低温泵现场使用可靠性评价及维修保障方法

结合北京卫星环境工程研究所现有低温泵使用情况,建立低温泵任务可靠性模型,开展低温泵FMEA。对2009年—2015年的低温泵故障数据进行收集和整理,采用直方图法进行现场故障率和MTBF估计,评估低温泵现场使用可靠性水平;又通过基于P-P理论的寿命分布假设检验方法,获得低温泵现场使用寿命分布特征。根据现场可靠性分析结果并结合多年维修保障经验,给出了低温泵使用过程中常见故障的维修保证流程及方法,有助于后续真空热试验的连续实施。     

Impact of lubricant traction coefficient on cage's dynamic characteristics in high-speed angular contact ball bearing

In this paper, the formulas of elasto-hydrodynamic traction coefficients of three Chinese aviation lubricating oils, 4109, 4106 and 4050, were obtained by a great number of elasto-hydrodynamic traction tests. The nonlinear dynamics differential equations of high-speed angular contact ball bearing were built on the basis of dynamic theory of rolling bearings and solved by Gear Stiff (GSTIFF) integer algorithm with variable step. The impact of lubricant traction coeffi-cient on cage's dynamic characteristics in high-speed angular contact ball bearing was investigated, and Poincare map was used to analyze the impact of three types of aviation lubricating oils on the dynamic response of cage's mass center. And then, the period of dynamic response of cage's mass center and the slip ratio of cage were used to assess the stability of cage under various working con-ditions. The results of this paper provide the theoretical basis for the selection and application of aviation lubricating oil.     

A model for discrimination and prediction of mental workload of aircraft cockpit display interface

With respect to the ergonomic evaluation and optimization in the mental task design of the aircraft cockpit display interface, the experimental measurement and theoretical modeling of mental workload were carried out under flight simulation task conditions using the performance evaluation, subjective evaluation and physiological measurement methods. The experimental results show that with an increased mental workload, the detection accuracy of flight operation significantly reduced and the reaction time was significantly prolonged; the standard deviation of R-R intervals（SDNN） significantly decreased, while the mean heart rate exhibited little change; the score of NASA_TLX scale significantly increased. On this basis, the indexes sensitive to mental workload were screened, and an integrated model for the discrimination and prediction of mental workload of aircraft cockpit display interface was established based on the Bayesian Fisher discrimination and classification method. The original validation and cross-validation methods were employed to test the accuracy of the results of discrimination and prediction of the integrated model, and the average prediction accuracies determined by these two methods are both higher than 85%. Meanwhile, the integrated model shows a higher accuracy in discrimination and prediction of mental workload compared with single indexes. The model proposed in this paper exhibits a satisfactory coincidence with the measured data and could accurately reflect the variation characteristics of the mental workload of aircraft cockpit display interface, thus providing a basis for the ergonomic evaluation and optimization design of the aircraft cockpit display interface in the future.     

测试性建模与分析在显示控制单元中的应用

测试性分析与评估是测试性设计工作的重要环节,采用的方法一般有基于经验的加权法和基于模型的分析法。本文采用了基于模型的方法对显示控制单元的测试性进行了分析与评估,验证了显示控制单元的测试性设计指标是否达到要求,并对显示控制单元的测试性设计提出了改进建议。     

考虑表面加工缺陷的轮盘疲劳寿命分析方法

为了将表面加工状态引入零构件概率寿命分析中,提出并建立了考虑表面加工缺陷的轮盘疲劳寿命分析方法。将孔的表面加工缺陷简化为表面裂纹和/或角裂纹,导出裂纹深度密度函数;借助裂纹应力强度因子经验公式及有限元分析,提出轮盘孔边裂纹应力强度因子计算的推广经验公式方法。建立了3种考虑表面缺陷尺度分布时轮盘概率寿命计算方法。以钛合金盘为例,在获得的表面缺陷分布条件下,计算了给定寿命的轮盘疲劳寿命失效概率及故障率。仿真结果表明:采用该方法可以将表面加工缺陷对疲劳寿命的影响引入构件寿命评估体系。     

并存大角速率转动的圆锥算法精度评估

本文利用圆锥运动和大角速率转动并存条件下的规范化四元数,对扩展形式级数圆锥算法和扩展形式显式频率整形圆锥算法进行了理论误差分析,给出了理论的误差公式.针对不同条件下,即大角速率转动和圆锥频率变化时,揭示了扩展形式频率级数圆锥算法和扩展形式显式频率整形圆锥算法精度差异的原因.同时,仿真也证明了圆锥运动和大角速率转动并存条件下,扩展形式频率级数圆锥算法和扩展形式显式频率整形圆锥算法理论误差分析结果的正确性.     

任意采样率变换数字重构滤波器设计

针对理想重构函数在数字信号域不可实现而直接截取性能较差的情况,根据信号重构理论和FIR（Finite Impulse Response,有限脉冲响应）滤波器窗函数设计法,分析不同窗函数、不同截取长度对重构滤波器的影响,提出一种凯塞窗任意采样率变换数字重构滤波器设计方法.该方法通过选择合适的窗参数、截取长度、重构滤波器时域精度和量化位数,有效控制阻带最小衰减抑制数字重构镜像.设计的数字重构滤波器已成功应用于某卫星基带调制解调器,符合镜像抑制大于65 dB的性能要求.     

PMMA在固体燃料冲压发动机中燃烧特性的数值模拟

为了解PMMA在固体燃料冲压发动机燃烧室内的燃烧特性,采用RNG κ-ε模型、涡耗散湍流燃烧模型和一阶迎风格式,对以PMMA为燃料的固体燃料冲压发动机燃烧室进行了数值模拟,得到了燃烧室内的流场结构、温度及组分分布.通过比较数值计算结果与国外试验数据,验证了该数值方法的可靠性.研究表明,随着轴向位置的增大,燃料局部退移速...     

基于贝叶斯的航空备件需求研究与应用

鉴于目前航空备件需求计算应用泊松公式存在计算结果误差较大的问题,依据历史故障数据并应用广义更新过程建立反映历史故障数据以及维修能力的可靠性分布模型,同时针对目前历史故障数据主要是小样本事件,应用贝叶斯方法并采用切片采样法对可靠性分布模型进行参数估计。最后通过实例进行分析,结果表明实际故障次数和实际故障情况较为吻合,增大了模型的应用范围。     

一种离心喷嘴多孔蒸发管的蒸发率实验

发展了一种用于微小型燃气轮机燃烧室的多孔蒸发管,燃油通过离心喷嘴供入蒸发管上游,空气经喷嘴下游的多个离散小孔进入蒸发管,燃油在蒸发管内与空气混合并蒸发.测试了离心喷嘴的喷雾特性,并主要对该多孔蒸发管的燃油蒸发率进行了实验.结果表明:对于这种多孔蒸发管,影响蒸发率的主要因素是进气温度和离心喷嘴的喷雾特性,当进气温度超过4...