检索结果-南通市图书馆

Mineralogy of northern nearside mare basalts

Research in Astronomy and Astrophysics 2019年第4期19卷 33-40页

作者： zhen-Chao Wang Yun-zhao Wu xiao-Meng Zhang Yu Lu Key Laboratory of Surficial Geochemistry Ministry of Education Department of Earth Sciences Nanjing University Key Laboratory of Planetary Sciences Purple Mountain Observatory Chinese Academy of Sciences CAS Center for Excellence in Comparative Planetology Xuzhou Bureau of Land and Resources School of Geographic and Oceanographic Sciences Nanjing University Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application

The mineralogy of mare basalts reflects the chemical composition of the magma source, as well as the physical and chemical environment of the rocks' formation. This is significant for understanding the thermal evolution of the Moon. In this study, the spatial distribution of mineralogy on the lunar northern nearside basalts was mapped using the Moon Mineralogy Mapper(M^3) data. The study area, which is an elongated mare, Mare Frigoris and northern Mare Imbrium, was mapped and characterized into 27 units based on multi-source data, including spectrum, terrain and element abundance. We extracted 177 M^3 spectra from fresh craters. Spectral parameters such as absorption center and band area ratio(BAR)were obtained through data processing. The variation of mafic minerals in this region was acquired by analyzing these parameters. The basaltic units in eastern Mare Frigoris, which are older, have been found to be dominated by clinopyroxene with lower CaO compared to the returned lunar samples; this is similar to older basaltic units in Mare Imbrium. The basaltic units of western Mare Frigoris and Sinus Roris which are younger have been found to be rich in olivine. The late-stage basalts in Oceanus Procellarum and Mare Imbrium show the same feature. These widespread olivine-rich basalts suggest uniqueness in the evolution of the Moon. Geographically speaking, Mare Frigoris is an individual mare, but the magma source region has connections with surrounding maria in consideration of mineral differences between western and eastern Frigoris, as well as mineral similarities with maria at the same location.

关键词： Moon evolution imaging spectroscopy data analysis

来源：

维普期刊数据库

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

Influence Analysis of Machining and Installation Errors on the Radial Stiffness of a Non-Pneumatic Mechanical Elastic Wheel

引用

Chinese Journal of Mechanical Engineering 2018年第4期31卷 92-100页

作者： You-Qun zhao zhen xiao Fen Lin Ming-Min Zhu Yao-Ji Deng Department of Automotive Engineering College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics

Machining and installation errors are unavoidable in mechanical structures. However, the effect of errors on radial stiffness of the mechanical elastic wheel(ME-Wheel) is not considered in previous studies. To this end, the interval mathematical model and interval finite element model of the ME-Wheel were both established and compared with bench test results. The intercomparison of the influence of the machining and installation errors on the ME-Wheel radial stiffness revealed good consistency among the interval mathematical analysis, interval finite element simulation,and bench test results. Within the interval range of the ME-Wheel machining and installation errors, parametric analysis of the combined elastic rings was performed at different initial radial rigidity values. The results showed that the initial radial stiffness of the flexible tire body significantly influenced the ME-Wheel radial stiffness, and the inverse relationship between the hinge unit length or suspension hub and the radial stiffness was nonlinear. The radial stiffness of the ME-Wheel is predicted by using the interval algorithm for the first time, and the regularity of the radial stiffness between the error and the load on the ME-Wheel is studied, which will lay the foundation for the exact study of the ME-Wheel dynamic characteristics in the future.

关键词： Mechanical elastic wheel Stiffness characteristic Errors Interval algorithm Interval finite element

来源：

维普期刊数据库

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

Effect of Y_(2)O_(3) on microstructure and properties of CoCrFeNiTiNb high entropy alloy coating on Ti-6Al-4V surface by laser cladding

引用

Journal of Rare Earths 2024年第3期42卷 586-599,I0006页

作者： zhen Li Wei zhao Kedong Yu Ning Guo Guangchun xiao Zhiming Wang Hui Zhang College of Mechanical Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan250353China Shandong Institute of Mechanical Design and Research Jinan250031China

