The ultimate goal of the shape optimization is that standard deviation of the stress distribution becomes zero (each members in a structure has the stress of the same level). And shape optimization software is developed towards this goal and popularized steadily, but its output shape is drastically different from conventionally designed shape. In this context, the example that the sympathy of the expert design engineer is obtained through the comparison with the analysis solution, visualization by 3D-Printer.

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This work proposes a homogenization method for micropolar elastic bodies aiming at their multiscale optimization. Micropolar continuum theory is a generalized continuum theory and enables us to accurately analyze certain materials that have singular properties due to their microstructures. The main difference between micropolar continuum theory and classical continuum theory is that in the former, each material point has independent rotational degrees of freedom in addition to usual translational degrees of freedom. In order to generate materials with new or improved properties not found among existing materials based on multiscale optimization for micropolar elastic bodies, we need to formulate a homogenization method in which heterogeneous materials can be replaced with mathematically equivalent homogeneous materials. In this work, the governing equations for both the microscale and macroscale are developed through an asymptotic expansion. Numerical examples are shown to confirm the validity of the proposed homogenization method and the potential for multiscale optimization.

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This paper presents a numerical solution to shape identification problem of steady-state viscous flow fields. In this study, a shape identification problem is formulated for flow velocity distribution prescribed problem, while the total dissipated energy is constrained to less than a desired value, in the viscous flow field. The square error integral between the actual flow velocity distributions and the prescribed flow velocity distributions in the prescribed sub-domains is used as the objective functional. Shape gradient of the shape identification problem is derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. The validity of proposed method is confirmed by results of 2D numerical analysis.

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Objective functions are often conflicting in real-world engineering design problems. When such conflicts exist in a multiobjective optimization problem, non-dominated solutions called a Pareto optimal solution set can be obtained. Obtaining a broadly distributed Pareto optimal solution set can be highly beneficial because this enables trade-off analysis among conflicting relationships and increases flexibility when making engineering design decisions. Therefore, this paper proposes an aggregative gradient-based multiobjective optimization method that ensures the diversity of solutions. The proposed method utilizes an aggregative search strategy in which multiple points are concurrently updated during the optimization process and a multiobjective optimization problem is converted to single objective problem using a weighting method. The design variables at all points are updated based on a local optimization. During the updating process, the proposed method introduces distance constraints among all points to maintain the diversity of non-dominated solutions. A numerical example is provided to confirm the effectiveness of the proposed method.

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Solar panels are installed on fixed-tilt racks because of easy construction at various capability of installation locations. They are installed at roof, wall, ground surface, slope and so on. The amount of light received at fixed panels is affected by shade, seasonal variation of solar orbit, the latitude and the clear sky rate of the installation location and the area. In this study to increase the amount of light received at fixed solar panels, optimization method is applied to determine the optimization parameters relating the installation configuration and the inclined angle of panels. Several optimization examples to demonstrate the effectiveness of the optimum design of the solar panel configuration are shown in this paper.

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DAKOTA (Design Analysis Kit for Optimization and Terascale Applications) toolkit is developed by Sandia National Laboratories, and available under a GNU Lesser General Public License (LGPL). DAKOTA provides the following 4 capabilities; (1) optimization with gradient and nongradient-based methods, (2) uncertainty quantification with sampling, reliability, stochastic expansion and epistemic methods, (3) parameter estimation with nonlinear least squares methods, and (4) sensitivity/variance analysis with design of experiments and parameter study methods. JAGUAR (JAva GUi for Applied Research) is a Java software tool providing an advanced text editor and graphical user interface to manipulate DAKOTA input specifications. In this paper, we report the results of the capabilities of DAKOTA, especially optimization. DAKOTA is applied to some famous optimization examples and is verified that outputs are correct. DAKOTA is applied to the gradient-based local methods with constraints, the derivative-free global method, and multi-objective problem, to confirmative its optimal capabilities. Additionally, DAKOTA is compared with other optimal system.

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It is difficult to make the quantitative assessment of accident reduction effect of driving safety support systems in a real world. Therefore we try to predict the traffic accident reduction effect by simulation as the pre-stage or the alternative of the test in the real world. First for this purpose, we need to reproduce traffic accidents in the traffic simulator on the same mechanism as the real world. In this paper we describe the approach to reproduce the traffic accident and how to take advantage of the traffic accident simulation. Through a number of sensitivity analyses, we can analyze the generating mechanism or the condition set of a very rare traffic accident, and evaluate how intelligent-transportation-system (ITS) technology would work in the situation that causes traffic accidents.

