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Yuji SHIMOGONYA, Yohsuke IMAI, Takuji ISHIKAWA, Takami YAMAGUCHI
Article type: Article
Session ID: 1126
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The mechanism of the growth of cerebral aneurysm has not yet been understood. We focus on biological reactions in addition to purely mechanical process. We propose a simulation model to express the assumption that surface areas of the arterial wall are increased locally where wall shear stress value is much higher. We applied the model to a U-shaped artery with torsion. The resultant shape was consistent with clinical observations. It is concluded that it is necessary to consider biological reactions to understand the growth of the cerebral aneurysm.
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Mizuho MATSUBARA, Masao WATABANE, Satoshi WATANABE, Kozo KONISHI, Shoh ...
Article type: Article
Session ID: 1127
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Budd-Chiari syndrome (BCS) is one of the vessel disorders caused by thrombosis which occlude partially or completely hepatic veins (HVs) and the inferior vena cava (IVC). It has been demanded to model the blood flow fields in the IVC and HVs to study the cause of formation of thrombosis. In order to analyze the blood flow fields, we carried out medical vessel segmentation of HVs and IVC using level set method, constructed 3D vessel model, and conducted computational fluid dynamics simulation by using velocity profile of the analytical solution for pulsatile flow in the IVC.
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Makoto OHTA, Toshio NAKAYAMA, Chuan HE, Akira TAKAHASHI
Article type: Article
Session ID: 1128
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The cerebral arteries in rats are reconstructed and the blood flow dynamics are performed by micro-CT for investigating cerebral aneurysms such as mechanism of generation, growing, and rupture of aneurysm. The cerebral arteries in rats were extracted from the brain by using cast techniques. The 3-D reconstruction of arteries by micro-CT indicates the possibilities of computational flow dynamics (CFD). The contrast media was injected from the external carotid artery into the cerebral arteries. The blood flow flushing the contrast media in cerebral arteries observed by micro-CT may allow the trace of blood flow using the cinematic angiography method, if the time resolution increases.
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Kosuke IGA, Hiromu HASHIMOTO
Article type: Article
Session ID: 1129
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper describes flight motion photographs of Dragonfly's wing motion and airflow visualization around wing to develop MAV. It is very difficult to know aerodynamic characteristics, when the Dragonfly is flying freely in nature, by using the conventional visualization technology. Therefore we develop the motion photographic technique and visualization technology and then the Dragonfly's flying motion and visualization data can be obtained by using these techniques.
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Ryuichi ARITA, Kenkichi OHBA
Article type: Article
Session ID: 1130
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The purpose of this research is to elucidate the mechanism of lift generation and control in flapping flight of a mosquito. In this study, a tenfold enlarged realistic model of the flapping wing was used to simulate the motion of the mosquito's wing and flow pattern around it. Experiments were conducted using a very low speed wind tunnel to coincide the condition of Reynolds and Strouhal numbers with those of real mosquito. The flow field around the wing model was visualized using smoke and a laser light sheet, and was analyzed by a stereo-PIV system. In these experiments, we investigated the relationship between the flow field and the flapping angle. We found an unsteady ring vortex and a jet around the model wing. It was also found that the time-average of the lift was proportional to the square of flapping angle.
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Naoya OKAMOTO, Masahiro WATANABE, Hideaki TANAKA
Article type: Article
Session ID: 1131
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper deals with an experimental study on the self-excited flapping mechanism of tandem flexible airfoils which mimicked a light insect for a fluid in low-Reynolds number. For efficient drive, excitation mechanism with the natural frequency is needed. However, he natural frequency changes with increasing the amplitude. A self-excited driving system for flapping flexible airfoils is developed in his study. In the experiment, it is found that the propulsive force is changed by phase difference between the fore and hind airfoil because of the interactions between them.
