“天琴计划”教育部重点实验室，天琴中心 & 物理与天文学院，天琴前沿科学中心，国家航天局引力波研究中心，中山大学(珠海校区)，广东 珠海 519082
Overview: Space gravitational wave detection missions typically consist of three identical satellites, with two laser links between the satellites at an angle of sixty degrees forming a Michelson interferometer. The arm length changes are measured using high-precision inter-satellite laser interferometry. As a key component of the inter-satellite laser interferometry system, the telescope system needs to have picometer-level optical path stability, a wavefront error of λ/30, and stray light less than 10?10 of the transmitted power. To meet the requirements of space gravitational wave detection for the telescope system, an optical and mechanical integrated analysis and optimization method is proposed to design and optimize the primary mirror and its supporting structure. The off-axis parabolic primary mirror adopts the side three-point support method, and the influence of the support point position on the mirror surface shape and the rigid body displacement under gravity conditions has been studied. Optimization of the size of the triangular lightweighting holes on the primary mirror has been performed, and density-based topology optimization has been used to optimize the support backplate while ensuring that the first-order mode of the primary mirror component remains essentially unchanged. The flexural matrix of the primary mirror component supported by a parallel bipod linkage structure was derived based on spinor theory, and an evaluation function for the support structure was established. The size parameter range of flexible support was preliminarily determined by Matlab analysis. A optical-mechanical integrated simulation platform is set up to optimize the parameters of the support structure using a weighted sum method to convert the multi-objective optimization problem into a single-objective optimization problem. The results showed that the first-order frequency of the primary mirror component system was 392.43 Hz. Under gravity and temperature loads, the deformation of the primary mirror surface was better than λ/60, the translational rigid body displacement was better than 2.5 μm, and the rotational rigid body displacement was better than 0.5 μrad, all of which met the design specifications. Under space thermal disturbance of 10 μK/Hz1/2, the size stability of the primary mirror component, represented by the displacement of the central point of the mirror, was at a level of 10 pm/Hz1/2.
引力波望远镜 Bipod连杆支撑 面形变化 尺寸稳定性 gravitational wave telescope bipod linkage support surface deformation dimensional stability
1 湖南科技大学 资源环境与安全工程学院, 湘潭411201
2 中国科学院 武汉岩土力学研究所 岩土力学与工程国家重点实验室,武汉 430071
爆破作用下硐室围岩的损伤扩展过程对硐室抗爆设计具有重要意义。为探究不同位置爆源作用下硐室围岩的损伤扩展规律, 利用有限元模拟软件ANSYS/LS-DYNA建立了顶爆、拱顶侧爆、侧爆、底部侧爆及底爆5个等爆源距数值计算模型, 对模型中的岩体采用RHT模型分析了不同位置爆源作用下硐室围岩的损伤扩展过程。在此基础上, 在模型中沿爆源至硐室边界处等距离地设置了10个振速监测点, 研究了爆源中心至硐室边界处的振动速度衰减规律。结果表明：相同爆源距不同爆源位置下硐室围岩的损伤扩展规律为首先在距爆源最近距离处出现“损伤点”, 在“损伤点”形成后, 损伤区沿着硐室边界逐步扩展, 最终形成沿硐室边界处的损伤区。相较于爆破振动速度衰减规律, 爆破振动波在硐室围岩处发生全反射, 使硐室围岩处爆破振动速度出现放大效应。同时, 爆源至硐室围岩处的损伤演化与峰值振速变化规律相互对应, 将硐室围岩处峰值振速放大效应与硐室围岩的损伤结合, 认为硐室围岩是否产生损伤可通过监测其振动速度进行确定。
不同爆源位置 RHT模型 围岩损伤 振动速度 数值模拟 different explosion source locations RHT model damage of surrounding rock vibration velocity numerical simulation
1 国防科技大学电子科学学院, 湖南长沙 410073
2 怀化学院电气与信息工程学院, 湖南怀化 418008
深度学习(DL)在语音识别、图像物体识别上取得了卓越的成效, 深度学习代替传统处理技术, 成为了研究该领域的主要处理方法。在雷达领域, 深度学习用于雷达目标识别和分类, 也取得了很好的效果, 进而, 人们试图将深度学习用于雷达成像。本文根据近几年所公开的文献资料, 按照雷达成像的特点, 分类介绍深度学习用于雷达成像的研究进展; 之后, 对深度学习用于雷达成像的可行性、样本选取、泛化以及成像质量的评价等开放性问题提出了作者的设想, 并对深度学习用于雷达成像进行了展望。
