Quantum Fisher information(QFI)associated with local metrology has been used to parameter estimation in open quantum *** this work,we calculated the QFI for a moving Unruh-DeWitt detector coupled with massless scalar ...
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Quantum Fisher information(QFI)associated with local metrology has been used to parameter estimation in open quantum *** this work,we calculated the QFI for a moving Unruh-DeWitt detector coupled with massless scalar fields in n-dimensional spacetime,and analyzed the behavior of QFI with various parameters,such as the dimension of spacetime,evolution time,and Unruh *** discovered that the QFI of state parameter decreases monotonically from 1 to 0 over ***,we noted that the QFI for small evolution times is several orders of magnitude higher than the QFI for long evolution *** also found that the value of QFI decreases at first and then stabilizes as the Unruh temperature *** was observed that the QFI depends on initial state parameterθ,and Fθis the maximum forθ=0 orθ=π,Fφis the maximum forθ=π/*** also obtain that the maximum value of QFI for state parameters varies for different spacetime dimensions with the same evolution time.
In the face of a large number of network attacks, intrusion detection system can issue early warning, indicating the emergence of network attacks. In order to improve the traditional machine learning network intrusion...
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As a kind of on-orbit servicing technology, on-orbit refueling (OOR) has essential significance in prolonging the lifetime of satellites and decreasing the generation of space debris, especially for the expensive sate...
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As a kind of on-orbit servicing technology, on-orbit refueling (OOR) has essential significance in prolonging the lifetime of satellites and decreasing the generation of space debris, especially for the expensive satellites located in geosynchronous orbit (GEO). Recently, several one-to-one mode-based OOR missions have been successfully conducted in space. To further reduce the economic cost, the mode of using several refuel satellites (RS) to refuel some dozens of client satellites (CS) in one mission has been proposed, that is, the many-to-many OOR mode. To maximize the efficiency of this mode, the mission optimization problem that determines the refueling sequence and time should be further investigated. The mission optimization is usually carried out before the OOR mission starts, and the fuel demand of CS is obtained in advance. However, the OOR mission for multiple GEO CSs usually takes a long time, and some temporarily unrefueled CSs may perform orbit maintenance by consuming the remaining fuel, leading to a time-varying fuel demand change. In this case, performing the initial mission optimization results may lead to efficiency reduction or even mission failure. To address this problem, in this paper, a many-to-many mode-based OOR mission optimization model is established considering the time-varying fuel demands, and a differential evolution (DE) based algorithm is designed to solve the problem. Firstly, a remaining fuel varying law is obtained according to the periodic orbit maintenance strategy of GEO CSs. Based on that, the mission profit model is further established. Then, by additionally considering several constraints like RS fuel capacity, mission duration, and orbital maneuver duration, the mission optimization model is established. Next, by taking the refueling sequence, the instant of refueling begins as the design variable, and a modified DE is designed to solve the problem. Unlike existing DE, a greedy-search-based mechanism generates high-qualit
The weak signal detection method based on stochastic resonance is usually used to extract and identify the weak characteristic signal submerged in strong noise by using the noise energy transfer *** propose a novel co...
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The weak signal detection method based on stochastic resonance is usually used to extract and identify the weak characteristic signal submerged in strong noise by using the noise energy transfer *** propose a novel composite multistable stochastic-resonance(NCMSR)model combining the Gaussian potential model and an improved bistable *** with the traditional multistable stochastic resonance method,all the parameters in the novel model have no symmetry,the output signal-to-noise ratio can be optimized and the output amplitude can be improved by adjusting the system *** model retains the advantages of continuity and constraint of the Gaussian potential model and the advantages of the improved bistable model without output saturation,the NCMSR model has a higher utilization of *** the output signal-to-noise ratio as the index,weak periodic signal is detected based on the NCMSR model in Gaussian noise andαnoise environment respectively,and the detection effect is *** application of NCMSR to the actual detection of bearing fault signals can realize the fault detection of bearing inner race and outer *** outstanding advantages of this method in weak signal detection are verified,which provides a theoretical basis for industrial practical applications.
In this study,we analyzed the performance of an Unmanned Aerial Vehicle(UAV)-based mixed Underwater Power Line Communication-Radio Frequency(UPLC-RF)*** this network,a buoy located at the sea is used as a relay to tra...
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In this study,we analyzed the performance of an Unmanned Aerial Vehicle(UAV)-based mixed Underwater Power Line Communication-Radio Frequency(UPLC-RF)*** this network,a buoy located at the sea is used as a relay to transmit signals from the underwater signal source to the UAV through the PLC *** assume that the UPLC channel obeys a log-normal distribution and that the RF link follows the Rician *** this model,we obtained the closed-form expressions for the Outage Probability(OP),Average Bit-error-rate(ABER),and Average Channel Capacity(ACC).In addition,the asymptotic analysis of the OP and ABER was performed,and an upper bound for the average capacity was ***,the analytical results were verified by Monte Carlo simulation thereby demonstrating the effect of impulse noise and the altitude of the UAV on network performance.
In the practical application of Brillouin optical time-domain reflectometry (BOTDR) in temperature and strain monitoring, enhancing measurement speed remains a critical challenge. This paper presents a novel method fo...
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Autonomous navigation is one of the key technologies for spacecraft to realize long-term space operation and carry out science missions. In order to meet the requirement of high precision autonomous navigation, the ef...
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In this paper,an improved sag control strategy based on automatic SOC equalization is proposed to solve the problems of slow SOC equalization and excessive bus voltage fluctuation amplitude and offset caused by load a...
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In this paper,an improved sag control strategy based on automatic SOC equalization is proposed to solve the problems of slow SOC equalization and excessive bus voltage fluctuation amplitude and offset caused by load and PV power variations in a stand-alone DC *** strategy includes primary and secondary *** them,the primary control suppresses the DC microgrid voltage fluctuation through the I and II section control,and the secondary control aims to correct the P-U curve of the energy storage system and the PV system,thus reducing the steady-state bus voltage *** simulation results demonstrate that the proposed control strategy effectively achieves SOC balancing and enhances the immunity of bus *** proposed strategy improves the voltage fluctuation suppression ability by approximately 39.4%and 43.1%under the PV power and load power fluctuation conditions,***,the steady-state deviation of the bus voltage,△U_(dc) is only 0.01–0.1 V,ensuring stable operation of the DC microgrid in fluctuating power environments.
A brain-computer interface (BCI) enables direct communication between the brain and an external device. Electroencephalogram (EEG) is the preferred input signal in non-invasive BCIs, due to its convenience and low cos...
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Aiming at the problem that the intermediate potential part of the traditional bistable stochastic resonance model cannot be adjusted independently, a new composite stochastic resonance(NCSR) model is proposed by combi...
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Aiming at the problem that the intermediate potential part of the traditional bistable stochastic resonance model cannot be adjusted independently, a new composite stochastic resonance(NCSR) model is proposed by combining the Woods–Saxon(WS) model and the improved piecewise bistable model. The model retains the characteristics of the independent parameters of WS model and the improved piecewise model has no output saturation, all the parameters in the new model have no coupling characteristics. Under α stable noise environment, the new model is used to detect periodic signal and aperiodic signal, the detection results indicate that the new model has higher noise utilization and better detection ***, the new model is applied to image denoising, the results showed that under the same conditions, the output peak signal-to-noise ratio(PSNR) and the correlation number of NCSR method is higher than that of other commonly used linear denoising methods and improved piecewise SR methods, the effectiveness of the new model is verified.
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