The purpose of this work is to show the mapping of a nonlinear dumping vibration system subjected to a random input. In a general, a statistical technique of a higher order spectra(HOS) could be used for non-gaussian data analysis. Here, numerical simulation for an asymmetrical nonlinear dumping vibration system.

抄録全体を表示

Recently, the significance of smooth communication between human and computer in various fields has been increased. The several methods of human speech analysis such as cepstrum analysis, Linear Predictive Analysis etc., have been suggested and evolved up to now. They are mainly related with the analysis-synthesis coding of speech signals in order to realize the characteristic parameters extraction of high quality in the low bit rate coding. On the other hand, the specification of speaker and the perception of emotion also come to be significant in IT technologies. However, there are many unsolved problems in the speech recognition methods, which are related specification of the speaker and to recognize their emotion. Hence, this study introduces the Wavelet Analysis which is taken notice of as an unsteady state signal processing method of Time-Frequency analysis. The purpose of this study is to combine Wavelet Analysis into the traditional speech processing methods, to suggest a new recognition method for the specification of speaker and the perception of emotion which may supply a lot of applications for IT technologies, and to find how to extract the characteristic parameters for the speakers and their emotion. This study reveals that F1 and F2 are the main parameters to comprise the meaning part in the 5 Japanese vowels and F3 is the significant component to comprise the speaker characteristics. It also shows that the formant structure of the five vowels is not influenced by the emotion component included in the human voice.

抄録全体を表示

The purpose of this paper is to clarify the relation between the acoustic characteristics and voice articulation of piezoelectric speaker, which applied to the portable terminal in the car. A piezoelectric speaker is small and thin. In addition, it is suitable for sound reproducing because of the acoustic characteristics in middle and high frequency ranges are effective. In the experiment, the evaluations of voice articulation under car interior noise environment were carried out in order to examine the effectiveness of voice recognition. The experimental results show that the piezoelectric speaker is effective for voice recognition under the car interior noise. In addition to rising of the voice waveform, formant has the characteristic which is emphasized.

抄録全体を表示

The purpose of this study is to design a small sized bone conduction speaker by using piezoelectric vibrator. In the paper, two types of bone conduction speaker are investigated, one of which is the center support type and another is the edge support type. In the experiment, the measurements of frequency characteristic and the evaluations of voice articulation under masking-noise are carried out to compare the center support type with the edge support type. The experimental results show that the center support type is superior to the edge support type in both the vibration characteristics and the voice articulation.

抄録全体を表示

A present manufacturing needs high-value-added. It is especially important that it appeals to sensibility. The change in Modal Stiffness Ratio and Loss Factor when wood is varnished is examined. And the sound pressure level of a classic guitar was measured, and the attenuation characteristic was examined.

抄録全体を表示

This paper develops the numerical model of a curtain-cable in the case of considering both bending stiffness and axial stiffness, friction force between rail and carrier by using finite segment formulation and deals with numerical simulations of dynamic behavior of the curtain-cable subjected to impact loads. The curtain-cable is stretched by an external step load, and internal force generated at the girder end is examined. As a result, it is found that the internal force generated at the girder end increases with increasing the axial stiffness and decreases with increasing coefficient of friction between rail and carrier.

抄録全体を表示

In this paper, the modeling and the formulation is proposed to analyze three dimensions behavior of the elastic rolling disc precisely, and is inspected its validity. The proposed model in this paper consists of a rigid body and some particles of mass that have voigt elements for the local part deformation. This model can grasp both the shape of the elastic rolling disc and the local part deformation in the contact area.

抄録全体を表示

Four legs animals automatically choose the most efficient gait pattern according to the walking speed. This paper describes the mechanism of this automatic selection of gait, from the view point of the natural vibration mode. Then rigid body link model was made and analyzed, by simplifying quadruped walk. The results have shown that the mode shapes of this model are the same gait as animals walk.

抄録全体を表示

As moving bodies on a complicated 3 dimensional trajectory, we take roller coaster as a model. Equations of its motion and conditions of constraints are set up for using the differential algebraic equation (DAE). Then, we propose the simulation method for the motion and vibration of multivehicles. In this paper, in addition to the previous report about the analysis of the constraint on s-z plane (s-axis is the direction of a length of trajectory which is tangential line for the projected trajectory on coordinate x-y), we analyze the constraint on s-u plane (u-axis is perpendicular to s-z plane).

