Search Results (65)

Monitoring cropland dynamics in arid regions is critical for balancing food security with water scarcity constraints. However, distinguishing fragmented agricultural oases from spectrally similar desert vegetation remains a persistent challenge due to spectral confusion and landscape heterogeneity. To address these challenges, this study developed the STGP-OCE feature cube on the Google Earth Engine platform (GEE) by integrating the Oasis Cooling Effect (OCE) into the commonly used STGP (Spectral, Textural, Geomorphic, and Phenological) feature space, coupled with the XGBoost ensemble model. Through ablation experiments and feature importance analysis, we quantified the feature construction mechanism for arid regions. Oasis Cooling Intensity emerged as the most influential variable (Gain score: 0.315), demonstrating that the thermal signature of continuous anthropogenic irrigation serves as a robust thermodynamic proxy to resolve the spectral ambiguity between crops and drought-tolerant desert vegetation. By hierarchically coupling this thermal indicator with textural features to suppress fragmentation noise, topographic constraints to filter non-arable terrain, and phenological trajectories, the STGP-OCE feature cube achieved an Overall Accuracy of 95.12% and a Precision of 94.95%, significantly outperforming models built on lower-dimensional cubes as well as existing global land cover products. We generated a 10 m annual cropland dataset for Xinjiang, China, revealing a substantial 32.9% expansion (19,360 km²) from 2015 to 2024, mainly occurring in vulnerable oasis–desert transition zones and coinciding with reported reclamation activities. These highlight the continuous agricultural encroachment into desert margins, while the proposed STGP-OCE cube provides a reliable methodology for high-precision cropland monitoring in arid regions. Full article

Waste is increasingly recognized as misplaced biomass, underscoring its potential for reintegration into sustainable environmental management strategies. Biomass pyrolysis has emerged as a promising value-adding process capable of enhancing material properties for diverse applications. In this study, discarded Pili (Canarium ovatum Engl.) nutshells (PS) were utilized as a pyrolysis feedstock to upgrade their fuel characteristics. Pyrolysis conditions were optimized using response surface methodology (RSM) based on a central composite design (CCD) to maximize fixed-carbon content and higher heating value (HHV). The optimized biochar achieved a maximum fixed-carbon content of 86.15% and an HHV of 32.10 MJ/kg at a pyrolysis temperature of 600 °C and a residence time of 60 min, values comparable to those of conventional coal. Under these optimized conditions, the fixed-carbon content and HHV of the precursor biomass were enhanced by up to 254.7% and 58.4%, respectively. Statistical analysis indicated that pyrolysis temperature was the most significant factor influencing both fixed-carbon content and HHV (p < 0.05). The optimized biochar exhibited low volatile matter (8.88%), low ash content (4.97%), and low atomic ratios (H:C = 0.291; O:C = 0.077), indicating a high degree of carbonization and thermal stability. Energy-dispersive X-ray (EDX) analysis identified alkali and alkaline earth metals (Ca, Mg, Na), which contributed to the ash fraction, with minor heavy metals present, predominantly Pb. Hence, these findings enhance understanding of how pyrolysis conditions affect PS–biochar properties, improving fuel quality indicators. Full article

