摘要：Fail-safe topology optimization is valuable for ensuring that optimized structures remain operable even under damaged *** selectively removing material stiffness in patches with a fixed shape,the complex phenomenon of local failure is modeled in fail-safe topology *** this work,we first conduct a comprehensive study to explore the impact of patch size,shape,and distribution on the robustness of fail-safe *** findings suggest that larger sizes and finer distribution of material patches can yield more robust fail-safe ***,a finer patch distribution can significantly increase computational costs,particularly for 3D *** keep computational efforts tractable,an efficient fail-safe topology optimization approach is established based on the framework of multi-resolution topology optimization(MTOP).Within the MTOP framework,the extended finite element method is introduced to establish a decoupling connection between the analysis mesh and the topology description *** examples demonstrate that the developed methodology is 2 times faster for 2D problems and over 25 times faster for 3D problems than traditional fail-safe topology optimization while maintaining similar levels of robustness.

摘要：一些鸟类的脖颈具有出色的柔性弯曲能力,模仿其特性可以设计仿生机器人.该类仿生设计的主要挑战是如何处理鸟类脖颈固有的灵活性和冗余的自由度.本文以鸡的脖颈结构为例,提出了一种模仿其脖颈结构特征的仿生超冗余机器人的设计方法.在我们的设计中,首先研究鸡脖颈的多骨节连接与运动特性,并定义了一个具有弹簧和万向节组合的仿生椎骨单元(BVU)来模拟鸡脖颈结构.然后,由三根钢丝平行驱动的三个仿生椎骨单元形成单个颈椎节段.最后,连接四个相同的颈椎节段构成了所提出的仿生超冗余机器人.结合几何分析法和Denavit-Hartemberg(D-H)参数法,研究了仿生超冗余机器人的驱动空间、关节空间和任务空间的运动学关系.通过蒙特卡洛方法进一步计算了可达工作空间.此外,原型样机的单平面运动实验的最大位置偏差约为四个颈椎节段总长度的5.8%.同时,一系列空间形状的展示,包括S形仿生弯曲配置和对兴趣目标体的成功缠绕和提升,证明了所提出的设计方法的有效性、机器人具有优异的灵活性和应用潜力.

摘要：Topological phases of matter have been extensively investigated in solid-state materials and classical wave systems with integer dimensions. However, topological states in non-integer dimensions remain almost unexplored. Fractals, being self-similar on different scales, are one of the intriguing complex geometries with non-integer dimensions. Here, we demonstrate fractal higher-order topological states with unprecedented emergent phenomena in a Sierpin? ski acoustic metamaterial. We uncover abundant topological edge and corner states in the acoustic metamaterial due to the fractal geometry. Interestingly,the numbers of the edge and corner states depend exponentially on the system size, and the leading exponent is the Hausdorff fractal dimension of the Sierpin? ski carpet. Furthermore, the results reveal the unconventional spectrum and rich wave patterns of the corner states with consistent simulations and experiments. This study thus unveils unconventional topological states in fractal geometry and may inspire future studies of topological phenomena in non-Euclidean geometries.

摘要：面向纤维复合材料与结构的优化设计需要,建立高效准确的纤维复材细观力学仿真工具具有重要意义.本文首次提出了包含内嵌纤维的三维计算晶粒(computational grains),用于纤维增强复合材料的直接细观力学建模,基于所开发的纤维计算晶粒方法,可以直接构造含有多根随机分布纤维的代表性体积单元(RVE).此外,本文提出了一种基于缩放柱调和函数的Papkovich-Neuber解来表征纤维和基体中独立的Trefftz试函数位移场,并且开发了一种新的多场边界变分原理来计算纤维计算晶粒的刚度矩阵.数值算例表明,对于内嵌大量随机分布纤维的RVE,纤维计算晶粒不需要构造复杂的网格,即可快速计算RVE的精确应力场,并预测其有效力学性能.此外,这也是内嵌纤维的三维有限元单元的首次提出.

