| JaLCDOI | 10.18926/46982 |
|---|---|
| FullText URL | mfe_37_2_073_087.pdf |
| Author | Nogami, Yasuyuki| Morikawa, Yoshitaka| |
| Abstract | Public key cryptosystem has many uses, such as to sign digitally, to realize electronic commerce. Especially, RSA public key cryptosystem has been the most widely used, but its key for ensuring sufficient security reaches about 2000 bits long. On the other hand, elliptic curve cryptosystem(ECC) has the same security level with about 7-fold smaller length key. Accordingly, ECC has been received much attention and implemented on various processors even with scarce computation resources. In this paper, we deal with an elliptic curve which is defined over extension field F(p2c) and has a prime order, where p is the characteristic and c is a non negative integer. In order to realize a fast software implementation of ECC adopting such an elliptic curve, a fast implementation method of definition field F(p2c) especially F(p8) is proposed by using a technique called successive extension. First, five fast implementation methods of base field F(p2) are introduced. In each base field implementation, calculation costs of F(p2)-arithmetic operations are evaluated by counting the numbers of F(p)-arithmetic operations. Next, a successive extension method which adopts a polynomial basis and a binomial as the modular polynomial is proposed with comparing to a conventional method. Finally, we choose two prime numbers as the characteristic, and consider several implementations for definition field F(p8) by using five base fields and two successive extension methods. Then, one of these implementations is especially selected and implemented on Toshiba 32-bit micro controller TMP94C251(20MHz) by using C language. By evaluating calculation times with comparing to previous works, we conclude that proposed method can achieve a fast implementation of ECC with a prime order. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2003-03 |
| Volume | volume37 |
| Issue | issue2 |
| Start Page | 73 |
| End Page | 87 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80015999992 |
| JaLCDOI | 10.18926/46983 |
|---|---|
| FullText URL | mfe_37_2_089_097.pdf |
| Author | Iokibe, Kengo| Toyota, Yoshitaka| Wada, Osami| Koga, Ryuji| |
| Abstract | Aerosol extinction coefficients of clouds and dust were continuously measured in the year of 2002 with a polarized Mie-scattering lidar controlled by an automatic and remotely operating system utilizing internet services. Measured cloud extinctions were greater than 1.0 km(-1) below the altitude 6 km, 0.17 - 1.0 km(-1) between 6 and 10 km, and 0.091 - 0.3 km(-1) beyond 10km. Extinction of dust were 0.10 and 0.20 km(-1) for Asian dust and 0.057 km(-1) for urban dust. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2003-03 |
| Volume | volume37 |
| Issue | issue2 |
| Start Page | 89 |
| End Page | 97 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003457336 |
| Author | Faculty of Engineering, Okayama University| |
|---|---|
| Published Date | 2003-03 |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Volume | volume37 |
| Issue | issue2 |
| Content Type | Others |
| Author | Faculty of Engineering, Okayama University| |
|---|---|
| Published Date | 2001-12 |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Volume | volume36 |
| Issue | issue1 |
| Content Type | Others |
| JaLCDOI | 10.18926/46995 |
|---|---|
| FullText URL | mfe_36_1_001_006.pdf |
| Author | Kondou, Ryouji| Abe, Takeji| Tada, Naoya| Shimizu, Ichiro| |
| Abstract | Change in crystal orientation and strain of individual grains during tensile plastic deformation are studied to clarify on the microscopic deformation behavior of polycrystalline copper. The orientation of grain is measured by electron backscatter diffraction (EBSD) technique in the scanning electron microscope. The principal strain of grain is also measured by obtaining the approximated ellipse of strain distribution. The deformation of grains dependent on their initial orientation and the rotation of the principal strain during uniaxial tension are clarified. |
| Keywords | Polycrystalline Copper Plastic Deformation SEM EBSD Method Grain Orientation Crystal Orientation Map |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 6 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497021 |
| JaLCDOI | 10.18926/46996 |
|---|---|
| FullText URL | mfe_36_1_007_016.pdf |
| Author | Li, Yan| Abe, Takeji| Tada, Naoya| Kanazawa, Masanori| |
