Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature c...Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature catalysts has become a current research focus.In this study,Nb was used to dope and modify the Mn_(7)-Cu_(3)/BCN catalyst to construct the Mn_(7)-Cu_(3)-Nb_(x)/BCN system.The doping amount was optimized through selective catalytic reduction(SCR)activity tests.The reaction mechanism was explored by combining in situ DRIFTS and density functional theory(DFT)simulations.Experimental findings revealed that the catalyst doped with 0.05%Nb achieved the optimal performance,sustaining a NO conversion efficiency of≥94%within the temperature window of 150−275℃while demonstrating improved resistance to alkali metal K poisoning.Mechanistic analyses showed that at low temperatures,the catalyst facilitated the SCR reaction via both the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)pathways,with the synergistic interaction between multiple active sites driving the efficient conversion of NH3 and NO.DFT calculations further confirmed that both pathways had the characteristics of low reaction energy barriers and significant exothermicity,ensuring the high activity and feasibility of the low-temperature reaction.The findings provided foundational theoretical support for the design of Nb-doped Mn-Cu-supported catalysts and the exploration of the underlying working mechanisms.展开更多
The paleo-geothermal gradient is a crucial parameter for converting the thermal history to the exhumation history.However,the precise estimation of this parameter has been a challenge.This paper presents a simple two-...The paleo-geothermal gradient is a crucial parameter for converting the thermal history to the exhumation history.However,the precise estimation of this parameter has been a challenge.This paper presents a simple two-step method to model the paleo-geothermal gradient using low-temperature thermochronology.(1)It uses the Monte Carlo approach to generate thermal histories in a vertical section randomly and calculates the entire thermal history within the goodnessof-fit thresholds based on different paleo-geothermal gradients.(2)It selects the optimum paleogeothermal gradient by comparing the entire thermal history within different goodness-of-fit thresholds.We validated the method with apatite(U-Th)/He and fission track data collected from two drill cores in the Haiyuan-Liupanshan region.The result revealed that the best-fit paleo-geothermal gradient was~42℃/km during the Early Cretaceous–Miocene and has decreased rapidly to 20℃/km since~10 Ma.The crust thickening in the study area may explain the rapid reduction in the paleogeothermal gradient since~10 Ma.Our results are consistent with earlier studies in the region,suggesting that our simple and more intuitive approach provides an alternative method for paleogeothermal gradient modeling.展开更多
In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study invest...In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study investigates the specific surface area,pore volume,structure complexity/connectivity,heterogeneity/local features of pore size distribution,and oxygen consumption dynamics of igneous metamorphic coal through N_(2)/CO_(2) isothermal adsorption tests and low-temperature oxidation experiments,and elucidates the influence mechanisms of pore structure evolution on oxygen consumption dynamics during low-temperature oxidation.With increasing metamorphic degree,igneous metamorphic coal exhibits a more pronounced reduction in specific surface area during oxidation,while the increase in structure complexity due to coal-oxygen reactions is suppressed.Thermally metamorphic coal demonstrates accelerated oxygen consumption,with oxidation amplifying the difference in reaction rates compared to raw coal.Key mechanisms include oxidation-induced reduction in mesopore complexity and micropore volume,decreased dominance of small-pore-volume apertures,and increased heterogeneity,collectively leading to a lower half-oxygen-consuming temperature and steeper oxygen consumption curves.Simultaneously,increased pore volume/complexity and reduced uniformity/connectivity act synergistically to enhance oxygen consumption capacity,highlighting the coupling between pore structure evolution and oxidation behavior in igneous metamorphic coal.This study provides theoretical insights into the pore-oxygen coupling mechanisms governing coal spontaneous combustion in igneous intrusion areas.展开更多
Lithium-ion batteries(LIBs),while dominant in energy storage due to high energy density and cycling stability,suffer from severe capacity decay,rate capability degradation,and lithium dendrite formation under low-temp...Lithium-ion batteries(LIBs),while dominant in energy storage due to high energy density and cycling stability,suffer from severe capacity decay,rate capability degradation,and lithium dendrite formation under low-temperature(LT)operation.Therefore,a more comprehensive and systematic understanding of LIB behavior at LT is urgently required.This review article comprehensively reviews recent advancements in electrolyte engineering strategies aimed at improving the low-temperature operational capabilities of LIBs.The study methodically examines critical performance-limiting mechanisms through fundamental analysis of four primary challenges:insufficient ionic conductivity under cryogenic conditions,kinetically hindered charge transfer processes,Li+transport limitations across the solidelectrolyte interphase(SEI),and uncontrolled lithium dendrite growth.The work elaborates on innovative optimization approaches encompassing lithium salt molecular design with tailored dissociation characteristics,solvent matrix optimization through dielectric constant and viscosity regulation,interfacial engineering additives for constructing low-impedance SEI layers,and gel-polymer composite electrolyte systems.Notably,particular emphasis is placed on emerging machine learning-guided electrolyte formulation strategies that enable high-throughput virtual screening of constituent combinations and prediction of structure-property relationships.These artificial intelligence-assisted rational design frameworks demonstrate significant potential for accelerating the development of next-generation LT electrolytes by establishing quantitative composition-performance correlations through advanced data-driven methodologies.展开更多
This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0...This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.展开更多
