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- 2018
- imgae sensor
- internet of things
- drone
- visible light ID
- Signal-to-Noise Ratio (SNR)
- Infinite Gain Multiple Feedback (IGMF)
- Visible Light Communications (VLC)
- LED
- Trans-Impedance Amplifier (TIA)
- Optoelectronic Information Science and Engineering
- Tohoku University
- University of Northumbria
- University of Huddersfield
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Multiple Access Design for Ultra-Dense VLC Networks: Orthogonal v.s. Non-Orthogonal
摘要： Small cell aided ultra-dense networks (UDN) constitute an efficient solution to the ever-increasing thirst for more data. Thanks to the vast untapped high-frequency spectrum of visible light, visible light communications (VLC) is a natural candidate for UDN. In this paper, layered asymmetrically clipped optical OFDM (LACO-OFDM) aided ultra-dense VLC (UD-VLC) is investigated in terms of its user-association, multiple access (MA) and resource allocation. To handle the severe inter-cell interference (ICI) amongst the densely-deployed access points (AP), we propose a novel overlapped clustering technique relying on a hybrid non-orthogonal MA (NOMA) and orthogonal MA (OMA) scheme for enhancing the performance, with the aid of our dynamic resource allocation conceived. Our simulations show that the proposed LACO-OFDM aided UD-VLC using our hybrid MA scheme is more robust against the ICI, at a price of modestly decreasing the sum-throughput.
关键词： visible light communications (VLC),resource allocation,non-orthogonal multiple access (NOMA),Ultra-dense network (UDN),multiple access (MA)
更新于2025-09-09 09:28:46
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Noise Analysis and Modeling in Visible Light Communication Using Allan Variance
摘要： Visible Light Communication (VLC) is a rising communication technology which uses Light-Emitting Diode (LED) luminaries for high-speed data transferring; however, the optical signal is usually degraded by the noise in the practical VLC system. In this article, Allan Variance is introduced for noise analysis and modeling in VLC for the first time, which provides an efficient method to measure different kinds of noise in the VLC systems. By applying Allan variance to analyze the signals collected from the real-world environment, both white noise and random walk are observed in the VLC systems. The observed white noise and random walk are also modeled by using the Allan variance. The noise analysis and modeling based on Allan variance provide a method to improve the performance of VLC.
关键词： Visible Light Communication (VLC),random walk,white noise,Allan Variance,time-correlated noise,photodiode
更新于2025-09-09 09:28:46
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Substituent Effect on Metastable‐State Photoacids: Design, Synthesis and Evaluation of their Photochemical Properties
摘要： Recently, metastable-state photoacids have been widely used to control proton transfer in numerous chemical and biological processes as well as applications with visible light. Generally, substituent groups have great influence on photochemical properties of molecules, which will further affect their applications. Yet, substituent effect on the metastable-state photoacid has not been studied systematically. In this work, sixteen metastable-state photoacid derivatives were designed and synthesized based on their substituents involving a large range of σ-π electron-donor-acceptor capability. Substituent effects main on their color display (or maximum absorption peak(s)), solubility, pKa(s), dark-/photo-acidity, photosensitivity and relaxation kinetic(s) were investigated in detail. This study will be conducive to targetedly design and synthesize promising photoacids as well as to apply their photo-controlled proton-release processes in functional materials/devices.
关键词： visible-light-response,metastable-state photoacid,pH photocontrol,substituent effect,chemical dynamics
更新于2025-09-09 09:28:46
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Visible light accelerates the ultraviolet A-induced degradation of eumelanin and pheomelanin
摘要： Exposure to excess ultraviolet (UV) A radiation induces the degradation/modification of both eumelanin and pheomelanin that may be deleterious to pigmented tissues. Although the spectral distribution of solar energy comprises nearly half of visible light (VL), few studies have been conducted to examine the role of VL in the photodegradation of both types of melanin, either VL alone or in combination with UVA. In this study, we examined the effects of physiological doses of VL (150 to 300 J/cm2) alone or in combination with a physiological dose of UVA (20 J/cm2) in normal human epidermal melanocytes. The degradation/modification of melanin structures were evaluated by our chemical degradation – HPLC methods. The results show that VL accelerates UVA-induced changes in the structural features of both eumelanin and pheomelanin, although VL or UVA alone induced only minor changes in melanin structure. The differential spectral method provides support for the additive effects of VL.
