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Polynomial analysis of canopy spectra and biochemical component content inversion

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Science china Earth Sciences 2005年第10期48卷 1780-1791页

作者： YAN Chunyan1, LIU Qiang1, NIU Zheng1, WANG Jihua2. HUANG Wenjiang2.& LIU Liangyun 2.1. State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, china 2. National Engineering {2. Center for Information technology in Agriculture, Beijing 100089, china State Key Laboratory of Remote Sensing Science Jointly Sponsored by the institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing china National Engineering research Center for Information technology in Agriculture Beijing {2.

A polynomial expression model was developed in this paper to describe directional canopy spectra, and the decomposition of the polynomial expression was used as a tool for re-trieving biochemical component content from canopy multi-angle spectra. First, the basic formula of the polynomial expression was introduced and the physical meaning of its terms and coeffi-cients was discussed. Based on this analysis, a complete polynomial expression model and its decomposition method were given. By decomposing the canopy spectra simulated with SAILH model, it shows that the polynomial expression can not only fit well the canopy spectra, but also show the contribution of every order scattering to the whole reflectance. Taking the first scattering coefficients a10 and a01 for example, the test results show that the polynomial coefficients reflect very well the hot spot phenomenon and the effects of viewing angles, LAI and leaf inclination angle on canopy spectra. By coupling the polynomial expression with leaf model PROSPECT, a canopy biochemical component content inversion model was given. In the simulated test, the canopy multi-angle spectra were simulated by two different models, SAILH and 4-SCALE re-spectively, then the biochemical component content was retrieved by inverting the coupled polynomial expression + PROSPECT model. Results of the simulated test are promising, and when applying the algorithm to measured corn canopy multi-angle spectra, we also get relatively accurate chlorophyll content. It shows that the polynomial analysis provides a new method to get biochemical component content independent of any specific canopy model.

关键词： polynomial expression, canopy spectra, decomposition, biochemical component content, inversion.

Wear Performance of Laser Surface Hardened GCr15 Steel

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Journal of Wuhan University of technology(Materials Science) 2010年第1期25卷 84-88页

作者：雷声 School of Materials Science and Engineering Hefei University of Technology Department of electromechanical Engineering Anhui Institute of Architecture and Industry

In order to assess the new tribological properties of laser surface hardened GCr15 steel, the wear resistance between specimens treated with laser and those of conventionally hardened under dry sliding conditions was compared. The change of wear mechanisms in laser hardened GCr15 resulted in a distinct difference in wear rates. The results showed that quenched zones not only had sufficient depth of hardening and higher hardness, but had more retained austenite and finer carbides because of a higher degree of carbide dissolution. Laser surface hardened GCr15 steel specimens exhibited superior wear resistance to their conventionally hardened specimens due to the effects of the microstructure hardening, high hardness and toughness. The wear mechanism for both the laser quenched layer and conventionally hardened layer was highly similar, generally involving adhesive, material transfer, wear-induced oxidation and plowing. When conventionally hardened block specimens rubbed against the laser hardened specimens, the surface of conventionally hardened block specimens was polished. The microstructural thermal stability was increased after laser surface treatment.

关键词： laser hardening dry sliding conditions GCr15 steel wear mechanisms

Fabrication of sub-micro size PZT array and their ferroelectric properties

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Science china(Technological Sciences) 2006年第6期49卷 693-700页

作者： ZHAO Gaoyang1, ZHANG Weihua1, XU Guomin1, DENG Xiaocui1, JIANG Bailing1 & ZHAO Wei2.1. School of Materials Science and Engineering, Xi’an University of technology, Xi’an 710048, china 2. Xi’an {2. of Optics and Precision Mechanics of CAS, Xi’an 710048, china 1. School of Materials Science and Engineering Xi’an University of Technology Xi’an 710048 China 2. Xi’an institute of Optics and Precision Mechanics of CAS Xi’an 710048 China

