Source localization by matched-field processing （MFP） can be accelerated by building a database of Green＇s functions which however requires a bulk-storage memory. According to the sparsity of the source locations i...Source localization by matched-field processing （MFP） can be accelerated by building a database of Green＇s functions which however requires a bulk-storage memory. According to the sparsity of the source locations in the search grids of MFP, compressed sensing inspires an approach to reduce the database by introducing a sensing matrix to compress the database. Compressed sensing is further used to estimate the source locations with higher resolution by solving the β -norm optimization problem of the compressed Green＇s function and the data received by a vertieal/horizontal line array. The method is validated by simulation and is verified with the experimental data.展开更多
A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ di...A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed.展开更多
Matched field processing (MFP) is a generalized beamforming method which uses the spatial complexities of acoustic field in an ocean waveguide to localize sources in range, depth and azimuth or to infer parameters of ...Matched field processing (MFP) is a generalized beamforming method which uses the spatial complexities of acoustic field in an ocean waveguide to localize sources in range, depth and azimuth or to infer parameters of the waveguide itself. In the paper, we present simulated and experimental results on narrow-band point source localization in shallow water by the matched field processing of a vertical array. Range-depth ambiguity surfaces are obtained by the spatial correlation of the incident field (modeled or realistic) with a modeled replica of that field. The simulated results indicate that a high-quality ambiguity surface can be obtained in case of perfect match between the 'true' environmental parameters and those used to compute the replica field. The effects of mismatches result in a degraded ambiguity surface and incorrect localization. Examples of localizations obtained with real sea test data are presented. It is shown that the conventional methods have better robustness than the minimum variance distortionless response (MVDR) based method. By employing the reduced minimum variance beamforming (RMVB), we can also get better results.展开更多
Purpose As the key component for the Higgs operating mode of Circular Electron-Positron Collider(CEPC),the electrostatic-magnetic deflectors are required by the double ring collider to separate the electron and the po...Purpose As the key component for the Higgs operating mode of Circular Electron-Positron Collider(CEPC),the electrostatic-magnetic deflectors are required by the double ring collider to separate the electron and the positron beams horizontally in the RF regions.The electric field is required to reach 2 MV/m with the vacuum pressure of less than 2×10^(−10) Torr.The deflectors make use of both electric and magnetic fields to deflect the beams.The incoming beam gets zero deflection,but the outgoing beam is deflected by the combined effect of the electric and magnetic forces.W and Z modes use the same cavities with H mode to save budget.The deflectors are large contributors to the overall beam impedance which is necessary to be reduced as much as possible.Methods The electric and magnetic field optimization has been performed by the Opera.The beam impedance study has been carried out using the Computer Simulation Technology(CST)particle studio.Results The shape of the electrode is optimized for a good electric field homogeneity(±0.05%)in 46 mm×40 mm region.The electric field and the magnetic field could be matched perfectly in the main body of the deflector by bending the elec-trodes and introducing magnetic field clamps and mirror plates.The beam loss factor decreases by about 20%via the intro-duction of ground electrodes and tapering ends.Conclusions The design results successfully meet the physical requirements,and the mechanical design has been finished.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374271 and 11374270the Fundamental Research Funds for the Central Universities under Grant No 201513038
文摘Source localization by matched-field processing （MFP） can be accelerated by building a database of Green＇s functions which however requires a bulk-storage memory. According to the sparsity of the source locations in the search grids of MFP, compressed sensing inspires an approach to reduce the database by introducing a sensing matrix to compress the database. Compressed sensing is further used to estimate the source locations with higher resolution by solving the β -norm optimization problem of the compressed Green＇s function and the data received by a vertieal/horizontal line array. The method is validated by simulation and is verified with the experimental data.
基金Project supported by the National Natural Science Foundation of China(Grant No.11205162)
文摘A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed.
文摘Matched field processing (MFP) is a generalized beamforming method which uses the spatial complexities of acoustic field in an ocean waveguide to localize sources in range, depth and azimuth or to infer parameters of the waveguide itself. In the paper, we present simulated and experimental results on narrow-band point source localization in shallow water by the matched field processing of a vertical array. Range-depth ambiguity surfaces are obtained by the spatial correlation of the incident field (modeled or realistic) with a modeled replica of that field. The simulated results indicate that a high-quality ambiguity surface can be obtained in case of perfect match between the 'true' environmental parameters and those used to compute the replica field. The effects of mismatches result in a degraded ambiguity surface and incorrect localization. Examples of localizations obtained with real sea test data are presented. It is shown that the conventional methods have better robustness than the minimum variance distortionless response (MVDR) based method. By employing the reduced minimum variance beamforming (RMVB), we can also get better results.
基金Thanks to National Key R&D Program of China(Grant No.2018YFA0404301)for the funding to this work.
文摘Purpose As the key component for the Higgs operating mode of Circular Electron-Positron Collider(CEPC),the electrostatic-magnetic deflectors are required by the double ring collider to separate the electron and the positron beams horizontally in the RF regions.The electric field is required to reach 2 MV/m with the vacuum pressure of less than 2×10^(−10) Torr.The deflectors make use of both electric and magnetic fields to deflect the beams.The incoming beam gets zero deflection,but the outgoing beam is deflected by the combined effect of the electric and magnetic forces.W and Z modes use the same cavities with H mode to save budget.The deflectors are large contributors to the overall beam impedance which is necessary to be reduced as much as possible.Methods The electric and magnetic field optimization has been performed by the Opera.The beam impedance study has been carried out using the Computer Simulation Technology(CST)particle studio.Results The shape of the electrode is optimized for a good electric field homogeneity(±0.05%)in 46 mm×40 mm region.The electric field and the magnetic field could be matched perfectly in the main body of the deflector by bending the elec-trodes and introducing magnetic field clamps and mirror plates.The beam loss factor decreases by about 20%via the intro-duction of ground electrodes and tapering ends.Conclusions The design results successfully meet the physical requirements,and the mechanical design has been finished.
