The learning of English academic vocabulary has been the focus of numerous studies from the time Coxhead(2000)developed the academic word list to the present day.Various researchers have emphasized the importance of p...The learning of English academic vocabulary has been the focus of numerous studies from the time Coxhead(2000)developed the academic word list to the present day.Various researchers have emphasized the importance of possessing academic vocabulary knowledge for academic success.Recognizing this importance,it is crucial for researchers,teachers,and learners to understand the progress made in academic word lists.This systematic review first identifies,describes,appraises,and synthesizes the development of academic word lists from 2000 to 2020.It then examines the methods used by researchers in developing academic word lists among 56 studies that meet the pre-established criteria.The word lists were classified based on some criteria such as word counting units,corpora types/sizes,and exclusion criteria.Limitations,suggestions for further study,and implications are also discussed.Additionally,recommendations for future word list establishment are provided to help advance the field of word list development.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
Influenza,an acute respiratory infectious disease caused by the influenza virus,exhibits distinct seasonal patterns in China,with peak activity occurring in winter and spring in northern regions,and in winter and summ...Influenza,an acute respiratory infectious disease caused by the influenza virus,exhibits distinct seasonal patterns in China,with peak activity occurring in winter and spring in northern regions,and in winter and summer in southern areas[1].The World Health Organization(WHO)emphasizes that early warning and epidemic intensity assessments are critical public health strategies for influenza prevention and control.Internet-based flu surveillance,with real-time data and low costs,effectively complements traditional methods.The Baidu Search Index,which reflects flu-related queries,strongly correlates with influenza trends,aiding in regional activity assessment and outbreak tracking[2].展开更多
Convex feasibility problems are widely used in image reconstruction,sparse signal recovery,and other areas.This paper is devoted to considering a class of convex feasibility problem arising from sparse signal recovery...Convex feasibility problems are widely used in image reconstruction,sparse signal recovery,and other areas.This paper is devoted to considering a class of convex feasibility problem arising from sparse signal recovery.We rst derive the projection formulas for a vector onto the feasible sets.The centralized circumcentered-reection method is designed to solve the convex feasibility problem.Some numerical experiments demonstrate the feasibility and e ectiveness of the proposed algorithm,showing superior performance compared to conventional alternating projection methods.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
为揭示近断层地震动作用下岩质边坡的动态响应规律与灾变机制,提出了一种间接边界元法(indirect boundary element method,简称IBEM)与离散元法(discrete element method,简称DEM)耦合的时域分析体系,建立了考虑岩土体非连续变形特征的...为揭示近断层地震动作用下岩质边坡的动态响应规律与灾变机制,提出了一种间接边界元法(indirect boundary element method,简称IBEM)与离散元法(discrete element method,简称DEM)耦合的时域分析体系,建立了考虑岩土体非连续变形特征的近断层-边坡系统非线性动力响应模拟方法。首先基于IBEM构建半无限域千米级近断层地震波场高精度数值模型;其次,结合格林函数理论与IBEM求解波场,推导DEM计算域边界等效地震荷载的显式表达,进而实现IBEM-DEM耦合系统的跨尺度能量传递;最终通过DEM求解米级岩质边坡的非线性动力响应,实现了从千米级断层到米级边坡的多尺度非线性地震动模拟方法体系。数值模拟与动态监测结果表明:IBEM-DEM耦合算法可精准表征近场地震波传播的频散特性与能量衰减规律;近断层地震荷载作用下,软弱夹层首先发生渐进式剪切破坏,其强度劣化导致贯通性破裂面的形成,并引致滑体沿剪切面加速失稳,产生显著位移与速度响应,最终在坡脚形成典型碎屑堆积体;滑体表层速度显著高于底层,表层平均速度达到底层平均速度的3.6倍,其中滑体表层X向和Z向的速度分量峰值分别达到4.98 m/s和5.92 m/s,呈现出明显的趋表效应;滑体监测点从初始坡面位置到最终堆积体位置的X向和Z向最大位移分别可达41 m和35 m,时程表现出典型阶跃式增长特征,反映出滑体在动能与势能交替转换中的突跃式滑移行为。IBEM-DEM耦合方法构建了从岩体破裂到滑坡成灾的全过程演化序列,为近断层地震动诱发滑坡的动力灾变分析提供了创新性分析方法体系,并为复杂地质条件下滑坡机制的识别及地震灾害的防控提供了理论依据与技术支持。展开更多
