Szilvia Nagy

7102596065

Publications - 77

A Systematic Analysis of Neural Networks, Fuzzy Logic and Genetic Algorithms in Tumor Classification

Ferenc Lilik Ahmed Al-Ashoor Szilvia Nagy

Publication Name: Applied Sciences Switzerland

Publication Date: 2025-05-01

Volume: 15

Issue: 9

Page Range: Unknown

Description:

This study explores existing research on neural networks, fuzzy logic-based models, and genetic algorithms applied to brain tumor classification. A systematic review of 53 studies was conducted following PRISMA guidelines, covering search strategy, selection criteria, quality assessment, and data extraction. Articles were collected from three scientific databases: Web of Science, Scopus, and IEEE. The review primarily focuses on practical contributions, with most studies emphasizing applications over conceptual insights. Key methods in the field demonstrate significant impact and innovation. Commonly used training and testing mechanisms include dataset splitting, augmentation, and validation techniques, highlighting their widespread adoption for performance evaluation. The analysis of evaluation metrics shows that accuracy and the DICE score are the most frequently used, alongside sensitivity, specificity, recall, and other domain-specific measures. The variety of metrics underscores the need for tailored approaches based on dataset characteristics and research objectives. By highlighting trends, challenges, and research gaps, this review provides actionable insights for advancing BTC research. It offers a comprehensive overview of techniques and evaluation methods to guide future developments in this critical domain.

Open Access: Yes

DOI: 10.3390/app15095186

Heartbeat Estimation from Subtle Body Vibrations via Inertial Sensing

Patrik Gabor Rozsa Szilvia Nagy

Publication Name: 60th International Scientific Conference on Information Communication and Energy Systems and Technologies Icest 2025 Proceedings

Publication Date: 2025-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

This paper presents a cost-conscious signal processing pipeline for detecting heartbeats from faint body vibrations using a single back-mounted inertial measurement unit (IMU). The system operates without ECG or PPG sensors, relying solely on accelerometer and gyroscope data. The pipeline is designed with the intent to run on lightweight edge-computing platforms, such as Raspberry Pi-class devices or even on a ESP32, while prioritizing energy efficiency and user-friendliness for extended battery-powered use. Preliminary validation against manually recorded heart rates demonstrates feasibility with limitations.

Open Access: Yes

DOI: 10.1109/ICEST66328.2025.11098443

Liver Cancer Classification Approach Using Yolov8

Belal Al-Khateeb Fatimah Ihsan Abdulsahib L. T. Koczy Szilvia Nagy

Publication Name: Lecture Notes in Networks and Systems

Publication Date: 2025-01-01

Volume: 1176 LNNS

Issue: Unknown

Page Range: 14-21

Description:

Liver cancer is a common and often fatal disorder that is becoming more commonplace worldwide. An accurate and timely diagnosis is necessary for both effective treatment and patient survival. In machine learning techniques, particularly deep learning, obtaining a large and diverse dataset is still a challenge for deep neural network training, particularly in the medical industry. This paper presents a classification of circulating tumor cells based on the YOLOv8 algorithm. Tumor cell identification and classification can be achieved by utilizing the algorithm’s multi-layer high-level stacking, weight sharing, local connection, and pooling characteristics. The goal is to design a liver cancer classification system that makes it easier and increases the efficiency of doctors in analyzing the results of liver cancer. The models show the absolute the accuracy is 100%, 100%, 98%, 96% to Yolov8n, Yolov8s, Yolov8m, and Yolov8l respectively.

Open Access: Yes

DOI: 10.1007/978-3-031-73997-2_2

Macrogeometric Measurement of Camshafts of Internal Combustion Engines

Levente Solecki Szilvia Nagy

Publication Name: Strojnicky Casopis

Publication Date: 2024-11-01

Volume: 74

Issue: 2

Page Range: 71-82

Description:

In this work, cam profiles of a camshaft are measured by a roundness measurement machine. First, the measured cam profiles are transformed into their actual sizes, based on the measurement of the bearing locations. The 8 cams of the camshaft are of two types. From the 4-4 cam profiles of each type an approximate profile is created by fitting them to one another using their base circles as reference, and calculating the center of gravity of the cumulative points of these fitted profiles corresponding to an arc segment.

Open Access: Yes

DOI: 10.2478/scjme-2024-0028

Adjacent-Channel Compatibility Analysis of International Mobile Telecommunications Downlink and Digital Terrestrial Television Broadcasting Reception in the 470–694 MHz Frequency Band Using Monte Carlo Simulation

Péter Vári Hussein Taha Szilvia Nagy

Publication Name: Electronics Switzerland

Publication Date: 2024-02-01

Volume: 13

Issue: 3

Page Range: Unknown

Description:

This paper delves into the imperative need for coexistence and compatibility in the 470–694 MHz frequency band, as mandated by the World Radiocommunication Conference 2015 (WRC-15) and the WRC-23. It focuses on challenges in the coexistence of Digital Terrestrial Television Broadcasting (DTTB) and International Mobile Telecommunications-2020 (IMT-2020) services in downlink-only mode, particularly in adjacent-channel scenarios. Using Monte Carlo simulations, the study evaluates the probability of interference from IMT base stations with DTTB reception. The analysis thoroughly investigates the impact of the IMT transmitter’s Adjacent Channel Leakage Ratio (ACLR) and the DTTB receiver’s Adjacent-Channel Selectivity (ACS) on the probability of interference. The results demonstrate a significant degradation in the DTTB reception probability at the edge of coverage based on standard assumptions. To address these challenges, this paper provides recommendations for mitigating interference. These include defining enhanced ACLR regulations for IMT base stations, implementing antenna discriminations, providing specialized filters, and establishing national coordination procedures. The research provides valuable insights for informed decision making in spectrum management within the 470–694 MHz band, aiming to facilitate the coexistence of DTTB and IMT-2020 services, in line with international regulations and best practices.

Open Access: Yes

DOI: 10.3390/electronics13030575

Optimizing the geometry of a cylindrical dielectric resonator antenna (CDRA) in combination with the design of a microstrip patch antenna to improve antenna efficiency

Hussein Turki Alateewe Szilvia Nagy

Publication Name: Periodicals of Engineering and Natural Sciences

Publication Date: 2024-01-01

Volume: 12

Issue: 1

Page Range: 5-18

Description:

The primary objective of this study is to improve the efficiency of dielectric resonator antennas (DRAs) by the manipulation of their geometric and material characteristics. Two distinct cylindrical dielectric resonator antenna (DRA) with microstrip patch antenna designs chosen, and deliberate modifications implemented in a systematic manner to enhance crucial characteristics including gain, bandwidth, S-parameters, voltage standing wave ratio (VSWR), and directivity. Furthermore, an investigation was conducted to assess the efficacy of incorporating additional layers into the design of the DRA to achieve increased gain and enhanced efficiency at a frequency of 28 GHz. The research encompassed the process of collecting and designing and simulating CDRA and microstrip patch antenna antennas utilizing the CST framework. The study investigates different configurations of apertures and alterations or holes in the patch geometry to improve both the gain and efficiency. A comparative analysis between both antennas was carried out utilizing performance criteria such as S-parameters, gain, directivity, bandwidth, and VSWR and efficiency. The discourse explores the progress made in the field of technology pertaining to the improvement of gain and bandwidth. This includes the utilization of high-dielectric-constant materials, modifications in resonant frequencies, and the implementation of metamaterial (MTM) cells. The CST program is utilized for conducting realistic trials and assessments. The research highlights the advantages of CDRA antennas and microstrip patch antennas, including improved radiation efficiency, smaller size, lower profile, and lightweight design. The integration of photonic crystal layers into the design of the cylindrical dielectric resonator antenna (CDRA) was emphasized as a noteworthy enhancement, resulting in amplified gain. The significance of considering both intrinsic characteristics and external factors, such as surface Plasmon waves, in the computational modeling of DRA antennas to achieve maximum efficiency is emphasized by the research.

Open Access: Yes

DOI: 10.21533/pen.v12i1.3934.g1351

Co-Channel Compatibility Analysis of IMT Networks and Digital Terrestrial Television Broadcasting in the Frequency Range 470-694 MHz Based on Monte Carlo Simulation

Péter Vári Hussein Taha Szilvia Nagy

Publication Name: Sensors Basel Switzerland

Publication Date: 2023-10-25

Volume: 23

Issue: 21

Page Range: Unknown

Description:

According to Resolution 235 adopted during the World Radiocommunication Conference 2015 (WRC-15) and the preliminary agenda item 1.5 of WRC-2023, the International Telecommunication Union Radiocommunication Sector (ITU-R) has been entrusted to carry out sharing and compatibility studies between broadcasting and mobile services in the frequency range 470-694 MHz in Region 1. This study specifically focuses on evaluating electromagnetic compatibility in potential co-channel sharing scenarios between Digital Terrestrial Television Broadcasting (DTTB) and International Mobile Telecommunications (IMT) systems within the 470-694 MHz frequency band that may arise in the foreseeable future. To assess the conditions for coexistence, a Monte Carlo simulation method implemented through the SEAMCAT software version 5.4.2 is employed, examining six potential interference scenarios. The simulation results yield the minimum coordination distance required between IMT and DTTB services in the 470-694 MHz band based on the protection criteria to ensure harmonious coexistence while maintaining satisfactory performance. Furthermore, the study investigates the impact of various factors such as transmitter power, antenna heights, coverage radius, antenna discrimination, and antenna tilt angle on the separation distances. The focus lies primarily on critical interference scenarios across neighboring countries' borders. The simulation outcomes confirm that sharing the same frequency band between IMT and DTTB networks would result in significant mutual interference. Nevertheless, carefully analyzing diverse parameters and assumptions helped provide recommendations to reduce the required separation distances. These findings are valuable for broadcasters, mobile operators, and regulators in establishing the technical coexistence conditions for DTTB and IMT in the new band.

