烷基苯酚类化合物的气相色谱保留值与其结构参数的定量关系

计算了44个烷基苯酚类化合物的组成、拓扑、几何、静电和量子化学等结构参数,运用启发式方法对这些结构参数进行筛选,得到了含3个变量的化合物的定量结构与色谱保留值的线性关系模型,同时以这3个变量作为支持向量机模型的输入变量建立非线性回归模型。两种方法的相关系数(R2 )分别为0.98和0.92,相应的均方根误差分别是0.99和2.77。通过对两种模型的稳定性和预测能力的比较,发现线性模型能够更好地反映烷基苯酚的气相色谱保留值与其结构参数之间的定量关系。在已知烷基苯酚类化合物结构参数的情况下,线性回归模型更有助于它们的色谱分析。     

Quantum Euler-Poisson System: Local Existence of Solutions

The one-dimensional transient quantum Euler-Poisson system for semiconductors is studied in a bounded interval. The quantum correction can be interpreted as a dispersive regularization of the classical hydrodynamic equations and mechanical effects. The existence and uniqueness of local-in-time solutions are proved with lower regularity and without the restriction on the smallness of velocity, where the pressure-density is general (can be non-convex or non-monotone).     

On the stability of solutions to quadratic programming problems

We consider the parametric programming problem (Q _p ) of minimizing the quadratic function f(x,p):=x ^T Ax+b ^T x subject to the constraint Cx≤d, where x∈ℝ ⁿ , A∈ℝ ^n×n , b∈ℝ ⁿ , C∈ℝ ^m×n , d∈ℝ ^m , and p:=(A,b,C,d) is the parameter. Here, the matrix A is not assumed to be positive semidefinite. The set of the global minimizers and the set of the local minimizers to (Q _p ) are denoted by M(p) and M ^loc (p), respectively. It is proved that if the point-to-set mapping M ^loc (·) is lower semicontinuous at p then M ^loc (p) is a nonempty set which consists of at most ? _m,n points, where ? _m,n = is the maximal cardinality of the antichains of distinct subsets of {1,2,...,m} which have at most n elements. It is proved also that the lower semicontinuity of M(·) at p implies that M(p) is a singleton. Under some regularity assumption, these necessary conditions become the sufficient ones. Received: November 5, 1997 / Accepted: September 12, 2000?Published online November 17, 2000     

一类非线性压缩生成的不变集的局部维数

本文以有界变差原理和有界畸变原理为工具,讨论了满足开集条件,且二次可微的一族递增的非线性压缩映射所产生的不变集的局部维数。     

State-Dependent Coupling in General Networks

In this paper we extend a result which holds for the class of networks of quasireversible nodes to a class of networks constructed by coupling Markov chains. We begin with a network in which the transition rates governing the stochastic behaviour of the individual nodes depend only on the state of the node. Assuming that the network has an invariant measure, we construct another network with transition rates at each node depending on the state of the entire network, and obtain its invariant measure.     

Estimation of Macrodispersion by Different Approximation Methods for Flow and Transport in Randomly Heterogeneous Media

We present two- and three-dimensional calculations for the longitudinal and transverse macrodispersion coefficient for conservative solutes derived by particle tracking in a velocity field which is based on the linearized flow equation. The simulations were performed upto 5000 correlation lengths in order to reach the asymptotic regime. We used a simulation method which does not need any grid and therefore allows simulations of very large transport times and distances.Our findings are compared with results obtained from linearized transport, from Corrsin's Conjecture and from renormalization group methods. All calculations are performed with and without local dispersion. The variance of the logarithm of the hydraulic conductivity field was chosen to be one to investigate realistic model cases.While in two dimensions the linear transport approximation seems to be very good even for this high variance of the logarithmic hydraulic conductivity, in three dimensions renormalization group results are closer to the numerical calculations. Here Dagan's theory and the theory of Gelhar and Axness underestimate the transverse macrodispersion by far. Corrsin's Conjecture always overestimates the transverse dispersion. Local dispersion does not significantly influence the asymptotic behavior of the various approximations examined for two-dimensional and three-dimensional calculations.     

The Local Conditional Stability Estimate for an Inverse Contact Problem in the Elasticity

In this paper, we consider an inverse problem in elasticity of determining stress on a contact domain from measurements outside the contact domain. The local conditional stability estimate for determining the stress vector is obtained. This conditional stability can give the convergence rate for Tikhonov's regularized solutions. This revised version was published online in July 2006 with corrections to the Cover Date.     

壁湍流结构的二维子波分析

对槽道湍流直接数值模拟的脉动速度场进行了二维子波分析。研究了近壁区低速条带结构的多尺度特性。利用定义的局部雷诺应力测度结合平坦因子的方法对湍流脉动速度分解,得到脉动速度的间歇成份和高斯成份。用局部雷诺应力测度正的峰值为特征,通过条件统计平均,得到近壁区典型的拟序结构。     

Experiments on the Magnetism of Sc Implanted into Metals

The study of dilute Sc impurities in either heavier d-transition metals or in alkali metal hosts is difficult due to their limited solubility; however, the large host-impurity mismatch in these systems makes them particularly interesting in terms of local electronic structure. One way to overcome the solubility problem is implantation into the desired host; in particular, using recoil implantation following heavy-ion nuclear reactions, deep implantation into practically any host can be achieved. Here, we compare the implantation of ⁴³Sc into Cs, studied in situ by the in-beam TDPAD method [1], with the implantation of ^44m Sc into Fe, studied by low-temperature nuclear orientation (LTNO) and related techniques (NMRON, thermal cycling) [2].     

大口径非球面精磨表面形状检测技术研究

介绍了一种大相对口径非球面精磨阶段面形的测量方法原理及实现其功能的软件设计。利用机械接触式装置 ,通过长导轨及其光栅探头的高度变化来直接测量非球面的矢高 ,并把所测得的三维数据传输给计算机。经数据修正和预处理 ,通过MATLAB软件计算得到整个镜子的面形特征参数。其结果用来指导大口径非球面的精磨加工。