In this study, PM exhausted from unsteady pool flame of iso-octane on a shallow dish under various ambient temperature conditions (25 – 700°C) was investigated as fundamental study of fuel film combustion. Flame appearance from ignition to combustion end under various ambient temperature conditions was observed. Further, total masses of CO₂, CO and PM emitted from the flame during flame formation period were measured by gas analysis and filter method. In addition, the effect of lubricating oil addition in fuel on PM and combustion gas emitted from unsteady pool flame were investigated. As the result, it was found that total mass of CO₂ emitted during flame formation period decreased with ambient temperature rise, and total mass of CO and PM increased with ambient temperature rise. Moreover, it was found that the iso-octane with added lubricating oil (5wt%) emitted less CO₂ from the flame compared to the fuel without the lubricating oil addition.

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 by flame quenching process, a laminar pool flame of toluene was quenched using a 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 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 flame. In addition, True density of PM was measured by a Pycnometry system. As the result, the true density increases towards the downstream part in the flame, and the true density of Through-PM was higher than Deposit-PM. Furthermore, oxidation characteristics of PM was measured by a Thermo Gravimetric Analyzer. As the result, it was considered that the oxidation temperature of PM at downstream part in the flame was higher than that of PM at upstream part in the flame.

Combustion origin particulate matter (PM) has different characteristics such as hydrophilicity and hydrophobicity depending on the combustion method, however it is difficult to separate each PM characteristics. In this study, to develop selective PM sensing system using a quartz crystal microbalance (QCM), PM adsorption characteristics on the QCM surface was investigated. PM emitted from a pool flame of hydrocarbon fuel such as toluene was supplied to the QCM, and the frequency shift of the QCM was measured. In addition, polystyrene coated QCM with hydrophobic and acetylcellulose coated QCM with hydrophilic characteristics were also investigated.

Next-generation drone needs a high energy density, long life, and light weight portable power source. This work focus on a combined power system consists of micro gas turbine and high-speed generator. In recent years, combustion using porous media has been attracting attention due to factors such as high power output relative to weight. Combustion using porous media offers advantages such as extending the flammability limits and reducing the emission of pollutants. However, it has been found that combustion at the microscale can negatively impact flame stability and other factors.In this study, we conduct experiments on microscale combustion using a liquid fuel with limited research on porous media combustion and potential use as a biofuel - ethanol.

Modern society faces major social problems such as the future depletion of fossil fuels and the acceleration of global warming due to the increase in greenhouse gases resulting from their use. On the other hand, the demand for energy will continue to increase due to population growth and economic growth. In response, carbon recycling and decarbonization efforts are underway. To this end, our laboratory has been conducting experiments on thermochemical decomposition of carbon dioxide using metal oxides as reaction media in order to decompose carbon dioxide into oxygen and carbon monoxide for use as fuel. In this experiment, ceria was used as the reaction medium. Experiments were conducted using Ar/CO₂ gas as the carrier gas in a non-isothermal cycle with varying temperatures during reduction and 1200°C during oxidation. No peak was observed for O₂ production, but a peak was observed for CO production, and the higher the temperature during reduction, the more CO was produced.

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors plan to introduce a seismic isolation system. When the sloshing wave height is small, it can be approximated with a linear vibration model. However, when the sloshing wave height increases and the sloshing becomes nonlinear, it is necessary to evaluate the wave height using other methods such as numerical analysis. Although the evaluation of nonlinear sloshing wave height is important, there are few examples which quantitatively evaluate the wave height of nonlinear sloshing. This paper reports on the development plan and an overview of the evaluation method for nonlinear sloshing wave height and load applied to cylindrical tanks.

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors plan to introduce a seismic isolation system. When the sloshing wave height is small, it can be approximated with a linear vibration model. However, when the sloshing wave height increases and the sloshing becomes nonlinear, it is necessary to evaluate the wave height using other methods such as numerical analysis. Although the evaluation of nonlinear sloshing wave height is important, there are few examples which quantitatively evaluate the wave height of nonlinear sloshing. This paper reports the results of the sloshing water test carried out to obtain test data for the construction of the evaluation method and the results of the reproduction analysis carried out using the VOF method.

