Investigation of the size effect on optical properties of polycrystalline Ge deposition by pulse laser deposition

The size effect of optical properties of the polycrystalline Ge/Si films prepared by pulse laser deposition (PLD) is investigated by photoluminescence (PL) and photocurrent (PC) spectra. The size of Ge nanocrystals is precisely controlled by the pulsed deposition time and then observed by the atomic force microscopy (AFM). The average size of Ge nanocrystals is about 2, 5 and 25 nm for 1, 2 and 3 min deposited sample, respectively. The size effect on optical properties of Ge nanocrystals has been analyzed by photoluminescence (PL) and photocurrent (PC) spectra. The PL peaks shift from 0.799 eV for 1 min to 0.762 eV for 3 mins; at the same time, the photocurrent peaks of the films sharply changes from 0.781 eV to 0.749 eV, the shifts of PL and PC are contributed to the quantum size effect of Ge nanocrystals.     

Three-dimensional space-vector modulation algorithm for four-leg multilevel converters using abc coordinates

In this paper, a novel three-dimensional (3-D) space-vector algorithm for four-leg multilevel converters is presented. It can be applied to active power filters or neutral-current compensator applications for mitigating harmonics and zero-sequence components using abc coordinates (referred from now on this paper as natural coordinates). This technique greatly simplifies the selection of the 3-D region where a given voltage vector is supposed to be found. Compared to a three-level modulation algorithm for three-leg multilevel converters, this algorithm does not increase its complexity and the calculations of the active vectors with the corresponding switching time that generate the reference voltage vector. In addition, the low-computational cost of the proposed algorithm is always the same and it is independent of the number of levels of the converter.     

基于测度贴近度的电子剪切散斑轮胎检测

本文把测度贴近度的概念引进到电子剪切散斑检测中,提出了一种基于测度贴近度的条纹形成算法。该算法大大地消除了条纹可见度对光照强度的依赖,提高了电子剪切散斑无损检测对工业环境的适应性,并且该算法可以在条纹产生的同时对其进行滤波,减轻了后续工作。本文从数学分析和实验两个角度证实了该算法的以上特点。     

加工配送，钢铁企业营销新战略

加工配送是当前一种新型的钢材物流服务方式，在营销战略方面已经越来越受到钢铁企业的高度重视。对当前国内钢材加工配送的市场状况的成因进行了分析，对部分生产企业的基本特点进行了描述，并对钢材加工配送未来的发展方向进行了阐述。     

液态金属离子源发射系统电场的模拟分析

发射系统是液态金属离子源的关键部件之一，它的性能的优劣直接影响到整个离子源的工作稳定性和可靠性。因而对其发射系统进行仿真分析，可以很好地指导液态金属离子源的设计制造。本文采用国际上重视的动态喷流柱模型，利用模拟电荷法对液态金属离子源的发射系统的电场进行了计算分析，画出了发射尖端电场强度随不同参数变化的曲线，得出发射尖端表面场强与球冠半径、发射体突出臂长度密切相关，而与引出电极的结构关系甚小的结论，因此液态金属离子源发射特性（如角电流强度）的改善，必须在发射尖的设计制作上下功夫。从而为液态金属离子源的设计提供了一个有效的辅助工具。     

Preparation and characterization of Ni/Co bimetallic nano-clusters

Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions including the type and concentration of protective agent, feeding order and the pH of the solution that influence the average particle size have been studied in detail. Transmission electron microscopy (TEM) indicates that the shape of those bimetallic nano-cluster particles is spheroid. The alloy structure has been shown by X-ray powder diffraction (XRD). The X-ray photoelectron spectroscopic (XPS) data have confirmed that the nickel and cobalt in the bimetallic nano-clusters are in the zero-valence state.     

配料车间Modbus plus网络控制系统设计

本文简要介绍了Modbus plus总线协议，分析了基于Modbus plus总线协议的某炼铁厂配料车间，配料闭环现场总线控制系统的网络设计。     

Flow Simulation and Optimization of Plasma Reactors for Coal Gasification

This paper reports a 3-d numerical simulation system to analyze the complicated flow in plasma reactors for coal gasification, which involve complex chemical reaction, two-phase flow and plasma effect. On the basis of analytic results, the distribution of the density, tempera-ture and components‘ concentration are obtained and a different plasma reactor configuration is proposed to optimize the flow parameters. The numerical simulation results show an improved conversion ratio of the coal gasification. Different kinds of chemical reaction models are used to simulate the complex flow inside the reactor. It can be concluded that the numerical simulation system can be very useful for the design and optimization of the plasma reactor.     

低压断路器的新材料和新工艺应用

对引进德国西门子公司技术制造的3WE系列断路器在新材料和新工艺应用方面与国内此领域传统使用的材料和工艺进行了分析、对比。期望能对国内同行在产品设计、制造和改进过程中起到借鉴和参考作用。