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41.
Assessing the landscape context and conversion risk of protected areas using satellite data products
Leona K. Svancara J. Michael Scott Anna B. Pidgorna 《Remote sensing of environment》2009,113(7):1357-227
Since the establishment of the first national park (Yellowstone National Park in 1872) and the first wildlife refuge (Pelican Island in 1903), dramatic changes have occurred in both ecological and cultural landscapes across the U.S. The ability of these protected areas to maintain current levels of biodiversity depend, at least in part, on the integrity of the surrounding landscape. Our objective was to quantify and compare the extent and pattern of natural land cover, risk of conversion, and relationships with demographic and economic variables in counties near National Park Service units and U.S. Fish and Wildlife Service refuges with those counties distant from either type of protected area in the coterminous United States. Our results indicate that landscapes in counties within 10 km of both parks and refuges and those within 10 km of just parks were more natural, more intact, and more protected than those in counties within 10 km of just refuges and counties greater than 10 km from either protected area system. However, they also had greater human population density and change in population, indicating potential conversion risk since the percent of landscape protected averaged < 5% in both groups and human population dynamics are primary drivers of change in many landscapes. Conversion outweighed protection by at least two times (Conservation Risk Index > 2) in 76% of counties near both parks and refuges, 81% of counties near just parks, 91% of counties near just refuges, and 93% of distant counties. Thirteen percent of counties in the coterminous U.S. had moderate to high amounts of natural land cover (> 60%), low protection (< 20%), and the greatest change in population (> 20%). Although these areas are not the most critically endangered, they represent the greatest conservation opportunity, need, and urgency. Our approach is based on national level metrics that are simple, general, informative, and can be understood by broad audiences and by policy makers and managers to assess the health of lands surrounding parks and refuges. Regular monitoring of these metrics with satellite data products in counties surrounding protected areas provides a consistent, national level assessment of management opportunities and potentially adverse changes on adjacent lands. 相似文献
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介绍一种接口电路,可采集符合现场总线标准的直流电信号。因此,对标准信号设计采休电路具有普遍意义。文中对采集板的硬件设计和软件进行了较详细介绍。 相似文献
43.
基于Windows 9x/2000/NT平台汉字输入法的设计 总被引:14,自引:0,他引:14
本文首先分析了在中文(简体/繁体)Windows9x/2000/NT中,汉字输入法的组成和设计思想,在此基础上介绍了Windows9x/2000/NT平台下汉字输入法的开发环境、数据结构和一些关键技术的实现手段。 相似文献
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P. Campestrini E.P.M. van WestingA. Hovestad J.H.W. de Wit 《Electrochimica acta》2002,47(7):1097-1113
The parameters of the chromate bath, like temperature, pH, and fluoride content, strongly affect the morphology and chemical composition of the chromate conversion coating and as a consequence have a large influence on its corrosion performance. In this paper, electrochemical impedance spectroscopy (EIS) was used in combination with other techniques to investigate the role played by the pH of the chromate bath on the properties of the chromate film formed on Alclad 2024 aluminium alloy. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectroscopic ellipsometry (SE) have shown the formation of a thicker and less dense chromate layer when the pH of the chromate bath is changed from 2.4 to 1.2. The analysis of the EIS spectra have highlighted that this change in pH leads to the formation of more protective and more resistant chromate corrosion products (CCP) inside the defects of the chromate film. When a thin, dense and protective layer of CCP is formed in the defects, the corrosion behaviour of the chromate conversion coating improves for two main reason: (a) further attack of the defects is avoided or delayed; (b) the change in volume caused by the formation of the CCP is limited resulting in a low level of stress in the film, which as a consequence is not detached from the aluminium substrate. 相似文献
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用NaI(Tl)探测器测量γ辐射场剂量特性的加权积分法研究 总被引:3,自引:0,他引:3
辐射场剂量特性的测量可以通过剂量率仪或谱 剂量转换的方法来实现。其中一种谱 剂量转换的方法是通过一个G(E)函数 ,把测得的结果直接换算成剂量而不需解谱。本文采用这种方法 ,对一个75mm× 75mm的NaI(Tl)探测器的能谱特性进行测量与分析 ,算出了该晶体的G(E)函数值及估计的误差 ,并用此方法与高气压电离室作了比对测量 相似文献
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dBASEX、FoxBASE、FoxPro等XBASE数据库改造升级时,XBASE数据库DBF表文件向Oracle、SQLSever等数据库加载升级有各种不同的方法,但对于存储在FPT备注文件中的图像和WAV音频等多媒体信息数据的转换则没有好的解决办法。论文分析了各个版本XBASE数据库文件、图像和WAV音频的存储结构,提出了面向文件的XBASE数据库多媒体信息导出转换的自动批处理方法,提高了数据库转换工作的效率,解决了无法转换XBASE备注文件中多媒体数据的问题,该方法具有很强的可操作性和实用性。 相似文献