Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is...Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.展开更多
目的分析影响ICU脓毒症患者预后的危险因素及血镁水平联合急性生理与慢性健康Ⅱ(acute physiology and chronic health evaluationⅡ,APACHE-Ⅱ)评分对ICU脓毒症患者预后的预测价值。方法对2020年1月—2022年1月期间收治的185例ICU脓毒...目的分析影响ICU脓毒症患者预后的危险因素及血镁水平联合急性生理与慢性健康Ⅱ(acute physiology and chronic health evaluationⅡ,APACHE-Ⅱ)评分对ICU脓毒症患者预后的预测价值。方法对2020年1月—2022年1月期间收治的185例ICU脓毒症患者展开回顾性研究,依据患者28 d生存情况将其分为死亡组(n=94)和存活组(n=91),单因素和logistic多因素分析脓毒症患者28 d死亡的危险因素。Pearson分析血镁水平、APACHE-Ⅱ评分与各项危险因素的相关性,受试者工作特征曲线(receiver operating characteristic,ROC)分析血镁联合APACHE-Ⅱ评分对ICU脓毒症患者预后的预测价值。结果APACHE-Ⅱ评分、序贯器官衰竭评分(sequential organ failure assessment,SOFA)、降钙素原(procalcitonin,PCT)、低镁血症、血小板计数为ICU脓毒症患者28d死亡的危险因素(P<0.05)。APACHE-Ⅱ评分与SOFA评分、PCT水平、低镁血症均呈现正相关(P<0.05),与血小板计数呈现负相关(P<0.05)。低镁血症与APACHE-Ⅱ评分、SOFA评分、PCT水平均呈现正相关(P<0.05),与血小板计数呈现负相关(P<0.05)。低镁血症(AUC=0.697)、APACHE-Ⅱ评分(AUC=0.745)对ICU脓毒症患者预后均有较好的预测价值,且二者联合(AUC=0.866)预测效果更佳。结论低镁血症联合APACHE-Ⅱ评分ICU脓毒症患者28 d死亡有较好的预测价值,临床中可将血镁水平和APACHE-Ⅱ评分作为判断预后的指标。展开更多
Modern automated generation control(AGC)is increasingly complex,requiring precise frequency control for stability and operational accuracy.Traditional PID controller optimisation methods often struggle to handle nonli...Modern automated generation control(AGC)is increasingly complex,requiring precise frequency control for stability and operational accuracy.Traditional PID controller optimisation methods often struggle to handle nonlinearities and meet robustness requirements across diverse operational scenarios.This paper introduces an enhanced strategy using a multi-objective optimisation framework and a modified non-dominated sorting genetic algorithm Ⅱ(SNSGA).The proposed model optimises the PID controller by minimising key performance metrics:integration time squared error(ITSE),integration time absolute error(ITAE),and rate of change of deviation(J).This approach balances convergence rate,overshoot,and oscillation dynamics effectively.A fuzzy-based method is employed to select the most suitable solution from the Pareto set.The comparative analysis demonstrates that the SNSGA-based approach offers superior tuning capabilities over traditional NSGA-Ⅱ and other advanced control methods.In a two-area thermal power system without reheat,the SNSGA significantly reduces settling times for frequency deviations:2.94s for Δf_(1) and 4.98s for Δf_(2),marking improvements of 31.6%and 13.4%over NSGA-Ⅱ,respectively.展开更多
横波可控震源振动器平板作为页岩气勘探中的关键部件,其疲劳寿命直接影响可控震源的使用寿命和勘探精度。然而,传统的振动器平板疲劳寿命优化方法未考虑平板与平板齿间焊接残余应力的影响,导致平板结构在抗疲劳优化设计方面效果不佳。为...横波可控震源振动器平板作为页岩气勘探中的关键部件,其疲劳寿命直接影响可控震源的使用寿命和勘探精度。然而,传统的振动器平板疲劳寿命优化方法未考虑平板与平板齿间焊接残余应力的影响,导致平板结构在抗疲劳优化设计方面效果不佳。为此,使用局部灵敏度法对平板疲劳寿命进行敏感性分析,确定了焊接残余应力为影响疲劳寿命的关键因素。随后,建立了平板的各向最大焊接残余应力与焊接速度和焊接层间温度之间的数学模型,并以各向最大焊接残余应力为约束,以疲劳寿命为优化目标,建立相应的优化模型。最后,利用NSGA-Ⅱ(nondominated sorting genetic algorithm-Ⅱ,非支配排序遗传算法-Ⅱ)获取Pareto解集,并结合熵权法和TOPSIS(technique for order preference by similarity to ideal solution,逼近理想解排序)法确定最佳优化方案:焊接速度为10.23 mm/s,焊接层间温度为105℃。结果表明,优化后平板的疲劳寿命为10.23年,相比优化前提高了17.72%。研究结果可为横波可控震源振动器平板的疲劳寿命优化提供科学有效的理论方法和工程指导。展开更多
基金National Natural Science Foundation of China under Grant No.52278490。
文摘Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.
