Sparse representation-based classification algorithm for optical Tibetan character recognition

A sparse representation-based two-phase classification algorithm is proposed for off-line handwritten Tibetan character recognition. The first phase realizes coarse classification with the K-NN classifier by finding the K nearest neighbours of a test sample in the dictionary constructed by K-SVD with samples of all classes, and the classes of these neighbours are regarded as the candidate classes of the test sample. The second phase performs fine classification with the sparse representation classifier by sparsely representing the test sample with all elements of the dictionary constructed by K-SVD with samples of all candidate classes, and the test sample is finally classified into the candidate class with the maximal contribution in sparse representation. Experiments on the Tibetan off-line handwritten character database show that an optimal recognition rate of 97.17% has been reached and it is 2.12% higher than that of K-NN.     

斑头雁不同组织氨基酸的组成和含量分析

采用高效液相色谱法对斑头雁卵、肌肉和羽毛中17种氨基酸进行了含量的测定,并分析其中必需氨基酸的含量,为斑头雁的保护和利用提供依据。结果表明,斑头雁的卵、腿肌、胸肌和羽毛中均含有17种氨基酸,必需氨基酸含量较高,配比合理,有较高的营养价值。     

Temperature independent leakage current in Au/TbMnO3/Y Ba2Cu3O7−x capacitors

Au/TbMnO₃/Y Ba₂Cu₃O_7?x capacitors were fabricated on LaAlO₃ substrates and electrical characteristics were studied in the temperature range from 300 to 25 K. When temperature is higher than 225 K, Ohmic conduction is observed in the capacitors. Non-linear current–voltage characteristics are exhibited at low temperatures. Moreover, temperature-independent leakage currents are found at temperatures lower than 150 K. These electrical characteristics can be explained in terms of conduction transition originated from a thermal activation between 225 and 150 K, and the temperature-independent leakage currents are governed by the Poole–Frenkel emission and minor trap ionization energies.     

Influence of graphene nanoplatelet content on the electromagnetic and microwave absorbing properties of BiFeO<Subscript>3</Subscript>/GNP/epoxy composites

Ternary composites of BiFeO₃/graphene nanoplatelet (GNP)/epoxy composites were synthesized and its electromagnetic and microwave absorbing properties were studied; the main absorbing mechanism was illustrated. The phase, microstructure, and microwave absorbing properties were characterized by X-ray diffraction, scanning electron microscope, and vector network analyzer. The results indicated that the BiFeO₃ was successfully synthesized and the GNP was uniformly distributed in the composites, and the complex permittivity of BiFeO₃/GNP/epoxy composites increased with increasing the GNP content due to the interface polarization and conductance loss. The minimum reflection loss value was reached to ??45 dB at 9.25 GHz with the thickness of 1.4 mm when the GNP content was 2 wt%, and also the absorbing properties of (BiFeO₃+GNP)/epoxy composites can be tailored by the GNP content and composite thickness, which may be used as a kind of absorbing materials with good absorbing performance and low density.

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Graphical abstract The reflection loss curves and the simulated matching thickness of GNP-BiFeO₃-epoxy composites with 2 wt% GNP content. As can be seen, the minimum reflection loss value was reached to ??45 dB at 9.25 GHz with the thickness of 1.4 mm, and also the quarter-wavelength matching theory can be used to illustrate the good absorbing properties of GNP-BiFeO₃-epoxy composites.

     

Four Mixed 3d-4f 12-Metallacrown-4 Complexes: Syntheses,Structures and Magnetic Properties

The incorporation of Ln^III ions into the 12-metallacrown-4 topology affords the formation of four mixed 3d-4f pentanuclear complexes of compositions [NH(C₂H₅)₃]{[Ln(OAc)₄] [12-MC _Mn ^III _(N)shi-4]}·xH₂O (Ln = Sm (1), Gd (2), Tb (3), Dy (4); x = 0.5 for 1 and 3, x = 0.25 for 2, x = 0 for 4; H₃shi = salicylhydroxamic acid). Compounds 1–4 were obtained from the reactions of H₃shi with Mn(CH₃COO)₂·4H₂O and Ln(NO₃)₃·6H₂O, in the presence of N(C₂H₅)₃. They all contain a crown-like [Mn₄Ln(μ-NO)₄]¹¹⁺ core with four Mn^III atoms being at the rim of the crown and an Ln^III ion occupying the dome of the crown. The peripheral ligation about the core is provided by four η¹:η¹:µ acetate groups. The identity of the Ln^III ions slightly affects the 12-metallacrown-4 frameworks, as demonstrated by the gradual decrease of the distances between the Ln^III ions and the centres of the Mn₄ planes (1.85 Å for 1, 1.81 Å for 2, 1.80 Å for 3, and 1.77 Å for 4). Variable-temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4. Antiferromagnetic interactions are determined for complexes 1–4.     