The photosensitive PZT sols and their gel films were prepared by sol-gel process. Based on the photosensitivity of the PZT gel films, two-dimensional (2.) array of the PZT gel film was fabricated using twice-exposure of double-beam interference on the gel film. PZT gel films coated on ITO/quartz substrate were exposed to an interference fringe of 32. He-Cd laser beams, the substrate was rotated by 90° between the first and second irradiation steps. Island type periodic 2. array structures with a pitch of 1 μm and cell size of about 480 nm × 480 nm × 40 nm were formed after the irradiation, and followed by leaching with organic solvent, and then by heat treatment at 600°C for 15 min. The hysteresis loops of the cell in PZT array were in-situ measured by the online-operation of TF analyzer and atomic force microscope (AFM). The probe can be located on the locked cell of PZT array in the AFM image. The alternating voltage applied to the locked cell is supplied by the TF analyzer through the conductive coating probe, and then the test signal is fed back to the TF analyzer to obtain the hysteresis loop of the locked cell of array in the absence of top electrode. The results show that the sub-micro size PZT arrays prepared in this way are of polarization reversal characteristics with the alternating electric fields, thereby exhibiting obvious ferroelectricity.

关键词： PZT, ferroelectric films, photosensitivity, hysteresis loop.

Multi-scale sparse feature point correspondence by graph cuts

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Science china(Information Sciences) 2010年第6期53卷 1224-1232页

作者： ZHANG Hong 1 , MU Ying 1 , YOU YuHu 2.& LI JunWei 3 1 Image Processing Center, Beihang University, Beijing 100191, china 2.Beijing research {2. of special electromechanical technology, Beijing 100012. china 3 National Key Laboratory on Optical Features of Environment and Target, Beijing 100854, china 1. Image Processing Center Beihang University Beijing 100191 China2. Beijing Research Institute of Special Electromechanical Technology Beijing 100012 China3. National Key Laboratory on Optical Features of Environment and Target Beijing 100854 China

This paper presents a global stereo sparse matching technique based on graph cut theory to obtain accurate correspondence of stereo point pair in vision measurement ***, in order to obtain accurate location of feature points, a new multi-scale corner detection algorithm is proposed where wavelet coefficients are used to determine feature points by calculating an auto-correlation matrix.A sparse graph is constructed based on the feature points according to the graph cut ***, the feature point correspondence problem is transformed into a labeling problem in the sparse graph which can be solved by energy ***-scale analysis is utilized to improve the precision of matching *** was found that the use of sparse feature points in the construction of the graph can lead to both a simple graph structure and a reduced computational *** was also found that node labeling in the graph can be performed using fewer disparity values instead of all disparity *** experimental results show that the new global stereo sparse matching technique can obtain more accurate results than the existing techniques.

关键词： multi-scale feature point extraction graph cut theory stereo correspondence sparse point matching

Semi-solid Casting of High Speed Steel Ingots Using Inclined Slope Pre-crystallization Method

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Journal of Wuhan University of technology(Materials Science) 2009年第5期24卷 750-752页

作者：和优锋 State Key Laboratory for Fabrication and Process of Nonferrous Metals General Research Institute for Nonferrous Metals

Semi-solid casting of M2.high speed steel ingots was investigated by inclined slope pre-crystallization method. Effects of casting temperature and slope length on the microstructure of M2.HSS ingots were investigated. M2.cast ingots of non-dendritic primary austenite and fine eutectic ledeburite network carbide structure were obtained, with the casting temperature, slope length and angle of 1480 ℃, 500 mm and 60° respectively. Meanwhile, the microstructure of cast samples was quantitatively assessed by Image tool software. Results show that optimum mean equivalent diameter of primary austenite crystal grain is 50.8 μm, shape factor is 0.83, and mean thickness of network carbide is 5.2. μm.

