倾角分解共反射面元叠加方法   总被引：13，自引：4，他引：9       下载免费PDF全文

杨锴  许士勇  王华忠  马在田 《地球物理学报》2005,48(5):1148-1155

共反射面元（Common Reflection Surface）叠加是一种独立于宏观速度模型的零偏移距剖面成像方法,传统的CRS叠加实现是以数据驱动的方式对属性参数进行自动搜索并对其进行优化合成相应的CRS叠加算子,通过该算子进行叠加能够得到信噪比和连续性更高的零偏移距剖面.但是数据驱动的实现方式带来了不可避免的“倾角歧视现象”,它造成了弱有效反射信号损失和运动学特征失真的问题.本文提出的倾角分解CRS叠加方法成功解决了上述问题,使CRS叠加方法更具实用价值.  相似文献   

Common sense principles governing potable water recycling in the southwestern US: Examining subjectivity of water stewards using Q methodology     

《Geoforum》2017

The potential to supplement potable water supplies with highly treated municipal wastewater, or sewage, is of increasing interest to water planners in many parts of the world. Most of the current social science focuses on public acceptance, however there is a relative lack of research that explores the subjectivity of people who are involved with water recycling or water planning. This study draws on Gramscian theories of governance and Q Methodology to analyze common sense principles that are held by water stewards who currently govern potable water reuse in the southwestern United States. Two competing perspectives emerged from the analyses, which I label neosanitarian and ecosanitarian. Drawing upon tenets established in the Progressive Era, neosanitarians believe that use of recycled water is an appropriate way to expand urban drinking water supplies. Drawing upon tenets established in ecology, ecosanitarians are not opposed to potable water recycling, however they are also interested in radical alternatives to the sanitary status quo. For example, neosanitarians favor advanced wastewater treatment, while ecosanitarians prefer composting toilets and preventative actions. Differences between the common sense views pivot on ideas about the most appropriate technology but also reflect contested visions of ideal society.  相似文献   

陆面模式中土壤和植被经验参数随机误差的传播研究   总被引：3，自引：1，他引：2  

梁晓  戴永久 《大气科学》2010,34(2):457-470

数据质量问题和模式参数化方案的非完备性是陆面模拟中不确定性的主要来源。本文将高斯误差传播原理 (Gaussian Error Propagation, GEP) 应用于通用陆面模式 (the Common Land Model, CoLM), 研究关键的植被和土壤属性参数随机误差在模式中的传播, 确定由此类误差导致的CoLM模拟的不确定性。结果表明: (1) 基于本研究给定的土壤和植被参数的不确定性, CoLM模拟的表层土壤温度、 土壤湿度和植被蒸散通量 (植冠蒸腾+地表蒸发) 的相对误差分别为0.11%、 34.07%和5.58%; 砂土和稀疏森林上模拟效果最差。土壤参数随机误差对CoLM模拟的影响高于植被参数, 而土壤水文参数 (孔隙率、 饱和基质势、 气孔尺寸分布指数和饱和导水率) 对各模拟量不确定性的贡献率均远大于热力参数 (饱和反照率和热容)。对于本研究涉及的所有模拟变量而言, 最关键的参数均是气孔尺寸分布指数b, 这可能与描述基质势与体积水含量关系的函数有关, 其次重要的是砂土的孔隙度和粘土的饱和导水率。混交森林上的根深分布和苔原上的动力学粗糙度对蒸散通量贡献显著。本身相对误差大的经验参数对CoLM模拟不确定性的贡献不一定多。 (2) 干燥条件下 (表层液态水饱和度小于0.1) 土壤温度的不确定性大; 相变发生时刻附近 (表层土壤温度在0℃附近且表层液态水含量大于0) 土壤湿度不确定性显著; 蒸散通量的不确定性随本身绝对值的增大而增大, 在相对温暖干燥环境中 (表层土壤温度高于280 K且表层液态水饱和度小于0.3) 其不确定性最高。研究证实, GEP能够辨识CoLM中需优先提高观测精度的关键参数和关键参数化过程, 对陆面模拟的参数选定、 不确定性评估和模式完善具有重要意义。  相似文献   

基于Geodatabase极地NetCDF验潮数据的存储与分析     

马林波  张洪文  朱李忠  金丽华  宿裕 《测绘工程》2012,21(2):43-45

针对MATLAB读取南极验潮数据所出现的问题以及南极验潮数据本身的特点,结合ArcGIS9.2推出的Multidimension Tools和Geodatabase,设计出NetCDF格式的南极验潮站数据存储和处理的一般流程,并利用MATLAB混合编程的数值计算和分析功能,有效地对南极验潮数据进行存储管理和分析,为NetCDF格式的地理数据的读取、存储提供一种解决的思路。  相似文献   

A new perspective in identifying the precursory patterns of eruptions   总被引：2，自引：2，他引：0  

Laura?SandriEmail author  Warner?Marzocchi  Lucia?Zaccarelli 《Bulletin of Volcanology》2004,66(3):263-275

