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The focused acoustic field formed under the water surface raised by ultrasound exposure was numerically investigated to elucidate the relationship with the surface rising prior to ultrasonic atomization. The effect of surface tension was newly added to the computational scheme constructed in the previous paper (Orisaki and Kajishima, 2022) and the direct numerical simulation based on compressible fluid dynamics was conducted. The water surface above the sound source rises. When the risen surface shape changes into a dome due to the effect of surface tension, the acoustic antinode with strong focusing appears inside the dome and the water surface begins to rise rapidly. In case of the insufficient sound source pressure, the gentle risen surface is kept, and acoustic peak spots remain deep due to the small curvature of the surface. These results suggest that the dome formation increases the acoustic pressure amplitude at the dome center and promotes acoustic cavitation there. On the dome surface, the kinetic energy density with the phase opposite to acoustic pressure increases, which causes the increase in the acoustic radiation pressure.

To analyze self-lubricating mechanism of copper-based graphite composites, the discrete element method (DEM) was used to study motion law of graphite particles of copper-based graphite composite/45 steel during friction. The research results show the film-forming particle layer was formed on the composite surface after a period of friction, which maintained dynamic balance depends on continuous supply of graphite in the composite. At different position, the trajectory of graphite particles is different, but the motion tendency of the graphite is the same, that is, the graphite x movement direction is consistent with the sliding direction of 45 steel, the graphite y movement direction is from the inside of the composite to the friction interface, and the motion displacement in y direction is greater than that in x direction. The load and sliding speed have an important influence on the motion law of graphite. Load or speed change the trajectory of graphite particles. However, the load and speed did not change the movement trend of graphite particles, which were consistent with motion trend at different position.

Transient behaviors of molecular orientation field of nematic liquid crystal (4-n-4’-octylcyanobiphenyl) under shear flows between concentric cylinders have been numerically investigated using the Leslie-Ericksen continuum theory in which the molecular orientation is represented with a unit vector, called the director. As well as the rotation speed of an inner cylinder, the director anchoring conditions at the inner and outer cylinders are chosen as simulation parameters to obtain four different cases of director initial profiles, which are homeotropic, hybrid, planar, and twist cases. After the imposition of the shear flow, the director start rotating within the shear plane, increasing the curvature energy of the director field. When the energy exceeds a certain critical value, the director start escaping from the shear plane, called the out-of-plane behavior. Because the escaping direction (i.e., either +z or -z directions) is the stochastic choice, the director field is randomly separated into the positive and negative out-of-plane regions. Then, the spatially distributed two out-of-plane regions are transformed into line defect structures. The spatial patterns of the out-of-plane regions and the line defect structures strongly depends on the director anchoring conditions, and no patterns are found for the twist case. The evolutions of torques of the inner cylinder is also estimated from the simulation results for four cases, and the oscillatory behavior of the torque is found for the homeotropic case.

In this paper, a novel dynamical decoupled design of a two-dof differential belt-driven parallel robot is proposed. Equation of motion of the robot, including the inside mechanical properties of pulleys and sliders, are derived by the symbolic multibody dynamics system (MBD) analysis. First, the constraint of a mobile idle pulley and belt are derived, which has not been dealt with in previous studies of general symbolic MBD. A method for overcoming the over-constraints of the closed belt is proposed. The symbolic MBD model of the robot by the differential algebraic equation is established using Mathematica, thus deriving the kinematics and forward dynamics equation of the robot in a symbolic manner. Next, as an upstream mechanism design of the differential belt drive robot, that the off-diagonal terms of the generalized inertial matrix and the generalized viscous matrix of the equation of motion are set to zero by giving additional inertia, and additional viscosity is derived, that enable a dynamic non-interference design for the differential belt drive robot. Using Simscape Multibody, which is one of the general-purpose Numerical MBD software, an extended package of MATLAB/Simulink, a numerical model with mechanical parameter values such as mass, the moment of inertia, and viscosity coefficient assuming an actual mechanism is constructed. The feasibility of the quantity of the added mass and the added viscosity is discussed using a mechanical model assuming an actual machine. The effectiveness of the proposed decoupled design were confirmed by numerical simulations using Simscape Multibody.

We propose a method for solving differential equations implicitly using iterative calculations in spreadsheet software. This method uses difference equations by discretizing the coordinates of the independent variables with cells of spreadsheet for analysis. Thus, the equations are embedded in the cells performing substitution of grid point. In addition, the embedded equations are solved by Newton’s method, and the iterative function of the spreadsheet software is used in the calculation. This method can be applied even when the differential equation is discretized by an implicit solution method. Therefore, it can be applied to ordinary and partial differential equations of different types. The advantages of discretization using the implicit method (high computational accuracy, large time increments) are also presented in this paper. The analysis procedure is almost the same regardless of the type of equation. In this paper, as an example, a simple differential equation was analyzed using Microsoft Excel, a typical spreadsheet software, to illustrate the method. The results are also shown by the analysis of the gas lubrication equation.

Conventionally, repeated experiments by trial and error have been used to improve the printing quality of continuous-type inkjet printers. This is because the trajectories of the ink droplets are affected by external forces such as air drag and Coulomb force and thus their analysis is difficult. In this study, a simulation technique to predict the trajectories of ink droplets, the Kriging model, and a multi-objective genetic algorithm were combined to develop an optimization system which determines a droplet charging pattern with better printing results. To enable parallel evaluation of the printing results with an arbitrary charging pattern, the simulation technique was developed based on OpenFOAM, which is an open-source software for computational fluid dynamics. A multi-objective optimization problem was defined by design variables which control the ink droplet charging pattern and by two objective functions which quantitatively evaluate printing quality from simulation results. The Kriging model was used to calculate the expected improvement of the two objective functions and to maximize this improvement by the multi-objective genetic algorithm (MOGA). The developed optimization system was applied to the digit “9” expressed by a 5×5 dot matrix. As a result, the expected improvement-based (EI-based) Bayesian optimization could find the solution which dominates most of the solutions obtained by the MOGA. Additionally, reaching this solution required only 1/7 of the number of simulations required by the MOGA optimization. The obtained solution was used for an experiment on an actual continuous-type inkjet printer and the quality of the printing results was evaluated. It was confirmed that the printing quality provided by the solution obtained by EI-based Bayesian optimization was sufficiently high, and the usefulness of the developed optimization system was demonstrated.

