Morphological evolution of three‐dimensional chemical dissolution front in fluid‐saturated porous media: a numerical simulation approach

This paper is concerned with the morphological evolution of three‐dimensional chemical dissolution fronts that occur in fluid‐saturated porous media. A fully coupled system between porosity, pore‐fluid flow and reactive chemical species transport is considered to describe this phenomenon. Using the newly presented concept of the generalized dimensionless pore fluid pressure‐gradient, which can be used to represent the interaction between solute advection, solute diffusion, chemical kinetics and the shape factor of the soluble mineral, a theoretical criterion has been established to assess the likelihood of instability at a chemical dissolution front in the reactive transport system. To simulate the chemical dissolution front evolution in a three‐dimensional fluid‐saturated porous medium, a numerical procedure combining both the finite difference method and the finite element method has been proposed. As the problem belongs to a complex system science problem, a small randomly generated perturbation of porosity is added to the initial porosity of a three‐dimensional homogeneous domain to trigger instability of a planar chemical dissolution front during its propagation within the fluid‐saturated porous medium. To test the correctness and accuracy of the proposed numerical procedure, a three‐dimensional benchmark problem has been constructed and the related analytical solution has been derived. This enables using the proposed numerical procedure for simulating the morphological evolution of a three‐dimensional chemical dissolution front from a stable, planar state into an unstable, fingering state. The related numerical results demonstrate that the proposed numerical procedure is useful for, and capable of, simulating the morphological instability of a three‐dimensional chemical dissolution front within a fluid‐saturated porous medium.     

战争期间日本妇女运动家市川房枝的政治转向

市川房枝是日本近代著名的妇女解放思想家,妇女运动的领导者,在战前和战后致力于日本妇女解放运动,但是曾因战争期间参加法西斯军国主义的战时体制,战后一度被解除公职,本文探讨的是1937年日本发动全面侵华战争时市川房枝的政治转向,即由争取妇女参政权运动转到为战时体制服务,在翼赞体制下号召和组织妇女支持侵略战争,并试图通过市川房枝为代表的妇女运动的转向,探求其转向的深层根源。     

从目录学史看《书画书录解题》在书画专科目录方面的成就

书画艺术文献是目前文献学研究领域中的薄弱环节。本文从古代艺术文献目录发生、发展角度,对出现在本世纪三十年代初中国目录学史上第一部书画专科目录学著作《书画书录解题》,从体例分类、著录思想等诸多方面加以比较分析,揭示了该书在艺术目录研究领域方面的创获与成就,并从一侧面反映了书画文献发展源流及目前所存在的问题。     

《庐阳客记》:一部失落已久的庐州志书

《庐阳客记》是合肥地区历代所存志书中,年代最为久远的,一直以来都认为已佚,并且未被重要方志目录著述所收录。作者在研究安徽方志史时,于《四库全书存目丛书》中发现此书。本文对此书作了简单介绍。此书有刻本,现存北京图书馆。     

詹天佑是否参与马江之战考

詹天佑是我国著名的铁路工程师,曾经主持修建了京张铁路.多年来,很多人围绕詹天佑有没有参加中法战争马江一战产生了很多分歧,至今仍莫衷一是.通过对比来自各方史料有关詹天佑有无参战的信息,得出在马江之战中,詹天佑早已不在扬武舰上,而是调往了福州船政局后学堂执教.但是,当马江战役打响时,他不畏强敌,前往现场与民众一起下水救人.之所以《字林西报》和《申报》报道詹天佑参战是属于误报,经过詹天佑后人的描述得到了更正.虽然詹天佑由于各种原因没有参战,但他下水救人的精神依然值得后人学习和敬仰.     

南唐二陵墓室彩画冷凝水治理研究

南唐二陵墓室在春夏之交、夏秋之交时产生大量冷凝水,严重危害墓室彩画安全。为此,在查阅文献资料和实地调研后,自2013年7月至8月对墓室内外环境温湿度进行了监测记录。结果表明:墓室内相对室外为持续低温(22℃)高湿(RH=100%)的状态,对彩画保存非常不利。随后结合室外温湿度测量记录数据,分析了冷凝水产生的原因。在此基础上,提出通过安装风幕机、除湿机对冷凝水进行治理的措施,并继续对治理效果进行跟踪测量记录,结果显示该措施能够有效降低墓室内相对湿度(RH=90%),对去除墓室内冷凝水进而保护墓室彩画有重要作用。     

宋代的桥与场务

桥梁控扼交通要道,宋以前或已于桥梁附近置有军镇以稽查行旅,后逐渐兼有征收商税、酒课之责。桥镇的转型、桥市的繁荣,为在近桥处征收商税、酒课提供了必要的条件。宋代征收商税、酒课的场务多有近桥而设者。设置在桥梁附近的场务及其税务官吏通过拦(河)锁邀截水陆两路以征税。从陆路通行的商品需在城门或税务交纳过税、门税等通过税,从水路通行的商品则有"船栰之征",多在近桥的河锁处缴纳。从汉唐的关市之征到宋代近桥而征的大量兴起,体现的是宋代商税征收网点的密集化与商税征收的普遍化。     

Migration and regional inequality: changing characteristics of China’s economic inequality

Scholars studying economic inequality in China have maintained that regional inequality and economic divergence across provinces have steadily increased over the past 30 years. New studies have shown that this trend is a statistical aberration; calculations show that instead of quickly and sharply rising, regional inequality has actually decreased, and most recently, remained stable. Our study suggests that China’s unique migratory regime is crucial to understanding these findings. We conduct a counterfactual simulation to demonstrate how migration and remittances have mitigated income inequality across provinces in order to show that without these processes, we would have seen more of a rise in interprovincial income inequality. We conclude by arguing that inequality in China is still increasing, but it is changing and becoming less place-based. As regional inequality decreases, there are signs that point to the increasing importance of interpersonal inequality.     

中国区域性旅游障碍研究探析

建设无障碍旅游区是中国区域旅游合作纵深发展的必然成果,其关键在于消除区域性的"旅游障碍"。然而当前国内对区域旅游障碍的研究却较少有。从研究分析来看,行之不畅不爽、信息不对称、服务疲软、管理的地方化倾向是区域性旅游障碍的主要表现形式。本文以为,区域性旅游障碍的形成和发展,是与地方政府行为质量、市场诚信发育程度、信息交流技术平台等因素密切相关的。消除区域性旅游障碍,必须切实提高地方政府组织区域旅游经济的行政作为质量,进一步规范市场竞争秩序、推进诚信建设,提高旅游企业素质和服务质量,完善区域间旅游交通的便捷性与信息交流的技术平台,促进中国区域旅游和谐发展。     

中国十大城市群综合发展水平的多层次因素分析及非均衡差异研究

中国十大城市群正在成为中国经济、科技、文化最发达的地区,成为了中国国民经济的十大支撑点,因此,研究中国十大城市群综合发展水平具有理论和实践上的重大意义。通过构建城市群综合发展水平评估指标体系,采用多层次因素分析与分类相结合的综合评估方法,对中国十大城市群综合发展水平进行了科学评估及比较,十大城市群综合发展水平呈现出四大集团的非均衡区域差异分布。同时分别提出了缩短领先型集团、挑战型集团、追赶型集团、后进型集团城市群综合发展水平非均衡差异的对策与建议。