Search Everything

Tip: Search using "First Name + Last Name", e.g.
János Kiss instead of Kiss János.

Publications - 6374

Statistical Analysis of the Performance of the State-of-the-Art Methods for Solving TSP Variants

Peter Foldesi Boldizsar Tuu-Szabo Laszlo T. Koczy

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

Publication Date: 2019-01-01

Volume: 11909 LNAI

Issue: Unknown

Page Range: 255-262

Description:

In this paper we analyze the efficiency of the state-of-the-art methods for solving two TSP variants, the Traveling Salesman Problem with Time Windows and one-commodity Pickup-and-Delivery Traveling Salesman Problem. Three models (polynomial, exponential, square-root exponential) were fitted to the mean run times of each method. The parameters of the curves, the R2-values and the RMSE values were compared.

Open Access: Yes

DOI: 10.1007/978-3-030-33709-4_23

Are collision and crossing course surrogate safety indicators transferable? A probability based approach using extreme value theory

Haneen Farah Marjan Hagenzieker Aliaksei Laureshyn Attila Borsos

Publication Name: Accident Analysis and Prevention

Publication Date: 2020-08-01

Volume: 143

Issue: Unknown

Page Range: Unknown

Description:

In order to overcome the shortcomings of crash data a number of surrogate measures of safety have been developed and proposed by various researchers. One of the most widely used temporal indicators is time-to-collision (TTC) which requires the road users to be on a collision course. Road users that are strictly speaking not on a collision course actually might behave and take evasive actions as if they were, thus indicating that such near-miss situations might also be relevant for safety analysis. Taking that into account, a more flexible indicator T2, which does not require the two vehicles to be on a collision course, describes the expected time for the second road user to arrive at the conflict point. Recently extreme value theory (EVT) offering two approaches, block maxima (BM) and Peak over Threshold (POT), has been applied in combination with surrogate indicators to estimate crash probabilities. Most of this research has focused on testing BM and POT as well as validating various surrogate safety indicators by comparing model estimates to actual crash frequencies. The comparison of collision course indicators with indicators including crossing course interactions and their performance using EVT has not been investigated yet. In this study we are seeking answers to under what conditions these indicators perform better and whether they are transferable. Using data gathered at a signalized intersection focusing on left-turning and straight moving vehicle interactions our analysis concluded that the two indicators are transferable with stricter threshold values for T2 and that POT gives more reasonable results.

Open Access: Yes

DOI: 10.1016/j.aap.2020.105517

Evaluation of Questionnaires by Combining Fuzzy Signatures, Factor Analysis and Least Squares Method

Dalia Susniene Márta Konczos Szombathelyi Szabolcs Ramhap Ojaras Purvinis Laszlo T. Koczy

Publication Name: Ines 2020 IEEE 24th International Conference on Intelligent Engineering Systems Proceedings

Publication Date: 2020-07-01

Volume: Unknown

Issue: Unknown

Page Range: 215-218

Description:

A survey based on a standard questionnaire on employee satisfaction was carried out in Hungary. The questionnaire was developed by international university research consortium. The qualitative data were collected from 1159 respondents. The subjective and therefore inexact answers represented in the Likert scale were mapped into fuzzy membership degrees. The article presents a method that consists of the combination of factor analysis and the least square method, applied for developing the fuzzy signature characterizing the employees' behavioural engagement.

Open Access: Yes

DOI: 10.1109/INES49302.2020.9147125

Benchmarking methodology for stateful NAT64 gateways

Keiichi Shima Kenjiro Cho Gábor Lencse

Publication Name: Computer Communications

Publication Date: 2023-10-01

Volume: 210

Issue: Unknown

Page Range: 256-272

Description:

The benchmarking of Network Address and Protocol Translation from IPv6 clients to IPv4 servers (stateful NAT64) gateways is challenging from a methodological point of view because the state of the art benchmarking standards have some requirements that are conflicting when applied to stateful NAT64 gateways. In this paper, several methodological gaps are pointed out and a benchmarking methodology is proposed, which is applicable for any stateful NATxy gateways, where x and y are in {4, 6}. It bridges all the gaps by reconciling the conflicting requirements and facilitating the execution of the industry standard benchmarking measurement procedures (throughput, latency, frame loss rate, packet delay variation) with stateful NATxy gateways. New performance metrics specific to stateful testing are also defined: maximum connection establishment rate, connection tear down rate, and connection tracking table capacity. The proposed methodology is suitable for examining the scalability of the stateful NATxy gateways, too. The methodology is validated by applying it to the benchmarking of three radically different stateful NAT64 implementations: Jool, tayga plus iptables, and OpenBSD Packet Filter (PF). The details of the measurements and their results are fully disclosed.

