检索结果-南通市图书馆

Tempering stability of Fe–Cr–Mo–W–V hot forging die steels

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2017年第10期24卷 1145-1157页

作者： Yuan-ji shi Xiao-chun Wu Jun-wan Li Na Min School of Materials Science and Engineering Shanghai University Shanghai 200072 China

The tempering stability of three Fe–Cr–Mo–W–V hot forging die steels(DM, H21, and H13) was investigated through hardness measurements and transmission electron microscopy(TEM) observations. Both dilatometer tests and TEM observations revealed that DM steel has a higher tempering stability than H21 and H13 steels because of its substantial amount of M_2C(M represents metallic element) carbide precipitations. The activation energies of the M_2C carbide precipitation processes in DM, H21, and H13 steels are 236.4, 212.0, and 228.9 kJ/mol, respectively. Furthermore, the results indicated that vanadium atoms both increase the activation energy and affect the evolution of M_2C carbides, resulting in gradual dissolution rather than over-aging during tempering.

关键词： tempering stability hot forging die steels carbide precipitation

Evolutionary selection for regression test cases based on diversity

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2021年第2期15卷 201-203页

作者： Baoying MA Li wan Nianmin yao Shuping FAN Yan ZHANG School of Health Management Mudanjiang Medical UniversityMudanjiang157011China Department of intelligence and Computing Tianjin UniversityTianjin300350China School of Computer Science and Technology Dalian University of TechnologyDalian116024China School of Computer and Information Technology Mudanjiang Normal UniversityMudanjiang157011China

1 Introduction Regression testing refers to retest code after modification to ensure that changes will not introduce new faults or cause faults in other lines of code[1].Regression test selection(RTS)is one of the predominant *** identifies test cases that are relevant to test recent changes in an application and seeks to reduce the number of test suite while preserving the capability to reveal faults[2].

关键词： preserving predominant changes

Evaluation of social network conservation in historical areas of mountainous towns in Chongqing, China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2020年第7期17卷 1763-1775页

作者： shi Ya-ling HUANG Yong HU Dong-yang wan Dan Faculty of Architecture and Urban Planning Chongqing UniversityChongqing400030China The Bartlett School of Construction and Project Management University College London1-19 Torrington PlaceLondonWC1E 7HBUK Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing400030China Chongqing University Planning&Design Institute Co. LtdChongqing400044China

Over recent decades,historical areas conservation has become an important strategy to improve urban competitiveness in the global *** shown in existing studies that the conservation of historical areas mainly focused on the physical environment,there is still room for the non-physical study,and researches on the social network conservation in mountainous historical areas are particularly ***,this paper aims to establish an evaluation system which is helpful for the social network conservation of historical *** evaluation system is based on social network analysis and the information of social relationships gathered in field surveys using a specifically designed questionnaire method in four mountainous towns in Chongqing,*** it was analyzed from three perspectives,i.e.,by the basic statistical properties,condensate subgroup,and *** five analysis indicators were conceived,including density,lambda set,k-core,degree centrality,and betweenness *** analysis results demonstrate that the social networks of the four towns show different indicators,which are respectively relevant to completeness degree,edgerelatedness level,local stability,structural balance,and concentrated trend of social *** from SNA modeling indicate that neighborhood residents of historical areas who have more stable and healthier social relationships are relatively not easily be *** results also illustrate that the social networks structure is influenced by the terrain,form,and function of historical areas,and the change of historical areas is caused by"individual-family-society".Finally,the strategies guiding the social network conservation are put forward from two *** findings suggest that the conservation and management of social network and aborigines in historical areas should be emphasized to increase the collective benefits and vitality.

