Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feed...Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feedback.Design/methodology/approach–A mathematical model of the PMSLM-based servo-mechanical system was first established,incorporating the aforementioned nonlinearities.The model’s velocity response was derived by analyzing its behavior as a first-order system under arbitrary input.To induce oscillatory dynamics,an ideal relay with artificially introduced dead-time components was then integrated into the servo-mechanism.Depending on the oscillations and the time-domain analysis,nonlinear formulas were deduced according to the velocity response of the servo-mechanism.Afterwards,the unknown model parameters can be solved on account of the cost function which utilizes the discrepancy between nominal position characteristics and temporary position characteristics,both of which are extracted from the oscillations.The proposed recognition method was validated through a twostage process:(1)numerical simulation and calculation,followed by(2)real-time experimental verification on a direct-drive servo platform.Subsequently,leveraging the identification results,a novel control strategy was developed and its tracking performance was benchmarked against conventional control schemes.Findings–Simulation results demonstrate that the proposed method achieves estimation accuracy within 8%.Building on this,a novel control strategy is developed by incorporating both friction pulsation and force pulsation identification results into the feedforward compensator.Comparative experiments reveal that this strategy significantly enhances tracking and positioning performance over traditional control schemes.In a word,this new identification method can be used in different process control and servo control systems.Moreover,parameter auto-tuning,feed forward compensation or disturbance observer can be investigated based on the obtained information to improve the system stability and control accuracy.Originality/value–It is of great significance for the performance improvement of rail transit motor control equipment,such as electro-mechanical braking systems.By enhancing the efficiency of motor control,the performance of the product will be more outstanding.展开更多
As the first stage of the quantum Internet,quantum key distribution(QKD)networks hold the promise of providing long-term security for diverse users.Most existing QKD networks have been constructed based on independent...As the first stage of the quantum Internet,quantum key distribution(QKD)networks hold the promise of providing long-term security for diverse users.Most existing QKD networks have been constructed based on independent QKD protocols,and they commonly rely on the deployment of single-protocol trusted relay chains for long reach.Driven by the evolution of QKD protocols,large-scale QKD networking is expected to migrate from a single-protocol to a multi-protocol paradigm,during which some useful evolutionary elements for the later stages of the quantum Internet may be incorporated.In this work,we delve into a pivotal technique for large-scale QKD networking,namely,multi-protocol relay chaining.A multi-protocol relay chain is established by connecting a set of trusted/untrusted relays relying on multiple QKD protocols between a pair of QKD nodes.The structures of diverse multi-protocol relay chains are described,based on which the associated model is formulated and the policies are defined for the deployment of multi-protocol relay chains.Furthermore,we propose three multi-protocol relay chaining heuristics.Numerical simulations indicate that the designed heuristics can effectively reduce the number of trusted relays deployed and enhance the average security level versus the commonly used single-protocol trusted relay chaining methods on backbone network topologies.展开更多
Wireless Body Area Network(WBAN)is essential for continuous health monitoring.However,they face energy efficiency challenges due to the low power consumption of sensor nodes.Current WBAN routing protocols face limitat...Wireless Body Area Network(WBAN)is essential for continuous health monitoring.However,they face energy efficiency challenges due to the low power consumption of sensor nodes.Current WBAN routing protocols face limitations in strategically minimizing energy consumption during the retrieval of vital health parameters.Efficient network traffic management remains a challenge,with existing approaches often resulting in increased delay and reduced throughput.Additionally,insufficient attention has been paid to enhancing channel capacity to maintain signal strength and mitigate fading effects under dynamic and robust operating scenarios.Several routing strategies and procedures have been developed to effectively reduce communication-related energy consumption based on the selection of relay nodes.The relay node selection is essential for data transmission in WBAN.This paper introduces an Adaptive Relay-Assisted Protocol(ARAP)for WBAN,a hybrid routing protocol designed to optimize energy use and Quality of Service(QoS)metrics such as network longevity,latency,throughput,and residual energy.ARAP employs neutrosophic relay node selection techniques,including the Analytic Hierarchy Process(AHP)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to optimally resolve data and decision-making uncertainties.The protocol was compared with existing protocols such as Low-Energy Adaptive Clustering Hierarchy(LEACH),Modified-Adaptive Threshold Testing and Evaluation Methodology for Performance Testing(M-ATTEMPT),Wireless Adaptive Sampling Protocol(WASP),and Tree-Based Multicast Quality of Service(TMQoS).The comparative results show that the ARAP significantly outperformed these protocols in terms of network longevity and energy efficiency.ARAP has lower communication cost,better throughput,reduced delay,increased network lifetime,and enhanced residual energy.The simulation results indicate that the proposed approach performed better than the conventional methods,with 68%,62%,25%,and 50%improvements in network longevity,residual energy,throughput,and latency,respectively.This significantly improves the functional lifespan of WBAN and makes them promising candidates for sophisticated health monitoring systems.展开更多
