- 标题
- 摘要
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- 实验方案
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Cloud removal in remote sensing images using nonnegative matrix factorization and error correction
摘要： In the imaging process of optical remote sensing platforms, clouds are an inevitable barrier to the effective observation of sensors. To recover the original information covered by the clouds and the accompanying shadows, a nonnegative matrix factorization (NMF) and error correction method (S-NMF-EC) is proposed in this paper. Firstly, a cloud-free fused reference image is obtained by a reference image and two or more low-resolution images using the spatial and temporal nonlocal filter-based data fusion model (STNLFFM). Secondly, the cloud-free fused reference image is used to remove the cloud cover of the cloud-contaminated image based on NMF. Finally, the cloud removal result is further improved by error correction. It is worth noting that cloud detection is not required by S-NMF-EC, and the cloud-free information of the cloud-contaminated image is maximally retained. Both simulated and real-data experiments were conducted to validate the proposed S-NMF-EC method. Compared with other cloud removal methods, the results demonstrate that S-NMF-EC is visually and quantitatively effective (correlation coefficients ≥ 0.99) for the removal of thick clouds, thin clouds, and shadows.
关键词： Nonnegative matrix factorization,Multitemporal,Optical remote sensing image,Error correction,Cloud removal
更新于2025-09-23 15:23:52
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Novel polyelectrolyte–Al2O3/SiO2 composite nanoabrasives for improved chemical mechanical polishing (CMP) of sapphire
摘要： A new type of polyelectrolyte–Al2O3/SiO2 composite nanoparticle with excellent dispersibility and superior polishing performance was successfully fabricated using a facile method. Silica acted as a bifunctional molecule by attaching to alumina via covalent bond and adsorbing polyelectrolytes by electrostatic interaction. The material removal rate of the polyelectrolyte–Al2O3/SiO2 abrasive was 30% higher than that of the pure Al2O3 abrasive. In addition, the sapphire surface was much smoother. The material removal mechanism was investigated during CMP using the microcontact and wear model. The enhanced removal rate was mainly attributed to the well-dispersed particles, which can accelerate mechanical removal process. The remarkably smooth surface was due to the decrease in penetration depth of the abrasive into the wafer. The results of this study provided a feasible strategy to satisfy the high efficiency and damage-free polishing requirements for sapphire planarization.
关键词： chemical mechanical polishing,composite abrasives,polyelectrolyte,surface roughness,sapphire,material removal rate
更新于2025-09-23 15:22:29
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A Novel Hybrid Removal Technology for High-Aspect-Ratio SU-8 Micromolds in ECF (Electro-Conjugate Fluid) Micropumps Fabrication by UV-LIGA
摘要： Previously, we have developed ECF micropumps with triangular prism and slit electrode pairs (TPSEs) fabricated by the UV-LIGA. However, the previous KMPR molds have a limit to attain higher-aspect-ratio TPSEs. As a promising substitute, the ultrathick SU-8 molds are preferable for the TPSEs due to higher-aspect-ratio ability, but their difficult removal remains an annoying problem. To solve this problem, we first propose a novel hybrid removal method combining CO2 laser engraving with O2/CF4 plasma to achieve the fast, non-swelling, and complete removal of ultrathick SU-8 micromolds for higher-aspect-ratio TPSEs. The CO2 laser engraving is utilized as the main process to remove most SU-8, while the O2/CF4 plasma is adopted as the post-treatment to remove the remaining SU-8. To gather the proper fabrication conditions, we quantitatively analyze the effects of laser power, laser scan speed, and laser-pass numbers on the SU-8 ablation thickness. We successfully fabricated TPSEs of 590 μm and 970 μm in height by selectively removing SU-8 micromolds of 620 and 1100 μm in thickness. This achievement confirmed that our hybrid removal technology could remove the crosslinked SU-8 effectively and efficiently. We further experimentally proved the fascinating potential of our hybrid removal in improving the output performance of ECF micropumps. This promising hybrid removal opens the door to the easier fabrication of ultrathick metallic microstructures by UV-LIGA.
