青藏高原地区被动微波遥感反演地表温度算法验证

近年来,青藏高原地区的水热平衡成为关注的焦点,而地表温度是陆表过程模型的重要输入参数之一。被动微波遥感在地表温度反演上已经取得了一些进展。本文重点用被动微波数据反演地表温度算法对青藏高原地区的数据做不同下垫面的地面验证和分析,包括Mao(2005)、Richard(2003)、Zhao(2011)3种算法。研究表明:Richard(2003)的单通道算法能够适应低矮植被地区,反演精度高;Zhao(2011)算法在裸土地区的反演精度更高;而Mao(2005)算法出现了低估的情况。研究发现3种算法的绝对误差随不同时间降雨的变化呈现相同的波动趋势,即反演精度受到降雨的影响,降雨量增大,温度反演误差变大;降雨之后,随着地表逐渐干燥,土壤水分逐渐减小,误差随之减小。     

Robust fuzzy control for continuous perturbed time‐delay affine takagi–sugeno fuzzy models

The stability analysis and controller synthesis methodology for a continuous perturbed time‐delay affine (CPTDA) Takagi–Sugeno (T‐S) fuzzy model is proposed in this paper. The CPTDA T‐S fuzzy models include both linear nominal parts and uncertain parameters in each fuzzy rule. The proposed fuzzy control approach is developed based on an iterative linear matrix inequality (ILMI) algorithm to cope with the stability criteria and H_∞ performance constraints for the CPTDA T‐S fuzzy models. Finally, a numerical simulation for the nonlinear inverted pendulum system is given to show the application and availability of the present design approach. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Scheduling jobs to consider physiological factors

We studied scheduling jobs and breaks for a single worker. The processing time of jobs increases as the worker tires. In this study, we assume that conventional machine scheduling models do not always work for humans. So, while determining the break time, we consider the workers' physiological factors. The two objectives considered are the total flow time and makespan. An exact mathematical model and heuristic algorithm are developed to solve large problems. Numerical examples are presented for understanding and analyzing the performance of the mathematical model and the heuristic. © 2011 Wiley Periodicals, Inc.     

Evolution computation based learning algorithms of polygonal fuzzy neural networks

We present two fuzzy conjugate gradient learning algorithms based on evolutionary algorithms for polygonal fuzzy neural networks (PFNN). First, we design a new algorithm, fuzzy conjugate algorithm based on genetic algorithm (GA). In the algorithm, we obtain an optimal learning constant η by GA and the experiment indicates the new algorithm always converges. Because the algorithm based on GA is a little slow in every iteration step, we propose to get the learning constant η by quantum genetic algorithm (QGA) in place of GA to decrease time spent in every iteration step. The PFNN tuned by the proposed learning algorithm is applied to approximation realization of fuzzy inference rules, and some experiments demonstrate the whole process. © 2011 Wiley Periodicals, Inc.     

基于机器学习的日志解析系统设计与实现

针对现有日志分类方法只适用于格式化的日志,且性能依赖于日志结构的问题,基于机器学习方法对日志信息解析算法LogSig进行了扩展改进,并设计开发了一个集数据处理与结果分析于一体的日志解析系统,包括原始数据预处理、日志解析、聚类分析评价、聚类结果散点图显示等功能,在VAST 2011挑战赛的开源防火墙日志数据集上进行了测试。实验结果表明,改进后的算法在归类整理日志事件时的平均准确性达到85%以上;与原LogSig算法相比,日志解析精度提高了50%,同时解析时间仅为原先的25%,可用于大数据环境下高效准确地对多源非结构化日志数据进行解析。     

Efficient Hausdorff Distance computation for freeform geometric models in close proximity

We present an interactive-speed algorithm for computing the Hausdorff Distance (HD) between two freeform geometric models represented with NURBS surfaces. The algorithm is based on an effective technique for matching a surface patch from one model to the corresponding nearby surface patch on the other model. To facilitate the matching procedure, we employ a bounding volume hierarchy (BVH) for freeform NURBS surfaces, which provides a hierarchy of Coons patches and bilinear surfaces approximating the NURBS surfaces (Kim et al., 2011 [1]). Comparing the local HD upper bound against a global HD lower bound, we can eliminate the majority of redundant surface patches from further consideration. The resulting algorithm and the associated data structures are considerably simpler than the previous BVH-based HD algorithms. As a result, we can compute the HD of two freeform geometric models efficiently and robustly even when the two models are in close proximity. We demonstrate the effectiveness of our approach using several experimental results.     

