Although bladed disks are nominally designed to be cyclically symmetric (tuned system), the vibration characteristics of all blades on a disk are slightly different due to the manufacturing tolerance, deviations in the material properties, and wear during operation. These small variations break the cyclic symmetry and split the eigenvalue pairs. Bladed disks with small variations are referred to as a mistuned system. Many researchers suggest that while mistuning has an undesirable effect on the forced response, it has a beneficial (stabilizing) effect on blade flutter (the self-excited vibration). Therefore, it is necessary to optimize a bladed disk for forced vibration and blade flutter. In this study, a practical optimization method of bladed disks that makes resonant stress and amount of unbalance of the bladed disk minimum by sorting the blades on a disk while keeping the stability for blade flutter. To verify the proposed optimization method, first, the original mistuned bladed disk, which has the maximum amplification factor, is generated by Monte Carlo simulations. Second, the optimal bladed disk with the minimum amplification factor and the minimum amount of unbalance is searched by using Monte Carlo simulations and the genetic algorithm. To keep the stability for blade flutter, alternate mistuning is applied. From the analysis results, the validity of the proposed optimization method is verified.

Automatic autorotation landing system for helicopters that is applicable under various flight conditions is proposed. This system consists of a control system that stabilizes rotational speed of the main rotor and reduces the descent speed before landing, and the ground altitude calculation algorithm to obtain reliable data. The control system is designed and validated based on the comprehensive helicopter dynamics model with an induced velocity model which is newly developed for descent at low speed. A rotational speed controller stabilizes main rotor speed during dive and is switched to descent speed / thrust controllers which reduce descent speed during flare. Velocity reference trajectories are adjusted based on control simulation results and empirical philosophy by a skilled flyer. The ground altitude calculation algorithm combines a barometer and a LiDAR to eliminate invalid data at both high and low altitude. By conducting flight tests in the actual environment, autorotation dive, flare and soft landing are successfully achieved without any aircraft damages. Comparing experimental and simulation results, the accuracy of the developed model at low speed descent is validated. In addition, results of flight envelope calculations suggest capabilities of the proposed system for various initial flight conditions.

In this paper, vibrational frequency effect in dynamic coefficients of tilting pad journal bearing is verified experimentally. Tilting pad journal bearings (TPJB) is applied in various turbomachinery. Accurate evaluation of the bearing characteristics of TPJB is very important to ensure reliability of rotating machinery. To evaluate the stability of such rotating machinery for sub-synchronous vibration accurately, examination of damped vibrational frequency effects in dynamic coefficients of TPJB under various bearing load condition is necessary. In this study, excitation test with test rig of 4pad TPJB with two types of preload or pad offset ratio is carried out in various load condition. Especially, the test condition where the influence of fluid inertia is small is focused. Frequency effect in dynamic coefficients of TPJB is verified experimentally under the test condition. And, thermo-elastic-hydrodynamic-lubrication (TEHL) analysis is carried out. By comparing analytical results to experimental results, good agreement with experimental result and TEHL analytical result is confirmed. In addition, the influence of bearing load, load direction, pre-load or pad offset ratio on frequency effect is confirmed experimentally and analytically. The results that the frequency effect is larger as bearing load is lower (Sommerfeld number is larger), and the influence of pre-load of bearing on frequency effect is small and that of pad offset ratio (pivot position) is large is obtained.

This paper describes a fundamental study on the seismic safety margin for isolated structures using laminated rubber bearings. The variation of the seismic response assumed in the isolated structures will occur under the superposition of "Variations in seismic response due to input ground motions" and " Manufacturing error of the isolation devices". The seismic response analysis that allows for their conditions is important to assess the seismic safety margin for the isolated structures. The variation of the seismic response due to the superposition of these conditions can underestimate the seismic safety margin of the isolated structures. This paper clarifies that the seismic safety margin of the isolated structure, which consists of rubber bearings and oil dampers, for Sodium-cooled Fast Reactor (SFR) is ensured against the basis ground motions of the Japan Electric Association Guide 4601 (JEAG4601) and the SFR through the seismic response analyses. The seismic response analyses were performed by considering the superposition of the variation factors, such as the input ground motions and the manufacturing error of the isolation devices. Additionally, a relationship between the seismic safety margin and the excess probability of linearity limits was discussed using the results obtained from the seismic response analysis. The required seismic safety margins to satisfy the excess probability of linearity limits were clarified by that relationship.

