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Wavelet-based Mixed-Resolution Coding Approach Incorporating with SPT for the Stereo Image

Journal of Systems Engineering and Electronics 2001年第3期12卷 39-44页

作者： Xu, C. zhang, z. An, P. Communication School Shanghai University Shanghai 200072 China

With the advances of display technology, three-dimensional(3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pairs, data compression algorithms should be employed to represent stereo pairs efficiently. The proposed techniques generally use block-based disparity compensation. In order to get the higher compression ratio, this paper employs the wavelet-based mixed-resolution coding technique to incorporate with SPT-based disparity-compensation to compress the stereo image data. The mixed-resolution coding is a perceptually justified technique that is achieved by presenting one eye with a low-resolution image and the other with a high-resolution image. Psychophysical experiments show that the stereo image pairs with one high-resolution image and one low-resolution image provide almost the same stereo depth to that of a stereo image with two high-resolution images. by combining the mixed-resolution coding and SPT-based disparity-compensation techniques, one reference (left) high-resolution image can be compressed by a hierarchical wavelet transform followed by vector quantization and Huffman encoder. After two level wavelet decompositions, for the low-resolution right image and low-resolution left image, subspace projection technique using the fixed block size disparity compensation estimation is used. At the decoder, the low-resolution right subimage is estimated using the disparity from the low-resolution left subimage. A full-size reconstruction is obtained by upsampling a factor of 4 and reconstructing with the synthesis low pass filter. Finally, experimental results are presented, which show that our scheme achieves a PSNR gain (about 0.92db) as compared to the current block-based disparity compensation coding techniques.

关键词： Data reduction Decoding Image coding Image compression Image reconstruction Imaging techniques Motion compensation Motion estimation Optical resolving power Projection systems Stereo vision Wavelet transforms

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MECHANICAL PROPERTIES OF LONGITUDINAL SUbMERGED ARC WELDED STEEL PIPES USED FOR GAS PIPELINE OF OFFSHORE OIL

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Acta Metallurgica Sinica(English Letters) 2008年第2期21卷 85-93页

作者： z.z. Yang W. Tian Q.R. Ma Y.L. Li J.K. Li J.z. Gao H.b. zhang Y.H. Yang Tubular Goods Research Center of CNPC Xi＇an 710065 China Xiran Aerotechnical College Xi＇an 710077 China

Since the development of offshore oil and gas, increased submarine oil and gas pipelines were installed. All the early steel pipes of submarine pipelines depended on importing because of the strict requirements of comprehensive properties, such as, anti-corrosion, resistance to pressure and so on. To research and develop domes- tic steel pipes used for the submarine pipeline, the Longitudinal-seam Submerged Arc Welded （LSAW） pipes were made of steel plates cut from leveled hot rolled coils by both the JCOE and UOE （the forming process in which the plate like the letter “J”, “C”, “0” or “U” shape, then expansion） forming processes. Furthermore, the mechanical properties of the pipe base metal and weld metal were tested, and the results were in accordance with the corresponding pipe specification API SPEC 5L or DNV- OS-FI01, which showed that domestic LSAW pipes could be used for submarine oil and gas pipelines.

关键词： Mechanical properties Offshore oil and gas Longitudinal-seamsubmerged arc welded pipe (LSA W) Pipeline JCOE formingprocess UOE forming process

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First-principles study of the electronic structure of a superstoichiometric rare earth dihydride GdH2.25

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Journal of Rare Earths 2016年第1期34卷 66-70页

作者： z.ayat a.boukraa b.daoudi Univ Ouargla Fac. Des Mathematiques et des Sciences de la Matidre Lab. Developpement des energies nouvelles et renouvelables dans les zones arides et sahariennes Ouargla 30000 Algeria

We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linearized augmented plane wave method （FP-LAPW） approach within the density functional theory （DFT） in the generalized gradient approximation （GGA） and local density approximation （LDA） as implemented in the WIEN2k simulation code at 0 K. The equilibrium properties were determined, the density of states, electronic density and the energy band structures were studied in details. It was concluded that the GGA optimized lattice parameter agreed much better with the experimental findings than the LDA one, The non negligible electronic density of states at the Fermi level confirmed that the GdH2.25 had a metallic character. The Fermi energy EF fell at a level where most of the states were rare-earth 5d-eg conduction states while negligible contributions of both interstitial （tetrahedral and octahedral） H s-states were observed near EF, From electronic density, the bonding between Gd and tetrahedral H atoms was of prominent covalency, while was ionic between Gd and octahedral H atoms.

