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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 181-195页

作者： Sheng Cao Hongyu Liu Jin Jiang Ke He Binghua Lv Hao Zhang Lujie Zhang Jingrong Meng Hao Deng xiaodong niu Department of Mechanical Engineering College of EngineeringShantou UniversityShantou515063China China State Shipbuilding Co. Ltd.Huangpu Wenchong Shipbuilding Company Ltd.Guangzhou510715China Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing100080China Shantou Ruixiang Mould Co. Ltd.Shantou515041China Military Representative Office X of Unit 93147 Deyang618000China China National Erzhong Group Co. Deyang Wanhang Die Forging Co.Ltd.Deyang618013China

This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA ***,austenite was almost disappeared,and oxide particle grew significantly after the STA *** a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA *** the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu ***,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.

关键词： 15-5 PH stainless steel Laser powder bed fusion Heat treatment Gradient microstructures Tensile properties

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13N超高纯锗单晶的制备与性能研究

人工晶体学报 2024年第3期53卷 497-502页

作者：顾小英赵青松牛晓东狄聚青张家瑛肖溢罗恺安徽光智科技有限公司滁州239000 广东先导稀材股份有限公司清远511517

13N超高纯锗单晶是制作超高纯锗探测器的核心材料。本文通过还原法获得还原锗锭,再由水平区熔法提纯获得12N高纯锗多晶,最后由直拉法生长得到13N超高纯锗单晶。通过低温霍尔测试、位错密度检测、深能级瞬态谱(DLTS)测试对13N超高纯锗单... 详细信息

13N超高纯锗单晶是制作超高纯锗探测器的核心材料。本文通过还原法获得还原锗锭,再由水平区熔法提纯获得12N高纯锗多晶,最后由直拉法生长得到13N超高纯锗单晶。通过低温霍尔测试、位错密度检测、深能级瞬态谱(DLTS)测试对13N超高纯锗单晶性能进行分析。低温霍尔测试结果显示,晶体头部截面平均迁移率为4.515×10^(4)cm^(2)·V^(-1)·s^(-1),载流子浓度为1.176×10^(10)cm^(-3),导电类型为p型,位错密度为2256 cm^(-2);尾部截面平均迁移率为4.620×10^(4)cm^(2)·V^(-1)·s^(-1),载流子浓度为1.007×10^(10)cm^(-3),导电类型为p型,位错密度为2589 cm^(-2)。晶体深能级杂质浓度为1.843×10^(9)cm^(-3)。以上结果表明该晶体是13N超高纯锗单晶。

关键词：锗单晶探测器迁移率载流子浓度位错密度

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深海水下技术装备发展研究

中国工程科学 2024年第2期26卷 1-14页

作者：陈旭光寇海磊牛小东王传荣张林强李华军中国海洋大学工程学院山东青岛266100 中国舰船研究院北京100101

深海水下技术装备是认知深海、开发深海资源以及保护海洋生态的关键,拓展深海新空间面临复杂多变的环境挑战,亟需高水平的深海水下技术装备作支撑。本文立足我国海洋强国建设的发展实际,分析了深海水下技术装备的体系构成和发展需求,从... 详细信息

深海水下技术装备是认知深海、开发深海资源以及保护海洋生态的关键,拓展深海新空间面临复杂多变的环境挑战,亟需高水平的深海水下技术装备作支撑。本文立足我国海洋强国建设的发展实际,分析了深海水下技术装备的体系构成和发展需求,从深海观测/探测与感知系统、水下施工作业装备、深海水下油气生产系统、深海矿产资源开发装备4个方面出发,梳理了国外深海水下技术装备的发展现状和趋势。在此基础上,总结了我国深海水下技术装备研制的发展现状,分析了发展面临的工程挑战,剖析了相关关键技术装备体系和关键物理–力学机制,概括了深海水下技术装备的典型装备代表和装备图谱,凝练了我国深海水下技术装备的共性关键技术,涵盖智能化与自动化技术、精密元器件加工制造技术、高精度定位导航、高速率通信技术、大系统力学计算与分析和跨尺度工程设计方法与技术等方面。为实现我国深海水下技术装备的高质量发展,研究建议:加强深海水下工程技术发展的顶层设计,推动构建共性关键技术协作体系;增强我国深海水下技术规范和标准的行业影响力,大力开拓国际市场;高质量推进兼容通用的平台建设;注重培养深海水下工程科技创新人才,为加速实现海洋科技产业高水平发展提供支撑。

