It has been clarified through various studies that the cutting edge spacing and density of abrasive grains on the work surface affect the accuracy and tool life in machining with grinding tools, but there has been no research on the effect of the dispersion of abrasive grain distribution. Therefore, this laboratory has proposed a method to quantitatively evaluate the abrasive grain dispersibility of grinding tools by using information content entropy from images transferred by pressure-sensitive paper. However, when quantitative evaluation using information entropy is performed, there is a possibility that the distribution state differs even if the evaluation value is the same. In this paper, we improved the entropy evaluation by changing the number of divisions of the evaluation area and applied it to the evaluation of silicon carbide grinding belts. As a result, there were few changes in the grinding belt, such as shedding and glazing, and there was no significant difference because no extreme distribution occurred. In the future, it will be necessary to conduct measurements on grinding wheels, which are prone to changes, and on different types of grinding belts to compare the results.

Many of the machine elements are made of wood in the Pre-modern Ages in Japan, which makes material processing including wood cutting work technologically important. Wood cutting work, usually provided in a divisional system, differs from metal cutting work, mainly provided by smiths, and manufacturing in a composite system can also be provided including material processing of some composites made of both metal and wood, or material processing with machinery. The aim of this series of papers is to study how material processing and manufacturing was provided in the Pre-modern Ages in Japan.

JAMSTEC has been developing an underwater laser scanner for some time. The specifications are intended to partially complement the performance of sonar technology and camera technology. In addition to sonar technology that is effective for wide-area exploration from a long distance and camera technology that is effective for narrow-area exploration from a short distance, it will be a new exploration technology that contributes to middle-range exploration from a medium distance. The purpose of this research is to further expand the middle-range exploration capability from the medium distance, and to construct an advanced long-range underwater laser scanner that is more practical and provides an overwhelming amount of information. We are now developing a laser ranging evaluation system to acquire and evaluate the basic data. This paper gives an overview of the evaluation system.

In this study, we are developing a method for sequentially calculating the scan points that can obtain the shape of the entire object high-densely in 3D laser measurement. For the calculation, we do not use prior information, but utilize the low-density part of the point cloud obtained by the scan to determine the point. In this method, the point cloud that is already sufficiently dense is scanned again if it is in the vicinity of low-density area. In contrast, if excessive scan is prohibited, even if a large number of low-density points can be rescan, scan will not be allowed if there are high-density points around the points. To solve this problem, we have introduced a process to select a point where many low-density points can be scanned with high density and where the ratio of excessive scan is low. In this paper, we show the results of scan simulations using the proposed method on two kinds of 3D models of cultural properties and applying the evaluation criteria of English Heritage.

In the real contact measurement by ellipsometry, there is a problem that the measured complex refractive index changes gently at the contact/non-contact boundaries. In this report, the multiple reflection in the gap between contact surfaces was considered in the optical model which was used to estimate complex refractive index. The sample measured results for a glass plane pressed by a glass lens were successfully accounted for by the estimation by the optical model which considered the gap of layered structure. Thereby, it could be possible to improve the accuracy of real contact judgement by excluding the influence of multiple reflection in the gap on the estimation of complex refractive index.

In this study, we present an improving method to increase an accuracy of the visual hull with a pseudo higher resolution technique for a low resolution image. A pixel of images was separated to 4 subpixels, and each pixel value of the subpixels was calculated from the density gradient surrounding the target pixel. Thus, a subpixelization with a pseudo higher resolution technique was performed. In this study, images of a three-dimensional human shape was taken with 8 cameras virtually. In the first time applying this technique to the images, the obtained silhouette shape was smaller than the actual ones. Also, the visual hull was smaller than the actual shape. On the other hand, in the second time, the silhouette shapes were spread, and then the visual hull was larger than the original shape. The subpixelization technique could smooth the silhouette shape excessively, and it could decrease the essential the contour shape. To increase the reproducibility of the contour line, it could be necessary to modify the subpixelization technique. Also, uniform subpixelization might be useful to improve our method, since the calculation of pixel values should affect contour shapes.

To evaluate the effect of medications for osteoporosis, a prediction and estimation of the changes in bone structure caused by the bone metabolism are needed as well as the mechanical adaptation of the bone. In this study, we embedded the bone metabolism cycle in the bone remodeling law that depended on surrounding stress. The bone metabolism was consisted of the duration for resorption of 4%, formation of 16% and rest of 80%, and the condition was decided by the brightness of voxels of images. We performed the bone remodeling simulation using the finite element method, and compared the case of only stress uniformization with the one of the bone metabolism that embedded in the stress uniformization. As result in the case of the metabolic cycle, the porosity and the volumetric bone mineral density showed small values. Also, the major orientation angles of the bone showed the 2nd and 3rd direction in addition to the 1st direction. These results could indicate that the bone metabolism was needed to reconstruct the bone cross bridge additional to stress adaptation of the bone.