It is generally known that the groove on tire tread can increase the friction force between the tire and the road surface under wet condition because of the improvement of drainage performance. Although wheel tread of actual railway rolling stocks have a wheel turning trace like the groove on tire tread, the characteristics of tangential contact force of the wheel/rail under wet condition is not clarified in detail. In this study, the tangential contact force measurement using a pair of small cylindrical specimens was carried out to investigate the relationship between the wheel turning trace and the friction force under wet condition. The experimental result shows the friction force under wet condition does not increase due to high iron’s stiffness if the wheel turning trace provided on the tread. On the other hand, it is also confirmed that the wheel turning trace has a reduction effect of the variation of the friction coefficient under wet condition. From the numerical analysis based on these experimental results, it is clarified that the longitudinal vibration of the vehicle can be decreased if the wheel has the wheel turning trace in case of the braking running under semi-wet condition.

Rail corrugation, which causes the vibration and the noise, is a phenomenon in which roughness patterns of approximately regular wavelengths are formed on the rail running surface by trains running. In the previous paper, we have already explained the growth mechanism and the wavelength determination mechanism of the rail corrugation from the dynamic point of view and that there are three stages in the evolution process of the corrugation: formation, growth and saturation. In this paper, we analyze the dynamic characteristics of the track and vehicle in the saturation stage, propose a growth curve of corrugation, and verify them based on measured data obtained on commercial lines. As a result, it is confirmed that when the roughness amplitude grows and exceeds the critical roughness amplitude, there are two characteristics: the significant increase of the contact force fluctuation and the acceleration of the rail and wheel, formation of higher-order roughness components of the corrugation. The growth curve of the corrugation can be approximated by a logistic function.

As a method for the balance assessment, a steady-state response of a subject standing on the support surface oscillating horizontally back and forth at a single frequency has been studied. While past studies on the method have focused on the kinematic analysis investigating the center of mass (COM) motion, there has no research based on mechanical models. The purpose of this study is to present mechanical models that concisely represent the steady-state response depending on the oscillation frequencies. This study implemented oscillation tests on six healthy subjects at 0.4, 0.6, 0.8, and 1.2 Hz. The steady-state response in the test tended to keep the head stationary in space and to suppress the amplitude of the center of pressure (COP). From the analysis based on a double inverted pendulum model, we found a boundary frequency around 0.7 Hz where the body keeps a straight-line and the head can be stationary without using ankle torque. Additionally, the analysis based on the double inverted pendulum model indicated that the steady-state response below the boundary frequency could be represented by a single inverted pendulum model. From comparing the theoretical feedback gain of the ankle torque for making the head stationary in the single inverted pendulum model, we found that the control strategy of some subjects changed significantly at 0.4 Hz. These findings were consistent with the results of the past studies and may be useful for understanding the steady-state response of the oscillation at constant frequencies.

This study investigated the effect of the Mg/Al laminated films, Mg/Al/Pd, Al/Mg/Pd, and Al/Mg/Al/Pd prepared by the pulsed laser deposition (PLD) method, on hydrogen storage/release characteristics. X-ray diffraction (XRD) analysis is performed before and after hydrogenation at 200℃ and 0.99MPa, and then all samples were confirmed to absorb hydrogen. According to differential scanning calorimetry (DSC), Mg/Al/Pd and Al/Mg/Pd released hydrogen at 239 to 452℃ and 173 to 236℃ respectively and Al/Mg/Al/Pd did not release hydrogen. According to pressure-composition-temperature (PCT) line measurement performed at 200℃, Mg/Al/Pd absorbed 1.4 to 3.0 wt.% hydrogen at 0.99 MPa and Al/Mg/Pd film absorbed 1.0 to 1.6 wt.%, that is less than Mg/Al/Pd, and Al/Mg/Al/Pd had an absorption of 2.1 wt.% under the same condition. By electron microscopic observation for the cross section of the films and element mapping by EDS, Mg/Al/Pd was in a state where Mg, Al, and Pd layers were laminated in the order of vapor deposition. In Al/Mg/Pd expect for the Al60/Mg/Pd, Mg diffused into Al to form a Mg-Al solid solution, and Pd was deposited on it. Although Al60/Mg/Pd was in a lamination state like Mg/Al/Pd, the boundary between Al and Mg was ambiguous. Al/Mg/Al/Pd appeared the lamination state in some area and the solid solution state in the other area that means a mixed state. Since the hydrogen storage amount and the release temperature of MgAl solid solution is less and lower than those of Mg alone respectively, the hydrogen storage amount and release temperature of Mg/Al/Pd, i.e., lamination state, is more and higher than that of Al/Mg/Pd, i.e., solid solution state respectively. The hydrogen storage capacity of Al/Mg/Al/Pd was situated between Mg/Al/Pd and the Al/Mg/Pd since Al/Mg/Al/Pd has both states.

