And Elena-Madalina Ștefan

Dr. And Elena-Madalina Ștefan

orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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25 November 2023 in Computation
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Journal Article
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GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
MGMunteanu Mariana Gabriela
Munteanu Mariana Gabriela
GHEORGHE VOICUGHEORGHE VOICU
GHEORGHE VOICU
Gigel ParaschivGigel Paraschiv
Gigel Paraschiv
AȘAnd Elena-Madalina Ștefan
And Elena-Madalina Ștefan
The baking process in tunnel ovens can be influenced by many parameters. Among these, the most important can be considered as: the baking time, the volume of dough pieces, the texture and humidity of the dough, the distribution of temperature inside the oven, as well as the flow of air currents applied in the baking chamber. In order to obtain a constant quality of bakery or pastry products, and for the efficient operation of the oven, it is necessary that the solution made by the designers be subjected to modelling, simulation and analysis processes, before their manufacture, and in this sense it can be applied to the Computational Fluid Dynamics (CFD) numerical simulation tool. In this study, we made an analysis of the air flow inside the baking chamber of an oven. The analyzed oven was used very frequently on the pastry lines. After performing the modelling and simulation, the temperature distribution inside the oven was obtained in the longitudinal and transverse planes. For the experimental validation of the temperatures obtained in the computer-assisted simulation, the temperatures inside the analyzed electric oven were measured. The measured temperatures validated the simulation results with a maximum error of 7.6%.

23 May 2018 in 19th International Scientific Conference Engineering for Rural Development Proceedings
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AȘAnd Elena-Madalina Ștefan
And Elena-Madalina Ștefan
GHEORGHE VOICUGHEORGHE VOICU
GHEORGHE VOICU
GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
GIGeorge IPATE
George IPATE
MMMariana Munteanu
Mariana Munteanu

14 August 2024 in Applied Sciences
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Journal Article
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Alina Daiana IonescuAlina Daiana Ionescu
Alina Daiana Ionescu
Mariana FerdesMariana Ferdes
Mariana Ferdes
GHEORGHE VOICUGHEORGHE VOICU
GHEORGHE VOICU
GIGeorge IPATE
George IPATE
GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
MIHAELA BEGEAMIHAELA BEGEA
MIHAELA BEGEA
The current study evaluated the effect of powder fractionation based on particle size on the chemical composition of macronutrients such as proteins and sugars, on the phytochemical properties (total content of polyphenolic compounds, vitamin C, and antioxidant activity), on preservation capacity (water activity), powder functional properties (water absorption capacity and water solubility index), and physicochemical properties (particle size distribution and moisture content) of blackthorn berry (Prunus spinosa) powders. The fruits were separated from the plant material and seeds, dried, and then ground using an universal mill for dry materials. Eight fractions were obtained after sieving on sieves with different mesh sizes, such as 1 mm, 0.8 mm, 0.630 mm, 0.450 mm, 0.315 mm, 0.200 mm, and 0.125 mm. The grinding/sieving procedure was effective in separating Prunus spinosa powder into sufficiently different size classes. The maximal moisture content and water activity were 5.61% and 0.250, respectively, showed good preservation from a microbiological point of view, and ensured the prevention of oxidation of biologically active compounds of blackthorn berry powders. For samples with reduced particle sizes, the powder functional properties were greatly improved. The total phenolic content, carbohydrates, and antioxidant activity showed significantly different values for some particle size classes compared to the un-sieved sample. A considerable content of vitamin C was presented in the fraction with large particle sizes, precisely because they did not undergo intense degradation processes. Therefore, the technique of grinding and successive sieving proved effective in enhancing the physicochemical and functional characteristics of powdered blackthorn berries, particularly for smaller particles.