抄録全体を表示

The paper proposes a new modeling method and active suspension control approach for elastic vehicles. While the vehicle designed lightly to get energy saving, it becomes flexible in nature. For obtaining the riding comfort and operation stability of elastic vehicles, there is a necessity to control vibration and motion. In this research, the modeling method calls as 'Extended Reduced Order Physical Model' is used to express vibration and motion of elastic body. A riding comfort and operation stability are improved using active suspension control designed by H∞ and sub-optimal control theories. Effectiveness of the control is demonstrated by simulation and experiment.

抄録全体を表示

This paper discusses the motion optimization problem of multibody systems and an optimal control algorithm for open-link mechanisms is proposed. The algorithm is based on the efficient dynamics computatio algorithm and the optimal control algorithm called hierarchial gradient method developed by authors. An optimal control problem of a 7-DOF manipulator is solved to demonstrate the effectiveness of the proposed algorithm.

抄録全体を表示

Sometimes we have a system that can be expressed basically by independent variables, with some redundant variable groups to decide only small parts of the system respectively. If the constraints of these redundant variables in each group are not coupled with each other, namely these are no common variables, we call them as local constraints. Examples of local constraints are Euler parameter constraint and constraint of link mechanism of car suspension. If the system has only local constraints, it is inefficient to use the typical DAE formulation, which handles all the constraints simultaneously. The technique we explain in this paper has advantage in calculation time and also in the sense constraint stabilization.This paper gives a basic idea of the technique and its general formulation. Also two examples are explained which we used to confirm the effectiveness of the technique. We got a good result of constraints stabilization.

抄録全体を表示

The paper illustrates a geometric approach to Lagrangian mechanics for nonholonomic constrained systems with a nonconservative force field. We first demonstrate a regular Lagrangian system for a conservative mechanical system in the context of variational principle of Hamilton and also that a nonholonomic mechanical system can be formulated on the tangent bundle of a configuration manifold by using Lagrange multipliers in the context of the induced symplectic structure. Then, we illustrate the case with a nonconservative force field and we finally show an intrinsic formulation of a nonconservative mechanical system with nonholonomic constraints by Lagrange-d'Alembert principle.

抄録全体を表示

The stability of translating flexible beam that passes through the elastic support is investigated. The instability of the beam is observed as the axial moving velocity increases from numerical simulation results. It is clarified from the consideration with the rigid beam model that the increasing of mass and damping coefficient ratio of the support yields negative damping effect of the system and the increasing of damping coefficient and stiffness ratio of the support yields negative stiffness effect of the system as the axial moving velocity increases.

抄録全体を表示

In this paper we discuss the motion of a tethered system. We considered the tethered system consisting of a very flexible body (the tether) and rigid bodies at one end as our analytical model. A flexible body in planer motion is described using the Absolute Nodal Coordinate Formulation. The combination of flexible body motion and rigid body motion is performed and interaction between them is discussed. We performed experiments to investigate the fundamental motion of the tethered system and to evaluate the validity of the numerical formulation. We conducted experiment of the motion of the tethered system with a rigid body in microgravity space. The numerical solutions using the proposed methods for modeling and formulation for the tethered system are in good agreement with the experimental results.

抄録全体を表示

This paper dealt with the analysis and evaluation of crucian fishing rod under fishing. At first, simulation software is constructed by using multi-body dynamics technique. Then fishing force when the crucian is fished is measured in real fishing in order to obtain the input data of the simulation. Next a fishing, that is, fishing rod-line-float-weight and fish system, is constructed for simulation and it is certified by some simulations. Then three fishing rods which are designed by feeling object oriented optimum design are simulated for throwing up motion and rod-line-weight-float and fish system and the fishing rods are evaluated from view point of feeling.

抄録全体を表示

In this paper, coupled vibration between the isolation table and the load is modeled. First, we prepared the FEM model of the isolation table with load. If to control a structural vibration is a purpose,it needs to reduce FEM model order. We use the extended reduced-order physical model (extended model) to reduce order from this FEM model. The extended model is developed for the control of the motion and vibration. This paper reported that the extended model has expressed well the correct natural frequencies and correct frequency responses by composing.

