一种流数据立方体分析挖掘框架

流数据是目前一种重要的数据展现形式,对流数据进行OLAM(联机分析挖掘)操作可为分析人员提供多层次的数据视图。但OLAM要求在不同粒度中实现对数据的聚合操作,而流式数据内含时态特性和持续到达特性,使得数据无法被多次重复操作。使用传统OLAP(联机分析处理)方法无法生成部分物化视图且流数据规模宏大,受限于存储空间大小而无法保存全部数据单元信息。针对上述问题,提出了一种基于概要技术的流数据OLAM框架——sketch cube(概要立方体),该框架把任意维度组合映射成唯一自然数,根据上下限单调原则对维度组合裁剪,在类线性空间中保存有效数据单元信息,并构建时间序列索引提高检索效率。通过理论分析给出使用sketch cube的前提条件,同时通过真实海量流数据实验分析表明,sketch sube在有效性、存储空间效率和正确率上可以满足实时挖掘的需求。     

一种基于稀疏矩阵灵敏度计算的方法

本文建立了无需对电路进行任何预处理的稀疏矩阵电路方程.在此基础上推导出一种只需进行一次电路分析即可求得所有支路电流电压对电路参数的各阶灵敏度的递推方法,使计算机自动建立电路方程和高阶灵敏度求解的实现变得较为容易.对于采用其他方法建立的电路方程,只要其满足MX=b的形式且为线性的,就可以利用本文递推公式求灵敏度.该方法方便有效,易于编程,有一定的实用价值.     

SAR图像特征数据立方体的构造

图像数据立方体的建立有助于图像数据的基于视觉内容的分析和多种知识的挖掘,包括汇总、分类、比较、关联和聚类.图像数据立方体对于图像分析是很有用的模型.实现一个维数很大的数据立方体是很困难的.但如果维数不够,则会使图像的建模范围过于粗糙、受到限制和不精确的扩展.因此,如何设计出既能满足效率要求,又能有足够的表达能力的图像数据立方体,是个亟待研究的问题.文中借鉴前人的思路和方法,构造了SAR图像立方体的模型.     

在数据仓库中如何有效地实现数据立方体的计算

有效的实现数据立方体的计算是提高数据仓库查询效率的有力方法。在设计方体时要对方体维护成本和查询响应时间这两个因素加以考虑，从而产生了方体的部分物化和全物化两种方法。通过对数据仓库中如何有效的进行数据立方体计算的讨论，提出了实现数据立方体部分物化和全物化的算法。     

商覆盖立方体的一种增量维护策略

通过建立一种新的商覆盖立方体增量维护策略,将商覆盖立方体分成多个子集,在判断是否需要进行新增或修改操作时,不再需遍历整个商覆盖立方体而只需遍历部分子集,从而缩短了进行增量维护所需的时间。在实现这种策略中提出了基本表中新增记录时的算法Up-dateAddNew。实验结果表明,采用该算法时,需要访问的记录数仅为传统方法的85%。     

一种新的数据预处理方法

根据雷达理论可知,提高虚警概率可以提高检测概率,对于弱小目标及远距离目标的检测十分有效,然而受到数据处理能力的限制,通过提高虚警概率实现提前发现目标的方法没有得到充分利用。本文提出的数据预处理新方法可以有效的剔除杂波点,对提高雷达的作用距离及弱小目标的检测十分有利。     

一种组稀疏高阶变分的图像复原模型

为了更好地利用图像的稀疏性以提高变分模型的图像复原性能,在自适应高阶变分模型中对图像的一阶梯度加以组稀疏限制,建立一种非凸的组稀疏高阶变分模型.为实现该非凸模型的优化求解,采用交替方向乘子法将模型的极小化问题分解成多变量的子问题,进而采用IRL1与MM算法分别求解高阶变分与组稀疏极小化问题,实现退化图像的复原处理.通过...     

一种两维稀疏的3D-SAR成像方法

下视阵列3D-SAR避免了多次飞行带来的去相关问题并且能够很好解决侧视SAR成像存在的阴影、叠掩等问题。但是常规下视阵列3D-SAR跨航向阵元数目较多,增加了系统的成本和复杂度;而且雷达数据需要在三个维度进行采样,回波数据量大。针对以上问题,本文提出了一种跨航向和航迹向两维稀疏的3D-SAR成像算法。在跨航向进行阵列天线随机布局,减少了阵列天线的阵元数目,在航迹向随机稀疏采样,减少了航迹向采样点数。本文采用正交匹配追踪方法对两个维度数据进行稀疏重构。最后,通过点目标仿真实验验证了成像算法的有效性。      

一种新的数据隐藏方法

本文提出一种新的数据隐藏方法,对于给定长为n比特的可修改宿主数据流,至多修改1比特宿主数据,可嵌入log₂(n+1)比特的数据.嵌入/提取矩阵 H ,还可作为密钥,使得嵌入数据具有较好的安全性.该方法已在微机上进行了模拟,获得了预期的结果.     

