To meet the requirements of electromagnetic(EM)theory and applied physics,this study presents an overview of the state-of-the-art research on obtaining the EM properties of media and points out potential solutions tha...To meet the requirements of electromagnetic(EM)theory and applied physics,this study presents an overview of the state-of-the-art research on obtaining the EM properties of media and points out potential solutions that can break through the bottlenecks of current methods.Firstly,based on the survey of three mainstream approaches for acquiring EM properties of media,we identify the difficulties when implementing them in realistic environments.With a focus on addressing these problems and challenges,we propose a novel paradigm for obtaining the EM properties of multi-type media in realistic environments.Particularly,within this paradigm,we describe the implementation approach of the key technology,namely“multipath extraction using heterogeneous wave propagation data in multi-spectrum cases”.Finally,the latest measurement and simulation results show that the EM properties of multi-type media in realistic environments can be precisely and efficiently acquired by the methodology proposed in this study.展开更多
In recent years, realising a ＂clean- state＂ design for the future Internet has become an important research focus. An architecture com- bining an Information-Centric Network （ICN） and Sottware-Defmed Network （SDN...In recent years, realising a ＂clean- state＂ design for the future Internet has become an important research focus. An architecture com- bining an Information-Centric Network （ICN） and Sottware-Defmed Network （SDN） （IC-SDN） has gradually attracted more attention. How- ever, the existing studies regarding IC-SDN still lack support in terms of the ＂network status awareness＂ function, resulting in unreasonable resource allocation. In this paper, we propose a new status-aware resource adaptation sche- me, i.e. a status-aware module is embedded into basic elements （Forwarding Node （FN） and Resource adaption Manager （RM））. The FNs collect the network status dynamically for the controller to reallocate network resources accor- ding to the fluctuations in environmental con- ditions. Simulation results show that, compared with the existing IC-SDN mechanism, the pro- posed scheme reduced the link bandwidth var- iance by 56% and the content delivery latency by 40%. The proof-of-concept implementation demonstrates the feasibility of our proposed sc- heme for small-scale deployment.展开更多
The dynamic parameters of multiple projectiles that are fired using multi-barrel weapons in highfrequency continuous firing modes are important indicators to measure the performance of these weapons.The characteristic...The dynamic parameters of multiple projectiles that are fired using multi-barrel weapons in highfrequency continuous firing modes are important indicators to measure the performance of these weapons.The characteristics of multiple projectiles are high randomness and large numbers launched in a short period of time,making it very difficult to obtain the real dispersion parameters of the projectiles due to the occlusion or coincidence of multiple projectiles.Using six intersecting-screen testing system,in this paper,we propose an association recognition and matching algorithm of multiple projectiles using a temporal and spatial information constraint mechanism.We extract the output signal from each detection screen and then use the wavelet transform to process the output signal.We present a method to identify and extract the time values on which the projectiles pass through the detection screens using the wavelet transform modulus maximum theory.We then use the correlation of the output signals of three parallel detection screens to establish a correlation coefficient recognition constraint function for the multiple projectiles.Based on the premise of linear projectile motion,we establish a temporal and spatial constraint matching model using the projectile’s position coordinates in each detection screen and the projectile’s time constraints within the multiple intersecting-screen geometry.We then determine the time values of the multiple projectiles in each detection screen using an iterative search cycle registration,and finally obtain the flight parameters for the multiple projectiles in the presence of uncertainty.The proposed method and algorithm were verified experimentally and can solve the problem of uncertainty in projectiles flight parameter under different multiple projectile firing states.展开更多
A model is proposed to describe the competition between two kinds of information among N random-walking individuals in an L x L square, starting from a half-and-half mixture of two kinds of information. Individuals re...A model is proposed to describe the competition between two kinds of information among N random-walking individuals in an L x L square, starting from a half-and-half mixture of two kinds of information. Individuals remain or change their information according to their neighbors＇ information. When the moving speed of individuals v is zero, the two kinds of information typically coexist, and the ratio between them increases with L and decreases with N. In the dynamic case （v 〉 0）, only one information eventually remains, and the time required for one information being left scales as Td -v^αL^β^γ.展开更多
The application of triboelectric nanogenerators(TENGs)for collecting and converting waste energy into usable electrical energy has been widely reported.However,their practical application in real-time,self-powered com...The application of triboelectric nanogenerators(TENGs)for collecting and converting waste energy into usable electrical energy has been widely reported.However,their practical application in real-time,self-powered communication systems,particularly for robust information transmission,remains underexplored.To achieve stable self-energy supply information transmission,this study presents a lightweight and flexible single-electrode TENG sensor based on a copper(Cu)foil and polytetrafluoroethylene(PTFE)composite.We systematically studied the stability of the device and found that it could maintain an output voltage of approximately 9 V after being stored at room temperature for 1 month.We also evaluated its power generation capacity,which was demonstrated by successfully lighting up to seven LEDs simultaneously.Additionally,we utilized its unique voltage signal to transmit Morse code and successfully sent the messages“SOS”and“HELLO”over a long distance.Furthermore,a 2×2 TENG array was fabricated and tested,confirming excellent channel independence with minimal crosstalk during simultaneous or selective activation.This work demonstrates that the Cu/PTFE TENG sensor is not only a stable energy harvester but also a viable platform for self-powered communication and distributed sensing and holds promise in applications integrating flexible electronics and the Internet of things.展开更多
Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-dope...Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.展开更多
In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium s...In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium seeding into negative-ion sources is a prerequisite to obtain the required negative hydrogen ion.The performance of ion source largely depends on the cesium conditions in the source.It is very necessary to quantitatively measure the amount of cesium in the source during the plasma on and off periods(vacuum stage).展开更多
To solve the problem of identification and measurement of two projectiles hitting the target at the same time,this paper proposes a projectile coordinate test method combining three photoelectric encoder detection scr...To solve the problem of identification and measurement of two projectiles hitting the target at the same time,this paper proposes a projectile coordinate test method combining three photoelectric encoder detection screens,and establishes a coordinate calculation model for two projectiles to reach the same detection screen at the same time.The design method of three photoelectric encoder detection screens and the position coordinate recognition algorithm of the blocked array photoelectric detector when projectile passing through the photoelectric encoder detection screen are studied.Using the screen projection method,the intersected linear equation of the projectile and the line laser with the main detection screen as the core coordinate plane is established,and the projectile coordinate data set formed by any two photoelectric encoder detection screens is constructed.The principle of minimum error of coordinate data set is used to determine the coordinates of two projectiles hitting the target at the same time.The rationality and feasibility of the proposed test method are verified by experiments and comparative tests.展开更多
An integrity monitoring framework is proposed to ensure the quality of the real-time Precise Point Positioning(PPP)correction data at the service end.The key contributions are designing quantitative metrics to charact...An integrity monitoring framework is proposed to ensure the quality of the real-time Precise Point Positioning(PPP)correction data at the service end.The key contributions are designing quantitative metrics to characterize the integrity status of the precise Orbit,Clock(OC)and Code Bias(OCB)corrections,and deriving the corresponding algorithms to detect and exclude anomalies,and to evaluate the real-time accuracy levels of the OCB.Compared to many prior works whose interests focused on analyzing and improving the averaged long-term accuracy,this work is established from integrity perspective.In particular,a two-layer fault detection and identification approach is developed to reduce the miss detection and false alert probabilities.The test statistics are constructed based on the raw observations from a network of worldwide sparsely distributed monitor stations.In addition,a realistic data-driven model is established to compute the Quality Indicators(QI)for healthy OCB products.The proposed scheme is validated respectively for multi-constellation OC and code bias,using historical correction data.The results suggest that the detection algorithms can effectively identify and alert the faults,so that the remaining correction errors approximate well to Gaussian distributions.Moreover,the computed QI are shown to be consistent with the truth error variations in real time.Most importantly,the position domain verification shows noticeable positioning accuracy and robustness improvements under both nominal and faulty conditions of the OCB correction data.展开更多
The lifetime of a wireless sensor network(WSN)is crucial for determining the maximum duration for data collection in Internet of Things applications.To extend the WSN's lifetime,we propose deploying an unmanned gr...The lifetime of a wireless sensor network(WSN)is crucial for determining the maximum duration for data collection in Internet of Things applications.To extend the WSN's lifetime,we propose deploying an unmanned ground vehicle(UGV)within the energy-hungry WSN.This allows nodes,including sensors and the UGV,to share their energy using wireless power transfer techniques.To optimize the UGV's trajectory,we have developed a tabu searchbased method for global optimality,followed by a clustering-based method suitable for real-world applications.When the UGV reaches a stopping point,it functions as a regular sensor with ample battery.Accordingly,we have designed optimal data and energy allocation algorithms for both centralized and distributed deployment.Simulation results demonstrate that the UGV and energy-sharing significantly extend the WSN's lifetime.This effect is especially prominent in sparsely connected WSNs compared to highly connected ones,and energy-sharing has a more pronounced impact on network lifetime extension than UGV mobility.展开更多
