检索结果-南通市图书馆

TC17钛合金激光焊接接头微观组织和力学性能

在线全文

学校读者我要写书评

暂无评论

机械制造文摘（焊接分册） 2024年第2期 1-5页

作者：张群兵东拓谭猛猛门浩翔张建勋西安航空学院西安710077 西安交通大学金属材料强度国家重点实验室西安710049

文中对TC17钛合金进行了激光焊接,对接头的宏观形貌、微观组织、显微硬度和拉伸性能进行了研究。结果表明,TC17母材的微观组织为β相+等轴初生α_(p)相,β相内存在大量次生α_(s)相;热影响区微观组织变化较为复杂,随着离焊缝距离的减小,... 详细信息

文中对TC17钛合金进行了激光焊接,对接头的宏观形貌、微观组织、显微硬度和拉伸性能进行了研究。结果表明,TC17母材的微观组织为β相+等轴初生α_(p)相,β相内存在大量次生α_(s)相;热影响区微观组织变化较为复杂,随着离焊缝距离的减小,α_(p)逐渐减少,β逐渐增多,α_(s)先消失、再产生、然后再次消失;焊缝由β相柱状晶组成,柱状晶内部是细长的枝晶,在焊缝的中下部存在较多气孔;从母材到焊缝,硬度总体呈下降趋势;受α_(s)含量变化的影响,随着离焊缝距离的减小,热影响区显微硬度先降低、再升高、然后再次降低;由于焊缝硬度最低且存在气孔缺陷,接头拉伸断裂在焊缝。

关键词：激光焊微观组织力学性能 TC17钛合金

Numerical prediction of turbidity currents on unsteady sediment-supply

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2013年第3期28卷 396-405页

作者： Ming-yang LIU You-cai tuo Rui-dong AN Jia LI State key Laboratory of Hydraulics and Mountain River Engineering Sichuan University(SKLHMRE) SKLHMRE

A three-dimensional(3D) numerical model of unstable turbidity currents is developed based on the mechanism of sediment transport and turbulence *** this model,numerical simulation of turbidity currents without subsequent supply of muddy water was conducted using the same parameters as were used in the flume *** evolution process of turbidity currents of completely losing supplies observed in the experiment was simulated by the model;validation of the numerical model and the algorithm was *** momentarily interrupted process is regarded as a special case of the gradually interrupted,based on the preceding numerical simulation validity,it is feasible to simulate the motion law of turbidity currents under losing gradually *** this method in this article,the characteristic of sediment-laden flow of losing gradually supplies was obtained,as well as its relationship between front velocity and sediment concentration.

关键词： Turbidity currents Sediment transport Flume experiments Numerical simulation 3D model

Coupled Heat Transfer Simulation of the Spiral Water Wall in a Double Reheat Ultra-supercritical Boiler

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2018年第6期27卷 592-601页

作者： dong Jiancong ZHOU tuo WU Xiaojiang ZHANG Jian FAN Haojie ZHANG Zhongxiao School of Mechanical Engineering Shanghai Jiao Tong University Institute of Engineering Thermophysics Chinese Academy of Sciences Department of Research and Development Shanghai Boiler Works Co. Ltd.

This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m^2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.

关键词： coupled model heat transfer spiral water wall double reheat ultra-supercritical

病毒蛋白质结构与功能的线上线下混合式教学设计

在线全文

学校读者我要写书评

暂无评论

高校医学教学研究（电子版） 2022年第5期12卷 23-27页

作者：王迎晨董妥高虹商蕾曲章义哈尔滨医科大学公共卫生学院卫生微生物学教研室哈尔滨150086

病毒蛋白质结构属于医学微生物学的教学难点问题。为突破难点,我们以呼吸道病毒的蛋白质结构和变异为核心,将生物信息学中的序列检索、比对、蛋白质结构同源建模,与进化轨迹可视化等知识紧密结合。线上以流感病毒为例讲解每个环节的操... 详细信息

