检索结果-南通市图书馆

Al−Si−Fe−Mn合金熔体保温过程中富铁相的三维形态特征和生长行为

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2024年第6期34卷 1745-1758页

作者：宋东福赵愈亮贾义旺李新涛周楠郑开宏张卫文广东省科学院新材料研究所广东省金属强韧化技术与应用重点实验室广州510650 华南理工大学金属材料近净成形国家工程技术研究中心广州510641 东莞理工大学机械工程学院东莞523808 贵州大学材料与冶金学院贵阳550025 江西寰球新材料科技有限公司上饶334499

采用扫描电子显微镜、透射电子显微镜、热力学计算和同步辐射X射线成像技术研究Al−7.0Si−1.0Fe−1.2Mn合金熔体保温过程中富铁相的形态演变和生长行为。结果表明,随着保温温度的降低,富铁相的形态由粗大的星形和多边形状转变成细小的汉... 详细信息

采用扫描电子显微镜、透射电子显微镜、热力学计算和同步辐射X射线成像技术研究Al−7.0Si−1.0Fe−1.2Mn合金熔体保温过程中富铁相的形态演变和生长行为。结果表明,随着保温温度的降低,富铁相的形态由粗大的星形和多边形状转变成细小的汉字状以及汉字和多边形的耦合结构。富铁相的三维形貌显示,星形富铁相由多个多分支的初生相和衍生的不规则次生相组成;耦合结构由多面体和枝晶组成;单一汉字相则由枝晶组成。随着保温温度的降低,富铁相的数量、体积分数以及最大富铁相的体积和连通性显著降低。原位同步辐射X射线结果显示,在凝固过程中形成了两类初生富铁相,其中尺寸较小的初生富铁相保留在熔体中,并成为耦合共晶结构富铁相的形核质点。

关键词：保温温度 Al−Si合金富铁相 3D形态演变同步辐射X射线

Development of S-Band High Power Klystron

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2020年第4期29卷 772-778页

作者： WANG Shengchang DONG Dong PEI Shilun ZHOU Zusheng FUKUDA Shigeki zheng kai Institute of High Energy Physics Chinese Academy of Sciences High Energy Accelerator Research Organization Hubei Hanguang Technology Co. Ltd

A 2998 MHz, 60 MW klystron has been developed for future linear accelerators of synchrotron radiation *** order to save development and construction time, the 2998 MHz, 60 MW klystron is a modified version of an existing 2856 MHz klystron used in linear accelerator of Beijing Electron-Positron Collider Ⅱ.Based on the simulations, it was shown that the scaled version klystron was able to produce more than 60 MW at a 350 kV beam voltage.A prototype was built and *** successfully produced 50 MW output power with an RF pulse width of 4.0μs, which exceeded the operating requirement of China’s High Energy Photon *** also produced 62 MW with an RF pulse width of 1.6μs, which proved the validity of new RF circuit *** paper describes the details of the progresses of this klystron and advantages of this tube development.

关键词： Klystron Linear accelerator Radio-frequency(RF) source

松墨天牛成虫卵巢发育过程及引诱剂诱集雌虫发育状态

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

昆虫学报 2024年第3期67卷 384-392页

作者：朱浩诚顾宇彤郑凯文董奕帆樊建庭浙江农林大学林业与生物技术学院生物农药高效制备技术国家地方联合工程实验室杭州311300

【目的】探究松墨天牛Monochamus alternatus雌成虫卵巢发育过程,从日龄的角度对松墨天牛卵巢发育进行分级,并且判断引诱剂野外诱捕雌成虫的发育状态,为松墨天牛高效防控提供参考。【方法】对达到0, 5, 10, 15, 20, 30, 40和15日龄交配... 详细信息

