微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统...微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统鲁棒性以及广义时间常量来配置系统特征多项式,从而设计控制器。针对CRA设计控制器阶次的不明确,提出依据CRA设计满足一定性能指标的定阶次的类PID控制器。仿真分析证实了提出的控制方法简单可行。展开更多
We study the optimal order of approximation for |x|α (0 < α < 1) by Lagrange interpolation polynomials based on Chebyshev nodes of the first kind. It is proved that the Jackson order of approximation is attained.
The purpose for this research was to investigate the Riemann zeta function at odd integer values, because there was no simple representation for these results. The research resulted in the closed form expression <i...The purpose for this research was to investigate the Riemann zeta function at odd integer values, because there was no simple representation for these results. The research resulted in the closed form expression <img src="Edit_909dc64a-717a-4477-a9f8-a3b94ab4008e.bmp" alt="" /> for representing the zeta function at the odd integer values 2<em>n</em>+1 for <em>n</em> a positive integer. The above representation shows the zeta function at odd positive integers can be represented in terms of the Euler numbers <em>E</em><sub>2<em>n</em></sub> and the polygamma functions <em>ψ</em><sup>(2<em>n</em>)</sup>(3/4). This is a new result for this study area. For completeness, this paper presents a review of selected properties of the Riemann zeta function together with how these properties are derived. This paper will summarize how to evaluate zeta (n) for all integers n different from 1. Also as a result of this research, one can obtain a closed form expression for the Dirichlet beta series evaluated at positive even integers. The results presented enable one to construct closed form expressions for the Dirichlet eta, lambda and beta series evaluated at odd and even integers. Closed form expressions for Apéry’s constant zeta (3) and Catalan’s constant beta (2) are also presented.展开更多
Two interesting sequences arose in the study of the series expansions of the complete elliptic integrals,which are called the Catalan-Larcombe-French sequence{Pn}n≥0 and the Fennessey-Larcombe-French sequence{Vn}n≥0...Two interesting sequences arose in the study of the series expansions of the complete elliptic integrals,which are called the Catalan-Larcombe-French sequence{Pn}n≥0 and the Fennessey-Larcombe-French sequence{Vn}n≥0 respectively.In this paper,we first establish some criteria for determining log-behavior of a sequence based on its three-term recurrence.Then we prove the log-convexity of{Vn^2-V(n-1)V(n+1)}n≥2 and{n!Vn}n≥1,the ratio log-concavity of{Pn}n≥0 and the sequence{An}n≥0 of Apéry numbers,and the ratio log-convexity of{Vn}n≥1.展开更多
文摘微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统鲁棒性以及广义时间常量来配置系统特征多项式,从而设计控制器。针对CRA设计控制器阶次的不明确,提出依据CRA设计满足一定性能指标的定阶次的类PID控制器。仿真分析证实了提出的控制方法简单可行。
文摘We study the optimal order of approximation for |x|α (0 < α < 1) by Lagrange interpolation polynomials based on Chebyshev nodes of the first kind. It is proved that the Jackson order of approximation is attained.
文摘The purpose for this research was to investigate the Riemann zeta function at odd integer values, because there was no simple representation for these results. The research resulted in the closed form expression <img src="Edit_909dc64a-717a-4477-a9f8-a3b94ab4008e.bmp" alt="" /> for representing the zeta function at the odd integer values 2<em>n</em>+1 for <em>n</em> a positive integer. The above representation shows the zeta function at odd positive integers can be represented in terms of the Euler numbers <em>E</em><sub>2<em>n</em></sub> and the polygamma functions <em>ψ</em><sup>(2<em>n</em>)</sup>(3/4). This is a new result for this study area. For completeness, this paper presents a review of selected properties of the Riemann zeta function together with how these properties are derived. This paper will summarize how to evaluate zeta (n) for all integers n different from 1. Also as a result of this research, one can obtain a closed form expression for the Dirichlet beta series evaluated at positive even integers. The results presented enable one to construct closed form expressions for the Dirichlet eta, lambda and beta series evaluated at odd and even integers. Closed form expressions for Apéry’s constant zeta (3) and Catalan’s constant beta (2) are also presented.
基金partially supported by the National Science Foundation of Xinjiang Uygur Autonomous Region(No. 2017D01C084)the National Science Foundation of China (Nos. 11771330 and 11701491)
文摘Two interesting sequences arose in the study of the series expansions of the complete elliptic integrals,which are called the Catalan-Larcombe-French sequence{Pn}n≥0 and the Fennessey-Larcombe-French sequence{Vn}n≥0 respectively.In this paper,we first establish some criteria for determining log-behavior of a sequence based on its three-term recurrence.Then we prove the log-convexity of{Vn^2-V(n-1)V(n+1)}n≥2 and{n!Vn}n≥1,the ratio log-concavity of{Pn}n≥0 and the sequence{An}n≥0 of Apéry numbers,and the ratio log-convexity of{Vn}n≥1.
