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Hybrid cavity-iodine-locked optical frequency reference with 3×10-15 instability across six decades 认领 引用
1
作者 QIYUE WU ZHIYUAN WANG +11 位作者 ZHENQI ZHANG JIALU CHANG XINGYUE LIU SIQI WU JINGXUAN ZHANG QIANG WEI XIAOXU CHEN YANFANG YI XIAOJIE WANG KE DENG ZEHUANG LU JIE ZHANG 《Photonics Research》 SCIE EI CAS CSCD 2026年第6期2722-2730,共9页
Optical frequency references with excellent frequency stability have wide applications in precision measurement fields.In this paper,we demonstrate an ultra-stable laser source with excellent performance based on the ... Optical frequency references with excellent frequency stability have wide applications in precision measurement fields.In this paper,we demonstrate an ultra-stable laser source with excellent performance based on the hybrid locking of a Fabry-Perot(FP)cavity and molecular iodine.We develop a theoretical hybrid locking model and implement its derived control scheme,achieving an operation independent of external frequency references.Based on the electro-optic frequency comb(EOFC)composed of an electro-optic modulator,we lock the laser frequency to the two references simultaneously,enabling the laser frequency to have the stability advantages of both references and providing an absolute frequency reference.The aliasing noise arising from residual noise after cavity pre-stabilization in the hybrid locking loop is investigated and suppressed.The measured fractional frequency instability of the laser reaches about 3×10-15 across six decades of averaging time,from 0.1 s to 105 s.The frequency drift rate reaches 1.3×10-19s-1.Designed for space applications,this optical frequency reference is a promising candidate for future space-based frequency standards. 展开更多
关键词 molecular iodinewe fractional frequency instability Fabry Perot cavity hybrid locking precision measurement molecular iodine optical frequency references electro optic frequency comb
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Ultra-broadband and high-dynamic-range photonic analog-to-digital converter via 24-channel dense frequency interleaving 认领 引用
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作者 JIANWEI LIU WEICHAO MA +6 位作者 JINGWEN DONG WEN JIANG CHENYU LIU SHENDA ZHANG JIYAO YANG RUIXUAN WANG WANGZHE LI 《Photonics Research》 SCIE EI CAS CSCD 2026年第6期2457-2468,共12页
Photonic frequency interleaving(PFI)has emerged as a key enabling technique for ultra-broadband signal acquisition,with the potential to overcome channel mismatch and clock jitter that fundamentally limit timeinterlea... Photonic frequency interleaving(PFI)has emerged as a key enabling technique for ultra-broadband signal acquisition,with the potential to overcome channel mismatch and clock jitter that fundamentally limit timeinterleaved analog-to-digital converters(ADCs).However,existing PFI schemes face trade-offs among acquisition bandwidth,spectral slicing density,and inter-channel isolation,hindering the concurrent achievement of wide bandwidth and high fidelity.In this work,we propose and experimentally demonstrate a dense photonic-frequency-interleaved(DPFI)ADC architecture featuring ultra-broadband operation and high spurious-free dynamic range(SFDR).By incorporating wavelength-division multiplexing,the proposed scheme greatly increases spectral slicing density and the channel count while maintaining high inter-channel isolation.Restricting each sub-ADC to a sub-2-GHz sampling bandwidth markedly improves SFDR and relaxes the stringent jitter requirement of the sampling clock.In a proof-of-concept experiment,a 24-channel DPFI-ADC achieves a total acquisition bandwidth of 72 GHz and an SFDR of 62.9 dB at 68.38 GHz.The broadband acquisition of an 11.8-GHz linear-frequency-modulated waveform and a 1024QAM signal further validates the application potential of the proposed scheme.To the best of our knowledge,our work demonstrates the first frequency-interleaved-ADC with such massive spectral interleaving and record-high SFDR performance,which state-of-the-art electronic ADCs can only achieve at bandwidths below 10 GHz. 展开更多
关键词 High dynamic range Ultra broadband photonic frequency interleaving pfi Photonic frequency interleaving clock jitter Photonic analog digital converter channel dense frequency interleaving channel mismatch
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Frequency measurement and analysis via different frequency phase synchronization fuzzy region 认领 引用
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作者 DU Baoqiang WANG Xiang YAO Dunzhi 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2026年第2期219-231,共13页
