| JaLCDOI | 10.18926/15414 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_26_1_27.pdf |
| Author | Tomita, Eiji| Nsunge Felix Chintu| Hamamoto, Yoshisuke| |
| Abstract | Distributions of hydrogen gas concentration in a suddenly started, single shot hydrogen gas jet issuing from a 1 mm diameter injector into still air were measured using laser interferometry method. This unsteady, turbulent free jet flow has also been calculated using the two-equation, high Reynolds number version of k-ε turbulence model and hybrid scheme for treating combined diffusion and convection in the SIMPLE algorithm. The injection pressure was 0.5 MPa for which predicted and measured temporal jet tip penetration distributions indicate that the jet discharged into still air at Mach 0.25. The level of agreement between present prediction and measurement is good in some regions and poor in others. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1991-11-30 |
| Volume | volume26 |
| Issue | issue1 |
| Start Page | 27 |
| End Page | 41 |
| ISSN | 0475-0071 |
| language | 英語 |
| File Version | publisher |
| NAID | 120002307648 |
| JaLCDOI | 10.18926/15508 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_25_2_25.pdf |
| Author | Nsunge Felix Chintu| Tomiｔa, Eiji| Hamamoto, Yoshisuke| |
| Abstract | A suddenly started cold methane gas jet issuing from a 1 mm diameter orifice into still air at Mach one has been predicted using the two-equation, high Reynolds number version of k-ε turbulence model and SIMPLE algorithm which employs so called primitive variables and a hybrid scheme for treating combined diffusion and convection. Global trends of predicted radial distributions of velocity, temperature, methane concentration in the steady rear part of the transient jet and axial jet tip penetration compare reasonably well with universal profiles representing measurement for the steady jet particularly in the fully developed turbulent core and semi-empirical relation for the transient jet respectively. The prediction scheme has shown reasonably good accuracy especially in prediction of main flow parameters of a transient, high speed compressible gas jet issuing into a dissimilar surrounding gas(binary gas mixture jet). |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1991-03-28 |
| Volume | volume25 |
| Issue | issue2 |
| Start Page | 25 |
| End Page | 38 |
| ISSN | 0475-0071 |
| language | 英語 |
| File Version | publisher |
| NAID | 120002307676 |
| JaLCDOI | 10.18926/15510 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_25_2_39.pdf |
| Author | Nsunge Felix Chintu| Tomita, Eiji| Hamamoto, Yoshisuke| |
| Abstract | Velocity distributions and related parameters of transient and steady, turbulent air jets issuing under atmospheric conditions at Mach 0.14, 0.33 and 0.5 have been predicted using Navier-Stokes(N-S) equations for compressible flow and incompressible flow independently with the k-ε model. The closeness and consistence of the results predicted by the N-S equations for compressible and incompressible flows as well as with relevant measurement or similar prediction show that the incompressible flow assumption for at least some subsonic gas jets issuing at velocities higher than Mach 0.3, the general limit for incompressible fluid flow, can be reasonably accurate particularly in the main fully developed flow region. This suggests that the divergence term in source terms of the momentum, turbulence energy and its dissipation rate equations have negligible effects for some seemingly compressible high speed, subsonic free gas jets. The computation time is reduced by at least 18 % when incompressible flow assumption is used. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1991-03-28 |
| Volume | volume25 |
| Issue | issue2 |
| Start Page | 39 |
| End Page | 54 |
| ISSN | 0475-0071 |
| language | 英語 |
| File Version | publisher |
| NAID | 120002307456 |
| JaLCDOI | 10.18926/15511 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_25_2_55.pdf |
| Author | Ohkura Akira| Kameyama, Yoshimasa| Sayama, Hayatoshi| Suzuki, Kazuhiko| Fukumoto Shuichi| |
| Abstract | AHP can handle decision-making problems involving several criteria when some of these are difficult or impossible to compare other than numerically. When a small group of decision makers settle the multi-criteria problem by AHP, the members of group could not often reach an agreement with hierarchic structure involving objectives, criteria, sub-criteria and alternatives because they have different positions, interests, and opinions. Further, the members have different importances for criteria and sub-criteria, and have dissimilar preferences for alternatives. In this article, we reveal the troubleness of AHP in case of being used by a small group of decision makers. Moreover, we proposed a procedure of AHP which the members of group could easily agree with the structure of problem and the weights of criteria etc. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1991-03-28 |
| Volume | volume25 |
| Issue | issue2 |
| Start Page | 55 |
| End Page | 67 |
| ISSN | 0475-0071 |
| language | 英語 |
| File Version | publisher |
| NAID | 120002307741 |
| JaLCDOI | 10.18926/15438 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_28_1_61.pdf |
| Author | Takeshita, Yuji| Kohno, Iichiro| |
| Abstract | Knowledge of the unsaturated soil hydraulic properties is essential requirement for prediction of seepage flow and contaminant transport through the vadose zone. Unfortunately, these parameters are usually time consuming and expensive to measure in the field and laboratory. At the present condition, there are few data accumulation for Japanese soils. In this paper, van Genuchten's closed-form expressions are described to estimate unsaturated soil hydraulic properties. To evaluate the adequacy of these expressions, comparisons are performed between observed and calculated unsaturated hydraulic properties for typical Japanese soils. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1993-11-30 |
| Volume | volume28 |
| Issue | issue1 |
| Start Page | 61 |
| End Page | 69 |
| ISSN | 0475-0071 |
| language | 英語 |
| File Version | publisher |
| NAID | 120002307801 |
| 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 |
| 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 | 10.18926/15498 |
|---|---|
| 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 | 10.18926/14134 |
|---|---|
| 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 | 10.18926/15466 |
|---|---|
| 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 | 10.18926/15397 |
|---|---|
| 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 | 10.18926/15448 |
|---|---|
| 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 | 10.18926/15453 |
|---|---|
| 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 | 10.18926/15489 |
|---|---|
| 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 | 10.18926/15505 |
|---|---|
| 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 | 10.18926/19588 |
|---|---|
| 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 | 10.18926/19589 |
|---|---|
| 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 | 10.18926/19648 |
|---|---|
| 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 | 10.18926/15381 |
|---|---|
| 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 | 10.18926/15394 |
|---|---|
| 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 |
