摘要：Researchers have been attempting to characterize heterogeneous catalysts in situ in addition to correlating their structures with their activity and selectivity in spite of many ***,we review recent experimental and theoretical advances regarding alkyne selective hydrogenation by Pd‐based catalysts,which are an important petrochemical *** catalytic selectivity for the reaction of alkynes to alkenes is influenced by the composition and structure of the *** progress achieved through experimental studies and atomic simulations has provided useful insights into the origins of the *** important role of the subsurface species(H and C)was revealed by monitoring the catalyst surface and the related catalytic *** atomic structures of the Pd catalytic centers and their relationship with selectivity were established through atomic *** combined knowledge gained from experimental and theoretical studies provides a fundamental understanding of catalytic mechanisms and reveals a path toward improved catalyst design.

摘要：LASP(large-scale atomistic simulation with neural network potential)software developed by our group since 2018 is a powerful platform(***)for performing atomic simulation of complex *** software integrates the neural network(NN)potential technique with the global potential energy surface exploration method,and thus can be utilized widely for structure prediction and reaction mechanism *** we introduce our recent update on the LASP program version 3.0,focusing on the new functionalities including the advanced neuralnetwork training based on the multi-network framework,the newly-introduced S^(7) and S^(8) power type structure descriptor(PTSD).These new functionalities are designed to further improve the accuracy of potentials and accelerate the neural network training for multipleelement *** Cu-C-H-O neural network potential and a heterogeneous catalytic model as the example,we show that these new functionalities can accelerate the training of multi-element neural network potential by using the existing single-network potential as the *** obtained double-network potential Cu CHO is robust in simulation and the introduction of S^(7) and S^(8) PTSDs can reduce the root-mean-square errors of energy by a factor of two.

摘要：Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump *** paper proposes a novel TPG-based hypersonic bump inlet design *** method consists of two ***,a parametric optimization approach is employed to design a series of 2D inlets with various compression ***,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump *** method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric *** performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/*** show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure *** addition,the starting ability is significantly improved by adding the bump *** reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted ***,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow *** results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.

摘要：电磁散射数据是目标识别研究的基础,但由于试验测量成本高、可重复性差等问题,空中目标电磁散射实测数据十分有限。基于去遮挡的N点模型和电磁计算数据插值研究了空中目标动态电磁散射数据仿真方法,设计了空中目标动态电磁数据仿真系统,该系统将电磁散射仿真与实际飞行场景相结合,支持场景自定义和空中目标三维模型库扩展。分析了飞机和巡航导弹2类目标仿真数据及成像结果,结果验证了仿真方法正确性和系统有效性,可为研究实际场景下的空中目标识别提供支撑。

摘要：针对微波光子系统对片上高速调制器件的使用需求,基于铌酸锂材料的线性电光效应,研究通过开展片上器件的光电联合仿真设计,利用与CMOS工艺相兼容的半导体器件制备方法,将低损耗铌酸锂波导、高效耦合模斑转换器、高频微波信号传输线等片上光电器件集成在绝缘体上的铌酸锂(LNOI)晶圆上,实现调制器芯片的片上集成化;采用微光学耦合工艺实现芯片实现光纤阵列的光信号输入输出;采用引线键合方式实现芯片-薄膜电阻-射频接头的阻抗匹配和电信号低损传输;最后采用平行封焊完成芯片-光纤-管壳的气密性封装,以提高调制器的可靠性和环境适应性。测试得到器件光功率插损15 G(@3 dB),动态半波电压<6 V(@10 GHz),满足光电振荡器等相关微波光子器件的应用需求。

摘要：动力学分析是运动装置设计过程中一项重要的内容。针对六自由度磁悬浮运动台,建立了基于牛顿力学的运动微分方程,分析了带有允余自由度的位置测量和计算方法、六自由度解耦多轴闭环反馈控制方法。基于Simulink软件,利用Simscape(物理模型)中的Multibody模块搭建了运动台的动力学模型和测量系统模型,通过控制模块建立了运动台的控制系统模型,将两者结合起来组成了能够按照设定轨迹运动的动力学仿真模型。为运动台设置加速度为2.4g的96场曝光轨迹,仿真得到运动台的各个电机在各个方向上的出力。该仿真模型搭建过程为多自由度运动装置的动力学分析提供参考。

摘要：近年来,基于机器学习的大规模原子模拟技术的发展为许多化学分支的发展带来了巨大的希望。这些模拟具有高速度和高精度的特点。本文概述了基于机器学习势函数的原子模拟的3个关键方面的最新进展,即机器学习模型和结构描述子的开发,全局势能面训练集的生成,以及基于主动学习的势函数自动训练。研究表明,最近设计的指数型结构描述子和前馈神经网络模型非常适合生成高度复杂的全局势能面。通过神经网络势函数在材料和反应模拟中的2个最新应用来说明基于机器学习势函数的原子模拟如何有助于发现新材料和反应。

摘要：该文提出了基于无源介质谐振器腔内磁偶极子谐振的准超方向性再辐射,旨在增强薄导电板受到平面电磁波侧向照射时的后向散射截面。在平面电磁波激励下,设计适当的长方介质体中可诱导产生具有磁偶极子再辐射特征的混合电磁谐振模式。以长方介质体为基本谐振单元,将两个相同的介质体沿入射波传播方向紧密级联以组成一个超单元。超单元的两个介质体中的磁场强度与电场强度矢量均呈现相反的方向且相近的幅度,接近等幅而反相的内部场分布使超单元类似一个二元准超方向性磁偶极子阵列,由此产生的准超方向性再辐射有效地贡献于后向散射截面增强。进一步,由镜像原理,将超单元剖面厚度减半并加载于薄导电板表面。结果表明,剖面厚度仅为0.078λ0的介质谐振器形成基于磁偶极子的准超方向性再辐射,在谐振频率处可显著修改薄导电板的侧向回射特性,进而在相对宽带宽角范围内对侧向入射波实现有效的后向散射截面增强。

摘要：快速高效的船舶水动力计算方法可显著缩短船型优化设计周期,但船舶剖面形状复杂,采用刘易斯剖面法和田才图谱法等均难以实现剖面准确定义,制约了水动力系数预报精度。该文结合先验知识与自动编码器模型提出了一种新的船体剖面参数化方法,在此基础上通过神经网络以数据驱动方式建立了剖面参数化特征和频率与二维无限水深水动力系数之间的映射关系,实现了附加质量和阻尼系数的准确高效预报。经仿真验证,提出的神经网络模型预测结果与切片理论计算结果吻合良好,预测精度较高,有助于船舶设计与优化工作。

摘要：本文提出了一个超薄的4-bit双极化编码超表面,通过正交线极化波的独立操控来实现双模式涡旋波束的生成.提出的超表面从顶至下依次由“H”形的金属贴片、介质基板层和金属接地层组成.为了证明所提出的概念,设计并制造了一个编码超表面.制造的编码超表面,在正交线极化波的入射下被设计为携带不同拓扑荷的涡旋波束,工作中心频率为24.0 GHz.实验测试结果表明,理论设计与仿真结果吻合,从而证实了所提出的4-bit双极化编码超表面具有生成双模式涡旋波束的能力.这种超薄双模式涡旋生成器有着广泛的应用前景,特别是在图像和微波领域的无线通信系统中.