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Daisuke ISHIHARA, KAZUYA Inoue, Tomoyoshi HORIE, Tomoya NIHO
Article type: Article
Session ID: 1132
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Hikaru AONO, Hao LIU
Article type: Article
Session ID: 1133
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We investigated the effect of wing rotation axis on an aerodynamic performance in insect flapping flight by a biology-inspired flight dynamic simulator. This simulator was developed to be capable of 'flying' an insect on a basis of realistic wing-body morphologies and kinematics. We carried out 11 case studies by changing position of origin of the rotational axis of a wing. The computed results indicated that the position of origin of the rotational axis of the wing affects significantly the lift force production over a flapping cycle. In particular, during supination and pronation, the adequate position of origin of the rotational axis of the wing can increase the lift force production.
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Na GAO, Hikaru AONO, Hao LIU
Article type: Article
Session ID: 1134
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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A numerical study of dynamic flight stability of a hovering hawkmoth is presented. The method of computational fluid dynamics (CFD) is used to compute the aerodynamic derivatives of the aerodynamic forces and pitching moment in response with a series of small disturbances and the techniques of eigenvalue and eigenvector analysis is used for solving the equations of motion. In the longitudinal disturbance motion, three natural modes are identified of a stable oscillatory mode, a stable fast subsidence mode and a stable slow subsidence mode, which indicate that the hawkmoth hovering flight is stable. In short, a hovering hawkmoth, if the motion is dynamically stable and the disturbance die out fast, might not need to make any adjustment with wing motion and will return to the equilibrium state 'automatically'.
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Hiroshi Hosoya, Motoyoshi Ohaba
Article type: Article
Session ID: 1135
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The oscillatory responses of a single leaf of sweet potato are examined under lighting by a fluorescent light in a uniform airflow. The leaf displacement is measured using a laser displacement detector, and the corresponding power spectrum density of the data is calculated. The equilibrium shape of the leaf is changed as a function of time. The primary resonant frequency of the leaf has shifted to higher value, and its magnitude of the power spectrum has also increased during the course of experiments. These dynamic responses are due to the deformation of the leaf shape by the phototropism. These responses also suggest the influence of the airflow, because the evaporation from the leaf is activated.
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Masao Yokoyama, Osamu Mochizuki
Article type: Article
Session ID: 1136
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We investigated the deformation of a soft structure filled with a liquid in a uniform flow by solving a coupled problem. The liquid inside was the same as that of the outer flow in this study. The soft object was modeled by a circular cylinder whose surface was made of a network of mass-spring-dumper system to represent its mechanical characteristics. The soft structure was deformed from the circular cylinder due to inside and outside forces acting on the surface. We found that the soft structure became ellipse-like cylinder whose major axis was perpendicular to the main flow direction. The ellipticity depended on the value of the spring constant or damping coefficient. We discussed the effects of a spring constant and damping coefficient on the deformation.
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Kenichi AKANISHI, Kenkichi OHBA
Article type: Article
Session ID: 1137
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Fluttering is a self-excited oscillation which happens with a slender object in flow. We have investigated fluttering characteristics of a flexible sheet in uniform water flow using a silicone rubber sheet and a vinyl sheet. The cross-sectional shape of the sheet in flow was visualized by a laser sheet method and its behavior during fluttering was photographed by using a high speed video camera. The frequency, wavelength and amplitude of traveling-wave on the sheet during flutter were analyzed from the visualized images. Additionally, flow-fields around the sheet during fluttering were visualized.
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Hiroyoshi SUZUKI, Naomi KATO
Article type: Article
Session ID: 1138
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper describes the use of a three-motor driven mechanical pectoral fm as a device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fm consists of three servomotors generating feathering, rowing, and flapping motions. The time varied hydrodynamic force properties of three types of fin motion and two kinds of fluid circumstances were measured. Measured data is useful for validation or verification of CFD or some numerical methods in case of estimating hydrodynamic force generated by a pectoral fin.
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Hirofumi INOUE, Kensuke KIRIMOTO, Shigeru NISHIO, Masafumi OOTANI
Article type: Article
Session ID: 1139
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The mechanism of propulsive force generation of fishes in quick start motion was analyzed by means of hydrodynamic force measurement and the velocity field measurement. A waving wing model was used for the experiments, and the time series velocity field was measured by PIV system. The small change of wing motion sometimes causes large difference of thrust force, and it depends on the interaction between the wing motion and the wake of the last swing motion.
