基于LZ复杂性距离的蛋白质三维结构比较

基于LZ复杂性距离提出了一种非比对的蛋白质三维结构比较方法.该方法以蛋白质结构单元间的条件LZ复杂性为特征参数,根据条件LZ复杂性计算LZ复杂性距离来作为蛋白质三维结构(不)相似程度的定量刻画.该方法可在二次多项式的时间限度内计算完成.蛋白质的结构数据采用接触图的表示方式,以避免PDB格式数据中的非结构信息和不同坐标系对结构比较的影响.以真实的蛋白质三维结构数据所组成的5个数据集为实例,基于LZ复杂性距离对各数据集中的蛋白质单链进行了结构聚类.聚类的结果符合各蛋白质单链在传统的结构分类数据库中的分类,表明论文提出的方法能够有效地对蛋白质三维结构进行定量比较.     

g-r循环矩阵求逆的快速算法

利用FFT,给出g-r循环矩阵求逆的快速算法,计算复杂性为O(n log2 n) (g 2)n。     

赤潮生物原甲藻Prorocentrum分子识别和系统发育学研究

对东海原甲藻Prorocentrum donghaiense、海洋原甲藻P.micans、微小原甲藻P.minimum、立玛原甲藻P.lima(CCMP1966)四种赤潮生物的18S rDNA进行了PCR扩增和全序列测定及分析,比较了它们的遗传距离和相似系数,获得其18S rDNA序列中的三处高变异区,为设计快速识别原甲藻种间分子探针提供分子依据.同时结合12种具有代表性的重要赤潮甲藻的18S rDNA序列,采用邻接法(Neighbour-Joining,NJ)和最大似然法(Maximum Likelihood,ML)构建系统发育树,研究原甲藻的种间关系和进化地位,结果表明,营底栖生活的P.lima与营浮游生活的P.micans、P.minimum、P.donghaiense为多系起源,浮游型原甲藻与凯伦藻Karenia有更近的起源关系.     

人体微小管状血管血液流速自动测量方法研究

提出了一种基于视频图像序列的人体微小管状血管血液流速自动测量方法.在提取血管中心线时采用基于图像帧序列方差的种子点自动选取方法,设计了基于Hessian矩阵的血管中心线提取的迭代算法;提取血管中心线后,根据连续帧图像的中心线灰度统计曲线,计算出血液流速.结果表明:该方法测量速度快、精度高,与专家测量结果之间的相关系数为0.901 4.     

行星齿轮箱齿轮磨损故障诊断

为解决行星齿轮箱故障诊断方法专业性要求高、计算过程复杂以及模型训练时间长等问题,提出一种基于PCA-EDT-DBN的行星齿轮箱故障诊断新方法。利用PCA分析多个传感器采集到的振动信号并根据需求取每列信号的前p个主成分,将每列信号的前p个主成分合成一维序列。计算每两列数据前p个主成分之间的欧氏距离得到距离矩阵,将该矩阵按序展开成一维序列。将得到的两个一维序列合成一个一维序列作为样本输入到DBN中对模型进行训练,再有新样本输入到训练好的模型中则可智能地给出分类结果,从而实现对设备的故障诊断。此外,为提高模型诊断准确率,提出利用正交试验对DBN参数进行优化。利用行星齿轮箱齿轮磨损预置故障实验数据验证了该方法的有效性,结果表明该方法诊断准确率高、训练时间短且计算过程简单。     

一个MTCM-OFDM系统模型及其性能的分析

提出了一种将多网格编码调制(MTCM)与正交频分复用(OFDM)系统相结合的方法,建立了一个MTCM-OFDM系统模型,并对其进行了性能分析和仿真.分析表明,MTCM可提高系统的误码率性能,将MTCM应用于OFDM系统,能增大OFDM符号内一组子载波上符号序列之间的欧氏距离,从而降低误码率,但不会造成信息速率和带宽效率的损失.根据MTCM网格图中不同状态下输出符号序列可以有较大欧氏距离的特点,给出了一种符号序列的两步检测算法:首先利用最大似然序列检测以较大概率检测出网格图的状态序列,然后在两个连续的状态之间检测判决符号序列.该算法利用了MTCM编码调制的特点,因而时延小、复杂度低,性能逼近直接的一步最大似然检测.理论分析和仿真结果均证明了MTCM-OFDM系统和这种检测算法的上述性能特点.     

