In passive bistatic radar,the computational efficiency of clutter suppression algorithms remains low,due to continuous increases in bandwidth for potential illuminators of opportunity and the use of multi-source detec...In passive bistatic radar,the computational efficiency of clutter suppression algorithms remains low,due to continuous increases in bandwidth for potential illuminators of opportunity and the use of multi-source detection frameworks.Accordingly,we propose a lightweight version of the extensive cancellation algorithm(ECA),which achieves clutter suppression performance comparable to that of ECA while reducing the computational and space complexities by at least one order of magnitude.This is achieved through innovative adjustments to the reference signal subspace matrix within the ECA framework,resulting in a redefined approach to the computation of the autocorrelation matrix and cross-correlation vector.This novel modification significantly simplifies the computational aspects.Furthermore,we introduce a dimension-expanding technique that streamlines clutter estimation.Overall,the proposed method replaces the computation-intensive aspects of the original ECA with fast Fourier transform(FFT)and inverse FFT operations,and eliminates the construction of the memory-intensive signal subspace.Comparing the proposed method with ECA and its batched version(ECA-B),the central advantages are more streamlined implementation and minimal storage requirements,all without compromising performance.The efficacy of this approach is demonstrated through both simulations and field experimental results.展开更多
The boundary between the near and far fields is generally defined as the distance from the vibration source beyond which ground vibrations are mainly dominated by Rayleigh waves. It is closely related to the type of v...The boundary between the near and far fields is generally defined as the distance from the vibration source beyond which ground vibrations are mainly dominated by Rayleigh waves. It is closely related to the type of vibration source and the soil properties. Based on the solutions of the Lamb＇s problem, the boundary at the surface between the near and far fields of ground vibration was investigated for a harmonic vertical concentrated load and an infinite line load at the surface of a visco-elastic half-space. Particularly, the variation of the boundary with the material damping was investigated for both cases. The results indicate that the material damping slightly contributes to the attenuation of vibrations in the near-source region, but significantly reduces the vibrations in the region that is at some distance away from the source. When taking the material damping into consideration, the boundary between the near and far fields tends to move towards the vibration source. Compared with the vibrations caused by a concentrated load, the vibrations induced by an infinite line load can affect a larger range of the surrounding environment, and they attenuate more slowly. This means the boundary between the near field and far field should move fitrther away from the source. Finally, the boundaries are defined in terms of R-wave length （2R） and Poisson ratio of the ground （o）. For the case of a point load, the boundary is located at the distance of （5.0-6.0）2R for v≤0.30 and at the distance of （2.0--3.0）2R for v≥0.35. For the case of an infinite line load, the boundary is located at the distance （5.5-6.5）2rt for v≤0.30 and at the distance （2.5--3.5）2R for v≥0.35.展开更多
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LZ23F030002)the Science and Technology Program of Zhejiang Provincial Department of Transportation(No.2024012)the Talent Funding Project of Zhejiang Institute of Communications(Nos.822321KY0127 and 2024JK05)。
文摘In passive bistatic radar,the computational efficiency of clutter suppression algorithms remains low,due to continuous increases in bandwidth for potential illuminators of opportunity and the use of multi-source detection frameworks.Accordingly,we propose a lightweight version of the extensive cancellation algorithm(ECA),which achieves clutter suppression performance comparable to that of ECA while reducing the computational and space complexities by at least one order of magnitude.This is achieved through innovative adjustments to the reference signal subspace matrix within the ECA framework,resulting in a redefined approach to the computation of the autocorrelation matrix and cross-correlation vector.This novel modification significantly simplifies the computational aspects.Furthermore,we introduce a dimension-expanding technique that streamlines clutter estimation.Overall,the proposed method replaces the computation-intensive aspects of the original ECA with fast Fourier transform(FFT)and inverse FFT operations,and eliminates the construction of the memory-intensive signal subspace.Comparing the proposed method with ECA and its batched version(ECA-B),the central advantages are more streamlined implementation and minimal storage requirements,all without compromising performance.The efficacy of this approach is demonstrated through both simulations and field experimental results.
基金Project(51178342)supported by the National Natural Science Foundation of ChinaProject(KLE-TJGE-C1301)supported by the Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education(Tongji University)under the International Cooperation and Exchange Program,China
文摘The boundary between the near and far fields is generally defined as the distance from the vibration source beyond which ground vibrations are mainly dominated by Rayleigh waves. It is closely related to the type of vibration source and the soil properties. Based on the solutions of the Lamb＇s problem, the boundary at the surface between the near and far fields of ground vibration was investigated for a harmonic vertical concentrated load and an infinite line load at the surface of a visco-elastic half-space. Particularly, the variation of the boundary with the material damping was investigated for both cases. The results indicate that the material damping slightly contributes to the attenuation of vibrations in the near-source region, but significantly reduces the vibrations in the region that is at some distance away from the source. When taking the material damping into consideration, the boundary between the near and far fields tends to move towards the vibration source. Compared with the vibrations caused by a concentrated load, the vibrations induced by an infinite line load can affect a larger range of the surrounding environment, and they attenuate more slowly. This means the boundary between the near field and far field should move fitrther away from the source. Finally, the boundaries are defined in terms of R-wave length （2R） and Poisson ratio of the ground （o）. For the case of a point load, the boundary is located at the distance of （5.0-6.0）2R for v≤0.30 and at the distance of （2.0--3.0）2R for v≥0.35. For the case of an infinite line load, the boundary is located at the distance （5.5-6.5）2rt for v≤0.30 and at the distance （2.5--3.5）2R for v≥0.35.
