The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been d...The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been demonstrated that pulsed electric current can effectively address the issue of embrittlement in RPV steel.However,the relationship between pulse parameters(duty ratio,frequency,current,and time)and the effectiveness of pulse current processing has not been systematically studied.The application of machine learning methods enables autonomous exploration and learning of the relationship between data.Consequently,this study proposes a machine learning method based on the random forest model to establish the relationship between the parameters of electrical pulses and the repair effect of RPV steel.A generative adversarial network is employed to enhance data diversity and scalability,while a particle swarm optimization algorithm is utilized to optimize the initialization weights and biases of the random forest model,aiming to improve the model’s fitting ability and training performance.The results indicate that the coefficient of determination R-square(R^(2)),root mean squared error and mean absolute error values are 0.934,0.045,and 0.036,respectively,suggesting that the model has the potential to predict the performance recovery of RPV steel after pulsed electric field treatment.The prediction of the impact of pulse current parameters on the repair effect will help to enhance and optimize the repair process,thereby providing a scientific basis for pulse current repair processing.展开更多
Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying...Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying temperature conditions.Specifically,while the RO system performs well under high temperatures,its efficiency decreases sharply at lower temperatures.Membrane capacitive deionization(MCDI)is considered as an emergent and promising technology for brackish water desalination.While plenty of studies have been devoted to investigating the impacts of raw water properties(e.g.,salinity,coexisting ions,and natural organic matter)on MCDI performance,the role of water temperatures during the desalination remains under-explored.In this study,we first tested and determined the optimized MCDI operation parameters,such as the cell voltage and feedwater flow rate.Key findings showed that MCDI’s salt removal efficiency remains unaffected by feedwater temperature fluctuations.However,as feedwater temperature increases from 15℃to 40℃,the specific energy consumption for desalination slightly rises by 16.3%,and current efficiency drops by 14.1%.Compared to RO systems,the resilience of MCDI to temperature fluctuations makes it a preferable choice for brackish water treatment in areas with a large temperature difference.展开更多
This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramia...This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.展开更多
Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislo...Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislocations at different temperatures were investigated.Results show that a mapping relationship between process parameters and grain refinement/coarsening is established,and the optimal processing temperature coefficient is 0.23.Compared with the cases with processing temperature coefficient of 0.19,0.20,0.21,0.25,and 0.27,the refinement effect increases by 256.0%,146.0%,113.0%,6.7%,and 52.4%,respectively.Excessively high temperatures lead to grain coarsening due to dislocation annihilation,and the application of strain can reduce the actual melting point of materials.Even if the processing temperature does not exceed the theoretical melting point,remelting and crystallization may still occur,resulting in an overburning phenomenon that reduces internal defects and increases overall grain size.This research is of great significance for the actual forging process design.展开更多
To address the challenges of complex metallic film coating processes and low integration in single-parameter detection for existing photonic crystal fiber surface plasmon resonance(PCF-SPR)sensors,a dual-parameter sen...To address the challenges of complex metallic film coating processes and low integration in single-parameter detection for existing photonic crystal fiber surface plasmon resonance(PCF-SPR)sensors,a dual-parameter sensor based on gold nanowire-integrated bias-core PCF-SPR is proposed.Unlike conventional in-hole coatings or metallic film structures,the gold nanowires are directly attached to the fiber cladding via chemical vapor deposition(CVD),eliminating uneven coating issues and significantly simplifying fabrica-tion.By optimizing the asymmetric bias-core fiber structure and leveraging the strong localized field en-hancement of gold nanowires,the sensor achieves high-sensitivity synchronous detection of temperature(25−60℃)and refractive index(1.31−1.40)in dual-polarization modes.The simulation results demonstrate that the x-polarization mode can achieve 1.31−1.40 refractive index detection with maximum wavelength sensitivity and amplitude sensitivity of 14800 nm/RIU and−1724.25 RIU^(−1),and maximum refractive index resolution of 6.75×10^(−6)RIU.The y-polarization mode achieves refractive index detection range of 1.34−1.40,and the maximum wavelength sensitivity and amplitude sensitivity are 28400 nm/RIU and−1298.93 RIU^(−1),and the maximum refractive index resolution is 3.52×10^(−6)RIU.For temperature sensing,the sensor exhibits a wavelength sensitivity of 7.8 nm/℃and a high resolution of 1.38×10^(−6)℃over the range of 25−60℃.This design synergizes gold nanowires and the bias-core architecture to simplify fabrication while enabling multi-parameter detection.The proposed sensor offers new insights for integrated applications in biochemical mon-itoring,environmental sensing,and related fields.展开更多