Open Access: Yes

DOI: 10.3390/s23218714

A Novel Gradient-Weighted Voting Approach for Classical and Fuzzy Circular Hough Transforms and Their Application in Medical Image Analysis—Case Study: Colonoscopy

Raneem Ismail Szilvia Nagy

Publication Name: Applied Sciences Switzerland

Publication Date: 2023-08-01

Volume: 13

Issue: 16

Page Range: Unknown

Description:

Featured Application: The circular fuzzy Hough transform with gradient-weighted voting can be used for finding the contours of circle-like shapes, such as colorectal polyps on colonoscopy images, as well as other cases that require a given relative gradient edge around the circle-like objects. Classical circular Hough transform was proven to be effective for some types of colorectal polyps. However, the polyps are very rarely perfectly circular, so some tolerance is needed, that can be ensured by applying fuzzy Hough transform instead of the classical one. In addition, the edge detection method, which is used as a preprocessing step of the Hough transforms, was changed from the generally used Canny method to Prewitt that detects fewer edge points outside of the polyp contours and also a smaller number of points to be transformed based on statistical data from three colonoscopy databases. According to the statistical study we performed, in the colonoscopy images the polyp contours usually belong to gradient domain of neither too large, nor too small gradients, though they can also have stronger or weaker segments. In order to prioritize the gradient domain typical for the polyps, a relative gradient-based thresholding as well as a gradient-weighted voting was introduced in this paper. For evaluating the improvement of the shape deviation tolerance of the classical and fuzzy Hough transforms, the maximum radial displacement and the average radius were used to characterize the roundness of the objects to be detected. The gradient thresholding proved to decrease the calculation time to less than 50% of the full Hough transforms, and the number of the resulting circles outside the polyp’s environment also decreased, especially for low resolution images.

Open Access: Yes

DOI: 10.3390/app13169066

On Selecting, Ranking, and Quantifying Features for Building a Liver CT Diagnosis Aiding Computational Intelligence Method

Ferenc Lilik Melinda Kovacs Szilvia Nagy

Publication Name: Applied Sciences Switzerland

Publication Date: 2023-03-01

Volume: 13

Issue: 6

Page Range: Unknown

Description:

Featured Application: The selected attributes and their ranking and weights can be used in decision support algorithms in computer aided diagnosis. The liver is one of the most common locations for incidental findings during abdominal CT scans. There are multiple types of disease that can arise within the liver and many of them are nodular. The ultimate goal of our research is to develop an expert knowledge-based system using fuzzy signatures, to support decisions during diagnosis of the most frequent of these nodular lesions. Since the literature contains limited information about the graphical properties of CT images that must be taken into consideration and their relationship to one another, in this paper we focused on selecting and ranking the input parameters using expert knowledge and determining their importance. Six visual attributes of lesions (size, shape, density, homogeneity contour, and other features) were selected based on textbooks of radiology and expert opinion. The importance of these attributes was ranked by radiologist experts using questionnaires and a pairwise comparison technique. The most important feature was found to be the density of the lesion on the various CT phases, and the least important was the size, the order of the other attributes was other features, contour, homogeneity, and shape, with a Kendall concordance coefficient of 0.612. Weights for the attributes, to be used in the future fuzzy signatures, were also determined. As a last step, several statistical parameter-based quantities were generated to represent the above abstract attributes and evaluated by comparing them to expert opinions.

Open Access: Yes

DOI: 10.3390/app13063462

On Applying Expert Knowledge for Spline-Based Segmentation of Liver on Computed Tomography Images

Melinda Kovacs Patrik Gabor Rozsa Szilvia Nagy

Publication Name: 2023 58th International Scientific Conference on Information Communication and Energy Systems and Technologies Icest 2023 Proceedings

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 21-24

Description:

The segmentation of the liver from the surrounding soft tissues between the ribs on a non-enhanced, arterial or delayed phase computed tomography image complicated, as the muscle and many other soft tissues have very similar X-ray attenuation to the liver, thus they manifest as similar intensity and similar pattern domains on the computed tomography images. However, if the anatomical setup of the human body and the location of the bones, that have much higher attenuation are taken into account, a sufficiently smooth and precise borderline can be drawn between the ribcage and the liver, that can be developed into a liver contour by successive erosion and active contour methods.

Open Access: Yes

DOI: 10.1109/ICEST58410.2023.10187395

Analysis of the WRC-23 Agenda Item Concerning the Future Use of the 470-694 MHz Band in Europe

Péter Vári Hussein Taha Szilvia Nagy

Publication Name: Infocommunications Journal

Publication Date: 2023-01-01

Volume: 15

Issue: 3

Page Range: 2-10

Description:

The upcoming World Radiocommunication Conference 2023 (WRC-23), according to the preliminary agenda item 1.5, will decide the long-term use of the 470-694 MHz band in International Telecommunication Union Region 1 and consider regulatory actions for the rest of the decade. This article attempts to inform the debate on the future use of spectrum in the 470- 694 MHz band and the status of broadcasting services at the European level and in many individual member states. This article highlights the role WRCs played by allocation of the previous digital dividend bands for mobile services. It provides an overview of the most recent trends and developments of existing services in the sub-700 MHz band. The article also explores and analyzes options for future use of the 470-694 MHz band in Europe and discusses the benefits and implications of adopting each option. Based on this analysis, it is recommended to introduce a secondary allocation to mobile service in the downlink-only mode alongside traditional broadcasting services in the sub-700 MHz band at the upcoming WRC-23.

Open Access: Yes

DOI: 10.36244/ICJ.2023.3.1

On the Applicability of Fuzzy Lines in Circular Hough Transform in Lesion Segmentation on Liver CT Images

Melinda Kovacs Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2023-01-01

Volume: 1040

Issue: Unknown

Page Range: 45-54

Description:

Most of the lesions that grow in the liver and need to be found on a CT take are roundish, though especially in the case of malignant lesions the irregularity of the shape is also rather common. Classical Hough transform, however, which is one of the most used methods for finding circles, usually fails to find the contours of these objects, because of the larger or smaller irregularity of the shapes. Introducing a fuzzification in the edge filtered version of the image, which is usually the basis of a Hough transform, makes the Hough transform more flexible for using in liver CT image analysis.

Open Access: Yes

DOI: 10.1007/978-3-031-07707-4_6

On Applying Gradient Based Thresholding on the Canny Edge Detection Results to Improve the Effectiveness of Fuzzy Hough Transform for Colonoscopy Polyp Detection Purposes

Péter Prukner Raneem Ismail Szilvia Nagy

Publication Name: Smart Innovation Systems and Technologies

Publication Date: 2023-01-01

Volume: 332 SIST

Issue: Unknown

Page Range: 110-121

Description:

The possibilities of improving the effectiveness of fuzzy Hough transform calculations in the detection of colonoscopy image processing and polyp detection by gradient based preprocessing is studied. For the Hough transforms a black and white image consisting of line segments is necessary, thus most of the times an edge detected image is used as the basis of the transform. Here, the gradient magnitude values corresponding to the Canny edge pixels of the image are used for determining, which are the typical magnitude values for the polyp contours, in order to remove part of the non-contour edges from the image. Three publicly available databases with images and ground truth masks are used for testing, whether a general threshold for the gradients is applicable, but based on the histograms it seems to be not possible to generate a database independent normalized gradient based domain that can be used for sorting out the unnecessary edges.

Open Access: Yes

DOI: 10.1007/978-981-19-7842-5_10

On Enhancement of Efficiency of Three Kinds of Rectangular DRA Antennas by Optimizing Geometrical Properties

Hussein Turki Alateewe Szilvia Nagy

Publication Name: 2023 58th International Scientific Conference on Information Communication and Energy Systems and Technologies Icest 2023 Proceedings

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 65-68

Description:

DRA antennas have several favorable characteristics such as small size, low cost and desirable radiation pattern. These advantages make companies use this antenna in different fields in communication. Our aim is to enhance some properties of the rectangular antenna such as gain, bandwidth, S-parameter, VSWR and directivity. Therefore, three kinds of rectangular DRA antenna designs were selected and their geometrical and material parameters were systematically changed to enhance their performance. Also, the effect of adding more layers into the DRA design to get higher gain and to enhance the efficiency at frequency 28 GHz was studied. The designing and simulating of the DRA antenna were carried out by using the framework of CST.

Open Access: Yes

DOI: 10.1109/ICEST58410.2023.10187334

On the aggregation functions used in fuzzy signatures based medical image analysis

Ferenc Lilik Melinda Kovacs L. T. Koczy Szilvia Nagy

Publication Name: IEEE 23rd International Symposium on Computational Intelligence and Informatics Cinti 2023 Proceedings

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 409-414

Description:

The paper proposes the use of fuzzy signatures for modeling and analysis of pre-processed medical images, as an example, CT images of the liver are analyzed. Fuzzy signatures are used for the case of distinguishing larger and smaller malignant lesions from each other and from other (benign) nodular diseases in liver computed tomography images. As computed tomography phases are sometimes missing, the treatment of missing data is also briefly addressed. As the size of the malignant lesion influences its manifestation on the images, separate sub-signatures are developed for large and small lesions with the size being a separate layer of the signature. From the medical experts' point of view besides the tree structure of the signature it is crutial to determine the aggregations themselves, which model the ways experts fuse and combine the available information. For the subtrees for small and large lesions in the sub-roots algebraic multiplication seems to be the best fitting t-norm, while in the subtree weighted means.

Open Access: Yes

DOI: 10.1109/CINTI59972.2023.10381986

A transfer learning approach for the classification of liver cancer

Belal Al-Khateeb Fatimah Ihsan Abdulsahib L. T. Koczy Szilvia Nagy

Publication Name: Journal of Intelligent Systems

Publication Date: 2023-01-01

Volume: 32

Issue: 1

Page Range: Unknown

Description:

Problem: The frequency of liver cancer is rising worldwide, and it is a common, deadly condition. For successful treatment and patient survival, early and precise diagnosis is essential. The automated classification of liver cancer using medical imaging data has shown potential outcome when employing machine and deep learning (DL) approaches. To train deep neural networks, it is still quite difficult to obtain a large and diverse dataset, especially in the medical field. Aim: This article classifies liver tumors and identifies whether they are malignant, benign tumor, or normal liver. Methods: This study mainly focuses on computed tomography scans from the Radiology Institute in Baghdad Medical City, Iraq, and provides a novel transfer learning (TL) approach for the categorization of liver cancer using medical images. Our findings show that the TL-based model performs better at classifying data, as in our method, high-level characteristics from liver images are extracted using pre-trained convolutional neural networks compared to conventional techniques and DL models that do not use TL. Results: The proposed method using models of TL technology (VGG-16, ResNet-50, and MobileNetV2) successfully achieves high accuracy, sensitivity, and specificity in identifying liver cancer, making it an important tool for radiologists and other healthcare professionals. The experiment results show that the diagnostic accuracy in the VGG-16 model is up to 99%, ResNet-50 model 100%, and 99% total classification accuracy was attained with the MobileNetV2 model. Conclusion: This proves the improvement of models when working on a small dataset. The use of new layers also showed an improvement in the performance of the classifiers, which accelerated the process.