关键词：深海装备关键技术观测/探测与感知水下施工油气生产深海采矿

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热带常绿阔叶林冠层光合作用光响应特征

陆地生态系统与保护学报 2024年第2期4卷 24-31页

作者：牛晓栋庞勇徐海龙余涛中国林业科学研究院资源信息研究所北京100091 国家林业和草原局林业遥感与信息技术重点实验室北京100091 云南大学国际河流与生态安全研究院昆明650500

【目的】研究云南省典型热带常绿阔叶林的冠层光合作用光响应特征,为理解森林碳汇时空变化特征提供科学依据。【方法】基于云南省景洪市普文热带常绿阔叶林通量塔从2023年3月至2024年2月的观测数据,利用Michaelis-Menten方程,以1个月为... 详细信息

【目的】研究云南省典型热带常绿阔叶林的冠层光合作用光响应特征,为理解森林碳汇时空变化特征提供科学依据。【方法】基于云南省景洪市普文热带常绿阔叶林通量塔从2023年3月至2024年2月的观测数据,利用Michaelis-Menten方程,以1个月为时间窗口,拟合生态系统光合作用的3个光响应特征参数(以下简称“光合参数”),并与相应时间尺度的环境因子平均值进行相关分析。【结果】热带常绿阔叶林的表观初始光能利用效率(apparent initial light use efficiency,ɑ)和生态系统暗呼吸速率(dark ecosystem respiration,R_(d))有相似的季节变异特征,均在10月份达到最大值,2月份为最小值;最大光合速率(maximum photosynthesis rate,P_(max))在3至5月较低,其余月份变化不明显。与ɑ、R_(d)和P_(max)的季节变异相关性最大的环境因子分别是风速、空气相对湿度和饱和水汽压差,冠层导度也对Rd和Pmax的季节变异有一定影响。【结论】热带常绿阔叶林的3个冠层光合参数有明显的季节变异特征,风速和水分条件相比光合有效辐射和空气温度对光合参数的季节变异有更大影响。

关键词：天然林光合参数涡度相关饱和水汽压差云南

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基于心率变异性的阵发性心房颤动预测方法

中国医学物理学杂志 2024年第5期41卷 579-587页

作者：牛晓东柴国强王大为卢莉蓉韩玲娜连亚军长治医学院生物医学工程系山西长治046000 长治医学院山西省智能数据辅助诊疗工程研究中心山西长治046000 山西师范大学物理与信息工程学院山西太原030000 长治医学院生理学教研室山西长治046000 长治医学院附属和平医院全科医疗科山西长治046000

基于心率变异性(HRV)的特征分析,提出一种患者阵发性房颤(PAF)发作的预测系统方法。首先,基于一种新的自适应滤波技术逐次平滑滤波并粗粒化HRV后,采用熵量化HRV在多个自适应尺度的复杂性特征;其次,特征经MinMax归一化和序列前向选择特... 详细信息

基于心率变异性(HRV)的特征分析,提出一种患者阵发性房颤(PAF)发作的预测系统方法。首先,基于一种新的自适应滤波技术逐次平滑滤波并粗粒化HRV后,采用熵量化HRV在多个自适应尺度的复杂性特征;其次,特征经MinMax归一化和序列前向选择特征子集,输入支持向量机识别HRV类型,预测PAF发作。经50例时长5 min HRV序列集的五折交叉验证,得到最优预测结果为:准确率98%,敏感性100%,特异性96%,性能表现优越。另外,实验表明远离和紧随PAF时的HRV复杂性特征值在不同频率段内,分别具有不同的显著变化(P<0.05),反映受试者神经系统调节心脏节律改变,以及调控机体、应激等适应外界环境变化能力的下降。

