In this research, we propose a vibration energy harvesting (VEH) system contributing to structural health monitoring in many spacecraft. Among four types of VEH – electromagnetic, electrostatic, piezoelectric, and magnetostrictive - we exploit the magnetostrictive vibration energy harvester in this research because of its strength and workability. The magnetostrictive type is composed of a magnetostrictive material. This material is one of the metal materialsthat showsthe Virari effect. The magnetization of the material varies when external force is given to the material. Following Faraday’s law of induction, a solenoid coil picks up electrical energy when the magnetization varies magnetization. This is the principle of magnetostrictive VEH system. We focus on the control method and the construction of the electric circuit connected with the magnetostrictive element. Although, in the past many researchers used the passive circuit, also called standard circuit, the author thinks the nonlinear switching circuit has more potential because of flexible control and vast scope of application. Indeed nonlinear method suggeststhat magnetostrictive VEH system could drive many kinds of electric devices especially when they have high load impedance. This notion is based on semi-active damping method. The nonlinear method uses switching circuit and passive elements and makes the electric current increase with the switch process. As a mechanical vibration isinduced by an oscillator, part ofthe mechanical energy is transformed into electrical energy and the mechanical energy decreases. This paper presents nonlinear control circuit with a switch and control logic, and an analysis of mechanical and electrical dynamics. As a result of the analysis in the case of a vibration with 1 degree of freedom when a force oscillation is applied, we conclude that both the electrical power supply from the mechanical system and the harvesting energy in load resistance increases.

In this paper, theoretical modeling and analysis of a diamagnetic levitation-based vibration energy harvester having low resonance frequency (< 2 Hz) is presented. The system fundamentally consists of four objects, i.e., a floating magnet, lifting magnet and two diamagnetic plates. We adopt the magnetic dipole model for modeling the attractive force between the floating and lifting magnets, and the thin coil model and the discrete volume method for modeling the diamagnetic repulsive forces come from two diamagnetic plates. In addition, an equilibrium position of the floating magnet on horizontal and vertical directions are discussed. In the presented model, the influence of the tilting motion of the floating magnet and the electromagnetic effect of the induction coil are neglected. Finally, a time history response analysis of the floating magnet is performed by solving the equations of motion. The results show that the presented harvester has the resonance frequency of approximately 2 Hz.

This paper proposes an easy-to-use optimization method of actuator location on smart structure evaluating controllability and modal strain energy. Generally, the location of the actuator greatly affects the control performance. In this paper, the controllability Gramian is used as a objective function for PZT actuator location, and it's obtained from a state space equation derived from FE model. Additionally, the modal strain energy obtained from FE model is evaluated as an indicator of optimal actuator location. Particle swarm optimization is used as the algorithm of the optimization. In this paper, an active vibration control system using H-infinity control theory is used to suppress the vibration, and vibration control experiments using the optimized actuator locations are carried out, and the results are argued. As the result, the control system using the optimized actuator location shows high control performance for easy method. From these results, the proposed optimization method is easily and effectively used for suppressing the vibration of the structure.

Electromagnetic transducers have the characteristics of actuators, sensors, or both. By using these characteristics, there is the vibration control technique that called electromagnetic shunt damping. This technique is passive damping, and therefore, modeling accuracy of electromagnetic transducer is very important, in especially high frequency. However, we observed that conventional model of electromagnetic transducer does not match the experimental results of frequency responses in high frequency. This paper proposes a novel model which has higher accuracy compared with conventional model in high frequency. To improve the modeling accuracy in high frequency, this paper derives the novel model of electromagnetic transducer considering eddy current generated in electromagnetic transducer. The derived model is represented as an irrational transfer function. The validity of the proposed model is demonstrated by performing experiments. The experimental result shows that the accuracy of the proposed model is higher than that of the conventional model.

The magnetorheological elastomer (MRE) is known to belong to a class of smart materials whose elastic properties can be varied by an externally applied magnetic field. In addition to the property of the field-dependent stiffness change of the MRE, the electrical resistance of the composite is also changed by the induced strain, thereby providing a new self-sensing feature. In the present study, the MRE is focused on dispersed particles having conductivity and applied to a sensing property, and the electrical resistance of MREs is evaluated. The electrical characteristics test using MREs that are created in a variety of conditions shows that the electrical characteristically resistance changes with the increasing or decreasing load of the compression direction.

Bolted joints are widely used in mechanical and architectural structures. However, many serious accidents occur because of loosening in bolted joints. The diagnosis of the bolt loosening is able to achieve by evaluating the variation of tightening axial tension. Conventionally, the inspection method of the loosening bolted joint is generally the measurement of the axial tension of a bolted joint by using ultrasonic waves. These methods require the use of special measurement equipment and the human operation. In this study, a smart washer was proposed to detect the loosening without human involvement. The basic principle of how to detect the bolt loosening is based on the smart washer dynamics perturbation depending on the tightening axial tension for bolted joint. The smart washer used in this study is in cantilever type with piezoelectric material, which adds the washer of the self-sensing and actuating function. Previous research had indicated that a correlation was confirmed between the natural frequency of the smart washer and the tightening axial tension with the theoretical and experimental results. The subject of this method is to identify the natural frequency of the smart washer by changing the bolt tightening axial tension, which is using the self-sensing and actuating by applying the piezoelectric material. In this paper describes the natural frequency identification method for smart washer with the adaptive observer by variable adaptive law. While the tightening axial tension changes, the initial parameter vector is updated every investigation period. It is appropriate that the identified value just before the investigation period is adopted as the initial parameter vector for new period. The influence of initial parameter vector will be considered with simulations when applying the adaptive observer.