| Abstract | The change in the surface morphology of polycrystalline titanium during tensile plastic deformation is studied, using the scanning probe microscope as well as the laser scanning microscope. The observation shows that the slip occurs mainly near grain boundary at the strain range of ε < 0.05. The slip develops with the applied strain, and the slip on the second slip system or the crossing of slip lines appear. The surface roughness increases linearly with the applied strain. The height difference between the grain boundary area and the inner grain area also increases with the applied strain, though the increase rate becomes low after the applied strain of about 0.3. The nano-scale height difference of the surface step of slip lines increases with the applied strain, though it remains almost constant after the applied strain of 0.4. The averaged surface roughness measured with the scanning probe microscope is in good agreement with that measured with the laser scanning microscope. |
| Keywords | Plasticity Polycrystalline Titanium Tensile Deformation Surface Morphology Slip Twin Probe Scanning Microscope Laser Scanning Microscope |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 7 |
| End Page | 16 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80012831215 |
| JaLCDOI | 10.18926/46997 |
|---|---|
| FullText URL | mfe_36_1_017_028.pdf |
| Author | Endo, Shinichiro| Konishi, Masami| |
| Abstract | Small Scale Hydroelectric Power Generation is made using the water drop caused by the gradient difference between that of the river and that of the penstock. The water flow in this system apt to vary with time. Especially, at the time of the flood or that of the dry, the flow in the water stream varies largely. To realize the stable generation, it is necessary to maintain the water level in the head tank located in the mid way in the stream channel at a constant level. In this paper, variation of water level is forecasted using two-tank model for the penstock and the head tank and the water level control algorithm is proposed by deadbeat control. The effectiveness of the algorithm is evaluated beforehand using the simulation program of the water environment for the hydroelectric generation system. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 17 |
| End Page | 28 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497023 |
| JaLCDOI | 10.18926/46998 |
|---|---|
| FullText URL | mfe_36_1_029_039.pdf |
| Author | Imai, Jun| Wada, Kiyoshi| |
| Abstract | A procedure for control-oriented modeling is proposed for large flexible structures with unknown modal parameters. Techniques on quantification of errors in modal truncated nominal models are developed for the case where a finite number of upper and lower bounds of the unknown modal parameters are given. A feasible set of systems matching the conditions is introduced, and then error bounds covering the feasible set are established in the frequency domain. The bounds are easily checked using linear programming for any user-specified frequency. The feasibility of the proposed scheme is illustrated by numerical study on an ideal flexible beam example. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 29 |
| End Page | 39 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80012887118 |
| JaLCDOI | 10.18926/46999 |
|---|---|
| FullText URL | mfe_36_1_041_049.pdf |
| Author | Totsuji, Hiroo| Kishimoto, Tokunari| Totsuji, Chieko| Tsuruta, Kenji| |
| Abstract | The ground state of spherical clusters of charged particles of one species confined by the three-dimensional parabolic potential is investigated by molecular dynamics simulations with the system size from N = 5000 to N = 1.2 × 10(5) . The cohesive energy per particle is compared between the shell-structured clusters and spherical finite bcc lattices with relaxed surfaces, the former and the latter being the ground states for small systems and for the large enough systems, respectively. It is shown that, when N > N(c)(N(c) > N), finite bcc lattices with relaxed surfaces (the shell structures) have stronger cohesion than the shell structures (finite bcc lattices with relaxed surfaces) and the critical value of the transition N(c) is estimated to be 10(4) < N(c) < 1.4 × 10(4) . The nucleation of the bcc lattice in the shell-structured cluster of 2 × 10(4) ions is observed. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 41 |
| End Page | 49 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80015112663 |
| JaLCDOI | 10.18926/47001 |
|---|---|
| FullText URL | mfe_36_1_059_077.pdf |
| Author | Kanatani, Kenichi| |
| Abstract | Contrasting "geometric fitting", for which the noise level is taken as the asymptotic variable, with "statistical inference", for which the number of observations is taken as the asymptotic variable, we give a new definition of the "geometric AIC" and the "geometric MDL" as the counterparts of Akaike's AIC and Rissanen's MDL. We discuss various theoretical and practical problems that emerge from our analysis. Finally, we show, doing experiments using synthetic and real images, that the geometric MDL does not necessarily outperform the geometric AIC and that the two criteria have very different characteristics. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 59 |
