This study discusses controls of flapping flights of butterflies. Free-flying motions of butterflies are measured in a low-speed wind tunnel of an experimental system. A numerical model realizes a free flight by repeating a joint motion, whereas the flapping flight is unstable. A feedback control is designed and it successfully stabilizes the free-flight motion of the butterfly model. The control of a living butterfly is analyzed by comparison between an experimental observation and a numerical simulation. Maneuver is realized by constructing a servo controller. The transient response of control variables of the artificial control are similar to that of the living butterfly.

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In order to understand butterfly's flapping flight, necessary is an accurate numerical model, which requires small computational costs. This study makes a numerical model where the butterfly body is modeled by rigid bodies, and the fluid dynamics are calculated by panel method, which is a kind of vortex method based on the potential flow theory. In terms of fluid dynamics, forces applied to wings and the flow field are important. Therefore, results obtained by numerical simulation should agree with experiments. With respect to flow field, visualization of velocity vector field and isosurface of Q-criterion are used as the way to compare between experiments and simulations. In experiments, the motion of a butterfly, flow field, and fluid forces are obtained. The numerical results of the spatial pattern of induced flow and the vortex structures are in good agreement with experiments. In addition, the experiment, a model using viscous fluid and the panel method generate similar results in fluid forces. Hence the model in this study is appropriate for the purpose.

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This paper is concerned with the biomechanics of insect flight. The experimental study on the free flight of a butterfly, Colias erate, was conducted with the high speed video camera. The take-off flight of the butterfly in the laboratory was observed, and the posture of butterfly body in the rising flight was analyzed using personal computer. It was found that the butterfly generates a rising force even in the upstroke of wing flapping. The flexibility of butterfly wings during insect flapping was revealed. The mechanism of butterfly flight in take-off and rising movements was discussed.

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The insect obtains driving force and lift force by flapping. The dragonfly changes its flapping state of four pieces of wings according to flight conditions. The wing performance of the robot dragonfly which was able to fly was measured in order to grasp its flight states in a wind tunnel. The followings were obtained by this study: Unsteady lift forces by flapping wings were confirmed to be about three times larger than those of fixed wings. The aerodynamic performance was varied by the phase difference of fore and hind wings. Lift force exceeding the body weight was obtained in flapping phase angles of the hind wing advancing for the forewing at the time of -90° and 0°. Chronological aerodynamic performance in flight conditions were obtained to analyze the phase difference of fore and hind wings.

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In this study, the effect of wing flexibility for flight stability of a hovering hawkmoth is investigated numerically. To reproduce the wing deformation, an in-house computational fluid dynamics solver was coupled with computational structural dynamics solver. Using this integrated model, we achieved analyzing of a hawkmoth's flexible wing. Additionally, to investigate the difference of stability and maneuverability between the rigid and flexible wing, the wing kinematics was altered to three cases. The wing beat cycle-averaged aerodynamic torque of pitching increased in the altered wing kinematics model and the difference of cycle-averaged aerodynamic torque of pitching between rigid and flexible wing models, was more increased in the flexible wing model. These results may help knowing how to control the artificial flyers which have flexible wings in a hovering and forward flight and other maneuverability.

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Hummingbirds are the only species in birds capable of performing continuous hovering flight. However, the precise aerodynamic force generating mechanisms, which should be associated with the dynamic wing-morphing, still remains unclear. In this study, targeting at hummingbird Amazilia amazilia, we aim at conducting a systematic analysis of flapping-wing kinematics and dynamic configuration of the wings during hovering flight. With use of a filming system consisting of four synchronized digital high-speed video cameras operating at 2000 frames per second, we recorded a sequence of hovering with sufficiently high resolution. With the video images, characteristic points on the right wing of the hummingbird were tracked. Additionally, we conducted the flapping experiment to evaluate the effect of the wing-morphing on lift generation. Two time-variant wing deformation parameters were obtained: wing surface area and spanwise twist. We found that the wing area shows a variation up to 20% within a wingbeat cycle. Our results indicate that the time variation of the angles between adjacent primary feather shafts is the main cause of the variation of the wing area. The wing twist shows asymmetric variation during upstroke and downstroke, and this asymmetry is prominent for the inboard part of the wing. The hummingbird-inspired flapper experiment shows it is generating sufficient aerodynamic force to support the original hummingbirds weight based on which it is modeled.

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In this study, a fluid added mass effect on an insect flapping flight was evaluated numerically. The flapping flight of the model wing dynamically similar to that of Diptera was developed using our fluid-structure interaction (FSI) model proposed previously. Our computational FSI analysis validated here was applied to the model flight with three different wing masses, one of which gives the inertial effect dynamically similar to that of the dipteran insect, while the others of which give the ignorable inertial effect. It follows from the present results that the dipteran passive pitching motion and the lift force generation would be enhanced by the inertial force due to the wing mass.

