In this paper, optical methods in experimental mechanics are discussed in terms of the history of academic societies, international conferences, and famous studies. Next, the author’s recent studies on the moiré and grating methods are introduced. To use these methods and techniques to provide practically useful systems for industry, it is important to develop user-friendly and reliable equipment. Some comments on this point and the future outlook for optical methods are presented according to the author’s experience establishing a venture company.

The present study investigates the vortex-induced vibrations (VIV) of a long slender cylinder under steady and pulsating flow. In this study, the VIV hydro generator, one of a small energy-harvesting device, which distributes electric power to monitoring sensors, was mentioned. The developed VIV device incorporates an elastically supported cylinder (D =25 mm) with two plate springs generating piezoelectric power, and a variable stiffness controller is installed to adjust the plate spring length according to the vortex shedding frequency. In this paper, the vibration characteristics of the elastically supported cylinder are evaluated under the laminar and the pulsating flow produced by an agricultural irrigation channel flow and a seawater exchange channel flow driven by nearshore waves. As the result, the VIV device extracts a 30-mm vibration amplitude (peak-to-peak) in steady flow (Re = 7,470–14,940), and unclear signs of a lock-in phenomenon were observed. In pulsating flow field with 0.17–0.50 Hz, the test cylinder vibrates with the lock-in frequency, as well as with the steady flow.This information is significant for setting the various parameters on VIV hydro generators.

We examine the effect of fluid acceleration on the decay characteristics of temporally and spatially decaying grid turbulence, where a spatially decaying turbulence is similar to a grid-generated turbulence. The derived forms from the governing equation of the turbulent kinetic energy show that there is a quantitative difference in the acceleration effects between the decaying turbulences. Using the observed forms, the negligible effect of the fluid acceleration in the present small wind tunnel is validated.

Recently, various studies of Micro Air Vehicle (MAV) and Unmanned Air Vehicle (UAV) have been reported from wide range points of view. The aim of this study is to research the aerodynamic improvement of flapping wing in low Reynolds number region to develop applicative these air vehicles. The six kinds of elliptical wings made of stainless steel are used in the flapping wing. The effects of flapping amplitude and wing configuration regarding the aerodynamic characteristics are investigated in detail. The fluid force measurement by six-component load cell and PIV analysis are performed as the experimental method. In the flapping wing experiment, we tried to relate the force measurement and PIV data at the same timing by means of encoder signal from the flapping motion. The relations between the aerodynamic superiority and the vortex behavior around the models are demonstrated.

The aim of the present study is to investigate the thermal fluid flow transport phenomenon of graphene oxide (GO) nanofluids in the heated horizontal stainless steel circular tube that was subjected to a uniform heat flux at its outer surface. The heat transfer and the pressure drop within flowing base fluid (pure water) were measured and compared with the corresponding data from the correlations. Consideration is given to the effects of volume fraction of the nanoparticle on the thermal conductivity, viscosity, and zeta potential. Graphene oxide (GO) nanoparticles were synthesized by the modified Hummers method. The convective heat transfer performance results show that the dispersed nanoparticles can always enhance the heat transfer coefficient of the base fluid, and the highest enhancement was obtained to be 181 % in the concentration of 0.2 vol.% of GO nanoparticles with Reynolds number 3000. The thermal conductivity enhancement depends strongly on the concentration of GO particles and increases with the increasing loading. It was also shown that the viscosity and pressure drop increase in accordance with an increase of the volume fraction.

We study a recently proposed recalibration technique for constant-temperature anemometry measurements, and address a basic issue of the scheme. First, the deviation of the output voltage from linearity was considered. A method of predicting the mean deviation was then derived and validated. The gradient of the calibration curve obtained using the recalibration method includes error at the freestream velocity, and the temporal variation of this error was approximated by a quadratic function. Finally, the predicted mean error was validated.

This paper concerned with the process of liquid atomization. The dynamic behavior of water droplet subject to surface acoustic wave was observed using a high speed video camera system. Liquid was disintegrated into fine liquid particles by the action of surface acoustic wave. The process of bursting phenomena of water droplet was revealed experimentally. Furthermore, the effect of micro solid particles in water droplet on bursting phenomena was investigated. Small spherical styrene particle was used as solid particle in the experiment. It was found that the dispersion time of water droplet was delayed by the solid particles in the water droplet. The dispersion time of droplet depended on the number of solid particles.

