Electrical properties of W/Si interfaces with embedded Ge/Si islands

In this work, we investigated electrical and morphological properties of W/p-type Si Schottky diodes with intentional inhomogeneities introduced by macroscopic Ge-islands embedded beneath the interface. The Si-cap layer thickness (or the island-distance to the interface) was progressively reduced by successive chemical etching cycles. Electrical characterizations were achieved through reverse current–voltage (I–V) at room temperature and forward I–V measurements as a function of the temperature. In parallel, Rutherford backscattering spectroscopy analyses were performed to follow the Si-cap/Ge islands chemical thinning down with increasing the number of etching cycles. In addition, the comparison of topographical and electrical properties of the etched silicon-cap layer was carried out by conductive atomic force microscopy analyses with a nanometer-scale resolution. Our results indicate that the areas on the top of islands exhibit lower resistance than those which covered the wetting layer. This lateral variation of resistance at the surface of the semiconductor may correspond to Schottky barrier height inhomogeneities observed on broad area I–V characteristics of Schottky contacts.     

Correlation of microstructure with electrical behavior of Ti/GaN schottky contacts

We correlate structural and electrical characteristics of as-deposited and low-temperature annealed Ti contacts on GaN. Temperature dependent currentvoltage measurements are used to determine the effective barrier heights of the respective contacts, while high-resolution transmission electron microscopy is utilized for structural characterization. As-deposited Ti contacts are slightly rectifying with an effective barrier height of ∼200 meV. After annealing at 230°C, the barrier height increases to values of ∼450 meV. A similar behavior of Schottky contacts with more strongly rectifying diodes upon low-temperature annealing is observed for Zr metal contacts on GaN. As-deposited Ti already forms a thin TiN layer at the GaN interface. After annealing at 230°C, the average thickness and the distribution of TiN grains remain practically unchanged, but the interface with GaN roughens. We correlate the observed barrier height changes with interface roughness and phase formation and we discuss the results in terms of interface damage and the Schottky-Mott theory.     

露天矿汽车运输功与台阶高度的关系

以１８ｍ台阶和１２ｍ台阶的露天为例，分析了台阶高度与矿岩势能、矿岩运距及汽车运行速度的关系，认为单一汽车运输的露天矿，随着台阶高度的增加，汽车运输功有减小的趋势。     

向家坝水电站地下厂房变顶高尾水系统研究

为了满足电站的调节保证要求，减小地下洞室群的规模，向家坝水电站地下厂房采用了特殊的尾水系统布置方案，即变顶高尾水洞方案，取消了尾水调压室。在研究水电站变顶高尾水洞基本工作原理的基础上，提出了向家坝水电站右岸地下厂房变顶高尾水洞布置方案研究的基本思路和具体步骤，论证了采用变顶高尾水洞方案的可行性和合理性。     

条带开采覆岩破坏高度探测与分析

根据钻孔漏失量法和彩色钻孔观测资料,对条带开采覆岩破坏高度进行了分析,提出条带开采条件下覆岩破坏规律,对条带开采在水体下采煤领域的应用有一定指导作用。     

钢筋混凝土梁板有效高度及截面设计

就混凝土梁板有效高度以及经济截面设计进行了分析 ,并提出其有效高度与经济配筋率的核心范围 ,指明只有在该核心范围内才能保证工程安全 ,全面达到降低工程造价 ,提高经济效益的目的。     

雨蓬网架结构设计

本文结合工程实践，介绍了变高度正放四角锥网架应用于大跨度悬挑雨蓬时的结构形式、网格数量、网架高度、内力计算和截面设计的确定方法，提出了新的边界支承条件和支座构造形式。     

Effect of probe size on heat transfer at the wall in circulating fluidized beds

An experimental investigation was made to study the effect of vertical probe height on heat transfer at the wall in circulating fluidized beds. Experiments were conducted in a 100 mm internal diameter, 5.15 m tall circulating fluidized bed. Four probes having 85, 127.5, 170 and 255 mm heights were tested. Heat transfer measurements covered a range of superficial velocity from 7.2 to 12.5 m/s and a range of suspension density from 25 to 68 kg/m³. The results were compared with those of other investigators. An empirical correlation incorporating the dimensionless probe height and the particle Nusselt number and Reynolds number has been suggested.     

巨型冷却塔进风口高度模拟分析

根据气水两相间热质传递原理,用Fluent数值计算软件建立了AP1000核电机组用20 000 m2淋水面积巨型冷却塔的三维计算模型.对塔体进风口高度的不同取值进行了模拟与计算,综合分析了不同环境侧风对塔内流场、出塔水温、进塔风量的影响,优化了210 m巨型冷却塔的进风口高度结构设计.     

预制混凝土拱涵地震响应分析

首先建立拱涵二维有限差分模型,对拱涵的安装与路堤的填筑过程进行模拟,并得到拱涵与填土体系受力的初始状态;然后对拱涵进行时程分析,探究拱涵在地震作用下的位移与应力响应规律;最后着重论述填土高度、地震加速度以及地震波传播角度对拱涵地震动力响应的影响,并分析混凝土预制拱涵在地震作用下的薄弱位置。结果表明：随着填土高度的增加,拱顶与基底之间水平相对位移逐渐增大,拱涵各个接触面的内力在静态内力的基础上显著非线性增大;拱涵的各个接触面的内力对峰值加速度的改变较敏感;随着地震波传播角度的增大,拱顶与基底水平相对位移将减小,拱涵的内力响应也逐渐减小。