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：Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft unsteady aerodynamic design and flight dynamics *** this paper,aiming at the problems of poor generalization of traditional aerodynamic models and intelligent models,an intelligent aerodynamic modeling method based on gated neural units is *** time memory characteristics of the gated neural unit is fully utilized,thus the nonlinear flow field characterization ability of the learning and training process is enhanced,and the generalization ability of the whole prediction model is *** prediction and verification of the model are carried out under the maneuvering flight condition of NACA0015 *** results show that the model has good *** the interpolation prediction,the maximum prediction error of the lift and drag coefficients and the moment coefficient does not exceed 10%,which can basically represent the variation characteristics of the entire flow *** the construction of extrapolation models,the training model based on the strong nonlinear data has good accuracy for weak nonlinear ***,the error is larger,even exceeding 20%,which indicates that the extrapolation and generalization capabilities need to be further optimized by integrating physical *** with the conventional state space equation model,the proposed method can improve the extrapolation accuracy and efficiency by 78%and 60%,respectively,which demonstrates the applied potential of this method in aerodynamic modeling.

摘要：多硫离子穿梭和锂枝晶生长严重阻碍了锂硫电池的实际应用进程,而合理的隔膜结构可以达到一石二鸟的作用.本工作设计了一种携带有分散性TiN/CoO颗粒的氮掺杂碳纳米管结构(TCCNT),并将其用于锂硫电池隔膜修饰层.TCCNT的多孔结构和表面/内部携带的TiN/CoO颗粒不但实现了对多硫化物的物理、化学吸附和快速催化转化作用,其高导电性的空腔结构和亲锂作用还能够均化锂离子流,在5 mA cm^(-2)的电流密度下实现长达2000 h的均匀锂沉积/剥离过程.TCCNT合理的结构设计有利于各材料组分之间最大限度地发挥协同效应.采用改性隔膜所组装的锂硫电池在常规和高硫载量两种情况下均表现出较好的电化学性能,表明其具有一定的实际应用潜力.

摘要：柔性可穿戴的紫外线探测器在个体紫外线暴露监测、智能仿生眼和军事领域受到广泛关注.然而,传统不可拉伸的材料和器件结构设计限制了设备在可动态变形的人体皮肤和非平面表面上的精确监测应用和稳定附着.在本研究中,我们提出了基于氧化铜/碳-水凝胶-氧化锌/碳的新型应变隔离异质结构的本征可拉伸(拉伸应变或弯曲高达150%)紫外线探测器,该探测器具有高灵敏度(开/关比为2100%)、高稳定性(大于4000次循环),以及快速响应和恢复时间(分别为1.5和4 s).值得注意的是,该探测器通过水凝胶桥在氧化铜/碳和氧化锌/碳电极之间引入的p-n结能带结构,以及离子导电水凝胶中I^(-)/I_(3)^(-)的电化学反应机制,显著提高了其载流子效率和紫外线响应强度.本文通过集成传感器与所设计的电路板,进一步开发了一种无线紫外线报警系统,用于紫外线强度超标警报.此外,本文还设计了一种光电传感器阵列,并将其用作视网膜假体,以实现对环境紫外线强度的实时监测和成像.本文基于水凝胶基异质结构为开发可穿戴、可拉伸的光电紫外线传感器单元和成像阵列提供了一种新的可行方法.

摘要：金属材料经常暴露在高应变率和复杂的应力条件下.研究这些材料的动态力学行为对工程设计和工业应用至关重要.本文研究了TC17钛合金在压缩/拉伸-扭转作用下的动态塑性流动行为.研究了TC17钛合金在准静态和动态载荷下的初始屈服行为,并采用杨、郭和李提出的动态不对称屈服准则(DAYC)来表征动态初始屈服行为.根据不同应力状态下的硬化特性,提出了一种修正的动态硬化规律(MDHL)来拟合加载面.研究了TC17钛合金在准静态和动态载荷作用下的塑性流动方向.结果表明,塑性势函数基本符合相关联流动法则.总之,本文系统性的研究了TC17钛合金的屈服性能,应变硬化规律和塑性流动规律,并利用DAYC和MDHL对其进行了表征.