病毒蛋白质结构属于医学微生物学的教学难点问题。为突破难点,我们以呼吸道病毒的蛋白质结构和变异为核心,将生物信息学中的序列检索、比对、蛋白质结构同源建模,与进化轨迹可视化等知识紧密结合。线上以流感病毒为例讲解每个环节的操作流程,学生根据指导书对腺病毒和新冠肺炎病毒进行分析。线下讨论课形式由学生汇报分析结果,该教学设计在实践中取得了良好的效果和反馈,是新冠疫情背景下线上线下进行教学的有益探索。

关键词：病毒学结构生物学虚拟仿真实验混合式教学

Multi-domain equivalent method for prediction of elastic modulus of complex fractured rock mass

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2023年第3期20卷 859-872页

作者： JIAO Feng-yu WANG Hui-dong LI tuo CHEN Yun MA Guo-wei School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China Tianjin Key Laboratory of Prefabricated Building and Intelligent Construction Hebei University of TechnologyTianjin 300401China

Reliable estimation of deformation and failure behaviors of fractured rock mass is important for practical engineering *** study proposes a multi-domain equivalent method for fracture network to estimate the deformation properties of complex fractured rock *** comprehends both the advantages of the discrete fracture network model and the equivalent continuum model to capture the features of discontinuities explicitly while reducing computational *** complex fracture network is stochastically split into a number of subfracture networks according to the domain,length or *** analytical solution is derived to infer theoretically the relationship between the elastic moduli of the original complex fractured rock mass and the split subfractured rock masses by introducing a correction term based on the deformation superposition *** simulations are conducted to determine the elastic moduli of split subfractured rock masses using universal distinct element code(UDEC),while the elastic modulus of the original model is estimated based on the currently proposed analytical *** results show that the estimation accuracy with the current domainbased splitting model is far superior compared to those with the other two splitting ***,the estimation method of elastic modulus of complex fractured rock mass based on domain splitting mode of fracture network is identified as the multi-domain equivalent method proposed in this *** reliability of this method is evaluated,and its high computational efficiency is demonstrated through exemplification with regard to different geometric configurations for stochastically artificial discrete fracture *** proposed multi-domain equivalent method constructs the theoretical framework except for the regression analysis hypothesis compared to the density-reduced model equivalent method.

关键词： Fractured rock masses Discrete fracture network Rock mass deformability Multi-domain equivalent method

新冠病毒变异株奥密克戎的变异特点及对免疫学特性的影响

在线全文

学校读者我要写书评

暂无评论

国际免疫学杂志 2022年第1期45卷 1-4页

作者：李宇张哲杜溪乔王迎晨董妥曲章义哈尔滨医科大学公共卫生学院卫生微生物学教研室哈尔滨医科大学中俄医学研究中心环境相关疾病研究所自然疫源性疾病研究室哈尔滨150081

严重急性呼吸综合征冠状病毒2(severe acute respiratory syndrome-coronavirus 2,SARS-CoV-2)新变异株奥密克戎(Omicron)的出现加剧了新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)疫情的传播。奥密克戎变异株首先在非洲发现,Pango lineage进化分类系统将该变异株划分为B.1.1.529变异株,世界卫生组织(World Health Organization,WHO)将该变异株确定为"关切病毒株",命名为Omicron变异株。与以前的"关切病毒株"相比,奥密克戎变异株突变位点多,传播速度快,在感染性和免疫学特性上都有很大的变化,存在着免疫逃逸和突破现有疫苗免疫保护作用的风险。在被发现以来的一个多月时间内,该变异株已在全球77个国家和地区迅速传播,引起了全球的广泛关注。文章就奥密克戎变异株发现过程、流行现状、变异特点、免疫逃逸及防控策略等进行概述。

