Sound absorbing poroelastic materials are widely used for noise reduction. One of the evaluation indexes indicating the performance of the sound absorbing material is a sound absorption coefficient. The sound absorption coefficient depends on the microscopic structure of the sound absorption material. At the moment it can calculate a sound absorption coefficient from microscopic structure, but it is difficult to design a sound absorbing material having a target sound absorption coefficient. In this research, we hope to design the microscopic structure of the sound absorbing material having the desired sound absorption coefficient and aid in material design. We express dynamic behavior of the sound absorbing material by Biot ’models, and microscopic structure assume a cubecell or a kelvincell. The flow resistance and characteristic length of a cubecell or a kelvincell are related to the unit cell size by the homogenization method. We use the unit cell size, the modulus of elasticity and the loss factor of the solid phase as design variables and search for a combination of values that minimizes the square residuals with the specified sound absorption coefficient by genetic algorithm (GA).We make microscopic structured model of provided unit cell size by the homogenization method inspected it. As a result, we were able to obtain an almost desired sound absorption coefficient.

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In this paper, a novel education of motion control for various engineers at our company. Curriculums of general seminars are for specialists. Therefore, participants of these seminars are limited. So, a seminar for engineers of our company, who are not specialists, is considered. In the proposed seminar, methods to achieve goals of seminar can be chosen. Seminar contents of motion control are shown, and a device of torsional vibration system is shown.

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Faculty to develop teaching materials is expected for teachers to respond to the needs for technology education which changes in times. However, they had few experiences to learn developing teaching materials in technology education training. In this study, we propose a PBL education program to develop new teaching materials for technology education students using brainstorming with KJ method, mind mapping and PDCA cycle. We have put our program into practice in the metal working class of graduate school, and examine the effectiveness of this program by the qualitative analysis of students’ descriptions.

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Most activity for career formation for job hunting of university students is generally supported by career counseling bureau of university. We professors are continuously instructing students through research activities and lectures. However, it is very difficult to support and communicate their career formation only by research activities of each laboratory. The purpose of our project is to construct new ways of support for career formation based on activity for job hunting with the use of the partnership among our small collaborations, i.e. Kanagawa Univ., Gifu Univ., NPO Okaeri, and Trans Cosmos Ltd. In this paper, not only the support for career formation based on activity for job hunting but also the process of collaboration among our organization with each different output are reported.

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This paper describes the analysis method of the cuboid acoustic field including an acoustic absorption material whose shape is also the cuboid. The acoustic field was analyzed by two methods: one method installed a significantly light and flexible plate into the interfacial boundary, and the other method used an acoustic field whose interfacial face was opened. The characteristic of the acoustic absorption material was represented using complex density and complex bulk modulus. The effectiveness of the proposed method was verified through the comparison of simulation results using the proposed method and exact solution.

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This paper describes new method for selecting optimal field points in Inverse-Numerical Acoustic analysis (INA), and its application to construction of a sound source model for diesel engines. INA identifies the surface vibration of a sound source by using acoustic transfer functions and actual sound pressures measured at field points located near the sound source. When measuring sound pressures with INA, it is necessary to determine the field point arrangement. Increased field points lead to longer test and analysis time. Therefore, guidelines for selecting the field point arrangement are needed to conduct INA efficiently. The authors focused on the standard deviations of distance between sound source elements and field points and proposed a new guideline for optimal field point selection in our past study. In that study, we verified the effectiveness of this guideline using a simple plate model. In the present study, we used a new guideline for optimal selection of the field points and constructed a diesel engine sound source model, which we installed on an agricultural machine. During sound pressure measurement at the field points, the microphone spacing and distance were decided by using the new guideline. Moreover, the number of the field points was changed by analysis frequency. It was confirmed that it is possible to construct an efficient sound source model using the new guidelines. In addition, the surrounding sound pressure level of the engine was predicted using the sound source model, and confirm the accuracy of the model.

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Ball mill is a kind of grinding equipment in the mineral and chemical processing industry. Many balls called media are put into a mill with material, and the mill is rotated. Material is grounded by collision force due to contact between the material and the balls or mill wall. During operation, mills emit vibration and sound. The vibration and sound of mills contain information related to inside of the mill and are useful for operation control. If the relationship between the internal status and the measured vibration and sound signals is clarified, we are able to estimate the internal status of the mill. In this study, we develop a simulation model for analysis of structure-borne sound of the ball mill during the operations. At first, the motion of balls and material to be ground in the mill is simulated by discrete element method. After that, the vibration of the wall of the mill and the radiated sound are estimated. As a result, it is found that both the amplitude of the vibration response and the radiated sound increase in each peak frequency as the rotation speed increases. When the rotation speed increases, the highest point of the balls and material become high. Therefore, the balls and material collide with the wall surface of the mill at high translational speed, and the exciting force to the mill wall becomes large. Moreover, the difference in the amplitude value of the peak frequency clearly occurred at high rotation speed.

