As it is difficult to measure low flow ranges with a vortex flowmeter, it is combined with a thermal mass flowmeter and they complement each other to make a "Hybrid Multi DELTA Flowmeter" of super wide flow range. By measuring wide ranges while restraining cost increase, the model is most suitable for utility gas measurements for energy saving.

View full abstract

An instrument based on the light extinction method was developed to measure the mass concentration of elementary carbon particles (dry soot) in diesel exhaust. The instrument uses a laser diode with 635nm wavelength as light source, and measurement tube with 770mm light length. The features of the instrument are raw gas direct sampling, 0.1second response time and wide detection range of 0.15 to 1000mg/m^3. The soot mass concentrations change dynamically depending on the variation in engine load and speed were measured

View full abstract

The state of heat loss from combustion gas to combustion chamber walls in an internal combustion engine can be evaluated from instantaneous surface temperature of the walls measured by thin-film thermocouples. For this purpose, measurement devices should ensure high accuracy and synchronize with the engine operation. On the other hand, the measurement circuit used needs to be noise-free and quick in response. Furthermore, meaningfully reproductive data must be generated from the data processing device. In this report, the authors' measurement system including all those devices is presented.

View full abstract

Both the low emission and fuel economy are most important in automotive technology. It is necessary to measure precisely the indicated mean effective pressure (IMEP), however, a lot of sampling data of the cylinder pressure are required for the calculation. In this paper the authors have proposed a simplified method for estimation of the IMEP, which utilizes the Fourier series transform. The new system is very effective even in the transient condition, as well as the steady state of engines, as the real time analysis for the response and accuracy.

View full abstract

A highly precise actuator which applied to a track following for a high density magnetic recording evaluation system was designed and developed. The actuator called the Nano-motion actuator (NMA) that was consisted of a displacement amplitude mechanism, which was composed of a parallel spring and a lever mechanism, and a layered piezoelectric element (PZT). A original NMA has a working distance of 12.6μm, the gain crossover frequency of 3.07kHz with the excessive load of 15g. In this paper, the XY-type NMA that consisted of the original NMA and a new translation type of NMA was designed. Moreover, we verified the positioning accuracy of the XY-type NMA in a X-Y plane and step responses for each axis. As the gain crossover frequency could reach to 1.0kHz for X and Y axis, respectively, the XY type NMA could realize high speed and highly precise positioning in the X-Y plane.

View full abstract

The separation of mixture consisting of copper and polyvinylchloride (PVC) was studied experimentally and analytically. The principle behind the separation technique is based on the difference in Coulomb force acting on the particles after triboelectric charging and induction charging. The electric field is produced between the electrode and the conductive conveyor belt. The separation tests were performed with chopped waste electric cables. The effect of electric field strength and triboelectric charging time on separation efficiency was investigated. It is shown that it is possible to obtain high purity and recovery.

View full abstract

A new type of concept, "a rocket plane system of a horizontal take off and landing from the water" has been proposed. To explore the possibility of this concept, various experiments using "POC (Proof of Concept)" models are being conducted. In this paper, a flight control system for a horizontal take-off and landing spaceplane is presented. Especially we refer to the design method of a guidance and control system. To verify the performance of the flight control system, the Monte Carlo simulation of nonlinear 6-DOF aircraft model was carried out. As a result, it was confirmed the flight control system has good performance.

View full abstract

A ball balancer is a balancing device where two balls inside a hollow rotor locate automatically to eliminate vibrations in the rotational speed range higher than the major critical speed. However, it has following defects. First, the amplitude of vibration increases in the lower rotational speed range. Next, almost periodic motions with large amplitude occur due to the rolling of balls inside rotor in the higher side of the major critical speed. Due to those defects, the automatic ball balancer have not been used widely. In this paper, we propose to use the vibration suppression method utilizing discontinuous spring characteristics together with a dynamic ball balancer to overcome these defects. The validity of proposed method is confirmed theoretically, numerically and experimentally. The results show that amplitude of vibration can be suppressed to a small amplitude in the vicinity of the major critical speed and the zero amplitude in the higher rotational speed side.

