Gaofen-3-02(GF3-02)is the first C-band synthetic aperture radar(SAR)satellite with terrain observation with progressive scans of SAR(TOPSAR)imaging mode in China,which plays an essential role in marine environment mon...Gaofen-3-02(GF3-02)is the first C-band synthetic aperture radar(SAR)satellite with terrain observation with progressive scans of SAR(TOPSAR)imaging mode in China,which plays an essential role in marine environment monitoring.Given the weak scattering characteristics of the ocean,the system thermal noise superimposed on SAR images has significant interference,especially in cross-polarization channels.Noise-Equivalent Sigma-Zero(NESZ)is a measure of the sensitivity of the radar to areas of low backscatter.The NESZ is defined to be the scattering cross-section coefficient of an area which contributes a mean level in the image equal to the signal-independent additive noise level.For TOPSAR,NESZ exhibits the shape of the SAR scanning gain curve in the azimuth and the shape of the antenna pattern in the range.Therefore,the accurate measurement of NESZ plays a vital role in the application of spaceborne SAR sea surface cross-polarization data.This paper proposes a theoretical calculation method for the NESZ curve in GF3-02 TOPSAR mode based on SAR noise inner calibration data and the imaging algorithm.A method for correcting the error existing in the theoretical curve of NESZ is also proposed according to the relationship between sea surface backscattering and wind speed and the same characteristics of target scattering in the overlapping area of adjacent sub-swaths.According to assessment with wide-swath TOPSAR cross-polarization data,the GF3-02 TOPSAR mode has a very low thermal noise level,which is better than−33 dB at the edge of each beam,and controlled below−38 dB at the center of the beam.The two-dimensional reference curves of the NESZ of each beam are provided to the GF3-02 TOPSAR users.After discussing the relationship between normalized radar cross section(NRCS)and wind speed,we provide a formula for NRCS related to wind speed and radar incidence angle.Compared with the NRCS derived from this formula and the NESZ-subtracted NRCS of SAR images,the bias is−0.0048 dB,the Root Mean Square Error is 1.671 dB and the correlation coefficient is 0.939.展开更多
[目的]梳理健康信念模式研究脉络,以呈现其学科发展和研究热点,为我国健康信念模式的进一步研究提供参考。[方法]在Web of Science数据库中,以"health belief model"为主题词进行检索,检索时间为自建库至2017年1月,并对所得...[目的]梳理健康信念模式研究脉络,以呈现其学科发展和研究热点,为我国健康信念模式的进一步研究提供参考。[方法]在Web of Science数据库中,以"health belief model"为主题词进行检索,检索时间为自建库至2017年1月,并对所得文献数据使用CiteSpaceⅣ进行可视化分析。[结果]共检索得到609条文献记录,发文数量总体呈逐年上升趋势。现阶段研究热点主要集中于乳腺自检健康教育、健康信念、健康信念模式、基于健康信念模式的乳腺癌信念及注册前学位课程教育相关研究;更多的研究焦点由原来描述病人的护理问题转变为通过试验来探讨基于健康信念模式进行干预的效果。[结论]健康信念模式主要研究热点聚焦于提高健康行为益处和提高自我效能方面,未来应着眼于其在降低预防性障碍、改进文化适用性和健康信念模式方面的研究。展开更多
基金The National Natural Science Foundation of China under contract No.41976169.
文摘Gaofen-3-02(GF3-02)is the first C-band synthetic aperture radar(SAR)satellite with terrain observation with progressive scans of SAR(TOPSAR)imaging mode in China,which plays an essential role in marine environment monitoring.Given the weak scattering characteristics of the ocean,the system thermal noise superimposed on SAR images has significant interference,especially in cross-polarization channels.Noise-Equivalent Sigma-Zero(NESZ)is a measure of the sensitivity of the radar to areas of low backscatter.The NESZ is defined to be the scattering cross-section coefficient of an area which contributes a mean level in the image equal to the signal-independent additive noise level.For TOPSAR,NESZ exhibits the shape of the SAR scanning gain curve in the azimuth and the shape of the antenna pattern in the range.Therefore,the accurate measurement of NESZ plays a vital role in the application of spaceborne SAR sea surface cross-polarization data.This paper proposes a theoretical calculation method for the NESZ curve in GF3-02 TOPSAR mode based on SAR noise inner calibration data and the imaging algorithm.A method for correcting the error existing in the theoretical curve of NESZ is also proposed according to the relationship between sea surface backscattering and wind speed and the same characteristics of target scattering in the overlapping area of adjacent sub-swaths.According to assessment with wide-swath TOPSAR cross-polarization data,the GF3-02 TOPSAR mode has a very low thermal noise level,which is better than−33 dB at the edge of each beam,and controlled below−38 dB at the center of the beam.The two-dimensional reference curves of the NESZ of each beam are provided to the GF3-02 TOPSAR users.After discussing the relationship between normalized radar cross section(NRCS)and wind speed,we provide a formula for NRCS related to wind speed and radar incidence angle.Compared with the NRCS derived from this formula and the NESZ-subtracted NRCS of SAR images,the bias is−0.0048 dB,the Root Mean Square Error is 1.671 dB and the correlation coefficient is 0.939.
文摘[目的]梳理健康信念模式研究脉络,以呈现其学科发展和研究热点,为我国健康信念模式的进一步研究提供参考。[方法]在Web of Science数据库中,以"health belief model"为主题词进行检索,检索时间为自建库至2017年1月,并对所得文献数据使用CiteSpaceⅣ进行可视化分析。[结果]共检索得到609条文献记录,发文数量总体呈逐年上升趋势。现阶段研究热点主要集中于乳腺自检健康教育、健康信念、健康信念模式、基于健康信念模式的乳腺癌信念及注册前学位课程教育相关研究;更多的研究焦点由原来描述病人的护理问题转变为通过试验来探讨基于健康信念模式进行干预的效果。[结论]健康信念模式主要研究热点聚焦于提高健康行为益处和提高自我效能方面,未来应着眼于其在降低预防性障碍、改进文化适用性和健康信念模式方面的研究。
