- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Interaction between Bi Dopants and Intrinsic Defects in LiNbO <sub/>3</sub> from Local and Hybrid Density Functional Theory Calculations
摘要： The interactions between Bi dopants including Bi-substituting Li (BiLi) and Bi-substituting Nb (BiNb) and the intrinsic antisite defects (NbLi) and Li vacancies (VLi) in LiNbO3 are investigated using local and hybrid density functional theories. Three charge-compensated defect clusters, BiLi4+ + NbLi4+ + 8VLi-, BiLi4+ + 4VLi-, and BiLi0 + 4VLi- + BiNb4+, are modeled in this work to investigate the effects of the Bi concentration. The most stable cluster configurations, the Bi-doping stability in the clusters, and the electronic state interaction between Bi and intrinsic defects have been studied in detail. It is found that BiLi4+ has a stronger electron-capturing ability than NbLi4+ in Bi-doped congruent LiNbO3. The BiLi-doping-induced local lattice distortion and the electron-trapping behavior remain unchanged with increasing Bi-doping concentration. However, the position of the Bi defect states in the band gap is found to be shifted in congruent LiNbO3. This is mainly attributed to the large lattice relaxation induced by the large number of Li vacancies instead of the ionic level redistribution caused by the direct interaction between Bi and intrinsic defects.
关键词： LiNbO3,Bi dopants,lattice distortion,defect clusters,intrinsic defects,density functional theory,electron trapping
更新于2025-09-19 17:15:36
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Nonlinearity mitigation in multi-IFoF-based mobile fronthaul transmission using spectral power shaping
摘要： We propose a spectral power shaping technique for use in intermediate frequency (IF) over fiber systems. The technique redistributes the power of nonlinear components by adjusting the spectral power of the signal. Experiments performed using 10 km distance transmission system show that the proposed technique effectively controls the power of the nonlinear components in a broadband system. The feasibility of the proposed technique was experimentally verified in terms of the error vector magnitude (EVM) and degree of channel linearity.
关键词： IFoF system,Intermodulation distortion,Nonlinearity mitigation,Spectral power shaping
更新于2025-09-19 17:15:36
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Wavelength-stable 1.1 kW diode laser array cooled by liquid metal
摘要： While rate–distortion optimized quantization (RDOQ) technique provides nontrivial coding gain in High Efficiency Video Coding (HEVC), it also involves considerable computations, whereby the complexity of quantization is significantly increased. In this paper, two schemes (the RDOQ bypass decision and the simplified level adjustment) are investigated to reduce the complexity of the quantization process in HEVC with RDOQ. The RDOQ bypass decision method initially selects the transform blocks for which the RDOQ is expected to give less/or no coding gain and enables the conventional uniform scalar quantization to be applied to these transform blocks instead of the RDOQ. The simplified level adjustment method only estimates the difference in rate–distortion costs among the candidate quantization levels to enable the encoder to select an optimal quantization level at a much reduced computational cost. Furthermore, the proposed simplified level adjustment scheme is designed so that it can be implemented in lookup tables. Experimental results show that the proposed fast method achieves 14.3% quantization complexity reduction in all intra main conditions, 15.2% in the random access main condition, and 14.9% in the low delay main condition on average with virtually no coding loss compared with the conventional quantization process with the RDOQ.
关键词： rate–distortion optimized quantization (RDOQ),Fast quantization,High Efficiency Video Coding (HEVC)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Unmanned Systems (ICUS) - Beijing, China (2019.10.17-2019.10.19)] 2019 IEEE International Conference on Unmanned Systems (ICUS) - Observability Enhancement of the Target Tracking Model Based on Infrared Semi-strapdown Seeker
摘要： A large petrochemical company installed nearly 50 000 hp of electrical submersible pumps (ESPs) at an existing midwest U.S. oil ?eld. Being equipped with adjustable-speed drives (ASDs), these ESPs introduced high levels of current harmonic dis-tortion, which resulted in 14%–19% voltage harmonic distortion at the electrical utility supply. Initially, the utility noticed the low power factor (PF) and had the oil company pay for the installation of power factor correction (PFC) capacitors on their medium-voltage supply. Once installed, the utility began to have problems with these capacitors and continued to receive complaints from other customers adjacent to the oil ?eld; thus, they enforced har-monic limits, as de?ned by IEEE Std 519, at all points of common coupling. Measurements were made with a harmonic analyzer at several locations throughout the electrical system to quantify harmonics and determine the effect the ESPs were having on the utility distribution system. Computer simulations were performed to analyze different methods of harmonic mitigation. Ultimately, passive harmonic ?lters were installed on all ESPs in phases. In addition, the PFC capacitors were permanently disconnected after determining that a power system resonance condition existed. Once all phases of the project were complete, the voltage distortion level decreased to below 5%, and PF improved to near unity without the PFC capacitors. This paper will describe the effect of harmonics on the electrical distribution system caused by ASDs, practical solutions to excessive voltage harmonic distortion, reso-nance issues with PFC capacitors, and the challenges associated with different methods of harmonic mitigation.
关键词： resonance,Adjustable-speed drives (ASDs),electrical submersible pumps (ESPs),harmonic quantities,harmonics,capacitors,harmonic ?lters,harmonic mitigation,power factor correction (PFC),harmonic distortion
更新于2025-09-19 17:13:59
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L vs. LCL Filter for Photovoltaic Grid-Connected Inverter: A Reliability Study
摘要： The increasing use of photovoltaic systems entails the use of new technologies to improve the efficiency and power quality of the grid. System performance is constantly increasing, but its reliability decreases due to factors such as the uncontrolled operation, the quality of the design and quantity of components, and the use of nonlinear loads that may lead to distortion in the signal, which directly affects the life of the system globally. This article presents an analysis of the reliability of a single-phase full-bridge inverter for active power injection into the grid, which considers the inverter stage with its coupling stage. A comparison between an L filter and an LCL filter, which comprise the coupling stage, is made. Reliability prediction is based on metrics, failure rate, mean time between failures, and total harmonic distortion. The analysis and numerical simulation are performed. Finally, filter considerations are suggested to extend the reliability of the inverter in a photovoltaic system.
