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A random coefficient autoregressive process is deeply investigated in which the coefficients are correlated. First we look at the existence of a strictly stationary causal solution, we give the second-order stationarity conditions and the…

Statistics Theory · Mathematics 2018-03-29 Frédéric Proïa , Marius Soltane

Autoregressive next-step prediction models have become the de-facto standard for building data-driven neural solvers to forecast time-dependent partial differential equations (PDEs). Denoise training that is closely related to diffusion…

Machine Learning · Computer Science 2025-03-31 Zijie Li , Anthony Zhou , Amir Barati Farimani

A novel adaptive control approach is proposed to solve the globally asymptotic state stabilization problem for uncertain pure-feedback nonlinear systems which can be transformed into the pseudo-affine form. The pseudo-affine pure-feedback…

Systems and Control · Computer Science 2016-09-29 Mingzhe Hou , Zongquan Deng , Guangren Duan

We present a complete analytical derivation of the equations used for stationary and nonstationary wave systems regarding resonant sound transmission and reflection described by the phenomenological Coupled-Mode Theory. We calculate the…

Classical Physics · Physics 2018-06-11 Theodoros T. Koutserimpas , Romain Fleury

In this work, we present an adjoint-based method for discovering the underlying governing partial differential equations (PDEs) given data. The idea is to consider a parameterized PDE in a general form and formulate a PDE-constrained…

Optimization and Control · Mathematics 2025-09-23 Mohsen Sadr , Tony Tohme , Kamal Youcef-Toumi

We present the development of extended diffraction tomography, a new approach to the solution of the linear seismic waveform inversion problem. This method has several appealing features, such as the use of arbitrary depth-dependent…

Geophysics · Physics 2009-05-05 R. B. Schlottmann

We consider the problem of imaging extended reflectors in terminating waveguides. We form the image by back-propagating the array response matrix projected on the waveguide's non-evanescent modes. The projection is adequately defined for…

Computational Physics · Physics 2017-11-30 Chrysoula Tsogka , Dimitrios A. Mitsoudis , Symeon Papadimitropoulos

A novel refinement measure for non-intrusive surrogate modelling of partial differential equations (PDEs) with uncertain parameters is proposed. Our approach uses an empirical interpolation procedure, where the proposed refinement measure…

Numerical Analysis · Mathematics 2019-07-10 Yous van Halder , Benjamin Sanderse , Barry Koren

We study the global well-posedness and asymptotic behavior for a semilinear damped wave equation with Neumann boundary conditions, modelling a one-dimensional linearly elastic body interacting with a rigid substrate through an adhesive…

The evolution of extended states with magnetic field and disorder intensities is investigated for 2D lattice models. The floating-up picture is revealed when the shift of the extended state, relative to the density of states, is properly…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Ana L. C. Pereira , P. A. Schulz

We propose and analyze an online algorithm for reconstructing a sequence of signals from a limited number of linear measurements. The signals are assumed sparse, with unknown support, and evolve over time according to a generic nonlinear…

Optimization and Control · Mathematics 2015-03-12 Joao F. C. Mota , Nikos Deligiannis , Aswin C. Sankaranarayanan , Volkan Cevher , Miguel R. D. Rodrigues

Embedding physical knowledge into neural network (NN) training has been a hot topic. However, when facing the complex real-world, most of the existing methods still strongly rely on the quantity and quality of observation data. Furthermore,…

Fluid Dynamics · Physics 2024-11-20 Dashan Zhang , Yuntian Chen , Shiyi Chen

A generalisation of the Lie symmetry method is applied to classify a coupled system of reaction-diffusion equations wherein the nonlinearities involve arbitrary functions in the limit case in which one equation of the pair is quasi-steady…

Mathematical Physics · Physics 2019-09-17 Roman Cherniha , Vasyl' Davydovych , John R. King

In recent years, deep learning-based image compression, particularly through generative models, has emerged as a pivotal area of research. Despite significant advancements, challenges such as diminished sharpness and quality in…

Image and Video Processing · Electrical Eng. & Systems 2024-09-18 Ryugo Morita , Hitoshi Nishimura , Ko Watanabe , Andreas Dengel , Jinjia Zhou

We investigate a system of harmonically coupled identical nonlinear constituents subject to noise in different spatial arrangements. For global coupling we find for infinitely many constituents the coexistence of several ergodic components…

adap-org · Physics 2009-10-30 R. Muller , K. Lippert , A. Kuhnel , U. Behn

We study transient patterns appearing in a class of SPDE using the framework of quasi-stationary and quasi-ergodic measures. In particular, we prove the existence and uniqueness of quasi-stationary and quasi-ergodic measures for a class of…

Probability · Mathematics 2024-06-19 Zachary P. Adams

A new technique is introduced to reconstruct a nonlinear stochastic model of the cardiorespiratory interaction. Its inferential framework uses a set of polynomial basis functions representing the nonlinear force governing the system…

Data Analysis, Statistics and Probability · Physics 2009-11-11 V. N. Smelyanskiy , D. G. Luchinsky , A. Stefanovska , P. V. E. McClintock

In recent years, autoregressive models have had a profound impact on the description of astronomical time series as the observation of a stochastic process. These methods have advantages compared with common Fourier techniques concerning…

Astrophysics · Physics 2016-01-27 M. König , J. Timmer , R. Staubert

In this paper we focus on learning optimized partial differential equation (PDE) models for image filtering. In this approach, the grey-scaled images are represented by a vector field of two real-valued functions and the image restoration…

Numerical Analysis · Mathematics 2019-07-12 Sílvia Barbeiro , Diogo Lobo

Previous raw image-based low-light image enhancement methods predominantly relied on feed-forward neural networks to learn deterministic mappings from low-light to normally-exposed images. However, they failed to capture critical…

Computer Vision and Pattern Recognition · Computer Science 2023-08-16 Yufei Wang , Yi Yu , Wenhan Yang , Lanqing Guo , Lap-Pui Chau , Alex C. Kot , Bihan Wen