摘要：针对混凝土衬砌渠道容易在季节变化期间发生冻胀情况,影响其正常使用的问题,研究以北方某“U”形混凝土衬砌渠道为例,分析了混凝土衬砌渠道的冻胀影响因素。试验结果显示,渠基土冻深和极值负积温是混凝土衬砌渠道的冻胀影响因素。研究为农田水利工程中混凝土衬砌渠道的设计和施工提供了参考,有利于农业经济发展。

摘要：辽宁省某大坝外坡工程受雨水冲刷的影响,土壤侵蚀严重,水土大量流失。为了保证边坡完整性,维护其安全稳定,研究利用抗冻植被混凝土进行支护。结果表明,抗冻植被混凝土的多孔性质以及交错的根系有利于抵御径流与下渗侵蚀,植草后径流侵蚀最大降幅达90.64%,壤土下渗侵蚀量降低86.1 g/m^(2);坡度增加会加大径流侵蚀,最大增幅219.07%;但坡度增加会降低下渗侵蚀和降雨入渗量。抗冻植被混凝土有效减缓了雨水侵蚀,保证了堤坝稳定性。

摘要：An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.

摘要：Recently, the g-C3N4-based heterojunctions have been widely investigated for their greatly enhanced photogenerated carrier separation efficiency. However, most studies are based on the study of g-C3N4 powders. In this study, a novel TiN/C3N4/CdS nanotube arrays core/shell structure is designed to improve the photoelectrochemical catalytic performance of the g-C3N4-based heterojunctions. Among them, TiN nanotube arrays do not respond to simulated solar light, and thus only serve as an excellently conductive nanotube arrays backbone for supporting g-C3N4/CdS heterojunctions. g-C3N4 prepared by simple liquid atomic layer deposition, which possesses appropriate energy band position, mainly acts as the electron acceptor to transport and separate electrons. Deposited CdS quantum dots obtained by successive ionic layer adsorption reaction can effectively absorb visible light and thus act as a light absorber. The TiN/C3N4/CdS nanotube arrays core/shell structure could be verified by X-ray diffractions, Raman spectra, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy elemental mappings and X-ray photoelectron spectroscopy. Compared with TiN/C3N4 nanotube arrays, the TiN/C3N4/CdS samples greatly improve the photoelectrochemical performance, which can be evaluated by photoelectrochemical tests and photoelectrochemical catalytic degradation. Especially, the optimized photocurrent density of TiN/C3N4/CdS has almost 120 times improvement on TiN/C3N4 at 0 V bias under simulated sunlight, which can be ascribed to the effective expansion of the light absorption range and separation of electron-hole pairs.

摘要：闽南红砖厝是福建闽南地区的传统建筑,布局规模以三开间或是五开间汉式大厝构造为主,硬山顶、双坡曲屋面、燕尾屋脊、红砖墙体、白石基座都是该建筑的基本制式。城市化的推进使闽南红砖厝建筑逐渐减少,除了建筑修复的保护方式以外,可将其视为福建特色的地域符号在设计领域中赋予新生。本文以闽南红砖厝的建筑装饰元素为研究对象,分析闽南红砖厝装饰元素的营造技艺,通过研究其重构和转化的设计手法,在此研究基础上进行家具设计实践。

摘要：实验是化学教学中的关键内容,但目前高中化学实验教学仍存在教学模式陈旧、缺乏系统性、创新性等问题。本文从学生核心素养培养的角度出发,以制作简单的燃料电池为例,结合高中化学实验教学设计和实践,探讨了制作简单的燃料电池的教学创新。研究发现,设计创新实验教学,有利于提高学生化学学习兴趣,提升探究与创新能力。

摘要：基于染料敏化太阳能电池发展起来的有机-无机杂化钙钛矿太阳能电池经过不到5年的快速发展,光电转换效率从最初的3.8%提高到了经过认证的17.9%.但是常用结构的钙钛矿太阳能电池在性能测试过程中的电流-电压(I-V)曲线会随着测试器件扫描方向的不同而明显不同.该现象被称为I-V滞回现象.进一步研究发现I-V曲线还与扫描速度、起始测试的偏压值和光照历史明显相关.本工作结合不同的器件构造,就可能造成这种I-V滞回现象的不同原因进行了总结和分析,并对如何获得可靠的光电转换效率的测试方法进行了评述.

摘要：良好的城市形象是城市发展的助推器。通过全面深入剖析汕头城市形象塑造存在的问题,运用RIS理论,从理念识别、行为识别、视觉识别等三个层次,设计了汕头城市形象“开放、创新、包容”的新内涵,并规划设计、机构设置、行为主体、视觉效果、宣传活动、整合资源、形象评估从等方面提出城市形象新内涵的塑造路径。

摘要：为探索机载弹射发射装置轻量化的有效途径,以发射装置典型结构推臂为研究对象,对碳纤维复合材料应用于该结构的可行性进行了综合论证。利用有限元方法优化结构设计并对结构失效部位进行了预测,通过系列静载试验确认了材料缺陷区及工字梁过渡区为结构薄弱部位,制定了推臂用碳纤维复合材料的工艺改进方案,并通过了极限工况考核。改进工艺后的碳纤维复合材料,其性能满足推臂结构设计要求,与铝合金相比,可实现减重1/3,为该材料在机载弹射发射装置上的推广应用提供了理论指导和试验依据。

摘要：目的了解我国≥15岁人群在过去30 d内看到烟草广告和促销的情况,分析2010与2018年烟草广告和促销的宣传渠道、宣传形式等状况,为进一步推动控烟工作提供依据。方法2010与2018年均采用多阶段分层整群随机抽样,分别抽取≥15岁具有全国代表性的常住居民13354人和19376人。使用SAS 9.4软件对数据进行清洗、加权、分析,采用Rao-Scottχ^(2)检验进行数据单因素组间比较。结果2010与2018年分别有19.61%和18.14%的调查对象看到了烟草广告和促销,两年相比看到烟草广告和促销的情况无明显变化。烟草广告方面,去过销售卷烟商店的人群在销售卷烟商店看到烟草广告的比例从2010年的29.28%上升为2018年的43.28%;看过电视的人群在电视上看到烟草广告的比例从2010年的50.93%下降为2018年的28.58%;去过电影院的人群在电影院看到烟草广告的比例从2010年的2.17%上升为2018年的9.89%;使用过互联网的人群在互联网看到烟草广告的比例从2010年的19.20%上升为2018年的42.30%。烟草促销方面,2010与2018年,人群过去30 d内在各类场所看到烟草促销活动、卷烟价格折扣、卷烟优惠券、免费礼品或其他优惠的比例均有上升,分别为4.99%vs.9.30%、0.78%vs.4.09%、0.04%vs.0.33%和0.98%vs.3.33%,差异有统计学意义(P<0.001)。结论我国烟草广告和促销等情况仍广泛存在,2010与2018年无明显改变。随着媒体平台不断的变化发展,烟草广告和促销的渠道也有所转变,特别是互联网、烟草零售点的烟草广告等应加强重视。需要进一步完善相关政策,全面禁止烟草广告和促销活动,并着力加强监管工作。