基于EMD的高频地波雷达抑制射频干扰研究

提出了一种新的抑制射频干扰(RFI)方法,通过短时傅里叶变换找到干扰的时间位置,应用经验模态分解(EMD)方法,去除满足一定频域条件的射频干扰,达到在抑制射频干扰的同时,最大程度上保留有用信号的目的.实测数据分析表明:该方法在不损失有用信号的基础上有效抑制了射频干扰,且处理速度快,满足高频地波雷达(HFGW)实时工作要求.     

SC-IFDMA系统中的低复杂度载波频偏抵消算法

分析了单载波交织频分多址(SC-IFDMA)系统中载波频偏对系统性能的影响,推导了由于载波频偏而引起的信噪比损失公式,提出了一种新的低复杂度的线性时域频偏抵消(TD-CC)方法,并将TD-CC方法与串型干扰抵消技术相结合,提出了一种联合频偏抵消、频域均衡的串型多用户联合检测(TD-CC-SIC)方法.仿真结果表明,TD-CC和TD-CC-SIC方法较传统频偏抵消方法有更好的性能.     

一种新的混合多径干扰抵消方法

在CDMA上行链路中,由于信号的异步传输和多径传播,会引起多址干扰和多径干扰,使得传统的RAKE接收机性能变差．并行干扰抵消和串行干扰抵消可在一定程度上抑止干扰,但并行干扰抵消抗远近效应能力较差,串行干扰抵消会引入较大的处理延时．提出了一种新的混合干扰抵消接收机结构,具有低复杂度,低延时,抗远近效应等优点,可以有效克服多址干扰和多径干扰,性能明显优于上述两种干扰抵消方法．     

多码CDMA系统中联合软并行干扰抵消与Turbo译码方法研究

针对多码CDMA系统提出了一种联合软部分并行干扰抵消与Turbo译码估计方法。该方法首先通过线性最小均方误差均衡器(LMMSE)在切普级对接收到的多码CDMA信号进行均衡，然后使用Turbo译码后得到的软信息对干扰信号进行重构，最后通过并行干扰抵消(PIC)去除多码干扰(MCI)。仿真结果表明，经过多次迭代后，相比传统的部分并行干扰抵消，该方法可显著降低多码CDMA系统的误比特率。笔者同时还给出了切普级均衡、车速和PIC次数对多码CDMA系统性能的影响。     

利用CEMD抑制高频地波雷达射频干扰的工程应用

为了抑制高频地波雷达(high frequency ground wave radar, HFGWR)射频干扰(radio frequency interference,RFI),本文提出了复数经验模态分解(CEMD)方法,在抑制射频干扰的同时,最大程度上保留有用信号。通过模拟及实测数据的验证分析：该方法在不损失有用信号的基础上有效抑制了射频干扰,且处理速度快,满足高频地波雷达实时工作要求。     

利用复数经验模态分解抑制高频地波雷达射频干扰的工程应用

为了抑制高频地波雷达(high frequency ground wave radar,HFGWR)射频干扰(radio frequency interference,RFI),提出了复数经验模态分解(CEMD)方法,在抑制射频干扰的同时,最大程度上保留有用信号。通过模拟及实测数据的验证分析,该方法在不损失有用信号的基础上有效抑制了射频干扰,且处理速度快,满足高频地波雷达实时工作要求。     

一种改进的自适应并行干扰抵消算法

分析了LMS算法用于部分并行干扰抵消器(PIC)的不足，提出了一种采用变步长LMS自适应算法的改进方案。该方案利用变步长自适应算法收敛速度快且具有较小稳态误差的特点，使计算出来的部分干扰抵消系数更可靠。实验结果表明，本文提出的改进方案，在误码率性能方面优于传统PIC方法。     

一种循环谱域GPS卫星导航信号抗干扰方法

针对弱GPS信号受到的时频重叠复杂强干扰,采用信号抵消的思想,提出了一种在循环谱域消除干扰的方法.首先通过循环谱分析获得强干扰信号的循环频率参数;然后利用自适应频移(frequency shift, FRESH)滤波器与所得干扰信号的循环频率,得到具体的强干扰重构与抵消的频移滤波处理过程;最后采用LMS(least mean square)自适应算法对频移滤波进行实际实现,即可完成对强干扰的快速去除.通过对不同干扰场景下分离出的GPS信号跟踪捕获性能仿真,验证了所提方法的有效性.     