关键词：严重急性呼吸综合征冠状病毒2 奥密克戎免疫逃逸疫苗

基于虚拟时间反转法的便携集成式超声导波检测系统软件开发

在线全文

学校读者我要写书评

暂无评论

测控技术 2015年第11期34卷 110-113,126页

作者：刘增华董拓灿张易农何存富吴斌北京工业大学机械工程与应用电子技术学院北京100124 北京市计量检测科学研究院北京100029

时间反转法是无损检测领域中十分常用的信号操作方法之一。该方法能够实现信号在缺陷位置处的自适应聚焦,使缺陷波包幅值增强,波形便于识别。以虚拟时间反转代替传统时间反转,在实现传统时间反转功能的前提下,减少检测系统中仪器的使用... 详细信息

时间反转法是无损检测领域中十分常用的信号操作方法之一。该方法能够实现信号在缺陷位置处的自适应聚焦,使缺陷波包幅值增强,波形便于识别。以虚拟时间反转代替传统时间反转,在实现传统时间反转功能的前提下,减少检测系统中仪器的使用并降低其操作难度。以LabVIEW为平台编写软件,采用事件驱动的状态机来架构软件,外接硬件设备搭建的基于虚拟时间反转法的便携集成式超声导波检测平台,能够实现软件对于仪器的精确控制,实现信号的激励和接收、时间反转运算、信号重构以及DI值计算。在3 mm厚的铝板上进行了基于时间反转法的缺陷检测实验,验证了本软件的可行性。

关键词：无损检测时间反转 LabVIEW 仪器控制软件开发

在线全文

学校读者我要写书评

暂无评论

碳纤维复合材料板的声发射源定位

无损检测 2016年第10期38卷 48-52页

作者：刘增华董拓灿彭秋玲何存富吴斌北京工业大学机械工程与应用电子技术学院北京100124

与常规的无损检测技术相比,声发射技术对动态缺陷更为敏感,但在实际应用中,声发射技术却存在板结构中声发射源的定位精度不高、复合材料的各向异性等特性会对声发射信号造成干扰和影响等问题。以声发射技术在实际应用中存在的一些问题... 详细信息

与常规的无损检测技术相比,声发射技术对动态缺陷更为敏感,但在实际应用中,声发射技术却存在板结构中声发射源的定位精度不高、复合材料的各向异性等特性会对声发射信号造成干扰和影响等问题。以声发射技术在实际应用中存在的一些问题为出发点,以各向异性复合材料板为试验对象,探究复合材料结构中的声发射源定位原理,分析了复合材料板中声发射信号的传播特性,绘制了复合材料板中声发射信号传播速度的全向性曲线,最后通过布置传感器阵列实现了复合材料板中的声发射源定位。

关键词：无损检测声发射源定位复合材料板全向性

Effect of Nd content on microstructure and mechanical properties of as-cast Mg-12Li-3Al alloy

在线全文

学校读者我要写书评

暂无评论

China Foundry 2017年第4期14卷 279-285页

作者： Tian-shun dong Xiao-dong Zheng tuo Wang Jin-hai Lliu Guo-lu Li School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132China

In order to improve the mechanical properties of Mg-Li alloy with single β phase structure, Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) alloy was prepared. Subsequently, the as-cast microstructure and mechanical properties were observed and tested. The results showed that the structure of Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) as-cast alloy was composed of β phase matrix and Al_2Nd, Al_(11)Nd_3, MgLiAl_2, Al_4Li_9 and AlLi phases. With the increase of Nd content in the alloy, the Al-Nd intermetallic compounds have a trend to change from needle-like Al_(11)Nd_3 to granular Al_2Nd. The hardness of as-cast Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) alloy was stable at room temperature. The tensile strength of Mg-12Li-3Al-1.1Nd was as high as 180 MPa, the elongation rate of Mg-12Li-3Al-0.7Nd reached 53.7%, and the comprehensive mechanical properties of Mg-12Li-3Al-2.0Nd was the best. PLC phenomenon occurred during the tensile process of the alloys at room temperature. Therefore, the β-based Mg-Li alloy with good plasticity as well as enhanced strength can be obtained by a moderate addition of Nd and Al.

关键词： Mg-Li β Nd microstructure mechanical properties