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抛物方程法预测复杂地海环境中的电波传播 被引量:2
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作者 关晓伟 郭立新 《微波学报》 CSCD 北大核心 2023年第1期1-7,共7页
为了分析对流层环境中影响电波传播的主要因素,文章基于抛物方程模型研究了复杂地海环境下的电波传播特性,综合考虑粗糙海面Miller-Brown近似、地形遮蔽法、分段线性平移变换法等处理方法,分析了海上岛屿、沿海城市、蒸发波导、发射天... 为了分析对流层环境中影响电波传播的主要因素,文章基于抛物方程模型研究了复杂地海环境下的电波传播特性,综合考虑粗糙海面Miller-Brown近似、地形遮蔽法、分段线性平移变换法等处理方法,分析了海上岛屿、沿海城市、蒸发波导、发射天线参数、风速等因素对电波传播造成的影响。结果表明,电波传播损耗受蒸发波导、海岛高度和频率的影响较大,而远距离传播时受海面风速的影响较小,海岛的存在会使电波产生多径效应,而其遮蔽效应也会令传播损耗有所增加。此外,近海岸的地理环境同样对传播损耗的影响较大,而随着高度的增加,这种影响逐渐减小,因此,提高发射天线的高度可以有效延长探测距离。这些结果对雷达系统的设计和性能评估具有重要的指导意义。 展开更多
关键词 对流层 电波传播 抛物方程 地海环境 粗糙
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Heat transfer analysis and experimental verification of cast heat exchanger 被引量:1
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作者 俞洁 董蕾 +1 位作者 张欢 由世俊 《Journal of Central South University》 SCIE EI CAS 2012年第6期1610-1614,共5页
From the viewpoints of environmental conservation and energy efficiency,seawater-source heat pump system(SWHP) to provide district cooling and heating is applied in coastal areas.Based on the system,a heat transfer mo... From the viewpoints of environmental conservation and energy efficiency,seawater-source heat pump system(SWHP) to provide district cooling and heating is applied in coastal areas.Based on the system,a heat transfer model was established for cast heat exchanger(CHE) adopted by SWHP systems.The CHE consists of pipes immersed in the seawater and used for transferring heat between the seawater and the heat exchanger pipes of SWHP system.An experimental study was carried out to test the validity of the model.A program was developed in VB language and the effects of inlet temperature,flow rate of the secondary refrigerant and length of CHE on the results were investigated.The results of the numerical simulation are in consistence with the experiments in both winter and summer conditions.As a result,application of SWHP systems with CHE in coastal areas in China is feasible due to the favorable geographical conditions and environment. 展开更多
关键词 seawater-source heat pump cast heat exchanger mathematical model experimental verification numerical simulation
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