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煤热解动力学分布活化能模型适用性分析 被引量:11
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作者 赵岩 邱朋华 +4 位作者 谢兴 陈希叶 林丹 孙绍增 刘栗 《煤炭转化》 CAS CSCD 北大核心 2017年第1期13-18,共6页
以三种不同升温速率下准东原煤样品的热解失重数据为研究对象,应用分布活化能模型(DAEM)法进行动力学计算,分析了此种方法在煤热解整体动力学研究中的适用性.结果表明,由于升温速率对热解过程的影响以及反应机理的转变,DAEM法对煤热解... 以三种不同升温速率下准东原煤样品的热解失重数据为研究对象,应用分布活化能模型(DAEM)法进行动力学计算,分析了此种方法在煤热解整体动力学研究中的适用性.结果表明,由于升温速率对热解过程的影响以及反应机理的转变,DAEM法对煤热解二次脱气阶段失重数据的适用性较差;失水脱气及二次脱气阶段失重的取舍对各转化率所对应的活化能值具有不同的影响,而对活化能分布函数则影响不大;在几乎整个热解过程中,频率因子和活化能之间均呈现明显的动力学补偿效应,且其具体表现形式仅取决于煤种,而与所选取的温度计算范围关系不大. 展开更多
关键词 准东煤 热解 动力学 分布活化能模型 活化能分布函数
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基于简单碰撞理论煤粉燃烧动力学模型的研究——PART Ⅰ:理论建模与热重实验 被引量:5
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作者 傅培舫 方庆艳 +1 位作者 姚斌 周怀春 《工程热物理学报》 EI CAS CSCD 北大核心 2005年第2期331-334,共4页
本文根据反应动力学的简单碰撞理论(SCT),建立了气固两相反应通用模型,进一步研究了煤焦燃烧和燃尽的统一动力学模型;粉煤悬浮燃烧时挥发分的析出模型也可包含在该模型中;该模型充分考虑了粉煤在热天平中与在炉内燃烧条件下氧气浓度和... 本文根据反应动力学的简单碰撞理论(SCT),建立了气固两相反应通用模型,进一步研究了煤焦燃烧和燃尽的统一动力学模型;粉煤悬浮燃烧时挥发分的析出模型也可包含在该模型中;该模型充分考虑了粉煤在热天平中与在炉内燃烧条件下氧气浓度和氧气可达比表面积变化规律的差异,并给出了计算活化能函数和氧气可达比表面积的新方法,可提高利用热天平获取的动力学参数对炉内煤粉燃烧速率预报的准确性。通过热重分析和已经报道的试验数据对模型的合理性进行了检验。 展开更多
关键词 煤粉燃烧 SCT动力学模型 活化能函数 氧气可达比表面积 TGA
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Determination of kinetic parameters from calorimetric study of solid state reactions in 7150 Al-Zn-Mg alloy 被引量:13
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作者 K. S. GHOSH N. GAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第6期1199-1209,共11页
Differential scanning calorimetric (DSC) study was carried out at different heating rates to examine the solid state reactions in a 7150 A1-Zn-Mg alloy in water-quenched (WQ) state, naturally and artificially aged... Differential scanning calorimetric (DSC) study was carried out at different heating rates to examine the solid state reactions in a 7150 A1-Zn-Mg alloy in water-quenched (WQ) state, naturally and artificially aged tempers. The exothermic and endothermic peaks of the thermograms indicating the solid state reaction sequence were identified. The shift of peak temperatures to higher temperatures with increasing heating rates suggests that the solid state reactions are thermally activated and kinetically controlled. The artificial aging behaviour of the alloy was assessed by measuring the variations of hardness with aging time. The fraction of transformation (Y), the rate of transformation (dY/dt), the transformation functionflY), and the kinetic parameters such as activation energy (Q) and frequency factor (k0) of all the solid state reactions in the alloy were determined by analyzing the DSC data, i.e. heat flow involved with the corresponding DSC peaks. It was found that the kinetic parameters of the solid state reactions are in good agreement with the published data. 展开更多
关键词 7150 Al-Zn-Mg alloy DSC aging behaviour activation energy transformation function
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Thermodynamic approach to synthesis of silver nanocrystalline by mechanical milling silver oxide 被引量:1
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作者 Gholam Reza KHAYATI Kamal JANGHORBAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第2期543-547,共5页
Thermodynamic analysis of the possibility of silver nanocrystalline preparation by high energy milling silver oxide was investigated. The molar Gibbs free energy function of mechanically activated samples was calculat... Thermodynamic analysis of the possibility of silver nanocrystalline preparation by high energy milling silver oxide was investigated. The molar Gibbs free energy function of mechanically activated samples was calculated from the structural defects such as amorphization, dislocation and surface energy. According to the molar Gibbs free energy function, the equilibrium temperature of mechanical reduction of silver oxide milled for 21 h was estimated at about 304 K. Consequently, at this temperature silver oxide cannot be stable and will transform to silver during the milling. 展开更多
关键词 silver nanocrystalline silver oxide Gibbs free energy function mechanical activation
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Convergence of On-Line Gradient Methods for Two-Layer Feedforward Neural Networks
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作者 李正学 吴微 张宏伟 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2001年第2期12-12,共1页
A discussion is given on the convergence of the on-line gradient methods for two-layer feedforward neural networks in general cases. The theories are applied to some usual activation functions and energy functions.
关键词 on-line gradient method feedforward neural network convergence.
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