La_(0.7-x)Gd_xSr_(0.3)MnO_3(x=0.20,0.30,0.40,0.50)的TCR研究(英文)

研究了La位Gd掺杂对La0.7-xGdxSr0.3MnO3(x=0.20,0.30,0.40,0.50)体系的电阻温度系数(TCR)的影响.实验结果表明:Gd掺杂将引起电阻率曲线的急剧变化,导致出现大的TCR;而且随Gd掺杂的增加,TCR在x=0.30出现峰值,然后随掺杂量增加逐步降低.体系出现大的TCR,来源于Gd掺杂引起的额外磁性耦合.     

用圆的极坐标方程证明定值问题

高中新课程把极坐标内容列入选修系列4,极坐标的应用又成为高中数学的热点．笔者主要介绍“圆心在（a,0）,半径为a的圆的极坐标方程ρ=2acosθ”在几何定值证明中的应用,供高中数学教师阅读时参考．     

Euclid(Φ~4)_4场的白噪声方法

在白噪声分析框架下构造了λ44广义泛函,定义了其相应的Schwinger函数,验证了它满足除反射正性之外的全部OS公理,并回顾了Euclid随机场理论的进展和一些问题.     

Modified characteristic finite difference fractional step method for moving boundary value problem of nonlinear percolation system

A fractional step scheme with modified characteristic finite differences running in a parallel arithmetic is presented to simulate a nonlinear percolation system of multilayer dynamics of fluids in a porous medium with moving boundary values. With the help of theoretical techniques including the change of regions, piecewise threefold quadratic interpolation, calculus of variations, multiplicative commutation rule of difference operators, multiplicative commutation rule of difference operators, decomposition of high order difference operators, induction hypothesis, and prior estimates, an optimal order in l ² norm is displayed to complete the convergence analysis of the numerical algorithm. Some numerical results arising in the actual simulation of migration-accumulation of oil resources by this method are listed in the last section.     

渗流耦合系统动边值问题特征分数步差分方法

对多层渗流方程耦合系统动边值问题,提出适合并行计算的一类特征分数步差分格式,利用区域变换、变分形式、粗细网格配套、乘积型叁二次插值、差分算子乘积交换性、高阶差分算子的分解、先验估计的理论和技巧,得到收敛性的最佳阶l2误差估计．该方法已成功地应用到多层油资源运移聚集的资源评估生产实际中,得到了很好的数值模拟结果．     

梳型聚合物在固液界面吸附形态的Monte Carlo模拟

采用Monte Carlo模拟方法对PAA/PEO梳型聚合物在固液界面吸附形态进行了模拟,得到了聚合物在液相中聚集形态以及在固液界面上吸附形态的瞬时构型,同时获得了聚合物的吸附层厚度、均方回转半径和吸附在固液界面的各种链段数等微观信息. 结果证实：随着聚合物的接枝数Np增大,聚合物在液相中的扩散系数逐渐降低、相对粘度逐渐增大;当Np≥6时,羧基阴离子基团置于吸附层最外围,吸附层厚度近似等于PEO侧链长度,聚合物在固体表面形成空间排斥为主、静电排斥为辅的吸附状态;吸附聚合物分子密度过低或过高均不能起到良好的空间屏蔽或阻隔效应;吸附在固体粒子表面聚合物应该具有适宜的吸附-脱附自平衡能力.     

Radiation energy flux of Dirac field of static spherically symmetric black holes

By the statistical entropy of the Dirac field of the static spherically symmetric black hole, the result is obtained that the radiation energy flux of the black hole is proportional to the quartic of the temperature of its event horizon. That is, the thermal radiation of the black hole always satisfies the generalised Stenfan--Boltzmann law. The derived generalised Stenfan--Boltzmann coefficient is no longer a constant. When the cut-off distance and the thin film thickness are both fixed, it is a proportional coefficient related to the space--time metric near the event horizon and the average radial effusion velocity of the radiation particles from the thin film. Finally, the radiation energy fluxes and the radiation powers of the Schwarzschild black hole and the Reissner--Nordstrõm black hole are derived, separately.     

Upwind finite difference method for miscible oil and water displacement problem with moving boundary values

The research of the miscible oil and water displacement problem with moving boundary values is of great value to the history of oil-gas transport and accumulation in the basin evolution as well as to the rational evaluation in prospecting and exploiting oil-gas resources. The mathematical model can be described as a coupled system of nonlinear partial differential equations with moving boundary values. For the twodimensional bounded region, the upwind finite difference schemes are proposed. Some techniques, such as the calculus of variations, the change of variables, and the theory of a priori estimates, are used. The optimal orderl2-norm estimates are derived for the errors in the approximate solutions. The research is important both theoretically and practically for the model analysis in the field, the model numerical method, and the software development.     

多层油资源运移聚集的数值模拟和实际应用

研究了三维问题的石油地质和渗流力学特征。提出了数学模型,构造了新的算子分裂隐式迭代格式,并成功地对胜利油田东营凹陷(厚层)和惠民凹陷(多层)带断层和通道的实际问题进行了大规的数值模拟计算。计算结果在油藏位置等方面和实际情况相吻合,完整地解决了这一石油地质和渗流力学的国际着名问题。     

离子伯恩斯坦波对低杂波驱动电流影响的研究

利用改进的二维Fokker-Planck方程和低杂波射线轨迹程序研究了在低杂波和离子伯恩斯坦波协同作用下低杂波的功率沉积分布、驱动电流分布。数值结果显示在两波协同作用下低杂波驱动非感应电流的效率得到了很大的改善。