Numerical solutions for a two-dimensional airfoil undergoing unsteady motion

Continuous vorticity panels are used to model general unsteady inviscid, incompressible, and two-dimensional flows. The geometry of the airfoil is approximated by series of short straight segments having endpoints that lie on the actual surface. A piecewise linear, continuous distribution of vorticity over the airfoil surface is used to generate disturbance flow. The no-penetration condition is imposed at the midpoint of each segment and at discrete times. The wake is simulated by a system of point vortices, which move at local fluid velocity. At each time step, a new wake panel with uniform vorticity distribution is attached to the trailing edge, and the condition of constant circulation around the airfoil and wake is imposed. A new expression for Kutta condition is developed to study (i) the effect of thickness on the lift build-up of an impulsively started airfoil, (ii) the effects of reduced frequency and heave amplitude on the thrust production of flapping airfoils, and (iii) the vortex-airfoil interaction. This work presents some hydrodynamic results for tidalstream turbine.     

Time-fuel synthetic optimal control of ship-borne special crane based on predictive average dynamic

Ship-bome special crane, a multi-joints and foldaway one, is important to study the most effective energy-saving ( i. e. synthetic time-fuel optimal) operation control mode. In this paper, by introducing weighted parameters, a time-fuel synthetic optimal criterion is obtained, and configuration of the optimal controller is verified. Furthermore, a predictive average dynamic method is put forward, and applied to treat nonlinearity and coupling of the crane. Finally, an optimal controller with feedback is designed. The validity of this approach is verified by simulation results.     

Analysis and experiment of a vessels shell cover in submarine structure

This paper aims to achieve analysis and experiment results that relate to mechanics capability and structural parameter of a special saddle shell of revolution. Theoretically speaking, the saddle shell of revolution consists of a toroidal shell and a spherical shell. The shells simultaneous equations can he solved with harmonious terms. Where, the fundamental equations can be solved by asymptotic exponential perturbation method. The equations of special solution can be solved by Hovozhilovs special solution. This new idea is from a study of some existing solutions of the toroidal shell. The results have heen proved by eompared with some experimental results. The experiments aims to study the effect caused by change of material parameter,or by change of different geometrie dimensions of the saddle shell,which include the ehange of thickness, the change of radius of shell, and the change of ribs. Finally, the accepted product of the saddle shell were reinforeed by a toroidal rib has been submitted.     

Kinematic and Kinetic Analysis for the Tilting Mechanism of Railway Passenger Cars

The kinematics and kinetics of the tilting mechanism of railway passenger cars are studied. The parameters of the mechanism are given. The motions of the actuator, the center of gravity of the carbody and the center of coupler are calculated. Finally, the maximum driving force, output power and velocity of the actuator are discussed in detail.     

大块金属玻璃的热稳定性

通过差动热分析（ＤＳＣ）试验测定了Ｚｒ－１０６合金的玻璃转变温度Ｔｇ和初始晶化温度Ｔｘ,利用Ｘ射线和透射电子显微镜（ＴＥＭ）对该合金在Ｔｇ－Ｔｘ温度区间经不同温度和不同时间热处理后试样的显微结构进行了分析,并在Ｔｇ－Ｔｘ温度区间对该合金进行热锻变形,结果表明,该合金的Ｔｇ－Ｔｘ分别为３２５℃和４７０℃,在低于晶化温度Ｔｘ以下热处理几科下不发生晶化,其厚度方向的变形量可达２００％,由此得出Ｚｒ－１０     

XML在船舶监控系统中的应用

可扩展标记语言(ExtensibleMarkupLanguage,XML)是一种与平台无关的结构化数据模型,用于解决异构平台之间的无缝连接和互操作性。主要介绍了XML在船舶监控系统中的应用,提出XML作为一种透明的元数据交换媒介,有利于实现船舶监控技术支持系统之间的兼容,描述了基于XML和HTTP协议的即时信息系统Web服务技术。     

浅谈公路双跨连拱隧道中隔墙施工技术

文章通过对连拱隧道先中导洞开挖、中隔墙混凝土灌注、中隔墙顶部混凝土回填、中隔墙防偏压处理等方面的介绍,总结了双跨连拱隧道先中隔墙施工后正洞掘进的一些经验.     

略谈毛泽东的社会主义"两阶段"论

在科学社会主义发展史上,毛泽东第一个明确提出社会主义社会分为两个阶段的思想,对马克思主义社会发展阶段理论作出了新贡献,为邓小平创立社会主义初级阶段理论提供了思想来源。     

公路隧道全射流通风压力坡度的现场测试

采用现场测试的方法研究公路隧道内全射流通风的压力分布情况。测试结果表明,隧道入口段气压高于当地大气压力,为相对正压,出口段气压低于当地大气压力,为相对负压,在隧道中存在一个与大气压力相等的点,即相对压力为0的点。本次现场测试可为全射流纵向通风的设计提供参考。     

门架式围护结构在开挖基坑中的应用与研究

介绍天津“城市之星”商住楼基坑围护结构,采用门架式围护结构的设计、施工、变形观测和应用效果。