A novel method for source effect correction based on integral equation method is proposed.By taking the electrical horizontal field Ex of current source as an example,the correction method is validated using both simu...A novel method for source effect correction based on integral equation method is proposed.By taking the electrical horizontal field Ex of current source as an example,the correction method is validated using both simulated data and field data.The results show that the correction method is feasible and effective for isotropic media.When the field data are processed,the correction method normalizes the sources with different geological structures,which eliminates the geological difference among sources,and retains the geological difference among receivers.The correction results are in line with the expectation in whole.展开更多
This paper summarizes a theoretical design analysis for the implementation of an electromagnetic modeling tool, focusing on the simulation of electromagnetic field propagation inside reverberation chambers. The simula...This paper summarizes a theoretical design analysis for the implementation of an electromagnetic modeling tool, focusing on the simulation of electromagnetic field propagation inside reverberation chambers. The simulation algorithms which have been developed rely on a ray tracing technique, adapted in such a way as to maximize compatibility with the specific requirements and parameters, as applicable for reverberation chambers. The most significant example of a typical parameter is the high rate of wave reflections inside the chambers’ cavity. An implementation of the algorithms was used for simulation of several theoretically predictable cases. Study of the results of these test cases showed that some of the design decisions and algorithms used need to be reviewed in order to optimize the computational aspects of the application, such as resource management (memory, CPU time). Results of typical sample cases are re- viewed in this paper as well, in order to identify possible pitfalls and objectives for future research.展开更多
Based on an analogy among the governing equations among the electrostatic field,static magnetic field and fluid flow,all these equations can be expressed by a general differential equation,and the control volume metho...Based on an analogy among the governing equations among the electrostatic field,static magnetic field and fluid flow,all these equations can be expressed by a general differential equation,and the control volume method,which has been widely used in computational fluid dynamics,was developed to solve all these equations.Numerical results showed that control volume method is a successful numerical in the computational fluid dynamics and the electromagnetics,and the upwind(or downwind)scheme have the clear mathematical meaning and can be applied to calculate the charges' movement in the electrostatic field.展开更多
We investigated how density and quality of mesh around interest domain affect electromagnetic （EM） responses of 3D Earth layered media using finite element method （FEM）. Effect of different mesh shapes was also in...We investigated how density and quality of mesh around interest domain affect electromagnetic （EM） responses of 3D Earth layered media using finite element method （FEM）. Effect of different mesh shapes was also investigated using a method of mixing structured and unstructured mesh. As a case study, we estimated the effects of meshing on selectivity phenomenon of seismic electric signal （SES）. Our results suggest that the relative errors resulting from mesh effects may not be negligible, which may lead to some unconvincing explanation of the SES selectivity based on the numerical modeling results.展开更多
This paper summarizes recent research findings concerning centrioles, centriole duplication, centriole overduplication, supernumerary centrioles, centrosomes, and centrosome amplification. The paper then discusses the...This paper summarizes recent research findings concerning centrioles, centriole duplication, centriole overduplication, supernumerary centrioles, centrosomes, and centrosome amplification. The paper then discusses the status of ongoing research on the use of nanoparticles for cancer treatment. The research findings show that a centriole produces an electromagnetic field apparently due to the longitudinal oscillation of its microtubules (MTs). A cluster of centrioles is therefore presumed to produce an enhanced electromagnetic field. Individual centrioles are immersed in a cloud of electron-dense material (proteins) which together with the centrioles is known as the centrosome. A cluster of centrioles thus produces a cluster of centrosomes—a hallmark of cancer cells. With enhanced electromagnetic fields, centrosome clusters provide an attraction for magnetically charged nanoparticles. These nanoparticles however are not attracted to normal cells which with only two (or at most four) centrioles, have a weaker magnetic field. The idea is simple: Magnetized and therapeutic nanoparticles are directed toward tumors and then attracted to the centrosome clusters of the tumor cells. Once inside the tumor cells, the nanoparticles can release their toxins.展开更多
A class of finite step iterative methods, conjugate gradients, for the solution of an operator equation, is presented on this paper to solve electromagnetic scattering. The method of generalized equivalent circuit is ...A class of finite step iterative methods, conjugate gradients, for the solution of an operator equation, is presented on this paper to solve electromagnetic scattering. The method of generalized equivalent circuit is used to model the problem and then deduce an electromagnetic equation based on the impedance operator. Four versions of the conjugate gradient method are presented and numerical results for an iris structure are given, to illustrate convergence properties of each version. Computational efficiency of these methods has been compared to the moment method.展开更多
