István Harmati

55838510758

Publications - 55

Breast Cancer Surgical Specimens: A Marking Challenge and a Novel Solution—A Prospective, Randomized Study

R. Rajnai István Harmati Dániel Kollár Noemi Kranitz András Drozgyik Tamás F. Molnar Tamás Szabó

Publication Name: Biomedicines

Publication Date: 2025-04-01

Volume: 13

Issue: 4

Page Range: Unknown

Description:

Background: Accurate orientation of resected breast specimens is essential for proper pathological evaluation and margin assessment. Misorientation may compromise analysis, lead to imprecise re-excisions, and increase the risk of local recurrence. This study aims to evaluate a novel specimen plate designed to maintain consistent tissue orientation and compares its effectiveness to traditional suture marking. Methods: In a single-center, prospective, randomized two-arm trial, 56 specimens were oriented with the new plate and 54 with conventional sutures. Outcomes included intraoperative imaging interpretation, specimen handling, and pathological assessment, with a focus on orientation accuracy and margin evaluation. Results: The specimen plate significantly reduced misorientation (p < 0.01) and improved interpretation during intraoperative imaging. Pathologists reported greater ease in identifying direction and tumor-free zones, leading to a more accurate margin assessment. Non-R0 resections requiring re-excision were fewer with the specimen plate (8.9%) compared to suture marking (22.2%). Conclusions: The newly developed specimen plate can offer a reliable solution for improving specimen orientation in breast cancer surgery; however, further validation in multicenter studies is needed to confirm its applicability across diverse surgical settings. By ensuring consistent orientation and enhancing diagnostic interpretation, it may help reduce re-excisions and improve patient safety.

Open Access: Yes

DOI: 10.3390/biomedicines13040984

Non-Palpable Breast Cancer: A Targeting Challenge–Comparison of Radio-Guided vs. Wire-Guided Localization Techniques

István Harmati Dániel Kollár András Drozgyik Tamás F. Molnar Levente Dankházi Krisztina Szalay

Publication Name: Biomedicines

Publication Date: 2024-11-01

Volume: 12

Issue: 11

Page Range: Unknown

Description:

Background: The incidence of non-palpable breast cancer is increasing due to widespread screening and neo-adjuvant therapies. Among the available tumor localization techniques, radio-guided occult lesion localization (ROLL) has largely replaced wire-guided localization (WGL). The aim of this study was to compare the ROLL and WGL techniques in terms of the effectiveness of isotopic marking of axillary sentinel lymph nodes and to assess patient perspectives along with surgeon and radiologist preferences. Methods: A single-center, prospective, randomized study enrolled 110 patients with non-palpable breast lesions (56 ROLL, 54 WGL). Breast type, tumor volume, location, histological and radiological features, and localization/surgical duration were evaluated in the context of sentinel lymph node marking using isotope (technetium-99m-labeled human serum albumin) and blue dye. Statistical analysis was performed with significance set at p < 0.05 and strong significance at p < 0.01. Results: A single-center, prospective, randomized study enrolled 110 patients with non-palpable breast lesions (56 ROLL, 54 WGL). Breast type, tumor volume, location, histological and radiological features, and localization/surgical duration were evaluated in the context of sentinel lymph node marking using isotope (technetium-99m-labeled human serum albumin) and blue dye. Statistical analysis was performed with significance set at p < 0.05 and strong significance at p < 0.01. Conclusions: While ROLL provided advantages in terms of patient comfort and logistical simplicity, WGL was superior for axillary sentinel lymph node marking, particularly in inner quadrant tumors, suggesting that WGL may be preferred in these cases.

Open Access: Yes

DOI: 10.3390/biomedicines12112466

Wasserstein distance for OWA operators

Lucian Coroianu István Harmati Robert Fullér

Publication Name: Fuzzy Sets and Systems

Publication Date: 2024-05-15

Volume: 484

Issue: Unknown

Page Range: Unknown

Description:

We suggest a distance measure for OWA operators. First we associate an OWA operator with a unique regular increasing monotone quantifier and then define the distance between two OWA operators as the Wasserstein-1 distance between their associated quantifiers.

Open Access: Yes

DOI: 10.1016/j.fss.2024.108931

The median under orness

Lucian Coroianu István Harmati Robert Fullér

Publication Name: Fuzzy Sets and Systems

Publication Date: 2024-04-01

Volume: 481

Issue: Unknown

Page Range: Unknown

Description:

Besides the mean, the median is the most widely used single-valued descriptor of data sets. It is well-known that the orness level of the median operator is 1/2. In this paper we provide approximations of the median operator under a given level of orness. We find the exact optimal weighting vector for the 1-norm approximation problem in all conceivable cases and for 2-norm approximation up to nine aggregates. The analytical results show that if the orness level is not 1/2, then not only the middle, but the extreme values also matter.

Open Access: Yes

DOI: 10.1016/j.fss.2024.108901

Fuzzy Cognitive Maps: Mathematical Challenges

István Harmati

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2024-01-01

Volume: 427

Issue: Unknown

Page Range: 95-103

Description:

Although the applications of fuzzy cognitive maps cover a wide variety of scientific and engineering fields, the deep theoretical analysis of their behaviour has a much more weaker literature. In this chapter, first we introduce a more compact description of the updating rule, which makes the further mathematical investigations easier. Then several examples of different qualitative behaviour are shown, highlighting the importance of the strict mathematical discussion of this problem. Finally, the main mathematical factors regarding the behaviour of fuzzy cognitive maps and its extensions will be introduced.

Open Access: Yes

DOI: 10.1007/978-3-031-37959-8_8

Dynamics of Classical Fuzzy Cognitive Maps

István Harmati

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2024-01-01

Volume: 427

Issue: Unknown

Page Range: 105-119

Description:

In Fuzzy Cognitive Map based modelling, the final conclusion is based on the assumption that the system reaches an equilibrium point (fixed point) after a certain number of iteration. It is not straightforward that this leads to a fixed point, since the iteration may show various dynamical behaviours: multiple fixed points, limit cycle and unpredictable patterns may also occur. In this chapter, a gentle insight into the dynamics of FCMs’ is provided based on solid mathematical tools. We prove sufficient conditions for the existence and uniqueness of fixed points for sigmoid, hyperbolic tangent and rescaled sigmoid FCMs, which are also necessary in the case of the latter two. Additionally, symmetrical properties of fixed points and basins of attraction of hyperbolic tangent and rescaled sigmoid FCMs are also introduced with mathematical proof.

