Periodica Polytechnica (Budapest University of Technology and Economics)
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Development and Characterization of Chitin-based Hydrogel Nanocomposites from Animal Shells for Sustainable Agriculture
Full text linkThis paper presents a report on the design and performance testing of a nano-chitin-source-based hydrogel (Portunus pelagicus crab) shell-derived nano-hydrogel in support of sustainable agricultural uses in terms of its potential to be used in water retention and urea release. Using a multi-step acid hydrolysis method, nano-chitin could be extracted and introduced into a NaOH/urea aqueous solution whereby a hydrogel was formed. The prepared hydrogel was expected to minimize the loss of nutrients and increase the moisture holding capacity of soil in arid and semi-arid environments. The Fourier transform infra red spectra proved the existence of typical N-H and amide functional groups at 3257 cm−1 and 1631 cm−1, respectively. In X-ray diffractograms crystalline peaks were observed at 9.35° and 23.2° which revealed that nano-chitin is partially de-crystallized after hydrogel formation. The scanning electon microscopic images exhibited about 55.5 nm wide semi-crystalline nanofibrilsand nanopores on the surface of the fibres favouring high water-retention capacity and nutrient loading capacity. Application of soil trials showed 50% higher water holding capacity and 88% urea release, which results in long-lasting nutrient. In a plant growth experiment using Vigna radiata, it was observed that plant seed germination and their initial growth are enhanced and therefore the gels are agronomically viable. Soil analysis of the soil before and after hydrogel addition showed that there was an improvement in the soil ammoniacal nitrogen and moisture content
Comparative Assessment of Pore Structure and Water Retention in Concrete Using MIP, CT, SEM, and Dewpoint Techniques
Full text linkUnderstanding water retention and pore structure in concrete is essential for modeling unsaturated flow and assessing long-term durability, particularly in containment and deep foundation structures. This study investigates two concrete mixtures with different water-to-cement (w/c) ratios (0.40 and 0.50) using a multi-method approach. Water retention curves (WRCs) were measured with a chilled-mirror dewpoint potentiometer and fitted using the Fredlund–Xing model. Pore structures were analyzed via mercury intrusion porosimetry (MIP), X-ray computed tomography (CT), and scanning electron microscopy (SEM). Results show that the mixture with the lower w/c ratio exhibits a higher proportion of fine pores, while the higher w/c ratio leads to a broader pore size distribution and a flatter WRC. MIP-based WRC estimations provided a rough approximation but consistently underestimated measured retention values. CT and SEM revealed distinct pore size domains, with pore size distributions fitting better to a lognormal model than to a Weibull distribution. Although each technique offers only partial insight, their combined application allows for a more comprehensive understanding of concrete's pore network and its effect on hydraulic behavior. The findings highlight both the potential and the limitations of using indirect pore structure data to estimate water retention characteristics in cementitious materials
Acidic Deep Eutectic Solvents as Green and Reusable Catalyst for Emulsifier Synthesis
Full text linkEmulsifiers known as mono- and diglycerides (MDG) are produced when fatty acids are esterified with glycerol (glycerolysis of fatty acids) with the use of an acid catalyst. This work is the first to use non-toxic deep eutectic solvents (DES) as a green catalyst for palmitic acid glycerolysis. The effect of various reaction temperatures and catalyst loadings on the catalyst activity of acidic DES (mixtures of betaine hydrochloride and citric/propionic acid), and reusability test of the catalyst were studied. The reaction takes place at a palmitic acid to glycerol molar ratio of 1:6 at a stirring speed of 300 rpm, reaction temperatures of 120-180 °C, and catalyst loadings of 1-5 wt.% (based on palmitic acid). Conversion of palmitic acid tends to increase with the increasing in reaction temperature and catalyst loading. The highest reaction conversion reaching 90.3% and produce the monoglycerides emulsifier as much as 72.8%. In addition, this catalyst is also very effective for reuse
Screen-printed Potentiometric Selective Electrode Based on an Ammonium Quaternary Salt for Nitrate Detection
Full text linkIn this study, a screen-printed electrode for nitrate ions was evaluated with a selective membrane based on tetradecyl ammonium nitrate as the ionophore, o-nitrophenyl octyl ether as the plasticizer, and polyvinyl chloride as the polymeric matrix. The electrodes were printed on polyethylene terephthalate sheets using a screen-printing frame with the electrode template. Then, the selective membrane was deposited by drop casting. The principal analytical parameters were determined by the method of additions recommended by IUPAC. The membrane showed a good linear response range of 5.38 × 10−6 to 1 × 10−2 mol/L, being Nernstian according to the slope of −57.13 mV/dec (theoretical slope: −59.16 mV/dec), with a practical detection limit of 2.96 × 10−6 mol/L and a lower limit of linear response of 5.38 × 10−6 mol/L. The potentiometric selectivity coefficients for Cl−, Br−, I−, SO42−, and IO3− ions were determined using the mixed solutions method. The Br− ion was found to be the most relevant interferent. The electrode showed a fast stable response (20 s), as well as the possibility of use in a wide pH range (3–12) without compromising the potentiometric response
Strength Properties and Evaluation Method of Composite Modified Carbonaceous Mudstone Soil-rock Mixtures
