In order to resolve direction finding problems in the impulse noise,a direction of arrival(DOA)estimation method is proposed.The proposed DOA estimation method can restrain the impulse noise by using infinite norm exp...In order to resolve direction finding problems in the impulse noise,a direction of arrival(DOA)estimation method is proposed.The proposed DOA estimation method can restrain the impulse noise by using infinite norm exponential kernel covariance matrix and obtain excellent performance via the maximumlikelihood(ML)algorithm.In order to obtain the global optimal solutions of this method,a quantum electromagnetic field optimization(QEFO)algorithm is designed.In view of the QEFO algorithm,the proposed method can resolve the difficulties of DOA estimation in the impulse noise.Comparing with some traditional DOA estimation methods,the proposed DOA estimation method shows high superiority and robustness for determining the DOA of independent and coherent sources,which has been verified via the Monte-Carlo experiments of different schemes,especially in the case of snapshot deficiency,low generalized signal to noise ratio(GSNR)and strong impulse noise.Beyond that,the Cramer-Rao bound(CRB)of angle estimation in the impulse noise and the proof of the convergence of the QEFO algorithm are provided in this paper.展开更多
Strand electromagnetic stirring（S-EMS） and final electromagnetic stirring（F-EMS） are the main methods used to improve the center porosity and segregation for round blooms. To optimize the stirring conditions, nail...Strand electromagnetic stirring（S-EMS） and final electromagnetic stirring（F-EMS） are the main methods used to improve the center porosity and segregation for round blooms. To optimize the stirring conditions, nail shooting tests were conducted for three sections of large round blooms with diameters of ф380 mm, ф450 mm, and ф600 mm. Acid leaching and sulfur print tests were used to investigate the shell thickness. Based on the results of nail shooting tests, a mathematical model of solidification was established, and the variation of shell thickness and the central solid fraction were exactly calculated by the model. By taking all sections into account, the locations of S-EMS and F-EMS were optimized for each section. In the results, the macro-segregation of various sections is improved after the locations of S-EMS and F-EMS systems are changed.展开更多
Nihility material is a medium whose relative permittivity and permeability tend to zero simultaneously. In this work, comparing with the scattering properties of perfect nihility nanoparticles （made from nihility mat...Nihility material is a medium whose relative permittivity and permeability tend to zero simultaneously. In this work, comparing with the scattering properties of perfect nihility nanoparticles （made from nihility material）, we provide an optimization design of electromagnetic nihility nanoparticles, which is a coated hybrid nanosphere constituted by commutative c-negative （ENG） and μ-negative （MNG） media. Compared to a single ENG or MNG nanosphere, it is found that the total and back scattering spectra of coated hybrid nanospheres are much closer to those of perfect nihility nanospheres. Moreover, it is observed that the scattered electromagnetic field distribution of coated hybrid nanospheres is identical to that of perfect nihility nanospheres. These results indicate that the combination of commutative ENG and MNG media can constitute a composite structure which gives the closest approximation of electromagnetic scattering of perfect nihility nanospheres in a wide frequency range.展开更多
This work presents a novel electromagnetic driving system that consists of eight optimized electromagnets arranged in an optimal configuration and employs a control framework based on an active disturbance rejection c...This work presents a novel electromagnetic driving system that consists of eight optimized electromagnets arranged in an optimal configuration and employs a control framework based on an active disturbance rejection controller(ADRC)and virtual boundary.The optimal system configuration enhances the system’s compatibility with other ophthalmic surgical instruments,while also improving its capacity to generate magnetic force in the vertical direction.Besides,the optimal electromagnet parameters provide a superior comprehensive performance on magnetic field generation capacity and thermal power.Hence,the presented design achieves a stronger capacity for sustained work.Furthermore,the ADRC controller effectively monitors and further compensates the total disturbance as well as gravity to enhance the system’s robustness.Meanwhile,the implementation of virtual boundaries substantially enhances interactive security via collision avoidance.The magnetic and thermal performance tests have been performed on the electromagnet to verify the design optimization.The proposed electromagnet can generate a superior magnetic field of 2.071 mT at a distance of 65 mm with an applied current of 1 A.Moreover,it demonstrates minimal temperature elevation from room temperature(25℃)to 46℃ through natural heat dissipation in 3 h,thereby effectively supporting prolonged magnetic manipulation of intraocular microsurgery.Furthermore,trajectory tracking experiments with disturbances have been performed in a liquid environment similar to the practical ophthalmic surgery scenarios,to verify the robustness and security of the presented control framework.The maximum root mean square(RMS)error of performance tests in different operation modes remains 35.8μm,providing stable support for intraocular microsurgery.展开更多
基金supported by the National Natural Science Foundation of China(61571149)the Natural Science Foundation of Heilongjiang Province(LH2020F017)+1 种基金the Initiation Fund for Postdoctoral Research in Heilongjiang Province(LBH-Q19098)the Heilongjiang Province Key Laboratory of High Accuracy Satellite Navigation and Marine Application Laboratory(HKL-2020-Y01).
