JaLCDOI 10.18926/15434
FullText URL Mem_Fac_Eng_OU_28_1_27.pdf
Author Totsuji, Hiroo| Tachibana Hiroyuki| Fujimura Hidenori| Nara, Shigetoshi|
Abstract The ground states of interacting electrons in coupled quantum wires are analyzed on the basis of the density functional theory. The exchange-correlation potential is calculated from 'exact' results given by the Green's function Monte Carlo method in two and three dimensions. It is shown that the critical density signifying the change from symmetrical to asymmetrical ground state is weakly dependent on the details of the exchange-correlation potential. These critical values are compared with the result of the three-dimensional analysis for a single wire.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 27
End Page 38
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307565
JaLCDOI 10.18926/15432
FullText URL Mem_Fac_Eng_OU_28_1_1.pdf
Author Nara, Shigetoshi| Miho Shigeru| Totsuji, Hiroo|
Abstract The structural stabilities of bulk Si, Ge, and GaAs are discussed based on the total energy evaluated by the summation of the band structure energy and the short-range repulsive potential between ions. The band structure energy is calculated by means of the simple tight-binding method. The tight-binding parameters are determined so as to fit to the results of a pseude potential calculation and Harrison's model is employed to include the influence of lattice deformation. The short-range-force is assumed to be of the exponential form and parameters are determined so as to reproduce an experimental value of bulk modulus. This treatment qualitatively well describes structural properties in spite of the simple computational procedure and roughly gives the known variation of the total energy for a <100> uniaxial strain. This method is able to be applied to an investigation of the structural stabilities of superlattices, for example, a strained layer superlattice consisting of hetero-semiconductors.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 1
End Page 25
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307238
JaLCDOI 10.18926/15418
FullText URL Mem_Fac_Eng_OU_26_1_51.pdf
Author Totsuji, Hiroo| Shirokoshi Hideki| Nara, Shigetoshi|
Abstract Variable shape molecular dynamics is formulated for the one-component plasma and the structural transition from the fcc lattice to the bcc lattice has been observed. It is emphasized that the condition of constant volume should be imposed when deformations of periodic boundary conditions are taken into account.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-11-30
Volume volume26
Issue issue1
Start Page 51
End Page 59
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307555
JaLCDOI 10.18926/15403
FullText URL Mem_Fac_Eng_OU_27_2_19.pdf
Author Nara, Shigetoshi| Totsuji, Hiroo|
Abstract Numerical simulations of a single layer recurrent neural network model in which the synaptic connection matrix is formed by summing cyclic products of succesive patterns show that complex dynamics can occur with the reduction of a connectivity parameter which is the number of connection between neurons. The structure in these dynamics is discussed from the viewpoint of realizing complex function using complex dynamics.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-03-25
Volume volume27
Issue issue2
Start Page 19
End Page 40
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307451
JaLCDOI 10.18926/15395
FullText URL Mem_Fac_Eng_OU_27_1_65.pdf
Author Nara, Shigetoshi| Hara Yuji| Totsuji, Hiroo|
Abstract Quantum mechnical electron wave transfer between two quantum wires which are weakly coupled via a thin potential barrier is considered. The total electronic states are calculated with both analytical ( no field case ) and numerical methods ( under applied electric fields ). The transfer efficiency is evaluated for several specified cases of geometrical structures, potential barrier heights and the externally applied electric field. Estimated trasfer time is of the order of one picosecond in typical mesoscopic structures. The model in this paper can be used to determine important structure parameters for experiments on electron directional coupler controled by external elctric field.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1992-11-25
Volume volume27
Issue issue1
Start Page 65
End Page 79
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307405
JaLCDOI 10.18926/15394
FullText URL Mem_Fac_Eng_OU_27_1_55.pdf
Author Totsuji, Hiroo| Tachibana Hiroyuki| Hashimoto Seiji| Nara, Shigetoshi|
Abstract The ground state of a system of electrons accumulated in a pair of coupled symmetric quantum wires is analyzed on the basis of density functional theory. It is shown that, in a domain of physical parameters, electrons are localized in either of wires. The main contribution to the total energy of this system comes from the Hartree energy, or the electrostatic energy, and the exchange-correlation energy between electrons. The ground state is determined by a competition between these contributions: We have symmetric electron distributions when the Hartree energy dominates and asymmetric (localized) states are realized in the opposite case. This kind of simple system with bistable electronic states may be applied to semiconductor memory devices.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1992-11-25
