Interstellar Technologies, Inc. has been developing a series of liquid rockets using ethanol/LOX called MOMO. These rockets use graphite nozzle throat inserts for which nozzle erosion, referring to the increase in diameter of the nozzle throat due to the chemical reactions between the combustion gas and the graphite, has become a problem. This study aims to develop a predictive equation for the nozzle erosion rate of liquid rockets using ethanol/LOX. The authors analyzed data from seven long-duration combustion experiments and calculated the nozzle erosion rate. Using the heat transfer coefficient of the nozzle throat, the heat transfer equation at the nozzle throat was solved and the nozzle wall temperature was also estimated. As a result, it was found that the nozzle erosion phenomenon of liquid rockets using ethanol/LOX has a similar trend to that of nozzle erosion in hybrid rockets using HDPE/LOX. A good correlation was obtained by using the nozzle erosion rate prediction equation of Kamps et al., which has chamber pressure, equivalence ratio and nozzle wall temperature as parameters.

Because the demand for soft actuators and soft robots is increasing in space engineering, medical care, and others, the research on dielectric elastomers has been active in recent years. In this study, to develop better performance dielectric elastomer actuators (DEAs), viscoelastic and tensile properties of elastomers were measured using a dynamic viscoelasticity tester and a tabletop tensile tester. It was confirmed that the strain-removed film of commercially available acrylic elastomer has excellent viscoelastic and mechanical properties compared to commercially available materials. Furthermore, circular DEA was fabricated, and their electrodynamic properties and electric field response were evaluated. It was found that the material with the largest deformation as a circular DEA is acrylic DE with strain removed, and it is also superior in terms of both electric field strength and deformation.

Single crystal Ni based superalloys for Gas Turbine blades has an interesting structure that the L12 γ' phase cubes are regularly arranged at equal intervals in the face center cubic γ phase. During the high temperature creep test, the γ' phase of Ni based superalloys has multiple cubes in the transition region. However, the γ' cubes begin to connect with one another in the lateral direction perpendicular to the tensile direction to be rafting structures in the steady state region and the accelerating region. The multi scale simulation methods including the three dimensional phase field method are well-known as simulation methods for phase changes. However, it is convenient to have a simulation method for metallographic changes using various metallographic charts in published papers and data bases, because the published metallographic charts can be utilized for prediction of the behavior between the charts before and after phase transition. Therefore, in this research, Metallographic changes of CMSX-4 which is a single crystal Ni based superalloy in the accelerating region were studied by using metallographic charts of Miura, Kondo and Matsuo's paper via the two dimensional discrete cosine transform (2D-DCT) and the Maximum Entropy Method. As a result, it has been found out that this method could be a promising method to study metallographic changes coming up with the creep rate changes.

Hypervelocity impact (HVI), up to 14,000 m/s, of metallic projectile on Al or Ni multilayer composite structure or monolayer structure are simulated by molecular dynamics (MD) method. The translational kinetic energy of the projectile causes the formation of heat and the deformation of solid bodies. Damage, deformation and phase transformation of the solid bodies are analyzed from the mesoscopic viewpoint. The space distribution of physical quantities in the both structures are visualized by CG movie in collision process.

The equivalent cyclic stress ratio R_EQ followed by elastic-completely plastic yield zone partition type cross-section dimension dependence magnification factor, which is modified to fatigue strength criterion specification, is applied to estimation of plane bending fatigue strength of a smooth bar with rectangular, circular and rhombic cross-section, and rotating bending and torsion fatigue strength of a round smooth bar from an axial load fatigue strength diagram of a smooth specimen. This approach is expected to be effective in elucidating the size effect and its material dependence.

The main issues are as follows;

(1)R_EQ is calculated by using a plastic/elastic section modulus ratio (a shape factor) of elastic-completely plastic smooth specimen Z_Y/Z_E in place of the stress concentration K_t.

(2)Cross-section dimension dependence magnification factor F_S0 is derived as a yield strength criterion specification by means of the coordinate transformation of an equation of a yield zone growth curve, and the magnification factor F_S0^+- is modified to F_S0^kM as the fatigue strength criterion specification by using Schütz parameter M (a coefficient of a proportional term related to mean stress of a linear equation of fatigue strength).

(3)Rotating bending fatigue strength of a round bar specimen is simulated as completely reversed plane-bending fatigue strength of a smooth bar specimen with a cross-section of a pair of the isosceles triangles connected and fixed at the vertices.

This study evaluates the sliding amount at backlash joints on extensible space truss structures and examines the effects on the nonlinear vibration response. Previous study cannot directly evaluate the sliding amount at backlash joints on extensible truss due to the lack of sensors. Therefore, the purpose of this study is to grasp quantitatively the sliding amount at backlash joints and identify its effects on the nonlinearity of the vibration based on the acceleration output at more number of points. Acceleration sensors were attached to suitable points of horizontal and vertical members of the truss, which might move independently due to the existence of the backlash. As a result, it was found that each member was moving independently especially when the amplitude of the vibration was greater. Thus, this method is likely to capture quantitatively the sliding amount at backlash joints. Moreover, a time-frequency analysis of the acceleration data was performed. To this end, the wavelets transform was applied to the acceleration data and the relative acceleration data between the vertical and horizontal members. As a result, it was shown that the amplitude of higher frequency band damped faster for the relative acceleration data than each acceleration data, which captured how long the sliding at backlash continued in pin axis direction during nonlinear free vibration.

