A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system ...A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system can be approximated by the solution of the simplified equations in the sense of mean square. An example is presented to illustrate the applications of the limit theorem.展开更多
Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described o...Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described on the basis of geometric singular perturbation theory. Then, the impact of time delay on the structure of the slow manifold of synchronized system is obtained by using the method of stability switch, and thus, time-delay effects on synchronization features are stated. It is shown the time delay cannot qualitatively affect the synchronization mechanism, however, it can result in the drift of the optimal coupling strength.展开更多
In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in te...In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in termsof mechanical properties were compared, and highly sig-nificant correlation between two systems were obtaineddespite some considerable differences in the measurementprinciples of KES - F and FAST systems.展开更多
BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effec...BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effectiveness of GLP-1RAs in these situations.AIM To evaluate the safety and efficacy of GLP-1RA in patients with T2DM fasting during Ramadan.METHODS Electronic databases were systematically searched for relevant studies that featured GLP-1RA in the intervention arm and other glucose-lowering medications in the control arm.The primary outcome was adverse events(AEs)during Ramadan for both groups;other outcomes included changes in glycemic and anthropometric measures during the peri-Ramadan period.RESULTS Four studies[three randomized-controlled trials with low risk of bias(RoB)and one prospective observational study with serious RoB]involving 754 subjects were analyzed.GLP-1RA group achieved greater glycated hemoglobin reduction than the non-GLP-1RA group[mean difference(MD):-0.31%,95%CI:-0.61 to-0.01,P=0.04,I2=77%]with a lower risk of documented symptomatic hypoglycemia(risk ratio=0.38,95%CI:0.16 to 0.88,P=0.02).Any AEs,serious AEs,or AEs that led to treatment discontinuation were comparable between the two groups.The GLP-1RA group experienced greater weight loss compared to the non-GLP-1RA group(MD:-2.0 kg,95%CI:-3.37 to-0.63,P=0.004,I2=95%).There were comparable changes in blood pressure and lipid profile between the two groups.GLP-1RA users experienced higher risks of gastrointestinal AEs,nausea,and vomiting;however,the risks of heartburn,abdominal pain,and diarrhea were similar in both groups.CONCLUSION Limited evidence suggests that GLP-1RAs are safe for T2DM management during Ramadan,offering modest benefits in blood sugar control and weight loss.Large multicenter trials are needed to confirm their safety and efficacy in at-risk populations,improving clinical practice decision-making.展开更多
With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter ...With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.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
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
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
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
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
To address the performance limitations of conventional LiPF6-carbonate electrolytes under extreme temperatures and high-rate charging,lithium difluoro(oxalato)borate(LiDFOB)is introduced into the LiPF6-carbonate elect...To address the performance limitations of conventional LiPF6-carbonate electrolytes under extreme temperatures and high-rate charging,lithium difluoro(oxalato)borate(LiDFOB)is introduced into the LiPF6-carbonate electrolyte to form a dual-salt system.The optimization mechanism enhancing the fast-charging capability of LiNi_(0.52)Co_(0.2)Mn_(0.28)O_(2)(NCM523)cathode is systematically explored.Molecular dynamics simulations and electrochemical characterization demonstrate the reconstruction of Li+solvation structures,expanding the voltage window and reducting Li^(+)desolvation barriers.In addition,the incorporation of LiDFOB induces the generation of a LiF/Li_(x)BO_(y)F_(z)-enriched cathode-electrolyte interphase,which effectively suppresses the dissolution of transition metals.In situ impedance measurements reveal the accelerated interfacial charge transfer kinetics.As expected,the NCM523 cathode achieves an 82%state-of-charge(SOC)in 12 min at 5 C(25°C)with 87%capacity retention after 100 cycles,and exhibits a 65%higher discharge capacity at 1 C than the baseline at−20°C.The 1 Ah pouch cells based on LiNi_(0.52)Co_(0.2)Mn_(0.28)O_(2)cathodes,graphite anodes,and 0.5 wt%LiDFOB-modified electrolyte demonstrate fast-charging capabilities:charging 97%of the pouch cell capacity within 30 min(2 C)and 80%within 15 min(4 C)at 25°C.This study offers a practical electrolyte design strategy that enhances the fast-charging performance of lithium-ion batteries(LIBs)over a wide temperature range(from−20 to 25°C).展开更多
基金supported by the National Nature Science Foundation of China (11372247 and 11102157)Program for NCET, the Shaanxi Project for Young New Star in Science and TechnologyNPU Foundation for Fundamental Research and SRF for ROCS, SEM
文摘A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system can be approximated by the solution of the simplified equations in the sense of mean square. An example is presented to illustrate the applications of the limit theorem.
