The rapid identification of γ-emitting radionuclides with low activity levels in public areas is crucial for nuclear safety.However,classical methods rely on full-energy peaks in the integral spectrum,requiring suffi...The rapid identification of γ-emitting radionuclides with low activity levels in public areas is crucial for nuclear safety.However,classical methods rely on full-energy peaks in the integral spectrum,requiring sufficient count accumulation for evaluation,thereby limiting response time.The sequential Bayesian approach,which utilizes prior information and considers both photon energies and interarrival times,can significantly enhance the performance of radionuclides identification.This study proposes a theoretical optimization method for the traditional sequential Bayesian approach.Each photon is processed sequentially,and the corresponding posterior probability is updated in real time using a noninformative prior from the Bayesian theory.By comparing the posterior probabilities of the background and radionuclides based on the energy variance and time interval,the type of γ-rays can be identified(background characteristic γ-rays,Compton plateaus γ-rays,or radionuclide-specific characteristic γ-rays).By integrating the information from these multiple characteristic γ-rays,the presence and type of radionuclides were determined based on the final decision function and a set threshold.Based on theoretical research,verification experiments were conducted using a LaBr_(3)(Ce)detector in both low-and natural background radiation environments with typical radionuclides(^(137)Cs,^(60)Co,and ^(133)Ba).The results show that this approach can identify ^(137)Cs in 7.9 s and 8.5 s(source dose rate contribution:approximately 6.5×10^(−3)μGy/h),^(60)Co in 8.1 s and 9.8 s(approximately 4.8×10^(−2)μGy/h),and ^(133)Ba in 4.05 s and 5.99 s(approximately 3.4×10^(−2)μGy/h)under low and natural background radiation,respectively,with a miss rate below 0.01%.This demonstrates the effectiveness of the proposed approach for fast radionuclides identification,even at low activity levels and highlights its potential for enhancing public safety in diverse radiation environments.展开更多
针对现有卫星通信中幅度相位键控(Amplitude Phase Shift Keying,APSK)调制方案依赖商用芯片或FPGA实现、且性能评估多局限于理想高斯信道的问题,提出基于开源软件定义无线电(Software Defined Radio,SDR)平台的动态可重构验证框架。以...针对现有卫星通信中幅度相位键控(Amplitude Phase Shift Keying,APSK)调制方案依赖商用芯片或FPGA实现、且性能评估多局限于理想高斯信道的问题,提出基于开源软件定义无线电(Software Defined Radio,SDR)平台的动态可重构验证框架。以数字视频广播卫星第二代(Digital Video Broadcasting-Satellite Second Generation,DVB-S2)标准为基准,在GNU Radio平台构建高阶调制-卫星信道联合仿真系统,支持16APSK与32APSK调制解调链路的灵活配置,深度集成Loo与Corazza模型以精确模拟多径时延、阴影衰落及多普勒频移特性。通过HackRF SDR硬件平台实现基带生成、射频收发至接收解调的端到端硬件在环验证。该框架可为6G天地一体化网络中高阶调制的频谱效率、抗衰落性能及功放非线性适应性研究提供可扩展实验平台。展开更多
This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the traini...This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the training dataset,and one solution is applied to improve the distribution of the training data by augmenting minority class samples using a deep convolutional generative adversarial network.Experi.mental results demonstrate that retraining the deep learning model with the newly generated dataset leads to a new fast radio burst classifier,which effectively reduces false positives caused by periodic wide-band impulsive radio frequency interference,thereby enhancing the performance of the search pipeline.展开更多
The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very lon...The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.展开更多
The random distribution of one-dimensional nanofillers in composite polymer electrolytes(CPEs) typically results in tortuous ion transport pathways,severely limiting ionic conductivity and Li^(+) flux uniformity.Herei...The random distribution of one-dimensional nanofillers in composite polymer electrolytes(CPEs) typically results in tortuous ion transport pathways,severely limiting ionic conductivity and Li^(+) flux uniformity.Herein,an innovative electric field-assisted strategy is proposed to construct vertically aligned ion channels in CPEs using lithiated halloysite nano tubes(HNTs-SO_(3)Li)embedded within a polyurethane acrylate/polyethylene glycol diacrylate(PUA/PEGDA) matrix.Under an alternating electric field,the nanotubes orient perpendicularly,forming continuous,low-tortuosity