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地表覆盖是地理国情普查的主要内容之一,针对其空间分布格局问题,提出了基于景观要素特征-景观空间格局-景观空间构型的景观健康分析与评价模型。结合GIS技术和Fragstats软件,基于2014年地理国情普查试点数据,利用层次分析法和综合指数法,对地表覆盖的景观格局健康状况进行分析与评价。结果表明,试验区的景观结构与格局健康水平较低,其原因主要是水域景观要素特征与景观空间格局的健康水平、草地景观要素特征与景观空间构型的健康水平都较低。  相似文献   

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"How one conceptualises the impacts of migration depends on whether one takes the viewpoint of aggregate area-level income change, of per capita change, or of longer-term (future earnings) change. Several empirical analytical measures are proposed in order to conceptualise the various income impacts of migration.... [A] decomposition procedure is developed for examining how the changes in per capita income of states reflect three different income differentials: those between (a) in-migrants and 'stayers', (b) out-migrants and 'stayers', and (c) in-migrants and out-migrants. Examination of these measures, and of typologies based on them, highlights how income migration significantly and differentially impacts upon U.S. states. The methods are illustrated here in the context of an important new American data source: the 1993-94 migrant income data released by the U.S. Internal Revenue Service."  相似文献   

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人口统计数据空间化模型综述   总被引:3,自引:0,他引:3  
人口统计数据空间化是人口信息与其他资源环境、社会经济等信息进行空间集成的基础.本研究对国内外人口统计数据空间化研究进行总结,归纳了水热条件、地形地貌、土地利用、交通廊道、夜间灯光等不同建模参考因素对人口空间分布的影响,并分析比较了10个主要的人口统计数据空间化模型,进而对当前人口统计数据空间化研究中存在的问题做了总结,并讨论未来的研究方向.综述认为人口统计数据空间化的研究将向数据获取多源化、建模因素综合化、模拟格网精细化、模型应用实用化等方向发展;目前需要改进的问题包括:1)统一的人口数据统计标准;2)人口结构特性相关的空间化,特别是流动人口的空间分布特征识别;3)城市街区尺度的空间化方法研究;4)多源数据与人口动态信息综合中的时相匹配;5)统一的空间化指标量化方法;6)模型参数优化与精度验证方法完善.  相似文献   

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This paper describes an assessment of the enhanced geothermal system (EGS) resource base of the conterminous United States, using constructed temperature at depth maps. The temperature at depth maps were computed from 3 to 10 km, for every km. The methodology is described. Factors included are sediment thickness, thermal conductivity variations, distribution of the radioactive heat generation and surface temperature based on several geologic models of the upper 10 km of the crust. EGS systems are extended in this paper to include coproduced geothermal energy, and geopressured resources. A table is provided that summarizes the resource base estimates for all components of the EGS geothermal resource. By far, the conduction-dominated components of EGS represent the largest component of the U.S. resource. Nonetheless, the coproduced resources and geopressured resources are large and significant targets for short and intermediate term development. There is a huge resource base between the depths of 3 and 8 km, where the temperature reaches 150–250°C. Even if only 2% of the conventional EGS resource is developed, the energy recovered would be equivalent to roughly 2,500 times the annual consumption of primary energy in the U.S. in 2006. Temperatures above 150°C at those depths are more common in the active tectonic regions of the western conterminous U.S., but are not confined to those areas. In the central and eastern U.S. there are identified areas of moderate size that are of reasonable grade and probably small areas of much higher grade than predicted by this analyses. However because of the regional (the grid size is 5′ × 5′) scale of this study such potentially promising sites remain to be identified. Several possible scenarios for EGS development are discussed. The most promising and least costly may to be developments in abandoned or shut-in oil and gas fields, where the temperatures are high enough. Because thousands of wells are already drilled in those locations, the cost of producing energy from such fields could be significantly lowered. In addition many hydrocarbon fields are producing large amounts of co-produced water, which is necessary for geothermal development. Although sustainability is not addressed in this study, the resource is so large that in at least some scenarios of development the geothermal resource is sustainable for long periods of time.  相似文献   

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"Using the household-level data provided by the 5% PUMS [Public Use Microdata Sample] data from the 1990 Census, this paper reports the pattern of ethnic mixing at the household level in the U.S. and also describes the geographical patterns of different types of multiethnic households at both the state level and the PUMA [Public Use Microdata Area] level. Several of the largest metropolitan areas are also examined in greater detail. The strong dominance of whites in the process of ethnic mixing is clear, as is the expected dominance of blacks in southeastern U.S. and the dominance of Hispanics in the southwest at the state level. The PUMA-level analysis reveals local clusters of ethnic mixing that are not apparent at the state-level analysis."  相似文献   

