关键词： 核心素养   初中数学   有理数加法   同类思维   直接探索  

摘要： 基于核心素养发展的内涵和引领,走学生最近发展区,借助学生熟悉的事例和情感,找准切入点,由浅入深,化难为易,践行知识形成知、情、意、行的心理认知过程。进行有理数加法法则的感知、想象、推理、归纳、记忆、和应用。为新知——有理数加法的学习和感知提供基础,由浅入深,化难为易,以提高教学效果和学习的兴趣。

关键词： Bayesian network (BN)   Parameters learning   Scarce data   CPEL algorithm   Autonomous mission decision-making  

摘要： In this paper, a constrained parameter evolutionary learning (CPEL) algorithm for Bayesian network (BN) parameters learning under scarce data is proposed, which can be applied to UAV autonomous mission decision-making. In detail, firstly qualitative domain knowledge is employed into BN parameters learning process to reduce the parameter search space where two types of qualitative domain knowledge with experts' confidence are presented;and then evolutionary strategy is introduced into the process to avoid the problem that classical learning technique falls into local optimum easily in which the special encoding for the BN parameters is presented and some evolutionary strategies are discussed. Moreover, the global convergence of the proposed algorithm is proven. According to numerical experiments, it's demonstrated that the CPEL algorithm has better accuracy and timeliness performance than the classical EM algorithm under the same condition. Additionally, a case study of the proposed algorithm in UAV autonomous mission decision-making has been conducted, showing that CPEL algorithm can satisfy the need of UAV autonomous mission decision-making in a complex dynamic environment.

关键词： Aircraft maintenance scheduling   Hangar parking layout planning   Mixed-integer linear programming   Event-based model   Rolling horizon approach  

摘要： An aircraft hangar maintenance scheduling problem is studied, motivated by the aircraft heavy maintenance conducted in a hangar operated by an independent maintenance service company. The aircraft hangar maintenance scheduling problem in such context consists of determining a maintenance schedule with minimum penalty costs in fulfilling maintenance requests, and a series of hangar parking plans aligned with the maintenance schedule through the planning period. A mixed-integer linear programming (MILP) mathematical model, integrating the interrelations between the maintenance schedule and aircraft parking layout plans, is presented at first. In the model, the variation of parking capacity of the maintenance hangar and the blocking of the aircraft rolling in and out path are considered. Secondly, the model is enhanced by narrowing down the domain of the time-related decision variables to the possible rolling in and out operations time of each maintenance request. Thirdly, to obtain good quality feasible solutions for large scale instances, a rolling horizon approach incorporating the enhanced mathematical model is presented. The results of computational experiments are reported, showing: (i) the effectiveness of the event-based discrete time MILP model and (ii) the scalability of the rolling horizon approach that is able to provide good feasible solutions for large size instances covering a long planning period. (C) 2018 Elsevier Inc. All rights reserved.

关键词： Mathematical programming  

摘要： This paper addresses one of the most challenging issues in designing an efficient and sustainable ridesharing service: ridesharing market design. We formulate it as a fair cost allocation problem through the lens of the cooperative game theory. A special property of the cooperative ridesharing game is that its characteristic function values are calculated by solving an optimization problem. Several concepts of fairness are investigated and special attention is paid to a solution concept named nucleolus, which aims to minimize the maximum dissatisfaction in the system. Due to its computational intractability, we break the problem into a master-subproblem structure and two subproblems are developed to generate constraints for the master problem. We propose a coalition generation procedure to find the nucleolus and approximate nucleolus of the game. Experimental results showed that when the game has a non-empty core, in the approximate nucleolus scheme the coalitions are computed only when it is necessary and the approximate procedure produces the actual nucleolus. And when the game has an empty core, the approximate nucleolus is close to the actual one. Regardless of the emptiness of the game, our algorithm needs to generate only a small fraction (1.6%) of the total coalition constraints to compute the approximate nucleolus. The proposed model and results nicely fit systems operated by autonomous vehicles. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Unrelated parallel machine scheduling   Scheduling with a common server   Simulated annealing   Tabu search   Sequence-dependent setup times   Dispatching rule  

摘要： Parallel machine scheduling problems with common servers have many industrial applications. In this paper, we study a generalized problem of scheduling with a common server, which is the unrelated parallel machine scheduling problem with sequence-dependent setup times and machine eligibility restrictions. The objective function involves the minimization of the total weighted tardiness. A mixed integer linear programming (MILP) model is proposed to solve this complex problem. Due to the NP hardness of the problem, tabu search (TS) and simulated annealing (SA) algorithms are proposed. The initial solutions of the algorithms are obtained by a modified apparent tardiness cost with setups (ATCS) dispatching rule. The proposed algorithms are compared using a randomly generated data set. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： power factor compensation   non-sinusoidal circuits   geometric algebra   evolutionary algorithms  

摘要： Non-linear loads in circuits cause the appearance of harmonic disturbances both in voltage and current. In order to minimize the effects of these disturbances and, therefore, to control the flow of electricity between the source and the load, passive or active filters are often used. Nevertheless, determining the type of filter and the characteristics of their elements is not a trivial task. In fact, the development of algorithms for calculating the parameters of filters is still an open question. This paper analyzes the use of genetic algorithms to maximize the power factor compensation in non-sinusoidal circuits using passive filters, while concepts of geometric algebra theory are used to represent the flow of power in the circuits. According to the results obtained in different case studies, it can be concluded that the genetic algorithm obtains high quality solutions that could be generalized to similar problems of any dimension.

关键词： Landsat   改进的归一化差异水体指数   图像分割   数学形态学   海岸水边线  

摘要： 海岸线变迁研究在海岸带研究中具有重要意义,提取遥感影像成像时刻的水边线(瞬时海岸水边线)是提取海岸线的关键。该文以海南省文昌市、琼海市2010年的Landsat TM5影像为数据源,研究多种图像阈值分割方法在海岸水边线提取中的最优算法及其区域适应性;采用多种数学形态学算子及其结构元素重构方法对结果进行碎斑块等噪声处理,分析比较在典型区域上的表现力;最后从阈值选取难易程度、提取海岸水边线的精度、误差来源机理方面进行整体评价分析。结果表明:改进的归一化差异水体指数(Modified Normalized Difference Water Index,MNDWI)在海岸水边线提取中显示了明显的优势,主要表现在较好的海陆对比度差异、较少的噪声影响以及在复杂环境下的区域普适性等方面;采用3×3结构元素的数学形态学开运算进行后处理,在保证海岸水边线位置精度的基础上,可对近海鱼塘、山体阴影以及反射特性比较弱的植被等造成的误提碎斑块进行合理去除;河口及淤泥质岸线、人工养殖区及生物质岸线处是图像阈值分割法岸线提取的主要偏差来源区域。