Diffusion Absorption Refrigeration (DAR) systems offer a sustainable alternative to vapor compression refrigeration by utilizing thermal energy instead of mechanical work, making them well-suited for renewable energy applications and waste heat recovery. This review presents a comprehensive analysis of DAR systems, incorporating a statistical evaluation of various research aspects. It focuses on energy sources, alternative working fluids, system configurations, and their impact on the coefficient of performance (COP) and operating temperature. The evolution of DAR technology is traced from early theoretical models to recent experimental developments, supported by a bibliometric study that highlights key research trends, contributing countries, and periods of increased academic activity. The review assesses DAR performance in terms of efficiency improvements, integration of renewable energy, and the use of alternative working fluids. Bibliometric data indicate a growing research interest since 1990, with a notable peak in 2019, and significant contributions from China, India, Germany, and the United States. The study concludes by emphasizing the need for further research into advanced working fluids, the integration of thermal energy storage to enhance stability, and the development of computational models for optimized design and performance. Addressing these challenges will help advance DAR technology as a viable, sustainable cooling solution, supporting innovation and contributing to global energy sustainability.

As electric vehicles (EVs) gain traction in low- and middle-income countries, their role in grid modernization and energy resilience has become increasingly relevant. This paper explores the transformative potential of bidirectional charging, Vehicle-to-Grid (V2G) and Grid-to-Vehicle (G2V), in two emerging clean mobility landscapes: Pakistan and Sub-Saharan Africa (SSA). While both regions grapple with fragile power infrastructure and nascent EV markets, they also share promising conditions for decentralized energy solutions, including rising urbanization, policy interest, and renewable energy capacity.We present a comparative analysis of the clean mobility ecosystem, policy readiness, and energy mix dynamics in Pakistan and SSA, contextualizing the promise and pitfalls of V2G/G2V adoption. To complement the policy and systems-level insights, we simulate the grid impact of varying EV penetration scenarios (baseline, low-density, and high-density) under both unidirectional (G2V) and bidirectional (V2G) frameworks. Using realistic adoption figures and residential 7–11 kW charger profiles, we model hourly load interactions to assess how EVs can either burden or stabilize local grids. Our findings reveal that while G2V adoption under high-density scenarios introduces significant early-evening grid stress, V2G strategies during peak demand periods can offset this load, effectively transforming EVs into distributed energy assets. The results underscore the need for region-specific charging policies, infrastructure investment, and digital control systems to harness the co-benefits of clean mobility and grid flexibility. Ultimately, we argue that V2G and G2V systems, if strategically implemented, can accelerate both electrified transport and energy transition pathways in Pakistan and SSA.

Low Pressure (LP) flash column is one of the equipment at CO2 removal plant, operated since 2003 with a design pressure and temperature of 1.75 kg/cm2g and 90 °C, respectively. The LP flash column functions as a place for the CO2 gas to be absorbed by aMDEA and produces lean amine. At turn around in 2021, a crack with a length approximately 5 cm was found on the inside of the top part of the LP flash column (shell area near weld). Repairment was carried out by providing a crack stopper on the crack tip, gouging, non-destructive evaluation (NDE) and welding. However, when NDE was applied, new cracks appeared around the initial crack. Some inspection and testing were further carried out to find the root cause and appropriate repair method. The results indicate that the crack has a branching pattern and its propagation cuts through trans-granular grain. Upon further analysis, there was unusually higher chloride content on the crack surface area and hardness value was higher (202-209 HB) than standard hardness value for ASTM A240-304L (≤ 201 HB) which indicates the crack was caused by chloride stress corrosion cracking (Cl-SCC). Excessive load or stress caused cracks to propagate rapidly and uncontrolled. Based on ASME PCC-2, the Butt Weld Insert Plate was selected as the repair method due to its suitability for a wide range of defects, its ability to reduce crack propagation and its provision of a permanent repair solution. Another NDE was conducted after the repair to ensure that the repairs were properly executed, with no welding defects or new cracks in the repair area. The results confirmed that there were no defects in the shell material following the installation of the butt weld insert plate.

