This report presents a numerical method to investigate the frequency response of a rectangular plate. When we use the transfer matrix method to calculate frequency response of plates, exciting force is limited to a line force and applicable object is also restricted. For this reason, we propose a method to calculate modal parameters from free vibration analysis by using the transfer matrix method. Modal mass are calculated by numerical integration from modal vectors. We have applied this method to calculate the frequency response of plates. Comparing the results obtained from the proposed method and finite element method, characteristics of the frequency response have a good agreement with each other.

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The averaging method of elliptic type is proposed in order to obtain accurate periodic solutions for a nonlinear oscillator with two-degree-of-freedom with harmonic excitation and damping. Elliptic Jacobian cosine function (cn) is incorporated as the generating solution of averaging method. The stability analysis for the approximate solution obtained by the present method is also discussed. The numerical results for typical nonlinear oscillators are shown. The efficiency of the proposed method is illustrated by comparing its computational results with those obtained by the shooting method.

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This paper shows new method to describe forced vibration response of multi-degree-of-freedom system. This method is possible to obtain transmissibility of vibration by manipulating equation of motion without the issue of eigenvalue. The transmissibility we obtained can describe resonance curve in any parameter of multi-degree-of-freedom system. It takes the form of the fraction. The root of the denominator shows the resonance point and root of the molecule shows the anti-resonance point. It is not considered that it's property to depend on temperature, distortion and frequency. We experimented in order to verify this method. And we compared calculation curve with experimental values. We find that the tendency which is identical for both was obtained. The result of comparison shows that there is validity in this method.

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This paper deals with the parameter dependency analysis of natural frequency of continuum with variable multi-parameter. In the design phase of a component of mechanism, it is important to know how several design parameters such as its dimensions and loading force affect its natural frequencies. The modal hypersurface which is a set of a target natural frequency of variable multi-parameter system is firstly defined. The modal polytope which includes the corresponding modal hypersurface and have two boundary hypersurfaces is secondly defined. A new concept of the modal polytope analysis is further proposed. Proposed method reveals the continuous parameter dependency of natural frequencies with simple calculation. Example of a thin plate which has three variable parameters shows validity of this method.

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Wavelet autocorrelation function is proposed in this paper. After Cooley and Tukey developed the algorithm of fast fourier transform, the power spectral density is used in various field to obtain the frequency components of stationary signals. Autocorrelation function is derived as inverse fourier transform of the power spectral density. In the autocorrelation function, the noise components of target signal are reduced, although the periodic components still remain. In this study, autocorrelation function of wavelet transform is proposed for time series analysis of nonstationary signal, and its ability for noise suppression is investigated.

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We propose the method for analyzing the envelope functions of random signals using absolute value function. Some signals observed from machines, structures and earthquakes are expected to have various envelope functions and it is important to analyze them. However, if there are additional noises in the signals, the distinction between their envelope functions and noise components is difficult by the conventional approaches. In this study, we apply the method to two types of signals with noise and investigate its ability to extract the envelope functions from random signals.

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Nonlinear vibrations of elastic structures carrying two cylindrical tanks partially filled with liquid is investigated when the structure is subjected to horizontal harmonic excitation. When a ratio 1:1:1 of the tuning condition is satisfied between the natural frequencies of the structure and sloshing in the liquid tanks, modal equations are derived considering the nonlinearities of the hydrodynamic forces. Then, van der Pol's method is employed to determine frequency response curves. The numerical results show that whirling motion and translation motion of the structure appear depending on the swirl motion of sloshing in two tanks in the same and opposite directions, respectively. They include the vibrations at constant and modulated amplitudes. The validity of the theoretical results was confirmed by the experiments.

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This study shows the hysteresis properties of a cantilever beam under the influence of magnets. In a previous report, one of the authors studied mechanism of vibration control by the pulsating force. This control method needs two or more stable solutions because the essence of this method is the jump phenomenon from large amplitude wave to small one. This report examines the behavior of the beam under the influence of electro and neodymium magnets in order to search the hysteresis conditions. The results of the experiments show that the control method can reduce amplitude of the cantilever beam when neodymium magnets stick to the beam.