多尺度模糊熵及其在滚动轴承故障诊断中的应用

提出了一种新的时间序列复杂性度量的方法——多尺度模糊熵(multiscale fuzzy entropy,简称MFE)。多尺度模糊熵是基于模糊熵而定义的。模糊熵作为样本熵的改进,是对时间序列复杂性和无规则程度的度量,而多尺度模糊熵则在模糊熵的基础上引入了尺度因子,是对时间序列在不同尺度因子下复杂性的量度。与样本熵、模糊熵和分形维数等其他表征复杂性的非线性动力学方法相比,多尺度模糊熵包含更多时间模式信息。论文首先介绍了模糊熵和多尺度模糊熵的概念,并将其应用于滚动轴承振动信号复杂性的量度,由此提出了一种基于多尺度模糊熵和支持向量机的滚动轴承故障诊断方法。试验数据分析表明,新提出的方法能有效地提取故障特征,实现故障类型的诊断。     

一种无监督学习的异常行为检测方法

针对智能视频监控的需求,提出一种无监督学习的异常行为检测方法。首先,采用混合高斯模型建模提取出运动目标,对运动区域进行标记;然后提取运动区域内的光流信息,将其归一化成特征矩阵,并建立实时更新的特征矩阵观测序列;最后利用二维主成分分析(2DPCA)的重构原理对观测序列进行分析,根据重构特征矩阵与原特征矩阵的能量比来判断是否存在异常行为。基于不同数据库下的视频序列实验结果验证了所提方法的有效性。     

坛紫菜5.8S rDNA和ITS区片段的序列分析及应用

对坛紫菜(Porphyra haitanensis)野生(GL)和栽培(PXV)品系的5.8S rDNA-ITS兀区进行了PCR扩增和序列分析,扩增的GL和PXV的DNA片段长度分别为1213 bp和1221bp,包含完整的ITS1-5.8S-ITS2区.然后对紫菜7个种9个品系(其中6种7个品系从GenBank数据库中获得)的rDNA相应序列进行了排序和系统进化分析,结果表明:9个紫菜品系rDNA中5.8S区的长度和序列非常保守,而ITS区的长度和序列则变异较大;根据它们的序列差异,计算出这9个紫菜品系的遗传距离在0.010～0.551之间,遗传相似性在44.9%～99%之间;并且采用邻接法构建了这9个紫菜品系的系统发育树,发现可以明显分为4个进化枝,由此讨论了分子分类方法同传统分类方法的分歧.实验结果表明,5.8S rDNA.ITS区序列可以成为紫菜种质鉴定和系统进化研究的强有力工具.     

海带栽培品系和长海带ITS区的PCR扩增及序列分析

对遗传背景清晰且具有显著表型差异的海带6个栽培品系(CUL002,CUL860,CUL1170,CUE017,CUE018,CUL901)和长海带(L．longissia)的ITS区进行了PCR扩增和序列测定,并分析了8个种17个品系(其中7种共10株从GenBank中获得)海带之间的系统进化关系。结果表明：表型各异的6个海带栽培品系ITS区差别很小,其中ITS1 5．8S rDNA序列完全相同,部分品系间ITS2序列有个别碱基差异;进化树显示与日本海带(L．japonica,AF319018)聚在一起,相似性大于98％,其中CUL901、CUL860和CULll70的ITS序列完全相同。长海带(L．longissia)的ITS 5．8S rDNA和日本海带(L．japonica,AF319018)的完全相同。以Undaria peterseniana为外类群,根据ITS 5．8S rDNA序列构建进化树,6栽培品系及长海带与日本海带聚在一起;17株海带基本构成两个大的进化枝。研究结果揭示了我国海域栽培的长海带可能与日本海带(L．iaponica,AF319018)为同一个种。     