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Motion of an object falling in the air is determined by an interaction between the object and the airflow, which greatly depends on the detailed shape of the object. Torahiko Terada studied the overturning of the cone, and determined the relationship between the initial height and probability of the overturning experimentally. Analysis of such falling motion is not easy because the object-air interaction is determined by a dynamic flow structure produced by the motion, which depends on not only the position and velocity of the object but also the history up to the time considered. In this study, we focus on the overturning dynamics of the cone, and performed experiments to obtain the time-series data. Using the experimental data, we propose a mathematical model. We found that the function proposed in Terada's mathematical model does not match the experimental data. Using the experimentally based function, we succeeded in reproducing the experimental results, of the probability of the overturning behavior by introducing stochastic fluctuation to the initial angle.

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The bird varies the way of walking by physical size. A relatively big bird does bipedalism by right and left legs alternation. There are no big birds by hopping with two pairs of legs together like a sparrow. Generally, the movement of the creature is optimized by the living form, and the physical form changes, too. And the optimal motion is classified with emergency motion and normal motion. The walking gait is the least cost of energy consumtption. From the viewpoint of energy cost, both of the walking of a big bird and the hopping of a small bird should be a movement of the least cost of energy consumption related to their physical structure.

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Lumbar interbody spacers used in posterior interbody fusion are made of titanium alloy which has a much higher elastic modulus than bone. Therefore, the induction of stress shielding may become a problem. In an effort to increase mechanical stimulus to the lumbar spine we propose changing the material of the spinal interbody fusion implant from a titanium alloy to plastic (PEEK - polyetheretherketone). We proposed using a spacer and casing rod made of PEEK and we conducted the following experiments to determine on effective design of spacer and casing rod. CAD data of the lumber spine (L4, L5) consisting of cortical bone and spongy bone, and the lumbar implant were created. FEM analyses were performed by varying the thickness of the spacer and the inner diameter of the casing rod with a load of 700N to simulate a standing position. We found a large amount of strain is applied to the interbody with the casing rod of 4mm inner diameter. Also excessive stress is observed in the spacer that has 2mm thickness. Therefore, a 2.5mm or 3mm spacer is advised. A future study will analyze flexed spinal positions.

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The newly developed side-faced-type multi-fingered haptic interface, consisting of a five-fingered haptic hand and an arm, can presents three directional forces at a user's five fingertips. By locating the interface on the side of the user's body, the interface allows the user to grasp and manipulate a small virtual object by his/her multiple fingers. However, there is the risk that the user's hand and the haptic hand will collide while the user is manipulating the interface. In this paper, we develop the control system to realize the interference avoidance between the user's hand and the haptic hand, and we presents the experimental results of the control system, which show the validity and the great potential of the side-faced-type multi-fingered haptic interface. Further, we also present the discussion about the applicability of the side-faced-type multi-fingered haptic interface.

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For the purpose of promoting the use of the woody biomass as fuel for the greenhouse heating, it is necessary to know how to keep the thermal environment in the house at better conditions. In the case of hot-water heating, the temperature distribution in the greenhouse becomes uniform by increasing the heat transfer area of the hot-water supplying line. On the other hand, warm air heating has a possibility to give a stress to a plant locally. We consider that the hot-water heating is the easy heating method for a better thermal condition to the plant.

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The purpose of this study is to study the application to healthcare with carbon dioxide micro-bubbles from a micro-bubble generator patented by Sadatomi and Kawahara. Carbonate spring is known to be effective to improve bloodstream in human body medically and warm the body. In this study, a hand and foot were immersed in carbonate hot water which was produced by using the present generator. Every five minutes, the surface temperatures of the hand and the foot were measured. The effects of carbon dioxide flow rate and carbon dioxide concentration on the surface temperature were examined. As the results, the produced carbonate spring was found to be effective to increase the temperature.

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This paper discusses risky slips which cause falls through the loss of upright balance due to sudden movement of the feet at certain accelerations. The validities of various methods to measure frictional properties were examined, so as to evaluate fall-risks while stepping barefoot on slippery floors covered with soapsuds. 70 subjects aged 65 and over participated by stepping barefoot on seven different flooring surfaces covered with soapsuds by various walking patterns. The percentages of most risky slips, which cause falls through the loss of upright balance, were calculated for each flooring surface. In the ramp test, another 60 elderly subjects participated by descending a slope on each slippery flooring surface. The validities of five different types of testing methods including the ramp test were examined. Overall results show that the most reliable testing method as an index of fall risks on the slippery floors was the ramp test method..

