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First Evaluation and Frequency Measurement of the Strontium Optical Lattice Clock at NIM 被引量:13
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作者 林弋戈 王强 +7 位作者 李烨 孟飞 林百科 臧二军 孙震 房芳 李天初 方占军 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第9期17-20,共4页
An optical lattice clock based on 87Sr is built at National Institute of Metrology (NIM) of China. The systematic frequency shifts of the clock are evaluated with a total uncertainty of 2.3×10-16. To measure it... An optical lattice clock based on 87Sr is built at National Institute of Metrology (NIM) of China. The systematic frequency shifts of the clock are evaluated with a total uncertainty of 2.3×10-16. To measure its absolute frequency with respect to NIM's cesium fountain clock NIM5, the frequency of a flywheel H-maser of NIM5 is transferred to the Sr laboratory through a 50-kin-long fiber. reference frequency of this H-maser, is used for the optical this Sr clock is measured to be 429228004229873.7(1.4)Hz. A fiber optical frequency comb, phase-locked to the frequency measurement. The absolute frequency of 展开更多
关键词 AOM First Evaluation and Frequency Measurement of the Strontium Optical Lattice Clock at NIM
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NIM的微波-光学频率基准研究——复现米和秒定义 被引量:2
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作者 李天初 《中国工程科学》 2007年第6期27-31,共5页
报道中国计量科学研究院(NIM)在微波-光学频率计量研究的新进展:用NIM4激光冷却-铯原子喷泉钟复现国际单位制(SI)时间单位秒(s),用飞秒(FS)光学频率梳间接复现长度单位米(m)并标定稳频激光波长实际实施米定义。NIM4铯原子喷泉钟的不确... 报道中国计量科学研究院(NIM)在微波-光学频率计量研究的新进展:用NIM4激光冷却-铯原子喷泉钟复现国际单位制(SI)时间单位秒(s),用飞秒(FS)光学频率梳间接复现长度单位米(m)并标定稳频激光波长实际实施米定义。NIM4铯原子喷泉钟的不确定度达到5×10-15,飞秒(FS)光梳锁定到NIM4钟控制的氢钟后,其频率不确定度为2·2×10-14。在此基础上讨论铯原子喷泉钟、稳频激光、FS光梳的作用、意义和相互关系。最后简要介绍NIM5铯原子喷泉钟的研究进展和2006年起NIM立题研制锶原子存储光钟。 展开更多
关键词 计量 频率基准 稳频激光 铯原子喷泉钟 飞秒光梳
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Improvements and New Evaluation of NIM4 Caesium Fountain Clock at NIM in 2005-2006 被引量:1
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作者 李天初 李明寿 +4 位作者 林平卫 王平 陈伟亮 刘年丰 林戈戈 《Chinese Physics Letters》 SCIE CAS CSCD 2007年第5期1177-1179,共3页
The NIM4 caesium fountain clock has been operating stably and sub-continually since August 2003. We present our improvements on NIM4 in 2005-06 and the most recent evaluation for its frequency shifts with an uncertain... The NIM4 caesium fountain clock has been operating stably and sub-continually since August 2003. We present our improvements on NIM4 in 2005-06 and the most recent evaluation for its frequency shifts with an uncertainty of 5 × 10^-15. A 203-day comparison between NIM4 and GPS time shows an agreement of 2 × 10^-14. Finally the construction of the NIM5 transportable caesium fountain clock is briefly reported. 展开更多
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Progress of the Inertial Mass Measurement Project at NIM
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作者 傅壮 张钟华 +3 位作者 李正坤 赵伟 钱璐帅 李世松 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第8期33-36,共4页
