Research on Maintainability Evaluation Model Based on Fuzzy Theory

分析了产品维修性影响属性,给出了维修性属性值与权重的确定方法;提出了基于相对接近度的维修性模糊评价方法。以虚拟环境下产品维修过程为研究对象,在分析产品各可更换单元的维修作业的基础上,建立了产品维修性评价模型。最后结合民机主起落架系统给出了应用实例,结果表明该模型适用于产品维修性的定性评价并且能够支持维修性并行设计。     

RPC-MIP: the Mutual Impedance Probe of the Rosetta Plasma Consortium

The main objective of the Mutual Impedance Probe (MIP), part of the Rosetta Plasma Consortium (RPC), is to measure the electron density and temperature of Comet 67P/Churyumov-Gerasimenko’s coma, in particular inside the contact surface. Furthermore, MIP will determine the bulk velocity of the ionised outflowing atmosphere, define the spectral distribution of natural plasma waves, and monitor dust and gas activities around the nucleus. The MIP instrumentation consists of an electronics board for signal processing in the 7 kHz to 3.5 MHz range and a sensor unit of two receiving and two transmitting electrodes mounted on a 1-m long bar. In addition, the Langmuir probe of the RPC/LAP instrument that is at about 4 m from the MIP sensor can be used as a transmitter (in place of the MIP ones) and MIP as a receiver in order to have access to the density and temperature of plasmas at higher Debye lengths than those for which the MIP is originally designed.     

巷道式堆垛机自控系统设计中有关问题的研究

本文就巷道式堆垛机自控系统设计中的几个问题如堆垛机信息显示及作业地址、作业指令的输入方法；位置检测、定位方法、变频器的使用等问题进行分析和研究，并提出了自己的观点和设计方案。     

发动机生产加工中质量控制界限的优化

以两类错误损失费用最小为目标,对现行发动机零组件加工质量控制中以x±3σ作为控制图控制界限的方法进行了改进,建立了确定最佳控制界限(Kσ)的数学模型与最优控制界限(K)的算式。通过实例对优化结果和现行“x±3σ”方法的结果进行了比较和分析,进一步说明了该方法的优越性。     

一类中立型高维周期微分系统的周期解

文中利用指数型二分法,结合不动点定理考虑如下形式的中立型高维周期系统: 苦d/dt[x(t)+cx1]=A(t,x(t))x(t)+f(t,x1),得到其T-周期解存在的充分性条件,所得结论改进或推广了早先文献中周期解存在的相应结论。     

直升机砂尘环境试验风洞的温度控制及仿真

 直升机砂尘环境试验风洞内部的热负荷变化范围较大,高低热负荷工况下需要采取不同的调温措施,为了简便地解决其温度控制难题,在对其温度变化进行动态特性分析与建模的基础上,提出了一种引入风速协调因子的砂尘环境试验风洞温度控制策略,并对其控制效果进行了仿真研究,仿真结果表明这一控制策略能在不同的热负荷条件下有效协调加热与制冷两种作用相反的控制措施,并将风洞内的温度控制在要求范围内。     

Singularity radius gradient-based rapid singularity-escape steering law for SGCMGs

In order to visualize singularity of SGCMGs in gimbal angle space, a novel continuous bounded singularity parameter--Singularity Radius, whose sign can distinctly determine singularity type, is proposed. Then a rapid singularity-escape steering law is proposed basing on gradient of Singularity Radius and residual base vector to drive the SGCMG system to neighboring singular boundary, and quickly escape elliptic singularities. Finally, simulation results on Pyramid-type and skew-type configuration demonstrate the effectiveness and rapidness of the proposed steering law.     

硅微静电悬浮陀螺微位移检测电路噪声分析

硅微静电悬浮惯性仪表主要面向空间应用,如卫星无拖曳控制,星载重力测量等,具有潜在分辨率高、功耗低、体积小、多轴集成等特点。仪表的高分辨率实现对检测电路的噪声提出了较高要求。本文以硅微静电悬浮陀螺仪单频调幅电容式微位移检测电路为例,从电路外部干扰噪声耦合机理及抑制、电路内部噪声分析及优化两个方面,给出了电源耦合噪声、电路温度特性以及放大器电路噪声分析优化等方面的理论推导、仿真及实验验证。     

Effects of adiabaticity and non-adiabaticity of dust charge fluctuation on the propagation of the dust ion acoustic waves in inhomogeneous dusty plasma

A theoretical investigation has been made for adiabatic positive and negative dust charge fluctuations on the propagation of dust-ion acoustic waves (DIAWs) in a weakly inhomogeneous, collisionless, unmagnetized dusty plasmas consisting of cold positive ions, stationary positively and negatively charged dust particles and isothermal electrons. The reductive perturbation method is employed to reduce the basic set of fluid equations to the variable coefficients Korteweg–de Vries (KdV) equation. Either compressive or rarefactive solitons are shown to exist depending on the critical value of the ion density, which in turn, depends on the inhomogeneous distribution of the ion. The dissipative effects of non-adiabatic dust charge variation has been studied which cause generation of dust ion acoustic shock waves governed by KdV-Burger (KdVB) equation. The results of the present investigation may be applicable to some dusty plasma environments, such as dusty plasma existing in polar mesosphere region.     

汉英旅游文本主要差异及其翻译

提高旅游资料的翻译质量能推进中国旅游业的发展。通过分析中英文旅游资料各自的文本类型特点以及中西文化的差异,本文提出了若干个相应的翻译原则和技巧。这些技巧和原则包括:删减与调整、增词法、类比法、解释法。娴熟地运用这些技巧可以提高翻译质量从而使不同的文化得到更好的交流和沟通。