- 标题
- 摘要
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- 实验方案
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Correcting geometric distortions in stereoscopic 3D imaging
摘要： Motion in a distorted virtual 3D space may cause visually induced motion sickness. Geometric distortions in stereoscopic 3D can result from mismatches among image capture, display, and viewing parameters. Three pairs of potential mismatches are considered, including 1) camera separation vs. eye separation, 2) camera field of view (FOV) vs. screen FOV, and 3) camera convergence distance (i.e., distance from the cameras to the point where the convergence axes intersect) vs. screen distance from the observer. The effect of the viewer’s head positions (i.e., head lateral offset from the screen center) is also considered. The geometric model is expressed as a function of camera convergence distance, the ratios of the three parameter-pairs, and the offset of the head position. We analyze the impacts of these five variables separately and their interactions on geometric distortions. This model facilitates insights into the various distortions and leads to methods whereby the user can minimize geometric distortions caused by some parameter-pair mismatches through adjusting of other parameter pairs. For example, in postproduction, viewers can correct for a mismatch between camera separation and eye separation by adjusting their distance from the real screen and changing the effective camera convergence distance.
关键词： display parameters,stereoscopic 3D,viewing parameters,geometric distortions,distortion correction,motion sickness,camera parameters
更新于2025-09-23 15:22:29
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Ferroelectric Origin and Distortion Modes in Doped BiFeO <sub>3</sub> by Crystallography Approach
摘要： There are conflicts about the ferroelectric origin and the relationship of two distortion modes, namely, the ferroelectric (FE) mode and antiferrodistortive (AFD) mode. Here the two distortion modes and enhanced ferroelectric properties (Pr=89.5 μC cm-2) are observed in BiFeO3 thin films doped with small radius Mg2+ (A-site) deposited on (111) Pt/Ti/SiO2/Si substrates by a sol-gel method, the relationship of the two distortion modes turns from cooperative to competitive as the FE mode strengthens. A new explanation of ferroelectric origin and distortion modes in doped BiFeO3 by the Defect Dipoles Driven Distortions Theory (abbreviate DDD) from crystallography is reported. Meanwhile, the crystal structure regulation mechanism of doped BiFeO3 thin films with substantially enhanced ferroelectric properties is also put forward. The distances of the positive and negative charge center in [FeO6] octahedrons evidently increase by Mg2+ doping compared with that in the Bi0.9Sm0.1Fe0.95Mn0.05O3 (BSFMO). The change of distances is contributed to the law of the atomic migration from the move of oxygen vacancies and the attraction of defect dipoles. A positive effect on ferroelectric properties of the appropriate increase in oxygen vacancies is explored, which is explained by "the probability of possible position that oxygen vacancies occurred" and "the relationship between the leakage current and the overlapping oxygen positions". The potential structure and more suitable doping ions are successfully predicted by the crystal structure regulation mechanism. In addition, it brings a new direction for the search of other structure regulation ions so as to realize the perfect ferroelectric properties for practical application, which will become an important beginning of ferroelectric materials design.
关键词： ferroelectric properties,structural distortions,crystallography,ferroelectric origin,defect dipoles
更新于2025-09-23 15:22:29
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Addressing Safety Issues in Development of Quantum Dot Incorporated EVA Lamination of Photovoltaic Devices
摘要： Most publicly available image quality databases have been created under highly controlled conditions by introducing graded simulated distortions onto high-quality photographs. However, images captured using typical real-world mobile camera devices are usually afflicted by complex mixtures of multiple distortions, which are not necessarily well-modeled by the synthetic distortions found in existing databases. The originators of existing legacy databases usually conducted human psychometric studies to obtain statistically meaningful sets of human opinion scores on images in a stringently controlled visual environment, resulting in small data collections relative to other kinds of image analysis databases. Toward overcoming these limitations, we designed and created a new database that we call the LIVE In the Wild Image Quality Challenge Database, which contains widely diverse authentic image distortions on a large number of images captured using a representative variety of modern mobile devices. We also designed and implemented a new online crowdsourcing system, which we have used to conduct a very large-scale, multi-month image quality assessment (IQA) subjective study. Our database consists of over 350,000 opinion scores on 1162 images evaluated by over 8100 unique human observers. Despite the lack of control over the experimental environments of the numerous study participants, we demonstrate excellent internal consistency of the subjective data set. We also evaluate several top-performing blind IQA algorithms on it and present insights on how the mixtures of distortions challenge both end users as well as automatic perceptual quality prediction models. The new database is available for public use at http://live.ece.utexas.edu/research/ChallengeDB/index.html.
