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51.
52.
The transient response of an upper-convected Maxwell fluid flow in a circular tube is analysed by variational approach of
Kantorovich and the method of finite difference. The solution of the variational method is in agreement with the numerical
results by the difference schemes. The results show that the method of Kantorovich is suitable for the study of non-steady
flow of non-Newtonian fluids and the effect of elasticity of the fluid has an influence on the non-steady flow.
project supported by National Natural Science Foundation of China 相似文献
53.
Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions 下载免费PDF全文
Yueqing Jia Yanjun Fang Prof. Yingkui Zhang Dr. Haralampos N. Miras Prof. Yu‐Fei Song 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14862-14870
The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12O40]3? (PW12) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73Al0.22(OH)2 [PW12O40]0.04?0.98 H2O (Mg3Al‐PW12) has been successfully obtained by applying a spontaneous flocculation method. The Mg3Al‐PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT‐IR, NMR, BET). XRD patterns of Mg3Al‐PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3Al‐PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z‐CH2‐Z′ type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2‐propanol:Vwater=2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3Al‐PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3Al‐PW12‐catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction. 相似文献
54.
Rhodiola, in which there are abundant pharmacologically active ingredients, is one of the functional adaptogenic agent that aid specific bodily functions to adapt to the changes and stress of life in addition to being tonic. In an attempt to qualitatively and quantitatively determine the pharmacologically active ingredients in Rhodiola, a new method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well separated within 24 min at the separation voltage of 18 kV in a 80 mmol L(-1) borax running buffer (pH 9.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 3.16 x 10(-7) to 1.11 x 10(-7)g mL(-1) for all target ingredients. This proposed method has been successfully applied for the analysis of real samples, with satisfactory results. 相似文献
55.
Weimin Lu Bin Wu Lina Wang Yueqing Lu 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):316-318
The title mononuclear complex, [Yb(C5H7O2)3(C12H8N2)(H2O)], is a most uncommon carboxylate complex of a rare earth metal. Each YbIII ion is eightfold coordinated, being bonded to five O atoms of three dimethylacrylate groups, both N atoms of a phenanthroline and one O atom of a water molecule, giving a distorted square antiprismatic coordination polyhedron. 相似文献
56.
根据微循环系统的生理情况,建立了微循环系统动力学非定常、非线性分布参数模型,包括血液动力学、间质动力学、淋巴动力学、蛋白质传输动力学、氧动力学、热量传输动力学和肌原性与代谢性调控过程,综合反映了它们之间的相互作用,并考虑了微动脉自律运动和血液非线性粘弹性的影响.几何模型是一个包括微动脉、开放与储备毛细血管、微静脉、初始淋巴管和微动静脉吻合支的简单网络.这种综合模型有助于临床数据的分析研究和“数值实验手段”的建立. 相似文献
57.
58.
Jie Jing Qing'an Qiao Yueqing Jin Cuihua Ma Honglan Cai Yanfeng Meng Zhengting Cai Dacheng Feng 《中国化学》2012,30(1):133-138
The compatibility of the blend systems for olyactic acid (PLA)/tributyl citrate (TBC) and PLA/glycerol has been studied by molecule and mesoscopic dynamics methods. The results from glass transition temperature simulations showed that the compatibility of PLA/TBC system was better than that of PLA/glycerol, which were consistent with the conclusion obtained from the pair correlation functions. Besides, the behaviors of phase state distribution and evolution process were investigated by mesoscopic dynamics method as well. The results indicated that citrate ester was a better plasticizer than glycerol for PLA. 相似文献
59.
Yttrium doped strontium titanate with A-site deficiency ((Y0.08Sr0.92)1 ? xTiO3 ? δ) was synthesized by conventional solid state reaction. The deficiency limit of A-site in (Y0.08Sr0.92)1 ? xTiO3 ? δ is below 6 mol% in Ar/H2 (5%) at 1500 °C. The sinterability of (Y0.08Sr0.92)1 ? xTiO3 ? δ samples decreases slightly with increasing A-site deficiency level (x). The ionic conductivity of (Y0.08Sr0.92)1 ? xTiO3 ? δ samples increases while the electronic conductivity decreases with increasing A-site deficient amount. The defect chemistry analysis indicates that the introduction of A-site deficiency results in not only the increase of oxygen vacancy concentration but also the decrease of Ti3+-ion concentration. The latter plays the main role in the electrical conduction. (Y0.08Sr0.92)1 ? xTiO3 ? δ shows good thermal-cyclic performance in electrical conductivity and has an excellent chemical compatibility with YSZ electrolyte below 1500 °C. 相似文献
60.
Traditionally, robust and fuzzy support vector machine models are used to handle the binary classification problem with noise and outliers. These models in general suffer from the negative effects of having mislabeled training points and disregard position information. In this paper, we propose a novel method to better address these issues. First, we adopt the intuitionistic fuzzy set approach to detect suspectable mislabeled training points. Then we omit their labels but use their full position information to build a semi-supervised support vector machine (\(\mathrm {S^3VM}\)) model. After that, we reformulate the corresponding model into a non-convex problem and design a branch-and-bound algorithm to solve it. A new lower bound estimator is used to improve the accuracy and efficiency for binary classification. Numerical tests are conducted to compare the performances of the proposed method with other benchmark support vector machine models. The results strongly support the superior performance of the proposed method. 相似文献