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We can reproduce traffic accidents on a traffic simulator by implementing drivers' error in a driving phase such as recognition, determination and operation. Since traffic accidents are the phenomena that cause serious damage but have quite low probability, it is difficult to obtain statistical prediction. Therefore, the approaches to identify the types and regions of the parameters contributing significantly to the occurrence of traffic accidents from a vast parameter space may become more effective. It is important to execute simulations efficiently and to manage the simulation results for the sensitivity analyses. In this paper we describe a framework that has been developed to execute and manage a huge number of parametric studies.

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Dynamic behavior of a seatbelt is estimated by the numerical simulation method based on the drop weight test result of the seat belt under the pre-tension force. Material property of the seat belt to simulate dynamic behavior is identified through iterative simulations changing its Young's modulus value. The effect of mesh size of the simulation model on the simulation results is also considered. As results of this study, a modelling method including material property and mesh size are presented.

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When two vehicles meet at the intersection, the vehicle on the non-priority road has to slow down to avoid the vehicle crash. This paper describes the velocity control model of the vehicles on the non-priority road. The models are the multi-leader models based on the Helly and optimal velocity models. The validity of the models is discussed in the numerical simulation.

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Vehicle Platoon is very effective for increasing the traffic capacity and enhancing the traffic safety. This paper describes the vehicle velocity control model of the four-vehicles platoon. The vehicle platoon simulation of four LEGO Mindstorms is performed. The experimental result is compared with the simulation result in order to confirm the validity of the model.

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Traffic accidents are major concern even though technologies such as ITS are being develop. It is important to predict where and how traffic accidents might occur, and to know how to prevent traffic accidents. Traffic simulators that have the function of simulating traffic accidents can help users to predict them. Our goal is to make a traffic simulator which can reproduce traffic accident and can be used for simulating real city. In this paper, we develop new traffic accident models and implement them to an existing traffic simulator. We considered drivers' errors and classified them into four patterns for modeling traffic accidents. We reproduce traffic accidents in a realistic situation by modeling traffic accidents depending on the environment surrounding the driver.

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The purpose of this study is to clarify the mechanism about behavior of artery by experimental approach. As the first step, two evaluation methods of the arterial deformation characteristics are introduced to analyze the mechanism. One of them is to identify the viscoelasticity from blood pressure and pulsatile deformation of tube. The other one is to evaluate the deformation characteristics from pressure and reaction force by pinching of the vessels. These methods are validated in artificial device which imitate the circulatory organ of human. As the result of the validation, the viscoelastic method can evaluate separately the elasticity and the viscosity of the tube at the same time. Further, it is suggested that the possibility which the pinching method can identify the elasticity of the tube effectively.

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In this paper, the validation method on the mechanical behavior is presented for the evaluation of diagnosis technique of aneurysm. In the aneurysm diagnosis, one of surgical problems is to judge the rupture risk of it in human body. Then the mechanical approach of its analysis is tried to be realized for the establishment of low-invasive diagnosis. Here, the status of aneurysm is evaluated by the mechanical behaviors of pressure, deformation and reaction force. In order to validate the evaluation methods, artificial circulatory system is used with some fundamental measurement devices. Then evaluated results are applied to simulate the behavior of aneurysm by using commercial analysis software, and the availability of the validation method presented here is discussed for future development.

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Rheological behavior of interstitial fluid in epidermal tissue, including blood micro-circulation, can vary skin mechanics in micro scale, i.e. visco-elasticity. Therefore, an in vivo quantitative measurement of fluid velocity is necessary to clarify their properties. In this paper, we propose OCDV (Optical Coherence Doppler Velocigraphy), which is a method of tomographic micro-visualizing interstitial fluid velocity using a high frequency modulated low coherence interferometer. The tomographic detection of modulated Doppler frequency can determine fluid velocity profile within tissue. OCDV system was constructed on the signal processing of Hilbert transform, and validated by measuring the fluid velocity of Intralipid solution (2%) in micro channel. Consequently, Hilbert transform has further advantages in the accuracy even with a rapid scanning system than short time FFT. OCDV was suggested to be effective to diagnose flow velocity profiles in tissue.

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In our previous research, a new subcutaneously implanted bone conduction hearing aid has been proposed. The hearing aid is composed of an external unit and an internal unit. The external unit consists of a microphone, a sound processor and a transmitting coil. The internal unit consists of a receiving coil and a vibrator. The vibrator is made of giant magnetostrictive material (GMM) which deforms its length in response to change of surrounding magnetic field. The internal unit is embedded under the skin and vibrates the temporal bone when the magnetic flux is supplied by the external unit. Prototype vibrators have been developed, but excitation force of the prototypes was inadequate especially in low frequency range. In this study, the shape of the vibrator case was improved to enhance the excitation force. The new-type vibrator has a high output at all frequencies compared with the conventional prototype. To consider the shape of slit which has the quality to last long and high output is an issue in the future.

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Authors have developed Dynamic OCSA, which provide tomographic distribution of deformation velocity dynamically based on cross-correlation technique using OCT images. In this study, the present method was in vivo applied to forearm skin tissue to evaluate viscoelastic behavior related with complicated micro-biomechanics of superficial skin structures as tomographic distribution of creep recovery time. As a result, creep recovery time around capillary vessels was observed to be larger, where there is fine and soft collagen and viscous effect of microcirculation. Consequently, it was confirmed that Dynamic OCSA can non-invasively visualize space-dependent and time-dependent biomechanical properties as creep recovery time.

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Many of the elderly are predisposed to develop osteoarthritis (OA), although it is quite difficult to diagnose the early-grade OA even by latest imaging modalities. In this study, we have proposed Dynamic OCSA (Optical Coherence Straingraphy), which is a tomographically micro-visualizing method of visco-elastic properties estimated from continuous OCT images. This is based on the speckle tracking algorithm, which is composed mainly of the recursive cross-correlation and the sub-pixel analysis, e.g. upwind gradient method and image deformation method. These are applied continuously to the synthetic OCT images, then can provide temporal and spatial distribution of not only deformation velocity but also strain rate. This was experimentally applied to comparatively both normal cartilages and cartilages degenerated by the collagenase enzyme treatment. Consequently, the strain rate was observed to be spatially localized within the superficial tangential zone. Additionally, the attenuation of time-varying strain rate was visualized to be lager in the superficial zone than that in the middle zone. There appeared to be the significant increase in attenuation with increasing the treatment time. It is, therefore, possible to diagnose the degeneration of the early-grade OA, taking the attenuation of relaxation modulus into consideration.

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Pronation-supination movement of the forearm is very important to ensure smoothed motion during daily and sports activities. Since abnormal motions in the radioulnar joint during pronation-supination may cause distal radioulnar joint diseases, evaluation of the three-dimensional (3D) position of the radioulnar joint is necessary in order to elucidate the development and progression of the distal radioulnar joint diseases. The purpose of this study is to present an in-vivo method for analyzing 3D forearm motion with low radiation exposure and high accuracy. This method combines calibrated bi-plane X-ray imaging (frontal and lateral views) and CT scan of forearm to create 3D radius and ulna models. The 3D positions of the radius and ulna were recovered by matching the projected outline of the 3D bone model with the calibrated bi-plane x-ray image of the corresponding bone. Bi-plane X-ray images of forearms of 5 normal subjects were taken at the 90° of pronation, 45° of pronation, neutral position, 45° of supination, and 90° of supination. The relative position of the radius with respect to the ulna was evaluated during pronation-supination. Dorsal-palmar and radius-ulnar translations of radius were larger than proximal-distal translation. Maximum translation, 21.2 ± 3.8 mm, was found in dorsal-palmar direction at 90° of supination. Rotation about proximal-distal axis of radius was much larger than those about dorsal-palmar and radius-ulnar axes. Rotation angle reached its maximum value, 64.0 ± 11.1°, at 90° of supination.

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The tooth axis is an important as a morphological reference axis; however general definition of the tooth axis has not been established. This study presented a novel method of automatically calculating three-dimensional teeth axes in micro-CT images. In this study, 20 teeth specimens were obtained from five incisors, canines, premolars and molars, respectively. X-ray images were obtained using a micro-CT scanner at a spatial resolution of 33×33×33μm^3. The tooth axis was calculated using a principal component (PC) analysis on the segmented soft pulp and dentin. The teeth axes of PC-A_+ and PC-A__ were defined as the including of the pulp and not, respectively. No significant differences were noted in the experimental results between PC-A_+ and PC-A__. In experimental results using 20 teeth, the average relative angular errors between the teeth axes T-A manually specified by five dentists and automatically calculated PC-A_+ by the proposed method were 1.14±0.11 deg for incisor, 1.74±0.74 deg for canine, 3.51±0.43 deg for premolar and 2.90±0.57 deg for molar, respectively.

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The metacarpophalangeal joint (MCP joint) is a diarthrodial joint that permits flexion and extension, abduction and adduction, and rotation (pronation and supination) of the proximal phalangeal base (PPB) on the metacarpal head (MCH). Determination of the distribution and magnitude of joint contact area is necessary to understanding the effects of loading on articular cartilage. For example, accurate assessment of MCP joint contact area is needed for various methods used to quantify joint stress such as mathematical modeling and finite element analysis. Traditionally, such data have been obtained from cadaver specimens. Recently, Magnetic Resonance Imaging (MRI) was shown to be a valid method of quantifying the joint contact area indicating the potential for in vivo assessment. In this study, MRI was used to quantify in vivo MCP joint contact area, contact distribution and joint motion. Eight males participated in this study. Cartilage-enhanced MR images were obtained at -30, 0, 45, 60 degrees finger flexion. This study highlights the differences in MCP joint contact area and joint motion between different finger flexion postures and geometries of joint surfaces.

