科创中国

Due to the insufficiency of utilizing knowledge to guide the complex optimal searching, existing genetic algorithms fail to effectively solve excavator boom structural optimization problem. To improve the optimization efficiency and quality, a new knowledge-based real-coded genetic algorithm is proposed. A dual evolution mechanism combining knowledge evolution with genetic algorithm is established to extract, handle and utilize the shallow and deep implicit constraint knowledge to guide the optimal searching of genetic algorithm circularly. Based on this dual evolution mechanism, knowledge evolution and population evolution can be connected by knowledge influence operators to improve the configurability of knowledge and genetic operators. Then, the new knowledge-based selection operator, crossover operator and mutation operator are proposed to integrate the optimal process knowledge and domain culture to guide the excavator boom structural optimization. Eight kinds of testing algorithms, which include different genetic operators, are taken as examples to solve the structural optimization of a medium-sized excavator boom. By comparing the results of optimization, it is shown that the algorithm including all the new knowledge-based genetic operators can more remarkably improve the evolutionary rate and searching ability than other testing algorithms, which demonstrates the effectiveness of knowledge for guiding optimal searching. The proposed knowledge-based genetic algorithm by combining multi-level knowledge evolution with numerical optimization provides a new effective method for solving the complex engineering optimization problem.

Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain,e.g.,pure mechanical systems.Only little work has been performed on the problem of multi-domain simulation stability influenced by algebraic loops.In this paper,the algebraic loop problem is studied by a composite simulation method to reveal the internal relationship between simulation stability and system topologies and simulation unit models.A stability criterion of multi-domain composite simulation is established,and two algebraic loop compensation algorithms are proposed using numerical iteration and approximate function in multi-domain simulation.The numerical stabilized algorithm is the Newton method for the solution of the set of nonlinear equations,and it is used here in simulation of the system composed of mechanical system and hydraulic system.The approximate stabilized algorithm is the construction of response surface for inputs and outputs of unknown unit model,and it is utilized here in simulation of the system composed of forging system,mechanical and hydraulic system.The effectiveness of the algorithms is verified by a case study of multi-domain simulation for forging system composed of thermoplastic deformation of workpieces,mechanical system and hydraulic system of a manipulator.The system dynamics simulation results show that curves of motion and force are continuous and convergent.This paper presents two algorithms,which are applied to virtual reality simulation of forging process in a simulation platform for a manipulator,and play a key role in simulation efficiency and stability.

高中物理教科书中编入了诸多中国传统文化的素材.通过以应用比较广泛的三个版本的物理教科书中的相关内容为研究对象,进行分析和解读,认为教科书在引入传统文化时,应更多地关注其与学科内容间的联系,充分利用古诗词的魅力,并以多种方式进行展示,将传统文化元素与物理学知识更好地融合,发挥传统文化对物理课程的教育教学功能.