Abstract in English:

ABSTRACT This research investigates to remove and strengthen the weak smeared mortar and enhance its quality through sustainable and eco-friendly treatment techniques. The impregnation of recycled coarse aggregate (RCA) in acids (ATRCA) in different molarities was proposed to eradicate the weak smeared cement particle on the RCA and impregnation of RCA in slurries (STRCA) at various dosages was proposed to strengthen the weak smeared mortar on the RCA. The properties of the RCA were assessed prior and after treatment techniques. The micro-structure of the treated RCA was examined through SEM to assess the impact of treatment techniques on the RCA properties. Results infer that both treatments tend to improve the quality of RCA, however slurry treatment strengthens the weak mortar rather than its removal through acid treatment and thus resulting in better properties to RCA. The optimized molarity was observed at 0.3 M for 3 days for acid treatment and optimized slurry dosage was observed at 0.8w/c ratio for 24 hours. The optimized ATRCA and STRCA show 21.70% and 39.07% lesser water absorption than RCA. Similarly, other physical and mechanical properties of ATRCA and STRCA were enhanced compared to RCA. Correlation was established between physical and mechanical properties of the RCA, ATRCA and STRCA. Life cycle assessment of the aggregates was performed with OpenLCA software.

Abstract in English:

ABSTRACT This study investigates the use of waste plastic (polyethylene and polypropylene) and foundry sand to manufacture eco-friendly paver blocks, providing a sustainable alternative to conventional materials. The project aims to address the challenges of plastic waste disposal and environmental damage caused by sand mining. Twelve paver block samples were prepared with varying proportions of plastic (30%–60%) and foundry sand, with or without coarse aggregate. The mechanical properties, including compressive strength, flexural strength, water absorption, and fire resistance, were tested following ASTM standards. The optimal mix, FPA-2 (40% plastic, 40% foundry sand, 20% coarse aggregate), exhibited a compressive strength of 27 N/mm2 and a flexural strength of 6.7 N/mm2, comparable to traditional paver blocks. Water absorption rates were below 7%, and the blocks met fire resistance criteria. Cost analysis revealed that plastic-based paver blocks are up to 25% cheaper than conventional ones, enhancing their economic feasibility. By repurposing waste materials, this study offers a sustainable solution for reducing natural resource dependency and mitigating environmental harm. The findings highlight the potential for plastic-based paver blocks to promote circular economy practices, maintain performance standards, and provide cost-effective alternatives for the construction industry.

Abstract in English:

ABSTRACT This study explores the impact of nano-TiO2 additives on sealing materials for methane drainage boreholes in coal mines. Varying nano-TiO2 contents (0.5%, 1.0%, 1.5%, and 2.0%) were investigated, with 1.5% emerging as the optimal dosage. At this concentration, early-age strength increased by 28.6% at 3 days, while gas permeability decreased by 77.6% compared to the control mixture. The modified sealant exhibited accelerated setting, with initial setting time reduced from 195 to 152 minutes. Fluidity decreased with increasing nano-TiO2 content, necessitating superplasticizer adjustment. Microstructural analysis revealed a 34.2% reduction in total porosity and a refined pore structure. The enhanced performance is attributed to the nanoparticles’ nucleation effect, pore-filling capacity, and participation in pozzolanic reactions. These findings suggest that nano-TiO2-modified sealing materials can significantly improve methane drainage efficiency and mine safety by enhancing borehole airtightness. The study provides valuable insights for developing advanced sealing materials tailored for coal mine applications.

Abstract in English:

ABSTRACT The Zirconium Di- Boride (ZrB2) reinforced AZ64 magnesium metal matrix composite’s (MMMCs) tribological performance was studied for potential use in engineering applications. The composite was developed using the stir-casting method with the help of ultrasonic vibrations for mixing molten AZ64 and preheated ZrB2 particles as it achieves uniform dispersion and better wettability. The physical characteristics was studied through density measurement and the result showed that 3% ZrB2 reinforced composites had an increase in 1.275% of density when related to 0% reinforced MMMCs. The absorbed energy values from charpys impact test of reinforced composites showed an increase of around 85% from the as-cast alloy. The micro hardness of the ZrB2 particles reinforced composite was significantly improved after ultrasonic dispersion. From XRD and EDX it is evident that inclusion of the ZrB2 increased beta-phase precipitation in the Mg alloy, which in turn enhances the strength of the composites. Sliding wear tests were conducted in dry conditions utilizing pin-on-disc (POD) tribometer at standard loads (20–60N) and speeds (1.2–2.4 m/s). Improved wear resistance was seen in the 3% ZrB2 reinforced composites as a result of its finer grain and relatively uniform distribution of ZrB2 particles. Increasing the load resulted in a higher wear rate of the composite at all sliding speeds. Increased capacity of the reinforcement and other characteristics of the produced composite proved to be superior to the AZ64 as cast alloy in all wear test situations.

Abstract in English:

ABSTRACT This study investigates the spray characteristics of non-edible oils, specifically Rapeseed, Jatropha, Neem, and Coconut oils, in Minimum Quantity Lubrication (MQL) systems using Computational Fluid Dynamics (CFD) simulations. The objective was to analyze the effects of MQL parameters—such as inlet air pressure, flow rate, and nozzle diameter—and fluid properties on droplet velocity and diameter. A Discrete Phase Model (DPM) was employed within the CFD framework to simulate the atomization process. Results indicated that increased inlet pressure significantly reduced droplet diameter, with a maximum reduction of 68.35% observed in Coconut oil. Similarly, an increase in flow rate and nozzle diameter led to higher droplet velocities, with the maximum velocity reaching 238.59% of its initial value in Jatropha oil at 6 bar pressure. Viscosity was identified as the most influential fluid property on droplet size, demonstrating a direct relationship with increased droplet diameter. The findings highlight the importance of optimizing MQL parameters and fluid properties to enhance machining performance and reduce environmental impact.

Abstract in English:

ABSTRACT The advancement of nano engineering technology plays a major role in the cementitious materials especially graphene oxide which got high attention. In this research the addition of graphene oxide, silica fume and flyash with various mix proposition in partial replacement of cement have be investigated for mechanical properties of concrete which is the macro level (workability, strength behavior, flexural behavior, water absorption, porosity, and durability) and micro level structural analysis (SEM analysis). Polycarboxylate ethers are used as super plasticizers to offset this decrease, which substantially improves the concrete’s workability. Silica fume and fly ash are utilized in fixed proposition of 10% of silica fume and 10% of fly ash, by weight, to enhance the strength of concrete. After conducting various tests, it has been determined that the optimal combination involves a 10% replacement of both silica fume and fly ash for ordinary Portland cement, particularly grade 53, resulting in superior outcomes. Addition to its varying percentages from 0, 0.01, 0.02, 0.03, 0.04 and 0.05% of Graphene oxide used to find the optimum percentage of GO by weight of ordinary Portland cement to obtain high strength. The optimum percentage of grapheme oxide to be replaced with cement is 0.04%.

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ABSTRACT This study explores the fastening behavior of punctured double-double (DD) laminates, a superior alternative to traditional quadaxial laminates (QUAD) due to improved structural efficiency and lower maintenance. However, the effect of various cutout shapes and sizes on DD laminates’ fastening performance is still unexplored. This research examines optimal ply orientations, rotation angles, and fastening loads for DD laminates with circular, elliptical, and combined-shape cutouts to assess their impact on stability. A hybrid optimization method using an artificial neural network (ANN) and genetic algorithm (GA) is developed to predict maximum buckling loads, avoiding time-intensive finite element analysis (FEA). The ANN models, with R2 values of 0.994 to 0.999, show excellent performance. The best model for circular cutouts achieved R2 is 0.999 with a mean absolute error of 0.0059. Results indicate that elliptical and combined-shape cutouts significantly influence ply angles and buckling loads. Combined-shape cutouts offer superior stability as size increases, with buckling load improvements of 15% over circular cutouts. This study highlights the potential of ANN-GA techniques for optimizing DD laminate designs and improving structural performance.

Abstract in English:

ABSTRACT Predicting the adhesive force between steel reinforcement and concrete is crucial as it influences stress distribution and the overall mechanical behavior of reinforced concrete. This study proposes a novel approach to enhance bond strength prediction using machine learning (ML) models optimized through Bayesian optimization (BO). A dataset comprising 401 beam tests with six key factors was used to train three distinct ML algorithms—Support Vector Regression (SVR), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). The prediction models were first trained on the full dataset, with BO applied to fine-tune hyperparameters and improve accuracy. Among these models, the BO-XGBoost achieved the best performance, with an R2 of 0.74, MAE of 1.412 MPa, and RMSE of 1.516 MPa on the test set, and R2 = 0.80, MAE = 0.950 MPa, RMSE = 1.200 MPa on the training set. In addition, a simplified model was developed, incorporating only three critical variables—rebar thickness, reinforcement tensile strength, and concrete compressive capacity—to make the model more applicable in real-world engineering scenarios. To further interpret the model’s predictions, Shapley additive explanations (SHAP) were employed, revealing the specific influence of each variable on bond strength. This study demonstrates that the integration of ML with Bayesian optimization can significantly improve the accuracy of bond strength predictions, offering valuable insights for structural design optimization.

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ABSTRACT Sustainable pavement construction is essential for promoting ecological balance and reducing the environmental impact of infrastructure projects. This study investigates the viability of partially replacing conventional fine aggregate (river sand) with steel slag in proportions ranging from 10% to 100% by volume for pavement quality concrete (PQC). The mechanical properties of PQC were evaluated following IRC standards, with a focus on compressive strength, flexural strength, split tensile strength, and fatigue performance. Additionally, the study assessed the concrete’s abrasion resistance and skid resistance, critical for ensuring durability and road safety. The experimental results demonstrated that incorporating steel slag as a fine aggregate replacement significantly enhances the mechanical performance of PQC. A mix containing 40% steel slag exhibited optimal improvements in compressive, flexural, and tensile strengths, alongside superior resistance to wear and skid. These findings indicate that steel slag, when used in appropriate proportions, can enhance both the durability and safety of concrete pavements. The study highlights the potential of steel slag as a sustainable and resource-efficient alternative to conventional materials in pavement construction, contributing to environmental sustainability and improved infrastructure performance.

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ABSTRACT The study explores the perforating shear performance of Fiber-Reinforced Polymer (FRP) concrete blocks using machine learning techniques like Gradient-Boosted Regression Trees (GBRT), k-nearest Neighbours (KNN), and Lasso Regression. It aims to predict the structural integrity of FRP blocks under shear conditions based on experimental data. The models were assessed using Coefficient of Determination (R2), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE). GBRT demonstrated superior performance during training with an R2 of 0.9786, RMSE of 52.75, and MAE of 34.12, indicating strong predictive accuracy and minimal error. It outperformed KNN (R2 = 0.92, RMSE = 83.91, MAE = 45.71) and Lasso Regression (R2 = 0.71, RMSE = 162.45, MAE = 115.83). In validation, GBRT again excelled with an R2 of 0.93, RMSE of 76.23, and MAE of 58.46, confirming its robustness in generalizing unseen data. KNN showed lower performance in validation (R2 = 0.86), with increased error values, while Lasso lagged further behind (R2 = 0.681, RMSE = 185.23, MAE = 138.34). GBRT consistently outperformed traditional regression methods, highlighting its potential for more accurate and reliable structural analysis in FRP concrete slabs.

Abstract in English:

ABSTRACT Double-skinned steel-concrete composite columns are famous nowadays in the construction industry because of their structural advantages. The analysis of the performance of double-skinned composite columns with two steel skins of the outer and inner tube, in addition to an in-built steel core in-filled with concrete, was attempted. Steel skins can serve multiple functions, notably defining the geometry of the concrete column and preventing cracks from tensile pressure. This article consists of the research work, numerical and experimental investigation, of the behaviour of Double-Skinned Square Composite Columns (DSSCC) with square cores in-filled with concrete under axial compressive load. The square steel tubes are of size 150 and 50 mm with 6 and 3 mm thickness of outer and inner tubes, respectively, and a height of 500 mm characterized by an inner core of 1 mm thickness. The steel tube considered in the current numerical study (using Abaqus 6.14) is of grade Fe250, Fe350 and Fe415, and in-filled concrete is of grade M20, M25, M30, M35, M40 and M45. The steel tube considered in the present experimental study is of grade Fe250, in addition to the steel cores, which are made of grade A1008 cold-formed steel. The average compressive strength of the concrete used in an experimental study, after 28 days of curing, is measured as 26.07, 32.89 and 40.29 N/mm2. The current study was performed to find the axial compressive behaviour, ultimate load, load versus vertical and horizontal deflection behaviour and corresponding stress and strain value and failure modes. Stiffness, ductility ratio and energy absorption capacity were determined from the observed test values. The results show that increasing concrete compressive strength improves the load-carrying capacity of the column. The experimental and numerical results were discussed and validated.

Abstract in English:

ABSTRACT Worn-out or used abrasive particles from abrasive water jet machining are found to be wasted without recycling in most cases, as they contain different metal and non-metal particles with respect to their application. The abrasive waste obtained from abrasive water jet machining can be gainfully utilized in various engineering applications. Owing to the same, the present work attempts to recycle and reuse the same for manufacturing kenaf fiber-reinforced hybrid polymer composites. Polymer composites were synthesized using the hand lay-up method, incorporating kenaf natural fibers, epoxy resin, and recycled spent abrasive particles. The spent abrasive particles collected from abrasive water jet machining were chosen as the filler material, and they were mixed in different weight percentages with epoxy resin to fabricate a kenaf fiber-reinforced hybrid polymer composite. The effects of recycled spent abrasive particle filler addition on the tensile, flexural, and impact behaviour of the synthesized polymer hybrid composites were examined. Fractured samples with different filler compositions were examined using a scanning electron microscope to probe the failure patterns. The experimental results revealed positive trends in the enhancement of mechanical properties with the inclusion of the spent abrasive particles.

