A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equati...A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column). Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.展开更多
The plastic deformation behavior of new Mg-Gd-Y-Zn-Mn magnesium alloys gains great necessity to clarify and understand the mechanism deeply. In the present work,the tensile mechanical property test and visco-plastic s...The plastic deformation behavior of new Mg-Gd-Y-Zn-Mn magnesium alloys gains great necessity to clarify and understand the mechanism deeply. In the present work,the tensile mechanical property test and visco-plastic self-consistent (VPSC) model are used to investigate the activities of deformation modes of VW84M and VW94M magnesium alloys during the tensile deformation. The results show that the mechanical properties of the above extruded alloys are similar but VW94M has higher strength than VW84M after the same aging process. Compared with the extruded alloys,the as-aged alloys have significantly higher activation of pyramidal slip at the later stage of plastic deformation. In addition,the as-aged VW94M alloy with higher strength has the largest activity of pyramidal slip. In summary,the addition of Gd increases the critical resolved shear stress (CRSS)in each slip system of VW94M,while the increase in the strength and the decrease in the elongation of as-aged alloys are associated with the significant activation of pyramidal slip.展开更多
The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical...The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical monopole plasma antenna excited by surface wave;calculation of the model is based on Maxwell-Boltzmann equation and gas molecular dynamics theory. The calculation results show that this method can reflect the relationships between the external excitation power, gas pressure, discharge current and the characteristic of plasma. It is an accurate method to predicate and calculate the parameters of plasma antenna.展开更多
In this work,the evolutions of stresses in both phases of the Al/SiCp composite subjected to thermal cycling during in situ compression test were measured using Time of Flight neutron diffraction.It was confirmed that...In this work,the evolutions of stresses in both phases of the Al/SiCp composite subjected to thermal cycling during in situ compression test were measured using Time of Flight neutron diffraction.It was confirmed that inter-phase stresses in the studied composite can be caused by differences in the coefficient of thermal expansion for the reinforcement and matrix,leading to a different variation of phase volumes during sample heating or cooling.The results of the diffraction experiment during thermal cycling were well predicted by the Thermo-Mechanical Self-Consistent model.The experimental study of elastic-plastic deformation was carried out in situ on a unique diffractometer EPSILON-MDS(JINR in Dubna,Russia)with nine detector banks measuring interplanar spacings simultaneously in 9 orientations of scattering vector.For the first time,the performed analysis of experimental data allowed to study the evolution of full stress tensor in both phases of the composite and to consider the decomposition of this tensor into deviatoric and hydrostatic components.It was found that the novel Developed Thermo-Mechanical SelfConsistent model correctly predicted stress evolution during compressive loading,taking into account the relaxation of thermal origin hydrostatic stresses.The comparison of this model with experimental data at the macroscopic level and the level of phases showed that strengthening of the Al/SiCp composite is caused by stress transfer from the plastically deformed A12124 matrix to the elastic SiCp reinforcement,while thermal stresses relaxation does not significantly affect the overall composite properties.展开更多
An integrated calculated approach based on weakly coupled finite element(FEM)-viscoplastic selfconsistent(VPSC)model was established to simulate the texture evolution during the variable strain path extrusion process ...An integrated calculated approach based on weakly coupled finite element(FEM)-viscoplastic selfconsistent(VPSC)model was established to simulate the texture evolution during the variable strain path extrusion process of magnesium alloys.The spiral die extrusion(SDE)process with additional circumferential shear deformation was applied to investigate the effect of path control on texture adjustment and verify the accuracy of the model.The results indicated that the additional spiral shear resulting from the overall inclined flow path effectively reduced the intensity of the{0002}//ED fiber texture by suppressing basal slip activation in the core area,while the local shear deformation along the spiral equal channel strain path led to the formation of an inclined{0002}//ND plane texture on the side.Using the modified Hall-Petch relationship,the correlation between texture and yield strength was quantified.Specifically,the weakening of the texture effectively suppressed{10-12}tensile twinning,which compensated for the deficiency of compressive yield strength without significantly sacrificing tensile yield strength,and thus improved the tension-compression asymmetry.Furthermore,the strongly inclined{0002}//ND plane texture inhibited the widespread activation of basal slip during tensile yielding,thereby enhancing the yield strength.展开更多
