The subspace global skyline query processing over dynamic databases

The global skyline, as an important variant of the skyline, has been widely applied in multi-criteria decision making, business planning and data mining. In this paper, we extend our early work and propose the maintenance methods to process the subspace global skyline (SGS) queries in dynamic databases. In the previous work, we proposed the index structure RB-tree, which can effectively manage the data to accelerate the subspace global skyline calculation. Also, the basic single SGS algorithm based on RB-tree (SSRB) and the optimized single SGS algorithm (OSSRB) were proposed to process a single SGS query. In addition, the multiple SGS algorithm (MSRB) was proposed to calculate multiple SGS queries by sharing the scan spaces of different queries. In this paper, we design some data structures and propose the maintenance approaches of SSRB, OSSRB and MSRB to cope with updates that happen to data sets. Thus our extended algorithms can be adopted for dynamic data sets. Finally, the experimental results show that the proposed algorithms OSSRB and MSRB have good performance to process SGS queries and they can be easily maintained with dynamic datasets.     

Event‐Triggered Control for Couple‐Group Multi‐Agent Systems with Logarithmic Quantizers and Communication Delays

This paper mainly investigates the event‐triggered control for couple‐group multi‐agent systems with communication delay. Logarithmic quantization is considered in the communication channels. Event‐triggered control laws are adopted to reduce the frequency of individual actuation updating for discrete‐time agent dynamics. The proposed protocol is efficient as long as the quantization levels are dense enough, i.e. the density of quantization levels goes to infinity is a sufficient condition for the asymptotic consensus of the multi‐agent systems. It turns out that the bounded consensus depends on not only the density of quantization levels, but also the updating strategy of events. Finally, a simulation example is given to demonstrate the effectiveness of the proposed methods.     

Dynamic behaviour of a magnetically actuated floating liquid marble

This paper reports the dynamic behaviour of a magnetically actuated floating liquid marble by analysing the oscillation of the marble. A liquid marble is a liquid droplet coated with hydrophobic powder. Magnetite particles inside the marble make it magnetic. The marble floats on a carrier liquid that contains aqueous glycerol of various concentrations. A permanent magnet located under the carrier liquid drives the floating marble with the initial velocity. Stopping the magnet abruptly causes the marble to oscillate around its final position for a few seconds. The oscillation was recorded and analysed using customised image processing and evaluation software. The damped harmonic motion model was then applied to the data and tested. Subsequently, critical parameters of the system such as the initial displacement, friction correction factor, the apparent frequency and the spring constant were determined and discussed. The simple experimental set-up and convenient theoretical approach allow us to characterise the marble motion under the influence of a magnet with good accuracy.     

Externalizing cognitive maps via map reconstruction and verbal description

Universal Access in the Information Society - Helping blind people to build cognitive maps of an environment is one of the aims of several assistive systems. In order to evaluate such assistive...     

统计算法选择对统计模型检测效率的影响分析

近年来,统计模型检测技术已经得到了广泛的应用,不同的统计算法对统计模型检测的性能有所影响。主要对比不同统计算法对统计模型检测的时间开销影响,从而分析算法的适用环境。选择的统计算法包括切诺夫算法、序贯算法、智能概率估计算法、智能假设检验算法及蒙特卡罗算法。采用无线局域网协议验证和哲学家就餐问题的状态可达性验证为实例进行分析,使用PLASMA模型检测工具进行验证。实验结果表明,不同的统计算法在不同的环境中对模型检测的效率有不同的影响。序贯算法适用于状态可达性性质的验证,时间性能最优;智能假设检验算法与蒙特卡罗算法适合验证复杂模型。这一结论有助于在模型检测时对统计算法的选择,从而提高模型检测的效率。     

功能需求到测试用例的可追溯性研究

软件开发主要由需求收集、设计、实现、测试和维护等几个阶段构成,其中维护始终是主要开销。在维护阶段,开发人员必须理解程序才能定位缺陷,而系统的需求和源代码、测试用例等之间的可追溯性连接能帮助减少开发人员在理解程序时的工作量。研究现有的功能定位技术和可追溯性方法,通过对现有方法的改进,提出了一种集成动态执行信息和IR技术的方案来建立需求到测试用例的可追溯性连接,用以辅助开发人员在维护阶段的工作。     

基于分层Agent的军事分析仿真在线辅助决策系统研究

指挥与控制是军事分析仿真在线辅助决策系统中研究的主要对象之一。通过分层Agent方法对军事分析仿真在线辅助决策系统的指控关系进行建模,将战役级仿真中的指挥和控制划分成战略层、战术层和执行层,并对各层Agent功能进行描述。系统采用基于BOM组件的高性能RTI仿真方法,最后以一个空地攻防对抗系统的实例说明了该建模方法的应用。     

基于粒子滤波和过程模型的动态数据校正

针对所有的基于粒子滤波的动态数据校正中粒子滤波方法仅仅是针对数据的,本文提出了一种基于粒子滤波和过程模型的动态数据校正方法(DDRPFPM)。该方法将过程模型引入到动态数据校正中,作为约束条件来更新粒子的权值,有效提高了粒子的信任度,解决了基于粒子滤波的动态数据校正(DDRPF)过程中存在的粒子退化问题。通过CSTR仿真证明,DDRPFPM能够较好的应用于动态数据校正,与DDRPF相比无论是对温度噪声还是离群值都有更强的校正能力。     

改进的局部保持投影算法的多模型软测量

针对化工生产过程中软测量模型估计精度的问题,提出一种基于改进的局部保持投影算法的多模型建模方法。该方法通过有监督自适应权值的局部保持投影算法对输入数据空间进行特征提取,并结合最近邻分类器算法进行输入空间的划分,最后融合支持向量机实现多模型建模。仿真应用结果表明:将改进的局部保持投影算法应用在UCI数据库的Iris数据集的分类中,其分类精度高于基本的局部保持投影算法的分类精度;同时将改进的局部保持投影算法的多模型建模方法应用于双酚A生产的软测量多模型建模中,该方法能够有效的进行输入空间地划分,构建回归模型的数据更加合理,使得模型估计精度得到了提高,并具有更强的泛化能力。     

热工通用多通道微机数据采集和自动控制系统

介绍了一种适用于热工领域的微机通用数据采集和自动控制系统。文章阐述了该系统硬件和软件的框架结构,同时分析了系统的进行了试验,总体效果很好,尤其是带有帮助系统的可视化操作软件令用户使用起来十发方便。