This paper proposes a method improving accuracy offeree identification and contribution analysis in Transfer Path Analysis (TPA), which is a key technology for solving the noise and vibration problems. The Matrix Inversion Method, which is a conventional approach for force identification, is needed to have much accuracy. Improvement of accuracy of force identification is important because it influences the result of TPA. A new force identification method by using Apparent-Mass Matrix has been recently proposed, which provides more accurate results than the Matrix Inversion Method. On the other hand, it is understood that the Apparent-Mass Matrix Method sometimes gives less accurate result than conventional approach for the contribution analysis. Therefore, this paper proposes a new approach for estimating Frequency Response Function (FRF) used in matrix inversion method, by using driving signal for exciter in vibration tests as a reference. The method estimates accelerance matrix from two sets of FRF matrices; one between driving signals and forces, and the other between driving signals and accelerations. A numerical simulation and a vibration test are conducted to compare the results by the proposed method with the conventional approach.

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In this paper the authors present a new identification method that can accurately obtain all parameters of the rigid-body property of various complex structural objects whose first resonance will be higher than approximately 20Hz. The key technical points of the method are to refer only the natural frequencies of test object under some differently designed boundary conditions, and to fit those between the measurement and theoretical ones. The idea has been submitted to Japanese patent and PCT (Patent Cooperation Treaty) by Tokyo Institute of Technology. Then, a new German venture company Resonic GmbH was founded in February 2011 and has started its technical business and development of various sized systems with obtaining the monopoly of using the patent. The measurement accuracy will be expected very high so that the error will be less than 1%. The method has already been shaped as an automatic system. Ones are just required to put an object of interest on the measurement platform of the system and to switch on the system. The concept of the algorithm and a basic investigation regarding the identification accuracy are presented in this paper.

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This paper proposes a method of a non-contact experimental vibration analysis for underwater structures by pulsed-laser ablation. The impact testing with impulse hammer is used widely for vibration analysis due to the simplicity of the apparatus. However, the impact testing has limitations in use in underwater condition because of contact method by the experimenter. The proposed method yields the frequency response functions by applying a pulsed-laser-ablation-excitation force to the structure and measuring the output using a Laser Doppler Vibrometer. Since the direction, strength and effective duration of the pulsed-laser-ablation force are essentially constant, this force can be calibrated by measuring these properties in advance. Therefore input-detection-free frequency response function measurements can be realized. The method is validated by comparing FRFs obtained using laser excitation with ITEM. Additionally, the FRF obtained in underwater conditions shows that the natural frequency decreases and the amplitude is attenuated by comparing with FRF in air conditions.

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In the experimental modal analysis, the treatment device has to be fixed on the target structure in order to obtain the vibration response to the moment excitation. However, if the treatment device is used, the vibration property must be changed because of the additional mass of the device. Hence, it is difficult to obtain the accurate vibration response to the moment excitation. A moment excitation device that a step moment can be impacted on the structure without using treatment device was proposed. The proposed device is easy to handle and realizes the accurate measurement without additional weight. But, in this way, excitation frequency is limited to the low frequency band. In this study, a new moment excitation device that a impulse moment can be impacted on the structure is proposed. First of all, the principle of the proposed device is shown. Then, the experimental results are shown to confirm the validity of the proposed technique.

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For the forced excitation of a large structure such as airplanes using one actuator, natural vibration mode cannot be excited because the vibration doesn't spread in the entire structure. On the other hand, when a lot of actuator is used, the excitation frequencies of the actuators must coincide and the magnitude and phase of the excitation force must be minutely adjusted for every vibration mode. Thus, we used a method for driving at resonance point by using the self-excited vibration generated by the local feedback control that an excitation point corresponds to a vibration detection point. The excitation target is a laminar structure modeled on an airplane. The sixth mode is excited by using sixteen voice coil motors with the local feedback controller. The self-excited vibration has a number of natural vibration modes when self-excited vibration is switched on by adding a wave signal within the local feedback controller. So a stable desired mode of vibration can be excited by adding cross feedback controller.

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This study is concerned with cluster control for suppressing the acoustic power of the plate with asymmetric boundary conditions by controlling the element of vibration which contributes to the noise radiation. The conventional cluster control is based on the assumption that a target rectangular plate has symmetric boundary conditions. In this method, simple signal processing can be achieved by using symmetric property of mode shapes, and hence it is difficult to apply this method to the case in which the panel has asymmetric mode shapes. To cope with this problem, this paper proposes the application of the cluster control to the panel with asymmetric boundary conditions.

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This paper is concerned with sound insulating control by vibration insulation of a multiple-wall structure. A multiple-wall structure is composed of more than two uniformed panels separated by enclosed air gaps. The research model is supposed the multiple-wall structure is subjected to and got through by the acoustic sound. The objective of this research is to improve the sound insulation effect of this structure in a viewpoint of active control. For the improvement, the coupling terms between a plate subjected disturbance force and plates situated next to it are suppressed by feedback control force given from the reciprocal vibration. In consequence, the vibration insulation is accomplished and the vibration is localized in a target component. In this paper, first, the mechanisms of the multiple-wall structure vibration are revealed by modal coupling theory, and from it the coupling terms are check out. Next, the vibration insulation control by suppressing the terms is offered to. In the final, the performance of this novel sound control theory is demonstrated by the numerical analyses.

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This paper proposes a method of low-frequency noise reduction using piezoelectric elements. The piezoelectric element on the plate with an inductance and a resistance works like a mechanical dynamic vibration absorber. Using this plate, low-frequency noise was reduced. Optimum values of the inductance and resistance were theoretically derived, and their effectiveness was investigated through simulations and experiments.

