The assumption of the local equilibrium of hydrogen distribution in metals[1]was used in the model formerly developed[2]to describe the diffu- sion of hydrogen in metals.From the assumption a direct relationship betwe...The assumption of the local equilibrium of hydrogen distribution in metals[1]was used in the model formerly developed[2]to describe the diffu- sion of hydrogen in metals.From the assumption a direct relationship between the hydrogen diffusivity and the hydrogen concentration in metals is estab- lished as D=D_o/{1+N_x(k/p)/[1+C(k/p)]} The comparison between the two results drawn from the assumption of equilibrium and the dynam- ics of hydrogen trapping[3]was also presented.The computation results well explained the scattering phenomenon existed in hydrogen diffusion data and suggested that the experimental conditions should be identical for the study of hydrogen permeation in metals.展开更多
This article questions the recent scholarship that attempts to draw parallels between Qing China before 1800 and the so-called fiscal-military states in early modem Europe. Beginning with a survey of＂fiscal cycles＂ ...This article questions the recent scholarship that attempts to draw parallels between Qing China before 1800 and the so-called fiscal-military states in early modem Europe. Beginning with a survey of＂fiscal cycles＂ in China from the 1640s to the 1850s, the author argues that border wars and territorial expansion had little impact on the Qing state＇s tax system and bureaucracy. Contrary to the high level of taxation necessitated by escalation in military spending among the contemporary European states, the Qing pursued the policy of light taxation by freezing land tax rates and practicing universal tax exemption. What prevailed in the Qing fiscal system thus was a ＂low-level equilibrium,＂ in which the fixed amount of revenues was sufficient to cover the state＇s fixed amount of regular expenditures and generate a sizeable amount of surpluses.展开更多
Calculating the spatial structures of ion crystals is important in ion-trapped quantum computation. Here we demon- strate that the simulated annealing method is a powerful tool to evaluate the structures of ion crysta...Calculating the spatial structures of ion crystals is important in ion-trapped quantum computation. Here we demon- strate that the simulated annealing method is a powerful tool to evaluate the structures of ion crystals. By calculating equilibrium positions of 10 ions under harmonic potential and those of 120 ions under anharmonic potential, both with the standard procedure and simulated annealing method, we find that the standard procedure to evaluate spatial structures is complicated and may be inefficient in some cases, and that the simulated annealing method is more favorable.展开更多
Poverty alleviation of the rural poor is the most arduous task in building a moderately prosperous society in all respects in China, and agricultural insurance is an important financial tool for this task. Due to diff...Poverty alleviation of the rural poor is the most arduous task in building a moderately prosperous society in all respects in China, and agricultural insurance is an important financial tool for this task. Due to different capital levels, individual farmer will adopt production technology with different efficiency. In the case of uncertain price of agricultural products, this paper establishes a series of multiple equilibrium models based on agricultural risk and agricultural insurance. Under the catastrophe risk, the probability of falling into the poverty trap is calculated, and the effects of agricultural insurance on poverty alleviation are discussed respectively. It is found that agricultural insurance can effectively reduce the probability of falling into the poverty trap for the farmers whose initial capital is greater than a certain critical value. While the government subsidizes the premium of agricultural insurance by a certain proportion, the effect on poverty alleviation will be further improved.展开更多
Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskit...Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskite solar cells(PSCs)using the one-step spin-coating method.Here,we strategically employed sparingly soluble germanium iodide as a homogenized bulk in-situ reconstruction inducing material preferentially aggregated at the perovskite buried interface with gradient doping,markedly reducing deep-level traps and withstanding local lattice strain,while minimizing non-radiative recombination losses and enhancing the charge carrier lifetime over 9μs.Furthermore,this gradient doping assisted in modifying the band diagram at the buried interface into a desirable flattened alignment,substantially mitigating the energy loss of charge carriers within perovskite films and improving the carrier extraction equilibrium.As a result,the optimized device achieved a champion power conversion efficiency of 25.24% with a fill factor of up to 84.65%,and the unencapsulated device also demonstrated excellent light stability and humidity stability.This work provides a straightforward and reliable homogenization strategy of perovskite components for obtaining efficient and stable PSCs.展开更多
文摘The assumption of the local equilibrium of hydrogen distribution in metals[1]was used in the model formerly developed[2]to describe the diffu- sion of hydrogen in metals.From the assumption a direct relationship between the hydrogen diffusivity and the hydrogen concentration in metals is estab- lished as D=D_o/{1+N_x(k/p)/[1+C(k/p)]} The comparison between the two results drawn from the assumption of equilibrium and the dynam- ics of hydrogen trapping[3]was also presented.The computation results well explained the scattering phenomenon existed in hydrogen diffusion data and suggested that the experimental conditions should be identical for the study of hydrogen permeation in metals.
