检索结果-南通市图书馆

Development of in situ characterization techniques in molecular beam epitaxy

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 Semiconductors 2024年第3期45卷 9-32页

作者： Chao Shen Wenkang Zhan Manyang Li Zhenyu Sun Jian Tang zhaofeng wu Chi Xu Bo Xu Chao Zhao Zhanguo Wang Laboratory of Solid State Optoelectronics Information Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 101804China School of Physics Science and Technology Xinjiang UniversityUrumqi 830046China School of New Energy and Electronics Yancheng Teachers UniversityYancheng 224002China Key Laboratory of Optoelectronic Materials and Devices Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

关键词： epitaxial growth thin film in situ characterization molecular beam epitaxy(MBE)

Top priority current path between SiC particles during ultra-high temperature flash sintering: Presence of PyC “bridges”

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第2期13卷 255-262页

作者： Le Lu Tianlong Liu zhaofeng Chen Fei Wang Mengmeng Yang Qiong wu Lixia Yang Huanyong Li International Laboratory for Insulation and Energy Efficiency Materials College of Materials Science and TechnologyNanjing University of Aeronautics and AstronauticsNanjing 211106China State Key Laboratory of Solidification Processing School of Materials and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

Flash sintering(FS)is a novel technique for rapidly densifying silicon carbide(SiC)ceramics.This work achieved a rapid sintering of SiC ceramics by the utilization of ultra-high temperature flash sintering within 60 s.Pyrolysis carbon(PyC)“bridges”were constructed between SiC particles through the carbonisation of phenolic resin,providing a large number of current channels.The incubation time of the flash sintering process was significantly reduced,and the sintering difference between the centre and the edge regions of the ceramics was minimized,with an average particle size of the centre region and edge region being 12.31 and 9.02μm,respectively.The results showed that the porosity of the SiC ceramics after the flash sintering was reduced to 14.79% with PyC“bridges”introduced,and the Vickers hardness reached 19.62 GPa.PyC“bridges”gradually evolved from amorphous eddy current carbon to oriented graphite carbon,indicating that the ultra-high temperature environment in which the sample was located during the flash sintering was successfully constructed.Ultra-high temperature flash sintering of SiC is expected to be applied to the local repair of matrix damage in SiC ceramic matrix composites.

关键词： silicon carbide(SiC) flash sintering(FS) pyrolytic carbon(PyC)"bridges" current path instantaneous

A lightweight and high compressive resistance thermal insulation material with dual-network structure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第5期17卷 4279-4287页

作者： Mengmeng Yang zhaofeng Chen Yang Ding wu Qiong Tianlong Liu Manna Li Lixia Yang Sheng Cui School of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites Nanjing Tech UniversityNanjing 211816China

Ceramic fibrous aerogels are highly desirable for thermal management materials due to their high porosity,excellent elasticity,thermal conductivity,and good thermal resistance.However,the fabrication of nanofibrous aerogel with super-elasticity and good shape retention at the same time has remained challenging.To meet the requirements,a novel anisotropy nanofibrous-granular aerogel with a quasi-layered multi-arch-like and hierarchical-cellular structure is designed and prepared by vacuum-filtration-assisted freeze-drying and sintering.The quasi-layered multi-arch and flexible nanofibers endowed the aerogels with excellent mechanical robustness(ultimate stress up to 60 kPa with strain 60%)and super-elasticity with recoverable compression strain up to 60%.The introduced SiO_(2) aerogel nanoparticles and nanofibers are assembled into an arch-like structure and become the connection point of adjacent nanofibers,which endows low thermal conductivity(0.024 mW/(m·K))of composite aerogel.This novel strategy provides a fresh perspective for the preparation of nanofibrous aerogel with robust mechanical in thermal insulation and other fields.

关键词： nanofibrous aerogel dual-network structure thermal insulation nanofibrous-granular composite aerogels strong mechanical

A Comparative Study on the Luminescence of the Cd2＋ and Mn2＋ Coordination Polymers Based on the Same Mixed Ligands

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2016年第7期34卷 703-708页

作者： zhaofeng wu Xiaoying Huang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China University of Chinese Academy of Sciences Beijing 100049 China