A 1D radially self-consistent model in helicon plasmas has been established to investigate the influence of radial heat conduction on plasma transport and wave propagation.Two kinds of 1D radial fluid models,with and ...A 1D radially self-consistent model in helicon plasmas has been established to investigate the influence of radial heat conduction on plasma transport and wave propagation.Two kinds of 1D radial fluid models,with and without considering heat conduction,have been developed to couple the 1D plasma-wave interaction model,and self-consistent solutions have been obtained.It is concluded that in the low magnetic field range the radial heat conduction plays a moderate role in the transport of helicon plasmas and the importance depends on the application of the helicon source.It influences the local energy balance leading to enhancement of the electron temperature in the bulk region and a decrease in plasma density.The power deposition in the plasma is mainly balanced by collisional processes and axial diffusion,whereas it is compensated by heat conduction in the bulk region and consumed near the boundary.The role of radial heat conduction in the large magnetic field regime becomes negligible and the two fluid models show consistency.The local power balance,especially near the wall,is improved when conductive heat is taken into account.展开更多
A self-consistent and three-dimensional （3D） model of argon discharge in a large-scale rectangular surface-wave plasma （SWP） source is presented in this paper, which is based on the finite-difference time-domain ...A self-consistent and three-dimensional （3D） model of argon discharge in a large-scale rectangular surface-wave plasma （SWP） source is presented in this paper, which is based on the finite-difference time-domain （FDTD） approximation to Maxwell＇s equations self-consistently coupled with a fluid model for plasma evolution. The discharge characteristics at an input microwave power of 1200 W and a filling gas pressure of 50 Pa in the SWP source are analyzed. The simulation shows the time evolution of deposited power density at different stages, and the 3D distributions of electron density and temperature in the chamber at steady state. In addition, the results show that there is a peak of plasma density approximately at a vertical distance of 3 cm from the quartz window.展开更多
The fully self-consistent model of modern semiconductor lasers used to design their advanced structures and to understand more deeply their properties is given in the present paper. Operation of semiconductor lasers d...The fully self-consistent model of modern semiconductor lasers used to design their advanced structures and to understand more deeply their properties is given in the present paper. Operation of semiconductor lasers de- pends not only on many optical, electrical, thermal, recombination, and sometimes mechanical phenomena taking place within their volumes but also on numerous mutual interactions between these phenomena. Their experimental investigation is quite complex, mostly because of miniature device sizes. Therefore, the most convenient and exact method to analyze expected laser operation and to determine laser optimal structures for various applications is to examine the details of their performance with the aid of a simulation of laser operation in various considered condi- tions. Such a simulation of an operation of semiconductor lasers is presented in this paper in a full complexity of all mutual interactions between the above individual physical processes. In particular, the hole-buming effect has been discussed. The impacts on laser performance introduced by oxide apertures （their sizes and localization） have been analyzed in detail. Also, some important details concerning the operation of various types of semiconductor lasers are discussed. The results of some applications of semiconductor lasers are shown for successive laser structures.展开更多
This work investigates the effects of deformation mechanisms on the mechanical properties and anisotropy of rolled AZ31B magnesium alloy under uniaxial tension,combining experimental characterization with Visco-Plasti...This work investigates the effects of deformation mechanisms on the mechanical properties and anisotropy of rolled AZ31B magnesium alloy under uniaxial tension,combining experimental characterization with Visco-Plastic Self Consistent(VPSC)modeling.The research focuses particularly on anisotropic mechanical responses along transverse direction(TD)and rolling direction(RD).Experimental measurements and computational simulations consistently demonstrate that prismaticslip activation significantly reduces the strain hardening rate during the initial stage of tensile deformation.By suppressing the activation of specific deformation mechanisms along RD and TD,the tensile mechanical behavior of the magnesium alloy was further investigated.The results show that basalslip has the greatest impact during the initial deformation stage and basalslip activation substantially affects the deformation behavior of AZ31B alloy,causing marked decreases in both yield and tensile strength along RD.Under tensile loading along TD,prismaticslip not only exhibits a synergistic effect on yield strength,but also dominants work hardening during the initial plastic deformation.展开更多
In this study,we investigate the ef-ficacy of a hybrid parallel algo-rithm aiming at enhancing the speed of evaluation of two-electron repulsion integrals(ERI)and Fock matrix generation on the Hygon C86/DCU(deep compu...In this study,we investigate the ef-ficacy of a hybrid parallel algo-rithm aiming at enhancing the speed of evaluation of two-electron repulsion integrals(ERI)and Fock matrix generation on the Hygon C86/DCU(deep computing unit)heterogeneous computing platform.Multiple hybrid parallel schemes are assessed using a range of model systems,including those with up to 1200 atoms and 10000 basis func-tions.The findings of our research reveal that,during Hartree-Fock(HF)calculations,a single DCU ex-hibits 33.6 speedups over 32 C86 CPU cores.Compared with the efficiency of Wuhan Electronic Structure Package on Intel X86 and NVIDIA A100 computing platform,the Hygon platform exhibits good cost-effective-ness,showing great potential in quantum chemistry calculation and other high-performance scientific computations.展开更多
