基于网格化管理视角下灾后应急物流决策模型与算法研究

灾害发生后,应急资源的需求预测与应急配送中心的合理选址是实现高效救援的关键。本文通过在网格化管理视角下的信息更新将应急救援过程划分为多个阶段,在开展救援的过程中实现救援信息收集和救援预测的同步开展,建立一种多阶段带时间约束的应急救援物资配送响应-时效性的选址模型。借助遗传算法(NSGA-II),实现了基于编码结构独立、路径相互关联基础上的多目标规划求解。本研究的决策模型及算法有着较好的搜索与寻优能力,对实际救援开展具有指导意义。     

Computer aided measurement of the electromagnetic parameter for the microwave absorbing materials

The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, the test data in requirement of traditional impedance method are "just enough" and not "redundant" to comprehensively evaluate the electromagnetic properties of materials. A novel optimization approach involving multiple impedance measurements is introduced in this paper to implement automatic measurement for electromagnetic parameters on microwave slot-line. Some results for standard samples and microwave absorbing materials are given.     

Approximating the zeros of analytic functions by the exclusion algorithm

We give a practical version of the exclusion algorithm for localizing the zeros of an analytic function and in particular of a polynomial in a compact of . We extend the real exclusion algorithm to a Jordan curve and give a method which excludes discs without any zero. The result of this algorithm is a set of discs arbitrarily small which contains the zeros of the analytic function.     

无人机三维路径规划的粒子群混合算法

路径规划是无人机控制过程中的重要环节之一,现有基于粒子群等算法的传统路径规划方法存在容易陷入局部最优等问题,无法适应现实场景中复杂环境及高搜索速度的要求。针对已有方法的缺陷,提出了一种无人机路径规划的高性能细菌觅食-遗传-粒子群混合算法,以传统粒子群优化算法为基础,引入细菌觅食算法及遗传算法思想,提高算法计算速度与能力,同时考虑实际场景中无人机的运行约束,进一步提高了方法的可用性。最后,利用仿真实验验证了所提方法的有效性,并通过与传统方法对比证明了所提方法在运行时间、规划航程等方面的优越性。     

基于双解码路径DD-UNet的脑肿瘤图像分割算法

针对医学图像中病灶区域尺度不一、边界模糊和周围组织强度不均匀所导致的分割精度降低问题,提出了一种基于双解码器的脑肿瘤图像分割模型。为了增强特征的表征力,提出了高阶微分残差模块并使用不同空洞率的扩张卷积用于提取特征编码,提高了网络模型的分割性能;引入上下文语义信息感知模块(multi scale dilation, MSD),从不同的目标尺度中提取更多的精细信息,提高了对结构细节信息的捕获能力,同时减少了编解码器之间的特征差异;在空间解码路径中使用选择性聚合空间注意力模块(spatial aggregation attention module, SAAM),增加了对有效空间特征的权重比例,减少了无效的特征干扰。在脑肿瘤数据集上进行了实验验证,实验结果表明,所提算法的Dice系数、平均交并比、敏感性、特异性、准确率等指标分别为：93.35%、90.71%、91.15%、99.94%、96.75%。     

基于改进3D UNet的前列腺MR图像分割

针对前列腺磁共振 (magnetic resonance, MR)图像边缘模糊、对比度较低,灰度值分布不均衡而导致分割精度较差的问题,提出了一种结合双路径注意力(dual path attention,DPA) 和多尺度特征聚合(multi-scale feature aggregation,MFA) 模块的改进3D UNet网络模型。首先,对数据集进行重采样和裁剪处理以适应模型输入。然后,在3D UNet网络的编码器各层引入DPA 并添加残差连接,加强特征的 编码能力。同时,在网络解码器中加入MFA模块,以充分利用空间上下文信息,增强语义信息。最后,在公开数据集PROMISE12上进行验证,所提出的模型的Dice系数为89.90%,Hausdorff 距离为9.37 mm。相比较于其他模型,所提出模型的分割结果更优,且参数量和运算量更少。     

Balancing MXene Surface Termination and Interlayer Spacing Enables Superior Microwave Absorption

