A novel approach based on the upper bound theory is proposed to assess the stability of excavated slopes with spatially variable clay in undrained conditions.The proposed random limit analysis is a combination of the ...A novel approach based on the upper bound theory is proposed to assess the stability of excavated slopes with spatially variable clay in undrained conditions.The proposed random limit analysis is a combination of the deterministic slope stability limit analysis together with random field theory and Monte Carlo simulation.A series of analyses is conducted to verify the potential application of the proposed method and to investigate the effects of the soil undrained shear strength gradient and the spatial correlation length on slope stability.Three groups of potential sliding surfaces are identified and the occurrence probability of each sort of failure mechanism is quantified for various slope ratios.The proposed method is found to be feasible for evaluating slope reliability.The obtained results are helpful in understanding the slope failure mechanism from a quantitative point of view.The paper could provide guidance for slope targeted local reinforcement.展开更多
Novel trivalent europium(Eu^(3+))-activated La_(7)Ta_(3)W_(4)O_(30):xEu^(3+)(x=0.5 mol%-40 mol%) red-emitting phosphors were synthesized by means of a high-temperature solid-state reaction.The structure,morphology,pho...Novel trivalent europium(Eu^(3+))-activated La_(7)Ta_(3)W_(4)O_(30):xEu^(3+)(x=0.5 mol%-40 mol%) red-emitting phosphors were synthesized by means of a high-temperature solid-state reaction.The structure,morphology,photoluminescence,thermal-stability properties,lifetime,and color-rendering of the prepared phosphors were investigated in detail.The La_(7)Ta_(3)W_(4)O_(30):Eu^(3+) phosphors show five emission peaks under near-ultraviolet(n-UV) at 397 nm,and these peaks are ascribed to the transitions of ^(5)D0-^(7)Fj(j=0,1,2,3 and 4) by Eu^(3+) ions.The optimal doping concentration of Eu^(3+) is 20 mol%,and the critical distance of the energy transfer between the Eu^(3+)ions was calculated to be 1.768 nm.The quenching temperature(T_(0.5)) of La_(7)Ta_(3)W_(4)O_(30):20 mol%Eu^(3+) is about 440 K.The quantum yield(QY) was measured to be 85.85%.The fabricated white-light-emitting diodes(w-LEDs) possess high color-rendering index(R_(a)) of 90,and high correlated color temperature(CCT) of 5810 K,respectively.The Commission Internationale de L’Eclairage(CIE) coordinates are(0.311,0.322).Therefore,the prepared phosphor has a promising application for w-LEDs.展开更多
基金the National Natural Science Foundation of China(Grant No.52322808)the QingLan Project of Jiangsu Province of China.
文摘A novel approach based on the upper bound theory is proposed to assess the stability of excavated slopes with spatially variable clay in undrained conditions.The proposed random limit analysis is a combination of the deterministic slope stability limit analysis together with random field theory and Monte Carlo simulation.A series of analyses is conducted to verify the potential application of the proposed method and to investigate the effects of the soil undrained shear strength gradient and the spatial correlation length on slope stability.Three groups of potential sliding surfaces are identified and the occurrence probability of each sort of failure mechanism is quantified for various slope ratios.The proposed method is found to be feasible for evaluating slope reliability.The obtained results are helpful in understanding the slope failure mechanism from a quantitative point of view.The paper could provide guidance for slope targeted local reinforcement.
基金Project supported by the Fundamental Research Funds for the Central Universities(2452019076)Undergraduate Innovation Fund of Northwest A&F University+4 种基金China(201910712037)Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the Key Discipline in Hunan Provincethe Projects of the Education Department of Hunan Province(18A465)Science and Technology Plan Project of Chenzhou City(jsyf2017014)。
文摘Novel trivalent europium(Eu^(3+))-activated La_(7)Ta_(3)W_(4)O_(30):xEu^(3+)(x=0.5 mol%-40 mol%) red-emitting phosphors were synthesized by means of a high-temperature solid-state reaction.The structure,morphology,photoluminescence,thermal-stability properties,lifetime,and color-rendering of the prepared phosphors were investigated in detail.The La_(7)Ta_(3)W_(4)O_(30):Eu^(3+) phosphors show five emission peaks under near-ultraviolet(n-UV) at 397 nm,and these peaks are ascribed to the transitions of ^(5)D0-^(7)Fj(j=0,1,2,3 and 4) by Eu^(3+) ions.The optimal doping concentration of Eu^(3+) is 20 mol%,and the critical distance of the energy transfer between the Eu^(3+)ions was calculated to be 1.768 nm.The quenching temperature(T_(0.5)) of La_(7)Ta_(3)W_(4)O_(30):20 mol%Eu^(3+) is about 440 K.The quantum yield(QY) was measured to be 85.85%.The fabricated white-light-emitting diodes(w-LEDs) possess high color-rendering index(R_(a)) of 90,and high correlated color temperature(CCT) of 5810 K,respectively.The Commission Internationale de L’Eclairage(CIE) coordinates are(0.311,0.322).Therefore,the prepared phosphor has a promising application for w-LEDs.
