Application of large eddy simulation in the performance study of wave blocker

The configuration and aerodynamic performance of the inlet system are important aspects in the process of installing a gas turbine on a naval vessel. Under the requirements, large eddy simulation （LES） is used to simulate the three-dimensional fluid flow in the wave blocker of a marine inlet filter. The Smagorinsky-Lilly sub-grid model was used to model motions of small-scale structures. During numerical simulation, the SIMPLE algorithm was applied. The central-differencing spatial discretization scheme and the second order accuracy finite difference for the temporal discretization were used. Simulation gives satisfactory distribution of the vorticity fields and turbulent kinetic energy. Compared with the k-ε turbulent model, the results of LES are better for the distribution of parameters. The results of experimental study in a small-scale wind tunnel indicate that numerical calculation has higher accuracy. Therefore, the methods used are worthy of reference and introduction for the design of an inlet system.     

The measure and decision of technical risk in the development of naval vessels

The risks in development of navy vessels were explored, The resources of technical risk in the design and development of vessels were mentioned, It was pointed that technical risk dominated the other risk components. Based on the writers＇ understanding and experience from risk analysis and risk ,nanagement to the development of a navy vessel, four measure indexes of technical risk were presented. The decision criteria and the rules corresponding to the indexes were estahlished by the statistic information,     

Study of the helicopter blade running elevation measurement system

Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter＇ s security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, tire design of the measurement system and analysis of the measurement precision.     

Sensitivity analysis and dynamic modification of modal parameter in mechanical transmission system

Sensitivity analysis is one of the effective methods in the dynamic modification. The sensitivity of the modal parameters such as the natural frequencies and mode shapes in undamped free vibration of mechanical transmission system is analyzed in this paper. In particular,the sensitivities of the modal parameters to physical parameters of shaft system such as the inertia and stiffness are given. A calculation formula for dynamic modification is presented based on the analysis of modal parameter. With a mechanical transmission system as an example, the sensitivities of natural frequencies and modes shape are calculated and analyzed. Furthermore, the dynamic modification is also carried out and a good result is obtained.     

Market based framework for multiple AUVs cooperation

A“Market” based framework for multiple AUVs team is introduced in this paper. It is a distributed meta-level task allocation framwork. The formulation and the basic concepts of the “Market” such as “goods” and “price” are discussed first, then the basic algorithm of the “auction”. The loosely coupled v-MDTSP tasks are considered as an example of the task allocation mission. A multiple AUV team controller and a detailed algorithm are developed for such applications. The simulation results show that the controller has the advantages such as robustness and low complexity and it can achieve better optimization results than the classical central controller （ such as GA） in some tasks. And the comparison of two different local solvers also implies that we should get the reasonable task allocation even not using the high quality algorithm, which can considerably decrease the cooperation computation.     

简易智能电动车的设计

所设计的小车,是采用普通玩具小车和红外传感器、光敏元件、金属探测器、光电开关以及霍尔元件相结合,通过16住MCU-SPCE061A来调控的智能小车．小车主控系统中采用16位的陵阳单片机SPCE061A做CPU,具有运算速度快、结构简单、电机控制快速准确、行走稳定等优点,并带有语音播放功能．     

石灰改良软土作路基填料在饱水条件下的强度特性研究

通过界限含水量试验、重型击实试验,研究了不同掺灰比对石灰改良土液、塑限、最大干密度、最优含水量的影响;模拟现场条件,利用固结不排水三轴试验,研究了石灰改良土在饱水养生条件下的强度特性,并得出了一些对工程有益的结论。     

三次样条插值确定拱桥合理拱轴线的方法探讨

探讨了在拱桥设计中利用给定的设计初始条件,计算出合理拱轴线的特征点坐标,应用三次样条插值方法拟合出拱桥设计拱轴线,算例表明三次样条插值方法确定的拱轴线能较精确地逼近拱桥的恒载压力线,从而有效地减少拱桥主拱圈的弯距及剪力。     

一般Clean环的扩张

有单位元的结合环R称为clean环,如果R中的每个元素都可以写成一个幂等元与一个单位的和的形式.W.K.Nicholson,Y.Zhou[1]给出了一般clean环的定义.在此基础上讨论了一般clean环的几个扩张性质,得到如下结论:1)一般环I是一般clean环当且仅当I的形式幂级数环是一般clean环当且仅当I的斜幂级数环是一般clean环.2)若I是一般clean环,则对任意n≥1,均有I[x]/是一般clean环.     

武广客运专线CFG桩质量检测与评价

武广客运专线武汉工程试验段应用CFG桩加固处理松软地基,采用单桩静载荷试验、单桩复合地基静载荷试验、低应变反射波法和钻芯检测桩的质量。通过试验和分析,结果表明,CFG桩复合地基能达到设计要求,可有效地增强地基承载力和控制工后沉降值。