In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances...In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances.Hence,PLC networks often employ repeaters/relays,especially in smart grid neighborhood area networks.Even in broadband indoor PLC systems that offer a notable data rate,relaying may pave the way to new applications like being the backbone for wireless technologies in a cost-effective manner to support the Internet-of-things paradigm.In this paper,we study Multiple-Input Multiple-Output(MIMO)PLC systems that incorporate inband full-duplex functionality in relaying networks.We present several MIMO configurations that allow end-to-end half-duplex or full-duplex operations and analyze the achievable performance with state-of-the-art PLC systems.To reach this analysis,we get channel realizations from random network layouts for indoor and outdoor scenarios.We adopt realistic MIMO channel and noise models and consider transmission techniques according to PLC standards.The concepts discussed in this work can be useful in the design of future PLC relay-aided networks for different applications that look for a coverage extension and/or throughput:smart grids with enhanced communications in outdoor scenarios,and“last meter”systems for high-speed connections everywhere in indoor ones.展开更多
Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protectio...Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protection simultaneously,which limits the applicability.To address this,an innovative bi-layered coating with organic/nano-inorganic additives is inspired by differential response behaviors,enabling relay response effect with both fast-acting and extended protection.Specifically,two layers function continuously in the form of a relay.With a mere 320 microns,the bi-layered coating withstands fire temperatures of up to 1400℃for at least 900 s.Consequently,the coating effective prevented burn through in aluminum plates and glass fabric-reinforced epoxy resin,which otherwise were burned through in 135 and 173 s,respectively.Meanwhile,the bi-layered coating suppressed the formation and decomposition of solid interface layer in lithium soft-package batteries,leading to prolonged electrochemical stability and fire safety.Additionally,the bi-layered coating with a fast response endows polyurethane foam with rapid self-extinguishing,preventing ignition even under exposure to strong fire of 1400℃.Shortly,our work offers new insights into the design and development of thin,high-performance,and multi-application flame-retardant coatings.展开更多
An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactone...An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.展开更多
The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless cove...The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless coverage.Unmanned Aerial Vehicles(UAVs),serving as high-mobility aerial platforms,are extensively utilized to enhance coverage in long-distance emergency communication scenarios.The resource-constrained communication environments in emergencies by classifying UAVs into swarm UAVs and relay UAVs as aerial communication nodes is inversitgated.A horizontal deployment strategy for swarm UAVs is formulated through K-means clustering algorithm optimization,while a vertical deployment scheme is established using convex optimization methods.The minimum-path trajectory planning for relay UAVs is optimized via the Particle Swarm Optimization(PSO)algorithm,enhancing communication reliability between UAV swarms and terrestrial base stations.A three-dimensional heterogeneous network architecture is realized by modeling spatial multi-hop relay links.Experimental results demonstrate that the proposed joint UAV relay optimization framework outperforms conventional algorithms in both coverage performance and relay capability during video stream transmission,achieving significant improvements in coverage enhancement and relay efficiency.This work provides technical foundations for constructing high-reliability air-ground cooperative systems in emergency communications.展开更多
This paper is concerned with design-ing symbol labeling for a low-density parity-check(LDPC)-coded delayed bit-interleaved coded modu-lation(DBICM)scheme in a two-way relay channel(TWRC).We first present some properti...This paper is concerned with design-ing symbol labeling for a low-density parity-check(LDPC)-coded delayed bit-interleaved coded modu-lation(DBICM)scheme in a two-way relay channel(TWRC).We first present some properties of symbol labeling within a phase shift keying(PSK)modula-tion.These properties reduce the candidate labeling search space.Based on this search space,we take DBICM capacity as the cost function and propose a general method for optimizing symbol labeling by em-ploying the differential evolution algorithm.Numeri-cal results show that our labeling obtains a signal-to-noise ratio(SNR)gain up to 0.45 dB with respect to Gray labeling.展开更多
