羌塘盆地晚三叠世构造属性与层序地层格架下聚煤特征

依据近年来最新资料,通过对羌塘盆地南、北边界构造带构造属性、地球动力学机制及构造演化历程的讨论,剖析了羌塘盆地晚三叠世构造属性与盆地演化历程;在对盆地内部不同位置上三叠统岩性、岩相研究的基础上,通过不同古地理背景下层序界面与体系域界面的识别,建立了羌塘盆地晚三叠世层序地层格架,讨论了煤层在层序格架下的位置、聚煤特征及空间分布规律。研究表明,羌塘盆地晚三叠世为一复杂叠合盆地,经历了晚三叠世早、中期被动陆缘盆地,晚三叠世晚期羌北前陆盆地和羌南被动陆缘裂陷-坳陷盆地等不同的盆地演化历程;上三叠统构成一个完整的构造层序和两个三级层序,煤层位于高位体系域中上部,主要受控于高频率低级次海平面变化。具含煤岩系厚度大,煤层层数多,单层厚度小的特征;三角洲平原地带有利于煤层发育,三角洲沉积体系沿分割羌南、羌北盆地的中央隆起带发育,进一步指出该带是羌塘盆地内今后重要的找煤方向,并得到新发现的赛包玛煤点验证。     

箕状断陷湖盆不同构造区带成岩作用特征及差异性研究:以东营凹陷沙河街组为例

东营凹陷在沙河街组沉积期为北陡南缓的箕状断陷湖盆,凹陷内可进一步细分为陡坡带、缓坡带、洼陷带及中央背斜带。在沙河街组成岩演化过程中发育了多种类型的成岩作用,主要包括压实作用、压溶作用、溶解作用、胶结作用等。不同构造区带成岩作用具有明显的差异性,具体表现为:压实作用总体表现为早期压实影响较大,后期较小,但不同构造区带差异明显;胶结作用在不同构造区带碳酸盐胶结胶物含量不同。不同粘土矿物在不同构造区带含量及转化深度不同;溶蚀作用在不同构造区带发育深度不同,从而导致次生孔隙带发育深度均明显不同。不同构造区带成岩作用的差异性导致不同构造区带成岩相带类型、特征不同。详细研究这种差异性对于寻找岩性油气藏具有重要的理论价值和实际意义。     

综合物探在博格达山前古牧地复杂构造中的应用

准噶尔盆地南缘古牧地地区具有丰富的油气勘探潜力,但由于中深层地震成像存在盲区,长期以来对古牧地构造特征认识不清,制约了油气勘探进程.笔者采用高精度重磁和电法CEMP综合物探技术对古牧地地区构造特征进行了研究,取得了有价值的新认识.研究成果表明,古牧地构造为博格达山前褶皱冲断带的前锋构造,受阶梯状断裂控制.古牧地构造纵向上具多层构造特征,其中浅层为紧闭型逆冲倒转背斜,中层为受阶状逆冲断层控制的屋脊状断块,深层为潜山披覆型冲断背斜.重力异常显示古牧地背斜西围斜可能是一完整的背斜构造,古牧地中深层构造和古牧地背斜西围斜评价为有利的油气勘探目标.     

Head/Tail Breaks: A New Classification Scheme for Data with a Heavy-Tailed Distribution

This article introduces a new classification scheme—head/tail breaks—to find groupings or hierarchy for data with a heavy-tailed distribution. The heavy-tailed distributions are heavily right skewed, with a minority of large values in the head and a majority of small values in the tail, commonly characterized by a power law, a lognormal, or an exponential function. For example, a country's population is often distributed in such a heavy-tailed manner, with a minority of people (e.g., 20 percent) in the countryside and the vast majority (e.g., 80 percent) in urban areas. This new classification scheme partitions all of the data values around the mean into two parts and continues the process iteratively for the values (above the mean) in the head until the head part values are no longer heavy-tailed distributed. Thus, the number of classes and the class intervals are both naturally determined. I therefore claim that the new classification scheme is more natural than the natural breaks in finding the groupings or hierarchy for data with a heavy-tailed distribution. I demonstrate the advantages of the head/tail breaks method over Jenks's natural breaks in capturing the underlying hierarchy of the data.     

The Geography of Mutual Fund Assets

Mutual funds are the primary investment vehicle for individual retirement savings, but the spatial aspects of mutual fund investments have not been examined. This paper discusses the characteristics of the mutual fund industry and compares them to other financial industries. Previous studies of the financial industry and quaternary location theory are used to formulate three hypotheses predicting the distribution of mutual fund assets: (1) mutual fund assets will concentrate in the largest urban centers; (2) mutual fund assets will become increasingly concentrated in financial centers over the 1986-1996 period; and (3) the distribution of mutual fund assets will be similar to the distribution of other financial activities. Examination of mutual fund asset data from 1986 and 1996 did not fully support any of the three hypotheses. These findings suggest that the standard elements of quaternary location theory may need to be reevaluated.     

