Paper Notes 2023

2023-1月@2月@3月

English phrases

• (Journal of Molecular Liquids 363 (2022) 119873)

• These trends are exactly synchronous

  adj. 同步的；同时的

• To investigate this point 为了研究这一点

• In this scenario, 在这种情况下

• we conjecture that 我们推测

• It can explain why continuous hydrate growth is not easily observed in short-term molecular simulations

• This is similar to findings pertaining to the growth of tetrahydrofuran hydrate

  adj. 附属的；与……有关的

• To some extent,在一定程度上；在某种程度上

• To the best of our knowledge 据我们所知

• Methane hydrates are prevalent beneath ocean sediments 甲烷水合物普遍存在于海洋沉积物之下

• with a broad prospect in the studies of xxx,xxx,xxx.在xxx、xxx、xxx的研究中具有广阔的前景。

• This study deepens how solid surfaces affect the numerous hydrate-formation pathways. 这项研究深化了固体表面如何影响众多水合物形成途径。

• after which it fell，在那之后，

• at length 详细地

• vitreous body [解剖] 玻璃体

• To begin with 首先；本来

• Gas hydrates have attracted considerable interest since the discovery that much of the natural gas (methane) on Earth is tied up as crystalline hydrates in deep-sea sediments and in the permafrost

• clogging equipment 阻塞设备

• a potent greenhouse gas 强有力的温室气体

• In this respect在这方面

• sb postulated that 某人假设that

• account in（解释） an effective manner for polarization,

• account for（考虑） repulsion and dispersion interactions.

• extrapolating（外推） the system to infinite size in the direction of the temperature gradient.

• was imposed （施加）along the Z axis

• A procedure similar to that outlined above was followed to calculate the thermal conductivity 采用与上述相似的程序计算热导率

• As an additional ==corroboration== （n. 确证，证实；确证的事实） of the theoretical methodology employed in this work, the thermal conductivity of liquid water and of ice Ih were also calculated by the NEMD method and compared with experimental values.

• at a temperature of 300 K

• a rectangular parallelepiped（n. 平行六面体）simulation box

• it was not necessary to

• Test calculations carried out with a time step of 1 fs gave thermal conductivities nearly identical to（几乎完全相同） those obtained with the 2 fs time step, and the energy was well conserved in all simulations.

• It should be noted that it is difficult to obtain accurate measurements of the thermal conductivities of defect-free hydrates

• For all of these hydrates

• it is seen that the thermal conductivity can be expressed in terms of (依据) the product of（积） the density, specific heat, effective phonon velocity, and effective phonon mean free path.

  • product of the first three of these terms 前三项的积

• As mentioned above

• Most strikingly,

• identify the source of this discrepancy 确定这种差异的来源

• To further exploit the physical insights

• the state-of-the-art 最先进的研究进展 on the thermodynamics and formation kinetics of methane hydrate is presented.

• The remainder of this chapter is organized as follows. 本章其余部分的组织如下。

• ==Of particular concern is the fact that== gas hydrates are very sensitive to changes of external conditions such as temperature and pressure resulting from natural environmental changes and human activities.

• This agrees with the fact that,

• Such a definition of creep strain ==is analogous to== that of the engineering strain.

• ==To extract further== structural information about GB regions

• However, for the polycrystals in the relaxed state, the coordination numbers of water particles at GB regions ==are comparable to== those of grain interiors.

• water cages of methane hydrates ==are composed of== several membered rings.

• are all roughly equal to zero

• To elucidate in-depth the mechanical creep mechanisms behind the creep phenomena of polycrystalline methane hydrates,

• With regard to polycrystalline methane hydrates with large mean grain sizes,

• When subjected to low static stress

• Interestingly, the $4^15^{10}6^2$ cages can serve as an intermediate bridge in the structural transformation between structure I and H gas hydrates (J. Chem. Phys., 2015, 143, 011102)

• stability and lability

• It has been demonstrated that

• Memory preservation may differ from sample to sample 记忆保存可能因样本而异

• Given the experimental difficulties in attaining subtle details of molecular structures and motions during the decomposition and nucleation of gas hydrates;

• As demonstrated in Fig. 2b-2e; As illustrated in Fig. 6a,

• readily enter 很容易进入

• outermost layer 最外层

• fades away 逐渐消失

• methane molecules stemming from the destroyed cages flee from the decomposition solution completely.