The complexity of the processes responsible for volcanic eruptions makes a theoretical approach to forecasting the evolution of volcanic unrest rather difficult. A feasible strategy for this purpose appears to be the identification of possible repetitive schemes (patterns) in the pre-eruptive unrest of volcanoes. Nevertheless, the limited availability and the heterogeneity of pre-eruptive data, and the objective difficulty in quantitatively recognizing complex pre-eruptive patterns, make this task very difficult. In this work we address this issue by using a pattern recognition approach applied to the seismicity recorded during 217 volcanic episodes of unrest around the world. In particular, we use two non-parametric algorithms that have proven to give satisfactory results in dealing with a small amount of data, even if not normally distributed and/or characterized by discrete or categorical values. The results show evidence of a longer period of instability in the unrest preceding an eruption, compared to isolated unrest. This might indicate, even if not necessarily, a difference in the energy of processes responsible for the two types of unrest. However, if the unrest is followed by an eruption, it seems that the seismic energy released during the unrest (parameterized by the duration of the swarm and the maximum magnitude recorded) is not indicative of the magnitude of the impending eruption. We also found that, in general, unrest followed by the largest explosive eruptions have a longer repose time than those related to moderate eruptions. This evidence supports the fact that the occurrence of a large eruption needs a sufficient amount of time after the last event in order to re-charge the feeding system and to achieve a closed-conduit regime so that a sufficiently large amount of gas can be accumulated.Editorial responsibility: T. Druitt  相似文献   

Molecular cloning and mRNA expression of cytochrome P4501A1 and 1A2 in the liver of common minke whales (Balaenoptera acutorostrata)     

Niimi S  Watanabe MX  Kim EY  Iwata H  Yasunaga G  Fujise Y  Tanabe S 《Marine pollution bulletin》2005,51(8-12):784-793

This study presents full-length cDNA sequences of CYP1A1 and 1A2, in common minke whale (Balaenoptera acutorostrata) from the North Pacific. Both CYP1A1 and CYP1A2 cDNAs had an open reading frame of 516 amino acid residues, and predicted molecular masses were 58.3 kDa and 58.1 kDa, respectively. The deduced full-length amino acid sequence of CYP1A1 revealed higher identities with those of sheep (86%) and pig (87%), and that of CYP1A2 was most closely related to human (82%) and monkey CYP1A2 (82%) among species from which CYP1A2 has been isolated so far. Differences in certain conserved and functional amino acid residues of CYP1A1 and 1A2 between common minke whale and other mammalian species indicate the possibility of their specific metabolic function. Concentrations of organochlorine compounds (OCs) including PCBs and DDTs analyzed in common minke whale liver showed no significant correlation with hepatic mRNA expression levels of CYP1A1 and CYP1A2, indicating no induction of these enzymes by such OCs.  相似文献   

基于Windows NT服务器的前兆数据共享及其实现   总被引：3，自引：2，他引：3  

米宏亮  李圣强  杨满栋  李闽峰  姜立新  宋喜先  赵育浦 《地震》2001,21(4):112-117

简要介绍了地震前兆数据的现状及其实现数据共享的必要性；分析了常用的二种通用Web数据库的体系结构及应用技术，它们是基于通用网关接口CGI的体系结构和基于服务器扩展API的体系结构。考虑到前兆台网中心硬件设备的条件、所运行的数据库平台和地震前兆数据的复杂性和多样性特点，前兆数据在Internet上的共享服务采用基于通用网关接口CGI的体系结构编写应用程序来实现。以WWW服务器为平台，通过Web服务器方式在浏览器上实现共享，可检索任意台站、任意观测方法、任意地点、任意时段的前兆数据，实现地震前兆数据信息网络服务功能。  相似文献   

地形测量中两个常用公式的探讨   总被引：1，自引：0，他引：1  

王同合 《测绘学院学报》1995,(3)

本文对地形测量中两个常用的公式进行了探讨，提高了它们的实用性及理论上的严密性，并对《城市测量规范》提出一点建设性意见。  相似文献   

Community Forest Owners Evaluate a Decade of Payments for Ecosystem Services in the Mexican Cloud Forest: The Importance of Attention to Indigenous Sovereignty in Conservation     

Diana Denham 《社会与自然资源》2017,30(9):1064-1079

Payments for ecosystem services (PES) programs have taken a variety of forms that depend on many mediating factors, such as national and local politics, land tenure, regional collective action, the capacity of intermediaries, and socio-ecological context. This diversity has produced unsurprisingly mixed experiences, with many falling short of achieving the twin goals of environmental and social benefits and some causing adverse consequences. This study examines one rare PES case that has contributed both to forest conservation and to community livelihoods. In this study, community forest owners from four indigenous communities in the Mexican cloud forest evaluate their participation in ten years of a public PES program to support watershed stewardship. We argue that attention to indigenous sovereignty and self-determination in program implementation contributed to widely appreciated socio-environmental benefits. Though many PES programs are implemented in indigenous communities, scholarly debates have rarely dealt directly with these issues.  相似文献   

The EU landing obligation and European small-scale fisheries: What are the odds for success?     

《Marine Policy》2016

A landing obligation was formally implemented in the European Union (EU) for the first time, as part of the recent reform of the EU Common Fisheries Policy (CFP). Given the reasonable success of the landing obligation in some countries such as the Faroe Islands, Iceland and Norway, this policy is seen as a viable approach to tackle the long-recognized discarding problem in EU waters. However, there has been some debate on whether there is sufficient evidence to support the feasibility of such a measure in the EU-CFP. The EU landing obligation will implicitly include all small-scale fisheries (SSF) provided the species captured are subject to catch limits or minimum sizes (in the case of the Mediterranean). SSF were included irrespective of the fact that the discarding problem in the EU has been historically associated with medium- to large-scale fleets (in particular largely mixed species trawl fisheries). Additionally, past experiences with a discard ban policy are still limited to specific countries and/or specific fisheries. This paper examined the appropriateness and feasibility of the recently implemented EU landing obligation in SSF. The effects in the long-term are unpredictable, but available evidence suggests that in the short to medium-term a landing obligation is likely to bring more negative social, economic and ecological impacts than benefits.  相似文献