抄録全体を表示

This paper concerns the retraining of learning support vector machines (SVMs) that are trained to classify abnormal operating conditions of mechanical systems. Detection of the emergence of new data classes is mainly discussed that can trigger reconstruction of the training data set and retraining of the SVMs to obtain updated discriminants. In our approach, two self-organizing maps (SOMs), one with short term memory representing the current tendency and the other with long term memory representing the acquired knowledge, are used to detect the changes in the data structure by mapping the reference vectors in the long term SOM onto those in the short term SOM. A simple example using the data collected from draw-texturing machines is provided.

抄録全体を表示

The diesel engine has a high thermal effiency, but the serverity of emmision regurations is increasing. In such a circumstance, various exhaust decrease devices is studyed. But sevral exhaust device is affected by a fuel property. In this study, we wxamined possibility of fuel kind distinction by a neural network work system useing diesel fuel, kerosene and heavy oil. The neural network work system was able to give correct answers more than 80% by learning over 5000 cycles.

抄録全体を表示

This paper deals with a diagnosis of machine structures by detecting local abnormalities of measured signal through the harmonic wavelet. In this paper, the harmonic wavelet was utilized to detect the abnormalities of the signal. It was necessary for the harmonic wavelet to remove the end effects and reduce the obstructive noise in order to implement the diagnosis effectively. The authors proposed a method to remove the end effects. As a result, it was made clear that the harmonic wavelet detect the local abnormalities arising from the fatigue crack of crack length 1.07mm.

抄録全体を表示

A location estimation of an impact point on a board by neural network has been investigated. The neural network which has input units for the impact response spectrum and output units for its impact location is constructed. It is shown that the impact location can be estimated from an unknown impact response by the neural network.

抄録全体を表示

Bolted joints sometimes suffer bolt loosening and may sometimes induce accidents. Therefore, bolt loosening detection techniques are essential for many machines and structures having bolted joints. Authors have proposed a new bolt loosening detection sensor using a natural frequency of a thin plate and validity of the sensor is shown by experimental results. However, the sensor is not sensitive in high axial tension condition in other words, early stage of bolt loosening. In this paper, the mechanism of natural frequency change of the sensor induced by axial tension change of the bolt is considered with numerical and experimental results and two sensitivity improvement methods, using conical spring washers and size change of the sensor are studied. As a result, conical spring washers change the contact condition on sensor surfaces and improve sensitivity in early stage of bolt loosening.

抄録全体を表示

Because the reliability falls remarkably when the damage occurs to a structure by corrosion or looseness of a bolt, it is very important to detect the damage at its early stage. In a general structure, the detection of the damage is difficult from the viewpoint of following; (a) a structure is supported at plural points, (b) the damage is easy to occur at a support, (c) it is necessary to estimate how much damage occurred at which point in detecting the damage. In this study, we focused our attention on structures such as bridges supported at multiple points and suggested technique to identify the support condition and parameters of a member of structure and got a good identification result.

抄録全体を表示

The time reversal processing for the measured sensor signal can be applied to detect not only thestructural damage but also the impact loading of the host structure. In this study, a model based impactdetection method for the structural health monitoring is proposed. The impact identification capability of thenumerical time reversal processing is demonstrated by using a rectangular aluminum plate with nine surfacebonded piezoceramic sensors. The illustrative numerical simulation results indicate that the proposed methodcan be successfully identifying both exact impact point and time.

抄録全体を表示

We developed a monitoring system which enables monitor of plant equipment at low cost without construction of new signal cables. This system transmits the CCD camera image and wireless sensor data, which are vibration, and hand-operated valve position using established signal cables. This system uses a limit switch cable which detects opening and closing of a motor operated valve (MOV) and superimposes the CCD camera image and the wireless sensor data on the voltage signal of the signal cable of MOV by modulating these monitoring signals. The monitoring signal is separated with the voltage signal, and is demodulated and is displayed as the image and vibration data. It was clarified that this system can transmit the monitoring signal without influencing detection of opening and closing of MOV.

抄録全体を表示

This paper deals with extension of applicable area for the linearized equation of motion of spinning tops on the table which has been derived more than ten years ago by the auther. At first, the linearized equation which is only second order with complex number coefficients is again introduced. Friction torque is supposed to be viscous type and the coefficients can be expressed using heights of gravity center and radius of curveture at contact point. Applicability of the equation is limitted to the narrow region. In this paper, if, angular momentum vectors are sufficiently large and close to the zenith direction, it is shown that the attitude behavior can be described using the azimuthal equidistant projection. Two examples which are horizontally-suspended tops and the boiled eggs inclined more than about 45[deg] are shown.

