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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • LED stage lighting
  • CRI
  • RGBW four-color mixing model
  • the blackbody locus fitting
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Communication University of China
416 条数据
?? 中文（中国） ▾

  • Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection

    摘要： Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W?1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W?1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.

    关键词： single-crystal core/shell,AlN,ZnO nanowires,ultraviolet emission,dual-color ultraviolet photodetection

    更新于2025-09-23 15:23:52

  • Tea Diseases Detection Based on Fast Infrared Thermal Image Processing Technology

    摘要： The overall goal of this study is to develop an effective, simple, aptly computer vision algorithm to detect tea disease area using infrared thermal image processing techniques and to estimate tea disease. This paper finds that the area of tea disease has certain regularity with its infrared image gray distribution. Using this rule, we extracted two characteristic parameters into a classifier to help achieve rapid tea disease detection, which increase the accuracy of detection a small amount. Tea plant images were taken from Jiangsu Tea Expo Park, China during daylight and the tea disease detection algorithm were tested on 116 images collected from 57 trees. The tea disease detection algorithm consisted of the following steps: classify canopy infrared thermal image, convert red, green and blue (RGB) image to hue, saturation and value (HSV), thresholding, color identification, noise filtering, binarization, closed operation and counting. A correlation coefficient of 0.97 was obtained between the tea disease detection algorithm and counting performed through human observation, 2% higher than traditional algorithms without classifiers.

    关键词： Color detection,Tea disease,Infrared thermal image,Fast classification,Image processing

    更新于2025-09-23 15:23:52

  • Controlling self-assembling and color-transition of polydiacetylene/zinc(II) ion/zinc oxide nanocomposites by varying pH: Effects of surface charge and head group dissociation

    摘要： Polydiacetylene/zinc(II) ion/zinc oxide (PDA/Zn2+/ZnO) nanocomposite exhibits reversible thermochromism and dual colorimetric response to acid/base. This contribution presents our ongoing development of the PDA/Zn2+/ZnO nanocomposite for sensing applications by controlling ZnO surface charge and dissociation of PDA headgroup via pH adjustment. At pH >10, negative ZnO surface charge and PDA carboxylate headgroup significantly enhance molecular organization during the self-assembling process. An increase of the nanocomposite amount after photopolymerization is observed. Oppositely, pH <6 results in irreversible-thermochromic nanocomposites. Additionally, the nanocomposites prepared at different pH change color at different concentrations of chemical stimuli. Molecular packing, local interactions and PDA conformation are investigated.

    关键词： self-assembling,color transition,sensor,polydiacetylene,dissociation,surface charge

    更新于2025-09-23 15:23:52

  • Quaternion-based weighted nuclear norm minimization for color image denoising

    摘要： The quaternion method plays an important role in color image processing, because it represents the color image as a whole rather than as a separate color space component, thus naturally handling the coupling among color channels. The weighted nuclear norm minimization (WNNM) scheme assigns different weights to different singular values, leading to more reasonable image representation method. In this paper, we propose a novel quaternion weighted nuclear norm minimization (QWNNM) model and algorithm under the low rank sparse framework. The proposed model represents the color image as a low rank quaternion matrix, where quaternion singular value decomposition can be calculated by its equivalent complex matrix. We solve the QWNNM by adaptively assigning different singular values with different weights. Color image denoising is implemented by QWNNM based on non-local similarity priors. In this new color space, the inherent color structure can be well preserved during image reconstruction. For high noise levels, we apply a Gaussian lowpass filter (LPF) to the noisy image as a preprocessing before QWNNM, which reduces the iteration numbers and improves the denoised results. The experimental results clearly show that the proposed method outperforms K-SVD, QKSVD and WNNM in terms of both quantitative criteria and visual perceptual.

