Mitigation of EDFA transient effects in variable duty cycle pulsed signals

We report the transient effects in Erbium Doped Fiber Amplifier (EDFA) systems for pulsed signals with different duty-cycles. The work includes the analysis using three different duty-cycles, 10%, 20% and 50%. A curve fitting technique is also proposed to predict the transients of any lesser duty-cycled pulse, once the transients of a larger duty-cycled pulse is known. Mathematical evaluation confirms the double exponential shape of transient distorted signal. Further, EDFA transient effect is experimentally verified on a Wavelength Division Multiplexed (WDM) link by multiplexing high and low bitrate modulated optical signals. We conclude the paper by proposing a transient suppression technique for variable duty-cycle signals and analyzing its effectiveness with different wavelength spacing.     

舰船空调系统不同保障模式的效费分析

分析了舰船全寿命期和使用期的结构,在此基础上,借助于WSEIAC模型,分别对舰船空调系统在两种保障方式的全寿命使用期效能和费用的各个指标进行了建模,提出了指标计算的思路与计算方法.结合海军舰船特点,在对WSEIAC效能模型进行修改和完善的基础上,给出了计算示例,结果显示了海军舰船空调系统采用岸基保障方式的合理性和优越性.     

一类具Holling-Ⅲ类功能性反应的食物有限捕食-被捕食模型的极限环

研究一类具Holling-Ⅲ类功能性反应的食物有限捕食-被捕食模型的动力学性态。应用微分方程定性理论，证明当正平衡点不稳定时该模型存在唯一稳定的极限环。     

Level workforce planning for multistage transfer lines

In this article, we define two different workforce leveling objectives for serial transfer lines. Each job is to be processed on each transfer station for c time periods (e.g., hours). We assume that the number of workers needed to complete each operation of a job in precisely c periods is given. Jobs transfer forward synchronously after every production cycle (i.e., c periods). We study two leveling objectives: maximin workforce size () and min range (R). Leveling objectives produce schedules where the cumulative number of workers needed in all stations of a transfer line does not experience dramatic changes from one production cycle to the next. For and a two‐station system, we develop a fast polynomial algorithm. The range problem is known to be NP‐complete. For the two‐station system, we develop a very fast optimal algorithm that uses a tight lower bound and an efficient procedure for finding complementary Hamiltonian cycles in bipartite graphs. Via a computational experiment, we demonstrate that range schedules are superior because not only do they limit the workforce fluctuations from one production cycle to the next, but they also do so with a minor increase in the total workforce size. We extend our results to the m‐station system and develop heuristic algorithms. We find that these heuristics work poorly for min range (R), which indicates that special structural properties of the m‐station problem need to be identified before we can develop efficient algorithms. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 577–590, 2016     

对一个重要极限证明中使用循环论证问题的质疑

有的著作认为在极限公式limx→0sinxx=1的证明中,要用到圆(扇形)的面积公式S=21Lr,而对后者的证明中必须要用到重要极限limx→0sinxx=1,从而犯了循环论证的错误。魏晋刘徽的“割圆术”是对无限问题的独特认识和致用的处理方式,是为证明圆面积公式而设计出来的一种方法。刘徽之前,希腊的阿基米德用穷竭法也证明了圆的面积公式。其中,刘徽的证法强调计算的程序性和构造性,而阿基米德则倾向于演绎的严谨性。这两种证明说明limx→0sinxx=1证明所谓的循环论证是可以避免的。     

A three-stage model for the perforation of finite metallic plates by long rods at high velocities

A three-stage theoretical model is presented herein to predict the perforation of a thick metallic plate struck normally by a long rod at high velocities. The model is suggested on the basis of the assumption that the perforation of a thick metallic plate by a long rod can be divided into three stages: (1) initial penetration; (2) plug formation and (3) plug slipping and separation. Various analytical equations are derived which can be employed to predict the ballistic limit, residual velocity and residual length of the long rod. It is demonstrated that the present model predictions are in good agreement with available experimental results for the perforation of finite steel targets struck normally by steel as well as tungsten alloy long rods at high velocities. It is also demonstrated that the dynamic maximum shear stress of a plate material has strong effect on plug formation and plug thickness which, in turn, exerts considerable influence on the residual velocities and lengths of a long rod at impact velocities just above the ballistic limit.     

周期平稳通信信号时差估计

研究了一种利用信号谱相关特性对周期平稳通信信号进行时差估计的方法。研究表明,谱相关时差估计方法较之经典的广义互相关(GCC)法具有更强的抗干扰能力,在多辐射源环境下,该方法可以无模糊地估计各个辐射源的时差。     

寿命周期费用分析在保障性分析中的应用

探讨了费用分析在保障性分析中的作用和实际应用;介绍了在装备研制过程中应用保障性分析所产生的效益.     

具有等熵压缩、膨胀过程的回热式布雷顿热泵循环有限时间热力学性能

研究恒温和变温热源条件下具有等熵压缩、膨胀过程的闭式回热式布雷顿热泵循环有限时间热力学性能,导出循环供热率和供热系数与循环压比间的解析关系,由此可得最佳供热率、供热系数关系。分析中计入了工质与高、低温热源间换热器和回热器的热阻损失。     

一类可逆生化反应动力系统的定性分析

研究生化反应中一类可逆饱和反应的数学模型：应用微分方程定性理论,比较完整地解决了该系统极限环的存在性、唯一性和不存在性等问题。