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In the design of the cabin such as a car and an agricultural machine, the construction machine, it is necessary to consider about the acoustic feature in the cabin, and to design it. However, I hear that it is possible only to the frequency range of approximately 0-300Hz by the analysis using FEM. On the other hand, the frequency range of 300-1000Hz, called ‘middle frequency range’ is regarded as important about the design of the cabin, but the analytical technique of this range is nonestablishment. Therefore we perform a study to suggest the new analytical technique of this middle frequency range. In this study, we suggest the analytical technique of the acoustic absorption sound field using the mode distortion energy method as the first stage of analyzing a cabin. By this technique, we demand the energy of the air domain and the energy of the sound absorption material domain from the model that sound absorption material was added to on the wall of the cuboid space each and derive the same loss coefficient by the ratio of energy used by energy and sound absorption material of the whole space. At first we compare the truth level by the theory analysis with the solution of the same acoustic absorption sound field by the suggestion technique in simulation and confirm the validity of the suggestion technique. Then, we compare it with the experimental value in the model who stuck sound absorption material on the wall entire surface and the model that stuck sound absorption material on a part of the wall and confirm the validity of the suggestion technique experimentally. Finally we perform a comparison between suggestion technique and classic technique using A and show the thing that is more correct than classic technique.

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There are several types of sound localization methods. In middle frequency around 1kHz, These methods are effective to detect the sound source location. However, for low frequency sound under 100Hz, almost sound localization methods do not have enough resolution to detect the sound source location. To overcome this problem, the author is now developing a new sound localization method, "Double Near-field Acoustic Holography method." This method is converted method of conventional Near-field Acoustic Holography method. The Near-field Acoustic Holography method has best resolution in all sound localization method. However, for low frequency sound sources lower than 100Hz, this method dose not have enough resolution to detect the its position. The proposing Double Near-field Acoustic holography method is developed to improve the resolution of low frequency sound localization. In this paper, the experimental results with small speaker are reported. By these experiments, it is probed that the proposing Double Near-field Acoustic holography method has enough resolution to detect the position of the low frequency sound source.

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This paper describes a study on control of radiation directivity for auditory signals. A model analyzed here consists of a primary point source and one or more passive point sources when the primary source radiates a pure tone with a constant volume velocity. The passive sources respond acoustically to the applied sound pressure radiated from the primary source in same frequency. The relation between the volume velocities of the passive sources without any limitation and directivity is analitically obtained first. The limitation on the amplitudes and phases are taken into consideration next. The effects of the acoustic impedance on the directivity in case of the single passive source are discussed in detail.

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We have studied the sound quality improvement of the classical guitar. The running-in of really playing on the guitar as well as the manufacturing process of guitar gives the large influence to the sound quality. It is called an aging effect. It is important that the behavior of the aging effect is considered on the manufacturing process. Using the aging method of giving the continuous acoustic excitation to a new guitar, the period of the aging is shortened and we were able to confirm the change of the sound quality by the aging effect. Besides, it is clear that the excessive heavy aging gives the aged guitar the less sound expression performance.

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This paper is concerned with estimation of non-stationary excitation forces by the augmented Kalman filter. To reduce vibration and noise, it is important to grasp excitation forces for machines in operation. When excitation forces can not directly acquired, an indirect procedure is necessary to estimate inputs from vibration responses. The indirect estimation procedures are generally classified the estimation in frequency domain and in time domain. Especially, the time domain procedures are suitable to estimate non-stationary excitation forces. In this paper, we deal with the impulse forces of the 5 degree of freedom system as the non-stationary input. The augmented state system is considered with the state vector which consists of displacements velocities and excitation forces. Then the impulse forces are estimated by the augmented Kalman filter with acceleration responses. The estimation experiments for various sampling times are carried out to consider estimation performance.

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The vibration and noise problems of machine in operation occur frequently. Various works related to the transfer path analysis (TPA) have been published to improve these problems. The estimation of excitation forces of mechanical structures is one of important issues in TPA. The excitation forces have been generally estimated in frequency domain. However, many researchers recently attempt to estimate excitation forces in time domain. The purpose of this study is the development of an estimation procedure in time domain for the excitation forces. An advantage of the procedure in time domain is the estimation of transient input signals. Therefore, impulsive forces as an transient excitation signal are estimated. An estimation procedure which employed the singular value decomposition and Tikhonov regularization is proposed in this study. The block Toeplitz matrices are assembled from impulse responses of the theoretical and the experimental systems. The procedure is carry out to solve the ill-posed inverse problem. The validity of the proposed procedure is verified by numerical calculations and experiments for a multi degree of freedom system. Finally, the estimation results of implusive excitation forces are considered from the view point of the number of modes constructed the impulse responses.

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Hydraulic breakers make a loud noise during demolishing concrete structures or rocks, etc. It is considered that one of the major sources of the noise is the longitudinal vibration resonance of a chisel of the breakers. Hence, in order to suppress the noise, a chisel which a dynamic damper is integrated is proposed in this paper. The dynamic damper consists of ring-shaped weight and ring-shaped plastic spacers. To install the dynamic damper, a portion of the chisel must be made slender because the diameter of the chisel is limited considering attaching to the breakers. The resonance frequencies of longitudinal vibration modes of the chisel are changed with parameters of the dynamic damper, such as size and position, etc. Therefore, it is difficult to design the dynamic damper with conventional ways. First, response of the proposed chisel vibration is derived with the transfer matrix method theoretically. Second, experimental results of the frequency response are shown and confirm the validity of the theoretical model. Then, effects of the parameters of the dynamic damper are investigated with the model. Finally, the experimental results are shown, which sound noises were measured when the chisels were impacted with a breaker. These results show that the proposed chisel is valid and feasible for reducing the noise from Hydraulic breakers.