Chaotic mixing in four different types of curved-square channels flow has been studied experimentally and numerically. The wall of channel rotates around the center of curvature and a pressure gradient is imposed in the direction toward the exit of the channel. This flow is a kind of Taylor-Dean flow. There are two parameters dominating the flow, the Dean number De and the Taylor number Tr. Effects of four different types of moving walls, an inner wall, a top wall, inner and top walls, and inner, top, and bottom walls on chaotic mixing, are investigated experimentally and numerically. In this paper, we analyze the physical mechanism of chaotic mixing in the Taylor-Dean flow by comparing experimental results and numerical ones. We produced a micromixer model of the curved channel several centimeters long with square cross-section of a few millimeters side. The secondary flow is measured using LIF method to examine secondary flow characteristics. Also we performed three-dimensional numerical simulations with the open source CFD solver, OpenFOAM, for the same configuration as the experimental system to study the mechanism of chaotic mixing.

The aim of the study is to know characteristics of a drag force acting on a sphere in an oblique arrangement of spheres, which may be influenced by the interval and the geometrical arrangement of spheres. In the study, a passing water tank was used as an apparatus and the drag force on a sphere was measured by using a load cell in a uniform flow. The flow around the spheres was also obtained by PIV. The experiment results show the effect of the front sphere on the drag force of the rear sphere through the velocity field in an oblique arrangement. Furthermore, the drag force acting on a sphere in a triangle arrangement of three spheres was also shown.

An experimental and theoretical study was conducted to investigate the liquid metal oscillation in a U-shaped tube. Since the surface tension of liquid metal is quite large as compared with usual liquids and its tangential component is dependent on the contact angle appearing at both ends of the liquid column, the characteristics of oscillation should be strongly influenced by the static and dynamic wetting behavior of triple phase contact line. However, the past studies had considered only the inertia, viscous and gravitational force to analyze the dynamics of the oscillation. Here in this study, we proposed an equation of motion in which the hysteresis and velocity dependence of contact angles are properly taken into consideration to estimate the effect of surface tension. In the experiment, the angular frequency ω_d and damping ratio ζ of oscillation were measured for ethylene glycol-water solution and mercury in U-shaped glass tubes, as well as the dynamic contact angles dependent on the contact line velocity. The experimental results were approximated well by the theoretical model proposed here and it is inevitable to include the wetting effect to accurately estimate ω_d and ζ for mercury.

We observed two-dimensional vorticity fields on a NACA0012 airfoil in a periodic flow modeled as a gust flow with a sinusoidal velocity profile in the streamwise direction. Experiments were conducted by using particle image velocimetry in a water tunnel under conditions of Re=3.0 × 10³ and 15^∘ angle of attack. We found that phase-turbulence intensity fields illustrate the separation and reattachment points more quantitatively than do phase-averaged vorticity fields.

The performance of a hollow engine valve encapsulating sodium in the cavity was investigated experimentally and theoretically. This type of valve has been practically applied to improve heat transfer. In this study, 3D finite element heat transfer analysis and experimentation were conducted at a maximum temperature of 343 K to eliminate the effects of phase transformation; sodium is solid and does not vaporize in this temperature range. These results were then compared with previously reported results at a maximum temperature of 1073 K. The empirical temperature distribution of the sodium encapsulated valve was consistent with the calculated temperature distribution at a maximum temperature of 343 K. However, the empirical temperature distribution at 1073 K did not agree with calculated results. Instead of collecting in the bottom (head side) of the valve, apparently, sodium collects on the inner surface of the cavity at higher temperatures likely due to sodium vapor deposition.

It is well known that the lateral vibration of the trains running in tunnel becomes larger than that at open section, where we cannot find strong relevance to track irregularity in contrast to the vibration at open section. This vibration has been explained mainly by the aerodynamic flow separation and vortex shedding from the surface of trains. In this paper we focus on lateral vibration of the high-speed train (Shinkansen), and try to investigate not only flow separation but also expansion wave effect from the tail part of the trains on the vibration when they enter the tunnel. We have started to investigate with compressible and two-dimensional numerical analysis of aerodynamic flows around the trains. For the trains entering the tunnel, we performed the CFD with ghost cells and level set functions. As a result of interference of expansion waves and aerodynamic flow separation and alternating periodical expansion waves passing the train sides, large pressure difference on both sides of the trains moving forwards from the tail to the top is raised, which causes the lateral vibration.

