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Mansencal, Thomas; Mauderer, Michael; Parsons, Michael; Shaw, Nick; Wheatley, Kevin; Cooper, Sean P.; Vandenberg, Jean D.; Canavan, Luke; Crowson, Katherine; Lev, Ofek; Leinweber, Katrin; Sharma, Shriramana; Sobotka, Troy James; Moritz, Dominik; Pppp, Matt; Rane, Chinmay; Eswaramoorthy, Pavithra; Mertic, John; Pearlstine, Ben; Leonhardt, Manuel; Niemitalo, Olli; Szymański, Marek; Schambach, Maximilian; Huang, Sianyi; Wei, Mike; Joywardhan, Nishant; Wagih, Omar; Redman, Paweł; Goldstone, Joseph; Hill, Stephen

doi:10.5281/zenodo.3757045

Cited by 4 publications

(4 citation statements)

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“…This equation is the current standard measure for small to medium color differences and is therefore well suited to measure small errors in LAT values with respect to the viridis colormap. For our application, we use the default recommended hyperparameters [ 49 ].…”

Section: Methodsmentioning

confidence: 99%

Manifold Approximating Graph Interpolation of Cardiac Local Activation Time

Hellar

Cosentino²,

John³

et al. 2022

IEEE Trans. Biomed. Eng.

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Local activation time (LAT) mapping of cardiac chambers is vital for targeted treatment of cardiac arrhythmias in catheter ablation procedures. Current methods require too many LAT observations for an accurate interpolation of the necessarily sparse LAT signal extracted from intracardiac electrograms (EGMs). Additionally, conventional performance metrics for LAT interpolation algorithms do not accurately measure the quality of interpolated maps. We propose, first, a novel method for spatial interpolation of the LAT signal which requires relatively few observations; second, a realistic sub-sampling protocol for LAT interpolation testing; and third, a new color-based metric for evaluation of interpolation quality that quantifies perceived differences in LAT maps. Methods: We utilize a graph signal processing framework to reformulate the irregular spatial interpolation problem into a semi-supervised learning problem on the manifold with a closed-form solution. The metric proposed uses a color difference equation and color theory to quantify visual differences in generated LAT maps. Results: We evaluate our approach on a dataset consisting of seven LAT maps from four patients obtained by the CARTO electroanatomic mapping system during premature ventricular complex (PVC) ablation procedures. Random sub-sampling and reinterpolation of the LAT observations show excellent accuracy for relatively few observations, achieving on average 6% lower error than state-of-the-art techniques for only 100 observations. Conclusion: Our study suggests that graph signal processing methods can improve LAT mapping for cardiac ablation procedures. Significance: The proposed method can reduce patient time in surgery by decreasing the number of LAT observations needed for an accurate LAT map.

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Section: Methodsmentioning

confidence: 99%

Manifold Approximating Graph Interpolation of Cardiac Local Activation Time

Hellar

Cosentino²,

John³

et al. 2022

IEEE Trans. Biomed. Eng.

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“…One is a horizontally scanned image, which is the target image i m,n from which the illumination variations are going to be eliminated, and the other is a vertically scanned image whose one column is used as the extra scan e m,n . (Mansencal et al, 2020) from the horizontal scan, the vertical scan, and the results of the Naïve and the proposed methods. The scan times were 1099 s for the horizontal image and 4 s for one of the columns of the vertical image.…”

Section: Quantitative Evaluationmentioning

confidence: 99%

“…Figure 4 depicts the RGB images synthesized by an opensource Python package for colour science(Mansencal et al, 2020) from the horizontal scan, the vertical scan, and the results of the Naïve and the proposed methods. The scan times were 1099 s for the horizontal image and 4 s for one of the columns of the vertical image.…”

mentioning

confidence: 99%

“…Fig.12Captured image and mitigation results from a field experiment in a cathedral. Each hyperspectral image was converted to an RGB image using(Mansencal et al, 2020). a An RGB image photographed by a Ricoh Theta (Ricoh, Inc.), b a horizontal scan, c the result mitigated by the Naïve method, d the result mitigated by the proposed method, and e the difference between the horizontal scan and the mitigated result, which represents the intensity changes in the sunlight during the horizontal scan with respect to those during the single-column scan.…”

