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Mochida, A.,Tominaga, Y.,Murakami, S.,Yoshie, R.,Ishihara, T.,Ooka, R. Techno-Press 2002 Wind and Structures, An International Journal (WAS Vol.5 No.2
Recently, the prediction of wind environment around a building using Computational Fluid Dynamics (CFD) technique comes to be carried out at the practical design stage. However, there have been very few studies which examined the accuracy of CFD prediction of flow around a high-rise building including the velocity distribution at pedestrian level. The working group for CFD prediction of wind environment around building, which consists of researchers from several universities and private companies, was organized in the Architectural Institute of Japan (AIJ) considering such a background. At the first stage of the project, the working group planned to carry out the cross comparison of CFD results of flow around a high rise building by various numerical methods, in order to clarify the major factors which affect prediction accuracy. This paper presents the results of this comparison.
Generation of inflow turbulent boundary layer for LES computation
Kondo, K.,Tsuchiya, M.,Mochida, A.,Murakami, S. Techno-Press 2002 Wind and Structures, An International Journal (WAS Vol.5 No.2
When predicting unsteady flow and pressure fields around a structure in a turbulent boundary layer by Large Eddy Simulation (LES), velocity fluctuations of turbulence (inflow turbulence), which reproduce statistical characteristics of the turbulent boundary layer, must be given at the inflow boundary. However, research has just started on development of a method for generating inflow turbulence that satisfies the prescribed turbulence statistics, and many issues still remain to be resolved. In our previous study, we proposed a method for generating inflow turbulence and confirmed its applicability by LES of an isotropic turbulence. In this study, the generation method was applied to a turbulent boundary layer developed over a flat plate, and the reproducibility of turbulence statistics predicted by LES computation was examined. Statistical characteristics of a turbulent boundary layer developed over a flat plate were investigated by a wind tunnel test for modeling the cross-spectral density matrix for use as targets of inflow turbulence generation for LES computation. Furthermore, we investigated how the degree of correspondence of the cross-spectral density matrix of the generated inflow turbulence with the target cross-spectral density matrix estimated by the wind tunnel test influenced the LES results for the turbulent boundary layer. The results of this study confirmed that the reproduction of cross-spectra of the normal components of the inflow turbulence generation is very important in reproducing power spectra, spatial correlation and turbulence statistics of wind velocity in LES.
Deep desulfurization of gas oil over NiMoS catalysts supported on alumina coated USY-zeolite
Nakano, K.,Ali, S.A.,Kim, H.J.,Kim, T.,Alhooshani, K.,Park, J.I.,Mochida, I. Elsevier Scientific Pub. Co 2013 Fuel processing technology Vol.116 No.-
A series of NiMoS catalysts supported on USY-zeolite coated with different amounts of alumina were prepared and evaluated for deep hydrodesulfurization (HDS) of gas oil using a flow reactor system in single- and dual-bed configurations. The performance of these catalysts was compared to the conventional HDS catalyst as well as to NiMoS catalyst supported on physical mixture of alumina and USY-zeolite. Physically mixed alumina and USY zeolite showed high HDS activity, but it was accompanied with significant cracking of hydrocarbons. Activity and kinetic analysis showed that heavy coating of alumina on the zeolite resulted in much lower HDS and cracking activity. On the other hand, very light coating of alumina on the zeolite resulted in catalytic behavior similar to that of physical mixture of USY-zeolite and alumina. The general trend was an increase in HDS as well as hydrocracking activity with the decrease in amount of alumina coating over zeolite. Changes in product density, aromatic content, mid-boiling point, cetane index, and molecular weight also reflected this trend. The results of this study indicate that catalysts with neither too low nor too high amount of alumina coating on the USY zeolite are suitable to achieve the balance between high HDS and low cracking activities. The highlight of the present study is that it confirmed the deep HDS activity of USY containing alumina supports in the flow reactor system which is industrially applied. In addition, the stability test confirmed the long-term performance of alumina-coated zeolite catalyst.
X-ray and Neutron Structure Analysis of MeHPLN in the Low Temperature Phase
R. Kiyanagi,A. Kojima,H. Kimura,M. Watanabe,S. Kumazawa,T. Sugawara,T. Hayashide,T. Mochida,Y. Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
Structure analyses of 5-Methyl-9-hydroxyphenalenon(C14H10O2, MeHPLN) in the low temperature phase were performed by X-ray and neutron scattering experiments. It is found that the space group is P21/c with a super cell (a 2b c) and there are two types of molecules in the unit cell. In one of the independent molecules, hydrogen atoms in hydrogen-bond region occupy two sites as same as in the room temperature phase. On the other hand, in another independent molecules, hydrogen atoms in hydrogen-bond region clearly show ordering feature. In these ordered hydrogen atoms, there are obvious discrepancy beween electron and nuclear distribution, and hence static electrical dipolemoments exist in hydorgen-bond region with an antiferroelectric ordering.