The aim of the study is to examine the effect of the amount of the dissolved gas on the two phase flow and to examine the acceleration of bubble generation on two-phase nozzle flow by modifying the shape of orifice plate. In the experiment, the molar concentration of CO₂ gas was changed at the dissolution process. As increasing the CO₂ molar concentration, the void fraction increased and the liquid velocity decreased at the throat. On the other hand, the bubble velocity was almost constant when dissolved gas rate was changed. Therefore, the slip velocity between the bubble and the liquid increased. Moreover, the amount of bubble is different by changing the hole type of orifice plate such as different holes diameter and respective cross section area for each plate. In case of the orifice of seven holes, it cannot reach the sound speed at the throat but it is closest to the sound speed in the case of other orifices.

An experimental-numerical hybrid method is proposed for obtaining reliable and accurate strains induced by temperature change. Strains obtained from measured displacement distributions are suffered from the measurement errors. Therefore, the measured displacements are used as the input data for determining boundary condition of a finite element model. Nodal forces by the temperature change at all nodes in the finite element model are identified from the measured displacements by the proposed method. Simultaneously, the reliable displacements and the strains are obtained. Effectiveness is validated by applying the proposed method to the displacement fields in dissimilar materials under thermal load obtained by digital image correlation. Results show that the nodal forces for a local finite element model can be obtained by the proposed method and subsequent strain analysis can be performed. It is expected that the proposed method can be powerful tool for stress and strain analysis of electronic devices under thermal load.

Damping property of the damper utilizing an elastomer particle assemblage was investigated. The particle assemblage was used instead of working fluid in the damper. Basic damping property of a double-rod type damper using an elastomer particle assemblage was investigated experimentally. Forced vibration of constant frequency and constant stroke was applied to the damper. It was shown that the damping force has the hardening property of the damping force which increases with the displacement. The force depends on the stroke of vibration and the packing fraction of particles in the damper. The packing fraction of the particles increases, the force also increases.

Damping property of a damper utilizing a particle assemblage, which is the damper using a group of particles instead of oil in an oil damper, was investigated experimentally, when the particles were elastomer particles containing micrometer-size spherical particles. Silicone particles were prepared as the micrometer-size spherical particles dispersed in the elastomer particle. It was shown that the basic damping force characteristics of the damper using elastomer particles containing fine particles is basically the same as that of the damper using pure elastomer particles. The maximum damping force of the damper becomes large by dispersing micrometer-size particles in the elastomer particle. When the total volume fraction of fine particles in the elastomer particle is constant, the maximum damping force of the damper using smaller fine particles becomes stronger.

A damper using a particle assemblage is a damper using particles instead of a working oil in a standard oil damper.Two kinds of container size for double-rod type damper using a steel particle assemblage were prepared. Effects of container size of the damper, stroke and frequency of forced vibration on the damping force were investigated experimentally. The damping force of the damper depends on both the frequency of forced vibration and the length of the container of the damper, however, basic property of the damping force is almost independent of the stroke of forced vibration.

Vacuum-assisted resin transfer molding (VARTM) is commonly used to form large and complex structures from carbon-fiber-reinforced plastic (CFRP) composites. These structures are manufactured from several parts, which are joined to form the final structure. Therefore, the mechanical performance of the adhesive joints is critical. In this paper, we describe the use of a stitching technique with two different adhesive joints. The first joint is constructed with two dry carbon fiber parts, and the second from dry carbon fiber fabric and CFRP. All samples were fabricated in our laboratory using VARTM manufacturing techniques. Specimens were prepared for tensile tests to characterize the performance of the joints. The results show that the joint constructed using two dry carbon fiber parts was stronger than that using dry carbon fiber fabric and CFRP. Furthermore, the stitching technique increased the strength of the former, whereas the strength of the latter decreased when stitching was applied.