Gas atomization, in which high-pressure gas jet impinges on molten metal stream from the melt tube to atomize it, is a popular method of producing fine metal powders. In this study, we focused on a swirling flow of the injection gas as a factor affecting the produced powder. Computational analyses and experiments were carried out to investigate the effect of the swirling gas flow on the atomization process. First, a single-phase flow analysis was performed considering only the injection gas. The simulated aspiration pressure agreed well with the experimental results. The behavior of the aspiration pressure against the gas injection pressure depended on the presence of the swirling flow. The simulation results clarified that the aspiration pressure was decreased by backflow into the melt tube in the case of the non-swirl nozzle. The backflow was caused by a vortex just below the melt tube tip, which was generated by the injected gas. On the other hand, in case of the swirl nozzle, the swirling flow decreased the pressure at the center of gas flow and inside the melt tube, which caused a high and stable aspiration pressure. Next, the effect of the swirling flow on the melt behavior and particle atomization was investigated numerically. A low-velocity region was generated at the center of the gas flow as a result of the mass loading of the melt, which was larger in the swirl nozzle. Consequently, the particles in the swirl nozzle were coarser than those in the non-swirl nozzle because some of the particles flying in the low-velocity region could not be atomized enough. Finally, metal powders were produced using a gas atomization plant, and the powder sizes and the surface images were compared. The powder size distribution showed that the non-swirl nozzle produced finer powders than the swirl nozzle did, as in the simulation results.

Spatiotemporal local changes have been extracted for evaluating physiological phenomena by an image reconstruction algorithm of electrical impedance tomography (EIT) using sparse Bayesian learning (SBL). The proposed method identifies a region of interest (ROI) by a priori information on conductivity distribution σ of each biological tissue and automatically learns block-sparsity and temporal-correlation in the identified ROI in the form of blocked column vector (BCV). Two types of numerical simulations are conducted to model lymphedema (LE) and venous edema (VE) that cause spatiotemporal local changes in σ of subcutaneous tissue fluids in human calf phantom which consists of three parts: great saphenous vein (GSV) as ROI and subcutaneous adipose tissue (SAT) and muscle as background. From the results, spatiotemporal local changes in σ are clearly extracted only near GSV by the proposed method even in a field where the time-varying σ in the background is large. Furthermore, the accuracy of the proposed method is evaluated under the variant conditions of conductivity ratios of SAT and muscle relative to GSV, i.e., ρGSV/SAT and ρGSV/muscle, respectively, and area ratio accuracy ARAGSV is the highest in the case where ρGSV/SAT = ρGSV/muscle, which achieves ARAGSV = 2.241 regardless of the values of ρGSV/SAT and ρGSV/muscle.

When an underwater ultrasonic wave is emitted toward an air-water interface, the water surface rises and droplets are generated from the formed fountain. The rising process of water surface was numerically investigated for better understanding the mechanism of ultrasonic fountain prior to the atomization. To analyze the water surface rising that occurs in a very short time, it is necessary to simulate the rapid increase of acoustic radiation pressure and the rapid development of acoustic streaming. Therefore, the direct numerical simulation based on compressible fluid dynamics was carried out. The water surface rising as observed in the formation process of ultrasonic fountain was successfully reproduced. In the region between sound source and water surface, standing wave is established and acoustic kinetic energy density increases significantly while water surface rises with acceleration. The kinetic energy density is associated with the acoustic radiation pressure acted on free surface based on the theory of Yosioka-Kawasima (1955). After the rising speed becomes to be constant, the standing wave fades and the kinetic energy density decreases. These results suggest that the acoustic radiation pressure acted on water surface increases significantly due to temporary resonance and water surface rises rapidly. By drawing a fluid due to rapid rising of water surface, acoustic streaming is induced toward the risen region.

The thermal shrinkage technique, which uses shrinkage strain and shrinkage zone to calculate welding distortion, is expected as a simple simulation to predict the welding distortion of large weld structures. In previous studies, parametric study was performed for bead-on-plate welding and optimum input data settings was clarified, which were the shrinkage strain of −0.012 and a shrinkage zone in which the maximum temperature reached 500°C or more for structural steel. In this research, the thermal shrinkage technique with established input data settings was applied to a construction machinery structure to validate whether the input data settings obtained in the previous study for test specimens is applicable to large weld structures. The analytical model is a construction machinery structure with dimensions of 3.9 m in length, 2.7 m in width, and 0.9 m in height, and has a 40-pass fillet welded joint. The welding distortion analysis using thermal shrinkage technique was conducted with the optimum input data settings. Thermal elastic-plastic analysis considering moving heat source was also performed to compare the numerical results by the thermal shrinkage technique and thermal elastic-plastic analysis. Numerical results revealed that the displacement distribution after 40-pass welding of the construction machinery structure obtained by the thermal shrinkage technique was in good agreement with that obtained by thermal elastic-plastic analysis. A more detailed evaluation showed that the displacement in each welding pass obtained by the thermal shrinkage technique accurately reproduced that obtained by thermal elastic-plastic analysis. The calculation time of the thermal shrinkage technique was 1/7 for the construction machinery compared with thermal elastic-plastic analysis, which clarified that calculation time could be shortened. Our results show that the thermal shrinkage technique with optimum input data settings could be applicable to large weld structures to predict welding distortion.

A micro-machined thermal flow sensor called “Flow Vector Sensor (FVS)” can measure an airflow speed and its direction simultaneously. The FVS is extremely small, and hence it does not disturb flowfields around the sensor. In addition, since a response time of the FVS is very short, the FVS can measure unsteady flows. Therefore, the FVS is expected to be applied to flowfields over various objects such as automobiles. However, when the airflow speed is high, the sensitivity of the prototype of the FVS tends to be lower. In this study, we numerically examine heat transfer from the FVS to the airflow, in order to improve the sensitivity of the FVS in a high-speed airflow. First, we investigate the heat balance between the FVS and surroundings, in order to identify the cause of the lower sensitivity of the FVS. The heat transfer between the FVS and airflows is found to affect the sensitivity of the FVS, especially in the high-speed airflow. Second, we examine the effect of the size of the FVS, in order to discuss the design philosophy of the FVS. The heat transfer from the FVS to airflows is found to decrease with decreasing the size. Consequently, the small size of the FVS can improve the sensitivity of the FVS. These results should provide new insights into the design philosophy of a high performance FVS.