With the evolution of next-generation network technologies,the complexity of network management has significantly increased,and the means of network attacks are diversified,bringing new challenges to network traffic c...With the evolution of next-generation network technologies,the complexity of network management has significantly increased,and the means of network attacks are diversified,bringing new challenges to network traffic classification.This paper presents a general AIdriven network traffic classification workflow and elaborates on a traffic data and feature engineering framework.Most importantly,it analyzes the concept and causes of data distribution shifts in ne twork traffic,proposing detection methods and countermeasures.Experimental results on real traffic collected at different time intervals show that application evolution can induce data distribution shifts,which in turn lead to a noticeable degradation in traffic classification performance.Comparative drift detection experiments further confirm that such shifts are more evident over long-term intervals,while short-term traffic remains relatively stable.These findings demonstrate the necessity of incorporating drift-aware mechanisms into AI-driven network traffic classification systems.展开更多
Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materi...Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.展开更多
Lin Wei is a hiking enthusiast.At six o'clock on the last Saturday morning,the temperature at the foot of the mountain was only 2℃,so she put on her thickest fleece jacket.However,after only half an hour of climb...Lin Wei is a hiking enthusiast.At six o'clock on the last Saturday morning,the temperature at the foot of the mountain was only 2℃,so she put on her thickest fleece jacket.However,after only half an hour of climbing,the heat left her drenched in sweat,making her feel very cold.By midday,the temperature was approaching 20℃,and her heavy jacket had to be tied around her waist,becoming a burden during her hike.This outdoor adventure allowed her to appreciate the beautiful scenery,but also subjected her to repeated changes in temperature.展开更多
Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study ut...Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study utilized observational data and two new generation reanalysis products(i.e.,the fifth major global reanalysis produced by ECMWF(ERA5)and the Japanese Reanalysis for Three Quarters of a Century(JRA-3Q))to investigate the shift changes in precipitation in NEC around 2000 and associated water vapor transport.The analysis identified a pivotal interdecadal shift in 1998/99,transitioning from moderate increases(17.5 mm/10 yr during 1980-1998)to accelerated but more variable precipitation growth(85.4 mm/10 yr post-1999).While the mean precipitation during the post-shift period decreased,enhanced anticyclonic circulation amplified moisture divergence over continental NEC,redirecting vapor flux toward coastal regions.Crucially,trajectory analysis demonstrated regime-dependent moisture sourcing:midlatitude westerlies dominated during wet extremes(44% of trajectories in 1998),whereas East Asian monsoon flows prevailed in drought years(36% of trajectories in 2007).The post-1998 period exhibited increased reliance on localized recycling(45%of mid-tropospheric trajectories),reflecting weakened monsoonal inflow.These findings highlight NEC’s growing vulnerability to competing moisture pathways and atmospheric blocking-a dual mechanism that explains rising extremes despite declining mean precipitation.By reconciling dataset discrepancies(ERA5 vs.JRA-3Q trends)and elucidating circulation-precipitation linkages,this work provides actionable insights for climate-resilient agriculture in NEC’s water-stressed ecosystems.展开更多
Objective:To investigate the distribution of Traditional Chinese Medicine(TCM)constitution among night-shift nurses at a public tertiary-level Class A hospital,thereby identifying new approaches for developing effecti...Objective:To investigate the distribution of Traditional Chinese Medicine(TCM)constitution among night-shift nurses at a public tertiary-level Class A hospital,thereby identifying new approaches for developing effective interventions to enhance their health status.Methods:A total of 601 nurses employed at a public tertiary-level Class A hospital from August 2024 to August 2025 participated in the survey.Analysis was conducted using the Traditional Chinese Medicine Constitution Questionnaire.Results:The most prevalent TCM constitution types among night-shift nurses were Yang Deficiency Constitution(50.4%),Yin Deficiency Constitution(49.8%),Qi Deficiency Constitution(45.4%),and Phlegm-Dampness Constitution(45.1%).Conclusion:A high proportion of clinical night-shift nursing staff exhibit imbalanced constitution types,severely impacting their physical and mental health.Nursing administrators should implement targeted TCM constitution-based health maintenance and regulation to improve the health status of nursing personnel.展开更多
In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperat...In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.展开更多