Wireless communications in extreme environments,such as underwater and underground,is an essential technology for interconnecting various devices and enables data transmission and networking.Existing wireless technolo...Wireless communications in extreme environments,such as underwater and underground,is an essential technology for interconnecting various devices and enables data transmission and networking.Existing wireless technologies using electromagnetic(EM)waves face many known problems,such as high path loss,unpredictable multi-path fading,and large antenna size in the lossy medium.In this article,the magnetic induction(MI)based physical layer communication is introduced as a promising solution for wireless transmissions in extreme environments.Specifically,the fundamentals of the MI-based communications are reviewed.Then,with the goal of establishing reliable and low-power links between small-size devices,we review several key physical layer technologies for MI-based communications,including the MIbased signal modulations,magnetic beamforming,and relay transmissions,and summarize their state-of-theart research advances.Finally,the related open issues and challenges in each area are analyzed and presented for future investigations.展开更多
In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220...In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.展开更多
A novel photocatalytic energy transfer-driven radical relay strategy has been introduced for the chemoand regioselective 1,4-difunctionalization of carbon-sulfur double bonds.This represents the first instance of radi...A novel photocatalytic energy transfer-driven radical relay strategy has been introduced for the chemoand regioselective 1,4-difunctionalization of carbon-sulfur double bonds.This represents the first instance of radical-mediated dual-functionalization of X-Y type unsaturated bonds,enabling the synthesis of complex linear molecules with C–O,C–N,and C-S bonds in a single operation.The method surpasses traditional approaches by avoiding the need for thiourea intermediates and the harsh conditions typically associated with them.The developed strategy exemplifies versatility,being applicable to 1,4-oxyamination,1,4-diamination,and 1,4-sulfonamination reactions,and has demonstrated compatibility with over 60 different substrates.The research also elucidates the role of electronic complementarity between radicals and receptors in achieving high selectivity in 1,4-difunctionalization reactions.This study significantly advances the field of bifunctionalization and remote difunctionalization reactions,with profound implications for the development of pharmaceuticals and materials science.展开更多
Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuato...Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.展开更多
This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying tec...This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying techniques are utilized to enhance secrecy performance. By jointly optimizing the link selection strategy, the UAV position, and the reflection coefficient of the IRS, we aim to maximize the long-term average secrecy rate. Specifically, we propose a novel buffer in/out stabilization scheme based on the Lyapunov framework, which transforms the long-term average secrecy rate maximization problem into two per-slot drift-plus-penalty minimization problems with different link selection factors. The hybrid Particle Swarm Optimization-Artificial Fish Swarm Algorithm (PSO-AFSA) is adopted to optimize the UAV position, and the IRS reflection coefficient optimization problem is solved by iterative optimization in which auxiliary variables and standard convex optimization algorithms are introduced. Finally, the delay constraint is set to ensure the timeliness of information packets. Simulation results demonstrate that our proposed scheme outperforms the comparison schemes in terms of average secrecy rate. Specifically, the addition of BA improves the average secrecy rate by 1.37 bps/Hz, and the continued optimizations of IRS reflection coefficients and UAV positions improve the average secrecy rate by 2.46 bps/Hz and 3.75 bps/Hz, respectively.展开更多
In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-...In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.展开更多
In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been ...In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been unable to meet the development trend of fast-response,miniaturized,and lightweight aerospace and aviation systems.This paper applies circuit theory and electromagnetics theory to establish a Field-Circuit Coupling Mathematical Model(FCCMM)for dynamic response analysis of HSERs.This model centers on inductance calculation,with the core's permeability and saturation magnetic flux density as critical parameters.Based on this model,for a specific type of HSER,this paper introduced three alloys with key parameters different from magnetic iron,then tested the magnetic characteristic curves of these four soft magnetic materials,followed by simulations to obtain the electromagnetic characteristics of digital mock-ups corresponding to these four materials,compared and validated the dynamic responses corresponding to these four soft magnetic materials finally.Based on the theoretical model analysis results,this paper designed a lightweight coil to minimize response time,made prototypes,set up test systems,and tested dynamic characteristics.The experimental results indicate that the nanocrystalline alloy1K107B exhibits the most significant optimization,reducing the closing time by 40.48%and achieving a weight reduction of 6.53%.展开更多
Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed th...Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed that the global channel state information(CSI)of the eavesdroppers(Eves)was known beforehand,then the optimal relaying and jamming relays were determined.More importantly,the time complexity of selecting optimal jamming relay is O(N^(2)),where N is the maximum number of relays/Eves.In this paper,for the scenario where the source wants to exchange the message with the destination,via relaying scheme due to longer communication distance and limited transmission power,in the presence of multiple Eves,with the assumption of Eves'perfect CSI and average CSI,we propose two kinds of JRJS methods.In particular,the time complexity of finding the optimal jammer can be reduced to O(N).Furthermore,we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination.Finally,simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.展开更多
