扩散

However, the refraction of plane wave in reaction-diffusion system obeys Snell's law only for proper diffusion coefficients and system parameters.

在二维复金兹堡-朗道方程描述的反应扩散振荡系统中，就扩散对平面波折射率的影响进行了数值研究，从Snell定律出发导出了折射率的解析表达式，数值和理论结果表明：在纯扩散情况下，平面波的折射满足Snell折射定律，扩散只影响着平面波折射率的大小；在同时存在反应扩散情况下，只有在适当的扩散系数和系统参数下，平面波的折射才满足Snell折射定律。

Simultaneity, the adsorption energies of single Si adatom on the H-terminated Si (100) surfaces are specially mapped out in this paper, from which the favorite binding sites and possible diffusion pathways have been achieved. The variety of the diffusion anisotropy with the coverage transforming is obtained. The energy barriers of the adatom diffusion are found to be higher than that on the clean surface, because the H atoms saturate the dangling bonds of the surface Si atoms.

同时，本文研究了附加硅原子在理想H-terminated Si(100)表面的沉积扩散行为，计算得到了一系列沉积点和可能的扩散路径；讨论分析了扩散行为的各向异性以及氢覆盖率对各向异性影响的规律，并且发现附加硅原子在H-terminated Si(100)表面上的扩散势垒比在清洁Si(100)表面上的高，我们认为这主要是因为氢原子饱和了表面上硅原子的悬挂键，提高了扩散势垒。

The effect of thermal difffusion on electrical properies of SrTiO_3multi-func-tion ceramics with coation ion was studied by application of the even design experimental method. Microstructure were investigated by SEM and TEM. Element analysis were examined by EPA and EDX techenolegy. No new intergranuar phrase were observed. The relationship amang electrical properties,diffusion conditions of the materials were discussed.

采用均匀设计液相涂覆热扩散方法，研究了涂覆离子，热扩散条件等对SrTiO_3系陶瓷电性能的影响；用扫描电子显微镜和透射电子显微镜作微观分析，用X射线能谱仪和电子探针作元素分析，证实钠离子的涂覆热扩散未在陶瓷晶粒之间产生新相，钠离子在晶粒内表面形成了一扩散层，讨论了扩散条件与电性能的内在联系。

The effect of thermal diffusion on electrical properies of SrTiO3 multi-function ceramics with coating ion was studied by application of the even design expermental method. Microstructure and element analysis were examined by SEM and Energy-Dispersive X-Ray analyss techenolegy. No new intergranuar phrase were oberved.The relationship amang electrical properties,diffusion conditions of the materials were discussed.

采用均匀设计液相涂覆热扩散方法，研究了涂覆离子，热扩散条件等对SrTiO3系陶瓷电性能的影响；用扫描电子显微镜作微观分析，X射线能谱仪作元素分析，证实钠离子的涂覆热扩散未在陶瓷晶粒之间产生新相，钠离子在晶粒内表面形成了一扩散层，讨论了扩散条件与电性能的内在联系。

The results show that the main CO proliferation forms in coal bed are the Knudsen proliferation and the transition proliferation.

结果表明，CO在煤层中的扩散主要为Knudsen扩散及过渡型扩散方式，过渡孔的增加有利于其扩散，而微孔的增加则不利于其扩散。

It has been found that the cation exchange on diffusivity may play the role in different ways for different zeolites. When the diameter of the diffusant molecule is much smaller than the pore or cage size of the zeolite, the influence of exchanged cations is mainly by way of altering the electric field intensity (or the density of electric charge), the large the Z/r of the exchanged cations, the smaller the diffusivity; while the diameter of the molecule is apporsi- mately equal to the pore or channel size of the zeolite, the exchanged cations may affect the diffusivity by means of blocking up or narrowing the channels of the zeolite.

