Battery technology plays a crucial role across various sectors,powering devices from smartphones to electric vehicles and supporting grid-scale energy storage.To ensure their safety and efficiency,batteries must be ev...Battery technology plays a crucial role across various sectors,powering devices from smartphones to electric vehicles and supporting grid-scale energy storage.To ensure their safety and efficiency,batteries must be evaluated under diverse operating conditions.Traditional modeling techniques,which often rely on first principles and atomic-level calculations,struggle with practical applications due to incomplete or noisy data.Furthermore,the complexity of battery dynamics,shaped by physical,chemical,and electrochemical interactions,presents substantial challenges for precise and efficient modeling.The Transformer model,originally designed for natural language processing,has proven effective in time-series analysis and forecasting.It adeptly handles the extensive,complex datasets produced during battery cycles,efficiently filtering out noise and identifying critical features without extensive preprocessing.This capability positions Transformers as potent tools for tackling the intricacies of battery data.This review explores the application of customized Transformers in battery state estimation,emphasizing crucial aspects such as charging,health assessment,lifetime prediction,and safety monitoring.It highlights the distinct advantages of Transformer-based models and addresses ongoing challenges and future opportunities in the field.By combining data-driven AI techniques with empirical insights from battery analysis,these pre-trained models can deliver precise diagnostics and comprehensive monitoring,enhancing performance metrics like health monitoring,anomaly detection,and early-warning systems.This integrated approach promises significant improvements in battery technology management and application.展开更多
Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell paramet...Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.展开更多
Objective:To understand the current status and changing trends in the lifetime risk of residents in Henan Province,China to develop and die from cancer.Methods:Lifetime risk was estimated using the Adjusted for Multip...Objective:To understand the current status and changing trends in the lifetime risk of residents in Henan Province,China to develop and die from cancer.Methods:Lifetime risk was estimated using the Adjusted for Multiple Primaries(AMP)method,incorporating cancer incidence,mortality,and all-cause mortality data from 55 cancer registries in Henan Province,China.Estimates were calculated overall and stratified by gender and area.The annual percent change(APC)in lifetime risk from 2010 to 2020,stratified by gender and cancer site,was estimated using a log-linear model.Results:In 2020,the lifetime risk of developing and dying from cancer was 30.19%(95%CI:29.63%-30.76%)and 23.62%(95%CI:23.28%-23.95%),respectively.These estimates were higher in men,with values of 31.22%(95%CI:30.59%-31.85%)for developing cancer and 26.73%(95%CI:26.29%-27.16%)for dying from cancer,compared with women,who had values of 29.02%(95%CI:28.12%-29.91%)and 20.08%(95%CI:19.51%-20.64%),respectively.There were also geographical differences,with higher estimates in urban areas compared with rural areas.Residents had the highest lifetime risk of developing lung cancer,with a rate of 6.94%,followed by breast cancer(4.14%),stomach cancer(3.95%),esophageal cancer(3.75%),and liver cancer(2.86%).Similarly,the highest lifetime risk of dying from cancer was observed for the following sites:lung(5.99%),stomach(3.60%),esophagus(3.39%),liver(2.78%),and colorectum(1.55%).Overall,the lifetime risk of developing cancer increased,with an APC of 0.75%(P<0.05).Varying trends were observed across different cancer sites.There were gradual decreases in nasopharynx,esophagus,stomach,and liver cancers.Conversely,increasing trends were noted for most other sites,with the highest APCs observed in thyroid,prostate,lymphoma,kidney,and gallbladder cancers.Conclusion:The lifetime risks of developing and dying from cancer were 30.19%and 23.62%,respectively.Variations in cancer risk across different regions,genders,specific cancer sites,and over calendar years provide important information for cancer prevention and policy making in the population.展开更多
In order to accurately evaluate the creep-fatigue lifetime of GH720Li superalloy,a lifetime prediction model was established,reflecting the interaction between creep damage and low-cycle fatigue damage.The creep-fatig...In order to accurately evaluate the creep-fatigue lifetime of GH720Li superalloy,a lifetime prediction model was established,reflecting the interaction between creep damage and low-cycle fatigue damage.The creep-fatigue lifetime prediction results of GH720Li superalloy with an average grain size of 17.3μm were essentially within a scatter band of 2 times,indicating a strong agreement between the predicted lifetimes and experimental data.Then,considering that the grain size of the dual-property turbine disc decreases from the rim to the center,a grain-size-sensitive lifetime prediction model for creep-fatigue was established by introducing the ratio of grain boundary area.The improved model overcame the limitation of most traditional prediction methods,which failed to reflect the relationship between grain size and creep-fatigue lifetime.展开更多
Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions.Owing to the nondestructive ion detection features of S...Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions.Owing to the nondestructive ion detection features of Schottky noise detectors,the number of stored ions in the ring is determined by the peak area in the measured revolution frequency spectrum.Because of their intrinsic amplitude-frequency characteristic(AFC),Schottky detector systems exhibit varying sensitivities at different frequencies.Using low-energy electron-cooled stored ions,a new method is developed to calibrate the AFC curve of the Schottky detector system of the Experimental Cooler Storage Ring(CSRe)storage ring located in Lanzhou,China.Using the amplitude-calibrated frequency spectrum,a notable refinement was observed in the precision of both the peak position and peak area.As a result,the storage lifetimes of the electron-cooled fully ionized^(56)Fe^(26+)ions were determined with high precision at beam energies of 13.7 and 116.4 MeV/u,despite of frequency drifts during the experiment.When electron cooling was turned off,the effective vacuum condition experienced by the 116.4 MeV/u^(56)Fe^(26+)ions was determined using amplitude-calibrated spectra,revealing a value of 2×10^(−10)mbar,which is consistent with vacuum gauge readings along the CSRe ring.The method reported herein will be adapted for the next-generation storage ring of the HIAF facility under construction in Huizhou,China.It can also be adapted to other storage ring facilities worldwide to improve precision and enhance lifetime measurements using many ions in the ring.展开更多
Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LED...Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LEDs[7,8].However,it took much longer time for GaN-based LDs to achieve high power,high wall plug efficiency,and long lifetime.Until 2019,Nichia reported blue LDs with these performances[9],which open wide applications with GaN-based blue LDs.展开更多
A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H...A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H-SiC epilayer by reducing carbon vacancies. However, this process also generates carbon clusters with limited diffusivity and contributes to the enlargement of surface pits on the 4H-SiC. High-temperature hydrogen annealing effectively reduces stacking fault and dislocation density. Moreover, electron spin resonance analysis indicates a significant reduction in carbon vacancy defects after hydrogen annealing. The mechanisms of the elimination of carbon vacancies by hydrogen annealing include the decomposition of carbon clusters formed during thermal oxidation and the low-pressure selective etching by hydrogen,which increases the carbon content on the 4H-SiC surface and facilitates carbon diffusion. Consequently, the combination of thermal oxidation and hydrogen annealing eliminates carbon vacancies more effectively, substantially enhancing the minority carrier lifetime in P-type 4H-SiC. This improvement is advantageous for the application of high-voltage SiC bipolar devices.展开更多
Minority carrier lifetimesτare a fundamental parameter in semiconductor devices,representing the average time it takes for excess minority carriers to recombine.This characteristic is crucial for understanding and op...Minority carrier lifetimesτare a fundamental parameter in semiconductor devices,representing the average time it takes for excess minority carriers to recombine.This characteristic is crucial for understanding and optimizing the performance of semiconductor materials,as it directly influences charge carrier dynamics and overall device efficiency.This work presents a development of PbS thin film deposited by thermal evaporation,at which the PbS thin film was further employed for structural,optical properties,andτ.Especially,the PbS film is probed with an in-house setup for identifying theτ.The procedure is to subject the PbS thin film with a flashlight from a light source with a middle rotating frequency.The derivedτin the in-house characterization setup agrees well with the value from the higher cost characterizing approach of photoluminescence.Therefore,the in-house setup provides additional tools for identifying theτvalues for semiconductor devices.展开更多
The widespread usage of rechargeable batteries in portable devices,electric vehicles,and energy storage systems has underscored the importance for accurately predicting their lifetimes.However,data scarcity often limi...The widespread usage of rechargeable batteries in portable devices,electric vehicles,and energy storage systems has underscored the importance for accurately predicting their lifetimes.However,data scarcity often limits the accuracy of prediction models,which is escalated by the incompletion of data induced by the issues such as sensor failures.To address these challenges,we propose a novel approach to accommodate data insufficiency through achieving external information from incomplete data samples,which are usually discarded in existing studies.In order to fully unleash the prediction power of incomplete data,we have investigated the Multiple Imputation by Chained Equations(MICE)method that diversifies the training data through exploring the potential data patterns.The experimental results demonstrate that the proposed method significantly outperforms the baselines in the most considered scenarios while reducing the prediction root mean square error(RMSE)by up to 18.9%.Furthermore,we have also observed that the penetration of incomplete data benefits the explainability of the prediction model through facilitating the feature selection.展开更多
We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the un...We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the unit speed. The models, without or with immigration, are constructed as measure-valued processes by pathwise unique solutions of stochastic equations driven by time-space Poisson random measures. In the subcritical branching case, we give a sufficient condition for the ergodicity of the process with immigration. Two large number laws and a central limit theorem of the occupation times are proved.展开更多
Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polym...Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polymers exhibit a short RTP lifetime(<1 s)because of their unstable triplet excitons.Herein,a new strategy of polymer chain stabilized phosphorescence(PCSP),which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response,has been reported.The rigid polymer chains of poly(methyl mathacrylate)(PMMA)immobilize the emitter molecules through multiple interactions between them,giving rise to efficient RTP.Meanwhile,the loosely-packed amorphous polymer chains allow oxygen to diffuse inside,endowing the doped polymers with oxygen sensitivity.Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum,which was among the best performance of PMMA.Intriguingly,their RTP was rapidly quenched in the presence of oxygen.Furthermore,RTP microparticles with a diameter of 1.63μm were synthesized using in situ dispersion polymerization technique.Finally,oxygen sensors for quick,visual,and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis.With distinctive advantages such as an ultralong lifetime,oxygen sensitivity,ease of fabrication,and cost-effectiveness,PCSP opens a new avenue to sensitive materials for oxygen detection.展开更多
Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion...Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion resistance by the conventional surface treatments is always achieved at the expense of sacrificing the fatigue lifetime.In this study,high purity aluminum(Al)and AlMgSi alloy coatings were deposited on Mg alloys via an in-situ micro-forging(MF)assisted cold spray(MFCS)process for simultaneous higher corrosion resistance and longer fatigue lifetime.Besides contributing to a highly dense microstructure,the in-situ MF also greatly refines the grain of the deposited Al alloy coating to the sub-micrometer range due to the enhanced dynamic recrystallization and also generates notable compressive residual stress up to 210 MPa within the AlMgSi coating.The absence of secondary phases in the AlMgSi alloy coatings enable the coated Mg alloy with corrosion resistance,which is even better than its bulk AlMgSi counterparts.The unique combination of refined microstructure and the prominent compressive residual stress within the AlMgSi coatings,effectively delayed the crack initiation upon repeated dynamic loading,thereby leading to∼10 times increase in the fatigue lifetime of the Mg Alloy.However,although residual stress is also generated in the submmicro-sized grained pure Al coating,the low intrinsic strength of the coating layer leads to a lower fatigue lifetime than the uncoated Mg alloy substrate.The present work is aimed to provide a facile approach to break the trade-off between corrosion resistance improvement and fatigue lifetime of the coated Mg alloys.展开更多