This paper research is the first part of the scientific theory that seeks to unify the sciences of physics with the minimal number of mathematical formulas as possible. We will prove that all equations of forces in na...This paper research is the first part of the scientific theory that seeks to unify the sciences of physics with the minimal number of mathematical formulas as possible. We will prove that all equations of forces in nature can be concised in two mathematical formulas, no difference between gravitational or electrical forces or any other type of Types of conventional forces, and through the equivalence of the concepts of matrix and vector, in this theory we will be linking the four-dimensional forces equations with the classical physics as an introduction to connect the rest of the physical sciences.展开更多
Flexible electromagnetics,as an emerging and interdisciplinary field,integrates traditional electromagnetic functions such as the transmission,radiation,receiving,and processing of electromagnetic waves with advanced ...Flexible electromagnetics,as an emerging and interdisciplinary field,integrates traditional electromagnetic functions such as the transmission,radiation,receiving,and processing of electromagnetic waves with advanced flexible electronic technol-ogies.This integration overcomes the inherent limitations of traditional rigid electromagnetic devices,thereby significantly expanding the applicability of electromagnetic technology in complex environments.It provides new research avenues and directions for the application of electromagnetic technology in cutting-edge fields such as smart healthcare,artificial intelligence,and aerospace.This paper provides a comprehensive overview of recent advancements in flexible electromagnetics from four key aspects:materials,de-vices,integration,and applications.Firstly,we provide a succinct introduction to flexible electromagnetic materials including metallic materials,inorganic nonmetallic materials,polymer materials,and composite materials.Then,we explore the development status of flexible electromagnetic devices such as antennas,radio frequency resonators,and electromagnetic shielding devices.Furthermore,we survey the advancements and applications of flexible electromagnetic integrated system in the fields of intelligent medical treat-ment and intelligent information perception.Finally,we summarize the current challenges in the field of flexible electromagnetics and provide a preliminary outlook on future development trends.展开更多
Transformation optics(TO)or transformation acoustics(TA)theory provides an elegant framework for designing intricate wavematerial interaction devices.Combining TO or TA with emerging metamaterial technology,the propag...Transformation optics(TO)or transformation acoustics(TA)theory provides an elegant framework for designing intricate wavematerial interaction devices.Combining TO or TA with emerging metamaterial technology,the propagating waves inside metamaterials can be guided at will by mapping a preset spatial pattern onto a specific constituent parameter distribution,thus achieving desired functionalities.In this review,we mainly focus on recent progress in TO and TA,in terms of basic theory and representative applications.Firstly,we introduce the fundamental principles of TO and TA.Subsequently,we present some related spatial-transformation-based applications in electromagnetics,such as cloaks,beam manipulation devices and applications in nonlinear responses,and some typical applications in acoustics,namely underwater ultrasound invisibility,sound imaging lenses and parity-time symmetry.Furthermore,we discuss transformation-based devices for acoustic-electromagneticjoint control.Finally,we summarize current spatial-transformation-based wave modulations and outline some future opportunities in this research field.展开更多
Subwavelength electromagnetics is a disci- pline that deals with light-matter interaction at subwave- length scale and innovative technologies that control electromagnetic waves with subwavelength structures. Although...Subwavelength electromagnetics is a disci- pline that deals with light-matter interaction at subwave- length scale and innovative technologies that control electromagnetic waves with subwavelength structures. Although the history can be dated back to almost one hundred years ago, the flourish of these researching areas have been no more than 30 years. In this paper, we gave a brief review of the history, current status and future trends of subwavelength electromagnetics. In particular, the milestones related with metamaterials, plasmonics, meta- surfaces and photonic crystals are highlighted.展开更多
The development of materials with excellent microwave absorption(MWA)and electromagnetic interference(EMI)shielding performances has currently received attention.Herein,mesophase pitch-based carbon foam(MPCF)with 3D i...The development of materials with excellent microwave absorption(MWA)and electromagnetic interference(EMI)shielding performances has currently received attention.Herein,mesophase pitch-based carbon foam(MPCF)with 3D interconnected pore structure was prepared through the high pressure pyrolysis of mesophase coal tar pitch.It is found that the 3D interconnected cellular pores of MPCF facilitate multiple reflections of electromagnetic waves,which results in the minimum reflection loss(RLmin)value of MPCF reaches-37.84 dB with the effective absorption bandwidth(EAB)of 5.44 GHz at a thickness of 2.70 mm,and the total average electromagnetic shielding effectiveness(SE_(T))under 3.00 mm thickness achieves 26.52 dB in X-band.Subsequently,MPCF is activated by KOH to obtain activated carbon foam(A-MPCF).The average SE_(T)of A-MPCF achieves 103.00 dB for abundant nanopores on the pore cell walls,which leads to a transition from the multiple reflections of electromagnetic waves on the walls to diffuse reflection.Unfortunately,the reflection coefficient(R)of A-MPCF increases from 0.78 to 0.90.To reduce the R value,Fe_(3)O_(4)/A-MPCF was fabricated via the in situ growth of nano Fe_(3)O_(4)on A-MPCF.Consequently,the R value of Fe_(3)O_(4)/A-MPCF was reduced from 0.90 to 0.74,whereas the MWA performance was only slightly decreased.This work proposes a simple strategy for simultaneously adjusting MWA and EMI shielding performances of materials.展开更多