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Yogo TAKADA, Toshiaki TAMACHI, Yoshinobu NAKANISHI, Ryosuke ARAKI, Tom ...
Article type: Article
Session ID: 1140
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The velocity distribution of water flow around a real swimming fish has been measured by PIV and analyzed by CFD in order to create new aqua-robots which can swim like a living fish or dolphin. A flexible fish robot with 2 motor-string actuators was created. If the inner part of tail fin was adequately softer than the outside of that, the fish robot was able to swim fast. It has been shown by PIV measurement that this fish robot with a latex rubber tail fin generates the reverse Karman vortex street as a real swimming fish does. In addition, the authors created a swimming humanoid robot which swam like a dolphin. This swimming robot was able to swim in various ways and the operation sequence of servomotors for better swimming was acquired by the particle swarm optimization (PSO).
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Tomoki TERASHIMA, Ryohei MORISAKI, Shunichi KOBAYASHI, Hirohisa MORIKA ...
Article type: Article
Session ID: 1141
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We have made the multilink propulsion mechanism in fluid modeled on anguilliform swimming. This propulsion mechanism can be applied to the manipulator and the amphibian propulsion mechanism. In this study, we improved the mechanism to swim in highly viscous fluid of muddy water, and discussed the propulsion characteristics with changing properties of muddy water, movement pattern and fin of the mechanism.
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Tetsuya YOSHIIKE, Yusuke OKUMURA, Hirohisa MORIKAWA, Shunichi KOBAYASH ...
Article type: Article
Session ID: 1142
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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A propulsion system with a fish-like tail fin stroke has been proposed as a novel propulsion system with higher propulsive efficiency and higher safety than a conventional screw propeller. This paper describes the development of an outboard propulsor using an oscillating horizontal fin that is easy to attach to and detach from a small boat. The performance of the outboard propulsor mounting a reflection panel over the fin was investigated. In the experiment, the velocity of the boat, the acceleration and the fuel cost were measured by using a rigid fin and an elastic fin. The thrust of the outboard propulsor was estimated by obtaining acceleration of the moving boat.
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Masayuki KIKUDA, Yuichiro KURODA, Tonau NAKAI, Tomonobu GOTO
Article type: Article
Session ID: 1143
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The influences of a rigid surface and a free surface on the motions of singly flagellated bacteria have been investigated. The motions of backward swimming cells are significantly changed by the two surfaces while the forward swimming cells are rarely affected. Both of the surfaces influence the velocity in a similar manner as well as the trajectory, although the quantitative effects of the two surfaces are different. The trajectory of the backward swimming cells near a rigid surface comprises circular parts. Similar circular parts have been observed in the trajectory near a free surface. The velocity of the backward swimming cells either near a rigid surface or near a free surface is higher than the velocity in a free space. However, the curvature and the velocity appeared near the rigid surface is bigger and higher than the curvature and the velocity near a fine surface, respectively. Forward swimming cells tend to draw a rectilinear swimming trajectory irrespective of the surfaces. T velocity of the forward swimming cells near a rigid surface or a free surface does not differ from the velocity in a free space.
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Takaaki SATO, Hitoshi MIYAKE
Article type: Article
Session ID: 1144
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The muscle spindle, that is a sensor in vivo, has an interesting structure. To combine an actuator and a sensor develop a unique sensor system, a linear stage and a tensiometer was combined for a prototype tensiometer. But it was not perfect muscle spindle mimeties, and it had necessity, to compare both the control theory of the muscle spindle and artificial muscle spindle. So the control block diagram difference between the tensiometer and the muscle spindle was compared in this study.
