基于第二次土地调查线状地物面积还原研究

在图上进行面积分析时能合理反映地块压盖线状地物的情况是面积分析准确的基础。在第二次土地调查成果基础上,通过一定缓冲算法和多边形节点调整算法,将线状地物还原成面,实现线物面的面积无限接近于线状地物面积的属性值,并通过编码实现,验证了该算法。这种将线状地物面积还原算法简单、灵活、易用,且易于在计算机上编程实现。

Study on Evapotranspiration Regularity of 3 Forages in Eastern Qinghai Province

The transpiration rate and transpiration quantity＇of whole plants and foliages of Bromus innerrnis, Medicago sativa and Agropyron cristatum are measured by using improved quick and continuous weighting after being cut off method （QCWC）. The results show that transpiration rate of branches and foliages of Agropyron cristatum is highest in 3 forages, Medicago sativa is second and Bromus innermis is lowest. From July to September, the average transpiration quantity of whole plants and foliages of 3 forages is highest in August, September is second and July is lowest.

Effect of incorporation manner of Zr promoter on precipitated ironbased catalysts for Fischer-Tropsch synthesis

The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterized by N2 physisorption, temperature-programmed reduction （TPR）, and M6ssbauer effect spectroscopy （MES） techniques. As revealed by N2 physisorption, Zr decreased the BET surface area and pore volume of the catalyst. The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr. The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts＇ stability. In addition, Zr promoter restraines the formation of light hydrocarbons （methane and C2-C4） and shifts the production distribution to the heavy hydrocarbons.

Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes： Electrocatalysis or misinterpretation？

The application of naive Koutecky-Levich analysis to micro- and nano-particle modified rotating disk electrodes of partially covered and non-planar geometry is critically analysed. Assuming strong overlap of the diffusion fields of the particles such that transport to the entire surface is time-independent and one-dimensional, the observed voltammetric response reflects an apparent electrochemical rate o constant koapp, equal to the true rate constant ko describing the redox reaction of interest on the surface of the nanoparticles and the ratio,ψ, of the total electroactive surface area to the geometric area of the rotating disk surface. It is demonstrated that Koutecky-Levich analysis is applicable and yields the expected plots of I-1 versus ω-1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof koapp, not ko. Thus, for ψ 〉 1 apparent electrocatalysis might be naively but wrongly inferred whereas for ψ 〈 1 the deduced electrochemical rate constant will be less than ko. Moreover, the effect of ψ on the observed rotating disk electrode voltammograms is significant, signalling the need for care in the overly simplistic application of Koutecky-Levich analysis to modified rotating electrodes, as is commonly applied for example in the analysis of possible oxygen reduction catalysts.

Hierarchical TiO2 photocatalysts with a one-dimensional heterojunction for improved photocatalytic activities

Hierarchical TiO2 photocatalysts with a one-dimensional heterojunction were synthesized via a facile template-free hydrothermal method. The TiO2 photo- catalysts were flower-like microspheres with a 3 μm diameter. The base structure of the flower-like microspheres was a uniform nanowire with a 10 nm diameter. Anatase films were evenly coated onto the surface of the rutile TiO2 nanowires to form a one-dimensional core--shell base structure. This kind of one-dimensional heterojunction is conducive to the separation of charge carriers. In addition, the hierarchical TiO2 microspheres possessed a good mesoporous structure with a high specific surface area of 260 m2/g. Thus, the light scattering and utilization efficiency were improved in this structure. The photocatalysts exhibited better performance in both photocatalytic oxidation and reduction reactions. Moreover, the novel TiO2 photocatalysts displayed excellent stability in these reactions. This kind of hierarchical TiO2 structure has never been reported in the literature. The hierarchical structure and one-dimensional heterojunction were vital to the increase in quantum efficiency. Therefore, these hierarchical TiO2 photocatalysts have potential applications in the environmental and energy fields, such as in photocatalytic degradation, hydrogen production, Li-ion batteries, and dye-sensitized solar cells.

MoS2-wrapped silicon nanowires for photoelectro- chemical water reduction

Integration of molybdenum disulfide （MoS2） onto high surface area photocathod is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction （HER）. Semiconductor nanowires （NWs） are beneficial use in photoelectrochemistry because of their large electrochemically availab surface area and inherent ability to decouple light absorption and the transpo of minority carriers. Here, silicon （Si） NW arrays were employed as a mod photocathode system for MoS2 wrapping, and their solar-driven HER activil was evaluated. The photocathode is made up of a well-defined MoSJTiO2/Si coaxial NW heterostructure, which yielded photocurrent density up to 15 mA/cm2 （at 0 V vs. the reversible hydrogen electrode （RHE）） with goo stability under the operating conditions employed. This work reveals the earth-abundant electrocatalysts coupled with high surface area NW electrod~ can provide performance comparable to noble metal catalysts for photocathod hydrogen evolution.