超线性与二次收敛序列线性方程组算法

本文,在无严格互补条件下,对非线性不等式约束最优化问题提出了一个新的序列线性方程组(简称SSLE)算法．算法有两个重要特征:首先,每次迭代,只须求解一个线性方程组或一个广义梯度投影阵,且线性方程组可以无解．其次,初始点可以任意选取．在无严格互补条件下,算法仍有全局收敛性、强收敛性、超线性收敛性及二次收敛性．文章的最后,还对算法进行了初步的数值实验．     

解初值问题Y＇＇=g（x，y）的含参数块方法

引言 对于二阶常微分方程的初值问题 y＇＇=g（x,y）,y（x0）=y0,x0≤x≤T 的数值解法的研究引起人们的广泛兴趣．对于直接积分（1），自从1976年J．D．Lambert和I.A．waston[1]提出二阶P-稳定方法和1978年G．Dahlquist[2]证明P-稳定常系数线性多步方法的最高相容阶不超过的重要结论以来，截止目前，     

Neural Signal Tuned by Random Long-range Connections in Coupled FitzHugh-Nagumo Neurons Systems

We investigate the effect of random long-range connections on signal propagation in an array of coupled FitzHugh- Nagumo （FHN） neurons. The neural network can be obtained by randomly adding a small fraction of shortcuts in an originally locally coupled one-dimensional chain. It is shown that when the first neuron is subjected to external stimuli, it fires and excites its connected neighbours, such that the neural signal may propagate along the chain favoured by the shortcuts. Moreover, there exists an optimal number of shortcuts which can lead to the most synchronous behaviour. In addition, how the region of the fraction of shortcuts varies with the coupling strength is also discussed. These results suggest that topological disorder in the neural network may play a vital role in helping information processing in living systems.     

Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard

A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave dock, like the 5071 Cs clock （from Hp to Agilent, now Symmetricom company）, both in accuracy and stability.     

Fast Optical Switching Using Oriented Cyanine Dye-Doped Nematic Liquid Crystal

A cyanine dye, 2-[7-（1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene）-1,3,5-heptatrienyl]-1,3,3-trimethyl-3H-indolium iodide （NK-125）, is doped in 4-cyano-4＇-pentylbiphenyl （5 CB）, and the mixture is sandwiched between two pieces of rubbed glass plates. The third-order nonlinear optical properties of the oriented NK-125-SCB layers are measured by the resonant femtosecond degenerate four-wave mixing （DFWM） technique at 760 nm. The third-order nonlinear optical susceptibility of one of the present samples is 5.5×10^-8 esu. The slow DFWM response of the NK-125-SCB layers due to a population grating is accelerated by the increasing laser power because of amplified spontaneous emission （ASE）. On the other hand, we do not observe a similar phenomenon for NK-125- polyethylene glycol （PEG-400）. Oriented NK-125 molecules in nematic liquid crystals must have very high ASE efficiency. Hence the population grating in a DFWM signal disappears within about 4 ps. It is expected that NK-125-SCB can be used as a material for very fast all-optical switching.     

具常数特征拟线性双曲型方程组Cauchy问题

考虑具常数特征拟线性双曲型方程,提出一个新的可化约方程组的方法,证明了具常特征方程组Cauchy问题经典解的整体存在性定理.同时构造一些例子说明一些有趣的现象.     

具有反馈控制的非自治Logistic模型的正周期解

A nonautonomous delayed logistic model with linear feedback regulation is pro- posed in this paper.Sufficient conditions are derived for the existence,uniqueness and global asymptotic stability of positive periodic solution of the model.     

交换环上的典型群在一般线性群中的扩群

对任一有1的交换环R, 给出了R上的酉群U_2nR(n≥ 5,含辛群, 正交群和标准酉群) 在R上一般线性群GL_2n R 中扩群的完整刻画.     

基于悬臂梁的光纤光栅线性调谐器研究

分析了基于悬臂梁的光纤光栅线性调谐的基本原理及调谐公式,指出了调谐范围、调谐灵敏度和反射波谱展宽与悬臂梁结构的关系,并提出了优化方案.实验中选用适当尺寸的悬臂梁,对粘贴其上的光纤光栅的反射波长实现了线性调谐,并可对调谐范围、灵敏度等指标进行灵活控制.     

半导体激光器温控电路分析与测试

阐述了半导体热电致冷器(TEC)的基本工作原理,分析了TEC线性驱动和PWM驱动的原理以及采用PWM驱动的优点,介绍了PID温度补偿控制的原理,并设计了实验.采用相同的测试条件,对MAX1978、ADN8830和线性功率管进行了性能测试,实验数据表明温度控制电路采用PWM驱动功耗更小,全温(-40～60℃)控制效果更好.