Eng, Volume 6, Issue 5 (May 2025) – 21 articles

The construction of concrete airfield pavements aims to ensure sufficient load-bearing capacity for the safe operation of aircraft. In order to reduce the pavement thickness and the associated costs, materials with improved properties compared to conventional concrete mixtures are generally used. This measure also aims to reduce the use of cement raw materials as part of a more sustainable strategy. On this basis, various fibers can be added to conventional concrete to improve the compressive and flexural strength of the concrete. Against this background, the present study aims to quantify the effect of polypropylene and steel fibers on the thickness of airfield concrete pavements. For this reason, international experience on this topic is first summarized in order to select suitable weighted values of concrete flexural strength for further analysis. Subsequently, an airfield concrete pavement for the edge of an airport runway is designed according to the Unified Facility Criteria (UFC) of the US Department of Defense. Comparisons are made between the pavement thicknesses determined using the above method and conclusions are drawn on the effects of using steel and polypropylene fibers on the design of airfield pavements. The analysis showed that the use of steel fibers can lead to a 25% reduction in concrete layer thickness, while the use of polypropylene fibers reduces the concrete layer thickness by 8–16%. Full article

This study investigates the catalytic potential of silver nanoparticles (AgNPs) synthesized using aqueous Cymbopogon citratus (lemongrass) extract for the degradation of toxic textile dyes, offering an eco-friendly solution to industrial wastewater treatment. The green-synthesized AgNPs demonstrated remarkable degradation efficiency (>94%) for multiple dyes, such as rhodamine B, methyl red, methyl orange, methylene blue, eosin yellow, and Eriochrome black T, in the presence of sodium borohydride. Optimization studies employing a one-factor-at-a-time approach revealed the critical influence of AgNPs and reductant concentration, temperature, and pH. Kinetic analysis confirmed pseudo-first-order degradation behavior. Reactive species scavenging experiments established that hydroxyl radicals and holes played dominant roles in the degradation mechanism. Notably, the AgNPs retained catalytic activity across eight reuse cycles with negligible performance loss, demonstrating strong potential for repeated application. Comparative analysis with data from the literature highlights the superior performance of C. citratus-derived AgNPs in terms of reaction rate and efficiency. This work underscores the value of plant-extract-mediated AgNPs synthesis not only for its environmental compatibility but also for its catalytic effectiveness. The study advances the practical applicability of green nanotechnology in wastewater remediation and supports its integration into sustainable industrial practices. Full article

This article presents the development and implementation of an automated digital test bench for fault diagnosis in the caution and warning panels of the UH-60 helicopter, using practices based on NASA’s systems engineering process. The research addresses the critical need to improve efficiency and accuracy in aeronautical maintenance by automating processes traditionally relying on manual techniques. Throughout the study, advanced software engineering methodologies were implemented to develop a system that significantly reduces diagnostic times and enhances the accuracy and reliability of results by integrating digital signal processing. The article highlights the economic benefits, demonstrating a substantial reduction in repair costs, and emphasizes the system’s flexibility to adapt to other aeronautical components, establishing a solid foundation for future technological innovations in aircraft maintenance. The novelty of this paper lies in integrating real-time simulation with a closed-loop diagnostic system designed primarily for the UH-60 avionics panels. This approach has not previously been applied to this series of aircraft or aeronautical components, allowing for adaptive and automated fault detection and significant improvement in diagnostic accuracy and speed in unscheduled aeronautical maintenance environments. Full article

The high amount of sludge produced from wastewater treatment plants (WWTPs) requires final disposal, forcing plant operators to search for alternatives without exerting an excessive energy demand on the global plant balance. Future revisions of the WWTP Directive will probably set additional constraints regarding the land application of sludge. Therefore, thermal treatment may seem a logical solution based on the additional energy that can be extracted from the process. The purpose of the present manuscript is to assess the integration of anaerobic digestion of sewage sludge and subsequent gasification using SuperPro Designer V13. Mass and energy balances were carried out, and the net energy balance was estimated under different scenarios. The integration of the process showed an electricity power output of 726 kW (best scenario, equivalent to 4.84 W/inhab.) against 411 kW (2.7 W/inhab.) for the single digestion case. The thermal demand of the integrated approach can be fully covered by deviating a fraction of gaseous fuels for heat production in a burner. Transforming syngas into methane by biological conversion allows densifying the gas stream, but it reduces the total energy content. Full article

