Article
Mathematics, Applied
Johannes Schleischitz
Summary: In this paper, we study the sumsets of classes of real numbers with specific irrationality exponents. The research shows that these sumsets are generally large, as almost every real number can be expressed as the sum of two numbers with sufficiently large irrationality exponents. The complement of these sumsets has a small Hausdorff dimension even when refined conditions on rational approximation orders are imposed.
RESULTS IN MATHEMATICS
(2023)
Article
Mathematics, Interdisciplinary Applications
Daniele Angelini, Sergio Bianchi
Summary: A Multifractional Process with Random Exponent (MPRE) is used to simulate the dynamics of log-prices in a financial market. It is shown that the Hurst-Holder exponent of the MPRE follows the fractional Ornstein-Uhlenbeck process, which describes the dynamics of the log-volatility in the Fractional Stochastic Volatility Model. Evidence is provided to demonstrate that estimation biases can generate artificial rough volatility in both surrogated and real financial data.
CHAOS SOLITONS & FRACTALS
(2023)
Article
Mathematics, Applied
Sergio Bianchi, Daniele Angelini, Augusto Pianese, Massimiliano Frezza
Summary: The study examines the roughness of the log-volatility process by testing the self-similarity of the process using the de-Lampertized realized volatility. The analysis employs a distribution-based estimator, which produces more robust results compared to scaling the individual moments of the process. The findings confirm the roughness of the log-volatility process.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2023)
Article
Mathematics, Interdisciplinary Applications
Golnaz Baghdadi, Mahmood Amiri
Summary: The study found that linear indices are almost identical among different friction states, while nonlinear features can distinguish these states. Negative Lyapunov exponent is observed during dynamic friction, while long-range dependency/memory is seen during all states.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Mathematics, Applied
Massimiliano Frezza, Sergio Bianchi, Augusto Pianese
Summary: This article identifies market inefficiency as a crucial variable in explaining the relationship between trading volume and volatility. By translating realized volatility into the corresponding pointwise Hurst-Holder exponent, the study measures the extent to which markets deviate from the martingale property, i.e. efficiency according to the Efficient Market Hypothesis. It is found that a positive contemporaneous relationship emerges when efficiency is not accounted for, but it disappears when efficiency is taken into account.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2023)
Article
Chemistry, Analytical
Igor Kotenko, Igor Saenko, Oleg Lauta, Alexander Kribel
Summary: This article discusses the construction and operation of a proactive system for protecting smart power grids against cyberattacks. The system utilizes computational intelligence methods to identify anomalies in network traffic and takes effective protection measures. Experimental results demonstrate the high efficiency of the system in detecting and predicting cyberattacks in real or near real-time.
Article
Mathematics, Applied
Danka Lucic, Tapio Rajala, Jyrki Takanen
Summary: We establish an asymptotically sharp dimension upper-bound for the boundary of bounded simply-connected planar Sobolev W-1, W-p-extension domains by using the weak mean porosity of the boundary. The sharpness of our estimate is demonstrated with examples.
ADVANCES IN CALCULUS OF VARIATIONS
(2021)
Article
Mathematics, Applied
Marcelo M. Barros, Felipe C. V. Venturelli, Luiz Bevilacqua
Summary: The concept of local persistence of increments is defined in the paper, where consecutive ups or downs in a function are quantified until a reversal. The frequency distribution of local persistences decays exponentially, leading to the definition of the local persistence coefficient to differentiate datasets. The method can be used to estimate the Hurst coefficient or fractal dimension of data functions and predict the next behavior of a complex data function.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2021)
Article
Mathematics
Efstathios K. Chrontsios Garitsis, Jeremy T. Tyson
Summary: This article investigates the distortion of Assouad dimension and the Assouad spectrum under Euclidean quasicon-formal maps. As an application, it provides a classification criterion for polynomial spirals up to quasiconformal equivalence.
BULLETIN OF THE LONDON MATHEMATICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Eugen Mircea Anitas
Summary: Recent advances in nanotechnology have allowed the fabrication of advanced materials with fractal-like geometries, where Fractional Brownian surfaces are often used to model and characterize these complex geometries. A method based on small-angle scattering technique is proposed to extract main structural parameters of surfaces/interfaces from experimental data, showing good agreement with theoretical values for various classes of Fractional Brownian surfaces.
Article
Mathematics, Applied
Subhash Chandra, Syed Abbas
Summary: In this article, we provide a rigorous study on the fractal dimension of the graph of the mixed Riemann-Liouville fractional integral for various choices of continuous functions on a rectangular region. We estimate bounds for the box dimension and the Hausdorff dimension of the graph of the mixed Riemann-Liouville fractional integral of the functions which belong to the class of continuous functions and the class of Holder continuous functions. We also discuss the cases of two-dimensional continuous functions and unbounded variational continuous functions, giving corresponding results.