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Analytical results are presented on chaotic vibrations of a post-buckled beam constrained by a nonlinear axial spring under axial and lateral excitations. The nonlinear axial spring has a weak secondary nonlinearity. Equations of motion of the beam are derived including the term of parametric excitation due to the axial excitation. Nonlinear periodic responses are calculated with the harmonic balance method. Time progress of the beam, including chaotic response, is calculated with numerical integration. Effects of the amplitude and phase of the axial excitation are examined on the nonlinear periodic responses and the chaotic responses of the beam.

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Experimental results are presented on chaotic vibrations of an annular plate with a concentrated mass in this paper. To investigate effects of the mass on chaotic vibrations of the plate, chaotic responses are inspected by time histories of multiple positions, the Fourier spectrum, the Poincare projection and the Lyapunov exponent. Furthermore, principal component analysis is adapted on the chaotic responses of the plate to confirm modal contributions of multiple vibration modes. The chaotic response of the plate without the mass shows irregular motion accompanied with traveling waves. As the concentrated mass increases, the chaotic response with irregular motion of traveling waves decreases to the quasi-periodic response.

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The ball balancer has been used for the vibration suppression method in rotor system. It has a superior characteristic that the vibration amplitude is reduced to zero by it at the rotational speed range higher than the major critical speed. However, the ball balancer may cause a self-excited vibration when the balls rotate in the disk, and this self-excited vibration results in the large amplitude vibration. In this paper, the occurrence region and vibration characteristics of the self-excited vibration are investigated. The theoretical analysis is performed and a set of the fundamental equations governing the self-excited vibration is obtained. The influences of the parameters, such as, damping of the ball motion, gyro-effect of the system, ball mass, radius of the ball orbit, and the system nonlinearity are explained. As the result, it is shown that the damping of the ball motion and the ball mass have the effect on decreasing the occurrence region of the self excited vibration.

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This paper deals with the squeal phenomena generated in a floating type of car disc brake unit. The squeal is caused by the coupled out-of-plane vibration modes among rotor and caliper due to Coulomb friction. As a countermeasure, a dynamic absorber was applied to the leading side and the trading side of the inner caliper experimentally. And, the analytical model of the car disc brake system was set up. The dynamic absorber was applied also analytically. It was made clear that the natural frequency of the dynamic absorber should be tuned in to near the frequency of the squeal, and the squeal can be controlled even a damping is not put on the dynamic absorber. These results agreed well with experimentally and analytically.

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This paper presents experimental and analytical results about squeal on disk brake from the viewpoint of the pressure and stiffness distribution in the frictional contact surface between the disk and the pad. To clarify the influence of the contact surface, the simple system is used for squeal test instead of an actual disk brake, and the contact stiffness is measured. To clarify the mechanism of squeal generation, Surface-contact model based on the experiment results is examined. This model can reproduce the influence that the state in contact surface gives squeal though it has only three degree of freedom.

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Recently, the brake noise reduction is one of the most important environmental issues for railway passenger transportation. In this study, a friction-induced self-excited oscillation of a tread brake system was numerically investigated by using finite element models for the brake shoe and wheel. The study was based upon a dynamic instability analysis giving unstable coupled modes of the brake shoe under the contact and Coulomb friction between the elastic shoe and rigid wheel. It is found that the brake squeal occurs when the two vibration modes of the shoe were coupled with the increase of the friction coefficient. The illustrative numerical results demonstrated the capability of the prediction of the brake squeal.

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In this paper, vibration in wet friction systems with paper-based friction materials as seen in wet clutches in automatic transmissions was investigated theoretically and experimentally. The experiments were conducted under various conditions of lubricating oils, surface velocities and normal loads. It was shown that the vibration phenomena in this wet friction system depended greatly on the relationship of the friction force to the relative velocity characterizing lubricating oils. It was suggested that the vibration phenomena could be classified using the relationship of the relative velocity between the sliding surfaces to the surface velocity of one sliding surface.

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This sheet deals with characteristics of the oblique impact system, which is composed of the ball and flat surface. The impact system is modeled by both a nonlinear spring and a nonlinear dashpot using Hertz's contact theory. This model is applied to the oblique impact system of ball. The characteristics of the oblique impact were obtained by using this model. The results show that the stiffness of impact system was not affect ed the spin rate and the ratio of angle. Also, in the case of increase the coefficient of restitution, the spin rate was increased and the angel of reflection was decreased.