An experiment is proposed to precisely measure the Planck constant. In this experiment, the Planck constant is measured based on the inertial mass measurement rather than the gravitational mass determinations in some ... An experiment is proposed to precisely measure the Planck constant. In this experiment, the Planck constant is measured based on the inertial mass measurement rather than the gravitational mass determinations in some other well-known experiments, e.g., the Kibble balance and counting atoms. We link the mechanical force to a quantum-traceable electrostatic force by a beam balance oscillator. After a 5-year continuous effort, the principle of the proposal is verified by a preliminary measurement with a relative uncertainty of 5.4×10^-5. The proposal has the potential to achieve much higher measurement accuracy with further improvements. 展开更多
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基于LIBS的GdFe合金材料快速检测技术研究 被引量:1
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作者 王东杰 张艾蕊 +2 位作者 李华昌 汤淑芳 王选 《中国无机分析化学》 CAS 北大核心 2024年第2期239-246,共8页
为了明晰LIBS(激光诱导击穿光谱)技术检测稀土合金材料的光谱特点,进一步开发基于LIBS的快速检测方法,推动LIBS技术在稀土领域的应用。利用激光诱导击穿光谱仪对GdFe合金材料激发光谱,结合信号强度及背景噪音,研究确定了最佳设置参数。... 为了明晰LIBS(激光诱导击穿光谱)技术检测稀土合金材料的光谱特点,进一步开发基于LIBS的快速检测方法,推动LIBS技术在稀土领域的应用。利用激光诱导击穿光谱仪对GdFe合金材料激发光谱,结合信号强度及背景噪音,研究确定了最佳设置参数。分别考察激光器和光谱仪的参数设置对光谱的影响,根据激发光谱中相关谱线的变化趋势,探讨GdFe合金材料的LIBS检测方法。实验发现,GdFe合金样品与激光孔(Laser aperture)的距离(Z值)、激光能量和积分时间是影响LIBS光谱信号强度和背景噪音的关键参数。因金属和合金样品表面常覆盖氧化层,考察了脉冲激光的预剥蚀次数对光谱稳定性的影响,研究得出,在双脉冲均为164 mJ激光能量的激发下,预剥蚀1次可保证光谱效果。同时研究了两个激光器同时激发和延迟激发对GdFe合金光谱成因的影响,发现单脉冲激发与双脉冲同时激发所得光谱的信号强度并非两束脉冲单独激发的累加信号。通过光谱分析,确定了Z值0.8 mm、两个激光器的脉冲能量164 mJ、积分时间12μs、脉冲延时时间0μs,GdFe合金材料的光谱效果最佳,可为GdFe合金材料的LIBS检测方法建立提供参考,拓展LIBS技术在稀土领域的应用,为稀土合金产品的快速检测技术发展提供基础研究数据。 展开更多
关键词 LIBS GdFe合金 光谱分析 快速检测
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硫系薄膜材料相变温度光功率测量法研究
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作者 吴国栋 金森林 +3 位作者 付俊杰 李硕 任玲玲 贺建芸 《北京化工大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第2期93-100,共8页
相变温度是衡量相变薄膜材料性能的关键参数,对相变存储器的数据保持力、热稳定性和功耗有着巨大的影响,因此相变温度的准确测量非常重要。目前,国内外测量薄膜材料相变温度的主要方法有变温X射线衍射法和差示扫描量热法,前者测量精度有... 相变温度是衡量相变薄膜材料性能的关键参数,对相变存储器的数据保持力、热稳定性和功耗有着巨大的影响,因此相变温度的准确测量非常重要。目前,国内外测量薄膜材料相变温度的主要方法有变温X射线衍射法和差示扫描量热法,前者测量精度有限,后者是破坏性测量。本文根据薄膜材料相变前后光学性质会发生较大改变的特性,首先设计了薄膜材料相变温度测量仪的硬件部分,主要包含高温加热炉、样品台、光路模块等;其次探究了高温加热炉腔的温场均匀性及温度模块的控制能力,结果表明均符合实验要求;最后,利用此装置测量了典型硫系材料GeTe和Ge_(2)Sb_(2)Te_(5)薄膜的相变温度,10次测量平均值分别为212.7℃和145.4℃,标准偏差分别为1.70和2.32,测量结果稳定性良好,达到实验预期。 展开更多
关键词 相变存储器 相变温度 高温加热炉 光功率 光功率测量法
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基于虚拟现实的轨道交通车辆数字孪生仿真系统
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作者 肖罡 廖琴 +3 位作者 杨钦文 张蔚 赵斯杰 黄晋 《城市轨道交通研究》 北大核心 2024年第3期135-139,共5页
[目的]为了提高轨道交通车辆仿真系统的可视化与交互性,依托VR(虚拟现实)技术,构建了轨道交通车辆数字孪生仿真平台。[方法]通过轨道交通车辆数字孪生三维模型与机理模型的层级式构建方法,以及层级式关联映射方法,实现了三维模型与机理... [目的]为了提高轨道交通车辆仿真系统的可视化与交互性,依托VR(虚拟现实)技术,构建了轨道交通车辆数字孪生仿真平台。[方法]通过轨道交通车辆数字孪生三维模型与机理模型的层级式构建方法,以及层级式关联映射方法,实现了三维模型与机理模型融合,耦合生成了轨道交通车辆数字孪生三维物理模型,并由此提出了一种轨道交通车辆数字孪生仿真系统以及系统的构建方法。以青岛某地铁车辆及其相应运行线路为研究对象,通过搭建的VR平台及车辆自动驾驶控制算法,对该仿真系统功能进行了试验验证。[结果及结论]试验表明,列车实际运行速度与控制运行速度误差均在±1.5 km/h内,证实了模型的有效性。轨道交通车辆数字孪生仿真平台的构建方法为提升轨道交通车辆仿真系统的可视化与交互性提供了新的技术思路。 展开更多
关键词 轨道交通 车辆 数字孪生 仿真系统 虚拟现实
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用于聚合物粉末微量水分测定的微波谐振腔体设计与测试
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作者 伍国柱 胡玉荣 +3 位作者 乔晓婷 黄辉 王俊雄 宋振飞 《传感技术学报》 CAS CSCD 北大核心 2024年第5期913-915,共3页
