Periodica Polytechnica (Budapest University of Technology and Economics)
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A 2025-ös év Kosáry Domokos-díjasa: Prof. Dr. Papp Klára történész, professor emeritus, az MTA doktora
No full text2025-ben a Kosáry Kuratórium javaslatára az Egyetem Szenátusa a Kosáry Domokos-díjat Papp Klára történész, a Debreceni Egyetem professor emeritusa, egykori dékánja, a Gróf Tisza István Debreceni Egyetemért Alapítvány professzora, az MTA doktora részére adományozta a hazai és határon túli gyűjteményekben őrzött források feltárása, közzététele, a társadalom- és agrártörténeti kutatások területén végzett kiemelkedő munkássága, valamint egyetemi oktatói és tudományszervező tevékenysége elismeréseként
Estimation of the Constitutive Relationship between Impact Resistance and Compressive Strength in Sandstones
Full text linkA series of experiments were performed to investigate the relation between the impact resistance and the compressive strength of sedimentary rocks. The experiments were conducted by the use of Charpy hammer. As a result of these series of experiments an analytical relation was elaborated between the impact resistance and the compressive strength of sedimentary rocks. An envelope domain is presented as an upper and lower bound for this relation, respectively. In the case of the samples, regardless of temperature and saturation states, the impact work values fell within the range bounded by these limit lines (two straight lines). This makes it possible to obtain an estimated strength value by the help of the tests performed in this way only by determining the density and impact work. Measurements performed at different temperatures and saturation states showed that the temperature of the sample at temperatures between −12 °C and 20 °C only minimally affects the result. The water saturation of the sample has a much greater effect on the impact resistance
Determining Local User Preferences in the Adaptive Reuse of Historical Buildings as Social and Cultural Spaces: The Case of the Erzurum Protestant Boys' School
Full text linkOne of the reasons for the disappearance of architectural heritage, which constitutes the collective memory of societies, is the gradual loss of functionality over time. Historical buildings that lack function and are closed off to users are inevitably condemned to deteriorate and fall into ruin, ultimately disappearing along with all traces of the past. The adaptive reuse of buildings with historical value is a comprehensive process aimed at preserving their significance while adapting them for contemporary use and transmitting them to future generations. Choosing the most appropriate function from among the alternatives proposed for the reuse of historical buildings requires considering multiple factors. In adaptive reuse, which is regarded as a conservation approach, architectural characteristics, social and cultural values, environmental factors, and user opinions should all be considered when assigning new functions to historical structures. Although these factors are generally considered in adaptive reuse projects, user opinions often remain in the background. Therefore, adopting a participatory approach that integrates user perspectives into the reuse process would be a more accurate and effective strategy. In this study, the aim is to determine local user opinions and preferences within the adaptive reuse process of historical buildings, with a specific focus on the Protestant Boys' School located in Erzurum. As a method, a five-point Likert scale questionnaire was administered to 100 local users. Based on the survey results, a new social and cultural function is proposed for the Protestant Boys' School, which considers the desires and preferences of the local community
Lamé Curve-based Spiral Tool Path Generation for Rough Milling
Full text linkAutomatic tool path generation for milling has been a subject of research for decades. The primary challenge in this area lies in simultaneously satisfying both geometric and technological constraints. Although various methods have been developed for spiral trajectory generation to meet these strict criteria, the potential of Lamé curves (also known as superellipses) has remained unexplored. This paper aims to address this gap by introducing a new algorithm that parametrises Lamé curves and transforms them into spirals using polar coordinate functions. The novel method generates a continuous tool path that smoothly fills the region between two closed boundaries without interrupting the cutting process. The algorithm was validated through case studies involving various pocket-like and island-like geometries. For the comparative analysis, two widely used strategies were selected as benchmarks: the traditional contour-parallel strategy and the advanced adaptive milling strategy. The simulation and cutting experiments conducted to analyse cutter engagement, tool load, and machining time demonstrated that the Lamé-based spiral paths achieved 1–44% improvements in machining time and 3–17% reductions in peak cutting force. These improvements are attributed to the smooth path curvature and the stable cutter engagement along the path, which enables effective tool load control. Although the strategy has certain geometric limitations, the results indicate that Lamé-based spirals offer a promising alternative for improving productivity and tool life in rough milling
Unanswered Questions on the Registration of Electric Scooters from the Perspective of the Automotive Industry and the Law
Full text linkThe rise of micromobility has brought increased use of low-speed transport devices such as electric scooters, Segways, and e-bikes. Despite their global popularity, the legal status of electric scooters remains unclear. A key regulatory question is whether e-scooters should be classified as vehicles. While some European countries consider them vehicles, others place them under existing categories like mopeds or bicycles, or even classify them as pedestrian devices. This classification affects all subsequent regulatory considerations. This study focuses on the registration of electric scooters, a topic with limited information despite its potential to address legal issues like theft and liability. The analysis examines regulatory frameworks in select European countries, compares them with practices in certain U.S. states, and highlights successful approaches in Asia, notably Singapore. The findings emphasize the role of vehicle databases in legal problem-solving and evaluate the effectiveness of existing systems. It may also be an incentive for the legislator to consider whether appropriate solutions can be found for the registration of other means of transport (e.g., bicycles, mopeds) and whether the adoption of these options could be appropriate for electric scooters
Failure Analysis of Mortar Specimens with a Hexagonal Honeycomb Panel during Fatigue Load