Web服务选择与匹配的应用现状研究

首先对Web服务的概念、结构进行简单的介绍,其次讨论了关于Web服务不确定性的研究现状,然后对Web服务选择与匹配的研究现状进行了深入的分析。最后结合现有的研究现状进行了分析和讨论。同时,还给出了相关算法复杂性影响因子,由于涉及到的匹配算法和模型较多,所以对研究中找到的匹配算法和模型进行了归类分析。     

没yWeb服务选择与匹配的应用现状研究

首先对Web服务的概念、结构进行简单的介绍,其次讨论了关于Web服务不确定性的研究现状,然后对Web服务选择与匹配的研究现状进行了深入的分析。最后结合现有的研究现状进行了分析和讨论。同时,还给出了相关算法复杂性影响因子,由于涉及到的匹配算法和模型较多,所以对研究中找到的匹配算法和模型进行了归类分析。     

面向铝挤压的作业排产优化

在深入研究铝挤压生产特点的基础上,以最小化加工总流经时间（total flow time,TFT）为目标建立了两类铝挤压作业排产优化模型,采用改进的人工蜜蜂群算法对其求解．该算法根据铝挤压排产问题的特点重新设计了解的表达与新解的产生方式．仿真实验结果表明,提出的方法能够有效减少产品加工的总流经时间．     

Certification validation: Back to the past

In MBarka and Stern (2011) [3], we proposed a new algorithm to validate certificates in the past with the goals of it being simple to present, simple to implement and to fall back on standard algorithms with current time settings. This paper improves our algorithm through a much cleaner handling of time issues by defining a new notion, called revocation freshness, yielding a better fall-back on the standard algorithm. It also takes into account a practical “caution period” to lessen some of our previous hypothesis.     

Predicting Chaotic Time Series Using Neural and Neurofuzzy Models: A Comparative Study

The prediction accuracy and generalization ability of neural/neurofuzzy models for chaotic time series prediction highly depends on employed network model as well as learning algorithm. In this study, several neural and neurofuzzy models with different learning algorithms are examined for prediction of several benchmark chaotic systems and time series. The prediction performance of locally linear neurofuzzy models with recently developed Locally Linear Model Tree (LoLiMoT) learning algorithm is compared with that of Radial Basis Function (RBF) neural network with Orthogonal Least Squares (OLS) learning algorithm, MultiLayer Perceptron neural network with error back-propagation learning algorithm, and Adaptive Network based Fuzzy Inference System. Particularly, cross validation techniques based on the evaluation of error indices on multiple validation sets is utilized to optimize the number of neurons and to prevent over fitting in the incremental learning algorithms. To make a fair comparison between neural and neurofuzzy models, they are compared at their best structure based on their prediction accuracy, generalization, and computational complexity. The experiments are basically designed to analyze the generalization capability and accuracy of the learning techniques when dealing with limited number of training samples from deterministic chaotic time series, but the effect of noise on the performance of the techniques is also considered. Various chaotic systems and time series including Lorenz system, Mackey-Glass chaotic equation, Henon map, AE geomagnetic activity index, and sunspot numbers are examined as case studies. The obtained results indicate the superior performance of incremental learning algorithms and their respective networks, such as, OLS for RBF network and LoLiMoT for locally linear neurofuzzy model.     

基于二元与三元模型相结合的句法规则层次化分析算法

句法分析是自然语言处理领域中应用前景非常广阔的一个研究方向.针对目前句法分析多数是从字、词的角度出发且存在诸多不足,提出了二、三元词模型相结合的句法规则层次化分析算法,并结合分词、词性标注以及句子组织信息之间的结合度来解决词元间优先合成的问题,同时利用句子成分之间的语法结构关系对词性、词序的影响,实现句法规则的层次化分...     

基于UML的卫星网路由算法仿真系统研究

本文首先介绍了我们提出的基于时空的路由算法思想，然后用UML(Unified Modeling Language)对基于该算法的仿真系统(Satellite Network Simulation based on Space Time，STSNS)进行建模。在仿真建模过程中，首先用用例(use case)对仿真系统的需求进行了分析，然后建立了STSNS的静态模型和动态模型，并用UML中相应的图例来描述。最后给出了STSNS的详细实现技术。STSNS能对基于时空的路由算法进行很好的仿真，仿真的结果表明，基于时空的路由算法能很好地满足卫星网路由的要求。     

A percentile system optimization approach with and without path enumeration

In this paper we deal with the travel time reliability PUE (probabilistic user equilibrium) problem studied by Lo et al. (2006) [12] and Nie (2011) [15] and we propose an alternative model that assumes a location-scale family for the path travel times, whose means and variances are evaluated in terms of link travel times. This avoids the use of the central limit theorem and convolutions providing a flexible and simple alternative. Contrary to the most existing models that require path enumeration or an iterative method to add paths sequentially, we present a percentile system optimization in its two versions: with and without path enumeration. Two examples of applications, one of them real, are used to illustrate the power of the proposed method. The cpu times required to solve the problem seem reasonable. In addition, we answer an open question raised by Nie (2011) [15] about the permutability of percentiles and partial derivatives of route travel times with respect to route flows. A family of counterexamples is given to demonstrate that the two operations: (a) obtain percentiles and (b) partial derivation of route travel times do not commute. Finally, to reproduce the trial-and-error sequence followed by users when selecting paths, we also present an algorithm that simulates this iterative process and shows that the final long-term user behavior coincides with PUE (probabilistic user equilibrium) problem resulting from some existing models.     

