查询词典 diffusion constant

Environment radon is mainly from rock and soil in geological environment, but the research is not connected with geological environment now. On the basis of physical field, the theoretical distribution model of radon in soil and exchange model of earth—air are set up by using Fick diffusion law and Dacy law, and then the research of environment radon is linked with geological environment. This paper described how the evry parameter of the theoretical model influence the radon concentration in air. The results of research indicat that molecule diffusion of radon is different from it's eddy form. Under the condition of surface radon source, the model experiment is used to study the transportation and distribution of radon in medium. The data of experiment show the relationship between radon and depth can be described by exponent. If the radioelement is well—distributtion, the concentration of radon in different depth or in different point at the same depth change with time, but the accumulated exhalation amount of radon at different point on the surface of model are close in relative long time. The author studied the exchange of radon between mediums and verified the theoretical models too.

环境氡主要来自岩石、土壤，而目前环境氡研究中与地质环境结合很少，为此作者以物理场为基础，运用气体运移的费克扩散定律和达西定律，建立起壤中氡浓度分布与大地—大气间氡交换理论模型，首次在理论上将环境氡与地质环境结合起来；论文中从理论上讨论了模型中各参数对空气中氡浓度的影响，发现空气中氡运移的分子扩散方式和湍流扩散方式存在明显差异；通过面状氡源条件下的氡运移模型实验，研究了介质中氡的运移与分布，实验数据表明氡浓度随深度的变化规律可用指数函数描述，在放射性元素分布均匀的条件下，介质中不同深度和同一深度不同点的氡浓度随时间而变，但介质表面不同点在较长时间内向空气中累计释放的氡的量是相近的；同时研究了不同介质间氡的交换，并验证了所建立的理论模型；运用理论模型预测青岛市城区壤中氡浓度、江西临川一住宅区空气中氡浓度及江西二个测区的区域空气中氡浓度分布，取得了较好的效果。

The self-diffusion coefficients of supercritical carbon dioxide and infinite dilute diffusion coefficients of methanol and ethanol in supercritical carbon dioxide were investigated by molecular dynamics simulation.

采用分子动力学模拟的方法对超临界二氧化碳的自扩散系数及甲醇和乙醇在超临界二氧化破中的无限稀释扩散系数进行了模拟计算。

Comparatively, Na^＋ has a wider diffusion range and higher self-diffusion coefficient than Mg^2＋.

在Na／Mg^-蒙脱石中，Na^＋和Mg^2＋的扩散方式不同，Na^＋的扩散范围相对更广，自扩散系数更大。

The one is how the long-range order of atoms can be restored when atomic diffusion takes place, and the other is how the theoretical expressions in their present form, more than one self-diffusion coefficient parameter, can be applied to experimental results directly.

一是如何正确理解原子的热扩散运动与合金中原子有序排列之间的矛盾；二是能否将扩散系数以外的其它理论参量与原子跳跃迁移的相关实验测量联系起来。

The self-diffusion coefficients and diffusion pathways of hexane, as well as the mobility of the frameworks were investigated, as a function of both temperature and loading.

本文重点研究了温度和分子数对己烷自扩散系数、扩散机理，以及骨架柔性的影响。

At the temperature range of 800～850℃, the deformation activation energy was very close to self-diffusion activation energy of grain boundary, which shows the main deformation mechanism is grain boundary sliding controlled by grain boundary diffusion.

在850℃变形激活能与晶界自扩散激活能十分相近，表明晶界扩散控制的晶界滑动是超塑性变形的主要机制。

Self-diffusion coefficient ; Infinite dilute diffusion coefficient ; Supercritical fluid ; Molecular dynamics ; Molecular simulation

自扩散系数；无限稀释扩散系数；超临界流体；分子动力学；分子模拟

With the increase of pressure, the hydrogen bond strength between water molecules increases, while self-diffusion coefficient decreases. With the increase of temperature, the hydrogen bond strength between water molecules decreases, while self-diffusion coefficient increases.

模拟结果表明，随着压强的增大，水分子间的氢键作用增强，扩散系数减小；随着温度的升高，水分子间的氢键作用减弱，有序程度下降，扩散系数增大。

The results show that the silicide coating is formed by reactive diffusion and the silicification process obeys parabolic relation. The coating is composed of composite structures including MoSi2 outer layer, two-phase transient zone with major NbSi2 and minor Nb5Si3, and Nb5Si3 diffusion inner layer. The coating possesses good high-temperature oxidation resistance and spalling resistance.

研究结果表明：包渗法制备硅化物涂层是通过反应扩散形成的，硅化过程服从抛物线规律；该涂层为复合结构：MoSi2相为主体层；以NbSi2相为主、并含少量Nb5Si3相的两相为过渡区；Nb5Si3相为扩散层。

It establishes the uniform, singular and two kinds of normal distributions models of diffusion layer statistical distribution, the result shows that the more singular the statistical distribution of the cathode gas diffusion layer porosity is, the better the cell performance is, and the more uniform, the worse the cell performance is.

最后，从热力学的角度分析了燃料电池过程的能量转化形式，反应的焓变主要转变成电能和热能两种能量形式；归纳了燃料电池电化学的一些基本理论模型及简单的推导过程；描述了燃料电池效率的一些不同的定义以及对采用热电联供的方式提高燃料电池能量利用效率的分析。

The changes of the HAF after liver injury may be related to the volume of blood loss, the intraabdominal pressure and the pneumoperitoneum duration.

肝撞击伤伴失血后肝动脉血流量的变化与失血量、气腹压力以及气腹持续时间等有密切联系。

Reneging on our commitments to the world's poor cannot be an austerity measure, she said.

放弃我们给世界上的穷国的承诺不能成为一种紧缩措施。