This study investigates a simulation-based approach to the inverse problem of two-dimensional steady-state heat conduction in flat plates by employing Physics-Informed Neural Networks (PINNs). The primary objective is to reconstruct the temperature field and deduce unknown boundary conditions using limited labeled data sourced from conventional numerical methods. This work specifically validates the methodology using simulated data with known original conditions, rather than addressing truly unknown boundary conditions in real-world scenarios. By leveraging PINNs, the approach integrates physical laws with data-driven learning, facilitating the efficient inversion of boundary conditions and precise reconstruction of the temperature field. Within a temperature range of 10 °C to 40 °C, the method consistently achieves an average relative error of less than 10% and maintains an absolute error within 1 °C across the computational domain. By optimizing the distribution of sample points without increasing their quantity, the average relative error is further reduced by approximately 1%, thereby enhancing inversion accuracy. Additionally, implementing an adaptive weight adjustment strategy, based on learning rate annealing, further refines the method, reducing the maximum absolute error by 0.4 °C and the average relative error by 2% when compared to traditional PINNs. This research demonstrates the capability of PINNs to provide a rapid and effective solution for inverse heat conduction problems, establishing a foundation for their potential application in addressing complex inverse heat transfer challenges. Full article

Nowadays, reverse osmosis (RO) desalination has become a highly effective and economical solution to address water scarcity worldwide. The membranes used in this type of separation are influenced by both pre-treatment operations and feed water quality, leading to fouling, a complex phenomenon responsible for reducing treatment performance and shortening membrane lifespan. In this study, an autopsy of a RO membrane from the Boujdour plant was performed, and a fouling prediction tool based on transmembrane pressure (TMP) was developed using MATLAB/Simulink (R2015a) with an artificial neural network (ANN) model. The impact of membrane fouling on treatment performance was also examined through one year of monitoring. A detailed analysis of the fouled membrane was conducted using SEM/EDS techniques to characterize the fouling on the membrane’s surface and cross-section. The results revealed significant fractures on the membrane surface, with fouling predominantly consisting of organic deposits (characterized by a high oxygen concentration of 39.69%) and inorganic fouling, including Si (7.99%), Al (2.79%), Mg (1.56%), Fe (1.27%), and smaller quantities of K (0.87%), S (0.36%), and Ca (0.12%). The ANN model for predicting transmembrane pressure was successfully developed, achieving a high R² value of 92.077% and a low mean square error (MSE) of 0.005657. This predictive model demonstrates the ability to forecast future TMP cycles based on historical data. The research provides a detailed understanding of the types of fouling affecting RO membranes and contributes to the development of preventive strategies to mitigate membrane fouling. Full article

The gradual deterioration of underground water infrastructure requires constant condition monitoring to prevent catastrophic failures, reduce leaks, and avoid costly unexpected repairs. However, given the large scale and tight budgets of water utilities, it is essential to implement strategies for optimal selection and deployment of monitoring technologies. This article introduces a unified framework and methods for optimally selecting condition monitoring technologies while locating their deployment at the most vulnerable pipe segments. The approach is underpinned by an R-E-R-A-V (Redundant, Established, Reliable, Accurate, and Viable) principle and asset management concepts. The proposed method is supported by a thorough review of assessment and monitoring technologies, as well as common sensor placement approaches. The approach selects optimal technology using a combination of technology readiness levels and SFAHP (Spherical Fuzzy Analytic Hierarchy Process). Optimal placement is achieved with a k-Nearest Neighbors (kNN) model tuned with minimal topological and physical pipeline system features. Feature engineering is performed with OPTICS (Ordering Points to Identify the Clustering Structure) by evaluating the pipe segment vulnerability to failure-prone areas. Both the optimal technology selection and placement methods are integrated through a proposed algorithm. The optimal placement of monitoring technology is demonstrated through a modified benchmark network (Net3). The results reveal an accurate model with robust performance and a harmonic mean of precision and recall of approximately 65%. The model effectively identifies pipe segments requiring monitoring to prevent failures over a period of 11 years. The benefits and areas of future exploratory research are explained to encourage improvements and additional applications. Full article

