Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method （SMM）, is proposed to calculate radar cross section （RCS） of aircraft configura...Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method （SMM）, is proposed to calculate radar cross section （RCS） of aircraft configuration. Based on the geometrical characteristics and the method of moment （MOM）, the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration. The numerical results show that： （1） the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; （2） with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.展开更多
Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Ac...Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.展开更多
This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method...This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method and the surface sound pressure by Rayleigh integral,and expressed the sound radiation power of the structure in a positive definite quadratic form of the Hermitian with an impedance matrix.The ADS analysis of the plate was thus translated into the analysis of structure dynamic sensitivity and ...展开更多
This paper presents a new solution to the problem of transmission cost allocation to its users.The proposed technique utilizes modified Z-bus theory,equivalent current injection and impedance of the generators and loa...This paper presents a new solution to the problem of transmission cost allocation to its users.The proposed technique utilizes modified Z-bus theory,equivalent current injection and impedance of the generators and loads,and is developed by the equal-sharing as well as the orthogonal projection principle.The procedure is performed in three steps.First,the modified Z-bus theory is used to calculate the contribution of the users into the network bus voltages as well as the branch currents.Then,the equal sharing principle is confirmed by the game theory solutions and is subsequently applied to identify the users’contributions into the branch power flows.After that,the orthogonal projections of the contributions are calculated and the concept of effective contributions is suggested.The proposed methodology provides the percentage shares of the users on the network complex variables,which help to better assess the contributions.A 2-bus and the IEEE 30-bus test system are used to validate the proposed technique.Finally,the proposed methodology is applied to the polish 2383-bus system to emphasize its applicability to large practical systems.展开更多
基金National Natural Science Foundation of China (90205020)
文摘Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method （SMM）, is proposed to calculate radar cross section （RCS） of aircraft configuration. Based on the geometrical characteristics and the method of moment （MOM）, the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration. The numerical results show that： （1） the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; （2） with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.
基金supported by the National Natural Science Foundation of China(grant numbers 12072223,12122207,12021002,and 11991032)the EIPHI Graduate School(grant number ANR-17-EURE-0002).
文摘Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.
基金Funded by Doctoral Program Foundation of Institutions of Higher Education of China(20070487403)Natural Science Foundation of Hubei Province of China(2006ABA71)
文摘This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method and the surface sound pressure by Rayleigh integral,and expressed the sound radiation power of the structure in a positive definite quadratic form of the Hermitian with an impedance matrix.The ADS analysis of the plate was thus translated into the analysis of structure dynamic sensitivity and ...
文摘This paper presents a new solution to the problem of transmission cost allocation to its users.The proposed technique utilizes modified Z-bus theory,equivalent current injection and impedance of the generators and loads,and is developed by the equal-sharing as well as the orthogonal projection principle.The procedure is performed in three steps.First,the modified Z-bus theory is used to calculate the contribution of the users into the network bus voltages as well as the branch currents.Then,the equal sharing principle is confirmed by the game theory solutions and is subsequently applied to identify the users’contributions into the branch power flows.After that,the orthogonal projections of the contributions are calculated and the concept of effective contributions is suggested.The proposed methodology provides the percentage shares of the users on the network complex variables,which help to better assess the contributions.A 2-bus and the IEEE 30-bus test system are used to validate the proposed technique.Finally,the proposed methodology is applied to the polish 2383-bus system to emphasize its applicability to large practical systems.
