vol.12 (1999)

Bulletin of Computational Science Research Center
Vol.12, 1999 ISSN 0913-8420 Published March 31, 1999

Numerical Analysis of Swirl Flow in Bubble Elimination Device (Performance Evaluation of Bubble Elimination)
Hikofumi Yamamoto, Yutaka Tanaka, Kazuyoshi Arai, Ryushi Suzuki
PDF   Abstract
Bubbles in working fluids greatly influence the performance of fluid power systems. Recently, one of the authors has developed a novel device for bubble elimination capable of eliminating bubbles and decreasing dissolved gases using swirl flow. This device is called the “Bubble Eliminator”. Using the bubble eliminator will enable the fluid power system to perform better. In this paper performance evaluation of a bubble eliminator is investigated through numerical analysis of the swirling flow in the device. The swirl flow pattern and pressure distribution in the bubble eliminator are calculated by a three-dimensional numerical analysis for both single-phase and multi-phase flow.
Haptic Interface for Enhanced Sensation of Spatial Distribution Data
Tetsumi Aono, Yutaka Tanaka
PDF   Abstract
problem that human comprehensibly communicate 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 interaction sensation for representation of the data. The purpose of this study is to give new insights to the comprehension of the science and technology data, when we intuitively understand much information. Stereo vision and haptic sensation are linked with the conventional technique of displaying the spatial distribution data. The word “Haptic” means tactile and/or the sense of touch. This paper describes a surface model displaying system applied the virtual reality technology. The surface model is the spatial distribution data which defines surfaces shape of the object. It is experimentally verified that the data sensualization system enhances human sensation.
Telecommunication of Computer Assisted Instruction System (Interactive Education for Teacher and Students)
Yutaka Tanaka, Hirotsugu Nakai, Sawa Matsuyama, Harumi Iwasaki
PDF   Abstract
Recently Computer Assisted Instruction (CAI) systems have been practiced in wide variety of education and training. A conventional CAI system has some problems as follows: (1) Data of teaching materials flow uniquely from a teaching material data-base to students, therefore the students are not interact with the teacher. (2) The cost of the teaching material is too expensive and distribution and/or renewal for the teaching material increase the work of teachers. (3) A story for teaching materials has a lack of flexibility. The purpose of this study is to develop a novel CAI system that is consist of a teaching material with HTML and Virtual Reality technologies, class by using Microsoft Net Meeting, an image of a CCD camera, and the network connection such as the Internet or LAN. Performance of the developed CAI system has been estimated by questionaries for subjects.
Numerical Simulation of Transonic Flow in Compressor Cascades
Toshiyuki Uchibaba, Yasumasa Takada, Kei Akasaka, Hoshio Tsujita, Shimpei Mi, Shimpei Mizuki
PDF   Abstract
A High performance with light weight and low fuel consumption is the challenge for modern aircraft engines. Thus, a transonic compressor system with a high pressure ratio is necessary. However, a total pressure loss induced by shock-wave/boundary-layer interaction occurs in the transonic flow in a highly loaded compressor. In addition, severe boundary-layer separations induced by the shock-wave/boundary-layer interaction cause also the blade buffeting and the unsteady flow. Therefore, many experiments for the shock-wave/boundary-layer interactions were carried out during the past decade. However, the shock-wave/boundary-layer interactions have never been accurately predicted, until now. Thus, in this study the 2-dimensional compressible Reynolds-averaged Navier-Stokes equations were solved to analyze the detailed flow and the structures on the shock-wave/boundary layer interaction in the transonic compressor cascades. The computed results were compared with the experimental data for the V103-220 compressor cascades which consists of NACA65 blades and the good agreement between them was obtained.
Analysis of Liquid - Vapor Interface of Water used Molecular Dynamics Method
Yousuke Kataoka, Tadaaki Mashimo
PDF   Abstract
Estimating a condensation coefficient of water by a flux correlation method, we found that molecular exchange played an important part in the condensation coefficient. We carried out molecular dynamics simulation for water at the temperature of 350K to investigate the properties of molecular exchange. Ag a result, we found that molecular exchange was caused not by the collision between an incoming and an outgoing molecule but by the indirect interaction between an incoming and an outgoing molecule.
Posture Determination Method of Human-Type Redundant Manipulator
Yoshimiti UMEKI, Kazuyuki TAKAHASHI, Isamu MATSUMURA, Junya TATSUNO, Hisato KOBAYASHI
PDF   Abstract
This article reports on a method for avoiding singular posture in the movement of robots’ hands. When we control robotic manipulators by vision servomechaniam, the robots’ hand sometimes fall into so called “singular posture,” which causes irregular motions. This report includes a basic consideration on kinematics and inverse kinematics of the robot considered here., a detailed analysis of the singular posture and a way to avoid the singular situation.