关键词： visible light,eumelanin,photodegradation,pheomelanin,ultraviolet A
更新于2025-09-09 09:28:46
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Effective detection by fusing visible and infrared images of targets for Unmanned Surface Vehicles
摘要： The research progress for Unmanned Surface Vehicle (USV) is of great significance to human off-shore operations. Target detection is the foundation for USV applications. Ocean wave, frog, and illumination are the most important factors that affect exactness of target detection through visible and infrared images. This paper proposes an algorithm for weighted averaging fusion of visible/infrared images. Firstly, the visible light/infrared devices are required to collect the target surrounding information, perform feature analysis, and complete the anti-fog and de-noising preprocessing. These operations aim at improving the accuracy of image segmentation. Secondly, feature extractions of the visible and infrared target images are performed, respectively, and the recognition of the target image is further completed. Finally, image fusion is performed by weighted averaging of the targets detected by visible light and infrared images. The fusion uses a matching matrix to represent the similarity of the two images. When the two images are very similar, the image is fused by weighting pixels, which effectively improves the accuracy of the detection. Lots of simulations were conducted on MATLAB 2015a with a personal computer, and the results verified the success rate of target detection and recognition.
关键词： fusion,Multi-scale fractal,target detection,visible image,infrared image
更新于2025-09-09 09:28:46
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[ACM Press the 1st International Workshop - New Delhi, India (2018.10.29-2018.10.29)] Proceedings of the 1st International Workshop on Communication and Computing in Connected Vehicles and Platooning - C3VP '18 - On Feasibility of VLC Based Car-to-Car Communication Under Solar Irradiance and Fog Conditions
摘要： This paper investigates the impact of solar irradiance and fog condition on visible light communication (VLC) based car-to car (C2C) communication for two capital cities, New Delhi and London. The bit error rate (BER) variation over a day has been compared for both the cities for the month of March, June and December. It has been shown that for a given BER threshold performance, the impact of solar irradiance is more pronounced in month of June especially at New Delhi when solar irradiance reaches its peak. It has also been shown that in month of December, fog is one of the most significant climatic factors that greatly influences the VLC based C2C communication in terms of atmospheric attenuation. This paper also establishes the relationship for the minimum safety distance required between cars based on two-second rule, car speed and angle between cars. The minimum safety distance which would be required to avoid any rear-end collision especially during light or dense fog in the month of December has also been compared for New Delhi and London.
关键词： safety distance,fog conditions,solar irradiance,car-to-car communication,visible light communication,bit error rate
更新于2025-09-09 09:28:46
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Degradation of Rhodamine B Under Visible-Light by Cu-Doped ZnAl Layered Double Hydroxide
摘要： The Cu-doped ZnAl layered double hydroxides (LDH) were papered by coprecipitation. The prepared samples were characterized by mutiple techniques including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse-re?ectance spectroscopy (UV-vis DRS). The doping of Cu2+ into the LDH sheets results in formation of the distorted CuO6 octahedrons which contribute for the excitation of electrons under visible light. The doped Cu2+ also serves as photo-generated charges separator and improves the visible-light-driven photocatalytic activity of ZnAl LDH. A degradation mechanism based on the hydroxyl radical as the active species was proposed.