A precise frequency measurement and analysis method utilizing the concept of the different frequency phase synchronization fuzzy region is presented based on the principle of phase synchronization detection.Initially,... A precise frequency measurement and analysis method utilizing the concept of the different frequency phase synchronization fuzzy region is presented based on the principle of phase synchronization detection.Initially,the frequency of the measured signal was roughly estimated by using the traditional high-precision time and frequency detection technology.Subsequently,the frequency estimated was fed into a direct digital synthesizer(DDS)to generate a real-time frequency standard signal that exhibited a slight frequency deviation relative to the measured signal.The edge pulses of the different frequency phase synchronization fuzzy region served as counter switch signals,enabling the counting of both the detected signal and the real-time frequency standard signal within a specified gate time.Through subsequent data processing of the obtained values,the frequency,frequency difference,and frequency accuracy of the detected signal could be determined.Experimental results demonstrate that the system based on this method achieves a frequency stability of 10−13 at 1 s,with a frequency deviation of less than 3 Hz.Compared with traditional frequency measurement and analysis methods,this approach has many advantages,especially its fast response time of less than 1 ms,high measurement accuracy of more than 10−11 at 1 s,high integration with only one FPGA chip,and cost of less than 1000 yuan.It is widely applied in the fields of time and frequency services and security technology of the Beidou satellite(BDS)navigation system,such as BDS pseudo-range measurement,Beidou positioning,navigation and time services,as well as precise time and frequency measurement and control,etc. 展开更多
关键词 different frequency phase synchronization frequency analysis and measurement frequency accuracy phase synchronization fuzzy region frequency stability group period
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The impact of increased renewable energy penetration and reduced inertia on the frequency nadir in a multi-area interconnected network based on the peninsula Malaysia national grid 认领 引用
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作者 Ousama M.T.Ajami Maadh S.J.Alkhusaibi +2 位作者 Rodney H.G.Tan Farah Adilah Jamaludin Mithulananthan Nadarajah 《Global Energy Interconnection》 EI CSCD 2026年第2期372-385,共14页
The increased adoption of renewable energy sources(RES)has left the power system grid with ever more decreasing inertia.The inertia plays a crucial part in mitigating frequency changes in the power system.Nevertheless... The increased adoption of renewable energy sources(RES)has left the power system grid with ever more decreasing inertia.The inertia plays a crucial part in mitigating frequency changes in the power system.Nevertheless,the extent how which the reduction of inertia affects an interconnected power system has not been studied,specifically the frequency nadir parameter.In this research,the effects of increasing RES penetration and the consecutive reduction in inertia have been studied,and their impact on the frequency nadir was investigated.A transfer function model of the power system frequency was developed based on the Malaysian peninsula interconnected grid,consisting of four regions.Four scenarios were tested,each of which focused on a specific region with varying levels of load disturbances and RES penetration levels.A performance metric,mFD,was proposed to measure the sensitivity of frequency nadir with different contingency levels at varying RE penetration.The scenarios demonstrated the nonlinear relation between the increase of RE and the frequency nadir.Furthermore,the relation of disturbance magnitude and frequency nadir was determined to be linear.The scenarios demonstrated the role of higher inertia regions in mitigating the effects of contingencies propagating to other regions.Moreover,regions with low inertia and higher interconnections showed more resilience when the contingency occurred outside their area.Conversely,they showed a higher risk for the system when the inertia happens within them.The results show the importance of maintaining inertia in high inertia grids and increasing it in lower inertia grids. 展开更多
关键词 Load frequency control Frequency nadir Power system inertia Frequency stability
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Multi-Dimensional Collaborative Optimization Strategy for Control Parameters of Thermal-Energy Storage Integrated Systems Considering Frequency Regulation Losses 认领 引用
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作者 Zezhong Liu Jinyu Guo +1 位作者 Xingxu Zhu Junhui Li 《Energy Engineering》 EI 2026年第3期361-390,共30页
With the increasing penetration of renewable energy,the coordination of energy storage with thermal power for frequency regulation has become an effective means to enhance grid frequency security.Addressing the challe... With the increasing penetration of renewable energy,the coordination of energy storage with thermal power for frequency regulation has become an effective means to enhance grid frequency security.Addressing the challenge of improving the frequency regulation performance of a thermal-storage primary frequency regulation system while reducing its associated losses,this paper proposes a multi-dimensional cooperative optimization strategy for the control parameters of a combined thermal-storage system,considering regulation losses.First,the frequency regulation losses of various components within the thermal power unit are quantified,and a calculation method for