The effects of Y_(2)O_(3) on the microstructure, microhardness, wear resistance, high-temperature oxidation resistance, hot corrosion resistance, and electrochemical corrosion behaviour of CoCrFeNiTiNb high entropy alloy coatings formed on Ti-6Al-4V alloy surfaces were studied. The results show that the addition of Y_(2)O_(3) changes the proportion of the phase but does not change its type. The average grain size is only 1/4.7 of that of the high entropy alloy(HEA) coating, and the fine-grained strengthening leads to increases in the microhardness and wear resistance of 21.8% and 26.9%, respectively. The addition of Y_(2)O_(3) enhances the denseness and bonding properties of the oxide and corrosion product layers, reducing the oxidation and hot corrosion rates by 60.3% and 40.3%, respectively. The addition of Y_(2)O_(3) doubles the corrosion resistance which is attributed to the refinement of the grains, the increased proportion of HCP and TiN, and the weakening of galvanic coupling corrosion.

关键词： Laser cladding High entropy alloy coatings Rare earths Wear properties High temperature properties Electrochemical corrosion

来源：

维普期刊数据库

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

Reliability analysis of large-diameter high-grade-steel natural gas pipelines under fault action

引用

Petroleum Science 2022年第5期19卷 2387-2398页

作者： xiao-Ting Gu Xue-Rui Zang zhen-Yong Zhang Peng Yang Wen-zhen Miao Ping Cao Bin zhao School of Petroleum Engineering Yangtze UniversityWuhan430100HubeiChina Key Laboratory of Drilling and Production Engineering for Oil and Gas Wuhan430100HubeiChina College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao266580ShandongChina China Petroleum Pipeline Engineering Corporation Langfang065000HebeiChina China Petroleum Pipeline Engineering Co. Ltd.Langfang065000HebeiChina Sinopec Zhongyuan Petroleum Engineering Design Co. Ltd.Zhengzhou450000HenanChina Sinopec Jianghan Petroleum Engineering Design Co. Ltd.Wuhan430223HubeiChina College of Geophysics and Oil Resources Yangtze UniversityWuhan430100HubeiChina

There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable *** a few of them are quantitative,especially in the size and shape of the *** paper first established the finite element model of the strain of buried pipeline crossing a fault which effected by the size and shape of the *** it obtained new soil spring stiffness which considered different buried depth,bottom width of trench,trench slope and elastic modulus of *** mechanical analysis model of pipeline is established,and the limit state equation of pipeline is *** reliability and sensitivity of the natural gas pipeline under fault action are analysed by a Monte Carlo method,and the error and accuracy are *** the pipeline is under tension,the sensitivity from large to small is buried depth,sand friction angle,pipe diameter,pipeline displacement,trench bottom width,trench depth,clay cohesion,trench slope and clay friction angle;when the pipeline is under pressure,the trench depth and clay cohesion have great *** findings of this study provide a reference for pipeline design and safety evaluation under fault action.

关键词： Trench parameters Natural gas pipeline Fault Soil-pipeline interaction Soil spring stiffness

来源：

维普期刊数据库

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

Accelerated kinetics of alkaline hydrogen evolution/oxidation reactions on dispersed ruthenium sites through N and S dual coordination

引用

Science China Chemistry 2022年第3期65卷 611-618页

作者： zhen Zhang Liwen Ni Haijun Liu Zhi-Liang zhao xiao-Zi Yuan Hui Li School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Materials Science and Engineering Shenzhen Key Laboratory of Hydrogen EnergySouthern University of Science and TechnologyShenzhen 518055China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Research Center of Energy Mining and EnvironmentNational Research Council Canada4250 Wesbrook MallVancouver V6T1W5Canada

Efficient,robust and cost-effective electrocatalysts that catalyze hydrogen evolution/oxidation reaction(HER/HOR)in alkaline media are highly ***,single-atom catalysts(SACs)have emerged as new promising candidates;however,the rational design of supports and the optimization of coordination environment between supports and metal atoms are *** this work,we successfully fabricate atomically dispersed ruthenium(Ru)species,which are strongly coordinated by N and S dual heteroatoms on holey graphene(RuSA/NSG),as an excellent bifunctional catalyst for HER/*** alkaline media,the developed catalyst exhibits high catalytic performance with a low overpotential of 57.3 mV to drive a current density of 10 mA cm^(-1) for HER,and its mass activity is about 5.8 times higher than that of commercial Pt/C and Ru/C catalysts at an overpotential of 100 ***,considerable HOR performance of Ru SA/NSG is verified to be superior to Pt/C and Ru/***,X-ray-based spectroscopy measurements and density-functional theory calculations have confirmed that,compared with Ru–N_(4),the tailored Ru–N_(4)–S_(2) with nearby S dopants can act as more active centers to greatly accelerate the sluggish HER/HOR kinetics in alkaline *** present work provides a new atomic-level engineering strategy to modulate catalytic activities of SACs via the coordination design using dual heteroatoms on the carbon support.

