Search Results (5,279)

Despite increasing evidence that cigarette smoke is a significant source of indoor fine particulate matter (PM_2.5), quantitative emission factors (EFs) for PM_2.5 and its toxic chemical composition in mainstream (MS) and sidestream (SS) smoke are still not well defined. In this study, we employed a custom-designed chamber to separately collect MS (intermittent puff) and SS (continuous sampling) smoke from eleven cigarette models, representing six brands and two product types, under controlled conditions. PM_2.5 was collected on quartz-fiber filters and analyzed for carbon fractions (using the thermal–optical IMPROVE-A protocol), nine water-soluble inorganic ions (by ion chromatography), and twelve trace elements (via ICP-MS). SS smoke exhibited significantly higher mass fractions of total analyzed species (84.7% vs. 65.9%), carbon components (50.6% vs. 44.2%), water-soluble ions (17.1% vs. 13.7%), and elements (17.0% vs. 7.0%) compared to MS smoke. MS smoke is characterized by a high proportion of pyrolytic organic carbon fractions (OC₁–OC₃) and specific elements such as vanadium (V) and arsenic (As), while SS smoke shows elevated levels of elemental carbon (EC1), water-soluble ions (NH₄⁺, NO₃⁻), and certain elements like zinc (Zn) and cadmium (Cd). The toxicity-weighted distribution indicates that MS smoke primarily induces membrane disruption and pulmonary inflammation through semi-volatile organics and elements, whereas SS smoke enhances oxidative stress and cardiopulmonary impairment via EC-mediated reactions and secondary aerosol formation. The mean OC/EC ratio of 132.4 in SS smoke is an order of magnitude higher than values reported for biomass or fossil-fuel combustion, indicative of extensive incomplete combustion unique to cigarettes and suggesting a high potential for oxidative stress generation. Emission factors (µg/g cigarette) revealed marked differences: MS delivered higher absolute EFs for PM_2.5 (422.1), OC (8.8), EC (5.0), Na⁺ (32.6), and V (29.2), while SS emitted greater proportions of NH₄⁺, NO₃⁻, Cl⁻, and carcinogenic metals (As, Cd, Zn). These findings provide quantitative source profiles suitable for receptor-oriented indoor source-apportionment models and offer toxicological evidence to support the prioritization of comprehensive smoke-free regulations. Full article

As energy systems transition toward high shares of variable renewable generation, local energy communities (ECs) are increasingly relevant for enabling demand-side flexibility and self-sufficiency. This shift is particularly evident in the residential sector, where the deployment of photovoltaic (PV) systems is rapidly growing. While mixed-integer linear programming (MILP) remains the standard for operational optimization and demand response in such systems, its computational burden limits scalability and responsiveness under real-time or uncertain conditions. Reinforcement learning (RL), by contrast, offers a model-free, adaptive alternative. However, its application to real-world energy system operation remains limited. This study explores the application of a Deep Q-Network (DQN) to a real residential EC, which has received limited attention in prior work. The system comprises three single-family homes sharing a centralized heating system with a thermal energy storage (TES), a PV installation, and a grid connection. We compare the performance of MILP and RL controllers across economic and environmental metrics. Relative to a reference scenario without TES, MILP and RL reduce energy costs by 10.06% and 8.78%, respectively, and both approaches yield lower total energy consumption and CO${}_2$-equivalent emissions. Notably, the trained RL agent achieves a near-optimal outcome while requiring only 22% of the MILP’s computation time. These results demonstrate that DQNs can offer a computationally efficient and practically viable alternative to MILP for real-time control in residential energy systems. Full article

The environmental impact of cement production is strongly associated with the high clinker content and its corresponding CO₂ emissions. This study examines the performance of low-emission cement mortars incorporating supplementary cementitious materials (SCMs), such as ground granulated blast-furnace slag (GGBFS) and fly ash, which partially replace clinker and contribute to CO₂ reduction. Six cement types (CEM I, CEM II/B-V, CEM II/B-S, CEM III/A, CEM V/A (S-V), and CEM V/B (S-V)) were assessed in 104 mortar formulations using a polycarboxylate-based superplasticizer, under varied curing temperatures (10 °C, 20 °C, 29 °C, and 33 °C). The present study is an experimental analysis of the impact of different plasticising and superplasticising admixtures on the demand for admixtures to achieve high flowability and low air content in cement-standardised mortar for admixture testing. PN-EN 480-1. The results indicate that mortars containing CEM III/A and CEM V/B (S-V) exhibited compressive strengths comparable to or superior to CEM I at 28 days, with strength gains exceeding 60 MPa at 20 °C. Workability retention at elevated temperatures was most effective in slag-rich cements. The plasticizing efficiency of the admixture decreased at temperatures above 29 °C, especially in fly ash-rich systems. The incorporation of SCMs resulted in an estimated reduction of up to 60% in clinker, with a corresponding potential decrease in CO₂ emissions of 35–45%. These findings demonstrate the technical feasibility of using low-clinker, superplasticized mortars in varying thermal environments, supporting the advancement of sustainable cementitious systems. Full article

