FDA-MIMO雷达稳健抗主瓣距离欺骗式干扰技术

频率分集阵(frequency diverse array, FDA)多输入多输出(multiple-input and multiple-output, MIMO)雷达可利用距离维自由度在发射-接收频率域内对欺骗式干扰进行抑制。但当存在目标导向矢量失配和协方差矩阵估计误差时,其抗干扰性能损失严重。针对该问题, 在FDA-MIMO雷达中提出了一种基于稳健波束形成的抗干扰方法。首先, 对剔除了残留噪声的Capon谱估计器在信号(或干扰)域内积分来构造期望信号(或干扰)导向矢量; 然后, 利用不同信号导向矢量间的正交性获得干扰功率并重构干扰加噪声协方差矩阵; 最后, 用更精确的导向矢量和重构矩阵计算自适应波束形成器的最优权值, 提高干扰抑制性能。仿真实验验证了所提方法的有效性。     

联合信道状态编码的基函数生成算法

针对远距离情况下基函数频谱失配导致的TDCS性能下降的问题,提出一种联合信道状态编码的远距离TDCS基函数生成算法。该算法通过对远距离收发两端的信道状态进行四进制合成编码,将联合信道划分为4种状态,根据频谱失配程度选择信道状态好的频点进行数据传输,并在解调前对接收信号进行滤波。理论分析表明,在相同情况下,使用联合信道状态编码机制的频谱利用率高于频谱交换机制的频谱利用率,从而有效避免收发两端放弃通信,更加接近TDCS的实际应用。仿真结果表明:该算法的抗干扰性能优于频谱交换机制,能够有效提高系统的频谱利用率,降低频谱失配对抗干扰性能的影响,扩展TDCS的应用范围。     

Evidence for Base Substitutions and Repair of DNA Mismatch Damage Induced by Low Energy N^＋ Ion Beam Implantation in E. coli

Ever since the low energy N^ ion beam has been accepted, the mutations of ionizing radia-tion are attributable mainly to avoidance of DNA damages repair. Evidences based on in vivo proof results are limited. Using the E. coli wild type and mutator strains, the mutant frequencies suggest that base substitutions in rpoB gene are induced by the N^ implantation. A highly con-served region is selected to get the direct evidence for base substitutions by sequence of the high fi-delity PCR amplification products in mutants. Most of the mutants (90.9%, 40/44) have at least one base substitution in the amplification region. The evidences for CG to TA (55 %, 22/40), AT to GC (20%, 8/40) and TA to CG (5%, 2/40) transitions are identified. The transversions are AT to TA ( 15 %, 6/40) and GC to CG (5 %, 2/40). It is suggested that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N^ implantation by analysis of the mutant frequencies of mutator strains.     

原位癌病变的基因改变和表达

阐述原位癌病变中调控细胞生长、分化的癌基因、抑癌基因、错配修复基因的突变、缺失和异常表达。说明原位癌中的这些分子水平的变化与浸润癌已无本质的区别，有的只是发生频率和强度的差别。     

Mismatch repair as an important source of new mutations in non-dividing cells

This paper describes a mechanism which permits somatic cells to generate random mutations in the complete absence of cell proliferation. Knowledge of the existence of this mechanism should provide us with the basis for a better understanding of a number of important biological phenomena, and in particular may help to explain the origins of many human cancers.     

Maximum Likelihood A Priori Knowledge Interpolation-Based Handset Mismatch Compensation for Robust Speaker Identification

Unseen handset mismatch is the major source of performance degradation in speaker identifica-tion in telecommunication environments.To alleviate the problem,a maximum likelihood a priori knowledge interpolation (ML-AKI)-based handset mismatch compensation approach is proposed.It first collects a set of handset characteristics of seen handsets to use as the a priori knowledge for representing the space of handsets.During evaluation the characteristics of an unknown test handset are optimally estimated by in-terpolation from the set of the a pdod knowledge.Experimental results on the HTIMIT database show that the ML-AKI method can improve the average speaker identification rate from 60.0% to 74.6% as compared with conventional maximum a posteriori-adapted Gaussian mixture models.The proposed ML-AKI method is a promising method for robust speaker identification.     

唾液腺多形性腺瘤及癌在多形性腺瘤中hMSH2、hMLH1蛋白的表达和意义

探讨错配修复基因hMSH2、hMLH1蛋自在唾液腺多形性腺瘤及癌在多形性腺瘤中的表达及意义。免疫组织化学SP法检测涎腺多形性腺瘤27例及癌在多形性腺瘤中蜡块标本22例,共49例标本hMSH2、hMLH1蛋白的表达情况。涎腺多形性腺瘤瘤旁正常组织、涎腺多形性腺瘤和癌在多形性腺瘤组织中hMSH2、hMLH1蛋白表达的阳、性率分别为28．57％和42．86％、96．3％和85．19％及90．91％和86．36％。hMSH2及hMLH1在涎腺多形性腺瘤和癌在多形性腺瘤组织中均表达上调。     

窄带主动噪声控制中频率不匹配应对方法实时仿真

非声学传感器的使用致使前馈窄带主动噪声控制(ANC)系统中往往存在频率不匹配(FM)。利用MATLAB/Simulink实时仿真功能,构建了针对前馈窄带ANC系统中FM应对方法的实时仿真平台。对一种改进的FM应对方法进行了深入的实时仿真研究,与传统的FM应对方法进行了比较,对其性能进行评估。仿真结果与分析表明,与传统FM应对方法相比,新方法能够应对较大的非平稳FM量,且具有较快的收敛速度。     

高效率前馈放大器单环抑制性能

国外有学者提出了一种延迟线失配法来提高前馈放大器的效率。为了更全面考察这种方法对于前馈放大器单环抑制性能,尤其是误差环路的抑制性能的影响,从幅度、相位误差以及延迟线失配3个方面进行了仔细全面地分析,并得出了相应的结论。     

多纵模半导体激光器的混沌同步研究

建立了多纵模外腔半导体激光器与单纵模半导体激光器的单向耦合系统理论模型,研究了不同纵模间的混沌同步及系统参数的影响.研究结果表明当内部参数完全匹配时该系统的同步性能较好,而且在内部参数不完全匹配的情况下也能保持较好的鲁棒性,说明在基于混沌的保密光通信中利用多纵模同步进行混沌复用通信是完全有可能的.