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Dynamic vibration absorbers are widely used mechanisms for vibration suppression, and their design methods are diverse. For forced vibration, there are the fixed point theory which is often used and the minimum variance criterion which is based on H2 theory for random vibration. For transient vibration, there is a stability criterion and others. However, these are design methods when the mass ratio is fixed, and as far as the authors know, there is no dynamic vibration absorber design method to deal with the change of mass ratio. In this paper, we summarize the design method of the dynamic vibration absorber considering the phase margin and its calculation result, and show that we can cope with the change of mass ratio.

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Bronchial asthma and Chronic Obstructive Pulmonary Disease (COPD) are respiratory illnesses that cause a change in specific acoustic impedance from vocal cords to the lungs. The purpose of our study is to measure the specific acoustic impedance at the vocal cord. A transfer matrix to express a vocal tract shape is necessary to find the specific acoustic impedance at the vocal cord. A past study has provided the vocal tract shape of a normal person. However, we need to find the vocal tract shape of each subject. In addition to partial and total derivatives (differentials) in the numerical value experiment, we can arrive at an accurate value of the specific acoustic impedance of actual part at the vocal cord by using the Moore _ Penrose inverse matrix. I made an acrylic model that simply reproduced human body. In model experiments, qualitative trends appeared, but quantitative differences could not read. I’m going to make measurements with people many times with trial and error.

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In recent years various diseases exist in the world. In this study, we target at Pulmonary Hypertension that is known as the intractable disease. The treatment at appropriate timing is particularly essential to the 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 affected by the conditions except the blood vessel. For this reason, this diagnosis method don’t reflect the disease state exactly. Therefore we perform a study 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. We confirmed that a phase angle fluctuated depending on the severity of a patient's illness by comparison among simulation results, experiment results, and clinical results. In addition, we showed the effectiveness of the diagnosis method that we proposed. We considered the cause that a phase angle was greatly over.

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This paper describes a product quality check of small fan motor vibration by using rotational swing mechanism. The small fan motors are used by many electronics equipment for cooling. They are essential for present industry. But, small fan motors have been checked by inspectors who have special skills which are based upon their auditory organs and tactual senses. It is not easy that inspectors will have mastered those skills. In addition, those skills sometimes depend upon their mental and physical condition. Now, new evaluation and diagnosis method is needed. This study focused on the motion of inspector’s handwork to develop a new diagnosis method of small fan motors. In the experiments, the acceleration of small fan motor’s vibration has been measured, and the difference between maximum and minimum of the acceleration RMS level and time average value has been taken as the index to show the vibration amplitude. These results show the proposed method can be a new evaluation method for the diagnosis of small fan motor’s vibration.

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In this paper, we propose an identification flow of contributing factors to the difference of FRFs between a finite element model and an actual structure. Conventionally, to identify the factor of difference, a driving point FRF of the part in the assembled structure is compared in a FE-Model and an actual structure. But it is difficult to identify whether the part is factors of difference with accuracy, because the other parts also influence the driving point FRF. As the other conventional identification flow, there is a model-update method that update the model minimizing the difference of FRF by using the structural sensitivity. However, the model update-method cannot also identify the factor with accuracy. Because the model-update method just optimize a FE-Model. Therefore, we propose a boundary node constraint method which compares driving point FRFs between a FE-Model and an actual structure. By the constraint, driving point FRFs are independent of other parts, and accordingly those vibration characteristics have no influence of other parts. Using the nodal constraint method, it is possible to identify factors to the difference of FRFs in the joint part by selecting the constraint point. And it is possible to identify that factors of the difference of FRFs exist in mass or stiffness by comparing mass line or stiffness line of the FRFs. In this paper, the nodal constraint method is verified numerically by FE-Models simulating experimental FRFs.

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In structural design, natural vibration must be appropriately considered. One of the most commonly used prediction methods for natural vibration is finite element analysis frameworks. However, the FEA frameworks cannot clarify the natural vibration formation process because the natural vibration is directly computed using mass and stiffness matrices. On the other hand, the wave analysis frameworks can visualize the eigenmode formation process. Therefore, this paper computes the natural vibration formations of three-dimensional beam structures considering joint stiffness. The natural vibration formation is discussed using computed waves. The waves indicate that the natural vibration can be designed by the joint stiffness based on local transmission and reflection properties.

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For the purpose of designing FRF baselines, we propose a method to simplify a design formula of the amount of wave propagation. In this method, focusing on the interference of the wave, we approximate the amount of wave propagation by tactically ignoring the effect of near field waves. By using this formula, it is possible to design the target frequency ranges to minimize the wave propagation amount. In addition, this formula can be utilized as a design tool of the baseline of frequency response functions, which obeys wave interference on the waveguide. As a case study, it is shown that the wave propagation path can be changed by adding damping elements on a lattice structure. It is also shown that desired design of the baseline of frequency response functions is available by the change of wave propagation path.

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The identification of external force acting on a machine or a structure is important for diagnosis. One of the force identification methods is based on the frequency response function (FRF). The method is very useful although it requires the information of the location of acting force. In this study, an identification method is proposed for the case of unknown excitation points. In the method, the inverse problem of force identification is regularized by increase the number of FRF by adding a mass on the target structure. The validity of the method was checked by the numerical example and the experiment for a beam structure elasticity supported at both ends. To solve inverse program, two regularization filters, which are the truncated singular value decomposition (TSVD) filter and Tikhonov filter, are used in the numerical example. It was shown that the accurate identification results can be obtained by TSVD filter. But in the experiment, the accurate results cannot be obtained by using TSVD filter.

