A gradient system and a skew-gradient system can be merged into a combined gradient system. The differential equations of the combined gradient system are established and its property is studied. If a mechanical syste...A gradient system and a skew-gradient system can be merged into a combined gradient system. The differential equations of the combined gradient system are established and its property is studied. If a mechanical system can be represented as a combined gradient system, the stability of the mechanical system can be studied by using the property of the combined gradient system. Some examples are given to illustrate the applications of the results.展开更多
All types of gradient systems and their properties are discussed. Two problems connected with gradient systems and mechanical systems are studied. One is the direct problem of transforming a mechanical system into a g...All types of gradient systems and their properties are discussed. Two problems connected with gradient systems and mechanical systems are studied. One is the direct problem of transforming a mechanical system into a gradient system, and the other is the inverse problem, which is transforming a gradient system into a mechanical system.展开更多
This paper considers a new approach to solving the problem of quantitative estimation of the microseism energy for underground sources that is based on the synthesis of noise interferometry and the passive seismic met...This paper considers a new approach to solving the problem of quantitative estimation of the microseism energy for underground sources that is based on the synthesis of noise interferometry and the passive seismic method of the gradient system. The selection of a seismic field of the underground sources is considered in an experiment conducted in the Tien Shan region. The peculiarities of approach include the separation of vertical microseisms in the ambient seismic noise field structure according to the data of the seismic gradient system and a passive noise interferometry diagram, where microseisms from the underground sources are used as the seismic signal source. It is shown that the use of noise interferometry and passive seismic gradient system allows using the synchronous microseism recordings in a small number of points for passive medium sensing, and leads to the restoration of unknown energy parameters of the seismic field of underground sources.展开更多
This paper deals with an abstract periodic gradient system in which the gradient is taken with respect to a variable metric. We obtain an existence and uniqueness result via the application of a global inverse theorem.
In this paper, we establish the existence of solutions for gradient systems ofevolution under some type （M） and semi-coerciveness conditions. The main result is appliedin order to solve nonlinear diffusion equations...In this paper, we establish the existence of solutions for gradient systems ofevolution under some type （M） and semi-coerciveness conditions. The main result is appliedin order to solve nonlinear diffusion equations involving nonconvex energies.展开更多
In this paper,the Riemann problem of a Chapman-Jouguet combustion model for the pressure-gradient equations is considered.By analyzing in phase space,existence and uniqueness of the solution to the Riemann problem are...In this paper,the Riemann problem of a Chapman-Jouguet combustion model for the pressure-gradient equations is considered.By analyzing in phase space,existence and uniqueness of the solution to the Riemann problem are obtained constructively under the global entropy conditions.展开更多
Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is reveal...Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is revealed that trapezoidal fins tend to be more efficient,particularly when material optimization is critical.Motivated by the increasing need for sustainable energy management,this work analyses the thermal performance of inclined trapezoidal and rectangular porous fins utilising a unique hybrid nanofluid.The effectiveness of nanoparticles in a working fluid is primarily determined by their thermophysical properties;hence,optimising these properties can significantly improve overall performance.This study considers the dispersion of Graphene Oxide(GO)and Molybdenum Disulfide in the base fluid,engine oil.Temperature profiles are analysed by altering the radiative,porosity,wet porous,and angle of inclination parameters.Surface and contour plots are constructed by using the Lobatto IIIa Collocation Method with BVP5C solver in MATLAB and Gradient Descent Optimisation to predict the combined heat transfer rate.According to the study,fluid temperature consistently decreases when the angle of inclination,wet porous parameter,porosity parameter,and radiative parameter increase,suggesting significantly improved heat dissipation.The trapezoidal fin consistently exhibits a superior heat transfer mechanism than a rectangular fin.It is found that the trapezoidal fin transmits heat at a rate that is 0.05%higher than that of the rectangular fin.Validation of the present study is done through the comparison of previous studies.This research provides useful design insights for sophisticated engineering uses,including electrical cooling devices,heat exchangers,radiators,and solar heaters.展开更多
