An index structure supporting rule activation in pervasive applications

World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...     

磷酸盐玻璃中稀土离子的发光浓度效应研究

磷酸盐玻璃中稀土离子的发光浓度效应研究王民权，马立新，樊先平（浙江大学材料科学与工程系３１００２７）（南京航空航天大学）ＳｔｕｄｙｏｎＣｏｎｃｅｎｔｒａｔｉｏｎＥｆｆｅｃｔｓｏｆＲａｒｅＥａｒｔｈＩｏｎｓｉｎＰｈｏｓｐｈａｔｅＧｌａｓｓｅｓ￥Ｗａｎｇ...     

Luminescence Characterization of Mg Doped Y2O2S:Ti Long Afterglow Phosphor

Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors decrease gradually with increasing Mg2 ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5 ℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 ℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S:Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2 ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-xMgxO2S:0.06Ti phosphor.     

逆变弧焊机中IGBT的防护

本文介绍了ＩＧＢＴ逆变弧焊机中的过电压、过电流保护电路，包括外部过电压、内部过电压、输出过电流和ＩＧＢＴ器件过电流的防护措施。文中还就驱动电路的应用进行了讨论，以提高ＩＧＢＴ器件的使用可靠性。     

模具计算机集成制造体系结构的研究

本文对ＣＩＭＳ技术在模具制造业的应用进行了分析,提出了适合于国内模具制造企业的ＣＩＭＳ体系结构及开发思想,方法。     

膨润土尾矿作PVC塑料填料的研究

研究了膨润土尾矿的比表面积、添加量及偶联剂表面改性处理对其作为PVC塑料填料时的力学性能和流变性能的影响。结果表明,膨润土尾矿作填料的PVC试样,拉伸强度优于重质CaCO_3,为填料的试样,冲击强度和流动性能则有所下降。钛酸酯作偶联剂有利于提高填充试样的冲击强度。但对拉伸强度无明显效果。膨润土尾矿的添加量约20份时,试样的力学性能最佳。     

硅酸盐熟料-煤矸石/粉煤灰混合水泥水化模型研究

对两种不同3CaO·SiO_2(C_3S)含量的硅酸盐水泥和分别掺有30%(质量分数,下同)煤矸石和30%粉煤灰的混合水泥中水化产物含量变化和形态进行了研究,建立了水化产物量变模型和水化产物形态模型,分析了模型的主要特征和意义。相同龄期,高C_3S硅酸盐水泥比低C_3S硅酸盐水泥生成更多的水化硅酸钙(calcium silicate hydrate,CSH)凝胶和氢氧化钙。含混合材的水泥水化时,CSH凝胶在水化早期和后期有两个增长幅度较大的阶段,并且1年后形成的CSH凝胶量与纯硅酸盐水泥的相当。水泥水化产物与混合材的二次水化反应较慢,研究掺有混合材水泥更长龄期的水化产物含量及结构变化,将有助于理解混合材对水泥性能的作用机理。     

浅谈改善不饱和聚酯涂料气干性的方法

叙述了不饱和聚酯涂料的成膜机理。列举了目前改善不饱和聚酯底漆干性的主要方法,如薄膜遮盖法、石蜡覆盖法、改变树脂中可共聚的单体、添加醋酸丁酸纤维素、在不饱和聚酯中引入气干性基团等。并对其利弊作了简要的分析。     

二氧化碳低温泵密封结构的改进措施

针对一台二氧化碳泵密封泄漏严重的问题,分析了密封失效的原因,提供了解决密封泄漏问题的方法,从根本上解决了该泵的泄漏问题,从而提高了泵密封的性能和使用寿命,提高了设备运行的可靠性,取得了良好的经济效益。     

Sonochemical synthesis of core/Shell structured CdS/TiO<Subscript>2</Subscript> nanocrystals composites

A simple sonochemical route for the surface coating of titanium dioxide on cadmium sulfide nanocrystal was reported. After 2 h ultrasonic irradiation treatment, the mixture of CdS nanocrystals and tetrabutyl titanate in an aqueous medium yielded CdS/TiO₂ nanocrystals composites with core/shell structure. The thickness of TiO₂ layer with smooth interface could be easily controlled via changing the concentration of the precursors and the time of irradiation. The core/shell nanocrysrals were characterized by X-ray diffraction, transmission electron microscope and UV-vis spectrometry techniques. The prepared semiconductor composites with particular band structure present appealing properties especially in photochemical activity.