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This paper proposes identification method of excitation force of rigid body vibration source by constructing modal model without force signal during preliminary excitation test. If the reworking occurs after the assembly of the prototype in mechanical product, the cost increases due to the retrofit countermeasures and development period extension. Pre-prediction of vibration at the design stage is important to avoid these problems. Prior prediction of vibration needs to grasp the excitation force of the vibration source. As conventional methods, the mount stiffness method and the matrix inversion method have been proposed. However, mount stiffness method calculates the mount transmission force. Therefore, if the development machine changes the structure, preliminary evaluation does not apply. The matrix inversion method can solve this problem. However, when the frequency response function contains a measurement error, the error spreading propagates in inverse matrix calculation. Therefore , in order to avoid the inverse matrix calculation, until now authors have proposed method for identifying excitation force by building a physical model. However, with this method, it was necessary to use the force signal at the preliminary excitation test for identifying the modal parameters for constructing the modal model. For this reason, it is necessary to perform vibration with a vibrator equipped with force measuring device. When the real structure is targeted, there is problem that it is impossible to secure the excitation points due to interference with surrounding equipment. In order to solve this problem we propose identification method of excitation force of rigid body vibration source by constructing modal model without force signal during preliminary excitation test. In this paper, the validity of the method was verified by basic experiment. As a result of study, proposed method shows that a modal model can be constructed without using the force signal at the preliminary excitation test and that the excitation force can be identified accurately.

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In a typical mechanical product, it is a general method that identify the deformation mode in which significant improvement target of contributing to the response from the experiments and analysis solution and consider the improvement structure in the way of high rigidity by using a technique such as strain energy method in the conventional design and development. However in the above-mentioned method, it is often a conflicting results with weight saving and cost reduction of development requirements. Transfer path analysis (TPA) using the Finite Element Method (FEM) is an effective method of reducing noise and vibration of the automobile with respect to these issues. TPA can reveal that the transfer path from the input to the response of the evaluation point and the contribution of the path and consider the response improvement efficiently. TPA using FEM was applied to mechanical structure with a variety of transfer paths and evaluated the contribution of the vibration transfer path for the vibration response reduction. The previous research have reported that it is effective to reduce the vibration response of the evaluation point by modifying the structure of the path in the case of a path has the dominant contribution. However, there are problems that the structural change guideline for the contribution analysis result is unclear and it is not possible to propose the modification guideline for the mechanical structure when the contributions of multiple paths are dispersed. In order to solve these problems, it is proposed to evaluate contribution in each degree of freedom by utilizing characteristics of the TPA. Then, it is verified that whether the vibration response of the evaluation point can be reduced by controlling the contribution by suppressing the transfer force with large degree of freedom of contribution. As a result, reduction of the vibration response at the evaluation point was realized by controlling the contribution to the frequency at which the contributions of multi paths were dispersed, which was the conventional problem by the proposed method.

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This paper describes new vibration analysis methods for continuous bodies using the modal analysis. The substructure synthesis method is often used to consider the coupled vibration. The substructure synthesis method adds substructures. In contrast, the proposed methods subtract substructures from one structure, or change the characteristics of several parts of one structure. Because the proposed methods use only the vibration modes of the original one structure, number of the vibration modes does not increase unless the shape of the continuous body is simple. Based on this new concept, the governing equations of the several examples of the analytical models were derived, and the effectiveness of the proposed method was verified through simulations.

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This paper proposes a method of Lamb wave generation based on laser ablation with damage prevention chip for non-contact damage detection for huge objects such as aircraft structures. In recent years, a damage detection method using Lamb waves has been studied. In many cases, contact devices such as a piezoelectric transducer and an ultrasonic probe are used to generate Lamb waves. However, these methods take a lot of measurement time to inspect damage. Although Lamb waves generation using laser ultrasonic as non-contact method has been studied to improve the disadvantage, generated Lamb waves are measured with low signal-to-noise ratio. Therefore, laser ultrasonic is difficult to be applied to detect damage in wide area. We have realized a Lamb wave generation using a laser ablation excitation force. On the other hand, laser ablation causes submillimeter damage on target structures. In this paper, we propose a method of Lamb wave generation with damage prevention chip on the duralumin plate. Lamb waves were generated by Nd: YAG pulse laser and detected by scanning laser Doppler vibrometer. We evaluated the characteristics of broadband Lamb wave generation by laser ablation with damage prevention chip.

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This study concerns measurement of natural vibration of three-dimensional acoustic space by multi-point excitation using decentralized control. A set of acoustic excitation system consists of a speaker, a microphone, and a local feedback controller. The acoustic excitation system targets the frequency range from 100Hz to 500Hz that often becomes a problem at automobile interior noise. Natural vibration of three-dimensional acoustic space crowds in the narrowband. One-point excitation is a useful technique that can be used to measure natural vibration easily but not suitable for excitation of natural vibration that crowds in the narrowband. Multi -point excitation using centralized control is general technique and it requires different adjustment of each speaker according to modes. Therefore, its control becomes complicated when number of excitation-point is increased and this is the current problem of multi -point excitation technique. In this paper, as a technique that can measure natural vibration of three-dimensional acoustic space easily, proposes multi-point excitation using decentralized control by local feedback control that makes acoustic space into condition of undamped vibration. Natural vibration of three-dimensional acoustic space is measured using the four acoustic excitation systems that is local feedback controlled and input the excitation signal into only one of the four acoustic excitation systems. To reduce effect of acoustic damping by local feedback control, the frequency peak of transfer function is sharpened and some modes that are not able to excited by one-point excitation is definitely excited.

