Hiroshi Tsukamoto

Kitakyushu Foundation for the Advancement of Industry, Science and Technology

Extensive experimental investigations were carried out for pressure drop and concentration profile in the flow of bi-modal slurry comprising silica sand and fly ash with mean diameter of 450 and 75 μm, respectively, at six silica sand:flyash ratios (namely, 100:0, 90:10, 80:20, 70:30, 60:40 and 0:100) in a 53 mm diameter horizontal bend. Flow veloc...

Extensive experimental investigations were carried out for pressure drop and concentration profile in the flow of bi-modal slurry comprising silica sand and fly ash with mean diameter of 450 and 75 micron, respectively, at six silica sand:flyash ratios (namely, 100:0, 90:10, 80:20, 70:30, 60:40 and 0:100) in a 53 mm diameter horizontal bend. Flow v...

To minimize the volume of argon required for on-site TIG welding of titanium plate, we investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, we designed a model of a solid rectangular shielding box consisting of 9.5 × 105 tetrahedral elements. Then, argon flow...

Pipeline slurry flow of mono-dispersed particles through horizontal bend is numerically simulated by implementing Eulerian two-phase model in FLUENT software. A hexagonal shape and Cooper type non-uniform three-dimensional grid is chosen to discretize the entire computational domain, and a control volume finite difference method is used to solve th...

We investigated heat conduction in a nano-porous silicon by molecular-dynamics simulations (MDs). We calculated the phonon dispersion curves of the nano-structured Si to understand the effects of nano-structures on phonon properties, such as phonon group velocity and phonon density of states. The dispersion curves were calculated from MD's results...

Internal flows including cavitation phenomena in a pump can be analyzed by CFD commercial codes and system performances are traditionally obtained by experimental tests. However, they cannot correctly analyze the dynamic characteristics of the system especially when the transients are very fast or the system sometimes becomes complicated according...

To minimise the volume of argon required for on-site tungsten inert gas welding of titanium plate, the authors investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, a solid rectangular shielding box consisting of 9.5 x 10(5) tetrahedral elements was modelled....

Invert traps have been successfully used to collect sediments at convenient locations within the sewer network, where large volumes of solids can be stored. In the present study, experiments have been performed in 15cm wide and 5m long channel for the measurement of retention ratios of five different invert trap configurations (namely, rectangular,...

This paper presents the result of design optimization for three-bladed pump inducer using a three-dimensional (3-D) inverse design approach, Computational Fluid Dynamics (CFD) and DoE (Design of Experiments) taking suction performance and cavitation instability into consideration. The parameters to control streamwise blade loading distribution and...

We investigate heat conduction of silicon nano-porous structures by molecular-dynamics simulations (MDs). We calculated the phonon dispersion curves of the nano-structured Si to understand the effects of nano-structures on phonon properties, such as phonon group velocity and phonon density of states. The dispersion curves were calculated from MDs r...

This paper presents the result of design optimization for three-bladed pump inducer using a three-dimensional inverse design approach, Computational Fluid Dynamics (CFD) and DoE (Design of Experiments) taking suction performance and cavitation instability into consideration. The parameters to control streamwise blade loading distribution and spanwi...

The characteristics of the blood pump for the extra-corporeal circulation is affected by the resistance of the blood circuit as well as fluctuating in biological circulation. In this study, an extra-corporeal circulation simulator has been developed. This extra-corporeal circulation system can automatically simulate the fluctuating blood pressure a...

Whirling motion of a pump impeller was calculated for the centrifugal blood pump with Conical Spiral Groove Bearings to get a criterion for the instability of impeller whirling motion. The motion of the centrifugal blood pump impeller was calculated based on a spring damping model, and unsteady flow in the pump was computed using the commercial CFD...

A valveless micropump has been developed with a diffuser/nozzle shaped channel and a variable volume actuator which produces an oscillating flow. The pressure-loss in a nozzle is lower than that in a diffuser, therefore one-way flow is considered in the nozzle direction. Frequency characteristics were determined. Simplified 1-dimentional analysis w...

