vibration occurs around the conditions where the work done by the water sheet on the air chamber reaches a maximum.

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This paper deals with active boundary control termed ABC of a thin plate for the purpose of creating a completely vibration free state ; a quiet zone, on the designated area of a target structure. First, the principle of ABC once developed for a one-dimensional structure is expanded to a two-dimensional structure, thereby enabling the generation of a quiet zone on the desired location of a structure. Then, using a transfer matrix method, an ABC system is described, fundamental properties of the system being investigated. Furthermore, in addition to conventional boundary conditions, two more boundary conditions are found to be created using ABC. Moreover, it is found that ABC has the capability of producing a completely vibration-free state on the designated area. Finally, in an effort to verify the validity of ABC presented in the work, a numerical analysis as well as an experiment is conducted, demonstrating the capability of ABC.

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For chaotic vibrations involving dynamic through generated in a post-buckled beam, influences of an axial displacement on dynamic properties in chaos are clarified by numerical analysis. Especially, the chaotic vibrations bifurcated from 1/2 subharmonic resonance are focused on. The beam is constrained by an axial elastic support and both ends of the beam are clamped. Applying Galerkin method to the basic equation of the buckled beam in consideration with geometric non-linearity, nonlinear cubic simultaneous equations in multi-degrees of freedom are reduced. Further, the equations are transformed into nonlinear ordinary differential equations using normal coordinates corresponding to linear natural modes. By integrating the equations numerically, time histories and Poincare sections are calculated. Moreover, Lyapunov dimension can be obtained using the evolution equations. According to the calculated results, initial axial displacements increase the number of governing modes in the chaos including dynamic snap-through.

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The transverse vibrations of ropes of a high speed elevator are caused by a resonance with sway of building which is subjected to an earthquake or big wind, hence, an effective solution is demanded. In this research, it is performed to suppress the vibration of elevator rope by using a control device which is located near the upper boundary of rope. The control device has gaps between an actuator and the rope because of preventing abrasions of rope. Furthermore, the nonstationary sliding mode control is effective for the control of a time varying system such as elevator ropes and crane wires and robust for the nonlinearity of a control device. Therefore, this paper presents the vibration control for the elevator rope based on the nonstationary sliding mode control method by using control device with the gaps. The control effectiveness in the case of input saturation, stroke limitation or gap expansion and the robustness of the proposed method in the case of parameter variation and model errors are demonstrated by the numerical calculation. Consequently, the numerical results indicate that the performance of the proposed method is remarkable.

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This paper presents a new method for identifying the stiffness of mounts under the condition of being built in a structural system as in practical use. A conventionally standard method is to identify an individual mount using a dynamic stiffness measurement equipment. In the new method, the stiffness values of mounts built in a structural system are identified using the modal parameters of the system which are obtained by experimental modal analysis. Vibration testing of the structural system with a posture in an operational condition can make it possible to consider preload effect that is caused by the gravitational and thrust force applying to the structural system in practical conditions. Additionally, vibration testing using impact hammer is often made available so that the new method can make it much easier to identify the stiffness of mounts than the conventional measurement of dynamic stiffness. In this paper, the validity of the method is demonstrated using both a simulation study using a finite element model and an experimental identification of an actual outboard engine. The experimental result shows a dependence of the mount stiffness on the gravitational force and the thrust force at the propeller of the outboard engine.

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This paper describes the prediction on attenuation of a silencer equipment with many resonators by using FEM. The purpose of this study is to predict the attenuation of the silencer equipment in order to realize the reduction of infra-sound which generates in various plants. The attenuation is firstly predicted by a conventional method and secondary calculated by FEM. In modeling of FEM, An optimal mesh number is determined so that the variation of the natural acoustic frequency becomes within 10%, of the detail model by calculating of various mesh models. Because the fine mesh model consumes much time to calculate. Finally, the experiment is conducted and the calculated result is compared with the experimental one. As a result, it was clarified that the attenuation of the complex silencer with many resonators could be predicted by FEM with accuracy of ±3% and the conventional method could also be Predicted by taking into account of 70% the value of the calculated result. However it should be noticed that this fact is not universal.

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The purpose of this study is to realize the comfortable swinging fitted in the condition of each individual person. A simple active rocking chair is developed, which changes the swinging with the heartbeat fluctuation of the person. The active rocking chair is driven by a solenoid for the safety and the silence. The swinging is strengthened, when the period of the heartbeat is lengthened, and it is weakened in shortening case. The swinging is evaluated using the 16 scales questionnaire which was developed for an evaluation of a comfortable swinging on the basis of the SD method. As the result, it is confirmed that the comfortable swinging is realized by the developed active rocking chair. Then the acceleration near the ear of the rocked person is measured in order to examine features of the comfortable swinging with the feedback of the heartbeat fluctuation. And, it is clarified that the power spectrum of the envelope of the acceleration waveform shows “1/f fluctuation”.

