vol.11 (1998)

Bulletin of Computational Science Research Center
Vol.11, 1998 ISSN 0913-8420 Published March 31, 1998

CFD Analysis of Flow in Ultra Highly Loaded Turbine Blad
Wataru Hirohata, Hoshio Tsujita, Shimpei Mizuki
PDF   Abstract
In this study, highly loaded turbine blade is analyzed by a numerical method for the three-dimensional incompressible viscous flow. The governing equations with the standard к – ε model are solved in the physical component tensor form in a boundary-fitted coordinate system. The geometries of ultra highly loaded blades posses the limiting turning angles of about 160 degrees. As the results, it is found that the mechanisms of loss generation govern the behavior of secondary flows and the growth of boundary layer.
Numerical Analysis of Swirl Flow in Bubble Elimination Device
Yutaka Tanaka, Hikofumi Yamamoto, Kazuyoshi Arai, Ryushi Suzuki
PDF   Abstract
Bubbles in working fluids have much influence on the performance of hydraulic systems and cause some troubles. It is an important technical issue to eliminate the bubbles from the oil because of preventing a degradation of the oil and a damage of hydraulic components- Recently, a device to eliminate bubbles in oils by a swirl flow has been developed. In this paper, a numerical analysis of the swirl flow in the developed bubble elimination device has been carried out. Effects of dimensions for the bubble elimination device are discussed and the principle of the bubble elimination is verified from the obtained numerical results.
Control of Telerobotic System with Communication Delay
Yusuke NEMOTO, Yutaka TANAKA
PDF   Abstract
A communication delay is an important problem for telerobotic projects. A delay time for communication link depends on a medium and a load for communication. Therefore it is difficult to control feedback systems for the communication link between a working space and the operating station. In this research, a working environment with consideration of transmission of time delay has been studied and a validity of a compensated time delay for the communication link has experimentally investigated.
Mutual Diffusion Near the Critical Point of Two Dimensional Lennard-Jones Solution
Yosuke Kataoka, Ken-ichi Ago
PDF   Abstract
Measuring diffusion coefficients of acetone, benzene in supercritical carbon dioxide by the Taylor dispersion method, we observed that the diffusion coefficients approached zero near the critical pressure of the mixture. Some papers on the anomalies of diffusion coefficient near the critical point have been reported. Molecular dynamics simulations were carried out in order to reveal the mechanism of critical diffusion. As a result, we found that diffusion drop near the critical point was related to the high concentration fluctuation near the critical point.
Transient Analysis of DC/DC converter taking into account the magnetic hysteresis
Nobuyuki Kobayashi, Seiji Hayano, Yoshifuru Saito
PDF   Abstract
DC/DC converters are widely used in the various electronic devices, such as large and small computers. Since all of switching DC/DC converters utilize the magnetic energy stored in the magnetic materials, then it is essentially accompanying the iron loss. In order to reduce the iron loss, various new magnetic materials have been proposed. However, it is intrinsically difficult to remove the magnetic saturation of the magnetic materials. Sometimes* this leads to the asymmetrical magnetization, i.e. magnetically saturated operation. Particularly, transient state falls into the magnetically saturated operations. In the present paper, we carried out the numerical simulation in order to examine the basic transient characteristics of full-bridge type and fly-back type DC/DC converter taking into account the magnetic hysteresis loops.
A Feasibility Study on GIS(Geographical Information System) Adptation for Hydrology
Hiroei NAKAMURA, Kanae SUZUKI, Nobuhiko KOBAYASHI, Mikio SHINKAWA, Koji KODERA, Takanobu N1SHIYA, Yasumichi OKA
PDF   Abstract
Hydrological studies need to use many geographic informations of river basins which are complicated to have many various features. Applications of now OIS Icclunqncs are required to make data bases of hydro- graphy of river basins and to study many liydrologicnl ploblems such as runoff analysis . In litis study , we used PC- based GIS software ArcVicw3.0a to make a Spacial Data Base of the Asakawa River Basin , Tokyo , Japan , and estimntcd its validity for runoff analysis by a distribution-type- runoff-modcl. The result of our study shows thai there arc sonic ploblems on data exchanging between different softs , but that PC-based GIS software is sufficient enough for runoff analysis aitd other hydro logical studies.
Correlation between nuclear densities and incompressibility in relativistic mean field theory
Satoshi Yosida
PDF   Abstract
The structure of nuclear matter have been studied theoretically in order to study the nuclear force which interacts between nucleons and the structure of nucleus and so on. The nuclear matter is in the infinite system and the density of it is constant. The reason why we use nuclear matter is that the nuclear density is constant in the center of heavy nucleus, and the structure of nuclear matter seems to be close to that of neutron star. We use the incompressibility to describe the state of nuclear matter. The value of incompressibility is determined by the energy of giant monopole resonaace (GMR) of nucleus. However the value has not been determined accurately yet. because it is difficult to measure the energy of GMR. Furthermore it is impossible to measure the energy of GMR of unstable nucleus of which the ratio between neutron number and proton number is larger than that of stable nucleus, such as neutron star. Therefore I start to study the relation between incompressibility and unclear surface diffuseness in relativi3tic mean field theory as trial to look for another way to determine the value of incompressibility experimentally.