This paper presented a fabrication of rehabilitation device driven by pneumatic actuators. When damaging a finger, it's difficult to take back usual movement. The rehabilitation added to the symptom is needed. We propose the new devices with which rehabilitation of a hand is supported. A device for rehabilitation is driven by pneumatic bellows actuators. We confirmed to the fabricated device are able to move winding and extension motions.

There is a need to realize a power assist device that takes safety into consideration for use by hemiplegic patients and the elderly. The authors have newly proposed to avoid excessive support torque mechanically, and have developed an operation support mechanism by pushing and pulling an elastic cable. This report discussed the development of finger joints support devices for the index and middle fingers, and gripping force. In this experiment, the rotating of the motor with a sine wave drive to the driving the sliding screw, which make the mechanism flexions and extensions. As a result, a maximum gripping force of 11.35N be obtained. However, the desired gripping force could not be obtained due to the low cable holding capacity of the mechanism. Further improvement is needed.

Vascular smooth muscle cells (VSMCs), which align in the circumferential direction of the vascular wall, regulate vascular contraction and dilation. They actively remodel the vascular wall in which they reside through biochemical and biomechanical signals. However, mechanical environments in vivo are quite different from those of cultured cells: VSMCs in vivo show an elongated shape and form a tissue that aligns with the circumferential direction of the walls. In addition, it maintains its contractile capacity while continuously receiving tensile stimulation. Thus, in the present study, we used the micro-grooved PDMS substrate that mimics the elongated cell shapes and alignment observed in vivo. We found that VSMCs on the micro-grooved PDMS substrate changed elongated shape and their nuclear morphology to a slim shape similar to the nucleus of a cell in vivo which consequently improved SMC differentiation. Furthermore, we constructed an experimental method in which cyclic stretch stimulation is continuously applied in the direction of cell alignment, as in an actual arterial wall. The actin cytoskeleton except around the nucleus was reorganized obliquely to the direction of 10-60° from groove direction, although the cell body and the actin cytoskeleton around the nucleus maintained their orientation to the grooves. The results suggest that cell alignment and cyclic stretch stimulation can lead to more similar remodeling to F-actin in VSMCs in vivo.

This paper describes a wall-climbing robot with insect-inspired claws, which can stay and move on rough vertical surfaces by hooking the claws on surface asperities. A crawler device with twenty-four fishing hooks was used as a propulsion mechanism to stabilize adhesion. A running test was carried out on sandpaper surfaces with various surface roughness. The test results show that the robot can move on sandpaper surfaces with particle sizes of #40 and #60 and inclination angles of 30 °, 60 °, and 90 °. However, the crawler became more slippery and the moving distance became shorter at large inclination angle.

This paper describes a wall-climbing robot inspired by insects, which can move on a smooth slope and ceiling using surface tension. The adhesion mechanism of the robot is based on the system of ants, where the vertical force is the meniscus force and the horizontal force is the frictional force of rubber. In order to use the meniscus force during moving on the slope and ceiling. we installed two pieces of adhesion pads made of glass. One was installed in front of the robot and the other was installed under the axis of the wheel. The weight of the robot was 11.2g, Since the measured the maximum withstanding weight of one adhesion pad was 30g, we believed that the adhesion pad can support the weight of the robot. The robot moves by dragging the adhesion pad using its wheels. The experimenter results shown that the robot can successfully move 150 mm, 270 mm, 105 mm, 60 mm, and 100 mm as the angle of the slope is 60°, 70°, 80°, 90°, 180°, respectively.

In this study, we constructed a flapping robot based on a hummingbird, measured the change in ascending force according to the size of its wings, and selected an appropriate feather. The created Hummingbird Robot was 7.0 [g], and when the gravitational acceleration of 10 [mN] was converted into a value of 70 [mN], the ascending force was necessary. Since the hummingbird flies by twisting (feathering) of its wings, we fabricated 3 types of feathers in which the area of the feathering part was changed, and conducted experiments. We succeeded in generating a maximum 74 [mN] force from the experimental results. We succeeded in improving the ascending force by increasing the area, but when the area was increased, the force to lift the wind was dispersed, resulting in a decrease in the ascending force due to the flexibility of the material of the wings It resulted in.

In this paper, we report on a system for measuring anger in a Virtual Reality (VR) environment using Micro Electro Mechanical Systems (MEMS) force sensors. Anger was induced by a game using VR, and a MEMS force sensor was embedded in a fingertip stick to measure the gripping strength. When anger is triggered by the game, the strength of the grip increases. The video images and sensor measurements during the game are stored on the PC via wireless communication, enabling the game to be played in a VR environment. The game was actually played and the force was measured. The player's emotions during the game were measured by a questionnaire after the game. We were not able to obtain a reliable correlation between force and anger, but by building a force measurement system in a VR environment, we were able to generate anger and build a system that could measure it.

