Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport prope...Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport properties is crucial for TE technology,in which magnetism has provided a new degree of freedom in decoupling electron and phonon transports.This paper provides a comprehensive overview of recent advancements in magnetics-induced enhancement for both longitudinal and transverse TE systems.Initially,two key optimization strategies for longitudinal TE power generation are explored:enhancing non-magnetic TE performance in intrinsic magnetic materials and optimizing magnetic TE performance by utilizing extrinsic magnetism-induced effects.Following this,the mechanism by which external magnetic fields enhance transverse TE conversion is explained in detail.Moreover,we discuss in depth how magnetism influences the electron and phonon transports from a physical perspective.Finally,the promising applications of magnetics-induced TE technology in both power generation and solid-state cooling are discussed,with some key challenges being proposed.展开更多
In this work,we develop a novel computational method,referred to as SCT-Z-FDTD,which integrates the Z-transform finite-difference time-domain algorithm with a scale-compressed technique incorporating wave vectors.The ...In this work,we develop a novel computational method,referred to as SCT-Z-FDTD,which integrates the Z-transform finite-difference time-domain algorithm with a scale-compressed technique incorporating wave vectors.The proposed approach fa-cilitates accurate modeling of electromagnetic wave propagation through multi-layered anisotropic media,enabling precise evalua-tion of reflection and refraction coefficients over short time intervals.On first place,considering constitutive relationship between electromagnetic fields(E,H)and fluxes(D,B),Z-transform is employed to the anisotropic Maxwell’s curl equations for completing discrete-time form,and then the transverse wave vectors are exploited along a single direction to design the electromagnetic numerical differential process.After that,with the analysis corresponding flow chart,the plane waves are employed with different modes such as transverse electromagnetic,transverse electric,and transverse magnetic to detect the specific propagation.To further verify lower memory and higher efficiency,we select various multi-layered examples with anisotropies for executing the proposed method.Compared with the popular commercial software COMSOL,those data from multi-layered computation are quite consistent with the approximate trend the 2nd-order error convergence.展开更多
Recent explorations and advancements in communications systems have sparked a renewed fascination with beamsteerable high-gain antennas.While conventional active phased arrays have been long seen as a feasible solutio...Recent explorations and advancements in communications systems have sparked a renewed fascination with beamsteerable high-gain antennas.While conventional active phased arrays have been long seen as a feasible solution,the associated cost is a major impediment for electrically large millimeter-wave apertures.In this paper,we present an all-metal metamaterial-loaded Huygens box antenna that facilitates independent steering of radiation in azimuth and elevation directions and a dramatic reduction in the number of phased elements.The antenna encloses an artificial dielectric medium with an active Huygens metasurface arranged around the enclosure’s periphery.We present simulation and experiment results for a representative square aperture,where is the free-space wavelength.The results show that the antenna radiates similarly to a phased array of similar aperture size,with a quadratic-to-linear reduction ratio in the number of required elements,leading to over 10-fold reduction for large-aperture antennas.The tremendous reduction in the number of excited elements positions the antenna as a cost-saving alternative,especially in large aperture millimeter-wave regime.展开更多
Domain decomposition method(DDM)is one of the most efficient and powerful methods for solving extra-large scale and intricate electromagnetic(EM)problems,fully embodying the divide-and-conquer philosophy.It provides t...Domain decomposition method(DDM)is one of the most efficient and powerful methods for solving extra-large scale and intricate electromagnetic(EM)problems,fully embodying the divide-and-conquer philosophy.It provides the strategy of dealing with a computationally huge task that is not easy to be solved directly—dividing the task into a number of smaller ones,i.e.sub-tasks,each can be readily solved independently and employing appropriate transmission conditions(TCs)accounting for the interactions communication among these sub-tasks.This paper presents a comprehensive overview of DDM,highlighting its fundamental principles and wide-ranging applications in many diverse areas,such as very-large-scale integration circuits,antenna array radiation,and wave scattering.In the evolution of this technology,DDM has gradually manifested its remarkable power of tackling complex EM problems through its merging with Laplace,wave,Maxwell equations,as well as surface integral equations and volume integral equations.The further evolved advanced algorithms such as overlapped DDM and non-overlapped DDM are also reviewed.The efficiency of the DDMs depends strongly on the TCs of EM fields at the interface among adjacent sub-domains.The diversity of TCs in differential and integral equations generates a variety of DDMs.Due to the independence of sub-domains,the DDMs are inherently well-suited for parallel processing with high flexibility,making them particularly effective for EM full-wave simulations on distributed computers.Finally,a list of remaining challenging technical issues and future perspective on the fast-evolving field will be provided.展开更多
Antennas are essential components of any wireless system due to their irreplaceable functions in transmitting and receiving electromagnetic waves.Antenna radiation is based on the free electron resonance,leading to a ...Antennas are essential components of any wireless system due to their irreplaceable functions in transmitting and receiving electromagnetic waves.Antenna radiation is based on the free electron resonance,leading to a concrete relation between its physical size and operating frequency.This fundamental principle makes it unrealizable to design well-radiated antennas with extremely small dimensions,e.g.,milli-wavelength scales.Here,to overturn this commonsense correlation,an extremely miniaturization methodology of antennas is developed by integrating an arbitrary-sized antenna with an ohmic-biased transistor(OBT)circuit.In this way,we thousandfold miniaturize the antenna to an overall size at milli-wavelength scales,including the OBT circuits.Proven by the experiments in the demonstration systems,the wireless system with this thousandfold miniaturized antenna receives electromagnetic waves well.This methodology would be widely utilized in space-limited wireless systems that cannot provide enough space for antennas,benefiting various exciting areas,such as information technologies,photoelectricity physics,biomedical science,and so on.展开更多
Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological explor...Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological exploration,featuring both hardware module integration and data processing methods.The hardware module incorporates a multi-rotor drone,a cesium optically pumped magnetometer,and a synchronized data acquisition system for processing magnetic and GPS position data.It can rapidly measure the magnetic field of the archaeological sites to capture the magnetic anomaly signals.The data processing methods consist of diurnal variation correction,survey line correction,aeromagnetic noise suppression,and a leveling algorithm based on curvelet transform,which is capable of identifying magnetic anomaly signals within the measured magnetic field.Field tests were conducted at the Song Dynasty iron smelting site in Xiacaopu,Anxi County,Fujian Province,China,where the system successfully discovered a new smelting furnace relic,which was subsequently confirmed through excavation.展开更多
Integrated photonic gyroscopes(IPGs)have emerged as a promising alternative to other gyroscopes,providing high sensitivity,compactness,and low power consumption,especially being more conducive to integration.In this r...Integrated photonic gyroscopes(IPGs)have emerged as a promising alternative to other gyroscopes,providing high sensitivity,compactness,and low power consumption,especially being more conducive to integration.In this review,we discuss recent advances in IPG technology and research,including the different types of IPGs currently being developed,such as waveguide spiral-based,ring laser gyroscope,and passive ring resonator based IPGs.We highlight the efforts dedicated to improve the stability,accuracy,and resolution of IPGs,such as using narrow-band laser diodes and using a high-stability,low-noise power supply system.Additionally,we provide an overview of the key performance measures of IPGs,including resolution,drifting,stability,noise cancellation as well as their interrelationships.Finally,we discuss challenges and future directions for the IPG research,including improving long-term stability and addressing sensitivity to shock and vibrations.展开更多
The rapid proliferation of Internet of things(IoT)devices has driven an unprecedented demand for efficient multi-user communication solutions.Traditional methods for multiplexing,such as frequency-division and code-di...The rapid proliferation of Internet of things(IoT)devices has driven an unprecedented demand for efficient multi-user communication solutions.Traditional methods for multiplexing,such as frequency-division and code-division multiplexing,are struggling to accommodate the increasing number of users and the limited spectrum resources available.To address these chal-lenges,this paper presents an innovative wireless communication system that leverages reconfigurable intelligent surface(RIS)and orbital angular momentum(OAM)technologies to enhance spectral efficiency,reduce interference,and meet the high data rate re-quirements of modern IoT applications.The proposed system integrates a multi-mode OAM transmitter to generate signals carrying multiplexed data streams,which are subsequently directed to a metasurface-based RIS.The RIS is designed to receive the incident OAM beams,demultiplex the data,and focus it in real-time to distinct spatial regions,achieving a high signal-to-noise ratio(SNR)and minimizing interference for efficient multi-user transmission.A practical 2-bit transmissive RIS design is employed,which en-ables dynamic control over OAM modes,focusing energy at different user locations in the near-field,thereby realizing flexible and independent control of each unit.To generate the multi-mode OAM beams,a simplified microstrip antenna working at 10 GHz is utilized,incorporating a multi-layer printed circuit board(PCB)isolation design to minimize coupling interference between modes,ensuring reliable and efficient mode generation.To validate the effectiveness of the proposed system,we conduct full-wave simula-tion experiments,and build a complete communication testing environment,covering the entire communication process from the multi-mode OAM transmitter to the RIS-based communication link.Experimental results demonstrate that the proposed solution can effectively achieve near-field spot-beam focusing through the RIS and enable multi-user,same-frequency data separation at each fo-cal point.This provides a novel and efficient solution for high-spectral-efficiency,low-interference multi-user data interaction in IoT networks,offering new insights for enhancing multi-user access and data transmission efficiency in various IoT scenarios,including smart factories,logistics centers,and in-vehicle communications.展开更多
The design of nonuniform transmission line impedance transformers is demonstrated by applying a convex optimization method.A constrained convex semidefinite relaxation problem is defined by minimizing the input reflec...The design of nonuniform transmission line impedance transformers is demonstrated by applying a convex optimization method.A constrained convex semidefinite relaxation problem is defined by minimizing the input reflection coefficient magnitude squared at a number of frequency values.Additional constraints on the minimum and maximum transmission line impedance values along the length of the line are imposed.The optimization process is demonstrated for real and complex loads.Such impedance transformers find broad applications in broadband impedance matching and balun design for antenna and amplifier circuits or rectifier circuits,for example in energy harvesting and wireless power transmission applications.展开更多
As foldable smartphones typically operate in two primary states—unfolded state and folded state,the structural changes between the two states,which can significantly impact antenna performance,such as frequency shift...As foldable smartphones typically operate in two primary states—unfolded state and folded state,the structural changes between the two states,which can significantly impact antenna performance,such as frequency shifts and efficiency reduction,are critical for practical applications.This paper proposes to use a quarter-wavelength parasitic branch to mitigate the effect of the structural changes between the two states.With the quarter-wavelength parasitic branch,a high-efficiency deca-band mobile antenna with similar performance in both the unfolded and folded states is achieved.Prototype testing shows negligible frequency shifts(approximately 0 MHz)in the low band(LB)of 0.704–0.960 GHz,middle high band(MHB)of 1.71–2.69 GHz,and new radio(NR)bands of 3.3–3.8 GHz and 4.7–5.0 GHz between the unfolded and folded states.The efficiency reductions are 0.45 dB(from−4.98 dB to−5.43 dB)in the LB band,0.28 dB(from−2.70 dB to−2.98 dB)in the MHB band,and 0.81 dB(from−2.34 dB to−3.15 dB)in the NR band.The proposed antenna,which demonstrates minimal frequency shifts and slight efficiency degradation in the unfolded and folded states,makes it highly promising for practical applications.展开更多
