Multi-angle synthetic aperture radar（SAR） image matching is very challenging, because the same object may cause different backscattering patterns, heavily depending on the radar incident angle. A technique based on ...Multi-angle synthetic aperture radar（SAR） image matching is very challenging, because the same object may cause different backscattering patterns, heavily depending on the radar incident angle. A technique based on the relations between the invariant positions of ground targets among the reference and sensed images is proposed to accommodate the nonmatching patterns. It involves a target extraction using wavelet coefficient fusion, as well as a geometric voting matching routine for searching the matched control points（CPs） in the reference and sensed images, respectively. To accelerate the speed of the search, a robust, rapidly corresponding CPs determination strategy is exploited by utilizing the global spatial transformation model, as well as a procedure of outlier removal to ensure the desired accuracy. Meanwhile, the positions of the matched point pairs are relocated using mutual information. The final warping of the images according to the CPs is performed by using a polynomial function. The results show the possibility of matching multi-angle SAR images in general cases.展开更多
A model for a laser with dual-pass pumping is established, and an equation expressing the mode matching for this structure is presented. Through the numerical analysis of this equation, under the conditions of weak-ab...A model for a laser with dual-pass pumping is established, and an equation expressing the mode matching for this structure is presented. Through the numerical analysis of this equation, under the conditions of weak-absorption and effective absorption efficiency, the optimum radius of the pump beam waist as well as the optimum location is fitted to simple formulas, considering the quality of the pump beam, absorption coefficient, and beam waist of the cavity mode.Using these formulas, the laser with dual-pass pumping could be optimized to obtain a high slope efficiency. To test the utility of this model, an Nd：YVO4 laser with dual-pass pumping and weak-absorption was built and optimized according to the results of the calculation. A good agreement between the results of the calculations and the experiment verified the model and the numerical analysis.展开更多
In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search spac...In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search space.Genetic algorithms are used for the parameter optimization.This method integrates the a posterior probability density（PPD） over environmental parameters to obtain a sequence of marginal probability distributions over source range and depth,from which the most-probable source location and localization uncertainties can be extracted.Considering that the seabed density and attenuation are less sensitive to the objective function of matched field processing,we utilize the empirical relationship to invert those parameters indirectly.The broadband signals recorded by a vertical line array in a Yellow Sea experiment in 2000 are processed and analyzed.It was found that,the Bayesian localization method that incorporates the environmental variability into the processor,made it robust to the uncertainty in the ocean environment.In addition,using the empirical relationship could enhance the localization accuracy.展开更多
To improve the performance of sound source localization based on distributed microphone arrays in noisy and reverberant environments,a sound source localization method was proposed.This method exploited the inherent s...To improve the performance of sound source localization based on distributed microphone arrays in noisy and reverberant environments,a sound source localization method was proposed.This method exploited the inherent spatial sparsity to convert the localization problem into a sparse recovery problem based on the compressive sensing（CS） theory.In this method two-step discrete cosine transform（DCT）-based feature extraction was utilized to cover both short-time and long-time properties of the signal and reduce the dimensions of the sparse model.Moreover,an online dictionary learning（DL） method was used to dynamically adjust the dictionary for matching the changes of audio signals,and then the sparse solution could better represent location estimations.In addition,we proposed an improved approximate l_0norm minimization algorithm to enhance reconstruction performance for sparse signals in low signal-noise ratio（SNR）.The effectiveness of the proposed scheme is demonstrated by simulation results where the locations of multiple sources can be obtained in the noisy and reverberant conditions.展开更多
文摘Multi-angle synthetic aperture radar（SAR） image matching is very challenging, because the same object may cause different backscattering patterns, heavily depending on the radar incident angle. A technique based on the relations between the invariant positions of ground targets among the reference and sensed images is proposed to accommodate the nonmatching patterns. It involves a target extraction using wavelet coefficient fusion, as well as a geometric voting matching routine for searching the matched control points（CPs） in the reference and sensed images, respectively. To accelerate the speed of the search, a robust, rapidly corresponding CPs determination strategy is exploited by utilizing the global spatial transformation model, as well as a procedure of outlier removal to ensure the desired accuracy. Meanwhile, the positions of the matched point pairs are relocated using mutual information. The final warping of the images according to the CPs is performed by using a polynomial function. The results show the possibility of matching multi-angle SAR images in general cases.
文摘A model for a laser with dual-pass pumping is established, and an equation expressing the mode matching for this structure is presented. Through the numerical analysis of this equation, under the conditions of weak-absorption and effective absorption efficiency, the optimum radius of the pump beam waist as well as the optimum location is fitted to simple formulas, considering the quality of the pump beam, absorption coefficient, and beam waist of the cavity mode.Using these formulas, the laser with dual-pass pumping could be optimized to obtain a high slope efficiency. To test the utility of this model, an Nd：YVO4 laser with dual-pass pumping and weak-absorption was built and optimized according to the results of the calculation. A good agreement between the results of the calculations and the experiment verified the model and the numerical analysis.
基金supported by the National Natural Science Foundation of China(11434012,41561144006,10974218,11174312)the Key Laboratory of Marine Surveying and Charting in Universities of Shandong(Shandong University of Science and Technology)(2013A02)+3 种基金the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents under Grant(2014RCJJ004)the Project of the Public Science and Technology Research Funds Projects of Ocean(201305034)the National Key Technology R&D Program(2012BAB16B01)State Key Laboratory of Acoustics,Chinese Academy of Sciences(SKLA201407)
文摘In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search space.Genetic algorithms are used for the parameter optimization.This method integrates the a posterior probability density（PPD） over environmental parameters to obtain a sequence of marginal probability distributions over source range and depth,from which the most-probable source location and localization uncertainties can be extracted.Considering that the seabed density and attenuation are less sensitive to the objective function of matched field processing,we utilize the empirical relationship to invert those parameters indirectly.The broadband signals recorded by a vertical line array in a Yellow Sea experiment in 2000 are processed and analyzed.It was found that,the Bayesian localization method that incorporates the environmental variability into the processor,made it robust to the uncertainty in the ocean environment.In addition,using the empirical relationship could enhance the localization accuracy.
基金supported by the Doctoral Program of Higher Education of China(20133207120007)the National Natural Science Foundation of China(61405094)+1 种基金the Open Research Fund of Jiangsu Key Laboratory of Meteorological Observation and Information Processing(KDXS1408)the Science and Technology Support Project of Jiangsu Province-Industry(BE2014139)
文摘To improve the performance of sound source localization based on distributed microphone arrays in noisy and reverberant environments,a sound source localization method was proposed.This method exploited the inherent spatial sparsity to convert the localization problem into a sparse recovery problem based on the compressive sensing（CS） theory.In this method two-step discrete cosine transform（DCT）-based feature extraction was utilized to cover both short-time and long-time properties of the signal and reduce the dimensions of the sparse model.Moreover,an online dictionary learning（DL） method was used to dynamically adjust the dictionary for matching the changes of audio signals,and then the sparse solution could better represent location estimations.In addition,we proposed an improved approximate l_0norm minimization algorithm to enhance reconstruction performance for sparse signals in low signal-noise ratio（SNR）.The effectiveness of the proposed scheme is demonstrated by simulation results where the locations of multiple sources can be obtained in the noisy and reverberant conditions.