A model of scrape-off layer （SOL）-plasma surface interaction （PSI） coupling is pre- sented for divertor operation. This model can treat the interrelation between impurity production and impurity radiation self-con...A model of scrape-off layer （SOL）-plasma surface interaction （PSI） coupling is pre- sented for divertor operation. This model can treat the interrelation between impurity production and impurity radiation self-consistently. The model is based on a ＇two-point＇ model and a 0-D steady state impurity particle balance model. The fraction of power radiated in SOL is calcu- lated as a function of the line average density. Compared to the former simple coupling model, this model takes into account the wall-produced impurities that are sputtered by charge-exchange （CX） neutrals. A simple retention factor is also added in this model. A comparison with the experiments is made. The simulation results show the same trend upon the plasma density as shown in experiments. Reasonable qualitative agreement is reached between the results by using the model and those from experiments through the adjustment of the fitted factor.展开更多
Model evaluation using benchmark datasets is an important method to measure the capability of large language models(LLMs)in specific domains,and it is mainly used to assess the knowledge and reasoning abilities of LLM...Model evaluation using benchmark datasets is an important method to measure the capability of large language models(LLMs)in specific domains,and it is mainly used to assess the knowledge and reasoning abilities of LLMs.Therefore,in order to better assess the capability of LLMs in the agricultural domain,Agri-Eval was proposed as a benchmark for assessing the knowledge and reasoning ability of LLMs in agriculture.The assessment dataset used in Agri-Eval covered seven major disciplines in the agricultural domain:crop science,horticulture,plant protection,animal husbandry,forest science,aquaculture science,and grass science,and contained a total of 2283 questions.Among domestic general-purpose LLMs,DeepSeek R1 performed best with an accuracy rate of 75.49%.In the realm of international general-purpose LLMs,Gemini 2.0 pro exp 0205 standed out as the top performer,achieving an accuracy rate of 74.28%.As an LLMs in agriculture vertical,Shennong V2.0 outperformed all the LLMs in China,and the answer accuracy rate of agricultural knowledge exceeded that of all the existing general-purpose LLMs.The launch of Agri-Eval helped the LLM developers to comprehensively evaluate the model's capability in the field of agriculture through a variety of tasks and tests to promote the development of the LLMs in the field of agriculture.展开更多
In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asy...In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asymptotic stability of the trivial solution and the positive periodic solution.Finally,numerical simulations are presented to validate our results.Our results show that age-selective harvesting is more conducive to sustainable population survival than non-age-selective harvesting.展开更多
In their recent paper Pereira et al.(2025)claim that validation is overlooked in mapping and modelling of ecosystem services(ES).They state that“many studies lack critical evaluation of the results and no validation ...In their recent paper Pereira et al.(2025)claim that validation is overlooked in mapping and modelling of ecosystem services(ES).They state that“many studies lack critical evaluation of the results and no validation is provided”and that“the validation step is largely overlooked”.This assertion may have been true several years ago,for example,when Ochoa and Urbina-Cardona(2017)made a similar observation.However,there has been much work on ES model validation over the last decade.展开更多
In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and cha...In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.展开更多
The Reynolds-averaged Navier-Stokes(RANS)technique enables critical engineering predictions and is widely adopted.However,since this iterative computation relies on the fixed-point iteration,it may converge to unexpec...The Reynolds-averaged Navier-Stokes(RANS)technique enables critical engineering predictions and is widely adopted.However,since this iterative computation relies on the fixed-point iteration,it may converge to unexpected non-physical phase points in practice.We conduct an analysis on the phase-space characteristics and the fixed-point theory underlying the k-ε turbulence model,and employ the classical Kolmogorov flow as a framework,leveraging its direct numerical simulation(DNS)data to construct a one-dimensional(1D)system under periodic/fixed boundary conditions.The RANS results demonstrate that under periodic boundary conditions,the k-ε model exhibits only a unique trivial fixed point,with asymptotes capturing the phase portraits.The stability of this trivial fixed point is determined by a mathematically derived stability phase diagram,indicating the fact that the k-ε model will never converge to correct values under periodic conditions.In contrast,under fixed boundary conditions,the model can yield a stable non-trivial fixed point.The evolutionary mechanisms and their relationship with boundary condition settings systematically explain the inherent limitations of the k-ε model,i.e.,its deficiency in computing the flow field under periodic boundary conditions and sensitivity to boundary-value specifications under fixed boundary conditions.These conclusions are finally validated with the open-source code OpenFOAM.展开更多
