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

In this paper, we describe a new modified orthogonal Saban frame for timelike and spacelike curves with geodesic curvature on (S^{2}_{1}) and the Saban frame for hyperbolic curves with geodesic curvature on (H^{2}_{0}). We study the evolution of curves depending on the modified orthogonal Sabban frame and we obtain the necessary conditions for the inextensible flow of curves on modified orthogonal Saban frame.

The paper presents a novel technique for solving the fractional telegraph equation (FTE) using a combination of the Chebyshev collocation method and finite difference scheme. FTE is a generalization of the classical telegraph equation and is widely used in many areas of physics and engineering. The proposed method combines the advantages of both Chebyshev collocation and finite difference schemes to provide accurate and efficient solutions. A detailed error analysis is carried out to investigate the convergence behavior of the scheme and is compared with other numerical methods. Examples are given to demonstrate the efficiency and accuracy of the method and highlight its potential for solving more complex problems. Overall, our results show that the combined method of Chebyshev collocation and finite difference is a potent tool for solving FTE, providing reliable and accurate solutions with excellent convergence rates.

This paper focuses on the development and analysis of predictor-corrector methods for solving stochastic advection–diffusion equations. These equations play a significant role in modeling various physical phenomena where uncertainties are present. We first derive the predictor-corrector schemes and analyze their stability, consistency, and convergence in the mean-square sense. The results indicate that under appropriate conditions, the proposed methods maintain stability and exhibit desirable convergence properties. Additionally, we present a detailed comparison of the stability of these methods with some other existing numerical approaches. Numerical experiments validate the theoretical findings and demonstrate the accuracy and robustness of the methods. Although this study is primarily concerned with linear stochastic partial differential equations, we also discuss the potential extension of these methods to nonlinear cases, providing a foundation for future research in this direction.

In this work, an efficient computational technique based on Lucas polynomials has been extended to approximately solve a certain class of fractional diffusion equations. Fractional order Lucas polynomials were used to represent the operational matrix of differentiation and integration. Subsequently, the fractional Klein–Gordon equation was reduced to a system of algebraic equations whose solution can be found through suitable algorithms such as Gauss elimination and Newton–Raphson methods. Based on the numerical results obtained, the proposed technique demonstrates a high level of efficiency and precision.

Coating gas pipelines is a crucial practice in the gas industry to enhance pipeline integrity, longevity, and safety. Recently, the outer wrap tape of bitumen impregnated glass fiber have been developed as the part of protective layers for the underground pipelines. Outer tapes prepared of pre-modified 10/20-grade bitumen by styrene–ethylene/butylene–styrene (SEBS), styrene–butadiene–styrene (SBS), and talk powder suffer from some problems such as brittleness at low temperatures, inadequate adhesion between the two glass fiber layers, and high weight. Therefore, the aim of this study was to survey the physical, rheological, and adhesion characteristics of pre-modified bitumen after addition of polyethylene glycol (PEG) 2000 and then to investigate the quality of the tape produced with this bitumen. Improvement of flexibility and decrease of susceptibility to deformation at low temperatures of PEG-modified samples were confirmed by penetration, softening point, and penetration index (PI) tests. The storage stability investigation showed that at higher PEG concentrations phase separation may happen. Dynamic shear rheological (DSR) test indicated that PEG-modified samples have lower complex modulus and complex viscosity. Tapes produced with PEG-modified bitumen displayed less brittleness and enhanced adhesion than those produced with unmodified bitumen. Generally, this study highlights the potential of PEG as a promising additive to prepare bitumen with desired properties. These findings contribute to the development of gas pipe coating technology in cold regions, specifically the production of outer wrap tapes.

Graphical Abstract

Though Zemu is the largest glacier in the Eastern Himalayas, it is one of the least monitored among the Himalayan glaciers. Thus, its sensitivity to global climate change should not be neglected. Glacier boundary delineation is a labor-intensive and time-consuming process. Therefore, the primary objective of this study is to create a semi-automatic processing chain that can recognize glacier boundaries using Synthetic Aperture Radar (SAR) data, Principal Component Analysis (PCA), and Connected components segmentation (CCS) techniques. SAR data processing provides weather-independent, high-resolution data that captures the surface characteristics of the glacier, including backscatter intensity and coherence, which are crucial for detecting glacier boundaries. PCA reduces data redundancy and enhances the spatial characteristics of the input data. CCS groups pixels with similar intensities into segments. Combining these methods results in a more accurate and reliable delineation of glacier boundaries. The parameters we have selected for the process are unique. Earlier researchers have used coherence and slope information. However, we have also considered the effect of radar backscattering intensity and curvature of the study area in addition to coherence and slope information. The use of CCS gives uniqueness to this study. A qualitative analysis of the study showed similarity with the GLIMS glacier outline, and the Intersection over Union (IoU) metric for segmentation accuracy was 0.67. Additionally, the two-pass Differential SAR Interferometry (DInSAR) technique was used for estimating the LOS velocity of the Zemu glacier. The significance is that LOS velocity measurements help track the movement of glaciers over time.