Developing 2-dimensional large self-deployable panel structures with higher flatness, we proposed a convex hinge and investigated the folding properties by experimental model. In the experiments, two types of configurations of convex hinge were evaluated in the load testing with the Miura-ori folded panel structures. The result showed the performance of folding properties for convex hinges. Finally, possibility of convex hinges for applying 2-dimensional self-deployable structures were discussed.

In this paper, the geometrical imperfection observed in a lattice structure fabricated by a metal 3D printer was measured using XRM, and the amount of imperfections on the mechanical properties were discussed. There are mainly three types of imperfections (ovalization in the cross-section, offset of the center-axis and radius deviation) in a lattice block. By considering these irregularities on a FE model, the degradation of mechanical properties can be fairly evaluated.

The authors have investigated Active Debris Removal (ADR). We shot a metal harpoon as the capturing system of ADR and evaluated the effect of the penetration behavior experimentally by rotating the harpoon to capture space debris. We dug a groove in the rear of the harpoon to make the harpoon rotate by passing through the air. We also prepared the harpoon without the groove. The effects of the rotation of the harpoon were investigated by comparing the results of the two types of harpoons. We also confirmed the rotation of the harpoon, and rotation speed was measured by using the white line drawn on the rear part of the harpoon. In the experimental results, there was not much difference in the penetration behavior at the oblique angle of 0 and 30 degrees. However, the difference in the penetration behavior was observed at the oblique angle of 45 degrees. If the harpoon slides on the target, the kinetic energy of the harpoon cannot be used efficiently for penetration. However, the gyroscopic effect of the harpoon's rotation allows the kinetic energy to be used efficiently for penetration. We gained insight into the effect of the rotation of the harpoon from these results.

It is difficult to determine experimentally the nanometer level structure of shockwave propagating in solid materials. In present study, molecular dynamics (MD) simulation is performed to clarify quantitatively the atom level structure of shockwave propagating in fcc crystalline Al or Ni in the <100> direction. Simulated metal to metal collision model is similar to the experimental equipment of the split Hopkinson pressure bar which is used for the high strain rate deformation test. The non-closed pack (100) plane of the fcc crystal is the collision plane.

This paper focused on the deformation and stress distribution as the basic mechanical properties of two-dimensional membrane space structures with flexible devices under tensile loads to improve surface flatness as the structural performance of the membrane structures. Finite element analyses of a square membrane with a square device under tensile loads in the diagonal direction using solid elements were performed to examine the stress concentration. Two models as the normal model and the device-inclined model with different configurations for attaching a device were investigated. Numerical results showed that the center of the membrane was deformed on the opposite side of the surface with a device attached in analysis models. The maximum displacement of the center of the membrane and the maximum stress around the device edge in the device-inclined model were smaller than in the normal model and the stress concentration occurred at the corners of the device in the normal model. Moreover, the results for different thicknesses of the device and membrane indicated the maximum deformation occurred when the thicknesses of the device and membrane were almost the same. Finally, the basic mechanical properties have been discussed.

In this study, the mechanical properties of chiral and achiral structures, which are mirror-image isomers, were compared with previous thesis by using FEM. In addition, a new method of equivalent shear modulus was investigated. As an application example, the vibration characteristics were investigated. Specifically, we predicted the natural frequencies due to in-plane vibrations considering the mechanical properties. In addition to the Bernoulli-Euler beam theory of bending vibration, a new method based on the Rayleigh-Ritz method is proposed. The Tetra-chiral structure is not suitable for vibration, while the Anti-chiral structure is suitable for vibration.

In order to develop a highly-sensitive small-scale tactile sensor, piezoresistive effect of graphene nanoribbon was applied to the sensor. It was confirmed that the graphene nanoribbon narrower than about 70 nm showed semiconductive properties and thus, large piezo-resistive constant. The dumbbell shape was applied to the stable junction between metallic graphene and semiconductive graphene. It was easy to form stable ohmic contact between the metallic graphene and metallic electrode. An area-arrayed nanoscale GNR structure with varying width was fabricated for a highly sensitive tactile sensor. Graphene was synthesized inside a copper pocket using a low-pressure chemical vapour deposition (LP-CVD) method. PMMA- assisted wet transfer process was used to transfer graphene grown on the copper to the target substrate. Then, the electrodes were deposited using electron-beam deposition. A four-point bending test was carried out on the sensor to determine the piezo-resistive effect of the DS-GNR. Finally, the gauge factor was determined under the application of various amounts of strain.

