ISSN 0253-2778

CN 34-1054/N

2011 Vol. 41, No. 5

Display Method:
Ricci flow on surfaces with Gaussian curvature of initial metrics unbounded below
CHEN Qing, YAN Yajun
2011, 41(5): 377-383. doi: 10.3969/j.issn.0253-2778.2011.05.001
The existence of Ricci flow on 2-dimension open manifolds with the Gaussian curvature of initial metrics unbounded below was proved. The initial metric can be either complete or incomplete.
Bi-cubic non-uniform B-spline surface reconstruction for slice contours
WANG Yu, ZHENG Jinjin, ZHOU Hongjun, SHEN Lianguan
2011, 41(5): 384-391. doi: 10.3969/j.issn.0253-2778.2011.05.002
A surface reconstruction method from the slice contours was proposed. First, feature points were extracted based on curvature feature, and they were resampled in order to get a unification of sampling points in each line (column). Then, the sampling points were interpolated to get a bi-cubic non-uniform B-spline surface. Finally, nodes were inserted on the surface based on distance feature at a certain control accuracy, and the new control points through the least-squares approximation method were calculated to get approximate surface within the permissible range error. Based on the characteristics of slice contours, B-spline cycle and non-cycle B-spline combined, and the calculation of closed and non-closed surface was discussed. It was found that the combination of interpolation and approximation makes the algorithm more rapid and practical.
Arc-length preserving approximation of circular arcs by polynomial curves with lower degrees
WANG Xuhui, DENG Jiansong
2011, 41(5): 392-398. doi: 10.3969/j.issn.0253-2778.2011.05.003
Arc-length-preserving approximation of circular arcs by cubic Bézier and quartic PH curves was discussed. For cubic Bézier curves, the relation between the length of the curve and the distance of adjacent control points was explored. Hence, a robust numerical method was derived to determine the control points of the curve. Accurate solutions were also provided for quartic PH curves to approximate circular arcs. The results show that polynomial curves with lower degrees can approximate circular arcs with high precision with the requirement of preserving arc-length.
Initial applications of threshold photoelectron-photoion coincidence velocity imaging technique
TANG Xiaofeng, ZHOU Xiaoguo, NIU Mingli, LIU Shilin, LIU Fuyi, SHAN Xiaobin, SHENG Liusi
2011, 41(5): 399-407. doi: 10.3969/j.issn.0253-2778.2011.05.004
Threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging based on synchrotron radiation ionization utilizes a double velocity map imaging to simulateneously control the trajectories of electron and ion, thus improving their collection efficiencies and energy resolutions. Using this technique, some experimental investigations of atoms and molecules were performed, and the corresponding threshold photoelectron spectroscopy (TPES), TPEPICO time-of-flight mass spectroscopy, TPEPICO spectroscopy, and TPEPICO velocity imaging were measured. Therefore, this novel technique can be applied to studies of ionic structure, identification of components in mixture and dissociation dynamics of state-selected ions.
CuInSe2 thin films synthesized by sol-gel method with nitrates as precursors
CHEN Xiangzhou, CHEN Guilin, LIU Weifeng, ZHU Changfei
2011, 41(5): 408-413. doi: 10.3969/j.issn.0253-2778.2011.05.005
High quality chalcopyrite CuInSe2 films were synthesized by a non-vacuum solution method using nitrates as sources for low-cost photovoltaic applications. The solution based on nitrates was used for precursor films by the spin-coating process, and sequential reduction and selenization treatments were performed with hydrogen and Se vapor, respectively. Through X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM) and Raman scatting measurements, it was found that uniform, high crystalline and crack-free films were obtained using this simple method. Also, the films exhibited Cu2-xSe secondary phase free property, indicating the excellent quality of the synthesized CuInSe2 thin films. Finally, the phenomenon and mechanism of the two-layered structure formation of the synthesized CuInSe2 thin film were discussed.