Reverse engineering (RE) is essential in recreating 3D models of existing manufactured parts. It is widely used for repairing damaged components, improving used parts, and designing new items based on older models. One of the most common methods in RE is photogrammetry, which enables 3D reconstruction by capturing multiple images. Therefore, this study aimed to explore the application of mobile photogrammetry to obtain a 3D model of a train brake pad. The process started with capturing images of objects in a quick and professional manner to ensure visualization of data. This was followed by processing 2D images using Agisoft Metashape 2.2.1 software and Artificial Intelligence (AI) algorithms to create a precise 3D model. Subsequently, assessment was performed using feasibility in terms of cost, time, and accuracy. The results show that mobile photogrammetry provided an accessible and cost-effective method, alongside maximum contact stress after reducing optimization by approximately 28.42%, with maximum error value measured by the virtual model with the reference value of 0.30 mm (on Metashape) and 0.46 mm (on AI). This suggested that reverse parameterization significantly accelerated computer-aided design (CAD) model reconstruction and reduced the part redesign development cycle. By using photogrammetry and parametric modeling, engineers could accurately analyze and optimize train brake pads, ensuring safety as well as sustainability in railway operations. Additionally, RE and parametric modeling could assist in creating durable, cost-effective alternatives, and predicting appropriate replacements. Full article

This paper examines how best to use forest wood for energy application, considering that it is a limited natural resource. Eight systems are considered, including wood stoves, steam systems (boiler, power plant, and combined heat and power (CHP)), and gasification combined systems (gas turbine and combined cycle power plant, CHP, and Fischer–Tropsch). The methodology uses energy analysis and modelling and environmental/sustainability considerations to compare the energy systems. In terms of energy conversion efficiency, steam boilers and high-efficiency wood stoves for heating applications provide the highest efficiencies (~80 to 90%) and should be considered. Steam CHP systems provide lower overall energy conversion efficiencies (~75 to 80%) but do provide some electrical energy, and thus should be considered. The use of wood for the production of electricity on its own should not be considered due to low efficiencies (~20 to 30%). Particulate emissions hinder the application of high-efficiency stoves, especially in urban areas, whereas for industrial-scale steam boilers and CHP systems, particle separators can negate this problem. Gasification/Fischer–Tropsch systems have a lower energy efficiency (~30 to 50%); however, a sustainability argument could be made for liquid fuels that have few sustainable alternatives. Full article

This research aimed to enhance biodiesel stability through catalytic transfer hydrogenation using a biomimetic bimetallic catalyst and glycerol as a hydrogen donor. The effects of catalyst species, intermediate solvent, glycerol feed, and glycerol form on biodiesel stability were investigated. In this study, the examined bimetallic catalysts were Zn-Cr-bicarbonate, Zn-Cr-formate, Zn-Cr-Ni, and Cu-Ni/SiO₂. Based on the results, the most excellent catalyst was presented by Cu-Ni/SiO₂ catalyst with DMF solvent and 10 wt% glycerol feed. This combination demonstrated a significant reduction in iodine (ΔIV = −4.9 g-I₂/100 g) and peroxide values (ΔPV = −5.2 meq-O₂/kg) accompanied by an elevation of oxidative stability (ΔOS = 4.3 h). Moreover, the reaction of catalytic transfer hydrogenation using these bimetallic catalysts followed the theoretical mechanism of the simultaneous dehydrogenation–hydrogenation process with two different metals. The promotion of bicarbonate and formate ions on the bimetallic catalyst provided hydrogen transfer assistance in the catalyst. Hence, the continuous improvement of biodiesel properties is expected to promote sustainable implementation of cleaner diesel fuel. Full article

