Search Results (12,466)

In this study, an eco-friendly geopolymer concrete (GPC) was synthesized using fly ash, slag, and rice husk ash as precursors, and glass fibers were incorporated to enhance its mechanical properties. And then this study investigates the residual mechanical properties and microstructure evolution of glass fiber-reinforced geopolymer concrete (GFGPC) following elevated temperature exposure and subsequent cooling. Specimens incorporating varying glass fiber volume fractions (0–2.5%) were subjected to temperatures ranging from 25 °C to 800 °C, followed by either natural cooling or water-spraying cooling. The uniaxial compressive strength, Brazilian splitting tensile strength, and three-point flexural strength of the glass fiber-reinforced GPC were experimentally determined. Furthermore, fracture performance indicators—including the energy absorption capacity at failure, characteristic length, and double-K fracture parameters—were systematically analyzed. Results indicate that a glass fiber content of 1.5% optimally enhances the composite’s mechanical performance. Under natural cooling, splitting tensile and flexural strengths exhibit a non-monotonic trend, peaking at 200 °C. Conversely, water-spraying cooling induced thermal shock generally degrades tensile and flexural properties. However, at extreme temperatures (600 °C and 800 °C), water-spray cooling facilitates matrix densification and secondary geopolymerization, resulting in a residual compressive strength increase of 12.16% and 20.77% compared to natural cooling. Furthermore, based on composite damage theory, a binary nonlinear prediction model was developed to accurately capture the coupled effects of temperature and fiber characteristics on the residual compressive strength (R² > 0.90). Coupled with scanning electron microscopy (SEM) observations, the profound effects of elevated temperatures and thermal shock on the GPC gel matrix were elucidated, and the microscopic mechanisms underlying the failure of the fiber-bridging effect at high temperatures were thoroughly investigated. The findings of this study provide a solid theoretical foundation and scientific reference for the performance assessment and repair decision-making of GPC structures post-fire exposure. Full article

The recirculating aquaculture system (RAS) marks a significant shift in global aquaculture, transitioning to controlled, land-based production. This review highlights technological advancements that enable the treatment and reuse of over 90% of water, thereby enhancing water quality and production efficiency. These features position RAS as a cornerstone of sustainable seafood production. This review introduces the RAS Readiness Level (RRL) framework which is a novel, structured approach to assess the commercial maturity of emerging RAS technologies. Applying the RRL to six key technological domains (from digital AI systems to biological PHB recovery) reveals a pervasive pilot-scale purgatory where most innovations stagnate at RRL 4–6. It further addresses advanced processes such as membrane bioreactors, denitrification reactors, and the conversion of waste into valuable products. Furthermore, this review addresses persistent challenges, including high energy demand, economic viability, and the accumulation of pathogens. Finally, it focuses on the emergent integration of the Internet of Things (IoT) and artificial intelligence (AI), which are revolutionizing RAS management through data-driven optimization. By synthesizing current innovations, this review envisions a future of intelligent, closed-loop RAS where advanced IoT- and AI-driven technologies optimize water quality and feeding strategies to minimize ecological impact while enhancing sustainability and productivity. Full article

Hydrogen is increasingly seen as a viable energy carrier in the transition to low-carbon energy systems, mainly because of its high gravimetric energy density and the absence of carbon emissions at the point of use. In this context, producing hydrogen from biomass represents a practical and sustainable option, as it allows the use of renewable and waste resources while supporting circular economy principles. This work examines the main pathways for hydrogen production from biomass, considering both thermochemical and biochemical routes, with a focus on their energy performance and practical limitations. The analysis shows that thermochemical processes, particularly gasification, remain the most developed and scalable solutions for converting solid biomass into hydrogen-rich gas, although their performance depends strongly on feedstock properties, reactor design, and operating conditions. By comparison, biochemical processes such as dark fermentation and photofermentation are more suitable for wet biomass but are limited by lower hydrogen yields and issues related to process stability. From a thermal engineering standpoint, system performance is influenced by heat transfer constraints, the energy demand of endothermic reactions, and the efficiency of gas cleaning, while parameters such as temperature, steam-to-biomass ratio, and equivalence ratio play a key role in optimization. Advanced approaches, including catalytic and sorption-enhanced gasification, show potential for improving performance. Overall, efficient hydrogen production requires a system-level approach, as no single technology can be considered universally optimal. Full article

