基于DEM的沟谷系统提取算法综述

该文对近20多a来基于栅格数字高程模型(DEM)提取沟谷系统的方法与技术进行了综述。将沟谷系统提取方法归纳为三类：局部方法、全局方法、局部与全局相结合的方法，比较了各类方法的优缺点。分别综述与比较了提取沟谷系统的三个主要问题——水流路径的确定、洼地的处理以及累计汇流阈值的确定的解决算法以及存在的不足。笔者认为要使这方面的研究走向真正的实用化，必须借助其它的信息，利用人工智能和模式识别等多种手段来实现自动提取。     

神经网络在气象观测资料优化中的应用研究

利用一种改进的BP算法，对气象观测资料进行优化处理，并把神经网络方法看作是时间序列方法的扩充。利用该算法提出了基于空间相关、时间相关、模式相关三种资料优化处理方案，为气象观测资料的优化提供了一条新方法。利用文中的方法，对黑河地区的观测资料进行了修正实验，取得了比较满意的结果。     

The Break-up of a Long-term Relationship: the Cretaceous Separation of New Zealand from Gondwana

After a prolonged period of convergent margin tectonics in the Late Paleozoic and Mesozoic, resulting in terrane accretion, uplift and erosion of the New Zealand segment of Gondwana, the region saw a rapid change to extensional tectonics in mid-Cretaceous times. The change in regime is commonly marked by a major angular unconformity that separates the older, often strongly-deformed subduction-related ‘basement’ rocks from the younger, less-deformed ‘cover’ strata. The youngest ‘basement’ strata locally contain Albian fossils, and the youngest associated zircons have been radiometrically dated at ca. 100 Ma. In general the oldest strata overlying the unconformity contain fossils of similar Albian age, and the oldest radiometric dates also give similar dates of ca. 100 Ma, indicating a very rapid transition between the two tectonic regimes.The onset of extension resulted in the widespread development of grabens and half grabens, associated in the northwest of the South Island with a metamorphic core complex. In the west and south, on the thicker and more buoyant crust of most of the South Island, the new basins were infilled with mainly non-marine deposits. Non-marine graben infill consists of locally-derived breccia deposited as talus or debris flows on alluvial fans, passing directly as fan deltas or via fluvial deposits into lacustrine deposits. Active faulting continued in some areas until the initiation of sea floor spreading in Santonian times. Post-subduction strata on the thinner continental crust of the northeastern South Island and eastern North Island (East Coast Basin) were mainly marine. Initial sedimentary deposits in the west of the basin, reflecting extensional tectonism, consist of coarse-grained debris-flow deposits or olistostromes, generally fining upwards as tectonic activity waned: those in the east, including allochthonous sediments derived from the northeast, are dominated by turbidites. Early Cenomanian (ca. 96–98 Ma) injection of intraplate alkaline igneous rocks in central New Zealand caused updoming, resulting in shallowing and local uplift of the basin floor above sea level. A long (ca. 10 Ma) period of slow subsidence and transgressive marine sedimentation interrupted by episodic relative sea level changes followed.This pattern changed in the Late Coniacian (ca. 87–86 Ma), with a sudden influx of coarse, transgressive sands in eastern New Zealand. This was immediately preceded in parts of the region by uplift and erosion, probably driven by convective upwelling of the mantle just prior to sea-floor spreading, resulting in a ‘break-up’ unconformity. In the Late Santonian (ca. 85–84 Ma), development of a new, diachronous, widespread low-relief erosion surface, overlain by fine-grained deposits accompanying a rapid rise in relative sea level, coincided with the beginning of sea-floor spreading, rapid passive margin subsidence, and final separation of New Zealand from Gondwana.     

Comparison of Kriging and Neural Networks With Application to the Exploitation of a Slate Mine

To carry out an efficient and effective exploitation of a slate mine, it is necessary to have detailed information about the production potential of the site. To assist us in estimating the quality of slate from a small set of drilling data within an unexploited portion of the mine, the following estimation techniques were applied: kriging, regularization networks (RN), multilayer perceptron (MLP) networks, and radial basis function (RBF) networks. Our numerical results for the test holes show that the best results were obtained using an RN (kriging) which takes into account the known anisotropy. Differing deposit configurations were obtained, depending on the method applied. Variations in the form of pockets were obtained when using a radial pattern with RBF, RN, and kriging models while a stratified pattern was obtained with the MLP model. Pockets are more suitable for a slate mine, which indicates that the selection of a technique should take account of the specific configuration of the deposit according to mineral type.     

利用多分辨率小波网络方法进行伪井反演

利用小波网络,对地震资料和小波多尺度分解属性资料,进行了虚井声波时差反演.讨论了利用地震信号的小波分解和网络学习、训练的理论方法.为了提高反演分辨率和精度，研究了信号分段相似小波时—频分析技术方法.在对对这些技术方法综合研究和算法的实现设计以后，对实际资料进行了反演计算，并对反演结果进行验证.取得了很好的效果.     

