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RVVB导线过电流诱发短路起火及迸溅熔珠特征试验研究

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中国人民警察大学学报 2024年第6期40卷 52-56页

作者：刘学屹天津市滨海新区消防救援支队天津300450

为研究RVVB导线过电流诱发短路故障发生过程和迸溅熔珠典型特征,搭建220 V电压条件下导线过电流诱发短路故障装置,利用视频影像技术分析短路发生过程,统计初次短路发生时间和短路持续时间,收集迸溅熔珠并分析其形貌和典型组织特征。结... 详细信息

为研究RVVB导线过电流诱发短路故障发生过程和迸溅熔珠典型特征,搭建220 V电压条件下导线过电流诱发短路故障装置,利用视频影像技术分析短路发生过程,统计初次短路发生时间和短路持续时间,收集迸溅熔珠并分析其形貌和典型组织特征。结果表明:导线由内及外受热时,PVC绝缘层发生热解,导线发生初次短路时间与电流值存在指数递减关系。迸溅熔珠根据形貌可分为圆珠状、连接珠状、凹坑状、半珠状、连接半珠状、连接棒状及连接尖状,其金相组织可分为4类。试验结果可为火灾调查提供参考。

关键词：电气火灾过电流短路故障迸溅熔珠

典型水深与海底介质条件下的OBC/OBN多分量地震数据波型特征

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石油物探 2024年第1期63卷 45-60页

作者：王腾飞刘学义程玖兵同济大学海洋地质国家重点实验室上海200092

海底电缆或海底节点(OBC/OBN)多分量地震是开展海上复杂油气藏勘探的重要手段之一。由于地震波与自由表面及海底界面的互相作用,海底多分量地震记录中波型成分十分复杂。调查其中各类信号与噪声的形成机制及其影响,可为后续数据处理与... 详细信息

海底电缆或海底节点(OBC/OBN)多分量地震是开展海上复杂油气藏勘探的重要手段之一。由于地震波与自由表面及海底界面的互相作用,海底多分量地震记录中波型成分十分复杂。调查其中各类信号与噪声的形成机制及其影响,可为后续数据处理与解释提供关键依据。针对海底多分量地震观测条件下潜在的波场信号,按照不同水深与典型海底沉积物性质构建代表性的弹性参数模型,利用谱元法合成OBC/OBN多分量地震记录,分析各类波型成分的表现特征,揭示水深和海底介质特性对波场运动学及动力学特征的影响。通过与东海浅水区和南海深水区海底地震仪(OBS)采集的实际地震数据的对比分析,确认了水深与海底介质条件对表面多次波与海底界面波的调控机理,为海底多分量地震数据处理方法研究与技术应用提供有益的指导。

关键词：海底多分量地震海底界面效应 P-S模式耦合自由表面多次波海底地震仪 OBC/OBN

Temperature field test and prediction using a GA-BP neural network for CRTS Ⅱ slab tracks

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Railway Engineering Science 2023年第4期31卷 381-395页

作者： Dan liu Chengguang Su Rongshan Yang Juanjuan Ren xueyi liu Highway School Chang’an UniversityXi’an 710064China China Railway First Survey and Design Institute Group Co.Ltd.Xi’an 710043China MOE Key Laboratory of High-Speed Railway Engineering Southwest Jiaotong UniversityChengdu 610031China College of Transportation Engineering Chang’an UniversityXi’an 710064China

The CRTS Ⅱ slab track, which is connected in a longitudinal direction, is one of the main ballastless tracks in China, with approximately 7365 km of operational track. Temperature loading is a very vital factor leading to slab track damages such as warping and cracking. While existing research on temperature distribution rests on either site tests in special environments or theoretical analysis, the long-term temperature field characteristics are not clear. Therefore, a long-term temperature field test for the CRTS Ⅱ slab track on bridge-subgrade transition section was conducted to analyze the temperature field. A GA-BP(genetic algorithm optimized back propagation) neural network was trained on the test data to predict the temperature field. The vertical and lateral temperature distributions in four typical days were carried out. We found that the temperature along the track was distributed in a nonlinear manner. This was particularly distinct in the vertical direction for depths of less than 300 mm. The highest and lowest daily temperatures and the daily range of the temperature were analyzed. With the increasing depth, the daily highest temperatures and range of the temperature were smaller, the daily lowest temperatures were higher, and the time corresponding to this peak value appeared later in the day. Both the highest and lowest daily temperature could be predicted using the GA-BP neural network, though the accuracy in predicting the highest temperature was higher than that in predicting the lowest temperature.