Recently bent products are widely applied into various structures. Sharp bending method in bent products has an advantage of fine appearance. On the other hand, it is newly known that origami forming can be applied to freely manufacturing method as fine appearance based on complex folding lines. Sharp bending and origami forming have a common point to require folding lines. Folding lines are produced to make V-groove before bending. At the case V-groove cuttings are carried out for folding lines, it needs machining center plants and working times. So, it is not suitable for mass production. In this paper, we propose new convenient V-shaped punch tools for groove formation in sharp bending and origami forming. So, origami forming can be expected as press method by using V-shaped punch tools. Also this paper reports on the findings of deformation behavior and the mechanism obtained from experiments on groove formation. Some phenomena and necessary punch load in V-groove processing are considered to reveal the mechanism of groove formation based on FEM (Finite Element Method) results and experiments of groove formation by using V-shaped punch tools.

An overlay welding is widely employed to repair damaged components in aged thermal power plants. However, the overlay welding causes heat-affected zone and tensile residual stress which reduce the high-temperature strength of these components. Our research group has reported that a thermal spray technique can reduce the residual stress, while the bonding strength of the repaired part needs to be improved. This study is focusing on a laser metal deposition (LMD) technique as a repairing technique of the damaged component. In order to identify the high-temperature strength of an austenitic stainless steel repaired by LMD, a tensile test and a fatigue test were conducted at 873 K. The tensile test revealed that the repaired part was not delaminated from the base material until rupture, moreover, the yield stress of the specimen repaired by LMD (LMD specimen) is significantly higher than that of the non-repaired specimen. In contrast, it was found that the fatigue strength of the LMD specimen was lower than that of the non-repaired specimen. A fatigue test using LMD specimens without tapered area in the parallel part and a finite element analysis revealed that the low fatigue strength of the LMD specimen is attributed to the residual stress concentrated at the tapered area in the repaired part. The finite element analysis also indicated that the cutting angle of less than 15 leads to the residual stress of less than 100 MPa normal to the LMD/base material interface.

The application of Ti-48Al-2Cr-2Nb (TiAl4822) in such industries as aerospace and automotive has been studied and commercialized in some mass production parts. Additive manufacturing (AM) technology is one of the research areas to expand the application using super alloys. Electron beam melting (EBM), with a vacuum chamber and a heating system, is currently a major technique to build TiAl4822. The present study shows the mechanical properties of additively manufactured TiAl4822 by EBM. There are many reports describing the specific mechanical property or microstructure, but very few reports included the holistic investigation including different mechanical properties such as tensile, fatigue, and creep with observation of microstructure in TiAl4822. In addition, the previous researches reported by different groups applied relatively small specimens with different dimensions and conditions. This makes it difficult to compare the results. In this research, the ASTM specimens for tensile and fatigue tests were prepared adopting same conditions in EBM process to understand the important mechanical properties at 23℃ and 750℃. The effect of test direction on tensile and fatigue properties were evaluated because it has been known that AM gives anisotropic properties. Microstructure was analyzed by scanning electron microscope (SEM) and electron back scatter diffraction (EBSD) to understand the effect of the differences in microstructure on the mechanical properties. The results of tensile test at 750℃ showed that the elongation tested in 45° to the build direction was the largest due to the ductile γ phase is parallel to 45°. Regardless of the stress amplitude, fatigue life in 0° showed the shortest because the relatively low strength between layers could affect the tensile strength in 0°. The fracture surface and cross section of specimen after fatigue test indicated that the delamination between layers can propagate in the material. Fatigue limit in 45° was the greatest, reflecting tensile property in 45°. However, the observation of the cross section after high cycle fatigue test revealed that the delamination between the layers can also occur in 45° because shear stress along the layers is maximum in 45°. In was also found that the anisotropy in EBM specimens in fatigue property depends on the number of cycles, while all the EBM specimens with relatively small grain size showed the longer fatigue life than that of casting specimens. Understanding these anisotropic mechanical properties and microstructure is important when the AM parts are designed.

