In order to overcome the drawbacks of conventional artificial potential fields (APF) based methods for the motion planning problems of mobile robots in dynamic uncertain environments, an artificial coordinating fields...In order to overcome the drawbacks of conventional artificial potential fields (APF) based methods for the motion planning problems of mobile robots in dynamic uncertain environments, an artificial coordinating fields (ACF) based method has been proposed recently. This paper deals with the reachability problem of the ACF, that is, how to design and choose the parameters of the ACF and how the environment should be such that the robot can reach its goal without being trapped in local minima. Some sufficient conditions for these purposes are developed theoretically. Theoretical analyses show that, the ACF can effectively remove local minima in dynamic uncertain environments with V-shape or U-shape obstacles, and guide the mobile robot to reach its goal with some necessary environment constraints and based on the methods provided in this paper to properly choose the parameters of the ACF. Comparisons between the ACF and APF, and simulations are provided to illustrate the advantages of the ACF.展开更多
This paper deals with extensions of higher-order optimality conditions for scalar optimization to multiobjective optimization.A type of directional derivatives for a multiobjective function is proposed,and with this n...This paper deals with extensions of higher-order optimality conditions for scalar optimization to multiobjective optimization.A type of directional derivatives for a multiobjective function is proposed,and with this notion characterizations of strict local minima of order k for a multiobjective optimization problem with a nonempty set constraint are established,generalizing the corresponding scalar case obtained by Studniarski[3].Also necessary not sufficient and sufficient not necessary optimality conditions for this minima are derived based on our directional derivatives,which are generalizations of some existing scalar results and equivalent to some existing multiobjective ones.Many examples are given to illustrate them there.展开更多
This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual fo...This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual force （VF） is constructed and the corresponding optimal solving method under the given indicators is presented. Specifically,a fixed step method is developed to reduce computational cost and the reachable condition of path planning is proved. The Bayesian belief network and fuzzy logic reasoning theories are applied to setting the path planning parameters adaptively,which can reflect the battlefield situation dy-namically and precisely. A new way of combining threats is proposed to solve the local minima problem completely. Simulation results prove the feasibility and usefulness of using FVF for UAV path planning. Performance comparisons between the FVF method and the A＊ search algorithm demonstrate that the proposed approach is fast enough to meet the real-time requirements of the online path planning problems.展开更多
Common optimization methods for enhanced distillation include sequential iteration methods and metaheuristic algorithms,which typically face tedious computation and are easily trapped into local minimum.Therefore,it i...Common optimization methods for enhanced distillation include sequential iteration methods and metaheuristic algorithms,which typically face tedious computation and are easily trapped into local minimum.Therefore,it is essential to develop a strategy that enables simultaneous evaluation of multiple solutions.In this paper,a global optimization framework integrating MATLAB and Aspen Plus for liquid-only extractive dividing wall column(LEDWC)and conventional extractive distillation(CED)systems is proposed to enhance both computational efficiencyand search robustness.All possible combinations of key variables,including distillate and entrainer flowrates,feed stage,and total stage numbers,etc.-are considered systematically.They are arranged in full permutation within a sufficiently wide range.The permutation is then divided into multiple matrices by MATLAB.They are sequentially input into sensitivity analysis module in Aspen Plus through communication with MATLAB.Each group of integrated variables which satisfiesthe given constraints is used for the total annual cost(TAC)calculation.The mixture of ethanol(EtOH)and water,which can form a minimum boiling azeotrope(89.6%(mol)EtOH)at 100 kPa,is taken as a study system.Five different feed mixtures are taken for comprehensive analysis.The TAC profilesas a function of the total number of stages for the left column(NCL)in the LEDWC clearly indicate that the proposed strategy successfully identifiedmultiple local minima,demonstrating its capability to detect and escape suboptimal regions in highly nonlinear systems.The existence of local minima can be attributed to the coupling interaction between structural and process variables,as well as the influenceof flowcharacteristics within the column.This work indicates that as NCL increases,there is a competitive effect between the decrease in refluxratio for the left column(RRCL)and the increase in reboiler temperature,leading to fluctuationsin energy consumption;while changes in the distillation flowrate for the left column cause nonlinear changes in RRCL and the liquid flowrate between the left and right columns,further promoting the emergence of multiple local minima during the TAC optimization process.Additionally,analysis of the flowcharacteristics within the column revealed that the back-mixing phenomenon commonly observed in CED is absent in LEDWC,suggesting that back-mixing may be an important factor contributing to the more frequent occurrence of local optima.展开更多
基金This paper was partly supported by the National Natural Science Foundation (No.60131160741,60334010) of China.
