Article of the Year 2021
The Principle of Intelligent Switch Composition and Algorithm of the Built-In Electronic Voltage TransformerRead the full article
Journal of Applied Mathematics publishes original research papers and review articles in all areas of applied, computational, and industrial mathematics.
Chief Editor, Professor Theodore E. Simos, is based at Ulyanovsk State Technical University, Russia. His main research interest is the numerical analysis of differential equations.
Latest ArticlesMore articles
Numerical Analysis of Forced Convection of Nanofluid under Turbulent Flow between Two Parallel Plates
As research shows, in new and renewable energy systems, including solar energy, the study of turbulent flow is of great importance due to its high efficiency in heat transfer. It is also used in petrochemical and oil industries and cooling systems. Therefore, this paper focuses on the turbulent heat transfer of nanofluid between two parallel plates and the effect of the volume fraction of nanoparticles on turbulent heat transfer is investigated. The nanofluid applied in the study was alumina-water. The beginning and the end of the walls were insulated, and the middle part was considered as the heat source. The two-equation - model was used to model viscosity of turbulent flow. The governing equations were solved simultaneously using the control volume method based on SIMPLER algorithm. In this study, the effects of the Reynolds’ number in the range of 104 to , volume fraction of 0.01 to 0.04, and nanoparticle diameter of 20 nm to 100 nm on field flow and rate of heat transfer were examined. The influence of Brownian movement on heat performance was considered. Evaluation showed that increasing the Reynolds’ number decreased the thickness of the laminar sublayer in turbulent flow and increased temperature and velocity differences. These greater temperature and velocity differences resulted in increased heat transfer and decreased skin friction. The findings imply that heat performance improves when nanoparticles are added to basic fluid. With increasing volume fraction of nanoparticles, shear stress of the channel wall increases, and consequently, skin friction increases too. In addition, the effect of nanoparticle diameter on thermal and hydraulic performance was studied. It was found that heat transfer and skin fraction decreased in the presence of the larger nanoparticles.
Modeling and Analysis of Predator-Prey Model with Fear Effect in Prey and Hunting Cooperation among Predators and Harvesting
In this paper, we present and analyze predator-prey system where prey population is linearly harvested and affected by fear and the prey population has grown logistically in the absence of predators. The predator population follows hunting cooperation, and it predates the prey population in the Holling type II functional responses. Based on those assumptions, a two-dimensional mathematical model is derived. The positivity, boundedness, and extinction of both prey and predator populations of the solution of the system are discussed. The existence, stability (local and global), and the Hopf bifurcation analysis of the biologically feasible equilibrium points are investigated. The aim of this research is to explore the effect of fear on the prey population and hunting cooperation on the predator population, and both prey and predator populations are harvested linearly and taken as control parameters of the model. If the values of , then both prey and predator populations are extinct and also fear parameter has a stabilizing effect on system 4. From the numerical simulation, it was found that the fear effect, hunting cooperation, prey harvesting, and predator harvesting change the dynamics of system 4.
Comparison of the Flow Fields between Nozzles with Full-Open and Open-Close Valves at Transonic Velocity
At transonic velocity, ejector nozzles require third auxiliary intake valves to increase air intake, resulting in good thrust performance. However, different intake structures will inevitably lead to different internal flow-field structures and thrust performances. To evaluate the differences between nozzles with full-open valve and open-close valve at transonic velocity, we established two numerical simulation models to analyze the flow-field structure and thrust performance in the ejector nozzle. The results show that at the transonic flight state (), the mainstream of the two models always maintains an overexpansion state, and the primary flow fields are highly similar. However, the secondary and the third auxiliary flow fields are significantly different. Notably, in the nozzle with open-close valve, a lateral flow occurs near the wall of the nozzle tail, resulting in several vortexes. Contrarily, in the nozzle with full-open valve, there is almost no lateral flow or vortex. Further, we found that the secondary flow tends to roll up toward the third auxiliary valve instead of directly flowing into the nozzle. Thus, the thrust coefficients of the two nozzles differ.
Aquaculture Prediction Model Based on Improved Water Quality Parameter Data Prediction Algorithm under the Background of Big Data
Computer science and technology under the background of big data are closely related to the development of modern agriculture. The application of information processing technology in aquaculture will promote the scientific development of aquaculture. The aquaculture water quality directly affects the effect of aquaculture. Therefore, on the basis of the dynamic monitoring model of water quality, the relevant factors affecting water quality were analyzed, and a prediction model of aquaculture water quality was constructed. Considering the complex relationship between dissolved oxygen and water quality, combined with principal component analysis, a PCA-BP (principal component analysis back propagation) water quality prediction model was proposed. The parameters of PCA-BP water quality prediction model were optimized by genetic algorithm, the threshold and weight of BP neural network were determined, and an improved PCA-BP water quality prediction model was constructed. The experimental results show that the relative error of the GPCA-BP water quality prediction model for the prediction of dissolved oxygen content is less than 0.76% in water quality prediction experiments in different times and regions, and it has the best prediction accuracy. At the same time, GPCA-BP water quality prediction model also has excellent performance in convergence accuracy, prediction accuracy, and MAE error performance test. The research content has important reference value for the application of information technology in modern aquaculture.
Application of Big Data Clustering Algorithm in Electrical Engineering Automation
The existing control methods have the problem of imperfect automatic distribution linkage model, which leads to excessive noise in the process of practical application. This paper designs an electrical engineering automation control method based on big data clustering algorithm, obtains the load parameters of power cable laying mode, arranges the cable channels hierarchically, extracts the technical characteristics of electrical engineering automation control, integrates the equipment operation information, builds the automatic distribution linkage model, mines the data rules of power index, sets the distribution structure of electrical equipment by big data clustering algorithm, and centrally configures the functional units.Experimental Results. Compared with the other two control methods, the average noise of this control method is 19.774 dB, 35.462 dB, and 36.323 dB, which proves that the control method combined with big data clustering algorithm has better practical application effect.
A Fundamental Criteria to Establish General Formulas of Integrals
In this study, new master theorems and general formulas of integrals are presented and implemented to solve some complicated applications in different fields of science. The proposed theorems are considered to be generators of new problems, including difficult integrals with their exact solutions. The results of these problems can be obtained directly without the need for difficult calculations. New criteria for treating improper integrals are presented and illustrated in four interesting examples and some tables to simplify the procedure of using the proposed theorems. The outcomes of this study are compared with those presented by Gradshteyn and Ryzhik in the classical table of integrations. The results in this study are simple and applicable in solving integrals, and some of the well-known theorems in calculating improper integrals are considered simple cases of our research.