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ABSTRACT Carbon nanotube (CNT)-based sensors are revolutionizing human motion detection through their unique combination of flexibility, sensitivity, and durability. This review examines the transformative impact of these sensors across healthcare, sports science, and wearable technology. Recent breakthroughs in hierarchical sensor architectures and hybrid materials have achieved unprecedented performance, with sensitivity exceeding conventional sensors by orders of magnitude and response times in milliseconds. These advances have enabled applications ranging from rehabilitation monitoring to high-precision athletic performance analysis. The integration of artificial intelligence with CNT sensors is opening new possibilities in personalized healthcare and human-machine interfaces. While challenges remain in manufacturing scalability and long-term stability, emerging developments in self-powered systems and biocompatible designs point toward widespread adoption in next-generation wearable devices. This review synthesizes current progress and identifies promising directions for future innovation in CNT-based motion sensing technology, highlighting its potential to transform how we monitor and understand human movement.

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ABSTRACT This study investigates the optimization of Wire-Cut Electrical Discharge Machining (WEDM) for 2304 duplex stainless steel, a material valued for its superior mechanical properties and corrosion resistance in challenging environments such as oil and gas, marine, and chemical industries. The study aims to evaluate how WEDM parameters—pulse duration, peak current, and wire speed—affect MRR, surface roughness (Ra), and tool wear. Using a Taguchi-based design of experiments (DoE) method, machining trials were conducted by varying these parameters. Results showed that Material Removal Rate (MRR) and surface roughness increased with longer pulse durations and higher peak currents, demonstrating a direct relationship. MRR peaked at 8.8 mm3/s at 300 µs pulse duration and 30 A peak current, while surface roughness increased to 2.1 µm under the same conditions. ANOVA analysis confirmed that pulse duration had the most significant effect on MRR and surface roughness, accounting for 58% and 54% of the variation, respectively. Tool wear, which increased with higher discharge energies, was mainly influenced by peak current, contributing to 45% of the observed variance. This study concludes that optimizing WEDM parameters can enhance machining performance while balancing MRR, surface finish, and tool wear trade-offs.

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ABSTRACT This study investigates the treatment of Sago Wastewater (SW) using natural materials and α-Al2O3 ceramic membranes for filtration. SW samples were collected from influent and effluent of sago industries in Salem and Namakkal districts, Tamil Nadu, as well as from nearby open wells and bore wells. The physico-chemical parameters, including pH, color, turbidity, TSS, TDS, TS, DO, COD, and BOD, were analyzed. High levels of BOD (1800–1550 mg/L) and COD (3400–4150 mg/L) were observed, reflecting the high organic content of the effluents. Post-filtration, pH values ranged from 6.9 to 7.3, with BOD and COD levels within permissible limits set by TNPCB. Toxic substances were reduced by 52% to 96%. Statistical analysis using multiple linear regression showed an R2 of 0.98 in the predicted phase and 0.9 in the treatment phase, while CNN analysis yielded an R2 of 0.99 with an MSE of 5.9 after 2000 epochs. The filtration process significantly reduces toxins, making the treated water suitable for irrigation purposes.

Abstract in English:

ABSTRACT When used as a surface layer on permeable pavements, pervious concrete promotes water percolation, thus helping urban water runoff management. Water percolation occurs due to its porous structure, and interconnected pores are fundamental for its efficiency. To better understand pervious concrete, this study aimed to analyse the porous structure and mechanical and hydraulic properties of pervious concrete. Compressive strength, flexural tensile strength, porosity and permeability coefficient tests were performed. The porous structure was characterised using three approaches: ImageJ software, Sketchup software and scanning electron microscopy. According to hardened state results and Brazilian technical standards, pervious concrete can be used cast-in-place for pedestrian traffic or light vehicular traffic areas. Pervious concrete pores’ length, perimeter, Feret’s diameter and width increase, while circularity and the number of pores decrease as the void volume increases, indicating that as the volume of voids in pervious concrete increases, the pores become larger, more elongated and smaller in quantity. Good to excellent correlations were found between the concrete’s compressive strength, flexural tensile strength and permeability coefficient and the concrete’s porosity, pore area, pore volume and geometric tortuosity, although different image analysis methodologies were used to obtain the porous structure data.

Abstract in English:

ABSTRACT Research has been conducted regarding the influence of Si3N4 micro-particle reinforcement with alloy on the mechanical and wear properties of AZ61/Si3N4 composites. The stir casting technique has been used to create AZ61/Si3N4 composites. Particles of Si3N4 with sizes between 15 to 40 μm and weight percentages of 4, 8, and 12 were mechanically injected into molten AZ61 alloy in an argon gas atmosphere and stirred at 400 rpm. Hardness and impact were shown to be increased gradually with the addition of 4wt.%–12wt.% Si3N4 reinforcement to the composites. Experiments were carried out using a Pin-on Disc tribometer at ambient temperature to simulate the wear rate. To enhance the predictability of wear rate and streamline the tests, a 3-level CCD utilizing RSM was devised. The created model accurately predicted the wear rate with a 95% level of confidence, and its overall validity was confirmed using analysis of variance.

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ABSTRACT This study presents the development and validation of a new electrochemical method for measuring electrolyte density and assessing stratification in lead-acid batteries. The proposed methodology is based on the potential difference between two electrodes, one composed of PbO2 and the other of Pb, both prepared and characterized through cyclic voltammetry. The formation and morphology of the electrodes were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealing characteristic three-dimensional structures. Tests with electrolyte solutions of known density demonstrated an excellent correlation between the measured potential difference and the actual electrolyte density, with an accuracy of ±0.001 g/cm3 compared to measurements made with a portable digital densitometer. The practical application of the method in lead-acid batteries, conducted on a 60Ah commercial battery, validated the proposed technique, showing significant correlation with data obtained from commercial equipment. The study highlights that electrolyte stratification is a critical issue in lead-acid batteries, and the developed method provides an effective and low-cost tool for monitoring this phenomenon. The technique can be applied in various research efforts to improve the performance and durability of lead-acid batteries.

Abstract in English:

ABSTRACT This study presents the development and validation of a new electrochemical method for measuring electrolyte density and assessing stratification in lead-acid batteries. The proposed methodology is based on the potential difference between two electrodes, one composed of PbO2 and the other of Pb, both prepared and characterized through cyclic voltammetry. The formation and morphology of the electrodes were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealing characteristic three-dimensional structures. Tests with electrolyte solutions of known density demonstrated an excellent correlation between the measured potential difference and the actual electrolyte density, with an accuracy of ±0.001 g/cm3 compared to measurements made with a portable digital densitometer. The practical application of the method in lead-acid batteries, conducted on a 60Ah commercial battery, validated the proposed technique, showing significant correlation with data obtained from commercial equipment. The study highlights that electrolyte stratification is a critical issue in lead-acid batteries, and the developed method provides an effective and low-cost tool for monitoring this phenomenon. The technique can be applied in various research efforts to improve the performance and durability of lead-acid batteries.

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ABSTRACT This study employs machine learning (ML) to analyze the melting and reconsolidation behaviors of iron, emphasizing the influence of cold reduction ratios and rolling sequences. Five samples with varied cold reduction ratios and rolling patterns were examined. Findings indicate that when the cold reduction ratio exceeds 65%, coordinated cold melting minimally impacts crystallographic consistency. Texture formation remains largely unaffected during cold melting and short-duration annealing. However, extended annealing prompts irregular grain growth, altering crystal orientation. Sheets rolled in alignment with their initial condition exhibit consistency patterns similar to conventionally cold-melted pure iron after prolonged annealing. Key parameters influencing material performance were evaluated, revealing annealing temperature as the most significant factor (5.94), followed by cold melting direction order (1.46), while the hanging period during annealing had minimal impact (1.02). ML models were employed to predict Goss angle expansion using cold-rolling and annealing parameters. This approach demonstrates the potential of ML to predict texture evolution in pure iron, offering valuable insights for optimizing industrial cold-rolling practices.

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ABSTRACT This experimental study investigates the axial compression effect of rectangular pultruded glass fiber-reinforced polymer (P-GFRP) tubular column sections, examining the impact of width-to-thickness ratio (B/t), aspect ratio (H/B), and column height on their structural performance. A total of 27 GFRP columns were subjected to axial compression tests to evaluate their ultimate load and initial stiffness. The columns exhibited a uniform failure pattern, characterized by crushing, mid-section fractures, and longitudinal splitting at the corners. The results revealed a negative correlation between the ultimate load and the aspect ratio, as well as the width-to-thickness ratio. This study utilized advanced machine learning algorithms, namely Response Surface Methodology (RSM) and Artificial Neural Network (ANN), to develop predictive models for the ultimate load of GFRP columns. The RSM model achieved an R2 value of 0.8347, demonstrating good accuracy in predicting ultimate load. The ANN model outperformed the RSM model, with an R criterion exceeding 0.68807 across training, testing, and validation phases, showing a stronger correlation between experimental and predicted outcomes. This research establishes a framework for forecasting the mechanical properties of column sections.

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Abstract Increased electricity demand in urban and rural areas necessitates renewable energy solutions such as wind power, which is sustainable and non-polluting. However, low wind velocity regions face challenges in adopting small horizontal axis wind turbines (SHAWTs) due to the limited performance and designs under low Reynolds numbers. This study addresses the need for optimized airfoil solutions to enhance SHAWT efficiency under these conditions. The research focuses on the development and analysis of a novel airfoil material, VIT7510, specifically tailored for low wind speeds. Advanced tools such as QBlade software, incorporating XFOIL solvers and Blade Element Momentum (BEM) theory, were utilized to evaluate the aerodynamic properties of the material in terms of lift-to-drag ratio (CL/CD), power coefficient (Cp), and efficiency. Key findings demonstrate that the VIT7510 achieves a maximum CL/CD ratio of 122.89 at an angle of attack of 4.9° and a power coefficient of 0.550 at a tip speed ratio of 4.9. The material outperformed 25 other airfoils, including those from NACA, Selig-Donovan, and Eppler families, under low wind conditions. These results highlight the potential of the VIT7510 material in SHAWT applications, offering a robust solution for energy generation in low-wind regions.

Abstract in English:

ABSTRACT In recent days the natural fiber reinforced polymer composites getting more attention due to their eco-friendly and reliability in many parts of the industries. The lignocellulosic content in natural fibers influenced to use in corrosion and thermal free applications. The hybrid fiber reinforced composites additionally provides the combination of material properties together, the orientation of fiber reflects in strength of the composites as it acting as load bearing factor of the fiber reinforced composites. So, the present work investigates the effect of hybridization and stacking sequence on various material properties such as density, moisture intake by the material, tensile, impact, hardness and thermal stability. The structural characteristics of the fabricated composites is analyzed through Scanning Electron Microscope. The results concludes that the hybridization of glass fiber mat with cellulose fibers mat such as Pineapple Leaf fiber (PALF) and areca fiber depicts the more acceptable bonding relationship with the matrix thus results in improved properties. The fabricated new set of natural and glass reinforced polymer composites have found the tensile strength between 40–65 MPa, Young’s modulus in the range 950–1400 MPa, Impact strength of about 130–190 KJ/mm2 and thermal stability up to 340–390 °C which is higher than the earlier studies reported.

Abstract in English:

ABSTRACT Cementitious Green Hybrid Concrete (CGHC) is gaining recognition as a sustainable choice for low-volume roads, providing environmental benefits and improved mechanical strength over traditional concrete. CGHC reduces traditional cement demand, thus lowering carbon emissions, while its durability minimizes repair needs, extending structural lifespan and reducing resource consumption. This study employs Response Surface Methodology (RSM) with a Central Composite Design (CCD) to analyze the influence of varying proportions of cement, fine aggregate, and coarse aggregate on CGHC's compressive and flexural strengths. The investigation evaluates the impact of coconut shell (COS), lime powder (LP), and rice husk ash (RHA) as partial replacements—substituting COS for coarse aggregate, RHA for fine aggregate, and LP for cement across twenty M30 grade concrete mixes. Results show that RHA and LP replacements generally enhance strength, with RHA substitution at 20% for fine aggregate yielding optimal strength. In contrast, increased COS content reduces strength. This research demonstrates RSM's effectiveness in optimizing CGHC properties, underscoring its potential for eco-friendly road applications.

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ABSTRACT The Cost of Quality (COQ) is widely recognized in manufacturing as a critical performance metric, yet its application in the construction industry remains less established due to fundamental differences in characteristics and environments. While integrating COQ into the planning and building phases of construction projects appears straightforward in theory, practical implementation proves challenging. This study investigates the impact of COQ elements on total quality costs, analyzing 16 building projects using factorial design techniques. Internal and external failure costs emerged as significant factors affecting overall quality, with variations in prevention, appraisal, and failure costs emphasizing the critical role of preventive measures in minimizing quality-related expenses. Statistical hypothesis testing confirmed the substantial influence of failure costs on total quality costs, with Yate’s algorithm and 24 factorial design experiments offering deeper insights into factor effects. The findings underscore the importance of strategic preventive actions, providing valuable implications for enhancing quality management practices, reducing failure costs, and improving overall project efficiency in the construction sector.

