This study proposes a method for calculating the probability distribution of structural responses at different intensities using the endurance time(ET)method.The results can be used to calculate the fragility curve of...This study proposes a method for calculating the probability distribution of structural responses at different intensities using the endurance time(ET)method.The results can be used to calculate the fragility curve of structural collapse.The ET method involves dynamic analysis of a structure under an intensifying record over time.While conventional ET methods can determine the median of the structural response,they lack the ability to calculate its dispersion.To address this limitation,the present study utilizes ET analysis and single-degree-of-freedom(SDOF)systems to develop a method that considers the record-to-record variability for calculating the probability distribution of structural response.The accuracy of this method is evaluated by comparing it with the incremental dynamic analysis(IDA)method using special moment frames.The results demonstrate that the proposed method achieves a reasonably accurate estimation of dispersion while significantly reducing the computational burden(by approximately 95%)compared to the IDA method.展开更多
There are problems such as incomplete edges and poor noise suppression when a single fixed morphological structuring element is used to detect the edges in remote sensing images. For this reason, a morphological edge ...There are problems such as incomplete edges and poor noise suppression when a single fixed morphological structuring element is used to detect the edges in remote sensing images. For this reason, a morphological edge detection method for remote sensing image based on variable structuring element is proposed. Firstly, the structuring elements with different scales and multiple directions are constructed according to the diversity of remote sensing imagery targets. In order to suppress the noise of the target background and highlight the edge of the image target in the remote sensing image by adaptive Top hat and Bottom hat transform, the corresponding adaptive morphological operations are constructed based on variable structuring elements; Secondly, adaptive morphological edge detection is used to obtain multiple images with different scales and directional edge features; Finally, the image edges are obtained by weighted summation of each direction edge, and then the least square is used to fit the edges for accurate location of the edge contour of the target. The experimental results show that the proposed method not only can detect the complete edge of remote sensing image, but also has high edge detection accuracy and superior anti-noise performance. Compared with classical edge detection and the morphological edge detection with a fixed single structuring element, the proposed method performs better in edge detection effect, and the accuracy of detection can reach 95 %展开更多
The robust stabilization problem for a family of nonlinear plants with mismatch uncertainties is addressed, and a solution is presented based on variable structure control theory and H∞ control theory. A kind of boun...The robust stabilization problem for a family of nonlinear plants with mismatch uncertainties is addressed, and a solution is presented based on variable structure control theory and H∞ control theory. A kind of boundary layer is built near the ideal switch surface which can eliminate chattering in the switch surface. The proposed control method with L2 gain can guarantee exponential stability of a system state with no parameter uncertainty and exter- nal disturbance, while it can guarantee state ultimate boundness if parameter uncertainty and external disturbance exist. In the proposed design method, stability of the closed-loop system is analyzed by adopting the Lyapurtov func- tion approach. Finally the numerical simulation results show that the proposed smooth variable structure controller has good pelformance without chattering in the switch surface.展开更多
The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables,such as applied load,working temperature,geometrical dimensions and material properties.In order to am...The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables,such as applied load,working temperature,geometrical dimensions and material properties.In order to ameliorate reliability analysis efficiency without loss of reliability,the distributed collaborative response surface method(DCRSM) was proposed,and its basic theories were established in this work.Considering the failure dependency among the failure modes,the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables.Then,the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion.Finally,the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method.Through the comparison of DCRSM,Monte Carlo method(MCM) and the traditional response surface method(RSM),the results show that the computational precision for DCRSM is more consistent with MCM than RSM,while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions.Thus,DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables,and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.展开更多
Global population aging trends are intensifying,presenting multifaceted economic and social challenges for countries worldwide.As the world’s largest developing country,China has entered a phase of extreme demographi...Global population aging trends are intensifying,presenting multifaceted economic and social challenges for countries worldwide.As the world’s largest developing country,China has entered a phase of extreme demographic aging,posing significant questions about its impact on the ongoing upgrading of industrial structures.How does this demographic shift influence the upgrading of industrial structures,and does technological innovation mitigate or exacerbate this impact?The empirical results indicate that population aging impedes upgrading the industrial structure,while technological innovation positively affects the relationship between the two.Moreover,using technological innovation as a threshold variable,the impact of population aging on industrial structure upgrading evolves in a“gradient”manner from“impediment”to“insignificant”to“promotion”as the technological innovation levels increase.These findings offer practical guidance for tailoring industrial policies to different stages of technological advancement.展开更多
The dynamic characteristic analysis model of antenna structures is built,in which the structural physical parameters and geometrical dimensions are all considered as unascertained variables.And a structure dynamic cha...The dynamic characteristic analysis model of antenna structures is built,in which the structural physical parameters and geometrical dimensions are all considered as unascertained variables.And a structure dynamic characteristic analysis method based on the unascertained factor method is given.The computational expression of structural characteristic is developed by the mathematics expression of unascertained factor and the principles of unascertained rational numbers arithmetic.An example is given,in which the possible values and confidence degrees of the unascertained structure characteristics are obtained.The calculated results show that the method is feasible and effective.展开更多
目的评估新疆地区“药品零差率”政策对心脑血管疾病患者住院费用结构及次均费用的影响,为完善公立医院补偿机制与控费政策提供依据。方法基于新疆某三甲综合公立医院2016年1月-2023年12月心脑血管疾病患者住院费用数据,本研究聚焦次均...目的评估新疆地区“药品零差率”政策对心脑血管疾病患者住院费用结构及次均费用的影响,为完善公立医院补偿机制与控费政策提供依据。方法基于新疆某三甲综合公立医院2016年1月-2023年12月心脑血管疾病患者住院费用数据,本研究聚焦次均住院费用、次均西药费用及费用构成等核心指标,采用间断时间序列分析(Interrupted time series analysis,ITSA)量化了政策带来的费用水平与趋势的即时与长期变化,并结合结构变动度模型揭示了各分项费用的结构变动贡献率。结果与政策实施前比较,实施后次均住院费用短期内显著下降(β_(2)=-12754.66,P<0.05),长期呈缓慢回升趋势(β_(1)+β_(3)=107.40,P<0.05);西药费用占比下降,次均西药费用控制未达显著(P≥0.05)。医院通过增加检查费、化验费等医疗服务性收入(累计贡献率43.87%)弥补药品收入损失,存在将成本从药品转向检查、化验等医疗服务项目的风险。结论“药品零差率”政策短期内降低住院费用,但需深化医疗、医保、医药领域的协同改革,强化疾病诊断相关分组(Diagnosis related groups,DRG)付费、耗材集采等协同措施,遏制隐性成本转移,巩固政策成效。展开更多
Bimsoils,consist of fine soil matrix and coarse rock aggregates,and are widespread as sedimentary soils.The bearing behavior of bimsoils are significantly affected by rock fraction.However,the mechanism governing the ...Bimsoils,consist of fine soil matrix and coarse rock aggregates,and are widespread as sedimentary soils.The bearing behavior of bimsoils are significantly affected by rock fraction.However,the mechanism governing the coarse fraction effect remains unclear.The traditional analysis methods are not effective in describing the rock fraction effect due to heterogeneous structure.To this end,91 simulations have been performed to investigate the bearing capacity of bimsoils(mainly of two-dimensional,2D)under shallow foundations using finite element method(FEM).It is found that the densified matrix bridge as well as the coarse aggregates forms a strong contact network which is responsible for the coarse fraction effect.A structure variable is introduced to quantify the reinforcing effect of rock aggregates.Then,a model incorporating the structural variable is proposed to evaluate the coarse fraction effect on the bearing capacity of bimsoils.Compared with the conventional method for pure soil matrix,only two additional parameters are required,and they can be readily calibrated by laboratory tests.The model is further validated by data available in literature,which can effectively estimate the bearing capacity of bimsoils under shallow foundations with a various of rock contents and rock characteristics.展开更多
