质子与裂变核238U反应的理论计算

利用球型光学模型、耦合道理论、核内级联、激子模型、蒸发模型、带宽度涨落修正的Hauser-Feshbach模型,Bohr-Wheeler裂变理论,对入射能量从阈能到200 MeV的p+²³⁸U各种反应进行了计算,计算结果和实验符合较好.     

Ce(Ⅳ)和Ce(Ⅲ)化合物系列的X射线光电子能谱研究

用XPS研究了标称四价铈盐系列:硫酸铈铵、硫酸铈、二苯基羟乙酸铈、碘酸铈、过氧化铈、二氧化铈以及三价铈盐系列:草酸亚铈、硫酸亚铈、二苯基羟乙酸亚铈、碘酸亚铈和氯化亚铈.结果表明,上述标称四价铈盐都属于混合价化合物,其Ce3d电子能谱呈现Ce⁴⁺和Ce³⁺的二组谱线结构的混合.在真空中加热后CeO₂的Ols电子能谱有两个氧峰,这说明 Ce(4f⁰)O(2p^π)←→Ce(4f¹)O(2p^n-1) 类型价态波动的可能性较大.三价铈盐的3d谱线的低结合能端约3.5—4eV处则存在摔落伴峰.     

非自治单种群时滞Kolmogorov系统的持续性和灭绝性

研究非自治单种群时滞Kolmogorov系统,给出了该系统中种群持续和灭绝的充分条件,这些结果与相应的非自治单种群Kolmogorov系统的有关结果相似.     

BOT项目中投标人管理水平的确定研究

在BOT项目中，项目公司在建设期和运营期的管理水平是非常重要的，其直接影响到项目的质量、维护成本和消费者的效用。本文根据政府和项目公司的博弈关系，通过建立动态博弈模型研究了在BOT项目中，项目公司应具备的管理水平。研究结果为政府在BOT项目招标过程中，确定投标人的管理水平资质提供理论依据。     

一类三阶牛顿变形方法

A class of third-order convergence methods of solving roots for non-linear equation,which are variant Newton's method,are given.Their convergence properties are proved.They are at least third order convergence near simple root and one order convergence near multiple roots.In the end,numerical tests are given and compared with other known Newton's methods.The results show that the proposed methods have some more advantages than others.They enrich the methods to find the roots of non-linear equations and they are important in both theory and application.     

一类带有Holling Ⅱ类功能性反应和相互干扰及脉冲效应的捕食系统

A kind of predator-prey system of Holling typeⅡand interaction perturbation with impulsive effect is presented.By using Floquet theory and small amplitude perturbations skills,the locally asymptotical stability of prey-eradication periodic solution and the permanence of the system are discussed and the corresponding threshold conditions are given respectively.Finally,the existence of positive periodic solution is investigated by the bifurcation theory.     

已有降维方法的推广

SAVE,PHD和SIRⅡ已被证明是有效的降维方法,这些方法基于下面的两个假设1线性条件和常数方差条件.但是,常数方差条件非常强.当常数方差不成立时,即使线性条件成立,SAVE,PHD和SIRⅡ经常会找到中心空间之外的方向.通过去掉了常数方差条件,在较弱条件下推广了SAVE,PHD和SIRⅡ从而使得在较弱的条件下,能得到中心空间的正确估计.     

Effect of Mg and C contents in MgCNi3, and structure and superconductivity of MgCNi3- x -Co x

The effect of Mg and C contents on T_C in MgCN₃, and structure and superconductivity of MgCNi_3-x Co _x were studied. It is found that the excess of Mg and C in initial material mixture is favorable to improvement inT _c and helps to obtain single-phase samples. For preparing MgCNi₃ superconductor, the optimum composition of starting materials is MgC_1.45Ni₃ with excess of Mg (20 wt.%) of the stoichiometric composition. In gCNi_3-x Co _x system, a continuous solid solution is formed, lattice parameter decreases slightly andT _c decreases obviously with increasingx. A suppression of superconductivity is observed due to the substitution of Co (Mn) for Ni. The suppression effect is smaller for the substitution of Co than that of Mn     

用于短波长FEL的光阴极微波电子枪设计研究

高增益、短波长自由电子激光器需要发射度低、峰值电流高的短脉冲电子束流.采用发射度补偿技术,设计了一台S波段、一个半腔体的光阴极微波电子枪以用于建议中的SDUV-FEL装置.POISSON,SUPERFISH和PARMELA程序的计算表明:当微脉冲电量为2nC时,这种设计能产生ε_n,rms=2.3π·mm·mrad、E_k=4.8MeV的电子束流.报道了该枪的设计考虑和模拟结果.