In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems w...In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems within dynamic and complex communication environ-ments.By formulating the relay selection problem as a Markov decision process(MDP),the DQN algorithm employs deep neural networks(DNNs)to learn and make decisions through real-time interactions with the communication environment,aiming to minimize the system’s outage proba-bility.During the learning process,the DQN algorithm progressively acquires channel state infor-mation(CSI)between two nodes,thereby minimizing the system’s outage probability until a sta-ble level is reached.Simulation results show that the proposed method effectively reduces the out-age probability by 82%compared to the two-way relay selection scheme(Two-Way)when the sig-nal-to-noise ratio(SNR)is 30 dB.This study demonstrates the applicability and advantages of the DQN algorithm in cooperative NOMA systems,providing a novel approach to addressing real-time relay selection challenges in dynamic communication environments.展开更多
Closed-form bounds for the end-to-end performance of multihop communications with non-regenerative relays over Nakagami-m fading channels are investigated.Upper and lower bounds of the end-to-end signal-to-noise ratio...Closed-form bounds for the end-to-end performance of multihop communications with non-regenerative relays over Nakagami-m fading channels are investigated.Upper and lower bounds of the end-to-end signal-to-noise ratio(SNR)are first developed by using the monotonicity.Then,the probability density functions(PDFs),the cumulative distribution functions,and the momentgenerating functions(MGFs)of the bounds are derived.Using these results,the bounds for the outage and average bit error probability(ABEP)are obtained.Numerical and simulation results are executed to validate the tightness of the proposed bounds.展开更多
Hermetically Sealed Electromagnetic Relay(HSER), used in aviation and aerospace,demands high reliability due to its critical applications. Given its complex operating conditions, efficient thermal analysis is essentia...Hermetically Sealed Electromagnetic Relay(HSER), used in aviation and aerospace,demands high reliability due to its critical applications. Given its complex operating conditions, efficient thermal analysis is essential for optimizing reliability. The commonly used Finite Element Method(FEM) is often time-consuming and may not be efficient or adaptable for complex multi-dimensional system calculations and design processes. This paper introduces an analysis method for thermal networks based on matrix perspective technology, encompassing matrix transformation, backpropagation of the heat path model, temperature rise calculation, solution comparison, and product implementation. Using the similarity theory of heat circuits, a basic thermal unit is established. Based on the fundamental connection between key components, a thermal network for a typical HSER is designed. An experimental system is set up, and the thermal network model's accuracy is confirmed using test data. Employing the topology analysis method, the topology of the thermal network is analyzed under both coil-energized and de-energized states. Potential thermal paths are identified, leading to optimized solutions for the HSER. Utilizing these solutions, the thermal path matrix topology model is backpropagated to the thermal path for temperature rise calculations. When compared to prototype HSER test data, the efficiency and accuracy of this matrix topology-based analysis method are confirmed.展开更多
In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of sci...In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2,including mission orbit and transfer orbit design,configuration and layout design,housekeeping and information flow design,power supply and distribution design,GNC and propulsion system design,communication links design,etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity,availability,schedule,cost,and so on.With a view to reducing development risk,both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies,modulations,data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20,2024,by means of 5 orbit maneuvers,Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations,Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions,as well as the capacity to perform scientific observations.Under the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far side.In the meanwhile,Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design,it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition,innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture,multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching,orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2,more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.展开更多