• other parts are still intact 其他部分仍然完好无损

• Shortly afterward, 不久之后

• based on the timing when hydrate cages had just decomposed

水合物的记忆效应

• Generally, the memory effect is a phenomenon that gas hydrate reformation is faster in memory water, which refers to the water produced from the dissociation ofmethane hydrate, than in fresh water without a history of hydrate crystallization (Journal of Molecular Liquids 363 (2022) 119831)
• 也即，相比于本来就是水和甲烷的体系，甲烷水合物分解后生成的水和气体体系更易于重新生成甲烷水合物，即使只有很少的记忆水也能引发记忆效应；
• 一般认为，当温度远高于热力学相平衡边界时或者分解后保存的时间过长时，记忆效应才会消失；

水合物的玻璃体性质

• 一般晶体材料的热导率和温度是$T^{-1}$关系，而水合物一般随着温度升高，热导率小幅度升高，这与非晶态的类玻璃体相似。（J. Phys. Chem. B, Vol. 112, No. 33, 2008）

四体角序参数（four-body angular OP ）

• 

• Hydrate : F4 = 0.7

• Solid ice : F4 = -0.4

• Liquid water: F4 = -0.04

水合物数字岩心建模

水合物二次生成

• 水合物分解吸热和Joule-Thomson 效应（在气体通过节流阀的过程中，会产生压力突变，继而引起温度发生改变。这种现象被称为焦耳-汤姆逊效应）
• 由于水合物表面存在着大量的完全或半完全形成的笼型结构，因此有着较小的成核驱动力，导致水合物二次生成会自发避开先前不存在水合物的区域

屈服强度

• 屈服强度是金属材料发生屈服现象时的屈服极限，也就是抵抗微量塑性变形的应力。
• 于屈服强度的外力作用，将会使零件永久失效，无法恢复。

• 什么是屈服和屈服强度?

相关软件

• inspeXio：图形处理软件
• Avizo 2019.1

  文基于Avizo 软件，通过generate surface 命令将上文所构建的水合物饱和度38.5%的胶结型水合物沉积物数字岩心中水合物胶结物二值化图像堆栈、砂颗粒和孔吼空间合并后的二值化图像堆栈构建为STL（Stereo Lithography）网格模型后，然后通过smoothsurfacre 命令对其表面进行平滑，得到了质量较好的STL 网格模型
  

• OpenPIV
• 离散元数值模拟软件PFC3D 5.0

水合物稳定性

• 天然矿藏中，水合物的结构稳定压力通常是由周围的自由气层或孔隙水来维持。
• 具体工程应用上，热激法的实施方式主要有两种：（1）在预热井中直接注入热水或蒸汽，（2）井下电磁加热。
• 化学试剂（水合物抑制剂），如甲醇、盐水、乙醇、乙二醇、丙三醇等，可以改变水合物的相平衡条件，使水合物的稳定温度降低
• 相比于降压和热激法，抑制剂注入法起效较慢，但有着更低的前期能量投入。
• 二氧化碳水合物生成放热量高于甲烷水合物分解吸热量，保证了用二氧化碳分子置换甲烷水合物笼子中的甲烷分子的可行性，二氧化碳置换法可以同时实现开采甲烷气体、封存温室气体二氧化碳的目的，同时生成的二氧化碳水合物对于维持水合物沉积层的力学稳定性有着积极作用，防止由于水合物的相变导致地层失稳。
• 四氢呋喃tetrahydrofuran,ＴＨＦ,是一个杂环有机化合物，化学式为$C_4H_8O$，属于醚类，是呋喃的完全氢化产物，为无色透明液体，溶于水、乙醇、乙醚、丙酮、苯等，主要用作溶剂、化学合成中间体、分析试剂。
• 
• 四氢呋喃在2B类致癌物清单中
• 绝大部分天然水合物赋存在细沙或泥沙中，孔隙尺寸在十几纳米到几百纳米
• 小颗粒基质中的水合物生长则呈现了水合物团簇包裹并胶结固体基质的现象，并存在锋利的水合物－液界面
• 水合物的降压分解率先启动于水合物-气接触面，而在水合物-砂颗粒接触面处分解较慢。这主要是由于水合物与砂颗粒之间间隙较小，且砂颗粒自身较为密实，通过该方式实现传质难度较大，因此水合物降压分解选择了一个传质阻力较低的路径，即水合物-气接触面
• 由于水中的气体分子溶解度较低，因此这会增加水合物分解的传质阻力，降低水合物分解速率