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On the formation of couplet-style stratifications

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International Journal of Sediment research 2008年第1期23卷 85-91页

作者： Yu-Hai WANG1, Yan-Hong WANG2, and li-Qun TANG31 Ph.D., Engineer, Department of Sediment research, china Institute of Water Resources and Hydropower research, Chegongzhuangxilu 20, beijing 100044, china, 2 Ph.D., Engineer, Nanjing Hydraulic research Institute, Hujuguanlu 34, Nanjing 210024, china 3 Ph.D., Prof., Department of Sediment research, china Institute of Water Resources and Hydropower research, Chegongzhuangxilu 20, beijing 100044, china [a]Ph.D. Engineer Department of Sediment research china Institute of Water Resources and Hydropower research Chegongzhuangxilu 20 beijing 100044 china [b]Ph.D. Engineer Nanjing Hydraulic research Institute Hujuguanlu 34 Nanjing 210024 china [c]Ph.D. Prof. Department of Sediment research china Institute of Water Resources and Hydropower research Chegongzhuangxilu 20 beijing 100044 china

Couplet-style stratifications refer to the sedimentary sequences that consist of alternating coarse-grain-dominated bed and fine-grain-dominated bed, with or without a sandwiched middle-sized bed. The formation mechanism is complicated due to the interplays of varying driving force (s), sediment supply & transport and topographic configurations. This paper presents a comprehensive overview of such characteristic bedforms, which emerge during the transport and deposition of non-uniform sediments. The leading formative models include water-stage variation, gravel-overpassing process, superimposition of bedload sheets and avalanching process (inverse grading). Each process might produce similar or distinct sedimentological features with respect to grading, matrix content, grain attitude, bounding faces between beds and internal longitudinal/transverse geometry. The couplet-style stratified strata might play an active role in landscape evolution.

关键词： Couplet-style stratification Formative model Sedimentological features Landform

Migration and population genetics of the grain aphid Macrosiphum miscanti (Takahashi) in relation to the geographic distance and gene flow

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Progress in Natural Science:Materials International 2005年第11期15卷 1000-1004页

作者： GUO Wei, SHEN Zuorui, li Zhihong and GAO lingwang (College of Agronomy and Biotechnology, china Agricultural University, beijing 100094, china) College of Agronomy and Biotechnology China Agricultural University Beijing 100094 China

The population genetics of the grain aphid Macrosiphum miscanti (Takahashi) is analyzed by microsatellite markers. Samples collected from 15 locations in china have been examined at 5 polymorphic microsatellite loci. Overall, genetic diversity displays a relation between the migration and gene flow in the grain aphid; a free and frequent gene flow is found in the eastern populations, and gene isolation occurs in the two western populations, especially Datong population and Guiyang population. The natural barriers may present an insurmountable obstacle preventing gene flow and aphid migration. However, a spatial genetic differentiation between populations is correlated with their geographical separation, indicating the geographic differentiation may play an important role in shaping the genetic structure of M. miscanti populations. In addition, most populations of grain aphids are out of Hardy-Weinberg equilibrium and there is het-erozygote deficit. Based on F statistics, the average genetic differentiation among different geographical populations is relatively low. It seems that the long distance migration of the grain aphid may enhance gene flow and decrease genetic differentiation among different populations .

关键词： Macrosiphum miscanti microsatellite gene flow migration.

Characteristics of 5A90 Aluminum-lithium Alloy by YAG-MIG Hybrid Welding

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稀有金属材料与工程 2011年第S4期40卷 95-98页

作者： Xu Fei,Gong Shuili,Chen li,Yang Jing Science and Technology on Power Beam Processes Laboratory,AVIC beijing Aeronautical Manufacturing Technology research Institute,beijing 100024,china AVIC beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China

The characteristics of 5A90 Aluminum-lithium alloy by YAG laser and MIG arc hybrid welding (Hybrid welding) were *** with the laser beam welding (LBW),the hybrid welding could not only improve the weld appearance significantly,but also have better engineering *** obvious microstructure characteristics of joint by the hybrid welding are fine-grained layer near fusion-line and the equiaxed grain in most area of welded *** subgrains of the equiaxed grains,located in the weld center,tend to coarse from bottom to top of weld *** microhardness of welded seam by the hybrid welding (83.57HV0.2) is lower than that by LBW (95.65HV0.2),but the uniformity of the former is better than that of the *** ultimate strength and the elongations after fracture of the joint by the hybrid welding are lower than that by *** tensile fracture always occurs in HAZ or weld centerline,and the fractography presents mixture ***,if the combined mechanical properties of joint by the hybrid welding meet the operation requirements,it should be improved by reasonable artificial aging or heat treatment after welding,and it also should develop a better filler wire matched with the base metal.

关键词： Al-li alloy hybrid welding LBW microstructure tensile property

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

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Rare Metals 2010年第2期29卷 220-225页

作者： ZHANG Qian, ZHANG Boping, li Haitao, and SHANG Pengpeng School of Materials Science and Engineering, University of Science and Technology beijing, beijing 100083, china School of Materials Science and Engineering University of Science and Technology Beijing

Lead-free piezoelectric NaxK1-xNbO3（x = 0.3-0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2 *** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3 *** MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 122 pC/N, planar-mode electromechanical coupling coefficient kP of 28.6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 *** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 420°C and 200°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)

APF-GAN:Exploring asymmetric pre-training and fine-tuning strategy for conditional generative adversarial network

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Computational Visual Media 2024年第1期10卷 187-192页

作者： Yuxuan li lingfeng Yang Xiang li College of Computer Science Nankai UniversityTianjinChina School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjingChina

The use of generative adversarial network(GAN)-based models for the conditional generation of image semantic segmentation has shown promising results in recent ***,there are still some limitations,including limited diversity of image style,distortion of detailed texture,unbalanced color tone,and lengthy training *** address these issues,we propose an asymmetric pre-training and fine-tuning(APF)-GAN model.

