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Publications - 6383

On the asymptotic behavior of spatially implicit models of competition of two species with overcolonization

Éva V.P. Rácz Irma Szimjanovszki János Karsai

Publication Name: Dynamic Systems and Applications

Publication Date: 2014-01-01

Volume: 23

Issue: 4

Page Range: 677-690

Description:

We consider patch-based population dynamics, called metapopulations, and investigate the spread of two species and their competition for habitat areas. Let 0 ≤ p1,p2 denote the proportion (density) of the areas occupied by the species 1 and 2, respectively. Obviously, 0 ≤ p1 + p2 ≤ 1. Both species can locally extinct and colonize empty patches or patches occupied by the other with different rates. Hence the model is P1′ = κ1P1 (1 - P1 - P2) - e1p1p2-C1P1P2 - C2P1P2 P2′ = κ1P1 (1 - P1 - P2) - e1p1p2-C1P1P2 - C2P1P2 where ej are the extinction rates, κ1 are the rates of colonization of empty patches, and species "i" overcolonize "j" with the rate c1(i,j=1,2; i≠j) We investigate the asymptotic stability properties of the equilibria of such systems and we give a complete characterization of the parameter space. We prove that there can appear a globally asymptotically stable coexisting equilibrium. On the other hand, this equilibrium can become unstable and then the exclusive equilibria are only locally asymptotically stable. We have also developed dynamic applications in Wolfram Mathematica to illustrate our results.

Open Access: Yes

DOI: DOI not available

Restricting Digital Device Use in Schools: Comparative EU Policy Perspectives and a Hungarian Case Study

Enikő Kovács-Szépvölgyi Roland Kelemen Polett Koncsekné Reményi

Publication Name: Social Sciences

Publication Date: 2026-05-01

Volume: 15

Issue: 5

Page Range: Unknown

Description:

In recent years, several states have introduced restrictive measures regarding children’s use of digital devices in schools, shifting policy focus from digital literacy development towards prohibition and regulation. This study employs a comparative policy analysis to examine the regulation of ICT device use across EU member states, followed by a Hungarian case study focusing on a ministerial decree that restricted students’ access to digital devices. The social and educational implications are explored through an empirical survey-based study conducted among parents of children aged 6–18. The findings indicate that the regulation’s legitimacy is based on a general normative conviction rather than direct experience. The study reveals that a top-down policy, lacking broad social consensus and student participation, tends to function as a lex imperfecta (imperfect law) in practice, which in turn fosters a “hidden curriculum” of rule circumvention among students. We argue that such policies, by undermining the perceived legitimacy of rules, may unintentionally damage students’ long-term legal socialization and respect for norms. This suggests that effective regulation requires participatory approaches to build legitimacy, rather than relying solely on prohibition.

Open Access: Yes

DOI: 10.3390/socsci15050307

Synthesis of multiperiod heat exchanger networks: n-best networks with variable approach temperature

Ákos Orosz Rozália Lakner Bing Shen How Ferenc Friedler

Publication Name: Thermal Science and Engineering Progress

Publication Date: 2023-07-01

Volume: 42

Issue: Unknown

Page Range: Unknown

Description:

In industrial processes, the stream parameters of the heat exchanger network (HEN) synthesis problem can vary during different periods. As a result of the change in inlet and outlet temperatures and the flow rates of the streams, the optimal HEN and the optimal heat transfer areas of the heat exchangers can be different in each period. In our previous work, the standard HEN synthesis for minimum utility consumption was extended to consider varying stream parameters, where bypasses at the heat exchangers are used to ensure the exit streams meet the expected outlet temperatures. This requires optimization of the total annualized cost based on the maximal heat transfer areas of the heat exchangers for each period. Minimum approach temperature is applied to ensure that the areas of the heat exchangers stay within reasonable limits in the solution network. Since minimum approach temperature affects both the structure of the HEN and the total annualized cost, its value needs to be determined during the optimization procedure. The current work proposes a procedure for HEN synthesis which determines the best, n-best, or all feasible HENs for all periods considering variable approach temperature. The proposed method extends the P-graph-based HEN synthesis method for determining all feasible networks in all periods. Three case studies are used to demonstrate the application of the proposed method. The case studies show that while the commonly applied minimum approach temperature of 10 °C does indeed gives near-optimal results, some problems need different values, such as 25 °C or 30 °C.