文摘目的分析影响ICU脓毒症患者预后的危险因素及血镁水平联合急性生理与慢性健康Ⅱ(acute physiology and chronic health evaluationⅡ,APACHE-Ⅱ)评分对ICU脓毒症患者预后的预测价值。方法对2020年1月—2022年1月期间收治的185例ICU脓毒症患者展开回顾性研究,依据患者28 d生存情况将其分为死亡组(n=94)和存活组(n=91),单因素和logistic多因素分析脓毒症患者28 d死亡的危险因素。Pearson分析血镁水平、APACHE-Ⅱ评分与各项危险因素的相关性,受试者工作特征曲线(receiver operating characteristic,ROC)分析血镁联合APACHE-Ⅱ评分对ICU脓毒症患者预后的预测价值。结果APACHE-Ⅱ评分、序贯器官衰竭评分(sequential organ failure assessment,SOFA)、降钙素原(procalcitonin,PCT)、低镁血症、血小板计数为ICU脓毒症患者28d死亡的危险因素(P<0.05)。APACHE-Ⅱ评分与SOFA评分、PCT水平、低镁血症均呈现正相关(P<0.05),与血小板计数呈现负相关(P<0.05)。低镁血症与APACHE-Ⅱ评分、SOFA评分、PCT水平均呈现正相关(P<0.05),与血小板计数呈现负相关(P<0.05)。低镁血症(AUC=0.697)、APACHE-Ⅱ评分(AUC=0.745)对ICU脓毒症患者预后均有较好的预测价值,且二者联合(AUC=0.866)预测效果更佳。结论低镁血症联合APACHE-Ⅱ评分ICU脓毒症患者28 d死亡有较好的预测价值,临床中可将血镁水平和APACHE-Ⅱ评分作为判断预后的指标。
基金supported in part by the Science and Technology Innovation Program of Hunan Province under Grant 2022RC4028in part by the National Natural Science Foundation of China under Grant 62473204+3 种基金in part by the Chunhui Program Collaborative Scientific Research Project under Grant 202202004in part by the Natural Science Foundation of Nanjing University of Posts and Telecommunications under Grants NY221082,NY222144,and NY223075in part by the Huali Program for Excellent Talents in Nanjing University of Posts and Telecommunicationsin part by the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant KYCX24_1215.
文摘Modern automated generation control(AGC)is increasingly complex,requiring precise frequency control for stability and operational accuracy.Traditional PID controller optimisation methods often struggle to handle nonlinearities and meet robustness requirements across diverse operational scenarios.This paper introduces an enhanced strategy using a multi-objective optimisation framework and a modified non-dominated sorting genetic algorithm Ⅱ(SNSGA).The proposed model optimises the PID controller by minimising key performance metrics:integration time squared error(ITSE),integration time absolute error(ITAE),and rate of change of deviation(J).This approach balances convergence rate,overshoot,and oscillation dynamics effectively.A fuzzy-based method is employed to select the most suitable solution from the Pareto set.The comparative analysis demonstrates that the SNSGA-based approach offers superior tuning capabilities over traditional NSGA-Ⅱ and other advanced control methods.In a two-area thermal power system without reheat,the SNSGA significantly reduces settling times for frequency deviations:2.94s for Δf_(1) and 4.98s for Δf_(2),marking improvements of 31.6%and 13.4%over NSGA-Ⅱ,respectively.
文摘横波可控震源振动器平板作为页岩气勘探中的关键部件,其疲劳寿命直接影响可控震源的使用寿命和勘探精度。然而,传统的振动器平板疲劳寿命优化方法未考虑平板与平板齿间焊接残余应力的影响,导致平板结构在抗疲劳优化设计方面效果不佳。为此,使用局部灵敏度法对平板疲劳寿命进行敏感性分析,确定了焊接残余应力为影响疲劳寿命的关键因素。随后,建立了平板的各向最大焊接残余应力与焊接速度和焊接层间温度之间的数学模型,并以各向最大焊接残余应力为约束,以疲劳寿命为优化目标,建立相应的优化模型。最后,利用NSGA-Ⅱ(nondominated sorting genetic algorithm-Ⅱ,非支配排序遗传算法-Ⅱ)获取Pareto解集,并结合熵权法和TOPSIS(technique for order preference by similarity to ideal solution,逼近理想解排序)法确定最佳优化方案:焊接速度为10.23 mm/s,焊接层间温度为105℃。结果表明,优化后平板的疲劳寿命为10.23年,相比优化前提高了17.72%。研究结果可为横波可控震源振动器平板的疲劳寿命优化提供科学有效的理论方法和工程指导。
