To handle the electromagnetic problems of the bi-static radar cross section （RCS） calculation of scatterer in a wide fre- quency band, a finite-difference time-domain （FDTD） extrapolation method combining with dis...To handle the electromagnetic problems of the bi-static radar cross section （RCS） calculation of scatterer in a wide fre- quency band, a finite-difference time-domain （FDTD） extrapolation method combining with discrete Fourier transform （DFT） is pro- posed. By comparing the formulas between the steady state field extrapolation method and the transient field extrapolation method, a novel extrapolation method combining with DFT used in FDTD is proposed when a transient field incident wave is introduced. With the proposed method, the full-angle RCS distribution in a wide fre- quency band can be achieved through one-time FDTD calculation. Afterwards, the back-scattering RCS distributions of a double olive body and a sphere-cone body are calculated. Numerical results verify the validity of the proposed method.展开更多
The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（M...The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（MLFMA） memory,a new parallelization strategy and a modified data octree construction scheme are proposed to further reduce communication in order to improve parallel efficiency.For far interaction,a new scheme called dynamic memory allocation is developed.To analyze the workload balancing performance of a parallel implementation,the original concept of workload balancing factor is introduced and verified by numerical examples.Numerical results show that the above measures improve the parallel efficiency and are suitable for the analysis of electrical large-scale scattering objects.展开更多
When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour...When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour integral. The integrand is expanded to Taylor series and the integral results in a closed form. The cut-off error is analyzed to show that the series converges fast and only about 2 terms can agree wel with the accurate result. The comparison of the perfect electric conductive （PEC） sphere＇s bi-static radar cross section （RCS） using MoM and the accurate method validates the feasibility in manipulating the singularity. The error due to the facet size and the cut-off terms of the series are analyzed in examples.展开更多
The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurem...The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurements. There are numerous polarimetric calibration algorithms. Some complex expressions in these algo-rithms cannot be easily used in an engineering practice. A radar polarimetric coefficients matrix （RPCM） with a simpler expression is presented for the monostatic radar polarization scattering matrix （PSM） measurement. Using a rhombic dihedral corner reflector and a metal ic sphere, the RPCM can be obtained by solving a set of equations, which can be used to find the true PSM for any target. An example for the PSM of a metal ic dish shows that the proposed method obviously improves the accuracy of cross-polarized RCS measurements.展开更多
As a marked extension of the traditional MoM-PO （method of moment-physical optics） hybrid method, a new hybridization of PO, SBR, and MoM （MoM-SBR/PO） is presented to calculate the multireflection contribution in ...As a marked extension of the traditional MoM-PO （method of moment-physical optics） hybrid method, a new hybridization of PO, SBR, and MoM （MoM-SBR/PO） is presented to calculate the multireflection contribution in the PO region efficiently by introducing the method of SBR based on RDN notion, which avoids the time-consuming iterative procedure and the choice of proper Green＇s function. As compared with the traditional MoM-PO hybrid method, the calculation efficiency of the proposed method is greatly improved, and its validity is verified by numerical results.展开更多
The electromagnetic scattering of chiral metamaterials is simulated with the Mie series method.Based on the spherical harmonics vector function in chiral metamaterials,the electromagnetic fields inside and outside of ...The electromagnetic scattering of chiral metamaterials is simulated with the Mie series method.Based on the spherical harmonics vector function in chiral metamaterials,the electromagnetic fields inside and outside of chiral metamaterials sphere are expanded.By applying the continuous boundary condition between the chiral metamaterials and surrounding medium,and the transformation from linearly to circularly polarized electric field components,the co-polarized and cross-polarized bistatic radar cross scattering（RCS） of chiral metamaterials sphere are given.How to overcome the instability of chiral metamaterials sphere of Mie series formula is discussed.The electromagnetic scattering of chiral metamaterials,normal media and metamaterials are compared.The numerical results show that the existence of chirality ξ of chiral metamaterials can decrease the bistatic RCS compared with the same size as normal media sphere.展开更多
This paper proposes a novel composite dual-control bycombing the integral sliding mode control （ISMC） method basedon the finite time convergence theory with extended state observer（ESO） for a tracking problem of a...This paper proposes a novel composite dual-control bycombing the integral sliding mode control （ISMC） method basedon the finite time convergence theory with extended state observer（ESO） for a tracking problem of a missile with tail fins and reactionjetcontrol system （RCS）. First, the ISMC method based on finitetime convergence is utilized to design the control law of tail fins andthe pulse control of RCS for the dual-control system, ensuring thesystem with rapid response and high accuracy of tracking. Then,ESO is employed for the estimation of aerodynamic disturbancesinfluenced by the airflow of thruster jets. With the characteristicof high accuracy estimation of ESO, the chattering free trackingperformance of the attack angle command and the robustnessof the control law are achieved. Meanwhile, the stability of thedual-control system is analyzed based on finite time convergencestability theorem and Lyapunov’s theorem. Finally, numerical simulationsdemonstrate the effectiveness of the proposed design.展开更多
基金supported by the National Natural Science Foundation of China(61401361)the Fundamental Research Funds for the Central Universities of China(31020150104)
文摘To handle the electromagnetic problems of the bi-static radar cross section （RCS） calculation of scatterer in a wide fre- quency band, a finite-difference time-domain （FDTD） extrapolation method combining with discrete Fourier transform （DFT） is pro- posed. By comparing the formulas between the steady state field extrapolation method and the transient field extrapolation method, a novel extrapolation method combining with DFT used in FDTD is proposed when a transient field incident wave is introduced. With the proposed method, the full-angle RCS distribution in a wide fre- quency band can be achieved through one-time FDTD calculation. Afterwards, the back-scattering RCS distributions of a double olive body and a sphere-cone body are calculated. Numerical results verify the validity of the proposed method.