Active damping technology is one of the effective ways to reduce vibrations. But, the active damping technology is usually applied only for large-size objects such as buildings or trains with the custom-made design because it requires technical knowledge, much man-hour and cost to design. There are few solutions to reduce vibrations after the vibration problems are happened once in product developments. In this study, an all-round active damping system which can be applied for various relatively small-size equipments with add-on style after vibration problems come about was proposed and the features of the system were described. Subsequently, a controller developed for the proposed all-round active damping system was described. This is a distributed controller using real-time network technology and enables following features; high-speed, compact, lightweight, and scalability of I/O number. Finally, as a basic verification, an active damping system with the developed controller was constructed for a metal case as a sample. The gains of resonant peaks from 100 to 300 Hz were damped more than 9.5 dB and it was indicated that the developed controller could be used for the active damping system.

Static and dynamic characteristics of journal bearings with uniform square dimples on the whole bearing inner surface were experimentally investigated. A test rig was developed to measure the static and dynamic characteristics of journal bearings. Three kinds of journal bearings were used for the test bearings which include two journal bearings textured with square dimples by the electrical discharge machining and a plain journal bearing without dimples. The eccentricity ratio, attitude angle and the stiffness and damping coefficients were measured for a wide range of Sommerfeld numbers and were compared with the corresponding results of a plain bearing. The experimental results showed that the textured journal bearings have larger eccentricity ratio and smaller attitude angle than a plain bearing and reduce the magnitude of the cross-coupled stiffness coefficients. The quantitative effects of texturing on the eccentricity ratio, attitude angle and cross-coupled stiffness coefficients become more marked for higher Reynolds number and larger number of dimples under the constant dimple area. This is attributable to the fact that the energy loss at the edge of dimples increases with Reynolds number and total edge length.

In the present study, the static characteristics (leakage flow rate) and dynamic characteristics (dynamic fluid film forces, dynamic coefficients, and whirl frequency ratio) of the helically grooved seals are experimentally investigated for various rotor spinning velocity, pressure difference, and groove dimensions. The results show that the leakage flow rate Q for the helically grooved seals decreases with helix angle γ and groove width g_w, and it becomes lower for small γ and g_w than that for the smooth seal. The cross-coupled stiffness coefficient K_c and whirl frequency ratio WFR of the helically grooved seals are smaller than those of the smooth seals and their values are always negative for any γ and g_w tested. The results obtained suggest that the helically grooved seals with small γ and g_w yield better performance characteristics from the viewpoint of reduction of leakage flow rate and suppressing the forward whirl motion of the rotor.

For the sealing device for rotary bodies such as turbo compressors, labyrinth seals are using because of a non-contact seal. In recent years, labyrinth seals have been required that improvement of sealing performance along with increasing pressure of turbo machineries. In this paper, it is suggested that new step seals (Groove-step seal) have high sealing performance only wearing grooves in the axial of fundamental step seals. This study was carried out by CFD analysis. First, optimal groove structure was shown by study of changing the width and depth of the groove in the rotor of step seals. And then, it became clear that Groove step seals have effect of reducing leakage up to 22 % compared to general step seals. Further, it was shown the sealing effect range of axial gap between the rotor and stator by verification of the CFD. And it was confirmed that Groove step seals have the effect of reducing leakage, if the pressure condition has changed.

Gas foil bearings (GFBs) are expected to be used in a variety of turbomachinery such as turbocharger, compressor, air cycle machine. One of the main issues for implementing the GFB to the turbomachinery is wear due to rubbing between shaft and bearing. In order to reduce wear, it is important to precisely predict and lower the speed of lift-off. This paper presents measurement by the test rig for the evaluation of the lift-off speed. During the lift-off test, the drag torque of the GFB was measured and the lift-off was detected by its value. The static load applied to the GFB was varied from 2 N to 5.2 N and the influence of the load on the lift-off speed was estimated. The predicted lift-off speed corresponded with the measured value. It was found that pre-load of GFB is the main factor to determine the lift-off speed in the low static load condition, and contrary to the expectations, static load has little influence one the test results. Finally, this paper proposes the way to lower the lift-off speed.

Hydrostatic gas journal bearings can contactlessly support rotors by gas pressure. They provide advantages such as high precision rotation, high speed rotation and low friction loss. However, the load capacity of gas bearings is very small in comparison with rolling contact bearings, so they have been mainly applied to small size rotating machinery. In order to support heavier rotors and unbalanced rotors, we have developed an asymmetric gas supply system for the bearing. The system is supplied different gas pressure to the bearing from multiple supply holes in accordance with rotational state of the rotor. A test rig was fabricated by authors and a rotating test was carried out to verify the advantageous. The test bearing has diameter of 60 mm and the length of 120 mm. The results of the numerical simulation using non-linear orbit method was compared with the test results. Each approaches showed that the asymmetric gas supply system can be reduced the rotor vibration compared with the conventional symmetric gas supply system.