The rising demand for energy storage solutions,especially in the electric vehicle and renewable energy sectors,highlights the importance of accurately predicting battery health to enhance their longevity and reliabili...The rising demand for energy storage solutions,especially in the electric vehicle and renewable energy sectors,highlights the importance of accurately predicting battery health to enhance their longevity and reliability.This article comprehensively examines various methods used to forecast battery health,including physics-based models,empirical models,and equivalent circuit models,among others.It delves into the promise of data-driven prognostics,utilizing both conventional machine learning and cuttingedge deep neural network techniques.The advantages and limitations of hybrid models are thoroughly analyzed,with a focus on the benefits of integrating diverse data sources to improve prognostic precision.Through practical case studies,the article showcases the effectiveness and flexibility of these approaches.It also critically addresses the challenges encountered in applying battery health prognostics in realworld scenarios,such as issues of scalability,complexity,and data anomalies.Despite these challenges,the article underscores the emerging opportunities brought about by recent technological,academic,and research advancements.These include the development of digital twin models for batteries,the use of data-centric AI and standardized benchmarking,the potential integration of blockchain technology for enhanced data security and transparency,and the synergy between edge and cloud computing to boost data analysis and processing.The primary goal of this article is to enrich the understanding of current battery health prognostic techniques and to inspire further research aimed at overcoming existing hurdles and tapping into new opportunities.It concludes with a visionary perspective on future research directions and potential developments in this evolving field,encouraging both researchers and practitioners to explore innovative solutions.展开更多
Employing two fully relativistic methods,the multi-reference configuration Dirac-Hartree-Fock(MCDHF)methodand the relativistic many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the ...Employing two fully relativistic methods,the multi-reference configuration Dirac-Hartree-Fock(MCDHF)methodand the relativistic many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest35 energy levels of the(1s^(2))nl configurations(where the principal quantum number n=2-6 and the angular quantum numberl=0,...,n-1)of lithium-like germanium(Ge XXX),as well as complete data on the transition wavelengths,radiativerates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magneticdipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.The results from the two methodsare consistent with each other and align well with previous accurate experimental and theoretical findings.We assess theoverall accuracies of present RMBPT results to be likely the most precise ones to date.The present fully relativistic resultsshould be helpful for soft x-ray laser research,spectral line identification,plasma modeling and diagnosing.The datasetspresented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00135.展开更多
Ground lifetime test is the most crucial experiment to assess the performance,reliability.and flight qualification of electric propulsion,and it can bring new insights for understanding the operation characteristics.T...Ground lifetime test is the most crucial experiment to assess the performance,reliability.and flight qualification of electric propulsion,and it can bring new insights for understanding the operation characteristics.This work demonstrates a full lifetime test of 140000 cycles on a Micro-Cathode-Arc Thruster(μCAT)with 160μs charging time and 86 mJ charging energy.A four-probe resistivity measurement method is utilized to investigate variations in the conductive film thickness and resistivity throughout the thruster lifespan.Direct film parameters show that the lifetime of theμCAT can be divided into three stages.In the initial stage,the film thickness decreases by 1.2μm and the resistivity increases significantly due to the high discharge intensity and intense film ablation;In the steady stage,the change of the film thickness is within 5%,and the resistivity of the film increases slowly from 0.050Ω·mm to 0.223Ω·mm.In the end stage,the resistivity exponentially increases from 0.223Ω·mm to 1.176Ω·mm,with the increase accounting for 81%,ultimately resulting in the failure of the thruster open circuit.Additionally,the evolution of discharge parameters,and the variation of plume parameters are measured throughout the life-time.The discharge characteristics also show significant differences in the duration of voltage and current in these three stages.The results of plume shape and plasma parameters are also well con-sistent with the discharge parameters and film state.These results suggest that,for evaluating the steady stage lifetime of thrusters,the film thickness is the best indicator compared to the variations in resistivity and voltage-current characteristics.For the end stage,the plasma plume morphology.discharge duration,and plume parameters can conveniently and clearly characterize the thruster failures and irregularity.展开更多
Using the modified Blonder-Tinkham-Klapwijk(BTK)theory,the interplay between the lifetime of quasi particles and the magnetic gap in a topological insulator-based ferromagnet/fwave superconductor(TI-based FM/f-wave SC...Using the modified Blonder-Tinkham-Klapwijk(BTK)theory,the interplay between the lifetime of quasi particles and the magnetic gap in a topological insulator-based ferromagnet/fwave superconductor(TI-based FM/f-wave SC)tunnel structure is theoretically studied.Two symmetries of f_(1) and f_(2) waves are considered for superconducting pairing states.The results indicate that reducing the finite quasi-particle lifetime will induce a transformation of energy-gap peaks into a zero-bias peak in tunneling conductance spectrum,as well as a transformation of energy-gap dips into a zero-bias dip in shot noise spectrum,ultimately resulting in the smoothing of the zero-bias conductance peak and the zero-bias shot noise dip.An increase in magnetic gap will suppress the tunnel conductance and shot noise when the conventional Andreev retroreflection dominates,but will enhance them when the specular Andreev reflection is dominant.Both specular Andreev reflection and conventional Andreev retro-reflection will be enhanced as the quasi-particle lifetime increases.When Fermi energy equals the magnetic gap,shot noise and tunneling conductance vanish across all energy ranges.These findings not only contribute to a better understanding of specular Andreev reflection in the FM/f-wave SC junction based on TIs but also provide insights for experimentally determining the f-wave pairing symmetry.展开更多
