The evaluation methodologies for the flow-induced vibration of an elastic beam subjected to an axial flow in confined narrow passage are reported. One of authors has already proposed an analytical method using the Navier-Stokes equation for the dynamic stability of an elastic beam subjected to an axial flow confined in a narrow passage. In this paper, by using the proposed analytical methods, the numerical studies are performed taking three kinds of support conditions as parameters, that is, a cantilever fixed at the upstream side, a cantilever fixed at the downstream side, and a simple support beam at the both sides, respectively. Moreover, the parameter-studies are also performed concerning with a width of annular gap, viscosity of a fluid, and structural damping. And the effects of support conditions of a structure, structural damping, and fluid characteristics on the dynamic stability of an elastic beam due to an axial flow confined in a narrow passage are clarified for proposing a safety dynamic design guideline concerning axial flow-induced vibrations in industries.

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In this paper, in order to investigate a contact area between the measured profile of wheel and the designed shape of rail, we carried out calculation of the contact area strictly by a general software program, which applied the boundary element method and half-infinite body approximation. In addition, a calculation method of a creep coefficient is proposed with focus on contact areas between actual wheel and rail. Moreover, we also carried out numerical simulation of the running stability to find out how the difference of a value of an estimated creep coefficient has influence on the running stability of railway vehicle. As a result, it is shown that the contact area between the actual wheel and the rail has the shape composed of many contact areas, and the estimated creep coefficient may be smaller than the Kalker's theoretical value due to the influence of fine unevenness of wheel tread. Furthermore, we describes that the proposed method make the evaluation on running stability on the safety side.

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Centrifugal pendulum vibration absorbers are widely used as a vibration suppression device for helicopters. The vibration characteristics of this absorber have been investigated by utilizing linear anti-resonance theory. However, it has been noted that nonlinear characteristics appear when pendulums swing at large amplitudes. The authors investigated vibration suppression characteristics of pendulum absorbers considering nonlinear characteristics of pendulums. In the first report, we investigated a two-degree-of-freedom (2DOF) system composed of a rigid blade and a pendulum. In this system, the blade was excited by a harmonic deflection motion of the shaft. In the second report, we investigated a three-degree-of-freedom system composed of a fuselage, a rigid blade and a pendulum. In this third study, the model has 3DOF and is composed of a blade, a pendulum and a rotor mount. The blade is assumed to be flexible and only the first elastic mode is considered. An aerodynamic excitation force is applied to the blade. The vibration suppression characteristics of this system are investigated theoretically and experimentally.

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Passive biped walkers can walk down a shallow slope without actuators. This study presents a simple planar passive biped walker with flat feet and ankle springs and investigates the effect of torsional spring stiffness on the pitch motion at the ankle joints. Numerical stability studies indicated that the motion of the passive walker is stable. The physical biped walker has four legs, with each of the two legs connected so that they move identically in order to restrict the motion of the walker to the sagittal plane. Experimental results showed that the biped walker can walk in a stable manner.

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Tripod constant velocity joints are used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To determine the mechanisms inducing the thrust force, a detailed model is constructed based on a multibody dynamics approach. Although the joint is equipped with three rollers and grooves, this model consists of the principal parts for one roller and groove in order to precisely analyze frictional phenomena occurring between the roller and the groove. These principal parts are defined as rigid bodies and are connected by force elements of contact and friction. The appropriateness of this model is verified by comparing computational and experimental results and it is clarified that the principal factors inducing the thrust force are three kinds of sliding friction force at the point of contact between the roller and the groove. This paper also describes the reason why the third rotating order component of the thrust force is induced by one roller and groove.

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A theoretical analysis model is presented to investigate the nonlinear dynamic behavior of bump-type foil bearings, i.e., the instability and unbalance response. In the developed model, the foil structure of bump-type foil bearings was simulated using the link-spring model, which was presented and validated in a previous study. During the calculation, the Reynolds equation and the foil structure model were coupled though the pressure and film thickness. An iteration solution method with the equation of shaft motion was applied for the shaft orbit. Parametric studies of design parameters, such as the bump number, the length ratio of the segment between two bumps and a bump, the foil thickness, the bump height, and the Young's Modulus, were presented upon the analysis of static performance and the instability of bump-type foil bearings. It is noted that more bumps or lager length ratio lead to larger load capacity. But the bearing load capacity does not change with different bump heights. Moreover, the threshold speed of instability decreases significantly with the rise of the bump number, especially when the number of bumps is low. However, it almost does not affect by other four parameters.

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Collision Mitigation Brake (CMB) is a part of the Pre-crash safety system intended to mitigate damage during vehicle collisions. In this study, the effects of CMB system on vehicle rear-end collision accidents were investigated. To this end, a dynamic vehicle simulation model was constructed, in which the sensor and the CMB model were built. By using this model, the reduction of collision speed by the CMB system was evaluated numerically. Here, the road surface friction coefficient is considered to have a large influence on the CMB. In addition, the Time to Collision (TTC) which is the judgment line of the brake initiation is the key factor to the efficient operation of CMB. Therefore, simulations were carried out on road surfaces with different friction coefficient and CMB system with different values of TTC. Generally, the effect of CMB is expected to increase with the rise of friction coefficient of the road and the value of TTC. A larger value of TTC will be preferred for the cases of roads with low friction coefficients. However, collision avoidances might occur when the large value of TTC is employed in low speed collisions. Finally, the findings revealed that the value of TTC should be controlled in such that the value is increased for roads with low friction coefficient and decreased for low speed collisions.

