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JaLCDOI 10.18926/17829
フルテキストURL Mem_Fac_Eng_OU_43_16.pdf
著者 Kurose Tomoyuki| 鶴田 健二| 東辻 千枝子| 東辻 浩夫|
抄録 The finite-difference time-domain (FDTD) method has been applied to the calculation of the phonon band structure of two-dimensional (2D) phononic crystals, consisting of metal cylinders placed periodically in liquid. By comparing several combinations of materials for metal cylinder and liquid, we analyze the dependence of the band structures on sound speed and density of liquid media. Moreover, the negative refraction of the acoustic waves is observed at the interfaces between phononic crystal slab and the liquid. We find that an acoustic“lens effect”with the slab appears due to the negative refractions. The relationship between the focal intensity in the lens effect and the band structure is discussed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 16
終了ページ 21
ISSN 1349-6115
言語 英語
論文のバージョン publisher
NAID 120002308928
JaLCDOI 10.18926/17826
フルテキストURL Mem_Fac_Eng_OU_43_8.pdf
著者 Umeda Ryosuke| 東辻 千枝子| 鶴田 健二| 東辻 浩夫|
抄録 Metamaterial which has negative permittivity and permeability is investigated via computer simulations. Effects of the nanostructure on dielectric and magnetic properties of the material are taken into account by introducing the Drude-Lorentz model in the materials dispersion. We include multi-band process in the dielectric response in order to reproduce accurately experimental values of bulk Au thin film. Size effect on the dispersion is examined by comparing the model with that of a noble metal particle. Based on the dispersion model constructed, we analyze the electromagnetic response of nanostructured metamaterials to evanescent waves at microwave and optical frequencies via finite-difference time-domain simulatioins on parallel computer. A re- focusing and an amplification of the evanescent waves propagating through a metamaterial, consisting of metal slab/vacuum stacking, is demonstrated for the frequencies of 30GHz and 744THz.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 8
終了ページ 15
ISSN 1349-6115
言語 英語
論文のバージョン publisher
NAID 120002308833
JaLCDOI 10.18926/15837
フルテキストURL Mem_Sch_Eng_OU_21_2_1.pdf
著者 Takemoto Yoshito| Hida Moritaka|
抄録 We investigated the effects of resolved interstitial oxygen or nitrogen atoms and of quenched-in strain on the hardening of the single crystals grown from molten Ti-14 and 20wt pct Mo alloys. The aging treatment at 623K in atmosphere much more increased in the hardness of specimen surface than that in argon atmosphere. The quenched-in compressive stress enhanced age hardening due to omega formation. We surveyed in detail the hardness changes toward the center of plate-shaped single crystal.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1987-03-05
21巻
2号
開始ページ 1
終了ページ 7
ISSN 0475-0071
言語 日本語
論文のバージョン publisher
NAID 120002307640
JaLCDOI 10.18926/15511
フルテキストURL Mem_Fac_Eng_OU_25_2_55.pdf
著者 Ohkura Akira| 亀山 嘉正| 佐山 隼敏| 鈴木 和彦| Fukumoto Shuichi|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1991-03-28
25巻
2号
開始ページ 55
終了ページ 67
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307741
JaLCDOI 10.18926/15510
フルテキストURL Mem_Fac_Eng_OU_25_2_39.pdf
著者 Nsunge Felix Chintu| 冨田 栄二| 浜本 嘉輔|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1991-03-28
25巻
2号
開始ページ 39
終了ページ 54
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307456
JaLCDOI 10.18926/15508
フルテキストURL Mem_Fac_Eng_OU_25_2_25.pdf
著者 Nsunge Felix Chintu| 冨田 栄二| 浜本 嘉輔|
抄録 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).
