Periodica Polytechnica (Budapest University of Technology and Economics)
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Finite Element Modeling with Ultrasonic Pulse Velocity for Visualising Rock Deformations
Full text linkRocks serve as critical structural components and aggregates in concrete mixtures for civil infrastructure. A persistent challenge in construction has been the insufficient understanding of the quality of raw materials employed. Non-destructive testing techniques, such as ultrasonic pulse velocity, enable detailed characterization of the physical and mechanical properties of rocks. However, these methods are not consistently applied or accurately interpreted to evaluate rock quality. This study proposes an innovative methodology that integrates ultrasonic pulse velocity to estimate the dynamic modulus of elasticity and assess rock deformation using a finite element model. Ten rock samples, comprising volcanic and crushed rocks, were subjected to analytical techniques. Key parameters, including density, uniaxial compressive strength, and ultrasonic pulse velocity, were measured. Furthermore, advanced methods such as high-resolution scanning electron microscopy and X-ray fluorescence spectroscopy were employed to investigate surface morphology and elemental chemical composition. The findings indicate that crushed materials exhibit superior physical and mechanical properties compared to volcanic stones. The proposed model enables the classification of quarries based on ultrasonic pulse velocity as a physical property and corresponding mechanical properties. The data collected were utilized to calibrate the model for determining the deformability of the rock samples. Numerical analysis revealed strong correlations between ultrasonic pulse velocity and deformation, with a correlation coefficient (R²) of 0.87 for horizontal deformation and 0.97 for vertical deformation. These results demonstrate that the novel methodology presented in this study provides valuable insights for prioritizing the use of regional quarry materials, thereby supporting the structural integrity of construction projects
Corrigendum
Full text linkGyörgy Gajári, Lajos Kisgyörgy, Sándor Ádány, András Mahler, János Lógó "A Visco-hypoplastic Constitutive Model for Rolled Asphalt", 65(3), pp. 798–809, 2021. (in this issue)https://doi.org/10.3311/PPci.17515When the above article was first published online, Fig. 5 was incomplete. The explicit citation to Fellin (2002) [1] was missing. The correct version of Fig. 5 is published here
Evaluating the Environmental Impact for a Small Apartment: Using Traditional Wall-mounted Gas Convector vs. Transitioning to Heat Pump
Full text linkThe replacement of old, fossil fuel-based heating systems is of paramount importance. In households of the European Union, space heating accounts for the largest share of final energy consumption, making the method of heat production critical. Various studies estimate that approximately 120 million buildings in the EU require some form of refurbishment, either passive or active, to comply with the latest energy performance directives. Existing regulations focus primarily on efficiency and aim to reduce heat losses, suggesting the replacement of outdated systems and the upgrading of building envelopes. However, they rarely consider the environmental impact of other life cycle stages except use stage of the newly installed building elements. This situation may escalate to the point where considering the whole life cycle of an improvement or replacement is no longer justified solely by emissions and energy use. The Energy Performance of Buildings Directive, and its localized regulations in Hungary impose criteria that require the renovation of existing buildings, often making compliance achievable only through heating system replacements. Hence, this study investigates the background of heating system changes in a small traditional flat, assessing their benefits in terms of emissions and energy use over the full life cycle
Anti-interference Technology of Intelligent Communication Based on Improved GA and GWO
Full text linkChaotic mapping enhances anti-interference in frequency hopping communication by optimizing genetic algorithm population initialization. An intelligent decision engine model employs optimized grey wolf parameters and individual exchange mechanisms, enhancing grey wolf optimization convergence speed for constructing frequency hopping patterns. Experimental data reveals the improved genetic algorithm's efficiency with average run times of 0.312s and 0.057s for adaptive and enhanced versions, respectively. Achieving optimal solution convergence rates of 99.3% and 100%, the enhanced algorithm boosts decision-making accuracy and efficiency. The intelligent decision engine exhibits strong anti-interference capabilities, suitable for −2dB to 10dB signal-to-interference ratios with error rates below 10−6. The improved grey wolf optimization algorithm surpasses traditional approaches, yielding a 9.5% profit increment with a total value of 2310. This technology showcases adept learning and anti-interference capabilities, offering innovative solutions for communication systems and anti-interference technology advancements
A Zágrábi Nemzeti és Egyetemi Könyvtár magyar nyelvű gyűjteménye
No full textThe National Library of Zagreb is the second largest library in Croatia. It is also a university library, and as such, it also meets the needs of the students of the Hungarian Department in Zagreb. The Hungarian Department Library began to flourish with the move to the new building, and today the collection comprises some 5,000 titles and 860 periodicals, which is currently being expanded.A Zágrábi Nemzeti Könyvtár Horvátország második legnagyobb könyvtára. Az intézmény egyben egyetemi Könyvtár is, ebben a minőségében igyekszik kielégíteni a zágrábi Magyar Tanszék hallgatóinak igényeit is. A magyar tanszéki könyvtár felvirágozása az új épületbe való költözéssel kezdődött, a gyűjtemény ma kb. 5000 címszót és 860 folyóiratot foglal magában, gyarapítása jelenleg is aktívan zajlik