The rubber industry is facing increasing pressure to adopt sustainable practices due to environmental concerns associated with the use of non-renewable resources and the growing accumulation of waste tyres and agricultural byproducts. This study explores the potential of partially replacing conventional carbon black (CB) with sustainable alternatives derived from agricultural waste (wine by-products) and pyrolysed waste tyres in natural rubber/styrene-butadiene rubber (NR/SBR) composites for tyre applications. A series of NR/SBR composites were formulated with varying ratios of CB to agricultural waste and pyrolysed tyre waste, while maintaining consistent levels of other additives. The resulting composites were then subjected to a comprehensive suite of analyses, including scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurements, Fourier transform infrared spectroscopy (FTIR), bound rubber content determination, Payne effect analysis, thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), and mechanical property testing. Furthermore, a Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) analysis were conducted to evaluate the environmental and economic viability of the proposed CB replacements. The results reveal that the incorporation of agricultural waste and pyrolysed tyre waste can significantly impact the curing behaviour, mechanical properties, and thermal stability of rubber composites. Importantly, some of the formulations demonstrate comparable tensile strength, elongation at break, and hardness compared to traditional CB-filled composites. The LCA and LCC analyses further highlight the potential for substantial reductions in greenhouse gas emissions, fossil resource depletion, and overall production costs, thereby supporting the transition toward more sustainable tyre manufacturing practices. Full article

The giant squid (Dosidicus gigas) is an abundant marine species with high protein content, making it a promising resource for the food and biomaterial industries. This study aimed to investigate the effect of temperature (25–100 °C) on the structural changes in sarcoplasmic, myofibrillar, and stromal proteins isolated from squid mantle. Fourier-transform infrared spectroscopy (FT-IR) and circular dichroism (CD) were employed to monitor modifications in secondary structure, while field emission scanning electron microscopy (FE-SEM) was used to examine morphological characteristics. The FT-IR analysis revealed temperature-induced transitions in amide I, II, and A bands, indicating unfolding and aggregation processes, particularly in myofibrillar and stromal proteins. CD results confirmed a loss of α-helix content and an increase in β-sheet structures with rising temperature, especially above 60 °C, suggesting progressive denaturation. FE-SEM micrographs illustrated clear morphological differences: sarcoplasmic proteins displayed smooth, amorphous structures; myofibrillar proteins exhibited fibrous, porous networks; and stromal proteins presented dense and layered morphologies. These findings highlight the different thermal sensitivities and structural behaviors of squid muscle proteins and provide insight into their potential functional applications in thermally processed foods and bio-based materials. Full article

In the present investigation, carbon dioxide (CO₂), carbon monoxide (CO), hydrocarbons (HC), nitric oxides (NO_X), particulate matter (PM), and fuel consumption were measured in a compression ignition internal combustion engine on a road route cycle in Quito, Ecuador. We used premium diesel and a mixture of diesel and cerium oxide at a concentration of 250 ppm. This research aimed to investigate the impact of cerium oxide on fossil fuels in terms of CO₂, CO, HC, NOx, PM, and fuel consumption. Five repetitions were performed for each fuel, and the results obtained were statistically analyzed using control charts. The experimental results showed a 27.1% reduction in PM, a 24.9% increase in NOx, and a 24.2% increase in HC, along with a 1% decrease in fuel consumption compared to the premium diesel case. We observed that the reduction in PM was due to the catalytic action of CeO₂, which enhances carbon oxidation. On the other hand, the increase in NOx was related to the higher temperature in the combustion chamber resulting from the improved thermal efficiency of the engine. This study provides guidelines for controlling air pollutants originating from vehicle emissions in high-altitude (over 2000 masl) road operations using cerium oxide as an additive. Full article