Maize is a globally significant cereal crop, while Albic soils in Northeast China are characterized by low available phosphorus (P), poor humus (HS) quality, and constrained maize yield. The synergistic effects of P fertilization on maize yield and HS quality in these soils remain poorly understood. This three-year field experiment was conducted to determine the optimal P application rate for concurrently enhancing crop productivity and HS quality. Four P application rates were established: 0 kg P₂O₅ ha⁻¹ (no P application, P0), 40 kg P₂O₅ ha⁻¹ (low P application, LP), 80 kg P₂O₅ ha⁻¹ (moderate P application, MP), and 120 kg P₂O₅ ha⁻¹ (high P application, HP). Soil nutrients status, HS fractions, dissolved organic matter (DOM) fluorescence characteristics, and structural properties of humic acid (HA) were systematically analyzed following standard analytical procedures. Principal component analysis (PCA) and Pearson correlation analysis were integrated to facilitate comprehensive data interpretation. Results indicated that the MP treatment achieved the highest maize yield (12,257.1 kg ha⁻¹) and soil organic matter (SOM, 14.8 g kg⁻¹) content, with no further yield improvement observed under HP. The MP treatment significantly increased DOM carbon content (C_DOM, 0.350 mg L⁻¹) and its humification index (HIX, 6.80), promoting the transformation of labile DOM into stable HS. HA under MP treatment exhibited enhanced structural stability, as evidenced by a lower H/C ratio (1.72), a higher O/C ratio (0.880), and a reduced E₄/E₆ ratio, reflecting increased aromatic condensation and a greater abundance of oxygen-containing functional groups. Fourier transform infrared (FTIR) spectroscopy and differential thermal analysis (DTA) confirmed that MP improved the structural complexity and thermal stability of HA. In contrast, P0 and LP restricted nutrient availability and HS formation, whereas HP induced soil acidification (pH 5.68) and disrupted HS equilibrium. Principal component analysis (PCA) and correlation analysis revealed significant positive associations between the MP treatment and SOM, C_DOM, and maize yield. This implied that moderate P input promoted stable soil organic carbon accumulation and nutrient availability, synergistically enhancing maize productivity—consistent with the study’s core goal of optimizing P management for concurrent yield and HS quality improvement in Albic soils. Accordingly, this study concluded that moderate P application (80 kg P₂O₅ ha⁻¹) was optimal for Albic soils, synergistically enhancing both maize productivity and HS quality. These findings provided theoretical support for precise P management in sustainable agricultural systems within the Albic soil regions of Northeast China. Full article

Biochar obtained from digestate is a promising material in the context of digestate management. However, it is important to note that the properties of the resulting material are largely dependent on the parameters of the pyrolysis process, with temperature being a particularly significant factor. The objective of this study was to evaluate the impacts of the digestate pyrolysis temperature on the chemical structure, thermal stability, and thermal decomposition characteristics of biochar produced at temperatures of 400, 500, 600, and 800 °C in an inert nitrogen atmosphere. Material characterization was performed using a range of analytical techniques, including elemental analysis, FTIR spectroscopy, thermogravimetric analysis (TGA/DTG), and coupled TGA–FTIR analysis, in order to identify volatile products released during the heating process. The results demonstrated that elevating the pyrolysis temperature results in progressive carbonization and aromatization of the carbon structure. Concurrently, functional groups containing oxygen and hydrogen were eliminated, as evidenced by declines in the H/C and O/C atomic ratios. FTIR analysis confirmed the disappearance of aliphatic and hydroxyl bands, as well as the dominance of aromatic structures and mineral components in biochar subjected to high-temperature treatment. The TGA results demonstrated an enhancement in thermal stability with increasing pyrolysis temperature. Concurrently, the TGA–FTIR analysis revealed a substantial decline in the emission of volatile decomposition products from biochar obtained at temperatures ≥600 °C. Overall, the pyrolysis temperature of digestate determines the utilization potential of the resulting biochar; in particular, low-temperature biochar can be used as a soil amendment and methane fermentation stimulant, while high-temperature biochar can be used for contaminant immobilization in soil and long-term carbon sequestration. Full article

The sustainable management and valorisation of agricultural and agro-industrial residues are essential to reduce environmental impacts, enhance resource efficiency, and support circular economy strategies. In Mediterranean regions, large quantities of residual biomass are annually produced from olive and citrus supply chains, representing promising feedstocks for biochar production. In this study, biochar was obtained at 600 °C in a fixed-bed reactor under a N₂ atmosphere from four representative feedstocks: olive pruning (OPr), citrus pruning (CPr), olive pomace (OPo), and citrus peel (CPe). The resulting biochar was characterized in terms of physico-chemical, energetic, and structural properties, including proximate and ultimate analyses, fuel properties, cation exchange capacity (CEC), pH, elemental ratios (O/C, H/C, N/C), thermal stability, bulk density, metal content, and surface morphology (SEM), in order to assess parameters relevant to environmental potential applications. The results highlighted clear feedstock-dependent differences. OPoB and CPeB exhibited the highest thermal stability (0.56–0.66), indicating a strong potential for long-term carbon sequestration. CPeB showed the highest CEC (47.2 cmol kg⁻¹). From an application-oriented perspective, this high CEC suggests that, when applied to soil at typical amendment rates (2–5 wt%), CPeB could potentially increase soil CEC by approximately 10–30%, thereby improving nutrient retention and cation availability. Energy yields were highest for citrus-derived biochar (42.0–47.5%), while OPoB exhibited the lowest solid yield due to its higher volatile content. SEM analysis revealed marked structural differences, with OPrB retaining an ordered lignocellulosic porous structure, whereas OPoB and CPeB displayed highly irregular morphologies, favorable for surface reactivity. Overall, this study demonstrates that olive and citrus residues are suitable feedstocks for producing biochar with differentiated properties, and that a rapid screening methodology can support feedstock selection and biochar design for targeted energy, soil amendment, and carbon management applications. Full article

