摘要：本文提出了一种考虑几何非线性的三维连续体结构显式拓扑优化方法.采用移动可变形孔洞(MMV)方法描述结构,具有设计变量少、可与CAD系统无缝集成的优点.此外,由于结构拓扑描述模型与有限元分析模型之间解耦,在有限元分析中可以直接删除孔洞区域的冗余自由度,从根本上解决有限变形拓扑优化因弱单元引起的收敛性问题,同时显著提高了有限元分析的计算效率.数值算例验证了该方法的有效性,结果表明:(1)无论单工况还是多工况载荷作用下,几何非线性对三维结构的最优拓扑构型均具有显著影响;(2)优化后的几何非线性结构可以充分利用大位移和小应变来降低结构柔顺度;(3)几何非线性拓扑优化应评估优化设计的临界失稳荷载,以保证结构服役的安全性.

摘要：模拟和研究了高性能同心金属-绝缘体-金属环的光学特性.通过改变内环折射率ni,内环和外环之间的共振波长和耦合强度可以被大范围调谐,内环和外环的能量分配比也可以被调节.当能量主要分布在内环时,可以有效地抑制损失到波导的能量,从而得到该结构的超高品质(Q)因子.当外环能量较大时,同心双MIM环与波导之间的耦合强度较大,得到该结构的消光比高.提出的同心双MIM环为设计先进的等离子体谐振腔提供了新的视角.

摘要：Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline *** we report a facile strategy for designing Ni2W4C-W3C Janus structures with abundant Ni-W metallic bonds on surfaces through interfacial *** Ni atoms into the W3C crystals in reaction progress generates a new Ni2 W4C phase,making the inert W atoms in W3C be active sites in Ni2W4C for overall water *** Ni2W4CW3C/carbon nanofibers(Ni2 W4-W3C/CNFs)require overpotentials of 63 mV to reach 10 mA cm^-2 for hydrogen evolution reaction(HER)and 270 mV to reach 30 mA cm^-2 for oxygen evolution reaction(OER)in alkaline electrolyte,*** utilized as both cathode and anode in alkaline solution for overall water splitting,cell voltages of 1.55 and 1.87 V are needed to reach 10 and 100 mA cm^-2,*** functional theory(DFT)results indicate that the strong interactions between Ni and W increase the local electronic states of W *** Ni2W4C provides active sites for cleaving H-OH bonds,and the W3C facilitates the combination of Hads intermediates into H2 *** in situ electrochemical-Raman results demonstrate that the strong absorption ability for hydroxyl and water molecules and further demonstrate that W atoms are the real active sites.

摘要：大力推进材料和装备的轻量化、减量化是实现节能减排、加快建设节约型社会的关键措施,是新世纪工程科技的发展方向。大至海洋平台、大飞机机身和动车组车体,再到日常生活中的车辆,乃至小电子散热器件等,轻量化和多功能化均成为其发展中重要一环。围绕相关特殊工况应用条件下的轻质材料与结构的设计和研究面临一系列挑战:质量轻、力学强度高、散热性能好、动力学性能和隔振、隔声性能可调等多功能要求,因此如何在现有的材料和结构基础上进一步减轻重量并获得更优良的综合性能是材料科学、固体力学、传热、声学、优化设计等诸多领域工作者面临的共同挑战。基于本课题组近5年来围绕"超轻多孔结构创新构型的多功能化基础研究"国家基础研究计划项目所开展的一系列工作,综述了国内超轻多孔材料与结构最新发展水平的研究成果,总结了具有特定或多功能化应用的这类新型轻质多孔材料多学科交叉研究的进展,包括材料制备,力学、热学和声学特性,以及无损检测及优化设计等。

摘要：Effective separation of photogenerated carriers plays a vital role in governing the efficiency of photo-electrocatalytic ***,the advancement in enhancing the intrinsic carrier separation efficiency of semiconductors has shown limited ***,we reported the use of a magnetic field to improve the photoelectrochemical water splitting of a magnetic Co_(3)O_(4)/TiO_(2)photoanode by boosting the photogenerated carrier separation *** the presence of the magnetic field,oxygen evolution reaction occurs with a high photocurrent density of 0.86 mA cm^(−2)at 1.23 V versus VRHE,and an applied bias photon-to-current efficiency of 0.342%at 0.61 ***,the photoanode maintains its oxygen evolution reaction for more than 400 h with photocurrent decays by ca.10%.Observations made in this effort show that the enhancement of photo-electrocatalytic efficiency by a magnetic field is a consequence of the effect of the Lorentz force generated by the magnetic field on photogenerated carriers and ions near the Co_(3)O_(4)/TiO_(2)photoanode,which improves the carrier separation efficiency and the bubble release *** results suggest that manipulating photoelectrode carriers by using a magnetic field is a promising strategy to design high-performance photoelectrochemical for water splitting.