The article discusses the current challenges facing the energy sector in the context of climate policy, technological transformation, and the urgent need to increase energy efficiency while reducing greenhouse gas emissions. Modern thermal energy conversion technologies are analyzed, including supercritical steam and gas–steam cycles, as well as distributed systems using renewable fuels and microturbines. Particular attention is given to innovative systems with isothermal expansion, which theoretically allow operation close to the efficiency limit defined by the Carnot cycle. The study presents calculation results for conventional systems (steam, gas with regeneration, and Organic Rankine Cycle) and proposes a novel isothermal air turbine cycle. In a combined gas–steam configuration, the proposed cycle achieved an efficiency exceeding 43% at a relatively low heat source temperature of 700 K, clearly outperforming conventional steam and ORC systems under the same thermal conditions. The use of a simple working medium (air), combined with the potential for integration with renewable energy sources, makes this concept a promising and viable alternative to traditional Rankine and Brayton cycles in thermally constrained applications. Full article

The HYPEX^® process is a novel method for conditioning spent ion exchange resins from nuclear power plants, aiming to reduce final waste volume and carbon emissions by stabilizing the resins in metakaolin-based geopolymers. This study addresses the challenge posed by the natural variability of commercial metakaolin and defines a testing strategy to ensure consistent performance of the final matrix. The reactivity of two batches of metakaolin, characterized by comparable chemical composition and BET surface area, was evaluated by monitoring temperature evolution during geopolymerization at varying water-to-solid ratios. The resulting geopolymers were tested for compressive strength, water permeability, and strontium leachability to assess correlations between precursor properties and final matrix performance. Despite similar compositions, the two batches showed marked differences in compressive strength that could be linked to early thermal behavior. These findings demonstrate that conventional precursor characterization is insufficient to guarantee reproducibility and that thermal profiling is useful to predict mechanical performance. The results suggest the implementation of thermal response monitoring as a quality control tool to ensure the reliability of geopolymer wasteforms in nuclear applications. A simplified analytical model for the thermal evolution during geopolymerization was also developed, matching qualitatively the measured evolution, to suggest scale-up rules from laboratory specimens to full-scale drums, which should be achieved while preserving the thermal evolution. Full article

Improving the thermal efficiency of internal combustion engines plays a crucial role in reducing fuel consumption and engine emissions. Studies have shown that the friction loss caused by the piston ring–cylinder liner pair accounts for approximately 30–40% of the engine’s total mechanical friction. The key to improving mechanical and thermal efficiency lies in reducing frictional losses through advanced solutions. However, as engine intensification increases, the growing thermal and mechanical loads lead to out-of-round deformation of the cylinder liner. This deformation reduces the sealing conformity of the piston rings, leading to increased blow-by and elevated particulate matter (PM) emissions. To address this, a dynamic–static deformation testing system for cylinder liners, combined with a multi-physics simulation for data validation, has been developed to achieve energy conservation and emission reduction in engines. Based on established strain gauge and eddy current displacement sensors, this study developed a dynamic deformation testing system, modified for a specific type of diesel engine, and analyzed the cylinder liner deformation under fired conditions. Test results show that under engine speeds ranging from 700 rpm to 1100 rpm, the overall radial out-of-roundness of the cylinder liner increased, with a maximum deformation of 49.2 μm. The second-order component of out-of-roundness also increases with speed, showing a maximum rise of 28.9 μm, while the third-order and fourth-order components exhibit relatively minor changes. These findings suggest that the overall radial deformation under fired conditions is mainly dominated by second-order out-of-roundness, with third-order and fourth-order components contributing marginally. Full article

The intensification of the urban thermal environment has brought attention to urban land surface temperature (ULST). Complex building geometry and manmade material lead to significant thermal radiation directionality (TRD) of the urban canopy, and the TRD effect directly influences the accuracy of ULST retrieval algorithms. Therefore, it is essential to understand and eliminate the TRD effect to achieve high-accuracy ULST. In this context, the hemispherical brightness temperature maximum–minimum discrepancy (BTD) was quantitatively analyzed via different spectral bands, component temperature thresholds, urban geometries, and component temperature differences. Meanwhile, the DART simulations database was used to systematically evaluate 1 single-kernel- and 30 dual-kernel-driven models (KDMs), which were combined from 5 base-shape kernels (RossThick, Vinnikov, uea, RossThin, and LSF) and 6 hotspot kernels (RL, Roujean, Vinnikov, LiSparseR, LiDense, and Chen). Results show that the BTD discrepancy (ΔBTD) can reach up to 0.91 K with different band emissivities, whereas the ΔBTD is over 10 K with different component temperature differences. The building density and ratio between building heights and road widths (H/W) also exhibit their importance over urban regions. In addition, the RossThick–/Vinnikov–Roujean dual-kernel KDMs demonstrate better performance with an overall RMSE of 1.12 K. The RL-series KDMs can describe the hotspot distribution well, but the uea-series KDMs outperform at the solar principal plane (SPP) and cross-solar principal plane (CSPP). Specifically, the performance of all KDMs is sensitive to the H/W and component temperature thresholds, and urban geometry can affect the TRD RMSE with increasing H/W and a depletion of high building density. The quantitative TRD analysis and comparison provide a comprehensive reference for understanding the distribution of thermal radiation, which is also a reliable basis for developing the new TRD model over urban regions. Full article