关键词： rare-earth dihydrides GdU2.25 density functional theory ab initio calculations WIEN2k

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The role of melt cooling rate on the interface between 18R and Mg matrix in Mg_(97)zn_(1)Y_(2) alloys

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Journal of Magnesium and Alloys 2023年第8期11卷 2883-2890页

作者： Q.Q.Jin X.H.Shao J.M.Li z.z.Peng M.Lv b.zhang Y.M.Li X.L.Ma Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Hebei University of Science and TechnologyShijiazhuangHebei 050018China

The role of melt cooling rate on the interface morphology and dislocation configuration between 18R long-period stacking ordered(LPSO)structure and Mg matrix in Mg_(97)zn_(1)Y_(2)(at.%)alloys was investigated by atomic-scale HAADF-STEM *** 18R/Mg interface is step-like both in the near-equilibrium alloy and non-equilibrium *** cooling rate makes the step size more regular and *** 54R structure can be observed at the interface in the near-equilibrium alloy,and the dislocations are highly ordered.54R and 54R′structure sandwiched by b1 and b2+b3 dislocation arrays,and new dislocation configuration can be detected at the interface in the non-equilibrium alloy,but the dislocations are less ordered.18R/Mg interface containing 54R or 54R′in equilibrium width,parallel to the(010)plane,should be most stable based on elastic *** segregation of solute atoms and its strong interaction with dislocations dominate the LPSO/Mg interface via diffusion-displacive transformation.

关键词： Magnesium alloys Long-period stacking ordered phases Dislocations Interface structure

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INVESTIGATION ON THE DENSITY UNIFORMITY OF PRESSED PARTS bY LOW-VOLTAGE ELECTROMAGNETIC COMPACTION

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 805-811页

作者： S.Y.Huang z.H.Meng Y.C.Li b.zhang W.Ouyang HarbinInstituteofTechnology Harbin150001China／／WuhanUniversityofTechnologyWuhan430070China WuhanUniversityofTechnology Wuhan430070China

Powder metallurgy is an efficient approach to fabricate varieties of high performance structure materials, function materials and special materials working under limited conditions. Research and development of new efficient technology to form high-density, high-performance and net shape parts is a key to widen application and development of powder materials. Recently, the low-voltage electromagnetic compaction (EMC) has been used by present authors to compacted copper, tin, aluminum powders and the products with 99% relative density have been acquired. In this work, the research has been extended to investigation on the density uniformity of pressed parts. The analysis results show that the density of the part compacted by low-voltage EMC decreases gradually in press direction as static compaction. but it is higher and more homogeneous. The density of the top part increases gradually from the center to the outer, which is just reversal of the bottom part. In some extent, the higher the discharging voltage is, the higher the density is and the more homogeneous the distribution is. In addition, repetitive compaction can improve the density of powder parts and the distribution uniformity.

关键词： powder low-voltage electromagnetic compaction density uniformity density distribution

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Influence of plasma condition on carbon nanotube growth by rf-PECVD

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Nano-Micro Letters 2010年第1期2卷 37-41页

作者： Y.H.Man z.C.Li z.J.zhang Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University

Carbon nanotubes(CNTs)have been synthesized from Ar-CH_4 mixtures using rf-plasma enhanced chemical vapor deposition(rf-PECVD)at *** gases such as H_2 and NH_3 were found unnecessary for carbon nanotube formation compared to thermal *** relationship between the growth of CNTs and the plasma condition in PECVD has been investigated by in situ self bias *** conditions were controlled by changing the interelectrode distance,rf power and the applied substrate negative *** increasing the interelectrode distance and rf power,the spatial density of CNTs was on a rise as a result of the increase in ions density and self *** the applied substrate negative bias increased,the spatial density of CNTs decreased possibly due to the positive ions over bombarding effect.