We present a high-resolution study on the B^(2)Π-X^(2)Πelectronic origin band spectrum of the C_(6)H radical with its center at~18990 cm^(-1).The C_(6)H radicals are produced in a pulsed supersonic slit-jet discharg...We present a high-resolution study on the B^(2)Π-X^(2)Πelectronic origin band spectrum of the C_(6)H radical with its center at~18990 cm^(-1).The C_(6)H radicals are produced in a pulsed supersonic slit-jet discharge source and detected in direct absorption by sensitive cavity ring-down spectroscopy.By using a home-made narrow linewidth nanosecond pulsed laser source,the experimental spectrum allows to resolve the A-type doublet fine structures in high-J rotational lines.A set of improved B21I state constants,including the Atype doubling parameters of p'=-1.16(9)×10^(-3)cm^(-1),Q=-1.22(7)×10^(-4)cm^(-1),are determined from analysis of the experimental spectrum.An analysis on the spectral line profile has resulted in a significant linwidth broadening of-0.05±0.01 cm^(-1),corresponding to a B^(2)Πtatelife time of~100+20 ps.The short lifetime of the excited B^(2)Πstate is proposed due to fast internal vibronic couplings to high-lying vibronic levels of lower electronic states.展开更多
In Wireless Sensor Networks(WSNs),Clustering process is widely utilized for increasing the lifespan with sustained energy stability during data transmission.Several clustering protocols were devised for extending netw...In Wireless Sensor Networks(WSNs),Clustering process is widely utilized for increasing the lifespan with sustained energy stability during data transmission.Several clustering protocols were devised for extending network lifetime,but most of them failed in handling the problem of fixed clustering,static rounds,and inadequate Cluster Head(CH)selection criteria which consumes more energy.In this paper,Stochastic Ranking Improved Teaching-Learning and Adaptive Grasshopper Optimization Algorithm(SRITL-AGOA)-based Clustering Scheme for energy stabilization and extending network lifespan.This SRITL-AGOA selected CH depending on the weightage of factors such as node mobility degree,neighbour's density distance to sink,single-hop or multihop communication and Residual Energy(RE)that directly influences the energy consumption of sensor nodes.In specific,Grasshopper Optimization Algorithm(GOA)is improved through tangent-based nonlinear strategy for enhancing the ability of global optimization.On the other hand,stochastic ranking and violation constraint handling strategies are embedded into Teaching-Learning-based Optimization Algorithm(TLOA)for improving its exploitation tendencies.Then,SR and VCH improved TLOA is embedded into the exploitation phase of AGOA for selecting better CH by maintaining better balance amid exploration and exploitation.Simulation results confirmed that the proposed SRITL-AGOA improved throughput by 21.86%,network stability by 18.94%,load balancing by 16.14%with minimized energy depletion by19.21%,compared to the competitive CH selection approaches.展开更多
Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. Th...Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.展开更多
In the digital era,retailers are keen to find out whether omni-channel retailing helps improve long-term firm performance.In this paper,we employ machine learning techniques on a large consumption data set in order to...In the digital era,retailers are keen to find out whether omni-channel retailing helps improve long-term firm performance.In this paper,we employ machine learning techniques on a large consumption data set in order to measure customer lifetime value(CLV)as the basis for determining long-term firm performance,and we provide an empirical analysis of the relationship between omni-channel retailing and CLV.The results suggest that omni-channel retailing may effectively enhance CLV.Further analysis reveals that this process is influenced by heterogeneous consumer requirements and that significant differences exist in the extent to which the omni-channel transition may influence CLV depending on consumer preferences for diversity of commodities,sensitivity to the cost of contract performance,and sensitivity to warehousing costs.Hence,retailers should provide consumers with a complete portfolio of goods and services based on target consumers’heterogeneous requirements in order to increase omni-channel efficiency.展开更多
基金the support provided by the California Department of Transportation(Caltrans)through the Fiscal Year 2023-24 grant(65A0686)for the research project titled‘Revolutions in Battery technologies and Future Electric Vehicles’。
文摘Battery technology plays a crucial role across various sectors,powering devices from smartphones to electric vehicles and supporting grid-scale energy storage.To ensure their safety and efficiency,batteries must be evaluated under diverse operating conditions.Traditional modeling techniques,which often rely on first principles and atomic-level calculations,struggle with practical applications due to incomplete or noisy data.Furthermore,the complexity of battery dynamics,shaped by physical,chemical,and electrochemical interactions,presents substantial challenges for precise and efficient modeling.The Transformer model,originally designed for natural language processing,has proven effective in time-series analysis and forecasting.It adeptly handles the extensive,complex datasets produced during battery cycles,efficiently filtering out noise and identifying critical features without extensive preprocessing.This capability positions Transformers as potent tools for tackling the intricacies of battery data.This review explores the application of customized Transformers in battery state estimation,emphasizing crucial aspects such as charging,health assessment,lifetime prediction,and safety monitoring.It highlights the distinct advantages of Transformer-based models and addresses ongoing challenges and future opportunities in the field.By combining data-driven AI techniques with empirical insights from battery analysis,these pre-trained models can deliver precise diagnostics and comprehensive monitoring,enhancing performance metrics like health monitoring,anomaly detection,and early-warning systems.This integrated approach promises significant improvements in battery technology management and application.
