Periodica Polytechnica (Budapest University of Technology and Economics)
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Effect of Friction Stir Welding on Mechanical Properties and Formability of Aluminum Alloy-AA1100
Get PDFThis study investigates the influence of friction stir welding (FSW) on the mechanical properties and formability of thin aluminum alloy sheets for automotive applications. The feasibility of a novel technique, pinless FSW, for joining aluminum sheets was demonstrated. Defect-free welds were successfully achieved using parameter sets R1 (450 rpm, 80 mm/min, 8 mm), R4 (560 rpm, 160 mm/min, 8 mm), and R7 (710 rpm, 250 mm/min, 8 mm). The welded region exhibited an outward material flow due to the stirring action of the FSW tool. Microhardness measurements were conducted in the transverse direction of the weld and along the depth from the top to the bottom at the weld center. Hardness values exhibited variation from the weld zone centerline to the heat-affected zone (HAZ). Lower hardness values were observed at the center of the weld zone, whereas higher hardness values were recorded in the HAZ. The transverse and longitudinal tensile properties of the welds were evaluated at room temperature. The tensile tests revealed that the welded samples failed outside the weld region. To assess the ductility of the FSW welded samples, formability tests were performed, indicating an increase in ductility within the welded area
„A jövő könyvtára” : magyar könyvtárosok nemzetközi együttműködése szakmai konferencia – 2024
No full textBrüsszel – Magyarország Háza : Márai szalon – könyvtárszoba kialakítása könyvtárszakmai támogatással
No full textExperimental and Numerical Investigation of the Seismic Performance of RC Moment Resisting Frames
Get PDFThe rehabilitation of concrete structures has been a subject of extensive investigation, exploring various facets. One such avenue involves the incorporation of fiber additives into concrete materials. In parallel, the construction of reinforced concrete structures inevitably encounters construction errors, necessitating constant efforts from researchers to devise solutions for mitigating their impact. In the context of this research, a series of experiments was conducted involving the construction and testing of five reinforced concrete moment-resisting frames. The initial sample served as the control, while two additional samples were integrated with polypropylene and metal fibers. The subsequent two samples deliberately introduced a manufacturing error through the application of air-entraining admixture materials at the beam-to-column connection. This deliberate error aimed to assess the influence of additive fibers on frames affected by manufacturing errors. Several critical parameters were subjected to evaluation, including ultimate strength, stiffness, ductility, energy dissipation capacity, and strength reduction factor. The results of these assessments demonstrated that the utilization of additive fibers contributes to an enhanced overall performance of the frames, as inferred from the aforementioned seismic parameters. Furthermore, it was established that the incorporation of these additive fibers substantially alleviates the impact of manufacturing errors on moment-resisting reinforced concrete frames. Although a significant reduction in energy dissipation capacity was observed in samples with manufacturing errors, the other seismic parameters remained relatively unaffected. Subsequently, numerical models were generated in ABAQUS software to validate the experimental findings, and their outcomes were compared with the results derived from the physical experiments
The Effects of Different Solvents on Phenolic, Flavonoid, Anthocyanin Contents and Free Radical Scavenging Activity on Pomegranate Juice and Seeds
Get PDFOur phytochemical investigation defined the polyphenol, anthocyanin and flavonoid content from methanolic, ethanolic 50% and watery extracts from fresh pomegranate juice and seeds with a spectrophotometric method. The antioxidant capacity was defined with the ABTS and DPPH methods. We determined the polyphenols with the Folin-Ciocalteu method, the anthocyanins with the method in Hungarian Pharmacopoeia VIIIth edition at Myrtilli fructus monography and the flavonoids with a modified method of the Romanian Pharmacopeia Xth edition Cynarae folium monography. We expressed the concentration of polyphenols in gallic acids (GA). The values indicated the following: in fruit juice, 47.57 μg GA/ml, in methanol seed extract 7 μg GA/g, the ethanol 50% and in watery seed extracts 8 μg GA/g. The definition of flavonoids indicated the following values expressed in quercetin (QE): in fruit juice 706 μg QE/ml, in methanol seed extract 416 μg QE/g, in ethanol 50% seed extract 46 μg QE/g and in watery seed extract 57 μg QE/g. The anthocyans from juice 3.95 mg/100 ml and seed 6.47 mg/100 g expressed in cyanidin-3-0-glycoside. We determined the following values with the ABTS method: the antioxidant capacity of juice is 25.40 μg/ml, in methanol seed extract 2.87 μg/ml, in ethanol seed extract 2.52 μg/ml, in watery 9.15 μg/ml. With the DPPH method, we obtained the following values: from juice 54.2 μg/ml, from methanolic extract 14.7 μg/ml, from ethanolic extract 10.58 μg/ml and watery extract 18.22 μg/ml. The received data shows the importance of pomegranate, which can be a new phytotherapeutic potential resource
Robust Trajectory Tracking Control of a Differentially Flat Overhead Crane Using Sliding Mode
