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In this paper, the issue of heat transfer in three-dimensional solid objects, a special form with cylindrical geometry, is investigated using the numerical finite element method by the commercial software Abaqus. Heating and cooling in food processing are common activities, heating food for a variety of purposes such as reducing microbial aggregation, inactivating enzymes, reducing the amount of nutrient water, modifying the functional properties of a particular compound, and cooking when heat transfer is performed. It plays a central role in all these operations. In this paper, a cylindrical geometry specimen with a temperature of 200 °C is used to investigate the temperature variations of potatoes in high-temperature oil. The results of numerical modeling of potato slices in high-temperature oil show that the rate of changes in the edges of the model is higher than in other parts of the model, which is a factor for the burns of potato edges. Also, the temperature variations in the center of the model have the lowest changes in the logarithmic distribution of heat transfer in the cylinder radius. In addition, with the increase in an exposure time of potato samples in high-temperature oil, almost all models reach the same temperature conditions. [ABSTRACT FROM AUTHOR]

Electric field intensity is one of the factors affecting the corona discharge and insulation of high voltage composite insulators. Accordingly, it is necessary to adjust the potential distribution and electric field along the insulator. Using the corona ring on the high voltage side has a great potential to minimize the intensity of the electric field. Since the design and installation conditions of the corona ring can change the electric field, in this paper, Derivative-Free Solvers (DFS) based numerical solution methods are used to obtain optimal parameters. Three-dimensional finite element method (FEM) in COMSOL software is employed to simulate and compute the electric field. Comparison of the results has shown that Derivative-Free Solvers have acceptable speed and good convergence. The parameters obtained from the optimization methods can reduce the electric field by up to %66. According to the results, FEM-DFS hybridization technique could be very helpful in optimization of corona ring design. [ABSTRACT FROM AUTHOR]

Permanent magnet machines are widely used in wind turbines due to theirs prominent characteristics. The direct-drive wind generators have large size and high manufacturing cost because of low operational speed so that these disadvantages deteriorate when the rated output power increases. Therefore, the main objective of the optimal design proposed in this paper is to minimize the wind turbine system cost maintaining the high efficiency characteristic. Thus, a multiphysics model of the wind generation system is firstly presented to be the basis of the optimal design. One of the paramount feature of the current study is to precisely calculate all of the energy production costs, including the manufacturing cost of generator, power converter, electrical subsystem, and also wind turbine tower cost. In order to obtain the optimum solution, the Genetic Algorithm (GA) optimization method is implemented with consideration of a predetermined proper range for optimal variables. By comparing the optimal design results with those attained by the innerrotor permanent magnet generator, the superiority of the proposed method is justified in terms of the total volume, weight, and annual output energy. Eventually, the finite element analysis has also been carried out to validate the outcomes obtained from the proposed optimal design. [ABSTRACT FROM AUTHOR]

Eccentricity fault is one of the prevalent faults in rotating machines which can cause other mechanical and electrical faults. This paper focuses on detecting the static and dynamic eccentricity faults in the squirrel-cage induction motors. The induction motor is modeled by the finite element method (FEM), a powerful and accurate method, using FLUX 2D software. The current signal cannot be used to detect the static and dynamic eccentricity faults especially when their severity is small. Therefore, the search-coil based method is employed and the voltage of two symmetrical search-coils is analyzed to detect and diagnose the static and dynamic faults. Since two search-coils are open-circuit, they do not affect the behavior of the induction motor. The analysis based on the principal component analysis (PCA) method shows that there exists an intelligent pattern that, firstly, is sensitive to the occurrence of eccentricity faults, even to a low degree, and secondly, has the ability to distinguish the type of fault (static or dynamic). [ABSTRACT FROM AUTHOR]