基于Karhunen-Loeve变换的GPS弱射频干扰检测

干扰是无线电通信系统最大的威胁之一,干扰检测对于全球导航卫星系统(Global Navigation Satellite System,GNSS)信号非常重要。为了检测GPS(Global Positioning System)信号中射频干扰,文章提出了一种新型的基于Karhunen-Loeve变换(KLT)射频干扰(RFI)的检测算法。通过GPS信号模拟器生成GPS L1信号,并在射频前端叠加射频干扰;再利用KLT对其数字中频信号进行分析和处理,得到相关矩阵(Toeplitz矩阵)的特征值,通过特征值重建干扰信号。经过仿真验证,该算法能够成功地检测出干扰信号,包括微弱的干扰信号。     

基于自适应网络模糊推理系统的噪声抵消

对自适应网络模糊推理系统(ANFIS)在噪声抵消中的应用进行了研究，说明了ANFIS的结构和使用ANFIS进行噪声抵消的原理，对窄带干扰的滤除和噪声中的信号提取两种情况进行了仿真，并对ANFIS和LMS(小均方误差准则)两种算法进行了对比研究，结果表明，利用ANFIS进行噪声抵消要优于LMS。     

基于压缩感知的时域抗射频干扰方法

射频干扰是高频地波雷达中一种不可避免的干扰,在海态探测应用中,会对海洋回波信息的提取造成极大困难。基于射频干扰在原始时域数据上的短时性特征,提出了基于压缩感知的时域抗射频干扰方法。该方法利用少量的无干扰采样数据即可对干扰数据段的海洋回波进行估计,以完成射频干扰抑制。经过仿真和实测数据的检验,射频干扰被完全抑制且海洋回波保持完好,表明该方法对射频干扰有良好的抑制效果。     

Anti-interference method for HF radars by transmitting phase-modulated chirps

Radio frequency interference （RFI） is a major problem in high-frequency （HF） radars. Conventional filtering-involved RFI suppression methods may introduce distortions to the target signals of interest and often demand extra hardware costs. In this paper, a novel method for RFI suppression by using linearly or randomly phase-modulated （PM） chirps is proposed, which enables independent analyses of the target signal and the RFI. Furthermore, the directions of arrival （DOA） of the interference are used as constraints to ensure a better DOA estimation of the target. The effectiveness of the method is demonstrated by numerical simulation results. The method can greatly improve the anti-interference capabilities of HF radars and is extremely applicable in the portable and low-cost radar systems.     

基于LMS自适应噪声对消法的激光液位测量信号波动抑制研究

针对激光液位检测中的信号波动问题,提出了一种采用LMS自适应噪声对消法抑制噪声的信号滤波方法,该方法采用数字高通滤波器获取自适应噪声对消器参考通道的信号。论述了自适应滤波器噪声对消的工作原理、LMS算法以及Butterworth数字高通IIR滤波器的设计方法,给出了整个噪声对消系统的原理图。仿真和实验结果表明,该噪声对消法在保证实际测量信号相位不变的情况下对液位测量信号的波动影响具有明显的消除和抑制作用。     

过程检测控制系统中的快速自适应滤波

本文分析了LMS噪声抵消法的局限性,在讨论过程检测控制系统中信号和噪声一般模型的基础上,针对强噪声情况提出了一种基于建立相关模型的快速自适应滤波(FAF)。它是利用快速横向滤波(FTF)自适应算法对相关模型进行仿模而实现的。仿真与试验表明,本文所提出的方法较LMS法优越,适于过程检测控制系统采用。     

Adaptive Radio Frequency Interference Mitigation for HF Surface Wave Radar

The paper analyses the characteristics of radio frequency interference （RFI） in HF surface wave radar （HFSWR） which adopts the linear frequency modulated interrupted continuous wave （FMICW）. RFI will influence all the range cells including all the positive frequency and negative frequency, and the negative frequency range cells contain only the interference information. Based on the above characteristics, we introduce and analyze a new adaptive interference mitigation beamforming algorithm using the negative frequency range cells samples to estimate the interference covariance matrix. Experimental results confirm that this general and robust algorithm can achieve effective RFI suppression using the data recorded by the HFSWR, located near Zhoushan in Zhejiang China.     