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ABSTRACT In order to improve the removal of methylene blue dye from water, zinc oxide nanoparticles (ZnO NPs) were synthesized utilizing Annona squamosa leaf extract as a green reducing agent. Particle size analysis (PSA), FT-IR, XRD, FE-SEM, and EDX) were among the methods used to characterize the ZnO NPs. Following batch adsorption tests, the effectiveness of these nanoparticles in removing dye was evaluated. Many factors were carefully examined, including pH, temperature, initial dye focus, and adsorbent dosage. The outcomes demonstrated a strong agreement between the second-order kinetics of the process of adsorption and the Langmuir isotherm model. The process is exothermic, according to thermodynamic study, which also estimated important parameters like ΔH°, ΔS°, and ΔG°. The dye removal effectiveness reached up to 99% under ideal conditions, which included a contact period of 60 minutes, an adsorbent dosage of 0.1 g, an initial dye concentration of 80 ppm, and a pH of 8.0. Consequently, the produced ZnO NPs show great promise as an efficient adsorbent for removing methylene blue dye, especially when it comes to treating pharmaceutical wastewater.

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ABSTRACT Titanium alloys are utilized in many fields of science, engineering, and technology because of their superior mechanical and tribological properties. The investigation goal is to develop an innovative composite for use in the automobile industry by applying additive processes such as selective laser melting and reinforcing titanium alloy with bio-silica. Bio-Silica (BS) nanoparticles are extracted using agricultural waste of Calotropis gigantea as reinforcement. The Industrial Grade Titanium (IGT) alloy nanocomposites are employed for making alloys with bio-silica nanoparticles reinforcement of 0, 5, 10, and 15%. The IGT/BS nanocomposites mechanical properties, such as microhardness, tensile (ultimate and yield) strength, and compressive strength, were investigated. According to the investigation's outcomes, 15wt.%IGT/BS nanocomposites had better mechanical characteristics. L9 Taguchi's orthogonal array is utilized to illustrate the wear trials. ANOVA is used to optimize outcomes. The ANOVA was utilized to determine the ideal process parameters that would result in the lowest possible wear rate and coefficient of friction (COF). The findings indicated that the applied load of 30 N, sliding velocity of 4 m/s, and sliding distance of 2000 m may achieve the lowest wear. According to an ANOVA, load is the most significant factor (30%) influencing wear.

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ABSTRACT Composite materials, renowned for their superior mechanical properties and lightweight characteristics, are widely used in high-precision industries such as aerospace, automotive, and chemical manufacturing. The production of composite components heavily relies on high-quality molds, where contaminants like mold release agents and resins accumulate over time, compromising the surface quality and durability of both the mold and the composite products. This study investigates laser cleaning as a non-contact, sustainable method to remove these contaminants while preserving material integrity. Surface characteristics were analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The optimal laser parameters—200 W power, 2500 mm/s scanning speed, 2000 kHz repetition rate, 40 ns pulse duration, and a 0.01 mm scanning interval—effectively removed contaminants and improved surface quality, reducing roughness from 1.840 μm to 0.474 μm. Additionally, mechanical properties were assessed using a micro hardness tester and a multi-function tribometer, showing a 13% increase in surface hardness and an 8% improvement in wear resistance, indicating enhanced surface tribological properties. These findings underscore the potential of laser cleaning to maintain composite mold quality, extend service life, and provide an efficient, environmentally friendly alternative to conventional methods.

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ABSTRACT The growing global energy demand and environmental concerns underscore the importance of optimizing solar water heating systems (SWHS) with an emphasis on material properties to enhance thermal efficiency. Despite technological advancements, challenges in material selection, riser tube design, and operational parameters limit the performance of SWHS. This study focuses on optimizing the thermal efficiency of a solar flat plate collector by integrating material analysis within a combined Computational Fluid Dynamics (CFD) simulation and Response Surface Methodology (RSM) framework. By exploring the effects of riser count, material conductivity, mass flow rate, and inclination angle, the study demonstrates how material properties significantly influence heat transfer. Copper, as the absorber material, exhibited superior thermal performance, with optimized conditions achieving a maximum outlet temperature of 350.61 K. The combined CFD-RSM methodology minimized experimental iterations and provided a deeper understanding of the interplay between material properties and system dynamics. These findings highlight the critical role of material selection in developing cost-effective, high-efficiency solar absorbers. Future research should investigate advanced materials and innovative geometries to enhance the performance and sustainability of SWHS further.

Abstract in English:

ABSTRACT The Design of Experiment (DOE) technique was used to assess the impact of factors such as silica fume, bamboo fibers, and jute fibers on concrete strength. The Box–Behnken design of Response Surface Methodology (RSM) identified the optimal combination of variables and their effects on split tensile and compressive strength at 14 and 28 days. Pareto charts and Analysis of Variance (ANOVA) were used to analyze regression models for these responses. In this study, the jute and bamboo fibers with Silica Fume mixed concrete (each 0.5%) provides the maximum compressive strength of 30.27 MPa and split tensile strength of 3.19 MPa after 28 days of curing. After determining each progression variable’s statistical significance, second-order polynomials were used to create the resulting models. The quality of concrete strength was increased by adding bamboo and jute fibers along with silica fume and further addition of these fibers may reduce the strength of the concrete. The Response Surface and Pareto chart recommended the most significant and influential element for spilt tensile strength is jute and bamboo fibers, and for compressive strength is a jute fiber. Regarding split and compressive strength, the validation test percentage error is less than 3% and 4%, respectively.

Abstract in English:

ABSTRACT Long-neck glass bottles are not returned for reuse by the industry, which has generated a large quantity of waste with environmental impacts for current and future generations. The main raw material employed to synthesize geopolymeric materials is metakaolin, although the relationship between silica and alumina content is not ideal. Often, the silicates in the activating solution complement the required SiO2 content. An eco-efficient option would be to use long-neck bottles as an additional source of silica. This work evaluates plastic viscosity, microstructural, and mechanical characteristics of non-conventional metakaolin geopolymers based on long-neck bottles waste incorporation from the replacement of 0, 10, 20, and 30% of metakaolin with waste from blue, green, and amber long-neck bottles. The best combinations of SiO2/Al2O3, NaOH concentration, and curing temperature were selected to produce geopolymers, which were evaluated through rheology, x-ray diffractometry, and compressive strength. The results indicate a lower flow resistance of geopolymers with residue, in accordance with the increase in the residue content in the system. The occurrence of geopolymerization was observed with and without glass waste, with ambient and thermal curing. The compressive strength, at 90 days of the geopolymers with 10% replacement was higher than the value of the reference sample by 4.1%, 29.1% and 21.0% for the blue, green and amber long neck residues, respectively.

Abstract in English:

ABSTRACT Alloys of the Al-Mg-Sc system are possible options for use in aircraft aiming to reduce structural weight and fuel consumption, due to the demand for advanced metal alloys with better properties, but at a less attractive cost. Considering the potential of these alloys, the present work aimed to evaluate the use of Scalmalloy® in one aircraft component: wings spars, and the values of desired properties for this component were discussed. The mechanical properties of these alloys were consulted in the Aleris datasheet for alloys 5024 and 5028. Consultations were made to the data in the literature, and subsequent comparisons of values of the mechanical properties and Merit Indexes: E1/2/ρ, δy2/3/ρ, E1/2/Cmρ, δy2/3/Cmρ between Scalmalloy® and the traditional alloys, using Cambridge Engineering Selector® 2019 software. It can be seen in the results indicated in Ashby diagrams and tables produced that, for wings spars, the Al-Mg-Sc AA5028-H116, produced by additive manufacturing, has the highest index E1/2/ρ equal to 3.19 and the highest index δy2/3/ρ equal to 25.313. However, the index E1/2/Cmρ is equal to 0.17 and the index δy2/3/Cmρ is equal to 1.35. Therefore, it was found that AA5028-H116 has the potential to replace the traditional alloys, despite its higher price.

Abstract in English:

ABSTRACT Due to the huge demand and scarcity for river sand, there is a desperate need for a Quantitative, Qualitative and Environmentally friendly alternative for river sand. As aggregate is the second largest resource used next to water, the alternative for river sand suggested should be not only of good quality but also should be available in enough quantity to be substituted for river sand. Such alternate choices should not just satisfy the structural requirements but also not affect the environment. In this regard, the environmental valuation of mountains is carried out to assess the benefits and limitations of using M sand as a substitute for river sand. In this study, the chemical properties of M sand samples from various locations are determined along with the lifecycle assessment of M sand. Finally, the Environmental Valuation of mountains is done to determine if the negatives outweigh the benefits. From the results, the various methods to resort to in order to achieve a sustainable level of replacement of M sand with river sand are discussed.

Abstract in English:

ABSTRACT This work examines the impact of altering the water-binder ratios (w/b) and cement/silica fume (SF) replacements on the strength at the compression of High-Performance Concrete (HPC), both before and during prolonged contact with extreme temperature. After preparation and testing, eighteen mixtures were produced. Based on the variation in weight/bulk density, the compressive strength test results at room temperature varied from 58 to 102 MPa. In addition, a novel technique known as “heat endurance” has been implemented to compare HPC responses at high temperatures. The findings demonstrate that pozzolanic interaction with the fillers component of SF improves HPC’s residual compressive strength following exposure to high temperatures. Comparative measurements of retained strength of compression were greatest for blends containing 6%, 12%, and 15% of SF at w/b ratios of 0.30, 0.35, and 0.40. As a consequence, altering the w/b ratio had a substantial impact on the outcomes. Lastly, a variety of measuring methods were offered to assist with the study, such as CT, SEM, and thermogravimetric (TG) analysis to evaluate the microstructure modification, porosity, and mass loss of HPC.

Abstract in English:

ABSTRACT Concrete is the most used construction material, which results in harmful impacts on the environment due to the consumption of natural resources. Hence the need to use alternative materials, e.g., waste from the construction sector and even from other production sectors. This context includes the development of concrete with sustainable functionality, such as pervious concrete with the incorporation of waste foundry sand (WFS), a waste generated by the foundry sector. However, there is a scientific gap focusing on the environmental viability of pervious concretes. In this sense, this study aims to evaluate the toxicity of pevious concretes with WFS, through germination tests with Eruca sativa (arugula) and Triticum aestivum (wheat) seeds. The statistical analysis of the results showed that there was no significant harmful effect from the incorporation of WFS on the germination rate for both seeds used. Regarding root growth, it was observed that WFS II concrete (>% Portland cement) had a lower impact on arugula seeds (more sensitive). Therefore, the pervious concrete with WFS developed was found to be safe in relation to phytotoxicity.

Abstract in English:

ABSTRACT Cyclones are industrial equipment widely used to induce the separation of suspended solid particles based on a driving force related to the terminal velocity in fluid flow. They are applicable to both gaseous and liquid fluids (hydrocyclones), enabling separation between the solid-fluid physical states. The physical principle behind the separation and operation phenomenon is inertia, utilizing centrifugal force to displace air, consequently facilitating the removal of particulate matter present in the stream. One of its main functions is gas cleaning in industrial processes, due to its low acquisition, operation, and maintenance costs, along with the ability to handle streams at high pressures and temperatures. The primary objective of this study is to simulate the flow and disaggregation profiles in a cyclonic separator using computational fluid dynamics (CFD) via finite volumes, where a control volume is subdivided into discrete elements aimed at referencing points within the continuous domain. This approach enables the application of constitutive equations, converting partial differential equations into systems of linear equations. This study applies the method to a Lapple-type cyclone, validating the numerical results obtained with those available in the scientific literature under the same operating conditions. The comparative parameter used to estimate the relative error was the pressure drop. As a secondary objective, the applicability of the cyclone for neutralizing the hazardous chemical agent ammonia was evaluated. This was achieved through its chemical reaction with acetic acid, enabling a realistic hypothetical leakage study to investigate the possibility of formulating emergency plans. In the event of an industrial accident involving ammonia dispersion, this system could be activated. For this purpose, a multiphase plug flow reactor (PFR) was designed, estimating the conversion, reaction time, and dynamic concentration profiles for the synthesis of ammonium acetate, a chemical agent with lower toxicity compared to ammonia.

Abstract in English:

ABSTRACT In order to investigate the effect of periodic solar radiation on oil vapor diffusion and small breathing losses in dome roof tanks, a theoretical model of unsteady heat and mass transfer in dome tanks is established based on the ASHRAE clear-sky model and oil evaporation theory. The heat flux UDF is self-programmed, and CFD software is used to simulate the heat and mass transfer process in the gas space of the dome tank. Dynamic mesh technology is used to realize the overpressure relief of the breathing valve and calculate the small breathing losses. The results show that the gas space temperature decreases from top to bottom; it has a concave and convex distribution near the tank wall. The average temperature decreases with increasing liquid level. The vapor concentration in the gas space increases from top to bottom, and there is a clear concentration layer near the liquid level. The average vapor concentration increases with the liquid level. Gas space pressure increases gradually from top to bottom. The number of breathing valve exhausts decreases with the increase in liquid level. The small breathing losses increase with the liquid level and the seasonal warming, and the loss rate increases with the seasonal warming.

