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Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

Dongbei Daxue Xuebao/Journal of Northeastern University 2024年第4期45卷 499-506页

作者： Yao, Yu-Chao Liu, Zhong-Qiu Rong, Wen-Jie Li, bao-kuan School of Metallurgy Northeastern University Shenyang 110819 China

Feeding a cold steel strip into continuous casting（CC）mold is an effective method to improve the center quality of large round bloom. A liquid-columnar-equiaxed solidification three-phase volume averaged solidification model was developed to explore the effect of feeding strip carbon content on solidification structure and macrosegregation distribution of large CC round bloom in this paper. The results show that the carbon content of feeding steel strip has a significant effect on the growth of equiaxed crystals and columnar crystals. Under the condition of both low and high strip carbon contents，the effect of feeding steel strip on increasing equiaxed grain volume fraction will be reduced. The solute concentration and distribution in the casting bloom can be directly affected by regulating the solute concentration of steel strip. The steel strip with 1. 0 times the carbon content of casting steel（rC=1. 0）has the best improvement effect on the large CC round bloom， with the radial extreme difference of carbon content and macrosegregation index of the bloom being 0. 165 7% and 38. 36%，respectively. © 2024 Northeast University. All rights reserved.

关键词： Continuous casting

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Journal of Iron and Steel Research(International) 2024年第2期31卷 389-400页

作者： Li-ping Pan Ya-wei Li Fang-guan Tan Yi-chen Chen Yang-fan Xu Zhu He bao-kuan Li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina National-Provincial Joint Engineering Research Center of High Temperature Materials and Lining Technology Wuhan University of Science and TechnologyWuhan430081HubeiChina

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining technology.The thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling simulation.Combined with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically analyzed.The results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 m.The thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,respectively.The addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the slits.Consequently,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.

关键词： Purging plug Thermomechanical damage Refractory Design of experiments method Stress

A single-ended wideband reconfigurable receiver front-end for multi-mode multi-standard applications in 0.18μm CMOS

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High Technology Letters 2019年第1期25卷 1-7页

作者：陶健 Fan Xiangning bao kuan Institute of RF&OE-ICs School of Information Science and EngineeringSoutheast University

This paper presents a reconfigurable RF front-end for multi-mode multi-standard(MMMS) applications. The designed RF front-end is fabricated in 0.18 μm RF CMOS technology. The low noise characteristic is achieved by the noise canceling technique while the bandwidth is enhanced by gate inductive peaking technique. Measurement results show that, while the input frequency ranges from 100 MHz to 2.9 GHz, the proposed reconfigurable RF front-end achieves a controllable voltage conversion gain(VCG) from 18 dB to 39 dB. The measured maximum input third intercept point(IIP3) is-4.9 dBm and the minimum noise figure(NF) is 4.6 dB. The consumed current ranges from 16 mA to 26.5 mA from a 1.8 V supply voltage. The chip occupies an area of 1.17 mm^2 including pads.

关键词： reconfigurable multi-mode multi-standard (MMMS) receiver front-end gate inductive peaking noise canceling CMOS

LF精炼过程中通电升温阶段底吹氩方式的优化

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东北大学学报（自然科学版） 2024年第4期45卷 507-513页

作者：王宁秦德越李宝宽赵家七东北大学冶金学院辽宁沈阳110819

在LF(ladle furnace)精炼过程的通电升温阶段多采用双喷嘴等流喷吹的吹氩方式.本文提出一种双喷嘴差流吹氩的底吹方式,以某钢厂135 t钢包为原型设计1∶4非等温水模型实验平台,在总流量相同的情况下进行底吹比例为1∶1,2∶1和3∶1的温度... 详细信息

在LF(ladle furnace)精炼过程的通电升温阶段多采用双喷嘴等流喷吹的吹氩方式.本文提出一种双喷嘴差流吹氩的底吹方式,以某钢厂135 t钢包为原型设计1∶4非等温水模型实验平台,在总流量相同的情况下进行底吹比例为1∶1,2∶1和3∶1的温度均匀化实验,结果表明底吹比例为2∶1时的各监测点无量纲温差最小,均匀化效果最好.建立流动-传热耦合数学模型对实验结果进行验证,结果表明在总流量相等的情况下,底吹比例为1∶1,2∶1和3∶1时流动死区占比分别为14.1%,9.1%和9.8%,温度死区占比分别为6.2%,2.6%和0.3%,2∶1差流底吹方式在活跃流场和促进温度均匀化方面具有优势.

