Antennae are significant chemosensory and mechanosensory organs for insects and need careful maintenance.Bees use a pair of comb-like tools located on the forelimbs to brush and remove contaminants from their antennae...Antennae are significant chemosensory and mechanosensory organs for insects and need careful maintenance.Bees use a pair of comb-like tools located on the forelimbs to brush and remove contaminants from their antennae.We filmed antenna grooming in three different bee species and observed that all bees raise their heads while grooming their antennae.We conducted a study to examine the effects of the distinctive grooming apparatus,as well as the antenna’s material and structural characteristics,on grooming behavior in both free-head and constrained-head scenarios.Head-raising increases the grooming speed by 300%compared to the situation where the head is constrained.It allows the bees to scrape the antennae 5 times per second.In addition,we proposed a mechanical model based on the morphological data to determine that raising the head increases the contact force by 50%.These findings will facilitate the development of innovative approaches for cleaning extended structures featuring bristly surfaces.展开更多
The morphology of antennae of Aphidoletes aphidimyza was observed with a scanning electron microscope. The results showed that both male and female were fourteen segmented, the male was approximately 2000 μm and the ...The morphology of antennae of Aphidoletes aphidimyza was observed with a scanning electron microscope. The results showed that both male and female were fourteen segmented, the male was approximately 2000 μm and the female was 1050μm. Six types of sensillae on the antenna were observed, viz. chaetica （Ch）, trichoidea （Tr）, basiconica （Ba）, cavity （Ca）, styloid （St） and circumfila （Ci） on the antennae of A. aphidimyza. Sensillae Ch had a long external-process, with a base surrounded by membranous sockets and a length of about 67.5 μm. Sensillae Tr were distally curved and inserted into a depression, 61.0μm long. Sensillae Ba were peg-like and 4.7μm long on the antennae. Sensillae Ca were pit-like in appearance and the diameter of the pit was 1.2μm. Sensilla St was found on the second sub-segment flagellum of the male antennae. The length of the sensilla was about 21 μm and the diameter was 1.5μm. The circurnfila, which are a unique type of sensilla found only on cecidomyiid antennae, formed loops around each of the antennal sub-segments, and were attached to the surface by a series of stalks. Sensilla St was only present on male antenna. The number of Ba and Tr was almost the same in both sexes. There were more Sensilla Ca on the male antenna than on the female, while there was more Ch on the female.展开更多
In this paper,we propose enhancements to Beetle Antennae search(BAS)algorithm,called BAS-ADAIVL to smoothen the convergence behavior and avoid trapping in localminima for a highly noin-convex objective function.We ach...In this paper,we propose enhancements to Beetle Antennae search(BAS)algorithm,called BAS-ADAIVL to smoothen the convergence behavior and avoid trapping in localminima for a highly noin-convex objective function.We achieve this by adaptively adjusting the step-size in each iteration using the adaptive moment estimation(ADAM)update rule.The proposed algorithm also increases the convergence rate in a narrow valley.A key feature of the ADAM update rule is the ability to adjust the step-size for each dimension separately instead of using the same step-size.Since ADAM is traditionally used with gradient-based optimization algorithms,therefore we first propose a gradient estimation model without the need to differentiate the objective function.Resultantly,it demonstrates excellent performance and fast convergence rate in searching for the optimum of noin-convex functions.The efficiency of the proposed algorithm was tested on three different benchmark problems,including the training of a high-dimensional neural network.The performance is compared with particle swarm optimizer(PSO)and the original BAS algorithm.展开更多
Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient...Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient R,we obtain the Bianchi identity on prism lattice.By defining an inner product of discrete differential forms,we derivethe source equation and continuity equation.Those equations compose the discrete Maxwell equations in vacuum caseon discrete manifold,which are implemented on Java development platform to simulate the Gaussian pulse radiation onantennaes.展开更多
Since the voltage source converter based high voltage direct current(VSC-HVDC)systems owns the features of nonlinearity,strong coupling and multivariable,the classical proportional integral(PI)control is hard to obtai...Since the voltage source converter based high voltage direct current(VSC-HVDC)systems owns the features of nonlinearity,strong coupling and multivariable,the classical proportional integral(PI)control is hard to obtain content control effect.Hence,a new perturbation observer based fractional-order PID(PoFoPID)control strategy is designed in this paper for(VSC-HVDC)systems with offshore wind integration,which can efficiently boost the robustness and control performance of entire system.Particularly,it employs a fractional-order PID(FoPID)fra-mework for the sake of compensating the perturbation estimate,which dramatically boost the dynamical responds of the closed-loop system,and the cooperative beetle antennae search(CBAS)algorithm is adopted to quickly and effi-ciently search its best control parameters.Besides,CBAS algorithm is able to efficiently escape a local optimum because of a suitable trade-off between global exploration and local exploitation can be realized.At last,comprehensive case studies are carried out,namely,active and reactive power tracking,5-cycle line-line-line-ground(LLLG)fault,and offshore wind farm integration.Simulation results validate superiorities and effectiveness of PoFoPID control in com-parison of that of PID control and feedback linearization sliding-mode control(FLSMC),respectively.展开更多
Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was ...Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was observed by using a scanning electron microscope. The larval antennae possess six sensilla basiconica, two sensilla chaetica and one sensillum styloconicum. Larval mouthparts possess six types of sensilla： sensilla chaetica, sensilla digitiformia, sensilla epipharyngeal, sensilla basiconica, sensilla styloconica and sensilla placodea. In the adult, seven types of sensilla are found on the antennae in males and six types of sensilla （sensilla basiconica absent） occur in females. Sexual dimorphism is also found in the number and size of these sensilla on the antennae of adults. We describe for the first time the five types of sensilla on the mouthparts of the adult of P. xylostella. This study provides useful information for further research into the function of these sensilla, and better understanding the behavioral mechanisms involved in pest control.展开更多
Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization...Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.展开更多
This paper focuses on the trajectory tracking of quadrotors under bounded external disturbances.An optimised robust controller is proposed to drive the position and attitude ofa quadrotor converge to their references ...This paper focuses on the trajectory tracking of quadrotors under bounded external disturbances.An optimised robust controller is proposed to drive the position and attitude ofa quadrotor converge to their references quickly. At first, nonsingular fast terminal slidingmode control is developed, which can guarantee not only the stability but also finite-timeconvergence of the closed-loop system. As the parameters of the designed controllers playa vital role for control performance, an improved beetle antennae search algorithm is proposedto optimise them. By employing the historical information of the beetle’s antennaeand dynamically updating the step size as well as the range of its searching, the optimisingis accelerated considerably to ensure the efficiency of the quadrotor control. The superiorityof the proposed control scheme is demonstrated by simulation experiments, from whichone can see that both the error and the overshooting of the trajectory tracking are reducedeffectively.展开更多
In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved cerami...In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved ceramic substrate,and laser sintering and microdroplet spraying processes are used to add the conductive metal on the curved substrate.The problems of gain loss,bandwidth reduction,and frequency shift caused by high temperatures are addressed by using a proper antenna design,with parasitic patches,slots,and metal resonant cavities.The antenna prototype is characterized by the curved substrates and the conductive metals for the power dividers,the patch,and the ground plane;its performance is examined up to a temperature of 600℃in a muffle furnace and compared with the results from the numerical analysis.The results show that the antenna can effectively function at 600℃and even higher temperatures.展开更多
Scanning electron microscopy was done to describe the morphology of antennaof adult male and fe- male ladybeetle, Coccinella septempunctata . Eleven-segmented, scaly antennawas 950μm in male and 980 μm in female. El...Scanning electron microscopy was done to describe the morphology of antennaof adult male and fe- male ladybeetle, Coccinella septempunctata . Eleven-segmented, scaly antennawas 950μm in male and 980 μm in female. Electron micrographs reveal the occurrence of eight typesof sensillae, viz. chaetica ( Ch) , trichoidea (Tr) , basiconica (Ba) , campaniformia (Ca) ,ampucellaceous (Am) , scolopalia (Sc) , placoidea (PI) and hook shaped sensilla on the antennae ofmale and female ladybeetles. Ch had long external-process, with base surrounded by membranous socketand the length was 60 and 70 μm in male and female ladybeetle, respectively. Sensillae Tr weredistally curved and inserted into depression, 9.0 and 15 μm long in male and female ladybeetle,respectively. Sensillae Ba were cuticular peg-like and 0.57 and 0.70 μm long on the male and femaleantennae. Sensillae Ca were small dome-like and had diameter of 3.0μm in both the sexes. SensillaeAm were pit-like in appearance and the diameter of the pit was 1.2 and 1.5 in male and femaleladybeetle, respectively. Sensillae PI were elliptical sunken plates like in both the sexes.Sensillae Sc were broad at their apex and pointed at their tip, 2.5μm. A single hook-shapedsensilla of 21.0 μm in length was present on male antenna only. Ch, Ca, Am, and PI were almostsimilar in numbers in both the sexes. Sensillae Tr were more numerous on the male antenna and Bawere more numerous on the female antenna.展开更多