The stability of solutions of Herglotz-type equations for non-autonomous non-conservative systems is studied by means of generalized gradient method.Firstly,Herglotz-type equations for non-conservative systems are giv...The stability of solutions of Herglotz-type equations for non-autonomous non-conservative systems is studied by means of generalized gradient method.Firstly,Herglotz-type equations for non-conservative systems are given and expressed as contravariant algebraic form.Secondly,two classes of generalized gradient systems are introduced.Thirdly,the conditions for the transformation of Herglotz-type equations into generalized gradient systems are given,and the solutions of Herglotz-type equations and the stability of the solutions are analyzed.Finally,for each case discussed in this paper,the calculation process is demonstrated in detail to show that the method is effective.展开更多
Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions ...Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.展开更多
An analytical method is proposed with the “stiffness gradient of the response” as a sensitivity metric, and the relationships between the vibration responses and stiffness changes are established. First, a 2-degree-...An analytical method is proposed with the “stiffness gradient of the response” as a sensitivity metric, and the relationships between the vibration responses and stiffness changes are established. First, a 2-degree-of-freedom (DOF) system is used as an example to propose a stiffness gradient-based evaluation method, taking the effective control bandwidth ratio as a metric of effectiveness. The results show that there is an optimal mass ratio in both variable mass and variable stiffness cases. Then, a typical 16-DOF system is used to investigate the frequency domain characteristics of the stiffness gradient values in the complex system. The distributions of stiffness gradient values show multiple peak intervals corresponding to the sensitive regions for vibration control. By assigning random mass parameters, a significant exponential decay relationship between the subsystem’s mass and effective control is identified, emphasizing the importance of the optimal mass ratio. The finite-element simulation results of solid plate models with springs and oscillators further validate the theoretical results. In short, the gradient value of stiffness effectively quantifies the effects of subsystems on vibration control, providing an analytical tool for active control in complex systems. The identified exponential decay relationship offers meaningful guidance for implementation strategies.展开更多
Changes in agricultural land use affect ecosystem services and their interactions.However,the differential influences of agricultural land use transitions under different topographical gradients on ecosystem service i...Changes in agricultural land use affect ecosystem services and their interactions.However,the differential influences of agricultural land use transitions under different topographical gradients on ecosystem service interactions remain poorly understood,which limits the integrated management of agricultural systems.The objectives of this study were to analyze the transitional trends of major agricultural land types across distinct topographical gradients and to probe the differential impacts of these transitions on ecosystem service interactions.Using Hangzhou of China as the study area,the analysis focused on four major agricultural land use types(arable land,orchard,tea garden,and abandoned land).The GTWR model was applied to investigate spatiotemporal non-stationarity in the impacts of their transitions on the ecosystem service trade-offs and synergies.The results showed that during 2010–2020,the agricultural land use pattern in plain areas became more diversified and fragmented,while it shifted towards greater homogeneity and contiguity in hilly and mountainous areas.Between 2010–2015 and 2015–2020,the dominant output type of agricultural land use transition was arable land.The dominant input type in plain areas shifted from arable land to orchard,whereas in hilly and mountainous areas,it was orchard and tea garden.The higher synergy between habitat quality and other ecosystem services primarily occurred in plain areas.Over time,the higher synergy between carbon sequestration and soil retention predominantly shifted from mountainous areas to plain areas.A variety of abandoned types across different topographical gradients fostered synergies by reducing the supply capacity of various ecosystem services.Trade-offs between ecosystem services in hilly and mountainous areas could be alleviated by converting arable land into orchard and tea garden.These findings highlight the importance of adopting differentiated,dynamic,and systematic measures for agricultural spatial development in implementing ecosystem management across different topographical gradients.展开更多
