Finding Largest Subtrees and Smallest Supertrees

As trees are used in a wide variety of application areas, the comparison of trees arises in many guises. Here we consider two generalizations of classical tree pattern matching, which consists of determining if one tree is isomorphic to a subgraph of another. For the embedding problems of subgraph isomorphism and topological embedding, we present algorithms for determining a largest tree embeddable in two trees T and T' (or a largest subtree) and a smallest tree in which each of T and T' can be embedded (or a smallest supertree). Both subtrees and supertrees can be used in a variety of different applications. For example, when each of the two trees contains partial information about a data set, such as the evolution of a set of species, the subtree or supertree corresponds to a structuring of the data in a manner consistent with both original trees. The size of a subtree or supertree of two trees can also be used to measure the similarity between two arrangements of data, whether images, documents, or RNA secondary structures. In this paper we present a general paradigm for sequential and parallel subtree and supertree algorithms for subgraph isomorphism and topological embedding. Our sequential algorithms run in time O(n ^2.5 log n) and our parallel algorithms in time O(log ³ n) on a randomized crew pram using a polynomial number of processors. In addition, we produce better algorithms for these problems when the underlying trees are ordered, that is, when the children of each node have a left-to-right ordering associated with them. In particular, we obtain O(n ² ) -time sequential algorithms and O(log ³ n) -time deterministic parallel algorithms on crew prams for both embeddings. Received July 17, 1995; revised May 25, 1996, and December 10, 1996.     

C＆C08交换机最小单元的组建及在实际工作中的应用

宣钢公司使用华为C＆C08数字程控电话交换机进行生产和经营的电话通信，为使维护人员对该设备能更深入地了解学习，建立一个交换机的最小单元，并可利用其进行设备维护学习、通信新业务自主开发等工作。     

基于“JavaBean可视化组件”的开发技术的探究

JavaBean是一种专门为当前软件开发者设计的全新的可视化组件技术,它为软件开发者提供了一种极佳的问题解决方案。该文描述了用JavaBean开发可视化组件的相关技术。通过阐明了可视化编程的原理和过程,引入Java语言的JavaBean技术来进一步说明JavaBean技术在开发可视化组件的机制和优势,尤其是介绍了JavaBean能够被应用程序开发工具侦测其属性和事件的能力。     

基于最小二乘支持向量机的土壤含水量检测的研究与分析

介绍了一种基于最小二乘支持向量机的方法来实现土壤含水量的检测,实验结果证明该方法有效、可行,并具有一定的实用价值。     

Exact observability and exponential stability of infinite-dimensional bilinear systems

This paper deals with exact observability and stability for a class of infinite-dimensional bilinear systems. First we show that the bilinear systems are exactly observable for any positive bounded input signal. Second we prove that given such an input signal the open-loop bilinear systems (or time-varying linear systems) are exponentially stable. A strong motivation of our study comes from chemical engineering processes described by partial differential equations.     

On the mean random inconsistency index of analytic hierarchy process (AHP)

In this paper, we find a closed-form expression for the largest eigenvalue of a three-dimensional random pairwise comparison matrix. This expression can give us all the corresponding distribution moments. In particular, the exact value of the mean and variance of the largest eigenvalue associated a three-dimensional random pairwise comparison matrix are calculated, and are compared with those obtained by others on the topic. For n = 4 to 15, the mean and variance are determined by simulation. The number of simulation runs are determined by taking both the absolute and the relative simulation errors into the consideration.     

Fast and Robust Approximation of Smallest Enclosing Balls in Arbitrary Dimensions

In this paper, an algorithm is introduced that computes an arbitrarily fine approximation of the smallest enclosing ball of a point set in any dimension. This operation is important in, for example, classification, clustering, and data mining. The algorithm is very simple to implement, gives reliable results, and gracefully handles large problem instances in low and high dimensions, as confirmed by both theoretical arguments and empirical evaluation. For example, using a CPU with eight cores, it takes less than two seconds to compute a 1.001‐approximation of the smallest enclosing ball of one million points uniformly distributed in a hypercube in dimension 200. Furthermore, the presented approach extends to a more general class of input objects, such as ball sets.     

长期施肥对旱地土壤有机磷及其组分的影响

通过15年长期定位试验,采用Bowman和Cole提出的土壤有机磷分级方法,研究了不同耕作施肥措施对旱地耕层土壤有机磷及其组分的影响。结果显示旱地土壤各个处理的活性有机磷含量低,占有机磷总量的比例低于3.6%,中活性有机磷为有机磷的主体,约占有机磷总量的73.37%-91.54%。休闲、撂荒及磷肥与其它肥料配合使用,均增加了耕层土壤的中活性有机磷含量,增加了中稳性有机磷含量及其比重;休闲、撂荒及磷钾提高了高稳性有机磷含量及比重,而氮磷钾及其与有机肥配合处理则降低了高稳性有机磷的含量。尽管不同耕作施肥管理均影响旱地土壤有机磷含量,但是施用有机肥对有机磷的增加贡献最大;撂荒与休闲相比,前者更有利于土壤有机磷的积累。     

Texture Synthesis using Exact Neighborhood Matching

In this paper we present an elegant pixel‐based texture synthesis technique that is able to generate visually pleasing results from source textures of both stochastic and structured nature. Inspired by the observation that the most common artifacts that occur when synthesizing textures are high‐frequency discontinuities, our technique tries to avoid these artifacts by forcing at least one of the direct neighboring pixels in each causal neighborhood to match within a predetermined threshold. This does not only avoid deterioration of the visual quality, but also results in faster synthesis timings. We demonstrate our technique on a variety of stochastic and structured textures.     