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The knee ligaments are giving stability to the knee joints. Main function of the posterior cruciate ligament (PCL) is to prevent the posterior dislocation of the tibia with respect to the femur. The PCL reconstruction surgery is performed in case of the functional impairment by ligament damage. However, a clear footprint of the PCL is not determined. Therefore, the operative procedures and the bone tunnel positions in PCL reconstruction are entrusted to the discretion of the operator. This study evaluated positions of the PCL footprint using an image matching technique by in vivo six-degree-of-freedom (6-DOF) motion analysis for the natural knee joints. Average errors of this technique is within 1.0 mm for the translation, and within 1.0 degrees for the rotation. The PCL was divided into anterolateral (AL) bundle and posteromedial (PM) bundle anatomically. We report the length patterns of AL bundle and PM bundle in the squat activity. Subjects were the natural knee joints of four healthy men. The AL bundle becomes tense in flexion, the PM bundle becomes tense in flexion and extension by bone tunnel position. We showed the importance of bone tunnel position and the functional advantage of double-bundle PCL reconstruction.

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Hip Osteoarthritis (OA) is often caused by dysplasia and subluxation. Patients with severe OA are operated on total hip arthroplasty (THA). Impingement has been reported after THA and rotational osteotomy. Therefore, the functional assessment of hip joint has been investigated in many research groups. It is necessary that quantify the hip kinematics of the normal subjects and patients with severe OA. Therefore, this study aimed to perform motion analysis of hip joint. The image matching technique was performed determining the strength of correlation between the single-plane X-ray images and the computational simulated image from three-dimensional gray-scale model. The accuracy of this analysis method is within 0.3 mm and 0.3 degrees. In this report, we analyzed the extension activity from deep flexion and chair targeting six normal subjects and eleven OA patients. In both activities, the maximum hip flexion/extension of OA patients was significantly smaller than that of normal subjects, but the posterior tilt of pelvis at OA patients was bigger than that of normal subjects. The pelvis is tilted posteriorly for bending the femur, because the range of movement of OA patients is limited. In this study, we could be confirmed different kinematic patterns between normal subjects and OA patients.

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In the field of biomechanics is performed elucidating motion analysis of normal knee joints. These are not reported motion analysis targeting sports activity Therefore, this study performed in vivo six-degrees-of-freedom motion analysis for natural knee joints with high precision using an image matching technique. The image matching technique was performed determining the strength of correlation between the X-ray images from a flat panel detector and the computational simulated image from three-dimensional gray-scale model reconstructed using computed tomography. In this report, we analyzed six-degrees-of-freedom motion of golf swing activity targeting five normal knee joints. From the results of six-degrees-of-freedom motion, the maximum external angle of knee joints was confirmed about 14 deg degrees at back-swing, and the maximum internal angle was confirmed about 23.1 deg degrees at end of follow through. In the trajectory of transepicondylar axis, pivot was moved to central, medial, and lateral. We could be observed different kinematic of normal knee in golf swing by this technique.

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Biomechanical simulations of knee joint have been performed by using incomplete knee model or applying unreal load conditions. To overcome the problems in the conventional approaches, in this research, the lower limb model including cartilage, meniscus, whole femur and tibia were constructed from images. The muscle forces during normal walking were predicated by inverse dynamic analysis based on the measurement of motion capture system. By introducing the near real muscle forces as load conditions into the finite element analysis for the whole lower limb model, the finite element contact analysis were performed for normal walking and reasonable results were obtained.

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A representative surgery of scoliosis is the posterior correction and fusion using spinal fixation device. The aim of this study is to evaluate usability of minor diameter rod for spinal fixation device. Lumbar finite element (FE) models from the Ll vertebra to the L5 vertebra with segmental pedicle screw fixation were reconstructed. Four rod diameter in spinal fixation device were used. Two types of loading conditions were evaluated, including flexion and lateral bending under preload with 200N of axial compressive force on the superior surface of the Ll vertebra. The inferior end surface of the L5 vertebra was assumed to be fully constrained. As a result, it was found that von Mises stresses in the minor rod diameter of spinal fixation device were lower than the fatigue strength of titanium alloy.