环境样品中痕量锑的形态分析研究进展

环境样品中不同形态锑,其生物活性及其毒性不同,其形态分析具有重要意义。由于环境样品中锑的含量相对较低,不同形态锑的分析具有挑战性。归纳总结了环境样品中痕量超痕量锑的形态分析概况及近年来的发展趋势,内容主要包括样品的前处理和不同形态锑的分析方法,指出了未来的发展方向。     

正热电离静态多接收偏硼酸铯离子测定硼同位素

利用表面热电离质谱仪(Triton TI)的"Zoom Quad"功能,采用静态多接收偏硼酸钯离子(Cs2BO+2)测定标准样品NIST 951 H3BO3和珊瑚与有孔虫样品的硼同位素,研究了涂样量对硼同位素组成测定的影响,探讨静态多接收与传统的动态峰跳扫方法相比,在测定精度、准确度、样品量以及测试时间上的优势.实验结果表明,在测试精度和准确度相同的情况下,静态双接收所需样品量可以低至0.1 μg,且测试时间可缩短一半.对0.1 μg NIST 951 H3BO3静态双接收测定的硼同位素比值11B/10B = 4.05159±0.00023(2σm, n=10),与世界主要实验室的测试值相符.最后对0.1 μg珊瑚和有孔虫样品进行了测定,也取得了较好的结果.     

Correlation between Boron Isotope of Coral Acropora and pH Value of Seawater Surface

A water circulation system with the almost same element composition and socket type was adopted in coral Acropora culture under different seawater pH value conditions and the data of the relationship between boron isotopic compositions of coral and seawater pH value by thermoelectric ionization mass spectrometer were obtained. According to the correlations between α_carb-3 of coral and the pH value of cultured seawater, α_carb-3 was not a constant but related to pH value, indicating that B(OH)₃ also incorporated carbonate. Therefore, the theoretical formula could not be used to calculate the seawater pH value from the δ¹¹B_carb value of the measured marine biological carbonate. The empirical equations obtained experimentally would be an alternative method to calculate the seawater pH value. In addition, the mixed precipitation of CaCO₃ and Mg(OH)₂ was found in aquaculture tanks with high pH value, and the δ¹¹B of the solid was significantly higher than that of cultured seawater. The result indicated that the presence of Mg(OH)₂ had a significant effect on the boron isotope fractionation, which deserved our attention.     

Physicochemical properties of ionic liquid analogue containing magnesium chloride as temperature and composition dependence

The ionic liquid analogue containing MgCl₂ based on choline chloride and glycerol was reported. The solubility of MgCl₂ in the ionic liquid analogue based on choline chloride and glycerol was measured from T?=?293?C393?K. The empirical equation about the solubility and temperature was obtained. Thermal analysis showed that the ionic liquid analogue was stable from room temperature to 140?°C. The physical properties such as conductivity ??, density ?? and viscosity ?? of ionic liquid analogue were measured as function of the content of MgCl₂ and temperature. An empirical equation about the density (??) and temperature was obtained. The ions transport behaviours are analyzed using hole-theory. It is shown that the conductivity of the ionic liquid analogues is controlled by the ion mobility and the suitable voids.     

Studies on the thermal decomposition of N,N'-ethylenebis(salicylideneiminato) diaquochromium(III) nitrate

A complex of N,N'-ethylenebis(salicylideneiminato)diaquochromium(III) nitrate, [Cr(salen)(H₂O)₂]NO₃ was characterized and its decomposition mechanism was studied by TG. The IR spectrum and X-ray analysis were examined for the complex. The non-isothermal kinetic data were analyzed by means of the Achar method and the Coats—Redfern method. The most probable kinetic model function was suggested by comparison of the kinetic parameters.This revised version was published online in November 2005 with corrections to the Cover Date.