关键词： M2.high speed steel semi-solid pre-crystallization inclined slope

A preliminary study on seismic design criteria of offshore platforms in Bohai Sea of china

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 223-231页

作者： Peng Yanju1,Lu Yuejun1,Yan Jiaquan2.Tang Rongyu1,Wang Junqin3 and Li Jiagang3 1. institute of Crustal Dynamics,china Earthquake Administration,Beijing 100085,china 2. institute of Geophysics,china Earthquake Administration,Beijing 100081,china 3. Beijing research Center of china National Offshore Oil Corp.,Beijing 10002.,china institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

This paper analyzes the seismicity in Bohai Sea,introducing a shape factor K to characterize the seismic risk distribution in sub-regions of the sea. Based on the seismic design ground motions for 46 platforms located in the Bohai Sea,a statistical analysis was performed for different peak ground acceleration (PGA) ratios at two different probability levels. In accordance with the two-stage design method,a scheme of two seismic design levels is proposed,and two seismic design objectives are established respectively for the strength level earthquake and the ductility level earthquake. By analogy with and comparison to the Chinese seismic design code for buildings,it is proposed that the probability level for the strength level earthquake and ductility level earthquake have a return period of 2.0 and 1000 - 2.00 years,respectively. The validity of these proposed values is discussed. Finally,the PGAs corresponding to these two probability levels are calculated for different sub-regions of the Bohai Sea.

关键词： fixed offshore platform seismic design level seismic design objective return period Bohai Sea

V_2._5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

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Science china Chemistry 2009年第7期52卷 1057-1062页

作者： NIU YuLan1,2.& LI RuiFeng1 1 Key Laboratory of Coal Science and technology, Ministry of Education, institute of {2. Chemicals, Taiyuan University of technology, Taiyuan 03002., china 2.Department of Chemical Engineering, Taiyuan institute of technology, Taiyuan 030008, china Key Laboratory of Coal Science and technology Ministry of Education Institute of Special Chemicals Taiyuan University of Technology Taiyuan 030024 China Department of Chemical Engineering Taiyuan Institute of Technology Taiyuan 030008 China

A study of the catalytic activity of V2.5/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH value and there is little oxalic acid from the excessive oxidation of glyoxylic acid. The studies of XRD and TEM have shown that V2.5 diffraction peaks gradually strengthen with the increase of the content of V2.5. With the content of 3% V2.5 and the calcination temperature of 573 K, V2.5/C catalyst displayed the best activity and selectivity. The conversion of glyoxal and the selectivity of glyoxylic acid reached 18.76% and 77.70% after 5 h, respectively. Moreover, V2.5/C catalyst showed small deactivation after recycling three times, which indicates that V2.5/C has a higher stability than noble metal catalysts in the reaction medium.

关键词： glyoxal glyoxylic acid V2.5/C catalyst

Preparation and Electrocatalytic Activity of Polyaniline-poly (Propylene Oxide) Modified by Pt Nanoparticles

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Journal of Wuhan University of technology(Materials Science) 2006年第4期21卷 9-11页

作者：李美超 College of Chemical Engineering and Material Science State Key Laboratory Breeding Base of Green Chemistry-Synthesis TechnologyZhejiang University of TechnologyHangzhou 310032China

The preparation and electrocatalytic activity of polyaniline-poly （ propylene oxide ）（ PAN-PPO ） modified by Pt particles （ Pt/ PAN-PPO ） were investigated. Pt/ PAN-PPO was characterized by scanning electron microscopy （SEM） and energy dispersive spectroscopy （ EDS ）. Pt particles on PAN-PPO were in the nanometer range, and dispersed in a three-dimensional distribution on the surface of PAN-PPO film. Compared with polyaniline and glassy carbon modified with Pt particles under the same conditions, Pt/PAN-PPO exhibited a high electrocatalytic activity for lysine oxidation.

关键词： aniline propylene oxide copolymer platinum electrocatalytic activity lysine

Hydraulic characteristics of converse curvature section and aerator in high-head and large discharge spillway tunnel

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Science china(Technological Sciences) 2011年第S1期54卷 33-39页

作者： LIU ZhiPing 1,2.ZHANG Dong 2.ZHANG HongWei 2.&WU YiHong 1,2.1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,Beijing 100038,china 2.china {2. of Water Resources and Hydropower research,Beijing 100038,china 1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin Beijing 100038 China2. China Institute of Water Resources and Hydropower Research Beijing 100038 China

The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower *** this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,*** the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3 as a platform and combining the k-model and VOF *** flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical *** indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the *** also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side *** means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m/s is proposed.

关键词： spillway tunnel baffling aerator converse curvature section hydraulic characteristics