Influence of step complexity and presentation style on step performance of computerized emergency operating procedures

With the development of information technology, computerized emergency operating procedures (EOPs) are taking the place of paper-based ones. However, ergonomics issues of computerized EOPs have not been studied adequately since the industrial practice is quite limited yet. This study examined the influence of step complexity and presentation style of EOPs on step performance. A simulated computerized EOP system was developed in two presentation styles: Style A: one- and two-dimensional flowcharts combination; Style B: two-dimensional flowchart and success logic tree combination. Step complexity was quantified by a complexity measure model based on an entropy concept. Forty subjects participated in the experiment of EOP execution using the simulated system. The results of data analysis on the experiment data indicate that step complexity and presentation style could significantly influence step performance (both step error rate and operation time). Regression models were also developed. The regression analysis results imply that operation time of a step could be well predicted by step complexity while step error rate could only partly predicted by it. The result of a questionnaire investigation implies that step error rate was influenced not only by the operation task itself but also by other human factors. These findings may be useful for the design and assessment of computerized EOPs.     

周期二元序列的线性复杂度及其稳定性分析

密码学意义上强的序列不仅应该具有高的线性复杂度而且其线性复杂度必须稳定,k-错线性复杂度用来反应线性复杂度的稳定性。本文基于x~(p~(m_2~n))-1在GF(2)上具有明确的分解式,研究了p~(m_2~n)-周期二元序列的线性复杂度和k-错线性复杂度之间的关系,然后说明了同时使得线性复杂度和k-错线性复杂度都达到最大值的p~(m_2~n)-周期二元序列是存在的。这里p是一个奇素数,2是模p~2的本原根。     

滚动轴承复合故障振动建模及Lempel-Ziv复杂度评价

故障建模是探寻机械诊断中认知规律的关键环节。为了更能准确地预知振动特征,研究滚动轴承结合面间的多体接触与传递过程的耦合作用,根据Hertzian理论建立一种详细的计及内圈-外圈-轴承座传递过程的6DOF振动模型。从轴承实际运动学的角度刻画故障的形成及渐进发展过程,进而实现单点、复合故障的有效模拟,并与实验结果进行了比较。轴承运行过程中故障状态的变化,必然导致振动信号复杂性的变化。基于非线性动力系统理论,引入Lem-pel-Ziv复杂度指标评价运行状态。结果表明,单点及复合故障的信号具有不同的复杂度,反映了不同故障状态的动力学响应的差异。Lempel-Ziv复杂度能有效描述轴承振动信号的复杂性,可作为量化指标用于滚动轴承状态评价。     

Rank formulas for certain products of matrices

For two matrix operations, calledquasi-direct sum andquasi-outer product, we determine their deviations from multiplicative behaviour of the rank. The second operation arises in the determination of the function table for so-called sum-type functions such as the Hamming distance. A consequence of the corresponding rank formula is, that the frequently used log rank can be a very poor bound for two-way communication complexity. Instead, as was shown in [9], a certainexponential rank gives often excellent or even optimal bounds.     

An ergonomics study of computerized emergency operating procedures: Presentation style, task complexity, and training level

Emergency operating procedures (EOPs) are widely used in nuclear power plants (NPPs). With the development of information technology, computerized EOPs are taking the place of paper-based ones. Unlike paper-based EOPs, the industrial practice of computerized EOPs is still quite limited. Ergonomics issues of computerized EOPs have not been studied adequately. This study focuses on the effects of EOP presentation style, task complexity, and training level on the performance of the operators in the execution of computerized EOPs. One simulated computerized EOP system was developed to present two EOPs, each with different task complexity levels, by two presentation styles (Style A: one- and two-dimensional flowcharts combination; Style B: two-dimensional flowchart and success logic tree combination). Forty subjects participated in the experiment of EOP execution using the simulated system. Statistical analysis of the experimental results indicates that: (1) complexity, presentation style, and training level all can significantly influence the error rate. High-complexity tasks and lack of sufficient training may lead to a higher error rate. Style B caused a significantly higher error rate than style A did in the skilled phase. So the designers of computerized procedures should take the presentation styles of EOPs into account. (2) Task complexity and training level can significantly influence operation time. No significant difference was found in operation time between the two presentation styles. (3) Training level can also significantly influence the subjective workload of EOPs operations. This implies that adequate training is very important for the performance of computerized EOPs even if emergency responses with computerized EOPs are much more simple and easy than that with paper-based EOPs.     