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors plan to introduce a seismic isolation system. When the sloshing wave height is small, it can be approximated with a linear vibration model. However, when the sloshing wave height increases and the sloshing becomes nonlinear, it is necessary to evaluate the wave height using other methods such as numerical analysis. Although the evaluation of nonlinear sloshing wave height is important, there are few examples which quantitatively evaluate the wave height of nonlinear sloshing. This paper reports on the study result of the predictive evaluation method for nonlinear sloshing wave height and impact load acting on the flat roof applied to cylindrical tanks.

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors plan to introduce a seismic isolation system. However, the natural frequency of first order sloshing may be close to the response frequency of the Sodium-Cooled Fast Reactor with the seismic isolation system, and the sloshing wave height is expected to increase. When the sloshing wave height increases, the sloshing becomes the nonlinear sloshing, which can't be evaluated by linear sloshing theory. In order to evaluate the sloshing loads, which act on the roof and the internal structure, the nonlinear sloshing liquid surface shape and the nonlinear sloshing flow velocity are necessary. Therefore, the authors studied the predictive evaluation method of the nonlinear sloshing for the liquid surface shape and the flow velocity with simplified equations. This paper reports on an overview of this predictive evaluation method.

In order for Shinkansen pantograph to exert good current collection performance, it is important to keep appropriate pantograph lift force during high-speed operation. In particular, lift force characteristics of the pantograph head is designed in consideration of changes in the external shape due to wear of the contact strip. However, in rare cases, lift force may decrease depending on the extraordinary wear of contact strip or other unexpected damage of pantograph head. When an external force is applied to the pantograph head in that state, long-time contact loss may occur, and it is important to understand the relationship between lift force characteristics and dynamic behavior of pantograph head. Therefore, based on simple mechanical model, we conducted a theoretical study of pantograph head behavior in various lift force characteristics and clarified the relationship between difference in initial speed and behavior of the pantograph head.

Vibration characteristics of rotary machines depend on the critical speed map determined by the rotor structure, also the stiffness and damping characteristics of bearing and its surrounding structure supporting the rotor (bearing support structure). It is important to deal with and design the rotor-bearing system unitarily to obtain the desired vibration characteristics, however, there are numerous parameters of the system and this make its design comlicated. In this study, a simple design method was proposed to predict the stiffness of the bearing support structure using annular rubber components, and validation with experimental measurement of the vibration chracteristics was conducted. The measured vibration chracteristics of the rotor-bearing system accorded qualitatively with the one predicted by the proposed method, and critical speeds were well matched quantitatively after expanding the method with considering dynamic characteristics. We have considered the proposed method is simple and applicable to designs of rotor-bearing systems with bearing support structure using rubber components.

In the present paper the attention is focused on reduction of strange noise generated from rectangular cylinders in cross flow. The width-to-height ratios of was 3.0. The tube pitch ratio in the transverse direction was 8.0. We measured the aerodynamic sound radiated from the rectangular cylinders in the range of Reynolds numbers from about 10³ to 10⁴. The several high peaks were formed at the spectrum of SPL. The two peaks of the spectrum of Strouhal number of 0.08 and 0.2 were caused by vortex shedding from the two horizontal rails of 16×30 mm and rectangular cylinders of 5×15 mm, respectively. On the other hand, the strange noise occurred at five times the vortex shedding frequency. This noise is caused by the vibration excited by the vortex shedding at the natural frequency. We have discussed how to counteract the noise generated by rectangular cylinders.

Surges occur in compressor systems including turbo compressor at low flow rates. Surges not only degrade the performance of the compression system but can also damage the compressor system. There have been few studies on low-flow rate centrifugal compressors, and their characteristics are still unknown. In this study, the behavior and generation process of surges in small-flow centrifugal compressors were investigated. As a result, it was found that surges occur even in very low flow rate compressors, and that pressure fluctuations occur, which may be a precursor to the surge.

This study investigates the phenomenon of in-line vibration of a square prism, one of the structural elements, in the flow direction. A control plate is installed at the corner of the surface of the square prism to investigate the effect of control plate length and porosity on the flow-induced vibration. In the experiment, the test model was installed in a free vibration apparatus that can vibrate only in the flow direction in a wind tunnel, and the flow-induced vibration response characteristics were investigated by changing the length and porosity of the control plate. Instantaneous displacement of the model was measured by means of Laser Displacement Anemometer. From the experimental results, it was found that the vibration effect obtained differs depending on the method of mounting and shape of the control plate. Therefore, the method used in this study can suppress the displacement of flow-induced vibration in the-line direction.

