城市社会空间结构研究的回顾与展望   总被引：4，自引：0，他引：4  

王开泳  肖玲  王淑婧 《热带地理》2005,25(1):28-32

在城市社会空间结构方面介绍了西方和国内的主要研究成果,对城市社会空间结构的研究进展和领域作了综述。在总结社会空间结构理论基础和研究方法的基础上,全面回顾了城市社会空间研究的主要内容,并重点探讨城市社会空间结构的演变趋势和研究热点。认为今后要借鉴多学科的综合进行理论研究;社区建设与社区规划研究将成为热点;要重视居住空间分异与调控的研究;活动空间、感应空间及生活环境质量的研究将不断强化。  相似文献   

Environmental sensor networks for vegetation,animal and soil sciences     

A. Zerger  R.A. Viscarra Rossel  D.L. Swain  T. Wark  R.N. Handcock  V.A.J. Doerr  G.J. Bishop-Hurley  E.D. Doerr  P.G. Gibbons  C. Lobsey 《International Journal of Applied Earth Observation and Geoinformation》2010

Environmental sensor networks (ESNs) provide new opportunities for improving our understanding of the environment. In contrast to remote sensing technologies where measurements are made from large distances (e.g. satellite imagery, aerial photography, airborne radiometric surveys), ESNs focus on measurements that are made in close proximity to the target environmental phenomenon. Sensors can be used to collect a much larger number of measurements, which are quantitative and repeatable. They can also be deployed in locations that may otherwise be difficult to visit regularly. Sensors that are commonly used in the environmental sciences include ground-based multispectral vegetation sensors, soil moisture sensors, GPS tracking and bioacoustics for tracking movement in wild and domesticated animals. Sensors may also be coupled with wireless networks to more effectively capture, synthesise and transmit data to decision-makers. The climate and weather monitoring domains provide useful examples of how ESNs can provide real-time monitoring of environmental change (e.g. temperature, rainfall, sea-surface temperature) to many users. The objective of this review is to examine state-of-the-art use of ESNs for three environmental monitoring domains: (a) terrestrial vegetation, (b) animal movement and diversity, and (c) soil. Climate and aquatic monitoring sensor applications are so extensive that they are beyond the scope of this review. In each of the three application domains (vegetation, animals and soils) we review the technologies, the attributes that they sense and briefly examine the technical limitations. We conclude with a discussion of future directions.  相似文献   

Overview of the development history of China’s typhoon research and operational work in the past century     

Lei  Xiaotu 《中国科学:地球科学(英文版)》2020,63(3):362-383

Because typhoons are one of the most major natural disasters in the southeastern coastal areas of China,great attention has been paid to the prevention and mitigation of the disasters caused by typhoons.Over the past century,significant progress has been made in typhoon-related scientific research and operational work in China,including the construction of a network of typhoon monitoring stations,the establishment of forecasting operation systems,early warning and prevention of typhoon-related disasters,and the research of basic theories of typhoon behaviors and key forecasting technologies.This paper briefly reviews the milestones in the development history of typhoon research in China over the past century and a half in order to commemorate the predecessors,especially those who made historical contributions to the advancement of typhoon research since the economic and cultural reforms known as the"Opening of China",who provided historical references which enabled China to become an international leader in the field of typhoon science and technology.  相似文献   

地表蒸散定量遥感的研究进展   总被引：34，自引：1，他引：34  

辛晓洲  田国良  柳钦火 《遥感学报》2003,7(3):233-240

简要介绍了遥感监测地表蒸散和能量平衡研究的科学意义和应用价值，回顾了国内外的研究历史和现状，分析了目前该领域存在的一些问题和难点，并对今后的工作重点和研究方向提出了建议。  相似文献   

纳米钛酸锶及其系列功能材料研究概述   总被引：5，自引：0，他引：5       下载免费PDF全文

陈贞亮  杨金贤 《盐湖研究》1999,7(2):59-71

简要地叙述了钛酸锶及钛酸锶基纳米功能材料的制备、结构、性能及应用价值概况。并对其主要研究内容和国内外研究状况做了简单地介绍。  相似文献   

Support vector machines in remote sensing: A review   总被引：19，自引：0，他引：19  

Giorgos Mountrakis  Jungho Im  Caesar Ogole 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(3):247-259

A wide range of methods for analysis of airborne- and satellite-derived imagery continues to be proposed and assessed. In this paper, we review remote sensing implementations of support vector machines (SVMs), a promising machine learning methodology. This review is timely due to the exponentially increasing number of works published in recent years. SVMs are particularly appealing in the remote sensing field due to their ability to generalize well even with limited training samples, a common limitation for remote sensing applications. However, they also suffer from parameter assignment issues that can significantly affect obtained results. A summary of empirical results is provided for various applications of over one hundred published works (as of April, 2010). It is our hope that this survey will provide guidelines for future applications of SVMs and possible areas of algorithm enhancement.  相似文献   

