Decision tree classification of land cover from remotely sensed data

Decision tree classification algorithms have significant potential for land cover mapping problems and have not been tested in detail by the remote sensing community relative to more conventional pattern recognition techniques such as maximum likelihood classification. In this paper, we present several types of decision tree classification algorithms arid evaluate them on three different remote sensing data sets. The decision tree classification algorithms tested include an univariate decision tree, a multivariate decision tree, and a hybrid decision tree capable of including several different types of classification algorithms within a single decision tree structure. Classification accuracies produced by each of these decision tree algorithms are compared with both maximum likelihood and linear discriminant function classifiers. Results from this analysis show that the decision tree algorithms consistently outperform the maximum likelihood and linear discriminant function classifiers in regard to classf — cation accuracy. In particular, the hybrid tree consistently produced the highest classification accuracies for the data sets tested. More generally, the results from this work show that decision trees have several advantages for remote sensing applications by virtue of their relatively simple, explicit, and intuitive classification structure. Further, decision tree algorithms are strictly nonparametric and, therefore, make no assumptions regarding the distribution of input data, and are flexible and robust with respect to nonlinear and noisy relations among input features and class labels.

平原井灌区土壤水库调蓄能力分析

20世纪80年代以来,由于干旱少雨,北方井灌地区农田地下水位普遍下降,由此使得农田土壤的蓄水能力发生变化。论文根据北京市水利科学研究所在北京市东南郊水资源试验区取得的试验资料,以0～3m土层作为土壤水库的界定深度,分析其对降雨的调蓄能力;经计算,1991～1995年间,春末夏初雨季前,土壤水库的有效调节能力,多年平均值为137.4mm(0～2m)和188.8mm(0～3m)。分析表明,0～3m层土壤有很好的蓄雨调节能力,雨季平均有近85%的降水量滞蓄在3m土层内,其余蒸腾、蒸发散失或补给地下水。研究认为,在田间采取一定的拦蓄水措施,即使遇到10年一遇24小时p=200mm这样的大暴雨,是可以做到农田地表不产流或少产流,从而最大限度地拦蓄汛期降水,增加土壤水资源量的。

水肥耦合条件下春小麦叶片的光合作用

采用312-D最优饱和设计,在辽宁西部半干旱区进行了田间春小麦光合作用试验研究．结果表明:叶片光合速率与籽粒产量正相关．水肥单因子对叶片光合速率影响的大小顺序是,氮>水>磷．交互耦合作用对叶片光合速率影响的大小顺序为:氮与水耦合>氮与磷耦合>磷与水耦合．水肥耦合促进叶片光合速率提高的主要原因是:扩大了叶面积、提高了叶片蒸腾速率、增大了叶片气孔导度、提高了胞内水浓度、降低了胞内二氧化碳浓度．单叶光合速率高于7．5×10-3μmol／s的水肥优化管理方案是:施氮量为323．4-399．9 kg／hm2、施磷量为65．8-105．7 kg／hm2、灌水量为276．1-353．2 mm．

Layer-by-layer assembly of carbon nanotubes and Prussian blue nanoparticles: A potential tool for biosensing devices

A promising method for assembling carbon nanotubes (CNTs) and poly(diallyldimethylammonium chloride) protected Prussian blue nanoparticles (P-PB) to form three-dimensional (3D) nanostructured films is proposed. The electrostatic interaction, combined with layer-by-layer self-assembly (LBL), between negatively charged CNTs and positively charged P-PB is strong enough to drive the formation of the 3D nanostructured films. Thus, prepared multilayer films were characterized by ultraviolet-visible-near-infrared spectroscopy (UV-vis-NIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV).

Age hardening and mechanical properties of Mg-Gd-Er alloy

The Mg-8Gd-0.6Zr-xEr (x = 1, 3 and 5 mass%) alloys were prepared by casting technology, and the microstructures, age hardening behaviors and mechanical properties of alloys have been investigated. Microstructures of the alloys are characterized by the presence of rosette-shaped equiaxed grains. The age hardening behaviors and the tensile properties are enhanced by adding Er element. The maximum aged hardness of Mg-8Gd-0.6Zr-5Er alloy is 97, it is nearly 1.24 times higher than that of Er-free alloy.

Novel spiro-fluorenes from tandem radical addition for liquid crystalline monodisperse conjugated oligomers

3'-Nonafluorobutylmethyl-4'-methyl-spiro[cyclopentyl-9,1']fluorenes were successfully synthesized via tandem radical-addition reactions between 9,9-diallylfluorenes and perfluorobutyl iodide in the presence of a radical initiator followed by reduction under mild conditions. Single crystal analysis indicates that two substituents at 3,4-positions of cyclopentane are in a maleinoid form. Accordingly, four oligo(fluorene-co-bithiophene)s with the same molecular length of similar to 10 nm (7 fluorene units and 12 thiophene units) containing one to three novel spiro-fluorene units were synthesized.

