Linear Integral Operator Research Articles

Mathematical Analysis for Honeybee Dynamics Under the Influence of Seasonality

In this paper, we studied a mathematical model for honeybee population diseases under the influence of seasonal environments on the long-term dynamics of the disease. The model describes the dynamics of two different beehives sharing a common space. We computed the basic reproduction number of the system as the spectral radius of either the next generation matrix for the autonomous system or as the spectral radius of a linear integral operator for the non-autonomous system, and we deduced that if the reproduction number is less than unity, then the disease dies out in the honeybee population. However, if the basic reproduction number is greater than unity, then the disease persists. Finally, we provide several numerical tests that confirm the theoretical findings.

Composition of some positive linear integral operators

Abstract This article is devoted to constructing sequences of integral operators with the same Voronovskaja formula as the generalized Baskakov operators, but having different behavior in other respects. For them, we investigate the eigenstructure, the inverses, and the corresponding Voronovskaja type formulas. A general result of Voronovskaja type for composition of operators is given and applied to the new operators. The asymptotic behavior of differences between the operators is investigated, and as an application, we obtain a formula involving Euler’s gamma function.

Results for Analytic Function Associated with Briot–Bouquet Differential Subordinations and Linear Fractional Integral Operators

In this paper, we present a new class of linear fractional differential operators that are based on classical Gaussian hypergeometric functions. Then, we utilize the new operators and the concept of differential subordination to construct a convex set of analytic functions. Moreover, through an examination of a certain operator, we establish several notable results related to differential subordination. In addition, we derive inclusion relation results by employing Briot–Bouquet differential subordinations. We also introduce a perspective study for developing subordination results using Gaussian hypergeometric functions and provide certain properties for further research in complex dynamical systems.

Nonlocal Changing-Sign Perturbation Tempered Fractional Sub-Diffusion Model with Weak Singularity

In this paper, we study the existence of positive solutions for a changing-sign perturbation tempered fractional model with weak singularity which arises from the sub-diffusion study of anomalous diffusion in Brownian motion. By two-step substitution, we first transform the higher-order sub-diffusion model to a lower-order mixed integro-differential sub-diffusion model, and then introduce a power factor to the non-negative Green function such that the linear integral operator has a positive infimum. This innovative technique is introduced for the first time in the literature and it is critical for controlling the influence of changing-sign perturbation. Finally, an a priori estimate and Schauder’s fixed point theorem are applied to show that the sub-diffusion model has at least one positive solution whether the perturbation is positive, negative or changing-sign, and also the main nonlinear term is allowed to have singularity for some space variables.

Evaluation of integrals for the emptiness formation probability in the square-ice model

We study the emptiness formation probability (EFP) in the six-vertex model with domain wall boundary conditions. We present a conjecture according to which at the ice point, i.e., when all the Boltzmann weights are equal, the known multiple integral representation (MIR) for the EFP can be given as a finite-size matrix determinant of Fredholm type. Our conjecture is based on the explicit evaluation of the MIR for particular values of geometric parameters and on two kinds of identities for the boundary correlation function. The obtained representation can be further written as the Fredholm determinant of some linear integral operator. We show that as the geometric parameters of the EFP are tuned to the vicinity of the arctic curve arising in the scaling limit, the conjectured determinant turns into the GUE Tracy–Widom distribution.

Mathematical Analysis for the Influence of Seasonality on Chikungunya Virus Dynamics

In this article, we discuss a mathematical system modelling Chikungunya virus dynamics in a seasonal environment with general incidence rates. We establish the existence, uniqueness, positivity and boundedness of a periodic orbit. We show that the global dynamics is determined using the basic reproduction number denoted by R0 and calculated using the spectral radius of a linear integral operator. We show the global stability of the disease free periodic solution if R0<1 and we show also the persistence of the disease if R0>1 where the trajectories converge to a periodic orbit. Finally, we display some numerical examples confirming the theoretical findings.

Multilinear rough singular integral operators

AbstractWe study ‐linear homogeneous rough singular integral operators associated with integrable functions on with mean value zero. We prove boundedness for from to when and in the largest possible open set of exponents when and . This set can be described by a convex polyhedron in .

Linear integral operators on Lp\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$L_p$$\\end{document} spaces representing polynomial covariance type commutation relations

In this work, we present methods for constructing representations of polynomial covariance type commutation relations AB=BF(A)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$AB=BF(A)$$\\end{document} by linear integral operators in Banach spaces Lp\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$L_p$$\\end{document}. We derive necessary and sufficient conditions on the kernel functions for the integral operators to satisfy the covariance type commutation relation for general polynomials F, as well as for important cases, when F is arbitrary affine or quadratic polynomial, or arbitrary monomial of any degree. Using the obtained general conditions on the kernels, we construct concrete examples of representations of the covariance type commutation relations by integral operators on Lp\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$L_p$$\\end{document}. Also, we derive useful general reordering formulas for the integral operators representing the covariance type commutation relations, in terms of the kernel functions.