Open Access: Yes

DOI: 10.1515/jisys-2023-0119

On the Challenges of Mutual Interference between Cable Television Networks and Mobile Fixed Communication Networks in the Digital Dividend Bands

Péter Vári Hussein Taha Szilvia Nagy

Publication Name: Infocommunications Journal

Publication Date: 2022-09-01

Volume: 14

Issue: 3

Page Range: 63-71

Description:

Recently, the issue of monitoring and repairing leakage from cable television networks have re-emerged, particularly after the International Telecommunication Union released a part of the ultra-high frequency spectrum to mobile broadband services. The newly allocated spectrum, known as the digital dividend bands, was traditionally used throughout Europe for digital TV broadcasting. The emerging problem is the mutual interference between the new frequency spectrum utilized by the Mobile/Fixed Communication Networks and the band used by cable TV providers to offer their services. This article is a brief overview and a starting point for extensive research in this area. We started with a simple description of the cable television system and mobile/fixed communication networks focusing on the aspects associated with ingress and egress interference issues. We also discussed the approaches for detecting and measuring mutual interference and reviewed the relevant literature. This article is concluded with some proposed measures for reducing or mitigating mutual interference.

Open Access: Yes

DOI: 10.36244/ICJ.2022.3.8

WAYS OF IMPROVING OF ACTIVE CONTOUR METHODS IN COLON-OSCOPY IMAGE SEGMENTATION

Raneem Ismail Szilvia Nagy

Publication Name: Image Analysis and Stereology

Publication Date: 2022-01-01

Volume: 41

Issue: 1

Page Range: 7-23

Description:

As colonoscopy is the standard screening approach for colorectal polyps, and the first step of the correct classification and the efficient automatic diagnostics is the accurate detection and segmentation of the ex-isting polyps, it is worth researching systematically, how colonoscopy databases are responding to two of the most influential variational segmentation methods, the geodesic and Chan–Vese active contour meth-ods. Due to the quality variation of the colonoscopy databases, pre-processing steps are made. Then, 14 various filtered images are evaluated as different inputs for the active contour methods using the Sørensen–Dice Similarity Coefficient as a performance measurement metric. The effects of the initial mask shape and its size together with the number of iterations, contraction bias and smoothness factor are studied. In gen-eral, the Chan–Vese method showed more efficiency to match the actual contour of the polyp than the geodesic one with an initial mask possibly located within the polyp area. Preprocessing such as reflection removal, background subtraction and mean or median filtering can improve the Sørensen–Dice coefficient by up to 0.5

Open Access: Yes

DOI: 10.5566/ias.2604

The effect of different consequent setting on the effectiveness of Kóczy-Hirota fuzzy rule interpolation in colonoscopy image classification

Brigita Sziová Raneem Ismail Hussein Taha Szilvia Nagy

Publication Name: 2022 57th International Scientific Conference on Information Communication and Energy Systems and Technologies Icest 2022

Publication Date: 2022-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The effect of the refinement of the consequent categories in Kï¿czy-Hirota fuzzy rule interpolation is studied in the model system of colonoscopy image classification. The colonoscopy image segments are classified based on 99 antecedents, which are statistical parameters of the image segments. The number of consequents is increased from 2 - contains polyp, or does not contain polyp - to a more refined set distribution based on the polyp content of the image segment.

Open Access: Yes

DOI: 10.1109/ICEST55168.2022.9828693

On using fuzzy c-means clustering in the fuzzy signature concept classification of liver lesions

Ferenc Lilik Melinda Kovacs L. T. Koczy Szilvia Nagy

Publication Name: International Conference on Electrical Computer Communications and Mechatronics Engineering Iceccme 2022

Publication Date: 2022-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Liver is a very unique organ, it has double blood supply, not only through the arteries, but also through the veins. This property makes the contrast material enhanced computer tomography images show very characteristic behavior, depending on the time passed from the adjustment of the contrast material. When diagnosing a nodule in the liver by computer tomography, radiologist experts use multiple images with different delay factors, and generally, five basic characteristic properties of the nodule compared to the normal liver tissues. In the following considerations, we give a simplified model that reproduces the way medical experts take decisions, and offer a possibility to develop a computer aided diagnosis method. The classification of the nodules applies a model with fuzzy signatures, where the aggregation functions in the intermediate nodes are representing the radiologist point of view, while the membership degrees/functions at the leaves of the fuzzy signature's rooted tree are obtained from calculations applying the fuzzy c-means clustering algorithm.

Open Access: Yes

DOI: 10.1109/ICECCME55909.2022.9988684

Local Binary Pattern-Based Fingerprint Matching

P. Földesi Boldizsar Tuu-Szabo Gábor Kovács L. T. Koczy Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2022-01-01

Volume: 959

Issue: Unknown

Page Range: 183-188

Description:

In this paper we propose an image-based fingerprint recognition system. The method is based on Local Binary Pattern features extracted from the region of the fingerprint image around the core point. The experiments on the FVC2002 fingerprint databases show the effectiveness of the proposed approach.

Open Access: Yes

DOI: 10.1007/978-3-030-74970-5_21

On the Selection the Rule Membership Functions and Fuzzy Rule Interpolation

Ferenc Lilik Brigita Sziová Szonja Krisztina Szujo L. T. Koczy Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2022-01-01

Volume: 959

Issue: Unknown

Page Range: 111-118

Description:

In many real physical systems based fuzzy inference systems the rulebase is sparse thus interpolation or the change of the shape of the rules become necessary if the rulebase parameters are selected according to physical parameters of the systems. Often measurements contain noise and outlines which can draw the statistics of the measured data. In the present article based on two independent examples, namely telecommunication line evaluation and colonoscopy image processing, we study the effect of the selection of the rulebase parameters on the effectiveness of stabilized fuzzy KH interpolation.

Open Access: Yes

DOI: 10.1007/978-3-030-74970-5_13

On classical and fuzzy Hough transform in colonoscopy image processing

Brigita Sziová Raneem Ismail L. T. Koczy Szilvia Nagy

Publication Name: IEEE AFRICON Conference

Publication Date: 2021-09-13

Volume: 2021-September

Issue: Unknown

Page Range: Unknown

Description:

Hough transform is used to find lines on edge-filtered images that are given in parametric form. As the fuzzy extension of the Hough transform has been proven to be more robust in environments where the lines to be found by them are not strictly following the formula given by the parametric equation of the Hough transform due to noise and weak and blurred contours, in the following considerations, we study the applicability of the circular fuzzy Hough transform for analyzing colonoscopy pictures and detecting colorectal polyps.

Open Access: Yes

DOI: 10.1109/AFRICON51333.2021.9570897

Application of structural entropy and spatial filling factor in colonoscopy image classification

Brigita Sziová Zoltán Fazekas Szilvia Nagy

Publication Name: Entropy

Publication Date: 2021-08-01

Volume: 23

Issue: 8

Page Range: Unknown

Description:

For finding colorectal polyps the standard method relies on the techniques and devices of colonoscopy and the medical expertise of the gastroenterologist. In case of images acquired through colonoscopes the automatic segmentation of the polyps from their environment (i.e., from the bowel wall) is an essential task within computer aided diagnosis system development. As the number of the publicly available polyp images in various databases is still rather limited, it is important to develop metaheuristic methods, such as fuzzy inference methods, along with the deep learning algorithms to improve and validate detection and classification techniques. In the present manuscript firstly a fuzzy rule set is generated and validated. The former process is based on a statistical approach and makes use of histograms of the antecedents. Secondly, a method for selecting relevant antecedent variables is presented. The selection is based on the comparision of the histograms computed from the measured values for the training set. Then the inclusion of the Rényi-entropy-based structural entropy and the spatial filling factor into the set of input variables is proposed and assessed. The beneficial effect of including the mentioned structural entropy of the entropies from the hue and saturation (H and S) colour channels resulted in 65% true positive and 60% true negative rate of the classification for an advantageously selected set of antecedents when working with HSV images.

Open Access: Yes

DOI: 10.3390/e23080936

Interpolative decisions in the fuzzy signature based image classification for liver CT

Ferenc Lilik Melinda Kovacs Szonja Krisztina Szujo L. T. Koczy Szilvia Nagy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2021-07-11

Volume: 2021-July

Issue: Unknown

Page Range: Unknown

Description:

In computer aided diagnostics image processing and classification plays an essential role. Image processing experts have been developing solutions for different types of problems, that can be related to image processing, however, due to the sensitivity of the data and the high cost of medical experts, these experimental methods usually have very limited use in real medical practice. The databases that are available are very limited, thus the elsewhere usual and extremely effective convolutional neural network or other automated learning methods are not so easy to adjust for medical image processing. To overcome this difficulty, this paper presents an expert knowledge based method which describes the decision structures by fuzzy signatures. Values of various properties of Computer Tomography images as e.g. density or homogeneity are being considered in these signatures that are different in all case of liver diseases. Because of the low number of samples available, fuzzy sets that describes the leafs of the signatures leads to sparse systems, hence interpolation is needed. However further investigations of other interpolation methods are planned, Stabilized Koczy-Hirota interpolation seems to be appropriate.

Open Access: Yes

DOI: 10.1109/FUZZ45933.2021.9494401

Intelligent wavelet based pre-filtering method for ultrasonic sensor fusion inverse algorithm performance optimization

György Kovács Szilvia Nagy

Publication Name: Inventions

Publication Date: 2021-06-01

Volume: 6

Issue: 2

Page Range: Unknown

Description:

Certain obstacle mapping applications require the live evaluation of the measured data to prevent collision with obstacles. The fusion of different or similar sensors usually has a high calculation demand, which increases significantly with the area to be evaluated and the number of sensors. In the present considerations, we propose a wavelet-based adaptive optimization method, which can greatly decrease the number of grid points to be evaluated, and thus the necessary computation time. The basis of the method is to use the fact that the areas to be evaluated mostly face a rather small number of obstacles, which cover a smaller percentage of the whole environment. The first step in a pre-filtering process is the determination of the zones where no obstacles are present. This step can already result in a considerable decrease in the computation time, however with the transformation to polar coordinates, the method will not only be more fitted to the problem to be solved, but the area of the evaluation can also be increased with the same number of grid points. As a last step, we applied wavelet transformation to identify the regions of interest, where the application of a refined raster is necessary, and thus further decreasing the number of grid points where the calculation has to be carried out. We used our previously developed probability-based ultrasonic sensor fusion inverse algorithm to demonstrate the efficiency of the proposed method.