Open Access: Yes

DOI: 10.1016/j.comcom.2023.08.009

Intelligent Fuzzy Traffic Signal Control System for Complex Intersections Using Fuzzy Rule Base Reduction

Tamrat Delessa Chala Laszlo T. Koczy

Publication Name: Symmetry

Publication Date: 2024-09-01

Volume: 16

Issue: 9

Page Range: Unknown

Description:

In this study, the concept of symmetry is employed to implement an intelligent fuzzy traffic signal control system for complex intersections. This approach suggests that the implementation of reduced fuzzy rules through the reduction method, without compromising the performance of the original fuzzy rule base, constitutes a symmetrical approach. In recent decades, urban and city traffic congestion has become a significant issue because of the time lost as a result of heavy traffic, which negatively affects economic productivity and efficiency and leads to energy loss, and also because of the heavy environmental pollution effect. In addition, traffic congestion prevents an immediate response by the ambulance, police, and fire brigades to urgent events. To mitigate these problems, a three-stage intelligent and flexible fuzzy traffic control system for complex intersections, using a novel hybrid reduction approach was proposed. The three-stage fuzzy traffic control system performs four primary functions. The first stage prioritizes emergency car(s) and identifies the degree of urgency of the traffic conditions in the red-light phase. The second stage guarantees a fair distribution of green-light durations even for periods of extremely unbalanced traffic with long vehicle queues in certain directions and, especially, when heavy traffic is loaded for an extended period in one direction and the short vehicle queues in the conflicting directions require passing in a reasonable time. The third stage adjusts the green-light time to the traffic conditions, to the appearance of one or more emergency car(s), and to the overall waiting times of the other vehicles by using a fuzzy inference engine. The original complete fuzzy rule base set up by listing all possible input combinations was reduced using a novel hybrid reduction algorithm for fuzzy rule bases, which resulted in a significant reduction of the original base, namely, by 72.1%. The proposed novel approach, including the model and the hybrid reduction algorithm, were implemented and simulated using Python 3.9 and SUMO (version 1.14.1). Subsequently, the obtained fuzzy rule system was compared in terms of running time and efficiency with a traffic control system using the original fuzzy rules. The results showed that the reduced fuzzy rule base had better results in terms of the average waiting time, calculated fuel consumption, and CO2 emission. Furthermore, the fuzzy traffic control system with reduced fuzzy rules performed better as it required less execution time and thus lower computational costs. Summarizing the above results, it may be stated that this new approach to intersection traffic light control is a practical solution for managing complex traffic conditions at lower computational costs.

Open Access: Yes

DOI: 10.3390/sym16091177

Estimation of Thermodynamic and Emission Characteristics of a Sustainable Hydrogen-Gasoline Engine Through Simulation

András Lajos Nagy Péter Németh György Marton Barna Hanula

Publication Name: Lecture Notes in Networks and Systems

Publication Date: 2025-01-01

Volume: 1345 LNNS

Issue: Unknown

Page Range: 21-32

Description:

Hydrogen is expected to play a significant role in mobility and transportation as a form of energy source. To assess the effects of hydrogen as a gradual replacement fuel for internal combustion engines, a preliminary 1D thermodynamic simulation was carried out using AVL Boost for 0 vol%, 4 vol% and 8 vol% hydrogen content. Calculations were based on independently published research results, and focused on peak firing temperature (PFT), brake specific fuel consumption (BSFC), nitrous oxide emission (NOx), and carbon monoxide (CO) emission values. Results showed a decrease in BSFC of up to 3 g/kWh and ca. 5 mg/kWh decrease in CO emission with 8 vol% hydrogen, but also highlight an increase of PFT by 14 K, and ca. 0.5 g/kWh additional NOx production at high loads.