energy storage regulation loss is proposed,based on Depth of Discharge(DOD)and C-rate.Second,a thermal-storage cooperative control method based on series compensation is developed to improve the system’s frequency regulation performance.Third,targeting system regulation loss cost and regulation output,and considering constraints on output overshoot and system parameters,an improved Particle Swarm Optimization(PSO)algorithm is employed to tune the parameters of the low-pass filter and the series compensator,thereby reducing regulation losses while enhancing performance.Finally,simulation results demonstrate that the total loss cost of the proposed control strategy is comparable to that of a system with only thermal power participation.However,the thermal power loss cost is reduced by 42.16%compared to the thermal-only case,while simultaneously improving system frequency stability.Thus,the proposed strategy effectively balances system frequency stability and economic efficiency. 展开更多
关键词 Frequency regulation losses of thermal power units energy storage frequency regulation losses series compensation enhanced particle swarm optimization algorithm primary frequency regulation
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Terabit nonlinear frequency division multiplexing transmission desensitized to laser frequency offset and phase noise 认领 引用
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作者 Xiang Cai Xiansong Fang +4 位作者 Jiayu Zheng Yixiao Zhu Xinyu Chen Xian Zhou Fan Zhang 《Advanced Photonics Nexus》 CSCD 2026年第2期90-99,共10页
Nonlinear frequency division multiplexing(NFDM)utilizes the nonlinear Fourier transform(NFT)to decompose signals into the nonlinear frequency domain that inherently resists fiber Kerr nonlinearity distortions.However,... Nonlinear frequency division multiplexing(NFDM)utilizes the nonlinear Fourier transform(NFT)to decompose signals into the nonlinear frequency domain that inherently resists fiber Kerr nonlinearity distortions.However,practical NFDM has been hindered by sensitivity to laser frequency offset and phase noise.In conventional NFDM receivers,a residual frequency offset typically remains before the NFT,whereas phase recovery performed after the NFT can only estimate the average phase rotation per burst,fundamentally limiting tolerance to frequency-phase impairments.In this work,we propose and experimentally demonstrate a residual carrier scheme to compensate for frequency offset and phase noise before the receiver NFT with sampling-point-level precision.Using a 3 MHz distributed feedback(DFB)laser,this scheme enables 1.0 Tb∕s PS-256 QAM NFDM transmission over 320 km,with a high spectral efficiency of 9.85 b∕s∕Hz.The Q2-factor degradation is only 0.85 dB as the total linewidth increases from 200 Hz to 3.1 MHz.The scheme achieves a Q2-factor improvement of 2.6 dB with 100 k Hz external cavity lasers and>6 dB with a 3 MHz DFB laser,compared with the conventional time-domain pilot method.To our knowledge,this is the first time NFDM demonstrates comparable tolerance to frequency-phase impairments as single-carrier systems.The proposed scheme desensitizes NFDM to frequency-phase impairments,overcoming a major barrier to practical deployment. 展开更多
关键词 nonlinear frequency division multiplexing nonlinear Fourier transform frequency offset phase noise residual carrier
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Dominant frequency response and dynamic mechanism of rock slopes under blasting loads:A machine learning-driven time-frequency analysis 认领 引用
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作者 MA Ke PENG Yilin +2 位作者 LIAO Zhiyi LUO Longlong HUANG Yinglu 《Journal of Mountain Science》 SCIE CSCD 2026年第3期1334-1354,共21页
Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability.Nevertheless,the spatiotemporal evolution,nonlinear dependence on blasting parameters,and predic... Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability.Nevertheless,the spatiotemporal evolution,nonlinear dependence on blasting parameters,and predictive behavior of dominant frequency responses in slope vibrations remain insufficiently understood and quantified.This study combines time-frequency analysis with machine learning to explore how the dominant frequency(fd)evolves in slopes under blasting.Continuous Wavelet Transform(CWT)was employed to characterize the temporal-frequency evolution of vibration signals,revealing that the dominant frequency exhibits strong spatial dependence and nonlinear variability influenced by blasting parameters and rock mass structures.Three machine learning models,namely Back Propagation Neural Network(BP),Support Vector Machine(SVM),and Random Forest(RF),were developed to predict fd based on 1,000 monitoring samples obtained from numerical and field simulations.Among them,the RF model achieved the highest prediction accuracy,with mean absolute percentage errors(MAPE)below 15%,demonstrating strong robustness and generalization capability.Our analysis shows that external excitation factors,especially the loading frequency(fd),mainly control the frequency response,while internal controlling factors,such as spatial position,lithological variation,and mechanical heterogeneity,modulate localized frequency amplification and energy redistribution.The results reveal that fd tends to decrease with elevation and distance from the blasting source,whereas structural planes and weathered zones induce high-frequency amplification due to scattering and modal coupling effects.This study offers a new framework combining time-frequency analysis and machine learning to measure the nonlinear interaction between blasting and rock mass response,offering new insights for dynamic stability evaluation and hazard mitigation in complex rock slope systems. 展开更多