文摘Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described on the basis of geometric singular perturbation theory. Then, the impact of time delay on the structure of the slow manifold of synchronized system is obtained by using the method of stability switch, and thus, time-delay effects on synchronization features are stated. It is shown the time delay cannot qualitatively affect the synchronization mechanism, however, it can result in the drift of the optimal coupling strength.
文摘In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in termsof mechanical properties were compared, and highly sig-nificant correlation between two systems were obtaineddespite some considerable differences in the measurementprinciples of KES - F and FAST systems.
基金thankful to Dr.Marina George Kudiyirickal MSc,MJDF-RCS,PhD for providing us the audio core tip of this article.
文摘BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effectiveness of GLP-1RAs in these situations.AIM To evaluate the safety and efficacy of GLP-1RA in patients with T2DM fasting during Ramadan.METHODS Electronic databases were systematically searched for relevant studies that featured GLP-1RA in the intervention arm and other glucose-lowering medications in the control arm.The primary outcome was adverse events(AEs)during Ramadan for both groups;other outcomes included changes in glycemic and anthropometric measures during the peri-Ramadan period.RESULTS Four studies[three randomized-controlled trials with low risk of bias(RoB)and one prospective observational study with serious RoB]involving 754 subjects were analyzed.GLP-1RA group achieved greater glycated hemoglobin reduction than the non-GLP-1RA group[mean difference(MD):-0.31%,95%CI:-0.61 to-0.01,P=0.04,I2=77%]with a lower risk of documented symptomatic hypoglycemia(risk ratio=0.38,95%CI:0.16 to 0.88,P=0.02).Any AEs,serious AEs,or AEs that led to treatment discontinuation were comparable between the two groups.The GLP-1RA group experienced greater weight loss compared to the non-GLP-1RA group(MD:-2.0 kg,95%CI:-3.37 to-0.63,P=0.004,I2=95%).There were comparable changes in blood pressure and lipid profile between the two groups.GLP-1RA users experienced higher risks of gastrointestinal AEs,nausea,and vomiting;however,the risks of heartburn,abdominal pain,and diarrhea were similar in both groups.CONCLUSION Limited evidence suggests that GLP-1RAs are safe for T2DM management during Ramadan,offering modest benefits in blood sugar control and weight loss.Large multicenter trials are needed to confirm their safety and efficacy in at-risk populations,improving clinical practice decision-making.
基金co-supported by the National Natural Science Foundation of China(No.52477063)the National Key Research and Development Program of China(No.2023YFF0719100)。
文摘With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.
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.
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.
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.
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.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52372191)the National Natural Science Foundation of China (Grant No. 22271106)+2 种基金the National Science Foundation of China (Grant Nos. 52073286 (C.-Z.L.), 22275185 (C.-Z.L.))the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ115 (C.-Z.L.)the XMIREM Autonomously Deployment Project (2023GG01 (C.-Z.L.))
文摘To address the performance limitations of conventional LiPF6-carbonate electrolytes under extreme temperatures and high-rate charging,lithium difluoro(oxalato)borate(LiDFOB)is introduced into the LiPF6-carbonate electrolyte to form a dual-salt system.The optimization mechanism enhancing the fast-charging capability of LiNi_(0.52)Co_(0.2)Mn_(0.28)O_(2)(NCM523)cathode is systematically explored.Molecular dynamics simulations and electrochemical characterization demonstrate the reconstruction of Li+solvation structures,expanding the voltage window and reducting Li^(+)desolvation barriers.In addition,the incorporation of LiDFOB induces the generation of a LiF/Li_(x)BO_(y)F_(z)-enriched cathode-electrolyte interphase,which effectively suppresses the dissolution of transition metals.In situ impedance measurements reveal the accelerated interfacial charge transfer kinetics.As expected,the NCM523 cathode achieves an 82%state-of-charge(SOC)in 12 min at 5 C(25°C)with 87%capacity retention after 100 cycles,and exhibits a 65%higher discharge capacity at 1 C than the baseline at−20°C.The 1 Ah pouch cells based on LiNi_(0.52)Co_(0.2)Mn_(0.28)O_(2)cathodes,graphite anodes,and 0.5 wt%LiDFOB-modified electrolyte demonstrate fast-charging capabilities:charging 97%of the pouch cell capacity within 30 min(2 C)and 80%within 15 min(4 C)at 25°C.This study offers a practical electrolyte design strategy that enhances the fast-charging performance of lithium-ion batteries(LIBs)over a wide temperature range(from−20 to 25°C).