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Authors have been examining the restitution property of metal balls of same diameter and same materials to understand the impact phenomenon of the object. In this research the impact experiments on same diameter and different material spheres were conducted for aluminum (A5052) sphere and steel (SUJ2) spheres, and the restitution property was examined. The coefficient of restitution of aluminum and SUJ2 steel, decreased exponentially with the impact velocity. Finite element analyses were done by using the stress-strain relations obtained from the static compression test and dynamic compression test. The analytical results correspond well with the experiment results.

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This paper deals with the response analysis of impact vibration in continuous system excited by periodic displacement with arbitrary functions. A system of steady vibration in a cantilever having an attached mass at free end is considered. The cantilever has structural damping in the beam, and it is being put in the viscous fluid with hydrodynamic drag. The attached mass collides elastically with the coil spring clamped on asymmetrical faces when the amplitude of mass exceeds the clearance between the coil spring and the attached mass. Then, the restoring force is assumed to be characteristics of a piecewise-linear system. For such a system, the beam undergoes a nonlinear vibration when the attached mass collides with the coil spring. In order to analyze the resonance phenomena for the system, the Fourier series method is applied to obtain an exact solution for resulting vibration. The numerical calculation is performed to obtain the resonance curves. The numerical results show effects of the stiffness of attached spring and the amplitude of excitation on the resonance curves. The numerical experiments are also carried out to verify the numerical results.

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This paper deals with collision vibration in a mass-spring-system for two-degree-of-freedom excited by periodic force with arbitrary functions. The analytical model is steady collision vibration having two masses which one mass is subjected to an exciting vibration, and the elastic collision is done to another mass when amplitude of the mass exceeds than the clearance between upper mass and lower mass. Then the restitution force is assumed to be characteristics of an unsymmetric piecewise-linear system. In order to analyze the resulting vibration for harmonic, superharmonic and subharmonic resonances, the Fourier series method is applied to obtain an exact solution for resulting vibration. Next, following the theoretical analysis, the numerical calculations are performed to obtain the resonance curves. The numerical results show effects of the stiffness of clamped spring and the mass ratio on the resonance curves.

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Impact vibration of beam was treated as an example of the impact vibration of continuous system and following points were researched. (a) A number of modes to express the impact vibration phenomena sufficiently. (b) How affect a damping of the beams the impact vibration. The followings were made clear. (1) By adopting six modes, the theoretical results and the experimental ones agree well each other. (2) The damping of a higher mode strongly influences a bifurcation. (3) From the viewpoint of the engineering, the transition from periodic motion to chaos is interpreted as the grazing bifurcation.

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In this research, the optimal design aiming at designing the leg mechanism of a six-legged mini shovel, which can minimization the load of the oil-pressure cylinder and the flow rate of a hydraulic pump and maximize the movable range of the leg, was formulized. Firstly, the size of the leg mechanism and the chassis were decided, and a basic design of the six-legged mini shovel was carried out. Next, the optimal configuration of the oil-pressure cylinder of a leg mechanism was designed by the statics analysis of a leg output. Furthermore, a design variable, a evaluation function, and optimization method were determined, and the optimization of a leg mechanism was formulized. Finally, walk analysis by statics was carried and the effectiveness of this research technique was clarified.

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In this paper, we suggest a new control method for Steer-by-Wire vehicle. This method is based on optimal control. Generally, nonlinear optimal control requires complicated calculations and an assessment of second degree order with respect to input. To solve this problem, we apply optimal control of mechanical system based on energy equation. And we confirm on the simulation that this method has robustness for the arithmetic error of the slip velocity.

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The noise and vibration of industrial sewing machine is increasing as it is used in high rotation speed. And analysis with the traditional linkage analysis is difficult to determine excitation force for the noise and vibration of high-frequency region. This research is to analyze the excitation force of high-frequency region. And the excitation force of high-frequency region is analyzed with addition of non-linear element in link mechanism.

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This paper presents an algorithm for multi-objective simultaneous optimization of topology and shape of two dimensional framed structures. The computation process of the present method consists of two steps. First, the Pareto-optimal fronts for topology optimization are calculated by using genetic algorithm that was developed in our previous work. Secondly, the Pareto-optimal fronts for shape optimization are calculated from the Pareto-optimal solutions obtained above by using simulated annealing introduced the concept of a rank-based technique. The effectiveness of the present method concerning the convergence and diversity of the solutions was verified by the results of the numerical examples.