文摘Purpose–This study aims to propose a novel identification method to accurately estimate linear and nonlinear dynamics in permanent magnet synchronous linear motor(PMSLM)based on the time-domain analysis of relay feedback.Design/methodology/approach–A mathematical model of the PMSLM-based servo-mechanical system was first established,incorporating the aforementioned nonlinearities.The model’s velocity response was derived by analyzing its behavior as a first-order system under arbitrary input.To induce oscillatory dynamics,an ideal relay with artificially introduced dead-time components was then integrated into the servo-mechanism.Depending on the oscillations and the time-domain analysis,nonlinear formulas were deduced according to the velocity response of the servo-mechanism.Afterwards,the unknown model parameters can be solved on account of the cost function which utilizes the discrepancy between nominal position characteristics and temporary position characteristics,both of which are extracted from the oscillations.The proposed recognition method was validated through a twostage process:(1)numerical simulation and calculation,followed by(2)real-time experimental verification on a direct-drive servo platform.Subsequently,leveraging the identification results,a novel control strategy was developed and its tracking performance was benchmarked against conventional control schemes.Findings–Simulation results demonstrate that the proposed method achieves estimation accuracy within 8%.Building on this,a novel control strategy is developed by incorporating both friction pulsation and force pulsation identification results into the feedforward compensator.Comparative experiments reveal that this strategy significantly enhances tracking and positioning performance over traditional control schemes.In a word,this new identification method can be used in different process control and servo control systems.Moreover,parameter auto-tuning,feed forward compensation or disturbance observer can be investigated based on the obtained information to improve the system stability and control accuracy.Originality/value–It is of great significance for the performance improvement of rail transit motor control equipment,such as electro-mechanical braking systems.By enhancing the efficiency of motor control,the performance of the product will be more outstanding.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62201276,62350001,U22B2026,and 62471248)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300701)+1 种基金the Key R&D Program(Industry Foresight and Key Core Technologies)of Jiangsu Province(Grant No.BE2022071)Natural Science Research of Jiangsu Higher Education Institutions of China(Grant No.22KJB510007)。
文摘As the first stage of the quantum Internet,quantum key distribution(QKD)networks hold the promise of providing long-term security for diverse users.Most existing QKD networks have been constructed based on independent QKD protocols,and they commonly rely on the deployment of single-protocol trusted relay chains for long reach.Driven by the evolution of QKD protocols,large-scale QKD networking is expected to migrate from a single-protocol to a multi-protocol paradigm,during which some useful evolutionary elements for the later stages of the quantum Internet may be incorporated.In this work,we delve into a pivotal technique for large-scale QKD networking,namely,multi-protocol relay chaining.A multi-protocol relay chain is established by connecting a set of trusted/untrusted relays relying on multiple QKD protocols between a pair of QKD nodes.The structures of diverse multi-protocol relay chains are described,based on which the associated model is formulated and the policies are defined for the deployment of multi-protocol relay chains.Furthermore,we propose three multi-protocol relay chaining heuristics.Numerical simulations indicate that the designed heuristics can effectively reduce the number of trusted relays deployed and enhance the average security level versus the commonly used single-protocol trusted relay chaining methods on backbone network topologies.
文摘Wireless Body Area Network(WBAN)is essential for continuous health monitoring.However,they face energy efficiency challenges due to the low power consumption of sensor nodes.Current WBAN routing protocols face limitations in strategically minimizing energy consumption during the retrieval of vital health parameters.Efficient network traffic management remains a challenge,with existing approaches often resulting in increased delay and reduced throughput.Additionally,insufficient attention has been paid to enhancing channel capacity to maintain signal strength and mitigate fading effects under dynamic and robust operating scenarios.Several routing strategies and procedures have been developed to effectively reduce communication-related energy consumption based on the selection of relay nodes.The relay node selection is essential for data transmission in WBAN.This paper introduces an Adaptive Relay-Assisted Protocol(ARAP)for WBAN,a hybrid routing protocol designed to optimize energy use and Quality of Service(QoS)metrics such as network longevity,latency,throughput,and residual energy.ARAP employs neutrosophic relay node selection techniques,including the Analytic Hierarchy Process(AHP)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to optimally resolve data and decision-making uncertainties.The protocol was compared with existing protocols such as Low-Energy Adaptive Clustering Hierarchy(LEACH),Modified-Adaptive Threshold Testing and Evaluation Methodology for Performance Testing(M-ATTEMPT),Wireless Adaptive Sampling Protocol(WASP),and Tree-Based Multicast Quality of Service(TMQoS).The comparative results show that the ARAP significantly outperformed these protocols in terms of network longevity and energy efficiency.ARAP has lower communication cost,better throughput,reduced delay,increased network lifetime,and enhanced residual energy.The simulation results indicate that the proposed approach performed better than the conventional methods,with 68%,62%,25%,and 50%improvements in network longevity,residual energy,throughput,and latency,respectively.This significantly improves the functional lifespan of WBAN and makes them promising candidates for sophisticated health monitoring systems.
