Search Results (373)

Spot-welding joints are widely used in modern industries, and their fatigue life is crucial for the safety and reliability of structures. This paper proposes a method for predicting the fatigue life of spot-welding joints by integrating traditional structural stress methods and machine learning algorithms. Systematic fatigue tests were conducted on Q&P980 steel spot-welding joints to investigate the influence of the galvanized layer on fatigue life. It was found that the galvanized layer significantly reduces the fatigue life of spot-welding joints. Further predictions of fatigue life using machine learning algorithms, including Random Forest, Artificial Neural Networks, and Gaussian Process Regression, demonstrated superior prediction accuracy and generalization ability compared to traditional structural stress methods. The Random Forest algorithm achieved an R² value of 0.93, with lower error than traditional methods. This study provides an effective tool for the fatigue life assessment of spot-welding joints and highlights the potential application of machine learning in this field. Full article

The future of the automotive industry appears to hinge on the integration of dissimilar materials, such as aluminum alloys and carbon steel. However, this combination can lead to galvanic corrosion, compromising the structural integrity. In this study, laser-welded joints of 6013-T4 aluminum alloy and DP980 steel were evaluated for their morphology, microhardness, and corrosion resistance. Corrosion resistance was assessed using the electrochemical noise technique over time in 0.1 M Na₂SO₄ and 3.5% NaCl solutions. The wavelet function was applied to remove the DC trend, and energy diagrams were generated to identify the type of corrosive process occurring on the electrodes. Corrosion on the electrodes was also monitored using photomicrographic images. Analysis revealed an aluminum–steel mixture in the melting zone, along with the presence of AlFe, AlFe₃, and AlI₃Fe₄ intermetallic compounds. The highest Vickers microhardness was observed in the heat-affected zone, adjacent to the melt zone, where a martensitic microstructure was identified. The 6013-T4 aluminum alloy demonstrated the highest corrosion resistance in both media. Conversely, the electrochemical noise resistance was similar for the DP980 steel and the weld bead, indicating that the laser welding process does not significantly impact this property. The energy diagrams showed that localized pitting corrosion was the predominant form of corrosion. However, generalized and mixed corrosion were also observed, which corroborated the macroscopic analysis of the electrodes. Full article

In this study, we investigated the electrochemical corrosion behavior and mechanisms of FeCrNi/WC alloys with varying contents of CTC-S (spherical WC) and CTC-A (angular WC) in a 3.5 wt.% NaCl solution, addressing the corrosion resistance requirements for stainless steel composites in marine environments. The electrochemical test results demonstrate that the corrosion resistance of the alloy initially increases with the CTC-A content, followed by a decrease, which is associated with the formation, stability, and rupture of the passivated film. Nyquist and Bode diagrams for electrochemical impedance spectroscopy confirm that the charge transfer resistance of the passivated film is the primary determinant of the composite’s corrosion performance. A modest increase in CTC-A contributes to the formation of a more heterogeneous second phase, providing a physical barrier and enhancing solid solution strengthening, and thus delaying the cracking and corrosion processes of the passivation film. However, excessive CTC-A content leads to significant dissolution of the alloy’s reinforcement phase and promotes decarburization, resulting in the formation of corrosion pits, craters, and cracks that compromise the passivation film and expose fresh alloy surfaces to further corrosion. When the CTC-A content is 10% and the CTC-S content is 30%, this combination results in minimal degradation in the corrosion performance (0.213 μA·cm²) while balancing the hardness and toughness of the alloy. Additionally, electrochemical evaluations reveal that incorporating angular CTC-A particles at 10 vol% effectively delays the breakdown of the passivation film by mitigating the interfacial galvanic coupling through enhancing the mechanical interlocking at the WC/FeCrNi interface. The CTC-A/CTC-S hybrid system exhibits a remarkable 62% reduction in the pitting propagation rate compared to composites reinforced solely with spherical WC, which is attributed to the preferential dissolution of angular WC protrusions that sacrificially suppress crack initiation at the phase boundaries. Full article

