国标中断面图的概念、画法及标注的存在问题浅谈

结合机械制图教学实践，分析了GB／T17452-1998《技术制图 图样画法 剖视图和断面图》中的概念、画法、标注中存在的问题，提出了相应的修改建议。意在探讨技术制图标准中概念、画法的科学性、严密性。使之不断完善。     

利用图解图框画法,描述IT课堂教学

该文探讨了现代计算机软件教学中引进板书“图解图框”画法进行IT软件课堂教学描述，定义了与IT软件窗口对应的板书“图解图框”的基本符号．总结了板书“图解图框”的基本画法，阐述了图解图框画法在黑板教学及编辑现代IT软件教材中的优势及如何掌握和运用板书“图解图框”方法。     

Series-parallel图的Δ-SP算法的实现

讨论了series-parallel图和它的二叉分解树，对S－P图的Δ－SP画法进行了详细的描述，给出了该算法的实现过程，并且对S－P图的分解树建树算法进行了改进。最后，通过一个具体实例尝示了该画法的结果。     

正弦曲线的画法演示

正弦曲线的画法演示，可以在高中数学第一册第四章第八节《正弦函数，余弦函数的图像和性质》一节教学使用，课件可以重复地模拟正弦曲线的几何画法．使学生能够动态直观地感受正弦曲线的形成过程。     

国标中断面图的概念、画法及标注的存在问题浅谈

结合机械制图教学实践,分析了GB/T17452-1998《技术制图图样画法剖视图和断面图》中的概念、画法、标注中存在的问题,提出了相应的修改建议。意在探讨技术制图标准中概念、画法的科学性、严密性,使之不断完善。     

AutoCAD中连接圆弧的画法研究

通过对AutoCAD中连接圆孤的做图原理加以分析,总结归纳出九类连接圆弧的画法,几乎涵盖了所有连接圆弧的画法,大大提高了绘图效率.     

影像反求的基本方法与透视图画法之间的联系

文章从透视图作图的理论范畴与本质方面入手,比较发现照片影像与透视图的成像原理的一致性,并在透视图反求中可以将照片影像作为透视图看待。重点剖析了透视图中建筑师法和量点法两种基本画法,并通过这两种画法来分析影像反求与透视图画法之间的联系。     

AUTOCAD应用技巧

介绍几种AUTOCAD软件工程设计应用技巧,如轴类零件的画法、三角形内切圆画法、指定锥度的直线画法、捕捉切点的应用技巧、利用圆角命令连接未封闭线段、箭头画法等,有助于提高绘图效率和准确性。     

对国标中圆锥滚子轴承特征画法的探讨

国家标准中规定了圆锥滚子轴承的特征画法.通过将该画法中的矩形宽度与轴承实际宽度进行对比,发现了两个问题:对部分国锥滚子轴承而言,遵循该画法所得到的图与标准本身所表述矛盾;另外在装配图中不能正确地表达机器的装配关系.为此提出了解决问题的建议供参考.     

Series-parallel图的△-SP算法的实现

讨论了图和它的二叉分解树,对图的△画法进行了详细的描述,给出了该算法的实现过程,并且对图的分解series-parallelS-P-SPS-P树建树算法进行了改进。最后,通过一个具体实例演示了该画法的结果。     

基于n叉树的动态安全群密钥协商协议

将三叉树拓展为n叉树引入到群密钥中,提出了动态安全的基于n叉树的可认证群密钥协商协议。在三叉树的基础上进一步减少了轮数,计算复杂度由O(log3 m)降低为O(logn m),但是单轮内成员间通信量增加。群内成员先进行树结构的划分,每n个节点作为相应上一级节点的孩子节点,n个节点分别选定代表,n个代表通过调用协议BCP协商密钥得到本轮即相应父亲节点的子密钥,重复进行上述过程最终可以得到群组密钥。同时,协议考虑了有成员加入或离开的动态情形并给出了很好的解决方案,一方面保证了动态情形发生时,在前一时刻计算出结     

On the parity complexity measures of Boolean functions

The parity decision tree model extends the decision tree model by allowing the computation of a parity function in one step. We prove that the deterministic parity decision tree complexity of any Boolean function is polynomially related to the non-deterministic complexity of the function or its complement. We also show that they are polynomially related to an analogue of the block sensitivity. We further study parity decision trees in their relations with an intermediate variant of the decision trees, as well as with communication complexity.     

