Variational principles in water-wave problems (wave radiation conditions and their variational treatment)

To discuss water-wave problems in unlimited waters, it is important to know what type of wave radiation condition should be placed on a virtual surface corresponding to infinity. For this kind of problem, the Sommerfeld radiation condition is well known. In this article, the condition is extended to treat a case with an incident wave. Furthermore, a more general wave radiation condition is introduced from a different point of view. The above-mentioned wave radiation conditions are introduced into the variational principles of the Kelvin, Hellinnger–Reissner, and Dirichlet type. The Dirichlet-type variational principles are then used in numerical calculations for bending waves in a bar, and the effectiveness of the wave radiation conditions and the variational principles is shown. The numerical results for one-dimensional water-wave problems are then given. As expected, the region required for the numerical solution is reduced drastically compared with that required by the Sommerfeld-type formulation. Furthermore, the amplitude of the diverging wave is obtained in the process of reaching the variational solution. Finally, two-dimensional water-wave problems are briefly discussed. Received: August 9, 2001 / Accepted: September 17, 2001     

为新干线高速运行而开发的基础制动装置

介绍了为新干线开发的中心安装制动盘、均衡压力制动闸片和气动夹钳相结合的新型制动装置,经过试验台试验和实际FASTECH列车运行试验,证实这种新型制动装置达到了所要求的性能。对该新型制动装置进行了改进,以降低噪声。     

Experimental Study on Heat Transfer Enhancement of Natural Circulation Liquid Cooling System for Electronic Component

NomenclatureH :height of condenser above the evaporatorlevel( m)h:heightof FC- 72 filled in the testloop( m)q:heat flux based on projected surface area( W/cm2 )q CHF:critical heat flux( W/cm2 )Tc:cooling water temperature(°C)Ts:saturation temperature(°C)Tw:wall temperature(°C)ΔTsat:wall superheat( K)ΔTsub:liquid subcooling( K)W:flow rate of FC- 72 ( g/min)z:height of liquid in the downcomer( m)IntroductionDirect or indirect liquid cooling with phase-change by use of dielectric liq…     

单细胞凝胶电泳技术检测小鼠成纤维细胞DNA的氧化损伤及修复

目的观察小鼠成纤维细胞由过氧化氢(H2O2)引起的DNA损伤及其修复,并详细介绍单细胞凝胶电泳技术。方法培养NIH3T3细胞,H2O2造成细胞氧化损伤,单细胞凝胶电泳技术(SCGE,Comet Assay)检测细胞DNA的损伤情况。结果①建立了H2O2致NIH3T3细胞DNA损伤的分级图谱;②H2O2引起的小鼠成纤维细胞DNA单链断裂与H2O2的浓度呈依赖性关系;③细胞在除去H2O2后15 min已出现明显修复,多数修复可在1 h内完成,但少数修复可能需要较长时间才能完成。结论单细胞凝胶电泳技术是一种简便、敏感的检测DNA氧化损伤的方法。     

Optimum routing of a sailing wind farm

To acquire the wind energy of the oceans, a sailing wind farm has been proposed. The wind farm considered is composed of a semisubmersible floating structure, 11 windmills, four sails, six thrusters, and storage for hydrogen. To maximize the acquired energy, an effective algorithm to search for optimum routes was developed. The algorithm is based on the fact that beam winds yield a maximum of acquired energy. This feature reduces the computation time, and, consequently, efficient route optimization becomes possible in a reasonable time. After setting an operational area for the wind farm, navigation simulations for a 1-year period were carried out. A numerical weather forecast was used as well as the responses of the floating structure, such as the speed of the structure, the output power of the windmills, and the time of course changes. In the simulation, the wind farm evades rough seas to avoid structural damage, and an optimum route is searched for. The capacity factor of the system was used to evaluate the efficiency of the optimized routes. From the simulations, the maximum capacity factor achieved was 42.6%. The dependency of the capacity factor on the initial position of the wind farm was also examined. It was shown that offshore from Sanriku in northeastern Japan is an area suited to the operation of the wind farm. The effect of the initial position on consecutive periods of operation is discussed.     

Solutions for urban traffic issues by ITS technologies

In recent years, traffic congestion, traffic accidents, and deterioration of the environment because of growing population, increasing urbanization, and increasing car ownership have become serious problems in the Asia-Pacific regions. Intelligent transport systems (ITS) are systems that try to solve various road traffic issues using information communication technologies. Several countries are endeavoring to solve such traffic issues by deploying an ITS and achieving positive results. However, there are some problems in advancing ITS deployment in these countries, such as lack of technical know-how, a lack of coordination among systems, lack of a master plan, and financial constraints. In order to introduce ITSs, it is important to select suitable technologies and applications appropriate for each country. An appropriate plan and evaluation of the ITS project are also important for the introduction of ITS.In this paper, we propose methods for the utilization and introduction of ITS technologies to solve urban traffic issues in various countries, based on the lessons learned from the deployment of an ITS in Japan.     

最近的铁道车辆技术

介绍了日本铁道综合技术研究所在铁道车辆技术方面的5项课题中所取得的成就,包括导向转向架、客车车厢内的降噪技术、车辆的动力学仿真、永磁同步电动机、车辆技术开发过程中用于闭环仿真的硬件等。其中前景看好的永磁同步电动机已取得了很大进展。     

On the hydroelastic responses of a very large floating structure in waves

New numerical methods are presented for hydroelastic analyses of a very large floating structure (VLFS) of several kilometers length and width. Several methods are presented that accelerate computation without an appreciable loss of accuracy. The accuracy and efficiency of the proposed methods are validated through comparisons with other numerical results as well as with existing experimental results. After confirming the effectiveness of the methods presented, various characteristics of the hydroelastic behavior of VLFSs are examined, using the proposed methods as numerical tools. Received for publication on Dec. 3, 1999; accepted on Dec. 15, 1999