The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu- merical modeling. An approximate analytical solution of horizontal-longitudinal correlation coefficie...The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu- merical modeling. An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method. Combining the characteristic of Lloyd＇s mirror interference pattern, the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed. The theoretical pre- diction agrees well with the numerical results. Experimental results confirm the validity of analytical solution. Finally, the applicability of the analytical solution is summarized. The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.展开更多
A theoretical model of ambient sea noise including surface noise sources and stratified medium ocean is discussed. The noise sources are assumed to be statistically independent directional point sources distributed ov...A theoretical model of ambient sea noise including surface noise sources and stratified medium ocean is discussed. The noise sources are assumed to be statistically independent directional point sources distributed over the ocean surface, and the effects of ocean environment on ambient noise are studied. The normal-mode theory of surface-generated noise is developed, and the normal-mode formula of the directional density function suitable for small grazing angles is analytically continued for being suitable for great grazing angles and consistent with the ray formula. The unified formulae for calculating the intensities, spatial correlation and vertical directivity of ambient sea noise are presented.展开更多
Spatial information remains to be an important topic in geographic information system and in remote sensing fields,and spatial relationships have been increasingly incorporated into the image classification processes....Spatial information remains to be an important topic in geographic information system and in remote sensing fields,and spatial relationships have been increasingly incorporated into the image classification processes.Previous studies have employed multiple occurrences of spatial features(shape,texture,etc.,)to improve classification results.However,less attention has been focused on using higher-level spatial relationships for image classification.In this study,two novel spatial relationships,namely,maximum spatial adjacency(MSA)and directional spatial adjacency(DSA),were proposed to assist in image classification.The proposed methods were implemented to extract buildings,beach,and emergent vegetation land-cover classes according to their spatial relationships with their corresponding reference classes.The promising results obtained from this study suggest that the proposed MSA and DSA spatial relationships can be valuable information in defining rule sets for a more reasonable and accurate classification.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11174235
文摘The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu- merical modeling. An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method. Combining the characteristic of Lloyd＇s mirror interference pattern, the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed. The theoretical pre- diction agrees well with the numerical results. Experimental results confirm the validity of analytical solution. Finally, the applicability of the analytical solution is summarized. The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.
基金The project supported by National Natural Science Foundation of China
文摘A theoretical model of ambient sea noise including surface noise sources and stratified medium ocean is discussed. The noise sources are assumed to be statistically independent directional point sources distributed over the ocean surface, and the effects of ocean environment on ambient noise are studied. The normal-mode theory of surface-generated noise is developed, and the normal-mode formula of the directional density function suitable for small grazing angles is analytically continued for being suitable for great grazing angles and consistent with the ray formula. The unified formulae for calculating the intensities, spatial correlation and vertical directivity of ambient sea noise are presented.
基金This research is partially supported by a NSERC Discovery Grant awarded to Dr.Jinfei Wang,University of Western Ontario.
文摘Spatial information remains to be an important topic in geographic information system and in remote sensing fields,and spatial relationships have been increasingly incorporated into the image classification processes.Previous studies have employed multiple occurrences of spatial features(shape,texture,etc.,)to improve classification results.However,less attention has been focused on using higher-level spatial relationships for image classification.In this study,two novel spatial relationships,namely,maximum spatial adjacency(MSA)and directional spatial adjacency(DSA),were proposed to assist in image classification.The proposed methods were implemented to extract buildings,beach,and emergent vegetation land-cover classes according to their spatial relationships with their corresponding reference classes.The promising results obtained from this study suggest that the proposed MSA and DSA spatial relationships can be valuable information in defining rule sets for a more reasonable and accurate classification.