Weighted Gauss-Seidel Precoder for Downlink Massive MIMO Systems

In this paper, a novel precoding scheme based on the Gauss-Seidel (GS) method is proposed for downlink massive multiple-input multiple-output (MIMO) systems. The GS method iteratively approximates the matrix inversion and reduces the overall complexity of the precoding process. In addition, the GS method shows a fast convergence rate to the Zero-forcing (ZF) method that requires an exact invertible matrix. However, to satisfy demanded error performance and converge to the error performance of the ZF method in the practical condition such as spatially correlated channels, more iterations are necessary for the GS method and increase the overall complexity. For efficient approximation with fewer iterations, this paper proposes a weighted GS (WGS) method to improve the approximation accuracy of the GS method. The optimal weights that accelerate the convergence rate by improved accuracy are computed by the least square (LS) method. After the computation of weights, the different weights are applied for each iteration of the GS method. In addition, an efficient method of weight computation is proposed to reduce the complexity of the LS method. The simulation results show that bit error rate (BER) performance for the proposed scheme with fewer iterations is better than the GS method in spatially correlated channels.     

文本压缩技术综述

概述了数据压缩的起源及分类，并且对其中的一个重要组成部分-文本压缩的各种压缩算法：Huffman编码，算术编码，LZ系统算法等进行分析和讨论，比较它们的优缺点。     

An o(n) complexity recursive algorithm for multi‐flexible‐body dynamics based on absolute nodal coordinate formulation

A new algorithm called recursive absolute nodal coordinate formulation algorithm (REC‐ANCF) is presented for dynamic analysis of multi‐flexible‐body system including nonlinear large deformation. This method utilizes the absolute nodal coordinate formulation (ANCF) to describe flexible bodies, and establishes a kinematic and dynamic recursive relationship for the whole system based on the articulated‐body algorithm (ABA). In the ordinary differential equations (ODEs) obtained by the REC‐ANCF, a simple form of the system generalized Jacobian matrix and generalized mass matrix is obtained. Thus, a recursive forward dynamic solution is proposed to solve the ODEs one element by one element through an appropriate matrix manipulation. Utilizing the parent array to describe the topological structure, the REC‐ANCF is suitable for generalized tree multibody systems. Besides, the cutting joint method is used in simple closed‐loop systems to make sure the O(n) algorithm complexity of the REC‐ANCF. Compared with common ANCF algorithms, the REC‐ANCF has several advantages: the optimal algorithm complexity (O(n)) under limited processors, simple derivational process, no location or speed constraint violation problem, higher algorithm accuracy. The validity and efficiency of this method are verified by several numerical tests. Copyright © 2016 John Wiley & Sons, Ltd.     

MIMO-OFDM系统中一种新的信道估计方法

提出了多输入多输出-正交频分复用(MIMO-OFDM)系统中一种新的信道估计方法.根据最小均方误差的准则,推导出了求解信道频率响应的方程,方程求解的运算量主要集中在一个矩阵的求逆上.对每一个符号,此矩阵是固定的,所以矩阵的求逆仅需计算一次,整个求解过程的运算量较低.计算机仿真给出了这种方法的归一化均方误差和误码率性能.仿真结果表明,本文方法在多普勒频移为60Hz和360Hz下,其归一化的均方误差值相当,表明本文方法可以在不同的移动环境中良好工作.在不同的数据调制方式和不同的多普勒频移下,本文方法的误码率性能优于最小平方算法,略差于线性最小均方误差算法,但复杂度大大降低.