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Effect of nitrogen on microstructure and secondary hardening of H21 die steel

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Journal of Iron and Steel Research International 2019年第5期26卷 483-489页

作者： jin-bo Gu Hua-qing liu jing-yuan Li Yan-bin Jiang Rui-jin Chang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Key Laboratory for Advanced Materials Processing of Ministry of Education University of Science and Technology Beijing Beijing 100083 China

The effect of nitrogen on the microstructure and secondary hardening of H21 die steel was studied by using scanning electron microscope, X-ray diffraction, transmission electron microscope and dilatometer. The results demonstrate that nitrogen can enhance the secondary hardening behavior of H21 hot-working die steel without toughness lose. Nitrogen addition increases the austenitic phase zone, decreasing austenite transformation temperature and martensite transformation temperature, thereby increasing the retained austenite stability. Retained austenite in quenched steel can dissolve a large quantity of alloy, thereby decreasing the coarsening rate of the precipitates. Trace nitrogen could intensify the refinement of pearlite by decreasing the diffusion rate of alloying element into carbides. Nitrogen increases the amounts and precipitation temperature of the undissolved V(C, N) and suppresses the growth of prior austenite before quenching. During tempering process, parts of nitrogen in V(C, N) dissolved back into the matrix, resulting in the distorting lattice of ferrite, thereby reinforcing the matrix. Meanwhile, the solid-dissolved nitrogen inhibits the growth of carbides by decreasing the diffusion rate of alloying elements.

关键词： Nitrogen Secondary hardening H21 die steel Precipitate

长粒香型优质常规稻新品种松雅77的选育与应用

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中国稻米 2024年第5期30卷 123-125页

作者：潘孝武闵军盛新年李小湘刘利成刘文强董铮郭梁陈祖武胡敏湖南省水稻研究所/农业农村部长江中下游籼稻遗传育种重点实验室长沙410125

松雅77是湖南省水稻研究所以玉针香辐射后代M37为母本、象牙香占为父本杂交,经多代系统选育而成的长粒型香稻品种。该品种具有生育期适宜、株型紧凑、株高适中、米质优良、丰产稳产的特征特性,于2024年通过湖南省农作物品种审定委员会... 详细信息

松雅77是湖南省水稻研究所以玉针香辐射后代M37为母本、象牙香占为父本杂交,经多代系统选育而成的长粒型香稻品种。该品种具有生育期适宜、株型紧凑、株高适中、米质优良、丰产稳产的特征特性,于2024年通过湖南省农作物品种审定委员会审定。本文介绍了松雅77的选育经过、特征特性、重要等位基因及栽培技术要点。

关键词：水稻香稻长粒松雅77

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海洋大气环境下镁合金腐蚀行为研究进展

稀有金属材料与工程 2024年第4期53卷 1170-1180页

作者：周慧敏黄须强孔令菲陈建鑫高飞刘绍红陈民芳张晋铁镝东北大学材料科学与工程学院辽宁沈阳110819 天津理工大学材料科学与工程学院天津300384 大连交通大学连续挤压教育部工程研究中心辽宁大连116028

本文综合研究了海洋大气环境下镁合金腐蚀行为的研究进展,比较分析了各种因素对腐蚀行为的影响,对当前研究进展进行总结并对未来研究方向进行展望。在海洋大气环境下,表面薄电解质溶液膜的包覆是镁合金发生电化学腐蚀的主要原因,且多发... 详细信息

本文综合研究了海洋大气环境下镁合金腐蚀行为的研究进展,比较分析了各种因素对腐蚀行为的影响,对当前研究进展进行总结并对未来研究方向进行展望。在海洋大气环境下,表面薄电解质溶液膜的包覆是镁合金发生电化学腐蚀的主要原因,且多发生局部腐蚀。相比于内陆大气环境,海洋大气中含有较多无机盐气溶胶颗粒,导致点蚀成为主要的局部腐蚀形式。相对湿度的升高会导致薄电解质膜厚度增加,进而加速整体腐蚀速率。随气温上升,镁合金的大气腐蚀速率线性增加,而空气中的CO_(2)可以抑制NaCl对镁合金的侵蚀。该领域未来需更多关注具体使役环境下合金的腐蚀机理,以及各种环境因素对腐蚀行为的协同作用机制,以指导海洋用镁合金材料的设计和制备。

