利用Pearson相关系数定量分析生物亲缘关系

论文主要利用计算语言学中使用的统计学方法定量分析生物物种的亲缘关系。以包含生物体遗传信息的核酸序列为研究对象,采用计算语言学的思想和方法,将每一个生物体的核酸序列看作一篇很长的自然语言文本,抽取核酸序列的双核苷酸频率分布特征向量,用以表征其数字特征。而后采用PearsonCorrelationCoefficient(Pearson相关系数)定量分析其亲缘关系的远近程度。将119个细菌的全基因组核酸序列进行两两比对,对所得的7021个r值进行分析,得出的结论是:亲缘关系越相近的物种,其Pearson相关系数越大。取定0.985作为“属”的分界阈值时,得到召回率为75.824%,准确率为73.404%。论文对定量分析生物学核酸序列的相似性和对生物亲缘关系远近的建模有重要的实际意义。     

基于Pearson相关系数的Cache计时模板攻击方法

针对Cache计时模板攻击所采集数据噪声较多的问题,提出一种利用访问地址Cache命中率建立计时模板的方法,并根据Pearson相关系数对输入值进行判断。通过Flush+Reload攻击方法对计算机的键盘输入进行攻击,获取每个地址的Cache命中率,将Cache命中率高的地址转换为模板矩阵,利用该模板矩阵计算Pearson相关系数并根据系数大小判断输入值。实验结果表明,与均方误差法相比,该方法能够提高对输入值的判断准确率。     

Analysis of Bias in the Apparent Correlation Coefficient Between Image Pairs Corrupted by Severe Noise

The correlation coefficient r is a measure of similarity used to compare regions of interest in image pairs. In fluorescence microscopy there is a basic tradeoff between the degree of image noise and the frequency with which images can be acquired and therefore the ability to follow dynamic events. The correlation coefficient r is commonly used in fluorescence microscopy for colocalization measurements, when the relative distributions of two fluorophores are of interest. Unfortunately, r is known to be biased understating the true correlation when noise is present. A better measure of correlation is needed. This article analyses the expected value of r and comes up with a procedure for evaluating the bias of r, expected value formulas. A Taylor series of so-called invariant factors is analyzed in detail. These formulas indicate ways to correct r and thereby obtain a corrected value free from the influence of noise that is on average accurate (unbiased). One possible correction is the attenuated corrected correlation coefficient R, introduced heuristically by Spearman (in Am. J. Psychol. 15:72–101, 1904). An ideal correction formula in terms of expected values is derived. For large samples R tends towards the ideal correction formula and the true noise-free correlation. Correlation measurements using simulation based on the types of noise found in fluorescence microscopy images illustrate both the power of the method and the variance of R. We conclude that the correction formula is valid and is particularly useful for making correct analyses from very noisy datasets.     

Using Pearson Correlation to Improve Envelopes around the Distributions of Functions

Given two random variables whose dependency relationship is unknown, if a new random variable is defined whose samples are some function of samples of the given random variables, the distribution of this function is not fully determined. However, envelopes can be computed that bound the space through which its cumulative distribution function must pass. If those envelopes could be made to bound a smaller space, the cumulative distribution, while still not fully determined, would at least be more constrained. We show how information about the correlation between values of given random variables can lead to better envelopes around the cumulative distribution of a function of their values.     

基于相关系数的相关跟踪算法研究

提出了一种以相关系数作为相似度度量准则的相关跟踪算法，克服了传统的以点对点乘累加作为相似度度量准则的相关跟踪算法跟踪精度低的缺点。给出了相似性度量的快速实现方法，解决了目标跟踪的实时性要求。同时．还提出了一种新的模板更新策略，使得跟踪算法对环境的适应能力和稳定性得到较大的提高。此外，提出了跟踪失败判决策略，解决了因目标暂时消失或环境突然变化，如瞬间明暗变化，造成的成像质量差而引起的跟踪失败。试验结果表明，该相关跟踪算法减少了相关跟踪的复杂度，具有跟踪精度高和速度快的特点。目前，该算法已经应用在实时目标跟踪系统中。     

