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Found 6374 publications

Safety Ranking of Railway Crossings in Hungary

Csaba Koren Attila Borsos Miklos Gabor

Publication Name: Transportation Research Procedia

Publication Date: 2016-01-01

Volume: 14

Issue: Unknown

Page Range: 2111-2120

Description:

Regarding traffic safety, railway crossings are crucial points in the rail and road network. In Hungary the safety ranking of railway crossings has been performed since 1993 and the results have been used for selecting unsafe locations and for prioritizing safety measures. Prioritization is based on a complex point system taking into account accident data, traffic volumes and various traffic engineering aspects. Weights of various indicators were based on engineering judgement. Although this method has been renewed a few times, there is a need to update this method involving more thorough statistical methods. The objective of this paper is to calibrate a new model and to compare it with previous models. A sample of about 1700 railway crossings satisfying a few requirements (railway with public service, traffic volume data available) was set up. The first part of the paper describes data collection. Five years (2010-2014) of accident data, AADT (Annual Average Daily Traffic) for rail and road, speed limits and further data (road pavement width, control devices, crossing angle, alignment, number of tracks, sight distances) were gathered. The modeling was conducted in two steps. First, each variable was entered into the model alone to see which ones significantly affect accident frequency. As a next step, two-variable models were built where expected injury accident frequency is predicted by annual daily road traffic and annual daily rail traffic. The sample was also split up into subgroups based on the type of control devices in order to analyze their effect on safety. Models are proposed using the Generalized Linear Modeling approach (GLM) assuming a negative binomial error structure. The results give estimation of the impacts of explanatory factors on the safety of railway crossings. Annual daily road traffic and annual daily train traffic are significant predictors. A number of predictors such as crossing angle, track alignment, number of tracks and sight distances turned out to be not significant. As far as the type of control devices are concerned, as expected coefficients are decreasing, hence safety is increasing in the following order: passive crossings, flashing lights, flashing lights + half barriers. Based on the above results, the complex point system used by practitioners for safety ranking was simplified considerably leaving out variables which turned out to be not significant.

Open Access: Yes

DOI: 10.1016/j.trpro.2016.05.226

Numerical examination of nonlinear oscillators

F. Hajdu

Publication Name: Pollack Periodica

Publication Date: 2018-12-01

Volume: 13

Issue: 3

Page Range: 95-106

Description:

The numerical examination of nonlinear oscillators is presented in this paper. First some methods of nonlinear system modeling are described then the numerical creation of phase-plane, bifurcation diagrams and Poincaré sections are expounded in detail. The next part of the paper is the numerical examination of nonlinear oscillators, like the Duffing-Holmes oscillator and a mechatronic semi-active suspension system. The paper concludes with further development tasks.

Open Access: Yes

DOI: 10.1556/606.2018.13.3.10

Three level modelling of uncertainties in the condition assessment of buildings

Adam Bukovics Istvan A. Harmati Laszlo T. Koczy

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

Publication Date: 2016-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

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

Open Access: Yes

DOI: DOI not available

Spatially aggregated data and variables in empirical analysis and model building for economics

No authors available

Publication Name: CyberGeo

Publication Date: 2004-12-01

Volume: 2004

Issue:

Page Range: Unknown

Description:

A short review of the importance of spatial aggregation problem in general and specially in economics is followed by a typology of spatial analysis and statistical data from spatial aggregation viewpoint. The modifiable areal unit problem is divided into two parts. There are the scale and the zoning system effects, which are illustrated using Hungarian data. Spatial data aggregation creates the need for investigating the connection between the theory and data as well as the micro-macro dualism.

Open Access: No

DOI: DOI not available

Slewing of rubber-sprung wheels with railway vechiles

No authors available

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics, Identification and Anomalies

Publication Date: 2004-12-01

Volume:

Issue:

Page Range: 171-175

Description:

The slewing of railway vehicle's rubber-spring wheel means that the wheel has an elastic and plastic change in angle relative to the wheel frame. This study has the objective to explore the evolution and the causes for these angle changes both in laboratory environment and also during the running of the vehicle.

Open Access: No

DOI: DOI not available

Evaluation of the physical, antioxidant, and organoleptic properties of biscuits fortified with edible flower powders

E. Lakatos Székelyhidi Rita Beatrix Sik Laura Hanna Gál Zsolt Ajtony

Publication Name: Food Science and Nutrition

Publication Date: 2024-05-01

Volume: 12

Issue: 5

Page Range: 3265-3272

Description:

Foods enriched with plants have gradually become an area of increasing research interest because plant ingredients may offer several positive effects on human health and the body. The aim of our study was to develop biscuits fortified with three different types of edible flowers (marigold, lavender, and rose) and examine their physical and antioxidant characteristics, as well as consumer acceptability. The antioxidant properties and characterization of biscuits highlighted that edible flowers may cause increased total polyphenol and total flavonoid yields, as well as DPPH radical scavenging activities. Concerning biscuits fortified with rose petals, the total monomer anthocyanin content was also raised. In addition, the results showed that the antioxidant properties of biscuits increased with increasing concentration (from 2.5% to 5.0%) of edible flowers. Despite this, the consumer acceptability results clearly showed that the addition of marigold and lavender at a concentration of 5.0% caused significantly decreased overall acceptance. We found that the fortification step may increase the spread ratio, which is an important quality attribute of biscuits. We found slight variations in the diameter, thickness, and baking loss parameters of fortified biscuits compared to the control. All in all, the best results were obtained when the biscuits were fortified with rose petals at a concentration of 5%.

