Optical Properties of One-dimensional Three-component Photonic Band Gap Structure

1　IntroductionMaterialswithPhotonicBandGaps (PBG’s)havebeenwidelystudiedboththeoreticallyandex perimentallyinthepastfew years[1～ 4] .Theexis tenceofgaps,which prohibitthepropagationofelectromagnetic (EM )wavesinacertainrangeoffrequencies,canhavesignificantimpactsbothinsci enceandtechnology .Manypracticalapplicationsofthesestructureshavebeensuggestedanddemon strated ,suchasPhotonicCrystal (PC)microcavi ties[5] ,infraredPC[6] ,PClens[7] ,suppressingspontaneousemission ,manipulatinglight…     

图形点阵式液晶显示器MSP-G320240在高速处理器DSP中的应用

介绍了内置SD1335控制器的图形液晶显示器MSP-G320240的工作原理及应用方法，给出了MSP-G320240液晶显示器同DSP的简单接口电路，同时给出了相应的液晶显示器的初始化和清显示区的具体程序。     

蜡晶形态结构对原油降凝的影响

 采用偏光显微镜观察了不同条件下蜡晶的形态变化，对蜡结晶过程中的结构、分布状态和生长规律进行了深入的研究，采用气相色谱分析了用52#、62#、80#蜡配制的模拟油中蜡的碳数分布，考察了凝点与蜡含量之间的变化规律，以及沥青质、胶质和大分子降凝剂(PPD)对模拟油降凝、降粘的影响，为改善原油流动性提供理论依据。实验结果表明，蜡晶的微观形态结构、蜡在油中的溶解性能以及降凝剂的降凝作用与模拟油中蜡的碳数分布密切相关，只有当降凝剂分子结构与油中蜡的结构匹配时，才能达到理想的降凝效果。通过实验确定了模拟油降凝时的临界蜡含量为40%（质量分数），大于该临界值后，凝点随着蜡含量的变化幅度将大大降低。     

P(DBF-VA)型柴油低温流动性改进剂的研制

针对新疆地产柴油蜡含量较高的特点,以游离基聚合法合成了富马酸双链混合酯和醋酸乙烯酯共聚物型[P(DBF-VA)]柴油低温流动改进剂,利用正交实验研究了单体配比,引发剂用量,溶剂用量,聚合温度对聚合物降冷滤效果的影响。共聚物用IR进行表征,利用XRD初步探讨了该降凝剂的降凝机理。结果表明:该剂能使吐哈—10~#、0~#柴油冷滤点降低10℃和7℃;使独山子0~#柴油冷滤点下降12℃;使石化0~#柴油冷滤点下降8℃;使克拉玛依0~#柴油的冷滤点下降8℃。     

诱导水解法制备微细高分散金红石型二氧化钛

采用加热TiCl4稀溶液的方式,制备晶种,将其导入一定浓度的TiCl4溶液中进行诱导水解。所得的偏钛酸经干燥、煅烧后得到分散性好,D50为1 mm以下,金红石含量为≥95%的高纯TiO2,可用于生产PTC热敏电阻等铁电陶瓷。     

Nd3+:Y0.5Gd0.5VO4晶体生长和基本特性

Nd^3 :Y0.5Gd0.5VO4晶体作为一种新的激光材料，可以用中频感应加热提拉法生长。X射线粉末衍射分析表明它的结构与Nd^3 :YVO4晶体结构相同，它的晶格常数介于YVO4和NdVO4晶格常数之间。用ICP光谱法测定晶体中Nd^3 含量为0．8at％，分凝系数为0．8，与Nd^3 :GdVO4晶体中Nd^3 的分凝系数0．78相当；用称重法测定其密度为5．00g／cm^3；用稳态纵向热流法测出其室温热导率为12．5W／mK。实验表明Nd^3 :Y0.5Gd0.5VO4晶体有希望作为高功率ID泵浦激光晶体材料。     

基于MODBUS协议的激光雕刻切割系统HMI人机交互设备

近年来,国内激光雕刻切割控制器技术发展迅速,基于PC的传统控制器已相当成熟.为了显著提高工业生产效率,适应工业生产规模扩张的需要以及工业对系统稳定性要求的提高,目前国内几家专业运动控制器厂家已经实现了激光雕刻切割控制器的完全脱机运行.本文针对脱机控制器的需要设计一款人机交互设备,该设备采用AT89C55WD单片机为主控制器,采用标准的MODBUS协议实现HMI与脱机控制器的可靠通讯.     

Precision measurement of energy and position resolutions of the BTeV electromagnetic calorimeter prototype

The energy dependence of the energy and position resolutions of the electromagnetic calorimeter prototype made of lead tungstate crystals produced in Bogoroditsk (Russia) and Shanghai (China) is presented. These measurements were carried out at the Protvino accelerator using a 1–45 GeV electron beam. The crystals were coupled to photomultiplier tubes. The dependence of energy and position resolutions on different factors as well as the measured electromagnetic shower lateral profile are presented.     

Structural changes in isothermal crystallization process of polyoxymethylene investigated by time-resolved FTIR, SAXS and WAXS measurements

Structural evolution in the isothermal crystallization process of polyoxymethylene from the molten state has been investigated by carrying out the time-resolved measurements of infrared spectra and synchrotron small angle X-ray scattering (SAXS) and wide angle X-ray scattering. In case of isothermal crystallization at 130 °C, for example, the infrared bands intrinsic of folded chain crystal (FCC) morphology appeared at first, and then the bands of extended chain crystal (ECC) morphology were detected with time delay of ca. 150 s. In the SAXS experiment at 130 °C, the lamellar stacking structure of the long period of ca. 15 nm was observed at first, which changed rapidly to ca. 12 nm in a short time. The SAXS peak with the long period of ca. 6 nm started to appear with a time delay of ca. 150 s after the initial lamellae appeared and coexisted with the initially-observed 12 nm peak. Judging from the timing to detect these characteristic infrared and SAXS signals, a good correspondence was found to exist between the stacked lamellar structure of 12 nm long period and FCC morphology and between the structure of 6 nm long period and ECC morphology. The quantitative analysis was made for the SAXS data on the basis of the lamellar insertion model combined with the paracrystalline theory of the second-kind of disorder. The following structural evolution was deduced from all these results. Immediately after the temperature jump from the melt to 130 °C, the stacked lamellar structure of FCC morphology was generated at first. New lamellae were formed from the amorphous region in between the originally-existing lamellae about 150 s later, where the random chain segments bridging the adjacent lamellae were extended to form the taut tie chains, giving infrared bands of ECC morphology. This inserted lamellar structure of 6 nm long period coexisted at a population of ca. 6% with the initially-formed lamellar stacking structure of 12 nm long period. When the experiment was made at 150 °C, only the formation of stacked lamellar structure of FCC morphology was observed and the insertion of new lamella did not occur.     

AFM observation of polyethylene single crystals: selective handedness of screw dislocations in a chair type

The three-dimensional morphology of polyethylene single crystals grown from dilute solution has been examined by atomic force microscopy. Single crystals were deposited on a soft ground of aqueous solution of poly(vinyl alcohol) (PVA) to avoid the collapse of thin lamellar crystals with thickness of 10 nm. The observation of single crystals on dried PVA clarifies the morphology of a chair type crystal as well as well-known hollow pyramidal type. It has been confirmed that the screw dislocations in the chair type follow a selection rule of the handedness in a manner to relieve the distortion in the chair type.