Open Access: Yes

DOI: 10.3390/inventions6020030

On Metrics Used in Colonoscopy Image Processing for Detection of Colorectal Polyps

Raneem Ismail Szilvia Nagy

Publication Name: Smart Innovation Systems and Technologies

Publication Date: 2021-01-01

Volume: 216

Issue: Unknown

Page Range: 137-151

Description:

Colorectal cancer is nowadays the fourth cause of cancer death worldwide. Prevention of colorectal cancer by detection and removal of early stage lesions is of essential importance and has become a public health challenge worldwide. As the screening is carried out mainly by some sort of endoscope, and the endoscopic image processing is an important area of research and development, it is essential to know what kind of measures are used in determining whether polyp finding hit rates or miss rates are acceptable. It is rather natural to match the hit rate measures to the method itself; thus, in this contribution, the most typical polyp detecting methods are summarized shortly together with the metrics they use for evaluation of their results. However, in computer-aided diagnostics, the measure that is used by the medical community might differ from the measures typical in image processing researches. Also, the output of such polyp detecting methods is tested as inputs for active contour methods.

Open Access: Yes

DOI: 10.1007/978-981-33-4676-5_10

On the Applicability of Fuzzy Rule Interpolation and Wavelet Analysis in Colorectal Image Segment Classification

Ferenc Lilik Brigita Sziová Melinda Kovacs L. T. Koczy Szilvia Nagy

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2021-01-01

Volume: 394

Issue: Unknown

Page Range: 243-255

Description:

The automatic detection of colorectal polyps could serve as a visual aid for gastroenterologists when screening the population for colorectal cancer. A fuzzy inference based method was developed for determining whether a segment of an image has polyps. Its antecedent dimensions were the mean pixel intensity, the intensity’s standard deviation, the edge density, the structural entropies and the gradients, not only for the original image segments, but for its wavelet transformed versions. The method performed moderately well, even though the number of the input parameters was very large. In the present contribution we studied, that based on the necessary and usually applied conditions of the applicability of fuzzy rule interpolation, which antecedent dimensions should remain, and how omitting the other input parameters influences the results of the method.

Open Access: Yes

DOI: 10.1007/978-3-030-54341-9_21

The Effects of Preprocessing on Colorectal Polyp Detecting by Fuzzy Algorithm

Brigita Sziová L. T. Koczy Szilvia Nagy

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2021-01-01

Volume: 393

Issue: Unknown

Page Range: 347-357

Description:

In the following study the effects of two image preprocessing methods, namely Gaussian filtering and Wiener filtering, is studied on the results of a fuzzy inference method previously developed by the authors, for determining whether a colonoscopy picture segment contains any colorectal polyp. As earlier results show that less blurry, less compressed and less noisy images tend to be better classifiable, the effects of noise suppression with a Gaussian filter, which makes the images also blurrier, was beneficial on noisy, compressed images, and rather maleficent in good quality pictures. The effects of the Wiener filter, which both decreases noise and enhances edges, did not really manifest in classification improvement.

Open Access: Yes

DOI: 10.1007/978-3-030-47124-8_28

Ultrasonic sensor fusion inverse algorithm for visually impaired aiding applications

György Kovács Szilvia Nagy

Publication Name: Sensors Switzerland

Publication Date: 2020-07-01

Volume: 20

Issue: 13

Page Range: 1-16

Description:

Depth mapping can be carried out by ultrasound measuring devices using the time of flight method. Ultrasound measurements are favorable in such environments, where the light or radio frequency measurements can not be applied due to the noise level, calculation complexity, reaction time, size and price of the device, accuracy or electromagnetic compatibility. It is also usual to apply and fusion ultrasound sensors with other types of sensors to increase the precision and reliability. In the case of visually impaired people, an echolocation based aid for determining the distance and the direction of obstacles in the surroundings can improve the life quality by giving the possibility to move alone and individually in unlearnt or rapidly changing environments. In the following considerations, a model system is presented which can provide rather reliable position and distance to multiple objects. The mathematical model based on the time of flight method with a correction: it uses the measured analog sensor signals, which represent the probability of the presence of an obstacle. The device consists of multiple receivers, but only one source. The sensor fusion algorithm for this setup and the results of indoor experiments are presented. The mathematical model allows the usage, processing, and fusion of the signals of up to an infinite number of sensors. In addition, the positions of the sensors can be arbitrary, and the mathematical model does not restrict them to be placed in regular formations.

Open Access: Yes

DOI: 10.3390/s20133682

Fuzzy rulebase parameter determination for stabilized KH interpolation based detection of colorectal polyps on colonoscopy images

Ferenc Lilik Brigita Sziová Raneem Ismail L. T. Koczy Szilvia Nagy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2020-07-01

Volume: 2020-July

Issue: Unknown

Page Range: Unknown

Description:

In the case of computer aided diagnosis it is advantageous to apply such computational intelligence methods, that can be related to direct measured data by means easily understandable to medical experts. Fuzzy reasoning, if the rulebase is generated from plausible statistical parameters of the image to be analysed, is easy to understand thus can be easily accepted by the society.In the case of colorectal polyps, which might develop into colorectal cancer, thus the population-wide screening would be advisable, more methods are available, but none of them is accepted as standard and effective method. A method based on simple statistical parameters and entropies of image segments is presented, and the effect of determining the rulebase parameters on the efficiency of finding the polyp segment is studied for stabilized Koczy-Hirota rule interpolation.

Open Access: Yes

DOI: 10.1109/FUZZ48607.2020.9177839

The effect of background and outlier subtraction on the structural entropy of two-dimensional measured data

Brigita Sziová Levente Solecki Szilvia Nagy

Publication Name: International Journal of Reasoning Based Intelligent Systems

Publication Date: 2020-01-01

Volume: 12

Issue: 3

Page Range: 200-209

Description:

For colonoscopy images the main information is in the fine structure of the surface of the bowel or colorectal polyps, similarly to the case of combustion engine cylinder surface scans, where the grooving and wear can be detected from the fine pattern superposed to a cylinder curvature. In both cases appear outliers, colonoscopy images have many reflections, whereas the roughness scanners detect small dust particles as well as the micron scale vibrations from the environment. The method presented in this paper takes care of both the problems using histogram stretching together with a special type of filtering. Also, masks are introduced in order to control the effect of the operators. The effects of the processing steps on the structural entropy of the image is also studied, as structural entropies are used in characterisation of the images. By removing the background makes the structural entropies much smaller, and by suppressing the outliers the structural entropies increase.

Open Access: Yes

DOI: DOI not available

On wavelet based enhancing possibilities of fuzzy classification methods

Ferenc Lilik Brigita Sziová Levente Solecki L. T. Koczy Szilvia Nagy

Publication Name: Journal of Automation Mobile Robotics and Intelligent Systems

Publication Date: 2020-01-01

Volume: 14

Issue: 2

Page Range: 32-41

Description:

If the antecedents of a fuzzy classification method are derived from pictures or measured data, it might have too many dimensions to handle. A classification scheme based on such data has to apply a careful selection or processing of the measured results: either a sampling, re-sampling is necessary. or the usage of functions, transfor-mations that reduce the long, high dimensional observed data vector or matrix into a single point or to a low number of points. Wavelet analysis can be useful in such cases in two ways. As the number of resulting points of the wavelet analysis is approximately half at each filters, a consecutive application of wavelet transform can compress the me-asurement data, thus reducing the dimensionality of the signal, i.e., the antecedent. An SHDSL telecommunication line evaluation is used to demonstrate this type of appli-cability, wavelets help in this case to overcome the pro-blem of a one dimensional signal sampling. In the case of using statistical functions, like mean, variance, gradient, edge density, Shannon or Rényi entropies for the extraction of the information from a picture or a measured data set, and they don not produce enough information for performing the classification well enough, one or two consecutive steps of wavelet analysis and applying the same functions for the thus resulting data can extend the number of antecedents, and can dis-till such parameters that were invisible for these functions in the original data set. We give two examples, two fuzzy classification schemes to show the improvement caused by wavelet analysis: a measured surface of a combustion engine cylinder and a colonoscopy picture. In the case of the first example the wear degree is to be deter-mine, in the case of the second one, the roundish polyp content of the picture. In the first case the applied statistical functions are Rényi entropy differences, the structural entropies, in the second case mean, standard deviation, Canny filtered edge density, gradients and the entropies. In all the examples stabilized KH rule interpolation was used to treat sparse rulebases.

Open Access: Yes

DOI: 10.14313/JAMRIS/2-2020/18

Applying fuzzy hough transform for identifying honed microgeometrical surfaces

Brigita Sziová Levente Solecki Balázs Sarkadi-Nagy L. T. Koczy Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2020-01-01

Volume: 819

Issue: Unknown

Page Range: 35-42

Description:

In the measurement of microgeometrical surfaces it is useful if the same location can be found on a surface for two or more different and independent measurements, as in this case not only statistical parameters of the measurements can be compared, but direct differences can be calculated. Honing is a typical surface processing method resulting in pattern consisting of straight valleys crossing at various angles. Honing pattern is of great help to find a special location. The main goal of this article is to find a method that is able to give some characteristic points that can be used for fitting two measured surfaces together. Hough transform is used in finding straight lines in an image or map, thus it could be used for determining crossing points of the honed surface. However, classical Hough transform either finds way too many disturbing lines in the case of a typical honed surface or almost none, depending on the parameter selection. To solve this rapid changing in the number of the resulting lines, we introduced fuzzy Hough transform. If a fuzzified version of the weights of the individual points in the Hough transform is used, the inverse of the transform becomes clearer, resulting in a pattern more suitable for finding the same location on two measured versions of a surface.

