Numerical studies on four-engine rocket exhaust plume impinging on flame deflectors with afterburning

This paper studies the four-engine liquid rocket flow field during the launching phase. Using three-dimensional compressible Navier-Stokes equations and two-equation realizable k-epsilon turbulence model, an impact model is established and flow fields of plume impinging on the two different shapes of flame deflectors, including wedge-shaped flame deflector and cone-shaped flame deflector, are calcu-lated. The finite-rate chemical kinetics is used to track chemical reactions. The simulation results show that afterburning mainly occurs in the mixed layer. And the region of peak pressure occurs directly under the rocket nozzle, which is the result of the direct impact of exhaust plume. Compared with the wedge-shaped flame deflector, the cone-shaped flame deflector has great performance on guiding exhaust gas. The wedge-shaped and cone-shaped flame deflectors guide the supersonic exhaust plume away from the impingement point with two directions and circumferential direction, respectively. The maximum pressure and temperature on the wedge-shaped flame deflector surface are 37.2% and 9.9% higher than those for the cone-shaped flame deflector. The results provide engineering guidance and theoretical significance for design in flame deflector of the launch platforms.     

Analysis of a production system in a general configuration

We consider a production system comprising multiple stations (or workshops) such as an entry station, a set of work stations, a central station, and an exit station, which are arranged in a general configuration. A worker (or a vehicle tool) is assigned to each station, who sends a part from the station to the destination station according to the required process path of the part. Any part is allowed to visit a work station more than once if its process path requires. We propose a new control strategy with the push policy for instructing each worker to send a part and the kanban mechanism for controlling the work‐in‐process (WIP) in each work station. As all work stations have limited local buffers, the central station is used for storing blocked parts temporarily. Such a production system is modeled as an open queueing network in a general configuration with a Markovian part sending policy and a machine no blocking mechanism. The queueing network is analytically characterized. Some important performance measures are compared with other control strategies. A semi‐open decomposition approach is applied to the queueing network for computing the blocking probabilities when parts arrive at the work stations. An algorithm is developed based on the semi‐open decomposition approach. Numerical experiments show the quality of the solutions obtained by the algorithm as well as a property of a performance measure. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 128–143, 2001     

在发展市场经济中保持社会主义文化的先进性

市场经济对社会主义文化发展有正面效应和负面影响 ,社会主义文化有商品属性和社会属性 ,在社会主义文化的产业性与先进性、市场导向与发展方向之间存在着相互偏离的可能 ,我们党要始终“代表中国先进文化的前进方向” ,必须自觉遵循文化生产的价值规律 ,建立和完善既同发展市场经济相协调、又能保证实现社会主义文化先进性的体制和机制。     

政治工作的发展创新和与时俱进

如何将我军政治工作的优势带入 2 1世纪 ,很重要的一个问题就是要解决与时俱进的问题。只有这样 ,才能使政治工作获得进一步的发展。当前要着重解决的问题是 :充分认识新事物的积极影响 ,发挥思想教育的引导功能 ;充分认识新时期文化反哺现象日益突出的特点 ,增强教学相长的自觉性 ;充分认识世界的多样性 ,坚持运用多值思维看问题 ;充分认识教育者信息优先权丧失的现状 ,善于运用新技术 ,通过不断提高自己来获得思想教育的主动权 ;充分认识人们着重“相对报酬”的现实 ,把公平原则贯穿于政治工作全过程。     

英语军语的语言特征

军语即军事术语 ,它是表述军事概念的词语 ,是英语军事语言中的重要组成部分 .英语军语在使用上具有统一性、简明性和不可替代性 ;在意义上具有单义性、准确性和特义性 ;在形式上多使用复合词、缩略语和简明口语     

应用虚拟样机技术优化设计卡钳

分析了传统设计方法的弊端,介绍虚拟样机技术这一全新的设计方法.以应用动力学仿真软件ADAMS建造卡钳虚拟样机优化设计的实例,说明虚拟样机技术可以缩短开发周期、降低成本,提高设计质量和可靠性.     

积极推进旅团有关事务办事公开

推进旅团级单位有关事务办事公开,是我军基层民主建设的一项制度创新.要从端正官兵思想认识入手,着力改进办事公开的运行方式,正确把握办事公开的政策界限,深入推进办事公开工作的经常化、制度化、规范化.     

Optimal allocation of minimal repairs in parallel and series systems

In reliability engineering, the concept of minimal repair describes that the repair brings the failed unit (eg, system or component) to the situation which is same as it was just before the failure. With the help of the well‐known Gamma‐Poisson relationship, this paper investigates optimal allocation strategies of minimal repairs for parallel and series systems through implementing stochastic comparisons of various allocation policies in terms of the hazard rate, the reversed hazard rate, and the likelihood ratio orderings. Numerical examples are presented to illustrate these findings as well. These results not only strengthen and generalize some known ones in the seminal work of Shaked and Shanthikumar, but also solve the open problems proposed by Chahkandi et al.'s study and Arriaza et al.'s study.     

新时期加强民用车辆征用工作的几点思考

本文通过对民用车辆征用工作现状和存在问题的分析，从如何明确民用车辆征用需求、掌握民用车辆资源潜力、确定民用车辆征用标准、加强征用演练以及做好征用预案编制工作等方面提出了一些对策建议。     

无损检测及质量控制

本文介绍了无损检测技术的科学性,应用无损检测技术的重要性,实施无损检测质量控制的必要性,以及军事代表对特种检测监督的程序,并对其他各个领域实施全面质量控制具有一定的指导和借鉴作用。