摘要：Mg-Al alloys have excellent strength and ductility but relatively low thermal conductivity due to Al *** accurate prediction of thermal conductivity is a prerequisite for designing Mg-Al alloys with high thermal ***,databases for predicting temperature-and composition-dependent thermal conductivities must be *** this study,Mg-Al-La alloys with different contents of Al2La,Al3La,and Al11La3phases and solid solubility of Al in the α-Mg phase were *** influence of the second phase(s) and Al solid solubility on thermal conductivity was *** results revealed a second phase transformation from Al_(2)La to Al_(3)La and further to Al_(11)La_(3)with the increasing Al content at a constant La *** degree of the negative effect of the second phase(s) on thermal diffusivity followed the sequence of Al2La>Al3La>Al_(11)La_(3).Compared with the second phase,an increase in the solid solubility of Al in α-Mg remarkably reduced the thermal *** the basis of the experimental data,a database of the reciprocal thermal diffusivity of the Mg-Al-La system was established by calculation of the phase diagram (CALPHAD)*** a standard error of±1.2 W/(m·K),the predicted results were in good agreement with the experimental *** established database can be used to design Mg-Al alloys with high thermal conductivity and provide valuable guidance for expanding their application prospects.

摘要：The slow light propagation in a line waveguide in the two-dimensional triangular photonic crystal has been numerically studied, based on which a wideband photonic crystal waveguide with low group-velocity and low dispersion is proposed. The numerical simulation analysis shows that it is possible to maximize the group index and minimize the group-velocity dispersion in wide bandwidth by increasing the radius of the basic air hole and changing the position of the first two rows of air holes in photonic crystal waveguides. Such a photonic crystal waveguide exhibits low group velocity and low group-velocity dispersion over a broad wavelength range. A larger group index-bandwidth product is achieved in this type of waveguide structure. The numerically computed results present the normalized bandwidth as 0.32%, 0.48% and 0.642% corresponding to the group index of 85, 58 and 45, respectively.

摘要：薄壁结构是机械设计中常用的结构形式,其柔性动力学问题一直是工程研究的前沿。针对具有薄壁结构特性的弹药机械臂,发展了一种基于板壳理论的弹药机械臂柔性多体动力学建模方法.我们在浮动参考坐标框架下,得到了Reissner-Mindlin壳结构的运动学方程,其中结构膜变形和弯曲变形与刚性运动的耦合,这是区别于实体结构的特点。为了克服壳体单元模拟中的膜锁定和剪切锁定问题,引入一种基于边中心的应变平滑DSG(ECSS-DSG)单元对结构离散.该方法可以获得更好的膜变形和弯曲变形行为,并且有效克服剪切自锁问题,在结构模态分析中表现出更好的效果.在此基础上,结合实验对弹药机械臂模型参数进行了辨识,并且对辨识模型在各种工况下的动态响应进行了验证,证明了本文方法具有良好的鲁棒性.本文的工作不仅可以为弹药机械臂的进一步研究提供理论支撑,而且可以为薄壁结构多体系统的动力学研究提供参考.

摘要：本文介绍了一种通过调整卡箍使得管道避免发生共振的设计策略.当管道的固有频率在机械设备运作时产生的振动频率范围内,会引发共振现象,给机械设备的正常操作带来严重的灾难.因此,把机械设备操作产生的振动频率范围定义为频带禁区.通常,工程中的管道被简化为多跨输流管道:通过将卡箍简化为线性和扭转刚度,建立了多跨输流管道的整体管道模型.通过采用Galerkin截断方法并应用广义特征值方法,获得了多跨输流管道的固有频率.通过对比不同长度的管道固有频率和频带禁区,定义了管长的安全范围和共振范围分别为频带禁区的外和内,并且通过分析卡箍的影响推导得出了绝对安全长度和绝对共振长度.此外,还确定了卡箍刚度和位置对安全范围的影响.结果表明,通过调整卡箍的线性刚度、扭转刚度和位置,管道的安全范围会发生显著地变化.根据这些结果,提出了一种管道设计策略,从而避免了管道的共振发生,并减少了使用卡箍的数量.最后,以飞机上的一段管道为例进行了设计,结果表明:通过调整卡箍,管道的固有频率成功地远离了频带禁区,因而在飞机的运行过程中不会发生共振.总而言之,通过调整卡箍的刚度或位置,可以获得避免多跨输流管道发生共振的设计策略.

摘要：As one of the Four Great Masterpieces of China,The Romance of the Three Kingdoms has become a landmark of ancient Chinese literature with vivid and profound character images,ups and downs of politics and war descriptions,and appealing historical *** being introduced to Japan in the second half of the 17th century,it was spread in Japanese society and was accepted for literary value,social needs and other reasons,then a series of evolutions were produced by combining with local culture,eventually becoming a national culture in *** paper selects the most popular text of The Romance of the Three Kingdoms with 24 chapters and 120 verses in the Wanli period of the Ming Dynasty,and the Japanese translation of The Popular Romance of the Three Kingdoms published by Hunan Wenshan in 1689 as the objects,guided by Ralph Linton’s“Manifestation,Selection,Integration”cultural communication research method,to analyze the dissemination,acceptance and evolution of The Romance of the Three Kingdoms in 17-20 centuries’Japan,which started from the field of literature,then combined with various cultural forms and spread to the civic class,and finally entered politics area and produced a series of evolutions under the influence of Japanese values to become the representative culture of *** paper suggests that in today’s world of frequent cultural exchanges,China should,based on strengthening cultural self-confidence,actively and appropriately select and accept foreign cultures with the attitude of prioritizing our own culture and utilizing foreign culture for our own *** research outcome can provide experience for the current Chinese culture to go to the world with high quality.

