Journal Description
Axioms
Axioms
is an international, peer-reviewed, open access journal of mathematics, mathematical logic and mathematical physics, published monthly online by MDPI. The International Fuzzy Systems Association (IFSA), Union of Slovak Mathematicians and Physicists (JSMF) and Eurekas Community are affiliated with Axioms and their members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High visibility: indexed within SCIE (Web of Science), dblp, and other databases.
- Journal Rank: JCR - Q2 (Mathematics, Applied)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 21.6 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the first half of 2026).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Logics.
- Journal Cluster of Mathematics and Its Applications: AppliedMath, Axioms, Computation, Fractal and Fractional, Geometry, International Journal of Topology, Logics, Mathematics and Symmetry.
Impact Factor:
1.5 (2025);
5-Year Impact Factor:
1.5 (2025)
Latest Articles
A Sobolev–Information Perspective on Derivative-Observation-Augmented PINNs for Parameter Identification of Second-Order Dynamical Systems
Axioms 2026, 15(8), 602; https://doi.org/10.3390/axioms15080602 (registering DOI) - 9 Aug 2026
Abstract
Identifying parameters of dynamical systems from sparse measurements is a core task in structural health monitoring and vibration engineering. For second-order oscillators, standard physics-informed neural networks (PINNs) struggle because different parameter values can produce nearly identical displacement records, making the inverse problem ill-posed.
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Identifying parameters of dynamical systems from sparse measurements is a core task in structural health monitoring and vibration engineering. For second-order oscillators, standard physics-informed neural networks (PINNs) struggle because different parameter values can produce nearly identical displacement records, making the inverse problem ill-posed. We propose the derivative-observation-augmented PINN (D-PINN), which incorporates velocity measurements into the training loss to resolve this degeneracy. Three theoretical results support the method: a Sobolev-type inequality proves that constraining the velocity error automatically bounds the displacement error; a Fisher information analysis shows that velocity observations increase the information available for parameter estimation; and a residual-based estimate bounds the parameter error in terms of the solution accuracy and its derivatives. Experiments on linear, forced near-resonance, and Duffing oscillators (10 random seeds, 20,000 epochs) show that D-PINN reduces the damping coefficient relative error from 40% to 11.7% without any parameter prior. With a weak prior ( , a 20% deviation from the true value 4.0), the error drops further to 2.1%, a 19-fold improvement over standard PINN. We also analyze sensitivity to prior quality, derivative observation source, and measurement noise, and identify scenarios where derivative observations do not improve displacement fitting.
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(This article belongs to the Special Issue Application of Machine Learning and Optimization Methods in Engineering Mathematics, 2nd Edition)
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Deep Learning for Solving Integral Equations: A Problem-Oriented Review with an Axiomatic Perspective
by
Zhiyuan Ren, Ruilong Yu, Yi Zeng and Shijie Zhou
Axioms 2026, 15(8), 601; https://doi.org/10.3390/axioms15080601 (registering DOI) - 9 Aug 2026
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This review surveys recent deep learning approaches for solving integral equations, categorizing them into three methodological families: physics-informed embedding, spectral/topological acceleration, and hybrid symbolic–numeric frameworks. The main findings are threefold. First, these methods achieve promising empirical accuracy in oscillatory, high-dimensional, and singular-kernel settings,
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This review surveys recent deep learning approaches for solving integral equations, categorizing them into three methodological families: physics-informed embedding, spectral/topological acceleration, and hybrid symbolic–numeric frameworks. The main findings are threefold. First, these methods achieve promising empirical accuracy in oscillatory, high-dimensional, and singular-kernel settings, yet their theoretical foundations remain largely incomplete. Second, from an axiomatic perspective, most approaches lack rigorous guarantees of convergence, stability, and spectral consistency; we formulate five testable propositions that a complete theory should satisfy. Third, we identify five specific unresolved theoretical questions and outline a focused research agenda toward a mathematically rigorous theory of neural operator approximation for integral equations. The novelty of this review lies in its dual computational–axiomatic evaluation and its provision of a structured, problem-oriented framework for future investigations.