NUMERICAL ALGORITHMS
(2022)
Article
Mathematics, Interdisciplinary Applications
Shima Bahramizadeh-Sajadi, Hamid Reza Katoozian, Mahtab Mehrabbeik, Alireza Baradaran-Rafii, Khosrow Jadidi, Sajad Jafari
Summary: Fractal dimension and advances in imaging technologies have been increasingly applied to interpret biological phenomena, including in the field of ophthalmology for corneal diseases. This study investigated the fractal dimension of healthy corneas and compared it to corneas of patients with keratoconus before and after intracorneal implant surgery. The Katz fractal dimension showed better discriminating ability and revealed significant differences between healthy corneas and both pre- and post-implantation topographies. The study proposes a new method to describe the curvature feature of corneal topography.
FRACTAL AND FRACTIONAL
(2022)
Article
Mathematics, Applied
Julien Barral, Stephane Seuret
Summary: In this work, Baire function spaces are constructed to address the Frisch-Parisi conjecture for functions, solving an inverse problem raised by S. Jaffard. A family of almost-doubling fully supported capacities is constructed, and each capacity is associated with a Baire function space in which typical functions have the same singularity spectrum. In the companion work, a family of heterogeneous Besov spaces is introduced and studied, providing a complete solution to the inverse problem.
JOURNAL DE MATHEMATIQUES PURES ET APPLIQUEES
(2023)
Article
Mathematics, Applied
Manuj Verma, Amit Priyadarshi, Saurabh Verma
Summary: In this article, fractal interpolation functions (FIFs) are constructed on the Sierpinski gasket (SG) using data set at the nth level. The oscillation space, L-q space, and other function spaces on SG are discussed, and conditions for FIFs belonging to these spaces are determined. The fractal dimension of the FIFs graph and the Hausdorff dimension of the invariant measure on the graph are obtained. It is proved that the FIFs have finite energy and the restrictions of the FIFs on the bottom line segment of SG are again FIFs on the bottom line.
FRACTIONAL CALCULUS AND APPLIED ANALYSIS
(2023)
Article
Materials Science, Multidisciplinary
Gulshan Kumar, Santanu Ghosh, R. P. Yadav, Udai B. Singh, A. K. Mittal, Pankaj Srivastava
Summary: The study investigated the evolution of surface morphology and formation of oxides in copper thin films annealed at various temperatures in an oxygen environment using experimental results and Higuchi's algorithm. Results showed that the Cu2O phase completely transformed into the CuO phase as the temperature increased, with the annealed copper films forming Cupreous and Cupric oxide at different temperatures. This morphological and phase evolution was analyzed through various parameters such as interface width, Hurst exponent, and fractal dimension determined by Higuchi's algorithm.
MATERIALS CHEMISTRY AND PHYSICS
(2021)
Article
Statistics & Probability
M. D. Ruiz-Medina, J. Alvarez-Liebana
STATISTICS & PROBABILITY LETTERS
(2019)
Article
Computer Science, Interdisciplinary Applications
Maria Pinto, Rosaura Fernandez-Pascual, David Caballero-Mariscal, Dora Sales, David Guerrero, Alejandro Uribe
Article
Computer Science, Interdisciplinary Applications
Maria Pinto, Rosaura Fernandez-Pascual, David Caballero-Mariscal, Dora Sales
Article
Engineering, Environmental
Antoni Torres-Signes, Maria P. Frias, Jorge Mateu, Maria D. Ruiz-Medina
Summary: The study uses a spatial curve dynamical model framework for functional prediction of counts in a spatiotemporal log-Gaussian Cox process model, incorporating wavelet-based heterogeneity analysis in time and spectral analysis in space. Model fitting is achieved through minimizing information divergence or relative entropy between data's underlying multiscale model and candidates in the spatial spectral domain. A simulation study within the family of log-Gaussian Spatial Autoregressive l(2)-valued processes demonstrates the asymptotic properties of the proposed spatial functional estimators, which are then applied to spatiotemporal prediction of respiratory disease mortality.
STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT
(2021)
Article
Computer Science, Information Systems
Maria Pinto, Rosaura Fernandez-Pascual, Carlos Lopes, Maria Luz Antunes, Tatiana Sanches
Summary: This study aimed to analyze the perceptions of belief-in-importance (BI), self-efficacy (SE), and preferred source of learning (SL) of information literacy (IL) competencies among psychology students in Spain and Portugal. The findings indicated no significant differences in students' perceptions by country, but differences were found in categories and individual competencies. Students preferred a mix of classroom and autonomous learning, and showed a lack of realization of the value of libraries. Future focus should be on enhancing students' appreciation of libraries through corresponding initiatives.
ASLIB JOURNAL OF INFORMATION MANAGEMENT
(2021)
Article
Engineering, Environmental
Antoni Torres-Signes, Maria P. Frias, Maria D. Ruiz-Medina
Summary: The article introduces a multiple objective space-time forecasting approach involving cyclical curve log-regression and multivariate time series spatial residual correlation analysis. The empirical analysis using COVID-19 mortality data demonstrates the method's advantages in prediction accuracy.
STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT
(2021)
Article
Statistics & Probability
Maria P. Frias, Antoni Torres-Signes, Maria D. Ruiz-Medina, Jorge Mateu
Summary: In this study, a new class of spatial Cox processes driven by a Hilbert-valued random log-intensity is introduced. A parametric framework in the spectral domain is adopted to estimate the spatial functional correlation structure, with strong consistency of the parametric estimator proved in the linear case. The method is applied to predict respiratory disease mortality in the Spanish Iberian Peninsula from 1980 to 2015.