文摘In order to overcome the drawbacks of conventional artificial potential fields (APF) based methods for the motion planning problems of mobile robots in dynamic uncertain environments, an artificial coordinating fields (ACF) based method has been proposed recently. This paper deals with the reachability problem of the ACF, that is, how to design and choose the parameters of the ACF and how the environment should be such that the robot can reach its goal without being trapped in local minima. Some sufficient conditions for these purposes are developed theoretically. Theoretical analyses show that, the ACF can effectively remove local minima in dynamic uncertain environments with V-shape or U-shape obstacles, and guide the mobile robot to reach its goal with some necessary environment constraints and based on the methods provided in this paper to properly choose the parameters of the ACF. Comparisons between the ACF and APF, and simulations are provided to illustrate the advantages of the ACF.
文摘This paper deals with extensions of higher-order optimality conditions for scalar optimization to multiobjective optimization.A type of directional derivatives for a multiobjective function is proposed,and with this notion characterizations of strict local minima of order k for a multiobjective optimization problem with a nonempty set constraint are established,generalizing the corresponding scalar case obtained by Studniarski[3].Also necessary not sufficient and sufficient not necessary optimality conditions for this minima are derived based on our directional derivatives,which are generalizations of some existing scalar results and equivalent to some existing multiobjective ones.Many examples are given to illustrate them there.
基金National Natural Science Foundation of China (60975073)Aeronautical Science Foundation of China (2008ZC13011)+1 种基金Research Foundation for Doctoral Program of Higher Education of China (20091102110006)Fundamental Research Funds for the Central Universities
文摘This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual force （VF） is constructed and the corresponding optimal solving method under the given indicators is presented. Specifically,a fixed step method is developed to reduce computational cost and the reachable condition of path planning is proved. The Bayesian belief network and fuzzy logic reasoning theories are applied to setting the path planning parameters adaptively,which can reflect the battlefield situation dy-namically and precisely. A new way of combining threats is proposed to solve the local minima problem completely. Simulation results prove the feasibility and usefulness of using FVF for UAV path planning. Performance comparisons between the FVF method and the A＊ search algorithm demonstrate that the proposed approach is fast enough to meet the real-time requirements of the online path planning problems.
文摘Common optimization methods for enhanced distillation include sequential iteration methods and metaheuristic algorithms,which typically face tedious computation and are easily trapped into local minimum.Therefore,it is essential to develop a strategy that enables simultaneous evaluation of multiple solutions.In this paper,a global optimization framework integrating MATLAB and Aspen Plus for liquid-only extractive dividing wall column(LEDWC)and conventional extractive distillation(CED)systems is proposed to enhance both computational efficiencyand search robustness.All possible combinations of key variables,including distillate and entrainer flowrates,feed stage,and total stage numbers,etc.-are considered systematically.They are arranged in full permutation within a sufficiently wide range.The permutation is then divided into multiple matrices by MATLAB.They are sequentially input into sensitivity analysis module in Aspen Plus through communication with MATLAB.Each group of integrated variables which satisfiesthe given constraints is used for the total annual cost(TAC)calculation.The mixture of ethanol(EtOH)and water,which can form a minimum boiling azeotrope(89.6%(mol)EtOH)at 100 kPa,is taken as a study system.Five different feed mixtures are taken for comprehensive analysis.The TAC profilesas a function of the total number of stages for the left column(NCL)in the LEDWC clearly indicate that the proposed strategy successfully identifiedmultiple local minima,demonstrating its capability to detect and escape suboptimal regions in highly nonlinear systems.The existence of local minima can be attributed to the coupling interaction between structural and process variables,as well as the influenceof flowcharacteristics within the column.This work indicates that as NCL increases,there is a competitive effect between the decrease in refluxratio for the left column(RRCL)and the increase in reboiler temperature,leading to fluctuationsin energy consumption;while changes in the distillation flowrate for the left column cause nonlinear changes in RRCL and the liquid flowrate between the left and right columns,further promoting the emergence of multiple local minima during the TAC optimization process.Additionally,analysis of the flowcharacteristics within the column revealed that the back-mixing phenomenon commonly observed in CED is absent in LEDWC,suggesting that back-mixing may be an important factor contributing to the more frequent occurrence of local optima.