关键词 Blasting vibration Time-frequency domain analysis Machine learning Dominant frequency
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Robust connectivity in time-frequency dual fading channels for the 6G satellite IoT:chirp and FRFT 认领 引用
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作者 Wenliang Lin Xinghao Cao +6 位作者 Ke Wang Zhongliang Deng Yishan He Kejia Cui Yaohua Deng Da Wan Zhiwei He 《Digital Communications and Networks》 SCIE EI CSCD 2026年第2期375-387,共13页
With the development of Sixth-Generation(6G)mobile communication technologies,Low Earth Orbit(LEO)satellite communication systems have become extremely important in mobile communications owing to their large coverage,... With the development of Sixth-Generation(6G)mobile communication technologies,Low Earth Orbit(LEO)satellite communication systems have become extremely important in mobile communications owing to their large coverage,high efficiency,and low cost.However,the high dynamic LEO satellite channels cause serious time-frequency dual selective fading,significantly impairing the performance of conventional single time or frequency domain synchronization algorithms and limiting their applicability.To address these challenges,this paper proposes a synchronization algorithm based on Linear Frequency Modulation(LFM)signals and the Fractional Fourier Transform(FRFT).Exploiting the inherent robustness of LFM signals against frequency deviations and multipath effects,coupled with their energy concentration property in the optimal fractional Fourier domain,the proposed algorithm enables efficient synchronization with enhanced resilience to time-frequency variations.Furthermore,LFM preamble sequences are optimally designed for diverse channel conditions.This work presents a theoretical analysis of the time-frequency nonstationary characteristics of LEO satellite channels and discusses the performance limitations of traditional synchronization algorithms.The proposed integrated FRFTLFM synchronization framework and sequence optimization scheme are rigorously evaluated via comprehensive simulations.The results demonstrate substantial improvements in synchronization accuracy and computational efficiency compared with conventional methods,particularly under time-frequency dual selective fading LEO satellite channels.The algorithm provides a robust and reliable solution for time-frequency synchronization in LEO satellite communication systems,thereby enhancing overall system performance and reliability. 展开更多
关键词 Time-frequency synchronization Linear frequency modulation Fractional fourier transform Low earth orbit satellite communications Nonstationary channel
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Simultaneous frequency stabilization of two 1550-nm lasers at single-photon level 认领 引用
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作者 Bo Yu Zhenqiang Yin +2 位作者 Weijie Ding Hui Yang Weixin Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第4期453-458,共6页
The twin-field quantum key distribution(TF-QKD)requires that two lasers hundreds of kilometers apart must have the same frequency to achieve the high single-photon interference visibility.This means that both lasers n... The twin-field quantum key distribution(TF-QKD)requires that two lasers hundreds of kilometers apart must have the same frequency to achieve the high single-photon interference visibility.This means that both lasers need to be stabilized to the same frequency reference.A simple and robust system is presented for simultaneously stabilizing two 1550-nm lasers at the single-photon level.By utilizing the single-photon multi-frequency modulation technology,both the fiber laser and distributed feedback(DFB)laser are stabilized to theπ-phase shifted fiber Bragg grating at the same time.The frequency fluctuations of fiber laser and DFB laser are bounded within 1.39 MHz and 1.53 MHz over 2000 s,respectively.These two frequency-stabilized 1550-nm lasers could be used for TF-QKD. 展开更多
关键词 single-photon multi-frequency modulation frequency stabilization π-phase shifted fiber Bragg grating
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Magnetic-Dielectric Synergy in One-Dimensional Metal Heterostructures for Enhanced Low-Frequency Microwave Absorption 认领 引用 被引量：3
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作者 Feiyue Hu Peigen Zhang +10 位作者 Pei Ding Shuo Zhang Bingbing Fan Ali Saffar Shamshirgar Wei Zheng Wenwen Sun Longzhu Cai Haijiao Xie Qiyue Shao Johanna Rosen ZhengMing Sun 《Nano-Micro Letters》 SCIE EI CAS CSCD 2026年第5期371-390,共20页
Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promisin... Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promising strategy to address this issue.To realize the synergy,herein,Sn whiskers with an in situ oxide layer served as substrates for magnetic-loss-active CoNi nanosheet growth,forming a hierarchical CoNi@SnO2@Sn(CNS)heterostructure.The CNS absorber achieves a minimum reflection loss(RLmin)value of-62.29 dB with an effective absorption bandwidth(EAB)of 2.2 GHz,covering the entire C-band with 70%absorption at only 2.61 mm thickness.The nanosheet design of CoNi enhances magnetic anisotropy to promote natural resonance,while the conductive Sn core and abundant Sn/SnO2 and CoNi/SnO2 heterointerfaces facilitate conduction loss and dielectric polarization.When composited into a thermoplastic polyurethane(TPU)matrix,the resulting CNS/TPU-2 film(20 wt%CNS)exhibits an RLmin value of-61.04 dB and a 2.5 GHz EAB.Its in-plane and through-plane thermal conductivities reach 2.41 and 0.51 W m-1 K-1,representing 4.1 and 2.6 times those of pure TPU films,respectively,facilitating heat dissipation from protected devices.This work provides valuable insights into magnetic-dielectric synergy for low-frequency MA of 1D metal-based materials,offering promising potential for 5G communications and flexible electronics. 展开更多
关键词 Low frequency microwave absorption Magnetic-dielectric synergy MAX phase CoNi@SnO2@Sn heterostructure Thermal conductivity
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Effect of dynamic disturbance frequency on brittle failure of granite in deep excavation 认领 引用 被引量：2
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作者 Ben-Guo He Hanyi Liu +1 位作者 Xia-Ting Feng Hongyuan Fu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第2期1002-1015,共14页
Dynamic disturbances with various frequencies could trigger different failure modes of deep excavations.Superimposed on this static stress are dynamic disturbances due to various dynamic vibrations,e.g.excavation blas... Dynamic disturbances with various frequencies could trigger different failure modes of deep excavations.Superimposed on this static stress are dynamic disturbances due to various dynamic vibrations,e.g.excavation blasting,blasting,tunnel boring machine(TBM)vibration,rockburst wave,earthquakes.Specifically,these dynamic sources are characterized by a wide range of wave frequencies f,resulting in differences in failure modes.A series of true-triaxial compression tests were conducted on granite to simulate the excavation-induced stress path in three-dimensional(3D)stresses.Subsequently,a dynamic disturbance with various frequencies was applied to a cuboid specimen,to reveal the behavior associated with brittle failure.The dynamic disturbance with frequencies f of 5 Hz,10 Hz,and 40 Hz generates less disturbed energy components in the granite together with higher peak strength.However,dynamic disturbances with f of 20 Hz and 30 Hz resulted in a lower peak strength;the peak strength of the rock increases sp albeit it decreases at first,then increases.This U-shaped phenomenon relates to the natural frequency of the granite under such stress conditions.Different rock lithologies consisting of diverse mineral composition,respond differently to each sensitive resonance frequency.Interestingly,the weak disturbance stress with a high frequency f and low amplitude A increases the ratio of crack damage to peak strength(scd/sp)in the granite.This leads to the inhibition of the expansion of the granite during the dynamic disturbance process.Multiple penetrating tensileeshear cracks appear in the s3-direction as the disturbance frequency f increases. 展开更多
关键词 True-triaxial compression Disturbance frequency Brittle failure Characteristic strength Deep excavation
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Effects of Temperature,Loading Frequency,Stress Amplitude,and Stress Ratio on the Low-Cycle Fatigue Behavior of FeMnSiCrNi Shape Memory Alloys 认领 引用 被引量：1
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作者 Bo Xu Beihai Huang +4 位作者 Sen Tang Xiang Xu Huabei Peng Chong Wang Qingyuan Wang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2026年第2期133-151,共19页
FeMnSi-based shape memory alloys(SMAs)have great applied potential to large-scale structures in civil engineering,especially as an aseismic structural material.Low-cycle fatigue performance is one of the most importan... FeMnSi-based shape memory alloys(SMAs)have great applied potential to large-scale structures in civil engineering,especially as an aseismic structural material.Low-cycle fatigue performance is one of the most important properties of FeMnSi-based SMA aseismic materials.However,the low-cycle fatigue behavior of such SMAs,especially the stress-controlled low-cycle fatigue behavior(with ratchetting effect),has not been clearly understood.In this work,the low-cycle fatigue behavior of the FeMnSiCrNi SMAs subjected to stress-controlled cyclic tension–compression loads is investigated,and the effects of temperature,loading frequency,stress amplitude,and stress ratio are addressed.By analyzing the cyclic stress–strain response,fatigue fracture surface morphology,dissipation energy,ratchetting strain,and equivalent damping ratio,the mechanisms behind the temperature-,loading frequency-,stress amplitude-,and stress ratio-dependent low-cycle fatigue behavior are discussed.The results show that the plasticity,martensitic transformation,and/or the ratchetting strain caused by their tension–compression asymmetry are the decisive factors affecting the low-cycle fatigue behavior of FeMnSiCrNi SMAs. 展开更多