Techniques for electric current enhancement have been studied to achieve highly efficient solar cells. Localized surface plasmon resonance (LSPR) in nanostructures has promise as a potential solution in this field of technology. In particular, the deposition of nanoparticles on the surface of solar cells using sputtering has become increasingly popular due to its low cost and relatively simple methodology. However, there has so far been little consideration of the size of the deposited nanoparticles required to generate high-efficiency solar cells. In this study, Au nanoparticles were deposited on the surface of solar cells using a magnetron sputtering system. Nano-pattern characteristics (e.g., particle size, surface coverage fraction, size distribution, etc.) associated with changes in the sputtering time were evaluated. Then, the output characteristics of all the specimens were measured. A halogen lamp was employed as an optical source for the performance evaluation. The results showed that a nanoparticle size of 24 nm showed the best performance. The maximum absorption wavelength (707 nm) of the 24-nm nanoparticle was close to the maximum intensity wavelength of the optical source used (701 nm). This suggests that when developing nanoparticles, the maximum absorption wavelength of the deposited nanoparticle must be matched with the maximum intensity wavelength of sunlight to realize highly efficient solar cells.

The model electrets where only one silica agglomerate was formed by manual droplet formation (MD) were prepared using a negatively charged syringe as well as the electrets obtained by an electrostatic spraying (ES). The charge retention of the samples was measured in heating test and the dependencies of the initial surface potential and the size of silica-agglomerate on the charge retention at 250℃ (R250) were investigated. The silica-agglomerate electrets prepared by the ES method revealed that the value of R250 was influenced by the initial surface potential though the average diameter and the point density of agglomerate were almost constant. The silica-agglomerate electrets prepared by MD method demonstrated a ring-like shape though thin layer existed at the center of agglomerate. The R250 of the MD electrets was monotonically increased with the diameter of agglomerate. Furthermore, the average value of R250 of ES electrets showed good agreement with the line estimated from the relationship between R250 and the diameter of MD. Consequently, the specific surface area of silica agglomerate might be related to the dependence of R250 on the diameter although further study must be needed to clarify the mechanism of dependence of R250 on agglomerate size.

The purpose of this study is to investigate the mechanical characteristics of C/C (Carbon-Carbon) composites, where the carbon precursor contains micro-sized glass fibers. The carbon fiber bundle was dipped in the phenolic resin in which micro-sized glass fibers were dispersed uniformly and winding in order to fabricate unidirectional CFRP (CarbonFiber-Reinforced-Plastic) preform. The CFRP preform was carbonized at high temperature with inert atmosphere to fabricate the C/C composites as follows. The preform was heated up to 1273 K and then kept for 1 hr. In second phase, the preform was heated again up to 1773 K and then kept for 1 hr. The test results showed that the bending strength of C/C composites carbonized at 1273 K decreased compared with that of CFRP preform. However, the bending strength of modified C/C composites was increased when the carbonized temperature exceeded 1773 K. Unmodified C/C composites showed almost constant bending strength and modulus with respect to the carbonized temperature. These results suggested that the SiC synthesization between glass fibers and carbon matrix was effectively obtained during the carbonizing procedure.

In this study, extremely low cycle fatigue tests were performed on an aluminum alloy A6061-T6 subjected to thermal history ranging from 300℃ to 500℃, using U-notched and Hourglass cylindrical specimens respectively. The tests were undertaken under two-step strain control fatigue condition. The results are discussed in terms of effect of thermal history on the fatigue life and residual fracture ductility. The residual fracture ductility is influenced by thermal history, total strain range and cycle ratio. The fatigue life in two step fatigue is influenced by initiation of surface crack at the notch root and the thermal history.

The purpose of this study is to reveal the effect of surface nitriding on the tensile characteristics and fracture morphology of tantalum. In this study, two types of gas nitride treatment, with different surface hardness, were introduced to cold rolling tantalum. A constant tensile speed was given in the specimen until fracture. In order to investigate the nominal strain and surface strain distribution, an image measurement system was used. Hardness distribution in across the thickness of the specimen and surface morphology of fractured specimens were also evaluated. Test results showed that the fracture state of the nitride specimens could be divided into 3 stages. At the first stage, in the elastic region, due to the presence of a TaN layer, the Young’s modulus of the specimen increased as compared to that of pure tantalum. At the second stage in the strain hardening region, the tiny crack of the TaN layer was propagated due to the increase in strain. Therefore, pseudo-strain hardening would be observed because of the progressive propagation of surface cracks. At the final stage, the surface crack propagated across the width, and thus, the deformation was concentrated.