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When culturing microalgae, we often use aeration for mixing the culture fluid. However, it is not clear how microalgae and aeration interact each other. In order to understand transport phenomena in a microalgae suspension, it is important to clarify the distribution of cells in a container. In this study, we visualized the distribution of microalgae in a tube container with aeration. In the case without aeration, we observed the bioconvection with chaotic pattern. In the case with aeration, on the other hand, we observed cells aggregated in specific regions.

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We have been investigating how to use microorganisms for bio-micromachines. We succeeded to control the motion of the protists such as paramecia, euglena, tetrahymena, etc., using their galvano-taxis and phototaxis. In the case of bacteria, however, the motion control using their taxis is difficult and only the successful example is using magneto-taxis for the special bacteria that contains magnetic powder in their body. In this study, therefore, we investigated how to control normal bacteria such as Bacillus subtilis and Lactobacillus using their chemotaxis. The most difficult point to make a motion control system using chemotaxis is that once we sprayed the chemical substances for control, how to erase this effect in the next control. We thought the neutralization is suitable if we use acid/alkaline as a spraying substances. First, we investigated the basic reaction of Bacillus subtilis to the acid and the alkaline solution. Generally, Bacillus subtilis is thought to prefer neutral (pH7) circumstance. Our results, however, showed that Bacillus gathered to the acid. Next, we made a chemical substance spraying system by modifying the inkjet printer. By using this system, we can make/disappear the bacteria group.

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Although we inhale air including virus and bacteria, these harmful substances are trapped on the surface of tracheal lumen and transported toward larynx from the trachea by ciliary motion. In this study, we investigated cilia-generated flow and ciliary motion in detail by changing the viscosity of mucous layer. In order to elucidate the effect of viscosity on the flow, we measured ciliary beat frequency (CBF). We found that CBF decreases as viscosity of mucous layer is raised. We then measured the motion of tracer particles in the fluid by a micro-PTV system. The mean flow velocity increases up to at the viscosity of 2.8mPa・s, but it decreases in high viscosity regime (>2.8mPa・s). These results illustrate that ciliated cells can generate directional flow even in the highly viscous conditions.

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It has remained unclear why birds with airsacculitis go into respiratory distress. Here the mechanism was elucidated by numerical simulations with a 1D electrical circuit of avian respiratory flow. The results demonstrated that thickening of the air sac wall caused anti-synchronization between an elastic recoiling force of the air sac walls and an intra-pleural pressure, bringing difficulties in expansion of air sacs to draw in airs during an inspiration period and thereby decreasing air to be pumped out during an expiration period. This was reflected in a decrease in air flow volume in parabronchi where gas exchange takes place. Therefore, it was concluded that airsacculitis causes imbalance in air flow dynamics in the avian lung and thus impairs breathing ability of birds.

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The optimizing simulation for swimming motion of an octopus-inspired propulsion mechanism was conducted in the present study. The body geometry of mimic octopus was put into the model. Based on the actual video of a swimming mimic octopus, the joint angles of the arms were determined. From the determined results, A-shaped and reverse N-shaped motions were extracted as two base motions. The magnitudes of these two motions were used as the design variables for the optimization. The swimming speed was used as the objective function. The particle swarm optimization (PSO) was used as the optimizing algorithm. From the results of optimization, it was found that the tips of the arms pointed forward in the recovery stroke when the range of motion was increased. This motion was considered to contribute increase in the thrust. It was also found that the arms were spread largely when the maximum joint torque was increased.

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The present research focuses on the dependence of Reynolds number on propulsion of swimming fish in three-dimensions. Our previous researches of two-dimensions have indicated that a fish speed can be modeled as the combination of thrust part and drag part. The model can be also applied to three-dimensions, thus, it is also found the thrust is almost independent of Reynolds number, but the drag becomes small with increasing Reynolds number.

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This paper reports on measurement of ground reaction forces (GRFs) of ant legs during running on level ground, vertical wall and ceiling. Micro force plate array is designed and fabricated to measure anterior and vertical directional forces. Thus, GRF of all legs in the various ground angles can be detected simultaneously. The size and force resolution are 2000 μm × 1000 μm × 20 μm and 1 μN, respectively. The measurement results show that ants use different GRF distribution in three types of terrestrial locomotion. In every types of locomotion, the ant was affected by the gravity reaction force, which was totally equal to the body weight. The gravity reaction force was approximately equal to each leg during running on level ground and ceiling. The gravity reaction force during ceiling was thought to be generated by the adhesion force of sub-micron scale hairs on the tip of the legs. The measured GRF distribution clarified that ants use the different strategies of running mechanism depending on the angle of the ground against the horizon plane.

