Search Results (9,788)

The increasing demand for sustainable energy and efficient wastewater treatment has driven interest in single-chamber microbial fuel cells (SCMFCs) as integrated systems for bioelectricity generation and waste remediation. This study evaluates untreated agro-industrial byproduct olive mill wastewater (OMW) as a substrate in SCMFCs. It investigates the performance of activated biochar derived from olive pomace coated on stainless-steel mesh (ACB/SSM) as a low-cost cathode material. A synthetic media was used as a control. Electrochemical performance was assessed using voltage profiles, polarization analysis, power density, chemical oxygen demand (COD%) removal, and coulombic efficiency (CE%). The synthetic media achieved higher peak voltage (0.647 ± 0.026 V) and power density (46.05 mW m⁻²), whereas OMW showed more stable voltage output and lower internal resistance. OMW exhibited superior initial COD removal (74%) and a gradual increase in CE% up to 63% over successive cycles. In contrast, synthetic media exhibited a consistent COD% of 64%; its CE% removal improved to 61%. These results demonstrate that, despite lower peak power, OMW provides a more stable and sustainable substrate for long-term SCMFC operation. The use of waste-derived biochar cathodes further enhances system feasibility by reducing cost and supporting circular economy principles. This study highlights the potential of OMW-based SCMFCs as a practical approach for simultaneous wastewater treatment and renewable energy recovery. Full article

Elastic springback is a critical challenge in sheet metal bending that directly affects dimensional accuracy and manufacturing efficiency. This study presents a comparative experimental and machine learning-based analysis of elastic springback behavior in three widely used sheet metals like stainless steel, aluminum, and copper, which are subjected to folding bending. The influence of key process parameters, namely sheet thickness (0.5 to 1.5 mm) and bending temperature (room temperature to 200 °C), was systematically examined under cold working. A cost-effective localized heating approach using a direct flame was introduced to enhance process control and reduce elastic recovery without the complexity associated with heated dies. Experimental results revealed substantial variability in elastic springback, ranging from 0.15% to 12.41%, emphasizing the fact that they are nonlinear in nature. Statistical evaluation confirmed that sheet thickness is the dominant factor governing elastic springback, while material type and temperature exhibit secondary yet meaningful effects. To improve predictive capability, five regression models (Linear, Polynomial, Support Vector, Random Forest, and Gradient Boosting) were developed and assessed. Among them, Random Forest demonstrated superior performance with the lowest prediction errors and strongest explanatory power, achieving an R² of approximately 0.85. Cross-validation further validated its robustness and generalization capability. Feature importance and SHapley Additive exPlanations (SHAP) analyses reinforced the primary role of thickness in determining elastic recovery behavior. The findings provide practical insights for selecting materials and process conditions to minimize elastic springback while highlighting the effectiveness of ensemble learning techniques for accurate prediction. This work contributes a consistent framework for enhancing bending precision and supports data-driven decision-making in modern manufacturing environments. Full article

Grounding connectors critically influence the safety and long-term reliability of earthing systems through coupled electro-thermal, mechanical, and corrosion behaviors, yet no standardized quantitative framework exists for jointly evaluating these performance dimensions across diverse deployment scenarios. This study introduces a unified multi-criteria evaluation framework applied to six grounding connector configurations spanning four alloy families and three joining technologies. Electro-thermal response was characterized by coupled finite element simulations (0–100 A), mechanical reliability by quasi-static tensile testing (n = 10 per configuration), and corrosion durability by accelerated salt-spray exposure with image-based corroded area fraction quantification. Performance metrics were normalized and aggregated using equal-weight, Analytic Hierarchy Process, and Shannon entropy weighting schemes, with the Technique for Order of Preference by Similarity to Ideal Solution applied for multi-scenario ranking. One-way analysis of variance confirmed statistically significant effects of connector type on tensile performance (F(5, 54) = 3154.90, p < 0.001). The exothermic welded joint achieved the highest mean ultimate tensile load (61.5 ± 1.5 kN), while copper mechanical connectors exhibited the lowest steady-state temperature rise (~2 K above ambient at 100 A). Compression-crimped connectors ranked first under both equal and Analytic Hierarchy Process weighting (closeness coefficients 0.737 and 0.807, respectively), while stainless steel connectors ranked first under corrosion-critical deployment scenarios. Scenario-weighted analyses demonstrate that the optimal material–process combination shifts with environmental severity, current duty, and mechanical demand, providing a reproducible, evidence-based basis for context-dependent connector specification. Full article