Objective of our research is to realize a sequential self-folding method by devising a hinge structure. Sequential self-folding methods have been researched in order to fabricate complex microstructures using origami structure. Previously, a method by a directed heating of pre-stressed hinges, a method using a difference of the rate of absorption of light between printed ink colors, and a method using a difference of the shape recovery speed due to the difference of compound shape memory polymers have been researched. However, if the number of hinges is large, the locally heating method requires many heating processes and the method using material characteristics takes a lot of time and effort to fabricate structures. In this paper, as a method that requires fewer heating processes and enables to easily fabricate structures, we examined the sequential self-folding method of the whole heating of structures with a heat shrinkable polymer sheet by making slits in the passive layer. Specifically, in a bilayer structure consisting of a passive layer with slits and a heat shrinkable layer, we investigated control the self-folding start temperature by the slit length, the number of slits and the plate length. We clarified that the longer the slit length is, the larger the number of slits is and the shorter the plate length is, the higher the self-folding start temperature is. Moreover, we demonstrated our sequential self-folding method by the structure with two hinges whose self-folding start temperatures are different.

On a thermoelectric generator (TEG) , p-type and n-type thermoelectric elements are generally used to make a device. When a TEG is composed of p-type and n-type materials with different electrical and thermal properties, the performance of the entire device may be degraded by either the p-type or n-type element if the element shape is the same. In this study, we calculated the maximum power per unit area of the π-type TEG by theoretical calculation and simulation using a finite element method. The maximum power per unit area was calculated by changing the electrical and thermal conductivities, and the results indicate that the power increased by changing the area between p-type and n-type when these properties were different. In addition, when the thermal conductivities are different between the p-type and n-type thermoelectric elements, we found that the results were different between simulation and theoretical calculation, because a temperature gradient is created at the substrate of the low-temperature side.

We measured the three-dimensional behavior of gold nanoparticles by measuring their position in the height direction using the defocusing method due to the small size of the observation target. As the amount of blur, we used the maximum value of the second-order derivative of the intensity value to approximate a Gaussian distribution in relation to the distance from the focal point. In the experiment, the aperture was narrowed down because the kurtosis was larger when the aperture was narrowed down and the measurement was easier. The frequency was varied from 300 kHz to 1 MHz and applied to the planar electrodes. When taking images with the microscope, we focused on the glass substrate and set the measurement area in front of the focal point, and 7 μm above the glass substrate in the height direction. The defocusing method was used to measure particles in the height direction, which showed different behaviors by changing the frequency applied to the electrodes. When frequency at which the interconnects are self-healed was applied, the particles showed a behavior of gathering at the electrode gap, which is thought to be due to dielectrophoretic force. On the other hand, when frequency at which the interconnects aren’t self-healed was applied, some particles approached the electrodes, but the particles did not stick to the interelectrode space and moved away.

The 140th Anniversary Hall was built at Tokyo University of Agriculture and Technology in 2011 as a building to verify the actual performance of energy-saving facilities with renewable energy. During the actual operation of the building, it was observed that the heating did not work because the hot water obtained by the solar thermal collectors did not have usable temperature. Therefore, this study aims at improving the performance of heating based on solar thermal by simulation. A simulation tool, TRNSYS, was employed to model the air conditioning system. The results of the analysis suggest that an auxiliary heater is effective to utilize solar thermal energy, and that the area of the solar wall is possibly adjusted to maximize the performance. Solar thermal use is predicted to reduce the fuel consumption of heating down to 20% for 2 months in winter.

Thermoacoustic phenomenon is interconversion between the acoustic energy and the thermal energy. This phenomenon can be used for engines, electric generators and refrigerators. Thermoacoustic devices have several advantages: They have no moving components, resulting in high reliability and easy maintenance. They are external-combustion system and have a flexibility for choosing a heat source. Since the thermoacoustic refrigerator driven by solar heat uses natural energy and does not use toxic refrigerant, it may be a solution to various environmental problems such as global warming. It is possible to increase the energy density of solar energy by concentrating the sunlight by using a parabolic reflector or a Fresnel lens. The refrigerator and sunlight collector are separated, so the cooling power is improved by fixing prime mover. In this study, the loop type tube with branches was adopted, and the performance was evaluated.

The air-conditioning system used in this study installs an insulating growth space within an agricultural greenhouse. At the ceiling of this growth space, vinyl tubes that allow groundwater to pass through are placed Since the groundwater temperature does not change so much throughout the year, it can be used as a heat source for heating in winter and cooling in summer. In this study, we conducted an experiment on the cooling capacity in summer. Results show that the temperature in the growing space was relatively high although the cooling effect was a little high. Furthermore, the relationship between the solar irradiation energy and the cooling amount of this system was also evaluated.

