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15 pages, 1341 KiB

Open AccessArticle

A Model for Detecting Abnormal Elevator Passenger Behavior Based on Video Classification

by Jingsheng Lei, Wanfa Sun, Yuhao Fang, Ning Ye, Shengying Yang and Jianfeng Wu

Electronics 2024, 13(13), 2472; https://doi.org/10.3390/electronics13132472 - 24 Jun 2024

Viewed by 524

In the task of human behavior detection, video classification based on deep learning has become a prevalent technique. The existing models are limited due to an inadequate understanding of behavior characteristics, which restricts their ability to achieve more accurate recognition results. To address this issue, this paper proposes a new model, which is an improvement upon the existing PPTSM model. Specifically, our model employs a multi-scale dilated attention mechanism, which enables the model to integrate multi-scale semantic information and capture characteristic information of abnormal human behavior more effectively. Additionally, to enhance the characteristic information of human behavior, we propose a gradient flow feature information fusion module that integrates high-level semantic features with low-level detail features, enabling the network to extract more comprehensive features. Experiments conducted on an elevator passenger dataset containing four abnormal behaviors (door picking, jumping, kicking, and door blocking) show that the top-1 Acc of our model is improved by 10% compared to the PPTSM model, reaching 95%. Moreover, experiments with four publicly available datasets(UCF24, UCF101, HMDB51, and the Something-Something-v1 dataset) demonstrate that our method achieves results superior to PPTSM by 6.8%, 6.1%, 21.2%, and 3.96%, respectively. Full article

(This article belongs to the Special Issue Pattern Recognition and Machine Learning Applications, 2nd Edition)

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13 pages, 1425 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Quantum Bounds on the Generalized Lyapunov Exponents

by Silvia Pappalardi and Jorge Kurchan

Entropy 2023, 25(2), 246; https://doi.org/10.3390/e25020246 - 30 Jan 2023

Cited by 11 | Viewed by 1961

Abstract

We discuss the generalized quantum Lyapunov exponents

L_{q}

, defined from the growth rate of the powers of the square commutator. They may be related to an appropriately defined thermodynamic limit of the spectrum of the commutator, which plays the role of [...] Read more.

We discuss the generalized quantum Lyapunov exponents

L_{q}

L_{q}

via a Legendre transform. We show that such exponents obey a generalized bound to chaos due to the fluctuation–dissipation theorem, as already discussed in the literature. The bounds for larger q are actually stronger, placing a limit on the large deviations of chaotic properties. Our findings at infinite temperature are exemplified by a numerical study of the kicked top, a paradigmatic model of quantum chaos. Full article

(This article belongs to the Special Issue Quantum Chaos—Dedicated to Professor Giulio Casati on the Occasion of His 80th Birthday)

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16 pages, 5801 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Pseudoclassical Dynamics of the Kicked Top

by Zhixing Zou and Jiao Wang

Entropy 2022, 24(8), 1092; https://doi.org/10.3390/e24081092 - 9 Aug 2022

Cited by 3 | Viewed by 1815

Abstract

The kicked rotor and the kicked top are two paradigms of quantum chaos. The notions of quantum resonance and the pseudoclassical limit, developed in the study of the kicked rotor, have revealed an intriguing and unconventional aspect of classical–quantum correspondence. Here, we show that, by extending these notions to the kicked top, its rich dynamical behavior can be appreciated more thoroughly; of special interest is the entanglement entropy. In particular, the periodic synchronization between systems subject to different kicking strength can be conveniently understood and elaborated from the pseudoclassical perspective. The applicability of the suggested general pseudoclassical theory to the kicked rotor is also discussed. Full article

(This article belongs to the Special Issue Quantum Chaos—Dedicated to Professor Giulio Casati on the Occasion of His 80th Birthday)

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19 pages, 3193 KiB

Open AccessArticle

Multifractality in Quasienergy Space of Coherent States as a Signature of Quantum Chaos

by Qian Wang and Marko Robnik

Entropy 2021, 23(10), 1347; https://doi.org/10.3390/e23101347 - 15 Oct 2021

Cited by 12 | Viewed by 2524

Abstract

We present the multifractal analysis of coherent states in kicked top model by expanding them in the basis of Floquet operator eigenstates. We demonstrate the manifestation of phase space structures in the multifractal properties of coherent states. In the classical limit, the classical dynamical map can be constructed, allowing us to explore the corresponding phase space portraits and to calculate the Lyapunov exponent. By tuning the kicking strength, the system undergoes a transition from regularity to chaos. We show that the variation of multifractal dimensions of coherent states with kicking strength is able to capture the structural changes of the phase space. The onset of chaos is clearly identified by the phase-space-averaged multifractal dimensions, which are well described by random matrix theory in a strongly chaotic regime. We further investigate the probability distribution of expansion coefficients, and show that the deviation between the numerical results and the prediction of random matrix theory behaves as a reliable detector of quantum chaos. Full article

(This article belongs to the Special Issue Current Trends in Quantum Phase Transitions)

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15 pages, 3356 KiB

Open AccessArticle

Anticipating the Direction of Soccer Penalty Shots Depends on the Speed and Technique of the Kick

by Andrew H. Hunter, Sean C. Murphy, Michael J. Angilletta and Robbie S. Wilson

Sports 2018, 6(3), 73; https://doi.org/10.3390/sports6030073 - 29 Jul 2018

Cited by 4 | Viewed by 12502

Abstract

To succeed at a sport, athletes must manage the biomechanical trade-offs that constrain their performance. Here, we investigate a previously unknown trade-off in soccer: how the speed of a kick makes the outcome more predictable to an opponent. For this analysis, we focused on penalty kicks to build on previous models of factors that influence scoring. More than 700 participants completed an online survey, watching videos of penalty shots from the perspective of a goalkeeper. Participants (ranging in soccer playing experience from never played to professional) watched 60 penalty kicks, each of which was occluded at a particular moment (−0.4 s to 0.0 s) before the kicker contacted the ball. For each kick, participants had to predict shot direction toward the goal (left or right). As expected, predictions became more accurate as time of occlusion approached ball contact. However, the effect of occlusion was more pronounced when players kicked with the side of the foot than when they kicked with the top of the foot (instep). For side-foot kicks, the direction of shots was predicted more accurately for faster kicks, especially when a large portion of the kicker’s approach was presented. Given the trade-off between kicking speed and directional predictability, a penalty kicker might benefit from kicking below their maximal speed. Full article

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