Get PDFThe control of overhead cranes is a benchmark problem, since it is an underactuated mechanism and its mathematical model is nonlinear. During operation the mass of the load is unknown, representing an uncertainty in the inertial parameters, which requires robustness of the controlled system. Our paper proposes a novel robust control method, that combines the differentially flat property of the dynamics with the robustness of the sliding mode control. The sliding surface is constructed to ensure the tracking of the configuration variables whose accelerations is calculated using the flatness property of the dynamic model. This formulation also allows achieving the matching conditions of the parameter uncertainties. Considering a simplified overhead crane model where the load motion is restricted in a vertical plane, two sliding surfaces are defined for the rope angle and rope length, since the cart position can be calculated from the previous two. The suggested control method is successfully validated in simulations as well as using a reduced-size overhead crane. For the real crane, the rope angle was estimated by utilizing the dynamical model, which uses the estimated cart acceleration
Carbon Capture and Utilization Technology Development Opportunities Based on Biomethanation
Get PDFThe paper provides an overview of Power-to-Gas (P2G) technology using biomethanation and a proprietary biocatalyst. It addresses the issue of carbon dioxide (CO2) emissions from fossil fuel combustion and proposes the integration of Carbon Capture Utilization and Storage (CCUS) technologies with P2G processes. Currently, the integration of CCUS and P2G is in conceptual stage. The paper emphasizes the sensitivity of biocatalysts to contamination in feed gases, particularly the negative impact of oxygen on methanation processes. Findings from measurements conducted in 2022 using a lab-scale prototype approve that post-combustion technologies can be successfully integrated into P2G technologies through the utilization of biomethanation processes. Various parameters, such as Carbon Dioxide Conversion (CDC), Volumetric Methane Production (VVD), and Higher Heating Value (HHV), were calculated based on the measured datasets. The high CDC value of 96.65%(V/V) and 68.03%(V/V) of methane content indicates successful integration of the two technologies, while increasing the CO2 source and applying higher pressure in the biomethanation reactor can further enhance VVD. In conclusion, the paper highlights the potential of P2G technology based on biomethanation and its integration with CCUS processes. The results obtained from the lab-scale prototype demonstrate promising conversion rates and suggest avenues for improving VVD
Strategies for Effective Degradation of Methyl Orange Dye in Aqueous Solution via Electrochemical Treatment with Copper/Graphite Electrodes
Get PDFThis study investigated the electrochemical degradation of methyl orange dye (MO) in aqueous solution using copper/graphite electrodes as anode and cathode respectively. The process parameters such as electrolyte concentrations, current density, pH and temperature were analyzed. The results proved that copper/graphite electrodes were effective for MO degradation and the reaction followed the first-order kinetic model. The degradation efficiency decreased with increasing MO concentration and increased steadily with current density. The pH trend with degradation efficiency was pH 9 (98%) > pH 7 (96%) > pH 3 (77%) after 70 min of electrolysis time, which shows that the alkaline conditions favoured the degradation process. Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy confirmed the dye degradation process, with the formation of degradation intermediates. The FTIR results revealed that the oxidative degradation of MO may be initiated at the N=N azo bond, which was confirmed by quantum chemical modelling of the electronic structure parameters of MO
A Comprehensive Analysis of Chitin Extraction from the Black Soldier Fly for Chitosan Production
Get PDFChitin, a versatile biopolymer with applications in biomedicine, antimicrobial agents, and cosmetics, can be sustainably sourced from the black soldier fly (BSF). This alternative is gaining popularity because it not only provides a sustainable supply of raw materials but also possesses chitin properties. Consequently, this broadens the potential applications of chitin in the development of derivative products with varied characteristics. The BSF undergoes complete metamorphosis, consisting of four stages: egg, larva, pupa, and fly. While the extraction method is commonly used to isolate chitin from other sources, a modified approach is necessary for the BSF due to the unique chitin-binding elements present in its biological structures. Given the high fat content in BSF and its metamorphosis stages, separating the fat prior to the extraction process is crucial. Co-fermentation, a biologically driven extraction technique, offers a cost-effective, environmentally friendly alternative with potential for high chitin yields. These findings underscore the potential of BSF as a sustainable chitin source and emphasize the significance of optimizing extraction processes to produce high-quality chitin and chitosan products. There remains considerable scope for future research, particularly in areas such as the identification of effective bleaching agents, optimizing conditions for maximum chitin extraction from BSF, and refining the extraction process to enhance cost-effectiveness
Multi-objective Investigation and Optimization of Paddy Processing in a Hot Air Dryer
Get PDFIn order to investigate the convective drying of paddy kernels, process time, required energy and head rice yield (HRY) were experimentally measured for different combination of air temperature (40, 55 and 70 °C), velocity (0.6, 1 and 1.4 m/s), drying bed height (18, 25 and 32 cm), and final moisture content of paddy (8, 10 and 12% wet basis). According to the results, at higher temperatures, and for the end-products with higher moisture contents, lower energy was required for drying process, but by increasing the air velocity and sample's bed height the amount of consumed energy increased. The conducted experiments also showed that by changing the drying parameters, HRY varied from 36.32 to 80.56 %. The response surface methodology (RSM) and desirability factor were also used to find optimized conditions and showed that for samples with bed height 18 cm, the convective drying with 59 °C, 0.6 m/s, until the final moisture content of 0.09% wet basis, provides a maximum desirability of 0.791