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Investigate quality factor of single tuned passive filter to reduce harmonic of LED lamp
摘要： The use of LED energy-saving lamps is proliferating in the world and ranging from homes, offices to government buildings. The main reason for this is because LED lights have relatively small electrical power consumption. Behind the advantage of saving energy, it turns out that LED lights have a high level of harmonic. Passive filter is recommended to eliminate harmonic. The Quality factor (Q) of a filter will determine its performance. If the Q value is significant, the value of R will be smaller, and the quality of the filter will also be getting better because the energy used by the filter is lowering. It indicates that the heat losses of the filter are small. This work has tested four single tuned passive filter designs on X brand LED lamps with nominal power values of 3W, 4W, and 7W. The inductor values (L) tested were 65mH, 78mH, 91mH, and 115mH, respectively. The test results show that the total harmonic distortion (THD) of voltage on the X brand LED lights does not exceed the IEEE 519-2014 standard limit which is a maximum of 5%, because the highest harmonic voltage is 2.7%. While the highest total harmonic distortion (THD) of current in the LED lamps tested was 154%. The results of installing the first filter (L = 65mH) can reduce THD current up to 90.91%, the second filter (L = 78mH) reduces THD current up to 89.81%, the third filter (L = 91mH) reduces THD current up to 89.57%, while the fourth filter (L = 115mH) reduces THD current up to 86.86%.
关键词： quality factor,LED lamp,total harmonic distortion,passive filter,harmonic
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Distortion Analysis of Interferometric Signal with Auxiliary Emission Modulation in Semiconductor Laser
摘要： The results of analysis of distortion of interferometric signal of a semiconductor laser with the current modulation are presented. The mathematical model of the interferometric signal was refined based on experimental data. Measurements were performed for harmonic and triangular auxiliary modulation, and the effect of laser thermal stabilization on the modulation of the interferometric signal was studied.
关键词： phase modulation,external cavity laser,thermal stabilization,distributed feedback laser,distortion of interferometric signal
更新于2025-09-16 10:30:52
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[IEEE 2019 8th International Conference on Systems and Control (ICSC) - Marrakesh, Morocco (2019.10.23-2019.10.25)] 2019 8th International Conference on Systems and Control (ICSC) - Performance Evaluation of Neural Network Controlled Grid-Connected Photovoltaic System for Power Quality Enhancement
摘要： This paper studies a neural network (NN) control for three-phase grid-connected Photovoltaic (PV) system. This study aims to improve the performances of the system, ensure a high quality of the Total Harmonic Distorsion and extract the maximum power while ensuring unity power factor. A neural network controller is used instead of the two PI regulation loop for grid currents. The Levenberg Marquardt (LM) algorithm is used to train the NN controller and the validation and training data of the utilized neural controller are obtained by simulation of the entire system with the PI controllers calculated for variation of solar irradiance. The simulation study shows that the neural controller indicates significantly more enhanced performance than that of the PI controller, including faster response times, lower overshoot and Total Harmonic Distortion (THD).
关键词： Neural Network Control,Levenberg Marquardt Algorithm,Photovoltaic System,Total Harmonic Distortion,Power Quality
更新于2025-09-16 10:30:52
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A PM <sub/>1</sub> , PM <sub/>2.5</sub> , and PM <sub/>10</sub> Airborne Particle Detector With Laser Illumination Stabilized by Optical Feedback
摘要： The paper proposes a novel approach for direction estimation of a moving pedestrian as perceived in a 2-D coordinate of field camera. The proposed direction estimation method is intended for pedestrian monitoring in traffic control systems. Apart from traffic control, direction of motion estimation is also very important in accident avoidance system for smart cars, assisted living systems, in occlusion prediction for seamless tracking in visual surveillance, and so on. The proposed video-based direction estimation method exploits the notion of perspective distortion as perceived in monocular vision of 2-D camera co-ordinate. The temporal pattern of change in dimension of pedestrian in a frame sequence is unique for each direction; hence, the dimensional change-based feature is used to estimate the direction of motion; eight discrete directions of motion are considered and the hidden Markov model is used for classification. The experiments are conducted over CASIA Dataset A, CASIA Dataset B, and over a self-acquired dataset: NITR Conscious Walk Dataset. The balanced accuracy of direction estimation for these experiments yields satisfactory results with accuracy indices as 94.58%, 90.87%, and 95.83%, respectively. The experiment also justifies with suitable test conditions about the characteristic features, such as robustness toward improper segmentation, partial occlusion, and changing orientation of head or body during walk of a pedestrian. The proposed method can be used as a standalone system or can be integrated with existing frame-based direction estimation methods for implementing a pedestrian monitoring system.