The future of wireless systems is anticipated to revolutionize human connectivity through a diverse range of applications.The integration of multiple wireless functionalities into a unified system presents a critical ...The future of wireless systems is anticipated to revolutionize human connectivity through a diverse range of applications.The integration of multiple wireless functionalities into a unified system presents a critical challenge due to conflicting requirements in transceiver architecture and signal processing.Recent investigations are directing attention towards the development of systems that serve dual functions,like simultaneous wireless information and power transfer and radar-communication,aimed at boosting operational efficiency and ensuring seamless communication among different wireless capabilities.This review paper aims to discuss the architectural aspects of the integration of radar sensing,data communication,and power transfer.Firstly,the integration of radar sensing and data communication is studied for both cooperating and non-cooperating radar systems with conventional and interferometric architectures.Secondly,the power harvesting approach and internal energy recycling are discussed for the fusion of data communication and energy harvesting.Thirdly,radar sensing and power transfer integration is considered with special focus on harmonic backscattering and self-powered radars.Lastly,a roadmap for next-generation multifunction systems is outlined by considering several scenarios of multiplexing and architectures.展开更多
Massive multiple-input multiple-output(MIMO)and intelligent reflecting surface(IRS)technologies have become a research focus for non-stationary vehicle-to-vehicle(V2V)wireless communications due to their capability to...Massive multiple-input multiple-output(MIMO)and intelligent reflecting surface(IRS)technologies have become a research focus for non-stationary vehicle-to-vehicle(V2V)wireless communications due to their capability to control radio propagation environment.In this paper,a non-stationary irregular geometry-based stochastic model(I-GBSM)for V2V massive MIMO systems using three-dimensional uniform linear arrays and discrete IRS at millimetre-wave operating frequencies is proposed.A new approach for determining IRS elements phase-shift using the Doppler effect and channel impulse response is introduced to mitigate channel non-stationarity and enhance propagation conditions.Unlike traditional models,it takes into account practical spherical wavefronts instead of plane wavefronts.The proposed model categorizes clusters into moving and static clusters to examine traffic density and its effects on channel characteristics in V2V environments.It employs a novel birth-death process to ensure consistency in cluster evolution.The non-stationary stochastic channel characteristics are comprehensively analyzed through simulations.These characteristics include space-time-frequency correlation functions,Doppler power spectral density,path loss,delay spread,root mean square error of the correlation function,and achievable rate across different operating frequencies.The analysis demonstrates notable performance improvements.The proposed I-GBSM is also validated by a good agreement with the results from existing models and measurements under reduced scenarios.展开更多
The rapid and accurate identification of biological tissue types in resected specimens is critical to ensure complete tumor excision during surgery.By leveraging inherent electromagnetic property variations among tiss...The rapid and accurate identification of biological tissue types in resected specimens is critical to ensure complete tumor excision during surgery.By leveraging inherent electromagnetic property variations among tissues,this study presents a novel dual-port electromagnetic method that employs two-port S-parameters for quantitative tissue discrimination.The proposed technology leverages differences in the broadband electromagnetic properties among biological tissues,which are manifested as distinct attenu-ation characteristics during signal transmission.This approach allows for the successful differentiation of various tissue types,such as skin,muscle,fat,and tumor tissues,in ex vivo tumor-bearing mouse models.Specifically designed for biological tissue detection,this dual-port framework is the first to achieve a calibration-free operation and facilitate the detection of tumors with a size as small as 0.1 mm.Experimental validation in tumor-bearing mouse models demonstrated robust differentiation among skin,fat,muscle,and tumor tissues.Consistent measurements across multiple orientations were achieved,with a specific absorption rate below 0.0091 W/kg confirming operational safety.The transmission characteristics reveal significant bioelectromagnetic interactions,providing physical insights into tissue dielectric properties.This method provides a promising platform for clinical diagnostics and precision surgical guidance.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
For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equatio...For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equations for a mechano-driven media system(MEs-f-MDMS).Here,by defining the effective electric and magnetic fields,the MEs-f-MDMS reduces to the stand-ard form of the Maxwell’s equations(MEs)in some engineering scenarios.This means that the accelerated motion of a medium is a source for generating electromagnetic wave,while the propagation of the waves in the system follows the classical MEs.Therefore,the standard methods for solving the MEs can be adequately applied.We first present the theoretical derivation,then we will present the solutions of the MEs-f-MDMS in both time-and frequency-space.Second,the shortcomings in classical approach regarding to the calculation of electromagnetic radiation from a rotating medium is analyzed.Third,the theory about the impact of medium rota-tion on reflection and transmission of a plane wave at an interface is considered.Fourth,the theory for quantifying the output of tri-boelectric nanogenerator is given.Fifth,since the effective fields warrant the covariance of the MEs,the Lorentz transformation can be introduced for extrapolating the effective field theory to a case there is a translation motion of the system with considering rela-tivistic effect.Finally,recent progresses about the experimental proofs in supporting the MEs-f-MDMS are covered.展开更多
In this article,we propose a novel super-resolution method for ultrawideband radar imaging,to address the problem of degraded range estimation accuracy of off-grid targets.We propose generalized atomic norm minimizati...In this article,we propose a novel super-resolution method for ultrawideband radar imaging,to address the problem of degraded range estimation accuracy of off-grid targets.We propose generalized atomic norm minimization(ANM)with modality demixing,dubbed ANM-MD,which effectively harnesses the sparsity of radar targets over a continuous range space.First,we demix the radar echo of targets according to their frequency dependency modalities(FDMs)in the geometrical theory of diffraction model.By modality demixing,we can suppress the influence of multiple FDMs on consequent estimation of target ranges.Then,we estimate the scattering parameters of radar targets separately in each FDM,leading to accurate estimation of target ranges.Experimental results show that our method can improve the accuracy of range estimation of off-grid targets by more than 15%compared with existing methods,leading to improved quality of super-resolution imaging.展开更多