Cup transport systems are machines that print on plastic cup, and air nozzles are used to separate, hold, and release the cup. Since air nozzles eject the high-pressure air into the atmosphere, fluid noises, e.g. 96.3dB(A) from printing mandrel part and 90.8dB(A) from supply spiral nozzle, are generated. It causes to worse work environment and disturb the improvement of cup production speed. The purpose of this study is to investigate the noise characteristics of the supply spiral nozzle (inner hole nozzle) used in a cup transport system and to take measures to reduce noise. In the experiment, compressed air was supplied from an air compressor, and the noise level, cup flying distance, and frequency characteristic of noise were measured. As a result, it was found that by using the inner hole nozzle with diameter of 0.8mm and 2 holes, 8.6dB(A) of noise and 43% of flow rate was reduced compared to the actual nozzle. The frequency analysis clarified that the noise with dominant frequency of 16kHz was reduced by inner hole nozzle.

This paper deals with sloshing suppression and energy dissipation due to internal flow in a rectangular vessel with double bulkheads. In this study, first, the effect of double bulkheads spacing on the sloshing suppression characteristics is clarified experimentally. Next, the effects of bulkheads aperture height on the sloshing suppression characteristics are clarified for double bulkheads. The relationship between internal flow in the vessel and suppression characteristics is also investigated by experiment and PIV. As a result, the more the two bulkheads are inserted equally spaced in the vessel, the more effective they are in the suppression of the sloshing. In addition, the deeper the bulkheads are inserted, the more effective they are. Furthermore, it is found that the sloshing energy is dissipated by the vortex and swirling flow generated in the vessel, creating a sloshing suppression effect. Finally, the fluid forces acting on the bulkheads are clarified by numerical analysis, and the characteristics of multiple bulkheads are discussed.

In this experimental study, fluid dynamic response characteristics of wake galloping between two rectangular prisms of different size in tandem and staggered arrangement to their relative position and free stream velocity were investigated. An immovable rectangular prism at upstream side and another vibratile square prism was placed at downstream side. The vibratile prism at downstream side is elastically supported at it is both end and is restricted to vibrate in only cross-flow direction. From the experiments, it was found that the response characteristics can be classified in terms of relative position and free-stream velocity. Then the wake galloping phenomena occurred in the free-vibration experiments were reproduced by forced-vibration experiments in a water channel to conduct flow visualization. The visualization results well explained the phenomena observed in the wind tunnel experiment.

Piping systems in nuclear power plants exhibit significant elastic-plastic behavior before failure due to displacement responses under severe seismic loads. The current Code Case (JSME NC-CC-008) that was published in 2019 considers the elastic-plastic behavior of the piping system itself but assumes elastic behavior for the support structure. Hence, future Code Case upgrades should incorporate the inelastic behavior of piping support structures. The JSME task group conducted benchmark analyses of piping support structures to establish an evaluation method for their inelastic behavior. The objective of the benchmark analysis was to evaluate the influence of analysis parameters in the elastic-plastic analysis of piping support structures and gain knowledge on analysis result variability. This paper presents an outline of the benchmark analyses and their progress.

In the piping design of nuclear power plants and chemical plants, a clearance is required between the pipe and the supporting part that supports it so that the pipe can move in the pipe axial direction in order to allow thermal expansion of the pipe in the pipe axial direction. Due to the clearance, the supporting part of the pipe becomes a loose structure with gap. Hence, the structure causes impact vibration during earthquakes, resulting in dissipation damping and impact load. In this study, since the vibration mode of the piping changes before and after the collision phenomenon of the piping, we propose an analytical model of piping impact vibration using a beam model for the pipe and a spring-mass system model for the support part. In particular, we discuss the relationship between the vibration of the supporting part and the coefficient of restitution by using the one-degree-of-freedom spring-mass system model of the supporting part, which is a main part composing the proposed analytical model for impact vibration of piping systems.