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Open AccessArticle
Another Simple Proof of the Close Connection of SQS(10) and GQ(2,2)
by
Stefano Innamorati
Axioms 2026, 15(8), 600; https://doi.org/10.3390/axioms15080600 (registering DOI) - 9 Aug 2026
Abstract
Symmetry plays a key role in identifying the close connection between different finite incidence structures. In this paper, by studying the properties of points not belonging to an elliptic quadric of PG(3,3), a short demonstration is given of the close connection between the
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Symmetry plays a key role in identifying the close connection between different finite incidence structures. In this paper, by studying the properties of points not belonging to an elliptic quadric of PG(3,3), a short demonstration is given of the close connection between the Steiner Quadruple system SQS(10) and the Cremona–Richmond configuration.
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(This article belongs to the Special Issue Graph Invariants and Their Applications)
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Open AccessFeature PaperArticle
by
Nicholay S. Tonchev and Daniel Dantchev
Axioms 2026, 15(8), 599; https://doi.org/10.3390/axioms15080599 (registering DOI) - 8 Aug 2026
Abstract
Using the properties of , the general linear group of invertible real matrices, we investigate random fields of spin variables on finite one-dimensional rings with a unit cell of sites. The
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Using the properties of , the general linear group of invertible real matrices, we investigate random fields of spin variables on finite one-dimensional rings with a unit cell of sites. The interaction parameters are assumed to be periodic with period p. The cases and recover the one-dimensional and alternating Ising models, respectively. The couplings between adjacent spins may be ferromagnetic (positive) or antiferromagnetic (negative). Utilising the recurrence relations of the Chebyshev polynomials and a bijection between the number of spins and the polynomial index, we derive explicit formulae well suited to the finite-size analysis of the partition functions, free energy, and specific heat of both models. We show that, for the ( ) case, the specific heat exhibits a double-Schottky anomaly whenever the characteristic exchange energy scales are sufficiently separated. We prove that this double-peak structure originates from the coexistence of distinct energy scales induced by the periodic modulation of the coupling signs and characterise its dependence on the model parameters. We demonstrate that the universality hypothesis in critical Casimir force theory remarkably holds without requiring small fields or large interaction parameters, suggesting a form of “hyper-universal” behaviour valid for arbitrary model parameters.
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(This article belongs to the Special Issue Advances in Linear Algebra with Applications, 2nd Edition)
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Open AccessArticle
Trajectory Tracking Control of an Off-Axis Tractor-Trailer Wheeled Mobile System with Passive Steering
by
Xiangrong Wen, Danhong Chen and Yusheng Zhou
Axioms 2026, 15(8), 598; https://doi.org/10.3390/axioms15080598 (registering DOI) - 8 Aug 2026
Abstract
This paper investigates the system modeling and trajectory tracking control problem of an off-axis tractor-trailer wheeled mobile system and proposes a control strategy based on an integral sliding surface and a super-twisting algorithm. First, the motion relationship between the tractor and trailer is
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This paper investigates the system modeling and trajectory tracking control problem of an off-axis tractor-trailer wheeled mobile system and proposes a control strategy based on an integral sliding surface and a super-twisting algorithm. First, the motion relationship between the tractor and trailer is derived based on their geometric configuration, and the kinematic and dynamic models of the off-axis tractor-trailer wheeled mobile system with a passive steering angle are established. Then, a composite controller is designed by integrating the integral sliding surface with the super-twisting algorithm to achieve accurate tracking of the desired trajectory. During the controller design process, the desired trajectory is reconstructed as a curvature-consistent dynamic tracking target. Under this dynamic tracking target, the curvature deviation depends only on the yaw-rate error and is decoupled from longitudinal velocity disturbances, thereby improving trajectory tracking accuracy. Finally, numerical simulations are conducted to validate the effectiveness and generality of the proposed control strategy under three typical reference trajectories, including cycloidal, S-shaped, and circular trajectories. Comparisons with PID and feedback linearization control methods are also performed. The simulation results demonstrate that the off-axis tractor-trailer wheeled mobile system can closely follow the desired trajectories and exhibits satisfactory robustness.
