vol.15 (2002)

Bulletin of Computational Science Research Center
Vol.15, 2002 ISSN 0913-8420 Published March 23, 2002

Numerical simulation and visualization of space debris impact
-Analysis in the low speed impact and verification by experiment-

Kenji Sugihara, Yuji Yasuda, Kazuyoshi Arai, Yutaka Tanaka
PDF   Abstract
In recent years, as space development proceeds, the space debris such as a flake of the artificial satellite that has been used has increased markedly in the cosmic space. The speed of space debris is the ultra high-speed of about 8km/s, and the phenomenon that the space debris collides to the space structure causes a serious problem. The purpose of this research is to clear the damage mechanism of the composition material when the space debris collides to the space structure As the first step, the impact phenomenon in low speed region was simulated numerically. Furthermore, the visualization experiment of the impact phenomenon and the damage experiment were investigated to examine the validity of the results of numerical analysis.
Immersive Distance Learning for Playing on Musical Instruments
Shingo Ara, Yutaka Tanaka
PDF   Abstract
Recently, Computer Assisted Instruction (CAI) class has been experimentally carried out in wide variety of education and training. It is effective for students in class to learn by using motion pictures and real sound. Conventional CAI systems have consisted of text and still images based on contents without a sense of reality. There are a few exceptions, but a special hardware and software for processing the contents are expensive. The purpose of this study is to develop a musical instruments learning system communicated by network between some users. Each user such as teachers and students are connected and collaborate with another users in the musical contents. In this system every user are virtually located in a virtual concert hall and share the same time and same music contents. Performance of the developed learning system is experimentally investigated for twenty subjects as the users in music class. After the users collaborate and practice a predetermined music for playing the virtual keyboard in the class, the audience appreciates and evaluates the playing of the keyboard in the virtual concert hall. Almost the entire subjects are pointed out that the learning system has good performance for playing on the music keyboard. There are some problem about the sound quality and operation of the virtual keyboard in the system. Commercial available MIDI instruments are effective to solve these problems.
Visualization and Haptization for Swirling Flow in a Pipe
Shintarou KASHIWABARA, Yutaka TANAKA, Ryushi SUZUKI
PDF   Abstract
It has been important problem to communicate comprehensibly to the science and technology data. With the advance on recent computer technology, it is possible that computer graphics displays spatial distribution data for physical phenomena in a real environment. On comprehension of the spatial distribution data, however, conventional visual displaying techniques have not provided realistic image and interactive sensation for presentation of the data. In this study, a prototype of haptic system for scientific visualization using virtual reality technology has been developed. A pattern of the swirling flow in a bubble elimination device is applied to investigate the visualization and haptization of the flow fields.
Proposal of New Concept for Event Sending in Tele-Operated Manipulation System
Hidetoshi Chikamori, Yutaka Tanaka
PDF   Abstract
In tele-operated manipulations, it is an important problem for operators to have overload of operations by communication with time delay. In this paper, we have proposed and developed a new concept of the tele-operated manipulation with a new concept of operations; an event sending type. The word “event” means the factor of a thing’s occurring. In our research, this word is dealt with start or restart signals of operation and the process. It is classified the events into a real time, a packet and parts data sending process, respectively. In the real time data sending process, the operation data are directly sent to the remote location. In the packet data process, the operation data for the start for end points are packed together and transmitted to the remote location. In the parts data process, a part of the operating data is directly sent and remaining data are reconstructed automatically at the remote location. It is experimentally verified to reduce the overload of works and improve the efficiency of operations by using the proposed event sending method.
Computation of Reverse Flow in a Channel with an Obstruction in Front
H.L.Gowda, S.Mizuki
PDF   Abstract
Reverse flow occurs in a channel when an obstruction is placed at the entry. The phenomenon involves separation, reattachment and shear layer interaction. The various facets of the phenomenon have earlier been investigated experimentally. Presently, an attempt has been made to compute this flow solving unsteady equations of motion. Preliminary results do predict the occurance of reverse flow.
Molecular Dynamics of Methanol
Yosuke Akino, Yosuke Kataoka
PDF   Abstract
In the polyatomic molecule, the changes of bond angle and bond length slightly occur in the intra-molecule. However, it is difficult to reproduce well the flexibility of intra-molecules by the molecular dynamics simulation. In this study, we carried out molecular dynamics simulation of liquid methanol, and examined the effect by intra-molecular flexibility in the simulation. We used application program “WinMASPHYC” for present simulation.
