检索结果-南通市图书馆

Spatial variations of tidal water level and their impact on the exposure patterns of tidal land on the central Jiangsu coast

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2010年第1期29卷 79-87页

作者： WANG Zhenyan GAO Shu HUANG Haijun key laboratory of Marine Geology and Environment Chinese Academy of Sciences Qingdao 266071 China Graduate School Chinese Academy of Sciences Beijing 100039 China MOE key laboratory for Coast and Island Development Nanjing University Nanjing 210093China

The exposed area of intertidal zone varies with tidal water level changes, If intercomparisons of satellite images are adopted as a method to determine geomorphological changes of the intertidal zone in response to accretion or erosion processes, then the effect of water level variations must be evaluated. In this study, two Landsat TM images overpassing the central Jiangsu coastal waters on 2 January and 7 March 2002, respectively, were treated by the changing detection analysis using Image Differencing and Post-classification Comparison. The simultaneous tide level data from four tide gauge stations along the coast were used for displaying the spatial variations of water levels and determining the elevations of waterlines. The results show that the spatial variations of water levels are highly significant in the central Jiangsu coastal waters. The huge differences of tidal land exposure patterns between the two imaging times are related mainly to the spatial variations of tidal water levels, which are controlled by the differences in tidal phases for different imaging times and the spatial variations of water level over the study area at each imaging time. Under complex tidal conditions, e.g., those of the central Jiangsu coastal waters, the tide-surge model should be used to eliminate effectively the effects of water level variations on remote sensing interpretation of geomorphological changes in the intertidal zone.

关键词： waterline water level variations exposure patterns central Jiangsu coast remote sensing

Plastic deformation of nanocrystalline nickel

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2009年第8期52卷 2216-2221页

作者： WU XiaoLei State key laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, china State key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline (NC) Ni subject to cold rolling at liquid nitrogen temperature. The activation of grain-boundary-mediated-plasticity is evidenced in NC-Ni, including twinning and formation of stacking fault via partial dislocation slips from the grain boundary. The formation and storage of 60? full dislocations are observed inside NC-grains. The grain/twin boundaries act as the barriers of dislocation slips, leading to dislocation pile-up, severe lattice distortion, and formation of sub-grain boundary. The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation. The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

关键词： nanocrystalline metal plastic deformation deformation twinning dislocation microstructure

Modeling of Air Temperature for Heat Exchange due to Vertical Turbulence and Horizontal Air Flow

在线全文

学校读者我要写书评

暂无评论

湖南大学学报（自然科学版） 2009年第S1期36卷 45-50页

作者： ZHANG Lei,MENG Qing-lin(State key laboratory of Subtropical Building Science,South china University of Technology,Guangzhou,Guangdong 510640,china) State key laboratory of Subtropical Building Science South China University of Technology Guangzhou 510640 China

In order to calculate the air temperature of the near surface layer in urban environment,the surface layer air was divided into several layers in the vertical direction,and some energy balance equations were developed for each air layer,in which the heat exchange due to vertical turbulence and horizontal air flow was taken into ***,the vertical temperature distribution of the surface layer air was obtained through the coupled calculation using the energy balance equations of underlying surfaces and building ***,the measured air temperatures in a small area(with a horizontal scale of less than 500 m)and a large area(with a horizontal scale of more than 1 000 m)in Guangzhou in summer were used to validate the proposed *** calculated results agree well with the measured ones,with a maximum relative error of 4.18%.It is thus concluded that the proposed model is a high-accuracy method to theoretically analyze the urban heat island and the thermal environment.