Nickel-based superalloys also have super high strength at high temperatures, which are typically difficult to be processed. As the material of hydraulic parts, aircraft engines, and downhole intelligent tools, it has the characteristics of large cutting deformation, severe work hardening, and low thermal conductivity in deep hole machining, which will lead to the problem of poor straightness of the deep hole. In order to solve the problem of poor straightness of the deep hole in machining nickel-based superalloys, a three-dimensional finite element model of BTA deep hole drilling based on thermal-mechanical coupling is established, and the influence of different blade angles, rotation speeds, and feed rates on drilling force is calculated. The prediction model of drilling force is obtained based on the response surface regression analysis method, and the multi-objective optimization of blade angle, rotation speed, and feed rate are carried out by using the random direction search method. The BTA deep hole drilling experiments are carried out by using the optimized tool and process parameters, and the effects of different process parameters on the straightness of the deep hole of nickel-based superalloys are analyzed. The results of the research show that: Different rotation speeds and feed rates will lead to different degrees of strain hardening and thermal softening. This will lead to a significant difference in the value of the drilling force on the tool. The straightness deviation of the deep hole in nickel-based superalloys can be controlled by optimizing the tool structure and process parameters. The research work in this paper can provide a basis for the structural design of the BTA tool and optimization of process parameters.

This study proposed a simple configuration for a Variable Injection Direction (VID) nozzle for a diesel engine, which can change a direction of fuel injection according to the needle lift amount. Differently from a conventional one, the VID nozzle has a needle tip partly cylindrically shaped, and a divergent-shaped hole-end. The geometry enables to control internal nozzle flow. The needle tip increases the angle of the flow direction to a hole inlet with respect to an axis of nozzle hole at small needle lift, while it decreases the angle at large needle lift. The divergent-shaped hole-end allows for those direction change of injection. The internal nozzle flow was numerically simulated for exploring the nozzle geometry in detail, using the computational fluid dynamics (CFD). Also, for its validation, an eight-times enlarged nozzle was developed and water was injected. The observation was conducted using a high speed video camera. The CFD results showed good agreement with the measurements regarding not only the injection direction but also the needle lift amount when the injection direction switches. The investigations confirmed that the injection direction can be changed within one injection and a magnitude of injection angle is controllable by the nozzle geometry.

Fatigue strength of resistance spot welded high-strength steels does not improve with increasing base metal strength. Therefore, cold-working method and tempering treatment have been proposed as methods for improving fatigue strength. These methods control residual stress, hardness, and both of them to increase fatigue strength. However, it is difficult to say that the effects of hardness and residual stress on the fatigue strength of resistance spot welded joints have been clarified. In this study, to clarify the effects of hardness and residual stress on fatigue strength, these factors were controlled independently by using cold-working method and tempering treatment. As a result, the fatigue life was improved in the joints to which compressive residual stress was applied by cold-working. On the other hand, the fatigue life decreased with the joint where the press load increased and the hardness increased. From these results, it was clarified that the compressive residual stress is a factor for improving the fatigue strength and the increase in hardness is a factor for decreasing the fatigue strength in the resistance spot welded joint.

Functionally graded material (FGM) is an advanced class of composite material. In FGM, the volume fraction of each constituent can be tailor-made across the thickness for desired applications. In this paper, the analytical solution and numerical simulation of free vibration and transient heat conduction problem in a functionally graded pipe are considered. 3D elasticity theory is adopted for considering the thickness effect in the natural frequency derivation. For solving the transient heat conduction problem in FG pipe, the extended shifting variable method is used. A multi layer model is considered to numerically simulate the vibration and transient heat conduction behavior of FG pipe using standard finite element method package. Results obtained from both analytical solution and numerical simulations are compared for the free vibration and transient heat conduction. The 8- and 16- layer models show the higher accuracy for simulating FG pipe. For 16-layer model, the difference in natural frequency between numerical results and analytical solution is under 0.18%. The transient temperature distribution at specific position of the FG pipe is obtained from transient heat conduction study for various FG power law indices. The free vibration and transient temperature distribution of the FG pipe will help to tailor the FG pipe by adjusting the graded ways for specific application.

The purpose of this paper is to clarify the effects of operation of braking devices by sliding friction against rails (rail brake) on the dynamic characteristics of gantry cranes for container handling after runaway caused by unexpected wind gust by a numerical analysis and to obtain the scientific knowledge which serves to develop the technology for safe stopping. Dynamic characteristics of the crane were calculated by the dynamic numerical simulation analysis using FEM. The crane was modeled by three-dimensional beam elements. The interaction forces that define the resistance characteristics of the crane runaway generated at the contact part between wheels of the traveling system and the rails were modeled. And the interaction forces at the contact part between the rail brakes and the rails were also modeled. For the wind gust that becomes runaway driving source, the wind direction, the velocity distribution in the vertical direction and the time change of the wind velocity were modeled. The load that the crane receives by the wind was calculated based on the ISO standard of the wind load assessment of cranes. In the analysis conditions of this paper, the runaway of the whole crane started when the driving wheels of the land side became slide state after those of the sea side became slide state. The dynamic characteristics through the stop of the crane after the operation of the rail brakes concerning cases of varying rail brake operation characteristics were analyzed and considered. The operating characteristics were defined by the time increase rate of the pressing load of the brake shoe, dPB/dt, the maximum value of it, PBmax, and the timing that the operation starts. The crane reached the stop after the runaway velocity decreased with the swing of the rail longitudinal direction of the crane structural system which consists mainly of the legs, the boom and the girder. When the acceleration of the upper part of the crane structural system increases by the rail brake operation, the generated inertial force reached the level that should be considered in checking of the structural safety. Finally, the relationship between the braking distance as an evaluation index of braking performance of the rail brake and the braking operation characteristics was presented and discussed.

In recent years, PMVs (Personal Mobility Vehicles) have been attracting attention as a new means of transportation. We focus on the three-wheeled PMV which has two front-wheel and one rear-caster. They are environmentally friendly without exhausting harmful gases. These vehicle bodies are relatively smaller than cars, so they have a high affinity for pedestrian space. However, depending on the specifications of the vehicle, there is a possibility that wheel lifts during turning because the weight of the vehicle is low. In this study, we proposed the model of the three-wheeled PMV with two front-wheel and one rear-caster. We discussed the validity of the modeling by comparing the numerical simulation and the experiments. In terms of the driving force of the front wheels, the modeling was generally valid when the velocity of the vehicle is low and the turning radius is large. However, in the opposite case, the centrifugal force of the driver during the turning becomes larger and the moment around the front wheels axle center point is generated. Then it is expected that more detailed analysis will be possible by considering the relationship between the centrifugal force received by the driver and the driving force of the motor in consideration of the driver’s behavior. From the parametric study, it was found that the normal forces of the wheels greatly changed depending on the riding position of the driver. The area of the risk of falling was shown.