Ab Initio Calculation for Benzylic Cations
Kazuhide Nakata, Kouichi Nakajima, Kyuji Ohta, Mizue Fujio, Masaaki Mishima, Yuho Tsuno, Kichisuke Nishimoto
PDF   Abstract
Structures of 20 kinds of α-subsliluted benzylic cations and their conjugate base, which cover a wide variation of the stability, were optimized by means of nb initio molecular orbital method at the RHF/6-3IG* level. Total energies were calculated at the MP2/6-31 G*//RHF/6-3IG* + ZPE (scaled 0.9) level. Calculated relative proton affinities of conjugate bases agreed well with the cones ponding basicities in the gas phase. The obtained theoretical indices associated with the resonance interaction, such as population, bond order, and bond length were compared with the resonance demand parameter (r value) of corresponding solvolysis systems, that were given in the Yukawa-Tsuno substituent effect analysis. The r value was linearly correlated with the theoretical resonance indices. The relation of each theoretical index and the r value agreed completely with the prediction by the electronic theory. This provides theoretical support that the r value is a good parameter indicating the degree of resonance interaction between benzylic pπ-orbital and benzene π-system.
Coulombic three-body bound state problems in the framework of Faddeev-Separable-Expansion method
Yasuro Koike
PDF   Abstract
Anew method for solving Coulombic three-body bound states is proposed. It will be shown that a standard method, Faddeev-Separable-Expansion method, for the three-body problems can be used for Coulombic three-body bound states, even though Coulomb interaction is not of finite range. A numerical example for a model three-body problem is given which suggest this method is a promising application field for computational physics.
A method of sable calculation of frequency characteristics of a layer medium
Kyoji Akiyama, Yuko Oguchi
PDF   Abstract
This paper discusses bow to calculate stably frequency characteristics of a layered medium Variety of method of calculation based on Thomas-Haskell matrix formalism have been proposed and investigated. These method, however, fell into the numerical instability in the high frequency range and/or oblique incidences of waves, Kennet and Kerry proposed an excellent algorithm for computing theoretical seismograms by the concept of reflection and transmission matrices of the wave at each layer to solve the numerical instability problem. Here, we propose a simple algorithm that is not require complex calculation modify their algorithm, and develop a computing program that can be run in a handy personal computer It have been shown that the method is useful to calculate stably frequency characteristic through wide range of frequency.
Wavelet Analysis of 111 Posed Linear Systems
Norimichi ISHIDA
PDF   Abstract
This paper proposes a new methodology solving for the ill posed linear systems. Key idea is that the system matrix is regarded as an image data. Applying the discrete wavelet transformation to this system matrix yields an approximate inverse matrix. Thus, we succeeded in solving the ill posed linear systems. An example concerning with the inverse problem in magnetos tat ic fields demonstrates the usefulness of our methodology.
Improvement of Image Matrix Method
Norimichi ISHIDA
PDF   Abstract
Previously, We have proposed an image matrix method solving Tor the ill posed system of equations. In the present paper, we propose a methodology for improving the solutions obtained by means or image matrix. Key idea is adding the zero column and row vectors to the system matrix. This makes it possible to remove the noise caused by data compression. Thus, We have succeeded in obtaining the dramatically improved solutions or ill posed system of equations.
Aproximately Analysis of Vandermonde Type Linear Systems
Harumi Iwasak, Yuko Oguchi, Yoshifuru Saito
PDF   Abstract
Vandermonde type linear Systems are encountered in the least squares, Lagrangian interpolations and so on. Sometimes, it is difficult to evaluate an inverse matrix of the Vandermonde type system matrix. Namely, Vandermonde type system matrix becomes an singular matrix. This paper proposes one of the breakthrough methodologies for evaluating such an ill-posed system matrix employing wavelet transformation. A typical Vandermonde type of linear system occurred in inverse problem of magnetos tatic fields is successfully solved by our new approach.
Approximately Axialysisis to Linear System used Wavelet Tramaformation, No. 2
Harumi Iwasski, Yuko Oguchi, Yoshifuru SAITO
PDF   Abstract
In the present paper, an approximate solution methodology employing the wavelet transformation for the huge linear system is proposed. A linear system is transformed into a wavelet spectrum space, and an approximate solution in wavelet spectrum space is evaluated from a reduced small size system including the mother wavelet spectrum. Inverse wavelet transform to this spectrum solution yields an approximate solution. Several examples demonstrate the usefulness of our methodology.
Linear Space Analysis of the Literature
Harumi Iwasaki, Yoshifuru Saito, Kenji Miyazawa, Kiyoshi Horii, Noriko Kaneda
PDF   Abstract
In the present paper, we propose a new methodology for analyzing the literature based on the linear space theory. At first, we classify the conversation sentences used in the story of “Kusamakura” into three kinds of styles. Secondly, three dimensional normalized orthogonal vector space is constructed from three kinds of conversation styles by means of the Gram-Schmidt process. Third, discrete wavelets transform is applied to these three dimensional normalized orthogonal conversation vectors. As a result, it is revealed that a vector composed of the conversation vectors at each chapter in “Kusamakura” is spirally rotating with sinusoidally modulated magnitude. Thus, we have succeeded in analyzing the structure of “Kusamakura” using linear space theory.
The Vector Data Noise Reduction by the Wavelets
Sawa Matsuyama, Yuko Oguchi, Yoshifuru Saito
PDF   Abstract
One of the distinguished properties of the wavelet transform is that the major dominant factors can be extracted from the data. Major applications of the wavelet transform have been focused on the waveform analysis and image data compression. In the present paper, we apply this property to the vector data. As a result, we have succeeded in reducing the noisy vector data into noise free fine data.
Applications of the Wavelets to the Oceanographic and Meteorological Data
Sawa Matsuyama, Yuko Oguchi, Yoshifuru Saito
PDF   Abstract
Major applications of the wavelet transform have been focused on the waveform analysis and image data compression. One of the distinguished properties of the wavelet transform is that the major dominant factors can be extracted from the data. In the present paper, we apply this property to the meteorological data and oceanographic data. As a result, we have succeeded in compressing these data.