关键词： Visual surveillance,hidden Markov model,occlusion handling,perspective distortion,pedestrian direction estimation
更新于2025-09-16 10:30:52
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Harmonics assessment and mitigation in a photovoltaic integrated network
摘要： This paper presents a comprehensive review of harmonics dominance in PV integrated network. The findings of the review conducted for different scenarios are further supported by the results of an experimental case study exploring the dominance of harmonics in a real time PV integrated microgridunder varying solar irradiance condition. It is concluded that the level of Total Harmonic Distortions (THD) in the power system network varies in different scenarios. Some of the important scenarios are: (i) percentage of PV penetration in distribution network with respect to the types of connected load, (ii) location of PV integration, (iii) effect of harmonic resonance in power network, and (iv) varying power output of PV inverters with varying solar irradiance. A harmonic management system is finally proposed to limit the excessive harmonics in the network under different network conditions. The proposed harmonic management can be used to maintain the THD level within the standard limit and ensures the quality of energy supply to the communities.
关键词： Solar irradiance,Harmonic resonance,Photovoltaic (PV),Total harmonic distortion (THD),Microgrid (MG)
更新于2025-09-16 10:30:52
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[IEEE 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Manama, Bahrain (2019.4.15-2019.4.17)] 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Harmonic analysis of high penetration level of Photovoltaic generation in distribution network and solution studies
摘要： The high penetration level of Photovoltaic (PV) generation in distribution network reduces carbon emissions but also becomes problematic in terms of network management. Harmonic distortion is the main factor studied in this paper and a typical three-bus distribution network is built in MATLAB/Simulink to understand the harmonics problem. Results show that current harmonics are more vulnerable to fluctuate compared to voltage harmonics. Based on existing harmonic standards, total demand distortion of current (TDDi) is evaluated to estimate maximum PV penetration level at Point of Common Coupling (PCC), and the maximum acceptable TDDi at each bus differs according to specific loading and short-circuit levels. Meanwhile, total harmonic distortion of current (THDi) at inverter outputs represents inverter performance. Instead of assessing at standard test conditions (STC), the impact of irradiance variations is studied. Low irradiance results in an increased THDi of the inverter whilst doesn’t explicitly affect TDDi at PCC. A simple and low-cost solution is proposed to dynamically vary the settings of inverter’s filter elements against irradiance, and harmonic distortion at low irradiance of the inverter is successfully mitigated.
关键词： power system,total demand distortion,total harmonic distortion,irradiance,PV penetration level
更新于2025-09-12 10:27:22
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Two-Dimensional Fluorine Distribution in a Heavily Distorted Perovskite Nickel Oxyfluoride Revealed by First-Principles Calculation
摘要： Most perovskite oxyfluorides synthesized to date have cubic structures, wherein fluorine atoms tend to reside at every oxygen site randomly. In this theoretical study, we show a two-dimensional fluorine arrangement in a perovskite nickel oxyfluoride (NdNiO2F) with a large orthorhombic distortion. The site selectivity in the perovskite lattice is due to the orthorhombicity, which stabilizes the two-dimensional cis configurations with shorter Ni?O and longer Ni?F bonds to minimize the electrostatic energy. The electronic structure of NdNiO2F is characterized by its large octahedral rotation and the higher electronegativity of fluorine than oxygen. We also observed how the anion arrangement was affected by the biaxial strain by modeling epitaxial strained thin film on substrate and found that the 2D cis structure remains the most stable. However, the orientation of the two-dimensional structure containing F depends on the magnitude of the biaxial strain. Our findings suggest that fluorine doping in orthorhombic perovskite oxides effectively yields oxyfluorides with anisotropic anion ordering.
