-
Junichi OKADA, Koichiro KAWASHIMA, Naoya NISHIMURA, Hiroshi MAEDA
Article type: Article
Pages
195-196
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The conventional ultrasonic techniques are ineffective for detection of minute cracks of which surfaces are partially in contact. The detection of the ensemble of such cracks is demonstrated for the steel plates which have minute cracks nucreated by spall. Large amplitude, say 10nm, burst waves of 5MHz were transmitted into the plate and the waves propagated through the plate were received a 10MHz broadband transducer. The fundamental and 2^<nd> harmonic amplitudes were calculated by FFT. For the plates containing minute cracks which can't be imaged by a C-scan acoustic microscope, the amplitude ratio of the 2^<nd> harmonic component to the fundamental one is nearly proportional to the input voltage, which is proportional to the amplitude of the incident wave. The proportional factor increases with an increases in impact stress. Namely severity of the spall damage. To the contrary, the ratio is kept nearly constant for defect-free plates.
View full abstract
-
Koichiro KAWASHIMA, Naoya NISHUIMURA, Masayuki KONDO, Tomokatu KOSUGA, ...
Article type: Article
Pages
197-198
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Plate impact tests were carried out on the new composites, which are carbon composite material impregnated with Si and carbon fiber carbon composites. The composite specimens have different orientation, 0°, 45°, 90°, to the impact plane. The spall damage within the target plate was nondestructively detected from the change in the received waves with a digital ultrasonic measurement system. The spall strength of the composites is higher for the large fiber orientation angle.
View full abstract
-
Masamichi KAWAI, Atsushi HACHINOHE, Hiroshi TAKAKURA, Kenichi KATOU
Article type: Article
Pages
199-200
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Anisotropic fatigue strength of the cross-ply fiber-metal laminate GLARE 3 under constant-amplitude loading conditions has been studied. Tension-tension fatigue tests were performed at room temperature on five kinds of plain coupon speciments [0/90]_θ with different off-axis fatigue strength rapidly decreased for every off-axis angle in the intermediate range of the fatigue lifetime, and it was followed by a fatigue limit. A more excellent fatigue performance of GLARE 3 in comparison with the high strength aluminum alloy was observed only in the glass fiber directions (0°and 90°) for the low fatigue lifetime range. The off-axis fatigue data plotted using the strength ratio were approximately represented by a single master S-N curve.
View full abstract
-
Tadao HARAGUCHI, Hideto SUZUKI, Masashi NAKAMURA, Hiromichi KATO, Tets ...
Article type: Article
Pages
201-202
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this study, fatigue reliability of halogen free substrate noticed as an environmental harmony type printed circuit board backing was evaluated. And, the examination was demonstratively carried out on the difference of the failure mechanism in fatigue breakdown and static destruction from the mesoscopic viewpoint. (1) There was a difference in both fatigue life, though mechanical property of the halogen free material was almost equal to it of the halogen material. That is to say, the fatigue life of the halogen free material was longer than the halogen material. (2) In the halogen free material, the crack was comparatively generated in initial stage in the fatigue life. In the meantime, in the halogen material, it immediately came to the rupture, when the crack was generated, and it was frailly destroyed. (3) From the fractographic study, it was indicated that the difference in fatigue life of the halogen free material and fatigue life of the halogen material was controlled by the difference of size (Unit Fracture Area) of the characteristic destruction pattern.
View full abstract
-
Tomonari Furukawa, Tomohiro Sugata, Shinobu Yoshimura, Genki Yagawa
Article type: Article
Pages
203-204
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Hideo FUJIMOTO, Akihito SANO, Takashi KOZAKI
Article type: Article
Pages
205-206
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Katsumi TANAKA, Yoshihiko NOMURA, Hirokazu MATSUI, Norihiko KATO
Article type: Article
Pages
207-208
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this study, fatigue reliability of halogen free substrate noticed as an environmental harmony type printed circuit board backing was evaluated. And, the examination was demonstratively carried out on the difference of the failure mechanism in fatigue breakdown and static destruction from the mesoscopic viewpoint. (1) There was a difference in both fatigue life, though mechanical property of the halogen free material was almost equal to it of the halogen material. That is to say, the fatigue life of the halogen free material was longer than the halogen material. (2) In the halogen free material, the crack was comparatively generated in initial stage in the fatigue life. In the meantime, in the halogen material, it immediately came to the rupture, when the crack was generated, and it was frailly destroyed. (3) From the fractographic study, it was indicated that the difference in fatigue life of the halogen free material and fatigue life of the halogen material was controlled by the difference of size (Unit Fracture Area) of the characteristic destruction pattern.
