关键词： 图像识别   数学公式   文本检测   字符分割  

摘要： 针对数学公式识别难问题,基于印刷体根号的几何特征,定义首一特征线概念,并据此给出印刷体数学公式中根号的识别算法,基于Matlab软件编程实现该算法.结果表明该算法能有效识别一维印刷体数学公式中的根号,识别正确率达到100%.

关键词： 计量标准   数学模型   稳定性   预测  

摘要： 对计量标准的稳定性进行监控是计量管理的重要工作之一。《计量标准考核规范》推荐的考核方法均为事后监控,追溯不合格结果发生的时间及其影响会给管理人员增加极大的工作量。基于参考计量标准历史数据分析,运用数学模型算法,比较了最小二乘法、一阶差分指数平滑法和自回归(AR)模型预测法三种方法预测计量标准的稳定性变化趋势,并讨论了三种模型在实际应用中的区别。

关键词： Algebraic evolutionary algorithms   Combinatorial search spaces   Algebraic evolutionary computation  

摘要： A popular trend in evolutionary computation is to adapt numerical algorithms to combinatorial optimization problems. For instance, this is the case of a variety of Particle Swann Optimization and Differential Evolution implementations for both binary and permutation-based optimization problems. In this paper, after highlighting the main drawbacks of the approaches in literature, we provide an algebraic framework which allows to derive fully discrete variants of a large class of numerical evolutionary algorithms to tackle many combinatorial problems. The strong mathematical foundations upon which the framework is built allow to redefine numerical evolutionary operators in such a way that their original movements in the continuous space are simulated in the discrete space. Algebraic implementations of Differential Evolution and Particle Swarm Optimization are then proposed. Experiments have been held to compare the algebraic algorithms to the most popular schemes in literature and to the state-of-the-art results for the tackled problems. Experimental results clearly show that algebraic algorithms outperform the competitors and are competitive with the state-of-the-art results.

关键词： Rotors   Doubly fed induction generators   Stators   Mathematical model   Observers   Wind speed   Wind turbines   Field-oriented control (FOC)   position-sensorless algorithm   rotor-tied doubly fed induction generator (DFIG)   wind energy conversion system (WECS)  

摘要： The rotor-tied doubly fed induction generator (DFIG) configuration has the advantages of higher efficiency and reduced size as compared to stator-tied DFIG for the same power rating. This article presents a mathematical modeling of rotor-tied DFIG in rotor-flux reference frame considering the observer at stationary reference frame. Furthermore, position-sensorless algorithm for the rotor-tied DFIG is proposed to estimate the rotor position, which is based on simple algebraic equations. The proposed position-sensorless algorithm is independent of critical machine parameters which makes the algorithm robust against parameter variations. The algorithm works accurately for different wind speed conditions and thus, useful for wind energy conversion system (WECS) which necessitates the constant frequency operation against variable wind speed. The effectiveness of the proposed position-sensorless algorithm is verified using hardware-in-loop (HIL) set up. OPAL-RT and STM32F407VG micro controller are used in the HIL. Simulation and experimental results for a 250 kW rotor-tied DFIG-based WECS are shown under different wind speed conditions.

关键词： Axial algebra   Nonassociative algebra   Majorana algebra   Finite groups   Algorithm  

摘要： An axial algebra A is a commutative non-associative algebra generated by primitive idempotents, called axes, whose adjoint action on A is semisimple and multiplication of eigenvectors is controlled by a certain fusion law. Different fusion laws define different classes of axial algebras. Axial algebras are inherently related to groups. Namely, when the fusion law is graded by an abelian group T, every axis a leads to a subgroup of automorphisms T-a of A. The group generated by all T-a is called the Miyamoto group of the algebra. We describe a new algorithm for constructing axial algebras with a given Miyamoto group. A key feature of the algorithm is the expansion step, which allows us to overcome the 2-closedness restriction of Seress's algorithm computing Majorana algebras. At the end we provide a list of examples for the Monster fusion law, computed using a MAGMA implementation of our algorithm. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Grid-connected photovoltaic plants   Modeling   Optimization   Genetic algorithm  