Open Access: Yes

DOI: 10.1016/j.tsep.2023.101912

Customer sentiment analysis and prediction of halal restaurants using machine learning approaches

Mst Farjana Rahman Md Shamim Hossain Md Kutub Uddin Kamal Hossain

Publication Name: Journal of Islamic Marketing

Publication Date: 2023-06-07

Volume: 14

Issue: 7

Page Range: 1859-1889

Description:

Purpose: There is a strong prerequisite for organizations to analyze customer review behavior to evaluate the competitive business environment. The purpose of this study is to analyze and predict customer reviews of halal restaurants using machine learning (ML) approaches. Design/methodology/approach: The authors collected customer review data from the Yelp website. The authors filtered the reviews of only halal restaurants from the original data set. Following cleaning, the filtered review texts were classified as positive, neutral or negative sentiments, and those sentiments were scored using the AFINN and VADER sentiment algorithms. Also, the current study applies four machine learning methods to classify each review toward halal restaurants into its sentiment class. Findings: The experiment showed that most of the customer reviews toward halal restaurants were positive. The authors also discovered that all of the methods (decision tree, linear support vector machine, logistic regression and random forest classifier) can correctly classify the review text into sentiment class, but logistic regression outperforms the others in terms of accuracy. Practical implications: The results facilitate halal restaurateurs in identifying customer review behavior. Social implications: Sentiment and emotions, according to appraisal theory, form the basis for all interactions, facilitating cognitive functions and supporting prospective customers in making sense of experiences. Emotion theory also describes human affective states that determine motives and actions. The study looks at how potential customers might react to a halal restaurant’s consensus on social media based on reviewers’ opinions of halal restaurants because emotions can be conveyed through reviews. Originality/value: This study applies machine learning approaches to analyze and predict customer sentiment based on the review texts toward halal restaurants.

Open Access: Yes

DOI: 10.1108/JIMA-04-2021-0125

Parameter optimisation in fuzzy flip-flop-based neural networks

László Gál Rita Lovassy L. ászlóT Kóczy László T. Kóczy

Publication Name: International Journal of Reasoning Based Intelligent Systems

Publication Date: 2010-01-01

Volume: 2

Issue: 3-4

Page Range: 237-243

Description:

This paper presents a method for optimising the parameters of fuzzy flip-flop-based neural networks (FNN) consisting of fuzzy J-K and D flip-flop neurons based on various popular fuzzy operations using bacterial memetic algorithm with the modified operator execution order (BMAM). In early works, the authors proposed the Levenberg-Marquardt algorithm (LM) a widely used second order gradient type training algorithm for fuzzy neural networks variables optimisation. The BMAM local and global search evolutionary approach is a bacterial type memetic algorithm which executes several LM cycles during the bacterial mutation after each mutational step, using the LM method more efficiently. Numerical experiments were performed to show the function approximation capability of various quasi optimised FNN types based on fuzzy J-K and D flip-flop neurons using algebraic, Lukasiewicz, Yager, Dombi, Hamacher and Frank norms, trained with LM method and BMAM algorithm. © 2010 Inderscience Enterprises Ltd.

Open Access: Yes

DOI: 10.1504/IJRIS.2010.036869

Dynamics of Rolling Wheels with Elliptical Tread Profiles

Mate Antali Gabor Kupi

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 255-262

Description:

In this paper, the dynamics of a loose wheel is considered rolling on a horizontal plane, where the tread profile of the wheel is ellipsoidal. From the equations of motion, a two-parametric family of steady motions are obtained, corresponding to the rolling motion on a circular or straight line with a uniform rotational speed and tilt angle. It is shown that compared to the geometries analysed in the literature, the elliptical tread profile leads to a significant change in the qualitative behaviour of the wheel.