Cyber-physical systems(CPS)represent a sophisticated integration of computational and physical components that power critical applications such as smart manufacturing,healthcare,and autonomous infrastructure.However,t...Cyber-physical systems(CPS)represent a sophisticated integration of computational and physical components that power critical applications such as smart manufacturing,healthcare,and autonomous infrastructure.However,their extensive reliance on internet connectivity makes them increasingly susceptible to cyber threats,potentially leading to operational failures and data breaches.Furthermore,CPS faces significant threats related to unauthorized access,improper management,and tampering of the content it generates.In this paper,we propose an intrusion detection system(IDS)optimized for CPS environments using a hybrid approach by combining a natureinspired feature selection scheme,such as Grey Wolf Optimization(GWO),in connection with the emerging Light Gradient Boosting Machine(LightGBM)classifier,named as GWO-LightGBM.While gradient boosting methods have been explored in prior IDS research,our novelty lies in proposing a hybrid approach targeting CPS-specific operational constraints,such as low-latency response and accurate detection of rare and critical attack types.We evaluate GWO-LightGBM against GWO-XGBoost,GWO-CatBoost,and an artificial neural network(ANN)baseline using the NSL-KDD and CIC-IDS-2017 benchmark datasets.The proposed models are assessed across multiple metrics,including accuracy,precision,recall,and F1-score,with an emphasis on class-wise performance and training efficiency.The proposed GWO-LightGBM model achieves the highest overall accuracy(99.73%)for NSL-KDD and(99.61%)for CIC-IDS-2017,demonstrating superior performance in detecting minority classes such as Remote-to-Local(R2L)and Other attacks—commonly overlooked by other classifiers.Moreover,the proposed model consumes lower training time,highlighting its practical feasibility and scalability for real-time CPS deployment.展开更多
A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element ...A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element simulation.The analysis was verified by an impact experiment.Results show that the high-level thickness and appropriate percentage of Ti alloy at the upper side of the gradient structure provide greater impact resistance against the bullet,which increases the warhead breakage and enhances the anti-penetration performance.In addition,during the impact process,the stress is transmitted and reflected in the form of waves in each layer of the target plate,and the interaction between the compression and tension waves causes non-synergistic deformation of the target plate and leads to delamination.The gradient target plate takes penetration resistance a step further through the higher energy absorption rate and more consumption of the bullet kinetic energy.This research provides a theoretical basis for the application of gradient structures in metallic laminated armor.展开更多
Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with pha...Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.展开更多
Recycling spent lithium-ion(Li+)batteries is critical for achieving environmental conservation and the strategic recovery of essential resources.Compared with conventional methods for recovering cathode materials,whic...Recycling spent lithium-ion(Li+)batteries is critical for achieving environmental conservation and the strategic recovery of essential resources.Compared with conventional methods for recovering cathode materials,which are energy-intensive and prone to secondary pollution,the direct regeneration approach has emerged as a rapid and highly efficient method,gaining widespread attention in recent years.However,this approach faces major challenges,including degraded electrochemical performances and limited economic value.This study,therefore,proposes a high-value direct regeneration strategy to convert degraded spent LiFePO_(4)(S-LFP)into a gradient manganese(Mn)-doped regenerated LiFe_(0.7)Mn_(0.3)PO_(4)/C(R-LFMP)composite.This method leverages the inherent microcracks and Li vacancies present in S-LFP,likely acting as diffusion channels for the Mn^(2+)/Li^(+)ions.Through a two-step mechanochemical ball-milling and carbothermal reduction process,this approach achieves simultaneous Li replenishment and surface-localised Mn gradient doping with enhanced structural control.Notably,the R-LFMP exhibits an exceptional electrochemical performance.At 0.1 C,it delivers a discharge capacity of 161.4 mA h g^(−1)and an energy density of 563.5 Wh kg^(−1)(representing a 60.5%improvement over S-LFP).Additionally,it maintains 83%capacity retention after 900 cycles at 0.5C,a considerable enhancement compared to commercial LFMP(62%).Furthermore,the regenerated cathode material generates a net profit of$7.102 kg^(−1),surpassing the profitability of conventional recycling methods by 90%.Overall,this study introduces a transformative and sustainable LFP regeneration technology,achieving breakthroughs in electrochemical restoration and high-value recycling,while paving the way for the closed-loop utilisation of LFP-based energy storage systems.展开更多
Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fos...Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fosters centers of endemism,and they harbor over 85%of global species diversity(Zhao et al.,2022).Consequently,mountains are key systems for exploring biodiversity patterns along elevational gradients,where species richness often follows four recognized models:monotonic decrease,unimodal pattern(forward and backward peak patterns),and low plateau followed by a decrease along the elevational gradient(McCain et al.,2010).展开更多
Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensio...Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensional soil column experiments under a stepwise increase in hydraulic gradient(i),aiming to evaluate the critical hydraulic gradient(icrit)as a function of the size ratio between sand and clay,clay type,and ionic concentration.It was found that icrit was less than 0.1 for all sand-clay mixtures examined in this study.In addition,the lower peak concentrations of filtrated clay observed in sand-illite mixtures,compared to those of sand-kaolinite mixtures at the same level of i,suggest that illite particles are more susceptible to suffusion.Overall,the observed breakthrough curves,mass fraction of filtrated clay,volume of outflow,and total injection time presented in this study highlight the importance of considering clay type,sand-to-clay size ratio,and ionic concentration when assessing the suffusion behavior of clay-containing soils under a stepwise increase in hydraulic gradient.展开更多
Transformer models face significant computational challenges in private inference(PI).Existing optimization methods often rely on isolated techniques,neglecting joint structural and operational improvements.We propose...Transformer models face significant computational challenges in private inference(PI).Existing optimization methods often rely on isolated techniques,neglecting joint structural and operational improvements.We propose IG-3D,a unified framework that integrates structured compression and operator approximation through accurate importance assessment.Our approach first evaluates attention head importance using Integrated Gradients(IG),offering greater stability and theoretical soundness than gradient-based methods.We then apply a threedimensional optimization:(1)structurally pruning redundant attention heads;(2)replacing Softmax with adaptive polynomial approximation to avoid exponential computations;(3)implementing layer-wise GELU substitution to accommodate different layer characteristics.A joint thresholdmechanism coordinates compression across dimensions under accuracy constraints.Experimental results on the GLUE benchmark show that our method achieves an average 2.9×speedup in inference latency and a 50%reduction in communication cost,while controlling the accuracy loss within 2.3%,demonstrating significant synergistic effects and a superior accuracy-efficiency trade-off compared to single-technique optimization strategies.展开更多
Anammox bacteria in constructed wetlands(CWs)play pivotal role in sustainable nitrogen transformation,yet existing studies lack comprehensive analysis of environmental gradients and microbial interactions,both key fac...Anammox bacteria in constructed wetlands(CWs)play pivotal role in sustainable nitrogen transformation,yet existing studies lack comprehensive analysis of environmental gradients and microbial interactions,both key factors in anammox bacteria enrichment.This study investigated the mechanisms driving anammox bacteria enrichment in lab-scale simulated CWs treating high-nitrogen wastewater,focusing on bacterial community re-sponses across wetland layers with various strategies,including continuous up-flow influent,nitrogen loading increase,effluent recirculation,intermittent influent,and anammox bacteria inoculation.Results showed that total relative and absolute abundances of anammox bacteria ranged from 0.77%to 12.50%and from 0.13 to 6.46×10^(7) copies/g,respectively.Dissolved oxygen and pH had significant positive correlations with the absolute abundance of anammox bacteria,while organic matter and nitrate negatively impacted their relative abundance.Permutational multivariate analysis of variance indicated that spatial heterogeneity explained more variation in anammox bacteria abundance(43.44%)compared to operational strategies(8.58%).In terms of microbial interactions,60 dominant species exhibited potential correlations with anammox bacteria,comprising 170 interactions(105 positive and 65 negative),which suggested that anammox bacteria generally foster cooperative relationships with dominant bacteria.Notably,significant interspecies interactions were observed between Candidatus Kuenenia(dominant anammox bacteria in CWs)and species within the genera Chitinivibrio-nia and Anaerolineaceae,suggesting that microbial interactions primarily manifest as indirect facilitative effects rather than direct mutualistic relationships.Given that the Normalized Stochasticity Ratio in CWs were<50%,this study inferred that environmental gradients have greater influence on anammox bacteria than microbial interactions.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
基金supported by the National Natural Science Foundation of China(Grant Nos.11372169 and 11272050)
文摘A gradient system and a skew-gradient system can be merged into a combined gradient system. The differential equations of the combined gradient system are established and its property is studied. If a mechanical system can be represented as a combined gradient system, the stability of the mechanical system can be studied by using the property of the combined gradient system. Some examples are given to illustrate the applications of the results.
基金supported by the National Natural Science Foundation of China (Grant 11272050)
文摘All types of gradient systems and their properties are discussed. Two problems connected with gradient systems and mechanical systems are studied. One is the direct problem of transforming a mechanical system into a gradient system, and the other is the inverse problem, which is transforming a gradient system into a mechanical system.