This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground commu...This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground communication.The array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low SLL.First,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source antenna.Then,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating beam.Particular consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation performance.Experiment indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer configuration.The concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.展开更多
The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled p...The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled phased array antenna system is a necessary trend for the future development of the phased array,and it is also a major focus and difficulty in the current research of integrated microwave photonics.This paper firstly introduces the basic principle and development history of optical true time delay phased array antenna system based on microwave photonics,and briefly introduces the main implementation methods and integration platform of optical true time delay.Then,the application and development prospect of optical true time delay technology in beam control of phased array antenna system are mainly presented.Finally,according to the current research progress,the possible research directions of integrated optically controlled phased array antenna systems in the future are proposed.展开更多
Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for co...Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for complex impedance in automotive radar frequency range is proposed.Unlike the gradient transmission line,the wavy structure is composed of periodically semi-circular segments.By adjusting the radius of the semi-circular,the surface current is varied and concentrated on the semi-circular segments,allowing a wider tunability range of the resonant frequency.The results reveal that the bandwidth of the loaded wavy transmission line antenna improves to 9.37 GHz,which is 5.81 GHz wider than that of the loaded gradient line.The gain and the half power beam width of the loaded antenna are about 14.69 dB and 9.58°,respectively.The proposed non-uniform microstrip line scheme may open up a route for realizing wideband millimeter-wave automotive radar applications.展开更多
Considering the environmental sustainability,the ceramic substrate is preferred in conventional global navigation satellite system(GNSS)antennas.However,the high-density ceramic increases the antennas'mass,and ban...Considering the environmental sustainability,the ceramic substrate is preferred in conventional global navigation satellite system(GNSS)antennas.However,the high-density ceramic increases the antennas'mass,and bandwidth of the GNSS antenna is narrowed by the high permittivity of ceramic.To solve these issues,a compact,lightweight circularly polarized(CP),transmitting(Tx)and receiving(Rx)integrated antenna was proposed for the lightweight and wide-bandwidth GNSS communications antennas.A hollowing sandwich layer was used to balance the bandwidth and weight performance.By optimizing hollowed dimensions,a lightweight and wide bandwidth GNSS antenna could be achieved.Both Tx-Rx antennas were integrated into a printed circuit board(PCB),minimizing the satellite installation space.Simulations and measurements are conducted.The results show that the operating frequency band around 1.6 GHz(Tx)and around 1.5 GHz(Rx),with realized gains 3 dBi(Tx)and 2.5 dBi(Rx).The total mass of the proposed antenna is around 59 g within a compact space of 50 mm×50 mm×10 mm.The proposed CP GNSS antennas show excellent performance in size,mass,and bandwidth,which can be a potential solution for the micro-nano satellite-ground communications.展开更多
A triple-band miniaturized end-fire antenna based on the odd modes of spoof surface plasmonic polariton(SSPP)waveguide resonator is proposed in this paper.To meet the ever increasing demand for more communication chan...A triple-band miniaturized end-fire antenna based on the odd modes of spoof surface plasmonic polariton(SSPP)waveguide resonator is proposed in this paper.To meet the ever increasing demand for more communication channels and less antenna sizes,multi-band antennas are currently under intensive investigation.By a novel feeding method,three odd modes are excited on an SSPP waveguide resonator,which performs as an end-fire antenna operating at three bands,7.15-7.26 GHz,11.6-12.2 GHz and 13.5-13.64 GHz.It exhibits reasonably high and stable maximum gains of 5.26 dBi,7.97 dBi and 10.1 dBi and maximum efficiencies of 64%,92%and 98%at the three bands,respectively.Moreover,in the second band,the main beam angle shows a frequency dependence with a total scanning angle of 19°.The miniaturized triple-band antenna has a great potential in wireless communication systems,satellite communication and radar systems.展开更多