A realistic fragility assessment must be performed to recognize the weaknesses of structures. It is important to set the failure mode appropriately for a realistic fragility assessment. Previous studies have shown that the failure mode of piping systems during earthquakes is fatigue. Conversely, the basis for considering the failure mode of piping systems to be fatigue is based on the occurrence of fatigue under dynamic loading conditions and does not indicate that ductile rupture does not occur. In a study on the ductile rupture of elbow piping, we conducted an in-plane bending test on a full-scale model of a carbon steel elbow. A previous work showed that gradual deformation in the opening and closing direction did not cause ductile rupture. However, there are few experimental data on the ultimate state of elbow piping with ductile rupture of out-of-plane bending. In this study, static tensile loading tests and static cyclic loading tests of carbon steel elbow pipe in the direction of out-of-plane bending. the tensile tests showed that ductile fracture did not occur even when the elbow pipe was subjected to out-of-plane bending deformation with a plasticity factor of 40. Therefore, the possibility of the ductile rupture of elbow pipes during earthquakes is extremely low. In the cyclic loading tests, fatigue cracks occurred at elbow pipes.

Car bodies used in railroads are subjected to a variety of vibrations. Not only in the vertical direction, but also in out-of-plane, torsional, and elastic vibrations, and high order harmonic modes. When people are on board during operation, the vibration frequency that affects ride comfort is around 8 Hz. In general, it is known that lower damping can reduce the elastic vibration of the car body. On the other hand, the damping remains low all the time, other vibrations may cause resonance and have small effect on vibration reduction. In this paper, to improve ride comfort in the car bodies, the author proposed and developed a unique oil damper with a long orifice filled with a ball. When the ball blocks the orifice at large amplitude of vibration, high damping force is occurred. While the ball is passing through the orifice at small amplitude, low damping force is derived. In this paper a prototype damper was manufactured, and resisting force characteristics were measured experimentally.

The necessity for rapid initial responses to enhance urban resilience, especially in the wake of earthquakes, forms the core of this research paper. Critical to this process is the immediate assessment of structural damages, necessitating the application of structural health monitoring systems. The burgeoning interest in employing Information and Communication Technology (ICT) and sensor technologies for disaster prevention and mitigation is explored, with particular emphasis on the role of smartphones. Given their widespread prevalence, this research proposes a methodology that utilizes image data from smartphone cameras to measure structural displacements using deep learning. The paper delineates the efficacy of this approach through experimental verification, demonstrating its viability and effectiveness in practical scenarios.

In Japan, cotton is frequently used as a cushioning material in the transportation and long-term storage of art objects. Despite its frequent use, there is almost no information on the cushioning properties of cotton, such as cushioning curves. Therefore, the presenter started an effort to understand the characteristics of cotton as a cushioning material. As a result of the drop impact test, it was not found that the maximum acceleration change of a single layer of cotton has a minimum point. Therefore, we conducted the same experiment with two layers of cotton, and found that the minimum point exists around from 2.5 × 10^-3 [kg/cm²] to 3.0 ×10^-3 [kg/m²]. We considered that this phenomenon indicated that the maximum acceleration varied linearly with respect to the static load, because the thinner the cotton, the less resilient it was. On the other hand, it could be considered that when cotton has some thickness, its restorative force increases, and thus it has optimal static load conditions.

Industrial accidents caused by natural phenomena such as earthquakes and floods are called natural-hazard triggered technology accidents (Natech) and have recently been considered important for the maintenance of social functions. However, there are not enough test and analysis results that contribute to the evaluation of the functional limit of machinery and equipment considering a large-scale elasto-plastic region in maintaining the function of industrial equipment. In this paper, we focus on piping systems during earthquakes and investigate failure modes and evaluation methods of functional maintenance limits of piping systems through FEM analysis and loading tests. In addition, FEM analysis will be performed when cyclic displacement is applied to one end of an elbow piping system assuming a cyclic loading test. Analysis will be performed on the piping before and after plastic deformation to confirm how the load-displacement relationship is affected by the generation of residual strain, and the results of the analysis will be summarized.

In this paper, we study method of model reduction of connected vehicle. A car model consists of 1 body, 2 trucks, 4 wheel sets, and has 21 degrees of freedom. The connected vehicle model is made up of 10 cars and has 210 degrees of freedom in total. It is considered 21 cases of input waves (7 patterns of sinusoidal waves whose frequencies are 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0Hz and 3 directions of excitation: East-West, Up-Down, North-South), and 60 modes are chosen by sparse estimation in each case. Then, in order to reveal which modes do/do not depend on input waves, we suggested ‘multiplicity’ of modes as an evaluation index of that. If the index is high, it is seen that the selected modes do not depend on input waves because the modes are chosen in many cases, and if the index is low, it is seen that these modes depend on them. As a result, about a half of 60 modes were chosen in all cases of input waves (multiplicity: 7). Moreover, we made the common reduced-order-models by using 28, 38, 45 modes whose multiplicities are high (5-7), and these models were able to reproduce the response behavior of the connected vehicles.