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(This article belongs to the Topic Nonlinear Phenomena, Chaos, Control and Applications to Engineering and Science and Experimental Aspects of Complex Systems, 2nd Edition)
Open AccessArticle
Classical and Bayesian Parameter Estimation for Generalised Exponential Competing Risks Models Under Improved Adaptive Type-II Progressive Censoring
by
Hana N. Alqifari
Axioms 2026, 15(8), 597; https://doi.org/10.3390/axioms15080597 - 7 Aug 2026
Abstract
Competing-risks models play an important role in reliability and survival analysis because failures often arise from several latent causes acting simultaneously. In this paper, we study a two-cause independent competing-risks model in which the latent lifetimes follow the generalised exponential distribution under the
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Competing-risks models play an important role in reliability and survival analysis because failures often arise from several latent causes acting simultaneously. In this paper, we study a two-cause independent competing-risks model in which the latent lifetimes follow the generalised exponential distribution under the improved adaptive Type-II progressive censoring scheme. The proposed framework aims to estimate the model parameters together with the reliability and hazard-rate functions using both classical and Bayesian inference. The frequentist analysis develops maximum likelihood estimators and approximate confidence intervals based on asymptotic theory, whereas the Bayesian analysis employs independent Gamma priors, squared-error loss, and a Metropolis–Hastings algorithm to obtain posterior estimates and highest posterior density credible intervals. An extensive Monte Carlo simulation study is conducted to investigate their finite-sample performance under different censoring schemes, threshold settings, and sample sizes. Finally, two real competing-risks datasets are analysed to illustrate the practical applicability of the proposed methodology and to demonstrate that the generalised exponential competing-risks model provides a competitive alternative for reliability and survival data analysis.
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(This article belongs to the Special Issue Probability, Statistics and Estimations, 3rd Edition)
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Open AccessArticle
A Measure-Theoretic Formulation of Hybrid Systems Beyond Zeno Time
by
Robert Vrabel
Axioms 2026, 15(8), 596; https://doi.org/10.3390/axioms15080596 - 7 Aug 2026
Abstract
Hybrid dynamical systems may exhibit Zeno behavior, where infinitely many discrete transitions occur in finite time, leading to a loss of well-posedness of trajectories beyond the accumulation point. This paper develops a measure-theoretic formulation of hybrid dynamics by representing discrete transitions through finite
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Hybrid dynamical systems may exhibit Zeno behavior, where infinitely many discrete transitions occur in finite time, leading to a loss of well-posedness of trajectories beyond the accumulation point. This paper develops a measure-theoretic formulation of hybrid dynamics by representing discrete transitions through finite vector-valued Radon measures and recasting the system as a measure differential inclusion. Within this framework, we establish a closure result for extended hybrid solutions in the space of functions of bounded variation and derive an existence result under suitable approximation assumptions. We also prove consistency with classical hybrid trajectories in the absence of Zeno behavior and characterize the state at the Zeno time as the left limit of the hybrid evolution, together with any additional vector atom deliberately assigned at the accumulation time. The proposed formulation provides a natural basis for continuation beyond the accumulation point and allows Lyapunov-based stability properties to be formulated directly at the level of the measure-driven dynamics. A central feature of the approach is that infinitely many discrete transitions with finite total variation of the jump increments are encoded by a finite vector-valued atomic measure whose atoms may accumulate at the Zeno time. An additional vector atom at the Zeno time may be introduced as a lumped effective jump; however, such an atom should be understood as a modeling choice, not as an automatic consequence of the jump sequence. The results are illustrated on an event-triggered control system exhibiting Zeno accumulation.
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(This article belongs to the Special Issue Differential Equations and Dynamical Systems: Theory and Applications, 2nd Edition)
Open AccessArticle
Legendre Polynomials and an Inequality for a Combinatorial Sum
by
Horst Alzer and Hans W. Volkmer
Axioms 2026, 15(8), 595; https://doi.org/10.3390/axioms15080595 - 7 Aug 2026
Abstract
Let be the Legendre polynomial of degree n. We use an estimate for the ultraspherical polynomials and a gamma function inequality to prove that
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Let be the Legendre polynomial of degree n. We use an estimate for the ultraspherical polynomials and a gamma function inequality to prove that and we apply this result to obtain the combinatorial inequality The factor given in both inequalities is the best possible.
