一种用于机器人电池电量预测的Sarsa强化学习混合集成方法

建设数据高效互联的轨道交通车间已成为当前轨道交通装备行业转型发展的必然趋势。越来越多样化的移动运输机器人设备成为智能工厂数字化转型过程中的关键。准确预测机器人的电池电量可以指导控制中心提前采取科学合理的指令,确保物流运输链高效稳定运行。在本研究中,我们提出了一种基于状态-动作-奖励-状态-动作(Sarsa)强化学习算法的多学习器混合集成方法。首先,采用最大重叠离散小波变换(MODWT)对所测量的机器人原始电源电压数据进行预处理,可以显著降低时间序列数据的非平稳性和波动性。其次,利用门控循环单元(GRU)、深度置信网络(DBN)和长短期记忆(LSTM)对分解后得到的子序列进行预测建模。最后,使用Sarsa强化学习集成策略对上述三个基础预测器进行加权组合。所提出的Sarsa混合集成模型的性能在三个真实移动机器人功率数据集上得到验证。实验结果表明,运输机器人电池动力混合预测模型在鲁棒性、准确性和适应性方面具有竞争力。

Research on Active Safety Methodologies for Intelligent Railway Systems

Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.

准原位腐蚀研究Sc含量对Al-Zn-Mg合金微观组织及耐蚀性的影响

本文研究了添加Sc对Al-Zn-Mg合金耐蚀性的影响。在Al-Zn-Mg合金中添加Sc可以更有效地阻碍热处理过程中的再结晶,增强其力学性能。添加Sc的合金在晶界析出中表现出显著的不连续性。此外,在Sc含量为0.29 wt.%的合金中,η相在晶界上的分布间距最大,避免了细小连续的η相为腐蚀提供通道,从而增强晶间腐蚀抗性。剥落腐蚀试验和微观结构再结晶分析表明,添加Sc对再结晶有抑制作用,从而提高了耐腐蚀性。准原位腐蚀试验结果表明,Sc含量为0.29 wt.%的Al-Zn-Mg合金的未腐蚀织构呈先快速减少后迅速增多的趋势,由此提出了在Al-Zn-Mg合金腐蚀初期,添加Sc对改善其表面织构和提高其耐蚀性具有重要作用的结论。

The influence of the leading-edge angle of subgrade on the aerodynamic loads of a high-speed train in a wind tunnel

The purpose of this study is to establish the correlation between the boundary layer over the subgrade and the aerodynamic loads act-ing on the train model in conventional wind tunnel tests.Firstly,flow characteristics around the subgrade with different leading-edge angles(15°,30°and 45°)are investigated through the particle image velocimetry(PIV)experimental test method.Then,wind tunnel tests of the aerodynamic performance of a high-speed train are carried out.The results are compared with previous experimental data obtained by moving model tests.Results show that,due to the presence of a boundary layer,the pressure acting on the lower part of the train head decreases,while other locations are not significantly affected.This is the reason for the reduction of the aerodynamic drag and lift on the train.In addition,the reduction effects become more obvious when the thickness of the boundary layer increases.The experimental results obtained could serve as a calibration of aerodynamic forces for wind tunnel tests on high-speed trains.

Microstructure and Mechanical Properties of TiC-Reinforced Al–Mg–Sc–Zr Composites Additively Manufactured by Laser Direct Energy Deposition

In order to refine the microstructure and improve the performance of direct energy deposited(DED)additively manufactured Al–Mg–Sc–Zr alloy,TiC-modified Al–Mg–Sc–Zr composites were prepared by DED and the effect of TiC content on the microstructure and performance was studied.In the absence of TiC particle,the microstructure of Al–Mg–Sc–Zr alloy prepared by DED consisted of fine grains with average size of 8.36μm,and well-dispersed nano-Al;(Sc,Zr)particles inside the grains and Mg;Si phase along the grain boundaries.With the addition of 1 wt%TiC,the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became finer apparently compared with that without TiC;while the further increase of TiC content to 3 wt%,the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became coarser with appearance of a new kind of needle-like(Ti,Zr);Si;phase.Also,the addition of TiC decreased the porosity of Al–Mg–Sc–Zr prepared by DED.Simultaneously,after the addition of TiC,the tensile strength increased from 283.25 MPa to 344.98–361.51 MPa,and the elongation increased from 3.61%to 9.58–14.10%.The potential mechanism of the microstructure evolution and strength improvement was discussed.This research will provide new insights into the available metal matrix composites by laser additive manufacturing(LAM).

The Theoretical and Experimental Analysis of the Maximal Information Coefficient Approximate Algorithm

In the era of big data,correlation analysis is significant because it can quickly detect the correlation between factors.And then,it has been received much attention.Due to the good properties of generality and equitability of the maximal information coefficient(MIC),MIC is a hotspot in the research of correlation analysis.However,if the original approximate algorithm of MIC is directly applied into mining correlations in big data,the computation time is very long.Then the theoretical time complexity of the original approximate algorithm is analyzed in depth and the time complexity is n2.4 when parameters are default.And the experiments show that the large number of candidate partitions of random relationships results in long computation time.The analysis is a good preparation for the next step work of designing new fast algorithms.

底部导流板对高速列车气动减阻的影响

转向架和车下设备区域是高速列车气动阻力的主要来源之一,基于此,本文提出一种安装于转向架舱前后端的小型导流板装置,以改善列车的底部流动、减小列车的气动阻力.采用IDDES方法对是否安装底部导流板的不同列车模型开展非定常数值仿真,并对导流板的减阻效果和作用机理进行分析.结果表明:底部导流板可以将列车底部高速气流导向地面,减小气流对转向架及车下设备的冲击作用,从而产生显著的气动减阻效果.此外,还讨论了底部导流板不同安装位置对减阻效果的影响,最终得到了实现整车减阻约12%的一种最佳安装方式.同时,导流板还能够减小底部流场在展向上的影响范围,减小列车风,这对铁路沿线工人和平台等候乘客的安全具有更高保障.本研究为高速列车气动减阻提供了新思路、新方法。对节能减耗、可持续发展等具有重要意义.

Microstructures and Mechanical Properties of Al-Mg-Sc-Zr Alloy Additively Manufactured by Laser Direct Energy Deposition

An Al-Mg-Sc-Zr alloy was additively manufactured by laser direct energy deposition(DED)under different laser powers,and the microstructures and mechanical properties of the as-deposited samples were investigated.The samples showed a fully equiaxed grain structure with grain sizes of 2–30μm.Most of the blocky primary Al3(Sc,Zr)-precipitated phases(<5μm)were arranged along the grain boundaries.A small amount of fine granular secondary Al3(Sc,Zr)phases(<0.5μm)were precipitated owing to the cyclic heat treatment during the DED forming process.According to the EBSD(Electron backscatter diffraction)results,the texture index and strength of the sample were only slightly greater than 1,indicating that the material structure exhibited a certain but not obvious anisotropy.The sample in the horizontal direction had better yield strength,tensile strength,and elogation properties(399.87 MPa,220.96 MPa,9.13%)than that in the building direction(385.40 MPa,219.40 MPa,8.24%),although the sample in the〈XOZ〉plane had the finest equiaxed grains.The ductility of the〈XOZ〉sample deteriorated as the number of pores increased.