Article
Geosciences, Multidisciplinary
M. D. Ruiz-Medina, D. Miranda
Summary: This study analyzes the incidence of COVID-19 in the provinces of the Spanish Communities in the Iberian Peninsula from February to October 2020. Two infinite-dimensional regression approaches, surface regression and spatial curve regression, are proposed.
SPATIAL STATISTICS
(2022)
Article
Information Science & Library Science
Maria Pinto, Dora Sales, Rosaura Fernandez-Pascual, David Caballero-Mariscal
Summary: Through a survey of undergraduate students in social sciences, the study found that students have a higher perception of personal dimension of information literacy, but have less understanding of the threshold concepts of the ACRL Framework, and responses regarding the use of ICT and mobile technologies are also diverse.
COLLEGE & RESEARCH LIBRARIES
(2021)
Article
Information Science & Library Science
Maria Pinto, Dora Sales, Rosaura Fernandez-Pascual, David Caballero-Mariscal
JOURNAL OF LIBRARIANSHIP AND INFORMATION SCIENCE
(2020)
Article
Information Science & Library Science
Maria Pinto, David Caballero, Dora Sales, Rosaura Fernandez-Pascual
JOURNAL OF LIBRARIANSHIP AND INFORMATION SCIENCE
(2020)
Article
Information Science & Library Science
Maria Pinto, Dora Sales, Rosaura Fernandez-Pascual
LIBRARY & INFORMATION SCIENCE RESEARCH
(2019)
Article
Information Science & Library Science
Maria Pinto, Rosaura Fernandez-Pascual
JOURNAL OF LIBRARIANSHIP AND INFORMATION SCIENCE
(2019)
Article
Information Science & Library Science
Maria Pinto, Jose-Antonio Gomez-Hernandez, Dora Sales, Aurora Cuevas-Cervero, Rosaura Fernandez-Pascual, David Caballero, David Guerrero-Quesada, Conrado Navalon
REVISTA IBERO-AMERICANA DE CIENCIA DA INFORMACAO
(2019)
Article
Information Science & Library Science
Maria Pinto, Rosaura Fernandez-Pascual, Francisco Javier Garcia Marco
COLLEGE & RESEARCH LIBRARIES
(2019)
Article
Engineering, Mechanical
R. Allahvirdizadeh, A. Andersson, R. Karoumi
Summary: The operational safety of high-speed trains on ballasted bridges relies on preventing ballast destabilization. This study explores the impact of epistemic uncertainties on the system using ISRA. Neglecting these uncertainties can lead to overestimation of permissible train speeds and reduced system safety.
PROBABILISTIC ENGINEERING MECHANICS
(2024)
Article
Engineering, Mechanical
Lujie Shi, Leila Khalij, Christophe Gautrelet, Chen Shi, Denis Benasciutti
Summary: This study proposes an innovative Two-phase method based on the Langlie method and the D-optimality criterion to overcome the intrinsic shortcomings of the staircase method used in estimating the fatigue limit distribution. Through simulation-based study, it is demonstrated that the proposed method improves the estimation performance for the mean and standard deviation of the fatigue limit distribution.
PROBABILISTIC ENGINEERING MECHANICS
(2024)
Article
Engineering, Mechanical
Axay Thapa, Atin Roy, Subrata Chakraborty
Summary: This article compares different metamodeling approaches for reliability analysis of tunnels to evaluate their performance. The study found that Kriging and support vector regression models perform well in estimating the reliability of underground tunnels.
PROBABILISTIC ENGINEERING MECHANICS
(2024)
Article
Engineering, Mechanical
Jiaqi Wang, Zhenzhou Lu, Lu Wang
Summary: This paper proposes an efficient method to estimate the FP-GS using reliability updating, avoiding the time-consuming double-loop structure analysis. By utilizing the likelihood function and adaptive Kriging model, the unconditional FP and all conditional FPs can be estimated simultaneously.
PROBABILISTIC ENGINEERING MECHANICS
(2024)
Article
Engineering, Mechanical
Jiaxu Li, Ming Liu, Xu Yan, Qianting Yang
Summary: Wind pressure is essential for architectural design, and this study found that using different probabilistic distribution models can improve the accuracy of reference wind pressure calculation. In the research conducted in Liaoning Province, the extreme value type III model and moment method achieved the best fit. Additionally, probability density functions for wind speed and wind direction were established for further analysis of wind pressure.
PROBABILISTIC ENGINEERING MECHANICS
(2024)
Article
Engineering, Mechanical
Yufan Cheng, Xinchen Zhuang, Tianxiang Yu
Summary: This paper proposes a time-dependent kinematic reliability analysis method that takes into account the truncated random variables and joint clearances, effectively addressing the issues of dimension variables and correlation between joint clearance variables. The proposed method transforms time-dependent reliability into time-independent reliability, greatly reducing computational complexity and obtaining upper and lower bounds of failure probability.
PROBABILISTIC ENGINEERING MECHANICS
(2024)