A study of Current Viewer -Deconvolution of the current distributions-
Makoto Aoki, Seiji Hayano, Yoshifuru Saito
PDF   Abstract
Previously, we have proposed a current viewer in order to evaluate the current distributions in the electronic circuits. As an initial experiment, we have succeeded in obtaining the good results. However, it has been essential that the evaluated results include more or less the space as well as frequency characteristics of a current viewer coil. In the present paper, we try to remove the characteristics of viewer coil by means of the decomvolution method. As a result, we have succeeded in obtaining the fairly improved results.
An analysis of the electromagnetic field distributions for a ferrite toroidal core
Nobuyuki KOBAYASHI, Seiji HAYANO, Yoshifuru SAITO
PDF   Abstract
This paper proposes a finite element method using the magnetic current density as an input vector for solving the electromagnetic field problem having an open boundary. This method is based on the strategic dual image forcing an open boundary to close for the finite element solution of open boundary problem. In this paper, we analyzed the electromagnetic field distributions of inside and vicinity of a ferrite toroidal core taking into account the magnetization characteristics and estimated the hysteresis loops as well as skin effects.
A study of coil Impedance vs. frequency characteristic analysis having arbitrary geometrical shape
T.Takano, S.Hayano, Y.Saito
PDF   Abstract
Coil impedance computation having arbitary shape is relatively difficult task, because the inductance as well as resistance are not simple functions of the geometrical parameters but frequency. In the present paper, we propose a new semi-analytical approach to compute the impedance vs. frequency characteristics of the coil having arbitrary shape. Any coils having complex geometrical shape can be divided into small conductors having simple geometrical shape. Applying analytical formula to each of the small subdivided conductors, each of the inductances and resistances is easily calculated by an analytical approach. Combining entire inductances and resistances taking into account the mutual inductances yields an equivalent circuit of the original coil having complex geometrical shape. Establishing and solving a set of circuit equations about this equivalent circuit make it possible to evaluate the impedance vs. frequency characteristics of the coil. Simple examples verify our proposed methodology.
Inverse Analysis Strategy to Searching for the Radioactive Source Distributions
Amane Takei, Seiji Hayano, Yosifuru Saito
PDF   Abstract
conventional numerical iterative approaches. We have applied our vector type SPM method to searching for the radioactive field source and to demonstrating the three dimensional radioactive field distributions. As a result, we have succeeded in evaluating the unique radioactive field source and three dimensional vector field distributions from the locally measured radioactive fields.
Wavelets Analysis applied to the Ill-posed Linear Systems
Ken Nakajima, Seiji Hayano, Yosifuru Saito
PDF   Abstract
In the present paper, we propose a wavelets approach solving for the ill posed linear system of equations. Key idea is that the two dimensional wavelets transform U applied to the system matrix and collecting the most dominant elements on the system matrix yields an approximate inverse matrix in the wavelets spectrum domain. Inverse wavelets transform of this approximate inverse matrix gives an approximate inverse matrix in the original domain. This is original concept. Thus, it is possible to obtain the approximate solution of ill posed linear systems. The method is applied to an estimation of the current distributions on a film conductor. Intensive verification shows the validity of our method.
A Study of Visualization of Electromagnetic Fields Distribution - Extraction of The Dominant Magnetic Fields -
S.Miyahara, S.Hayano, Y.Saito
PDF   Abstract
This paper proposes a methodology for visualizing the electromagnetic field distributions vicinity of the electronic devices. At first, we solve an inverse source problem in order to identify the magnetic field sources from the locally measured magnetic fields. Second, we calculate the magnetic field distributions from the estimated magnetic field sources. Third, we calculate the eddy current induced on a sheet of iron. Finally, we extract the most dominant magnetic field distributions using the 3D wavelet transform. In the present paper, basic principle and initial experiments to verify our approach are described. As a result, it is revealed that the magnetic field distributions near the electronic devices can be visualized from the locally measured magnetic fields. Further, we have succeeded in extracting the major magnetic field vectors as well as their sources by the multi-dimensional wavelet transform.
System Nonlinearity Index and its Estimation based on Volterra Series
Hirohisa Mizuta, Nozomu Inomata, kazuo Yana
PDF   Abstract
This paper proposes an index named the degree of nonliniarity (d.n) for measuring system nonliniarity. The index is defined using differences in mean squared output prediction errors by the optimal linear system and an optimized nonlinear parametric nonlinear system model. The index is normarized to take values between 0 and 1 depending on how much output variations are linearly predictable. The index is applicable to the system with additive output noise where the conventional coherence function does not work.