Open Access: Yes

DOI: 10.1007/978-3-031-37959-8_9

Dynamics of Fuzzy Cognitive Maps with Uncertain Weights

István Harmati

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2024-01-01

Volume: 427

Issue: Unknown

Page Range: 121-133

Description:

In real-life problems, the weights of the connections between the concepts are often not known exactly. This uncertainty can be modelled in different ways, based on different considerations. In this chapter, we discuss two models, regarding the nature of uncertainty. Fuzzy grey cognitive maps (FGCMs) employ grey system theory to represent vagueness of the causal connections. This approach assumes that we do know the range of the unknown weight, but within this range we do not have any further information. In other words, the model assumes known extension, but unknown intension. In classical fuzzy cognitive maps the weights are single numbers, so the fuzziness is not present there. Fuzzy set valued fuzzy cognitve maps handle this known issue by assigning fuzzy sets to the connections, so in this model the intension of a weight is known, but the extension is not exactly clear. These models behave somewhat similarly to classical fuzzy cognitive maps. The final conclusion about the modelled system is based on the limiting behaviour of the iteration process. This iteration may converge to an equilibrium point, may arrive to limit cycles or may produce unstable behaviour. In this chapter, sufficient conditions for the existence and uniqueness of fixed points of fuzzy grey and fuzzy set valued FCMs are provided.

Open Access: Yes

DOI: 10.1007/978-3-031-37959-8_10

OWA operators in the insurance industry

István Harmati Dávid Fülep Krisztián Koppány Norbert Kovács

Publication Name: Journal of Infrastructure Policy and Development

Publication Date: 2024-01-01

Volume: 8

Issue: 13

Page Range: Unknown

Description:

In this paper, we examine a possible application of ordered weighted average (OWA for short) aggregation operators in the insurance industry. Aggregation operators are essential tools in decision-making when a single value is needed instead of a couple of features. Information aggregation necessarily leads to information loss, at least to a specific extent. Whether we concentrate on extreme values or middle terms, there can be cases when the most important piece of the puzzle is missing. Although the simple or weighted mean considers all the values there is a drawback: the values get the same weight regardless of their magnitude. One possible solution to this issue is the application of the so-called Ordered Weighted Averaging (OWA) operators. This is a broad class of aggregation methods, including the previously mentioned average as a special case. Moreover, using a proper parameter (the so-called orness) one can express the risk awareness of the decision-maker. Using real-life statistical data, we provide a simple model of the decision-making process of insurance companies. The model offers a decision-supporting tool for companies.

Open Access: Yes

DOI: 10.24294/jipd8015

Global stability of fuzzy cognitive maps

F. Hatwágner István Harmati L. T. Koczy

Publication Name: Neural Computing and Applications

Publication Date: 2023-04-01

Volume: 35

Issue: 10

Page Range: 7283-7295

Description:

Complex systems can be effectively modelled by fuzzy cognitive maps. Fuzzy cognitive maps (FCMs) are network-based models, where the connections in the network represent causal relations. The conclusion about the system is based on the limit of the iteratively applied updating process. This iteration may or may not reach an equilibrium state (fixed point). Moreover, if the model is globally asymptotically stable, then this fixed point is unique and the iteration converges to this point from every initial state. There are some FCM models, where global stability is the required property, but in many FCM applications, the preferred scenario is not global stability, but multiple fixed points. Global stability bounds are useful in both cases: they may give a hint about which parameter set should be preferred or avoided. In this article, we present novel conditions for the global asymptotical stability of FCMs, i.e. conditions under which the iteration leads to the same point from every initial vector. Furthermore, we show that the results presented here outperform the results known from the current literature.

Open Access: Yes

DOI: 10.1007/s00521-021-06742-9

Preface

María Eugenia Cornejo István Harmati L. T. Koczy Jesús Medina-Moreno

Publication Name: Studies in Computational Intelligence

Publication Date: 2023-01-01

Volume: 1040

Issue: Unknown

Page Range: v-ix

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Best approximation of OWA Olympic weights under predefined level of orness

Lucian Coroianu István Harmati Robert Fullér

Publication Name: Fuzzy Sets and Systems

Publication Date: 2022-11-05

Volume: 448

Issue: Unknown

Page Range: 127-144

Description:

An ideal type of OWA aggregation operator is the one constructed on the so-called Olympic weights. The orness of this operator is 1/2. Therefore, sometimes we need a trade-off between the desire of having an OWA aggregation operator with weights as close as possible to the Olympic ones and the desire of having a predefined level of orness. In this paper, we choose these optimal weights by minimizing the Euclidean distance to the Olympic weights vector under the constraint of preserving a given level of orness. First, in the case n=4, we propose an iterative algorithm where the optimal solution is given for all possible values of the orness, values that are grouped along a partition of the unit interval. This iterative algorithm will inspire us to deduce the optimal weights in the general case. Consequently, we will obtain the analytical solution of the optimal weights as a function depending on the orness level.

Open Access: Yes

DOI: 10.1016/j.fss.2022.07.009

On stability of maximal entropy OWA operator weights

István Harmati I. Felde Robert Fullér

Publication Name: Fuzzy Sets and Systems

Publication Date: 2022-11-05

Volume: 448

Issue: Unknown

Page Range: 145-156

Description:

The maximal entropy OWA operator (MEOWA) weights can be obtained by solving a nonlinear programming problem with a linear constraint for the level of orness. Since the exact MEOWA weights are not known for the general case we can only find approximate solutions. We will prove that the nonlinear programming problem for obtaining MEOWA weights is well-posed: it has a unique solution and each MEOWA weight changes continuously with the initial level of orness. Using the implicit function theorem we will show that MEOWA weights are Lipschitz-continuous functions of the orness level. The stability property of the MEOWA weights under small changes of the orness level guarantees that small rounding errors of digital computation and small errors of measurement of the orness level can cause only a small deviation in MEOWA weights, i.e. every successive approximation method can be applied to the computation of the approximation of the exact MEOWA weights.

