A conditional boost-phase trajectory estimation method based on ballistic missile （BM） information database and classification is developed to estimate and predict boos-phase BM trajectory. The main uncertain factor...A conditional boost-phase trajectory estimation method based on ballistic missile （BM） information database and classification is developed to estimate and predict boos-phase BM trajectory. The main uncertain factors to describe BM dynamics equation are reduced to the control law of trajectory pitch angle in boost-phase. After the BM mass at the beginning of estimation, the BM attack angle and the modification of engine thrust denoting BM acceleration are modeled reasonably, the boost-phase BM trajectory estimation with ground based radar is well realized. The validity of this estimation method is testified by computer simulation with a typical example.展开更多
In order to explain theoretically the observational biases of reflectivity and structure of precipitation systems by TRMM Precipitation Radar (TRMM PR) and ground-based radar,the effects of wavelengths,incident direct...In order to explain theoretically the observational biases of reflectivity and structure of precipitation systems by TRMM Precipitation Radar (TRMM PR) and ground-based radar,the effects of wavelengths,incident direction of radar waves and radar beam width on the reflectivity observation are simulated.The results show that the error due to the different wavelength and incident direction of radar wave is within 2.0 dB,TRMM PR can observe a larger reflectivity than ground-based radar in echo center.TRMM PR smoothes the cloud structure,overestimates and underestimates reflectivity by 3-5 dB in strong and week echo areas,respectively.Beam width and long distance from TRMM PR to target cause it to overestimate the large echo area and area integrated rainfall amount,and to underestimate the averaged refleetivity.The theoretical results above can only explain part of observational facts,meaning that the comparison of observation results between TRMM PR and ground-based radar is complicated,the attenuation of radar wave within precipitation area is the main factor to affect the observed result.展开更多
Much work has been done on radar calibration in recent years since the inversion and classification algorithms rely heavily on the precision of measured radar data. In order to take the quantitative backscattering mea...Much work has been done on radar calibration in recent years since the inversion and classification algorithms rely heavily on the precision of measured radar data. In order to take the quantitative backscattering measurement, external calibration should be carried out At precent, one of the common calibration methods is the point-target method. However,展开更多
提出一种地基真孔径雷达(Ground-Based Real Aperture Radar,GB-RAR)变形信息估计方法,将该方法应用于上海某地铁线路盾构隧道下穿E大桥的安全监测与分析。基于GB-RAR数据进行分析推导,得到桥梁的沉降变形时间序列,并通过水准测量进行...提出一种地基真孔径雷达(Ground-Based Real Aperture Radar,GB-RAR)变形信息估计方法,将该方法应用于上海某地铁线路盾构隧道下穿E大桥的安全监测与分析。基于GB-RAR数据进行分析推导,得到桥梁的沉降变形时间序列,并通过水准测量进行了验证,精度优于0.27 mm。通过功率谱分析和最大似然估计,去除彩色噪声比,不考虑彩色噪声影响的变形监测信息更准确,与水准测量结果更加吻合。研究结果表明,该方法在本次工作中具有可靠性和有效性,桥梁在监测期内稳定、安全。展开更多
文摘A conditional boost-phase trajectory estimation method based on ballistic missile （BM） information database and classification is developed to estimate and predict boos-phase BM trajectory. The main uncertain factors to describe BM dynamics equation are reduced to the control law of trajectory pitch angle in boost-phase. After the BM mass at the beginning of estimation, the BM attack angle and the modification of engine thrust denoting BM acceleration are modeled reasonably, the boost-phase BM trajectory estimation with ground based radar is well realized. The validity of this estimation method is testified by computer simulation with a typical example.
基金the Project of National Fundamental Research Planning"Research on the formation mechanism and the prediction theory of hazardous weather over China"(G1998040909)Doctoral Start-up Foundation Project in Chinese Academy of Meteorological Sciences
文摘In order to explain theoretically the observational biases of reflectivity and structure of precipitation systems by TRMM Precipitation Radar (TRMM PR) and ground-based radar,the effects of wavelengths,incident direction of radar waves and radar beam width on the reflectivity observation are simulated.The results show that the error due to the different wavelength and incident direction of radar wave is within 2.0 dB,TRMM PR can observe a larger reflectivity than ground-based radar in echo center.TRMM PR smoothes the cloud structure,overestimates and underestimates reflectivity by 3-5 dB in strong and week echo areas,respectively.Beam width and long distance from TRMM PR to target cause it to overestimate the large echo area and area integrated rainfall amount,and to underestimate the averaged refleetivity.The theoretical results above can only explain part of observational facts,meaning that the comparison of observation results between TRMM PR and ground-based radar is complicated,the attenuation of radar wave within precipitation area is the main factor to affect the observed result.
基金the National Natural Science Foundation of China, and CAS President Foundation.
文摘Much work has been done on radar calibration in recent years since the inversion and classification algorithms rely heavily on the precision of measured radar data. In order to take the quantitative backscattering measurement, external calibration should be carried out At precent, one of the common calibration methods is the point-target method. However,
文摘提出一种地基真孔径雷达(Ground-Based Real Aperture Radar,GB-RAR)变形信息估计方法,将该方法应用于上海某地铁线路盾构隧道下穿E大桥的安全监测与分析。基于GB-RAR数据进行分析推导,得到桥梁的沉降变形时间序列,并通过水准测量进行了验证,精度优于0.27 mm。通过功率谱分析和最大似然估计,去除彩色噪声比,不考虑彩色噪声影响的变形监测信息更准确,与水准测量结果更加吻合。研究结果表明,该方法在本次工作中具有可靠性和有效性,桥梁在监测期内稳定、安全。