Axial thrust forces acting on an impeller of a diffuser type mixed flow pump have been studied. The behavior of the axial thrust generated by the vortex occurrence in a pump intake sump was investigated. The thrust of distinct discontinuities such as hysteresis phenomenon from a pump hydraulic performance was measured. In pump partial load operation the axial thrust increases discontinuously because of the reverse flow at impeller inlet. Synchronous and non-synchronous components of axial thrust increase during the onset of reverse flow zones. A prediction method for static axial thrust was derived based on Oshima's theory accounting for the pump suction bell-mouth pressure reduction due to vortex. Qualitative comparison with the measured experimental results for static axial thrust showed reasonable agreement around pump best efficiency flow rate. The pump intake sump test apparatus，in which both an air-entrained surface vortex and a submerged vortex will occur，was employed and the axial thrust was measured. The level of axial thrust is dependent on the pump intake sump water level. The dynamic axial thrust begins to increase due to the occurrence of a full air core vortex to intake. When submerged as well as full air core continuous vortices occur，the axial thrust and the fluctuation of total pump head become abruptly large. The fluctuation of axial thrust becomes the highest when the impeller sucks the air-drawing large vortex imposing a pressure fluctuation which generates not only a rotational speed but also nZ vane passing and low frequency components.

In this paper, vibration characteristics of a vertical rotor system were investigated. Both the additional degree of freedom of the journal bearing support portion and rotor dynamic(RD) nonlinear fluid force by the journal bearing were considered, and their effects on the vibration characteristics were investigated, numerically. As a result, it was observed that an existence region of self-excited vibration was reduced by supporting the journal bearing flexibly. Moreover, influence of parameters; stiffness for the support part, a damping for the support part, and radial clearance, on the vibration phenomenon was clarified.

High pressure multi-stage pump is one of the most important machinery in various plants. Due to the high rotational speed, there are cases where excessive vibration problems occur. Especially, the self-excited vibration arises from the fluid force, which exists within the clearance of the oil film bearings and balancing drum (annular seal). Therefore, it is important to evaluate the stability limit（onset of self-excited vibration）at the design stage. However, the accuracy of the calculation tool is not sufficient at present. Thus, a special measurement tool is needed to analyze the phenomenon of actual equipments. For this reason, we aim at developing an excitation system to evaluate the stability limit by utilizing an active magnetic bearing as an exciter. First, we devised an excitation theory based on Bently-Muszynska model. According to the theory, the stability limit can be evaluated by rotor natural frequencies, and fluid average velocity within the clearance of bearings and balancing drum. In order to measure these parameters, we applied the system to excitation tests, which included the rotating test in air, and in water, respectively. The difference between the tests is whether the fluid force in the balancing drum exists or not. Through the test results, the balancing drum had a significant effect on the rotor stability, and the self-excited vibration occured at the intersection of the natural frequency and fluid average velocity in the balancing drum. Moreover, the resulting frequency（0.72×rotational speed）matched the fluid average velocity (0.73×rotational speed) in the balancing drum.

Torsional vibration of engine occurs because the driving torque of engine changes periodically. Recently, noise caused from this torsional vibration is getting serious problem. A centrifugal pendulum vibration absorber (CPVA) is one of the vibration suppression devices for this kind of torsional vibration of engines. In this study, vibration suppression mechanism of CPVA was investigated for 1DOF rotor system. First, a numerical simulation for the nonlinear model of CPVA was demonstrated, and its vibration suppression effect was confirmed, numerically. Then, the natural frequency analysis was demonstrated and the vibration suppression mechanism of CPVA was explained by it. Furthermore, super-harmonic resonances caused by the influence of CPVA’s nonlinearity were also explained.

A vane used in a low pressure end of steam turbine is usually fixed to an inner shroud and an outer ring by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In addition, steam turbine vanes are sometimes manufactured in a half-ring structure, where all vanes in a upper half and a lower half are connected by the shroud. In such a half-ring structure, the vane exhibits closely spaced natural frequencies of Toop (Tangential out-of-phase) modes, in which each vane in a half-ring vibrates like a fixed-fixed beam in a different phase. In such a steam turbine vane, the forced vibration and the self-excited vibration of Toop modes may become a serious issue. Therefore, in the design of the steam turbine vane, it becomes indispensable to evaluate the resonant response and the stability of Toop modes under the high loading condition. In this study, first, the vibration characteristics of steam turbine vane with a half-ring structure are studied by use of the results of FE analysis. Second, the reduced order model (the equivalent spring-mass model) of a half-ring structure is assembled, based on the results of FE analysis. Finally, the forced response analysis of the mistuned system of a half-ring structure is carried out, using the reduced order model and the Monte Carlo simulation. From these results, the vibration response characteristics of steam turbine vane with a half-ring structure are clarified.

When calculating the resonant response of bladed turbine disks, it has been convenient to assume that all blades on a given disk are identical. This leads to the prediction that all blades experience the same amplitude of displacement and stress when excited by forces harmonically related to the rotor speed. However, it has been shown experimentally that significant variations in these amplitudes occur for different blades on the same disk. These variations arise due to the effects of mistuning, which refers to small differences in characteristics between blades. In this paper, a reduced-order model is created with modal data from eigenvalue analysis in Nastran (RESVEC method). After creating a whole-blade model by component mode synthesis, eigenvalue analysis is carried out again and the modal data is sorted to pick out modal family data. This frequency analysis is faster than FEM because the final degree of freedom is equal to the number of blades. This method is verified for the 1st and 2nd mode family of a simple bladed disk with flat plate blades, and a Monte Carlo simulation is carried out. Finally, this method is applied to an actual bladed disk used in steam turbine.

