CARMEN ELENA STOENOIU
@utcluj.ro
Department Electrical Machines and Drives/ Faculty of Electrical Engineering
Technical University of Cluj -Napoca
RESEARCH INTERESTS
management, economy, accounting
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Carmen Elena Stoenoiu and Lorentz Jäntschi
MDPI AG
The transition to a circular economy determines benefits at the level of each country by ensuring the premises for a sustainable economy in the future. The purpose of this study is to analyze indicators that measure the results of the implementation of circular economy through five study directions: Production and Consumption, Waste Management, Secondary Raw Materials, Competitiveness and Innovation, and Global Sustainability and Resilience. The analysis used 11 indicators that allow for the measurement of the evolution of eight Eastern European countries in the years 2012–2020. The study used three working hypotheses, which were all verified. The obtained results allowed for the classification of countries using a composite index and the grouping of countries with the help of cluster analysis using Pearson’s correlation coefficient. In a nutshell, sustainable development requires both economic development and environmental sustainability, and the developed composite index groups the countries’ evolution towards this goal.
G Thangkhenpau, Sunil Panday, Bhavna Panday, Carmen E. Stoenoiu, and Lorentz Jäntschi
American Institute of Mathematical Sciences (AIMS)
<abstract><p>In this paper, we have constructed a family of three-step methods with sixth-order convergence and a novel approach to enhance the convergence order $ p $ of iterative methods for systems of nonlinear equations. Additionally, we propose a three-step scheme with convergence order $ p+3 $ (for $ p\\geq3 $) and have extended it to a generalized $ (m+2) $-step scheme by merely incorporating one additional function evaluation, thus achieving convergence orders up to $ p+3m $, $ m\\in\\mathbb{N} $. We also provide a thorough local convergence analysis in Banach spaces, including the convergence radius and uniqueness results, under the assumption of a Lipschitz-continuous Fréchet derivative. Theoretical findings have been validated through numerical experiments. Lastly, the performance of these methods is showcased through the analysis of their basins of attraction and their application to systems of nonlinear equations.</p></abstract>
Carmen E. Stoenoiu, Mihai V. Putz, and Lorentz Jäntschi
Informa UK Limited
Carmen E. STOENOIU and Lorentz JÄNTSCHI
IEEE
Surprisingly or not, batteries were the primary source of electricity before the development of electric generators and electrical grids. Perhaps Voltaic pile was the first electrical battery that could continuously provide an electric current to a circuit, even if the electrochemical behavior of zinc and copper in a bimetallic arch, in contact with the electrolytes of muscle tissue were observed before. Ordinary batteries consist of one or more electrochemical cells. A cell is created by placing electrodes in an electrolyte where a chemical reaction either generates (at battery use) or uses (at battery recharging) an electric current. Here a very simple circuit has been used to provide raw data for estimating the electromotive force of a power source. The circuit has been used to measure pairs of potential versus intensity for three commercial batteries. From measured data three methods were employed to provide estimates of the internal resistance and electromotive force. The estimating of the internal resistances is discussed.
Carmen Elena Stoenoiu
MDPI AG
The need for sustainable development is a common concern for many countries, and the level reached by each country validates the efforts made and the effects of their associated well-being. In this study, an analysis of the indicators included in SDG-9 was performed, indicators that aim to achieve sustainable industrialization, increase research and innovation, and create a resilient infrastructure. The analysis used nine indicators that measure the situation of eight Eastern European countries during 2013–2019 to signal improvements or deteriorations in situations. The study used three working hypotheses that were verified and presented the evolution of countries in the aforementioned years. The results obtained led to the ranking of the countries by evaluating their economies from the perspective of the effects obtained by the method of sustainable development, thus categorizing the countries into ones with real, moderate, and low progress.
C E Stoenoiu, I Birou, C Cristea, and F M Serban
IOP Publishing
Abstract This study performs an exploratory analysis of the evolution of primary production of RES for EU28 countries over the ten years studied. Through the analysis, the document presents: the structure of production by sectors of production and by renewable energy sources, analyses the evolution of the mentioned indicators both in total and in detail on each renewable energy source and allows the identification of differences in the level of production from RES: between countries and regions. The analysis shows that these countries have implemented EU strategies in the field and exceeded the proposed target for 2020 starting from 2017. Among the most important RESs in primary energy production were the sources: Hydro, Wind and Solar, in the countries from the EU28 due to the existence of a natural potential that has been exploited and encouraged by the country-specific internal policies, but also due to the development of technologies and lower costs for these renewable energy sources.
C E Stoenoiu, M C Balan, F M Serban, and C Cristea
IOP Publishing
Abstract This study performs an exploratory analysis of the evolution of consumption of RES for EU28 countries over the ten years studied. Through the analysis, the document presents: the consumption by sectors of production and by renewable energy sources, analyses the evolution of consumption from RES: between countries and regions. Regarding the consumption of RES, it is increasing, reaching in 2017 compared to 2008 to increase by 147.8%.
