Display illumination with modulated directional backlight

Illumination is essential for modern life as colorful world is perceived by human visionary system. Display technology has been developing rapidly in recent decades, and the basic principle is related to the way that the image is illuminated and light is emanated. Traditional illumination is provided by different types of light sources, and the display image is visible in large viewing space until the emanating light decays to zero. This work proposes and demonstrates a novel illumination scheme for a display in which the displaying images are visible only in specific spatial regions. The directional backlight ensures the image propagating to specific direction while imaging visibility can be controlled to terminate abruptly at certain distance from the display screen while exerting no influence to nearby regions. The working principle for such an illumination scheme is the use of the modulated coherent directional backlight through an axicon lens. It is shown that the illumination scheme can robustly deliver carried image information to the designated viewing region. This new illumination scheme has many advantages over conventional illumination, including its usage for personal display, very lower energy consumption, as well as minimizing light hazard pollution.     

UV-enhanced conductive and dielectric properties in KTN crystal

We observe enhancements of both conductive and dielectric properties under UV illumination by using a ferroelectric absorber, potassium tantalate niobate (KTa_1-xNb_xO₃, KTN). The UV-generated electron-hole pairs weaken the intrinsic ferroelectric polarization while enhance the conductive property. The UV-induced heat effect causes the enhancement of the dielectric property. The results are further confirmed by the maximal rectification ratio which shows an opposite trend between the direct heating process and the UV illumination. Our results are useful for better understanding of ferroelectric properties under UV illumination and the development of new optoelectronic devices.     

Artistic Augmentation of Photographs with Droplets

Journal of Computer Science and Technology - Artistic augmentation of photographs with water droplets aims at generating aesthetic yet realistic images, and thus differs from traditional augmented...     

Solution processed,vertically aligned,AZO nanocolumn array for chemiresistive sensor application with UV-enhanced sensitivity

In this work, a wide and highly sensitive chemiresistive sensor has been developed based on the AZO nanocolumn array film. This is meant for the room detection of H₂O₂ under UV illumination. A cost-effective one step multi-layers growth process was adopted for the synthesis of the AZO nanocolumn array. The experimental studies were done by scanning electron microscopy (SEM), transmission and electron microscopy (TEM).Then X-ray diffraction confirmed that the AZO column array was closely packed, connected, vertically aligned, and polycrystalline, with a high surface area. This structure ensures better electrical conduction over random and separated nanostructures. The hall-effect measurement indicates that the AZO film was n-type, with high conductivity (3.60 × 10³ Ωcm), high carrier density (11.3 × 10²⁰cm⁻³) and with acceptable mobility (0.95 cm²/Vs). The x-ray photoemission spectroscopy suggests that the AZO film consists of a large amount of adsorbed oxygen-related species at the sheath layer of the thin-film, which is vital for sensors. By the UV light activation, sensors based on the AZO nanocolumn array exhibited enhanced H₂O₂ detection properties at room temperature. At a concentration from 15 μM to 30 mM, H₂O₂ sensitivity evaluated by relative response was remarkably increased from 15% to 36%. The operation under ambient conditions and wide range sensing shows that this chemiresistive AZO sensor is adequate for biomedical and environmental applications.     

具有光照鲁棒的图像匹配方法

针对现有的基于局部特征的图像匹配算法对光照变化敏感、匹配正确率低等问题，提出一种具有光照鲁棒性的图像匹配算法。首先使用实时对比保留去色（RTCP）算法灰度化图像，然后利用对比拉伸函数模拟不同光照变换对图像的影响从而提取抗光照变换特征点，最后采用局部强度顺序模式建立特征点描述符，根据待匹配图像局部特征点描述符的欧氏距离判断是否为成对匹配点。在公开数据集上，所提算法与尺度不变特征变换（SIFT）算法、加速鲁棒特征（SURF）算法、"风"（KAZE）算法和ORB算法在匹配速度和匹配正确率上进行了对比实验。实验结果表明：随着图像亮度差异的增加，SIFT算法、SURF算法、"风"（KAZE）算法和ORB算法匹配正确率下降迅速，所提算法下降缓慢并且正确率均高于80%；所提算法特征点检测较慢和描述符维数较高，平均耗时为23.47 s，匹配速度不及另外四种算法，但匹配质量却远超过它们。对实时性要求不高的系统中，所提算法可以克服光照变化对图像匹配造成的影响。     

