Dimension splitting algorithm for a three-dimensional elliptic equation

This paper presents a finite-element dimension splitting algorithm (DSA) for a three-dimensional (3D) elliptic equation in a cubic domain. The main idea of DSA is that a 3D elliptic equation can be transformed into a series of two-dimensional (2D) elliptic equations in the X–Y plane along the Z-direction. The convergence speed of the DSA for a 3D elliptic equation depends mainly on the mesh scale of the Z-direction. P ₂ finite-element discretization in the Z-direction for DSA is adopted to accelerate the convergence speed of DSA. The error estimates are given for DSA applying P ₁ or P ₂ finite-element discretization in the Z-direction. Finally, some numerical examples are presented. We apply the parallel solving technology to our numerical examples and obtain good parallel efficiency. These numerical experiments test and verify theoretical results.     

DCT- and DST-based splitting methods for Toeplitz systems

New splitting iterative methods for Toeplitz systems are proposed by means of recently developed matrix splittings based on discrete sine and cosine transforms due to Kailath and Olshevsky [Displacement structure approach to discrete-trigonometric transform-based preconditioners of G. Strang type and of T. Chan type, SIAM J. Matrix Anal. Appl. 26 (2005), pp. 706–734]. Theoretical analysis shows that new splitting iterative methods converge to the unique solution of a symmetric Toeplitz linear system. Moreover, an upper bound of the contraction factor of our new splitting iterations is derived. Numerical examples are reported to illustrate the effectiveness of new splitting iterative methods.     

Delay bound analysis and splitting strategies of concurrent transmission in heterogeneous networks

We focus our attention on how to get optimal performance of concurrent transmission in heterogeneous networks. An equivalent queuing model is used to analyze the end-to-end delay performance of perfect splitting strategy with the theoretical delay bound found. Furthermore, two splitting algorithms, Minimum Queuing Delay based splitting strategy (MQD) and Unified Queuing Management Based Splitting Strategy (UQM), are presented based on the joint resources scheduled in different RATs (Radio Access Technology). In the two-RAT scenario, the two-dimensional discrete-state continuous-time Markov process is used to analyze our schemes with close-formed solutions found. Simulation results demonstrate that our proposed flow splitting strategies utilize the system resources efficiently and outperform current strategies, getting close to the theoretical delay bound especially in the heavy load region.     

一种变步长星座匹配多模算法

常数模算法(CMA)在QAM信号上的星座图匹配,存在剩余误差大、无法纠正相位偏差等问题。为此,在研究盲均衡算法的基础上,根据高阶QAM 信号的星座图特点,构造新型的均衡估值函数,并采用误差能量作为步长变化的依据,提出一种变步长星座匹配多模算法。仿真实验结果表明,该算法具有较好的收敛效果,且能改善位偏转,保持CMA算法的鲁棒性。     

基于模糊聚类的高维划分策略研究

数据集的划分策略是影响高维数据库索引性能的一个关键因素。金字塔技术是一种较好的高维索引方法，但它只对均匀分布的数据集具有良好的性能。为此，提出了一种改进的基于模糊聚类的金字塔技术，并将其用于高维划分策略，先对数据集进行模糊聚类处理，然后针对每个聚类进行金字塔划分，从而较好地实现了对非均匀分布数据的高维划分。     

新型光解水制氢用半导体光催化材料的研究进展

综述了钛酸盐、钽酸盐和铌酸盐为主的层状钙钛矿型光催化材料,简述了层状钙钛矿型光催化剂光解水的机理,比较了各种层状钙钛矿型结构材料的催化活性,分析了影响活性的原因,并对层状钙钛矿型结构光催化材料的研究和应用提出了一些自己的观点.     

功率合成与分配网络的混合模式 S参数分析方法

文中应用混合模式S参数分析了功率合成／分配网络，给出了网络的单端S参数与混合模式S参数之间相互转化的关系式。最后在测量单端S参数的基础上给出了混合模式S参数的曲线，其与理论分析的结果具有较好的一致性。     

R2Fe17Mx化合物的磁性研究

用自旋极化的ＭＳ－Ｘα方法计算了Ｎｄ２Ｆｅ１７Ｎｘ（ｘ＝０，３）化合物中含哑铃Ｆｅ原子对的Ｆｅ８及含Ｎｄ原子的ＮｄＦｅ６原子簇的电子结构和磁矩。计算结果显示，Ｎｄ２Ｆｅ１７化合物在Ｆｅ（ｃ）和Ｆｅ（ｆ）间的分子轨道中，有三个奇宇称轨道呈现负交换耦合。通过比较α－Ｆｅ的ＭＳ－Ｘａ计算结果能够箐好地说明Ｒ２Ｆｅ１７化合物居里温度较低的原因。在化合物Ｎｄ２Ｆｅ１７Ｎ３中Ｆｅ（ｃ）－Ｆｅ（ｆ）间分子轨道只     

应用聚类有效性函数指导数据分类算法的研究

研究了应用聚类有效性函数指导数据分类的算法,指出文[6]中算法的不足并对其进行了修改。实验结果表明,修改后的算法是可行的。