Utilizing finite element analysis,the ballistic protection provided by a combination of perforated D-shaped and base armor plates,collectively referred to as radiator armor,is evaluated.ANSYS Explicit Dynamics is empl...Utilizing finite element analysis,the ballistic protection provided by a combination of perforated D-shaped and base armor plates,collectively referred to as radiator armor,is evaluated.ANSYS Explicit Dynamics is employed to simulate the ballistic impact of 7.62 mm armor-piercing projectiles on Aluminum AA5083-H116 and Steel Secure 500 armors,focusing on the evaluation of material deformation and penetration resistance at varying impact points.While the D-shaped armor plate is penetrated by the armor-piercing projectiles,the combination of the perforated D-shaped and base armor plates successfully halts penetration.A numerical model based on the finite element method is developed using software such as SolidWorks and ANSYS to analyze the interaction between radiator armor and bullet.The perforated design of radiator armor is to maintain airflow for radiator function,with hole sizes smaller than the bullet core diameter to protect radiator assemblies.Predictions are made regarding the brittle fracture resulting from the projectile core′s bending due to asymmetric impact,and the resulting fragments failed to penetrate the perforated base armor plate.Craters are formed on the surface of the perforated D-shaped armor plate due to the impact of projectile fragments.The numerical model accurately predicts hole growth and projectile penetration upon impact with the armor,demonstrating effective protection of the radiator assemblies by the radiator armor.展开更多
Recommendation systems are key to boosting user engagement,satisfaction,and retention,particularly on media platforms where personalized content is vital.Sequential recommendation systems learn from user-item interact...Recommendation systems are key to boosting user engagement,satisfaction,and retention,particularly on media platforms where personalized content is vital.Sequential recommendation systems learn from user-item interactions to predict future items of interest.However,many current methods rely on unique user and item IDs,limiting their ability to represent users and items effectively,especially in zero-shot learning scenarios where training data is scarce.With the rapid development of Large Language Models(LLMs),researchers are exploring their potential to enhance recommendation systems.However,there is a semantic gap between the linguistic semantics of LLMs and the collaborative semantics of recommendation systems,where items are typically indexed by IDs.Moreover,most research focuses on item representations,neglecting personalized user modeling.To address these issues,we propose a sequential recommendation framework using LLMs,called CIT-Rec,a model that integrates Collaborative semantics for user representation and Image and Text information for item representation to enhance Recommendations.Specifically,by aligning intuitive image information with text containing semantic features,we can more accurately represent items,improving item representation quality.We focus not only on item representations but also on user representations.To more precisely capture users’personalized preferences,we use traditional sequential recommendation models to train on users’historical interaction data,effectively capturing behavioral patterns.Finally,by combining LLMs and traditional sequential recommendation models,we allow the LLM to understand linguistic semantics while capturing collaborative semantics.Extensive evaluations on real-world datasets show that our model outperforms baseline methods,effectively combining user interaction history with item visual and textual modalities to provide personalized recommendations.展开更多
The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-bas...The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.展开更多
(Quasi-)closed-form results for the statistical properties of unmanned aerial vehicle(UAV)airto-ground channels are derived for the first time using a novel spatial-vector-based method from a threedimensional(3-D)arbi...(Quasi-)closed-form results for the statistical properties of unmanned aerial vehicle(UAV)airto-ground channels are derived for the first time using a novel spatial-vector-based method from a threedimensional(3-D)arbitrary-elevation one-cylinder model.The derived results include a closed-form expression for the space-time correlation function and some quasi-closed-form ones for the space-Doppler power spectrum density,the level crossing rate,and the average fading duration,which are shown to be the generalizations of those previously obtained from the two-dimensional(2-D)one-ring model and the 3-D low-elevation one-cylinder model for terrestrial mobile-to-mobile channels.The close agreements between the theoretical results and the simulations as well as the measurements validate the utility of the derived channel statistics.Based on the derived expressions,the impacts of some parameters on the channel characteristics are investigated in an effective,efficient,and explicable way,which leads to a general guideline on the manual parameter estimation from the measurement description.展开更多
基金The project supported by the National Nature Science Foundation of China (No. 10275010)
文摘A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column). Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.