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A razor is a cutlery which closely touches the skin in daily life. And the razor cutting performance arises from the shape of blade edge, the surface coating, and the design connection between blades and plastic parts. In general, the cutting performance can be evaluated by measuring the cutting load. But it is not clarified how the causes for razor cutting performance stimulate the human sense. In this study, the relation among the razor components, the cutting performance and the skin condition after shaving was experimentally investigated. As the result of investigation, we found the differences in shaving insufficiency, cross-section surface of beard and cutting load when comparing the razor samples with PTFE and the ones without it. One of the pain causes in shaving is that the beard was pulled, and the loads were different for feeling the pain depending on a part of the face. With the test result of cutting performance, it is found that more painless shaving can be achieved by using the PTFE blades.

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Tribological phenomena are not only revealed in non-biological materials, but also those can be seen in biological phenomena. In this presentation, I would like to introduce with my findings how a dynamics in a motor protein system can be understood and how the findings are utilized and developed in the recent works by other researchers. Until now, I studied in a field of muscle contraction and other motor proteins. On the other hand, I recently have worked in another field of aging and lifespan. Thus I will additionally discuss one possibility that aging and lifespan can be considered as a tribological problem.

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Utilization of renewable energy was attracted attention in recent years. Among them, water power generation lends itself to Japan which possesses many aquatic resources, however, a large-scale infrastructure is required to do this. We propose a new power generation method using a number of very small and light units that are biomimeticly sealed. The units, called"Bio-Star", use a polyethylene glycol (PEG) solution and Polyvinyl formal (PVF) within the shaft seals, which reproduce the elastohydrodynamic lubrication and weeping lubrication that are observed within joint cartilage. In this report, We discuss the frictional characteristics of these biomimetic seals. To measure the frictional characteristics of the PVF seal, a motor turns the sealed shaft at 20 rpm while a 100N load is applied perpendicular to the seal housing. A torque meter then measures the shaft's resistance to rotation. Moreover, PEG solutions of molecular weight 2 million and a PEG mixture of 0.5 and 0.02 million are employed for lubricating liquid. As a result, PVF seal materials with cavity diameters below 700μm showed high coefficients of friction and the PEG solution of molecular weight 2 million showed a much lower coefficient of friction compaired to the mixed solution.

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Renewable energy research has been promoted to slow down climate change and maintain economic growth. Streamflow is valued as a source of energy, and environmentally friendly and low-friction sealing system that employs biomimetic technologies is proposed for its utilization. A dynamo-electric generator and ancillary systems with waterproof construction are installed under water. Lip seals with a rotating shaft function to prevent the ingress of water from the outside and excellent frictional properties with various rotation speeds are required to improve the power generation efficiency with constantly changing water flow. The sealing system was successfully developed using a hydrated material (polyvinyl formal; PVF) that mimics articular cartilage in a natural synovial joint. Polyethylene glycol (PEG) dissolved in distilled water, which is a non-Newtonian fluid, was used as a lubricant. These materials have low toxicity and low environmental impact. The biomimetic sealing system exhibits excellent frictional properties with extremely low ingress of water.

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For the new energy saving on fossil fuel combustion, we have developed the successful technique to improve the temperature exchange efficiency at the heat exchange region by absorbing thermal radiation energy emitting from CO_2 in the combustion exhaust gas through the electro-magnetic radiant materials, which are applied at the inner surface of combustion chamber. This is named as "CO_2 Spectrum Heat Absorption Technique".From several kinds of verification tests such as diffusion flame as fundamental research and fire tube and flue boiler as the practical boiler, we may predict that CO_2 spectrum heat absorption technique is very useful and effective to achieve the high energy saving through the improvement of thermal efficiency on fossil fuel combustion.

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A non-imagining solar concentrator, which is composed by involute reflectors, compound parabolic reflectors and tubular absorber, was designed and the concentrator was covered by evacuated glass tube to eliminate conductive and convective heat losses. In order to decrease the material cost and to increase ray acceptance, truncation effect was evaluated. Optimum truncation level was decided by some different ways. The ray tracing model was used to evaluate optical and thermal performance. The efficiency was compared to full size of the proposed solar concentrator.