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It is essential to suppress vibrations of robots in the industrial area. Many researchers have been studied these problems from the control system design. In this paper, an example of optimum structural design for belt driving robot is proposed based on the simultaneous optimum design for control and structural system. First, the dynamic response of a robot arm is measured. A mathematical model with the consideration of the elastic characteristic of belt is constructed to simulate the motion of the arm. Finally, by using the structural modification model in which the mass distribution of the arm is changed, the optimum design is searched such as to minimize the objective function obtained from the residual vibration.

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Modal differential substructure that can quickly predict effects of structural modifications has been proposed by the author. This method utilizes simulation results of the model before the structural modification. Because the method does not require the user to decide the section of structural modification beforehand, the user can determine the section after checking the calculation result.In a certain case, however, where the model has to handle very many modes, the eigenvalue problem becomes insoluble due to singularity of the mass matrix. This report elucidates the reason of the problem and shows a procedure to avoid it.

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This paper shows two identification methods of propagation characteristics of pulse wave in viscoelastic duct. One method identifies material parameters of viscoelastic duct by measuring pressures at three points and flow volume at one point. The other method identifies them by measuring pressures at four points. Material parameters of the same silicon tube were calculated by two methods. And reasonability of two proposed method was confirmed by comparison of two calculated material parameters.

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In this paper, a method to identify the geometrical shape and the location of the defect embedded in a concrete structure by processing the thermal image of the structural surface acquired by infrared thermography is presented. In the proposed method, the structure is modeled as a homogeneous infinite plate whose boundary condition on the observed surface is known. A layer-by-layer inverse analysis using a regularized interlayer transfer matrix based on 2D Fourier transform is carried out to obtain the sharper image of the defect as well as the depth of the damaged layer. The estimated depth information mapped on the image plane has resulted in a depth image which can display the shape of the defects as well as their depth simultaneously. An improved method introducing equivalent virtual heat sources that prevent the "boundary artifact" caused by the heat flux across the image boundary is presented.

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Because in many cases damage of mount could be assumed to reduce a spring constant, we estimated spring constant of each engine mount by solving inverse problem to detect a damage of mount in this paper. Finally, we can identify spring constant of mount in the vertical direction with high accuracy.

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Japan is a seismic country and many structures were built in the highly economic growth period, then deterioration of structure becomes an important problem. So the structural health monitoring is strongly desired. Generally stiffness of the structure decreases when the structure is damaged by the load such as earthquakes. If this parameter can be estimated, the damage level of the structure can be evaluated. In this paper, real-time health monitoring strategy using multiple model method is proposed. Only the acceleration of the top floor is used for estimation. The estimator consists of two procedures. In the first step, the damaged story is detected. In the second step, the stiffness of damaged story is estimated. Simulation studies and experiment are conducted for four story frame structure, and the effectiveness of the proposed algorithm is examined.

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Four stroke reciprocating engine is a lot of internal combustion engines which frequently used in industrial world. The engine used at steel manufacture and chemical plant factory is maintained based on CBM to keep the manufacturing efficiency. Therefore, a more highly accurate equipment diagnosis technology is desired. The purpose of my work was to have experimentally examined abnormal state of reciprocating engine and possibility of identification of abnormal signal element generated in that case. This paper reports on my work, the signals on normal state and abnormal one of the diagnosed engine obtained by acceleration pickups, and AE sensors, a condenser microphone have been, and analyzed. As a result, abnormality that occurred in the reciprocating engine has been reproduced, the basic finding associated with the characteristic of abnormal signal has been obtained. The results indicate that presumable abnormality of reciprocating engine.

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Continuous operation of rotating machinery with a rotor crack is a risk condition since the rotor crack grows rapidly and may fail causing a catastrophic accident. This paper investigates the finite element model of the rotating shaft with an open crack. The analytical method of the natural frequencies of such a rotor system with an open crack is developed. By comparing both the theoretical and experimental results of the natural frequencies, the modelling of the rotating shaft with an open crack is improved. Furthermore, the accuracy of the developed crack model is confirmed in the rotating test.

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Differential pressure transmitter with an orifice is widely used as a major field flowmeter. A major drawback of this flowmeter at the operation site is the blockage of the impulse line. Hence, applying the delay of pressure transmission to the differential pressure transmitter by this trouble, this paper develops a diagnostic method of the impulse line blockage with multi-sensing differential pressure transmitter. In this investigation, a diagnostic method using the shift of phase difference between upstream and downstream pressure of the orifice can diagnose the gradual impulse line blockage at the water and air line.

