Multiphase flow simulation through porous media with explicitly resolved fractures

Accurate simulation of multiphase flow in fractured porous media remains a challenge. An important problem is the representation of the discontinuous or near discontinuous behaviour of saturation in real geological formations. In the classical continuum approach, a refined mesh is required at the interface between fracture and porous media to capture the steep gradients in saturation and saturation‐dependent transport properties. This dramatically increases the computational load when large numbers of fractures are present in the numerical model. A discontinuous finite element method is reported here to model flow in fractured porous media. The governing multiphase porous media flow equations are solved in the adaptive mesh computational fluid dynamics code IC‐FERST on unstructured meshes. The method is based on a mixed control volume – discontinuous finite element formulation. This is combined with the P_N+1DG‐P_NDG element pair, which has discontinuous (order N+1) representation for velocity and discontinuous (order N) representation for pressure. A number of test cases are used to evaluate the method's ability to model fracture flow. The first is used to verify the performance of the element pair on structured and unstructured meshes of different resolution. Multiphase flow is then modelled in a range of idealised and simple fracture patterns. Solutions with sharp saturation fronts and computational economy in terms of mesh size are illustrated.     

Chemical and Microscopic Study of Masonry Mortar in Ancient Pagodas in East China

Ancient mortars played a crucial role in the construction of historical architectures due to their physical and chemical compatibility with traditional building materials such as stones and bricks. Therefore, the analysis and optimization of the ancient mortar formula are significant in the restoration and preservation of historical sites. In this work, 20 mortar samples selected from five ancient stone pagodas in Zhejiang Province, China, were analyzed. The results showed that mud, lime-soil mortar, lime-sand mortar, and lime-gypsum mortar were used as binders in these pagodas. The Ca(OH)₂/aggregate ratio ranging from 0.3 to 2.7 was usually used to prepare lime mortar. Protein and polysaccharide were also found in some samples.     

“罗马和平”时期石碑的保护修复

罗马帝国初期的200年(公元前27年~公元2世纪)是罗马的鼎盛时期,开创了经济、文化、军事、艺术前所未有的高峰,被称为"罗马和平"时期。本文保护修复的几件"罗马和平"时期的石碑原本收藏在意大利罗维纳市的Lapidario博物馆,后委托意大利博洛尼亚KRITERION文物修复公司进行保护修复,进行了清洗、补全、封护等保护修复工作。     

关于利用历史文献信息进行环境演变研究的几点看法

针对如何更好地利用我国丰富的历史文献记录,开展历史时期环境演变研究,本文提出四点看法:从地球系统科学与全球变化研究的前沿中寻找研究的主题,在诸多不确定中寻找确定性答案,构建历史文献信息共享的环境演变研究平台,培养文理兼备的复合型人才。     

全球化语境下的民族节日走向——以当代中国节日为例

21世纪是全球化加速的时代,信息技术与快速的交通方式将广袤的世界变成了一个共处的地球村落。原本天地悬隔、各自分离、独立自足的族群在世界经济一体化的过程中迅速成为声息相通的"邻里街坊"。原本各自独立成长过程中形成的历史文化经验,使族群拥有各自的文化传统,这些有着独立文化传统的族群在全球化过程中猝然相遇,彼此之间的冲突与不适不可避免,因此互相的磨合、适应需要一个较长的时间过程。     

试论唐朝的“中国”与“天下”

唐代“中国”一词大体用于追述前代和议论当朝。唐代“中国”有地域、文化、民族及政权的含义,可以用来指代朝廷直接统治区域、中原为核心的地区或内地,是“天下”的核心或重要组成部分。唐朝“天下”一词有广义、狭义之分。狭义的“天下”指唐朝实际统治的范围即唐朝统一多民族的国家,这是唐朝“天下”的主要含义。此“天下”与“军国”、“邦国”基本同义,但各有侧重。“军国”最郑重,一般用于中央最高决策机构首脑的职掌范围;“邦国”更普通,主要用于官府和中央事务的层面;“天下”更广泛,一般用于中央和地方、官吏和百姓两方面事务的层面。广义的“天下”则指以“中国”为核心,以唐朝统一多民族国家(狭义“天下”)为政治实体,包容其他国家的世界体系和政治秩序。     

土族纳顿节仪式展演中的表演艺术

纳顿节是在青海省民和回族土族自治县三川地区以各土族村庄为单位举行的大规模的民族传统节日,每年从农历七月十二开始,至农历九月十五结束,其主旨是通过祭祀二郎神和本村保护神以祈求风调雨顺、五谷丰登,内容包括迎神、供献、许愿、还愿、会手、     

陕西蓝田水陆庵彩绘泥塑颜料分析研究

水陆庵位于陕西蓝田王顺山下,庵内现存三百余平方米精美绝伦的明代彩绘泥塑,是我国泥塑保存最多、最完整的明代彩绘泥塑群之一。为明确水陆庵彩绘泥塑的颜料使用情况,采用光学显微镜、X射线衍射仪、显微红外光谱仪、扫描电镜-能谱仪和显微拉曼光谱仪对颜料样品进行科学分析。结果表明,除中隔壁背面重妆区域的蓝色颜料主要成分是普鲁士蓝之外,水陆庵彩塑使用的颜料大多为矿物颜料,包括铅丹、朱砂、铁红、氯铜矿、雌黄和云母等。研究结果将为水陆庵后续保护修复提供科学依据,并为丰富关中地区明代彩绘泥塑颜料类型补充科学信息。     

建国初期"联苏抗美"国防战略思路论析

建国初期"联苏抗美"的国防战略是"一边倒"外交战略的延伸,但不能将两者混淆。"一边倒"外交战略着眼点在于社会制度的一致和意识形态的价值取向,"联苏抗美"的国防战略着眼于国家安全和国防巩固,它的提出既有历史经验的因素,更取决于新中国国家安全环境;它经受了历史的检验,证明是一个符合当时新中国国家安全利益的正确的决策,应给予充分的肯定。     

六朝古卷:"唐写本《世说新书》残卷"揭秘

十九世纪末在日本发现的"唐写本《世说新书》残卷"(以下简称"残卷"),是与《世说新语》原本最为接近的古抄本,其学术价值和艺术价值举世公认."残卷"向称唐人写本,近百年来,学术界众口一词,绝无异议.然而笔者在研读的过程中,从避讳学的角度对"残卷"加以审视,发现它本来是一部更为珍贵的六朝古卷,具体言之,乃是梁代之写本.而为人们所深信不疑的"唐写本"之成说,殆不能成立.兹考论于下,以发千古溟没之幽光.