关键词： RhB Degradation,Visible Light,Copper-Doping,Layered Double Hydroxides
更新于2025-09-09 09:28:46
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Enhanced Photocatalytic Activity of B, N-Codoped TiO <sub/>2</sub> by a New Molten Nitrate Process
摘要： B, N-codoped titania mesoporous crystals were prepared by the sol–gel method followed by a molten nitrate process to modify the sample morphology. The composition, morphology and microstructure of the obtained samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Fourier Transform Infrared spectroscopy (FTIR) revealed weak complex vibrations between the Ti–O oxide species and the unsaturated sites (Ti3+) through the incorporation of hydroxyl groups, which was not observed in the bulk titania (B–N–TiO2). The photocatalytic reactivity of boron-nitrogen codoped TiO2 was examined for the removal of methylene blue (MB) under visible light irradiation. The nitrates treated B-doped TiO2 exhibited better photocatalytic activity for dye degradation than that of B-doped TiO2 and nitrates treated TiO2. The best performance was obtained in the sample treated at a calcination temperature of 550 °C.
关键词： Photocatalysis,Visible Light,Nitrate,Boron Doped Titanium Dioxide
更新于2025-09-09 09:28:46
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A Review on BiOX (X= Cl, Br and I) Nano-/Microstructures for Their Photocatalytic Applications
摘要： In the recent past, bismuth oxyhalides (BiOX) have been widely used for the photocatalytic degradation of the organic pollutants and other environmental remediation because of their higher stability, economic viability, nontoxicity and effective charge separation. We begin with the review of the different approaches adopted so far for BiOX (X = Cl, Br, and I) synthesis and a study of their photocatalytic performances under UV and visible light towards the various organic as well as inorganic pollutants. Later on, a study on further enhancement of the ef?ciency of BiOX under UV and visible light irradiation using recent advancements would be presented. The new approaches involve controlled morphology by forming composite and hybrid materials with other semiconductors and also doping with other metals and nonmetals that would undoubtedly be bene?cial in the interfacial charge transfer and ef?cient inhibition of the photo-generated species. Herein, we would also exploit the recent developments in the research strategies for enhancing photocatalytic activity of BiOX.
关键词： Pollutants,Photocatalysts,Functionalization,Stability,Bismuth Oxyhalides,Heterostructures,Photogenerated Species,Environmental Remediation,Composites,Photodegradation,Visible Light
更新于2025-09-09 09:28:46
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Shape Tailored TiO <sub/>2</sub> Nanostructures and Their Hybrids for Advanced Energy and Environmental Applications: A Review
摘要： Shape tailored TiO2 nanostructures with various dimensionality (zero to three dimension) have unique physicochemical and functional properties that facilitates its efficient energy and environment applications, e.g., solar light driven photocatalytic hydrogen generation and decontamination of organic/inorganic toxic pollutants, CO2 reduction into the hydrocarbon fuels, solar cells, supercapacitors and lithium-ion batteries etc. However, the wide band gap nature and the fast recombination of the photogenerated charge carriers in TiO2 usually limit its overall performance under solar light illumination. In this review, we present a state of the art on the fabrication techniques of shape tailored TiO2 nanostructures and the strategies employed to make the system catalytically more efficient. Though shape tailored TiO2 nanostructures with large specific surface area and highly energetic (001) facet exposed TiO2 nanostructures (2D and 3D) can enhance the photocatalytic efficiency to a reasonable extent, further surface engineering is needed for the modification of the electronic band arrangement, visible light sensitization and efficient charge separation. Herein, TiO2 heterostructures (HSs) with metal/non-metal doping, surface fluorination, plasmonic noble metal nanoparticles (NPs) and coupling with the narrow band gap suitable semiconductor (type-II) are discussed in details covering from zero dimensional to three dimensional heterostructures. The synthesis strategies, charge transfer mechanism and their participation in the photocatalysis are elaborated. Though one dimensional TiO2 HSs have been widely studied, we present the recent development of critical surface engineering strategies of two and three dimensional systems, which give rise to the excellent properties including the enlargement of surface area, light absorption capability and efficient separation of electrons/holes resulting in the superior performance in advanced applications. Based on recent breakthroughs in the field, future directions and outlook of the field are presented at the end.
关键词： Type-II Heterostructure,2D TiO2,3D TiO2,Shape Tailored TiO2 Nanostructures,1D TiO2,Visible Light Photocatalysis,Hydrogen Production,0D TiO2,Plasmonic Heterostructure
更新于2025-09-09 09:28:46