Bulletin of Research Center for Computing and Multimedia Studies, Hosei University
Online ISSN : 1882-7594
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  • Anna Vardanyan, Norio Takeuchi
    2021 Volume 36 Pages 1-10
    Published: July 08, 2021
    Released: July 22, 2021
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    In the hybrid-type penalty method (HPM), an independent displacement field is assumed for each element, and the continuity of displacement between the elements is approximated using a penalty function. Therefore, the relative displacement of the local coordinate system along the element boundary is required. However, when modeling a shell structure of an arbitrary shape with flat shell elements, the relative displacement between the two elements cannot be easily obtained because the adjacent elements are joined at an angle. In this study, the displacement field represented by the local coordinate system for each element was transformed into a local coordinate system of the adjacent element. We then propose a method for computing the relative displacement from these displacements. From a simple numerical example, we show that a shell structure with an arbitrary shape can be modeled with flat shell elements.
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  • Yosuke Kataoka
    2021 Volume 36 Pages 11-15
    Published: July 08, 2021
    Released: July 22, 2021
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    Vapor-liquid equilibrium in Argon is studied by constant pressure molecular dynamics simulation. The boiling point and the transition of entropy due to vaporization were estimated. Maxwell construction method was adopted. The results were compared with the experimental data.
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  • Yosuke Kataoka
    2021 Volume 36 Pages 16-20
    Published: July 08, 2021
    Released: July 22, 2021
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    The triple point in argon was estimated by molecular dynamics simulation. Constant temperature and constant energy ensemble were used. The triple point was obtained. It was compared with the experimental data and the results of equation of state.
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  • Yosuke Kataoka
    2021 Volume 36 Pages 21-24
    Published: July 08, 2021
    Released: July 22, 2021
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    The fluctuation of potential energy and pressure of argon were studied by molecular dynamics simulation in canonical ensemble. Pressure was written as sum of the ideal gas term and the interaction one. The interaction term fluctuated by a large scale in the condensed phase. The convergence characters were examined as functions of N, where N is the number of molecules in the basic cell.
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  • Qinlin Wang, Yasunari Zempo
    2021 Volume 36 Pages 25-30
    Published: July 08, 2021
    Released: July 22, 2021
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    We have been studying the time-evolution technique in imaginary time. The electronic structure calculated in this technique is valid for the ground state, which is easily confirmed from the completeness of the wavefunction. However, the excited states can be also obtained by Gram-Schmidt orthogonalization technique. We applied this technique to well-known systems such as 1D quantum well, Morse, and 3D harmonic potential systems. The results are in good agreement with their analytical solutions, including the excited states. The purpose of this study is to present the effectiveness of this technique for practical electronic structure calculations. In order to realize it, we will start to apply this to hydrogen and practical small molecule systems.
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  • Hoshio Tsujita, Masanao Kaneko
    2021 Volume 36 Pages 31-36
    Published: July 08, 2021
    Released: July 22, 2021
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    In this study, the compressible turbulent flow in the ultra-highly loaded axial turbine linear cascade (UHLTC) was numerically analyzed by using the commercial CFD code in order to clarify the characteristic vortex flow structure in the cascade passage in detail. The computed results suggested that the passage vortex was not generated because of the rapid and strong separation of the pressure side leg of horseshoe vortex from the endwall. As a result, the effective loss reduction technique for UHLTC was considered to be the leading edge filet which had the ability to reduce the leading edge horseshoe vortex.
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  • Ryota Serizawa, Yuki Takeda, Yukihiro Ishibashi, Hajime Yano, Kazuyosh ...
    2021 Volume 36 Pages 37-41
    Published: July 08, 2021
    Released: July 22, 2021
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    Capturing and analyzing cometary coma dust leads to elucidate the origin of the solar system. JAXA/ISAS is currently developing core technology for sample return of microparticles ejected at a lower velocity after rendezvous with a cometary nucleus. “Carbon Nanotube (CNT) carpets” are an effective capture medium for such a purpose. In this paper, the effect of capture performance in shape designing of the CNT carpets was evaluated using computer simulations. Based on simulation results, design guideline of CNT carpets was proposed to use in comet rendezvous sample return missions.
