摘要：The design of optimal heterogeneous catalysts for N_(2)-to-NH_(3) conversion is often dictated by the scaling relations,which result in a volcano curve that poses a limit on the catalytic ***,we reveal a bowl active site that can break the scaling relations,through investigating the catalytic mechanisms of N_(2)-to-NH_(3) conversion on the lanthanide intermetallic electride catalyst LaRuSi by first-principles *** bowl active site,composed of four surface La cations and one subsurface Si atom rich in electrons,plays the key role in enabling efficient *** adaptive electrostatic and orbital interactions,the bowl active site promotes the adsorption and activation of N_(2) that delivers facile cleavage of N-N bond,while destabilizes the adsorptions of ^(*)NH_(x)(x=1,2,3)species,which facilitates the release of the final NH_(3) *** comparison with other electride catalysts isostructural to LaRuSi,we confirm the breaking of scaling relations between the adsorptions of ^(*)NH_(x) species and that of^(*)N on the bowl active ***,this bowl active site presents a design concept that breaks the scaling relations for highly efficient heterogeneous catalysis of N_(2)-to-NH_(3) conversion.

摘要：Single-atom catalysts(SACs),including metalmetal-bonded bimetallic ones named single-atom alloys(SAAs),have aroused significant interest in *** this article,the catalytic mechanism and bonding analysis of CO oxidation reaction on bimetallic gold–palladium(Au–Pd)model of single atom alloy Au37Pd1 are investigated by using quantum chemical *** molecular geometries and adsorbate/substrate binding energies of CO@Au–Pd,O2@Au–Pd and CO/O2@Au–Pd configurations are *** core-shell structure is confirmed to be the most stable structure for Au–Pd SAA,where the Pd atom prefers to situate at the core *** transfer from the Pd atom to the Au atoms has been confirmed to stabilize the *** to the binding energy and chemical bonding analysis,both CO and O2 prefer to bind to the Pd atom at the hex site with low coordination *** formation of new co-adsorption species is identified,in which vertical and parallel bridging adsorptions of CO and O2 on the Au–Pd bonds are *** oxidation on Au–Pd SAA is found to be feasible with low energy barriers and follows the Langmuir-Hinshewood(L-H)*** work offers insights into the significant role of single atom of the SAAs in catalytic reactions and can provide evidence for designing new SAAs with high-performance catalytic activities.

摘要：We report herein a new sulfur-functionalized MXene Ti_(2)C(Ti_(2)CS_(2))-supported osmium-metal single-atom catalyst(SAC) Os_(1)/Ti_(2)CS_(2)with high low-temperature catalytic activity for CO oxidation. Using periodic density functional theory calculations, the most stable SAC, Os_(1)/Ti_(2)CS_(2), has been screened from a series of group 8–11 transition metal SACs M_(1)/Ti_(2)CS_(2)(M = Fe, Co, Ni, Cu;Ru, Rh, Pd, Ag;Os, Ir,Pt, Au). The calculations show that it is favorable for O;and CO to be coadsorbed on the Os;single atom(SA) of Os_(1)/Ti_(2)CS_(2)and the adsorption energy of the first O_(2) molecule is slightly higher than that of CO. Moreover, the termolecular co-adsorption of O_(2)+ 2CO on Os_(1) SA is also possible, which is favorable for CO oxidation on Os_(1) SA through a novel threemolecule reaction mechanism. Accordingly, four different catalytic mechanisms, the Langmuir–Hinshelwood(L–H),Eley–Rideal(E–R), termolecular Langmuir–Hinshelwood-A(TLH-A) and termolecular Langmuir–Hinshelwood-B(TLHB), are systematically studied for CO oxidation by O_(2) on Os_(1)/Ti_(2)CS_(2). The theoretical studies indicate that the TLH-B mechanism is the most feasible for CO oxidation with the reaction barrier energy of only 0.74 e V, which is far lower than for L–H, E–R and TLH-A with barrier energies of 1.06, 1.09 and1.47 e V, respectively. The results provide fundamental understanding to the surface chemistry of MXene and designing new sulfur-functionalized two-dimensional MXene catalytic nanomaterials.

摘要：在全球气候变暖与城市化进程加快的背景下,城市热环境受到广泛关注。了解城市热环境时空变化和城市空间形态对城市局地气候的影响对于缓解城市热岛效应至关重要。ECOSTRESS在昼夜不同时刻获取高时间分辨率地表温度(Land Surface Temperature,LST)为从精细化时空尺度对城市热环境进行动态评估提供了数据支持。本文基于局地气候区(Local Climate Zones,LCZ)视角,利用ECOSTRESS LST数据探究了北京市六环内夏季地表城市热岛强度(Surface Urban Heat Island Intensity,SUHII)的日尺度时空变化特征以及LCZ类间和类内SUHII差异。结果表明:(1)研究区夏季SUHII具有时空异质性,清晨6时左右,SUHII最低,上午10时左右,SUHII达到最高,下午SUHII逐渐下降,傍晚18时左右开始上升,21时左右达到夜间最高值;(2)在日尺度上,不同类型LCZ表现出显著的热源/汇角色差异。建筑类型LCZ(除LCZ 9)和自然类型LCZ E~F整体上为热源,LCZ 9和LCZ B~C整体上为热汇,LCZ A和LCZ G存在昼夜源汇角色变化;(3) LCZ类内SUHII表现出显著的昼夜和类型差异。LCZ类内SUHII差异在清晨6时左右最小,在下午13时左右达到最大值。建筑类型LCZ中,低层建筑类内SUHII差异总体上高于中高层建筑。自然类型LCZ中,LCZ C和LCZ E类内SUHII差异相对较小,而LCZ D、LCZ F和LCZ G类内SUHII差异相对较大;(4) LCZ类型表现出昼夜不同的热特性和源汇角色变化。LCZ G存在昼夜源汇变化,夜间呈现出明显的城市热源特性。本文所采用的10个时刻的ECOSTRESS LST数据克服了以往利用单一固定时刻的LST数据对于SUHII的高估和低估,所得到的LCZ类间和类内SUHII差异对比结果降低了城市热环境定量研究的不确定性,并为城市热环境源汇景观设计的昼夜权衡提供了理论依据和实践支持。