Reaction Analysis of Ester by Semi-empirical Molecular Orbital Method
Atsushi Kondo, Yosuke Kataoka
PDF   Abstract
We simulated the reaction of ester and searched for its process by program package of semi-empirical molecular orbital calculation, MOPAC. As a result, we confirmed that ester reacts with solvent, and then they form objective products; ester, carboxylic acid and others. And we found the ratio of ester to solvent is 1 to 2 in the case of using acid catalyst.
Image reconstruction for myocardial SPECT with an optimum projection data
Satoru Ohno, Koichi Ogawa
PDF   Abstract
This paper describes a new data acquisition scheme for myocardial single photon emission CT with a semiconductor detector. The proposed data acquisition scheme is to measure projection data with angles where the signal to noise ratio in projection data is relatively high. We carefully decided the minimum number of projections and selected optimum projection angles according to their power spectra. These selected eight projections were divided into four subsets and we reconstructed images with an ordered subset expectation maximization method. As a result, even with only eight projection data we could obtain images of almost the same quality as those with 60 projections
Accurate vascular reconstruction with MAP-EM method from few projections
Yuki Kajiura, Koichi Ogawa, Etsuo Kunieda
PDF   Abstract
We proposed a new image reconstruction method of intracerebral vessels from few two-dimensional projection data. This method uses an iterative image reconstruction method, Maximum A Posteriori-Expectation Maximization method. In order to increase the convergence speed, we modeled the reconstruction process with two stages and introduced a penalty function which enables us to keep the continuity of blood vessels. We evaluated the proposed method by means of a simulation phantom and an experiment phantom made with a curved wire. The number of projection views used was five (RAO 60, 30, LAO 60, 30 and 0 deg.). The quality of the image was evaluated by the profiles of reconstructed three-dimensional images. These profiles showed the improvement in voxel values at low voxel-value areas with the proposed method. The results showed that the proposed method was useful for the reconstruction of vessels with few projections.
Quantitative evaluation of distortions in myocardial SPECT image
Masaru Nagase, Koichi Ogawa
PDF   Abstract
In myocardial single photon emission CT (SPECT), reconstructed images are distorted by motion of the heart during data acquisition, and attenuation and Compton scattering of gamma rays. This paper analyzed degradation of myocardial SPECT images for above points with the dynamic MCAT (DMCAT) phantom. Computer simulations were done considering the influences of motion of the heart, attenuation of gamma rays and the Compton scattered rays originated in the liver.
Comparison of scatter correction methods in simultaneous dual-isotope myocardial SPECT
Naoki Yamada, Koichi Ogawa
PDF   Abstract
In simultaneous 123I/99mTc SPECT study the images reconstructed with the counts of primary photons emitted from 99mTc and 123I respectively are distorted by scattered photons and primary photons each other. In this paper, we evaluated the performance of scatter correction methods which were proposed by El Fakhri and ours with Monte Carlo simulation and experiment data in consideration of the following three points; (1) the broad energy window for data acquisition, (2) the width of the narrow energy window, and (3) the method for calculating the number of primary photons. In this simulation, we used the MCAT phantom and reconstructed by OS-EM method. And the evaluation of performance was investigated to calculate the mean squared error in the reconstructed images. In this experiment, we set six ROIs and evaluated the performance by measuring the sum of the value in each ROI. The results showed that both methods were fairly effective in separating 99mTc and 123I accurately and our method was slightly superior to their method.
Some Considerations on the Natural Element Interpolations
Keitaro Ono, Hiroshi Takeda
PDF   Abstract
In solid mechanics, finite element method(FEM) is well-used interpolation scheme. On the other hand, natural element method(NEM) is lately developed interpolation scheme. In NEM, natural neighbour co-ordinates(Sibsonian interpolation), which are based on the Voronoi tessellation and Delaunay triangles ,are an appealing choice to construct meshless interpolants. In this paper, new interpolation scheme (Non-Sibsonian interpolation) of the NEM and practical interpolation functions are reviewed for the purposes of the understanding of the features, the features, the construction of the computational algorithm and the applications of the practical problems.
Numerical Simulation of Crashworthiness of Aircraft Cabin Structures
Takefumi Hosokawa, Ikuo Kumakura, Masakatsu Minegishi, Kazuo Iwasaki, Hiroshi Takeda
PDF   Abstract
While the rate of air accident has not been improved for more the 15 years, the number of accidents will be expected to increase in future. In case crash accident of aircraft, it is important to reduce the impact load to passengers bellow the allowable level of the human body. In this research, the behavior of the aircraft fuselage structure in crash condition is numerically an alyzed by using ANSYS/LS-DYNA, and the results are compared with experimental results. The correlation between analysis and experiments are improved by introducing some assumptions on material constants. In this study, it is shown that our numerical models are applicable to predict crash behavior of aircraft fuselage structures in crash condition.