    关键词： Quaternion singular value decomposition,Non-local similarity priors,Quaternion weighted nuclear norm minimization,Low rank,Color image denoising

    更新于2025-09-23 15:23:52

  • Promising red emission from functionalized Polypyrrole/CaTiO3:Eu3+ nano-composites for photonic applications

    摘要： CaTiO3:Eu3+ luminescent nanoparticles (NPs) and Ppy/CaTiO3:Eu3+ nanocomposites (NCs) are synthesized via combustion and solution casting techniques respectively and their structural and optical properties are investigated. The powder X-ray diffraction patterns of the as-formed products show single orthorhombic phase. The crystallite size measurement is assessed utilizing Scherrer's technique and observed to be in the range of 40–45 nm. The impact of Eu3+ ions on luminescence properties of the produced nanophosphors is examined the outcomes are given in detail. The phosphors displayed splendid red emission at 398 nm excitation. The emission peaks observed at 540, 593, 615, 653, 696 and 706 nm (5D0→7Fj = 0, 1, 2, 3, 4, 5) are assigned to Eu3+ ions transitions. The electronic transition equivalent to 5D0→7F2 (615 nm) is robust than the magnetic dipole transition 5D0→7F1 of Eu3+ ions (596 nm). The CIE chromaticity co-ordinates are ascertained from emanation spectra, the obtained values are very close to NTSC standard value of red emission. Hence, the present phosphors are exceedingly valuable for display applications. The obtained results demonstrate that Ppy-assisted solution casting is an effective methodology for the synthesis of rare-earth doped CaTiO3:Eu3+ nanocomposites (NCs).

    关键词： Diffuse reflectance,Microbial activity,Nanocomposites,Color diagrams,Polypyrrole

    更新于2025-09-23 15:23:52

  • Optical investigation of radiation-induced color centers in lithium fluoride thin films for low-energy proton-beam detectors

    摘要： In the last few years, the peculiar photoluminescence properties of radiation-induced color centers in lithium fluoride (LiF) films have been successfully used for advanced diagnostics of low-energy proton beams produced by the TOP-IMPLART linear accelerator for protontheraphy under development at ENEA C.R. Frascati. The two-dimensional spatial dose map of the transversal section of proton beams was fully reconstructed in a wide interval of doses. In this work the optical emission properties of LiF thin films, grown by thermal evaporation on glass and Si (100) substrates and subsequently irradiated by proton beams of nominal energy 3 MeV at doses higher than 105 Gy, were carefully investigated. Their structural and morphological analyses were performed by X-ray diffraction and atomic force microscopy. A careful comparison of the photoluminescence and photoluminescence-excitation spectra of F2 and F3+ electronic defects was performed. Substrate-enhanced photoluminescence intensity increase up to 100% was observed in colored LiF films grown on Si substrates with respect to glass ones. This behavior can be substantially ascribed to the reflective properties of the Si substrate at the emission wavelengths of F2 and F3+ CCs, although other complex effects due to the polycrystalline nature of the films cannot be excluded.

    关键词： Photoluminescence,Lithium fluoride,Radiation detectors,Color centers,Thin films

    更新于2025-09-23 15:23:52

  • Color image encryption method based on 2D-variational mode decomposition

    摘要： In order to reduce the correlation between adjacent pixels in a plaintext image, and to solve the small key space problem of image encryption algorithms when a low-dimension chaotic map is used, a new encryption method for color images is proposed based on two-dimensional variational mode decomposition (2D-VMD) combined with eight-dimensional (8D) hyper-chaotic systems. 2D-VMD decomposes R, G and B components of a color image respectively. The 8D hyper-chaotic system is constructed by means of variable coupling. After improving and combining the original sequences obtained by iterating the system, two groups of key sequences associated with the plain-image are obtained. One group is used to scramble each mode image obtained by 2D-VMD; the other is used to replace the pixel values of the scrambled mode images. For different mode images, different key sequences are adopted. The encrypted images whose number is equal to the number of the modes can then be obtained. The experimental results show that, compared with the existing methods, the correlation coefficients between the pixels in the spatial domain of the plain-image can be reduced by 2D-VMD, as it’s more difficult to crack. In addition, the encryption method has better statistical and differential characteristics, as well as large enough key space, and better plain-image sensitivity.