基金The data processing programs,development and implementation of the gradient array system are partially performed with the grant support from the Russian Foundation for Basic Research(No.20-05-00475)The subjects relating to the correlation of geophysical parameters with the average stress-strain behaviour of the geological environment are explored within the Russian State Governmental Task of the Research Station of the Russian Academy of Sciences(No.AAAA-A19-119020190063-2)。
文摘This paper considers a new approach to solving the problem of quantitative estimation of the microseism energy for underground sources that is based on the synthesis of noise interferometry and the passive seismic method of the gradient system. The selection of a seismic field of the underground sources is considered in an experiment conducted in the Tien Shan region. The peculiarities of approach include the separation of vertical microseisms in the ambient seismic noise field structure according to the data of the seismic gradient system and a passive noise interferometry diagram, where microseisms from the underground sources are used as the seismic signal source. It is shown that the use of noise interferometry and passive seismic gradient system allows using the synchronous microseism recordings in a small number of points for passive medium sensing, and leads to the restoration of unknown energy parameters of the seismic field of underground sources.
文摘This paper deals with an abstract periodic gradient system in which the gradient is taken with respect to a variable metric. We obtain an existence and uniqueness result via the application of a global inverse theorem.
文摘In this paper, we establish the existence of solutions for gradient systems ofevolution under some type （M） and semi-coerciveness conditions. The main result is appliedin order to solve nonlinear diffusion equations involving nonconvex energies.
基金Project supported by the National Natural Science Foundation of China (Grant No.10971130)and the Shanghai Leading Academic Discipline Project (Grant No.J50101)
文摘In this paper,the Riemann problem of a Chapman-Jouguet combustion model for the pressure-gradient equations is considered.By analyzing in phase space,existence and uniqueness of the solution to the Riemann problem are obtained constructively under the global entropy conditions.
基金supported by the“Regional Innovation System&Education(RISE)”through the Seoul RISE Center,funded by the Ministry of Education(MOE)and the Seoul Metropolitan Government(2025-RISE-01-027-04).
文摘Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is revealed that trapezoidal fins tend to be more efficient,particularly when material optimization is critical.Motivated by the increasing need for sustainable energy management,this work analyses the thermal performance of inclined trapezoidal and rectangular porous fins utilising a unique hybrid nanofluid.The effectiveness of nanoparticles in a working fluid is primarily determined by their thermophysical properties;hence,optimising these properties can significantly improve overall performance.This study considers the dispersion of Graphene Oxide(GO)and Molybdenum Disulfide in the base fluid,engine oil.Temperature profiles are analysed by altering the radiative,porosity,wet porous,and angle of inclination parameters.Surface and contour plots are constructed by using the Lobatto IIIa Collocation Method with BVP5C solver in MATLAB and Gradient Descent Optimisation to predict the combined heat transfer rate.According to the study,fluid temperature consistently decreases when the angle of inclination,wet porous parameter,porosity parameter,and radiative parameter increase,suggesting significantly improved heat dissipation.The trapezoidal fin consistently exhibits a superior heat transfer mechanism than a rectangular fin.It is found that the trapezoidal fin transmits heat at a rate that is 0.05%higher than that of the rectangular fin.Validation of the present study is done through the comparison of previous studies.This research provides useful design insights for sophisticated engineering uses,including electrical cooling devices,heat exchangers,radiators,and solar heaters.
基金Supported by the National Natural Science Foundation of China(12272248)。
文摘The stability of solutions of Herglotz-type equations for non-autonomous non-conservative systems is studied by means of generalized gradient method.Firstly,Herglotz-type equations for non-conservative systems are given and expressed as contravariant algebraic form.Secondly,two classes of generalized gradient systems are introduced.Thirdly,the conditions for the transformation of Herglotz-type equations into generalized gradient systems are given,and the solutions of Herglotz-type equations and the stability of the solutions are analyzed.Finally,for each case discussed in this paper,the calculation process is demonstrated in detail to show that the method is effective.