Recent years have seen increased interest in optoelectronic semiconductor materials,particularly those from groups Ⅱ-Ⅵ,Ⅳ-Ⅵ,and perovskite,due to their outstanding electronic and optical properties.However,the toxi...Recent years have seen increased interest in optoelectronic semiconductor materials,particularly those from groups Ⅱ-Ⅵ,Ⅳ-Ⅵ,and perovskite,due to their outstanding electronic and optical properties.However,the toxicity and environmental concerns related to heavy metals like lead and cadmium have hindered their widespread commercial use,shifting the focus to AgBiS_(2),a nontoxic,cost-effective,and promising alternative.Despite significant progress,the efficiency of AgBiS_(2)remains lower than that of perovskite or cadmium-lead-based devices,primarily due to challenges in nanocrystals(NCs)synthesis and limitations in device structure and stability when using AgBiS_(2)thin films.This review evaluates these challenges by examining the synthesis process,addressing device-related limitations,and discussing recent advancements in AgBiS_(2)research and its potential applications.It includes an analysis of AgBiS_(2)’s chemical and crystal structures,as well as its optoelectronic properties.Additionally,we review improvements in synthesizing high-quality AgBiS_(2)NCs and discuss applications such as photodetectors and X-ray/photoelectrochemical sensors.Finally,we highlight the challenges and future prospects for AgBiS_(2),offering insights into its potential for various applications.展开更多
In this article,the ultra-efficient transfer matrix method(U-TMM)is developed to detecting the propagation coeffi-cients of ultra-multilayered anisotropic media(UMAM)in the terahertz region.Starting from the curl Maxw...In this article,the ultra-efficient transfer matrix method(U-TMM)is developed to detecting the propagation coeffi-cients of ultra-multilayered anisotropic media(UMAM)in the terahertz region.Starting from the curl Maxwell’s equations and combined with the constitutive relation,the governing equation can be described in matrix form from which the four eigenvalues are derived,so that each component of the electromagnetic field can be uniquely represented by the fixed formula.The core thought with U-TMM is to maintain tangential continuity of electromagnetic fields between different media,thereby constructing transfer matrix between various regions and achieving the calculation of propagation coefficients in UMAM.After successfully validating U-TMM through two numerical examples,we find that U-TMM compensates for the shortcomings of COMSOL software in dealing with the UMAM problems,and in addition,the computational efficiency is significantly improved compared to the conventional transfer matrix method.Finally,to verify the energy change process in UMAM,we generate color images of the propagation coeffi-cients by U-TMM in transverse electric/transverse magnetic mode,which can be applied to the analysis for materials and devices in the terahertz region.展开更多
With the increasing maturity of various computational electromagnetics algorithms,the field has evolved from traditional standalone electromagnetic simulations to a stage in which trustworthy electromagnetic computati...With the increasing maturity of various computational electromagnetics algorithms,the field has evolved from traditional standalone electromagnetic simulations to a stage in which trustworthy electromagnetic computation methods serve as the core,aimed at meeting the advanced demands of computer-aided engineering.Trustworthy electromagnetic computation consists of three key aspects:trustworthy model,trustworthy mesh,and trustworthy algorithm.This paper focuses on the aspect of trustworthy mesh,aiming to establish a systematic framework and methodology for achieving trustworthy computation under the assumption that the target geometry and associated parameters are determined.The framework starts with high-fidelity geometric meshing.An effective strategy is nonconformal domain decomposition,which facilitates accurate modeling of complex geometries and diverse materials.Subsequently,efficient preconditioning methods are utilized to ensure stable convergence when solving the resulting multiscale systems associated with high-fidelity meshes.After obtaining the numerical solution,verification procedures are applied to evaluate whether the desired accuracy has been achieved.If the solution fails to meet the specified precision,adaptive mesh refinement techniques are used to automatically redistribute mesh density.The objective is to attain greater accuracy with a minimal increase in degrees of freedom,thereby enhancing computational efficiency.The adaptive refinement process proceeds iteratively until the computed solution satisfies the established accuracy criteria.Within this framework,we propose a novel,fast,physics-based self-reference method,which leverages power conservation laws to assess the accuracy of the solution.展开更多
Microwave photonics(MWP)represents a significant optical signal processing system,standing at the confluence of microwave engineering and photonics.It presents a promising way for meeting the growing demands of contem...Microwave photonics(MWP)represents a significant optical signal processing system,standing at the confluence of microwave engineering and photonics.It presents a promising way for meeting the growing demands of contemporary communication systems,radar,sensing,and signal processing.Driving the rapid advancement of MWP are pivotal technologies such as optical frequency combs,photonic integrated circuits,and advanced modulation formats.The integration of photonic integrated circuit technology with hybrid integration techniques holds the promise of realizing MWP systems on a single chip,while comb shaping technology endows MWP systems with programmable and reconfigurable capabilities.In this paper,we present a review of our recent research,which focused on exploring the full spectrum of potential applications for quantum dash lasers in MWP systems.Leveraging principles of finite impulse response filters,our MWP system not only facilitates conventional filtering but also enables instantaneous frequency measurement and waveform generation.A distinguishing feature of MWP filters is their uniform delay.After converting it into a uniform phase difference,it underpins the development of MWP-based phase antenna array systems.Furthermore,this uniform delay finds application in time-interleaved photonic analog-to-digital conversion.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.52525101)the Tencent Xplorer Prize,the National Natural Science Foundation of China(Grant Nos.52450001 and 22409014)+3 种基金the International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52411540237)the Beijing Natural Science Foundation(Grant No.JQ18004),and the 111 Project(Grant No.B17002)Bingchao Qin acknowledges support from the China National Postdoctoral Program for Innovative Talents(Grant No.BX20230456)China Postdoctoral Science Foundation(Grant No.2024M754057).
