Periodica Polytechnica (Budapest University of Technology and Economics)
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Verification of Railway Control Systems Using Model Checking and CTL, Explained Through a Case Study
Get PDFSystematic faults can often occur during the development of a system. The later such faults are discovered, the more expensive it can be to correct them. In systems engineering practice, there are many methods and tools to reduce the likelihood of systematic faults. In this paper, we present the application of a formal model–based verification technique – called model checking – to assist railway engineers in designing and verifying the safety-related functionality of railway control systems. The proposed process is part of a specification-verification environment that facilitates the construction of correct, complete, consistent, and verifiable functional specifications during development. The results and experience in model checking are illustrated by a case study of a vehicle detection point, a common component in this domain. The model checking of the case study has been performed in the widely used UPPAAL modeling and simulation framework, which can also verify formal properties and generate a counterexample in case of a property violation. By analyzing the counterexample, the designer can gain insights into the system's behavior and identify potential design flaws or failures. Model checking can be used to achieve a higher quality functional specification that is typically more complete and/or contains fewer faults compared to the traditional development approach
The Relationship Between Loading Frequency and Truck Speed on Asphalt Pavements
Get PDFThe mechanistic-empirical road pavement design methods necessitate knowledge of the dynamic modulus master curve of asphalt mixtures. This requires the designer to accurately define both the load frequency and the temperature of the pavement structure. The parameter of load frequency is of great importance in laboratory fatigue tests. However, it presents a challenge since road structures are loaded in the time domain, not the frequency domain. This complexity has prompted researchers to develop time-frequency conversion methods to estimate the corresponding frequency from the duration of traffic-induced stress or deformation pulses. Recent findings indicate that the time-frequency equivalence factor is considerably lower than previously assumed. In this study, we introduce a new four-parameter empirical RAMBO material model, derived from the Ramberg–Osgood equation, which offers parameters to determine the time-frequency equivalence factor for asphalt mixtures. The relationship between the moving wheel load velocity and the load impulse time is analysed, primarily based on experimental data and computational methods from existing literature. A method for determining the wavelength of the load impulse is proposed. The theoretical correlation indicates that a wheel load travelling at 100 km/h results in a dynamic deformation frequency of 10 Hz. However, for a strain impulse, the same speed corresponds to a much lower frequency of 3–4 Hz. This study offers a refined understanding of the time-frequency equivalence factor, which is of crucial importance for more accurate road pavement design and fatigue testing
Fuzzy Rule-based Comparison of Alternative Jet Fuels
Get PDFIn today's aviation alternative jet fuels play an increasingly important role. Their application incurs new engineering and environmental protection challenges. The key properties of their feasibility of integration are from technological point of view aging behavior and applicability as well as from environmental protection point of view the carbon footprint. During the comparison process experts can evaluate the above characteristics with linguistic variables. The application of linguistic variables always results in some degree of uncertainty – by their subjectivities. Fuzzy calculation methods are used to mathematically describe these uncertainties. The purpose of this study as a pilot project is to gain experience in developing a methodology of a multi-level fuzzy rule-based jet fuel qualification process
Characteristics of Safety Personality
Get PDFFor high-risk organisations, it is essential that employees demonstrate safety-awareness behaviour, as a reflection of their safety personality, to avoid accidents. Several studies confirm that personality is the individual difference that is most associated with the likelihood of an accident occurring; it is therefore necessary to address the identification and expression of the characteristics of safety personality. This paper aims to present a personality questionnaire the authors have created, which was administered to employees of a large Hungarian company in the electricity supply business with altogether 1273 employees obligated to prioritise workplace safety. The final version of the questionnaire contained 59 items. Based on the statistical results, 58.08% of the variance of total variables was explained by 10 factors; the scales of the questionnaire developed are otherwise reliable. The paper also examines the validation of the scales using different psychological measures
A 2024-es év Kosáry Domokos-díjasa: Dr. Mader Béla nyugalmazott könyvtári főigazgató, címzetes egyetemi tanár
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Smelting a Zn – Pb Sulfide Ore with Magnetite and Carbon for the Production of a Silicon Alloy and Extraction of Zinc and Lead into Sublimates
Get PDFThe article presents the results of thermodynamic prediction and electric smelting of Shalkiya sulfide zinc-lead-bearing ore in the presence of magnetite and coke. Using the HSC-6.0 software package, it was found that under equilibrium conditions in the presence of Fe3O4 and carbon, the reduction and formation of gaseous zinc from ZnS (according to ∆G° = 0) occurs at a temperature of 1205.7 °C, and the formation of ferroalloy at the interaction of the sulfide ore with magnetite and carbon begins at 1200 °C. About 58% of silicon is extracted into the ferroalloy at 1800–1900 °C; almost all zinc and 83–88% of lead turns into a gaseous state. Electric smelting of the sulfide ore in the presence of magnetite concentrate and coke makes it possible to obtain the FS45 grade ferrosilicon (42–43% of Si); the silicon extraction degree was 84–88%. At the same time, 97.3% of lead and 99.2% of zinc are extracted into the sublimates. The developed method for processing zinc sulfide ores allows us to increase the degree of raw materials' comprehensive use due to the extraction of not only zinc and lead, but also silicon. The technology can be used to process raw materials containing zinc, lead and silica, such as zinc ore concentration tailings