基金the National Institute of Health for supporting this research under grants NIH R35GM152076,NIH 1SC1GM127175-01,NIH T32GM148394.
文摘Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.
基金supported by Henan Province Science and Technology Tackling Key Issues Project(grant number:232102310166).
文摘Objective:To understand the current status and changing trends in the lifetime risk of residents in Henan Province,China to develop and die from cancer.Methods:Lifetime risk was estimated using the Adjusted for Multiple Primaries(AMP)method,incorporating cancer incidence,mortality,and all-cause mortality data from 55 cancer registries in Henan Province,China.Estimates were calculated overall and stratified by gender and area.The annual percent change(APC)in lifetime risk from 2010 to 2020,stratified by gender and cancer site,was estimated using a log-linear model.Results:In 2020,the lifetime risk of developing and dying from cancer was 30.19%(95%CI:29.63%-30.76%)and 23.62%(95%CI:23.28%-23.95%),respectively.These estimates were higher in men,with values of 31.22%(95%CI:30.59%-31.85%)for developing cancer and 26.73%(95%CI:26.29%-27.16%)for dying from cancer,compared with women,who had values of 29.02%(95%CI:28.12%-29.91%)and 20.08%(95%CI:19.51%-20.64%),respectively.There were also geographical differences,with higher estimates in urban areas compared with rural areas.Residents had the highest lifetime risk of developing lung cancer,with a rate of 6.94%,followed by breast cancer(4.14%),stomach cancer(3.95%),esophageal cancer(3.75%),and liver cancer(2.86%).Similarly,the highest lifetime risk of dying from cancer was observed for the following sites:lung(5.99%),stomach(3.60%),esophagus(3.39%),liver(2.78%),and colorectum(1.55%).Overall,the lifetime risk of developing cancer increased,with an APC of 0.75%(P<0.05).Varying trends were observed across different cancer sites.There were gradual decreases in nasopharynx,esophagus,stomach,and liver cancers.Conversely,increasing trends were noted for most other sites,with the highest APCs observed in thyroid,prostate,lymphoma,kidney,and gallbladder cancers.Conclusion:The lifetime risks of developing and dying from cancer were 30.19%and 23.62%,respectively.Variations in cancer risk across different regions,genders,specific cancer sites,and over calendar years provide important information for cancer prevention and policy making in the population.
基金financially supported by the National Natural Science Foundation of China(Nos.52306183,12272245,11832007,12172238)the Natural Science Foundation of Zhejiang Province,China(No.LQ23E050022)+1 种基金the Natural Science Foundation of Sichuan Province,China(Nos.2022NSFSC0324,2022JDJQ0011)the Open Project of Failure Mechanics and Engineering Disaster Prevention,Key Laboratory of Sichuan Province,China(No.FMEDP202305)。
文摘In order to accurately evaluate the creep-fatigue lifetime of GH720Li superalloy,a lifetime prediction model was established,reflecting the interaction between creep damage and low-cycle fatigue damage.The creep-fatigue lifetime prediction results of GH720Li superalloy with an average grain size of 17.3μm were essentially within a scatter band of 2 times,indicating a strong agreement between the predicted lifetimes and experimental data.Then,considering that the grain size of the dual-property turbine disc decreases from the rim to the center,a grain-size-sensitive lifetime prediction model for creep-fatigue was established by introducing the ratio of grain boundary area.The improved model overcame the limitation of most traditional prediction methods,which failed to reflect the relationship between grain size and creep-fatigue lifetime.