Design Optimization of RFI Parameters by Manufacturing T-shaped Composite Panel

The aim of this project is to develop a novel approach for optimizing design resin film infusion (RFI) processing parameters by manufacturing T-shaped composite panel. The dimensional accuracy was selected as the objective function. By investigating the rheological properties of resin film, the compaction behavior of fiber preform and characteristics of RFI process, an optimal mathematical model was established, it was found that the numerical results obtained from the RFICOMP program package have good consistency with the experimental results, and this optimization procedure can be applied to other composites manufacture processes.?AKeywords：Composites, Resin Film Infusion, Design Optimization, Accuracy.     

Developing a genome-wide selection model for genetic improvement of residual feed intake and carcass merit in a beef cattle breeding program

Residual feed intake (RFI) and carcass merit (CM) are both complex traits emerging as critical targets for beef genetic improvement.RFI and CM traits are difficult and expensive to measure and genetic improvement for these traits through traditional selection methods is not very effective.Therefore,genome-wide selection using DNA markers may be a potential alternative for genetic improvement of these traits.In this study,the efficiency of a genome-wide selection model for genetic improvement of RFI and CM was assessed.The Illumina Bovine50K bead chip was used to genotype 922 beef cattle from the Kinsella Beef Research Ranch of the University of Alberta.A Bayes model and multiple marker regression using a stepwise method were used to conduct the association test.The number of significant SNP markers for carcass weight (CWT),carcass back fat (BF),carcass rib eye area (REA),carcass grade fat (GDF),lean meat yield (LMY),and residual feed intake (RFI) were 75,54,67,57,44 and 50,respectively.Bi-variate analysis of marker scores and phenotypes for all traits were made using DMU Software.The genetic parameter for each trait was estimated.The genetic correlations of marker score and phenotype for CWT,BF,REA,GDF,LMY and RFI were 0.75,0.69,0.87,0.77,0.78,and 0.85,respectively.The average prediction accuracies of phenotypic EBV for the six traits were increased by 0.05,0.16,0.24,0.23,0.17 and 0.19,respectively.The results of this study indicated that the two-trait marker-assisted evaluation model used was a suitable alternative of genetic evaluation for these traits in beef cattle.     

环状DNApUC118与配体小檗碱相互作用的荧光特征

采用荧光光谱法对环状双譬超螺旋DNA质粒pUC118与小檗碱(Berberine)相互作用方式进行了初步探讨，在pH=3.20的甘氨酸一盐酸缓冲液中，二者相互作用的荧光强度达到最大；二者相互作用达到稳态时，一个小檗碱分子约结合七个碱基对；二者的结合除嵌插方式外，还存在非特异的静电作用；不同的荧光猝灭荆对二者相互作用荧光强度的猝灭程度是不同的，游离的水合状态小檗碱最容易被[Fe(CN)6]^-4猝灭。     

恶劣信道下的OFDM公共相位误差消除方法

为了精确消除相位误差影响,获得良好系统性能,提出了一种新的OFDM(Orthogonal Frequency Division Multiplexing)公共相位误差消除方法,该方法给出了在频率同步和信道均衡两级联合完成公共相位误差校正的结构,利用全导频,提出新的公共相位误差估计算法.理论分析和计算机仿真表明,两级联合校正结构非常适合OFDM系统中的公共相位误差校正,全导频公共相位误差估计算法可以获得优于传统方法的估计性能,特别在恶劣信道条件下,提出的全导频估计算法非常适用.