煤矿开采覆岩移动规律的相似模拟研究

以淮南某煤矿1811（1）工作面为研究对象,利用相似材料模拟试验,分析受采动影响的上覆岩层的移动变形规律。结果表明,受采动影响的上覆岩层依次发育成冒落带、裂隙带、弯曲带。通过对下沉、倾斜、曲率、水平移动、水平变形五个参数的动态曲线分析,总结上覆岩层的力学状态。     

东海黑潮周边中尺度涡的分布、运动规律以及生成机制

为了探究东海黑潮周边涡旋分布、形成机理及运动规律,基于法国国家空间研究中心(CNES)卫星海洋学存档数据中心(AVISO)的中尺度涡旋数据集展开了研究。首先,统计了近27年东海黑潮周边的涡旋分布,发现在黑潮弯曲海域产生了650个涡旋,在黑潮中段海域产生了271个涡旋,其中直径100~150 km之间的涡旋数量最多,涡旋振幅主要集中在2~6 cm。其次,分析了东海黑潮的运动路径和涡运动过程,结果表明,黑潮气旋式弯曲海域内侧易产生气旋涡,且移动路径较长,如台湾东北海域黑潮流轴气旋式弯曲处产生的涡旋,其平均位移达到了87.6 km;当反气旋式弯曲海域内侧产生反气旋涡时,涡旋往往做徘徊运动。黑潮中段海域的涡旋呈现出气旋涡在黑潮主轴西侧、反气旋涡在黑潮主轴东侧的极性对称分布特征,两类涡都沿黑潮主轴向东北方向移动。最后,结合再分析的流场、海面高度数据,讨论了涡旋运动规律和生成机制。黑潮弯曲处涡旋的生成与黑潮流体边界层分离有关,奄美大岛南部到冲绳岛西侧的黑潮逆流对黑潮中段海域涡的极性对称分布起到了关键作用,涡旋在运动过程中通常经历生长、成熟和衰变三个阶段。     

水产品合法性标签制度的法律属性及其立法完善

为促进我国渔业资源和水产品贸易的可持续发展,文章结合国际和国内的相关实践情况,分析我国水产品合法性标签制度的立法现状和存在的不足,尝试解答其中的关键问题即水产品合法性标签制度的法律属性,并就相关立法的完善提出建议。研究结果表明:水产品合法性标签制度是国际社会破解非法、不报告和不管制捕捞难题的重要制度,我国已开展相关实践并推动立法进程;目前我国水产品合法性标签制度的立法现状主要包括发布相关规范性文件和修订渔业法律,但该项制度在法律依据等方面仍存在不足;水产品合法性标签在法律上应被认定为强制标志,该项制度应属于强制性行政确认,且可适用于水产品国内贸易;在我国渔业法律的修订过程中,应通过健全实施程序和明确法律后果,进一步完善水产品合法性标签制度。     

Locating the Melody of the Drives

Psychoanalysis has profoundly influenced those social theories that inform qualitative methodology in human geography. Yet many geographers are skeptical about the value and viability of psychoanalytic methodology because of its alleged reductionist causal explanations and relativistic interpretations of data. Drawing on the work of Slavoj ?i?ek, which affirms Jacques Lacan's undermining of the dualism of causality versus sense, this article illustrates the potential value of Lacanian psychoanalysis as a qualitative methodology in geography. Using a methodological case study from my research on Jamaican tourism, I illustrate how we can locate a Lacanian understanding of the drives in the interactions between tourists and hotel workers. In so doing, the article provides new insights into the enduring allures of tourism's commodity-form by focusing on how the object petit a—a chimerical object that incites desire and an unattainable object that the drives encircle—takes place in customer service and entertainment activities.     

Instrumental method for reducing error in compression-derived measurements of rainfall interception for individual trees

Abstract

This technical note presents an instrumental method for the precise and timely installation of mechanical displacement sensors to investigate stem compression and relaxation associated with whole-tree rainwater loading and evaporation, respectively. We developed this procedure in response to the conclusions of Friesen et al. (2008 Friesen, J. 2008. Tree rainfall interception measured by stem compression. Water Resources Research, 44 doi:doi:10.1029/2008 WR007074. [Google Scholar]), which called for the development of a precision mounting method for strain sensors on inherently-irregular trunk cross-sections so that rainfall interception, storage and evaporation may be distinguished from other strain-related phenomena. To supply precise sensor installation locations, high-resolution trunk profiles are generated using the LaserBark^TM automated tree measurement system. These scans are utilized to approximate the location of neutral bending axes. A routine then instructs a mobile rangefinder along the cross-section to optically indicate exact positioning for strain sensors over the bending axes. As imprecise sensor placement linearly increases error and diminishes signal-to-noise ratio, this automated installation routine is designed to remove significant distortions created by wind throw, off-centre loading within unevenly-distributed canopies, and human error that can lead to erroneous measurements of rainfall interception.