Aiming at the problem of insufficient feature extraction in single scale neural network model and the problem that convolutional neural network cannot process sequential tasks in the classification of EEG signals in d...Aiming at the problem of insufficient feature extraction in single scale neural network model and the problem that convolutional neural network cannot process sequential tasks in the classification of EEG signals in depression,a hybrid model(BFTCNet)of dualbranch convolutional neural network(Bi_CNN)and temporal convolutional network(TCN)based on feature recalibration(FR)was proposed to classify EEG signals of depressed patients and healthy controls.Firstly,Bi_CNN module was used to extract the mixed EEG features between different frequency bands and different channels.Secondly,FR module was used to enhance the features extracted by Bi_CNN.Finally,TCN with dilated causal convolution was used for the sequence learning to capture the temporal dependency between features.In this study,128 EEG channels of resting-state(closed-eye)EEG data from the public dataset MODMA were used as experimental data,including 29 healthy controls and 24 depression patients.The performance of the model was evaluated by the 10-fold cross validation method.The proposed BFTCNet achieves a classification accuracy of 95.98%,F1 score value of 95.47%,sensitivity and specificity of 94.21%and 97.50%,respectively.Compared with the single-scale network model EEGNet-8,2,the classification accuracy and F1 value are improved by 1.5%and 1.48%,respectively.Meanwhile,the ablation experiment proved that each sub-module had its contribution to the improvement of the model’s classification ability.展开更多
Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This pa...Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This paper investigates the human body RCS at 26 GHz via multiangle channel measurements under different clothing conditions.Based on calibrated electromagnetic(EM)parameters,the RCS characteristics of the human body in far-field conditions are analyzed using ray-tracing(RT)simulations.Some suggestions for the design of ISAC systems are also discussed.The results provide a solid theoretical foundation and practical reference for the modeling of target scattering characteristics for ISAC channels.展开更多
KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 e...KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 eV and p-type character.The infrared transmission spectra of single crystals yielded an optical band gap of~0.3 eV.Angle-resolved photoemission spectroscopy reveals a bulk energy gap at the Brillouin zone center,with no observable surface state,suggesting that KAg_(3)Te_(2)is a topological trivial narrow-gap semiconductor.The experimentally determined effective mass of the holes in KAg_(3)Te_(2)is very small(~0.12 me).The valence band maximum is quasi-two-dimensional,while the conduction band minimum is fully three-dimensional.Such intriguing dimensional anisotropy can be attributed to the distinct orbital contributions from K,Ag,and Te atoms to the respective bands.展开更多
Software systems play increasing important roles in modern society,and the ability against attacks is of great practical importance to crucial software systems,resulting in that the structure and robustness of softwar...Software systems play increasing important roles in modern society,and the ability against attacks is of great practical importance to crucial software systems,resulting in that the structure and robustness of software systems have attracted a tremendous amount of interest in recent years.In this paper,based on the source code of Tar and MySQL,we propose an approach to generate coupled software networks and construct three kinds of directed software networks:The function call network,the weakly coupled network and the strongly coupled network.The structural properties of these complex networks are extensively investigated.It is found that the average influence and the average dependence for all functions are the same.Moreover,eight attacking strategies and two robustness indicators(the weakly connected indicator and the strongly connected indicator)are introduced to analyze the robustness of software networks.This shows that the strongly coupled network is just a weakly connected network rather than a strongly connected one.For MySQL,high in-degree strategy outperforms other attacking strategies when the weakly connected indicator is used.On the other hand,high out-degree strategy is a good choice when the strongly connected indicator is adopted.This work will highlight a better understanding of the structure and robustness of software networks.展开更多
The first-principles calculations based on density functional theory are used to obtain structural,mechanical,and electronic properties of Zr-Te compounds.The optimized structural parameters are consistent with the av...The first-principles calculations based on density functional theory are used to obtain structural,mechanical,and electronic properties of Zr-Te compounds.The optimized structural parameters are consistent with the available experimental data.The calculated mechanical properties and formation energy show that the Zr-Te compounds are all mechanically and thermodynamically stable.The bulk modulus B,shear modulus G,Young’s modulus E,Debye temperatureΘD,and sound velocity vm are listed,which are positively correlated with the increasing of atomic fraction of Zr.The behaviors of density of states of Zr-Te compounds are obtained.Furthermore,the electronic properties are discussed to clarify the bonding characteristics of compounds.The electronic characteristics demonstrate that the Zr-Te systems with different phases are both covalent and metallic.展开更多
With the dawning of the Internet of Everything(IoE) era, more and more novel applications are being deployed. However, resource constrained devices cannot fulfill the resource-requirements of these applications. This ...With the dawning of the Internet of Everything(IoE) era, more and more novel applications are being deployed. However, resource constrained devices cannot fulfill the resource-requirements of these applications. This paper investigates the computation offloading problem of the coexistence and synergy between fog computing and cloud computing in IoE by jointly optimizing the offloading decisions, the allocation of computation resource and transmit power. Specifically, we propose an energy-efficient computation offloading and resource allocation(ECORA) scheme to minimize the system cost. The simulation results verify the proposed scheme can effectively decrease the system cost by up to 50% compared with the existing schemes, especially for the scenario that the computation resource of fog computing is relatively small or the number of devices increases.展开更多