A hollow steel structure with a hat cross-section was axially compressed under impact or quasistatic conditions. The hat height and hat width were 40 mm. The thickness was 0.6, 0.8, and 1.0 mm. The effect of the reinforcing member attached to the main structure on the collapse behavior was experimentally investigated. The formation of buckling lobes was observed, and the energy absorption performance was evaluated. The addition of the internal reinforcing member achieved increased compressive force, exhibiting a stepped force variation. This step became more pronounced as the wall thickness increased, and it was larger under impact conditions. When the height of the reinforcing member was 20 mm, or the hollow shape is square, a higher crush strength was achieved, with a very regular collapse pattern. To explain the increase in compressive force by using the reinforcing member, the deformation energy was calculated by considering the deformed shapes and the mechanical properties of the material. The calculated increase ratio of 3.18 was comparable with the experimental result of 3.54. The strain measurement at the hat top of the structure during the initial compression revealed that the damage, where the strain level is greater than 0.003, was successfully delayed at the reinforced section in the partially reinforced structure. Full article

This study presents the development and field testing of a Pressurized Driving-Down Air Multilevel Sampler (PDA-MLS), an integrated groundwater sampling device designed for depth-discrete sampling in boreholes affected by floating non-aqueous phase liquids (NAPLs). Conventional sampling methods—such as low-flow pumps, bailers, and packer-isolated systems—often fail under these conditions due to limited accessibility, cross-contamination, or disturbance of the water column. The proposed system addresses these limitations through a controlled pressurized-gas actuation mechanism that transfers groundwater from multiple PTFE-membrane chambers installed at discrete depths. This configuration enables low-disturbance sampling below floating contaminant layers. The use of chemically inert materials (stainless steel and PTFE) minimizes sampling artifacts and ensures compatibility with volatile organic compound (VOC) analyses. A simplified hydraulic conceptual framework describing inflow, outflow, and pressure-driven displacement was developed to support purge-duration estimation and operational parameter definition. The device was tested in a 90 m deep fractured limestone aquifer contaminated by tetrachloroethylene (PCE), where floating hydrocarbons limited the applicability of conventional sampling techniques. Field testing showed stable discharge conditions (~145–160 mL/min), repeatable sampling cycles, and successful collection of depth-discrete groundwater samples under the investigated site conditions. No evidence of sampler-related hydrocarbon entrainment was observed in the collected samples within the analytical detection limits of the adopted laboratory methods. To the authors’ knowledge, the PDA-MLS represents one of the few groundwater sampling systems specifically designed to combine low-disturbance multilevel sampling with operation in wells affected by floating NAPL. These features make it a promising tool for environmental monitoring, high-resolution characterization of fractured aquifers, and long-term assessment of contaminated sites. Full article