Volume volume27
Issue issue1
Start Page 55
End Page 64
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307892
JaLCDOI 10.18926/15381
FullText URL Mem_Fac_Eng_OU_30_1_75.pdf
Author Totsuji, Hiroo| Inoue, Yoshihiko| Kishimoto, Tokunari| Totsuji, Chieko| Nara, Shigetoshi|
Abstract Molecular dynamics of the Yukawa system, the system of particles interacting via the Yukawa or the screened Coulomb potential, are formulated for various statistical ensembles and external conditions. The Yukawa potential smoothly interpolates the long-range Coulomb and the short-range interactions by adjusting a single parameter, the screening length. In order to reduce the effect of boundaries, the periodic boundary conditions are imposed and the deformations of the fundamental vectors of periodicity are taken into account. Ewald-type expressions for interaction energy, force, and kinematic pressure are given explicitly.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-12-28
Volume volume30
Issue issue1
Start Page 75
End Page 87
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307479
JaLCDOI 10.18926/19648
FullText URL Mem_Fac_Eng_OU_33_2_1.pdf
Author Omura, Yasuhiro| Hida, Moritaka| Sakakibara, Akira| Takemoto, Yoshito|
Abstract Molecular dynamics simulation of nickel crystal under uniaxial tensile and compressive deformation was performed for single nenocrystal model and twinned nanocrystal model composed of 1550 atoms using EAM (embedded atom method) potential with the object of investigating deformation induced phase tranformation (especially twin deformation). In the case of single nanocrystal model, the evolution and development of twin deformation, (111)[11(2)], is observed under compressive loading in [001] direction, whereas either slip or twin deformation is not recognized under tensile loading. In the case of twinned nanocrystal model, twin, (111)[11(2)], decreases and disappears under tensile loading, and develops under compressive loading, It is suggested from the difference of results between single nanocrystal model and twinned nanocrystal model that it is easy for twin to induce local deformation.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 1
End Page 8
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309020
JaLCDOI 10.18926/19589
FullText URL Mem_Fac_Eng_OU_31_2_11.pdf
Author Ishii Kouta| Takemoto, Yoshito| Hida, Moritaka|
Abstract Fine particles of Ti-V alloy were prepared by means of arc method and were investigated on internal structure and phase transformation using HR-TEM and EDS. Martensite phase was observed in a particle containing comparatively low concentration of V, and ω phase was also found to exist in a nearly 15% V particle. The structure of the ω phase in the fine particle is remarkably expanded in comparison with the bulk sample, and the ω phase is unstable, so that it has disappeared in a few seconds during TEM observation.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1997-03-28
Volume volume31
Issue issue2
Start Page 11
End Page 20
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309004
JaLCDOI 10.18926/19588
FullText URL Mem_Fac_Eng_OU_31_2_1.pdf
Author Arisawa Hideaki| Song Zhi-Yi| Takemoto, Yoshito| Hida, Moritaka|
Abstract The microstructure of oxidizing magnesium at elevated temperatures has been studied using HR-TEM, SEM and EDS. Two kinds of thin magnesium specimen for TEM observation were prepared. One was oxidized after preparing TEM foil of magnesium, the other was prepared from an oxidized bulk magnesium for observing the cross-section of oxide/Mg interfacial region. In the former, several oxides(MgO) morphologies were observed depending on the temperature and time of the oxidization. The growth of needle-like oxides formed at 573K and mottled oxides formed at 773K were recognized as a remarkable phenomenon belonging to the local oxidization. These oxides were composed of poly-crystal. The thin uniform oxidization layer was also observed in all conditions. In the cross-sectional observation, the local oxide layer, nearly 300nm in thickness, on the matrix(Mg) were observed. The thin uniform oxidized layer of bulk samples was identified as a kind of modified layer (~40nm in thickness) in which the formation of HR-TEM lattice fringes were prevented by the strain due to the slight oxidization.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1997-03-28
Volume volume31
Issue issue2
Start Page 1
End Page 10
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309082
JaLCDOI 10.18926/15505
FullText URL Mem_Fac_Eng_OU_24_2_89.pdf
Author Yokohira, Tokumi|
Abstract This paper considers a test set for an ALU with look ahead carry generators(LCGs). The ALU is logically partitioned into two groups of blocks, the group of one-bit operation units and LCG group. Each group is tested in parallel and exhaustively, independent of the other. And an easily testable design is applied to several blocks for decreasing the number of the input combinations of them. Under the easily testable design, a minimum test set for each group is generated, and the upper and lower bounds for a minimum test for the ALU are derived. The difference of the lower and upper bounds is not large, and a test set whose number of test vectors is equal to the upper bound can be easily obtained as the union of minimum test sets for two groups. Hence, the union can be used as a complete and practical test set for the ALU.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 89
