A fast implementation of the convolution backprojection（CBP）algorithm in spotlight synthetic aperture radar（SAR）is presented based on the fast Fourier transform（FFT）.Traditionally,the computation of the ＇backpr...A fast implementation of the convolution backprojection（CBP）algorithm in spotlight synthetic aperture radar（SAR）is presented based on the fast Fourier transform（FFT）.Traditionally,the computation of the ＇backprojection＇ process is expensive,since resampling in the process is implemented by using the interpolation operation.By analyzing the relative location relationship among different pixels,the algorithm realizes the ＇backprojection＇ using a series of FFTs instead of the interpolation operation.The point target simulation validates that the new algorithm accelerates the CBP algorithm,and the computational rate increases about 85%.展开更多
The spatial impulse response（SIR） method is often used as the ＇gold standard5 in simulation of transient acoustic wave fields due to its high accuracy in the linear domain.However, a high sampling frequency is ofte...The spatial impulse response（SIR） method is often used as the ＇gold standard5 in simulation of transient acoustic wave fields due to its high accuracy in the linear domain.However, a high sampling frequency is often required in order to achieve the high accuracy. As a result, a large amount of data has to be processed. In this paper a fast approach for computing spatial impulse response is proposed to reduce the computation burden. The proposed approach is developed by employing the relationship of SIRs at observed points and SIRs of the projection points on the transducer surface. Two critical parameters used in the proposed approach, the calculation sampling frequency and the interpolation sampling frequency, are then analyzed.Results show that for a 2.25 MHz rectangular transducer with the size of 5 mm×10 mm,a calculation sampling frequency of 1000 MHz and an interpolation sampling frequency of500 MHz can achieve superior performance while improving the computation efficiency 18 times than the direct solving.展开更多
Response prediction is a fundamental yet challenging task in aeronautical engineering,requiring an accurate selection of sensor positions correlated with the target responses to achieve precise predictions. Unfortunat...Response prediction is a fundamental yet challenging task in aeronautical engineering,requiring an accurate selection of sensor positions correlated with the target responses to achieve precise predictions. Unfortunately, in large-scale structures, the rigorous selection of reliable sensor candidates for multi-target responses remains largely unexplored. In this paper, we propose a flexible and generalized framework for selecting the most relevant sensors to the multi-target response and predicting the target response, referred to as the Fast-aware Multi-Target Response Prediction(FMTRP) approach in the spirit of divide-and-conquer. Specifically, first, a multi-task learning module is designed to predict multi-point response tasks at the same time. Simultaneously, we meticulously devise adaptive mechanisms to facilitate loss-term reweighting and encourage prioritization of challenging tasks in multiple prediction tasks. Second, to ensure ease of interpretation,we introduce a hybrid penalty to select sensors at the group-sparsity, individual-sparsity and element-sparsity levels. Finally, due to the substantial number of candidate sensors posing a significant computational burden, we develop a more efficient search strategy and support computation to make the proposed approach applicable in practice, leading to substantial runtime improvements. Extensive experiments on aircraft standard model response datasets and large airliner test flight datasets validate the effectiveness of the proposed approach in identifying sensor locations and simultaneously predicting responses at multiple points. Compared to state-of-the-art methods,the proposed approach achieves an accuracy of over 99% in sinusoidal excitation and exhibits the shortest runtime(3.514 s).展开更多
It is already five years since the 10-year-old experimental law on the organization of villagers committees adopted in November 1987 by the Standing Committee of the National People’s Congress was made permanent, end...It is already five years since the 10-year-old experimental law on the organization of villagers committees adopted in November 1987 by the Standing Committee of the National People’s Congress was made permanent, ending an intense political debate about how much independence villagers committees should be given to manage village affairs and to what extent villagers should be allowed to choose their leaders. It is five years in which the implementation of villagers autonomy as defined by the law proceeded the fastest and the achievements were the most fruitful. Local laws Over the past five years, all places展开更多
In this paper, we introduce a new type of feedback shift register based on words, called G-linear feedback shift register （σ-LFSR） which can make full use of the instructions of modern CPUs so that we can find good...In this paper, we introduce a new type of feedback shift register based on words, called G-linear feedback shift register （σ-LFSR） which can make full use of the instructions of modern CPUs so that we can find good σ-LFSR with simple structure and fast software implementation. After analysis, we find a class of simple σ-LFSR with maximal period and give an algorithm of searching for those σ-LFSRs. As a result, we provide a new optional fast component in the design of modern wordbased stream ciphers.展开更多
In this paper,we first construct an efficient scheme for nonlinear Caputo fractional differential equations with the initial value and the fractional degree 0<α<1.Then,the unconditional stability and the superl...In this paper,we first construct an efficient scheme for nonlinear Caputo fractional differential equations with the initial value and the fractional degree 0<α<1.Then,the unconditional stability and the superlinear convergence with the order 1+αof the proposed scheme are strictly proved and discussed.Due to the nonlocal property of fractional operators,the new scheme is time-consuming for long-time simulations.Thus,a fast implement of the proposed scheme is presented based on the sum-of-exponentials(SOE)approximation for the kernel tα−1 on the interval[h,T]in the Riemann-Liouville integral,where h is the stepsize.Some numerical experiments are provided to support the theoretical results of the new scheme and demonstrate the computational performance of its fast implement.展开更多
基金Supported by the National Natural Science Foundation of China(61071165)the Aeronautical Science Foundation of China(20080152004)+1 种基金the Ph.D.Programs Foundation of Ministry of Education of China(20070280531)the Program for New Century Excellent Talents in University(NCET-09-0069)~~
文摘A fast implementation of the convolution backprojection（CBP）algorithm in spotlight synthetic aperture radar（SAR）is presented based on the fast Fourier transform（FFT）.Traditionally,the computation of the ＇backprojection＇ process is expensive,since resampling in the process is implemented by using the interpolation operation.By analyzing the relative location relationship among different pixels,the algorithm realizes the ＇backprojection＇ using a series of FFTs instead of the interpolation operation.The point target simulation validates that the new algorithm accelerates the CBP algorithm,and the computational rate increases about 85%.
