In Tanegashima, sugarcane cultivation and sugar manufacturing are main industry. The sugarcane bagasse from sugar manufacturing process is burned in bagasse boiler and supply heat and electricity demand in the sugar mill. The bagasse boiler exhaust unused heat about 200 °C during milling period due to combustion of excess sugarcane bagasse. In the island, there are some factories such as food processing factories consuming imported heavy oil to generate around 120 °C pressurized steam through a year for their processes. Thermochemical energy storage and transport system utilizing zeolite steam adsorption and desorption cycle can resolve this spatial and seasonal heat mismatch. The “Zeolite Boiler”, which can generate 0.2 MPa/120 °C steam continuously by employing moving bed and indirect heat exchanging process, requires adsorption steam generated by an existing boiler to release stored energy of zeolite. Thus, reduction of steam consumption from the existing boiler is essential to increase in revenue. Food processing factories use steam for their indirect drying process and exhaust high-temperature/humidity air which can be introduced into the Zeolite Boiler replacing boiler steam. A bench-scale Zeolite Boiler with 10 kg/h of mass flow rate of zeolite demonstrated the increase in heat increasing rate by introducing high-temperature/humidity air. A numerical model validated experimentally predicted the performance of a full-scale Zeolite Boiler and showed increase in fuel reduction rate by 32% point comparing the normal Zeolite Boiler without high-temperature/humidity air. While introducing high-temperature/humidity air increases fuel reduction, pressure drop in packed bed is expected to increase and increases corresponding power consumption of blower. By introducing RH=40% air into the Zeolite boiler, the revenue from fuel reduction is expected to overcome increase in electricity cost of blower.

Palm acid oil (PAO)-diesel mixed fuel produces NO_x: 10-30% lower than diesel fuel in an industrial diffusion burner without decreasing furnace outlet temperature remarkably. The main component of NO_x is thermal NO in this study. The NO produced in the furnace may be reduced before it emits out of the furnace. This study investigates NO reduction by PAO using a flow reactor. The results show that NO is difficult to reduce at stoichiometric mixture ratio, however it is likely to reduce at fuel rich condition with oxygen. At equivalence ratio 2.63, NO_x reduction ratio reaches 60% in diesel and 80% in the PAO contained fuel. At this time, the PAO contained fuels produce less thermally decomposed light hydrocarbons than diesel and yield more carbon dioxide, revealing NO and oxygen are easy to react with the thermally decomposed hydrocarbons or another radical produced with them.

Since the Great East Japan Earthquake occurred, it has attracted attention that power generation systems using waste biomass could be a feasible option to replace fossil fuels. The system can convert waste biomass such as garbage, paper, wood and so on into energy. Hence, it increases energy independence ratio in residential area. Since biomass has the characteristic of carbon neutral, the system can reduce CO2 emissions. However, conditions of waste biomass are different for their properties, so it is difficult to use as a fuel for power generation. Here, superheated steam gasification system is an effective energy conversion system, because it can handle wide range of waste biomass. When the syngas generated by gasification is applied to a gas engine CHP, high combined efficiency can be obtained. However, when analyzing superheated gasification power generation system using waste biomass, it was unclear how to operate the system due to the fact that the demand was not taken into consideration. Therefore, we constructed a platform for Superheated Gasification Power Generation System using Waste Biomass independent on the region and achieved user application.

Direct injection engine has high thermal efficiency, but the emission problems caused by fuel adhere on the combustion chamber wall surface have been pointed out. From this point, previous researches have confirmed the combustion characteristics improvement under the heterogeneous combustion field by using impinging injection. It has been proved that impinging injection could reduce the unburned components by the effect of spray collision. Therefore, in this study, experiments have been carried out to examine the effects of fuel properties and injection timing on fuel atomization and combustion improvement while using impinging injection and new developing multi-impinging fuel injection under the heterogeneous combustion field. The main conclusions are as follow: 1) While using impinging injection, there is a remarkable difference in SMD depending on the fuel properties even at the same injection pressure. 2) The optimum injection timing conditions exist for the combustion improvement effect of different fuels when using multi-impinging injection.