一种新的基于稀疏表示的宽带信号DOA估计方法

该文提出一种基于稀疏表示的宽带信号波达方向(DOA)估计方法,解决稀疏表示方法在宽带信号DOA估计中由于基矩阵维数过大而使算法存储量和重构计算量大的问题。用单一频点的基矩阵代替频率和角度联合构建的基矩阵,使基矩阵的列数仅相当于一个频点处冗余基矩阵的列数,大大降低了稀疏重构方法的存储量和计算量。该方法首先对各频点的频域数据进行聚焦处理,将不同频率的数据堆叠到参考频率上并建立参考频率处的基矩阵,然后建立聚焦后的稀疏表示模型进行DOA估计,并采用奇异值分解进一步降低算法的运算量,最后给出残差门限的选择方法。该算法不仅适用于非相关信号,也可直接处理相关信号而不需要任何的去相关运算,且具有高的检测概率和估计精度,仿真实验和分析验证了该方法的有效性。     

A new method to compute registration error from DFM type teststructures

A new method to compute registration error from the slanted die-fit-monitor (DFM)-type test structures using an on-line calibration curve has been presented. The method is suitable for use in Keithley 350, parametric measurement systems for estimation of registration error during measurement where available computing power is limited. The results obtained from this method are compared with the registration errors calculated from the standard DFM structure     

A new method to compute reliability of repairable m-out-of-n systems by arbitrary distributions

In this paper it is presented a new method to compute reliability characteristics of repairable m-out-of-n systems by arbitrary distributed time to failure and time to repair. The method allows to consider the systems with large number of units and does not take much computational times.     

A new algorithm to compute the DCT and its inverse

A novel algorithm to convert the discrete cosine transform (DCT) to skew-circular convolutions is presented. The motivation for developing such an algorithm is the fact that VLSI implementation of distributed arithmetic is very efficient for computing convolutions. It is also shown that the inverse DCT (IDCT) can be computed using the same building blocks which are used for computing the DCT. A DCT/IDCT processor can be designed to compute either the DCT or the IDCT depending on a 1-b control signal     

A new algorithm to compute the discrete inverse radon transform

The aim of this paper is to compute the discrete inverse Radon transform over ⁿ . The Radon transform is a function with domainS ^n–1×. It is shown that under different measure this function can be defined with domain ⁿ . In this case one can compute the discrete inverse Radon transform in the Cartesian coordinate system without interpolating from polar to Cartesian coordinates or using the backprojection operator.     

一种基于稀疏矩阵的指纹识别新方法

为了实现对指纹识别速度上的需求,对指纹算法做了较深入的探讨和分析,提出一种新的指纹匹配算法,该算法将稀疏矩阵应用到指纹匹配当中,根据稀疏矩阵计算速度快和存储容量小的特点,使得指纹匹配速度在一定程度上得到了提升。通过实验结果表明,本文算法在指纹图像增强和匹配速度方面有很大的提高,同时也降低了计算机的内存消耗。     

A direct method to compute the coupling between nonidentical microwave cavities

A new technique to compute the coupling, as a function of frequency, between nonidentical resonators is presented in this paper. The structure is separated by introducing electric and magnetic wall boundary conditions on the plane of separation, and coupling coefficient is computed directly from the eigenvalues of the four individual structures. The proposed technique has been used to compute the coupling between coaxial combline resonators. It is found to be computationally much faster than the iterative technique. The computed results are in good agreement with the measured results.     

基于稀疏表示的船体检测方法研究

为进一步强化航道安全，解决海事CCTV人工值守、非自动化问题，提出了基于稀疏表示的船体检测方法。利用稀疏表示实现对船体的检测时，首先构建样本特征矩阵，然后利用K-SVD算法对样本特征矩阵进行学习，得到冗余字典，最后对测试样本进行重构，根据马氏距离判断测试样本属性。通过与传统方法的试验比较，实验结果表明，该算法实时性好、检测准确率高，可以很好地对CCTV视频监控的船体进行检测与跟踪，解决CCTV人工值守、非自动化问题，节省大量人力资源。     

A fast method to compute the potential in the multisphere model[EEG application]

A series expansion is derived for the potential distribution, caused by a dipole source in a multilayered sphere with piecewise constant conductivity. When the radial coordinate of the source approaches the radial coordinate of the field point the spherical harmonics expansion converges only very slowly. It is shown how the convergence can be improved by first calculating an asymptotic approximation of the potential and using the so-called addition-subtraction method. Since the asymptotic solution is an approximation of the true solution, it gives some insight on the dependence of the potential on the conductivities. The formulas are given in Cartesian coordinates, so that difficulties with coordinate transformations are avoided. Attention is paid to the (fast) computation of the partial derivatives of the potential, which is useful for inverse algorithms     

Extension of the Pisarenko method to sparse linear arrays

When applied to array processing, the Pisarenko harmonic decomposition (PHD) method is limited to linear equispaced arrays. We present an approach that allows us to extend it to general arrays, although for the ease of exposition, we consider only sparse linear arrays. We exploit the fact that the PHD can be seen as a deconvolution or model-fitting approach that minimizes an t₁ norm and can thus be implemented as a standard linear program. Looking at the PHD from this point of view has two advantages: it allows us to extend its applicability to arbitrary arrays, and by diverging slightly from the basic philosophy, it allows us to improve its performance, which is often quite poor in its original version