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The objective of this study is to investigate heat transfer and fluid flow characteristics of spandrel panel. Spandrel panel has been using as a house wall which is a collector of solar thermal energy. The spandrel panel is a construction steel board having cyclic grooved pattern. In order to improve performance of the spandrel panel as a heat collector, it is necessary to improve an efficiency of heat transfer from the spandrel wall to the air in the panel. Therefore, the method for enhancing heat transfer such as inserting the porous material into flow channel of the spandrel panel is expected an effect of expansion of area which generates heat transfer and thermal radiation. We have carried out a numerical analysis of natural convection in spandrel panel using the commercial CFD code. This paper describes the heat transfer and fluid flow characteristics of inside channel having grooved pattern when inserting the porous material into flow channel. From the results, it was found that the gas temperature was increased by inserting the porous material but the amount of heat removed was decreased by inserting the porous material.

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In the contact type temperature measurement as a thermo couple and so on., there is a problem that it has a heat loss to a sensor. Objective of this study is to build a catoptric type infrared thermometry system which enabled microscopic and high-speed temperature measurement. The catoptric type infrared thermometry system used in this research had spatial resolution which could recognize a detailed structure near an infrared wavelength. And we tried measurement of the evaporation process of the water from the micro porous medium.

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The exact power managements for a shaft of a vessel are needed for energy-saving operation of the vessel from cost reduction and global environment problems, and energy-saving regulation in international marine transportation. It is necessary to measure strain which occurs in a revolving shaft in order to control exact power and to transmit multipoint measurement data out of a system from the revolving shaft. But, it is not easy to measure power of the revolving shaft. The optical fiber sensing systems are used for structural health monitoring. The optical fiber can have functions both as a sensor, which can measure strain and temperature at different locations, and a transmission path. Therefore, strain distribution can be measured with higher accuracy. Here, the monitoring system for the revolving shaft which measures the multipoint data from the optical fiber attached to the revolving shaft is proposed. We confirm the performance of the shaft power measurement system using the optical fiber.

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Mass transfer characteristics in gas diffusion layer (GDL) are closely related to performance of polymer electrolyte fuel cell (PEFC). Thus, it is necessary to clarify the characteristics of liquid water distribution, microscopic conformation and oxygen diffusivity in the GDL. In this study, a hybrid type GDL was examined to control the liquid water movement in the GDL and achieve both oxygen diffusion and moisture retention. In particular, the oxygen diffusivity and visualization of liquid water in the GDL were simultaneously measured using a galvanic cell oxygen absorber and X-ray radiography using beam line at SPring-8. As the result, the formation of oxygen diffusion paths was visualized; the pores in the hybrid GDL were formed from hydrophobic region, and the pores spread to the untreated region after the formation of the pores in the hydrophobic region. Thus, the formation of oxygen diffusion paths in the hydrophobic region enhanced the oxygen diffusion characteristics.

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Mechanical reliabilities of membrane electrode assemblies (MEA) in polymer electrolyte fuel cells (PEFCs) are a major concern to fuel cell application. Hygro-thermal cyclic conditions induce the mechanical stress in MEA and cracks are formed under operating conditions. The purpose of this paper is to understand the fatigue properties of MEA under several mechanical and environmental conditions for the critical design of durable PEFCs. We carried out fatigue tests for MEA both in room condition and in a test chamber in which temperature and humidity were controlled. The surface crack formation of MEA was observed by a video micro scope during the fatigue tests and the number of cycles to crack formation was measured. The results revealed that the fatigue strength of MEA was shorter under higher temperature and higher humidity condition. Moreover, ionic conductivity of MEA was affected by mechanical fatigue damage and it may result in the power loss of fuel cells. Therefore, the design of crack prevention in MEA is important.

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The mechanical properties of a recycled carbon-fiber-reinforced plastic (rCFRP) were investigated. The rCFRP samples consisted of epoxy resin with 60% carbon fiber (CFRP) and acrylonitrile butadiene styrene resin. Five different weight fractions of CFRP were selected from 0 to 70% of the total. The ultimate tensile strength (UTS) increased gradually with increasing CFRP content, but the UTS dropped considerably for the CFRP70% sample. Similar to the tensile strength, the fatigue strength increased with increasing CFRP content. However, despite one of the samples having low tensile strength (CFRP70%), relatively good fatigue properties were obtained. This was influenced by the low crack driving force stemming from severe crack closure. The crack growth behaviors were analyzed using a crack closure model.

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Strength was examined by internal pressure fracture tests for press-formed hemispheres from woven continuous Carbon Fiber/PPS (Poly Phenylene Sulfide) composite sheet under various forming conditions, in order to study how forming process affects the strength of press formed parts. Miss-orientation of fibers to loading direction due to variation in fiber shear angle caused during the stamp forming to semi-spherical shape is supposed to affect most significantly on strength. Concerning press forming conditions, it was clarified that the fracture pressure varied with blank hold force in spite that formed shape and resulting fiber shear angle was the same, and on the other hand it was not affected by die temperature.