The backward-facing step channel flow in which the Reynolds number is 1080 is calculated to investigate the control effect by a DBD plasma actuator which is activated with continuous drive or burst modulation. The plasma actuator is located on the edge of the backward-facing step. The conditions for the actuator are 3, 5, 8, and 10 m/s of the surface velocity and 50, 100, 150, and 200 Hz of the burst frequency. When the actuator is activated with the continuous drive, the more the reattachment point moves upstream, the more the induced flow by the actuator is strong. When the burst modulation for the actuator is used, the smaller burst frequency makes the reattachment point move further upstream generally. The reattachment point could travel upstream if a huge vortex has a negative vorticity is generated by merging two vortices near the step. This is because that the huge vortex flows downward with the mainstream flow, on the other hands, if this combining two vortices is not appeared, the reattachment point is little changed. In addition, the mechanism for moving upstream for the reattachment point by the actuator is different for using the continuous drive or the burst modulation. In the continuous drive, the strong enough induced flow by the actuator becomes unstable near the step and flows downward with the mainstream flow, but in the burst modulation, the merged vortex from the mainstream flow appears near the step because a certain period by the burst modulation is introduced in the mainstream flow.

Forging is one of the important manufacturing technologies to produce various mechanical components with high productivity. Recently, servo press that can control the back-pressure and the slide motion during the forging has attracted attention for high product quality without losing productivity. However, the back-pressure or the slide motion that affects the product quality and the productivity is completely determined by a trial-and-error method, and the determination is a crucial issue in forging using servo press. In this paper, a small product is selected as the case study, and both the back-pressure profile and the slide motion in cold forging are optimized. Numerical simulation using DEFORM3D is so intensive that sequential approximate optimization using radial basis function network is adopted to determine them. Based on the numerical result, the experiment using servo press (H1F200-2, Komatsu Industries, Corp.) is conducted. Through the numerical and experimental result, the validity of the proposed approach is examined.

An effective method for handling turbulent fluctuations in temperature and in partial pressure of infrared-active gas is proposed in order to make a fairly accurate simulation within feasible calculation load in relation to radiative heat transfer in the large-scale hydrocarbon flame formed in industrial furnaces. As for the case of large-scale turbulent hydrogen flame in industrial furnace, an effective method for handling turbulent fluctuations has been proposed and verified in our previous papers. And yet, it’s applicability to large-scale turbulent hydrocarbon flames has not been confirmed. In this paper, the abovementioned method is examined as to the applicability to hydrocarbon flames, and then, an improved method is proposed. In regard to the method proposed in our previous papers to reduce the enormous calculation load contingent on detailed non-gray analysis like line-by-line analysis, it’s validity is easily confirmed not only for hydrogen flames but also for hydrocarbon flames. On the other hand, the method proposed in our previous paper for reducing the calculation load required for tracing turbulent fluctuation in temperature in great detail cannot give satisfactory results in relation to the large-scale hydrocarbon flame. So, in this paper, major attention is concentrated on the improvement of our method for reducing the calculation load associated with detailed trace of turbulent fluctuation. The assumption that temperature fluctuations of arbitrary two positions are independent from each other and the treatment of energy radiation associated with turbulent fluctuation are maintained also for hydrocarbon flames. In contrast, the treatment of fluctuating absorption is changed from the case of hydrogen flames. While the temporal mean amount of absorption is evaluated using the absorption coefficient at temporal mean temperature in the case of hydrogen flames, such value is evaluated using the temporal mean value of instantaneous absorptance. Validity of the improved method is examined on a model optical path imaging the typical course of radiative energy in large-scale industrial furnaces fueled by propane. It is indicated by examination that the error caused by improved method is satisfactorily smaller than that caused by entire disregard of turbulent fluctuation of temperature and gas composition. Moreover, this improvement related to the treatment of turbulent fluctuation is satisfactorily valid even if coupled with our efficient method for treating complicated spectrum of absorption coefficient.

In this paper, two-phase flow and ion transportation in an alkaline water electrolysis are discussed with three-dimensional coupling numerical simulation to reveal the influence of a bubble in the alkaline water electrolysis on the cell efficiency to achieve high-efficiency energy conversion of electrical energy to hydrogen energy. Two-phase flow numerical simulation model is not a void ratio model that is mainly used in previous studies, but is a direct simulation model with Lattices Kinetic Scheme that enables microscale flow simulation. Moreover, the concentration distribution is calculated with Maxwell equation and Nernst-Planks equation, and is fully coupled to the three-dimensional two-phase flow. The numerical simulations are conducted for w/o bubble condition and w/ bubble condition with varying applied current density to evaluate the influence of a bubble at various operating conditions. The results show that the bubble in the electrolyte induces mixing flow between a bubble and an electrode, and the concentration of potassium hydroxide (KOH) around the anode is increased. This increase of concentration increases the conductivity of the electrolyte and suppresses the overpotential in the electrolyte. Moreover, the anodic activation overpotential is also suppressed by the increased concentration on the anode. These overvoltage suppressions become much more prominent at high current density operating condition of the cell. The mixing with the bubble changes the concentration around the bubble. However, concentration distant from the bubble also changes and suppresses the overpotential with the change in electrical field.

The surface velocity model is proposed for modelling the flow caused by a DBD plasma actuator. While numerical model presented up to now for the DBD plasma actuator, i.e. Suzen’s model, needs to calibrate the five parameters that must be determined by comparison with the experimental results, the surface velocity model presented here requires calibrating three parameters only. The flow by the surface velocity model is compared with the experimental results and that of Suzen’s model. When DBD plasma actuators are activated on the surface of the flat plate or on that of the circular cylinder, the induced flow appears near the electrode. And then the temporal and spatial development of the flow by the surface velocity model is consistent with the results from the experiment and the Suzen’s model. The surface velocity model is very easy to use compared with the Suzen’s model, and it can well simulate the induced flow caused by the plasma actuator.

Machining characteristics of electrochemical machining with ultrashort pulses were investigated using numerical analysis considering the inductance of a power supply circuit. In a pulse power supply circuit of ECM, stray inductance occurs in the electric feeders. Because stray inductance influences the flow of the pulse current, the formation of the electric double layer is affected by the inductance. In order to investigate the influence of the inductance on the machining characteristics, numerical analysis was conducted considering the inductance of the power supply circuit. The electric field was analyzed by numerical simulation considering the electric double layer and faradaic current, and the circuit equation of the pulse power supply was solved considering stray inductance of the pulse power supply. Analytical results show that the inductance increases the rise time of electric current flowing through the machining gap when pulse voltage is applied. Therefore, longer pulse duration of pulse power supply is necessary to form the electric double layer when the inductance is larger. The voltage continues to be applied to the working gap even after the pulse voltage becomes low, limiting the effect of ultrashort voltage pulses due to inductance.