Objectives:Loneliness among left-behind adolescents is the most frequently reported emotional problem because of parental neglect.The present study explored the relationship between maternal absence and adolescent lon...Objectives:Loneliness among left-behind adolescents is the most frequently reported emotional problem because of parental neglect.The present study explored the relationship between maternal absence and adolescent loneliness as well as its mechanisms.Methods:The study included 305 participants(Meanage=15.99±0.81,48.9%females)in southeast China,and constructed a chain mediation model to test the roles of rejection sensitivity and friendship quality.Parent absence types,rejection sensitivity,friendship quality,and adolescent loneliness were all assessed with questionnaires.Results:The results showed that adolescents with a mother absent(both-parent absent,mother-only absent)experienced higher levels of loneliness than those with a mother not absent(father-only absent,non-parent absent)(β=0.3137,95%CI[0.0849,0.5425],p<0.01).Besides,the mediating roles of rejection sensitivity(β=0.0344,95%CI[0.0020,0.0808])and friendship quality(β=0.1198,95%CI[0.0049,0.2428])and their chain mediating role were found significant between maternal absence and loneliness(β=0.0245,95%CI[0.0015,0.0575]).Conclusions:These findings have revealed the significant impact of maternal absence on adolescent loneliness and provide important practical implications for educators to reduce adolescent loneliness.展开更多
Protons emerge as superior charge carriers due to the lowest mass-to-charge ratio,ultra-high natural abundance,and the smallest ionic radius.Herein,2.0 M H_(2) SO_(4) dissolved in EG(ethylene glycol)/H_(2)O cosolvent ...Protons emerge as superior charge carriers due to the lowest mass-to-charge ratio,ultra-high natural abundance,and the smallest ionic radius.Herein,2.0 M H_(2) SO_(4) dissolved in EG(ethylene glycol)/H_(2)O cosolvent is investigated as an aqueous proton battery electrolyte,which not only enhances the cycling performance of MoO_(3) nanorod anode but also improves its low-temperature electrochemical performance.Specifically,the EG tightly adsorbs onto the surface of MoO_(3) nanorods,thereby inhibiting the corrosion from H_(2)O molecules in the electrolyte and suppressing the dissolution of MoO_(3).In addition,EG molecule disturbs the hydrogen-bond network between H_(2)O molecules,which greatly decreases the freezing point of the electrolyte,endowing the MoO_(3) nanorods with excellent low-temperature electrochemical performance.Therefore,the MoO_(3) nanorods exhibit a capacity retention of 96.9%after 2000 cycles at a current density of 10 A g^(-1)in a three-electrode system.After assembling with CuHCF cathode,under-40℃,the full battery displays negligible capacity decay for over 2500 cycles at 1 A g^(-1).These results indicate that the cosolvent strategy has the promising potential in enhancing the performance of aqueous proton batteries.展开更多
[Objectives]This study aimed to evaluate the detection sensitivity of Staphylococcus aureus in dairy products utilizing the chip digital PCR(cdPCR)technique.[Methods]Specific primers and probes were designed and synth...[Objectives]This study aimed to evaluate the detection sensitivity of Staphylococcus aureus in dairy products utilizing the chip digital PCR(cdPCR)technique.[Methods]Specific primers and probes were designed and synthesized based on the conserved sequence of the heat-resistant nuclease gene nuc of S.aureus.cdPCR was employed to detect S.aureus,and the sensitivity of this technique was systematically assessed in samples exhibiting low levels of contamination.[Results]cdPCR demonstrated precise quantification when the initial concentration of the sample enrichment solution was equal to or greater than 50 CFU/mL.The detection dynamic range extended across at least five orders of magnitude,with a minimum DNA detection limit of 0.2304 pg/μL.In artificially contaminated cheese samples,the method s lower limit of quantification for detecting S.aureus was 8×10^(2) CFU/g.Regression analysis demonstrated that the gene copy number concentration measured by cdPCR exhibited a strong linear correlation with bacterial contamination concentration across a broad range.[Conclusions]The cdPCR method developed in this study demonstrates high sensitivity and robust quantitative capabilities,offering a reliable technical approach for the precise detection of low-level S.aureus contamination in dairy products.展开更多
In this study,the multi-scale(meso and macro)modelling was used to predict the electric response of the material.Porosity was introduced through a sugar-templating process to enhance compressibility and sensitivity.Me...In this study,the multi-scale(meso and macro)modelling was used to predict the electric response of the material.Porosity was introduced through a sugar-templating process to enhance compressibility and sensitivity.Mean-field homogenization was employed to predict the electrical conductivity of the nanocomposites,which was validated experimentally through I–V characterisation,confirming stable Ohmic behavior.The homogenised material parameters were incorporated into COMSOLMultiphysics to simulate diaphragmdeflection and capacitance variation under applied pressure.Experimental results showed a linear and stable capacitance response at the force magnitude of 0–7 N.The Graphene nanoplatelets(GnP)–Polydimethylsiloxane(PDMS)sensor demonstrated superior sensitivity(0.0032 pF/N)compared to the CNT–PDMS sensor(0.0019 pF/N),attributed to improved filler dispersion and higher effective surface area of GnP.Finite element simulations were further conducted to evaluate stress distribution in a GnP–PDMS-based capacitive sensor integrated into a shoe insole for gait analysis.The results correlated well with experimental capacitance changes,validating the sensor’s mechanical reliability and pressure sensitivity.This comparative study establishes the GnP–PDMS composite as a more effective candidate for low-cost,biocompatible,and high-performance flexible pressure sensors in wearable biomedical and gait monitoring applications.展开更多
Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorpo...Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorporates Weibull distributed heterogeneity to a single fracture in rock,and validate it against ceramic quenching and granite acoustic emission experiments.Distance based generalized sensitivity analysis(DGSA)is applied to quantify the influence and interactions of key parameters,revealing the dominant controls on spalling onset,severity,and damage morphology.The results demonstrate that thermal stress dominates crack initiation and propagation,that lateral constraints can significantly delay and suppress spalling,and that material heterogeneity markedly influences peak stress and damage modes within a certain range of thermal expansion coefficient and has multiple effects on thermal spalling.This study provides a theoretical basis for quantitative assessment and parameter optimization of thermal spalling processes in rock masses.展开更多
The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-effic...The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-efficiency excitation and detection elements may improve the imaging sensitivity to a certain extent,the application of the elements is inevitably subject to various limitations in practical applications,particularly during in vivo imaging and endoscopic imaging.In this study,we propose a multi-combinatorial approach to enhance the sensitivity of lipid photoacoustic imaging.The approach involves wavelet transform processing of one-dimensional A-line signals,gradient-based denoising of two-dimensional B-scan images,and finally,threedimensional spatial weighted averaging of the data processed by the previous two steps.This method not only significantly improves the signal-to-noise ratio(SNR)in distinguished feature regions of the image by around 10 dB,but also efficiently extracts weak signals with no distinct features in the original image.After processing with this method,the images acquired under single scanning were compared with those obtained under multiple scanning.The results showed highly consistent image features,with the structural similarity index increasing from 0.2 to 0.8,confirming the accuracy and reliability of the multi-combinatorial approach.展开更多
The Toraja Highlands,encompassing Tana Toraja and North Toraja,form the strategic upper reaches of the Saddang Watershed in South Sulawesi,where steep terrain,active land-cover change,and high ecological sensitivity c...The Toraja Highlands,encompassing Tana Toraja and North Toraja,form the strategic upper reaches of the Saddang Watershed in South Sulawesi,where steep terrain,active land-cover change,and high ecological sensitivity converge.This study addresses the need for an objective and validated ecological sensitivity map to support sustainable mountain watershed management.We construct an ecological sensitivity index based on principal component analysis using four key indicators:land cover,vegetation density(NDVI),slope,and rainfall,and evaluate its reliability through multi-source validation.Inputs integrate national elevation models,Landsat 8 imagery,and satellite-derived rainfall.Rainfall represents a multi-year climatology for 2015–2024,whereas land cover and NDVI reflect recent surface conditions derived from a cloud-free 2024 composite.The resulting sensitivity zonation indicates that 41.10%of Tana Toraja and 67.11%of North Toraja fall into the very high sensitivity class,concentrated on steep slopes and intensively converted landscapes.Eventbased spatial cross-validation against independent landslide records yields overall accuracies of 67.65%and 66.67%,while field verification produces Kappa values of 0.847 and 0.871.Stakeholder appraisal further corroborates the mapped patterns.Together,these convergent lines of evidence identify priority areas for reforestation,soil conservation,slope stabilization,and sustainable watershed management.The transparent and reproducible workflow supports evidence-based risk reduction and resilience building in the upper reaches of the Saddang Watershed.展开更多
This study investigates the influence of hydrogen concentration at grain boundaries on the sensitivity of polycrystalline iron to hydrogen embrittlement using molecular dynamics simulations.These simulations reveal th...This study investigates the influence of hydrogen concentration at grain boundaries on the sensitivity of polycrystalline iron to hydrogen embrittlement using molecular dynamics simulations.These simulations reveal the diffusion behavior of hydrogen atoms at grain boundaries and their consequential impact on the hydrogen embrittlement sensitivity of iron alloys.The findings indicate that as the hydrogen concentration increases,both the yield strength and ultimate tensile strength of Fe-H alloys exhibit a declining trend.Moreover,the capture of hydrogen atoms at the grain boundaries significantly influences the fracture toughness of the material and promotes the formation and propagation of cracks.This study provides a novel theoretical basis for understanding and predicting the hydrogen embrittlement behavior of iron-based materials in hydrogen-rich environments,offering valuable insights for the design and development of Fe alloys with enhanced resistance to hydrogen embrittlement.展开更多
As demand for land resources is rapidly growing nowadays,developing on slope lands has become a way to relieve pressure on flat lands.Although some studies use the concept of slope spectrum to explore the trend of lan...As demand for land resources is rapidly growing nowadays,developing on slope lands has become a way to relieve pressure on flat lands.Although some studies use the concept of slope spectrum to explore the trend of land use upslope,relying solely on the slope spectrum is too broad and prevents deeper research.Therefore,using China's land use and DEM data from 2000 to 2020,our study integrated the slope spectrum and the slope sensitivity coefficient(SSC)calculated by the land use transfer matrix as a new approach and method for understanding the underlying formations and impacts of upslope in farmland and construction land,supporting regional management strategies.The results show that:1)Farmlands were upslope in the South and developed horizontally in the North,and construction lands were upslope nationwide.2)Using the land use transfer matrix and SSC,we classified farmland upslope as passive and active patterns,and construction land upslope as saturation and avoidance patterns based on their land use transfer mechanisms in slope space.Provinces with passive and saturation patterns are mainly located near the east coast.3)Different patterns of upslope have distinct impacts on sustainable development.The passive pattern harms food security while the active pattern can relieve pressure on food security but increases ecological risks.Saturation pattern damages food security,ecological protection,and city livability,but avoidance pattern can promote food security and ecological protection.The findings will serve as an essential reference for developing land use strategies aimed at sustainable development.展开更多