Abstract in English:

ABSTRACT The morphology of LPSO phase, mechanical properties and fracture behavior of Mg-8Gd-5Y-2.5Zn-0.6Zr (wt%) alloy were systematically studied. The microstructure of as-cast and homogenized alloys is mainly composed of α-Mg matrix and Mg12(Gd,Y)Zn eutectic phase (LPSO phase). The as-cast alloy contains a large number of fine block 18R LPSO phases, which can be transformed into lamellar, rod-like and large block 14H LPSO phases after homogenization at 520°C for different time. Homogenization treatment can significantly improve the mechanical properties of Mg-8Gd-5Y-2.5Zn-0.6Zr alloy, especially the plasticity. The fine block and lamellar LPSO phases are prone to stress concentration, causing transgranular cleavage fracture, thereby damaging the mechanical properties of the alloy. The rod-like LPSO phase is easy to form pinning effect in the matrix, which can effectively improve the mechanical properties of the alloy and cause transgranular and dimple fracture, so that the alloy obtains the best ultimate tensile strength, yield strength and elongation, which are 252MPa, 214MPa and 17.2%, respectively.

Abstract in Portuguese:

RESUMO O processo de corrosão nos metais compromete a estrutura e o funcionamento de diversos materiais utilizados no cotidiano. Revestimentos e modificações superficiais que retardem a evolução do processo corrosivo são os métodos de proteção mais utilizados. Os revestimentos termodifundidos de carboneto de vanádio foram desenvolvidos para melhorar o desempenho e a vida útil de ferramentas de aço para conformação plástica de metais. Neste trabalho avaliou-se a resistência à corrosão de revestimentos de carboneto de vanádio termodifundidos e aplicados por laser cladding sobre o aço ferramenta AISI D2. Os revestimentos foram caracterizados quimicamente por difração de Raios X. Para avaliar a resistência à corrosão utilizou-se técnicas eletroquímicas, como a espectroscopia de impedância eletroquímica (EIS) e, a análise da microestrutura foi realizada por microscopia eletrônica de varredura com sonda. Os resultados dos ensaios eletroquímicos mostraram que a camada de carboneto de vanádio pelo processo de laser cladding do aço AISI D2 apresentou resultado significativo à resistência à corrosão. No processamento via laser, a fusão, convecção e solidificação do pó de carboneto de vanádio (VC) e da superfície do substrato fazem com que o cromo presente no substrato seja distribuído uniformemente não só na camada de carboneto de vanádio por laser cladding (VCLC) como na região logo abaixo, na zona térmica afetada (ZTA) pelo aquecimento. A resistência a corrosão foi observada nas análises feitas por microscopia eletrônica de varredura quanto à homogeneidade da camada. As análises por dispersão de raios X (EDS) e por difração de raios X (DRX) apresentaram teores do elemento ferro em níveis reduzidos, adequados para a boa resistência à corrosão.

Abstract in English:

ABSTRACT The corrosion process in metals compromises the structure and operation of various materials used in daily life. Surface coatings and modifications that delay the evolution of the corrosive process are the most commonly used protection methods. Vanadium Carbide Thermo-diffusion Coatings (VCTD) have been developed to improve the performance and life of steel forming tools. In this work, we evaluated the corrosion resistance of vanadium carbide coatings produced by thermodiffusion and by laser cladding on tool steel AISI D2. The coatings were characterized by electrochemical techniques to evaluate the corrosion resistance, scanning electron microscopy with probe, for analysis of the microstructure and chemical composition followed by X-ray diffraction. The results of the electrochemical tests showed that the layer of vanadium carbide by the laser cladding process of AISI D2 steel presented better resistance to corrosion. In laser processing, the VC powder and substrate surface rapid melting and metallic elements diffusion causes the chromium present in the substrate to be uniformly distributed not only in the layer of layer but also in the region just below, in the affected thermal zone (ZTA) by heating. The high corrosion resistance was consistent with the analysis made by scanning electron microscopy on the homogeneity of the layer. X-ray energy dispersion and X-ray diffraction presented iron element contents at reduced levels, suitable for high corrosion resistance.

Abstract in English:

ABSTRACT This study presents a novel approach for synthesizing a highly efficient oxygen reduction reaction (ORR) catalyst derived from natural wool fibers through a one-step pyrolysis process. The resulting FeCo-carbon fiber composite exhibits a unique hierarchical structure with a BET surface area of 786 m2/g and a micropore volume of 0.31 cm3/g. X-ray photoelectron spectroscopy reveals significant nitrogen doping (6.4 at%) and the presence of catalytically active Fe and Co species. In alkaline medium, the catalyst demonstrates exceptional ORR performance with an onset potential of 0.98 V and a half-wave potential of 0.85 V vs. RHE. The material achieves a limiting current density of 5.8 mA/cm2 and an electron transfer number of 3.92, indicating a predominant four-electron pathway. Notably, the catalyst retains 92% of its initial current density after 20 hours of continuous operation and exhibits superior methanol tolerance. In acidic medium, the catalyst maintains promising activity with an onset potential of 0.83 V and a half-wave potential of 0.72 V vs. RHE. The synergistic effects of FeCo alloy nanoparticles, nitrogen-doped carbon, and a partially graphitized structure contribute to the material’s outstanding catalytic properties. This work not only introduces a sustainable and cost-effective approach to ORR catalyst synthesis but also highlights the potential of animal-derived biomass in developing high-performance electrocatalysts for energy conversion applications.

Abstract in English:

ABSTRACT This work models numerically the concrete mechanical behaviour using a two-dimensional model at mesoscopic level and using the concept of Representative Volume Element (RVE). Concrete is considered as three phases material: mortar/aggregate interface, mortar matrix and aggregate zones, where each constituent is modelled properly. The aggregates are considered to behave elastically, while the Mohr-Coulomb criterion defines the mechanical behaviour in the mortar matrix. Different strategies are used to model the fracture process at the interface transition zone: i) defining rectangular finite elements along interfaces where a fracture/contact model is incorporated; ii) adopting triangular finite elements where the Mohr-Coulomb model is used with lower strength characteristics compared to the mortar matrix. In the numerical examples, we study which of these two strategies is more efficient for modelling the transition zone. Besides, in the RVEs we consider different shapes for the aggregates, which are randomly arranged, with different volume fractions. The results evidence the potentialities of the proposed modelling, but they also show the high sensibility of parameters related to fracture and contact models what can restrict their use for interface zone modelling.

Abstract in English:

ABSTRACT Electric Discharge Machining (EDM) is one of the most effective unconventional material removal techniques that mill electrically conductive objects, despite their hardness using electrical discharge. This elite method provides excellent accuracy and surface finish within short duration. The presented research envisages to study the effect of process variables of EDM namely Pulsating Current (I), Pulse-on-time (Ton) and Pulse-off time (Toff) on machining performance measures namely Tool Wear Rate (TWR), Surface Roughness (SR) and Material Removal Rate (MRR). The best possible condition for specimen selection is presented by a new technique known as Multi Attribute Recursive Optimization (MARO). The optimal experimental conditions were found with Ton 100 s, Toff 49.82 s, and I 4.99 A, with ideal responses of SR 0.057 µm, MRR 0.036 g/min, and TWR 3.301 g/min. For the best run identification, the METHod for Enrichment Evaluation, Preference Ranking Organization METHod (PROME-THEE) was used while Historical Data Design (HDD) was used to validate the result obtained. The integration of PROMETHEE and HDD known as MARO is identified to appreciate degree of the methods analyzed. The close convergence of PROMETHEE and HDD at 97% guarantees the accuracy of the proposed MARO technique.

Abstract in English:

ABSTRACT This study focuses on optimizing and predicting the drilling performance of Fiber Metal Laminates (FMLs) reinforced with BaSO4 nanoparticles, achieved by adjusting parameters like spindle speed, feed rate, and tool diameter. Key responses—thrust force, torque, delamination, and surface roughness—were evaluated to enhance machinability. Using Central Composite Design, optimal parameters were identified: a spindle speed of 3000 rpm, feed rate of 10 mm/min, and tool diameter of 6 mm. Under these conditions, thrust force decreased by 51.92%, surface roughness improved to Ra = 2.3 µm, and delamination reduced by 21%. A two-layer feed-forward neural network in MATLAB 2023a accurately predicted outcomes with a Mean Square Error (MSE) of 1.4025e-05, demonstrating high correlation with experimental data. The inclusion of BaSO4 nanoparticles significantly improved the FMLs’ mechanical and thermal properties, enhancing machinability. This integrated approach of experimental optimization and predictive modeling provides a strong framework for precision machining of hybrid composites. The findings are especially promising for aerospace and automotive industries, where defect-free, high-quality FML machining is essential, positioning this method as a key advancement in nanoparticle-reinforced composite drilling.

Abstract in English:

ABSTRACT Air pollution is a critical environmental problem driven by urbanization and industrialization. Time-series forecasting using previous methods is difficult because models must account for seasonal changes, day-to-day changes, and emergencies that can rapidly affect air quality. Therefore, existing approaches struggle to predict these fluctuations. This research addresses this issue by proposing a material-focused method of air quality prediction using machine learning techniques. The proposed model incorporates feature selection using MS-ANFIS-FS and classification using Unet-RNN (Unet Optimized Recurrent Neural Network). The model focuses on analyzing pollutant interactions with material surfaces, improving prediction accuracy by considering the role of materials in pollutant dispersion and absorption. The Successive Feature Defect Scaling Rate (SFDSR) and Auto-Regressive Integrated Moving Average (ARIMA) methods detect variance dependencies in air quality data. These methods enable the model to identify material traits influencing pollution levels, yielding more accurate results for pollutants like PM2.5 and NO2. The findings demonstrate the critical importance of material properties in environmental management and show how material-based interventions can effectively reduce air pollution. This model has the potential to facilitate real-time pollution monitoring and support the development of sustainable air quality management strategies.

Abstract in English:

ABSTRACT This study examined the behavior of two-span continuous beams reinforced with Engineered Cementitious Composite (ECC) under static loads, showcasing ECC’s significant ability to enhance the flexural strength, durability, and overall resilience of conventional concrete structures. The research focused on assessing how ECC layers contribute to the structural integrity, load-bearing capacity, and crack development of the beams, utilizing a mix of materials including Ordinary portland cement (OPC) 43 Grade, fly ash, manufactured sand, polypropylene fibers, silica fume, superplasticizer, water, and coarse aggregates. The flexural tests indicated that replacing traditional concrete with ECC led to substantial improvements in load-carrying capacity and ductility, with ECC’s unique properties resulting in reduced crack widths and spacing in tension zones. Additionally, the study highlighted ECC’s advantages in terms of energy absorption and post-cracking behavior, suggesting that beams with ECC could exhibit longer service life and lower maintenance requirements. The integration of ECC also enhanced protection for the longitudinal reinforcement, indicating its potential for use in seismic-resistant designs and other high-performance applications. Overall, the findings underscore ECC’s transformative role in improving the performance and sustainability of concrete structures in modern engineering.

Abstract in English:

ABSTRACT This study recommended a micro-surfacing cold-mix binder with good water stability, high- and low-temperature property and fast curing rate. Additionally, a dynamic water disturbance experiment method to evaluate the adhesion of composite modified emulsified asphalt was developed. Initially, the optimal SBR content is determined through performance tests, followed by selected a suitable WER system via film-forming experiments. Various WER-SBR composite-modified emulsified asphalt formulations are prepared by adjusting WER concentrations. The properties of WER-SBR modified emulsified asphalt were comprehensively evaluated using methods including penetration, softening point, ductility, Brookfield viscosity, storage stability, dynamic water disturbance experiment, dynamic shear rheometer, scanning electron microscopy, and fluorescence microscopy, and the appropriate range of WER content was discussed. The results of the study showed that when the SBR content was 3%, the comprehensive performance of the modified emulsified asphalt was optimal. The addition of WER could improved the high-temperature performance and adhesion of SBR modified emulsified asphalt, but it gradually weakened the low-temperature performance and storage stability. Based on the comprehensive evaluation of the experiments, if the modified emulsified asphalt is for immediate use, the recommended WER content is 6%–9%. If the modified emulsified asphalt needs to be stored for one day, the recommended WER content is below 4%.

Abstract in English:

ABSTRACT Handheld electronic devices are vulnerable to drop impacts, leading to mechanical damage and electrical failures such as PCB cracking, trace damage, solder joint fractures, and component breakage. This study investigates the reliability of solder joints in Ball Grid Array (BGA) packages by examining their dynamic response under board-level drop impacts using Finite Element methods. Explicit dynamic analysis employing the Input-G method, in accordance with JEDEC guidelines, was used to simulate the printed circuit board assembly (PCBA) model. Results reveal that solder balls on the board side are more critical than those on the package side, with corner-most solder balls near the board edges identified as the most vulnerable, experiencing maximum peel stress of 162.12 MPa and strain of 0.001048. Analysis of radial displacement and drop orientation showed that BGA packages positioned closer to PCB edges exhibit greater reliability than those at the centre. The face-down drop orientation was identified as the most vulnerable configuration. Structural optimization of the PCBA, incorporating factors such as solder ball pitch, PCB thickness, and solder ball diameter, significantly improves reliability, underscoring the importance of these parameters in ensuring the long-term durability of the assembly.