It is investigated that the structure of Magnesium (Mg)-based compound containing Fe and graphene (GN) for Mg-based hydrogen storage material, which is one of the most prospective hydrogen storage materials because Mg possesses a larger hydrogen storage capacity (7.6 wt.%). The high dehydrogenation temperature of Magnesium hydride (MgH₂) (approximately 450 ℃) should be reduced for a wide range of applications and one of the solutions would be to compound Fe and/or graphene into Mg due to decreasing the binding energy of hydrogen and Mg. Firstly, we prepared less-defected graphene by Salt-assisted Milling - Liquid Phase Exfoliation method (SM-LPE) method and evaluated the number of layers and the crystallinity with Raman spectroscopy. We estimated the GN consists of a single and/or a few layers and has high crystallinity with few defects. Secondly, we prepared the five different compounds of Mg, Fe, Graphite (Gr), and Graphene (GN) by high-energy ball milling and the different milling time. With regard to the compounds, a large amount of amorphous powder was recovered in all of the compounds to which Gr/GN was only added. In terms of the order of addition of Gr/GN, it was confirmed that the Gr/GN adhered to the Mg surface by being added at later milling, and in particular the GN was distributed throughout the sample as nano-particles.

In this study, a transparent and highly breathable thin-film temperature and humidity sensor was developed as a concept proof for multimodal patchable devices using ion gels. The sensor can detect temperature and humidity selectively by using two types of ionic liquids for sensing layers. Ionic liquids were compatibilized with polymers to form a semi-solid state, called ion gels. Polydimethylsiloxane (PDMS) thin film was used for substrates. Carbon nanotube (CNT) transparent electrodes were fabricated onto PDMS substrate by spray coating method. Ion gel sensing layers were also spray-coated onto CNT electrodes. The fabricated sensor exhibited more than 80 % visible light transmittance and 3.9 times higher water vapor transmission than skin evaporation. LCR meter was used for measuring the impedance of temperature and humidity sensors. As a result, selective detection of temperature and humidity was achieved by using two types of ion gels with different hydrophilicity. These results suggest the easy fabrication of multimodal patchable devices by using various types of ionic liquids.

In this paper, the reactive ion etching (RIE) of a glass with zero coefficient of thermal expansion (CTE) is reported, which can be used for a high Q-factor resonator used in timing resonators and gyroscopes. ZERO CTE glass can be used for a high Q-factor resonator, which is a key element for gyroscopes. SF6 and Xe were selected as etching gases. A thick Ni film was used as an etching mask. Experimental results show that ZERO CTE glass can be patterned by RIE at an etching rate similar to that of quartz glass. Due to the impurities which were used to control the CTE, the etched surface become rough and the sidewall tilted at about 20 degree. The minimum etching width as small as 30 μm could be achieved.

In this study, we investigated the electronic structure and DOS of Ni-Ti-Al Heusler alloys, which have use in research and development as high-temperature structural materials, for high thermoelectromotive force by using first-principles calculations. Based on these analyses, we aim to create and analyze materials with non-stoichiometric compositions and nano- and composite structures in material experiments. The goal is to realize practical high-performance Ni-Ti-Al Heusler alloy thermoelectric materials by searching for materials that exhibit synergistic effects from electronic structure and DOS to nano- and micro-composites on a multiscale and by elucidating the mechanisms.

We analyzed the electronic structure by first-principles calculations and focused on compositions with a small density of states at the Fermi level and an abrupt change in density of states near the Fermi level, and predicted the thermoelectric performance by the Boltz TraP method.

In this study, we built three-dimensional models for the series, parallel composite, and random, off-diagonal and gradient distribution composite. We investigated the thermoelectric characteristics of Ni/TiO_2-x composite thermoelectric materials using Monte-Carlo finite elemental method with the three-dimensional models. In addition, Ni/TiO_2-x composite thermoelectric compacts were prepared and the thermoelectric properties were measured. We also discussed the influence of the composite structure type on thermoelectric properties for enhancing thermoelectric performance.

Rotating bending fatigue tests were performed on thin round bar of SUS304 steel with five levels of ultra-fine grains with an average grain size of 0.9 to 7.1 μm. Since the fatigue limit was higher than the 0.2% yield strength, it was inferred that the austenite phase underwent stress-induced transformation to the martensite phase during the fatigue process. Therefore, X-ray diffraction measurements were performed on the gauge points of specimens, and the changes in the austenite half-value width and the martensite integrated intensity, and changes in the magnetic flux density during the fatigue process were investigated. In addition, the EBSD analysis of the cross section of the run-out specimen was conducted to examine the aspect of transformation. As a result of the EBSD analysis, it was confirmed that the crystals in the surface layer of the specimen with relatively large grain size were refined, and the structure was found to be martensite phase. Since the martensite integrated intensity increased rapidly from 104 cycles, it was presumed that the stress-induced transformation with refinement started at this timing.