抄録全体を表示

To decide the automobile fundamental parameter such as wheel base , the center of gravity , and wheel rate , we approached from the estimation of function using the quality engineering execution , we search the best design parameter combination considered the quantitative decision of the auto mobile dynamic performance and robustness against the surround change like running load. From the sensitivity analysis against each parameter's performance we'll control the property of the performance. Using the ADAMS, commutate the experiment with automobile dynamic running simulation ,we realized efficient CAE design system.

抄録全体を表示

This paper describes a study of bending vibration of a railway vehicle carbody by FEM. Railway vehicles with lightweight carbody have some natural modes of bending vibration in the high sensitivity frequency region for humans. Therefore, suppressing the bending vibration is necessary to improve the riding comfort. However, their vibration shapes are complicated, so it's difficult to calculate the effect at design process. The authors have developed the FEM model that is composed of whole carbody supported by air springs, and the simulation is carried out to calculate natural frequencies, mode shapes and frequency response function. The results show that it is able to evaluate the vibration mode characteristics of actual railway vehicle using the FEM model.

抄録全体を表示

Animation is greatly useful for understanding dynamics. Using animation for the result of simulations by changing parameters gives you a link over your experience and even to an unknown area. In this research,we propose a web-based site that has an Education Support System for representative Dynamics problems by using Java Applet which runs on common browser software and enables any one who can access to the internet to study by using this system.

抄録全体を表示

Damping properties of polymer-porous ceramics composites were discussed. Many systems in the mechanical engineering field are faced on the limitation of noise and vibration control. Vibration can not be controlled completely by mechanical methods, such as the conventional air damper, an insulator of a high polymer and computer controlled noise reduction system. High damping capacities of structural materials are required for precise vibration control. Polymer widely used as damping material has high damping capacity but low rigidity. To improve rigidity of polymer, ceramics with high rigidity and polymer were combined. The polymer-ceramics composites were made using Al_2TiO_5-MgTi_2O_5 solid solution and acrylic resin. The composites have high damping capacity(Q-1=0.03〜0.04) and high rigidity(E=50〜60GPa), and damping capacity was higher in the addition of low frequency.

抄録全体を表示

In Modal curve fitting methods, several kinds of weighting function were proposed to minimize the norm of error. However, Using a same weighting function for a set of all FRFs of a test structure often makes FRFs of some measurement points be fitted with good accuracy but other ones be not. In this paper, the authors propose the combination use of various kinds of weighting functions in modal curve fitting methods to deal with the measurement data of actual and complex mechanical systems. The proposed method automatically selects and applies the most appropriate weighting function to the FRFs of each measurement point. This method allows the modal curve fitting method to put better curve fitting results out.

抄録全体を表示

This paper investigates statistical variations occurring in the dynamic characteristics of structures and the way to simulate the variation by using eigen properties. First, accelerances of about 100 steel-cans are measured and the statistics of the measured accelerances and the modal properties on some orders are evaluated. Next, a nominal FE model based on one of the steel-cans tested is built through the comparison with the modal properties determined by the experimental modal analysis. The modal properties such as natural frequencies and modal damping ratios are considered to have the uncertainty. The variations on natural frequencies and modal damping ratios of the measured accelerances for the 100 steel-cans are evaluated. It is observed that these distributions follow the normal distribution approximately. As a result, it is shown that the population of the accelerances calculated by the FE model under the normal distribution based on the identified distributions is similar with the measured accelerances. The other distributions for expressing the variations of modal properties are also discussed.

抄録全体を表示

In order to control vibrations of machinery, it is very important to grasp the dynamics characteristic of the systems. Modal analysis is widely used as a basic technology for machine design. The impulse excitation method is often used from handiness in the vibration test. However, it has some problems. For example accurate excitation is difficult, and the result is influenced by the individual variation, etc. The identification method based on the subspace method is proposed, and the modal parameters are identified and compared with those of conventional method.