Abstract in Portuguese:

RESUMO O objetivo da pesquisa foi avaliar as propriedades físicas e mecânicas de blocos intertravados para pavimentos com a incorporação de casca de arroz in natura em sua composição. Foram adotadas as proporções de 0%, 5%, 10%, 15% e 20% de casca de arroz em relação à massa seca do cimento. Após a cura os blocos foram realizados: inspeção visual, avaliação dimensional, absorção de água, resistência à compressão e densidade. Os blocos produzidos com 20% apresentaram elevada fragilidade. Para os demais blocos com casca de arroz observou-se alterações das peças através do surgimento de espaços vazios e falhas nas arestas dos blocos. A incorporação da casca de arroz não modificou a resposta dimensional dos blocos, com valores de Índice de Forma compatíveis com os vigentes na norma. Considerando os tratamentos com adição da casca de arroz, o melhor desempenho para os parâmetros de absorção de água, resistência à compressão e densidade foi verificado com a incorporação de 5% de casca de arroz nas peças. Sugere-se expandir estudos para aprimorar tratamentos físicos e químicos na casca de arroz in natura, a fim de compreender melhor suas propriedades e utilização como reforço em compostos cimentícios.

Abstract in English:

ABSTRACT The research objective was to evaluate the physical and mechanical properties of paving blocks after incorporating raw rice husks into their composition. The proportions of 0%, 5%, 10%, 15% and 20% rice husk in relation to the dry mass of the cement were adopted. After curing, the pavers were subjected to visual inspection, dimensional evaluation, water absorption, compressive strength and density. The blocks produced with 20% showed high fragility. For the other pavers with rice husk, changes in the pieces were observed through the appearance of empty spaces and flaws on the edges of the blocks. Incorporating the rice husk did not modify the dimensional response of the blocks, with Shape Index values compatible with those in force in the standard. Considering the treatments with adding rice husk, the best performance for water absorption, compressive strength, and density was verified by incorporating 5% rice husk in the pieces. It is suggested to expand studies to improve physical and chemical treatments of rice husk in nature to better understand its properties and use as reinforcement in cementitious compounds.

Abstract in English:

ABSTRACT Lead is a hazardous heavy metal known for its severe health impacts, including its association with cancer. In this study, copper-doped activated carbon was synthesized using copper acetate and bean husk, activated chemically through potassium hydroxide (KOH). The data was fitted by the Langmuir isotherm model more accurately than by any other isotherm, and the adsorption capacity of Cu-AC nanoparticles was found to be 94.339 mg/g. For the removal of lead ions over Cu-AC nano-adsorbent, when comparing the values of qe calculated and qe experimental. Activated copper doped carbon has the capacity to operate as an adsorbent in the treatment of lead metal ion pollution and other associated heavy metal ion pollutants. Surface chemistry analysis identified hydroxyl, amino, aromatic, and carbonyl functional groups. Field emission scanning electron microscopy revealed interconnected mesoporous structures with numerous open pores. Adsorption experiments demonstrated that the sorption process aligned. The maximum adsorption capacity was recorded at 94.339 mg/g, with a significant desorption efficiency using HCl as the desorbing agent. Thermodynamic analysis confirmed that the lead ion removal occurred primarily through a physisorption mechanism.

Abstract in English:

ABSTRACT In this paper, the bonding properties between rebar and polyurethane concrete (PC) through pull-out tests of PC and rebar is investigated. The effect parameters such as the protective layer thickness of the specimen, the anchorage length of the rebar, the diameter and shape of the rebar on the bonding performance were considered separately. It was shown that the thickness of the protective layer significantly affects the bond strength between the rebar and the PC, and the bond strength increases with the increase of the thickness of the protective layer. The average bond stress is 12.36 MPa for a protective layer thickness of 45 mm, which is an increase of 17.55% compared to 35 mm. The average bond stress is 16.45 MPa at a protective layer thickness of 65, which is a 54.03% increase in stress from 35 mm. The bond strength of rebar to PC decreases with increasing diameter for the same anchorage conditions. The bond stress between the same diameter bars and PC for different anchorage lengths decreases with increasing anchorage length. When the diameter of the rebar is 22 mm, the bond stress between the rebar and the PC is 13.7 MPa, which is a 24.10% reduction in stress compared to 14 mm. The bond strength of rebar to PC decreases with increasing diameter for the same anchorage conditions. And the bond strength of ribbed bars is significantly higher than that of bare round bars. The research results can lay a foundation for the engineering application of polyurethane reinforced concrete.

Abstract in English:

ABSTRACT A copper – graphene base composite is developed with different hard particle reinforcements through the powder metallurgy process. The different reinforcement particles are silicon carbide (SiC), titanium carbide (TiC), zirconium oxide (ZrO2) and aluminum – magnesium (AlMg) at equal weight percentages. The spherical copper powder with irregular reinforcement particles got pressed during the powder compaction and deformed to form a strong structure. During sintering the powder compaction has undergone metallurgical diffusion and the bonding between the reinforcement and matrix material. The microstructure of the pure copper and the copper – graphene with different reinforcement is compared for discussion. The hardness of copper and copper – graphene – titanium carbide composite is maximum and similar in results. The density of copper – graphene – titanium carbide composite is two-fold harder than the copper – graphene – aluminum magnesium composite material. Subsequently the porosity of the AlMg reinforcement is less as the diffusivity is higher than the other reinforcements.

Abstract in English:

ABSTRACT This study develops an IoT-based real-time framework for monitoring concrete strength in structural frameworks, utilizing electrochemical and fiber optic sensors to enhance construction quality control and structural health monitoring. Accurate assessment of concrete strength is vital for ensuring the safety and longevity of infrastructure. Traditional testing methods, which are periodic and invasive, often fail to provide timely data on strength progression. This framework overcomes these limitations by enabling continuous, in-situ monitoring. Electrochemical sensors measure variations in the chemical environment of concrete, which correlate with strength development. Simultaneously, fiber optic sensors monitor strain and temperature changes, providing real-time insights into structural responses under load. The data collected by these sensors are analysed using the Plowman method and regression curve analysis, offering high precision in detecting early-stage strength development and modelling its progression over time. The system incorporates wireless data transmission to a central cloud-based server for storage, processing, and visualization. This approach ensures enhanced lifecycle management and resilience of infrastructures. By demonstrating the efficacy of this IoT-based monitoring system, the study underscores its potential to revolutionize construction practices. It provides a robust solution for real-time quality assurance, structural health monitoring, sustainable lifecycle management, and resilient infrastructures.

Abstract in English:

Abstract The study aims the performance of presoaked light expanded clay aggregate (LECA) and fly ash aggregate (FAA) as partial replacement of river sand in self compacting concrete (SCC). On a volume basis, presoaked LECA and FAA partially replace river sand. LECA and FAA are presoaked for 24 hours before casting of SCC. The water retained in the lightweight aggregates (LWAs) pores acts as an internal curing reservoir. SCC workability characteristics, including as flowability, filling and passing capabilities, resistance to segregation, and concrete bleeding, were evaluated using slump cones, U-boxes, L-boxes, V-Funnels, and J-ring tests. Addition of LECA and FAA reduces the water for curing and also attain good workability and strength of SCC. The durability characteristics such as sulphate attack, acid attack are conducted in various durations like 7, 28, 56, 90, 180 days. Further, bond strength and accelerated corrosion tests also conducted. From all the mechanical and durability tests on SCC with LECA and FAA by 15% replacement for fine aggregate shows more beneficial effect in strength, microstructural and durability properties than those demonstrated by control mix concrete.

Abstract in English:

ABSTRACT A heat pipe with low thermal resistance and high thermal conductance is one of the most effective heat transfer devices. It can move large amounts of heat over a small cross-sectional area with extremely little temperature variations between the two temperature limits. This study uses Design of Expert software to evaluate the performance of various nanofluids as the working fluid for the heat pipe, including copper oxide, graphene oxide, iron oxide, and titanium oxide. The base fluid used in this analysis is an aqueous solution of n-Octanol. The parameters considered in this analysis are the condenser flow rate, filling ratio, angle of inclination, and heat input. In order to assess the thermal efficiency of the heat pipe's working fluids, all operational factors are assessed using the Central Composite Design (CCD) matrix and Response Surface Methodology during experiment design. The experimental findings demonstrate that the suggested model can predict the heat pipe's thermal efficiency to within 1% of the variation. As a result, the suggested model can be used to forecast the heat pipe's thermal efficiency.

Abstract in English:

ABSTRACT This study presents an investigation into the challenge of alleviating heavy metal pollution while using red mud (RM) as an industrial byproduct, focusing on its application in the preparation of geopolymers. Synthesis RM-ground granulated blast furnace slag (GGBS)-based geopolymer (RMG) and studied with particular attention to optimizing compressive strength through modifying key parameters: RM content, Na2SiO3 modulus, and water-to-binder ratio. The immobilization of heavy metals, particularly lead (Pb) and copper (Cu), within geopolymer was thoroughly examined. Results indicate that optimal compressive strength was achieved at a 40 wt.% RM content, a Na2SiO3 modulus of 1.8, and a water-to-binder ratio of 0.65, with 28-day compressive strengths reaching 36.9 MPa. A 1% mass of heavy metals was observed to improve the mechanical characteristics of the geopolymer; however, beyond this threshold resulted in detrimental effects. The immobilization capabilities of RMG under various environmental conditions were robust, with immobilization efficiencies exceeding 97% for Pb and 94% for Cu. The immobilization mechanism was found to involve physical encapsulation, with Cu uniquely forming covalent bonds with non-bridging oxygens within the polymeric structure, creating stable Si-O-Cu bonds. This study highlights the potential of geopolymer as a viable technology for mitigating environmental impacts associated with RM disposal by effectively immobilizing heavy metals, thus facilitating safe and sustainable resource utilization. This work contributes to the field by demonstrating a novel approach to the valorization of industrial waste, offering a promising solution for the management of RM while addressing the critical issue of heavy metal pollution.

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ABSTRACT This study investigates how the workability and mechanical qualities of concrete are affected by adding different amounts of Ordinary Portland Cement (OPC), Ground Granulated Blast Furnace Slag (GGBS), Fine Aggregate (FA), Coarse Aggregate (CA), and Lightweight Expanded Clay Aggregate (LECA). Traditional coarse aggregates were replaced with GGBS ranging from 5% to 20% and LECA included at varying degrees in a range of concrete mixtures. Slump, L-box, V-funnel, J-ring, and U-box tests were used to evaluate workability, while tests for compressive strength, split tensile strength, and flexural strength were used to evaluate mechanical characteristics at 7, 14, and 28 days. The results showed that workability and compressive strength increased with increasing GGBS concentration, with 15% GGBS achieving a maximum of 68.34 MPa. However, higher proportions of LECA negatively impacted mechanical strength. The optimal mix comprised 85% OPC, 15% GGBS, and a balanced LECA content, achieving enhanced workability without compromising strength. This research highlights the potential for sustainable concrete production by utilizing waste materials while ensuring structural integrity.

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ABSTRACT Micro/meso fabrication techniques have gained significant recognition globally for their advanced manufacturing capabilities. Among these, microforming stands out as a leading process in micromanufacturing. Despite growing interest in microextrusion for industrial applications, the technology remains underdeveloped compared to conventional forming methods, with limited expertise available. To address this gap, it is essential to develop a comprehensive understanding of the microextrusion process, which can guide the production of metallic microcomponents. This research focuses on the numerical simulation of microextrusion to study the influence of die entry angles on the deformation behavior of AA6063 aluminum alloy. Simulations were conducted using die angles of 15°, 30°, 45°, and 60° under varying frictional conditions. Results show a direct relationship between die angle and forming load, while punch displacement decreases as the die angle increases. The role of friction was also found to be crucial in the extrusion process. Numerical results for the 30° die angle were compared with experimental data, highlighting the effectiveness of finite element analysis in predicting microforming outcomes. This study demonstrates the potential of numerical simulation as a powerful tool for optimizing microforming processes in industrial applications.

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ABSTRACT This research paper aims to develop hybrid fibre-reinforced Engineered Cementitious Composites (ECC) deploying different modulus of fibre and to explore the mechanical and flexural response of newly refined Hybrid ECC in the 30 mm thick bottom layer of reinforced concrete (RC) beams. This investigation uses five combinations in the RC beam. The focus of hybridization is to increase the flexural response and structural functioning of RC beams. ECC mixes were attempted with the deployment of Polyvinyl Alcohol (PVA) Fibre and Polypropylene (PP) fibre with 2% as a mono fibremix. Hybridization is made with 0.65% of PVA and 1.35% of PP, 1% of PVA and 1% of PP, 1.35% of PVA, and 0.65% of PP. In this research investigation, mono fibre ECC with 2.0 % PVA fibre mix was taken as a base mix for comparison. From the behavior of the beam, it was found that the mix with PVA fibre of 1.35% hybrid with PP fibre of 0.65% exhibited better performance in flexural when compared with conventional concrete. However, PP fibre of 2% volume fraction has high energy absorption capacity, and PVA fibre of 2% volume fraction has high ductile displacement compared to conventional concrete.

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ABSTRACT The consequences of partially substituting electronic trash (e-waste) for traditional aggregates in concrete compositions are examined in this study. When compared to conventional mixes, the testing findings show that adding e-waste improves the mechanical qualities and durability of concrete. Specifically, compressive strength peaked at 30.19 MPa for the mix containing 12% e-waste, significantly surpassing the conventional concrete's strength of 25.21 MPa. Improvements were also observed in split tensile and flexural strengths, with maximum values of 2.00 MPa and 2.64 MPa, respectively. The modified concrete showed reduced water absorption and porosity, indicating enhanced durability. Notably, the resistance to sulfuric acid attack improved, with the lowest weight loss (5.52%) and strength loss (6.39%) recorded in the e-waste mix. These findings affirm that utilizing e-waste in concrete not only contributes to superior mechanical performance but also enhances resistance to environmental challenges. This research promotes the sustainable use of e-waste in construction, supporting eco-friendly practices and effective waste management strategies.

