International Journal of Mathematics and Physics

Numerical analysis of electromagnetic trihybrid nanofluid flow in a convectively heated permeable channel

2023-10-26T06:32:23+00:00

This research aims to examine the tri-hybrid nanofluid flow in a convectively heated permeable channel with the effect of heat generation/absorption. Tri-hybrid nanofluid is formed by suspending three different nanoparticles namely, aluminium oxide (Al2O3), copper (Cu) and nickel (Ni) in the base fluid water (H2O). For stability of the fluid transverse magnetic and electric fields are considered in the fluid model. The aim of this work is to carry out a comparative study for the heat transfer enhancement of base fluid with mono (Al2O3), hybrid (Al2O3+Cu) and ternary (Al2O3+Cu+Ni) nanofluids. This study is implicated in those fields which are dealing with extreme heat or cold conditions, aerospace technology, biosensors, nano-drugs and metal coatings. The boundary layer equations that govern the flow are transformed to dimension-free form by appropriate transformable variables and then solved by using bvp4c program in MATLAB software. It is found that the fluid flow resist by magnetic parameter and assist by electric field, while the thermal profiles rise by enhancing the value of these parameters. Furthermore, numerical outcomes for skin-friction coefficient and Nusselt number are deliberated in graphical form. Thus, it is concluded that, ternary hybrid nanofluid enhances the thermal conductivity of the base fluid more than to traditional or hybrid nanofluid.

Solution of one boundary value task of viscoelasticity in a nonlinear formulation, in the case of a cubic stress-strain relation

2023-11-27T08:40:27+00:00

In this paper, the solution of a boundary value task in the nonlinear formulation is considered by the authors [1][2]. In spite of its proximity to linear theory, the nonlinear theory of viscoelasticity has not yet been fully developed. This issue is far from being fully completed, since the existing calculation methods do not yet provide a complete answer to the many different questions posed by practice. For this reason, in order to obtain a nonlinear law relating the strains σ_ij and deformations ε_ij a number of conditions are formed:

The specific work of deformation A must be a function of the entire deformation history from the beginning of deformation to the current time
The material of a viscoelastic body is homogeneous and
For very small deformations the nonlinear relation law between σ_ij and ε_ij in the limit should pass to relations in linear

The Numerical Study Distribution of the Temperature Field in a Constructing Element of a Complex Form

2023-11-27T08:17:46+00:00

Many parts of internal combustion engines, gas turbine power plants, steam generators of nuclear power plants and manufacturing industries experience thermal effects of various forms. At the same time, a process of thermal expansion occurs on these parts and, as a result, a thermal stress-strain state arises on them with a value that in some cases can exceed the limit value. Therefore, knowledge of the stationary field of temperature distribution in the volume of partially thermally insulated parts of a complex configuration in the presence of a heat flux and heat exchange in parts of its surface is an urgent task. At the same time, it is very difficult to take into account all inhomogeneous boundary conditions when solving the problem of stationary heat conduction. Therefore, a new numerical method is proposed, based on the law of conservation of total thermal energy in combination with the finite element method. In this case, the procedure for minimizing the total thermal energy is used using quadrilateral bilinear finite elements. Partial thermal insulation, heat flux supplied to the local surface, and the process of heat exchange through the local surface area and ambient temperature are taken into account. Nodal temperature values are determined.

On a non-local problem for system of partial differential equations of hyperbolic type in a specific domain

2023-11-29T04:39:08+00:00

The non-local problem for second order system of partial differential equations of hyperbolic type is studied in the specific domain. For solving this problem we use a functional parametrization method. This method is an extension of Dzhumabaev’s parametrization method to a partial differential equations of hyperbolic type. We introduce a parameter-function, expressed as the unknown function's value at the characteristics within the given domain. This transforms the nonlocal problem into an equivalent parameterized problem, involving the Goursat problem for a system of partial differential equations of hyperbolic type and an additional relation based on the functional parameter. Subsequently, starting from the additional condition and the consistency condition, we formulate the Cauchy problem for a system of differential equations with respect to the unknown parameter-function. We develop an algorithm for solving the parameterized problem and demonstrate its convergence. Additionally, we derive conditions for the existence and uniqueness of a solution to the parameterized problem. Unique solvability conditions for the nonlocal problem for second-order system of partial differential equations of hyperbolic type in a specific domain are established in terms of the initial data.