In recent years, strong emphasis has been put on decarbonising the transport and mining sectors in an economically viable manner. To this end, ammonia is presented as a fuel, combining a high energy density (when compared to hydrogen) and zero carbon emissions. In this work, conversion of a mining haul truck engine is simulated for its use with an ammonia/diesel dual-fuel system at up to 70% Ammonia Energy Replacement (AER). The numerical setup is partially validated against engine performance data. The simulations suggest a reduction in CO${}_2$ emissions but an increase in N${}_2$O, which increases the carbon-equivalent emissions of the engine. Nevertheless, NO${}_{\mathrm{x}}$ emissions appear to be reduced, suggesting the use of post-treatment is required to deal with the issue of N${}_2$O. Cylinder temperature control is recommended for its reduction, as temperatures are lower when burning ammonia. On the other hand, the simulations suggest that ammonia slip increases with AER if diesel injection phasing is not optimised. Performance-wise, the engine develops a higher indicated mean effective pressure (IMEP) as AER increases, with a maximum at 40% AER, while combustion is delayed progressively into the engine cycle, as CAD50 values increase from −0.6 CAD ATDC at 0% AER to 20.1 CAD ATDC at 70% AER. Opportunities for further research are discussed, including more extensive experimental work to support or reject what is suggested by the simulations. Full article

This work proposes a polarization-insensitive scalable wide-angle metasurface array for highly efficient ambient energy harvesting in the 5.8 GHz Wi-Fi band. Inspired by dipole antenna principles, we design an asymmetric planar orthogonal dipole-based metasurface featuring monolithic integration of Schottky diodes (HSMS-2860) at unit cell feed gaps. This novel direct-impedance-matching strategy eliminates conventional matching networks, reducing energy conversion losses while enabling 99% radiation-to-AC efficiency across all polarization angles at 5.8 GHz. The coplanar architecture interconnects metasurface unit cells via inductors, simultaneously establishing low-loss DC channels and suppressing RF leakage. Fabricated as a 5 × 5 array, the prototype achieves 77.9% peak RF-to-DC efficiency with polarization insensitivity at an incident power of 25 dBm. Furthermore, with incident powers of 15 dBm and 20 dBm, the proposed metasurface array attained RF-to-DC conversion efficiencies exceeding 40% and 60%, respectively. This result indicates that the array is capable of achieving high energy harvesting efficiency across a broad power range. This scalable, drill-free, and polarization-insensitive design demonstrates strong potential for harvesting ambient RF energy in real-world multipath environments. Full article

Oxygen stoichiometry critically governs the phase stability and physical properties of transition-metal oxides, yet a unified understanding of how oxygen-stoichiometry-driven phase reconstruction underlies the cooperative evolution of multiple physical properties in SrCoO_x remains lacking. Here, high-quality epitaxial brown millerite SrCoO_2.5 and perovskite SrCoO_3−δ thin films were grown by pulsed laser deposition under controlled oxygen conditions. Their structural, magnetic, electrical, optical, and photocatalytic properties were systematically compared. SrCoO_2.5 exhibits antiferromagnetic insulating behavior, infrared-dominant transmittance, and higher photocatalytic activity, whereas SrCoO_3−δ shows ferromagnetism, much lower resistivity, and strong optical opacity. First-principles calculations reveal that oxygen-stoichiometry-driven phase reconstruction strongly modifies the electronic structure, accounting for the distinct magnetic, transport, and optical responses. These results establish a direct correlation between oxygen stoichiometry, structural transformation, and multifunctional properties in SrCoO_x, highlighting oxygen-vacancy ordering as an effective route to tailoring correlated oxide functionalities. Full article

The decarbonization of existing buildings remains a major challenge, particularly in contexts characterized by high energy demand and heating systems based on fossil fuels. While electrification is widely recognized as a key pathway, its direct application is often limited by building and operating conditions. This study investigates the potential of hybrid heating systems as transitional solutions through a large-scale numerical parametric simulation analysis based on representative models of the Italian residential building stock. The analysis explores the interaction between climatic conditions, system operation, and energy performance under standardized assumptions. The results reveal that hybrid systems achieve significant reductions in non-renewable primary energy (up to 39–44%) and CO₂ emissions (approximately 50–58%), primarily through the substitution of natural gas with electricity. Conversely, total primary energy may increase (approximately 2–26%) due to the contribution of renewable energy associated with heat pump operation. Operating cost savings are observed in the 25–40% range, with slight variation depending on climatic conditions. The effectiveness is not uniform, with maximum benefits in intermediate climate zones and reduced performance under more severe conditions. Overall, hybrid systems show stable and reliable performance across heterogeneous building configurations, supporting their role as robust mid-term transition technologies toward building decarbonization. Full article