基于噪声分析的椒盐噪声降噪处理方法

针对传统的中值滤波降噪方法不能有效去除图像中的椒盐噪声,提出基于噪声分析的椒盐噪声降噪处理方法。算法根据椒盐噪声仅仅改变图像部分像素值为0和255、其余像素并未改变的特点,首先判断图像的噪声点和信号点,针对噪声点,统计邻域中信号的个数,然后根据信号的个数决定采用某个邻域的中值去代替噪声点,从而达到去除椒盐噪声的目的。仿真实验表明,该算法能有效去除图像的椒盐噪声并较好地保留图像的边缘细节信息。     

高精度噪声系数测量系统整体校准方法研究

利用"源端失配误差修正的冷噪声测量技术"的高精度噪声系数测量系统问世以来,得到了噪声测试工程师的广泛认可,其主要特点是在系统自校准和测量两个环节中,都使用了一个阻抗调配器呈现不同(4~7个)源阻抗状态,从而降低甚至消除测量过程中的源端失配误差,提高了噪声系数测量精度。这种崭新的测量系统给计量工作带来了困扰,主要原因是测量系统组成更加复杂,测量技术考虑失配因素,测量模型技术保密等。论文提出一种全新的整体校准方案,建立了校准模型,通过实际案例分析证实基本解决了该校准难题。     

基于网络化的噪声系数测试系统设计

为了解决雷达整机级噪声系数自动测试的难题,采用非线性测试方法,用矢量信号源产生基准功率噪声,通过网络化的通信方式,实现测试的自动控制与采集.系统对引入的误差和不确定度进行讨论,并对不同状态下的基准噪声功率进行量化分析,总结推演出基于非线性系统的噪声系数测试理论算法,实现了雷达整机噪声系数的嵌入式自动测试.经过使用验证,系统测试符合设计要求,测试效率得到显著提高.     

针对声屏障的轨道交通的降噪研究

该文针对目前轨道交通中普遍使用的声屏障的降噪方案,提出了在轻轨轨道间增加双面吸声声屏障的新方案,以此来达到进一步降噪的目的。运用边界元方法,建立轨道声屏障降噪的边界元分析模型,利用边界元仿真软件SYSNOISE得到仿真结果,在此基础上预测声屏障的降噪效果。并研究分析了声屏障高度对降噪性能的影响,通过对比不同高度的降噪性能,得到最佳声屏障高度。最终通过对两种方案的降噪结果的对比,说明新的方案具有更好的降噪效果。     

Noise Reduction Algorithms in a Generalized Transform Domain

Noise reduction for speech applications is often formulated as a digital filtering problem, where the clean speech estimate is obtained by passing the noisy speech through a linear filter/transform. With such a formulation, the core issue of noise reduction becomes how to design an optimal filter (based on the statistics of the speech and noise signals) that can significantly suppress noise without introducing perceptually noticeable speech distortion. The optimal filters can be designed either in the time or in a transform domain. The advantage of working in a transform space is that, if the transform is selected properly, the speech and noise signals may be better separated in that space, thereby enabling better filter estimation and noise reduction performance. Although many different transforms exist, most efforts in the field of noise reduction have been focused only on the Fourier and Karhunen–LoÈve transforms. Even with these two, no formal study has been carried out to investigate which transform can outperform the other. In this paper, we reformulate the noise reduction problem into a more generalized transform domain. We will show some of the advantages of working in this generalized domain, such as 1) different transforms can be used to replace each other without any requirement to change the algorithm (optimal filter) formulation, and 2) it is easier to fairly compare different transforms for their noise reduction performance. We will also address how to design different optimal and suboptimal filters in such a generalized transform domain.      

高速列车受电弓气动噪声分析与降噪研究

随着列车速度的大幅提升,气动噪声问题愈发凸显。受电弓噪声在整车噪声中占较高位置,为研究高速列车受电弓气动噪声特性,通过Lighthill声学理论的宽频噪声模型对高速列车气动噪声源进行识别,利用定常SST k-w湍流方法分析高速列车受电弓的流场特性;基于大涡模拟与FW-H声学比拟理论计算高速列车受电弓远场气动噪声。数值算例结果表明,受电弓部位的碳滑板、弓头为受电弓主要噪声源;以轨道中心线为对称线,远场气动噪声监测点的声压级及频谱特性表现出较高的对称性;在同一列车运行速度下,监测点声压级随离轨道中心线距离增大而减小,列车以不同速度运行时,其声压级降低的幅值相差较小;高速列车远场气动噪声为宽频噪声,主要能量集中在500Hz~5000Hz。提出一种射流降噪方法,在350km/h速度下,监测点总声压级值降低了15.2dB。     