关键词 FeMnSiCrNi shape memory alloy Low-cycle fatigue behavior Temperature Loading frequency Stress amplitude Stress ratio
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Optimization of the frequency offset increment of FDA-MIMO based on cuckoo search algorithm 认领 引用 被引量：1
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作者 WANG Bo ZHAO Yu +2 位作者 LI Yonglin YANG Rennong XUE Junjie 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2026年第1期157-170,共14页
Frequency diverse array multiple-input multiple-output(FDA-MIMO)radar has gained considerable research attention due to its ability to effectively counter active repeater deception jamming in complex electromagnetic e... Frequency diverse array multiple-input multiple-output(FDA-MIMO)radar has gained considerable research attention due to its ability to effectively counter active repeater deception jamming in complex electromagnetic environments.The effectiveness of interference suppression by FDA-MIMO is limited by the inherent range-angle coupling issue in the FDA beampattern.Existing literature primarily focuses on control methods for FDA-MIMO radar beam direction under the assumption of static beampatterns,with insufficient exploration of techniques for managing nonstationary beam directions.To address this gap,this paper initially introduces the FDA-MIMO signal model and the calculation formula for the FDA-MIMO array output using the minimum variance distortionless response(MVDR)beamformer.Building on this,the problem of determining the optimal frequency offset for the FDA is rephrased as a convex optimization problem,which is then resolved using the cuckoo search(CS)algorithm.Simulations confirm the effectiveness of the proposed approach,showing that the frequency offsets obtained through the CS algorithm can create a dot-shaped beam direction at the target location while effectively suppressing interference signals within the mainlobe. 展开更多
关键词 frequency diverse array multiple-input multiple-output(FDA-MIMO) convex optimization cuckoo search algorithm beampattern
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Long-Term Bridge Health Evaluation Using Resonant Frequency Changes under Random Loading Conditions 认领 引用
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作者 Thi Kim Chi Duong Bich-Ngoc.Mach +2 位作者 Hoa-Cuc.Nguyen Thi Nhu Quynh Trinh Thanh Q.Nguyen 《Structural Durability & Health Monitoring》 EI 2026年第1期86-120,共35页
This study explores theoretical insights and experimental results on monitoring load-carrying capacity degradation in bridge spans through frequency analysis.Experiments were conducted on real bridge structures,includ... This study explores theoretical insights and experimental results on monitoring load-carrying capacity degradation in bridge spans through frequency analysis.Experiments were conducted on real bridge structures,including the Binh Thuan Bridge,focusing on analyzing the power spectral density(PSD)of vibration signals under random traffic loads.Detailed digital models of various bridge spans with different structural designs and construction periods were developed to ensure diversity.The study utilized PSD to analyze the vibration signals from the bridge spans under various loading conditions,identifying the vibration frequencies and the corresponding response regions.The research correlated the observed frequency changes of PSD with the actual deterioration of the bridges over time,identifying patterns that indicate a reduction in stiffness.Experiments demonstrated that frequency changes,particularly in high-frequency regions,are directly related to a reduction in the stiffness of bridge spans.This supports the hypothesis that natural frequencies can serve as effective indicators of structural damage.Furthermore,the emergence and shift of resonant frequency regions provide valuable insights into the extent of damage in actual bridge spans,highlighting the potential for using changes in resonant frequency regions as a new tool for structural damage detection. 展开更多
关键词 Frequency power spectral density vibration signals vibration frequencies resonant frequency regions structural damage detection
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Coordinated Control Strategy for Active Frequency Support in PV-Storage Integrated Systems 认领 引用
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作者 Junxian Ma Haonan Zhao +3 位作者 Zhibing Hu Yaru Shen Fan Ding Shouqi Jiang 《Energy Engineering》 EI 2026年第2期134-152,共19页