Listeria monocytogenes is a persistent foodborne pathogen capable of forming biofilms and surviving in food-processing environments. This study investigated the impact of high-pressure processing (HPP) at 200 and 400 MPa/5 min on biofilm viability, biomass, and expression of nine virulence-associated genes in L. monocytogenes strains (n = 6) belonging to the serogroups IIa (LM8, LM40, LM41) and IVb (LM14, LM47, LM48). The pressure levels applied were selected to represent sublethal HPP conditions (below 600 MPa) that allowed the survival of the strains and thus enabled the investigation of adaptive responses in cells that escape complete inactivation. Biofilms were cultivated on stainless-steel 304, polyethylene terephthalate, and polypropylene coupons under static conditions at 25 °C for 72 h and 168 h. Biofilm viability [log₁₀(CFU/cm²)] was assessed by plate count method and biomass quantified via the biofilm production index (BPI). The cultures were subjected to HPP treatment and their ability to form biofilms was re-evaluated. HPP significantly (p < 0.05) reduced biofilm viability and biomass on all types of surfaces tested. Gene expression analysis revealed a pressure-dependent (p < 0.05) modulation of flaA and sigB, while other virulence genes (agrA, agrC, actA, prfA, hly, inlB, and degU) were generally downregulated (gene expression ratio values below 1). Serogroup IVb strains exhibited enhanced stress responses and lower biofilm survival on polyethylene terephthalate and polypropylene surfaces. These findings demonstrate that HPP modulates both phenotypic and genotypic traits linked to L. monocytogenes persistence, emphasizing the need to optimize pressure parameters and surface materials to prevent biofilm formation in HPP-treated food systems. Full article

This paper presents a new process for forming stepped shafts by upsetting with two movable deformation zones. The developed technology enables several shaft steps to be formed at the same time, thereby increasing process efficiency and reducing material consumption. A distinctive feature of the process is that it uses two forming sleeves, each with a variable cross-section of the impression, which move in an opposite direction to that of the punches during operation. This results in a simultaneous occurrence of upsetting and extrusion, thus leading to intensified plastic deformation and stabilized metal flow. The practical applicability of the process is demonstrated on the example of a forged railway axle. An analysis is carried out by the finite element method (FEM) using specimens of hot-formed C35 steel. The obtained results reveal proper material flow and the correct filling of the tool impressions. The examination of strain and stress distributions confirms favorable forming conditions. The calculated values of the Cockcroft–Latham integral indicate favorable forming conditions and a low risk of fracture initiation during the analyzed process. The results demonstrate the potential of the proposed technology and provide a basis for future experimental verification and industrial assessment. Full article

The Charpy impact resistance of monolithic high-strength and dissimilar structured steel was studied. A gas metal arc welding process was used to fabricate the structured steel by depositing a layer of austenitic stainless steel, followed by a layer of hardfacing material over the high-strength steel plate. ANSYS LS-DYNA^TM was used to simulate pendulum–striker impacts on steel Charpy samples. A Cowper–Symonds constitutive model was employed to capture the strain rate behavior. The corresponding material constitutive model parameters were obtained from the literature for the monolithic materials; an iterative numerical optimization method was used to couple the parameters of the structured steel simulation and experimental results. Numerical simulation results showed close agreement with experimental ones. Simulation is a valuable tool for explaining the fracture mechanism in the Charpy impact test and can be used to efficiently design parts made of structured steel that will be subjected to impacts or high-speed deformations. Full article

Ultra-High Molecular Weight Polyethylene (UHMWPE), the standard base material in ski manufacturing, offers excellent gliding performance but exhibits limited mechanical and scratch resistance on hard and icy snow conditions. In this work, stainless steel is proposed as a mechanically robust alternative, and its inherently higher friction against snow is addressed through surface engineering. The snow friction behavior of 301H stainless steel surfaces decorated with fishbone-like microstructures combined with Laser-Induced Periodic Surface Structures (LIPSSs) was investigated using a custom-built snow tribometer. Several pattern designs, with different pitch distances and depths, were engraved using femtosecond laser pulse irradiation. We conducted morphological, physical, and chemical investigations through microscopy, static contact angle measurements, and X-ray Photoelectron Spectroscopy analyses. Results indicate that the gliding performance is not directly related to the modifications in surface chemistry and wetting behavior of the samples but is affected by the geometry and orientation with respect to the sliding direction of the specific micro- and nano-features. Overall, we achieved friction coefficient values comparable to those found in UHMWPE with a fast and economically sustainable single-step laser-texturing process. This approach allows the industrial up-scaling of the fishbone-texture design to real-size alpine ski prototypes. Full article