In this report, we have clarified the cause of damage to the bellows exhaust pipe installed in the hydraulic excavator, and the influence of the seam welded part of the bellows on the damage to ensure the strength reliability of the bellows. First, the fracture surface of the damaged bellows was observed which was installed in the prototype machine of the hydraulic excavator, and it was clarified that the damage cause was the fatigue fracture starting from the seam welded part. Next, the natural frequencies of the engine exhaust system with bellows were derived by eigenvalue analysis, and the main stress frequencies were obtained by the frequency analysis of the stress time waveform measured in the actual machine test. By comparing the natural frequencies and the main stress frequencies, it was confirmed that the repeated shear deformation of the bellows due to the 2nd vibration mode was the main cause of the bellows breakage. Finally, a fatigue test simulating the shear deformation of the bellows was carried out, and it was confirmed that the damage of bellows could be reproduced by the fatigue test and that both inner and outer layers were fatigue-fractured at the seam welded parts. From the above, it can be judged that the seam welded part is the weakest part of the bellows, and the strength reliability can be improved by removing the seam welded part from the high stress part of the bellows.

Soot formation process during coal combustion is one of a key phenomenon to achieve a high-performance furnace. This is because the thermal radiation of soot influences the temperature distribution and the heat transfer process in the furnaces. In this study, polycyclic aromatic hydrocarbons (PAHs) and soot were visualized by a 10 kHz planar laser induced fluorescence (PLIF), laser induced incandescence (LII) and laser induced scattering (LIS) to investigate the soot formation processes in the volatile flame of single pulverized coal particle combustion. In addition, the magnified high-speed imaging was conducted to capture the combustion behavior of the single coal particle. Pulverized coal particles entered high temperature region formed by hydrogen/air diffusion flame in the counterflow. Results showed that five typical combustion behaviors were observed by magnified high-speed imaging. This paper succeeded in visualizing the process from the release of volatile matter to soot formation of single pulverized coal particles with high-speed PAHs-PLIF, LII and LIS measurements. The results showed that the size of PAHs and soot areas was similar, but the duration of PAHs was longer than soot. Also, the PAHs signal was locally high, suggesting that PAHs were directly released from pulverized coal.

Thermal management of electronics is becoming demanding with the miniaturization of integrated circuit and the shift to next-generation high-power electronics. Thermal interface material (TIM), which is typically a mixture of silicone oil and high thermal-conductivity fillers, is often used to remove heat from the chip efficiently by eliminating the air gap between the chip and the heat sink/spreader. However, the interface thermal resistance between TIM and chip/heat sink can become significant due to the depletion of fillers in TIM adjacent to the surfaces of chip and heat sink/spreader. The thermal resistance of the filler-depletion layer (FDL) can occupy half of the total contact thermal resistance when the thickness of TIM is on the order of microns, and thus, preventing formation of the FDL is significant. In this work, we experimentally evaluate the impact of FDL between aluminum (Al) surface and TIM by the time-domain thermoreflectance method (TDTR). The Al surface is modified with four kinds of silane coupling agents before depositing the TIM, aiming to reduce the thickness of FDL. These measurements reveal that the increase of thermal resistance near Al surface is not only caused by the depletion of fillers. When the Al surface is hydrophobic, the thermal resistance increases with the increasing water contact angle due to better wettability of silicone oil to Al surface, repelling the fillers way from the surface. On the contrary, when the Al surface is hydrophilic, the thermal resistance decreases with increasing water contact angle. The direct FIB-SEM observation of the interfacial region between Al and TIM reveals that the small particles are more attracted to the hydrophilic Al surface because of larger gain in the surface energy, and smaller fillers reduces the thermal conductivity of TIM.

The effects of H₂O and CO₂ additions to n-heptane/air mixture on soot formation studied using detailed soot formation model. The simulation model is comprised of gas-phase reaction model and particle formation/growth model. The gas-phase reaction model deals with polycyclic aromatic formation up to 6-ring via molecular growth processes following fuel oxidation and fragmentation. The particulate model is composed of nucleation, aggregation, surface reaction and PAH condensation mechanism. For the fuel-rich condition at the equivalence ratio 3, the numerical analysis was conducted assuming spatially uniform and temporally constant in temperature and pressure. The result showed an increase of soot formation yield ranging from 1700 to 2300K. Adding H₂O and CO₂ to the mixture reduced the soot yield similarly at the reaction time of 1ms. In the gas phase reaction, PAH formation was more suppressed by H₂O addition compared to CO₂ addition. Thus, soot yield at the initial stage of soot formation was smaller for H₂O addition than CO₂ addition. While in particle growth processes, the numerical analysis revealed that the surface growth rate influenced by C₂H₂ concentration was the most dominant and the C₂H₂ concentration for H₂O addition was higher than CO₂ addition. Thereby the particle growth for H₂O addition becomes relatively larger than CO₂ addition with the reaction progress. In other words, CO₂ addition suppresses particle growth due to lower C₂H₂ concentration. As a result, soot formation yields for both H₂O and CO₂ additions reach the same level at 1 msec due to the compensation of the above-mentioned effects of gas phase and particulate processes.

