Fabrication and characteristics of intrinsic Josephson junctions in Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>CaCu<Subscript>2</Subscript>O<Subscript>8+x</Subscript> single crystals

Mesa-structured intrinsic Jospehson junctions are fabricated in Bi2Sr2CaCu2O8 x single crystals.Typical current-voltage characteristics of intrinsic Josephson junctions are observed .which include multiple quasi-particle branches,surface junction with critical current lower than those of inner junctions.and subgap structures on quasi-particle branches,The corresponding physical explanations are also given .The energy gap voltage of the intrinsic Josephson junctions at 30 K is about 20mV Besides,The measured Ic-T relationship agrees quite well with the theoretical computations based on dx′-y′-wave superconductor.Our measured dI/dV-V relationship shows the V-shaped gap structure,obviously differing from the U-shaped gap structure of the s-wave superconductor.     

Si雪崩冷阴极的电子发射特性

采用离子注入和快速退火法可制备Ｓｉ浅ｐ－ｎ结阵列，通过真空清洁处理和铯氧激活后制成阵列式Ｓｉ浅ｐ－ｎ结雪崩冷阴极，其最高电子发射效率为１６％。本文介绍阵列式Ｓｉ雪崩冷阴极的制各方法，给出了Ｓｉ冷阴极的雪崩电子发射特性，讨论了影响发射稳定性的主要因素。     

Magnetic tunnel junctions (MTJs)

We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.     

具有诱导超导电性和自旋轨道耦合作用的半导体纳米线零偏压电导峰的研究

本文对具有诱导超导电性和自旋轨道耦合作用的半导体纳米线的微分电导谱的一些特性进行了详细的分析和研究. 通过对系统的微分电导谱与系统的各种可调控参量之间的关系进行详细的研究,发现在这类系统中存在两种不同类型的零偏压电导峰. 这两种零偏压电导峰具有不同的特点,相应地应由不同的物理机制所导致. 论文中的计算结果对澄清最近一些有争议性的理论问题有一定的理论参考意义.     

基于聚类遗传算法的梯级水利枢纽短期电力调度优化

针对标准遗传算法容易"早熟"的缺陷,提出聚类遗传算法;改进了选择算子和交叉算子,并利用Shubert多峰测试函数验证了聚类遗传算法的优势.引入水轮机组运行效率梯度变化因素提出改进变异算子,弥补了变异搜索过随机的缺陷.最后,将改进方式应用于三峡-葛洲坝梯级水利枢纽短期电力调度优化研究中,提出和构建了相应的优化模型以及机组组合启停和运行效率同步实现策略.实例优化结果表明:聚类遗传算法和改进变异算子能有效弥补"早熟"的缺陷,并能显著提高优化搜索效率,适用于梯级电站电力调度优化问题.优化得出的梯级电力调度方案可以满足设定目标和约束,并提高了梯级的发电效率.     

Character and fabrication of Al/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/Al tunnel junctions for qubit application

The superconductive Josephson junction is the key device for superconducting quantum computation. We have fabricated Al/Al2O3/Al tunnel junctions using a double angle evaporation method based on a suspended shadow mask. The Al2O3 junction barrier has been formed by introducing pure oxygen into the chamber during the fabrication process. We have adjusted exposure conditions by changing either the oxygen pressure or the oxidizing time during the formation of tunnel barriers to control the critical current density Jc and the junction specific resistance Rc. Measurements of the leakage in Al/Al2O3/Al tunnel junctions show that the devices are suitable for qubit applications.     

Intercellular communication in smooth muscle

The functioning of a group of cells as a tissue depends on intercellular communication; an example is the spread of action potentials through intestinal tissue resulting in synchronized contraction. Recent evidence for cell heterogeneity within smooth muscle tissues has renewed research into cell coupling.Electrical coupling is essential for propagation of action potentials in gastrointestinal smooth muscle.Metabolic coupling may be involved in generation of pacemaker activity. This review deals with the role of cell coupling in tissue function and some of the issues discussed are the relationship between electrical synchronization and gap junctions, metabolic coupling, and the role of interstitial cells of Cajal in coupling.     

试论物流系统的网络模式

1 物流的网络概念 从系统论的整体观念来看,可以将物流系统看作网络结构来进行研究,用流和积累等流机理来进一步掌握和控制网络。这种网络结构一般至少有一个源(发点,如油井、油库、车站、港口和计算中心的处理机等)和一个汇(收点,如炼油厂、另一个输送站和计算机通道等),网络中有多条支路,各支路的交点称为网络节点(如输油线上的阀门,计算机系统中的门电路等),每一对收发点间都有许多带方向的动态连线,以表示两点间的运动路线。相对静止的节点和动态的连线,构成一个系统网络。     

半导体PN结光电成像

该文描述半导体ＰＮ结，在不同偏置电压下，受强度调制光照射时，产生的光生电压的测量结果，并对ＰＮ结进行了静态（非工作状态）和动态（外加工作电压）光电成像。从理论上探讨了ＰＮ结光电成像的物理机制，得到了ＰＮ结光电成像的一般规律，由此为集成电路等半导体器件进行静态或动态光电成像检测及分析提供依据。     

“金属-Si原子链-金属”纳米结点电子输运性质的计算

运用密度泛函理论结合非平衡格林函数,以5个Si原子构成的直线链,及其与2个半无限长Au(100)-3×3电极相连接构成的金属-原子链-金属"三明治"模型为研究对象,对该结构的纳米级结点的电子输运进行了计算.结果表明,在两极距离dz=1.95~2.39nm的拉伸过程中,结点电导值有数量级的变化.当dz=2.03nm时,结点的结合能最小(ΔE=-5.43eV),结点结构最稳定,原子链内部Si—Si键长平均值为0.216nm,此时结点的电导为0.44 G0(G0=2e2/h).Si原子的px与py轨道电子形成π键,构成了电子经过结点的主要传输通道;随着正负外偏电压的增大,电导减小,且成对称变化,其I-U曲线表现出非线性特征.