摘要：An autonomous approach and landing（A＆L） guidance law is presented in this paper for landing an unpowered reusable launch vehicle（RLV） at the designated runway touchdown. Considering the full nonlinear point-mass dynamics, a guidance scheme is developed in threedimensional space. In order to guarantee a successful A＆L movement, the multiple sliding surfaces guidance（MSSG） technique is applied to derive the closed-loop guidance law, which stems from higher order sliding mode control theory and has advantage in the finite time reaching *** global stability of the proposed guidance approach is proved by the Lyapunov-based *** designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A＆L phase and instantaneous states of the RLV. Therefore, the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase. Finally, simulation results show the effectiveness of the proposed guidance law in different scenarios.

摘要：“Union is strength”.In the realm of organic molecules,the macroscopic performance of molecular aggregates is not just the simple overlay of single molecules,and in many cases,new properties can be created by molecular uniting with particular packing modes[1–4].As to the organic emissive materials,various changes can be rea-lized from single molecules to aggregates(Fig.1),in-cluding the emerged bright emission,the varied emission color,the different emission forms,and the arisen new excitation processes.

摘要：The phenomenon that different molecular packing modes in aggregates result in different optical properties has attracted intense attention,since it can provide useful information to establish the relationship between the micro-and *** this paper,DBTDO-DMAC was designed with 9,10-dihydro-9,9-dimethylacridine(DMAC)as electron ***-DPA and DBTDO-Cz were designed for comparison,which adopted diphenylamine(DPA)with twisted structure and carbazole(Cz)with planar structure as donors,*** expected,two polymorphs(Crystal G and Crystal Y)of DBTDO-DMAC were obtained and exhibited distinct *** G originating from planar conformation exhibited mechanochromism(MC)phenomenon and the emission color changed from green to yellow with a redshift of 35 nm after ***,Crystal Y with folded conformation displayed obvious room-temperature phosphorescence(RTP)with yellow *** single crystal analyses,powder X-ray diffraction and theoretical calculation reveal that the different emissive behaviors are highly related to the molecular conformation and packing *** successful adjustment of molecular conformation provides some guidance in the design of other MC and/or RTP luminogens,broadens the molecule family with the tunable molecular conformation and opens up a new avenue for exploring possible adjustment of molecular packing in aggregates.

摘要：本文以经验论史学和质性研究作为理论视角,通过对中国早期电影史中谭鑫培出演《定军山》电影文献的梳理,尤其是收集和分析来源不同的“独立史料”,对“本片是否存在“”是否公映”进行研判。通过此案例,本文针对早期史料由于历史、社会、文化、日常经验等诸多原因造成的不准确不可靠现象,提出了对待电影文献的基本态度、论证方法及研究原则。

摘要：Developing materials with excellent properties has been the untiring pursuit of *** glasses(MGs)would be the ideal metallic materials if their size could be scaled up to be comparable to traditional *** address this challenge,a variety of approaches have been attempted over the past decades,including thermodynamicsbased alloy,3D printing and the recent artificial intelligenceguided optimal *** this study,a facile and flexible route was demonstrated to manufacture giant MGs(GMGs)with diameters more than 100 mm through the thermo-joining *** jointed GMG samples feature almost the same performance as the as-cast *** ability of manufacturing complex 3D components such as the Chinese Zodiacs was also *** approach might overcome the longstanding problem of glass forming ability(GFA)limitations in alloy systems and pave new concept and route to fabricate size unlimited MGs.

摘要：Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.

摘要：lithium-sulfur(li-S)batteries are regarded as one of the most promising next-generation energy storage systems due to their high theoretical energy density and low material ***,the conventional ether-based electrolytes of li-S batteries are extremely flammable and have high solubility of lithium polysulfides(liPS),resulting in a high safety risk and a poor life ***,we report an ether/carbonate co-solvent fluorinated electrolyte with a special solvation sheath of li^(+),which can prevent the formation of dissoluble long-chain liPS of the sulfur cathode,restrict li dendrite growth at the anode side,and show fire resistance in combustion *** a result,the proposed li-S batteries with 70 wt%sulfur content in its cathode deliver stable life cycle,low self-discharge ratio,and intrinsic ***,the unique passivation characteristics of the designed fluorinated electrolyte break several critical limitations of the traditional“liquid phase”-based li-S batteries,offering a facile and promising way to develop long-life and high-safety li-S batteries.

摘要：二阶非线性光学材料在激光技术中发挥着非常重要的作用,寻找综合性能优良的有机二阶非线性光学材料一直是材料和光学领域的前沿方向.目前的研究重点主要在于合成具有高二阶非线性光学效应和取向稳定性以及低光学损耗的非线性光学高分子材料,以更好满足高性能光学器件的制作要求.近几十年来,在多种分子模型及理论计算的支持下,科学家相继开发出许多行之有效的策略和方法,在这一领域取得了多方面重要的开拓性研究进展.本文首先介绍有机二阶非线性光学材料的核心构筑单元——生色团的设计与优化,阐述了共轭桥和电子给受体的结构对其微观二阶非线性光学性质的影响;然后结合“位分离”原理和“合适间隔基团”概念,总结了有效转换生色团的微观二阶非线性光学性质到材料宏观二阶非线性光学性能的策略和方法.在此基础上,围绕此类材料中存在的“非线性-稳定性”矛盾以及“非线性-透光性”矛盾探讨了综合性能优化的策略,从多角度归纳了分子设计的基本原则与改进方案以及分子聚集结构调控的有效途径.最后,针对该材料体系在实际应用中面临的关键挑战,对该领域未来的研究发展方向进行了讨论与展望.

摘要：核电机组中机械设备的振动会传递到与其相连的管路中,容易发生管路失效与气体泄露等事故,传统管路减振装置因管路布置复杂,存在安装困难和减振效果不理想等问题。针对上述情况,设计了一种结构简单且质量可调的二重动力吸振器(double dynamic vibration absorber,简称DDVA)。首先,根据机组管路实际参数对该动力吸振器进行参数设计,通过定点理论,以位移振幅比为参考对动力吸振器不断迭代优化,确定了DDVA的最优刚度与最优阻尼;其次,通过有限元仿真验证管路添加DDVA后的吸振效果,并与单个动力吸振器(single dynamic vibration absorber,简称SDVA)的吸振效果进行比对;最后,通过台架试验对DDVA吸振效果进行了试验验证。结果表明,DDVA将管路共振频率下的径向振动加速度降低了65%以上,吸振效果达到9 dB以上,这对于管路的吸振设计具有一定的工程指导意义。

摘要：室温磷光(RTP)材料因其独特的发光性质和在光电、传感、生物成像及信息加密等领域广阔的应用前景吸引了研究者的兴趣。近年来,科学家探索了各种方法调控有机分子的室温磷光,并通过磷光分子结构设计以及磷光保护基质的构建成功构筑了长寿命和高量子效率的有机室温磷光材料。超分子凝胶作为诱导室温磷光的新基质,具有三维网络结构、热可逆性质及刺激响应性等优势而引起关注。本综述围绕无金属室温磷光凝胶材料和含金属室温磷光凝胶材料,总结了近年来关于室温磷光凝胶材料的研究现状,并在此基础上,简要展望了室温磷光凝胶材料研究的发展趋势。