Runoff Analysis Considering Land Use Change with Detailed Digital Information
Takehiro SAKAI, Koji KODERA, Yasumiti OKA
PDF   Abstract
In this study, by applying Detailed Digital Information to distributed runoff model, stormwater runoff is analyzed in upper and middle Tsurumi River basin. The obtained result shows that the simulated hydrograph agrees well with the measured one, although further examination of the method for estimating effective rainfall and the evaluation of runoff control effect is needed. Furthermore, the result shows a change in the discharge with the expansion of the impervious area by using the 1974-1994 Detailed Digital Information land use data in every 5 years.
Three-Dimensional Stress Analysis of Ground Anchorage for Retaining Frame on Slope
Hirohisa Ohki, Norio Takeuchi
PDF   Abstract
In this paper, it carried out three-dimensional stress analysis of the ground anchorage for the retaining frame on the slope. The construction method of retaining frame on slope investigates retaining frame of lattice-type at the face of slope, and it objects to prevent weathering, erosional and collapse. Also it’s covered with vegetation and concrete on retaining frames, and it combined use of ground anchorage and reinforced steel method is more effective. Therefore it aim at making clear stress condition of the retaining frame on slope. As a result of stress analysis, it obtained when it carried out loading, stress value of concrete on face of boundary between ground and concrete was maximum, and also edge of retaining frame on slope was minimum. As regard as displacement, reasonable result can be obtained.
The Visual Perception of the Vibration Premised the View of the Skyscrapers
Kenji Hara, Tiho Inomata, Yuka Miyosi, Takeshi Goto
PDF   Abstract
The strong winds cause two kinds of the long cyclical and horizontal vibration that is the roll vibration and the twist vibration for skyscrapers. The study in the physical response and the evaluation in terms of residential evaluation for the roll vibration of them is made, but this standards and guides are aimed at only evaluation in the physical perception. The study examines the influence of the view for the evaluation of the vibration and the difference of the evaluation when the persons perceive the vibration by the visual information from view in the skyscrapers.
Revolution of Information Technology Education Online Computer Test and Report in Economics and Management Science
Kimihiko Goto
PDF   Abstract
This study has been executed to realize the following targets of education of modern economics, etc.
1 Quantitative analysis and forecast of economy based on current data and information on capital, foreign exchange, and money market obtainable through online internet devices.
2 Execution of Online Computer Test (OLC) and Report (OCR) to provide students with motivation and interest in IT education.
3 Marked to Market (MTM) Accounting of Derivatives which is now required in Japan as generally accepted accounting procedure.
Elasto-Plastic Damage Growth Analysis of Porous Media
Ryousuke Uchida
PDF   Abstract
Constitutive relation of porous media is considered from the viewpoint of damage mechanics. For the isotropic damage porous media, the constitutive equation was developed within the framework of the thermodynamic theory. In consequence, it is confirmed that isotropic damage concept is a valid method for describing a mechanical behavior of discontinuous porous media within the framework of the continuum mechanics.
Analysis of Airs Flow
Norimichi Ishida
PDF   Abstract
Computer-aided analysis techniques have revolutionized enginnering design in several important areas, especially in the field of structual analysis. Computational Fluid Dynamics(CFD) techniques are now exerting a similar influence on the analysis of fluid flow phenomena. STAR-CD is a poweful CFD tool for thrmo fluids analysis. PRO-MODELER is one of pre-processor of STAR-CD. This article explains the analysis of airs flow through PRO-MODELER.
Nth Dimensional Bi-Orthogonal Wavelets Transform and Its Applications
Sawa Matsuyama
PDF   Abstract
This paper describes that key idea to introduce wavelets transform, one-.two- and. three-dimensional wavelets transforms are introduced by means of Daubechies 2nd order base function. Finally, nth order bi-orthogonal wavelets transform algorism is derived in terms of tensor notation. As a result, it is clarified the mathematical as well as physical meaning of the discrete wavelets transform. Thus, this paper suggests that various signal and image processing problems can be carried out by the discrete wavelets transform.
Regular Polyhedra and Archimedean Polyhedra Visualized by VRML
Sawa Matsuyama
PDF   Abstract
This paper proposes the numerical method which visualizes Regular polyhedra and Archimedean polyhedra used by VRML (Virtual Reality Modeling Language). VRML is an effective representing language for static and animated dynamic 3D objects. VRML browsers, as well as authoring tools for the creation of VRML files, are widely available for many different platforms. The method can be applied to the visualizing of the various solid.