Iranian Journal of Science and Technology, Transactions A: Science最新文献

In this article, we capture a new Durrmeyer type operator, linking adjoint Bernoulli polynomials with the Baskakov basis functions. We estimate its moments and central moments and provide approximation results which include Korovkin-type estimate in weighted space. Additionally, we present a graphical interpretation of the operators applied to certain functions, quantitative Voronovskaja’s theorem in weighted space, and a theorem involving Peetre’s K-functional. Furthermore, we give theorems based on difference of operators.

The notions of graphical and pointwise limits of a sequence of set-valued functions defined from one metric space into another were studied by Aubin and Frankowska. In this study, by using the concept of (alpha beta)-density of subsets of natural numbers, we introduce the notions of (St^{alpha beta }_{gamma })-graphical and (St^{alpha beta }_{gamma })-pointwise limits of a sequence of set-valued functions defined from one probabilistic normed space into another. Subsequently, the article introduces the notions of (St^{alpha beta }_{gamma })-graph and (St^{alpha beta }_{gamma })-pointwise convergence of these sequences. Moreover, we look at the correspondence between these convergences and establish some associated theorems.

On a compact Riemannian manifold without boundary, this work deals with a non-local Kirchhoff-type double phase problem with variable exponents and without the Ambrosetti-Rabinowitz. The first objective of this work is to establish the existence of least energy solutions by using the Mountain Pass Theorem and the restriction of Nehari manifold. Furthermore, the second objective is to establish the existence of an infinite number of small and large energy solutions. To obtain these multiplicity results, respectively the Fountain Theorem and the Dual Fountain Theorem are used.

In this paper, we propose a new conjugate gradient method where the generated search direction satisfies the sufficient descent condition. Also, the calculation of the new conjugate gradient parameter incorporates the use of the conjugacy condition. Global convergence is established under the strong Wolfe line search and numerical experiments demonstrate the effectiveness and efficiency of the proposed method. Furthermore, the method is used to solve a problem involving motion control of a 2-DOF (degrees of freedom) robotic arm, underscoring its practicality in real-world applications.

Many scientific fields have emphasized studying the dynamic behavior associated with environmental occurrences. Warming of the planet is one such occurrence. The two primary drivers of global warming negatively impacting our ecosystem are temperature and excess greenhouse gases. In light of the importance of this climatic event, we have considered the three climatic variables in this study: temperature, greenhouse gas concentrations, and permafrost thawing in the form of a fractional-order atmospheric model. Using the Hermite wavelet collocation method (HWCM), the system of nonlinear ordinary differential equations of integer and fractional order is numerically solved. The atmospheric model is transformed into an algebraic equation system using the collocation approach and the fractional derivative operational matrices. The Newton–Raphson method of solving these algebraic equations entails inserting the estimated values of the generated unknown coefficients. The present method, ND solver, and RK methods are compared numerically. Furthermore, we demonstrate the method’s effectiveness in various scenarios by running simulations with fractional orders and parameter values. The results confirm the method’s capacity to produce accurate results in many contexts. Tables and graphs show how well the developed strategy performed over time and how effective it was. These results help us analyze the variation of three dependent variables by varying parameter values. The Hermite wavelet collocation method described here is accurate in terms of convergence and computational cost and robust when compared to previous methods in the literature. Mathematica is a mathematical software for numerical computations.

Functional response is vital in understanding and controlling disease dynamics through mathematical modeling. This study introduces the Crowley-Martin (C-M) functional response in tumor-host cell interaction dynamics, which accounts for the handling time of healthy host cells in destroying tumor cells and the magnitude of interference among these cells. When both interference and handling time of healthy host cells in destroying tumor cells are zero, tumor cells are eradicated effectively. As these parameters increase, the system shifts to a state of coexistence. The complex dynamics of the model are explored by discretize the continuous model using Euler’s method. The local stability and bifurcation of the model for different parameter values are studied, and appropriate conditions are established. Numerical simulations validate the theoretical results of Flip and Neimark-Sacker bifurcation, revealing complex dynamical behaviors, including chaotic patterns, which suggest disease progression. Based on the chaos appearing in the bifurcation diagrams, we propose an optimal control strategy to control tumor cell growth by introducing chemotherapy drugs.

Nonlinear differential equations are crucial to models in natural and biological sciences, making them a vibrant and compelling area of research. Fractional differential equations are currently reformed and presented in various formats, establishing their core concepts within a mathematical framework and practical applications. The present work demonstrates the existence and uniqueness of solutions for Hilfer fractional pantograph differential equations with stochastic impulses utilizing fixed point theory. The Banach contraction principle indicates that the solution is unique, and the Lery-Schauder fixed point theorem examines if it exists. Furthermore, the qualitative behavior of the dynamical system has been investigated. Finally, it offers a theoretical implementation.

Radio signal blackout in communication from ground-based stations to fast moving space reentry vehicles and vice-versa is a vital problem in space research missions. Many mitigation solutions, including electrophilic liquid injection into the plasma sheath and creating the magnetic window, have already been proposed and tested successfully in real flights. In this paper after describing the conditions for plasma sheath formation around an entering space vehicle, using scattering matrix method (SMM) and Fresnel coefficients, we showed analytically that up to some injected dust concentration, the radio wave transmission through plasma sheath can be ameliorated and so the blackout period is relatively decreased.

This work investigates the effect of Ce doping in ZnO by sol–gel combustion method on its photocatalytic activity and optoelectronic application. XRD, TEM analysis confirmed the wurtzite hexagonal structure of ZnO. EDX analysis depicted the presence of Ce in addition to Zn and O. UV–Vis studies revealed a decrement in energy band gap on introduction of Ce. PL data analysis showed the existence of various defects which upgrades enhancement of visible emission via activation through diverse wavelengths. The photocatalytic activity of the synthesized nanoparticles was studied by evaluating the degradation of methylene blue (MB) under solar and methyl orange (MO) under xenon light irradiation. Zn_0.99Ce_0.01O showed an efficiency of 96.9% under solar irradiation compared to 41.5% using a light source for the same duration of exposure. Hence sunlight could be considered as the best light source for the elimination of dyes from the water sources in the environment. Moreover, the CIE coordinates of Zn_0.97Ce_0.03O were obtained to be (0.36, 0.38) with CCT of 4574 K at 325 nm which shows warm white light validating its application in household optoelectronic devices.