5,054 research outputs found

    Kinematic Basis of Emergent Energetics of Complex Dynamics

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    Stochastic kinematic description of a complex dynamics is shown to dictate an energetic and thermodynamic structure. An energy function φ(x)\varphi(x) emerges as the limit of the generalized, nonequilibrium free energy of a Markovian dynamics with vanishing fluctuations. In terms of the φ\nabla\varphi and its orthogonal field γ(x)φ\gamma(x)\perp\nabla\varphi, a general vector field b(x)b(x) can be decomposed into D(x)φ+γ-D(x)\nabla\varphi+\gamma, where (ω(x)γ(x))=\nabla\cdot\big(\omega(x)\gamma(x)\big)= ωD(x)φ-\nabla\omega D(x)\nabla\varphi. The matrix D(x)D(x) and scalar ω(x)\omega(x), two additional characteristics to the b(x)b(x) alone, represent the local geometry and density of states intrinsic to the statistical motion in the state space at xx. φ(x)\varphi(x) and ω(x)\omega(x) are interpreted as the emergent energy and degeneracy of the motion, with an energy balance equation dφ(x(t))/dt=γD1γbD1bd\varphi(x(t))/dt=\gamma D^{-1}\gamma-bD^{-1}b, reflecting the geometrical Dφ2+γ2=b2\|D\nabla\varphi\|^2+\|\gamma\|^2=\|b\|^2. The partition function employed in statistical mechanics and J. W. Gibbs' method of ensemble change naturally arise; a fluctuation-dissipation theorem is established via the two leading-order asymptotics of entropy production as ϵ0\epsilon\to 0. The present theory provides a mathematical basis for P. W. Anderson's emergent behavior in the hierarchical structure of complexity science.Comment: 7 page

    Bell-INGARCH Model

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    Integer-valued time series exist widely in economics, finance, biology, computer science, medicine, insurance, and many other fields. In recent years, many types of models have been proposed to model integer-valued time series data, in which the integer autoregressive model and integer-valued GARCH model are the most representative. Although there have been many results of integer-valued time series data, the parameters of integer-valued time series model structure are more complicated. This paper is dedicated to proposing a new simple integer-valued GARCH model. First, the Bell integer-valued GARCH model is given based on Bell distribution. Then, the conditional maximum likelihood estimation method is used to obtain the estimators of parameters. Later, numerical simulations confirm the finite sample properties of the estimation of unknown parameters. Finally, the model is applied in the two real examples. Compared with the existing models, the proposed model is more simple and applicable.Comment: 16 pages,4 figure

    Velocity control of longitudinal vibration ultrasonic motor using improved Elman neural network trained by CQPSO with Lévy flights

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    Longitudinally vibration ultrasonic motor (LV-USM), a canonical nonlinear system, utilizes the inverse piezoelectric effect of piezoelectric ceramic to generate the mechanical vibration within the scope of ultrasonic frequency. However, it is very difficult to establish a strict and accurate mathematical model. Hence seeking a dynamic identifier and controller for LV-USM avoiding the accurate mathematical model becomes a feasible approach. In this paper, a novel learning algorithm for dynamic recurrent Elman neural networks is present based on a particle swarm optimization (PSO) to identify and control an LV-USM. To overcome the PSO’s global search ability, Lévy flights, a kind of random walks, are imported to improve the ability of exploration rather than Brownian motion or Gauss disturbance based on Cooperative Quantum-behaved PSO (CQPSO). Thereafter, a controller is designed to perform speed control for LV-USM along with the nonlinear identification also using this kind of neural network. By discrete Lyapunov stability approach, the controller is proven to be stable theoretically and the latter trial shows its robustness of anti-noise performance. In the experiments, the numerical results illustrate that the designed identifier and controller can achieve both higher convergence precision and speed, relative to current state-of-the-art other methods. Moreover, this controller shows lower control error than other approaches while the displacement of the rotor disc in LV-USM appears more smooth and uniform

    An oxygen pool from YBaCo4O7-based oxides for soot combustion

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    Acknowledgements This work is financially supported by the National Natural Science Foundation of China (no. 21477046, 21277060 and 21547007). Open Access via RSC Gold4GoldPeer reviewe

    Time to tackle clonorchiasis in China

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    Recent publication of the global epidemiology of clonorchiasis and its relationship with cholangiocarcinoma in the journal of Infectious Diseases of Poverty has stressed the importance of Clonorchis sinensis infection. To further demonstrate its threat on public health, especially in China, comparisons between clonorchiasis and hepatitis B are made in terms of epidemiology, clinical symptoms and carcinogenicity, disability, as well as changing trends. Furthermore, major problems and prioritized researches are argued, from basic biology to intervention. Imbalance between the majority of infected population and the minority of researches in China urges for more work from Chinese scientists and international cooperation

    Tetra­aqua­tetra­kis­(4,4′-bipyridine dioxide-κO)terbium(III) octa­cyanidotungstate(V)

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    In the title compound, [Tb(C10H8N2O2)4(H2O)4][W(CN)8], both metal atoms are eight-coordinated. The TbIII ion displays a dodeca­hedral geometry, while the Wv ion exhibits a distorted square-anti­prismatic geometry. The Tb atoms are located on a special position of site symmetry -4, whereas the W atoms are located on a twofold rotation axis. The cations are linked by O—H⋯O hydrogen bonds. The title compound is isotypic with the corresponding and previously described Mo compound [Qian & Yuan (2011 ▶). Acta Cryst. E67, m845]

    Deformable Model-Driven Neural Rendering for High-Fidelity 3D Reconstruction of Human Heads Under Low-View Settings

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    Reconstructing 3D human heads in low-view settings presents technical challenges, mainly due to the pronounced risk of overfitting with limited views and high-frequency signals. To address this, we propose geometry decomposition and adopt a two-stage, coarse-to-fine training strategy, allowing for progressively capturing high-frequency geometric details. We represent 3D human heads using the zero level-set of a combined signed distance field, comprising a smooth template, a non-rigid deformation, and a high-frequency displacement field. The template captures features that are independent of both identity and expression and is co-trained with the deformation network across multiple individuals with sparse and randomly selected views. The displacement field, capturing individual-specific details, undergoes separate training for each person. Our network training does not require 3D supervision or object masks. Experimental results demonstrate the effectiveness and robustness of our geometry decomposition and two-stage training strategy. Our method outperforms existing neural rendering approaches in terms of reconstruction accuracy and novel view synthesis under low-view settings. Moreover, the pre-trained template serves a good initialization for our model when encountering unseen individuals.Comment: Accepted by ICCV2023. Visit our project page at https://github.com/xubaixinxbx/3dhead
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