Open Access: Yes

DOI: 10.1016/j.fss.2022.01.003

Some Dynamical Properties of Higher-Order Fuzzy Cognitive Maps

István Harmati L. T. Koczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2022-01-01

Volume: 959

Issue: Unknown

Page Range: 149-156

Description:

Fuzzy cognitive maps are recurrent neural networks, applied for modelling and simulation of complex dynamic systems. They have been successfully applied to many engineering problems. The conclusion about the system depends on the mathematical behaviour of an iteration, namely, a first-order recursion. The first-order dynamics have some limitations since it takes into account only the previous time step. To overcome these limitations higher-order memory-based fuzzy cognitive maps have been introduced, which use a sequence of preceding states to determine the next one. In this paper, some dynamical properties of higher-order fuzzy cognitive maps are analyzed. Particularly, the existence and uniqueness of equilibrium points and the stability are discussed.

Open Access: Yes

DOI: 10.1007/978-3-030-74970-5_17

Probability-based Vendor Selection Model for the Hungarian Automotive Supply Network

István Harmati Ákos Dömötörfi Zoltan Andras Nagy

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2022-01-01

Volume: 50

Issue: 2

Page Range: 216-222

Description:

The aim of this paper is to investigate the structure of the Hungarian automotive supply network and provide a possible solution that mathematically describes the connections between the interested parties. In the study an approximate model is introduced to determine the links between hubs (car manufacturers), nodes (Tier1 suppliers) and edges, combining probability random graph and scale free network theory. During the simulation some main drivers were applied for selection purposes, such as location, turnover, product profile. As a result of the study a potential tool has been designed to support decision-making.

Open Access: Yes

DOI: 10.3311/PPtr.17966

Preface

María Eugenia Cornejo István Harmati Eloísa Ramírez-Poussa Juan Moreno-García L. T. Koczy Jesús Medina-Moreno

Publication Name: Studies in Computational Intelligence

Publication Date: 2022-01-01

Volume: 955

Issue: Unknown

Page Range: v-viii

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Dynamics of fuzzy-rough cognitive networks

István Harmati

Publication Name: Symmetry

Publication Date: 2021-05-01

Volume: 13

Issue: 5

Page Range: Unknown

Description:

Fuzzy-rough cognitive networks (FRCNs) are interpretable recurrent neural networks, primarily designed for solving classification problems. Their structure is simple and transparent, while the performance is comparable to the well-known black-box classifiers. Although there are many applications on fuzzy cognitive maps and recently for FRCNS, only a very limited number of studies discuss the theoretical issues of these models. In this paper, we examine the behaviour of FRCNs viewing them as discrete dynamical systems. It will be shown that their mathematical properties highly depend on the size of the network, i.e., there are structural differences between the long-term behaviour of FRCN models of different size, which may influence the performance of these modelling tools.

Open Access: Yes

DOI: 10.3390/sym13050881

Notes on the rescaled algorithm for fuzzy cognitive maps

István Harmati L. T. Koczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2020-01-01

Volume: 819

Issue: Unknown

Page Range: 43-49

Description:

Fuzzy Cognitive Maps are network-like decision support tools, where the final conclusion is determined by an iteration process. Although the final conclusion relies on the assumption that the iteration reaches a fixed point, it is not straightforward that the iteration will converge to anywhere, since it can produce limit cycles or chaotic behaviour also. In this paper, we briefly analyse the behaviour of the so-called rescaled algorithm for fuzzy cognitive maps with respect to the existence and uniqueness of fixed points.

Open Access: Yes

DOI: 10.1007/978-3-030-16024-1_6

On the convergence of fuzzy grey cognitive maps

István Harmati L. T. Koczy

Publication Name: Advances in Intelligent Systems and Computing

Publication Date: 2020-01-01

Volume: 945

Issue: Unknown

Page Range: 74-84

Description:

Fuzzy grey cognitive maps (FGCMs) are extensions of fuzzy cognitive maps (FCMs), applying uncertain weights between the concepts. This uncertainty is expressed by so-called grey numbers. Similarly to FCMs, the inference is determined by an iteration process, which may converge to an equilibrium point, but limit cycles or chaotic behaviour may also turn up. In this paper, based on the grey weighted connections between the concepts and the parameter of the sigmoid threshold function, we give sufficient conditions for the existence and uniqueness of fixed points for sigmoid FGCMs.

Open Access: Yes

DOI: 10.1007/978-3-030-18058-4_6

Stability of fuzzy cognitive maps with interval weights

István Harmati L. T. Koczy

Publication Name: Proceedings of the 11th Conference of the European Society for Fuzzy Logic and Technology Eusflat 2019

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 756-763

Description:

In fuzzy cognitive maps (FCMs) based modelling paradigm, the complex system's behaviour is gathered by the causal connections acting between its main characteristics or subsystems. The system is represented by a weighted, directed digraph, where the nodes represent specific subsystems or features, while the weighted and directed edges express the direction and strength of causal relations between them. The state of the complex system represented by the so-called activation values of the nodes, that is computed by an iterative method. The FCM based decision-making relies on the assumption that this iteration reaches an equilibrium point (fixed point), but other types of behaviour, namely limit cycles and chaotic patterns may also show up. In practice, the weights of connections are estimated by human experts or machine learning methods. Both cases have their own uncertainty, which can be represented by using intervals as weights instead of crisp numbers. In this paper, sufficient conditions are provided for the existence and uniqueness of fixed points of fuzzy cognitive maps that are equipped with interval weights, which also ensure the global asymptotic stability of the system.

Open Access: Yes

DOI: DOI not available

On the Convergence of Input-Output Fuzzy Cognitive Maps

István Harmati L. T. Koczy

Publication Name: Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics

Publication Date: 2020-01-01

Volume: 12179 LNAI

Issue: Unknown

Page Range: 449-461

Description:

Fuzzy cognitive maps are recurrent neural networks, where the neurons have a well-defined meaning. In certain models, some neurons receive outer input, while other neurons produce the output of the system. According to this observation, some neurons are categorized as input neurons and the others are the state neurons and output neurons. The output of the system is provided as a limit of an iteration process, which may converge to an equilibrium point, but limit cycles or chaotic behaviour may also show up. In this paper, we examine the existence and uniqueness of fixed points for two types of input-output fuzzy cognitive maps. Moreover, we use network-based measures like in-degree, out-degree and connectivity, to express conditions for the convergence of the iteration process.