The cross-plane thermal conductivity of highly oriented nanocrystalline bismuth antimony telluride thin films is investigated. The thin film was deposited by a flash evaporation method. The resulting film was oriented with the c-axis to the substrate, and was composed of fine grains with an average grain size of 150 nm. The cross-plane thermal cond...

Numerical calculation was done to estimate the flow rate in filtration of internal filtration enhanced dialyzer, in which the measurement of filtration rate is difficult. Using a finite volume method incorporated the variations in hollow fiber density with vessel taper, the effect of vessel taper was estimated. Permeability was used instead of the...

The present paper describes the mechanical losses of a swing-piston type rotary compressor, which has a groove on the outside surface of its piston and a vane engaging with the groove at the tip, compered with a rolling-piston type rotary compressor. Theoretical analysis showed an improvement in mechanical efficiency, attributable to reduction of m...

Using shadow masks prepared by standard microfabrication processes, we fabricated in-plane thermoelectric microdevices (4 mm 9 4 mm) made of bismuth telluride thin films, and evaluated their performance. We used Bi0.4Te3.0Sb1.6 as the p-type semiconductor and Bi2.0Te2.7Se0.3 as the n-type semiconductor. We deposited p- and n-type thermoelectric thi...

Numerical and experimental studies were done on unsteady flow in a pump sump to study the generation of air core vortex and submerged vortex, which cause vibration and acoustic noise. The geometry of the free surface in the test pump sump was visualized by Moire method, and velocities near pump suction were measured by PIV. Unsteady flow in the pum...

This paper presents a numerical study of unsteady flow in a target pump with an inducer, an impeller and an axial diffuser. The objective of the present study was to clarify the flow field difference between the target pump and a newly designed one at design and off-design flow conditions. The target pump showed a positive slope in its head-flow cu...

Multi Objective Genetic Algorithm (MOGA) optimization was developed for a small and high efficiency blood pump without hemolysis. The outer diameter of impeller and hydrodynamic efficiency were chosen as objective functions, and the rotational speed of impeller was chosen as a constraint condition. The measured pump performance of the GA optimized...

This paper describes the dynamic characteristics of a centrifugal blood pump with hydrodynamic levitating bearings. Flow fluctuations were realized from 0.25 to 3.0 Hz by an oscillator driver in the fluid circulatory system for the test pump with conical spiral groove bearings. The stability test was done for the whirling motion of impeller and the...

The efficiency of an artificial kidney is largely dependent on its mass-transfer between blood and dialysate. There are many factors that affect mass-transfer performance of an artificial kidney. This paper describes the effect of housing taper on dialysate flow, and an optimization of its taper length. The dialysate flow in module was calculated,...

In this paper, we describe the stability of a centrifugal blood pump with hydraulic levitating bearings in pulsatile flow, since the ventricular assist device (VAD) set downstream of heart is affected by the pulsation. The test pump was developed for VAD using conical spiral groove bearings. The flow through the pump was excited from 0.25 to 3.0 Hz...

We carried out molecular dynamics simulations (MD) of heat conduction in Si with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. The temperature is kept constant at 300K by velocity scaling. Pe...

Multi-Objective Genetic Algorithm (MOGA) optimization was developed to realize a smaller and higher efficiency blood pump without hemolysis. The hydrodynamic efficiency, impeller outer diameter, and shear velocity were chosen as GA objective functions. The measured pump performance of the GA optimized pump was acceptable as a blood pump. And unstea...

The spectral reflectance of microperiodic structures of silica microspheres was investigated. The electromagnetic dispersion relation in a close-packed structure of silica spheres is computed. The three-dimensional close-packed structures, self-assembled with silica microspheres (2 μm and 3 μm), were rapidly fabricated over a large area. Specular r...

In this paper, we fabricated a Bi2Te2 thermoelectric micro -generator, and evaluated those performances. Bi2Te2 is one of popular thermoelectric materials with the highest thermoelectric properties at room temperature. The patterned thin film of Bi2Te 3 was deposited on a free-standing Si2N4 thin film by using a flash evaporation method through sha...