关键词： turbulent heat exchange urban thermal environment near surface layer air temperature calculation model

Effect of Thermal Fatigue Loading on Tensile Behavior of H13 Die Steel with Biomimetic Surface

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2010年第4期7卷 390-396页

作者： Zhihui Zhang~1,Luquan Ren~1,Hong Zhou~2,Zhiwu Han~1,Xin Tong~3,Yu Zhao~1,Li Chen~1 1.key laboratory of Bionic Engineering (Ministry of Education,china),Jilin University,Changchun 130022,P.R.china 2.key laboratory of Automobile Materials (Ministry of Education,china),Jilin University,Changchun 130022,P.R.china 3.The Department of Materials Surface Engineering,Guangzhou Research Institute of Non-Ferrous Metals,Guangzhou 510651,P.R.china [a] key laboratory of Bionic Engineering (Ministry of Education China) Jilin University Changchun 130022 P. R. China [b] Key Laboratory of Automobile Materials (Ministry of Education China) Jilin University Changchun 130022 P. R. China [c] The Department of Materials Surface Engineering Guangzhou Research Institute of Non-Ferrous Metals Guangzhou 510651 P. R. China

Biomimetic surface is an effective ways to promote the performance grade and applied range of materials without alteringtheir *** improved properties such as resisting fatigue,enduring wear,etc,have been achieved by applyingbiomimetic morphology or structure to some engineering material *** this paper,aiming to reveal the relationshipbetween thermal cracking behavior and mechanical properties of engineering materials with biomimetic surface,biomimeticspecimens were fabricated using laser technique by imitating the heterogeneous structure on the surface of plant *** of thermal fatigue cycling on the tensile properties of H13 die steel specimens with different surfaces (several types ofbiomimetic surfaces and a smooth surface) was compared and *** a result,due to the coupling effects of themorphological features on the surface and the microstructure characteristics within unit zone,these specimens with biomimeticsurface exhibit remarkably enhanced Ultimate Tensile Strength (UTS) and 0.2% Yield Strength (YS) compared with referencespecimens while corresponding ductility remains largely unaffected even heightened,whether the thermal fatigue loads or *** relative mechanisms leading to these improvements have been discussed.

关键词： biomimetic surface coupling thermal fatigue tensile property H13 steel

Synthesis of superheavy nuclei with ^(238)U target

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10期52卷 1482-1488页

作者： LIU ZuHua1,3 & BAO JingDong2,4 1 key laboratory of Beam Technology and Material Modification of Ministry of Education,Beijing Normal University,Beijing 100875,china 2 Department of Physics,Beijing Normal University,Beijing 100875,china 3 china Institute of Atomic Energy,Beijing 102413,china 4 Center of Theoretical Nuclear Physics,National laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,china key laboratory of Beam Technology and Material Modification of Ministry of Education Beijing Normal University Beijing 100875 China Department of Physics Beijing Normal University Beijing 100875 China china Institute of Atomic Energy Beijing 102413 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically *** results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z *** cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

关键词： superheavy nuclei fusion reaction cross section 238U target

Possible mechanism of the effect of convection over Asian-Australian “land bridge” on the East Asian summer monsoon onset

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第11期49卷 1223-1232页

作者： HE Jinhai1, WEN Min2, DING Yihui3 & ZHANG Renhe2 1. Jiangsu key laboratory of Meteorological Disaster (KLME), Nanjing Institute of Meteorology, Nanjing University of Informa- tion Science and Technology, Nanjing 210044, china 2. State key laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological Sciences, Beijing 100081, china 3. National Climate Center, Chinese Meteorological Administration, Beijing 100081, china 1. Jiangsu key laboratory of Meteorological Disaster (KLME) Nanjing Institute of Meteorology Nanjing University of Information Science and Technology Nanjing 210044 China 2. State key laboratory of Severe Weather (LaSW) Chinese Academy of Meteorological Sciences Beijing 100081 China 3. National Climate Center Chinese Meteorological Administration Beijing 100081 China