Open Access: Yes

DOI: 10.1007/978-3-030-52705-1_33

Improvements on the Convergence and Stability of Fuzzy Grey Cognitive Maps

István Harmati L. T. Koczy

Publication Name: Communications in Computer and Information Science

Publication Date: 2020-01-01

Volume: 1239 CCIS

Issue: Unknown

Page Range: 509-523

Description:

Fuzzy grey cognitive maps (FGCMs) are extensions of fuzzy cognitive maps (FCMs), where the causal connections between the concepts are represented by so-called grey numbers. Just like in classical FCMs, the inference is determined by an iteration process, which may converge to an equilibrium point, but limit cycles or chaotic behaviour may also show up. In this paper, based on network measures like in-degree, out-degree and connectivity, we provide new sufficient conditions for the existence and uniqueness of fixed points for FGCMs. Moreover, a tighter convergence condition is presented using the spectral radius of the modified weight matrix.

Open Access: Yes

DOI: 10.1007/978-3-030-50153-2_38

On the Convergence of Sigmoidal Fuzzy Grey Cognitive Maps

István Harmati L. T. Koczy

Publication Name: International Journal of Applied Mathematics and Computer Science

Publication Date: 2019-09-01

Volume: 29

Issue: 3

Page Range: 453-466

Description:

Fuzzy cognitive maps (FCMs) are recurrent neural networks applied for modelling complex systems using weighted causal relations. In FCM-based decision-making, the inference about the modelled system is provided by the behaviour of an iteration. Fuzzy grey cognitive maps (FGCMs) are extensions of fuzzy cognitive maps, applying uncertain weights between the concepts. This uncertainty is expressed by the so-called grey numbers. Similarly as in FCMs, the inference is determined by an iteration process which may converge to an equilibrium point, but limit cycles or chaotic behaviour may also turn up. In this paper, based on the grey connections between the concepts and the parameters of the sigmoid threshold function, we give sufficient conditions for the existence and uniqueness of fixed points of sigmoid FGCMs.

Open Access: Yes

DOI: 10.2478/amcs-2019-0033

Notes on the Dynamics of Hyperbolic Tangent Fuzzy Cognitive Maps

István Harmati L. T. Koczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2019-06-01

Volume: 2019-June

Issue: Unknown

Page Range: Unknown

Description:

Fuzzy cognitive maps (FCMs) are recurrent neural networks applied for modelling complex systems and structures. In this method, the system is represented by a weighted, directed digraph, where the nodes of the network represent the main characteristics of the modelled system, while the weighted and directed edges correspond to the direction and strength of causal relationships between these factors. The FCM based decision making is based on the so-called activation values of the nodes, which represents the state of the system. These activation values are determined by an iteration, which may lead to an equilibrium point (fixed point), but limit cycles or chaotic behaviour may also occur. In this paper, the dynamics of fuzzy cognitive maps with hyperbolic tangent threshold function is mathematically discussed. Theoretical conditions are provided for the existence and uniqueness of fixed points. Moreover, the stability of fixed points and their basins of attractions are also analysed. The results presented here give insight into the special symmetric nature of hyperbolic FCMs.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2019.8858950

On the lower limit for possibilistic correlation coefficient with identical marginal possibility distributions

István Harmati Robert Fullér

Publication Name: Studies in Computational Intelligence

Publication Date: 2019-01-01

Volume: 794

Issue: Unknown

Page Range: 99-113

Description:

In 2011 Fullér et al. [An improved index of interactivity for fuzzy numbers, Fuzzy Sets and Systems, 165 (2011), pp. 50–60] introduced a new measure of interactivity between fuzzy numbers (interpreted as possibility distributions), called the weighted possibilistic correlation coefficient, which can be determined from their joint possibility distribution. They also left two questions open regarding the lower limit of the weighted possibilistic correlation coefficient of marginal possibility distribution with the same membership function. In this paper we will answer these questions not only in the case of fuzzy numbers, but also for quasi fuzzy numbers.

Open Access: Yes

DOI: 10.1007/978-3-030-01632-6_7

On possibilistic version of distance covariance and correlation

István Harmati Robert Fullér

Publication Name: Studies in Computational Intelligence

Publication Date: 2019-01-01

Volume: 796

Issue: Unknown

Page Range: 175-181

Description:

Distance correlation is a relatively new measure of dependence in probability theory and statistics, which has the great advantage that it gives zero if and only if the variables are independent. In this paper we define its possibilistic version. Namely, we equip each γ -level set of the joint possibility distribution with a uniform probability distribution, then we determine the probabilistic distance covariance and correlation between the marginal distributions. Finally, the possibilistic distance covariance and correlation is computed as the weighted average of these probabilistic measures of dependence.

Open Access: Yes

DOI: 10.1007/978-3-030-00485-9_20

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

István Harmati L. 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

On measures of dependence between possibility distributions

István Harmati P. Várlaki Robert Fullér

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2018-01-01

Volume: 15

Issue: 1

Page Range: 231-246

Description:

A measure of possibilistic correlation between marginal possibility distributions of a joint possibility distribution can be defined as (see Fullér, Mezei and Várlaki, An improved index of interactivity for fuzzy numbers, Fuzzy Sets and Systems, 165(2011), pp. 56-66) the weighted average of probabilistic correlations between marginal probability distributions whose joint probability distribution is defined to be uniform on the level sets of their joint possibility distribution. Using the averaging technique we shall discuss three quantities (correlation coefficient, correlation ratio and informational coefficient of correlation) which are used to measure the strength of dependence between two possibility distributions. We discuss the inverse problem, as we introduce a method to construct a joint possibility distribution for a given value of possibilistic correlation coefficient. We also discuss a special case when the joint possibility distribution is defined by the so-called weak t-norm and based on these results, we make a conjecture as an open problem for the range of the possibilistic correlation coefficient of any t-norm based joint distribution.