SiC micropatterns were fabricated using femtosecond reactive laser sintering under Ar gas injection. First, a Si/C nanoparticle ink was prepared by mixing Si nanoparticles (particle size <100 nm), nanocarbon (particle size <100 nm), ethylene glycol, and polyvinylpyrrolidone. Then, Si/C nanoparticles were sintered by irradiating the focused femtosecond laser pulses to the Si/C nanoparticle film spin-coated on SiO₂ glass substrates. Finally, non-sintered Si/C nanoparticles were removed by rinsing the substrates in ethylene glycol. Compared with the crystallinities of SiC patterns fabricated ambient atmosphere, those of SiC patterns fabricated under Ar injection was improved. These results suggest that SiC micropatterns were sintered reactively under inert atmosphere without significant oxidation.

Chemical biosensors using graphene as a sensing element have been developed for a new generation of highly-sensitive miniature exhaled multi-gas sensors for early detection of various diseases. In this study, carbon nanotubes (CNTs) were synthesized directly on graphene to increase the surface area of the molecular adsorption in order to improve the sensitivity and selectivity of the graphene-based gas sensor. The synthesis of graphene was performed in a low-pressure chemical vapor deposition apparatus on a very pure copper catalyst substrate. The grown graphene was transferred onto a Si/SiO₂ substrate. A CNT layer was also formed directly on the graphene sensor element using a thermochemical vapor deposition method. Stable ohmic contact was observed between the synthesized CNTs and the base graphene layer. It was also confirmed that the sensitivity of the graphene sensor with the CNT layer to gas molecules was improved by about 4 times compared with the conventional graphene sensor.

In order to improve the selectivity, the interaction between graphene and various gas molecules (CO, H₂O, and NH₃) with and without applied tensile strain were calculated by using first-principles calculation. The changes in adsorption energy and charge transfer (including Bader charge analysis and charge density difference) were further investigated by applying 0%-10% uniaxial tensile strain on the graphene surface. It was found that the adsorption behavior of distinct gas molecules on the graphene surface varied linearly and has different trends under the application of tensile strain. Some gas molecules such as CO and NH₃ gradually desorbed, while other gas molecule such as H₂O, on the contrary, adsorb more stably with increasing tensile strain. These findings provide feasibility and guidance for further experiments that strain engineering can be used to improve the selectivity of graphene-based gas sensors for further applications in health monitoring.

In this study, we developed a kinetic-pump integrated microphysiological system (MPS) that supplies nutrients to cultured cells without changing the culture medium, aiming to realize a culture environment in which drug concentration in MPS is continuous for novel pharmacokinetic evaluation. The nutrients dialysis chamber of the MPS is separated into upper and lower compartments by a dialysis membrane, and nutrients are supplied by diffusion due the difference in its concentration. To evaluate the function of the MPS, dialysis function evaluation experiments and cell culture experiments were conducted. The results showed that the difference between the molecular weight of the accumulated dialysis membrane fractions and the molecular weight of the substance in the device enabled permeation and retention of the substance between the dialysis chamber and the cell culture chamber, and that cells in the cell culture chamber could be cultured only by the nutrient supply from the dialysis chamber.

Retrograde flow is the intracellular flow of the cytoskeleton, and it allows for transportation of the structure from the cell edge towards the cell center. It is important to understand the retrograde flow since it is closely related to biological functions, such as contraction forces, metabolisms and turnovers. In this work, we analyze the retrograde flow in immobile cell types given that most of previous studies focused on mobile ones. We obtain fluorescence images of α-actinin, associated with the actin cytoskeleton, in individual A7r5 cells with a fluorescence microscope. We quantified and visualized the retrograde flow in the cells with particle image velocimetry (PIV) and discussed spatial distribution of the intracellular flows. By calculating the divergence of the retrograde flow, we found that the cells have a source of the field not only in the cell periphery but also at the central region of the cells. Since some of the fluid sources are located at the topological defects, we also hypothesize that the topology of cytoskeletons might be related with the cell functions.

We construct a microfluidics-based long-term cell culture system that can perform multiple adaptive laboratory evolution (ALE) experiments in parallel under different conditions. Single E. coli cells were isolated into water droplets in oil (W/O emulsion) containing agarose gel. Micrometric gel balls (GBs) were then extracted from the oil phase and placed in a microfluidic perfusion culture device, which can generate a substrate concentration gradient. The growth of the clonal colonies was monitored under each condition. We tested this GB-based culture device to expand the application of ALE after the gene knockout based on the flux balance analysis (FBA) performed in our previous studies.

The purpose of this study is to diretly observe the formation process of characteristic fatigue dislocation structure in micro-sized nickel (Ni) single crystal specimens with a single slip orientation. Dog-bone shaped specimens with a cross-sectional area of 2 μm×2 μm were prepared by means of a focused ion beam processing system. Although tension-compression cyclic tests under a constant stress amplitude were performed on them, they were interrupted after different cycles (N = 1, 100, 1000 and 3500) and the inside was observed by a UHV-TEM after thinning. In the early stage of the test (N = 1 and 100), dislocations were rapidly multiplied. After N = 1000 where intrusions/extrusions appeared on the specimen surface, the dislocations gathered at the local areas. Then dislocation walls like those observed in a ladder-like structure in PSB was formed after N = 3500 cycle. This implies that vein, which is the important dislocation structure in fatigued bulk material, cannot be formed in micro-sized metals due to the tiny dimension.