This article explores the application of digital twin technology to enhance the operation of wafer sawing machines in materials handling and semiconductor manufacturing. An empirical study was conducted on the packaging production line at Minghsin University of Science and Technology, aimed at addressing talent training challenges and the imbalance between supply and demand in the industry. The research focuses on designing and developing an integrated system that combines digital twin and mixed reality technologies. The development process involved multiple stages, including on-site visits, machine operation instruction, certification content creation, expert validation, small-scale testing, and iterative improvements. The study evaluates the effectiveness of the system by comparing pre- and post-experiment scores provided by industry experts, analyzing operation times of five participants, and gathering qualitative feedback. Results indicate that simulation training using digital twin and mixed reality significantly enhances participants' scores and operational proficiency. This research presents a digital twin-based training and certification model that effectively improves students' success rates in certification exams.

The present work represents polarization reconfigurable MIMO antenna which is design to work at 2.4 GHz (WLAN) and C band application. An inverted U-shaped slot and two PIN diodes per radiator are incorporated in the circular patch antenna to achieve polarization reconfigurability between Linear and Circular polarization (RHCP or LHCP). A simple rectangular strip is utilized between the radiators to achieve isolation improvement from -14 dB to -22dB in the proposed design. Computer Simulation Technology (CST) 2018 is used to design and validate the polarization reconfigurable MIMO antenna with sufficient isolation. Surface current distribution, Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) and axial ratio are calculated using simulation software and used to validate circularly polarized MIMO design’s diverse behavior. The design is fabricated in low-cost FR-4 material and measurement is done to verify the simulation results. The measurement results show close agreement with simulated results and proves that the proposed design can be a better candidate for WLAN and C band application with polarization reconfiguration properties.

This study examined the application of two additive manufacturing (AM) technologies, namely Directed Energy Deposition (DED) and Laser Powder Bed Fusion (L-PBF), within the oil and gas industry with a special focus on the African context. The research highlights the role of these advanced AM technologies in enhancing efficiency and promoting sustainable industrial practices. It further explores the benefits of DED and L-PBF, such as their ability to produce complex, custom metal components, which is crucial for the African oil and gas sector in reducing downtime and operational costs. Various case studies are presented to demonstrate the practical application and benefits of these technologies in the industry. The study also addresses the challenges of implementing DED and L-PBF in Africa from an industry perspective, including skill development and infrastructural needs, and proposes various solutions. Furthermore, the environmental and economic implications of these technologies are discussed, showcasing their potential to support sustainable practices and drive industrial growth in the region. In conclusion, this paper offers a detailed perspective on the role of DED and L-PBF in revolutionising welding practices in the oil and gas industry, providing insights into the benefits, challenges, and strategies for their effective implementation in Africa.

Welding operations are known for high safety risk which requires urgent identification and prevention before they result in huge negative impacts on the nations’ gross domestic product, organizations, workers and the environment. This research aimed at developing a human factor engineering model that support loss prevention in welding industry by assessing the impact of human factors on incident frequency and safety performance in Nigerian Oil and Gas industry. The study was carried out using coded skilled welders who had at least two years’ experience and above. Descriptive study design with structured questionnaire was used for data collection and Satistical Package for Social Sciences (SPSS) version 26 Structural equation modelling software for data analysis. The results revealed that Pearson’s correlation coefficient between human factors and safety performance were statistically significant with a p-values of -0.45, 0.72, -0.50, 0.77 and 0.32 for workplace, task, personal, organizational and design factors respectively. Pearson’s correlation coefficient between human factors and incident frequency and fatality rates were 0.64, -0.55, 0.71, -0.89, and -0.45 for workplace, task, personal, organizational and design factors respectively. The structural equation regression model showed that human factors and safety performance was statistically significant with a path coefficient of -0.733, 0.860, -0.615, 0.616 and 0.430 for personal, organizational, workplace, design and task factors respectively. The structural equation regression model showed that human factors and incident frequency was statistically significant with a path coefficient of 0.59, -0.79, 0.63, -0.60 and -0.31 for personal, organizational, workplace, design and task factors respectively.The research concluded that engineered human factors would lead to improved safety performance, structural integrity and reduction in incident frequency rate. The study recommended that national, international agencies, government, professional bodies and companies should focus on human factor engineering in delivering products with structural integrity, boost performance and reduce lost time injuries and occupational diseases.

