A novel cyclic process using CaSO4/CaS pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants: Part II. Hydrogen reduction of calcium-sulfate pellets to calcium sulfide

The reduction of calcium sulfate to produce calcium sulfide is a part of the cyclic process for converting sulfur dioxide to elemental sulfur that is described in Part I. The kinetics of the hydrogen reduction of nickel-catalyzed calcium-sulfate pellets were investigated using a thermogravimetric analysis (TGA) technique at reaction temperatures between 1023 and 1088 K and hydrogen partial pressures between 12.9 and 86.1 kPa. The reactivity of nickel-catalyzed calcium-sulfate pellets was demonstrated by the conversion of 70 pct fresh nickel-catalyzed calcium sulfate to calcium sulfide in 20 minutes at 1073 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after ten cycles of reactions and regenerations. This observed characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The nucleation and growth rate expression was found to be useful in describing the kinetics of the reaction, which had an activation energy of about 167 kJ/mol (∼40 kcal/mol) in all reaction cycles except for the first regenerated samples that were lower at 146 kJ/mol (35 kcal/mol). The reaction order with respect to hydrogen partial pressure was 0.22 in all cycles with the exception of the first regenerated sample for which it was 0.37.     

Effects of extended dislocations on charge distribution in GaN epilayer

We have investigated the effect of extended dislocations (0.5-3 μm) on charge distribution in GaN epilayer grown by metalorganic chemical vapor deposition on (0001) sapphire using atomic force microscopy (AFM) and scanning surface potential microscopy (SSPM). It has been observed for the surface at the extended dislocations present in undoped GaN film to be negatively charged showing 0.04-0.2 V higher potential relative to regions that contain no dislocations. In addition to the higher potential at the dislocation core, the surrounding surfaces, including the edge of the dislocations, are also negatively charged in a symmetric way around the dislocations revealing crater-shaped higher potential regions (∼0.04 V) relative to surrounding dislocation-free area. The experimental results show that the protrusion-type of dislocation is also negatively charged and its potential is dependent on the size of dislocation.     

基于公钥加密算法和PPCT动态图编码的软件指纹方案

提出了一种综合PPCT动态图编码方法和椭圆曲线加密算法的软件指纹方案,该方案将公钥加密技术和软件水印技术综合应用于软件版权的保护和验证过程中,充分利用两者的优势,具有安全性高和抗恶意篡改能力强的特点.     

首钢烧结配加扬地粉试验研究

介绍了首钢原料条件下配加扬地粉对烧结生产影响的实验室研究.随着扬地粉配入量的增加,烧结矿转鼓强度、成品率改善,燃耗有少量上升,利用系数增加,低温还原粉化指数变差.研究结果表明:在首钢目前条件下,配入10%～20%的扬地粉是可行的.二烧车间进行了扬地粉工业试验,其最高配比达到30%,工业试验时烧结各项指标变化与实验室试验结果基本一致.     

超临界CO2流体萃取莪术挥发油的工艺研究

利用超临界CO2流体萃取技术,以榄香烯为目标物,研究了萃取压力、温度、时间、原料粒度和CO2流量对莪术挥发油萃取率的影响,建立了获得莪术挥发油的最佳工艺条件.实验结果表明,莪术粉粒度40目,萃取压力18 MPa,温度50℃,萃取时间120 min,流量20～30 kg/h条件下,挥发油中榄香烯含量最高,相对含量为2.8%,为以后精馏研究奠定了基础.     

在LabVIEW程序运行中实现控件的动态移动

通过两种在LabVIEW程序运行中实现控件移动的方法的对比,着重介绍了结合了VI Sever技术的动态注册事件结构的用法,从而总结出其具有优化程序、减少内存、提高CPU利用率等方面的优点.     

A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.     

基于μCLinux的NAT设备的设计与开发

NAT(网络地址翻译)技术有效地解决了IP地址紧缺的问题,为实现IPv4到IPv6的平滑过渡发挥了巨大的作用.在一个体积小、重量轻、价格低廉的嵌入式平台上实现NAT设备具有很好的实际意义.文中介绍了NAT技术的原理和实现过程,在自行设计的ARM7嵌入式硬件平台上基于μCLinux操作系统实现了NAT的功能,并通过实现其他相关功能,构建了完整的NAT设备,完成了小型网络接入Internet的方案.     

Effect of boron on the low-cycle fatigue behavior and deformation structure of INCONEL 718 at 650 °C

Symmetrical push-pull low-cycle fatigue (LCF) tests were performed on INCONEL 718 (IN718) containing 12, 29, 60, and 100 ppm B at 650 °C. The results showed that all the alloys experienced a relatively short period of initial cyclic hardening at low strain amplitudes, followed by a regime of saturation or slightly continuous cyclic softening. The initial cyclic hardening phase decreased with increasing strain amplitudes, and disappeared at the high strain amplitudes. A serrated flow was observed in the plastic regions of cyclic stress-strain hysteresis loops. The saturated cyclic stress amplitude at a given strain amplitude was highest for the alloy with 60 ppm B, and lowest for the alloy with 12 ppm B. The LCF lifetime increased with increasing B concentration up to 60 ppm, and then decreased as the B content increased from 60 to 100 ppm. Fractographic analysis suggested that the fracture mode changed from intergranular to transgranular cracking as the B concentration increased. The characteristic deformation microstructures produced by LCF tests at 650 °C, examined via transmission electron microscopy, were regularly spaced arrays of planar deformation bands on {111} slip planes in all four alloys. A ladderlike structure was observed in some local regions in the alloy with 12 ppm B. Heavily deformed planar deformation bands were observed in the fatigued specimens with 100 ppm B. The mechanism of improvement in the LCF life of IN718 due to B addition is discussed.     

我国风机盘管技术现状分析

介绍了近年来我国在风机盘管技术领域的最新成果，在结构形式、强化传热、提高室内空气品质、降低噪音和提高自动控制水平等方面的技术进展情况，分析了目前风机盘管中存在的问题，并对今后的发展方向进行了展望。