Analogy and duality of texture analysis by harmonics or indicators

According to the classic harmonic approach, an orientation density function (odf)f is expanded into its corresponding Fourier orthogonal series with respect to generalized spherical harmonics, and a pole density function (pdf) into its corresponding Fourier orthogonal series with respect to spherical harmonics. While pdfs are even (antipodally symmetric) functions, odfs are generally not. Therefore, the part of the odf which cannot be determined from normal diffraction pdfs can be mathematically represented as the odd portion of its series expansion. If the odff is given, the even part can be mathematically represented explicitly in terms off itself. Thus, it is possible to render maps ofharmonic orientation ghosts, and to evaluatevariants of mathematical standard odfs resulting in identical pdfs independent of pdf data. However, if only normal diffraction pdfs are known, the data-dependentvariation width of feasible odfs remained unaccessible, and within the harmonic approach a measure of confidence in a solution of the pdf-to-odf inversion problem does not exist.According to any discrete approach, an odff defined on some setG of orientations is expanded into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofG, and a pdf defined on the upper (lower) unit hemisphereS ₊ ^{3 3} into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofS ₊ ³ . The ambiguity of the pdf-to-odf inversion problem is discussed in terms of column-rank deficiency of the augmented projection matrix. The implication of the harmonic approach to split an odf into auniquely determined and anundetermined part does no longer seem to be reasonable. However, it is possible to numerically determine data-dependent confidence intervals for the Fourier coefficients with respect to the indicator functions which can be immediately interpreted as mean orientation densities within the elements of the partition ofG. Doing so for all Fourier coefficients in the finite series expansion, i.e. for all elements of the partition of the setG, eventually results in the data-dependent variation width of odfs feasible with respect to given pdf data, and to the partitions ofG andS ₊ ³ .Thus it is confirmed that the appearance of orientation ghosts, in particular correlations oftrue andghost orientation components, depends on the representation of an odf. It may be questioned whether in practical applications the implicit assumption of the harmonic method that the even part can be determined uniquely and free of error is generally a reasonable initial condition to develop ghost correction procedures.     

广义逆的计算与最小二乘估计

给出了某些广义逆的计算方法,将这些结果应用于观测系统的参数估计,给出了系统无加权和加权最小二乘的最新估计结果,推广了[1]的工作,同时简化了[2]中求多个相容矩阵方程公共解的算法。     

基于GPCA的中部省际农村居民生活水平动态分析

文章首先构建评价农村居民生活水平的指标体系,之后运用全局主成分分析法（GPCA）,实证研究了我国中部各省农村居民从2001年－2006年生活水平的时间演变,并对结果进行了比较分析。     

地磁场极值预测及磁暴感应地电场有限元计算

基于兰州地磁台的地磁观测数据,利用基于广义帕累托分布(GPD)的超阈值模型对磁暴期间地磁场的水平分量值和分钟变化率进行拟合,并利用轮廓似然函数对地磁场重现水平进行了预测.通过对中纬度地区的5个地磁台重现值结果的综合分析,给出100年一遇和200年一遇的磁暴期间地磁场分钟变化率.利用大地电磁测深数据构建了华北地区三维电导...     

柔性臂动力学建模及比较研究

根据广义坐标的不同定义应用Lagrange方程建立了两种表达形式的水平面内转动的两自由度柔性机械臂动力学模型；分析了两类方程的不同特点和适用领域；将模型的仿真结果和实验结果进行对比分析，验证了模型的准确性；为柔性臂动力学分析和下一步研究提供了理论指导及重要的前提条件。     

视频字符叠加器

文章介绍了实现在电视信号上叠加字符的方法，并具体给出了一个实际用于水井电视检修的视频字符叠加器的软硬件。     

封闭型(6,0)单壁碳纳米管电子传输特性研究

采用广义梯度近似(Generalized gradient approximation,GGA)密度泛函理论与非平衡态格林函数(Non-equilibrium Green’s function,NEGF)相结合的方法对两端封闭型单壁(6,0)碳纳米管进行电子传输的理论研究。在温度为300K的条件下,对不同长度(6,0)单壁碳纳米管(SWNT)进行电子透射概率计算。结果显示,两端封闭型(6,0)碳纳米管的电子传输属于量子化传输模式,并随着碳纳米管长度的增加,某些电子透射概率峰值所对应的能量值并未有大的变化,且呈现线性分布;两端封闭型单壁(6,0)碳纳米管中电子的传输接近无散射弹道传输模式,该系统概率尖峰能量的平均间距约为n×2.2eV,n为整数且1≤n≤6。     

统一混沌系统同步及其保密通信

文中研究了混沌系统的广义同步和基于状态观测器同步。利用这两种同步方法,研究了统一混沌系统同步。研究发现:同步后的响应系统能保持混沌状态。在基于状态观测器同步的基础上,提出了全双工保密混沌通信系统,理论分析和仿真实验证明了该通信方案的可行性。     

Deterministic Time-Varying Packet Fair Queueing for Integrated Services Networks

In integrated services networks, the provision of Quality of Service (QoS) guarantees depends critically upon the scheduling algorithm employed at the network layer. In this work we review fundamental results on scheduling, and we focus on Packet Fair Queueing (PFQ) algorithms, which have been proposed for QoS wireline-wireless networking. The basic notion in PFQ is that the bandwidth allocated to a session is proportional to a positive weight _i . Because of the fixed weight assignment, the inherent in PFQ delay-bandwidth coupling imposes limitations on the range of QoS that can be supported. We develop PFQ with deterministic time-varying weight assignments, and we propose a low-overhead algorithm capable of supporting arbitrary piecewise linear service curves which achieve delay-bandwidth decoupling. Unlike existing service-curve based algorithms, our time-varying PFQ scheme does not exhibit the punishment phenomenon, and allows sessions to exploit the extra bandwidth in under-loaded networks.