View full abstract

This research aims at reducing unbalance vibrations, which have bad influences on the performance of a rotary machine, on the resonance frequency for the overhung rotor system with actively flexible pedestal. Therefore, in this model, the control system is designed by using the robust control theory. The numerical simulations about the over-hung rotor system containing the control system are performed, and the robust control effect for the vibration of the overhung rotor is examined.

View full abstract

This paper studies on the transient vibration of bearing under runup and rundown of flexible rotor. The rotor / journal bearing system is modeled by FEM and integrated by Wilson's θ method in order to obtain transient amplitude and phase angle. Followings are concluded; the effect of transient response on the balancing is not so big for low increasing rotating speed and high damping, the fixed phase angle for fixed rotating speed which is not move by increasing and decreasing rotating speeds exists and it is very useful for the balancing of a flexible rotor, transient balancing is possible if data of both influence coefficients and unbalance response obtained by transient rotating speed is same. Error analysis of balancing weight and vibration after balancing was done for the case of different increasing speed of influence coefficient and unbalance response.

View full abstract

In this paper, a phase margin, a gain margin, a sensitivity function, a maximum singular value of sensitivity function matrix and a damping ratio are taken up as indices which evaluate the stability margin of a rotor levitated by active magnetic bearings. The definition of the stability margin in this research is how far away the gain margin, the phase margin and the reciprocal number of the sensitivity function are from the critical point (-1, j0) in a polar plot. The stability margin distance is proposed to unify above-mentioned indices. We have estimated stability of a rotor-AMB system by these five indices and investigated relations among the indices.

View full abstract

In industrial rotational machinery, it has been required that a long span and a high-speed rotor are designed in order to improve efficiency and reduce costs. In concerning many flexible rotors, the 1st bending critical speed and the 2nd bending critical speed have been passed, but never the 3rd critical speed. In this study a flexible rotor having the 3rd bending critical speed within the rated speed was designed, and was tested to pass the 3rd bending critical speed, owing to fine tuning of AMB controller and accurate balancing method.

View full abstract

This paper proposes a new modeling technique and control system design for flexible rotors using active magnetic bearings (AMB) to pass through many critical speeds and fulfill high-speed rotation. To achieve this purpose, it is necessary to control not only motion but also many modes of bending vibration. For the purpose, an extended reduced order physical model that is able to express simultaneously the motion and bending vibration of the flexible rotor taking into consideration of gyroscopic effect is proposed. Furthermore, a new controller combined PID with LQ control is adapted to control the flexible rotor. Effectiveness of the proposed modeling and control approach for the flexible rotor is verified through simulations and experiments.

View full abstract

In this paper, we examine an effective vibration control method for rotor-bearing system in an operation condition in which an oil whip occurs by using adjustable quasi-circular bearing with changeable configuration of cross section. This bearing can arbitrarily change the bearing clearance distribution in circumferential direction by using a piezoelectric actuator installed between bearing casing and metal. We confirmed from numerical studies that the threshold speed rose when the metal cross section was deformed the position of 30 to 40 degrees in the direction of shaft rotation from gravity from the metal center.

View full abstract

This paper presents the evaluation of first mode damping ratios, the changes along passages, and amplitude dependence for a middle-rise steel framed building based on measurement data. The building is 50 m height. It is rectangular plan and many data are simultaneously collected in two horizontal directions at optional points on the top floor. By using random decrement technique, first mode damping ratios are calculated. It is clarified characteristics of the changes along passages of first mode damping ratios based on microtremor measurement, and amplitude dependence based on strong wind and earthquake measurement.

View full abstract

The purpose of this work is to identify the characteristics of a nonlinear 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, exiperimental model analysis was executed for an asymmetrical nonlinear vibration system, and showed nonlinear mappinng.

View full abstract

The authors investigated the effect due to passengers on vertical elastic vibrations of railway vehicle carbody experimentally and analytically. Stationary vibration tests for an actual commuter vehicle on which up to 14 passengers aboard were carried out using a multiple input wheelset-excitation system. The commuter vehicle has a number of natural modes of elastic vibration in the high-sensitive frequency region of human, and two of them particularly affect the Frequency Response Function (FRF) of the carbody. It was apparent that the peak values of FRF, which correspond to those two natural modes reduced in a similar manner when the number of passenger increased. On the other hand, the changes of peak frequencies are very small. The effects due to passengers' posture and distribution are also studied. Moreover, we proposed an analytical model to express the three-dimensional elastic vibration of carbody and the effect due to the passengers, and verified the adaptability of the model by comparing the calculation results with the experimental results.

