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Two-Phase Intercritical Annealing AR400 Steel: Effects on Phase Dispersion and Impact Resistance for Mining Applications
Get PDFLow-carbon AR400 abrasion-resistant steels are utilised as wear packages prolonging the production life of ground-engaging tools on earth-moving machines in South Africa\u27s mining sector. While AR400 steel is renowned for its tribological properties and wear resistance, components frequently fail prematurely due to inadequate impact absorption, necessitating premature removal from the heavy-duty production environment. This study investigates a two-phase intercritical annealing process to enhance the ductility and impact energy absorption of AR400 steel. Phase 1 involves heat treating the specimens at 1000°C for 25 minutes, then oil quenching. Phase 2 reheats the specimens to 750°C for 20 minutes, followed by cool water quenching. The efficacy of this treatment was evaluated by comparing the mechanical properties, phase dispersions, and general grain morphology of the heat-treated specimens with those of the untreated control specimens. Microstructural analysis using optical and scanning electron microscopy revealed a transformation from the martensitic phase dispersion in the control specimens, typically associated with AR400, to a primarily bainitic microstructure in the intercritically annealed samples. This change improved the impact energy absorption and ductility of the 20 mm specimen by 200%. However, the results were inconsistent across material thickness. The 12 mm and 16 mm specimens showed a decrease in impact resistivity and approximately 40% reduction in material hardness and strength, irrespective of material thickness, compromising wear resistance. The results demonstrate that while the proposed two-phase intercritical annealing heat treatment can enhance impact properties, the concurrent reduction in hardness limits its practical application in industries requiring wear and impact resistance
Diagnosis of Multiple Open-circuit and Short-circuit Faults in Three-phase Multicellular Inverter Based on Sliding Mode Observer
Get PDFThe reliability and security of multicellular converters have become crucial tools for safeguarding electrical power conversion and ensuring the continuity of electrical drives. This concern has always been paramount in numerous industrial applications. Ensuring the reliability, continuity, and robustness of the three-phase multicellular inverter critically depends on accurately diagnosing faults in insulated gate bipolar transistor (IGBT) switches; these failures carry both technical and economic consequences for electrical system conversion. Therefore, detecting and diagnosing faults is crucial to preserving converters against these potential issues. This study aims to investigate the operational behavior of the three-phase multicellular inverter under normal and faulty conditions, more precisely focusing on open-circuit and short-circuit faults in converter switches. To achieve this objective, the paper introduces a fault diagnosis technique based on a sliding mode observer for power switches in the three-phase multicellular inverter. The research is divided into two main sections. The initial segment concentrates on the aspects of sliding mode control, aiming to attain regulated output voltages, output currents, and floating capacitor voltage. This control strategy is essential for maintaining a stable and consistent operation of the inverter. The second segment focuses on fault diagnosis, analyzing the impact of a defective three-phase multicellular inverter on the overall functionality of the electrical system. The performance of the proposed algorithm is assessed and validated through simulations in the MATLAB/Simulink environment
Direct Torque Control of Dual Three Phase Induction Motor fed by Direct Power Control Rectifier using Fuzzy Logic Speed Controller
Get PDFThis paper presents an advanced Direct Torque Control (DTC) approach for a Dual Three-Phase Induction Motor (DTPIM) powered by a Direct Power Control (DPC) rectifier. Traditional control methods, such as Proportional-Integral-Derivative (PID) controllers, often face performance issues when motor system parameters vary or exhibit non-linearity. To tackle these challenges, we propose a fuzzy logic-based speed controller for DTC, which enhances adaptability to system dynamics without necessitating a precise mathematical model. The fuzzy logic controller (FLC) is particularly effective in regulating speed under varying load conditions, improving robustness, and minimizing torque ripple. Furthermore, the DPC rectifier enhances power quality by reducing harmonic distortions, maintaining a stable DC link voltage, and improving the power factor. Simulation results obtained using MATLAB/Simulink software demonstrate that the combined DTC-DPC approach with fuzzy logic control delivers a superior dynamic response with minimal overshoot. This framework offers a promising solution for high-performance industrial applications that require precise torque control and stability under fluctuating loads while also supporting sustainable energy practices through improved power efficiency
Towards Sustainability: Tracking Carbon Footprint Trends at Ezemvelo KZN Wildlife