Japan is one of the most earthquake-prone countries in the world, and there are concerns about the safety of current nuclear power plants. Therefore, the development of SMR (Small Modular Reactor) with high safety rationality is promoted. However, an appropriate seismic isolation system for SMR has not been determined. Therefore, we will study a seismic isolation system using laminated rubber. In this study, the nonlinearity in the large deformation region of laminated rubber is introduced into the analysis model and its influence is evaluated.

Japan is one of the most earthquake-prone countries in the world, and recent experiences of major earthquakes have expanded the scope of application of seismic isolation systems, and there is a need for more sophisticated earthquake countermeasures. This study introduces an additional spring element to suppress locking vibration at the top of the air-floating unit based on the knowledge of air-floating technology that the authors have been developing, and summarizes the performance evaluation results from shaking table tests focusing on maintaining horizontal isolation performance under simultaneous vertical and horizontal inputs.

This paper deals with the response behavior of the multi-connected vehicles subjected to seismic excitation. The multi-connected vehicles are modeled by a set of vehicle models that have 21 degrees of freedom. The running road is modeled by mass, spring and damper system that have 1 degree of freedom each of three directions. Passengers are modeled by mass, spring and damper system that have 1 degree of freedom each of two directions. Passenger model are placed in 4 locations on the car body. Since the analysis of this multi-connected vehicle is complicated, we made the reduced order model by using sparse estimation. We investigated the influence of passenger characteristics on reduced order model. As a result, the more complex the passenger variation becomes, the more modes are needed to reproduce the behavior of the original model. In addition, modes in which passenger moves mainly account for about a quarter of the modes extracted by sparse estimation.

This paper describes damping mechanisms of vibration reduction system with granular materials. A granular impact damper has a damping effect by enclosing particles in a container that also serves as the main vibrating part. In this paper, experiments were conducted with different diameters and quantities of particles, and image analysis of the particles inside was performed. The results show that the motion of the particles relative to the container affects the damping and that the damping ratio tends to increase with an increase in the number of particles when the particles are sufficiently small. In addition, a granular impact damper was modeled using a Non-Smooth DEM and numerically analyzed using the same parameters as in the experiment and compared with the experimental results. The results revealed important factors in the numerical analysis, their issues, and discussed a proposal to modify it.

In this study we aim to realize an actuator that is comparable with a natural muscle from a viewpoint of flexibility, the output force and the responses. We constructed the Shape Memory Alloy (SMA) actuator protected by “a Rolled Film Tube” with the high heat resistance and the high flexibility. A coil spring made of SMA wire with rectangular cross section was acquired at last study. In this study, we made a motor unit with seven coil springs made of SMA wire with rectangular cross section. The main body of the motor unit was inserted into the natural rubber outer tube to prevent coolant leakage. However, the natural rubber outer tube deteriorated quickly and was insufficiently flexible in the axial direction. Therefore, we proposed a coolant recovery system (lymphatic system) that reuses the leaked coolant as lubricant and an open type outer tube that does not require dripproof is adopted. As a result, in present study, the maximum output force was 10.3N and the minimum time constant is 1488ms. Prior to this experiment, as a result of an experiment on one coil spring made of SMA wire with rectangular cross section, the maximum output force was 2.5N and the minimum time constant was 170ms. Therefore, in the near future, the maximum output force of the motor unit can be increased to 17.5N and the minimum time constant can be shortened to about 200ms.

The prosthetic hand we have developed is powered by air pressure, and its functionality is not impaired even when the finger joints are flexibly deformed. This makes it possible to grasp objects of various shapes, and it has the advantages of durability and high safety for the user and others. We have evaluated the performance of the developed prosthetic hand and conducting user tests using only the prosthetic hand. Of the 22 tasks performed, 16 were successfully completed. The user was able to achieve movements that were comparable to those of normal subjects in the task using grip strength grasping. The results of the user test confirmed several issues regarding the functionality of the prosthetic hand, but it was thought that it could sufficiently fulfill the purpose of assisting bimanual motion in an environment where children actually use the prosthetic hand.