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In the present study, we consider a cylindrical structure with thin plate at both ends and investigate vibroacousitc coupling between the plate vibrations and internal sound field when an external harmonic force is applied to one end plate, regarding such a coupling phenomena as one of the available measures to amplify acoustic energy. This coupling is theoretically and experimentally investigated by considering the behavior of both plates and the acoustic characteristics of the internal sound field for varying and the cylinder length. In the analytical model, the end plates are supported circumferentially by springs in order to obtain support conditions that are as close as possible to the actual condition in the experiment due to adjustments of spring stiffnesses. The coupling phenomena are estimated theoretically from the relationships between characteristics of the plate vibrations and the sound field with respect to some vibration modes. These theoretically results are verified experimentally through an excitation experiment using an experimental apparatus that is emulated by the analytical model. Moreover, the experiment of electricity generation demonstrates that the coupling phenomena are the available measure to amplify energy of the systems and to extract that, performed with piezoelectric elements.

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This paper presents a global active noise control method for three-dimensional acoustic field that compensates these disadvantages. Parametric Array Loudspeaker (PAL) in which multiple ultrasonic transducers are placed concentrically is introduced as the control sound source. Driving the ultrasonic transducers with proper time delays, the control sound source produces the wavefront similar to the noise away from the noise source. Superposing the control sound on the original noise sound, and suppressing the sound pressure at the error sensor, sound pressure is suppressed over a wide area around the error sensor. Compared with the case of using a ordinary speaker as the control sources, the validity of the proposed method is clarified.

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The scanning method of Acoustic Holography is used to identify the location of stationary sources. If measurement of unstationary sound source, it needs a lot of microphone. The method is microphone array method. However, this method is very expensive. This time, tried to measure the unstationary sound by devising the scanning method. In the experiment, using the linear slider for stepping motor. This motor will continue to reciprocate given interval. By applying to trigger function, it could be measured the sound pressure of moved the moment. Analysis of sound pressure used the Nearfield Acoustic Holography (NAH) Method. As a sound source localization method, the acoustic Intensity (AI) method is widely used. But the accuracy of NAH is better than that of AI method. As a result, a high frequency have been able to identify the location in the sound source, but a low frequency have not been able to identify the location.

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In order to apply acoustic energy to industrial fields, its amplification is essential and vibroacoustic coupling is one of best ways of amplifying acoustic energy. The present paper describes vibroacoustic coupling between the plate vibrations and the internal sound fields of a cylindrical structure connected two cylinders with thin plates, and the coupling phenomena are investigated theoretically and experimentally by considering the behavior of the plates and the acoustic characteristics of the internal sound fields with variations in the cylinder length, when an external harmonic force is applied to one end plate. The acoustic characteristics are evaluated based on the sound pressure level, which is maximized while changing the phase difference between the plate vibrations. The behavior of the plate vibration is investigated by varying the phase difference with the cylinder length. Moreover, the experiment of electricity generation is carried out with piezoelectric elements, which are installed on the plates. These results reveal that vibroacoustic coupling is effective in increasing the acoustic energy and can extract the acoustic energy via the plate vibrations.

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Sound quality of impact sound becomes important in design of golf club. In this paper, four simple experiment models produced to examine the vibrational characteristic of the golf clubs. First, the results of the numerical analysis of the models and the results of the experiment are compared, and the effectiveness of the numerical model is shown. Then, confirmed the effectiveness of the proposed method for estimating impact force. Finally, it is examined the influence that a structural change in the golf clubs give to the sound quality of the impact sound is predictable by use three sound quality parameters.

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In the research of the tone quality of a classic guitar, the control of the vibration modes on the surface board is important. The couple bending modes on the front and rear face cause the "glottal sound " which is unsuitable for the guitar sound. The high performance sensitive plate of guitar has the trouble for the quality. We give the damping treatment for the surface plate and got the good result.

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This paper describes a product quality check of micro fan vibration by using the fluctuation mechanism. The micro fans are used by many electronics equipment for cooling. It is essential for present industry. But, the micro fan has checked by surveyor who has experience skills which using their auditory organs and tactual sense. It is not easy that surveyor masters their skills, and large errors are produced by their mental and physical condition when they survey. Now, new evaluation and diagnosis method is needed. This study focuses to moving of surveyor's hands, and uses fluctuation mechanism simulated human handling. The experiment measured the acceleration of micro fan's vibration, and took the deviation between the acceleration overall maximum level and minimum. Their results show one of methods that make sure of the diagnosis of micro fan's vibration.

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Recently, significance of human-machine interface by voice recognition techniques has been increased. Actually those techniques have been adapted to robots, ubiquitous system, cellular phone, auto-translation system and so on. Recognition researches of meaning ingredient included in human voice have been carried out mainly. However, there are many problems about the specification of speaker. The former recognition methods such as STFT, FFT, LPC and cepstrum analysis have many problems on recognizing accurately meaning, speaker characteristics and emotion state of speaker because human voice is a transient signal. Therefore, this study adopts the wavelet analysis, which has been using widely to analyze transient signals on Time-Frequency domain. This study was performed to extract the fundamental frequency using discrete wavelet analysis due to adopt a continuous wavelet analysis for the transition, it was revealed that a determination can be made between individuals.

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This paper presents a new concept of actuators and bellows based on the rigid foldable cylinder discovered recently. Connelly et al proved that when a concave polyhedron is deformed, its volume remains constant in 1997. In spite of this rigorous mathematical theory, we have observed a real model of rigid polyhedral cylinder which changed volume substantially at some particular situation. Inspired with this phenomenon, we have identified that particular situation where the model, made of practical engineering material, can change its volume. This phenomenon is now applied to propose the new concept for actuators and bellows.

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