As the demand for machine learning and data analysis increases with the global proliferation of online services and AI, its enormous computational load is becoming a challenge. This research aims to realize reservoir computing (RC) technology that enables in-situ sequential analysis of speech and other signal waveforms obtained from microphones at high speed with low computational cost by utilizing the nonlinear characteristics of Micro Electro-Mechanical Systems (MEMS) oscillators. Here, we propose a MEMS-RC that electrically connects multiple oscillators with a modulation mechanism using a thermal expansion actuator, and the strength of the coupled operation can be easily adjusted. we optimized the driving conditions for one and two coupled oscillators and compared their performance and found that the learning performance was improved with the two-coupled oscillators. Furthermore, combinations of coupling strengths that improve the learning performance of the two resonators were plotted on a heat map to identify regions of consistently high performance.

In this study, we evaluated the carrier concentration dependence of phonon and electron mean free paths in single crystal Si. The phonon group velocity was derived using the nanoindentation method, and the thermal conductivity was derived using the laser spot periodic heating method. The phonon mean free path was derived by combining them. In addition, electron mean free paths were calculated, and the carrier concentration dependence on phonon and electron mean free paths were evaluated. As a result, both phonon and electron mean free paths were exhibited in the order of 10^-8 -10^-9 m, and were found to show a similar behavior depending on the carrier concentration.

In a measurement of thermal property, to raise emissivity of sample surface is sometimes important. Blackening of the sample surface is a standard way to raise its emissivity for the measurement by a laser spot periodic heating method and a laser flash method. The blackening brings not only an increase of sensitivity but also an influence on the result of thermal property measurement, and then we should evaluate it in a quantitative way. In this research, thermal diffusivities of the four types of samples whose thickness of blackening layer are different were measured by periodic heating method and laser flash method. The relationship between apparent thermal diffusivity and thickness of blackening layer were obtained. Thicker the blackening layer is, lower the apparent thermal diffusivity is. The tendency of relationship between thickness of blackening layer and apparent thermal diffusivity are same in both of periodic heating method and laser flash method. Interfacial thermal resistance of samples is estimated by the comparison between experimentals and theoretical simulations of laser flash method.

Raman spectroscopy has been used to investigate the stress of resin sheet made from thermotropic liquid crystal polymer. The nominal strain and stress dependencies of the 1730cm^-1 band due to stretching of the ester binding, have been studied in detail and found that a number of Raman bands show shifts with stress following tensile deformation.

Sputtered Al/Ni multilayer film shows self-propagating explosive reaction, which enables us to use the film as a local heat source for instantaneous reactive bonding for semiconductor devices. However, cracks are introduced into reactively alloyed NiAl layer due to its volume shrinkage after the reaction, which decreases the mechanical reliability of the bonded element. In this study, we investigate the B addition effect on Al/Ni multilayers to reduce cracks for reliable die bonding. The cantilever bending test and tensile fracture toughness test are conducted to examine the Young’s modulus, yield strength, tensile strength, and fracture toughness of the reactively NiAl with and without B. The B-NiAl film’s fracture toughness value is 2.82 MPa·m1/2, which is 1.39 times higher than the value for the NiAl without B. Transmission electron microscopy suggests that B segregation at the triple point of crystal grains suppresses the intergranular fracture, which has contributed to improve its toughness.

This paper proposes the nine-point bending test technique for providing out-of-plane deformation with a sintered silver (s-Ag) die attach element for power modules to understand the s-Ag degradation mechanism during thermal shocked test (TST). By comparing NBT with TST, the s-Ag degradation is clarified from the aspect of mechanical and thermal stress. From the scanning acoustic tomography (SAT) image analysis, mean degradation rate was similar between TST and NBT up to 1000 cycles. That was mechanical stress played a significant role for determining the s-Ag die degradation during TST. The deviation value of TST, however, showed 5 times higher than the value in TST. From the cross section scanning electron microscopy image after 1000 cycles, cracking and s-Ag aging coexisted only in TST, leading to destabilize the s-Ag die part degradation.

In this paper, a relationship between a thermal resistivity of solder joint with different compositions and a Cu-Sn intermetallic compounds (IMCs) formed by a heating process is investigated by a periodic heating method. Resulting the periodic heating method, the values of the apparent thermal diffusivity of the specimens including the solder joints ranged 57 ~ 71 mm²/s depending on the elemental composition. The thermal resistivity of the solder joint layers are estimated 2.3 ~ 3.3 × 10^-6 m²K/W by a mixture rule with measured thermal properties. Moreover, a SEM observation found that the difference were attributed to the morphology of the formed IMCs and the elemental composition added to tin.