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ABSTRACT Natural sand is a crucial ingredient that is used in cement planning and is also crucial to mix design. This paper examines the fundamental characteristics of concrete that contains both full and partial replacements of natural sand with manufactured sand (M-Sand). In this study, an attempt is made to preserve natural resources like natural sand by partially substituting M-Sand for natural sand. In order to examine the intrinsic characteristics of strength and durability in concrete, samples designated as M1CC, M2CM, M3CSMS, M4CSRS, M5SSRS, and M6SSMS were selected for analysis. A series of experimental assessments were performed to evaluate the compressive strength, split tensile strength, and flexural strength of both conventional concrete and M-Sand concrete within the context of the strength characteristic evaluation. The durability analysis of both conventional and M-Sand concrete was conducted utilizing the sulphate attack test, Acid Attack Test, and the Rapid Chloride Permeability Test (RCPT). Experimental results revealed that concrete with 60% replacement of natural sand by M-Sand exhibited a 20% increase in compressive strength compared to conventional concrete. Durability tests showed a reduction in chloride ion penetration by 25%, and better resistance to acid and sulfate attacks in M-Sand concrete. Morphological analysis indicated that M1CC had higher initial and secondary absorption compared to other specimens, while Scanning Electron Microscopy (SEM) analysis confirmed enhanced microstructural integrity in specimens with optimal M-Sand replacement. These findings demonstrate that partial substitution of natural sand with M-Sand can effectively improve both the strength and durability of concrete.

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ABSTRACT The proposed work presents an approach using different computational intelligence techniques combined with an evolutionary algorithm to predict the mechanical properties of lightweight aggregate concrete. Four regression techniques were used to make it possible to predict properties: multiple-layer artificial neural networks (ANN), support vector machines (SVM), extreme learning machines (ELM), and decision trees (DT), combined with an evolutionary optimisation algorithm, the particle swarm optimisation (PSO) algorithm. For the entire search process, the decision tree had the lowest average execution time, followed by ELM, which also had a low execution time. ANN and SVM obtained a very high average time and standard deviation compared to the other two methods tested. This is due to the different settings used in the search process, such as the number of layers for the ANN and the precision parameter ε of the SVM, which can lead to a drastic change in the learning time of these methods. In contrast, ELM and DT have more stable behaviour in relation to execution time, regardless of the values of the tested parameters. This shows that SVM and ANN are very sensitive to the values used in their parameters in relation to execution time.

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ABSTRACT The present study monitored the rutting behavior of SBS-modified binders from three different crude oil sources, as well as their corresponding mixtures. Three formulations from Brazil and Russia were considered, one of which is a Brazilian highly-modified binder (SMB HiMA) and the other two are conventional SBS-modified materials (Brazilian SMB 60/85 and Russian SMB 65/90). The unmodified materials are from Brazil (AC 50–70) and Colombia (AC 60–70). Binder tests included oscillatory shear and MSCR – especially at the temperature of 64°C – and mixture tests included Flow Number (FN) at 60°C and Hamburg Wheel Tracking Test (HWTT) at 50°C. Out of the binder parameters evaluated here, the nonrecoverable creep compliance at 3.2 kPa (Jnr3.2) and the combined elastic plastic parameter at 3.2 kPa (CEP3.2) showed more similarities with the rankings of mixtures and the highest correlations with FN and HWTT data. Conversely, the percent difference in nonrecoverable compliances (Jnr,diff) poorly matched the mixture rankings, and it also depicted a diametrically opposite pattern of response in the regression trendlines. The findings of the percent slope between the nonrecoverable compliances (Jnr,slope) are more promising than the ones of Jnr,diff, which is in agreement with the literature.

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ABSTRACT Self-Compacting Concrete (SCC) is a very flexible concrete that flows through intricate, heavily reinforced structural components and compacts under its own weight. Natural sand is in extremely high demand in developing countries because of the rapid expansion of the infrastructure. Many researchers are substituting some of the fine aggregate with materials based on slag. Environmental contamination is increased by the production of casting slag, a by-product of the casting industries that can be used to make concrete. Casting slag is a coagulation process result that is a solid in the iron industry. After being identified as garbage, it is usually disposed of in the utility disposal site. As a result, an effort has been undertaken to assess how casting slag affects the amount of Fine Aggregate (FA) replacement in the percentage of be 0%, 10%, 20%, and 30% and abovementioned tests were conducted. The results of the tests demonstrated that casting slag may be utilized efficiently as a substitute in part for fine aggregate in self-compacting concrete, resulting in sustainable construction.

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ABSTRACT Utilization of Nano-structure pyrolytic carbon (NSPC) particles holds significant potential in developing nanocomposites. Consequently, compressive strength is a crucial characteristic which stipulates the efficiency of NSPC particles in cementitious composites. Nevertheless, predicting the compressive strength of this nanocomposite is a significant challenge due to distorted responses and complex structures. The main novelty of this research is to predict the compressive strength of the developed NSPC nanocomposite. Therefore, the machine learning (ML) model is the first-time proposed for predicting the compressive strength of nanocomposite mortar incorporated with various dosages of NSPC particles. In addition, the bound water of the nanocomposite mortar is determined to understand the efficiency of NSPC particles in the hydration process. This work highlights a comprehensive comparison of six ML algorithms, such as linear regression, random forest regression, extra trees, gradient boost regressor, extreme gradient boost, and LightGBM, for prediction accuracy of compressive strength of NSPC nanocomposites. Furthermore, it is evaluated through multiple statistical error analysis. Seventeen parameters were considered input variables to predict the compressive strength of nanocomposite mortar. According to the coefficient of determination analysis, the gradient boost regressor model attained the highest R2 value of 0.87, while the extreme gradient boost and extra trees achieved R2 values of 0.86 and 0.85, respectively. In addition, a low mean absolute error of 3.229 was earned for the extreme gradient boost. Overall, the gradient boost regressor was reliable and performed better in predicting the compressive strength and mapping the interplay between input variables and compressive strength.

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ABSTRACT This study examines how adding fly ash and silica fume to concrete affects its durability and mechanical qualities. Ten concrete mixtures in all, including a traditional concrete mix and several fly ash and silica fume combinations, were assessed. Compressive strength, split tensile strength, permeability, sorptivity, RCPT, and ultrasonic pulse ve-locity (UPV) at various curing ages (7, 14, and 28 days) were among the performance parameters examined. According to the results, at 28 days, ordinary concrete had the maximum compressive strength, measuring 29.66 MPa. The 10% fly ash and 10% silica fume (S6) combination produced the best results among the adjusted mixes, with a com-pressive strength of 32.55 MPa and a split tensile strength of 2.33 MPa. Additionally, the investigation showed that all of the blends had minimal permeability, which suggests strong durability properties. All things considered, adding more cementitious ingredients can improve the qualities of concrete, but the ratios employed are crucial for maximizing results. The results highlight how fly ash and silica fume may be added to concrete com-positions to increase sustainability without compromising structural integrity.

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ABSTRACT A double-fed induction generator (DFIG) based wind energy conversion system (WECS) has been proven to be an efficient solution for electrical energy generation from wind. In this paper, the design process of cascade control loops for the implementation of a maximum power point tracking (MPPT) control algorithm on a DFIG-based WECS is presented. A tip speed ratio algorithm (TSR) was chosen in this work to generate reference turbine speed signals for harvesting maximum energy from all wind profiles. The design methodology of cascade controllers for the power electronics converter is explained in detail in this work and the performance of the system in extracting maximum power from wind is evaluated using Matlab/Simulink simulation tool. The simulation results are proved that the tuned controllers are able to operate the wind energy conversion system at maximum power point in extracting maximum energy from all types of wind profiles.

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ABSTRACT Abrasive water jet machining produces large quantities of spent abrasive particles, typically discarded due to their heterogeneous composition, comprising both metallic and non-metallic components that vary with the processed material. However, these particles can be repurposed for engineering applications. This study utilized spent abrasive particles as filler materials at 2.5%, 5%, and 7.5% by weight in an epoxy resin matrix to fabricate kenaf fiber-reinforced hybrid polymer composites. The tribological properties of the composites were systematically analyzed to identify optimal conditions for minimizing wear rate and friction. Pin-on-disc wear tests were performed using a standard tribometer at sliding velocities of 1 m/s, 2 m/s, and 3 m/s, under loads of 5 N, 10 N, and 15 N, over a constant sliding distance of 800 m. Results showed a minimum wear rate of 0.0108 mm3/m and a minimum coefficient of friction of 0.0581 for composites with 7.5 wt.% filler at a 5 N load and 1 m/s sliding velocity. Worn samples were examined using scanning electron microscopy to explore the dominant wear mechanism. The inclusion of spent abrasive particles significantly improved tribological performance by enhancing wear resistance and modifying frictional behavior through improved interfacial bonding in the polymer matrix.

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ABSTRACT Ti15Mo alloys have recently been attracted in biomaterials due to its favourable mechanical and biocompatibility properties. However, the wear resistance of this alloys should be improved for dental applications. The objective of this in vitro study was to investigate the effects of a TiN film on two-body wear properties of the Ti15Mo alloy. The microstructure properties of uncoated and TiN film-coated alloys were comparatively investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray spectroscopy (EDS), and microhardness measurement systems. The wear performance of uncoated and coated samples has also been evaluated using a dual-axis computer-controlled wear simulator device in distilled water. Following the completion of the two-body wear test procedures, the mean wear volume loss of all test samples was determined utilising a non-contact 2D and 3D profilometer. The two-body wear resistance of TiN film-coated alloys was superior to that of the uncoated alloys. The coated samples exhibited enhanced wear resistance, which was accompanied by an increase in hardness and a reduction in surface roughness. The mean wear volume loss of coated samples was lower than the other group samples irrespective of test conditions.

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ABSTRACT This study evaluates the performance of an enhanced indirect solar dryer with integrated thermal storage for drying apple slices efficiently, offering a practical solution for sustainable post-harvest management. The dryer features a single-pass solar collector and a 16.5 kg capacity drying chamber embedded with paraffin wax as a thermal energy storage material to maintain consistent heat during the drying process. This innovative design achieved a thermal efficiency 11 ± 0.2% higher than conventional solar dryers and reduced drying time by 40 ± 2.1%, aligning with the goals of energy-efficient post-harvest practices. Compared to open sun drying and thin-layer drying, the solar dryer with thermal storage (SDTS) preserved nutrients more effectively, with total sugar content reaching 64.85 ± 3.50% and fiber content at 12.50 ± 0.75%, the highest among all methods. Moreover, SDTS-dried apple slices exhibited greater total phenolic content (TPC) and antioxidant activity, underscoring superior product quality. The integration of thermal storage minimized drying inconsistencies, reducing post-harvest losses and ensuring nutrient retention. Statistical models were developed to predict moisture ratios accurately, validated through chi-square and root mean square error analysis. This enhanced dryer demonstrates improved efficiency and reliability, making it a scalable, sustainable solution for small-scale fruit farmers, ultimately addressing critical post-harvest management challenges.

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ABSTRACT Oxygen vacancies in magnetic materials are pivotal in tailoring their magnetic properties, offering a versatile pathway to manipulate their performance. This study focuses on the impact of oxygen vacancies on the magnetic properties of EuTiO3 (ETO) thin films, demonstrating how these vacancies can induce ferromagnetism, a property not typically observed in its stoichiometric form. By controlling the background oxygen pressure during fabrication, we obtained ETO thin films with varying concentrations of oxygen vacancies and investigated their magnetic behavior. The results reveal that the manipulation of oxygen vacancies significantly influences the magnetic properties of ETO thin films. Films grown under low oxygen pressure exhibit a peak in the Curie temperature (Tc) around 4.1 K, indicating a transition to a ferromagnetic state. In contrast, films grown under high oxygen pressure show a Tc peak at approximately 2.5 K, suggesting an antiferromagnetic state. The control over oxygen vacancies provides a profound impact on the magnetic landscape of ETO, making it a critical handle in the engineering of magnetic properties for various applications, including multiferroic devices.

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ABSTRACT The performance of polymer-based nano iron composites reinforced with natural fibers and nanoparticles is investigated in this work with the aim of enhancing their mechanical electrical and water-absorbing properties for a variety of applications. System 1 (PLA with nano iron particles) System 2 (PLA with natural fillers) and System 3 (PLA with both natural fillers and nano iron particles) are the three composite systems that were developed. Mechanical performance assessment tests including tensile compression and bending tests as well as electrical conductivity and water absorption morphological analysis using SEM and EDAX were all conducted. According to the results System 3 which combines natural fillers with nano iron showed superior tensile and flexural strength because of improved filler dispersion and improved filler-matrix bonding. The creation of a conductive network by nano iron was responsible for System 2s highest electrical conductivity (340 µS/cm). Compression testing showed that Systems 2 and 3 were stronger because there were fewer voids and cracks spreading. System 2 did however exhibit a high water absorption rate of 20% which may indicate durability problems. According to this study adding natural fibers and nanoparticles to PLA composites may produce lightweight incredibly durable multifunctional materials with exciting potential uses in the electronics automotive and construction sectors.

