检索结果-南通市图书馆

Progress in Natural Science:Materials International 2008年第6期18卷 661-664页

作者： Bo Zhoua,Zhisong Xiaoa,*,Anping Huang a,Lu Yan a,Fang Zhu a,Jinliang Wang a,Penggang Yin b,Hao Wang c aDepartment of Physics,School of Science,Beihang University,beijing 100083,china bSchool of Materials Science and Engineering,Beihang University,beijing 100083,china cFaculty of Physics and Electronics,Hubei University,Wuhan 430062,china Department of Physics School of Science Beihang University Beijing 100083 China School of Materials Science and Engineering Beihang University Beijing 100083 China Faculty of Physics and Electronics Hubei University Wuhan 430062 China

Er-Tm codoped amorphous aluminum oxide(a-Al2O3)thin films have been prepared by an alternative pulsed laser *** phase structure and the surface of the deposited thin films were characterized by the X-ray diraction(XRD)and scanning electron microscopy(SEM),*** photoluminescence(PL)in the region of 350-900 nm was observed when pumped at 325 nm,and the PL performance has been improved by modifying the Tm3 +*** the increasing of[Tm]/[Er]concentra-tion ratio,the intensity of emission of 382 nm and 500 nm bands was improved eectively while that of 765 nm band increased *** results suggest that the resonant energy transfer and cross relaxation between Tm3 +and Er 3+play an important role in the evolution of the luminescent response.

关键词： Tm Er Concentration Photoluminescence Energy transfer

Slope Reinforcement for Housing in Three Gorges Reservoir Area

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2011年第2期8卷 314-320页

作者： WU Faquan LUO Yuanhua CHANG Zhonghua Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Office of Three Gorges Project Construction Committee the State Council of China Beijing 100038 China

The Three Gorges Project of the Yangtze River is the largest hydropower-complex project under construction in the world. Under the largescale relocation projects, 2874 engineered slopes are formed along with the construction of new towns. In this paper, the cutting slopes are mainly soil slopes and rock slopes. Soil slopes include residual soil slopes, colluvial accumulation slopes, swelling soil slopes, and artificial earth fill slopes, etc. Rock slopes include blocky structure rock slopes, layer structure rock slopes, and clastic structure rock slopes, etc. Varied protection measures have been used for slope protection in the reservoir area including shotcrete concrete-anchor bars, frame beams, retaining walls, slope stabilizing piles, sheet-pile walls, anchorage anti-shear tunnels, flexible protection grids, and drainage, etc. Besides, slope deformation monitoring systems have been set up to monitor deformation failure and the stability state of slopes. The protection measures have guaranteed slope safety and maintained a harmony with the urban environment and surrounding landscape.

关键词： Slope reinforcement Housing for resettlement Three Gorges Reservoir

Spatially discontinuous ionization phenomenon in inhomogeneous soil

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第4期53卷 918-921页

作者： ZHANG BaoPing,HE JinLiang & ZENG Rong State Key Lab of Power Systems,Department of Electrical Engineering,Tsinghua University,beijing 100084,china State Key Lab of Power Systems Department of Electrical Engineering Tsinghua University Beijing China

By using X-ray film imaging technology,a phenomenon of discontinuous ionization was observed in the inhomogeneous soil around the grounding electrode on which a surge voltage was applied.A simplified two-phase solid-gas model was built to study the electric field distribution in the soil to explain the discontinuous ionization *** showed the differences of the dielectric properties,the shapes and sizes of soil particles can cause discontinuous ionization in the soil.

关键词： discontinuous ionization inhomogeneous soil X-ray film porous medium electric field distribution

Improvement on the Neural Algorithm for Communication Network Partitioning Design

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 1997年第1期4卷 59-61页

作者： Chen Xiao and Ruan Chuangai (Department of Information Engineering,beijing University of Posts and Telecommunications ,beijing 100088,P.R china)

In paoer ,an algorithn based on neural network was propsced for the communication metwork k-partitioning *** paper simplifies the energy function,so that the optimal solution can be got nore easily,Computer simulati... 详细信息

关键词： graph k-partitioning neural network energy function

中国塑料管道市场分析报告——钢增强塑料管道市场前景

在线全文

学校读者我要写书评

暂无评论

塑料工业 2011年第11期39卷 118-147页

作者： (beijing Plastic Industry Association,beijing 100000,china) 北京塑料工业协会

介绍了近几年国内外塑料管道市场发展现状及趋势;同时分析了国内管道行业的发展特点;提出了我国塑料管道行业目前存在的主要问题;对应用领域塑料管道产品的生产和应用情况进行了阐述;分析了钢增强塑料管道现有技术水平和良好的市场前景。

关键词：塑料管道钢增强塑料管道发展趋势应用

Effect of Finish Rolling Temperature on Microstructure and Mechanical Properties of High Grade Pipeline Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第S1期18卷 625-628页

