铒镱共掺光波导放大器的优化

本文介绍了光波导放大器的理论,分析了由于铒离子吸收截面小和铒离子浓度过高带来的聚集效应,并认为由该聚集效应引起的协同上转换和激发态吸收会限制掺铒磷酸盐光波导放大器的增益。将镱离子作为敏化剂掺入到光波导放大器中,不仅可以降低饵离子高浓度引起的聚集,而且可以有效地解决光波导的增益问题。在考虑协同上转换效应的基础上,用龙库算法研究了饵镱共掺的光波导放大器,讨论了镱离子浓度和波导长度两个主要影响因素,并且计算出了最佳的波导长度和最佳的掺镱浓度。

Simulation and comparison of several numerical algorithms for solving ballistic differential equations

Several numerical methods of differential equations and their applications in ballistic calculation are discussed for the purpose of simplification of the dynamic differential equations of projectile trajectory.Program simulations of Euler method,Heun method,lassic fourth-order Runge Kutta（RK4）method,ABM method and Hamming method are achieved based on Matlab.In addtion,the approximate solutions,local truncation errors and calculation time of the dynamic differential equations are obtained.By analyzing the simultaion results,the advantages and disadvantages of these methods are compared,which provides a basis for choice of ballistic calculation methods.

Using contaminated tools fuels outbreaks of Banana Xanthomonas wilt： An optimal control study within plantations using Runge-Kutta fourth-order algorithms

Optimal control theory is applied to a system of ordinary differential equations modeling banana Xanthomonas wilt within plantations. The objective is to reduce the proportion of infected plants by use of controls representing two types of preventive methods： vector and contaminated tool prevention. The optimal controls are characterized in terms of the optimality system, which is solved analytically and numerically for several scenarios.