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Design space of vehicle acoustic performance is restricted by strong demand for weight reduction of a car body. This paper focuses our effort on the improvement of vehicle interior acoustic performance with the least increase in weight, by adding periodic structures to the panels. It is generally known that a sound pressure level at an evaluation point is dominated by the correlation between structural panel mode shapes and acoustic cavity mode shapes. As structural vibration modes are a superimposition of waves, the functional mode shapes, which has a function to reduce interior noise, may be designed by passive wave control using periodic structures. In this paper, a part of a panel is structurally modified with periodic structures to obtain functional mode shapes. By the periodic structures, the waves in a specific frequency band cannot propagate in the modified part of the panel. This enables us to design intended functional modes by virtually changing panel configuration to the simple panel, such as a rectangular panel, by filling up a part of the panel by the periodic structures. The advantage of this method is that the eigenpair of rectangular panels is readily designed by hand calculation.

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Computer-aided engineering is widely used in mechanical engineering to analyze the noise and vibration performances of components and assemblies. Recently, a more detailed finite element model (FE model) with a large number of degrees-of-freedom has been in use, owing to developments in computer technology. This FE model is better suited to examining the effects of changing physical parameters such as the material stiffness and structural, details. On the other hand, with the FE model it is difficult to develop effective countermeasures for reducing noise and vibration because of the increasing number of modes in unit intervals of frequency. For such a problem in the frequency range of high mode density, earlier studies presented different mode classification methods. Representative modes among mode groups are useful for developing countermeasures. However, studies have not presented a method for extracting representative modes by which the frequency response function (FRF) can be recalculated. In this paper, a new method of extracting representative modes is proposed in order to recalculate the FRF with a smaller number of modes. First, a mode grouping method is employed with a beam and spring-mass model. Second, a new FRF in a mode coordinate system is derived by summation of the FRFs of the same mode group. Representative modes are derived by the FRF in a physical coordinate system and a new FRF in a modal coordinate system. Finally, we present an approach to reduce the vibration for an evaluation point using the representative mode.

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In a vehicle body design which focuses on noise and vibration, it is necessary to achieve two contrary requirements, mass reduction and improvement of noise and vibration performance. For those requirements, experimental measurement and finite element analysis are applied. However, there are advantage and disadvantage in an experiment and a finite element analysis each. In the experimental measurement, it is possible to obtain the actual vibration, but the measurement of detail stress-strain distribution is difficult. The stress-strain distribution is necessity to find the contributing part to noise and vibration. On the other side, in the finite element analysis, it is possible to compute a detail stress distribution, but the prediction accuracy is low for structures with many joints like automotive body. In this paper, analytical method that hybrid the advantage of experiment measurement and finite element analysis is applied to dynamic problems. Morton et al. applied hybrid analysis method using measured displacement by Moiré interferometry or laser speckle interferometry as the boundary condition to the finite element analysis. In this report, we apply the hybrid finite element analysis to dynamic problems and verify the prediction accuracy. The vibration velocity of the region of interest was predicted by measuring the vibration velocity of the interface and giving the measured vibration velocity as the boundary condition of the finite element analysis. The vibration response of the region of interest can be predicted in the low frequency region. In the hybrid finite element analysis method, there is an advantage that it is not necessary to calculate the inverse matrix of the transfer function in the process of obtaining the vibration velocity of the region of interest.

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Various parts and equipment are attached to the bogie of the railway vehicle. These parts are subjected large vibration during running. The accident rarely happens that the parts are fall by this vibration. Therefore, the vibration prediction technique of the bogie is needed. The authors have proposed a method of predicting the vibration at the evaluation points in the bogie from the impact test carried out with the vehicle stationary. It was confirmed that the proposed method could predict the vibration during the running on the commercial line up to 100km/h. In the previous research, only one vehicle was examined. In this paper, the results of applying to the other two vehicles were shown. As the result, the proposed method could be applied to two vehicles. However, it was shown that the best condition of the impact test was different according to the type of vehicle or the evaluation point. Therefore, the running test results in the depot were used as a new excitation method. The accuracies of the prediction were improved by using the results of running test in the depot. However, it was needed that the multiple coherences between the vertical acceleration of the axle boxes and evaluation point were sufficiently large.

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It is one of the important issues to investigate the vibration environment of railway bogies, since the vibration of the bogies may result in loosening bolts which fix the parts to the bogie frames or/and fatigue fracture of the parts themselves. A simple technique for predicting the vibration of bogie parts has been proposed in which the acceleration power spectral densities (PSDs) at evaluated points are predicted with the identified frequency response functions (FRFs) between the axle boxes and the evaluated points, together with the measured accelerations of axle boxes. Stationary excitation tests were conducted in the previous studies to identify the FRFs, and the axle boxes or rails were hit with impulse hammers to excite the bogies, while the new approach without the stationary tests is proposed in this study. The FRFs are identified with the accelerations acquired in the preliminary running tests in car depots. The proposed technique are applied to the vibration prediction of the bogies for two types of railway vehicles: an electric car and a diesel car, and the differences or ratio between the predicted and actually measured PSDs are evaluated. It is confirmed that the prediction accuracy can be improved in the case where not only the vertical but lateral and longitudinal accelerations of axle boxes are considered as the excitation inputs.