文摘Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport properties is crucial for TE technology,in which magnetism has provided a new degree of freedom in decoupling electron and phonon transports.This paper provides a comprehensive overview of recent advancements in magnetics-induced enhancement for both longitudinal and transverse TE systems.Initially,two key optimization strategies for longitudinal TE power generation are explored:enhancing non-magnetic TE performance in intrinsic magnetic materials and optimizing magnetic TE performance by utilizing extrinsic magnetism-induced effects.Following this,the mechanism by which external magnetic fields enhance transverse TE conversion is explained in detail.Moreover,we discuss in depth how magnetism influences the electron and phonon transports from a physical perspective.Finally,the promising applications of magnetics-induced TE technology in both power generation and solid-state cooling are discussed,with some key challenges being proposed.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.62101333)the Program for Excellent Scientific and Innovation Research Team(Grant No.2022AH010002)the 2024 Anhui Province University Science and Engineering Teachers’Internship Program in Enterprises(Grant No.2024jsqygz02).
文摘In this work,we develop a novel computational method,referred to as SCT-Z-FDTD,which integrates the Z-transform finite-difference time-domain algorithm with a scale-compressed technique incorporating wave vectors.The proposed approach fa-cilitates accurate modeling of electromagnetic wave propagation through multi-layered anisotropic media,enabling precise evalua-tion of reflection and refraction coefficients over short time intervals.On first place,considering constitutive relationship between electromagnetic fields(E,H)and fluxes(D,B),Z-transform is employed to the anisotropic Maxwell’s curl equations for completing discrete-time form,and then the transverse wave vectors are exploited along a single direction to design the electromagnetic numerical differential process.After that,with the analysis corresponding flow chart,the plane waves are employed with different modes such as transverse electromagnetic,transverse electric,and transverse magnetic to detect the specific propagation.To further verify lower memory and higher efficiency,we select various multi-layered examples with anisotropies for executing the proposed method.Compared with the popular commercial software COMSOL,those data from multi-layered computation are quite consistent with the approximate trend the 2nd-order error convergence.
基金supported by the Research Grants Council of Hong Kong(Grant Nos.CityU 21211619 and AoE/E-101/23-N)the CityU Strategic Resaerch Grant Fund(Grant No.7006088).
文摘Recent explorations and advancements in communications systems have sparked a renewed fascination with beamsteerable high-gain antennas.While conventional active phased arrays have been long seen as a feasible solution,the associated cost is a major impediment for electrically large millimeter-wave apertures.In this paper,we present an all-metal metamaterial-loaded Huygens box antenna that facilitates independent steering of radiation in azimuth and elevation directions and a dramatic reduction in the number of phased elements.The antenna encloses an artificial dielectric medium with an active Huygens metasurface arranged around the enclosure’s periphery.We present simulation and experiment results for a representative square aperture,where is the free-space wavelength.The results show that the antenna radiates similarly to a phased array of similar aperture size,with a quadratic-to-linear reduction ratio in the number of required elements,leading to over 10-fold reduction for large-aperture antennas.The tremendous reduction in the number of excited elements positions the antenna as a cost-saving alternative,especially in large aperture millimeter-wave regime.
基金supported by the National Natural Science Foundation of China(Grant Nos.62293492,62131008,and 62188102)the National Key Research and Development Program of China(Grant No.2024YFB2908601).
文摘Domain decomposition method(DDM)is one of the most efficient and powerful methods for solving extra-large scale and intricate electromagnetic(EM)problems,fully embodying the divide-and-conquer philosophy.It provides the strategy of dealing with a computationally huge task that is not easy to be solved directly—dividing the task into a number of smaller ones,i.e.sub-tasks,each can be readily solved independently and employing appropriate transmission conditions(TCs)accounting for the interactions communication among these sub-tasks.This paper presents a comprehensive overview of DDM,highlighting its fundamental principles and wide-ranging applications in many diverse areas,such as very-large-scale integration circuits,antenna array radiation,and wave scattering.In the evolution of this technology,DDM has gradually manifested its remarkable power of tackling complex EM problems through its merging with Laplace,wave,Maxwell equations,as well as surface integral equations and volume integral equations.The further evolved advanced algorithms such as overlapped DDM and non-overlapped DDM are also reviewed.The efficiency of the DDMs depends strongly on the TCs of EM fields at the interface among adjacent sub-domains.The diversity of TCs in differential and integral equations generates a variety of DDMs.Due to the independence of sub-domains,the DDMs are inherently well-suited for parallel processing with high flexibility,making them particularly effective for EM full-wave simulations on distributed computers.Finally,a list of remaining challenging technical issues and future perspective on the fast-evolving field will be provided.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA 0716601)the National Natural Science Foundation of China(Grant No.U22B2016).
文摘Antennas are essential components of any wireless system due to their irreplaceable functions in transmitting and receiving electromagnetic waves.Antenna radiation is based on the free electron resonance,leading to a concrete relation between its physical size and operating frequency.This fundamental principle makes it unrealizable to design well-radiated antennas with extremely small dimensions,e.g.,milli-wavelength scales.Here,to overturn this commonsense correlation,an extremely miniaturization methodology of antennas is developed by integrating an arbitrary-sized antenna with an ohmic-biased transistor(OBT)circuit.In this way,we thousandfold miniaturize the antenna to an overall size at milli-wavelength scales,including the OBT circuits.Proven by the experiments in the demonstration systems,the wireless system with this thousandfold miniaturized antenna receives electromagnetic waves well.This methodology would be widely utilized in space-limited wireless systems that cannot provide enough space for antennas,benefiting various exciting areas,such as information technologies,photoelectricity physics,biomedical science,and so on.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375002 and 62101010)We sincerely thank Beijing Sanse Magnetic Exploration Technology Co.,Ltd.for providing the measurement equipment for the experiment.We also extend our gratitude to Wei Xiao for their valuable writing suggestions.