View full abstract
-
Keisuke OZAKI, Yosiaki KOMURA, Tetuya MORISAKI, Yasuhiro YAMADA
Article type: Article
Pages
209-210
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The purpose of this study is to analyze the possibility of autonomous movements by recognizing a self-position by camera and tetrahedron landmarks. In this paper the landmarks are composed of a tetrahedron of red or green colored balls 75 mm in the four apexes. The regular tetrahedron has a side length of 500 mm. In order to know the three-dimensional position the most suitable triangle for measuring is chosen from four equilateral triangles which compose the landmark. We propose a method for choosing the most suitable triangle for measuring. The validity of the proposed method is examined by numerical simulations.
View full abstract
-
Masatake SHIRAISHI, Shingo SUGANO, Shinnichi AOSHIMA
Article type: Article
Pages
211-212
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
To compensate for the effects of coupling torque and load variations experienced in SCARA-type robots, we propose a new method of sensor-based decoupling control. In this method the plant is first nominalized with the use of a disturbance observer and then nonlinear feedback control is accomplished by this nominalized system based on information from acceleration sensors installed at the end of the robot hand. As a result of high speed reciprocal motion with a 10 kg payload mounted on the hand, we were able to achieve satisfactory decoupling using this method. Improvements were also made in steady-state characteristics.
View full abstract
-
Motohisa SHIMADA, Yasushi TOAKE, Masahiro OHKA
Article type: Article
Pages
213-214
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to cause a tactile sensor to be thin shape, a new optical tactile sensor is developed by applying computed tomography (CT). The present tactile sensor is comprised of infrared emitting diode array, the receiving phototransistor array and transparent silicon rubber plate. Infrared rays emitted from the diode array are directed into an end of the plate and their intensity distribution is measured by the phototransistor array mounted on the other end. If CT algorithm is directly applied to the tactile sensor, there are two defects such as shape of sensing area limited to a circle and long calculation time. Thus, a new CT algorithm oriented to tactile sensing is proposed to overcome these defects. In the present algorithm, a square sensing area is divided to an n-by-n array and algebraic equations are derived from relationship input and output light intensities on assumed light projections. To validate the present algorithm, a sires of simulation was performed and it was found that tactile image was completely reconstructed in the case under 6-by-6 array.
View full abstract
-
Jun OHMURA, Tokuhiro SUGIURA, Yoshihiko NOMURA, Yasunaga MITSUYA
Article type: Article
Pages
215-216
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes a image region segmentation algorithm : each pixel is segmented, based on the information of the regions located on both above and below the pixel. As an example for the feature value of each target pixel, we utilize the average and the standard deviation of the intensity value of the neighboring pixels, which belong to upper and lower region of the target pixel. Then each target pixel will be projected into and analyzed in a feature space called multi dimensional co-occurrence matrix : the feature space is, conceptually, composed of two pieces of subspace, i.e., one spanned by upper region features and the other by lower ones. In the case of two feature values, the subspace is represented as a two dimensional (2-D) plane, and, the target pixel is projected as a kind of connecting segment between the two subspace planes in the feature space. After having excluded boundary pixels, while fitting 2-D Gaussian distributions, we classify the target pixels into homogeneous regions based on a criterion : segments corresponding to inner pixels have gradients of nearly zero, and those to boundary pixels have much larger gradients.
View full abstract
-
Tetsuya KOIDE, Takashi WATANABE
Article type: Article
Pages
217-218
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
There are many opportunities for our communication and consideration to draw diagrams and pictures. We have been studying a human-machine interface which accepts diagrams and understands their meanings in application domains, and proposed a useful and flexible system. The system has a rule-based inference mechanism and recognizes the domain where the diagram should be understood. In this paper, we construct an interface system to communicate in natural language (Japanese). In addition to the inference mechanism, the new system consists of three subsystems : a decomposition mechanism of input sentences, a conversion mechanism of sentences into command lines and a drawing system. These subsystems presents an integrated interface which makes communication with diagrams more natural and practical.