| End Page | 77 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80012855281 |
| JaLCDOI | 10.18926/47002 |
|---|---|
| FullText URL | mfe_36_1_079_090.pdf |
| Author | Kanatani, Kenichi| |
| Abstract | We first present an improvement of Kanatani's subspace separation [8] for motion segmentation by newly introducing the affine space constraint. We point out that this improvement does not always fare well due to the effective noise it introduces. In order to judge which solution to adopt if different segmentations are obtained, we present two criteria: one is the standard F test; the other is model selection using the geometric AIC of Kanatani [7] and the geometric MDL of Matsunaga and Kanatani [13]. We test these criteria doing real image experiments. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 79 |
| End Page | 90 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497028 |
| JaLCDOI | 10.18926/47004 |
|---|---|
| FullText URL | mfe_36_1_107_116.pdf |
| Author | Kanatani, Kenichi| Ohta, Naoya| |
| Abstract | We present a new method for automatically detecting circular objects in images: we detect an osculating circle to an elliptic arc using a Hough transform, iteratively deforming it into an ellipse, removing outlier pixels, and searching for a separate edge. The voting space is restricted to one and two dimensions for efficiency, and special weighting schemes are introduced to enhance the accuracy. We demonstrate the effectiveness of our method using real images. Finally, we apply our method to the calibration of a turntable for 3-D object shape reconstruction. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 107 |
| End Page | 116 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80012855284 |
| JaLCDOI | 10.18926/47005 |
|---|---|
| FullText URL | mfe_36_1_117_121.pdf |
| Author | Shirosaki, Yuki| Tsuru, Kanji| Hayakawa, Satoshi| Osaka, Akiyoshi| Takashima, Seisuke| |
| Abstract | γ-Methacryloxypropyltrimethoxysilane (γ-MPS) was grafted to silicone due to emulsion polymerization to induce Si-OH groups, in order to provide silicone with bioactivity spontaneous deposition of apatite in body fluid and to improve cytocompatibility. Apatite deposited on the grafted silicone within 7 days of soaking in 1.5 times as concentrated as the Kokubo solution. Osteoblastic cells (MC3T3-E1) were cultured on the specimens up to 7 days. After 5 days of culture, the number of MC3T3-E1 cells on the grafted specimen was much greater than that on the original specimen. These results indicated that the biocompatibility of silicone elastomer was improved by the grafting γ-MPS. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2001-12 |
| Volume | volume36 |
| Issue | issue1 |
| Start Page | 117 |
| End Page | 121 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497031 |
| Author | Faculty of Engineering, Okayama University| |
|---|---|
| Published Date | 2001-12 |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Volume | volume36 |
| Issue | issue1 |
| Content Type | Others |
| Author | Faculty of Engineering, Okayama University| |
|---|---|
| Published Date | 2002-03 |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Volume | volume36 |
| Issue | issue2 |
| Content Type | Others |
| JaLCDOI | 10.18926/47021 |
|---|---|
| FullText URL | mfe_36_2_001_006.pdf |
| Author | Sakakibara, Akira| Kanadani, Teruto| Tashiro, Tsutomu| Yoshioka, Kazumi| |
| Abstract | The effect of heat-treatment conditions on occurrence of serration in Al-Zn alloys was investigated. Specimens were aged for various times up to 2.6Ms at 293K or 273K after quenching from various temperatures (T(Q)), 473K to 853K, and tensile-tested at room temperature. Serration occurred more easily according as T(Q) became lower and the aging time became shorter: in the case that T(Q)=473K serration was observed even after aging for 2.6Ms, while in the case that T(Q)=773K serration did not occur irrespective of aging conditions. Serration was also recognized when the specimens were furnace-cooled from 773K to room temperature. These results together with those obtained by the electrical resistometry suggest that the serration in the low'concentrated Al-Zn alloy is caused by the formation of small GP zones whose Guinier radius is less than 1nm or some sort of solute clusters. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2002-03 |
| Volume | volume36 |
| Issue | issue2 |
| Start Page | 1 |
| End Page | 6 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80015497758 |
| JaLCDOI | 10.18926/47022 |
|---|---|
| FullText URL | mfe_36_2_007_013.pdf |
