随着航天遥感领域高分辨率时间延迟积分成像中行频的提高,在一个积分时间内入瞳能量逐渐减少,在弱光条件下成像品质下降,需要采用增大积分级数的方法弥补能量的不足。现有传统数字域累加势必会导致叠加引入过多噪声,而模拟域又受到器件...随着航天遥感领域高分辨率时间延迟积分成像中行频的提高,在一个积分时间内入瞳能量逐渐减少,在弱光条件下成像品质下降,需要采用增大积分级数的方法弥补能量的不足。现有传统数字域累加势必会导致叠加引入过多噪声,而模拟域又受到器件工艺的影响无法实现大级数累加。文章首先提出了一种基于电荷域和数字域混合的累加方式,并阐述了具体成像方案。同时,结合相机在轨成像方式,对混合域累加方式下的信噪比和调制传递函数(Modulation Transfer Function,MTF)进行了理论推导。文章最后搭建实验环境对混合域累加方式下信噪比和MTF进行测试,并与传统电荷域进行比较,验证了混合域累加理论的正确性以及实现方法的可行性。根据分析与验证,文章所提方法有效的解决了单纯电荷域与数字域的主要瓶颈,为超高分辨率成像领域提供了有效的解决方案。展开更多
A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the ...A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order Taylor series of time base function including time-retardation,the singularity of the integrand can be removed.The surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented technique.Comparisons are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.展开更多
The dynamic ground subsidence due to underground mining is a complicated time-dependent and rate- dependent process. Based. on the theory of rock rheology and probability integral method, this study developed the supe...The dynamic ground subsidence due to underground mining is a complicated time-dependent and rate- dependent process. Based. on the theory of rock rheology and probability integral method, this study developed the superposltlOn model for the prediction and analysis of the ground dynamic subsidence in mining area of thick !oose layer. The model consists of two parts （the prediction of overlying bedrock and the prediction of thick loose layer）. The overlying bedrock is regarded as visco-elastic beam, of which the dynamic subsidence is predicted by the Kelvin visco-elastic rheological model. The thick loose layer is regarded as random medium, and the ground dynamic subsidence, is predicted by the probability integral model. At last, the two prediction models are vertically stacked in the same coordinate system, and the bedrock dynamic subsidence is regarded as a variable mining thickness input into the prediction model of ground dynamic subsidence. The prediction results obtained were compared w^th actual movement and deformation data from Zhao I and Zhao II mine, central China. The agreement of the prediction results with the. field measurements.show that the superposition model （SM） is more satisfactory and the formulae obtained are more effective than the classical single probability Integral model（SPIM）, and thus can be effectively used for predicting the ground dynamic subsidence in mining area of thick loose layer.展开更多
文摘随着航天遥感领域高分辨率时间延迟积分成像中行频的提高,在一个积分时间内入瞳能量逐渐减少,在弱光条件下成像品质下降,需要采用增大积分级数的方法弥补能量的不足。现有传统数字域累加势必会导致叠加引入过多噪声,而模拟域又受到器件工艺的影响无法实现大级数累加。文章首先提出了一种基于电荷域和数字域混合的累加方式,并阐述了具体成像方案。同时,结合相机在轨成像方式,对混合域累加方式下的信噪比和调制传递函数(Modulation Transfer Function,MTF)进行了理论推导。文章最后搭建实验环境对混合域累加方式下信噪比和MTF进行测试,并与传统电荷域进行比较,验证了混合域累加理论的正确性以及实现方法的可行性。根据分析与验证,文章所提方法有效的解决了单纯电荷域与数字域的主要瓶颈,为超高分辨率成像领域提供了有效的解决方案。
文摘A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order Taylor series of time base function including time-retardation,the singularity of the integrand can be removed.The surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented technique.Comparisons are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.
基金provided by the National Natural Science Foundation of China Youth Found of China (No.41102169)the doctoral foundation of Henan Polytechnic University of China (No. B2014-056)
文摘The dynamic ground subsidence due to underground mining is a complicated time-dependent and rate- dependent process. Based. on the theory of rock rheology and probability integral method, this study developed the superposltlOn model for the prediction and analysis of the ground dynamic subsidence in mining area of thick !oose layer. The model consists of two parts （the prediction of overlying bedrock and the prediction of thick loose layer）. The overlying bedrock is regarded as visco-elastic beam, of which the dynamic subsidence is predicted by the Kelvin visco-elastic rheological model. The thick loose layer is regarded as random medium, and the ground dynamic subsidence, is predicted by the probability integral model. At last, the two prediction models are vertically stacked in the same coordinate system, and the bedrock dynamic subsidence is regarded as a variable mining thickness input into the prediction model of ground dynamic subsidence. The prediction results obtained were compared w^th actual movement and deformation data from Zhao I and Zhao II mine, central China. The agreement of the prediction results with the. field measurements.show that the superposition model （SM） is more satisfactory and the formulae obtained are more effective than the classical single probability Integral model（SPIM）, and thus can be effectively used for predicting the ground dynamic subsidence in mining area of thick loose layer.