View full abstract
-
Mamoru Minami, Toshiyuki Asakura, Takeshi Ikeda, Tomohiro Koturu
Article type: Article
Pages
219-220
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Induced force and torque by the travelling motion effect to the carrying objects. If they are bigger than the static friction force and torque, the carrying objects may slip on the mobile manipulator. It is dangerous, because this motion may cause a collapse of loads. And it interferes with accurate operations such as loading, carrying and unloading, which are fundamental function of the mobile manipulator. A purpose of previous research was to guide a mobile manipulator without a movement of carrying objects. Therefore, it is not considered the dynamical effects of carrying object. A purpose of this research is to make a model considering a movement of carrying objects on the mobile manipulator. First, a dynamical nonholonomic mobile robot is formulated. Second, a justification of the model is verified by simulation. Third, the same, a dynamical nonholonomic mobile manipulator with one link is formulated. Finally, a justification of the model is verified by simulations.
View full abstract
-
Kousuke Hayashi, Takeshi Nakada, Toshiharu Kagawa, Keizo Otani
Article type: Article
Pages
221-222
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A pneumatic nozzle flapper is an important displacement pressure converting element in pneumatic control systems. Recently, the drive current applied to a nozzle flapper tends to be smaller for saving the electric power and the drive force of the flapper is considered to be on the order of the flow force. As a result, the flow force influences the flapper displacement. So it is necessary to predict accurately the characteristics of the nozzle flapper. In this paper, the pneumatic nozzle flapper model including flow force of air jet through nozzle is proposed and the characteristics of the flow force are experimentally analyzed by the frequency response tests. There are 2 kind of the flow forces, that is, the flow force of static pressure and dynamic pressure, however the flow force of dynamic pressure is a negligible quantity, when the pneumatic nozzle flapper is designed.
View full abstract
-
Kazuhiro YOSHIDA, Tamaki TAKAMATSU, Shinichi YOKOTA
Article type: Article
Pages
223-224
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
By using MR fluid whose apparent viscosity is controlled by the applied magnetic field intensity, a simple microvalve called micro MR valve has been proposed by the authors for micromachines using high density fluid power. To increase the controllable magnetic field intensity, the micro MR valve utilizes a thermally-controlled magnetic circuit composed of a permanent magnet, a thermosensitive ferrite, and Peltier elements. In this paper, a micro MR valve with 8.8×7×5(mm)^3 in size is fabricated and the basic characteristics are experimentally investigated. The static and dynamic characteristics of the thermally-controlled magnetic circuit are clarified and the valve control performance is verified.
View full abstract
-
Kazuhiro YOSHIDA, Masaaki KIKUCHI, Jung Ho PARK, Shinichi YOKOTA
Article type: Article
Pages
225-226
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
As an advanced control component for realization of high power micromachines using fluid power in millimeter size, the authors have proposed a simple micro ER valve using homogeneous ER fluids and fabricated several micro ER valves by conventional machining. Besides, to control micro grippers mounted on micromachines, further miniaturized 2-port micro ER valves have been fabricated by micromachining using anisotropic etching, sputter and anodic bonding. In this study, a 3-port micro ER valve composed of two 2-port micro ER valves is fabricated. Each 2-port micro ER valve has electrode dimensions of 1.2mm in width, 5mm in length and 0.08mm in gap length. Firstly, the static and dynamic characteristics are experimentally investigated with the blocked control port. From the results, it is ascertained that the controllable pressure change rate is about 60% of supply pressure and the rise time is about 0.2s. Next, an application to position control of a bellows microactuator is performed. With supply pressure of 0.17MPa and electric field strength change of 4.0kV/mm, the output displacement of 0.09mm and the generation force of 0.47N are realized.
View full abstract
-
Yutaka KONDOH, Kokichi ISHIHARA, Shinichi YOKOTA, Yasuhumi OTSUBO, Kaz ...
Article type: Article
Pages
227-228
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Recently Otsubo and Edamura reported that dielectric fluids showed striking viscosity increase on the application of electric field when the electrode surface was planted with hair-like short fibers. By using the phenomenon, ER effect applications are expected without ER fluids. This study aims to develop a fluid control valve with the ER effect caused by fiber planted electrodes. In this paper, firstly, the fiber planted ER valve, which have fiber planted high voltage electrode and normal surface ground electrode, is proposed. The valve can control fluid power with applied voltage. Secondly, as an application of a fiber planted ER valve, a 4-port fiber planted ER valve is proposed and fabricated. And then, it is demonstrated that a 4-port fiber planted ER valve can control a piston-cylinder.