2 July 2024 in Agriculture
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BRBogdan Rosu
Bogdan Rosu
GHEORGHE VOICUGHEORGHE VOICU
GHEORGHE VOICU
GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
PTPaula Tudor
Paula Tudor
AȘAnd Elena-Madalina Ștefan
And Elena-Madalina Ștefan
This paper primarily presents statistics on the variation of physical characteristics (dimensions and mass) for the coulter discs of double-disc seeders. This statistic was calculated based on actual measurements of the probability density and cumulative probability for the mass of the discs, their average thickness, and outer diameter. These parameters (m = 4000 g, g = 4 mm, D = 380 mm) are tracked from the design phase to the actual realization phase, being the parameters specified in the purchase phase by users from agricultural machinery distributors. The standard deviation and deviation from the mean for a cumulative normal (Gaussian) distribution were calculated, and an analysis was made for the decrease of the mentioned parameters in discs already used for sowing cereals on an area of 80 hectares, due to the wear that appeared as a trace of the contact with the soil and the abrasive wear caused by it. Testing of disk parameters using both logarithmic and Gaussian distributions was performed, and test results are presented through appropriate graphs. With small deviations (which appeared for known or unknown reasons), it can be stated that the distribution of the mentioned parameters is generally a normal-type distribution. If the new discs are 15″ in diameter, experts recommend that they be replaced when they reach a diameter of less than 14.5 inches. This study can provide a reference for improving the physical characteristics of opener discs of seed drills in no-till conditions and beyond.

1 May 2021 in INMATEH Agricultural Engineering
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Journal Article
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PTPaula Tudor
Paula Tudor
GVGheorghe Voicu
Gheorghe Voicu
GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
AȘAnd Elena-Madalina Ștefan
And Elena-Madalina Ștefan
MMMariana-Gabriela Munteanu
Mariana-Gabriela Munteanu
VSVasilica Stefan
Vasilica Stefan
The Brabender farinograph is a device with which important indications for baking are obtained, namely: dough development time (DDT), water absorption (WA), dough stability time (DST), softening degree (SD), Farinograph Quality Number (FQN), important parameters for determining flour mixtures. These parameters are represented on the farinographic curve drawn during the farinograph test. Dough development or formation (formation of gluten) is represented by the ascending branch of the farinographic curve, which has a steep ascending slope, because time (expressed in minutes), fixed on the abscissa of the diagram, has relatively low values (about 1.2-3 min for regular flours), while consistency, fixed on the ordinate of the diagram, reaches the maximum value (peak time) of the dough. In comparison, the descending branch of the farinogram, which starts from the maximum value of the dough consistency (peak time), has a slow descending slope, because the kneading time is extended up to 20 minutes, and the consistency decreases relatively little. The paper presents the appreciation of this branch of the farinogram by mathematical equations for several types of doughs from wheat flour mixed with different percentages of salt.

17 July 2025 in Agriculture
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Alina Daiana IonescuAlina Daiana Ionescu
Alina Daiana Ionescu
GHEORGHE VOICUGHEORGHE VOICU
GHEORGHE VOICU
AȘAnd Elena-Madalina Ștefan
And Elena-Madalina Ștefan
GCGabriel-Alexandru Constantin
Gabriel-Alexandru Constantin
PTPaula Tudor
Paula Tudor
GMGheorghe Militaru
Gheorghe Militaru
Both the pulp and the seeds of rosehip are important for human health. Rosehip seeds are rich in polyunsaturated fats, which support a healthy skin membrane and protect it from inflammatory factors. In order to be used, the seeds require initial processing, mainly by grinding. This paper first presents a brief review of the physicochemical properties and the content of bioactive compounds in rosehip (Rosa canina) and its seeds. Original research results on the compression behavior of rosehip seeds are presented below, together with the key values of the most important parameters derived from the analysis. For seeds with a thickness ranging from 1.80 to 3.55 mm, the compressive force at the onset of fracture was recorded to be between 94.4 and 156.0 N, while the force required for complete fracture ranged from 114.0 to 495.0 N (with about 12.5% of values considered outside a normal distribution). Additionally, for these forces, the deformation of the seeds ranged between 0.142 and 0.916 mm at the onset of fracture and between 0.248 and 1.878 mm at complete fracture. For these characteristics, the energy consumed ranged between 0.012 and 0.041 J at the onset of fracture and between 0.017 and 0.322 J at complete breaking. The elasticity of the seeds also ranged between 159.9 and 789.1 N/mm, considering the forces and deformations at the onset of fracture. The results of our study contribute to expanding the database on the mechanical characteristics of rosehip seeds, knowledge of which is essential for the initial processing operations used in the pharmaceutical industry aimed at oil extraction.