We have been developing precise positioning control system for general purpose pneumatic actuators, where less than 0.1 μm steady state error in linear drive and less than 1/1000 deg. in rotary type are already achieved. The proposed method is not a main controller but just a compensator, which enables us to switch between apply or remove the output signal from the compensator on demand. Currently, cooperative robots have attracted many attentions in the product line from view of lowering of labors in the super aging society. In such a robot, safety must be ensured since they are standing beside of the human worker and, at the same time, precise motion control is also required to implement assembly work. In our proposed method, precise positioning control with high gain servo loop and compliance servo property owing to the air compressibility can be switched according to the work. In this study, fundamental control properties and sample of industrial application are introduced.

Responsive polymers that express actuation functions controllable by external stimuli are expected to be deployed in soft robots and soft actuators. In particular, light-responsive polymers can be used for non-contact actuation and remote/local control. In this study, we verify that the photothermal conversion characteristics of the motion induced by infrared light irradiation of an elastomer film containing liquid metal (LM). The first is the study of Marangoni propulsion on the water surface, and the second is the study of the bending motion of polyimide/LM-containing bilayer film in air.

Microfluidics is a continuously growing field, of great interest in chemistry, physics, drug discovery, biology, chemical biology, biomedical research, and most recently soft electronics, soft sensor devices. To date, polydimethylsiloxane (PDMS) is the most popular material in research laboratories for the fabrication of microfluidic devices.

In this study, we present an easy step acrylonitrile butadiene styrene (ABS) scaffold-removal method for achieving auxetic micrometric channels in a single block of PDMS.

Soft robots employing soft polymer materials such as gels and elastomers have various advantages such as compact, lightweight, and silent motion. Recently, biomimetic structures driven by pneumatic control have been attracting attention though various driving sources have been proposed. In this study, we fabricate cylinder-shaped soft robot with an armored (exoskeleton-like) auxetic structure with a negative poisson's ratio that placed around bellows-typed tube. Moreover, we investigated the structural variability and walking performance of the armored cylinder structure.

In this study, we designed the multiple semi-bellows type arms driven by pneumatic control, and attempted post-functional operation after pre-fixation in order to utilize the three-dimensional deformation of their actuator functions. In that case, Kirigami structural top plate was fixed, and two-dimensional expansion deformation of the fixed Kirigami top plate synchronized with the bending motion of the arm was examined.

The fabrication of shape-changing structures has been positioned as a core seed for future technologies that will contribute to the development of aeronautics and minimally invasive surgery. In particular, the use of soft gels and elastomers can be expected to enable rapid and diverse shape deformation. Furthermore, it is possible to dynamically control the deformation from a two-dimensional sheet to a three-dimensional structure by introducing air. It has been reported that, for example, a camouflage structure by pneumatic control inspired by the skin deformation of an octopus, and a Gaussian surface that can be freely deformed by devising a flow pattern. In this study, we fabricated a structure with auxetic structural deformation of the rotation mechanism using a 3D printer and investigated the mechanical 3D deformation.

An ionic polymer-metal composite (IPMC) actuator is an electric driven soft actuator that deforms in response to voltage. It is produced by chemically plating gold on an ion-exchange membrane. Because of their flexible motion, IPMCs are attracting attention for application in the medical field and biomimetic robots. One of the characteristics of IPMC is high formability as it is possible to configure multiple actuators and sensors in a single device by cutting and dividing the electrodes on the surface, which is called patterning. Previous works found that patterning causes interference of the input signal of the IPMC with other separated electrodes. In this study, we aim to realize precise displacement control of the patterned IPMC actuator by considering electrical interference of driving signals. In this paper, we fabricated the patterned IPMC and analyzed three types of frequency responses of electrical interference, displacement, and sensor signal.

Hands play a very important role in humans, allowing us to grasp, touch, and manipulate objects. In previous studies, several types of pediatric prosthetic hand have been developed. However, a 2-DOF (Degree of Freedom) wrist joint that can move freely and intuitively like human wrist has not been developed. In this study, we developed a monolithic-structured multi-DOF pediatric prosthetic hand with a 2-DOF wrist. By using a compliant mechanism that uses deformation of an elastic hinge, the number of parts can be reduced while maintaining the degree of freedom. Therefore, the proposed structure is superior in terms of movability and assembly cost compared with conventional structure. Fingers and wrists are designed to achieve the human joint range of motion. In evaluation experiments, we confirmed that fingertip force for grasping and wrist strength in compression are sufficient for the specifications required in daily life. Finally, we fabricated a prototype using a 3D printer and demonstrated the feasibility of the proposed mechanism.