The effects of steam addition on the unstable behavior of hydrogen-air lean premixed flames under the adiabatic and non-adiabatic conditions were investigated using numerical calculations. We adopted the detailed chemical reaction mechanism for hydrogen-oxygen combustion, modeled with seventeen reversible reactions of eight reactive species and a diluent. Two-dimensional unsteady reactive flow was treated, based on the compressible Navier-Stokes equations. The burning velocity of a planar flame decreased as the steam addition and heat loss increased. A sufficiently small disturbance was superimposed on a planar flame to study the characteristics of intrinsic instability. We obtained the relation between the growth rate and wave number, i.e. the dispersion relation, and the linearly most unstable wavelength, i.e. the critical wavelength. As the steam addition increased, the unstable range became narrower, and the critical wavelength became longer. Taking account of heat loss, we obtained smaller growth rates and narrower unstable range. The superimposed disturbance developed owing to intrinsic instability, and then the cellular shape of flame fronts appeared. In cellular flames, compared with planar flames, high (low) concentration of active chemical species was found in downstream of convex (concave) fronts. This was caused by high (low) temperature at convex (concave) fronts due to the diffusive-thermal effects. The concentration of active chemical species became lower with increasing the steam addition and heat loss, which was because of the reduction of flame temperature. Moreover, the burning velocity of a cellular flame increased monotonically with an increase in the scale of premixed flames. The burning velocity of a cellular flame normalized by that of a planar flame increased as the steam addition and heat loss increased. The numerical results denoted that the steam addition and heat loss had a great influence on the unstable behavior of hydrogen-air lean premixed flames.

In Japan, “i-Construction” is promoted to improve the productivity of the construction industries by utilizing Information and Communication Technology (ICT). In particular, estimation of sediment volume at construction sites is highly demanded, for example, in order to pre-order the number of trucks correctly. In current construction sites, the sediment volume is calculated based on conventional terrain measurement methods by using special survey instruments such as a total station. These kinds of methods, however, need a lot of time and manpower. In this paper, we propose a method that estimates sediment volume more easily from three-dimensional (3D) pointcloud data obtained by only sensors installed on a backhoe. Our system is consisted of a LiDAR for 3D shape measurement and a tracking sensor for movement measurement by visual odometry. To obtain dense point clouds, the LiDAR of our system is rotative on a pan-tilt (PT) unit, whose relative relationship between both coordinate systems of LiDAR and the PT unit is estimated beforehand by our calibration method. At construction sites, the backhoe mounting our sensing system measures a ground surface from multiple viewpoints during movement, and a batch of 3D pointclouds of a wide range is integrated by a registration technique. From the whole pointcloud, the sediment volume on the ground can be estimated. In an outdoor experiment, we validated effectiveness of our proposed method by evaluating the accuracy of the estimation results.

This study proposes a method for estimating the positions of vehicles in urban environments with high accuracy. We employ satellite positioning by GNSS for position estimation. Real-time kinematic-global navigation satellite systems (RTK-GNSS) with high precision in satellite positioning can estimate positions with centimeter-scale accuracy. However, in urban areas, the position estimation performance deteriorates owing to multipath errors. Therefore, we propose a method to improve the positioning results by increasing the robustness against multipath using vehicle trajectory. The vehicle trajectory estimates the travel route using the attitude angle and speed. Attitude angles are heading, pitching and slip angle. Trajectories can be generated with 0.5m error performance per 100m. In the proposed method, the trajectory is used as a constraint to solve the multipath of RTK-GNSS. In the evaluation test, the ratio of high-accuracy position estimation improved by up to approximately 30% compared to the conventional method. It is assumed that this method can enhance the development of self-driving cars, AGV control and SLAM technology by eliminating errors and calculating reliability.

