Friction compensation design based on state observer and adaptive law for high-accuracy positioning system

Friction is one of the main factors that affect the positioning accuracy of motion system. Friction compensation based on friction model is usually adopted to eliminate the nonlinear effect of friction. This paper presents a proportional-plus-derivative (PD) feedback controller with a friction compensator based on LuGre friction model. We also design a state observer to observe the unknown state of LuGre friction model, and adopt a parameter adaptive law and off-line approximation to estimate the parameters of LuGre friction model. Comparative experiments are carried out among our proposed controller, PD controller with friction compensation based on classical friction model, and PD controller without friction compensation. Experimental results demonstrate that our proposed controller can achieve better performance, especially higher positioning accuracy.     

重载运输中扼流变压器容量配置预算的理论基础

在电气化铁道中，钢轨既是机车牵引电流回流的通道，又是自动闭塞系统传输信息的通道，两者之间存在着电磁兼容性的问题。本文首先介绍了一种现场模拟产生大牵引电流的方法，然后在实测数据的基础上，分析了钢轨回流随牵引电流的变化关系．根据轨流在一定范围内随牵引电流呈线性变化这一关系，可以在己有测试数据的基础上预测出重载运输牵引电流下，钢轨回流的大小，确定沿线扼流变压器容量的配置。这为扼流变压器容量的预先配置计算奠定了电流特性方面的理论基础。     

具有典则联系函数的广义线性模型的诊断

本文首先给出了广义线性模型中的Ｋ－Ｌ距离和信息距离，讨论了它们的近似式及其相互关系，据此可用来检测异常点。并结合局部影响分析的思想得到了简易的诊断图，研究了回归变量的重要性以及各个观察数据对它的影响。最后给出了应用实例。     

解Navier－Stokes方程的线性协调元方法的收敛性定理

将线性协调元方法用于解Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，对速度近似可以得到按［Ｈ１（Ω）］ｎ模的最优阶敛速估计．     

线摩擦驱动带式输送机动力分析及动态设计

简述线摩擦驱动原理，分析并实测弹性波在输送带中的传播速度；在分析线摩擦驱动带式输送机动力过程的基础上，提出带式输送机的动态设计方法及其应用程序。     

Linear restrictions and two step least squares with applications

In this paper we consider the full rank regression model with arbitrary covariance matrix: Y = Xß + ε. It is shown that the effect of restricting the information Y to T = A′Y may be analyzed through an associatedi regression problem which is amenable to solution by two step least squares. The results are applied to the important case of missing observations, where some classical results are rederived.     

The asymptotic validity of invariant procedures for the repeated measures model and multivariate linear model

Fairly general sufficient conditions are given to guarantee that invariant tests about means in the multivariate linear model and the repeated measures model have the correct asymptotic size when the normal assumption under which the tests are derived is relaxed. These conditions are the same as Huber's condition which guarantees asymptotic validity of the size of the F-test for the univariate linear model.     

锥形弹簧中驻波的理论探讨

本文对模拟一维非均匀介质的锥形弹簧中纵波的传播规律作了理论探讨。所得结果与实验符合得较好。     

线性矩阵不等式F_0＋sum from j＝1 to k of x_j F_

应用矩阵求迹运算“ｔｒ（·）”得到了线性矩阵不等式Ｆ_０＋sum from j=1 to k of ｘ_ｊ Ｆ_ｊ＞０解的充分条件，这些充分条件皆为应用中容易检验的代数不等式．并据此给出了相应的代数解