基金supported by the Spanish Government and EU,under project PID2019-109842RB-I00/AEI/10.13039/501100011033。
文摘In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances.Hence,PLC networks often employ repeaters/relays,especially in smart grid neighborhood area networks.Even in broadband indoor PLC systems that offer a notable data rate,relaying may pave the way to new applications like being the backbone for wireless technologies in a cost-effective manner to support the Internet-of-things paradigm.In this paper,we study Multiple-Input Multiple-Output(MIMO)PLC systems that incorporate inband full-duplex functionality in relaying networks.We present several MIMO configurations that allow end-to-end half-duplex or full-duplex operations and analyze the achievable performance with state-of-the-art PLC systems.To reach this analysis,we get channel realizations from random network layouts for indoor and outdoor scenarios.We adopt realistic MIMO channel and noise models and consider transmission techniques according to PLC standards.The concepts discussed in this work can be useful in the design of future PLC relay-aided networks for different applications that look for a coverage extension and/or throughput:smart grids with enhanced communications in outdoor scenarios,and“last meter”systems for high-speed connections everywhere in indoor ones.
基金the support by the National Natural Science Foundation of China(grant numbers 52273048 and 51973006)the Beijing Natural Science Foundation of China(grant number 2222052)the financial support of this work by BIOFIRESAFE(PID2020-117274RB-I00)funded by MINECO,Spain。
文摘Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protection simultaneously,which limits the applicability.To address this,an innovative bi-layered coating with organic/nano-inorganic additives is inspired by differential response behaviors,enabling relay response effect with both fast-acting and extended protection.Specifically,two layers function continuously in the form of a relay.With a mere 320 microns,the bi-layered coating withstands fire temperatures of up to 1400℃for at least 900 s.Consequently,the coating effective prevented burn through in aluminum plates and glass fabric-reinforced epoxy resin,which otherwise were burned through in 135 and 173 s,respectively.Meanwhile,the bi-layered coating suppressed the formation and decomposition of solid interface layer in lithium soft-package batteries,leading to prolonged electrochemical stability and fire safety.Additionally,the bi-layered coating with a fast response endows polyurethane foam with rapid self-extinguishing,preventing ignition even under exposure to strong fire of 1400℃.Shortly,our work offers new insights into the design and development of thin,high-performance,and multi-application flame-retardant coatings.
基金financial supports for this work are provided by the National Natural Science Foundation of China(Nos.21871160,21672121,22071130)。
文摘An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.
文摘The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless coverage.Unmanned Aerial Vehicles(UAVs),serving as high-mobility aerial platforms,are extensively utilized to enhance coverage in long-distance emergency communication scenarios.The resource-constrained communication environments in emergencies by classifying UAVs into swarm UAVs and relay UAVs as aerial communication nodes is inversitgated.A horizontal deployment strategy for swarm UAVs is formulated through K-means clustering algorithm optimization,while a vertical deployment scheme is established using convex optimization methods.The minimum-path trajectory planning for relay UAVs is optimized via the Particle Swarm Optimization(PSO)algorithm,enhancing communication reliability between UAV swarms and terrestrial base stations.A three-dimensional heterogeneous network architecture is realized by modeling spatial multi-hop relay links.Experimental results demonstrate that the proposed joint UAV relay optimization framework outperforms conventional algorithms in both coverage performance and relay capability during video stream transmission,achieving significant improvements in coverage enhancement and relay efficiency.This work provides technical foundations for constructing high-reliability air-ground cooperative systems in emergency communications.
文摘This paper is concerned with design-ing symbol labeling for a low-density parity-check(LDPC)-coded delayed bit-interleaved coded modu-lation(DBICM)scheme in a two-way relay channel(TWRC).We first present some properties of symbol labeling within a phase shift keying(PSK)modula-tion.These properties reduce the candidate labeling search space.Based on this search space,we take DBICM capacity as the cost function and propose a general method for optimizing symbol labeling by em-ploying the differential evolution algorithm.Numeri-cal results show that our labeling obtains a signal-to-noise ratio(SNR)gain up to 0.45 dB with respect to Gray labeling.