As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpi...As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpine plant distribution and their profound impact on fragile ecosystems have become a focus of ecological research and conservation efforts,with increasing urgency.Meconopsis,a typical representative of Chinese alpine plants,exhibits diverse adaptability,making it an ideal model for studying how alpine species respond to extreme environmental changes.A lack of comprehensive genus-level analyses may hinder the development of long-term conservation and management strategies.Given the genus's ecological importance,vulnerability,and the risk of trait homogenization in genus-level modeling,there is an urgent need to assess its future distribution patterns,migration trends,and adaptive mechanisms based on habitat classification.In this study,we employed the Maxent model,integrating multidimensional environmental variables,to develop genus-level models and representative habitat-based models(forest,meadows,and periglacial).Results indicate a northwestward expansion and southeastward contraction of suitable habitats under future climate scenarios,with migration patterns in latitude and elevation showing stage-specific characteristics.Key environmental factors varied across models but were mostly associated with seasonal growth traits and microhabitat conditions,highlighting both the universal ecological requirements and niche differentiation within Meconopsis.Based on these findings,we propose a dynamic conservation strategy framework informed by stage-specific responses and habitat differences.Future efforts should focus on incorporating alpine-specific environmental variables and optimizing specimen collection strategies to enhance model performance and support landscape planning and biodiversity conservation.展开更多
Heat-induced emission peak shift(HIEPS),encompassing both redshift and blueshift,remains mechanistically unresolved in phosphor materials.Using state-of-the-art first-principles calculations of M_(2)SiO_(4):Eu^(2+)(M=...Heat-induced emission peak shift(HIEPS),encompassing both redshift and blueshift,remains mechanistically unresolved in phosphor materials.Using state-of-the-art first-principles calculations of M_(2)SiO_(4):Eu^(2+)(M=Sr,Ba,Ca),we reveal that conventional thermal expansion theory cannot adequately explain these phenomena.Instead,our frozen phonon analysis identifies local electron-phonon coupling as the dominant mechanism,where anisotropic thermal vibrations selectively distort the asymmetric Eu-5d potential well that arises from the dopant’s coordination environment.This distortion manifests through the temperature-sensitiveΔ_(f−d) parameter governing the 5d→4f transition energy,directly controlling spectral shifts.Our findings establish a universal framework for HIEPS in rare-earth phosphors and enable a Δ_(f−d)-guided strategy for designing thermally stable phosphors.展开更多
Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on thes...Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on these characteristics.This study aimed to characterize spikelet filling in early-season rice and identify the key factors contributing to its improvement.Field experiments were conducted over two years(2021 and 2022)to mainly investigate the proportions of fully-filled,partially-filled,and empty spikelets,along with the biomass-fertilized spikelet ratio and harvest index,in 11 early-season rice varieties.The results revealed significant varietal variation in spikelet filling,with the proportion of fully-filled spikelets ranging from 60.6%to 81.1%in 2021 and from 66.3%to 79.2%in 2022.Among the 11 varieties,Liangyou 42,Lingliangyou 942,and Liangyou 287 exhibited relatively superior performance in spikelet filling.Linear regression revealed that,although a significant negative relationship existed between the proportion of fully-filled spikelets and both partially-filled and empty spikelets,the relationship with partially-filled spikelets was stronger.Additionally,the proportion of fully-filled spikelets showed a significant positive relationship with the harvest index but not with the biomass-fertilized spikelet ratio.These findings indicate that increasing the harvest index and reducing the occurrence of partially-filled grains are essential strategies for improving spikelet filling in early-season rice.展开更多
Prolonged exposure to n-butanol, a common hazardous volatile organic compound(VOC) in the environment, can lead to a broad range of adverse health effects. Therefore, detecting n-butanol safely and efficiently at low ...Prolonged exposure to n-butanol, a common hazardous volatile organic compound(VOC) in the environment, can lead to a broad range of adverse health effects. Therefore, detecting n-butanol safely and efficiently at low concentrations becomes critical for both environmental monitoring and human health. In this study, a novel Eu/Ce-codoped MOF-ZnO gas sensor was developed for the sensitive detection of n-butanol gas under ultraviolet activation at ambient temperature. A series of Eu/Ce-ZnO nanomaterials were synthesized via a simple co-precipitation route, by carefully designing the varied mass ratios of Eu and Ce incorporated into pristine ZnO derived from MOF precursors. The gas testing results revealed that introducing an appropriate amount of Eu and Ce would enlarge the specific surface area and enrich the oxygen vacancy content compared to pristine MOF-ZnO. Upon UV irradiation, the 0.03 wt% Eu 0.04 wt% Ce-ZnO sensor achieved a superior response of 611 for100 ppm n-butanol at room temperature, 15.28 times higher than that of pristine MOF-ZnO(40). Furthermore, the sensor presented rapid response/recovery times(15 s/28 s) and excellent selectivity. The above contributions pave the way for the promising development of highly sensitive, ultraviolet-enhanced gas sensors for ambient temperature detection of VOCs.展开更多
When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.Howe...When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.展开更多