The aim of this study is to establish the CO₂ capture system from a gas-engine exhaust using a gas-separation membrane. At first, we investigated the effect of humidity in an exhaust gas on the CO₂ separation performance using a model exhaust-gas. As a result, it was found that the lower the relative humidity and absolute humidity, the higher CO₂ capture rate is. Furthermore, gas-separation tests were conducted using an actual engine exhaust. The almost same performances were obtained with an exhaust gas as model one. However, it is found that the specific CO₂ capture energy, which is about 5 [GJ/t- CO₂], is necessary to be reduced further to realize the significant reduction of the net CO₂ emission from engine system.

PM from hydrocarbon fuel combustion is problem for environment and human health. The mechanism of PM formation is the pyrolysis of fuel and its partial oxidation. In this study, pyrolysis of benzene as aromatic structure and dodecane as paraffin structure were investigated. Benzene and dodecane were heated using a flow reactor (1050 K to 1350 K). PM and PAHs were measured a glass-fiber filter and a Gas Chromatography. As the result, in the pyrolysis of benzene, various PAHs from lower ring to higher ring such as naphthalene of 2-ring to pyrene of 4-ring were detected.

Nanometer size Particulate Matter (PM) exhausted from internal combustion engine is one of the major air pollutants, and its reduction technologies are required. In this study, in order to clarify characteristics of PM formed through flame quenching process, a laminar diffusion flame of cyclohexane was quenched using slide and rotary metal mesh system. Mass concentrations of PM deposited on the metal mesh (Deposit-PM) and PM passed through the metal mesh (Through-PM) were measured when quenching at various positions in the flame. As the result, the mass concentrations of Deposit-PM and Through-PM resulted in maximum at the midstream part in the cyclohexane flame. In addition, oxidation behavior of PM was measured by a Thermo Gravimetric Analyzer. As the result, it was considered that the oxidation temperature of PM at upstream part in the flame was lower than that of PM at midstream part and downstream part in the flame. The activation energy of PM was estimated from the thermogravimetric analysis results. It was shown that the activation energy of PM formed by quenching of the cyclohexane flame was approximately 80 to 160 kJ/mol.

In order to understand PM emission by fuel firm combustion, we developed time resolved measurement method of PM exhausted from unsteady diffusion combustion of iso-octane fuel. In this study, soot formation from unsteady pool flames on a shallow dish under various ambient temperature conditions (room temperature – 700℃) was investigated as a fundamental study of fuel film combustion. Relationships among flame length, fuel consumption rate and PM exhausted rate were measured. As the result, it was found that the flame gradually increased with time elapsed and PM exhaust rate tended to be proportional to the fuel reduction rate and flame length. Therefore, it was also founded that total mass of PM exhaust during flame formation increased with ambient temperature raise.

In this study, exhaust gas components emitted from spark ignition (SI) engine were analyzed by using a comprehensive two-dimensional gas chromatograph (GC×GC) with a time-of-flight mass spectrometer (TOFMS). 1-hexene were used as fuels. The existence of hydrocarbons with nitro groups were suggested.

Small electronic devices such as mobile batteries need to be used for a long time and be lighter. The research goal is the development of an environmentally friendly micro hydrogen rotary engine (0.126cc HRE). This engine cannot operate independently. In order to clarify the factors, hydrogen combustion is visualized in RE and a combustion chamber simulating RE. White smoke was used for visualization. The experiment was conducted by supplying a mixture of air and hydrogen mixed with white smoke to the actual machine and the visualization simulated combustion chamber. As a result of the experiment, the movement of the flame kernel and the hydrogen combustion were visualized by the movement of white smoke in the visualization simulated combustion chamber. Visualization of hydrogen combustion was also possible with visualization 0.126cc HRE. It was found that hydrogen combustion can be visualized by using white smoke.