Penguins use a pair of wings to perform agile swimming maneuvers such as sharp turns and rapid acceleration. In previous studies on penguin swimming, 3D motion analysis for forward swimming and visual observation of turning swimming have been conducted. 3D motion analysis of turning swimming, however, has not been conducted. Since turning swimming is an important ability involved in foraging preys and escape from predators, it is essential for understanding the swimming mechanism of penguins. In this study, in order to reveal the mechanism of penguins in turning swimming, we filmed penguins at a zoo from multiple directions with underwater video cameras. We attached tracking markers to representative parts of the penguins and conducted 3D motion analysis, and a single sequence including left turn was analyzed. As a result, the penguin seemed to turn left during upstroke and move straight forward during downstroke, although the contributions of the left and right wings to those turning behavior is still unclear. During the left turn, the penguin bent the neck leftward so that the angle of attack of the head was small, suggesting that the drag of the head was minimized by the neck bending.

Coleoptera is characterized by hardened forewings, called elytra. While some beetles open the elytra during flight (four-wing flyer, 4WF), other beetles flap their wings without opening them (two-wing flyer, 2WF). We hypothesized that the status of the elytra affects the flight performances, such as efficiency and stability. Using synchronized high-speed cameras, we have filmed the flight of two model species, Anomala albopilosa (4WF) and Protaetia brevitarsis (2WF). Their wing kinematics have been reconstructed by tracking the landmarks on their body and the wings. Using wing morphology and kinematics, we have performed the computational fluid dynamic analyses of the beetles to evaluate their aerodynamic performances. We found that the effect of elytra is relatively low in terms of lift and thrust generation, while the opening elytra may affect flight dynamics by generating additional drag. The results suggest that the status of elytra may reflect the trade-off between flight efficiency and flight maneuverability.

Urolithiasis is a disease in which calcium oxalate crystallizes in the urinary tract, and has a high recurrence rate. It is necessary to consider the burden on the body by surgical treatment, therefore, treatment methods that effectively promote spontaneous stone passage are required. In this study, to develop a working accelerated renal pelvis and calyx simulator, we visualized the orbit of a renal callus model by using a physiological 3D renal pelvis and calyx model and an acceleration motion experiment system. According to analysis from experiments, it was confirmed that the simulator is able to reproduce spontaneous stone passage similar to our experiment results. By establishing a spontaneous stone passage prediction simulator, it will be possible to devise a method to effectively promote spontaneous stone passage in patients. By reducing the morbidity of urinary lithiasis that requires surgery, it is expected to reduce the burden on patients and medical sites.

Flapping wings are expected to be beneficial to small flying robots in terms of the large lift with large angle of attack in low Reynolds number flow. We are focusing on hummingbirds which are the only birds capable of sustained hovering flight, and are conducting research toward the realization of small flying objects that imitate them. Although the wing flexibility can improve the aerodynamic lift and efficiency, resultant flow field around the flexible flapping wings have not been fully understood yet. Here, we created two types of hummingbird-mimetic wings and compared their lift, efficiency, and flow field by means of an electric flapping mechanism and PIV (particle image velocimetry). The design difference between the two wings was the number of wing shafts: one has four shafts and the other had eight shafts. The flow field on the wing cross sections near the mid-stroke was two-dimensionally visualized at the flapping frequency of 20 Hz. As a result, the leading-edge vortex was found to be attached to the 4-shafts wing at distal region, producing notable downwash. The efficiency of the 4-shafts wing was better than that of the 8-shafts wing while the lifts are similar to each other.

In this study, we investigate the morphology and phase diagram of self-assembled polymeric nanoparticles (NPs) confined within nanotubes (NTs) by dissipative particle dynamics simulations. There is a clear relationship between the self-assembling architecture of nanoparticles (NPs) and their physical properties, and Polymer-tethered NPs, which are created by grafting polymers onto NPs to control the self-assembly of NPs, have attracted considerable attention. However, self-assembled structures have not been systematically classified because of the large number of tuning parameters such as the polymer length and graft density. In this study, we investigated the confinement of NPs grafted with three types of polymers: hydrophilic, hydrophobic and Janus surface, hydrophilic and hydrophobic walls. First, we derived the qualitative phase diagram of the axial pressure Pz and the ratio L of NT radius to NP radius. As a result, in polymer-grafted NPs with Janus amphiphilic surface, hydrophobic and hydrophilic polymer tether NPs were found to assemble axially to form an ordered structure, and in hydrophobic NTs, a double helical structure was formed at L=3.0. These simulation results show that the self-assembled structure of polymer tether NPs can be qualitatively predicted based on the chemical properties of NT walls and the surface design of polymer tether NPs.