To address the insufficient impact resistance of crossover frames in UHV transmission projects, this study investigates the impact response and energy absorption of undamped frames using Q420 steel, 45 steel, 6061-T6 aluminum alloy, and EP fiberglass. An energy conversion model is established, and 1:20 scaled tests and finite element simulation are conducted over 0.5–5.0 m drop heights. The results show that Q420 steel achieves the highest energy absorption; aluminum alloy balances specific energy absorption and lightweight performance; 45 steel performs moderately; fiberglass reduces peak force but has limited energy dissipation and brittle fracture risk. The efficiency of metals rises with drop height, while that of fiberglass shows a slight decline. This work provides a theoretical basis for material selection and crossover frame optimization. Full article

Ammonia decomposition represents a promising route for CO₂-free hydrogen production; however, the development of efficient and stable catalysts remains a critical challenge. In this work, a series of Al-based mixed-oxide catalysts (AlM, where M = Ni, Co, Ce) were synthesized via co-precipitation and systematically investigated to elucidate the relationship between physicochemical properties and catalytic performance in ammonia decomposition. Comprehensive characterization by X-ray diffraction (XRD), N₂ physisorption (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and pyridine-adsorbed Fourier transform infrared spectroscopy (FTIR-Py) revealed significant variations in surface area, morphology, dispersion, and acidity as a function of the incorporated metal. Among the investigated catalysts, the AlNi system exhibited superior activity, achieving the highest ammonia conversion over the studied temperature range. This enhanced performance is attributed to its high specific surface area, homogeneous mesoporous structure, and a balanced distribution of Lewis/Brønsted acid sites, which promote effective ammonia adsorption, activation and decomposition. Kinetic analysis further confirmed the favorable reaction pathway on AlNi, as evidenced by its lower apparent activation energy and higher pre-exponential factor compared to the other materials. The results demonstrate a clear correlation between surface acidity, textural properties, and catalytic performance, highlighting the pivotal role of AlM interactions in governing ammonia decomposition. These findings provide valuable insights for the rational design of efficient catalysts for hydrogen production from ammonia. Full article

Energy efficiency and sustainability are core issues in the modern design and management of industrial machinery and plants. These concerns are reflected and reinforced by the Sustainable Development Goal 9 of the United Nations (SDG9), “Industry, innovation and infrastructure”, which enshrines efficiency and optimized energy use as key features of sustainable production systems. As the engineering of industrial machinery reorients itself towards energy sustainability, attention is naturally shifting to actuators, since these components unavoidably waste part of the considerable amount of energy they absorb to execute their functions. Hydraulic actuation systems, while uniquely suited to heavy-duty applications, are particularly affected by poor energy conversion efficiency, in part due to their intrinsic properties but also because of outdated yet still common industrial practices. Consequently, for this actuation technology, there are wide margins for improvement in terms of energy waste reduction and increased environmental sustainability. This paper, therefore, investigates new applications for a management and control method conceived by the authors to drastically and systematically reduce the energy consumption of hydraulic actuators. The method is easily retrofittable to existing plants, being based on the unconventional and non-invasive deployment of a continuous-control electrohydraulic valve (CCEV) to control the supply pressure, whose required value is estimated according to the instantaneous load demands. Through the simulation of several industrial processes characterized by process parameters of varying orders of magnitude, this paper demonstrates that this innovative use of a CCEV for supply pressure regulation is an effective and widely applicable solution for energy savings and CO₂ footprint reduction in production systems that rely on hydraulic servo axes. Full article

The growing global energy demand and the urgent need to decarbonize the energy sector are driving the search for renewable and low-impact energy sources. Within this context, the conversion of biomass into hydrogen represents a viable pathway to sustainable energy, enabling both carbon mitigation and circular use of agricultural residues. This research focuses on the simulation of an integrated system that converts viticulture residues, vine prunings and grape stalks into biogenic hydrogen through a combination of pretreatment, gasification, and upgrading stages. The analysis of four different supply scenarios shows that the integration of prunings and stalks ensures the highest hydrogen yield (6.61·10⁵ Nm³/year of H₂) and the highest energy self-sufficiency, with 25% of produced syngas used to partially cover internal energy demand. Gasification enables the process to be carbon-negative, saving 1.18 kgCO₂eq for Nm³ of H₂ produced, and economically competitive, with a break-even price of 3.81 €/kg and a return on investment of ten years. The study aligns with the decarbonization goals of the European energy transition, promoting local and circular valorization of agro-industrial waste. Full article