With the development of electronic technologies,piezoresistive sensors have attracted increasing attention.Among them,aerogels with high elasticity,as a type of three-dimensional porous material,are widely used in the...With the development of electronic technologies,piezoresistive sensors have attracted increasing attention.Among them,aerogels with high elasticity,as a type of three-dimensional porous material,are widely used in the field of piezoresistive sensors.Nowadays,with the extension of science and technology areas,fields involving low-temperature environments have emerged,which has led to an increasing demand for piezoresistive sensors that can serve at cryogenic temperatures.However,most studies on aerogels have only focused on their sensing performance at room temperature,and there is a lack of research on aerogel sensors that can work at low temperatures.In this work,piezoresistive sensors based on cotton fibers were proposed for applications at 77 K.As one of the most important natural polymers,cotton fibers have the ability to maintain elasticity at very low temperatures.Cotton fiber-based aerogels with high elasticity and cyclic stability were obtained by controlling the freeze-casting parameters and size distribution of cotton fibers,and they showed excellent pressure sensing properties,including a wide sensing range and remarkable long-term stability.This study bridges the gap in cryogenic sensing materials and provides insights into microstructure-property relationships,advancing applications in aerospace and cryogenic engineering.展开更多
Following over 20 years of research,a direct measurement of the QGP temperature has been achieved at Relativistic Heavy-Ion Collider(RHIC),free from the blue-shift effect and contamination from strong interactions.Thi...Following over 20 years of research,a direct measurement of the QGP temperature has been achieved at Relativistic Heavy-Ion Collider(RHIC),free from the blue-shift effect and contamination from strong interactions.This viewpoint discusses a recent measurement of the QGP temperature at different stages at the Solenoidal Tracker at RHIC(STAR),which used e^(+)e^(-)pairs as penetrating probes.展开更多
This investigation utilizes non-equilibrium molecular dynamics(NEMD)simulations to explore shockinduced spallation in single-crystal tantalumacross shock velocities of 0.75–4 km/s and initial temperatures from300 to ...This investigation utilizes non-equilibrium molecular dynamics(NEMD)simulations to explore shockinduced spallation in single-crystal tantalumacross shock velocities of 0.75–4 km/s and initial temperatures from300 to 2000 K.Two spallation modes emerge:classical spallation for shock velocity below 1.5 km/s,with solid-state reversible Body-Centered Cubic(BCC)to Face-Centered Cubic(FCC)orHexagonal Close-Packed(HCP)phase transformations and discrete void nucleation-coalescence;micro-spallation for shock velocity above 3.0 km/s,featuring complete shock-induced melting and fragmentation,with a transitional regime(2.0-2.5 km/s)of partial melting.Spall strength decreases monotonically with temperature due to thermal softening.Elevated temperatures delay void nucleation but increase density,expanding spall regions and enhancing structural disorder with reduced BCC recovery.For microspallation,melting exacerbates damage,causing smaller voids and intensified atomic ejection,which increases with temperature.Free surface velocity profiles indicate damage:in classical spallation,first drop marks nucleation,and pullback signals spall layers.In micro-spallation,the first drop is irrelevant,but remains valid.Temperature delays pullback signals and weakens Hugoniot Elastic Limit.This study clarifies temperature-shock coupling in Ta spallation,aiding failure prediction in high-temperature shock environments.展开更多
Biological invasion is a pressing environmental and ecological challenge worldwide.Cabomba caroliniana(C.caroliniana),a submerged macrophyte native to South America,is listed as a high-priority invasive species in sev...Biological invasion is a pressing environmental and ecological challenge worldwide.Cabomba caroliniana(C.caroliniana),a submerged macrophyte native to South America,is listed as a high-priority invasive species in several countries.It is critical to understand how water temperature influences its invasiveness for effective management.However,research on the effects of water temperature on C.caroliniana the growth is limited.This study used controlled experiments to examine how water temperature(5-30℃)affects the morphological,physiological,photosynthetic,and stoichiometric traits of C.caroliniana.The results showed that broad water temperature tolerance of C.caroliniana significantly impacts its reproductive capacity and invasive potential.At 5-10℃,cold stress induced carotenoid synthesis and total organic carbon accumulation,enabling adaptation to low temperatures.However,C.caroliniana grew slowly,as its root development was limited,and its invasiveness remained low.At 20-30℃,increased chlorophyll synthesis and enhanced resource-use efficiency supported rapid growth,including more branches,leading to high invasion and dispersal potential.Thus,C.caroliniana exhibited strong colonization and spread quickly in tropical and subtropical waters(>20℃).In temperate zones,populations can be established during summer(20-25℃)and survive winter hrough cold adaptation.We recommended prioritizing control measures during warm seasons(20-30℃)to disrupt propagule dispersal,alongside early monitoring in temperate waters to inhibit ecological invasion.展开更多
基金financially supported by the National Natural Science Foundation of China(U21B2082,52474410)the National Key R&D Program of China(2023YFB3709903,2020 YFA0714900)+5 种基金the Key R&D Program of Shandong Province,China(2023CXGC010406)the Scientific Research Special Project for First-Class Disciplines in Inner Mongolia Autonomous Region(YLXKZXNKD-001)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(2024ZD06)the Technology Support Project for the Construction of Major Innovation Platforms in Inner Mongolia Autonomous Region(XM2024XTGXQ16)the Beijing Municipal Natural Science Foundation(2222065)the Fundamental Research Funds for the Central Universities(FRF-TP-22-02C2).
