自相位调制和交叉相位调制共同作用下抽运探测波结构中的信号扰动研究

针对强度调制直接检测波分复用系统研究了抽运探测波结构中自相位调制和交叉相位调制共同作用下的光信号传输,给出了确定任意抽运信号下的探测波时域波形及强度调制率的理论解析方法,分析了信道间隔、传输速率对于交叉相位调制的影响,发现抽运波自相位调制的作用主要体现在使探测波时域强度调制率有所增大,解析结果和数值仿真能较好地吻合。     

Multiaccess in all-optical networks with wavelength and code concurrency

A major obstacle in realizing fast packet switching in all-optical networks is the large tuning delays of tunable optical devices. This article proposes a multiaccess scheme for all-optical local area networks that employs both wavelength and code concurrency. In this scheme, several users share a wavelength channel through code multiplexing. The delay performance of hybrid wavelength/code division multiaccess is obtained under a simple, suboptimal access protocol based on cyclic search. Due to the reduction in the number of wavelength channels without an associated reduction in transmission concurrency, hybrid multiaccess is robust against tuning delays. At a given network throughput, the hybrid scheme achieves considerably lower delays than that of Wavelength Division Multiple Access even with a small amount of code concurrency. Conversely, the hybrid network can support a higher load when there is a maximum allowable value for the average packet delay.     

Applications of a sequence of points in teaching linear algebra,numerical methods and discrete mathematics

Based on a sequence of points and a particular linear transformation generalized from this sequence, two recent papers (E. Mauch and Y. Shi, Using a sequence of number pairs as an example in teaching mathematics. Math. Comput. Educ., 39 (2005), pp. 198–205; Y. Shi, Case study projects for college mathematics courses based on a particular function of two variables. Int. J. Math. Educ. Sci. Techn., 38 (2007), pp. 555–566) have presented some interesting examples which can be used in teaching high school and college mathematics classes. In this article, we further discuss a few interesting ways to apply this sequence of points in teaching college mathematics courses such as linear algebra, numerical methods in computing, and discrete mathematics. In addition to using them in individual courses, these studies may also be combined together to offer seminars or workshops to college mathematics students. Studies like these are likely to promote student interests and get students more involved in the learning process, and therefore make the learning process more effective.     

TaskSelSim: a model of the self-organization of the division of labour in honeybees

We here describe a novel multi-agent model of the decentralized task selection process in honeybee colonies. The model is based on individual behavioural programs represented as hierarchical finite state automatons. We successfully simulated empirical experiments (with real honeybees) using the model. We shed more light on task specialization and polyethism in honeybees by modelling the heterogeneous environment that emerges over time inside the colony and by considering the changing differences in stimuli strength in each small area of the hive. Our simulation experiments presented here investigate the model's reaction to changing values in crucial model parameters and investigate the stability of the predicted colony behaviours.     

Computation of the random arrival rule for bankruptcy problems

Bankruptcy problems are a fundamental class of fair division problems in microeconomics. Among the various solution concepts proposed for the problem, the random arrival rule is one of the most prominent. In this paper, we conduct a computational analysis of the rule. It is shown that the allocation returned by the rule is #P-complete to compute. The general complexity result is complemented by a pseudo-polynomial-time dynamic programming algorithm for the random arrival rule.     

Lyot filter based multiwavelength fiber ring laser actively mode-locked at 10 GHz using an electroabsorption modulator

A multiwavelength fiber ring laser comprising of a Lyot filter and hybrid gain medium is presented. A wavelength channel spacing of 100 GHz is achieved by appropriate tuning of the Lyot filter length. Four wavelength channels are simultaneously mode-locked at 10 GHz using an electroabsorption modulator. We highlight how the intra-cavity modulator can affect the stability of the mode-locked laser spectrum when used in conjunction with a Lyot filter. We show that, due its reduced polarization sensitivity, an electroabsorption modulator significantly improves the stability of the mode-locked laser spectrum when compared to using a Mach-Zehnder modulator.     

基于风洞试验的不同坡度多跨锯齿屋面风压特性研究

多跨锯齿屋面因其具有跨度大、结构轻盈的特点成为典型的风灾易损结构.目前国内规范对锯齿屋盖的风荷载规定较为粗略,简单给定了统一的风压系数参考值,在实际工程应用中具有一定的局限性.本文以某4跨锯齿房屋为研究对象,通过风洞试验测试了15°、21°、26°、30°和40°等5种不同屋面坡度对锯齿屋盖风压特性的影响.试验结果表明...     

齿轮有限元强度计算的单元自动生成

本文提出了一种专用于齿轮有限元强度计算的单元自动生成办法,只需输入法截面内一半数据,便可自动生成空间二十节点等参元的全部数据。本文严格地以实际齿面方程所描述的齿廓曲面体为计算对象,并按轮齿法截面划分单元,也适合于其他柱面体和螺旋面体的有限元计算。     

Experimental analysis of crack tip fields in rubber materials under large deformation

A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation.The model is inspired by the distribution of the measured in-plane and out-of-plane deformation.The inplane displacement of crack-tip fields under both Mode I and mixed-mode(Mode I-II) fracture conditions is measured by using the digital Moire’ method.The deformation characteristics and experimental sector division mode are investigated by comparing the measured displacement fields under different fracture modes.The out-of-plane displacement field near the crack tip is measured using the three-dimensional digital speckle correlation method.