主要研究了用于聚合物材料含水率测量的同轴谐振腔设计与测试,加工完成的谐振腔空腔谐振频率为3.38 GHz,负载Q值为3328。选取了0.06%和0.24%两种含水率聚四氟乙烯粉末,通过分析粉末体积占比与混合介电常数和负载Q值的关系来验证谐振腔... 主要研究了用于聚合物材料含水率测量的同轴谐振腔设计与测试,加工完成的谐振腔空腔谐振频率为3.38 GHz,负载Q值为3328。选取了0.06%和0.24%两种含水率聚四氟乙烯粉末,通过分析粉末体积占比与混合介电常数和负载Q值的关系来验证谐振腔对于微量含水率粉末的分辨力,测试结果显示了设计的谐振腔能够有效用于微量含水率范围内的粉末含水率分辨,并且有潜力通过负载Q值进行含水率精密测量。 展开更多
关键词 微波测量 同轴谐振腔 粉末含水率 介电常数 品质因素 粉末体积占比
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Effects of Initial and Boundary Conditions on Heavy Rainfall Simulation over the Yellow Sea and the Korean Peninsula:Comparison of ECMWF and NCEP Analysis Data Effects and Verification with Dropsonde Observation
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作者 Jiwon HWANG Dong-Hyun CHA +2 位作者 Donghyuck YOON Tae-Young GOO Sueng-Pil JUNG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第9期1787-1803,共17页
This study evaluated the simulation performance of mesoscale convective system(MCS)-induced precipitation,focusing on three selected cases that originated from the Yellow Sea and propagated toward the Korean Peninsula... This study evaluated the simulation performance of mesoscale convective system(MCS)-induced precipitation,focusing on three selected cases that originated from the Yellow Sea and propagated toward the Korean Peninsula.The evaluation was conducted for the European Centre for Medium-Range Weather Forecasts(ECMWF)and National Centers for Environmental Prediction(NCEP)analysis data,as well as the simulation result using them as initial and lateral boundary conditions for the Weather Research and Forecasting model.Particularly,temperature and humidity profiles from 3D dropsonde observations from the National Center for Meteorological Science of the Korea Meteorological Administration served as validation data.Results showed that the ECMWF analysis consistently had smaller errors compared to the NCEP analysis,which exhibited a cold and dry bias in the lower levels below 850 hPa.The model,in terms of the precipitation simulations,particularly for high-intensity precipitation over the Yellow Sea,demonstrated higher accuracy when applying ECMWF analysis data as the initial condition.This advantage also positively influenced the simulation of rainfall events on the Korean Peninsula by reasonably inducing convective-favorable thermodynamic features(i.e.,warm and humid lower-level atmosphere)over the Yellow Sea.In conclusion,this study provides specific information about two global analysis datasets and their impacts on MCS-induced heavy rainfall simulation by employing dropsonde observation data.Furthermore,it suggests the need to enhance the initial field for MCS-induced heavy rainfall simulation and the applicability of assimilating dropsonde data for this purpose in the future. 展开更多
关键词 initial conditions dropsonde heavy rainfall forecast global model analysis evaluation
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A review on ultra-small undoped MoS_(2) as advanced catalysts for renewable fuel production
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作者 Guoping Liu Lingling Ding +6 位作者 Yuxuan Meng Ahmad Ali Guifu Zuo Xianguang Meng Kun Chang Oi Lun Li Jinhua Ye 《Carbon Energy》 SCIE EI CAS CSCD 2024年第2期92-112,共21页
Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-... Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-performance catalysts.The synthesis of ultra-small MoS2 particles(<10 nm)is highly desired in various experimental studies.The ultra-small structure could often lead to a distinct S-Mo coordination state and nonstoichiometric composition in MoSx,minimizing in-plane active sites of the 2D structure and making it probable to regulate the atomic and electronic structure of its intrinsic active sites on a large extent,especially in MoSx clusters.This article summarizes the recent progress of catalysis over ultra-small undoped MoS_(2) particles for renewable fuel production.Through a systematic review of their synthesis,structural,and spectral characteristics,as well as the relationship between their catalytic performance and inherent defects,we aim to provide insights into catalysis over this matrix that may potentially enable advancement in the development of high-performance MoS_(2)-based catalysts for sustainable energy generation in the future. 展开更多
关键词 applications CATALYTIC MoS_(2) structure synthesis
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Superconducting joints using reacted multifilament MgB_(2)wires:A technology toward cryogen-free MRI magnets
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作者 Dipak Patel Akiyoshi Matsumoto +8 位作者 Hiroaki Kumakura Yuka Hara Toru Hara Minoru Maeda Hao Liang Yusuke Yamauchi Seyong Choi Jung Ho Kim Md Shahriar A.Hossain 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第1期159-170,共12页
The development of superconducting joining technology for reacted magnesium diboride(MgB_(2))conductors remains a critical challenge for the advancement of cryogen-free MgB_(2)-based magnets for magnetic resonance ima... The development of superconducting joining technology for reacted magnesium diboride(MgB_(2))conductors remains a critical challenge for the advancement of cryogen-free MgB_(2)-based magnets for magnetic resonance imaging(MRI).Herein,the fabrication of superconducting joints using reacted carbon-doped multifilament MgB_(2)wires for MRI magnets is reported.To achieve successful superconducting joints,the powder-in-mold method was employed,which involved tuning the filament protection mechanism,the powder compaction pressure,and the heat treatment condition.The fabricated joints demonstrated clear superconducting-to-normal transitions in self-field,with effective magnetic field screening up to 0.5 T at 20 K.To evaluate the interface between one of the MgB_(2)filaments and the MgB_(2)bulk within the joint,serial sectioning was conducted for the first time in this type of superconducting joint.The serial sectioning revealed space formation at the interface,potentially caused by the volume shrinkage associated with the MgB_(2)formation or the combined effect of the volume shrinkage and the different thermal expansion coefficients of the MgB_(2)bulk,the filament,the mold,and the sealing material.These findings are expected to be pivotal in developing MgB_(2)superconducting joining technology for MRI magnet applications through interface engineering. 展开更多
关键词 Mg B2 superconducting joint MgB_(2)conductor MRI applications Cryogen-free magnet Persistent-mode operation
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Is platinum-loaded titania the best material for dye-sensitized hydrogen evolution under visible light?