Recently, the blade with friction damper has been used in the steam turbine and gas turbine to improve the blade reliability. Especially, for the long steam turbine blade of the low pressure end, the shrouded blade has been widely used, where the shroud of the blade on a disk gets contact with each other due to untwist deformation of the blade in rotation. The shrouded blade is designed so that the shroud surface gets contact with the adjacent shroud surface uniformly. The contact condition of the shroud (in other words, the equivalent stiffness and the damping caused by the shroud), however, may change remarkably blade by blade, because of the manufacturing tolerance, the blade deformation in operation, the wear of the shroud, and so on. Therefore, it is indispensable to consider the mistuning effect caused by the variation of the contact condition of the shroud, in evaluating the resonant response of the bladed disk with the shrouded blade. In this study, first, the nonlinear frequency response of the shrouded bladed is carried out, and the linear equivalent spring-mass model is assembled based on the results of the nonlinear analysis. Second, the response analysis of the mistuned bladed disk is carried out by use of the equivalent spring-mass model. From these results, the effect of the variation of the contact condition of the shroud on the response is clarified.

Karman vortex shedding occurs when the gas passes through the duct with tube bank of the heat exchangers, such as gas heaters and boilers. Very high level sound in called “self-sustained tones” occurs due to the interference of the vortex and the sound field in the duct. In general, baffle plates are used to suppress the self-sustained tone. However, it is difficult to use them effectively, because insertion conditions have not been established. Then, perforated plates are installed in both sides of the duct to suppress the self-sustained tones. As a result, it was clarified that the perforated plate could suppress the self-sustained tone as expected. However this experiment was conducted using perforated plates with aperture ratio over 1% and the suppression effect appears in all of these aperture ratios. Wherefore the critical aperture ratio at which the suppression effect begin to appear could not be grasped in that experiment. This paper aims to clarify the critical aperture ratio and the effect of a cavity volume which is used with perforated plate on the SPL. Experiments were carried out to clarify these items. As a result, it could be obtained that the critical aperture ratio is about 0.25% and the influence of the cavity volume on SPL is a little. The optimum aperture ratio is concluded to be 4%.

This research is refer to reduce aerodynamic noises at the exhaust systems of the truck equipped with a diesel engine. This paper, focuses on a butterfly valve in the exhaust systems. This research clarifies the property of aerodynamic noise generated by the butterfly valve during an opening operation. The noise was measured by changing the opening time. The experimental results show frequency characteristics of the noise is strongly related to the angle of the butterfly valve. Also, to slow down the opening operation of the butterfly valve, effect on the suppression of aerodynamic noise.

Aerodynamic noise is a problem in an exhaust system of large size diesel engine in factories. Because of high-speed exhaust gas, the low frequency aerodynamic noise generates in the silencer. Precisely, aerodynamic noise is related to the formation of vortex. Therefore, we focus on perforated metal which is effective to reduce the scale of vortex. Perforated metal is produced by punching the sheet metal using a press die. It has two kind of direction by its cross-sectional shape. One is “Expansion” the other is “Shrinkage”. In this paper, we measure the aerodynamic noise generated by the airflow through punched small holes. Experimental condition change number of holes, direction of the plate and thickness of it. As a result cross-sectional shape has effect on vortex formation and interference of vortex. When the thickness is increase, it is the effective cross-sectional shape for aerodynamic noise.

In the present paper the attention is focused on vortex shedding synchronization in in-line tube banks on acoustic resonance which occurred in the two-dimensional model of boiler. We measured the characteristics of acoustic resonance, the pressure fluctuation on the surface of tubes at the nodes of acoustic pressure and the acoustic pressure fluctuation on the side wall. If the acoustic resonance occurred, the peak level of spectrum of surface pressure difference and the coherence between vortex shedding and wall acoustic pressure in the tube banks also increased. The vortex shedding from the tubes have synchronized with particle velocity fluctuation due to acoustic resonance. We discussed the phase relation between the wall acoustic pressure and measured surface pressures which are related to the lift force on a tube and acoustic particle velocity near the tube.

It is considered that RR interval (heart beat interval) and blood pressure fluctuate under the influence of circulation control by autonomic nerves and pulse wave propagation. Based on the above, we combined the model of a circulation control and the simulation of pulse wave propagation taking FSI effect into consideration, and constructed a coupling model capable of calculating RR interval and blood pressure value according to the state of autonomic nerves. After that, we confirmed whether the coupling model can reproduce the relation between RR interval and sleepiness observed experimentally. In the beginning, we investigated a factor which has an influence on the formation of pulse waveforms. As a result, the flow velocity distribution which determines viscous term in the Navier-Stokes equation has a great effect on formation of pulse waveforms. On the other hand, viscoelasticity of blood vessel walls has few effects. Next, considering the interaction between circulation control and pulse wave propagation, we constructed the coupling model. In this coupling model, we reflected the change in the stiffness of blood vessels. This is because blood vessels become narrower and the stiffness increases, if sympathetic nerves become predominant. Comparing the results of calculation by the coupling model and only the model of a circulation control, it was found that in the coupling model we successfully reflected the action of resistance in a blood vessel.