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The goal of this research project is to investigate the relation of central nervous system and body balance function by testing the postural maintenance performance of a knock-out mouse. In the development of the prototype mouse stabilometer system, postural maintenance performance was evaluated and analyzed by measuring the variance of the stress on the pillar with strain gauges. However, with the stage swinging during measurement, the evaluated signal is affected by the inertia of the stage, and requires repeated trials to gain determinate data. Furthermore, without gaining the data on actual body mass movement, the relation of brain function and posture control remains non-committal. Therefore, the technical target is set to compute the center of gravity by applying a mechanical system model of the mouse and device to evaluate the postural maintenance performance. As to improve the prototype device to measure the amplified strain gauge signal with the A-D converter, the design of the pillar was adjusted to maximize the variance within the measurement range of the converter. The influence is simulated and the Center-of-Mass & Strain-gauge distance and Stage-surface & & Strain-gauge distance were modified.

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Dolphins are aquatic organisms with high swimming ability and propulsive performance. However, it has not been solved why they realize their high performance. In addition, it is not possible to measure the propulsive force directly generated by a swimming dolphin. Tail flukes have been considered to play an important role in high speed swimming. The tail flukes deflect by the hydrodynamic force passively. We thought the propulsive force of a dolphin could be estimated by using the relationship between the deflection of the tail fin and the fluid force acting on it. The objective of our study is to estimate the propulsive force of dolphin by using the mechanical properties of the tail fin. The bending properties of the tail fluke were examined experimentally in this paper. It was found that the flexural rigidity of the tail fluke increased as approaching to the end of the tail fluke.

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Fast swimming of dolphins has fascinated biologists and engineers for decades. Power output performance of dolphins is still a controversy topic till now, which is well known as the "Gray's Paradox," because it yet remains as a challenging problem of accurately estimating fluid drag / thrust acting on the realistic body of dolphins by quantifying its three-dimensional geometry. Here we reconstructed a realistic dolphin model by measuring an at-scale replica of a dolphin using a three-dimensional scanner. We then built a computationbal fluid dynamic (CFD) model and conducted a CFD analysis to compute velocities and pressures and hence calculate hydrodynamic drag forces of the dolphin. Our results demonstrated that the pressure drag component of the dolphin model was much larger than that of a simplified hyrodynamic model when the swimming speed reached maximum. Furthermore the estimated mass-specific power of the dolphin (84.0 W/kg) also showed larger value than that of the simplified model (51.3 W/kg). These results suggest that accurate three-dimensional geometry may play an important role in influencing hydrodynamics and should be considered in analysis of dolphin fast-swimming.

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In recent years, a swimming method of aquatic animals attracts attention as a high efficient propulsive one. Especially a dolphin is known as a fast swimmer. So we paid attention to a propulsive method by oscillating a tail flukes of the dolphin. A tail fin is the solo propulsive device of the dolphin. The structure and the mechanical properties of the tail fin affect the swimming behavior of the tail fin. The aim of our study is to develop a dolphin tail-like oscillating wing as a propulsor. The mechanical properties of the wing using CFRP sheets were investigated. The flexural rigidity of the wing was compared with that of tail flukes of the dolphin.

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The conventional screw propeller is widely used to propel boats and underwater vehicles. Recently, the use of a bio-inspired oscillating elastic fin has been proposed as an alternative propulsion mechanism in water. It is thought that the new mechanism will improve efficiency and safety, relative to the screw propeller. The optimum elasticity of the fin is not constant and changes based on swimming speed and task. However, it is very difficult to exchange fins of different stiffness while moving. We have developed a propulsion mechanism using a variable stiffness fin with torsional rectangular elastic plates. In this study, we made a model boat to provide basic data for the development of the boats and autonomous underwater vehicles using the variable stiffness fin. In this paper, we examined the propulsion characteristics of the model boat using variable stiffness fin with crescent wing compared to the model boat using the previous rectangle variable stiffness fin.

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This study is concerned with air damping effect in passive pitching motion of insect flapping wing, which will be based on the Fluid-Structure Interaction (FSI). Thus, we evaluated it using three-dimensional numerical analyses for the FSI based on the finite element method. From the numerical analysis, we found that the air damping leads the mode of wing's natural vibration from underdamping to overdamping so as to form the characteristic pitching motion.

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Dragonflies show unique and superior flight performance than other species of insect and bird. Dragonflies move their wings twist feathering motion when they fly. They can fly highly, stop suddenly, turn sharply, or whatever by changing their feathering motion. We observed dragonfly's straight flight and hovering, and we found difference of feathering angle between their straight flight and hovering. In this study, we made flap experimental equipment which can change its feathering motion, and we measured lift and thrust forces by using it. Moreover, we also visualized around wings of the flap experimental equipment by using baby powder, and we observed velocity of powders with Particle Image Velocimetry (PINT) measurement software. From experimental results, value of lift and thrust and backwash were varied by changing the feathering angle of the wing. Consequently, it was found that dragonfly controls the lift and thrust by changing the feathering angle of the wing.