Geography and Planning: Some Perspectives

This paper analyzes the migration of Puerto Rican-born women from the United States to Puerto Rico using longitudinal data. We hypothesize that sojourn length in the United States is a function of both structural (macro-level economic and cultural factors) and behavioral (micro-level life-cycle experiences and personal attributes) variables. We test these hypotheses by estimating a proportional hazards model. The parameter estimates of this model indicate that sojourn length in the United States, and thus the decision to return to Puerto Rico, is a function of wage trends and community characteristics on the mainland plus a number of individual attributes that include education, marriage, and childbirth.     

Population landscape: a geometric approach to studying spatial patterns of the US urban hierarchy

We present a geometric and graphic approach to studying spatial patterns of urban hierarchy in the US. The multiplicatively weighted Voronoi diagram is found to be effective for visualizing theoretical regions delineated by socio‐economic variables. The population landscape of the continental US demonstrates overall and stepwise patterns reflecting population, neighborhood and distance, with overwhelming influence from huge metropolitan areas. Stepwise exploration and cluster analysis of the spatial pattern reveal an urban hierarchy. Attributes and arrangement are the two important factors of urban hierarchy, with attribute having a stronger local influence and arrangement having a stronger global influence. The study also presents a variation of Zipf's law to visualize the rank‐size distribution from tabular and statistical space to map space.     

The temporal hierarchy of shelters: a hierarchical location model for earthquake-shelter planning

The problem of emergency facility location is a critical component in evacuation planning. The emergence of geographic information systems (GIS) has provided a useful operational platform to assist this issue. A previously overlooked facet is the consideration of a hierarchical structure in the placement of emergency shelters. Due to the fact that survivors' needs change over time during post-disaster evacuations, shelters have now been categorized on a temporal scale based on their functions at different evacuation phases. This article proposes a three-level hierarchical location model for optimizing the placement of earthquake shelters by taking into account this temporal variance. The article not only scrutinizes the modeling procedure but also implements the model in a planning area with many real-world details. Based on the optimization results derived from a GIS context, we have found that the quality of the earthquake response procedure is not only dependent on the placement strategy of shelters, but more importantly on the financial constraints imposed on the planning and construction of these shelters. A discussion has been proposed to balance the trade-off between budget planning and evacuation efficiency. As the first attempt to model the hierarchical configuration of emergency shelters with specific focus on evacuees' escalating sheltering demands, this article will be of great significance in helping policy makers consider both the spatial and financial aspects of the strategic placement of emergency shelters.     

Integration of linear and areal hierarchies for continuous multi-scale representation of road networks

Spatial data can be represented at different scales, and this leads to the issue of multi-scale spatial representation. Multi-scale spatial representation has been widely applied to online mapping products (e.g., Google Maps and Yahoo Maps). However, in most current products, multi-scale representation can only be achieved through a series of maps at fixed scales, resulting in a discontinuity (i.e., with jumps) in the transformation between scales and a mismatch between the available scales and users' desired scales. Therefore, it is very desirable to achieve smoothly continuous multi-scale spatial representations. This article describes an integrated approach to build a hierarchical structure of a road network for continuous multi-scale representation purposes, especially continuous selective omission of roads in a network. In this hierarchical structure, the linear and areal hierarchies are constructed, respectively, using two existing approaches for the linear and areal patterns in a road network. Continuous multi-scale representation of a road network can be achieved by searching in these hierarchies. This approach is validated by applying it to two study areas, and the results are evaluated by both quantitative analysis with two measures (i.e., similarity and average connectivity) and visual inspection. Experimental results show that this integrated approach performs better than existing approaches, especially in terms of preservation of connectivity and patterns of a road network. With this approach, efficient and continuous multi-scale selective omission of road networks becomes feasible.     

Comparison of adaptive structural damage identification techniques in nonlinear hysteretic vibration isolation systems

Early structural damage identification to obtain an accurate condition assessment can assist in the reprioritization of structural retrofitting schedules in order to guarantee structural safety. Nowadays, seismic isolation technology has been applied in a wide variety of infrastructure, such as buildings, bridges, etc., and the health conditions of these nonlinear hysteretic vibration isolation systems have received considerable attention. To effectively detect structural damage in vibration isolation systems based on vibration data, three time-domain analysis techniques, referred to as the adaptive extended Kalman filter （AEKF）, adaptive sequential nonlinear least-square estimation （ASNLSE） and adaptive quadratic sum-sqnares error （AQSSE）, have been investigated. In this research, these analysis techniques are compared in terms of accuracy, convergence and efficiency, for structural damage detection using experimental data obtained through a series of laboratory tests based on a base-isolated structural model subjected to E1 Centro and Kobe earthquake excitations. The capability of the AEKF, ASNLSE and AQSSE approaches in tracking structural damage is demonstrated and compared.