View full abstract
-
Naoki YAMANE, Masahiro OHKA, Yasunaga MITSUYA
Article type: Article
Pages
229-230
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A robotic manipulator equipped an optical three-axis tactile sensor can detect the distribution of not only vertical but also horizontal force. This sensor is composed of a silicone-rubber sheet, an acrylic plate, a CCD camera and a light source. A silicone-rubber sheet has an array of 8×9 sensor cells consisting of columnar feeler and 2-by-2 conical feelers. Since the reflectance of silicone-rubber is naturally low, the contact area between conical feelers and an acrylic plate cannot be accurately identified. Thus we developed a new silicone-rubber sheet with high reflectance by adding aluminum powder into pre-hardened silicone-rubber. In the experiments, we measured the sensitivity of the present sensor equipped aluminum powder doped silicone-rubber sheet. As a result, the sensitivity of the present tactile sensor was enhanced because clearness of contact contour caused identification of contact area to be more precise.
View full abstract
-
Hitoshi Takeuchi, Takeshi Nakada, Kazuya Edamura, Takaaki Kurihara
Article type: Article
Pages
231-232
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper deals with the constructions and their characteristics of the linear actuators, which a new functional fluid so-called ECF is applied to. ECF is an electric fluid having dibutyl decanedioate as its main ingredient, and a strong flow is generated from the anode to cathode when an electric field is applied to ECF. Tow types of the linear actuators are developed and their characteristics such as driving speed to applied voltage and driving force to driving speed are evaluated.
View full abstract
-
Shinichi YOKOTA, Daisuke SASE, Yutaka KONDOH, Yasufumi OTSUBO, Kazuya ...
Article type: Article
Pages
233-234
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Some kinds of dielectric fluids such as dibutyl decanedioate generate jet flow between electrodes. One of the authors names the fluids ECF (Electro-conjugate Fluids), which are considered as smart fluids. In this study, disk plate type motors by making use of ECF are proposed, whose feature is low height. The proposed disk plate type ECF motors have two type. One is DPSE (disk plate stator electrode) type, whose electrodes are located on the inside wall of the stator filled with ECF. The other is DP-RE (disk plate rotor electrode) type, whose electrodes are located on the rotor surface. In this paper, fabrication of DP-RE type ECF motors having 0.7mm and 1.6mm in inner height is described. Basic characteristics such as rotational velocity, load characteristics, output power, efficiency are experimentally examined. Finally, Comparison of basic characterisitcs between DP-RE type ECF motors having 0.7mm, 1.6mm and 2.5mm in inner height is described.
View full abstract
-
Masahiro OHKA, Yukio Muramatsu
Article type: Article
Pages
235-236
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the virtual reality for tactile sensation. Since human beings grasp an object according to the surface condition and recognize material of the object, it is important for handling and inspecting objects that human beings recognize object surface. In virtual reality, the tactile sensation is important to enhance the reality of objects presented. Although, several tactile presentation devises have been reported so far, there are a few matrix-typed tactile presentation devises. Since human tactile receptors are distributed on entire fingertip surface, the matrix-typed tactile presentation device is essential to realize the virtual reality for tactile sensation. In this paper, multi-layer piezoelectric ceramic actuators were used for a pressure generator because they can control precise displacement. The single pressure stimulator is composed of four PZT ceramic actuators (displacement of a PZT ceramic actuator is 15 microns per 100 V) and a lever capable of enlarging displacement caused by the PZT ceramic actuators. A tactile presentation device was comprised of 2-by-2 pressure stimulators. To avoid vibration the tactile presentation device was mounted on an X-Y table using linear air-bearings. During experiments, six human subjects touched basic virtual figures such as a circle, a triangle and a square to obtain reasonable distance between two pressure points. From edge trace tests, we estmate the reasonable distance would exist between 1 and 2 mm.
View full abstract
-
Yukihiro MOURI, Masahiro Ohka, Tokuhiro SUGIURA, Yasunaga MITSUYA
Article type: Article
Pages
237-238
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the development of a tactile presentation system mounted on a mouse. Since human tactile receptors are distributed on entire fingertip surface, the matrix typed tactile presentation device is essential for the virtual reality for tactile sensation. In this paper, a tactile presentation system was designed using piezoelectric ceramic actuators (PZT ceramic actuator) for pressure stimulator because they can control precise displacement. The key part of the system, a Braille cell presenting Braille dots, was an array of eight PZT ceramic actuators (displacement of a PZT ceramic actuator is 1mm/200 V). Three braille cells were mounted on a mouse to generate distributed pressure with 4-by-6 stimulating points. In order to examine the basic size of texture that the present device displays, recognition experiments were performed using virtual figures of 10.8mm to 104.9mm in size. It was found that if size of the virtual figures exceeded 26mm then human subjects could recognize the figures with high percentage of correct answers being more than 80 percent of correct.
