Pre-processing for time domain image formation in SS-BSAR system

A pre-processing procedure is designed for a space-surface bistatic synthetic aperture radar (SS-BSAR) system when a time domain image formation algorithm is employed. Three crucial technical issues relating to the procedure are fully discussed. Firstly, unlike image formation algorithms operating in the frequency domain, a time domain algorithm requires the accurate global navigation satellite system (GNSS) time and position. This paper proposes acquisition of this information using a time-and-spatial transfer with precise ephemeris and interpolation. Secondly, synchronization errors and compensation methods in SS-BSAR are analyzed. Finally, taking the non-ideal factors in the echo and the compatibility of image formation algorithms into account, a matched filter based on the minimum delay is constructed. Experimental result using real data suggest the pre-processing is functioning properly.     

随机非对称耦合控制螺旋波和时空混沌

通过引入随机非对称耦合方法对螺旋波和时空混沌进行控制,数值模拟结果表明:在选择适当的控制参数下,螺旋波和时空混沌能被控制并最终达到稳定的靶波态,实现了对螺旋波和时空混沌的有效控制,在一定的耦合强度c和随机耦合概率p下,两个不同的系统之间存在相同步和完全同步现象,通过计算瞬时平均相位差△φ和泊松系数γ进一步验证了这一现象...     

浅谈广播电视数字通信系统的网同步

介绍了广播电视实现数字传输的特殊性,分析了网同步的必要性、方式及时钟类型,从时钟的工作模式、SDH(同步数字体系,Synchronous Digital Hierarchy)网同步的工作方式和SDH网元的定时方法等,指出只有实现数字通信网的网同步,才能实现数字节目的正常接收和交换。     

截谱模式方法与大气中的多重平衡现象

本文在介绍截谱模式方法的基础上,以强迫耗散的非线性准地转方程为例,用解析方法讨论了不同截断水平下模式方程对多重平衡态的影响。看出,截谱模式方法的最大成功之处在于揭示了大气中多重平衡现象。利用此法可将模式方程转化为耦合常微分方程组。特别是讨论平衡态时,归结为对代数方程的讨论。这就为揭示多重平衡现象和应用突变理论展示大气中突跳现象提供了可能。通过讨论也证实:随着截断水平的加大,平衡态分枝数随之增多,最终将进入“浑沌”状态。     

Kolmogorov生态系统的浑沌现象

本文在Kolmogorov生态系统的基础上,研究当b_(12)≠0,c_(12)≠1,且内禀增长率为r_1=f+ε(λ_1+λ_2cosωt)r_2=f+ε(λ_1+λ_2cosωt)受到ελ_3cosωt的强迫激励时所产生的浑沌现象。     

位同步提取中相位抖动、同步带宽与倒π误锁

本文论述了数字锁相环位同步提取的原理和防止倒π误锁的方法,在此基础上,对相位抖动、同步带宽的制约因素作了分析,提出了不同设计要求对调整步数的选取原则.实验结果与理论分析相吻合.     

一类锁相环路系统的混沌性态

本文研究一类较复杂的锁相环路系统,研究当参数λ_i 满足何种条件时该系统出现混沌解.     

A－NET机router间通信过程的模拟

在介绍了Ａ－ＮＥＴ计算机的ｒｏｕｔｅｒ部分的功能之后，主要叙述了利用ＵＮＩＸ进程管理和进程通信的功能对ｒｏｕｔｅｒ间通信过程的模拟。     

A Novel Digital Audio Watermarking Scheme in the Wavelet Domain

We present a novel quantization-based digital audio watermarking scheme in wavelet domain. By quantizing a host audio‘s wavelet coefficients (Integer Lifting Wavelet Transform ) and utilizing the characteristics of human auditory system ( HAS), the gray image is embedded using our watermarking method. Experimental results show that the proposed watermarking scheme is inaudible and robust against various signal processing such as noising adding, lossy compression, low pass filtering, re-sampling, and re-quantifying.     

Linearly Coupled Synchronization of the New Chaotic Systems

0IntroductionCahdaeoss[ 1h]a.sI bne e1n9 6i3nt ,en Lsiovreelnyz sftouudniedd t ihne t fhires tla scta ntohnrieceal d eact--tractor[2 ,3].In 1999 , Chen,et alfound another si milar buttopologically not equivalent chaotic attractor[4 ,5]. In 2002 ,Lu,et alfound a chaotic system[6],bearing the name of theLu system.In the second year , Chen and Lu introduced thenotion of generalized Lorenz canonical form(GLCF) , whichcontains the Lorenz system(τ∈(0,∞))and Chen system(τ∈(-1,0))as two ext…