摘要：Tailoring the microstructure of pristine TiO2 is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry, electronic structure, and morphology of TiO2 photocatalysts to improve their photocatalytic activity based on the strong complexation between fluoride ions and TiO2 and the high electronegativity of fluorine. In this review, we summarize the strategies involving fluorine to establish highly efficient TiO2 photocatalytic systems or fabricate highly efficient TiO2 photocatalysts. The main fluorine effects(i.e. the effects of fluorine on photocatalysis) include the following four aspects:(1) Surface effects of fluoride on TiO2 photocatalysis,(2) effects of fluorine doping on TiO2 photocatalysis,(3) fluoride-mediated tailoring of the morphology of TiO2 photocatalysts, and(4) the effects of fluorine on non-TiO2 photocatalysis. Additionally, the unique applications of these fluorine effects in photocatalysis, including selective degradation of pollutants, selective oxidation of chemicals, water-splitting to produce H2, reduction of CO2 to produce solar fuels, and improvement of the thermostability of TiO2 photocatalysts, are reviewed.

摘要：The development of well-defined TiO2 nanoarchitectures is a versatile strategy to achieve high-efficiency photocatalytic *** this study,mesoporous TiO2 nanofibers consisting of oriented nanocrystals were fabricated by a facile vapothermal-assisted topochemical transformation of preformed H-titanate *** vapothermal temperature is crucial in tuning the microstructures and photocatalytic redox properties of the resulting mesoporous TiO2 *** microstructures were characterized with XRD,TEM,XPS and nitrogen adsorption-desorption isotherms,*** photocatalytic activities were evaluated by photocatalytic oxidation of organic pollutant(Rhodamine B as an example)as well as photocatalytic reduction of water to generate hydrogen(H2).The nanofibers vapothermally treated at 150°C showed the highest photocatalytic activity in both oxidation and reduction reactions,2 times higher than that of *** oriented alignment and suitable mesoporosity in the resulting nanofiber architecture were crucial for enhancing photocatalytic *** oriented alignment of anisotropic anatase nanocrystals shall facilitate faster vectorial charge transportation along the nanofibers ***,the suitable mesoporosity and high surface area would also effectively enhance the mass exchange during photocatalytic *** also demonstrate that efficient energy-recovering photocatalytic water treatments could be accomplished by a cascading oxic-anoxic process where the dye is degraded in the oxic phase and hydrogen is generated in the successive anoxic *** study showcases a novel and facile method to fabricate mesoporous TiO2 nanofibers with high photocatalytic activity for both clean energy production and environmental purification.

摘要：沥青路面回收料(reclaimed asphalt pavement,RAP)的再利用可以减少天然集料的消耗、降低环境污染,但高RAP掺量的再生沥青混合料(recycled asphalt mixture,RAM)存在着路用性能不足的问题,需要提高RAP的利用效果和质量。文中采用RAP和钢渣集料取代天然集料,以环氧沥青作为胶结料,制备钢渣RAM。设计不同RAP掺量的RAM,在最佳油石比条件下,对RAM的体积性能、力学性能、抗水损害性能、高温抗车辙性能及抗滑性能进行研究。对比研究不同RAP掺量、不同固化温度及时间下,RAM的路用性能变化规律。结果表明,钢渣集料和环氧沥青胶结料有利于提高RAM的力学性能、抗水损害性能,并显著提高抗车辙性能。在120℃下保温5 d后,RAM-40比RAM-100的马歇尔稳定度高30.2%,3种RAM的动稳定度均超过8000次/mm。

摘要：为了研究木材表面初始损伤对碳纤维增强树脂复合材料(CFRP)-木材界面粘结性能的影响,以木材表面初始损伤率为变量,设计了4组(共12个)CFRP-木材双面剪切试件,分析了初始损伤对粘结界面破坏形态、荷载-应变曲线、应变分布曲线及界面承载力等力学性能的影响规律,探讨了木材初始损伤对界面力学性能的影响机制。试验结果表明:木材表面存在的初始损伤改变了CFRP-木材界面的破坏形态,随着损伤率的增加,剪切破坏面进入木材基体的深度逐渐变浅,界面的脆性破坏特征越显著;木材表面的初始损伤截断了木材纤维,破坏了木材表面的完整性,削弱了界面应力传递效率,增加了界面应力集中现象,使界面粘结承载力随着损伤率的增加而不断降低。本文通过对粘结界面微段的受力分析,推导了极限状态下界面应力分布计算表达式,建立了考虑木材表面初始损伤影响的CFRP-木材界面粘结承载力模型,界面粘结承载力预测模型的计算结果与试验结果的误差均小于6%,吻合较好。