View full abstract

We developed an estimation method using the Bayesian approach to generate the probability distribution of the damping ratio from a vibration test with a small sample size. The Bayesian approach has special significance to engineering design, where available test data is invariably limited, for the approach can systematically incorporate subjective judgments based on experience or indirect information with observed data. We supposed that the probability distribution of the damping ratio has a normal distribution. Therefore, we applied the Bayesian approach to estimate unknown parameters of the distribution. In addition, we compared this method with a method of moments classified as a classical estimation and investigated the influence of sample size by conducting an evaluation test.

View full abstract

The method for measuring damping property generated by the movement of the granular material filled vibrating container was devised, and loss factors of several types of granular material were measured. Consequently, it was found that the loss factor tended to increase, as granular material filler content is less, as acceleration amplitude of the container is bigger without relating to the types of granular material within investigating.

View full abstract

Numerical modeling of damping effect of an impact damper with granular materials is essential for efficient design of structures set with dampers. In this paper, the method for experimentally evaluating damping effect is proposed. Then the damping effect is modeled as equivalent additional mass, equivalent non-linear spring force and equivalent non-linear viscous damping force. The validity of the methods is examined by comparison with experimental result.

View full abstract

Conventional linear viscous damper has the trade-off characteristics between vibration suppression effect of peak resonance amplitude and increase of vibration between resonance points. In this paper, the nonlinear dampers to solve such problems are proposed and investigated. Two kinds of nonlinear dampers, power series type and step function type, are proposed and set between mass points of two-degrees-of-freedom system. From theoretical results, it is clarified that some types of power series type nonlinear dampers and step function type nonlinear damper not only suppress the peak resonance amplitude but also avoid the increase of vibration between resonance points.

View full abstract

The conventional studies on the granular material impact dampers, rarely take the dependency of restitution coefficient on relative impact velocity due to elasto-plastic deformation at the impact into consideration. In this paper, elasto-plastic materials such as lead are treated. The elasto-plastic behavior at the impact is modeled as a bi-linear type force-displacement characteristics. Impact behaviors in the horizontal and vertical plane are evaluated by numerical simulations, and the viblation mitigation capability is investigated for various container configurations.

View full abstract

This study treats the elasto-plastic deformation and buckling behavior of thin cylindrical shell subjected to multi-directional excitations. A steel cylindrical pier is modeled as a thin cylindrical structure with an attached mass on its tip. Numerical simulations are carried out, where the horizontal and the vertical seismic loads are applied simultaneously. The effects of the horizontal and vertical input frequencies and input accelerations on the dynamic behaviors are studied, under both the elastic shell assumption and the elasto-plastic shell assumption. It is found that flattening phenomena will occur for the elastic shell and the buckling phenomena similar to that found in Hyogo Ken Nambu Earthquake occurs for the elasto-plastic shell.

View full abstract

An elevator rope for a high-rise building is excited forcibly by the displacement of the building caused by wind forces. In this paper, an approximate solution to the forced vibration of a rope where both ends are moving is presented; based on the assumption that the rope tension and movement velocity are constant, and that the damping coefficient of the rope is small. Finite difference analyses of rope vibration are also performed to verify the validity of this approximate solution. The calculated results of the finite difference analyses are in fairly good agreement with that of the approximate solution.

View full abstract

In this paper, the optimal seismic design methodology which can consider the structural integrity of both the piping systems and the elasto-plastic dampers are developed. This methodology employs genetic algorithm and can search the optimal conditions such as the supporting location and the capacity of the dampers. Four kinds of evaluation functions are considered. As the results, it is found that the optimal seismic design methodology proposed here is very effective and can be applied to the actual seismic designs for the piping systems supported by the elasto-plastic dampers, and can be also applied to the piping systems exposed to the actual earthquake waves which have various frequency components.

View full abstract

Japan is famous land of earthquake in the world. As for the nuclear power plant, high earthquake-resistant design is required. As a rule, the equipment and the piping system is assumed as rigid structure. In earthquake-resistant design phase, it is designed by using static design method. But, the earthquake is cyclic load. Therefore it is very important to grasp vibration. In this paper, forced vibration experiment and continuous vibration experiment are examined, and these results are evaluated from viewpoint of energy balance.