Technological innovation toward electrification and digitalization is revolutionizing aviation, paving the way for new aeronautical paradigms and novel modes to transport goods and people in urban and regional environments. Advanced Air Mobility (AAM) leverages vertical and digital mobility, driven by safe, quiet, sustainable, and cost-effective electric vertical takeoff and landing (VTOL) aircraft. A key enabler of this transformation is the development of vertiports—dedicated infrastructure designed for VTOL operations. Vertiports are pivotal in integrating AAM into multimodal transport networks, ensuring seamless connectivity with existing urban and regional transportation systems. Their design, placement, and operational framework are central to the success of AAM, influencing urban accessibility, safety, and public acceptance. These facilities should accommodate passenger and cargo operations, incorporating charging stations, takeoff and landing areas, and optimized traffic management systems. Public and private sectors are investing in vertiports, shaping the regulatory and technological landscape for widespread adoption. As cities prepare for the future of aerial mobility, vertiports will be the cornerstone of sustainable, efficient, and scalable air transportation. Full article

This work aims to explore the magnetohydrodynamic mixed convection boundary layer flow (MHD-MCBLF) on a slanted extending cylinder using Eyring–Powell fluid in combination with Levenberg–Marquardt algorithm–artificial neural networks (LMA-ANNs). The thermal properties include thermal stratification, which has a higher temperature surface on the cylinder than on the surrounding fluid. The mathematical model incorporates essential factors involving mixed conventions, thermal layers, heat absorption/generation, geometry curvature, fluid properties, magnetic field intensity, and Prandtl number. Partial differential equations govern the process and are transformed into coupled nonlinear ordinary differential equations with proper changes of variables. Datasets are generated for two cases: a flat plate (zero curving) and a cylinder (non-zero curving). The applicability of the LMA-ANN solver is presented by solving the MHD-MCBLF problem using regression analysis, mean squared error evaluation, histograms, and gradient analysis. It presents an affordable computational tool for predicting multicomponent reactive and non-reactive thermofluid phase interactions. This study introduces an application of Levenberg–Marquardt algorithm-based artificial neural networks (LMA-ANNs) to solve complex magnetohydrodynamic mixed convection boundary layer flows of Eyring–Powell fluids over inclined stretching cylinders. This approach efficiently approximates solutions to the transformed nonlinear differential equations, demonstrating high accuracy and reduced computational effort. Such advancements are particularly beneficial in industries like polymer processing, biomedical engineering, and thermal management systems, where modeling non-Newtonian fluid behaviors is crucial. Full article

Mine development in complex geological conditions is associated with the risk of mine stability loss. Geological features such as dykes are characterized by higher strength and a tendency to undergo brittle fracture under the influence of the tectonic component of stress. In this study, numerical simulations were conducted to analyze the zone of influence of the dyke and the extent of brittle fracture zones on the hanging and footwall sides relative to the dyke. The results indicate that the dyke’s influence zone increases when the dyke is situated in a gentle slope, and the size of the brittle fracture zone depends on the hanging and footwall sides of the rocks, as well as the dip angle of the dyke to 30%. It was observed that the rate of change in the brittle fracture zone varies non-linearly with increasing stress level and then stabilizes once the stress reaches the ultimate strength of the material. Consequently, the design of mine workings requires adjustments in support methods and stability assurance techniques within the dyke’s influence zone. Full article