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Nobuo Sakai, Go Yamaguchi, Yoshinori Sawae, Teruo Murakami
Article type: Article
Session ID: 1145
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The purpose of this study is to develop the scapula mechanism for the robotic shoulder model. Human shoulder has the largest motion range in human musculoskeletal mechanism. So-called 'Shoulder' consists of Humerus, Scapula, Clavicle and Thorax. Scapulo-humeral joint has a ball joint mechanism that moves in 3-degrees of freedom in single joint. Scapulo-thoracic sliding extends a range of motion of the ball joint and stabilizes upper limb with Scapulo-clavicle joint. Authors thought that the shoulder girdle complex is one of the adequate mechanisms to construct compact and lightweight joint system for living body. In previous paper, authors reported the development of the robotic Scapulo-humeral mechanism that had the ball joint mechanism and was driven by 6 wires. Consequently, authors tried to develop the Scapulo-thoracic articulation mechanism to reveal harmonic motion of shoulder complex. This paper describes the development of the Scapula mechanism robot. Muscles for actuating Scapula were substituted by wires according with anatomical literature and Thorax was reduced to a sphere surface. The scapula part was stabilized by the clavicle part in which the proximal joint of the clavicle part was connected to the breastbone position. The movability in this mechanism was confirmed by estimation of moment arm, and the Scapula part was driven by 8 wires as a robotic system successfully.
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Takahiro OGURA, Koji TAJIMA, Akitoshi ITOH
Article type: Article
Session ID: 1146
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In this research, the possibility of motor-spring series connection type biomimetic actuator was investigated. The motion of the joint angle is controlled by two D.C. motor through each spring. The actuator has one powered joint (knee) and two free joints (ankle and hip). The both free joints of the actuator was attached to the spline shaft. The control method how to make jumping and soft landing by this actuator was investigated. The optimal continuous jumping sequence was investigated based on the optimal sequence of bending and stretching jumping. It is necessary to make the landing posture during the "in the air" term. Direction reversing timing have to be adjusted by the previous jumping height. The both of the mathematical simulation and the experimental results show that this optimal scheme increase the jumping hight.
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Tomoyuki SAITO, Tadao KAGIWADA, Hiroyuki HARADA
Article type: Article
Session ID: 1147
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We developed an earthworm robot that is made from a shape memory alloy called BioMetal (trademark of TOKI CORPORATION) and uses polyester braided tube as an actuator. BioMetal is a current-driven type fiber-like solid-state actuator which is structured by special fabrication method from a Ti-Ni shape-memory alloy. We used BioMetal Helix (BMX) series to get contraction force. It becomes stiff like a piano wire and sharply contracts 100-200% of the lebgth, when current fed through it. If the passage of a current is stopped, it becomes soften and extends to its original length. To get extension force, we use polyester braided tube. It spreads to between 1.5 and 4 times its width under pressure. It is used to protect wires essentialy, but we aimed at the extension force to recover oridinal width. Finally, we realized a motion like earthworm by connecting four flexible units and controlling flexible timing by the microcomputer.
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Yoshikata Muguruma
Article type: Article
Session ID: 1148
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper describes a new vehicle for child. This is invented from Animals-movement (fish and lion and bird) Running-Zabuton has wheels moving like fish-tail, stand by 4 legs like Lion and propel itself by wind like bird.
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Shouji KUZUKAMI, Osamu KUWAZURU, Nobuhiro YOSHIKAWA
Article type: Article
Session ID: 1201
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We have proposed the full-field digital image correlation for three-dimensional displacement field. The displacement is tentatively defined in the correlation domain of the undeformed state image data by using B-spline basis function. The flat intensity distribution of image data yields the ill-posed problem through the correlation process. The incompressibility constraint is set on the formulation to cope with the solution indeterminacy. The modified objective function of minimization, containing error function of correlation, is derived in line with the penalty function method. The iterative technique of the Levenberg-Marquardt method is employed for the search of the non-linear stationary condition of the modified objective function. The Green-Lagrange strain field is directly calculated by the derivative of identified continuous displacement field. An error in strain field caused by digital property of image data is investigated by using artificial deformation data corresponding rigid translations.
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Keisuke HAYABUSA, Kenji AMAYA
Article type: Article
Session ID: 1202
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Masataka TANAKA, Youri ARAI, Hisashi HAYASHI
Article type: Article
Session ID: 1203
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper is concerned with optimal shape design of a noise barrier in acoustic problems, which are in a 2D half sapce. It is desired that the optimal barrier shape with a large noise reduction can be found though thid study. The present paper proposes a procedure for a noise barrier problem in which the new boundary element method and a genetic algorithm (GA). Through numerical computation of typical examples is demonstrated the usefulnessof the proposed procedure.