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The on-line performance monitoring of a heat exchanging process using water and steam, which is one of the key components of distributed energy supply system, has been develop on the basis of a theoretical model. By using an input-output model of the process, this performance monitoring first estimates output process variables and heat exchange performance of the process in response to the variation in measured input process variables. These estimated values are then compared with the measured ones for the on-line performance monitoring. Its effectiveness under transient state has been confirmed by the numerical analysis. The result confirmed the sufficiency of the estimation accuracy of the output process variables and heat exchange performance under transient state and the detection capability of the deterioration of the heat exchange performance.

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Recently smart structures using piezoelectric elements as sensors and actuators of vibration control have been studied. Design and analysis of such smart structure is a multidisciplinary problem that consists of mechanical, electrical and control problem. Therefore, multidisciplinary modeling technique is desired for study of smart structure. However, conventional model of mechanical system is incompatible with model of electrical system. Block diagram can model mechanical and electrical system in generalised form. However physical quantities are treated just as signals and it is not easy to understand physical phenomenon from signal flow in block diagram. Functional model is proposed as a modeling method of multidisciplinary system and can solve the above mentioned problems of conventional models. Functional models of basic elements of mechanical and electrical system, for example, mass, stiffness, capacitor, inductor and DC motor have been developed. However, functional model of piezoelectric element has not been developed. In this paper, functions of piezoelectric element are considered and functional model of piezoelectric element is developed to apply functional model to smart structure system. Energy flow in the energy regenerative vibration control system that have been studied by authors is simulated by functional model and the result is compared with the result of the previous simulation using equivalent circuit model.

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In hard disk drives, vibration suppression is very important to boost the servo performance for achieving the enhanced density of the disk and following precision of the system. It has been expected that technology of smart structure will contribute to the development of small and light-weight mechatronics devices with the required performance. This study proposes a new vibration control mechanism with smart structures technology in order to achieve significant vibration suppression in hard disk drive systems. First, modeling of the system is conducted with finite element and modal analyses. Next, the control system design and closed-loop simulation are performed with the proposed vibration control mechanism composed of piezoelectric sensors and actuators. Finally, a multidisciplinary design optimization on actuator location and control system is examined to enhance the closed-loop performance of the system.

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The head positioning accuracy of the hard disk drive (HDD) should be improved to meet today's increasing performance demands. Vibration suppression of the arm in the hard disc drive is very important to enhance the servo bandwidth of the head positioning system. In this study, the smart structure is introduced into the hard disk drive to suppress the vibration. The actuator location and the control system are optimally-designed using genetic algorithm (GA). Vibration control effect with the proposed vibration control mechanisms has been evaluated by some simulations.

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This paper proposes one of hybrid vibration suppression methods based on the passive one using piezoelectric elements and a LR circuit. A lot of hybrid methods have been proposed; however, most of them merely use both the active and the passive methods together. In contrast, large controlling force is generated in this method by amplifying the sensed voltage in piezoelectric elements using a sensor and an amplifier. Because the governing equations of the proposed method are also similar to those of the passive method, the optimum values of the circuit can be determined by simple formulations derived by the Two Fixed Points Method. The characteristics of the proposed method were investigated by theoretical analysis, and its effectiveness was verified by the experiment.

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To develop a high usability keyboard, operability of the keyboard was investigated by measuring electromyograph, recording finger movement by means of high speed camera and a sensibility test through surveying questionnaires. One of burdens which appear in the body during keyboard striking, is said to be tendovaginitis. This is caused by large stroke and heavy impact on a keyboard during striking. To lighten the burden, the authors made a new type keyboard of which stroke is less than 0.2mm. The keyboard can also be operated by small striking force. Sensibility experiment was conducted to evaluate the new developed keyboard and the result was used to upgrade the keyboard. Sensibility experiment for the upgraded keyboard was conducted to evaluate the operability of the keyboard by electromyographic measurement, finger movement recording by means of a high speed camera and sensibility test. The upgraded keyboard showed less physical burden but did not show high usability score.

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A drunken driving has been a big social issue. Combining the noninvasive pulse wave monitoring sensor and algorithm, we have devised a drunken-driver detection system. In this system, temporary changes in homeostatic mechanism such as peripheral circulation, which occurs after alcohol intake, were utilized. It has been verified that it is possible to detect the difference between a subject's normal condition and drinking condition by analyzing biomedical-signals such as a pulse wave and the second derivative of a photoplethysmogram waveform.