文摘The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been demonstrated that pulsed electric current can effectively address the issue of embrittlement in RPV steel.However,the relationship between pulse parameters(duty ratio,frequency,current,and time)and the effectiveness of pulse current processing has not been systematically studied.The application of machine learning methods enables autonomous exploration and learning of the relationship between data.Consequently,this study proposes a machine learning method based on the random forest model to establish the relationship between the parameters of electrical pulses and the repair effect of RPV steel.A generative adversarial network is employed to enhance data diversity and scalability,while a particle swarm optimization algorithm is utilized to optimize the initialization weights and biases of the random forest model,aiming to improve the model’s fitting ability and training performance.The results indicate that the coefficient of determination R-square(R^(2)),root mean squared error and mean absolute error values are 0.934,0.045,and 0.036,respectively,suggesting that the model has the potential to predict the performance recovery of RPV steel after pulsed electric field treatment.The prediction of the impact of pulse current parameters on the repair effect will help to enhance and optimize the repair process,thereby providing a scientific basis for pulse current repair processing.
基金supported by the National Natural Science Foundation of China(Nos.52370090,52300016)China Postdoctoral Science Foundation(Nos.2023M733379,2024M753122).
文摘Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying temperature conditions.Specifically,while the RO system performs well under high temperatures,its efficiency decreases sharply at lower temperatures.Membrane capacitive deionization(MCDI)is considered as an emergent and promising technology for brackish water desalination.While plenty of studies have been devoted to investigating the impacts of raw water properties(e.g.,salinity,coexisting ions,and natural organic matter)on MCDI performance,the role of water temperatures during the desalination remains under-explored.In this study,we first tested and determined the optimized MCDI operation parameters,such as the cell voltage and feedwater flow rate.Key findings showed that MCDI’s salt removal efficiency remains unaffected by feedwater temperature fluctuations.However,as feedwater temperature increases from 15℃to 40℃,the specific energy consumption for desalination slightly rises by 16.3%,and current efficiency drops by 14.1%.Compared to RO systems,the resilience of MCDI to temperature fluctuations makes it a preferable choice for brackish water treatment in areas with a large temperature difference.
文摘This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.
基金National Natural Science Foundation of China(52375394,52275390,U23A20628,52305429)Major Project of Science and Technology in Shanxi(202301050201004)Natural Science Foundation of Shanxi Province(202403021222132)。
文摘Using multi-directional forging temperature as the independent variable and adopting the dual-mode phase field crystal model,the nucleation modes,reaction mechanisms,and interactions between grain boundaries and dislocations at different temperatures were investigated.Results show that a mapping relationship between process parameters and grain refinement/coarsening is established,and the optimal processing temperature coefficient is 0.23.Compared with the cases with processing temperature coefficient of 0.19,0.20,0.21,0.25,and 0.27,the refinement effect increases by 256.0%,146.0%,113.0%,6.7%,and 52.4%,respectively.Excessively high temperatures lead to grain coarsening due to dislocation annihilation,and the application of strain can reduce the actual melting point of materials.Even if the processing temperature does not exceed the theoretical melting point,remelting and crystallization may still occur,resulting in an overburning phenomenon that reduces internal defects and increases overall grain size.This research is of great significance for the actual forging process design.
文摘To address the challenges of complex metallic film coating processes and low integration in single-parameter detection for existing photonic crystal fiber surface plasmon resonance(PCF-SPR)sensors,a dual-parameter sensor based on gold nanowire-integrated bias-core PCF-SPR is proposed.Unlike conventional in-hole coatings or metallic film structures,the gold nanowires are directly attached to the fiber cladding via chemical vapor deposition(CVD),eliminating uneven coating issues and significantly simplifying fabrica-tion.By optimizing the asymmetric bias-core fiber structure and leveraging the strong localized field en-hancement of gold nanowires,the sensor achieves high-sensitivity synchronous detection of temperature(25−60℃)and refractive index(1.31−1.40)in dual-polarization modes.The simulation results demonstrate that the x-polarization mode can achieve 1.31−1.40 refractive index detection with maximum wavelength sensitivity and amplitude sensitivity of 14800 nm/RIU and−1724.25 RIU^(−1),and maximum refractive index resolution of 6.75×10^(−6)RIU.The y-polarization mode achieves refractive index detection range of 1.34−1.40,and the maximum wavelength sensitivity and amplitude sensitivity are 28400 nm/RIU and−1298.93 RIU^(−1),and the maximum refractive index resolution is 3.52×10^(−6)RIU.For temperature sensing,the sensor exhibits a wavelength sensitivity of 7.8 nm/℃and a high resolution of 1.38×10^(−6)℃over the range of 25−60℃.This design synergizes gold nanowires and the bias-core architecture to simplify fabrication while enabling multi-parameter detection.The proposed sensor offers new insights for integrated applications in biochemical mon-itoring,environmental sensing,and related fields.