Carmen-Elena Stoenoiu
IEEE
The study allows to know the evolution, for ten years, of the production in industry and of the energy consumption for the 27 countries of the EU. A comparative analysis was performed in which it can be seen how each country evolved, then the countries where the increase of production determined the increase of energy consumption were established, but also the countries where this connection is not direct. At the same time, the evolution of the production by activity sectors was determined, this allowing the knowledge of the sectors from each country that contribute to the achievement of the gross domestic product and of the economic well-being.
Ciprian Cristea, Maria Cristea, Radu-Adrian Tirnovan, Iulian Birou, Carmen Elena Stoenoiu, and Florica Mioara Serban
IEEE
Solar energy is one of the most important unlimited renewable energy sources that is becoming an increasingly used alternative to generate cleaner electricity. The efficiency of solar photovoltaic technologies has improved considerably, especially in the last decade. This study investigates the performance of a 6-kW grid-connected residential rooftop photovoltaic systems that are using various photovoltaic modules technologies, namely monocrystalline silicon, polycrystalline silicon, heterojunction with intrinsic thin layer, thin film copper indium gallium selenide, cadmium telluride and amorphous silicon for a residence in Romania. The results highlight that thin film copper indium gallium selenide technology is the most suitable in terms of monthly average performance ratio, while monocrystalline silicon panel is the most appropriate option in terms of ratio between produced electricity and occupied area. The findings of this paper are valuable for the stakeholders in establishing the photovoltaic modules technologies that are suitable for the investigated location or other zones with similar climatic characteristics.
Stoenoiu Carmen-Elena
IEEE
This study includes an analysis of resource and energy productivity indicators over ten years. Through these indicators it was possible to obtain the evolution of these indicators during the years studied as well as the differences between countries because of the achievements in those economies. The comparative analysis of the two indicators shows that the evolution trend is similar during 2019. Subsequently, a ranking of countries was made according to 5 indicators: Energy productivity, Resource productivity, Greenhouse gas emissions per capita and Eco innovation index. According to this ranking, it can be seen which are the countries that registered high values for the productivity and eco-innovation indicators and countries where the Greenhouse gas emissions per capita indicator registered decreasing values.
Carmen-Elena Stoenoiu
EDP Sciences
The analysis of the cost of production is a complex problem, being very useful in the planning and control process as well as in production and sales. In this study, this was done using three methods: accounting analysis, high-low and regression analysis that allowed cost elements to be identified through a cost equation that can be used in planning and control analysis or in sales activity. At the same time, the evolution of the cost elements was achieved using two estimates used by the accounting method. The High-Low method allowed the determination of the minimum and maximum activity level at one year's level, which was then analyzed through the company's available activity range. The multivariate regression analysis determined the analysis of the obtained model, being linear, thus establishing the production line.
Carmen-Elena Stoenoiu
EDP Sciences
The need for cost-volume-profit analysis (CVP) starts from the need to optimize and manage costs due to unforeseen events that accompany economic activity in all areas. In this paper, the dependency relationship between the three cost-volume-profit indicators was analyzed to highlight the need to permanently track and optimize these variables so that managers' decisions can be supported by adaptive analyzes to concrete needs. The study also includes a sensitivity analysis that has shown that the magnitude and meaning of changes occurring when changes occur to one or more variables may be different due to direct and inverse relationships that are established between these variables.
Carmen Elena Stoenoiu
Walter de Gruyter GmbH
Abstract In this paper a study was conducted on the complex integrated software that exists on the Romanian market. This consisted in identifying and analysing the size of the enterprise, the number of users, the technical characteristics determined by the type and number of modules included in the software and other information related to the implementation, according to the supplier's specifications. The primary analysis made it possible to obtain results regarding the integrated software market in Romania in terms of customer size, field of activity, software products that include the biggest number of modules. By statistical analysis using the multivariate cluster grouping exploration technique, the degree of similarity between the software and the modules was determined, calculating the distance by means of three measurement methods: the Euclidean distance, the percentage of disagreement, and the correlation coefficient 1- Pearson-r.
Lorentz JÄNTSCHI, Carmen Elena STOENOIU, and Sorana Elena BOLBOACMĂ
Springer Netherlands
Lorentz Jantschi, Carmen Elena Stoenoiu, and Sorana Daniela Bolboaca
IEEE
An e-assessment formative multiple-choice questions experience using an auto-calibrated system is presented. The testing system is briefly described, and the testing and grading methodology used to certify abilities and knowledge in microbiology and toxicology achieved by undergraduate students are presented. The development methodology applied to multiple-choice questions bank has been introduced. The students were actively implied in creation of the multiple-choice questions bank. The paper highlighted the relationship between learning and assessment. The results had been shown the efficiency and effectiveness of the proposed assessment system for both students and teacher.