The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solv...The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solvent-resistant Nitrate-coordinated electrolyte.The practical Ah-level graphite LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) pouch cell with the newly developed electrolyte demonstrates a significant breakthrough in cycling stability,exhibiting negligible capacity fade after 250 cycles at-30℃ and 0.1 C.NO_(3)^(-),as the functional additive,compresses the electric field around Li^(+)through electrostatic interactions,mimicking the Debye-screening effect and inducing the coordinative exclusion of free ethyl acetate molecules at low temperatures.The transformation from contact ion pairs(CIPs)formed by Pto solventseparated ion pairs is significantly restrained,which mitigates the continuous reactions between the electrolyte and inevitable lithium deposition at low temperature.Additionally,this customized inert CIPs form a solid electrolyte interphase on graphite that exhibits remarkable ionic conductivity and rigidity,preventing excessive Li dendrite growth.This finding offers new insights into the relationship of microstructure-performance for low-temperature electrolytes,demonstrating that relying solely on inert CIPs can also inhibit the decomposition of the interfacial electrolyte,and inspires a unique design concept for high-performance,commercially viable LIBs that operate reliably in sub-zero environments.展开更多
The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant ...The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant feedlines.The dynamic characteristics of valve-closing water hammer and filling water hammer are investigated by this method,and the sensitivity of filling water hammer is analyzed with a single factor sensitivity analysis with 8 factors and 9 levels and a multi-factor sensitivity analysis with L_(27)(3^(13))orthogonal experiment based on range method.It is found that the solving result of LBM with entropy limiter is basically in good agreement with finite volume method,and using the entropy limiter can eliminate numerical oscillations when solving valve-closing water hammer problems and solve the numerical"blow up"when solving filling water hammer problems.It can be seen that the dynamic characteristics of valve-closing water hammer are relatively simple,while there are many factors that affect the filling water hammer and the degree of these effects varies.The effects on the maximum water hammer pressure are relatively uniform,but those on the water hammer response time vary greatly through the skewness analysis.展开更多
Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant paramete...Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant parameters.To address this challenge,we develop a simulation model of the Taiji scientific interferometer,generating noise datasets under multiparameter conditions.Given the uniqueness of the telescope as well as the convergence behavior of the algorithm,the analysis is structured hierarchically:(i)the telescope level and(ii)the optical bench level.A hierarchical framework combining XGBoost and SHapley Additive exPlanations(SHAP)values is employed to model the intricate relationships between parameters and TTL coupling noise,supplemented by sensitivity analysis.Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level,while the angles of the plane mirrors and beam splitters are most influential at the optical bench level.The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy.This approach offers actionable insights for optimizing the Taiji interferometer design.展开更多
This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation m...This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation method(DDM)with the linear multibody system transfer matrix method(linear MSTMM).The rigid-flexible coupled multibody system dynamics model of a tracked vehicle is established using the linear MSTMM and validated through the modal test.Building upon the existing DDM-based eigenvalue sensitivity analysis method within the linear MSTMM,the DDM is embedded into it to enable programmable and efficient computation of dynamic response sensitivities for mechanical systems.The proposed approach is used to quantitatively evaluate the sensitivities of both natural vibration characteristics(e.g.,natural frequencies and mode shapes)and transient dynamic responses of the tracked vehicle with respect to system parameters,successfully identifying critical structural parameters.Compared to conventional finite difference methods,the developed methodology eliminates sensitivity to perturbation step sizes.The contributions of this work lie in establishing a unified theoretical foundation and analysis framework for guiding dynamics optimization and design of mechanical systems,and extending the applicability of the linear MSTMM to sensitivity analysis of transient dynamic responses.展开更多
To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) po...To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.展开更多
基金Supported by National Key Research and Development Program of China(2020YFD1100302)。
文摘Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature catalysts has become a current research focus.In this study,Nb was used to dope and modify the Mn_(7)-Cu_(3)/BCN catalyst to construct the Mn_(7)-Cu_(3)-Nb_(x)/BCN system.The doping amount was optimized through selective catalytic reduction(SCR)activity tests.The reaction mechanism was explored by combining in situ DRIFTS and density functional theory(DFT)simulations.Experimental findings revealed that the catalyst doped with 0.05%Nb achieved the optimal performance,sustaining a NO conversion efficiency of≥94%within the temperature window of 150−275℃while demonstrating improved resistance to alkali metal K poisoning.Mechanistic analyses showed that at low temperatures,the catalyst facilitated the SCR reaction via both the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)pathways,with the synergistic interaction between multiple active sites driving the efficient conversion of NH3 and NO.DFT calculations further confirmed that both pathways had the characteristics of low reaction energy barriers and significant exothermicity,ensuring the high activity and feasibility of the low-temperature reaction.The findings provided foundational theoretical support for the design of Nb-doped Mn-Cu-supported catalysts and the exploration of the underlying working mechanisms.