This paper conducted extensive review of extant literature on fusion-based technique for surface modification of austenitic stainless steel AISI 304 grade (304SS) for high temperature self-lubricating application using refractory carbides. Careful systematic review of available literature indicates that among the families of refractory carbides, only silicon carbide (SiC) and titanium carbide (TiC) were successfully adsorbed on the surface of 304SS via fusion melting techniques with TiC having more documentation. Yet, this information was limited to ambient temperature properties of the TiC coatings as such high temperature properties as creep-fatigue, thermal stability, hot corrosion and oxidation were not reported. Additionally, information on the incorporation of hexagonal boron nitride (hBN) into TiC coatings to address the high temperature self-lubricating challenges associated with the alloy was not available. Further, literature is scarce on multi-layer longitudinal and transverse coatings to address the challenges inherent with single layer coating. The review established that there is a wide gap in both knowledge and practice in the deposition of self-lubricating high temperature properties in 304SS substrate material using fusion-based technique which offers a window for research exploration.

Soil stabilization is crucial for enhancing the engineering properties of soil and constructing durable infrastructure, such as highways, airports, and roadways. The study's constituents were previously employed separately, and the soil's strength improved when they were coupled with other ingredients. Experimental investigations were conducted to assess the effects of varying proportions of C&D waste, CCR, and molasses on key soil characteristics, including compaction, shear strength, and plasticity. A series of crucial tests, including Atterberg limits, compaction characteristics, differential swell index, unconfined compressive strength (UCS), California Bearing Ratio (CBR), and Scanning Electron Microscope (SEM) analysis, were conducted to evaluate the performance of the stabilized soil. Test results indicated marked improvements in the Atterberg limits, reduced swell potential, and elevated values of UCS and CBR, demonstrating the effectiveness of the proposed stabilization method. CDW, CCR, and molasses enhance Unconfined Compressive Strength (UCS) by improving strength and cohesion. The addition of these chemicals significantly improved the performance of the soil, as seen by the decreased settling, enhanced strength, and greater infrastructure durability. Molasses served as an effective natural binder, while glass fibers improved tensile strength and durability by distributing stress evenly. This approach addresses waste management issues and promotes sustainable construction practices, offering a cost-effective solution for enhancing soil performance and paving the way for resilient infrastructure development.

In recent years, particular attention has been paid to the use of renewable energy, particularly biomass, for reasons related to both climate change and waste management. Biogas is frequently used in low value-added applications such as heating and fuel in engines, while it can be reformed into hydrogen, through certain process such as the process of dry reforming, of partial oxidation, of bi-reforming, or even of tri-reforming. The literature has indicated that the tri-reforming process is better than other reforming processes. Biogas tri-reforming is a simultaneous combination of endothermic dry reforming and steam reforming with exothermic methane oxidation, carried out in a single reactor to produce syngas which is an important feedstock for chemical production and energy vectors. Second, the process of tri-reforming overcomes several weaknesses of each main reform process. This article presents a new mathematical model of tri-reforming which will further optimize this type of process. The developed mathematical model was validated with literature data. Thus, the literature data used are among others, the optimal feed ratio in the tri-reforming process, CH4/CO2/H2O/O2 = 1:0.291:0.576:0.088. For optimal temperature and pressure, the data used are 1223 K and 5 bar respectively. This mathematical model makes it possible to achieve high conversion of methane (CH4) and carbon dioxide (CO2) coupled with high selectivity in hydrogen. The conversion rate of methane (CH4) can reach 99% and that of carbon dioxide (CO2) can reach 97%. The model is adapted with a high hydrogen selectivity: 2.88.