基金supported by ZTE Industry-University-Institute Cooperation Funds under Grant No.HC-CN-20220607009。
文摘With the evolution of next-generation network technologies,the complexity of network management has significantly increased,and the means of network attacks are diversified,bringing new challenges to network traffic classification.This paper presents a general AIdriven network traffic classification workflow and elaborates on a traffic data and feature engineering framework.Most importantly,it analyzes the concept and causes of data distribution shifts in ne twork traffic,proposing detection methods and countermeasures.Experimental results on real traffic collected at different time intervals show that application evolution can induce data distribution shifts,which in turn lead to a noticeable degradation in traffic classification performance.Comparative drift detection experiments further confirm that such shifts are more evident over long-term intervals,while short-term traffic remains relatively stable.These findings demonstrate the necessity of incorporating drift-aware mechanisms into AI-driven network traffic classification systems.
文摘Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.
文摘Lin Wei is a hiking enthusiast.At six o'clock on the last Saturday morning,the temperature at the foot of the mountain was only 2℃,so she put on her thickest fleece jacket.However,after only half an hour of climbing,the heat left her drenched in sweat,making her feel very cold.By midday,the temperature was approaching 20℃,and her heavy jacket had to be tied around her waist,becoming a burden during her hike.This outdoor adventure allowed her to appreciate the beautiful scenery,but also subjected her to repeated changes in temperature.
基金supported by the National Natural Science Foundation of China[grant numbers 42275185 and 42205032]the Fundamental Research Funds for the Central Universities[grant number B250201118]。
文摘Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study utilized observational data and two new generation reanalysis products(i.e.,the fifth major global reanalysis produced by ECMWF(ERA5)and the Japanese Reanalysis for Three Quarters of a Century(JRA-3Q))to investigate the shift changes in precipitation in NEC around 2000 and associated water vapor transport.The analysis identified a pivotal interdecadal shift in 1998/99,transitioning from moderate increases(17.5 mm/10 yr during 1980-1998)to accelerated but more variable precipitation growth(85.4 mm/10 yr post-1999).While the mean precipitation during the post-shift period decreased,enhanced anticyclonic circulation amplified moisture divergence over continental NEC,redirecting vapor flux toward coastal regions.Crucially,trajectory analysis demonstrated regime-dependent moisture sourcing:midlatitude westerlies dominated during wet extremes(44% of trajectories in 1998),whereas East Asian monsoon flows prevailed in drought years(36% of trajectories in 2007).The post-1998 period exhibited increased reliance on localized recycling(45%of mid-tropospheric trajectories),reflecting weakened monsoonal inflow.These findings highlight NEC’s growing vulnerability to competing moisture pathways and atmospheric blocking-a dual mechanism that explains rising extremes despite declining mean precipitation.By reconciling dataset discrepancies(ERA5 vs.JRA-3Q trends)and elucidating circulation-precipitation linkages,this work provides actionable insights for climate-resilient agriculture in NEC’s water-stressed ecosystems.
文摘Objective:To investigate the distribution of Traditional Chinese Medicine(TCM)constitution among night-shift nurses at a public tertiary-level Class A hospital,thereby identifying new approaches for developing effective interventions to enhance their health status.Methods:A total of 601 nurses employed at a public tertiary-level Class A hospital from August 2024 to August 2025 participated in the survey.Analysis was conducted using the Traditional Chinese Medicine Constitution Questionnaire.Results:The most prevalent TCM constitution types among night-shift nurses were Yang Deficiency Constitution(50.4%),Yin Deficiency Constitution(49.8%),Qi Deficiency Constitution(45.4%),and Phlegm-Dampness Constitution(45.1%).Conclusion:A high proportion of clinical night-shift nursing staff exhibit imbalanced constitution types,severely impacting their physical and mental health.Nursing administrators should implement targeted TCM constitution-based health maintenance and regulation to improve the health status of nursing personnel.
基金supported by the National Natural Science Foundation of China (Grant Nos.12074213 and 11574108)the Major Basic Program of Natural Science Foundation of Shandong Province (Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province (Grant No.ZR2023MA082)。
文摘In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.