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In this study, degree of carbonization and tensile properties of green composite using carbonized jute fiber (CJGC) were investigated. Before fabrication of CJGC, carbonization was conducted to the jute fibers in atmosphere.Carbonization temperatures were 300℃ and 400℃. Heating rates were 2℃/min and 60℃/min. Holding times were Ohr, 3hrs and 6hrs. CJGC was fabricated by using carbonized plain woven jute fiber and polylactic acid (PLA). The static tensile test was conducted. Crosshead speed was l.0mm/min. As a result, the young's modulus of CJGC(2℃/min) was improved in comparison with that of CJGC(60℃/min).The tensile strength of CJGC(400℃) was improved in comparison with that of CJGC(300℃). The young's modulus of CJGC(Ohr) was improved in comparison with that of CJGC(3hrs,6hrs). These results implied that carbonization temperature, heating rate and holding time affected the tensile properties of CJGC.

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This paper investigates analytically and experimentally the cyclic fatigue behavior in piezoelectric ceramics with a crack normal to the poling under alternating current (AC) electric fields. Fatigue tests were performed in three-point bending with the single-edge precracked-beam (SEPB) specimens, and numbers of cycles to failure under sinusoidal mechanical loads and AC electric fields were obtained. Finite element analysis was also conducted using a phenomenological model of domain wall motion, and the energy release rate was calculated. The effect of AC electric fields on the maximum energy release rate versus number of cycles to failure curve was then discussed. The important conclusions are that when the AC electric fields with the same phase of the sinusoidal mechanical loads are applied to the cracked piezoelectric ceramics, the number of cycles to failure becomes smaller and the slope of the maximum energy release rate versus number of cycles to failure becomes steeper.

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Bimorph piezoelectric actuators were subjected to cyclic electric loading with bias DC voltage V_b=0, 50, 100V. When specified number of cycles was preceded, electric loading was interrupted and resonance and anti-resonance frequencies were measured by an impedance analyzer. In addition, displacement of the actuator due to DC voltage was measured by a laser displacement meter. Electromechanical coupling coefficient k_<3l> and piezoelectric constant d_<31> were calculated from resonance and anti-resonance frequencies and the relationship between DC voltage and displacement of actuator. Degradation of bimorph piezoelectric actuators due to cyclic electric loading with positive bias voltage was indicated. Moreover, variation in material properties of piezoelectric ceramics used in actuators under cyclic electric loading was indicated, too. When the positive bias voltage was superposed on AC electric loading, piezoelectric ceramics below the center electrode was depoled, and it was found that the degradation of actuators was caused by the variation in piezoelectric material properties due to the domain switching.

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In this paper, a one-dimensional elastodynamic problem in a functionally graded piezoelectric infinite thin film is considered. It is assumed that the film is initially in the stress-free state, one surface is subjected to an impact pressure, and the other surface is fixed to a flat rigid body. The nonhomogeneous material properties are assumed to be expressed as exponential functions of the space-variable. Applying the techniques of the space-variable transformation and Laplace transform, an exact analytical solution for the displacement, stress, and electric potential which satisfy the initial and boundary conditions is obtained for two cases of variation in material properties. The functions of the displacement, stress, and electric potential derived for one case are different from those derived for the other case. It is seen from numerical results that the time history of one stress is monotonic and periodic and the waveform of the stress oscillation remains unchanged, whereas that of the other stress is quasi-periodic and the waveform changes as time advances.

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To prevent the global warming, it is desired to develop eco-friendly electricity generation technology. For this sake, various types of generation technology utilizing renewable energy, such as wind power and solar power, have been already developed and are in operation. But the amounts of electric power generated by these technologies are smaller than those by thermal power or nuclear power plants. Thus it is important to increase the diversity of the electricity generating methods. In this study, fluid-elastic vibration of tubes subjected to cross flow will be utilized. This vibration sometimes causes the failure of tubes in the heat exchangers such as a boiler and a steam generator, and conventional researches focus on the methods to suppress this vibration. But if we focus on this vibration from the other aspect, this vibration has very large energy, because tubes take in fluid energy very efficiently. Therefore, we propose a new method to generate electricity from fluid-elastic vibration of tubes. Here, we fabricate a fundamental flow-induced vibration model of tubes and investigate the possibility to harvest energy and to generate electricity from fluid-elastic vibration. We employ electromagnetic induction as electric power generating.