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An approach is presented to the modeling of a two-dimensional permanent-magnetic passive damper proposed before. For the magnetomotive force caused by the displacement of a moving core, Maxwell's equations are solved with the Laplace transforms under some assumptions that simplify the equations to obtain an analysical solution. The distribution of the incremental magnetic intensity gives the incremental magnetic flux density around the moving core, and thus relates the displacement to the net force on the moving core. The tranfer function between the net force and the displacement defines the magnetic stiffness that is a complex number with positive real and negative imaginary parts when evaluated in frequencies. The magnetic stiffness is first derived with Bessel's functions of complex numbers, and then simplified with a hyperbolic function of complex numbers and a very simple form in higher frequencies. The numerical result is checked in good agreement with experimental results.

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Frequency characteristics of magnetic flux in magnetic actuators are analyzed through a one dimensional model. The subject is formulated as the flux penetration into the iron core from the pole face for a given magnetomotive force. First, the two-dimensional distribution of the magnetic intensity is obtained. The numerical results check the effect of the distribution near the pole faces and the magnetic-flux concentration near the surface of iron core. The results also show the effectiveness of a simple model without the pole-face effect, presented before, in higher frequencies and/or longer iron cores. Next, the simple model is used to examine the effect of magnetic saturation. The numerical result shows the degeneration of the magnetic flux higher than that in the case without saturation. This coincides with the difference between an experiment and a model, and suggests that the modeling should consider the effects of magnetic-flux saturation.

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This study aims at development of Intelligent McKibben actuator, in which micro displacement/pressure sensors and micro valves are integrated. In this first report, development of rubber displacement sensor and its application to servo system using McKibben actuator are reported. Recently McKibben actuator attracts engineers because of light weight, high output power and high compliance. But in case of servo control using it, the systems need encoders or potentiometers, so the systems tend to grow in size and to take away from compliance at present. To solve thus problems, soft rubber sensor was developed, which was made of rubber covered its surface with conductive resin thinly. Electrical resistance of rubber sensor changes in response to extending motion of the rubber. We built the rubber sensor into McKibben actuator and named it Intelligent McKibben actuator. Servo system using single Intelligent McKibben actuator was realized, and tested. Furthermore, we fabricated a robot arm system configured by two Intelligent McKibben actuators. Experimental results showed that the actuator has good potential for realizing polymer made intelligent actuator.

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We calculated the characteristics of contact force and adhesion force between a contact pad and a magnetic disk surface which has computer-generated asperities with Gaussian distribution. In calculation, we considered asperity contact, bulk deformation and meniscus force of the lubricant. First by comparing the results of our model with numerical GW model, we found that the bulk deformation becomes predominant when the asperity density is large and the rms value of asperity peak height is small as cases of current slider and disk surfaces. Next, we examined effects of asperity density, contact pad area, rms value of the peak height, asperity radius and lubricant thickness on the resultant contact force, adhesion force and the contact stiffness as a function of separation between contact pad and disk. It was found that the rough surface can be modeled by a simple bulk contact force and attractive force can be modeled as a constant adhesion force when the asperity density is large and the rms value of asperity peak height is small as the cases of current slider and disk conditions.

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In recent years, security problems have been concerned in the well-developed information society. Although authentication methods such as password-systems and key-systems are used widely, various problems are pointed out. Therefore, biometric authentication which uses the information of personal characteristics is highly paid attention to. In the present study, a new biometric authentication system using finger friction is proposed. This system utilizes tactile information of which recording and playing technologies have not been established, in contrast to visual and auditory information. Moreover, it is using both physical characteristics related to the 3-D shapes of fingerprints and behavioral characteristics related to the way of rubbing. In the present system, PZT sensors generate frictional signals when a subject rubs them with its finger. As the result of verification, it is found that some statistics and dynamic programming enable to identify the subject with the frictional signals.

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In a ship steering system, the velocity of rudder angle often saturates. It is caused by oil pressure servo mechanism. It is important to steer the ship avoiding saturation for the purpose of precise course control. The limiter of rudder angle and control command is also used for safety and it is the custom for helmsman to reduce over shoot of heading. These control rules become constraints of state in the ship steering system. In this paper, a finite settling time control is proposed considering some saturation and constraints of ship steering system. And robustness for disturbance is also satisfied by this control. The effectiveness of this control is verified by numerical simulation using a ship model.

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This paper deals with a method of optimal acceleration vibration contol using receding horizon control. In order to compare this method to LQ control, the simulation using a quarter-car model was carried out with random road surface excitation. As a result, it is clarified that the effects of this method are superior to LQ control the criteria of which was described with acceleration. The ride comfort of vehicles is related to the vibration revel of acceleration, so this method possesses high potential to reduce vehicle vibration and to improve ride comfort.

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For reducing traffic accidents by aged drivers, researches on active and passive safety technologies and driver characteristics have been carried out. however, several research achievements are not so effective for aged drivers since the characteristics of aged drivers are distinguished from normal drivers and difficult to analyze. In order to clarify the distinguished factor of aged drivers, this report is based on the assumption that aged drivers' driving characteristics are strongly related to both their lifestyle and physical characteristics. The driving characteristics, the lifestyle, the physical characteristics are investigated from several questionnaire surveys followed by experiments, by using reaction test and actual driving test. The evaluation method of aged drivers' driving performance is proposed based on lifestyle and physical characteristics, and this method provides useful suggestions for understanding the aged drivers' driving characteristics.