基金supported by the National Natural Science Foundation of China(Nos.42072229,42030301,41102131,41972049,41972302 and 41977231)the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515010724)+3 种基金the Guangdong Natural Science Foundation(No.2021A1515011658)the Science and Technology Program of Guangzhou(No.202002030184)the Special Fund for Basic Scientific Research of Central Colleges,Chang'an University(No.300102260502)the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(No.2024ZD1001003)。
文摘The paleo-geothermal gradient is a crucial parameter for converting the thermal history to the exhumation history.However,the precise estimation of this parameter has been a challenge.This paper presents a simple two-step method to model the paleo-geothermal gradient using low-temperature thermochronology.(1)It uses the Monte Carlo approach to generate thermal histories in a vertical section randomly and calculates the entire thermal history within the goodnessof-fit thresholds based on different paleo-geothermal gradients.(2)It selects the optimum paleogeothermal gradient by comparing the entire thermal history within different goodness-of-fit thresholds.We validated the method with apatite(U-Th)/He and fission track data collected from two drill cores in the Haiyuan-Liupanshan region.The result revealed that the best-fit paleo-geothermal gradient was~42℃/km during the Early Cretaceous–Miocene and has decreased rapidly to 20℃/km since~10 Ma.The crust thickening in the study area may explain the rapid reduction in the paleogeothermal gradient since~10 Ma.Our results are consistent with earlier studies in the region,suggesting that our simple and more intuitive approach provides an alternative method for paleogeothermal gradient modeling.
基金supported by the National Natural Science Foundation of China(No.52374247)the Joint Funds of the National Natural Science Foundation of China(No.U24B2042).
文摘In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study investigates the specific surface area,pore volume,structure complexity/connectivity,heterogeneity/local features of pore size distribution,and oxygen consumption dynamics of igneous metamorphic coal through N_(2)/CO_(2) isothermal adsorption tests and low-temperature oxidation experiments,and elucidates the influence mechanisms of pore structure evolution on oxygen consumption dynamics during low-temperature oxidation.With increasing metamorphic degree,igneous metamorphic coal exhibits a more pronounced reduction in specific surface area during oxidation,while the increase in structure complexity due to coal-oxygen reactions is suppressed.Thermally metamorphic coal demonstrates accelerated oxygen consumption,with oxidation amplifying the difference in reaction rates compared to raw coal.Key mechanisms include oxidation-induced reduction in mesopore complexity and micropore volume,decreased dominance of small-pore-volume apertures,and increased heterogeneity,collectively leading to a lower half-oxygen-consuming temperature and steeper oxygen consumption curves.Simultaneously,increased pore volume/complexity and reduced uniformity/connectivity act synergistically to enhance oxygen consumption capacity,highlighting the coupling between pore structure evolution and oxidation behavior in igneous metamorphic coal.This study provides theoretical insights into the pore-oxygen coupling mechanisms governing coal spontaneous combustion in igneous intrusion areas.
基金the financial support from the Key Project of Shaanxi Provincial Natural Science Foundation-Key Project of Laboratory(2025SYS-SYSZD-117)the Natural Science Basic Research Program of Shaanxi(2025JCYBQN-125)+8 种基金Young Talent Fund of Xi'an Association for Science and Technology(0959202513002)the Key Industrial Chain Technology Research Program of Xi'an(24ZDCYJSGG0048)the Key Research and Development Program of Xianyang(L2023-ZDYF-SF-077)Postdoctoral Fellowship Program of CPSF(GZC20241442)Shaanxi Postdoctoral Science Foundation(2024BSHSDZZ070)Research Funds for the Interdisciplinary Projects,CHU(300104240913)the Fundamental Research Funds for the Central Universities,CHU(300102385739,300102384201,300102384103)the Scientific Innovation Practice Project of Postgraduate of Chang'an University(300103725063)the financial support from the Australian Research Council。
文摘Lithium-ion batteries(LIBs),while dominant in energy storage due to high energy density and cycling stability,suffer from severe capacity decay,rate capability degradation,and lithium dendrite formation under low-temperature(LT)operation.Therefore,a more comprehensive and systematic understanding of LIB behavior at LT is urgently required.This review article comprehensively reviews recent advancements in electrolyte engineering strategies aimed at improving the low-temperature operational capabilities of LIBs.The study methodically examines critical performance-limiting mechanisms through fundamental analysis of four primary challenges:insufficient ionic conductivity under cryogenic conditions,kinetically hindered charge transfer processes,Li+transport limitations across the solidelectrolyte interphase(SEI),and uncontrolled lithium dendrite growth.The work elaborates on innovative optimization approaches encompassing lithium salt molecular design with tailored dissociation characteristics,solvent matrix optimization through dielectric constant and viscosity regulation,interfacial engineering additives for constructing low-impedance SEI layers,and gel-polymer composite electrolyte systems.Notably,particular emphasis is placed on emerging machine learning-guided electrolyte formulation strategies that enable high-throughput virtual screening of constituent combinations and prediction of structure-property relationships.These artificial intelligence-assisted rational design frameworks demonstrate significant potential for accelerating the development of next-generation LT electrolytes by establishing quantitative composition-performance correlations through advanced data-driven methodologies.
基金financially supported by the National Natural Science Foundation of China(No.22309067)the Open Project Program of the State Key Laboratory of Materials-Oriented Chemical Engineering,China(No.KL21-05)the Marine Equipment and Technology Institute,Jiangsu University of Science and Technology,China(No.XTCX202404)。
文摘This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.
基金supported by the National Natural Science Foundation of China(32171069).