An Analytical Approach for Solving Fractional Financial Risk System

2023-12-11T04:49:00+00:00

This article introduces an innovative analytical method tailored to address the complexities of non-linear FFR ("fractional financial risk") models. The LRPS ("Laplace residual power series") approach non-linear FFR models empowers risk analysts to more accurately assess portfolios and predict potential losses spanning diverse risk categories. These encompass credit risk, market risk, model risk, liquidity risk, and operational risk. By expanding the array of techniques for risk modeling, this study offers a valuable asset for refining risk assessment and management strategies across these distinct risk domains. Through the utilization of the LRPS approach, this methodology rapidly generates accurate solutions, providing an efficient pathway for approximating the intricate non-linear FFR models intrinsic to risk modeling. By means of numerical simulations and graphical representations, the article effectively demonstrates the efficacy of the LRPS technique. This study not only offers a practical and time-efficient tool for financial risk analysis but also contributes valuable insights to the advancement of novel techniques within the realm of financial risk management.

Effect of nitrogen concentration on titanium nitride thin film formation

2023-11-20T04:16:29+00:00

This paper presents the study of the influence of argon/nitrogen gas concentration ratio in the of reactive magnetron sputtering process on the formation of titanium nitride (TiN) thin films. The addition of 5% nitrogen to the gas mixture is sufficient for the formation of titanium nitride films. It was found that changing the concentration of nitrogen in the reactive gas mixture affects the morphology of the surface, in particular, increasing the concentration of nitrogen leads to an increase in surface roughness of the resulting TiN films. According to the results of Raman spectroscopy, there is a dependence of the ratio of peak areas (TO + LO)/(TA + LA) observed in the regions of 603, 175 and 315 cm^-1, respectively, on the N₂ concentration. The X-ray Photoelectron Spectroscopy (XPS) analysis results show that increasing the nitrogen content in the reactive gas leads to a decrease in the oxygen concentration in the thin films. The results deepen the understanding of the synthesis of TiN thin films and their potential for the development and improvement of materials for various applications including microelectronics, optics, and coatings.

The investigation of radiation effect on tungsten and molybdenum materials

2023-11-01T09:35:15+00:00

This work studied damage and erosion of the tungsten and molybdenum after exposure to deuterium ions of a Plasma focus device. The main purpose and idea of this research work was an experimental investigation of surface changes on the tungsten and molybdenum materials at deuterium optimal gas pressure in the chamber of a PF device. Before and after irradiation the sample surfaces were analyzed using SEM, AFM and an optical microscope. The analysis showed that the change in surface relieves, different types of damage on materials dependent on irradiation parameters. With increasing the number of shots the micro-cracks, and radiation swelling for molybdenum, also the crater, bubbles, holes and cavities on the tungsten sample surface were observed respectively. It is established that a noticeable erosion of tungsten and molybdenum samples as a result of irradiation with plasma flows simulating a stationary regime occurs only at relatively high sample surface temperatures.

Accurate High-Altitude Orbit Determination Method using Electro-Optical Sensors

2023-12-11T03:31:04+00:00

This manuscript presents an approach to accurately determine the orbits of Medium Earth Orbit (MEO) and Geosynchronous Earth Orbit (GEO) space objects by utilizing data from an electro-optical sensor (Optical Satellite Tracking Station (OSTS), Kottamia Observatory station). The proposed method combines an extended and unscented Kalman filter with a semi-analytical propagation model. The effectiveness of this approach is demonstrated through numerical simulations and comparisons with traditional orbit determination techniques. The results drawn from this study show that when comparing both methods, the unscented semi-analytical Kalman filter provided more accurate orbital state estimates and required less time and fewer observations to converge.

Time evolution of an anisotropic universe under Kaluza-Klein framework with a dynamical cosmological constant

2023-11-30T07:12:57+00:00

The objective of the present study is to determine the time evolution of the universe with zero spatial curvature, under Kaluza-Klein framework, in the presence of an anisotropic fluid. To derive the field equations, we have used a power law relation between the normal scale factor and the extra-dimension scale factor. Time-variation of cosmological quantities depends upon the parameter that connects these scale factors. Using an ansatz for a hybrid scale factor (i.e., a = t^αe^βt) we have derived expressions for various cosmological parameters in terms of cosmic time and depicted their time dependence graphically. The dynamical cosmological term (Λ) varies extremely slowly at the present time, indicating a slow change in the dark energy content of the universe which is held responsible for cosmic acceleration. The pressure associated with the fifth dimension has been expressed in terms of a skewness parameter (δ). Its behaviour shows that the present universe has a small anisotropy and it becomes smaller with time. This observation is consistent with the behaviour of the anisotropy factor which decreases with time.