摘要：为提升车辆通行效率,以预测型诱导策略为基础,以排队长度作为交通诱导的约束条件,利用小波神经网络短时交通量预测预知路段堵死事件发生路段,通过广域诱导时空边界条件对事件路段进行节点分级和诱导周期长度界定,进而建立广域诱导模型;对事件区域路网进行分区,进一步确定该模型诱导起点位置,引入基于路径尺度的Logit路径选择模型作为诱导路径选择方法,通过流量迭代分配方法实现路网负载均衡.通过实例验证,该诱导方法能有效地缓解道路交通拥堵,提高路网通行效率.

摘要：为满足市场上对各类纬编产品的设计需求,基于CAD技术对纬编针织物设计系统的开发作进一步研究。结合组织设计特点分别建立编织图、意匠图数学模型,采用二维、三维矩阵模型表示相应的数据信息。此外,针对织针排列图、三角配置图的数学表达以及花色意匠图到结构意匠图的转换算法进行说明,并详细描述其具体的实现过程。在此理论基础上,利用Visual C++设计平台开发了CKCAD1.0纬编针织物设计系统,实现了工艺设计的功能,使得纬编产品的设计更为直观、快速、准确。

摘要：为研究冰爽涤纶无缝内衣面料的热湿舒适性,从原料组合、组织结构因素考虑,共设计了16款试样作对比。其中8款含有冰爽涤纶成分,其余为常规面料。针对这些试样进行透湿、导湿、吸水、蒸发速干、保暖性能的测试。并基于试验数据结果,运用模糊综合法对面料的热湿舒适性能进行评价。结果表明,冰爽涤纶无缝内衣面料具有较为优良的散热性能、透湿性能、导湿性能、蒸发速干性能,特别是冰爽涤纶用作地纱,适合用作夏季无缝内衣面料。

摘要：为研究掺钢纤维无配筋超高性能混凝土(UHPC)矩形梁的抗扭性能,分析钢纤维类型对梁体纯扭受力行为的影响,设计制作4根UHPC矩形梁[包括未掺钢纤维试件1根;掺短圆直、长圆直、端钩钢纤维试件各1根(钢纤维长分别为13,20,13 mm,直径均为0.2 mm,体积掺量均为2%)],并设计1套纯扭加载装置进行试件纯扭试验。基于试验结果,分析各试件在纯扭作用下的扭矩~扭率曲线、开裂和极限扭矩、扭矩~应变曲线、裂缝分布等,并推导UHPC矩形梁的抗扭承载力计算公式,将计算值与试验值进行对比验证。结果表明:掺入钢纤维使UHPC试件由脆性破坏变为延性破坏,且开裂和极限扭矩均有明显提升,最大提升幅度分别为45.6%和100.6%;当体积掺量不变时,钢纤维类型对无配筋UHPC梁开裂扭矩和扭率影响较小,但对极限扭矩和扭率以及裂缝分布有较大影响;掺端钩纤维试件和掺长圆直纤维试件的抗扭承载力和延性均优于掺短圆直纤维试件;掺钢纤维UHPC梁在纯扭作用下的主拉和主压应变显著高于未掺试件,表明钢纤维可以有效“桥联”UHPC基体;试件的抗扭承载力试验值和计算值比值的平均值为0.93,标准差为0.09,说明提出的抗扭承载力计算公式具有良好的精度。建议实际工程中的无筋或少筋UHPC构件采用端钩或长圆直纤维,以改善结构的抗扭延性和裂后承载力。

摘要：已有的激光图形显示系统太单调,图形显示不灵活,不能体现激光应有的显示功能。提出了一个基于计算机控制的多通道激光图形显示系统,该系统通过分光控制完成了振镜、转镜和步镜的协调工作,更好地展现了3种不同功能的电机工作模式,解决了分光系统中电机的响应失真问题,从而丰富和完善了激光图形显示功能。改进后的激光图形显示系统的试验结果表明,多通道激光图形显示系统提高了图形质量,使显示更便利,内容更丰富。

摘要：在Ge-Se二元体系中引入相同摩尔比的Ga,Sn,Sb,Te四种元素,使用熔融淬冷法制备了一系列硫系玻璃.利用吸收光谱获得了不同元素引入下硫系玻璃能带结构的变化,并结合拉曼光谱详细研究了产生光学特性变化的微观表征.使用Z扫描方法测试了各个硫系玻璃样品在1550 nm波长下的三阶非线性参数,发现加入Sn的玻璃的三阶非线性折射率n2最大,达到了6.36×10 17m2/W,且其品质因子大于23,表明Sn引入能够增强硫系玻璃在通信波段的三阶非线性,这一研究结果为以后的高性能红外器件的设计及制备提供了一种环保且性能优良的候选材料.