- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Synergetic utilization of photoabsorption and surface facet in crystalline/amorphous contacted BiOCl-Bi2S3 composite for photocatalytic degradation
摘要： Photoabsorption and surface property of semiconductor are two key factors to determine its photocatalytic performance. In this work, BiOCl-Bi2S3 composites composed of Bi2S3 nanoparticles bonded on BiOCl nanoplates enclosed with {001} and {110} crystal facets were synthesized through an in-situ ion exchange method at room temperature. The transformed Bi2S3 made BiOCl-Bi2S3 composites efficient visible light absorption, ensuring the quantity of photoinduced carriers as well as intimate crystalline-amorphous contact interface to benefit the separation of photoinduced carriers. Moreover, BiOCl nanoplates enclosed with {001} and {110} crystal facets can convenient transfer carriers to {001} crystal facets. The photocatalytic performance of BiOCl-Bi2S3 composites was evaluated by the methylene blue photodegradation under visible light irradiation and the results indicate that BiOCl-Bi2S3 composites have good photocatalytic ability due to enhanced light absorption, efficient separation and transfer of carriers. Based on the active species trapping experiments, transient photocurrents, electrochemical impedance spectroscopy and energy band structure, a possible photocatalytic mechanism of methylene blue over the BiOCl-Bi2S3 composites was proposed.
关键词： Surface property,Visible light,BiOCl-Bi2S3,Contact interface,Photocatalytic mechanism,Crystal facet
更新于2025-09-23 15:22:29
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Hybrid TDOA/RSS based localization for visible light systems
摘要： In a visible light positioning (VLP) system, a receiver can estimate its location based on signals transmitted by light emitting diodes (LEDs). In this manuscript, we investigate a quasi-synchronous VLP system, in which the LED transmitters are synchronous among themselves but are not synchronized with the receiver. In quasi-synchronous VLP systems, position estimation can be performed by utilizing time difference of arrival (TDOA) information together with channel attenuation information, leading to a hybrid localization system. To specify accuracy limits for quasi-synchronous VLP systems, the Cramér–Rao lower bound (CRLB) on position estimation is derived in a generic three-dimensional scenario. Then, a direct positioning approach is adopted to obtain the maximum likelihood (ML) position estimator based directly on received signals from LED transmitters. In addition, a two-step position estimator is proposed, where TDOA and received signal strength (RSS) estimates are obtained in the first step and the position estimation is performed, based on the TDOA and RSS estimates, in the second step. The performance of the two-step positioning technique is shown to converge to that of direct positioning at high signal-to-noise ratios based on asymptotic properties of ML estimation. Finally, CRLBs and performance of the proposed positioning techniques are investigated through simulations.
关键词： Received signal strength (RSS),Estimation,Visible light,Localization,Time difference of arrival (TDOA)
更新于2025-09-23 15:22:29
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Synthesis of silver phosphate/sillenite bismuth ferrite/graphene oxide nanocomposite and its enhanced visible light photocatalytic mechanism
摘要： In the present work, silver phosphate/sillenite bismuth ferrite/graphene oxide (Ag3PO4/Bi25FeO40/GO) nanocomposite has been successfully fabricated via hydrothermal strategy and ultrasound precipitation treatment. Afterwards, physicochemical properties of as-obtained composite were studied through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), Brunauer-Emmett-Teller (BET) surface areas, vibrating sample magnetometer(VSM) measurements. Meanwhile, Linear sweep voltammetry (LSV), Mott-Schottky (M-S), Transient photocurrent-curves and electrochemical impedance spectroscopy (EIS) measurements were measured to investigate the photoelectrochemical properties. Besides, the degradation efficiency of Rhodamine B was as the evaluation of PC efficiency, which could reach 96.9% after 75min illumination. The results indicated that spherical Ag3PO4 and Bi25FeO40 crystallographic particles were integrated with GO and the enhanced PC performance can be attributed to significantly visible light absorbance and charge separation efficiency. Furthermore, to distinguish the contribution of reactive species including ?O2?, ?OH, H2O2, h+ and e?, several scavenger experiments have been conducted. Noticeable, the Ag3PO4/Bi25FeO40/GO nanocomposite has magnetic because of the integration with Bi25FeO40. Eventually, the possible photocatalytic performance mechanism of Ag3PO4/Bi25FeO40/GO was proposed.