文摘Objectives:Loneliness among left-behind adolescents is the most frequently reported emotional problem because of parental neglect.The present study explored the relationship between maternal absence and adolescent loneliness as well as its mechanisms.Methods:The study included 305 participants(Meanage=15.99±0.81,48.9%females)in southeast China,and constructed a chain mediation model to test the roles of rejection sensitivity and friendship quality.Parent absence types,rejection sensitivity,friendship quality,and adolescent loneliness were all assessed with questionnaires.Results:The results showed that adolescents with a mother absent(both-parent absent,mother-only absent)experienced higher levels of loneliness than those with a mother not absent(father-only absent,non-parent absent)(β=0.3137,95%CI[0.0849,0.5425],p<0.01).Besides,the mediating roles of rejection sensitivity(β=0.0344,95%CI[0.0020,0.0808])and friendship quality(β=0.1198,95%CI[0.0049,0.2428])and their chain mediating role were found significant between maternal absence and loneliness(β=0.0245,95%CI[0.0015,0.0575]).Conclusions:These findings have revealed the significant impact of maternal absence on adolescent loneliness and provide important practical implications for educators to reduce adolescent loneliness.
基金supported by the National Natural Science Foundation of China(22409071)Natural Foundation of Shandong Province(ZR2024QB120)+2 种基金Youth Innovation Group Plan of Shandong Province(2024KJG046)Higher-Level Talent Initial Scientific Research and Discipline Construction Fund(511/1009530)Joint Funds of the National Natural Science Foundation of China(No.U22A20140)。
文摘Protons emerge as superior charge carriers due to the lowest mass-to-charge ratio,ultra-high natural abundance,and the smallest ionic radius.Herein,2.0 M H_(2) SO_(4) dissolved in EG(ethylene glycol)/H_(2)O cosolvent is investigated as an aqueous proton battery electrolyte,which not only enhances the cycling performance of MoO_(3) nanorod anode but also improves its low-temperature electrochemical performance.Specifically,the EG tightly adsorbs onto the surface of MoO_(3) nanorods,thereby inhibiting the corrosion from H_(2)O molecules in the electrolyte and suppressing the dissolution of MoO_(3).In addition,EG molecule disturbs the hydrogen-bond network between H_(2)O molecules,which greatly decreases the freezing point of the electrolyte,endowing the MoO_(3) nanorods with excellent low-temperature electrochemical performance.Therefore,the MoO_(3) nanorods exhibit a capacity retention of 96.9%after 2000 cycles at a current density of 10 A g^(-1)in a three-electrode system.After assembling with CuHCF cathode,under-40℃,the full battery displays negligible capacity decay for over 2500 cycles at 1 A g^(-1).These results indicate that the cosolvent strategy has the promising potential in enhancing the performance of aqueous proton batteries.
基金Supported by Science and Technology Program of Inner Mongolia Autonomous Region"Research and Demonstration of Novel Molecular Biological Identification Technology for Multiple Source Components in Milk and Dairy Products"(2025YFSH0029).
文摘[Objectives]This study aimed to evaluate the detection sensitivity of Staphylococcus aureus in dairy products utilizing the chip digital PCR(cdPCR)technique.[Methods]Specific primers and probes were designed and synthesized based on the conserved sequence of the heat-resistant nuclease gene nuc of S.aureus.cdPCR was employed to detect S.aureus,and the sensitivity of this technique was systematically assessed in samples exhibiting low levels of contamination.[Results]cdPCR demonstrated precise quantification when the initial concentration of the sample enrichment solution was equal to or greater than 50 CFU/mL.The detection dynamic range extended across at least five orders of magnitude,with a minimum DNA detection limit of 0.2304 pg/μL.In artificially contaminated cheese samples,the method s lower limit of quantification for detecting S.aureus was 8×10^(2) CFU/g.Regression analysis demonstrated that the gene copy number concentration measured by cdPCR exhibited a strong linear correlation with bacterial contamination concentration across a broad range.[Conclusions]The cdPCR method developed in this study demonstrates high sensitivity and robust quantitative capabilities,offering a reliable technical approach for the precise detection of low-level S.aureus contamination in dairy products.
文摘In this study,the multi-scale(meso and macro)modelling was used to predict the electric response of the material.Porosity was introduced through a sugar-templating process to enhance compressibility and sensitivity.Mean-field homogenization was employed to predict the electrical conductivity of the nanocomposites,which was validated experimentally through I–V characterisation,confirming stable Ohmic behavior.The homogenised material parameters were incorporated into COMSOLMultiphysics to simulate diaphragmdeflection and capacitance variation under applied pressure.Experimental results showed a linear and stable capacitance response at the force magnitude of 0–7 N.The Graphene nanoplatelets(GnP)–Polydimethylsiloxane(PDMS)sensor demonstrated superior sensitivity(0.0032 pF/N)compared to the CNT–PDMS sensor(0.0019 pF/N),attributed to improved filler dispersion and higher effective surface area of GnP.Finite element simulations were further conducted to evaluate stress distribution in a GnP–PDMS-based capacitive sensor integrated into a shoe insole for gait analysis.The results correlated well with experimental capacitance changes,validating the sensor’s mechanical reliability and pressure sensitivity.This comparative study establishes the GnP–PDMS composite as a more effective candidate for low-cost,biocompatible,and high-performance flexible pressure sensors in wearable biomedical and gait monitoring applications.
