Sampling Consensus of 2nd-Order Multi-Agent Systems Based on Time-Varying Topology北大核心CSCD

基于速度一致位移差保持不变的一致性概念,研究了二阶多智能体系统在时变拓扑下的采样一致性问题。首先,引入虚拟领导者,将具有时变拓扑结构的多智能体系统的采样一致性问题转换为误差系统的采样控制稳定性问题。其次,通过预估采样误差,研究采样误差对系统达到一致性的影响。最后,应用Lyapunov稳定性理论,分析所构造的误差系统的稳定性,并给出该误差系统最终稳定的充分条件。数值仿真结果验证了理论分析的有效性和正确性。     

材料断口中的分形(英文)

分形几何(Fractal geometry)是近年来出现的一门应用数学分支。本文简要介绍了分形在材料断裂表面分析中的应用概况,并叙述了本文作者关于“延性断裂韧性与断裂表面的分形”研究工作。如果继续深入研究,将可从材料破坏的断口上直接分析并推知其断裂特性,从而为材料的失效分析提供一种简便而实用的新方法。     

滑模-矢量控制变频调速系统

本文介绍一种滑模-矢量控制系统。在矢量控制的基础上,采用滑模-PI控制方案,使系统获得优良的控制性能,克服了稳态时的震颠现象。系统由2片8031单片机和SPWM—GTR逆变器组成。在3kW异步电动机上进行的试验结果表明,该系统具有优良的动静态性能和较强的鲁棒性。     

用最小均方误差对数短时谱幅值估计法增强语音信号

本文主要研究语音增强系统在短时频域内,以对数最小均方误差作为语音幅值估计的准则.对含噪语音进行消噪处理。首先推导了公式,并从理论上作了分析研究.在此基础上作了大量实验,与类似的最小均方误差短时谱幅值估计法(MMSE STSA)作了性能比较.实验结果表明,由MMSE LOG-STSA增强方法得到的语音输出的质量优于由MMSA STSA方法得到的质量.语音的失真度和清晰度均有显著改善,同时大大降低了语音中的“音乐噪声”.     

细基江蓠原变型与细基江蓠繁枝变型制取琼胶的比较研究

本文采用三种碱处理方法对细基江蓠原变型、混养细基江蓠繁枝变型和单养细基江蓠繁枝变型进行了对比研究。得出"中温浓碱法"为提高三种江蓠琼胶凝胶强度的较好工艺,而"常温浓碱法"的产率较好."中温浓碱法"三种江蓠琼胶的产率及凝胶强度分别为(次序同上,下同):38.6%、691g/cm²、13.1%、637g/cm²,13.9%、557g/cm²,"常温浓碱法",三种江蓠琼胶的产率及凝胶强度分别是:47.6%、509g/cm²,19.5%、414g/cm²,25.9%,326g/cm²。     

第II类双边拆卸线平衡问题建模与优化

报废汽车体积大,废弃物污染大,拆卸过程复杂,将作业任务均衡分配难。为此,本文对工作站数量确定的双边拆卸线平衡问题进行研究,建立问题数学模型,设计一种变邻域蛙跳算法。所提算法在寻优过程中采用变邻域搜索提高族群局部搜索效率;引入个体学习机制加快精英个体进化速度;提出基于二分法的节拍时间调整策略加快对最优节拍的搜索。最后,通过算例对算法性能进行验证并通过实例说明任务在拆卸线上平衡分配的重要性。     

Multiple attribute decision-making method based on projection model for dual hesitant fuzzy set

Fuzzy Optimization and Decision Making - In the decision-making process, retaining the original data information has become a most crucial step. Dual hesitant fuzzy sets (DHFS), which can reflect...     

Structure,trend and prospect of operational research: a scientific analysis for publications from 1952 to 2020 included in Web of Science database

As an important research direction, operational research (OR) has always attracted scholars worldwide. We study the structure, trend and prospect in the OR field by conducting a bibliometric analysis of publications in the period of 1952–2020, which are included in the Web of Science (WoS) database. Using three effective bibliometric tools, namely, VOS viewer, CiteSpace, and Bibliometrix, a total of 5,353 publications were retrieved to show clear visual results using a series of scientific analyses. First, a performance analysis revealed the basic characteristics of publications considering the type distribution, annual trend, quantity and quality. Then, a cooperation analysis presented the influential countries/regions and showed the relationships among countries/regions, institutions and authors during different periods based on bibliometric indicators and co-authorship networks. Moreover, a keyword analysis was conducted to investigate the hot topics and development of the OR field, using co-occurrence analysis, timeline view analysis and evolution analysis. Finally, we discussed the implications and limitations, and summarized the main findings. This study hopes to provide important and valuable references for future research on the OR field.

     

New Results on Generalized $c$-Distance Without Continuity in Cone $b$-Metric Spaces over Banach Algebras

In this work, some new fixed point results for generalized Lipschitz mappings on generalized $c$-distance in cone $b$-metric spaces over Banach algebras are obtained, not acquiring the condition that the underlying cone should be normal or the mappings should be continuous. Furthermore, the existence and the uniqueness of the fixed point are proven for such mappings. These results greatly improve and generalize several well-known comparable results in the literature. Moreover, some examples and an application are given to support our new results.