Citation Van Stan, J. T. II, Jarvis, M. T., Levia, D. F. Jr & Friesen, J. (2011) Instrumental method for reducing error in compressionderived measurements of rainfall interception for individual trees. Hydrol. Sci. J. 56(6), 1061–1066.     

Street hierarchies: a minority of streets account for a majority of traffic flow

Urban streets are hierarchically organized in the sense that a majority of streets are trivial, while a minority of streets is vital. This hierarchy can be simply, but elegantly, characterized by the 80/20 principle, i.e. 80% of streets are less connected (below the average), while 20% of streets are well connected (above the average); out of the 20%, there is 1% of streets that are extremely well connected. This paper, using a European city as an example, examined, at a much more detailed level, such street hierarchies from the perspective of geometric and topological properties. Based on an empirical study, we further proved a previous conjecture that a minority of streets accounts for a majority of traffic flow; more accurately, the 20% of top streets accommodate 80% of traffic flow (20/80), and the 1% of top streets account for more than 20% of traffic flow (1/20). Our study provides new evidence as to how a city is (self‐)organized, contributing to the understanding of cities and their evolution using increasingly available mobility geographic information.     

A prefetching model based on access popularity for geospatial data in a cluster-based caching system

Geospatial tile popularity reflects the general characteristics of user preferences in tile access. However, tile access has both long-term popularity features (characterized as stable) and short-term popularity features (characterized as explosive). Specific features of tile popularity are an important theoretical basis for improving the accuracy of caching and prefetching. This article considers both long-term and short-term popularity features for tile access and presents a Markov prefetching model in a cluster-based caching system based on a Zipf distribution. First, it describes the navigation path and the transition probability path for tile access based on the global features of tile access to find a way to estimate the transition tile access probabilities based on the access pattern, which satisfies Zipf's law. Then, based on temporal and spatial local changes in tile access patterns, the basic Markov model is used to prefetch tiles with the highest probability in the follow-up state for current hot tiles and these tiles are labeled as the set of prefetched objects. Finally, based on the access probability for prefetched tiles, they are evenly distributed in a cluster-based caching system. This method takes into account both global and local space–time changes in tile access patterns. This method not only makes the set of cached objects relatively stable but also adapts to changes in access distribution. Experimental results reveal that this method has a higher prefetch hit rate and a shorter average response time for tile requests and thus can improve the efficiency and stability of cluster-based caching systems.     

Legal Geographies—Governing Through Law: Rightsbased Conflicts and Property Development in Shanghai

This article examines recent legislation on the mandatory practice of government adjudication and its impacts on community residents' legal challenges to chaiqian (demolition and relocation) in Shanghai. In recent years, rights-based grievances over community displacement have become a major source of social conflict in urban China. The new legislation represents the Chinese state's efforts to establish a law-based model through which to govern an increasingly rights-conscious society. It is argued that the mandatory practice of government adjudication has smoothed out the conflict-laden property development process by establishing a legalized channel for affected residents to express their claims of rights and interests. Yet, at the same time, legislative practice has also reinforced the government's control in defining social interests to which residents' individual rights are subordinate.     

CARBONATE EROSION RATES IN SOUTHWESTERN WISCONSIN

Between 1977 and 1979 three sets of erosional weight loss tablets were em-placed in the karst of southwestern Wisconsin to measure both potential and actual rates of carbonate erosion. Tablets of Jamaican White Limestone, which has been used in many other karst areas, were used to gauge relative erosion potential while tablets of the local bedrock, Prairie du Chien dolomite, were used to assess absolute rates. Tablets of Yugoslavian limestone were emplaced as part of a world-wide study of comparative rates. Tablets were recovered in 1983 and 1984. Although potential erosion rates are similar to those in other carbonate areas, the sluggish dissolution of the indigenous dolomite retards karst development. Soil cover increases erosion rates and rates at a given depth are consistent over sites of up to 10 m². The highest erosion rates were recorded by the Yugoslavian tablets but betweensite variations caution that results based on a single site may be unrepresentative. Over 37% of all tablets were affected by mechanical weathering processes, probably freeze-thaw action.