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(This article belongs to the Section Mathematical Analysis)
Open AccessArticle
The Dynamic String-Averaging Method for Inverse Strongly-Monotone Operators with Summable Errors
by
Alexander J. Zaslavski
Axioms 2026, 15(8), 594; https://doi.org/10.3390/axioms15080594 - 7 Aug 2026
Abstract
In the work by W. Takahashi and M. Toyoda (2003) it was introduced and studied an iterative process for solving a variational inequality problem which is induced by a inverse strongly-monotone mapping. They showed the weak convergence of the iteration process. Recently we
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In the work by W. Takahashi and M. Toyoda (2003) it was introduced and studied an iterative process for solving a variational inequality problem which is induced by a inverse strongly-monotone mapping. They showed the weak convergence of the iteration process. Recently we established that most of exact iterates of the same iterative process are approximate solutions of the variational inequality. In the present work we use the dynamic string-averaging algorithm for finding a common solution of a finite family of variational inequality problems, generated by inverse strongly-monotone mappings, and a finite family of fixed point problems. We study this algorithm in the presence of summable computational errors. It is shown that the cardinality of the set of iterates which are not approximate solutions is finite and does not exceed a certain constant which is calculated.
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(This article belongs to the Special Issue Applications in Functional Analysis)
Open AccessArticle
A Truncated-Kernel Mollification Method for the Cauchy Problem of the Modified Helmholtz Equation
by
Huilin Xu, Fanli Xu and Baoxia Wang
Axioms 2026, 15(8), 593; https://doi.org/10.3390/axioms15080593 - 5 Aug 2026
Abstract
This paper addresses the Cauchy problem for the multi-dimensional modified Helmholtz equation, a classical and severely ill-posed problem. A truncated-kernel mollification method is proposed as an effective regularization approach. Both the a priori and a posteriori regularization parameter choice strategies are examined, and
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This paper addresses the Cauchy problem for the multi-dimensional modified Helmholtz equation, a classical and severely ill-posed problem. A truncated-kernel mollification method is proposed as an effective regularization approach. Both the a priori and a posteriori regularization parameter choice strategies are examined, and the associated error estimates and convergence rates of the regularized solutions are established. The practical viability and effectiveness of the method are further validated through numerical experiments.
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(This article belongs to the Special Issue Theory and Applications: Numerical Analysis)
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A Proportional-Arithmetic Framework for Fourier Analysis on the Positive Real Line
by
Carlos M. Cruz-Rodas, Marlon M. López-Flores and William Campillay-Llanos
Axioms 2026, 15(8), 592; https://doi.org/10.3390/axioms15080592 - 5 Aug 2026
Abstract
This paper develops a Fourier framework internal to proportional arithmetic on the positive real line. We construct the corresponding complex scalar field, differential and integral operators, oscillatory kernel, Fourier transform, and proportional function spaces. A correspondence theorem proves that the representative of the
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This paper develops a Fourier framework internal to proportional arithmetic on the positive real line. We construct the corresponding complex scalar field, differential and integral operators, oscillatory kernel, Fourier transform, and proportional function spaces. A correspondence theorem proves that the representative of the proportional transform is the classical Fourier transform under the logarithmic identification. Consequently, inversion, Plancherel, convolution, Schwartz invariance, and Sobolev characterizations follow by transport. We establish the exact relation with Fourier analysis on the multiplicative group and with the Mellin transform on the imaginary axis. Model resolvent and heat equations illustrate the operational calculus, while a scale-localized profile shows how spectral modulus and phase encode log-scale width and preferred scale. The construction is therefore a systematic proportional-arithmetic realization of classical harmonic analysis, rather than an analytically independent Fourier theory.