Combustion variation exists as one of the problems for improving the thermal efficiency of spark ignition engines. If the mechanism of combustion variation is clarified, effective control can be performed and it is expected to achieve higher thermal efficiency. this study aimed to elucidate the mechanism of combustion variation by constructing an IMEP prediction model for each cycle using the RF method which is a readable neural network. To evaluate the validity of the model, the model performance was verified by changing analysis target to a data set with no physical meaning, the physical equation with known the relationships, and the engine combustion data. Using the model, it is shown showed the factors that affect the cycle-by-cycle variation and the relationship between the factors, and it is clarified that the engine combustion may be influenced by the residual gas two cycles before, and is affected by intake and exhaust gas.

Diesel engines are widely used. However, they have issues of large emissions of nitrogen oxide and soot and high combustion noise. In order to improve understanding of the relationship between combustion noise and exhaust emission under various combustion conditions, this study investigates the effects of combustion impact on radiated combustion noise and exhaust emission characteristics for a single-cylinder diesel engine with a supercharger and EGR system by changing the fuel injection conditions, intake air pressure and oxygen concentration in the intake air. The results show that the engine noise greatly depends on the maximum combustion impact energy at 2500 Hz. As the maximum combustion impact energy is increased, NOx emission roughly increases, smoke emission roughly decreases, and CO emission roughly stays constant. However, there are some operating parameters which show different dependencies.

In this paper, the effects of inter-cycle interference, which are considered to be unique to the closed cycle, on combustion and the factors causing rapid combustion, which are unique to hydrogen combustion, are studied in detail by analyzing the pressure in the cylinder for successive cycles. In this study, based on the results of the after condenser gas temperature and pressure in the third report, the incidence of abnormal combustion was evaluated in each cycle at 25℃ and 40℃ after condenser gas temperatures, which is considered to affect abnormal combustion. For the evaluation of each cycle, the measurement and calculation accuracy were revalidated.

Near the future, environmental regulations for automobiles are being tightened toward zero CO₂. This engine has no exhaust, it is expected to be useful power sources in the future. The working gas can be freely selected due to the characteristics of the non-exhaust engine. In this study, argon was used because of its high efficiency. In the previous report, it was found that the cooling loss due to the characteristics of hydrogen combustion and the high temperature by the application of argon are issued for improving efficiency. In this report, to further improve the efficiency, a more detailed combustion analysis was conducted for the period that is dominant in cooling loss, the useful index of cooling loss was confirmed, and the cooling loss was evaluated.

Many researches concerning about energy crises and pollution problems have been done to use alternative fuels for fossil fuels and to lower the toxic components in the combustion products. We start to develop the hydrogen rotary engine as a new environmental-friendly small size power source. In the combustion chamber of the rotary engine, the air-fuel mixture does not diffuse into the combustion chamber due to the generation of squish flow, and the output decreases. For this reason, in this study, the diffusion of the air-fuel mixture was promoted by changing the fuel injection timing to promote combustion. As a result, the output was improved by 0.17 kW from the previous level. In addition, the improved output increased thermal efficiency by 3.6 %.

Used to reduce friction and wear between two solids such as lubricating oil and metal, and to prevent seizure. Lubricants require many functions. Various additives are added to meet those requirements. Among the additives, those added for the purpose of preventing direct friction by chemically reacting on the friction surface under extreme pressure conditions are called extreme pressure agents. phosphoric ester is a typical extreme pressure agent. Phosphate ester forms a film by adsorbing on the surface of metal and causing a chemical reaction. It is believed that this coating protects the metal surface. The authors systematically compare and evaluate the friction and wear characteristics of phosphate esters with different molecular structures. The authors have been elucidating the causes of physical adsorption by classical molecular dynamics analysis. In this study, we analyze the adsorption process by observing the amount of charge transfer and the amount of compound transfer using the reaction force field including the recombination of chemical bonds for the analysis of the mechanism of chemisorption and reaction. For the movement amount, a mean square displacement, which is a mean square of the start point and the end point of the movement, is used. As a simulation model, a phosphate ester alone and an iron substrate are arranged to compare the surface behavior of iron oxide and iron. As phosphoric esters, mono-oleylphosphate and di-oleylphosphate having different numbers of alkyl chains are targeted. As a result of the analysis, it was confirmed that the mean square change was constant. It is considered that it became constant by the adsorption. In addition, it was confirmed that the charge moved between the molecule and the substrate. It is considered that the charge was moved by the chemisorption. The charge transfer was found to be greater for di-oleylphosphate than for mono-oleylphosphate. This is probably because di-oleylphosphate has a larger number of charge-transferring atoms. Since the charge moves after the mean-square displacement becomes constant, it can be interpreted that the chemical adsorption is performed after the physical adsorption. The same process was observed for iron oxide.

