带有再生养分流的海洋生物群落的生长模型及其渐近性态

本文建立了具有一般养分吸收功能的多种海洋生物种群的生长模型,各种群为了争夺共同的资源而竞争,外界资源供给增量是时间的有界函数,一般地带有滞后的再生养分流补充,并且考虑各种群间竞争因素和每个种群内部的干扰因素。该文讨论了模型的有界性,并证明了当干扰常数m<1时,所考虑的生物群落是永久持续生存的,即每个种群都有正的上下限,当m=1时,在再生养分无滞后时建立了若干种群灭绝的充分条件和持续生存的必要条件。     

一类带奇异低阶项椭圆型方程的正则性

本文得到了一类带奇异低阶项椭圆方程的一个正则性结果.方程形式为Lu+ vu=μ,其中L为二阶散度型椭圆算子,v属于某一Morrey空间,μ为一非负Radon 测度.     

W 2,p -a priori estimates for the emergent Poincaré Problem

We derive W ^2,p (Ω)-a priori estimates with arbitrary p ∈(1, ∞), for the solutions of a degenerate oblique derivative problem for linear uniformly elliptic operators with low regular coefficients. The boundary operator is given in terms of directional derivative with respect to a vector field ℓ that is tangent to ∂Ω at the points of a non-empty set ε ⊂ ∂Ω and is of emergent type on ∂Ω.      

具饱和传染率的脉冲免疫接种SIRS模型

研究了具饱和传染率的脉冲免疫接种SIRS模型的一致持续生存和周期解,得到了无病周期解全局渐近稳定的充分条件和系统一致持续生存的充分条件,并应用分支理论得到了正周期解存在的分支参数.     

Simultaneous optimality of LSE and ANOVA estimate in general mixed models

Problems of the simultaneous optimal estimates and the optimal tests in general mixed models are considered. A necessary and sufficient condition is presented for the least squares estimate of the fixed effects and the analysis of variance （Hendreson III＇s） estimate of variance components being uniformly minimum variance unbiased estimates simultaneously. This result can be applied to the problems of finding uniformly optimal unbiased tests and uniformly most accurate unbiased confidential interval on parameters of interest, and for finding equivalences of several common estimates of variance components.     

α混合序列下的核密度估计量的相合性

本文在α-混合序列下,讨论了核密度估计量的强相合性与一致强相合性,并给出其收敛速度.这些结论改进了Bosq(1998)中引理2.1和定理2.1所获得的相应结论.     

硼酸掺量对SrAl2O4长余辉发光材料的发光性能影响

用燃烧法制备了Eu2 ,Dy3 共掺杂SrAl2O4长余辉发光材料,研究了不同硼酸掺量对Eu2 ,Dy3 共掺杂SrAl2O4长余辉发光材料发光性能的影响。为了分析B2O3在材料制备中的作用,用XRD对所合成材料进行物相分析,用荧光光谱仪记录其发射光谱,并在暗室里拍摄紫外激发下的发光照片。结果表明:硼酸掺量为0.8的样品的发光光谱,其发射峰峰值位于518 nm,是典型的Eu2 的4f5d→4f的特征发射,为一宽谱带发光光谱。硼酸掺量为2的样品的发光光谱,其在518 nm位置的峰十分弱,而在487 nm处同时出现了一个弱峰,整个谱线呈一斜坡状。随着硼酸加入量的不同,Eu2 ,Dy3 共掺杂铝酸锶的发光效果、形貌特征均不同。在某一范围内,随着硼酸添加量的增加,合成了发光主晶相,烧结温度有所降低,材料的发光性能和发光亮度均有所提高。     

Valuation of cash flows under random rates of interest: A linear algebraic approach

This paper reformulates the classical problem of cash flow valuation under stochastic discount factors into a system of linear equations with random perturbations. Using convergence results, a sequence of uniform approximations is developed. The new formulation leads to a general framework for deriving approximate statistics of cash flows for a broad class of models of stochastic interest rate process. We show applications of the proposed method by pricing default-free and defaultable cash flows. The methodology developed in this paper is applicable to a variety of uncertain cash flow analysis problems.     

On the exponential stability of dynamic equations on time scales

In this paper, we deal with some theorems on the exponential stability of trivial solution of time-varying non-regressive dynamic equation on time scales with bounded graininess. In particular, well-known Perron's theorem is generalized on time scales. Under rather restrictive condition, that is, integral boundedness of coefficient operators, we obtain a characterization of the uniformly exponential stability.