vol.32 (2018)

Bulletin of Research Center for Computing and Multimedia Studies
Vol.32, 2018 ISSN 1882-7694

Melting of Argon and Order Parameter byMolecular Dynamics Simulations
Yoduke Kataoka
Received: March 12, 2018    PDF   Abstract
The melting of argon was studied under the constant pressure and also under the constant volume conditions using molecular dynamics simulations. The range of pressure and the density in the simulations were large. The Lennard-Jones potential function was assumed. The initial configuration was FCC lattice. The number of molecule in the basic cell was 864. The total number of the molecular dynamics simulations was 1e6. The first minimum of the pair correlation function was assigned as order parameter in melting. It was lower than 0.5 in solid and it was larger than 0.5 in liquid state. The pre-melting was observed by the self-diffusion coefficient below the melting point. It was assigned as translational motion of the molecules to another sites in the FCC lattice very close to the melting temperature.
Melting Curve of Argon by Constant Temperature Molecular Dynamics Simulations
Yoduke Kataoka
Received: March 13, 2018    PDF   Abstract
Melting curve of argon was calculated by constant temperature molecular dynamics simulations. Lennard-Jones potential function was assumed. The initial configuration was consisted with solid part and liquid part. By this initial configuration, the total molecular dynamics length 1e6 steps was enough to obtain the thermodynamic equilibrium state. The melting point was obtained as solid-liquid co-existent state. The total number of molecules on the basic cell was 2592. The shape of the basic cell was rectangular parallelepiped. The cut-off distance was the half of the short cell length. The melting curve was consistent with the result by free energy calculations. The surface tension was also calculated.
Stability of FCC Structure in the Charged Colloidal Dispersion by Molecular Dynamics Simulations
Yoduke Kataoka
Received: March 13, 2018    PDF   Abstract
The stability of the FCC structure was compared with that of the liquid structure in the charged colloidal dispersion by molecular dynamics simulations. The effective potential of Sogami-Ise theory was assumed. The total number of molecules in the basic cell was 2592. The shape of the basic cell was rectangular parallelepiped. The cut-off distance was the half of the short cell length. Two types of the initial configuration were assumed. Solid-liquid-solid structure was the first one. The second one was liquid-solid-liquid structure. The equilibrium structure did not depend on the initial structure. In the case of the low volume fraction (3%), the FCC structure was more stable than the liquid structure for a typical charge distribution at room temperature. The melting point was estimated as about 880K.
Quantitative Study on Wave Propagation Analysis of the Ground by Advection Method
Keisuke Nakamura, Nagayuki Yoshida
Received: March 15, 2018    PDF   Abstract
Recently, the dynamic behavior for the ground has been studied actively from the view point of the waves. The finite element method (FEM) is known as effective and flexible method in this problem. If the FEM is applied to the wave propagation problem of infinite or semi-infinite elastic body, some numerical procedure is needed for the radiated waves not to reflect at the boundary of the analytical region. The advection equation can decompose the waves of the wave field into the out-going waves and in-coming waves. This study newly develops the non-reflected open boundary procedure of the FEM region based on this characteristic of the advection equation, which is numerically evaluated by the upwind difference method at each time step to perform the wave analysis in time domain.
Behavior of Tip Leakage Flow in Ultra-highly Loaded Axial Turbine Linear Cascade -Influence of Tip Clearance Size-
Hoshio Tsujita, Masanao Kaneko
Received: March 16, 2018    PDF   Abstract
In this study, the computations were performed for the flows in an ultra-highly loaded turbine cascade (UHLTC) with high turning angle of 160 degrees in order to clarify the effects of the tip clearance size on the behavior of tip leakage flow and the associated loss generation. The computed results clarified that the loss caused by the tip leakage vortex was higher than those by the horseshoe vortex and the passage vortex. The increase of tip clearance size enhanced the separation of the leakage vortex from the blade suction surface, and consequently decreased the expansion ratio by the decrease of the cascade outlet flow angle.
Numerical Analysis of Flow in Transonic Axial Compressor -Influence of Turbulence Model-
Masanao Kaneko, Hoshio Tsujita
Received: March 16, 2018    PDF   Abstract
In this study, in order to obtain the knowledge to select a turbulence model which is suitable for a computation of a flow in a transonic compressor with the shock wave formation, the flows in an axial compressor (NASA Rotor 37) under the transonic condition were analyzed numerically by alternatively using the Spalart-Allmaras and the SST k-ω turbulence models. The computed results clarified that the SST k-ω turbulence model more accurately captures the flow phenomena such as the interactions of the shock wave with the boundary layer on the blade surface and the tip leakage vortex.
Research Report on Canvas -Potential for Japanese version NGDLE-
Yuji Tokiwa
Received: March 17, 2018    PDF   Abstract
Canvas, which is one of Learning Management Systems for higher education and K-12, got 77% of all new implementations of primary LMS solutions in US and Canadian higher education for the half year January – June 2016. Canvas is developed by US LMS vender – Instructure to take advantages of cloud and smartphone. So far, a market share in Japan remains low, however it will potentially grow in a future. Through an activity of IMS Japan Society, a relation with Instructure was build and an information on Canvas is accumulated. This paper describes the answer for three research questions. (1) Availability in Japanese universities (2) Potential for Japanese version NGDLE (3) Availability as a research environment for learning support systems.
A Study on Identification Method for Basic Dynamic Characteristics of the Buildings
Yuto Kawai, Kazuhiro Suezaki, Nagayuki Yoshida
Received: March 20, 2018    PDF   Abstract
The structural model should be constructed with high accuracy for exactly redesigning the earthquake resistance ability of old buildings. For this, the procedures for identifying the basic characteristic of the building such as natural frequencies and damping factors are intensively required nowadays. This could be done by measuring the vibration of buildings caused by microtremors of the ground and identifying the vibrational characteristics of buildings. In this study it is investigated whether these dynamic characteristics could be extracted from observed data on small vibration by using MOESP method that is the basic method in subspace identification methods.
Substituent Effects on the Gas-Phase Stabilities of Phenyl Cations
Kazuhide Nakata, Mizue Fujio
Received: October 30, 2017    PDF   Abstract
Substituent effects on the gas-phase stabilities of phenyl cations were computationally determined and analyzed by Yukawa-Tsuno equation to give the ρ value of –22.73 and the r+ value of –0.20 with relatively inferior correlation. Phenyl cations possessing para –R groups show the envelope conformation of the benzene skeleton, which allows NBO interactions between the cationic p-orbital and the benzene-π-electron system. Such the orbital interactions caused the through-resonance effect in the cation. These facts conclude that phenyl cation cannot become an ideal σ0-reference system.