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- 2018
- imgae sensor
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- Signal-to-Noise Ratio (SNR)
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Ag/Fe3O4/CuO/ZnO incorporated NGP materials: Visible light driven photocatalysts for the degradation of water pollutants
摘要： Ag/Fe3O4/CuO/ZnO/nanographene platelets (NGP) composites with different NGP loadings were synthesized in the present study using a simple hydrothermal method. The photocatalytic activities of the prepared Ag/Fe3O4/CuO/ZnO/NGP composites were then studied for their ability to degrade different kinds of dyes in aqueous solutions under visible light irradiation. The X-ray diffraction (XRD) results indicate a face-centered cubic structure for Ag, a cubical spinel structure for Fe3O4, a monoclinic structure for CuO, and a hexagonal wurtzite structure for ZnO. Furthermore, a graphite-like structure could be detected for NGP. The thermal stability of the samples was evaluated by TGA; the results further confirm the good agreement between the actual and theoretical (5, 10, and 15 wt.%) weight loadings of NGP in the samples. Ultraviolet–visible (UV–Vis) absorbance spectroscopy was used to analyze the optical properties of the prepared samples; a surface plasmon resonance (SPR) phenomenon could be detected around ~ 440 nm and after the addition of NGP, the absorption band shifted to the visible light region. The ternary Ag/ Fe3O4/CuO/ZnO/NGP composites exhibit a significantly enhanced photocatalytic activity than either Ag/ Fe3O4/CuO/ZnO or Fe3O4/CuO/ZnO in degrading a methylene blue (MB) dye in an aqueous solution. When the NGP loading was 10 wt.%, the composites displayed the highest photocatalytic activity. The Ag/ Fe3O4/CuO/ZnO/NGP could efficiently degrade a variety of organic dyes, such as MB, Congo red (CR), and methyl orange (MO) under visible light irradiation. The species active in the degradation process were found to be the holes. More importantly, Ag/ Fe3O4/CuO/ZnO/NGP composites demonstrated good stability and reusability in repetitive photocatalytic activity processes.
关键词： visible photocatalysis,NGP,Fe3O4,Ag,ZnO
更新于2025-09-23 15:23:52
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Facile synthesis of N/B double-doped Mn <sub/>2</sub> O <sub/>3</sub> and WO <sub/>3</sub> nanoparticles for dye degradation under visible light
摘要： In the present work, Nitrogen-doped and Nitrogen-Boron double doped manganese oxide (Mn2O3) and tungsten oxide (WO3) nanoparticles were synthesized using precipitation-hydrothermal method for methylene blue degradation under visible light. Materials were characterized using X-ray diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and UV-Vis spectroscopy. Results showed that N and B were successfully incorporated into the crystal lattices of Mn2O3 and WO3. XRD showed that WO3 was crystallized in the form of a monoclinic lattice, while cubic Mn2O3 was produced in the cubic form. The crystallite size was found to be decreased due to the substitution of N and B elements which reveals their roles to accelerate the crystal nucleation rate resulting in the decreased size. On the other hand, single and double doping has successfully narrowed the bandgaps of the as-synthesised metal oxide photocatalysts resulting in better absorption in the visible light. Bandgaps obtained were as follows: 3.02, 2.50, 1.73 and 1.77 eV for N-WO3 N/B-WO3, N-Mn2O3 and N/B-Mn2O3 respectively. Photocatalytic experiments showed that all as-synthesised materials exhibited a photocatalytic efficiency under visible light ≥420 nm. The degradation efficiency of MB was in the following order: N-B-co-doped metal oxides > N-doped metal oxides > metal oxides. The presence of scavenger molecules such as isopropanol (IPA), EDTA-2Na and benzoquinone inhibited MB degradation. Finally, the results showed that these materials can be reused several times without a notable decrease in efficiency.
