The authors have been developing power assisted hands for cervical spinal cord patients. The latest model (PA-Hand No.3) which assists patients to grasp the objects is of 500gf weight. This is still too heavy for patients to use comfortably in daily life. To reduce the weight, the authors replaced air actuators with artificial muscle actuators. The target of this study is to satisfy the following specifications; (1) Weight; under 150gf, (2) Function; three-finger pinching for small objects and grasping bottles of 500gf in weight. This paper firstly describes trial production before completing PA-Hand No.4. Several trials were made to complete the products by improving poor functioning. During this stage, several experiments were also conducted. The final product, PA-Hand No.4, satisfied the above specifications.

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This research describes a sheet shaped soft actuator that supports wrist's 2 DOF motion over the wide range. The system aimed at patients with one-sided paralysis by brain disease and orthopedic patients. A past actuator named WTA-band had the fault with a large resistance. Newly, the fluid actuator composed of a special tube and the cloth for the restraint is designed. It is based on the idea of decreasing resistance and expanding wrist's range of motion. ECSA was made by using the actuator. And Experiments showed that wearable actuator which is composed of 4 ECSA and a supporter has an ability to support wrist's 2 DOF motion. Finally, the effect was confirmed measuring the wrist's EMG.

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For preventing movement disorder the rehabilitation equipments were developed utilizing bellows actuators. The equipments for hand, leg and foot were produced and tested. The equipment was able to absorb the change in the distance between joints according to the change of the angle of the joint. Practical utility as rehabilitation equipment was proven experimentally.

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A power assist suit consisting of shoulders, arms, a back, a waist, hips and legs units was improved. In order to extend moving range of the power assist suit, new waist joint unit was developed. The person was able to squat more deeply by wearing the new power assist suit by improving the mechanism of the waist and the hip joints. The validity of the improved waist and hip units were proven experimentally.

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A current four-wheel walking assist device described the research and development of three-wheel type walking assist device that valued mobility, the cost, and the design. The result of the examination with four-wheel type walking assist device is made the best use of, and three-wheel type walking support machine that everyone where use easily will be developed

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For the elucidation of the problems concerned in dynamic load cell, the experiment was carried out using a produced load cell. The results showed the output values of the load cell increase as the sensor cross section of the load cell increases. This trend is due to the effect of multiple reflections in load measuring system, and that was certified by a wave propagation model which employed the impedance method. It was proved that the dynamic load cell cannot be utilized under the conditions where wave motion is generated in the system.

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Practically, it is very important to clarify the magnitude of stress and deflection of the beam subjected to an impact force. Although, many studies have been made from old, no practically useful equation has been ever found yet. There upon, loading experiments were carried out to investigate the dynamic behavior of the model beam with three sizes of span and height in the way of hitting the loading rod at the tip of which a rubber material is put on, by the knocking rod. It was revealed that the apparent static loads to produce equivalent deflections by the dynamic test are proportioned to -1 power of the span of the beam. It was also revealed the deflections are proportional power 2 of the span, and power -0.6 of the equivalent spring constants of the beam. According to the results of this study, it is possible to estimate the dynamic behavior of beams of different sizes of span and height through the test for a species of beam.

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In this paper, a strain sensing device using piezoelectric ceramics is developed to monitor the feature of strain history of structural member. The sensor is a rectangular box made of thin aluminum plate, in which piezoelectric element, electric circuit including charge amplifier, signal processing unit, and battery are facilitated. The sensor is bonded onto the structural member by using adhesive agent. In order to see the performance of the sensor, experiments are carried out using a fatigue testing machine. As the result, it is clarified that proposed strain sensing device can measure the fluctuating stress of structural member.