关键词：差流吹氩底吹分布温度均匀化非等温水模型流动死区

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A reconfigurable active-G_m-RC filter formultistandard wireless receivers

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High Technology Letters 2015年第2期21卷 119-126页

作者：樊祥宁 bao kuan Tang Li Liu Junbo Gu Chengjie Institute of RF-&OE-ICs School of Information Science and EngineeringSoutheast University

A 4^(th)-order low-pass filter(LPF) based on active-G_m-RC structure for multi-standard system application is presented in this paper.The performances of LPF are controlled by a 1-bit controlvoltage,and the cut-off frequency,channel selectivity,and linearity of the proposed filter can be reconfigured accordingly.In order to improve the accuracy of the cut-off frequency,a binary-weighted switched-capacitor array is employed as the auto-tuning circuits to calibrate the RC-time constant.Fabricated in TSMC 0.18μm RF CMOS process,the proposed LPF achieves a measured cutoff frequency of 1.95 and 12.3MHz for WCDMA and GPS/Galileo application with a bandwidth deviation less than 4%.The measured 1dB compression points are-3.0dBm and-5.1dBm respectively for different modes.The core circuit of LPF consumes 1mW and 1.6mW for WCDMA and GPS/Galileo respectively.And the proposed LPF occupies an area of 0.78mm^2.

关键词：有源RC滤波器标准体系无线接收机可重构低通滤波器钢筋混凝土结构 WCDMA 通用

2022年北京市城区PM_(2.5)水溶性离子含量及其变化特征

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环境科学 2024年第5期45卷 2537-2547页

作者：陈圆圆崔迪赵泽熙常淼景宽沈秀娥刘保献北京市生态环境监测中心大气颗粒物监测技术北京市重点实验室北京100048

为探究北京市大气细颗粒物(PM_(2.5))水溶性离子含量及其变化特征,有针对性地提出污染防治方案,对2022年全年PM_(2.5)水溶性离子、气态前体物(SO_(2)、NO_(2))和气象因素(温度、RH)进行分析测定.结果表明,北京市城区PM_(2.5)中占比最高... 详细信息

为探究北京市大气细颗粒物(PM_(2.5))水溶性离子含量及其变化特征,有针对性地提出污染防治方案,对2022年全年PM_(2.5)水溶性离子、气态前体物(SO_(2)、NO_(2))和气象因素(温度、RH)进行分析测定.结果表明,北京市城区PM_(2.5)中占比最高的水溶性离子为NO_(3)^(-)、NH_(4)^(+)和SO_(4)^(2-),占PM_(2.5)的52.7%,ρ(PM_(2.5))(33.2μg·m^(−3))和ρ(SNA)(18.9μg·m^(−3))低于历史研究结果,但SNA占比(52.7%)、SOR(0.45)和NOR(0.15)高于历史研究结果,体现出北京市细颗粒物污染得到明显改善,但仍具有较强的二次污染特征.NO_(3)^(-)/SO_(4)^(2-)为2.2,高于历史及附近省市研究结果,反映出移动源的影响不断扩大.从季节变化上看,PM_(2.5)呈现秋高夏低的变化特征,秋、春、冬这3个季节NO_(3)^(-)的占比最高,夏季SO_(4)^(2-)占比最高,而NH_(4)^(+)在各季节占比变化不大.NOR与SOR的季节变化规律几乎相反,反映出二者的转化形成因素存在差异.北京城区SNA的主要存在形式为NH_(4)NO_(3)^(-)和(NH_(4))_(2)SO_(4),其中冬季阴阳离子中和度最高,夏季阳离子NH_(4)^(+)稍显不足,而春秋两季NH_(4)^(+)处于过量状态,北京城区为富氨环境.从污染级别看,水溶性离子质量浓度均随污染加重有不同程度的增长,增长最快的是SNA,其在PM_(2.5)中占比出现先上升后稳定的变化特征.从空间分布特征来看,中心城区和东南西北部郊区的SNA质量浓度大小均为:NO_(3)^(-)>SO_(4)^(2-)>NH_(4)^(+),体现了以NO_(3)^(-)为主导的污染特征;SNA对PM_(2.5)的贡献率最高的区域发生在东部、中心城区和传输点,表明在中心城区和东部地区二次反应相对活跃,同时区域传输也是二次离子的重要来源.