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This paper presents a novel liquid cooling concept for heat rejection of high power electronic chips existing in notebook computers etc. In order to realize a liquid cooling system for the electronic chips, such as advanced notebook CPUs, a simple thin-planar pump using electro-conjugate fluid (ECF) is proposed, fabricated, and experimentally investigated. The ECF is a kind of dielectric and functional fluids, which generates jet flows (ECF-jets) by applying static electric field through a pair of rod-like electrodes. The ECF-jet directly acts on the working fluid, so the proposed planar ECF pump needs no moving part, produces no vibration and noise. The experiments of the fabricated thin-planar ECF pump with A 4 size were performed with four different flow channel heights and seven different electrode patterns. The no-load flow rate of 5.5 cm³/s, maximum output pressure of 7.1 kPa, and maximum output power of 11.6 mW are obtained at an applied voltage of 2.0 kV. Through the experimental results, the fesibility of the thin-planar ECF pump is confirmed as a power source of the liquid cooling system on advanced notebook computers.

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There exist two, four or six solutions of the output angle of the Stephenson six-link mechanism of type III, which is composed of the constituent four-link mechanism and the driving two-link chain, for any value of the input angle. These solutions correspond to link-chain configurations in different domains of motion of the driving link. Domains of motion are corresponded to either parts of the coupler curve of the constituent four-link mechanism which are separated by two limit points or connections of two parts separated by limit and turning points, or the coupler curve or its parts separated by two turning points. So, domains of motion are mapped on four number-lines of the input angle which are discriminated by the sign of the determinant of the equations of the velocity analysis and the sign of the sine of the relative angle of the driving two-link chain. Consequently, all relationships between input and output angles are calculated as a continuous function. In this paper, the identification method of the domains of motion is expanded the grashof's condition, that is, the algorithm for judging whether the driving link can make a continuous rotation in one direction or not.

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The present paper deals with a method to estimate thermal deformation of spindle of a machining center based on the temperature changes measured at the spindle head. It is confirmed by experiments that the nominal time constant of the thermal deformation due to the heat input caused by the spindle rotation is much influenced by the rotational speed of the spindle as a consequece of changes in the heat transfer coefficient between the spindle and the ambient. The relation between the time constant of thermal deformation and the rotational speed of the spindle is obtained experimentally for various rotational speeds. The results are summarized as the transfer function coefficients. A method is proposed to estimate the equivalent heat input based on the temperature change at the spindle heat by utilizing the measured transfer function, and then estimate the thermal deformation of the spindle based on the equivalent heat. The validity of the proposed method is proved by experiments applied to two kinds of machining centers.

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Due to the advancement of micro-machining technology, development of measuring method for both profile and dimension of micro-components has been strongly demanded. One of the methods available for this is a small three-dimensional profile measuring apparatus with micro-probes. For this purpose, we have investigated fabrication technologies for micro-probes that are used for a small three-dimensional coordinate measuring machine. However, machining of rather complicated probes such as slanting probes as described in the ensuing section, is very difficult due to unstable machining conditions. Thus, long time is required for probe fabrication, and it is sometimes impossible to continue the normal machining due to improper flow out of the cutting chip powder. From this reason, we have tried implementation of the fundamental experiments on vibration-assisted micro-EDM, which considered to be effective to increase machining stability. The results clearly indicate that the vibration of tool electrodes has a major influence on the machining speed. In this report, at first micro-probe fabrication methods using micro-EDM were described, then the results of fundamental experiments on the effect of vibration frequency, amplitude and direction of vibration will be described.

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The contact stiffness between grinding wheels and workpices has been numerically analyzed by applying the theory of Hertzian contact, in which a wheel is considered to be uniform continuous body. It is well known, however, that the grinding wheels are not actually uniform continuous bodies. Consequently, when analyzing the elastic deformations of grinding wheels, the theory of Hertzian contact should not be applied as it is. In this study, in order to clarify the mechanical phenomena of grinding wheels in the contact area with workpieces, a mathematical model of grinding wheels consisting of rigid bodies and spring elements was proposed. By utilizing this model, elastic deformations of the grinding wheels in the contact area with workpieces are considered. And analyzed results are confirmed experimentally. From these results, it is clarified that the elastic deformations of grinding wheels in the contact area with workpieces can be analyzed quantitatively by means of the proposed model.

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This paper shows a new safety system to know the human existence in the machine moving area of large scale product lines. It is very difficult to create such a system because the operator can enter into the machine moving area without pulling out of the interlocking key, and there were not only nominated operators but also non-nominated operators. New concept of the risk management division (I : safe condition, II : uncertain condition, III : hazardous condition) was proposed to evaluate the risk reduction of such system. The risk reduction to the division I can be achieved by direct monitoring devices such as the laser scanning sensor. It can be achieved also by indirect monitoring devices such as the mechanical counter gate. On the other hand, the risk reduction to the division I cannot be achieved only by the plug, key-switch or movable guard.

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