Synthesis and visible-light photocatalytic activity of Ag/TiO2 ordered porous composite films
ZHAO Yongxun, YANG Beifang, FU Zhengping
2011, 41(5): 414-421. doi: 10.3969/j.issn.0253-2778.2011.05.006
TiO2 ordered porous films (TIO) were fabricated via TiCl4 sol-gel dip-coating process using self-assembly SiO2 colloidal crystal as templates and Ag nanoparticles were achieved on the TIO by a liquid infiltration route, and Ag/TiO2 ordered porous composite films (ATIO) were obtained. The characteristics of the composite films were measured by Raman, FESEM, TEM, XPS and UV-vis. The results reveal that the average size of Ag nanoparticles is about 10 nm, and strong interaction exists between Ag nanoparticles and TiO2 nanocrystals. Visible light photocatalytic activities of samples with different Ag/Ti relative atomic concentration ratios and cycling tests were evaluated by analyzing the degradation of methylene blue (MB) in aqueous solution, and were compared with Ag/TiO2 disordered composite films (ATF). It is found that the TIO with AgNO3 concentration value 10 mmol/L in the precursor solution exhibits 319 times visible light degradation rate compared with conventional Ag deposited TiO2 disordered film without the ordered porous structure. This obvious enhanced visible-light photocatalytic activity for the Ag deposited TIO sample can be attributed to the synergetic effect of Ag nanoparticles and TIO ordered porous structures. The repeated cycling tests suggest that samples show stable photocatalytic activity.
Study on the influencing factors of the model Maillard reaction of L-phenylalanine/D-glucose at physiological temperature
XIA Bingle, LIU Yongjun
2011, 41(5): 422-427. doi: 10.3969/j.issn.0253-2778.2011.05.007
The color intensity of Maillard reaction products (MRPs), between D-glucose and L-phenylalanine at 37 ℃ and pH 65 for 1~35 d, was analyzed. The effects of metal ions (Fe2+ and Cu2+) and the water content in solvent on Maillard browning were also monitored. The results show that the rate of the model Maillard reaction is inversely proportional to water content, the reaction rate increasing with the decrease of the water content. Browning tends to be accelerated in the presence of Fe2+ and Cu2+ and the reaction time is shortened effectively. Their catalysis increases first and then decreases with the increase in the concentration of metal ions. The catalysis is strongest when the concentrations of Fe2+ and Cu2+ are 02 mmol/L, and the browning reaction is somewhat faster in the presence of Cu2+ than of Fe2+.
Biocompatibility and cellular uptake of surface-modified gold nanorods
FANG Wenyan, MIN Yuanzeng, XU Mai, ZHU Chuangao
2011, 41(5): 428-431. doi: 10.3969/j.issn.0253-2778.2011.05.008
Surface modified gold nanorods which are hexadecyltrimethylammonium bromide (CTAB) stabilized were obtained and their biocompatibility and function of delivering fluorescent molecules into cells were also studied. The CTAB stabilized gold nanorods were surface modified with polyethylene glycol (PEG) through in situ dithiocarbamate formation and ligand exchange. The surface modified gold naorods (PEG-GNRs) with terminal amine on its surface was prepared. The shape and optical properties of surface modified GNRs were characterized by transmission electron microscope (TEM) and UV-Vis. Then, the biocompatibility of PEG-GNRs was measured with MTT assay. A confocal laser scanning microscope (CLSM) and a fluorescence activated cell sorter (FACS) were employed to study PEG-GNRs function of delivering fluorescence molecules into cells. Results show that PEG-GNRs have good compatibility and can be used as a vector for delivering fluorescent molecules or drug into cells for cell imaging in the future.