View full abstract
-
Yusuke Sezaki, Shohei Niwa, Takanobu Masuda, Kaname Nezu
Article type: Article
Pages
239-240
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This reseach is intended to control the mobile robot by the visual sensor. We consider an estimation algorithm to obtain the position and moution of the camera and the moving object using Kalman filter to process the image data. Applying the estimation algorithm, a design of control system for the mobile robot is presented. Numerical and experimented researctes show the validity of the visual sensor.
View full abstract
-
Yoshinobu SAWANO, Yoshiaki SHIRAI, Jun MIURA
Article type: Article
Pages
241-242
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes a control method of chasing parson by a vision guided mobile robot in wholly unknown indoor environment. The robot obtains the environment information by repeating observing Stereo vision. By making a map using the information, it decides the optimal path to chase the parson avoiding obstacles. Since the observation by stereo may have an ambiguity, for example, recognizing nonexistent obstacles or not recognizing existent obstacle. Modeling this ambiguity, we compute the reliability of map by integrating multiple observation results.
View full abstract
-
Takashi IKEUCHI, Terumoto KOMORI, Yoshihiko NOMURA, Hirokazu MATSUI, N ...
Article type: Article
Pages
243-244
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Bayesian estimation is often applied in pattern recognition problems. We formulate estimation errors of a posteriori Bayesian probabilities to be propagated from observation. Next, we apply the scheme of the formulation to a practical image recognition problem : based on a posteriori probabilities, sectionalized regions in outdoor-scene images are classified into five categories of landform elements, i.e., asphalt, concrete, sand/soil, gravel, and grass. The errors originate from RGB pixel values within a region, and propagate to the a posteriori probabilities via intermediary HIS color measures. We concretely clarify a mechanism of the propagation for all steps, and show an effectiveness of the scheme by adducing changeovers between a posteriori probabilities with two kinds of landform elements.
View full abstract
-
Terumoto KOMORI, Norihiko KATO, Yoshihiko NOMURA, Hirokazu MATSUI
Article type: Article
Pages
245-246
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
There sometimes occur problems in observational data : (1) "inaccuracy", especially, due to outliner data, (2) "incompleteness" that data don't satisfy sufficient conditions. In addition to these, there occurs another problem, when integrating multiple pieces of information, i.e., "contradiction" between the information. These problems with observations, furthermore, result in characteristic problems with recognition : (1) "uncertainty", (2) "ignorance", and (3) "contradiction", respectively. These problems degrade credibility of recognition system. This paper proposes following methods for these problems : (1) a calculation method of a feature value considering the outliner observations (2) a quantification method of the "ignorance" by applying the Dempster-Shafer theory (3) another quantification method of the "contradiction" with upper and lower bounds.
View full abstract
-
Toshihiro SERA, Sunao SATOH, Hirohisa HORINOUCHI, Kohichi KOBAYASHI, K ...
Article type: Article
Pages
247-248
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Yuji Matsuzaki, Tadashige Ikeda, Shinji Deguchi, Nobuhiro Yamauchi
Article type: Article
Pages
249-250
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this paper the effect of the configuration of the vocal fold on voice generation is investigated using a two-dimensional flexible channel model of the vocal fold coupled with a one-dimensional unsteady flow model. Especially, we examine the relationship between vocal fold thickness and minimum lung pressure for voice generation. The numerical result shows that there exists an optimal thickness of the vocal fold for ease of phonation since the relationship has a U-shape.
View full abstract
-
Shigehiko KANEKO, Hiroki FUKUDOME, Yasuhiro YOSHIZAWA
Article type: Article
Pages
251-252
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Kenichi HANAZONO, Kenkichi OHBA, Kiyoshi BANDO, Atsushi SAKURAI, Taday ...
Article type: Article
Pages
253-254
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Experimental and theoretical study on a steady flow in largely deformed collapsible tube was performed to evaluate the feasibility of applying a static tube law to the tube under a steady flow condition. We measured a static tube law. Cross sectional shape of the tube and velocity profile across the tube at several different positions along the tube were also measured using a laser light sheet and LDV, respectively. Pressure distributions along the tube were calculated by taking into account change in a cross sectional shape of the tube and a flow separation due to a sudden expansion of the tube. It was compared with the one from a static tube law. The results showed a small difference between a transmural pressure from the tube law and the calculated one at downstream of the mostly collapsed portion of the tube.