This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relativ...This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relative motion dynamics model,a prescribed time output feedback control strategy is proposed.A prescribed-time extended state observer is designed to estimate the relative velocity and external disturbances.The disturbance estimates are then used as the feedforward component of the controller.Building on this framework,a novel prescribed-time active disturbance rejection control strategy for position tracking is developed via a backstepping control design.The convergence of the extended state observer and the stability of the closed-loop system are rigorously analyzed using Lyapunov stability theory.Numerical simulations are performed to validate the effectiveness of the proposed controller.展开更多
The multi-satellite electromagnetic formation flight system is nonlinear and strongly coupled,which makes modeling and optimization challenging.To simplify electromagnetic force evaluation and dynamics modeling,we int...The multi-satellite electromagnetic formation flight system is nonlinear and strongly coupled,which makes modeling and optimization challenging.To simplify electromagnetic force evaluation and dynamics modeling,we introduce a reference frame consistent with each satellite body frame,in which the electromagnetic dipoles and electromagnetic forces are represented as two-dimensional vectors.Then,the maneuver time is divided into time intervals,and different satellite sets are activated in each interval,converting the multi-satellite formation reconfiguration problem into an optimal trajectory problem of each two-satellite subsystem.To this end,a token-based dynamic programming method with a switching penalty of active satellite sets is proposed to determine the sequence of satellite sets participating in each time interval,thereby enabling all satellites to reach their desired states.For the two-satellite subsystem with the objectives of minimizing maneuver time and energy consumption,the Gauss pseudo-spectral method is employed to generate the optimal reconfiguration trajectory.Numerical simulations verify the effectiveness of the proposed optimization method.展开更多
While many techniques have been developed for the design of different types of antennas,such as wire antenna,patch antenna,lenses,and reflectors,these cannot be said general-purpose strategies for the synthesis and de...While many techniques have been developed for the design of different types of antennas,such as wire antenna,patch antenna,lenses,and reflectors,these cannot be said general-purpose strategies for the synthesis and design of antennas to achieve the performance characteristics specified by users.Recently,there has been an increasing need for the development of antenna design techniques because of the advent of 5 G and a variety of space,defense,biological,and similar applications,for which a robust and general-purpose design tool is not to be developed.The main objective of this study is to take a look at antenna design from the field manipulation point of view,which has the potential to partially fulfill this need.We review the existing field manipulation techniques,including field transformation methods based on Maxwell’s and wave equations,point out some limitations of these techniques,and then present ways to improve the performance of these methods.Next,we introduce an alternative approach for field manipulation based on two-dimensional(2 D)metasurfaces,and present laws of the generalized reflection and refraction that are based on 2 D surface electromagnetics.Then,we explore how to overcome the limitations of conventional reflection and refraction processes that are strictly bounded by the critical angle.Finally,we provide some application examples of field manipulation methods in the antenna design,with a view on developing a general-purpose strategy for antenna design for future communication.展开更多
Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the...Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.展开更多
With the rapid development of intelligent electronic and military equipment,multifunctional flexible materials that integrat electromagnetic interference(EMI)shielding,temperature sensing,and information encryption ar...With the rapid development of intelligent electronic and military equipment,multifunctional flexible materials that integrat electromagnetic interference(EMI)shielding,temperature sensing,and information encryption are urgently required.This study presents a bio-inspired hierarchical composite foam fabricated using supercritical nitrogen foaming technology.This material exhibits a honeycomb structure,with pore cell sizes controllable within a range of 30–92μm by regulating the filler.The carbon fiber felt(CFf)provides efficient reflection of electromagnetic waves,while the chloroprene rubber/carbon fiber/carbon black foam facilitates both wave absorption and temperature monitoring through its optimized conductive network.This synergistic mechanism results in an EMI shielding effectiveness(SE)of 60.06 d B with excellent temperature sensing performance(The temperature coefficient of resistance(TCR)is-2.642%/℃)in the 24–70℃ range.Notably,the material has a thermal conductivity of up to 0.159 W/(m·K),and the bio-inspired layered design enables information encryption,demonstrating the material's potential for secure communication applications.The foam also has tensile properties of up to 5.13 MPa and a tear strength of 33.02 N/mm.This biomimetic design overcomes the traditional limitations of flexible materials and provides a transformative solution for next-generation applications such as flexible electronics,aerospace systems and military equipment,which urgently need integrated electromagnetic protection,thermal management and information security.展开更多
Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based...Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based nonwoven fabric(PFN_y)is prepared by alkali treatment,Fe~(3+)ion exchange,thermal reduction,and electroless nickel(Ni)plating process.Its impedance/insulation characteristics can be easily adjusted by controlling the in situ growth of Fe_(3)O_(4) and electroless nickel plating.Subsequently,a new strategy of constructing hierarchical dual-gradient impedance/insulation structure is implemented to achieve EMI shielding,radar and infrared stealth via stacking PFN_y with gradually decreased impedance/insulation characteristics from top to bottom.The formation of impedance matching gradient structure promotes effective introduction and dissipation of electromagnetic waves,endowing the composite with outstanding EMI shielding and radar stealth performance.Meanwhile,the construction of thermal insulation gradient structure can effectively inhibit thermal radiation from target,bringing an excellent infrared stealth performance.Importantly,the strong interfacial interactions between Fe_(3)O_(4),Ni and polyimide fiber accelerate PFNy to resist the stresses originated from high-temperature heat source,achieving a compatible high-temperature resistant radar/infrared stealth performance.Such excellent comprehensive properties endow it with a great potential in high-temperature military camouflage applications against enemy radar and infrared detection.展开更多
The spontaneous conversion of muonium to antimuonium is an interesting charged lepton flavor violation phenomenon that offers a sensitive probe for potential new physics and serves as a tool to constrain the parameter...The spontaneous conversion of muonium to antimuonium is an interesting charged lepton flavor violation phenomenon that offers a sensitive probe for potential new physics and serves as a tool to constrain the parameter space beyond the Standard Model.The Muonium-to-Antimuonium Conversion Experiment(MACE)was designed to utilize a high-intensity muon beam,a Michel electron magnetic spectrometer,a positron transport system,and a positron detection system to either discover or constrain this rare process with a conversion probability of O(10^(-13)).This article presents an overview of the theoretical framework and a detailed description of the experimental design for muonium-to-antimuonium conversion.展开更多
A methodology for the reduction of radar cross section(RCS)of cambered platforms within the target airspace is presented,which utilizes a dual-polarized ultra-wide-angle artificial electromagnetic absorbing surface.By...A methodology for the reduction of radar cross section(RCS)of cambered platforms within the target airspace is presented,which utilizes a dual-polarized ultra-wide-angle artificial electromagnetic absorbing surface.By applying the theory of generalized Brewster complex wave impedance matching,five distinct unit cell designs are developed to attain more than95%absorption rate for dual-polarized incident waves within five angular ranges:0°-30°,30°-50°,50°-60°,60°-70°,and 70°-80°.To optimally reduce the RCS of a cambered platform,the five types of units can be evenly distributed on the surface based on the local incident angles of plane waves originating from the target airspace.As an illustrative example,the leading edge of an airfoil is taken into account,and experimental measurements validate the efficiency of the proposed structure.Specifically,the absorbing surface achieves more than 10 dB of RCS reduction in the frequency ranges from 5-10 GHz(about66.7%relative bandwidth)for dual polarizations.展开更多
The rapid advancement of 5G/6G communication and radar technology has exacerbated issues of electromagnetic wave(EMW)leakage,interference,and thermal management.Therefore,developing lightweight EMW absorbers that inte...The rapid advancement of 5G/6G communication and radar technology has exacerbated issues of electromagnetic wave(EMW)leakage,interference,and thermal management.Therefore,developing lightweight EMW absorbers that integrate strong absorption,broad bandwidth,and thermal stability is crucial.Herein,a 3D MXene sponge/NiFe@NC heterostructure with tunable pore architecture is constructed by pyrolyzing a polyurethane(PU)foam template uniformly coated with NiFe-decorated Ti_(3)C_(2)T_(x)MXene nanosheets.The resulting porous dielectric-magnetic network integrates interconnected MXene pathways with uniformly dispersed NiFe@NC nanoparticles,enabling a synergistic effect of dielectric-magnetic loss through conduction loss,dipole/interface polarization,and magnetic loss.Precise pore structure design enhances impedance matching and promotes multi-scattering and internal reflection of EMWs.Notably,an“EMW-pore matching”mechanism is proposed,whereby pore size governs the impedance matching at specific frequencies,enabling tunable absorption performance.The optimized absorber achieves a reflection loss(RL)of-67.84 dB,while radar cross-section(RCS)simulations confirm its exceptional attenuation and stealth potential.Additionally,the 3D skeleton derived from PU foam confers remarkable thermal resistance and flame retardancy.This pore-regulation strategy provides a scalable route to designing lightweight,broadband,and thermally stable EMW absorbers for next-generation communication and stealth applications.展开更多
基金Project(2018YFC0807802)supported by the National Key R&D Program of ChinaProject(41874081)supported by the National Natural Science Foundation of China。
文摘A novel method for source effect correction based on integral equation method is proposed.By taking the electrical horizontal field Ex of current source as an example,the correction method is validated using both simulated data and field data.The results show that the correction method is feasible and effective for isotropic media.When the field data are processed,the correction method normalizes the sources with different geological structures,which eliminates the geological difference among sources,and retains the geological difference among receivers.The correction results are in line with the expectation in whole.