In this research, we developed a mechanical loads measurement system for the stairs handrail during walking up. This system is composed of the handrail part including sensors and 3 steps stairs. The handrail material is midair SUS304, and has 2 strain gauges installed on it. and the height of the riser and length of the tread were based on standard dimensions for public facilities. The 3-axis force sensor is installed between the handrail and pillars using jigs for measuring mechanical loads perpendicular to the handrail. Using this system, 5 healthy adults participated in the experiment by walking upstairs. As a result, the total affecting time of the mechanical load against the handrail is about 1.396 s, normalized maximum load is about 0.036 N/N. Also, the mechanical waveforms graphs showed different behaviors,: Two participants' waveforms are positive at all phases, but one participant showed positive and negative phases, which means that both pushing and pulling action were performed.

Efficient risk assessment is essential for addressing secondary disasters such as gas leaks, which can be triggered by primary disasters like earthquakes and tsunamis. However, traditional personnel-led inspections, despite the use of safety gear, pose significant risks. In complex environments, microdrones offer advantages but encounter challenges related to sensor capacity and operational time. Therefore, this research proposes a collaborative approach using multiple microdrones equipped with diverse sensors to detect gas leaks. These microdrones are operated remotely and collect environmental data, including temperature, humidity, and gas concentration. The acquired data is utilized for computational fluid dynamics (CFD) analyses to estimate the source and spread of the gas leaks. This paper presents the development and testing of a sub-100g microdrone specifically designed for gas detection and discusses potential improvements in leak detection through the visualization of airflow around the drones.

In gait rehabilitation, training using a treadmill is one of the effective means. In particular, there is a need for a system that automatically changes speed according to the intention of the walker. In order to realize natural automatic speed adaptation of treadmills, this study focuses on the interaction force between the pedestrian and the treadmill, and aims to develop a control method that responds to the pedestrian's movement. To this end, we constructed a control system for a treadmill that controls the change in the pedestrian's centrifugal velocity by detecting the kicking force from the pedestrian and adjusting the load given to the pedestrian. Then, we conducted a walking experiment on a treadmill for an adult male subject using the control system, measured and analyzed the motion, and investigated and verified the interaction force and change of centrifugal velocity during walking.

We created the middle ear model with conductive hearing loss and researched about the screening for conductive hearing loss. A coupled model of external auditory meatus, eardrum, and auditory ossicle using leverage was considered to reproduce the normal ear in our former research. In this study, we studied the response while changing the ratio of the length of malleus to that of incus to reproduce the ear with conductive hearing loss. As the ratio decreased, the sound pressure transmitted to the inner ear decreased, which was considered to be close to the condition of conductive hearing loss. Furthermore, the power spectrum of the displacement of the eardrum also decreased at the same time. Next, since the sound pressure in the inner ear cannot be measured directly, the displacement of the eardrum was used as a method to determine the presence of conductive hearing loss. We tried to estimate the ratio of the length of malleus to that of incus from the power spectrum of the displacement of the eardrum. If we estimate the ratio, we may be able to estimate the progression of conductive hearing loss. And then, we proposed a method for screening conductive hearing loss and simulated it. The results of the analysis indicated that the power spectrum could be used to screen for conductive hearing loss. We investigated the modeling error since the true modeling for patients’ ears cannot be reproduced by our modeling perfectly. We laid the foundation for an algorithm that can infer ear conditions.