深度学习 雷达成像 可行性 样本 泛化 Deep Learning radar imaging feasibility samples generalization 太赫兹科学与电子信息学报
2023, 21(9): 1086
国防科技大学电子科学学院, 湖南长沙 410073
基于逆合成孔径雷达(ISAR)图像序列的卫星目标姿态估计是一项具有重大意义且富有挑战性的任务。现有的估计方法通常是基于图像中关键角点或线性部件的提取, 较难满足实时需求, 且都未能充分利用目标成像特性先验。本文提出一种基于成像特性与回归网络的卫星目标姿态估计方法: 提前确定各种姿态下的卫星目标成像特性, 并作为后续数据集标注的理论基础; 区别于传统的分类问题, 建立一种适用于姿态估计的回归网络与估计框架。采用毫米波频段的电测仿真计算数据对所提方法进行验证, 结果表明, 单张图像中估计的平均姿态误差可以控制在3.5 °以内。
逆合成孔径雷达 成像特性 回归网络 姿态估计 实时预估 Inverse Synthetic Aperture Radar(ISAR) imaging characteristics regression network attitude estimation real-time prediction 太赫兹科学与电子信息学报
2023, 21(4): 572
光学 精密工程
2023, 31(23): 3438
Author Affiliations
Abstract
1 Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon Hong Kong, People’s Republic of China
2 Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon Hong Kong, People’s Republic of China
3 Department of Physics, The Chinese University of Hong Kong, New Territories Hong Kong, People’s Republic of China
Si is a promising anode material for Li ion batteries because of its high specific capacity, abundant reserve, and low cost. However, its rate performance and cycling stability are poor due to the severe particle pulverization during the lithiation/delithiation process. The high stress induced by the Li concentration gradient and anisotropic deformation is the main reason for the fracture of Si particles. Here we present a new stress mitigation strategy by uniformly distributing small amounts of Sn and Sb in Si micron-sized particles, which reduces the Li concentration gradient and realizes an isotropic lithiation/delithiation process. The Si8.5Sn0.5Sb microparticles (mean particle size: 8.22 μm) show over 6000-fold and tenfold improvements in electronic conductivity and Li diffusivity than Si particles, respectively. The discharge capacities of the Si8.5Sn0.5Sb microparticle anode after 100 cycles at 1.0 and 3.0 A g-1 are 1.62 and 1.19 Ah g-1, respectively, corresponding to a retention rate of 94.2% and 99.6%, respectively, relative to the capacity of the first cycle after activation. Multicomponent microparticle anodes containing Si, Sn, Sb, Ge and Ag prepared using the same method yields an ultra-low capacity decay rate of 0.02% per cycle for 1000 cycles at 1 A g-1, corroborating the proposed mechanism. The stress regulation mechanism enabled by the industry-compatible fabrication methods opens up enormous opportunities for low-cost and high-energy–density Li-ion batteries.
Nano-Micro Letters
2023, 15(1): 222
1 贵州电网有限责任公司电力科学研究院, 贵州贵阳 550002
2 贵州电网有限责任公司, 贵州贵阳 550001
3 海南电网有限责任公司电力科学研究院, 海南海口 570100
4 贵州电网有限责任公司贵阳供电局, 贵州贵阳 550002
输变电设施的金属构件容易受温度、湿气等气候因素影响而发生侵蚀, 因此通常需要在其表面喷涂耐候保护涂层。为了确保涂层厚度符合要求, 需要对其进行检测。针对现有检测方法的不足, 本文采用锁相红外无损检测技术对耐候涂层厚度进行检测与评估。首先采用制作的标准涂层试件对该方法测厚的原理与重复性进行验证, 验证了该技术对涂层厚度的评估的可靠性与稳定性; 其后采用厚度均匀过渡的耐候涂层试片进行测试, 采用试片上定标点的相位值拟合出定标曲线, 并利用该曲线测量出试片上验证点的厚度信息。实验结果表明, 测量厚度与真实厚度误差在± 5%以内, 采用相位图像可以对耐候涂层厚度与均匀度进行有效测量与评估。
锁相红外 涂层厚度 耐候涂层 相位图 lock-in thermography, coating thickness, weather r
1 西京学院信息工程学院，陕西西安 710123
2 空军工程大学防空反导学院，陕西西安 710046
3 空军工程大学研究生院，陕西西安 710046
为了对临近空间高超声速飞行器进行有效探测和预警，以 X-51A为例，计算火箭助推段、超燃发动机工作段和无动力滑翔段、飞行器蒙皮、喷管和尾焰的双波段红外辐射特性。红外辐射计算的关键在于温度和有效辐射面积的确定。根据修正 Lees驻点热流密度方法和辐射平衡时的辐射传热公式，计算出蒙皮的温度。用加力燃烧的涡喷发动机模型近似计算喷管的温度。把导弹尾焰温度分布场模型进行三段式简化，模拟出尾焰的红外辐射特性。仿真结果表明，在 X-51A的不同飞行阶段，从不同探测角度观察到的各辐射部位对总体红外辐射贡献率差异较大；速度对蒙皮的红外辐射影响较大，而喷管和尾焰的红外辐射与火箭和超燃冲压发动机的燃烧状态有关。分析指出，当高超声速飞行器飞行姿态发生变化，或者在不同的飞行阶段，更适合采用双波段进行探测。
红外辐射 高超声速飞行器 驻点热流 蒙皮 喷管 尾焰 infrared(IR) radiation, hypersonic vehicles, stagn