View full abstract
-
Daisuke YAMASHITA, Youji NIMI, Kiyoshi BANDO, Kenkichi OHBA
Article type: Article
Pages
255-256
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to study characteristics of flow through a collapsible tube, and its self-excited oscillation, etc., it is important to elucidate a dynamic deformation characteristics of the collapsible tube as a model blood vessel when it is subjected to transmural pressure. Hence, we have studied a dynamic tube law by numerical simulation. In this paper, we have made a calculation about the deformation of a tube section by using a dynamic explicit finite element method. To evaluate the validity of our calculation, we have calculated the static tube deformation and have compared our data with conventional valid one. Also, we have investigated the tube deformation when the tube is subjected to impulsive pressure. As a result, it is shown that their agreements with the conventional results are good.
View full abstract
-
Tadashi NAKAGAWA, Atsushi SHIRAI, Toshiyuki HAYASE, Satoru HAYASHI, Ry ...
Article type: Article
Pages
257-258
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This report deals with a numerical analysis on the stability of a flow in a right angle side branch. Spatial growth of velocity perturbation at the upstream boundary of the side branch is examined for various frequencies. The computational result revealed that frequency range of the maximum amplification coincides with that of the fluctuation observed in experiment. Distribution of the wall shear stress fluctuation due to instability shows the local extremum in both the proximal and the distal wall.
View full abstract
-
Yusuke KIMURA, Daisuke UJIHARA, Takami YAMAGUCHI
Article type: Article
Pages
259-260
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
We studied the relationship between the blood flow and the atherosclerosis using Computational Fluid Dynamics (CFD). Atherosclerosis tends to grow at the bifurcation of abdominal aorta, particularly at the lateral side walls of the common iliac arteries. In general, the bifurcation of blood vessels has a sharp edge, and therefore the minute deformation and movement of the bifurcation are thought to have a large effect on the blood flow. In order to study the blood flow at the bifurcation using realistic CFD model, we developed a modeling system using micrometer thick slicing to reconstruct the 3-dimensional blood vessel configuration for CFD analysis.
View full abstract
-
Ryo TORII, Marie OSHIMA, Toshio KOBAYASHI, [in Japanese], Kiyoshi TAKA ...
Article type: Article
Pages
261-262
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Hidenobu NAGATA, Shigeo WADA, Takeshi KARINO
Article type: Article
Pages
263-264
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
It has been shown that intimal hyperplasia develops preferentially at the distal anastomosis of a bypass-grafted artery where flow is disturbed and complex secondary and recirculation flows form. Hence to elucidate the mechanism of localization of intimal hyperplasia, it is necessary to investigate the relationship between the preferred sites of intimal hyperplasia and the flow prevailing there. For that purpose, computational fluid dynamics (CFD) provides a powerful tool. In our present work, we developed first a new modeling system to construct anatomically realistic 3-dimensional CFD models from resinous casts of real arteries, and then calculated detailed flow patterns at the distal anastomosis of a bypass-grafted artery.
View full abstract
-
Keisuke FUKUYAMA, Daisuke MORI, Tomoaki HAYASAKA, Hao LIU, Takami YAMA ...
Article type: Article
Pages
265-266
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The three dimensional (3D) configuration of the arteries is very complex and this complex 3D geometry is considered to determine the distribution of mechanical forces exerted on the arterial wall by the blood flow. The 3D configuration of the aortic arch was modeled in the present study to analyze a single helical blood flow shown by clinical magnetic resonance imaging (MRI) studies. The single helical flow was thought to occur by a combination of the 3D distortion of the arch and the complex geometry of the major branches, and was thought to be responsible for the development of aortic aneurysms.
View full abstract
-
Daisuke MORI, Hao LIU, Takami YAMAGUCHI
Article type: Article
Pages
267-268
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
It was recently pointed out that the centerline of the aortic arch does not lie in a plane, and has a three dimensional (3D) distortion. This distortion is thought to be a risk factor of the development of aneurysms. In the present study. We constructed a realistic CFD model of the aorta based on MRI measurements. Simulated the flow inside the aorta. Investigated the effect of 3D distortion of the arch on the blood flow, and discussed its pathophysiological significance. We showed that the 3Ddistortion of the aorta caused a complex flow pattern, which resulted in the localized WSS distribution. We suggest that the complex WSS distribution may be related to the development of aneurysms and atherosclerosis at the arch.