View full abstract

Generelly it is difficult to design control parameters in multiple inverted pendulum system. Because both inputs to stabilize a pendulum in inverted position and to swing up control another pendulum interfere each other. To solve the problem, we propose a swing up method of giving target position to cart and causing nonlinear sympathetic vibration. In addition, we apply the subspace control method to this model in oreder to design the control parameters easily. In this report, we denote the swing up method and verify the effectiveness by numerical simulation.

View full abstract

Swing up control of a serial double inverted pendulum system is an interesting problem because it is a nonlinear and underactuated mechanical system. Generally, each pendulum is swung up to upright position stepwise. But in a control process for stabilizing one pendulum and swinging up the other, two different control inputs interfere with each other. In this report, we propose a new control scheme to swing up a pendulum using resonance of nonlinear system. Also, we verify the effectiveness by numerical simulation.

View full abstract

One of the most serious problem we are facing is the number of estimated parameters is too big to be calculated by using a micro-computer. Moreover, genera feedforward adaptive control algorithm needs real-time system identification of the plant. In this study, we propose a simple method to attenuate only resonance peaks of vibration of cantilever beam based on MIT rule. The parameters to be estimated in real-time are only the amplitude and phase of a sinusoidal signal to cancel the vibration at resonant points of the beam. This simple algorithm never need previous system identification and reference signal as to be needed in general adaptive systems. Some experimental results show the efficiency of the algorithm.

View full abstract

Works with different friction coefficients can be separated by being transported to different directions when phase difference of elliptical vibration is controlled adequately. On condition that works are transported with jumping, metal's phase difference with zero velocity increases whereas plastic's phase difference with zero velocity hardly increases. This paper demonstrates that works can be separated at high velocities, widening the margin between works' phase differences with zero velocity. In the verification experiment using electronic parts whose face side is metallic and reverse side is plastic, many works can be separated by face/reverse side at short times.

View full abstract

A crane mounted on a tower-like flexible structure called the 'Tower crane' has a problem that a fast transfer of the load causes the sway of the load and the vibration of the flexible structure. We have already shown that it is possible to control both the sway and the vibration by the inherent capability of the tower crane. Although our control method assumed using a torque-control motor, the real tower crane uses a speed-control motor. This paper derives the control design model considering a speed-control motor by using block diagrams of the local feedback of angular velocity. We design the H_∞ controller and verifies its efficiency by experiments.

View full abstract

The improvement of current collection performance is necessary to increase commercial speed of Shinkansen. Therefore, contact force between a contact strip of a pantograph and contact wire should be constant. However, contact force fluctuates severely at high-speed domain due to vibration of contact wire and lift force. In this study, contact force control technique by using an air actuator and a PID controller would be discussed to reduce the contact force fluctuation. The control devices were built into a low-noise pantograph and some experiments were curried out by using the current collection testing equipment and the large-scale wind tunnel to validate ability of active control.

View full abstract

In recent year, railway vehicles are becoming lighter since it corresponds to improvement in the running speed. However, this affects a degree of ride comfort as increase in bending vibration due to the deterioration of the body rigidity. Recently, passive vibration suppression with piezoelectric elements which are shunted by electrical circuits is paid attention in order to control vibration of structure. This report shows the experimental results using 1/6-scale experimental setup attached stack type piezoelectric actuators. In the experiment, a serial connected inductor and resister circuit use as shunt circuit. Moreover, including the negative resistor in the circuit reduce the internal resistance of the inductor in order to tune the shunt circuit optimally.

View full abstract

In order to improve the riding comfort of railway vehicles, it becomes essential to suppress the vibration of the rigid mode of the carbody as well as the one of the vertical bending mode. Therefore, we propose a method to suppress these vibrations by using the damping force control systems of axle dampers and air springs; the first is applied for suppressing of the first mode bending vibration, the second is applied for suppressing of the rigid mode vibration. As the results, we show that the control method effectively reduces the power spectral density (PSD) of accelerations of the carbody floor.