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Flapping-wing small flying robots inspired from natural flyers have a potential for high maneuverability and high aerodynamic performance in low-Reynolds-number flow regime. To generate sufficient aerodynamic force in hovering flight, the wings should not only flap but also feather (rotate around the spanwise direction) in order to maintain appropriate angle of attack. The feathering motion is typically realized by passive torsion of the wing film in conventional flapping-wing robots. Here we propose a new wing structure which utilizes the passive feathering more actively. A hinge part was inserted at the wingbase of the wing, allowing an overall feathering rotation rather than the torsion of the wing surface. We compared four types of hinges with different maximum feathering angle using a tethered single-wing flapping mechanism driven by an electric DC motor. The wing shape and flapping motion were similar to those of hummingbirds. As a result, both generated vertical force and power consumption decreased with the maximum feathering angle of the hinge. Efficiency represented as vertical force per power consumption, however, was maximized by choosing the hinge with small feathering angle, in this case, 10 degrees. These results suggest that aerodynamic efficiency can be optimized by utilizing passive feathering rotation at the wingbase, resulting in reduction of mass proportion of a battery.

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This paper describes a biomimetic jumping mechanism, comprised of coil spring and electromagnetic switching system. The jumping movement of beach fleas was analyzed with a high-speed video camera system, and jumping organ was observed by using of a laser scanning microscope. Based on the jumping motion analysis and observation of jumping organ of beach flea, a simple jumping mechanism was designed and produced. The jumping characteristics of mechanism were also examined with the high-speed video camera system. It was found that the microtrichia morphology of jumping organ plays an important role for the extension of horizontal distance in mechanism jumping.

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Reduction of the mechanical loss due to friction between two surfaces in motion is necessary to use natural energy resources effectively. A biomimetic bearing with ability of water sealing was proosed to expect the reduction of the mechanical loss for use in micro-&cluster-generation Systems as water power generators. The components of the bearing with sealing system has a rotating shaft sliding on the counterface made of polyvinyl formal (PVF) lubricated by polyethylene glycol (PEG) solution. The PVF which has hydrophilic and coutinuous porous structure promotes the elastohydrodynamic lubrication and weeping lubrication that are observed within synovial joint. In this report, durabillity of the bearing is discussed. The PVF material with porous diameters of 700 μm was adopted for the counterface material for a rotating shaft of 20 rpm. A load of 100 N was applied perpendicularly to the housing of bearing system. Two PEG solutions, one of molecular weight 2 million and the other a mixture of 0.5 and 0.02 million, were adopted as lubricating liquids. A tensile test was carried out after the friction test. A PEG solution with a molecular weight of 2 million produced a much lower coefficient of friction when compaired to the mixed solution. The maximum tensile force of PVF did not change after the friction test, but the elastic modulus increased in comparison with that which was assessed before the frictional test. It is shown that the PVF bearing with a excellent duability for sliding distances as high as 25,000 m, and that the molecular chains of PVFs might orientate to frictional direction.

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Fundamental experiments have been conducted on the heat transfer characteristics of the thermosyphon fabricated on the plastic plate by using water and ethanol as the working fluid. The thermosyphon is the gravity-assisted thermal device to transport heat by utilizing the latent heat of evaporation and condensation of the working fluid; it works without any external power. In experiments, the temperature distributions of the thermosyphon with water and ethanol are measured respectively by changing the heat input and the liquid volume inside the thermosyphon. The experimental results are shown on the transient and the steady-state heat transfer characteristics of the thermosyphon. The discussion is also made on the difference between the cases of water and ethanol. Furthermore, based on the thermal resistance network model, the effective thermal conductivity of the thermosyphon is evaluated. It is confirmed that the heat transfer performance of the thermosyphon with water is better than that with ethanol in the present experimental range.

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This paper presents evaluation of effect of cell-cell adhesion and cell-substratum adhesion on cellular differentiation. A microwell array having convertible culture surface (CCS microwell array) is used for limitation of culture area and regulation of the adhesion timing. The CCS microwell array is fabricated by photolithography on the cover slip. The alginate thin film is used as a material that inhibits adhesion of cells. It can be removed by ethylenediaminetetraacetate (EDTA), which is calcium chelator, at arbitrary timing during cell culture. A single spheroid, 3D multicellular aggregate of cells, is formed by cell-cell adhesion in CCS microwells because cells can't adhere to the culture surface by adhesion inhibition effect of the alginate thin film. When the culture surface is converted to cell-adhesiveness surface by removing alginate thin film, cells adhere to the CCS microwell bottoms. The transition of the diameter of spheroid cultured in the microwell was evaluated. Also, we compared the differences of cellular differentiation behavior on the four kinds of conditions for verification of cell-cell or cell-substratum adhesion effect. We explained that cellular differentiation was able to be guided more efficiently than three kinds of other culture conditions by cell culture on the CCS microwell array.