In recent years, alkaline water electrolysis is receiving much attention on environmental issues because of hydrogen production using renewable energy. However, it is necessary to enhance the efficiency of electrolysis. One of the main causes that have effect on efficiency of alkaline water electrolysis is presence of bubbles in electrolyte. It is important to investigate the relation between bubbles behavior and efficiency of alkaline water electrolysis system. In this study, the calculation model to realize coupled simulation of ion transport, electrochemical reaction and bubbles behavior is developed and the impact of convection induced by bubbles on alkaline water electrolysis is investigated by numerical simulation. As a result, it is found that convection induced by bubbles has impact on mass transport around anode and has an effect on the efficiency of alkaline water electrolysis. Convection induced by bubbles in the vicinity of anode has an effect on ion transport to anode and anodic concentration overpotential. However, as bubbles depart from anode, this effect becomes small because convection removes ion from anode. Moreover, convection induced by bubbles shortens ion transport pass between electrodes and has an effect on ohmic loss.

A modified sintering model was presented to analyze the deformation behaviors of brazing powder compact throughout the whole sintering process, both the thermal-mechanical plastic deformation and metallic alloying were implemented as sintering driving forces in the numerical simulation by the sintering model. Ag-Cu-Sn brazing powder compacts were prepared by electromagnetic compaction technique and sintered at different temperature, the simulated deformations were in reasonable agreement with the experimental deformations. Deformation analysis with different relative density was conducted by the sintering model to reveal the volume expansion mechanism and volume shrinkage mechanism throughout the whole sintering process, it was indicated that the sintering warpage or cracks are prominently related to relative density gradients, and the higher relative density of brazing powder compacts is beneficial to sintering densification. At last, the deformation behaviors of brazing powder compacts with three typical shapes were numerically predicted to provide guidelines for tool design and sintering process optimization.

Reduction of particulate matter (PM) in exhaust gas from automobile engines is in high demand. Fuel stuck on the engine wall causes incomplete combustion, and generates a large amount of PM. To prevent this, shape of fuel injection spray must be controlled with precision. We focused on the valve offset of the injector as a factor influencing the spray shape. Computational analysis was conducted to investigate the effects of the valve offset on inner nozzle flow and spray shape (spray direction and liquid penetration). Simulated spray behavior image, footprint, and liquid penetration agreed well with experimental results. From the inner nozzle flow simulation results with the valve offset, it was found that fuel tends to flow in the direction of the valve offset near a sac in the nozzle to provide the fuel to the holes. This flow was caused by the smaller flow path fomed in the valve offset direction. From the spray simulation results, shifts in the spray direction of the plumes were caused by the flows near the sac. Some plumes were injected in the direction opposite to the valve offset. The holes with larger drill angle located in the valve offset direction, and larger valve offset caused larger changes of spray directions. Furthermore, liquid penetration was investigated. We showed that the flow separation in the holes caused by the valve offset affects the velocity distribution at the hole outlet and results in changes of the penetration length when the drill angle is small. It was found that the valve offset causes the change in the inner nozzle flow, and results in the change of the spray shape. We concluded that the correlation of nozzle geometry and valve offset is important for controlling the spray shape.

In the present study, flow in an ion-drag electrohydrodynamic (EHD) micropump was numerically simulated, and electric charge density on the emitter was modeled through the simulation. The simulation was performed for an ion-drag EHD micropump developed and experimentally tested by Kazemi et al. (Journal of Microelectromechanical Systems, Vol.18, No.3 (2009), pp.547-554.). Two models of charge density on the emitter were tested. First, one model was tested in which charge density was distributed uniformly on the emitter. The simulated discharge pressure generated in the micropump was proportional to both applied voltage and charge density. The experimental discharge pressure was reproduced by considering the change of charge density with applied voltage. Next, the other model was tested in which charge density was distributed depending on electric field on the emitter. The model was more realistic than the former because of consideration of electric field distribution on the emitter. The model also reproduced the experimental discharge pressure.

Considering that humans perform handwriting task with reduced powers by contacting elbow or wrist on a table, it is reasonable to deem that manipulators can save energy and simultaneously accomplish writing tasks precisely like humans by bracing intermediate links such as elbow or wrist. First this paper discusses equation of motion of robot under bracing constraint condition, based on the robot's dynamics with constraint condition including motor dynamics. Then a control method to utilize the constraint dynamics is proposed to control simultaneously bracing force and hand's trajectory in work space. Even though the model used for the simulation analyses is simple four-links manipulator, the simple structure can help understand even more clearly the effects got by bracing part of the manipulator. This paper demonstrates the merits of the strategy to utilize bracing by comparing the contacting motions with non-contacting motions, including ; (1) the energy consumption can be reduced; (2) the hand trajectory tracking becomes accurate; (3) there is an optimum contacting point that minimize the energy consumption on condition that trajectory-tracking task be given to the hand.

This paper numerically investigated the detail process to appear the asymmetrically spreading flames in narrow channel consisted of combustibles. We have successfully reproduced the transient process to form asymmetrically arranged spreading flame first ever in this work. 2-D, time-dependent mass and energy transport process as well as one-step chemical process in gas-phase is considered. Thick solid combustible plates (PMMA) are placed at both sides, then exactly the same ignition operation is made to initiate symmetrical processes. Pure oxygen is fed into the channel at the fixed rate to promote the spreading. Oxidizer velocity and channel height are varied as numerical parameters in this study. After the forced ignition, the combustibles are pyrolized via one-step reaction to evolve the fuel gas into the gas phase to form the opposed-mode flame spreading. Results show the distinctive three spreading modes (two-symmetric flames spreading, two-asymmetric flames spreading and one flame spreading) and transient process from one to the other mode is successfully simulated, which is hardly achieved in experiment. The asymmetric flame spreading mode appears under the limited combination of channel height and velocity. Moreover the distance between two leading edges of the flame varies depending on the imposed condition. Flow patterns are found to be sinus motion, thus the heated and accelerated oxidizer flow may enhance the reaction in the downstream. In this way, it is suggested that the flowing oxygen is effectively used to burn two fuel slabs. It is obvious that the asymmetrical configuration gives temporary stable condition. To study the details further, systematic study is demanded.

Theoretical examinations based on absorption line databases were carried out about the influence of turbulence-radiation interaction on the radiative heat transfer arriving at the wall of large-scale industrial furnaces, where the re-absorption of radiative energy by combustion gas on its path toward objects to be heated cannot be neglected. In this study, the efficient and accurate calculation method for non-gray analysis and the effective method for handling turbulent fluctuations of radiation and absorption proposed in our previous paper were coupled. Combining the above coupled method and a governing equation solver for obtaining the spatial distribution of time-averaged values of temperature, concentration, velocity and so on, the heat transfer including radiation in large-scale industrial furnaces enveloping turbulent flames was able to be evaluated with sufficient accuracy equivalent to Line-by-Line analysis and with feasible calculation load. By applying this calculation technique to large-scale furnaces, it was found that negligence of turbulent fluctuation in numerical simulation gives rise to obvious change in heat flux distribution on the side wall and in the spatial distribution of time averaged temperature. In addition, change in the total amount of radiative energy arriving at side wall caused by negligence of turbulent fluctuations is fairly small compared with change observed in the case of a typical optical path indicated in our previous report.