View full abstract

A lightweight of carbody for high speed brings about fall of flexural rigidity. So vertical vibration of a lightweight high speed railway vehicle makes worse the ride comfort of passengers. This paper aims at reducing such vibration, especially the 1st mode bending vibration of carbody, with the active suspension system using the proposed method of designing an vibration control system. The controller was designed by applying the H-infinity control theory. The numerical simulation results show that the ride comfort of passengers are greatly improved by the active suspension.

View full abstract

This paper proposes a new rail vehicle concept of three axles one unit vehicle with self steering single axle. Usual single axle vehicle required the short & width car body as a system design of next generation railway vehicle. However, Authors propose a new Three Axis One Unit Vehicle with steering single axle truck for railway vehicle. This proposal use three trucks in a vehicle with normal body length of conventional train, and this method has a merit to decrease elastic body vibration with light weight car body by setting a truck in the middle of car body. This system design can expect high performance for stability, curving performance, and axle load limitation. The analyses with multi-body dynamics simulations were made and the basic characteristics were cleared. Finally, 1/10 scale model vehicle was made and the proposed vehicle has a potential for high performance is proved from running experiments including curving.

View full abstract

Recently, railway vehicle is extensively lightened since this lead to the speed-up. However, the simplification of car body shell structure and alternative light material causes the deterioration of the body rigidity, and leads to the increase in a vertical bending vibration of the car body. In addition, the deterioration of riding comfort concerns to this issue, because the natural frequency of the bending 1^<st> vibration overlaps with human's uncomfortable sensitive frequency band. Therefore, the objective of this research is to reduce bending 1^<st> vibration by embedding piezo-electric actuator in the actual lightweight railway vehicle car body.

View full abstract

A pulsed laser tracking/control system and a laser communication system using a MEMS (Micro-Electric-Mechanical-Systems) mirror for micro-vehicles are presented in this study. Micro-vehicles have been attracting the attention of aeronautics and astronautics engineers because they can be potentially useful for surveillance and monitoring applications. The two optical systems to conduct the laser communication for micro-vehicles achieve the miniaturization and lightening of vehicle communication systems effectively because laser has high directivity and it is possible to concentrate the power. First, an experiment with a miniature vehicle is carried out to verify the performance of the pulsed laser tracking/control system. Next, a fundamental experiment for laser communication system using a MEMS mirror is performed.

View full abstract

By processing triangle or square pyramid shaped indents on a flat sheet following regular plane tiling patterns, panels with periodical indents are manufactured. By setting this panel (as top panel) on reversed one (as bottom panel), and gluing them at the apexes of pyramids to nodal points of the tiling patterns of bottom panel, highly rigid core panels are newly developed. The basic model named "dia-core" corresponds to the space filling models by two tetrahedra and one octahedron. Besides, varying the geometric patterns which appear on their surfaces, various modified models are devised. This pattern variation is known as Archimedean plane tiling in geometry.

View full abstract

Vehicle interior noise can spoil passenger's comfortableness. Especially it is difficult to reduce low frequency noise such as booming noise. So the purpose of this research is to reduce vehicle interior booming noise using panel based resonator. Panel based resonator is composed of honeycomb core and perforated plate. Each cell of panel based resonator is made to specification according to the same resonant frequency of corresponding Helmholtz resonator. Resonant frequency varies with cross area of holes. Panel based resonator reduces noise most effectively when it is made to specification according to the frequency where SPL (sound pressure level) is the highest.

View full abstract

The characteristics of two new structures, namely (1) origami tube structure and (2) truss core panel are checked as a measure to protect pedestrians. Origami tube structure shows an alternative procedure of changing the origami structure to give it robustness of characteristics against the impact angle. Truss core panel is a rigid panel developed from the geometry on space filling. Honeycomb has a similar high stiffness performance. This is produced by adhesion or brazing, so it's weak against heat and very expensive. On the other hand, truss core panel can be made with metal and be welded, so it's strong against heat and usually cheap, which showed outstanding strength characteristics.

View full abstract

The "Origamic" approach gives us useful information and suggestion in the design of folding pattern of membrane, which can be applied to retractable membrane roof or foldable membrane structures. In the Origamic approach, membrane is assumed that it has perfect shear rigidity and its flexural deformation occurs only along the crease line. In the paper extraction of basic folding pattern from eigen modes of bending deformation is firstly proposed. Then the condition of foldability and its applications to the generation of foldable pattern in the finite displacement range are also proposed. Finally the patterns and conditions are examined by folding analysis.