基金supported by the Fundamental Research Funds of Chinese Academy of Forestry(Nos.CAFYBB2022SY037,CAFYBB2021ZA002 and CAFYBB2022QC002)the Basic Research Foundation of Yunnan Province(Grant No.202201AT070264).
文摘Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.
基金Project supported by the National Natural Science Foundation of China(Nos.52241103 and 52322505)the Natural Science Foundation of Hunan Province of China(No.2023JJ10055)。
文摘An analytical method is proposed with the “stiffness gradient of the response” as a sensitivity metric, and the relationships between the vibration responses and stiffness changes are established. First, a 2-degree-of-freedom (DOF) system is used as an example to propose a stiffness gradient-based evaluation method, taking the effective control bandwidth ratio as a metric of effectiveness. The results show that there is an optimal mass ratio in both variable mass and variable stiffness cases. Then, a typical 16-DOF system is used to investigate the frequency domain characteristics of the stiffness gradient values in the complex system. The distributions of stiffness gradient values show multiple peak intervals corresponding to the sensitive regions for vibration control. By assigning random mass parameters, a significant exponential decay relationship between the subsystem’s mass and effective control is identified, emphasizing the importance of the optimal mass ratio. The finite-element simulation results of solid plate models with springs and oscillators further validate the theoretical results. In short, the gradient value of stiffness effectively quantifies the effects of subsystems on vibration control, providing an analytical tool for active control in complex systems. The identified exponential decay relationship offers meaningful guidance for implementation strategies.
基金supported by the National Natural Science Foundation of China(42201281,42471320 and 42407652)the Natural Science Foundation of Anhui Province,China(2208085QD102)。
文摘Changes in agricultural land use affect ecosystem services and their interactions.However,the differential influences of agricultural land use transitions under different topographical gradients on ecosystem service interactions remain poorly understood,which limits the integrated management of agricultural systems.The objectives of this study were to analyze the transitional trends of major agricultural land types across distinct topographical gradients and to probe the differential impacts of these transitions on ecosystem service interactions.Using Hangzhou of China as the study area,the analysis focused on four major agricultural land use types(arable land,orchard,tea garden,and abandoned land).The GTWR model was applied to investigate spatiotemporal non-stationarity in the impacts of their transitions on the ecosystem service trade-offs and synergies.The results showed that during 2010–2020,the agricultural land use pattern in plain areas became more diversified and fragmented,while it shifted towards greater homogeneity and contiguity in hilly and mountainous areas.Between 2010–2015 and 2015–2020,the dominant output type of agricultural land use transition was arable land.The dominant input type in plain areas shifted from arable land to orchard,whereas in hilly and mountainous areas,it was orchard and tea garden.The higher synergy between habitat quality and other ecosystem services primarily occurred in plain areas.Over time,the higher synergy between carbon sequestration and soil retention predominantly shifted from mountainous areas to plain areas.A variety of abandoned types across different topographical gradients fostered synergies by reducing the supply capacity of various ecosystem services.Trade-offs between ecosystem services in hilly and mountainous areas could be alleviated by converting arable land into orchard and tea garden.These findings highlight the importance of adopting differentiated,dynamic,and systematic measures for agricultural spatial development in implementing ecosystem management across different topographical gradients.
基金supported by Culture,Sports and Tourism R&D Program through the Korea Creative Content Agency grant funded by the Ministry of Culture,Sports and Tourism in 2024(Project Name:Global Talent Training Program for Copyright Management Technology in Game Contents,Project Number:RS-2024-00396709,Contribution Rate:100%).