In this paper,an Unmanned Aerial Vehicle(UAV)-assisted relay communication system is studied,where a UAV is served as a flying relay to maintain a communication link between a mobile source node and a remote destinati...In this paper,an Unmanned Aerial Vehicle(UAV)-assisted relay communication system is studied,where a UAV is served as a flying relay to maintain a communication link between a mobile source node and a remote destination node.Specifically,an average outage probability minimization problem is formulated firstly,with the constraints on the transmission power of the source node,the maximum energy consumption budget,the transmission power,the speed and acceleration of the flying UAV relay.Next,the closed-form of outage probability is derived,under the hybrid line-of-sight and non-line-of-sight probability channel model.To deal with the formulated nonconvex optimization,a long-term proactive optimization mechanism is developed.In particular,firstly,an approximation for line-of-sight probability and a reformulation of the primal problem are given,respectively.Then,the reformulated problem is transformed into two subproblems:one is the transmission power optimization with given UAV’s trajectory and the other is the trajectory optimization with given transmission power allocation.Next,two subproblems are tackled via tailoring primal–dual subgradient method and successive convex approximation,respectively.Furthermore,a proactive optimization algorithm is proposed to jointly optimize the transmission power allocation and the three-dimensional trajectory.Finally,simulation results demonstrate the performance of the proposed algorithm under various parameter configurations.展开更多
The inherent mathematic principle of active jamming against the wideband linear frequency modulated（LFM） radar is investigated. According to different generation strategies, the active jamming methods are reclassifi...The inherent mathematic principle of active jamming against the wideband linear frequency modulated（LFM） radar is investigated. According to different generation strategies, the active jamming methods are reclassified into three groups, i.e.,non-coherent jamming（NCJ）, convolution jamming（CJ） and multiplying jamming（MJ）. Based on the classification, the mathematic principles of different active jamming groups are put forward, which describe the relationships between the modulated signals and the jamming results. The advantages and disadvantages of different groups are further analyzed, which provides a new perspective for the study of jamming/anti-jamming methods and a potential for engineers to integrate similar jamming methods into one jammer platform. The analyses and simulation results of some typical active jamming methods prove the validity of the proposed mathematics principle.展开更多
According to the pulverized coal combustion flame image texture features of the rotary-kiln oxide pellets sintering process,a combustion working condition recognition method based on the generalized learning vector(GL...According to the pulverized coal combustion flame image texture features of the rotary-kiln oxide pellets sintering process,a combustion working condition recognition method based on the generalized learning vector(GLVQ) neural network is proposed.Firstly,the numerical flame image is analyzed to extract texture features,such as energy,entropy and inertia,based on grey-level co-occurrence matrix(GLCM) to provide qualitative information on the changes in the visual appearance of the flame.Then the kernel principal component analysis(KPCA) method is adopted to deduct the input vector with high dimensionality so as to reduce the GLVQ target dimension and network scale greatly.Finally,the GLVQ neural network is trained by using the normalized texture feature data.The test results show that the proposed KPCA-GLVQ classifer has an excellent performance on training speed and correct recognition rate,and it meets the requirement for real-time combustion working condition recognition for the rotary kiln process.展开更多
This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the ...This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the information of proximal（preceding and following） trains is used in the controller design. Based on available proximal information（prox-info） of location, speed, and acceleration, a direct adaptive control is designed to maintain the tracking interval at the minimum safe distance. Based on available prox-info of location, an observer-based adaptive control is designed to achieve the same target, which alleviates the requirements of equipped sensors to measure prox-info of speed and acceleration. The developed schemes are capable of on-line estimating of the unknown system parameters and stabilizing the closed-loop system, the string stability of train platoon is guaranteed on the basis of Lyapunov stability theorem. Numerical simulation results are presented to verify the effectiveness of the proposed control laws.展开更多
基金supported by the Beijing Natural Science Foundation(No.L212029)the National Natural Science Foundation of China(No.62271043).
文摘To meet the requirements of electromagnetic(EM)theory and applied physics,this study presents an overview of the state-of-the-art research on obtaining the EM properties of media and points out potential solutions that can break through the bottlenecks of current methods.Firstly,based on the survey of three mainstream approaches for acquiring EM properties of media,we identify the difficulties when implementing them in realistic environments.With a focus on addressing these problems and challenges,we propose a novel paradigm for obtaining the EM properties of multi-type media in realistic environments.Particularly,within this paradigm,we describe the implementation approach of the key technology,namely“multipath extraction using heterogeneous wave propagation data in multi-spectrum cases”.Finally,the latest measurement and simulation results show that the EM properties of multi-type media in realistic environments can be precisely and efficiently acquired by the methodology proposed in this study.