Open Access: Yes

DOI: 10.1007/978-3-030-16024-1_5

On wavelet based enhancing possibilities of fuzzy classification methods

Ferenc Lilik Brigita Sziová Levente Solecki L. T. Koczy Szilvia Nagy

Publication Name: Advances in Intelligent Systems and Computing

Publication Date: 2020-01-01

Volume: 945

Issue: Unknown

Page Range: 56-73

Description:

If the antecedents of a fuzzy classification method are derived from pictures or measured data, it might have too many dimensions to handle. A classification scheme based on such data has to apply a careful selection or processing of the measured results: either a sampling, re-sampling is necessary or the usage of functions, transformations that reduce the long, high dimensional observed data vector or matrix into a single point or to a low number of points. Wavelet analysis can be useful in such cases in two ways. As the number of resulting points of the wavelet analysis is approximately half at each filters, a consecutive application of wavelet transform can compress the measurement data, thus reducing the dimensionality of the signal, i.e., the antecedent. An SHDSL telecommunication line evaluation is used to demonstrate this type of applicability, wavelets help in this case to overcome the problem of a one dimensional signal sampling. In the case of using statistical functions, like mean, variance, gradient, edge density, Shannon or Rényi entropies for the extraction of the information from a picture or a measured data set, and they don not produce enough information for performing the classification well enough, one or two consecutive steps of wavelet analysis and applying the same functions for the thus resulting data can extend the number of antecedents, and can distill such parameters that were invisible for these functions in the original data set. We give two examples, two fuzzy classification schemes to show the improvement caused by wavelet analysis: a measured surface of a combustion engine cylinder and a colonoscopy picture. In the case of the first example the wear degree is to be determine, in the case of the second one, the roundish polyp content of the picture. In the first case the applied statistical functions are Rényi entropy differences, the structural entropies, in the second case mean, standard deviation, Canny filtered edge density, gradients and the entropies. In all the examples stabilized KH rule interpolation was used to treat sparse rulebases. The preliminary version of this paper was presented at the 3rd Conference on Information Technology, Systems Research and Computational Physics, 2–5 July 2018, Cracow, Poland [1].

Open Access: Yes

DOI: 10.1007/978-3-030-18058-4_5

Fuzzy Hough transformation in aiding computer tomography based liver diagnosis

Brigita Sziová Melinda Kovacs L. T. Koczy Szilvia Nagy

Publication Name: IEEE AFRICON Conference

Publication Date: 2019-09-01

Volume: 2019-September

Issue: Unknown

Page Range: Unknown

Description:

In the liver many types of roundish lesions can appear, as well as near the liver. Finding the contour of such objects can improve both the segmentation of the liver from its environment, and the segmentation of the lesions within the liver. However, classical Hough transform, which is one of the main methods for finding objects described by a predefined parameterized formula, usually fails to identify these object as they possess not perfectly round or elliptic contours. A fuzzification of the Hough transform is described and suggested for using in image preprocessing for liver diagnosis based on CT images in this paper. Fuzzifying the Hough transform improves the detection of roundish contours.

Open Access: Yes

DOI: 10.1109/AFRICON46755.2019.9133793

Identification and dynamic analysis of crime hot-spots in Hungary by a complex Computer Intelligence approach

P. Földesi Boldizsar Tuu-Szabo Gábor Kovács Gergő Fogarasi L. T. Koczy Szilvia Nagy

Publication Name: Ines 2019 IEEE 23rd International Conference on Intelligent Engineering Systems Proceedings

Publication Date: 2019-04-01

Volume: Unknown

Issue: Unknown

Page Range: 247-252

Description:

In the field of forensic science, crime maps are widely used. The representation of the data and analysis could offer some steps forward for crime prevention. Clustering is able to help identify criminal hot-spots and further analysis designate which require intervention. The aim of this study is to present a first step in the analysis of Hungary-related criminal information.

Open Access: Yes

DOI: 10.1109/INES46365.2019.9109437

On structural entropy and spatial filling factor analysis of colonoscopy pictures

Brigita Sziová János Pipek Szilvia Nagy

Publication Name: Entropy

Publication Date: 2019-03-01

Volume: 21

Issue: 3

Page Range: Unknown

Description:

Colonoscopy is the standard device for diagnosing colorectal cancer, which develops from little lesions on the bowel wall called polyps. The Rényi entropies-based structural entropy and spatial filling factor are two scale- and resolution-independent quantities that characterize the shape of a probability distribution with the help of characteristic curves of the structural entropy-spatial filling factor map. This alternative definition of structural entropy is easy to calculate, independent of the image resolution, and does not require the calculation of neighbor statistics, unlike the other graph-based structural entropies.The distant goal of this study was to help computer aided diagnosis in finding colorectal polyps by making the Rényi entropy based structural entropy more understood. The direct goal was to determine characteristic curves that can differentiate between polyps and other structure on the picture. After analyzing the distribution of colonoscopy picture color channels, the typical structures were modeled with simple geometrical functions and the structural entropy-spatial filling factor characteristic curves were determined for these model structures for various parameter sets. A colonoscopy image analying method, i.e., the line- or column-wise scanning of the picture, was also tested, with satisfactory matching of the characteristic curve and the image.

Open Access: Yes

DOI: 10.3390/e21030256

Wavelet analysis and structural entropy based intelligent classification method for combustion engine cylinder surfaces

Levente Solecki Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2019-01-01

Volume: 794

Issue: Unknown

Page Range: 127-138

Description:

Structural entropy is a good candidate for characterizing roughness of surfaces as it is sensitive not only to the general shape of the surface, but also to the rate of the high and low surface points. Wavelet analysis of the surface can separate the larger-scale behavior from the fine details, and together with the structural entropy it can define a behavior profile for the surface which is typically slightly different for new and for worn tribological surfaces. Also it is important to know whether the method of the surface scan has influence on the structural entropy’s wavelet analysis profile, as the lower cost images based on silicone replica and optical scanner have less sensitivity than the higher cost contact scan of the prepared real surface parts. An intelligent fuzzy classification scheme is introduced to characterize surfaces according to both their degree of wear and method of the surface measurement. The basis of the classification is the structural entropies of the original and the first wavelet transform of the height scan of the new and worn surfaces.

Open Access: Yes

DOI: 10.1007/978-3-030-01632-6_9

Crime “hot-spots” identification and analysis in Hungary by computational intelligence

P. Földesi Boldizsar Tuu-Szabo Gábor Kovács Gergő Fogarasi L. T. Koczy Szilvia Nagy

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2019-01-01

Volume: 16

Issue: 10

Page Range: 137-155

Description:

In the constantly growing and widening field of forensic science, crime maps are used in versatile ways. The representation of the data and analysis could offer some steps toward crime prevention and helps understand patterns, in terms of a timely distribution of crime types. Clustering is able to help identify criminal hot-spots and additional analysis may determine which areas require intervention. The aim of this study is to present an analysis of criminal information related to Hungary, in annual and monthly breakdown.

Open Access: Yes

DOI: 10.12700/APH.16.10.2019.10.9

On the antecedent sets for fuzzy classification of colorectal polyps with stabilized KH interpolation

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2019-01-01

Volume: 796

Issue: Unknown

Page Range: 23-33

Description:

Polyps in the colorectal part of the bowel appear often, and in many cases these polyps can develop into malign lesions, such as cancer. Colonoscopy is the most efficient way to study the inner surface of the colorectum, and doctors usually are able to detect polyps on a motion picture diagnostic session. However, it is useful to have an automated tool that can help drawing attention to given parts of the image, and later a method for classification the polyps can also be developed. Statistical properties of the colour channels of the images are used as antecedents for a fuzzy decision system, together with edge densities and Renyi entropies-based structural entropy. However promising the processed images are, the variation in the preparation of the diagnosis as well as the practice of the operating personnel can lead to images with significantly different noise and distortion level, thus detecting the polyp can be complicated. In the following considerations image groups are presented that have similarities from the polyp detection point of view, and those type of images are also given, which can spoil a well prepared detecting system.

Open Access: Yes

DOI: 10.1007/978-3-030-00485-9_3

The effect of image feature qualifiers on fuzzy colorectal polyp detection schemes using KH interpolation - Towards hierarchical fuzzy classification of coloscopic still images

Brigita Sziová L. T. Koczy Szilvia Nagy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2018-10-12

Volume: 2018-July

Issue: Unknown

Page Range: Unknown

Description:

Previous studies showed that intensities, intensity variation, edge densities, structural entropies of colonoscopy images and their wavelet transforms are good candidates for being selected as antecedents in fuzzy decision methods using KH interpolation for determining whether an image segment contains colorectal polyp segment. In the present consideration, we check which possible antecedent dimensions need interpolation, whether the average and variation of the gradients makes the classification more effective and whether some of the features can be omitted for some classes of images. The method is tested on three available databases consisting of images of three different resolutions, and according to the results, different resolutions, different types of polyps require different classification schemes, thus a hierarchical decision system needs to be built.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2018.8491479

Some remarks on comparing microgeometrical profiles and the application of replicas in microgeometrical measurements

Levente Solecki Szilvia Nagy

Publication Name: Surface Topography Metrology and Properties

Publication Date: 2018-09-25

Volume: 6

Issue: 4

Page Range: Unknown

Description:

First a method for comparing profiles given in the following considerations. The profile comparisons have to be carried out in such position, that their average distance should be the smallest possible. Helmert transform is used for fitting measured points sets to one another in geodesy so that the least square distance of the measured points would be the smallest. However, for Helmert transform corresponding point pairs are to be found, i.e. for each point of one of the profiles has to be found a nearest one on the other profile. Multiple approaches are studied for finding corresponding point to a measured point in a point set. The effectiveness of the Helmert transform and the results of profile comparison are given for profiles of rounded triangle wave shaped regular roughness standards in the most used mechanical roughness range taken by contact stylus and confocal white light optical scanner. As an application, a method for qualifying replica materials is also presented. Our method uses roughness standards of at least three different roughnesses and takes replicas of them. The inverted scanned profiles of the replicas are compared with the scanned profiles of the original surfaces. The comparison uses Helmert transform to fit the two corresponding profiles. The average distance of one of the profile point sets from the other one is calculated by determining the distance of all the points in one profile from the circles given by their three nearest measured points in the other profile. The method is also used for comparing the less noisy stylus scans and the more sensitive optical scans of the original surface in order to determine, whether the noise in the replica scans are due to the replica taking process or to the scanning.

Open Access: Yes

DOI: 10.1088/2051-672X/aadf53

Detecting contours of pathological forms in colonoscopy images using a hybrid method

Plamen Petrov Veska Georgieva Brigita Sziová Szilvia Nagy

Publication Name: Communication Electromagnetics and Medical Application

Publication Date: 2018-01-01

Volume: 2018-October

Issue: Unknown

Page Range: 27-30

Description:

As colonoscopy is needed for screening colorectal polyps, and the first step of classification these polyps is recognizing them, it is worth to research, whether the colonoscopy databases could be improved by image processing and contour detection. In the following considerations a reflection filtering and background subtraction with large-sized mean filter is used as image preprocessing tools, and hybrid method for segmentation of pathological forms, based on template matching and active contour model as contour fitting for segmentation of the image is made.