基于DC和AC分量的二维数字水印算法

提出一种新的二维数字水印算法,该算法先把原始图像分块DCT,再对水印图像分块DCT,取每一图像块的直流系数和前12个DCT低频交流系数,分别构成水印信号的直流分量和交流分量。利用能量比确定各个子块的直流拉伸因子和交流拉伸因子。水印信号的直、交流分量以不同的能量分别嵌入到原始图像块DCT域的DC分量和AC分量中。实验结果表明,该算法具有良好的不可见性和稳健性。     

Windows脚本部件技术研究与应用

介绍了脚本部件的工作原理、特性以及使用脚本部件的一般步骤 ,指出利用脚本部件创建小巧高效、易于维护和部署的COM部件在工程应用中的意义 ,并给出了利用VisualBasic语言调用脚本部件的应用实例     

嵌入式典型零部件快速设计系统

研究运行于多种三维CAD平台下的嵌入式典型零部件设计系统的组件体系结构,提出基于用户自定义特征的典型零部件数据库设计和模板生成方法,开发了常用的7大类典型零部件设计与校核工具包,实现了CAD平台下典型零部件的模板生成与参数化重构、设计过程导航以及零部件之间基于坐标系的自动装配．最后给出Pro／Engineer2001下嵌入式典型零部件设计系统的运行实例,验证了该系统实现典型零部件从设计到三维造型乃至自动装配过程的一体化、快速化与智能化．     

构件仓库的研究与应用

为了解决构件的使用和管理问题,提出构件仓库的解决方案。首先,研究了构件仓库的总体结构和逻辑结构,从整体上分析构件仓库。其次,介绍了构件仓库的部署。最后,从构件使用、构件发布、构件管理和仓库设置四个方面研究了构件仓库的应用。对构件仓库的使用,根据用户角色的不同分别赋予不同的权限,合理地对构件仓库中的构件进行管理。采用构件仓库管理构件,可以有效地提高软件开发的效率,使构件能够更合理地得到复用,提高构件的复用率。实践表明,构件仓库能够有效地解决构件的使用和管理问题,为软件开发提供有力支持。     

空育131高产群体的产量构成和分蘖利用

以黑龙江省栽培面积最大的水稻品种空育131为对象,利用不同的肥密处理方式,创造结构和产量不同的群体。结果表明熏空育131产量构成要素中熏对产量直接贡献最大的是单位面积穗数熏其次是每穗粒数,8000kg·hm-2以上产量水平的穗粒结构为每平方米620～660穗和每穗60～65粒,结实率和千粒重对产量也有一定贡献。分蘖成穗率高、分蘖穗比率大的群体产量较高。     

基于行为的构件组合及存在性检查

多个构件的组合可以解决单个构件的行为不能完全满足用户需求的问题。构件组合的关键是检查组合后复合构件的行为是否完全满足用户的需求。针对上述问题,提出一个基于行为的构件组合方法。该方法采用具有终止状态的接口自动机描述构件行为和用户需求。为了检查组合后复合构件的行为是否满足用户需求,提出基于行为映射图的组合存在性检查方法,给出从复合构件中提取用户所需行为的方法。     

舰船微电子器件进货检验方案及流程浅析

文章介绍了用于舰船设备的微电子器件现状,包括类型、质量等级、用途等,并简要分析所生产的船用设备中的微电子器件的质量状况,以此为前提并根据船用设备的特点,浅析微电子器件的进货检验方案,并论述进货检验中各个流程的目的,以及改进措施。     

理想材料零件CAD/CAM中的数据格式及切片算法研究

为实现由均质材料、复合材料、功能梯度材料和功能细结构构成的理想材料零件的数字化设计制造，从非线性问题线性化角度考虑，针对理想材料零件数字化设计制造中的数据格式和切片算法问题，提出了基于三维几何实体单纯剖分的数据格式。以统一、简便的形式、完整地描述了理想材料零件的几何、拓扑和材料信息；定义了快速制造中必不可少的切片数据格式；在该数据格式的基础上，进行了理想材料零件的均匀切片算法研究，并通过实例验证了该均匀算法。     

Exact solutions for dynamic analysis of composite plates with distributed piezoelectric layers

Exact solutions are presented for analyzing dynamics of composite plates with piezoelectric layers bonded at the top and the bottom surfaces. The expressions for mechanical displacements, stresses, electric displacements and potential are derived from constitutive relations and field equations for the piezoelectric medium under applied surface traction and electric potential. The procedure is illustrated with a simply supported symmetric cross-ply (0°/90°/0°) graphite–epoxy composite plate covered with piezoelectric material polyvinylidene fluoride (PVDF). Results are in good agreement with those obtained from finite element model.     

高校《Flash》中元件与实例的教学设计

随着Flash技术的不断成熟与普及发展,Flash软件已广泛应用到社会的各个领域。很多高校在平面设计、网络技术、机电、动漫、影视等专业都增设了此课程。而元件与实例是Flash软件的重点和难点部分。本文针对高校学生的特点,本着如何让学生真正掌握这门技术,熟练运用软件工具,将成果运用到社会实践中去的目的,根据教学对象、教学内容、教学目标等,探讨讲授这门课程的科学方法和技巧。     

Java Web开发中过滤器组件应用及实例解析

Servlet过滤器是Java Web应用中的常用组件,可以拦截请求和响应,以便查看、提取或以某种方式操作客户机和服务器之间交换的数据,具有功能强大、部署简捷的特点。阐述了过滤器的工作原理,组成体系,工作过程,并通过典型实例对过滤器的具体开发和部署进行了详尽说明。