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(This article belongs to the Section Mathematical Analysis)
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Analytical Study of Impulsive Hilfer-Type Fractional p-Laplacian Problems Using Neural Networks and Finite-Difference Methods
by
Rahman Ullah Khan, Ioannis K. Argyros, Taha Radwan and Yousif Altayeb
Axioms 2026, 15(8), 591; https://doi.org/10.3390/axioms15080591 - 5 Aug 2026
Abstract
We consider an impulsive BVP related to the Hilfer fractional derivatives and the nonlinear p-Laplacian operator. The type parameter is kept unchanged in the formulation, and the Riemann–Liouville and Caputo cases are obtained as limiting
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We consider an impulsive BVP related to the Hilfer fractional derivatives and the nonlinear p-Laplacian operator. The type parameter is kept unchanged in the formulation, and the Riemann–Liouville and Caputo cases are obtained as limiting cases of the formulation, not as separate cases. The variational functional is then built by adding the point-impulse contribution to the distributed potential and the use of an appropriate space of the Hilfer fractional derivative. Using variants of the fountain theorem, we prove the existence of two infinite sequences of weak solutions, one of which is of unbounded energy and another of which is of small energy and tends to zero from below. The weak residual based stability analysis is further developed, and local generalized Hyers–Ulam and Hyers–Ulam–Rassias stability estimates are obtained. Because of multiplicity of solutions, a uniqueness-based argument for stability, Ulam’s approach, is not possible and stability is instead achieved by providing residual-based arguments.The assumptions are verified through illustrative examples. Lastly, we examine the convergence behavior, residual decay, and effect of the Hilfer type parameter in conjunction with a Hilfer-type parameter neural surrogate with boundary constraints based on a discrete Hilfer scheme. The study, in general, proves a link between the solution multiplicity, residual stability, and the numerical realization in one impulsive fractional p-Laplacian framework.
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(This article belongs to the Special Issue Nonlinear Fractional Differential Equations: Theory and Applications)
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Open AccessArticle
A Unified Hybrid Estimation Strategy Using Multiple Auxiliary Transformations in Systematic Sampling with Simulation and Real-Life Applications
by
Fatimah A. Almulhim, Hassan M. Aljohani and Umer Daraz
Axioms 2026, 15(8), 590; https://doi.org/10.3390/axioms15080590 - 5 Aug 2026
Abstract
Estimating the finite population mean under systematic sampling becomes challenging when auxiliary information is nonlinear, skewed, or structurally complex, as conventional linear estimators often lose efficiency. This study proposes a new class of weighted hybrid estimators that combine harmonic and geometric transformations of
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Estimating the finite population mean under systematic sampling becomes challenging when auxiliary information is nonlinear, skewed, or structurally complex, as conventional linear estimators often lose efficiency. This study proposes a new class of weighted hybrid estimators that combine harmonic and geometric transformations of the auxiliary variable. The proposed approach is designed to capture nonlinear relationships while handling skewed data and reducing sensitivity to extreme observations. Expressions for bias and mean squared error are derived, and optimal weights are obtained by minimizing the mean squared error. The theoretical results indicate that the proposed estimators are more efficient than traditional ratio, product, regression, and exponential-type estimators. A simulation study further confirms their improved performance across various population structures, correlation levels, and sampling fractions, with notable improvements in skewed and nonlinear settings. The proposed class provides a flexible and reliable alternative for practical applications in systematic sampling.
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(This article belongs to the Section Mathematical Analysis)
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Open AccessEditorial
Theory and Application of Integral Inequalities, 2nd Edition
by
Loredana Ciurdariu
Axioms 2026, 15(8), 589; https://doi.org/10.3390/axioms15080589 - 5 Aug 2026
Abstract
In this Editorial, we present “Theory and Application of Integral Inequalities, 2nd Edition” a Special Issue of the Journal Axioms [...]
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(This article belongs to the Special Issue Theory and Application of Integral Inequalities, 2nd Edition)
Open AccessArticle
Acceptance Sampling Plans for Exponential- and Weibull-Distributed Lifetimes Under the Group Sampling Framework
by
Ching-Ho Yen, Kuen-Suan Chen, Mou-Yuan Liao, Chun-Min Yu and Ting Zhou
Axioms 2026, 15(8), 588; https://doi.org/10.3390/axioms15080588 - 4 Aug 2026
Abstract
Product lifetime is a critical quality characteristic of electronic products. Among various lifetime models, the Weibull distribution is one of the most flexible and widely used distributions in reliability analysis because it can describe different failure rate patterns through its shape parameter. In
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Product lifetime is a critical quality characteristic of electronic products. Among various lifetime models, the Weibull distribution is one of the most flexible and widely used distributions in reliability analysis because it can describe different failure rate patterns through its shape parameter. In this study, the Weibull distribution is treated as the primary lifetime model, while the exponential distribution is included as a simpler benchmark model and as a special case of the Weibull distribution with shape parameter m = 1. Based on the lifetime performance index, this research applies the group sampling concept to design two lifetime acceptance sampling plans under these lifetime distributions. The optimal sampling plan parameters of the lifetime acceptance sampling plans are determined by minimizing the number of groups while satisfying the two-point principle of the operating characteristic curve. For practical purposes, the parameters of the proposed plan are tabulated for some combinations of quality levels with commonly used producer risk and consumer risk. Moreover, a comparative analysis of the two lifetime testing methods is presented, and the results show that Testing Method II proposed in this study can implement sampling inspection more efficiently. Finally, an example is used to illustrate the proposed methodology.
