A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the...A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.展开更多
从宏观和微观角度 ,系统地研究了粉末冶金法 Si Cp/ Al复合材料制备工艺对 Si Cp 分布均匀性的影响。研究结果表明 :混粉过程中 ,粉末混合物宏观均匀很容易达到 ,但微观均匀较差。干混存在最佳混合时间。挤压过程可大大提高 Si Cp 分布...从宏观和微观角度 ,系统地研究了粉末冶金法 Si Cp/ Al复合材料制备工艺对 Si Cp 分布均匀性的影响。研究结果表明 :混粉过程中 ,粉末混合物宏观均匀很容易达到 ,但微观均匀较差。干混存在最佳混合时间。挤压过程可大大提高 Si Cp 分布微观均匀性。展开更多
A modified mixed strengthening model was proposed for describing the yield strength of particle reinforced aluminum matrix composites.The strengthening mechanisms of the composites were analyzed based on the microstru...A modified mixed strengthening model was proposed for describing the yield strength of particle reinforced aluminum matrix composites.The strengthening mechanisms of the composites were analyzed based on the microstructures and compression mechanical properties.The distribution uniformity of reinforcements and cooperation relationship among dislocation mechanisms were considered in the modified mixed strengthening model by introducing a distribution uniformity factor u and a cooperation coefficient fc,respectively.The results show that the modified mixed strengthening model can accurately describe the yield strengths of Al3Ti/2024Al composites with a relative deviation less than1.2%,which is much more accurate than other strengthening models.The modified mixed model can also be used to predict the yield strength of Al3Ti/2024Al composites with different fractions of reinforcements.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09A209)
文摘A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.
基金Projects (51875121,51405100) supported by the National Natural Science Foundation of ChinaProjects (2014M551233,2017T100237) supported by the China Postdoctoral Science Foundation+2 种基金Project (ZR2017PA003) supported by the Natural Science Foundation of Shandong Province,ChinaProject (2017GGX202006) supported by the Plan of Key Research and Development of Shandong Province,ChinaProject (2016DXGJMS05) supported by the Plan of Science and Technology Development of Weihai,China
文摘A modified mixed strengthening model was proposed for describing the yield strength of particle reinforced aluminum matrix composites.The strengthening mechanisms of the composites were analyzed based on the microstructures and compression mechanical properties.The distribution uniformity of reinforcements and cooperation relationship among dislocation mechanisms were considered in the modified mixed strengthening model by introducing a distribution uniformity factor u and a cooperation coefficient fc,respectively.The results show that the modified mixed strengthening model can accurately describe the yield strengths of Al3Ti/2024Al composites with a relative deviation less than1.2%,which is much more accurate than other strengthening models.The modified mixed model can also be used to predict the yield strength of Al3Ti/2024Al composites with different fractions of reinforcements.