关键词： high aspect ratio,ECF micropump,CO2 laser engraving,SU-8 removal,triangular prism & slit electrode pair
更新于2025-09-23 15:22:29
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[Lecture Notes in Computational Vision and Biomechanics] Computer Aided Intervention and Diagnostics in Clinical and Medical Images Volume 31 || A Review on Haze Removal Techniques
摘要： Images captured in outer environment suffer from reduced scene visibility, reduced color contrast, and increased color fading. This may happen due to the presence of haze, fog, smoke, dust and noise present in the outer atmosphere. Haze is formed due to two basic processes, attenuation and air light. Attenuation diminishes the contrast of the image and air light makes the image to be whiter and hence the image captured is unclear. Haze removal or image dehazing is required in real-world weather conditions to obtain a fast and high-quality hazy free image which is used in various ?elds like satellite systems and aircraft systems. The intention of this review paper is to give a brief analysis on different haze removal techniques.
关键词： Haze removal,Image enhancement,Dark channel prior,Genetic algorithm,Filtering
更新于2025-09-23 15:22:29
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Facile preparation of antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic polyvinylidene fluoride membranes for effective removal of rhodamine B
摘要： A simplified strategy for facilely fabricating antifouling graphite carbon nitride/silver phosphate (g-C3N4/Ag3PO4) nanocomposite photocatalytic polyvinylidene fluoride (PVDF) porous membranes was developed for effective removal of rhodamine B (RhB). g-C3N4/Ag3PO4 heterojunction was strongly fixed to the interior of the PVDF membranes via phase inversion method. The membrane structure was analyzed by Fourier transform spectrophotometer (FT-IR). The morphology of the prepared membranes was investigated using scanning electron microscopy (SEM), EDX-mapping and atomic force microscopy (AFM), respectively. All prepared nanocomposite photocatalytic PVDF membranes exhibited a typically porous structure, and g-C3N4/Ag3PO4 nanocomposites were well dispersed inside the membranes. The obtained g-C3N4/Ag3PO4 heterojunction nanoparticle decorated PVDF membrane had a lower water contact angle of 79o and higher porosity of 85% than that of other two control membranes. The nanocomposite photocatalytic PVDF porous membranes had extremely high permeation flux over 1,083 L·m?2·h?1, and could be used for the removal of RhB. The removal efficiency of g-C3N4/Ag3PO4-PVDF membranes towards RhB solution under visible light irradiation reached 97%, higher than that of the pure PVDF membranes (41%) and g-C3N4-PVDF membranes (85%). Remarkably, the flux performance and flux recovery ratio (FRR) of membranes revealed that the g-C3N4/Ag3PO4-PVDF membranes could recover high flux after fouling, which presented better fouling resistance. Furthermore, the fabricated antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic PVDF porous membranes exhibited excellent recyclability. Therefore, it is expected that g-C3N4/Ag3PO4-PVDF membranes could provide an energy-saving strategy for effective removal of organic dyes wastewater and have a great potential for practical wastewater treatment in the future.
关键词： PVDF Membranes,Anti-fouling Properties,g-C3N4/Ag3PO4 Heterojunction,Removal RhB
更新于2025-09-23 15:22:29
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Robust artifact-free high dynamic range imaging of dynamic scenes
摘要： The irradiance range of the real-world scene is often beyond the capability of digital cameras. Therefore, High Dynamic Range (HDR) images can be generated by fusing images with different exposure of the same scene. However, moving objects pose the most severe problem in the HDR imaging, leading to the annoying ghost artifacts in the fused image. In this paper, we present a novel HDR technique to address the moving objects problem. Since the input low dynamic range (LDR) images captured by a camera act as static linear related backgrounds with moving objects during each individual exposures, we formulate the detection of foreground moving objects as a rank minimization problem. Meanwhile, in order to eliminate the image blurring caused by background slightly change of LDR images, we further rectify the background by employing the irradiances alignment. Experiments on image sequences show that the proposed algorithm performs significant gains in synthesized HDR image quality compare to state-of-the-art methods.
关键词： Multi-exposure fusion,High dynamic range imaging,Rank minimization,Motion blur,Optical flow,Ghost removal
更新于2025-09-23 15:22:29
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Robust Noisiness Measure Based Improved Generalized Fuzzy Peer Group for Removal of Mixed Noise From Color Image
摘要： In this letter, a novel method has been proposed to estimate noisiness of a pixel in an image. The proposed noisiness is based on a robust noisiness measure, which is evaluated using noise and edge information of locality of the pixel. Furthermore, this noisiness is used to develop a fuzzy peer group for removing mixed Gaussian and impulse noises from color images. Also, an iterative approach to the proposed method is presented. The proposed approach is then compared with the state-of-the-art algorithms. Results shows that the proposed method outperform existing algorithms significantly.