The main intent of this paper is to examine some approximation properties of Riemann-Liouville type fractional Bernstein-Stancu-Kantorovich operators with order of (alpha). We derive some moment estimates and show the uniform convergence theorem, degree of convergence with respect to the usual modulus of continuity, class of Lipschitz-type continuous functions and as well as Peetre’s K-functional. Furthermore, we present various graphical and numerical examples to demonstrate and compare the effectiveness of the proposed operators. Also, we construct bivariate extension of the related operators and consider order of approximation by means of partial and complete modulus of continuity. Further, we provide a graphical representation and an error of approximation table to show the behavior order of convergence of bivariate form of discussed operators.

Removing pesticides from water is essential to protect ecosystems and preserve water sources from pollutants. The use of nanocomposites for adsorption removal has gained attention in the last decade. In this work, Mg-Al double-layer hydroxide coated on graphene oxide (Mg-Al-LDH@GO) was synthesized and characterized using FESEM, EDS, and XRD techniques. The removal of dimethoate from aqueous solution using Mg-Al-LDH@GO as an adsorbent was optimized and modeled. The response surface method (RSM) was employed to design the experiments based on the central composite design (CCD). Four parameters affecting the adsorption removal efficiency of dimethoate, including pH, contact time, adsorbent dose, and pollutant concentration, were optimized using RSM-CCD. The results indicate that the removal process can be accurately predicted by the quadratic model. Numerical optimization results showed that when the concentration of dimethoate is 83.7 mg/L, the optimal conditions are pH 2.6, contact time 15.3 h, and adsorbent dose 27.5 mg/100 mL. Under these conditions, the removal efficiency reached 86.08%. A feed-forward neural network (ANN) model with the Levenberg-Marquardt backpropagation training algorithm was adapted to model the removal process. The performance of the ANN model showed adequate response prediction with R² values of 0.9989, 0.9803, 0.9984, and 0.9936 for training, validation, testing, and overall, respectively. The results obtained in this work demonstrate that Mg-Al-LDH@GO is a potential adsorbent for the removal of dimethoate from water.

Although the origin of cosmic rays and spectral breaks remains a controversial issues, it is evident that the energy spectrum of cosmic rays does not follow a Gaussian distribution and therefore, cannot be described using ordinary statistical mechanics. In this study, we apply Beck-Cohen superstatistics, a generalized framework of statistical mechanics. In this model, the main idea is that the energy spectrum of cosmic rays results from many high-energy scattering processes, each with a different local temperature (beta) in the local scattering volume. By considering the temperature fluctuations, one can not only obtain Tsallis statistics but also an infinite set of statistics. In this paper, we utilize a gamma distribution to describe these temperature fluctuations, employing shape and scale parameters as essential tools. Our approach facilitates the derivation of a novel relationship for the entropy index q as a function of energy, which has not been previously explored in the context of cosmic rays. The effective temperature is estimated to be 100 MeV, aligning with the generalized Hagedorn temperature. Importantly, our theoretical results show strong agreement with available experimental data.

This study focuses on the synthesis, characterization, and application of a microporous nanomaterial made from a metal-organic framework called ZIF-8. The material was successfully prepared and used to investigate its ability to load and release dapsone in water-based solutions. This prepared ZIF-8 exhibited promising drug loading from aqueous environments through hydrogen bonding, π-π, and electrostatic interactions. The synthesized ZIF-8 was characterized through Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, Elemental mapping analysis, thermogravimetric analysis, and Brunauer–Emmett–Teller analysis to investigate its structure and morphology. The study investigated several factors that could influence the dapsone loading procedure, including pH, ZIF-8 dosage, and loading time, to optimize the process. Using the non-linear simplex optimization methodology, it was found that the efficiency of loading dapsone exceeded 92.5 ± 3.9% when the concentration of the dapsone drug was 50 mg.L^-1. The most effective parameters for achieving the highest possible loading of dapsone were loading pH = 7.0, ZIF-8 dosage = 6.0 mg.mL^-1, and loading time = 120 min. Investigative studies on release mechanisms demonstrated that when the dapsone-loaded ZIF-8 was submerged in phosphate buffer saline (at pH = 7.4 and temperature = 37 °C), it displayed an optimal efficiency surpassing 80% following a duration of 120 h.