This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens...This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens,and innovative integrated antennas—in the context of railway 5G-R base station specifications.The advantages and disadvantages of these antenna types are compared and analyzed,and recommendations for the selection of 5G-R base station antennas are provided.Based on the special application scenarios of railway 5G-R base stations,this paper proposes connection methods between antennas and RRUs,and conducts a comparative analysis of antenna interface types.Furthermore,recommendations are provided for configuring the antenna information management module to meet the intelligent operation and maintenance requirements of the 5G-R system.The findings can serve as a reference for the selection and operation of antennas at railway 5G-R base stations.展开更多
A millimeter-wave (mmW) broadband dual circularly polarized (dual-CP) antenna with high port isolation is proposed in this paper. The dual-CP performance is realized based on the symmetrical septum circular polarizer ...A millimeter-wave (mmW) broadband dual circularly polarized (dual-CP) antenna with high port isolation is proposed in this paper. The dual-CP performance is realized based on the symmetrical septum circular polarizer based on the gap waveguide (GWG) technology. Two sets of symmetrical septum circular polarizers are used for common aperture combination,achieving the broadband dual-CP characteristics. Taking advantage of GWG structure without good electrical contact, the antenna can also be fabricated and assembled easily in the mmW band. The principle analysis of the antenna is given, and the antenna is simulated and fabricated. The measured results show that the bandwidth for S11lower than-10.7 dB and the axial ratio (AR) lower than 2.90 dB in 75-110 GHz, with realative bandwidth of 38%. Over the frequency band, the gain is higher than 9.16 dBic, and the dual-CP port isolation is greater than32 dB. The proposed antenna with dual-CP and highly isolated in a wide bandwidth range has broad application prospects in the field of mmW communication.展开更多
In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a tran...In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a transient antenna was proposed.During the research,crucial characteristics of the transient antenna formed by a shaped charge with a 30 mm diameter,such as resonant frequency,radiation pattern,and radiation efficiency,were evaluated.The typical shaped charge jet morphology was obtained based on the simulations,in which it could insight the dynamic behavior of the shaped charge jet selected.An equivalent model experiment was employed to test the radiation efficiency,and it showed that a shorting pin loading method could increase the relative bandwidth of the jet antenna to 32.8%,and the experimental results correlate with the theoretical predictions for half-wave dipole antennas reasonably well.Additionally,variations in the diameter of the shaped charge jet were found to affect the input impedance and impedance bandwidth,while the length of the jet influenced the resonant frequency of the antenna.This suggests that altering these parameters can achieve reconfigurability of the jet antenna.展开更多
Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,...Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,while the observational measurements are referenced to the satellite’s antenna phase center.The deviation between the satellite’s centroid and the antenna phase center forms the satellite antenna phase center error,which affects the precision of orbit determination.This paper takes a global navigation satellite system(GNSS)MEO satellite as an example and analyzes the actual situation of the satellite antenna phase center deviation and phase center variation based on the ground calibration data of the in-orbit satellite antenna phase center and the satellite’s in-orbit working status.The analysis shows that the antenna phase center variation caused by the satellite’s in-orbit operation is only at the centimeter level,which has a limited impact on orbit determination accuracy.The main source of precise orbit determination error is the satellite antenna phase center deviation,which can be corrected using ground calibration data.展开更多
A wideband low-profile aperture-coupled antenna based on a novel dual-mode-composite scheme is presented.The mode-composite scheme where the TM10 cavity mode and the TE121 dielec-tric resonator(DR)mode are combined of...A wideband low-profile aperture-coupled antenna based on a novel dual-mode-composite scheme is presented.The mode-composite scheme where the TM10 cavity mode and the TE121 dielec-tric resonator(DR)mode are combined offers an ap-proach to obtain a wide bandwidth accompanied by stable unidirectional radiation and high efficiency.The use of a lengthened coupling aperture that supports the one-wavelength resonance in the band of interest is an effective feed method of simultaneously excit-ing the two composite modes without compromising the increased complexity of the antenna geometry.An impedance bandwidth of 49%for|S_(11)|of less than-10 dB,a maximum gain of 10.8 dBi,and stable radiation patterns with low cross-polarization are realized ex-perimentally by a fabricated prototype.Considering the simplicity of the geometry,the wide bandwidth that can cover n77,n78,and n79 bands for the fifth generation(5G)mobile communications and the sat-isfying radiation performance,the proposed antenna would be a promising candidate for advanced wireless applications.展开更多
基金supported by the National Natural Science Foundation of China(grant No.T2422031 and No.51905556).