基金supported by the National Key R&D Program of China (No. 2023YFA1606401 and 2018YFA0404401)the Young Scholar of Regional Development,CAS ([2023] 15)+1 种基金Chinese Academy of Sciences Stable Support for Young Teams in Basic Research (No. YSBR-002)Special Fund for Strategic Pilot Technology of Chinese Academy of Sciences (No. XDB34000000)
文摘Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions.Owing to the nondestructive ion detection features of Schottky noise detectors,the number of stored ions in the ring is determined by the peak area in the measured revolution frequency spectrum.Because of their intrinsic amplitude-frequency characteristic(AFC),Schottky detector systems exhibit varying sensitivities at different frequencies.Using low-energy electron-cooled stored ions,a new method is developed to calibrate the AFC curve of the Schottky detector system of the Experimental Cooler Storage Ring(CSRe)storage ring located in Lanzhou,China.Using the amplitude-calibrated frequency spectrum,a notable refinement was observed in the precision of both the peak position and peak area.As a result,the storage lifetimes of the electron-cooled fully ionized^(56)Fe^(26+)ions were determined with high precision at beam energies of 13.7 and 116.4 MeV/u,despite of frequency drifts during the experiment.When electron cooling was turned off,the effective vacuum condition experienced by the 116.4 MeV/u^(56)Fe^(26+)ions was determined using amplitude-calibrated spectra,revealing a value of 2×10^(−10)mbar,which is consistent with vacuum gauge readings along the CSRe ring.The method reported herein will be adapted for the next-generation storage ring of the HIAF facility under construction in Huizhou,China.It can also be adapted to other storage ring facilities worldwide to improve precision and enhance lifetime measurements using many ions in the ring.
基金supported by the Natural Science Foundation of Jiangsu Province(Grant.BK20232042).
文摘Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LEDs[7,8].However,it took much longer time for GaN-based LDs to achieve high power,high wall plug efficiency,and long lifetime.Until 2019,Nichia reported blue LDs with these performances[9],which open wide applications with GaN-based blue LDs.
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2023YFB3609500 and 2023YFB3609502)the National Natural Science Foundation of China (Grant No. 62274137)+1 种基金the Natural Science Foundation of Jiangxi Province, China (Grant No. 20232BAB202043)the Science and Technology Project of Fujian Province of China (Grant No. 2020I0001)。
文摘A minority carrier lifetime of 25.46 μs in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H-SiC epilayer by reducing carbon vacancies. However, this process also generates carbon clusters with limited diffusivity and contributes to the enlargement of surface pits on the 4H-SiC. High-temperature hydrogen annealing effectively reduces stacking fault and dislocation density. Moreover, electron spin resonance analysis indicates a significant reduction in carbon vacancy defects after hydrogen annealing. The mechanisms of the elimination of carbon vacancies by hydrogen annealing include the decomposition of carbon clusters formed during thermal oxidation and the low-pressure selective etching by hydrogen,which increases the carbon content on the 4H-SiC surface and facilitates carbon diffusion. Consequently, the combination of thermal oxidation and hydrogen annealing eliminates carbon vacancies more effectively, substantially enhancing the minority carrier lifetime in P-type 4H-SiC. This improvement is advantageous for the application of high-voltage SiC bipolar devices.
基金funded by The Vietnam Ministry of Education and Training under project number B2024-BKA-12.
文摘Minority carrier lifetimesτare a fundamental parameter in semiconductor devices,representing the average time it takes for excess minority carriers to recombine.This characteristic is crucial for understanding and optimizing the performance of semiconductor materials,as it directly influences charge carrier dynamics and overall device efficiency.This work presents a development of PbS thin film deposited by thermal evaporation,at which the PbS thin film was further employed for structural,optical properties,andτ.Especially,the PbS film is probed with an in-house setup for identifying theτ.The procedure is to subject the PbS thin film with a flashlight from a light source with a middle rotating frequency.The derivedτin the in-house characterization setup agrees well with the value from the higher cost characterizing approach of photoluminescence.Therefore,the in-house setup provides additional tools for identifying theτvalues for semiconductor devices.
文摘The widespread usage of rechargeable batteries in portable devices,electric vehicles,and energy storage systems has underscored the importance for accurately predicting their lifetimes.However,data scarcity often limits the accuracy of prediction models,which is escalated by the incompletion of data induced by the issues such as sensor failures.To address these challenges,we propose a novel approach to accommodate data insufficiency through achieving external information from incomplete data samples,which are usually discarded in existing studies.In order to fully unleash the prediction power of incomplete data,we have investigated the Multiple Imputation by Chained Equations(MICE)method that diversifies the training data through exploring the potential data patterns.The experimental results demonstrate that the proposed method significantly outperforms the baselines in the most considered scenarios while reducing the prediction root mean square error(RMSE)by up to 18.9%.Furthermore,we have also observed that the penetration of incomplete data benefits the explainability of the prediction model through facilitating the feature selection.
基金supported by the National Key R&D Program of China(2020YFA0712901).
文摘We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the unit speed. The models, without or with immigration, are constructed as measure-valued processes by pathwise unique solutions of stochastic equations driven by time-space Poisson random measures. In the subcritical branching case, we give a sufficient condition for the ergodicity of the process with immigration. Two large number laws and a central limit theorem of the occupation times are proved.
基金National Natural Science Foundation of China(No.22475241)Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515010826 and 2023A1515012696)the Fundamental Research Funds for the Central Universities(Nos.17lgjc03 and 18lgpy04).
文摘Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polymers exhibit a short RTP lifetime(<1 s)because of their unstable triplet excitons.Herein,a new strategy of polymer chain stabilized phosphorescence(PCSP),which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response,has been reported.The rigid polymer chains of poly(methyl mathacrylate)(PMMA)immobilize the emitter molecules through multiple interactions between them,giving rise to efficient RTP.Meanwhile,the loosely-packed amorphous polymer chains allow oxygen to diffuse inside,endowing the doped polymers with oxygen sensitivity.Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum,which was among the best performance of PMMA.Intriguingly,their RTP was rapidly quenched in the presence of oxygen.Furthermore,RTP microparticles with a diameter of 1.63μm were synthesized using in situ dispersion polymerization technique.Finally,oxygen sensors for quick,visual,and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis.With distinctive advantages such as an ultralong lifetime,oxygen sensitivity,ease of fabrication,and cost-effectiveness,PCSP opens a new avenue to sensitive materials for oxygen detection.