基于特征路径的XML文档变化检测算法

由于在线信息变化频繁,XML文档变化快速检测成为Internet查询系统、搜索引擎以及连续查询系统的关键技术。目前国际上的研究主要集中于有序模式的XML文档比较,针对有序模式最好的算法复杂度为O(nkgn),其中n为文档的长度,而针对无序模式为多项式时间复杂度,为提高处理效率,提出一种基于特征路径的变化检测算法,将传统标号树匹配问题转换为基于特征路径的无重复路径标号树的匹配问题,同时适于有序和无序两种模式,复杂度为O(n),其中n为文档结点的个数．实验证明KF-Diff 能够非常高效地比较XML文档。     

Linear Bidirectional On-Line Construction of Affix Trees

Affix trees are a generalization of suffix trees that are based on the inherent duality of suffix trees induced by the suffix links. An algorithm is presented that constructs affix trees on-line by expanding the underlying string in both directions and that is the first known algorithm to do this with linear time complexity.     

A mass assignment based ID3 algorithm for decision tree induction

A mass assignment based ID3 algorithm for learning probabilistic fuzzy decision trees is introduced. Fuzzy partitions are used to discretize continuous feature universes and to reduce complexity when universes are discrete but with large cardinalities. Furthermore, the fuzzy partitioning of classification universes facilitates the use of these decision trees in function approximation problems. Generally the incorporation of fuzzy sets into this paradigm overcomes many of the problems associated with the application of decision trees to real-world problems. The probabilities required for the trees are calculated according to mass assignment theory applied to fuzzy labels. The latter concept is introduced to overcome computational complexity problems associated with higher dimensional mass assignment evaluations on databases. ©1997 John Wiley & Sons, Inc.     

Linear Bidirectional On-Line Construction of Affix Trees

Affix trees are a generalization of suffix trees that are based on the inherent duality of suffix trees induced by the suffix links. An algorithm is presented that constructs affix trees on-line by expanding the underlying string in both directions and that is the first known algorithm to do this with linear time complexity.     

The complexity of tree automata and XPath on grammar-compressed trees

The complexity of various membership problems for tree automata on compressed trees is analyzed. Two compressed representations are considered: dags, which allow to share identical subtrees in a tree, and straight-line context-free tree grammars, which moreover allow to share identical intermediate parts in a tree. Several completeness results for the classes NL, P, and PSPACE are obtained. Finally, the complexity of the evaluation problem for (structural) XPath queries on trees that are compressed via straight-line context-free tree grammars is investigated.     

Omnivariate decision trees.

Univariate decision trees at each decision node consider the value of only one feature leading to axis-aligned splits. In a linear multivariate decision tree, each decision node divides the input space into two with a hyperplane. In a nonlinear multivariate tree, a multilayer perceptron at each node divides the input space arbitrarily, at the expense of increased complexity and higher risk of overfitting. We propose omnivariate trees where the decision node may be univariate, linear, or nonlinear depending on the outcome of comparative statistical tests on accuracy thus matching automatically the complexity of the node with the subproblem defined by the data reaching that node. Such an architecture frees the designer from choosing the appropriate node type, doing model selection automatically at each node. Our simulation results indicate that such a decision tree induction method generalizes better than trees with the same types of nodes everywhere and induces small trees.     

一种改进的点在多边形内外判断算法

为解决多边形内外算法中BSP树退化为链表的问题,提出一种改进的点在多边形内外的判断算法。在构建水平扫描线的BSP树之前,对水平扫描线按照Y值进行排序,将排好序的水平扫描线按照二分法的顺序插入到BSP树中,其查找时间复杂度为O(lbn)。实验结果表明,该算法在不增加BSP构建时间复杂度的前提下,能够保证BSP树的查找效果总是最优的,且简单易行,具有较好的通用性。     

增量决策树算法研究

文中主要解决传统的ID3算法不能处理增量数据集构造决策树的问题。在传统ID3决策树算法和原有增量算法的基础上,利用信息论中熵变原理的特点,对与增量决策树算法相关的三个定理进行相应的改进,在理论上证明了改进的增量决策树算法的有效性和可靠性。同时对增量决策树算法和ID3算法的复杂度进行了对比分析,得出增量决策树算法的实例费用和信息熵费用都高于ID3算法的结论。最后通过一个实验证明,改进的增量决策树算法能够构造出与ID3算法形态基本相同的决策树。