The accurate measurement of the fill level in the ball mill has not been resolved because of the interplay of many variable factors, which led the mill to be operated under the uneconomical condition and lost a lot of...The accurate measurement of the fill level in the ball mill has not been resolved because of the interplay of many variable factors, which led the mill to be operated under the uneconomical condition and lost a lot of energy. At present, some methods, such as vibration method and acoustic method, have been applied for measuring the fill level by the researchers. Aiming at the problem of the traditional methods for measuring the fill level, that is, the feature variables of the fill level suffer the influences of the ball load and the water content of the coal, a novel method to measure the fill level is proposed and a possible relation between the fill level and the angular position of the maximum vibration point on the mill shell is investigated. The angular positions of the maximum vibration point on the mill shell for different fill level cases are calculated theoretically under two assumptions, respectively. Meanwhile the charge motions of the mill for different fill level cases are simulated with the discrete element method （DEM）. And the simulation results are verified by comparing the motion trajectories of steel balls and power draft of the mill. The simulated movement trajectories of the outmost layer steel balls in the mill are monitored and analyzed to obtain the angular positions of the maximum vibration point on the mill shell. Both the results of the theoretical calculation and the 3D DEM simulation show that the position of the maximum vibration point on the mill shell moves to a lower angular positions as the fill level decreasing, which provides a new idea for measuring the filllevel accurately.展开更多
Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environmen...Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.展开更多
Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal part...Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal particle was developed, and both contact force and gravity force were considered in the models. The simulation results were validated by our experiment. Three algorithms for representing an ellipsoidal particle were compared in macro and micro aspects. The results show that there exists big difference in the microscopic parameters such as kinetic energy, rotational kinetic energy, deformation, contact force and collision number which leads to the difference of macroscopic parameters. The relative error in the discharge rate and tracer particle position is the largest between 3-tangent-element representation and experimental results. The flow pattern is similar for the 5-element and 3-intersection representations. The only difference is the discharge rate of 5-element representation is larger than the experimental value and that of the 3-intersection representation has the contrary result. Finally the 3-intersection- element reoresentation is chosen in the simulation due to less comouting time than that of the 5-element renresentation.展开更多
文摘The learning of English academic vocabulary has been the focus of numerous studies from the time Coxhead(2000)developed the academic word list to the present day.Various researchers have emphasized the importance of possessing academic vocabulary knowledge for academic success.Recognizing this importance,it is crucial for researchers,teachers,and learners to understand the progress made in academic word lists.This systematic review first identifies,describes,appraises,and synthesizes the development of academic word lists from 2000 to 2020.It then examines the methods used by researchers in developing academic word lists among 56 studies that meet the pre-established criteria.The word lists were classified based on some criteria such as word counting units,corpora types/sizes,and exclusion criteria.Limitations,suggestions for further study,and implications are also discussed.Additionally,recommendations for future word list establishment are provided to help advance the field of word list development.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by the National Key Research and Development Program of China(Project No.2023YFC2307500).
文摘Influenza,an acute respiratory infectious disease caused by the influenza virus,exhibits distinct seasonal patterns in China,with peak activity occurring in winter and spring in northern regions,and in winter and summer in southern areas[1].The World Health Organization(WHO)emphasizes that early warning and epidemic intensity assessments are critical public health strategies for influenza prevention and control.Internet-based flu surveillance,with real-time data and low costs,effectively complements traditional methods.The Baidu Search Index,which reflects flu-related queries,strongly correlates with influenza trends,aiding in regional activity assessment and outbreak tracking[2].
基金Supported by the Natural Science Foundation of Guangxi Province(Grant Nos.2023GXNSFAA026067,2024GXN SFAA010521)the National Natural Science Foundation of China(Nos.12361079,12201149,12261026).