文摘Antennae are significant chemosensory and mechanosensory organs for insects and need careful maintenance.Bees use a pair of comb-like tools located on the forelimbs to brush and remove contaminants from their antennae.We filmed antenna grooming in three different bee species and observed that all bees raise their heads while grooming their antennae.We conducted a study to examine the effects of the distinctive grooming apparatus,as well as the antenna’s material and structural characteristics,on grooming behavior in both free-head and constrained-head scenarios.Head-raising increases the grooming speed by 300%compared to the situation where the head is constrained.It allows the bees to scrape the antennae 5 times per second.In addition,we proposed a mechanical model based on the morphological data to determine that raising the head increases the contact force by 50%.These findings will facilitate the development of innovative approaches for cleaning extended structures featuring bristly surfaces.
文摘The morphology of antennae of Aphidoletes aphidimyza was observed with a scanning electron microscope. The results showed that both male and female were fourteen segmented, the male was approximately 2000 μm and the female was 1050μm. Six types of sensillae on the antenna were observed, viz. chaetica （Ch）, trichoidea （Tr）, basiconica （Ba）, cavity （Ca）, styloid （St） and circumfila （Ci） on the antennae of A. aphidimyza. Sensillae Ch had a long external-process, with a base surrounded by membranous sockets and a length of about 67.5 μm. Sensillae Tr were distally curved and inserted into a depression, 61.0μm long. Sensillae Ba were peg-like and 4.7μm long on the antennae. Sensillae Ca were pit-like in appearance and the diameter of the pit was 1.2μm. Sensilla St was found on the second sub-segment flagellum of the male antennae. The length of the sensilla was about 21 μm and the diameter was 1.5μm. The circurnfila, which are a unique type of sensilla found only on cecidomyiid antennae, formed loops around each of the antennal sub-segments, and were attached to the surface by a series of stalks. Sensilla St was only present on male antenna. The number of Ba and Tr was almost the same in both sexes. There were more Sensilla Ca on the male antenna than on the female, while there was more Ch on the female.
文摘In this paper,we propose enhancements to Beetle Antennae search(BAS)algorithm,called BAS-ADAIVL to smoothen the convergence behavior and avoid trapping in localminima for a highly noin-convex objective function.We achieve this by adaptively adjusting the step-size in each iteration using the adaptive moment estimation(ADAM)update rule.The proposed algorithm also increases the convergence rate in a narrow valley.A key feature of the ADAM update rule is the ability to adjust the step-size for each dimension separately instead of using the same step-size.Since ADAM is traditionally used with gradient-based optimization algorithms,therefore we first propose a gradient estimation model without the need to differentiate the objective function.Resultantly,it demonstrates excellent performance and fast convergence rate in searching for the optimum of noin-convex functions.The efficiency of the proposed algorithm was tested on three different benchmark problems,including the training of a high-dimensional neural network.The performance is compared with particle swarm optimizer(PSO)and the original BAS algorithm.
基金Supported by National Key Based Research Project of China under Grant No.2004CB318000National Natural Science Foundation of China under Grant No.10871170
文摘Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient R,we obtain the Bianchi identity on prism lattice.By defining an inner product of discrete differential forms,we derivethe source equation and continuity equation.Those equations compose the discrete Maxwell equations in vacuum caseon discrete manifold,which are implemented on Java development platform to simulate the Gaussian pulse radiation onantennaes.
基金the National Natural Science Foundation of China(51807085).
文摘Since the voltage source converter based high voltage direct current(VSC-HVDC)systems owns the features of nonlinearity,strong coupling and multivariable,the classical proportional integral(PI)control is hard to obtain content control effect.Hence,a new perturbation observer based fractional-order PID(PoFoPID)control strategy is designed in this paper for(VSC-HVDC)systems with offshore wind integration,which can efficiently boost the robustness and control performance of entire system.Particularly,it employs a fractional-order PID(FoPID)fra-mework for the sake of compensating the perturbation estimate,which dramatically boost the dynamical responds of the closed-loop system,and the cooperative beetle antennae search(CBAS)algorithm is adopted to quickly and effi-ciently search its best control parameters.Besides,CBAS algorithm is able to efficiently escape a local optimum because of a suitable trade-off between global exploration and local exploitation can be realized.At last,comprehensive case studies are carried out,namely,active and reactive power tracking,5-cycle line-line-line-ground(LLLG)fault,and offshore wind farm integration.Simulation results validate superiorities and effectiveness of PoFoPID control in com-parison of that of PID control and feedback linearization sliding-mode control(FLSMC),respectively.
