Arabian Journal for Science and Engineering最新文献

This review explores the multifaceted aspects of carbon dioxide (CO₂) injectivity for geological storage in saline aquifers and depleted oil/gas reservoirs, emphasizing the significance of injectivity and its evaluation while also exploring the challenges and potential. The primary objective of this review paper is to outline the various experimental techniques employed to assess CO₂ injectivity, such as core flooding, microfluidic techniques, micro-CT, and resistivity measurements. Moving forward, the paper explores an array of factors influencing CO₂ injectivity, encompassing phenomena like salt and halite precipitation, dry-out effects, fines migration, and the complex interactions within the CO₂/brine/rock system. The influence of injection conditions is also considered, emphasizing brine concentration, injection flow rate, temperature, and strategies to enhance injectivity. Finally, it discusses the challenges encountered in CO₂ injection and future directions.

The production of Portland cement is energy and carbon intensive. Each kilogram of cement produced generates approximately 0.5–0.9 kg of CO₂ due to burning of fuel for maintaining a high temperature in the cement rotary kiln and calcination of calcium carbonate. Furthermore, conventional cementitious systems can be susceptible to degradation under harsh environmental exposures. Consequently, there is a pressing need for alternative binders that avoid the calcination of calcium carbonate (i.e., non-carbonate binders) while delivering superior strength and durability. This review synthesizes the development of non-carbonate binder systems with particular emphasis on indigenous minerals and industrial by-products available in the Kingdom of Saudi Arabia for their potential utilization in such binders. The non-carbonate binders examined include alkali-activated binders (including geopolymers), celitement (α-C₂S) binders, belite–ye’elimite (CSA) binders, Mg-based binders, lime–calcined clay (LC3) systems, and supersulfated binders. The effects of incorporating locally available indigenous minerals and industrial by-products such as limestone powder, gypsum, clays, natural pozzolans, marble and granite dust, cement kiln dust, red mud, oil ash, silicomanganese dust, and phosphogypsum were critically reviewed. The literature indicates that leveraging these binders and indigenous resources can reduce construction costs and carbon footprint while conserving natural resources and advancing compliance with emerging energy-conservation and greenhouse gas regulations.

Carbon fiber-reinforced polymer (CFRP) composites are increasingly employed in aerospace and automotive structures, yet their anisotropy and poor thermal conductivity make conventional machining prone to severe defects such as delamination, matrix cracking, and tool wear. This review provides a comprehensive analysis of non-conventional mechanical (NCM) machining processes, particularly abrasive waterjet machining (AWJM) and rotary ultrasonic machining (RUM), focusing on their mechanisms, parameter effects, modeling approaches, and optimization strategies. Comparative evaluation shows that optimized AWJM parameters (water pressure 300–380 MPa, traverse speed ≤ 1 mm/s, standoff distance 1–2 mm) can reduce kerf taper by 25–35%, surface roughness by 30–45%, and delamination by up to 40% relative to unoptimized settings. RUM, through the integration of ultrasonic vibration, achieves 60–90% lower thrust forces, 20–40% longer tool life, and 50% lower burr formation compared with conventional drilling. Finite element, CFD–FEA coupled, and SPH-based simulations have been instrumental in elucidating the dynamic interactions of abrasives and fiber–matrix interfaces, enabling predictive control of damage evolution. Recent developments in hybrid approaches, such as synchronized abrasive jets, multi-pass cutting, and longitudinal–torsional ultrasonic modes, further enhance process stability and precision. Future research should focus on AI-driven predictive modeling and multi-objective optimization and sustainable coolant and abrasive recycling systems, thereby advancing high-quality, damage-controlled machining of CFRP composites.