基金supported in part by the National Basic Research Program of China(973 Program)under Grant No.2013CB329100the National Natural Science Foundation of China under Grants No.61232017,No.61271200the Fundamental Research Funds for the Central Universities under Grant No.2013YJS007
文摘In recent years, realising a ＂clean- state＂ design for the future Internet has become an important research focus. An architecture com- bining an Information-Centric Network （ICN） and Sottware-Defmed Network （SDN） （IC-SDN） has gradually attracted more attention. How- ever, the existing studies regarding IC-SDN still lack support in terms of the ＂network status awareness＂ function, resulting in unreasonable resource allocation. In this paper, we propose a new status-aware resource adaptation sche- me, i.e. a status-aware module is embedded into basic elements （Forwarding Node （FN） and Resource adaption Manager （RM））. The FNs collect the network status dynamically for the controller to reallocate network resources accor- ding to the fluctuations in environmental con- ditions. Simulation results show that, compared with the existing IC-SDN mechanism, the pro- posed scheme reduced the link bandwidth var- iance by 56% and the content delivery latency by 40%. The proof-of-concept implementation demonstrates the feasibility of our proposed sc- heme for small-scale deployment.
基金been supported by Project of the National Natural Science Foundation of China(No.62073256)the Shaanxi Provincial Science and Technology Department(No.2020GY-125)Xi’an Science and Technology Innovation talent service enterprise project(No.2020KJRC0041)。
文摘The dynamic parameters of multiple projectiles that are fired using multi-barrel weapons in highfrequency continuous firing modes are important indicators to measure the performance of these weapons.The characteristics of multiple projectiles are high randomness and large numbers launched in a short period of time,making it very difficult to obtain the real dispersion parameters of the projectiles due to the occlusion or coincidence of multiple projectiles.Using six intersecting-screen testing system,in this paper,we propose an association recognition and matching algorithm of multiple projectiles using a temporal and spatial information constraint mechanism.We extract the output signal from each detection screen and then use the wavelet transform to process the output signal.We present a method to identify and extract the time values on which the projectiles pass through the detection screens using the wavelet transform modulus maximum theory.We then use the correlation of the output signals of three parallel detection screens to establish a correlation coefficient recognition constraint function for the multiple projectiles.Based on the premise of linear projectile motion,we establish a temporal and spatial constraint matching model using the projectile’s position coordinates in each detection screen and the projectile’s time constraints within the multiple intersecting-screen geometry.We then determine the time values of the multiple projectiles in each detection screen using an iterative search cycle registration,and finally obtain the flight parameters for the multiple projectiles in the presence of uncertainty.The proposed method and algorithm were verified experimentally and can solve the problem of uncertainty in projectiles flight parameter under different multiple projectile firing states.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61173183, 60973152, and 60573172)the Superior University Doctor Subject Special Scientific Research Foundation of China (Grant No. 20070141014)the Natural Science Foundation of Liaoning Province of China (Grant No. 20082165)
文摘A model is proposed to describe the competition between two kinds of information among N random-walking individuals in an L x L square, starting from a half-and-half mixture of two kinds of information. Individuals remain or change their information according to their neighbors＇ information. When the moving speed of individuals v is zero, the two kinds of information typically coexist, and the ratio between them increases with L and decreases with N. In the dynamic case （v 〉 0）, only one information eventually remains, and the time required for one information being left scales as Td -v^αL^β^γ.
基金supported by the State Key Laboratory of ASIC and System,Fudan University(Grant No.2021KF005).
文摘The application of triboelectric nanogenerators(TENGs)for collecting and converting waste energy into usable electrical energy has been widely reported.However,their practical application in real-time,self-powered communication systems,particularly for robust information transmission,remains underexplored.To achieve stable self-energy supply information transmission,this study presents a lightweight and flexible single-electrode TENG sensor based on a copper(Cu)foil and polytetrafluoroethylene(PTFE)composite.We systematically studied the stability of the device and found that it could maintain an output voltage of approximately 9 V after being stored at room temperature for 1 month.We also evaluated its power generation capacity,which was demonstrated by successfully lighting up to seven LEDs simultaneously.Additionally,we utilized its unique voltage signal to transmit Morse code and successfully sent the messages“SOS”and“HELLO”over a long distance.Furthermore,a 2×2 TENG array was fabricated and tested,confirming excellent channel independence with minimal crosstalk during simultaneous or selective activation.This work demonstrates that the Cu/PTFE TENG sensor is not only a stable energy harvester but also a viable platform for self-powered communication and distributed sensing and holds promise in applications integrating flexible electronics and the Internet of things.
基金supported by the Zhanjiang Science and Technology Plan Project(No.2022A05022)Science and Technology Development Special Project of Zhanjiang(No.2023A21616)Research Project of Guangdong Ocean University(No.060302112102).
文摘Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.
基金supported by the HFIPS Director’s Fund(Nos.YZJJQY202204 and 2021YZGH02)the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)+1 种基金the Natural Science Foundation of Anhui Province(No.2208085MA19)the National Key R&D Program of China(Nos.2017YFE300103 and 2017YFE300503)。
文摘In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium seeding into negative-ion sources is a prerequisite to obtain the required negative hydrogen ion.The performance of ion source largely depends on the cesium conditions in the source.It is very necessary to quantitatively measure the amount of cesium in the source during the plasma on and off periods(vacuum stage).
