为了研究不同经验驾驶人在高速公路特长隧道环境下的注视转移特性,在高速公路特长隧道中开展实车实验,利用i View X HED型眼动仪采集了32名不同经验驾驶人的眼动数据。运用动态聚类方法,对驾驶人注视区域进行划分,分析了职业与非职业驾...为了研究不同经验驾驶人在高速公路特长隧道环境下的注视转移特性,在高速公路特长隧道中开展实车实验,利用i View X HED型眼动仪采集了32名不同经验驾驶人的眼动数据。运用动态聚类方法,对驾驶人注视区域进行划分,分析了职业与非职业驾驶员在高速公路隧道不同段与普通路段的注视转移规律与注意力分配特性。结果表明:相较于非职业驾驶人,职业驾驶员具有较强的注视前瞻性,且在隧道的不同段主要注视的区域因行车环境不同变化较小;驾驶人对同一目标需要重复注视才能提取足够的信息,且当行车环境复杂度增加或驾驶员驾驶经验不足时,重复注视概率增加;驾驶人在不同路段行车时,主要通过注视中间区域获取信息;行车环境与驾驶经验对驾驶人在中间近处、左侧区域及内后视镜区域的注视平稳分布存在显著的交互作用。展开更多
Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recen...Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recently theoretically predicted to be a new class of potential NRR catalysts,but direct experimental evidence is still lacking.Herein,we present the first experimental demonstration that amorphous FeB_2 porous nanosheets(a-FeB_2 PNSs) could be a highly efficient NRR catalyst,which exhibited an NH3 yield of 39.8 μg h^(-1) mg^(-1)(-0.3 V) and a Faradaic efficiency of 16.7%(-0.2 V),significantly outperforming their crystalline counterpart and most of existing NRR catalysts.First-principle calculations unveiled that the amorphization could induce the upraised d-band center of a-FeB_2 to boost d-2π~* coupling between the active Fe site and ~*N_2 H intermediate,resulting in enhanced ~*N_2 H stabilization and reduced reaction barrier.Out study may facilitate the development and understanding of earth-abundant TMB_2-based catalysts for electrocatalytic N_2 fixation.展开更多
A carboxylative coupling reaction of various primary amine and 3-phenyl-2-propynyl or 2-nonynyl chloride in the presence of 8-diazabicyclo[5.4.0]undec-7-ene(DBU)using carbon dioxide as carboxylative reagent was presen...A carboxylative coupling reaction of various primary amine and 3-phenyl-2-propynyl or 2-nonynyl chloride in the presence of 8-diazabicyclo[5.4.0]undec-7-ene(DBU)using carbon dioxide as carboxylative reagent was presented.This transition-metal free reaction system shows broad substrate scope and gives a series of propargylcarbamates in moderate to good yield.The obtained N-alkyl substituted carbamate product can undergo base-catalyzed intramolecular cyclization reaction to afford functionalized 4-methylene-2-oxazolidinone in good yield.展开更多
为了分析草原公路行车环境常见随机风险点驾驶人的动态视觉特征,将随机风险点按照相对位置及所处状态进行分类,选取14名驾驶人开展典型草原公路实驾试验,使用I view X HED眼动仪同步采集驾驶人的眼动数据,对比分析驾驶人行经不同类别风...为了分析草原公路行车环境常见随机风险点驾驶人的动态视觉特征,将随机风险点按照相对位置及所处状态进行分类,选取14名驾驶人开展典型草原公路实驾试验,使用I view X HED眼动仪同步采集驾驶人的眼动数据,对比分析驾驶人行经不同类别风险点的注视时长、注视次数及注视点转移特征及差异性。研究结果表明,驾驶人在有随机风险的情形下平均注视时长均较长,且在路内停车风险点处注视时长最长,超车切入与路侧动物风险点相近,路侧停车次之,注视次数规律则相反。一旦出现随机风险时,驾驶人除了将道路区域作为主要获取信息区域外,还会选择风险点所处的区域作为辅助区域来补充信息的获取,且对处于运动状态的风险关注程度更多。在路内随机风险点驾驶人注视区域相对集中,视觉转移路径较单一,而在路侧随机风险点,驾驶人的注视区域广,注视转移路径分散,无序性增加,带来的视觉负荷更大。展开更多
