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Found 6289 publications

Scheduling a forge with due dates and die deterioration

Máté Hegyháti Olivér Osz B. Ferenczi

Publication Name: Annals of Operations Research

Publication Date: 2020-02-01

Volume: 285

Issue: 1-2

Page Range: 353-367

Description:

In this paper a new scheduling problem is presented, which originates from the steel processing industry. The optimal scheduling of a steel forge is investigated with the goal of minimizing setup and storage costs under strict deadlines and special resource constraints. The main distinctive feature of the problem is the deterioration of some equipment, in this case, the so-called forging dies. While the aging effect has been widely investigated in scheduling approaches, where production speed decreases through time, durability deterioration caused by equipment setup has not been addressed yet. In this paper a mixed-integer linear programming model is proposed for solving the problem. The model uses a uniform discrete time representation and resource-balance constraints based on the resource–task network model formulation method. The proposed method was tested on 3-week long schedules based on real industrial scenarios. Computational results show that the approach is able to provide optimal short-term schedules in reasonable time.

Open Access: Yes

DOI: 10.1007/s10479-019-03336-6

Corporate Social Responsibility in the EU Regulation: With Special Focus on the SMEs

Adrienn Reisinger

Publication Name: Civil Szemle

Publication Date: 2024-09-18

Volume: 21

Issue: 4

Page Range: 111-131

Description:

The paper aims to introduce the milestones in the EU regulation on corporate social responsibility (CSR) in general with a special focus on small- and medium-sized enterprises (SMEs). EU regulation is introduced based on EU documents and international and Hungarian literature. The debate about CSR began in the 1990s in Europe and after the turn of the millennium several papers, guidelines, and directives attempt to provide a common approach about it. However, CSR relates mainly to big companies still today, smaller firms can also implement CSR. Despite that research on SMEs’ CSR started after 2000, EU documents already highlighted from the beginning of the 2000s the importance of smaller companies as well, and in 2002 the European Commission drew up a strategy for SMEs. The paper illustrates not only the papers and SMEs’ role but also provides ideas about the sense of the EU regulation on CSR and collects the reasons why could it be beneficial to have a debate and approach about CSR at the EU level. The paper also presents some information about how the SMEs’ CSR features comply with interview research among SMEs in Győr, Hungary in 2021–2022. It is possible to believe that learning the European approach may contribute to thinking in a more integrated way about how to behave socially responsibly and how to manage social impact.

Open Access: Yes

DOI: 10.62560/csz.2024.04.6

Vehicle Model for Driving Strategy Optimization of Energy Efficient Lightweight Vehicle

Péter Korös Zoltan Pusztai Ferenc Friedler

Publication Name: Chemical Engineering Transactions

Publication Date: 2021-01-01

Volume: 88

Issue: Unknown

Page Range: 385-390

Description:

The energy consumption and CO2 emission of urban vehicles are highly dependent on their operation. Vehicle models can be used for optimizing driving strategy for emission reduction. This paper proposes a novel vehicle model of a one-seat electric vehicle dedicated for Shell Eco-marathon (SEM), the most famous and largest race of energy efficient vehicles. The available vehicle dynamical formulas cannot be directly used to describe the characteristics of lightweight vehicles. In the current work, a novel grey-box vehicle model has been introduced, based on measurement scenarios. The whole model has been elaborated in MATLAB Simulink environment, where individual subassemblies were defined for driving resistance model, powertrain model, and the racetrack characteristics. The resistance force model manages the forces in straight line moving and also takes the effect of cornering into account. Based on test bench measurements the complete efficiency map of the drivetrain was created and implemented into the vehicle model. The presented vehicle model is suitable for driving strategy optimization. By optimizing this model, 7.1 % energy savings have been achieved compared to best human driven lap. Driving strategy optimization will be essential, especially for autonomous vehicles, expressing the importance of the presented results in the future.

Open Access: Yes

DOI: 10.3303/CET2188064

Fuzzy flip-flops revisited

Rita Lovassy László T. Kóczy

Publication Name: Advances in Soft Computing

Publication Date: 2007-12-01

Volume: 42

Issue: Unknown

Page Range: 643-652

Description:

J-K flip-flops are elementary digital units providing sequential features/memory functions. Their definitive equation is used both in the minimal disjunctive and conjunctive forms. Fuzzy connectives do not satisfy all Boolean axioms, thus the fuzzy equivalents of these equations result in two non-equivalent definitions, "reset and set type" fuzzy flip-flops (F3) by Hirota & al. when introducing the concept of F3. There are many alternatives for "fuzzifying" digital flip-flops, using standard, algebraic or other connectives. The paper gives an overview of some of the most famous F3-s by presenting their definitions and presenting graphs of the inner state for a typical state value situation. Then a pair of non-associative operators is introduced, and the properties of the respective F3 are discussed. The investigation of possible fuzzy flip-flops is continued by examining Türksen's IVFS, its midpoint values, and by introducing "minimized IVFS" (MIVFS), along with the MIVFS midpoints. © 2007 Springer-Verlag Berlin Heidelberg.

