Power Absorption of High Frequency Electromagnetic Waves in a Partially Ionized Plasma Layer in Atmosphere Conditions

We have studied the absorption, reflection, and transmission of electromagnetic waves in an unmagnetized uniform plasma layer covering a metal surface in atmosphere conditions. Instead of the absorption of the electromagnetic wave propagating only once in previous work on the plasma layer, a general formula of total power absorption by the plasma layer with an infinite time of reflections between the atmosphere-plasma interface and the metal surface has been derived for the first time. Effects of plasma parameters, especially the dependence of the fraction of positive lons, negative ions and electrons in plasmas on the power absorption processes are discussed. The results show that the existence of negative ions significantly reduces the power absorption of the electromagnetic wave. Absorptions of electromagnetic waves are calculated.     

具有SMA驱动层的柔性蒙皮主动变形特性研究

制作了模块化的形状记忆合金丝夹层,提出形状记忆合金丝驱动夹层与蜂窝结构蒙皮的集成方法。对形状记忆合金丝进行加热,由于夹层内形状记忆合金丝排布方式的不同,可分别实现蜂窝蒙皮后掠与上反。研究嵌入驱动器夹层后的蜂窝结构蒙皮的主动变形能力。结果表明,在激励电流为3 A时,蜂窝蒙皮试件可上反5.1°或后掠8°。这种通过蒙皮自身产生的变形能够降低变体机翼蒙皮变形对驱动力的要求。     

输油控制阀测试系统的设计与开发

介绍了某型飞机输油控制阀测试系统的组成、工作原理及设计特点,并利用PLC、变频器和触摸屏技术设计了该装置的控制系统.结果表明该测试系统设计合理,达到了预期的设计目标.     

基于分组检查概率法的飞机液压系统故障原因分析

针对某新型飞机液压系统故障诊断中,液压系统附件数量众多,查找故障附件所需时间较长,严重影响飞机出动率。本文提出分组检查概率法分析飞机液压系统故障原因,将分组检查概率理论引入到飞机液压系统故障诊断领域,旨在缩短查找故障附件所需时间。实践结果表明,此方法能有效缩短飞机液压系统的排故时间,确保部队战训任务顺利完成,提高飞机出动率。     

强流脉冲电子束轰击产生表面熔坑的数值模拟研究

在纯A1强流脉冲电子束表面改性实验的基础上，通过数值计算方法对其温度场和熔化过程进行了模拟，给出了脉冲半高宽度为0．5μs、能量为3J／cm^2电子束轰击铝靶后：熔化深度约为2．5μm，与TEM的观察结果一致，熔化从0．4μs开始到1．6μs结束，最先完全熔化的位置约为1．4μm，亚表层首先熔化并且迅速膨胀(沉积的能量在最大射程的1／3处达到最大值)，体积膨胀力大约为275MPa，引起了熔体从亚表层通过表层向外喷发，熔体的喷发速度约为1330m／s，随后表面从内向外经历速率为10^9K／s的冷却过程，因而使得表面形成类似于火山坑状的“熔坑”。验证了SEM和TEM的实验结果。     

Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves,particularly in the sub-wavelength regime.To investigate the collisional effect in such plasmas,we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave.The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity.Results show that the collisions between the electrons and the neutral particles,as well as the incident angle and the plasma thickness,can disturb the transmission and reduce reflection significantly.     

A Resistive MHD Simulation of the Shear Flow Effects on the Structure of Reconnection Layer

By using a one-dimensional resistive magnetohydrodynamic （MHD） model, the Riemann problem is solved numerically for the structure of the reconnection layer under a sheared flow along the anti-parallel magnetic field components. The simulation is carried out for general cases with symmetric or asymmetric plasma densities and magnetic fields on the two sides of the initial current sheet, and cases with or without a guide magnetic field, as in various space and fusion plasmas. The generation of MHD discontinuities in the reconnection layer is discussed, including time-dependent intermediate shocks, intermediate shocks, slow shocks, slow expansion waves, and the contact discontinuity. It is shown that the structure of the reconnection layer is significantly affected by the presence of the shear flow. For an initial symmetric current sheet, the symmetry condition is altered due to the shear flow. For cases with an asymmetric initial current sheet, as at the Earth＇s magnetopause, the strengths of MHD discontinuities change significantly with the shear flow speed. Moreover, the general results for the reconnection layers in the outflow regions on either side of the X line are discussed systematically for the first time.     

飞机刹车控制阀的灵敏性分析

本文介绍了飞机刹车控制阀的工作原理和特点,分析了灵敏性低的原因。并在此基础上,提出了相应的解决措施．得出了一些有益的结论。     

农村危旧房改造存在的问题及对策

在当前全面落实科学发展观及构建和谐社会的总体要求下,农村在发展的过程中,由于自身相关因素的影响,致使部分农村用房出现了质量方面的问题。部分用房由于年久失修已经逐渐变成了危房。如果不及时进行处理,就会导致相关问题的出现,对于人财方面也会造成巨大的损失。因此为了促进农村的进一步发展,需要加快危房改造步伐,妥善解决农村困难户住房问题。为了做好相关的研究工作,本文主要对农村危房改造中需要遵循的准则、存在的问题,以及农村危房改造的对策进行了深入的分析。从而通过这种方式,促使农村危旧房改造工程的进一步开展。     

强流脉冲电子束纯铝表面改性过程的热力学模拟

针对强流脉冲电子束表面改性的特点,建立了相应的数学物理模型,以纯铝材表面改性实验为基础,计算了由强流脉冲电子束辐照材料表面所产生快速升降温与熔凝过程,对其中的熔化、蒸发、热应力波等现象分别进行了数值模拟。计算结果表明,熔化深度约在1-10μm,与实验结果接近;蒸发作用影响较小,汽化层厚度仅为纳米量级;热应力波的幅值约在0．1MPa量级,且与脉冲的能量密度大致成正比,但是对材料结构和性能有重要影响。