A method for sub-pixel scale feature-tracking using Radarsat images applied to the Mertz Glacier Tongue, East Antarctica

Tracking features between pairs of satellite synthetic aperture radar (SAR) images using image cross-correlation methods is a powerful tool for defining regions of image movement such as ice flow of Antarctic glaciers. Unlike optical images, processed SAR images have various instrumental effects such as view angle distortions and lateral displacement errors caused by slant range mapping. Co-registration issues are problematic and need to be addressed if there are few/no suitable stationary tie points at or near sea level within the images. Methods are presented that use Radarsat ScanSAR images to reliably measure sub-pixel displacements with errors of ? ± 0.25 pixels but this estimate is target dependent. The techniques and issues are illustrated using examples from a long-term study of the Mertz Glacier Tongue in East Antarctica. For image pairs only a few days apart, this extensive structure forms an excellent grid-like test pattern which provides up to 5000 valid correlation matches. Images separated by 100's of days can then be processed in the same way to reveal many subtle and some large changes over time. The technique described is robust and may be widely applicable.     

应用于动态异构web服务器的相似度求解方法

针对经典的基于编辑距离的字符串相似度计算方法计算效率低且准确率差的不足,提出一种基于编辑距离和最长公共子串的改进字符串相似度求解方法,引入最长公共前缀和最长公共后缀,定义新的相似度计算公式。将该方法应用于基于异构平台的动态异构web服务系统模型,通过网页篡改检测实验验证,与经典算法和经典公式相比,改进的相似度计算方法能够在适应自身差异性的基础上,提高相似度计算的准确性和计算效率。     

Development and evaluation of a pseudo-force approximation applied to nonlinear dynamic contacts and viscoelastic damping

A pseudo-force approximation method is used to study the nonlinear dynamic contacts and the effect of viscoelastic damping of beam-mass-beam systems. A pseudo-contact element with nonlinear stiffness and damping approximated by polynomial functions is defined and evaluated. To improve the system dynamic responses, viscoelastic damping is introduced into the systems using the standard linear model. The nonlinear forces derived from surface elasticity, penetration, instant contact velocity and viscoelastic damper are added to an excitation force vector to avoid reformation of system matrices. The system's equations of motion are directly integrated using the Wilson-θ method with minor modifications to accommodate the dynamic contacts and the viscoelastic damping. A design equation is also proposed to estimate the required viscoelastic dampers.     

Boundary element method applied to the analysis of thin plates

The classic Kirchhoff plate theory is formulated through integral representation decomposing the biharmonic field equation in two coupled harmonic equations. Two domain integrals appear, one inherent to the problem and the other due to the previous decomposition. Both of them are evaluated defining equivalent boundary integrations, using collocation method in several points on the boundary and the domain. These equivalent integrations are the same as those involved in the integral representation of the Poisson equation, therefore no extra integrations are needed.     

分析Lorenz系统动力学特征的新方法

为表征Lorenz系统复杂的动力学特征,提出了一种多分辨率复杂度算法。运用小波变换将信号分解成不同尺度下的各分量,采用滑动窗口依次计算了窗口内各分量的能量值、各能量值的信息熵,获取了动态的小波熵值--小波熵序列。仿真结果表明,多分辨率复杂度算法能够很好地表征Lorenz系统的过渡特征和演变特征,为Lorenz系统在混沌控制、同步等领域的应用提供了一种途径。     

涡轮流量计信号检出器的研制

信号检出器由永久磁钢、线圈、放大器、壳体等组成。永久磁钢的材质为铝镍钴,线圈骨架的材质为聚醚砜树脂,壳体采用XR-240灌封胶封装。基于运算放大芯片TLC271A,引入正反馈机制构建放大器电路。放大器具有前置放大和史密特触发器的整形功能,能够直接向用户的二次仪表输出标准方波信号。这种信号检出器灵敏度高、功耗低、结构紧凑、具有良好的抗震和抗干扰能力。采用这种信号检出器的涡轮流量计已经在石油企业应用达八年之久。     

Adaptive element-free Galerkin method applied to the limit analysis of plates

The implementation of an h-adaptive element-free Galerkin (EFG) method in the framework of limit analysis is described. The naturally conforming property of meshfree approximations (with no nodal connectivity required) facilitates the implementation of h-adaptivity. Nodes may be moved, discarded or introduced without the need for complex manipulation of the data structures involved. With the use of the Taylor expansion technique, the error in the computed displacement field and its derivatives can be estimated throughout the problem domain with high accuracy. A stabilized conforming nodal integration scheme is extended for use in error estimation and results in an efficient and truly meshfree adaptive method. To demonstrate its effectiveness the procedure is then applied to plates with various boundary conditions.     