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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. The perforated plates are generally used with a cavity to obtain the suppression effect effectively. However the perforated plates change the acoustic natural frequency of the sound field of the duct. In previous paper, this was not referred. This paper aims to clarify the role of the perforated plates when it changes the acoustic natural frequency of the duct. In this study, one dimensional duct will be used for simplicity and the relationship between the aperture ratio and the acoustic natural frequency will be obtained analytically and experimentally. As a result, it was clarified that the analytical results are in good agreement with the experimental ones and the plates with holes had a role of acoustic damping in calculation of the acoustic natural frequency of the one dimensional sound field like a duct with plates with holes.

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In the development of automobile engines aimed at low pollution and high mileage, the monitoring of the combustion state of each cylinder is important. With combustion monitors, the pressure diagram is measured each degree of the crank angle (360 pulses/rev.), and parameters such as the indicated mean effective pressure, which directly indicates the work in each cycle, are broadly calculated. Although pressure diagram measurement is mainly performed in engine bench tests, recently, testing on actual vehicles or in a state close to an actual vehicle is increasingly being performed. On-Board tests differ from bench tests in that it is difficult to attach a crank angle sensor, and the crank angle signal of the computer for engine control (ECU) is considered to be taken as the sampling pulse. However, the interval of the ECU’s crank angle signal is wide at 6 degrees (60 pulses/rev.), and so a missing tooth is provided to detect the TDC position. This missing tooth is considered to be the cause of error in IMEP calculation. In this paper, we calculated IMEP from the pressure diagram that was generated at a sampling interval equivalent to the crank angle signal of the ECU, and investigated the calculation error on IMEP obtained from the pressure diagram that was measured at every degree. As a result of this, the calculation error changed due to the untoothed crank angle, and error increased the most when the missing tooth was in the vicinity of 30 degrees from TDC. Accordingly, it was found that an error-reducing measure was possible by setting the untoothed crank angle to an appropriate value. Upon performing verification while taking the pressure diagram mean value at the crank pulse before and after the untoothed crank angle as the pressure diagram of the untoothed crank angle as the countermeasure for this, we confirmed that the calculation error almost completely disappeared, independent of the missing tooth position.

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Accelerometer using zero-compliance mechanism is purposed in this paper. This accelerometer is invented to measure long-period and small oscillations such as ground motions and building vibrations with a high resolution. The zero-compliance mechanism is composed of two suspensions with positive stiffness and negative stiffness. Force acting on the inertial mass at the point of force is proportional to the displacement of the connection point of two suspensions, which is referred to as detection point. Acceleration is estimated by dividing the force by the inertial mass. An experimental apparatus according to the principle is fabricated to study basic characteristics of the proposed accelerometer. To achieve the zero-compliance property, a linear actuator is incorporated into the mechanism. The experimental static acceleration is given to the apparatus by gravity. The static acceleration measurements show that the displacement of the detection point is proportional to the acceleration. It is confirmed that the displacement of the point of force is virtually zero. The dynamic measurement results show that the experimental apparatus and a conventional servo-type accelerometer have mostly same output. These results demonstrate that zero-compliance mechanism can be applied to acceleration measurement.

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Recently, traffic congestions caused by increase in the number of vehicle possession and complicatedness of traffic system have been serious social problems. In order to solve these problems, a lot of attempts have been carried out from various aspects including employing new type of traffic signals with fuzzy control system or neural network system. Several types of simulation systems have been considered as an effective technique to determine how to reduce the traffic load. However, the current simulation system has several problems, which cannot model after on real traffic system. To obtain more reliable simulation results, we need a simulation model that is able to control more accurately frequency of car appearing, type of car, speed, etc. In this study, a traffic flow measurement system has been developed to extract traffic flow data by analyzing images near the intersection from the fixed point camera. The measurement system has been developed by program language C++ and OpenCV library and performance of the measurement system was measured based on recognition rate of the number of cars passing the intersection, the type of cars and driving means speed of passing between two intersections. The average moving speed and whether route change is happening between intersections are measured and presumed by identifying the same vehicle from image data of two locations. It could be confirmed that this traffic measurement system might be available to traffic census and also input data into the simulation system through this study.

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The swarm intelligence has been applied to a mechanical vibration monitoring system for the perfect autonomous computer monitoring system including sensors, actuators and adaptive controllers. The expression of "swarm intelligence" was first used in 1988 in the context of cellular robotic systems, where lots of simple agents may generate self-organized patterns through mutual interactions. As an example, a swarm of ants can find an optimal route between their nest and the food in various environment using special pheromone. In this sense, the network of agents in a swarm may have some kind of intelligence or higher function appeared in a simple agent, which is defined as the swarm intelligence. The concept of swarm intelligence may be applied in diverse engineering fields such as flexible pattern recognition, adaptive control system, or intelligent monitoring system, because some kind of intelligence may emerge on the network without any special control system. In this study, a number of units composed of a sensor and an actuator were distributed on a mechanical dynamic system, and each unit was connected to each other to exchange the information of state variables sensed by each unit. The network of units configured as a mutual connected neural network. A lumped mass system with five degree-of-freedom was prepared as the mechanical system in this simulation, and each unit was placed on each lumped mass. The displacement was measured by the sensor in each unit, and a variable damper was assumed as actuator in each unit. After the several expected vibration-controlled patterns of lumped system were memorized by pattern recognition procedure in mutual connected neural network, then the excited vibration mode was inhibited to the memorized patterns automatically. The result showed that the excited vibration was reduced autonomously by the swarm intelligence configured on the network of units distributed on a mechanical system.