基金funded by the National Natural Science Foundation of China(Nos.52574100,52574001,and 52311530070)the Major National Science and Technology Project for Deep Earth of China(No.2024ZD1003805)+1 种基金the Fundamental Research Funds for the Central Universities of China(No.FRF-IDRY-20-003,Interdisciplinary Research Project for Young Teachers of USTB)DE gratefully acknowledges support from the G.Albert Shoemaker endowment.
文摘Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorporates Weibull distributed heterogeneity to a single fracture in rock,and validate it against ceramic quenching and granite acoustic emission experiments.Distance based generalized sensitivity analysis(DGSA)is applied to quantify the influence and interactions of key parameters,revealing the dominant controls on spalling onset,severity,and damage morphology.The results demonstrate that thermal stress dominates crack initiation and propagation,that lateral constraints can significantly delay and suppress spalling,and that material heterogeneity markedly influences peak stress and damage modes within a certain range of thermal expansion coefficient and has multiple effects on thermal spalling.This study provides a theoretical basis for quantitative assessment and parameter optimization of thermal spalling processes in rock masses.
基金supported by the National Key Research and Development Program of China(2022YFC2402400)the National Natural Science Foundation of China(82027803,62275062)+7 种基金the Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology(2020B121201010)the Shenzhen Science and Technology Innovation Committee under Grant(JCYJ20220818101417039)the Shenzhen Key Laboratory for Molecular lmaging(ZDSY20130401165820357)the Shenzhen Medical Research Fund(D2404002)the Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments(2023-SGTTXM-002 and 2024-SGTTXM-005)the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)(YDZX2023115)the Taishan Scholar Special Funding Project of Shandong Provinceand the Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai(ZL202402).
文摘The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-efficiency excitation and detection elements may improve the imaging sensitivity to a certain extent,the application of the elements is inevitably subject to various limitations in practical applications,particularly during in vivo imaging and endoscopic imaging.In this study,we propose a multi-combinatorial approach to enhance the sensitivity of lipid photoacoustic imaging.The approach involves wavelet transform processing of one-dimensional A-line signals,gradient-based denoising of two-dimensional B-scan images,and finally,threedimensional spatial weighted averaging of the data processed by the previous two steps.This method not only significantly improves the signal-to-noise ratio(SNR)in distinguished feature regions of the image by around 10 dB,but also efficiently extracts weak signals with no distinct features in the original image.After processing with this method,the images acquired under single scanning were compared with those obtained under multiple scanning.The results showed highly consistent image features,with the structural similarity index increasing from 0.2 to 0.8,confirming the accuracy and reliability of the multi-combinatorial approach.
基金funded by the Ministry of Higher Education,Science and Technology,Republic of Indonesia through the Indonesia Collaborative Research(Riset Kolaborasi Indonesia)grant(Number:01319/UN4.22/PT.01.03/2025)。
文摘The Toraja Highlands,encompassing Tana Toraja and North Toraja,form the strategic upper reaches of the Saddang Watershed in South Sulawesi,where steep terrain,active land-cover change,and high ecological sensitivity converge.This study addresses the need for an objective and validated ecological sensitivity map to support sustainable mountain watershed management.We construct an ecological sensitivity index based on principal component analysis using four key indicators:land cover,vegetation density(NDVI),slope,and rainfall,and evaluate its reliability through multi-source validation.Inputs integrate national elevation models,Landsat 8 imagery,and satellite-derived rainfall.Rainfall represents a multi-year climatology for 2015–2024,whereas land cover and NDVI reflect recent surface conditions derived from a cloud-free 2024 composite.The resulting sensitivity zonation indicates that 41.10%of Tana Toraja and 67.11%of North Toraja fall into the very high sensitivity class,concentrated on steep slopes and intensively converted landscapes.Eventbased spatial cross-validation against independent landslide records yields overall accuracies of 67.65%and 66.67%,while field verification produces Kappa values of 0.847 and 0.871.Stakeholder appraisal further corroborates the mapped patterns.Together,these convergent lines of evidence identify priority areas for reforestation,soil conservation,slope stabilization,and sustainable watershed management.The transparent and reproducible workflow supports evidence-based risk reduction and resilience building in the upper reaches of the Saddang Watershed.
基金supported by the National Science Fund for Distinguished Young Scholars(No.52425404).
文摘This study investigates the influence of hydrogen concentration at grain boundaries on the sensitivity of polycrystalline iron to hydrogen embrittlement using molecular dynamics simulations.These simulations reveal the diffusion behavior of hydrogen atoms at grain boundaries and their consequential impact on the hydrogen embrittlement sensitivity of iron alloys.The findings indicate that as the hydrogen concentration increases,both the yield strength and ultimate tensile strength of Fe-H alloys exhibit a declining trend.Moreover,the capture of hydrogen atoms at the grain boundaries significantly influences the fracture toughness of the material and promotes the formation and propagation of cracks.This study provides a novel theoretical basis for understanding and predicting the hydrogen embrittlement behavior of iron-based materials in hydrogen-rich environments,offering valuable insights for the design and development of Fe alloys with enhanced resistance to hydrogen embrittlement.