Dual reciprocity boundary element method in Laplace domain applied to anisotropic dynamic crack problems

In this paper the dual reciprocity boundary element method in the Laplace domain for anisotropic dynamic fracture mechanic problems is presented. Crack problems are analyzed using the subregion technique. The dynamic stress intensity factors are computed using traction singular quarter-point elements positioned at the tip of the crack. Numerical inversion from the Laplace domain to the time domain is achieved by the Durbin method. Numerical examples of dynamic stress intensity factor evaluation are considered for symmetric and non-symmetric problems. The influence of the number of Laplace parameters and internal points in the solution is investigated.     

Development of a multiplier method for dynamic response optimization problems

The multiplier method is studied for optimum design of mechanical and structural systems subjected to dynamic loads. Certain key parameters in the algorithm are identified and extensive numerical experiments are conducted to see their effect on the performance of the method. Several mathematical programming problems, and static and dynamic response structural design problems are used to evaluate the method. Some new numerical procedures are proposed and evaluated to improve performance of the method. As a result of this study, a better understanding of the multiplier method has been achieved, and the effect of various parameters and procedures of the algorithm is better understood.Notation Number of equality constraints - COST Cost function value at the solution point - CPU Total CPU time on DN10000 - f(x) Cost function - g(x) Constraint vector of dimension m×1 - IFAIL Number of failed problems - A parameter used in the algorithm - L-BFGS Unconstrained minimization program that uses limited memory BFGS method - m Total number of constraints - n Number of design variables - v Number of degrees of freedom - NF Average number of function evaluations - NG Average number of gradient evaluations - NIT Average number of unconstrained minimizations - Parameter vector of dimension m×1 used in the definition of augmented Lagrange functional - r Penalty parameter vector of dimension m×1 - TRDDB Unconstrained minimization program that computes trust region step using the double dogleg method - u Lagrange multiplier vector of dimension m×1 - x Design variable vector of dimension n×1 - x _i Lower bound onx _i - x _ui Upper bound onx _i - (x) Augmented Lagrangian - P(x) Penalty function     

Development of principal component analysis applied to multitemporal Landsat TM data

Abstract

A method of extracting different crop information more effectively, by applying principal component analysis to a three-dimensional three-date Landsat TM data space, has been developed. Landsat TM data obtained on 7 June, 9 July and 26 August 1984 were used to examine the approach, and the results fully demonstrated its advantages over other methods of keeping classification accuracy without any calibrations for multitemporal Landsat data.     

Informetric analysis of dynamic decision rules in applied economic models: a selective survey

The characteristics of various information structures underlying a class of control theoretic applications to economic models known as linear decision rules are analysed here through a set of illustrative applications. The implications of departure from the two assumptions of normality and certainty equivalence are emphasized in particular, with reference to Cournot-type market models and stabilization policy in an econometric framework     

Adaptive genetic algorithms applied to dynamic multiobjective problems

This paper describes an adaptive genetic algorithm (AGA) with dynamic fitness function for multiobjective problems (MOPs) in a dynamic environment. In order to see performance of the algorithm, AGA was applied to two kinds of MOPs. Firstly, the algorithm was used to find an optimal force allocation for a combat simulation. The paper discusses four objectives that need to be optimized and presents a fuzzy inference system that forms an aggregation of the four objectives. A second fuzzy inference system is used to control the crossover and mutation rates based on statistics of the aggregate fitness. In addition to dynamic force allocation optimization problem, a simple example of a dynamic multiobjective optimization problem taken from Farina et al. [M. Farina, K. Deb, P. Amato, Dynamic multiobjective optimization problems: test cases, approximations, and applications, IEEE Trans. Evol. Comput. 8 (5) (2004) 425–442] is presented and solved with the proposed algorithm. The results obtained here indicate that performance of the fuzzy-augmented GA is better than a standard GA method in terms of improvement of convergence to solutions of dynamic MOPs.     