文摘为了研究不同经验驾驶人在高速公路特长隧道环境下的注视转移特性,在高速公路特长隧道中开展实车实验,利用i View X HED型眼动仪采集了32名不同经验驾驶人的眼动数据。运用动态聚类方法,对驾驶人注视区域进行划分,分析了职业与非职业驾驶员在高速公路隧道不同段与普通路段的注视转移规律与注意力分配特性。结果表明:相较于非职业驾驶人,职业驾驶员具有较强的注视前瞻性,且在隧道的不同段主要注视的区域因行车环境不同变化较小;驾驶人对同一目标需要重复注视才能提取足够的信息,且当行车环境复杂度增加或驾驶员驾驶经验不足时,重复注视概率增加;驾驶人在不同路段行车时,主要通过注视中间区域获取信息;行车环境与驾驶经验对驾驶人在中间近处、左侧区域及内后视镜区域的注视平稳分布存在显著的交互作用。
基金supported by the National Natural Science Foundation of China (51761024)the CAS ‘‘Light of West China” Program, ‘‘Feitian Scholar” Program of Gansu Provincethe Foundation of A Hundred Youth Talents Training Program of Lanzhou Jiaotong University。
文摘Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recently theoretically predicted to be a new class of potential NRR catalysts,but direct experimental evidence is still lacking.Herein,we present the first experimental demonstration that amorphous FeB_2 porous nanosheets(a-FeB_2 PNSs) could be a highly efficient NRR catalyst,which exhibited an NH3 yield of 39.8 μg h^(-1) mg^(-1)(-0.3 V) and a Faradaic efficiency of 16.7%(-0.2 V),significantly outperforming their crystalline counterpart and most of existing NRR catalysts.First-principle calculations unveiled that the amorphization could induce the upraised d-band center of a-FeB_2 to boost d-2π~* coupling between the active Fe site and ~*N_2 H intermediate,resulting in enhanced ~*N_2 H stabilization and reduced reaction barrier.Out study may facilitate the development and understanding of earth-abundant TMB_2-based catalysts for electrocatalytic N_2 fixation.
基金National Natural Science Foundation of China(No.21172026)Scientific Research Fund of Liaoning Provincial Education Department(No.L2012024)X.-B.L.gratefully acknowledges the Chang Jiang Scholars Program(No.T2011056)from Ministry of Education of the People's Republic of China.
文摘A carboxylative coupling reaction of various primary amine and 3-phenyl-2-propynyl or 2-nonynyl chloride in the presence of 8-diazabicyclo[5.4.0]undec-7-ene(DBU)using carbon dioxide as carboxylative reagent was presented.This transition-metal free reaction system shows broad substrate scope and gives a series of propargylcarbamates in moderate to good yield.The obtained N-alkyl substituted carbamate product can undergo base-catalyzed intramolecular cyclization reaction to afford functionalized 4-methylene-2-oxazolidinone in good yield.
文摘为了分析草原公路行车环境常见随机风险点驾驶人的动态视觉特征,将随机风险点按照相对位置及所处状态进行分类,选取14名驾驶人开展典型草原公路实驾试验,使用I view X HED眼动仪同步采集驾驶人的眼动数据,对比分析驾驶人行经不同类别风险点的注视时长、注视次数及注视点转移特征及差异性。研究结果表明,驾驶人在有随机风险的情形下平均注视时长均较长,且在路内停车风险点处注视时长最长,超车切入与路侧动物风险点相近,路侧停车次之,注视次数规律则相反。一旦出现随机风险时,驾驶人除了将道路区域作为主要获取信息区域外,还会选择风险点所处的区域作为辅助区域来补充信息的获取,且对处于运动状态的风险关注程度更多。在路内随机风险点驾驶人注视区域相对集中,视觉转移路径较单一,而在路侧随机风险点,驾驶人的注视区域广,注视转移路径分散,无序性增加,带来的视觉负荷更大。
