红外热像仪参数的双黑体测量装置

对红外热像仪参数双黑体测量装置的工作原理进行了介绍。装置采用双黑体及反射型靶标为温差辐射源，可实现黑体温度温差准直辐射的定期校准和红外热像仪参数测量量值的溯源，也可实现红外热像仪参数的可控性，以及对它进行稳定的、可复现的精确测量。推导出利用红外热像仪参数双黑体测量装置测量信号传递函数SiTF数学模型，分析了红外热像仪参数测量装置的客观因素——仪器常数，针对仪器常数对SiTF测量的影响进行了试验。试验结果表明，仪器常数对红外热像仪SiTF参数测量精度影响较大，并同时影响时域与空域NETD及3D噪声的准确测量。     

迈克尔逊干涉仪中补偿板与干涉条纹

通过分析缺失补偿板的迈克尔逊干涉仪中的附加光程差,推出干涉条纹满足的方程式,并用计算机模拟了动镜移动过程中变化的干涉条纹,与实验结果相一致.     

Instabilities in the Chapman-Enskog Expansion and Hyperbolic Burnett Equations

It is well-known that the classical Chapman-Enskog procedure does not work at the level of Burnett equations (the next step after the Navier-Stokes equations). Roughly speaking, the reason is that the solutions of higher equations of hydrodynamics (Burnett's, etc.) become unstable with respect to short-wave perturbations. This problem was recently attacked by several authors who proposed different ways to deal with it. We present in this paper one of possible alternatives. First we deduce a criterion for hyperbolicity of Burnett equations for the general molecular model and show that this criterion is not fulfilled in most typical cases. Then we discuss in more detail the problem of truncation of the Chapman-Enskog expansion and show that the way of truncation is not unique. The general idea of changes of coordinates (based on analogy with the theory of dynamical systems) leads finally to nonlinear Hyperbolic Burnett Equations (HBEs) without using any information beyond the classical Burnett equations. It is proved that HBEs satisfy the linearized H-theorem. The linear version of the problem is studied in more detail, the complete Chapman-Enskog expansion is given for the linear case. A simplified proof of the Slemrod identity for Burnett coefficients is also given.     

鞅差序列的Bernstein型不等式及其应用

本文将独立随机变量序列的Bernstein型不等式推广到鞅差序列情形,给出该不等式的一个应用,并在一定条件下证明了非参数回归中函数估计的强相合性.     

TWO-POINT BOUNDARY VALUE PROBLEM FOR A CLASS OF SECOND-ORDER DIFFERENCE EQUATIONS

In this paper, we apply a critical point theorem and obtain the condition for the existence of three solutions to two-point boundary value problem of a second order nonlinear difference equation.     

Geometry of Differential Equations: A Concise Introduction

A short introduction to geometrical theory of nonlinear differential equations is given to provide a unified overview to the collection 'Symmetries of differential equations and related topics'.     

ON A LINEAR DELAY DIFFERENCE EQUATION WITH IMPULSES

IIntroductlonLet N denote the set of all Integers．FOr any a;b E N,define N(a)＝{a,a＋1,…},N(a,b)二{a,a＋1,…,b}when a＜b．Consider the dlf卜巳renceequationl 凸x。＋P。x。－。＝0;nEN(0)andN4n。;2—“－””’”门二l0 凸X。,＝~X。,,JENO);where A denotes the forward difference operator八。。＝x。＋l一 x。,{P。} Isa sequence ofnon－negative real numbers,{nj}Is a sequence ofnon－negativeIntegers with nj＜nj＋lfor j E N(1)and nj一 co as ;一 co,{4}Is a sequence。I优。且皿mb ers,…     

Coupled intervals in the discrete calculus of variations: necessity and sufficiency

In this work we study nonnegativity and positivity of a discrete quadratic functional with separately varying endpoints. We introduce a notion of an interval coupled with 0, and hence, extend the notion of conjugate interval to 0 from the case of fixed to variable endpoint(s). We show that the nonnegativity of the discrete quadratic functional is equivalent to each of the following conditions: The nonexistence of intervals coupled with 0, the existence of a solution to Riccati matrix equation and its boundary conditions. Natural strengthening of each of these conditions yields a characterization of the positivity of the discrete quadratic functional. Since the quadratic functional under consideration could be a second variation of a discrete calculus of variations problem with varying endpoints, we apply our results to obtain necessary and sufficient optimality conditions for such problems. This paper generalizes our recent work in [R. Hilscher, V. Zeidan, Comput. Math. Appl., to appear], where the right endpoint is fixed.     

Finite Element Solution of Conical Diffraction Problems

This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R ² coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis.