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16th APCA International Conference on Automatic Control and Soft Computing, CONTROLO 2024

作者： Abreu, Zita Pinto, Raquel Simões, Rita CIDMA – Center for Research and Development in Mathematics and Applications Department of Mathematics University of Aveiro Aveiro Portugal

ISBN: (纸本)9783031817236

As maximum distance separable convolutional codes are known for their ability to achieve the generalized Singleton bound, they are highly suitable for correcting errors. Nevertheless, until now, these codes have primarily been constructed over fields of large size. This paper introduces a distinctive approach for constructing non-catastrophic MDS convolutional codes with rate 1/2 and degree 5 over the fields F11 and F13. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： convolutional codes free distance generalized Singleton bound maximum distance separable (MDS) codes non-catastrophic

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MDS Multidimensional Convolutional Codes 16th

MDS Multidimensional Convolutional Codes

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16th APCA International Conference on Automatic Control and Soft Computing, CONTROLO 2024

作者： Abreu, Zita Pinto, Raquel Simões, Rita CIDMA – Center for Research and Development in Mathematics and Applications Department of Mathematics University of Aveiro Aveiro Portugal

ISBN: (纸本)9783031817236

In this paper mD convolutional codes with finite support are considered, which are convolutional codes whose codewords have compact support indexed in Nm and take values in Fn, where F is a finite field. We establish a natural upper bound on the distance of an mD convolutional code of rate k/n and degree δ, which generalizes the Singleton bound for block codes and the generalized Singleton bound for 1D convolutional codes. We then present a particular construction of 3D convolutional codes with finite support of rate 1/n and degree δ≤2 that achieve such bound and hence have the maximum distance among all 3D convolutional codes with the same rate and degree. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Convolution

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Gradient Mittag-Leffler and strong stabilizability of time fractional diffusion processes

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Journal of Mathematical Sciences (United States) 2025年 1-12页

作者： Zitane, Hanaa Torres, Delfim F. M. Department of Mathematics Faculty of Sciences University of Abdelmalek Essaadi Tetouan B.P. 2121 Morocco Center for Research and Development in Mathematics and Applications (CIDMA) Department of Mathematics University of Aveiro Aveiro 3810-193 Portugal

This paper deals with the gradient stability and the gradient stabilizability of Caputo time fractional diffusion linear systems. First, we give sufficient conditions that allow the gradient Mittag-Leffler and strong stability, where we use a direct method based essentially on the spectral properties of the system dynamic. Moreover, we consider a class of linear and distributed feedback controls that Mittag-Leffler and strongly stabilize the state gradient. The proposed results lead to an algorithm that allows us to gradient stabilize the state of the fractional systems under consideration. Finally, we illustrate the effectiveness of the developed algorithm by a numerical example and simulations. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.

关键词： Decomposition approach Distributed controls Fractional diffusion systems Gradient stability Gradient stabilization Partial differential equations

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No-bound theorem for d=5 Myers-Perry null and timelike geodesics

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Physical Review D 2025年第6期111卷 064060-064060页

作者： João P. A. Novo Departamento de Matemática Universidade de Aveiro and Center for Research and Development in Mathematics and Applications (CIDMA) Campus de Santiago 3810-193 Aveiro Portugal

In Newtonian gravity, it is well known that Kepler’s problem admits no bound solutions in more than three spatial dimensions. This limitation extends naturally to General Relativity, where Tangherlini demonstrated that Schwarzschild black holes in higher dimensions admit no bound timelike geodesics. However, an analogous result for the rotating counterpart of the five-dimensional Tangherlini spacetime—the d=5 Myers-Perry black hole—has not yet been established. This work addresses this gap by proving that no bound timelike geodesics exist outside the event horizon of a d=5 Myers-Perry black hole, for any choice of spin parameters that avoid naked singularities. With this result in place, we further generalize to null geodesics. It is shown that radially bound null geodesics, which are absent in the four-dimensional Kerr spacetime as established by Wilkins, also cannot exist in the d=5 Myers-Perry spacetime. These results complete the geodesic analysis of this spacetime and provide a direct generalization of Wilkins’s classical result to higher dimensions. Specifically, we establish the following theorem: no radially bound timelike nor null geodesics are possible outside the event horizon of a d=5 Myers-Perry black hole, regardless of the spin configuration.

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Quality Problems Reporting: Digitalization of the processes in an Automotive Company

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Procedia Computer Science 2025年 253卷 737-744页

作者： Marco Silva Helena Alvelos Ana Raquel Xambre Department of Economics Management Industrial Engineering and Tourism (DEGEIT) University of Aveiro Aveiro 3810-193 Portugal Center for Research & Development in Mathematics and Applications (CIDMA) University of Aveiro Aveiro 3810-193 Portugal

Given the difficulty of attaining strategic competitive advantages in today’s business environment, particularly in the automotive industry, the quality of the processes involved in a production line is becoming increasingly crucial. In this context, Industry 4.0, which is closely linked to the evolution of information systems, is key, since it enables a more efficient result analysis and enhances the decision-making process for managers. Also, continuous improvement is a fundamental philosophy to help companies deal with quality issues and thus become more competitive. In this work, the developed program, that allows users to register the quality problems found in a production line, is presented. This new program contributes to maintaining an accurate record of the quality issues identified, as well as facilitates the analysis of those situations by the managers. The results observed showed that it was possible to reduce several wastes, leading to a significant impact in the organization.

关键词： Digitalization Industry 4.0 Lean Information Management

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Bifurcations in Bosonic Stars: chains and rings from spherical solutions

arXiv

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arXiv 2025年

作者： Liang, Chen Herdeiro, Carlos A.R. Radu, Eugen Departamento de Matemática Universidade de Aveiro Center for Research and Development in Mathematics and Applications CIDMA Campus de Santiago Aveiro3810-19 3 Portugal

We study the bifurcation phenomena between spherical and axisymmetric bosonic stars. By numerically solving for the zero-modes of spherical bosonic stars under specific axially symmetric perturbations, we discover that excited state spherical bosonic stars bifurcate into two types of axisymmetric bosonic stars under = 2 perturbations, with matter distributions resembling chains and rings, respectively. Meanwhile, = 4 axisymmetric perturbations lead spherical scalar bosonic stars to bifurcate into a new type of axisymmetric bosonic stars, exhibiting a mixed chain-like and ring-like matter distribution, which we refer to as gyroscope-like. Additionally, for the first time, we have constructed chains of scalar bosonic stars with 7 constituents and their corresponding ring-like scalar bosonic stars. Our results provide an explanation for the bifurcations in bosonic stars from the perspective of perturbations, and by analyzing physical quantities such as quadrupoles and energy densities we systematically discuss the impact of axisymmetric perturbations on spherical bosonic stars. © 2025, CC BY.

关键词： Spheres

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Breaking the north-south symmetry: Dyonic spinning black holes with synchronized gauged scalar hair

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Physical Review D 2025年第4期111卷 044057-044057页

作者： Pedro V. P. Cunha Departamento de Matemática da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA) Campus de Santiago 3810-193 Aveiro Portugal

We study stationary clouds of a gauged, complex scalar field on a magnetically (and possibly electrically as well) charged Kerr-Newman black hole (BH). The existence of a magnetic charge Qm promotes a north-south asymmetry of the scalar clouds. This breakdown of the clouds’ Z2-symmetry carries through to the spacetime geometry for the nonlinear continuation of the clouds: a family of magnetically charged (or dyonic) BHs with synchronized gauged scalar hair, which we construct. Their distinct phenomenology is illustrated by their imaging, exhibiting skewed shadows and lensing. Such hairy BHs could, in principle, result from the superradiant instability of magnetically charged Kerr-Newman BHs, unveiling a dynamical mechanism for creating north-south asymmetric BHs from standard Z2-symmetric electrovacuum BHs.

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A Smart Tool to Unlock Hidden Insights in Industrial Data by Leveraging EDA, LLM, Conformal Prediction, and AutoML

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Procedia Computer Science 2025年 253卷 2615-2624页

作者： Vasco Costa Diogo Costa Eugénio M. Rocha Department of Electronics Telecommunications and Informatics University of Aveiro 3810-193 Portugal Department of Mechanical Engineering University of Aveiro 3810-193 Portugal Center for Research and Development in Mathematics and Applications (CIDMA) Aveiro 3810-193 Portugal Department of Mathematics University of Aveiro 3810-193 Portugal

Rising competitiveness and client requirements make effective use of high volume and complexity real-time industrial data crucial for faster decision-making. However, this potential is hindered by a lack of smart, user-friendly analytic tools for all collaborators. Despite the proliferation of Machine Learning (ML) tools for data scientists, non-experts struggle with converting data into actionable insights and identifying profitable data science projects. A smart tool is thus proposed, allowing non-experts to perform preliminary data evaluations through profiled analysis pathways that execute predefined sets of Exploratory Data Analysis (EDA) methods and ML operations. Further assisting users, the tool solely relies on metadata attributes and textual descriptions of datasets enhanced by interaction with a Large Language Model (LLM). This paper examines profile selection stages, replacing traditional ML methods with Conformal Prediction (CP) techniques. CP identifies multiple potential prospects with statistical confidence and recognizes when correct predictions are impossible. Trials with task-labeled metadata files (derived from publicly available datasets) showed that while classic ML methods had about 80% efficiency, CP techniques improved the selection process, keeping profiling errors below 0.06 with 99% confidence. This approach enables the correct identification (with statistical confidence) of appropriate analysis profiles for data science problems, thus paving the way for more efficient data analysis tools in industrial settings, accessible to users of all skill levels.

关键词： Exploratory Data Analysis Machine Learning Conformal Prediction Large Language Models Industry 4.0

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Exact multiblack hole spacetimes in Einstein-ModMax theory

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Physical Review D 2025年第6期111卷 064046-064046页

作者： Ana Bokulić Carlos A. R. Herdeiro Department of Physics Faculty of Science University of Zagreb Bijenička cesta 32 10000 Zagreb Croatia and Departamento de Matemática Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA) Campus de Santiago 3810-193 Aveiro Portugal Departamento de Matemática Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA) Campus de Santiago 3810-193 Aveiro Portugal

Exact solutions describing multiple, electrically charged black holes (BHs) in a model of nonlinear electrodynamics (NLE) minimally coupled to Einstein’s gravity are presented. The NLE model is ModMax theory, that has attracted much attention due to its duality and conformal invariance, features shared with standard (linear) electrodynamics. In the nonextremal case, the solution has conical singularities, similarly to the multi Reissner-Nordström solution in Einstein-Maxwell theory. In the extremal case the solution is regular on and outside the event horizon; it is isometric to the Majumdar-Papapetrou solution, although the individual BHs have a nonunitary charge to mass ratio, due to screening effects. Using the ModMax electromagnetic duality invariance, magnetically charged and dyonic generalizations are also obtained. Finally, we construct multi-BH solutions with a positive cosmological constant.

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Continuous Improvement through Back-office Processes Automatization: a case study on Standardized Work Documentation

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Procedia Computer Science 2025年 253卷 1185-1194页

作者： Leonor Gonçalves Ana Moura Helena Alvelos Department of Economics Management Industrial Engineering and Tourism (DEGEIT) University of Aveiro Aveiro 3810-193 Portugal Research Unit in Governance Competitiveness and Public Policies (GOVCOPP) Department of Economics Management Industrial Engineering and Tourism University of Aveiro Aveiro 3810-193 Portugal Center for Research & Development in Mathematics and Applications (CIDMA) Department of Mathematics University of Aveiro Aveiro 3810-193 Portugal

Nowadays companies operate in a competitive environment, which means they must focus on continuously improving their processes. Eliminating waste is then crucial to ensure process efficiency, being the main target of both lean thinking concept and Toyota Production System (TPS). Another important factor to consider is the technological growth, which is beneficial to pursue and combine with continuous improvement and waste elimination. Despite TPS, Lean, and Kaizen traditionally focusing on productive processes and related activities, their fundamental principles are applicable to any part of a company, meaning that processes with the potential for automatization also include back-office processes, which rely heavily on information flows and employee knowledge. This study integrates back-office process improvement with the implementation of technology, through the development of a project based on the Continuous improvement philosophy and A3 Thinking methodology, consisting on automatizing the documentation of standardized work analysis used by an automotive company.

关键词： Automatization Back-office Documentation 5S Lean wastes

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