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Atsuhiko SENBA, Kaoru OHASHI, Hiroshi FURUYA
Article type: Article
Session ID: 1204
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This study presents experimental results of parameter identification of a conceptual variable geometry truss model, which consists of nine variable length members for changing geometry of truss structure. All the variable members are changed uniformly so that the total length of the truss is changed, and the first natural frequency is changed accordingly. The change of the natural frequency due to geometry changes indicate that the structural parameters can be identified using the relation between the length of the variable members and natural frequency of the truss, thus the system has an capability of self-identification. Basic experiments are conducted using the variable geometry truss to investigate the feasibility of the present method, and the results show that unknown structural parameters such as additional mass attached at the end module of the truss can be identified by using the first natural frequencies corresponding to some different geometries.
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Ryuji ENDO, Nobuyoshi TOSAKA, Akira Satoda
Article type: Article
Session ID: 1205
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Variable parametric projection filter (VPPF) is proposed as inverse analysis procedure to identify the system rigidity and water level of cylindrical shell structure. Parametric projection filter has known as effective filter in compare with Wiener filter and projection filter. As the characteristics of the parametric projection filter, the regular parameter to assure the stable filtering process is including. The regular parameter has been given as a voluntary value corresponding to each inverse problem in the existing analysis concerned with inverse problem using filtering algorithm based on parametric projection filter. In this study, the procedure to give the regular parameter computationally in each filtering step is shown instead of a voluntary value. Effectiveness of the VPPF is shown though some numerical calculations based on the previous problem.
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Kazuhiro SUGA, Masato YOSHIDA, Shigeru AOKI
Article type: Article
Session ID: 1206
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This study proposes a monitoring method for corrosion on reinforced concrete structure using inverse analysis approach. We define an inverse problem to identify the real part and imaginary parts of the concrete conductivity and the impedance between concrete and steel. The observation of the inverse problem is the electric potential on the concrete structure surface when the AC impedance measurement is performed. The observation condition, such as layout of observation point and type of observation, of the inverse is optimized. The optimization is achieved by minimizing the average of eigen values of a posteriori estimate error covariance matrix based on the Kalman Filter estimation algorithm and by sensitivity analysis of observations.
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Kota FURUKAWA, Shiro KUBO, Takahide SAKAGAMI
Article type: Article
Session ID: 1207
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The passive electric potential CT (computed tomography) method was applied to the identification of Z-shaped delamination existing in composite material. The electric potential distribution on piezoelectric film pasted on composite material is influenced by delamination parameters. The identification of delamination parameters from electric potential distrubution is an inverse problem. We proposed inverse analysis scheme for identifying delaminations and showed its applicability. The electric potential distribution for mountain-shaped array of delaminations was examined.
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Masafumi ITAGAKI
Article type: Article
Session ID: 1208
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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To reconstruct the current density profile in tokamak plasmas, an inverse analysis method is under development. In the analysis, the boundary integral equation for a polynomial expanded current is coupled with several constraints. Recently, (i) the method of transformation from measured poloidal field values inside the plasma to current density has been improved. (ii) The "generalized cross validation" has been introduced to estimate the optimized value of the Tikhonov regularization parameter. (iii) A new method to apply the equilibrium condition has been added to the analysis. Due to these improvements, the reconstructed results are quite accurate for parabolic plasma, roughly agree with the reference values for other types of plasmas.
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Takuya ISHIZAKA, Shiro KUBO, Seiji IOKA
Article type: Article
Session ID: 1209
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In this paper a multiphisics inverse method is proposed for determining the optimum thermal load history of a thick-walled pipe which reduces transient thermal stress under start-up considering the multidisciplinary physics. The multidisciplinary complex problem was decomposed into a heat conduction problem, heat transfer problem, and thermal stress problem. A numerical solution of the temperature distribution of the radial thickness and the thermal hoop stress distribution was obtained by using the finite element method. The maximum inner hoop tensile stress was minimized for the case where inner surface temperature T_S(t) was expressed in terms of the 3rd order polynomial function of time t. From the temperature distributions, the optimum fluid temperature history was obtained for reducing the transient thermal tensile stress.