HYBRIDIZATION OF THE LINEAR VISCOELASTIC CONSTITUTIVE EQUATION AND A NONLINEAR MAXWELL-TYPE VISCOELASTOPLASTIC MODEL, AND ANALYSIS OF EVOLUTION SCENARIOS OF THE TRANSVERSE STRAIN COEFFICIENT UNDER CREEP

In this work, a generalization of a physically nonlinear Maxwell-type viscoelastoplastic constitutive equation with four material functions is formulated, whose general properties and range of applicability were discussed in a series of our previous studies. In order to expand the range of rheological effects and materials that can be described by the equation, it is proposed to add a third strain component expressed by a linear integral Boltzmann-Volterra operator with arbitrary functions of shear and volumetric creep. For generality and for the convenience of using the model, as well as for fitting the model to various materials and simulated effects, a weight factor (degree of nonlinearity) is introduced into the constitutive equation, which allows combining the original nonlinear equation and the linear viscoelastic operator in arbitrary proportions and controlling the degree of different effects simulated. Equations are derived for families of creep curves (volumetric, shear, longitudinal and transverse) induced by the proposed constitutive equation with six arbitrary material functions, and an expression is obtained for the transverse strain coefficient as a function of time. Their general properties and dependence on loading parameters and characteristics of all material functions are studied analytically and compared with the properties of similar relations generated by two combined constitutive equations separately. New qualitative effects are identified which can be described by the new constitutive equation in comparison with the original ones, and it is verified that the generalization eliminates some shortcomings of the Maxwell-type viscoelastoplastic constitutive equation, but retains its valuable features. It is confirmed that the proposed constitutive equation is capable of simulating sign alternation, monotonic and nonmonotonic changes in transverse deformation and transverse strain coefficient under constant stress, and their stabilization over time. Generally accurate estimates are obtained for the variation range, monotonicity and nonmonotonicity conditions of Poisson’s ratio, and its negativity criterion over a certain time interval. It is proven that neglecting volumetric creep (the postulate of volumetric elasticity), which simplifies the constitutive equation, greatly limits the range of possible evolution scenarios of the transverse strain coefficient in time: it increases and cannot have extremum and inflection points. The analysis shows that the proposed constitutive equation provides ample opportunities for describing various properties of creep and recovery curves of materials and various evolution scenarios of the transverse strain coefficient during creep. It can significantly expand the range of described rheological effects, the range of applicability of the Maxwell-type viscoelastoplastic equation, and deserves further research and application in modeling.

Influence of seasonality on <i>Zika virus</i> transmission

<abstract><p>In order to study the impact of seasonality on <italic>Zika virus</italic> dynamics, we analyzed a non-autonomous mathematical model for the <italic>Zika virus</italic> (<italic>ZIKV</italic>) transmission where we considered time-dependent parameters. We proved that the system admitted a unique bounded positive solution and a global attractor set. The basic reproduction number, $ \mathcal{R}_0 $, was defined using the next generation matrix method for the case of fixed environment and as the spectral radius of a linear integral operator for the case of seasonal environment. We proved that if $ \mathcal{R}_0 $ was smaller than the unity, then a disease-free periodic solution was globally asymptotically stable, while if $ \mathcal{R}_0 $ was greater than the unity, then the disease persisted. We validated the theoretical findings using several numerical examples.</p></abstract>

Линейные интегральные операторы в пространствах непрерывных и существенно ограниченных вектор-функций

The well-established criterion for the action and boundedness of a linear integral operator K from the space L_∞ of essentially bounded functions to the space C of functions continuous on a compact set is extended to the case of functions taking values in Banach spaces. The study further shows that if the operator K is active and bounded in the space C, it is also active and bounded in the space L_∞, with the norms of K in C and L_∞ being identical. A precise expression for the general value of the norm of the operator K in these spaces, expressed in terms of its operator kernel, is provided. Addicionally, an example of an integral operator (for scalar functions) is given, active and bounded in each of the spaces C and L_∞, but not acting from L_∞ into C. Convenient conditions for checking the boundedness of the operator K in C and L_∞ are discussed. In the case of the Banach space Y of the image function values of K being finite-dimensional, these conditions are both necessary and sufficient. In the case of infinitedimensionality of Y, they are sufficient but not necessary (as proven). For "dim" Y<∞, unimprovable estimates for the norm of the operator K are provided in terms of a 1-absolutely summing constant π_1 (Y), determined by the geometric properties of the norm in Y. Specifically, it is defined as the supremum over finite sets of nonzero elements of Y of the ratio of the sum of the norms of these elements to the supremum (over functionals with unit norm) of the sums of absolute values of the functional on these elements.

Order of Approximation by a New Univariate Kantorovich Type Operator

In order to approximate Lebesgue integrable functions on [0, 1], a sequence of linear positive integral operators of Kantorovich type Lσ<sσ>f (x) with a parameter sσ is introduced. The estimates for rates of approximation for functions with a specific smoothness are proved using the appropriate modulus of continuity.