关键词： crowdsourcing,subjective image quality assessment,authentic distortions,Perceptual image quality
更新于2025-09-23 15:19:57
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Fibrous Al-Doped ZnO Thin Film Ultraviolet Photodetectors with Improved Responsivity and Speed
摘要： Most publicly available image quality databases have been created under highly controlled conditions by introducing graded simulated distortions onto high-quality photographs. However, images captured using typical real-world mobile camera devices are usually afflicted by complex mixtures of multiple distortions, which are not necessarily well-modeled by the synthetic distortions found in existing databases. The originators of existing legacy databases usually conducted human psychometric studies to obtain statistically meaningful sets of human opinion scores on images in a stringently controlled visual environment, resulting in small data collections relative to other kinds of image analysis databases. Toward overcoming these limitations, we designed and created a new database that we call the LIVE In the Wild Image Quality Challenge Database, which contains widely diverse authentic image distortions on a large number of images captured using a representative variety of modern mobile devices. We also designed and implemented a new online crowdsourcing system, which we have used to conduct a very large-scale, multi-month image quality assessment (IQA) subjective study. Our database consists of over 350 000 opinion scores on 1162 images evaluated by over 8100 unique human observers. Despite the lack of control over the experimental environments of the numerous study participants, we demonstrate excellent internal consistency of the subjective data set. We also evaluate several top-performing blind IQA algorithms on it and present insights on how the mixtures of distortions challenge both end users as well as automatic perceptual quality prediction models. The new database is available for public use at http://live.ece.utexas.edu/research/ChallengeDB/index.html.
关键词： crowdsourcing,subjective image quality assessment,authentic distortions,Perceptual image quality
更新于2025-09-23 15:19:57
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Improved Coyote Optimization Algorithm for Optimally Installing Solar Photovoltaic Distribution Generation Units in Radial Distribution Power Systems
摘要： This paper proposes an improved coyote optimization algorithm (ICOA) for optimizing the location and sizing of solar photovoltaic distribution generation units (PVDGUs) in radial distribution systems. In the considered problem, four single objectives consisting of total power losses, capacity of all PVDGUs, voltage profile index, and harmonic distortions are minimized independently while satisfying branch current limits, voltage limits, and harmonic distortion limits exactly and simultaneously. The performance of the proposed ICOA method has been improved significantly since two improvements were carried out on the two new solution generations of the conventional coyote optimization algorithm (COA). By finding four single objectives from two IEEE distribution power systems with 33 buses and 69 buses, the impact of each proposed improvement and two proposed improvements on the real performance of ICOA has been investigated. ICOA was superior to COA in terms of capability of finding higher quality solutions, more stable search ability, and faster convergence speed. Furthermore, we have also applied five other metaheuristic algorithms consisting of biogeography-based optimization (BBO), genetic algorithm (GA), particle swarm optimization algorithm (PSO), sunflower optimization (SFO), and salp swarm algorithm (SSA) for dealing with the same problem and evaluating further performance of ICOA. The result comparisons have also indicated the outstanding performance of ICOA because it could find much better results than these methods, especially SFO, SSA, and GA. Consequently, the proposed ICOA is a very effective method for finding the optimal location and capacity of PVDGUs in radial distribution power systems.
关键词： voltage profile,harmonic distortions,power losses,coyote optimization algorithm,solar photovoltaic distribution generation units,radial distribution systems
更新于2025-09-23 15:19:57
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Efficient hot-band pumped Nd:YLF laser
摘要： Most publicly available image quality databases have been created under highly controlled conditions by introducing graded simulated distortions onto high-quality photographs. However, images captured using typical real-world mobile camera devices are usually afflicted by complex mixtures of multiple distortions, which are not necessarily well-modeled by the synthetic distortions found in existing databases. The originators of existing legacy databases usually conducted human psychometric studies to obtain statistically meaningful sets of human opinion scores on images in a stringently controlled visual environment, resulting in small data collections relative to other kinds of image analysis databases. Toward overcoming these limitations, we designed and created a new database that we call the LIVE In the Wild Image Quality Challenge Database, which contains widely diverse authentic image distortions on a large number of images captured using a representative variety of modern mobile devices. We also designed and implemented a new online crowdsourcing system, which we have used to conduct a very large-scale, multi-month image quality assessment (IQA) subjective study. Our database consists of over 350 000 opinion scores on 1162 images evaluated by over 8100 unique human observers. Despite the lack of control over the experimental environments of the numerous study participants, we demonstrate excellent internal consistency of the subjective data set. We also evaluate several top-performing blind IQA algorithms on it and present insights on how the mixtures of distortions challenge both end users as well as automatic perceptual quality prediction models. The new database is available for public use at http://live.ece.utexas.edu/research/ChallengeDB/index.html.