Open Access: Yes

DOI: 10.12700/APH.15.1.2018.1.14

On possibilistic dependencies: A short survey of recent developments

István Harmati Robert Fullér

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2018-01-01

Volume: 360

Issue: Unknown

Page Range: 261-273

Description:

Carlsson and Fullér introduced the notions of possibilistic mean value and variance of fuzzy numbers. Fullér and Majlender introduced a measure of possibilistic covariance between marginal distributions of a joint possibility distribution as the average value of the interactivity relation between the level sets of its marginal distributions. Fullér et al. introduced the possibilistic correlation ratio, the possibilistic correlation coefficient and the possibilistic informational coefficient of correlation. In this paper we give a short survey of some later works which extend and develop these notions.

Open Access: Yes

DOI: 10.1007/978-3-319-64286-4_16

On the existence and uniqueness of fixed points of fuzzy cognitive maps

F. Hatwágner István Harmati L. T. Koczy

Publication Name: Communications in Computer and Information Science

Publication Date: 2018-01-01

Volume: 853

Issue: Unknown

Page Range: 490-500

Description:

Fuzzy Cognitive Maps (FCMs) are decision support tools, which were introduced to model complex behavioral systems. The final conclusion (output of the system) relies on the assumption that the system reaches an equilibrium point (fixed point) after a certain number of iteration. It is not straightforward that the iteration leads to a fixed point, since limit cycles and chaotic behaviour may also occur. In this article, we give sufficient conditions for the existence and uniqueness of the fixed point for log-sigmoid and hyperbolic tangent FCMs, based on the weighted connections between the concepts and the parameter of the threshold function. Moreover, in a special case, when all of the weights are non-negative, we prove that fixed point always exists, regardless of the parameter of the threshold function.

Open Access: Yes

DOI: 10.1007/978-3-319-91473-2_42

Fuzzy signature based methods for modelling the structural condition of residential buildings

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2018-01-01

Volume: 357

Issue: Unknown

Page Range: 237-273

Description:

Conservation, extension or renovation of residential buildings is a task that requires intensive attention, where it must be ensured that design and construction works are carried out in proper quality. Priority is given to the proper use of the available financial resources. Incorrect assessment of renovation or reconstruction needs might cause considerable financial loss without implementing necessary interventions (which could eliminate eventual deteriorations, or hinder their reoccurrence).

Open Access: Yes

DOI: 10.1007/978-3-319-60207-3_16

M-estimators using optimization algorithm based on F-transform

Jin Hee Yoon Kisung Seo István Harmati Deokhwan Kyeong

Publication Name: Ifsa Scis 2017 Joint 17th World Congress of International Fuzzy Systems Association and 9th International Conference on Soft Computing and Intelligent Systems

Publication Date: 2017-08-30

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Robust estimation is an estimation technique which is insensitive to small departures from the idealized assumptions, especially inclusion of outliers of the data set. One of the popular robust technique is the so-called M-estimators. In a practical sense, there are many cases when the data set includes outliers, robust technique has been developed with various approaches due to its practical usefulness. In this paper, we propose a new algorithm based on F(Fuzzy)-transform and optimization algorithm, a modified GA (Genetic Algorithm). For this, two approaches are considered for comparison in order to minimize the objective functions of several robust M-estimators such as L1, L1 - L2 and Fair methods. One is a method which employs GA(Genetic Algorithm) as an optimization algorithm for minimization of the objective functions and the other one is a combined method based on F-transform and GA(Genetic Algorithm)which improves the accuracies. For a numerical example, the results are given with L2 (Least-squares) method, which is most popular but sensitive to outliers, for comparison. The performances are measured in RMSE, MAD and MAPE to show its superiority.

Open Access: Yes

DOI: 10.1109/IFSA-SCIS.2017.8023368

Modelling twofold uncertainty in the condition assessment of residential buildings using interval valued fuzzy signatures

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: 2016 IEEE Symposium Series on Computational Intelligence Ssci 2016

Publication Date: 2017-02-09

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

In this study we will describe an intervention decision-support method related to residential buildings, which is modelling the condition of buildings based on linguistic expert opinions so that it is capable of taking into consideration the uncertainties included in the expert opinions. Fuzzy signature-based model is used, wherein the uncertainties are integrated into the system by applying interval valued fuzzy sets, as well as linguistic hedges. The result will be a fuzzy set for each building, describing the condition of the whole building, specify the bourdary values between which the condition of the building may fall.

Open Access: Yes

DOI: 10.1109/SSCI.2016.7849994

On the sensitivity of type-2 fuzzy signatures and the generalizations of the extension principle

István Harmati L. T. Koczy

Publication Name: 2016 IEEE International Conference on Fuzzy Systems Fuzz IEEE 2016

Publication Date: 2016-11-07

Volume: Unknown

Issue: Unknown

Page Range: 1301-1307

Description:

When the exact mathematical model is not known or too difficult to handle, fuzzy signatures are useful tools in modeling and analysis of complex systems. In these cases the input values naturally have uncertainties, due to lack of knowledge or human activities. These built-in uncertainties influence the final decision about the system. In this paper we deal with the issue when the input parameters are not crisp values, but nonnegative fuzzy numbers, so we discuss the sensitivity of type-2 fuzzy signatures which are equipped with the weighted general mean as aggregation operator. The uncertainty of the result depends on the applied extension of real function to fuzzy numbers, so we discuss the case of Zadeh's extension principle, t-norm based extension and joint possibility distribution based extension of real functions, too.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2016.7737839

Integrated urban air pollution dispersion modelling framework and application in air quality prediction of the city of győr

É V.P. Rácz L. Környei Balázs Szintai István Harmati György Istenes Bence Liszkai Péter Zsebők Zoltán Horváth

Publication Name: Harmo 2016 17th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes Proceedings

Publication Date: 2016-01-01

Volume: 2016-May

Issue: Unknown

Page Range: 410-414

Description:

Model accuracy versus model running time - urban air pollution dispersion modellers have to balance between them when selecting models to be implemented. CFD based models seem to be the best candidates for an accurate model that can be validated at urban scale at highest level on the price of a longer running time. In this paper we shall introduce 3DAirQC software framework which addresses a portable and validated CFD model for air quality prediction and control.