关键词： single-atom catalyst ruthenium hydrogen evolution reaction hydrogen oxidation reaction density-functional theory

来源：

维普期刊数据库

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

Efficient homogenous catalysis of CO_(2) to generate cyclic carbonates by heterogenous and recyclable polypyrazoles

引用

Chinese Journal of Chemical Engineering 2022年第3期35卷 110-115页

作者： zhen Lu Jie He Bogeng Guo Yulai zhao Jingyu Cai Longqiang xiao Linxi Hou Department of Materials-Oriented Chemical Engineering School of Chemical EngineeringFuzhou UniversityFuzhou 350116China Qingyuan Innovation Laboratory Quanzhou 362801China Fujian Key Laboratory of Advanced Manufacturing Technology of Specialty Chemicals Fuzhou UniversityFuzhou 350116China

The cycloaddition between CO_(2)and epoxides to produce cyclic carbonate is an attractive and efficiency pathway for the utilization of CO_(2)as C1 *** development of catalyst to mediate cycloaddition between CO_(2)and epoxides at low temperature and pressure is still a ***,a series of polypyrazoles with glass transition temperature(T_(g))in the range of 42.3-52.5℃ were synthesized and served as catalyst to mediate the cycloaddition of CO_(2)and epoxides by the assistant of tetrabutylammonium *** catalytic behaviors of polypyrazole on the model cycloaddition of CO_(2)to epichlorohydrin,including the reaction parameters optimization and versatility were investigated in detail,and excellent yield(99.9%)and selectivity(99%)were obtained under the optimized reaction conditions of70℃ and 1.0 MPa for 6.0 ***,the polypyrazole acts as homogeneous catalyst during reaction(higher than T_(g)).And under room temperature,polypyrazoles can be easily separated and recovered,which is a promising feature of a heterogeneous ***,the reaction mechanism was *** DFT calculation suggested that the formation of hydrogen bond between pyrazole and epoxide greatly reduced the energy barrier,which play an important role in promoting CO_(2)cycloaddition.

关键词： Carbon dioxide CO_(2)conversion Cyclic carbonate Heterogeneous catalysis Polypyrazole

来源：

维普期刊数据库

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

Time-Dependent Analysis of High-Gain Triggering in Semi-insulating GaAs Photoconductive Switches

引用

Chinese Physics Letters 2001年第11期18卷 1479-1480页

作者： SHI Wei zhao Wei LIANG zhen-Xian SUN xiao-Wei Applied Physics Department Xi'an University of TechnologyXi'an 710048 State Key Laboratory of Transient Optics and Technology Xi'an 710068 School of Electrical Engineering Xi'an Jiaotong UniversityXi'an 710049 Division of Microelectronics Nanyang Technological UniversitySingapore 639798

The transient transport of photo-generated carriers and temporal variation of the built-in field, during triggering in semi-insulating GaAs photoconductive switches, have been investigated by using a special Monte Carlo particle simulator. It shows that the built-in field can exceed the intrinsic avalanche field of semi-insulating GaAs under certain optical and electrical conditions. In such a case, local breakdown ionization is considered to be responsible for the transition in GaAs high-gain switching. The optical and electrical triggering thresholds are calculated and the calculated values of optical and electrical thresholds and partial delay time are in agreement with the published experimental data.

