【摘 要】
：
Increasing pulses Coherent processing interval (CPI) can effectively improve the location parameters estimation performance in passive localization.However,for
【机 构】
：
PLA Strategic Support Force Information Engineering University,Zhengzhou 450001,China
论文部分内容阅读
Increasing pulses Coherent processing interval (CPI) can effectively improve the location parameters estimation performance in passive localization.However,for a moving emitter transmitting pulses with Frequency agile and Pulse repetition frequency jittering (FA-PRFJ) in a CPI,there will exist random phase,uneven sampling and Range migration (RM),which deteriorates the estimation performance of location parameters.Aiming at long-time coherent localization parameters estimation for the above emitter,this paper proposes a joint Range difference (RD) and Range rate difference (RRD) estimation algorithm.Firstly,the signal model of a moving emitter transmitting FA-PRFJ signal is constructed,and the influence of the FA and PRFJ on coherent integration is analyzed.Secondly,the random phase induced by FA is eliminated by frequency symmetric autocorrelation function operation.Then,RD and RRD can be coherently estimated after RM correction via the modified scaled non-uniform fast Fourier transform.This method can be efficiently implemented by Fast Fourier transform (FFT),inverse FFT and FFT-based chirp-z transform without any searching operation.Simulation results demonstrate that the proposed method has a better antinoise capability with a much lower computational complexity compared with several representative methods.
其他文献
Flexible manifold embedding (FME) is a semi-supervised dimension reduction framework.It has been extended into feature selection by using different loss functio
The Satellite-based augmentation system(SBAS) is intended to provide real-time differential global navigation satellite system corrections with the high accurac
裂缝性礁灰岩底水稠油油藏具有内部断层及裂缝发育、非均质性强、原油黏度高等特点。针对该类油藏后期调整井投产后含水上升快,含水上升规律不明确,无法形成针对性堵水增产措施的问题,利用地质油藏资料和生产动态数据,在生产井含水类型划分及储层裂缝发育程度进行定量表征的基础上,基于改进的层次分析方法,开展了裂缝性礁灰岩底水稠油油藏含水上升主控因素分析研究。结果表明1)生产井含水类型可划分3类,一类井位于构造高部位,含水率随累产油量上升慢;二、三类井位于构造低部位及裂缝发育区,含水率随累产油量上升快。2)目标区块的西北部
双锥型旋流分离器的结构参数的改变对其分离效果会产生极大的影响,分析主要结构参数对除油率的影响规律对该设备的设计加工有着重要意义。通过三维建模软件和计算流体力学软件建立了公称直径为50 mm的双锥型水力旋流器经典模型,应用模拟对比的方法分析得出了溢流口直径Do、溢流管深入长度Ls、大锥角α这3个参数变化对压降和除油效率的影响,并利用递进优化的方式优选出最优结构参数。结果表明,当溢流口直径增加至25 mm时可将除油效率提高到94.19%,此时压降为53082.57 Pa;溢流管深入长度95 mm时分离效率为9
复杂山前带表层结构在纵、横向上变化剧烈,单炮能量弱,背景噪声发育,信噪比低,地震初至难以准确拾取。为了提高初至拾取精度及效率,针对单炮初至难以准确识别及初至拾取范围不明确等问题,开展波动方程正演、可控震源预处理及不同初至范围层析反演分析等方面工作。结果表明,波动方程正演模拟方法指导地震单炮的初至拾取,可以避免初至漏拾、错拾现象;可控震源单炮开展最小相位化和反褶积处理,近道初至识别率提高50%以上,可提高单炮初至信噪比;初至偏移距涵盖风化层及1 km左右的折射层时间范围即可满足层析反演精度需求。通过以上方法
大型轴承套圈受椭圆度的影响,在组装成轴承后,其径向游隙值产生了最大值与最小值的问题。目前大型轴承径向游隙是用平均法测量的,其测量点数很少,因而测量精度不够,同时反映不出来径向游隙最大值与最小值。本文设计了一种方法能够精确测量出径向游隙平均值,同时该方法也能够测量出径向游隙最大值与最小值,并找出径向游隙最大值、最小值的方向,从而满足工程实践当中径向游隙精确测量。
Many practical engineering problems can be abstracted as corresponding function optimization problems.During the last few decades,many bionic algorithms have be
针对轴承套圈小尺寸密封槽存在无法使用精密仪器直接测量的问题,提出使用复制胶泥结合影像测量仪对密封槽尺寸进行测量的方法。根据实际使用及测量数据表明该方法无需考虑密封槽尺寸及结构的影响,能够准确测量密封槽尺寸,提高加工质量及效率。
为了明确稠油在火烧油层高温氧化过程中的内在机理,应用热重、微商热重、差示扫描量热方法获取热分析基础数据,并应用Kissinger-Akahira-Sunose(KAS)等转化率法、Kissinger微分法和Coats-Redfern积分法进行高温氧化动力学参数分析。实验结果表明,应用KAS等转化率法、Kissinger微分法和Coats-Redfern积分法求取的稠油高温氧化反应动力学参数均在正常范围内,线性相关系数均在0.95以上。在高温反应阶段,油焦与氧气充分接触后燃烧以三维扩散为主。氧气浓度梯度是影