View full abstract
-
Hao LIU, Takami YAMAGUCHI
Article type: Article
Pages
269-270
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The cardiovascular system is an internal flow network with multiple branches in which three-dimensional and pulsatile blood flow circulates. We propose a new paradigm of simulation-based biomedical engineering, which is designed to provide a basis for the patient-specific modeling in predictive medicine. Such paradigm requires a global computational modeling of cardiovascular blood flow. We here highlight some important issues to be involved in such modeling and carry out an extensive study on the treatment of boundary conditions.
View full abstract
-
Masanori Nakamura, Shigeo Wada, Taisei Mikami, Akira Kitabatake, Takes ...
Article type: Article
Pages
271-272
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
It has been shown that a spatiotemporal map of the intraventricular velocity distribution obtained with the color M-mode Doppler echocardiography reflects relaxation properties of the myocardium of the left ventricle (LV). However, the precise mechanisms are not fully understood. Hence we have carried out a CFD study of the intraventricular flow during an early diastolic phase using a two-dimensional axisymmetic model of the LV. The result showed that the color M-mode images obtained with CFD qualitatively agreed with those obtained in clinical measurements. It was concluded that the intensity and the migration velocity of the vortex that formed in the left ventricle are reflected on the color M-mode images obtained with an ultrasound Doppler echocardiography.
View full abstract
-
Makoto KAWAKAMI, Shigenori SHIROUZU, Hisanobu SUGANO
Article type: Article
Pages
273-274
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
To confirm the formation of dicrotic pulse waveform of blood flow due to the elastic effect of artery, a fully coupled fluid-structure interaction finite element analysis were performed. Artery, blood, and blood ejection effect were modeled with a straight elastic tube, Navier-Stokes fluid model, and intermitted volumetric pulse wave. Significant dicrotic waves were observed for the elastic modulus 0.3 MPa and the level of dicrotic wave decreased for the elastic modulus 3.0 MPa.
View full abstract
-
Tomoki KITAWAKI, Ryutaro HIMENO
Article type: Article
Pages
275-276
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Tsuyoshi OHASHI, Hao LIU, Takami YAMAGUCHI
Article type: Article
Pages
277-278
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In the coronary arteries, it is recognized that a sudden disruption of atherosclerotic plaque and a rapid thrombus formation around the plaque stops the blood flow, and causes a sudden death. This is called Acuate coronary Syndrome (ACS) which is recently drawing clinical attention. A computational analysis of the fluid-wall interactions using models of the arterial stenosis was carried out in the present study. As a computational result, we found a specific distribution of the principal stretch in the shoulder of the plaque which is a junction of the plaque and the normal blood vessel wall. This is the focus frequently reported to disrupt from the clinical observations. We suggest the stretch concentration in the shoulder region might have some relationship with the plaque disruption.
View full abstract
-
Masaaki TAMAGAWA, Ichiroh YAMANOI, Bernd GENENGER, Marcus SCHAEFER
Article type: Article
Pages
279-280
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the analysis of coupling oscillation problems between the cell deformations and flow induced by propagating underwater shock waves. Actually the cells including cavitation bubbles are destroyed by using under water shock waves when the new bio-process method is used for environmental protection. For this analysis, the cells are modeled as liquid droplet including gas bubbles. By computation using ALE(Arbitrary Lagragian-Eulerian) Method, the coupling oscillation is analyzed. The results shows that the effects of the acoustic impedance of the fluid media in water is large for the deformation process.
View full abstract
-
Hisako MIYAZAKI, Hao LIU, Takami YAMAGUCHI
Article type: Article
Pages
281-282
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Platelets play an important role in blood coagulation, particularly in the formation of primary thrombi. It is thought that the aggregation of platelets, which initiates primary thrombi formation, is mediated by a macromolecule called von Willebrand Factor (vWF). We analyzed the mechanical interactions between platelets, the vessel wall, and vWF using a discrete element method (DEM) that can treat solid elements in a flow without assuming continuity, in order to establish guidelines for the design of artificial platelets. The DEM was thought to have the potential to simulate the discontinuous movement of blood constituents, such as platelets. This simulation displayed a very interesting phenomenon of the destruction of an aggregated thrombus under the influence of vWF.