The study derives the Hirota bilinear form for a variable-coefficient(2+1)-dimensional BKP equation and constructs N-soliton,M-lump,and mixed lumpsoliton solutions.By testing four representative time-dependent coeffic...The study derives the Hirota bilinear form for a variable-coefficient(2+1)-dimensional BKP equation and constructs N-soliton,M-lump,and mixed lumpsoliton solutions.By testing four representative time-dependent coefficient sets,the authors visualise howα(t),β(t)andδ(t)shape the spatial patterns of solitons and lumps.The work emphasises the richer structural diversity and evolution pathways that arise when coefficients vary with time.展开更多
In this article, Crank-Nicolson method is used to study the variable order fractional cable equation. The variable order fractional derivatives are described in the Riemann- Liouville and the Griinwald-Letnikov sense....In this article, Crank-Nicolson method is used to study the variable order fractional cable equation. The variable order fractional derivatives are described in the Riemann- Liouville and the Griinwald-Letnikov sense. The stability analysis of the proposed technique is discussed. Numerical results are provided and compared with exact solutions to show the accuracy of the proposed technique.展开更多
With an extended mapping approach and a linear variable separation method, new families of variable separation solutions （including solitary wave solutions, periodic wave solutions, and rational function solutions） ...With an extended mapping approach and a linear variable separation method, new families of variable separation solutions （including solitary wave solutions, periodic wave solutions, and rational function solutions） with arbitrary functions for （3＋1）-dimensionai Burgers system is derived. Based on the derived excitations, we obtain some novel localized coherent structures and study the interactions between solitons.展开更多
Natural soil variability is a well-known issue in geotechnical design,although not frequently managed in practice.When subsoil must be characterized in terms of mechanical properties for infrastructure design,random f...Natural soil variability is a well-known issue in geotechnical design,although not frequently managed in practice.When subsoil must be characterized in terms of mechanical properties for infrastructure design,random finite element method(RFEM)can be effectively adopted for shallow foundation design to gain a twofold purpose:(1)understanding how much the bearing capacity is affected by the spatial variability structure of soils,and(2)optimisation of the foundation dimension(i.e.width B).The present study focuses on calculating the bearing capacity of shallow foundations by RFEM in terms of undrained and drained conditions.The spatial variability structure of soil is characterized by the autocorrelation function and the scale of fluctuation(δ).The latter has been derived by geostatistical tools such as the ordinary Kriging(OK)approach based on 182 cone penetration tests(CPTs)performed in the alluvial plain in Bologna Province,Italy.Results show that the increase of the B/δratio not only reduces the bearing capacity uncertainty but also increases its mean value under drained conditions.Conversely,under the undrained condition,the autocorrelation function strongly affects the mean values of bearing capacity.Therefore,the authors advise caution when selecting the autocorrelation function model for describing the soil spatial variability structure and point out that undrained conditions are more affected by soil variability compared to the drained ones.展开更多
文摘This study proposes a method for calculating the probability distribution of structural responses at different intensities using the endurance time(ET)method.The results can be used to calculate the fragility curve of structural collapse.The ET method involves dynamic analysis of a structure under an intensifying record over time.While conventional ET methods can determine the median of the structural response,they lack the ability to calculate its dispersion.To address this limitation,the present study utilizes ET analysis and single-degree-of-freedom(SDOF)systems to develop a method that considers the record-to-record variability for calculating the probability distribution of structural response.The accuracy of this method is evaluated by comparing it with the incremental dynamic analysis(IDA)method using special moment frames.The results demonstrate that the proposed method achieves a reasonably accurate estimation of dispersion while significantly reducing the computational burden(by approximately 95%)compared to the IDA method.
