478 research outputs found

    TempEE: Temporal-Spatial Parallel Transformer for Radar Echo Extrapolation Beyond Auto-Regression

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    Meteorological radar reflectivity data (i.e. radar echo) significantly influences precipitation prediction. It can facilitate accurate and expeditious forecasting of short-term heavy rainfall bypassing the need for complex Numerical Weather Prediction (NWP) models. In comparison to conventional models, Deep Learning (DL)-based radar echo extrapolation algorithms exhibit higher effectiveness and efficiency. Nevertheless, the development of reliable and generalized echo extrapolation algorithm is impeded by three primary challenges: cumulative error spreading, imprecise representation of sparsely distributed echoes, and inaccurate description of non-stationary motion processes. To tackle these challenges, this paper proposes a novel radar echo extrapolation algorithm called Temporal-Spatial Parallel Transformer, referred to as TempEE. TempEE avoids using auto-regression and instead employs a one-step forward strategy to prevent cumulative error spreading during the extrapolation process. Additionally, we propose the incorporation of a Multi-level Temporal-Spatial Attention mechanism to improve the algorithm's capability of capturing both global and local information while emphasizing task-related regions, including sparse echo representations, in an efficient manner. Furthermore, the algorithm extracts spatio-temporal representations from continuous echo images using a parallel encoder to model the non-stationary motion process for echo extrapolation. The superiority of our TempEE has been demonstrated in the context of the classic radar echo extrapolation task, utilizing a real-world dataset. Extensive experiments have further validated the efficacy and indispensability of various components within TempEE.Comment: Have been accepted by IEEE Transactions on Geoscience and Remote Sensing, see https://ieeexplore.ieee.org/document/1023874

    MASK-CNN-Transformer For Real-Time Multi-Label Weather Recognition

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    Weather recognition is an essential support for many practical life applications, including traffic safety, environment, and meteorology. However, many existing related works cannot comprehensively describe weather conditions due to their complex co-occurrence dependencies. This paper proposes a novel multi-label weather recognition model considering these dependencies. The proposed model called MASK-Convolutional Neural Network-Transformer (MASK-CT) is based on the Transformer, the convolutional process, and the MASK mechanism. The model employs multiple convolutional layers to extract features from weather images and a Transformer encoder to calculate the probability of each weather condition based on the extracted features. To improve the generalization ability of MASK-CT, a MASK mechanism is used during the training phase. The effect of the MASK mechanism is explored and discussed. The Mask mechanism randomly withholds some information from one-pair training instances (one image and its corresponding label). There are two types of MASK methods. Specifically, MASK-I is designed and deployed on the image before feeding it into the weather feature extractor and MASK-II is applied to the image label. The Transformer encoder is then utilized on the randomly masked image features and labels. The experimental results from various real-world weather recognition datasets demonstrate that the proposed MASK-CT model outperforms state-of-the-art methods. Furthermore, the high-speed dynamic real-time weather recognition capability of the MASK-CT is evaluated.Comment: Under Revie

    Open quantum dynamics of single-photon optomechanical devices

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    We study the quantum dynamics of a Michelson interferometer with Fabry-Perot cavity arms and one movable end mirror, and driven by a single photon --- an optomechanical device previously studied by Marshall et al. as a device that searches for gravity decoherence. We obtain an exact analytical solution for the system's quantum mechanical equations of motion, including details about the exchange of the single photon between the cavity mode and the external continuum. The resulting time evolution of the interferometer's fringe visibility displays interesting new features when the incoming photon's frequency uncertainty is narrower or comparable to the cavity's line width --- only in the limiting case of much broader-band photon does the result return to that of Marshall et al., but in this case the photon is not very likely to enter the cavity and interact with the mirror, making the experiment less efficient and more susceptible to imperfections. In addition, we show that in the strong-coupling regime, by engineering the incoming photon's wave function, it is possible to prepare the movable mirror into an arbitrary quantum state of a multi-dimensional Hilbert space.Comment: 14 pages and 9 figures. Comments are welcom

    Effect of Physical Exercise on Life Satisfaction of Chinese Primary Students: The Chain Mediating Role of Self-Confidence and Resilience

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    Life satisfaction is an overall cognitive evaluation of an individual\u27s living condition for the most of time or over a certain period of time according to the standard of one’s own choice. It is an important psychological variable in the developmental stage of children and adolescents. Some studies had shown that life satisfaction was closely related to children\u27s and adolescents\u27 mental health levels, including their emotional and behavioral conditions. However, the Blue Book for Children: China Children\u27s Development Report (2020) published by China Children\u27s Center stated that Chinese students did not fare well in terms of life satisfaction. Previous studies had indicated that physical exercise was an important factor that had a positive effect on life satisfaction, as well as on self-confidence and resilience. Also, there is a correlation between self-confidence, resilience, and life satisfaction. Nonetheless, few studies have researched the role of self-confidence and resilience in the impact of physical exercise on the life satisfaction of primary school students. To explore the mediating role of self-confidence and resilience between physical exercise and life satisfaction, in order to provide a theoretical basis and practical guidance for how to effectively promote life satisfaction and psychological well-being of primary school students in the practice of physical exercise. Group measurements of 1009 students (519 boys and 490 girls; 576 fifth graders and 433 sixth graders) are carried out by using the Scale of Physical Exercise Level, Children and Adolescent Self-Confidence Scale, Children and Adolescent Life Satisfaction Scale, and Adolescent Resilience Scale, and Structural Equation Model and Bootstrap are used to analyze the mediating effect of self-confidence and resilience. The results reveal that there is a positive correlation between physical exercise and life satisfaction (r=0.218), but the effect on life satisfaction is not significant (P=0.516); the indirect effect of physical exercise on life satisfaction consists of two paths: physical exercise to self-confidence to life satisfaction (95% CI: 0.128,0.267); physical exercise to self-confidence to resilience to life satisfaction (95% CI:0.109,0.209). It is concluded that physical exercise has an indirect but significant effect on primary school students\u27 life satisfaction--the independent mediating effect of self-confidence and the chain mediation effect of self-confidence and resilience. The study further confirms that physical exercise can promote students\u27 self-confidence levels and the formation of tenacious psychological quality, thus improving their life satisfaction levels. Therefore, society, schools and families should pay close attention to the positive effects of physical exercise on primary school students’ emotional and behavioral conditions

    Brownian Thermal Noise in Multilayer Coated Mirrors

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    We analyze the Brownian thermal noise of a multi-layer dielectric coating, used in high-precision optical measurements including interferometric gravitational-wave detectors. We assume the coating material to be isotropic, and therefore study thermal noises arising from shear and bulk losses of the coating materials. We show that coating noise arises not only from layer thickness fluctuations, but also from fluctuations of the interface between the coating and substrate, driven by internal fluctuating stresses of the coating. In addition, the non-zero photoeleastic coefficients of the thin films modifies the influence of the thermal noise on the laser field. The thickness fluctuations of different layers are statistically independent, however, there exists a finite coherence between layers and the substrate-coating interface. Taking into account uncertainties in material parameters, we show that significant uncertainties still exist in estimating coating Brownian noise.Comment: 26 pages, 18 figure
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