Open Access: Yes

DOI: DOI not available

On combination of wavelet transformation and stabilized KH interpolation for fuzzy inferences based on high dimensional sampled functions

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: Studies in Computational Intelligence

Publication Date: 2018-01-01

Volume: 758

Issue: Unknown

Page Range: 31-42

Description:

A new approach for inference based on treating sampled functions is presented. Sampled functions can be transformed into only a few points by wavelet analysis, thus the complete function is represented by these several discrete points. The finiteness of the teaching samples and the resulting sparse rule bases can be handled by fuzzy rule interpolation methods, like KH interpolation. Using SHDSL transmission performance prediction as an example, the simplification of inference problems based on large, sampled vectors by wavelet transformation and fuzzy rule interpolation applied on these vectors are introduced in this paper.

Open Access: Yes

DOI: 10.1007/978-3-319-74681-4_3

Improved Method for Predicting the Performance of the Physical Links in Telecommunications Access Networks

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: Complexity

Publication Date: 2018-01-01

Volume: 2018

Issue: Unknown

Page Range: Unknown

Description:

A novel approach is presented which is able to predict the available maximal data transfer rate of SHDSL connections from measured frequency dependent electrical parameters of wire pairs. Predictions are made by a fuzzy inference system. The basis of the operable and tested method will be introduced, then an improved version is shown, in which the problems derived from sampling of continuous functions of electrical parameters are eliminated by wavelet transformation. Also possibilities for simplification of the problem and a way of reducing the dimensions of the applied rule bases are presented. As the set of the measured data leads to sparse rule bases, handling of sparseness is unavoidable. Two different ways - fuzzy interpolation and various membership functions - will be introduced. The presented methods were tested by measurements in real telecommunications access networks.

Open Access: Yes

DOI: 10.1155/2018/3685927

Contact problems in GaAs-based solar cells

Ákos Nemcsics Antal Ürmös Zoltán Farkas L. Dobos Szilvia Nagy

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2018-01-01

Volume: 15

Issue: 6

Page Range: 99-124

Description:

The present work deals with contact problems of GaAs-based solar cells. In the introduction the most basic GaAs-based solar cell structures are introduced. Then, the energy and electronic properties are investigated. In the third part of this publication, the technological aspects of the metallization are discussed. Here the surface patterns are investigated, that are formed at the surface of the Au/GaAs and Au/TiN/GaAs material systems, as the effect of the annealing process. The further aim of these investigations to investigate, how the properties of ohmic contact depends on the properties of the material system. If these relations are known, the relationships between different morphologies and their electric qualities will be also known.

Open Access: Yes

DOI: 10.12700/APH.15.6.2018.6.6

Entropy based fuzzy classification and detection aid for colorectal polyps

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: 2017 IEEE AFRICON Science Technology and Innovation for Africa AFRICON 2017

Publication Date: 2017-11-03

Volume: Unknown

Issue: Unknown

Page Range: 78-82

Description:

Colorectal polyps affect a large percentage of the population all over the world, and they can be a basis for more serious conditions such as cancers. As the most reliable method for detecting a polyp in the lower bowel tract is colonoscopy, more and more image processing experiments appear that help to find or characterize such a lesion. The social benefit of such methods is clear, any aid in detecting pre-cancer states saves lives. In the present considerations a fuzzy decision method for finding polyps on a colonoscopy image is presented. As a first step, the image taken during the colonoscopy is cut into tiles of size N by N, thus a rough localization of the lesion within the picture is also possible. The antecedent dimensions consist of statistical characteristics of the colour channels of the tiles, their Renyi entropies, edge density and fitted polynomial coefficients. The method's dependence on the tile-size within the images are also studied, and the success rate increases with the decrease of the tile size between 70 by 70 and 20 by 20 tile sizes.

Open Access: Yes

DOI: 10.1109/AFRCON.2017.8095459

Applicability of various wavelet families in fuzzy classification of access networks' telecommunication lines

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2017-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The future of the smart society sets challenges for all types of existing telecommunication networks and links. For ensuring the optimal utilization of these networks precise performance predictions are necessary, especially in case of the symmetrical access networks with rather limited transmission capacity. It is also important to harness the already established infrastructure as long as it is technically possible, so that the use of the environmental resources would be minimal and the economical advantages would be maximal. In performance prediction of telecommunication links the high-dimensional input data, like the insertion loss spectrum, should be compessed. After reducing the dimension of the antecedent set, a fuzzy inference can be carried out for each of the lines. As the number of lines used for building the fuzzy sets is finite and the supports of the fuzzy set do not cover the whole space, a stabilized KH interpolation is used in the decision process. Wavelets constitute the basis of methods for compressing and analyzing data in many fields of science and technology. For the reduction of the input dimension, wavelets proved to be an effective tool. The applicability of various wavelet families with different sizes of filter coefficient sets are tested in the following considerations, with the result, that the wavelet type does not play an essential role as well as the length of the wavelets. Only the deepness of the wavelet transform influences essentially the goodness of the prediction: the remaining number of points should be 4 after the transformation.

Open Access: Yes

DOI: 10.1109/FUZZ-IEEE.2017.8015644

The effect of wavelet analyis on entropy based fuzzy classification of colonoscopy images

Brigita Sziová L. T. Koczy Szilvia Nagy

Publication Name: Iwaciii 2017 5th International Workshop on Advanced Computational Intelligence and Intelligent Informatics

Publication Date: 2017-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Colorectal polyp detection is important in preventing cancer. Structural entropy can detect different structures of distributions, such as image pixel brightness. Wavelet analysis can help in separating large-scale and fine resolution behaviour. In the method presented in this paper, the colonoscopy images are separated into segments, and a classification scheme is built in order to determine, whether there is a polyp part in the image segment or not. Without wavelet analysis edge density and structural entropy can be a basis of fuzzy classification for the polyp content of only good quality colonoscopy images, and still has about 10 percent false classification. In this contribution the effect of wavelet analysis on the classification scheme is studied.

Open Access: Yes

DOI: DOI not available

The coupled cluster method and entanglement in three fermion systems

Gábor Sárosi János Pipek Péter Lévay Szilvia Nagy

Publication Name: Journal of Mathematical Physics

Publication Date: 2017-01-01

Volume: 58

Issue: 1

Page Range: Unknown

Description:

The Coupled Cluster (CC) and full CI expansions are studied for three fermions with six and seven modes. Surprisingly the CC expansion is tailor made to characterize the usual stochastic local operations and classical communication (SLOCC) entanglement classes. It means that the notion of a SLOCC transformation shows up quite naturally as a one relating the CC and CI expansions, and going from the CI expansion to the CC one is equivalent to obtaining a form for the state where the structure of the entanglement classes is transparent. In this picture, entanglement is characterized by the parameters of the cluster operators describing transitions from occupied states to singles, doubles, and triples of non-occupied ones. Using the CC parametrization of states in the seven-mode case, we give a simple formula for the unique SLOCC invariant I. Then we consider a perturbation problem featuring a state from the unique SLOCC class characterized by I. For this state with entanglement generated by doubles, we investigate the phenomenon of changing the entanglement type due to the perturbing effect of triples. We show that there are states with real amplitudes such that their entanglement encoded into configurations of clusters of doubles is protected from errors generated by triples. Finally we put forward a proposal to use the parameters of the cluster operator describing transitions to doubles for entanglement characterization. Compared to the usual SLOCC classes, this provides a coarse grained approach to fermionic entanglement.

Open Access: Yes

DOI: 10.1063/1.4974510

Multiresolution modeling of cavity resonators in microwave systems

András Fehér Brigita Sziová János Pipek Szilvia Nagy

Publication Name: 2016 13th International Conference on Synthesis Modeling Analysis and Simulation Methods and Applications to Circuit Design Smacd 2016

Publication Date: 2016-07-25

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Multiresolution analysis or wavelet analysis provides a toolbox not only for signal processing, but also for synthesis of complex systems. Wavelets can be used for modeling complex parts of microwave circuits, such as cavity resonators. The differential equations describing the physical behavior of the device can be discretized using multiple resolutions simultaneously, i.e., high resolutions, where the details of the geometry demand it, and low resolutions, where the geometry is smooth. Using wavelet analysis offers the possibility of systematic and adaptive refinement, where the result is not sufficiently precise. Our method gives an approximation for the error of the solution in order to make it possible to decide, whether refinements are necessary.

Open Access: Yes

DOI: 10.1109/SMACD.2016.7520651

Optimization of the prediction of second refined wavelet coefficients in electron structure calculations

Brigita Sziová János Pipek Szilvia Nagy

Publication Name: Open Physics

Publication Date: 2016-01-01

Volume: 14

Issue: 1

Page Range: 643-650

Description:

In wavelet-based solution of eigenvalue-type differential equations, like the Schrödinger equation, refinement in the resolution of the solution is a costly task, as the number of the potential coefficients in the wavelet expansion of the solution increases exponentially with the resolution. Predicting the magnitude of the next resolution level coefficients from an already existing solution in an economic way helps to either refine the solution,or to select the coefficients, which are to be included into the next resolution level calculations, or to estimate the magnitude of the error of the solution. However, after accepting a solution with a predicted refinement as a basis, the error can still be estimated by a second prediction, i.e., from a prediction to the second finer resolution level coefficients. These secondary predicted coefficients are proven to be oscillating around the values of the wavelet expansion coefficients of the exact solution. The optimal averaging of these coefficients is presented in the following paper using a sliding average with three optimized coefficients for simple, one-dimensional electron structures.

Open Access: Yes

DOI: 10.1515/phys-2016-0063

Wavelet based fuzzy rule bases in pre-qualification of access networks' wire pairs

Ferenc Lilik L. T. Koczy Szilvia Nagy

Publication Name: IEEE AFRICON Conference

Publication Date: 2015-11-18

Volume: 2015-November

Issue: Unknown

Page Range: Unknown

Description:

Even though the penetration of the fibre optical cables into telecommunication access networks seems to be accelerated, most of the customers are connected to the central office or to the telecommunication nodes by the copper wire pairs of the old telephone network. Until the replacement of the lines, their needs for modern high speed data communications services can be fulfilled by these symmetrical wire pairs. Equipment manufacturers produce equipments of the latest technologies for these networks (e.g. VDSL2), however pre-qualification of wire pairs of access networks is also essential, as the estimation of the performance gives the possibility to optimize the offered ensemble of services for telecommunications service providers. Our previous performance evaluation method based on fuzzy rule bases at discrete values of the insertion loss at 6 characteristic frequencies is improved by wavelet analysis. We have also proved, that the fine structure of the insertion loss spectrum does not play role in the achievable data transfer rate of the lines.