Full text linkThe application of carbonaceous mudstone soil-stone mixtures (CM-SRM) in embankment engineering is limited due to its poor mechanical properties. This study aims to enhance the strength properties of CM-SRM by modifying it with guar gum, fly ash and red clay. Unconfined compressive strength (UCS) tests and triaxial compression tests were carried out using orthogonal design methods to systematically analyze the mechanical properties and modification mechanisms of modified CM-SRM. The results indicated that the modified CM-SRM exhibited failure modes such as single-shear, single-shear-bulging, double-shear, and double-shear-bulging, with fly ash and guar gum dosages significantly affecting both failure modes. Unconfined compressive strength and cohesion increased post-modification, with minor changes in friction angle. Orthogonal analysis reveals that guar gum dosage significantly effects on UCS and shear strength indexes, whereas the effect of fly ash is comparatively weaker. Based on the test results, a shear strength evaluation method based on linear and nonlinear models is proposed. The study shows that the composite modification mechanisms of red clay, fly ash, and guar gum on CM-SRM mainly includes bonding and filling effects, cation exchange, and gel aggregation. The suggested dosage combination is 10% red clay, 5% fly ash, and 4% guar gum
Forecasting the Number of Road Accidents in Poland and Hungary Using Neural Networks
Full text linkThe incidence of road accidents in Poland and Hungary has been on a downward trend annually, a pattern that is also evident globally. Although the recent pandemic has impacted these statistics, the total remains alarmingly high. Consequently, it is crucial to implement all possible strategies to reduce this figure further. This article aims to project future road accidents in Poland and Hungary. To achieve this, we analysed yearly statistics regarding road accidents in the two nations. Utilising data from the Polish Police and the Hungarian Central Statistical Office, we made forecasts from 2024 to 2030. Several selected neural network models were employed for this predictive analysis. The findings indicate that we can anticipate a continued stabilisation in the number of road accidents. Several factors, including the rising number of vehicles on the roads and the development of new highways, influence this trend. Additionally, the chosen sizes for the sample sets (learning, testing, and validation) play a significant role in the results obtained
Enhanced Fuzzy-Power Control for WECS based on Variable Wind Speed-Driven DFIG Using SVM Strategy under Sub- and Super-synchronous Operating Modes
Full text linkThis paper presents an efficient stator power control algorithm for a grid-connection wind turbine system based on a doubly fed induction generator (DFIG) operating under variable wind speed conditions. The proposed approach focuses on controlling the stator power of the DFIG under varying operating conditions. In order to extract maximize wind power extraction, the stator-side power factor is maintained at unity through maximum power point tracking (MPPT). An advanced fuzzy-type controller, known as Type-2 Fuzzy logic control (T2-FLC), is proposed to regulate the rotor's direct and quadrature currents. Simulation results obtained in the MATLAB/Simulink environment demonstrate that the T2-FLC controller offers robust performance, superior dynamic response, and enhanced operational efficiency for the wind energy and drive applications in steady-states conditions
Multi-objective Site Selection and Capacity Optimization of Distributed PV Energy Storage in Smart Distribution Network Based on Non-cooperative Game
Full text linkThe disordered integration of high-penetration distributed photovoltaics (DPVs) into smart distribution networks has caused critical challenges including transformer reverse overloading and degraded power quality. Strategically deploying grid-level energy storage systems (ESSs) presents an effective solution to address these issues while enhancing operational efficiency and power quality. This paper proposes a non-cooperative game theory-driven optimal siting and sizing method for DPVs and ESSs in smart distribution networks. A tri-objective optimization model is formulated to mitigate grid vulnerability, reduce power losses, and minimize life-cycle carbon emissions of PV generation. To resolve conflicting interests among multiple stakeholders (DPV owners, ESS operators, and grid companies), a non-cooperative game framework with equilibrium strategies is established. An improved multi-objective particle swarm optimization (IMOPSO) algorithm is developed to solve the Nash equilibrium point that maximizes benefits for all participants. Case studies on IEEE 33 bus and IEEE-69 bus distribution systems demonstrate that the proposed method achieves: 2.43% reduction in grid vulnerability index, 4.29% decrease in network losses, and 44.44% reduction in PV life-cycle carbon emissions – all while maintaining voltage quality requirements and realizing Pareto-optimal allocation solutions for multi-stakeholder interests
Current trends in library and information science in the light of PhD research and studies – 1.: Interview with Etele Szüts
No full textThe editorial team of CELISR conducted a short interview with recent graduates of the Library and Information Science doctoral program at the ELTE Doctoral School of Literary Studies, in order to provide the journal’s readers with an insight into the current and future scientific activities of researchers, and to give an idea of the current research trends in thefield. The following article contains a brief overview of the PhD research conducted by Etele Szüts, Director of the Hungarian Library Institute, with background and future prospects
H-index és kutatói értékelés: Egy lehetséges, átfogó, szerzői szintű értékelési mutató komponensei (Szemletanulmány)
No full textNorouzi, A., Parsaei-Mohammadi, P., Zare-Farashbandi, F., Zare-Farashbandi,E., Geraei, E. (2024) H-index and research evaluation: A suggested set of components for developing a comprehensive author-level index, Journal of Information Science. https://doi.org/10.1177/0165551524129376