It is required to reduce both the friction and lubricant oil consumption (LOC) in order to reduce CO₂ in internal combustion engines. In addition, as the requirement to reduce particulate number (PN) may be realized by reducing LOC, the relationship between LOC and PN should be examined. Elucidation of the mechanism of LOC belongs to a basic and applied field and a common subject, however, only the LOC is measured by the weight method in steady conditions and the mechanism is not clarified so far. Thereby, the relationship between LOC and PN was measured in a wide operation area including transient conditions using a production engine in this study.

In this study, tribological properties of fullerene suspended oil were investigated using a face-to-face contact-type testing apparatus. The specimens were aluminum alloy (A5056) disk and chromium alloy steel (SUJ2) ball having flat contacting surface. The lubricant was poly-alphaolefin (PAO) having various fullerene content. As a result, Fullerene suspended oil reduces friction. In addition, adhesion of the aluminum alloy reduced on ball surface. This is due to fullerene suspended oil formed lubrication film on aluminum alloy. But the friction was not reduced by the fullerene suspended oil in anodized surface. The case was the same with shot peened and roller burnished surface. These are attributed to fullerene sticked to aluminum alloy.

Three-dimensional multi-layered structure metal coating with different hardness distribution were developed as surface modification for the sliding interface of bronze. Zinc (Zn) was mechanically coated in segment structure, then tin (Sn) was coated over the entire surface. Heat treatment was conducted to enhance solid solution and intermetallic compound of Cu-SN-Zn system resulting in hardness distribution. The tribological properties evaluated with 3 ball on disc type testing apparatus in lubricated condition. The friction coefficient of the multilayered coating decreased rapidly from an initial stage of the experiment The friction coefficient after steady state was approximately 0.004. An interrupted observation of the disc surface suggested that transfer to the mating face was suppressed.

In this study, rolling contact fatigue of a trust roller bearing consisting silicon nitride ball as rolling element and zic coated raceway was evaluated. A wet and a dry process were applied to the zinc coating: A shot peening was used for the later process and the coating surface was relatively rough. A significant increase of the rolling contact fatigue life determined from flaking was found in the wet zinc coated surface. The fatigue life of the dry coated zinc raceway also increased. It was found that residual stress was applied by the zinc peening and raceway profile became smoother after the experiment. The oxidation of the zinc coated raceway degraded. It was suggested that the restriction of the raceway oxidation resulting in the increase in the rolling contact fatigue life.

Recently, the downsizing turbo is widespreading to satisfy the emission regulations of automobiles. It is necessary to develop the model to predict the mechanical loss in a turbocharger in the model-based development. In our previous research, a mathematical model with the mechanical loss caused by the bearings used in a turbocharger was developed. In the previous model, the friction loss is estimated by lubricant temperature, lubricant flow, thrust force and rotation of the turbocharger. The lubricant temperature applied in the previous model was the average temperature of the inlet and the outlet. However, the inner lubricant temperature is higher than the outer lubricant temperature in the journal bearing, then it is inappropriate to apply the average temperature. This research aimed to improve the accuracy of the previous model adding the prediction model of the lubricant temperature distribution in the journal bearing. We estimated the lubricant temperature distribution in the journal bearing by calculating the Reynolds equation and energy equation iteratively. The result revealed that the lubricant temperature distribution in the axis direction, and the predicted value came closer to the measured value than the previous model in case the supply lubricant temperature is low.

In this study, we investigate the flow rate through a narrow gap with a texture on the channel surface and how the flow rate through the gap changes compared to the flow rate without a texture. We have developed an experimental apparatus that allows us to adjust the thickness of the gaps, and we have conducted experiments using samples with different sizes, locations and shapes of textures on the channel walls. As a result, the flow rate decreases as the hole depth ratio increases, but increases in a region with a small depth ratio. The flow rate decreases as the total number of holes increases. The higher the Reynolds number, the more effectively the flow rate is reduced. In the case of only one hole, the flow rate decreases with a lower Reynolds number.