Open Access: Yes

DOI: 10.1109/AFRCON.2015.7332034

An economic prediction of the finer resolution level wavelet coefficients in electronic structure calculations

János Pipek Szilvia Nagy

Publication Name: Physical Chemistry Chemical Physics

Publication Date: 2015-01-01

Volume: 17

Issue: 47

Page Range: 31558-31565

Description:

In wavelet based electronic structure calculations, introducing a new, finer resolution level is usually an expensive task, this is why often a two-level approximation is used with very fine starting resolution level. This process results in large matrices to calculate with and a large number of coefficients to be stored. In our previous work we have developed an adaptively refined solution scheme that determines the indices, where the refined basis functions are to be included, and later a method for predicting the next, finer resolution coefficients in a very economic way. In the present contribution, we would like to determine whether the method can be applied for predicting not only the first, but also the other, higher resolution level coefficients. Also the energy expectation values of the predicted wave functions are studied, as well as the scaling behaviour of the coefficients in the fine resolution limit.

Open Access: Yes

DOI: 10.1039/c5cp01214g

An economic prediction of refinement coefficients in wavelet-based adaptive methods for electron structure calculations

János Pipek Szilvia Nagy

Publication Name: Journal of Computational Chemistry

Publication Date: 2013-03-05

Volume: 34

Issue: 6

Page Range: 460-465

Description:

The wave function of a many electron system contains inhomogeneously distributed spatial details, which allows to reduce the number of fine detail wavelets in multiresolution analysis approximations. Finding a method for decimating the unnecessary basis functions plays an essential role in avoiding an exponential increase of computational demand in wavelet-based calculations. We describe an effective prediction algorithm for the next resolution level wavelet coefficients, based on the approximate wave function expanded up to a given level. The prediction results in a reasonable approximation of the wave function and allows to sort out the unnecessary wavelets with a great reliability. © 2012 Wiley Periodicals, Inc.

Open Access: Yes

DOI: 10.1002/jcc.23154

Plausible quantum-mechanical interpretations of RHEED oscillation

Ákos Nemcsics Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2012-01-27

Volume: 86

Issue: 6

Page Range: 620-622

Description:

In this paper the oscillations of reflection high-energy electron diffraction is investigated on the basis of the electron complementarity principle and quantum entanglement. The intensity oscillations during the growth process can be explained by the change of the surface morphology, which is caused by the changing of the experimental conditions. The experimental conditions affect both the description of the interaction on the surface and the behavior of the electrons as quantum mechanical entities, i.e., if their particle-like or wave-like properties dominate. The interpretation of these phenomena can be made plausible with the help of the idea of quantum entanglement. © 2011 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2011.07.020

Wavelet analysis and finite difference modeling of multiple reflections in transmission lines

A. Bekefi András Fehér Szilvia Nagy

Publication Name: 2nd Middle East Conference on Antennas and Propagation Mecap 2013

Publication Date: 2012-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

No description provided

Open Access: Yes

DOI: 10.1109/MECAP.2012.6618201

Error estimation of wavelet based modeling of electromagnetic waves in waveguides and resonators

András Fehér János Pipek Szilvia Nagy

Publication Name: 2nd Middle East Conference on Antennas and Propagation Mecap 2013

Publication Date: 2012-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Wavelets provide an effective toolbox for solving differential equations by representing the continuous functions by their wavelet expansion coefficients and the corresponding differential equations by discrete matrix equations. The wavelet basis functions are organized into resolution levels of different frequency terms at different locations, and the main advantage of the wavelet expansion representation is that the resolution level can be different at different locations, if the solution function contains higher frequency terms in one place and restricted to lower frequencies at other places. Wavelet based differential equation solving methods can be adaptive, it is possible to refine the solution locally, if the precision is not sufficient at some regions. In the present work a simple method for estimating the next resolution level wavelet coefficients is presented. Predicting the approximate value of these coefficients makes it possible to select the minimal set of wavelet basis functions for the next resolution level solution in a computationally economic way, or in the last resolution levels it can substitute the next level solution of the matrix equation. © 2012 IEEE.

Open Access: Yes

DOI: 10.1109/MECAP.2012.6618193

Developing sample holders for measuring shielding effectiveness of thin layers on compound semiconductor substrates

András Fehér Szilvia Nagy

Publication Name: Progress in Electromagnetics Research Symposium

Publication Date: 2011-12-26

Volume: Unknown

Issue: Unknown

Page Range: 1637-1641

Description:

Wavelet or multiresolution analysis (MRA) is widely applied in advanced data compression algorithms, solving differential equations, and some approaches have already applied this technique in describing electromagnetic fields. The main advantage of the application of MRA is its adaptivity and flexibility. Since the details of the electromagnetic field are not distributed equally over different parts of the system (i.e., the description of some parts need finer details, while others are easily represented at low resolution level), locally different resolution levels can be applied. Wavelet based adaptive solution possibilities of differential equations of electromagnetic field are investigated in the followings. The adaptivity of the method means in this case, that the refinement level of the solution can be increased locally, if the accuracy needs it, during the calculations. The applicability of the eigenvalue-type differential equation solving method is illustrated by solution of microwave wave-equations of cavity resonators.

Open Access: Yes

DOI: DOI not available

Structural entropy based localization study of wavelet transformed AFM images for detecting background patterns

András Fehér László Milán Molnár Szilvia Nagy

Publication Name: Progress in Electromagnetics Research Symposium

Publication Date: 2011-12-26

Volume: Unknown

Issue: Unknown

Page Range: 1284-1288

Description:

By defining the structural entropy the von Neumann entropy of a charge distribution on a finite grid is divided into two parts. The first one, the extension entropy, is simply the logarithm of the occupation number (i.e., the number of the average grid sites occupied by the charge distribution), while the second part is the structural entropy itself. On a structural entropy versus participation ratio map the different types of localizations follow different, well characterized curves, and every distribution is represented by a vector on the map. By a structural entropy-filling factor map of any charge distributions on a finite grid (e.g., finite representation of an electron density, or a grayscale atomic force microscope (AFM) image) superstructures of different scale topologies with different decay types can be traced as well. However it is rather hard to distinguish elements of an additive superstructure, especially if the numerical parameters of the different scale patterns are necessary. In the AFM practice the background patterns are sometimes hard to compensate, and by simple structural entropy based calculations it is almost impossible to separate the superstructure of the atomic scale and the image-scale pattern. The reason is the following. Superstructures manifest on the structural entropy map as sum of the sub-structures vector, thus since none of the structures are known, only the sum of their vectors, the sub-vectors are not unique. Multiresolution or wavelet analysis (MRA) uses a system of basis functions with various time and frequency (space and spatial frequency) parameters for expanding functions. This system makes the time-frequency localization possible. Using some selected MRA resolution levels of the AFM image and carrying out the structural entropy based localization study on each of these levels will determine the decay type of the image at the length scales corresponding to the selected frequencies. This approach is promising for determining the large-scale patterns on AFM pictures.

Open Access: Yes

DOI: DOI not available

Topology analysis of scanning microscope images with structural entropy and discrete wavelet transform

András Fehér Szilvia Nagy

Publication Name: International Conference on Systems Signals and Image Processing

Publication Date: 2011-11-02

Volume: Unknown

Issue: Unknown

Page Range: 101-104

Description:

Topology free structure of scanning electron microscopy images of heat treated, metallized compound semiconductor surfaces are studied using structural entropy based analysis. The scale dependence and the possible superstructures are determined by wavelet transforming the images before the localization type detection. The studied images are taken in-situ during a thermalization experiment, using GaAs as a substrate and gold, zinc and SiO2 layers of 60 to 100 nm thickness. © 2011 Univ of Sarajevo.

Open Access: Yes

DOI: DOI not available

On wavelet based modeling of radio frequency circuits, parts and electromagnetic fiels

András Fehér Szilvia Nagy

Publication Name: 2010 11th International Workshop on Symbolic and Numerical Methods Modeling and Applications to Circuit Design Sm2acd 2010

Publication Date: 2010-12-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Multiresolution or wavelet analysis is widely used in advanced data compression algorithms, and some approaches applied this technique in describing electromagnetic fields. The main goal of the application of MRA is its flexibility, i.e., since the details of the electromagnetic field are not distributed equally over different parts of the system, thus locally different resolution level can be applied. Wavelet based adaptive solution possibilities of differential equations of electromagnetic field are investigated in the followings. The adaptivity of the method means in this case, that the refinement level of the solution can be increased locally, if the accuracy needs it, during the calculations. ©2010 IEEE.

Open Access: Yes

DOI: 10.1109/SM2ACD.2010.5672288

A wavelet-based adaptive method for determining eigenstates of electronic systems

János Pipek Szilvia Nagy

Publication Name: Theoretical Chemistry Accounts

Publication Date: 2010-03-01

Volume: 125

Issue: 3-6

Page Range: 471-479

Description:

The possibilities for reducing the necessary computation power in wavelet-based electronic structure calculations are studied. The expansion of the expectation values of energy operators, the integrals of basis functions are mostly system-independent, consequently it is not necessary to compute them in each calculations. Fixed building blocks, such as a parameterized expansion of the nuclear and electron-electron cusp can reduce the amount of necessary calculation. An algorithm for local expansion refinement is also given. It is possible to determine the significant expansion coefficients of a high resolution level without solving the Schrödinger equation using only lower resolution results. © Springer-Verlag 2009.