基金supported by the China Postdoctoral Science Foundation (2013M542388)the Postdoctoral Scientific Research Project in Shaanxi Province,China+1 种基金the Fundamental Research Funds for the Central Universities of China (2014YB087)the Agricultural Science and Technology Innovation in Shaanxi Province,China (2016NY-058)
文摘Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was observed by using a scanning electron microscope. The larval antennae possess six sensilla basiconica, two sensilla chaetica and one sensillum styloconicum. Larval mouthparts possess six types of sensilla： sensilla chaetica, sensilla digitiformia, sensilla epipharyngeal, sensilla basiconica, sensilla styloconica and sensilla placodea. In the adult, seven types of sensilla are found on the antennae in males and six types of sensilla （sensilla basiconica absent） occur in females. Sexual dimorphism is also found in the number and size of these sensilla on the antennae of adults. We describe for the first time the five types of sensilla on the mouthparts of the adult of P. xylostella. This study provides useful information for further research into the function of these sensilla, and better understanding the behavioral mechanisms involved in pest control.
文摘Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.
基金Fujian Provincial Science and Technology Major Project(No.2020HZ02014)Education and Teaching Reform Research Project for Colleges and Universities in Fujian Province(No.FBJG20210239)Huaqiao University Graduate Education Teaching Reform Research Funding Project(No.20YJG009).
文摘This paper focuses on the trajectory tracking of quadrotors under bounded external disturbances.An optimised robust controller is proposed to drive the position and attitude ofa quadrotor converge to their references quickly. At first, nonsingular fast terminal slidingmode control is developed, which can guarantee not only the stability but also finite-timeconvergence of the closed-loop system. As the parameters of the designed controllers playa vital role for control performance, an improved beetle antennae search algorithm is proposedto optimise them. By employing the historical information of the beetle’s antennaeand dynamically updating the step size as well as the range of its searching, the optimisingis accelerated considerably to ensure the efficiency of the quadrotor control. The superiorityof the proposed control scheme is demonstrated by simulation experiments, from whichone can see that both the error and the overshooting of the trajectory tracking are reducedeffectively.
基金National Natural Science Foundation of china(No.U2241205)the Natural Science Basic Research Program of Shaanxi(Nos.2022JC-33,2023-GHZD-35,and 2024JC-ZDXM-25)+1 种基金the Fundamental Research Funds for the Central Universitiesthe National 111 Project to provide fund for conducting experiments。
文摘In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved ceramic substrate,and laser sintering and microdroplet spraying processes are used to add the conductive metal on the curved substrate.The problems of gain loss,bandwidth reduction,and frequency shift caused by high temperatures are addressed by using a proper antenna design,with parasitic patches,slots,and metal resonant cavities.The antenna prototype is characterized by the curved substrates and the conductive metals for the power dividers,the patch,and the ground plane;its performance is examined up to a temperature of 600℃in a muffle furnace and compared with the results from the numerical analysis.The results show that the antenna can effectively function at 600℃and even higher temperatures.
文摘Scanning electron microscopy was done to describe the morphology of antennaof adult male and fe- male ladybeetle, Coccinella septempunctata . Eleven-segmented, scaly antennawas 950μm in male and 980 μm in female. Electron micrographs reveal the occurrence of eight typesof sensillae, viz. chaetica ( Ch) , trichoidea (Tr) , basiconica (Ba) , campaniformia (Ca) ,ampucellaceous (Am) , scolopalia (Sc) , placoidea (PI) and hook shaped sensilla on the antennae ofmale and female ladybeetles. Ch had long external-process, with base surrounded by membranous socketand the length was 60 and 70 μm in male and female ladybeetle, respectively. Sensillae Tr weredistally curved and inserted into depression, 9.0 and 15 μm long in male and female ladybeetle,respectively. Sensillae Ba were cuticular peg-like and 0.57 and 0.70 μm long on the male and femaleantennae. Sensillae Ca were small dome-like and had diameter of 3.0μm in both the sexes. SensillaeAm were pit-like in appearance and the diameter of the pit was 1.2 and 1.5 in male and femaleladybeetle, respectively. Sensillae PI were elliptical sunken plates like in both the sexes.Sensillae Sc were broad at their apex and pointed at their tip, 2.5μm. A single hook-shapedsensilla of 21.0 μm in length was present on male antenna only. Ch, Ca, Am, and PI were almostsimilar in numbers in both the sexes. Sensillae Tr were more numerous on the male antenna and Bawere more numerous on the female antenna.