作者： TANG Xing-chang,KANG Yong-lin,BO Yan-yan (School of Materials Science and Engineering,State Key Laboratory for Advanced Metals and Materials,University of Science and Technology beijing,beijing 100083,china) Univ Sci & Technol beijing State Key Lab Adv Met & Mat Sch Mat Sci & Engn Beijing 100083 Peoples R China

The correlation among finish rolling temperature (FRT),microstructure and mechanical property of the high grade pipeline steel was investigated in this *** microstructure of the steels with different finish rolling temperatures was observed with scanning electronic microscope (SEM) and transmission electronic microscope (TEM).The martensite/austenite (M/A) islands distribution was fixed by colour metallography,and the mechanical properties of the steels were tested with quasi-static tensile testing *** result shows that the fraction of M/A island increased with the finish rolling temperature decreasing,and when the finish rolling temperature is 800℃,the mechanical properties are the best.

关键词： high grade pipeline steel finish rolling temperature martensite/austenite island

UNIQUENESS OF OPTIMAL QUADRATURE FORMULAS FOR W_1~m AND THE FUNDAMENTAL THEOREM OF ALGEBRA FOR PERIODIC MONOSPLINES

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1990年第4期11卷 426-437页

作者：黄达人房艮孙 Department of Mathematics Zhejiang UniversityHangzhouZhejianghina. Department of Mathematics Beijing Normal UniversityBeijingChina.

This paper proves that the optimal quadrature formulas of type（r1,…rn） for Wm1 isunique,and the extremal function is characterized by its oscillatory *** theother hand,the fundamental theorem of algebra for periodi... 详细信息

关键词： quadrature oscillatory algebra formulas uniqueness whenever polynomial lemma 七势 isola

An analysis of the wide area differential method of geostationary orbit satellites

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 310-314页

作者： CAI ChengLin1,2,3?, LI XiaoHui1 & WU HaiTao1 1 National Time Service center, Chinese Academy of Sciences, Lintong 710600, china 2 Hunan Institute of Humanities, Science and Technology, Loudi 417000, china 3 Graduate University of Chinese Academy of Sciences, beijing 100049, china National Time Service center Chinese Academy of Sciences Lintong China Hunan Institute of Humanities Science and Technology Loudi China Graduate University of Chinese Academy of Sciences Beijing China

This work aims to obtain a wide area differential method for geostationary orbit (GEO) constellation. A comparison between the dilution of precision (DOP) of four-dimensional (4D) calculation including sa- tellite clock errors and ephemeris errors and that of three-dimensional (3D) calculation only including ephemeris errors with the inverse positioning theory of GPS shows the conclusion that all the 3D PDOPs are greatly reduced. Based on this, a basic idea of correcting satellite clock errors and ephem- eris errors apart is put forward, and moreover, a specific method of separation is proposed. Satellite clock errors are separated in a master station with time synchronization, and all the remaining pseu- do-range errors after the satellite clock errors have been deducted are used to work out ephemeris corrections of all GEO satellites. By a comparative analysis of user positioning accuracy before and after differential, the wide area differential method is verified to be quite valid for GEO constellation.

关键词： geostationary orbitsatellite dilution of precision satellite ephemeris errors satellite clock errors wide area differential method

Ab initio theoretical studies on N_(28),B_4N_(24),B_(12)N_(16), and B_(16)N_(12) with T_d symmetry

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1996年第6期14卷 490-496页

作者： JIANG, Xin-Tian HU, Xu-Guang LI, Qian-Shu Department of Chemistry, Shaanxi Teachers University, Xi’an, Shanxi 710062, china Institute of Theoretical Chemistry, National Laboratory of Theoretical and Computational Chemistry, JilinUniversity, Changchun, Jilin 130023, chinaSchool of Chemical Engineering and Materials Science, beijing Institute of Technology, beijing 100081,china Department of Chemistry Shaanxi Teachers University Xi'an Shanxi 710062 China Institute of Theoretical Chemistry National Laboratory of Theoretical and Computational Chemistry Jilin University Changchun Jilin 130023 China School of Chemical Engineering and Materials Science Beijing Institute of Technology Beijing 100081 China

Structures, energies and vibrational frequencies have been calculated for hollow cage clusters N28, B4N24, B12N16, and B16N12 with Td symmetry using ab initio quantum mechanical methods at the RHF/3-21G level. Each species is predicted to be both chemically and kinetically stable. Skeletal polyhedrons of all considered boron nitride hollow cage clusters are constructed from 5- and 6-membered rings.

关键词： Nitrogen cluster boron nitride cluster ab initio molecular orbital theory fullerene

A Certain Kind of Non-Degenerate Solvable Lie Algebra on C

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 1998年第2期5卷 60-64页

作者： Mo Jiao (Department of Basic Science. beijing University of Posts and Telecommunications, beijing, 100876, P. R. china)

This paper deals with the non-degenerate solvable Lie algebra. They are divided into the direct sum of root subspaces under certain conditions. Some properties of these subspaces are shown in this paper.

关键词： ideal direct sum root subspace