文摘In order to resolve direction finding problems in the impulse noise,a direction of arrival(DOA)estimation method is proposed.The proposed DOA estimation method can restrain the impulse noise by using infinite norm exponential kernel covariance matrix and obtain excellent performance via the maximumlikelihood(ML)algorithm.In order to obtain the global optimal solutions of this method,a quantum electromagnetic field optimization(QEFO)algorithm is designed.In view of the QEFO algorithm,the proposed method can resolve the difficulties of DOA estimation in the impulse noise.Comparing with some traditional DOA estimation methods,the proposed DOA estimation method shows high superiority and robustness for determining the DOA of independent and coherent sources,which has been verified via the Monte-Carlo experiments of different schemes,especially in the case of snapshot deficiency,low generalized signal to noise ratio(GSNR)and strong impulse noise.Beyond that,the Cramer-Rao bound(CRB)of angle estimation in the impulse noise and the proof of the convergence of the QEFO algorithm are provided in this paper.
基金financially supported by the National Natural Science Foundation of China(No.51404018)the State Key Laboratory of Advanced Metallurgy Foundation(No.41614014)the National Key Technologies R&D Program of China(No.2015BAF30B01)
文摘Strand electromagnetic stirring（S-EMS） and final electromagnetic stirring（F-EMS） are the main methods used to improve the center porosity and segregation for round blooms. To optimize the stirring conditions, nail shooting tests were conducted for three sections of large round blooms with diameters of ф380 mm, ф450 mm, and ф600 mm. Acid leaching and sulfur print tests were used to investigate the shell thickness. Based on the results of nail shooting tests, a mathematical model of solidification was established, and the variation of shell thickness and the central solid fraction were exactly calculated by the model. By taking all sections into account, the locations of S-EMS and F-EMS were optimized for each section. In the results, the macro-segregation of various sections is improved after the locations of S-EMS and F-EMS systems are changed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174222 and 91230203
文摘Nihility material is a medium whose relative permittivity and permeability tend to zero simultaneously. In this work, comparing with the scattering properties of perfect nihility nanoparticles （made from nihility material）, we provide an optimization design of electromagnetic nihility nanoparticles, which is a coated hybrid nanosphere constituted by commutative c-negative （ENG） and μ-negative （MNG） media. Compared to a single ENG or MNG nanosphere, it is found that the total and back scattering spectra of coated hybrid nanospheres are much closer to those of perfect nihility nanospheres. Moreover, it is observed that the scattered electromagnetic field distribution of coated hybrid nanospheres is identical to that of perfect nihility nanospheres. These results indicate that the combination of commutative ENG and MNG media can constitute a composite structure which gives the closest approximation of electromagnetic scattering of perfect nihility nanospheres in a wide frequency range.
基金supported by the National Natural Science Foundation of China(grant numbers 61973231,92148201,and 51721003).
文摘This work presents a novel electromagnetic driving system that consists of eight optimized electromagnets arranged in an optimal configuration and employs a control framework based on an active disturbance rejection controller(ADRC)and virtual boundary.The optimal system configuration enhances the system’s compatibility with other ophthalmic surgical instruments,while also improving its capacity to generate magnetic force in the vertical direction.Besides,the optimal electromagnet parameters provide a superior comprehensive performance on magnetic field generation capacity and thermal power.Hence,the presented design achieves a stronger capacity for sustained work.Furthermore,the ADRC controller effectively monitors and further compensates the total disturbance as well as gravity to enhance the system’s robustness.Meanwhile,the implementation of virtual boundaries substantially enhances interactive security via collision avoidance.The magnetic and thermal performance tests have been performed on the electromagnet to verify the design optimization.The proposed electromagnet can generate a superior magnetic field of 2.071 mT at a distance of 65 mm with an applied current of 1 A.Moreover,it demonstrates minimal temperature elevation from room temperature(25℃)to 46℃ through natural heat dissipation in 3 h,thereby effectively supporting prolonged magnetic manipulation of intraocular microsurgery.Furthermore,trajectory tracking experiments with disturbances have been performed in a liquid environment similar to the practical ophthalmic surgery scenarios,to verify the robustness and security of the presented control framework.The maximum root mean square(RMS)error of performance tests in different operation modes remains 35.8μm,providing stable support for intraocular microsurgery.