摘要：Let (v,u × c,λ)-splitting BIBD denote a (v,u × c,λ)-splitting balanced incomplete block design of order v with block size u × c and index λ. The necessary conditions for the existence of a (v,u × c,λ)-splitting BIBD are v uc, λ(v-1) ≡ 0 0 mod (c(u-1)) and λv(v-1) ≡ 0 mod (c2u(u-1)). In this paper, for 2 λ 9 the necessary conditions for the existence of a (v,3 × 3,λ)-splitting BIBD are also suffcient with one possible exception for (v,λ) = (39,9).

摘要：Aerodynamic performance of low-Reynolds-number high-lift airfoil makes a great impact on designing a high-efficiency propeller for low-dynamic vehicles in stratosphere. At high altitude,low-Reynolds-number airfoils are supposed to have high lift-drag ratio or high endurance factor at cruising attack angle along with good stall characteristics. To design such a high-performance low-Reynolds-number high-lift airfoil,the paper established a hierarchical multi-objective optimization platform by combing direct search optimization algorithm EXTREM and airfoil flow field solver XFOIL to automatically and quickly calculate aerodynamic performance function of airfoil by computer. It provides an effective solution to multi-point design problem of low-speed low-Reynolds-number airfoil. It can be seen from the results of three typical optimization examples,the new airfoil E387_OPT2,FX63-137_OPT2 and S1223_OPT2 based on hot low-Reynolds-number high-lift airfoils (Eppler 387 airfoil,Wortmann FX63-137 airfoil and S1223 airfoil) can meet the optimization design requirements and have very good aerodynamic characteristics in both design state and non-design state. Thus,the applicability and effectiveness of hierarchical multi-objective optimization platform are verified.

摘要：高通量计算与材料数据库推动了数据驱动的机器学习方法的发展.机器学习已经成为材料计算研究的重要方法,在分析材料数据、加速材料计算、预测材料性质、推进新材料发现、筛选和设计等方面展现出极大的潜力.众多与材料计算相交叉的机器学习方法、模型以及框架不断涌现.本文综述了近年来光电半导体材料计算设计领域内机器学习方法的最新进展与应用.介绍了机器学习的流程与类型,基于不同材料表示方法的浅层模型、集成模型和深度神经网络,以及相关材料数据库和相关工具.我们还讨论了这些模型在预测材料稳定性与光电性质、材料逆向设计、构建材料构效关系等方面的应用.最后,本文对目前机器学习方法存在的机遇与挑战,即数据数量与质量、材料的表示、材料逆向设计做了进一步总结与讨论.

摘要：昆虫和微型飞行器存在间隙狭窄的串列式拍动翼-固定翼构型.与独立的拍动翼相比,两翼之间的干扰作用可以增强推力,但推力增量能否通过倾斜拍动平面而转化为升力尚不清楚.本文采用浸润边界法和格子玻尔兹曼方法研究了这种串列双翼构型在不同拍动平面倾角下的气动性能。结果表明,当拍动平面倾角为75°时,干扰作用产生的大部分推力增量转化为升力增量,证明了通过倾斜拍动平面实现升推转化的可行性。除了几何投影和有效迎角改变的贡献外,升力增量还来自于两翼位置最接近时的额外升力峰,其流动机制包括两部分:一方面,固定翼阻碍了拍动翼产生的射流并在间隙内产生了较强的水平回流,从而增强了拍动翼上翼面后缘附近的低压区;另一方面,固定翼前方的上洗气流增强了拍动翼下翼面的高压区.进一步分析表明,这种增升机制在多个拍动幅度下有效,因此可以认为该机制在三维构型中仍然存在。上述研究结果揭示了一种通过倾斜拍动平面来增强串列式拍动翼-固定翼构型升力的新机制,为以这种构型为基础的微型飞行器提供了新设计方案.

摘要：具有生物力学和生化活性的敷料在伤口护理和皮肤组织再生中起着至关重要的作用.然而,机械失配和药物释放管理所涉及的问题限制了当前敷料的有效使用.在本工作中,我们报道了一种简单的策略,即采用聚偏二氟乙烯(PVDF)作为底物,通过嵌入不同尺寸的沸石咪唑酸盐框架(ZIF-8)种子,以推动具有均匀蜂窝结构的高柔性金属有机框架(MOF)复合膜的受控生长,用于药物负载和释放.以嵌入的种子为控制中心,形成的多孔膜具有约0.7-3μm的宽孔隙.这种可调节的微尺度孔与ZIF-8中的固有纳米孔不仅可以有效地提高抗炎类药物的负载(姜黄素,CCM),而且还能够快速并可控地释放药物,大大提高了抗菌活性,同时促进细胞生长.其中,在40 nm种子上生长的0.7μm多孔膜的表现优于其他蜂窝膜,与2μm多孔膜(相当于裸PVDF基质)相比,细胞增殖能力提高了约2倍,针对金黄色葡萄球菌(***)和大肠杆菌(***)的抗菌活性分别提高了5倍和2.4倍,是基底抗菌活性的5倍,这是因为这种最佳孔几何结构具有CCM和Zn2+释放特性的平衡效应.这种可控分层孔阵列膜的独特性质有望真正用于伤口愈合,同时也为生物医学设计提供了新的指导.