关键词： Carbon nanotube Plasma enhanced CVD Plasma condition

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High-Speed Friction Stir Welding of T6-Treated b4Cp/6061Al Composite

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 67-74页

作者： Y.z.Li Y.N.zan Q.z.Wang b.L.Xiao z.Y.Ma Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Science and Technology of China Shenyang 110016China

T6-treated 20 wt% b4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(FSW) with a threaded cermet pin. The macro-defect-free FSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. In the nugget zone(Nz) of the joints, the b4 C particles were broken up and uniformly redistributed. The Nz exhibited lower hardness than the base metal(bM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the bM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ~ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the Nz. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the Nz due to the kissing bond defects.

关键词： Metal-matrix composites Microstructures Mechanical properties Friction stir welding High-speed welding

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Fatigue behavior of CoCrFeMnNi high-entropy alloy under fully reversed cyclic deformation

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Journal of Materials Science & Technology 2019年第3期35卷 334-340页

作者： Y.z.Tian S.J.Sun H.R.Lin z.F.zhang Materials Fatigue and Fracture Division Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

bulk ultrafine-grained(UFG) CoCrFeMnNi high-entropy alloy(HEA) with fully recrystallized microstructure was processed by cold rolling and annealing treatment. The high-cycle fatigue behaviors of the UFG HEA and a coarse-grained(CG) counterpart were investigated under fully reversed cyclic *** fatigue strength of the UFG HEA can be significantly enhanced by refining the grain size. However,no grain coarsening was observed in the UFG HEA during fatigue tests. Mechanisms for the superior mechanical properties of the UFG HEA were explored.

关键词： High-entropy alloy(HEA) Ultrafine-grain(UFG) High-cycle fatigue Recrystallization Grain size Fatigue strength

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Structure and Magnetic Properties of S-doped Mn_3O_4/S Composited Nanoparticles and Mn_3O_4 Nanoparticles

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Journal of Materials Science & Technology 2011年第6期27卷 503-506页

作者： X. He z.H. Wang D.Y. Geng z.D. zhang Shenyang National Laboratory for Materials Science Institute of Metal Research and International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China

Composited nanoparticles,consisting of Mn3O4,S-doped Mn3O4 and S,were synthesized by co-precipitation reaction and Mn3O4 nanoparticles were then obtained after removing the pure S from the composited *** Mn3O4-type phase with larger lattice constant a was formed by doping *** fixed temperatures below Curie temperature（TC）,the magnetization of the S-doped Mn3O4/S composited nanoparticles was smaller than that of the Mn3O4 *** blocking temperature was 36.3 and 34.8 K for Sdoped Mn3O4/S composite and Mn3O4 nanoparticles,*** anisotropy field of S-doped Mn3O4/S composite was determined to be about 55.3 kOe.

关键词： Nanostructured materials Chemical synthesis X-ray diffraction Magnetic measurements

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STUDY OF THE INFLUENCE OF pH ON THE ELECTROCRYSTALLIzATION OF zINC

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 497-504页

作者： z. zhang W.H. Leng J. Q. zhang Department of Chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and Protection Institute of Metal Reseach The Chinese Academy of Sciences Shenyang 110016 China

The influence of pH value of the electrolyte solution on the zinc electroplating process was studied by means of cyclic voltammetry and chronoamperometry approaches. The results shown that, under this experimental conditions and at high overpotentials, the nucleation of zinc is instantaneous, and the nuclear densities N increase with the overpotentials. While at low potentials, no distinguished nucleation current can be observed. High pH promotes the deposition either by drifting the initial depositing potential positively, or by increasing the depositing current through the change of the total charge of the adsorption process Qads, i.e., thevstructure of electrochemical double layer.

关键词： zinc electroplating nucleation growth mechanism

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