关键词： Ag3PO4/Bi25FeO40/GO,Visible light photocatalysis,Photocatalytic performance mechanism,Magnetic nanocomposite
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Electrical Engineering and Computer Science (ICECOS) - PANGKAL PINANG, Indonesia (2018.10.2-2018.10.4)] 2018 International Conference on Electrical Engineering and Computer Science (ICECOS) - Design and Implementation of Analog Transceiver Circuit for Patient Monitoring System based on OWC
摘要： In this paper, we present the design and implementation of analog front-end (AFE) module for patient monitoring system based on optical wireless communication (OWC). The communication link uses visible light as a downlink and IR as an uplink communication. The wireless patient monitoring system consists of two parts: host or coordinator and client or patient device. On the patient device part, we designed the PCB with a shield configuration so the AFE module can be connected directly to GPIO’s microcontroller unit (MCU) without any cable. Moreover, the AFE module is attempted to have a similar size with the MCU. Hence, the patient device has a small-size, minimum of wires, wearable, and low-complexity. The AFE receiver output is a digital waveform. Therefore, it is compatible with On-off Keying (OOK) modulation. The AFE module can be switched digitally up to 25 KHz of optical frequency for visible light downlink and 1500 Hz optical frequency for IR uplink. The optical link distance can reach up to 2 meters with 0o of reception angle.
关键词： Visible light communication,Wearable patient monitoring,IR communication,Optical Wireless Communication (OWC),Analog Front-End
更新于2025-09-23 15:22:29
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[ACM Press the 16th ACM Conference - Shenzhen, China (2018.11.04-2018.11.07)] Proceedings of the 16th ACM Conference on Embedded Networked Sensor Systems - SenSys '18 - Selective Visible Light Communication for Multiple Video Cameras using a Single Light Source
摘要： In this paper, we propose a selective visible light communication method using a single light source and multiple video cameras by using their differences in reception sensitivity between carrier waves composed of OFDM signals. In our evaluation experiments, the transmitted signals were composed of 50th, 75th, 78th, and 80th order carrier waves encoding symbols modulated by 4, 8, and 16 PSK. The exposure time ratio for each camera was set to different values so that symbols encoded in one of the carrier waves could be decoded successfully, but erroneously in the other waves. The selectivity of individual carrier waves as theoretically derived was confirmed through the experimental results.
关键词： rolling shutter,Visible light communication,selective communication
更新于2025-09-23 15:22:29
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Multiple Access With Polarity Division Sparse Code for Visible Light Communication
摘要： The increasing demand of mobile internet and Internet of Things poses challenging requirements for indoor wireless communication. Visible light communication (VLC) is a promising technology to alleviate the growing traffic problem. In addition, nonlinear distortion of light emitting diodes (LEDs) results in a poor link quality. In this paper, we propose multiple access with polarity division sparse code (PDSC) for VLC, which is based on nonorthogonal multiple access and spatial characteristic of LEDs. The experimental results indicate that the PDSC significantly enhances capacity and spectral efficiency of VLC network compared with orthogonal frequency division multiple access. We also demonstrate that the PDSC can optimize the problem of nonlinear distortion with polarity division. The experimental results reveal that PDSC is a promising multiple access scheme for the indoor VLC networks.
关键词： Nonorthogonal multiple access,visible light communication,PDSC,nonlinear distortion optimization
更新于2025-09-23 15:22:29
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Generalized Likelihood Block Detection for SPAD-based Underwater VLC System
摘要： In the underwater visible light communication (VLC) system, the single photon avalanche diode (SPAD) can expand communication distance. However, the output signals from practical SPADs under dead time limit are not Poisson distributed. In this paper, the generalized likelihood block detection (GLBD) receiver is developed for practical SPAD-based underwater VLC system with on-off keying (OOK) modulation. The proposed receiver can detect the data sequence without any prior knowledge of the channel and the background radiation. Correspondingly, a fast search algorithm for GLBD receiver is also proposed. In addition, a block coding scheme is utilized to solve the error floor problem. Simulation results show that the bit error rate (BER) performance of the proposed receiver is closer to the BER low bound compared to the existing receiver. Moreover, the fast search algorithm reduces the computational complexity without any performance loss.