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1991-03-28
25巻
2号
開始ページ 25
終了ページ 38
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307676
JaLCDOI 10.18926/15500
フルテキストURL Mem_Fac_Eng_OU_25_2_1.pdf
著者 Okada, Hiroyuki| 飛田 守孝| 榊原 精| 竹元 嘉利|
抄録 Tensile strength and elongation of cast magnesium reinforced with titanium fiber were measured by tensile test. The pull-out test of a titanium rod partially embedded in a magnesium matrix was performed to evaluate interfacial bonding strength between magnesium and titanium. It was found that when the fiber volume fraction was changed from 1% to 14%, the tensile strength was improved with increase of volume fraction, while the improvement of elongation tended to be restrained beyond the volume fraction of 10%. The interfacial strength was revealed to be strong, and this was substantiated by the scanning electron microscopy showing an excellent wettability between the titanium fiber and the magnesium matrix.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1991-03-28
25巻
2号
開始ページ 1
終了ページ 8
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307559
JaLCDOI 10.18926/15489
フルテキストURL Mem_Fac_Eng_OU_24_2_1.pdf
著者 Umemoto, Masayuki| 竹元 嘉利| 榊原 精| 飛田 守孝|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1990-03-29
24巻
2号
開始ページ 1
終了ページ 9
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307765
JaLCDOI 10.18926/15453
フルテキストURL Mem_Fac_Eng_OU_28_2_13.pdf
著者 Kusumoto, Hisao| 飛田 守孝| 榊原 精| Nishida, Norihide| 竹元 嘉利| 山田 益男|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1994-03-15
28巻
2号
開始ページ 13
終了ページ 20
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307150
JaLCDOI 10.18926/15448
フルテキストURL Mem_Fac_Eng_OU_28_2_1.pdf
著者 竹元 嘉利| 榊原 精| 飛田 守孝|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1994-03-15
28巻
2号
開始ページ 1
終了ページ 7
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307644
JaLCDOI 10.18926/15436
フルテキストURL Mem_Fac_Eng_OU_26_2_69.pdf
著者 Fujii, Tatsuo| Sakata Naoki| Nanba, Tokuro| Osaka, Akiyoshi| Miura, Yoshinari| Takada, Jun|
抄録 (001)-oriented Ti(2)O(3) films were epitaxially grown on a(001)-face of sapphire single-crystalline substrate by an activated reactive evaporation method. The formation ranges of stoichiometric and nonstoichiometric Ti(2)O(3) films were determined as a function of the substrate temperature (Ts), the oxygen pressure (Po(2)) and the deposition rate. Stoichiometric Ti(2)O(3) films were grown at Ts≧673K under Po(2)≧1.0×10(-4)Torr, which showed the metal-insulator transition with a sharp change in electrical resistivity from 3.5×10(-2) to 2.6×10(-3)Ωcm at 361K. Nonstoichiometric films prepared under less oxidized conditions did not exhibit the transition. The nonstoichiometry of the Ti(2)O(3)films was discussed in terms of excess Ti ions.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1992-03-28
26巻
2号
開始ページ 69
終了ページ 75
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307639
JaLCDOI 10.18926/15414
フルテキストURL Mem_Fac_Eng_OU_26_1_27.pdf
著者 冨田 栄二| Nsunge Felix Chintu| 浜本 嘉輔|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1991-11-30
26巻
1号
開始ページ 27
終了ページ 41
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307648
JaLCDOI 10.18926/15397
フルテキストURL Mem_Fac_Eng_OU_30_2_1.pdf
著者 竹元 嘉利| 飛田 守孝| 榊原 精|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1996-03-29
30巻
2号
開始ページ 1
終了ページ 7
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307225
JaLCDOI 10.18926/15391
フルテキストURL Mem_Fac_Eng_OU_27_1_33.pdf
著者 島田 行恭| 鈴木 和彦| 佐山 隼敏|
抄録 Neural nets have recently become the focus of much attention, largely because of their wide range of complex and nonlinear problems. This paper presents a new integrated approach using neural networks for diagnosing process failures. The fault propagation in process is modeled by causal relationships from the fault tree and its minimal cut sets. The measurement patterns required for training and testing the neural network were obtained from fault propagation model. The network is able to diagnose even in the presence of malfunction of certain sensors. We demonstrate via a nitric acid cooler process how the neural network can learn and successfully diagnose the faults.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1992-11-25
27巻
1号
開始ページ 33
終了ページ 44
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307902
JaLCDOI 10.18926/15380
フルテキストURL Mem_Fac_Eng_OU_35_197.pdf
著者 Nogami, Yasuyuki| Morikawa, Yoshitaka|
抄録 Modern communication engineerings, such as elliptic curve cryptographies, often requires algebra on finite extension field defined by modulus arithmetic with an irreducible polynomial. This paper provides a new method to detemine the minimal (irreducible) polynomial of a given proper element in finite extension field. In the conventional determination method, as we have to solve the simultaneous equations, the computation is very involved. In this paper, the well known "trace" is extended to higher degree traces. Using the new traces, we yield the coefficient formula of the desired minimal polynomial. The new method becomes very simple without solving the simultaneous equations, and about twice faster than the conventional method in computation speed.