关键词： Photocatalytic degradation,Visible light,Double-doping,Metal oxides
更新于2025-09-23 15:23:52
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Construction of Strontium Titanate/Binary Metal Sulfide Heterojunction Photocatalysts for Enhanced Visible-Light-Driven Photocatalytic Activity
摘要： A novel strontium titanate/binary metal sulfide (SrTiO3/SnCoS4) heterostructure was synthesized by a simple two-step hydrothermal method. The visible-light-driven photocatalytic performance of SrTiO3/SnCoS4 composites was evaluated in the degradation of methyl orange (MO) under visible light irradiation. The photocatalytic performance of SrTiO3/SnCoS4-5% is much higher than that of pure SrTiO3, SnCoS4, SrTiO3/SnS2 and SrTiO3/CoS2. The SrTiO3/SnCoS4 composite material with 5 wt.% of SnCoS4 showed the highest photocatalytic efficiency for MO degradation, and the degradation rate could reach 95% after 140 min irradiation time. The enhanced photocatalytic activity was ascribed to not only the improvement of visible light absorption efficiency, but also the construction of a heterostructure which make it possible to effectively separate photoexcited electrons and holes in the two-phase interface.
关键词： visible-light-driven,SnCoS4,heterojunction,degradation,SrTiO3
更新于2025-09-23 15:23:52
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The LXe calorimeter and the pixelated timing counter in the MEG II experiment
摘要： The MEG experiment is to look for a lepton flavor violating μ + → e+γ decay with an unprecedented sensitivity, and we set an upper limit of the branching ratio for this decay, 5.7 × 10?13 at 90% C.L. in 2013 which is a twenty times more stringent limit than the previous experiment, MEGA. Since the sensitivity improvement was limited by the accidental background, we have considered the major detector upgrade. A proposal was submitted to PSI committee, and was approved in 2013, which aims at a sensitivity enhancement of one order of magnitude compared with the current MEG experiment. Here mainly two components of the MEG detector will be introduced, a γ-ray calorimeter with 900 L of liquid xenon (LXe), and a pixelated timing counter. The LXe detector will be improved by increasing the granularity at the incident face, by replacing the current PMTs with a larger number of smaller photosensors (MPPC) and optimizing the photosensor layout also on the lateral faces. A new highly segmented, fast timing counter array will replace the old system to allow improved timing resolution capabilities.
关键词： visible and IR photons (solid-state),HPG,Large detector systems for particle and astroparticle physics,Photon detectors for UV,CZT,Gamma detectors (scintillators,HgI etc),Timing detectors
更新于2025-09-23 15:23:52
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Constructing 3D sub-micrometer CoO octahedrons packed with layered MoS2 shell for boosting photocatalytic overall water splitting activity
摘要： A 3D architectures of CoO@MoS2 composite photocatalyst was prepared by coating MoS2 onto the (1 1 1) facts of sub-micrometer CoO octahedrons via a facile solvothermal method. The CoO@MoS2 composites show a significantly improved photocatalytic activity for overall water splitting. At an optimal ratio of 3 wt% MoS2, CoO@MoS2-3% composite can split pure water with the stoichiometric ratio production of H2 and O2 under visible light irradiation, meanwhile, presents the highest H2 production evolution (1.07 μmol/h), which is almost four times than that of pure CoO (0.26 μmol/h). Moreover, the CoO@MoS2 composite still remains good stability after three successive cyclings (over 72 h). The enhanced photocatalytic activity and stability can be attributed that the layered MoS2 shell not only promoted the photo-induced charge transfer at the interface of CoO due to the sufficient contact area between CoO and MoS2, but also protected the exposed the (1 1 1) facts of CoO from devastation. Our work offers more insights into the development of a simple synthesis of well-shaped 3D-based composite photocatalysts towards the energy- and environmental-related applications.
关键词： CoO octahedrons,MoS2,Overall water splitting,Core-shell,Visible light
更新于2025-09-23 15:23:52
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Layered Adaptive Collaborative Constellation for MIMO Visible Light Communication
摘要： In this paper, we propose a novel technique to effectively design a channel adaptive collaborative constellation called the layered adaptive collaborative constellation (LACC) for multiple-input multiple-output visible light communications. Recently, a channel-adaptive space-collaborative constellation (CASCC) that designs the constellation with the consideration of channel into the model to improve the receiver mobility and enhance the error performance. However, this scheme only considers into optimization four constellation points that form a diamond shape in the receiver space. Our proposed scheme effectively exploits the layered structure of collaborative constellation and overcomes the aforementioned drawbacks of CASCC. Furthermore, an improved low-complexity maximum likelihood (ML)-based detector is derived. Simulation results show that the LACC can achieve some performance gain, compared with previous constellation design schemes for different scenarios, especially really high-correlation channels and under imperfect channel state information. Moreover, the proposed detector drastically reduces computational complexity while maintaining the same performance as a traditional ML detector.