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confidence: 99%

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Eliminating Temporal Illumination Variations in Whisk-broom Hyperspectral Imaging

et al. 2022

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We propose a method for eliminating the temporal illumination variations in whisk-broom (point-scan) hyperspectral imaging. Whisk-broom scanning is useful for acquiring a spatial measurement using a pixel-based hyperspectral sensor. However, when it is applied to outdoor cultural heritages, temporal illumination variations become an issue due to the lengthy measurement time. As a result, the incoming illumination spectra vary across the measured image locations because different locations are measured at different times. To overcome this problem, in addition to the standard raster scan, we propose an additional perpendicular scan that traverses the raster scan. We show that this additional scan allows us to infer the illumination variations over the raster scan. Furthermore, the sparse structure in the illumination spectrum is exploited to robustly eliminate these variations. We quantitatively show that a hyperspectral image captured under sunlight is indeed affected by temporal illumination variations, that a Naïve mitigation method suffers from severe artifacts, and that the proposed method can robustly eliminate the illumination variations. Finally, we demonstrate the usefulness of the proposed method by capturing historic stained-glass windows of a French cathedral.

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Ultrathin Solar Cell With Magnesium-Based Optical Switching for Window Applications

Götz‐Köhler

Meddeb

Gehrke

et al. 2021

IEEE J. Photovoltaics

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Photovoltaic windows that can be switched between 4 transparent and energy harvesting mode can be realized by using 5 ultrathin solar absorbers embedded in an optical nanocavity. In the 6 present work, we use a 5 nm thick amorphous germanium absorber 7 integrated in a magnesium-based thin film optical cavity, which 8 switches from an absorptive to a transparent state due to hydrogen 9 absorption. We analyze the influence of the mirror layer thickness 10 on the light absorption, photocurrent generation, and transmission 11 as well as color neutrality of the device. The optical properties are 12 studied by 1-D transfer-matrix method by changing Mg thickness 13 between 0 and 100 nm, then compared to the experimental results of 14 fabricated devices. When the thickness of Mg increases, the switch-15 able average transparency varies between 25% and 0%, while the 16 power conversion efficiency rises up to 2.3%. The applicability of 17 the device is tested by modeling the annual power generation in 18 realistic scenarios. The influence of the cardinal orientation and 19 the seasons on the switchable photovoltaic window implemented in 20 a building facade with the abovementioned parameters is analyzed 21 for different switching scenarios. 22 Index Terms-Magnesium optical switching, smart window, 23 switchable solar cell, ultrathin solar cell. 24 I. INTRODUCTION 25 I N MODERN buildings, huge glass facades often separate the 26 interior from the exterior environment. They are supposed to 27 supply thermal and visual comfort to the inner of the building. 28 To improve this comfort, shading systems have to be imple-29 mented, which provide effective light and heat management 30 [1]-[3]. Dynamic daylight control can be provided by smart 31 windows, which attracted great interest in recent years [4]-[8]. 32 These windows are able to reduce the amount of energy needed 33 for cooling in the building [9]. The emergence of switchable Q1 34 solar cells added a new energy harvesting capability to these 35 smart windows. While still being able to dynamically block 36 sunlight from entering the interior of a building, these smart 37 solar windows generate electricity at the same time. For the 38 realization of a smart photovoltaic window, a technical solution 39 enabling reversible switching from a transparent state to an ab-40 sorbing photovoltaic state is required. Different approaches are 41 523

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Colour 0.3.16

Cited by 4 publications

References 0 publications

Manifold Approximating Graph Interpolation of Cardiac Local Activation Time

Manifold Approximating Graph Interpolation of Cardiac Local Activation Time

Eliminating Temporal Illumination Variations in Whisk-broom Hyperspectral Imaging

Ultrathin Solar Cell With Magnesium-Based Optical Switching for Window Applications

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