稀土永磁同步无齿轮曳引机矢量控制变频调速

交流变频调速是当前电力拖动系统的主要发展方向,本文介绍稀土永磁同步无齿轮曳引机电动机磁路结构设计的特点和矢量控制变频调速系统,分析样机性能的实测数据,说明稀土永磁同步无齿轮曳引机矢量控制变频调速具有同步调速范围宽、转矩和转速平稳、效率和功率因数高等优点,是一种高效节能的电梯拖动调速系统。     

四川省服务业与工业外溢效应的动态分析

服务业与工业间的关联关系一直受到经济学家的关注，根据四川省1994～2004年工业、服务业、交通运输仓储邮电通信业年增加值，利用运用时间序列分析法进行动态分析，可得到如下结论：工业、服务业均存在对其他产业的明显的正外溢效应；交通运输仓储邮电通信业存在对其他产业的正外溢效应，但效果不明显。     

土家族天梯神话的载体解读

土家族天梯神话折射出了一种神贵民贱的消极思想,但更重要的是弘扬了土家人探索自然、征服自然、改造自然的勇气和同大自然顽强拼搏的精神。     

非线性可分文本的SVM算法研究与改进

支持向量机(SVM)算法可用来确定非线性可分文本的待分类文本类别。支持向量机的原始问题可以归纳为一个二次规划问题。当规模较大时,标准的SVM算法训练效率较低。本文在分析SVM算法的二次规划问题及利用可行性方向法求解二次规划问题的基础上,将效率较高的可行性方向法应用于求解SVM算法中的二次规划问题,给出了非线性可分文本的SVM算法的改进算法,改进后的SVM算法在时间复杂度上有着明显的提高,从而有效提高了SVM算法的训练效率。     

辅助向量在中学数学解题中的应用

向量是高中新课程增加内容，它具有“双重身份”，可以象数一样满足“运算性质”进行代数形式的运算，又可以利用它的几何意义进行几何形式的变换．本文从三个方面论述了辅助向量在中学数学解题中的应用．     

旋转矢量在工程力学教学中的应用

利用学生已熟练掌握的矢量合成及矢量投影定理，提出了用旋转矢量来记忆并理解工程力学课程中非矢量的、难以掌握的、大量的公式和定理。即：利用三角函数的正交性，将公式中的各代数量定义为平面上可绕一点旋转的矢量表示，再根据矢量合成定理及矢量投影定理表达公式的内容。     

实时Ad hoc按需距离矢量路由协议

针对现存的Ad hoc网络路由协议普遍存在延时较大、不能满足实时应用的传输需求的缺陷,在Ad hoc按需距离矢量路由(AODV)协议的基础上,提出了一种具有实时意识的Ad hoc按需距离矢量路由协议实时Ad hoc按需要距离矢量路由(RAODV),并通过仿真实验在不同的网络状态下对RAODV与AODV的性能进行了对比。实验结果表明:在常规网络负载的情况下,RAODV可以获得和AODV同等水平的分组投递率,而数据分组的平均端到端延时和路由负荷则相对要低一些;在网络负载比较大的情况下,两种协议的性能都有所下降,但相对于AODV来说,RAODV的性能下降幅度要小很多,并且可以获得更高的分组投递率,更低的数据分组平均端到端延时和路由负荷。     

Estimation of cointegrated models with exogenous variables

We consider a cointegrated vector autoregressive process of integrated order 1, where the process consists of endogenous variables and exogenous variables. Johansen [Cointegration in partial systems and the efficiency of single-equation analysis. J Econometrics. 1992;52:389–402], Harbo et al. [Asymptotic inference on cointegrating rank in partial systems. J Amer Statist Assoc. 1998;16:388–399], and Pesaran et al. [Structural analysis of vector error correction models with exogenous I(1) variables. J Econometrics. 2000;97:293–343] considered inference of such processes assuming that the non-stationary exogenous variables are not cointegrated, and thus they are weakly exogenous. We consider the case where exogenous variables are cointegrated. Parameterization and estimation of the model is considered, and the asymptotic properties of the estimators are presented. The method in this paper is also applicable for the models considered in Mosconi and Giannini [Non-causality in cointegrated systems: representation estimation and testing. Oxford Bull Econ Stat. 1992;54:399–417], Pradel and Rault [Exogeneity in vector error correction models with purely exogenous long-run paths. Oxford Bull Econ Stat. 2003;65:629–653], and Hunter [Cointegrating exogeneity. Econom Lett. 1990;34:33–35]. A real data example is provided to illustrate the methods. Finite sample properties of the estimators are also examined through a Monte Carlo simulation.     

Numerical testing of evolution theories †

Fisher's method of combining independent tests is used to construct tests of means of multivariate normal populations when the covariance matrix has intraclass correlation structure. Monte Carlo studies are reported which show that the tests are more powerful than Hotelling's T ²-test in both one and two sample situations.     

Online learning for quantile regression and support vector regression

We consider for quantile regression and support vector regression a kernel-based online learning algorithm associated with a sequence of insensitive pinball loss functions. Our error analysis and derived learning rates show quantitatively that the statistical performance of the learning algorithm may vary with the quantile parameter τ$\tau$. In our analysis we overcome the technical difficulty caused by the varying insensitive parameter introduced with a motivation of sparsity.