抄録全体を表示

This paper presents a procedure for the analysis of natural frequencies of finite element models with uncertain parameters. The uncertain model parameters are modeled with fuzzy numbers and then the uncertain natural frequencies are calculated by a fuzzy approach based on interval arithmetic. To obtain accurate intervals of natural frequencies, the interchange of mode shapes must be detected accurately. For this, a mode identification technique based on the MAC-value is proposed. The examples show that the procedure accurately produces the ranges of natural frequencies using the mode identification technique. In addition, the MAC-value can be used as an indicator for the proper number of α -cut levels.

抄録全体を表示

Many of the theoretical development in the area of control system design based on the system states assume that the system state vector is available for use by the control scheme. In order to exploit these control strategies, a suitable estimate of the state vector must be constructed for use in the original control law. This paper proposes a modified Utkin observer for estimating modal coordinates of structural vibration for the purpose of the vibration control. The original Utkin observer is constructed by the concept based on the sliding mode control theory and has robustness against certain class of uncertainty by virtue of the discontinuous input. The Utkin observer with the robustness would be improved to have much more stability by adding a negative output error feedback term to the observer. This consideration results in the modified Utkin observer.

抄録全体を表示

This paper addresses the design method of spatial filter for suppressing modal observation spillover.To eliminate the several selected modal amplitudes from structural vibration responses, a kind of modal filter is introduced.This filtering methodology can be realized by a small number of sensors, relative to the number of dominant modes in target frequency range. The method is validated by applying it to a beam structure.

抄録全体を表示

This paper describes the method of estimation of restitution characteristics of golf clubs by energy transmission ratio to each mode. For this method, it was shown that rigid body modes of the club influence the restitution characteristics greatly and under the constant of energy club and ball have before impact, restitution was better as increase of the mass of club head or decrease of the length of club shaft, and, sweet spot expanded when the mass of club head increased.

抄録全体を表示

The discrimination can not be attempted concerning the flight-distance, since the standard has been determined the performance of the golf-club at present. Therefore, it begins to notice the movement that the discrimination of the performance of the golf-club will be attempted in feeling merit of the batting sound recently. In this study, the prediction of batting sound of golf-club is done by the method for calculating to begin with, velocity potential using eigenvalue data by calculation modal analysis of finite element method. Next, the comparison examination of sound measured actually and sound calculated by the calculation is carried out.

抄録全体を表示

The accurate prediction of the sound power radiated from complicated structures, whose precise models are practically difficult to be made by the finite element method, is performed by an experimental-based approach combining impulse vibration testing and the boundary element method. This approach is applied to a small boat hull comprising of some panels with some longitudinal bending stiffeners and ribs as a basic research work in the series of a research for establishing an integrated analysis and optimization of mechanical systems to be assembled some components such as boat hulls and outer engines by means of using both experimental and theoretical modeling. It is verified that the predicted sound power level radiated from the hull is in a good agreement with an experiment. The parts of the hull radiating the noise dominantly can be identified.

抄録全体を表示

The technology of the smart structure system is expected as the indispensable important technology in the future advanced mechanical system, For example from MEMS to the space structure. Though a smart structure system has utility, application to the mechanical structure system and realization are delayed. A research and development trend outside the country about the smart structure system was introduced, and it referred to it about the factor that realization was delayed in this paper. Moreover, cooperation with the housing industry and the robot industry was mentioned based on the internal affairs, and the vector for the realization of the smart structure system was proposed.

抄録全体を表示

This paper presents the sensing and localization of impact force using the PNN-PZT (Pb(Nb,Ni)O3-Pb(Zr,Ti)O3) piezoelectric fiber with platinum core. In the former study, the cored piezoelectric ceramic fibers have been applied to airflow sensors. In this study, a composite smart board with 4 embedded piezoelectric fibers was fabricated and output signals of the fibers were recorded when impact force was applied to different point of the board by an impact hammer. The time history of the impact force was measured with the signal from the impact hammer. A neural network, trained based on the signals of impact hammer and the piezoelectric fibers when the composite board was hit at seven different point, was used to identify the impact position. The identification results of the impact force at untrained position show the effectiveness of the method using a neural network and embedded piezoelectric fibers for impact localization.

