Fiber reinforced polymers (FRPs), unlike steel, are corrosion-resistant and therefore are of interest;however, their use is hindered because their brittle shear is formulated in most specifications using limited data ...Fiber reinforced polymers (FRPs), unlike steel, are corrosion-resistant and therefore are of interest;however, their use is hindered because their brittle shear is formulated in most specifications using limited data available at the time. We aimed to predict the shear strength of concrete beams reinforced with FRP bars and without stirrups by compiling a relatively large database of 198 previously published test results (available in appendix). To model shear strength, an artificial neural network was trained by an ensemble of Levenberg-Marquardt and imperialist competitive algorithms. The results suggested superior accuracy of model compared to equations available in specifications and literature.展开更多
Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective fun...Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm(ICA). The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.展开更多
One important application of independent component analysis （ICA） is in image processing. A two dimensional （2-D） composite ICA algorithm framework for 2-D image independent component analysis （2-D ICA） is propo...One important application of independent component analysis （ICA） is in image processing. A two dimensional （2-D） composite ICA algorithm framework for 2-D image independent component analysis （2-D ICA） is proposed. The 2-D nature of the algorithm provides it an advantage of circumventing the roundabout transforming procedures between two dimensional （2-D） image deta and one-dimensional （l-D） signal. Moreover the combination of the Newton （fixed-point algorithm） and natural gradient algorithms in this composite algorithm increases its efficiency and robustness. The convincing results of a successful example in functional magnetic resonance imaging （fMRI） show the potential application of composite 2-D ICA in the brain activity detection.展开更多
The optimal setting of directional overcurrent relays(DOCRs)ensures the fault detection and clearing in the minimum possible operation time.Directional protective relaying is carried out to coordinate relay settings i...The optimal setting of directional overcurrent relays(DOCRs)ensures the fault detection and clearing in the minimum possible operation time.Directional protective relaying is carried out to coordinate relay settings in a meshed network in the presence of distributed generation.The main goal of DOCR coordination is to find the optimal time dial setting(TDS)and pickup multiplier setting(PMS)to reach the minimum total operation time of all primary relays in the presence of coordination constraints.Due to the complexity of mixed integer non-linear programming(MINLP)problem,imperialistic competition algorithm(ICA)as a powerful evolutionary algorithm is used to solve the coordination problem of DOCRs.The proposed DOCR coordination formulation is implemented in three different test cases.The results are compared with the standard branch-and-bound algorithm and other meta-heuristic optimization algorithms,which demonstrates the effectiveness of the proposed algorithm.展开更多
The rising demand for high-density power storage systems such as hydrogen,combined with renewable power production systems,has led to the design of optimal power production and storage systems.In this study,a wind and...The rising demand for high-density power storage systems such as hydrogen,combined with renewable power production systems,has led to the design of optimal power production and storage systems.In this study,a wind and photovoltaic(PV)hybrid electrolyzer system,which maximizes the hydrogen production for a diurnal operation of the system,is designed and simulated.The operation of the system is optimized using imperialist competitive algorithm(ICA).The objective of this optimization is to combine the PV array and wind turbine(WT)in a way that,for minimized average excess power generation,maximum hydrogen would be produced.Actual meteorological data of Miami is used for simulations.A framework of the advanced alkaline electrolyzer with the detailed electrochemical model is used.This optimal system comprises a PV module with a power of 7.9 kW and a WT module with a power of 11 kW.The rate of hydrogen production is 0.0192 mol/s;an average Faraday efficiency of 86.9 percent.The electrolyzer works with 53.7 percent of its nominal power.The availability of the wind for longer periods of time reflects the greater contribution of WT in comparison with PV towards the overall throughput of the system.展开更多
Despite the success of the imperialist competitive algorithm(ICA)in solving optimization problems,it still suffers from frequently falling into local minima and low convergence speed.In this paper,a fuzzy version of t...Despite the success of the imperialist competitive algorithm(ICA)in solving optimization problems,it still suffers from frequently falling into local minima and low convergence speed.In this paper,a fuzzy version of this algorithm is proposed to address these issues.In contrast to the standard version of ICA,in the proposed algorithm,powerful countries are chosen as imperialists in each step;according to a fuzzy membership function,other countries become colonies of all the empires.In absorption policy,based on the fuzzy membership function,colonies move toward the resulting vector of all imperialists.In this algorithm,no empire will be eliminated;instead,during the execution of the algorithm,empires move toward one point.Other steps of the algorithm are similar to the standard ICA.In experiments,the proposed algorithm has been used to solve the real world optimization problems presented for IEEE-CEC 2011 evolutionary algorithm competition.Results of experiments confirm the performance of the algorithm.展开更多
文摘Fiber reinforced polymers (FRPs), unlike steel, are corrosion-resistant and therefore are of interest;however, their use is hindered because their brittle shear is formulated in most specifications using limited data available at the time. We aimed to predict the shear strength of concrete beams reinforced with FRP bars and without stirrups by compiling a relatively large database of 198 previously published test results (available in appendix). To model shear strength, an artificial neural network was trained by an ensemble of Levenberg-Marquardt and imperialist competitive algorithms. The results suggested superior accuracy of model compared to equations available in specifications and literature.