The Asian-Australian “land bridge” is an area with the most vigorous convection in Asian monsoon region in boreal spring, where the onset and march of convection are well associated with the onset of East Asian summer monsoon. The convection occurs over Indo-china Peninsula as early as mid-April, which exerts critical impact on the evolution of monsoon circulation. Before mid-April there are primarily sensible heatings to the atmosphere over Indo-china Peninsula and Indian Peninsula, so the apparent heating ratios over them decrease with height. However, after mid-April it changes into latent heating over Indo-china Peninsula due to the onset of convection, and the apparent heating ratio increases with height in mid- and lower troposphere. The vertical distribution of heating ratio and its differences between Indo-china Peninsula and Indian Peninsula are the key factors leading to the splitting of boreal subtropical high belt over the Bay of Bengal. Such mechanism is strongly supported by the fact that the evolution of the vertical heating ratio gradient above Indo-china Peninsula leads that of 850 hPa vorticity over the Bay of Bengal. Convections over Indo-china Peninsula and its surrounding areas further increase after the splitting. Since then, there is a positive feedback lying among the convective heating, the eastward retreat of the subtropical high and the march of monsoon, which is a possible mechanism of the advance of summer monsoon and convection from Indo-china Peninsula to South china Sea.

关键词： Asian-Australian 'land bridge', tropical convection, Indo-china Peninsula, the splitting of boreal subtropical high belt, East Asian summer monsoon onset.

Effect of Powder Particle Size on the Properties and Microstructure of Ti(C,N)-Based Cermet

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2001年第1期20卷 47-51页

作者： Yong Zheng, Weihao Xiong (key State laboratory of Die Technology, Huazhong University of Science and Technology, Wuhan 430074, china) Huazhong Univ Sci & Technol Key State Lab Die Technol Wuhan 430074 Peoples R China

The influence of raw powder particle size on the properties and microstructures of Ti (C, N)-based cermets has been studied. The conclusions are as follows: The microstructures of cermets were composed of two kinds of grains, the one with black cores surrounded by obvious rim structures, and the other whose cores were white with unconspicuous rim structures and adhesive phase. In the cermet made from fine powders, the amount of grains with white cores was much more than that in cermet made from coarse powders. In addition, their properties were also much better.

关键词： Ti(C, N)-based cermet powder particle size property microstructure

Density functional theory study on the structural and electronic properties of Ag-adsorbed (MgO)_n clusters

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5期52卷 734-741页

作者： GE GuiXian1, JING Qun1 & LUO YouHua2,3 1 key laboratory of Ecophysics and Department of Physics, Normal College, Shihezi University, Shihezi 832003, china 2 School of Science, East china University of Science and Technology, Shanghai 200237, china 3 Institute for Theoretical Physics, Henan University, Kaifeng 475004, china key laboratory of Ecophysics and Department of Physics Normal College Shihezi University Shihezi 832003 China School of Science East China University of Science and Technology Shanghai 200237 China Institute for Theoretical Physics Henan University Kaifeng 475004 China

Equilibrium geometries, charge distributions, stabilities and electronic properties of the Ag-adsorbed (MgO)n (n = 1-8) clusters have been investigated by density functional theory (DFT) with generalized gradient approximation (GGA) for exchange-correlation functional. The results show that hollow site is energetically preferred for n≥4, and the incoming Ag atoms tend to cluster on the existing Ag cluster. The Mulliken populations indicate that the interaction between the Ag atom and Magnesia clusters is mainly induced by a weak atomic polarization. The adsorbed Ag atom only causes charge redistributions of the atoms near itself. The effect of the adsorbed Ag atom on the bonding natures and structural features of Magnesia clusters is minor. Furthermore, the investigations on the first energy difference, fragmentation energies and electron affinities show that the Ag(MgO)4 and Ag(MgO)6 are the most stable among studied clusters.

关键词： Ag (MgO)_n clusters geometries electronic properties

Multiparty quantum secret sharing of classical and quantum messages

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( key laboratory for Quantum Information and Measurements, and Department of Physics, Tsinghua University, Beijing 100084, china key laboratory of Beam Technology and Material Modification, MOE, Institute of Low Energy Nuclear Physics, and Department of Material Science and Engineering, Beijing Normal University, Beijing 100875, china Beijing Radiation Center, Beijing 100875, china key laboratory for Atomic and Molecular Nano-Sciences, Tsinghua University, Beijing 100084, china) [a]key laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing China [b]key laboratory of Beam Technology and Material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing China [c]Beijing Radiation Center Beijing China [d]key laboratory for Atomic and Molecular Nano-Sciences Tsinghua University Beijing China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.