基金supported by National Natural Science Foundation of China(Grant No.62073256)Shaanxi Provincial Science and Technology Department(Grant No.2023-YBGY-342)。
文摘To solve the problem of identification and measurement of two projectiles hitting the target at the same time,this paper proposes a projectile coordinate test method combining three photoelectric encoder detection screens,and establishes a coordinate calculation model for two projectiles to reach the same detection screen at the same time.The design method of three photoelectric encoder detection screens and the position coordinate recognition algorithm of the blocked array photoelectric detector when projectile passing through the photoelectric encoder detection screen are studied.Using the screen projection method,the intersected linear equation of the projectile and the line laser with the main detection screen as the core coordinate plane is established,and the projectile coordinate data set formed by any two photoelectric encoder detection screens is constructed.The principle of minimum error of coordinate data set is used to determine the coordinates of two projectiles hitting the target at the same time.The rationality and feasibility of the proposed test method are verified by experiments and comparative tests.
基金supported by supported by the National Key Research and Development Plan,China(No.2023YFB3906501)the National Natural Science Foundation of China(No.42227802)the Fundamental Research Funds for the Central Universities,China(No.501JCGG2024133001)。
文摘An integrity monitoring framework is proposed to ensure the quality of the real-time Precise Point Positioning(PPP)correction data at the service end.The key contributions are designing quantitative metrics to characterize the integrity status of the precise Orbit,Clock(OC)and Code Bias(OCB)corrections,and deriving the corresponding algorithms to detect and exclude anomalies,and to evaluate the real-time accuracy levels of the OCB.Compared to many prior works whose interests focused on analyzing and improving the averaged long-term accuracy,this work is established from integrity perspective.In particular,a two-layer fault detection and identification approach is developed to reduce the miss detection and false alert probabilities.The test statistics are constructed based on the raw observations from a network of worldwide sparsely distributed monitor stations.In addition,a realistic data-driven model is established to compute the Quality Indicators(QI)for healthy OCB products.The proposed scheme is validated respectively for multi-constellation OC and code bias,using historical correction data.The results suggest that the detection algorithms can effectively identify and alert the faults,so that the remaining correction errors approximate well to Gaussian distributions.Moreover,the computed QI are shown to be consistent with the truth error variations in real time.Most importantly,the position domain verification shows noticeable positioning accuracy and robustness improvements under both nominal and faulty conditions of the OCB correction data.
基金supported by the National Natural Science Foundation of China(No.62171486 and No.U2001213)the Guangdong Basic and Applied Basic Research Project(2022A1515140166)。
文摘The lifetime of a wireless sensor network(WSN)is crucial for determining the maximum duration for data collection in Internet of Things applications.To extend the WSN's lifetime,we propose deploying an unmanned ground vehicle(UGV)within the energy-hungry WSN.This allows nodes,including sensors and the UGV,to share their energy using wireless power transfer techniques.To optimize the UGV's trajectory,we have developed a tabu searchbased method for global optimality,followed by a clustering-based method suitable for real-world applications.When the UGV reaches a stopping point,it functions as a regular sensor with ample battery.Accordingly,we have designed optimal data and energy allocation algorithms for both centralized and distributed deployment.Simulation results demonstrate that the UGV and energy-sharing significantly extend the WSN's lifetime.This effect is especially prominent in sparsely connected WSNs compared to highly connected ones,and energy-sharing has a more pronounced impact on network lifetime extension than UGV mobility.
基金supported by Natural Science Foundation of Gansu Province(No.21JR11RA062)University Innovation Fund of Gansu Province(No.2022A-047).
文摘Aiming at the problem of insufficient feature extraction in single scale neural network model and the problem that convolutional neural network cannot process sequential tasks in the classification of EEG signals in depression,a hybrid model(BFTCNet)of dualbranch convolutional neural network(Bi_CNN)and temporal convolutional network(TCN)based on feature recalibration(FR)was proposed to classify EEG signals of depressed patients and healthy controls.Firstly,Bi_CNN module was used to extract the mixed EEG features between different frequency bands and different channels.Secondly,FR module was used to enhance the features extracted by Bi_CNN.Finally,TCN with dilated causal convolution was used for the sequence learning to capture the temporal dependency between features.In this study,128 EEG channels of resting-state(closed-eye)EEG data from the public dataset MODMA were used as experimental data,including 29 healthy controls and 24 depression patients.The performance of the model was evaluated by the 10-fold cross validation method.The proposed BFTCNet achieves a classification accuracy of 95.98%,F1 score value of 95.47%,sensitivity and specificity of 94.21%and 97.50%,respectively.Compared with the single-scale network model EEGNet-8,2,the classification accuracy and F1 value are improved by 1.5%and 1.48%,respectively.Meanwhile,the ablation experiment proved that each sub-module had its contribution to the improvement of the model’s classification ability.