A tudománymetriai és bibliometriai kutatások trendjei és fejlődése a Scopus adatbázis alapján (szemle)
No full textSynergistic Effects of Biomass-polyethylene Co-gasification: A Simulation Approach
Full text linkA parametric study on syngas production from the co-gasification of biomass and plastic waste using oxygen as the gasifying agent was conducted using an Aspen Plus simulation. The study examined the effect of plastic content and its synergistic interaction with biomass. Key operating parameters, including equivalence ratio (ER) and blend ratios were varied to assess their impact on hydrogen and carbon monoxide concentrations, the H2/CO ratio, lower heating value (LHV), gas yield (GY), and cold gas efficiency (CGE). Increasing plastic content enhanced H2 concentration but reduced CO levels. At ER of 0.1, a 75% polyethylene and 25% biomass mixture achieved 56% H2 while pure biomass yielded 56.4% CO. The highest CO content in the blended feedstock (54.2%) was obtained at ER of 0.22 with 25% PE and 75% biomass. The H2/CO ratio of 2, ideal for synthetic fuel applications, was achieved at an ER value below 0.4 for 50% and 75% PE mixtures. While the co-gasification improved H2 production, LHV showed no enhancement, indicating no additional energy benefits from co-gasification. However, the GY exhibited synergy, as co-gasification produced more syngas as ER increased, CGE improved due to synergy, particularly at ER values below 0.4 demonstrating enhanced feedstock conversion efficiency. These findings suggest that co-gasification enhances syngas production and overall quality, making it a highly viable process for improving the efficiency of waste-to-energy technologies. In addition, biomass-polyethylene co-gasification shows potential in improving syngas quality, addressing challenges like low H2/CO ratios and low LHV, which are common issues in conventional biomass gasification
Optimizing Semiconductor-insulator-semiconductor Heterojunction Engineering Performance in a Novel High-efficiency Solar Cell Structure
Full text linkIn this study, we introduce and optimize a novel semiconductor-insulator-semiconductor (SIS) solar cell using SCAPS-1D simulations. The Pt/Si/TiO2/ZnSe/ fluorine-doped tin oxide (FTO), structure employs Pt and FTO as back/front contacts. TiO2 serves as a critical insulating layer between p-Si and n-ZnSe, enhancing electrical isolation while boosting stability and efficiency through reduced recombination and improved charge transport. Results demonstrate TiO2 as an insulating material significantly improves the fill factor (FF) and power conversion efficiency (PCE) of the device, compared to conventional structures. Key optimized parameters include: Si 1300 nm, ZnSe 100 nm, and TiO2 insulating layer to 10 nm; defect densities of 1015 cm−3 for both Si and ZnSe, and 1012 cm−3 for the interfaces. This optimized cell demonstrates the following performance results: a VOC of 0.84 V, a JSC of 42.09 mA cm−2, an FF of 86.42%, and a PCE of 30.65%. These results were achieved under standard test conditions (AM1.5G, temperature of 300 K). Our simulations focus on enhancing electrical parameters, particularly efficiency. This study will provide valuable parameters for any future experimental work on SIS solar cells
An Automated Method to Quickly Predict the Settlements of Embankments during Construction
Full text linkIn the process of embankment construction, the most significant point is the construction quality control, especially the settlement control. In order to predict the embankment settlement in the construction process quickly and conveniently, the automated modeling method is studied in this paper. A parametric model replicating the embankment building process was created using ABAQUS's built-in secondary development functionality. The model can consider multiple influencing factors to explore their effects on embankment settlement fully. The sensitivities demonstrated by each parameter were then evaluated to assess their effect on the total settlement. Based on these results, the SASLEF V1.0 program was created and granted software copyright certification. The developed software enables rapid analysis of the embankment layered filling process. The effectiveness of the software was verified by engineering cases. The study can provide a meaningful reference for embankment construction
Simple Model of Soil-structure Interaction in Horizontal Motion Taking into Account the Nonlinearity of the Soil
Full text linkSoil structure interaction is often modeled by lumped parameter models, which consist of connected springs, masses, and dashpots. It was shown that this model – even for the case of elastic behavior – can be rather inaccurate since radiation damping is not properly represented. Pap and her coauthor suggested a simple model that overcomes this problem: a simple infinitely long bar on an elastic foundation connected parallelly to a mass-spring system. Since soil nonlinearity can affect the response considerably, even in the case of moderate seismicity, Pap’s model is extended in this paper for nonlinear soil behavior. As a result, the 3D nonlinear soil can be replaced by a simple beam resting on a foundation and connected parallelly to a mass-spring system. In addition to the three elastic properties, the level of plastification must be prescribed. This model is recommended for the practical modeling of soil-structure interaction when the nonlinearity of the soil is significant