1 伊犁师范大学新疆凝聚态相变与微结构实验室, 新疆 伊宁 835000
2 伊犁师范大学振动信号俘获与智能处理重点实验室, 新疆 伊宁 835000
激光遥感探测技术具有信息传输速度快、操作方便、高精度和远距离探测等优点, 可以很好地弥补地震勘探在地形复杂区域中存在的施工难度大、地震数据采集慢等缺点。利用波前传感器具有的高灵敏度、高探测效率和离轴探测等特点, 将其用于地震波激光遥感探测之中, 改进前期研究中由于迈克尔逊干涉法存在慢变化导致的信号处理复杂等问题。通过搭建激光遥感探测系统, 对地震波中的纵波进行观测和分析, 探讨了地面振幅与波前传感器测量光斑的关系。试验表明, 该系统对低频地震波响应更加良好, 解决了仪器本身自然频率的干扰, 离轴探测的特性使得反射信号的采集更加便利, 为地震波激光遥感探测提供了试验参考。
波前传感器 激光遥感 波前 地震波 wavefront sensor laser remote sensing wavefront seismic wave
1 兰州理工大学电气工程与信息工程学院,甘肃 兰州 730050
2 甘肃省工业过程先进控制重点实验室,甘肃 兰州 730050
3 南京航空航天大学自动化学院,江苏 南京 210016
4 苏州注视科技有限公司,江苏 苏州 215000
5 珠海复旦创新研究院,广东 珠海 519031
利用三维空间直线投影到图像平面依旧为直线的特性,提出了一种基于双直线的镜头畸变参数估计方法。首先使用两条直线所对应的畸变边缘推导出了畸变参数所满足的等式,并使用实际图像的大小确定了畸变参数的分布范围。随后构建了包含畸变参数的优化目标函数,采用枚举搜索的方法得到了最佳的畸变参数。仿真和实际实验表明,提出的方法虽然仅采用了两条直线,但可以准确且有效地估计镜头畸变,相比于主流方法具有明显的优势。
机器视觉 图像处理 直线特征 畸变矫正 径向畸变 光学学报
2023, 43(13): 1315001
1 武汉科技大学城市建设学院, 武汉 430065
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
我国电解锰渣和城市生活垃圾焚烧底渣堆存量大, 污染严重, 亟需开发经济可行的资源化利用技术。采用电解锰渣和城市生活垃圾焚烧底渣制备一种路面基层材料(RBM), 并研究以不同Ca/Si比(质量比)制备的RBM的化学组成、力学性能、耐久性、浸出特性、水化产物和孔隙结构。采用X 射线衍射(XRD)、热重分析(TG)、扫描电子显微镜-能谱(SEM-EDX)和压汞等表征手段研究RBM的水化产物及微观结构, 利用浸出试验研究RBM的浸出特性。结果表明, 当Ca/Si为0.8时, RBM力学性能和孔隙结构最优, 养护7 d后的无侧限抗压强度(UCS)达9.06 MPa, 满足中国水泥土路面基层I级标准。RBM耐久性优异, 养护28 d的RBM经过9次冻融循环和干湿循环试验后, UCS分别为11.63、9.90 MPa。RBM中的主要水化产物为CaAl2Si2O8·4H2O、3CaO·Al2O3(C3A)、2CaO·SiO2(C2S)和CaMnSi4O8, 水化产物相互交错填充孔隙提高了RBM的强度及耐久性。RBM中重金属和氨氮浸出浓度符合中国地下水标准。该研究可在实现电解锰渣和城市生活垃圾焚烧底渣大规模利用的同时节约路面基层材料成本。
电解锰渣 城市生活垃圾焚烧底渣 路面基层材料 无侧限抗压强度 耐久性 浸出特性 水化产物 electrolytic manganese residue municipal solid waste incineration bottom ash road base material unconfined compressive strength durability leaching characteristic hydration product
Author Affiliations
Abstract
1 College of Science, National University of Defense Technology, Changsha 410073, China
2 Xi’an Satellite Control Center, Xi’an 710043, China
3 Tiansun Laboratory, Changsha 410073, China
4 School of Computer Science and Technology, Xidian University, Xi’an 710071, China
5 College of Electronic Science, National University of Defense Technology, Changsha 410073, China
6 Hunan Institute of Traffic Engineering, Hengyang 421099, China
For speckle-correlation-based scattering imaging, an iris is generally used next to the diffuser to magnify the speckle size and enhance the speckle contrast, which limits the light flux and makes the setup cooperative. Here, we experimentally demonstrate a non-iris speckle-correlation imaging method associated with an image resizing process. The experimental results demonstrate that, by estimating an appropriate resizing factor, our method can achieve high-fidelity noncooperative speckle-correlation imaging by digital resizing of the raw captions or on-chip pixel binning without iris. The method opens a new door for noncooperative high-frame-rate speckle-correlation imaging and benefits scattering imaging for dynamic objects hidden behind opaque barriers.