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作者 Haruka Yamamoto Langqiu Xiao +5 位作者 Yugo Miseki Hiroto Ueki Megumi Okazaki Kazuhiro Sayama Thomas E.Mallouk Kazuhiko Maeda 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第8期124-132,共9页
A dye-sensitized photocatalyst combining Pt-loaded TiO_(2) and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)N... A dye-sensitized photocatalyst combining Pt-loaded TiO_(2) and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)Nb_(3)O_(10) nanosheets.When the sacrificial donor ethylenediaminetetraacetic acid(EDTA)disodium salt dihydrate was used,RuP/Pt/TiO_(2) showed higher activity than RuP/Pt/HCa_(2)Nb_(3)O_(10).In contrast,when NaI(a reversible electron donor)was used,RuP/Pt/TiO_(2) showed little activity due to back electron transfer to the electron acceptor(I_(3)-),which was gener-ated as the oxidation product of I-.By modification with anionic polymers(sodium poly(styrenesulfonate)or sodium polymethacrylate)that could inhibit the scavenging of conduction band electrons by I_(3)-,the H_(2) production activity from aqueous NaI was improved,but it did not exceed that of RuP/Pt/HCa_(2)Nb_(3)O_(10).Transient absorption measurements showed that the rate of semiconductor-to-dye back electron transfer was slower in the case of TiO_(2) than HCa_(2)Nb_(3)O_(10),but the electron transfer reaction to I3-was much faster.These results indicate that Pt/TiO_(2) is useful for reactions with sacrificial reductants(e.g.,EDTA),where the back electron transfer reaction to the more reducible product can be neglected.However,more careful design of the catalyst will be nec-essary when a reversible electron donor is employed. 展开更多
关键词 Artificial photosynthesis Solar fuel Water splitting Z-scheme
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Boron Nitride-Integrated Lithium Batteries:Exploring Innovations in Longevity and Performance
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作者 Shayan Angizi Sayed Ali Ahmad Alem +3 位作者 Mahdi Torabian Maryam Khalaj Dmitri Golberg Amir Pakdel 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第6期13-40,共28页
The current global warming,coupled with the growing demand for energy in our daily lives,necessitates the development of more efficient and reliable energy storage devices.Lithium batteries(LBs)are at the forefront of... The current global warming,coupled with the growing demand for energy in our daily lives,necessitates the development of more efficient and reliable energy storage devices.Lithium batteries(LBs)are at the forefront of emerging power sources addressing these challenges.Recent studies have shown that integrating hexagonal boron nitride(h-BN)nanomaterials into LBs enhances the safety,longevity,and electrochemical performance of all LB components,including electrodes,electrolytes,and separators,thereby suggesting their potential value in advancing eco-friendly energy solutions.This review provides an overview of the most recent applications of h-BN nanomaterials in LBs.It begins with an informative introduction to h-BN nanomaterials and their relevant properties in the context of LB applications.Subsequently,it addresses the challenges posed by h-BN and discusses existing strategies to overcome these limitations,offering valuable insights into the potential of BN nanomaterials.The review then proceeds to outline the functions of h-BN in LB components,emphasizing the molecular-level mechanisms responsible for performance improvements.Finally,the review concludes by presenting the current challenges and prospects of integrating h-BN nanomaterials into battery research. 展开更多