Open Access: Yes

DOI: 10.1007/s00214-009-0653-6

Fractal and structural entropy calculations on the epitaxially grown fulleren structures with the help of image processing

Péter Turmezei Ákos Nemcsics I. Mojzes Szilvia Nagy

Publication Name: Sisy 2009 7th International Symposium on Intelligent Systems and Informatics

Publication Date: 2009-12-01

Volume: Unknown

Issue: Unknown

Page Range: 65-67

Description:

Molecular beam epitaxially grown fullerene layers are investigated with the help of image processing. The layered structures are studied in morphological respect. The individual layer morphologies are derived from the atomic force microscopy picture of the surface. The pattern morphology of the certain layers is analysed by box counting method. The surface morphology shows fractal behaviour. The pattern of each layer shows different dimension. The actual dimension depends on the actual distance of the layer from the substrate. The change of the dimension is attributed to the change of the binding behaviour. The topology of the surface is also studied using participation ratio and structural entropy calculations. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/SISY.2009.5291194

Fractal properties of gold, palladium and gold-palladium thin films on InP

Antal Ürmös Bernadett Varga I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 247-250

Description:

Thermal interaction of indium phosphide (InP) bulk compound semiconductor with thin gold metal films was investigated in the course of the present work. The interaction of the InP/Au system resulted in a pattern showing fractal dimensions. The temperature dependence of the fractal parameters was investigated in a broad temperature range from 200 to 600 °C. No significant temperature dependence of the fractal dimension was observed. The same calculations will be presented for Au/InP and AuPd/InP systems. Our calculations show that the Pd-based contacts have a different behaviour than AuGe metallization where a strong temperature dependence of the fractal number was observed earlier. Another topology measure, the structural entropy is also calculated for the samples. The structural entropy is usually applied for determining the type of the localization of charge distributions, but it can also be used for generalized charges, such as the lightness of the pixels of an electron microscopy picture. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.004

Structural entropy in detecting background patterns of AFM images

László Milán Molnár I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 179-183

Description:

Structural entropy was developed for detecting the type of localization in charge distributions on a finite grid, especially in mesoscopic electronic systems. However, it is possible to detect and analyze superstructures, i.e., topologies consisting of more structures with different types of localization properties. In the definition of the structural entropy, the von Neumann entropy of the system is divided into two parts: first, the extension entropy, which is simply the logarithm of the occupation number; the second part is the structural entropy. On a structural entropy versus logarithm of the spatial filling factor map, the different types of localizations follow different, well-characterized curves. Spatial filling factor measures the percentage of the "filled" (i.e., high intensity) pixels of the image. An atomic force microscopy (AFM) image can be interpreted as some kind of charge distribution on a grid: after normalization, the darkness (or lightness) of the pixels fulfills all the necessary conditions. AFM image artifacts can be detected by plotting the structural entropy versus the logarithm of the spatial filling factor maps of the images. Not only the type of an added large-scale Gaussian, parabolic, exponential, or other function can be identified, but also by careful study of the curves belonging to the structures, the parameters can be detected, too. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.025

Fractal properties of AlGeNi layers on GaAs surfaces

László Milán Molnár Bernadett Varga I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 251-253

Description:

The thermal interactions of thin AlGe and AlNiGe layers with a bulk GaAs monocrystal were investigated. The heat treatment of these systems was carried out in the working chamber of a scanning electron microscope. The SEM pictures were analysed using a fractal mathematical technique. It was found that the surface of the samples has fractal character. No temperature dependence of the fractal dimension was observed. The samples were also studied using the structural entropy versus filling factor maps of the samples in order to find their localization properties. The SEM pictures of AlGe perform mostly as a Gaussian functions, whereas the AlNiGe samples show usually a behaviour with exponential decay. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.005

Investigation of the surface morphology on epitaxially grown fullerene structures

Ákos Nemcsics R. Adelung I. Mojzes L. Kipp Szilvia Nagy S. Woedtke R. Schwedhelm

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 152-154

Description:

Fullerene layers molecular beam epitaxially grown on, a vanadium-selenide substrate are investigated and the morphology of the layered structures is studied. The individual layer morphologies are derived from the atomic force microscopy picture of the surface. The pattern morphology of certain layers is analyzed by a box counting method. The surface morphology shows fractal behaviour. The pattern of each layer shows different dimensions. The actual dimension depends on the actual distance of the layer from the substrate. The change of the dimension is attributed to the change of the binding behaviour. The topology of the surface is also studied using participation ratio and structural entropy calculations. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.060

The kinetic energy operator in the subspaces of wavelet analysis

János Pipek Szilvia Nagy

Publication Name: Journal of Mathematical Chemistry

Publication Date: 2009-06-01

Volume: 46

Issue: 1

Page Range: 261-282

Description:

At any resolution level of wavelet expansions the physical observable of the kinetic energy is represented by an infinite matrix which is "canonically" chosen as the projection of the operator - Δ/2 onto the subspace of the given resolution. It is shown, that this canonical choice is not optimal, as the regular grid of the basis set introduces an artificial consequence of its periodicity, and it is only a particular member of possible operator representations. We present an explicit method of preparing a near optimal kinetic energy matrix which leads to more appropriate results in numerical wavelet based calculations. This construction works even in those cases, where the usual definition is unusable (i.e., the derivative of the basis functions does not exist). It is also shown, that building an effective kinetic energy matrix is equivalent to the renormalization of the kinetic energy by a momentum dependent effective mass compensating for artificial periodicity effects. © 2008 Springer Science+Business Media, LLC.

Open Access: Yes

DOI: 10.1007/s10910-008-9458-4

Some remarks to the nanowires grown on III-V substrate

Ákos Nemcsics László Milán Molnár I. Mojzes Zsolt J. Horváth Szilvia Nagy Eniko Horváth

Publication Name: Asdam 2008 Conference Proceedings of the 7th International Conference on Advanced Semiconductor Devices and Microsystems

Publication Date: 2008-12-01

Volume: Unknown

Issue: Unknown

Page Range: 215-218

Description:

In the present work nanowires are investigated, which were prepared with the help of encapsulated metal induced growth method on GaAs and InP substrate. As our former investigations how, we can receive nanowires with substrate-like composition in the case of InP. In the case of GaAs substrate the situation is entirely different, while the growth technology in both cases was the same. The difference between the nanoproducts in the cases of different substrates originate in the reactivity of the components, which is explained in the following considerations. Furthermore we have observed that the diameter of the nanowires depends on the electron energy of the irradiation. If the electron beam was 5 kV and 20 kV, the diameter lasting increases and decreases, respectively. This effect can be explained by the change of the nanowires structure influenced by the electron beam. © 2008 IEEE.

Open Access: Yes

DOI: 10.1109/ASDAM.2008.4743320

Artifacts of grid-based electron structure calculations

János Pipek Szilvia Nagy

Publication Name: Chemical Physics Letters

Publication Date: 2008-10-13

Volume: 464

Issue: 1-3

Page Range: 103-106

Description:

Electron structure calculations over equidistant grids represent physical observables by matrices usually chosen as the projection of the corresponding operator in the Schrödinger picture onto the subspace expanded by the basis set of the given grid resolution. It is shown that any matrix representation compatible with the translational symmetry of the lattice suffers from essential difficulties. Especially the momentum and related operators like the kinetic energy show anomalous behavior, moreover, the required canonical commutation relation can never be satisfied. © 2008 Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.cplett.2008.08.091

Heat treatment parameters effecting the fractal dimensions of AuGe metallization on GaAs

Csaba Dominkovics János Pipek L. Dobos Gábor Harsányi I. Mojzes Szilvia Nagy

Publication Name: Applied Physics Letters

Publication Date: 2007-08-24

Volume: 91

Issue: 7

Page Range: Unknown

Description:

Correlation was detected between the thermal treatment parameters of the AuGe-GaAs system and surface fractal structure. Structural entropic calculations were used to confirm the results obtained by fractal calculations. © 2007 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.2768911

Analysis of morphology changes of heat treated metallization of compound semiconductors by the fast wavelet-transform based on B-Spline

K. A. Demcu M. Schusztera L. Dobos I. Mojzes Szilvia Nagy

Publication Name: Journal of Optoelectronics and Advanced Materials

Publication Date: 2007-01-01

Volume: 9

Issue: 7

Page Range: 2241-2244

Description:

Heat treatment of metallized compound semiconductors results in generation of Ohmic contacts. The morphology changes of the surface during the thermal treatment can be observed by scanning electron microscope. According to our previous results these patterns show fractal character. The fractal dimension of a self-similar object can be calculated using the toolbox of fast wavelet-transform. A method is presented for analyzing the electron microscopic images of the heat treated samples by a fast wavelet-transform based algorithm using the filter coefficients of the two dimensional B-Spline functions. A connection between the dimension values of the patterns and the temperatures of the heat treating are shown.

Open Access: Yes

DOI: DOI not available

Refinement trajectory and determination of eigenstates by a wavelet based adaptive method

János Pipek Szilvia Nagy

Publication Name: Journal of Chemical Physics

Publication Date: 2006-11-13

Volume: 125

Issue: 17

Page Range: Unknown

Description:

The detail structure of the wave function is analyzed at various refinement levels using the methods of wavelet analysis. The eigenvalue problem of a model system is solved in granular Hilbert spaces, and the trajectory of the eigenstates is traced in terms of the resolution. An adaptive method is developed for identifying the fine structure localization regions, where further refinement of the wave function is necessary. © 2006 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.2363368

ModRTU InjectX: A Command Injection Simulation Tool for Industrial Cybersecurity Research

Zoltán Dobrády T. Hidvégi Szilvia Nagy

Publication Name: 60th International Scientific Conference on Information Communication and Energy Systems and Technologies Icest 2025 Proceedings

Publication Date: 2025-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

ModRTU_InjectX is a Python-based research tool with a graphical user interface, specifically designed for real-time monitoring, analysis, and command injection simulation within Modbus RTU industrial communication systems. The platform enables users to craft custom data packets and inject them into the serial communication channel using event-driven logic, effectively modelling realistic cyberattack scenarios. All communication is logged and can be exported in structured formats, making the system ideal for creating annotated datasets for training and validating machine learning-based intrusion detection systems. The tool supports parallel injection block configurations, evaluates attack effectiveness, and provides detailed statistical summaries. ModRTU_InjectX serves as a valuable contribution to the research infrastructure for industrial cybersecurity.

Open Access: Yes

DOI: 10.1109/ICEST66328.2025.11098380

The Relationship Between EMF Exposure and MIMO Systems, and the Exposure Advantages of Lowband Massive MIMO System

Péter Prukner Kornél Merkli Szilvia Nagy

Publication Name: Telecom

Publication Date: 2025-09-01

Volume: 6

Issue: 3

Page Range: Unknown

Description:

With the advancement of mobile communications, technologies based on high-element-count antenna systems—such as massive Multiple Input Multiple Output (massive MIMO)—are playing an increasingly important role in enhancing network capacity. However, they introduce new challenges in the measurement and evaluation of electromagnetic field (EMF) exposure. This study presents a detailed, laboratory-based methodology for assessing EMF exposure in cellular systems using Single Input Single Output (SISO) and MIMO technologies. To address the limitations of traditional exposure assessment techniques—particularly under the conditions introduced by 5G and active antenna systems—a shielded test environment with directional antennas was developed and applied across lowband and midband frequency ranges (700–2100 MHz). Downlink electromagnetic power density was measured under standardized modulation, coding, and bandwidth settings for both SISO and MIMO configurations. The results show that MIMO technology does not lead to a significant increase in EMF exposure compared to SISO, with average differences remaining below 1 dB. Moreover, in lower-frequency bands, massive MIMO systems can ensure the required user capacity at significantly lower transmission power, resulting in more than 15 dB reductions in EMF exposure. These findings confirm the potential of massive MIMO to enhance network performance while reducing the level of electromagnetic exposure.

Open Access: Yes

DOI: 10.3390/telecom6030063