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地带性覆盖星座通用优化设计方法研究 被引量:4
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作者 连全斌 张乃通 张中兆 《高技术通讯》 EI CAS CSCD 2001年第5期54-59,共6页
由于在地带性多重覆盖、混合星座覆盖等复杂的覆盖要求面前 ,现有的星座设计方法难以适用。针对这一问题 ,在基于对星座覆盖性判断的基础上 ,提出了一种适用于各种不同要求的地带性覆盖 (包括全球覆盖 )星座通用优化设计方法。
关键词 卫星 星座设计 覆盖 地带覆盖 多重覆盖 优化设计
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双基站星座覆盖性能分析及星座设计 被引量:1
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作者 张娟 和兴锁 +2 位作者 邓峰岩 李亮 张烈霞 《西北工业大学学报》 EI CAS CSCD 北大核心 2004年第2期239-242,共4页
在双基站理论研究基础上 ,首先给出了星座对双基站覆盖性能分析时的 3个定理并予以证明 ,然后分析了对 0°~ 5 5°纬度带覆盖时的一种双基站星座设计方法。该方法首先判断在进行星座设计时是否需要考虑星座对空间站的覆盖性能 ... 在双基站理论研究基础上 ,首先给出了星座对双基站覆盖性能分析时的 3个定理并予以证明 ,然后分析了对 0°~ 5 5°纬度带覆盖时的一种双基站星座设计方法。该方法首先判断在进行星座设计时是否需要考虑星座对空间站的覆盖性能 ,然后用本文提供的方法大概确定满足覆盖要求的星座构型 ,再根据点覆盖数值仿真方法计算具体星座参数 ,最后检验星座对空间站的覆盖性能。 展开更多
关键词 地带覆盖 双基站 星座设计
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Geographical Variants of the Siberian Alpine Vegetation for the "Circum-Boreal Vegetation Map"
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作者 Galina N. Ogureeva 《Journal of Life Sciences》 2013年第6期643-652,共10页
The vegetation cover in highlands is rather peculiar and complicated in its structure. The experience gained in mapping of alpine vegetation shows that the schematic small-scale maps reflect only the very common featu... The vegetation cover in highlands is rather peculiar and complicated in its structure. The experience gained in mapping of alpine vegetation shows that the schematic small-scale maps reflect only the very common features. In boreal forest mountains of Siberia there are four systems of alpine vegetation including alpine-meadow, goltsy-tundra, island near the Pacific Ocean and tundra-steppe ones. Every system is represented by several geographical variants, characterized by regional phytogeographical peculiar features of this vegetation. The geographical variant includes a number of altitudinal belts (zones), each of them has its floristic peculiarities and complexes of plant formations (for instance, Altai-Sayan variant composes of subalpine-alpine-subnival-nival belts). Such geographical variants of alpine vegetation may be indicated as chorological units on a new Circum-Boreal Vegetation Map. Under discussion is the possible use of ecological-geographical approach to reflect the alpine vegetation as chorological (structural) units of the vegetation cover being exemplified by high mountains of the Siberia. This map may be more informative in terms of regional peculiarities in alpine vegetation within the boreal biome. 展开更多
关键词 BIODIVERSITY mapping high mountain (alpine) vegetation altitudinal zonality type.
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Changes in the Ecological Characteristics of Key Biodiversity Areas in the BRI Region 被引量:2
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作者 WANG Boyu YAN Huimin +1 位作者 FENG Zhiming YANG Yanzhao 《Journal of Resources and Ecology》 CSCD 2022年第2期328-337,共10页
Key Biodiversity Areas(KBAs)are ecological conservation priorities proposed by IUCN and widely recognized by most countries.Evaluating the changes in the ecological characteristics in KBAs is important for biodiversit... Key Biodiversity Areas(KBAs)are ecological conservation priorities proposed by IUCN and widely recognized by most countries.Evaluating the changes in the ecological characteristics in KBAs is important for biodiversity conservation and the construction of Protected Areas(PAs).There are various ecosystem types in the Belt and Road Initiative(BRI)region,which has an extremely high value of biodiversity conservation,and the KBAs should be the prime targets of ecological protection efforts.Using the data of land cover,NDVI and Nighttime Light(NTL),we analyzed the ecological conditions of the KBAs in the BRI region,and their temporal and spatial variations,from the perspectives of vegetation coverage and human activities.The conclusions are:(1)There is generally no significant difference in the land cover of the KBAs,among which forest,wilderness and grassland are the main types;(2)The NDVI of the KBAs showed an increase,indicating that the vegetation was gradually improving,while a few KBAs presenting vegetation degradation were mainly distributed in the Indochina Peninsula,Qinghai-Tibet Plateau and Central and Western Asia;and(3)The NTL in the KBAs was very low,indicating that the human pressure on the natural ecosystems was limited,and only a few KBAs distributed in Central and Eastern Europe,India,and the Indochina Peninsula have high human activity intensity which also showed an increase.This study emphasizes that we should make full use of the biome succession law,and limit the interference of human activities on natural ecosystems for ecological protection of the KBAs,so as to continuously make new breakthroughs in the construction of Protected Areas(PA)in the BRI region. 展开更多
关键词 Biodiversity Areas(KBAs) the Belt and Road Initiative(BRI) land cover vegetation coverage human activities temporal and spatial variations
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