地中海果蝇鸣声特征分析

利用计算机鸣声分析技术,对地中海果蝇鸣声的声学特征进行了全面分析,探讨了果蝇鸣声特征及其生物学意义,并将果蝇鸣声区分为3个部分．结果表明,地中海果蝇召唤歌为正弦波,IPI（两相邻脉冲的时间间隔）均值为2．9ms,基频约为366Hz;而其求爱歌由脉冲串组成,每个脉冲串大约持续0．1s,求爱歌的IPI均值为3．2ms,基频约为146Hz．此分析为果蝇鸣声的系统研究提供了基础数据．     

基于频域特性的工况变化系统的PI参数整定

控制系统的闭环特性在频域中是以幅值裕量和相位裕量表征的,由于被控系统在实际运行中工况条件存在不确定性,系统的性能往往达不到设计要求.提出一种基于继电反馈测试的方法,在线测量实时控制系统的两个频域指标,并在此基础上进行PI控制器的参数调整,以保持系统的闭环性能.仿真结果表明,该方法是有效的.     

PTW整环的刻画

引入了PTW整环的概念,刻画了PTW整环的局部化性质,然后对PTW整环的拉回图进行了研究,证明了若RDTF是强Milnor方图,则w-dim（R）=max{htτM＋w-dim（D）,w-dim（T）},最后通过例子说明了PTW整环不是TW整环．     

小波建模法在混凝土材料介电常数时域测量中的应用研究

材料电磁参数的测量方法主要分为时域和频域两种。在时域测量时，需要通过FFT才能求得介电常数的频谱特性，而实际测得的波形往往存在多次反射，给求取一个纯净的反射波进行频谱分析带来不便。针对这一问题，提出了采用小波建模法对脉冲时域反射波形进行处理，给出了FFT法和小波建模法分别对模拟和实测波形处理结果的比较。结果显示小波建模法可以较好地区分时域反射波形中的反射信号，并能够从时域波形有效地提取介电常数随频率的变化规律。     

Prediction of sites under adaptive evolution in flavin-containing monooxygenases: Selection pattern revisited

Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food.     

基于三维空间域统计信道模型的空时特性

为了研究信号在三维空间域信道模型中的空时统计特性,建立了一种三维统计信道模型,其散射椭圆半球体的中心在移动台(MS),适用于设置低MS天线、高基站(BS)天线且重要散射体分布在移动台附近的室外宏蜂窝通信环境中。假设模型的发射信号服从均匀分布,给出了到达角度(AOA)和到达时延(TOA)概率密度的分析算法,能够估计多径衰落信道的重要空时特性,在方位角和仰角平面同时描述波达信号分别在BS和MS处的分布特性。理论分析和数值仿真结果与三维散射模型结果对比表明,本模型的信道参数估计符合理论与经验结果,更加适应各种室外移动通信环境,拓展了三维统计信道模型的分析和研究。     

A novel numerical method for infinite domain potential problems

The infinite domain potential problems arise in many branches of scientific and engineering fields, which by now still pose a great challenge to scientific computing community.This study proposes a novel meshless singular boundary method (SBM) to solve infinite domain potential problems.The SBM is mathematically simple, easy-to-program, meshless and integration-free.To guar-antee the uniqueness of numerical solutions, this article adds a constant term into the SBM approximate representation.The effi-ciency ...     

宽带直接处理方法的性能分析

首先建立了宽带阵列信号处理的模型,在此基础上,主要分析了CSM,BASS-ALE,以及FDM宽带高分辨方位估计算法.进行了计算机仿真试验,在理论上分析和比较了三种方法的性能,验证了宽带波达方向(DOA)估计算法的有效性.仿真结果表明,与CSM相比较,宽带直接处理方法BASS-ALE和FDM具有更好的性能,其原因是宽带直接处理方法不需要构造聚焦矩阵,也不需要方位预估,避免了这些因素对子空间谱及方位估计的影响.     

数学娱乐(六)——移棋相间

移棋相间(移动白色棋子和黑色棋子变成黑色棋子和白色棋子相间)是一个悬而未决的问题,本文获得一般的移动棋子规律.     

三维Boussinesq方程在有界区域的爆破性准则

研究了三维Boussinesq方程在带有光滑边界条件下有界区域的爆破性问题,由于耗散项和边界的影响,证实了方程中速度项的梯度控制其解的爆破性,并且速度场比温度函数起着更重要的作用.