文摘This paper summarizes a theoretical design analysis for the implementation of an electromagnetic modeling tool, focusing on the simulation of electromagnetic field propagation inside reverberation chambers. The simulation algorithms which have been developed rely on a ray tracing technique, adapted in such a way as to maximize compatibility with the specific requirements and parameters, as applicable for reverberation chambers. The most significant example of a typical parameter is the high rate of wave reflections inside the chambers’ cavity. An implementation of the algorithms was used for simulation of several theoretically predictable cases. Study of the results of these test cases showed that some of the design decisions and algorithms used need to be reviewed in order to optimize the computational aspects of the application, such as resource management (memory, CPU time). Results of typical sample cases are re- viewed in this paper as well, in order to identify possible pitfalls and objectives for future research.
基金Item Sponsored by 111 project (B07015) the National Natural Science Foundation of China and Shanghai Baosteel (No.50834010) +1 种基金the Fundamental Research Funds for the Central Universities (N100409007) the Doctor Startup Foundation of Liaoning Province (20111009)
文摘Based on an analogy among the governing equations among the electrostatic field,static magnetic field and fluid flow,all these equations can be expressed by a general differential equation,and the control volume method,which has been widely used in computational fluid dynamics,was developed to solve all these equations.Numerical results showed that control volume method is a successful numerical in the computational fluid dynamics and the electromagnetics,and the upwind(or downwind)scheme have the clear mathematical meaning and can be applied to calculate the charges' movement in the electrostatic field.
基金partially supported by the National R & D Special Fund of Public Welfare Industry(No.200808069)National Natural Science Foundation of China(Nos.40974038 and 41025014)the Joint Research Collaboration Program by the Ministry of Science and Technology of China(No.2010DFA21570)
文摘We investigated how density and quality of mesh around interest domain affect electromagnetic （EM） responses of 3D Earth layered media using finite element method （FEM）. Effect of different mesh shapes was also investigated using a method of mixing structured and unstructured mesh. As a case study, we estimated the effects of meshing on selectivity phenomenon of seismic electric signal （SES）. Our results suggest that the relative errors resulting from mesh effects may not be negligible, which may lead to some unconvincing explanation of the SES selectivity based on the numerical modeling results.
文摘This paper summarizes recent research findings concerning centrioles, centriole duplication, centriole overduplication, supernumerary centrioles, centrosomes, and centrosome amplification. The paper then discusses the status of ongoing research on the use of nanoparticles for cancer treatment. The research findings show that a centriole produces an electromagnetic field apparently due to the longitudinal oscillation of its microtubules (MTs). A cluster of centrioles is therefore presumed to produce an enhanced electromagnetic field. Individual centrioles are immersed in a cloud of electron-dense material (proteins) which together with the centrioles is known as the centrosome. A cluster of centrioles thus produces a cluster of centrosomes—a hallmark of cancer cells. With enhanced electromagnetic fields, centrosome clusters provide an attraction for magnetically charged nanoparticles. These nanoparticles however are not attracted to normal cells which with only two (or at most four) centrioles, have a weaker magnetic field. The idea is simple: Magnetized and therapeutic nanoparticles are directed toward tumors and then attracted to the centrosome clusters of the tumor cells. Once inside the tumor cells, the nanoparticles can release their toxins.
文摘A class of finite step iterative methods, conjugate gradients, for the solution of an operator equation, is presented on this paper to solve electromagnetic scattering. The method of generalized equivalent circuit is used to model the problem and then deduce an electromagnetic equation based on the impedance operator. Four versions of the conjugate gradient method are presented and numerical results for an iris structure are given, to illustrate convergence properties of each version. Computational efficiency of these methods has been compared to the moment method.
文摘This paper research is the first part of the scientific theory that seeks to unify the sciences of physics with the minimal number of mathematical formulas as possible. We will prove that all equations of forces in nature can be concised in two mathematical formulas, no difference between gravitational or electrical forces or any other type of Types of conventional forces, and through the equivalence of the concepts of matrix and vector, in this theory we will be linking the four-dimensional forces equations with the classical physics as an introduction to connect the rest of the physical sciences.