关键词： maximum likelihood (ML) detection,multiple-input multiple-output (MIMO),Visible light communications (VLC),space collaborative constellation
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Iasi, Romania (2018.10.18-2018.10.19)] 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Analysis of Light Design in the Lighting Laboratory of the Riga Technical University
摘要： Given the fact that it is required to increase the efficiency of energy consumption in the premises, it is necessary to develop an effective lighting design that can be used both in old buildings and in new projects. To achieve a lower overall energy consumption by a building without sacrificing the quality of lighting, effective lighting modeling is needed, which allows to obtain reliable results for models as close as possible to real life, taking into account energy-saving lighting devices, integration of daylight in order to reduce energy consumption and maintenance costs, etc. The research evaluates possibility to measure luminance of light sources and detect sources of glare, using ordinary digital single-lens reflex camera (DSLR) and image editing software. Methodology and workflow is presented. The results then are discussed and ways to improve the accuracy of the measurements are highlighted.
关键词： visible spectrum,light measurements,digital camera,fluctuations,Dialux,glare
更新于2025-09-23 15:22:29
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Nondestructive egg freshness assessment from the equatorial and blunt region based on visible near infrared spectroscopy
摘要： This research was to study which orientation was better for freshness prediction of the white-shelled eggs using visible near infrared spectroscopy. The transmission spectra were acquired in the equatorial region and at the blunt end of the eggs. After each spectral measurement, the Haugh unit, yolk index, and albumen pH as the freshness parameters were simultaneously measured using traditional destructive methods. Pretreatment methods containing Savitzky-Golay smoothing, multiplicative scatter correction, the standard normal variate, the first derivative and the second derivative were used. A partial least squares regression was developed to predict the Haugh unit, yolk index, and albumen pH. The best correlation coefficients of prediction were obtained from the equatorial region, and were 0.881, 0.855, and 0.888 for the Haugh unit, yolk index and albumen pH, respectively. And root mean square errors in the prediction set were 7.720, 0.034, and 0.147 for the Haugh unit, yolk index and albumen pH, respectively. The results illustrated that the equatorial region showed better ability than the blunt end to predict freshness of the white-shelled eggs.
关键词： nondestructive,visible near infrared spectroscopy,orientation,freshness,Egg
更新于2025-09-23 15:22:29
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Distance-Range-Oriented Constellation Design for VLC-SCMA Downlink with Signal-dependent Noise
摘要： In this paper, the constellation design for a sparse code multiple access (SCMA) based visible light communication (VLC) downlink is studied. The noise at the receiving avalanche photodiode (APD) is dependent on the signal intensity, and the associated design problems are typically intractable. We point out that for such a system both the minimum Euclidean distance (MED) and Rotated-MED based methods are not the optimal optimization objective, and propose a distance-range-oriented (DRO) modulation, where a linear combination of the minimum and maximum Euclidean distance is considered. We observe in the simulation results that the proposed DRO-based scheme outperform the MED and Rotated-MED based ones across a wide range of signal and noise levels.
关键词： distance range,signal-dependent noise,Constellation design,SCMA,visible light communication
更新于2025-09-23 15:22:29
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Design of PAM-DMT-based Hybrid Optical OFDM for Visible Light Communications
摘要： In this letter, a pulse-amplitude-modulated based hybrid optical orthogonal frequency division multiplexing (PHO-OFDM) scheme is proposed. We use the high order quadrature-amplitude-modulation to replace the one-dimensional pulse-amplitude-modulated on the even subcarriers for compensating the data capacity weakness of the conventional pulse amplitude modulated discrete multitone (PAM-DMT). The combined time-domain PHO-OFDM signal has a larger amplitude range than the original PAM-DMT but with a reduced peak-to-average power ratio (PAPR). Besides that, a flexible power allocation method is introduced to the proposed PHO-OFDM systems to fully exploit the whole dynamic range of LEDs. The simulation results show that, under the same average bit rate, the proposed PHO-OFDM scheme has a better bit error rate performance compared with the conventional PAM-DMT scheme, thus demonstrating its application potential in visible light communications.
关键词： visible light communications (VLC),pulse-amplitude-modulated discrete multitone (PAM-DMT),optical orthogonal frequency division multiplexing (O-OFDM)
更新于2025-09-23 15:22:29