キーワード finite field minimal polynomial irreducible polynomial higher degree trace trace cryptography
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2001-03-27
35巻
1-2号
開始ページ 197
終了ページ 205
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307992
JaLCDOI 10.18926/15361
フルテキストURL Mem_Fac_Eng_OU_35_77.pdf
著者 Kishimoto Tokunari| 東辻 千枝子| 鶴田 健二| 東辻 浩夫|
抄録 In order to perform the large-scale molecular dynamics simulation of the Yukawa system, a mathematical expression for molecular dynamics using the fast multipole method is described. The model simulations are also performed to test the performance of our implementation of the FMM.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2001-03-27
35巻
1-2号
開始ページ 77
終了ページ 95
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307940
JaLCDOI 10.18926/15360
フルテキストURL Mem_Fac_Eng_OU_34_27.pdf
著者 Wei, He| 古賀 隆治| 五百旗頭 健吾| 和田 修己| 豊田 啓孝|
抄録 In spring of 1998, Asian dust was observed with a Mie LIDAR in Okayama University, which can measure depolarization ratio. Three events of intense Asian dust were occurred in the period and medially detailed structure of atmosphere was found after examining records. Asian dust was distinguished from water droplets and the possibility to study three dimensional dynamic structure of atmosphere were demonstrated.
キーワード Mie lidar Asian dust (KOSA) depolarization ratio backscattering ratio range normalized
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2000-03-27
34巻
1-2号
開始ページ 27
終了ページ 37
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307539
JaLCDOI 10.18926/15359
フルテキストURL Mem_Fac_Eng_OU_34_19.pdf
著者 Okada, Akira| Uno, Yoshiyuki| Okajima, Isao|
抄録 In EDM, the machining characteristics greatly depend on the energy distribution. Therefore, it is very important to clarify the energy distribution for understanding various phenomena in EDM. In this paper, the energy distribution in EDM with graphite electrode is investigated by measuring the temperatures of electrode and workpiece. Experimental analysis shows that the material removal rate depends on energy density while the electrode wear greatly depends on the adhesion of heat resolved carbon from machining fluid, and the energies distributed into electrode and workpiece are almost constant regardless of pulse duration.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2000-03-27
34巻
1-2号
開始ページ 19
終了ページ 26
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307707
JaLCDOI 10.18926/15358
フルテキストURL Mem_Fac_Eng_OU_35_63.pdf
著者 Shinomiya Shigeru| 東辻 千枝子| 鶴田 健二| 東辻 浩夫|
抄録 We present a theoretical study of Si(1-x)Ge(x) alloys based on tight-binding molecular dynamics (TBMD) calculations. First, we introduce a new set of nonorthogonal tight-binding parameters for silicon and germanium based on the previous work by Menon and Subbaswamy [Phys. Rev. B 55, 9231 (1997); J. Phys: Condens. Matter 10, 10991 (1998)]. We then apply the method to structural analyses of Si(1-x)Ge(x) alloys. The equilibrium volume and atomic structure for a given x are obtained by the TBMD method. We also calculate the bulk modulus B, elastic constants C(11), C(12) and C(44) as a function of x. The results show that the moduli vary monotonically, but nonlinearly, between the values of Si crystal and Ge crystal. The validity of the results is also discussed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2001-03-27
35巻
1-2号
開始ページ 63
終了ページ 75
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307673
JaLCDOI 10.18926/15354
フルテキストURL Mem_Fac_Eng_OU_34_1.pdf
著者 Song Baoyin| 稲葉 英男| 堀部 明彦| Takahashi Takashi|
抄録 The experiment for investigating the falling snow melting characteristics of warm water flowing along sheet channels spread on a roof was performed in Tookamachi city, Nigata prefecture from February 6 to February 7, 1995. The sheet surface temperatures at 11 positions in 3 channels were measured. A physical model for a gas-water-snow system was constructed to compare the predicted results with the measured ones. A fully spread uniform water film in the sheet channel was observed in the experiments. The experimental results elucidated that it was feasible to use warm water flowing along sheet channels for melting falling snow on roofs. The temperature drop in the sheet channel mainly depended on the snowfall intensity, atmospheric temperature and wind speed. Under the influence of the roof edge, the temperature drop in the channel next to the side edge was much larger than that in middle channels. A water-snow two phase flow or a snow covered frozen water was experienced temporarily in the lower reaches of the water flowing channel. These suggest that a larger water flow rate is needed for the channel next to the roof edge, and a higher inlet temperature or a greater water flow rate is required for a severe weather condition. There was reasonably good agreement between the measured and predicted water temperatures.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2000-03-27
34巻
1-2号
開始ページ 1
終了ページ 12
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307686