Maximally equidistributed pseudorandom number generators via linear output transformations

This article discusses construction of maximally equidistributed (ME) linear feedback shift register generators by using linear output transformations. We introduce a new strategy to find linear output transformations attaining the ME property, and apply it to the WELL generators and the Mersenne Twister. As a result, we found a modified version of the WELL generators with the ME property, having fewer operations than the original ME WELL generators. We also found a ME Mersenne Twister which is faster than the WELL generators with a period of 2¹⁹⁹³⁷−1$2^{19937}-1$ on some platforms. The C codes of the obtained generators are available at http://www3.ocn.ne.jp/∼harase/megenerators.html.     

Limitations of nonlinear discrete periodic control for disturbance attenuation and robust stabilization

This paper presents a performance analysis of nonlinear periodically time-varying discrete controllers acting upon a linear time-invariant discrete plant. Time-invariant controllers are distinguished from strictly periodically time-varying controllers. For a given nonlinear periodic controller, a time-invariant controller is constructed. Necessary and sufficient conditions are given under which the time-invariant controller gives strictly better control performance than the time-invariant controller from which it was obtained, for the attenuation of l_p exogenous disturbances and the robust stabilization of l_p unstructured perturbations, for all p[1,∞].     

钴钇掺杂（Ba,Sr）TiO_3基介电陶瓷的制备与性能研究

采用二次固相反应法制备Ba0.7Sr0.3TiO3介电陶瓷,研究了掺杂钴、钇离子对钛酸锶钡介电性能的影响。结果表明,陶瓷样品Y3＋、Co3＋的最佳掺杂浓度分别为0.04mol%和0.05mol%,最佳烧结温度为1340℃,样品的相对介电常数为4200,介电损耗（tanδ）为0.005。样品的结构为四方晶系,P4mm空间群。获得了高介电常数、低损耗的Ba0.7Sr0.3TiO3介电陶瓷。     

AZ31+Y+Sr镁合金板超塑成形中空洞演化

针对添加了Y和Sr元素双辊连铸连轧(TRC)AZ31镁合金板材气胀成形过程中空洞形成进行了研究,采用了双辊连铸连轧工艺制备出1 mm厚的AZ31和AZ31+Y+Sr板材,并进行了气胀成形实验.通过宏观测量与金相观察对胀形件进行分析,结果表明:连铸连轧工艺能够有效细化晶粒,在同等温度条件下,添加了Y和Sr元素的AZ31板材其超塑性能比普通双辊连铸连轧AZ31板材有显著提高;胀形件顶部比球面的空洞尺寸大、数量多,空洞的形成经过了形核、长大和聚合三个阶段,最终导致材料的断裂.     

Changes of copper location in CuY zeolites induced by preparation methods

The location of transition ions in copper- and copper-zinc-loaded Y type zeolites prepared by different procedures has been studied by temperature-programmed reduction, infrared spectroscopy of CO adsorbed on pretreated samples and X-ray photoelectron spectroscopy. Samples outgassed at 673 K showed Cu⁺ species due likely to reduction of Cu²⁺ ions under vacuum. Over exchanged CuY zeolites copper species in exchange sites were detected, while an impregnated sample exhibited bands of CO adsorbed on both Cu²⁺ and Cu⁺ ions developed at the surface of CuO crystals, and small proportions of Cu⁺ ions located in accessible exchange sites S_II and Sn_II. Similar findings were observed in Zn- and Cu-exchanged zeolites although the relative proportion of Cu in S_I positions was decreased due to competition between Cu²⁺ and Zn²⁺ ions. Samples reduced in hydrogen at 523 K showed the appearance of Cu⁰ species in impregnated samples, whereas Cu⁺ dominated in the exchanged counterparts. Reduction at 598 K led to substantial changes in Cu-exchanged samples in water. The proportion of Cu⁺ species decreased by reduction to Cu⁰ and simultaneously migration to Cu⁺ to S_II sites occurred. While Cu²⁺ or Cu⁺ were found on outgassed samples, only Cu⁰ and intrazeolite Cu⁺ were observed after H₂-reduction at 623 K. Changes in copper exposure as a function of sample pretreatments were also revealed by X-ray photoelectron spectroscopy.     

Effects of Y concentration on luminescence properties of PbWO4 single crystals

The effects of Y³⁺ doping at different concentration on the luminescnece properties of PbWO₄ crystals have been investigated by means of Fourier transform infrared (FT-IR) spectrum, optical transmission, thermoluminescence (TL), X-ray excited luminescence (XEL), photoluminescence (PL) under excitation of UV light and light yield measurements. The series PbWO₄:Y crystal samples were grown by modified Bridgman method and the concentration of Y³⁺ in the melt was in the range of 0–1.0 mol%. The slight blue-shift and evident red-shift of the absorption edge in PbWO₄ crystal were observed at low and heavy doping concentration, respectively. TL peaks in the range of from room temperature to 250 °C disappeared after the doping with Y³⁺. With the increase of doping concentration, the luminescence intensity in the XEL and PL spectra was found to decrease accordingly, especially in the case of heavy doping. The measuring results demonstrate that Y³⁺ doping concentration below 100 ppm in the crystal seems to be the best for optimizing the optical and scintillation properties of the material. The mechanism of Y³⁺ doping concentration influence on luminescence was also discussed in this paper.     

Characterization of (Y,Gd) BxV1-xO4-x:Eu Phosphor Prepared by Coprecipitation Reaction

White body-color (Y, Gd)BxV1- xO4-x :Eu3 phosphors were prepared by coprecipitation reaction. Under VUV excitation at 147 nm, the red emission colorimetric purity of (Y, Gd)BxV1- xO4-x :Eu3 phosphor is much better than that of commercial PDP (plasma display panels) phosphor (Y, Gd)BO3:Eu3 . But its relative emission intensity is only about 90% of the commercial phosphor.     

低温燃烧法制备Y2O3:Eu3+纳米材料的研究进展

低温燃烧法是制备氧化物纳米材料的一种很有应用前景的新方法,该法工艺简单、安全、省时、节能.Y2O3:Eu3 是一种重要的红色发光材料.阐述了低温燃烧法合成工艺的优点,其制备纳米材料Y2O3:Eu3 的特点,以及用该方法制备的纳米材料Y2O3:Eu3 的发光性能的研究进展.     

纳米粉掺杂的Y2O3-ZrO2陶瓷的制备

采用纳米粉掺杂烧结制备了Y2O3-ZrO2陶瓷。测试发现，纳米粉的掺入在一定程度上可以使烧结体的密度和硬度得到提高。SEM和EDS分析表明，烧结体表面比较平滑，元素分布比较均匀，有较小的气孔存在。     

店坪Y,d11牵引站空载运行分析

系统地分析了电气化铁路Y ,d11牵引站的空载运行。得出由于牵引站低压侧两相 (a、c)不对称无功固定补偿所引起的牵引站高压侧两相A、C过补偿 ,B相欠补偿和牵引站A、C相与三相对称电力系统的有功功率循环。提出了一种新型Y ,d11牵引站三相对称无功固定补偿实现方案