Hydrogen peroxide plays a variety of roles such as sterilization and bleaching in industry, formation of oxides in the atmosphere, and stress signalings in biological cells. Elucidation of the properties of hydrogen peroxide will lead the further understandings of these roles. The aqueous structure formed around hydrogen peroxide and its dynamics have been clarified using various approaches such as spectroscopic experiments and quantum chemical calculations. In this study, we performed quantum mechanics / molecular mechanics (QM/MM) simulations to investigate the effect of hydration structure on the structural dynamics of hydrogen peroxide in an aqueous solution from the perspective of temperature dependence. We find that the relative stability of the dihedral angle of hydrogen peroxide increases according to the decrease in temperature, which follows the Arrhenius law. At low temperatures, the relaxation dynamics of the hydrogen bond formed between hydrogen peroxide as a donor and water molecules as an acceptor becomes slower than that at high temperatures.

Fluids confined in nanochannel exhibit distinct phases and flow properties not shown in the bulk. These confined systems are involved in many industrial and engineering applications such as nanofluidic devices, biological membranes and therefore understanding and controlling the molecular behavior of confined liquids is important. Octamethylcyclotetrasiloxane (OMCTS) is a small macrocycle made of four covalently linked Si(Me)2O units which have been used as a model liquid in the experimental studies. However, much less is known about the mechanisms related to external stimuli such as shear and how those molecular behaviors in a confined system impact the flow properties of the whole liquid. In this study, we have investigated the structure and shear viscosity of OMCTS confined between two mica walls under shear, using molecular dynamics simulation. The results showed layering of OMCTS molecules, depending on the distance between two mica surfaces. In addition to this, the structural changes were observed accompanied by shear-thinning behavior when we applied shear to the system.

Biomembranes are composed of various types of lipids and proteins and are generally known to be laterally heterogeneous. In biomembranes, the heterogeneous field is formed via a phase separation into the ordered Lo domain, which is rich in saturated lipids and cholesterol, and the disordered Ld domain, which is rich in unsaturated lipids and is fluid. In particular, the Lo domain is called a lipid raft and plays important roles in cell functions such as signal transduction and immune response. The diffusion of molecules in the heterogeneous field is thought to affect the process of searching for interaction targets to perform their functions. Here, we perform mesoscale simulations to investigate the diffusivities of molecules in different heterogeneous fields. The effects of the heterogeneity in the fields, molecular interactions, concentration, and field preference, on the diffusivities of particles were analyzed. We find that the differences in diffusivities were produced according to the difference in diffusion coefficients between the two phases and the distribution of residence times in the two phases. Increasing the particle concentration or strengthening the intermolecular interaction increase the aggregation of the diffusing particles, resulting in a decrease in their diffusivity. Moreover, the diffusivities depend on the type of barrier, i.e. preference of Lo or Ld domains.

With their recent miniaturization and integration, heat accumulation in power semiconductor devices is becoming a big issue. To tackle this issue, nanoporous membrane-based evaporative cooling devices have been proposed which can potentially dissipate a heat flux of ~1 kW/cm². Porous membrane-based evaporative cooling devices have recently been developed which can dissipate a heat flux of ~1 kW/cm². The optimized design of these devices requires an understanding of the non-equilibrium gas flow near a liquid–vapor interface, namely the Knudsen layer. Although the direct simulation Monte Carlo (DSMC) method has been widely adopted for analyzing rarefied gas flows, a DSMC approach to low Mach-number flows suffers from a high computational cost due to large statistical noise, hindering a detailed understanding of the nonequilibrium gas flow in the Knudsen layer. Furthermore, heat transfer in porous membranes together with fluidic transport through pores significantly affects evaporating-flow behavior. In this study, we propose a method which combines a continuum-based approach to the solid- and liquid-phase analysis and a low-variance deviational simulation Monte Carlo (LVDSMC) approach to the gas-phase analysis. Boundary conditions are imposed at gas–liquid, liquid–solid, and gas–solid interfaces, ensuring the continuity of heat and mass fluxes through these interfaces. Using the coupled simulation technique, we thoroughly investigate the effects of convection in porous membranes, the aperture ratio, and the Knudsen number on the evaporative heat flux.

We have addressed a cubic magnetic particle suspension in an alternating magnetic field in order to investigate the time change in the internal structure of particle aggregates by means of Brownian dynamics simulations. In a relatively weak magnetic field, when the magnetic particle-particle interaction strength becomes predominant, cubic particles aggregate to form closely-packed structures with a perfect face-to-face configuration. Because the orientation of the magnetic moments of constituent particles is strongly restricted due to the influence of the magnetic particle-particle interaction between neighboring particles, they do not follow the change in the direction of the alternating magnetic field. As the magnetic particle-field interaction strength is increased, the closely-packed clusters completely collapse and transform into elongated aggregates with an offset face-to-face configuration since the magnetic moments of constituent particles incline in the magnetic field direction. We conclude that a regime change in the aggregates of cubic particles in an alternating magnetic field may be induced by magnetic particle-particle and particle-field interactions.

