The angular light-scattering measurement（ALSM） method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution（ASD） simultaneousl...The angular light-scattering measurement（ALSM） method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution（ASD） simultaneously. Meanwhile, an optimized selection principle of the ALSM signals based on the sensitivity analysis and principle component analysis（PCA）is proposed to improve the accuracy of the retrieval results. The sensitivity analysis of the ALSM signals to the optical constants or characteristic parameters in the ASD is studied first to find the optimized selection region of measurement angles. Then, the PCA is adopted to select the optimized measurement angles within the optimized selection region obtained by sensitivity analysis. The investigation reveals that, compared with random selection measurement angles, the optimized selection measurement angles can provide more useful measurement information to ensure the retrieval accuracy. Finally,the aerosol optical constants and the ASDs are reconstructed simultaneously. The results show that the retrieval accuracy of refractive indices is better than that of absorption indices, while the characteristic parameters in ASDs have similar retrieval accuracy. Moreover, the retrieval accuracy in studying L-N distribution is a little better than that in studying Gamma distribution for the difference of corresponding correlation coefficient matrixes of the ALSM signals. All the results confirm that the proposed technique is an effective and reliable technique in estimating the aerosol optical constants and ASD simultaneously.展开更多
A new method is presented to improve guidance precision. This method is based on bistatic synthetic aperture radar. The illuminator works in side looking mode, providing the synthetic aperture and the receiver is disp...A new method is presented to improve guidance precision. This method is based on bistatic synthetic aperture radar. The illuminator works in side looking mode, providing the synthetic aperture and the receiver is disposed on the seeker which operates in the forward looking mode. The receiving antenna is composed of four sub-antennas and so four synthetic aperture radar （SAR） images are to be generated. Target is positioned in SAR images by image matching. The bearing and elevation of image element of target are measured by the principle of monopulse angular measurement. Theory of the proposed method is derived and simulation on bearing measurement is done. Simulation shows that the method is valid and if SNR of target＇s image is above 30 dB, the angular measuring difference is within the confines of 0.04 degree.展开更多
基金Project supported by the Jiangsu Provincial Natural Science Foundation,China(Grant Nos.BK20170800 and BK20160794)the National Natural Science Foundation of China(Grant No.51606095)
文摘The angular light-scattering measurement（ALSM） method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution（ASD） simultaneously. Meanwhile, an optimized selection principle of the ALSM signals based on the sensitivity analysis and principle component analysis（PCA）is proposed to improve the accuracy of the retrieval results. The sensitivity analysis of the ALSM signals to the optical constants or characteristic parameters in the ASD is studied first to find the optimized selection region of measurement angles. Then, the PCA is adopted to select the optimized measurement angles within the optimized selection region obtained by sensitivity analysis. The investigation reveals that, compared with random selection measurement angles, the optimized selection measurement angles can provide more useful measurement information to ensure the retrieval accuracy. Finally,the aerosol optical constants and the ASDs are reconstructed simultaneously. The results show that the retrieval accuracy of refractive indices is better than that of absorption indices, while the characteristic parameters in ASDs have similar retrieval accuracy. Moreover, the retrieval accuracy in studying L-N distribution is a little better than that in studying Gamma distribution for the difference of corresponding correlation coefficient matrixes of the ALSM signals. All the results confirm that the proposed technique is an effective and reliable technique in estimating the aerosol optical constants and ASD simultaneously.
基金the Ministerial Level Advanced Research Foundation(404050301 .4)
文摘A new method is presented to improve guidance precision. This method is based on bistatic synthetic aperture radar. The illuminator works in side looking mode, providing the synthetic aperture and the receiver is disposed on the seeker which operates in the forward looking mode. The receiving antenna is composed of four sub-antennas and so four synthetic aperture radar （SAR） images are to be generated. Target is positioned in SAR images by image matching. The bearing and elevation of image element of target are measured by the principle of monopulse angular measurement. Theory of the proposed method is derived and simulation on bearing measurement is done. Simulation shows that the method is valid and if SNR of target＇s image is above 30 dB, the angular measuring difference is within the confines of 0.04 degree.