关键词： fuzzy peer group,robust noisiness measure,Mixed noise removal
更新于2025-09-23 15:22:29
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Modeling and multiresponse optimization of cutting parameters in SPDT of a rigid contact lens polymer using RSM and desirability function
摘要： Amidst different conventional contact lens manufacturing techniques, single-point diamond turning (SPDT) is one of the recently developed ultra-high precision machining techniques employed in the fabrication of advanced contact lenses due to its capability of producing high optical surfaces of complex shapes and nanometric accuracy. SPDT is regarded as an effective process for the generation of high-quality functional surfaces in optical industries. However, despite advances in the ultra-high precision machining, it is not always easy to achieve a high-quality surface finish with maximum productivity. Machining parameters, namely cutting speed, feed rate, and depth of cut, play the lead role in determining the machine economics and quality of machining. The present study focuses on the determination of the optimum cutting conditions leading to minimum surface roughness as well as electrostatic charge and maximum productivity, in SPDT of the polymethyl methacrylate (PMMA) contact lens polymer using monocrystalline diamond cutting tool. The optimization is based on the response surface methodology (RSM) together with the desirability function approach. In addition, a mathematical model is developed for surface roughness (Ra), electrostatic charge (ESC), and material removal rate (MRR) using RSM regression analysis for a rigid contact lens polymer by the Design-Expert software. RSM allowed the optimization of the cutting conditions for minimal surface roughness, electrostatic charge, and maximal material removal rate which provides an effective knowledge base for process parameters, to make its enhancement of process performance in SPDT of contact lens polymer.
关键词： Electrostatic charge,Response surface methodology,Material removal rate,Surface roughness and optimization,PMMA contact lens polymer,Single-point diamond turning
更新于2025-09-23 15:22:29
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Removal of rain video based on temporal intensity and chromatic constraint of raindrops
摘要： An improved algorithm of frame time difference is proposed and applied to raindrops removal of video image.This paper analyzes the temporal intensity waveform and chromatic constraint properties of raindrops, and the method is optimized by these two properties. We make use of the difference between rain and non-rain moving objects in the pixels’ intensity changes, which realized a broad classification between the rain and non-rain moving object pixel. The candidate raindrops pixels are optimized in combination with the chromatic constraint property. The experimental results show that the proposed algorithm has a better effect of rainy day in video image restoration than Garg’s, and it is simple and effective. The algorithm has a strong applicability, and it can be further used for many applications, such as air pollution control, management, outdoor surveillance, remote sensing and intelligent vehicles.
关键词： Chromatic constraint,Temporal intensity waveform,Raindrops detection,Raindrops removal
更新于2025-09-23 15:21:21
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Efficiency of sequential UV/H2O2 and biofilm process for the treatment of secondary effluent
摘要： In response to the shortage of water resources, multiple processes have been applied to turn wastewater secondary effluent (SE) into potable water. However, trace organic contaminants (TOrCs) and high concentrations of organic matter contained in SE pose a significant challenge to the reclamation. In this manuscript, combined UV-based and biofilm processes were used to treat the SE spiked with ibuprofen (IBU) and clofibric acid (CA). The efficiency of these sequential treatments was characterized in terms of changes in dissolved organic carbon (DOC), absorbance at 254 nm (A254), fluorescence excitation-emission matrix (FEEM), the concentration of IBU and CA, and molecular weight of SE. Parallel factor (PARAFAC) was applied as the analysis method for FEEM of the samples and two fluorescent components were successfully identified: humic-like substances (C1) and protein-like matter (C2). Large reductions in A254, C1, C2, IBU, and CA were observed during the UV-based processes, especially with the addition of H2O2. Nearly 50% of A254, 80% of the component C1 were decreased and almost complete removal of the component C2 and TOrCs was achieved by UV/2.0 mM H2O2 after 90-min treatment. During the oxidation processes, the formation of lower molecular weight (LMW) compounds was detected, and the biodegradability of the organic matters was greatly increased. Although no significant DOC reduction was obtained in UV-based processes, an obvious further DOC reduction (30~60%) was achieved by biofilm treatment following UV-based processes, especially after UV/H2O2 treatments. In the meantime, large amounts of LMW were removed in the biofilm treatment process. This manuscript provides an effective advanced treatment of SE for the removal of DOC and TOrCs, facilitating the wastewater reclamation.
关键词： Trace organic contaminants,Removal,Biofilm,Secondary effluent,Dissolved organic carbon,UV/H2O2
更新于2025-09-23 15:21:21