Studies on jet direction control methods without variables or moving parts have been drawing attention. Several attempts have been made to control the direction of the primary jet using a secondary flow with a Coanda surface. In this study, the direction of the primary jet was controlled by applying a synthetic jet with the Coanda surface as the secondary flow. Specifically, the effect of the rigid boundary on the deflection characteristics of the jet was investigated experimentally by applying flow visualization. In this study, the geometric shape was constant. Additionally, the dimensionless frequency, momentum ratio, step length, and offset ratio were used as experimental parameters. The results demonstrated that the deflection characteristics of the jet near the wall surface depend on both the offset ratio of the wall surface as well as on the momentum ratio between the primary and secondary jets and the dimensionless frequency of the synthetic jet.

An attempt was made to elucidate the influence of a bluff body installed near the jet outlet slot on the flow characteristics. In this study, the synthetic jets were applied as the jet flows and a circular cylinder was applied as a bluff body, and the experimental study was conducted. The flow fields of synthetic jets were visualized by the smoke wire method and they were observed. It was found that the behavior of the synthetic jets may differ from that of the continuous jets owing to the interference between the vortex pair formed at the slot exit and the vortexes formed in the wake of the circular cylinder. In this study, it was confirmed that the flow field strongly depends on the dimensionless frequency under the condition that the cylinder installation position is constant. In the range of this experimental condition, when the dimensionless frequency is large, the behavior of synthetic jets are similar with the continuous jet. However, it was observed that the jet separated into two direction at the specific dimensionless frequency and developed in the vertical direction.

When a single-slotted circular cylinder with tangential blowing is installed downstream of the main jet, the deflection characteristics of the main jet depend on the position of the circular cylinder. However, there are few reports on the application of multiple-slotted circular cylinders with tangential blowing for the main jet vectoring. In this study, the flow around a double-slotted circular cylinder installed downstream of the main jet was experimentally investigated. The visualization results of the flow field around the circular cylinder of the single and double slots were compared. Specifically, the relationship between the deflection angle of the main jet and the installation position of the circular cylinder was considered. It was found that the deflection angle of the main jet depends considerably on the installation position in the single-slotted circular cylinder, whereas its dependence on the installation position is not significant in the double-slotted circular cylinder.

In order to achieve efficient cooling of motors, this study aims to clarify the effects of changes in rotation speed and flow rate on the flow structure of a liquid film in a rotating coaxial cylinder simulating a motor. To quantify the cooling performance, the flow structure of the liquid film in the narrow space is clarified. The experimental results show that the liquid flow velocity in the nozzle and the thickness of the liquid film on the cylindrical surface increase with the increase in the rotation speed. This was especially noticeable at the near part of liquid inlet. The flow at the far from the liquid inlet is greatly affected by the flow rate.

Recently, electric vehicles (EV) have been gradually becoming popular, and EV motor have been developed accordingly. The heat inside motor affects the performance of the motor, it is necessary to cool the motor. Currently, oil-cooling motor are being developed for efficient heat removal. However, the flow inside oil-cooling motor is unknown. To improve the heat removal efficiency of oil-cooling EV motors, it is necessary to clarify the flow behavior inside the oil-cooling motor. The purpose of this study to elucidate the flow behavior of gas-liquid two-phase flow in a narrow gap between rotating coaxial cylinders, such as that inside an oil-cooling motor. As a preliminary step to elucidating the flow behavior of gas-liquid two-phase flow in a narrow gap between rotating coaxial cylinders, we investigated the effect of rotation speed on the air single-phase flow. We used PIV and Image analysis to evaluate the flow field, clarified distribution of flow velocity in a narrow gap between rotating coaxial cylinders.

Variable inlet guide vanes are installed at the impeller inlet in fluid machines, such as centrifugal compressors, pump turbines, and swirl generators. They are used for flow rate control, flow angle adjustment, reduction of the collision pressure loss at the blades, and expansion of the operation range. However, if the blade angle of the inlet guide vanes is set to be small, flow instabilities with a specific frequency occur downstream of the vanes. It is known that such unsteady flow is a two-dimensional phenomenon, and vibrations occur owing to the circumferential propagation of the cell structure. This study attempted to experimentally clarify the influence of the circular cylinder set at the outlet of the device on the flow instabilities generated downstream of the guide vanes. The pressure fluctuations were measured. Consequently, it was demonstrated that circular blockage can suppress the flow instabilities.

A DBD plasma actuator (DBDPA) has been expected to be widely used in flow control applications due to its high versatility. On the other hand, the energy conversion efficiency of the DBDPA is very low and increasing the jet speed is an important issue that must be overcome for the practical application of the DBDPA. As one of the solutions to this problem, the acceleration of induced jet flow by applying an external magnetic field has been studied. In this study, the relationship between the magnetic field and the induced jet flow was experimentally investigated by measuring the behavior of the induced jet flow using a particle image velocimetry (PIV) under the condition that a permanent magnet or a non-magnetic stainless steel were placed on the back of the DBDPA. As a result of measuring the velocity fields, acceleration of induced jet flow was observed in both cases of magnets and stainless steel on the back of the DBDPA. In addition, it is suggested that the external magnetic field is expected to increase the efficiency only when low voltage is applied to the DBDPA.