This study evaluates the impact of a Closed Crankcase Ventilation (CCV) system on Caterpillar G3516J NG engine performance and emissions, focusing on engine performance, methane (CH₄) emissions, oil consumption, and oil particle size distribution. Three configurations were analyzed: Indirect Open Crankcase Ventilation (OCV), OCV-Direct, and CCV. The results show that the CCV system significantly reduced CH₄ slip, with reductions ranging from 12% to 23% compared to the Indirect OCV configuration, and 10% to 17% compared to the OCV-Direct configuration. The CCV system also lowered oil concentration in the crankcase ventilation gas and demonstrated high filtration efficiency, achieving values between 99.22% and 99.89%. The oil particle size distribution revealed a substantial reduction in the concentration of smaller particles, with filtration efficiencies ranging from 88.77% for the smallest particles (0.032 µm–0.018 µm) to 99.89% for particles between 1 µm and 0.560 µm. These results suggest that the CCV system not only enhances engine thermal efficiency by reducing CH₄ slip but also contributes to lower oil consumption and reduced particulate matter (PM) emissions. Additionally, the study demonstrates the effects of the CCV system on engine operational parameters like crankcase pressure and performance metrics like Brake Specific Fuel Consumption (BSFC). Full article

The use of thermal insulation material in building envelopes is closely related to economic benefits, energy-savings, and carbon reduction of buildings. The construction forms of different components in building envelopes have an important influence on the optimization design of thermal insulation in building envelopes. In this study, an integrated optimization approach is proposed to search for the best solution of thermal insulation in external walls and the optimal combination scheme of different construction forms of envelope components in granaries. The integrated optimization approach consists of an orthogonal experimental design (OEDM) method-based determination module of an optimal combination scheme of different construction forms of components, an assessment model-based quantitative analysis module, and an integrated assessment indicator-based selection module of the best solution of external wall insulation. Firstly, the OEDM method is used to determine the optimal combination scheme of different construction forms of the foundation wall of an external wall, thermal insulation material, external window, roof, and floors in buildings. Secondly, integrated economic, energy, and carbon analysis models are developed to analyze comprehensive performance of external wall insulation. Finally, an integrated assessment indicator consisting of an energy balanced index, a carbon balanced index, and weight coefficients is presented to determine the best solution of external wall insulation. The applications of this optimization approach in different ecological grain storage zones in China demonstrated that the outdoor air temperature characteristics could affect the comprehensive performance of external wall insulation in granaries, significantly. The best solution of external wall insulation in granaries in Turpan city, Daqing city, Kaifeng city, Changsha city, Anshun city, and Danzhou city was expanded polystyrene insulation (EPS) with a layer thickness of 0.078 m, 0.048 m, 0.083 m, 0.089 m, 0.062 m, and 0.131 m, respectively. The greatest difference in the lowest entire construction cost and the lowest carbon emission of external wall insulation among different typical climate regions in China was 12.987 USD/m² and 6.3 kgCO2e/m², respectively. Full article