【目的】探究松墨天牛Monochamus alternatus雌成虫卵巢发育过程,从日龄的角度对松墨天牛卵巢发育进行分级,并且判断引诱剂野外诱捕雌成虫的发育状态,为松墨天牛高效防控提供参考。【方法】对达到0, 5, 10, 15, 20, 30, 40和15日龄交配前后的松墨天牛雌成虫以及引诱剂诱集雌成虫进行生物解剖,观察卵巢发育状态。【结果】松墨天牛雌成虫卵巢发育过程分为5级:发育前期(0-5日龄):卵巢管透明纤细,无卵黄沉积;卵黄沉淀期(5-15日龄):卵巢管内含有少数乳白色和淡黄色未成熟的卵粒;卵巢成熟期(15-20日龄):卵巢管内包含大量完全成熟的卵粒,呈长纺锤形,黄色饱满有光泽;产卵盛期(20-40日龄):输卵管萼中堆满成熟卵粒,中输卵管和侧输卵管中存在待产的卵粒;衰老期(≥40日龄):卵巢管、输卵管萼和输卵管逐渐萎缩。交配后的雌成虫能够产生受精卵,输卵管萼膨大、形态清晰;未交配的雌成虫无法产生受精卵,卵粒堆积在输卵管中无法产出,输卵管萼未分化完全、形态不清晰。野外诱集结果显示,诱集的不同日龄的雌成虫量具有显著性差异,其中处于产卵盛期的雌成虫占比最多,占总量的54.90%±5.50%;卵巢成熟期、衰老期和卵黄沉淀期的雌成虫占比较少,分别占总量的31.37%±5.52%, 11.76%±1.54%和1.96%±0.51%;没有诱集到发育前期的雌成虫。【结论】松墨天牛雌成虫发育至15-20日龄达到性成熟;交配行为能够促进松墨天牛雌成虫卵巢发育。引诱剂可以诱捕到大量刚性成熟的松墨天牛成虫,对于减少松墨天牛产卵量,降低下一代发生基数,降低松材线虫Bursaphelenchus xylophilus传播几率具有积极意义。

关键词：松墨天牛卵巢发育日龄引诱剂诱集

New approaching condition for sliding mode control design with Lipschitz switching surface

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2009年第11期52卷 2032-2044页

作者： zheng kai SHEN TieLong YAO Yu Simulation and Control Center Harbin Institute of Technology Harbin 150001 China Department of Engineering and Applied Sciences Sophia University Tokyo 1028554 Japan

In this paper, we concern the approaching condition of sliding mode control （SMC） with a Lipschitz switching surface that may be nonsmooth. New criteria on the relation between phase trajectories and an arbitrary Lipschitz continuous surface are examined firstly. Filippov＇s differential inclusion is adopted to describe the dynamics of trajectories of the closed-loop system with SMC. Compared with Filippov＇s criteria for only smooth surface, new criteria are proposed by utilizing the cone conditions that allow the surface to be nonsmooth. This result also yields a new approaching condition of SMC design. Based on the new approaching condition, we develop the sliding mode controller for a class of nonlinear single-input single-output （SISO） systems, of which the switching surface is designed Lips- chitz continuous for the nonsmooth sliding motion. Finally, we provide a numerical example to verify the new design method.

关键词： sliding mode control Filippov solution contingent cone linear Lipschitz switching surface

Synthesis and antitumor activity of N^1-acetylamino-(5-alkyl/aryl-1,3,4-thiadiazole-2-yl)-5-fluorouracil derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2008年第11期19卷 1281-1284页

作者： kai Bo zheng Jun He Jie Zhang College of Chemistry Sichuan University Chengdu 610064 China Department of Nephrology West China Hospital Sichuan University Chengdu 610041 China

A new series of N^1-acetylamino-（5-alkyl/aryl- 1,3,4-thiadiazole-2-yl）-5-fluorouracil derivatives were designed and synthesized. These compounds have not been reported in literature, and their structure chemical were confirmed by IR, ^1H NMR and MS （HRMS）. The results of antitumor inhibitory activity test showed that some compounds possess more potent antitumor inhibitory activity than 5-fluorouracil.

