中国数字地震台网数字化地震资料使用指南

由于数字地震记录仪具有记录频带宽,分辨率高,动态范围大以及易于用计算机处理等优点,所以数字地震台网产出的数字地震资料成为地震活动性,震源机制,地球内部研究,地震监测及预报等的最基本数据源。     

Concentration–discharge relationships reflect chemostatic characteristics of US catchments

Concentration–discharge relationships have been widely used as clues to the hydrochemical processes that control runoff chemistry. Here we examine concentration–discharge relationships for solutes produced primarily by mineral weathering in 59 geochemically diverse US catchments. We show that these catchments exhibit nearly chemostatic behaviour; their stream concentrations of weathering products such as Ca, Mg, Na, and Si typically vary by factors of only 3 to 20 while discharge varies by several orders of magnitude. Similar patterns are observed at the inter‐annual time scale. This behaviour implies that solute concentrations in stream water are not determined by simple dilution of a fixed solute flux by a variable flux of water, and that rates of solute production and/or mobilization must be nearly proportional to water fluxes, both on storm and inter‐annual timescales. We compared these catchments' concentration–discharge relationships to the predictions of several simple hydrological and geochemical models. Most of these models can be forced to approximately fit the observed concentration–discharge relationships, but often only by assuming unrealistic or internally inconsistent parameter values. We propose a new model that also fits the data and may be more robust. We suggest possible tests of the new model for future studies. The relative stability of concentration under widely varying discharge may help make aquatic environments habitable. It also implies that fluxes of weathering solutes in streams, and thus fluxes of alkalinity to the oceans, are determined primarily by water fluxes. Thus, hydrology may be a major driver of the ocean‐alkalinity feedback regulating climate change. Copyright © 2009 John Wiley & Sons, Ltd.     

地理信息系统中的网络模型

社会中的很多空间现象,如交通、信息交流和生活消费品的运输等都是线性的。在ARC INFO地理信息系统(GIS)中,这些线性现象经过组织和处理,能够建立成网络及其数据库。从而可用来解决资源的合理分配和流动、交通运输中的最佳路线选择等问题。     

2.4m望远镜网络安全初步设计

云南天文台将在2.4m望远镜建立远程观测系统。由于远程观测系统通过网络实现通信,必然会面临网络上的各种威胁。为了保证整个网络系统的安全,避免各种不安全因素造成的损失。在对现在望远镜网络分析基础上设计了安全的网络结构,并实现了具有入侵检测功能的防火墙,这些措施初步保障了2.4m望远镜网络系统的安全。     

A trophic model for the Danshuei River Estuary, a hypoxic estuary in northern Taiwan

The estuary of the Danshuei River, a hypoxic subtropical estuary, receives a high rate of untreated sewage effluent. The Ecopath with Ecosim software system was used to construct a mass-balanced trophic model for the estuary, and network analysis was used to characterize the structure and matter flow in the food web. The estuary model was comprised of 16 compartments, and the trophic levels varied from 1.0 for primary producers and detritus to 3.0 for carnivorous and piscivorous fishes. The large organic nutrient loading from the upper reaches has resulted in detritivory being more important than herbivory in the food web. The food-chain length of the estuary was relatively short when compared with other tropical/subtropical coastal systems. The shortness of food-chain length in the estuary could be attributed to the low biomass of the top predators. Consequently, the trophic efficiencies declined sharply for higher trophic levels due to low fractions of flows to the top predators and then high fractions to detritus. The low biomass of the top predators in the estuary was likely subject to over-exploitation and/or hypoxic water. Summation of individual rate measurements for primary production and respiration yielded an estimate of −1791 g WW m⁻² year⁻¹, or −95 g C m⁻² year⁻¹, suggesting a heterotrophic ecosystem, which implies that more organic matter was consumed than was produced in the estuary.     

Some things old, some things new: The spatial representations and politics of change of the peak oil relocalisation movement

Despite continued uncertainty about the physical realities and political, economic and social implications of peak oil, combined concerns about oil scarcity, climate change and globalisation has spawned an energetic relocalisation movement dedicated to achieving a comprehensive reduction in oil dependency through community-scale initiatives. This paper uses a discourse approach to examine the emergence, geographical spread and practices of the Transition Network, a UK-originated relocalisation movement now involving 186 local initiatives in the UK and other countries. We trace the movement’s drawing upon, and innovation from, discourses and techniques used by other grassroots environmental movements to promote a spatial representation of peak oil as an inevitable and geographically undiscriminating problem, and its use of addiction metaphors and participatory techniques to promote personal and community-scale energy descent initiatives as a viable and necessary alternative to globalisation. We also analyse the spatial representations and techniques used in the Network’s “rhizomic” spread across multiple localities around the world and embedding in communities where relocalisation initiatives are established. We conclude by examining the future challenges these spatial constructions of peak oil pose for the relocalisation movement.     