pathways that significantly enhance roomtemperature ionic conductivity.The aligned structure not only shortens Li+transport distances but also homogenizes ion flux at the electrode interface,effectively suppressing lithium dendrite growth.Electrochemical characterization reveals exceptional stability.Three-dimensional structural reconstruction and ion transport simulations further demonstrate that the ordered channels promote uniform Li+distribution and faster ion kinetics compared to disordered systems.This study provides a scalable and efficient approach to designing high-performance CPEs for next-generation solid-state batteries,addressing critical challenges in ionic conductivity,interfacial stability,and dendrite suppression.展开更多
In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essent...In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essential for accurate atmospheric water content estimation.However,global models often overlook regional climatic variability,leading to reduced accuracy in localized applications.This study introduces an improved T_(m)model developed using radiosonde observations across Iran and GNSS radio occultation(RO)profiles from CHAMP,GRACE,MetOp-A/B/C,COSMIC,TerraSAR-X,and TanDEM-X missions collected between 2007 and 2022.A novel integral formulation was proposed to estimate T_(m)more accurately by incorporating vertical water vapor distribution and temperature linearity.Based on this formulation,three regional T_(m)models were constructed using annual,semiannual,and diurnal periodicities,along with surface temperature(T_(s)),each varying in structure and complexity.Validation against independent radiosonde observations from 2022 showed that Models Two and Three outperformed the Bevis model,reducing RMSE by 30.7%.When evaluated against GNSS RO profiles,Model One—excluding T_(s)due to its inaccessibility in RO data—yielded the highest accuracy,with a 42.6%improvement in RMSE over the Bevis model.To evaluate the practical effectiveness of the proposed T_(m)model,PWV was derived from GNSS data at the tehn and tabz stations during the second half of 2022and compared with PWV values obtained from co-located radiosonde observations in Tehran and Tabriz.Using T_(m)from Model One improved PWV estimation compared to the Bevis model,reducing RMSE and MAE by up to 54%and 53.8%in Tabriz and 50.6%and 52.9%in Tehran,respectively.These results demonstrate that regionalized T_(m)modeling,particularly approaches that avoid dependence on T_(s),can significantly enhance GNSS-based PWV estimation in areas with limited surface data.展开更多
3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensur...3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.展开更多
Orthogonal Frequency Division Multiplexing(OFDM)enables efficient Dynamic Spectrum Access(DSA)but suffers from high sidelobe that causes excessive out-of-band(OOB)emissions and expose the system to spectrum-layer cybe...Orthogonal Frequency Division Multiplexing(OFDM)enables efficient Dynamic Spectrum Access(DSA)but suffers from high sidelobe that causes excessive out-of-band(OOB)emissions and expose the system to spectrum-layer cyberattacks such as man-in-the-middle(MITM),eavesdropping,and primary user emulation(PUE)attacks.To address both spectral leakage and its security implications,this paper introduces a secure and intelligent hybrid optimization strategy that combinesan Eigenspace-based Generalized Sidelobe Canceller(ES-GSC)with a Genetic Algorithm(GA),to derive optimally weighted cancellation carriers.The proposed method jointly suppresses sidelobes and reinforces resistance to leakage-based attacks.MATLAB Simulation demonstrate considerable reductions in OOB emissions and higher resilience against spectrum-layer threats compared with existing techniques.展开更多
Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evoluti...Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evolution and capacity contributions of a series of LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)cathodes under XFC conditions.All NCM cathodes(NCM-92,NCM-83,and NCM-622)deliver -60%of their capacities with less than 2%unit cell volume expansion during the H1-H2 phase transition,but the subsequent H2-H3 phase transition exhibits significant compositional and rate dependence.The NCM-92 cathode shows a maximum d-spacing shrinkage of-5.3%at 6 C,which is larger than that of NCM-83(-4.1%)and NCM-622(-0.05%).Furthermore,NCM-92 follows a“phase heterogeneity”pathway for its structural evolution above 4.2 V,distinct from the“solid-solution”pathway observed in NCM-83 and NCM-622.This phase heterogeneity is evidenced by the splitting of the(003)diffraction peak and a decrease in intensity during the H2-H3 phase transition,indicating the formation of lithium-rich/depleted domains.These findings establish a direct correlation between cathode composition,structural dynamics,and XFC performance,highlighting a critical trade-off between structural stability and fast-charging capability in nickel-rich layered oxides.展开更多
In this paper,a fast step heterodyne light-induced thermoelastic spectroscopy(SH-LITES)sensor using a high-frequency quartz tuning fork(QTF)with resonant frequency of~100 kHz is reported for the first time.The theoret...In this paper,a fast step heterodyne light-induced thermoelastic spectroscopy(SH-LITES)sensor using a high-frequency quartz tuning fork(QTF)with resonant frequency of~100 kHz is reported for the first time.The theoretical principle of heterodyne LITES(H-LITES)signal generation is analyzed firstly,and an acetylene(C_(2)H_(2))H-LITES sensor is established to verify its performance.Experimental comparisons between the high-frequency QTF and a standard commercial QTF with resonant frequency of~32.768 kHz reveal that the high-frequency QTF exhibits a tenfold faster response time.Specifically,the H-LITES sensor with this QTF achieves a 33 ms measurement cycle,90%shorter than commercial counterparts.Furthermore,The SH-LITES technique is proposed to further shorten the scanning time to 15 ms,which achieves the shortest LITES measurement time known to date.To demonstrate its advantages in dynamic gas detection,an H_(2)O-LITES system integrating both QTF types is constructed for real-time monitoring of H_(2)O concentration during different respiration patterns.Comparative measurements show that the SH-LITES more accurately captures dynamic H_(2)O concentration fluctuations during respiration,outperforming the commercial QTF-based H-LITES sensor in rapid response scenarios.展开更多
基金supported by the Program for NIM-Basic Research Business Expenses Key Field Program,China(No.AKYCX2315).
文摘The rapid identification of γ-emitting radionuclides with low activity levels in public areas is crucial for nuclear safety.However,classical methods rely on full-energy peaks in the integral spectrum,requiring sufficient count accumulation for evaluation,thereby limiting response time.The sequential Bayesian approach,which utilizes prior information and considers both photon energies and interarrival times,can significantly enhance the performance of radionuclides identification.This study proposes a theoretical optimization method for the traditional sequential Bayesian approach.Each photon is processed sequentially,and the corresponding posterior probability is updated in real time using a noninformative prior from the Bayesian theory.By comparing the posterior probabilities of the background and radionuclides based on the energy variance and time interval,the type of γ-rays can be identified(background characteristic γ-rays,Compton plateaus γ-rays,or radionuclide-specific characteristic γ-rays).By integrating the information from these multiple characteristic γ-rays,the presence and type of radionuclides were determined based on the final decision function and a set threshold.Based on theoretical research,verification experiments were conducted using a LaBr_(3)(Ce)detector in both low-and natural background radiation environments with typical radionuclides(^(137)Cs,^(60)Co,and ^(133)Ba).The results show that this approach can identify ^(137)Cs in 7.9 s and 8.5 s(source dose rate contribution:approximately 6.5×10^(−3)μGy/h),^(60)Co in 8.1 s and 9.8 s(approximately 4.8×10^(−2)μGy/h),and ^(133)Ba in 4.05 s and 5.99 s(approximately 3.4×10^(−2)μGy/h)under low and natural background radiation,respectively,with a miss rate below 0.01%.This demonstrates the effectiveness of the proposed approach for fast radionuclides identification,even at low activity levels and highlights its potential for enhancing public safety in diverse radiation environments.
