Ternary hydrogen-bonded polymer solutions

Ternary-phase diagrams have been experimentally determined at 100°C for systems containing a series of poly(n-alkyl methacrylates), poly(ethylene oxide) (PEO), and a solvent [4-ethyl phenol (EPh)]. A totally miscible phase diagram is experimentally determined for the poly(methyl methacrylate)/PEO/EPh system, while a closed-loop diagram is observed for the analogous system containing poly(ethyl methacrylate). The corresponding phase diagrams of analogous mixtures containing poly(n-propyl methacrylate) or poly(n-butyl methacrylate) exhibit large heterogeneous areas. Theoretically predicted phase diagrams calculated using an association model developed in our laboratory are in general accord with these observations for ternary hydrogen-bonded polymer/polymer solutions. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1265–1271, 1998     

Effect of Zr-ion substitution in CeO2 on H2O2-assisted degradation of orange G

A series of Pd ion-substituted CeO₂–ZrO₂ solid solutions were synthesized using the solution combustion technique. H₂O₂-assisted degradation of orange G was carried out in the presence of the catalysts. The activity of the catalysts was found to increase with the introduction of the second component in the solid solution, as signified by an increase in the rate constants and lowering of activation energy. The study showed the involvement of lattice oxygen and the importance of reducibility of the compound for the reaction.     

Combustion synthesis of (Ti1−xNbx)2AlC solid solutions from elemental and Nb2O5/Al4C3-containing powder compacts

Preparation of the (Ti_1−xNb_x)₂AlC solid solution (formed from the M_n+1AX_n or MAX carbides, where n = 1, 2, or 3, M is an early transition metal, A is an A-group element, and X is C) with x = 0.2-0.8 was investigated by self-propagating high-temperature synthesis (SHS). Nearly single-phase (Ti,Nb)₂AlC was produced through direct combustion of constituent elements. Due to the decrease of reaction exothermicity, the combustion temperature and reaction front velocity decreased with increasing Nb content of (Ti_1−xNb_x)₂AlC formed from the elemental powder compacts. In addition, the samples composed of Ti, Al, Nb₂O₅, and Al₄C₃ were adopted for the in situ formation of Al₂O₃-added (Ti,Nb)₂AlC. The SHS process of the Nb₂O₅/Al₄C₃-containing sample involved aluminothermic reduction of Nb₂O₅, which not only enhanced the reaction exothermicity but also facilitated the evolution of (Ti,Nb)₂AlC. Based upon the XRD analysis, two intermediates, TiC and Nb₂Al, were detected in the (Ti,Nb)₂AlC/Al₂O₃ composite and their amounts were reduced by increasing the extent of thermite reduction involved in the SHS process. The laminated microstructure characteristic of the MAX carbide was observed for both monolithic and Al₂O₃-added (Ti,Nb)₂AlC solid solutions synthesized in this study.     

滑翔飞行器再入段弹道特性分析

为解决滑翔飞行器再入段受力复杂、非线性约束条件多、弹道设计难度大的问题,对平衡滑翔条件下的 弹道解析关系进行分析。根据平衡滑翔的概念,通过简化的动力学微分方程,对滑翔飞行器再入段弹道影响因素进 行分析,联合大气指数模型,推导出平衡滑翔条件下的弹道初始参数与速度、射程以及高度的解析关系,并进行仿 真验证。仿真结果表明：更高的滑翔初速和最优的平衡滑翔初始入射角可以增加滑翔距离,不同高度再入时对射程 影响不大。     

A unified formulation for the biaxial local and global buckling analysis of sandwich panels

Sandwich structures are increasingly employed in many practical applications thanks to their interesting compromise between lightweight and high mechanical properties. However, due to some specific geometric and material features, such structures are subject to global as well as local buckling phenomena, which lead to collapse in most cases. The buckling analysis of sandwich panels is therefore an important issue for their mechanical design. In this respect, this paper is devoted to the theoretical study of the elastic local/global buckling of rectangular sandwich plates under uniaxial or biaxial compression(-tension). Only classical sandwich materials are considered with homogeneous and isotropic core/skin layers. In the present formulation, a Love–Kirchhoff plate model is used to represent the thin skins, whereas the relatively thick core is modeled as a 3D continuous solid. Furthermore, the proposed approach is based on the elastic bifurcation theory in a general 3D framework, and leads to closed-form analytical expressions of the critical loadings and the corresponding bifurcation modes. The accuracy of the derived formulae is checked for both local and global modes by comparison with the results of finite element computations. Parametric analyses are finally performed, investigating primarily the influence of the aspect ratio of the plate and the ratio of the compressive (or tensile) loadings between both directions on the first buckling mode type and the associated minimum critical value.     

