一种利用极化信息的HRRP-ATR方法

在研究了单极化条件下高分辨率距离像的目标识别后，给出一种利用目标全极化信息的投票识别方法。实验结果表明，该方法具有较高的识别率。     

超分辨率时延估计研究新进展

从多个具有相同已知波形且在到达时间上相隔很近的叠加回波信号中估计各个回波信号的幅度和到达时间，是一个比较困难的超分辨率时延估计问题。首先对这一问题的研究现状进行了综述，然后，介绍了笔者在此方面取得的最新研究进展，包括一类适用于不同应用背景的简单有效算法。所提出的新方法在许多领域中具有广泛的应用前景。     

基于TOPSIS算法的数据中继任务动态优先级设置方法

针对中继卫星系统资源分配中的数据中继任务优先级设置问题开展研究,提出动态优先级评价方法,打破现有基于预设固化时段完成冲突消解的任务规划模式.综合考虑用户、需求,以及任务重要性等因素,建立任务优先级两级评价指标体系.其中,刚性优先级用于度量资源申请的必要性,柔性优先级用于维护资源分配的公平性,同时促进资源使用的合理性.详细列举了各项指标的量化模型,给出了柔性指标综合计算算法.在实验分析中,通过大量数据统计,测试了所提方法的可行性和有效性.     

一种精度可调的速度测量系统的设计与实现

根据常用的频率采集方法,结合速度矢量信号的特点,提出了将速度矢量信号转换为不同相位的频率信号以实现速度矢量采集的设计思路,通过软硬件结合的方式实现速度采集系统.为提高系统的测试性,设计了自激励测试电路.为了解决速度变化带来的采样精度低问题,设计了采样时钟自动调整机制.经测试,采集结果准确,精度可调,可满足系统要求.     

轴流压气机近失速及旋转失速全通道数值模拟

为研究轴流压气机失速起始的动态过程,对某两级低速轴流压气机的第1级进行整环全通道模拟.结果表明:在近失速点流场中存在周向大尺度的速度波动,该波动与静子叶排首先出现的周向不均匀分布的叶背附面层分离密切相关,并且随着压气机进一步节流,波动幅值逐渐增大,最终诱发转子若干通道出现严重附面层分离,堵塞流道,压气机进入旋转失速.失速团完全发展后的转动频率与试验结果吻合较好.      

Navigation sensors and systems in GNSS degraded and denied environments

Position, velocity, and timing(PVT) signals from the Global Positioning System(GPS)are used throughout the world but the availability and reliability of these signals in all environments has become a subject of concern for both civilian and military applications. This presentation summarizes recent advances in navigation sensor technology, including GPS, inertial, and other navigation aids that address these concerns. Also addressed are developments in sensor integration technology with several examples described, including the Bluefin-21 system mechanization.     

脉冲超宽带信号测量性能分析

超宽带技术是一项新兴的无线通信技术,具有极其广阔的发展前景,但目前仅用于室内短距离通信,少见用于航天测控系统。为了将超宽带技术应用于测控系统中,以模糊函数为工具,对脉冲超宽带信号的测量性能进行分析。首先推导矩形脉冲串信号和载波调制矩形脉冲串信号的模糊函数,并对其模糊特性进行仿真分析。在此基础上,主要针对用于测控系统的伪码调制脉冲超宽带信号,利用其模糊函数分析其测距测速性能。结果表明:该超宽带信号具有良好的测距测速性能,其最大无模糊距离为1个伪码周期,最大无模糊多普勒频率为脉冲重复频率的倒数;单脉冲宽度越窄,其测距性能越好而测速性能越差。     

Virtual baseline method for Beidou attitude determination – An improved long-short baseline ambiguity resolution method

Ambiguity resolution (AR) is a critical step for successful attitude determination using carrier phase measurements of a satellite navigation system such as Beidou. This paper proposes an improved method for AR in support of Beidou attitude determination based on the concept of a “virtual baseline”. In the traditional long-short baseline method, the short baseline is limited to a length less than half of the carrier wave length of the Beidou signals. In the proposed method, a virtual short baseline is formed by differencing two collinear baselines. The AR equations for virtual short and long baselines are derived and the factors impacting the AR accuracy are analysed. Numerical simulation studies were carried out to evaluate the performance of the proposed AR method. The simulation results confirmed that the proposed method is an improvement over the traditional approach -- not only is it easier to deploy collinear antennas but also it keeps the capability of epoch-by-epoch AR, which makes it immune to cycle slips and there is no need for initialisation of ambiguity searching.     

高职学生英语歧义容忍度与写作成绩的相关性研究

对高职学生歧义容忍度总体水平以及歧义容忍度与写作成绩的关系运用访谈、问卷、测试等方法采集数据并对数据进行定量和定性分析。研究结果表明高职学生歧义容忍度水平较低；学生在写作方面的歧义容忍度水平最低，学生的写作成绩与歧义容忍度之间具有正相关的线性关系，但不具有显著性差异。本项研究对高职英语写作教学有重要的启示作用：帮助学生...     

One dimensional blood flow in a planetocentric orbit

All life on earth is accustomed to the presence of gravity. When gravity is altered, biological processes can go awry. It is of great importance to ensure safety during a spaceflight. Long term exposure to microgravity can trigger detrimental physiological responses in the human body. Fluid redistribution coupled with fluid loss is one of the effects. In particular, in microgravity blood volume is shifted towards the thorax and head. Sympathetic nervous system-induced vasoconstriction is needed to maintain arterial pressure, while venoconstriction limits venous pooling of blood prevents further reductions in venous return of blood to the heart. In this paper, we modify an existing one dimensional blood flow model with the inclusion of the hydrostatic pressure gradient that further depends on the gravitational field modified by the oblateness and rotation of the Earth. We find that the velocity of the blood flow V_B is inversely proportional to the blood specific volume d, also proportional to the oblateness harmonic coefficient J₂, the angular velocity of the Earth ω_E, and finally proportional to an arbitrary constant c. For c = −0.39073 and ξ_H = −0.5 mmHg, all orbits result to less blood flow velocities than that calculated on the surface of the Earth. From all considered orbits, elliptical polar orbit of eccentricity e = 0.2 exhibit the largest flow velocity V_B = 1.031 m/s, followed by the orbits of inclination i = 45°and 0°. The Earth’s oblateness and its rotation contribute a 0.7% difference to the blood flow velocity.