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The purpose of this study is to find an efficient method to purify deep water in lake of the Midorikawa dam in Kumamoto. The biochemical oxygen demand (BOD) of the water at first was 46 mg/L in the worst case. In the test, microbubbles were periodically supplied into the water in 80 L test tank by a multi-fluids-mixer patented by Sadatomi and Kawahara. The aeration rate were set as Q_G = 1.0 L/min or 2.0 L/min to study its effects. In addition, a water quality improvement material containing aerobic bacteria was immersed in two tanks of the three in order to clarify its effects. As a result, it was found that Q_G = 1.0 L/min was enough to reduce the BOD to about 6-10 mg/L for ten days, and the bacteria material was effective to reduce the turbidity of the test water.

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Ultra-High Molecular Weight Polyethylene (UHMWPE) is widely used as a bearing material in artificial joints. However, UHMWPE wear particles are considered to be a major factor in long-term osteolysis and loosening of implants. Many researchers have reported that the volume and size of particles were critical factors in macrophage activation, with particles in the size range of 0.1-1 gm being the most biological active. To minimize the amount of wear of UHMWPE, and to enlarge the size of UHMWPE wear particles, a counterface material of Co-28Cr-6Mo alloy was processed using micro slurry-jet erosion (MSE). The slurry used in this analysis consisted of alumina particles mixed with water, which was then combined with compressed air within an injection nozzle. The slurry was ejected onto the Co-Cr-Mo alloy at a high speed to process a superfine surface. Four types of Co-28Cr-6Mo alloy surface profiles were prepared; M-1, M-2, and M-3 were processed by MSE. The feed rate of injection nozzle for processing of M-1 was 1mm/s. That for M-2 was 2 mm/s to reduce the MSE effect in comparison to for M-1. M-1 was lapped with nano-diamond to reduce the asperity on the surface, and the processed surface was represented for M-3. The conventional artificial joint surface was represented by G-1, which had a 10 nm surface roughness, as a control surface. A pin-on-disc wear tester capable of multidirectional motions was used to test if MSE processing was the most appropriate for artificial joints. It was found that the processed surface reduced the amount of UHMWPE wear, which would ensure the long-term durability of artificial joints. A scanning electron microscope was used to measure the size of the UHMWPE wear particles. A significant difference was not observed in the aspect ratio of the wear debris, and many wear particles greater than or equal to 1.0 gm in size were observed.

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This paper reports on design, making the FEM analysis model and testing of prototype hardness sensor for endoscopic application with the suction tube. This sensor was designed for a purpose of measuring the hardness of hematoma surface. It consists of an aspiration cylindrical tube made of silicon rubber and a rigid cylinder made of acryl. First, overview of the developed sensor system is presented. Next, fundamental characteristics of the sensor were examined by using the Fluid-Structural interaction FEM analysis. The results showed that the analytical values has corresponding with the theoretical values and the sensor can measure elasticity of clot surface.

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The contact angle varies during the movement of the contact line and exhibits very complicated behaviors. Even the wettability of a static droplet on a solid surface, the detailed mechanisms behind the wetting of the droplet remain unknown at present. In general, the wettability of droplet on a solid surface is characterized by Young equation which represents the thermodynamic equilibrium condition in the horizontal direction at the contact line. Surface force in the vertical direction at the contact line is generally ignored due to the resistance of the solid surface. However, recent numerical and experimental studies reveal the importance of the adhesion force in the vertical direction at the contact line. In the present study, an analytical model is developed herein by considering the energy balance including adhesion forces acting not only in the horizontal but also in the vertical direction. Then, the validity of the developed model is then evaluated by experimental observation of the wetting phenomena of droplets on low and high-surface-energy solids. The result indicates that our model can describe the wetting phenomena of droplets on low and high-surface-energy solids.

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Application of multiphase phenomenon in a living system to an engineering product is proposed in this paper. The material characteristics with hydrophilic and continuously porous structure, which mimics articular cartilage, were adopted for the seal lip in order separate between water phase and gas phase. The water sealing system for a rotating shaft could produce low friction and low ingress of water to mechanical system. The material characteristic with low elastic modulus was adopted for the load bearing material in order to produce shock adsorption against externally applied force. In the system, an externally applied electric field to bearing surfaces was proposed in order to control the frictional characteristic, in which the electric field produced the low shear layer lining on the bearing surface.

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