An inverse transient method with genetic algorithm (GA) was applied to leak detection in pipeline. Transient flow caused by valve operation was calculated using the characteristics method. The location and discharge of leak were determined so that the difference of the calculated pressure may be minimized from the reference pressure calculated unde...

In view of developing an efficient artificial kidney module, the shape effect of hollow fibers was studied in terms of the dialysate flow. Two different fiber shapes : straight and wave-shaped ones, showed different dialysate flow distribution. We adopted a porous media model for the bundle of thousands of hollow fibers and studied axial and radial...

Pump characteristics of a Y-shaped valveless micropump were measured to investigate the effect of channel geometry for various branching angle of Y-shaped channel. The test micropumps consisted of Y-shaped channel and a variable volume chamber with a diaphragm which produced oscillating flow. Pump characteristics of four types micropumps were measu...

Multi-objective optimization was performed for centrifugal blood pumps using Genetic Algorithm(GA). In this study, a blood pump was optimized for hydraulic efficiency, outer diameter of impeller, and shear strain rate in blood pump. Performance of an optimized blood pump was measured and calculated. Performance test indicates that an optimized bloo...

Dynamic characteristics of a centrifugal blood pump with a Conical Spiral Groove Bearing (CSGB) were studied for the ventricular assist device (VAD) set downstream of the heart, the pulsation of which affects the blood pump of VAD. The radial displacement of the test pump impeller was measured, and the radial fluid force on the impeller was obtaine...

For mechanical drive steam turbines, the investigation results of corrosion fatigue phenomena in the transient zone are introduced, including basic phenomena on expansion line and actual design and damage experience. These results were analyzed from the standpoint of stress intensity during the start of cracking. In order to resolve such problems,...

Spectral directional reflectance, transmittance and emittance of close-packed structure self-assembled with silica micro-spheres are investigated. The close-packed structures of silica micro-spheres are fabricated self-assembly over a large area. Spectral directional reflectance, transmittance and emittance are measured by using an FT IR spectromet...

A valveless micropump was realized with a diffuser/nozzle shaped channel and a variable volume actuator which produces an oscillating flow. One-way flow may be realized in the nozzle direction since the pressure loss in a nozzle channel is lower than that in a diffuser channel. Pump characteristics were measured for various angles of a diffuser/noz...

We fabricated bismuth-telluride based thin films and their in-plane thermoelectric micro-generators (4mm×4mm) on a glass substrate by using the flash evaporation method through shadow masks. We prepared fine powders of Bi2.0 Te2.7 Se0.3 (n-type) and Bi0.4 Te3.0 Sb1.6 (p-type). The shadow masks are fabricated by standard micro-fabrication processes...

In this study, the thermal conductivity of a bismuth-telluride (Bi2 Te3 ) thin film is measured at room temperature by using the 3ω method [1, 2]. The 3ω method for thin films uses a single metal-line as both the heater and thermometer. An alternating-current driving current at angular frequency ω heats the surface of the sample at a frequency of 2...

We carried out molecular dynamics simulations (MD) of heat conduction in Si thin film and Si films with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. Different temperatures are applied at the...

A valve-less micro-pump was realized with just one diffuser/nozzle element. The pressure-loss in a nozzle is lower than that in a diffuser, and therefore one-way flow may be realized in the nozzle direction. The frequency characteristics and the pump characteristics are measured. Dimensionless numbers are introduced to rearrange the measured data a...

The reflection property of the close-packed structure of silica micro-spheres consists of specular and diffuse component. The characteristic of close-packed structure appears in specular component. On the other hand, the particulate systems exhibit scattering property. In this paper, the specular and diffuse reflection properties of the close-packe...

We fabricated bismuth-telluride based thin films and their in-plane thermoelectric micro-generators on a free standing silicon nitride thin film by using the flash evaporation method through shadow masks. The shadow masks are fabricated by standard micro-fabrication processes. The fabricated micro-generators are just put on a heated plate, and the...