An Effective Finite Element Analysis with Convection of Plate like Structures
Yoshiaki Suzuki, Hiroshi Tanaka
PDF   Abstract
In the structural analysis, plate and shell like structures will be solved by the two dimensional analysis rather than the three dimensional full analysis by considering the thickness mechanical properties. In this paper we will propose simulate effective general formulation for the heat transfer problems with convection term.
A COMPUTATIONAL VISUALIZATION METHOD FOR MECHANICAL PHENOMENA
Tomokazu Tomioka, Hiroshi Takeda
PDF   Abstract
Visualization methods that are based on modern computer graphics techniques play an essential role in physical interpretation of the computational results from finite element analysis. A new algorithm is presented for effective color presentation of flow lines for scalar, vector and second order tensor variables predicted by computational analysis. This method is based on contour line representation of the streamline potential function of a given vector field.
Analysis of progressive fracture mechanism by the finite volume method
Takao Niitsu, Hiroshi Takeda
PDF   Abstract
Almost of criteria for the initiation and the development of the fracture are considered on the surface rather than the volume element. To establish the natural computational method of the fracture development phenomena, finite volume based surface integration formulation is proposed rather than finite element volume integration formulation. Proposed formulation will he converted to the standard finite element algorithm for the practical implementation.
Production of Teaching Materials for a Class on “Image Processing by Using Visual C++”
Iwao Morishita, Shuzo Matsuda
PDF   Abstract
This paper describes an example of teaching materials produced for a class on “Image Processing by Using Microsoft Visual C++.” This language was selected because of its powerfulness for implementing applications to be executed on Windows NT/95/98 machines, and also of its availability in our campus computer facilities. Since Visual C++ is not a compact language and the beginners usually feel considerable difficulties even in understanding the basic techniques, teaching materials must be designed carefully. This paper reports how the lecture series was organized, what contents were distributed to the students as printed lecture notes, and what demonstrations were presented as programming examples at the class room using a video projector. The teaching materials were used two years in a class.
Distributed Runoff Modeling with Infiltration Capacity Map using GIS
Hiroei NAKAMURA, sumiti OKA, Takanobu NISHIYA, Koji KODERA
PDF   Abstract
Recently the storm water infiltration system is gradually becoming an important part of measures to cope up with increased storm runoff. This paper describes simplified modeling methods to evaluate basin-scale effect of storage and infiltration systems for flood control. As the model developed here considered soil properties of various land use, infiltration capacity map which describes the distribution of field infiltration capacity is required. The result shows that GIS software is useful for integrate the map for runoff analysis, such as soil type, land use, and watershed. In addition, ridges and channel networks are figured using digital elevation data, and the result compares fairly good with observed data.
Anisotropic Yield Function for Hydrostatic-Pressure-Dependent Materials and Evaluation Method of Material Parameters
Tuyoshi Kaneshige, Youichi Tomioka, Hiroyuki lyoda, Hideaki Aoyanagi, Morito Kusabuka, Hiroshi Tkeda
PDF   Abstract
A new anisotropic yield function was proposed for the hydrostatic stress dependent materials. This function consists of an idea that each independent components of a stress tensor is multiplied by the arbitrary coefficient corresponding to each anisotropic principal axis. Both of a meridian of this yield surface and a shape of the deviatoric stress plane are dependent upon hydrostatic pressure. It was shown that a number of classical yield functions are derived from the proposed yield function as special cases. The material parameters included in the proposed yield function ware evaluated by using a nonlinear optimization programming method with certain constraint conditions. This method can evaluate the material parameters only by conventional uniaxial and triaxial compression tests, and do not require any difficult tests as simple shear tests or uniaxial tention tests for rock like materials. To prove the usefulness of the proposed yield function and material parameter evaluation method, the nu-merical analysis results for various anisotropic rock materials were compared with the experimental results. The conclusions are as follows;
・ the numerical results of yield strength have good agreement to the experimental results for various anisotropic rock materials,
・ the minimum yield stress occurs at an orientation angle within 30 and 45 degree to a principal axis of anisotropy,
・ an orientation angle that the minimum yield stress occurs increases according to hydrostatic pressure,
・ the ratio of anisotropy decreases acoording to hydrostatic pressure.
By this results, it was shown that the proposed yield function has good expression for the mechanical characteristics of anisotropic materials.