Simulation photoconverters of porous-Si/Si with different anti-reflective coatings

2023-12-20T07:13:11+00:00

Целью данной работы является исследование перспективных фоточувствительных структур солнечной энергетики на основе гетероструктуры пористый Si/Si с просветляющими покрытиями и без них. Для моделирования фотоконвертированных параметров использовалась программа PC1D. Изучены спектры отражения кремниевых солнечных элементов без покрытия и с просветляющими покрытиями SiO ₂ , TiO _{2 , ZnO, ZnS.}Установлено, что коэффициент отражения чистой гетероструктуры пористый Si/Si на длине волны около 500 нм достигает 37 %, тогда как коэффициент отражения от АРО составляет не более 13 % для той же длины волны в случае падения света на 30°, а при угле падения солнечного света 45° значение коэффициента отражения составляет ⁓31% для пористого Si/Si и не превышает 16% для солнечных элементов с просветляющими покрытиями на длине волны около 500 нм. На основе исследованных структур были рассчитаны характеристики фотопреобразователя света, а также построены вольт-амперные характеристики. Первоначальные результаты моделирования показывают, что эффективность солнечных элементов на основе пористого Si/Si составляет около 17,5%. Значительного повышения эффективности солнечных батарей удалось достичь благодаря использованию антибликового покрытия. Среди четырех материалов просветляющее покрытие TiO ₂ имеет наибольшее значение эффективности, которое достигло 26,4%. Изучено влияние текстурирования фронтальной поверхности на эффективность солнечного элемента. В отсутствие текстурирования эффективность солнечного элемента пористого Si/Si составила 17,1%, а с текстурированием достигла значения 18,1%. Для конструкций с просветляющим покрытием эффективность составляет 17,3% (SiO2 ₎ , 25,4% (TiO2 ₎ , 19,8% (ZnO), 19,8% (ZnS) без текстурирования поверхности и 18,3% (SiO2 ₎ , 26,4% ( TiO ₂ ), 20,7 % (ZnO), 20,9 % (ZnS) с текстурированием. Рассмотрено влияние рабочей температуры на электрические характеристики солнечного элемента. Установлено, что повышение температуры приводит к снижению эффективности исследованных структур на: 2,5 % (без просветляющих покрытий), 2,3 % (SiO 2 ), 1,8 % (TiO 2 ), 2,4 % ₍ ZnO ₎ . , 2,9% (ZnS).

Tailoring of ZnO thin films: effect of number of coating and sample ageing

2023-12-23T06:59:55+00:00

In this work, the effect of number of coating and sample ageing on the properties of ZnO thin films prepared by dip coating technique using 0.1 M aqueous solution of zinc acetate and methanol on the glass substrate was experimentally investigated. The linear four probe configuration has been used to measure sheet resistance of the deposited samples whereas laboratory purpose Hall-effect measurement apparatus has been used to measure carrier concentration and Hall mobility. The dark sheet resistance (180.37 kΩ/□ to 41.69 kΩ/□) and normal sheet resistance (163.15 kΩ/□ to 31.72 kΩ/□) of ZnO thin films decreases significantly as the sample age increased from 79 to 167 days, particularly for films deposited with 8, 12, 16, and 20 coats. It is also found that as the number of coating increases, thickness of the thin films (from 199.7 nm to 211.5 nm) and carrier concentration increases whereas the Hall mobility decrease. The spectrophotometer (USB2000, photonics) has been used to investigate optical properties of deposited films. All the ZnO thin films demonstrate remarkable transparency, exhibiting transmittance lies between 61% and 85% across the wavelength range of 450 nm to 950 nm. The optical transmittance is observed to decrease with increase in number of coating in the wavelength range 650 to 950 nm. The optical band gap value increases slightly from 3.22 eV to 3.25 eV for corresponding number of coating from 8 to 20. This slight change in optical band gap indicates that it does not depend significantly on number of coating and thickness of the films.