A micro-channel with laser trapping system was fabricated to measure DNA rewinding rates of the enzyme (HsKu70). The HsKu70 with EGFP (fluolescent protein) was prepared in Ecoli., and the EGFP-HsKu70 was purified after the incubation. The fusion protein EGFP-HsKu70 is necessary for the direct visualization of the enzyme motion. A streptavidin-coate...

The effect of channel size on the characteristics of valve-less micro-pump with diffuser shaped element was investigated. The micro-pump consists of a diffuser shaped micro-channel and a chamber with a diaphragm, the vibration of which produces on oscillating flow. The pump performance of the diffuser type valve-less micro-pump with the cross secti...

A soft tube is often used for Percutaneous Cardiopulmonary Support System (PCPS). The water hammer can be occurred in the tube due to easy refraction of the tube. The water hammer can cause hemolysis and bubble generation, and therefore the effect of water hammer on blood and blood pump was studied. There were no large differences in pressure fluct...

In this study we have tested for large size models of diffuser/nozzle based valve-less micro-pump, which consisted of one diffuser/nozzle element and a variable volume chamber with a cylinder and a piston driven by a direct operated solenoid actuator. Experiment was done for the water and 7 types of the diffuser/nozzle element. As a result of the p...

The Ventricular assist device (VAD) is set downstream of the heart, the pulsation of which effects the blood pump of VAD. Therefore, the dynamic characteristics of the blood pump are important. In this study, we investigated the dynamic characteristics of a centrifugal blood pump with a Conical Spiral Groove Bearing (CSGB). The flow through the pum...

The hybrid vortex method, in which the vortex particle method was combined with the vortex sheet method, was extended to flows around a three-dimensional complex geometry boundary at high Reynolds number of O(106 ) . The computing domain was decomposed into an interior domain of vortex blobs and a thin numerical boundary layer of vortex sheets. The...

Bismuth-telluride-based alloy thin film thermoelectric generators are fabricated by a flash evaporation method. We prepare Bi0.4Te3.0Sb1.6 (p-type) and Bi2.0Te2.7Se0.3 (n-type) powders for the fabrication of the flash evaporated thin films. The overall size of the thin film thermoelectric generators, which consist of 7 pairs of legs connected by al...

In this study, we fabricated in-plane thermoelectric micro-generators (4 mm times 4 mm) based on bismuth telluride thin films by using flash evaporation method. The thermoelectric properties of as-grown thin films are lower than those of bulk materials. Therefore the as-grown thin films were annealed in hydrogen at atmospheric pressure for 1 hour i...

We fabricated micro-generator based on thermoelectric materials and measured its performance. The Bi_2Te_3- Sb_2Te_3 is used as a p-type material, and the Bi_2Te_3- Bi_2Se_3 is used as an n-type material. We fabricated shadow masks of Si with Si_3N_4 by using standard micro-fabrication processes for patterning the device. Thin films of both p-type...

The thermal conductivity of n-type nanocrystalline bismuth-telluride-based thin films (Bi2.0Te2.7Se0.3) is investigated by a differential 3 method at room temperature. The nanocrystalline thin films are grown on a glass substrate by a flash evaporation method, followed by hydrogen annealing at 250 °C. The structure of the thin films is studied by m...

In this study we have developed a valve-less micro-pump with one diffuser shaped element and a chamber with a diaphragm; the vibration of which produces an oscillating flow. The pressure-loss in a nozzle is lower than that in a diffuser, and therefore one-way flow is realized in the nozzle direction. The frequency characteristics and the pump chara...

We carried out molecular dynamics simulations (MD) of heat conduction in Si thin film and Si films with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. Different temperatures are applied at the...

In this study, we fabricated bismuth-telluride thin films and their in-plane thermoelectric micro-coolers (4mm×4mm) by using the flash evaporation method. We prepared fine powders of Bi2.0 Te2.7 Se0.3 (n-type) and Bi0.4 Te3.0 Sb1.6 (p-type). The thermoelectric properties of as-grown thin films are lower than those of bulk materials. Therefore the a...

Ventricular assist device (VAD) has been effective for cardiac patient. The VAD is set downstream of the heart, the pulsation of which effects the blood pump of the VAD. Therefore, the dynamic characteristics of the blood pump are important. In this study, we investigated the dynamic characteristics and rotor whirling motion of a centrifugal blood...