The floating bush bearing has a floating bush inserted between the bearing and the rotating shaft. Because of this，this bearing during bush rotation is one of the greatest concerns. In this study, the oil film was observed in a region where the shaft rotation speed was relatively low and the bush rotation speed tended to increase using X-ray computed tomography. This visualization method has the advantage that the oil film can be observed regardless of the bearing structure by CT images. From the acquired CT images, it was revealed that the oil film area in the inner clearance shrinks in the circumferential direction as the rotation speed increases. This phenomenon was caused by the fact that the lubricating oil in the outer clearance is supplied to the inner clearance by the oil film pressure due to the wedge action.

Self-excited vibration called the combustion vibration occurs in the combustion apparatus. The purpose of our research is to analyze the mechanism of generating the combustion vibration using a cellular automaton method (abbrev.CA). The expansion of the air in the heat source expressed by the vibration of the piston. Since the expansion depend on the flow velocity, the particle velocity in the heat source was fed back to the amount of vibration of the piston. Furthermore, we created a model when there is no convection. As a result, it was found that the particle velocity including time-delay causes self-excited vibration. Furthermore, the backward flow and the temperature drop of the heat source suppress the self-excitation vibration. Moreover, we were able to reproduce the experimental result of horizontal Rijke tube. It was also found that positive feedback of sound pressure promotes growth of self-excited vibration, and negative feedback suppresses growth of self-excited vibration.

In this research, the idea of the feedback path with delay time is applied to the flute sounding mechanism. When the exhalation jet hits the edge of the flute mouthpiece, the exhalation is divided into two parts at the edge and distributed inside and outside the tube. The mouth is at the open end, and at resonance frequency the particle velocity at the mouth opening is maximal and its direction is approximately perpendicular to the expiratory jet. Therefore, the trajectory of the expiratory jet fluctuates by the distance obtained by multiplying the elapsed time passing through the mouthpiece by the particle velocity, and the amount of exhaled breath distributed into the pipe is a function of time. And the cellular automaton method (hereinafter referred to as CA method) was investigated. The feedback of particle velocity data with delay time to the piston excitation velocity was equivalent to negative damping, and the acoustic particle velocity oscillated divergently.

As the self-excited phenomenon of the acoustic pipe system, the self-excited sound of the Rijke tube, combustion vibration, thermoacoustic phenomenon, and musical sound of a leadless wind instrument such as a flute are known. These systems include a self-exciting mechanism and oscillate at the resonance frequency of the acoustic system to generate a loud sound. For these systems, research on the self-excited mechanism is being carried out for each subject. However, since heat and fluid are involved, a clear self-excited mechanism cannot be explained from the viewpoint of mechanical dynamics. In this study, firstly the wave equation of an acoustic pipe excited by a point is derived. Secondly, it is replaced with a vibration system with one degree of freedom by using modal analysis. Then, the self-excitation mechanism is investigated by positively feeding back the state quantities (particle velocity and sound pressure) of the acoustic system to the input of point excitation. As a result, positive feedback of particle velocity is equivalent to proportional control (P control) that assumes displacement output in a 1-DOF vibration system. And positive feedback of sound pressure is equivalent to the differentiated control (D control) that assumes displacement output in a 1-DOF vibration system. It is shown that the feedback path with delay time element causes negative damping and self-excited oscillation. It is also shown that the result of this calculation using modal analysis is completely in agreement with the result calculated by the cellular automaton method (CA method) which describes the solution of D'Alembert in the wave equation.