In the Arabian Gulf region, saltwater desalination is considered to be a significant process in producing clean water. This paper presents a sustainable, combined process for upgrading a Doha reverse osmosis (RO) plant in Kuwait. A pilot-scale microbial desalination cell (MDC) stack is proposed as a pre-treatment unit prior to the RO process in order to improve plant performance. A cost–benefit analysis is conducted for the combined system to emphasize the significance of the MDC–RO process. In RO, the expected energy consumption is 2.6–13 kWh per m³ of desalinated water, whereas using MDC can reduce this to about 0.52–5.3 kWh/m³. Moreover, this new technology using catalytic MDCs can help in improving electric current production and reducing the amount of rejected brine and membrane fouling in the RO process. The electric current is improved by reducing MDCs’ internal resistance using a reduced graphene oxide/polyaniline composite-coated stainless steel mesh cathode electrode. Layer-by-layer electro-deposition can be applied to achieve these coatings. An intermediate zeolite filter is proposed to mitigate RO membrane fouling. The combined system’s natural zeolite-membrane filter improves water purification. In this study, we assessed the combined MDC–RO process for upgrading the Doha plant’s performance in terms of quality, cost, and time. The suggested catalytic MDC, using efficient, low-cost materials as cathode electrodes with an equivalent daily cost of 0.01 USD/m³ and a desalination efficiency of about 40%, acts as an alternative to high-cost platinum metal electrodes. The results also indicate that the equivalent daily cost of energy consumption using the MDC process is about 0.03 USD/m³, whereas the investment cost is about 0.4 USD/m³ daily for one year of cell operation. Full article

The transition from sinusoidal to pulse width-modulated (PWM) voltage excitation introduces high-frequency ripple, generating small remagnetization cycles within the main magnetization cycle and increasing total iron losses. Soft magnetic materials are essential for constructing many electrical devices, and accurate loss data are critical for reliable design and thermal dimensioning. However, magnetic material data are typically available only under sinusoidal excitation, and there is no generally accepted method for calculating PWM-induced losses during the design phase. To address this issue, loss measurements under DC-biased magnetization were performed on laminated ring cores, and the data were collected in the form of three-dimensional (3D) loss maps defined by the variables $\Delta B$, ${\displaystyle \frac{\mathrm{d}B}{\mathrm{d}t}}$ and $B_{\mathrm{bias}}$. Based on these maps, a method referred to as 3DLMB is proposed to calculate the contribution of PWM-induced losses to total iron losses by comparing minor-loop variables obtained from AC excitation with those measured under DC bias conditions. The method is experimentally validated on three ring cores with different geometrical parameters, showing agreement between calculated and measured total AC losses within ±5% over a range of switching frequencies. The reported agreement applies to the investigated M400-50A material, ring-core geometries, and operating range, while applying it to other materials or geometries requires constructing the corresponding DC-bias 3D loss map. Full article

With the increasing depletion of high-quality iron ore resources, the efficient utilization of refractory ores has become a critical challenge in the iron and steel industry. This review systematically examines recent advances in sintering granulation technologies aimed at enhancing the processing of such ores. The study focuses on two main categories: conventional intensification methods, including moisture optimization, binder application, and mixer improvements, and novel sintering processes such as press-briquetting, pelletized sintering, split-stream granulation, composite agglomeration (CAP), and pre-granulation sintering. Key findings indicate that while conventional techniques can partially improve granulation uniformity and sintering bed permeability, they remain inadequate for handling high proportions of ultrafine ores or secondary iron-bearing materials. In contrast, innovative processes like CAP and pre-granulation sintering demonstrate superior adaptability and efficiency by integrating pelletizing and sintering mechanisms, enabling the treatment of complex ores and industrial residues. The adoption of advanced intensification-granulation sintering technologies offers a viable pathway toward sustainable ironmaking, providing the steel industry with essential tools to mitigate raw material constraints, lower production costs, and support green transformation. Future efforts should prioritize intelligent control, process integration, and the scaling of emerging techniques to maximize their industrial potential. Full article

