固体火箭发动机试验模态分析技术研究

将固体火箭发动机划分为144个自由度，采用锤击法，单点激励多点响应（SIMO）对其在4种工况下进行了频率响应的测量，应用了多种方法进行模态参数识别和数据拟合，并对其结果进行比较，获得了发动机在各工况1kHz以内的各阶固有频率、振型和阻尼，并对试验模态分析技术在固体火箭发动机试验中的应用进行了研究。     

一个新的蠕变寿命估算公式的推出

本文从一些经典公式出发,推导出新的寿命公式。另外,通过引入蠕变损伤特征参量的概念还导出类似的另一个蠕变寿命估算公式。所推导出两个公式在16MnR材料中得到较为成功的应用。     

轴对称跨音速流中无激波超音速区的设计

本文直接从音速线出发计算了一个旋成体跨音速绕流超音速泡中的特征线网。提出了从音速线开拓到一条超音速线的方法,计算了无旋轴对称流的特征线网,发现其特点是不能跨越对称轴线,并对其原因作了初步的讨论。本文的计算结果可应用于物面修形。     

The fundamental parameters of the central stars of eight WR ring nebulae

We describe work that has recently been completed on deriving the fundamental parameters of eight WR stars through the photoionization modelling of their surrounding nebulae using non-LTE WR flux distributions. The resulting effective temperatures range from 57 000–71 000 K for the WN4-5 stars and <30 000–42 000 K for the WN6-8 stars. The derived stellar parameters are compared with those obtained from stellar emission line modelling. We find good agreement for the hot early WN stars, indicating that the non-LTE WR flux distributions have essentially the correct shape in the crucial far-UV region. We find lower temperatures for the four cooler late WN stars, particularly for the two WN6 stars. For the nebulae surrounding these stars, we find that the model flux distributions produce too much nebular ionization. We suggest that these discrepancies arise because of the lack of line-blanketing in the WR atmospheres. For the WO1 central star of G2.4+1.4, with strong nebular He II 4686 A emission, we derive a temperature of 105 000 K, somewhat less than previous estimates. The positions of our eight WR stars on the H-R diagram are compared with the evolutionary tracks of Maeder (1990) for solar metallicity. In common with previous workers, we find that our derived luminosities are too low, giving an initial mass range of 25–40 M, below that expected for the majority of WR stars.     

用非线性模型分析气动液阀的启动特性

对气动液阀的启动过程建立了非线性数学模型,分析了尺寸参数和推进剂进、出口压力对该阀的启动特性的影响。计算结果表明：在保证必要的工作寿命的前提下,适当地增大控制腔气孔的直径或增大靠近控制腔的活塞端面直径,降低推进剂进口和出口的压力有利于提高该阀的响应能力。     

Study on the Microstructure and Dielectric Properties of Barium Strontium Titanate Thin Films Prepared by Sol-gel Method

Sr05Ba0.5-xBixTiO3 （BST） thin films were fabricated on a Pt/SiO2/Si substrate by the sol-gel method. Then follows an investigation of the influeoces of bismuth （Bi） on the microstructures and the dielectric properties of Sr0.5Ba0.5-xBixTiO3 （BST） thin films. The microstructures of the BST thin films were examined by the XRD and the TEM techniques. Tetragonal perovskite crystal grains were observed in BST thin films. Increasing Bi^3＋ doping ration in BST will lead to decrease of the grain size. It is found that Bi^3＋ doping decreases the dielectric loss and improves the frequency dispersion of the BST thin films. Not only is compressed the peak of temperature-dependence of dielectric constant of Bi^3＋-doped BST thin films but also moves into the low-temperature region. Moreover, the average Curie tem- perature decreases gradually with the Bi^3＋ contents increasing.     

流量定位喷注器的静态与瞬态特性

本文分析了流量定位喷注器的工作原理及静态与瞬态特性,给出了实现等压降工作特性的基本准则.     

利用非交错对称矩阵构造Cartesian认证码

利用特征为2的有限域上非交错对称矩阵构造了一个Cartesian认证码，并计算出其参数。进而，假定编码规则按照均匀的概率分布所选取，计算出了该码被模仿攻击成功的最大概率只和被替换攻击成功的最大概率Ps。     

空气雾化喷嘴内液膜对雾化性能的作用

本文综合归纳数年来对空气雾化喷嘴内液膜厚度特性,液膜表面扰动波动态特性以及这些特性与雾化特性间的关系等方面的研究结果.着重指出在喷嘴唇口附近没有周期性的液流堆积现象,并且指出唇口液流堆积雾化论的问题所在.     

粘弹性结构振动特性分析的摄动求解技术

 本文根据粘弹性结构的特点,对其振动特性进行简化分析,构造了这类结构振动特性分析的摄动求解方法,给出了低阶摄动求解公式。还讨论了零阶摄动有重特征值时的求解。