基金supported by the National Natural Science Foundation of China(Grant Nos.62174086,62474096,62371255,and 62288102)the Outstanding Youth Foundation of Jiangsu Province(Grant No.BK20240139)the Basic Research Program of Jiangsu(Grant No.BK20243057),and the Qinglan Project of Jiangsu Province of China.
文摘Flexible electromagnetics,as an emerging and interdisciplinary field,integrates traditional electromagnetic functions such as the transmission,radiation,receiving,and processing of electromagnetic waves with advanced flexible electronic technol-ogies.This integration overcomes the inherent limitations of traditional rigid electromagnetic devices,thereby significantly expanding the applicability of electromagnetic technology in complex environments.It provides new research avenues and directions for the application of electromagnetic technology in cutting-edge fields such as smart healthcare,artificial intelligence,and aerospace.This paper provides a comprehensive overview of recent advancements in flexible electromagnetics from four key aspects:materials,de-vices,integration,and applications.Firstly,we provide a succinct introduction to flexible electromagnetic materials including metallic materials,inorganic nonmetallic materials,polymer materials,and composite materials.Then,we explore the development status of flexible electromagnetic devices such as antennas,radio frequency resonators,and electromagnetic shielding devices.Furthermore,we survey the advancements and applications of flexible electromagnetic integrated system in the fields of intelligent medical treat-ment and intelligent information perception.Finally,we summarize the current challenges in the field of flexible electromagnetics and provide a preliminary outlook on future development trends.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23B2015 and 62288101)the Fundamental Research Funds for the Central Universities(Grant No.2242023K5002)the 111 Project(Grant No.111-2-05)。
文摘Transformation optics(TO)or transformation acoustics(TA)theory provides an elegant framework for designing intricate wavematerial interaction devices.Combining TO or TA with emerging metamaterial technology,the propagating waves inside metamaterials can be guided at will by mapping a preset spatial pattern onto a specific constituent parameter distribution,thus achieving desired functionalities.In this review,we mainly focus on recent progress in TO and TA,in terms of basic theory and representative applications.Firstly,we introduce the fundamental principles of TO and TA.Subsequently,we present some related spatial-transformation-based applications in electromagnetics,such as cloaks,beam manipulation devices and applications in nonlinear responses,and some typical applications in acoustics,namely underwater ultrasound invisibility,sound imaging lenses and parity-time symmetry.Furthermore,we discuss transformation-based devices for acoustic-electromagneticjoint control.Finally,we summarize current spatial-transformation-based wave modulations and outline some future opportunities in this research field.
基金This work was supported by the National Basic Research Program of China （973 Program） （No. 2013CBA01700） and the National Natural Science Foundation of China （Grant No. 61138002）.
文摘Subwavelength electromagnetics is a disci- pline that deals with light-matter interaction at subwave- length scale and innovative technologies that control electromagnetic waves with subwavelength structures. Although the history can be dated back to almost one hundred years ago, the flourish of these researching areas have been no more than 30 years. In this paper, we gave a brief review of the history, current status and future trends of subwavelength electromagnetics. In particular, the milestones related with metamaterials, plasmonics, meta- surfaces and photonic crystals are highlighted.
基金Supported by the National Natural Science Foundation of China(22378181).
文摘The development of materials with excellent microwave absorption(MWA)and electromagnetic interference(EMI)shielding performances has currently received attention.Herein,mesophase pitch-based carbon foam(MPCF)with 3D interconnected pore structure was prepared through the high pressure pyrolysis of mesophase coal tar pitch.It is found that the 3D interconnected cellular pores of MPCF facilitate multiple reflections of electromagnetic waves,which results in the minimum reflection loss(RLmin)value of MPCF reaches-37.84 dB with the effective absorption bandwidth(EAB)of 5.44 GHz at a thickness of 2.70 mm,and the total average electromagnetic shielding effectiveness(SE_(T))under 3.00 mm thickness achieves 26.52 dB in X-band.Subsequently,MPCF is activated by KOH to obtain activated carbon foam(A-MPCF).The average SE_(T)of A-MPCF achieves 103.00 dB for abundant nanopores on the pore cell walls,which leads to a transition from the multiple reflections of electromagnetic waves on the walls to diffuse reflection.Unfortunately,the reflection coefficient(R)of A-MPCF increases from 0.78 to 0.90.To reduce the R value,Fe_(3)O_(4)/A-MPCF was fabricated via the in situ growth of nano Fe_(3)O_(4)on A-MPCF.Consequently,the R value of Fe_(3)O_(4)/A-MPCF was reduced from 0.90 to 0.74,whereas the MWA performance was only slightly decreased.This work proposes a simple strategy for simultaneously adjusting MWA and EMI shielding performances of materials.
