无源定位中基于小波变换的相位差去噪研究

实际工程中相位干涉仪的测量误差较大,造成相位差变化率定位算法的收敛速度较慢。利用小波阈值降噪法对相位差及其变化率信息进行平滑滤波,可以在相位差测量误差较大情况下进行快速高精度定位,而且观测间隔越短,抗噪性能越好,定位精度越高。仿真证明了算法的有效性。     

基于MIMO技术的卫星高速数据传输系统研究

多输入多输出（MIMO）系统作为提高频谱效率的一种有效方式,已经成为未来无线通信系统实现高速可靠数据传输的突破性技术之一,受到国际众多研究机构的普遍关注。文章通过研究MIMO信道模型、信道容量、卫星信道特征,构建了全新高速数传系统模型,解决了卫星大容量数据实时传输和频带限制之间的矛盾。     

Longitudinal distribution of thermospheric densities and ionization rates in the upper atmosphere of Mars at mid-latitude using MGS ACC data

The Accelerometer Experiment (ACC) onboard Mars Global Surveyor (MGS) measured 1600 density profiles in the upper atmosphere of Mars during aerobraking. These measurements reveal large-scale and small-scale structure in the thermosphere of Mars. Here, the measurements of mass density for 115 orbits (#P0670–P0789) from November 1 to 30, 1998, under spring equinox and medium solar activity conditions (average F_10.7 ∼ 137) during phase 2 of the aerobraking in the thermosphere of Mars at different altitudes and longitudes are presented for northern mid-latitude (17–42°N) in the dayside atmosphere using ACC onboard MGS. From these mass densities, the neutral densities of different gases are derived from their mixing ratios. Using these neutral densities, the longitudinal distribution of photoionization rates and photoelectron impact ionization rates are calculated at wavelength range 1–102.57 nm due to EUV and soft X-ray radiation under photochemical controlled region using Analytical Yield Spectrum approach (AYS). These conditions are appropriate for MGS Phase 2 aerobraking period from which the accelerometer data is used. Under the photochemical equilibrium condition, the electron density near the peak varies as the square root of the total peak ionization rate. Using this fact, an attempt is being made to estimate the mean primary and secondary peak electron density by averaging the longitudinal variations of total peak ionization rates in the northern mid-latitude (17–42°N) ionosphere of Mars, as there is no radio science measurement at this latitude region by MGS.     

亚燃冲压发动机燃烧室燃油浓度分布预测

基于Fluent两相反应流场计算平台，采用涡耗散概念模型，对典型亚燃冲压发动机燃烧室的两相反应流场进行三维数值模拟计算。重点研究温度场影响下的燃油气相分布，计算给出气相燃油在火焰稳定装置前后以及内部的分布，得到燃油在亚燃冲压发动机燃烧室内分布的一般规律。计算发现，稳定装置内部及近后方燃油分布较富，到达火焰峰以后，燃油浓度急剧下降。计算预测径向蒸发管后壁面与最外环蒸发管内的燃油富集，而中间环蒸发管燃油分布较贫，计算结果与燃烧试验结果一致。     

Efficient computation of energy release rates for delaminated beam structures

The often encountered problem of mode partitioning for delaminated, isotropic beam structures is addressed. For the sake of efficiency, solutions that do not require complex continuum solutions – in practise mostly obtained by the finite element method – are examined. Three approaches that meet the postulated efficiency are reviewed and compared. While one method fits consistently into the concept of linear-elastic fracture mechanics, the remaining two deduce mode partitioning hypotheses solely from kinematic quantities of beam theory. The results obtained through these hypotheses are then compared to continuum-based solutions. The latter are generated by the finite element method and are validated by analytical solutions as applicable. Furthermore, mode partitioning solutions for beams, loaded in transverse shear, are given with excellent accuracy. Finally, the conditions for which the different methods comply with or substantially deviate from each other are discussed.     

利率模型的动态估计

利率模型主要用来描述利率的动态行为，迄今为止大多数利率模型都是在CKLS框架之下进行的实证研究。这一模型主要表现为两点不足：一是模型漂移假定为利率水平的线性形式，二是短期利率的波动性假定为利率水平的函数，这两个假定都与实际不符，直接在这一框架下描述我国利率的变动显然是不合适的。文章尝试提出一个新的利率模型，这一模型既考虑了利率变动的非线性特征，又考虑了波动率，结果表明该模型能够较好地描述我国利率变动特征，对我国市场利率的动态行为具有较好的解释力。     

一种新型燃速催化剂的作用效果研究

合成了一种新型二茂铁化合物—1,1—双(三甲基硅氧乙基)二茂铁,并研究了这种化合物对AP/HTPB复合推进剂燃烧性能、力学性能以及工艺性能的影响。实验结果表明,这种化合物具有改善推进剂燃烧性能和力学性能的双重作用。     

长空无人机系列燃油系统原理性能分析研究

本文主要介绍长空无人机系列中,各型无人机中、高空型、低空型、高机动型燃油系统在结构原理和性能方面的特点,并对它们进行了分析比较。     

过渡金属氧化物催化部位的实验研究

采用热分析技术和单幅近距摄影实验,考察了过渡金属氧化物(TMO)对HTPB推进剂凝聚相反应和气相反应的催化作用,讨论了TMO的主要催化部位。     

直升机发动机燃油泵自吸油地面模拟试验中用正、负压模拟燃油过载的研究

本文推导了在势函数π=fz的有势力场中一维绝热定常流的能量方程,并对该方程进行分析,提出了在直升机燃油系统地面模拟试验中用正、负压模拟从油箱到发动机吸油口管路中燃油的过载来进行在各种飞行高度、各种供油状态下的发动机燃油泵自吸油地面模拟试验。