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(This article belongs to the Special Issue Current Trends in the Mathematics of Fuzzy Sets and Logic)
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Open AccessArticle
Bayesian Inference via Markov Iterative Methods for Generalized Progressive Hybrid Unit Bilal Censoring and Its Applications to Thermodynamics and Meteorology
by
Heba S. Mohammed, Ahmed Elshahhat, Osama E. Abo-Kasem and Asmaa Abdel-Hakim
Axioms 2026, 15(8), 587; https://doi.org/10.3390/axioms15080587 - 4 Aug 2026
Abstract
The increasing availability of bounded lifetime observations in different disciplines has intensified the demand for flexible models capable of accommodating complex failure mechanisms. Motivated by this need, a comprehensive inferential framework is developed for the unit Bilal (UBilal) distribution using generalized progressive hybrid
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The increasing availability of bounded lifetime observations in different disciplines has intensified the demand for flexible models capable of accommodating complex failure mechanisms. Motivated by this need, a comprehensive inferential framework is developed for the unit Bilal (UBilal) distribution using generalized progressive hybrid censoring, which guarantees a minimum number of observed failures while controlling experimental duration. Classical inference is established through maximum likelihood estimation, which is accompanied by asymptotic confidence intervals based on both normal and log-transformed approximations. Moreover, a Bayesian framework using a Metropolis–Hastings Markov chain Monte Carlo algorithm is presented. The proposed methodology further provides inference for important reliability characteristics, including the reliability and hazard rate functions, through both frequentist and Bayesian paradigms proposed. An extensive Monte Carlo investigation is conducted under diverse censoring schemes, sample sizes, and prior specifications to evaluate estimation accuracy, interval performance, and the influence of censoring severity. The simulation results show that Bayesian methods always provide better estimates and more reliable interval estimates, especially when prior information is used. Using two real datasets from thermodynamics and meteorology, the numerical results demonstrate that the UBilal model provides an excellent fit and yields reliable inference under bounded observations. Overall, the proposed methodology presents an efficient Bayesian inferential framework for bounded lifetime data collected through the generalized progressive hybrid censoring and expands the applicability of the UBilal model to reliability and related fields.
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(This article belongs to the Special Issue Applications of Bayesian Methods in Statistical Analysis, Second Edition)
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Open AccessReview
Some Approaches to Solving the KP Equation: Different Representations and Various Types of Solutions
by
Pierre Gaillard
Axioms 2026, 15(8), 586; https://doi.org/10.3390/axioms15080586 - 4 Aug 2026
Abstract
We present different methods to construct solutions to the Kadomtsev–Petviashvili (KP) equation. In the first method, from the solutions to the NLS equation, we construct solutions to the KP equation in terms of Fredholm determinants. We deduce solutions written as quotients of Wronskians
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We present different methods to construct solutions to the Kadomtsev–Petviashvili (KP) equation. In the first method, from the solutions to the NLS equation, we construct solutions to the KP equation in terms of Fredholm determinants. We deduce solutions written as quotients of Wronskians of order . When one of these parameters tends to zero, we obtain N-order rational solutions expressed as a quotient of two polynomials of degree in x, y and t, depending on real parameters. We obtain, in this case, regular solutions to the KP equation. Using new results from the NLS equation, with solutions constructed in terms of quotients of determinants of order N depending on real parameters, we are able to highlight new forms of configurations, such as triangles and concentric rings. Another approach using the Darboux transformation is given to get multi-parametric solutions to the KP equation. In this approach, it is possible to construct an infinite hierarchy of solutions depending on the degree of summation and the degree of derivation. The third method involves choosing special polynomials and using the bilinear Hirota method to get other types of solutions to the KP equation. We also obtain an infinite hierarchy of solutions depending on the order of the determinants. The last method allows the construction of regular solutions to the KP equation. In this approach, we obtain another alternative to obtain regular solutions, as in the case of the first method, and we also observe the formation of configurations such as triangles or concentric rings. We study the configurations of these hierarchies of solutions to the KP equation as a function of their different parameters.