Get PDFCarbon footprint assessment is important to combat global warming and promote sustainability. Globally, organizations committed to biodiversity conservation are essential for maintaining ecosystems and the people who inhabit them. Nonetheless, these organizations produce a carbon footprint due to their operating operations. Hence, this study aimed to assess the specific carbon footprint of the Ezemvelo KZN Wildlife (EKZNW) to improve its understanding of its environmental implications and encourage sustainable behaviors within its particular missions. Using the greenhouse gas protocol corporate accounting and reporting standard as a guide, the study methodology examines greenhouse gas emissions from direct (Scope 1) and indirect (Scopes 2 and 3) sources related to Ezemvelo wildlife activities over five years (2014/2015--2018/2019). The results show that 34,016.62 tons of carbon dioxide equivalent (tCO2e) are emitted on average each year. The majority of these emissions are caused by Scope 2 electricity consumption, which accounts for 23,475.82 tCO2e, and Scope 1 emissions, which account for 7,826.20 tCO2e. Furthermore, there was a noticeable difference in emissions between the reserves, with the Imfolozi Game Reserve having the highest emissions. The findings of this study direct EKZNW toward ecologically conscious behaviors by acting as a catalyst for educated decision-making. The insight gained paves the way for proactive steps to lower carbon emissions, coordinating conservation efforts with more general goals of sustainability and climate resilience
Goldmine Tailings Stabilization using Quarry Dust and Coal Ash for Pavement Applications - A Review
Get PDFThe quest to improve the properties of soil and other construction materials by incorporating industrial and agricultural wastes is a growing concern for the construction industry. Many researchers have recently focused on employing waste materials as stabilizers due to their good pozzolanic interactions with soil particles. Its significance in civil engineering projects such as foundations in buildings and pavement construction cannot be overemphasized. The construction of pavements usually involves using large quantities of natural earth/aggregate materials, often mixed with conventional stabilizers (cement, lime, and bitumen). There is already a shortage of natural aggregate materials in many developing nations. However, a significant quantity of waste, such as mining tailings, is generated by mining industries yearly. In contrast, the disposal of these wastes is not only expensive but has also resulted in various ecological and environmental problems. The literature has already explored methods of stabilization and solidification of mining tailings employing conventional agents. However, the use of traditional stabilizers indicates an important source of contamination for the environment. Therefore, alternative stabilizing materials are needed. The approach to this literature review included a systematic procedure for locating, choosing, and evaluating sources. The logic for the sources’ selection prioritized contemporary, peer-reviewed studies that particularly address the geotechnical properties of industrial waste products in road construction. This study reviews the geotechnical properties of industrial waste products, such as goldmine tailings, quarry dust, and coal ash and the technical benefits of using them for pavement construction
Tailoring Heat Treatment Strategies to Enhance Corrosion Resistance and Mechanical Performance of Low-Carbon Steel in Marine Environment
Get PDFThis study examines the impact of various heat-treatment processes on the corrosion resistance and mechanical properties of low-carbon steel, specifically for maritime applications. The carbon steel samples were evaluated at 750°C and subsequently cooled using two methods: normalizing and quenching. Alterations in the microstructure, hardness, and corrosion resistance were examined using contemporary techniques such as X-ray diffractometry (XRD), optical microscopy, wear testing, and electrochemical analysis in simulated seawater. The primary findings indicate that quenching enhances the hardness (from 170 to 404 HV) and corrosion resistance of steel by producing martensite, with a corrosion rate of 8.44 × 10⁻⁵ mm/year; however, this process also increases the brittleness of the steel. The process of normalizing results in a microstructure characterized by ductility, comprising both ferrite and pearlite phases. This structure exhibited a moderate level of resistance to corrosion, with a corrosion rate of 0.001018 mm/year. Conversely, the integration of normalizing with quenching results in a well-balanced microstructure, enhancing the material\u27s toughness and corrosion resistance, with a lowest corrosion rate of 6.12 × 10⁻⁵ mm/year. Testing under saline conditions revealed that the quenched samples exhibited superior performance, highlighting the significance of cooling rates in enhancing material properties. This study demonstrates the importance of heat treatment in reducing the damage caused by saltwater corrosion of carbon steel. It also provides useful information on how to ensure that marine infrastructure is more durable and functions better
Comprehensive Evaluation of Waste-Derived Fuels As Sustainable Alternatives in Cement Production
Get PDFThe cement industry accounts for approximately 7–8% of global carbon dioxide (CO2) emissions, primarily due to the energy-intensive clinker production process and reliance on fossil fuels. The environmental impact of this industry is particularly evident in the release of greenhouse gas (GHG) emissions. Therefore, the industry is exploring ways to reduce its energy costs and reliance on traditional fuels and mitigate environmental concerns by using waste-derived materials as a fuel substitute for cement production. In response to increasing environmental pressures, the substitution of fossil fuels with alternative fuels (AF) such as refuse-derived fuel (RDF), biomass, sewage sludge (SS), and used tires has emerged as a viable decarbonization strategy. This paper aims to provide a comprehensive analysis of AFs within the cement industry by reviewing previous studies, focusing on their GHG emissions and the technical, environmental, and economic implications of AFs adoption in cement kilns. A structured literature analysis was employed to evaluate fuel types, heating values, thermal substitution rates, combustion stability, and their effects on clinker quality. Data trends indicate that thermal substitution rates exceeding 80% are achievable with RDF and tire-derived fuels under optimized conditions, while biomass and SS require pretreatment for stable combustion. Environmental assessments report up to 30% reduction in CO₂ emissions and significant decreases in SOx and NOx with proper blending. The review also highlights key gaps in regional adoption and long-term performance evaluations. It concludes by recommending targeted policy support, plant-specific feasibility assessments, and integrated LCA-MCDM frameworks to scale the sustainable use of Afs