文摘As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpine plant distribution and their profound impact on fragile ecosystems have become a focus of ecological research and conservation efforts,with increasing urgency.Meconopsis,a typical representative of Chinese alpine plants,exhibits diverse adaptability,making it an ideal model for studying how alpine species respond to extreme environmental changes.A lack of comprehensive genus-level analyses may hinder the development of long-term conservation and management strategies.Given the genus's ecological importance,vulnerability,and the risk of trait homogenization in genus-level modeling,there is an urgent need to assess its future distribution patterns,migration trends,and adaptive mechanisms based on habitat classification.In this study,we employed the Maxent model,integrating multidimensional environmental variables,to develop genus-level models and representative habitat-based models(forest,meadows,and periglacial).Results indicate a northwestward expansion and southeastward contraction of suitable habitats under future climate scenarios,with migration patterns in latitude and elevation showing stage-specific characteristics.Key environmental factors varied across models but were mostly associated with seasonal growth traits and microhabitat conditions,highlighting both the universal ecological requirements and niche differentiation within Meconopsis.Based on these findings,we propose a dynamic conservation strategy framework informed by stage-specific responses and habitat differences.Future efforts should focus on incorporating alpine-specific environmental variables and optimizing specimen collection strategies to enhance model performance and support landscape planning and biodiversity conservation.
基金supported by the National Natural Science Foundation(NSF)of China(62475265,22031009,22075282,12404064)the National Key Research and Development Program of China(2021YFB3601501)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB1170000)NSF of Fujian Province(2023J01212,2024J08106).
文摘Heat-induced emission peak shift(HIEPS),encompassing both redshift and blueshift,remains mechanistically unresolved in phosphor materials.Using state-of-the-art first-principles calculations of M_(2)SiO_(4):Eu^(2+)(M=Sr,Ba,Ca),we reveal that conventional thermal expansion theory cannot adequately explain these phenomena.Instead,our frozen phonon analysis identifies local electron-phonon coupling as the dominant mechanism,where anisotropic thermal vibrations selectively distort the asymmetric Eu-5d potential well that arises from the dopant’s coordination environment.This distortion manifests through the temperature-sensitiveΔ_(f−d) parameter governing the 5d→4f transition energy,directly controlling spectral shifts.Our findings establish a universal framework for HIEPS in rare-earth phosphors and enable a Δ_(f−d)-guided strategy for designing thermally stable phosphors.
基金funded by the Earmarked Fund for China Agriculture Research System,grant number CARS-01-33.
文摘Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on these characteristics.This study aimed to characterize spikelet filling in early-season rice and identify the key factors contributing to its improvement.Field experiments were conducted over two years(2021 and 2022)to mainly investigate the proportions of fully-filled,partially-filled,and empty spikelets,along with the biomass-fertilized spikelet ratio and harvest index,in 11 early-season rice varieties.The results revealed significant varietal variation in spikelet filling,with the proportion of fully-filled spikelets ranging from 60.6%to 81.1%in 2021 and from 66.3%to 79.2%in 2022.Among the 11 varieties,Liangyou 42,Lingliangyou 942,and Liangyou 287 exhibited relatively superior performance in spikelet filling.Linear regression revealed that,although a significant negative relationship existed between the proportion of fully-filled spikelets and both partially-filled and empty spikelets,the relationship with partially-filled spikelets was stronger.Additionally,the proportion of fully-filled spikelets showed a significant positive relationship with the harvest index but not with the biomass-fertilized spikelet ratio.These findings indicate that increasing the harvest index and reducing the occurrence of partially-filled grains are essential strategies for improving spikelet filling in early-season rice.
基金supported by the National Natural Science Foundation of China (Grant No. 12304467)the China Postdoctoral Science Foundation (Grant No. 2023M732175)。
文摘Prolonged exposure to n-butanol, a common hazardous volatile organic compound(VOC) in the environment, can lead to a broad range of adverse health effects. Therefore, detecting n-butanol safely and efficiently at low concentrations becomes critical for both environmental monitoring and human health. In this study, a novel Eu/Ce-codoped MOF-ZnO gas sensor was developed for the sensitive detection of n-butanol gas under ultraviolet activation at ambient temperature. A series of Eu/Ce-ZnO nanomaterials were synthesized via a simple co-precipitation route, by carefully designing the varied mass ratios of Eu and Ce incorporated into pristine ZnO derived from MOF precursors. The gas testing results revealed that introducing an appropriate amount of Eu and Ce would enlarge the specific surface area and enrich the oxygen vacancy content compared to pristine MOF-ZnO. Upon UV irradiation, the 0.03 wt% Eu 0.04 wt% Ce-ZnO sensor achieved a superior response of 611 for100 ppm n-butanol at room temperature, 15.28 times higher than that of pristine MOF-ZnO(40). Furthermore, the sensor presented rapid response/recovery times(15 s/28 s) and excellent selectivity. The above contributions pave the way for the promising development of highly sensitive, ultraviolet-enhanced gas sensors for ambient temperature detection of VOCs.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400000)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021253)+1 种基金the Major Science and Technology Projects of China National Offshore Oil Corporation Limited during the 14th Five Year Plan(No.KJGG-2022-12-CCUS-030500)the Photon Science Center for Carbon Neutrality of Chinese Academy of Science.
文摘When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.
