190 research outputs found
Effect of secondary oxidation of pre-oxidized coal on early warning value for spontaneous combustion of coal
The indicative ability of a gas indicator for the spontaneous combustion of coal is affected by the secondary oxidation of oxidized coal, from old goafs, entering a new goaf through air leakages. This phenomenon can affect the accuracy of early warning systems regarding the spontaneous combustion of coal in a goaf. In this research, three kinds of coal were selected to carry out a spontaneous combustion simulation experiment in which a temperature-programmed experimental device was used to analyze the behavior of the index gas towards raw coal and oxidized coal, for which the latter was oxidized at 70 ¿C, 90 ¿C, 130 ¿C, and 150 ¿C. The results show that the chain alkane ratio in the secondary oxidation process and the trends of oxygen, CO, and C2H4 concentrations are the same as those in the primary oxidation process. On the other hand, the temperature at which C2H4 initially appears, during secondary oxidation, is lower than in primary oxidation. The CO produced in the early stage of secondary oxidation is greater than the CO produced, at the same temperature, in primary oxidation. In this regard, the usage of C2H4 concentration as an indicator with which to judge the occurrence of the spontaneous combustion of coal would allow for an earlier response. In the secondary oxidation process, the temperature of the extreme value of the alkene ratio appears higher than in primary oxidation. The presence of a higher pre-oxidation temperature and a higher proportion of secondary oxidation gas will affect an indicator’s judgement when the primary oxidation enters the severe oxidation stage. The gas produced by secondary oxidation will affect the early warning of the spontaneous combustion of coal in the coal mine goaf, which should be considered in the establishment of an early warning system.This work was supported by the National Natural Science Foundation of China [52074285].Peer ReviewedObjectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement EconòmicObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version
WMFormer++: Nested Transformer for Visible Watermark Removal via Implict Joint Learning
Watermarking serves as a widely adopted approach to safeguard media
copyright. In parallel, the research focus has extended to watermark removal
techniques, offering an adversarial means to enhance watermark robustness and
foster advancements in the watermarking field. Existing watermark removal
methods mainly rely on UNet with task-specific decoder branches--one for
watermark localization and the other for background image restoration. However,
watermark localization and background restoration are not isolated tasks;
precise watermark localization inherently implies regions necessitating
restoration, and the background restoration process contributes to more
accurate watermark localization. To holistically integrate information from
both branches, we introduce an implicit joint learning paradigm. This empowers
the network to autonomously navigate the flow of information between implicit
branches through a gate mechanism. Furthermore, we employ cross-channel
attention to facilitate local detail restoration and holistic structural
comprehension, while harnessing nested structures to integrate multi-scale
information. Extensive experiments are conducted on various challenging
benchmarks to validate the effectiveness of our proposed method. The results
demonstrate our approach's remarkable superiority, surpassing existing
state-of-the-art methods by a large margin
DocStormer: Revitalizing Multi-Degraded Colored Document Images to Pristine PDF
For capturing colored document images, e.g. posters and magazines, it is
common that multiple degradations such as shadows, wrinkles, etc., are
simultaneously introduced due to external factors. Restoring multi-degraded
colored document images is a great challenge, yet overlooked, as most existing
algorithms focus on enhancing color-ignored document images via binarization.
Thus, we propose DocStormer, a novel algorithm designed to restore
multi-degraded colored documents to their potential pristine PDF. The
contributions are: firstly, we propose a "Perceive-then-Restore" paradigm with
a reinforced transformer block, which more effectively encodes and utilizes the
distribution of degradations. Secondly, we are the first to utilize GAN and
pristine PDF magazine images to narrow the distribution gap between the
enhanced results and PDF images, in pursuit of less degradation and better
visual quality. Thirdly, we propose a non-parametric strategy, PFILI, which
enables a smaller training scale and larger testing resolutions with acceptable
detail trade-off, while saving memory and inference time. Fourthly, we are the
first to propose a novel Multi-Degraded Colored Document image Enhancing
dataset, named MD-CDE, for both training and evaluation. Experimental results
show that the DocStormer exhibits superior performance, capable of revitalizing
multi-degraded colored documents into their potential pristine digital
versions, which fills the current academic gap from the perspective of method,
data, and task
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