End Page 98
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307212
JaLCDOI 10.18926/15489
FullText URL Mem_Fac_Eng_OU_24_2_1.pdf
Author Umemoto, Masayuki| Takemoto, Yoshito| Sakakibara, Akira| Hida, Moritaka|
Abstract Fine particles of Ti-Mo alloy were prepared by evaporation. When Ti-40at % Mo alloy was evaporated on tungsten filament, fine particles of Ti contaminated with W were obtained. These particles were polyhedron in shape and 10~250nm in diameter. Average diameter and size distribution increased with pressure of argon gas (100~600 Torr). When pure Ti was placed on the Mo filament and evaporated from melt down of heated Mo filament in helium gas, fine particles of pure Ti and of Ti-Mo alloy were obtained. In this case, Ti particles were of indeterminate form and of several tens nm in diameter, and their diffraction pattern was of common α-Ti. On the other hand, composition of the Ti-Mo particles was determined to be 18at % Mo by an analysis of EDX. Structure of Ti-Mo particles could not be determined because their diameters were more than 600nm. The temperature of Mo filament, for the most part, was about 1800℃, and there pure Ti particles were produced. The temperature of the fused part of the filament was locally higher than 2600℃, and there Ti-Mo particles were produced. Fine structures of contact region among some Ti particles were observed with HRTEM.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 1
End Page 9
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307765
JaLCDOI 10.18926/15453
FullText URL Mem_Fac_Eng_OU_28_2_13.pdf
Author Kusumoto, Hisao| Hida, Moritaka| Sakakibara, Akira| Nishida, Norihide| Takemoto, Yoshito| Yamada, Masuo|
Abstract The strain in Si substrate induced by locally ion-plated thin film of TiN was observed by X-ray topograph (Lang technique). Circular TiN film was deposited on one side of the Si surface. In all topographs the highest blackness attributed to kinematical diffraction effect occurred at the film edge. Rosette pattern with four-lobes was observed around the film. Blackness as a whole increased with the film thickness. Strain was observed in the depth direction of substrate by limited projection method. When the slit width was narrowed, the kinematical images disappeared, and white images appeared at the film edge. All the contrast disappeared when the TiN film was completely removed in boiling HNO(3). The strain induced by the film deposition was proved to be elastic.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-03-15
Volume volume28
Issue issue2
Start Page 13
End Page 20
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307150
JaLCDOI 10.18926/15448
FullText URL Mem_Fac_Eng_OU_28_2_1.pdf
Author Takemoto, Yoshito| Sakakibara, Akira| Hida, Moritaka|
Abstract Fine particles of Ti-Mo alloy have been prepared by means of arc method, and investigated on internal structure and phase transformation using HR-TEM and EDS. Martensite phase was observed in a particle containing comparatively low concentration of Mo, and ω phase was also found to exist in a nearly 14 % M0 particle. The structure of the ω phase in the fine particle is expanded and remarkably unstable in comparison with the bulk sample, so that it has disappeared in a few seconds during TEM observation. Moreover, the β structure of Ti-Mo particles has changed to the unusual fcc phase with irradiation of a strong electron beam.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-03-15
Volume volume28
Issue issue2
Start Page 1
End Page 7
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307644
JaLCDOI 10.18926/15397
FullText URL Mem_Fac_Eng_OU_30_2_1.pdf
Author Takemoto, Yoshito| Hida, Moritaka| Sakakibara, Akira|
Abstract The mechanism of brittle fracture in Ti-14mass % Mo alloy aged for 1x10(6)s at 623K was studied using transmission electron microscopy (TEM) and dynamic hardness test (DHT) on the structure deformed by means of tensile elongation at elevated temperature or cold rolling. Many band products were observed by TEM in either deformed specimens. These band products were identified to neither slips nor twinning bands, moreover, they were different from α , α ' and α " phases. The band product consisted of β phase and granular unknown phase which was transformed by deformation from ω phase. The newly discovered phase, named β" phase, in the band products had a body-centered triclinic structure. The β" was similar to the ω zone with respect to the morphology and the concentration of Mo, but it resembled β in structure. The result of DHT on the band products and the matrix showed that the band products were softer than the matrix. It is suggested that the band products are easily deformed because of the disappearance of obstacles such as ω phase, and consequently behave like paths to lead cracks preferentially.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1996-03-29
Volume volume30
Issue issue2
Start Page 1
End Page 7
