In this study, we devised an active device which is used to suppress the essential tremor in human limb. The tremor can be observed in most human arms under excessive stress or chills, even he/she is at physically well condition. Therefore, the tremor may cause anyone a bad effect on precise operation, e.g. welding and surgery. In this work, experiments are performed where the simulated microscopic surgery is imposed on subjects whose fingers are equipped with the active mass damper attenuating the tremor in their hands. The damper is actively driven according to Single-frequency Adaptive Notch flilter and the state feedback controller designed according to the linear two-degrees-of-freedom vibration system model. Subjects were asked to grip a needle having a relatively small diameter using tweezers, and were also asked to insert it in a needle with a larger diameter. Tremors were measured while the subjects kept the tip of the needle in place. The damper was shown to be effective for attenuating vibration in human fingers.

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In this study, to achieve a human-adaptive noise and vibration design in a vehicle cabin based on the sensory characteristics of the passengers, the psychological stress of the occupant by the vibration of the seat are studied. First, the measurement of the vibrational acceleration and its modal analysis of the seat and its occupant were performed. Results showed that the seat vibrated in the direction in which the seat and back rest overlapped due to the vibration of the frequency consistent with the second order vibration of the engine. Further, it was found that the occupant's head vibrated in the front and rear direction in opposite phases with respect to the neck and torso due to the vibration of the second order vibration of the engine. It was also revealed that the left and right sides of the thigh vibrated in opposite phases, and the left and right sides of the knee vibrated in the same phase in the vertical direction. Next, the brain waves of the occupant were measured when the vehicle was an idle state. Results showed that there was a clear difference of the intensity of the alpha-wave in the idle state, which proved to be useful for judging the stressed and relaxed state of the occupant.

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Viscoelastic materials are used as damping materials. In recent years, vibration response increase due to miniaturization and weight reduction of machines and structures, and the vibration and noise tend to increase. Viscoelastic material/particle composite is focused on because damping material is required the performance which enhance in certain frequency band. However there is not clear the relationship between damping characteristics and compounding condition. The purpose of this study is to simulate the damping mechanism of natural rubber/particle composites using the distinct element method. We examine the validity of the model with only natural rubber and with natural rubber blending fibrous fiber particles. As a result, it is possible to reproduce the increase of the loss factor due to the friction between the rubber and the fiber particle. The increment of the loss factor can be reproduced by considering the friction.

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In this study, we created an acoustic metamaterial that can reproduce the peculiar sound propagation characteristic, and examined the change of the deflection characteristic of the sound wave by the difference of the internal structure pattern of the material. To give a sound speed gradient inside the metamaterial, we devised an acoustic metamaterial with a certain path difference inside. It was clarified numerically and experimentally that the transmitted sound could be deflected by using the proposed acoustic metamaterial structure, succeeding in deflecting a broadband (500 Hz to 4kHz) sound.

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The aviation industry is required to produce and operate an environmentally friendly aircraft. One of challenging issues is the noise reduction. One solution is an acoustic liner.It is required to investigate the influence of flow to acoustic liner. In this study, we performed aeroacoustics analysis of simplified acoustic liner model consist of three resonators using Cartesian-mesh CFD. Three incident sound pressure is set to investigate the influence of the sound power to acoustic liner. According to the computational result, high incident sound pressure affects the flows in the resonator.

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In this study, an experimental study on the difference of the playing sound of the electric guitar caused by the difference of the material of its component part was conducted. We changed the material of the pickguard of the electric guitar from the plastic one which is commonly used to the copper one. In the experiments, simultaneous measurements of the vibrational acceleration of its peg, pickguard, and the output voltage of the guitar with a constant plucking force of the strings were performed. It was found that the profile of the RMS value of the vibrational acceleration on the pickguard changed when the copper pickguard was used. In addition, the vibrational modes of the pickguard also became quite different ones by using the copper pickguard. In conclusion, it was determined that the sound quality is affected by the vibrational characteristics; these can be adjusted by varying the means by which the pickguard is attached to the guitar body.

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A tire is one of important mechanical elements of automobile, which is developed with the prediction of the friction in the design process. However, it is quite difficult due to the complicated mechanism of generation of actual friction force. Though experiments are the more reliable than numerical analysis in the process, the friction performance in various conditions should be considered for the development. In this study, multiscale analysis proposed by the previous study is extended and applied to evaluate the friction of the rubber which is treated as component of the tire. The effect of the road amplitude is considered in the present method, which was not evaluated in the previous study. As result, the deformation characteristics are modified with the change of the sliding velocity, pressure and the road amplitude. The methodology and result can be extended to analyze the actual tire friction.

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An experimental study on the flow-induced noise from a flag was performed using a low-noise wind tunnel. In the experiment, simultaneous measurements of the noise from the flag and its displacement were performed and their relations were discussed. Experimental results showed that a highly periodic flow-induced noise that had strong directivity in the vertical direction was generated from the flag and its Strouhal number based on the streamwise length of the flag had a constant value. In addition, it was shown that the noise source of the periodic noise was the center of the trailing edge of the flag from the results of displacement measurements.

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The effects of expansion ratio and Reynolds number on backward-facing step flow are investigated experimentally. The expansion ratio ER is changed to 1.5, 1.75 and 2.0, and the Reynolds number based on the mean velocity and the hydraulic diameter of inlet channel ranges from 1.5 × 10³ to 6.0 × 10³ . The Reynolds number range includes laminar, transition and turbulent flows. The forward flow fraction γ and local skin friction factor C_f are measured using a micro flow sensor. In the laminar region, the distributions of γ, C_f and wall static pressure change greatly between ER = 1.5 and ER = 1.75. In the turbulent region, there is no significant difference in these distributions even if the ER is different. The reattachment length non-dimensionalized at the step height decreases when the flow upstream of the step transitions from the laminar to the turbulent, and is minimized when ER = 2.

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