Sharif Digital Repository

In this paper, the metric theory of Diophantine approximation associated with mixed type small linear forms is investigated. We prove Khintchine–Groshev type theorems for both the real and complex number systems. The motivation for these metrical results comes from their applications in signal processing. One such application is discussed explicitly. © Springer Nature Switzerland AG 2020  

Accurate estimation of formation conditions plays a pivotal role in effectively managing various processes related to hydrates, including flow assurance, deep-water drilling, and hydrate-based technology development. The formation temperature of methane hydrates in the presence of brine greatly affects the efficacy and accuracy of these processes. This work presents a comprehensive and novel comparative analysis of nine distinct machine learning models for accurate prediction of formation temperatures of methane hydrate. This study investigated the application of major machine learning (ML) algorithms including multiple linear regression (MLR), long short-term memory (LSTM), radial basis... 

Interpreting the complex interaction of nanostructured fluid flow with a dipole in a duct, with peripherally uniform temperature distribution, is the main focus of the current work. This paper also sheds light on the changes in the Nusselt number, temperature profiles, and velocity distributions for the fully developed nanofluid flow in a vertical rectangular duct due to a dipole placed near a corner of the duct. A finite volume approach has been incorporated for the numerical study of the problem. It is interesting to note the unusually lower values of the Nusselt number for the higher values of the ratio Gr/Re. Due to the nanostructure in the fluid, an enhancement in the Nusselt number has... 

The current article investigates the influence of radiation as well as gyrotactic microbes in the flow of micropolar nanoliquids through a channel. Flow is assumed to be symmetric across a channel having permeable walls. The work also focuses on the change in mass transport rate and density distribution of motile microbes across flow regimes in a porous channel. The governing nonlinear partial differential equations of the present problem are transformed into ODEs through dimensionless variables. The coupled nonlinear ODEs are numerically addressed by utilizing the quasi-linearization technique. Impacts of the pertinent parameters on the fluid flow are analyzed and demonstrated through... 

Thermal performance of magnetically driven Casson nanofluid over a nonlinear stretching sheet under the influence of entropy, activation energy and convective boundary conditions was analyzed numerically, employing the quasi-linearization method (QLM). The collective behavior of thermophoretic diffusion and Brownian motion along with special effects of viscous dissipation, thermal radiation, heat generation and joule heating are considered in the energy equation for the flow problem. The addition of nanoparticles helps to stabilize the flowing of a nanofluid and maintain the symmetry of the flowing structure. The governing highly nonlinear coupled differential equations of velocity,... 

Type 2 diabetes (T2d), also known as diabetes mellitus or adult-onset diabetes, is a chronic condition that disrupts the body’s insulin regulation, a crucial hormone for controlling blood glucose levels. Glucose, a form of sugar, is the primary energy source for cells in the human bloodstream. Regulating glucose metabolism is vital for the body’s proper functioning. The primary challenges in managing T2d include blood sampling, timely analysis, risk of skin infections, and blood-borne diseases. This paper presents the design of an IoT-based, non-invasive system for monitoring blood glucose levels. Our system utilizes medical sensors to gather data, which is then cleaned and transformed using... 

Context: Given the global significance of wheat production and consumption, it is imperative to achieve high yields of nutritious wheat grains. However, the inadequate availability of zinc (Zn) in salt-affected soils can aggravate salt stress, decrease wheat grain yield, and grain Zn concentration. This study compared the effectiveness of soil Zn application and seed Zn priming in increasing Zn biofortification and grain yield of Zn-biofortified wheat grown in alkaline-calcareous soil affected by salts. Methods: Eighteen pots were filled with alkaline-calcareous soil containing elevated levels of soluble salts and exchangeable sodium (Na). The pots were subjected to soil Zn application (0 or... 

Ternary hybrid nanofluids possess improved thermal characteristics, enhanced stability, better physical strength, and multi-functionality as compared to hybrid or usual nanofluids. The aim of the ongoing study is to explore the novel thermal attributes of hybrid and trihybrid nanofluids through a porous medium. Whereas the nano-composition of cobalt (Co), gold (Au), and zirconium oxide (ZrO2) make amalgamation in the paraffin (Pfin) which is a base fluid. This nano-composition of the proposed nanoparticles, specifically, subject to the base fluid Pfin has not been interpreted before. The analysis not only covers the features of trihybrid nanofluids (Co-Au-ZrO2-Pfin) but it also describes the... 

The COVID-19 (Coronavirus disease 2019) pandemic has become a major global threat to human health and well-being. Thus, the development of computer-aided detection (CAD) systems that are capable of accurately distinguishing COVID-19 from other diseases using chest computed tomography (CT) and X-ray data is of immediate priority. Such automatic systems are usually based on traditional machine learning or deep learning methods. Differently from most of the existing studies, which used either CT scan or X-ray images in COVID-19-case classification, we present a new, simple but efficient deep learning feature fusion model, called UncertaintyFuseNet, which is able to classify accurately large... 

Co2+ and Cr3+-substituted SrBaCu2-xCoxCryFe28-yO46 X-type hexaferrite with x = y = 0, 0.1 to 0.5 (step = 0.1) were prepared through auto-combustion sol–gel method and sintered at 1250 °C for 5 h which was found from thermal analysis. The thermal investigation, phase detection, spectral, magnetic, and dielectric characteristics of the prepared composition were investigated by TGA, XRD, FTIR, VSM, and dielectric measurement. XRD patterns of the entire composition confirmed the development of a single phase of X-type structure. The enhancement in the lattice parameters and cell volume was observed by varying the Co–Cr concentration, attributed to the larger ionic radii substitution. FTIRspectra... 