基金financially supported by the National Natural Science Foundation of China(No.52073294)National Key R&D Program of China(No.2021YFB4000700)+1 种基金Project of Stable Support for Youth Team in Basic Research Field of the Chinese Academy of Sciences,China(No.YSBR-017)The authors are highly grateful to Mr.Fan-Ming Zhao for Cryogenic Mechanical Testing.
文摘With the development of electronic technologies,piezoresistive sensors have attracted increasing attention.Among them,aerogels with high elasticity,as a type of three-dimensional porous material,are widely used in the field of piezoresistive sensors.Nowadays,with the extension of science and technology areas,fields involving low-temperature environments have emerged,which has led to an increasing demand for piezoresistive sensors that can serve at cryogenic temperatures.However,most studies on aerogels have only focused on their sensing performance at room temperature,and there is a lack of research on aerogel sensors that can work at low temperatures.In this work,piezoresistive sensors based on cotton fibers were proposed for applications at 77 K.As one of the most important natural polymers,cotton fibers have the ability to maintain elasticity at very low temperatures.Cotton fiber-based aerogels with high elasticity and cyclic stability were obtained by controlling the freeze-casting parameters and size distribution of cotton fibers,and they showed excellent pressure sensing properties,including a wide sensing range and remarkable long-term stability.This study bridges the gap in cryogenic sensing materials and provides insights into microstructure-property relationships,advancing applications in aerospace and cryogenic engineering.
文摘Following over 20 years of research,a direct measurement of the QGP temperature has been achieved at Relativistic Heavy-Ion Collider(RHIC),free from the blue-shift effect and contamination from strong interactions.This viewpoint discusses a recent measurement of the QGP temperature at different stages at the Solenoidal Tracker at RHIC(STAR),which used e^(+)e^(-)pairs as penetrating probes.
基金funded by the Changsha Municipal Natural Science Foundation(Grant No.kq2402024)Chengdu Polytechnic Scientific Research Platform(23KYPT01).
文摘This investigation utilizes non-equilibrium molecular dynamics(NEMD)simulations to explore shockinduced spallation in single-crystal tantalumacross shock velocities of 0.75–4 km/s and initial temperatures from300 to 2000 K.Two spallation modes emerge:classical spallation for shock velocity below 1.5 km/s,with solid-state reversible Body-Centered Cubic(BCC)to Face-Centered Cubic(FCC)orHexagonal Close-Packed(HCP)phase transformations and discrete void nucleation-coalescence;micro-spallation for shock velocity above 3.0 km/s,featuring complete shock-induced melting and fragmentation,with a transitional regime(2.0-2.5 km/s)of partial melting.Spall strength decreases monotonically with temperature due to thermal softening.Elevated temperatures delay void nucleation but increase density,expanding spall regions and enhancing structural disorder with reduced BCC recovery.For microspallation,melting exacerbates damage,causing smaller voids and intensified atomic ejection,which increases with temperature.Free surface velocity profiles indicate damage:in classical spallation,first drop marks nucleation,and pullback signals spall layers.In micro-spallation,the first drop is irrelevant,but remains valid.Temperature delays pullback signals and weakens Hugoniot Elastic Limit.This study clarifies temperature-shock coupling in Ta spallation,aiding failure prediction in high-temperature shock environments.
基金funded by the Open Project Funding of Key Laboratory of Intelligent Health Perception and Ecological Restoration of Rivers and Lakes,Ministry of Education,Hubei University of Technology(HGKFYBP03)the Open Foundation of Resource-exhausted City Transformation and Development Research Center(Hubei Normal University)(KF2024Y07)the College Students'Innovative Entrepreneurial Training Plan Program(S202410513099,202410513009).
文摘Biological invasion is a pressing environmental and ecological challenge worldwide.Cabomba caroliniana(C.caroliniana),a submerged macrophyte native to South America,is listed as a high-priority invasive species in several countries.It is critical to understand how water temperature influences its invasiveness for effective management.However,research on the effects of water temperature on C.caroliniana the growth is limited.This study used controlled experiments to examine how water temperature(5-30℃)affects the morphological,physiological,photosynthetic,and stoichiometric traits of C.caroliniana.The results showed that broad water temperature tolerance of C.caroliniana significantly impacts its reproductive capacity and invasive potential.At 5-10℃,cold stress induced carotenoid synthesis and total organic carbon accumulation,enabling adaptation to low temperatures.However,C.caroliniana grew slowly,as its root development was limited,and its invasiveness remained low.At 20-30℃,increased chlorophyll synthesis and enhanced resource-use efficiency supported rapid growth,including more branches,leading to high invasion and dispersal potential.Thus,C.caroliniana exhibited strong colonization and spread quickly in tropical and subtropical waters(>20℃).In temperate zones,populations can be established during summer(20-25℃)and survive winter hrough cold adaptation.We recommended prioritizing control measures during warm seasons(20-30℃)to disrupt propagule dispersal,alongside early monitoring in temperate waters to inhibit ecological invasion.