像素归一化方法在恶意代码可视分析中的应用

恶意代码的编写者通常采用自动化的手段开发恶意代码变种,使得恶意代码的数量呈现迅猛增长的态势。由于自动化的方式会重复利用恶意代码中的核心模块,因此也为病毒研究人员辨识和区分恶意代码族提供了有利依据。借鉴灰度图的思想,利用K-Nearest Neighbor（KNN）分类算法,给出了一种新的研究恶意代码谱系分类的可视化方法。其基本思想是,通过将二进制文件转换成双色通道的位图和像素归一图,从可视化的角度标识恶意样本特性,以此实现恶意代码族的相似度比较及分类。实验结果表明采用了像素归一化的降维映射机制能显著地减小文件可视特征的呈现时间开销,且该方法以自动化操作的方式运用Jaccard距离算法进行快速相似度比较,实现了恶意代码样本的有效分类,提高了分析人员的识别效率。     

基于动态概率主元分析的统计过程监测

概率主元分析(PPCA)已广泛应用于工业过程监测.然而,PPCA法仅构造了生产过程的静态线性关系,处理具有较强动态特性的实际工业生产过程效果较差.为此提出动态概率主元分析(DPPCA)法,对经过时谱扩展后的变量数据阵,通过期望最大化(EM)算法建立生成模型,从而将静态PPCA推广到动态多变量过程.最后将此法应用于TE过程的仿真研究,结果表明该法有效.     

Road-traffic monitoring by knowledge-driven static and dynamic image analysis

This article presents a visual application which allows a study and analysis of traffic behavior on major roads (more specifically freeways and highways), using as the main surveillance artefact a video camera mounted on a relatively high place (such as a bridge) with a significant image analysis field. The system described presents something new which is the combination of both traditional traffic monitoring systems, that is, monitoring to get information on different traffic parameters and monitoring to detect accidents automatically. Therefore, we present a system in charge of compiling information on different traffic parameters. It also has a surveillance module for that traffic, which can detect a wide range of the most significant incidents on a freeway or highway.     

A neuro-fuzzy method applied to the motors of a stereovision system

In this paper, a new approach for steering a binocular head is presented. This approach is based on extracting the expert's knowledge in order to improve the behaviour of the classical control strategies. This is carried out without inserting new elements in the system. Neuro-fuzzy techniques have been chosen in order to reach this target. As a result, a more friendly robotic system is achieved.     

Estimating sub-pixel components of a semi-arid woodland

Mixture models were applied to Landsat-MSS and -TM data in a semi-arid woodland in central western New South Wales, Australia to extract information on soil, herbage and tree cover. There was a significant correlation (r² = 0-71) between estimated and ground data for tree cover using the TM data, with a mean error of ± 143 per cent, and a mean error of ±11-2 per cent for the bare soil cover estimates. Only general trends were observed using the MSS data. The main areas of confusion were between senesced herbage and soil, and between green grass and the green leaves of trees.     

A visual query language for dynamic processes applied to a scenario driven environment

Query languages for multi-sensor data sources are generally dealing with spatial–temporal data that in many applications are of geographical type. Such applications are quite often concerned with dynamic activities where the collected sensor data are streaming in from multiple sensors. Data uncertainty is one of the most important issues, which the query language must deal with. Other aspects of concern are sensor data fusion but also association of multiple object observations. Demonstration of the dynamic aspects are generally difficult as scenarios in real-time cannot easily be set up, tested and run realistically. To overcome this problem the query language sigma query language (ΣQL) has been attached to a simulation framework. Together with this framework scenarios can be set up to form the basis for test and dynamic illustration of the query language. Eventually the query language can be used to support decision making as well. Within the simulation framework input data are coming from sensor models that eventually can be replaced by data from real sensors. Services can be integrated with the information system, used for various purposes and supported by the various capabilities of the query language. A consequence of this approach is that the information delivered by the services, including the query language, can be used as input to an operational picture that eventually can be used to demonstrate on-going dynamic processes. In this work, an extension to ΣQL, called VisualΣQL, will be discussed together with some other relevant services useful in dynamic situations as complements to the query language. Furthermore, the use of the system will be illustrated and discussed by means of a scenario that has been run in the simulation environment.