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
In the current era, the economic model that measures the dependence of the training offered by companies to their employees on certain variables allows for identifying the steps taken on account of digital transformations, given the fact that companies want to be competitive, to develop sustainably and the positive effect to it spreads globally. However, how digital transformation contributes remains unclear in both the literature and practice. Five descriptors of information on the economy in relation to the digital economy were extracted from the Eurostat database, and data on eight Eastern European countries in the period 2012–2020 served as primary data in the analysis. A generalized linear model was used as a statistical tool to infer the data series. Following the statistical regression analysis, it was found that the variable measuring the share of companies that offered training for the development/improvement of information and communication technology (ICT) skills is influenced by the combined effect of several other variables: ‘country’, ‘country × year’, ‘country × share of ICT personnel in total employees’, year × “share of ICT sector in GDP”. Based on the results, we noticed that the studied countries are included in two groups with distinct features, which influence the obtained GLZ model, showing the increase in the dependency effect or, on the contrary, the decrease in this effect.
Carmen Elena Stoenoiu and Lorentz Jäntschi
MDPI AG
Approaches to the sustainable development of enterprises are a continuous concern of EU countries, contributing to the achievement of national well-being. Companies today face the combined effects of a multitude of factors that affect their results. This study was carried out to analyse the factors that influence the enterprises in the non-financial sector (industry, trade, and services). The analysis used the related data from eight Eastern European countries in the period of 2018–2020, and includes companies by country, size, number of employees, number of companies by number of employees, turnover, added value and average productivity per employee in generating turnover and added value, respectively. To carry out the study, four research questions and four possible hypotheses were used. For data analysis, generalized linear models were used, and four models were obtained and statistically validated. The obtained results led to the identification of the factors associated with the dependent variables that were the basis for the creation of the models.
S. Panday, Shubham Kumar Mittal, C. Stoenoiu and L. Jäntschi
In this article, we introduce a novel three-step iterative algorithm with memory for finding the roots of nonlinear equations. The convergence order of an established eighth-order iterative method is elevated by transforming it into a with-memory variant. The improvement in the convergence order is achieved by introducing two self-accelerating parameters, calculated using the Hermite interpolating polynomial. As a result, the R-order of convergence for the proposed bi-parametric with-memory iterative algorithm is enhanced from 8 to 10.5208. Notably, this enhancement in the convergence order is accomplished without the need for extra function evaluations. Moreover, the efficiency index of the newly proposed with-memory iterative algorithm improves from 1.5157 to 1.6011. Extensive numerical testing across various problems confirms the usefulness and superior performance of the presented algorithm relative to some well-known existing algorithms.
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.
Carmen Elena Stoenoiu and Lorentz Jäntschi
EnPress Publisher
Using multiple evaluation methods and systems give a comprehensive assessment. A computer-based multiple-choice assessment system was designed, implemented, posted online, and used to assess students as part of their final evaluation marks for a discipline. The online system of evaluation was intended to be used multiple times for evaluating the assimilation degree of a specific course at the end of the course. The data recorded for the period 2017–2023 with about 1400 distinct users were used to analyze the performance of the evaluation system. The system worked fine and a slight modification of it served well on remote evaluation during COVID-19 period. However, the upturn of mobile phone applications requires the creation of a system adapted to the new virtual reality.
Carmen E. Stoenoiu and Lorentz Jäntschi
Springer Nature Switzerland
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 Elena Stoenoiu and Lorentz Jäntschi
IEEE
The current trend in energy sources is towards the large-scale use of small-scale photovoltaic (PV) systems for local energy supply. The today's common commercial PV systems today include PV cells of various manufactures and origins based mostly on a large-area p-n junction made of silicon. The characteristic equation describes the non-linear dependence between current and voltage and the parameters values of the characteristic equation define the working regime of the PV system. Parameters identification involves a series of iterations in which the sum of squared errors is minimized (and thus the chance of observation is maximized). A large number of iterations are required if the optimization follows the usual course from the solution proposed by the vertical offsets to the perpendicular offsets. In the present work, an intermediate solution is used to speed up the convergence.
Carmen Elena Stoenoiu and Lorentz Jäntschi
IEEE
A computer based multiple choice multiple answers evaluation system has been designed, implemented, posted online and used to evaluate students on general chemistry for the last 10 years. In this paper, the design, implementation, and some results regarding the students' performances are presented and discussed.
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.
F. M. Șerban, Romania Drives and C. Stoenoiu
This article analyses data on general government expenditure, at the level of the European Union (EU 28) according to the Classification of the Functions of Government – COFOG over the 2008-2017 period. Data shows that the expenditures increased at the beginning of the economic crisis in all EU countries, being followed by a slowdown in expenditures growth. All countries have adopted policies in order to reduce government expenditures towards the end of the period, aiming to increase their efficiency. Usually in high-income countries, compared with low-income countries, government expenditures are much larger as percent of gross domestic product (GDP), but the relations are not very strong though.
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