关键词： breakdown optical electrical

来源：

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

Fabrication and Characterization of Nanopillar-Like HA Coating on Porous Ti6Al4V Scaffold by a Combination of Alkali–Acid-Heat and Hydrothermal Treatments

引用

Acta Metallurgica Sinica(English Letters) 2019年第9期32卷 1075-1088页

作者： Jun-Lei Li Shuai Wang Fang Cao xiao Lin xiao-Wei Wei zhen-Hua zhao xiao-Jie Dou Wei-Ting Yu Ke Yang De-Wei zhao Department of Orthopaedics Affiliated Zhongshan Hospital of Dalian UniversityDalian 116001China Orthopaedic Institute Medical CollegeSoochow UniversitySuzhou 215006China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Porous titanium scaffold with suitable porous architecture exhibits enormous potentials for bone defect ***,insufficient osteointegration and osteoinduction still remain to open as one of the major problems to achieve satisfactory therapeutic *** solve this problem,many studies have been carried out to improve the bioactivity of porous titanium scaff old by surface *** this study,porous Ti6Al4V scaff olds were fabricated using additive manufacturing *** architectures were built up based on a diamond pore structure ***–acid-heat(AH)treatment was applied to create a TiO2 layer on the porous Ti6Al4V scaff old(AH-porous Ti6Al4V).Subsequently,a hydrothermal treatment was employed to enable the formation of HA coating with nanopillar-like morphology on the alkali–acid-heat-treated surface(HT/AH-porous Ti6Al4V).The effects of surface modifications on apatite-forming ability,protein adsorption,cell attachment,cell proliferation and osteogenic gene expression were studied using apatite-forming ability test,protein adsorption assay and in vitro cell culture *** was found that the HT/AH-porous Ti6Al4V exhibited the highest apatite formation ability and best affinity to fibronectin and *** vitro studies indicated that the mesenchymal stem cells(MSCs)cultured on the HT/AH-porous Ti6Al4V presented improved adhesion and differentiation compared with the porous Ti6Al4V and AH-porous Ti6Al4V.

关键词： Additive manufacturing Biomaterials Porous titanium scaffold HA coating

来源：

维普期刊数据库

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

A Preliminary study on the seismic conceptual design

引用

Earthquake Engineering and Engineering Vibration 2014年第S1期13卷 183-188页

作者： zhao zhen Xie Lili Institute of Engineering Mechanics China Earthquake Administration Key Laboratory of Earthquake Engineering and Engineering Vibration China Earthquake Administration School of Civil Engineering Harbin Institute of Technology

The seismic conceptual design is an essential part of seismic design codes. It points out that the term 'seismic conceptual design' should imply three aspects,i.e.,the given concept itself,the specific provisions related to the given concept and the designing following the provisions. Seismic conceptual design can be classified into two categories: the strict or traditional seismic conceptual design and the generalized seismic conceptual design. The authors are trying to define for both conceptual designs their connotations and study their characteristics,in particular,the differences between them. Authors emphasize that both conceptual designs sound very close,however,their differences are apparent. The strict conceptual designs are usually worked out directly from engineering practice and/or lessons learnt from earthquake damage,while the generalized conceptual designs are resulted in a series of visions aiming to realize the general objectives of the seismic codes. The strict conceptual designs,(traditional conceptual designs) are indispensable elements of seismic codes in assuring designed structures safer and the generalized conceptual designs are playing key roles in directing to a more advanced and effective seismic codes.

关键词： Conceptual design Earthquakes

来源：

维普期刊数据库

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

Surface treatments of CdGeAs2 single crystals

引用

Rare Metals 2019年第7期38卷 683-688页

作者： Wei Huang Bei-Jun zhao Shi-Fu Zhu Zhi-Yu He Bao-Jun Chen zhen zhen Yun-xiao Pu College of Materials Science and Engineering Sichuan University

The performances of second harmonic gen eration (SHG) and optical parametric oscillator (OPO) in CdGeAs2 crystal are strongly influenced by surface quality. In this paper, the surfaces of samples were treated by mechanical polishing (MP), chemical polishing (CP), chemical-mechanical polishing (CMP) and CP following CMP closely (CMP + CP). Then, the surface state was characterized by optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM measurements show that an ultra-smooth surface is achieved after CMP + CP treatment and the roughness value is 0.98 nm. Meanwhile, the roughness of the surfaces treated by MP, CP and CMP are 4.53, 2.83 and 1.38 nm, respectively. By XRD rocking curves, the diffraction peak which belongs to the wafer treated by CMP + CP is the highest in intensity and best symmetrical in shape. XPS analysis indicates that Ge4+ proportions of GeO2 in total Ge content of CdGeAs2 wafers' surface after MP, CP, CMP and CMP + CP treatment are 27.6%, 42.8%, 6.1% and 30.3%, respectively.

关键词： CdGeAs2 single crystal Surface treatments Surface roughness

来源：

维普期刊数据库

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：