Soil-vehicle interaction is an important factor for predicting trafficability of off-road vehicles. Tractive forces on the wheel to drive the vehicle can be estimated by soil deformation analysis around the contact area of the wheel. Sand deformation and flow under a rolling wheel with slippage were observed from the side through a transparent acrylic wall by 2-dimensional Particle Image Velocimetry (PIV) method. The flow velocities of sand particles obtained on allocated grids revealed that periodic fluctuations of sand flow make ripple patterns on the sand surface behind the wheel. We discussed the effect of wheel slip ratios on the density of the ripples, sinkage, drawbar pull, torque and the depth of influence for the traveling wheel. The result showed that the slipping wheel forms a ripple with each scratch by the wheel rotation corresponding to the front half contact length with sand. The thickness of sand flow layer under the wheel showed thinner for large slip ratios. The finite element method was also conducted to simulate the traveling wheel experiment to discuss the possibility of the numerical simulation. The result of simulation qualitatively reproduced the experiment. However, there was a quantitative difference on the drawbar pull of the wheel, which shows that the method needs modification on the numerical model.

Vibration characteristics of a flying head slider in hard disk drives at touchdown attract strong interest because head‒disk spacing must be decreased to less than 1 nm in order to increase recording density. This study first evaluates head‒disk interfacial force based on rough surface adhesion contact models and a simple air-bearing force model. Then, microwavinessexcited vibration of single-degree-of-freedom slider model at touchdown was numerically simulated in more detail than the previous study. It was found that the slider exhibits a MW-excited vibration having low frequency components of less than 100 kHz at touchdown and shifts to severe contact state near the boundary of static instability onset. When a small static unstable region is generated by decreasing air-bearing stiffness ratio, the occurrence of the low frequency spacing variation is interrupted by temporal flying state (loss of contact). When the static unstable region further increases by decreasing air-bearing stiffness ratio, the spacing variation with low frequencies can appear only at the beginning of contact and immediately jumps to a light contact state and then shifts to a perfect flying state during a long input power range and eventually jumps to a heavy contact state. These calculated results seem to correspond to the actual slider dynamic behaviors at touchdown in the inner, outer and middle diameter regions. The possibility of surfing recording is discussed from the analytical and experimental evidences.

Blank shape minimizing earing, which is trimmed off after forming, is an important issue in sheet metal forming. In addition, blank holder force (BHF) have an influence on the product quality. Recently, variable BHF (VBHF) that the BHF varies through punch stroke is recognized as one of the advanced forming technologies. Furthermore, segmented VBHF will be valid to complex shapes for successful sheet metal forming. However, the optimal segmented VBHF trajectories and the optimal blank shape minimizing the earing are unknown in advance, and consequently the trial and error method is widely used to determine them. To resolve above issues, in this paper, a simultaneous design optimization of the blank shape and the segmented VBHF trajectories is performed. Numerical simulation in sheet metal forming is so intensive that a sequential approximate optimization using a radial basis function network is adopted to determine them. Based on the numerical result, the experiment using AC servo press is carried out. It is confirmed from the numerical and experimental result that the proposed approach is valid.

Anti-vibration effects in tennis rackets with some gum pieces are analyzed by numerical simulations using the finite difference method. The simulated results of the string vibrations show the existence of wave propagations parallel to the two-dimensional rectangle boundaries. These results are confirmed with the experimental data of the sound specter analysis in good agreements. The anti-vibration effects of dampers are measured with changing the gum piece weights using an acceleration sensor and microphones. These fitted weights are investigated for general tennis racket at 55~60 pound tensions. The string sound damping is precisely investigated using these results. The gum piece structures are discussed for searching the efficient anti-vibration effects. It is found that popular gum pieces have fairly good ability of the damping effects.

The goal of this study is elucidation of propulsion mechanism of small creatures by ciliated swimming legs. For this purpose, a ciliated pereiopod of an opossum shrimp was introduced and it was modeled with a straight cylindrical stem with 10 much narrower cylindrical poles perpendicularly projecting on the stem. Flow drag acting on the pereiopod in a steady flow, which corresponds to the thrust force by paddling of the pereiopod, was computed with a variety of clearance between each adjacent pair of cilia d and the flow velocity U. It was found that the drag increased with the increase in d to be saturated with a certain value in the range of d ≥ 0.04 mm where influence of boundary layers of adjacent cilia is negligible, and the drag agreed well with that estimated from drag of a two-dimensional cylinder. This result suggests that the opossum shrimp is propelled with the drag-based swimming and the ciliated pereiopods supply greater thrust force than tabular pereiopods with the same projection area. It was also found that the drag decreased in the range of d > 0.07 mm in which some cilia come into the boundary layer of body of the shrimp. It was optically observed that distance between adjacent cilia is around 0.07 mm on the stem and cilia near the root of the pereiopod are shorter than those near the tip. The present results suggest that the ciliated pereiopod is well designed to efficiently generate the thrust force within a limited length and mass by preventing influence of the boundary layers.

In recent years, personal mobility vehicles (PMVs) have attracted huge attentions and widely developed. Compact PMVs can move through narrow spaces and they are expected to be used in pedestrian spaces. In this study, we aim to develop a four-wheel stand-up-type personal mobility vehicle for people who cannot walk far distantly because of the pain of foot or waist although they are able to walk for a short distance. The coupled model of human and vehicle is constructed by using multibody dynamics. In the model, the vehicle is expressed by one rigid body. The wheels, body, and handle are considered as a rigid body together. A human is expressed by 8 rigid bodies (foot, lower leg, femoral, body, head, upper arm, lower arm, and hand). The vehicle of the coupled model is accelerated in the numerical simulations. The behaviors of the center of gravity of a human with and without handle constraint are analyzed. As the result of the parametric study, it is found that the center of gravity movement is smaller when the value of the maximum acceleration and the acceleration time are small. It is also found that as the angle of the upper arm becomes large, the movement of the center of gravity is decreased.