基金supported by the National Natural Science Foundation of China(51875443)Guangdong Basic and Applied Basic Research Foundation(2019B1515120016,202002030290).
文摘Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion resistance by the conventional surface treatments is always achieved at the expense of sacrificing the fatigue lifetime.In this study,high purity aluminum(Al)and AlMgSi alloy coatings were deposited on Mg alloys via an in-situ micro-forging(MF)assisted cold spray(MFCS)process for simultaneous higher corrosion resistance and longer fatigue lifetime.Besides contributing to a highly dense microstructure,the in-situ MF also greatly refines the grain of the deposited Al alloy coating to the sub-micrometer range due to the enhanced dynamic recrystallization and also generates notable compressive residual stress up to 210 MPa within the AlMgSi coating.The absence of secondary phases in the AlMgSi alloy coatings enable the coated Mg alloy with corrosion resistance,which is even better than its bulk AlMgSi counterparts.The unique combination of refined microstructure and the prominent compressive residual stress within the AlMgSi coatings,effectively delayed the crack initiation upon repeated dynamic loading,thereby leading to∼10 times increase in the fatigue lifetime of the Mg Alloy.However,although residual stress is also generated in the submmicro-sized grained pure Al coating,the low intrinsic strength of the coating layer leads to a lower fatigue lifetime than the uncoated Mg alloy substrate.The present work is aimed to provide a facile approach to break the trade-off between corrosion resistance improvement and fatigue lifetime of the coated Mg alloys.
基金funded by the Independent Innovation Projects of the Hubei Longzhong Laboratory(2022ZZ-24)the Central Government to Guide Local Science and Technology Development fund Projects of Hubei Province(2022BGE267).
文摘The rising demand for energy storage solutions,especially in the electric vehicle and renewable energy sectors,highlights the importance of accurately predicting battery health to enhance their longevity and reliability.This article comprehensively examines various methods used to forecast battery health,including physics-based models,empirical models,and equivalent circuit models,among others.It delves into the promise of data-driven prognostics,utilizing both conventional machine learning and cuttingedge deep neural network techniques.The advantages and limitations of hybrid models are thoroughly analyzed,with a focus on the benefits of integrating diverse data sources to improve prognostic precision.Through practical case studies,the article showcases the effectiveness and flexibility of these approaches.It also critically addresses the challenges encountered in applying battery health prognostics in realworld scenarios,such as issues of scalability,complexity,and data anomalies.Despite these challenges,the article underscores the emerging opportunities brought about by recent technological,academic,and research advancements.These include the development of digital twin models for batteries,the use of data-centric AI and standardized benchmarking,the potential integration of blockchain technology for enhanced data security and transparency,and the synergy between edge and cloud computing to boost data analysis and processing.The primary goal of this article is to enrich the understanding of current battery health prognostic techniques and to inspire further research aimed at overcoming existing hurdles and tapping into new opportunities.It concludes with a visionary perspective on future research directions and potential developments in this evolving field,encouraging both researchers and practitioners to explore innovative solutions.
基金supported by the Research Foundation for Higher Level Talents of West Anhui University(Grant No.WGKQ2021005).
文摘Employing two fully relativistic methods,the multi-reference configuration Dirac-Hartree-Fock(MCDHF)methodand the relativistic many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest35 energy levels of the(1s^(2))nl configurations(where the principal quantum number n=2-6 and the angular quantum numberl=0,...,n-1)of lithium-like germanium(Ge XXX),as well as complete data on the transition wavelengths,radiativerates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magneticdipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.The results from the two methodsare consistent with each other and align well with previous accurate experimental and theoretical findings.We assess theoverall accuracies of present RMBPT results to be likely the most precise ones to date.The present fully relativistic resultsshould be helpful for soft x-ray laser research,spectral line identification,plasma modeling and diagnosing.The datasetspresented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00135.
基金supported by the National Natural Science Foundation of China(No.52177128).
文摘Ground lifetime test is the most crucial experiment to assess the performance,reliability.and flight qualification of electric propulsion,and it can bring new insights for understanding the operation characteristics.This work demonstrates a full lifetime test of 140000 cycles on a Micro-Cathode-Arc Thruster(μCAT)with 160μs charging time and 86 mJ charging energy.A four-probe resistivity measurement method is utilized to investigate variations in the conductive film thickness and resistivity throughout the thruster lifespan.Direct film parameters show that the lifetime of theμCAT can be divided into three stages.In the initial stage,the film thickness decreases by 1.2μm and the resistivity increases significantly due to the high discharge intensity and intense film ablation;In the steady stage,the change of the film thickness is within 5%,and the resistivity of the film increases slowly from 0.050Ω·mm to 0.223Ω·mm.In the end stage,the resistivity exponentially increases from 0.223Ω·mm to 1.176Ω·mm,with the increase accounting for 81%,ultimately resulting in the failure of the thruster open circuit.Additionally,the evolution of discharge parameters,and the variation of plume parameters are measured throughout the life-time.The discharge characteristics also show significant differences in the duration of voltage and current in these three stages.The results of plume shape and plasma parameters are also well con-sistent with the discharge parameters and film state.These results suggest that,for evaluating the steady stage lifetime of thrusters,the film thickness is the best indicator compared to the variations in resistivity and voltage-current characteristics.For the end stage,the plasma plume morphology.discharge duration,and plume parameters can conveniently and clearly characterize the thruster failures and irregularity.