Kyphosis causes decline in respiratory and circulatory functions owing to compresses of internal organs. The purpose of this study is to develop a posture keep assist device. The device is constructed with multiple resin components and McKibben type artificial rubber muscle. This device at initial state has a flexibility because the resin components are separated. On the other hand, the resin component can be connected by pressurized artificial muscle. The shape of device in which all resin components are connected imitates spine-curve to fit human back. So, the proposed device can retain entire range of trunk. Target pressure to correct posture is determined from the mathematical model of artificial muscle. In this paper, the structure of device is described, and control method to retain posture based on artificial muscle model is discussed. Finally, effectiveness of the device is verified from experiments in which subject wears this device actually. We reveal correcting trunk posture by using the device from the results.

In order to find effective movements on an office chair for preventing back pain, the paper measures EMG (electromyogram) signal and evaluates cognitive test. Core muscles of subjects on a balance ball are measured when there are forced movement and voluntary movement of the ball. The measurements show the forced movement and discontinuity movement on the ball is more effective in the meaning of muscle activity. The paper also studies the effect of movement with the balance ball on the efficiency of office workers. This is because, even if the movement is good for preventing back pain, it is not desirable to reduce work efficiency. Two cognitive tests, addition test and flanker test, are used to investigate the efficiency of office workers when the movements with the balance ball and no movements with normal chair in the view points of work reduction rate and correct answer rate. The results show the efficiency of office workers is almost the same as the case of movements with the balance ball and no movements with normal chair. Totally the study shows effective movements on the balance ball which activate the core muscle activity efficiently. It also shows the movement does not reduce the office work efficiency.

In this paper, a novel system that remotely operates home appliances is proposed. The system is based on a command space associated with the operation of the home appliance. Thus, a user is able to control the system with simple hand gestures at an arbitrary position. In the system, a pseudo relative coordinate system which is a user-definable coordinate system is applied. The hand waving gesture is detected from the images acquired by multiple cameras installed in the room. Then, the position of hand waving gesture is calculated using the stereo measurement. Next, the pseudo relative coordinate system is defined according to the calculated position. Therefore, it is possible to operate home appliances freely at an arbitrary position chosen by the user. In addition, home appliances are operated using a hand positioning gesture that requires less operation time and less burden than a hand waving gesture. The hand positioning gesture is detected using the frame subtraction and the background subtraction. Experiments verify the operation accuracy and operation time for commands using the proposed system for detailed operations such as TV channel switching.

This paper discusses a nonprehensile manipulation method using a vibrating plate driven by a single actuator. Non-uniform friction distribution is employed to generate three-DoF (degrees of freedom) motion of an object on the plate. First, an analytical model of plate-object system is introduced. Based on the model, the object velocity for given elliptical vibration orbit and surface friction coefficient of the plate is explored. It is revealed that there exists particular parameter setting where the moving direction of the object reversed as the increase of the frequency of the vibration of the plate. Then, three types of non-uniform friction distribution including the particular friction condition are introduced. It is shown that such non-uniform friction distributions have a potential to induce three-DoF motion of the object. Finally, the proposed method is experimentally validated.

A general machine or structure is manufactured by combining a plurality of members, and these members may be used as they are in a simple shape or may be used after being shaped. When performing the dynamic design of such machines or structures by Finite Element Method, it is necessary to input the dynamic properties of the structural members. Here, there is no idea on the effect of the processed part on the overall dynamic properties when the member is shaped. In this study, a steel strip-shaped specimen was used as the target member, and the effect of bending of the member on the modal property was experimentally investigated. And the modal property was reconstructed by Finite Element Analysis with a local damping model at the bending part. As a result, the following conclusions were obtained. From the experiment, for the plain specimen, the relationship between the frequency and the structural damping coefficient was qualitatively and quantitatively constant regardless of the length of the specimen. On the other hand, it was found that the frequency-structural damping coefficient of the L-shaped specimen was not quantitatively constant and could not be expressed by a single function. In order to reconstruct the behavior by FEM, we proposed a method of locally adding a damping element to the bending part. It was found that the relationship between the frequency and the structural damping coefficient of the experimental results can be reconstructed regardless of the length of the specimen and the bending position if the local damping parameter was set appropriately. That is, the validity of the proposed local damping property addition model was confirmed.

When an elevator rope for a high-rise building is forcibly excited by the displacement of the building induced by wind force and/or by long-period ground motion, rope displacement becomes large even if the ground acceleration and the building acceleration is small. Vibration suppressor is used to reduce the rope vibration. The elevator rope is generally modeled using a string with viscous damping. However, the flexural rigidity and the damping property of the rope are not clear yet. In this paper, we proposed a beam model with viscous damping and structural damping. And we also proposed an estimation method of 3 parameters (equivalent flexural rigidity, viscous damping ratio, structural damping ratio). Experiments of forced vibration with/without vibration suppressor and finite difference analyses of rope vibration were performed. It is clear that the identified parameters obtained by the limited conditions of vibration suppressor are applicable to other conditions.