文摘The plastic deformation behavior of new Mg-Gd-Y-Zn-Mn magnesium alloys gains great necessity to clarify and understand the mechanism deeply. In the present work,the tensile mechanical property test and visco-plastic self-consistent (VPSC) model are used to investigate the activities of deformation modes of VW84M and VW94M magnesium alloys during the tensile deformation. The results show that the mechanical properties of the above extruded alloys are similar but VW94M has higher strength than VW84M after the same aging process. Compared with the extruded alloys,the as-aged alloys have significantly higher activation of pyramidal slip at the later stage of plastic deformation. In addition,the as-aged VW94M alloy with higher strength has the largest activity of pyramidal slip. In summary,the addition of Gd increases the critical resolved shear stress (CRSS)in each slip system of VW94M,while the increase in the strength and the decrease in the elongation of as-aged alloys are associated with the significant activation of pyramidal slip.
文摘The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical monopole plasma antenna excited by surface wave;calculation of the model is based on Maxwell-Boltzmann equation and gas molecular dynamics theory. The calculation results show that this method can reflect the relationships between the external excitation power, gas pressure, discharge current and the characteristic of plasma. It is an accurate method to predicate and calculate the parameters of plasma antenna.
基金supported by grants from the National Science Centre,Poland(NCN)No.UMO-2017/25/B/ST8/00134 and UMO2015/19/D/ST8/00818supported by the Polish-JINR Programme 2017(item 24)supported by the Federal Ministry for Education and Research in Germany。
文摘In this work,the evolutions of stresses in both phases of the Al/SiCp composite subjected to thermal cycling during in situ compression test were measured using Time of Flight neutron diffraction.It was confirmed that inter-phase stresses in the studied composite can be caused by differences in the coefficient of thermal expansion for the reinforcement and matrix,leading to a different variation of phase volumes during sample heating or cooling.The results of the diffraction experiment during thermal cycling were well predicted by the Thermo-Mechanical Self-Consistent model.The experimental study of elastic-plastic deformation was carried out in situ on a unique diffractometer EPSILON-MDS(JINR in Dubna,Russia)with nine detector banks measuring interplanar spacings simultaneously in 9 orientations of scattering vector.For the first time,the performed analysis of experimental data allowed to study the evolution of full stress tensor in both phases of the composite and to consider the decomposition of this tensor into deviatoric and hydrostatic components.It was found that the novel Developed Thermo-Mechanical SelfConsistent model correctly predicted stress evolution during compressive loading,taking into account the relaxation of thermal origin hydrostatic stresses.The comparison of this model with experimental data at the macroscopic level and the level of phases showed that strengthening of the Al/SiCp composite is caused by stress transfer from the plastically deformed A12124 matrix to the elastic SiCp reinforcement,while thermal stresses relaxation does not significantly affect the overall composite properties.
基金supported by the National Natural Science Foundation of China(Grant Nos.51975146,52205344)Shandong Province Natural Science Foundation(Grant No.ZR2020QE171)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(Nos.NRF-2021R1A2C3006662,NRF-2022R1A5A1030054).
文摘An integrated calculated approach based on weakly coupled finite element(FEM)-viscoplastic selfconsistent(VPSC)model was established to simulate the texture evolution during the variable strain path extrusion process of magnesium alloys.The spiral die extrusion(SDE)process with additional circumferential shear deformation was applied to investigate the effect of path control on texture adjustment and verify the accuracy of the model.The results indicated that the additional spiral shear resulting from the overall inclined flow path effectively reduced the intensity of the{0002}//ED fiber texture by suppressing basal slip activation in the core area,while the local shear deformation along the spiral equal channel strain path led to the formation of an inclined{0002}//ND plane texture on the side.Using the modified Hall-Petch relationship,the correlation between texture and yield strength was quantified.Specifically,the weakening of the texture effectively suppressed{10-12}tensile twinning,which compensated for the deficiency of compressive yield strength without significantly sacrificing tensile yield strength,and thus improved the tension-compression asymmetry.Furthermore,the strongly inclined{0002}//ND plane texture inhibited the widespread activation of basal slip during tensile yielding,thereby enhancing the yield strength.
