检索结果-南通市图书馆

International Journal of Minerals,Metallurgy and Materials 2013年第2期20卷 180-186页

作者： Hui Chen Cheng-chang Jia shang-jie li School of Materials Science and Engineering University of Science and Technology Beijing Shenzhen Haimingrun Industrial Co. Ltd.

Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature （HPHT） infiltration technique. Their microstructural evolution and thermal conductivity were presented as a function of sintering parameters （temperature, pressure, and time）. The improvement in interfacial bonding strength and the maximum thermM conductivity of 750 W/（m.K） were achieved at the optimal sintering parameters of 1200℃, 6 GPa and 10 min. It is found that the thermal conductivity of the composites depends strongly on sintering pressure. When the sintering pressure is above 6 GPa, the diamond skeleton is detected, which greatly contributes to the excellent thermal conductivity.

关键词： metallic matrix composites particle reinforced composites copper diamonds infiltration microstructuralevolution thermal conductivity

Selective interfacial bonding and thermal conductivity of diamond/Cu-alloy composites prepared by HPHT technique

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第4期19卷 364-371页

作者： Hui Chen Cheng-chang Jia shang-jie li Xian Jia Xia Yang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Shenzhen Haimingrun Industrial Co. Ltd. Shenzhen 518126 China

Cu-based and Cu-alloy-based diamond composites were made by high-pressure-high-temperature （HPHT） sintering with the aim of maximizing the thermal conductivity of the composites. Improvements in interfacial bonding strength and thermo-physical properties of the composites were achieved using an atomized copper alloy with minor additions of Co, Cr, 13, and Ti. The thermal conductivity （TC） oh- mined exhibited as high as 688 W.m-1.K-1, but also as low as 325 W.m-1.K-l. A large variation in TC can be rationalized by the discrepancy of diamond-matrix interfacial bonding. It was found from fractography that preferential bonding between diamond and the Cu-alloy matrix occurred only on the diamond {100} faces. EDS analysis and Raman spectra suggested that selective interfacial bonding may be attributed to amorphous carbon increasing the wettability between diamond and the Cu-alloy matrix. Amorphous carbon was found to significantly affect the TC of the composite by interface modification.

关键词： metallic matrix composites diamonds copper alloys interfacial bonding thermal conductivity

Coronary anomaly： the single coronary artery

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2010年第7期123卷 972-973页

作者： QIN Xu-guang XIONG Wei-guo LU Chun-peng GONG Cheng-jie shang li-hua Department of Cardiology First Affiliated Hospital of Tsinghua University Beijing 100016 China

Single coronary artery （SCA）, defined as an artery that arises from the arterial trunk and nourishes the entire myocardium, is rare. We report two cases of SCA, one is the fight coronary artery （RCA） originating from the middle of left descending artery （LAD）, and the other is the left main coronary artery （LMCA） arising from the proximal fight coronary artery.

关键词： coronary anomaly single coronary artery coronary angiography percutaneous coronary intervention

Low-profile,low sidelobe array antenna with ultrawide beam coverage for UAV communication

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 Aeronautics 2025年第1期38卷 444-454页

作者： Mei li Zhiliang shang lin PU Ming-Chun TANG Lei ZHU School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China Department of Electrical and Computer Engineering University of MacaoMacao SAR 999078China

This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground *** array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low ***,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source ***,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating *** consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation *** indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer *** concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.

关键词： Array antenna Broad beam Fan beam Low sidelobe level Chebyshev synthesis UAV communication

Cyano migration-mediated radical-polar crossover cyclopropanation

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 241-248页

作者： Ziqiang Wang Yasu Chen jie li Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China Frontiers Science Center for Transformative Molecules Zhangjiang Institute for Advanced Study and Shanghai Key Laboratory for Molecular Engineering of Chiral DrugsShanghai Jiao Tong UniversityShanghai 200240China

We report a novel cyano migration-mediated radical-polar crossover process,whereby both the sulfonylcyanation of aliphatic alkenes and the formation of cyclopropanes are concurrently *** transformation yields a diverse array of multisubstituted cyclopropanes under mild photocatalytic *** studies elucidate that the reaction proceeds via intramolecular nucleophilic substitution,leading to the formation of the cyclopropane derivatives.

