Sensitivity Analysis and Optimization of Geometric Parameters of a New Fluid Bag Buffer Mechanism on Buffering Performance

A new fluid bag buffer mechanism,which can provide large axial stiffness under the small displacement,is designed.The dynamic change laws of the mechanism stiffness and the internal pressure of the fluid bag are studied when it is subjected to impact load.According to the protection performance for the flexible joint and the pressure change in the fluid bag during the impact process,the sensitivity of the geometric parameters of the fluid bag to the axial stiffness is analyzed by using the orthogonal experimental method,and the optimal parameter combination of the geometric parameters of the fluid bag under impact is obtained,leading to the displacement of the inner shell reduce by 41.4%.The results show that the internal pressure of the fluid bag is a rising process of oscillation and fluctuation.The sensitivity of the geometric parameters of the fluid bag to the displacement of the inner shell from high to low is as follows:Height H,radius r,wall thickness t,chamfer A.The correlation between the geometric parameters of the fluid bag and its internal pressure is:H is negatively correlated with the internal pressure,while the r,t,and A are positively correlated with the internal pressure.

Dynamic model and performance analysis of landing buffer for bionic locust mechanism

The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed.Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance,and it establishes a theoretical basis for studies and engineering applications.

Practice Mode and Value Research of Reform of Rural Collective Economy Property Right System in Beijing Rural-urban Continuum

In the research, reform of rural collective economy property right system in Beijing rural-urban continuum was explored in terms of background, cause, pro- cess and practice modes by surveying and interviewing, and the value of system reform on urbanization in rural areas was illustrated from the perspective of farmers who lose lands. The results showed that since reform and opening-up, disadvan- tages of collective economy property are always the fundamental cause of reform; rural-urban contradiction produced from rapid urbanization makes the reform much more urgent; shareholding co-operative system is the essence of reform of collective economy property right system. Rural collective economy property right system in Beijing includes stock-assets quantification shareholding co-operative system, share- capitalization of contractual land management right, farmers as shareholders by investment, and resource and capital mode, with advantages and disadvantages respectively. The common character should be noticed is that all modes have share on contractual right of land, indicating the core of the reform of property system lies in asset quantification and stock quota. In improving urban-rural integration and modern market system, as well as endowing more rights to farmers, reform of rural collective economy property right system is of great significance, which provides a transition space and buffer mechanism for urbanization in rural areas.

空间对接机构差动式机电缓冲阻尼系统机构传动原理分析

对空间对接机构中差动式机电缓冲阻尼系统的基本构成、系统主要部件及其在各种工作模式下的机构传动原理进行了较为深入的探讨．基本上搞清楚了差动式机构的结构原理，这是研究对接机构系统必须突破的一项关键技术．

Modeling of titration experiments by a reactive transport model

Acid mine drainage（AMD） is commonly treated by neutralization with alkaline substances.This treatment is supported by titration experiments that illustrate the buffering mechanisms and estimate the base neutralization capacity（BNC） of the AMD.Detailed explanation of titration curves requires modeling with a hydro-chemical model.In this study the titration curves of water samples from the drainage of the As Pontes mine and the corresponding dumps have been investigated and six buffers are selerted by analyzing those curves.Titration curves have been simulated by a reactive transport model to discover the detailed buffering mechanisms.These simulations show seven regions involving different buffering mechanism.The BNC is primarily from buffers of dissolved Fe,Al and hydrogen sulfate.The BNC can be approximated by：BNC = 3（C_（Fe） ＋ C_（Al）） ＋ 0.05C_（sulfate）,where the units are mol/L.The BNC of the sample from the mine is 9.25×10^（-3） mol/L and that of the dumps sample is 1.28×10^（-2） mol/L