基金supported by the National Natural Science Foundation of China under Grant No.62271043Ministry of Education of China under Grant No.8091B032123Beijing Natural Science Foundation under Grant No.L212029。
文摘Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This paper investigates the human body RCS at 26 GHz via multiangle channel measurements under different clothing conditions.Based on calibrated electromagnetic(EM)parameters,the RCS characteristics of the human body in far-field conditions are analyzed using ray-tracing(RT)simulations.Some suggestions for the design of ISAC systems are also discussed.The results provide a solid theoretical foundation and practical reference for the modeling of target scattering characteristics for ISAC channels.
基金Project supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.
文摘KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 eV and p-type character.The infrared transmission spectra of single crystals yielded an optical band gap of~0.3 eV.Angle-resolved photoemission spectroscopy reveals a bulk energy gap at the Brillouin zone center,with no observable surface state,suggesting that KAg_(3)Te_(2)is a topological trivial narrow-gap semiconductor.The experimentally determined effective mass of the holes in KAg_(3)Te_(2)is very small(~0.12 me).The valence band maximum is quasi-two-dimensional,while the conduction band minimum is fully three-dimensional.Such intriguing dimensional anisotropy can be attributed to the distinct orbital contributions from K,Ag,and Te atoms to the respective bands.
基金supported by the Beijing Education Commission Science and Technology Project(No.KM201811417005)the National Natural Science Foundation of China(No.62173237)+6 种基金the Aeronautical Science Foundation of China(No.20240055054001)the Open Fund of State Key Laboratory of Satellite Navigation System and Equipment Technology(No.CEPNT2023A01)Joint Fund of Ministry of Natural Resources Key Laboratory of Spatiotemporal Perception and Intelligent Processing(No.232203)the Civil Aviation Flight Technology and Flight Safety Engineering Technology Research Center of Sichuan(No.GY2024-02B)the Applied Basic Research Programs of Liaoning Province(No.2025JH2/101300011)the General Project of Liaoning Provincial Education Department(No.20250054)Research on Safety Intelligent Management Technology and Systems for Mixed Operations of General Aviation Aircraft in Low-Altitude Airspace(No.310125011).
文摘Software systems play increasing important roles in modern society,and the ability against attacks is of great practical importance to crucial software systems,resulting in that the structure and robustness of software systems have attracted a tremendous amount of interest in recent years.In this paper,based on the source code of Tar and MySQL,we propose an approach to generate coupled software networks and construct three kinds of directed software networks:The function call network,the weakly coupled network and the strongly coupled network.The structural properties of these complex networks are extensively investigated.It is found that the average influence and the average dependence for all functions are the same.Moreover,eight attacking strategies and two robustness indicators(the weakly connected indicator and the strongly connected indicator)are introduced to analyze the robustness of software networks.This shows that the strongly coupled network is just a weakly connected network rather than a strongly connected one.For MySQL,high in-degree strategy outperforms other attacking strategies when the weakly connected indicator is used.On the other hand,high out-degree strategy is a good choice when the strongly connected indicator is adopted.This work will highlight a better understanding of the structure and robustness of software networks.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574254)the Key Research Project of Science and Technology Department of Shaanxi Province,China(Grant Nos.2018GY-044 and 2017ZDXM-GY-114)+2 种基金the Innovation Talent Promotion Project of Shaanxi Province,China(Grant No.2019KJXX-034)the Science and Technology Program of Sichuan Province,China(Grant No.2018JY0161)the Fund of the State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,China(Grant No.SKLSP201843).
文摘The first-principles calculations based on density functional theory are used to obtain structural,mechanical,and electronic properties of Zr-Te compounds.The optimized structural parameters are consistent with the available experimental data.The calculated mechanical properties and formation energy show that the Zr-Te compounds are all mechanically and thermodynamically stable.The bulk modulus B,shear modulus G,Young’s modulus E,Debye temperatureΘD,and sound velocity vm are listed,which are positively correlated with the increasing of atomic fraction of Zr.The behaviors of density of states of Zr-Te compounds are obtained.Furthermore,the electronic properties are discussed to clarify the bonding characteristics of compounds.The electronic characteristics demonstrate that the Zr-Te systems with different phases are both covalent and metallic.