文摘This study investigates prescribed-time position tracking control for electromagnetic satellite formations subject to model uncertainties and external disturbances.Using the Clohessy-Wiltshire equations as the relative motion dynamics model,a prescribed time output feedback control strategy is proposed.A prescribed-time extended state observer is designed to estimate the relative velocity and external disturbances.The disturbance estimates are then used as the feedforward component of the controller.Building on this framework,a novel prescribed-time active disturbance rejection control strategy for position tracking is developed via a backstepping control design.The convergence of the extended state observer and the stability of the closed-loop system are rigorously analyzed using Lyapunov stability theory.Numerical simulations are performed to validate the effectiveness of the proposed controller.
文摘The multi-satellite electromagnetic formation flight system is nonlinear and strongly coupled,which makes modeling and optimization challenging.To simplify electromagnetic force evaluation and dynamics modeling,we introduce a reference frame consistent with each satellite body frame,in which the electromagnetic dipoles and electromagnetic forces are represented as two-dimensional vectors.Then,the maneuver time is divided into time intervals,and different satellite sets are activated in each interval,converting the multi-satellite formation reconfiguration problem into an optimal trajectory problem of each two-satellite subsystem.To this end,a token-based dynamic programming method with a switching penalty of active satellite sets is proposed to determine the sequence of satellite sets participating in each time interval,thereby enabling all satellites to reach their desired states.For the two-satellite subsystem with the objectives of minimizing maneuver time and energy consumption,the Gauss pseudo-spectral method is employed to generate the optimal reconfiguration trajectory.Numerical simulations verify the effectiveness of the proposed optimization method.
基金Project supported by the National Natural Science Foundation of China(No.61971335).
文摘While many techniques have been developed for the design of different types of antennas,such as wire antenna,patch antenna,lenses,and reflectors,these cannot be said general-purpose strategies for the synthesis and design of antennas to achieve the performance characteristics specified by users.Recently,there has been an increasing need for the development of antenna design techniques because of the advent of 5 G and a variety of space,defense,biological,and similar applications,for which a robust and general-purpose design tool is not to be developed.The main objective of this study is to take a look at antenna design from the field manipulation point of view,which has the potential to partially fulfill this need.We review the existing field manipulation techniques,including field transformation methods based on Maxwell’s and wave equations,point out some limitations of these techniques,and then present ways to improve the performance of these methods.Next,we introduce an alternative approach for field manipulation based on two-dimensional(2 D)metasurfaces,and present laws of the generalized reflection and refraction that are based on 2 D surface electromagnetics.Then,we explore how to overcome the limitations of conventional reflection and refraction processes that are strictly bounded by the critical angle.Finally,we provide some application examples of field manipulation methods in the antenna design,with a view on developing a general-purpose strategy for antenna design for future communication.
基金support provided by the Center for Fabrication and Application of Electronic Materials at Dokuz Eylül University,Türkiye。
文摘Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2024QE446)。
文摘With the rapid development of intelligent electronic and military equipment,multifunctional flexible materials that integrat electromagnetic interference(EMI)shielding,temperature sensing,and information encryption are urgently required.This study presents a bio-inspired hierarchical composite foam fabricated using supercritical nitrogen foaming technology.This material exhibits a honeycomb structure,with pore cell sizes controllable within a range of 30–92μm by regulating the filler.The carbon fiber felt(CFf)provides efficient reflection of electromagnetic waves,while the chloroprene rubber/carbon fiber/carbon black foam facilitates both wave absorption and temperature monitoring through its optimized conductive network.This synergistic mechanism results in an EMI shielding effectiveness(SE)of 60.06 d B with excellent temperature sensing performance(The temperature coefficient of resistance(TCR)is-2.642%/℃)in the 24–70℃ range.Notably,the material has a thermal conductivity of up to 0.159 W/(m·K),and the bio-inspired layered design enables information encryption,demonstrating the material's potential for secure communication applications.The foam also has tensile properties of up to 5.13 MPa and a tear strength of 33.02 N/mm.This biomimetic design overcomes the traditional limitations of flexible materials and provides a transformative solution for next-generation applications such as flexible electronics,aerospace systems and military equipment,which urgently need integrated electromagnetic protection,thermal management and information security.
基金the financial support from China Postdoctoral Science Foundation(2024M760348)National Natural Science Foundation of China(52373077)。
文摘Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based nonwoven fabric(PFN_y)is prepared by alkali treatment,Fe~(3+)ion exchange,thermal reduction,and electroless nickel(Ni)plating process.Its impedance/insulation characteristics can be easily adjusted by controlling the in situ growth of Fe_(3)O_(4) and electroless nickel plating.Subsequently,a new strategy of constructing hierarchical dual-gradient impedance/insulation structure is implemented to achieve EMI shielding,radar and infrared stealth via stacking PFN_y with gradually decreased impedance/insulation characteristics from top to bottom.The formation of impedance matching gradient structure promotes effective introduction and dissipation of electromagnetic waves,endowing the composite with outstanding EMI shielding and radar stealth performance.Meanwhile,the construction of thermal insulation gradient structure can effectively inhibit thermal radiation from target,bringing an excellent infrared stealth performance.Importantly,the strong interfacial interactions between Fe_(3)O_(4),Ni and polyimide fiber accelerate PFNy to resist the stresses originated from high-temperature heat source,achieving a compatible high-temperature resistant radar/infrared stealth performance.Such excellent comprehensive properties endow it with a great potential in high-temperature military camouflage applications against enemy radar and infrared detection.