Presented here is the solvothermal preparation of two luminescent coordination polymers （L-CPs） based on the same mixed ligands, namely [Cd2（1,4-NDC）2（dppe）] （1） and [Mn3（OH）2（1,4-NDC）2（dppe）（H2O）] （2）（1,4-NDCH2 = 1,4-naphthalene dicarboxylic acid, dppe---- 1,3-di（4-pyridyl）propane）. Both the title compounds feature a neutral three-dimensional （3D） network. Photoluminescence （PL） studies indicated that the compound 1 based on d10 Cd2＋ exhibited dual emissions with tunable intensities that could result in direct white-light emission based on the in- traligand charge transfer （LLCT）; while the compound 2 showed a single band of yellow emission based on the charge transfer between the ligands and the metal ion （LMCT）, due to the partially filled d-orbital of Mn2＋ ion. The temperature-dependent powder X-ray diffraction patterns （PXRD） and PL spectra were further measured to identify their thermal stabilities. This work may provide a certain guiding significance for exploiting L-CPs based on different metal ions.

关键词： coordination polymer photoluminescence study white emitting

Fast counting the cardinality of flows for big traffic over sliding windows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2017年第1期11卷 119-129页

作者： Jingsong SHAN Yinjin FU Guiqiang NI Jianxin LUO zhaofeng wu College of Command Information Systems PLA University of Science and Technology Nanjing 223002 China Huaiyin Institute of Technology Huaian 221002 China

Counting the cardinality of flows for massive high-speed traffic over sliding windows is still a challenging work under time and space constrains, but plays a key role in many network applications, such as traffic management and routing optimization in software defined network. In this pa- per, we propose a novel data structure （called LRU-Sketch） to address the problem. The significant contributions are as follows. 1） The proposed data structure adapts a well-known probabilistic sketch to sliding window model; 2） By using the least-recently used （LRU） replacement policy, we design a highly time-efficient algorithm for timely forgetting stale information, which takes constant （O（1）） time per time slot; 3） Moreover, a further memory-reducing schema is given at a cost of very little loss of accuracy; 4） Comprehensive ex- periments, performed on two real IP trace files, confirm that the proposed schema attains high accuracy and high time efficiency.ferences including IEEE TPDS, ACM ToS, JCST, MIDDLEWARE, CLUSTER, NAS, etc. Currently, his research interests include big data management, cloud storage, and distributed file systems.

关键词： probabilistic data structure sketch streaming data cardinality flow

Construction of a Noncentrosymmetric Luminescent Coordination Polymer from [BaL3] Unit (L = Pyridine-2,6-dicarboxylate Acid) and Li(l) Ion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2019年第2期37卷 131-134页

作者： Ying Song zhaofeng wu Bing Hu Xiaoying Huang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China

Summary of main observation and conclusion This work presents the synthesis, crystal structure and properties of a novel noncentrosymmetric (NCS) coordination polymer (CP), namely,(Me2NH2)3[BaLi(2,6-PyDC)3(H2O)](1)(2,6-PyDC = pyridine-2,6-dicarboxylate acid), which represents the first example of BaLi-CPs with 2,6-PyDC ligand. Single-crystal X-ray structural analysis reveals that the compound features a two-dimensional (2D) layered structure. The simplified structure of each layer belongs to the hcb topology. The second harmonic generation (SHG) response of 1 is about 0.5 times that of KH2PO4 (KDP) marker. What is more, 1 emits bright blue light upon the excitation of 365 nm UV light with the quantum yield (QX Ф) of 1.63%. The successful con struction of this compound convinces the feasibility of constructing NCS CPs via the combi nation of [BaL3] unit and Li(l) ion.

关键词： Noncentrosymmetric Luminescent Coordination Polymer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

电磁防护技术发展综述与展望

强激光与粒子束 2024年第4期36卷 1-13页

作者：毋召锋徐延林刘培国查淞国防科技大学电子科学学院长沙410073

针对复杂电磁对抗环境中电子信息装备面临的强电磁环境威胁以及防护加固需求,对强电磁防护技术的发展现状进行了综述,并提出了强电磁系统级综合防护的发展展望。强电磁防护是为了保证电子信息装备在强电磁环境中免受损伤或损毁的技术手... 详细信息

针对复杂电磁对抗环境中电子信息装备面临的强电磁环境威胁以及防护加固需求,对强电磁防护技术的发展现状进行了综述,并提出了强电磁系统级综合防护的发展展望。强电磁防护是为了保证电子信息装备在强电磁环境中免受损伤或损毁的技术手段,从电磁波的耦合途径分析了当前电磁防护的重点和难点,然后分别以限幅器技术、频率滤波技术、能量选择防护技术三个方面对前门防护技术的发展现状进行了分析总结,最后从新型屏蔽材料和防护器件两个方面对新型电磁防护技术进行了展望,并从前后门一体防护、场路一体防护、多域联合防护三个角度对系统级电磁防护进行了总结,为电子信息装备在复杂电磁环境下的电磁防护加固设计提供了支撑。