文摘Cyber-physical systems(CPS)represent a sophisticated integration of computational and physical components that power critical applications such as smart manufacturing,healthcare,and autonomous infrastructure.However,their extensive reliance on internet connectivity makes them increasingly susceptible to cyber threats,potentially leading to operational failures and data breaches.Furthermore,CPS faces significant threats related to unauthorized access,improper management,and tampering of the content it generates.In this paper,we propose an intrusion detection system(IDS)optimized for CPS environments using a hybrid approach by combining a natureinspired feature selection scheme,such as Grey Wolf Optimization(GWO),in connection with the emerging Light Gradient Boosting Machine(LightGBM)classifier,named as GWO-LightGBM.While gradient boosting methods have been explored in prior IDS research,our novelty lies in proposing a hybrid approach targeting CPS-specific operational constraints,such as low-latency response and accurate detection of rare and critical attack types.We evaluate GWO-LightGBM against GWO-XGBoost,GWO-CatBoost,and an artificial neural network(ANN)baseline using the NSL-KDD and CIC-IDS-2017 benchmark datasets.The proposed models are assessed across multiple metrics,including accuracy,precision,recall,and F1-score,with an emphasis on class-wise performance and training efficiency.The proposed GWO-LightGBM model achieves the highest overall accuracy(99.73%)for NSL-KDD and(99.61%)for CIC-IDS-2017,demonstrating superior performance in detecting minority classes such as Remote-to-Local(R2L)and Other attacks—commonly overlooked by other classifiers.Moreover,the proposed model consumes lower training time,highlighting its practical feasibility and scalability for real-time CPS deployment.
基金National Defense Basic Scientific Research Program of China(JCKY2020408B002,WDZC2022-12)Key Research and Development Program of Shanxi Province(202102050201011,202202050201014)Fundamental Research Program of Shanxi Province(20210302124178,20210302123061,202103021224183)。
文摘A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element simulation.The analysis was verified by an impact experiment.Results show that the high-level thickness and appropriate percentage of Ti alloy at the upper side of the gradient structure provide greater impact resistance against the bullet,which increases the warhead breakage and enhances the anti-penetration performance.In addition,during the impact process,the stress is transmitted and reflected in the form of waves in each layer of the target plate,and the interaction between the compression and tension waves causes non-synergistic deformation of the target plate and leads to delamination.The gradient target plate takes penetration resistance a step further through the higher energy absorption rate and more consumption of the bullet kinetic energy.This research provides a theoretical basis for the application of gradient structures in metallic laminated armor.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274313 and 62375234)the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship (Grant No.ZXL2024400)。
文摘Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.
基金supported by the National Key Research and Development Program of China(2023YFB3809300).
文摘Recycling spent lithium-ion(Li+)batteries is critical for achieving environmental conservation and the strategic recovery of essential resources.Compared with conventional methods for recovering cathode materials,which are energy-intensive and prone to secondary pollution,the direct regeneration approach has emerged as a rapid and highly efficient method,gaining widespread attention in recent years.However,this approach faces major challenges,including degraded electrochemical performances and limited economic value.This study,therefore,proposes a high-value direct regeneration strategy to convert degraded spent LiFePO_(4)(S-LFP)into a gradient manganese(Mn)-doped regenerated LiFe_(0.7)Mn_(0.3)PO_(4)/C(R-LFMP)composite.This method leverages the inherent microcracks and Li vacancies present in S-LFP,likely acting as diffusion channels for the Mn^(2+)/Li^(+)ions.Through a two-step mechanochemical ball-milling and carbothermal reduction process,this approach achieves simultaneous Li replenishment and surface-localised Mn gradient doping with enhanced structural control.Notably,the R-LFMP exhibits an exceptional electrochemical performance.At 0.1 C,it delivers a discharge capacity of 161.4 mA h g^(−1)and an energy density of 563.5 Wh kg^(−1)(representing a 60.5%improvement over S-LFP).Additionally,it maintains 83%capacity retention after 900 cycles at 0.5C,a considerable enhancement compared to commercial LFMP(62%).Furthermore,the regenerated cathode material generates a net profit of$7.102 kg^(−1),surpassing the profitability of conventional recycling methods by 90%.Overall,this study introduces a transformative and sustainable LFP regeneration technology,achieving breakthroughs in electrochemical restoration and high-value recycling,while paving the way for the closed-loop utilisation of LFP-based energy storage systems.
基金supported by grants from the National Natural Science Foundation of China(Grant No.32360333)the Guizhou Provincial Science and Technology Projects(Grant Nos.ZK[2022]540 and[2023]099)+1 种基金the Survey of Amphibian and Reptile Resources in Leigongshan National Nature Reserve and Literature Publishing Services(P5226002023000019)the Guizhou Provincial Science and Technology Innovation Talent Team Construction Project 2024[Qian Ke He Talent CXTD(2025)053].
