基于音频特征的工程车辆工况识别研究

高效率地使用工程车辆是工程项目管理中节约成本的有效方法，无人监管环境下工程车辆的工况识别，是实现工程车辆高效率使用的有效手段。目前以GPS等技术为核心的车辆智能管理系统未对工程车辆进行工况识别，提出一种基于GRU循环神经网络的工程车辆工况识别方法，通过对工程车辆在不同工况下产生的音频信号进行分析，从中提取Mel倒谱系数作为主要特征，构建GRU循环神经网络模型进行训练和识别。实验结果表明，该方法可以实现对工程车辆工况的有效识别。     

Multi-color Q-switched of neodymium-doped all-fiber laser based on tungsten disulfide saturable absorber

Journal of Materials Science: Materials in Electronics - In this paper, a Q-switched and three-color operation of Neodymium-doped silica all-fiber laser is realized, in which, a few-layer...     

Identification of active sites in CO2 activation on MgO supported Ni cluster

In this work, initial activation mechanism of CO₂ over MgO supported Ni catalysts has been systematically studied through the periodic DFT calculations. In addition, the role of metal cluster, interface and support for CO₂ activation is investigated and the active site is identified. CO₂ is most favored to be activated on the interface instead of neither Ni cluster nor MgO support. The effective energy for this process is around 0.67 eV, and the dissociation of CO₂ (0.62 eV) is the rate-determining step, since it requires much higher energy than that of the CO₂ adsorption process (0.05 eV). Thus, the interface between metal cluster and support plays a key role for C=O bond activation. Moreover, CO1 is preferred to be adsorbed on the Ni cluster, while the O1 is likely to bind on Mg atom of support. To illustrate the adsorption behavior of CO₂ at different sites, the Mulliken atomic charge and electron density difference have been calculated. It was found that the total amount of electron gain for CO₂ binding at different sites follows the order of Interface (−0.03 e) < MgO support (−0.05 e) < Ni cluster (−0.07 e), and effective energy barrier rises linearly with the increase of electron gain of CO₂ binding at different sites. In addition, electron gain of oxygen atom O1 and oxygen atom O2 of CO₂ is the same for Ni cluster and MgO support, however, the electron gain of O1 and O2 is different for Interface. The difference of electron gain for two oxygen atoms shows the electron unbalance of CO₂ molecule, which is in favor of C=O activation. This study could shed some light on understanding the active sites of CO₂ thermal-catalytic activation over MgO supported Ni catalysts, and is helpful to elucidate the reaction on an atomic level.     

茅台镇酱香型白酒酿造环境中真菌菌群多样性分析

采用高通量测序技术结合数理统计软件分析方法，系统研究茅台镇酱香型白酒不同酿造轮次生产环境中的真菌菌群结构及特征。7 个轮次中共检测到4 个真菌门、212 个真菌属。根据各菌门、属的相对丰度，子囊菌门（Ascomycota）和担子菌门（Basidiomycota）是茅台镇酱香型白酒酿造环节中各酿造轮次的优势菌门，节担菌属（Wallemia）、复膜孢酵母属（Saccharomycopsis）为各轮次绝对优势真菌属。不同轮次环境样品中真菌组成结构的相似度较高，但其各轮次标志性真菌属存在差异。7 个酿造轮次共有相同真菌属56 个，在各轮次占主导地位，特征性真菌属在各轮次当中相对丰度和占比较小但种类丰富。Ascomycota最强节点为德巴利酵母属（Debaryomyces），Basidiomycota最强节点为红酵母属（Rhodotorula）。本研究揭示了茅台镇酱香型白酒不同酿造轮次环境中真菌菌群结构及其特征，为深入研究酱香型白酒酿造机理以及对酿造环境中微生物结构的解析提供了参考依据。     

Reaction Mechanism of Lithium-Ion Battery Fire Extinguishing Agent-Perfluorinated Hexanone Oxidizes Metal-Al

Fire Technology - The use of perfluorinated hexanone as a fire extinguishing agent for lithium-ion batteries (LIBs) has been steadily increasing in China in recent years. It successfully handles...     

Enable high reversibility of Fe/Cu based fluoride conversion batteries via interfacial gas release and detergency of garnet electrolytes

Garnet-type Ta-doped Li₇La₃Zr₂O₁₂ (LLZTO) electrolyte suffers from unstable chemical passivation under air exposure, responsible for the poor interfacial wettability and conductivity with Li metal. Instead of conventional methods to remove surface contaminants by mechanical polishing, acid etching and high temperature reduction, herein we propose a simple strategy of interfacial gas release and detergency to smartly convert Li₂CO₃ passivation layer into ion-conductive Li₃PO₄ domains at mild temperature (∼200 ℃). The in-situ formation of PH₃ vapor and its phosphorization enables a dramatic decrease of Li/garnet interfacial resistance down to 2 Ω cm² at room temperature (RT). The improved interfacial wettability and conductivity endow the symmetric cells with ultra-stable galvanostatic cycling over 1500 h and high critical current density of 2.6 mA/cm². The high coulombic efficiency of Li plating enables a high reversibility of solid-state NCM811/Li cells even under a low N/P ratio (∼4) and high cut-off voltage of 4.5 V at RT. The prototype of fluoride-garnet solid-state batteries are successfully driven as rechargeable system (rather than widely known primary battery) with high conversion capacity (400 ∼ 500 mAh/g) and high-rate performance (251.2 mAh/g at 3 C). This interface infiltration-detergency approach provides a practical solution to the achievement of high-energy solid-state Li metal batteries.     

PP–R管材及专用料的研究进展

综述了无规共聚聚丙烯(PP–R)管材及专用料的研究进展,重点从加工工艺和改性方法两个方面介绍了PP–R管材的研究开发现状。分析了PP–R管材研发存在的主要问题,提出了未来几年PP–R管材及专用料的研究开发方向。     

大林高架桥荷载试验分析

桥梁荷载试验是鉴定桥梁承载能力、评价桥梁现状的重要手段。为了保证桥梁使用的可靠性,检验桥梁结构的承载能力及其工作状况,对怀通高速24标大林高架桥进行静动载试验。文章介绍了大林高架桥荷载试验的测点布置、加载工况、测试结果及试验所需的试验荷载,测得控制截面的应力、挠度和频率等,并对该桥的使用性能做出评价。