关键词： cyclopropanation cyano migration radical-polar crossover radical reactions

Subsection cooling system of hot rolling silicon steel and its industrial application

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2025年第1期32卷 159-170页

作者： Qiu-na Wang Ji-quan Sun li-po Yang Hai-shen Wang li-jie Dong jie-ming li Zhen-yang Zhi Yan-wen Bi National Engineering Research Center of Flat Rolling Equipment University of Science and Technology BeijingBeijing100083China Hot Rolling Department of Qian’an Iron and Steel Corporation Shougang Company LimitedTangshan064404HebeiChina National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

An online subsection cooling method for hot rolling silicon steel was designed to achieve local adjustment of transverse roll ***,it was able to meet the requirements of edge drop of the strip by using the features of online thermal ***,after the new subsection spray beam was installed at the exit of mill,the special local cooling rules were analyzed for altering the thermal crown of roll according to rolling process ***,the dynamic impact of subsection cooling on the local thermal crown could just be obtained according to the measured ***,the heat transfer coefficient was determined by different subsection cooling curves under varied rolling ***,the rolling rhythm and variable conditions were important dynamic factors of transient roll temperature in practical rolling ***,real-time calculation and presetting of the thermal crown were carried out to maximize special requirements of load roll gap on local strip *** this new method,the transient temperature and the thermal crown of roll could be quantitatively controlled *** the practical results showed that the predicted temperature was able to match the measured value by more than 95%.Meanwhile,the adjustable range of thermal crown increased by more than 2.5 ***,the qualification rate of strip edge crown has increased from the original 30%to over 70%.

关键词： Subsection cooling Thermal roll crown Multi-parameter coupling Hot rolling Silicon steel

Numerical simulation for large baseline interferometric imaging altimeter

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2025年第1期16卷 111-126页

作者： jie liu Bo liu Xiaonan An Haifeng Kou Bing li China Academy of Aerospace Science and Innovation

Sea topography information holds significant importance in oceanic research and the climate change detection. Radar imaging altimetry has emerged as the leading approach for global ocean observation,employing synthetic aperture radar(SAR) interferometry to enhance the spatial resolution of Sea topography. Nevertheless, current payload capacity and satellite hardware limitations prevent the extension of the interferometric baseline by enlarging the physical antenna size. This constraint hinders achieving centimeter-level accuracy in interferometric altimetry. To address this challenge, we conducted a numerical simulation to assess the viability of a large baseline interferometric imaging altimeter(LB-IIA). By controlling the baseline within the range of 600-1000 m through spiral orbit design in two satellites and mitigating baseline de-correlation with the carrier frequency shift(CFS) technique, we aimed to overcome the above limitations. Our findings demonstrate the efficacy of the CFS technique in compensating for baseline decoherence, elevating coherence from less than 0.1 to over 0.85. Concurrently. The height difference accuracy between neighboring sea surfaces reaches 1 cm within a 1 km resolution. This study is anticipated to serve as a foundational reference for future interferometric imaging altimeter development, catering to the demand for high-precision sea topography data in accurate global bathymetry inversion.

关键词： Sea topography Numerical simulation Carrier frequency shift (CFS) Large baseline interferometric imaging altimeter (LB-IIA)

Steady-state and transient investigation of a small pressurized water reactor ACPR50S for different ATFs based on Bamboo-C code

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2025年第1期36卷 192-206页

作者： Kun Zhuang Ying-Zhen Wang li-Na Deng Yong-Zhan Wang Wen shang Si-Peng Wang Department of Nuclear Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Small modular reactors have received widespread attention owing to their inherent safety,low investment,and *** pressurized water reactors(SPWRs)have become important candidates for SMRs owing to their high technological *** the Fukushima accident,research on accident-tolerant fuels(ATFs),which are more resistant to serious accidents than conventional fuels,has gradually *** study analyzes the neutronics and thermal hydraulics of an SPWR(ACPR50S)for different ATFs,BeO+UO_(2)−SiC,BeO+UO_(2)−FeCrAl,U_(3)Si_(2)−SiC,and U_(3)Si_(2)−FeCrAl,based on a PWR fuel management code,the Bamboo-C deterministic *** the steady state,the burnup calculations,reactivity coefficients,power and temperature distributions,and control rod reactivity worth were *** transients of the control rod ejection accident for the two control rods with the maximum and minimum reactivity worth were *** results showed that 5%B-10 enrichment in the wet annular burnable absorbers assembly can effectively reduce the initial reactivity and end-of-life reactivity *** BeO+UO2−SiC core exhibited superior neutronic characteristics in terms of burnup and negative temperature reactivity compared with the other three cases owing to the strong moderation ability of BeO+UO_(2)and low neutron absorption of ***,the U_(3)Si_(2)core had a marginally better power-flattening effect than BeO+UO_(2),and the differential worth of each control rod group was similar between different *** the transient of a control rod ejection,the changes in the fuel temperature,coolant temperature,and coolant density were *** maximum difference was less than 10℃ for the fuel temperature and 2℃ for the coolant temperature.