Age structured populations with history dependent mortality and natality

We consider a modification of the Gurtin-MacCamy model of population dynamics, where the birth and death moduli depend on a time integral of the solution rather than on an age integral. This models the influence of past history in the time dependence of the death and birth rates. We propose a numerical algorithm to approximate the solution based on the finite difference method of characteristics and prove that it is optimally convergent. The algorithm is devised to minimize the storage requirement in the time variable.     

Three‐dimensional thinning algorithms on graphics processing units and multicore CPUs

Three‐dimensional curve skeletons are a very compact representation of three‐dimensional objects with many uses and applications in fields such as computer graphics, computer vision, and medical imaging. An important problem is that the calculation of the skeleton is a very time‐consuming process. Thinning is a widely used technique for calculating the curve skeleton because of the properties it ensures and the ease of implementation. In this paper, we present parallel versions of a thinning algorithm for efficient implementation in both graphics processing units and multicore CPUs. The parallel programming models used in our implementations are Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL). The speedup achieved with the optimized parallel algorithms for the graphics processing unit achieves 106.24x against the CPU single‐process version and more than 19x over the CPU multithreaded version. Copyright © 2011 John Wiley & Sons, Ltd.     

基于改进的背景差分的运动目标实时检测算法

针对传统混合高斯建模算法计算量过大与目标轮廓清晰度小的问题,提出了一种新的运动目标实时检测算法。该算法引入三帧差分的方法,提高了检测目标轮廓的清晰度;通过HSI混合高斯建模前进行分块处理有效减小了计算量,因此算法的实时性有了明显的改善;并利用逻辑运算融合三帧差分与HSI混合高斯模型进行高效的背景提取;最后运用数学形态学方法进一步优化检测结果。实验结果表明,相比混合高斯模型经典算法,该算法能更快速、更准确地检测出智能监控视频序列中的运动目标,并且目标轮廓清晰度也有明显的改善。     

On algorithmic analysis of transcriptional regulation by LTL model checking

Studies of cells in silico can greatly reduce the need for expensive and prolonged laboratory experimentation. The use of model checking for the analysis of biological networks has attracted much attention recently. The practical limitations are still the size of the model, and the time needed to generate the state space. This paper is focused on the model checking approach for analysis of piecewise-linear deterministic models of genetic regulatory networks. Firstly, the qualitative simulation algorithm of de Jong et al. that builds the heart of Genetic Network Analyzer (GNA) is revisited and its time complexity is studied in detail. Secondly, a novel algorithm that reduces the state space generation time is introduced. The new algorithm is developed as an abstraction of the original GNA algorithm. Finally, a fragment of linear time temporal logic for which the provided abstraction is conservative is identified. Efficiency of the new algorithm when implemented in the parallel model checking environment is demonstrated on a set of experiments performed on randomly modified biological models. In general, the achieved results bring a new insight into the field of qualitative simulation emerging in the context of systems biology.     

Lookup table control method for vibration suppression of a flexible manipulator with optimization of the minimum settling time and energy consumption

Active vibration suppression of flexible manipulators is important in many engineering applications, such as robot manipulators and high‐speed flexible mechanisms. The demand for a short settling time and low energy consumption of vibration suppression requires consideration of optimal control. Under a wide range of operating conditions, however, the fixed optimal parameters determined for a control algorithm might not produce the best performance. Therefore, to enhance performance, this paper suggests a lookup table control method for a flexible manipulator. This method can tune itself to the optimal parameters on the basis of initial maximum responses to the controlled system. In this study, a multi‐objective genetic algorithm is used to search for optimal parameters with regard to positive position feedback to the control algorithm. In turn, with the optimal parameters, the multi‐objective functions of the settling time and energy consumption during the vibration control of a flexible manipulator can be minimized. The simulation and experimental results both indicate that the energy consumption can be reduced significantly if the settling time is slightly increased. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于隐马尔可夫模型和免疫粒子群优化的多序列比对算法

序列的多重比对是生物序列分析研究中的一个重要内容．基于免疫系统的疫苗接种和受体编辑模型,结合粒子群优化方法提出了一种免疫粒子群优化算法,将该算法用于隐马尔可夫模型的学习过程,进而构建了一种基于隐马尔可夫模型和免疫粒子群优化的多序列比对算法,从BAliBASE比对数据库中选取了一些比对例子进行了模拟计算,并与Baum-Welch算法进行了比较．结果表明,所提出的方法不仅提高了比对的准确程度,而且缩减了比对所花费的时间。