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Thermal fatigue crack may initiate at a mixing tee where high and low temperature fluids flow in and mix. In order to prevent piping failure caused by thermal fatigue, an evaluation procedure of fluid temperature fluctuation at mixing tee using numerical simulation has been developed in the Japan Ageing Management Program for System Safety (JAMPSS) supported by the Nuclear Regulation Agency in Japan. The developing process and the current research issues are discussed in this paper regarding to the estimation method of temperature fluctuation in pipe wall using numerical simulations. This paper also describes the effect of grid fineness and inlet conditions on the simulated temperature fluctuation downstream from a T-junction.

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CFD simulations based on LES was applied for the thermal striping phenomenon in a T junction pipe. The CFD models of several mesh size were used to evaluate grid convergences for temperature fluctuations. Fluid temperature fluctuations show some grid dependencies, but metal temperature fluctuations show good grid convergences and its order is same as experiments. These results means that high frequency temperature fluctuations induced by local flows like a karman vortex can be represented. Another important issue is to find some signs of low frequency temperature fluctuations by the branch stream swaying. Low temperature frequency fluctuations has possibilities to cause serious thermal fatigue damages in piping. A hypothesis of the mechanism of branch stream swaying was presented.

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In piping system of a nuclear power plant, high-cycle thermal fatigue may occur due to stress amplitude in piping material of branch pipes induced by fluctuation of interface between hot water and cold water, which is called "thermal stratification layer". This study focuses on a position of the thermal stratification layer in a vertical branch pipe. Numerical simulation using transient Reynolds-averaged Navier-Stokes approach was carried out to clarify the relationship between main passage velocity and the thermal stratification layer position with varying the main passage velocity from 4 to 10 m/s. The simulation results showed that the thermal stratification layer positions corresponding each velocities were over predicted in the comparison with the experimental results of the past study. The discrepancies were between from 115 mm to 298 mm in the branch pipe with 43 mm diameter.

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Temperature fluctuations generated by the mixing of hot and cold fluids at T-junction, which is widely used in nuclear power and process plants, can cause thermal fatigue failure. The existent evaluation method of thermal fatigue provides insufficient accuracy for the evaluation result, because it was developed based on the limited experimental data and the simplified one-dimensional FEA. CFD/FEA coupling analysis is expected as a useful tool for the more accurate evaluation of thermal fatigue. The present paper aims to verify the accuracy of numerical methods of simulating fluid and structure temperature fluctuations at T-junction for thermal fatigue evaluation. The dynamic Smagorinsky model (DSM) is used for LES sub-grid scale (SGS) turbulence model, and a hybrid scheme (HS) is adopted for the calculation of convective terms in the governing equations. Also, heat transfer between fluid and structure is calculated directly based on thermal conduction by allocating grid points within the thermal boundary sub-layer. The simulation results show that the distribution of fluid temperature fluctuation intensity and the range of solid temperature fluctuation are close to the experimental results. Moreover, the peak frequencies of PSD of both fluid and solid temperature fluctuations also agree with the experimental results well. As a result, it has been proven that the numerical methods used in the present paper are of high accuracy.

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Thermal fatigue failure of pipes induced by fluid temperature change is one of interdisciplinary issues for long term structural reliability. In this work a special focus was put on the effect of thermal and loading histories on high cycle fatigue crack growth behavior. In order to get basic understanding on this article the fatigue crack propagation tests were carried out in a low alloy steel which experienced several kind of loading and/or thermal histories. Both the effects of stress ratio, test temperature on the fatigue crack threshold, and the change in the threshold depending on the thermo-mechanical loading histories, were experimentally investigated. It was shown that the thermo-mechanical loading history left its effect along the prior fatigue crack wake resulting in the change of fatigue crack threshold. Some discussions are made on how this type of loading history effect should be treated from engineering point of view.

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In order to assess the thermal fatigue caused by the local temperature fluctuation, it is important to evaluate the stress gradient in the thickness direction in addition to the stress on the surface. In this study, the stress distribution in the depth direction was investigated for various constraint conditions in order to predict the crack initiation and growth behaviors. Not only a sinusoidal but also a trapezoidal fluid temperature fluctuation was analyzed. It was shown that the stress range on the surface caused by the trapezoidal fluid temperature fluctuation could be more than aEΔT/(1-v) for low frequency condition without the membrane constraint, and it could be 2 aEΔT/(1-v) at the maximum. The SIF was derived by the weight function method using the evaluated stress distribution. It was shown that, even under the thermal stress fluctuation, the crack can penetrates the wall thickness without the threshold SIF ΔK_<th> for crack arrest. If the ΔK_<th> was considered, the crack may stop growing under a sinusoidal fluid temperature fluctuation without the membrane constraint. The reason for the arrest of crack growth at the mixing tee and the crack penetration at the branched elbow was reasonably explained from the analyzed results.

