一种OLS/OOC二维光正交码的构造与性能分析

利用不同的序列作为波长跳频序列和时间扩频序列可以构造出不同的二维光正交码在众多文献中已有所报道.在经过正交拉丁方(OLS)与跳频序列的相关性研究之后.做了以下主要工作:首先,将正交拉丁方(OLS)序列作为波长跳频序列,结合一维时间扩频序列(OOC),构造了一种OLS/OOC二维光正交码.然后,本文对构造的OLS/OOC进行了多种性能仿真和分析.相对于PC/OOC、OCFHC/OOC等二维光正交码而言,OLS/OOC的波长数并不局限于素数,更能充分利用MWOCDMA系统中的有效波长数.仿真和分析表明:码字具有很好的相关性能,码字容量直逼理论极限,为一种渐近最优二维光正交码.     

周期竞争Lotka-Volterra系统的持久性和灭绝性

研究周期竞争Lotka-Volterra系统,改进了两种群竞争排斥的充分条件,并且把竞争排斥原理推广到多种群的情形,给出了多种群系统中种群持久和灭绝的充分条件.     

逆Weibull分布随机变量的随机比较(英文)

研究了两个相互独立的逆Weibull分布随机变量间的随机序,似然比序,危险率序以及凸序之间的相互关系,给出了两个相互独立但不同分布的随机变量满足各种随机序时其分布所含参数间的相应关系.也给出了两组相互独立但不同分布的随机变量极值间在一般随机序下的大小关系.     

Appearance of autocatalysis in the production of molecular hydrogen by a photoreaction on semiconductor heterojunctions

The photocatalytic evolution of H₂ from ethanol and aqueous solutions of Na₂SO₃ and Na₂S by suspensions of CdS/Cu²⁺ and CdS/Bi³⁺ microheterojunctions has been investigated. The appearance of autocatalysis has been obtained, attributed to a lowering of the energy barrier of the reaction; it is caused by a change in the work function of an electron from the palladium co-catalyst, due to its saturation by the product (hydrogen).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 5, pp. 435–440, September–October, 1993.     

Theory of the tunnel effect in a superconductor

The tunnel hamiltonian is used to show that the tunnel current in a contact between two normal or superconducting metals is expressed utilizing the densities of the states near the Fermi surface. The formula is correct for any temperature and for a superconductor with any type of condensation, and also for any singularity in the spectrum of the normal or superconducting metal localized near the Fermi surface (E ).I am indebted to M. I. Kaganov for a discussion.     

“Hybrid” photocatalytic systems for production of molecular hydrogen

It has been shown on the example of semiconductor (CdS, TiO₂) and metal complex (solvate complexes (V(III), Eu(III), Zr(IV)) photocatalysts that they can form a single photocatalytic system that is characterized by higher efficiency in the direction of the formation of hydrogen from alcohol-water solutions than the individual substances. Successful functioning of such a hybrid photocatalytic system is possible if the principle of energy correspondence is satisfied: the potential of the conduction zone of the semiconductor must be more negative than the redox potential of the Meⁿ⁺/Me^(n–1)+ pair. In this case a photogenerated electron of the conduction zone is accepted by a metal ion Meⁿ⁺ and, thus, the electron-hole recombination process is suppressed. The resulting reduced form of the metal Me^(n–1)+ in the presence of metallic palladium decomposes the protonated molecules of water with the formation of H₂.Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 25, No. 4, pp. 452–459, July–August, 1989.     

高举“鞍钢宪法”旗帜 坚持“工业学大庆”道路

在毛主席革命路线指引下,旅大市工业战线各级党委,高举“鞍钢宪法”旗帜,坚持“工业学大庆”,全心全意地依靠工人阶级,使群众性的技术革新和技术改造运动不断向前发展。1971年以来,旅大市共实现技术革新三万六千多项,改造老设备和自制专用设备一万五千多台,建成了自动线、半自动线和流水线一百六十多条,并取得了不少新成果,其中包括四千马力内燃机车、二万四千吨油轮、二百二十五吨大型冶金吊车、高效组合机床、新型柴油机、十九吋电视显象管等。初步改变了旅大老工业城市技术落后的面貌,加快了工业建设的步伐。旅大市去年工业总产值比1973年增长11％,比1949年建国当时增长23倍。就工业产值来说,今天的一个旅大,等于文化大革命前两个半旅大。     

Excitonic “superfluidity” in low-dimensional crystals

The “superfluid” properties of layered metallic crystals comprising conducting sheets of electrons and holes are predicted. The excitonic pairing in such anisotropic system manifests itself in alternating diamagnetic response to small longitudinal fields and, at sufficiently high fields (H| and E⊥), in the oscillating Josephson currents flowing in the direction perpendicular to the sheets.     

大气边界层中湍流场的团块结构

本文分析了从声雷达探测中发现的团块回波,它具有明显的边界,其形状是不规则的。回波强度在团块内部也是不均匀的,大多数团块具有扁平特点。团块回波一般出现在夜间、小风、稳定层结,并经常和一定的天气过程(如雷暴、降水等)相联系。根据声波在湍流大气中的传输理论,可以认为团块回波反映了边界层大气存在着密度不均匀的气块。这种气块的存在,对于波的传输、物理量(如动量、水汽、热量等)的输送、污染物的扩散、以及湍流化学等问题都会产生一定的影响。     

Mechanism of the combined reaction of butyl isocyanate and methanol with aerosil

The joint sorption of butyl isocyanate and methanol vapors on pretreated Aerosil has been studied by infrared spectroscopy. We show that free hydroxyl radicals participate in the process to form a urethane chemically combined with the adsorbent. Methanol acts as a catalyst. The mechanism of the reaction is discussed.