1 青岛理工大学土木工程学院,山东 青岛 266033
2 江苏科技大学土木工程与建筑学院,江苏 镇江 212100
服役于氯盐和硫酸盐耦合环境的钢筋混凝土结构,很容易因为氯盐和硫酸盐的侵蚀引起性能退化。本文从氯盐和硫酸盐的侵蚀机理出发,系统地分析了硫酸盐侵蚀造成混凝土损伤前后氯离子和硫酸根离子的扩散-结合过程。基于经典的扩散-反应模型以及化学-损伤-传输理论框架,详细阐述离子活度、环境温湿度、微观结构、钙溶蚀等因素对化学-损伤-传输体系的影响,并从热力学角度介绍了氯离子和硫酸根离子耦合传输的热力学模型。基于上述分析,对目前研究存在的问题进行了展望。
混凝土 氯盐-硫酸盐 扩散-反应 化学-损伤-传输体系 concrete chloride-sulfate diffusion-reaction chemo-damage-transport system
红外与激光工程
2022, 51(1): 20210935
精密测试技术及仪器国家重点实验室,清华大学精密仪器系, 北京 100084
由于现有空间光调制器(SLM)的调制特性,连续取值的复振幅型计算全息图(CGH)通常需要被转换为离散取值的纯振幅型或纯相位型CGH。将连续值近似为离散值的量化过程会对CGH的全息重建质量产生显著的影响。选择峰值信噪比(PSNR)作为重建质量的评价依据,采用参数空间遍历法,定量评估了CGH振幅和相位的量化取值对重建质量的影响。评估过程充分考虑了分辨率、补零范围、重建距离、重建波长、随机相位、像素间距、位深度及相位调制偏差等关键参数对全息重建的作用。在此基础上,提出了针对现有和未来SLM的最佳量化方案。
全息 计算全息 全息显示 振幅 相位 量化 中国激光
2021, 48(12): 1209002
Author Affiliations
Abstract
1 State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
2 Centre for Photonic Devices and Sensors, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK
This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms (DPHs) for overcoming the limit of the space-bandwidth product (SBP) delivered by existing methods. To construct DPHs, two spatially macro-pixel encoded phase components are employed in the SBP-preserved resampling of complex holograms. Four generated sub-DPHs are displayed sequentially in time for high-quality holographic image reconstruction without reducing the image size or discarding any image terms when the DPHs are interweaved. The reconstructed holographic images contain more details and less speckle noise, with their signal-to-noise ratio and structure similarity index being improved by 14.64% and 78.79%, respectively.
computer generated holography complex-amplitude hologram double phase hologram holographic display Chinese Optics Letters
2020, 18(10): 100901