Lignin is the most structurally complex component of lignocellulosic biomass. Each year, thousands of tons of lignin-rich residues from enzymatic hydrolysis are generated in sugarcane-based cellulosic ethanol biorefineries. The current study specifically utilizes lignin extracted from sugarcane bagasse as the primary feedstock for biochar production, rather than employing the raw bagasse itself. This study investigates, through pyrolytic thermal treatment of two lignin sources, the production of biochars and the evaluation of their potential applications. Kraft commercial lignin and sugarcane bagasse lignin samples, along with their corresponding biochars, were characterized by elemental and proximate analyses, higher heating value determination, spectroscopic techniques, thermogravimetric analysis, X-Ray diffraction, scanning electron microscopy coupled with energy-dispersive spectroscopy, and true density measurements. The results revealed a lower contamination level associated with the extraction process and confirmed the amorphous nature of sugarcane bagasse lignin and its derived biochar. An O/C ratio of approximately 0.3 was obtained for the sugarcane bagasse lignin biochar based on both elemental and Raman spectroscopy analyses. Both elemental composition assessment and Raman spectroscopic analysis indicated that all biochar specimens exhibited hydrogen-to-carbon (H/C) ratios exceeding 0.5. The analyses, therefore, indicated that the biochar derived from sugarcane lignin exhibited higher energy density, moderate stability and a high carbon content. The proposed approach thus provides promising alternatives for the valorizing lignin residues derived from second-generation ethanol production processes. Full article

Personal comfort systems (PCSs), which provide targeted heating or cooling to specific body parts, have emerged as a promising solution to enhance occupant comfort while reducing energy use in buildings. Among the many factors influencing PCS performance, heat transfer mechanisms (HTMs) play a pivotal role. However, a critical gap remains in the literature regarding the identification of optimal HTMs for achieving both thermal comfort and energy efficiency in PCSs. To address this gap, our study investigates the impact of conduction, convection, and radiation in PCSs on thermal comfort enhancement and energy performance under both heating and cooling modes. A meta-analysis was conducted, extracting data from 64 previous studies to evaluate the effects of HTMs of PCSs on thermal sensation vote (TSV), overall comfort (OC) and corrective energy power (CEP). Results indicate that PCSs typically improve users’ thermal sensation and comfort by about one scale unit in both heating and cooling modes. Radiative HTM is the most effective individual method, while combined conductive and convective HTMs perform best overall. Most PCSs operate efficiently, consuming less than 200 W/°C, with conduction in heating and convection in cooling being recommended for optimal comfort and energy efficiency. These findings suggest that selecting optimal HTMs for PCSs is crucial for achieving maximum comfort performance and energy savings. Data on combined HTMs of PCSs remain limited, underscoring the need for further research in this area. Future research should prioritize optimizing HTMs, especially radiative and combined methods, to maximize comfort and energy savings in PCS design. Full article

In this study, Stevia rebaudiana biomass was hydrothermally carbonized (HTC) at 215 °C for 60 min with acrylic acid (AA) as a catalyst at concentrations of 0.25, 0.50, and 1.00 mol L⁻¹. The maximum hydrochar yield (48.5%) was obtained at 0.25 mol L⁻¹ AA, while fixed carbon contents ranged from 20.79% to 34.27%. Higher heating values (HHV) varied between 26.95 and 36.61 MJ kg⁻¹, with the highest catalytic HHV (32.20 MJ kg⁻¹) achieved at 1.00 mol L⁻¹ AA (HC15). Acrylic acid addition significantly promoted deoxygenation, reducing the O/C ratio from 0.67 in raw biomass to 0.21, thereby improving fuel quality. FT-IR and XRD analyses indicated enhanced aromatization and partial graphitization with increasing acid concentration, while SEM images revealed carbon microspheres and porous morphologies. Thermogravimetric analysis showed that HC15 exhibited the lowest mass loss and highest residual carbon, indicating superior thermal stability. GC-MS analysis demonstrated that acrylic acid markedly increased phenolic derivatives, with phenol content rising from 19.47% (without catalyst) to 40.92% (1.00 mol L⁻¹ AA). The aqueous phase contained TOC values of 14,280–28,728 mg/L and COD values of 43,227–113,920 mg/L. Overall, acrylic acid-assisted HTC enhances both the energy-related properties of hydrochars and the chemical diversity of liquid products, providing a sustainable route for valorizing Stevia rebaudiana waste into value-added fuels and chemicals. Full article