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内燃機関の燃焼状態を直接示すパラメータとして,一般に図示平均有効圧(Indicated mean effective pressure,以下IMEP)が用いられる.一方,IMEPを求めるために使用する指圧センサはデータ安定性やコスト,寿命などが課題となり実車制御用としての利用が難しかった.しかし,燃焼室外で燃焼に起因するエンジン振動やボルト軸力変化のような指圧波形関連信号を計測し,IMEPと相開性の強い等価IMEPをモニタする手法を使うことで有効活用が見込める.本研究では,指圧波形関連信号を圧電型点火プラグ座型力センサ(以下,供試センサ)によって検出し,等価IMEPを精度良く検出する手法を検討した.供試センサの特性を調べるため,脈動圧校正器による検定を行なった.供試センサは測定系の時定数を小さく設定すると出力波形にサグと呼ばれる電圧降下を生じ,従来から用いられている検定圧に対する出力波形振幅から感度を求める方法の適用が難しい.そこで,図A1のように,横軸に検定圧(基準センサ電圧),縦軸に供試センサ出力をとるスロープ法によって感度を求めた.また,チャージアンプの設定によって,感度や生じるサグの大きさに影響を与えることが確認された.実機エンジンで供試センサの出力波形を確認すると,電気的ノイズや機械的振動が重畳しているが,低周波数成分は比較用の指圧波形に近い波形がトレースされた.IMEPは指圧波形中の低次周波数成分で決定されるので,等価IMEP計測への適用が期待できる.実際に等価IMEPを求めると,供試センサによる等価IMEPと比較用指圧センサによるIMEPの相関係数は0.799となり,相関性はあるものの制御や高精度計測には相開性の向上が必要であった.そこで,チャージアンプや演算ゲートを適切に設定することで図A2のように相[figure]関係数を0.990へ向上させることができた.以上から,測定系や演算法の工夫することで,点火プラグ座型力センサを利用した,IMEPと相関性が高い等価IMEPの計測が可能になった.

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The natural gas market is activated, and flowing quantity and the calorie measurement of the gas supply are paid to attention in recent years. The system that can do with the ultrasonic flowmeter whose flowing quantity and calorie measurement are one is assumed to be hard, it renews, and it reports on the current state paid attention to again. (This product is the joint development with Osaka Gas Co., Ltd..)

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This paper proposes a vibration testing and health monitoring system based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface. It is possible to measure high frequency vibration responses in this system. A health monitoring system is constructed by this vibration testing system and damage detecting algorithm. A microscopic damage of structures can be extracted by detecting fluctuations of high frequency vibration response with this health monitoring system. Loosening of bolt tightening torques is defined as the damage of the system. The damage is detected by statistical evaluations with Recognition-Taguchi method.

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This paper presents the basic strategy of the development carried out in the VectorDynamics Corporation as the first report. This development is supported by JST. The paper contains (1) the fundamental problems of the current technologies using the accelerometers and gyros, (2) the examples of explicit and implicit discrepancies between the needs shown in the standards or regulations and the current technologies, (3) the development policies in VectorDynamics, (4) Brief explanation of theory, (5) brief introduction of the novel instrumentation for the multi-axis inertia sensor standardization.

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This paper deals with active acoustic enclosure for preventing vibration of the precision measuring equipment etc., e. g. AFM, due to surrounding sound noise. In our previous work, we have proposed active control method of transmitted sound power though a panel and have both theoretically and experimentally demonstrated the high performance of the method. In this study, the proposed method is applied to the acoustic enclosure experimentally. PVDF film is used as an error sensor to suppress the sound pressure in the whole area of the enclosure. The experimental results are shown, demonstrating the validity of the active acoustic enclosure.

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The present paper describes numerical and experimental investigations of characteristics of adaptive feedforward active control systems of beat noise in ducts. Dual-input, dual-controller and single-output (2-2-1) system has been proposed to improve the performance of the active control. The results show that convergence performance of the system is influenced by the step gain and frequency separation of tones. The step gain can be increased by increasing the frequency separation of tones. Furthermore, the results imply that the fastest convergence of the algorithm is obtained by the optimum step gain.

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On active noise control in 3-dimensional acoustic field, a control effect becomes worse when an evaluation point moves. Against this problem, we proposed control with filter map. Effectiveness of this algorithm was shown by simulations and experiments. However, this method needs large memory for accumulating FIR filters. Against the problem, adaptive algorithm is proposed. In the algorithm, IIR filters is used for reduction of memories. The filters are updated by using fast Kalman filter. The experiments is carried out in a box made by gypsum and wood. The result shows that high effectiveness of control and fast convergent speed can be obtained with little memory by proposed algorithm.

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In development of the noise control system arrayed the insulation panels, the noise that input to the noise control panel has been defined the plane wave. When the incident noise is random, the noise insulation panels are excited with distribution. A purpose of this study is establishment of an efficient control method that reduces the transmitted noise through some noise insulation panels with control. This paper described an outline of the control method and the results about a relation between the noise reduction effect and number of the noise insulation units of control.

