Based on energy theory and tests of rocks with initial confining pressures of 10, 20 and 30 MPa under different unloading paths, the processes of strain energy conversion were investigated. The absorbing strain energy...Based on energy theory and tests of rocks with initial confining pressures of 10, 20 and 30 MPa under different unloading paths, the processes of strain energy conversion were investigated. The absorbing strain energy for axial compression, the dissipating strain energy for plastic deformation and cracks propagation, the expending strain energy for circumferential deformation, and the storing and releasing elastic strain energy were considered. Unloading paths included the condition of fixing axial pressure and unloading axial pressure, increasing axial pressure and unloading confining pressure, as well as unloading axial pressure and confining pressure simultaneously. Results show that expending strain energy for circumferential deformation has mainly evolved from absorbing strain energy for axial compression in three unloading paths during unloading processes. Dissipating strain energy is significantly increased only near the peak point. The effect of initial confining pressure on strain energy is significantly higher than that of unloading path. The strain energy is linearly increased with increasing initial confining pressure. The unloading path and initial confining pressure also have great influence on the energy dissipation. The conversion rate of strain energy in three paths is increased with increasing initial confining pressure, and the effect of initial confining pressure on conversion rate of strain energy is related with the unloading paths.展开更多
The highly efficient photovoltaic cells require the In-rich InGaN film with a thickness more than 300 nm to achieve the effective photo-electricity energy conversion.However,the InGaN thick films suffer from poor crys...The highly efficient photovoltaic cells require the In-rich InGaN film with a thickness more than 300 nm to achieve the effective photo-electricity energy conversion.However,the InGaN thick films suffer from poor crystalline quality and phase separations by using the conventional low-pressure metal organic chemical vapor deposition(MOCVD).We report on the growth of 0.3-1μm-thick InGaN films with a specially designed vertical-type high-pressure MOCVD at the pressure up to 2.5 atms.The In incorporation is found to be greatly enhanced at the elevated pressures although the growth temperatures are the same.The phase separations are inhibited when the growth pressure is higher than atmospheric pressure,leading to the improved crystalline quality and better surface morphologies especially for the In-rich InGaN.The In 0.4 Ga 0.6 N with the thickness of 300 nm is further demonstrated as the active region of solar cells,and the widest photoresponse range from ultraviolet to more than 750 nm is achieved.展开更多
利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的全球再分析数据,使用局地多尺度能量涡度分析法(localized Multiscale Energy and Vorticity Analysis,MS-EVA)分析了初夏影响江淮流域极端...利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的全球再分析数据,使用局地多尺度能量涡度分析法(localized Multiscale Energy and Vorticity Analysis,MS-EVA)分析了初夏影响江淮流域极端干旱发生的欧洲关键区动能变率的时间特征及其动能收支。结果表明:初夏欧洲关键区高层动能有增长趋势时,我国江淮流域极易发生极端干旱事件。该处增长的动能主要来自天气尺度动能的传输,其次来自气压梯度力做功和动能的垂直输送;动能向有效位能的转换和季节平均尺度动能的传输是高层动能流失的原因。深入研究三项动能来源因子后发现:上层增加的动能一部分来自低层北大西洋东岸和欧洲大陆西南地区的动能东传,在欧洲辐合后向上输送,为高层传递能量;同时,由于关键区地面热强迫增强,使垂直风切变增大,大气斜压稳定度降低,气压梯度力做功项增大,使得高层动能得到补充。在此期间,由于地面加热,天气尺度传输项对高层动能的传输量也增多。关键区增加的净能量经西风环流在江淮地区辐合,有助于该地上空的脊增强,促进了极端干旱事件发生。该结果从能量转换角度探究了江淮流域干旱发生的部分成因,为干旱预估提供依据。展开更多
基金Project(51324744)supported by the National Natural Science Foundation of ChinaProject(71380100006)supported by the Innovation Foundation of Doctoral Student in Hunan Province,China
文摘Based on energy theory and tests of rocks with initial confining pressures of 10, 20 and 30 MPa under different unloading paths, the processes of strain energy conversion were investigated. The absorbing strain energy for axial compression, the dissipating strain energy for plastic deformation and cracks propagation, the expending strain energy for circumferential deformation, and the storing and releasing elastic strain energy were considered. Unloading paths included the condition of fixing axial pressure and unloading axial pressure, increasing axial pressure and unloading confining pressure, as well as unloading axial pressure and confining pressure simultaneously. Results show that expending strain energy for circumferential deformation has mainly evolved from absorbing strain energy for axial compression in three unloading paths during unloading processes. Dissipating strain energy is significantly increased only near the peak point. The effect of initial confining pressure on strain energy is significantly higher than that of unloading path. The strain energy is linearly increased with increasing initial confining pressure. The unloading path and initial confining pressure also have great influence on the energy dissipation. The conversion rate of strain energy in three paths is increased with increasing initial confining pressure, and the effect of initial confining pressure on conversion rate of strain energy is related with the unloading paths.
基金supported by the JST-PRESTO(JPMJPR19I7)World Premier International Research Center(WPI)initiative on Materials Nanoarchitectonics(MANA),Ministry of Education,Culture,Sports,Science&Technology(MEXT)in JapanNational Key Research and Development Program of China(2018YFE0125700).
文摘The highly efficient photovoltaic cells require the In-rich InGaN film with a thickness more than 300 nm to achieve the effective photo-electricity energy conversion.However,the InGaN thick films suffer from poor crystalline quality and phase separations by using the conventional low-pressure metal organic chemical vapor deposition(MOCVD).We report on the growth of 0.3-1μm-thick InGaN films with a specially designed vertical-type high-pressure MOCVD at the pressure up to 2.5 atms.The In incorporation is found to be greatly enhanced at the elevated pressures although the growth temperatures are the same.The phase separations are inhibited when the growth pressure is higher than atmospheric pressure,leading to the improved crystalline quality and better surface morphologies especially for the In-rich InGaN.The In 0.4 Ga 0.6 N with the thickness of 300 nm is further demonstrated as the active region of solar cells,and the widest photoresponse range from ultraviolet to more than 750 nm is achieved.
文摘利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的全球再分析数据,使用局地多尺度能量涡度分析法(localized Multiscale Energy and Vorticity Analysis,MS-EVA)分析了初夏影响江淮流域极端干旱发生的欧洲关键区动能变率的时间特征及其动能收支。结果表明:初夏欧洲关键区高层动能有增长趋势时,我国江淮流域极易发生极端干旱事件。该处增长的动能主要来自天气尺度动能的传输,其次来自气压梯度力做功和动能的垂直输送;动能向有效位能的转换和季节平均尺度动能的传输是高层动能流失的原因。深入研究三项动能来源因子后发现:上层增加的动能一部分来自低层北大西洋东岸和欧洲大陆西南地区的动能东传,在欧洲辐合后向上输送,为高层传递能量;同时,由于关键区地面热强迫增强,使垂直风切变增大,大气斜压稳定度降低,气压梯度力做功项增大,使得高层动能得到补充。在此期间,由于地面加热,天气尺度传输项对高层动能的传输量也增多。关键区增加的净能量经西风环流在江淮地区辐合,有助于该地上空的脊增强,促进了极端干旱事件发生。该结果从能量转换角度探究了江淮流域干旱发生的部分成因,为干旱预估提供依据。