Open Access: Yes

DOI: 10.1007/978-3-031-87620-2_3

Molecular dynamics simulation of carbon nanostructures: The C60 buckminsterfullerene

Ibolya Zsoldos István László

Publication Name: Physica Status Solidi B Basic Research

Publication Date: 2012-01-01

Volume: 249

Issue: 12

Page Range: 2616-2619

Description:

Molecular dynamics calculations can reveal the physical and chemical properties of various carbon nanostructures or can help to devise the possible formation pathways. In our days the most well-known carbon nanostructures are the fullerenes, the nanotubes, and the graphene. The fullerenes and nanotubes can be thought of as being formed from graphene sheets, i.e., single layers of carbon atoms arranged in a honeycomb lattice. Usually the nature does not follow the mathematical constructions. Although the first time the C60 and the C70 were produced by laser irradiated graphite, the fullerene formation theories are based on various fragments of carbon chains and networks of pentagonal and hexagonal rings. In the present article various formation pathways for the buckminsterfullerene C60 molecule will be presented. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Open Access: Yes

DOI: 10.1002/pssb.201200125

Laboratory tests on properties of innovative natural thermal insulation material

David Bozsaky Rebeka Ábrahám-Horváth

Publication Name: Pollack Periodica

Publication Date: 2023-07-11

Volume: 18

Issue: 2

Page Range: 125-130

Description:

Nowadays, there is an increasing demand on environmentally friendly materials, so the environmentally conscious architecture and the use of environmentally friendly materials have also become preferred. It is becoming increasingly important to turn from artificial materials to products made from renewable raw materials. The straw quilt, which is considered to be a new, innovative product on the Hungarian construction market, can provide an alternative for this need. The aim of this research was to investigate the material properties and possible uses of straw quilt thermal insulation. Laboratory tests were performed before the product was placed on the market. The results have shown that it has several advantageous properties that can make it competitive in the market of thermal insulation materials.

Open Access: Yes

DOI: 10.1556/606.2022.00735

Characterisation of Hungarian Cikta sheep based on the control region of mtDNA

Petra Zenke Ákos Maróti-Agóts Károly Tempfli Annus Kata Sáfár László Kovács Endre Harmat Levente András Gáspárdy

Publication Name: Magyar Allatorvosok Lapja

Publication Date: 2020-07-01

Volume: 142

Issue: 7

Page Range: 421-428

Description:

Background: The consideration of the high genetic diversity is indispensable on the course of preservation of endangered animal breeds. Objectives: The authors evaluate the genetic background in the Hungarian native Cikta breed by use of mitochondrial DNA (mtDNA) control region (CR) sequence firstly. Their investigation was carried out in order to serve data for the maintenance of maternal lineages. Materials and Methods: The DNA samples were taken from the descendants of the eldest families by use of founder sampling method based on pedigree (n = 69) in 2015. The primers described by Hiendleder et al. (7) were used to amplify the region of interest (AF010406). Results and Discussion: The control region of mtDNA showed polymorphisms at 32 sites. However, the herds shared 24 polymorphic sites, so the maternal background of the Cikta appears to be genetically uniform. The total number of haplotypes were 13, furthermore, most of the samples belonged to the haplog-roup B of sheep. This fact proves the decisively European maternal origin of the Hungarian Cikta. The average number of pairwise differences (k) and the average nucleotide diversity (ro) were 6.863 and 5.95 × 10-3, respectively. The values of the Cikta population were not significant (p < 0.10) neither by the Tajima D-test (0.107) and by Fu's Fs statistics (2.533), meaning that the greatly reduced population size of the breed known from the breed history did not cause genetic drift, it is in genetic equilibrium regarding its ancient families. The genetic information confirmed the origin of the families/flocks known from the breed history. A more intense focusing on the maternal side is motivated also by the fact that the females are present at greater number than the males, respectively they remain in breeding for a longer period of time, so they can at larger extent be the depositaries of realization and maintenance of genetic diversity.

Open Access: Yes

DOI: DOI not available