Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the orig...Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.展开更多
This paper investigates the influence of the deviation in freeze pipe installation on the development of the frozen wall in long cross passages by numerical simulation with ANSYS software.The study case is from the ar...This paper investigates the influence of the deviation in freeze pipe installation on the development of the frozen wall in long cross passages by numerical simulation with ANSYS software.The study case is from the artificial ground freezing project along the Fuzhou Metro Line 2 between Ziyang Station and Wuliting Station.Two freezepipe configurations,i.e.,one with perfectly aligned pipes without any deviation from design and another with randomly distributed deviation,are included for comparison.The effect of the random deviation in the freeze pipes on frozen wall interconnection time,the thickness of the frozen wall and the development of the temperature field is explored.For the characteristic section of the numerical model at a depth of 25 m,it is found that the frozen wall interconnection time under the random deviation case and no deviation case is 24 days and 18 days,respectively.The difference in the thickness of the thinnest frozen wall segment between the random deviation and no deviation cases is the largest in the early freezing stage(up to 0.75 m),which decreases with time to 0.31 m in the late freezing stage.The effects of random deviation are more significant in the early freezing stage and diminish as the freezing time increases.展开更多
A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy（CIAE）,Lanzhou University（LU）,Peking University（PU）and Sichuan University（SU）from 1989 to 1994 for ge...A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy（CIAE）,Lanzhou University（LU）,Peking University（PU）and Sichuan University（SU）from 1989 to 1994 for generation of long-lived radionuclides of im-portance in fusion reactor technology.The cross sections are measured for the reactions <sup>109</sup>Ag（n,2n）<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu（n,2n）<sup>150</sup>Eu<sup>m</sup>,<sup>153</sup>Eu（n,2n）<sup>152</sup>Eu<sup>8</sup>,<sup>159</sup>Tb（n,2n）<sup>158</sup>Tb,<sup>179</sup>Hf（n,2n ）<sup>178</sup>Hf<sup>m2</sup>,<sup>182</sup>W（n,n′α）<sup>178</sup>Hf<sup>m2</sup>,<sup>187</sup>Re（n,2n）<sup>186</sup>Re<sup>m</sup> and <sup>193</sup>Ir（n,2n）<sup>192</sup>Ir<sup>m2</sup>at 14 MeV,<sup>109</sup>Ag（n,2n）<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu（n,2n）<sup>150</sup>Eu<sup>m</sup>,<sup>159</sup>Tb（n,2n）<sup>158</sup>Tb and <sup>179</sup>Hf（n,2n）<sup>178</sup>Hf<sup>m2</sup>at 9.5 and 9.9 MeV,and<sup>98</sup>Mo（n,γ）<sup>199</sup>Mo（β<sup>-</sup>）→<sup>99</sup>Tc,<sup>165</sup>Ho（n.γ）<sup>166</sup>Ho<sup>m</sup> and <sup>151</sup>Eu（n,γ）<sup>152</sup>Eu<sup>8</sup> in the energy range of20～1100 keV.Some of them were calculated by systematic and HFTT code,which was basedon the compound nucleus evaporation and the preequilibrium exciton model.展开更多
目前情感分析任务经常只聚焦于评论文本本身,忽略了评论者与被评论者的个体偏差特征,会显著影响对文本的整体情感判断。针对上述问题,提出一种融合评论双边个体偏差信息的文本情感分析模型UP-ATL(User and Product-Attention TranLSTM)...目前情感分析任务经常只聚焦于评论文本本身,忽略了评论者与被评论者的个体偏差特征,会显著影响对文本的整体情感判断。针对上述问题,提出一种融合评论双边个体偏差信息的文本情感分析模型UP-ATL(User and Product-Attention TranLSTM)。该模型使用自注意力机制、交叉注意力机制对评论文本与个体偏差信息分别进行双向融合,在融合过程中采用定制化权重的计算方式,以缓解实际应用场景中冷启动带来的数据稀疏问题,最终得到特征充分融合的评论文本和评论双边的表示信息。选取餐饮领域、电影领域的三个真实公开数据集Yelp2013、Yelp2014、IMDB进行效果验证,与UPNN(User Product Neural Network)、NSC(Neural Sentiment Classification)、CMA(Cascading Multiway Attention)、HUAPA(Hierarchical User And Product multi-head Attention)等基准模型进行比较。实验结果表明,相较于比较模型中最好的HUAPA模型,UP-ATL的准确度在三个数据集上依次分别提高了6.9、5.9和1.6个百分点。展开更多
基金The financial supports of the National Natural Science Foundation of China (grant nos. 21373042, 21677029 and 51402036)the Fundamental Research Funds for the Central Universities (grant no. DUT15YQ109)
文摘Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.