基金National Natural Science Foundation of China(No.51907039)Shenzhen Technology Project(Nos.JCYJ20190806142603534 and ZDSYS201707280904031)+1 种基金ESPEOS project(No.PID2019108034RB-I00/AEI/10.13039/501100011033)funded by the Agencia Estatal de Investigacion(Spanish National Research Agency)。
文摘A 1D radially self-consistent model in helicon plasmas has been established to investigate the influence of radial heat conduction on plasma transport and wave propagation.Two kinds of 1D radial fluid models,with and without considering heat conduction,have been developed to couple the 1D plasma-wave interaction model,and self-consistent solutions have been obtained.It is concluded that in the low magnetic field range the radial heat conduction plays a moderate role in the transport of helicon plasmas and the importance depends on the application of the helicon source.It influences the local energy balance leading to enhancement of the electron temperature in the bulk region and a decrease in plasma density.The power deposition in the plasma is mainly balanced by collisional processes and axial diffusion,whereas it is compensated by heat conduction in the bulk region and consumed near the boundary.The role of radial heat conduction in the large magnetic field regime becomes negligible and the two fluid models show consistency.The local power balance,especially near the wall,is improved when conductive heat is taken into account.
基金Project supported by the Special Fund of National High-Tech Development and Research Plan (Grant No 2008AA12A214)
文摘A self-consistent and three-dimensional （3D） model of argon discharge in a large-scale rectangular surface-wave plasma （SWP） source is presented in this paper, which is based on the finite-difference time-domain （FDTD） approximation to Maxwell＇s equations self-consistently coupled with a fluid model for plasma evolution. The discharge characteristics at an input microwave power of 1200 W and a filling gas pressure of 50 Pa in the SWP source are analyzed. The simulation shows the time evolution of deposited power density at different stages, and the 3D distributions of electron density and temperature in the chamber at steady state. In addition, the results show that there is a peak of plasma density approximately at a vertical distance of 3 cm from the quartz window.
基金the partial support from the Polish National Science Centre (2014/13/B/ST7/00633)
文摘The fully self-consistent model of modern semiconductor lasers used to design their advanced structures and to understand more deeply their properties is given in the present paper. Operation of semiconductor lasers de- pends not only on many optical, electrical, thermal, recombination, and sometimes mechanical phenomena taking place within their volumes but also on numerous mutual interactions between these phenomena. Their experimental investigation is quite complex, mostly because of miniature device sizes. Therefore, the most convenient and exact method to analyze expected laser operation and to determine laser optimal structures for various applications is to examine the details of their performance with the aid of a simulation of laser operation in various considered condi- tions. Such a simulation of an operation of semiconductor lasers is presented in this paper in a full complexity of all mutual interactions between the above individual physical processes. In particular, the hole-buming effect has been discussed. The impacts on laser performance introduced by oxide apertures （their sizes and localization） have been analyzed in detail. Also, some important details concerning the operation of various types of semiconductor lasers are discussed. The results of some applications of semiconductor lasers are shown for successive laser structures.
基金supported by the National Nature Science Foundation of China(52275356).
文摘This work investigates the effects of deformation mechanisms on the mechanical properties and anisotropy of rolled AZ31B magnesium alloy under uniaxial tension,combining experimental characterization with Visco-Plastic Self Consistent(VPSC)modeling.The research focuses particularly on anisotropic mechanical responses along transverse direction(TD)and rolling direction(RD).Experimental measurements and computational simulations consistently demonstrate that prismaticslip activation significantly reduces the strain hardening rate during the initial stage of tensile deformation.By suppressing the activation of specific deformation mechanisms along RD and TD,the tensile mechanical behavior of the magnesium alloy was further investigated.The results show that basalslip has the greatest impact during the initial deformation stage and basalslip activation substantially affects the deformation behavior of AZ31B alloy,causing marked decreases in both yield and tensile strength along RD.Under tensile loading along TD,prismaticslip not only exhibits a synergistic effect on yield strength,but also dominants work hardening during the initial plastic deformation.
基金supported by the National Natural Science Foundation of China(No.22373112 to Ji Qi,No.22373111 and 21921004 to Minghui Yang)GH-fund A(No.202107011790)。
文摘In this study,we investigate the ef-ficacy of a hybrid parallel algo-rithm aiming at enhancing the speed of evaluation of two-electron repulsion integrals(ERI)and Fock matrix generation on the Hygon C86/DCU(deep computing unit)heterogeneous computing platform.Multiple hybrid parallel schemes are assessed using a range of model systems,including those with up to 1200 atoms and 10000 basis func-tions.The findings of our research reveal that,during Hartree-Fock(HF)calculations,a single DCU ex-hibits 33.6 speedups over 32 C86 CPU cores.Compared with the efficiency of Wuhan Electronic Structure Package on Intel X86 and NVIDIA A100 computing platform,the Hygon platform exhibits good cost-effective-ness,showing great potential in quantum chemistry calculation and other high-performance scientific computations.