In this study, we target at Pulmonary Hypertension. The good treatment of the timing is essential to the disease that is an intractable disease. Now, the diagnosis method of the Pulmonary Hypertension called the Pulmonary Vascular Resistance (PVR) is used in medical care. However, this diagnosis method is vague. This is caused by the conditions except the blood vessel. The main purpose of this study reported here is to consider pulmonary artery as an elastic duct line and analyze an internal wave motion phenomenon and to propose the new diagnosis method of the Pulmonary Hypertension．

Flow-induced acoustic resonances in piping with closed side branches or T-junctions are one of the phenomena causing severe structural vibration and fatigue damage of piping and components in many engineering applications such as power plants. In the United States, the steam dryer of the boiling water reactor was damaged by high-cycle fatigue due to acoustic-induced vibration under a power uprating condition. Practical piping systems of power plants often have a steam flow, and moreover, the steam state can be not only dry steam but also wet steam, including nearly saturated conditions. Although many researchers have investigated acoustic resonances at side branches and T-junctions, it is considered that acoustic resonances under a wet steam flow have not yet been clarified since previous studies were mainly conducted under an air flow, and there have been few previous experiments performed under a steam flow, particularly a wet steam flow. The objective in this study is to investigate acoustic resonances in closed side branches with tandem- and coaxial-type arrangements under a wet steam flow. Experiments under a low-pressure condition for dry and wet steam flows were conducted and the results were compared. As a result, it is clarified that the effect of branch arrangements (single, tandem, coaxial) on the resonance amplitude under steam flow. In addition, differences in the amplitude response between dry and wet steam were evaluated.

When evaluating riding comfort of vehicles, sometimes human dummy developed by spring-mass-damper system is used to avoid individual variation. However, because the human body is continuum, such kind of dummies cannot completely represent the vibration characteristic of the human body. Therefore, to represent vibration characteristic of human body as continuum, new types of dummy developed by soft structure filled with fluid, which were defined as aqua dummy, were contrived and as the first step, vibration characteristic, especially apparent mass, of the dummy was examined by simulation and experiment. However, because the simulation of dummy's vibration characteristic was calculated by two dimensional model, although aqua dummy was practically a three dimensional structure, the result of the simulation was different from the experiment's result regarding apparent mass. Therefore, in this paper, the new simulation model in the three dimensional calculation is constructed to represent the vibration characteristic of aqua dummy exactly, and reveals that the parameters of the structure have a big influence on dummy's vibration characteristic. Moreover, the result of calculation by the new model applied to two vibration experiments is found to approximately accord with the result of experiments regarding not only apparent mass and the primary natural frequency but the deformation of dummy. In conclusion, the three-dimensional model is beneficial to produce human dummy of aqua dummy.

Apurpose of this research is to develop a simplified dynamic model for a free standing spent fuel rack (FS rack) and to propose design guidelines of the FS rack. The FS rack is designed to suppress a movement caused by seismic excitation due to fluidstructure interaction effect of clearance flow between a neighboring rack and wall of a storage pool as well as due to friction between rack pedestals and bottom surface of the pool. Therefore, the FS rack under earthquake excitations probably shows various motions such as translation sliding, rotation sliding, and rocking. In this research, we developed a quasi-3-dimensional dynamic model for a single FS rack by combining two 2-dimensional numerical models, the translational-and-rotational model, and the rocking model. To validate the proposed model, an experiment with a 1/16 scale reduced model of the FS rack was performed and the results were compared with the calculated results. Then, the full-scale FS rack under the actual acceleration of the earthquake wassimulated by using our proposed model. As a result, it is found that coefficient of friction has an important role in the behavior of the FS rack and kinetic coefficient of friction might be changed by the effect of rocking vibration.

Sloshing phenomena in containers under earthquakes often cause serious accidents. In case of an oil tank with floating roof, the sloshing phenomenon and the structural vibration should be treated as the coupled problem. Lagrangian fluid finite element model has been used for the analysis of the coupled problem because the compatibility and the equilibrium condition are automatically satisfied at the boundary between the fluid and the structure. However, the degree of freedom of the Lagrangian model becomes large because the fluid particles in the Lagrangian model move vertically and horizontally. In addition, the Lagrangian model has physically-meaningless spurious modes caused by the redundancy of the degree of freedom. In this paper, to establish the efficient and accurate analytical model for the coupled problem, liquid in a rectangular container is modeled as the nonlinear concentrated mass model. The model consists of masses, non-linear connecting springs and connecting dumpers. Some masses move horizontally, the others move vertically. The horizontally movable masses are governed by the equations of motion. The vertical displacements of masses are determined from the displacements of the horizontally movable masses based on the incompressibility of the liquid. The characteristics of the connecting springs are derived from the static and dynamic pressures of the liquid. The degree of freedom of the proposed model is smaller than that of Lagrangian model and the spurious modes does not occur in the proposed model. To confirm the validity of the proposed model, the time history response of the model is compared with experimental result.