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(This article belongs to the Special Issue Advances in Differential Equations and Its Applications)
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Open AccessArticle
Geometric Frequency Mixing in Helical Waveguides via a One-Dimensional Covariant Helmholtz Model: Gauge Reduction and Spectral Splitting
by
Gülden Altay Suroğlu, Şeyma Firdevs Hızal and Hasan Bulut
Axioms 2026, 15(8), 585; https://doi.org/10.3390/axioms15080585 - 4 Aug 2026
Abstract
This study develops a one-dimensional covariant Helmholtz model for a vector-valued wave field transported along a circular helical centerline and represented in the Frenet–Serret frame. For a helix with constant curvature and torsion , the geometric coupling
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This study develops a one-dimensional covariant Helmholtz model for a vector-valued wave field transported along a circular helical centerline and represented in the Frenet–Serret frame. For a helix with constant curvature and torsion , the geometric coupling is described by a constant skew-symmetric connection matrix . The covariant Helmholtz operator is shown to admit an exact gauge reduction to the flat componentwise Helmholtz operator through . Thus, within the one-dimensional centerline formulation, the helix preserves the operator spectrum while redistributing the observed Frenet components through parallel transport. The closed-form solutions show that a monochromatic input with wavenumber k is decomposed into a carrier and two geometric sidebands governed by the Darboux rotation rate . In the sub-geometric regime , the lower algebraic sideband is represented by the positive observable wavenumber , with associated scale . The lossless energy analysis proves conservation of the total averaged energy and its redistribution among the carrier and observable sidebands. A representative helical acoustic-channel design is then examined as a conceptual realization of the centerline model. Monte Carlo perturbations and additive-noise tests show that the predicted sideband locations, lower-sideband scale, and energy partition remain stable under prescribed fabrication tolerances and spectrally identifiable under weak and moderate measurement noise.
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(This article belongs to the Section Mathematical Physics)
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Open AccessArticle
Saddlepoint Inference for Nonlinear Statistics from Inverse Gaussian Models: Applications to Clinical, Engineering, and Environmental Data
by
Abd El-Raheem M. Abd El-Raheem and Mona Hosny
Axioms 2026, 15(8), 584; https://doi.org/10.3390/axioms15080584 - 3 Aug 2026
Abstract
This paper applies established saddlepoint approximation techniques to nonlinear statistics arising from inverse Gaussian models. In particular, we consider the product of independent inverse Gaussian random variables and the ratio of weighted linear combinations of inverse Gaussian random variables, for which exact distributions
[...] Read more.
This paper applies established saddlepoint approximation techniques to nonlinear statistics arising from inverse Gaussian models. In particular, we consider the product of independent inverse Gaussian random variables and the ratio of weighted linear combinations of inverse Gaussian random variables, for which exact distributions are generally unavailable in closed form. For the product statistic, a logarithmic transformation converts the problem into one involving the cumulant generating function of a sum of log-transformed variables. This cumulant generating function is expressed in terms of fractional moments including modified Bessel functions of the second kind. For the ratio statistic, the event including the ratio is reformulated in terms of a linear statistic, which enables the use of saddlepoint density and Lugannani-Rice distribution approximations. The proposed formulation accommodates heterogeneous model parameters, overlapping numerator and denominator components, and flexible coefficient structures subject to positivity of the denominator. Simulation studies show that the proposed approximations provide accurate results across a range of sample sizes, skewness regimes, and parameter configurations. Furthermore, simulation results indicate that the saddlepoint approximation is more accurate than the normal approximation. Sensitivity analysis confirms that the proposed approximations are reasonably stable under moderate inverse Gaussian parameter misspecification. Three real data applications including clinical illness scores, engineering repair times, and environmental runoff measurements illustrate the practical usefulness of the approach. Overall, the results indicate that the saddlepoint approximation provides an accurate and computationally efficient tool for inference on nonlinear statistics from inverse Gaussian models when exact distributions are not available.