Hybrid nanofluids are new and most fascinating types of fluids that involve superior thermal characteristics. These fluids exhibit better heat-transfer performance as equated to conventional fluids. Our concern, in this paper, is to numerically interpret the kerosene oil-based hybrid nanofluids comprising dissimilar nanoparticles like silver (Ag) and manganese zinc ferrite (MnZnFe2O4). A numerical algorithm, which is mainly based on finite difference discretization, is developed to find the numerical solution of the problem. A numerical comparison appraises the efficiency of this algorithm. The effects of physical parameters are examined via the graphical representations in either case of... 

This research endeavors to conduct an examination of the thermal characteristics within the duct filled with the copper nanoparticles and water as base fluid. In exhaust systems, like car exhausts, chimneys, and kitchen hoods, duct flows are crucial. These systems safely discharge odors, smoke, and contaminants into the atmosphere after removing them from enclosed places. The study focuses on a laminar flow regime that is both hydrodynamically and thermally developed, with a specified constraints at any cross-sectional plane. To address this, we employ the finite volume method as it stands as a judicious choice, offering a balance between computational efficiency and solution accuracy.... 

Heat transport features of a dusty fluid flow within a resistive porous medium are numerically interpreted under the magnetohydrodynamic environment. Fluid and dust phase characteristics are overlooked against the preeminent parameters. The main concern, in this work, is to analyze how much the resistive porous media affects the dusty flow in the presence of Lorentz force. The use of convection boundary conditions will aid attain the desired heat transfer rate in engineering applications. The nonlinear partial differential equations governing the fluid and dust phase are transmuted into a system of coupled and highly nonlinear ordinary differential equations which are first discretized using... 

Recently, photoelectrochemical conversion (PEC) of water into fuel is attracting great attention of researchers due to its outstanding benefits. Herein, a systematic study on PEC of water using CuFe2O4/ α-Fe2O3 composite thin films is presented. CuFe2O4/ α-Fe2O3 composite thin films were deposited on two different substrates; (1) planner FTO glass and (2) 3-dimensional nanospike (NSP). The films on both substrates were characterized and tested as anode material for photoelectrochemical water splitting reaction. During PEC studies, it was observed that the ratio between two components of composite is crucial and highest PEC activity results were achieved by 1:1 component ratio (CF-1) of... 

Currently, materials with outstanding absorption abilities, such as thin size, better absorbing power, and light weight are the need of industry to resolve the electromagnetic issues. However, the research on optimizing the composition of the material, microstructure and the structure of the absorber are also the important factors for enhancing the absorption features. A metamaterial microwave absorber (MMA) based on nano ferrites with desirable absorption peaks is proposed and simulated. Sol-gel auto combustion route is used to prepare the nanosized Sm doped Co ferrite with Co1+xSmxFe2-2xO4 at x = 0.00, 0.03, 0.06, 0.09, respectively. XRD, VSM, FESEM, and VNA were employed to evaluate the... 

Within the most recent effort, a non-Newtonian inclination magnetized Carreau nanofluid that has such a cubed autocatalysis impact is detailed. When the flow behavior is moved via a magnetic field, the speed of the fluid is thoroughly investigated under these conditions. The findings about the temperature transparency of the Carreau nanofluid are obtained via the use of temperature-dependent heat transfer, and the measurement of the nanofluid’s amount is accomplished by the utilization of homogeneous heterogeneous chemical processes. The physical model is used to construct partial differential equations (PDEs), which are then processed via variables that are comparable in order to obtain... 

We demonstrate for the first time the application of p-NiFe2O4/n-Fe2O3 composite thin films as anode materials for light-assisted electrolysis of water. The p-NiFe2O4/n-Fe2O3 composite thin films were deposited on planar fluorinated tin oxide (FTO)-coated glass as well as on 3D array of nanospike (NSP) substrates. The effect of substrate (planar FTO and 3D-NSP) and percentage change of each component (i.e., NiFe2O4 and Fe2O3) of composite was studied on photoelectrochemical (PEC) water oxidation reaction. This work also includes the performance comparison of p-NiFe2O4/n-Fe2O3 composite (planar and NSP) devices with pure hematite for PEC water oxidation. Overall, the nanostructured... 

Alluring optical and electronic properties have made organometallic halide perovskites attractive candidates for optoelectronics. Among all perovskite materials, inorganic CsPbX3 (X is halide) in black cubic phase has triggered enormous attention recently owing to its comparable photovoltaic performance and high stability as compared to organic and hybrid perovskites. However, cubic phase stabilization at room temperature for CsPbI3 still survives as a challenge. Herein we report all inorganic three-dimensional vertical CsPbI3 perovskite nanowires (NWs) synthesized inside anodic alumina membrane (AAM) by chemical vapor deposition (CVD) method. It was discovered that the as-grown NWs have... 

In this work, we study the role of nanotextured ZnFe2O4/Fe2O3composite thin films fabricated by ultrasonic spray pyrolysis (USP) on the photoelectrochemical water oxidation reactions. The ZnFe2O4/Fe2O3 composites with different molar ratios are deposited on three-dimensional nanospikes (NSP) substrate, and the results are compared with those for planar devices. It is observed that optical absorption and charge separation due to larger surface area is significantly enhanced in nanotextured photoactive ZnFe2O4/Fe2O3 films. After characterization of ZnFe2O4/Fe2O3 composite films with different molar ratios (ZF1, ZF2, and ZF3), we find that the nanotextured ZF1 composite with a molar ratio of... 

The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a...