文摘针对现有卫星通信中幅度相位键控(Amplitude Phase Shift Keying,APSK)调制方案依赖商用芯片或FPGA实现、且性能评估多局限于理想高斯信道的问题,提出基于开源软件定义无线电(Software Defined Radio,SDR)平台的动态可重构验证框架。以数字视频广播卫星第二代(Digital Video Broadcasting-Satellite Second Generation,DVB-S2)标准为基准,在GNU Radio平台构建高阶调制-卫星信道联合仿真系统,支持16APSK与32APSK调制解调链路的灵活配置,深度集成Loo与Corazza模型以精确模拟多径时延、阴影衰落及多普勒频移特性。通过HackRF SDR硬件平台实现基带生成、射频收发至接收解调的端到端硬件在环验证。该框架可为6G天地一体化网络中高阶调制的频谱效率、抗衰落性能及功放非线性适应性研究提供可扩展实验平台。
基金supported by the Chinese Academy of Science"Light of West China"Program(2022-XBQNXZ-015)the National Natural Science Foundation of China(11903071)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China and administered by the Chinese Academy of Sciences。
文摘This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the training dataset,and one solution is applied to improve the distribution of the training data by augmenting minority class samples using a deep convolutional generative adversarial network.Experi.mental results demonstrate that retraining the deep learning model with the newly generated dataset leads to a new fast radio burst classifier,which effectively reduces false positives caused by periodic wide-band impulsive radio frequency interference,thereby enhancing the performance of the search pipeline.
基金supported by the National Science and Technology Major Project(E152KJ1201)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0036)+1 种基金the National Natural Science Foundation of China(42030105 and 11973046)the National SKA Program of China(2020SKA0120200).
文摘The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.
基金the Program of National Key Research and Development of China (No.2022YFB3603702, No. 2023YFC3905301)Hubei Provincial Natural Science Foundation of China (No. 2025AFA025)the Research Fund of Jianghan University (No. 2023KJZX01)。
文摘The random distribution of one-dimensional nanofillers in composite polymer electrolytes(CPEs) typically results in tortuous ion transport pathways,severely limiting ionic conductivity and Li^(+) flux uniformity.Herein,an innovative electric field-assisted strategy is proposed to construct vertically aligned ion channels in CPEs using lithiated halloysite nano tubes(HNTs-SO_(3)Li)embedded within a polyurethane acrylate/polyethylene glycol diacrylate(PUA/PEGDA) matrix.Under an alternating electric field,the nanotubes orient perpendicularly,forming continuous,low-tortuosity pathways that significantly enhance roomtemperature ionic conductivity.The aligned structure not only shortens Li+transport distances but also homogenizes ion flux at the electrode interface,effectively suppressing lithium dendrite growth.Electrochemical characterization reveals exceptional stability.Three-dimensional structural reconstruction and ion transport simulations further demonstrate that the ordered channels promote uniform Li+distribution and faster ion kinetics compared to disordered systems.This study provides a scalable and efficient approach to designing high-performance CPEs for next-generation solid-state batteries,addressing critical challenges in ionic conductivity,interfacial stability,and dendrite suppression.
文摘In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essential for accurate atmospheric water content estimation.However,global models often overlook regional climatic variability,leading to reduced accuracy in localized applications.This study introduces an improved T_(m)model developed using radiosonde observations across Iran and GNSS radio occultation(RO)profiles from CHAMP,GRACE,MetOp-A/B/C,COSMIC,TerraSAR-X,and TanDEM-X missions collected between 2007 and 2022.A novel integral formulation was proposed to estimate T_(m)more accurately by incorporating vertical water vapor distribution and temperature linearity.Based on this formulation,three regional T_(m)models were constructed using annual,semiannual,and diurnal periodicities,along with surface temperature(T_(s)),each varying in structure and complexity.Validation against independent radiosonde observations from 2022 showed that Models Two and Three outperformed the Bevis model,reducing RMSE by 30.7%.When evaluated against GNSS RO profiles,Model One—excluding T_(s)due to its inaccessibility in RO data—yielded the highest accuracy,with a 42.6%improvement in RMSE over the Bevis model.To evaluate the practical effectiveness of the proposed T_(m)model,PWV was derived from GNSS data at the tehn and tabz stations during the second half of 2022and compared with PWV values obtained from co-located radiosonde observations in Tehran and Tabriz.Using T_(m)from Model One improved PWV estimation compared to the Bevis model,reducing RMSE and MAE by up to 54%and 53.8%in Tabriz and 50.6%and 52.9%in Tehran,respectively.These results demonstrate that regionalized T_(m)modeling,particularly approaches that avoid dependence on T_(s),can significantly enhance GNSS-based PWV estimation in areas with limited surface data.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB2807903)the National Natural Science Foundation of China(Grant Nos.62025502 and 62475050)the Guangdong Introducing Innovative and Entrepreneurial Teams of“The Pearl River Talent Recruitment Program”(Grant No.2021ZT09X044)。
文摘3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.