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A testing method (membranous pressure method) for investigating fatigue strength under equi-biaxial stress/strain condition has been developed. In this method, the failure of the specimen was defined as the number of cycles when a crack penetrated a specimen. The strain range was largest at the center of the specimen and decreased with the distance from the center and crack grew to the edge of the specimen even if it was initiated at the center of the specimen. It might affect the number of cycles to failure because the strain range measured at the center of the specimen was used for evaluation. In this study, the influence of theses characteristics of the membranous pressure method was evaluated by investigating the crack initiation and growth behavior during the fatigue test. Periodic penetrate inspections were made by interrupting the test and the change in a crack size was identified. It was shown that, although the crack length at the failure was about 3 mm, it has little influence on the number of cycles to failure. It was concluded that the number of cycles to failure obtained by the membranous pressure method can be compared with those obtained by a general uni-axial fatigue test without correction.

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A model of combustion simulation is studied in a waste furnace using the DEM (Discrete Element Method), to estimate the ash particle of burned waste convecting in the exhausted gas. The predicted result, such as the particle size distribution of fly ash and its flow behavior, can be seemed to show the few observations and the few measurement results in the tested furnace of JAEA.

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It is very important to grasp failure probability and a failure mode appropriately to carry out risk reduction measures of the nuclear power plants. To clarify the important factors for the failure probability and failure mode of the pipe subjected to the temperature change, failure probability analyses changing the values of a stress range, stress ratio, stress components, a threshold stress intensity factor range were performed. The important factors for the failure probability are temperature fluctuation range, stress ratio (mean stress condition) and effective threshold stress intensity factor range. The important factor for the failure mode is temperature fluctuation circumferential angle. When a large temperature fluctuation acts on fully circumferential surface of the pipe, the probability of pipe break increases, and measures to prevent such a failure and to reduce a plant risk are demanded. When the circumferential angle subjected to a temperature change is small, the failure mode is the leak and the corrective maintenance might be applicable at the point of view of the plant risk.

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This paper deals with the high cycle thermal fatigue phenomenon at a T-junction. The case of the phenomenon is a turbulent mixing at a T-junction, where hot and cold temperature fluids are mixed, in a plant piping system. The current guideline for high cycle thermal fatigue at pipes published by the Japan Society of Mechanical Engineers does not provide any procedure to measure actual safety margins, although both design and maintenance of nuclear plants need quantification of safety margins. Therefore, this paper proposes a new reliability assessment method for thermal fatigue in piping which considers loading and strength uncertainties to quantify safety margin. Since the procedure of the method should be concise for practical use, the proposed method uses the new concept "equivalent stress amplitude" which makes the complicated loading easy to deal with. Due to its conciseness and low calculation cost, the proposed method can contribute to introducing reliability assessment to the guideline for thermal fatigue evaluation.

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The temperature oscillation produced by thermal stratification phenomenon induces thermal fatigue damages on structures of nuclear components, which should be prevented. To evaluate thermal fatigue, the frequency response function was developed. However, this theoretical method does not take particular effects of thermal stratification oscillation into account. To clarify these effects, finite element simulations were conducted with two fluid temperature models. Based on mechanisms of the effects, the frequency response function was improved. Agreement with the results of the finite element simulations confirmed the proposed function.

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Two ultrasound based methods for simultaneous characterizations of instantaneous velocity profiles of two-phase (liquid and gas) flow have been explored. Measurements of velocity profiles of both liquid phase and gas phase have been carried out for bubbly counter-current flow in a vertical pipe of 5cm pipe diameter (liquid flowing downwards and gas upwards). Two ultrasonic basic frequencies, 2MHz and 8MHz, are used independently and simultaneously along the sound path for measurement of bubble and liquid velocities respectively. The measurement methods are therefore referred to as the ultrasonic multiwave method. For signal processing, one method uses the ultrasonic Doppler method (UDM) and the other uses the ultrasonic time domain cross-correlation (UTDC) one. Based on the measured results, assessment of each method, when they are applied to this particular case of two-phase flow, is clarified.

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Nondestructive inspection of a high temperature structure is required to guarantee the safety of it. However, there are not any useful sensors for high-temperature structure. Some of them can't work at high temperature over 50℃. Another one is too expensive to use it. Therefore, the sensing system which can transmit and receives an ultrasonic wave which travel long distance by using a long waveguide has been studied. It means that an ultrasonic sensor could be drive at atmospheric temperature. We could confirm that a guided ultrasonic wave generated by a trial electromagnetic acoustic transducer (EMATs) can travel more than 10m for using a thin bar with a 2mm - diameter as a wave guide. However, we had a difficulty to receive a reflected ultrasonic wave from the bottom surface of a test specimen. We tried to improve the trial inspection system by using an ultrasonic horn. Finally an experiment that the temperature of a test block was heated up to about 300℃ has been done and reflected ultrasonic wave from the bottom surface of it has been detected successfully by using the long waveguide and the wave horn.

