相似理论在机床运动平稳性分析中的应用与研究

摩擦自激振动微分方程因其非线性不能求解，故文中提出运用模型试验和相似理论分析机床的低速运动平稳性，导出了表征导轨爬行现象的相似准则关系曲线，并通过实例对其进行了验证和推广。     

机床主轴相似设计方法的研究

提出了运用相似理论优化设计机床主轴及轴承的设计方法，并用实例对该方法进行了验证。     

Computing Minimum Area Homologies

Calculating and categorizing the similarity of curves is a fundamental problem which has generated much recent interest. However, to date there are no implementations of these algorithms for curves on surfaces with provable guarantees on the quality of the measure. In this paper, we present a similarity measure for any two cycles that are homologous, where we calculate the minimum area of any homology (or connected bounding chain) between the two cycles. The minimum area homology exists for broader classes of cycles than previous measures which are based on homotopy. It is also much easier to compute than previously defined measures, yielding an efficient implementation that is based on linear algebra tools. We demonstrate our algorithm on a range of inputs, showing examples which highlight the feasibility of this similarity measure.     

基于Haar型LBP纹理特征的人体姿态估计

基于人体部件的树形模型表达直观且计算高效,被广泛应用在人体姿态估计中。然而模型本身在部件特征表达上的不足限制了姿态估计结果的准确度,为此,提出一种基于图结构模型和新型纹理特征的人体姿态估计算法。采用改进后的外观模型,从训练集中获得部件位置的先验知识,联系相邻部件之间的关系,并将其应用于测试图像的外观模型建模阶段。应用Haar型局部二值模式( HLBP )纹理特征,提取部件的纹理信息,对图像进行分块处理,并为每一块赋予不同的权重。实验结果表明,带权重的HLBP特征能更有效地提取部件的纹理特征,与HLBP特征、归一化HLBP特征和颜色特征相比能获得更高的准确度。     

半监督中文事件抽取中的模板过滤和转换方法

事件模板是指导事件抽取工作的依据,半监督方法下模板的准确性显得尤为重要.目前,基于双视图的“触发词-论元”模板的中文信息事件抽取系统不能有效地解决触发词一词多义的现象和模板稀疏现象.提出了一种借助论元进行触发词语义消歧的方法,并利用该方法进行模板过滤以消除无效模板的影响.另外,针对几种特殊的中文句型,根据句法结构提出了模板转换规则,从而提高了模板的适用性.在ACE2005中文语料上的测试表明,该方法可有效地提高半监督中文信息事件抽取系统的性能.     

分块二维局部保持鉴别分析在人脸识别中的应用

局部保持鉴别分析在人脸识别研究中具有非常重要的地位。在此基础上提出的2DLPDA算法直接在二维空间进行运算,一定程度上提高了性能。但是当样本在光照阴影、遮挡等情况下时,识别率受到很大影响,为此提出一种改进的算法,即分块二维局部保持鉴别分析方法。其将样本分块,以更好地提取样本中的局部近邻特征。这样同一样本的不同分块在选择近邻时,就可能具有来自不同样本的近邻,从而能更好地提取样本的局部特征。最后将局部特征整合为整体作为识别的依据。在AR、YALE及ORL库上验证了算法的有效性。     

Security optimal power flow considering loading margin stability using hybrid FFA–PS assisted with brainstorming rules

This paper presents a new power system planning strategy which combines firefly algorithm (FFA) with pattern search algorithm (PS). The purpose is minimizing total fuel cost, total power loss and reducing total voltage deviation, with the objective of enhancing the loading margin stability and consequently the power system security. A new interactive and simple mechanism, inspired in brainstorming process, is proposed that allows FFA and PS algorithms to explore new regions of the search space. In this study the Static VAR compensator (SVC) is modeled and integrated in an efficient location which is chosen considering the voltage stability index. The proposed algorithm is interactive and tries to optimize a set of control variables at the same time, namely, active power generations, voltage of generators, tap transformers, and the reactive power of shunt compensators to optimize three objective functions such as: fuel cost, total power loss and total voltage deviation. These variables are optimized using a flexible interactive and competitive search mechanism. The proposed planning strategy has been examined and applied to two practical test systems IEEE 14-Bus and IEEE 30-Bus. Simulation results confirm the effectiveness of this hybrid strategy for solving the security optimal power flow.     

Towards high accuracy calibration of electron backscatter diffraction systems

For precise orientation and strain measurements, advanced Electron Backscatter Diffraction (EBSD) techniques require both accurate calibration and reproducible measurement of the system geometry. In many cases the pattern centre (PC) needs to be determined to sub-pixel accuracy. The mechanical insertion/retraction, through the Scanning Electron Microscope (SEM) chamber wall, of the electron sensitive part of modern EBSD detectors also causes alignment and positioning problems and requires frequent monitoring of the PC. Optical alignment and lens distortion issues within the scintillator, lens and charge-coupled device (CCD) camera combination of an EBSD detector need accurate measurement for each individual EBSD system.This paper highlights and quantifies these issues and demonstrates the determination of the pattern centre using a novel shadow-casting technique with a precision of ∼10 μm or ∼1/3 CCD pixel.     

A metamodeling approach for pattern specification and management

The formal specification of design patterns is central to pattern research and is the foundation of solving various pattern-related problems.In this paper,we propose a metamodeling approach for pattern specification,in which a pattern is modeled as a meta-level class and its participants are meta-level references.Instead of defining a new metamodel,we reuse the Unified Modeling Language(UML)metamodel and incorporate the concepts of Variable and Set into our approach,which are unavailable in the UML but essential for pattern specification.Our approach provides straightforward solutions for pattern-related problems,such as pattern instantiation,evolution,and implementation.By integrating the solutions into a single framework,we can construct a pattern management system,in which patterns can be instantiated,evolved,and implemented in a correct and manageable way.     

基于Snort系统的网络入侵检测模型的研究

网络入侵检测是网络安全领域研究的热点问题,通过应用分组交换检测机制和Markov链,提出基于Snort系统的IDS模型,设计Snort系统规则库和检测引擎。分析结果表明,改进模型和方法可以提高网络入侵检测中海量数据的检测准确率和效率。