This review offers a practical and systematic overview of laser-directed energy deposition (L-DED) as a technological method for repairing metal components by injecting filler material or applying coatings. It transforms worn parts into reusable ones, restoring their functionality and extending their lifespan. The integration of repair processes is crucial for meeting the target of increasing material reuse by 30% over the next five years, supporting the transition toward a circular economy. The review delves into the foundational principles and applications of additive manufacturing within the repair and restoration sectors. It outlines various L-DED configurations utilized in industry, focusing on the processes and materials involved in repair, while addressing potential anomalies related to material usage. It also explores several industrial applications, highlighting challenges encountered in case studies from the aerospace, automotive, marine, manufacturing, and oil and gas industries. L-DED’s versatility in additive manufacturing is noted, as it accommodates complex geometries and is often integrated with subtractive processes as part of hybrid manufacturing, requiring additional post-processing steps such as heat treatment and hot isostatic pressing. Building on this foundation, this review contributes three distinct advances: (i) a material-structured synthesis of L-DED repair performance that distinguishes between laboratory investigations and industrial implementations across steels, titanium, nickel, cobalt, and aluminum systems; (ii) a comparative framework connecting wire-fed and powder-fed L-DED to conventional restoration techniques including tungsten inert gas welding, plasma transferred arc welding, high-velocity oxy-fuel coating, and electron beam repair, highlighting their trade-offs in rate, resolution, and defect control; and (iii) an integrated outlook on post-processing, qualification, and sustainability, consolidating data from recent case studies to quantify energy efficiency, material utilization, and environmental benefits. Together, these insights offer a data-driven perspective on the technological readiness and sustainability of L-DED for reliable and resource-efficient component repair.

The expansion of industries and the construction of additional wastewater treatment infrastructure have led to an exponential generation of wastewater treatment sludge, posing serious long-term environmental harm. As a result, pavement engineers have explored the potential use of sludge-derived materials (SDMs) to promote a circular economy and fulfill the United Nations Sustainable Development Goals. The present work is focused on the feasibility of using various SDMs, sewage sludge ash, alum sludge, industrial sludge, and petroleum as safe constituents of asphalt pavements. A combined scientometric and systematic review, supported by a SWOT analysis, was conducted on publications from 2010 to 2025. The USA and China, followed by India, were the most prolific contributors. SDMs have been shown to enhance the stiffness, durability, and resistance to moisture damage and rutting of asphalt pavements. The use of a petroleum sludge modifier was found to lower energy demand by 20% and carbon emissions by 15–39%, indicating positive environmental and economic implications. The cost of treating petroleum sludge is approximately 144 €/ton, whereas disposal costs range from 250 to 300 €/ton. Differences in sludge composition, treatment procedures, and the absence of common standards are the main obstacles to the widespread application of these materials; more structured technical and legislative initiatives are required.

Following the 2023 Kahramanmaraş Earthquakes (M_w 7.7 and 7.6) that struck Türkiye on February 6, 2023, the Ministry of Environment, Urbanization, and Climate Change (MoEUCC) initiated a large-scale post-earthquake damage assessment campaign, targeting more than 2,3 million structures within the affected region. A comprehensive field survey was carried out in and around Gaziantep, one of the most severely affected cities. The authors assessed more than 1700 structures representing a wide range of occupancy types, including residential, educational, healthcare, religious, administrative, industrial, and lodging structures. In this paper, the methodological process of post-earthquake data collection in and around Gaziantep is presented, together with the data on the distribution of damage with respect to construction period, number of stories, and building occupancy type, to ensure a complete understanding of the extent and characteristics of structural damage. The damage assessment employed two data sources: (i) the data gathered through the authors’ newly developed, novel damage-assessment software, presented here for the first time, and (ii) the official post-earthquake damage database of the MoEUCC. A further novelty of this study is the presentation of the largest dataset to date for the investigated earthquake doublet, encompassing approximately 1700 buildings. Additionally, the relationship between damage states, peak ground accelerations, and fault distances is thoroughly investigated. The detailed earthquake-hit site investigations revealed that the examined structures displayed structural inadequacies akin to those witnessed in previous seismic events, with a notable focus on the arrangement of the structural system, the quality of construction materials and reinforcement detailing.

Silica aerogels (SA) exhibit exceptional thermal insulation, extremely low density, and ultra-high porosity, making them promising additives for developing energy-efficient cementitious composites. However, incorporating SA into cement matrices often results in reduced mechanical performance, weakened interfacial bonding, and concerns about long-term durability. This review provides a structured and critical evaluation of research published between 2000 and 2025 on SA-enhanced cement-based materials. A systematic review methodology was adopted, using the Scopus, Web of Science, and ScienceDirect databases, to evaluate synthesis routes, incorporation methods, and performance outcomes. The paper provides a comprehensive overview of advances in SA-enhanced cementitious composites, with particular emphasis on their thermal insulation efficiency, fresh-state behavior, mechanical performance, and long-term durability. Despite considerable progress, current research remains fragmented in terms of structure–property relationships, performance optimization, and standardized evaluation protocols. This work highlights a major research gap in establishing consistent methodologies for assessing durability and optimizing mechanical-thermal synergy for practical applications. The objectives of this review are to consolidate existing knowledge, identify critical challenges, and propose strategic directions for enhancing the performance, scalability, and sustainability of SA-cementitious composites. The review also discusses recent innovations, including nanosilica, recycled PET fibers, graphene oxide, carbon nanotubes, and silane surface modifications, which aim to mitigate strength loss while preserving insulation benefits. Overall, this study underscores the necessity for interdisciplinary research to develop robust, cost-effective, and durable aerogel-based cementitious materials for sustainable construction.