In this study, how to improve usability and quality of the remote participation experience using remote-controlled robots to support the active social participation of people who have mobility issues were investigated. Specifically, to reduce the prediction error caused when using remote-controlled robots revealed in the previous study and thus the burden of the remote operation, a series of experimental results was discussed. In these experiments, the error between the stop position of the robot that cannot be directly seen on the robotic perspective image and the target position was measured. The results show that (1) the zooming image from the robotic perspective during the execution phase induces a negative prediction error. The error might be caused when the information of the current position of the robot is inconsistent with that of the stop position. This result is an extension of our previous study. (2) The above situation needs to be considered because it is assumed in the application of remote operations using robots, such as the need to observe the target information in detail like face-to-face communication. (3) Depth cognition is important for remote control using images from the robotic perspective, and it was found that the information of the optic flow, which was thought to affect the depth motion perception involuntarily, significantly affected the size cue regarding the target position.

Thermal analysis of spacecraft is one of the most important processes to ensure the safety of spacecraft systems. However, the thermal mathematical model has uncertainty such as thermal contact conductance or thermal optical properties. These uncertain parameters in the model are non-negligible for long-term missions because these parameters can change during operation on orbit. Despite the uncertainties, the spacecraft system has only a few onboard temperature sensors compared to large and complex systems. In this study, an advanced thermal analysis method based on data assimilation is proposed to estimate the thermal state of a complex system with limited temperature data. Firstly, this paper describes a new state estimation algorithm called Assisted Ensemble Kalman Filter, which is an advanced state estimation algorithm based on Ensemble Kalman Filter (EnKF). Here, an external estimation algorithm by calculating the heat balance equation was applied to the conventional method to improve the estimation performance of the EnKF. Secondly, we propose a new parameter that indicates observability based on heat flux and temperature sensitivity, and the influence of temperature sensor location on estimation performance was discussed. These proposed approaches were applied to a simple thermal mathematical model, and numerical experiments have confirmed their availability.

This study investigates the effects of initial imperfection and mesh resolution on the wrinkling and creasing. Finite element analyses are conducted to simulate compression behaviors of an incompressible Neo-Hookean elastic plane with a V-shaped notch as initial imperfection, so that the occurrences and evolutions of wrinkle and crease are evaluated quantitatively. As a result, it is demonstrated that the origins of wrinkle and crease can be determined by the overall and local strains even for the introduction of a V-shaped notch. Further, we illustrate that the converged specific local strain with respect to the increase of mesh resolution almost coincides with the condition of the occurrence of wrinkle (i.e., ε_w = 0.456) when the depth of a V-shaped notch is sufficiently small. We also show that the sizes of wrinkle and crease do not converge due to strain localization around a V-shaped notch. In the investigation of pattern evolutions about initial imperfection, we illustrate that two kinds of pattern evolution can be comprehensively discussed by varying the depth of a V-shaped notch, so that the condition of the occurrence of crease can be organized by the sharpness of a V-shaped notch.

We attempt to construct a novel automation technology based on the hammering task and its sound feedback process with an industrial humanoid robot equipped with an integrated system of vision, sound and dual arm motion. First, we focus on a musical saw to achieve a tuning motion as its basic study because it is considered to be difficult to control a kind of unknown and unclear tool under beginning operation. Second, we discuss its characteristics to develop the tuning motion based on dual arm motion and sound feedback system. Third, we attempt to cooperate on hammering task by right arm and bending task by left arm for the musical saw with estimating its hit sound. As a result, it can be seen that the proposed system using an industrial humanoid robot makes it feasible to achieve sufficient tuning motion for the musical saw such as unknown and unclear tool. Therefore it is demonstrated that the proposed approach is found to be useful to construct the automation technology based on the hammering task and its sound feedback process with an industrial humanoid robot.

Reliability-based design optimization (RBDO) is one of design optimization techniques considering uncertainty and has gained attention in the engineering design. To reduce the number of function evaluations in the RBDO, many studies using response surface have been conducted. It has been recognized that sampling strategy plays an important role for highly accurate reliability analysis as well as the reduction of function evaluations. In this paper, reliability-based global optimization with a novel sampling strategy is proposed. The proposed sampling strategy consists of two parts. In the first sampling strategy, several sampling points are added around unexplored region in order to achieve the uniform distribution of the sampling points. Second sampling strategy adds a new sampling point at one of Most Probable Target Points (MPTPs) for improving the local accuracy, in which the new sampling point is selected by the distribution of sampling points. In addition, a deterministic formulation of the RBDO is conducted to search global optimal solution efficiently. Through numerical examples, the validity of the proposed method is examined.