摘要：To increase customers'satisfaction and promote product's competitiveness,a customized extended warranty(EW)policy is proposed,where the diversities in both the usage rate and purchase date are *** marginal approach is applied to describe the product's two-dimensional failure in terms of age and usage,***,minimal repair is adopted to restore the failure,and the virtual age method is applied to depict the effect of preventive maintenance(PM).On this basis,an optimization model is established to minimize the maintenance cost and warranty cost from the manufacturer's view,and multiple factors are taken into account,including the PM's intensity and its period,and EW's interval,etc.A numerical case study is provided to illustrate the effectiveness of the proposed *** results show that by considering the product's usage rate and the purchasing date of EW,the number of failures as well as the cost of maintenance and warranty can be reduced effectively.

摘要：The binding energy and generalized stacking-fault energy (GSFE) are two critical interface properties of two dimensional layered materials, and it is still unclear how neighboring layers affect the interface energy of adjacent layers. Here, we investigate the effect of neighboring layers by comparing the differences of binding energy and GSFE between trilayer heterostructures (graphene/graphene/graphene, graphene/graphene/boron nitride,boron nitride/graphene/boron nitride) and bilayer heterostructures (graphene/graphene,graphene/boron nitride) using density functional theory. The binding energy of the adjacent layers changes from -2.3% to 22.55% due to the effect of neighboring layer, with a very small change of the interlayer distance. Neighboring layers also make a change from -2% to 10% change the GSFE, depending on the property of the interface between adjacent layers. In addition, a new simple expression is proven to describe the GSFE landscape of graphene-like structure with high accuracy.

摘要：The influence of oxygen supply mode on the KIVCET (a Russian acronym for flash?cyclone?oxygen?electric?smelting) process was investigated using numerical simulation. The mass rate ratio (MRR) of central oxygen to lateral oxygen of the central jet distributor (CJD) burner was defined to express the oxygen supply mode, and the KIVCET process with an MRR ranging from 0.09 to 0.39 was simulated. The results show that there are four efficient reaction regions that correspond to four CJD burners. A higher central oxygen flow improves the mixing between particles and oxygen, thus enhancing reactions and shortening the reaction regions. However, a higher dust rate is induced due to the spread of the particle columns. The optimal MRR for a KIVCET furnace with a smelting capacity of 50000 kg/h is suggested to be 0.31. In this case, the chemical reactions associated with the feed are completed with an acceptable dust rate.

摘要：引语本文试图从产品服务系统的角度,探讨未来自动驾驶技术商业落地过程中的用户体验痛点,包括驾驶者注意力与活动的伴随自动驾驶技术升级而产生的变迁,和相应的设计考量因素。进而,我们提出了一个面向自动驾驶系统的交互设计空间,和相应的用户体验设计维度,试图为自动驾驶汽车交互设计和智能出行服务设计的新趋势提供行业思路借鉴。

摘要：多肽自组装形成的多孔结构是新一代多孔材料,在催化、传感、分离和药物递送等领域具有很好的应用前景.肽基多孔材料的孔内充满氨基酸侧链,因此可以通过合理设计或修改肽序列来调节其孔径大小和性能.功能基团和金属离子的引入进一步扩展了多肽基多孔材料的结构与性能.在这篇综述中,我们讨论了肽基多孔材料的设计、合成、组装及其性能,并综述了近年来其在不同领域的应用.

摘要：自20世纪60年代后现代主义盛行以来,每一次巨大的社会变革都导致了博物馆模型的重新探索和创新实验。在中国,博物馆在文化机构中扮演着至关重要的角色,博物馆的固化与社会流动性存在着根本的冲突。然而,从知识传播到文化生产,中国的博物馆已经做出了许多积极的尝试,以线上和线下的形式拓展博物馆的边界和功能。固定的和有形的博物馆变成了流动的和无形的博物馆,像到处流动的水。