Surface chemistry and interlayer engineering determines the electrical properties of 2D MXene. However, it remains challenging to regulate the surface and interfacial chemistry of MXene simultaneously. Herein, simultaneous modulation of Ti₃C₂T_x MXene surface termination and layer spacing by alkali treatment are achieved. The electrical and electromagnetic properties of Ti₃C₂T_x are investigated in detail with respect to KOH and ammonia concentration dependence. A high concentration of KOH caused the Ti₃C₂T_x layer spacing to expand to 13.7 Å and the surface O/F ratio to increase to 33.84. Because of its weaker ionization effect, ammonia provides finer tuning compared to the drastic intercalation of KOH with a thorough sweeping of the F-containing groups. Ti₃C₂T_x is enriched with conductive -OH termination after ammonia treatment, which achieves an effective balance with the increased interlayer resistance. Therefore, NH₃H₂O-Ti₃C₂T_x achieves broad-band impedance matching and exhibits an efficient microwave loss of −49.1 dB at a low thickness of 1.7 mm, with an effective frequency bandwidth of 3.9 GHz. The results herein optimize the electrical properties of Ti₃C₂T_x using surface and interfacial chemistry to achieve broad microwave absorption, providing a framework for enhancing the electromagnetic wave loss of intrinsic MXene.     

Halogenated Ti3C2 MXenes Prepared by Microwave Molten Salt for Hg0 Photo-Oxidation

Ti₃C₂ MXenes with different halogen modifications are prepared rapidly and efficiently by microwave molten salt method, and the MXene surface functional group modification is successfully achieved to address the problems of low purity, complex functional groups, and uncontrollable energy band structure of MXenes obtained by traditional liquid phase etching. Among them, the modification of the iodine (I) functional group onto the surface of Ti₃C₂ changes the energy band structure and band gap, resulting in easier photoexcitation and more photogenerated carriers. The increased Fermi energy is closer to the conduction band, the decreased surface work function weakens the electron confinement ability. The photogenerated carriers can migrate to the surface of the material more easily with extended lifetime, so the activity of the catalyst is improved. Further, for gaseous monomeric mercury (Hg⁰) photo-oxidative removal, Ti₃C₂-I₂ exhibits 85.5% efficiency of Hg⁰ photo-oxidative removal under visible light. Based on the experimental characterization and density functional theory calculations, a mechanism for the photo-oxidative removal of Hg° from Ti₃C₂-I₂ MXene is proposed, which provides a valuable strategy for studying Ti₃C₂ MXenes in the field of photocatalysis.     

面向电子战射频光传输的宽带射频信号杂散产生机理及优化方法

针对电子战系统的宽带射频信号波分复用传输,通过理论分析给出了微波光子链路中各关键参量对杂散信号的影响规律,提出了非均匀信道间隔分配的除杂优化方法。该方法通过微调各通道的波长,使四波混频产生的杂散频率超过电子战接收机带宽,从而降低杂散对系统的影响。该方案实现简单,且无需改变现有电子战系统架构,具有较好的工程实现性。实验结果表明:与等波长间隔相比,5通道非均匀波分复用信号传输1 km时,在接收机带宽内四波混频引起的杂散得到了显著优化,动态范围提升了26 dB以上。     

相位调制微波光传输链路特性分析（特邀）

常规的微波光子系统采用强度调制方式实现微波信号的电光转换,由于调制器采用马赫-曾德尔干涉结构(MZI),系统性能不仅受到自身正弦响应特性的制约,而且需要进行偏置点控制,因此存在动态范围受限、系统控制复杂以及3 dB固有损耗带来的效率不足的问题,而采用相位调制可避免该问题。围绕相位调制光传输链路,为了完成相位调制信号的光电解调,文章提出采用薄膜滤波器通过边带抑制与边带选通两种方式实现相位调制到强度调制的转换,并分析了链路射频性能与器件参数之间的映射关系。实测对比了相位调制与常规强度调制链路之间的传输特性,通过分析可知,在相同链路配置条件下,相位调制链路具有更高的传输效率,而且光滤波带来的均衡作用,使得相位调制链路的3 dB带宽比强度调制链路大两倍。