Micro / Nano electromechanical system (MEMS / NEMS) resonators can achieve high-resonance quality factor (Q-factor), which can be advantageous in applications for ultra-sensitive gas sensing. Q-factor is being considered as an important parameter of such sensing devices, and is enhanced by reducing the dissipation of mechanical energy stored in the resonator arising from various sources including air damping, thermoelastic damping, anchor loss, etc. In this study, anchor loss is investigated because it can emerge as the dominant mechanism of energy dissipation in ultra-high-quality factor resonators operated in high vacuum and low temperature. By numerical analysis via finite element method using perfectly matched layer (PML) technique, several anchor geometries are proposed to reduce anchor loss. Among them, a design with additional mass at the anchor point gives the highest simulated Q-factor. We also fabricated Si micro resonators having 300–500 μm length, 2 μm width and 7.5 μm thickness from silicon-on-insulator wafer. Q-factor of the fabricated micro resonators is evaluated in a vacuum chamber (~1 Pa) and at room temperature by the ring-down method with a digital lock-in-amplifier.

Micro-order particle sorting technology is essential for research applications in the chemical, environmental, and biomedical fields, as well as in various industrial sectors. Many microfluidic devices have been proposed to sort and collect microparticles in the liquid phase. On the other hand, there are not many microfluidic devices for sorting and collecting particles in the gas phase, such as PM2.5 and other dust particles. In our previous study, we successfully developed an electrostatic precipitation technique that uses dielectrophoretic forces to retain microbeads in the gas phase. In this study, we will integrate the dielectrophoresis electrodes into a microfluidic device and apply them as a particulate sorting and selection.

Microbeads flow across the channel. Since the shear force of the fluid depends on the flow velocity, by using a microfluidic device that changes the cross-sectional area of the channel, the shear force of the fluid is varied while crossing multiple electrostatic precipitators so that only particles whose forces are balanced against each other are retained on the electrodes. Theoretically, only microbeads of arbitrary mass and diameter can be retained by controlling the flow velocity and dielectrophoretic force. We are aiming for practical application as a technology that enables the sorting and collection of microbeads.

Droplet-based microfluidics is expected to be used in various fields such as nuclear energy, chemistry, and medicine. However, it has been difficult to produce stable instantaneous coalescence of multiple droplets in the past. In this study, a flow channel with a diamond-shaped expanded chamber was newly designed to achieve instantaneous coalescence of multiple droplets and to adjust the number of coalescing droplets according to the flow rate conditions. Fluid experiments were conducted using PDMS to create a flow channel. As a result, 2-7 droplets coalescence was successfully achieved with high stability. We confirmed that the desired droplet number coalescence could be easily achieved simply by adjusting the flow rate. Furthermore, analysis of the experimental results to investigate the conditions for the number of droplet coalescences revealed that the motion of the droplets perpendicular to the flow direction is a major contributor to the number of coalescences. CFD simulations were also performed to confirm that droplet coalescence also occurs in the analysis.

Photothermal effect is energy conversion process from light to heat due to absorption. Using a focused laser beam, the photothermal effect of working fluid can be used to produce a localized heat spot in microfluidic devices. The locally-heated fluid induces both thermal convection and thermophoresis: The former is the motion of fluid due to a buoyancy force and the latter is the motion of dispersed particles along the temperature gradient of the fluid. In this research, the competition between these two effects is experimentally investigated by using a microgap fluidic channel with a variable gap size. Thermal convection is more affected by the channel confinement and becomes weaker as the gap size decreases. Therefore, the thermal-convection-dominant state is observed when the gap size is above a threshold. However, when the gap size is below the threshold, the thermophoresis-dominant-state appears. This experiment demonstrates a switching method between these two competing states by simply changing a channel dimension.

Recently, micro- and nanofluidics devices such as MEMS/NEMS and μ-TAS have attracted much attention. However, several unknowns have been remained in micro- and nanoscale transport phenomena unlike microscopic scale. In order to deepen understanding of such micro- and nanoscale phenomena, it is essential to develop a novel technique to measuer the small spaces. In this study, a localized and direct measurement method of electric fields is established by using a test section with a charcteristic length of 1 mm and a glass microelectrode. Using a KCl standard solution ranging from 0.56 to 100 mmol/L as a sample, the conductivity is successfully evaluated with a measurement error of less than 15%.

It has been reported that a system of spring-masses connected in the form of a ladder has a flat-band dispersion relation in which the eigenfrequency degenerates for certain translational degrees of freedom by appropriately selecting the spring constants and masses of the mass points. In this study, we show that, by considering the nonlinearity of the spring in this structure, it is possible to construct a mobile localized vibration mode which is stable and robust to perturbations.