This study synthesized two eco-friendly inhibitors—a chitosan–copper metal–organic framework (CS@Cu MOF) and chitosan–Schiff base–Cu complex (Schiff–CS@Cu)—for Q345 steel protection in 3.5% NaCl/1M HCl. Electrochemical and weight loss analyses demonstrated exceptional corrosion inhibition: untreated specimens showed a 25.889 g/(m²·h) corrosion rate, while 100 mg/L of CS@Cu MOF and Schiff–CS@Cu reduced rates to 2.50 g/(m²·h) (90.34% efficiency) and 1.67 g/(m²·h) (93.56%), respectively. Schiff–CS@Cu’s superiority stemmed from its pyridine–Cu²⁺ chelation forming a dense coordination barrier that impeded Cl⁻/H⁺ penetration, whereas CS@Cu MOF relied on physical adsorption and micro-galvanic interactions. Surface characterization revealed that Schiff–CS@Cu suppressed pitting nucleation through chemical coordination, contrasting with CS@Cu MOF’s porous film delaying uniform corrosion. Both inhibitors achieved optimal performance at 100 mg/L concentration. This work establishes a molecular design strategy for green inhibitors, combining metal–organic coordination chemistry with biopolymer modification, offering practical solutions for marine infrastructure and acid-processing equipment protection. Full article

This study explores the potential of metakaolin-based geopolymers, activated using sodium hydroxide and sodium silicate, for the solidification and stabilization of heavy metals present in galvanic sludge—a hazardous industrial waste rich in chromium (Cr), nickel (Ni), and iron (Fe). The research investigates factors affecting the cold consolidation of the pastes, such as NaOH molarity (8 or 10 M) and time of preparation of activating solutions (24 h in advance or soon before the fresh paste preparation), the sequence of experimental steps (the sludge added to the fresh paste or to the powder of metakaolin) and amount of waste (10 or 20 per cent by weight over metakaolin). The final products were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and environmental scanning electron microscopy (ESEM). Mechanical performance and durability assessments, including compressive strength and water stability tests, were conducted to evaluate the suitability of the geopolymer for construction applications. Leaching tests according to EU regulation demonstrated promising heavy metal immobilization, highlighting the effectiveness of the geopolymerization process in reducing metal leachability. It was found that the factors affecting immobilization are more evident for Cr than for Ni, whose immobilization percentages are very high. In particular, it was observed that preparing the mixture by adding sludge after metakaolin activation increased Cr immobilization from 83% to 89%. Similarly, preparing the activating solution 24 h before mixing the sludge and geopolymer increased the percentage from 89 to 95. Full article

Persons with personality type D are characterized by an “unhealthy lifestyle”, which is manifested by low physical activity, less healthy eating behavior, and failure to comply with doctors’ recommendations. Persons with personality type D have an inadequate response of hemodynamic parameters to psychoemotional stress; the response of other parameters has not been sufficiently studied. The aim of this study was to investigate the association of personality type D with various psychophysiological parameters of the body during mental stress in healthy individuals. Material and Methods: The study involved 79 students of Kemerovo State Medical University aged 18 to 32 years (mean age 20.7 ± 2.4 years). Psychophysiological diagnostics was carried out using the BOSLAB complex; electromyogram, electrocardiogram, body temperature, respiration, galvanic skin response, and photoplethysmogram data were recorded. The stress testing protocol included cognitive tasks and recovery phases. Additionally, the presence of personality type D in students was assessed using the DS-14 questionnaire. The results of stress tests were compared in groups with the presence/absence of type D. Results: The frequency of detection of type D was high (54.4%). When examining the response of psychophysiological parameters, the most pronounced response to stress tests with mental load was noted for heart rate variability and respiratory system parameters. Individuals with type D personality showed more pronounced sympathetic activation in response to mental stress and a slower recovery at rest. Among the studied parameters, association with personality type D was noted for the following indicators during the mental arithmetic test: heart rate (p = 0.022), the Baevsky strain index (p = 0.004), respiratory rate (p = 0.020), and an indicator of regulatory process adequacy (p < 0.001). Conclusion: In the present study, we found differences in the reaction of psychophysiological parameters to mental stress in healthy individuals depending on the presence or absence of personality type D. These data can be useful for developing stress resistance programs and biofeedback training. The possibility of using the above psychophysiological parameters in biofeedback training programs for individuals with personality type D requires further research. Full article

