Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-10 Cooperative journals: 《干旱区研究》
Abstract： 采用2000—2015年MODIS1M NDVI数据计算黄河上游年最大植被覆盖度 (FVC)，了解空间分布状况及变化特征；同时，采用了一种基于统计学原理的地理探测器模型，考虑非气候类环境因素、气候类环境因素和人类活动因素，使用相应的代理变量对黄河上游FVC空间分布的影响因素做定量研究。研究表明：① 黄河上游FVC总体上以改善为主，空间分布特征变化不大；② 单因子方面，降水量(q值0.669)是该地区FVC空间分布的主要影响因素，其他因子的影响作用存在区域差异；③ 降水分别和土壤类型、土地利用方式的交互作用(q值0.777、0.775)对研究区FVC空间分布起主导作用，土壤类型和土地利用的影响作用在一定高程、降水条件下才得以体现；④ 总体上，气候类环境因素>非气候类环境因素>人类活动因素，人类活动在与降水等环境因子的共同作用能够更充分地解释FVC空间分布；⑤ 对研究区的生态恢复应重点放在降水的充分利用和土地利用方式改进等方面。
Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：针对卫星有效载荷数传数据传输速度快、实时处理难等特点，提出一种面向有效载荷高速数据流的实时数据处理方法。该方法借鉴MapReduce的多线程并行模式，采用hash算法与归并排序算法相结合的方式，提高数据处理吞吐率，实现实时处理；采用基于XTCE(XML Telemetry & Command Exchange)数据模型的参数解析算法，实现通用性。实验表明该方法能够满足有效载荷对数据处理的实时性和正确性的要求。
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： For deep space communication paths close to the sun causing solar scintillation of radio waves and increasing bit error rate(BER),the approach of choosing the signal bandwidth in the non-frequency selective and slow fading channel with maximum time was proposed.The deep space communication channel model was built based on Rician fading channel model.The statistical characteristics of the amplitude, the coherence time and the coherence bandwidth of the channel were used.The difference among solar scintillation,mobile multipath and ionosphere scintillation was compared. Based on the change of the coherence time and coherence bandwidth with solar elongation angle,the time-selective and frequency-selective characters were determined. Simulation results show that at different little solar elongation angle,especially the small one,the BER of the signal bandwidth chosen by the proposed approach is better than the BER of other signal bandwidth.
Peer Review Status:Awaiting Review
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