关键词： electronic structure,orthorhombic distortion,perovskite oxyfluorides,two-dimensional fluorine arrangement,biaxial strain
更新于2025-09-12 10:27:22
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Analysis of distortion during laser metal deposition of large parts
摘要： Laser Metal Deposition (LMD) of large parts is very challenging technology for aerospace industry. Due to high productivity of several kilograms per hour and nearly unlimited part size, this technology becomes competitive to traditional production technologies of casting, welding and rolling. One of the main problem of large parts manufacturing is the high distortion. Estimation of residual stresses and distortion is necessary to obtain required dimensional accuracy and prevent fracture of additively manufactured parts. Effects of layer-by-layer evolution of stresses and strains was studied by finite-element simulation. It was shown that distortion of axially symmetrical parts can be successfully predicted by the developed simulation procedure. It was established that the effect of increasing cylinder radius is to increase residual radial displacement and curvature of the sidewall. The highest tension hoop and axial stress amounted to 1.15-1.2 times of yield stress near the substrate. If deposited material have a weak ductility (e.g. titanium alloys) there is a high probability that the fracture could occurs in the sidewall near the substrate. Several experimental trials was carried out for validation of accuracy of developed simulation procedure. Shape of build parts was analysed by 3D laser scanner.
关键词： residual stress,laser metal deposition,distortion,finite element method.
更新于2025-09-12 10:27:22
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Investigation of LED Non-linearity on DCO-OFDM and ACO-OFDM in VLC Systems using Multichip RGB LEDs for Indoor Applications
摘要： The impact of the LED non-linearity on the Intensity Modulation Direct Detection (IM-DD) in the VLC using OFDM for white light generated using RGB LEDs for indoor applications is analyzed. This work extends the orders of harmonics for analysis and investigates the impact of this non-linearity issue on OFDM techniques. The wavelengths (Red, Green and Blue) are individually set at the LED and their induced photocurrent in a Si PD is calculated. The result shows that the wavelength corresponding to the 625nm induces 5dB and 3dB more power than 528nm and 458nm respectively. We choose 625nm as the OFDM signal carrier for transmission keeping the other two un-modulated. We compare the effects of the non-linearity of the LED on the two OFDM techniques- Asymmetrical clipped optical (ACO) and Direct current biased optical (DCO). Our simulation results show that the power of the 2nd and 3rd order intermodulation components for ACO-OFDM is 3dB lesser than DCO-OFDM. The required SNR for ACO-OFDM is found to be 3dB lesser as compared to DCO-OFDM. The clipping effect of the LED remains unchanged irrespective of the OFDM variation applied.
关键词： Visible Light Communication,White Light,ACO-OFDM,LED,DCO-OFDM,Non-Linear Distortion
更新于2025-09-12 10:27:22
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Finite element prediction and validation of residual stress profiles in 316L samples manufactured by laser powder bed fusion
摘要： Laser powder bed fusion (LPBF) processes continue to grow in popularity and much progress has been made in recent years. However, due to the extreme thermal gradients present, significant residual stresses are inevitable and can be detrimental during component service. Critical to mitigating these stresses effectively is the ability to model the thermo-mechanical process accurately and efficiently. A simplified FE modelling methodology has been developed and applied to a cylindrical component built in both the horizontal and vertical orientations. The resulting distortion of the parts following a slitting process was compared with those predicted by the model and good agreement to within 5% was found. The final stress fields in the components were predicted by the model and then examined to assess the principal stresses driving the distortion and the causes of difference in results between the two build orientations.
关键词： LPBF,residual stress,finite element modelling,Laser powder bed fusion,distortion
更新于2025-09-12 10:27:22