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Publications - 6374

On the existence and uniqueness of fixed points of fuzzy set valued sigmoid fuzzy cognitive maps

Istvan A. Harmati Laszlo T. Koczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2018-10-12

Volume: 2018-July

Issue: Unknown

Page Range: Unknown

Description:

Fuzzy cognitive maps are decision support tools, where the complex structure is modelled by a weighted, directed graph. The nodes represent specific characteristics of the modelled system, weighted and directed edges correspond to the direction and the strength of the relationship between the factors. The system state is identified by the values of the nodes which are computed by iteration. This process may lead to a fixed point, a limit cycle or produces chaotic behaviour. The type of behaviour depends on the weights, on the topology of the graph and on the function applied for the iteration. From the practical viewpoint, it is critical to know whether the iteration converges to a fixed point or not. In this article, we discuss this problem for the case when the weights or the values of the nodes are fuzzy numbers. This scenario may occur when linguistic variables, modelled by fuzzy numbers, describe the connections.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2018.8491447

Role of land use, green energy, and water resources for food accessibility: Evidence from emerging economies in the lens of COP28

Laszlo Vasa Shouhong Xie Waqas Amin Urszula Mentel

Publication Name: Land Degradation and Development

Publication Date: 2024-09-01

Volume: 35

Issue: 15

Page Range: 4607-4622

Description:

In the era of COP28, where most of the developed and developing economies concentrate more on the development of environmentally friendly energy resources to tackle the issue of climate change. Nevertheless, the literature lacks appropriate evidence regarding the influences of green energy and other resources on food security. This study analyses the influences of land use, green energy, and water resources on food accessibility in emerging economies, while also considering the important roles of natural resources, research and development (R&D) expenditure, and economic growth during 1980–2020. Due to non-linear data dispersion, the novel moments quantile regression is employed. Results assert that land use has a positive significant influence on food accessibility in the presence of water resources and a weaker negative impact in the presence of natural resources. Natural and water resources are detrimental to food accessibility in the Emerging Seven (E7) countries. Furthermore, R&D expenditure and green energy positively (negatively), while economic growth negatively (positively) impacted food accessibility in the presence of natural resources (water resources). The results are robust and validate causal inferences that help develop appropriate policies for emerging economies concerning food accessibility or security. In this rapidly evolving era, most empirical studies consider environmental quality. Conversely, this study contributes to the literature by examining the factors influencing food accessibility, as this issue is of considerable importance because of the rapidly growing global population.

Open Access: Yes

DOI: 10.1002/ldr.5244

Assessing logistics strategy issues under cognitive biases

Peter Foldesi Eszter Sós

Publication Name: 2023 14th IEEE International Conference on Cognitive Infocommunications Coginfocom 2023

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 141-146

Description:

Cognitive biases often appear in the decision-making process of highly qualified managers of companies because of the drive for efficiency and the time pressure in operation. There are also long-term strategic decisions where there is no longer time pressure, and yet cognitive bias appears, for example during the selection between the Push and Pull systems in logistics. The description of the actual situation has to be quantified because communication between human-machine systems, as defined in cognitive info-communication, is only viable if cognitive biases in decision-making can be considered properly. We propose fuzzy approach and measures that can assess whether the production uses a Push or Pull logistics strategy for a specific product or for the entire company.

Open Access: Yes

DOI: 10.1109/CogInfoCom59411.2023.10397543

The 'Model of Gyor': Triple Helix interactions and their impact on economic development

János Rechnitzer Petra Kecskés

Publication Name: Proceedings of the European Conference on Innovation and Entrepreneurship Ecie

Publication Date: 2015-01-01

Volume: 2015-January

Issue: Unknown

Page Range: 787-795

Description:

The authors will introduce Gyor as a significant member and centre both of this region and the Central European automotive industrial concentration. The study gives an overview of the emergence of the special Triple Helix Model in the analysed Hungarian town. Based on the results of the research programme 'Gyor Regional Vehicle Industrial District as a New Direction and Investment of Regional Development' (TÁMOP-4.2.2.A-11/1/KONV-2012-0010) completed in 2014, the authors will present the "Model of Gyor". The paper outlines the most significant theoretical and empirical results of the research which serves further development prospects, paths and examples to other Hungarian towns or to towns with similar industrial background around the world. The model represents the urban network structure as a 'living system' of Gyor that includes the university, the automotive industry and related innovative companies like Audi and the town (local government) as a coordinating factor.

Open Access: Yes

DOI: DOI not available

Parallel implementation of a combustion chamber simulation with MPI-OpenMP hybrid techniques

No authors available

Publication Name: MIPRO 2012 - 35th International Convention on Information and Communication Technology, Electronics and Microelectronics - Proceedings

Publication Date: 2012-08-22

Volume:

Issue:

Page Range: 356-361

Description:

The parallelization techniques utilized in a study of gas flow in a combustion chamber are described and discussed in this paper. Models of compressible fluid dynamics are solved with the finite volume method, and an additional algorithm, called "snapper" that handles piston and valve movement. In order to achieve an acceptable scaling on a CPU cluster with 240 cores, a two-stage parallelization with MPI in conjecture with OpenMP is implemented. For some types of physical investigations, the actual spatial region of interest is somehow changing, deforming, or moving in time in a predefined fashion. Handling gas dynamics with piston motion, even with the simplest models requires precaution. Apart from numerical and physical corrections, there are challenges, where multiple types of unstructured, and specially generated deforming grids are handled in a computer system with distributed memory. In the present work the results of the first implementations and benchmarks are presented, which prove to be well scaling for this modest-sized cluster. © 2012 MIPRO.