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Reserve (or field) growth, which is an appreciation of total ultimate reserves through time, is a well-recognized phenomenon, particularly in mature petroleum provinces. The importance of forecasting reserve growth accurately in a mature petroleum province made it necessary to develop improved growth functions, and a critical review of the original Arrington method was undertaken. During a five-year (1992–1996), the original Arrington method gave 1.03% higher than the actual oil reserve growth, whereas the proposed modified method gave a value within 0.3% of the actual growth, and therefore it was accepted for the development for reserve growth models.During a five-year (1992–1996), the USGS 1995 National Assessment gave 39.3% higher oil and 33.6% lower gas than the actual growths, whereas the new model based on Modified Arrington method gave 11.9% higher oil and 29.8% lower gas than the actual growths. The new models forecast predict reserve growths of 4.2 billion barrels of oil (2.7%) and 30.2 trillion cubic feet of gas (5.4%) for the conterminous U.S. for the next five years (1997–2001).  相似文献   

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ABSTRACT

Rain-on-snow (ROS) has the potential to produce devastating floods by enhancing runoff from snowmelt. Although a common phenomenon across the eastern United States, little research has focused on ROS in this region. This study used a gridded observational snow dataset from 1960–2009 to establish a comprehensive seasonal climatology of ROS for this region. Additionally, different rain and snow thresholds were compared while considering temporal trends in ROS occurrence at four grid cells representing individual locations. Results show most ROS events occur in MAM (March-April-May). ROS events identified with rainfall >1 cm are more frequent near the east coast and events identified with >1 cm snow loss are more common in higher latitudes and/or elevations. Decreasing trends in DJF (December-January-February) ROS events were identified near the coastal areas, with increasing trends in the northern portion of the domain. Significant decreasing trends in MAM ROS are likewise present on a regional scale. Factors playing a role in snowpack depth and rainfall, such as movement of storm tracks in this region, should be considered with future work to discern mechanisms causing the changes in ROS frequency.  相似文献   

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文章基于中美人口贩运历史和现状,从国家方略、法律法规、工作机构、预警系统和受害者救助与安置回归5方面,比较了两国在打击人口贩运方面的优势和劣势。结果发现,中美人口贩运治理国家方略,均是在“以人为本、协同预防、依法打击、积极救助、妥善安置”的框架下制定的。中国更多的是针对打击国内拐卖妇女、儿童犯罪的全面性,而美国则是重点治理商业性跨国人口贩运。中国治理的特色在于自上而下的管理和自下而上的自治,一旦方略、法律法规形成,能够迅速覆盖全国执行;而美国属于联邦制国家,联邦政府与州政府是合作而非隶属关系,加之三权分立与制衡相结合的政治制度和两党制的政党制度,美国治理人口贩运问题的全国执行度、联动性还需进一步考察。最后,就中国如何应对和治理拐卖人口问题提出几点建议,具体包括:1)加大对《中国反对拐卖人口行动计划(2021—2030)》的实施力度,各地需因地制宜地明确行动措施;完善与国家法的衔接并合理吸收借鉴,持续推进针对打击人口拐卖的专门立法,增强应对能力;2)加强国际合作,重视社会建设和治理跨国、跨地域人口拐卖问题;3)细化反拐工作机构,成立专门工作组,设置专项经费,畅通建议渠道;4)构建并完善“...  相似文献   

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While much has been written about the benefits of collaborative watershed management to address nonpoint source pollution and other water quality concerns in the United States, few scholars have addressed the catalytic nature of events that generate these collective action responses. Further, because equivalent catalyst events in different communities do not always lead to collective action, it is critical to understand the interaction between a community's baseline conditions and the catalyst events that lead to collective action. This article presents a conceptual framework that illustrates the relationship between baseline conditions and events that lead to collective action. In this article a theoretical typology of catalyst events is presented that includes both intentional and nonintentional types of events. Understanding these types of catalyst events can help water quality advocates create and/or seize opportunities to nurture a collective action. This article concludes with a call for future research into catalyst events.  相似文献   

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The mean center of population of the United States is a convenient location used to summarize the population distribution of the United States and how it changes over time. As computed by the U.S. Census Bureau, the center depends on an arbitrary choice of a map projection. We feel that this location should depend only on the population distribution and not on any choices made in representing the data of the distribution. This note discusses a method for computing this location that does not depend on any choices made and describes how the results of this method differ from those of the Census Bureau.  相似文献   

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