An algorithm of seismic phase detections by the correlation method (1)
Yuko Oguchi
PDF   Abstract
E.R.Kanasewich has proposed an effective method of phase detections to teleseismic signals. Anant and Dowl have improved the method by Varmax Norm and wavelet transforms. In this report, these algorithms were checked and arranged to be able to apply to noisy local seismic records or artificial earth’s vibrations. An example of seismic P-phase detection was shown in good agreement with the arrival time determined by the direct reading.
Cyberspaces and Spatial Structures
Tosiyasu L, Kuni i
PDF   Abstract
In the era of gl obal 24 hour net working of varieties of devices and equipment, new environments such as Jini have been proposed by different vendors. There is a lack of basic scientific research on the spatial structures of the cyberspaces thus created. From engineering view points, the situation is exactly the construction without the foundation. It poses great difficulties inconstructing the world of artificial in cyberspaces. This paper presents a simple approach to solve the difficulties.
Application of Wavelets Transform to The Vector Fields
Norimichi Ishida, Sawa Matsuyama, Yuko Oguchi, Yoshifuru Saito
PDF   Abstract
In order to remove the noisy vector fields from the raw measured fields, this paper proposes a novel approach based on the discrete wavelets transform. At first, the scalar and vector potentials are evaluated from the raw measured vector fields by combining the Helmhortz’s theorem and minimum norm methods. Second, we apply the discrete wavelets transform to each of the scalar and vector potentials. Utilizing the data compression ability of the discrete wavelets transform, noise components included in the potentials can be dramatically reduced. Intensive simulations verify the our approach and applications to the practically measured vector fields are demonstrated
Applications of the Wavelets to the Three Dimensional Magnetic Fields
Sawa Matsuyama, Yuko Oguchi, Shinichiroh Miyahara, Yoshifuru Saito
PDF   Abstract
Wavelets transform is suitable method to analysis for the various waves in time and space. Conventional wavelets transform have been mainly applied to the one and two dimensional variable phenomena, but three dimensional wavelets transform has been rarely proposed and used even if the physical phenomena always exhibit the three dimensional properties. In the present paper, we have developed a way of the three dimensional discrete wavelets transform and applied the three dimensional magnetic fields caused by an induction heating system. As a result, we have succeeded in extracting the major dominant vector components and clarified that this extraction of the major dominant magnetic fields from the raw measured vectors essentially accompanies a noise reduction function of the wavelets transform.
Three Dimensional Vector Data Noise Reduction by the Wavelets
Sawa Matsuyama, Yuko Oguchi, Yoshifuru Saito
PDF   Abstract
Wavelets transform has been mostly applied to the one- and two-dimensional wave-like phenomena. Major applications of the wavelet transform have been focused on both the waveform analysis and image data compression. One of the distinguished properties of the wavelets transform is that the major dominant factors can be extracted from the data. In this paper, we have applied this property to the three dimensional vector data. As a result, we have succeeded in extracting the major dominant vector components and reducing the noisy vector data.
Linear Space Analysis of the “Bochan” and “Sanshiro” Styles
Harumi Iwasaki, Yoshifuru Saito, Kenji Miyazawa, Kiyoshi Horii
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 “Bochan” & “Sanshiro” 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 “Bochan” & “Sanshiro” is spirally rotating with sinusoidally modulated magnitude. Thus, we have succeeded in analyzing the structure of “Bochan” & “Sanshiro” using linear space theory.
Methodology of Geographical Information Processing on Geomorphology and Hydrology -An Attempt to Measure Drainage Landforms based on Digital Elevation Model-
Daichi Nakayama, Koji Kodera
PDF   Abstract
Recent progress in computers and development of widespread spatial information enables us to use Geographical Information Systems (GIS) in earth sciences, such as geomorphology and hydrology. In general, GIS treat two kinds of data, raster type and vector type. Raster type data possess grid characteristics, and vector type data possess network ones. Satellite images and digital elevation models (DEM) are typical raster type data, and used as the basic dataset for geomorphology and hydrology. For geomorphology and hydrology, extraction of stream networks is one of important procedure to measure topographic characteristics and to construct runoff models. However, manual extraction of stream networks from topographic maps is very time consuming work. So automatic extraction of stream networks from DEM attracts attention of many researchers. Stream networks simulated from DEM are called as drainage direction matrices (DDM). DDM possess combination characteristics of grid characteristics of raster type and network one of vector type. Therefore, it is impossible to handle DDM with simple use of filter operators, which majorly used in image processing software and GIS. So we should consider both characteristics of vector and raster type data when we treat DEM and DDM. In this paper, we explain the basic algorithms to handle DEM and DDM in geomorphology and hydrology.