关键词 ELECTRODE ELECTROLYTE hexagonal boron nitride lithium battery SEPARATOR
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Harvesting Energy Via Water Movement and Surface Ionics in Microfibrous Ceramic Wools
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作者 Manpreet Kaur Avinash Alagumalai +3 位作者 Omid Mahian Sameh M.Osman Tadaaki Nagao Zhonglin Wang 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第6期332-341,共10页
Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,... Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents.To address this challenge,our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation.The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer.This occurrence bears resemblance to the natural water transpiration in plants,thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner.The generator module demonstrated in this study,measuring 12×6 cm^(2),exhibited a noteworthy open-circuit voltage of 0.35 V,coupled with a short-circuit current of 0.51 mA.Such low-cost ceramic wools are suitable for ubiquitous,permanent energy sources and hold potential for use as self-powered sensors and systems,eliminating the requirement for external energy sources such as sunlight or heat. 展开更多
关键词 ceramic microfibers energy harvesting power generation self-powered systems water evaporation
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Lithium Ion Transport Environment by Molecular Vibrations in Ion-Conducting Glasses
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作者 Hiroki Yamada Koji Ohara +20 位作者 Satoshi Hiroi Atsushi Sakuda Kazutaka lkeda Takahiro Ohkubo Kengo Nakada Hirofumi Tsukasaki Hiroshi Nakajimai Laszlo Temleitner Laszlo Pusztai Shunsuke Ariga Aoto Matsuo Jiong Ding Takumi Nakano Takuya Kimura Ryo Kobayashi Takeshi Usuki Shuta Tahara Koji Amezawa Yoshitaka Tateyama Shigeo Mori Akitoshi Hayashi 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第3期133-142,共10页
Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all-solid-state batteries,a promising technology for electric vehicles.In this context,Li_(3)PS_(4)glass,a promising solid ele... Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all-solid-state batteries,a promising technology for electric vehicles.In this context,Li_(3)PS_(4)glass,a promising solid electrolyte candidate,exhibits dynamic coupling between the Li^(+)cation mobility and the PS_(4)^(3-)anion libration,which is commonly referred to as the paddlewheel effect.In addition,it exhibits a concerted cation diffusion effect(i.e.,a cation-cation interaction),which is regarded as the essence of high Li ion transport.However,the correlation between the Li^(+)ions within the glass structure can only be vaguely determined,due to the limited experimental information that can be obtained.Here,this study reports that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyze the chemical bonds.It is found that three types of Li ions are present in Li_(3)PS_(4)glass,and that the more mobile Li ions(i.e.,the Li3-type ions)exhibit a characteristic correlation at relatively long distances of 4.0-5.0A.Furthermore,reverse Monte Carlo simulations combined with deep learning potentials that reproduce X-ray,neutron,and electron diffraction pair distribution functions showed an increase in the number of Li3-type ions for partially crystallized glass structures with improved Li ion transport properties.Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences.Thus,considering the molecular vibrations in the glass during the evaluation of the Li ion valences is expected to lead to the development of new solid electrolytes. 展开更多