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Abstract In the realm of compression molding of Carbon Fibre Reinforced Composite (CFRC) laminates, pivotal technological challenges related to product quality monitoring are addressed in this study, a multi-source information fusion method based on monitoring feedback is proposed. The study begins with the design of a control system, alongside the establishment of its software and hardware architecture, all of which are rooted in the production line's composition, its processes, and the overarching manufacturing workflow. This paves the way for the refinement and optimization of reliability assessment methods, specifically tailored for monitoring factors and characteristics with functionalization at their core. Then, a higher-order shear deformation theory (HSDT) is proposed based on Iso-Geometric Analysis (IGA), and the static bending, free vibration, and buckling behaviours of CFRC laminates are scrutinized. The narrative culminates under the influence of fluctuating temperature conditions, where the proposed methodology's performance and precision are rigorously validated through an extensive suite of numerical examples. A comparative analysis with theoretical results gleaned from existing literatures yields a harmonious consistency, underscoring the robustness of the approach. The research results of this paper provide theoretical support for the quality analysis of carbon fiber reinforced composite molding process.

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ABSTRACT Self-Compacting Concrete (SCC) plays a vital role in the construction sector globally due to the requirements of tall and complex congested structures. River sand is one of the natural key ingredients that has high demand due to the expansion of cities and the growth of population. To overcome this problem researchers from various countries are attempting for alternative materials. In this research, Sugarcane Bagasse Ash Aggregates (SBAA) and Rice Husk Ash Aggregates (RHAA) were utilized to partially substitute of fine aggregate in SCC. The suitability of SBAA and RHAA in SCC is assessed by microstructural characterization and mechanical properties. Three groups of SCC mixes were prepared. Gropup-1 mix contains RHAA about (0%, 5%, 10%, 15% and 20%), Group-2 mix contains SBAA (0%, 5%, 10%, 15% and 20%) and Group-3 mix contains blended RHAA SBAA (each 5%, 10%, 15% and 20%). EFNARC guidelines were used for mix design and assess the rheological characteristics. In all the groups of SCC mixes, 10% replacement of SBAA and RHAA shows significant results. This investigations shows that the blended ash aggregates can be replaced with fine aggregate and considerably can reduce the demand of river sand.

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ABSTRACT This study investigated the optimal calcination conditions for obtaining β-hemihydrates from the “cocadinha” and “rapadura” varieties of gypsum, which are used in plaster production in the Araripe gypsum Pole. The samples were characterized using techniques such as scanning electron microscopy (SEM), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), and X-ray diffraction (XRD). The analyses indicated a similarity in the morphology of the samples. During calcination in a static furnace, mass losses ranging from 12.8% to 19.8% were observed. The study identified thermal events and crystalline phases as the calcination time and temperature varied. Complete conversion of the dihydrate phase into β-hemihydrate was achieved at 180 °C for 2 h, while partial conversion occurred at 160 °C for 2 h. The Rietveld refinement was successful, with χ2 values close to 1 and R indicators below 10% for all analyzed samples. Based on the experimental results, the study identified optimal calcination conditions for producing hemihydrate plaster from the cocadinha and rapadura gypsum varieties, achieving consistent hardness and compressive strength in accordance with NBR 13.207 standards. Both varieties demonstrated setting times comparable to industrial benchmarks after 2 hours or more of calcination at 160 °C and 180 °C. These findings suggest the potential for process optimization, reducing energy consumption while maintaining product quality.

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ABSTRACT Aluminium alloys find diverse applications in building construction. Specifically, C-profiles being used as various structural elements in the building. Providing Edge stiffeners in the C-profile leads to increase the load carrying capacity. Limited research is available on compression behaviour c-profile with edge stiffeners. Hence, this article aims to study the behaviour of a Finite Element Analysis of aluminium alloy stiffened edge C profiles subjected to axial compression. Two different aluminium alloy materials, namely 6061-T6, and 6063-T5 were investigated. Finite element models were developed and results, including ultimate load, failure modes, and load vs. axial shortening curves, were verified against existing test data. A comprehensive parametric study was carried out based on the verified finite element models, involving variation in the orientation of the edge stiffener, column length, and section thickness. A total of 144 parametric results were compared with the design strengths calculated from Euro code 9.

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ABSTRACT This study investigates the synthesis and application of a novel ZnO-polyacrylamide nanocomposite as a performance-enhancing additive for water-based drilling fluids. The nanocomposite was successfully synthesized through a modified solution polymerization method, producing uniformly dispersed spherical particles ranging from 35 to 45 nm as confirmed by FESEM analysis. XRD characterization revealed distinctive peaks at 2θ values of 31.7°, 34.4°, 36.2°, 47.5°, and 56.6°, confirming the hexagonal wurtzite structure of ZnO, while FTIR spectroscopy demonstrated effective integration through characteristic absorption bands at 3435 cm−1, 2924 cm−1, and 1656 cm−1. Systematic evaluation of drilling fluid properties showed that incorporation of the nanocomposite at concentrations between 0.1−1.0% (w/v) significantly enhanced performance parameters. The optimal concentration of 0.7 wt% achieved a 43.8% reduction in API fluid loss, decreased filter cake permeability by 62.4%, and maintained rheological stability with viscosity reduction rate of 0.15 cP/°C compared to 0.28 cP/°C for the base fluid. HTHP testing at 150°C and 500 psi demonstrated enhanced thermal stability with 35.5% reduction in filtrate volume. Shale inhibition studies revealed improved performance through both linear swelling tests and recovery measurements, with recovery rates remaining stable even after secondary exposure to fresh water. The research demonstrates that the integration of ZnO nanoparticles within a polyacrylamide matrix creates a synergistic effect that addresses multiple drilling fluid challenges simultaneously, offering potential applications in high-temperature wells and reactive shale formations.

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ABSTRACT The flow and heat transfer characteristics of methane under supercritical pressure are crucial for storing and transporting liquefied natural gas. This study employs a renormalization group k-ε model with enhanced wall functions to investigate methane’s mixed convective heat transfer in pipes with different diameters, revealing two heat transfer enhancement characteristics. When the channel diameter changes, the mechanisms influencing heat transfer performance differ, resulting in peaks of varying nature in the heat transfer curve. The enhanced heat transfer mechanisms are explained in detail by comparing the effects of buoyancy and specific heat capacity at various temperatures. Further analysis reveals that increasing heat flux leads to the superposition of buoyancy and specific heat effects, producing a single peak in the heat transfer coefficient. The relative variations of the Nusselt number and synergy angle explain the phenomenon of heat transfer enhancement superposition. A new criterion for enhanced heat transfer due to buoyancy is proposed, Bo* = 4.21 × 10−8, which can be used to evaluate the impact of buoyancy on the enhanced heat transfer.

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ABSTRACT Materials recycling presents a compelling economic case for waste disposal sites and the conservation of natural resources. This study delves into the substitution of cement with varying percentages of marble waste (0%, 10%, 20%, 30%, 40% and 50%). The water-to-binder ratio is consistently set at 0.44 for all mixes. Chemical admixtures such as superplasticizers or viscosity agents are frequently added to the mortar to improve its flow and strength. We conducted mini-slump flow and rheometer tests to assess the fresh mixes' rheological properties, as well as tests to measure the compressive and tensile strength of the mixes. The findings indicate that including marble powder enhances the mechanical properties of self-compacting mortar. A substantial 29% enhancement was achieved for a mixture incorporating 30% marble waste. The most favorable rheological properties, including slump flow, yield stress, and superior mechanical performance in compressive and tensile strength, were observed in the mix containing 30% marble powder waste. Furthermore, the investigation showed that the self-compacting mortar with a yield stress of 0.98 MPa at a 50% MW replacement rate and a viscosity of 1.4 Pa.S can achieve a slump flow of 25–31 cm. These findings illustrate marble waste potential as a valuable addition to self-compacting mortar (SCM) manufacturing, delivering improved performance and structural integrity. However, specific application scenarios and long-term endurance restrictions require further investigation. Practical effects include the possibility of developing inventive, sustainable, and economic SCM compositions, which will help to advance construction practices and sustainability. The social ramifications include reducing environmental impact and increasing resource efficiency in the construction industry.

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ABSTRACT Significant risks of corrosion and wear are associated with agricultural equipment’s continuous exposure to fertilizers harsh chemicals and moisture. These chemicals hasten the deterioration of metal components thereby decreasing the machinery’s operational lifespan and leading to physical harm such as surface cracks and holes. Utilizing efficient corrosion protection methods is crucial to lessening these adverse consequences. In order to solve this, the current study investigates a corrosion prevention technique that involves coating copper with stearic acid to produce a superhydrophobic surface. To create this protective coating copper samples were cleaned and then left to soak for 72 hours at room temperature in a stearic acid solution. Utilizing energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) post-treatment analysis of the copper surfaces revealed a notable improvement in corrosion and wear resistance. The development of a hydrophobic microstructure was validated by SEM images and the successful deposition of the stearic acid was indicated by an 88 percent increase in carbon content in the EDX results. The high anti-wettability of the coating was demonstrated by performance tests which included water bouncing jetting and self-cleaning assessments. This technique also offers an eco-friendly corrosion prevention solution because stearic acid comes from natural sources. The results highlight the potential of stearic acid coatings to decrease metal loss from corrosion and increase the useful life and efficiency of agricultural equipment.

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ABSTRACT This study investigates developing and characterizing a novel hybrid composite reinforced with Prosopis juliflora bark nanoparticles, Raffia fiber, and glass fiber embedded in a polyester resin matrix. The composite was fabricated using the resin transfer molding technique to ensure uniform fiber impregnation and nanoparticle dispersion. Mechanical tests revealed a tensile strength of 165 MPa, a flexural strength of 388 MPa, an impact strength of 4 J, a Shore D hardness of 42 RHN, and an interlaminar shear strength of 24 N/mm2, marking significant improvements of 35–40%, 25–30%, and 20% in tensile, flexural, and impact properties, respectively, compared to conventional composites. Thermogravimetric analysis showed enhanced thermal stability, with decomposition temperatures increasing by 15–20% due to the thermal shielding effect of nanoparticles. Scanning Electron Microscopy (SEM) confirmed uniform nanoparticle dispersion and strong fiber-matrix adhesion, contributing to the composite’s superior performance. The novelty of this research lies in the synergistic combination of natural and synthetic fibers with multifunctional nanoparticles, which optimizes mechanical and thermal properties while maintaining environmental sustainability. These hybrid composites, with their significant mechanical and thermal improvements, are a scientific achievement and a cost-effective solution for high-performance applications in automotive, structural, and aerospace industries, offering a sustainable alternative to traditional materials.

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ABSTRACT This study examines the impact of adding fly ash and metakaolin to different concrete mixes on workability, strength, and durability. Results showed that conventional concrete had a slump value of 101 mm. In contrast, the mix with 10% fly ash and 10% metakaolin achieved a slump value of 102 mm, suggesting improved workability with this combination. The compressive strength for this mix was notably the highest at 35.34 MPa after 28 days, demonstrating the effectiveness of the combination in improving strength. The split tensile strength and flexural strength also showed significant improvements, with values of 55.34 MPa and 4.47 MPa, respectively. Furthermore, water absorption tests revealed a saturated water absorption of 1.99% and porosity of 2.85% for the optimal mix, suggesting enhanced durability due to reduced permeability. These findings highlight that the strategic use of fly ash and metakaolin not only optimizes the mechanical properties of concrete but also enhances its durability characteristics, making the 10% fly ash and 10% metakaolin blend a promising alternative for sustainable concrete formulations in construction applications.

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ABSTRACT In this study, we show how to use Metal Inert Gas butt-welding to its full potential by optimising the geometry of the weld beads. The poor quality of welding, which is affected by several factors during the welding process, is a common cause of joint failure. Along with the rapid advancement of computer and automated technologies, new statistical methodologies for optimization and modeling have been developed. Due to them, traditional trial-and-error-based studies for efficiency and quality are no longer necessary. Experimental methods were developed to elucidate the numerical expression between the welding process parameters and the output variable. It Briefly outline the criteria used for comparison (e.g., surface finish, tensile strength, and hardness) and state the key finding, such as how specific process parameters (e.g., temperature and rolling speed) achieved optimal performance metrics. These parameters included welding current, welding speed, and arc voltage. Then, the weld bead geometry's performance was evaluated using a Taguchi technique, which takes into account bead height and bead width. We employ an Orthogonal array of L9 and analysis of variance (ANOVA) to learn about and enhance the welding properties of hot rolled carbon steel material. Confirming its efficacy in the analysis of weld bead height and bead width, conformations tests were conducted to compare predicted values with experimental values.

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ABSTRACT This research delves into the impact of incorporating nanomaterials into reinforced concrete beams on their corrosion resistance and mechanical properties. Various combinations of nanomaterials, such as nanosilica (NS) and nanoclay (NC), are introduced into the cement matrix to examine their effects on fresh and hardened concrete. Testing is conducted on specimens including cubes, prisms, and beams at intervals of 7, 14, and 28 days to assess compressive and flexural strengths. The aim is to ascertain how different percentages of nanomaterial replacements for cement influence the mechanical properties of concrete. The properties comparable to the conventional concrete and 20% of nano silica addition of the concrete. Additionally, the study investigates the corrosion resistance of reinforced concrete beams with nanomaterials. The specimens tested such as rapid chloride permeability testing, half-cell potential testing, and resistivity testing are employed to determine the corrosion resistance of the beams. It is anticipated that certain combinations of nanomaterials will enhance the mechanical properties of the concrete, thereby improving its resistance to corrosion. The findings of this research hold potential for enhancing the durability and longevity of reinforced concrete structures in various applications.