This study investigates the environmental and energy performance of rice straw-based energy pathways in Egypt, combining life cycle assessment (LCA) with supply chain optimization to improve system efficiency. The analysis covers thirteen governorates producing over 4.45 million tons of rice straw annually. It examines the whole supply chain from paddy farming, straw collection, and transport to electricity generation and ash disposal. Total energy consumption was 11,287 TJ, dominated by farming (5673 TJ) and transport (5490 TJ). Greenhouse gas (GHG) emissions were estimated at 12,007.5 million kg CO₂-eq, with significant contributions from farming (5158 million), combustion (3630 million), and natural gas use (3039 million). Gross electricity output was 5525 GWh, yielding a net of 4973 GWh, equivalent to 1116.5 kWh per ton of straw. Scenario analysis highlighted that the optimized multi-hub system, prioritizing Cluster 1 in the Nile Delta, which contributes over 92% of straw production and 4607 GWh of net electricity, achieved a reduction of more than 25% in transport distances and an 18% decrease in diesel consumption and related emissions. Sensitivity analysis further indicated that delivered electricity and GHG intensity are more sensitive to conversion efficiency and transmission and distribution losses than to moderate changes in transport assumptions. In addition to environmental improvements, the optimized scenario indicates potential social co-benefits, including rural employment generation, additional income opportunities for farmers, and improved air quality associated with reduced open-field burning. These outcomes are presented as indicative qualitative insights. Findings confirm rice straw as a strategic, scalable, and sustainable energy resource aligned with Egypt’s Vision 2030 and the UN Sustainable Development Goals (SDGs). Full article

The redevelopment of aging planned cities in South Korea presents a significant carbon dilemma, balancing long-term operational savings against the immediate impact of embodied emissions from new construction. This study addresses this challenge by systematically identifying and prioritizing carbon reduction measures applicable across the entire building life cycle for this specific urban context. Following a comprehensive literature and case study review that produced an initial list of 28 measures, an expert panel of 21 South Korean professionals from academia, public, and private sectors was convened to evaluate their practical applicability and importance. The analysis yielded a final, prioritized framework of 23 measures. Experts strongly endorsed measures related to improving building envelope performance and enhancing energy efficiency, highlighting their immediate impact and feasibility. Conversely, several renewable energy systems and sustainable construction methods were rated lower, primarily due to concerns over high costs, low public acceptance, and prevailing technical constraints. By moving beyond a simple inventory to a prioritized, evidence-based framework, this research provides a clear and actionable guide for policymakers to make strategic decisions for low-carbon urban transformation. Full article

Solid oxide electrolysis cells (SOECs) are regarded as a promising technology for sustainable hydrogen production because of their high energy conversion efficiency. In this study, a multiphysics numerical model combined with a random particle packing framework was used to evaluate the influence of anode microstructural parameters on the electrochemical performance of a button-type SOEC. The effects of anode porosity, particle size, and electrode thickness on current density were systematically analyzed. Increasing porosity from 0.3 to 0.5 reduced the current density because of the decreased fraction of electrochemically active material. Increasing the anode particle size from 50 to 300 nm significantly shortened the triple-phase boundary (TPB) length, leading to a decrease in current density from 6289 to 5502 A m⁻². The effect of anode thickness reflects a trade-off between electrochemical activity and gas transport, with the current density increasing from 5502 to 5940 A m⁻² as the thickness increased from 10 to 20 μm. Overall, the results highlight the coupled roles of reaction-site availability and oxygen transport in determining SOEC performance. This study provides a parametric assessment of how anode microstructure affects SOEC performance and may support the structural optimization of SOEC oxygen electrodes. Full article

Maintaining safe and consistent performance in industrial energy networks necessitates the dependable detection of asynchronous motor failures. However, in practical scenarios, diagnostic models often suffer from poor generalization and high false alarm rates when faced with incomplete datasets and limited high-quality samples. Aiming to overcome the aforementioned constraints, a PCA-KPLS integrated multi-fidelity scheme is presented in this work. The method utilizes low-fidelity data to construct a Principal Component Analysis (PCA) model for extracting basic features, and then integrates a small amount of high-fidelity target data via Kernel Partial Least Squares (KPLS) to establish a cross-domain feature mapping, enabling knowledge transfer between data of different fidelities. Validation through mathematical simulation and an engineering case study on a primary air fan demonstrates that the proposed method achieves higher prediction accuracy and lower root-mean-square error compared to models using only low-fidelity or high-fidelity data, significantly reduces false alarms, and enhances the accuracy of fault diagnosis and model generalization capability when training samples are insufficient. Full article