摘要：Herein,a novel photonic coordination polymer material was constructed by aggregation-induced emission luminogen(AIEgen)containing a tripyridyl moiety used as the linking *** displayed a spontaneous direct centrosymmetric to noncentrosymmetric phase transition in a single *** two crystals,before and after the phase transition,were both controllably synthesized and characterized by single-crystal X-ray *** being exposed to air,the centrosymmetric metastable phase(1-α)transitioned to a new stable phase with a noncentrosymmetric structure(1-β).Interestingly,the 1-βstructure exhibited a strong phasematching second-harmonic generation(SHG)response,about4.5 times higher than that of KH2PO4(KDP).In order to better understand the relationship between the structure and the nonlinear optical properties,the dipole moments were calculated and ***,the noncentrosymmetric phase with high thermal stability for 1-βretained and improved the initial photoluminescent properties of the AIEgen ligand after the structural phase transition from 1-α,and simultaneously produced the excellent SHG property,which are beneficial for the design and construction of excellent optical materials.

摘要：Geopolymer is produced through the polymerization of active aluminosilicate material with an alkaline activator,leading to the formation of a green,inorganic polymer *** concrete(GPC)has become a promising low-carbon alternative to traditional Portland cement-based concrete(OPC).GPC-bonded reinforcing bars offer a promising alternative for concrete structures,boasting excellent geopolymer binder/reinforcement bonding and superior corrosion and high-temperature resistance compared to Portland ***,due to differences in the production process of GPC,there are distinct engineering property variations,including bonding *** literature review provides an examination of the manufacturing procedures of GPC,encompassing source materials,mix design,curing regimes,and other factors directly influencing concrete ***,it delves into the bond mechanism,bond tests,and corresponding results that represent the bond *** main conclusions are that GPC generally has superior mechanical properties and bond performance compared to ordinary Portland cement concrete(OPC).However,proper standardization is needed for its production and performance tests to limit the contradictory results in the lab and on site.

摘要：We present a design method for calculating and optimizing sound absorption coefficient of multi-layered porous fibrous metals （PFM） in the low frequency range. PFM is simplified as an equivalent idealized sheet with all metallic fibers aligned in one direction and distributed in periodic hexagonal patterns. We use a phenomenological model in the literature to investigate the effects of pore geometrical parameters （fiber diameter and gap） on sound absorption performance. The sound absorption coefficient of multi- layered PFMs is calculated using impedance translation theorem, To demonstrate the validity of the present model, we compare the predicted results with the experimental data. With the average sound absorption （low frequency range） as the objective function and the fiber gaps as the design variables, an optimization method for multi-layered fibrous metals is proposed. A new fibrous layout with given porosity of multi-layered fibrous metals is suggested to achieve optimal low frequency sound absorption. The sound absorption coefficient of the optimal multi-layered fibrous metal is higher than the single- layered fibrous metal, and a significant effect of the fibrous material on sound absorption is found due to the surface Dorosity of the multi-layered fibrous.

摘要：薄膜体声波谐振器(FBAR)力传感器作为一种新型的谐振式传感器,力敏特性是其设计原理。以FBAR微加速度计为例研究了工作在纵波模式,采用具有纤锌矿结构的AlN作为压电薄膜的FBAR,施加应力载荷后,其弹性常数改变导致FBAR谐振频率偏移的力敏特性。首先,采用有限元(FEA)静力学仿真,得到惯性力载荷作用下集成在硅微悬臂梁上的压电薄膜的应力分布;选取最大应力值作为载荷,基于第一性原理计算纤锌矿AlN的弹性系数与应力的关系式,预测惯性力载荷作用下AlN弹性系数的最大变化量。其次,采用谐响应分析,对比空载和不同惯性力载荷作用下FBAR微加速度计的谐振频率和偏移特性,预测FBAR微加速度计的加速度-谐振频率偏移特性。最后仿真分析得到:惯性力载荷作用下,FBAR微加速度计的谐振频率向高频偏移,灵敏度约为数kHz/g;其加速度增量-谐振频率偏移特性曲线具有良好的线性度。