基金supported by the National Natural Science Foundation of China(No.62371080 and 62031006)the National Science Foundation of Chongqing,China(No.CSTB2022NSCQ-MSX0597)the Venture&Innovation Support Program for Chongqing Overseas Returnees,China(No.cx2022063)。
文摘This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground communication.The array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low SLL.First,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source antenna.Then,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating beam.Particular consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation performance.Experiment indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer configuration.The concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.
基金supported by Fund of State Key Laboratory of IPOC(BUPT)(No.IPOC2021ZT16),China.
文摘The integrated optical true time delay phased array antenna system has the advantages of high bandwidth,small size,low loss and strong antiinterference capability,etc.The high integration of the optically controlled phased array antenna system is a necessary trend for the future development of the phased array,and it is also a major focus and difficulty in the current research of integrated microwave photonics.This paper firstly introduces the basic principle and development history of optical true time delay phased array antenna system based on microwave photonics,and briefly introduces the main implementation methods and integration platform of optical true time delay.Then,the application and development prospect of optical true time delay technology in beam control of phased array antenna system are mainly presented.Finally,according to the current research progress,the possible research directions of integrated optically controlled phased array antenna systems in the future are proposed.
基金Supported by the National Natural Science Foundation of China( 61974104)。
文摘Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for complex impedance in automotive radar frequency range is proposed.Unlike the gradient transmission line,the wavy structure is composed of periodically semi-circular segments.By adjusting the radius of the semi-circular,the surface current is varied and concentrated on the semi-circular segments,allowing a wider tunability range of the resonant frequency.The results reveal that the bandwidth of the loaded wavy transmission line antenna improves to 9.37 GHz,which is 5.81 GHz wider than that of the loaded gradient line.The gain and the half power beam width of the loaded antenna are about 14.69 dB and 9.58°,respectively.The proposed non-uniform microstrip line scheme may open up a route for realizing wideband millimeter-wave automotive radar applications.
基金funded by Basic Research Program of Jiangsu under grant BK20252030。
文摘Considering the environmental sustainability,the ceramic substrate is preferred in conventional global navigation satellite system(GNSS)antennas.However,the high-density ceramic increases the antennas'mass,and bandwidth of the GNSS antenna is narrowed by the high permittivity of ceramic.To solve these issues,a compact,lightweight circularly polarized(CP),transmitting(Tx)and receiving(Rx)integrated antenna was proposed for the lightweight and wide-bandwidth GNSS communications antennas.A hollowing sandwich layer was used to balance the bandwidth and weight performance.By optimizing hollowed dimensions,a lightweight and wide bandwidth GNSS antenna could be achieved.Both Tx-Rx antennas were integrated into a printed circuit board(PCB),minimizing the satellite installation space.Simulations and measurements are conducted.The results show that the operating frequency band around 1.6 GHz(Tx)and around 1.5 GHz(Rx),with realized gains 3 dBi(Tx)and 2.5 dBi(Rx).The total mass of the proposed antenna is around 59 g within a compact space of 50 mm×50 mm×10 mm.The proposed CP GNSS antennas show excellent performance in size,mass,and bandwidth,which can be a potential solution for the micro-nano satellite-ground communications.
基金supported in part by the Natural Science Foundation of Tianjin(No.19JCYBJC16100)the Tianjin Innovation and Entrepreneurship Training Program(No.202210060027)。
文摘A triple-band miniaturized end-fire antenna based on the odd modes of spoof surface plasmonic polariton(SSPP)waveguide resonator is proposed in this paper.To meet the ever increasing demand for more communication channels and less antenna sizes,multi-band antennas are currently under intensive investigation.By a novel feeding method,three odd modes are excited on an SSPP waveguide resonator,which performs as an end-fire antenna operating at three bands,7.15-7.26 GHz,11.6-12.2 GHz and 13.5-13.64 GHz.It exhibits reasonably high and stable maximum gains of 5.26 dBi,7.97 dBi and 10.1 dBi and maximum efficiencies of 64%,92%and 98%at the three bands,respectively.Moreover,in the second band,the main beam angle shows a frequency dependence with a total scanning angle of 19°.The miniaturized triple-band antenna has a great potential in wireless communication systems,satellite communication and radar systems.