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Recently, there exist great demand to develop a light insulation structure with large sound transmission loss. We have been developping an Active Sound Insulation Unit (ASIU) that consists of the Active Sound Insulation Cell (ASIC). Each ASIC is controlled as a SISO system. In the previous studies, we have developed an ASIC that consist of a flat speaker. In this paper, by changing the shape of the structure, we further try to develop an ASIC that is lighter and achieves better sound insulation performance.

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In an ordinary active noise control (ANC), an error microphone is settled in the control area but it can be an obstacle of human movement. We proposed Virtual Microphone System (VMS) that an error signal can be obtained from the error microphone settled out of the control area. We applied VMS to Active Sound Shielding and succeeded in the reduction of the noise. The effect of the reduction is approximately 16.4dB. We measured the sound pressure distribution in the control area and analyzed the acquired data in the octave band of 125Hz to 2kHz. From the measurement, an enough control effect was obtained in frequency bands of 250, 500, 1k and 2kHz.

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It is increasingly needed to reduce the noise in the interior of train cabin because it is demanded to have a comfortable riding for high speed trains while noise becomes greater as trains run faster. As for this problem, recently the noise control system with piezoelectric material has been noted because it makes it possible to reduce vibration and noise at high efficiency without adding great mass. In this paper we propose a new control method to improve the performance of this system by dividing the noise control panel into some control groups and controlling each group individually.

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This paper presents a new approach of active control of a window pane. This study can be applied to a window of a house or an office, producing a quite space in the adjacent room. To obtain a high performance of interruptive sound using a light weight material, the active vibration control of the material can be used to improve the transmission loss. The acoustic mode of the cavity greatly influences the window pane in the enclosure. Therefore, when applying vibration control of the structure, set up in the closed space, it is necessary to note the influence of the acoustic mode.

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産業用ディーゼルエンジンは噴射ポンプや動弁系のカム軸の駆動に歯車列を用いるため,無負荷運転時に負荷トルクが減少すると歯面分離による歯車のガタ打ちが発生する.さらにクランク軸振り振動が発生するとクランク軸歯車のガタ打ちが激しくなり,騒音が増大する.本報告では著者らが開発したクランク軸歯車列/エンジンブロック連成振動応答計算法に振りダンパーを追加し,クランク軸振り振動と歯車衝突力及び主軸受伝達力の関係を定量的に明らかにすると共に,振りダンパーが高周波数域の騒音を低減できることを確認した.

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One of noise issues with LCD TV is buzzing sound from internal parts vibrating and coming in contact with surrounding parts. This vibration is caused by transmitting of vibration from speakers to internal parts. The smaller vibration transmitting to internal parts is, the less chance they come in contact with surrounding parts there is. Therefore, predicting conditions in which less vibration may transmit, during the process of product designing, is effective to counter this buzzing sound issue. However, vibration model of speaker is represented by multi-degree freedom system formula and calculation requires extensive and complicated work. It may also be time consuming to reach an answer. This report explains our finding that vibration of speakers mounted in LCD TV can be represented by limited vibration model.

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This paper describes a noise reduction design of transient sound radiating from a thin plate structure excited by random impact forces. To reduce calculation costs in a structural modification, an optimization design of two stages is presented. In the first stage, a mode shape minimizing input power into the structure is searched. In the next stage, the structure of which mode shape approaches the searched mode shape is optimized. The shape of dimple adding on a thin plate is set as design variables and optimized. It is confirmed that the proposed optimization is effective for reduction of sound power.

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Prediction of the structure-borne noises has been a significant issue for railway viaduct, since it causes an excessive degree of noise attributable to vibrations of the structural members such as floor slab. Therefore, we have developed a new method to predict the structure-borne noises based on the analysis of flexure vibration of members of the structure expanded to the whole of structure, and tried to apply the method to the concrete viaduct with slab track. At present, we try to apply the foregoing method to the concrete viaduct with ballasted track, to predict successfully the structure-borne noises thereon.

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In this paper a modeling method of the seats is proposed applying the Blot theory to represent a seat made of a elastic frame covered with polyurethane foam, which shows both the structural and the acoustical characteristics. In this method a sub-structuring technique is utilized to cope with the frequency dependence of the physical properties inherent in poroelastic media such as polyurethane foam. It is demonstrated that the results calculated by the method can fully describe the measured characteristics.

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Automotive seat structures mainly include metal frames, porous materials and surface materials. There are two media (i.e. internal air and resin block) in the porous materials. By carrying out our model test, the porous materials had sound absorption for cavity resonance. And they also had damping effects for the structural resonance of the metal frame. Under an acoustic excitation, vibration amplitudes of the metal frame increased by attaching the porous materials. It's "an effect of a sail" of the resin block in the porous material, which increases vibration level of the seat metal frame by receiving sound pressure. We also observed the similar phenomena when a thin leather sheet is covered on the foam with the metal frame.