An experimental study was conducted focusing on the interaction between gas bubbles adhering to the surface of the rigid boundary and cavitation bubbles produced near the gas bubbles. In a sufficiently large water tank, gas bubbles of arbitrary size were placed on the surface of the boundary, discharge cavitation bubbles were produced, and the subsequent behaviors of the gas and cavitation bubbles were photographed with a high-speed camera using a halogen lamp as a light source. In this study, the interaction of bubbles was discussed, while focusing on the variation in the cavitation bubble centroid with time. The main parameters are the bubble size ratio and relative distance between the bubbles and rigid boundary, and the migration characteristics of the cavitation bubble were classified into three types based on the direction of centroid movement.

The aim of this study is to evaluate the bubble generation behavior for the practical use of the air leak measurement system for pneumothorax patients. The method for measuring the air leak flow rate has already been developed, using the bubble volume and bubble generation frequency in the chest drainage unit. One of the problems for the practical use of this method is that the flow rate is calculated with the bubble volume as a constant value. However, it is known that the bubble volume changes depending on the amount of drainage accumulated in the chest drainage unit and the flow rate flowing into the unit. Therefore, we investigated the correlation between the pressure wave and the bubble volume for the development of air leak measurement system that can compatible with changes of bubble volume. We discovered that there is a correlation between the pressure difference when a bubble separates and the bubble volume. We succeeded in measuring air leaks with high accuracy using the bubble volume estimated from the pressure wave.

The use of levitated droplets with electrostatic and ultrasonic fields has attracted much attention in the fields of materials development, chemical engineering, and so on. In order to use them properly, it is essential to understand the internal and external flow of the suspended droplets. The flow inside fluid droplets is visualized with the particle image velocimetry (PIV) method. The fluid that is to be investigated is scattered with small particles that follow the flow well. One problem that occurs when the PIV method is used to measure velocity fields inside droplets is however that light refracts at the droplet surface and the internal flow curvature is distorted. The aim of this research is to visualize the curvature distorted internal flow of an acoustically levitated droplet. The curvature distortion is successfully visualized using the PIV approach based on the calibration method. In this study, the curvature distortion illustration was performed based on the refractive indexes and aspect ratio. The experimental results showed that the internal flow curvature can be distorted in two types such as barrel, pincushion distortions, and increase as the refractive index increases.

When high purity and large diameter are desired in manufacturing single crystals, defects due to “oscillatory thermocapillary” are inevitable in the crystal. The oscillatory convection is caused by “Hydrothermal wave instability”. We performed the tomographic stereo PIV on thermocapillary flows with thin liquid films for understanding the three dimensonal structure of Hydrothermal waves. As a result, the flow structure of Hydrothermal wave was captured and reconstructed sucsessfully.

In the imaging of chemical reactions using near-infrared absorbance characteristics, the problem is that the regression model constructed based on the spectrum obtained by the spectroscope cannot be applied to the absorbance image by an actual imaging system. In this study, we corrected the mismatch of spectral information between instruments using direct standardization. A concentration regression model was constructed by machine learning based on the modified absorbance spectrum, and the reaction diffusion phenomenon by the HCl-NaOH aqueous solution flowing through the Y-shaped microfluidic chip was visualized by adapting to the absorbance image.

The near-infrared (NIR) absorption spectra of aqueous acid, base, and salt solutions were analyzed to construct the database of concentration regression models for chemical imaging. The spectra of the solutions from 0.0 mol/L to 3.0 mol/L at room temperature were measured using quartz cells with optical path lengths of 1 mm and 0.1 mm for the wavelength ranges of 1300−1600 nm and 1800−2100 nm, respectively. The spectra and concentrations were used in multivariate analysis using PLS, PCR, and SVR regression models for calibration and concentration predictions. The result of the calibration regression models shows a qualitative relationship between the actual and predicted concentrations. Variable selection techniques such as CARS, UVE, and combined SPA algorithms were also applied to the regression model for important wavelength selection best suited for the NIR imaging. As a result, the database of spectra and regression models of aqueous acids of HBr and HCl, bases of NaOH and KOH, and salts of NaBr, NaCl, KBr, and KCl were obtained.

In order to evaluate ion diffusion, we propose a visualization method of the spatiotemporal distribution of ion concentration using electrical impedance tomography (EIT) . As target cells in this experiment, cell spheroids based on the two types of cell: the wild type (WT) of MRC-5 and the histone type (HT) in which GFPs are expressed. Ion concentration distribution around the cell spheroids is imaged by EIT using our developed multi-electrode sensor implemented on PCB. As a result, the conductivity reflecting ion concentration around the spheroid increased over time in both types. Then, when the average value of the conductivity at each time in the region within 100 μm from the surface of spheroid is calculated, we found that the rate of change in conductivity of HT is larger than that of WT, which indicates that the ion diffusion rate is different between the two cell types.