关键词： 5-Fluorouracil derivatives 1,3,4-Thiadiazole Synthesis Antitumor

在线全文

学校读者我要写书评

暂无评论

聚乙烯管焊接接头相控阵超声检测的优化设计

计算机测量与控制 2024年第3期32卷 50-56页

作者：吴军吴胜平郑凯范正许倩王海涛江苏省特种设备安全监督检验研究院南京210036 南京航空航天大学自动化学院南京210016

在管道工程应用中,由于良好的耐腐蚀性和韧性,聚乙烯(PE)管与其他材料相比具有显着优势,已广泛地应用在核电、油气输送领域;PE管焊接过程中,焊接参数、人员操作和环境等因素会影响聚乙烯管道的焊接情况,可能致使焊接接头内部形成缺陷,... 详细信息

在管道工程应用中,由于良好的耐腐蚀性和韧性,聚乙烯(PE)管与其他材料相比具有显着优势,已广泛地应用在核电、油气输送领域;PE管焊接过程中,焊接参数、人员操作和环境等因素会影响聚乙烯管道的焊接情况,可能致使焊接接头内部形成缺陷,影响管道安全运行,而相控阵超声检测技术能够实现聚乙烯管道焊接接头内部结构的无损检测及评估;因此开展PE管焊接接头的相控阵超声实际检测工作,研究了聚乙烯材料的声衰减规律及声频散效应,优化了焊接接头的超声相控阵检测工艺,基于CIVA仿真软件实现了聚乙烯管道相控阵超声检测的声场模拟和缺陷仿真,通过研究检测参数及声学参量变化对检测结果的影响,获得了PE管焊接接头的最优检测工艺;通过加工带有典型缺陷的聚乙烯热熔对接接头试样,对前期基于仿真结果设计的检测工艺以及针对焊接接头相控阵检测研发的楔形耦合组件进行可靠性测试和工艺试验;研究结果为PE管接头缺陷的超声相控阵检测提供了工艺设计的理论支持和可靠的研究方法。

关键词：聚乙烯管道焊接接头相控阵超声最优检测工艺楔形耦合组件

Effects of Ni content and tempering temperatures on microstructure and properties of medium-carbon cast steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第8期30卷 1524-1536页

作者： Xiao-bo Cui Tian-long Liu Zhi-bin zheng Zhi-qiang Guo kai-hong zheng Pei-xian Han School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870LiaoningChina Institute of New Materials Guangdong Academy of SciencesNational Engineering Research Center of Powder Metallurgy of Titanium and Rare MetalsGuangdong Provincial Key Laboratory of Metal Toughening Technology and ApplicationGuangzhou 510651GuangdongChina Guangdong Provincial Iron Matrix Composite Engineering Research Center Guangzhou 510651GuangdongChina Jiangxi Lianfeng Investment Casting Co. Ltd.Yichun 336300JiangxiChina

The microstructure evolution and properties of medium-carbon cast steel alloyed with different Ni contents after tempering at various temperatures have been *** addition of 0.47-1.59 wt.%Ni content results in the formation of 16%-36% retained austenite(RA).The blocky and irregular-polygonal RA mainly forms along the prior austenite grain boundaries,and the tempering temperature does not affect the RA *** hardness of medium-carbon cast steel is affected by the precipitation of carbides and the hardness of *** RA content is the main cause of intergranular impact rupture and low impact *** long-strip carbides formed after tempering at 320℃ would further reduce the impact energy of medium-carbon cast *** tempering at 220 and 380℃,the increase in impact energy is attributed to the formation of rod-like and spherical carbides and the low-carbon *** the medium-carbon cast steel with high impact energy,its impact-abrasive wear resistance is more ***-cutting and delamination are the primary wear mechanisms.