关键词：电磁防护强电磁环境限幅器技术能量选择技术频域滤波技术

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于装配式周转箱的甘薯气调贮藏环境仿真

食品与机械 2024年第4期40卷 136-147页

作者：胡汝生刘寅孟照峰张帆吴飞骏中原工学院能源与环境学院河南郑州451191

目的:减少果蔬盛装、运输及贮藏时的不利因素,以循环、绿色理念为前提设计出一种装配折叠式塑料周转箱。方法:将甘薯看作长旋转椭球体,以标准化周转箱盛装甘薯并对气调贮藏库进行建模,通过多孔介质模型、组分输运模型、局部非热平衡模... 详细信息

目的:减少果蔬盛装、运输及贮藏时的不利因素,以循环、绿色理念为前提设计出一种装配折叠式塑料周转箱。方法:将甘薯看作长旋转椭球体,以标准化周转箱盛装甘薯并对气调贮藏库进行建模,通过多孔介质模型、组分输运模型、局部非热平衡模型研究愈伤升温、愈伤后降温,以及贮藏阶段货物区的温度、湿度、速度、O 2体积分数、CO_(2)体积分数分布情况。结果:较佳的愈伤送风温度为40℃,所需时间为5.85 h;较佳的愈伤后降温送风速度为10 m/s,所需时间为8.47 h。送风速度(4.0~6.0 m/s)对O 2、CO_(2)体积分数分布影响不大;当送风速度为4.5 m/s时,贮藏效果较佳,与目标贮藏条件(12℃,90.00%RH)相比,偏差率依次为1.24%,0.48%。甘薯呼吸热的产生使得货物区内部温度达到目标愈伤温度所需的时间较短,达到目标贮藏温度所需的时间较长,相较于导热,对流换热占主导作用,造成贮藏过程中货物区内部温度与外部温度变化存在滞后。增大送风温度、送风速度分别有利于缩短达到目标愈伤、贮藏温度所需的时间,货物区贮藏甘薯的物理性质以及贮藏量决定了后续升温、降温过程。结论:货物区表面速度场与相对湿度场分布关联性较小,温度场与相对湿度场呈负相关且分布状态相似。送风速度可以改变货物区箱体内部的流体流向,送风速度大小以及箱体内流体流向对货物区内部温度分布影响较大。

关键词：甘薯周转箱多孔介质不均匀系数数值模拟贮藏

虹吸排水法处理软土地基的水位与沉降计算模型

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

吉林大学学报（地球科学版） 2024年第1期54卷 208-218页

作者：袁帅王君吴朝峰沈青松舒俊伟孙红月浙江大学海洋学院浙江舟山316021 宁波中交水运设计研究有限公司浙江宁波315042 中国能源建设集团浙江省电力设计院有限公司杭州310012 浙江大学建筑工程学院杭州310058

软土具有渗透性差、承载力低等特性,软土地基的处理一直是岩土工程中的一大难题。利用虹吸免动力排水的特点,可将虹吸排水法应用于软土地基处理中,达到改善土体性质的目的。本文针对虹吸排水法独特的定降深降水模式,先基于离散化的Thei... 详细信息

软土具有渗透性差、承载力低等特性,软土地基的处理一直是岩土工程中的一大难题。利用虹吸免动力排水的特点,可将虹吸排水法应用于软土地基处理中,达到改善土体性质的目的。本文针对虹吸排水法独特的定降深降水模式,先基于离散化的Theis井流模型以及非线性的分层总和法,构建了以孔隙率为核心、渗透系数与压缩模量随固结情况改变的水位与沉降动态计算模型,并与数值模拟结果对比,然后从土体渗透系数、排水板间距以及场地大小3个方面对虹吸排水法处理软土地基的效果进行了分析。结果表明:数值模拟结果验证了计算模型的可靠性,对于浙江沿海不同渗透系数的土体,虹吸排水法均可起到良好的排水固结作用;调整排水板间距可对排水固结时间以及地下水位线起到显著控制作用;排水带来的附加应力随着场地面积的增大向土体深处延伸,对于面积50 m×50 m大小的场地,有效影响深度可达到地表以下27.31 m,远远超出虹吸扬程的极限。在实际的大面积软土地基处理中,虹吸排水法可发挥更好的作用。

关键词：软土虹吸排水地基沉降非稳定流井群干扰