Open Access: No

DOI: DOI not available

Parametric approximation of fuzzy exponent for computationally intensive problems

No authors available

Publication Name: International Journal of Innovative Computing, Information and Control

Publication Date: 2012-08-01

Volume: 8

Issue: 8

Page Range: 5725-5744

Description:

The paper deals with the investigation of the critical non-linear factors and NP-hard problems of real-life decision-making processes. When using non-linear utility/objective functions to represent the value of various options in the search space or when NP-hard problems arise, often soft computing techniques must be applied for optimization. Many times significant uncertainty must be handled as well, so the use of fuzzy numbers can be an efficient method to cope with ambiguity and lack of information. The fuzzy extensions for heuristic based optimizing algorithms often face the problem of an increased number of calculations required to find the solutions. Appropriate representation of the fuzzy power function for non-linear cases is to be used so that it can keep the required computation time and resources at a reasonable level. © 2012 ICIC International.

Open Access: No

DOI: DOI not available

A bullwhip type of instability induced by time varying target inventory in production chains

No authors available

Publication Name: International Journal of Innovative Computing, Information and Control

Publication Date: 2012-08-01

Volume: 8

Issue: 8

Page Range: 5885-5897

Description:

We present an analytic investigation of the bullwhip effect developing in production-distribution chains. All common considered causes of the effect are excluded and the only mean to induce a bullwhip type of instability is the adoption of an inventory replenishment policy involving a variable target level. The policy is designed to maintain a safety stock that is proportional to the actual demand. In order to achieve our goals we develop a particular discrete model of supply chains by introducing some fresh concepts into the field of supply chain stability. The basic idea is to derive an update scheme describing the status of the whole chain over the entire time-space (period-stage) domain of interest. We prove that the strategy of demand driven target inventory inherently leads to an instability developing in the chain, which is precisely a manifestation of the bullwhip effect. Following the identification of the source and the nature of the instability, we propose a new production plan, which is stable and does not exhibit the bullwhip effect at all. Thus, the amplitude of the variation of the production rate never exceeds the amplitude of the oscillation of the market demand within the entire supply chain. © 2012 ICIC International.

Open Access: No

DOI: DOI not available

Alternating least squares for personalized ranking

Gabor Takacs Domonkos Tikk

Publication Name: Recsys 12 Proceedings of the 6th ACM Conference on Recommender Systems

Publication Date: 2012-10-17

Volume: Unknown

Issue: Unknown

Page Range: 83-90

Description:

Two avors of the recommendation problem are the explicit and the implicit feedback settings. In the explicit feedback case, users rate items and the user item preference relationship can be modelled on the basis of the ratings. In the harder but more common implicit feedback case, the system has to infer user preferences from indirect information: presence or absence of events, such as a user viewed an item. One approach for handling implicit feedback is to minimize a ranking objective function instead of the conventional prediction mean squared error. The naive minimization of a ranking objective function is typically expensive. This difficulty is usually overcome by a trade-off: sacrificing the accuracy to some extent for computational efficiency by sampling the objective function. In this paper, we present a computationally effective approach for the direct minimization of a ranking objective function, without sampling. We demonstrate by experiments on the Y!Music and Netix data sets that the proposed method outperforms other implicit feedback recommenders in many cases in terms of the ErrorRate, ARP and Recall evaluation metrics. Copyright © 2012 by the Association for Computing Machinery, Inc. (ACM).

Open Access: Yes

DOI: 10.1145/2365952.2365972

Virtual localization by blind persons

No authors available

Publication Name: AES: Journal of the Audio Engineering Society

Publication Date: 2012-07-01

Volume: 60

Issue: 7-8

Page Range: 568-579

Description:

Localization performance and spatial hearing abilities of blind persons are complex issues. In everyday life we rely on the "fact" that blind people can hear better, without thinking of what "better" means. Localization performance depends on many parameters such as properties of the excitation signal, environmental conditions, individual aspects, and visual influence. Our goal was to create a virtual environment aimed at helping the blind community use personal computers. In developing this environment we were concerned to cover technical and hearing related questions, as well as human factors. At first, this project included sighted subjects and basic properties of the virtual audio system and the applied HRTFs were tested. Subsequently, blind persons have been involved and comparative measurements performed using the same equipment and selected localization tasks. Twenty-eight blind person's localization performances were tested and compared with the results of 40 sighted subjects in a virtual audio environment. Blind subjects tended to be better in detecting movements in the horizontal plane around the head, localizing static frontal audio sources, and orientation in a 2-D virtual audio display. On the other hand, sighted subjects performed better identifying ascending sound sources in the vertical plane and detecting static sources in the back. In-the-head localization error rates and MAA results appeared to be about the same for both groups. The evaluation was also supported by some informal questions.

Open Access: No

DOI: DOI not available