关键词：镁合金海洋环境腐蚀大气腐蚀局部腐蚀

Influence on the Solid−Liquid Two-Phase Flow from Cross-Section Area of Slurry Pumps for Deep-Sea Mining

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China Ocean Engineering 2022年第3期36卷 439-450页

作者： WANG Run-kun ZHU Zu-chao SU Xiang-hui TANG Da-sheng jin Xing Maciej GRUSZCZYNSKI The Province Key Lab of Fluid Transmission Technology Zhejiang Sci-Tech UniversityHangzhou 310018China State Key Laboratory of Deep Sea Mineral Resources Development and Utilization Changsha Institute of Mining and MetallurgyChangsha 410000China Wroclaw University of Environmental and Life Sciences Wroclaw 52-124Poland

To explore the mechanism of solid-liquid two-phase flow in deep-sea mining pumps,this paper investigates the influences of the impeller cross-section area on the multi-phase flow in the slurry *** and numerical results are presented for two-phase flow in four impellers with different cross-section *** show that the degree of vortex strength and the passing capacity of particles increase as the cross-section area of the *** addition,the correlations between the two-phase flow and cross-section area have been revealed by a mathematical model taking the force of the flow field into *** simulation results confirm the theoretical analysis,while the experimental pump performances validate the numerical *** influence of the cross-section area on two-phase flow and pump performance could provide theoretical support for the design of high-performance deep-sea mining slurry pumps.

关键词： deep-sea mining slurry pump CFD-DEM solid-liquid two-phase flow Rossby number

A Combined Numerical-Experimental Study on the Noise Power Spectrum Produced by an Electromagnetic Sensor for Slurry Flow

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Fluid Dynamics & Materials Processing 2021年第3期17卷 511-529页

作者： Song Gao Xin jin Qiaohong liu College of Agricultural Equipment Engineering Henan University of Science and TechnologyLuoyang471023China School of Medical Instruments Shanghai University of Medicine and Health SciencesShanghai201318China

The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry *** this study,the power spectrum characteristics of the signal are studied,and an attempt is made to determine the relationship between the characteristics of the related noise and the velocity and concentration of the slurry *** experiments are conducted and the related power spectrum curve is obtained processing the signal measured by the sensor with *** simulations are also carried out in the frame of an Eulerian approach in order get additional insights into the considered problem through comparison with the experimental *** following conclusions are drawn:(1)The intensity of noise is directly proportional to the number of solid particles colliding with the electrode of the electromagnetic flow sensor per unit time,and to the square of the average velocity of the flow layer near the pipe wall.(2)With an increase in the slurry noise intensity,the power spectrum curve shifts upward in the logarithmic coordinate system(and vice versa).

关键词： Electromagnetic flow sensor slurry noise power spectrum kinetic energy theorem

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医学影像学教学模式的现状与实践

中国继续医学教育 2024年第3期16卷 76-79页

作者：刘灿丽郭立郝金钢昆明医科大学第二附属医院放射科云南昆明650101

医学影像学是临床医学中一门实践性极强辅助学科,同时也是发展迅猛,日新月异的学科,在现代医疗中扮演着越来越重要的角色。文章通过对影像医学教学的基本要求、教学目标和目的进行说明,采用影像存储和传输系统(picture archiving and co... 详细信息

医学影像学是临床医学中一门实践性极强辅助学科,同时也是发展迅猛,日新月异的学科,在现代医疗中扮演着越来越重要的角色。文章通过对影像医学教学的基本要求、教学目标和目的进行说明,采用影像存储和传输系统(picture archiving and communication system,PACS)结合以问题为基础的教学法(problem-based learning,PBL)及以案例为基础的教学法(case-based learning,CBL)教学法进行实践。针对非影像专业学员学习时间短、学习任务重,学员影像基础和需求迥异,部分非影像专业学员自身对医学影像学的重视不足以及放射基地重视不足等问题。文章阐述了PACS与PBL、CBL教学法、钉钉、微信及SPARK学习平台等学习沟通平台相结合,并增加专职人员对基地管理、带教老师一对一指导,以及不断加强科室建设、安排名师上课来提高科室影响力等多种混合教学模式的解决对策,来唤起学员学习影像相关知识的内驱力,达到提高学员轮转学习效果的目的。

关键词：医学影像学教学模式以问题为基础的教学法以案例为基础的教学法影像存储与传输系统 SPARK学习平台

Longitudinal impedance measurements and simulations of a three-metal-strip kicker

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Nuclear Science and Techniques 2023年第4期34卷 115-126页

作者： jin-liu Su Yu-Dong liu Sai-Ke Tian Lei Wang Na Wang Sen Yue Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China

A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.