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307225
JaLCDOI 10.18926/15466
FullText URL Mem_Fac_Eng_OU_24_1_1.pdf
Author Yoshida, Akira| Ohue, Yuji| Fujii, Masahiro|
Abstract To clarify the effects of a drive system lubricant additive upon rolling fatigue of rollers manufactured from carburized and hardened steel, three types of oil were used as lubricants: one mineral base oil and the other two mineral base oils to which an S-P additive package and ATF additive package were added, respectively. These specimens were tested for sliding/rolling fatigue and examined for failure on the surface, rolling fatigue strength, and other properties. Roller surface temperatures and inter-roller frictional coefficients were found scarcely affected by the type of oil used. Irrespective of the difference in oil type, failure on the surface was found to be entirely spalling attributable to cracks generated in the subsurface. The depth at which spalling cracks had taken place was found nearly coincident with the depth at which a ratio of reversing orthogonal shear stress to hardness had amplitude A(Tyz/Hv) maximized. These depths were larger as Hertz stress became more prominent. Nevertheless, they were found hardly affected by the type of oil. Although rolling fatigue strength did not show a significant difference dependent upon the type of oil, it may be said that fatigue life would be somewhat negatively affected by an extreme pressure coated film with a content of sulfur and phosphorus.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1989-11-29
Volume volume24
Issue issue1
Start Page 1
End Page 12
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307588
JaLCDOI 10.18926/14134
FullText URL Mem_Fac_Eng_39_1_1.pdf
Author Vladimir I. Klochikhin| Fujii, Masahiro| Yoshida, Akira|
Abstract Improvement of wear resistance and durability of machine elements with sliding friction pairs is the important tribological problems. The wear resistance has been determined with many configurative parameters, technological parameters, and operational parameters. In this study kinematics of cylindrical joint (CJ), whose motion is reciprocating and rotating, and influence of various parameters on wear resistance of friction pair was investigated.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2005-01
Volume volume39
Issue issue1
Start Page 1
End Page 6
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308183
JaLCDOI 10.18926/15498
FullText URL Mem_Fac_Eng_OU_25_1_99.pdf
Author Nishigaki, Makoto| Takeshita, Yuji| Kono, Iichiro|
Abstract In this paper, a numerical procedure of determining hydraulic properties in multilayered aquifers are presented. From pumping test data in multilayered aquifers, the coefficient of permeability and specific storage for each aquifer are determined by using a combination of finite element analysis and nonlinear least-squares optimization technique. This study especially points out necessity of stress-flow coupling analysis to explain the behaviors of pressure head in multilayered aquifer during pumping test. As a example, practical pumping test data were evaluate and the coefficients of permeability and specific storage of aquifers and aquitard were obtained.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 99
End Page 109
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307452
JaLCDOI 10.18926/15483
FullText URL Mem_Fac_Eng_OU_24_1_107.pdf
Author Kohno, Iichiro| Nishigaki, Makoto| Takeshita, Yuji|
Abstract The numerical feasibility of determining soil water retention and hydraulic conductivity functions simultaneously from one-dimensional transient flow experiments in the laboratory by parameter estimation method is evaluated. Soil hydraulic properties are assumed to be represented by van Genuchten's closed-form expressions involving two unknown parameters: coefficients α and n . These parameters are evaluated by nonlinear least-squares fitting of predicted and observed pressure head with time. Gravity drainage experiments are performed for Toyoura standard sand to evaluate the adequacy of this proposed method.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1989-11-29
Volume volume24
Issue issue1
Start Page 107
End Page 114
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307749
JaLCDOI 10.18926/15451
FullText URL Mem_Fac_Eng_OU_22_45.pdf
Author Kohno, Iichiro| Nishigaki, Makoto| Takeshita, Yuji|
Abstract There are two classifications of the mechanism of levee failure caused by floods; local seepage failure and progressive failure. The fundamental causes of levee failure produced by piping and erosion were studied and the safety of river leves during floods evaluated in terms of soil machanics. The critical hydraulic gradient and the process of progressive failure were obtained from one- and two- dimensional model experiments for piping and erosion. Problems inherent in and preventive measures against levee failure are discussed. In particular, effects of the Tsukinowa method, the most representative Japanese flood fighting method, were studied experimentally and improvements proposed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1988-03-31
Volume volume22
Start Page 45
End Page 62
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307536