speckle correlation image resizing pixel binning Chinese Optics Letters
2023, 21(3): 031101
光子学报
2022, 51(12): 1206003
西南交通大学 电气工程学院,四川 成都 611756
该文提出了一种工作于30~32 GHz的毫米波差分移相器,其尺寸为30 mm×18 mm×0.127 mm。该移相器以微带线为基础进行设计,由中心圆环及一对开口谐振环(SRR)共同组成。通过改变中心圆环的半径大小实现在工作频段内的S参数优化。以参考线的输出相位为基准,通过改变开口谐振环半径依次实现22.5°、45°、90°的差分移相。结果表明,在所设计的频段内,该移相器的回波损耗小于-10 dB,插入损耗小于1.4 dB,仿真最大移相误差小于5°。该移相器结构简单,便于制造。通过实物样品测试,验证了其仿真结果的可靠性。
开口谐振环(SRR) 微带线 毫米波 移相器 等效电路 split resonant ring (SRR) microstrip line millimeter wave phase shifter equivalent circuit
Author Affiliations
Abstract
State Key Laboratory of Integrated Service Networks, School of Telecommunications Engineering, Xidian University, Xi’an, 710071, China
In this work, the symbol error rate (SER) performance of a relay-assisted underwater wireless optical communication (UWOC) system has been investigated over the composite exponential-generalized gamma (EGG) distribution with the beam spread function (BSF) under two hard decision schemes of fixed decision threshold (FDT) and dynamic decision threshold (DDT). Specifically, the oceanic turbulence is assumed to follow the EGG distribution, and the impacts of absorption, scattering and misalignment loss are characterized by BSF. The cumulative distribution function (CDF) of this UWOC system is derived with the max-min criterion as the best path selection scheme. And with the help of Gauss-Laguerre quadrature function, the analytical SER expressions for these two threshold schemes are then achieved and validated by Monte Carlo (MC) simulation. Moreover, the SER performance is further studied under different temperature gradients, bubble levels (BLs) and water salinity over three water types, as well as the system structure parameters. Results show that the UWOC system with DDT scheme can efficiently overcome the error floor induced by FDT scheme and demonstrates better SER performance. Furthermore, the SER performance would be improved with lower BL, temperature gradients and water salinity as well as the concentration of dissolved particles. This work will benefit the design and research of relay-assisted UWOC system.
光电子快报(英文版)
2022, 18(10): 606
红外与激光工程
2022, 51(10): 20220064
Author Affiliations
Abstract
1 Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA
2 Guangzhou Institute of Technology, Xidian University, Guangzhou 510555, China
3 Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
The efficiency of conventional quantum well light-emitting diodes (LEDs) decreases drastically with reducing areal size. Here we show that such a critical size scaling issue of LEDs can be addressed by utilizing N-polar InGaN nanowires. We studied the epitaxy and performance characteristics of N-polar InGaN nanowire LEDs grown on sapphire substrate by plasma-assisted molecular beam epitaxy. A maximum external quantum efficiency was measured for LEDs with lateral dimensions as small as 750 nm directly on wafer without any packaging. The effect of electron overflow and Auger recombination on the device performance is also studied. This work provides a viable approach for achieving high-efficiency nano and micro LEDs that were not previously possible.
Photonics Research
2022, 10(2): 02000587