This study presents a comprehensive characterization of oak biochar produced via downdraft gasification at 850 °C. The research employs a wide range of advanced analytical techniques to examine the biochar’s physical, chemical, and structural properties. Scanning electron microscopy (SEM) revealed a mesoporous structure, while Brunauer–Emmett–Teller (BET) analysis showed a surface area of 88.97 m²/g. Thermogravimetric analysis (TGA) demonstrated high thermal stability and carbon content (78.7%). X-ray photoelectron spectroscopy (XPS) and ultimate analysis confirmed the high degree of carbonization, with low O/C (0.178) and H/C (0.368) ratios indicating high aromaticity. Fourier transform infrared spectroscopy (FTIR) identified functional groups suggesting potential for CO₂ adsorption. The biochar exhibited a negative zeta potential (−31.5 mV), indicating colloidal stability and potential for soil amendment applications. X-ray diffraction (XRD) and Raman spectroscopy provided insights into the biochar’s crystalline structure and graphitization degree. These findings highlight the oak biochar’s suitability for diverse applications, including soil improvement, carbon sequestration, and environmental remediation. By filling knowledge gaps in oak-specific biochar research, this study underscores the benefits of optimized downdraft gasification and sets a foundation for future advancements in sustainable biochar applications. Full article

Stratospheric ozone shields life on Earth from harmful ultraviolet radiation and plays a crucial role in climate formation, while tropospheric ozone is a pollutant and greenhouse gas. Satellite methods based on measurements of outgoing thermal radiation are the only methods that provide information on global ozone distribution, independent of solar illumination. Since about 90% of atmospheric ozone is concentrated in the stratosphere, ozone total column measurements can be used as stratospheric ozone measurements. We present techniques for deriving information on total ozone columns (TOCs) and tropospheric ozone columns (TrOCs) from spectra of outgoing thermal radiation measured by the IKFS-2 instrument aboard the Meteor-M No. 2 satellite. The techniques are based on principal component analysis and the artificial neural network approach, providing high accuracy in TOC (less than 3%) and TrOC (within 2–4 DU) retrieval in accordance with the WMO requirements for the quality of satellite measurements. Full article

As part of the transition to low-carbon energy and for the sustainable utilisation of resources, it is necessary to seek a replacement for solid fossil fuels, but unfortunately, it is impossible to completely abandon them for various reasons at the moment, so only partial replacement with new, high-calorific, biomass-based fuels is possible. The purpose of this work is to determine the typical parameters of the co-combustion of carbonisate, coal and their mixtures, taking into account the synergetic effects influencing the combustion intensity of the mixture. Carbonisate was obtained in the process of the gasification of pinewood through the counter-blowing method at a temperature of 800–900 °C, while air was used as an oxidant. Basically, this method of gasification is used for coal in order to obtain high-calorific coke for the metallurgical industry. Also, in this study, for the first time, carbonisate was obtained from 50% pinewood and 50% lignite. The O/C and H/C ratios were determined for carbonisate. A technical and elemental analysis of the investigated fuels was carried out. A thermal analysis in oxidising medium was applied to determining the typical combustion parameters in the process of slow heating of the fuels under study. According to the results of this thermal analysis, typical heating parameters such as the ignition temperature, burnout temperature, maximum mass loss rate, combustion index, etc., were determined. It was noted that the calorific value of carbonised wood is two times higher than that of coal. The combustion index of carbonisates is 2.5–36% lower compared to that of coal. According to the results of the analysis of the interaction of the components among themselves (in the process of their joint combustion), the presence of synergetic interactions between the components was determined, which affected the change in the combustion intensity and heat release intensity. The results of this study may be useful for retrofitting coal-fired boilers to run on a mixture containing carbonisate and lignite. If carbonisate is produced from biomass, the resulting gas could be used as an energy fuel by burning it in a coal-fired boiler. Full article