关键词 electrolytes ionic conductors MODELING molecular dynamics
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基于暗场线扫技术的球体表面缺陷检测技术 被引量:1
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作者 黄涵 史舟淼 +2 位作者 施玉书 张树 胡佳成 《光子学报》 EI CAS CSCD 北大核心 2023年第12期99-111,共13页
钢球的球体几何特性令表面上的缺陷难以连贯成像引起漏检或缺陷畸变被误判,且钢球的镜面反射效应可能造成缺陷信号被周围环境的像和高反亮斑淹没,导致缺陷漏检。为此,提出了一种基于光学暗场线扫描技术的钢球表面缺陷检测方法,设计搭建... 钢球的球体几何特性令表面上的缺陷难以连贯成像引起漏检或缺陷畸变被误判,且钢球的镜面反射效应可能造成缺陷信号被周围环境的像和高反亮斑淹没,导致缺陷漏检。为此,提出了一种基于光学暗场线扫描技术的钢球表面缺陷检测方法,设计搭建了一套适用于高反射率钢球的暗场线扫表面缺陷检测系统,开发了图像预处理、畸变校正、缺陷提取、点云重建、分割和过滤等算法,建立球面图像点间的空间几何关系,成功将钢球表面缺陷在三维球面上重构,实现了轴承钢球表面缺陷的三维连贯检测。实验结果表明,对表面完好的无损球测量重复性为0.14%,对表面带有缺陷的磨损球测量重复性为0.11%。 展开更多
关键词 图像处理 球面缺陷检测 暗场线扫描 钢球 球面三维重建
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文献挖掘和高通量方法优化碳纳米管垂直阵列生长 被引量:1
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作者 高张丹 吉忠海 +5 位作者 张莉莉 汤代明 邹孟珂 谢蕊鸿 刘少康 刘畅 《新型炭材料(中英文)》 SCIE EI CAS CSCD 北大核心 2023年第5期887-897,共11页
具有良好力学性能和高导热性的碳纳米管垂直阵列(VACNT)可用作热管理中的有效热界面材料。为了利用沿碳纳米管轴向的高导热性,需要优化碳纳米管垂直阵列的结晶度和高度。然而,碳纳米管垂直阵列的生长参数空间(如退火时间、催化剂种类、... 具有良好力学性能和高导热性的碳纳米管垂直阵列(VACNT)可用作热管理中的有效热界面材料。为了利用沿碳纳米管轴向的高导热性,需要优化碳纳米管垂直阵列的结晶度和高度。然而,碳纳米管垂直阵列的生长参数空间(如退火时间、催化剂种类、生长温度、载气、碳源等)复杂,结构特征之间相互影响,同时提高碳纳米管垂直阵列的高度和质量仍是一个巨大的挑战。与此同时,缺乏对参数调控方向的指导进一步增加了实验结果的不确定性,并限制了产物结构优化的效率。本研究开发了一种文献挖掘-机器学习-高通量制备策略,有效优化了碳纳米管垂直阵列的高度和质量。为了揭示碳纳米管垂直阵列结构与关键生长参数之间的潜在关系,采用随机森林回归算法对一组已发布的样本数据(864个样本)进行建模,并利用机器学习模型解释包SHAP(SHapley Additive exPlanations)分析获得影响垂直阵列高度和结晶度的主要生长参数。经分析确定,高通量实验旨在调节4个关键参数:生长温度、生长时间、催化剂组分和碳源浓度。结果发现,经筛选的Fe/Gd/Al_(2)O_(3)催化剂能够生长出具有毫米级高度和更高结晶度的碳纳米管垂直阵列。结果表明,文献挖掘、高通量实验和基于数据的机器学习可以有效地处理碳纳米管生长等多参数过程,提高对结构的控制。 展开更多
关键词 碳纳米管垂直阵列 控制制备 文献挖掘 机器学习 高通量
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化学气相沉积石墨烯/铜合金制备与导电、耐磨性能研究 被引量:2
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作者 戴丹 杨科 +5 位作者 叶辰 虞锦洪 邓丽芬 李惠敏 江南 林正得 《铜业工程》 CAS 2023年第4期78-84,共7页
通过原位化学气相沉积(CVD)技术,在铜粉上包覆石墨烯,再通过真空热压技术制备出石墨烯/铜合金。研究表明:铜晶粒表面包覆了高质量的石墨烯。在铜粉表面原位生长的石墨烯均匀分散在铜晶粒的晶界处,而且石墨烯的含量低,只占0.04%(质量分数... 通过原位化学气相沉积(CVD)技术,在铜粉上包覆石墨烯,再通过真空热压技术制备出石墨烯/铜合金。研究表明:铜晶粒表面包覆了高质量的石墨烯。在铜粉表面原位生长的石墨烯均匀分散在铜晶粒的晶界处,而且石墨烯的含量低,只占0.04%(质量分数)。石墨烯/铜合金具有高的导电性能,导电率高达97%IACS。同时,石墨烯/铜合金的摩擦系数降低到0.46,与铜相比降低了38.7%。石墨烯/铜合金的磨损率降低到2.09×10^(-4)mm^(3)/(N·m),与铜相比降低了68.6%。 展开更多
关键词 石墨烯/铜 化学气相沉积 原位 导电性 耐磨性
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Additive manufacturing of promising heterostructure for biomedical applications 被引量:5
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作者 Cijun Shuai Desheng Li +2 位作者 Xiong Yao Xia Li Chengde Gao 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2023年第3期363-405,共43页
As a new generation of materials/structures,heterostructure is characterized by heterogeneous zones with dramatically different mechanical,physical or chemical properties.This endows heterostructure with unique interf... As a new generation of materials/structures,heterostructure is characterized by heterogeneous zones with dramatically different mechanical,physical or chemical properties.This endows heterostructure with unique interfaces,robust architectures,and synergistic effects,making it a promising option as advanced biomaterials for the highly variable anatomy and complex functionalities of individual patients.However,the main challenges of developing heterostructure lie in the control of crystal/phase evolution