ON THE SUPERMODULUS EFFECT IN COMPOSITIORALLY MODULATED STRUCTURES

The departure of electronic distribution from local electrical neutrality and the additional energy due to such a departure in compositionally modulated structures are calculated using a simplified Thomas-Fermi equation. with the energy, we have derived the variation of the biaxial modulus with the modulation period. The result agrees at least qualitatively with the exprimental finding of a supermodulus effect in such structures.     

手性多齿胺膦钌配合物的设计合成和在芳香酮不对称氢化反应中的应用

简要介绍了多齿胺膦金属配合物的设计合成。这些多齿配合显示了单齿胺或膦金属配合物所不具有的丰富结构类型和特殊催化性质，合成和表征了含有结构类似的双亚胺双膦钌配合物（Ｒ，Ｒ）－３和双胺双膦钌配合物（Ｒ，Ｒ）－４。配合物（Ｒ，Ｒ）－４可作为多种芳香酮不对称氢化的手性催化剂，其光学收率最高达９７％。讨论了钌配合物的催化作用机理。     

Predictor control and suboptimal digital redesign for continuous-time systems with delayed input

This paper deals with the implementation of a predictor controllaw and the suboptimal digital redesign for a continuous-timeplant with a delayed input. It is shown that the closed-loopeigenvalues of the delayed system designed via a predicted-statefeedback controller are identical to those of the non-delayedsystem with the same gain matrix based on the non-predictedstate feedback. Thus, the well-developed design methods of linearquadratic regulators for continuous-time non-delayed systemscan be indirectly applied to delayed-input systems. Moreover,for practical implementation by digital computer, we derivea suboptimal digital redesign of the delayed-input system usingthe predictor control.     

METHANE OXIDATIVE COUPLING ON ThO_2/CaF_2CATALYST

The oxidative coupling of methane(OCM)over ThO_2/CaF_2 catalystwas investigated.The catalyst was found to be active and selective for OCMreaction.At 1153 K,the C_2~ yield was 19.9% with 61.7% C_2~ selectivityand 32.1% CH_4 conversion.XRD results indicated that F~-(?)O~(2-)exchangehappened between ThO_2 and CaF_2 phases.XPS and Raman results suggestedthat the active oxygen species were generated and suitable for OCM reactionover the catalyst.     

On the singular cases of the complex Routh algorithm for stability tests

The Original Routh table dealing with real polynomials is furtherinvestigated for complex polynominals. Based on the tabularform proposed by Parks for the complex polynomial with respectto the imaginary axis, modified procedures for directly treatingsingularities in the array are proposed. Also, new proceduresare developed for determining the respective orders of simpleand/or repeated roots lying on the imaginary axis. As a result,the situation of conditional stability or instability can bedistinguished by the criteria proposed in this paper.     

泥沙在动水中的沉淀运动(一)——圆球在流体中运动时所受的阻力

在河道动力学中,一般在讨论泥沙和水的相对速度时,都应用斯笃克斯公式。但是这样一个假定是没有经过严格证明的,它的正确性必须仔细地加以讨论。本文根据流体力学的基本理论讨论了一个小球在不均匀流场中运动时候的情况。在讨论的时候,我们引进了两个基本假定:(1)圆球直径和流场的线性尺度比较起来小得很多;(2)水和圆球的相对速度很小。有了这两个假定以后,我们就可以把运动方程式线性化,然后再利用拉普拉斯转换找出线性化以后的方程式的解。最后得到小球在非均匀流场中运动时所受到的阻力。     

Novel Synthesis of Nanometer Crystal-sized Zeolite NaY by Adding Lanthanum-containing Compounds

Nanometer-sized zeolite possesses many distinct advantages^[1,2] comparing with its commercially available micrometer-sized counterpart^[3], and receives much attention in recent years. In this work, a novel synthesis of nanometer-sized zeolite NaY is presented.     

Fault tolerant two-step quantum secure direct communication protocol against collective noises

This work proposes two fault tolerant quantum secure direct communication (QSDC) protocols which are robust against two kinds of collective noises: the collective-dephasing noises and the collective-rotation noises, respectively. The two QSDC protocols are constructed from four-qubit DF states which consist of two logical qubits. The receiver simply performs two Bell state measurements (rather than four-qubit joint measurements) to obtain the secret message. The protocols have qubit effciency twice that of ...     

双时间—温度格临函数的二元碰撞展开

应用李政道和杨振宁提出的二元碰撞展开法,对于有强短程排斥互作用的多粒子系发展了一种按图形计算双时间-温度格临函数的规则,其各级近似由二体散射相移的各次幂所表征。文中得出了玻色和费米统计情形的计算规则,并且研究了有凝聚相存在的玻色系统。本文主要讨论了单粒子格临函数的图形技术,但容易将它们推广应用于计算各种时间-温度格临函数。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.