关键词：大气细颗粒物(PM_(2.5)) 水溶性离子二次无机离子(SNA) 质量浓度变化特征

北京城区夏季VOCs初始体积分数特征及来源解析

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环境科学 2024年第1期45卷 81-92页

作者：张博韬景宽王琴安欣欣鹿海峰王陈婧王友峰刘保献北京市生态环境监测中心北京100048 大气颗粒物监测技术北京市重点实验室北京100048

为明确北京市夏季VOCs体积分数特征及来源,在2022年5~8月对北京城区VOCs开展了连续监测并利用光化学比值法计算了初始体积分数.结果表明:①研究期间,北京城区初始φ(TVOCs)为(30.0±11.5)×10^(-9),其中含氧VOCs和烷烃占比达到34.2%和33... 详细信息

为明确北京市夏季VOCs体积分数特征及来源,在2022年5~8月对北京城区VOCs开展了连续监测并利用光化学比值法计算了初始体积分数.结果表明:①研究期间,北京城区初始φ(TVOCs)为(30.0±11.5)×10^(-9),其中含氧VOCs和烷烃占比达到34.2%和33.2%,体积分数较高的物种是丙酮、乙烷、乙醛和丙烷等低碳物质.②北京城区初始TVOCs体积分数略微呈现单峰变化趋势,11:00达到峰值,下午略有降低.③各排放物质中对O3生成贡献较大的主要是异戊二烯、乙醛、正丁醛和乙烯等物质,而对二次有机气溶胶生成贡献较大的主要是甲苯、异戊二烯、间/对-二甲苯和乙苯物质.④基于初始体积分数的PMF解析发现,老化背景及二次源(30%)对北京市VOCs贡献率最高,机动车源(25%)则是最主要的一次人为源,此外溶剂及燃油挥发源贡献率16%,燃烧源贡献率11%,工业过程源贡献率9%,天然源贡献率9%.⑤影响北京市的人为源主要来自东部和南部区域,天然源则来自西部和西北部区域.研究显示,应进一步削减机动车排放,开展区域联防联控降低整个区域VOCs水平是最终控制北京市VOCs的有效手段.

关键词：挥发性有机物(VOCs) 北京初始体积分数来源解析浓度权重轨迹(CWT)

Review on effect of applied internal cooling source and vibration on metal solidification process

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Journal of Iron and Steel Research(International) 2023年第6期30卷 1059-1072页

作者： Yu-chao Yao Miao Liu Zhong-qiu Liu bao-kuan Li Yong Gan Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina China Iron&Steel Research Institute Group Co. Ltd.Beijing 100081China

Advancements in metallurgical technology have led to the emergence of high-performance requirements for metal materials,like high uniformity,high purity,and superfine crystallinity.This has resulted in the development and application of internal cooling source(ICS),vibrational,and vibrational internal cooling source methods in metal solidification processes to afford products with refined crystal grains and large proportions of equiaxed crystals.These methods have gradually been introduced into laboratories and some steel mills over the past few decades.However,there are few successful industrial applications of these methods,as there is no comprehensive understanding of their control theories and principles.Accordingly,the development,basic principles,and classifications of the three types of methods are summarized,and their impact on the solidification of molten metals and the morphology of solid products is discussed.In addition,experimental and numerical simulation-based researches on each type of method are reviewed and their prospects for applications are briefly discussed to control metal solidification.Finally,detailed future perspectives are provided on vibratory strip feeding,ICS,and pulsed magneto-oscillation methods.Hopefully,it will serve as a reference for future studies of the application of these and related methods in metal solidification processes.

