涡轮转子H形叶片叶尖间隙测量

叶尖间隙是燃气轮机中的一个重要性能参数和安全监测参数。现代燃气轮机中采用H形凹腔冷却涡轮叶片,该叶片具有单叶片双间隙的特点。利用电容式叶尖间隙测量系统,通过改进算法,实现了H形叶片的叶尖间隙测量,并成功应用于H形叶片涡轮级性能试验。试验录取了三种不同设计间隙下的实际叶尖间隙变化数据,分析了叶尖间隙与涡轮性能之间的关系,并对试验中的转子异常运动进行了成功监测。     

基于四线制的电阻自动测量研究与实现

为了实现对多型座椅不同组件电气性能的自动测量,需要研制座椅电气自动综合检测设备。针对座椅组件电阻测量的导通性指标测试任务,提出了一种基于工控机、信号切换模块、数字多用表和通用连接模块的测试方案,并开发了自动测试控制程序,实现了对多型座椅电气组件电阻的快速准确自动检测。     

Convergence Analysis of the Numerical Solution for Cathode Design of Aero-engine Blades in Electrochemical Machining

As a main difficult problem encountered in electrochemical machining （ECM）, the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the machining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.     

Quality assessment of sub-Nyquist recovery from future gravity satellite missions

Drawing on experience from Gravity Recovery and Climate Experiment (GRACE) data analysis, the scientific challenges were already identified in several studies. Any future mission should focus on improvement in both precision and resolution in space and time. For future gravity missions which use high quality sensors, aliasing of high frequency time-variable geophysical signals to the lower frequency signals is one of the most serious problems. The aliasing problem and the spatio-temporal resolution are mainly restricted by two sampling theorems describing the space-time sampling of satellite missions: (i) a Heisenberg-like uncertainty theorem which states that the product of spatial resolution and time resolution is constant, and (ii) the Colombo–Nyquist rule (CNR), which requires the number of satellite revolutions in a repeat period to be at least twice a given maximum spherical harmonic degree. The CNR holds under the assumption of equal ground-track spacing, and limits the spatial resolution of the gravity solution.     

计算机局域网安全隐患及防护

通过阐述目前的网络安全现状,分析可能存在的网络安全隐患,介绍现有比较成熟的安全技术,从而探讨保障企业网络安全的技术措施.     

弧线齿面齿轮齿面接触分析

为了提高面齿轮副的强度并解决其磨齿问题,提出了弧线齿面齿轮副的一种新的加工方法,并研究其啮合特性.用有刀倾的刀盘旋转而成的切削面作为假想齿轮的齿面,模拟产形齿轮和被加工齿轮啮合过程.推导弧线齿面齿轮副齿面方程;根据两齿面在啮合过程中连续相切条件.建立了考虑安装误差的轮齿接触分析(TCA)模型;齿轮副计算机啮合仿真结果表...     

航空机务维修差错的分析及预防措施

航空机务维修差错会直接导致飞行事故,这是毋容置疑的。在分析全空军过去机务维修差错具体原因的基础上,结合新机装备及其维修特点,提出新形势下如何贯彻落实航空装备维修安全观和积极预防航空机务维修差错的具体措施,以确保飞行安全。     

传感器位置误差条件下的约束总体最小二乘时差定位算法

 现代定位系统中,传感器往往被安放在运动平台上,其位置无法精确得知,存在估计误差,将严重影响对目标的定位精度。针对这一问题,提出基于约束总体最小二乘(CTLS)的到达时差(TDOA)定位算法。首先通过引入中间变量,将非线性TDOA定位方程转化为伪线性方程,再利用CTLS技术,全面考虑伪线性方程所有系数中的噪声。在此基础上推导了定位方程的目标函数,再根据牛顿迭代方法,进行数值迭代,快速得到精确解。采用一阶小噪声扰动分析方法,对该算法的理论性能进行了分析,证明了算法的无偏性和逼近克拉美-罗下限(CRLB)。仿真实验表明,该算法克服了现有总体最小二乘(TLS)算法不能达到CRLB、两步加权最小二乘(two-step WLS)算法在较高噪声时性能发散的缺陷,在较高噪声时定位精度仍然能达到CRLB。     

Safety estimation of structural systems via interval analysis

Considering that the uncertain information has serious influences on the safety of structural systems and is always limited, it is reasonable that the uncertainties are generally described as interval sets. Based on the non-probabilistic set-theoretic theory, which is applied to measuring the safety of structural components and further combined with the branch-and-bound method for the probabilistic reliability analysis of structural systems, the non-probabilistic branch-and-bound method for determining the dominant failure modes of an uncertain structural system is given. Meanwhile, a new system safety measuring index obtained by the non-probabilistic set-theoretic model is investigated. Moreover, the compatibility between the classical probabilistic model as well as the proposed interval-set model will be discussed to verify the physical meaning of the safety measure in this paper. Some numerical examples are utilized to illustrate the validity and feasibility of the developed method.     

交流对机组失误的影响

分析了团队失误产生的一般过程，发现加强交流管理可以有效改善团队工作的整个过程，从而降低人为失误的发生．指出造成机组交流缺陷的多种原因．给出实际可行的交流方法以减少机组失误的产生。