文摘Convex feasibility problems are widely used in image reconstruction,sparse signal recovery,and other areas.This paper is devoted to considering a class of convex feasibility problem arising from sparse signal recovery.We rst derive the projection formulas for a vector onto the feasible sets.The centralized circumcentered-reection method is designed to solve the convex feasibility problem.Some numerical experiments demonstrate the feasibility and e ectiveness of the proposed algorithm,showing superior performance compared to conventional alternating projection methods.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
文摘为揭示近断层地震动作用下岩质边坡的动态响应规律与灾变机制,提出了一种间接边界元法(indirect boundary element method,简称IBEM)与离散元法(discrete element method,简称DEM)耦合的时域分析体系,建立了考虑岩土体非连续变形特征的近断层-边坡系统非线性动力响应模拟方法。首先基于IBEM构建半无限域千米级近断层地震波场高精度数值模型;其次,结合格林函数理论与IBEM求解波场,推导DEM计算域边界等效地震荷载的显式表达,进而实现IBEM-DEM耦合系统的跨尺度能量传递;最终通过DEM求解米级岩质边坡的非线性动力响应,实现了从千米级断层到米级边坡的多尺度非线性地震动模拟方法体系。数值模拟与动态监测结果表明:IBEM-DEM耦合算法可精准表征近场地震波传播的频散特性与能量衰减规律;近断层地震荷载作用下,软弱夹层首先发生渐进式剪切破坏,其强度劣化导致贯通性破裂面的形成,并引致滑体沿剪切面加速失稳,产生显著位移与速度响应,最终在坡脚形成典型碎屑堆积体;滑体表层速度显著高于底层,表层平均速度达到底层平均速度的3.6倍,其中滑体表层X向和Z向的速度分量峰值分别达到4.98 m/s和5.92 m/s,呈现出明显的趋表效应;滑体监测点从初始坡面位置到最终堆积体位置的X向和Z向最大位移分别可达41 m和35 m,时程表现出典型阶跃式增长特征,反映出滑体在动能与势能交替转换中的突跃式滑移行为。IBEM-DEM耦合方法构建了从岩体破裂到滑坡成灾的全过程演化序列,为近断层地震动诱发滑坡的动力灾变分析提供了创新性分析方法体系,并为复杂地质条件下滑坡机制的识别及地震灾害的防控提供了理论依据与技术支持。
基金supported by National Natural Science Foundation of China (Grant No. 50775035)New Doctor Teacher Foundation of Southeast University of China (Grant No. 9202000024)
文摘The accurate measurement of the fill level in the ball mill has not been resolved because of the interplay of many variable factors, which led the mill to be operated under the uneconomical condition and lost a lot of energy. At present, some methods, such as vibration method and acoustic method, have been applied for measuring the fill level by the researchers. Aiming at the problem of the traditional methods for measuring the fill level, that is, the feature variables of the fill level suffer the influences of the ball load and the water content of the coal, a novel method to measure the fill level is proposed and a possible relation between the fill level and the angular position of the maximum vibration point on the mill shell is investigated. The angular positions of the maximum vibration point on the mill shell for different fill level cases are calculated theoretically under two assumptions, respectively. Meanwhile the charge motions of the mill for different fill level cases are simulated with the discrete element method （DEM）. And the simulation results are verified by comparing the motion trajectories of steel balls and power draft of the mill. The simulated movement trajectories of the outmost layer steel balls in the mill are monitored and analyzed to obtain the angular positions of the maximum vibration point on the mill shell. Both the results of the theoretical calculation and the 3D DEM simulation show that the position of the maximum vibration point on the mill shell moves to a lower angular positions as the fill level decreasing, which provides a new idea for measuring the filllevel accurately.
基金Key Project of National Natural Science Foundation of China No.40930531 National Youth Science Foun-dation of China No.40901185 Specialized Research Fund for the Doctoral Program of Higher Education No.20093207120008
文摘Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.
基金Supported by the Major State Basic Research Development Program of China （2011CB201505）, the National Natural Science Foundation of China （50976025） and the Key Proj ect.of Science and Technology of Henan Province （12B610012）.
文摘Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal particle was developed, and both contact force and gravity force were considered in the models. The simulation results were validated by our experiment. Three algorithms for representing an ellipsoidal particle were compared in macro and micro aspects. The results show that there exists big difference in the microscopic parameters such as kinetic energy, rotational kinetic energy, deformation, contact force and collision number which leads to the difference of macroscopic parameters. The relative error in the discharge rate and tracer particle position is the largest between 3-tangent-element representation and experimental results. The flow pattern is similar for the 5-element and 3-intersection representations. The only difference is the discharge rate of 5-element representation is larger than the experimental value and that of the 3-intersection representation has the contrary result. Finally the 3-intersection- element reoresentation is chosen in the simulation due to less comouting time than that of the 5-element renresentation.