基金National Natural Science Foundation of China(No.61761027)Postgraduate Education Reform Project of Lanzhou Jiaotong University(No.1600120101)
文摘There are problems such as incomplete edges and poor noise suppression when a single fixed morphological structuring element is used to detect the edges in remote sensing images. For this reason, a morphological edge detection method for remote sensing image based on variable structuring element is proposed. Firstly, the structuring elements with different scales and multiple directions are constructed according to the diversity of remote sensing imagery targets. In order to suppress the noise of the target background and highlight the edge of the image target in the remote sensing image by adaptive Top hat and Bottom hat transform, the corresponding adaptive morphological operations are constructed based on variable structuring elements; Secondly, adaptive morphological edge detection is used to obtain multiple images with different scales and directional edge features; Finally, the image edges are obtained by weighted summation of each direction edge, and then the least square is used to fit the edges for accurate location of the edge contour of the target. The experimental results show that the proposed method not only can detect the complete edge of remote sensing image, but also has high edge detection accuracy and superior anti-noise performance. Compared with classical edge detection and the morphological edge detection with a fixed single structuring element, the proposed method performs better in edge detection effect, and the accuracy of detection can reach 95 %
文摘The robust stabilization problem for a family of nonlinear plants with mismatch uncertainties is addressed, and a solution is presented based on variable structure control theory and H∞ control theory. A kind of boundary layer is built near the ideal switch surface which can eliminate chattering in the switch surface. The proposed control method with L2 gain can guarantee exponential stability of a system state with no parameter uncertainty and exter- nal disturbance, while it can guarantee state ultimate boundness if parameter uncertainty and external disturbance exist. In the proposed design method, stability of the closed-loop system is analyzed by adopting the Lyapurtov func- tion approach. Finally the numerical simulation results show that the proposed smooth variable structure controller has good pelformance without chattering in the switch surface.
基金Project(51335003)supported by the National Natural Science Foundation of ChinaProject(20111102110011)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables,such as applied load,working temperature,geometrical dimensions and material properties.In order to ameliorate reliability analysis efficiency without loss of reliability,the distributed collaborative response surface method(DCRSM) was proposed,and its basic theories were established in this work.Considering the failure dependency among the failure modes,the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables.Then,the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion.Finally,the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method.Through the comparison of DCRSM,Monte Carlo method(MCM) and the traditional response surface method(RSM),the results show that the computational precision for DCRSM is more consistent with MCM than RSM,while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions.Thus,DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables,and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.
基金supported by the Research Center for Aging Career and Industrial Development,Sichuan Key Research Base of Social Sciences[Grant No.XJLL2022009].
文摘Global population aging trends are intensifying,presenting multifaceted economic and social challenges for countries worldwide.As the world’s largest developing country,China has entered a phase of extreme demographic aging,posing significant questions about its impact on the ongoing upgrading of industrial structures.How does this demographic shift influence the upgrading of industrial structures,and does technological innovation mitigate or exacerbate this impact?The empirical results indicate that population aging impedes upgrading the industrial structure,while technological innovation positively affects the relationship between the two.Moreover,using technological innovation as a threshold variable,the impact of population aging on industrial structure upgrading evolves in a“gradient”manner from“impediment”to“insignificant”to“promotion”as the technological innovation levels increase.These findings offer practical guidance for tailoring industrial policies to different stages of technological advancement.
基金the National Defense Science and Technology Research Projects of China (51421060505DZ0155)the National Science Foundation of Shaanxi Province of China (2005A009)
文摘The dynamic characteristic analysis model of antenna structures is built,in which the structural physical parameters and geometrical dimensions are all considered as unascertained variables.And a structure dynamic characteristic analysis method based on the unascertained factor method is given.The computational expression of structural characteristic is developed by the mathematics expression of unascertained factor and the principles of unascertained rational numbers arithmetic.An example is given,in which the possible values and confidence degrees of the unascertained structure characteristics are obtained.The calculated results show that the method is feasible and effective.
文摘目的评估新疆地区“药品零差率”政策对心脑血管疾病患者住院费用结构及次均费用的影响,为完善公立医院补偿机制与控费政策提供依据。方法基于新疆某三甲综合公立医院2016年1月-2023年12月心脑血管疾病患者住院费用数据,本研究聚焦次均住院费用、次均西药费用及费用构成等核心指标,采用间断时间序列分析(Interrupted time series analysis,ITSA)量化了政策带来的费用水平与趋势的即时与长期变化,并结合结构变动度模型揭示了各分项费用的结构变动贡献率。结果与政策实施前比较,实施后次均住院费用短期内显著下降(β_(2)=-12754.66,P<0.05),长期呈缓慢回升趋势(β_(1)+β_(3)=107.40,P<0.05);西药费用占比下降,次均西药费用控制未达显著(P≥0.05)。医院通过增加检查费、化验费等医疗服务性收入(累计贡献率43.87%)弥补药品收入损失,存在将成本从药品转向检查、化验等医疗服务项目的风险。结论“药品零差率”政策短期内降低住院费用,但需深化医疗、医保、医药领域的协同改革,强化疾病诊断相关分组(Diagnosis related groups,DRG)付费、耗材集采等协同措施,遏制隐性成本转移,巩固政策成效。
基金partially supported by the National Natural Science Foundation of China(Grant Nos.52278346,52178328,42377190).