关键词： ACPR50S Small pressurized water reactor ATF Steady Transient

Advantages of the Multimodel Ensemble Approach for Subseasonal Precipitation Prediction in China and the Driving Factor of the MJO

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2025年第3期42卷 551-563页

作者： li GUO jie WU Qingquan li Xiaolong JIA China Meteorological Administration Key Laboratory for Climate Prediction Studies National Climate CentreBeijing 100081China Collaborative Innovation Centre On Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210066China

Based on the hindcasts from five subseasonal-to-seasonal(S2S)models participating in the S2S Prediction Project,this study evaluates the performance of the multimodel ensemble(MME)approach in predicting the subseasonal precipitation anomalies during summer in China and reveals the contributions of possible driving *** results suggest that while single-model ensembles(SMEs)exhibit constrained predictive skills within a limited forecast lead time of three pentads,the MME illustrates an enhanced predictive skill at a lead time of up to four pentads,and even six pentads,in southern *** on both deterministic and probabilistic verification metrics,the MME consistently outperforms SMEs,with a more evident advantage observed in probabilistic *** superior performance of the MME is primarily attributable to the increase in ensemble size,and the enhanced model diversity is also a contributing *** reliability of probabilistic skill is largely improved due to the increase in ensemble members,while the resolution term does not exhibit consistent ***,the Madden–Julian Oscillation(MJO)is revealed as the primary driving factor for the successful prediction of summer precipitation in China using the *** improvement by the MME is not solely attributable to the enhancement in the inherent predictive capacity of the MJO itself,but derives from its capability in capturing the more realistic relationship between the MJO and subseasonal precipitation anomalies in *** study establishes a scientific foundation for acknowledging the advantageous predictive capability of the MME approach in subseasonal predictions of summer precipitation in China,and sheds light on further improving S2S predictions.

关键词： multimodel ensemble subseasonal predictions summer precipitation S2S model MJO

Combustion aerosols and suspended dust with controlled processes in Lhasa:Elemental analysis and size distribution characteristics

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 Environmental Sciences 2025年第2期148卷 591-601页

作者： Jinglin li Zhuoga Deqing jie liang Tao Guo Jian Yao Wei liu shanghai Institute of Applied Physics Chinese Academy of ScienceShanghai 201800China University of Chinese Academy of Science Beijing 100049China Meteorological Bureau of Tibet Autonomous Region Lhasa 850000China

To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resulting from 7 types of non-fossil pollution *** investigated the concentration and size distribution of trace elements from 7 pollution sources collected in *** Lhasa’s atmospheric particulate matter data,enrichment factors(EFs)have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of *** highest mass concentration of total elements of biomass combustion appeared at PM_(0.4),and the second highest concentration existed in the size fraction 0.4-1μm;the higher proportion(12%)of toxicmetals was produced by biomass *** elemental composition of suspended dust and atmospheric particulate matter was close(except for As and Cd);the highest concentration of elements was all noted in PM_(2.5-10)(PM3-10).Potassium was found to be one of the main biomass *** proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter(0.53%and 3.75%),which indicates that there are other anthropogenic *** EFs analysis showed that the Cr,Cu,Zn,and Pb produced by biomass combustion were highly enriched(EFs>100)in all particle *** EFs of most trace elements increased with decreasing particle size,indicating the greater influence of humanfactors on smaller particles.

关键词： Size distribution Trace elements Particulate matter Enrichment factors Lhasa