求解一维非线性扩散Fisher方程

在再生核空间W[D]中研究一维非线性扩散Fisher方程的数值逼近方法,给出了此方程的精确解的级数表达式,并证明了其近似解一致收敛到精确解.数值算例充分验证了算法的有效性.     

The explanatory role of abstraction processes in models: The case of aggregations

Though it is held that some models in science have explanatory value, there is no conclusive agreement on what provides them with this value. One common view is that models have explanatory value vis-à-vis some target systems because they are developed using an abstraction process (i.e., a process which involves omitting features). Though I think this is correct, I believe it is not the whole picture. In this paper, I argue that, in addition to the well-known process of abstraction understood as an omission of features or information, there is also a family of abstraction processes that involve aggregation of features or information and that these processes play an important role in endowing the models they are used to build with explanatory value. After offering a taxonomy of abstraction processes involving aggregation, I show by considering in detail several models drawn from different sciences that the abstraction processes involving aggregation that are used to build these models are responsible (at least partially) for their having explanatory value.     

苏锡常地区优势产品农业产业化地域模式

苏锡常地区是我国富庶的农业地区，依据实地调研、分析农业比较优势，该地区农业产业化经营应具有较强支撑力度的优势产品，较高的产业关联度，较高的科技含量。着重研究两种域模式，一是基于名特优农产品的，较高的产业关联度，较高的科技含量，着重研究两种地域模式，一是基于名特优农产品的“（凭借）小品种、（创造）高效益、（占领）大市场”的模式；二是由龙头加工企业带动，体现优势产品创造高效益、加工产品提高附加值、产业扩张开拓大市场的模式，进而探讨上述地域模式的集聚－扩散机制、苏锡常地区农业产业化经营在地域上表现出集聚为主的特点，随着优势区域的实力增强而出现扩张的趋势，通过产业扩张，市场扩张、地域扩张，在更大范围内实现生要素优化组合。     

Exponential convergence of fisher entropy for diffusion processes

In this paper, we introduce the definition of Γ-Fisher entropy. For the stochastic differential equation in Rd and the unique invariant probability measure μ, we obtain the exponential convergence of Γ-Fisher entropy with respect to μ under some condition about Γ and the drift b. Moreover, we revisit the exponential convergence of the usual Fisher entropy under the Bakry Emery condition.     

h-条件扩散的特性

对一般二阶椭园型算子，讨论了ｈ－条件扩散的鞅特征及条件生命时，并对条件Ｆｅｙｎｍａｎ－Ｋａｃ泛函进行了研究，这样，就把相关的问题推广到了一般椭园型算子。     

自旋阀结构多层膜的热稳定性

研究了Si／Ta／NiFe／Cu／NiFe／FeMn／Ta结构的自旋阀的热稳定性及层间扩散问题．高分辨电镜（HREM）观察表明，各层呈柱状晶生长．低于200°C退火能有效地提高钉扎场．高于200°C退火后，钉扎场下降，300°C时降为零．利用俄欧电子能谱仪（AES）研究了在相同的条件下制备的基片／Ta／NiFe／FeMn／Ta结构多层膜．结果表明，200°C以下时薄膜层之间主要发生沿晶界的扩散，300°C时体扩散的作用不能忽略．     

Persistence and Global Stability for Two-Species Predator-Prey System With Diffusion

1　IntroductionOneofthemostinterestingquestionsinmathematicalbiologyconcernsthesurvivalofspeciesinecologicalmodels.Inthispaper,weconsideranonautonomoussystemcomposedoftwospeciespredator-preywithdiffusion.Levin[1]firstestablishedthiskindofmode-labouta...     

针对细分方案的快速FBM算法

在对分数布朗运动进行理论研究的基础上，给出了一种针对细分方案的快速ＦＢＭ算法，即对于不同格式的剖分，填加相应的型值点，以实时地生成各种不同ＦＢＭ或者类ＦＢＭ曲线，此法可以有效地用于各种复杂曲线及边界线模拟。     

有限变形理论的若干进展及其在流体力学中的相关应用

概要性地叙述了作者新近提出的"当前物理构型对应之曲线坐标系显含时间的有限变形理论"、"几何形态为曲面的连续介质的有限变形理论",前者针对介质几何形态为Euclid流形(体积形态),后者针对Riemann流形(曲面形态).类比于一般有限变形理论,上述理论均包括物理及参数构型构造,变形梯度定义及其基本性质,变形刻画,输运定理以及守恒律方程.基于上述理论提出对应曲线坐标系显含时间的流函数涡量解法,固定曲面上二维不可压缩流动的流函数涡量解法以及海面油污扩散控制方程,并给出了相关数值研究结果.     

掺杂球形氢氧化镍的循环伏安特性

采用循环伏安法研究了Ｎｉ（ＯＨ）２粉末微电极，认为Ｎｉ（ＯＨ）２粉末微电极电化学过程是一个准可逆过程且电极反应在Ｎｉ（ＯＨ）２／ＮｉＯＨ之间进行；研究了阳极过程中掺杂元素对Ｎｉ（ＯＨ）２质子扩散系数的影响，发现掺Ｃｏ后比纯Ｎｉ（ＯＨ）２的扩散系数提高近１倍，而掺Ｚｎ后则扩散系数有所降低，掺Ｃｏ和Ｚｎ后Ｎｉ（ＯＨ）２电极氧的析出电位均比纯Ｎｉ（ＯＨ）２的氧的析出电位有所提高。