Utsunomiya University

About: Utsunomiya University is a education organization based out in Utsunomiya, Japan. It is known for research contribution in the topics: Laser & Holography. The organization has 4139 authors who have published 6812 publications receiving 91975 citations. The organization is also known as: Utsunomiya daigaku.

Numerical analysis of developing turbulent flow in a 180° bend tube by an algebraic Reynolds stress model

Abstract: A numerical analysis has been performed for three-dimensional developing turbulent flow in a 180° bend tube with straight inlet and outlet section used by an algebraic Reynolds stress model. To our knowledge, numerical investigations, which show the detailed comparison between calculated results and experimental data including distributions of Reynolds stresses, are few and far between. From this point of view, an algebraic Reynolds stress model in conjunction with boundary-fitted co-ordinate system is applied to a 180° bend tube in order to predict the anisotropic turbulent structure precisely. Calculated results are compared with the experimental data including distributions of Reynolds stresses. As a result of this analysis, it has been found that the calculated results show a comparatively good agreement with the experimental data of the time-averaged velocity and the secondary vectors in both the bent tube and straight outlet sections. For example, the location of the maximum streamwise velocity, which appears near the top or bottom wall in the bent tube, is predicted correctly by the present method. As for the comparison of Reynolds stresses, the present method has been found to simulate many characteristic features of streamwise normal stress and shear stresses in the bent tube qualitatively and has a tendency to under-predict its value quantitatively. Judging from the comparison between the calculated and the experimental results, the algebraic Reynolds stress model is applicable to the developing turbulent flow in a bent tube that is known as a flow with a strong convective effect. Copyright © 2005 John Wiley & Sons, Ltd.

Measurement of air shower cores to study the cosmic ray composition in the knee energy region

Abstract: Since 1996, a hybrid experiment consisting of an emulsion chamber and a burst detector array and the Tibet-II air shower array has been operated at Yangbajing (4300 m above sea level) in Tibet. This experiment can detect air-shower cores, called burst events, accompanied by air showers in excess of about 100 TeV. Using the burst event data observed by this experiment, we discuss the primary cosmic ray composition around the knee in comparison with the Monte Carlo simulations. In this paper, we show that all the features of burst events are wholly compatible with the heavy enriched composition in the knee energy region.

Congestion control for TCP/AQM networks using state predictive control

Abstract: The purpose of this paper is to design congestion controllers for TCP/AQM networks using state predictive control and to illustrate the effectiveness of the resulting congestion controllers via SIMULINK and the ns-2 simulator. Linearized models of TCP/AQM networks can be simply described as linear systems with information delay. Using state predictive control, these linear systems with an information delay are equivalent to linear systems with no delay. Thus, congestion controllers (AQM mechanisms) can be designed by using linear control theory. In this paper, LQ control with an observer is adopted for linear systems with no delay which describe linearized systems of TCP/AQM networks. Finally the designed state predictive controllers using LQ control with an observer are implemented and some simulation results obtained with SIMULINK and the ns-2 simulator are presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 41–47, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20405

Cuticular protein and transcription factor genes expressed during prepupal-pupal transition and by ecdysone pulse treatment in wing discs of Bombyx mori.

Abstract: We aimed to understand the underlying mechanism that regulates successively expressed cuticular protein (CP) genes around pupation in Bombyx mori. Quantitative PCR was conducted to clarify the expression profile of CP genes and ecdysone-responsive transcription factor (ERTF) genes around pupation. Ecdysone pulse treatment was also conducted to compare the developmental profiles and the ecdysone induction of the CP and ERTF genes. Fifty-two CP genes (RR-1 13, RR-2 18, CPG 8, CPT 3, CPFL 2, CPH 8) in wing discs of B. mori were examined. Different expression profiles were found, which suggests the existence of a mechanism that regulates CP genes. We divided the genes into five groups according to their peak stages of expression. RR-2 genes were expressed until the day of pupation and RR-1 genes were expressed before and after pupation and for longer than RR-2 genes; this suggests different construction of exo- and endocuticular layers. CPG, CPT, CPFL and CPH genes were expressed before and after pupation, which implies their involvement in both cuticular layers. Expression profiles of ERTFs corresponded with previous reports. Ecdysone pulse treatment showed that the induction of CP and ERTF genes in vitro reflected developmental expression, from which we speculated that ERTFs regulate CP gene expression around pupation.