利用Cyanex 923和离子液体的复合材料分离钇及重稀土

提供了一种固定Cyanex 923的新方法-溶胶-凝胶法。在溶胶-凝胶过程中离子液体的加入增加了复合材料的比表面积和孔容,并在硅胶网络中为Cyanex 923提供了一个可以扩散的介质。包埋离子液体和Cyanex 923的有机-无机复合材料的制备过程不需要其他有机溶剂,绿色、环保。结果表明,该复合材料对Y(Ⅲ)和重稀土元素有较好的分离效果。经过4次萃取/反萃过程,该复合材料对Y(Ⅲ)去除率仍高于78%。表明材料性能稳定,可多次重复使用。

Synthesis, structure and photochromic properties of a novel 1,6-hexanediamine trimolybdate supramolecular compound

A novel supramolecular compound 1,6-hexanediamine trimolybdate ((C6H18N2[Mo3O10], denoted as HDAMo) has been synthesized by a hydrothermal method and its structure has been characterized by elemental analyses, Fourier transform infrared (FT-IR) spectra, single-crystal X-ray diffraction (XRD) technique. This single crystal compound consists of protonated 1,6-hexanediamine (HDA) cations and polyoxometalate [Mo3O10](2-) anions. Its crystal structure belongs to monoclinic system (space group P2(1)/n) with a = 7.7508(14), b = 11.467(2), c = 16.167(3) angstrom, beta = 92.689(3)degrees, V = 143 5.3(5) angstrom(3), Z = 4 and D-ealc = 2.619 g cm(-3). The final statistics based on F-2 are GOF = 0.980, R-1 = 0.0261 and wR(2) = 0.0506 for I > 2 sigma(I). XRD analysis revealed that in the crystal structure of HDAMo, novel infinite [Mo3O10](2-) chains parallel to a axis are made up of distorted MoO6 octahedra connected by corners and edges. The protonated HDA cations occupy channels formed by [Mo(3)O3(10)](2-) Chains and exhibit strong hydrogen bond interactions to terminal and bridging oxo groups of the chains. The [Mo3O10](2-) chains linked through protonated HAD cations formed a one-dimensional network. The HDAMo compound shows novel photochromic properties, i.e., its color changes from white to reddish brown gradually under UV irradiation. XRD, FT-IR, ESR spectra and XPS are used to investigate the photochromic behavior of the compound.

4f~(N-1)5d组态自旋允许与禁戒跃迁能级的研究

通过稀土光谱理论,计算了三价稀土离子的4fN-15d组态能级的f与d电子间的库仑相互作用,结果表明对于重稀土元素,其自旋允许跃迁能级位置高于自旋禁戒跃迁能级位置,并且两种能级间的能级差随f电子数的增加而依次减小。对于轻稀土元素,则自旋禁戒跃迁能级位置高于自旋允许跃迁能级位置。结果很好地解释了自旋禁戒跃迁能级的光谱现象。

High order liquid crystalline structure of poly(11-{[(4 '-heptyloxy-4-biphenylyl)carbonyl]oxy}-1-undecyne)

Liquid crystalline properties of a mesomorphic polyacetylene {-[HC=C(CH2 )(9)OOC-Biph-OC7H15](n)- (PA9EO7), Biph=4-4'-biphenylyl} are investigated by X-ray diffraction, polarizing optical microscope, and transmission electron microscope. Polyacetylene PA9EO7 from solution adopts a sandwich structure, which is a high order smectic phase. The biphenylyl pendants pack in a hexagonal fashion and the distance between two appendages is 4.51 Angstrom. The heptyloxy tails on one polymer backbone overlap with those on the neighboring chain. The nonyl spacer and the heptyloxy tail exhibit a hexagonal packing arrangement with intermolecular distance of 3.24 Angstrom.

钙改性对r-Al2O3的高温热稳定性的影响

中国科学院山西煤炭化学研究所

Hydrothermal synthesis and crystal structure of a novel layered compound [Ni(C10H8N2)(2)V3O8.5]

A novel layered compound, [Ni(C10H8N2)(2)V3O8.5], was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. The compound crystallizes in monoclinic system, space group P21/c with a = 1.551 8(3) nm, b = 1.476 1(3) nm, c = 1.048 3(2) nm, beta = 92.02(3), V = 2.399 8(8) nm(3), Z = 4, R = 0. 046 7, wR(2) = 0. 085 9.

Synthesis and characterization of phenyl-capped oligoanilines

A series of phenyl-capped oligoanilines were prepared by chemical oxidation coupling. By comparing the FTIR spectra of fully reduced oligoanilines with those of oxidized oligoanilines, the intensity ratio of 1600cm(-1) to 1500cm(-1) was correlated to the content of the quinoid rings in the oligomer. In UV-Vis spectra of the oligoanilines in their oxidized state, the maximum absorption near 600nm redshifted from 540nm to 610nm with increasing polarity of the solvent, indicating the existence of tautomers in oxidized oilgoanilines.