关键词： Ballastless track Long-term test Temperature distribution Correlation analysis Neural network

Subgrains and boron distribution of low carbon bainitic steels

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Journal of University of Science and Technology Beijing 2005年第5期12卷 406-409页

作者： Xuemin Wang Bing Cao Chengjia Shang xueyi liu Xinlai He Dept of Materials Physics University of Science and Technology Beijing Beijing 100083 China Editorial Board of the Journal of University of Science and Technology Beijing Beijing 100083 China

The structure variation of deformed austenite during the relaxation stage after deformation at various temperatures in an Nb-B ultra low carbon bainitic steel and Fe-Ni alloy was studied by the thermo-simulation. Optical microscope and TEM were applied to analyze the microstructure after RPC （Relaxation-precipitation-controlling phase transformation technique） and the evolution of dislocation configuration. The particle tracking autoradiography （PTA） technique, revealing the distribution of boron, was employed to show the change of boron segregation after different relaxation times. The results indicate that during the relaxation stage the recovery occurs in the deformed austenite, the dislocations rearrange and subgrains form. During the subsequent cooling the boron will segregate at the boundaries of subgrains.

关键词： RPC technique PTA subgrains boron distribution

Experimental study of temperature gradient in track slab under outdoor conditions in Chengdu area

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Journal of Modern Transportation 2014年第3期22卷 148-155页

作者： Pingrui Zhao xueyi liu Guan liu MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong University

Temperature is one of the important loads for designing slab track. The characteristic of slab track tem- perature varies greatly with different regional climates. In this work, a bi-block slab track model was built under outdoor conditions in Chengdu area; the statistical characteristic of temperature gradient in track slab and the relationship between temperature gradient and surface air temperature were tested and analyzed. The results show that the track slab temperature gradient will vary periodically according to the surface air temperature, and show a clear nonlinearity along the height direction. The temperature gradient distribution is extremely uneven： the temperature gradient in the top part of the track slab is larger than that in the bottom part; the most frequently occurring temperature gradient of the track slab is around -3.5 ℃/m and more than 75 % locates in the level -10 to 10 ℃/m; concrete with a relatively good heat exchange condition with the surrounding air has a narrower band distribution. In addition, the frequency distribution histogram should exclude the time zone from 00：00 to 06：00 because there is almost no traffic in this period. The amplitude of track slab temperature variation is obviously lower than that of the air temperature variation, and the former is approximately linear with the latter.

关键词： Slab track Track slab - Temperature gradient Temperature field Surface air temperature

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基于混合粒子群算法的配电网故障重构研究

电气应用 2024年第4期43卷 63-69页

作者：陈壮胡亚琼王风华刘学义刘印国网河南省电力公司桐柏县供电公司河南南阳473000

为了实现含分布式电源的配电网络故障时的恢复供电,在分析粒子群算法基本原理与配电网络结构模型的基础上,提出一种基于混沌映射改进的自适应混合粒子群算法。将压缩因子与自适应权重引入粒子群算法,并借鉴遗传算法中的杂交与自然选择思... 详细信息

为了实现含分布式电源的配电网络故障时的恢复供电,在分析粒子群算法基本原理与配电网络结构模型的基础上,提出一种基于混沌映射改进的自适应混合粒子群算法。将压缩因子与自适应权重引入粒子群算法,并借鉴遗传算法中的杂交与自然选择思想,在每次迭代中根据杂交率选取一定粒子进行两两杂交,把每次迭代结果中优秀的一半替换差的一半,并对适应度值良好的粒子进行Logistic混沌优化。接入分布式电源的IEEE 33节点算例,模拟不同算法进行故障重构。仿真测试结果体现出了改进算法具有更快的收敛速度与更好的稳定性。