Acoustic impedance of a rectangular orifice of a resonator on a side wall of a duct was measured. The measurement was based on two-microphone-method, in which the acoustic impedance was calculated from the transfer function of sound pressures at the end of the resonator and at the outlet of the orifice. The acoustic impedance, especially the resistance θ_p at resonance frequency f_p, depends on the particle velocity mach number undulating through the orifice M₀ and the flow speed mach number in the duct grazing over the orifice M. When the grazing flow speed mach number M is small, the resistance θ_p mainly increases with the particle velocity mach number M₀. On the other hand, when M is large, θ_p increases with M and is almost independent of M₀. In the latter state, the sound pressure at the resonator end decreases with M while the sound pressure at the orifice slightly increases with M, which results in the increase in θ_p. Those two states are roughly classified by use of the ratio M/M₀; M/M₀ is lower or higher than around 3.

A vibration reduction method that involves installing two flexible joints in series has been found to be useful for countermeasures against structure-borne sound in pump piping system. This technique is very useful compared to the general noise reduction which installs many vibration isolators in the whole system. However, the effect of reducing sound propagation in piping has not been completely explained yet. In this study, the simple apparatus having the straight-line piping is treated, and the reduction of sound propagation in piping by installing flexible joints is verified analytically. The numerical analysis results confirm that sound propagation in piping is reduced by the difference in sound velocity between the pipe and joint, and the change in acoustic energy. Furthermore, it was confirmed that the length of the joint and between joints is important reducing sound propagation in piping.

The self-sustained oscillations in a cavity flow with acoustic radiation are controlled by an intermittently driven plasma actuator, which induces spanwise non-uniformity of the incoming boundary layer. To evaluate the control effects, compressible flow simulations have been conducted along with wind tunnel experiments. The feedback control by driving the plasma actuator only in the time of intense sound pressure level in the cavity was performed. As a result, the sound reduction level of 11 dB was achieved, where the plasma actuator was approximately periodically switched-on and switched-off at the intermittent frequency of 50 – 100 Hz. Moreover, the influence of the intermittent frequency on the sound reduction was investigated for the control with a temporally constant intermittent frequency. It was presented that the largest reduction level of 13 dB was achieved by the control with the intermittent frequency of f_i = 200 Hz. To clarify the mechanism for this influence of the intermittent frequency on the control effects, the time variation of the incoming boundary layer and cavity flow during the intermittent period was investigated. The maximum non-uniformity of the incoming boundary layer during the control was larger for the effective control with f_i = 200 Hz compared with the control with higher intermittent frequencies. In the cavity flow controlled with f_i = 200 Hz, the vortices causing the cavity tone was constantly suppressed during the intermittent period. Meanwhile, for the case with the lower intermittent frequency of f_i = 50 Hz, weakening and reinforcing of the vortices were repeated in the intermittent period.

We conducted wind tunnel experiments to investigate the effects of an H-type Darrieus wind turbine arm’s cross-sectional shape on the turbine’s power performance and aeroacoustic noise. In particular, we focused on the effects of the width, leading edge shape and trailing edge shape of the arm’s cross-section. The results showed that narrowing the width of the elliptical arms increased the power output and overall A-weighted sound pressure level (OASPL). The cases of rectangular leading-edge arms showed lower power output and OASPL than the cases of arms with the trailing-edge shape of an airfoil’s leading-edge. The cases of rectangular trailing-edge arms showed lower sound pressure level (SPL) due to suppressed Aeolian tone in the low frequency range and increased SPL over a wide high-frequency range as compared to the cases of arms with the trailing-edge shape of an airfoil’s leading edge.

This paper describes the details of compact wind tunnel with lower noise to investigate the aerodynamic noise generation mechanism. Recent years, high speed running machines, for example bullet train, aircraft, etc., generate the sound which is called wind noise caused by the air flows. This noise makes us uncomfortable and causes a lot of environmental problems. However, few researchers have established a way to reduce the sound. Therefore, the compact wind tunnel would be made. The sound is able to be measured by the wind tunnel. By measuring the sound and the flow velocity around a measuring object, it can find out the correlation between air flows and noise generation, which enables the discussion of noise generation mechanism.