    关键词： Encryption method,Image decomposition,Two-dimensional variational mode decomposition,Color image,Hyper-chaotic system

    更新于2025-09-23 15:23:52

  • Color removal from wastewater by photocatalytic process using titanium dioxide-coated glass, ceramic tile, and stainless steel sheets

    摘要： Dye pollutants from textile industries are a major wastewater problem because they have complex chemical structures. Photocatalysis is a promising wastewater treatment method, which is used to remove dyes under light irradiation in the presence of a photocatalyst. In this article, titanium dioxide (TiO2) photocatalyst was synthesized through sol-gel technique and coated on different substrates (i.e. transparent glass, glazed ceramic tile, and stainless steel) by doctor blade technique. The coated substrates were used in an innovative reactor to remove colors in dye wastewater. The photocatalytic activities of the designed reactor were determined using a synthetic dye wastewater (methylene blue) under UV irradiations (36W-UVA or 30W-UVC lamps). The results showed that the optimum substrate yielded the highest color removal efficiency (93.03 ± 0.66%) was TiO2-coated glass under UVC irradiation. The recycling ability of TiO2-coated glass sheet was also evaluated. It was found that TiO2-coated glass sheet provided the same efficiencies for 20 cycles. In addition, the actual wastewater from textile industry was tested in this study with different pH values (i.e. pH = 3e11). The maximum color removal obtained was 87.86 ± 0.23% at pH value 11 on TiO2-coated glass under UVC irradiation. The color removal was found to decrease with decreasing pH.

    关键词： Photocatalysis,Color removal,Wastewater treatment,Titanium dioxide,Dye wastewater

    更新于2025-09-23 15:23:52

  • [IEEE 2018 Colour and Visual Computing Symposium (CVCS) - Gj?vik (2018.9.19-2018.9.20)] 2018 Colour and Visual Computing Symposium (CVCS) - Photorealistic Style Transfer for Cinema Shoots

    摘要： Color grading is the process of subtly mixing and adjusting the color and tonal balance of a movie to achieve a specific visual look. This manual editing task may require a significant amount of work from very skilled artists and technicians. In many cases the director wants to emulate the style and look present in a reference image, e.g. a still from an existing movie, a photograph, or even a previously shot sequence in the current movie. In this paper we propose a method that automatically transfers the style, in terms of tone, color palette and contrast, from a reference image to the source RAW image. It consists of three separable operations: global luminance matching, global color transfer and local contrast matching. The computational complexity of the procedure is extremely low and allows for real-time implementation in-camera. As it just takes into account the statistics of source and reference images, no training is required. The results are free from artifacts and provide an excellent approximation to the intended look, bringing savings in pre-production, shooting and post-production time.

    关键词： computational photography,color grading,Image processing,visual look,style transfer

    更新于2025-09-23 15:23:52

  • [IEEE 2018 International Conference on Applied Engineering (ICAE) - Batam, Indonesia (2018.10.3-2018.10.4)] 2018 International Conference on Applied Engineering (ICAE) - Vision Based Flame Detection System For Surveillance Camera

    摘要： Flame detection systems are useful for the development of fire early detection systems. In general, conventional fire detection system which is usually used heat detector cannot detect the presence of fire since the detector requires much time to detect temperature changes. The use of a camera as an image scanner sensor has the potential to be used as an identifier of a flame shape or color. This study aims to build an image processing flame detection system using image enhancement, segmentation and filtering methods which is applied the Vission Assistant available in LabVIEW. The system implemented in a frame rate of 30 fps with a resolution of 1024 x 768, in which the system accuracy reach up to 98%.

    关键词： Image Enhancement,Color Filtering,LabVIEW,HSV Filtering,Flame Detection

    更新于2025-09-23 15:23:52