Audible Noise Reduction in Eigendomain for Speech Enhancement

A signal subspace scheme based on masking properties is proposed for enhancement of speech degraded by additive noise. Since the masking properties are related to the critical frequency band that is derived from the characteristics of human cochlea, the incorporation of masking threshold into a subspace technique requires the transformation between the frequency and eigen domains. We present and apply an invertible transformation between the frequency and eigen domains. In this paper, we use masking properties of the human auditory system to define the audible noise quantity in the eigendomain. We derive the eigen-decomposition of the estimated speech autocorrelation matrix with the assumption of white noise. Subsequently, an audible noise reduction scheme is developed based on a signal subspace technique, and the implementation of our proposed scheme is outlined. We further extend the scheme to the colored noise case. Simulation results show the superiority of our proposed scheme over other existing subspace methods in terms of segmental signal-to-noise ratio (SNR), perceptual evaluation of speech quality (PESQ), modified Bark spectral distortion (MBSD), spectrogram and informal listening tests.     

论广义相关性在柔性逻辑中的重要性

本文用测度论的观点,证明柔性逻辑中命题连接词的运算模型是连续可变性的算子族,它受广义相关系数h的控制,并给出了h的物理意义和计算公式,最后,用实例说明了柔性逻辑的方法比CRI和三Ⅰ方法更合理。     

目标跟踪中巴氏系数误差的分析及其消除方法

在meanshift的目标跟踪方法中,Taylor公式的近似展开会造成优化过程中Bhattacharyya系数值的误差,这种误差会给目标跟踪带来偏差,同时不适合快速运动目标的跟踪.针对Bhattacharyya系数的Taylor公式近似表示情形,研究了这种近似表示引起的系数误差和对目标跟踪的影响,在此基础上,将Bhattacharyya系数的优化问题转化为求解约束优化问题,从而提出一种改进的目标跟踪方法,以达到提高目标跟踪的精度,而且证明了该改进方法的收敛性.实验表明文中方法对于快速运动目标的跟踪具有更好的跟踪精度.     

小波变换阈值降噪方法及在工程中的应用

研究了基于小波变换的信号降噪的原理和方法,从中选择阈值法降噪.详细论述了该方法的原理,特点和利用MatLAB中小波分析工具箱进行设计的步骤.对rigrsure,heursure,sqtwolog和minimax 4种阈值选择方法进行了定性和定量比较,并实现了压力信号降噪的计算机仿真.通过比较,得出在处理实际输油管道泄漏的压力信号时,sqtwolog阈值选择方法能够更有效去除噪声.     

PXI总线雷达噪声系数测试卡设计与实现

PXI总线雷达噪声系数测试卡是将基于PXI总线的虚拟仪器技术应用于雷达噪声系数测试的首次尝试,对于改进雷达装备性能测试方式及仪器具有较大意义;通过对雷达噪声系数原理以及测试方法的分析讨论,确定了测试方案,并完成了功能电路的设计;采用了专用接口芯片结合CPLD的方法实现了PXI总线接口协议以及噪声系数测试卡的逻辑控制电路,利用DriverStudio软件编写了硬件驱动,并完成了基于LabWindows/CVI的虚拟面板的设计;测试卡在实测中能够稳定地工作,测量精度满足设计指标.     

一种基于属性重要性的变精度粗糙集属性约简算法

结合胡可云算法中对属性重要性的描述,以条件属性在可辩识矩阵中出现的频率作为启发信息,提出一种基于变精度粗糙集模型的属性约简算法.实验证明,该方法能够有效地对决策表进行属性约简,并具有一定的抗噪声能力.     

雷达接收机噪声系数测试仪的研究与设计

用自行研制的PC虚拟仪器卡以军用工控机为平台构成一个智能化的通用雷达接收机噪声系数测试仪 ,完成对多种雷达接收机噪声系数的测试 ,并给出了实现自动测试的软件表达