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ABSTRACT This study explores the use of Ground Nut Shell Ash (GNSA), Cashew Nut Shell Ash (CNSA), and Discarded Nylon Fiber (DNF) as supplementary materials in cement concrete to enhance sustainability. Mechanical properties such as compressive, tensile, and flexural strengths were analyzed for concrete mixtures with varying proportions of these materials. Results indicate that the optimal blend increased compressive strength by 15%, tensile strength by 10%, and flexural strength by 12% compared to conventional concrete. Improvements are attributed to the pozzolanic activity of the ashes and the reinforcing effect of nylon fibers. The compressive strength also showed significant gains at 7, 28, and 56 days of curing. Utilizing these waste products promotes environmental sustainability and reduces waste. This research demonstrates the potential of agro-industrial by-products and recycled fibers to produce eco-friendly concrete with enhanced mechanical properties. Further studies are recommended to assess the long-term durability and environmental impacts of these innovative composites.

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Abstract This study presents an improved technique that uses many machine-learning models to estimate the compressive strength of concrete. The goal of the project is to increase the precision of strength predictions based on the age and composition of concrete mixes. Cement, fly ash, water, superplasticizer, coarse and fine aggregate, and sample age are among the materials. Megapascals (MPa) are used to quantify compressive strength. To determine the connections between mix proportions, age, and strength, a variety of blends were examined. Machine learning techniques including Random Forest, XGBoost, AdaBoost, Bagging, Support Vector Regression, and Linear Regression were used. The efficiency of the model was assessed using performance indicators such as accuracy, R-squared (R2), Mean Absolute Error (MAE), and Mean Squared Error (MSE). With an MAE of 2.2, MSE of 10.5, R2 of 0.94, MAPE of 8.5, RMSE of 3.25, and accuracy of 0.92, XGBoost (optimized) performed the best. This model performed noticeably better than others, highlighting how machine learning may improve predictions of compressive strength and optimize the composition of concrete, thus promoting the fields of materials science and civil engineering.

Abstract in English:

ABSTRACT The ability of the electrical steels to amplify an externally applied magnetic field is due to a strong texture induced during secondary recrystallization, the step in which grains with Goss orientation nucleate in the primary matrix. At this stage, normal grain growth is inhibited by a scattering of precipitated particles. The main objective of this research was to investigate the effect of stretching during the annealing and decarbonizing treatment on the magnetic properties of grain-oriented electrical steels with 3% Si. The study subjected grain-oriented electrical steel samples to heat treatment simultaneously to different tensile stresses. After the heat treatment, the samples were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The best results, in terms of core losses, were obtained for the sample treated without stretching. The presence and size of MnS and AlN precipitates were also found to significantly influence the magnetic properties. These results focused on the importance of controlling stretching during annealing to optimize the magnetic performance of grain-oriented electrical steels for applications in transformers and generators.

Abstract in English:

Abstract This study addresses the issue of cracking in WC/Ni60 cladded layers with high WC content. The effects of different WC contents on the formation quality, microstructure, and microhardness of WC/Ni15 cladded layers, as well as the influence of various nickel alloys (Ni15, Ni35, and Ni60) on Ni+20% WC cladded layers, were investigated. The results show that as the WC content increases, the microstructure of WC/Ni15 cladded layers becomes denser and finer, with the formation of W-rich compounds and carbides such as Ni2W4C and W2C, resulting in an increase in hardness. When the WC mass fraction reaches 50%, cracks and larger pores appear in the WC/Ni15 cladded layer, and the higher viscosity of the melt pool causes W-rich compounds to be uniformly distributed throughout the layer. At a WC mass fraction of 20%, the pores in the cross-sections of WC/Ni15, WC/Ni35, and WC/Ni60 cladded layers decrease sequentially. The microstructure transitions from cellular to dendritic, the dendrite spacing decreases, and hardness increases, with W-rich compounds mainly concentrated at the top of the cladded layer. In the Ni60+20% WC cladded layer, the increase in borides leads to the formation of cracks. The Ni15+40% WC cladded layer, however, does not exhibit cracks and has a hardness comparable to that of the Ni60+20% WC cladded layer. Under the same conditions, adding a high content of WC particles to Ni15 powder results in a crack-free cladded layer with higher hardness, making it more favorable for industrial applications of WC/Ni cladded layers.

Abstract in English:

ABSTRACT The hydrophobicity of a surface gives it peculiar properties, making it non-sticky and more resistant to corrosion. Stearic acid (SA) is saturated carboxylic acid that has C18 in molecular structure. The longer the carbon chains of fatty acids in a coating, the lower its solubility in water and consequently the greater its superhydrophobic characteristic. This study is of fundamental importance because it presents the potential for technology transfer since the methods used in this study, both for manufacturing and deposition of coatings, are simple and can be applied industrially, and also use low-cost products such as SA. In this sense, the objective of this study is to evaluate the corrosion resistance of the 5052 aluminum alloy when coated with superhydrophobic films based on stearic acid. Stearic acid (SA) in a 1% ethanolic solution was deposited using dip-coating. Aluminum substrate coated with SA was tested with three variations of surface morphology: as received (L), sanded (#) and sandblasted (J). The morphology of the substrates was analyzed by scanning electron microscopy (SEM), and the chemical composition of the coating/substrates, by energy dispersive spectroscopy (EDS). Contact angle (CA) analysis was performed to verify the hydrophobicity provided by the coating. Corrosion resistance was assessed using electrochemical impedance spectroscopy (EIS) and salt spray testing. The blasted surface yielded the best contact angles, with a mean angle of 158.9°. The superhydrophobic sample showed better corrosion resistance than the other substrates, which had contact angles below 150°.

Abstract in Portuguese:

RESUMO A crescente eletrificação global e a necessidade da redução das emissões de CO2 impulsiona o aprimoramento das baterias de chumbo-ácido, ampliando seu papel tanto na mobilidade veicular quanto na infraestrutura de armazenamento de energia. Este estudo propõe uma nova abordagem dinâmica para a caracterização eletroquímica dos produtos de corrosão em ligas de chumbo, dividindo a análise em duas fases: (i) formação da camada de corrosão e (ii) consolidação dessa camada. Foram realizadas voltametrias cíclicas e espectroscopias de impedância eletroquímica em amostras de chumbo puro (Pb) e liga Pb1,5Sn, em solução de H2SO4 5M a 25°C, com varredura de +1,3V a +2,2V. Os ensaios evidenciaram diferenças na cinética de corrosão e na estabilidade da camada de PbO2 formada. A abordagem dinâmica mostrou que conclusões podem divergir dependendo do ciclo analisado, destacando a importância de considerar a evolução temporal das reações. Os resultados indicam que a liga Pb1,5Sn apresentou maior resistência à corrosão ao longo dos ciclos, evidenciada pelo aumento da impedância eletroquímica e da estabilidade da camada de PbO2. A metodologia proposta aprimora a interpretação dos fenômenos eletroquímicos, sendo útil para otimizar a seleção de materiais em baterias de chumbo-ácido.

Abstract in English:

ABSTRACT The growing global electrification drives the improvement of lead-acid batteries, expanding their role in both vehicular mobility and energy storage infrastructure. This study proposes a new dynamic approach for the electrochemical characterization of corrosion products in lead alloys, dividing the analysis into two phases: (i) formation of the corrosion layer and (ii) consolidation of this layer. Cyclic voltammetry and electrochemical impedance spectroscopy were performed on samples of pure lead (Pb) and Pb1.5Sn alloy in 5M H2SO4 solution at 25°C, with a scan range of +1.3V to +2.2V. The tests revealed differences in the corrosion kinetics and stability of the PbO2 layer formed. The dynamic approach showed that conclusions can vary depending on the cycle analyzed, highlighting the importance of considering the temporal evolution of reactions. The results indicate that the Pb1.5Sn alloy exhibited higher corrosion resistance throughout the cycles, as evidenced by the increase in electrochemical impedance and the stability of the PbO2 layer. The proposed methodology enhances the interpretation of electrochemical phenomena, proving useful for optimizing material selection in lead-acid batteries.

Abstract in English:

ABSTRACT Fibers for e-waste management are emerging as sustainable materials, often derived from natural or recycled sources, to replace non-biodegradable components in electronic products. This study investigates the development and characterization of carbon fiber-reinforced composites derived from electronic polymer toy waste (EPTW), emphasizing sustainability and material reutilization. The primary objective is to fabricate and evaluate composite materials with varying compositions of EPTW (CF-0EPTW, CF-5EPTW, CF-10EPTW, CF-15EPTW, CF-20EPTW) to assess their mechanical, thermal, and morphological properties. The polymer matrix and carbon fibers were meticulously processed and mixed with electronic toy waste particles using precise ratios and advanced fabrication techniques. Materials were tested for tensile, compressive, flexural, and impact strengths under controlled conditions, adhering to ASTM standards. The results were analyzed using Response Surface Methodology (RSM) to optimize process parameters and identify trends. A comparative analysis between experimental outcomes and RSM predictions demonstrated excellent correlation, validating RSM as a robust tool for optimizing material properties. Morphological characterization, including Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Energy Dispersive X-ray Analysis (EDAX), provided detailed insights into the composites’ microstructural integrity and elemental composition. The results confirm that CF-0EPTW exhibits superior mechanical performance and thermal stability, while RSM efficiently predicts composite behavior, surpassing experimental variations in accuracy.

Abstract in English:

ABSTRACT This current work, studied the effects of nano silicon nitride (n-Si3N4) particles incorporated with AA8050 matrix using a stir-casting method. Physical characteristics including density and porosity were measured. The mechanical characteristics including the impact strength (IS), ultimate tensile strength (UTS), elongation (El), and Vickers hardness (HV) were evaluated according to the standards. Metallurgical characteristics including Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD) examined the synthesized composites. The theoretical density rise for 3.5% reinforcement is capped at 1.6%, while the experimental density drop is 3.1%. Also incorporating n-Si3N4 into the matrix significantly increased the UTS, HV, and IS with a percentage of 11.04%, 25.88%, 29.88% accordingly. SEM of AA8050 Composites revealed a dispersion of n-Si3N4 particles in the AA8050. When analyzing the EDS of AA8050 Composites, a high-intensity peak indicates that the composites have a high rate of Al by weight. In XRD to all appearances, the Al phase encloses the n-Si3N4 particles.

Abstract in English:

ABSTRACT The intent of the existing research was to examine the tribological characteristics of AA2024/Aluminium Nitride (AlN), synthesized through stir casting route (SCR). The composite specimens were developed at various amounts of (0, 5, 10 and 15 wt.%) AlN particles (P). The pin-on-disc (POD) wear tester was used to predict the wear of the proposed Metal Matrix Composites (MMCs). The experiments were performed by considering three variables such as load (LD), sliding velocity (SV) and sliding distance (SD). Taguchi procedure has been applied to propose the plan of experiments and tests were executed as per L16 orthogonal array (OA) layout. Signal-to-noise (S/N) ratio were used to establish the optimal site of variables in order to obtain lesser wear rate (WR) and co-efficient of friction (CF) for the tested composites. The impact of parameters on WR and CF were analyzed by analysis of variance (ANOVA). The examinations found that the ‘LD’ has more dominant factor on WR with a contribution of 75.86%, and the wt.% of P has more influence on CF with a contribution of 75.06%, respectively.

Abstract in English:

ABSTRACT Aluminium Alloy Hybrid Metal Matrix Composites (AAHMMCs) have been utilized in automotive, marine, military and aerospace applications due to their high strength-to-weight ratio, microhardness, tensile, impact, and compressive strength, along with superior tribological properties. This study focused on optimizing ultrasonic-assisted stir casting of AA7075/WC/SiC Hybrid Metal Matrix Composites (HMMCs) by varying the wt.% of WC and SiC (6, 8, and 10), melting temperature (700, 750, and 800°C), stirring time (5, 10, and 15 min), and stirring speed (200, 225, and 250 rpm), while keeping ultrasonic parameters constant. The inclusion of 0.25 and 0.5 wt.% Scandium increased microhardness by 18% due to the Hall-Petch effect and Al3Sc precipitates, which strengthened the material. Ultrasonic assistance improved grain refinement and uniform particle distribution. The optimal process parameters were determined as a 750°C melting temperature, 250 rpm stirring speed, 5 min stirring time, and 8 wt.% WC+SiC. Aging at 300°C improved microhardness (by 15%), tensile strength (by 14.3%), compressive strength (by 12.4%), and wear resistance (by 51%) due to Mg2Si and Mg2Zn precipitates. Aging at 400°C increased impact strength by 59%, attributed to Al2Cu precipitate.

Abstract in English:

ABSTRACT This study explores the impact of incorporating recycled brick sand as a partial replacement for natural sand on the mechanical and transport properties of roller-compacted concrete (RCC) for dam construction. RCC mixtures were prepared with varying brick sand replacement levels and two different water/cement (W/C) ratios with cement dosages. Workability was assessed using the Vebe apparatus, while compressive and tensile strengths were evaluated at different ages. Additionally, porosity, water permeability, capillary absorption, and thermal conductivity were measured over time. Microstructural was characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results indicate that brick sand has minimal influence on the RCC Vebe time. Compressive strength improves with brick sand incorporation, particularly in the long term, with an optimal substitution level of 25%. However, porosity and sorptivity increase at higher replacement levels, negatively affecting durability. Water permeability and thermal conductivity decrease with greater brick sand content, enhancing RCC’s resistance to fluid penetration and thermal properties. Variations in cement dosage and W/C ratio had a limited impact on the brick sand RCC performance. These findings suggest that partial replacement of natural sand with brick sand can enhance RCC properties while promoting sustainable material reuse in dam construction.