The integration of Digital Twin (DT), Internet of Things (IoT), and Long Range Wireless (LoRa) technology in industrial automation increases efficiency, flexibility, and real-time monitoring. This study proposes a decentralized automation architecture for SCARA robots, leveraging wireless sensor networks to improve scalability, reduce the number of infrastructure components, and optimizing data-driven decision-making. Experimental validation demonstrated a 74.9% reduction in cycle time, decreasing from 55.42 s to 13.91 s across all test scenarios. The system achieved a 98.6% packet delivery success rate, ensuring reliable communication, while latency remained between 1 and 2 s, maintaining synchronization between the real robot and its digital twin. The main contributions include the following: (i) a decentralized control framework for SCARA robots, (ii) an evaluation of LoRa-based wireless communication, and (iii) experimental validation of feasibility. The results confirm the effectiveness of the system in stable real-time data transmission and precise robotic movements, offering a cost-effective alternative to conventional structures. Despite the advantages, challenges such as data security, interoperability, and real-time synchronization require further research. This study provides insights into the practical implementation of DT, IoT, and LoRa in industrial robotics, paving the way for advancements in smart manufacturing and Industry 4.0. Full article

Sudden cardiac death (SCD) represents a critical public health challenge, emphasizing the need for predictive techniques that model complex physiological dynamics. Studies indicate that the “V-trough” pattern in sympathetic nerve activity (SNA) could act as an early indicator of potentially fatal cardiac events, which can be effectively modeled using a modified version of Chua’s chaotic system, incorporating the variables of heart rate (HR), SNA, and blood pressure (BP). This paper introduces a Chua circuit with delay, and proposes a novel control design technique based on Lurie-type control systems theory combined with mixed-sensitivity ${\mathcal{H}}_{\infty }$ ($S/KS/T$) methodology. The proposed controller enables precise regulation of HR in Chua’s circuit, both with and without delay, paving the way for the development of advanced devices capable of preventing SCD. Furthermore, the developed theory allows for the project of robust controllers for delayed Lurie systems within the single-input–single-output (SISO) framework. The presented theoretical framework, supported by numerical simulations, demonstrates the effectiveness of the conceptualization, marking a considerable advance in the understanding and early intervention of SCD through robust and nonlinear control systems. Full article

Ensuring occupational safety in underground mines is a fundamental priority due to the major risks associated with this unfriendly work environment. This involves employing a set of technical, organizational, and educational measures to reduce the hazards for workers and minimize the risks of accidents and occupational diseases due to electrical and mechanical causes. Old and precarious coal extraction methods, in conjunction with obsolete infrastructure and electrical and mechanical installations, lead to high accident risk, endangering the lives of underground workers when at work. Precarious working conditions and working materials alongside the carelessness of decision makers make underground mine-based work a major cause of accidents and professional illnesses. In this paper, the authors identify, estimate, prioritize, and evaluate the vulnerabilities within underground mines and discuss the actions and resources necessary to mitigate, stop, and/or eliminate these vulnerabilities, as well as a mitigation strategy for stopping and/or eliminating them to achieve increased occupational safety. Full article

Root crops typically develop and enlarge their storage organs in the soil, where they are naturally shielded from light exposure. This characteristic influences their physiological development and presents challenges for hydroponic cultivation, as taproot enlargement is often inhibited when submerged in water. To overcome this limitation, this study introduced a novel hydroponic system that prevents direct submersion in the nutrient solution. By isolating the taproots from both soil and nutrient solution, this system allows precise control of the root-zone light environment using LED irradiation. Carrot taproots were cultivated under blue, green, and red LED light from 42 days after sowing to assess their specific responses to different wavelengths. The results revealed distinct pigment accumulation patterns influenced by light quality. Blue light induced anthocyanin accumulation in the epidermis and outer cortex within 2 days of exposure and also stimulated chlorophyll synthesis in these outer tissues. In contrast, green and red light treatments promoted chlorophyll accumulation primarily in the stele, with red light having the most pronounced effect. These findings suggest that carrot taproots exhibit specific physiological responses to light exposure, demonstrating their ability to adjust pigment biosynthesis depending on the wavelength. By integrating controlled lighting environments into hydroponic systems, this study provides new insights into root development mechanisms and presents a novel strategy for optimizing root crop cultivation. Full article