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When considering optimized design of panel with composite layer including porous material, we have to know the detail mechanism. In this paper, we studied radiaiton power from flat panel with composite layer by creating simple model using trasfer matrix method and wavefield transformation. We validated proposed model by comparing with FEM results. From an example of comparison between fiber type porous material and foam type, we clarified the different behavior of those materials, which is different vibration shape appeared at compsite layer surface due to lateral direction wave number dependent. The result shows some of possibility like leading different results of panel shape optimization in the case of with/without composite layer.

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In order to investigate the influence factors on HIC (Head Injury Criterion) score of attenuation materials used for playground, impact tests were carried out in accordance with ASTM. Four kinds of the commercial attenuation materials were employed for the tests. The apparatus is composed of the missile made from aluminum alloy with a mass of 4.6 kg and a tri-axial accelerometer. The higher the missile was dropped, the more HIC score increased. From the time-frequency analysis, it was obvious that HIC score depended on the natural frequency of the vibration system in collision between the missile and the attenuation material. There is sufficient evidence to suggest that the use of a simple vibration system with a nonlinear spring is beneficial to assess HIC score.

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The mechanism of fluctuating vibration in engine accessory drive belts is studied. By the geometric study, it was clarified that the fluctuating belt vibration has multiple spectral lines centering around natural frequency. Some spectral lines fold back at 0 Hz when they have negative frequency. And it is assumed that the belt vibration will maximize when the lines cross the natural frequency. In this report, by the multi-body-dynamics simulation, that assumption was verified. And we found that the belt vibration will maximize because of parametric vibration rather than the folding negative frequency element.

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This paper presents the analytical method to evaluate the impact force induced by piston slap considering the dynamic effect of motion and vibration of connecting rod, crank shaft and engine block. The inertia force of connecting rod in vertical , horizontal and rotational direction are taken into consideration and the effects of these inertia forces on the piston impact force are discussed comparing with the conventional simulation method of piston slap. Moreover, influences of piston slap force upon the vibration and main bearing impact force of crank shaft are examined.

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本研究では回転しているクランク軸/歯車列とエンジンブロックの連成振動応答並びに放射騒音予測法の精度向上のために,歯車噛合い部の衝突モデルの検討を行った.振り子を利用した弾性衝突振動装置を製作して衝突力波形を計測した結果,油膜がない弾性振動状態では衝突剛性評価にヘルツの接触理論が適用できることを確認した.また油膜を介した衝突試験では油膜がない場合に比べて衝突力が早く作用し始めるとともに衝突力のピークが減少することを明らかにした.油膜減衰と構造剛性の直列構造で衝突部をモデル化できることを計算で確認するとともに,エンジン振動応答の時刻歴計算を容易にするため,非線形の等価ばねと減衰の並列配置で油膜を介した衝突をモデル化することを提案し,実機計算に適用した.

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Our final target of this study is developing a simulation package for predicting the pressure pulsation inside pipe-system and its sound pressure near the end of automotive exhaust system. This paper reports on the modeling of each components of real automotive exhaust system under the air pulsation by air-blower is working in laboratory. Three kinds of fundamental element model in the characteristic method are considered to construct the models of each component. The comparison of pressure measured and calculated is carried out to improve the models both static and dynamic conditions.

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In this study, the practical method to locate the sound source positions on the noisy machinery is developed by use of the Nearfield Acoustic Holography (NAH). Generally, an actual machinery has a complicated shape combined several components spatially, so the source positions are distributed in the three dimensional field. It is proposed that a compact two-dimensional microphone array is moved and located around the source, and the reconstructed images are derived at each measurement position as the different view angles by the NAH modified due to the small measurement aperture. It is shown that the proposed methods are verified experimentally.

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In this study, a virtual sound production system is developed where the difference frequency component appears as the secondary audible sound at a point of interference locally by the nonlinear interaction of two independently radiated ultrasounds while they travel directionally and intersect each other. The design of high-directive ultrasonic radiator, followed by the investigation of virtual sound production performance has been done theoretically as well as experimentally.