文摘Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm(ICA). The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.
基金Supported by the 973 Project (No.2003CB716106), NSFC (No.90208003, 30200059), TRAPOYT, Doctor Training Fund of MOE, PRC, Key Research Project of Science and Technology of MOE, Fok Ying Tong Education Foundation (No.91041)
文摘One important application of independent component analysis （ICA） is in image processing. A two dimensional （2-D） composite ICA algorithm framework for 2-D image independent component analysis （2-D ICA） is proposed. The 2-D nature of the algorithm provides it an advantage of circumventing the roundabout transforming procedures between two dimensional （2-D） image deta and one-dimensional （l-D） signal. Moreover the combination of the Newton （fixed-point algorithm） and natural gradient algorithms in this composite algorithm increases its efficiency and robustness. The convincing results of a successful example in functional magnetic resonance imaging （fMRI） show the potential application of composite 2-D ICA in the brain activity detection.
文摘The optimal setting of directional overcurrent relays(DOCRs)ensures the fault detection and clearing in the minimum possible operation time.Directional protective relaying is carried out to coordinate relay settings in a meshed network in the presence of distributed generation.The main goal of DOCR coordination is to find the optimal time dial setting(TDS)and pickup multiplier setting(PMS)to reach the minimum total operation time of all primary relays in the presence of coordination constraints.Due to the complexity of mixed integer non-linear programming(MINLP)problem,imperialistic competition algorithm(ICA)as a powerful evolutionary algorithm is used to solve the coordination problem of DOCRs.The proposed DOCR coordination formulation is implemented in three different test cases.The results are compared with the standard branch-and-bound algorithm and other meta-heuristic optimization algorithms,which demonstrates the effectiveness of the proposed algorithm.
基金supported by the National Science Foundation (No.1553494)
文摘The rising demand for high-density power storage systems such as hydrogen,combined with renewable power production systems,has led to the design of optimal power production and storage systems.In this study,a wind and photovoltaic(PV)hybrid electrolyzer system,which maximizes the hydrogen production for a diurnal operation of the system,is designed and simulated.The operation of the system is optimized using imperialist competitive algorithm(ICA).The objective of this optimization is to combine the PV array and wind turbine(WT)in a way that,for minimized average excess power generation,maximum hydrogen would be produced.Actual meteorological data of Miami is used for simulations.A framework of the advanced alkaline electrolyzer with the detailed electrochemical model is used.This optimal system comprises a PV module with a power of 7.9 kW and a WT module with a power of 11 kW.The rate of hydrogen production is 0.0192 mol/s;an average Faraday efficiency of 86.9 percent.The electrolyzer works with 53.7 percent of its nominal power.The availability of the wind for longer periods of time reflects the greater contribution of WT in comparison with PV towards the overall throughput of the system.
文摘Despite the success of the imperialist competitive algorithm(ICA)in solving optimization problems,it still suffers from frequently falling into local minima and low convergence speed.In this paper,a fuzzy version of this algorithm is proposed to address these issues.In contrast to the standard version of ICA,in the proposed algorithm,powerful countries are chosen as imperialists in each step;according to a fuzzy membership function,other countries become colonies of all the empires.In absorption policy,based on the fuzzy membership function,colonies move toward the resulting vector of all imperialists.In this algorithm,no empire will be eliminated;instead,during the execution of the algorithm,empires move toward one point.Other steps of the algorithm are similar to the standard ICA.In experiments,the proposed algorithm has been used to solve the real world optimization problems presented for IEEE-CEC 2011 evolutionary algorithm competition.Results of experiments confirm the performance of the algorithm.