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(This article belongs to the Special Issue Recent Developments in Statistical Research)
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Open AccessArticle
Construction of Multi-Rate QC-LDPC Codes Based on Permutation Method
by
Hengzhou Xu, Jinru Wang, Mei Zhang, Mengmeng Xu and Qian Wang
Axioms 2026, 15(8), 583; https://doi.org/10.3390/axioms15080583 - 3 Aug 2026
Abstract
This paper proposes a systematic permutation-based construction method for multi-rate quasi-cyclic low-density parity-check (QC-LDPC) codes. We first present a graph-theoretic framework in which any regular QC-LDPC code can be normalized to a canonical base matrix that is uniquely determined by a permutation
[...] Read more.
This paper proposes a systematic permutation-based construction method for multi-rate quasi-cyclic low-density parity-check (QC-LDPC) codes. We first present a graph-theoretic framework in which any regular QC-LDPC code can be normalized to a canonical base matrix that is uniquely determined by a permutation . This normalization reduces the complex code design to a single combinatorial optimization problem over the symmetric group. Based on this normalization, we analyze the cycle structure of the lifted Tanner graph and derive necessary and sufficient conditions for 4-cycle elimination in terms of the permutation difference function. We develop two complementary algorithms: a simulated annealing algorithm that searches for permutations that minimize a weighted sum of 4-cycles and 6-cycles, and a progressive column-ordering algorithm that ensures every prefix subgraph maintains high girth. This approach yields a nested family of rate-compatible codes. Simulation results show that the constructed codes outperform the 5G-LDPC codes. The nested base matrix structure facilitates seamless rate switching, which makes the proposed code family well suited for adaptive transmission systems in future wireless networks.
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(This article belongs to the Special Issue Combinatorics and Graph Theory with Applications in Computer Science)
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14 July 2026
Meet Us at the 2027 International Conference on Modern Trends in Mathematical Sciences (ICMTMS 2027), 29 June–2 July 2027, Bucharest, Romania
Meet Us at the 2027 International Conference on Modern Trends in Mathematical Sciences (ICMTMS 2027), 29 June–2 July 2027, Bucharest, Romania
5 August 2026
MDPI INSIGHTS: The CEO’s Letter #37 – Canada Summit, Sciforum Relaunch, 30 Years of Impactful Research & ISPRS 2026
MDPI INSIGHTS: The CEO’s Letter #37 – Canada Summit, Sciforum Relaunch, 30 Years of Impactful Research & ISPRS 2026
Topics
Topic in
AppliedMath, Mathematics, Symmetry, Geometry, Axioms
Functional Equations: Methods and Applications
Topic Editors: Yunyun Yang, Gabriele Bonanno, Sandra PinelasDeadline: 31 August 2026
Topic in
Applied Sciences, Axioms, Information, Mathematics, Symmetry, AppliedMath
Fuzzy Optimization and Decision Making
Topic Editors: Hengjie Zhang, Quanbo Zha, Jing XiaoDeadline: 30 September 2026
Topic in
AppliedMath, Axioms, Fractal Fract, Mathematics, Symmetry
Fixed Point Theory and Measure Theory
Topic Editors: Safeer Hussain Khan, Lateef Olakunle Jolaoso, Olaniyi S. IyiolaDeadline: 30 November 2026
Topic in
AppliedMath, Axioms, Mathematics, Symmetry, Foundations
Function Approximation and Mathematical Modeling
Topic Editors: Luis M. Garcia-Raffi, Vaclav SkalaDeadline: 31 March 2027
Conferences
Special Issues
Special Issue in
Axioms
Differential Geometry and Its Application, 4th Edition
Guest Editor: Mica StankovicDeadline: 20 August 2026
Special Issue in
Axioms
Advances in Fuzzy Logic with Applications
Guest Editors: Diego García-Zamora, Juan Martínez-MorenoDeadline: 30 August 2026
Special Issue in
Axioms
Recent Advances in Fuzzy Sets and Related Topics, 2nd Edition
Guest Editor: Boldizsár Tüű-SzabóDeadline: 30 August 2026
Special Issue in
Axioms
Advances in Mathematical Methods in Optimal Control and Applications, 2nd Edition
Guest Editor: Cristiana J. SilvaDeadline: 30 August 2026