关键词： Internal cooling source Vibration Solidification Strip feeding Grain refinement

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不同功能型沉水植物对溶解氧影响及环境效应

水生生物学报 2024年第2期48卷 232-241页

作者：李华歆殷春雨杨国梁蔡颖黄晓龙李宽意关保华中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室南京210008 中国科学院大学北京100049 上海建桥学院有限责任公司上海201306 江苏省环境工程技术有限公司南京210019

研究选用刺苦草(Vallisneria spinulosa)、黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)分别代表底层型、冠层少根型和冠层多根型沉水植物,通过中宇宙实验,探索不同功能型沉水植物在生长过程中水柱和沉积物中溶解氧... 详细信息

研究选用刺苦草(Vallisneria spinulosa)、黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)分别代表底层型、冠层少根型和冠层多根型沉水植物,通过中宇宙实验,探索不同功能型沉水植物在生长过程中水柱和沉积物中溶解氧(DO)浓度及其相关指标的差异。实验结果表明:不同处理组水柱DO浓度存在显著差异,空白组水柱DO浓度显著低于植物处理组,且空白组水柱总氮(TN)和总磷(TP)浓度降低程度最少;黑藻组比叶面积、叶面积指数、净增长生物量、相对生长速率和水柱DO浓度最大,能够有效降低水柱TP和TN浓度;穗花狐尾藻组株高最高,提升水柱DO浓度显著高于刺苦草,水柱TP降低程度最大;刺苦草组比根长、单株总根长和根冠比最大,提升沉积物深度6 cm以内的DO效果最好,沉积物铁含量最高,沉积物总氮(TN)、总碳(TC)含量和间隙水总溶解性磷(TDP)浓度最低。在修复富营养湖泊过程中,可根据水和沉积物缺氧状况,合理配置底层型和冠层型沉水植物,构建释氧能力较强的群落,从沉积物表层到水柱上层均为湖泊提供充足的氧气,从而更加有利于清水态的形成。

关键词：功能型沉水植物溶解氧环境效应植冠根系

输尿管软镜钬激光碎石术后医院感染病原学及危险因素

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中华医院感染学杂志 2024年第2期34卷 231-234页

作者：何耿陈仕款王崇锋覃振昌颜保松陈英李威中国人民解放军联勤保障部队第九二八医院泌尿外科海南海口570011 中国人民解放军联勤保障部队第九二八医院检验科海南海口570011 中国人民解放军联勤保障部队第九二八医院疾病预防控制科海南海口570011

目的探究输尿管软镜钬激光碎石术后医院感染危险因素及病原学特征。方法回顾性分析中国人民解放军联勤保障部队第九二八医院2021年2月—2022年12月收治的479例输尿管软镜钬激光碎石术后患者临床资料,根据术后是否发生医院感染,分为感染... 详细信息

目的探究输尿管软镜钬激光碎石术后医院感染危险因素及病原学特征。方法回顾性分析中国人民解放军联勤保障部队第九二八医院2021年2月—2022年12月收治的479例输尿管软镜钬激光碎石术后患者临床资料,根据术后是否发生医院感染,分为感染组51例和非感染组428例,统计感染病原学特征及感染部位分布;通过多因素Logistic分析输尿管软镜钬激光碎石术后医院感染发生的危险因素。结果479例输尿管软镜钬激光碎石术后医院感染发生51例,发生率为10.65%;51例感染患者检出病原菌59株,包括革兰阴性菌37株(62.71%)、革兰阳性菌17株(28.81%)和真菌5株(8.47%),感染组以泌尿系统感染患者占比最高(56.86%);多因素Logistic分析结果显示,术前合并尿路感染、合并糖尿病、手术时间>60 min、未预防性应用抗菌药物、尿管留置时间>7 d是输尿管软镜钬激光碎石术后医院感染发生的危险因素(OR=2.737、3.111、2.540、2.754、2.735,P<0.05)。结论输尿管软镜钬激光碎石术后医院感染发生率较高,感染部位以泌尿系统为主,病原菌以革兰阴性菌为主;术后医院感染与术前合并尿路感染、糖尿病史、手术时间、预防性应用抗菌药物、尿管留置时间有关,临床可据此采取早期针对性干预措施。

关键词：输尿管软镜钬激光碎石术术后感染病原菌危险因素干预措施