基金supported by National Natural Science Foundation of China(Nos.12075326,11535014,11975017,12475191,11905092,12105132 and 12175039)Guangdong Basic and Applied Basic Research Foundation(No.2025A1515010669)+7 种基金Natural Science Foundation of Guangzhou(No.2024A04J6243)Fundamental Research Funds for the Central Universities(23xkjc017)in Sun Yat-sen UniversityBasic Research Conditions and Major Scientific Instrument and Equipment Research and Development Projects of the Ministry of Science and Technology(No.2022YFF0705602)the State Key Laboratory of Particle Detection and Electronics(SKLPDE-ZZ-202412)Natural Science Foundation of Shandong Province(No.2023HWYQ-010)the“Fundamental Research Funds for the Central Universities”at Southeast Universitythe National Development and Reform Commission of China(Large Research Infrastructures of 12th Five-Year Plan:China initiative Accelerator Driven System)(No.2017-000052-75-01-000590)Innovation Training Program for bachelor students in Sun Yat-sen University。
文摘The spontaneous conversion of muonium to antimuonium is an interesting charged lepton flavor violation phenomenon that offers a sensitive probe for potential new physics and serves as a tool to constrain the parameter space beyond the Standard Model.The Muonium-to-Antimuonium Conversion Experiment(MACE)was designed to utilize a high-intensity muon beam,a Michel electron magnetic spectrometer,a positron transport system,and a positron detection system to either discover or constrain this rare process with a conversion probability of O(10^(-13)).This article presents an overview of the theoretical framework and a detailed description of the experimental design for muonium-to-antimuonium conversion.
基金supported by the National Key Research and Development Program of China(2023YFB3907304-3)the National Natural Science Foundation of China(NSFC)(62271050)。
文摘A methodology for the reduction of radar cross section(RCS)of cambered platforms within the target airspace is presented,which utilizes a dual-polarized ultra-wide-angle artificial electromagnetic absorbing surface.By applying the theory of generalized Brewster complex wave impedance matching,five distinct unit cell designs are developed to attain more than95%absorption rate for dual-polarized incident waves within five angular ranges:0°-30°,30°-50°,50°-60°,60°-70°,and 70°-80°.To optimally reduce the RCS of a cambered platform,the five types of units can be evenly distributed on the surface based on the local incident angles of plane waves originating from the target airspace.As an illustrative example,the leading edge of an airfoil is taken into account,and experimental measurements validate the efficiency of the proposed structure.Specifically,the absorbing surface achieves more than 10 dB of RCS reduction in the frequency ranges from 5-10 GHz(about66.7%relative bandwidth)for dual polarizations.
基金supported by the National Natural Science Foundation of China(52562043)Jiangxi Provincial Natural Science Foundation(20244BAB28050)。
文摘The rapid advancement of 5G/6G communication and radar technology has exacerbated issues of electromagnetic wave(EMW)leakage,interference,and thermal management.Therefore,developing lightweight EMW absorbers that integrate strong absorption,broad bandwidth,and thermal stability is crucial.Herein,a 3D MXene sponge/NiFe@NC heterostructure with tunable pore architecture is constructed by pyrolyzing a polyurethane(PU)foam template uniformly coated with NiFe-decorated Ti_(3)C_(2)T_(x)MXene nanosheets.The resulting porous dielectric-magnetic network integrates interconnected MXene pathways with uniformly dispersed NiFe@NC nanoparticles,enabling a synergistic effect of dielectric-magnetic loss through conduction loss,dipole/interface polarization,and magnetic loss.Precise pore structure design enhances impedance matching and promotes multi-scattering and internal reflection of EMWs.Notably,an“EMW-pore matching”mechanism is proposed,whereby pore size governs the impedance matching at specific frequencies,enabling tunable absorption performance.The optimized absorber achieves a reflection loss(RL)of-67.84 dB,while radar cross-section(RCS)simulations confirm its exceptional attenuation and stealth potential.Additionally,the 3D skeleton derived from PU foam confers remarkable thermal resistance and flame retardancy.This pore-regulation strategy provides a scalable route to designing lightweight,broadband,and thermally stable EMW absorbers for next-generation communication and stealth applications.