Mechanical-drive steam turbines have the heavy deposition of fouling materials on blade and nozzle path surfaces due to contamination. As a result, turbine performance tends to be deteriorated gradually. The first paper introduced this fouling phenomena and actual conventional washing procedure in order to prevent the fouling problem and its practi...

Mechanical-drive steam turbines have the heavy deposition of fouling materials on blade and nozzle path surfaces due to contaminated materials such as silica and sodium in steam. As a result, turbine performance tends to be deteriorated gradually. This first paper introduces this fouling phenomena and actual conventional washing procedure in order...

n-type bismuth-telluride thin films are fabricated by flash evaporation method. Effects of hydrogen annealing on the thin films are investigated for potential application in micro thermoelectric devices. The thin films are grown up to 1 μm on a glass substrate by flash evaporation method. The hydrogen annealing is carried out in the temperature ran...

We conducted computational fluid dynamics(CFD) analysis of centrifugal blood pumps by using commercial code CFX-5 for improvements of a thrombotic and hemolytic performance. We also investigated effects of washout holes of the impeller on thrombus formation around the shaft. Washout holes enhanced flows around the shaft behind the impeller. Numeric...

The effect of liquid viscosity on pump characteristics was tested for the diffuser-shaped valve-less micro-pump, which consisted of one diffuser/nozzle element and a variable volume chamber with diaphragm driven by a piezoelectric actuator. Experiment was done for the water and glycerin water solution (20 wt%, 40 wt%, 60 wt%). As the result of the...

DNA unwinding rates by a single Ku70 enzyme molecule are obscured in the population average of steady state, bulk phase measurements. Measurements of the exact unwinding rate in a micro-channel can be applied to new treatments for cancer, nano-machines, and so on. In this study we prepare a micro-channel, laser tweezers, DNA with micro-beads, and K...

A hydro dynamic centrifugal blood pump was developed using a Conical Spiral Groove Bearing (CSGB) is developed, whose geometry was determined based on a preliminary test. As the result of the preliminary test for the optimum groove shape, groove depth and number ware set to be 210μm, and 10, respectively. The performance test of the pump with CSGB...

We developed an Electroosmotic flow (EOF) driven liquid micro-pump. The dimension of micro-pump channels are 15, 25, 50μm height, and 500, 1000, 2000μm width. Head-volume characteristics of the present micro-pumps are measured. There are linear relationship between total head and flow rate. The maximum flow rate is 1.0μl/min at 0Pa, whereas the max...

Numerical calculations were carried out on unsteady flows in a pump sump with a cylindrical suction pipe using a commercial CFD code (CFX-10.0) in order to investigate the mechanism of the air-entraining vortex generation. The calculated results show that the dimple generated behind a suction pipe moves to the downstream with growing up, and the ai...

A hot film anemometry is developed for a flow control of a Y-shaped valveless micro-pump. The nickel thin film is deposited on a polyimide film as a heater and a temperature sensor of the anemometry. The fabricated anemometry is calibrated by using an infusion pump from 0 to 1.0ml/min flow rates. The flow rate of the valveless micro-pump is measure...

In this study, thermoelectric thin films are deposited on glass plates by using a flash evaporation method. We evaporated fine powders of 20% Bi₂Te₃-80% Sb₂Te₃ as a p-type and those of 90% Bi₂Te₃-10% Bi₂Se₃ as an n-type. We measured thermoelectric properties, su...

The phonon Boltzmann equation is solved numerically in order to study the phonon thermal conductivity of micro/nanostructured thin films with open holes in a host material. We focused on the size effect of embedded pores and film thickness on the decrease in thermal conductivity of the film. Simulations have revealed that the temperature profiles i...

We investigate the spectral reflectivity of photonic crystals assembled with silica spheres. The propagation of electromagnetic wave can be controlled by periodic structures known as photonic crystals. Therefore photonic crystals are anticipated for advanced control of thermal radiation beyond solid state properties. The close-packed photonic cryst...