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LI ZhiLin HUANG Qin WU YuanQi & LI ZhiFeng College of Materials Science Engineering Beijing University of Chemical Technology Beijing China 《中国科学E辑(英文版)》2007,50(4):462-471
Because of its excellent properties, zirconia ceramics has already been widely applied. Its phase transformation affects its properties. The research on the mechanism of its phase transformation is very important to control the phase transformation as well as its properties. The valence electron structure of cubic zirconia, tetragonal zirconia and monoclinic zirconia are calculated with the em-pirical electron theory in solids and molecules in this paper. The results show that the total numbers of the covalent electron pairs which form their strong bond framework are 3.19184, 3.45528 and 3.79625, respectively. According to the view-point of the C-Me segregating theory in solid alloys, it can be deduced that the phase transformation order of zirconia should be liquid phase→cubic phase→tetragonal phase→monoclinic phase. The deduction from valence electron struc-ture is completely in accordance with the experimental results, so the electron theory of phase transformation in alloys can be expanded to ceramics materials. 相似文献
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分组密码一直是解决信息系统安全问题的常用技术方法。尽管作为分组密码典型代表的DES算法目前已被更为安全的Rijndael算法取代,但其中所体现的设计思想和设计原则依然值得研究和借鉴。文中以DES加密算法为例,在分析DES加密过程、密钥计算、加密函数和解密过程的基础上,探讨分组密码的设计原则。指出组件结构标准化原则、算法和密钥分离原则、扩散和混淆原则以及均匀性和随机性原则是现代分组密码设计的基本原则。这些原则是现代分组密码设计的出发点。 相似文献
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文章介绍了日立Z-5000型原子吸收分光光度计火焰系统和石墨炉系统在日常分析中出现的故障现象和解决方法。 相似文献
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在改变催化层中聚四氟乙烯(PTFE)、造孔剂含量和热压压力等条件下制备气体扩散电极,通过计时电位法、阴极极化曲线对气体扩散电极进行测定,并将其结果用最小二乘法拟合得出电极的制备条件与氧气还原反应电化学参数之间的关系。电化学测试结果表明,各种条件下制备的电极的阴极极化过程都符合Rho提出的半经验公式规律;当气体扩散电极催化层PTFE面密度3.33 mg/cm2、造孔剂(NH4)HCO3面密度1.05 mg/cm2以及热压压力3.69 MPa时,气体扩散电极的氧还原活性最佳。 相似文献
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By introducing the distribution probability of structural units in austenite containing alloying elements and considering
its effects on phase transformation, this paper establishes a calculation model of distribution probability of structural
units. A new valence electron structure (VES) parameter-transformation effect coefficient of alloying elements (HL), is defined and then studied both theoretically and experimentally. The relationship between the parameter HL and the multiplying factor (the quenching capability factor) of alloying elements is studied. The results indicate that the
two parameters (HL and the quenching capability factor) have the same variation characteristic and substance feature. Therefore, the multiplying
factor virtually expresses the relative quantity of structural units in the alloying elements-containing austenite.
Supported by the National Natural Science Foundation of China (Grant Nos. 50271009, 503334010) 相似文献
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道路、桥梁的空间信息和属性信息,经过外业的采集、调查、成图(AutoCAD)之后,便是这些海量数据的编辑入库工作,本文讲述了嘉兴市主城区范围内的道路、桥梁信息采集的内容,以及相关数据的后期编辑和入库工作。 相似文献
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Based on the empirical electron theory of solids and molecules (EET), the statistical values of valence electron structure
parameters Sn
A and SE
A which can characterize the properties of alloy phases are calculated, and influences of alloying elements (e.g., V, Nb, Mo,
Hf, Zr, Fe, Mn, Co, Cr, Si, and so on) on the phase transition temperature and eutectoid reaction of titanium alloy are discussed
with the statistical values of valence electron structure parameters. The research results agree well with real situations.
Supported by the National Natural Science Foundation of China (Grant No. 50471022, 50741004) and National Key Basic Research
Program of China (“973”) (Grant No. 2007CB613807) 相似文献
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