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Kouki NISHIYAMA, Shiro KUBO, Seiji IOKA
Article type: Article
Session ID: 1210
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We developed the method to inversely estimate coefficient of heat transfer from results of temperature measurement. We selected a thin-walled pipe as an analysis object, and selected fluid temperature in the pipe and temperature outer surface as measured value. We proposed inverse analysis to estimate history of temperature in the pipe wall, heat flux inside the pipe and coefficient of heat transfer between the pipe and fluid. The influence of temperature measurement errors on the estimation was discussed.
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Masashi HANAKI, Hiroyuki FURUKAWA, Takashi WATANABE
Article type: Article
Session ID: 1301
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Taylor vortex flow appears between two concentric rotating cylinder for example, fluid bearings of hard disks, journal bearing and chemical reaction container etc. It is important for engineering to clarify the behavior of Taylor vortex flow In this study, the initial flow distributions between two rotating cylinders are changed, and the effects of the initial condition are examined. As a a difference was observed in the final mode depending on the difference of the initial flow condition. However, no regularities regarding the difference in mode formation were found and the tendency of the mode formation process was not specified. The processes of developing the vortex resulting in different final modes were monitored over time by visual observation. There was also a difference in the time taken for the flow to reach the steady state. In each mode formation processes, kinetic energy is compared.
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Toshiki MORITA, Takashi WATANABE, Yorinobu TOYA
Article type: Article
Session ID: 1302
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We performed numerical computations of Taylor vortex flow at small aspect ratio. When the flow develops from its initial state at rest, non-unique flow patterns appear, which depend on the lengths of the cylinders and/or the final Reynolds number. In experiment, it is difficult to keep constant conditions because of the imperfection of the apparatus and the small disturbances of the flow field. Therefore, the experimental result may show its inherit variations. In this study, we focus our attention on the small fluctuations of flows. Two-dimensional numerical simulation is used to estimate the effect on the final modes of Taylor vortex flow. Statistical analysis of the results presents a favorable agreement with our prescribed experimental result.
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Shigeru Obayashi
Article type: Article
Session ID: 1303
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Data mining technique based on Rough Set theory has been applied to solutions obtained from three-objective optimization for regional jet wing design with engine nacelle. To reveal design tradeoffs, multiobjective optimization was performed by using Evolutionary Algorithms coupled with the Kriging model. High dimensional data (design parameters and the corresponding objective function values) are mapped onto the two-dimensional Self-Organizing Map (SOM) where global tradeoffs are visualized. The rule sets are derived by Rough Set theory so as to determine the importance of design parameters corresponding to the clusters obtained from SOM.
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Shigeru Obayashi, Shinkyu Jeong, Takashi Shibasaki
Article type: Article
Session ID: 1304
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Large amounts of data regarding various physical phenomena can be acquired from CFD analysis of unsteady flow field. However, the post-process of the unsteady CFD data is usually performed by averaging each time-step data or by searching eventual correlations among points in the flow field. In those cases, most of the unsteady CFD data end up being unused. The objective of this work is to construct a Data Mining method for the post-process of unsteady CFD data. The Data Mining method in this study consists of a time-series analysis and a cluster analysis. The time dependent flow characteristics are extracted by the time-series analysis, while the features regarding space are extracted by the cluster analysis. The Data Mining method was applied to unsteady CFD data of base flow at transonic speed and it successfully captured instability of shear layer, shock wave and vortex shedding.
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Kazuyuki SUGIMURA, Shigeru OBAYASHI, Shinkyu JEONG
Article type: Article
Session ID: 1305
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We applied data mining techniques (Decision Tree Analysis and Rough Set Theory) to an optimal design database in order to extract useful design rules. The database was created using data obtained by solving of a four-objective aerodynamic optimization problem for a centrifugal fan, in which three types of aerodynamic efficiencies and the turbulence noise level were optimized. The extracted rules are expressed in "if…, then…" form and can be used by designers to make decisions. We demonstrated that these data mining techniques can be used to select important design variables applicable to various design objectives. While Decision Tree Analysis derives a single statistical rule, to which the most sensitive design variables are related, Rough Set Theory derives multiple rules, with which even non-linear interactions among design variables can be taken into account. We confirmed that using several data mining techniques is necessary for correct understanding of the design problem.