关键词： Historical areas Social network analysis Physical environment Evaluation Conservation Mountainous towns

A chiral salen-Co(Ⅱ)complex as soluble redox mediator for promoting the electrochemical performance of Li-O_(2) batteries

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第9期15卷 8101-8108页

作者： Hao wan Yingjie Sun Jia Yu Qianqi shi Yongchun Zhu Yitai Qian Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry University of Science and Technology of ChinaHefei 230026China Hebei Key Laboratory of Photoelectric Control on Surface and Interface College of ScienceHebei University of Science and TechnologyShijiazhuang 050018China Materials Genome Institute Shanghai UniversityShanghai 200444China

Low discharge capacity and poor cycle stability are the major obstacles hindering the operation of Li-O_(2)batteries with *** obstacles are mainly caused by the cathode passivation behaviours and the accumulation of *** the discharge process in solution and accelerating the decomposition of discharge products and by-products are able to alleviate above problems to some ***,chiral salen-Co(Ⅱ)complex,(1R,2R)-(-)-N,N-bis(3,5-di-t-butylsalicylidene)-1,2-cyclohexanediaminocobalt(Ⅱ)(Co(Ⅱ))as a multi-functional redox mediator was introduced into electrolyte to induce solution phase formation of Li_(2)O_(2)and catalyze the oxidation of Li_(2)O_(2)and main by-products Li_(2)*** to the Co(Ⅱ)has the solvation effect towards Li+,it can drive solution phase formation of Li_(2)O_(2),to prevent electrode from passivation and then increase the discharge capacity with a high Li_(2)O_(2)yield of 96.09%.Furthermore,the Co(Ⅱ)possesses suitable redox couple potentials,and it does so while simultaneously boosting the oxidization of Li_(2)O_(2)and the decomposition of Li_(2)CO3,reducing charge overpotential,and promoting cycle ***,a cell with Co(Ⅱ)achieved a long cycling stability at low charge plateau(3.66 V)over 252 cycles with a specific capacity of 500 mAh·gcarbon^(−1).

关键词： chiral salen-Co(Ⅱ)complex soluble redox mediator multi-redox potential trifunctional Li-O_(2)batteries

Divergence-degenerate spatial multiplexing towards future ultrahigh capacity,low error-rate optical communications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2022年第6期11卷 1253-1263页

作者： Zhensong wan Yijie Shen Zhaoyang wang Zijian shi Qiang Liu Xing Fu Key Laboratory of Photonic Control Technology(Tsinghua University) Ministry of Education100084 BeijingChina State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua University100084 BeijingChina Optoelectronics Research center University of SouthamptonSouthampton SO171BJUK

Spatial mode(de)multiplexiing of orbital angular momentum(OAM)beams is a promising solution to address future bandwidth issues,but the rapidly increasing divergence with the mode order severely limits the practically addressable number of OAM *** we present a set of multi-vortex geometric beams(MVGBs)as high-dimensional information carriers for free-space optical communication,by virtue of three independent degrees of freedom(DoFs)including central OAM,sub-beam OAM,and coherent-state *** novel modal basis set has high divergence degeneracy,and highly consistent propagation behaviors among all spatial modes,capable of increasing the addressable spatial channels by two orders of magnitude than OAM basis as *** experimentally realize the tri-DoF MVGB mode(de)multiplexing and data transmission by the conjugated modulation method,demonstrating lower error rates caused by center offset and coherent background noise,compared with OAM *** work provides a potentially useful basis for the next generation of large-scale dense data communication.

关键词： optical error coherent

Acceptorless dehydrogenative amination of alkenes for the synthesis of N-heterocycles

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2022年第7期65卷 1330-1337页

作者： Jia-Lin Tu wan Tang shi-Hui He Ma Su Feng Liu Jiangsu Key Laboratory of Neuropsychiatric Diseases and Department of Medicinal Chemistry College of Pharmaceutical SciencesSoochow UniversitySuzhou 215123China Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Catalytic amination of alkenes is one of the most attractive reactions for the construction of complex heterocycles with nitrogen centers. Herein, we present that synergistic photoredox and cobaloxime catalysis allows for highly efficient and mild dehydrogenative reactions between various NH nucleophiles and di-, tri-, and tetrasubstituted alkenes in the absence of external oxidants, thus enabling access to an array of N-heterocycles. Notably, both Z-and E-alkene-containing N-heterocycles are accessible. Mechanistic studies indicated that the Z-cinnamyl derivatives could be generated by photocatalytic E to Z alkene isomerization through an energy transfer process. Moreover, we find that sluggish energy transfer could inhibit the E to Z alkene isomerization process, thus offering the cinnamyl derivatives with E-selectivity. Our results highlight the benefits of the reactions using dual photoredox and cobaloxime catalysis to lead to diverse N-heterocycles.

