微束斑X射线源LaB_6阴极电子枪的设计

LaB6阴极电子枪是微束斑X射线源的关键组成部件之一。详细的讨论了电子枪的各组成电极 ,即LaB6阴极、Wehnelt栅极和阳极的设计。采用边界元法 (BEM )对电子枪内部电场电位和场强分布进行了有效的数值计算 ,并从阴极开始起利用四阶Runge Kutta法追踪电子的运动轨迹。给出了当阳极端口处电子束半径为设计值时各电极电压、电极结构等工作参量 ,利用该LaB6阴极电子枪可以满足微束斑X射线源需要高亮度、微细电子束发射的要求。     

Long-time Convergence of Fully Discrete Nonlinear Galerkin Method——Case of Finite-elements

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　ＴｈｅｎｏｎｌｉｎｅａｒＧａｌｅｒｋｉｎｍｅｔｈｏｄｉｓａｎｅｆｆｅｃｔｉｖｅｎｕｍｅｒｉｃａｌｍｅｔｈｏｄｆｏｒｓｏｌｖｉｎｇａｄｉｓｓｉｐａｔｉｖｅｅｖｏｌｕｔｉｏｎｅｑｕａｔｉｏｎ ,ｗｈｉｃｈｃａｎｂｅｒｅｇａｒｄｅｄａｓａｐｒｏｊｅｃｔｉｏｎｏｆｔｈａｔｅｑｕａｔｉｏｎｏｎｔｏａｎｏｎｌｉｎｅａｒａｐｐｒｏｘｉｍａｔｅｉｎｅｒｔｉａｌｍａｎｉｆｏｌｄ (ＡＩＭ )ｃｌｏｓｅｄｔｏｔｈｅａｔｔｒａｃｔｏｒ .ＴｈｅｒｅｆｏｒｅｔｈｅｎｏｎｌｉｎｅａｒＧａｌｅｒｋｉ…     

多步Runge-Kutta方法关于一类多延迟系统的GP_k-稳定性(英文)

本文涉及多步 Runge-Kutta方法关于多延迟微分方程系统的渐近稳定性 .在本文中我们证明了在适当条件下常微多步 Runge-Kutta方法的 A-稳定性等价于相应求解多延迟微分方程系统的GPk-稳定性 .     

多滞量线性微分方程系统的数值收敛性分析

1　引　　言本文将涉及多滞量线性微分方程系统y′(t)=By(t)+km=1Bmy(t-τm),t∈[t0,T],y(t)=φ(t),t∈[t0-τ,t0],(1.1)其中B=(bij),Bm=(b(m)ij)∈CN×N,0<τm≤τ(1≤m≤k),y(t)=(y1(t),y2(t),…,yN(t))T∈CN是未知函数.下文中恒设(1.1)有唯一充分光滑的解y(t),且其满足‖y(i)(t)‖≤Mi,　　t∈[t0-τ,T],(1.2)这里‖·‖为CN中某内积〈·,·〉导出的范数,即‖ξ‖=〈ξ,ξ〉(ξ∈CN).文[1]中指出:当(1.1)的系数阵满足km=1‖Bm‖<-12λmax(B+B*)(1.3)时(其中矩阵范数‖·‖定义为:‖B‖=sup‖ξ‖=1‖Bξ‖,B∈CN×N),系统(1.1…     

A computational study of the one‐dimensional parabolic equation subject to nonclassical boundary specifications

Certain problems arising in engineering are modeled by nonstandard parabolic initial‐boundary value problems in one space variable, which involve an integral term over the spatial domain of a function of the desired solution. Hence, in the past few years interest has substantially increased in the solutions of these problems. As a result numerous research papers have also been devoted to the subject. Although considerable amount of work has been done in the past, there is still a lack of a completely satisfactory computational scheme. Also, there are some cases that have not been studied numerically yet. In the current article several approaches for the numerical solution of the one‐dimensional parabolic equation subject to the specification of mass, which have been considered in the literature, are reported. Finite difference methods have been proposed for the numerical solution of the new nonclassic boundary value problem. To investigate the performance of the proposed algorithm, we consider solving a test problem. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006     

轨道预定路径控制问题的求解

轨道预定路径控制问题，其数学模型是一个非线性的半显式微分／代数方程（ＤＡＥ）系统。本文运用一类稳式Ｒｕｎｇｅ－Ｋｕｔｔａ方法求解指标２的ＤＡＴ系统，并举例说明这类方法的有效性。