Phase‐field modeling of epitaxial growth of polycrystalline quartz veins in hydrothermal experiments

Mineral precipitation in an open fracture plays a crucial role in the evolution of fracture permeability in rocks, and the microstructural development and precipitation rates are closely linked to fluid composition, the kind of host rock as well as temperature and pressure. In this study, we develop a continuum thermodynamic model to understand polycrystalline growth of quartz aggregates from the rock surface. The adapted multiphase‐field model takes into consideration both the absolute growth rate as a function of the driving force of the reaction (free energy differences between solid and liquid phases), and the equilibrium crystal shape (Wulff shape). In addition, we realize the anisotropic shape of the quartz crystal by introducing relative growth rates of the facets. The missing parameters of the model, including surface energy and relative growth rates, are determined by detailed analysis of the crystal shapes and crystallographic orientation of polycrystalline quartz aggregates in veins synthesized in previous hydrothermal experiments. The growth simulations were carried out for a single crystal and for grain aggregates from a rock surface. The single crystal simulation reveals the importance of crystal facetting on the growth rate; for example, growth velocity in the c‐axis direction drops by a factor of ~9 when the faceting is complete. The textures produced by the polycrystal simulations are similar to those observed in the hydrothermal experiments, including the number of surviving grains and crystallographic preferred orientations as a function of the distance from the rock wall. Our model and the methods to define its parameters provide a basis for further investigation of fracture sealing under varying conditions.     

邓小平绿色发展思想的历史考察

邓小平在人与自然关系的主体方面,主张控制人口,主要涉及绿色发展的人口与资源协调发展观;在人与自然关系的客体要素方面,倡行植树造林,内含了绿色发展的生态安全观、群众主体观和持续绿化观;在协调人与自然关系的支撑条件方面,强调科教对经济建设和环境建设的先导作用,突出立法建制对环保事业发展的保障作用,蕴含有绿色发展的科技观、教育观和法制观。总结和研究邓小平绿色发展思想,对于深入把握当代中国马克思主义绿色发展观的历史与理论逻辑,贯彻落实党的十八大以来关于生态文明建设的新认识、新设计、新规范,实现美丽中国梦具有重要意义。     

西安钟楼建筑彩画样品材质分析

为了研究西安钟楼建筑彩画的制作材料,本工作采用超景深显微镜、X射线荧光分析仪、X射线衍射仪和气相色谱质谱联用仪对西安钟楼建筑彩画样品进行了分析。结果表明,该彩画样品地仗层采用单披灰制作工艺,两层红色颜料都是土红,绿色颜料使用了近代人工合成颜料——巴黎绿,胶粘剂含有动物胶。该研究成果对西安钟楼彩画后期修复保护材料和工艺的选择具有指导意义。     

湖南省区域趋同分析

根据区域趋同基本理论,采用新古典方法分析了湖南省区域趋同状况.结果表明,自我国实施社会主义市场经济体制以来,湖南省区域经济增长总体表现为条件趋同,趋同速度约为每年1.93%.受地理区位的影响,湖南省内部区域差异较大,国家发展政策对湖南省区域趋同的影响相当显著,例如,湘西自治州纳入西部大开发增强了湖南省区域增长的收敛性.而产业结构和投资状况对于区域经济增长的作用不强.在此基础上,提出几点促进湖南省区域趋同的对策.     