Energy storage-equipped photovoltaic(PV-storage)systems can meet frequency regulation requirements under various operating conditions,and their coordinated support for grid frequency has become a future trend.To addre... Energy storage-equipped photovoltaic(PV-storage)systems can meet frequency regulation requirements under various operating conditions,and their coordinated support for grid frequency has become a future trend.To address frequency stability issues caused by low inertia and weak damping,this paper proposes a multi-timescale frequency regulation coordinated control strategy for PV-storage integrated systems.First,a self-synchronizing control strategy for grid-connected inverters is designed based on DC voltage dynamics,enabling active inertia support while transmitting frequency variation information.Next,an energy storage inertia support control strategy is developed to enhance the frequency nadir,and an active frequency support control strategy for PV system considering a frequency regulation deadband is proposed,where the deadband value is determined based on the power regulation margin of synchronous generators,allowing the PV-storage system to adaptively switch between inertia support and primary frequency regulation under different disturbance conditions.This approach ensures system frequency stability while fully leveraging the regulation capabilities of heterogeneous resources.Finally,the real-time digital simulation results of the PV-storage integrated system demonstrate that,compared to existing control methods,the proposed strategy effectively reduces the rate of change of frequency and improves the frequency nadir under various disturbance scenarios,verifying its effectiveness. 展开更多
关键词 PV-storage integrated systems inertia self-synchronization control primary frequency regulation frequency stability
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Monolithic Single-Frequency Laser on Thin-Film Lithium Niobate Platform by the Vernier Effect 认领 引用
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作者 Chao Sun Zhao-Xiang Liu +2 位作者 Jin-Ming Chen Min Wang Ya Cheng 《Chinese Physics Letters》 SCIE EI CAS CSCD 2026年第2期111-116,共6页
We present a monolithic single-frequency microring laser utilizing Er3+-doped thin film lithium niobate(TFLN)on insulator.The device is fabricated employing a dual-cavity architecture,in which two microring resonat... We present a monolithic single-frequency microring laser utilizing Er3+-doped thin film lithium niobate(TFLN)on insulator.The device is fabricated employing a dual-cavity architecture,in which two microring resonators are nested through two pulley coupling regions and share a common semicircular cavity.The singlefrequency laser achieves a peak output power of 146μW,with a side mode suppression ratio of 32 dB and slope efficiency of 0.7%,operating at a wavelength of 1530.85 nm,which leverages gain competition and the Vernier effect.Furthermore,the single-frequency laser emission can be selectively switched between 1530.85 nm and 1547.13 nm by a precise adjustment of the device's structural parameters.Our research establishes the foundation for a fully integrated multifunction TFLN system,which exhibits great potential applications in advancing optical computation,bio-chemical sensing,and signal processing. 展开更多
关键词 single frequency laser monolithic laser singlefrequency laser gain competiti microring resonators thin film lithium niobate semicircular cavitythe thin film lithium niobate tfln
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Development of a piezoresistive accelerometer with both high natural frequency and superior overload capability 认领 引用
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作者 Yong Xia Xinyao Meng +8 位作者 Yang Lv Xiangguang Han Zhixia Qiao Mingzhi Yu Chen Jia Qing Zhang Ping Yang Dejiang Lu Libo Zhao 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2026年第7期186-197,共12页
Accelerometers featuring high natural frequencies and superior overload capabilities are particularly valuable in applications such as military low-threshold-weapon fuzes.However,synergistic improve-ment of these para... Accelerometers featuring high natural frequencies and superior overload capabilities are particularly valuable in applications such as military low-threshold-weapon fuzes.However,synergistic improve-ment of these parameters is bottlenecked by the trade-off between sensitivity and natural frequency,and the trade-off between natural frequency and displacement limit.Here,via designing anti-overload structures integrated with the pure-axial-stressed sensing structure,we achieve simultaneous high natural frequency and superior overload capability.The proposed sensor is fabricated and characterized.Results yield a sensitivity of 0.037±0.002 mV/g at 2 V and a natural frequency of 31.35±0.72 kHz,comparable to the reference sensor,and an overload capability of 19445.80±290.55 g representing a 133.84%improvement.Accelerometers with high natural frequency and superior overload capability enable high-fidelity measurement of broadband signals under harsh environments. 展开更多
关键词 Piezoresistive accelerometer Anti-overload structures Pure-axial-stressed sensing structure Natural frequency Overload capability
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Broadband low-frequency sound absorption via a cross-bridged hex acoustic metamaterial with extended necks 认领 引用
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作者 YAN Hong-yu XIE Su-chao +2 位作者 WANG Kui ZHANG Feng-yi JING Kun-kun 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第2期987-996,共10页
