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四川省万县市滑坡群灾害灾情评估 总被引:1,自引:0,他引:1
地质灾害的全部过程可以概括为灾前孕育阶段、灾害活动阶段和灾后恢复阶段等三个阶段。对地质灾害灾情评估应包括对灾害灾情进行系统调查、统计、分析和评价等项工作,评估的重点是整个地质灾害形成过程中的灾害活动情况。本文以四川省万县市为例,在论述地质灾害灾情评估理论的基础上,对万县市的地质灾害~滑坡群进行了灾情的评估。 相似文献
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以全血样品为原料,探讨湿法消解-原子荧光法测定全血中的硒含量。血样经硝酸-高氯酸消解后,用硼氢化钠将硒还原成硒化氢,由氩气载入原子化器,产生的原子荧光强度与试液中硒元素含量在一定范围内呈正比,外标法定量。以消解效率为指标,优化样品的消解条件,测定血中硒在0-10μg/L范围内线性情况良好,相关系数为0.9992,最低检出限为0.143μg/L,相对标准偏差为1.51%-1.58%,平均加标回收率为90.86%-104.62%。血中硒的原子荧光测定法灵敏度高,精密度和稳定性好,可应用于血中硒的生物监测。 相似文献
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Xiaomei Fang Ronald Hutcheon Daniel A. Scola 《Journal of polymer science. Part A, Polymer chemistry》2000,38(14):2526-2535
The kinetic mechanism of the microwave cure of a simple phenylethynyl‐terminated imide model compound, 3,4′‐bis[(4‐phenylethynyl)phthalimido]diphenyl ether (PEPA‐3,4′‐ODA) and a phenylethynyl‐terminated imide oligomer (PETI‐5, Mn 5000 g/mol) was studied. Dielectric properties of the model compound and PETI‐5 were measured in the microwave range from 0.4 GHz to 3 GHz. FTIR was used to follow the cure of the model compound (PEPA‐3,4′‐ODA), while thermal analysis (DSC) was used to follow the cure of the PETI‐5 oligomer. The changes in room temperature IR absorbance of phenylethynyl triple bonds at 2214 cm−1 of PEPA‐3,4′‐ODA as a function of cure time were measured after cure temperatures of 300, 310, 320, and 330 °C. The changes in the glass‐transition temperature, Tg, of PETI‐5 as a function of cure time were measured after cure at 350, 360, 370, and 380 °C, respectively. The Tg 's were determined to calculated the relative extent of cure, x, of the PETI‐5 oligomer according to the DiBenedetto equation. For the model compound, the reaction followed first order kinetics, yielding an activation energy of 27.6 kcal/mol as determined by infrared spectroscopy. For PETI‐5, the reaction followed 1.5th order, yielding an activation energy of 17.1 kcal/mol for the whole cure reaction, as determined by Tg using the DiBenedetto method. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2526–2535, 2000 相似文献
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Xiaomei Fang Diana F. Rogers Daniel A. Scola M. P. Stevens 《Journal of polymer science. Part A, Polymer chemistry》1998,36(3):461-470
The kinetic mechanism of the thermal cure of a phenylethynyl-terminated imide model compound, 3,4′-bis[(4-phenylethynyl)phthalimido]diphenyl ether (PEPA-3,4′-ODA) and a phenylethynyl-terminated imide oligomer PETI-5 (MW 5000 g/mol) was studied. FTIR was used to follow the cure of the model compound, while thermal analyses (DSC) was used to follow the cure of the PETI-5 oligomer. The changes in IR absorbance of phenylethynyl triple bonds at 2214 cm−1 of PEPA-3,4′-ODA as a function of cure time were detected at 318, 336, 355, and 373°C, respectively. The changes in the glass transition temperature, Tg, of PETI-5 as a function of time were measured at 350, 360, 370, 380, and 390°C, respectively. The DiBenedetto equation was applied to define the relative extent of cure, x, of the PETI-5 oligomer by Tg. For the model compound, the reaction followed first order kinetics, yielding an activation energy of 40.7 kcal/mol as determined by infrared spectroscopy. For PETI-5, the reaction followed 1.5th order, yielding an activation energy of 33.8 kcal/mol for the whole cure reaction, as determined by Tg using the DiBenedetto method. However, the cure process of PETI-5 just below 90% by this method followed first-order kinetics yielding an activation energy of 37.2 kcal/mol. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 461–470, 1998 相似文献
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Xiaomei Fang Daniel A. Scola 《Journal of polymer science. Part A, Polymer chemistry》1999,37(24):4616-4628
The application of microwave energy to the processing of carbon fiber reinforced phenylethynyl-terminated polyimide composites (PETI-5/IM7) was investigated and evaluated with a variable-frequency microwave furnace. The thermal and physical properties of the composites were measured by dynamic mechanical thermal analysis, thermogravimetric analysis, thermomechanical analysis, and density and composition tests. The mechanical properties were determined by 3-point-bending and short-beam-shear tests at both room temperature and 177 °C. The shear failure surfaces of both microwave- and thermally cured composites were detected with environmental scanning electron microscopy. A comparison of the thermal and microwave processes was conducted to evaluate the advantage of the microwave process. Microwave-cured composites, fabricated under various pressures at the fixed process temperatures, also were investigated. From these studies, it was concluded that microwave energy successfully was used to fabricate PETI-5/IM7 composites with higher glass-transition temperatures (by 11–16 °C) and higher retention in flexural strength, flexural modulus, and shear strength at 177 °C than those fabricated by the thermal process. Furthermore, the microwave processes required only half the time used for the standard thermal process. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4616–4628, 1999 相似文献
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采用随机四参数法对非均质砂质砾岩孔隙结构进行重构, 基于改进的SC-LBM(Shan-Chen格子玻尔兹曼)模型研究润湿流体在多孔介质中的渗吸行为。结果表明: 初始阶段的界面动力学与孔隙骨架的排列有很大关系, 会形成以基质为主的渗吸界面; 流体流经孔喉部分时, 流动断面瞬间缩小, 导致压力梯度和流动阻力迅速增加, 孔吼压力的存在导致流动断面瞬间缩小, 提高了流动阻力, 说明孔隙半径变化对渗吸速率影响较大; 后期阶段, 润湿流体会形成优势渗吸通道, 降低了波及面积, 大幅度降低了渗吸驱油速率。研究结果有助于理解流体在非均质孔隙中的自发渗吸规律, 对发挥裂缝性致密油藏渗吸驱油作用具有重要意义。 相似文献