文摘This article questions the recent scholarship that attempts to draw parallels between Qing China before 1800 and the so-called fiscal-military states in early modem Europe. Beginning with a survey of＂fiscal cycles＂ in China from the 1640s to the 1850s, the author argues that border wars and territorial expansion had little impact on the Qing state＇s tax system and bureaucracy. Contrary to the high level of taxation necessitated by escalation in military spending among the contemporary European states, the Qing pursued the policy of light taxation by freezing land tax rates and practicing universal tax exemption. What prevailed in the Qing fiscal system thus was a ＂low-level equilibrium,＂ in which the fixed amount of revenues was sufficient to cover the state＇s fixed amount of regular expenditures and generate a sizeable amount of surpluses.
基金supported by the National Basic Research Program of China(Grant No.2016YFA0301903)the National Natural Science Foundation of China(Grant Nos.11304387,11174370,61632021,61205108,and 11305262)the Research Plan Project of National University of Defense Technology(Grant No.ZK16-03-04)
文摘Calculating the spatial structures of ion crystals is important in ion-trapped quantum computation. Here we demon- strate that the simulated annealing method is a powerful tool to evaluate the structures of ion crystals. By calculating equilibrium positions of 10 ions under harmonic potential and those of 120 ions under anharmonic potential, both with the standard procedure and simulated annealing method, we find that the standard procedure to evaluate spatial structures is complicated and may be inefficient in some cases, and that the simulated annealing method is more favorable.
文摘Poverty alleviation of the rural poor is the most arduous task in building a moderately prosperous society in all respects in China, and agricultural insurance is an important financial tool for this task. Due to different capital levels, individual farmer will adopt production technology with different efficiency. In the case of uncertain price of agricultural products, this paper establishes a series of multiple equilibrium models based on agricultural risk and agricultural insurance. Under the catastrophe risk, the probability of falling into the poverty trap is calculated, and the effects of agricultural insurance on poverty alleviation are discussed respectively. It is found that agricultural insurance can effectively reduce the probability of falling into the poverty trap for the farmers whose initial capital is greater than a certain critical value. While the government subsidizes the premium of agricultural insurance by a certain proportion, the effect on poverty alleviation will be further improved.
基金supported by the National Natural Science Foundation of China(62105292)Shaanxi Fundamental Science Research Project for Mathematics and Physics(22JSY015)+3 种基金Young Talent Fund of Xi’an Association for Science and Technology(959202313020)the Natural Science Foundation of Shaanxi Province(2021GXLH-Z-0 and 2020JZ-02)the project of Innovative Team of Shaanxi Province(2020TD-001)the China Fundamental Research Funds for the Central Universities。
文摘Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskite solar cells(PSCs)using the one-step spin-coating method.Here,we strategically employed sparingly soluble germanium iodide as a homogenized bulk in-situ reconstruction inducing material preferentially aggregated at the perovskite buried interface with gradient doping,markedly reducing deep-level traps and withstanding local lattice strain,while minimizing non-radiative recombination losses and enhancing the charge carrier lifetime over 9μs.Furthermore,this gradient doping assisted in modifying the band diagram at the buried interface into a desirable flattened alignment,substantially mitigating the energy loss of charge carriers within perovskite films and improving the carrier extraction equilibrium.As a result,the optimized device achieved a champion power conversion efficiency of 25.24% with a fill factor of up to 84.65%,and the unencapsulated device also demonstrated excellent light stability and humidity stability.This work provides a straightforward and reliable homogenization strategy of perovskite components for obtaining efficient and stable PSCs.