It is necessary to evaluate the geometry factor for predicting the flow accelerated corrosion (FAC) in the plant piping. Geometry factor is defined as the ratio of the wall mass transfer coefficient in the piping systems such as elbow to that in a straight pipe. In this study, the mass transfer coefficient in 90-degree elbow with curvature radius of 1.5 times the pipe diameter is computed by using large eddy simulation (LES) and is also measured with electrochemical method. Numerical simulations and experimental measurements were conducted at Reynolds number of 15000. In order to simulate the mass transfer coefficient, we adopt the analogy between mass transfer and heat transfer, and calculate the unsteady temperature field using the numerical data of LES. The experimental measurement is conducted with point electrode. However, concentration boundary layer developed over the surface of point electrode is different from that developed for whole surface of pipe wall such as FAC in the plant piping. To cope with this problem, we calculated the temperature field in the two different boundary conditions. As a typical case, whole pipe wall is heated uniformly (in this paper, referred as ‘overall heat condition’). In addition, localized area is heated to simulate working point electrode (referred as ‘point heat condition’). Geometry factor obtained from the heat transfer rate in point heat condition agrees well with that measured with point electrode, however, both of them are qualitatively different from that obtained from the heat transfer rate in overall heat condition. Analysis of heat transport revealed that heat conduction is dominant form of the wall heat transfer in point heat condition, in contrast, turbulent heat flux affects strongly the wall heat transfer in overall heat condition.

Numerical simulations of single bubble volumetric oscillations have been conducted by using Gilmore model (Gilmore, 1952), to study the influences of liquid viscosity and surface tension on the theoretical threshold value (MIt) of the mechanical index (MI) that has been successfully used for the safe application of diagnostic ultrasound. MIt is defined as the minimum value of MI at various bubble radii and ultrasound frequencies when the temperature inside a bubble reaches 5000 K. The results show that MIts for water and blood are 0.314 and 0.405, respectively. It is found that the greater the viscosity or the surface tension is, the greater MIt is. It is also found that the ultrasound center frequency that gives MIt has a negative correlation to the viscosity and surface tension.

The effects of friction on the driving mechanism using swing motion are investigated. The system comprises a body and a rod which have two and one freely rotating wheels, respectively. The rod is pinned to the body and can swing like a pendulum about the pinned joint by a servo motor. The system moves forward with or without slipping on the floor depending on the relationship of friction coefficient, swing amplitude and swing period. Effects of the parameters on the moving performance are clarified experimentally and analytically. The results demonstrate that the system is accelerated by the frictional force acting on the rod in the wheel axis direction. In addition, experimental results show that the bias angle of the rod makes turning motion of the system.

We have studied the spray atomization of a multi-swirl injector with three orifices. Hollow-cone spray interactions and the flow field inside the nozzle were investigated by experimental observations and numerical simulations. First, the effects of the spray interactions on the spray atomization were investigated by optically measuring the spray patterns and the Sauter mean diameter (SMD) using the laser diffraction. The spray patterns indicated that the sprays from each orifice interact under the orifices, and this interaction can be classified into two types: liquid-film collision and droplet collision. In the case of the liquid-film collision, the collided liquid films are supposed to merge and then break up into larger droplets. In comparison, droplet collisions have a small effect on the value of the SMD in our experiments. Second, numerical simulations were conducted to investigate the flow field inside the orifices. The simulation results showed that a liquid film was formed along the side wall of the orifice, and the liquid film of the three orifices was thinner than that of the single orifice. From the experiments conducted above, smaller SMD was measured in the case of three orifices with droplet collision. These facts imply that the droplet diameter is decreased in the case of the three orifices. Finally, we proposed a modified atomization model to calculate the mean droplet diameter of the hollow-cone spray from the film thickness and velocity at an orifice outlet. The film thickness and velocity were calculated by the internal nozzle flow simulation. Although the modified atomization model underestimates the SMD under the liquid-film collision condition, it agrees well with the measured SMD under the droplet collision condition.

Inelastic deformation of gold (Au) atomic cluster is investigated by using molecular dynamics (MD) simulations. We performed compression and unloading tests in which silicon (Si) plates approach each other and push single Au cluster of 4 nm diameter in between. Possibility of super-elastic (hyper-elastic) behavior is first discussed in the present study. The potential function of embedded atom method is adopted inside Au cluster, whereas other interactions are formulated by simplified Lennard-Jones interaction. The cluster in MD simulation shows large recovery strain which is reversible in unloading process after compression. The recovery strain is estimated on average from 5 to 10%. It is found that there are deformation mechanisms depending on temperature of the cluster. Mechanism for low temperature is based on slip motion and that for high temperature is dominated by surface reconstruction. The strength of interaction energy between Si plate and the Au cluster which may cause pulling force and produce tensile state is investigated, referring to our AFM experiment.

The growth and the deformation of the solidifying steel shell in the continuous casting process were calculated considering the taper of the mold's narrow face. The mechanism of uneven shell growth in the mold was discussed by using computational method and observations of the shell at various operating conditions such as taper and slab width. It was found that the shell at the bottom of the mold becomes uneven when the narrow face taper is insufficient. The increase of taper is effective to even shell growth， but excessive taper causes wear of mold's copper plate and breakout of the shell. To solve these problems， various kinds of mold taper design such as multiple and parabolic have been developed and adopted to molds' narrow faces. At the actual operation of continuous casting， many kinds of steel grades are cast in various casting speed and width at the same mold. So， the online change of the tilt of the narrow face is done according to the operating condition. When applying multiple taper design to this width changing type mold for slab， the problem is that the rate of upper or lower taper changes in different slab width. In this paper， the relationship between multiple taper and the uniformity of the shell growth was discussed considering slab width quantitatively by using computational model and observed shell thickness of slab. By using the developed calculation models, the multiple taper designs were optimized and applied to the actual continuous casting molds’ narrow faces.

It is necessary to evaluate the geometry factor for predicting the flow accelerated corrosion (FAC) of carbon steel piping in a complicated flow field. Geometry factor is defined as the ratio of wall mass transfer coefficient in the piping systems such as orifice to that in a straight pipe. The mass transfer coefficient behind the orifice is computed by large eddy simulation (LES) and is also measured by electrochemical method. The experimental measurement is conducted with the pipe of the test section made of Ni, in which the whole pipe surface acts as electrode (referred as ’overall electrode condition’). The obtained results are compared with the previous experiments, in order to clarify the effect of the area of the electrode, with a point electrode embedded in an insulated pipe (referred as ‘point electrode condition’). Geometry factor obtained from the overall electrode condition is larger than that of a point electrode measurement. In order to simulate the mass transfer coefficient in pipe flow, we adopt the analogy between mass transfer and heat transfer, and calculate the unsteady temperature field using the numerical data of LES. Geometry factor predicted by heat transfer coefficient agrees well with that measured in overall electrode condition. The large scale motions with vortex structure of separated flow from the orifice influence the instantaneous scalar fields. Analyses of turbulent scalar transport and space-time correlation between wall scalar transfer and flow fields reveal that the mean wall scalar transfer is affected by not only near the wall region but also the coherent scalar fields away from the wall.