文摘Orthogonal Frequency Division Multiplexing(OFDM)enables efficient Dynamic Spectrum Access(DSA)but suffers from high sidelobe that causes excessive out-of-band(OOB)emissions and expose the system to spectrum-layer cyberattacks such as man-in-the-middle(MITM),eavesdropping,and primary user emulation(PUE)attacks.To address both spectral leakage and its security implications,this paper introduces a secure and intelligent hybrid optimization strategy that combinesan Eigenspace-based Generalized Sidelobe Canceller(ES-GSC)with a Genetic Algorithm(GA),to derive optimally weighted cancellation carriers.The proposed method jointly suppresses sidelobes and reinforces resistance to leakage-based attacks.MATLAB Simulation demonstrate considerable reductions in OOB emissions and higher resilience against spectrum-layer threats compared with existing techniques.
基金financially supported by Fujian Science&Technology Innovation Laboratory for Energy Devices of China(21C LAB)。
文摘Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evolution and capacity contributions of a series of LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)cathodes under XFC conditions.All NCM cathodes(NCM-92,NCM-83,and NCM-622)deliver -60%of their capacities with less than 2%unit cell volume expansion during the H1-H2 phase transition,but the subsequent H2-H3 phase transition exhibits significant compositional and rate dependence.The NCM-92 cathode shows a maximum d-spacing shrinkage of-5.3%at 6 C,which is larger than that of NCM-83(-4.1%)and NCM-622(-0.05%).Furthermore,NCM-92 follows a“phase heterogeneity”pathway for its structural evolution above 4.2 V,distinct from the“solid-solution”pathway observed in NCM-83 and NCM-622.This phase heterogeneity is evidenced by the splitting of the(003)diffraction peak and a decrease in intensity during the H2-H3 phase transition,indicating the formation of lithium-rich/depleted domains.These findings establish a direct correlation between cathode composition,structural dynamics,and XFC performance,highlighting a critical trade-off between structural stability and fast-charging capability in nickel-rich layered oxides.
基金financial supports from the National Natural Science Foundation of China(Grant No.62335006,62275065,624B2050,62022032,and 62405078)Open Subject of Hebei Key Laboratory of Advanced Laser Technology and Equipment(HBKL-ALTE2025001)+2 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23144 and LBH-Z24155)Natural Science Foundation of Heilongjiang Province(Grant No.LH2024F031)China Postdoctoral Science Foundation(Grant No.2024M764172).
文摘In this paper,a fast step heterodyne light-induced thermoelastic spectroscopy(SH-LITES)sensor using a high-frequency quartz tuning fork(QTF)with resonant frequency of~100 kHz is reported for the first time.The theoretical principle of heterodyne LITES(H-LITES)signal generation is analyzed firstly,and an acetylene(C_(2)H_(2))H-LITES sensor is established to verify its performance.Experimental comparisons between the high-frequency QTF and a standard commercial QTF with resonant frequency of~32.768 kHz reveal that the high-frequency QTF exhibits a tenfold faster response time.Specifically,the H-LITES sensor with this QTF achieves a 33 ms measurement cycle,90%shorter than commercial counterparts.Furthermore,The SH-LITES technique is proposed to further shorten the scanning time to 15 ms,which achieves the shortest LITES measurement time known to date.To demonstrate its advantages in dynamic gas detection,an H_(2)O-LITES system integrating both QTF types is constructed for real-time monitoring of H_(2)O concentration during different respiration patterns.Comparative measurements show that the SH-LITES more accurately captures dynamic H_(2)O concentration fluctuations during respiration,outperforming the commercial QTF-based H-LITES sensor in rapid response scenarios.