Autonomous exploration of confined environments remains a critical challenge across domains such as disaster response and subterranean inspection. Traditional methods such as frontier-based, sampling-based, and random walk strategies have offered viable solutions, yet face limitations in communication- and Global Positioning System (GPS)-denied environments. Recently, learning-based exploration has emerged as a promising approach to enhance the autonomy and adaptability of Micro-Aerial Vehicles (MAVs) in constrained environments. This systematic literature review investigates learning-based exploration strategies for single-MAV systems, with an emphasis on deep reinforcement learning (DRL). A comprehensive search was conducted across IEEE Xplore, ScienceDirect, and Web of Science, including preprints and early-access articles published up to June 30, 2025. The review excludes multi-robot systems, pure path planning, area coverage, obstacle avoidance, and planetary exploration, while prioritising search-and-rescue, inspection, and navigation-integrated exploration in GPS- or communication-denied confined environments. From a pool of 4,335 studies, 25 met the inclusion criteria. Our analysis reveals a strong preference for model-free DRL over model-based approaches and a growing interest in sim-to-real transfer techniques. Actor-critic methods, particularly Proximal Policy Optimisation (PPO), dominate due to their robustness and training stability. Despite progress, challenges persist in real-world deployment, reward design, and generalisation. This review synthesises trends, training paradigms, simulation environments, and reward structures used for MAV learning-based exploration, highlighting progress and persistent gaps. It lays a foundation for future work by identifying opportunities for hybrid approaches, real-world validation, and benchmark development to accelerate the safe and scalable deployment of learning-based MAV systems, specifically DRL ones in unknown environments.

The expansion of autonomous vehicle (AV) use in urban areas has motivated a range of studies aimed at addressing the diverse challenges arising in this field, particularly in recent years. This paper is a review of studies that investigate how traffic congestion has been addressed in routing problems within Autonomous Mobility-on-Demand (AMoD) systems since 2015, providing an integrated framework that organizes and synthesizes congestion-aware AMoD research. Given the limited number of studies in this field, the review includes not only research focused on autonomous systems, but also studies addressing shared ride services and those that incorporate traffic congestion in a simplified and indirect manner. In addition, works that assume static traffic conditions yet contribute to routing formulations and whose modeling approaches hold potential for further realistic development are considered. Moreover, studies that do not explicitly formulate a routing problem, but employ simulation tools for traffic modeling, are also included. Across the literature, it is observed that endogenous congestion feedback significantly alters routing, rebalancing, pricing, and welfare outcomes, while introducing calibration and computational burdens, thus highlighting that a hybrid approach would yield a valuable route for advances in this field.

The conversion of CO₂ into dimethyl ether (DME) has gained significant attention due to its potential as a clean and sustainable alternative fuel. This article provides a comprehensive overview of recent advances in the catalytic conversion of CO₂ to DME, emphasizing the two-step reaction mechanism: the hydrogenation of CO₂ to methanol followed by the dehydration of methanol to DME. The challenges inherent in this process, including thermodynamic constraints and the need for highly selective catalysts, are critically examined, with particular focus on the development of bifunctional catalysts that integrate metal and acid sites. Furthermore, this article explores emerging trends in catalyst design, such as capsule catalysts, and hybrid catalysts, which aim to enhance catalytic efficiency, selectivity, and stability. Additionally, advancements in reactor design and process optimization, including integrated reactor configurations and in situ water removal systems, are discussed in the context of improving the scalability and economic viability of CO₂-to-DME conversion. Finally, the economic and environmental implications of CO₂-to-DME systems are assessed through life cycle analysis (LCA) and techno-economic evaluations, offering insights into the feasibility of commercial-scale implementation. The article concludes by identifying key research gaps and future opportunities, underlining the transformative potential of DME in global decarbonization efforts and the transition to a sustainable, low-carbon economy.