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This paper describes the improvement of the active control of machinery noise to comfortable sound referred to insect's singing. In order to increase the resolution of comfortable functions, continuous acoustic psychological experiment is carried out. It is then confirmed that the results obtained by the experiment are correlated with the result obtained by the conventional experiment. Through the many experiment for a certain tester, it is confirmed that there is optimal Chirp period to maximize comfortableness. The active control experiment with the optimal Chirp period shows that the optimal Chirp period is effective.

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エンジンの信頼性向上の課題の一つであるピストンスラップによるライナーキャビテーションの発生を設計段階で予測して防止対策を事前に検討できるツールを開発するために,冷却水室壁が振動することによって発生する圧力変動予測法を開発し,その妥当性を実験が容易である空中状態の試験結果と比較して検討した.冷却水室内音場解析モデルについては,音場の共振周波数がシリンダー間の隙間の影響で大幅に低下するモードが存在することが実験結果と解析結果で確かめられた。また最低次の固有振動数として水室内の音場全体が同位相で共振するモード(ヘルムホルツ共鳴器)が存在することが新たに分かった.エンジンブロックの振動応答は固有振動数,応答振幅ともに実験結果と解析結果はほぼ一致することが確認できた.音場の圧力変動応答については,固有振動数の予測精度は10〜20%の誤差があり,まだ改良の余地がある.また,振動によって励起される音圧の応答振幅についても実験結果と比較できる程度の値は得られたが,まだ不十分であり音場形状,減衰特性,境界インピーダンスの評価法などの検討が今後必要である.

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This paper analyzes the torque performances of two kinds of noncontact spinning mechanisms, which are the linear driving type mechanism and the rotational driving type mechanism. In these two noncontact spinning mechanisms, the suspension of the suspended object is realized in the vertical direction by a suspension device using a permanent magnet and a linear actuator, and the spin of the suspended object is realized by the variable flux field around the suspended object. The flux field is changed by the linear movement of permanent magnets in the linear driving type mechanism and by the rotational movement of disk magnets in the rotational type mechanism. In this paper, first, two kinds of mechanisms are introduced. Second, the suspended object is modeling and the experimental device is installed using the strain gauges. Finally, the rotational torque results of the two kinds of mechanisms are shown and discussed.

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In the recent year, we produced some contact-free actuation model by using diamagnetic graphite (PG) plate. We have obtained some experimental results of the diamagnetic force acting on the asymmetrical PG plate by the quasi-static measurement method. And, it revealed that there was clear different diamagnetic force acting on an asymmetrical PG plate sample related to contact-free motion. In this paper, we propose the experimental result of diamagnetic force acting on several edges shaped PG plate samples above the test PM track by the quasi-static measurement method, and would like to consider the extremely contact-free motion of PG plate sample.

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In this paper, linear actuator with electromagnetic force and restoring force of beam is discussed. In this actuator, pull-in problem occurs due to nonlinear electromagnetic force. Open loop oscillatory control had been proposed as a solution for this problem. On the other hand, closed loop control can be applied; so we compare and analyze two control methods. So we consider the time delay and zero order hold. As a result, it is observed that open loop control is better control method than closed loop control under effect of the time delay and zero order hold.

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エネルギー問題が顕著になっている昨今において,エネルギーの有効活用は非常に重要視されており,その一つとして電力貯蔵用フライホイールが挙げられる.そのフライホイールの支持方式としては接触型と非接触型が考えられるが,接触型軸受では摩擦損等により長時間の貯蓄は不可能である.そのため,磁気により浮上を行う非接触型軸受が電力貯蔵用には有効であると考えられる.しかしながら,磁気浮上は不安定なシステムであり,安定化のために吸引力すなわち電流の制御を要する.本研究はエネルギー消費を最小化する為にバイアス電流に制限を与え,必要に応じて印加することで剛性と磁気軸受の線形性を高める手法を提案し,実現した.これにより,以前のバイアス制御とは異なりバイアス電流を定常的に流さずとも突発的外乱に対する安定化が可能であることを示した.

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This paper deals an electric vehicle with flywheel energy storage system using active magnetic bearings (AMBs) and gimbal. At first the equation of motion of a flywheel energy storage system using active magnetic bearings and gimbal. This equation of motion is a strong nonlinear equation. So, the approximated linear equation of motion is derived and the usefulness of this approximated equation is made sure by experiments and simulation. The spring constant of gimbal mechanism influences the natural frequencies. The best design of gimbal should be extreme low natural frequency of gimbal. Finally, the ideal gimbal design method is proposed.