文摘Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological exploration,featuring both hardware module integration and data processing methods.The hardware module incorporates a multi-rotor drone,a cesium optically pumped magnetometer,and a synchronized data acquisition system for processing magnetic and GPS position data.It can rapidly measure the magnetic field of the archaeological sites to capture the magnetic anomaly signals.The data processing methods consist of diurnal variation correction,survey line correction,aeromagnetic noise suppression,and a leveling algorithm based on curvelet transform,which is capable of identifying magnetic anomaly signals within the measured magnetic field.Field tests were conducted at the Song Dynasty iron smelting site in Xiacaopu,Anxi County,Fujian Province,China,where the system successfully discovered a new smelting furnace relic,which was subsequently confirmed through excavation.
基金supported by the National Natural Science Foundation of China(Grant Nos.62293495 and 62201021)the Young Elite Scientists Sponsorship Program(Grant No.2023QNRC001).
文摘Integrated photonic gyroscopes(IPGs)have emerged as a promising alternative to other gyroscopes,providing high sensitivity,compactness,and low power consumption,especially being more conducive to integration.In this review,we discuss recent advances in IPG technology and research,including the different types of IPGs currently being developed,such as waveguide spiral-based,ring laser gyroscope,and passive ring resonator based IPGs.We highlight the efforts dedicated to improve the stability,accuracy,and resolution of IPGs,such as using narrow-band laser diodes and using a high-stability,low-noise power supply system.Additionally,we provide an overview of the key performance measures of IPGs,including resolution,drifting,stability,noise cancellation as well as their interrelationships.Finally,we discuss challenges and future directions for the IPG research,including improving long-term stability and addressing sensitivity to shock and vibrations.
基金supported by the National Research Foundation,Singapore,and Infocomm Media Development Authority under its Future Communications Research&Development Programme(Grant No.FCP-NTU-RG-2024-025)the Imperial-NTU Collaboration Fund(Grant No.INCF-2025-005)+1 种基金the National Natural Science Foundation of China(Grant Nos.62301018 and 62271376)the Guangdong Natural Science Fund for Distinguished Young Scholar(Grant No.2023B1515020079).
文摘The rapid proliferation of Internet of things(IoT)devices has driven an unprecedented demand for efficient multi-user communication solutions.Traditional methods for multiplexing,such as frequency-division and code-division multiplexing,are struggling to accommodate the increasing number of users and the limited spectrum resources available.To address these chal-lenges,this paper presents an innovative wireless communication system that leverages reconfigurable intelligent surface(RIS)and orbital angular momentum(OAM)technologies to enhance spectral efficiency,reduce interference,and meet the high data rate re-quirements of modern IoT applications.The proposed system integrates a multi-mode OAM transmitter to generate signals carrying multiplexed data streams,which are subsequently directed to a metasurface-based RIS.The RIS is designed to receive the incident OAM beams,demultiplex the data,and focus it in real-time to distinct spatial regions,achieving a high signal-to-noise ratio(SNR)and minimizing interference for efficient multi-user transmission.A practical 2-bit transmissive RIS design is employed,which en-ables dynamic control over OAM modes,focusing energy at different user locations in the near-field,thereby realizing flexible and independent control of each unit.To generate the multi-mode OAM beams,a simplified microstrip antenna working at 10 GHz is utilized,incorporating a multi-layer printed circuit board(PCB)isolation design to minimize coupling interference between modes,ensuring reliable and efficient mode generation.To validate the effectiveness of the proposed system,we conduct full-wave simula-tion experiments,and build a complete communication testing environment,covering the entire communication process from the multi-mode OAM transmitter to the RIS-based communication link.Experimental results demonstrate that the proposed solution can effectively achieve near-field spot-beam focusing through the RIS and enable multi-user,same-frequency data separation at each fo-cal point.This provides a novel and efficient solution for high-spectral-efficiency,low-interference multi-user data interaction in IoT networks,offering new insights for enhancing multi-user access and data transmission efficiency in various IoT scenarios,including smart factories,logistics centers,and in-vehicle communications.
文摘The design of nonuniform transmission line impedance transformers is demonstrated by applying a convex optimization method.A constrained convex semidefinite relaxation problem is defined by minimizing the input reflection coefficient magnitude squared at a number of frequency values.Additional constraints on the minimum and maximum transmission line impedance values along the length of the line are imposed.The optimization process is demonstrated for real and complex loads.Such impedance transformers find broad applications in broadband impedance matching and balun design for antenna and amplifier circuits or rectifier circuits,for example in energy harvesting and wireless power transmission applications.
基金supported by the National Natural Science Foundation of China(Grant No.62101133)the Shanghai Rising Star Program(Grant No.22QC1400100).