The Geological Conservation Review (GCR) in Great Britain—Rationale and methods     

Neil Ellis 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(3):353-362

Geoconservation – protecting, managing and enhancing natural geological features and materials, and geomorphological landforms and processes – is especially important in Great Britain, a place sometimes described as the ‘cradle’ of the science of geology. For such a small area of land, Britain has an unusually diverse geological make-up, with rocks from every geological period present. Many stratigraphical terms used internationally were devised here, and British sites provide key study areas where important new geological theories were developed in the pioneering era of the Earth sciences. Therefore, with such a wealth of geology, and Britain's seminal place in the science itself, it is particularly important to conserve and protect key localities here for future generations. A first step in that process is the auditing of the geology and geomorphology of Britain, by carrying out a scientific evaluation exercise according to standard criteria, and creating an inventory of the most important sites for science.In the mid-1970s, the Nature Conservancy Council (NCC) began an ambitious programme for assessment and documentation of the most important sites for the scientific study of geology and geomorphology in Great Britain, building on previous statutory site conservation activity that had already been started in 1949 by the former Nature Conservancy. As a result, the ‘Geological Conservation Review’ (GCR) was formally launched in 1977. The GCR was a world-first project of its type in the systematic assessment of the whole geological heritage of a country, from first principles. Widespread consultation with geologists and geomorphologists across Great Britain was co-ordinated; their guidance and involvement was a key component of the site selection process. Almost 3000 nationally or internationally important sites had been selected for around 100 site-selection categories for the GCR register by 1990. Almost all the GCR sites are now conserved under British law as Sites of Special Scientific Interest (SSSIs), the GCR information providing the scientific evidence-base that underpins that designation.As part of the site-selection process – which is still active – a considerable archive of information about geological sites was amassed. A major publication exercise detailing all the GCR sites in what was to become the GCR Series of books was devised early on in the GCR programme.Thirty-six volumes of the GCR Series have been seen to completion by NCC and the Joint Nature Conservation Committee, and many GCR site reports have been many made freely available on the World Wide Web. As a new venture, the remaining nine volumes will now be published by Elsevier Science Publishers as Special Issues of the Proceedings of the Geologists’ Association. Each GCR volume includes an overview of the subject and outlines the history of study of the relevant branch of the Earth sciences, but most importantly contains detailed accounts of the features of geological importance in the sites described. A scientific interpretation is provided for each site account, which includes supportive illustrations, tables and photographs and an extensive reference list.The GCR rationale, methods and information resource have been invaluable in almost every aspect of geoconservation carried out in Britain, including World Heritage Site nominations, protection of stratotypes, justifying the scientific conservation value of sites at Public Inquiries, in stimulating geological research and in providing a readily available information resource for local, regional, national and international geoconservation activities.  相似文献   

CBM and CO2-ECBM related sorption processes in coal: A review   总被引：1，自引：0，他引：1  

Andreas Busch  Yves Gensterblum 《International Journal of Coal Geology》2011,87(2):49-71

This article reviews the state of research on sorption of gases (CO₂, CH₄) and water on coal for primary recovery of coalbed methane (CBM), secondary recovery by an enhancement with carbon dioxide injection (CO₂-ECBM), and for permanent storage of CO₂ in coal seams.Especially in the last decade a large amount of data has been published characterizing coals from various coal basins world-wide for their gas sorption capacity. This research was either related to commercial CBM production or to the usage of coal seams as a permanent sink for anthropogenic CO₂ emissions. Presently, producing methane from coal beds is an attractive option and operations are under way or planned in many coal basins around the globe. Gas-in-place determinations using canister desorption tests and CH₄ isotherms are performed routinely and have provided large datasets for correlating gas transport and sorption properties with coal characteristic parameters.Publicly funded research projects have produced large datasets on the interaction of CO₂ with coals. The determination of sorption isotherms, sorption capacities and rates has meanwhile become a standard approach.In this study we discuss and compare the manometric, volumetric and gravimetric methods for recording sorption isotherms and provide an uncertainty analysis. Using published datasets and theoretical considerations, water sorption is discussed in detail as an important mechanisms controlling gas sorption on coal. Most sorption isotherms are still recorded for dry coals, which usually do not represent in-seam conditions, and water present in the coal has a significant control on CBM gas contents and CO₂ storage potential. This section is followed by considerations of the interdependence of sorption capacity and coal properties like coal rank, maceral composition or ash content. For assessment of the most suitable coal rank for CO₂ storage data on the CO₂/CH₄ sorption ratio data have been collected and compared with coal rank.Finally, we discuss sorption rates and gas diffusion in the coal matrix as well as the different unipore or bidisperse models used for describing these processes.This review does not include information on low-pressure sorption measurements (BET approach) to characterize pore sizes or pore volume since this would be a review of its own. We also do not consider sorption of gas mixtures since the data base is still limited and measurement techniques are associated with large uncertainties.  相似文献   

2020年震情述评     

解孟雨  韩颜颜  臧阳  马亚伟  邓世广  王月  宋金  张小涛  姜祥华  史海霞  杨文 《中国地震》2021,37(1):249-254

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江山如此多娇——2011年中美非开挖行业发展回顾与展望     

颜纯文  朱晓艳 《岩土钻凿工程》2012,(2):1-8

2011年,发达国家受主权债务危机影响,新兴经济体通货膨胀压力上升,各国经济增速普遍下滑在这样的大环境下,我国非开挖行业仍取得了骄人的成绩。本文首先概述了2011年在我国非开挖行业影响较大的重大事件,然后较详细地介绍了中关两国非开挖市场的调查情况,包括中美水平定向钻机情况和美国市政管线建设投资情况,最后对未来我国非开挖行业的发展趋势进行了预测。  相似文献