Teodor Leuca

Temperature variation in the process of heating oak wood using radio frequency

The main purpose of the study presented in the paper is to follow the evolution in time of the temperature computed in the dielectric material in the process of heating oak wood using radio frequency. Depending on different values of time and anode voltage the evolution in time of the temperature computed in the absorbent charge is being studied using Comsol Multiphysics software.

The influence of the high frequency electromagnetic field on grape processing

In this paper we present both results obtained by numerical modeling and experimental results of grape processing in high frequency electromagnetic field. Numerical modeling was performed with the HFSS 15.0 software for the processing in high frequency field. Experimental determinations were made with an applicator with adjustable power from 100 to 1000 W. The following varieties of grapes were processed: Muscat Ottonel, Merlot, and Pinot Noir (harvested in the Crişana-Santimreu vineyard in 2014). The three chosen varieties are characterized by different color and aroma. In our research we aimed at establishing effective processing techniques both in terms of energy and to obtain a high quality final product.

Statistical optimization of dielectric material's placement inside a microwave applicator using response surface method

The position of a dielectric material inside the applicator of a microwave installation is analyzed and optimized using the Box Behnken type of experiment; this type of experiment can be found inside the optimization software known as “Minitab”. An experiment having three factors and three levels was carried out. ANOVA - Analysis of Variance was used to study the influence that the factors have on responses. The objective of optimization was to process corn seeds in microwave field for obtaining a humidity that is well-suited for good storage; another objective was to meet the quality requirements for the treated material. The numerical modeling software called Comsol Multiphysics was used for studying the influence that the factors have on the optimization response.

Thermal treatment of ferromagnetic pieces at medium frequency

The paper is a continuation of the research reported by the authors regarding the eddy-current heating analysis of a ferromagnetic piece heating equipment. The previous results were dedicated to circular conductors, whereas, in the present paper bars of any the cross-section shape are considered. The electromagnetic field depth of penetration being sufficiently small in comparison with the other geometrical dimensions of the bar, we will take into account only a zone in the vicinity of the bar surface, having a thickness of five times the depth of penetration. Along this depth, the problem is one-dimensional and a combined numerical and analytical approach will result in an extremely efficient procedure for the analysis of the electromagnetic field problem coupled with the thermal diffusion one.

Optimal design of the microwave heating process using Neural Networks and Genetic Algorithms

The paper approaches the problem of modeling the microwave heating process using Neural Networks. The Neural Network was trained using Matlab and Comsol Multiphysics software. Numerical simulations were made in Comsol Multiphysics, obtaining the necessary input and output data to train the Neural Network. The training was made using Adaptive Neural Network tool from Matlab software.

The use of experimental design in order to optimize the heating parameters of wood material inside a microwave applicator. Experimental results

The present paper describes the optimization process of heating a dielectric material, inside a microwave applicator, using design of experiments. Based on the results achieved through optimization, experimental data were done using a microwave installation. The dielectric material used within the optimization process and experimental data is Fir wood, with initial humidity of 62%.

Optimal Solutions for Uniform Heating of a Non-Ferrous Bar by Electromagnetic Induction, Using Numerical Modeling

The paper intends to present the numerical modelling of the electromagnetic phenomena coupled with the thermal ones when processing the semi-finished products made up of non-ferrous alloy, through electromagnetic induction with the purpose of obtaining a homogenous heating of the pieces in the shortest time. The purpose of the numerical modelling in this paper is to check cheap solutions to homogenize the intensity of the magnetic field according to the geometry of the inductor, by using a magnetic field intensifier or if it is possible to use the motion of the pieces inside the inductor.

Numerical modeling of the electromagnetic and thermal fields in the process of uniform heating of half-products using magnetic flux concentrators

This paper presents some research results about the volume induction heating in order to obtain a uniform heating of half-products. Modern design tools, especially those using numerical modeling, offer several benefits [1]. The technological development of the heat-processing of the half-products imposes a quick heating and a uniform distribution of the thermal field inside the half-product. We present here the results of the numerical processing of the volume induction heating process for three optimized cases. The first two cases optimize the geometry of the inductor in order to obtain the most uniform induction heating along the length of the half-product. The third case produces the same results using a different method: here we use magnetic flux concentrators. These concentrators intensify the electromagnetic field, thus leading to better results when using induction heating [2], [3].

Researches regarding the transfer phenomenon of the electromagnetic and thermal fields in a system

In this paper we present aspects of the transfer of the electromagnetic and thermal field in a system. It is shown an application of numerical modeling 3D, using the method of the finite elements, for the study of the heating of some dielectrics with losses, of parallelepiped shape, situated in a applicator, excited with energy through a wave guide. It has the character of an applicative research, the obtained results being of practical use, with the main purpose of optimizing the functioning of some heating.

A new procedure for reconstructing the aged regions of the ferromagnetic bodies

Purpose – This paper presents an efficient procedure for reconstructing the aged region of ferromagnetic material.Design/methodology/approach – The aging of the ferromagnetic material leads to changes of B ‐H relationship. This property may be used for detection of the degraded parts of ferromagnetic pieces. In numerical procedures the region with a possible aged zone is described by a finite number of subdomains where the flaw vector is defined with binary entries.Findings – Because of the small B ‐H changes, the magnetic field modifications linearly depend (matrix T) by the flaw vectors. Using a double Gauss pivotation scheme, an enough well conditioned and invertible submatrix is extracted from the matrix T. The unknowns associated with this submatrix (called main unknowns) can be easily obtained by a linear relationship from the rest of the unknowns (called minor). In the set of the minor unknowns we search for that vector which gives the smallest error of the principal unknowns in comparison with the...