引进外资对中国工业化和经济结构变化的影响

本文从中国经济增长两个阶段的不同特点入手,分析了90年代中期以后中国大量引进外资的深层次原因。采用制造业增加值占GDP的比重作为衡量中国工业化进展程度的指标对整个90年代中国工业化的进程进行了实证分析,结果发现,中国的工业化从90年代中期以来实际上长期处于低速徘徊的阶段。大量引进外资导致中国工业化过程中存在两个明显的"替代效应",一是"外资替代效应",二是"弱质替代强质"现象。两个"替代效应"对中国工业化和经济结构变化的影响是极为深刻的。     

Greening America's Skylines: The Diffusion of Low-Salience Policies

The diffusion literature is replete with examples of highly salient policies spreading across subnational governments. However, low-salience policies that do not benefit from a groundswell of public opinion also spread across jurisdictions in patterns that appear similar to those of other, more well-known policy ideas. This research is an investigation of the mechanisms that propagate low-salience policies. I analyze the adoption of the U.S. Green Building Council's (USGBC) Leadership in Energy Efficient Design standard across 119 U.S. cities from 2000 to 2008. The investigation indicates that a knowledge broker, in this case the USGBC, occupies critical roles in linking a low-salience policy to a broader set of widely held societal values, developing a common policy vocabulary, providing a base policy that jurisdictions may freely adapt, and creating a diffusion infrastructure by acting as a communication hub for existing and interested jurisdictions to discuss innovations and progress.     

“十二五”时期青海省加快发展绿色经济问题研究

面对全球绿色发展浪潮和新一轮经济转型的机遇和挑战,青海省如何在制定和落实＂十二五＂规划过程中加快推动绿色经济发展,在更高层次上实现经济、社会与生态可持续发展,成为一个亟待研究和解决的重大现实问题。基于此,本文探讨了＂十二五＂时期青海省加快发展绿色经济的新思路、新路径,以期为政府决策提供相关的参考依据。     

邮轮旅游者未来价值评估与潜类分析模型——以大陆、香港和台湾为例

自20 世纪80 年代以来,现代邮轮旅游作为一种休闲度假方式,已经成为欧美国家中产阶级出游的重要选择之一。深入了解中国邮轮旅游者的特点并进行市场细分,有助于推动中国邮轮旅游市场开发。本研究根据顾客终身价值理论,测算了邮轮旅游者的未来价值,并通过探索性因子分析和验证性因子分析研究了邮轮旅游者的消费偏好,建立了邮轮旅游者未来价值评估模型。基于中国大陆、香港和台湾邮轮旅游者的相关数据,通过AMOS21.0 对邮轮旅游者未来价值模型进行了检验,发现了对邮轮旅游者未来价值有显著影响的因素;通过R13.0 软件进一步对显著影响邮轮旅游者未来价值的因素进行了潜类分析,识别出了未来价值较高的邮轮旅游市场,进而为有效地市场开发提供依据。     

西安城市居民绿色出行的群体参照影响与自我价值判断

选择本土城市居民为研究对象,以参照群体影响为外界变量,以自我感知价值为内部判断变量,将二者关联绿色出行意愿,意欲明晰是外部群体影响还是自我价值判断最终主导了人们的绿色出行选择。研究结果显示：参照群体的两类影响（信息性影响与规范性影响）对居民绿色出行意愿有显著正向影响;功能性感知价值与社会性感知价值对居民绿色出行意愿有显著正向影响,而情感性感知价值对居民绿色出行意愿影响不显著;中介效应结果表明,绿色出行感知价值在参照群体影响与居民绿色出行意愿之间存在部分或完全中介过程。     

Urban growth drivers in a Europe of sticky people and implicit boundaries

We investigate urban GDP per capita growth across the EU12 usingdata for functionally defined cities—rather than administrativeregions. We test hypotheses on the role of human capital, EUintegration and fragmentation of urban government and explorespatial dependence and mechanisms of spatial interaction. Resultsare acceptable on standard econometric tests without measuresof spatial interaction but there is spatial dependence. If variablesreflecting spatial adjustment are included, they are statisticallysignificant and eliminate spatial dependence. Not only do theresults now provide consistent estimates of parameters, butthey also support relevant theoretical insights and show nationalborders are still significant barriers to economic adjustment.People in Europe are sticky so it is unreasonable to assumespatial disparities will disappear. Our findings also implythat cities in Europe form national rather than a single continentalsystem.