Scheme of adaptive polarization filtering based on Kalman model

1.INTRODUCTIONIn modern high technology war,the electroniccounter measures(ECM)and precise guidance tech-nology are rapidly developed and becoming the re-search hotspot of militarysciencefor all the countries.The guidance missiles are the main weapons andhigher anti-jamming ability and guidance precision arerequired for guidance radar.For the active mono-pulse guidance radar,the angle information of thetarget is obtained by usingthe angle measured methodof amplitude sum/difference or pha…     

快速跳频PLL中杂散抑制比的最佳设计值

系统地研究了快速跳频PLL中杂散来源,给出了环路杂散模型,定义了杂散抑制比。定性分析了MF SK FH通信系统检测误码率Pe与杂散抑制比λ之间的关系,并通过计算机辅助分析,定量计算出误码率与杂散抑制比的关系曲线。实验结果表明,MFSK FH通信系统中存在一个杂散抑制比的最佳设计值,约为-50dB,它为快速跳频PLL的优化设计提供了参考依据。     

三阶累积量在可控震源勘探信号处理中的应用

可控震源浅层地震勘探接收信号受环境噪声污染严重。为了提高压制噪声的能力,尝试用三阶累积量为数学工具,求出发射信号与接收信号的三阶互累积量,并把互累积量用发射信号自累积量进行线性分解。根据分解系数序列来检测接收信号中各反射信号分量的存在,并估计各反射信号分量的时间延迟。数值实验结果表明,该方法能从信噪比为0dB的接收信号中准确检测出反射信号分量并估计其时间延迟。鉴于高阶累积量具有屏蔽高斯噪声的优点,其用于可控震源地震勘探信号处理的效果比传统的相关方法要好。     

变换域通信系统的仿真分析

研究变换域通信系统(TDCS)独特的频谱利用方法,对其净化干扰的能力进行分析.在阐述变换域通信技术特点和基本原理的基础上,设计其实现框图,并利用MATLAB对变换域通信系统的干扰抑制能力进行仿真.仿真结果表明,变换域通信系统能自适应躲避干扰,具有较强的干扰抑制能力,与OFDM,MC-CDMA相比具有更好的误码性能.     

基于模糊熵和结构特征的边缘检测方法

为了使检测的图像边缘结核定位好,并且产生边续的精细边缘,同时能有效滤除边缘图像中的噪声,提出一种基于模糊熵与边缘结构特征相结合的新的图像边缘检测方法。该方法首先将图像的灰度值特征空间转换为模糊熵特征空间,计算出每个像素在模糊熵特征空间的相异测度,结合3×3 邻域内的12种有效的边缘结构,提取图像中每个像素的结构信息测度图像阵列和方向信息测度图像阵列,然后对结构信息测度图像阵列和方向信息测度图像阵列实施非极大抑制,确定最终的边缘像素图像。实验结果表明该方法所检测出的图像边缘细节丰富,单像素宽,定位准确,有较好的抗噪性。     

Built-up Effect of Core Material for Microencapsulated Flame Retardant Containing Dimethyl Methyl Phosphate

The flame retardants containing organophosphorus compounds have extensively been used inthe flame retarding of polymer materials.Among others,dimethyl methyl phosphate (DMMP) was applied in flame retarding of polyurethane owmg to its so much merit.However,the water-soluble property of DMMP restricted its application in textile fabric.The flame retardtag systemcontainirm DMMP will be microencapsulated to form a novel flame retardant that could be used in textiles.We have studied the builtup effect of DMMP with some inorganic compounds to improve the afterflame and afterglow suppression in the flame retarding system.The experimeatal data indicated that inorganic compounds containing various non-metal elements P,N,B and metal ions Mg2 ,Al3 ,Ca2 ,Zn2 ,Cu2 ,Mn4 could be applied in flame retarding systems as additives to effectively suppress afterflame or afterglow.     

基波磁势自平衡串并联混合有源电力滤波器

研究了基波磁势自平衡串并联混合有源电力滤波器.其串联在系统和谐波负载之间的零磁通变流器可自动实现对基波呈现低阻抗,对谐波呈现高阻抗,并可实时方便地检测出剩余谐波电流流过变流器时产生的谐波电压降.通过逆变器产生一个与检测到的谐波电压成正比的谐波电压源,并通过耦合变压器与无源滤波器串联之后再并联接入电网,从而更好地减少流入系统的谐波电流.实验结果证明了结论的正确性.     

若尔盖地区地表油气化探的影响因素及消除方法

地表油气化探影响因素众多,不同地区主导因素也不尽相同.通过对若尔盖地区近地表油气化探原始数据特征分析,认为该复杂地貌区的化探样品分析数据差异较大,其干扰因素主要源于地形地貌和样品岩性等差异.为了研究不同地形地貌特征可能对化探指标的影响,利用地表遥感图像解译对研究区进行了地球化学景观分类,分别统计背景值,以消除不同景观条件下对化探成果的干扰影响;为了抑制不同岩性造成的干扰,运用数理统计方法,找出区域总样品数中比例大、岩性相同的原始分析数据作为标准,对全区样品进行分类,利用比值法进行校正.最后通过综合异常分析,给出了3个可能的油气远景区.     

Effects of water mist addition on kerosene pool fire

The use of water mist to extinguish fire is a problem of particular interest since the banning of halogen-based agents for environmental reasons. This interest is reflected in the large number of researches performed on the main fire-extinguishing mechanisms of water mist： heat extraction, oxygen displacement and attenuation of heat fluxes. In contrast, there are still little known about the chemical and some other aspects of water mist addition on the pool fire. In this paper, a phenomenological study was conducted of the effect of water mist addition on the kerosene pool fire through the measurement of the heat release rate, CO, CO2 and O2 species concentration in combustion. The experimental results show that there is a significant enhancement effect at the beginning stage of water mist addition. Then, the flame size was decreased abruptly. By physical suppression effect combined with chemical effect, the experiments＇ results are explained especially. The study of effects of water mist on pool fire will be useful for optimizing designation of water mist fire-suppression system, improving the fire suppression efficiency and extending their application field.     

基于预先补偿和全状态反馈控制的车-轨耦合振动抑制

以高速磁浮列车为研究对象,探讨了弹性轨道下的车-轨耦合振动问题。建立了能反映实际问题的车-轨耦合最小悬浮单元模型,并进行了开环系统稳定性和耦合振动机理分析。以弥补比例-积分-微分（PID）控制器有效信息利用不足为出发点,设计了基于预先补偿的全状态反馈控制器。通过仿真分析了反馈增益矩阵对系统跟踪性能和振动抑制能力的影响,提出了适当降低对悬浮间隙的要求换取振动抑制能力提升的思路。进一步分析了反馈系数对悬浮系统性能的影响规律,基于此得到了优化的预先补偿和全状态反馈控制框架。最后,通过实验验证了基于预先补偿的全状态反馈控制对抑制车-轨弹性耦合振动的有效性。