Droplet collision to the liquid film flow was observed experimentally. Liquid film flow was formed on the acrylic plate. Droplet with black ink was dropped on the liquid film flow. Height of droplet from the liquid film changed from 0mm to 100mm. A high-speed video camera was placed under the acrylic plate to record the adhesion behavior of the droplet. The moving distance of the black ink was measured from the image taken by the high-speed video camera. As a result, it was confirmed that migration velocity of the black ink part become low when the dropping height becomes high. The penetration depth into the liquid film were calculated by the boundary layer flow model. Results showed that the penetration depth reached to the position of several micro-meters from the acrylic bottom plate.

Cleaning phenomena in semiconductor manufacturing is about the nanoparticles being removed out from, or re-adhering to, or returning to the wafer surface. However, the residual nanoparticles from polishing slurry on the wafer are usually inspected only before and after cleaning process, not during wet cleaning process. Therefore, these cleaning phenomena mechanism on the surface have not already clearly known. We have been studying these phenomena by visualizing the nanoparticle motion on a surface in nanoscale wet cleaning process that are duplicated in lab-scale. This report focuses on the flow velocity distribution occurring on a surface that was obtained by duplicating the water flow in a micro fluid cell on a silica glass surface. We found that the flow, which is nearer than few micrometers from the surface being cleaned, has less shear flow velocity. Therefore, there should be some external force or energy, such as PVA brush or cavitation from ultrasonic, to remove residue particles in cleaning process.

Frictional vibration called the stick-slip occurs when two objects contact each other and relatively move. In familiar terms, the chattering vibration of a machine tool is this vibration phenomenon. Stick-slip may lead to a decrease in safety, life span, and work accuracy. Although this phenomenon has been studied for a long time, its mechanism has not been fully understood because frictional behavior is caused by a variety of factors. Therefore, it is necessary to suggest an analytical method that can represent the state of objects and contact surfaces. In this study, we focused on a rubber block, which is the deformation and occurs the stick-slip motion. We proposed a friction model and a deformation model in the DEM for analysis. Particle size were change, and the stick-slip behaviors of the rubber block were analyzed. As a result, it is show that the behavior is similar to the transient vibration that occurs in experiments when the particle size is reduced.

The forming wiring process by utilizing the laser sintering instead of conventional subtractive process, has been gathering attention from the point of view of environmentally friendly as well as simplifying manufacturing process. We have been attempted to form Cu wiring on the liquid crystal polymer substrate with low dielectric constant by one-step laser-sintering with the wavelength of 532 nm. In this study, to form the bulk-like Cu film with high conductivity, we employed two-step laser-sintering of Cu microparticles introducing laser-preheating process. In order to densify copper film, It is crucial to separate removing organic residue in the coated Cu films and sintering process of Cu microparticles. Using Fourier Transform Infrared Spectroscopy, we clarified that Cu film after conventional drying process contains some organic residue which impedes sintering of Cu microparticles. The resulting Cu copper film applied two step sintering exhibited densified structure with Cu grain boundaries molten, and the low specific residence of 11.7 μΩ·cm. Densification of the laser-sintered Cu films results in enhancing the conductivity of the Cu wire.

For the spread of 5G communication technology, the substrate materials with low dielectric constant used for electronic devices to increase the signal transmission speed of electronic equipment. In this research, we selected a silica glass substrate as the substrate material, which is expected to improve the signal transmission speed by 1.5 times than a glass epoxy substrate. We tried to form copper films on a silica glass substrate utilizing laser sintering method, since large environmental load in wet plating process. In this research, a laser sintered Cu films were formed on the CuO base films formed on the silica glass substrate. Laser-sintered Cu films with width of 75 μm and thickness of 10 μm were formed on CuO base films. With increasing of laser power for sintering of Cu microparticles, the line width of Cu films increased, and the thickness of Cu films decreased. However, no conductivity of laser-sintered Cu films was obtained due to poor sintering of Cu microparticles.

The liquid crystal polymer substrates with low dielectric constant have attracted much attention as one of printed circuit board materials. However, it is chemically stable and difficult to form Cu wire on the substrates. We focused on the laser sintering of Cu microparticles for wire manufacturing, the process is a simpler than conventional electroplating. In this study, The Nd:YVO₄ laser with wavelength of 532 nm and a Gaussian-shaped beam was utilized for sintering, and the beam profile and the spot diameter in the x-direction can be controlled by changing the defocus amount of the laser fabrication setup. Since the low-intensity region of the beam profile does not work, the moderated spot diameter effects on line thinning and densification of the laser-sintered Cu films. When the laser beam with spot diameter of 240 μm irradiated to the coating film, the laser-sintered Cu film with width of 212 μm and specific resistance of 20.5 μΩ·cm was formed. In the cross-sectional observation of the laser-sintered films, the bulky copper with metallic luster was observed at the center of the films.