The nonlinear liquid motion in a partially filled rectangular tank with a core barrel is investigated. Basic equations are derived by employing the variational principle. Equations of motion governing nonlinear surface oscillations are derived by applying the Galerkin’s method to basic equations. Admissible functions are assumed to be represented by combining the modes of vibration. Because of complicated shape tank like a rectangular tank with a core barrel, the modes of vibration and the natural frequencies are not obtained by analytical method. Therefore, they are calculated by using the finite elements method. Occurrence condition of internal resonance were considered. In the case of a complicated shape tank, since the nonlinear coupling between the modes become vague, it is difficult to predict the internal resonant modes. By considering the coefficients in the derived nonlinear equations of motion of nonlinear coupling modes, an index to predict the mode of which amplitude may become large by internal resonance is proposed. Experiments were carried out at the condition when the nonlinear liquid sloshing occurs. The occurrence of the internal resonance was confirmed by the experimental results. It is shown that the amplitude of the predicted internal resonant mode become large in both analytical and experimental results. Effectiveness of the analysis and validity of the proposed index are verified.

This study addresses the coupled behavior between sloshing in a tank and a structure. It is motivated by design of liquid storage tanks, liquid cargo transportations, tuned liquid dampers, and so on. In particular, this paper focuses on development of coupling strategy based on the Hamiltonian mechanics for the constraint system with the Lagrange's method of undetermined multipliers. As a result of this formulation, it can be found that equations of motion of this system is given by the differential algebraic equations (DAEs) consisting of differential equations for the sloshing and the structure and an algebraic equation (constraint) for the momentum of structure motion and the liquid surface displacement. In order to calculate the DAEs formulated by the present method, this study employed a numerical integration technique based on the energy–momentum method. The proposed approach is validated by comparisons with an existing model and an experiment in the time domain analysis.

Dynamic stability of rectangular flexible plate often becomes problem. As the flexible plate, the papers in a high speed printing machine, the thin plastic and metal films, the fluttering flag and the oscillating doom roof are enumerated. By 2 dimensional analysis, there is a limit in application range of the aspect ratio. In this paper, dynamic stability of rectangular flexible plate is estimated in 3 dimensional model. The fluid is assumed to be treated as an ideal fluid in a subsonic domain, and the fluid pressure is calculated using the velocity potential theory. The coupled equation of motion of a flexible cantilevered plate is derived into consideration with the added mass, added damping and added stiffness respectively. Galerkin method and the complex eigenvalue analysis is performed for the stability analysis. In order to consider effect of 3 dimensional analysis on dynamic stability, results by 3 dimensional analysis was compared with them by 2 dimensional analysis. When the mass ratio of a fluid system for a structure system is small, the critical velocity calculated by 3 dimensional analysis is higher than that calculated by 2 dimensional analysis. And, when mass ratio is large, the critical velocity calculated by 3 dimensional analysis is lower than that calculated by 2 dimensional analysis. Moreover, in order to consider the effect of gap width of channel flow, the critical velocity is calculated in different gap width.

In this paper, Dynamics stability analysis methods of a beam subjected to a confined annular axial flow is dealt with. Such structures are submarine resources production pipeline, reactor core structures of nuclear power plants, high-speed trains passing thorough a tunnel, a piping system in the field of ocean mining, and so on. The relation between the annular axial flow velocity and the unstable dynamics of structures are clarified. We have compared two analysis methods which can evaluate the dynamic instability of such structures. In first analysis method, the fluid is treated as viscous fluid, and is governed by the Navier-Stokes equation, and the beam structure is treated as the Euler-bernoulli beam. This is called as the viscous fluid solution hereafter. In second analysis method, the fluid is treated as ideal fluid. Viscosity effect are added to the equation of motion. This is called as the ideal fluid solution hereafter. The complex eigenvalue analysis of the fluid structure coupled equation of motion is performed in order to clear up the dynamic instability. Performing the parametric studies, the comparison between both solutions is investigated. When the fluid viscosity becomes large, the difference in the critical velocity between the viscous fluid solution and the ideal fluid solution is found to be generated. The destabilization effect is recognized due to the fluid viscosity force terms of the added stiffness of the fluid-structure coupled equation in the viscous fluid solution.

This paper deals with the flutter analysis and experiments of a flat plate suspended by wires. In the flutter analysis, Doublet-point method based on unsteady lifting surface theory is used to calculate the unsteady fluid force acting on the plate surface. The theoretical model of the plate suspended by wires is derived by using the Lagrange equation of motion. Moreover, flutter velocity and frequency are examined through the root locus of the flutter determinant of the system with changing flow velocity. The influence of the suspending angle on the flutter velocity, frequency, and mode are clarified.

The method to design the optimal control to suppress the sheet flutter is proposed. This control method is based on the idea of LQ control. We derive the Riccati partial differential equation (Riccati PDE) using variational method. The functional feedback gains are obtained from this Riccati PDE using finite difference method. Finally, the effectiveness of this feedback law and optimality are evaluated. It was found that the control method by this designed optimal control law could suppress sheet flutter in numerical simulation.

