By considering higher order approximation to the interaural phase difference, a more general localization equation for stereo sound image with interchannel phase difference is derived. At very low frequency or low int...By considering higher order approximation to the interaural phase difference, a more general localization equation for stereo sound image with interchannel phase difference is derived. At very low frequency or low interchannel phase difference, the equation can be simplified to Makita theory. In general, image position is obviously affected by frequency.It is shown that image position varying with freqllency is the main reason for image width broadening in stereo reproduction with interchannel phase difference. And an extra interaural sound level difference caused by interchannel phase difference is the main reason for image naturalness degrading. In practice, it is necessary to reduce the interchannel phase difference,at least, to less than 60°.展开更多
We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective ang...We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective angle on the signal-to-noise ratio(SNR) is analyzed by measuring the second-order correlation of the light field based on classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector's transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.展开更多
This study presents a modified low-cost approach,which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/...This study presents a modified low-cost approach,which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/land cover change between 2000 and 2015 for the Emirate of Dubai.The approach was modified by collecting 320 training samples from QuickBird images with a spatial resolution of 0.6 m,as well as carrying out field observations,followed by the application of a 3×3 Soble filter,sieving classes,majority/minority analysis,and clump classes of the obtained classification maps.The accuracy assessment showed that the targeted 2000,2005,2010 and 2015 classification maps have 88.1252%,89.0699%,90.1225%and 96.0965%accuracy,respectively.The results showed that the built-up area increased by 233.721 km^(2)(5.81%)between 2000 and 2005 and continues to increase even up and till the present time.The assessment of changes in the periods 2000–2005 and 2010–2015 confirmed that net vegetation area losses were more pronounced from 2000 to 2005 than from 2010 to 2015,dropping from 47,618 to 40,820 km^(2),respectively.This study is aimed to assist urban planners and decision-makers,as well as research institutes.展开更多
文摘By considering higher order approximation to the interaural phase difference, a more general localization equation for stereo sound image with interchannel phase difference is derived. At very low frequency or low interchannel phase difference, the equation can be simplified to Makita theory. In general, image position is obviously affected by frequency.It is shown that image position varying with freqllency is the main reason for image width broadening in stereo reproduction with interchannel phase difference. And an extra interaural sound level difference caused by interchannel phase difference is the main reason for image naturalness degrading. In practice, it is necessary to reduce the interchannel phase difference,at least, to less than 60°.
基金National Natural Science Foundation of China(NSFC)(61372102,61571183)Natural Science Foundation of Hunan Province(2017JJ1014)
文摘We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective angle on the signal-to-noise ratio(SNR) is analyzed by measuring the second-order correlation of the light field based on classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector's transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.
文摘This study presents a modified low-cost approach,which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/land cover change between 2000 and 2015 for the Emirate of Dubai.The approach was modified by collecting 320 training samples from QuickBird images with a spatial resolution of 0.6 m,as well as carrying out field observations,followed by the application of a 3×3 Soble filter,sieving classes,majority/minority analysis,and clump classes of the obtained classification maps.The accuracy assessment showed that the targeted 2000,2005,2010 and 2015 classification maps have 88.1252%,89.0699%,90.1225%and 96.0965%accuracy,respectively.The results showed that the built-up area increased by 233.721 km^(2)(5.81%)between 2000 and 2005 and continues to increase even up and till the present time.The assessment of changes in the periods 2000–2005 and 2010–2015 confirmed that net vegetation area losses were more pronounced from 2000 to 2005 than from 2010 to 2015,dropping from 47,618 to 40,820 km^(2),respectively.This study is aimed to assist urban planners and decision-makers,as well as research institutes.