关键词：配电网自动化故障重构 Logistic混沌优化混合粒子群算法遗传算法

浅析我国卫生政策对眼科日间手术推进过程的影响及具体实践

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现代医院 2024年第3期24卷 336-339页

作者：刘学一赵建国孙瑞强邓美玉王倩天津市眼科医院天津300020

随着国家医药卫生体制改革进入公立医院高质量发展新阶段,面对患者日益增长的就诊需求,医院规模化推行日间手术迫在眉睫。文章对我国日间手术相关的医政管理与医疗保障政策及影响进行了梳理,并以眼科专科医疗机构通过预住院模式规模化... 详细信息

随着国家医药卫生体制改革进入公立医院高质量发展新阶段,面对患者日益增长的就诊需求,医院规模化推行日间手术迫在眉睫。文章对我国日间手术相关的医政管理与医疗保障政策及影响进行了梳理,并以眼科专科医疗机构通过预住院模式规模化推行日间手术实例说明如何使用管理学工具突破日间手术推动过程瓶颈,并阐述日间手术规模化开展对医患双方的正面作用。

关键词：日间手术政策影响眼科实践管理学工具预住院模式

Differences between soybean genotypes in physiological response to sequential soil drying and rewetting

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The Crop Journal 2014年第6期2卷 366-380页

作者： Md Mokter Hossain xueyi liu Xusheng Qi Hon-Ming Lam Jianhua Zhang School of Life Sciences and Center for Soybean Research of the State Key Laboratory of Agrobiotechnology The Chinese University of Hong KongShatin Institute of Economic Crops Shanxi Academy of Agricultural Sciences Institute of Crop Science Gansu Academy of Agricultural Sciences

Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physiological traits of soybean genotypes under progressive soil drying and rewetting, using a treatment mimicking field *** a preliminary study with eight soybean genotypes, two drought-tolerant genotypes and one susceptible genotype were grown in the greenhouse and subjected to water restriction. Leaf expansion rate, gas exchange, water relation parameters, total chlorophyll(Chl), proline contents of leaves, and root xylem p H were monitored in a time course, and plant growth and root traits were measured at the end of the stress cycle. Drought-tolerant genotypes maintained higher leaf expansion rate, net photosynthetic rate(Pn), Chl content,instantaneous water use efficiency(WUEi), % relative water content(RWC), water potential(ψw), and turgor potential(ψp) during progressive soil drying and subsequent rewetting than the susceptible genotypes. By contrast, stomatal conductance(gs) and transpiration rate(Tr)of tolerant genotypes declined faster owing to dehydration and recovered more sharply after rehydration than the same parameters in susceptible ones. Water stress caused a significant increase in leaf proline level and root xylem sap p H of both genotypes but tolerant genotypes recovered to pre-stress levels more quickly after rehydration. Tolerant genotypes also produced longer roots with higher dry mass than susceptible genotypes. We conclude that rapid perception and adjustment in response to soil drying and rewetting as well as the maintenance of relatively high Pn, %RWC, and root growth constitute the mechanisms by which drought-tolerant soybean genotypes cope with water stress.

关键词： Drought tolerance Water restriction Photosynthesis Root growth Xylem sap pH Soybean genotypes

Cycling performance of layered oxide cathode materials for sodium-ion batteries

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1720-1744页

作者： Jinpin Wu Junhang Tian xueyi Sun Weidong Zhuang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory for Green Recovery and Extraction of Rare and Precious Metals University of Science and Technology BeijingBeijing 100083China

Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple *** performance is an important criterion for evaluating the application prospects of ***,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application ***,this review proposes several strategies to address these ***,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion ***,homogeneous surface coating and concentration gradient modification are *** addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are ***,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.

关键词： sodium-ion battery layered oxide materials cycling performance bulking doping surface coating concentration gradient mixed structure high-entropy