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Shumei KAMEYAMA, Makoto Uchida, Susumu SHIRAYAMA
Article type: Article
Session ID: 1306
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Network-type data increases in engineering information, since information becomes to be structured by hyperlink. In order to extract knowledge from such data, many methods to detect cluster structure in network-type data have been developed. However, it is difficult to classify or identify the clusters detected in the network-type data, and such clusters are not sufficiently exploited. In this paper, we propose a method for identifying clusters detected by a certain clustering method. One of the clustering methods is utilized to divide a network-type data into clusters. The clusters are identified by another clustering method.
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Ikuo NAKAMURA, Takashi WATANABE, Hiroyuki FURUKAWA
Article type: Article
Session ID: 1307
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Explanation has a fundamental importance for communication in the society and we can understand a flow field which is explained by some natural language. We discuss some aspects of the roll of "vortex" in the explanation of flow by referring drafts of Leonardo and his sketches.
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Ryosuke ARATA, Yuriko TAKESHIMA, Shigeo TAKAHASHI, Issei FUJISHIRO
Article type: Article
Session ID: 1308
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Simulated/measured datasets are frequently time-varying as well as multi-dimensional and multivariate, and thus are too difficult to be analyzed. Topological feature analysis is one of the promising approaches to visualizing such datasets effectively and efficiently. In this paper, we attempt to extract ridge/ravine circles to identify regions of interest from target scalar fields associated with time-varying 2D flow fields. A case study with simulated datasets for Karman vortex street is performed to illustrate the feasibility of the present method.
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Akira EGAWA, Susumu SHIRAYAMA
Article type: Article
Session ID: 1309
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Annotation has played an important role to communicate user's experience or knowledge to another user. Adding such annotation to visualized computational results in CAE has not been adopted owing to convincing users that images visualized by a user represent some knowledge itself. However, as complexity of computational data increases, interpretation of visualized results becomes more difficult, and expertise annotation is of nessecity requiered. In this paper, we propose an effective annotation method for images from CAE to support the easy interpretation of the results First, we examine user's viewpoint on a certain image to be interpreted, through eye movement analysis or mouse movement analysis. Second, characteristic features of viewpoint movement are extracted, and pattern of viewpoint dependence is inquired using a picture of the "attention map" and a chart of time variation in movement of attention point. These are added to the result as annotation.
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Issei FUJISHIRO, Yuriko TAKESHIMA, Toshiyuki HAYASE
Article type: Article
Session ID: 1310
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In this paper, we present the prototype of a novel cooperative visualization environment, called VIDELICET (<VI>___-sualization <DE>___-sign and <LI>___-fe C__-yclE__- managemenT__-), and explore datasets from transdisciplinary fluid integration research to illustrate the effective usage of the system.
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Susumu SHIRAYAMA
Article type: Article
Session ID: 1311
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Owing to the volume of data generated in recent computations and experiments, it is quite difficult to extract useful information from these data even if using scientific/information visualization techniques. Method or methodology to extract useful information from such data should be considered. Several concepts of very large scale visualization are proposed in this situation. Most of them are based on high-performance computing techniques or highly-efficient devices for computer graphics. In this paper, a flexible visualization methodology based on "analysis of visualization process" is introduced. A possibility that a visualization agent designed from a process model helps to reduce the difficulty of handling huge data is described.
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Takeshi INOUE, Hiroaki NAKAI, Tetsusei KURASHIKI, Masaru ZAKO
Article type: Article
Session ID: 2319
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The bolt made of GFRP, which guarantees the properties such as sufficient electric insulation, is utilized as one of joints. It is important for the design of joint to check the stress distribution of bolt thread and to evaluate the fatigue characteristics. The purpose of this study is to evaluate fatigue characteristics of GFRP bolt by an analysis considered with anisotropic properties of failure modes. In particular, the results of FEM analysis have been reflected the failure modes of fatigue tests. The stress distributions along the bolt thread made by GFRP differ from traditional those. It is revealed that the differences of the stress and the strength cause the complex failure modes.