A Survey on Blockchain-driven Music Industry: Trends, Gaps, and Future Directions
Get PDFThe music industry is a vast field that has different stakeholders, such as artists, publishers, promoters, etc., for the creation, distribution, promotion, and monetization of music. Blockchains can help the music industry maintain the legal and ethical aspects of music creation, distribution, and incentivization while also preventing frauds owing to their intrinsic security attributes. We oversee various blockchain-driven music industry systems, where we comprehend 11 functions of blockchain-driven music industry perception and inspect them comprehensively towards music industry- and blockchain-linked attributions. We lumped a precursory sample of 89 resources by selecting the reports for filtering benchmarks looked up from E-libraries by applying a descriptive and persistent narrative synthesis-driven quality analysis methodology to identify trends, gaps, strengths, and weaknesses. Founded on the overview, in the blockchain-driven music industry, blockchain can pave the path for blockchain-based musical platforms (D1), decentralized music apps (D2), author attribution, monetization, and royalty payments (D3), preventing ticketing frauds (D4), music recommendation (D5), piracy prevention (D6), digital rights management systems (D7), music supply chain automation (D8), metadata optimization and tracking (D9), disintermediation (D10), and licensing (D11). Comprehensive inspection exposes that in the blockchain-driven music industry, 28.2% draw upon digital rights management (D7), 79.4% draw upon traditional blockchain, and 12.9% draw upon PoS/PoW consensus, drawing the hypothesis that there exists a trend toward reducing third-party reliance and improving revenue transparency and rights for artists. Another hypothesis is that there are gaps such as lack of practical implementation, lack of experimental validation under quantum attacks, and lack of focus for music ticketing fraud prevention, music recommendation, music supply chain automation, and metadata optimization and tracking. At last, we announce the capabilities and adversities to the perception of the blockchain-driven music industry and then contribute propositions to impede them along with future directions to cater to the gaps identified
GFEA: Leader Election Algorithm for Choosing a GroupDecision Support System Facilitator
Get PDFGroup decision support systems (GDSSs) are computer-assisted collaborative work software that facilitates group meetings asynchronously and from different locations. Even so, collaborative work in GDSS demands coordination provided by a single controlling entity known as the GDSS facilitator. However, the problem of electing a GDSS Facilitator hasn’t been treated enough in the literature, and it is often neglected. Despite that, the large number of responsibilities assigned to the facilitator makes his role crucial to the effectiveness of the group meeting. Thus, the authors focused on finding an appropriate approach for electing the facilitator. The similarities between the problematics of electing a GDSS facilitator and a distributed system leader led the authors to consider applying a distributed election algorithm for electing a GDSS facilitator. Nonetheless, current algorithms only consider computer criteria and lack a formal weighting method. Consequently, we proposed a new distributed election algorithm called GFEA (GDSS Facilitator Election Algorithm) that is designed to choose a facilitator within a GDSS. This algorithm selects a facilitator among a set of decision-makers based on multiple election criteria weighted using an objective weighting method called MEREC. A backup leader is reserved to replace the leader if he fails, and a new tie-breaking mechanism is proposed. Moreover, the initiator failure is handled. By adopting distributed system leader election principles, GFEA provides a robust solution for a decisive GDSS challenge
Effect of Soil Salinity on Thermal Behavior of Sandy Soils Under a Sahara Climate
Get PDFSoil salinity represents a harmful environmental problem that occurs either naturally or as a consequence of ineffective management practices by humans, especially in arid regions. Assessing ground temperature profile represents an important indicator for evaluating the performance of geothermal systems, used in air conditioning of building. This paper proposes a conceptual and numerical model for predicting the hydrothermal behavior of unsaturated soils. The effect of soil salinity was investigated in this research. Two soil types (sandy and sandy loam) were studied under three salinity levels. Moreover, the arid meteorological conditions of Sahara Desert were considered in the developed model. According to the results, it appears that sandy soils exhibit optimal thermal behavior at a moderate salinity concentration of C = 0.1 M, with increased surface temperatures during warmer periods and better heat conservation in colder conditions. Conversely, sandy loam soils respond most effectively at a higher salinity concentration of C = 0.2 M, particularly excelling in heat retention during the summer months. These results emphasize the intricate interaction between soil composition and salinity in regulating temperature patterns, providing important knowledge for enhancing soil management practices that are customized to particular soil types and environmental factors, with potential implications for geothermal applications