Open Access: Yes

DOI: 10.1002/fsn3.3993

Logic testing of CMOS structures

No authors available

Publication Name: ICCC 2004 - Second IEEE International Conference on Computational Cybernetics, Proceedings

Publication Date: 2004-12-01

Volume:

Issue:

Page Range: 59-64

Description:

The paper presents a test calculation principle which serves for producing tests of switch-level logic faults in CMOS digital circuits. The considered fault model includes stuck-at-0/1 logic faults on the connecting lines, as well as switch faults in the transistors. Both single and multiple faults are included. The transistor faults manifest themselves in stuck open (open circuit) and stuck short (short circuit) behavior. In this paper only combinational logic circuits are taken into consideration. The calculation principle is comparatively simple. It is based only on successive line-value justification, and it yields an opportunity to be realized by an efficient computer program. ©2004 IEEE.

Open Access: No

DOI: DOI not available

Initial value selection of the model parameters in the curve fitting phase of the dynamic SPECT imaging

Balázs Benyó Péter Somogyi Gábor Hesz Katalin Kovács Zsófia Barna Ákos Szlávecz

Publication Name: IFAC Papersonline

Publication Date: 2018-01-01

Volume: 51

Issue: 27

Page Range: 241-246

Description:

The dynamic SPECT (Single Photon Emission Computed Tomography) reconstruction algorithm developed in our prior work reconstructs the parameters of the time activity curve for each image voxel directly from the projection images. In each iterations of the SPECT reconstruction beyond the static 3D MLEM (Maximum Likelihood Expectation Maximization) step, the algorithm performs a fitting process for each voxel in order to estimate the parameters describing the function of the examined organ considering that the time frames are not independent from each other. In real cases the fitted curve is nonlinear function of these parameters, it is usually described as the sum of exponential functions. In order to estimate the parameters properly, an iterative root-finding method is applied. In the current study the Newton-Raphson method is used. The selection of a proper initial value for the root-finding method is critical in order to achieve convergence of the fitting process. If the initial guess is not appropriate, the root-finding algorithm can diverge or converge to an inappropriate parameter set that can result in unacceptable reconstructed parameters. This affects then the subsequent MLEM iterations, also neighboring voxels and breaks the reconstruction. In this work we investigated different methods to calculate the initial values of the fitting process and evaluated the reconstructed parameter set of the dynamic SPECT reconstruction algorithm. Three different methods are investigated, one that uses the fitted parameters of the previous MLEM iteration, one that is based on the sum of the geometrical series of the exponentials and one that calculates the best guess using both methods. The three methods were compared by benchmark reconstruction cases using a mathematical phantom. In each reconstruction different initial value selection method was applied then the time activity curves of the voxels belonging to the same tissue were statistically evaluated using the reconstructed parameters. In the study no significant differences were found in the mean value of the reconstructed parameters. The standard deviation of the parameters was similar between the two simple approaches, however, the combination of the methods resulted in better statistical performance.

Open Access: Yes

DOI: 10.1016/j.ifacol.2018.11.635

Examining the accuracy and the precision of PDEs for FPGA computations

Zoltán Nagy András Kiss Árpád Csík Péter Szolgay

Publication Name: International Workshop on Cellular Nanoscale Networks and their Applications

Publication Date: 2012-12-13

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

There are a large number of problems which can be accelerated by using architectures on Field Programmable Gate Arrays (FPGA). However sometimes the complexity of a problem does not allow to map it onto a specific FPGA. In that case analysis of precision of the arithmetic unit which may solve the computational problem can be a good attempt to fit the architecture and to accelerate its computation. Numerical algorithm can be implemented using fixed-point or floating point arithmetic (or mixed (both)) with different precision. The aim of the article is not to optimize the numerical algorithm but to find a smaller arithmetic unit precision, which results enough accuracy and fits to smaller FPGA-s. In the paper, one particular problem type is investigated, namely the accuracy of the solution of a simple Partial Differential Equation (PDE). The accuracy measurement is done on an FPGA with different bit width. The solution of the advection equation is analyzed using first and second order discretization methods. As a result we managed to find an optimal bit width for the solution on a specific FPGA. © 2012 IEEE.

Open Access: Yes

DOI: 10.1109/CNNA.2012.6331439