Using a Novel and Easy-to-Use Sandwich Structure Device to Evaluate the Cooling Properties of Cool Materials

A number of cool materials have been designed and used in hot weather to minimize the heat coming from sunlight. Traditionally, solar reflectance and infrared emittance were measured to characterize the cooling properties of cool materials. However, these methods could represent the cooling property only indirectly. In this work, a sandwich structure device that can straightforwardly measure the cooling properties of cool materials was designed. Two cool materials, including high-density polyethylene (HDPE) and polyvinyl chloride (PVC), were selected to verify the device. For the purpose of comparison, UV-vis-NIR spectral characterization was also used to evaluate the cooling properties of the selected materials. The results, especially for the HDPE/Green 260 composite sample, which presents much lower solar reflectance but better cooling property, indicated that the cooling properties cannot be entirely represented by only the reflectance or transmittance, and the sandwich structure device was able to make up for this deficiency.     

Summary of ISO/TC 201 standard: ISO 19668—Surface chemical analysis—X‐ray photoelectron spectroscopy—Estimating and reporting detection limits for elements in homogeneous materials

This International Standard specifies a procedure by which elemental detection limits in X‐ray photoelectron spectroscopy (XPS) can be estimated from data for a particular sample in common analytical situations and reported. This document is applicable to homogeneous materials and is not applicable if the depth distribution of elements is inhomogeneous within the information depth of the technique.     

一种基于多尺度卷积神经网络和分类统计的图像去雾霾方法

传统的去雾霾方法会导致天空、白云和明亮区域内的颜色失真。为了解决以上问题,提出了一种基于多尺度卷积神经网络和分类统计的去除图像雾霾的方法。首先用多尺度卷积神经网络估计图像的透射率,其次对所估计的透射率进行分类统计以确定在暗通道内天空、白云和明亮区域的像素值,最后通过低通高斯滤波器平滑图像场景的辐射度,得到恢复的无雾霾图像。实验结果表明,采用提出的方法对图像去雾霾后明亮区域内的颜色不会失真,且保留了图像的自然外观,对合成图像和真实图像均有较好的去雾霾效果。     

氮气流量对磁控溅射C掺杂TiO2薄膜光学性能的影响

采用磁控溅射法制备了C掺杂TiO₂薄膜,并研究了氮气引入溅射过程对薄膜光学性能的影响。利用X射线衍射仪、拉曼光谱仪、X射线光电子能谱仪、分光光度计和原子力显微镜分析了不同氮气流量下薄膜的微结构、元素价态、透光性能和表面形貌。结果表明,沉积的薄膜主要是非晶结构,拉曼光谱中存在少量锐钛矿相,且随着氮气流量增大,锐钛矿特征峰强度减弱,意味着晶粒出现细化。当氮气流量增大为4cm³/min时,C掺杂TiO₂薄膜内氮元素含量为3.54%,其光学带隙从3.29eV变化至3.55eV,可见光区的光学透过率明显提高。可见改变氮气流量可实现对C掺杂TiO₂薄膜光学带隙和光吸收率的有效调控。     

土壤中Pb、Cr元素激光诱导击穿光谱技术定量分析

采用激光诱导击穿光谱技术(Laser-induced b reakdown spectroscopy,LIBS)对土 壤样品中的Pb和Cr元素进行了分析,以PbI280.17 nm和CrI425.43 nm作为分析线,优化了透 镜到样品的距离(Lens to sample distance,LTSD)、延迟时间对光谱信号强度及信噪比 SNR 的影响。在最佳实验条件下,对两种元素的谱峰强度和元素浓度进行分析,针对外标法 和内标法分别建立了谱线峰值强度、谱线峰值积分面积与对应元素浓度的定标曲线。采用谱 线峰值积分面积法对土壤中重金属Pb和Cr元素的检测,相比于外标法,内标法将Pb和Cr元素 最大相对误差分别从13.56%和12.68%降低到了 6.7%;Pb和Cr元素定标曲线的拟合相关 系数R²分别从0.978和0.975提高到了0.996和0.991。实 验结果表明:采用LIBS技术对土 壤中Pb、Cr元素检测具有可行性,采用谱线峰值积分面积的内标法,可以降低最大相对误差 并提高测量精度。     

基于回归分析的迎峰度夏用电量分析

利用回归分析算法,提出了一种迎峰度夏期间最高气温与日用电量关系分析方法,首先利用皮尔森相关系数对度夏期间的最高气温和日用电量相关程度进行定量分析,然后利用回归分析算法建立最高气温和日用电量的拟合函数,并利用最小二乘法进行求解,得到最高气温和日用电量相关关系的定量分析结果。研究结果表明,提出的度夏期间用电量分析方法能够定量地给出气温变化导致的用电量变化情况,并能根据分析结果对未来几天的日用电量进行准确预测。     

海面弱小目标红外检测算法的高速实现

为了实现红外图像中海面弱小目标的精确检测, 提出了一种基于局部峰值检测和管道滤波 的红外图像处理算法。首先采取局部峰值检测提取疑似目标,然后根据自适应域值处理 去除多数非目 标峰值,最后通过管道滤波法排除残留干扰以准确识别目标。针对算法中包括大量条件判断 和并行计算的 特点,通过比对CPU和GPU的工作特性,最终采用CPU-GPU协作的异构计算模型对算法进 行了加速。 实验结果表明,在大量海面杂波的干扰下,该加速检测算法运行后的目标检测漏警率不高于 3.5%,虚警率 不高于5%,加速比为26,处理分辨率为640 ×512图像的速率不低于32帧/秒,具有很高的 工程应用价值。     

Highly Sensitive Mechanoresponsive Smart Windows Driven by Shear Strain

Advanced optical materials with rational designs and tunable light transmission have been drawing increasing interest due to their great potential in energy-efficient buildings and on-demand optical devices. Mechanoresponsive smart windows (SWs) can modulate light transmittance by mechanical actuation, showing high energy efficiency, low cost, and chemical stability. However, current research mainly focuses on tensile strain-responsive SWs that typically require a large strain to achieve optical transparency switching-which causes great inconvenience to practical application and fatigue damage to matrix materials. Herein, a novel shear-responsive SW with high strain sensitivity is fabricated by vertically fixing a Fe₃O₄@SiO₂ nanochains (NCs) array in an elastic polyacrylamide matrix. The flexible SW exhibits optically transparent with all NCs standing vertically to the SW surface at initial relaxation state, which enables a good shielding effect, with NCs tilting along the shearing direction as the strain applied. Critically, a rather small shear displacement (1.5 mm) applied on the surface of SW gives rise to tunable optical states varying from the transparency state of 65% transmittance to the opaque state of 10%. The as-prepared SW with novel tuning modulation, high shear strain sensitivity, and optical angle-dependence holds promising potential in smart windows, optical switches, anti-voyeurism, and etc.