As noise of automotive, there are the noise of engine, the noise of power train, the noise of intake and exhaust systems, tire/road noise, and so on. In recent years, the number of hybrid vehicles and electric vehicles which the noise of engine, power train and intake and exhaust system is small is increased. As a result, the contribution of tire/road noise becomes relatively large in the noise of automotive. The source of tire/road noise is such as Pattern groove resonance sound, excitation sound due to uneven road surface. It is considered to noise in the low frequency band caused by tire vibration from road surface input are influenced by vibration characteristics of tires. For that reason, it is important to predict tire vibration during rolling and vibration characteristics of tires. In this study, sound characteristics of automotive tire were investigated by rolling experiments. Using two types of automotive tire and sound characteristics of tire/road noise were compared.

Air entrainment of a water discharge from a link-sleeve valve (LSV) was investigated with its application to the dam outlet works in mind. For large head discharge in order to prevent cavitation erosion, vibration, and noise, air must be injected into the downstream pipe to recover the pressure. However, the appropriate rate of air injection is certain only for the jet flow gate valves (JFG) now widely in use. We investigated experimentally the air suction characteristics of an LSV and found that there is a close analogy with a jet pump or an ejector. Present findings could be useful for improving the potential use of LSV as a more low-maintenance alternative to the JFG.

In many fluid-structure interaction problems, the “added mass” and viscous damping force are important interests. In this study, the added mass force and the viscous damping force are considered as the fluid forces acting on an oscillating object, and the authors focus on the fluid forces acting on an oscillating sphere in stationary incompressible-and-viscous fluid. Experiments were conducted to specify the fluid force coefficients for various diameters of oscillating spheres with finite amplitudes. The oscillation of the sphere was realized with a pendulum. The authors compared the experimental results with analytical values by linear theory under the assumption of infinitesimal amplitude. This comparison found that the experimental results contain additional forces come from fluid forces acting on a suspending wire of a pendulum. Therefore, the experimental results were corrected using the computation of fluid forces exerted on the wires. As a result, the corrected experimental results showed good agreement with the linear theory at infinitesimal amplitude. Fitted curves for fluid force coefficients as a function of a non-dimensional amplitude parameter KC were obtained in which the on linearity of viscous damping force was confirmed. In addition, a relation between the fluid forces and Reynolds number was discussed.

This paper presents an analysis and experiments on the self-excited vibration of a floating plate and a support structure. In this study, the analysis model and the experimental apparatus have elastic support structures and multi air supply holes. The vibration characteristics and the unstable conditions of the self-excited vibration are examined through the analysis and the experiment. As a result, the vibration characteristics and the unstable conditions are clarified. Especially, it is shown that in-phase mode and anti-phase mode vibration occurs when the large spring constant and the large number of air supply holes. Moreover, theoretical results are compared with experimental results, and the difference is discussed. Lastly, effect of the damping elements is examined through the analysis.

This paper presents flutter characteristics and measurements of exciting fluid force of multi-articulated flat plates. In paper printing or film manufacturing process, sheets are transported at a high speed and dried by air blow. In these steps, flutter may occur on the sheet due to air flow. This flutter leads to sheet breakage and reduction of productivity. It is necessary to clarify flutter characteristics and occurrence conductions. In this study, pressure fluctuation of a vibrating multi-articulated flat plate is examined experimentally by using an articulated flat plate which can measure the surface pressure instead of sheets. By calculating the energy balance from the pressure fluctuation, it is compared with the result of the analytical solution.

Presently, there are many patients who lost their voice caused by layngectomy, laryngeal injury and so on. The voice is very important communication method for human, and when the voice was lost, the patients often causes the mental distress. For these patients, the research about speech production substitutes are implemented. However, they have problems with regard of voice quality, articulation and intonation. For example, the electrolarynx has good features of voice continuity, sound volume and acquisition. However, it has poor voice articulation because of its uncontrollable pitch frequency. Our research aims to realize the electrolarynx with high-level controllability. We focused on using the myoelectric signal of sternohyoid muscle (SH) to control the electrolarynx. The SH has the function of vocal cords relaxation and activate during the utterance of low-tone voice. Therefore, the pitch frequency of electrolarynx can be controlled using the myoelectric signal of SH. In this report, we performed an experiment for the controllability evaluation using the control signal obtained from the myoelectric potential signal in order to control the pitch frequency of the electric larynx in two steps, high and low. The experimental result was compared from the result of three steps (high, middle and low) control, and it was confirmed that this method had the high control accuracy.

