Fluid effect on hydraulic fracture propagation behavior: a comparison between water and supercritical CO2‐like fluid

The initiation of hydraulic fractures during fluid injection in deep formations can be either engineered or induced unintentionally. Upon injection of CO₂, the pore fluids in deep formations can be changed from oil/saline water to CO₂ or CO₂ dominated. The type of fluid is important not only because the fluid must fracture the rock, but also because rocks saturated with different pore fluids behave differently. We investigated the influence of fluid properties on fracture propagation behavior by using the cohesive zone model in conjunction with a poroelasticity model. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Low viscosity fluids with properties of supercritical CO₂ will create relatively thin and much shorter fractures in comparison with fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation: the time at which a crack ceases opening and the later time point at which a crack ceases propagating. These times are very different for different fluids. Both fluid compressibility and viscosity influence fracture propagation, with viscosity being the more important property. Viscosity can greatly affect hydraulic conductivity and the leak‐off coefficient. This analysis assumes the in‐situ pore fluid and injected fluid are the same and the pore space is 100% saturated by that fluid at the beginning of the simulation.     

晚清"古学复兴":中国旧学纳入近代新知体系之尝试

章太炎、刘师培等人在清末“保存国粹”、“复兴古学”的过程中,开始对中国古代学术进行初步整理,肇始了对中国学术遗产进行发掘、梳理、研究和整合之工作。以西方新知、新理、新法整理中国传统旧籍,发明中国旧学之新义,是晚清学术演进之必然趋势。以新知阐释旧学,以中学比附西学,以近代学科体系界定中国旧学,是晚清学者整理中国旧学之基本思路。正是在对中国传统学术不断进行整理和整合的过程中,中国传统学术开始转变其固有形态,逐步融入近代西学新知体系之中。     

The Archaeology of Regions: From Discrete Analytical Toolkit to Ubiquitous Spatial Perspective

In the 1970s and 1980s, regional analysis was an influential part of archaeological research, providing a discrete set of geographical tools inspired by a processual epistemological and interpretive perspective. With the advent of new technologies, new methods, and new paradigms, archaeological research on regional space has undergone significant changes. This article reviews the state of regional archaeology, beginning with a consideration of its history and a discussion of the fundamental issues facing regional investigations before focusing on developments over the last several years. On one hand, the diversification of archaeological theory has created new paradigms for thinking about human relationships with one another and with the physical environment across regional space; in this regard, historical ecology, landscape archaeology, and evolutionary theory have been particularly influential in recent years. This has led to a corresponding diversification of the traditional methods of regional analysis. Most notably, the advent of powerful digital technologies has introduced new tools, especially those from the geographic information sciences, that build on the quantitative methods of past approaches. The investigation of regional data is no longer based on a discrete toolkit of simple mathematical and graphical procedures for representing spatial relationships. Instead, regional archaeology has matured into a diversity of multiscalar spatial and geostatistical techniques that inform many areas of archaeological inquiry.     

英语教学史百年回顾——改革运动前后语法翻译法与自然法的变迁

改革运动(Reform Movement)是指1882～1904期间主要在欧洲掀起的外语教学改革。回顾改革运动前后语法翻译法与自然法的变迁,时间跨度在一百年以上,为现在语言教育研究人员提供一些外语教育研究的理论基础,希望语言教学和研究者可以从中找出更多的教学发现从而提高现代语言教学质量。     

南宋川陕战区兵力部署的失衡与吴曦之变

南宋在川陕战区兵力部署中,基于战略防御和节制武将的考虑,形成兴州、金州、兴元府三大屯驻重心。在具体兵力分布上,由于吴氏武将集团的影响,兴州驻军的数量与实力最为强大,呈现出严重的失衡状态。兴州驻军力量过于强大是吴曦据兴州叛变的关键因素。吴曦叛变平定后,南宋对兴州军事力量予以分化,又导致兵力分散和不利于边疆防御的弊端,体现出南宋削弱地方军事力量与加强边疆防御的两难困境。川陕战区兵力部署的演变,蕴涵着南宋加强中央集权的真实内容。     

How Was Edmond Halley’s Map of Magnetic Declination (1701) Constructed?

Edmond Halley made two scientific voyages in the Atlantic Ocean as captain of the HMS Paramore between 1698 and 1700. Following these voyages he published the first map showing lines of equal magnetic declination in 1701. Halley did not reveal how he constructed the map, however, and it remains unknown. In this study, a construction procedure is hypothesized that uses mathematical tools that were available in his day, namely arithmetical averages and Isaac Newton’s method of divided difference for fitting a polynomial curve to data. To enable his map construction, a method is suggested whereby Halley could have created new data to augment the situations where insufficient data were collected.     

大预应力锚索在将军崖岩画保护中的选择与应用

文章介绍了大预应力锚索在将军崖岩画保护中的选择与应用,强调了科学技术在文物保护中突出作用。     

Overpressure in the Malay Basin and prediction methods

Predrill overpressure prediction is important for well planning and migration modeling for prospect evaluation. The Eaton (Journal of Petroleum Technology, 24 , 1972, 929) and Bowers (SPE Drilling & Completion, 10 , 1995, 89) methods are used worldwide for postdrill overpressure prediction using sonic log and predrill overpressure prediction using seismic interval velocity. In this research, these two methods were used for overpressure prediction using 3D anisotropic prestack depth‐migrated seismic interval velocity in a field of the Malay Basin. In the shallow overpressured zone, where the mechanism of overpressure is undercompaction, the onset of overpressure was predicted reasonably well using the Eaton and Bowers methods with their standard parameters (i.e., Eaton exponent 3 and Bowers loading curve) for seismic velocity. However, in the deep overpressured zone, where fluid expansion is the cause of overpressure generation, these methods underpredicted the high overpressure. In the deep overpressured zone, the overpressures were better predicted by applying a correction to the Eaton method. On the other hand, the Bowers unloading parameters for the fluid expansion mechanisms did not show any significant effect on overpressure prediction. Hence, in the study area, the Bowers method is not effective for 3D overpressure prediction using seismic velocity, whereas the Eaton method is more robust and can be used for 3D overpressure prediction from seismic velocity.     

东北地区劳动力国际流动的特点、影响因素与对策研究

本文分析了东北地区劳动力国际流动数量和营业额在全国的地位、去往国别、从事的行业等特点,论述和分析了影响东北地区劳动力国际流动的有利和不利因素。针对存在的问题,提出了发展东北地区劳动力国际流动的基本对策。     

旅游产业部门结构合理性的SSM分析-以陕西省为例

为了寻求省域旅游产业发展的合理部门结构,利用偏离-份额分析法,以旅游统计年鉴提供的数据为基础,对陕西省旅游创汇部门的产业结构进行实证分析。研究表明陕西省各旅游创汇产业部门中,原有基础好,竞争力较强、具有部门优势的增长部门包括商品销售、邮电通讯和市政交通等部门;原有基础差但发展快,竞争力较好,具备一定部门优势的增长部门包括住宿、餐饮业等;基础较好,但竞争力较差的部门则包括长途交通运输业、观光游览、娱乐业等。论文针对各部门实际发展状况分别进行了分析,指出各自发展方向和策略。最后评价了偏离-份额分析法在旅游创汇部门产业结构分析中的应用效果,认为该方法具有较强的综合性和动态性,能够有效揭示旅游创汇各部门产业结构变化的原因和发展机制,是确定未来旅游业创汇部门发展主导方向的有效方法之一。