Full text linkIt has been published in recent research studies that several mechanical properties of mortar reinforced with suitably spatial shaped plastic elements can be improved. Thus, a hexagonal geometric shape was chosen due to its high rigidity for this study. Stress distribution at a bi-material interface between a polymer part reinforcing a mortar specimen and the rest of the mortar part has been investigated to explain fatigue fracture behavior of rectangular specimens tested. A three-point-bending (3PB) test was simulated via a finite element method (FEM) considering several simplifications, and various heights of the polymer reinforcement were modeled to investigate its influence on stress redistribution. For comparison, a pure mortar specimen without any plastic elements was considered the reference. The numerical results obtained are discussed and compared to the experimental ones. Within the experimental campaign, bulk density, static properties and fatigue characteristics were tested, analyzed and discussed. Improvements in flexural strength were observed when the plastic panel was used as reinforcement, which agrees with other scientific works. Directions for future research were identified
Application of Response Surface Methodology for the Adsorptive Removal of Chromium Using Modified Cellulose
Full text linkIn this study, a Modified Cellulose Polymer (MCP) was synthesized through selective oxidation in a cellulose polymer utilizing sodium periodate (NaIO4), which introduces benzothiazole as a functional attachment without disrupting the cellulose backbone. Response surface methodology was employed for the adsorption of chromium on MCP, and the process parameters were optimized. Three critical process parameters, particle size (398-498 nm), pH (5-7), and adsorbent dose (20-30 mg/L), were optimized to obtain the optimal response of chromium adsorption using the statistical Box–Behnken design. The experimental data obtained were analyzed using analysis of variance (ANOVA) and fitted to a second-order polynomial equation using multiple regression analysis. Numerical optimization, utilizing the desirability function, was employed to determine the optimal conditions for maximum chromium ion removal. A two-level fractional factorial model and the Box-Behnken matrix were employed to optimize the batch adsorption parameters for the adsorption of chromium from aqueous solutions by modified cellulose. Under the optimized conditions of pH 6.04 ± 0.05, particle size 485.49 ± 2 nm, and adsorbent dose of 24.14 ± 0.5 mg/L, MCP demonstrated the maximum chromium adsorption capacity with a desirability score of 0.805. The batch adsorption experiments confirmed the efficacy of MCP in removing chromium from aqueous solutions, as evidenced by the close alignment between the predicted adsorption capacity (134.53 ± 1.8 mg/g) and the experimental result (132.52 ± 2,1 mg/g). These findings highlight the potential of MCP as an effective and environmentally friendly adsorbent for industrial water-treatment applications
Closed-form Solutions for Lateral Displacement of Single-bay Coupled Shear Walls Using a Subsystem-based Three-field CTB Beam
Full text linkLocal shear deformation and axial extensibility of walls have recently been recognized as critical, yet previously overlooked, sources of error in predicting the lateral displacement of coupled shear walls. Existing analytical models often face limited practical application due to solution complexity and insufficient physical clarity. Using a generalized continuous model, this paper proposes a simple, exact, closed-form analytical formulation based on an independent subsystem approach, enabling fast and accurate estimation of lateral displacements. The generalized continuous model couples, in parallel, an extensible Timoshenko beam and a shear beam, thereby capturing both shear deformation and axial extensibility. The total lateral displacement is expressed as a linear combination of three independent subsystems: bending, shear, and bending–shear coupling. Closed-form solutions are derived for each subsystem under uniform, triangular, and top-concentrated loading. The displacement components—bending, shear, and interaction—are physically interpreted, with the interaction term arising exclusively from the coupling subsystem. Numerical examples illustrate the physical meaning of each component, while a parametric analysis establishes applicability limits, showing a maximum safe-side error of +7.30%, compared to the −56.04% unsafe-side error of the classical solution. The proposed formulation ensures structural safety, maintains analytical simplicity, and is well-suited for practical engineering design
Elastic-plastic Analysis of Bonded Composite Repair in Cracked Welded Structures
Full text linkThe present paper employs the 3D finite element method to investigate the elastic-plastic behavior of repaired cracks in welded structures reinforced with bonded composite patches. The analysis is based on the J-integral, an important parameter for crack tip characterization. Two different patch configurations are considered: single and double symmetric patches. The effect of patch thickness, adhesive properties and the mechanical behavior of weld-metal on the J-integral variation are systematically evaluated. The results revealed that the double symmetric patch configuration excels over a single patch in terms of improving repair efficiency. Additionally, it is found that the mechanical behavior of weld-metal plays a crucial role in determining the performance of the reinforced welded structures
Smart Grid Ready Controls' Effect of Heat Pumps on Operational Carbon Emissions
Full text linkThis study investigates the impact of Smart Grid Ready (SGR) control strategies on reducing the operational carbon emissions of air-to-water heat pumps in residential buildings across Germany, Denmark, and France. Using dynamic energy simulations that incorporate both real-time and predictive grid carbon intensity data, the research compares perfect and data-informed demand response approaches for heat pump operation. Results demonstrate that SGR controls, especially with perfect day-ahead forecasting, can shift heat pump operation to periods of lower grid carbon intensity, leading to reductions in the carbon intensity of electricity consumed by HVAC systems of up to 3%, with the most substantial gains observed in Germany (a decrease of 14 gCO2/kWh in 2022). However, absolute reductions in operational carbon emissions remain less than 2.6%, partly due to slight increases in electricity demand caused by higher storage temperatures during load shifting. Furthermore, the study highlights that optimizing PV system sizing, based on self-production and grid liability metrics, is crucial for effective renewable energy integration, which yields a lower PV capacity than traditional Net Zero Energy Building (NZEB) methodologies suggest. These findings highlight the importance of advanced, context-sensitive control algorithms and integrated design for achieving meaningful carbon mitigation in grid-interactive, renewable-powered residential buildings