So far, the method to quantitatively evaluate the load applied to the lumbar intervertebral disc using the body surface shape of the waist has been proposed. This report clarifies effects of pelvis on lumbar disc load. Therefore, we investigate the relationship between pelvic angle and load ratio in forward/backward pelvic tilt, upper body bending motion, and static forward tilt posture. These experiments are conducted in standing and sitting postures. As results, it was confirmed that the load ratio was decreased due to the pelvic tilt and that the effect of pelvis was greater in sitting posture. Additionally, the load ratio increased with increase of the forward tilt angle in standing posture, but the load ratio fluctuation was not so much seen in sitting posture. This is considered to be because the load compensation due to the pelvic tilt in sitting posture is large. From these, it was found that forward tilt of pelvis plays a role in compensating for lumbar disc load and that it has a greater effect in sitting posture. Thus, it became possible to divide the load ratio into the effects of upper body flexion and pelvic tilt, and it became possible to examine the relationship between posture and lumber load in more detail.

The wearable power assist device that assists the knee extension torque generally has a fixed rotation center, which causes a slippage from the viewpoint of the anatomical structure of the body and multiple degrees of freedom. In order to improve it, a brace has been developed in which the rotation center moves with flexion. In this study, the amount of slippage working of these two types of knee brace was estimated by simulation and compared. There are two slippages. The angular gap between the normal knee and the knee brace. The axial slippage of the normal shank. As a result, it was found that the slippage of the rotating center knee brace was smaller, which is considered to be similar to that of a normal knee joint. In addition, when the joint moment was calculated including the effect of slippage, the maximum difference was 11.6% better for the rotational center knee brace. From these things, it is considered that the moving rotational center knee brace is more useful than the fixed rotational center knee brace.

Japan is a super-aging society, with an average lifespan of 80.98 years for men and 87.14 years for women in 2016. However, the healthy lifespan is 72.14 years for men and 74.79 years for women. The difference between the average lifespan and the healthy lifespan is a problem. One of the causes of this problem is the decline in physical function with age. Therefore, it is necessary to prevent and cope with age-related muscle weakness and locomotive syndromes. The loss of physical function with age is similar to the loss of physical function experienced by astronauts living in space for a long time. It is thought that conducting research in a microgravity environment can solve the problem. Therefore, in the context of the development of rehabilitation methods and devices, Influence of partial gravity environments such as the Moon and Mars, where human exploration is planned, on human walking was investigated. Walking in a partial gravity environment was simulated by regulation of body weight relief by using an anti-gravity treadmill, and the walking motion was measured using a wearable motion measurement device and recording electromyogram (EMG).

As a result, from the changes observed in ground reactions forces and joint angles, it was found out that the gait becomes floating and gets closer to a slow tiptoe walking patterns were noted in response to body weight reduction using the anti-gravity treadmill. Furthermore, the changes in EMG patterns indicated that physical burden is reduced.

Our research group is developing a simple method for estimating the floor reaction force by using inertial sensors. Until now, the number of sensors was reduced from 15 that is installed in all the divisional parts of the whole body to selected 7 by examining them in the time domain, thus reducing the burden on the user. However, the estimation accuracy decreased. In this paper, the floor reaction force was estimated using a single sensor by using the estimation method of unmeasured part acceleration as shown in the previous paper. The method is to estimate the unmeasured part acceleration in the frequency domain using the motion mode function, then obtain the acceleration data in the time domain by inverse Fourier analysis. The motion mode function is obtained by dividing the result of the Fourier analysis of the unmeasured part by the result of the Fourier analysis of the measured part for each frequency component. This time, the acceleration of the four extremities, head, and lower trunk of the unmeasured part is estimated with the upper trunk as the measured part. The estimation accuracy was verified by a correlation coefficient comparing the floor reaction force derived using these accelerations with the floor reaction force derived using the accelerations obtained from 15 sensors and the measured values of the floor reaction force. The results show that the floor reaction force derived from the estimation method of unmeasured part acceleration are similar to those derived from 15 sensors, demonstrating the usefulness of the floor reaction force estimation method based on frequency analysis.