文摘As foldable smartphones typically operate in two primary states—unfolded state and folded state,the structural changes between the two states,which can significantly impact antenna performance,such as frequency shifts and efficiency reduction,are critical for practical applications.This paper proposes to use a quarter-wavelength parasitic branch to mitigate the effect of the structural changes between the two states.With the quarter-wavelength parasitic branch,a high-efficiency deca-band mobile antenna with similar performance in both the unfolded and folded states is achieved.Prototype testing shows negligible frequency shifts(approximately 0 MHz)in the low band(LB)of 0.704–0.960 GHz,middle high band(MHB)of 1.71–2.69 GHz,and new radio(NR)bands of 3.3–3.8 GHz and 4.7–5.0 GHz between the unfolded and folded states.The efficiency reductions are 0.45 dB(from−4.98 dB to−5.43 dB)in the LB band,0.28 dB(from−2.70 dB to−2.98 dB)in the MHB band,and 0.81 dB(from−2.34 dB to−3.15 dB)in the NR band.The proposed antenna,which demonstrates minimal frequency shifts and slight efficiency degradation in the unfolded and folded states,makes it highly promising for practical applications.
文摘The future of wireless systems is anticipated to revolutionize human connectivity through a diverse range of applications.The integration of multiple wireless functionalities into a unified system presents a critical challenge due to conflicting requirements in transceiver architecture and signal processing.Recent investigations are directing attention towards the development of systems that serve dual functions,like simultaneous wireless information and power transfer and radar-communication,aimed at boosting operational efficiency and ensuring seamless communication among different wireless capabilities.This review paper aims to discuss the architectural aspects of the integration of radar sensing,data communication,and power transfer.Firstly,the integration of radar sensing and data communication is studied for both cooperating and non-cooperating radar systems with conventional and interferometric architectures.Secondly,the power harvesting approach and internal energy recycling are discussed for the fusion of data communication and energy harvesting.Thirdly,radar sensing and power transfer integration is considered with special focus on harmonic backscattering and self-powered radars.Lastly,a roadmap for next-generation multifunction systems is outlined by considering several scenarios of multiplexing and architectures.
基金supported by the National Natural Science Foundation of China(Grant No.W2433153)the National Natural Science Foundation of China under the State Major Research Instrument Program(Grant No.62027805)the Chaoyong Program(Grant No.130000-171207723/042),and the Startup Funds of Zhejiang University.
文摘Massive multiple-input multiple-output(MIMO)and intelligent reflecting surface(IRS)technologies have become a research focus for non-stationary vehicle-to-vehicle(V2V)wireless communications due to their capability to control radio propagation environment.In this paper,a non-stationary irregular geometry-based stochastic model(I-GBSM)for V2V massive MIMO systems using three-dimensional uniform linear arrays and discrete IRS at millimetre-wave operating frequencies is proposed.A new approach for determining IRS elements phase-shift using the Doppler effect and channel impulse response is introduced to mitigate channel non-stationarity and enhance propagation conditions.Unlike traditional models,it takes into account practical spherical wavefronts instead of plane wavefronts.The proposed model categorizes clusters into moving and static clusters to examine traffic density and its effects on channel characteristics in V2V environments.It employs a novel birth-death process to ensure consistency in cluster evolution.The non-stationary stochastic channel characteristics are comprehensively analyzed through simulations.These characteristics include space-time-frequency correlation functions,Doppler power spectral density,path loss,delay spread,root mean square error of the correlation function,and achievable rate across different operating frequencies.The analysis demonstrates notable performance improvements.The proposed I-GBSM is also validated by a good agreement with the results from existing models and measurements under reduced scenarios.
基金supported by the National Natural Science Foundation of China(Grant No.62476285)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant No.GZC20252693).
文摘The rapid and accurate identification of biological tissue types in resected specimens is critical to ensure complete tumor excision during surgery.By leveraging inherent electromagnetic property variations among tissues,this study presents a novel dual-port electromagnetic method that employs two-port S-parameters for quantitative tissue discrimination.The proposed technology leverages differences in the broadband electromagnetic properties among biological tissues,which are manifested as distinct attenu-ation characteristics during signal transmission.This approach allows for the successful differentiation of various tissue types,such as skin,muscle,fat,and tumor tissues,in ex vivo tumor-bearing mouse models.Specifically designed for biological tissue detection,this dual-port framework is the first to achieve a calibration-free operation and facilitate the detection of tumors with a size as small as 0.1 mm.Experimental validation in tumor-bearing mouse models demonstrated robust differentiation among skin,fat,muscle,and tumor tissues.Consistent measurements across multiple orientations were achieved,with a specific absorption rate below 0.0091 W/kg confirming operational safety.The transmission characteristics reveal significant bioelectromagnetic interactions,providing physical insights into tissue dielectric properties.This method provides a promising platform for clinical diagnostics and precision surgical guidance.
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.
文摘For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equations for a mechano-driven media system(MEs-f-MDMS).Here,by defining the effective electric and magnetic fields,the MEs-f-MDMS reduces to the stand-ard form of the Maxwell’s equations(MEs)in some engineering scenarios.This means that the accelerated motion of a medium is a source for generating electromagnetic wave,while the propagation of the waves in the system follows the classical MEs.Therefore,the standard methods for solving the MEs can be adequately applied.We first present the theoretical derivation,then we will present the solutions of the MEs-f-MDMS in both time-and frequency-space.Second,the shortcomings in classical approach regarding to the calculation of electromagnetic radiation from a rotating medium is analyzed.Third,the theory about the impact of medium rota-tion on reflection and transmission of a plane wave at an interface is considered.Fourth,the theory for quantifying the output of tri-boelectric nanogenerator is given.Fifth,since the effective fields warrant the covariance of the MEs,the Lorentz transformation can be introduced for extrapolating the effective field theory to a case there is a translation motion of the system with considering rela-tivistic effect.Finally,recent progresses about the experimental proofs in supporting the MEs-f-MDMS are covered.
基金supported by the National Natural Science Foundation of China(Grant Nos.62388102 and 61925106).