This paper presents a numerical analysis of bulk-type all-solid-state lithium-ion batteries. The electrochemical modeling for analyzing all-solid-state batteries (ASSBs) is described, in which a single-ion conducting electrolyte theory is presented and coupled with the pseudo-two-dimensional (P₂D) battery model used for lithium intercalation reactions in the porous electrodes. The benchmark study for an all-solid-state cell of Li/Li_9.6P₃S₁₂/LiNbO₃-coated LiCoO₂ is performed using COMSOL Multiphysics^®. The calculated charge-discharge curves agree well with the available experimental data. The modeling for the lithium diffusion coefficient in electrode active material particles, which is represented as a function of lithium stoichiometry, is also examined.

With fossil fuel prices soaring due to the Ukraine crisis, countries must not only achieve energy self-sufficiency in the future, but also curb CO₂ emissions to prevent global warming. In order to achieve both of these goals, our laboratory has been developing a High Functional Direct Carbon Fuel Cell (HF-DCFC) composed of a molten salt gasification and a Tubular Molten Carbonate Fuel Cell. HF-DCFC can generate electricity directly using various organic wastes as fuel, but the previous study was elucidated that its cell performance is greatly affected by the fuel type. In this study, the gasification characteristics of polyethylene (PE), wood pellets (WP), and onion peels (ONION) were investigated for the installation of HF-DCFCs in each community as a waste treatment generator. As a result, the highest CO and H₂ production as fuel for HF-DCFC occurred with WP under 70(25CO₂/75N₂)/30H₂O atmosphere. PE produced hardly CO and H₂ productions, but high sulfide emissions. ONION gasification produces CO and H₂ second only to WP with little CH₄ production, but gasification characteristics were greatly enhanced when ONION was wrapped in PE and fed. Moreover, in all fuels, the addition of air inhibits the formation of fuel gas through partial oxidation reactions and reduces gasification efficiency but increases energy efficiency because the oxidation reactions raise the temperature of the molten salt.

To improve the H₂ yield and thermal efficiency for the biogas dry reforming process, this study has been conducted the experimental investigation using a membrane reactor by changing reaction temperature, differential pressure between reaction chamber and sweep chamber, and molar ratio of inflow gas with and without a sweep gas. In particular, we have focused on the effect of molar ratio of inflow gas. The concentrations of reactant and product gases were measured by gas chromatography to clarify the effects of the above operation conditions on the reaction characteristics. We have evaluated the conversion of the reacted gases (CH₄ and CO₂), H₂ yield, H₂ permeability, and thermal efficiency. As a result, the largest H₂ was produced at the molar ratio of 1.5:1 irrespective of reaction temperature, and the differential pressure between reaction chamber and sweep chamber with and without a sweep gas. It was observed that the concentration of CO is larger than that of H₂ irrespective of reaction temperature, differential pressure between reaction chamber and sweep chamber, and molar ratio of inflow gas with and without a sweep gas. Under the experimental conditions in this study, the H₂ separation rate which is enhanced by the differential pressure and sweep gas exceeded the kinetic rate of H₂ production, resulting in a low concentration of produced H₂. Therefore, it is necessary to clarify the optimum conditions where the H₂ separation rate matches the kinetic rate of H₂ production.

This study has clarified mass and heat transfer phenomena as well as power generation performance by numerical simulation using a 3D model under high temperature operation conditions of 90 °C and 100 °C, which are the target operation temperatures for the application usage such as Ene-farm and FCV, respectively during the period from 2020 to 2030 according to NEDO roadmap 2017. Distributions of H₂, O₂, H₂O, current density and temperature on the interface between polymer electrolyte membrane (PEM) and catalyst layer (CL) were calculated by changing the relative humidity of inflow gas and operation temperature. The temperature distribution on the interface between PEM and CL at the cathode calculated by this study was compared with that calculated by 1D multi-plate heat transfer model developed by the authors.

A popularization of Polymer Electrolyte Fuel Cell (PEFC) is necessary to realize ahydorgensociety. However, the manufacturing cost is still expensive, and it is required to reduce the manufacturing cost for further spread. In our laboratory, we have been developing 3D catalyst layers using ink-jet printers (IJP) and self-water management catalyst layers (SWMC) by adding carbon grains in order to reduce the amount of platinum catalysts used while maintaining the power generation performance. The IJP method can form a catalyst layer with a three-dimensional structure, but its disadvantage is that it cannot coat our proposed SWMC, due to the long coating time and small nozzle diameter. Therefore, in this study, we investigated the possibility of producing SWMC by the spray coating method in order to shorten the coating time and enable the application of carbon additives. As a result, Although it was confirmed that the spray coating method was able to disperse and apply the added carbon grains, the polarization resistance was worse than that of the IJP method. The polarization resistance of the catalyst layer with spherical graphite was hardly different with that of the standard catalyst layer, consequently it was confirmed its effectivness. On the other hand, graphite rubbish increased polarization resistance drastically by damaging the polymer membrane during the spray application process, inducing cross leakage.

