Results 51 to 60 of about 1,072,173 (190)

A Deterministic Model of the Gamma Radiation at the Soil Surface–Including Soil Moisture Correction for Better Radiation Data Exploitation in Soil Mapping

Journal of Plant Nutrition and Soil Science, Volume 188, Issue 2, Page 299-311, April 2025.
ABSTRACT Background During the last decades, gamma spectrometry data have increasingly been used in soil science, for example, for mapping. However, the full data potential could not be exploited due to certain constraints, among which the insufficient representation of attenuating materials (in particular, water) in correction algorithms is the most ...
Ludger Herrmann, Georg Zimmermann
wiley   +1 more source

Non-Instantaneous Impulsive Boundary Value Problems Containing Caputo Fractional Derivative of a Function with Respect to Another Function and Riemann–Stieltjes Fractional Integral Boundary Conditions

Axioms, 2021
In the present article we study existence and uniqueness results for a new class of boundary value problems consisting by non-instantaneous impulses and Caputo fractional derivative of a function with respect to another function, supplemented with ...
Suphawat Asawasamrit, Yasintorn Thadang, Sotiris K. Ntouyas, Jessada Tariboon   +3 more
doaj   +1 more source

Option pricing in a stochastic delay volatility model

Mathematical Methods in the Applied Sciences, Volume 48, Issue 2, Page 1927-1951, 30 January 2025.
This work introduces a new stochastic volatility model with delay parameters in the volatility process, extending the Barndorff–Nielsen and Shephard model. It establishes an analytical expression for the log price characteristic function, which can be applied to price European options.
Álvaro Guinea Juliá, Raquel Caro‐Carretero   +1 more
wiley   +1 more source

Multiplicity and Uniqueness of Solution for a Class of Asymptotically Linear Fractional Differential Equation With Nonlocal Conditions

Journal of Function Spaces, Volume 2025, Issue 1, 2025.
In this paper, we study a class of asymptotically linear fractional nonlocal boundary value problems depending on the fractional derivative of lower order; the nonlinear term may be sign‐changing. By using the theory of fixed point index for asymptotically linear operators and the Banach contraction mapping principle, the multiplicity and uniqueness of
You Wu, Kemei Zhang, Yongqing Wang, Xue-Jun Xie, Richard I. Avery   +4 more
wiley   +1 more source

On the fractional Laplacian of a function with respect to another function

Mathematical Methods in the Applied Sciences, Volume 47, Issue 18, Page 14079-14110, December 2024.
The theories of fractional Laplacians and of fractional calculus with respect to functions are combined to produce, for the first time, the concept of a fractional Laplacian with respect to a bijective function. The theory is developed both in the 1‐dimensional setting and in the general n$$ n $$‐dimensional setting.
Arran Fernandez, Joel E. Restrepo, Jean‐Daniel Djida   +2 more
wiley   +1 more source

Welding defect detection with image processing on a custom small dataset: A comparative study

IET Collaborative Intelligent Manufacturing, Volume 6, Issue 4, December 2024.
This work focuses on detecting defects in welding seams using the most advanced You Only Look Once (YOLO) algorithms and transfer learning. To this end, the authors prepared a small dataset of images using manual welding and compared the performance of the YOLO v5, v6, v7, and v8 methods after two‐step training.
József Szőlősi, Béla J. Szekeres, Péter Magyar, Bán Adrián, Gábor Farkas, Mátyás Andó   +5 more
wiley   +1 more source

Solvability of a Riemann–Liouville-Type Fractional-Impulsive Differential Equation with a Riemann–Stieltjes Integral Boundary Condition

Fractal and Fractional
In this work, we address the solvability of a Riemann–Liouville-type fractional-impulsive integral boundary value problem. Under some conditions on the spectral radius corresponding to the related linear operator, we use fixed-point methods to obtain ...
Keyu Zhang, Donal O’Regan, Jiafa Xu
openalex   +2 more sources

Probabilistic analysis of a class of compartmental models formulated by random differential equations

Mathematical Methods in the Applied Sciences, Volume 47, Issue 12, Page 9493-9523, August 2024.
This paper deals with the probabilistic analysis of a class of compartmental models formulated via a system of linear differential equations with time‐dependent non‐homogeneous terms. For the sake of generality, we assume that initial conditions and rates between compartments are random variables with arbitrary distributions while the source terms ...
Vicente J. Bevia, Juan Carlos Cortés, Cristina Luisovna Pérez, Rafael‐Jacinto Villanueva   +3 more
wiley   +1 more source

Existence and Attractivity Results for Coupled Systems of Nonlinear Volterra–Stieltjes Multidelay Fractional Partial Integral Equations

Abstract and Applied Analysis, 2018
We are concerned with some existence and attractivity results of a coupled fractional Riemann–Liouville–Volterra–Stieltjes multidelay partial integral system. We prove the existence of solutions using Schauder’s fixed point theorem; then we show that the
Saïd Abbas, Mouffak Benchohra, Naima Hamidi, Gaston N’Guérékata   +3 more
doaj   +1 more source

On a lack of stability of parametrized BV solutions to rate‐independent systems with nonconvex energies and discontinuous loads

ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik, Volume 104, Issue 7, July 2024.
Abstract We consider a rate‐independent system with nonconvex energy under discontinuous external loading. The underlying space is finite‐dimensional and the loads are functions in BV([0,T];Rd)$BV([0,T];\mathbb {R}^d)$. We investigate the stability of various solution concepts w.r.t.
Merlin Andreia, Christian Meyer
wiley   +1 more source