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We introduce new method of optimization for finding free parameters of affine iterated function systems (IFS), which are used for fractal approximation. We provide the comparison of effectiveness of fractal and quadratic types of…

Dynamical Systems · Mathematics 2012-10-04 K. Igudesman , G. Shabernev

Extensive work has demonstrated the excellent performance of orthogonal time frequency space (OTFS) modulation in high-mobility scenarios. Time-variant wideband channel estimation serves as one of the key compositions of OTFS receivers…

Information Theory · Computer Science 2023-02-14 Xuehan Wang , Xu Shi , Jintao Wang , Jian Song

This paper deals with the numerical integration of well-posed multiscale systems of ODEs or evolutionary PDEs. As these systems appear naturally in engineering problems, time-subcycling techniques are widely used every day to improve…

Analysis of PDEs · Mathematics 2015-10-07 Guillaume Dujardin , Pauline Lafitte

Simulation-based verification algorithms can provide formal safety guarantees for nonlinear and hybrid systems. The previous algorithms rely on user provided model annotations called discrepancy function, which are crucial for computing…

Systems and Control · Computer Science 2015-02-09 Chuchu Fan , Sayan Mitra

The modulating functions method has been used for the identification of linear and nonlinear systems. In this paper, we generalize this method to the on-line identification of fractional order systems based on the Riemann-Liouville…

Numerical Analysis · Mathematics 2013-03-18 Da-Yan Liu , Taous-Meriem Laleg-Kirati , Olivier Gibaru , Wilfrid Perruquetti

We propose a method for computing bounds on output functionals of a class of time-dependent PDEs. To this end, we introduce barrier functionals for PDE systems. By defining appropriate unsafe sets and optimization problems, we formulate an…

Optimization and Control · Mathematics 2014-12-11 Mohamadreza Ahmadi , Giorgio Valmorbida , Antonis Papachristodoulou

Out-of-distribution (OOD) detection is critical for ensuring the reliability of open-world intelligent systems. Despite the notable advancements in existing OOD detection methodologies, our study identifies a significant performance drop…

Computer Vision and Pattern Recognition · Computer Science 2024-02-01 Jiuqing Dong , Yongbin Gao , Heng Zhou , Jun Cen , Yifan Yao , Sook Yoon , Park Dong Sun

It is shown that fractal dimension can be estimated seeking a solution of functional equation defined for areas of coverages of different scales. The method proposed is compared with widely known way to estimate fractal dimension via linear…

Chaotic Dynamics · Physics 2021-03-16 Dmitry Zhabin

We propose a novel method to measure the fractal dimension of a submonolayer metal adatom system grown under conditions of limited diffusivity on a surface. The method is based on measuring the specular peak attenuation of He atoms…

chem-ph · Physics 2009-10-28 D. A. Hamburger , A. T. Yinnon , R. B. Gerber

Fractal dimension is widely adopted in spatial databases and data mining, among others as a measure of dataset skewness. State-of-the-art algorithms for estimating the fractal dimension exhibit linear runtime complexity whether based on…

Databases · Computer Science 2009-05-27 Christos Attikos , Michael Doumpos

This paper presents a novel numerical optimisation method for infinite dimensional optimisation. The functional optimisation makes minimal assumptions about the functional and without any specific knowledge on the derivative of the…

Optimization and Control · Mathematics 2016-11-18 Muhammad F. Kasim , Peter A. Norreys

In this paper, we delve into the fascinating realm of fractal calculus applied to fractal sets and fractal curves. Our study includes an exploration of the method analogues of the separable method and the integrating factor technique for…

General Mathematics · Mathematics 2023-10-26 Alireza Khalili Golmankhaneh , Donatella Bongiorno

Ordinary differential equations (ODEs) are widely used to describe dynamical systems in science, but identifying parameters that explain experimental measurements is challenging. In particular, although ODEs are differentiable and would…

Machine Learning · Computer Science 2024-07-22 Jonas Beck , Nathanael Bosch , Michael Deistler , Kyra L. Kadhim , Jakob H. Macke , Philipp Hennig , Philipp Berens

The Discrete Fourier Transform (DFT) is widely utilized for signal analysis but is plagued by spectral leakage, leading to inaccuracies in signal approximation. Window functions play a crucial role in mitigating spectral leakage by…

Signal Processing · Electrical Eng. & Systems 2023-12-27 Haichao Xu , Xingpao Suo

We present the general forms of piece-wise functions on partitioned domains satisfying an intrinsic $C^0$ or $C^1$ continuity across the sub-domain boundaries. These general forms are constructed based on a strategy stemming from the theory…

Numerical Analysis · Mathematics 2024-03-12 Jielin Yang , Suchuan Dong

We describe a general operational method that can be used in the analysis of fractional initial and boundary value problems with additional analytic conditions. As an example, we derive analytic solutions of some fractional generalisation…

Analysis of PDEs · Mathematics 2013-04-04 Roberto Garra , Federico Polito

Functional error estimates are well-established tools for a posteriori error estimation and related adaptive mesh-refinement for the finite element method (FEM). The present work proposes a first functional error estimate for the boundary…

Numerical Analysis · Mathematics 2020-10-29 Stefan Kurz , Dirk Pauly , Dirk Praetorius , Sergey Repin , Daniel Sebastian

Ordinary differential equations (ODEs) are a conventional way to describe the observed dynamics of physical systems. Scientists typically hypothesize about dynamical behavior, propose a mathematical model, and compare its predictions to…

Machine Learning · Computer Science 2025-11-20 Nils Wildt , Daniel M. Tartakovsky , Sergey Oladyshkin , Wolfgang Nowak

Fourier transform methods are used to analyze functions and data sets to provide frequencies, amplitudes, and phases of underlying oscillatory components. Fast Fourier transform (FFT) methods offer speed advantages over evaluation of…

Data Analysis, Statistics and Probability · Physics 2015-07-08 Elya Courtney , Michael Courtney

Efficiently solving large-scale optimal power flow (OPF) problems is challenging due to the high dimensionality and interconnectivity of modern power systems. Decomposition methods offer a promising solution via partitioning large problems…

Optimization and Control · Mathematics 2025-12-30 Mohannad Alkhraijah , Devon Sigler , Daniel K. Molzahn