抄録全体を表示

This paper deals with damage detection and vibration control of a smart structure. A finite element model of a cracked beam is established. This model is applied to a cantilever beam and the natural frequencies are determined for a different crack length and locations. This study proposes a method for the crack identification when the vibration of the beam is suppressed by using active control. Furthermore, we design the gain-scheduled controller considering both the crack length and the location. The efficiencies of our crack identification method and the gain-scheduled controller design are verified by simulation and experiment.

抄録全体を表示

A novel method of hybrid vibration suppression using piezoelectric materials is proposed. It combines bangbang active control and energy-recycling semi-active control. The hybrid method saves actively supplied energy and is thus a low energy-consumption vibration control. Its effectiveness in suppressing vibrations was proven in numerical simulations and experiments using a 10-bay truss structure. Moreover, an innovative method to prevent undesired control chattering is proposed to further save energy supplied from the external source.

抄録全体を表示

Recently, low noise gears without lubrication are required for business machines and robots, because they are used in open space. The present article provides a new type gear consisting of steel and resin (called Delrin-100), which has good lubrication characteristics. Production processes are presented for the gear, and its characteristics are investigated. It is ascertained that the strength of our gear is greater than that of a plastic gear, and noise of our gear is small in comparison with plastic gears. The design method is presented, and effects of friction on the position control is also investigated.

抄録全体を表示

The new sealant layer is presented, which is easier to include into the manufacture process of the tire in comparison with the previous research. The performance of the present tire was investigated, and it was clarified that there was no air leak when nails broke it. Vibration characteristics of the present tire were analyzed theoretically and experimentally, and the effects of the sealant on the road-ability and the road noise were investigated. Using the analysis, it is shown that vibration transmissibility decreases in the present. The impact characteristics are also discussed. The transmissibility is also decrease when the impact load applies to the tire, and load noise is also decreased

抄録全体を表示

An analysis of the first resonance mode of piezoelectric fibers with metal core is carried out, and a method to estimate their piezoelectric properties is proposed. The modeled structure is first a hollow ceramic cylinder. The importance of radial stresses is investigated. Correlation with Finite Element Modeling is presented to validate the analytical approach. The effect of the insertion of a metal core is then presented through the calculation of the electromechanical coupling factor of the whole fiber after a homogenization of the metal core and the hollow cylinder. It is found that there is an optimal diameter at which the pseudo-lateral (length vibration) coupling factor is maximum. Finally the model is simplified, and a characterization procedure -called upward approach- of actual fibers is given. FEM is used to predict the resonance frequencies of a fiber with platinum core. The upward approach is then applied and the obtained piezoelectric ceramic parameters are found to be quite close to the real parameters, i.e. errors inferior to 7.9% in the worst case.

抄録全体を表示

Semi-passive control has been successfully applied to vibration control in the former studies. In this study semi-passive control using piezocelamics is applied to noise isolation . In semi-passive control, the piezoceramics are connected to a shunt circuit including an inductor and switching device. The voltage of piezoelectric element generated by structure's vibration is inverted when the voltage reaches maximum. Consequently the system becomes a velocity feedback, and thus, the damping of the mechanical energy of structure is obtained. Semi-passive technique is compared with passive and active approaches in terms of control effectiveness, robustness and validity for random noise excitation

抄録全体を表示

This paper proposes a multidisciplinary design optimization approach of smart structures for vibration and sound suppression. The smart structure consists of panel with one fixed end, two piezoelectric actuators and control system. The control system is designed according to the H2 specification with a reduced-order modal model derived from FEM and modal analysis. The sound pressure level of sound radiation from the vibrating panel is calculated by BEM. The design problem for improving the H2 performance is defined, and then the piezoelectric actuators and the control system are simultaneously optimized by the presented approach, resulting in an enhanced performance for the vibration and sound suppression.

抄録全体を表示

A wave absorbing control method using piezoelectric film sensor/actuator, namely quasi-waveabsorbing control which is based on relative displacement control, of a flexible thin-walled cantilever beam subjected to random displacement excitation is investigated. Vibration control experiment is performed with the triangular shaped sensor and the rectangular shaped actuator bonded on both surfaces of the beam, and velocity feedback control law which is expected to be most effective in the theoretical analysis is applied. Fixed boundary of the cantilever is subjected to limited bandwidth random noise excitation, and the relative displacement of the beam is measured. It is verified that good vibration control effects are obtained for the bandwidth containing three lowest vibration modes.

抄録全体を表示