关键词： Underwater visible light communication,photon counting,blind detection
更新于2025-09-23 15:22:29
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The Optical Barcode Detection and Recognition Method Based on Visible Light Communication Using Machine Learning
摘要： Visible light communication (VLC) has developed rapidly in recent years. VLC has the advantages of high confidentiality, low cost, etc. It could be an effective way to connect online to offline (O2O). In this paper, an RGB-LED-ID detection and recognition method based on VLC using machine learning is proposed. Different from traditional encoding and decoding VLC, we develop a new VLC system with a form of modulation and recognition. We create different features for different LEDs to make it an Optical Barcode (OBC) based on a Complementary Metal-Oxide-Semiconductor (CMOS) senor and a pulse-width modulation (PWM) method. The features are extracted using image processing and then support vector machine (SVM) and artificial neural networks (ANN) are introduced into the scheme, which are employed as a classifier. The experimental results show that the proposed method can provide a huge number of unique LED-IDs with a high LED-ID recognition rate and its performance in dark and distant conditions is significantly better than traditional Quick Response (QR) codes. This is the first time the VLC is used in the field of Internet of Things (IoT) and it is an innovative application of RGB-LED to create features. Furthermore, with the development of camera technology, the number of unique LED-IDs and the maximum identifiable distance would increase. Therefore, this scheme can be used as an effective complement to QR codes in the future.
关键词： CMOS image sensor,machine learning,image processing,RGB-LED,visible light communication (VLC)
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 10th Latin-American Conference on Communications (LATINCOM) - Guadalajara, Jalisco, Mexico (2018.11.14-2018.11.16)] 2018 IEEE 10th Latin-American Conference on Communications (LATINCOM) - A Comparative Analysis of DSRC and VLC for Video Dissemination in Platoon of Vehicles
摘要： A platoon of vehicles is composed of vehicles moving at a fixed distance and speed, this offers to the driver a comfortable car trip and release him from the stressful driving task. In addition, platooning schemes could also be used to improve the delivery of videos about entertainment, such as movies and news, to increase the user experience. However, such platoon-based services require an efficient Vehicle-to-Vehicle (V2V) communications via Dedicated Short Range Communication (DSRC) and Visible Light Communication (VLC). This paper presents a comparative simulation study to evaluate the quality level of videos transmitted via DSRC and VLC in a platoon-based driving scenario. The simulation results show the benefits of VLC in delivering videos with Quality of Experience (QoE) 30% better compared to DSRC, in scenarios with a different number of hops between the source and destination, as well as videos with different characteristics.
关键词： VANET,Vehicular Visible Light Communication,Platoon,Quality of Experience
更新于2025-09-23 15:22:29
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Indoor Localization Using K-Pairwise Light Emitting Diode Image-Sensor-Based Visible Light Positioning
摘要： A great deal of research has been devoted to studying indoor localization schemes for the development of location-based services. This study investigated an indoor localization system, including subsystems of non-line-of-sight (NLOS) image-sensor-based visible light communications (IS-VLC) and the proposed ??-pairwise light emitting diode (LED) image-sensor-based visible light positioning (IS-VLP), in a unified lighting environment. A smartphone received multiple LED identifiers through the designed NLOS IS-VLC and successfully performed the proposed ??-pairwise LED IS-VLP with ?? = 3 to achieve localization, with maximum localization errors of 2.92 cm and 3.54 cm being obtained for ceiling heights of 100 cm and 150 cm, respectively.
关键词： visible light communications (VLC),Image-sensor-based visible light positioning (VLP),light emitting diode (LED)
更新于2025-09-23 15:21:21