全固态多波长飞秒脉冲激光系统

利用棱镜对引进频谱空间啁啾来补偿飞秒脉冲激光二次谐波产生中的相位失配,提高了倍频效率建立了一套全固态、多波长(1065nm, 532nm,823.1nm, 402nm)飞秒脉冲激光系统自制的Nd:YVO4激光器输出532nm绿光激光,最高平均功率可达5.6W当用2.5W绿光激光泵浦时,从自制的钛宝石激光器及经BBO倍频可分别输出中心波长为823.1nm和402nm,平均功率300mW和73mW,谱宽32.3nm和5.1nm,脉宽22fs和33.3fs、重复率108MHz的近红外和蓝光激光整个系统具有结构紧凑、倍频效率高、运行稳定的特点.     

A detailed analysis of the photoemission spectra of basic thioaromatic monolayers on noble metal substrates

Analysis of photoemission spectra of complex thioaromatic self-assembled monolayers (SAMs) requires the knowledge and understanding of such spectra for the basic systems. Keeping this goal in mind, synchrotron-based high-resolution X-ray photoelectron spectroscopy was used to characterize SAMs formed from the simplest thioaromatic compounds, namely thiophenol, 1,1′-biphenyl-4-thiol and 1,1′;4′,1″-terphenyl-4-thiol on evaporated Au(1 1 1) and Ag(1 1 1) substrates. The acquired S 2p and C 1s spectra were analyzed in terms of fine structure and initial and final state effects in the photoemission process. The assignment of the individual spectral features was considered in detail. Conclusions on quality and chemical and structural homogeneity of the investigated SAMs were derived.     

Runge–Kutta interpolants for high precision computations

Runge–Kutta (RK) pairs furnish approximations of the solution of an initial value problem at discrete points in the interval of integration. Many techniques for enriching these methods with continuous approximations have been proposed. Here we construct C ¹ continuous, eighth and ninth order interpolation methods for a recently appeared RK pair of orders 9(8). These interpolants share a very small leading truncation error making them suitable for use at quadruple precision, i.e. 32–33 decimal digits of accuracy. Extended numerical results justify our effort.     

单模光纤中皮秒啁啾脉冲压缩

对单模光纤正群速色散区秒啁啾脉冲的非线性传进行了近似的解析分析和定量的数值计算。结果表明，负啁啾脉冲在传输过程中能得到有效压缩。压缩比与脉冲初始峰值功率和初始啁啾程度有关。初始峰值功率一定的脉冲，其压缩比随初始啁啾程度的增大面大，初始啁啾程度一定的脉冲，压缩比随初始峰值功率的增大而减小，表明自相位调制效应导致脉冲压缩效果变差。计算结果还表明，在脉冲时域宽度得到压缩的同时，光谱宽度也能得到同步压缩。     

Anisotropic elastodynamics in a half space: An analytic method for polynomial data

An initial boundary value problem for the dynamic system of anisotropic elasticity in a half space is studied in the paper. A novel method of finding an exact solution of this problem for a special polynomial form of initial data and inhomogeneous term of the system is described. On the base of this method the simulation of elastic waves in different homogeneous anisotropic half spaces is implemented.     

一类非线性发展方程整体弱解的存在性和稳定性

该文考虑一类新的非线性方程(｜ut｜r-2ut)t-Δutt-Δu-ρ(t)Δut=f(u) 的初边值问题，利用小扰动法证明了整体弱解的 存在性，借用位势井的概念得到了解的稳定性.〖HT5”H〗关键词:〖HT5”SS〗非线性发展方程;初边值问题;整体弱解;稳定性.     

On the optimization of the initial boundary value problem for a conservation law

In the present note, the theory of shift differentiability for the Cauchy problem is extended to the case of an initial boundary value problem for a conservation law. This result allows to exhibit an Euler-Lagrange equation to be satisfied by the extrema of integral functionals defined on the solutions of initial boundary value problems of this kind.     

On the concept of point value in the infinite-dimensional realization theory

In this article, we study the effect of the chosen representation of a point value (and point evaluation) on the class of periodic signals realizable using a certain type of infinite-dimensional linear system. By suitably representing the point evaluation at the origin in a Hilbert space, we are able to give a complete characterization of its extensions. These extensions involve a new concept called δ-sequence, the use of which as an observation operator of an infinite-dimensional linear system is studied in this article. In particular, we consider their use in the realization of periodic signals. We also investigate how the use of δ-sequences affects the convergence properties of such realizations; we consider the rate and character of convergence and the removal of the Gibbs phenomenon. As still a further demonstration of the significance of the chosen concept of a point value, we discuss the use of distributional point values in the realization of periodic distributions. The possible applications of this work lie in regulator problems of infinite-dimensional control theory, as is indicated by the well-known internal model principle.     

Plastic multipliers as driving variables of numerical simulation in elastoplasticity

Statics of elasto-plastic media is stated in terms of eigenstrains acting upon a background elastic problem with fixed (initial) stiffness. In order to minimize the number of unknowns and to provide computationally cheap algorithms plastic multipliers are used as main driving variables. Fixed-point type iterations are suggested for computing plastic multipliers within the load increment. Numerical experiments results are shown to be in good correlation with other software results. A range of problems is outlined where the usage of the proposed algorithms can be advantageous.     

解初值问题y″=g(x，y)的含参数块方法

1引言对于二阶常微分方程的初值问题y″=g(x,y),y(x_0)=y_0,y′(x_0)=y_0′,x_0(?)x(?)T(1)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提出二阶P-稳定方法和1978年G．Dahlquist证明P-稳定常系数线性多步方法的最高相容阶不超过2的重要结论以来,截止目前,已积累了许多高于2阶的P-稳定方法．例如,修正的Numerov方法,混合法(特殊形式RK的方法),多导法,Obrechkoff方法,显式RKN方法,单隐方法和对角隐式RKN方法等(顺便指出,文献[5,16]中所说的高阶方法的相容阶均不超过4)．所有这些方法,有些相