and the distribution/fraction of components and structures.In recent years,additive manufacturing techniques have attracted increasing attention in developing heterostructure due to the unique flexibility in tailored structures and synthetic multimaterials.This review focuses on the additive manufacturing of heterostructure for biomedical applications.The structural features and functional mechanisms of heterostructure are summarized.The typical material systems of heterostructure,mainly including metals,polymers,ceramics,and their composites,are presented.And the resulting synergistic effects on multiple properties are also systematically discussed in terms of mechanical,biocompatible,biodegradable,antibacterial,biosensitive and magnetostrictive properties.Next,this work outlines the research progress of additive manufacturing employed in developing heterostructure from the aspects of advantages,processes,properties,and applications.This review also highlights the prospective utilization of heterostructure in biomedical fields,with particular attention to bioscaffolds,vasculatures,biosensors and biodetections.Finally,future research directions and breakthroughs of heterostructure are prospected with focus on their more prospective applications in infection prevention and drug delivery. 展开更多
关键词 additive manufacturing HETEROSTRUCTURE synergistic effects integrated properties biomedical applications
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Strengths,weaknesses,opportunities,and threats(SWOT)analysis of supercapacitors:A review 被引量:3
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作者 Pragati A.Shinde Qaisar Abbas +3 位作者 Nilesh R.Chodankar Katsuhiko Ariga Mohammad Ali Abdelkareem Abdul Ghani Olabi 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第4期611-638,共28页
The development of clean and sustainable energy sources has received widespread interest in the past few decades due to the rolling energy demands while extenuating the rising tiers of greenhouse gases and environment... The development of clean and sustainable energy sources has received widespread interest in the past few decades due to the rolling energy demands while extenuating the rising tiers of greenhouse gases and environmental pollution.Due to their intermittent nature,these green and sustainable sources require appropriate energy storage systems.Amongst different energy storage technologies,electrochemical energy storage devices,particularly supercapacitors(SCs),have fascinated global attention for their utilization in electric vehicles,power supports,portable electronics,and many others application requiring electric energy devices for their operation.Thus,the growth of SCs in the commercial market has squeezed requirements,and further developments are obligatory for their effective industrialization.In the meantime,SCs also face technical complications and contests for their introduction in industrial settings because of their low energy density and high Levelized cost.The present study combines core strengths,weaknesses,opportunities,and threats(SWOT)analysis of SCs with new perspectives and recent ideas.The challenges and the future progressive prospects of SCs are also presented in detail.This review will afford consistent direction and new superhighways for the further development of SCs as standalone and complementary energy storage systems. 展开更多
关键词 SUPERCAPACITORS Energy storage Strengths OPPORTUNITIES
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