To simultaneously address low to mid frequency noise absorption and stringent thickness constraints,a novel cross-bridged hex structure with embedded necks was developed from conventional honeycombs.The acoustic perfo... To simultaneously address low to mid frequency noise absorption and stringent thickness constraints,a novel cross-bridged hex structure with embedded necks was developed from conventional honeycombs.The acoustic performance of these metamaterials was systematically investigated via theoretical analysis,experimental verification,and numerical simulation.Results demonstrate that an exponential 2 penalty factor objective achieves superior uniformity of sound absorption within 500−1000 Hz band,surpassing both average-driven and multi-level reward methods.Among the four tested optimization algorithms,a hybrid CMAES+LBFGS scheme reduced the final penalty by up to 98%,highlighting its capacity for effectively navigating the complex design space of cross-bridged structures. 展开更多
关键词 cross-bridged hex acoustic metamaterial mid-low frequency CMAES-LBFGS sound absorption performance
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Buckling and parametric excitation stability optimization of fluid-conveying pipes by frequency design 认领 引用
19
作者 Xiaoye MAO Kexin CHANG +3 位作者 Jie JING Tianchang DENG Hu DING Liqun CHEN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2026年第4期675-694,共20页
A methodology is proposed to enhance the buckling and parametric excitation stability of fluid-conveying pipes by designing their natural frequencies.As a direct indicator of structural stiffness with respect to defor... A methodology is proposed to enhance the buckling and parametric excitation stability of fluid-conveying pipes by designing their natural frequencies.As a direct indicator of structural stiffness with respect to deformation,which is intrinsically related to the overall structural stability,the natural frequency is adopted as the primary design criterion for enhancing system stability.Based on the generalized Hamilton's principle,the governing equation for a multi-restrained pipe system is derived.The analysis reveals that,the natural frequencies can be maximized by appropriately selecting the constraint locations,which induces the best buckling stability.Although increasing the flow velocity generally reduces the natural frequency,the optimal constraint location remains relatively unchanged,eventually approaching the location of the maximal critical flow speed,beyond which the pipe loses its static stability.Furthermore,the proposed method introduces additional nodes into the natural mode shape,indicating that a higher energy threshold is required to trigger the resonance.Consequently,the parametric resonance under pulsating flow conditions becomes more difficult to initiate.Meanwhile,with the frequency design,the pipe can prevent the occurrence of parametric resonance with smaller critical damping.Compared with other approaches aimed at enhancing the stability of fluid-conveying pipe systems,the proposed method offers greater practicality for engineering applications,as it only requires adjusting the constraint locations and the optimal location is insensitive to the flow speed. 展开更多
关键词 fluid-conveying pipe frequency design static bifurcation stability of parametric resonance optimal stability
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Bias compensation for MEMS gyroscopes using Gaussian process regression with resonant frequency and quadrature output 认领 引用
20
作者 Xin Zeng Sujie Xian +3 位作者 Tong Zhou Zhuolin Yu Kun Liu Zhilin Wu 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2026年第4期344-356,共13页
The bias of micro-electro-mechanical system(MEMS)gyroscopes is sensitive to temperature variations,which limits their accuracy in complex thermal environments.To address this issue,this paper proposes a Gaussian proce... The bias of micro-electro-mechanical system(MEMS)gyroscopes is sensitive to temperature variations,which limits their accuracy in complex thermal environments.To address this issue,this paper proposes a Gaussian process regression(GPR)model that uses resonant frequency and quadrature output as inputs to predict and compensate for the full-temperature bias of MEMS gyroscopes in real-time.Without relying on external sensors,the resonant frequency and quadrature output serve as virtual sensors that directly reflect bias variations.To suppress noise and improve modeling accuracy,the bias is preprocessed using particle swarm optimization-optimized variational mode decomposition before training.In addition,a fast computation strategy is developed to improve the computational efficiency of the GPR model.Experimental results demonstrate the effectiveness and superiority of the proposed method.In three repeated trials,the bias instability of the compensated bias is reduced by 46.18%,60.18%,and 63.68%,respectively,compared to the uncompensated bias. 展开更多
关键词 MEMS gyroscope Bias compensation Gaussian process regression Resonant frequency Quadrature output
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