文摘Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fosters centers of endemism,and they harbor over 85%of global species diversity(Zhao et al.,2022).Consequently,mountains are key systems for exploring biodiversity patterns along elevational gradients,where species richness often follows four recognized models:monotonic decrease,unimodal pattern(forward and backward peak patterns),and low plateau followed by a decrease along the elevational gradient(McCain et al.,2010).
基金supported by the National Research Foundation of Korea(NRF)grants(Grant Nos.RS-2020-NR049594 and RS-2022-NR071877)the Korea Agency for Infrastructure Technology Advancement under the Ministry of Land,Infrastructure and Transport(Grant No.RS-2024-00410248).
文摘Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensional soil column experiments under a stepwise increase in hydraulic gradient(i),aiming to evaluate the critical hydraulic gradient(icrit)as a function of the size ratio between sand and clay,clay type,and ionic concentration.It was found that icrit was less than 0.1 for all sand-clay mixtures examined in this study.In addition,the lower peak concentrations of filtrated clay observed in sand-illite mixtures,compared to those of sand-kaolinite mixtures at the same level of i,suggest that illite particles are more susceptible to suffusion.Overall,the observed breakthrough curves,mass fraction of filtrated clay,volume of outflow,and total injection time presented in this study highlight the importance of considering clay type,sand-to-clay size ratio,and ionic concentration when assessing the suffusion behavior of clay-containing soils under a stepwise increase in hydraulic gradient.
文摘Transformer models face significant computational challenges in private inference(PI).Existing optimization methods often rely on isolated techniques,neglecting joint structural and operational improvements.We propose IG-3D,a unified framework that integrates structured compression and operator approximation through accurate importance assessment.Our approach first evaluates attention head importance using Integrated Gradients(IG),offering greater stability and theoretical soundness than gradient-based methods.We then apply a threedimensional optimization:(1)structurally pruning redundant attention heads;(2)replacing Softmax with adaptive polynomial approximation to avoid exponential computations;(3)implementing layer-wise GELU substitution to accommodate different layer characteristics.A joint thresholdmechanism coordinates compression across dimensions under accuracy constraints.Experimental results on the GLUE benchmark show that our method achieves an average 2.9×speedup in inference latency and a 50%reduction in communication cost,while controlling the accuracy loss within 2.3%,demonstrating significant synergistic effects and a superior accuracy-efficiency trade-off compared to single-technique optimization strategies.
基金supported by Natural Science Foundation of Xiamen,China(No.3502Z20227232)the STS Project of Fujian-CAS(No.2023T3018)Bureau of International Cooperation,Chinese Academy of Sciences(No.322GJHZ2022035MI).
文摘Anammox bacteria in constructed wetlands(CWs)play pivotal role in sustainable nitrogen transformation,yet existing studies lack comprehensive analysis of environmental gradients and microbial interactions,both key factors in anammox bacteria enrichment.This study investigated the mechanisms driving anammox bacteria enrichment in lab-scale simulated CWs treating high-nitrogen wastewater,focusing on bacterial community re-sponses across wetland layers with various strategies,including continuous up-flow influent,nitrogen loading increase,effluent recirculation,intermittent influent,and anammox bacteria inoculation.Results showed that total relative and absolute abundances of anammox bacteria ranged from 0.77%to 12.50%and from 0.13 to 6.46×10^(7) copies/g,respectively.Dissolved oxygen and pH had significant positive correlations with the absolute abundance of anammox bacteria,while organic matter and nitrate negatively impacted their relative abundance.Permutational multivariate analysis of variance indicated that spatial heterogeneity explained more variation in anammox bacteria abundance(43.44%)compared to operational strategies(8.58%).In terms of microbial interactions,60 dominant species exhibited potential correlations with anammox bacteria,comprising 170 interactions(105 positive and 65 negative),which suggested that anammox bacteria generally foster cooperative relationships with dominant bacteria.Notably,significant interspecies interactions were observed between Candidatus Kuenenia(dominant anammox bacteria in CWs)and species within the genera Chitinivibrio-nia and Anaerolineaceae,suggesting that microbial interactions primarily manifest as indirect facilitative effects rather than direct mutualistic relationships.Given that the Normalized Stochasticity Ratio in CWs were<50%,this study inferred that environmental gradients have greater influence on anammox bacteria than microbial interactions.
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.