关键词： crowdsourcing,subjective image quality assessment,authentic distortions,Perceptual image quality
更新于2025-09-19 17:13:59
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[Laser Institute of America ICALEO? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22–26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Adaptive optics for intra-volume engraving of glass with ultra-short laser pulses
摘要： Within the frame of high precision ultrafast laser processing of transparent materials, we report here on the use of adaptive optics as a tool for intra-volume laser engraving of glass. With the active monitoring of the laser beam wavefront, the repartition of the above-threshold energy in the focal volume is actively detected. Therefore, the elongation of the laser-induced modification due to longitudinal spherical aberration can be minimized or emphasized on demand. Indeed, the industrial adaptive optics set up, made of a wavefront sensor and a deformable mirror, permits the management of each wavefront aberration as RMS values of chosen Zernike polynomials coefficients. This technique allows the control of the processing of transparent dielectrics, whatever the index of refraction and the depth are. This study addresses the precise correlation between wavefront distortions and intra-volume modifications in borosilicate glass obtained with a 300 fs Yb-doped fiber laser running at 1030 nm. The effects of the 3rd and 5th orders of longitudinal spherical aberrations on the laser-induced marking of the bulk are investigated with the purpose of precisely controlling the length of the interaction volume in the illuminated dielectric material. We show here a minimization of the total length of the marking by 65% at 600 μm in depth, from the natural wavefront to the optimized one, close to the diffraction limit.
关键词： wavefront distortions,ultra-short laser pulses,intra-volume engraving,adaptive optics,glass,longitudinal spherical aberrations
更新于2025-09-16 10:30:52
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Coupled structural distortions, domains, and control of phase competition in polar
摘要： Materials with coupled or competing order parameters display highly tunable ground states, where subtle perturbations reveal distinct electronic and magnetic phases. These states generally are underpinned by complex crystal structures, but the role of structural complexity in these phases often is unclear. We use group-theoretic methods and first-principles calculations to analyze a set of coupled structural distortions that underlie the polar charge and orbitally ordered antiferromagnetic ground state of A-site ordered SmBaMn2O6. We show that these distortions play a key role in establishing the ground state and stabilizing a network of domain wall vortices. Furthermore, we show that the crystal structure provides a knob to control competing electronic and magnetic phases at structural domain walls and in epitaxially strained thin films. These results provide new understanding of the complex physics realized across multiple length scales in SmBaMn2O6 and demonstrate a framework for systematic exploration of correlated and structurally complex materials.
关键词： phase competition,first-principles calculations,domains,coupled structural distortions,group-theoretic methods,polar SmBaMn2O6
更新于2025-09-16 10:30:52
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Effect of Process Parameters on Residual Stresses, Distortions, and Porosity in Selective Laser Melting of Maraging Steel 300
摘要： Selective laser melting (SLM) is one of the most well-known additive manufacturing methods available for the fabrication of functional parts from metal powders. Although SLM is now an established metal additive manufacturing technique, its widespread application in industry is still hindered by inherent phenomena, one of which is high residual stresses. Some of the e?ects of residual stresses–such as warping and thermal stress-related cracking–cannot be corrected by post processing. Therefore, establishing input process parameter combinations that result in the least residual stress magnitudes and related distortions and/or cracking is critical. This paper presents the in?uence of laser power, scanning speed, and layer thickness on residual stresses, distortions and achievable density for maraging steel 300 steel parts in order to establish the most optimum input parameter combinations. An analysis of the interdependence between process outcomes shows that high residual stress magnitudes lead to high dimensional distortions in the ?nished parts, whilst porous parts su?er relatively lower residual stresses and associated distortions.
关键词： selective laser melting,distortions,porosity,residual stresses
更新于2025-09-16 10:30:52
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Distortion minimization of laser beam welded components by the use of finite element simulation and Artificial Intelligence
摘要： Welded components often require costly efforts to compensate for the thermally induced distortions. This is usually done by applying a specific pre-deformation or by reworking, for example by thermal straightening. These approaches are not practicable for joining complex structures. Therefore, a method that is capable of minimizing the distortions of a complex frame structure with multiple welds is presented. A meta-model by means of an Artificial Neural Network is used to predict the local distortions depending on the welding parameters within sub-areas. A genetic algorithm is utilized to efficiently find suitable welding parameters for the global structure. It could be shown that by applying the method, distortion minimized parameters from more than one billion potential parameter combinations are identified both efficiently and reliably.
关键词： Component distortions,Artificial Intelligence,Metamodeling,Genetic algorithms,FEM simulation,Artificial Neural Networks,Laser beam welding
更新于2025-09-12 10:27:22