文摘Wireless communications in extreme environments,such as underwater and underground,is an essential technology for interconnecting various devices and enables data transmission and networking.Existing wireless technologies using electromagnetic(EM)waves face many known problems,such as high path loss,unpredictable multi-path fading,and large antenna size in the lossy medium.In this article,the magnetic induction(MI)based physical layer communication is introduced as a promising solution for wireless transmissions in extreme environments.Specifically,the fundamentals of the MI-based communications are reviewed.Then,with the goal of establishing reliable and low-power links between small-size devices,we review several key physical layer technologies for MI-based communications,including the MIbased signal modulations,magnetic beamforming,and relay transmissions,and summarize their state-of-theart research advances.Finally,the related open issues and challenges in each area are analyzed and presented for future investigations.
文摘In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.
基金the National Natural Science Foundation of China(No.22101059)the financial support from Guangxi Science and Technology Program of China(No.2023GXNSFBA026275)Guangxi Normal University。
文摘A novel photocatalytic energy transfer-driven radical relay strategy has been introduced for the chemoand regioselective 1,4-difunctionalization of carbon-sulfur double bonds.This represents the first instance of radical-mediated dual-functionalization of X-Y type unsaturated bonds,enabling the synthesis of complex linear molecules with C–O,C–N,and C-S bonds in a single operation.The method surpasses traditional approaches by avoiding the need for thiourea intermediates and the harsh conditions typically associated with them.The developed strategy exemplifies versatility,being applicable to 1,4-oxyamination,1,4-diamination,and 1,4-sulfonamination reactions,and has demonstrated compatibility with over 60 different substrates.The research also elucidates the role of electronic complementarity between radicals and receptors in achieving high selectivity in 1,4-difunctionalization reactions.This study significantly advances the field of bifunctionalization and remote difunctionalization reactions,with profound implications for the development of pharmaceuticals and materials science.
基金National Natural Science Foundation of China(62203118)。
文摘Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.
基金co-supported by the National Natural Science Foundation of China(Nos.62271399,61901015,GNA22001 and GAA20024)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F010003).
文摘This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying techniques are utilized to enhance secrecy performance. By jointly optimizing the link selection strategy, the UAV position, and the reflection coefficient of the IRS, we aim to maximize the long-term average secrecy rate. Specifically, we propose a novel buffer in/out stabilization scheme based on the Lyapunov framework, which transforms the long-term average secrecy rate maximization problem into two per-slot drift-plus-penalty minimization problems with different link selection factors. The hybrid Particle Swarm Optimization-Artificial Fish Swarm Algorithm (PSO-AFSA) is adopted to optimize the UAV position, and the IRS reflection coefficient optimization problem is solved by iterative optimization in which auxiliary variables and standard convex optimization algorithms are introduced. Finally, the delay constraint is set to ensure the timeliness of information packets. Simulation results demonstrate that our proposed scheme outperforms the comparison schemes in terms of average secrecy rate. Specifically, the addition of BA improves the average secrecy rate by 1.37 bps/Hz, and the continued optimizations of IRS reflection coefficients and UAV positions improve the average secrecy rate by 2.46 bps/Hz and 3.75 bps/Hz, respectively.
基金funded by the Deanship of Graduate Studies and Scientific Research at Jouf University under grant No.(DGSSR-2024-02-02160).
文摘In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.
基金supported by the National Natural Science Foundation of China(No.52177134)。
文摘In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been unable to meet the development trend of fast-response,miniaturized,and lightweight aerospace and aviation systems.This paper applies circuit theory and electromagnetics theory to establish a Field-Circuit Coupling Mathematical Model(FCCMM)for dynamic response analysis of HSERs.This model centers on inductance calculation,with the core's permeability and saturation magnetic flux density as critical parameters.Based on this model,for a specific type of HSER,this paper introduced three alloys with key parameters different from magnetic iron,then tested the magnetic characteristic curves of these four soft magnetic materials,followed by simulations to obtain the electromagnetic characteristics of digital mock-ups corresponding to these four materials,compared and validated the dynamic responses corresponding to these four soft magnetic materials finally.Based on the theoretical model analysis results,this paper designed a lightweight coil to minimize response time,made prototypes,set up test systems,and tested dynamic characteristics.The experimental results indicate that the nanocrystalline alloy1K107B exhibits the most significant optimization,reducing the closing time by 40.48%and achieving a weight reduction of 6.53%.
