LFS-GAN: Lifelong Few-Shot Image Generation

We address a challenging lifelong few-shot image generation task for the first time. In this situation, a generative model learns a sequence of tasks using only a few samples per task. Consequently, the learned model encounters both catastrophic forgetting and overfitting problems at a time. Existing studies on lifelong GANs have proposed modulation-based methods to prevent catastrophic forgetting. However, they require considerable additional parameters and cannot generate high-fidelity and diverse images from limited data. On the other hand, the existing few-shot GANs suffer from severe catastrophic forgetting when learning multiple tasks. To alleviate these issues, we propose a framework called Lifelong Few-Shot GAN (LFS-GAN) that can generate high-quality and diverse images in lifelong few-shot image generation task. Our proposed framework learns each task using an efficient task-specific modulator - Learnable Factorized Tensor (LeFT). LeFT is rank-constrained and has a rich representation ability due to its unique reconstruction technique. Furthermore, we propose a novel mode seeking loss to improve the diversity of our model in low-data circumstances. Extensive experiments demonstrate that the proposed LFS-GAN can generate high-fidelity and diverse images without any forgetting and mode collapse in various domains, achieving state-of-the-art in lifelong few-shot image generation task. Surprisingly, we find that our LFS-GAN even outperforms the existing few-shot GANs in the few-shot image generation task. The code is available at Github.Comment: 20 pages, 19 figures, 14 tables, ICCV 2023 Poste

V shaped Tröger oligothiophenes boost triplet formation by ct mediation and symmetry breaking

A new family of molecules obtained by coupling Tröger's base unit with dicyanovinylene-terminated oligothiophenes of different lengths has been synthesized and characterized by steady-state stationary and transient time-resolved spectroscopies. Quantum chemical calculations allow us to interpret and recognize the properties of the stationary excited states as well as the time-dependent mechanisms of singlet-to-triplet coupling. The presence of the diazocine unit in Tröger's base derivatives is key to efficiently producing singlet-to-triplet intersystem crossing mediated by the role of the nitrogen atoms and of the almost orthogonal disposition of the two thiophene arms. Spin-orbit coupling-mediated interstate intersystem crossing (ISC) is activated by a symmetry-breaking process in the first singlet excited state with partial charge transfer character. This mechanism is a characteristic of these molecular triads since the independent dicyanovinylene-oligothiophene branches do not display appreciable ISC. These results show how Tröger's base coupling of organic chromophores can be used to improve the ISC efficiency and tune their photophysics.Funding for open Access charge: Universidad de Málaga / CBUA. The authors thank the Spanish Ministry of Science and Innovation (projects MICIN/FEDER PID2021-127127NB- I00, PID2019-109555GB-I00, PID2022-136231NB-I00, PID2022-138908NB-C33, and TED2021-129886B−C43), the Junta de Andalucía (PROYEXCEL-0328), and the Eusko Jaurlaritza (project PIBA19-0004)

Радиопоглощающие материалы на основе наполненного полиэтилена

Радиопоглощающие материалы (РПМ) и электромагнитные экраны на их основе являются одним из эффективных средств решения проблем электромагнитной безопасности и электромагнитной совместимости радиоэлектронной техники. Среди многообразия РПМ свою нишу занимают материалы на основе наполненного полиэтилена. Для композитных РПМ на основе полиэтилена, содержащего различные функциональные дисперсные наполнители и армированные электропроводящими тканями, установлены оптимальные значения толщины образцов, степени наполнения, при которых ослабление энергии СВЧ-излучения максимально. Оценены радиофизические параметры полимерных композитных РПМ в диапазоне частот 2,0–27,0 ГГц при нормальном падении на образец электромагнитной волны. С применением растровой электронной микроскопии изучена структура композитных РПМ. По технологическим и технико-экономическим критериям наиболее перспективными средствами радиозащиты являются РПМ на основе функционально наполненных термопластов. РПМ относятся к материалам двойного назначения и могут быть использованы при создании малозаметных объектов, в том числе летательных аппаратов.Radioabsorbing materials and electromagnetic screen based on these materials are one of the effective means of solving electromagnetic safety and electromagnetic compatibility problems of radioelectronic equipment. Among the variety of radioabsorbing materials loaded polyethylene based materials hold their own place. For composite radioabsorbing materials based on polyethylene including various functional dispersed fillers and reinforced with conducting textiles optimum thickness values of the samples are specified and also the levels of filling at which the attenuation of microwave radiation reaches maximum. Radio physical parameters of polymer composite radioabsorbinhg materials in the range of frequencies of 2,0–27,0 GHz at normal incidence of electromagnetic wave on a sample are evaluated. Using raster electronic microscopy the structure of composite radioabsorbing materials have been studied. Evaluated by technological and technical-economic parameters the most promising means of radioprotection are radioabsorbing materials based on functionally loaded thermoplastic materials. Radioabsorbing materials are referred to as double-purpose materials and can be used for making barely visible objects such as flying apparatuses

URIE: Universal Image Enhancement for Visual Recognition in the Wild

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Context-Aware Memory Profiling for Speculative Parallelism