This paper presents experiments and an analysis on the self-excited vibration of a plate on air flow and a support structure. The instability conditions and the vibration characteristics are examined using a theoretical analysis considering the effect air compressibility in a chamber. The system's characteristic equation is derived from the plate motion and the support structure motion coupled with equations of the gap flow between the plate and the support structure. The stability of the system is clarified by using the root locus. Moreover, the local work by the fluid force on the plate surface and the support structure surface is clarified by the energy analysis. Lastly, the unstable mechanism of self-excited vibration is discussed.

In-flow fluidelastic instability of tube arrays subjected to crossing flow is recently highlighted due to a practical problem occurred in 2012. Some features of this phenomenon have been revealed by some published papers. Parallel triangular arrays are found easy to occur this instability, but it can be hardly observed for square arrays. Then, next question is how about for normal triangular arrays. This study focuses on the phenomena in normal triangular arrays, which is usually observed in many heat exchangers. The pitch to the diameter ratio, P/D, are changed in three patterns, P/D=1.2, 1.33, and 1.5. In each pattern, the measured flexible direction is changed in two directions . The results are different from the ones for parallel triangular arrays, and they are similar to the ones for square arrays.

When wind flows through the slats of a window blind, self-excited vibration sometimes occurs, which generates a high frequency noise. We have attempted to use this phenomenon to generate electricity. This paper reports our investigation of the effects of a diffuser which is attached to power generator. It was shown clearly in the experiment and the simulation that wind velocity becomes faster by a diffuser. According to this effect, a production of electricity increases at low wind velocity.

Some hydraulic turbines sometimes have severe flow-induced vibrations on their vanes. One is the torsional vibration of the stay vane. This vibration occurred despite the stay vane profile was selected to avoid generating large Karman vortex. This vibration was influenced by the guide vane. In this paper, the effects of the attack angle of the downstream vane on the torsional vibration of the upstream vane were examined by about 1/20 scale stay vane experimental equipment. First, the relationships between the attack angle of vanes and the limit of the reduced flow velocity inducing the torsional vibration of the upstream vane were examined. The large torsional vibration of the upstream vane did not occurred without downstream vane. But, the large torsional vibration occurred when the reduced flow velocity exceeds a critical value with the downstream vane. It was substantiated the limit of the reduced flow velocities were 1.5 and 3.0. The large vibration was only generated under a specific velocity range. The dominant torsional vibration frequency slightly increased from 35Hz to 45Hz with the reduced flow velocity. When the attack angle of the upstream vane and the downstream vane were series along streamline, the vibration became large. Next, the torque coefficient and Strouhal number of the upstream vane were evaluated. The torque coefficient for the upstream vane attack angle with the downstream vane was positive. This result showed the upstream vane will occur. And, Strouhal number was 0.35 at the reduced flow velocity 3.0. Strouhal number is near to 0.3 which is result of the previous study of stay vane. There is a possible of the generating vortex.

Faculty of Engineering Yamaguchi continues the examination for students who study Engineering in the universities, EMaT, collaborating with the Faculty of Engineering Hiroshima University. The examination is open to all universities in Japan and has gained high estimate from many people in Japan concerning with the engineering education. The present paper describes the important information to people in the engineering education. It includes various matters about the examination.

In an increasingly globalized society, communicative competence in English is becoming more important for university graduates. Nevertheless, it has been argued that Japanese engineering students' inward attitudes toward English studies persist. This paper documents the challenges and strategies employed in an effort to cultivate engineering students' learner autonomy in English studies and their positive outcomes under the five-year national project Go Global Japan. First, a series of implemented measures such as certification of selected first year engineering students who hold TOEIC450 or more will be explored. We will then move on to discuss a practical English curriculum entitled Technical Communication (TC): courses specifically designed for elite engineering student. These courses are aimed at producing students who hold TOEIC650 or more by their graduation from undergraduate courses. It should be noted that TC courses are entirely elective. Therefore, it was vitally important to encourage students to enroll in the courses on continuous basis. Finally, positive outcomes of the project will be demonstrated and analyzed. The three-and-a-half-year endeavor of the project generated a steady increase of certified selected engineering students, accredited students in TC courses, and fourth year students who accomplished TOEIC650 year on year. It can be concluded that engineering students' learner autonomy in English studies was enhanced as a result of the project.

There seem two major streams with respect to the higher education (university education) in the world, namely an educational system in the US and a system found in EU countries. In the present report, it is attempted to summarize the recent trends of higher educational system in EU. The Bologna Process and ECTS are introduced, and recent trends observed in Finland is summarized. As an example in engineering education, the merger of three universities including Helsinki University of Technology is explained. Although Finland is not a large country with only 5.4 millions in population, their efforts are quite informative to the universities in Japan from the aspect of globalization and rapid measure to the changes surrounding universities.

This paper presents on educational design of the static inverse-FF (feed forward)+PID-FB (feed back) control system for the static and dynamic property model. A pending down AW (from air to water) coil type heat exchanger is selected as an example of statics and dynamics of the object model. A semi-closed control syatem was constructed.

This paper presents on vibration transfer gain decreasing at low frequency area for a 2 inertia of seismic stage by a MR dumper and early virtual experiments including decomposition of building blocks in a connected twin buildings.

An educational tool using a microcomputer was developed for “Mechanical Engineering Seminar” in curriculum of Department of Mechanical Engineering, Saitama University. The tool was designed for a theme included in the seminar. An opportunity to be trained with the theme can be provided to third grade students at the department. Through the theme, they can learn assembling a computer, basic programing, serial communication setting, timer function, analogue-digital conversion and driving LEDs.