基金supported by the National Natural Science Foundation of China with Grants 62301076 and 62321001。
文摘Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed that the global channel state information(CSI)of the eavesdroppers(Eves)was known beforehand,then the optimal relaying and jamming relays were determined.More importantly,the time complexity of selecting optimal jamming relay is O(N^(2)),where N is the maximum number of relays/Eves.In this paper,for the scenario where the source wants to exchange the message with the destination,via relaying scheme due to longer communication distance and limited transmission power,in the presence of multiple Eves,with the assumption of Eves'perfect CSI and average CSI,we propose two kinds of JRJS methods.In particular,the time complexity of finding the optimal jammer can be reduced to O(N).Furthermore,we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination.Finally,simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.
基金supported by the National Natural Science Foundation of China(Nos.61841107 and 62061024)Gansu Natural Sci-ence Foundation(Nos.22JR5RA274 and 23YFGA0062)Gansu Innovation Foundation(No.2022A-215).
文摘In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems within dynamic and complex communication environ-ments.By formulating the relay selection problem as a Markov decision process(MDP),the DQN algorithm employs deep neural networks(DNNs)to learn and make decisions through real-time interactions with the communication environment,aiming to minimize the system’s outage proba-bility.During the learning process,the DQN algorithm progressively acquires channel state infor-mation(CSI)between two nodes,thereby minimizing the system’s outage probability until a sta-ble level is reached.Simulation results show that the proposed method effectively reduces the out-age probability by 82%compared to the two-way relay selection scheme(Two-Way)when the sig-nal-to-noise ratio(SNR)is 30 dB.This study demonstrates the applicability and advantages of the DQN algorithm in cooperative NOMA systems,providing a novel approach to addressing real-time relay selection challenges in dynamic communication environments.
基金This work was supported by the National Basic Research Program of China(Nos.2007CB310604 and 2009CB320401)the National Natural Science Foundation of China(Grant No.60772108).
文摘Closed-form bounds for the end-to-end performance of multihop communications with non-regenerative relays over Nakagami-m fading channels are investigated.Upper and lower bounds of the end-to-end signal-to-noise ratio(SNR)are first developed by using the monotonicity.Then,the probability density functions(PDFs),the cumulative distribution functions,and the momentgenerating functions(MGFs)of the bounds are derived.Using these results,the bounds for the outage and average bit error probability(ABEP)are obtained.Numerical and simulation results are executed to validate the tightness of the proposed bounds.
基金supported by the National Natural Science Foundation of China (No. 52177134)。
文摘Hermetically Sealed Electromagnetic Relay(HSER), used in aviation and aerospace,demands high reliability due to its critical applications. Given its complex operating conditions, efficient thermal analysis is essential for optimizing reliability. The commonly used Finite Element Method(FEM) is often time-consuming and may not be efficient or adaptable for complex multi-dimensional system calculations and design processes. This paper introduces an analysis method for thermal networks based on matrix perspective technology, encompassing matrix transformation, backpropagation of the heat path model, temperature rise calculation, solution comparison, and product implementation. Using the similarity theory of heat circuits, a basic thermal unit is established. Based on the fundamental connection between key components, a thermal network for a typical HSER is designed. An experimental system is set up, and the thermal network model's accuracy is confirmed using test data. Employing the topology analysis method, the topology of the thermal network is analyzed under both coil-energized and de-energized states. Potential thermal paths are identified, leading to optimized solutions for the HSER. Utilizing these solutions, the thermal path matrix topology model is backpropagated to the thermal path for temperature rise calculations. When compared to prototype HSER test data, the efficiency and accuracy of this matrix topology-based analysis method are confirmed.
文摘In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2,including mission orbit and transfer orbit design,configuration and layout design,housekeeping and information flow design,power supply and distribution design,GNC and propulsion system design,communication links design,etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity,availability,schedule,cost,and so on.With a view to reducing development risk,both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies,modulations,data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20,2024,by means of 5 orbit maneuvers,Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations,Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions,as well as the capacity to perform scientific observations.Under the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far side.In the meanwhile,Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design,it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition,innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture,multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching,orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2,more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.
