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981.
《The Professional geographer》2013,65(3):296-297
Edward Jarvis in 1850 first demonstrated that admission rates to mental hospitals decrease with increasing residential distance, a relationship known today as “Jarvis's Law.” His original data are presented, mapped, and examined by regression analysis to better understand spatial and temporal patterns of mid-19th century mental hospital utilization. Distance substantially affected admission rates to a radius of about 60 miles from the institution in Massachusetts; and there was strong distance decay in the other states examined. For all twelve states, there was a positive association between age of the hospitals and admission rates, which also decreased with increasing residential distance. 相似文献
982.
Ecosystem services (ES) and ecosystem services assessment (ESA) have become common parlance in the environmental field. Scientists, policy-makers and activists have promoted the ES approach as a means of conveying the extent of threats to natural ecosystems with the goal of crafting socially acceptable and effective policy to address ecological threats and biodiversity conservation. Yet there are some significant challenges to wide acceptance of the ES approach which hinder its absorption into the mainstream geography literature. This paper reviews the historical development of the ES approach focusing on its relevance to applied geography at different stages of its development, describes the present state-of-the-art of ES, and synthesizes the results from several seminal papers and reports. I posit that there are two major stumbling blocks: 1) the difficulty of simplifying complexities between services so that statutory planning processes can incorporate the approach, and 2) the lack of cross-landscape assessment methods and examples. If we focus on the most immediately surmountable challenges to the ES approach much progress could be made in a short time. The subsequent and final substantive section of this review summaries these challenges and offers some suggestions for moving forward. 相似文献
983.
《International Journal of Digital Earth》2013,6(5):373-390
Security has recently become a major concern in distributed geo-infrastructures for spatial data provision. Thus, a lightweight approach for securing distributed low-power environments such as geo-sensor networks is needed. The first part of this article presents a survey of current security mechanisms for authentication and authorisation. Based on this survey, a lightweight and scalable token-based security infrastructure was developed, which is tailored for use in distributed geo-web service infrastructures. The developed security framework comprises dedicated components for authentication, rule-based authorisation and optimised storage and administration of access rules. For validation purposes, a prototypical implementation of the approach has been created. 相似文献
984.
《International Journal of Digital Earth》2013,6(1):68-87
China is one of the most disaster-prone countries in the world. Currently, the disaster prevention and relief mechanism in China is mainly based on single disaster types and is implemented by different ministries and divisions in single administrative regions. Subsequently, the available resources, including data, services, materials, and human resources, cannot be shared and used effectively. Based on the idea of an observation system of systems and a business system of systems, this paper presents an integrated framework for a Chinese National Disaster Reduction System of Systems (CNDRSS) to address this issue. The CNDRSS framework aims to achieve data sharing and collaboration among different disaster-related ministries/institutions by providing one-stop services for all phases of disaster management and linking together existing and planned disaster-related business systems and observation systems. The key technologies use federated databases and a web service to integrate multiple disaster management systems among different ministries/institutions and a sensor web to integrate airborne, space-borne, and in-situ observations through the web service. These event-driven focused-services connecting the various observations, processing, and mapping processes can meet the requirements for complex disaster-chain systems. 相似文献
985.
《自然地理学》2013,34(6):499-512
Over the past 30 years, conservationists have sought ways to assess the quality of coverage provided by protected areas and to guide future site selection. One scheme among these addresses the degree to which areas protected for environmental conservation are representative of the ecological regions of a specified area. This has already been attempted at the scale of countries and regions. With the recent publication of the World Database of Protected Areas, quantitative analysis of representativeness at the global scale is finally feasible. We use GIS technology to overlay a map of ecological regions with a map of protected areas in order to identify biomes and geographic realms that are "under-represented" and "well represented" by protected areas. The results confirm an overemphasis on marginal land and dramatic landscapes, and the relative neglect of biomes with strong, alternative economic uses. Smaller biomes are typically better protected, as are those that have been targeted by conservation campaigns. Industrialized lifestyles and population pressure also appear to act as stimuli to protection. Our discussion suggests that analyses of patterns of representation are critical, but "over-representing" certain ecosystems—particularly those that contain high levels of biodiversity or are most threatened—should not be discounted as a conservation strategy. 相似文献
986.