摘要： The increasing penetration of photovoltaic (PV) technology calls for the development of an effective method for optimization of grid-connected photovoltaic power plants. This paper presents a simultaneous optimization method of ten important design parameters of a PV plant, including the module power, inverter sizing, support structure dimensions, cable losses, module orientation and row spacing. A mathematical PV performance model taking into account the important effects and losses and an economic cost model were developed and presented in detail. The objective function is the internal rate of return and the optimization is performed by a genetic algorithm. The results show that the proposed models and method are capable to optimize the grid-connected PV plant and provide reliable results after a 6-7 min calculation time. The method was demonstrated in detail for a Hungarian location, including the losses and cost structure of the optimal plant configuration. The optimization was also performed for 5 additional sites around the world to assess the effect of location and meteorology. The impact of the decreasing PV module prices on the optimal design is calculated to identify the expected future trends in PV plant design. The presented optimization method can be utilized to facilitate the optimal design of commercial PV plants and for research purposes.

关键词： Assembly line balancing   multi-manned workstations   mixed-integer programming   tabu search algorithm   assignment restrictions  

摘要： A multi-manned assembly line is a set of workstations where task operations can be performed on multiple sides of the line. Such assembly lines are important for large products, such as buses, cars and trucks. In this study, a mathematical model for multi-manned assembly lines with assignment restrictions is proposed. The purpose of the mathematical model is to minimize the total number of workers and open multi-manned workstations along the line for a given cycle time simultaneously under various assignment restrictions. The model provides a more realistic situation for multi-manned assembly line problems. The tabu search algorithm (TSA) is also used to solve the problem. The performances of both methods on well-known data-set problems are analysed. Based on the computational experiments, the performance of the proposed TSA is compared with the mathematical model solutions on various problem instances. The experimental results verify the effectiveness and efficiency of the proposed TSA.

关键词： welding flow-shop scheduling problem   non-dominated sorting Genetic Algorithm III   total tardiness   machine interaction effect   setup time  

摘要： This paper addresses a bi-objective welding shop scheduling problem (BWSSP) aiming to minimise the total tardiness and the machine interaction effect. The BWSSP is a special flow-shop scheduling problem (FSP) which is characterised by the fact that more than one machine can process on one job at a certain stage. This study analyses the operation of a structural metal manufacturing plant, and includes various aspects such as job sequence, machine-number-dependent processing time, lifting up time, lifting down time and different delivery time. A novel mixed-integer programming model (MIPM) is established, which can be used to minimise the delayed delivery time and the total machine interaction effect. One machine interaction effect formula is given in this paper. In order to solve this BWSSP, an appropriate non-dominated sorting Genetic Algorithm III (NSGAIII), embedded with a restarted strategy (RNSGAIII), is proposed. The restarted strategy, which can increase the diversity of the solutions, will be triggered with a restart probability. Following the iterative process, an effective strategy is applied to reduce the interaction effect penalty, on the premise that the makespan will remain unchanged. Total five algorithms, namely NSGAII, NSGAIII, harmony search algorithm (HSA), strength Pareto evolutionary algorithm (SPEA2), and RNSGAIII are utilised to solve this engineering problem. Numerical simulations show that the improved RNSGAIII outperforms the other methods, and the Pareto solution distribution and diversity, in particular, are significantly improved.

关键词： 区块链技术   社会信用体系   数学算法   社会信用机制   全程追溯   应用场景   公开透明   达成共识  

摘要： 来源:《人民论坛》智慧社会来临对传统社会信用体系提出了挑战,为新型社会信用体系的产生提供了技术基础和应用场景。在此背景下,区块链技术的发展催生了一种新型社会信用机制,即系统信用,它通过构建一种可信的技术系统,保障信息的公开透明、全程追溯和不可篡改,在机器之间建立"信任"网络,通过数学算法为社会成员创造信用和达成共识。

关键词： 随机事件   主成分算法   数学化  

摘要： 随机事件,在《概率论与数理统计》课程中,是很重要的基础知识点,但在教学过程中一直没有引起足够的重视。但在现实问题转化为数学问题的过程中,随机事件是首要的第一步。在该文中,将讨论随机事件在实际问题数学化过程中的重要性及其熟练地学习和掌握如何去把现实问题用随机事件这种数学的语言表述出来,并且,还讨论了其在主成分算法中的应用。