Interpenetrating polymer network structured thermosets prepared from epoxidized soybean oil/diglycidyl ether of bisphenol A

Epoxidized soybean oil (ESO)/diglycidyl ether of bisphenol A (DGEBA) in various blend ratios (i.e. 100/0, 90/10, 80/20, 70/30, 60/40, 50/50) was thermally cured using methylhexahydrophthalic anhydride in the presence of 2‐ethyl‐4‐methylimidazole catalyst. The tensile properties and fracture toughness of the ESO/DGEBA thermoset blends were determined. Thermal properties of the blends were characterized using dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis. Blending of ESO and DGEBA gave synergistic effects on the modulus, strength, glass transition temperature and thermal stability. However, the fracture toughness and elongation at break of ESO/DGEBA blends are lower than those of ESO, as expected. The enhancement in certain mechanical and thermal properties of ESO/DGEBA can be associated with the crosslink density, gel content and possible interpenetrating network of the resulting thermoset blends. © 2013 Society of Chemical Industry     

Effects of Two-Photon Absorption on Pump-Induced Refractive-Index Change in AlAsSb–InGaAs–AlAs Optical Waveguides

Injection of transverse-magnetic polarized 1.55- mum pump light pulses having an excessively high intensity into heavily-doped AlAsSb-InGaAs-AlAs coupled-double-quantum-well optical waveguides causes a large amount of electrons in the ground state of the subbands in the conduction band to transit to the excited state and results in bandgap shrinkage as well as a large amount of vacant sites in the ground state. Consequently, the simultaneously injected continuous-wave transverse-electric polarized 1.54- mum probe light is absorbed by the valence-band electrons through two-photon absorption (TPA) and transit to the vacant sites in the ground state of the subbands in the conduction band. As a result, the probe power is reduced instantaneously but recovers at a time constant in the order of 10^-10s. A theoretical evaluation of the effect of the above intersubband-pump-assisted TPA of the probe light shows that the pump-induced net refractive-index change in these devices is reduced by 50% when intersubband absorption and ISB-pump-assisted TPA of the probe light are of equal strength. Characterization of the TPA in these devices indicates that these devices have a TPA coefficient of 25 cm/GW.     

Synthesis and formation mechanism of hematite hollow microspheres by a one-pot templateless surfactant-free hydrothermal process

Hollow microspheres of hematite (α-Fe₂O₃) were prepared by a simple hydrothermal treatment of ferrous ammonium sulphate hexahydrate ((NH₄)₂Fe(SO₄)₂·6H₂O) aqueous solution without any surfactants and additives at 180–200 °C. The products were characterized by XRD, FE-SEM and TEM. The results show that α-Fe₂O₃ hollow microspheres are about 1 μm in diameters and are composed of α-Fe₂O₃ nanoparticles with a diameter range from 50 nm to 150 nm. The effects of reaction parameters such as reaction time, temperature and [(NH₄)₂Fe(SO₄)₂·6H₂O] on the morphology of the final product were investigated. A potential formation mechanism of α-Fe₂O₃ hollow microspheres was also proposed, where the intermediate, urchin-like goethite, served as a sacrificial template for the formation of hollow structure. The reaction parameters-depended morphologies of the final products consisted well with the proposed formation mechanism.     

公众参与式水库移民安置点选址决策的博弈分析

安置点选址决策是移民安置规划的基础性工作，如何实现稳定和谐移民一直以来都是规划设计人员深入探索的问题。将公众参与模式引入移民安置点选址的决策中，可以保证各方的合理利益，力求移民安置点选址决策过程的公平合理性。同时，安置点选址的决策过程具有博弈的典型特征，因此，从博弈视角研究参与式移民安置点选址决策，对科学合理地确定移民安置点具有非常重要的理论与现实意义。     

偏三甲苯催化氧化法制备2,3,5-三甲基苯醌的研究

采用水热合成法合成了铜酞菁与γ-Al2O3复合的催化剂Y。冰醋酸为溶剂,H2O2为氧化剂,用催化剂Y将偏三甲苯一步催化氧化为标题化合物(维生素E重要中间体)。考察了催化剂用量、pH、反应时间、温度和双氧水等因素对该反应体系的影响。催化剂Y对反应体系具有较好的催化效果,TMB的转化率达72.8%,TMBQ产率达65.3%。     

A DISCRETE TIME TWO-LEVEL MIXED SERVICE PARALLEL POLLING MODEL

We present a discrete time single-server two-level mixed service polling systems with two queue types,one center queue and N normal queues.Two-level means the center queue will be successive served aft...     

隧道区间水泵监控后备系统的研究

随着我国高速铁路建设的发展,采用水泵动力排水的铁路隧道逐步增多。水泵监控系统对于保障水泵正常工作和线路运行起着重要的支撑作用。通过总结现有水泵监控系统的实施情况,提出了一种提高系统可靠性的新型后备监控系统的设计方案,可供借鉴。     

无线电力传输技术初探

介绍无线电力传输技术的发展和目前主要的三种传输形式:通过电磁感应"磁耦合"进行短程传输;电能以电磁波"射频"或非辐射性谐振"磁耦合"等形式中程传输;电能以微波或激光形式远程传输.     

风电机组的功率曲线验证方法研究

功率曲线是风电机组发电能力的重要指标。本文讨论了功率曲线验证的必要性,并且提出了一种利用实测功率曲线与年发电量的相关性来考核厂家提供功率曲线是否达标的方法。以典型风电机组为例进行了研究分析。     

工程勘察行业现状和发展对策

经过改革开放四十多年，特别是我国加入WTO后多年的发展，我国工程勘察市场初步形成，工程勘察行业正逐步走向快速、健康的发展轨道。由于目前我国工程勘察市场尚不十分规范，工程勘察行业仍然存在一些值得思考和面对的问题。文章阐述了工程勘察行业发展阶段，分析了目前工程勘察行业的现状，提出了发展的思路和对策，同时，对工程勘察行业管理部门需加强的工作也提出了相关建议。