Using W6Mo5Cr4V2 HSS (High-speed steel) as a sample material, effects of cryogenic treatment on residual surface stress of ground W6Mo5Cr4V2 HSS specimens were investigated. The residual stress in the ground surface and its change caused by cryogenic treatment were analyzed using both X-ray diffraction technique and finite element method. It was demonstrated that the cryogenic treatment reduced the equivalent stress Max Mises from 248.9 MPa to 114.3 MPa, and the principal stress reduced from 124.0 MPa to 91.6 MPa. The residual stress at X direction (S11) parallel to the grinding direction was tensile stress, which was reduced from the Max. 105.8 MPa to 63.48 MPa. However, the residual stress (S22) perpendicular to the grinding direction was compressive stress, which was slightly increased from 272.6 MPa to 287.8 MPa by the cryogenic treatment. The changes in both the tensile and compressive residual stress components are beneficial to material performance, e.g., wear resistance. Results from the computational and experimental analyses are consistent.

This paper reports a numerical investigation of the motion of spherical and non-spherical particles with/without gas blowing-out in a vertical uniform flow. A sphere, spheroid and pulverized coal particle are targeted in this study. The shape of coal particle is three-dimensionally modeled by scanning a coal particle using the X-ray CT method. As a first stage of the research, the Arbitrary Lagrangian-Eulerian (ALE) method is validated by comparing with the experiment. Secondly, the simulations of spherical and non-spherical particles with or without gas blowing-out in a vertical uniform flow are performed. The results show that the spheroidal particle with equivalent volume has a more similar accelerating motion to that of coal particle than spherical particle. For spheroidal particle, its distribution of PDF of CD shows a possibility to make a CD equation with Re and particle's orientation. It is also revealed that the motion of coal particle with irregular shape is significantly dependent on its shape, especially with gas blowing-out. A new model in which this complex shape effects can be considered is required to describe the irregular shape particle.

In order to efficiently develop microfluidic devices using electrohydrodynamic (EHD) phenomenon, an appropriate model for the phenomenon and a numerical simulation method for EHD flow in microfluidic devices has been required. In this study, EHD flow in micropumps was modeled and a numerical simulation code based on the model was developed. The numerical simulation code was constructed utilizing an open-source CFD software package OpenFOAM. Numerical simulations were performed using the present numerical simulation code for EHD micropumps developed and experimentally tested by Kazemi, et al. (Journal of Microelectromechanical Systems, Vol.18, No.3 (2009), pp.547-554.), and the simulations were validated by comparing with the experiments. The simulated discharge pressure generated in the micropumps was proportional to both applied voltage and charge density, and the experimental discharge pressure was well reproduced by considering the change of charge density with applied voltage. The electrophoretic mobility was assumed to be constant in the present study. This assumption was discussed based on experimental electric current, and it was shown that the assumption was valid in an applied voltage range where EHD phenomenon was dominant. With increasing applied voltage, the charge density was generated when the average electric field on the electrodes exceeded a threshold, and then the charge density was proportional to the average electric field.

When a train travels through a tunnel at high speed, large pressure variations, which act on tunnel lining, equipments inside the tunnel, and the train, are generated in the tunnel. To predict these pressure variations, numerical simulations have been developed. Usually, one-dimensional simulations are used for such purposes. Although the pressure variations caused by the pressure waves can be calculated accurately by one-dimensional simulations, they can underestimate the pressure variations in the area very close to the passing train. The resulting accuracy can be increased by using computational fluid dynamics (CFD), but CFD requires high computational costs. Therefore, this paper proposes a three-dimensional but an efficient method to calculate accurately the pressure variation in the area very close to the passing train in the tunnel. It takes into account the distribution of cross-sectional areas of the train nose and treats the flow around the train nose as three-dimensional potential flow, and the upstream and downstream boundary conditions are specified by a one-dimensional simulation in order to calculate the effect of the pressure waves. The results by this method agree well with those of model experiments by using axisymmetric train model although the discrepancy to the model experiments by using actual shape train still remains.

The existing phenomenological soot model, which unburned fuel is considered soot precursor, cannot predict the soot emission of alcohol blend fuel with high accuracy. Therefore, we proposed to introduce the coefficient Keff including the concept of Threshold Sooting Index (TSI) which quantitatively expresses the fuel sooting tendency of blend fuel. In this research, for more accurate prediction of soot emission we conducted the elementary reaction analysis of blend fuel using reduced mechanism for n-heptane, n-butanol and Polycyclic Aromatic Hydrocarbon (PAH) with 76 species and 349 reactions. Based on the clarified relationship between pyrene (A4) and TSI, we derived the equation through which Keff is calculated. By using the equation, the accuracy of the soot emission prediction was improved particularly in the low alcohol blend rate.

Walking is the human basic moving pattern and the elementary motion for human health promotion. In case of trying various measures as the moving pattern for human health promotion, the most traditional moving pattern called Nanba walking based on the biomechanics of the human body has been put into practical use. It has been thought that Nanba walking is actively focused because it is very useful for Japanese classic culture and there are many experimental discussions about Nanba walking. However, quantitative analysis of this walking pattern based on biomechanical data has not been inadequate. On the other hand, experimental study has been harder because of the difficult problem of facility. The purpose of this study are to generate Nanba walking by numerical simulation using three dimensional full human body simulation model as neuro-musculo-skeletal system including precise foot segment model developed in the past study and analyze the difference between Nanba walking and normal walking. As a result of simulation, Nanba walking was generated in order to change the feedback equation of neural oscillators. In simulation, walking characteristics such as locomotive speed and locomotive energy efficiency were optimized according to walking pattern respectively. As a conclusion of this study, it is validated as the effectiveness of Nanba walking that Nanba walking is suitable for faster locomotive speed because walking stability is also high in the single support phase by a little rotation of the upper body.

In this paper, a new vibration isolator using origami-based foldable structures is proposed and numerical simulation is performed to evaluate the performance of the isolator to prevent structural vibration. It has been known that the origami-based foldable structures using Kresling's pattern have bistability. However, that is true only if the bar elements which the structure comprises are uniformly distorted in order that the structure is symmetrically folded. To realize the bistability of the structure, we propose to apply additional linear springs to the original structure. In the first design, linear springs are applied, connecting diagonal nodes of the bar elements. In the second design, they are applied along to the axial direction of the structure. It is confirmed by numerical simulation that these designs successfully provide the bistable folding behavior and therefore, the structure with additional linear springs can work as a vibration isolator around the region that the total spring stiffness of the whole structure reaches the relative minimum value that is close to zero.