关键词： Medium-carbon cast steel Ni content Tempering temperature Hardness Impact energy Impact-abrasive wear resistance

Characteristics of mountain glacier surge hazard: learning from a surge event in NE Pamir, China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第7期16卷 1515-1533页

作者： YAO Xin Javed IQBAL LI Ling-jing ZHOU zheng-kai Key Laboratory of Active Tectonic and Crustal Stability Assessment Institute of GeomechanicsChinese Academy of Geological SciencesBeijing100086China Department of Earth Sciences Abbottabad University of Science and TechnologyKPK 22010Pakistan Key Laboratory of Mountain Hazards and Surface Processes Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China

Abnormal glacier movement is likely to result in canyon-type hazards chain,such as the barrier lake of Yarlung Zangbo Grand Canyon formed by glacier debris flow in October 2018 in *** hazard usually evolves from the glacier surge and may occur in a regular *** the characteristics and process of glacier surge is important for early hazard recognition and hazard *** on field investigations,remote sensing interpretations and SAR offset-tracking surveys,this study confirms a typical glacier surge in the northeast Pamir,and presents its characteristics and processes."Black ice"mixed moraines choking uplift and overflowing lateral marine are the most important scenic characteristics,which were formed under the conditions of stagnant glacier downstream and abundant super-glacial *** movement event can be divided into a five-period cycle including quiescent,inoculation,initiation,fracture and *** surge event lasted for about 300 days,initiated in February 2015 developed extensive fracturing zone in spring and early summer at maximum velocity of 10±0.95 m/day,declined after August 2015 and recovered to quiescent status in October 2015 for the next *** average height of glacier"receiving"area increased by 20-40 m with 2.7-3.6×10^8 m^3 ice transferred from glacier"reservoir",and this volume accumulation again require 50-100 years for glacier mass balance which gives approximately 100 years frequency of the glacier ***,long-period increase of precipitation and temperature were favorable for the occurrence,hydrological instability is the direct triggering mechanism,and while the Glacier Lake Outburst Flood(GLOF)hazards are unlikely to occur with this surge.

关键词： Glacier surges Moraine Glacier hazards Mountain glacier Glacier monitoring Offset-tracking SAR

HBsAg阳性孕产妇HBV宫内感染危险因素及其与IL-28B基因多态性的关联

在线全文

学校读者我要写书评

暂无评论

中华医院感染学杂志 2024年第9期34卷 1397-1400页

作者：张效民王静郑开呈刁雪晨孟庆华济南市第二妇幼保健院产一科山东济南271100 济南市第二妇幼保健院妇女保健科山东济南271100 济南市第二妇幼保健院检验科山东济南271100 济南市人民医院新生儿科山东济南271100

目的探讨乙型肝炎病毒(HBV)携带孕产妇HBV宫内感染危险因素及其与白细胞介素-28B(IL-28B)基因多态性的关联。方法选择济南市第二妇幼保健院2019年1月-2022年2月收治的620例HBsAg阳性孕产妇为研究对象,其中50例发生HBV宫内感染患者为感染... 详细信息

目的探讨乙型肝炎病毒(HBV)携带孕产妇HBV宫内感染危险因素及其与白细胞介素-28B(IL-28B)基因多态性的关联。方法选择济南市第二妇幼保健院2019年1月-2022年2月收治的620例HBsAg阳性孕产妇为研究对象,其中50例发生HBV宫内感染患者为感染组,570例未发生HBV宫内感染患者为未感染组,统计两组IL-28B基因rs8099917位点多态性,分析HBV宫内感染危险因素。结果感染组GG基因型及G等位基因频率均高于未感染组(P10^(6)copies/ml、肝脏B超改变及前S1蛋白阳性(P<0.05)。结论HBsAg阳性孕产妇HBV宫内感染与IL-28B基因多态性、HBV DNA水平、肝脏B超改变、前S1蛋白阳性有关。

关键词：孕产妇乙肝表面抗原乙型肝炎病毒白细胞介素28B 宫内感染危险因素