View full abstract
-
Hirohisa MORIKAWA, Taro MINAMOTO, Shunichi KOBAYASHI, Masayuki SAKURAI ...
Article type: Article
Pages
283-284
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The objective of our study is experimentally to investigate both the flow characteristics over the mucus of fish and the mechanism of drag reduction. The water flow and the mucus layer over a porous plate exuding mucus (Polyethylene glycol) modeled on the coating of mucus over the bodies of fish were measured by a LDV in the range of low Reynolds numbers. The large slip on velocity was found in the vicinity of the interface between the mucus and the water.
View full abstract
-
Mohammad Hamidul, Masashi Watanabe, Hirohisa Morikawa, Toshihiro Hirai
Article type: Article
Pages
285-286
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Slip of Newtonian fluid in (0.80 and 0.40 mm diameter) intact and modified PVA hydrogel tubes was studies. In this experiment, the slip is inferred by observing the motion of micron-sized spherical monodispersed polystyrene particles suspended in the flowing water by using an optical microscope from very low to medium flow rate. The particle velocity was estimated by both particle tracking (PT) and particle image deformation (PID) method and the slip velocity was measured by extrapolating the experimental data of the velocity profiles on the gel surfaces. Microscopic measurements reveals that the slip velocities on the hydrogel surfaces depend on the chemical nature of the hydrogel surfaces and it is proportional to Reynolds number.
View full abstract
-
Shigeo WADA, Ryo KOBAYASHI, Yoshiaki TAKAHASHI, Takeshi KARINO
Article type: Article
Pages
287-288
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
It has been shown that a red cell (erythrocyte) can transform itself into a variety of shapes under various conditions. However, there is no theoretical model which can explain it well. Hence we developed a mathematical model of a red cell which can deform into any shape while keeping the elastic energy of the membrane minimum, and simulated the shape change which occurred when the volume of a red cell in a spherical shape was reduced gradually. It was found that the process of the shape change of the cell from a sphere to a biconcave disc which is similar to that of a normal red cell can be simulated fairly well by this model.
View full abstract
-
Itsuki YOZA, Kenkichi OHBA, Kiyoshi BANDO, Atsushi SAKURAI, Tadashi UR ...
Article type: Article
Pages
289-290
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to make a precise experiment in vitro for simulating blood flow in vivo, we have been using high concentration suspension of alginic acid gel particles in various dispersion media as a model blood. In our early study it was clarified that this model blood obeyed Casson's diagram like actual blood, and it formed aggregation at low shear rate like actual red blood cell when it was dispersed in an aqueous solution of CaCl_2. In this study we investigated an elasticity of the model blood cell by a manipulator system. As a result, the followings were clarified; the model blood cell had residual deformation when the time duration that the particle was deformed was longer than about 1 min. We measured the force that deformed the particle by pushing the particle to the tip of the beam. As a result, we got a relationship between stress and deformation of the model blood cell. Moreover we found that force relaxation occurred when the stress was inflicted on the particle in long period.
View full abstract
-
Takuji ISHIKAWA, Nobuyoshi KAWABATA, Motoyoshi TACHIBANA
Article type: Article
Pages
291-292
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The blood flow in large arteries is commonly analyzed by means of the constitutive equations. However, it is not appropriate to use constitutive equations for small arteries because of the heterogeneity of the blood. In this paper, a new method to model an erythrocyte by using beads and springs is proposed as an alternative to analyze the blood flow. The behavior of a single erythrocyte is computed under a constant shear field. The results show that the bead-spring model appropriately can simulate the tank tread motion of an erythrocyte under a high shear field and stress thinning. It is therefore considered that the bead-spring erythrocyte model is able to consistently express blood characteristics
View full abstract
-
Osamu MARUYAMA, Takashi YAMANE, Masahiro NISHIDA, Aouidef Ahmed, Tatsu ...
Article type: Article
Pages
293-294
Published: July 31, 2000
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
We are developing microcapsule suspension, which is expected to be used for absolute hemolysis evaluation instead of animal blood. In this report, we describe fractural characteristics of microcapsule suspension under fluid dynamical shear stress, which is generated by rotational shear stressor developed in our laboratory. We tested two types of microcapsule suspension. One has 100 micrometer diameter and polyurethane membrane, and the other has 10 micrometer diameter and melamine membrane. Fractural property of the former suspension was similar to that of bovine blood, whereas the later suspenstion showed different result. This tendency seems to be caused by the laminar/turbulent combined flow condition in the shear stressor.
View full abstract