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This paper describes the energy harvesting method using the piezoelectric sound absorbing panel. The piezoelectric sound absorbing panel absorbs the acoustic energy incident on it. Recently, many types of energy harvesting techniques have been studied. These methods extract vibration energy as electrical energy through electromechanical transducers. In this research, the piezoelectric sound absorbing panel was used as the electromechanical transducer. In the piezoelectric sound absorbing panel, the absorbed energy was dissipated through a resistor of the LR circuit connected to the piezoelectric element; however, in this research, this dissipated energy was harvested. The optimum values of the LR circuit that maximizes the amount of the harvested energy were derived, and the effectiveness was verified through simulations and experiments.

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We report miniaturization of the piezoelectric vibration energy harvester using the mechanically-switching SSHI (Synchronized Switch Harvesting on Inductor) circuit, and investigated the performance both numerically and experimentally. We achieved in miniaturization of the mechanical switch structure by employing a cantilever having a pressed semicircular part at the tip. The numerical simulation showed that, interestingly, the output power of the proposed harvester increases as the applied vibration level enhances, while the displacement is held constant. The experimental results exhibited the same results as the numerical investigation. The reason for the increase in output power under the constant displacement is that the vibrational force of the harvester exceeds the vibrational suppression force from the piezoelectric material as the base excitation level enhances, leading to the increased number of switching On/Off and thus the output power.

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In this paper, a broadband vibration energy harvester having a nonlinear oscillator using leaf springs and stoppers is proposed. In the conventional vibration energy harvester having a linear oscillator, there is a trade-off relationship between the magnitude of the resonance peak and the resonance band. Therefore, when the oscillator has a high resonance peak design to increase the power generation efficiency, there arises a problem that power generation efficiency is remarkably deteriorated due to a frequency change of the vibration source. It is well known that when using a nonlinear oscillator, the resonance band can be expanded. However, since the nonlinear oscillator has high and low-energy stable solutions in the resonance band, a mechanism to keep the oscillator responding in the high-energy solution is required to maintain the power generation performance. In the previous study, a response stabilization control to globally stabilize the high-energy solution was proposed. In this paper, a broadband nonlinear vibration energy harvester using leaf springs and stoppers is designed and manufactured. It is shown that the proposed vibration energy harvester with the response stabilization control can successfully operate in a bandwidth broader than 60% of the linear natural frequency.

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Various vibration control techniques using piezoelectric actuators have been studied widely as a major research area of smart structures. This paper focuses on a well-known semi-active technique using inductors, diodes, and switches with piezoelectric actuators. Semi-active control systems using this technique are nonlinear systems with discontinuity and performance evaluation of these systems is not easy because of the strong nonlinearity. A possible approach is using periodic solutions for harmonic disturbance. Previous studies show the periodic solutions by using harmonic balance method. The solutions are obtained in analytical closed form and convenient for understanding of relation between the performance and the parameters of the systems. However, the effects of the higher harmonics ignored in harmonic balance method are not considered enough in the previous studies and the accuracy of the obtained solutions is not clear. This paper shows high accurate solutions obtained by shooting method which is a numerical method for periodic analysis of nonlinear systems. The comparison of the solutions by harmonic balance method and the high accurate solutions shows that the accuracy of the previous solutions is enough for only weak coupling cases.

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This study concerns the design of non-contact handling devices based on near-field acoustic levitation. In the near-field acoustic levitation, a holding force acts on the levitated object, and the lateral position of the levitated object is stably maintained. This holding force is caused by the acoustic viscous stress which can be calculated from the sound pressure distribution. In this paper, a calculation model using the boundary element method (BEM) is proposed to obtain the sound pressure distribution near the levitated plate, and the relationship of the lateral displacement and holding force is computed by using the proposed model. Then, the validity of the calculation model is evaluated by comparing the numerical results with the experimental results in the literature. As a result, it is shown that the proposed calculation method can be used for the analysis of the near-field acoustic levitation, particularly the evaluation of the holding force acting on the levitated objects.

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In piezoelectric shunt damping, which is one of sensorless damping techniques, various problems arise due to the parasitic resistance of the piezoelectric element when using a negative-C R shunt circuit. In this paper, we consider the robustness of the shunt damping system against variations in the parasitic resistance.

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Due to the increase in the size of the space structure, the vibration of the beam is easily excited. Passive damping is preferred in space-limited space. A passive damping system using giant magnetostrictive material is an element that enables passive damping. The giant magnetostrictive material has the property of changing the magnetic flux density around the material when a force is applied. At this time, by winding a coil around the material, current flows by electromagnetic induction. Furthermore, it is possible to consume energy by connecting a resistor or the like to the circuit. This series of flows enabled passive damping, which has been demonstrated in previous studies. In this paper, we propose efficient use of passive damping system using giant magnetostrictive material. When a passive damping system using a giant magnetostrictive material is attached to the vibration damping target, it was found that fixed point appears in the graph of vibration magnification. Optimum tuning and optimum attenuation are performed using this fixed point. As a result, it was found that there were optimum usage conditions, and the behavior and concrete effect of the system when using this system are shown in the graph.