Open Access: Yes

DOI: 10.1007/978-3-540-72434-6_65

Numerical method for computer generated hologram

Lotfi Abdelhakim

Publication Name: Aip Conference Proceedings

Publication Date: 2007-10-23

Volume: 936

Issue: Unknown

Page Range: 351-355

Description:

The main purpose of this article is to develop a program package which generates artificial holograms by numerical methods and these computer generated holograms are numerically reconstructed. For the calculation of light propagation needed in the generation of holograms or in the reconstruction of the object from the hologram, we use two strategies, the first is the Fourier-based algorithm and the second uses finite difference discretization, and numerical tests that assess the accuracy of these algorithms are presented. © 2007 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.2790149

CONDITION ASSESSMENT OF SIDE CORRIDORS WITH THE USE OF AGGREGATIONS BASED ON FUZZY INFERENCE METHOD

No authors available

Publication Name: REHABEND

Publication Date: 2022-01-01

Volume:

Issue:

Page Range: 864-872

Description:

Professional maintenance of the residential building stock and completion of the necessary renovation works on time will increase the life of the residential buildings and improve their condition. For this reason, it is important to create and apply condition assessment and decision support systems that uniformly and accurately determine the condition of individual building structures and buildings. Thus, the necessary interventions -taking into account the available financial resources-can be performed at the right time and in the right way. The ultimate goal of our research is to develop a decision support system that evaluates the damage of individual structural members and determines the condition of each load bearing structure, ultimately evaluating the entire building. It then suggests (if necessary) which of the available renovation methods to choose. In addition to the damage of the load bearing structures, the decision among the proposed methods of reinforcement is also influenced by architectural requirements and economic aspects. In the present phase of the research we have developed a method that determines the condition of side corridor structures based on the observed damage detected by visual building diagnostics (e.g. steel cantilever corrosion, stone plate cracks, stone plate abrasion). The side corridors are divided into three well-separable structural elements (cantilever, plate, balustrade) and their damage is analyzed separately. Qualification is made by a fuzzy signature based decision making system. In this, aggregations are based on classical fuzzy inference methods. The rule bases of the aggregation were constructed during this research. The final condition of the side corridor structure is affected by the combined condition of the three structural elements.

Open Access: No

DOI: DOI not available

An efficient evolutionary metaheuristic for the traveling repairman (Minimum latency) problem

Peter Foldesi Boldizsar Tuu-Szabo László T. Kóczy

Publication Name: International Journal of Computational Intelligence Systems

Publication Date: 2020-01-01

Volume: 13

Issue: 1

Page Range: 781-793

Description:

In this paper we revisit the memetic evolutionary family of metaheuristics, called Discrete Bacterial Memetic Evolutionary Algorithm (DBMEA), whose members combine Furuhashi’s Bacterial Evolutionary Algorithm and various discrete local search techniques. These algorithms have proven to be efficient approaches for the solution of NP-hard discrete optimization problems such as the Traveling Salesman Problem (TSP) with Time Windows. This paper presents our results in solving the Traveling Repairman Problem (also called Minimum Latency Problem) with a DBMEA variant. The results are compared with state-of-the-art heuristics found in the literature. The DBMEA in most cases turned out to be faster than all other methods, and for the bigger benchmark instances it was also found to have better solutions than the former best-known results. Based on these test results we claim to have found the best approach and thus we suggest the use of the DBMEA for the Traveling Repairman Problem, especially for large instances.

Open Access: Yes

DOI: 10.2991/ijcis.d.200529.001

Economic development and growth in central and Eastern Europe

Csilla Polster

Publication Name: Comparative Economic Research

Publication Date: 2021-01-01

Volume: 24

Issue: 4

Page Range: 69-84

Description:

The study investigates the economic growth in Central and Eastern Europe in the last 25 years. The economy can be regarded as a substantial topic in any country, but it is even more interesting in developing countries. One of the basic ideas of the European Union is the convergence between member states, namely the reduction of development disparities, which can be achieved through faster economic growth in less-developed countries. Growth theory is one of the main topics in economics. Its significant importance is because the desire for development is one of the main driving forces of mankind. The aim of the study is to reveal the crucial differences and common features between the growth paths of the eleven Central and Eastern European member states of the European Union. After presenting growth theories, the growth performance of the examined Central and Eastern European member states is pinpointed. During the research, GDP per capita, population, migration, activity rate, employment rate, unemployment rate, foreign direct investment and foreign trade openness are considered.

Open Access: Yes

DOI: 10.18778/1508-2008.24.31

Social media communication of the spa industry during the four waves of the COVID-19 pandemic

Roland Zsolt Szabó Veronika Keller Erzsébet Printz-Markó

Publication Name: Journal of International Studies

Publication Date: 2023-01-01

Volume: 16

Issue: 4

Page Range: 97-116

Description:

Tourism and the spa industry have been heavily affected by the Covid-19 pandemic. The social media strategies of top spa destinations were studied during the period from March 1, 2020, through February 28, 2022. Together There are 2,539 posts of selected spas (from Iceland, Austria, Slovakia, and Hungary). Based on former research, four major themes emerged: (i) Facebook versus Instagram communication during the two years of the pandemic; (ii) Live Vividness of the social media communication; (iii) Activity of the followers; (iv) Use of hashtags. Findings show that social media plays a significant role in fighting against the negative impacts of a crisis. Communication on social media is especially effective when emotional, affective images and positive emotions are presented to the target customers. Our findings extend not only crisis management theory, but also provide valuable insights into tourists’ psychometrics, which is essential for tourism destinations in developing their communication strategies.

Open Access: Yes

DOI: 10.14254/2071-8330.2023/16-4/7