Bernfeld-Haddock猜想的推广形式及其证明

本文研究一类时滞微分方程解的收敛性,这类方程是Bernfeld和Haddock所提出的关于一个非线性时滞微分方程的每个解收敛于常数的一个猜想中的方程的推广形式,并具有重要的实际应用背景．首先给出例子说明几篇现有文献关于此类方程及其它的几种推广形式的解的收敛性证明中存在的错误．然后对这类方程解的收敛性在更弱的条件下给出了一个新的论证,修正并改进了已有的相应结论,也肯定了Bernfeld和Haddock猜想中结论的正确性．最后,由丁同仁教授撰写了一个附录,修正了在原有文献中对Bernfeld和Haddock猜想的证明中所出现的错误．     

含瞬时态、具有突变率的广义生-灭Q-矩阵(I)

研究含瞬时态、具有突变率的广义生-灭拟q-矩阵,给出易于验证的Q过程存在性准则,并构造出全部Q过程和全部诚实Q过程,证明了不需附加任何条件,所有诚实Q过程都是常返的,给出诚实Q过程是遍历的充要条件,并求出其遍历测度,以及证明了不存在可配称Q过程.最后给出两个例子以说明我们的结果易于验证.     

SUPERCONVERGENCE FOR L~2-PROJECTION IN FINITE ELEMENTS

Consider L~2-projection u_h of u to n-degree finite element space on one-dimensional uniform grids. Two different classes of the orthogonal expansion in an element for constructing a superclose to function u_h are proposed and then superconvergence for both u_h and Du_h are proved. When n is odd and no boundary conditions are prescribed, then u_h is of superconvergence at n+1 order Gauss points G_(n+1) in each element. When n is even and function values on the boundary are prescribed, then u_h is of superconvergence at n+1 order points Z_(n+1) in each element. If the other boundary conditions are given, then the conclusions are valid in all elements that its distance from the boundary≥ch|lnh|. The above conclusions are also valid. for n-dergree rectangular element Q_1 (n).     

ON GUNDERSEN''''S QUESTION FOR THE UNICITY OF MEROMORPHIC FUNCTIONS

The uniqueness of meromorphic functions that share four values are investigated, some results are obtained to show that if two nonconstant entire functions share three finite values IM, then the functions necessarily share all three values CM.     

Cell-SELEX-based aptamer-conjugated nanomaterials for enhanced targeting of cancer cells

Early detection and treatment of cancer depends on developing highly sensitive and specific methods for targeting cancer cells. To do this, aptamers, which are generated by a novel technique called cell-SELEX (systematic evolution of ligands by exponential enrichment), have been widely applied in cancer cell targeting based on such merits as high target affinity and specificity, small size, minimal immunogenicity, and ease of chemical modification. Furthermore, aptamers can gain more flexibility as cancer c...     

Kinetics analysis of chemiluminescence in discharge-driven HF chemical lasers

The chemiluminescence spectrum in the optical cavity of discharge-driven hydrogen ?uoride(HF) chemical laser is measured.The result reveals that the spectra of the helium and fluorine(F) atoms are the major components.Moreover,the green chemiluminescence in the downstream of the optical axis is mostly composed of the 60P20 spectral line of the HF molecule.The analysis shows that,except for the cold pumping reaction,the recombination of the F atoms and the hot pumping reaction also occur in the optical cavity.Due to the hot pumping reaction and the optical cavity temperature in a specific range,the 60P20 line becomes the strongest HF molecule in the downstream region of the optical axis.After the hot pumping reaction,the green chemiluminescence always appears in the downstream region of the optical axis when the optical cavity temperature varies in a greater range.     

The effect of boron on the electronic structure of dislocation in NiAl

The segregation effect of B on the [100](010) edge dislocation core in NiAl single crystals is investigated using the DMol method and the discrete variational method within the framework of density functional theory. The impurity segregation energy and the charge distribution are calculated. The effects of B on the dislocation motion are discussed. The results show that B prefers to segregate at the Center-Al dislocation core. Moreover, B forms strong bonding states with its neighboring host atoms, which ma...     

一种新型直流混合型HTSCFCL的研究

在研究混合型高温超导限流器和失超桥式整流型高温超导限流器原理的基础上,提出了一种新型单相混合型高温超导限流器,利用MATLAB进行仿真研究,结果表明该限流器设计参数准确,限流效果明显.新型直流混合型HTSCFCL的研究对限制短路电流和提高系统稳定运行具有十分重要的意义.     

A RESULT ONPERIODIC SOLUTIONS OF SECOND ORDER FUNCTIONAL DIFFERENTIAL EQUATIONS

We obtain sufficient condition for the existence of periodic solutions of thefollowing second order functional differential equationsx"(t) + ax'~α(t) + bf(x(t)) + g(x(t-T_1), x'(t-T_2))=p(t)=p(t+2π).Our approach is based on the continuation theorem of coincidence degree, andthe α-priori: estimate of periodic solutions.     

STRENGTH CRITERION FOR PLAIN CONCRETE UNDER MULTIAXIAL STRESS BASED ON DAMAGE POISSON’S RATIO

A new unified strength criterion in the principal stress space has been proposedfor use with normal strength concrete (NC) and high strength concrete (HSC) in compression-compression-tension, compression-tension-tension, triaxial tension, and biaxial stress states. Thestudy covers concrete with strengths ranging from 20 to 130 MPa. The conception of damagePoisson's ratio is defined and the expression for damage Poisson's ratio is determined basically.The failure mechanism of concrete is illustrated, which points out that damage Poisson's ratiois the key to determining the failure of concrete. Furthermore, for the concrete under biaxialstress conditions, the unified strength criterion is simplified and a simplified strength criterion inthe form of curves is also proposed. The strength criterion is physically meaningful and easy tocalculate, which can be applied to analytic solution and numerical solution of concrete structures.