Open Access: Yes

DOI: DOI not available

Minkowski's inequality based sensitivity analysis of fuzzy signatures

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: Journal of Artificial Intelligence and Soft Computing Research

Publication Date: 2016-01-01

Volume: 6

Issue: 4

Page Range: 219-229

Description:

Fuzzy signatures were introduced as special tools to describe and handle complex systems without their detailed mathematical models. The input parameters of these systems naturally have uncertainties, due to human activities or lack of precise data. These uncertainties influence the final conclusion or decision about the system. In this paper we discuss the sensitivity of the weigthed general mean aggregation operator to the uncertainty of the input values, then we analyse the sensitivity of fuzzy signatures equipped with these aggregation operators. Finally, we apply our results to a fuzzy signature used in civil enginnering.

Open Access: Yes

DOI: 10.1515/jaiscr-2016-0016

On the sensitivity of weighted general mean based type-2 fuzzy signatures

István Harmati L. T. Koczy

Publication Name: Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics

Publication Date: 2016-01-01

Volume: 9692

Issue: Unknown

Page Range: 206-218

Description:

Fuzzy signatures offer a possible way of describing, modeling and analysing of complex systems, when the exact mathematical model is not known or too difficult to handle. In these cases the input values have uncertainties, due to lack of knowledge or human activities. These uncertainties have influence on the final decision about the system. The uncertainties are taken into consideration as fuzzy sets, for example representing the uncertainty of a linguistic variable. In this paper we discuss the input sensitivity of type-2 weighted general mean aggregation operator and fuzzy signatures which are equipped with general means as aggregation operators.

Open Access: Yes

DOI: 10.1007/978-3-319-39378-0_19

On the sensitivity of the weighted relevance aggregation operator and its application to fuzzy signatures

István Harmati L. T. Koczy

Publication Name: Communications in Computer and Information Science

Publication Date: 2016-01-01

Volume: 611

Issue: Unknown

Page Range: 798-808

Description:

The weighted relevance aggregation operator is a modified, flexible version of the general power mean. In this paper we discuss the sensitivity of this operator, namely we give bounds on the change of the output in terms of vector norms of the change of the input variables. We apply these results to characterize to sensitivity of fuzzy signatures which are equipped with these operators in its nodes.

Open Access: Yes

DOI: 10.1007/978-3-319-40581-0_65

Three level modelling of uncertainties in the condition assessment of buildings

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: Isciia 2016 7th International Symposium on Computational Intelligence and Industrial Applications

Publication Date: 2016-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Condition survey evaluation analyses (enginering-static expert reports) are often prepared about building structures (often focusing on load-bearing structures) in order to support appropriate maintenance and repair of the existing buildings. Based on these analyses modelling of the condition of buildings and building structures can be a big help to adopt decisions on intervention. In the course of our former research condition evaluation, decision support and ranking method was worked out which, based on a unified system of viewpoints, considering various priorities, is able to determine the condition of residential buildings. We have used tree-structure, fuzzy singleton signature based model, in which the expert specifies one discrete value for the condition of every examined building structure. In the course of our research it was experienced that the elaborated method is too subjective and uncertain, therefore the method is being further developed so that modelling of objective and subjective uncertainties become possible in the course of preparing expert opinions. Three levels were created to model uncertainties. Uncertainty on level 1 is how to transform verbal evaluations into fuzzy membership functions (verbal values cannot be unambiguously transformed into numerical values). In this model instead of membership values, which were used in the former model, we assign linguistic label modelling membership functions to the leaves of the structure. Level 2 we are modelling an uncertainty where even the expert is unable to precisely determine the condition of the examined structure. Often an interval is specified for the condition of the structure instead of a specific status value. It means that the condition of structure can have any value between two specified values with the same probability. To model it the triangular-shaped membership function is transformed into a trapezoidal-shaped membership function with the help of linguistic hedges. On level 3 it is modelled that the expert evaluation itself is not considered totally reliable. Subjectivity, professional preparedness of the expert, conducting the examination, or the quality of available circumstances and data may significantly influence the reliability of the final result. These uncertainties can be modelled by modifying the shapes of the membership function. The fuzzy set signature based model created by modelling the uncertainties at three levels is able to model with proper accuracy (more sophistically as compared to the former model) the condition of buildings, which were specified by verbal evaluation in expert opinion.

Open Access: Yes

DOI: DOI not available

Sensitivity analysis of the weighted generalized mean aggregation operator and its application to fuzzy signatures

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2014-09-04

Volume: Unknown

Issue: Unknown

Page Range: 1327-1332

Description:

In this paper we give bounds on the changing of the weighted generalized mean in terms of vector norms of the changing of the variables. Applying this result we characterize the sensitivity of fuzzy signatures which equipped with weighted generalized mean operators in their nodes. Finally, a practical example from civil engineering is also examined.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2014.6891814

Sensitivity and validity of the fuzzy signature based evaluation of residential building conditions

Ádám Bukovics István Harmati L. T. Koczy

Publication Name: Civil Comp Proceedings

Publication Date: 2014-01-01

Volume: 105

Issue: Unknown

Page Range: Unknown

Description:

The characteristics and the status of the existing stock of residential buildings are extremely important for the national economy of all countries including Hungary. Formerly some methods and approaches to formally tackle and evaluate individual buildings based on available records and expert reports were formulated. These methods are suitable for the evaluation and ranking of residential buildings and make it easier to complete the status assessment and decision support for further utilization. A mathematical analysis has been conducted to identify the sensitivity of the calculated final results in the case of the applied fuzzy signatures related to the changes of the membership values at the leaves (the end nodes of a graph). This paper briefly presents the methods, then it investigates the validity of these results taking into consideration the possible subjective discrepancy and certainty in the evaluations.

Open Access: Yes

DOI: DOI not available

On weighted possibilistic informational coefficient of correlation

István Harmati P. Várlaki I. J. Rudas Robert Fullér

Publication Name: International Journal of Mathematical Models and Methods in Applied Sciences

Publication Date: 2012-12-19

Volume: 6

Issue: 4

Page Range: 592-599

Description:

In their previous works Fullér et al. introduced the notions of weighted possibilistic correlation coefficient and correlation ratio as measures of dependence between possibility distributions (fuzzy numbers). In this paper we introduce a new measure of strength of dependence between marginal possibility distributions, which is based on the informational coefficient of correlation. We will show some examples that demonstrate some good properties of the proposed measure.