| Author | Abe, Takeji| Nagao, Makoto| Ohta, Tomoyuki| Nagayama, Noriyuki| |
| Abstract | It is important to study the microscopic deformation behavior of inhomogeneous material, for most engineering materials are inhomogeneous. The aim of the present study is to clarify by numerical analysis some features of microscopic plastic strain distributions, the mean flow stress and the material factors affecting on it. The rigid-plastic solution is important not only for plastic deformation problems with large strain, but also for creep deformation problems through the plastic analogy in the creep analysis. The effects of material parameter and loading conditions on the deformation behavior of the material are examined and discussed based on the result of calculation. The effects of the aspect ratio of the inhomogeneous regions on the deformation mode are studied. The patterns of the strain concentration and the averaged flow stress of the inhomogeneous material are also discussed. The results of rigid-plastic material are compared with those of the elastic material. |
| Keywords | Plasticity Deformation Inhomogeneous Material Strain Concentration Coefficient Rigid-Plastic FEM |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2002-03 |
| Volume | volume36 |
| Issue | issue2 |
| Start Page | 7 |
| End Page | 13 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497044 |
| JaLCDOI | 10.18926/47023 |
|---|---|
| FullText URL | mfe_36_2_015_042.pdf |
| Author | Ohtani, Ryuji| Konishi, Masami| Imai, Jun| Nishi, Tatsushi| |
| Abstract | In this paper, we studied a planning and scheduling of production system considering demand changes. In the proposed system, planning part determines lot-size and amount of jobs in production. On the other hand, scheduling part determines the production sequence of jobs. In order to treat with the demand changes, both planning and scheduling should work well simultaneously. In the proposed system, preset and real time production control system is newly constructed from the view point of adaptive control. In the system, production planning is modified when the difference between production amount and demand becomes large. Moreover, production schedule is regenerated when the determined schedule is deviated from the prospected one. The scheduling system is characterized as the autonomous decentralized optimization system where each job works as agent and agent searches its appropriate starting time of processing. The effectiveness of the proposed system is confirmed by numerical examples. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2002-03 |
| Volume | volume36 |
| Issue | issue2 |
| Start Page | 15 |
| End Page | 42 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 80015471209 |
| JaLCDOI | 10.18926/47024 |
|---|---|
| FullText URL | mfe_36_2_043_049.pdf |
| Author | Vaillancourt, Chico| |
| Abstract | In this case study, I will analyse and discuss the results of a survey concerning motivation towards learning a second language conducted in four Canadian schools. This section, part one of the study, was conducted in the Sudbury Region of Ontario, Canada. This region of the world was chosen because bilingualism is quite common there and a large portion of the community has learned a second language. Part two will be conducted in the winter of 2002, in Denmark, a European country that neighbours many countries with different mother tongues, I hope to conclude this case study with part three in the summer of 2002, in Japan, a monolingual island nation. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2002-03 |
| Volume | volume36 |
| Issue | issue2 |
| Start Page | 43 |
| End Page | 49 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120003497045 |
| JaLCDOI | 10.18926/19654 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_33_2_9.pdf |
| Author | Yamamoto, Kyoji| |
| Abstract | The molecular dynamics study is applied for interaction of the gas molecule with the solid wall to analyse the flow of a rarefied gas between two wall. The wall consisting of Pt molecules is considered to be in a state of physical adsorbates. Two problems are considered : one is the flow problem and the other is the temperature problem. It is found that the tangential momentum accommodation coefficient is about 0.8 when the relative speed ratio of the two walls is unity, while it decreases with increasing Knudsen number when the relative wall speed ratio is 5.0. It shown that the temperature accommodation coefficient is about 0.85 at 300K wall, 0.75 at 450K wall, and 0.69 at 600K wall. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 1999-04-27 |
| Volume | volume33 |
| Issue | issue2 |
| Start Page | 9 |
| End Page | 17 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002309121 |