基金supported by the National Natural Science Foundation of China(51074121)the China Postdoctoral Science Foundation(2015M572653XB)+1 种基金the Doctoral Fund of Xi'an University of Science and Technology(2014QDJ003),the Cultivation Fund of Xi'an University of Science and Technology(201332)Scientific Research Program Funded by Shaanxi Provincial Education Department
文摘The spatial impulse response（SIR） method is often used as the ＇gold standard5 in simulation of transient acoustic wave fields due to its high accuracy in the linear domain.However, a high sampling frequency is often required in order to achieve the high accuracy. As a result, a large amount of data has to be processed. In this paper a fast approach for computing spatial impulse response is proposed to reduce the computation burden. The proposed approach is developed by employing the relationship of SIRs at observed points and SIRs of the projection points on the transducer surface. Two critical parameters used in the proposed approach, the calculation sampling frequency and the interpolation sampling frequency, are then analyzed.Results show that for a 2.25 MHz rectangular transducer with the size of 5 mm×10 mm,a calculation sampling frequency of 1000 MHz and an interpolation sampling frequency of500 MHz can achieve superior performance while improving the computation efficiency 18 times than the direct solving.
基金sponsored by the Innovation Foundation for National Natural Science Foundation of China(No.11872312)。
文摘Response prediction is a fundamental yet challenging task in aeronautical engineering,requiring an accurate selection of sensor positions correlated with the target responses to achieve precise predictions. Unfortunately, in large-scale structures, the rigorous selection of reliable sensor candidates for multi-target responses remains largely unexplored. In this paper, we propose a flexible and generalized framework for selecting the most relevant sensors to the multi-target response and predicting the target response, referred to as the Fast-aware Multi-Target Response Prediction(FMTRP) approach in the spirit of divide-and-conquer. Specifically, first, a multi-task learning module is designed to predict multi-point response tasks at the same time. Simultaneously, we meticulously devise adaptive mechanisms to facilitate loss-term reweighting and encourage prioritization of challenging tasks in multiple prediction tasks. Second, to ensure ease of interpretation,we introduce a hybrid penalty to select sensors at the group-sparsity, individual-sparsity and element-sparsity levels. Finally, due to the substantial number of candidate sensors posing a significant computational burden, we develop a more efficient search strategy and support computation to make the proposed approach applicable in practice, leading to substantial runtime improvements. Extensive experiments on aircraft standard model response datasets and large airliner test flight datasets validate the effectiveness of the proposed approach in identifying sensor locations and simultaneously predicting responses at multiple points. Compared to state-of-the-art methods,the proposed approach achieves an accuracy of over 99% in sinusoidal excitation and exhibits the shortest runtime(3.514 s).
文摘It is already five years since the 10-year-old experimental law on the organization of villagers committees adopted in November 1987 by the Standing Committee of the National People’s Congress was made permanent, ending an intense political debate about how much independence villagers committees should be given to manage village affairs and to what extent villagers should be allowed to choose their leaders. It is five years in which the implementation of villagers autonomy as defined by the law proceeded the fastest and the achievements were the most fruitful. Local laws Over the past five years, all places
基金the National Natural Science Foundation of China (Grant No. 60503011)the National High-Tech Research and Development Program of China (863 Program) (Grant No. 2006AA01Z425)the National Basic Research Program of China (973 Program) (Grant No. 2007CB807902)
文摘In this paper, we introduce a new type of feedback shift register based on words, called G-linear feedback shift register （σ-LFSR） which can make full use of the instructions of modern CPUs so that we can find good σ-LFSR with simple structure and fast software implementation. After analysis, we find a class of simple σ-LFSR with maximal period and give an algorithm of searching for those σ-LFSRs. As a result, we provide a new optional fast component in the design of modern wordbased stream ciphers.
基金This research is supported by National Natural Science Foundation of China(Grant No.11701502).
文摘In this paper,we first construct an efficient scheme for nonlinear Caputo fractional differential equations with the initial value and the fractional degree 0<α<1.Then,the unconditional stability and the superlinear convergence with the order 1+αof the proposed scheme are strictly proved and discussed.Due to the nonlocal property of fractional operators,the new scheme is time-consuming for long-time simulations.Thus,a fast implement of the proposed scheme is presented based on the sum-of-exponentials(SOE)approximation for the kernel tα−1 on the interval[h,T]in the Riemann-Liouville integral,where h is the stepsize.Some numerical experiments are provided to support the theoretical results of the new scheme and demonstrate the computational performance of its fast implement.