Open Access: Yes

DOI: DOI not available

Searching for a nonlinear ODE model of vehicle crash with genetic optimization

F. Hatwágner István Harmati Andras Horvath

Publication Name: Saci 2012 7th IEEE International Symposium on Applied Computational Intelligence and Informatics Proceedings

Publication Date: 2012-01-01

Volume: Unknown

Issue: Unknown

Page Range: 131-136

Description:

Vehicle crash is a very complex process, which can be modelled in details using the finite element method (FEM), but a simple, quasi-heuristic model with a limited number of parameters is often more beneficial. In this paper we propose a relatively simple dynamic model for deformation and force during a frontal collision process, which has very similar behavior to the experimental data. A genetic-type optimization of model parameters is executed on three car crash experimental data sets. ©2012 IEEE.

Open Access: Yes

DOI: 10.1109/saci.2012.6249990

Probabilistic correlation coefficients for possibility distributions

István Harmati P. Várlaki Robert Fullér

Publication Name: Ines 2011 15th International Conference on Intelligent Engineering Systems Proceedings

Publication Date: 2011-08-22

Volume: Unknown

Issue: Unknown

Page Range: 153-158

Description:

The goal of this paper to introduce two alternative definitions for the possibilistic correlation coefficient by equipping the level sets of a joint possibility distribution with nonuniform probability distributions which are directly derived from the shape function of the joint possibility distribution. We also show some examples for their exact calculation for joint possibility distributions defined by Mamdani, Łukasiewicz and Larsen triangular norms. © 2011 IEEE.

Open Access: Yes

DOI: 10.1109/INES.2011.5954737

On possibilistic correlation coefficient and ratio for fuzzy numbers

József Mezei István Harmati P. Várlaki Robert Fullér

Publication Name: Recent Researches in Artificial Intelligence Knowledge Engineering and Data Bases 10th Wseas International Conference on Artificial Intelligence Knowledge Engineering and Data Bases Aiked 11

Publication Date: 2011-06-17

Volume: Unknown

Issue: Unknown

Page Range: 263-268

Description:

In this paper we show some properties of possibilistic correlation coefficient and correlation ratio for marginal possibility distributions. We will show some examples for their computation from some joint possibility distributions.

Open Access: Yes

DOI: DOI not available

A note on f-weighted possibilistic correlation for identical marginal possibility distributions

István Harmati

Publication Name: Fuzzy Sets and Systems

Publication Date: 2011-02-16

Volume: 165

Issue: 1

Page Range: 106-110

Description:

Fullér, Mezei and Várlaki defined the f-weighted possibilistic correlation coefficient as a new measure of interactivity of fuzzy numbers, which can be determined from the joint possibility distribution. At the end of their paper they formulated problems in connection with the lower limit of the f-weighted possibilistic correlation coefficient, if we know only the marginal distributions. In this paper we will discuss these problems. © 2010 Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.fss.2010.11.005

On possibilistic correlation coefficient and ratio for triangular fuzzy numbers with multiplicative joint distribution

István Harmati P. Várlaki Robert Fullér

Publication Name: 11th IEEE International Symposium on Computational Intelligence and Informatics Cinti 2010 Proceedings

Publication Date: 2010-12-01

Volume: Unknown

Issue: Unknown

Page Range: 103-108

Description:

The goal of this paper is to provide calculation formulas for the possibilistic correlation coefficient and ratio for two marginal possibility distributions of triangular form when their joint possibility distribution is defined by the product t-norm. We will also introduce an alternative definition for the possibilistic correlation coefficient and ratio when their joint possibility distribution is defined by the product t-norm. ©2010 IEEE.

Open Access: Yes

DOI: 10.1109/CINTI.2010.5672266

Application of LPV type force model in vehicle crash dynamics

István Harmati András Rövid P. Várlaki

Publication Name: Proceedings of the 9th Wseas International Conference on Applications of Computer Engineering Ace 10

Publication Date: 2010-12-01

Volume: Unknown

Issue: Unknown

Page Range: 174-179

Description:

In the research field of vehicle crash mechanics one of the most important task is finding a model for the deformational force, which gives acceptable approximation, but doesn't need perfect knowledge about the parameters of the vehicle. The FEM based methods, which are applied in the engineering practice give good approximations, but they have extremely large computational complexity and need a large amount of data. On the other hand there exist simple force models, but they not approximate well in details the force-deflection curve. In this paper we introduce a force model for vehicle deformation based on the LPV-HOSVD paradigm, which well approximates the force during the deformational process and has acceptable complexity.

Open Access: Yes

DOI: DOI not available

Approximation of force and energy in vehicle crash using LPV type description

István Harmati András Rövid P. Várlaki

Publication Name: Wseas Transactions on Systems

Publication Date: 2010-07-01

Volume: 9

Issue: 7

Page Range: 734-743

Description:

In accident analysis, vehicle crash mechanics and vehicle safety research modeling of the deformational force and absorbed energy plays a crucial role. The usually applied FEM based methods give good approximations, but they have extremely large computational complexity and require a detailed knowledge about the parameteres of the crash and the vehicle. There are simpler models, but they not give satisfactory approximation. In this paper using the LPV-HOSVD paradigm we introduce a model for vehicle deformation process, which well approximates the deformation force and the absorbed energy, moreover it has acceptable computational complexity.

Open Access: Yes

DOI: DOI not available

LPV type model of deformational force in vehicle collisions

István Harmati András Rövid P. Várlaki

Publication Name: Iccc 2009 IEEE 7th International Conference on Computational Cybernetics

Publication Date: 2009-12-01

Volume: Unknown

Issue: Unknown

Page Range: 103-108

Description:

Modeling of the deformational force and absorbed energy plays a very important role in different fields of vehicle engineering. The usually applied FEM based methods give good approximations, but they have extremely large computational complexity. On the other hand there exist simple force models, but they not approximate well in details the real data. The aim of this paper is to introduce a force model for vehicle deformation, which is able to describe the real process and have acceptable complexity. ©2009IEEE.