Nano-indentation test of visco-elastic materials and the influence of contact geometry on indentation
HONG Lei, SU Yahui, TIAN Jie, HUANG Wenhao
2011, 41(5): 432-438. doi: 10.3969/j.issn.0253-2778.2011.05.009
Instrumented nano-indentation was performed on polyvinyl chloride (PVC) material and finite element method (FEM) calculation was used to simulate the nano-indentation experiment. The data of the FEM calculation and nano-indentation experiment were compared. It was concluded that the method of using FEM to simulate experiments of nano-indentation into visco-elastic materials is feasible. Four 2D axisymmetric FEM modules of conical-indenters with different tip radii were built to interact with PVC. The simulation results show that the measured hardness increases with the tip radius and decreases with the depth of indention in nano-indentation of visco-elastic materials. Indenter dimension index was employed to help establish two FEM modules classified by the difference between the indenter dimension index and surface roughness. The simulation results indicate that the measured hardness is under or over the proper value when the point of surface contact is at its maximum or minimum and that the deviation of hardness increases with that of roughness as well as the distance between the ripples.
Kinematic model and calibration of an articulated arm coordinate measuring machine
CHENG Wentao, YU Liandong, FEI Yetai
2011, 41(5): 439-444. doi: 10.3969/j.issn.0253-2778.2011.05.010
Based on D-H (Denavit-Hartenberg) notation, the measurement model and calibration technology for a seven-axis articulated arm coordinate measuring machine (AACMM) were researched. The number and definitions of kinematic model parameters were further studied. Simulation experiments revealed a special problem: some parameters can not be effectively identified by direct calibration. To solve the problem, a vertical rod was made and fitted into the probe to identify all parameters of the seven-axis AACMM. Finally, the probe was calibrated by placing the straight rod back and the probe parameters could be obtained. Not only can the experiments prove that the method presented can guarantee the precision of the AACMM with seven axes by identifying all parameters, but they can also verify the validity of the kinematic model.
Experimental study on flame stability characteristics of porous medium bluff-bodies
XU Sheng, LIU Minghou, XU Kan, LU You
2011, 41(5): 445-451. doi: 10.3969/j.issn.0253-2778.2011.05.011
Porous media were investigated for the preparation of flame holders, for porous medias permeability and dispersivity can bring down pressure loss and improve the ratio of fuel and air after the bluff-bodies. Based on the comparative trials of a solid bluff-body and another two with 10PPI (pores per inch) and 40PPI, respectively, it was found that the porous media flame holder can have a wider range of flame stability. Under the same fuel and air co-flow conditions, a porous medium makes burning more complete, and the flame more rigid. The recirculation zone of a solid bluff-body is closer to the bluff-body and the back flow intensity is stronger than that of a body made of porous media. Hence, considering the pressure loss and the effects of fuel and air mixing, an appropriate diameter of porous media is the key to stabilizing flames.
Study on the development of Guangdongs electricity power under CO2 emission constraints
YI Jingwei, ZHAO Daiqing, HU Xiulian, CAI Guotian
2011, 41(5): 452-458. doi: 10.3969/j.issn.0253-2778.2011.05.012
In order to tackle climate change, China has promised to reduce CO2 emissions per unit of GDP by 40%~45% in 2020 compared with that in 2005, and Guangdong must follow suit. A techno-economic model was built to analyze the structure, energy consumption and CO2 emission of Guangdongs electricity supply system in three scenarios with different CO2 reduction pressures until 2020. The result shows that it is a reasonable target for Guangdong to reduce about 25% of CO2 emissions per unit electricity supply in 2020 compared with that in 2005. The chief measures to achieve the target are as follows: continue developing nuclear power, increasing the electric power installed capacity from 58% in 2007 to about 20% in 2020; phasing out thermal power stations with unit capacity less than 200 MW to a total of 8 000 MW, develop wind power, increasing the electric power installed capacity from 04% in 2007 to more than 10%; and develop natural gas power appropriately.
Synthesis of sugar and fixation of CO2 through artificial photosynthesis driven by hydrogen or electricity
HUANG Weidong
2011, 41(5): 459-468. doi: 10.3969/j.issn.0253-2778.2011.05.013