关键词：阵发性房颤心率变异性熵尺度积分均值模式分解

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Blockchain-Based Certificateless Bidirectional Authenticated Searchable Encryption Scheme in Cloud Email System

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3287-3310页

作者： Yanzhong Sun Xiaoni Du Shufen niu xiaodong Yang College of Mathematics and Statistics Northwest Normal UniversityLanzhou730070China College of Computer Science and Engineering Northwest Normal UniversityLanzhou730070China

Traditional email systems can only achieve one-way communication,which means only the receiver is allowed to search for emails on the email *** this paper,we propose a blockchain-based certificateless bidirectional authenticated searchable encryption model for a cloud email system named certificateless authenticated bidirectional searchable encryption(CL-BSE)by combining the storage function of cloud server with the communication function of email *** the new model,not only can the data receiver search for the relevant content by generating its own trapdoor,but the data owner also can retrieve the content in the same ***,there are dual authentication functions in our ***,during encryption,the data owner uses the private key to authenticate their identity,ensuring that only legal owner can generate the keyword ***,the blockchain verifies the data owner’s identity by the received ciphertext,allowing only authorized members to store their data in the server and avoiding unnecessary storage space *** obtain a formal definition of CL-BSE and formulate a specific scheme from the new system *** the security of the scheme is analyzed based on the formalized security *** results demonstrate that the scheme achieves multikeyword ciphertext indistinguishability andmulti-keyword trapdoor privacy against any adversary *** addition,performance evaluation shows that the new scheme has higher computational and communication efficiency by comparing it with some existing ones.

关键词： Cloud email system authenticated searchable encryption blockchain-based designated server test multi-trapdoor privacy multi-ciphertext indistinguishability

Natural Convection of Temperature-Sensitive Magnetic Fluids in Porous Media

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Advances in Applied Mathematics and Mechanics 2011年第1期3卷 121-130页

作者： Valentin Roussellet xiaodong niu Hiroshi Yamaguchi Frederic Magoules Applied Mathematics and Systems Laboratory Ecole Centrale Paris92295 Chatenay-MalabryFrance Department of Mechanical Engineering Doshisha UniversityKyoto 610-0321Japan

In this article,natural convection of a temperature-sensitive magnetic fluid in a porous media is studied numerically by using lattice Boltzmann *** show that the heat transfer decreases when the ball numbers *** the magnetic field is increased,the heat transfer is enhanced;however the average wall Nusselt number increases at small ball numbers but decreases at large ball numbers due to the induced flow being more likely confined near the bottom walls with a high number of obstacles.

关键词： Temperature sensitive magnetic fluid natural convection porous media lattice Boltzmann method

Liposomes as versatile agents for the management of traumatic and nontraumatic central nervous system disorders:drug stability,targeting efficiency,and safety

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Neural Regeneration Research 2025年第7期20卷 1883-1899页

作者： Mingyu Zhang Chunyu Xiang Renrui niu xiaodong He Wenqi Luo Wanguo Liu Rui Gu Department of Orthopedic Surgery China-Japan Union Hospital of Jilin UniversityChangchunJilin ProvinceChina

Various nanoparticle-based drug delivery systems for the treatment of neurological disorders have been widely ***,their inability to cross the blood–brain barrier hampers the clinical translation of these therapeutic *** are nanoparticles composed of lipid bilayers,which can effectively encapsulate drugs and improve drug delivery across the blood–brain barrier and into brain tissue through their targeting and ***,they can potentially treat traumatic and nontraumatic central nervous system *** this review,we outlined the common properties and preparation methods of liposomes,including thin-film hydration,reverse-phase evaporation,solvent injection techniques,detergent removal methods,and microfluidics ***,we comprehensively discussed the current applications of liposomes in central nervous system diseases,such as Alzheimer's disease,Parkinson's disease,Huntington's disease,amyotrophic lateral sclerosis,traumatic brain injury,spinal cord injury,and brain *** studies related to liposomes are still in the laboratory stage and have not yet entered clinical ***,their application as drug delivery systems in clinical practice faces challenges such as drug stability,targeting efficiency,and ***,we proposed development strategies related to liposomes to further promote their development in neurological disease research.