Landslide susceptibility mapping: A comparison of logistic regression and neural networks methods in a medium scale study, Hendek region (Turkey)

Landslide susceptibility mapping is one of the most critical issues in Turkey. At present, geotechnical models appear to be useful only in areas of limited extent, because it is difficult to collect geotechnical data with appropriate resolution over larger regions. In addition, many of the physical variables that are necessary for running these models are not usually available, and their acquisition is often very costly. Conversely, statistical approaches are currently pursued to assess landslide hazard over large regions. However, these approaches cannot effectively model complicated landslide hazard problems, since there is a non-linear relationship between nature-based problems and their triggering factors. Most of the statistical methods are distribution-based and cannot handle multisource data that are commonly collected from nature. In this respect, logistic regression and neural networks provide the potential to overcome drawbacks and to satisfy more rigorous landslide susceptibility mapping requirements. In the Hendek region of Turkey, a segment of natural gas pipeline was damaged due to landslide. Re-routing of the pipeline is planned but it requires preparation of landslide susceptibility map. For this purpose, logistic regression analysis and neural networks are applied to prepare landslide susceptibility map of the problematic segment of the pipeline. At the end, comparative analysis is conducted on the strengths and weaknesses of both techniques. Based on the higher percentages of landslide bodies predicted in very high and high landslide susceptibility zones, and compatibility between field observations and the important factors obtained in the analyses, the result found by neural network is more realistic.     

A site of transnationalism in the “Ungrounded Empire”: Taipei as an interface city in the cross-border business networks

This paper explores the dynamics of the economic development of Taipei City under conditions of globalization. Although Taipei City had undergone rapid industrialization and exploited the rural-urban division of labor since at least the 1960s, the city’s economic base changed dramatically after 1980. Initiating a process of industrial restructuring, the nation state encouraged high technology industries to help upgrade Taipei City’s role within global production chains. It was the transnational connection that kept regional growth within high ‘value-added’ activities. Instead of relying on a few major transnational corporations as the key agents of internationalization, Taipei City transformed itself into a node for high-technology knowledge, which connected the city with high-technology hubs elsewhere, and to Silicon Valley in particular, through transnational technical communities. At the same time, companies headquartered in the city extended their production chains across the Taiwan Strait to locate production facilities in the major coastal cities of mainland China. In consequence, Taipei City became a nodal city in these cross-border connections. These developments illustrate the limits of global city discourses which fail to pay sufficient attention to the role of developmental states and transnationalism in the process of global transformation.     

Heterolocalism,Networks of Ethnicity,and Refugee Communities in the Pacific Northwest: The Portland Story*

Geographic studies of refugee issues have emerged as salient topics of inquiry in the past decade. This spatial analysis of the migration experiences and heterolocal settlement patterns of refugees in an increasingly diverse part of the Pacific Northwest focuses on a place that the Atlantic Monthly recently called the last Caucasian bastion in the United States. Perceived as a region better known for its dense forests, progressive environmental policies, and rural ambience, the Portland metropolitan area and its hinterland in the Willamette Valley now resonate with ethnic and racial diversity. This article analyzes the spatial patterns and related networks of the three largest refugee groups in the region. Findings indicate that an overlapping and interrelated set of political, social, cultural, and economic networks are the most important factors in determining refugee residential patterns.     

Diatom-based inference models and reconstructions revisited: methods and transformations

Different calibration methods and data manipulations are being employed for quantitative paleoenvironmental reconstructions, but are rarely compared using the same data. Here, we compare several diatom-based models [weighted averaging (WA), weighted averaging with tolerance-downweighting (WAT), weighted averaging partial least squares, artificial neural networks (ANN) and Gaussian logit regression (GLR)] in different situations of data manipulation. We tested whether log-transformation of environmental gradients and square-root transformation of species data improved the predictive abilities and the reconstruction capabilities of the different calibration methods and discussed them in regard to species response models along environmental gradients. Using a calibration data set from New England, we showed that all methods adequately modelled the variables pH, alkalinity and total phosphorus (TP), as indicated by similar root mean square errors of prediction. However, WAT had lower performance statistics than simple WA and showed some unusual values in reconstruction, but setting a minimum tolerance for the modern species, such as available in the new computer program C² version 1.4, resolved these problems. Validation with the instrumental record from Walden Pond (Massachusetts, USA) showed that WA and WAT reconstructed most closely pH and that GLR reconstructions showed the best agreement with measured alkalinity, whereas ANN and GLR models were superior in reconstructing the secondary gradient variable TP. Log-transformation of environmental gradients improved model performance for alkalinity, but not much for TP. While square-root transformation of species data improved the performance of the ANN models, they did not affect the WA models. Untransformed species data resulted in better accordance of the TP inferences with the instrumental record using WA, indicating that, in some cases, ecological information encoded in the modern and fossil species data might be lost by square-root transformation. Thus it may be useful to consider different species data transformations for different environmental reconstructions. This study showed that the tested methods are equally suitable for the reconstruction of parameters that mainly control the diatom assemblages, but that ANN and GLR may be superior in modelling a secondary gradient variable. For example, ANN and GLR may be advantageous for modelling lake nutrient levels in North America, where TP gradients are relatively short.