In the spaceborne/airborne forward-looking bistatic syn- thetic aperture radar （SA-FBSAR）, due to the system platforms＇ remarkable velocity difference and the forward-looking mode, the range cell migration （RCM） ...In the spaceborne/airborne forward-looking bistatic syn- thetic aperture radar （SA-FBSAR）, due to the system platforms＇ remarkable velocity difference and the forward-looking mode, the range cell migration （RCM） not only depends on the target＇s two- dimensional location, but also varies with the range location non- linearly. And the nonlinearity is not just the slight deviation from the linear part, but exhibits evident nonlinear departure in the RCM trajectory. If the RCM is not properly corrected, nonlinear image distortions would occur. Based on the RCM model, a modified two-step RCM compensation （RCMC） method for SA-FBSAR is proposed. In this method, firstly the azimuth-dependent RCM is compensated by the scaling Fourier transform and the phase multi- plication. And then the range-dependent RCM is removed through interpolation. The effectiveness of the proposed RCMC method is verified by the simulation results of both point scatterers and area targets.展开更多
以提高瓦斯抽采效果为目标,某矿Ⅲ4423工作面为研究对象,采用理论分析、数值模拟、现场试验等研究方法,研究了顶板高位钻孔条件下瓦斯抽采的主要技术参数,数值模拟出高位钻孔抽采瓦斯前采空区的瓦斯分布情况与运移规律,以及负压分别为8...以提高瓦斯抽采效果为目标,某矿Ⅲ4423工作面为研究对象,采用理论分析、数值模拟、现场试验等研究方法,研究了顶板高位钻孔条件下瓦斯抽采的主要技术参数,数值模拟出高位钻孔抽采瓦斯前采空区的瓦斯分布情况与运移规律,以及负压分别为8、10 k Pa时的高位钻孔瓦斯抽采效果。依据瓦斯流动"O"型圈理论与FLUENT数值模拟分析,优化设计高位钻孔抽采瓦斯工艺参数并进行现场试验。结果表明:当高位钻孔抽采负压为8 k Pa、终孔位置调整到采空区裂隙带回风巷侧15~35 m范围内时,高位钻孔抽采瓦斯效果最佳,采空区内瓦斯最高浓度明显降低,单个钻场最大抽采瓦斯量为19 821.74 m^3,钻孔瓦斯浓度稳定在20%~30%之间,最大值达到50%,实现了工作面有效治理瓦斯和安全生产的目标。展开更多
基金supported by the National Natural Science Foundation of China (61102143)the Fundamentl Research Funds for the Central Universities (ZYGX2011x003)
文摘In the spaceborne/airborne forward-looking bistatic syn- thetic aperture radar （SA-FBSAR）, due to the system platforms＇ remarkable velocity difference and the forward-looking mode, the range cell migration （RCM） not only depends on the target＇s two- dimensional location, but also varies with the range location non- linearly. And the nonlinearity is not just the slight deviation from the linear part, but exhibits evident nonlinear departure in the RCM trajectory. If the RCM is not properly corrected, nonlinear image distortions would occur. Based on the RCM model, a modified two-step RCM compensation （RCMC） method for SA-FBSAR is proposed. In this method, firstly the azimuth-dependent RCM is compensated by the scaling Fourier transform and the phase multi- plication. And then the range-dependent RCM is removed through interpolation. The effectiveness of the proposed RCMC method is verified by the simulation results of both point scatterers and area targets.
文摘发展风电、光电等可再生能源是国家战略需求.为了适配风、光等可再生能源波动性强的特征,储能系统的研究至关重要.以二氧化碳(CO_(2))为工质的热泵发电储能系统在能量密度、环境适应性和投资等方面具备优势,是备受关注的新型储能技术.本文基于提出的CO_(2)热泵发电储能系统,重点获取系统充注、热泵系统启动运行、热泵发电系统切换、发电系统启动运行的全工作阶段响应特性,提出了系统内部CO_(2)工质的质量评估方法,考察CO_(2)工质在压力容器、换热部件及管路中随全工作阶段的动态分布及容量迁移量化规律.结果表明,热泵系统在启动准备阶段其闪蒸罐及蒸发器占据CO_(2)总容量的61.2%,随着热泵系统运行,闪蒸罐内液态CO_(2)迁出,蒸发器及冷却器容量均增加,闪蒸罐气液容量分布主要受压力影响而冷却器的容量增长幅度则主要取决于运行温度.切换及发电系统运行阶段,缓存罐承担主要容量迁移,切换完成时增加4600.6 kg、运行时则降低1863.6 kg.
文摘以提高瓦斯抽采效果为目标,某矿Ⅲ4423工作面为研究对象,采用理论分析、数值模拟、现场试验等研究方法,研究了顶板高位钻孔条件下瓦斯抽采的主要技术参数,数值模拟出高位钻孔抽采瓦斯前采空区的瓦斯分布情况与运移规律,以及负压分别为8、10 k Pa时的高位钻孔瓦斯抽采效果。依据瓦斯流动"O"型圈理论与FLUENT数值模拟分析,优化设计高位钻孔抽采瓦斯工艺参数并进行现场试验。结果表明:当高位钻孔抽采负压为8 k Pa、终孔位置调整到采空区裂隙带回风巷侧15~35 m范围内时,高位钻孔抽采瓦斯效果最佳,采空区内瓦斯最高浓度明显降低,单个钻场最大抽采瓦斯量为19 821.74 m^3,钻孔瓦斯浓度稳定在20%~30%之间,最大值达到50%,实现了工作面有效治理瓦斯和安全生产的目标。