关键词： photovoltaic systems,LCL filter,L filter,reliability,total harmonic distortion
更新于2025-09-19 17:13:59
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Steady-state equivalent circuit of LED bulbs accounting for the current harmonics
摘要： Nowadays, the light-emitting diode (LED) bulb is one of the preferred choice in lighting system design. Electrical models of the LED lamps have to consider their nonlinear behavior involving current distortion on the mains. With this purpose, an equivalent electrical circuit emulating the current drawn by a LED Bulbs is carried out. In this work, different lamps have been tested under variable supply voltage. The comparison between the simulations performed by means of PSpice and the experimental measurements has highlighted that linear interpolation for the amplitude of each harmonic current, as function of the voltage on the main, provides a good estimation of the total current waveform.
关键词： LED Bulbs,power conversion,LED lamps,Current harmonics,equivalent circuits,lighting,total harmonic distortion,power quality
更新于2025-09-19 17:13:59
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Local deformation and macro distortion of TC4 titanium alloy during laser shock processing
摘要： Experimental investigation has been carried out to understand the local deformation, macro distortion, and residual stress distribution of TC4 titanium alloy thin plate with different thickness during laser peening processing. The results show that the geometry distortions generate different profile directions depending on the laser shock processing condition. The deformation coefficient λ based on laser power density and sheet thickness is used to predict the macro deformation mode. When λ < 0.212, no macro distortion is produced; when 0.212 < λ < 0.58, volume is transferred along the top surface, the geometric distortion direction is away the laser beam, compressive residual stress is induced on the surface, and convex deformation is produced; when 0.65 < λ, volume is transferred along the bottom surface, the macro distortion direction is toward the laser beam, tensile residual stress is induced on the surface, and concave deformation is produced; the threshold of concave and convex deformation is about 0.62. The deformation coefficient λ and the threshold of concave and convex deformation can be adopted to predict and control the geometry distortion of TC4 titanium alloy thin plate during laser shock processing.
关键词： Thin plate,Residual stress,Geometry distortion,Laser shock peening
更新于2025-09-19 17:13:59
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29.4: A laser current control algorithm to avoid color distortion in laser projection displays
摘要： Laser display technology has gradually become an important solution for large screen display. As a mature lighting technology in recent decades, phosphor has been widely used in the field of lighting and display. As a solid-state light source, it has the advantages of low power consumption, environmental protection, rich color and dynamic modulation. The luminescent efficiency of phosphors varies with temperature, which results in the non-linearity of phosphor emission when the light source is dynamically modulated and the color temperature drift of the display image. In this paper, a control model of color temperature of laser TV display changing with laser current and temperature is established. The color temperature of laser TV is corrected by using current compensation control algorithm. The problem of color temperature drift caused by the change of phosphor conversion efficiency with temperature is solved. The color temperature deviation is 1118 K in the brightness range of the light source before compensation. By compensating and controlling the laser current, the ratio of blue light and phosphor is constant when the brightness changes, thus ensuring the color temperature constant when the brightness of the laser light source changes. The color temperature deviation is 50K in the brightness range. By analyzing the different brightness of the display image, the stability of the color temperature is improved.
关键词： laser phosphor,dynamic compensation,color distortion
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW) - London, United Kingdom (2019.6.18-2019.6.21)] 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW) - A Phase-controlled Stacked-transmitter Wireless Power Transfer System for Magnetic Field Beamforming
摘要： While rate–distortion optimized quantization (RDOQ) technique provides nontrivial coding gain in High Efficiency Video Coding (HEVC), it also involves considerable computations, whereby the complexity of quantization is significantly increased. In this paper, two schemes (the RDOQ bypass decision and the simplified level adjustment) are investigated to reduce the complexity of the quantization process in HEVC with RDOQ. The RDOQ bypass decision method initially selects the transform blocks for which the RDOQ is expected to give less/or no coding gain and enables the conventional uniform scalar quantization to be applied to these transform blocks instead of the RDOQ. The simplified level adjustment method only estimates the difference in rate–distortion costs among the candidate quantization levels to enable the encoder to select an optimal quantization level at a much reduced computational cost. Furthermore, the proposed simplified level adjustment scheme is designed so that it can be implemented in lookup tables. Experimental results show that the proposed fast method achieves 14.3% quantization complexity reduction in all intra main conditions, 15.2% in the random access main condition, and 14.9% in the low delay main condition on average with virtually no coding loss compared with the conventional quantization process with the RDOQ.
关键词： High Efficiency Video Coding (HEVC),Fast quantization,rate–distortion optimized quantization (RDOQ)
更新于2025-09-19 17:13:59
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Design and performance analysis of improved Adaline technique for synchronization and load compensation of grida??tied photovoltaic system
摘要： The paper discusses the design, modeling, simulation, and implementation of improved Adaline technique, which has been used for grid synchronization as well as extended further for load compensation. A simple but effective method is proposed to improve the performance of the conventional Adaline technique. The conventional Adaline controller uses a fixed learning rate while the proposed Adaline is developed using variable learning, which improves both the steady-state and dynamic response. Simulation and experimental results have been demonstrated, which confirm the feasibility of the proposed approach. Suitable performance comparisons highlight the effectiveness of the proposed approach.
关键词： power quality,ANN,phase-locked loops,synchronization,harmonic distortion
更新于2025-09-19 17:13:59