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This paper presents an application of negative stiffness to carrier suspension system. The suspension is located under the center of gravity of the carrier system, which is similar to that in automobiles. In the conventional positive stiffness suspension system, the loading platform tilts to the unstable direction by inertial force during acceleration and turning. deceleration and This problem can be solved by using a suspension with negative stiffness because, the platform tilts to the stable direction, which is similar to the pendulum-type carrier. The negative stiffness is realized by zero-power magnetic suspension with disturbance feed-forward control.

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In this research, it proposes the drive and levitation method by giving to alternating current magnetic flux to magnetic material disc. When the magnetic material disc receives the a.c. magnetic field, we can observe there are a phase difference and an axially attraction force between the impressed magnetic field and the magnetized disc. We executed the levitation drive experiment, and we achieved a steady levitation and the drive by controlling the amplitude of driving a.c.. We developed a new motor that achieved the drive and levitation with a single driving coil system and clarified this fundamental characteristic.

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A 5-DOF self-bearing motor has been proposed to achieve a compact active magnetic bearing (AMB) system. The 5-DOF self-bearing motor possesses the functions of a motor, two radial AMBs, and an axial AMB. Therefore, it is possible to downsize the AMB system with maintaining high performance. In this paper, an outer rotor type 5-DOF self-bearing motor is analyzed to realize the further downsizing for the application of an artificial heart using 3 dimensional finite element method. The analytical condition is set that the motor torque is 0.03Nm, the control force is quintuple of the rotor gravity (5G). The results show that the downsized 5-DOF self-bearing motor is applicable for an artificial heart pump.

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This paper presents a new modeling method and a control system design procedure for a flexible rotor with many elastic modes using active magnetic bearings. To achieve this, it is necessary to control motion and vibration of the flexible rotor simultaneously. The new modeling method named as Extended Reduced Order Physical Model is presented to express its motion and vibration uniformly. By using this model, a PD (Proportional-Derivative) controller to levitate the rotor and a LQ (Linear-Quadratic) controller to suppress its vibration are designed.

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This paper suggests a method to control an unbalance vibration of the magnetic bearing by model bridge control. Model bridge control is the Multi-Freedom control theory that we propose and can compensate for each control problem, e.g. disturbance response. In this paper, a controller design method using a disturbance compensation characteristic of model bridge control is shown. The controller gets possible to control a unbalance forced vibration with the specific frequency by using a disturbance model. The effectiveness of the proposed method is clarified by simulation.

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This paper proposes a simultaneous suspension of two different weight iron balls with a magnetic suspension system using flux path control method. In this system, the suspension force is generated by a disk-type permanent magnet, and controlled by varying the angle of the permanent magnet that is driven by a rotary actuator. In this paper, first, the suspension principle is explained, and the prototype is introduced. Second, the characteristics of this system are examined by some basic experimental results. Third, basing on the examination results, a model is created, and the controllability is proved theoretically. Finally, the simultaneous suspension experiments are carried out. Some results of suspension are shown and discussed.

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Multiple magnetic suspension suspends multiple floators with a single power amplifier. It is classified into parallel magnetic suspension and series magnetic suspension. In this paper, the feasibility of parallel magnetic suspension is studied experimentally. Parallel magnetic suspension systems are classified into according to the output type of amplifier and the connection method of coils. However, the polarity of electromagnet has not been treated yet. This paper focuses on the current-controlled multiple suspension system with different polarities. Stable levitation with two floaters is achieved by using PD control.

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Experimental Statistical Energy Analysis (ESEA) is applied to analyze the vibration energy flow of violin structure. Two kinds of different violins are compared from power transmission. As a result, we found that the violin with better characteristic has three different features compared with the other. Primarily the body structures have low damping. Second the power input to the body structure is in proportion to the frequency reversely. Finally the vibration energy on the upper panel is effectively transferred into the lower panel through the sound-post.

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An automatically performing bell system, which informed the specified time with music, has many types of bell configuration and arrangement. The first requirement for the bell system is to tune the fundamental resonance frequencies of each bell to an equal temperament of scale. Finite Element Method was used to determine the natural frequency of the bell and the effect of bell profile such as thickness and diameter on the natural frequencies was analyzed. The tuning algorithm of the fundamental and higher mode frequencies by changing the inner profile of the bell to improve the sound quality was developed by use of FEM and its availability was confirmed. Moreover, Boundary Element Method was applied to evaluate the sound radiation efficiencies of natural vibration modes of the bell.

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