文摘Bimsoils,consist of fine soil matrix and coarse rock aggregates,and are widespread as sedimentary soils.The bearing behavior of bimsoils are significantly affected by rock fraction.However,the mechanism governing the coarse fraction effect remains unclear.The traditional analysis methods are not effective in describing the rock fraction effect due to heterogeneous structure.To this end,91 simulations have been performed to investigate the bearing capacity of bimsoils(mainly of two-dimensional,2D)under shallow foundations using finite element method(FEM).It is found that the densified matrix bridge as well as the coarse aggregates forms a strong contact network which is responsible for the coarse fraction effect.A structure variable is introduced to quantify the reinforcing effect of rock aggregates.Then,a model incorporating the structural variable is proposed to evaluate the coarse fraction effect on the bearing capacity of bimsoils.Compared with the conventional method for pure soil matrix,only two additional parameters are required,and they can be readily calibrated by laboratory tests.The model is further validated by data available in literature,which can effectively estimate the bearing capacity of bimsoils under shallow foundations with a various of rock contents and rock characteristics.
基金supported by the National Natural Science Foundation of China(Grant No.12461047)the Scientific Research Project of the Hunan Education Department(Grant No.24B0478).
文摘The study derives the Hirota bilinear form for a variable-coefficient(2+1)-dimensional BKP equation and constructs N-soliton,M-lump,and mixed lumpsoliton solutions.By testing four representative time-dependent coefficient sets,the authors visualise howα(t),β(t)andδ(t)shape the spatial patterns of solitons and lumps.The work emphasises the richer structural diversity and evolution pathways that arise when coefficients vary with time.
文摘In this article, Crank-Nicolson method is used to study the variable order fractional cable equation. The variable order fractional derivatives are described in the Riemann- Liouville and the Griinwald-Letnikov sense. The stability analysis of the proposed technique is discussed. Numerical results are provided and compared with exact solutions to show the accuracy of the proposed technique.
基金The project supported by the Natural Science Foundation of Zhejiang Province under Grant Nos.Y606128 and Y604106the Natural Science Foundation of Zhejiang Lishui University under Grant Nos.FC06001 and QN06009
文摘With an extended mapping approach and a linear variable separation method, new families of variable separation solutions （including solitary wave solutions, periodic wave solutions, and rational function solutions） with arbitrary functions for （3＋1）-dimensionai Burgers system is derived. Based on the derived excitations, we obtain some novel localized coherent structures and study the interactions between solitons.
文摘Natural soil variability is a well-known issue in geotechnical design,although not frequently managed in practice.When subsoil must be characterized in terms of mechanical properties for infrastructure design,random finite element method(RFEM)can be effectively adopted for shallow foundation design to gain a twofold purpose:(1)understanding how much the bearing capacity is affected by the spatial variability structure of soils,and(2)optimisation of the foundation dimension(i.e.width B).The present study focuses on calculating the bearing capacity of shallow foundations by RFEM in terms of undrained and drained conditions.The spatial variability structure of soil is characterized by the autocorrelation function and the scale of fluctuation(δ).The latter has been derived by geostatistical tools such as the ordinary Kriging(OK)approach based on 182 cone penetration tests(CPTs)performed in the alluvial plain in Bologna Province,Italy.Results show that the increase of the B/δratio not only reduces the bearing capacity uncertainty but also increases its mean value under drained conditions.Conversely,under the undrained condition,the autocorrelation function strongly affects the mean values of bearing capacity.Therefore,the authors advise caution when selecting the autocorrelation function model for describing the soil spatial variability structure and point out that undrained conditions are more affected by soil variability compared to the drained ones.