Stress distribution in thick-walled cylinder due to non-uniform radial pressure on the example of reinforcement corrosion in concrete

This paper presents an analytical solution to the non-uniform pressure on thick-walled cylinder. The formulation is based on the linear elasticity theory (plain strain) and stress function method. As an example, the proposed solution is used to model the stress distribution due to non-uniform steel reinforcement corrosion in concrete. The model is formulated considering different scenarios of corrosion pressure distribution. It is validated against the finite element model for different cases of non-uniform pressure distributions. The results show that the corrosion-induced cracks are likely to start just beyond the anodic zone. This is confirmed by the experimental tests on concrete cylinder exposed to non-uniform accelerated corrosion of steel reinforcement. The model can be effectively used to calculate the distribution of corrosion-induced stresses in concrete.     

Chromatic adaptation in a 2D photograph demonstrated by a D‐up viewer

It is said that we cannot have color constancy in a photograph. The concept of recognized visual space of illumination (RVSI) asserts that chromatic adaptation occurs when one perceives the illumination that is filling a space and not the objects in the space. It predicts then that if one perceives a 3D scene in a photograph, then color constancy will occur in the photograph. In this work, a dimension‐up (D‐up) viewer was developed to perceive a 3D scene on a 2D photograph, and the effect of chromatic adaptation was measured by the color appearance of a gray patch placed at the center of the photograph. Subjects saw the patch as a vivid color when they saw a photograph that had been taken under colored illumination, which is a normal experience in a real space observation. When the color appearance was measured by the elementary color naming method, the amount of chromaticness of the patch in percentage and the apparent hue were very similar to those observed in the 2‐room technique, thus confirming the prediction by the RVSI theory.     

Recursive least squares estimation methods for a class of nonlinear systems based on non-uniform sampling

Many dynamic processes in practice have nonlinear characteristics and must be described by using nonlinear models. It remains to be a challenging problem to build the models of such nonlinear systems and to estimate their parameters. This article studies the parameter estimation problem for a class of Hammerstein-Wiener nonlinear systems based on non-uniform sampling. By means of the auxiliary model identification idea, an auxiliary model-based recursive least squares algorithm is derived for the systems. In order to enhance the computational efficiency, an auxiliary model-based hierarchical least squares algorithm is proposed by utilizing the hierarchical identification principle. The simulation results confirm the effectiveness of the proposed algorithms.     

粗化床面非均匀沙推移质运动扩散特性研究

对泥沙颗粒运动规律的把握是准确估算推移质输沙率的基础。本文开展了粗化床面条件下的水槽试验，分析了非均匀沙颗粒的均方位移和速度自相关系数变化，并与已有均匀沙试验进行了对比。结果表明，粗化床面存在着由单个或多个粗颗粒组成的粗化结构体，形成比平整床面更复杂的底部边界，粗化结构体对泥沙颗粒运动造成较大影响，颗粒在运动过程中与水流动量交换强度大，泥沙颗粒运动与均匀沙试验“类弹道扩散”存在一定差异；受床面结构影响，部分颗粒表现出较强的横向运动，颗粒的横向扩散特性与流向扩散特性类似。与均匀沙平整床面不同，粗化床面上颗粒运动可能会相应改变床面结构，从而改变水流底部边界条件，进而对泥沙颗粒运动造成影响，泥沙颗粒运动存在较明显的记忆效应和反常扩散现象。     

The effect of titanium dioxide-supported CdSe photocatalysts enhanced for photocatalytic glucose electrooxidation under UV illumination

The wetness impregnation method was used to synthesize 0.1% CdSe/TiO₂ photocatalysts with different atomic molar ratios (90–10, 70–30, 50–50, and 30–70). These catalysts were characterized by XRD, SEM-EDX and mapping, TEM-EDS, UV–VIS spectroscopy, fluorescence spectroscopy, XPS, TPR, TPO, and TPD analyses. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses were performed to examine the photocatalytic activity for photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO₂ formed the catalyst and electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results demonstrate that the 0.1% CdSe(50-50)/TiO₂ catalyst has higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (2.71 mA cm^?2) and under UV illumination (7.20 mA cm^?2). These results offer a promising new type of photocatalyst for PFC applications.