文摘In this article,we propose a novel super-resolution method for ultrawideband radar imaging,to address the problem of degraded range estimation accuracy of off-grid targets.We propose generalized atomic norm minimization(ANM)with modality demixing,dubbed ANM-MD,which effectively harnesses the sparsity of radar targets over a continuous range space.First,we demix the radar echo of targets according to their frequency dependency modalities(FDMs)in the geometrical theory of diffraction model.By modality demixing,we can suppress the influence of multiple FDMs on consequent estimation of target ranges.Then,we estimate the scattering parameters of radar targets separately in each FDM,leading to accurate estimation of target ranges.Experimental results show that our method can improve the accuracy of range estimation of off-grid targets by more than 15%compared with existing methods,leading to improved quality of super-resolution imaging.
基金supported by the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.24hytd010).
文摘Recent years have seen increased interest in optoelectronic semiconductor materials,particularly those from groups Ⅱ-Ⅵ,Ⅳ-Ⅵ,and perovskite,due to their outstanding electronic and optical properties.However,the toxicity and environmental concerns related to heavy metals like lead and cadmium have hindered their widespread commercial use,shifting the focus to AgBiS_(2),a nontoxic,cost-effective,and promising alternative.Despite significant progress,the efficiency of AgBiS_(2)remains lower than that of perovskite or cadmium-lead-based devices,primarily due to challenges in nanocrystals(NCs)synthesis and limitations in device structure and stability when using AgBiS_(2)thin films.This review evaluates these challenges by examining the synthesis process,addressing device-related limitations,and discussing recent advancements in AgBiS_(2)research and its potential applications.It includes an analysis of AgBiS_(2)’s chemical and crystal structures,as well as its optoelectronic properties.Additionally,we review improvements in synthesizing high-quality AgBiS_(2)NCs and discuss applications such as photodetectors and X-ray/photoelectrochemical sensors.Finally,we highlight the challenges and future prospects for AgBiS_(2),offering insights into its potential for various applications.
基金supported by the National Natural Science Foundation of China(Grant No.62101333)the 2024 Anhui Province University Science and Engineering Teachers’Internship Program in Enterprises(Grant No.2024jsq ygz02).
文摘In this article,the ultra-efficient transfer matrix method(U-TMM)is developed to detecting the propagation coeffi-cients of ultra-multilayered anisotropic media(UMAM)in the terahertz region.Starting from the curl Maxwell’s equations and combined with the constitutive relation,the governing equation can be described in matrix form from which the four eigenvalues are derived,so that each component of the electromagnetic field can be uniquely represented by the fixed formula.The core thought with U-TMM is to maintain tangential continuity of electromagnetic fields between different media,thereby constructing transfer matrix between various regions and achieving the calculation of propagation coefficients in UMAM.After successfully validating U-TMM through two numerical examples,we find that U-TMM compensates for the shortcomings of COMSOL software in dealing with the UMAM problems,and in addition,the computational efficiency is significantly improved compared to the conventional transfer matrix method.Finally,to verify the energy change process in UMAM,we generate color images of the propagation coeffi-cients by U-TMM in transverse electric/transverse magnetic mode,which can be applied to the analysis for materials and devices in the terahertz region.
基金supported by the National Natural Science Foundation of China(Grant Nos.62231007 and 62031010).
文摘With the increasing maturity of various computational electromagnetics algorithms,the field has evolved from traditional standalone electromagnetic simulations to a stage in which trustworthy electromagnetic computation methods serve as the core,aimed at meeting the advanced demands of computer-aided engineering.Trustworthy electromagnetic computation consists of three key aspects:trustworthy model,trustworthy mesh,and trustworthy algorithm.This paper focuses on the aspect of trustworthy mesh,aiming to establish a systematic framework and methodology for achieving trustworthy computation under the assumption that the target geometry and associated parameters are determined.The framework starts with high-fidelity geometric meshing.An effective strategy is nonconformal domain decomposition,which facilitates accurate modeling of complex geometries and diverse materials.Subsequently,efficient preconditioning methods are utilized to ensure stable convergence when solving the resulting multiscale systems associated with high-fidelity meshes.After obtaining the numerical solution,verification procedures are applied to evaluate whether the desired accuracy has been achieved.If the solution fails to meet the specified precision,adaptive mesh refinement techniques are used to automatically redistribute mesh density.The objective is to attain greater accuracy with a minimal increase in degrees of freedom,thereby enhancing computational efficiency.The adaptive refinement process proceeds iteratively until the computed solution satisfies the established accuracy criteria.Within this framework,we propose a novel,fast,physics-based self-reference method,which leverages power conservation laws to assess the accuracy of the solution.
基金supported by the National Research Council Canada(Grant Nos.HTSN-206 and HTSN-245)by the Natural Sciences and Engineering Research Council of Canada.
文摘Microwave photonics(MWP)represents a significant optical signal processing system,standing at the confluence of microwave engineering and photonics.It presents a promising way for meeting the growing demands of contemporary communication systems,radar,sensing,and signal processing.Driving the rapid advancement of MWP are pivotal technologies such as optical frequency combs,photonic integrated circuits,and advanced modulation formats.The integration of photonic integrated circuit technology with hybrid integration techniques holds the promise of realizing MWP systems on a single chip,while comb shaping technology endows MWP systems with programmable and reconfigurable capabilities.In this paper,we present a review of our recent research,which focused on exploring the full spectrum of potential applications for quantum dash lasers in MWP systems.Leveraging principles of finite impulse response filters,our MWP system not only facilitates conventional filtering but also enables instantaneous frequency measurement and waveform generation.A distinguishing feature of MWP filters is their uniform delay.After converting it into a uniform phase difference,it underpins the development of MWP-based phase antenna array systems.Furthermore,this uniform delay finds application in time-interleaved photonic analog-to-digital conversion.
