自锐式斜齿柔性砂带轮及其磨抛机理

提出自制的柔性砂带轮，它是用于零件曲表面磨削抛光的新型磨具．该柔性砂带轮的优点是：磨抛噪声低；砂带利用率高；更换周期长。本文给出了该磨具的结构原理，并对其磨抛机理进行了分析探讨．     

Nonlinear Dynamic Analysis of Flexible Marine-Risers

A nonlinear dynamic analysis model is estabilished on the basis of "lumped mass" approach, which takes the influence of the fluid flow within the pipe into consideration. Numerical results are compared with the published works, and the effects of internal fluid flow, internal pressure, dyanmics as well as the nonlinear characteristics on the behavior of flexible risers are discussed. From this work, some useful conclusions are drawn.     

水下柔性鱼形机构原理及单尾鳍板水动力试验研究

柔性鱼形机构是模拟鱼类运动的一种仿生机械系统。对鱼类运动的观察与研究 ,实质上是寻求水域中最优推进形式的过程 ,是工程优化设计的途径之一。在研究及优化柔性鱼形机构时涉及到水动力学及控制模型的问题 ,因此取出鱼形机构的尾鳍部分进行敞水试验 ,既能为有关模型的建立提供依据 ,更重要的是对鱼形机构的可行性进行论证     

New Method for Predicting the Motion Responses of A Flexible Joint Multi-Body Floating System to Irregular Waves

A new hybrid method of frequency domain and time domain is developed in this paper to predict the motion responses of a flexibly joint multi-body floating system to irregular waves. The main idea of the method is that the three-dimensional frequency method is used to obtain the hydrodynamic coefficients and the response equations are solved in time domain step by step. All the forces can be obtained at the same time. The motions and nonlinear mooring forces of a box type six-body floating system are predicted. A comparison of the theoretical method-based solutions with experimental results has shown good agreement.     

Nonlinear Behaviour of Coflexip Risers

A modified Newton-Raphson iterative technique is formulated for obtaining the static configuration of the Lazy "S" flexible marine riser between the floater and mid-arch buoy under its submerged self weight and the applied top tension. The geometrically non-linear problem is solved by finite difference with the above technique. The problem is formulated as a regular boundary value problem with specified moments and deflections at both ends. Usually the bending stiffness of the flexible riser made of Coflexip pipe is very low. By use of the above analysis, several flexible riser configurations are analyzed and their characteristic behaviors are investigated. Also, changes in the riser characteristics due to quasi-static motion of the floater end are estimated for the safety of the riser layout.     

Discrete Element with Flexible Connector for Dynamic Analysis of 3-D Beam Structures

Combined multi-body dynamics with structural dynamics,a new discrete element with flexibleconnector,which is applicable for 3-D beam structures,is developed in this paper.Both the generalizedelastic coefficient matrix of the flexible connector and the mass matrix of discrete element may be off-diag-onal in a general case.The zero-length rigid element is introduced to simulate the node at which multiple el-ements are jointed together.It may also be effective when the axes of adjacent elements are not in the sameline.The examples for eigenvalue calculation show that the model is successful.It can be extended to thegeometric nonlinear response analysis.     

基于实密度的卧式浪流轮机水槽实验研究分析

实密度是影响轮机获能特性的关键因素之一。文中以卧式轮机实密度为基变量,以其获能系数为主要考察点,对3种实密度卧式轮机进行水槽实验方案设计和水动力性能研究。实验分别对水流流速、轮机旋转角速度、主轴转矩以及功率进行测量,并对其对主轴的扭矩、轮机的获能系数以及叶片的旋转特性进行定量分析,最终证实了该卧式轮机的单一运行特性。通过绘制基于实密度的轮机转矩—转角曲线、获能系数—尖速比曲线和轮机功率—尖速比曲线,阐明了实密度影响卧式轮机获能水动力性能的规律,即其获能系数和发电功率都随着工况速比呈先增后降趋势。实密度较低轮机因浪流流失而获得能量小,但实密度过高轮机会导致叶片间湍流涌动,加速叶片失速特性而影响轮机获能。这为卧式浪流轮机结构优化提供了可靠依据和借鉴。     

Teaching Historical Geographies of American Film Production

Abstract

The geographies of Hollywood are multiple, contradictory, ephemeral and tangible. Our preconceived conceptions of space and place play a dynamic role in what elements we tend to focus on when discussing the cultural industry of American cinema. This essay uses Hollywood as a metaphor for the American film production industry and a historical geography of production as a framework to explore major spatial and structural changes within this industry from its inception to the present. It highlights teaching methods and materials from the course A Geography of Film at Southern Connecticut State University. Mode of production relates to the economic process where capital, labor, knowledge and imagination are blended to produce a culturalized product for consumption. The American film industry is a fine example of the commodification of culture.     

褥垫层地复合地基受力模式的影响及工程实例分析

采用复合地基方案时，在基础和复合地基之间可设一层粒状材料垫层，以起“调整均化”作用。本文通过分析褥垫层对复合地基受力模式的影响，探讨了褥垫层在保证桩土共同承担荷载，改善复合地基承载性状等方面所具有的重要意义。最后通过对某具体工程实例的分析，得出一些相关结论。