This study investigates the effects of destructive climatic factors on the mechanical and performance properties of various structural materials, encompassing both polymers and metals. Over recent decades, the growing adoption of synthetic polymers has revolutionized engineering applications, yet their susceptibility to environmental degradation poses significant challenges. This research emphasizes the need for comprehensive testing under both operational and environmental stressors, including extreme temperatures, UV radiation, and moisture, to assess material durability and performance. Mechanical tests were conducted at ambient (25 °C) and low temperatures (−50 °C) to evaluate the strength and strain responses of selected materials. Additionally, a 12-month accelerated aging process using UV radiation and elevated temperatures was performed to simulate long-term environmental exposure. Parameters such as Shore D hardness, gloss, and mass were measured at regular intervals to quantify material degradation. The results revealed significant differences in performance across material types. Among polymers, laser-extruded and milky plexiglass, as well as solid polycarbonate, exhibited satisfactory resistance to aging, with minimal changes in mechanical properties. However, high-impact polystyrene displayed substantial deformation and hardness loss after prolonged UV exposure. For metals, aluminum and stainless steel (304 and 316) demonstrated exceptional durability, retaining structural and aesthetic properties after 12 months of accelerated aging, whereas galvanized steel exhibited pronounced corrosion. The study highlights the critical interplay between mechanical loading and environmental factors, stressing the importance of material selection tailored to specific climatic conditions. It further underscores the value of integrating experimental findings with predictive models, such as finite element analysis, to enhance the design and longevity of engineering materials. The findings provide actionable insights for industries operating in temperate climates, where materials are subjected to diverse and cyclic environmental stressors. Recommendations are offered for selecting resilient materials suitable for protective housings and structural components. Full article

Flat panel displays for large applications (monitors and TVs) have structural weaknesses in improving the yield of mass-produced products due to large panels: the yield is defined by ratio of output quantity to input into panel fabrication process. From a panel manufacturing point of view, low-cost production should be achieved through improved yield of mass production (Samsung Display’s quantum dot display backplane panel). So, we set the target yield at an extreme value, over the golden yield (90%) at the beginning of new mass products. The main factors contributing to the yield loss were “lifted insulator and etched active pattern defects”. To reach the target yield, we focused on these two main defects. The root causes of these defects (delta coefficient of thermal expansion and galvanic corrosion) are explained, and a defect generation mechanism is proposed (the size of the separated large power line in relation to the defect rate). The power lines are defined based on an Electroluminescent Voltage at the Drain (ELVDD) and Electroluminescent Voltage at the Source (ELVSS). We developed a separated large power line design to reduce defect rates. This design plays a role in preventing these two defects during the mass production of medium to large display panels for use in TVs by ensuring that the large power line area is less than the optimum value (<0.44 cm²). Full article

Unmanned systems provide significant prospects for improving the efficiency of electromagnetic geophysical exploration in mineral prospecting and geological mapping, as they can significantly increase the productivity of field surveys by accelerating the movement of the measuring system along the site, as well as minimizing problems in cases where the pedestrian walkability of the site is a challenge. Lightweight and cheap UAV systems with a take-off weight in the low tens of kilograms are unable to carry a powerful current source; therefore, semi-airborne systems with a ground transmitter (an ungrounded loop or grounded at the ends of the line) and a measuring system towed on a UAV are becoming more and more widespread. This paper presents the results for a new generation of semi-airborne technology SibGIS UAV-TEMs belonging to the “line-loop” type and capable of realizing the transient/time-domain (TEM) electromagnetics method used for studying a uranium object of the paleovalley type. Objects of this type are characterized by a low resistivity of the ore zone located in relatively high-resistivity host rocks and, from the position of the geoelectric structure, can be considered a good benchmark for assessing the capabilities of different electrical exploration technologies in general. The aeromobile part of the geophysical system created is implemented on the basis of a hexacopter carrying a measuring system with an inductive sensor, an analog of a 50 × 50 m loop, an 18-bit ADC with satellite synchronization, and a transmitter. The ground part consists of a galvanically grounded supply line and a current source with a transmitter creating multipolar pulses of quasi-DC current in the line. The survey is carried out with a terrain drape based on a satellite digital terrain model. The article presents the results obtained from the electromagnetic soundings in comparison with the reference (drilled) profile, convincingly proving the high efficiency of UAV-TEM. This approach to pre-processing UAV–electrospecting data is described with the aim of improving data quality by taking into account the movement and swaying of the measuring system’s sensor. On the basis of the real data obtained, the sensitivity of the created semi-airborne system was modeled by solving a direct problem in the class of 3D models, which allowed us to evaluate the effectiveness of the method in relation to other geological cases. Full article