基金supported by the National Basic Research Program of China (973 Program) (61320)
文摘The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（MLFMA） memory,a new parallelization strategy and a modified data octree construction scheme are proposed to further reduce communication in order to improve parallel efficiency.For far interaction,a new scheme called dynamic memory allocation is developed.To analyze the workload balancing performance of a parallel implementation,the original concept of workload balancing factor is introduced and verified by numerical examples.Numerical results show that the above measures improve the parallel efficiency and are suitable for the analysis of electrical large-scale scattering objects.
基金supported by the National Natural Science Foundationof China for the Youth(51307004)
文摘When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour integral. The integrand is expanded to Taylor series and the integral results in a closed form. The cut-off error is analyzed to show that the series converges fast and only about 2 terms can agree wel with the accurate result. The comparison of the perfect electric conductive （PEC） sphere＇s bi-static radar cross section （RCS） using MoM and the accurate method validates the feasibility in manipulating the singularity. The error due to the facet size and the cut-off terms of the series are analyzed in examples.
基金supported by the National Basic Research Program of China(973 Program)(2010CB731905)
文摘The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurements. There are numerous polarimetric calibration algorithms. Some complex expressions in these algo-rithms cannot be easily used in an engineering practice. A radar polarimetric coefficients matrix （RPCM） with a simpler expression is presented for the monostatic radar polarization scattering matrix （PSM） measurement. Using a rhombic dihedral corner reflector and a metal ic sphere, the RPCM can be obtained by solving a set of equations, which can be used to find the true PSM for any target. An example for the PSM of a metal ic dish shows that the proposed method obviously improves the accuracy of cross-polarized RCS measurements.
文摘As a marked extension of the traditional MoM-PO （method of moment-physical optics） hybrid method, a new hybridization of PO, SBR, and MoM （MoM-SBR/PO） is presented to calculate the multireflection contribution in the PO region efficiently by introducing the method of SBR based on RDN notion, which avoids the time-consuming iterative procedure and the choice of proper Green＇s function. As compared with the traditional MoM-PO hybrid method, the calculation efficiency of the proposed method is greatly improved, and its validity is verified by numerical results.
基金supported by the National Natural Science Founda-tion of China (6100102741104097)+2 种基金the Fundamental Research Funds for the Central Universities (ZYGX2010J046ZYGX2011J045ZTGX2009J041)
文摘The electromagnetic scattering of chiral metamaterials is simulated with the Mie series method.Based on the spherical harmonics vector function in chiral metamaterials,the electromagnetic fields inside and outside of chiral metamaterials sphere are expanded.By applying the continuous boundary condition between the chiral metamaterials and surrounding medium,and the transformation from linearly to circularly polarized electric field components,the co-polarized and cross-polarized bistatic radar cross scattering（RCS） of chiral metamaterials sphere are given.How to overcome the instability of chiral metamaterials sphere of Mie series formula is discussed.The electromagnetic scattering of chiral metamaterials,normal media and metamaterials are compared.The numerical results show that the existence of chirality ξ of chiral metamaterials can decrease the bistatic RCS compared with the same size as normal media sphere.
基金supported by the National Natural Science Foundation of China(11202024)
文摘This paper proposes a novel composite dual-control bycombing the integral sliding mode control （ISMC） method basedon the finite time convergence theory with extended state observer（ESO） for a tracking problem of a missile with tail fins and reactionjetcontrol system （RCS）. First, the ISMC method based on finitetime convergence is utilized to design the control law of tail fins andthe pulse control of RCS for the dual-control system, ensuring thesystem with rapid response and high accuracy of tracking. Then,ESO is employed for the estimation of aerodynamic disturbancesinfluenced by the airflow of thruster jets. With the characteristicof high accuracy estimation of ESO, the chattering free trackingperformance of the attack angle command and the robustnessof the control law are achieved. Meanwhile, the stability of thedual-control system is analyzed based on finite time convergencestability theorem and Lyapunov’s theorem. Finally, numerical simulationsdemonstrate the effectiveness of the proposed design.