In an era marked by sustainability challenges and digital transformation, organizations face heightened uncertainty in strategic decision-making. This paper applies a conceptual tool, a fuzzy-based decision model, in the appraisal of the attractiveness of electric vehicle acquisition and navigates the multifaceted complexities of integrating economic, environmental, and infrastructural factors. A concise overview of fuzzy principles highlights their relevance to strategic management in uncertain contexts. The study uses a practical example to demonstrate how fuzzy set-based decision models assess EV attractiveness by synthesizing costs, environmental impact, vehicle depreciation, and energy independence variables. The findings reveal the fuzzy set-based decision model’s potential to enhance decision clarity and efficiency, offering managers a simple but robust framework for navigating complex trade-offs. Implications for sustainable strategic management and suggestions for future research on advanced decision support systems are discussed. Full article

Heat exchangers play a crucial role in transferring heat between two mediums, directly impacting energy efficiency, product quality, and operational safety in industrial systems. This study presents a novel approach for fouling resistance estimation using two artificial intelligence models, the cascaded forward network (CFN) and the recurrent neural network (RN), with a minimal set of six input parameters. The proposed models utilize temperature and flow sensor data from heat exchangers to predict fouling resistance. The training process is optimized using the Levenberg–Marquardt (LM) algorithm, ensuring rapid convergence and high accuracy. Model performance is assessed based on mean squared error (MSE), regression values (R), and statistical error analysis. The results demonstrate that both models achieve high accuracy in predicting fouling resistance, with the CFN model outperforming the RN model. The CFN model achieves an MSE of 1.54 × 10⁻⁸, significantly lower than the RN model (MSE = 3.05 × 10⁻⁸), resulting in a 49.5% improvement in accuracy. Additionally, statistical analysis, including error histograms and correlation analysis, further confirms the robustness of the proposed models. Compared to traditional methods, the proposed AI-based models reduce computational complexity while maintaining superior accuracy. This study highlights the potential of AI in predictive maintenance and industrial optimization, paving the way for future enhancements in intelligent fouling estimation systems. Full article

This study investigates the use of machine learning techniques to predict the unconfined compressive strength (UCS) of both stabilized and unstabilized soils. This research focuses on analyzing key soil parameters that significantly impact the strength of earth materials, such as grain size distribution and Atterberg limits. Machine learning models, specifically Support Vector Regression (SVR) and Decision Trees (DT), were employed to predict UCS. Model performance was evaluated using key metrics, including the Pearson coefficient of correlation (r²), coefficient of determination (R²), mean absolute error, and root mean square error. The findings reveal that, for unstabilized soils, both SVR and DT models exhibit remarkable performance with r² values of 0.9948 and 0.9947, respectively, with the DT model surpassing the SVR model in estimating UCS. Validation was conducted using data from four types of locally available soils in the Najd region of Saudi Arabia, although some disparities were noted between actual and predicted results due to limitations in the training data. The analysis indicates that, for unstabilized soil, grain size distribution and moisture content during testing are primary influencers of strength, whereas, for stabilized soil, factors such as stabilizer type and content, as well as density and moisture during testing, are pivotal. This research demonstrates the potential of machine learning for developing a robust classification system to enhance earth material utilization. Full article

Brain tumors pose a significant challenge in medical research due to their associated morbidity and mortality. Magnetic Resonance Imaging (MRI) is the premier imaging technique for analyzing these tumors without invasive procedures. Recent years have witnessed remarkable progress in brain tumor detection, classification, and progression analysis using MRI data, largely fueled by advancements in deep learning (DL) models and the growing availability of comprehensive datasets. This article investigates the cutting-edge DL models applied to MRI data for brain tumor diagnosis and prognosis. The study also analyzes experimental results from the past two decades along with technical challenges encountered. The developed datasets for diagnosis and prognosis, efforts behind the regulatory framework, inconsistencies in benchmarking, and clinical translation are also highlighted. Finally, this article identifies long-term research trends and several promising avenues for future research in this critical area. Full article