基金supported by National Natural Science Foundation of China (No.10675192)
文摘A model of scrape-off layer （SOL）-plasma surface interaction （PSI） coupling is pre- sented for divertor operation. This model can treat the interrelation between impurity production and impurity radiation self-consistently. The model is based on a ＇two-point＇ model and a 0-D steady state impurity particle balance model. The fraction of power radiated in SOL is calcu- lated as a function of the line average density. Compared to the former simple coupling model, this model takes into account the wall-produced impurities that are sputtered by charge-exchange （CX） neutrals. A simple retention factor is also added in this model. A comparison with the experiments is made. The simulation results show the same trend upon the plasma density as shown in experiments. Reasonable qualitative agreement is reached between the results by using the model and those from experiments through the adjustment of the fitted factor.
文摘Model evaluation using benchmark datasets is an important method to measure the capability of large language models(LLMs)in specific domains,and it is mainly used to assess the knowledge and reasoning abilities of LLMs.Therefore,in order to better assess the capability of LLMs in the agricultural domain,Agri-Eval was proposed as a benchmark for assessing the knowledge and reasoning ability of LLMs in agriculture.The assessment dataset used in Agri-Eval covered seven major disciplines in the agricultural domain:crop science,horticulture,plant protection,animal husbandry,forest science,aquaculture science,and grass science,and contained a total of 2283 questions.Among domestic general-purpose LLMs,DeepSeek R1 performed best with an accuracy rate of 75.49%.In the realm of international general-purpose LLMs,Gemini 2.0 pro exp 0205 standed out as the top performer,achieving an accuracy rate of 74.28%.As an LLMs in agriculture vertical,Shennong V2.0 outperformed all the LLMs in China,and the answer accuracy rate of agricultural knowledge exceeded that of all the existing general-purpose LLMs.The launch of Agri-Eval helped the LLM developers to comprehensively evaluate the model's capability in the field of agriculture through a variety of tasks and tests to promote the development of the LLMs in the field of agriculture.
基金Supported by the National Natural Science Foundation of China(12261018)Universities Key Laboratory of Mathematical Modeling and Data Mining in Guizhou Province(2023013)。
文摘In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asymptotic stability of the trivial solution and the positive periodic solution.Finally,numerical simulations are presented to validate our results.Our results show that age-selective harvesting is more conducive to sustainable population survival than non-age-selective harvesting.
文摘In their recent paper Pereira et al.(2025)claim that validation is overlooked in mapping and modelling of ecosystem services(ES).They state that“many studies lack critical evaluation of the results and no validation is provided”and that“the validation step is largely overlooked”.This assertion may have been true several years ago,for example,when Ochoa and Urbina-Cardona(2017)made a similar observation.However,there has been much work on ES model validation over the last decade.
基金the World Climate Research Programme(WCRP),Climate Variability and Predictability(CLIVAR),and Global Energy and Water Exchanges(GEWEX)for facilitating the coordination of African monsoon researchsupport from the Center for Earth System Modeling,Analysis,and Data at the Pennsylvania State Universitythe support of the Office of Science of the U.S.Department of Energy Biological and Environmental Research as part of the Regional&Global Model Analysis(RGMA)program area。
文摘In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.
基金Project supported by the National Natural Science Foundation of China(Nos.12372214 and U2341231)。
文摘The Reynolds-averaged Navier-Stokes(RANS)technique enables critical engineering predictions and is widely adopted.However,since this iterative computation relies on the fixed-point iteration,it may converge to unexpected non-physical phase points in practice.We conduct an analysis on the phase-space characteristics and the fixed-point theory underlying the k-ε turbulence model,and employ the classical Kolmogorov flow as a framework,leveraging its direct numerical simulation(DNS)data to construct a one-dimensional(1D)system under periodic/fixed boundary conditions.The RANS results demonstrate that under periodic boundary conditions,the k-ε model exhibits only a unique trivial fixed point,with asymptotes capturing the phase portraits.The stability of this trivial fixed point is determined by a mathematically derived stability phase diagram,indicating the fact that the k-ε model will never converge to correct values under periodic conditions.In contrast,under fixed boundary conditions,the model can yield a stable non-trivial fixed point.The evolutionary mechanisms and their relationship with boundary condition settings systematically explain the inherent limitations of the k-ε model,i.e.,its deficiency in computing the flow field under periodic boundary conditions and sensitivity to boundary-value specifications under fixed boundary conditions.These conclusions are finally validated with the open-source code OpenFOAM.