关键词： nitrogen-centered radical alkene amination photoredox cyclization N-heterocycle

同方期刊数据库

Corrosion behavior of Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) high-entropy alloy coating via 3D printing laser cladding in a sulphur environment

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第1期60卷 197-205页

作者： Hongxia wan Dongdong Song Xiaolei shi Yong Cai Tingting Li Changfeng Chen Beijing Key Laboratory of Failure Corrosion and Protection of Oil/Gas Facility MaterialsDepartment of Materials Science and EngineeringChina University of Petroleum(Beijing)Beijing 102249China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China

High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase *** are constructed with five or more principal alloying elements in equimolar or near-equimolar ***,they can derive their performance from multiple principal elements ratherthan a single *** this work,three-dimensional printing laser cladding was applied to produce an Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) HEA *** experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 μm in *** the high-temperature laser cladding process,some Fe elements diffused from the substrate to the coating,forming a combination of face-centred cubic and body-centred cubic phase *** HEA coating metallurgically bonded well with the *** to the increased dislocation density and number of grain boundaries,the HEA coating was harder and had a stronger hydrophobicity than X70 *** electrochemistry results showed that the HEA coating had better corrosion resistance than X70 *** oxides formed on the surface of the HEA coating had a certain protective ***,because of the laser cladding,the HEA coating generated *** future work,the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks.

关键词： High-entropy alloy coating(HEA coating) Laser cladding Corrosion behaviour

Molecular Simulations in Macromolecular Science

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第9期41卷 1361-1370,I0005页

作者： Duo Xu Hai-Xiao wan Xue-Rong yao Juan Li Li-Tang Yan State Key Laboratory of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing100084China Beijing Research Institute of Chemical Industry SINOPECBeijing100013Chin

Molecular simulations are now an essential part of modern chemistry and physics,especially for the investigation of *** have evolved into mature approaches that can be used effectively to understand the structure-to-property relationships of diverse macromolecular *** this article,we provide a tutorial on molecular simulations,focusing on the technical and practical *** prominent and classical simulation methods and software are *** applications of molecular simulations in various directions of macromolecular science are thenfeatured by representative systems,including self-assembly,crystallization,chemical reaction,and some typical non-equilibrium *** tutorial paper provides a useful overview of molecular simulations in the rapid progress of macromolecular science,and suggests guidance for researchers who start exploiting molecular simulations in their study.

关键词： Molecular simulation Coarse-grained molecular dynamics Multi-scale method Polymer physics

Feasibility evaluation of failure models for predicting forming limit of metal foils

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第9期33卷 2461-2471页

作者： Bao MENG Jiejie shi Yiyun ZHANG Cheng CHENG Bolin MA Min wan School of Mechanical Engineering and Automation Beihang UniversityBeijing 100083China

Forming limit of metal foil is an important index to evaluate its formability,and is of considerable significance to improve the quality of *** ductile fracture(DF)behavior in microscale plastic deformation is remarkably affected by the geometry and grain *** explore the size-dependent forming limit curve(FLC),the Holmberg and Marciniak tests of SUS304 foils with the thicknesses of less than 0.1 mm and diverse grain sizes were *** addition,the validity and feasibility of three types of existing failure models including Swift/Hill,MarciniakKuczynski(M-K)and DF criteria for predicting the micro-scaled FLCs were *** is found that the Swift/Hill model possesses the worst accuracy with predicting deviation above 50%.Four classical DF criteria including Freudenthal,Ayada,Brozzo and Oh show great difference,and Oh model considering plastic anisotropy presents the best *** predicted deviation of M-K model is aggravated with increasing grain size and decreasing foil thickness,which is attributed to the intensified free surface roughening and transformation of fracture mechanism with *** research thus provides a deeper understanding and valuable reference for the widespread application of FLC in microforming.

关键词： Failure criteria Forming limit Metal foil Microforming Size effect