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  • Haruki Numajiri
    2021 Volume 36 Pages 42-46
    Published: July 08, 2021
    Released: July 22, 2021
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    The study by Numajiri [1] well reproduced the seasonal variation of river runoff by a monthly basin water balance model using a distributed tank model. The search for the optimal parameters is important for the construction of this distributed tank model. However, the method is not easy. When Sugawara [2] invented the tank model, Sugawara gave up the automatic search for the optimum parameters, citing one of the reasons that the computing power of the computer takes time. Numajiri [1] attempted automatic optimization by the conditional brute force attack method using a personal computer with improved performance. The purpose of this study is to improve the efficiency of optimal parameter exploration by using a machine learning library.
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  • Eric Hagley
    2021 Volume 36 Pages 47-53
    Published: July 08, 2021
    Released: July 22, 2021
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    The Japanese government’s ministry of Education, Culture, Sports, Science and Technology rightly promoted the “Concept of Global Human Resource Development” in 2010 and continued to do so in the second basic plan for the Promotion of Education in 2013 and thereafter. Specifically the plans note that “it is important to cultivate global human resources who possess rich linguistic abilities, communication abilities, autonomy, and positivity, and who are able to work actively in various fields with an intercultural understanding spirit.” [1]. The proposed goal is worthy but attaining it is extremely difficult for the majority of Japanese students unless technology is used. This paper states that Virtual Exchange (VE) is the key to ensuring students throughout Japan can interact with students in other cultures, thereby becoming exposed to new ideas where intercultural understanding can develop and the goals, outlined in the second basic plan, can be achieved.
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  • Kohei Nakasaka, Hidechika Karasawa, Ohi Kunishima, Kazuyoshi Arai
    2021 Volume 36 Pages 54-57
    Published: July 08, 2021
    Released: July 22, 2021
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    In this study, in order to investigate the material physical properties that affect the delamination of CFRP, impact analysis was performed by changing four types of physical properties. The tensile strength, interlayer shear strength, and Mode I interlayer fracture toughness and Mode II interlayer fracture toughness were used as four kinds of material physical properties.
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  • Hiroshi Ueda, Hisashi Hatakeyama, Mohammad Nehal Hasnine, Syuichi Naka ...
    2021 Volume 36 Pages 58-63
    Published: July 08, 2021
    Released: July 22, 2021
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    The 2021 Symposium of Research Center for Computing and Multimedia Studies, Hosei University was held online on 11 March 2021. This short article introduces outline of the 2021 symposium.
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  • Kazuhide Nakata
    2021 Volume 36 Pages 64-77
    Published: July 08, 2021
    Released: July 22, 2021
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    Relative gas-phase stabilities (ΔEX) of ring-substituted 2-phenyl-1,3-dehydroadamantane-5,7-diyliums were computationally determined as the energy difference of hydride transfer equilibria between ring-substituted and its parent dications. The generating process of the dications from the corresponding neutral species were divided into two steps: the generation step of the mono-cations from the neutral species and that of the dications from the mono-cations. The ΔEX of these processes were also determined in the same manner. Obtained substituent effects were compared to those of α,α-dimethylbenzyl cations (σ+-reference) and 90˚-fixed α,α-dimethylbenzyl cations (σ0-reference). Statistical analyses revealed negligible through-resonance effects and a wide variety of saturation effects in these electron-deficient systems. The result is in contrast with those of 1-phenylcyclobutane-1,3-diyliums and 1-phenylcyclopentane-1,3-diyliums that show both significant through-resonance and saturation effects. The through-resonance and saturation effects were revealed to be independent of each other to confirm that the three-term extended Yukawa-Tsuno equation,-ΔE=ρ(σ0+r+ΔσR++S+ΔσS+), is intrinsic for substituent-effect analyses in the electron-deficient species.

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  • Hisashi Hatakeyama, Hiroshi Ueda
    2021 Volume 36 Pages 78-81
    Published: July 08, 2021
    Released: July 22, 2021
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    We have developed a tool specializing in audio file distribution to utilize audio contents in online classes at universities. This tool, named “Lectcast,” can be used in conjunction with the learning management system by LTI and supports audio playback on the browser and podcast feed generation. The student questionnaire survey results in the online class using “Lectcast” suggest that audio materials have certain usefulness as a supplement to text-based learning contents.
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