The aim of this study is to detect defects in polymer electrolyte fuel cells (PEFCs) easily and instantly by a noninvasive method. The power generation state of the PEFC was diagnosed contactlessly, by measuring the magnetic field formed around the PEFC during power generation. In this study, we applied sparse modeling theory as an inverse problem method to estimate the current distribution in the electrode from the magnetic field, and verified the effectiveness of defect detection inside the fuel cell. First, we verified with in experiments using a fuel cell that simulated the current flow inside the fuel cell, and then in experiments using a 1-cell stack containing one layer of MEA (Membrane Electrode Assembly) with a power generation area of 50 mm x 50 mm. As a result, we succeeded in accurately detecting the defect position in the center of the electrode, which was previously impossible.

A popularization of Polymer Electrolyte Fuel Cell (PEFC) is expected as a clean energy. However, the manufacturing cost is still expensive, and it is required to reduce the manufacturing cost for further spread. The cost of platinum catalyst in the catalyst layer of the membrane electrode assembly (MEA) accounts about 50% of the total manufacturing cost. Therefore, the reduction of the amount of platinum catalyst is necessary for further popularization of PEFC. Generally, because the catalyst layer (CL) of MEAs is manufactured by the doctor blade method, this method has some problems such as poor dispersion of Pt catalyst in the CL and difficulty in controlling the membrane thickness. Although our laboratory proposes the application of inkjet coating method to the manufacturing process of CL to solve these problems, it is clarified that this method has some problems such as the crack of catalyst layer surface and increase of the ohmic resistance. Therefore, we were clarified points to be considered in the inkjet coating method by evaluating two drawing methods by ink jet printer such as a continuous (Inkjet-A) and an intermittent coating methods (Inkjet-B). As a result, although in the continuous coating method, ink droplets agglomerate, which contributes to the separation of the platinum catalyst and ionomer and makes it worsens ohmic and diffusion resistances, in the intermittent coating method, the ink droplets dried on their own and did not agglomerate, and the degree of separation between the platinum catalyst and ionomer was low. In the inkjet coating method, drawing the applied ink droplets so that they dry alone contributes to improved cell performance.

One of the efforts to help able-bodied people deepen their understanding of disabilities is to experience sports for the physically challenged. Previous studies (Yasui, 2004; Yoshioka & Uchida, 2007) have reported that people's perceptions of people with disabilities and sports for people with disabilities change positively through the experience. Furthermore, it has been pointed out that experiences that remind people with disabilities of their daily lives are necessary to lead to changes in awareness and behavior for solving everyday problems (Nakamura, 2020). Therefore, in this study, we conducted an experience of sports for the visually impaired for university students by combining an experience of a competition for the visually impaired and pair work to think about solutions to the problems of people with disabilities. Before and after the experience, a questionnaire survey was conducted on the awareness of people with disabilities and sports for people with disabilities, as well as on how people perceive disabilities, with the aim of verifying the effectiveness of the sports experience for people with disabilities. The results showed that participation in the experience positively changed the target group's awareness of people with disabilities and sports for people with disabilities. In addition, there was a trend toward an increase in responses from the perspective of the "social model," which views disability as something that occurs when people face various barriers in society.

It is illustrated in general that the decision-making in conceptual design is highly dependent on the designer's aesthetic sense. However, even in a subjective phase, objective aspects such as mechanical rationality are implicitly or explicitly considered, and these two perspectives are inseparable. A concept of mechanical Kansei defined as “the capability to evaluate and judge impressions in terms of unconscious, intuitive, and integrative information in mechanics,” has been proposed to elucidate how this capability is utilized for design. In this article, we focus on the capability to unconsciously recall the force flow inside a structure; and take the topology-optimized structures as the representation of such force flow. Through learning the structural shapes with a variational autoencoder (VAE), dimensionality compression from the large design variable space to the lower dimensional latent variable space is performed. As a result, it was shown that the two-dimensional latent space reflected the geometric positions of randomly located supports on the design domain. The obtained mappings from the structural conditions to the representation of force flow in structure within the encoder and decoder of VAE can help to understand the mechanical Kansei.

This study focused on physical ability and related factors that influence older adults' intention toward family caregiving and conducted a questionnaire survey on age, health status, and self-efficacy. The survey was administered to older Japanese and Chinese adults and analyzed the relationship between their intention for family caregiving and factors related to physical ability. The results of the analysis were compared between Japan and China. Through comparison of the analysis results, the influence of factors related to the physical aspects of the older adults on their family caregiving intentions and the differences in the factors that determine the family caregiving intentions of the older adults in Japan and China were clarified.

This study conducted an internet survey to clarify the influences of competitive situation skills, group cohesiveness, and social support on life satisfaction among Japanese and Chinese athletes. Multiple regression analysis was conducted using life satisfaction scores obtained from the survey as the dependent variable and scores on other psychological factors as the independent variable. The results of the analysis revealed the psychological factors of Japanese and Chinese athletes that influence life satisfaction. The differences in associations found between these factors were compared and discussed in light of the athletic environment in Japan and China.