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41.
Initiation and early propagation of pitting and filiform corrosion on bare alloy AZ91 (9% Al, 1% Zn) are investigated by natural immersion corrosion tests, electrochemical measurements and microanalytical studies. Initiation sites are few. Corrosion spreads from these sites first in the form of filiform corrosion for a limited period of time and pitting which later develops into a cellular type of etching. The important factors affecting filiform corrosion are temperature, material structure and degree of polarization at the anodic sites. Filiform attack on AZ91, unlike the classical mechanisms of filiform corrosion on coated metals, is driven by hydrogen evolution reaction on the cathodic sites of the surface, occurs under significant anodic control, propagates at a high, constant speed independent of degree of polarization along preferential paths determined by compositional and crystallographic factors, and is a temporary phenomenon under open circuit conditions. Pitting corrosion is more predominant with decreasing anodic polarization. 相似文献
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钻石型分形晶格上BEG模型的临界行为 总被引:1,自引:0,他引:1
应用实空间重整化群方法研究了分形结构 -钻石型分级晶格上BEG(Blume Emery Griffith)模型的相变和临界现象 ,得到了重整化变换的递推关系 ,确定了重整化变换的不动点 ,并且计算了临界点附近关联长度的临界指数 发现钻石型分级晶格上BEG模型的相变温度为无穷大 ,这表明系统永远处于有序态 相似文献
44.
Forecasting based on sectoral energy consumption of GHGs in Turkey and mitigation policies 总被引:1,自引:0,他引:1
Recently, global warming and its effects have become one of the most important themes in the world. Under the Kyoto Protocol, the EU has agreed to an 8% reduction in its greenhouse gas (GHG) emissions by 2008–2012. The GHG emissions (total GHG, CO2, CO, SO2, NO2, E (emissions of non-methane volatile organic compounds)) covered by the Protocol are weighted by their global warming potentials (GWPs) and aggregated to give total emissions in CO2 equivalents. The main subject in this study is to obtain equations by the artificial neural network (ANN) approach to predict the GHGs of Turkey using sectoral energy consumption. The equations obtained are used to determine the future level of the GHG and to take measures to control the share of sectors in total emission. According to ANN results, the maximum mean absolute percentage error (MAPE) was found as 0.147151, 0.066716, 0.181901, 0.105146, 0.124684, and 0.158157 for GHG, SO2, NO2, CO, E, and CO2, respectively, for the training data with Levenberg–Marquardt (LM) algorithm by 8 neurons. R2 values are obtained very close to 1. Also, this study proposes mitigation policies for GHGs. 相似文献
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N Alptekin S Se?kin S Do?ru-Abbaso?lu F Yelkenci N Ko?ak-Toker G Toker M Uysal 《Canadian Metallurgical Quarterly》1996,34(3-4):167-169
The effects of water-immersion restraint (WIR) stress on lipid peroxide, glutathione (GSH), glutathione peroxidase (GSH-Px), gamma-glutamylcysteine synthetase (gamma-GCS) and gamma-glutamyltranspeptidase (gamma-GT) activities in several tissues of rats were investigated. Hepatic and intestinal lipid peroxide levels were increased significantly in the WIR stress group. In both tissues, GSH levels were significantly decreased and gamma-GCS activity was significantly increased. In addition, gamma-GT activities remained unchanged in both tissues following WIR stress. However, lipid peroxide and GSH levels did not change in the stomach and brain in the WIR stress group compared to the control group. These results suggest that lipid peroxidation, but not the depression of GSH synthesis and/or the increase of GSH breakdown may be a factor in hepatic and intestinal GSH reduction following WIR stress. 相似文献
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基于多用户多输入多输出(MIMO)有限反馈系统提出了一种收发联合波束成形方法。该方法在发送端采用每个用户酉速率控制(PU2RC)波束成形技术,在接收端采用基于信干噪比(SINR)最大化的天线合并算法。天线合并算法利用用户SINR的广义Rayleigh熵特性寻找最佳的天线合并矢量。仿真结果表明,该方法能充分利用信道信息,不仅改善了传统PU2RC系统的和速率性能,相对于已有的迫零(ZF)联合波束成形方法,对信道状态信息的量化误差的敏感性更低,用户选择算法的复杂度更低,且低速率反馈条件下和速率性能更优。 相似文献
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Conventional constant false alarm rate (CFAR) methods use a fixed number of cells to estimate the background variance. For homogeneous environments, it is desirable to increase the number of cells, at the cost of increased computation and memory requirements, in order to improve the estimation performance. For nonhomogeneous environments, it is desirable to use less number of cells in order to reduce the number of false alarms around the clutter edges. In this work, we present a solution with two exponential smoothers (first order IIR filters) having different time-constants to leverage the conflicting requirements of homogeneous and nonhomogeneous environments. The system is designed to use the filter having the large time-constant in homogeneous environments and to promptly switch to the filter having the small time constant once a clutter edge is encountered. The main advantages of proposed Switching IIR CFAR method are computational simplicity, small memory requirement (in comparison to windowing based methods) and its good performance in homogeneous environments (due to the large time-constant smoother) and rapid adaptation to clutter edges (due to the small time-constant smoother). 相似文献