The prevention of an arteriosclerosis, which is a major cause of death in the world has social significance. In previous studies, blood vessel elasticity was estimated by using parameters of blood vessel model. However, the effect of wave propagation on the estimation was ignored. It is not clear how these features affect the estimation of blood vessel elasticity in clinic. In this study, the coupled model of blood vessel and blood flow based on the coupled wave theory was proposed on the assumption that the viscosity is more strongly influenced by blood flow than by blood vessels. Identifying the model parameters of elastic pipes subjected to cyclic pressure fluctuations by using measured pressure and displacement data, we concluded that the coupled model may be applicable for estimating the vessel stiffness in clinical practice.

In Fukuyama City, Hiroshima Prefecture, there are two main roads, National Road No. 2 which crosses the city from east to west, and Prefectural Road No. 244 which crosses the north and south. National Road No. 2 has the role of connecting Fukuyama City to the city in the east-west direction, and Prefectural Road No. 244 is an artery for logistics to the industrial area in the southern part of Fukuyama City. Therefore, the traffic of vehicles passing through these main line roads are high. If such a main line road is congested, for example, when traffic is too high and traffic congestion occurs, such as in the morning or evening commuting hours, many vehicles that want to avoid traffic congestion will enter the road in a residential area. As a result, it is expected that it will negative effect for the safety of roads in residential areas. The authors investigated the area around the crossing of National Route No. 2 and Prefectural Road No. 244. And the authors analyzed traffic volume on main line roads and residential areal roads, questionnaires from junior high school students in the investigate area, traffic accident occurrence situations, and traffic situation data using the ETC 2.0 function. In this study, it was confirmed from traffic volume observations and ETC 2.0 data that the traffic volume on residential roads parallel to the main road increased during the time of congestion on the main road. In addition, regarding this parallel residential areal road, "the place where junior high school students had a dangerous experience" coincided well with the locations where sudden braking frequently occurred in the ETC 2.0 data, and there were many actual accidents.

In the early stages of chassis model-based development, we needed a tire physical model that could be handled easily, and we devised the TM tire model. Some tire samples have verified that the TM tire model is superior to existing physical property models. The feature of the TM tire model is that is improved the modeling of tire tread parts. This improvement has made it possible to embody the mechanism of the cornering force in the small slip angle range. In this paper, we theoretically prove that the way of thinking of the TM tire model has universal validity and explain its mechanism.

This study aims to establish a new restriction of ballast renewal works at a low temperature in winter. The authors construct a FEM model of railway track which simulates the ballast renewal work at a low temperature and perform the FEM analysis under the various conditions of track radius of curvatures R, length of ballast renewal work L and decrease in rail temperatures Δt. As a results, it becomes clear that the inward rail displacements and changes in axial rail forces increased with the decrease in R, and the increase in L and Δt. Based on FEM results, the authors propose the restriction diagrams of ballast renewal work which provide the allowable decrease in rail temperatures from the neutral temperatures of rail newly welded under the restriction of converted temperature of changes in rail forces, inward rail displacements and alignment defects due to inward displacements. Furthermore the authors propose the flow for users to judge propriety of ballast renewal work at a low temperature by use of the restriction diagrams. Consequently, the ballast renewal work at a low temperatures exceeding the current restriction can be executed.

Previous study has shown the effectiveness of twisted morphing wing with a double-cylinder structure. The purpose of this study was to obtain the knowledge on the appropriate cross-sectional shape of the outer cylinder in the double cylinder structure in order to achieve high bending rigidity and low torsional rigidity simultaneously. The theoretical formulas about the bending and torsional multi-beam structure in the outer cylinder were derived. The effectiveness of the theoretical formulas was demonstrated by comparing with the numerical simulation using solid elements. It was observed from the results that high bending rigidity and low torsional rigidity can be achieved by having the aspect ratio of the cross-sectional shape far from 1. Finally, in order to obtain knowledge on the cross-sectional shape that can achieve high bending rigidity and low torsional rigidity, Pareto front was investigated. As a result, it was found that the aspect ratio of the cross-sectional shape should be set smaller than 1 after the beam length was set appropriately.