文摘Utilizing finite element analysis,the ballistic protection provided by a combination of perforated D-shaped and base armor plates,collectively referred to as radiator armor,is evaluated.ANSYS Explicit Dynamics is employed to simulate the ballistic impact of 7.62 mm armor-piercing projectiles on Aluminum AA5083-H116 and Steel Secure 500 armors,focusing on the evaluation of material deformation and penetration resistance at varying impact points.While the D-shaped armor plate is penetrated by the armor-piercing projectiles,the combination of the perforated D-shaped and base armor plates successfully halts penetration.A numerical model based on the finite element method is developed using software such as SolidWorks and ANSYS to analyze the interaction between radiator armor and bullet.The perforated design of radiator armor is to maintain airflow for radiator function,with hole sizes smaller than the bullet core diameter to protect radiator assemblies.Predictions are made regarding the brittle fracture resulting from the projectile core′s bending due to asymmetric impact,and the resulting fragments failed to penetrate the perforated base armor plate.Craters are formed on the surface of the perforated D-shaped armor plate due to the impact of projectile fragments.The numerical model accurately predicts hole growth and projectile penetration upon impact with the armor,demonstrating effective protection of the radiator assemblies by the radiator armor.
基金supported by the National Key R&D Program of China[2022YFF0902703]the State Administration for Market Regulation Science and Technology Plan Project(2024MK033).
文摘Recommendation systems are key to boosting user engagement,satisfaction,and retention,particularly on media platforms where personalized content is vital.Sequential recommendation systems learn from user-item interactions to predict future items of interest.However,many current methods rely on unique user and item IDs,limiting their ability to represent users and items effectively,especially in zero-shot learning scenarios where training data is scarce.With the rapid development of Large Language Models(LLMs),researchers are exploring their potential to enhance recommendation systems.However,there is a semantic gap between the linguistic semantics of LLMs and the collaborative semantics of recommendation systems,where items are typically indexed by IDs.Moreover,most research focuses on item representations,neglecting personalized user modeling.To address these issues,we propose a sequential recommendation framework using LLMs,called CIT-Rec,a model that integrates Collaborative semantics for user representation and Image and Text information for item representation to enhance Recommendations.Specifically,by aligning intuitive image information with text containing semantic features,we can more accurately represent items,improving item representation quality.We focus not only on item representations but also on user representations.To more precisely capture users’personalized preferences,we use traditional sequential recommendation models to train on users’historical interaction data,effectively capturing behavioral patterns.Finally,by combining LLMs and traditional sequential recommendation models,we allow the LLM to understand linguistic semantics while capturing collaborative semantics.Extensive evaluations on real-world datasets show that our model outperforms baseline methods,effectively combining user interaction history with item visual and textual modalities to provide personalized recommendations.
基金supported by the CAS Pioneer Hundred Talents Program and Second Tibetan Plateau Scientific Expedition Research Program(2019QZKK0708)as well as the Basic Research Program of Qinghai Province:Lithospheric Geomagnetic Field of the Qinghai-Tibet Plateau and the Relationship with Strong Earthquakes(2021-ZJ-969Q).
文摘The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.
基金supported in part by the National Key Research and Development Program of China(2021YFB2900501)in part by the Shaanxi Science and Technology Innovation Team(2023-CX-TD-03)+3 种基金in part by the Science and Technology Program of Shaanxi Province(2021GXLH-Z-038)in part by the Natural Science Foundation of Hunan Province(2023JJ40607 and 2023JJ50045)in part by the Scientific Research Foundation of Hunan Provincial Education Department(23B0713 and 24B0603)in part by the National Natural Science Foundation of China(62401371,62101275,and 62372070).
文摘(Quasi-)closed-form results for the statistical properties of unmanned aerial vehicle(UAV)airto-ground channels are derived for the first time using a novel spatial-vector-based method from a threedimensional(3-D)arbitrary-elevation one-cylinder model.The derived results include a closed-form expression for the space-time correlation function and some quasi-closed-form ones for the space-Doppler power spectrum density,the level crossing rate,and the average fading duration,which are shown to be the generalizations of those previously obtained from the two-dimensional(2-D)one-ring model and the 3-D low-elevation one-cylinder model for terrestrial mobile-to-mobile channels.The close agreements between the theoretical results and the simulations as well as the measurements validate the utility of the derived channel statistics.Based on the derived expressions,the impacts of some parameters on the channel characteristics are investigated in an effective,efficient,and explicable way,which leads to a general guideline on the manual parameter estimation from the measurement description.