文摘Using the modified Blonder-Tinkham-Klapwijk(BTK)theory,the interplay between the lifetime of quasi particles and the magnetic gap in a topological insulator-based ferromagnet/fwave superconductor(TI-based FM/f-wave SC)tunnel structure is theoretically studied.Two symmetries of f_(1) and f_(2) waves are considered for superconducting pairing states.The results indicate that reducing the finite quasi-particle lifetime will induce a transformation of energy-gap peaks into a zero-bias peak in tunneling conductance spectrum,as well as a transformation of energy-gap dips into a zero-bias dip in shot noise spectrum,ultimately resulting in the smoothing of the zero-bias conductance peak and the zero-bias shot noise dip.An increase in magnetic gap will suppress the tunnel conductance and shot noise when the conventional Andreev retroreflection dominates,but will enhance them when the specular Andreev reflection is dominant.Both specular Andreev reflection and conventional Andreev retro-reflection will be enhanced as the quasi-particle lifetime increases.When Fermi energy equals the magnetic gap,shot noise and tunneling conductance vanish across all energy ranges.These findings not only contribute to a better understanding of specular Andreev reflection in the FM/f-wave SC junction based on TIs but also provide insights for experimentally determining the f-wave pairing symmetry.
基金supported by the National Natural Foundation of China(No.21827804,No.22103075,No.22173089)the National Key R&D Program of China(No.2021YFA0716801,No.2017YFA0303502)。
文摘We present a high-resolution study on the B^(2)Π-X^(2)Πelectronic origin band spectrum of the C_(6)H radical with its center at~18990 cm^(-1).The C_(6)H radicals are produced in a pulsed supersonic slit-jet discharge source and detected in direct absorption by sensitive cavity ring-down spectroscopy.By using a home-made narrow linewidth nanosecond pulsed laser source,the experimental spectrum allows to resolve the A-type doublet fine structures in high-J rotational lines.A set of improved B21I state constants,including the Atype doubling parameters of p'=-1.16(9)×10^(-3)cm^(-1),Q=-1.22(7)×10^(-4)cm^(-1),are determined from analysis of the experimental spectrum.An analysis on the spectral line profile has resulted in a significant linwidth broadening of-0.05±0.01 cm^(-1),corresponding to a B^(2)Πtatelife time of~100+20 ps.The short lifetime of the excited B^(2)Πstate is proposed due to fast internal vibronic couplings to high-lying vibronic levels of lower electronic states.
文摘In Wireless Sensor Networks(WSNs),Clustering process is widely utilized for increasing the lifespan with sustained energy stability during data transmission.Several clustering protocols were devised for extending network lifetime,but most of them failed in handling the problem of fixed clustering,static rounds,and inadequate Cluster Head(CH)selection criteria which consumes more energy.In this paper,Stochastic Ranking Improved Teaching-Learning and Adaptive Grasshopper Optimization Algorithm(SRITL-AGOA)-based Clustering Scheme for energy stabilization and extending network lifespan.This SRITL-AGOA selected CH depending on the weightage of factors such as node mobility degree,neighbour's density distance to sink,single-hop or multihop communication and Residual Energy(RE)that directly influences the energy consumption of sensor nodes.In specific,Grasshopper Optimization Algorithm(GOA)is improved through tangent-based nonlinear strategy for enhancing the ability of global optimization.On the other hand,stochastic ranking and violation constraint handling strategies are embedded into Teaching-Learning-based Optimization Algorithm(TLOA)for improving its exploitation tendencies.Then,SR and VCH improved TLOA is embedded into the exploitation phase of AGOA for selecting better CH by maintaining better balance amid exploration and exploitation.Simulation results confirmed that the proposed SRITL-AGOA improved throughput by 21.86%,network stability by 18.94%,load balancing by 16.14%with minimized energy depletion by19.21%,compared to the competitive CH selection approaches.
基金financially supported by Natural Science Foundation of Sichuan Province (No. 2022NSFSC0296)the National Natural Science Foundation of China (Nos. 51903118and U19A2096)State Key Laboratory of Polymer Materials Engineering (No. sklpme2020-1-07, Sichuan University)。
文摘Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.
基金the National Social Science Foundation of China(NSSFC)“Study on the Digital Transition of China’s Retail Business”(Grant No.18BJY176).
文摘In the digital era,retailers are keen to find out whether omni-channel retailing helps improve long-term firm performance.In this paper,we employ machine learning techniques on a large consumption data set in order to measure customer lifetime value(CLV)as the basis for determining long-term firm performance,and we provide an empirical analysis of the relationship between omni-channel retailing and CLV.The results suggest that omni-channel retailing may effectively enhance CLV.Further analysis reveals that this process is influenced by heterogeneous consumer requirements and that significant differences exist in the extent to which the omni-channel transition may influence CLV depending on consumer preferences for diversity of commodities,sensitivity to the cost of contract performance,and sensitivity to warehousing costs.Hence,retailers should provide consumers with a complete portfolio of goods and services based on target consumers’heterogeneous requirements in order to increase omni-channel efficiency.