Global bounded solutions to the Boltzmann equation for a polyatomic gas

In this paper, we consider the Boltzmann equation modeling the motion of a polyatomic gas where the integration collision operator in comparison with the classical one involves an additional internal energy variable [Formula: see text] and a parameter [Formula: see text] standing for the number of internal degrees of freedom. In perturbation framework, we establish the global well-posedness for bounded mild solutions near global equilibria on torus. The proof is based on the [Formula: see text] approach. Precisely, we first study the [Formula: see text] decay property for the linearized equation, then use the iteration technique for the linear integral operator to get the linear weighted [Formula: see text] decay, and in the end obtain [Formula: see text] bounds as well as exponential time decay of solutions for the nonlinear problem with the help of the Duhamel’s principle. Throughout the proof, we present a careful analysis for treating the extra effect of internal energy variable I and the parameter [Formula: see text].

Differential Subordination and Differential Superordination for Classes of Admissible Multivalent Functions Associated with a Linear Operator

In this paper, we first introduce a linear integral operator ℑp(a,c,μ)(μ>0;a,c∈R;c>a>−μp;p∈N+:={1,2,3,…}), which is somewhat related to a rather specialized form of the Riemann–Liouville fractional integral operator and its varied form known as the Erdélyi–Kober fractional integral operator. We then derive some differential subordination and differential superordination results for analytic and multivalent functions in the open unit disk U, which are associated with the above-mentioned linear integral operator ℑp(a,c,μ). The results presented here are obtained by investigating appropriate classes of admissible functions. We also obtain some Sandwich-type results.

On a Novel Algorithmic Determination of Acoustic Low Frequency Coefficients for Arbitrary Impenetrable Scatterers

The calculation of low frequency expansions for acoustic wave scattering has been under thorough investigation for many decades due to their utility in technological applications. In the present work, we revisit the acoustic Low Frequency Scattering theory, and we provide the theoretical framework of a new algorithmic procedure for deriving the scattering coefficients of the total pressure field, produced by a plane wave excitation of an arbitrary, convex impenetrable scatterer. The proposed semi-analytical procedure reduces the demands for computation time and errors significantly since it includes mainly algebraic and linear integral operators. Based on the Atkinson–Wilcox theorem, any order low frequency scattering coefficient can be calculated, in finite steps, through algebraic operators at all steps, except for the last one, where a regular Fredholm integral equation with a continuous and separable integral kernel is needed to be solved. Explicit, ready to use formulae are provided for the first three low frequency scattering coefficients, demonstrating the applicability of the algorithm. The validation of the obtained formulae is demonstrated through recovering of the well-known analytical results for the case of a radially symmetric scatterer.

Delay-Dependent Stability for Load Frequency Control System via Linear Operator Inequality

The stability analysis problem is considered for multiarea load frequency control (LFC) systems with electric vehicles (EVs) and time delays. The novel linear operator inequality approach is proposed and a less conservative delay-dependent stability condition is achieved. First, the model of the multiarea LFC system with EVs and delays is expressed by the partial integral equation (PIE) at the first time. Then, a complete quadratic Lyapunov-Krasovskii functional is built in the form of an inner product of the linear partial integral (PI) operator. The novel stability criteria with less conservatism are proposed in the form of linear operator inequality. Moreover, the relationships between the delay margins and the controller parameters are shown. Finally, the simulations are conducted on both one-area and two-area LFC systems to show the effectiveness of the proposed approach.

Uniform convergence of Nyström discretization on Hölder spaces

We establish that Nyström discretizations of linear Fredholm integral operators on Hölder spaces converge in the operator norm while preserving the consistency order of the quadrature or cubature rule. This allows to employ tools from classical perturbation theory, rather than collective compactness, when studying numerical approximations of integral operators, as well as applications in for instance the field of nonautonomous dynamical systems.

Some Sufficient Conditions for Compactness of Linear Hammerstein Integral Operators and Applications

Some Sufficient Conditions for Compactness of Linear Hammerstein Integral Operators and Applications

Some Weighted Estimates on Gaussian Measure Spaces

In this paper, we obtain the weighted boundedness for the local multi(sub)linear Hardy-Littlewood maximal operators and local multilinear fractional integral operators associated with the local Muckenhoupt weights on Gaussian measure spaces. We deal with these problems by introducing a new pointwise equivalent "radial" definitions of these local operators. Moreover using a similar approach, we also get the weighted boundedness for the local fractional maximal operators with rough kernel and local fractional integral operators with rough kernel on Gaussian measure spaces.

Three-Dimensional Nonlinear Integral Operator with the Modelling of Majorant Function

In this paper, the process for finding an approximate solution of nonlinear three-dimensional (3D) Volterra type integral operator equation (N3D-VIOE) in R3 is introduced. The modelling of the majorant function (MF) with the modified Newton method (MNM) is employed to convert N3D-VIOE to the linear 3D Volterra type integral operator equation (L3D-VIOE). The method of trapezoidal rule (TR) and collocation points are utilized to determine the approximate solution of L3D-VIOE by dealing with the linear form of the algebraic system. The existence of the approximate solution and its uniqueness are proved, and illustrative examples are provided to show the accuracy and efficiency of the model. Mathematical Subject Classification (2010): 45P05, 45G10, 47H99