基于解开操作的直角多边形随机生成算法

集成电路物理设计的测试需随机生成直角多边形以覆盖所有的情况。基于此,提出一种基于解开操作的直角多边形随机生成算法,可应用于超大规模集成电路物理设计算法的测试和分析。该算法随机生成一个点序列,逐一将每对相交的线段解开,直至找不到任何相交线段。对该算法的有穷性作出证明,并以实验证明该算法简单有效。     

基于语义模式的英语动词汉译

英语动词正确汉译是机器翻译的难点.为此,提出一种基于动词语义模式库、固定句式库和变量库的英语动词汉译算法.介绍语义模式的提取方法,构建常用动词的语义模式库、固定句式库和变量库,归纳动词语义模式的3种结构形式:V语义模式,VO相邻语义模式和VO非相邻语义模式.动词语义模式库由上述3种结构形式对应的模式库构成.实验结果表明...     

面向轨迹数据流的KNN近似查询

提出一种基于滑动窗口的K-最近邻(KNN)近似查询算法。将滑动窗口内数据通过聚类划分成若干大小不一的基本窗口,针对每个基本窗口给定一个采样率,对窗口内数据进行偏倚采样,形成数据流摘要,并基于该摘要,采用计算几何平面扫描算法执行分布式最近邻查询。仿真实验结果表明该算法有效,且具有较好的可扩展性。     

基于骨架关节点约束的交互式局部变形

利用广义元球变形技术,提出一种基于骨架关节点约束的交互式局部变形方法。该方法提取多边形网格模型的骨架关节点并结合模型骨架图结构确定骨架关节点对应的局部区域,计算三维网格点到骨架节点的欧式距离,将约束区域的最大欧氏距离作为约束半径,得到各骨架节点对应的势函数值,通过控制骨架节点的空间位置给出三角形面片点的新坐标位置。实验结果表明,该方法有效保持多边形网络模型的局部特征,并确保了模型变形的直观性和高效性。     

新型云计算服务器的设计与实现

采用传统服务器组成云计算数据中心存在体积大、功耗高、效能低等问题。为此,设计并实现一种新型云计算服务器。对该服务器的关键技术进行阐述,包括云处理器、3D-torus网络拓扑结构、负载均衡策略、硬件虚拟化等技术。与传统服务器相比,该新型云计算服务器具有体积较小、功耗低等特点。     

一种改进的Harris特征点检测算法

现有Harris特征点检测算法采用高斯滤波进行平滑,图像存在角点信息丢失与偏移的现象。为解决该问题,提出基于变分B样条滤波与快速局部窗口搜索相结合的Harris特征点检测算法,选择具有低通特性的B样条函数作为平滑函数构造滤波器,引入形态学滤波中的极大值滤波思想,利用快速局部窗口搜索算法进行特征点局部极值的提取,从而提高特征点提取的精度和速度。实验结果表明,改进算法具有特征点提取快速均匀、检测定位准确、抑噪性好的特点。     

A heuristic approach for packing identical rectangles in convex regions

In this paper we propose a heuristic approach for the problem of packing equal rectangles within a convex region. The approach is based on an Iterated Local Search scheme, in which the key step is the perturbation move. Different perturbation moves, both combinatorial and continuous ones, are proposed and compared through extensive computational experiments on a set of test instances. The overall results are quite encouraging.     

On properties not inherited by monoids from their Schützenberger groups

We give an example of a monoid with finitely many left and right ideals, all of whose Schützenberger groups are presentable by finite complete rewriting systems, and so each have finite derivation type, but such that the monoid itself does not have finite derivation type, and therefore does not admit a presentation by a finite complete rewriting system. The example also serves as a counterexample to several other natural questions regarding complete rewriting systems and finite derivation type. Specifically it allows us to construct two finitely generated monoids M and N with isometric Cayley graphs, where N has finite derivation type (respectively, admits a presentation by a finite complete rewriting system) but M does not. This contrasts with the case of finitely generated groups for which finite derivation type is known to be a quasi-isometry invariant. The same example is also used to show that neither of these two properties is preserved under finite Green index extensions.     

M-estimator with asymmetric influence function for estimating the Burr type III parameters with outliers

The Burr type III distribution allows for a wider region for the skewness and kurtosis plane, which covers several distributions including the log-logistic, and the Weibull and Burr type XII distributions. However, outliers may occur in the data set. The robust regression method such as an M-estimator with symmetric influence function has been successfully used to diminish the effect of outliers on statistical inference. However, when the data distribution is asymmetric, these methods yield biased estimators. We present an M-estimator with asymmetric influence function (AM-estimator) based on the quantile function of the Burr type III distribution to estimate the parameters for complete data with outliers. The simulation results show that the M-estimator with asymmetric influence function generally outperforms the maximum likelihood and traditional M-estimator methods in terms of the bias and root mean square errors. One real example is used to demonstrate the performance of our proposed method.     

Further results of recursive evaluation for compound distribution with the severity distribution of mixed type

Yang et al. [J.P. Yang, S.H. Cheng, Q. Wu, Recursive equations for compound distribution with the severity distribution of the mixed type, Science in China Series A 48 (2005) 594-609] investigated a recursive procedure for a kind of compound distributions with the number of claims belonging to (a,b)-family and the severity distribution of the mixed type. In this paper, we extend their results by assuming that the claim number belongs to a larger class. As applications, the excess-of-loss reinsurance treaty is discussed and concrete examples are considered in some detail.