文摘This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens,and innovative integrated antennas—in the context of railway 5G-R base station specifications.The advantages and disadvantages of these antenna types are compared and analyzed,and recommendations for the selection of 5G-R base station antennas are provided.Based on the special application scenarios of railway 5G-R base stations,this paper proposes connection methods between antennas and RRUs,and conducts a comparative analysis of antenna interface types.Furthermore,recommendations are provided for configuring the antenna information management module to meet the intelligent operation and maintenance requirements of the 5G-R system.The findings can serve as a reference for the selection and operation of antennas at railway 5G-R base stations.
文摘A millimeter-wave (mmW) broadband dual circularly polarized (dual-CP) antenna with high port isolation is proposed in this paper. The dual-CP performance is realized based on the symmetrical septum circular polarizer based on the gap waveguide (GWG) technology. Two sets of symmetrical septum circular polarizers are used for common aperture combination,achieving the broadband dual-CP characteristics. Taking advantage of GWG structure without good electrical contact, the antenna can also be fabricated and assembled easily in the mmW band. The principle analysis of the antenna is given, and the antenna is simulated and fabricated. The measured results show that the bandwidth for S11lower than-10.7 dB and the axial ratio (AR) lower than 2.90 dB in 75-110 GHz, with realative bandwidth of 38%. Over the frequency band, the gain is higher than 9.16 dBic, and the dual-CP port isolation is greater than32 dB. The proposed antenna with dual-CP and highly isolated in a wide bandwidth range has broad application prospects in the field of mmW communication.
基金supported by the"Fundamental Research Funds for the Central Universities"(Grant No.30924010801).
文摘In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a transient antenna was proposed.During the research,crucial characteristics of the transient antenna formed by a shaped charge with a 30 mm diameter,such as resonant frequency,radiation pattern,and radiation efficiency,were evaluated.The typical shaped charge jet morphology was obtained based on the simulations,in which it could insight the dynamic behavior of the shaped charge jet selected.An equivalent model experiment was employed to test the radiation efficiency,and it showed that a shorting pin loading method could increase the relative bandwidth of the jet antenna to 32.8%,and the experimental results correlate with the theoretical predictions for half-wave dipole antennas reasonably well.Additionally,variations in the diameter of the shaped charge jet were found to affect the input impedance and impedance bandwidth,while the length of the jet influenced the resonant frequency of the antenna.This suggests that altering these parameters can achieve reconfigurability of the jet antenna.
文摘Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,while the observational measurements are referenced to the satellite’s antenna phase center.The deviation between the satellite’s centroid and the antenna phase center forms the satellite antenna phase center error,which affects the precision of orbit determination.This paper takes a global navigation satellite system(GNSS)MEO satellite as an example and analyzes the actual situation of the satellite antenna phase center deviation and phase center variation based on the ground calibration data of the in-orbit satellite antenna phase center and the satellite’s in-orbit working status.The analysis shows that the antenna phase center variation caused by the satellite’s in-orbit operation is only at the centimeter level,which has a limited impact on orbit determination accuracy.The main source of precise orbit determination error is the satellite antenna phase center deviation,which can be corrected using ground calibration data.
基金supported in part by the Beijing Natural Science Foundation No.JQ22011the National Science Foundation of China for Distinguished Young Scholars under Grant No.62325102+1 种基金the National Natural Science Foundation of China under Grant No.62031004the Fundamental Research Funds for the Central Universities No.2023YJS160.
文摘A wideband low-profile aperture-coupled antenna based on a novel dual-mode-composite scheme is presented.The mode-composite scheme where the TM10 cavity mode and the TE121 dielec-tric resonator(DR)mode are combined offers an ap-proach to obtain a wide bandwidth accompanied by stable unidirectional radiation and high efficiency.The use of a lengthened coupling aperture that supports the one-wavelength resonance in the band of interest is an effective feed method of simultaneously excit-ing the two composite modes without compromising the increased complexity of the antenna geometry.An impedance bandwidth of 49%for|S_(11)|of less than-10 dB,a maximum gain of 10.8 dBi,and stable radiation patterns with low cross-polarization are realized ex-perimentally by a fabricated prototype.Considering the simplicity of the geometry,the wide bandwidth that can cover n77,n78,and n79 bands for the fifth generation(5G)mobile communications and the sat-isfying radiation performance,the proposed antenna would be a promising candidate for advanced wireless applications.