This study proposes a novel collection method of cell suspension using acoustic radiation pressure. The method enables to collect rabbit cornea cells by a pumping system using acoustic radiation pressure. To confirm our concept, we fabricated the pumping system composed of a reusable cell cultivation device with piezoelectric ceramic disc to generate acoustic radiation pressure, and a peripheral equipment to collect cell suspension, such as a pipe. The concentration of the suspension collected by the pumping system was comparable to the conventional method, pipetting. Furthermore, we counted the number of cells that were cultured for 72 h after collected by either proposed or conventional collection method, in order to compare the cell proliferation. As a result, the cells collected by the developed pumping system had higher proliferative ability than that of cells collected by the conventional method. This suggests that cell aggregations, often appear in the suspension, were removed through a small gap between the culture surface and the pipe end. As a result, cells could be cultured efficiently. The proposed cell collection method can be a promising cell collection method for cell culturing process.

This paper describes the mechanism of cell proliferation promotion by mechanical vibration focusing on an integrin. Integrins are transmembrane receptors that are the bridges for cell-extracellular matrix interactions and related to cell proliferation and differentiation. Integrin α5β is the primary receptor for fibronectin which exists in extracellular matrices. If integrin α5β is a mechanosensor of mechanical vibration, cells lacking β1 integrin subunit are insensitive to mechanical vibration and their cell proliferation is not promoted by vibration although its promotion was reported in the conventional studies of osteoblast-like cells. Here we show the effects of mechanical vibration on GD25 which is a fibroblast-like cell lacking β1 integrin subunit. When GD25 cells were cultured under the mechanical vibration of 0.5 G and 12.5 Hz, the saturated cell density was significantly higher than the control group although β1 integrin subunit was lacked from GD25 cells. The multilayer formation of GD25 cells was observed by fluorescent microscopy and the number of the layer in the vibration group was higher than that in the control group. This indicates that the cell proliferation promotion under mechanical vibration may be related to the multilayer formation.

It is known that living bodies consist of many cells and that each cell senses environmental changes as mechanical stimuli. In most researches related to a cell mechanosensing system, static stimuli are applied as mechanical stimuli in experiments. On the other hand, it was reported that osteoblasts also responded to mechanical vibration as dynamical stimuli. In this reaction, biochemical response of cells has maximum value under mechanical vibration of a certain frequency. This phenomenon has analogy with resonance phenomena in the vibration engineering field. Therefore, we considered that cells have natural frequencies and modes of vibration because cytoskeletons have stiffness and that deforming cellular structures under mechanical vibration is in relation to cell mechanosensors. Here we show a novel method to observe a living cell under mechanical vibration. We focused on nuclei and actin filaments as cellular structures and investigated the existence of modes of vibration of a cell by fluorescently labelling and visualizing it. Mechanical vibration was applied to living cells by an exciter. Videos were taken by a high speed and high sensitive camera. The phase difference between the movement of a cell and an exciter was measured to find natural frequencies.

We proposed a method of deformability evaluation based on the deformation and movement by the dynamic behavior of erythrocytes in the oscillation flow field. However, to evaluate the deformability of variously changing erythrocytes according to the individuals and disease state was considered necessary to improve the accuracy of the model.Therefore, we examined the degree of freedom and the mass ratio of the mathematical model for the purpose of improving the accuracy of the modelin the previous study.Simulation based on the parameter identification resulted that the viscoelastic 2 elements with 3 degree of freedom model with particular mass ratio became waveform close to the erythrocyte's deformation amount ⊿L of experimental results．However, the improvement of the phase shift of the erythrocyte -e's center of gravity displacement ⊿G had a limit．Also, the viscoelastic 3 elements with 4 degree of freedom model was found that the phase shift of erythrocyte's center of gra -vity displacement ⊿G between experimental result and simulation result is eliminated．However, the erythrocyte's deformation amount ⊿L has become monotonous in this model as compared to the previous study．From the above，it improve -ed the accuracy of the viscoelastic 2 elements with 2 degree of freedom model in previous study．

Diffuse axonal injury (DAI) is caused by sudden inertial loading to the head associated with rapid deformation of brain tissue, resulting in the stretching of neural axons. Periodic swellings along axons and axonal bulbs at disconnected terminal ends of axons that are the morphological hallmarks of DAI pathology lead to the disconnection of neurons from tissues, resulting in cell death. The β-amyloid precursor protein (β-APP) that is conveyed by axonal transport and Tau protein that is associated with axonal microtubules accumulate where axonal transport is disrupted. In this study, the cultured rat brain neuronal cells were stretched to strains of 0.10–0.30 at strain rates of 4–50 s^-1 . The sham control is put in the stretching device without mechanical loading and then is incubated under conditions of 5% CO² and 100% humidity at 37°C. β-APP and Tau protein were stained at 3 h post-loading and observed using fluorescence microscopy. As a result, β-APP and Tau protein accumulated in swellings and bulbs following stretching and accumulated axons significantly increased following strains of more than 0.22 in a strain-dependent manner compared to sham control. However, there were slight changes with regards to the dependence of strain rates. These results suggest that the threshold of interruption of axonal transport is 0.22 strain.