广西寒露风开始期短期气候预测方法研究

利用1951-2013年广西90个气象观测站气温资料、国家气候中心74项指数和美国National Oceanic and Atmospheric Administration（NOAA）的Climate Prediction Center（CPC）60项指数以及海温和陆地雪盖资料、美国国家冰雪研究中心（NSIDC）的两极海冰资料,使用相关分析方法得到广西寒露风开始期气候影响因子,利用逐步回归和神经网络方法进行寒露风开始期的预测。结果表明：寒露风开始期与前一年9-10月北极海冰面积、当年3月南极海冰面积、前一年6月欧亚雪盖、当年5月北美雪盖、北半球雪盖的相关显著。与前一年9月北半球极涡面积指数、前一年10月亚洲区极涡面积指数、前一年3月热带印度洋海温偶极子等指数相关显著。粒子群-神经网络方法预测误差低于逐步回归方法,预报能力有明显提高。     

Assessing the performance of two unsupervised dimensionality reduction techniques on hyperspectral APEX data for high resolution urban land-cover mapping

Despite the high richness of information content provided by airborne hyperspectral data, detailed urban land-cover mapping is still a challenging task. An important topic in hyperspectral remote sensing is the issue of high dimensionality, which is commonly addressed by dimensionality reduction techniques. While many studies focus on methodological developments in data reduction, less attention is paid to the assessment of the proposed methods in detailed urban hyperspectral land-cover mapping, using state-of-the-art image classification approaches. In this study we evaluate the potential of two unsupervised data reduction techniques, the Autoassociative Neural Network (AANN) and the BandClust method – the first a transformation based approach, the second a feature-selection based approach – for mapping of urban land cover at a high level of thematic detail, using an APEX 288-band hyperspectral dataset. Both methods were tested in combination with four state-of-the-art machine learning classifiers: Random Forest (RF), AdaBoost (ADB), the multiple layer perceptron (MLP), and support vector machines (SVM). When used in combination with a strong learner (MLP, SVM) BandClust produces classification accuracies similar to or higher than obtained with the full dataset, demonstrating the method’s capability of preserving critical spectral information, required for the classifier to successfully distinguish between the 22 urban land-cover classes defined in this study. In the AANN data reduction process, on the other hand, important spectral information seems to be compromised or lost, resulting in lower accuracies for three of the four classifiers tested. Detailed analysis of accuracies at class level confirms the superiority of the SVM/Bandclust combination for accurate urban land-cover mapping using a reduced hyperspectral dataset. This study also demonstrates the potential of the new APEX sensor data for detailed mapping of land cover in spatially and spectrally complex urban areas.     

The emergent network structure of the multilateral environmental agreement system

The conventional piecemeal approach to environmental treaty-making has resulted in a ‘maze’ of international agreements. However, little is known empirically about its overall structure and evolutionary dynamics. This study reveals and characterizes the evolving structure of the web of international environmental treaty law. The structure was approximated using 1001 cross-references among 747 multilateral environmental agreements concluded from 1857 to 2012. Known network analysis measures were used to answer the following questions: has a complex system of international environmental treaty law emerged? If so when, and what does it look like? What are its topological properties? To what extent is the institutional complex fragmented? The network analysis suggested that multilateral environmental agreements have self-organized into an interlocking system with a complex network structure. Furthermore, the system has defragmented as it coevolved with the increasing complexity and interconnectivity of global environmental challenges. This study demonstrates the need to approach multilateral environmental agreements in the context of a complex networked system, and recommends against assuming the overall institutional structure is fragmented. Proposals for global environmental governance reform should pay attention to this network's emergent polycentric order and complexity and to the implications of these features for the functioning of the multilateral environmental agreement system.     

小型局域网络系统的扩展设计

采用混合方式的网络拓扑结构和内部网桥技术，以低廉的投资实现了一个网络覆盖范围较大、能跨越多栋办公大楼的小型局域网络。该网络电缆距离的延伸较长，布线灵活，网段间隔离性好，不仅可以提高网络传输效率，易于检测判断故障，而且运行安全可靠，是一种有效的计算机小型局域网络设计／改造方案