In this study, we explored the combined use of Bamboo, which has high tensile strength, and waste wood produced during Hinoki (Chamaecyparis obtusa Endl.) thinning, which has not previously been utilized effectively, in the production of high- quality plywood board. In our method, a single Bamboo plate was glued to one side of the two abutting Hinoki plates to create a single-strapped joint. The tensile strength and its dependence on the dimensions of the Bamboo plate were investigated. To identify the origin of joint separation, the adhesive layer stress distributions were calculated using the finite-element method.

This paper presents a one-dimensional wave equation that considers the circulating wave and air damping for the sound pressure distributions inside a vehicle tire. The theoretically derived sound pressure distributions inside a tire are compared with the experimental values measured by using a multi-microphone system around the cavity resonance frequency. The theoretical and experimental values show good agreement around the natural frequency of tire cavity resonance.

Ghost particles are one of the detection problems faced in tomographic digital holography using two cameras. Ghost particles are caused by reconstructed particle elongation in digital holography. In this paper, we propose a method to reduce ghost particles in tomographic digital holography by using iterative volumetric filtering. To evaluate the effect of iterative volumetric filtering, we conducted numerical simulations and calculated the signal-to-noise ratio. The results of the numerical simulation and experimental demonstration showed that this method suppresses the effect of ghost particles.

In a high-precision work, the workpiece is ground by a high-speed-spinning abrasive wheel. When the abrasive wheel is fractured due to operator error or malfunctioning, the fragments of the abrasive wheel fly apart at a high speed. Therefore, a shatterproof cover must be designed to ensure safety and prevent the collision of fragments. In this study, we investigated the collision of an abrasive projectile against a steel sheet, using a large-scale launching system. In this test, three projectiles of mass of 2.08 kg, 3.4 kg and 6.75 kg, and a SS400 steel sheet of size 750 mm × 750 mm, were used. The test results revealed three different patterns: fracture with penetration, fracture without penetration and non-fracture. From those results, we determined that the collision energy as a result of the fracture without penetration served as the boundary value, with and without penetration. In addition, assuming that the projectile and the target were a rigid body and a rigid-perfect plastic solid, the bending energy, E, was found to vary as the second power of the steel sheet thickness. Thus, it was clarified that E coincided with the predicted boundary values. This suggested that the collision phenomenon of the abrasive projectile against the steel sheet can be evaluated using the collision energy.

Infrared thermographic testing is now widely used for detecting delamination from a distance such as outer wall inspection. In this article, we would like to demonstrate infrared thermographic testing can also be used for ocean deployed buoys. First, to heat a buoy with a radiant heater effectively, spectral emissivity of the buoy paint is measured using a Fourier transform infrared spectrometer. The experimental measurement shows that the buoy paint has low emissivity in the nearinfrared region and high emissivity in the far-infrared region. Second, halogen and xenon lamp heaters are used for an effective distance heating method. The halogen lamp heater gives higher radiant energy than the xenon lamp heater because the halogen lamp heater has broader spectral energy (i.e., more energy in the far-infrared region). Infrared thermography with the halogen lamp heater can detect 5-mm diameter paint delamination at 6 m. CO₂ laser can also possibly be used to inspect delamination. However, there are several issues with this technique which should be resolved.

In order to study the optimum design for mechanical properties of balloon expandable metallic stents, comparative testing of commercially available stents was performed. The bending flexibility and the longitudinal integrity were investigated by a four-point bending test, uniaxial tensile and uniaxial compression tests, by means of developed test apparatuses and procedures. The test results revealed the practical ranges of the bending flexibility and the longitudinal integrity based on clinical experiences. The relation between the bending flexibility and the longitudinal integrity was discussed with regard to the design parameters including the number of connecters and the number of cells in longitudinal and in circumference of stents.

To develop the aerial inspection robot for infrastructures, we focused attention on EPM (Electric Permanent Magnet) as a device to stick to steel structures in past studies. Sticking ability to structures is one of the advantages of inspection robots. Although the flight experiment by a quad-rotor equipping the developed EMP unit was succeeded, the developed EPM was not able to generate enough magnetic attraction to inspect the structure. In this paper, we evaluate the effect of noise reduction in recorded images by sticking to structures and stopping rotors. The noise included in the images is evaluated based on PSNR (Peak Signal to Noise Ratio). And we develop an EPM system to stick to structures firmly, and evaluate it by measuring the magnetic attraction considering paint thickness of structures. In addition, flight experiment is carried out using the quad-rotor equipped with the EPM system to validate it.