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The present paper deals with the multi-modal vibration control of CFRP laminated plates based on the independent modal space control. A modal sensor for identifying specific vibration modes is constructed by one accelerometer and band-pass filters, where the sensor is optimally placed based on the minimization criterion of observation spillover due to unmeasured vibration modes. Besides, one macro-fiber composite (MFC) actuator is also optimally placed to maximize the induced modal control forces for controlled vibration modes. The proposed optimal placement method of a sensor/actuator using satisficing trade-off method is examined through the numerical examples from the viewpoint of numerical optimization method.

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Flaw detection technology by tapping sound has been established as a powerful method to diagnose structures such as bridges, buildings, tunnels, towers etc. If those structures have defects, the stiffness of the structure decreases, the natural frequencies are also changed and the influence by those changes should appear in tapping sound. Using these features, the purpose of this study is to investigate the possibility of defect diagnosis and estimation of defect position using a cantilever system as the simplest structure. First, the FEM model is made by Salome-Meca. Second, the natural frequencies and the natural vibration modes for the cantilevers without and with defects which are located at every 20 mm, are calculated. And then changes on the natural frequencies and the mode shapes are investigated and examined in order to estimate the defect position. The results show that it is possible to estimate the defect position for the defect positions 250 mm and 405 mm of the cantilever even though the estimated values have some errors of a few percent. It has become clear that the estimation of defect position by analysis of tapping sound obtained from the experimental results can be sufficiently available in this study, if several problems are complemented.

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There are a lot of street lights in Japan. Some of these street light are damaged or corroded by water or condensation in the winter. In the worst case, a street light falls down to injure person or damage a car and so on. To prevent these accidents, periodical inspection is required. Most common inspection methods are visual inspection or thickness inspection by ultrasonic sensor. Visual inspection has following problems, i.e., (1)quality of inspection depends on a inspector, (2)it takes a lot of cost and time to inspect a street light. The thickness inspection by ultrasonic sensor has problems of poor contact of sensor to a street light especially at uneven surface caused by corrosion. In this paper, we excited a street light to measure its vibration and then estimated reduction of thickness of pole for several street lights in Osaka prefecture and checked its performance. Finally, good ability of damage detection was confirmed.

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Hammering test using the inspection hammer is most commonly used to evaluate the defects of concrete structures because it is relatively simple. This method depends on the subjective sense of inspectors to detect defective parts. In this study, we adopt a hammering method using the rotary hammering device to improve inspection efficiency. We move the rotary hammering device along the concrete surface and measure the impact sound near the surface with the microphone attached to the device. The sound characteristics measured from healthy parts and defective parts (four types of defective depth) are compared in the time and frequency domain. The time waveforms indicate the sound pressures for the defective parts are apparently higher than those for the healthy parts when the pressing force applied to the rotary hammering device is appropriate. The frequency spectra indicate the peak frequency of the sound pressure increases and its amplitude decreases with the defective depth.

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In this paper, a simplified screening method for a pole structure such as electric pole, light pole, signal pole, etc., using a modal-based evaluation of the structural local flexibility is proposed. A ratio of the rotational local flexibility of the healthy part to that of the potentially damaged root part is adopted as a damage index, and its approximate calculation scheme is proposed. Using the proposed method, one may quantitatively evaluate the extent of the damages in the root part of the pole by conducting a vibration test identifying the first few modes. By calculating the modal parameters in two directions perpendicular to the longitudinal axis, it is possible to identify the change of the cross-sectional principal axis due to the damage as well as the imparted additional flexibility with respect to the principal axis. Finally, the influence of the identification error of the modal parameters to the damage evaluation is numerically investigated.

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The necessity for the development of micro power supply technologies for mobile phones and portable electronics has increased in recent years. Methods of self power generation using the vibration loads of structures have attracted attention as the power supply technologies. In this study, we focused on lead zirconate titanate （Pb（Zr,Ti）O3, PZT） as the generating piezoelectric element. The purpose of the study isto develop a high-efficiency PZT generator element that utilizes the vibration loads in the support members of a structure. However, piezoelectric elements only generate power in the order of several microwatts, so improving their power generation capacity is of the utmost importance. In this paper, experiments of driving the accelerometer module using the laminated PZT elements under vibration loads of air compressor are reported. Acceleration monitoring system was composed of capacitor, switching circuit, voltage sensor and accelerometer module. The charges generated from the laminated PZT element are charged by the capacitor. And it reaches to the accelerometer module through the switching circuit. To show the laminated PZT element as an effective electric power source, this experiment has driven the accelerometer module with two batteries. As a result, it is possible to obtain the acceleration information, and the laminated PZT generated an electric power for driving the acceleration module by using the vibration of the air compressor. And by driving the battery, it was shown that the laminated of PZT element is effort of a electric power supply method. In this experiment, Receivable distance of the data has been evaluated. Based on these results, the laminated PZT can be applied to monitoring sensor and other applications.

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