金属阳离子交换对扩散的影响表现为：当扩散分子的直径比分子筛孔道直径小得多时，交换阳离子以改变分子筛内部电场强度或电荷密度的方式影响扩散速度，阳离子的Z/r越大，扩散系数越小；当扩散分子直径与分子筛孔道直径相近时，交换阳离子则因堵塞或窄化孔道而改变分子的扩散速度。

The uniphase C with W/≤0.3 can be synthesized without being preheated. When W/ is higher than 0.3, the sample expansion increases with the increase of W content, the reaction between W and C is incomplete, the combustion products consist of W〓C, WC, TiC, C, and unreacted W. Preheating mixtures can accelerate the completion of the reaction among Ti, W, and C. The uniphase C with W/=0.4 can be synthesized by SHS at preheat temperature of 600℃. There are two kinds of powders with size of 2-4μm and size less than 1μm in the combustion products.

通过燃烧前沿激冷淬熄试验及产物形貌特征（燃烧块断面组织和产物多晶聚合体颗粒）分析，创新性地提出了两种体系的自蔓延高温反应机制。1熔化—溶解—析出机制：当燃烧温度较高时，燃烧前沿Ti粉熔化，W和C溶解于熔融Ti里，而后C从熔融里析出。2扩散—固溶机制：当燃烧温度不足以使燃烧前沿Ti粉熔化时，通过C的扩散先形成TiC层，其后C沿着热应力导致的TiC层裂纹继续扩散，与固态Ti核反应生成TiC；同时，C扩散至W颗粒，形成W〓C，而后通过C的继续扩散W〓C转变成WC；与此同时，WC固溶至TiC里，形成C固溶体。

This thesis consists of three chapters .In chapter one , the distributions of the last exit time and the corresponding results of Brownian motion in Markov process are introduced ,and previous remarkable achievements on the excursion of Brownian motion are numerated too ,also ,we introduce the main results and the history of elliptic diffusion process; In chapter two ,we summarily describe the excursion in Markov process and the result of the first hitting time of the elliptic diffusion process ; In last chapter ,we study estimates for the distributions of above three maximum excursions and minimum excursion in the elliptic diffusion process on R (d≥3), which leads the excursion of Brownian motion on ball on R (d≥3) to become a particular case .

全文共分三章，第一章介绍对称Markov过程中布朗运动的未离时分布及相关研究结果，列举了前人对布朗运动的游程问题的研究成果，并用较多篇幅介绍了一类特殊且非常重要的扩散过程——一致椭圆扩散过程的研究历史和本文的主要研究结果；第二章介绍Markov过程有关停时及游程的概念，叙述了一致椭圆扩散过程的定义，并给出了一致椭圆扩散过程有关首中时的结果；第三章是本文的核心部分，详细讨论了暂留一致椭圆扩散过程关于R~d(d≥3)上球的三类极大游程和极小游程的分布估计，使得布朗运动关于球的游程问题成为特例。

The mechanism and the physical model of the developing process of rafted γ′ during HIP and the relationship of the rafted γ′ piece width to original size、volume fraction and the elements diffusion flux of γ′ were detailed discussed.

首次比较研究了两种合金经HIP和热处理后，扩散偶中元素的扩散规律，并定量计算了Al、Ta和W元素的扩散流量、扩散系数和扩散深度；系统地揭示了结合界面处的组织结构、形成机理及性能的变化规律。

Based on the above-mentioned parameter, according to the relationship between robust estimation and nonlinear diffusion, the Turkey loss function is introduced as the diffusion function in SAR image decomposition because of its better performance, and the contour of an image is extracted by the Turkey diffusion function with the proposed diffusion parameter mentioned above. The experiment results indicate that the Turkey loss function based diffusion process can strengthen the conspicuous contour. Additionally, a Raita\'s criterion-based method, solving the automatic diffusion threshold, is proposed to automatically set the threshold in diffusion decomposition.

针对基于梯度参数和局域方差系数的扩散在对SAR图像进行分解时存在的缺陷，提出了一种局域方差系数与窗口幅度均值积的扩散系数，该系数能够更有效地实现潜在目标区域和背景区域的区分；在此基础上，根据鲁棒估计与非线性扩散的联系，引入扩散效果更好的Turkey损失函数作为图像分解中的扩散函数，并结合局域方差系数与窗口幅度均值积的扩散参数来提取图像的轮廓，结果表明：基于Turkey损失函数的扩散过程对特征突出的边缘所起的&强化作用&更加明显；此外，针对扩散分解中的阈值确定问题，提出了一种基于拉依达准则的扩散阈值自动求解方法，实现了扩散阈值的自动求解。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。