摘要：针对低轨星座卫星快速开发与验证需求,提出试验星+工程星+接口验证平台(VPI)并行研制验证方案。通过工程星研制,对卫星结构、总装设计及供电主通道、推进贮供主通道等设计进行验证,支撑试验星设计优化与结构投产;VPI对星上电子单机接口、星上软件等进行迭代验证。通过试验星研制,对低轨星座卫星功能性能全面验证,确定星座卫星基线。该方案经多颗卫星实施验证,有效提高了低轨星座卫星验证效率。

摘要：为了研究FRP筋再生混凝土(RAC)梁受弯性能,试验制作八根FRP筋再生混凝土梁(其中GFRP筋和BFRP筋再生混凝土梁的数量分别为六根和两根),通过四点弯曲试验研究再生骨料(RA)替代率与FRP筋类型对梁破坏模式、挠度和承载力等性能的影响。试验结果表明:(1)梁的开裂荷载和极限承载力均随着再生骨料替代率的增加而下降,且破坏模式也逐渐由正截面混凝土受压破坏转为斜拉破坏;(2)BFRP筋弹性模量的提高使梁的混凝土受压区高度增加,正截面承载力增加,而斜截面承载力提高较少,从而使BFRP筋再生混凝土梁发生斜拉破坏;(3)规范计算得到的FRP筋再生混凝土梁承载力安全储备略显不足,建议实际配筋率为平衡配筋率ρfb的1~1.5倍时,设计值取规范计算值的0.8倍;(4)GB与ACI挠度计算值均与试验值拟合程度较好,能很好地预测FRP筋再生混凝土梁的挠度值。

摘要：双频Buck变换器由两个降压单元级联构成,具有动态响应快,开关损耗小等优势。然而不足的是磁件占据了整个系统的大部分体积与重量,降低了系统的功率密度。针对这一问题,提出一种三段式绕制磁集成技术,将磁件以解耦的方式集成在一副磁心中。该文首先建立集成磁件的磁路等效模型,通过抵消各绕组之间的耦合作用推导出解耦条件,并详细阐述了磁心的选取、匝数以及气隙的设计原则。其次,利用有限元仿真平台对所提集成磁件进行建模分析,与现有的集成方法相比,磁通密度分布更为均匀,磁心的利用率得到了有效提升。最后,搭建一台48 V/12 V、108 W的实验样机,体积和重量同分离磁件相比降低了31.2%和25.3%,提高了系统的功率密度,验证了该集成方法理论分析的正确性和可行性。

摘要：Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by scanning electron microscopy,X-ray diffraction,N2 adsorption,X-ray photoelectron spectroscopy,UV-visible spectroscopy,and electrochemical impedance spectroscopy. Their photocatalytic activity was evaluated using the photocatalytic reduction of CO2. The N-doped TiO 2 sample exhibited a much higher visible light photocatalytic activity for CO2 reduction than its precursor TiN and commercial TiO 2（P25）. This was due to the synergistic effect of the formation of surface heterojunctions on the TiO 2 microsheet surface,enhanced visible light absorption by nitrogen-doping,and surface fluorination.

摘要：哈希函数在区块链中扮演着安全基石的重要角色,对区块链系统中共识机制的构建和数据完整性保护发挥着不可替代的作用.然而随着量子技术的加速发展,量子计算机的出现将对经典哈希函数构成严重安全威胁,基于量子算法的并行计算特性,Grover量子算法在寻找哈希冲突时较经典搜索算法能提供2次加速,从而能有效实施针对经典哈希函数的量子计算攻击,例如挖矿攻击、伪造攻击,对区块链的安全构成严重挑战.阐述了哈希函数的抗原像性、弱抗碰撞性及强抗碰撞性,分析了针对经典哈希函数的量子计算攻击主要形式:原像攻击和第二原像攻击.从抗量子安全的角度对区块链中的哈希函数展开比较研究,从构造、输入、输出、优点、缺点等方面出发,对5类典型哈希算法进行分析与对比,并对区块链中的哈希函数提出设计建议,为后量子时代区块链中的哈希函数的设计提供有益参考.

摘要：中国城市处于面临转型升级的重要时期,城市更新在城市建设中扮演着越来越重要的角色.在理论和实践中不断成熟的绿道,也逐渐成为城市更新的重要手段之一.首先以奥姆斯特德建立的波士顿绿链的发展为例,分析绿道在不同城市发展时期的特点,然后以滨水空间和交通灰空间2种城市更新的类型,总结城市绿道在区域城市发展带动、激活城市灰空间、绿色基础设施等方面的作用,并以三亚月川绿道为例介绍我国绿道在城市更新中的初步实践.最后总结思考未来城市更新中绿道的实践方向.