987.
为了减少对GPS提供的高精度授时服务的依赖,建设拥有自主知识产权的且具有投入成本低、精度高的授时系统。提出了一种利用地面高稳定度原子钟作为时频基准,通过通信卫星转发实现卫星广播授时的新方法。详细研究了利用地面高稳定度原子钟和通信卫星组成的导航星座进行多星授时、单星授时的原理和测量方法,分析研究了影响授时精度的原因。由于转发式卫星授时系统的时频基准源稳定度高,其测距精度也会相应的提高。只要精确扣除时延误差,同样可以实现高精度授时。粗码的授时精度可达20ns以内,短精码的授时精度可达10ns左右。总之该系统具有组建灵活简便、应用面广等优势和特色。 相似文献
988.
AbstractIntegrating local and Indigenous knowledge into land-use planning and the assessment of ecosystems services requires reliable, quantitative data. We tested two approaches to obtain such data by quantifying farmer opinion of different land-covers in Eastern Panama using (1) the analytic hierarchy process (AHP) and (2) a simpler ranking and scoring technique. Both methods produce a set of numerical values reflecting the ability of land-covers to deliver ecological and socio-economic criteria. We present our experience with both methods and offer recommendations for researchers looking to quantify landholder opinion. The AHP survey was relatively long (on average it took 19?min to complete per criterion) and we faced problems with inconsistent responses. In contrast, the ranking and scoring method was much quicker (only 3?min per criterion) and therefore may be more suitable for gathering more data from a larger number of farmers. 相似文献
989.
Julia Jones Auro Almeida Felipe Cisneros Andres Iroumé Esteban Jobbágy Antonio Lara Walter de Paula Lima Christian Little Carlos Llerena Luis Silveira Juan Camilo Villegas 《水文研究》2017,31(5):972-980
South America is experiencing rapid change in forest cover, of both native and planted forest. Forest cover loss is primarily attributable to fire, logging, and conversion of native forest to agriculture, pasture, and forest plantations, and types of change vary within and among the many diverse types of forests in South America. Major changes in forest cover and growing policy concerns underscore an urgent need for research on sustainable forest management and water ecosystem services in South America. Differences in land ownership and management objectives create trade‐offs between wood production and water ecosystem services from forests. Work is needed to quantify how forest change and management affect ecosystem services, such as wood production versus water provision. Current scientific understanding of forest management effects on water ecosystem services in South America has important limitations, including a scarcity of long‐term records and few long‐term integrated watershed studies. Industry, government, universities, and local communities should collaborate on integrated applied studies of forests and water. Data archiving and publically available data are required. The creation of national networks and a multi‐country South America network to identify and implement common water research protocols, share results, and explore their implications would promote common and well‐supported policies. Hydrologists working in South America are well placed to tackle the challenges and opportunities for collaborative research that will maintain the intrinsic values and water ecosystem services provided by South America's forests. 相似文献
990.
Forest ecosystem services and their values in Beijing 总被引:5,自引:3,他引:2
Gaodi Xie Wenhua Li Yu Xiao Biao Zhang Chunxia Lu Kai An Jixing Wang Kang Xu Jinzeng Wang 《中国地理科学(英文版)》2010,20(1):51-58
As the most important ecosystem in Beijing, the forest supports a lot of ecosystem services to local and around communities, which plays a key role in the maintenance of urban ecological security.However, the valuation on the forest ecosystem services based on regional scale could not provide precise and reasonable values for forestry sector management.In this study, we estimated the magnitudes and economic values of the forest ecosystem services in Beijing at sublot level.The economic value of forest ecosystem services in Beijing was estimated to be 19 339.71×10 6 yuan(RMB) in 2004.Among all the ecosystem services indicators we estimated in this study, only fruit, timber and part of the recreation(which only include the tourism income from the forest parks and scenic areas, but not include that from other forest types) were measured in the social economic system.As estimated in this study, more than 82.19% of the economic value of forest ecosystem services could not be measured in the socio-economic statistical system.The importance of forest ecosystem services in Beijing to human welfare was underestimated by the socio-economic system.Therefore, the policies about the eco-compensation of forest ecosystem services should be established to maintain the sustainable supply of the forest ecosystem services in Beijing. 相似文献