In 2022, a working party (fib TG 8.9.3) was formed to try and better develop critical chloride (C_crit) distributions for use in modelling new structures and assessing existing structures. The authors of this paper are leading TG 8.9.3. and are in the process of writing a Bulletin (the Bulletin) that will detail how C_crit values have been developed since the 1970s. The Bulletin notes that chloride-induced corrosion initiation modelling based on C_crit is not intended as a sole durability assessment tool for structures exposed to chloride. It is recognized that voids and moisture at the bar can control corrosion activation virtually independent of chloride content, but in most cases sufficient voids and moisture are present so that the arrival of adequate chloride triggers corrosion activation of the reinforcement. So, durability verification by modelling restriction of chloride penetration, so that the concentration at the bar is less than that commonly found to cause corrosion, seems appropriate. This empirical approach was first fully detailed in fib Bulletin 34 A key part in the empirical model is the ‘adequate chloride to trigger corrosion activation’ C_crit. Although C_crit has a wide distribution and has different distributions in different environments and concrete compositions, its use in modelling provides greater design flexibility and improved confidence compared to the Deemed-to-Satisfy (DtS) rules included in most codes. Because of the limitations in DtS provisions, modelling provides more effective designs by incorporating specific criteria for a broad range of exposures, materials, and construction methods. This paper proposes that a lower bound for C_crit distributions for a range of materials and exposures can be developed from published papers. This paper includes C_crit distributions for steel fibres, carbon steel (above and below water), high tensile steel, galvanized steel, and stainless steels. These are expected to be recommended in the Bulletin. Full article

As the US population ages, the number of prescriptions managed by patients and healthcare teams is increasing. Thus, discontinuing or reducing medications that are considered to pose more risks than benefits can be achieved through deprescribing. Despite increasing calls for a stronger focus on deprescribing in healthcare education, current discussions highlight the lack of training on this topic within healthcare curricula. This is a significant barrier to effectively implementing the deprescribing process. This study aimed to characterize healthcare professional students (HPSs)’s perspectives on deprescribing within an interprofessional healthcare team, particularly regarding the motivations and roles of these future practitioners. Methods: Focus groups were conducted with HPSs at the University of Tennessee Health Science Center. The data collection, guided by a conceptual model, took place over three months in 2022. Data analysis was performed using thematic analysis, during which themes were identified through inductive coding. Results: Participants (n = 36) represented various faculties, including medicine, pharmacy, health professions, nursing, and dentistry. Two themes emerged: (1) Healthcare Team Members’ Roles and Responsibilities (2) “Put Me in, Coach”: Patient Safety Motivates Deprescribing. Conclusion: Data from HPSs highlighted the importance of an interprofessional healthcare team approach to deprescribing. Based on these insights, educators and practitioners should focus on establishing strong interprofessional healthcare teams that privilege open communication. Teams should consider deprescribing as a patient safety concern, as this may galvanize the team and provide additional motivation for performing the necessary work of deprescribing. Full article

This study addresses the multi-period, multi-item, single-stage capacitated lot sizing problem (CLSP) in a parallel machine environment with machine eligibility constraints under a make-to-order production policy. A mixed-integer linear programming (MILP) model is developed to minimize total operational costs, including production, overtime, extra shifts, inventory holding, and backorders. The make-to-order setting introduces additional complexity by requiring individualized customer orders, each with specific due dates and product combinations, to be scheduled under constrained capacity and setup requirements. The model’s performance is evaluated in the context of a real-world production planning problem faced by a manufacturer of cold-formed steel profiles. In this setting, parallel forming machines process galvanized sheets of cold-rolled steel into a variety of profiles. The MILP model is solved using open-source optimization tools, specifically the HiGHS solver. The results show that optimal solutions can be obtained within reasonable computational times. For more computationally demanding instances, a runtime limit of 300 s is shown to improve solution quality while maintaining efficiency. These findings confirm the viability and cost-effectiveness of free software for solving complex industrial scheduling problems. Moreover, experimental comparisons reveal that solution times and performance can be further improved by using commercial solvers such as CPLEX, highlighting the potential trade-off between cost and computational performance. Full article