The effects of bellows and inner pressure on the bending mechanism of a bending soft actuator, which has a rectangular cross-section divided into the upper and bottom pressure chambers in a beam structure, were investigated using a three-dimensional finite element method (3D-FEM) analysis considering large deflection. Because soft actuators are useful in fragile objects and living bodies, they have been developed and applied for many purposes. The mechanics, however, have not yet been understood because of the difficulties in predicting the 3D deformation that alters the rigidity of the actuator. In the present study, the deflection and generated force were calculated, and then the result was compared with empirical data. Consequently, the following results have been obtained: (1) the bellows structure shows a greater deflection angle than the straight structure probably because of the enhancement in the rigidity and (2) the analyzed deflection angles were consistent with the experimental result; however, the forces in the analysis did not agree well with those obtained in the experimental result. It has been suggested that the difference is caused by the Mullins effect showing hysteresis in the stress-strain curve of rubber materials, since the deflection angles were measured after the experimental data of generated force were obtained.

In previous studies, the experimental results for the transformation plasticity coefficient in terms of three-point bending system and tensile-torsional-compressive system were different with the same heat treating case for the same tested material. Therefore, in this study, bending-tensile loading system have been proposed to analyze the transformation plasticity behavior and determine the transformation plasticity coefficient. The specimens of S45C steel were heated to austenitization temperature and kept at this temperature for several minutes, then naturally cooled to room temperature. During cooling process before transformation start, bending and tensile stresses have been applied on specimen and have continued to the end of experiment. The maximum bending deflections due to austenite-pearlite transformation have been examined with different loading conditions and then transformation plasticity coefficients were determined. The obtained transformation plasticity coefficient of pearlitic transformation were compared with the results of other test methods such as three-point bending system and tensile-torsional-compressive system.

On March 11, 2011, a very big earthquake occurred in the Tohoku district in Japan. Huge tsunami was generated by this earthquake and the coastal area of the Tohoku district had catastrophic damage. A large amount of tsunami sludge deposited on the bottom of many rivers. As a result, many rivers do not satisfy the planned flow cross sectional area. Furthermore, many banks had a serious damage by this earthquake and tsunami. Therefore it is urgently necessary to reinforce the bank, but it needs a large amount of soils. If the high quality banking materials can be produced from the tsunami sludge, the effective construction will be possible. However, the tsunami sludge do not have enough function as banking materials because the durability is extremely small. In this study, we focused on the application of the fiber-cementstabilized soil method to banking materials. The characteristics of Fiber-cement-stabilized soil made of tsunami sludge deposited in the river as banking materials were experimentally investigated.

In recent years, an “On-site Visualization” method has been proposed to measure the deformation of structure, and to visualize the measured results by different colors of light in real-time for personnel conducting field measurement. Based on this concept, a mechanical method is introduced in this paper to monitor small deformations in tunnel structures such as the cracks of concrete lining. It consists of a rotational structure, which is used to transform the linear relative displacement into the movement of rotation. The other component is a small rectangular mirror which is mobilized to rotate by the rotational structure. An observer can see the reflected image of the colored mark by means of the mirror from a certain distance. If the mirror rotates as the displacement increases, the reflected image of the mark would move at the same time and eventually disappear from the mirror. As a result, the displacement can be identified visually by the changing reflected image of the colored mark and its value can be read directly from the width of the shifted mark. The mirror size and the distance between the observer and the mirror determine the accuracy of the method for measurement. In this paper, the fundamental experiments were carried out to verify the feasibility and effectiveness of the method. The authors believe that this mechanical method could improve the safety management of tunneling, mining and rock slope engineering.

This study investigated the mechanical properties of polymeric fiber ropes for harvesting wind energy using an airborne wind rotor at high altitudes. The tensile fracture load and rigidity of the ropes are very important for the safety issue and the efficiencies of the power transfer from the wind rotor to the ground. Our results indicated that the tensile fracture load of the ropes decrease as the number of torsion increases, and that there are no significant differences in the power transfer efficiencies of three rope samples used in this experiment, i.e., cotton, cremona, and nylon rope samples. Thus, our finding suggested that nylon can be the most proper material among the three rope samples from the safety improvement for harvesting wind energy using an airborne wind rotor.