Open Access: Yes

DOI: 10.1109/ICCCYB.2009.5393952

Half-magnitude extensions of resolution and field of view in digital holography by scanning and magnification

A. Lotfi Attila Tibor Nagy István Harmati Béla Ráczkevi György Molnar Dezsö Szigethy Attila Nagy G. Molnárka Venczel Borbély Ferenc Gyímesi Aladar Czitrovszky Zoltán Füzessy

Publication Name: Applied Optics

Publication Date: 2009-11-01

Volume: 48

Issue: 31

Page Range: 6026-6034

Description:

Digital holography replaces the permanent recording material of analog holography with an electronic light sensitive matrix detector, but besides the many unique advantages, this brings serious limitations with it as well. The limited resolution of matrix detectors restricts the field of view, and their limited size restricts the resolution in the reconstructed holographic image. Scanning the larger aerial hologram (the interference light field of the object and reference waves in the hologram plane) with the small matrix detector or using magnification for the coarse matrix detector at the readout of the fine-structured aerial hologram, these are straightforward solutions but have been exploited only partially until now. We have systematically applied both of these approaches and have driven them to their present extremes, over half a magnitude in extensions. © 2009 Optical Society of America.

Open Access: Yes

DOI: 10.1364/AO.48.006026

Energy distribution modeling of car body deformation using LPV representations and fuzzy reasoning

István Harmati András Rövid P. Várlaki László Szeidl

Publication Name: Wseas Transactions on Systems

Publication Date: 2008-12-01

Volume: 7

Issue: 11

Page Range: 1228-1237

Description:

The main aim of the paper is to introduce a novel method - based on fuzzy control and linear parameter varying (LPV) system representation transformable into HOSVD based Canonical form - for modeling deformation processes with respect to the distribution of the absorbed kinetic energy. Modeling such kind of processes requires many uncertain input parameters. Using the proposed concept we are able to handle them and keep the complexity of the models low by using higher order singular value decomposition (HOSVD) technique.

Open Access: Yes

DOI: DOI not available

Energy absorption modelling technique for car body deformation

István Harmati András Rövid P. Várlaki

Publication Name: Saci 2007 4th International Symposium on Applied Computational Intelligence and Informatics Proceedings

Publication Date: 2007-10-01

Volume: Unknown

Issue: Unknown

Page Range: 269-272

Description:

The main object of this paper is to introduce a model for describing how the enrgy distribution changes during deformational processes, esp. in car crashes. This an important and difficult task in accident analysis and in safety car-body design. Exact estimation or measuring of the absorbed energy by the deformation is almost impossible. The classical tool for this task is usually a differental equation based finite element method, which requires exact knowledge about the parameters and takes a lot of computational time with high complexity. In the following we introduce a simple numerical model for the changing of the energy distribution during the whole deformational process. © 2007 IEEE.

Open Access: Yes

DOI: 10.1109/SACI.2007.375523

Estimation of energy distribution for car-body deformation

István Harmati P. Várlaki

Publication Name: Isciii 07 3rd International Symposium on Computational Intelligence and Intelligent Informatics Proceedings

Publication Date: 2007-01-01

Volume: Unknown

Issue: Unknown

Page Range: 229-232

Description:

Identification of distribution of deformational energy for vehicle body deformational processes is a very important and difficult task in accident analysis and in safety car-body design. Exact estimation or measuring of the absorbed energy by the deformation is almost impossible, so we apply an estimation for this. The classical tool for this task is usually a differental equation based finite element method, which requires exact knowledge about the parameters. In the following we introduce a simple numerical model describing the changing of the energy distribution during the whole deformational process. The main idea is similar to a finite element method: let have a 3D rectangular grid on the car-body, according to the energy absorbing properties of the vehicle, so each cell is approximately homogenous. For For each cell a monotonous decreasing function is assigned, which describes approximately the rate of the absorbed and the input energy. For different possible directions of the impact we define different absorbing functions, and instead of the original input, we deal with its orthogonal components, so the final result then will be the sum of the particular result. © 2007 IEEE.

Open Access: Yes

DOI: 10.1109/ISCIII.2007.367394

Takagi-sugeno fuzzy control models for large scale logistics systems

Gabriella Orbán István Harmati P. Várlaki

Publication Name: Isciii 07 3rd International Symposium on Computational Intelligence and Intelligent Informatics Proceedings

Publication Date: 2007-01-01

Volume: Unknown

Issue: Unknown

Page Range: 199-203

Description:

Requirements, such as adaptive behavior, learning ability and self regulative features, that have to be met by modern logistic systems, need the construction of such control systems that are able to control the basic processes and also to develop and improve the material and information system by automating the control processes. For controlling the logistical systems the papers propose the application of LPV structure by which non-linear systems can be controlled on the basis of linear control theories. The proposal points out that the priorities of different states are of great importance when generating the logical rules of operation. For resolving the difficulties of constructing mathematical algorithms fuzzy sets are suggested, so in the control model a Takagi-Sugeno solution is proposed, that can describe multi-input multi-output, non-linear, dynamic systems like logistical systems. © 2007 IEEE.

Open Access: Yes

DOI: 10.1109/ISCIII.2007.367389

Identification and reconstruction of car body deformation applying tensor product models

István Harmati András Rövid P. Várlaki László Szeidl

Publication Name: Ines 2006 10th International Conference on Intelligent Engineering Systems 2006

Publication Date: 2006-12-01

Volume: Unknown

Issue: Unknown

Page Range: 98-101

Description:

Car body deformation modeling plays a very important role in crash accident analyses, as well as in safe car body design. The determination of the energy absorbed by the deformation and the corresponding Energy Equivalent Speed can be of key importance, however their precise determination is a very difficult task. Although, using the results of crash tests, intelligent and soft methods offer an automatic way to model the crash process itself, as well as to determine the absorbed energy, the before-crash speed of the car, etc. In this paper a modeling technique and an intelligent expert system are introduced which together are able to follow the deformation process of car bodies in car crashes and to analyze the strength of the different parts without any human intervention thus significantly can contribute to the improvement of the modeling, (automatic) design, and safety of car bodies. © 2006 IEEE.

Open Access: Yes

DOI: DOI not available