摘要：At present,metal-organic framework(MOF)-derived nano-micro architectures are actively explored for electromagnetic(EM)wave absorption owing to their flexible composition and structural manipulation that enhance dielectric and magnetic ***,the basic design principles in MOF-derived microwave absorption materials have not been *** review is devoted to analyzing design principles in MOF-derived microwave absorption materials from the following perspectives:diverse monomers(ligands and ions of MOFs),topologies,chemical states,and physical *** derived essential information regarding the EM wave absorption mechanism and the structural-functional dependency is also comprehensively ***,a clear insight into the challenges and perspectives of the industrial revolution upgrading in this promising field is proposed.

摘要：In topology optimization of structures considering flexibility, degenerated optimal solutions, such as hinges, gray areas and disconnected structures may appear. In this paper, built upon the newly developed morphable component based topology optimization approach, a novel representation using connected morphable components(CMC) and a linkage scheme are proposed to prevent degenerating designs and to ensure structure integrity. A lower bound condition of the thickness of each component is also incorporated to completely remove the smallest components in an optimal configuration. Designs of flexible structures, such as compliant mechanism design, maximum compliance structure design, and design of low-frequency resonating micro devices are studied to validate the proposed methodology. Our work demonstrates that the new methodology can successfully prevent degeneration solutions and possesses other advantages, such as minimum member size control in topology optimization of flexible structures.

摘要：柔性梁结构是水下航行器的常见部件,其模态振动传递会损害部件服役寿命和系统工作精度。常见的抑制梁振动的方法有吸振、阻尼和主动控制等。控制的难点在于低频抑振和拓宽有效抑制频带。而常见的抑振方法的应用需要获取准确的结构参数和激励参数,对于非完备参数条件系统的适用性不足。本文基于时变边界结构的能量传递特性,提出了一种针对模态振动抑制的时变边界方法。该方法可同时抑制多阶共振,而不必针对每阶振动特性进行额外设计。首先,建立时变边界梁的动力学模型,采用时域分段解析法计算时变边界梁的瞬态振动,并与有限元法的结果进行对比验证了该方法的正确性。然后,通过时变边界梁和固定边界梁的结果对比验证了时变边界方法对共振的抑制效果。最后,分析初始条件、阻尼、时变范围和时变频率等参数对时变边界方法抑振效果的影响,发现阻尼可消耗由模态振动分散至其他频域的能量,时变边界所对应的谐振频率变化范围越大时,对共振峰值的抑振性能越好,并由此得到了时变位置优化区域。

摘要：This study proposed a design and optimization strategy for a tandem arranged cascade using the Non-dominated Sorting Genetic Algorithm(NSGA) Ⅱ multi-objective optimization algorithm and Back Propagation(BP) neural network technology. The NASA Stage 35 was employed as the initial bench mark in the present study and five geometric control parameters were working as the optimization parameters aiming to enhance the aerodynamic performance in terms of total pressure rise and efficiency. Results showed that the feasibility and capability of the proposed optimization strategy was successfully examined. In view of the fact that the initial tandem cascade(directly scaling down from NASA Stage 35) cannot guarantee the aerodynamic performance, first optimization trial was conducted to optimize the initial design. Results showed that the optimum can improve the flow quality whereas the separation on the blade is decayed or even eliminated particularly at the tip and root regions. However, compared with the initial tandem design, the enhancement in total pressure ratio(0.47%) and efficiency(1%) are too small to be noticed. Second investigation was particularly emphasizing on a high turning tandem compressor with an increment by 28°. The pressure rise and efficiency were augmented by 1.44% and 2.34%(compared to the initial tandem design), respectively. An important conclusion can be drawn that the optimization strategy is worthy to be used in high turning compressors with a considerable performance improvement.

摘要：To avoid the high computational cost and much modification in the process of applying traditional reliability-based design optimization method, a new reliability-based concurrent subspace optimization approach is proposed based on the comparison and analysis of the existing multidisciplinary optimization techniques and reliability assessment methods. It is shown through a canard configuration optimization for a three-surface transport that the proposed method is computationally efficient and practical with the least modification to the current deterministic optimization process.