Cavitation (expansion of air bubbles) often occurs in xylem elements and blocks water transportation. Such a cavitation can be detected by an AE sensor attached to a stem because it generates acoustic emissions. Reducing the cost of the sensor, however, is a significant problem for the practical use of AE techniques in agriculture. In this study, we tried to detect AE owing to cavitation in the stems of plants using a low-cost acceleration sensor (ACC sensor) instead of a conventional AE sensor. Artificial AEs traveling a bar of balsa wood were measured using a conventional AE sensor and a wideband ACC sensor to compare the sensitivity. Then, the AE measurement of a miniature tomato was conducted using both sensors. The peak frequency of the signals detected by the ACC sensor while measuring an artificial AE was much lower than that of the AE sensor, although the signals detected by the AE sensor were reflected by the vibration of the actuator. The AE waveforms detected by the ACC sensor were also deeply related to the resonance frequency of the sensor. The AE occurrence rate of the ACC sensor, however, was similar to that of the AE sensor when the ACC sensor was attached to the stem of the plant by a hose clamp.

There are two types of desulphurization processes in the steelmaking industry: the KR process and injection process. In the former process refining agents such as CaO particles are initially placed on the bath surface and then dispersed in the bath using an impeller. Meanwhile, the refining agents in the latter process are introduced into the bath with a carrier gas such as Ar and N₂. The efficiency of the two processes depends strongly on the dispersion pattern of the agents in the bath. The agents are usually poorly wetted by molten metal. The main objective of this water model study is to make clear the wettability effect of the agents on their dispersion pattern in the bath. As a first step, many poorly-wetted spheres were simultaneously introduced into a water bath. The dispersion patterns of the spheres were observed with a high-speed camera.

As a fundamental study of enhancing the efficiency of the current desulphurization process, water model experiments were carried out to understand the behavior of refining agents entering a molten iron bath. The agents such as CaO particles are usually poorly wetted by molten iron and carried into the bath together with a carrier gas. The penetration depth and residence time of the agents in the bath is strongly responsible for the efficiency. The main objective of this water model study is to make clear the wettability effect of the agents on their entry in the bath. A pair of spheres of different wettability and different diameters was simultaneously introduced into a water bath. An air cavity was formed under every experimental condition. Its scale was mainly dependent on the larger sphere. The penetration depth of larger sphere was favorably compared with an analytical solution for a single sphere penetrating into a water bath.

We propose a method of observing the generation of cathode spots at arbitrary times during AC tungsten inert gas (TIG) welding. The observation system includes a high-speed video camera and multi-data acquisition system. First, to accurately observe cathode spots generated during AC TIG welding, we synchronized the data logger and high-speed video camera. Next, in setting the start time for photography by the high-speed video camera, a time delay was set. The observation of cathode spots in the AC TIG welding of pure aluminum confirmed that we could accurately observe the cathode spots generated only during the tungsten electrode-positive polarity. In addition, we attached a timer immediately before the data logger in the system, and set a specific delay time because the system only allowed us to observe cathode spots during the early stage of the AC TIG welding process. The improved system allowed us to observe the generation status of cathode spots at any time during the welding process. The usefulness of the proposed cathode spots observation system was thus verified.

The influence of plasma discharging conditions on the formation and growth of nano-wires formed on tool steel substrates (JIS: SKH51) was studied. Various sample settings and plasma discharging conditions were employed and the specimen surface was observed by scanning electron microscopy. The plasma discharging involved two steps: predischarging (introduction of Ar) and discharging (introduction of Ar and H₂). Nano-wires were formed on the substrate when the sample setting, pre-discharging, and discharging conditions were appropriate. The growth behavior was influenced by the H₂ flow rates used during discharging and by the pre-discharging and discharging time. The measured top surface substrate temperature during plasma discharging exceeded 700 K when the radio frequency power was 500 W. The top surface substrate temperature was an important factor influencing nano-wire growth. The length and diameter of the nano-wires increased with increase in log(discharging time). We presume that the growth was controlled by diffusion due to the increase in temperature.