CLPS-GA: A case library and Pareto solution-based hybrid genetic algorithm for energy-aware cloud service scheduling

Since the appearance of cloud computing, computing capacity has been charged as a service through the network. The optimal scheduling of computing resources (OSCR) over the network is a core part for a cloud service center. With the coming of virtualization, the OSCR problem has become more complex than ever. Previous work, either on model building or scheduling algorithms, can no longer offer us a satisfactory resolution. In this paper, a more comprehensive and accurate model for OSCR is formulated. In this model, the cloud computing environment is considered to be highly heterogeneous with processors of uncertain loading information. Along with makespan, the energy consumption is considered as one of the optimization objectives from both economic and ecological perspectives. To provide more attentive services, the model seeks to find Pareto solutions for this bi-objective optimization problem. On the basis of classic multi-objective genetic algorithm, a case library and Pareto solution based hybrid Genetic Algorithm (CLPS-GA) is proposed to solve the model. The major components of CLPS-GA include a multi-parent crossover operator (MPCO), a two-stage algorithm structure, and a case library. Experimental results have verified the effectiveness of CLPS-GA in terms of convergence, stability, and solution diversity.     

Hydrogen evolution reaction on spheroidal graphite cast iron with different pearlite areas in sulphuric acid solutions

The rate equation of hydrogen evolution reaction of spheroidal graphite cast iron with different pearlite area has been studied in sulphuric acid solutions at 298 K. The cathodic Tafel slope of ?0·130 V/decade and the reaction order with respect to the activity of hydrogen ion of 1 are obtained by linear potential sweep technique. The rate equation of hydrogen evolution reaction does not depend on the area of pearlite. There is no difference in hydrogen evolution reaction mechanisms between pure iron and spheroidal graphite cast iron.     

Solid-state solutions of copper indium disulfide and zinc indium tetrasulfide: Growth,crystallography and opto-electronic properties

Copper indium disulfide–zinc indium tetrasulfide solid solutions with different contents of zinc indium tetrasulfide, ranging from 4 to 16 mol% were grown by the horizontal modification of the Bridgman–Stockbarger method. Their structural properties were investigated by the X-ray analysis. Spectral dependences of their photoconductivity were analyzed at T≈30 K. In the single crystals with 8–12 mol% of zinc indium tetrasulfide the induced photoconduction phenomenon was observed. It could be explained by the model of three recombination and trapping centers with different capture cross sections. Indium vacancies V_In or substitutional defects Cu_In are possibly the fast recombination centers; meanwhile copper vacancies V_Cu act as the slow recombination centers. The presence of electrically active shallow defects was confirmed by the measurements of the temperature dependences of electrical conductivity and thermally stimulated currents of these samples with n-type conductivity.     

铸铁模材质与工艺探讨

主要探讨影响铸铁机模使用寿命低的各种因素,从诸多因素中找出关键因素,从而寻求解决问题的办法。生产实践表明,通过对有效措施的实施并将其规范后形成制度,有效提升了铸铁模的使用寿命,为公司降本增效做出了突出贡献。     

厄瓜多尔低幅度构造强天然水驱油田开发形势与技术对策

在总结厄瓜多尔低幅度构造强天然水驱油田自2006年2月以来取得的开发成果和已形成的开发配套技术的基础上,分析了油田开发面临的形势和挑战,提出了技术需求和稳产策略。研究区面临的主要开发形势包括：储采比小,储量替换率低,区块稳产基础差;主力油田剩余油分布零散,挖潜难度大;老区可供加密的井位有限;主力油层单一且厚度小,措施实施难度大;设备老化,电力故障频繁,开井时率低。针对研究区的开发形势和挑战,提出了油田开发的技术需求和稳产策略,主要包括低幅度构造识别、剩余油分布预测、水平井开发技术、老井剩余油挖潜、特高含水期稳油控水配套技术和注采系统优化等。