In this research, an endoscope insertion device is studied for the purpose of automating colonoscopy. The insertion device must simultaneously perform axial forward/backward movement and rotation of the endoscope, and the use of a mecanum wheel in the insertion device will achieve this movement. However, since the mecanum wheel has only been used as a wheel for plane movement, it is necessary to clarify the relationship between the endoscope clamping force of the mecanum wheel, the feed force and speed, and the amount of movement of the endoscope itself. In this study, a simulation analysis of the feed rate was conducted, followed by experimental verification of the analysis results．

In this research, we are studying and developing a self-propelled catheter that utilizes the peristaltic movement found in nematodes and other worms. The catheter is driven by water pressure, and water is pumped through the septum in the operating chamber and through the holes that allow fluid to pass through, causing the operating chamber to expand sequentially to achieve peristaltic motion. However, manufacturing the mechanism for peristaltic motion is extremely difficult because it requires the use of elastic materials such as rubber-like materials. To solve this problem, we used a 3D printer that can use elastic materials. Through this attempt, the previous study succeeded in fabricating a catheter capable of peristaltic motion. However, the mechanism was slow because the amount of movement of one motion was small, so it was necessary to increase the speed by increasing the amount of movement of the mechanism. In this report, we design and develop a mechanism with an increased amount of movement per movement, and confirm through experiments whether the design is optimal for improving the movement speed.

In our previous study, we developed a passive-type assistive device: Polycentric Biomimetic Knee Joint (PC-BKJ). PC-BKJ mimics the knee joint motion by combining two gears and assist knee extension from deep flexions using reaction force of liner spring. However, PC-BKJ was limited to use in the assist of standing movements on level ground. In this study, we develop a Semi-Active PC-BKJ (SA-BKJ) with a Variable Reaction Force Mechanism (VRFM) to improve usability and expand the usage applications. In this paper, we reported the basic structure of the SA-BKJ and movement evaluation of SA-BKJ.

This study focuses on developing a normally close magnetorheological fluid device for assistive robots, which ensures safety by preventing torque loss during unexpected power off. The device uses both electro and permanent magnets to create torque even without power supply. To confirm the reduction of the magnetic flux, magnetic field analyses were carried out for several patterns. As a result, a segmented model magnet with axial magnetization was adopted. If the magnets are too close to each other, the direction of the magnetic flux is affected. For this reason, a 45° magnet was employed rather than a 75° magnet. Torque measurements of the developed device were conducted. The device generated about 0.5 Nm in off state. When current was applied, the torque was reduced to a very small value of 0.05 Nm at 200 mA. When the reverse current was applied, a torque of 5 Nm was generated at 1000 mA.

This report describes the results of reducing residual stress during press forming by changing the diluent water for the lubricating film in cold forging from tap water to softened reform water. Tensile tests were performed on bonded low-carbon steels, and surface strain was compared by image correlation method. Since the difference in adhesion was clear due to the difference, press forming experiments were conducted on thin sheets subjected to the same bonder treatment. We investigated the friction coefficient experimentally and applied it to CAE analysis. Furthermore, as a result of changing to this dilution water for bonder treatment of mass-produced processed products, the forming load was also reduced.

The effects of surface roughness on the molecular gas lubrication (MGL) characteristics have been studied in order to confirm the application limit of the MGL equation against the surface roughness. The study has been done by comparing the calculated results by the MGL equation with those by direct simulation Monte-Carlo (DSMC) method which is expected to give more correct solution. In previous study, the ideal roughness model, which has sinusoidal or triangular wave form, has been employed, though more practical random rough surface is used in this study. The digital filters and Fourier transformation are applied to the generation of random roughness, and the characteristics of the roughness are adjusted by changing the filter parameters. The numerical analysis was performed against the 2-dimensional shear flow consists of stationary rough surface and moving smooth surface. It is clarified that the increase of transverse flow, which is neglected in the MGL equation, causes the difference of results obtained by using the MGL equation and DSMC method. The roughness slope of the surface significantly effects the generation of transverse flow. The difference of both calculation methods starts to increase against the roughness slope greater than the specific value. These characteristics, resulted from this study, are same as those shown in the previous study and it is confirmed that the roughness slope plays an important role on the applicability of MGL equation in spite of roughness configuration.

This report deals with a method for comprehending real contact situation by measuring complex refractive index in contact surface. For the contact surface where spherical samples were pressed against a glass plane, the distribution of complex refractive index was measured experimentally and was estimated by Hertz contact theory and the optical model in which the multiple reflections inside the gap between surfaces were considered. For the BK7 glass lens sample, the measured index was equal to the physical property value in the contact and non-contact region both in air and in water and was accounted successfully for by the multiple interface model in the region where the index slowly changed. For the silicon lens sample, the measured index was not equal to the physical property value but showed a proper value in the contact region both in air and in water. From the above it is suggested that this method enables identifying sample material as well as judging contact situation.