基金supported by the Fundamental Research Funds for the Central Universities (No. 2018YJS008)the National Natural Science Foundation of China (61471031, 61661021, 61531009)+4 种基金Beijing Natural Science Foundation (L182018)the Open Research Fund of National Mobile Communications Research Laboratory, Southeast University (No. 2017D14)the State Key Laboratory of Rail Traffi c Control and Safety (Contract No. RCS2017K009)Science and Technology Program of Jiangxi Province (20172BCB22016, 20171BBE50057)Shenzhen Science and Technology Program under Grant (No. JCYJ20170817110410346)
文摘With the dawning of the Internet of Everything(IoE) era, more and more novel applications are being deployed. However, resource constrained devices cannot fulfill the resource-requirements of these applications. This paper investigates the computation offloading problem of the coexistence and synergy between fog computing and cloud computing in IoE by jointly optimizing the offloading decisions, the allocation of computation resource and transmit power. Specifically, we propose an energy-efficient computation offloading and resource allocation(ECORA) scheme to minimize the system cost. The simulation results verify the proposed scheme can effectively decrease the system cost by up to 50% compared with the existing schemes, especially for the scenario that the computation resource of fog computing is relatively small or the number of devices increases.
基金co-supported by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province(No.BK20190030)the National Natural Science Foundation of China(Nos.61871398 and 61931011)the National Key R&D Program of China(No.2018YFB1801103)。
文摘In this paper,an Unmanned Aerial Vehicle(UAV)-assisted relay communication system is studied,where a UAV is served as a flying relay to maintain a communication link between a mobile source node and a remote destination node.Specifically,an average outage probability minimization problem is formulated firstly,with the constraints on the transmission power of the source node,the maximum energy consumption budget,the transmission power,the speed and acceleration of the flying UAV relay.Next,the closed-form of outage probability is derived,under the hybrid line-of-sight and non-line-of-sight probability channel model.To deal with the formulated nonconvex optimization,a long-term proactive optimization mechanism is developed.In particular,firstly,an approximation for line-of-sight probability and a reformulation of the primal problem are given,respectively.Then,the reformulated problem is transformed into two subproblems:one is the transmission power optimization with given UAV’s trajectory and the other is the trajectory optimization with given transmission power allocation.Next,two subproblems are tackled via tailoring primal–dual subgradient method and successive convex approximation,respectively.Furthermore,a proactive optimization algorithm is proposed to jointly optimize the transmission power allocation and the three-dimensional trajectory.Finally,simulation results demonstrate the performance of the proposed algorithm under various parameter configurations.
基金supported by the National Natural Science Foundation of China(61271442)
文摘The inherent mathematic principle of active jamming against the wideband linear frequency modulated（LFM） radar is investigated. According to different generation strategies, the active jamming methods are reclassified into three groups, i.e.,non-coherent jamming（NCJ）, convolution jamming（CJ） and multiplying jamming（MJ）. Based on the classification, the mathematic principles of different active jamming groups are put forward, which describe the relationships between the modulated signals and the jamming results. The advantages and disadvantages of different groups are further analyzed, which provides a new perspective for the study of jamming/anti-jamming methods and a potential for engineers to integrate similar jamming methods into one jammer platform. The analyses and simulation results of some typical active jamming methods prove the validity of the proposed mathematics principle.
基金supported by China Postdoctoral Science Foundation(No.20110491510)Program for Liaoning Excellent Talents in University(No.LJQ2011027)+1 种基金Anshan Science and Technology Project(No.2011MS11)Special Research Foundation of University of Science and Technology of Liaoning(No.2011zx10)
文摘According to the pulverized coal combustion flame image texture features of the rotary-kiln oxide pellets sintering process,a combustion working condition recognition method based on the generalized learning vector(GLVQ) neural network is proposed.Firstly,the numerical flame image is analyzed to extract texture features,such as energy,entropy and inertia,based on grey-level co-occurrence matrix(GLCM) to provide qualitative information on the changes in the visual appearance of the flame.Then the kernel principal component analysis(KPCA) method is adopted to deduct the input vector with high dimensionality so as to reduce the GLVQ target dimension and network scale greatly.Finally,the GLVQ neural network is trained by using the normalized texture feature data.The test results show that the proposed KPCA-GLVQ classifer has an excellent performance on training speed and correct recognition rate,and it meets the requirement for real-time combustion working condition recognition for the rotary kiln process.
基金Project supported by the Beijing Jiaotong University Research Program,China(Grant No.RCS2014ZT18)the Fundamental Research Funds for Central Universities,China(Grant No.2015JBZ007)the National Natural Science Foundation of China(Grant Nos.61233001,61322307,and 61304196)
文摘This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the information of proximal（preceding and following） trains is used in the controller design. Based on available proximal information（prox-info） of location, speed, and acceleration, a direct adaptive control is designed to maintain the tracking interval at the minimum safe distance. Based on available prox-info of location, an observer-based adaptive control is designed to achieve the same target, which alleviates the requirements of equipped sensors to measure prox-info of speed and acceleration. The developed schemes are capable of on-line estimating of the unknown system parameters and stabilizing the closed-loop system, the string stability of train platoon is guaranteed on the basis of Lyapunov stability theorem. Numerical simulation results are presented to verify the effectiveness of the proposed control laws.