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The measurement of transmitting and receiving ultrasonic vibration was performed for the purpose of non-destructive evaluation of water potential. The AE sensor and laminated piezoelectric actuator were installed on the stem of mini tomato's true leaf and the propagation characteristics of the ultrasonic vibration were measured. The water potential, furthermore, was measured by the pressure chamber method. Then, the correlation between ultrasonic characteristics and water potential was investigated. The center frequency of the FFT spectrum of the detected waveforms, fw was decreased with the decrease of water potential. Such a degradation of fw might be caused by the increase of the attenuation of the ultrasonic vibration in the range of high frequency when the stem was wilted due to falling water potential.

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Giant Magnetostrictive Materials (GMMs) that can generate magnetostriction, which is about 50 times greater than the magnetostriction of ferrite magnetostriction materials, have recently developed. It may be possible to use the GMM as an ultrasonic transducer which can achieve a remote drive. Furthermore, the GMM's Curie point is about 380℃. This means that this type of ultrasonic transducer can operate at a high temperature. In this study, an inductionbased method was used. An induced electromagnetic wave activates the GMM and generates the giant magnetostriction. The magnetostriction generates an ultrasonic wave and the reflected ultrasonic waves from the bottom surface of the steel sample also induce an electric current which activates the coil. In this study, the dependence of the received ultrasonic wave signal on the drive condition of the coil was studied. The experimental results indicated that the GMM may be used as a remote sensing sensor.

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In this study, we applied non-contacting NRUS (nonlinear resonant ultrasound spectroscopy), and nonlinear three-wave mixing method to evaluation for fatigue damage in aluminum alloy plates subjected to zero-to-tension cyclic loading, These methods were resonance-based techniques exploiting the significant nonlinear behavior of damaged materials. In NRUS, the resonant frequency of an object was studied as a function of the excitation level. As the excitation level increases, the elastic nonlinearity was manifest by a shift in the resonance frequency. In nonlinear three-wave mixing method, two intersecting ultrasonic waves produced a scattered wave when the resonance condition was satisfied. The wave amplitude was measured. NRUS and nonlinear three-wave interaction method exhibits high sensitivity to micro-structural change of the damaged material. It rapidly increases from 60 % of fatigue life to the fracture The sensitivity in three-wave interaction methods was higher than that in NRUS. These noncontact resonance-EMAT measurement can monitor the evolution of nonlinear acoustic characterizations throughout the fatigue life and has a potential to assess the damage advance and predict the fatigue life of metals.

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The guided wave is a kind of an ultrasonic wave and is used for the non-destructive test of huge structures, such as a pipeline. When defects exist in the structure, such as a slit and thinning, the propagation behavior of the guided wave is very complicated. Therefore, development of the interpretation of the measured guided wave is necessary in the on-site inspection. The authors have studied the guided wave measurement using PVDF. Then, the combination of the magnetostrictive transducer and the PVDF sensor will be applicable for sophisticated interpretation of the guided wave inspection. In this paper, the guided wave of a test specimen with a defect is measured using the combination, and the results are discussed.

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In this study, we monitored the change of acoustic nonlinearity with electromagnetic acoustic resonance (EMAR) during creep damage in 9Cr steel welded joint, under lOOMPa, 923K. Resonant frequency shift by nonlinear ultrasound spectroscopy (NRUS) and second and third harmonics were measured as the nonlinear acoustic parameters. These were resonance-base techniques exploiting the significant nonlinear behavior of damaged materials. EMAR was combination to electromagnetic acoustic transducer (EMAT) with resonant acoustic technique. We used axial shear wave EMAT to monitor NRUS and harmonic amplitude of SH wave propagating in the circumferential direction of sample surface. Axial shear wave EMAT was operated with the magnetic strain effect. Furthermore, use of EMAT makes non-contact transduction possibility. NRUS detected damage by using resonant frequency shift. In measurement of resonant frequency shift, as the excitation level increase, resonant frequency was shifted and manifested the elastic nonlinearity. Measurement of harmonics with EMAR, drive of EMAT at half or one third the resonance frequency, the standing wave generate the second or third-harmonics by nonlinear effect. In addition, ultrasonic attenuation measured simultaneously. Measured nonlinear acoustic parameter showed the peak at 25% of creep life. We assumed that these trends were resulted from the increase of void density and the change of dislocation structure.

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