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Lately, ecological and intelligent colloidal dampers based on the liquid penetration/exudation in/from lyophobic nanoporous solids were proposed. Although colloidal dampers could be attractive for various applications, they are still under research, since some unexpected findings await satisfactory explanation. For instance, colloidal dampers are able to dissipate large amounts of mechanical energy without significant heating, and such result is surprising since traditional absorbers transform almost integrally the dissipated energy into heat. In this work, using a digital infrared-camera, the temperature distribution on the external surface of a colloidal damper is recorded versus the working time and the positions of the main heat sources are identified. Such experiments allow evaluation of the temperature inside the colloidal damper's working cylinder and the absorber's generated heat. Introducing the colloidal damper inside of an incubator, variation of the hysteresis shape and dissipated energy versus the working temperature can be found. From such experimental results, ratio of the generated heat to the dissipated energy is evaluated.

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When signing for tracked vehicles, which are operated on unpaved roads or soft ground, the interaction between machine and soil must be analyzed. In this research, attention was focused on the interaction under front idler, that is, traction soil by a grouser in driving system. To verify the validity of interaction analysis between a grouser and soil by using 3D DEM soil model, traction simulations and experiments were carried out. In addition, the soil model was considered particle roughness to introduce compaction effect by compression. To check the effectiveness of the soil model, compression test and shearing test were conducted. Consequently, soil behavior and porosity change were found on the tests. And comparing the results of traction simulations and experiments, soil behavior and qualitative characteristics of traction resistance were conformed. Therefore, interaction between grouser and soil could be analyzed by using the soil model considering particle roughness.

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A damping device for electric railway poles has been invented in order to reduce vibration in overhead contact lines caused by earthquakes or passing trains. The authors conducted theoretical analyses on poles equipped with the damping device and vibration tests on full scale poles. The damping device is a sandwich structure consisting of several steel plates and viscoelastic sheets and has a damping effect even for minute displacement. It has been confirmed that the theoretical results are almost identical to results of vibration tests on actual steel-pipe pole. Vibration tests also demonstrated that the damping device increases the loss factor ten-fold in comparison to a simple steel-pipe pole. In vibration tests on a concrete pole, the damping device reduces the maximum bending moment by approximately one half in comparison to a simple concrete pole.

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A novel remote-control method for micro vehicles based on two-way laser communication is proposed. The vehicle receives operational commands in the frequency changes of a pulsed-laser. The laser also plays a role in tracking the vehicle by following the position of a corner-cube reflector equipped on the vehicle. At the same time, the vehicle returns information by means of a MEMS mirror equipped on the vehicle; the mirror transmits information as frequency changes in the light-path vibrations of the reflected laser-beam. The advantage of this system is that the all of these communication functions are achieved by a single laser beam; and the proposed method will contribute to simplify the mechanism and reduce the weight of micro vehicles. An experiment with a small wheeled-vehicle was conducted, and the results show that the concept exhibits a sufficiently accurate performance to control micro vehicles.

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In the present paper, we use time series data and fuzzy inference to identify individual differences in the behavior and proficiency of human operators performing various skills and use the identified individual skills as a fuzzy controller. Human operators are trained to a certain skill level at stabilizing an inverted pendulum, and the data obtained in 10 trials per operator were successively used for analysis, where the waveforms of pendulum angle and cart displacement were analyzed. The maximum Lyapunov exponents were estimated from time series data with respect to embedding dimensions. The fuzzy controller identified from the time series data for each trial and for each operator represented well the human-generated decision-making characteristics, exhibiting chaos and a large amount of disorder The estimated degree of freedom of motion increases and the estimated amount of disorder decreases with the increase in proficiency, both in the experiment and in the fuzzy control simulation. It is also revealed that the agreement between the experiment and the fuzzy control simulation for the degree of freedom of motion and indicates that the entropy ratio is particularly good when the measured waveform and the simulated waveform are similar in appearance.

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A squeal test using a pad with a different thickness demonstrated that a squeal with a higher frequency can be generated if a thin pad is used. The factors that changed as a result of pad thickness were termed 'difference of pad rigidity' and 'dimension difference in the thickness direction of the pad,' and the influence each factor exerted on the squeal was clarified. First, the dynamic stiffness of the pads used for the squeal tests were measured by adding a vibration that imitated the frequency and amplitude of the squeal. The measurement showed that the pad rigidity becomes hard when the pad thickness becomes thin. In addition, the pad vibrated with the same amplitude and the same phase from the frictional contact surface to the back plate in the thickness direction. The pad rigidity is in inverse proportion to the pad thickness because the pad can be viewed as springs in series in the thickness direction. Next, the influence that pad thickness exerted on squeal was analyzed by using a surface-contact-analysis model that reproduced the pad rigidity with a distributed spring and the dimension difference in the thickness direction of the pad with distance from the contact surface to the rotational center of the pad. Results showed that the squeal frequency becomes high when the pad rigidity becomes hard. If the dimension in the thickness direction of the pad becomes small, the squeal is not generated easily; however, the dimension does not influence the squeal frequency.

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KUKAI is a pico-satellite developed by Kagawa University and was launched by the H-IIA rocket by the Japan Aerospace Exploration Agency (JAXA) on 23 January 2009. The primary objective of KUKAI is technical verification of a tethered space robot, which is a new type of space robot system proposed in previous work. KUKAI consists of mother and daughter satellites for tether deployment. This was the first time to launch mother-daughter satellite among pico-satellites less than 10kg in the world. Then, it is important to develop separation mechanism. The separation and the launch lock mechanisms for KUKAI have been developed, and confirmed and evaluated by launch environment and microgravity condition. As the launch result, KUKAI was separated from the rocket as planned, the system started normally, and deployment of the solar paddle and the antenna was succeeded.

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