View full abstract

This paper presents a self-sensing method for semi-active vibration suppression that measures only the value of piezoelectric voltage. The method separates electrical status into two cases concerning electrical current, and characterize each of these to establish a self-sensing system. Experiments revealed that the self-sensing system suppressed vibrations by combining the state-switching control or the synchronized-switching control. We confirmed that the self-sensing method is robust against model errors through the vibration suppression experiment subject to model errors caused by intentional frequency shift.

View full abstract

In the authors' previous report, a self-sensing actuator with laminated piezoelectric films was proposed, and the validty of the proposed method was shown by performing their vibration control experiment of a beam and a rectangular plate. However, the slight difference between circuit components such as piezoelectric capacitance and their variation with time and temparature made the closed-loop system unstable. Therefore, variable resistors needed to be fine-tuned manually so as to keep the bridge circuit balanced. However, this adjustment work was cumbersome and complicated in that it was needed to be done by trial and error. In this study, a distributed smart damper using four laminated piezoelectric films is developed by using an analog multiplier and a digital signal processor in order to provide the bridge circuit with self-tuning function. In the experiment, this smart damper is applied to a cantiliver beam. After operating the self-tuning function according to the least-mean-square algorithm, free vibration control of the first mode of a cantilever beam is performed with a convergent parameter. It is verified that enough control effect is actually obtained and this control effect is almost equal to the effect obtained in cases where the bridge circuit is tuned manualy.

View full abstract

This paper proposes new methods which improve the robustness and the performance of the passive vibration suppression using piezoelectric elements applying the dual-inductance circuit. Two types of methods which use two inductances were proposed in this paper. Because the electrical systems of new methods have two resonances, they could solve the problems of the performance and the robustness which had not been done by previous methods. Optimum values of the circuit were derived both with and without considering the variation of the stiffness of the main system. The effectiveness of new methods and the optimum values of the circuit were verified by calculation and experiment.

View full abstract

This paper presents a new design method for active acoustic isolation and acoustic vibration suppression of a target structure. Two key ideas are used in the new design. The first one is to estimate transmitted sound pressures by using generated voltages of piezoelectric elements on a smart board. The second one is to use different weighting functions in frequency domain for each evaluating points considering the dynamic characteristics of the target structure. The control system for smart board is designed by using mixed H2/H∞ control. The result of numerical simulation shows that the present method is effective in reducing acoustic vibration of the target structure and the performance is superior to the ordinary method.

View full abstract

We propose an electro-mechanical model for the ionic polymer-metal composites (IPMC) beam. The model is based on considerations from an electrochemical point of view and has nonlinearities in nature.

View full abstract

It was found that the bending curvature and generated force of largely dehydrated Selemion sandwiched between thin silver layers came to have a definite correlation to the quantity of charge given to it. Both curvature and force have almost linear relationship to the charge quantity. It was interpreted as the control of charge would result in the control of curvature and force, which are the essential characteristics for the actuator. In fact, we could observe the precise controllability of curvature and force of Selemion by the control of charge quantity given to Selemion.

View full abstract

This paper proposes the equivalent mechanical model and the equivalent electrical model for models of vibration suppression methods in flexible structures using piezoelectric elements. There are two main methods to suppress vibration of flexible structures. One is active vibration control and the other is passive vibration suppression. Because both of them include both mechanical and electrical system, the mechanism of the vibration suppression becomes complicated and can not be understood easily. To make matters worse, knowledge of the mechanical vibration suppression device and the electrical circuit are not utilized in those models using piezoelectric elements. Hence, this paper describes the way to derive the equivalent mechanical and electrical models and the effectiveness was investigated by quoting some vibration suppression methods.

View full abstract

By the standard, the discrimination of golf club can not be attempted concerning the flight-distance today. Then, the movement which intends to raise added value of golf club in feeling merit of the hitting sound is noticed. In this study, we made hitting sound prediction program for the purpose of predicting the hitting sound by design stage for attempting cost reduction in product development. In this paper, we describe the result of the practicability of the program which using hollow cylinder material equal to the driver.

View full abstract