The transport phenomena of copper through successive phases of molten iron, silver and sodium sulfide has been investigated at 1473 K in order to investigate the possibility of copper removal in iron. The dependence of the distribution ratio of copper between sodium sulfide and iron, L_Cu (=(mass%Cu)_{in Na2S}/[mass%Cu]_{in Fe}) on the sulfur content of iron is investigated at 1473K. Silver can keep iron from being sulfurized, which enables to maintain the high copper capacity of sodium sulfide. For this reason, the L_Cu value increases with an increase of sulfur potential. The copper transfer proceeds at lower 0.1 mass%Cu in iron, and the copper content of iron decreases to 0.068 mass%. The silver also prevents sulfur from being transferred into the iron, and the sulfur content of iron can be kept lower.

Hollow particles are gas-filled spherical particles with single or multiple voids; they have advantageous properties such as low effective concentration and high specific surface area. In this study, we developed a simple method for fabricating hollow particles made of widely used chloroprene rubber. Hollow particles with voids less than 10μm in particle size were obtained by stably maintaining microbubbles or aqueous microdroplets inside a solvent droplet with dissolved chloroprene rubber.

In order to utilize lower quality of iron ores with high Al₂O₃ contents, it is important to understand the influence of Al₂O₃ contents on reducibility of iron ore agglomerates. Reduction behavior of iron ore agglomerates of FeO-CaO-SiO₂- Al₂O₃ were investigated under 30vol%CO-70vol%N₂ gas mixture at temperatures from 1000 to 1200°C at 5°C/min. The samples contained Al₂O₃ contents of 0, 2, 4 mass%. The reducibility of iron ore agglomerate decreased by Al₂O₃ contents of 2, 4 mass% over 1100°C. This result was caused by lowering the reducing gas diffusion rate into an unreacted region of agglomerate. Considering this, it was suggested that initial melt formation started and some pores of agglomerate was blocked by the initial melt over 1100°C. In-situ observation of initial melt formation behavior in an iron ore agglomerate was performed from 1000°C to 1310°C at 5°C/min by using a scanning laser microscope. The initial melt formation shifted to lower temperatures with increasing Al₂O₃ contents, and the amount of melt also increased.

People sit on chairs for long periods of time each day and hence it would be convenient for them if they could exercise while sitting. This paper proposes a chair with a forward-declined seat and a footrest for allowing the user to exercise while sitting. When sitting on the chair, the user has to apply forces through his/her legs and feet to prevent slipping down from the seat. In the experiment, first, the required moment on each body joint was calculated using a digital mannequin positioned on a 3D-model of the proposed chair, and the active muscles were identified. Next, electromyography (EMG) of the identified muscles was performed in sitting on the proposed chair and other types of chairs. After the EMG measurements, the subjects provided their subjective impressions on topics such as the ease of sitting on the chair for a long time. Finally, after comparing the results from the EMG and subjective impressions, it was confirmed that a user of the proposed chair was able to exercise while sitting on it.

Currently, it is desired to incorporate force feedback into medical robots. In this study, a three-axis load measurement sensor mounted on the tip of forceps was developed. The newly developed sensor electrodes are threedimensionally arranged. From the simulation, the effect of the taper angle on the load measurement was revealed. A taper angle θ =π/4 rad is the most suitable angle for the measurement of the normal and shear loads. As a result, by measuring the normal load applied to each zone, this sensor can calculate the normal load and shear load.

The purpose of this study was to quantitatively analyze the stress and deformation that occur in plastic ankle-foot orthoses (PAFOs) during walking after it is trimmed. First, PAFOs with incorporated sensors were individually prepared for 2 patients with hemiplegia. Mechanical data were then obtained while individuals wore the PAFOs during walking. Here we report the results of mechanical data and finite element analysis of trimmed plastic ankle-foot orthoses worn by two patients with left-hemiplegia. The results could provide prosthetists with some suggestions for forming orthoses.

Biomass is a composition of various types of waste materials that can be utilized as useful form of energy. However this new kind of energy hasn’t met its full potential in production of energy especially electricity generation due to its lower performance in terms of thermal efficiency. In this decade, within the raising from biomass energy, the cocombustion and carbon emission reducing are the trend for the energy industry. For this study, we used vege-oil as the main material and under emulsion with water and surfactants to simulate using aquatic biomass material for next stage application. Samples are evaluated by visual effects, and selected threes types of surfactant for heat value testing. The emulsion samples are able to tested and the heat values are close to simulated results. This method is able to apply in the aquatic biomass materials, such as algae.