基金This research was supported by the project of Natural Science Foundation of Fujian Province(No.2022J01925)supported by the project of the Fuzhou Science and Technology Plan Project(2021-P-047)supported by the Open Project Program Foundation of Engineering Research Center of underground mine construction,Ministry of Education(Anhui University of Science and Technology)(No.JYBGCZX2021104).
文摘This paper investigates the influence of the deviation in freeze pipe installation on the development of the frozen wall in long cross passages by numerical simulation with ANSYS software.The study case is from the artificial ground freezing project along the Fuzhou Metro Line 2 between Ziyang Station and Wuliting Station.Two freezepipe configurations,i.e.,one with perfectly aligned pipes without any deviation from design and another with randomly distributed deviation,are included for comparison.The effect of the random deviation in the freeze pipes on frozen wall interconnection time,the thickness of the frozen wall and the development of the temperature field is explored.For the characteristic section of the numerical model at a depth of 25 m,it is found that the frozen wall interconnection time under the random deviation case and no deviation case is 24 days and 18 days,respectively.The difference in the thickness of the thinnest frozen wall segment between the random deviation and no deviation cases is the largest in the early freezing stage(up to 0.75 m),which decreases with time to 0.31 m in the late freezing stage.The effects of random deviation are more significant in the early freezing stage and diminish as the freezing time increases.
基金The project cartied OHt under IAEA Research Agreement No 5060/CF
文摘A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy（CIAE）,Lanzhou University（LU）,Peking University（PU）and Sichuan University（SU）from 1989 to 1994 for generation of long-lived radionuclides of im-portance in fusion reactor technology.The cross sections are measured for the reactions <sup>109</sup>Ag（n,2n）<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu（n,2n）<sup>150</sup>Eu<sup>m</sup>,<sup>153</sup>Eu（n,2n）<sup>152</sup>Eu<sup>8</sup>,<sup>159</sup>Tb（n,2n）<sup>158</sup>Tb,<sup>179</sup>Hf（n,2n ）<sup>178</sup>Hf<sup>m2</sup>,<sup>182</sup>W（n,n′α）<sup>178</sup>Hf<sup>m2</sup>,<sup>187</sup>Re（n,2n）<sup>186</sup>Re<sup>m</sup> and <sup>193</sup>Ir（n,2n）<sup>192</sup>Ir<sup>m2</sup>at 14 MeV,<sup>109</sup>Ag（n,2n）<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu（n,2n）<sup>150</sup>Eu<sup>m</sup>,<sup>159</sup>Tb（n,2n）<sup>158</sup>Tb and <sup>179</sup>Hf（n,2n）<sup>178</sup>Hf<sup>m2</sup>at 9.5 and 9.9 MeV,and<sup>98</sup>Mo（n,γ）<sup>199</sup>Mo（β<sup>-</sup>）→<sup>99</sup>Tc,<sup>165</sup>Ho（n.γ）<sup>166</sup>Ho<sup>m</sup> and <sup>151</sup>Eu（n,γ）<sup>152</sup>Eu<sup>8</sup> in the energy range of20～1100 keV.Some of them were calculated by systematic and HFTT code,which was basedon the compound nucleus evaporation and the preequilibrium exciton model.
