A mass-spring-damper linear oscillator with a limiting stop barrier is presented. Modeling non-smooth processes in mechanical engineering is a complex problem. It is especially for the systems with more than a single ...A mass-spring-damper linear oscillator with a limiting stop barrier is presented. Modeling non-smooth processes in mechanical engineering is a complex problem. It is especially for the systems with more than a single degree of freedom. But recent studies in dynamical systems have been applied to single degree of freedom systems. The vibrating system, consisting of an oscillator with amplitude of motion limited by a barrier, is known as a vibro-impact system. The amount of force and kinetic energy transferred to a barrier has an important application in designing of engineering systems that undergo the vibro-impact phenomenon. The results show the effect of changing restitution coefficient of a barrier on the amount of force and energy absorbed.展开更多
A wavelet-based power management system is proposed in this paper with a combination of the battery and ultracapacitor(UC)hybrid energy storage system(HESS).The wavelet filter serves as a frequency-based filter for di...A wavelet-based power management system is proposed in this paper with a combination of the battery and ultracapacitor(UC)hybrid energy storage system(HESS).The wavelet filter serves as a frequency-based filter for distributing the power between the battery and UC.In order to determine the optimal level of wavelet decomposition as well as the optimal activation power of the wavelet controller,an optimization procedure is established.The proposed frequency-based power management system moderates the usage of battery current,consequently improving its lifetime.Compared with the conventional threshold-based power management systems,the proposed system has the advantage of enhanced battery and UC power management.A LiFePO4 battery is considered and its life loss is modeled.As a case study,an electric motorcycle is evaluated in the federal test procedure(FTP)driving cycle.Compared with a conventional energy storage system(ESS)and a state of available power(SoP)management systems,the results show an improvement for the battery lifetime by 115%and 3%,respectively.The number of battery replacements is increased,and the energy recovery is improved.The 10-year overall costs of the proposed HESS strategy using wavelet are1500 dollars lower,compared with the ESS.展开更多
This paper presents new hybrid methods for the identification of optimal topologies by combining the teaching-learning based optimization(TLBO)and the method of moving asymptotes(MMA).The topology optimization problem...This paper presents new hybrid methods for the identification of optimal topologies by combining the teaching-learning based optimization(TLBO)and the method of moving asymptotes(MMA).The topology optimization problem is parameterizing with a low dimensional explicit method called moving morphable components(MMC),to make the use of evolutionary algorithms more efficient.Gradient-based solvers have good performance in solving large-scale topology optimization problems.However,in unconventional cases same as crashworthiness design in which there is numerical noise in the gradient information,the uses of these algorithms are unsuitable.The standard evolutionary algorithms can solve such problems since they don’t need gradient information.However,they have a high computational cost.This paper is based upon the idea of combining metaheuristics with mathematical programming to handle the probable noises and have faster convergence speed.Due to the ease of computations,the compliance minimization problem is considered as the case study and the artificial noise is added in gradient information.展开更多
文摘A mass-spring-damper linear oscillator with a limiting stop barrier is presented. Modeling non-smooth processes in mechanical engineering is a complex problem. It is especially for the systems with more than a single degree of freedom. But recent studies in dynamical systems have been applied to single degree of freedom systems. The vibrating system, consisting of an oscillator with amplitude of motion limited by a barrier, is known as a vibro-impact system. The amount of force and kinetic energy transferred to a barrier has an important application in designing of engineering systems that undergo the vibro-impact phenomenon. The results show the effect of changing restitution coefficient of a barrier on the amount of force and energy absorbed.
基金supported by the Automotive Engineering Research Center(AERC)of Iran University of Science and Technology(IUST)the Vehicle,Fuel and Environment Research Institute(VFERI)of The University of Tehran.
文摘A wavelet-based power management system is proposed in this paper with a combination of the battery and ultracapacitor(UC)hybrid energy storage system(HESS).The wavelet filter serves as a frequency-based filter for distributing the power between the battery and UC.In order to determine the optimal level of wavelet decomposition as well as the optimal activation power of the wavelet controller,an optimization procedure is established.The proposed frequency-based power management system moderates the usage of battery current,consequently improving its lifetime.Compared with the conventional threshold-based power management systems,the proposed system has the advantage of enhanced battery and UC power management.A LiFePO4 battery is considered and its life loss is modeled.As a case study,an electric motorcycle is evaluated in the federal test procedure(FTP)driving cycle.Compared with a conventional energy storage system(ESS)and a state of available power(SoP)management systems,the results show an improvement for the battery lifetime by 115%and 3%,respectively.The number of battery replacements is increased,and the energy recovery is improved.The 10-year overall costs of the proposed HESS strategy using wavelet are1500 dollars lower,compared with the ESS.
文摘This paper presents new hybrid methods for the identification of optimal topologies by combining the teaching-learning based optimization(TLBO)and the method of moving asymptotes(MMA).The topology optimization problem is parameterizing with a low dimensional explicit method called moving morphable components(MMC),to make the use of evolutionary algorithms more efficient.Gradient-based solvers have good performance in solving large-scale topology optimization problems.However,in unconventional cases same as crashworthiness design in which there is numerical noise in the gradient information,the uses of these algorithms are unsuitable.The standard evolutionary algorithms can solve such problems since they don’t need gradient information.However,they have a high computational cost.This paper is based upon the idea of combining metaheuristics with mathematical programming to handle the probable noises and have faster convergence speed.Due to the ease of computations,the compliance minimization problem is considered as the case study and the artificial noise is added in gradient information.