This review is focused on glass fibers and natural fibers, exploring their applications in vehicles and buildings and emphasizing their significance in promoting sustainability and enhancing performance across various industries. Glass fibers, or fiberglass, are lightweight, have high-strength (3000–4500 MPa) and a Young’s modulus range of 70–85 GPa, and are widely used in automotive, aerospace, construction, and marine applications due to their excellent mechanical properties, thermal conductivity of ~0.045 W/m·K, and resistance to fire and corrosion. On the other hand, natural fibers, derived from plants and animals, are increasingly recognized for their environmental benefits and potential in sustainable construction, offering advantages such as biodegradability, lower carbon footprints, and reduced energy consumption, with a sound absorption coefficient (SAC) range of 0.7–0.8 at frequencies above 2000 Hz and thermal conductivity range of 0.07–0.09 W/m·K. Notably, the integration of these materials in construction and automotive sectors reflects a growing trend towards sustainable practices, driven by the need to mitigate carbon emissions associated with traditional building materials and enhance fuel efficiency, as seen in hybrid composites achieving 44.9 dB acoustic insulation at 10,000 Hz and a thermal conductivity range of 0.05–0.06 W/m·K in applications such as the BMW i3 door panels. Natural fibers contribute to reducing reliance on fossil fuels, supporting a circular economy through the recycling of agricultural waste, while glass fibers are instrumental in creating lightweight composites for improved vehicle performance and structural integrity. However, both materials face distinct challenges. Glass fibers, while offering superior strength, are vulnerable to chemical degradation and can pose recycling difficulties due to the complex processes involved. On the other hand, natural fibers may experience moisture absorption, affecting their durability and mechanical properties, necessitating innovations to enhance their application in demanding environments. The ongoing research into optimizing the performance of both materials highlights their relevance in future sustainable engineering practices. In summary, this review underscores the growing importance of glass and natural fibers in addressing modern environmental challenges while also improving product performance. As industries increasingly prioritize sustainability, these materials are poised to play crucial roles in shaping the future of construction and transportation, driving innovations that align with ecological goals and consumer expectations. Full article

The development of innovative and environmentally sustainable construction materials is a strategic priority in the context of the ecological transition and circular economy. Geopolymers and alkali-activated materials, derived from industrial and construction waste rich in aluminosilicates, are gaining increasing attention as low-carbon alternatives to ordinary Portland cement (OPC), which remains one of the main contributors to anthropogenic CO₂ emissions and landfill-bound construction waste. This review provides a comprehensive analysis of geopolymer-based solutions for building and architectural applications, with a particular focus on modular multilayer panels. Key aspects, such as chemical formulation, mechanical and thermal performance, durability, technological compatibility, and architectural flexibility, are critically examined. The discussion integrates considerations of disassemblability, reusability, and end-of-life scenarios, adopting a life cycle perspective to assess the circular potential of geopolymer building systems. Advanced fabrication strategies, including 3D printing and fibre reinforcement, are evaluated for their contribution to performance enhancement and material customisation. In parallel, the use of parametric modelling and digital tools such as building information modelling (BIM) coupled with life cycle assessment (LCA) enables holistic performance monitoring and optimisation throughout the design and construction process. The review also explores the emerging application of artificial intelligence (AI) and machine learning for predictive mix design and material property forecasting, identifying key trends and limitations in current research. Representative quantitative indicators demonstrate the performance and environmental potential of geopolymer systems: compressive strengths typically range from 30 to 80 MPa, with thermal conductivity values as low as 0.08–0.18 W/m·K for insulating panels. Life cycle assessments report 40–60% reductions in CO₂ emissions compared with OPC-based systems, underscoring their contribution to climate-neutral construction. Although significant progress has been made, challenges remain in terms of long-term durability, standardisation, data availability, and regulatory acceptance. Future perspectives are outlined, emphasising the need for interdisciplinary collaboration, digital integration, and performance-based codes to support the full deployment of geopolymer technologies in sustainable building and architecture. Full article

Usually, biomass combustion in grate-fired boilers presents significant challenges due to the heterogeneous nature of the fuel, chemical composition variability, and complex thermal and chemical conversion processes along the grate. Accurate modeling of the fuel bed conversion is critical for optimizing combustion performance and reducing emissions. However, detailed bed models are often computationally intensive and time-consuming. To address this issue, the present work details a simplified empirical bed model that is integrated into a 3D computational fluid dynamics (CFD) simulation of a 35 MW industrial grate-fired boiler. The model successfully reproduced the flue gas mass flow rate, temperature, and chemical composition across different grate sections, predicting an average furnace outlet temperature of 994 °C, CO mass fraction of 779 mg/m³, CO₂ concentration of 12 vol.%, and O₂ concentration of 9.5 vol.%. These results fall within the range reported in recent CFD studies of similar systems and are consistent with operational monitoring data from the same plant. Sensitivity analyses showed that modifying the primary-to-secondary-air split ratio from 79/21 to 40/60 reduced the average CO mass fraction at the furnace outlet by more than 50%. Additionally, the average furnace temperature increased up to 1050 °C, enhancing combustion efficiency. The CFD model also demonstrated that relocating char combustion to later grate sections led to temperature imbalances near the boiler walls, emphasizing the importance of grate-specific conversion profiles. These results underscore the model’s ability to guide air distribution optimization, improve combustion performance, and reduce pollutant emissions in biomass boilers. Full article