关键词： Alzheimer's disease amyotrophic lateral sclerosis brain tumors central nervous system Huntington's disease liposome drug delivery neurological disorders Parkinson's disease spinal cord injury traumatic brain injury

Review of materials used in laser-aided additive manufacturing processes to produce metallic products

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Frontiers of Mechanical Engineering 2019年第3期14卷 282-298页

作者： xiaodong niu Surinder SINGH Akhil GARG Harpreet SINGH Biranchi PANDA Xiongbin PENG Qiujuan ZHANG Intelligent Manufacturing Key Laboratory of Ministry of Education Shantou University Shantou 515063 China Shantou Ruixiang Mould Co. Ltd. Jinping S&T Park Shantou 515064 China Department of Mechanical Engineering Indian Institute of Technology Ropar Rupnagar 140001 India IDMEC Institute Superior Tecnico Universidade de Lisboa 1649-004 Lisboa Portugal

Rapid prototyping (RP) or layered manufacturing (LM) technologies have been extensively used to manufacture prototypes composed mainly of plastics, polymers, paper, and wax due to the short product development time and low costs of these technologies. However, such technologies, with the exception of selective laser melting and sintering, are not used to fabricate metallic products because of the resulting poor life, short cycle, poor surface finish, and low structural integrity of the fabricated parts. The properties endowed by these parts do not match those of functional parts. Therefore, extensive research has been conducted to develop new additive manufacturing (AM) technologies by extending existing RP technologies. Several AM technologies have been developed for the fabrication of metallic objects. These technologies utilize materials, such as Ni-, A1-, and Ti-based alloys and stainless steel powders, to fabricate high-quality functional components. The present work reviews the type of materials used in laserbased AM processes for the manufacture of metallic products. The advantages and disadvantages of processes and different materials are summarized, and future research directions are discussed in the final section. This review can help experts select the ideal type of process or technology for the manufacturing of elements composed of a given alloy or material (Ni, Ti, Al, Pb, and stainless steel).

关键词： direct metal deposition laser-based manufacturing rapid manufacturing selective laser meltiiTg additive manufacturing

Study of Forced Convection Heat Transfer of Supercritical CO_(2) in a Horizontal Channel by Lattice Boltzmann Method

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Advances in Applied Mathematics and Mechanics 2010年第5期2卷 564-572页

作者： xiaodong niu Hiroshi Yamaguchi Yuhiro Iwamoto Xinrong Zhang Mingjun Li Yuhiro Iwamoto Department of Mechanical Engineering Doshisha UniversityKyo-Tanabe-ShiKyoto 610-0321Japan Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871P.R.China Department of Mechanical Engineering Xiangtan UniversityHunan 411105P.R.China

The problem of forced convection heat transfer of supercritical CO_(2) in a horizontal channel is investigated numerically by a lattice Boltzmann *** study is stimulated by our recent experimental findings on solar collectors using supercritical CO_(2) as a working fluid,which can achieve the collector efficiency high up to 70%.To deeply understand the heat transfer characteristics of supercritical CO_(2) and provide a theoretical guidance for improving our current experimental system,in present study several typical experimental flow conditions are *** particular,the work focuses on the convective heat transfer characteristics of supercritical CO_(2) flowing in a horizontal channel with mediate Reynolds numbers ranging from 210 to 840 and constant heat fluxes from 400.0 to 800.0 W/m^(2).The simulations show that the heat transfer increases with heat flux and decreases with Reynolds ***,the mechanisms of heat transfer enhancement of supercritical CO_(2) fluid are identified.

关键词： Forced convection supercritical CO_(2) lattice Boltzmann method