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries. Full article

This work focuses on the production of ceramic nanofibers from waste materials, which represents a significant contribution to the sustainable use of resources and innovative solutions in the field of nanotechnology. The research builds on existing knowledge of nanofiber production, with a specific focus on the use of zinc galvanizing flue dust. The main objective of the study is to explore the possibilities of converting zinc-containing waste materials into ceramic nanofibers, introducing a new direction in nanotechnology. Laboratory experiments involved leaching processes and electrostatic spinning processes of zinc solutions. From the obtained results, it can be concluded that ZnO ceramic nanofibers produced from both synthetic and real solutions exhibit similar fiber structures. Therefore, it can be stated that both acids (HCl and H₂SO₄) are suitable for preparation. Among them, 0.5 M HCl is the most ideal, resulting in oval fibers with a rough and coarse surface, while 0.5 M H₂SO₄ produces fibers with a different morphology in the form of hollow ribbons, which are presumed to have a higher specific surface area. Thus, it can be concluded that the production of ceramic nanofibers from zinc galvanizing flue dust is feasible and effective, with electrostatic spinning proving to be a low-waste technology. The study also examines the influence of contaminants from real waste solutions on the production of ceramic nanofibers and compares their properties with nanofibers obtained from synthetic solutions. Experimental results suggest that contaminants in real solutions did not have a negative impact on the morphology of the prepared ZnO nanofibers. In conclusion, the production of ZnO ceramic nanofibers from waste offers a promising approach for the future development of nanotechnology, combining innovation with sustainability and efficient resource utilization. Full article

This study was based on the hypothesis that the hybrid type and its physical–mechanical properties significantly influence the operational efficiency of transplanting systems. Understanding these properties is essential for optimizing the performance of semi-automatic and automatic transplanters. To test this hypothesis, a completely randomized design was implemented to evaluate the physical–mechanical properties of tomato seedlings. A total of 1350 seedlings from three F1 hybrids—Natalie (H1), CID (H2), and Gavilán (H3)—cultivated in central Mexico, were analyzed. The statistical analyses included mean comparisons using Tukey’s test and multiple linear regression to estimate the center of mass (CM). The results indicate that H2 was notable for its total height (${\mathrm{h}}_{\mathrm{t}}$ = 311.76 mm), canopy development in X, Y, and Z axes (170.24 mm, 106.84 mm, and 98.14 mm, respectively), stem diameter (${\mathrm{d}}_{\mathrm{s}}$ = 3.65 mm), total weight (${\mathrm{w}}_{\mathrm{t}}$ = 11.92 g), ${\mathrm{d}}_{\mathrm{e}}$ (78.36 mm) and ${\mathrm{d}}_{\mathrm{p}}$ (233.40 mm) distances, and oscillation period (T = 0.88 s). H1 had the highest stem height (${\mathrm{h}}_{\mathrm{s}}$ = 53.18 mm), ${\mathrm{w}}_{\mathrm{t}}$ = 11.76 g, and root ball (RB) moisture content (MC) (77.36%). H3 had the largest ${\mathrm{d}}_{\mathrm{s}}$ = 3.70 mm, as well as the highest MC in the stem (94.51%) and the remaining foliage (92.92%). Regarding mechanical properties, the average adhesion force (AF) was 4.606 N (H1), 7.470 N (H2), and 3.815 N (H3). The average root ball punching force (RBPF) was 0.36, 0.48, and 0.25 N, respectively. The lowest static friction coefficient (SFC) on a galvanized steel sheet was 0.936. The drop test (DT) revealed an average residual substrate mass of 0.148 g at a height of 500 mm. It can be concluded that the interaction between hybrid type, transplanting age, and MC plays a critical role in the efficient design of semi-automatic and automatic transplanting equipment. This interaction enables process optimization, ensures operational quality, reduces seedling damage, and ultimately enhances and increases the long-term profitability and sustainability of the equipment. Full article