三维差分格式的网络图论方法

本文给出了椭圆型边值问题的通用三维差分格式,并以网络图论为基础,着重讨论并介绍了该格式的实施步骤及其在各种控制容积单元中的应用.     

数字下变频器的原理与实现方法

阐述了数字下变频器(Digital Down Conversion,DDC)的原理.DDC主要由数字控制振荡器、混频器、低通滤波器等部分组成,DDC是将中频信号与数字控制振荡器产生的载波信号进行混频,再经过低通滤波器得到基带信号,实现了下变频功能.分别介绍了用查表法、坐标旋转数值计算机算法和MVR CORDIC)算法3种方法实现DDC的过程.基于这3种方法设计的DDC应用广泛,同时也适合用于FPGA器件实现.     

A fast construction method for spatial index GBD-tree

This paper proposes a fast initial construction method of the GBD-tree. The GDB tree has proper characteristics for management of large amount of 2 or 3 dimensional data. However, the GBD-tree needs long initial construction time by originally proposed one-by-one insertion method. A fast insertion method has been proposed, but it needs large size of buffer capable to hold index information of all entries. The paper proposes another fast initial construction method. The method requires only limited size of work space (buffer). The experimental results show the initial construction time reduces into a third or a quarter of the one-by-one insertion method. The memory efficiency and retrieval efficiency are also improved than the one-by-one insertion method.     

1-树与外平面图的无圈边着色

设f是图G的一个正常边着色，若在f下G中没有2-色圈，则称f是图G的一个无圈边着色，其所用最小色数为G的无圈边色数。N．Alon猜想对所有简单图，无圈边色数不超过其最大度加2。本文证明了该猜想对1-树与外平面图成立，且它们的色数均不超过最大度加1。     

求解VLSI不可二划分布图规划问题的混合遗传算法

超大规模集成电路(VLSI)布图规划是VLSI物理设计的关键环节之一,对集成电路的芯片面积、线长等性能指标有重大影响.基于B*-tree的结构表示,结合遗传算法的思想,提出一种用于解决VLSI不可二划分布图规划问题的混合遗传算法,并用MCNC标准测试例子对所设计的算法进行测试,证明该算法的有效性.     

An efficient spatio-temporal data structure for multi version management of engineering drawings

In the engineering database system, multiple versions of a design including engineering drawings should be managed efficiently. The paper proposes an efficient spatial data structure, that is an expansion of the R-tree and HR-tree, for version management of engineering drawings. A novel mechanism to manage the difference between drawings is introduced to the HR-tree to eliminate redundant duplications and to reduce the amount of storage required for the data structure. Data management mechanism and structural properties of our data structure called the MVR -tree are described.     

3-树的二次整子图的色性

本文证明了ｎ（≥５）阶图Ｇ是３－树的二次整子图的充要条件为Ｐ（Ｇ；λ）＝λ（λ－１）（λ－２）＾３（λ－３）＾ｎ－５。     

(m,n)-树的几个判定条件

通过构造(m,n)-树的(m,n)-图,给出了判断(m,n)-树的几个充分必要条件,从而进一步揭示了(m,n)-树的结构特征。     

An efficient spatio-temporal data structure for multi version management of engineering drawings

In the engineering database system, multiple versions of a design including engineering drawings should be managed efficiently. The paper proposes an efficient spatial data structure, that is an expansion of the R-tree and HR-tree, for version management of engineering drawings. A novel mechanism to manage the difference between drawings is introduced to the HR-tree to eliminate redundant duplications and to reduce the amount of storage required for the data structure. Data management mechanism and structural properties of our data structure called the MVR -tree are described.     

(m,n)-树的一个充分必要条件

通过在(m,n)-树中引入Graham约化过程,给出了(m,n)-树的一个充分必要条件。