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Spatial and Temporal Variation in PBL Height over the Korean Peninsula in the KMA Operational Regional Model

Spatial and temporal variations in planetary boundary layer height (PBLH) over the Korean Peninsula and its surrounding oceans are investigated using a regional grid model operated at the Korea Meteorological Administration (KMA). Special attention is placed on daily maximum mixing height for evaluation against two radiosonde observation datasets. In order to construct a new high-resolution PBLH database with 3-hour time and 10 km spatial resolution, short-term integrations with the regional model are carried out for a one-year period from June 2010 to May 2011. The resulting dataset is then utilized to explore the seasonal patterns of horizontal PBLH distribution over the peninsula for one year. Frequency distributions as well as monthly and diurnal variations of PBLH at two selected locations are examined. This study reveals specific spatiotemporal structure of boundary layer depth over the Korean Peninsula for the first time at a relatively high-resolution scale. The results are expected to provide insights into the direction for operational tuning and future development in the model boundary layer schemes at KMA

Vapor-Deposited Tungsten Carbide Nano-Dendrites as Sulfur-Tolerant Electrocatalysts for Quantum Dot-Sensitized Solar Cells

Recent advances in optoelectronic properties of quantum dots (QDs) have led to significant improvement in QD-sensitized solar cells (QDSCs); however, for practical utilization of these devices, performance of the constituent electrocatalytic counter electrodes (CEs) needs to be further enhanced. Pt CEs are prone to severe sulfur poisoning by polysulfide redox electrolytes in QDSCs, and Cu2S CEs with state-of-the-art activity are vulnerable to light-induced degradations. In this study, for the first time, tungsten carbide (W2C) films were used as CEs for QDSCs. Instead of the conventional methods of carbide nanomaterial synthesis that involve thermal treatments in toxic/explosive atmospheres, room-temperature vapor deposition was employed for the preparation of W2C electrodes, and dendritic nanostructures with large surface areas were obtained. Although the electronic structures of Pt and W2C are highly similar, W2C was completely inert to sulfur poisoning. This led to a substantial improvement in the electrocatalytic performance for polysulfide reduction, and similar to 27% enhancement in power conversion efficiency was achieved when Pt CEs were replaced with W2C CEs in QDSCs. Moreover, QDSCs comprising W2C CEs manifested excellent photostability, and they showed performances superior to those of QDSCs comprising state-of-the-art Cu2S electrodes within 40 min of operation, without any sign of drop in efficiency. (C) 2018 The Electrochemical Societ

Influence of TiO2 Particle Size on Dye-Sensitized Solar Cells Employing an Organic Sensitizer and a Cobalt(III/II) Redox Electrolyte

Dye-sensitized solar cells (DSSCs) are highly efficient and reliable photovoltaic devices that are based on nanostructured semiconductor photoelectrodes. From their inception in 1991, colloidal TiO2 nanoparticles (NPs) with the large surface area have manifested the highest performances and the particle size of around 20 nm is generally regarded as the optimized condition. However, though there have been reports on the influences of particle sizes in conventional DSSCs employing iodide redox electrolyte, the size effects in DSSCs with the state-of-the-art cobalt electrolyte have not been investigated. In this research, systematic analyses on DSSCs with cobalt electrolytes are carried out by using various sizes of NPs (20-30 nm), and the highest performance is obtained in the case of 30 nm sized TiO2 NPs, indicating that there is a reversed power conversion efficiency trend when compared with those with the iodide counterpart. Detailed investigations on various factors - light harvesting, charge injection, dye regeneration, and charge collection - reveal that TiO2 particles with a size range of 20-30 nm do not have a notable difference in charge injection, dye regeneration, and even in light-harvesting efficiency. It is experimentally verified that the superior charge collection property is the sole origin of the higher performance, suggesting that charge collection should be prioritized for designing nanostructured TiO2 photoelectrodes for DSSCs employing cobalt redox electrolytes. © 2018 American Chemical Societ

Electrochemically synthesized nanostructured iron carbide/carbon composite as a low-cost counter electrode for dye-sensitized solar cells

Owing to the rapid increase in global energy consumption, which is currently based on fossil fuel combustion, the importance of renewable energy has become increasingly apparent. Solar energy is one of the most promising candidates to replace conventional energy sources, and various types of photovoltaic devices, including dye-sensitized solar cells, are being intensively investigated as a means for the efficient utilization of sunlight. However, the use of Pt in the counter electrodes of dye-sensitized solar cells limits their economic feasibility for practical and industrial applications. In the present study, to develop an active and economical material to replace Pt in dye-sensitized solar cells, we prepare a nanostructured iron carbide/carbon composite by electrochemical anodization of Fe foil followed by heat treatment in carbon-bearing gas atmosphere, which lead to the formation of conformal carbon shell on the surface of crystalline Fe3C. The superior catalytic properties of the iron carbide/carbon composite in the cobalt bipyridine redox electrolyte to those of Pt are confirmed by various electrochemical characterization methods. When used as the counter electrode in a dye-sensitized solar cell, the superior properties of the composite provide an 8.0% increase in power conversion efficiency compared to that achieved with a Pt counter electrode. © 2018 Elsevier B.