基金funded by the National Natural Science Foundation of China(Grant No.72504262)Natural Science Foundation of Hubei Province of China(Grant No.2024AFB102)。
文摘As demand for land resources is rapidly growing nowadays,developing on slope lands has become a way to relieve pressure on flat lands.Although some studies use the concept of slope spectrum to explore the trend of land use upslope,relying solely on the slope spectrum is too broad and prevents deeper research.Therefore,using China's land use and DEM data from 2000 to 2020,our study integrated the slope spectrum and the slope sensitivity coefficient(SSC)calculated by the land use transfer matrix as a new approach and method for understanding the underlying formations and impacts of upslope in farmland and construction land,supporting regional management strategies.The results show that:1)Farmlands were upslope in the South and developed horizontally in the North,and construction lands were upslope nationwide.2)Using the land use transfer matrix and SSC,we classified farmland upslope as passive and active patterns,and construction land upslope as saturation and avoidance patterns based on their land use transfer mechanisms in slope space.Provinces with passive and saturation patterns are mainly located near the east coast.3)Different patterns of upslope have distinct impacts on sustainable development.The passive pattern harms food security while the active pattern can relieve pressure on food security but increases ecological risks.Saturation pattern damages food security,ecological protection,and city livability,but avoidance pattern can promote food security and ecological protection.The findings will serve as an essential reference for developing land use strategies aimed at sustainable development.
基金support from the Heilongjiang Touyan Innovation Team Program(HITTY-20190033)National Natural Science Foundation of China(22278096)Innovation Special Project on Science and Technology for Carbon Peaking and Carbon Neutrality in Jiangsu Province(WSSJH20230015)。
文摘The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solvent-resistant Nitrate-coordinated electrolyte.The practical Ah-level graphite LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) pouch cell with the newly developed electrolyte demonstrates a significant breakthrough in cycling stability,exhibiting negligible capacity fade after 250 cycles at-30℃ and 0.1 C.NO_(3)^(-),as the functional additive,compresses the electric field around Li^(+)through electrostatic interactions,mimicking the Debye-screening effect and inducing the coordinative exclusion of free ethyl acetate molecules at low temperatures.The transformation from contact ion pairs(CIPs)formed by Pto solventseparated ion pairs is significantly restrained,which mitigates the continuous reactions between the electrolyte and inevitable lithium deposition at low temperature.Additionally,this customized inert CIPs form a solid electrolyte interphase on graphite that exhibits remarkable ionic conductivity and rigidity,preventing excessive Li dendrite growth.This finding offers new insights into the relationship of microstructure-performance for low-temperature electrolytes,demonstrating that relying solely on inert CIPs can also inhibit the decomposition of the interfacial electrolyte,and inspires a unique design concept for high-performance,commercially viable LIBs that operate reliably in sub-zero environments.
基金supported by the Natural Science BasicResearch Program of Shaanxi,China(No.2021JC-14)。
文摘The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant feedlines.The dynamic characteristics of valve-closing water hammer and filling water hammer are investigated by this method,and the sensitivity of filling water hammer is analyzed with a single factor sensitivity analysis with 8 factors and 9 levels and a multi-factor sensitivity analysis with L_(27)(3^(13))orthogonal experiment based on range method.It is found that the solving result of LBM with entropy limiter is basically in good agreement with finite volume method,and using the entropy limiter can eliminate numerical oscillations when solving valve-closing water hammer problems and solve the numerical"blow up"when solving filling water hammer problems.It can be seen that the dynamic characteristics of valve-closing water hammer are relatively simple,while there are many factors that affect the filling water hammer and the degree of these effects varies.The effects on the maximum water hammer pressure are relatively uniform,but those on the water hammer response time vary greatly through the skewness analysis.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFC2200100)the CAS's Strategic Pioneer Program on Space Science(Grant No.XDA1502110201)。
文摘Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant parameters.To address this challenge,we develop a simulation model of the Taiji scientific interferometer,generating noise datasets under multiparameter conditions.Given the uniqueness of the telescope as well as the convergence behavior of the algorithm,the analysis is structured hierarchically:(i)the telescope level and(ii)the optical bench level.A hierarchical framework combining XGBoost and SHapley Additive exPlanations(SHAP)values is employed to model the intricate relationships between parameters and TTL coupling noise,supplemented by sensitivity analysis.Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level,while the angles of the plane mirrors and beam splitters are most influential at the optical bench level.The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy.This approach offers actionable insights for optimizing the Taiji interferometer design.
基金supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20241443)the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2024ZB072)the National Natural Science Foundation of China(Grant No.92266201).
文摘This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation method(DDM)with the linear multibody system transfer matrix method(linear MSTMM).The rigid-flexible coupled multibody system dynamics model of a tracked vehicle is established using the linear MSTMM and validated through the modal test.Building upon the existing DDM-based eigenvalue sensitivity analysis method within the linear MSTMM,the DDM is embedded into it to enable programmable and efficient computation of dynamic response sensitivities for mechanical systems.The proposed approach is used to quantitatively evaluate the sensitivities of both natural vibration characteristics(e.g.,natural frequencies and mode shapes)and transient dynamic responses of the tracked vehicle with respect to system parameters,successfully identifying critical structural parameters.Compared to conventional finite difference methods,the developed methodology eliminates sensitivity to perturbation step sizes.The contributions of this work lie in establishing a unified theoretical foundation and analysis framework for guiding dynamics optimization and design of mechanical systems,and extending the applicability of the linear MSTMM to sensitivity analysis of transient dynamic responses.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2020B1111360003)the National Natural Science Foundation of China(Nos.42465008 and 42105164)+2 种基金Yunnan Science and Technology Department Project(No.202501AT070239)Yunnan Science and Technology Department Youth Project(No.202401AU070202)Xianyang Rapid Response Decision Support Project for Ozone(No.YZ2024-ZB019).
文摘To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.
