4点弯曲载荷作用下残余应力与弹性模量比对涂层/基体材料界面能量释放率的影响

采用有限元计算方法研究了在4点弯曲载荷作用下,残余应力、涂层与基体的弹性模量比(简称弹性模量比)对涂层/基体材料界面能量释放率及其相角的影响。结果表明:能量释放率随着残余拉应力、弹性模量比的增大而增大;能量释放率中的相角也随着残余拉应力的增大而增大,但并不敏感,其随着弹性模量比的增大而减小。研究结果可为评价涂层/基体材料界面结合性能提供理论依据,有助于深化对涂层/基体材料界面结合性能的认识。     

基于Matlab/Simulink的燃气轮机数控仿真研究

阐述了燃气轮机控制过程,提出了3轴燃气轮机数控系统的仿真模型,并运用Matlab/Simulink工具对燃气轮机的加速过程进行仿真,分析了选择不同参数值对系统性能的影响,从中得出参数的最优值.     

On the application and extension of system signatures in engineering reliability

Following a review of the basic ideas in structural reliability, including signature‐based representation and preservation theorems for systems whose components have independent and identically distributed (i.i.d.) lifetimes, extensions that apply to the comparison of coherent systems of different sizes, and stochastic mixtures of them, are obtained. It is then shown that these results may be extended to vectors of exchangeable random lifetimes. In particular, for arbitrary systems of sizes m < n with exchangeable component lifetimes, it is shown that the distribution of an m‐component system's lifetime can be written as a mixture of the distributions of k‐out‐of‐n systems. When the system has n components, the vector of coefficients in this mixture representation is precisely the signature of the system defined in Samaniego, IEEE Trans Reliabil R–34 (1985) 69–72. These mixture representations are then used to obtain new stochastic ordering properties for coherent or mixed systems of different sizes. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Effect of particle gradation of aluminum on the explosion field pressure and temperature of RDX-based explosives in vacuum and air atmosphere

To optimize the energy output and improve the energy utilization efficiency of an aluminized explosive, an explosion device was developed and used to investigate the detonation pressure and temperature of R1 (Al6) aluminum powder and the aluminum powder particle gradation of R2 (Al6+Al13), R3 (Al6+Al24) and R4 (Al6+Al flake) in a confined space. By using gas chromatography, quantitative analysis and calculations were carried out to analyze the gaseous detonation products. Finally, the reaction ratios of the aluminum powder and the explosion reaction equations were calculated. The results show that in a confined space, the quasi-static pressures and equilibrium temperature of the aluminum powder in air are higher than in vacuum. In vacuum, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R3>R4>R2 and R3>R4>R1>R2, respectively. In air, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R2>R4>R3 and R1>R4>R2>R3, respectively. R4 (Al6+Al flake) and R3 (Al6+Al24) have relatively higher temperatures after detonation, which shows that the particle gradation method can enhance the reaction energy output of aluminum during the initial reaction stage of the explosion and increase the reaction ratio by 10.6% and 8.0%, respectively. In air, the reaction ratio of Al6 aluminum powder can reach as high as 78.16%, and the reaction ratio is slightly reduced after particle gradation. Finally, the reaction equations of the explosives in vacuum and in air were calculated by quantitative analysis of the explosion products, which provides a powerful basis for the study of RDX-based explosive reactions.     

高空平台通信系统中多波束天线辐射特性对系统性能的影响

高空平台通信系统中将采用多波束天线提供蜂窝覆盖，来提高系统容量。本文分析等波束宽度和等波束面积两种类型多波束天线辐射特性以及它们的几何模型，推导了载干比计算公式，通过仿真分析不同参数配置条件下多波束天线辐射特性对系统载干比性能的影响。研究表明等波束面积多波束天线比等波束宽度多波束天线具有更好的载干比分布特性。本文得出的结论对HAP通信系统规划具有重要的指导意义。     

高超声速变形飞行器翼面变形模式分析

为提高高超声速翼身组合式飞行器的射程,研究了采用不同翼面变形模式时,飞行器在马赫数3~8内的气动特性和翼面效率。针对典型的轴对称翼身组合式外形,采用Navier-Stokes方程进行数值模拟,对伸缩、变后掠和二维折叠三种变形模式下的外形在超声速及高超声速来流条件下进行模拟,并对升阻比、翼面单位面积升阻比和操稳特性进行分析。结果表明:在超声速及高超声速范围内,变后掠变形模式在宽速域内升阻比提高明显,同时具备优良的翼面效率及操稳特性,其在马赫数3~8范围内具有最优的综合性能。研究成果能对高超声速翼身组合式变形飞行器布局设计提供参考,具有一定的指导意义。     

吸附式储存液体燃料技术初探

利用吸油材料将液体燃料进行吸附储存是一种全新的储存方式，该储存方式与传统空腔储存液体的方式相比，在储存的安全性和可靠性上具有明显的优势。论文初次提出吸附式储存液体燃料技术（简称SFAM）的概念，并详细分析了SFAM技术下的吸放油性能、抑爆性能及环境适应性能的要求与实现机理，同时结合SFAM技术的使用特点和应用背景，对聚丙稀吸油棉、天然植物纤维、吸油树脂和聚氨酯泡沫等四类吸附材料进行了综合分析比较。     

高含硫气井井筒硫沉积的预测方法

近年川东气田的几口碳酸岩气井在开采过程中出现较为严重的硫沉积,有的甚至被硫堵塞停产,对这些气井的硫沉积进行精确的预测和有效的管理就显得至关重要.提出了一个新的解析模型,把硫的溶解度作为温度、压力及流态的函数,结合压力与温度的藕合,应用颗粒受力分析来预测含硫天然气开采中的气井井筒硫沉积,其预测结果与实际相符,可作为井下除硫处理、洗井作业、优化完井及开采速度等设计的基础.     

多层次信息融合技术在燃气轮机故障诊断中的应用

探讨了信息融合技术在燃气轮机故障诊断中的应用,构建出一种燃气轮机多层次信息融合故障诊断模型.在模型的数据融合层,采用了自适应加权融合算法,以最小化传感器测量不确定度为目标对同源测量数据进行了融合,其结果再经特征层进行故障特征的提取和融合,最终通过决策层给出诊断判定.数值实验结果证明,该故障模型能有效减小传感器测量不确定度对于诊断的不良影响,所得诊断结果的合理性和精度均得到了提高.     

瓦斯爆炸波自激励效应的实验研究

基于爆炸波的发展机理在气体爆炸防护技术研究中的重要性,通过实验对密闭通道中瓦斯爆炸波的传播特征及规律进行了研究。结果表明,瓦斯爆炸传播过程中,压力波对火焰波既有促进作用又有抑制作用,不同阶段的主导作用不同;而火焰波对压力波也会产生影响,不但会加强压力波的超压和振幅,而且会使压力波上升段压缩、下降段拉伸,最终可能发展为爆震波,对巷道内的建筑、设备造成极大的破坏。