反射式可调移相器

针对现代通信中线性功率放大器的补偿要求,介绍一种利用反射理论设计可调移相器,实现大范围移相,同时幅度波动很小,并详细讨论了它的工作原理和实验结果。     

黑岱沟露天煤矿半连续工艺移设步距的确定

露天矿山开采的过程中,常常面临设备及道路移设的问题。频繁的移设会影响露天矿生产进度,降低生产效率,而不移设则会由于运距增加,影响内排等生产计划而降低矿山经济效益,因此确定合理的移设步距,对矿山生产实际而言意义非凡。针对所述问题,以黑岱沟露天煤矿为研究对象,根据黑岱沟露天矿生产实际和采矿学理论基础,详尽分析与采场中间运煤通道移设距离影响因素,使用数学建模的方法,建立运煤通道移设步距数学模型;并根据成组破碎站移设的特点,建立移设补偿效果移设步距模型,进一步分析移设时机。得到的移设优化模型,揭示了移设步距对矿山经济效益的影响。该项研究对露天煤矿山移设工作有一定的指导意义,可以增加矿山经济效益。     

A simulation study on the enhancement of the shift reaction by water injection into a gasifier

Although coal gasification is a clean and efficient use of coal, a reduction of CO₂ emissions is needed to mitigate global warming. The aim of this study was to improve the thermal efficiency of fuel production and electricity generation by dry coal feed gasification. The primary cause of thermal efficiency loss is steam use in a water-gas shift reactor. The shift reactor, installed downstream from the gasifier, uses a catalyst to adjust the H₂/CO ratio of the syngas. We have proposed a new process in which water is injected at the outlet of the gasifier and is vaporized to enhance the extent of the shift reaction. This process utilizes the high temperature of the syngas, which is sufficient for the shift reaction to occur without a catalyst. We have developed a model that incorporates the shift reaction velocity to evaluate our proposed process. In an optimized 5-stage water supply case, we found that the CO conversion reaches 9.9% at a water/syngas ratio of 0.14 mol/mol (water/CO = 0.25 mol/mol); the CO conversion needed for dimethyl ether production is 31%. This new process can improve the efficiency and reduce the cost of coal gasification.     

Studies of poisson''s ratio variation for solid propellant grains under ignition pressure loading

For structural integrity evaluation of solid propellant grains, an accurate estimation of the stress and strain response is essential, because of the viscoelastic nature of the polymer material. The results of an investigation on solid propellant grains considering the effect of Poisson's ratio υ variation under ignition pressurization are presented. Traditionally the υ value of solid propellant grains is assumed to be a constant (e.g. 0.4999) to simplify the experimental task, but the real υ value is from 0.47 to 0.4999 depending on the chemical design of the solid propellant grains. In order to simulate the time–temperature-dependent behaviour of viscoelastic polymer materials for a range of Poisson's ratio values, the concepts of a time–temperature shift principle and reduced integration were used. In addition, eight different Poisson's ratio values from 0.47 to 0.4999 were assumed and compared using the finite element method. Results show that the Poisson's ratio variation effect is very important for structural integrity of solid propellant grains, and the stress and strain responses versus Poisson's ratio variation are nonlinear because the type of polymer material is changed from incompressible to compressible. Under ignition pressure loading, the stress and strain responses in the compressible case (υ≠0.5) are much higher than those of the incompressible case (υ0.5). Therefore unlike metallic structures, an exact value of Poisson's ratio for polymer materials is very important, and an improper assumption (υ0.5) may cause the structural integrity of a missile system subjected to pressure loading to be wrongly evaluated.     

祖冲之算法分析及其硬件实现

详细分析了3GPP LTE国际加密标准祖冲之(ZUC)算法的结构及其硬件实现过程.ZUC流式加密算法采用了线性反馈移位寄存器(LFSR),比特重组(BR)和非线性函数F的三层结构设计,具有很高的安全性.同时,ZUC算法在设计时就充分考虑了软硬件实现的低复杂度,因此非常适合于硬件实现.ZUC算法在Altera的Cyclone FPGA上实现,需要2 013个逻辑单元,不需要存储器.在中芯国际SMIC 0.18 μm的CMOS工艺上实现的芯片面积为109 823 μm2.     

摩托车速控无级变速器设计

根据踏板式摩托车无级变速器使用过程中存在的问题,通过改变控制变速比的方法,使之适应摩托车的各种工况。     

钢轨踏面裂纹的表面波B扫描成像检测

用超声表面波来检测钢轨踏面裂纹,设计和加工了具有不同深度的裂纹试样。采用频率为0．5MHz的表面波探头对裂纹试样进行B扫描成像检测。为克服钢轨中传播的多模式表面波导致检测图像分辨率低的缺点,采用对A扫描信号移位叠加的方法对图像进行了处理。此方法不仅能对表面裂纹进行较精确的定位,也能定性区分表面裂纹的深度。     

THEORETICAL ANALYSIS OF HIGH AND LOW TEMPERATURE SHIFT CONVERTERS

Theoretical analysis is performed to study catalytic reaction of CO in bolh high and low temperature shift converters. The study includes comparison between model predictions and data collected from local industries in Kuwait. Theoretical models are developed to simulate temperature and conversion profiles of CO in both the high and low shift converters. Good fits are obtained between the theoretical predictions of exit CO conversion and axial temperature profiles and the collected data. Calculations show existence of an optimum feed temperature for the high temperature shift converter. Such an optimum does not exist for the low temperature shift system because of physical limitations on operating conditions. @KEYWORDS: Carbon monoxide, Shift converters.     

改善动力换挡变速箱换挡品质的研究

本文对动力换挡变速箱的换挡品质评价指标进行了研究。通过对换挡品质影响因素的分析,提出了改善换挡品质的控制方法,并在液力传动系统试验台上进行了换挡品质试验研究,对改善换挡品质的方法进行了进一步的分析。     

对气测全量曲线“负漂”的认识及资料应用价值的探讨

对于TDC—综合录井仪的气测全量曲线“负漂”成因机理,通过理论分析和现场试验,有了初步认识。全量曲线“负漂”峰是惠斯顿电桥鉴定器测量低导热系数气体的正常反应,它对判断CO_2气体和N_2气体的存在有较好的应用价值。它可为今后进一步研究地层中高矿化度水层、油水同层和气水同层的解释方法提供一项特殊价值的气测分析资料。