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Toshio HATTORI, Minoru YAMASHITA, Naoya NISHIMURA
Article type: Article
Session ID: 2320
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Fretting fatigue process have many features such as early stage crack initiation at contact edge, very slow crack propagation and fatigue failure after very long life operation. In previous paper we present new fretting fatigue model which can explain these fretting fatigue features reasonably. In this paper we try to explain other many fretting features such as fretting fatigue strength and life dependence on contact pressure, contact edge shapes. Firstly we try to discuss the dependence of fretting fatigue strength/life on contact pressure. In accordance with the increase of the contact pressure the stress concentration at contact edge increase and crack initiation stress level decreased. But to open this small cracks initiated at contact edges more wear or more load cycles are needed. So fretting fatigue strength limit decrease in accordance with the increase of contact pressure and fretting fatigue life increase in accordance with the increase of contact pressure. Then we discuss the fretting fatigue strength dependence on contact edge shape, such as stress release projection or interference of contact edge with stress concentration fillet. And experimental results of fretting fatigue strength improvement with stress release projection can be explained analytically. The two-stage S-N curve can be shown in joint structures, in which contact edge is set near the stress concentration fillet. These feature also can be explained analytically in this paper.
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Kyohei KUWADA, Yasuhiro TANAKA, Masanobu KUBOTA, Yoshiyuki KONDO
Article type: Article
Session ID: 2321
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The effect of hydrogen gas environment on fretting fatigue strengths of pre-strained SUS316L and SUS304 was investigated. The tests were continued up to 3×10^7 cycles. Hydrogen gas pressure was 0.12MPa in absolute pressure. Fretting fatigue strengths of SUS316L and SUS304 in hydrogen gas were decreased than those in air. The reduction of fretting fatigue strength at 3×10^7 cycles in hydrogen gas environment compared with that in air was 7% for the pre-strained SUS316L and 24% for the pre-strained SUS304. Tangential force coefficient was higher in hydrogen gas than in air. The propagation of fretting fatigue crack started at 97% of the fretting fatigue life in hydrogen gas. Non-propagating cracks were observed in H_2 gas but not observed in air in the specimens of SUS304 endured 3×10^7 cycles of fatigue loading.
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Tadao KAGIWADA, Hiroyuki HARADA
Article type: Article
Session ID: 2322
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Loosening of the wheel nuts may be the cause of accidents where the wheel falls off while the automobile is running. When the transverse force of wheel bolts exceeds a certain proportion of the bolt shaft force, the wheel nut begins to loosen. The authors examined, in the previous report, the proportion of the transverse force to the bolt shaft force in the case that the transverse force acts rotating and continuous. In this report, the proportion of the forces where the wheel nut begins to loosen is further examined. In the results it is clear that, the wheel nut begins to loosen by smaller proportion of the transverse force due to rotating-continuous transverse force than the proportion due to straight-repetitive transverse force.
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Shinji HASHIMURA, Chihiro INOUE, Yoshihiko MORI, Kyouichi KOMATSU
Article type: Article
Session ID: 2323
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Clamping force of bolted joints greatly influences strength of bolted joints. However clamping force of torque control method as tightening method well known varies widely. In this study, a new tightening method of bolted joints to accurately control the clamping force has been proposed. The proposed method tightens bolted joints by applying the same tensile force as the target clamping force to the thread part of bolt protruding through the nut. Experiments to verity the usefulness of the proposed method have been performed. The result show that the proposed method can accurately tighten bolted joints with an error of approximately ±10% against the target.
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Hiroyuki KINOSHITA, Koichi KAIZU, Hitoo TOKUNAGA, Kiyohiko IKEDA
Article type: Article
Session ID: 2324
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In riveting, it is very important to make the plate's deformation small as well as to obtain the high joint strength. Therefore, we proposed the riveting process using the washer in the same way as the bolt joint in order to accomplish both purposes. In this paper, the deformation and strength of the joints riveted using the washer were investigated. The obtained results show that the joint strength is improved while the deformation of the joint decreases. The usefulness of the proposed method was confirmed from those results.
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