关键词： tuning network asymmetric

Magnetic properties and structure of very thin permalloy films

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Journal of University of Science and Technology beijing 2004年第3期11卷 225-229页

作者： Guanghua Yu Haifeng li Tao Yang Fengwu Zhu Materials Science and Engineering School, University of Science and Technology beijing, beijing 100083, china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

In order to study the magnetic properties and structure of very thinpermalloy films, Ni_(81)Fe_(19) films of 12 nm in thickness were prepared by different instrumentsat an ultrahigh base vacuum and a lower base vacuum. The anisotropic magnetoresistance coefficients(ΔR/R) of Ni_(81)Fe_(19) (12 nm) films reached 1.6 % and 0.6 %, and the coercivities were 127 and334 A/m, respectively. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were usedto study the structure and surface chemical state. The experimental results show that the filmsprepared at the ultrahigh base vacuum have a smoother surface, a bigger grain size and a denserstructure with fewer defects than those prepared at the lower base vacuum.

关键词： NiFe film anisotropic magnetoresistance (AMR) coercivity structure

Microstructure and Deformation Mechanics of X100 line Pipe Steel

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Journal of Iron and Steel research International 2011年第S1期18卷 255-261页

作者： li Yang 1,2,MENG li 1,JI ling-kang 2,li He-lin 2 (1.School of Material Science and Egineering,University of Sceince and Technology beijing,beijing 100083,china 2.CNPC Tubular Goods research Institute,Xi’an 710065,china) Univ Sci & Technol beijing Sch Mat Sci & Egineering Beijing 100083 Peoples R China CNPC Tubular Goods Res Inst Xian 710065 Peoples R China

In present paper,microstructure is observed by means of OM,SEM,EBSD and TEM analysis on material obtained from X100 linepipe with wall thickness as 20.6mm and outside diameter as 1016mm diameter Grade *** study the deformation mechanics,microstructure transformation is also investigated on deformed specimens with different strain level as 0%,5% and 8%.Results show that X100 line pipe material consists mainly of acicular ferrite whose ratio in material reaches 64%,obvious cellular structures formed by tangled dislocation and M/A island distributed in acicular plates indicate abundant dislocation and substructure existed in *** is measured that line pipe steel has a much finer effective grain size as 2.07μm,which can results in a higher strength and toughness for line pipe *** analysis for Kikuchi Pattern reveals that the ratio of large-angle boundary is comparatively higher as 55%,implying that line pipe steel has a good *** is observed that the proportion of small-angle grain boundary increases greatly after material deformed,which consequently results in the increment of dislocation and sub-structure.

关键词： X100 line pipe acicular Ferrite M/A grain boundary misorientation

Microstructure and optical properties of sprayed γ-CuI thin films for CuInS_2 solar cells

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Rare Metals 2011年第1期30卷 22-27页

作者： YAN Youhua ZHOU Shaoxiong LU Zhichao li Zhengbang Advanced Technology ＆ Materials Co.Ltd. China Iron ＆ Steel Research Institute GroupBeijing 100081China

γ-CuI thin films were prepared by a spraying method using acetonitrile as a solvent,CuI and iodine as *** influences of substrate temperature on the structure,topography,and optical properties of CuI films were *** electron microscope（SEM） photos revealed that the shape and grain size of CuI grains were related to substrate temperature.X-ray diffraction results showed that substrate temperature affected the crystalline quality of CuI *** the substrate temperature was 110°C,CuI thin films showed γ-phase zinkblende structure with（111） preferred *** dimension of the globular CuI crystallite was approximately 35 nm,the energy band gap was 2.97 eV,the maximum transmittance was 87.3% in the part of the visible region,and the open circuit voltage was close to 380 *** opened a route for a cadmium-free buffer layer for CuInS2 solar cells.

关键词： solar cells thin films spraying microstructure optical properties

EFFECT OF Nb ON STRENGTHENING OF Fe-BASE SUPERALLOY AT INTERMEDIATE HIGH TEMPERATURES

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Acta Metallurgica Sinica(English Letters) 1993年第2期6卷 81-85页

作者： CHEN Guosheng WU Bohua ZHOU Lecheng li Yuqing research Institute of Daye Steel Works,Huangshi,china Engineer,research Institute of Daye Steel Works,Huangshi 435001,china research Inst of Die Steel Works Huangshi China

Because Nb accelerates the uniform distribution of MC phase and the grain refinement,as well as,increases the amount and stability of γ-phase,the tensile strength,ductility,stress rupture life and fatigue limit of Fe-30Ni-13Cr-1.2W-1.5Mo-2.5Ti-0.4AI superalloy at 650℃ can be improved with increase of Nb content up to 1.22 wt-%.The precipitation of small Laves phase particles dispersed along grain boundaries may be favourable to combined properties of the superalloy containing 1.22 wt-% *** will be worsened only that the pre- cipitation of Laves phase particles'dispersed along grain boundaries may be favourable for combined properties of the superalloy containing 1.22 wt-% *** will be worsened only that the precipitation of Laves phase is too more because of too high Nb content existhing.

关键词： Nb Fe-base superalloy strengthening