关键词： Ceramic slat kicker Three-metal-strip kicker Impedance bench measurement Coaxial wire method Heat deposition power

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以课程思政改革为引领推进专业人才的培养

教育教学论坛 2024年第3期 185-188页

作者：王妮刘黎红杜金长春职业技术学院食品与生物学院吉林长春130033

长春职业技术学院食品专业群依托课程思政改革,推行总结了“三位一体”德育元素协同的PDCA循环“德技并修”人才培养课程教学模式及课程改革建设经验;通过实施“一体平台、三向协同、拓展互选、双线贯通”专业群课程思政育人体系,全面... 详细信息

长春职业技术学院食品专业群依托课程思政改革,推行总结了“三位一体”德育元素协同的PDCA循环“德技并修”人才培养课程教学模式及课程改革建设经验;通过实施“一体平台、三向协同、拓展互选、双线贯通”专业群课程思政育人体系,全面深化专业群课程思政协同育人改革,针对专业课程思政建设及教学改革实践过程中出现的各类问题,提出了解决措施,取得了良好的成果,提升了学生的综合职业素养,实现了高职学生的德育培养,扭转了重智轻德的现象,对提高人才培养质量具有重要意义。

关键词：课程思政德技并修 “三位一体”德育元素协同 PDCA循环教学模式育人体系

包被纳米氧化锌对断奶仔猪生长性能、免疫功能和肠道屏障的影响

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饲料研究 2024年第2期47卷 16-20页

作者：李慧刘金松刘玉兰张严孔随飞曹广添浙江惠嘉生物科技股份有限公司浙江湖州313300 中国计量大学浙江杭州310018

研究旨在比较不同形式纳米氧化锌对断奶仔猪生长性能、免疫功能和肠道屏障的影响。选取192头24日龄左右、体重(7.47±0.62)kg的断奶仔猪(公、母各半),随机分为4组,每组6个重复,每个重复8头仔猪。对照组饲喂基础饲粮,试验Ⅰ组、试验Ⅱ组... 详细信息

研究旨在比较不同形式纳米氧化锌对断奶仔猪生长性能、免疫功能和肠道屏障的影响。选取192头24日龄左右、体重(7.47±0.62)kg的断奶仔猪(公、母各半),随机分为4组,每组6个重复,每个重复8头仔猪。对照组饲喂基础饲粮,试验Ⅰ组、试验Ⅱ组、试验Ⅲ组分别在基础饲粮中添加2000 mg/kg纳米氧化锌、500 mg/kg包被纳米氧化锌、1000 mg/kg包被纳米氧化锌。试验期14 d。结果显示,纳米氧化锌的总有效率为7.12%,远低于包被纳米氧化锌的78.54%;不同形式纳米氧化锌均可以显著提高断奶仔猪的试验末重和平均日增重(P<0.05),显著降低料重比和腹泻率(P<0.05),试验Ⅲ组效果最佳;与对照组相比,各试验组断奶仔猪血清中免疫球蛋白M和免疫球蛋白A含量显著提高(P<0.05),试验Ⅰ组和试验Ⅲ组断奶仔猪空肠和回肠的分泌型免疫球蛋白水平显著提高(P<0.05);不同形式纳米氧化锌均显著降低了断奶仔猪血清中二胺氧化酶活性和内毒素含量(P<0.05)。研究表明,在饲粮中添加纳米氧化锌和包被纳米氧化锌均可促进断奶仔猪生长,降低腹泻率,增强免疫功能和肠道屏障功能,1000 mg/kg包被纳米氧化锌的作用效果较好。

关键词：包被纳米氧化锌断奶仔猪生长性能免疫功能肠道屏障

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