Drilling is often used to create holes in CFRP/AISI 316L hybrid stacks to facilitate the assembly process. Due to the non-uniform properties and difficult machinability of Cr-Ni-Mo AISI 316L steel, drilling CFRP/AISI 316L stacks poses significant challenges in manufacturing processes. This paper aims to evaluate the tool–workpiece interaction and the effect of the drilling strategy on the technological aspects of drilling CFRP/AISI 316L stacks. The experimental results show that cutting parameters have a significant impact on the drilling performance of CFRP/AISI 316L stacks. The AISI 316L → CFRP drilling strategy provides lower hole surface roughness with less burr formation in the AISI 316L layer, while the CFRP → AISI 316L drilling strategy is preferred in terms of minimizing delamination damage. The high temperature generated during drilling of the AISI 316L layer directly affects the hole surface quality in the CFRP layer and the phenomena occurring in the interlayer of the stack materials. The experimental results presented in this work allowed us to formulate several recommendations regarding the selection of cutting strategy and cutting parameters when drilling CFRP/AISI 316L hybrid stacks. Full article

To address the uneven deposition of zirconium conversion coatings on multiphase 55AlZnMg under short pretreatment cycles, this study investigated the time-dependent formation behavior of ZrCC in a selected H₂ZrF₆ bath. By precisely controlling the immersion time (20–90 s) and utilizing SEM-EDS and AFM characterization techniques, this study systematically revealed the growth kinetics and film-forming mechanisms of ZrCC on complex alloy surfaces. The results indicate that the Zn-rich phase on the surface of the 55AlZnMg coating, due to its relatively positive potential, preferentially induces the deposition of the film-forming material. Subsequently, dealloying occurs in the Al-rich phase and the Mg/Zn enriched regions, forming Zn-enriched regions that promote the continuous deposition of the film-forming material, ultimately achieving complete surface coverage; the film morphology evolves from an initial needle-like structure to a network structure, eventually forming a nanosheet structure. The film-forming process of ZrCC on the 55AlZnMg substrate surface is primarily driven by selective growth, with electrochemical properties of the alloy phases, significantly enhancing adhesion between the aluminum-zinc-magnesium coating and the overcoat and providing practical guidance for improving surface uniformity and interfacial adhesion of Al-Zn-Mg-coated steel. Full article

To address the environmental issues arising from the large-scale stockpiling of steel slag and to explore its efficient utilisation in road sub-bases, this study investigated the effects of cement dosage and steel slag content on the mechanical properties of cement-stabilised steel slag mixtures. Through unconfined compressive strength tests, compressive modulus of elasticity tests and splitting tensile strength tests, the study revealed the mechanisms by which cement dosage and steel slag content influence microstructure. The results indicate that as the cement content increases, the unconfined compressive strength, compressive modulus of elasticity and splitting tensile strength all show an upward trend, although the rate of increase gradually decreases. With increasing steel slag content, the unconfined compressive strength and splitting tensile strength first increase and then decrease slightly, whilst the compressive modulus of elasticity continues to rise. When 60% steel slag was incorporated, the 28-day unconfined compressive strength and splitting tensile strength reached their peak values, representing increases of 22.17% and 72.7% respectively compared to the control group. Further examination of the microstructure revealed that increasing the cement content and steel slag content enhances structural density and reduces surface porosity; however, excessive cement content and steel slag content have an adverse effect on mechanical properties. Consequently, the synergistic effect of an appropriate amount of steel slag and cement can significantly improve the mechanical properties and microstructure of the mixture. These findings are of great significance in promoting the green utilisation of solid waste materials, such as steel slag, in road engineering. Full article