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The drowsy driving arisen from fatigue has come to be a social problem. As a preventive means of this situation, some systems which catch drowsiness and sleep prediction by detecting a driver's biological signals are proposed. However, there are few reports about noninvasive biological signal sensing devices. This is so that biological signals are buried in mechanical vibration input to a car. This sensing system consists of the air pack generating pressure, the condenser type microphone sensor detecting pressure and signal processing circuit part. The detected breathing and pulse wave took correlation with an optical finger plethysmogram measurement device.

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To clarify the changes of sympathetic nervous system(SNS) activity during the Japanese tea ceremony, we measured the heart rate change and respiration variability while an expert performed "Temae." In comparison to a preceding rest period, the R-R intervals of the heart rate became shorter and the variability of R-R intervals decreased during "Temae." Furthermore, respiratory frequency tended to increase and the respiration variability tended to decreased. Comparing the heart rate and respiration variability with motion of "Temae" observed in videos reveals that the variability of R-R interval and respiratory rate decreased during common actions. These results suggest that SNS activity increases at the common action during "Temae".

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To clarify the process from the sharp to the dull of Japanese Kitchen Knives (JKK), we measured the change of edge roughness, angle, and "shape" or "quality of sharpness" in JKKs while three women used the JKK continuously during 6 weeks. The edge roughness or angles of three JKK used continuously were rougher or greater, respectively, than these before using. In the "shape" and "quality of sharpness", there was no difference between three used JKKs, but the evaluation of the used JKKs were lower than that of unused JKK. These results suggest that changes of edge roughness and angles affect to the "shape" and "quality of sharpness" when JKK was used continuously.

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We developed a device that calculates and displays the center of gravity point and joint moments at the same time with motion. By using this device, stability and physical burdens can be checked with movements and dynamic consideration and understanding for the burdens outbreak are obtained. In the application of this Real-Time Analyzer to analyze the daily living activities such as lift up motion, push motion, and pull motion, we examined the most suitable method of motion with a few physical burdens.

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This paper showed that a very thin, flexible bending sensor was able to be composed by laminating a polymer piezoelectric film (PVDF film) and processing the electrode geometry appropriately. Moreover, the angle such as the elbow joints of the human body was measured with a developed sensor. A variety of electrode patterns are molded on the surface of a polymer piezoelectric film accumulated by the laser beam machining. It was experimentally clarified that problem of the bending deformation sensor developed before using PVDF film.

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A wearable sensor system for gait analysis is presented, which is composed of a combination of a six-axis ground reaction force sensor system with parallel mechanism and motion sensor modules using by gyroscope sensor and accelerometer. From output of the sensors, joint moment of the lower limb is estimated by applying inverse kinetics. Experimental study is carried out to evaluate accuracy of the proposed estimation system. Experimental results of the proposed system compare well with those of the conventional method which is a combination of 3D camera system and force plate.

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In this study, the method to infer the situation of child's downfall accident by computer simulation was constructed. In the simulation, child multi-body model based on real children's body dimensions and actual spiral stairs model were used. Objective function based on a fall point after the accident was determined and a response surface was constructed to estimate the relationship between the objective function and input variables of the simulation. The circumstances of pre-accident were inferred by using genetic algorithm. The method was applied to a real accident and the estimated situation approximately corresponded to the real accident. The method showed the possibility to estimate the accident circumstances in a real accident.

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Human voices are originated by vibration of vocal folds in larynx. This vibration is induced by the airflow that is expelled through glottis, and causes a series of the pulses of the airflow. These pulses excite vocal tract and bring about the passive resonance of the vocal tract in all voiced sounds. Therefore, detailed study of vocal fold vibration is believed to be important to elucidate mechanism of human phonation. Thus, in the present study, experimental analysis of this vibration was made to clarify phonation mechanism and seek better modeling of vocal folds, focusing on direct measurement of subglottal pressure and glottal velocity and simultaneous observation of vocal fold movement by means of a high-speed digital camera. The experimental results prove that subglottal pressure increases in closing phase of vocal folds and decreases in opening phase and high speed airflow just above glottis results in closing of vocal folds. This fact is important since it gives a crucial hint for better simulation model of phonation mechanism.

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