Open Access: Yes

DOI: 10.3233/ATDE240553

The long-term impact of COVID-19 on the physical activity, motor fitness, and maximum heart rate values of female university students

Ferenc Ihász Robert Podstawski Piotr Jurewicz Krzysztof Borysławski Jadwiga Snarska Attila Szabo

Publication Name: Biomedical Human Kinetics

Publication Date: 2026-01-01

Volume: 18

Issue: 1

Page Range: 12-23

Description:

Aim: This study examined the relationship between COVID-19 and the maximum heart rate (HRmax) achieved by female university students during maximal physical effort. It also analyzed how participants’ physical activity (PA) levels and anthropometric and physiological characteristics were related to HRmax 10 months after the World Health Organization (WHO) declared that COVID-19 was no longer a Public Health Emergency of International Concern. Materials and methods: Eighty-two female university students aged 19.0–28.0 years (21.23 ± 1.57) were assigned to three groups: G1 – 40 healthy participants, G2 – 29 participants with confirmed COVID-19, and G3 – 13 participants previously hospitalized due to COVID-19. Body composition was evaluated by bioelectrical impedance analysis. PA was assessed with the International Physical Activity Questionnaire, and HRmax was measured during the 12-min Cooper test performed on a rowing ergometer. Results: Healthy students (G1) showed the highest PA levels, followed by groups G2 and G3. Group G1 also exhibited more favorable body composition, with lower values of body mass, body mass index, waist-to-hip ratio, visceral fat, fat mass, fat-free mass, and skeletal muscle mass (p < 0.001). Maximum heart rate was highest in group G1 (175 beats per minute, bpm) and exceeded the values noted in groups G2 and G3 by 7 and 15 bpm, respectively (p = 0.028). Conclusions: Female students hospitalized due to COVID-19 had lower PA levels, reduced motor fitness, and worse body composition, which may explain their lower HRmax values observed 10 months after the pandemic.

Open Access: Yes

DOI: 10.2478/bhk-2026-0007

A Systematic Review of Life Cycle Assessment Reporting Practices and Transparency for Mono-Crystalline Silicon Photovoltaic Systems

Chew Tin Lee Kok Sin Woon Zhen Xin Phuang Kyle Sebastian Mulya Hong Sheng Loh Petar Sabev Varbanov

Publication Name: Chemical Engineering Transactions

Publication Date: 2025-01-01

Volume: 122

Issue: Unknown

Page Range: 97-102

Description:

Mono-crystalline silicon (mono-Si) PV modules account for around 70 % of global c-Si production, making robust environmental assessments essential. Life Cycle Assessment (LCA) is widely used for this purpose, yet inconsistent data reporting limits transparency and comparability. While prior reviews have explored environmental impacts and parameter trends, none have systematically evaluated reporting quality in mono-Si PV LCAs. To address this, the current review conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided review of 32 mono-Si PV LCA studies published from 2019 to 2024. Each was assessed using the ISO 14040/14044 framework and IEA guidelines, with a focus on key elements such as functional unit, system boundary, data sources, software, characterization models, and data quality analysis. The review applied both a descriptive summary of common practices and a grading rubric to evaluate reporting transparency. Results reveal major inconsistencies, with fewer than half of the studies meeting international standards. This underscores the urgent need for harmonized reporting protocols in mono-Si PV LCA literature.

Open Access: Yes

DOI: 10.3303/CET25122017

Improved energy management of capacitive energy storage in metro railcar by simulation

Istvan Szenasy

Publication Name: Renewable Energy and Power Quality Journal

Publication Date: 2010-04-01

Volume: 1

Issue: 8

Page Range: 757-762

Description:

This paper focuses on the use of modeling and simulation of a renewable energy. The capacitive energy storages contribute to the rapid energy recovery associated with regenerative braking in electric vehicles. This power system allows the acceleration and deceleration of the vehicle with a lower loss of energy. Short-distance passenger traffic on electrified lines is a domain where brake energy recuperation might reduce the total energy consumption significantly. In this paper the results of simulation models by Matlab-Simulink for an urban-metro railcar and some methods for reducing the needed value of capacitance by an improved energy management are presented. The aim of the new management of the energy storage system for decreasing the needed value of capacitance and improving the system performance is presented.

Open Access: Yes

DOI: 10.24084/repqj08.464