This paper addresses the optimal conductor selection (OCS) problem in radial distribution networks, aiming to minimize the total costs associated with conductor investment and energy losses while ensuring voltage regulation and power balance as well as observing thermal limits. The problem is formulated as a mixed-integer nonlinear programming (MINLP) model and solved using a hybrid branch-and-bound (B&B), interior-point optimizer (IPO) approach within the Julia-based JuMP framework. Numerical validations on 27-, 33-, and 69-bus test feeders demonstrate cost-efficient conductor configurations. A multi-objective analysis is employed to construct the Pareto front, offering trade-offs between investment and operating costs. The impact of distributed energy resources (DERs) is also assessed, showing cost reductions when said resources provide reactive power support. The results confirm that the proposed MINLP approach outperforms conventional metaheuristics in terms of accuracy and reliability. Full article

With the evolvement of the coal marketplace and massive growth in renewable resource power, conventional coal-fired generation is facing challenges in the operation of fluctuating loads and varying coal characteristics. The intent of this study is to predict carbon emissions from coal-fired power plants during load cycling and the operation of varying coal characteristics. The given correlation was revised by adding a new nitrogen term and using thermodynamic data from the latest JANAF tables. On the basis of the revised correlation, the quantitative impact of each element composition of coal on the carbon emission factor was worked out according to first-order Taylor series approximation. The O/C and H/C ratio of coal at the lowest carbon emission factor was evaluated in the VAN Krevelen diagram, showing that coals have the lowest carbon emission factor value of roughly 23.25 kg/GJ GCV at atomic O/C and H/C ratio values of about 0.08 and 0.98, respectively. Correlations of carbon emission with the proximate analysis of coal were established through stepwise linear regression using 247 coals for power generation. Based on the varying nature of the net heat rate with load condition expressed by the generic model derived from 11 typical units in-service, the impact of coal and load cycling on carbon emission was captured with a developed equation. Linking the above investigation to a study in a thermal power unit with a rated output of 1000 MW shows that the total variation of carbon emission due to the combined effect of coal and load cycling could be 27.44% if the unit cycles at 35% to 100% rated output with coal normally varying in the present context. Full article

Polysiloxanes with silver nanoparticles (Ag NPs) have garnered attention for their distinctive physicochemical properties, which make them promising candidates for advanced material applications. This study presents a systematic investigation into the thermal properties and degradation mechanisms of polysiloxane/Ag nanocomposites, emphasising the innovative incorporation of Ag NPs directly into polysiloxane networks via in situ reduction of Ag⁺ ions by Si-H groups. Six polysiloxane matrices were synthesised by hydrosilylation of poly(methylhydrosiloxane) (PMHS) or poly(vinylsiloxane) (polymer V₃) with three cross-linking agents of varying molecular structures and functionality. Thermogravimetric analysis combined with mass spectrometry revealed that the introduction of Ag NPs alters the thermal properties of polysiloxane networks, primarily affecting the redistribution of Si bonds that occurs during the pyrolysis of these systems. Monitoring the pyrolysis process using FTIR spectroscopy allowed us to investigate the effect of the presence of Ag NPs on the degradation mechanism of the studied nanocomposites. The presence of the free-carbon phase and metallic silver phase in the Ag-containing silicon oxycarbide materials obtained was confirmed by Raman spectroscopy and XRD analyses, respectively. These findings demonstrate the possibility of fabricating Ag/SiOC materials with ceramic residues in the range of 43 to 84%. This work provides new insights into the thermal behaviour of polysiloxane/Ag nanocomposites and underscores their potential for high-performance applications in thermally demanding environments. Full article

Coal remains one of the most used solid fuels for heat and electricity generation but burning coal releases large amounts of CO₂ into the urban atmosphere in addition to harmful substances. In order to reduce the consumption of solid fossil fuels, it is necessary to search for fuels capable of replacing coal in terms of its thermal and environmental characteristics. One of the best alternative fuels is biomass, which is considered carbon neutral, but its thermal characteristics are worse than those of solid fossil fuels. In this work, an alternative to coal was studied for the first time, which was semi-coke, obtained by gasification at a temperature of 700–900 °C, the heat of combustion of which turned out to be higher than that of biomass before thermal treatment by 75%. We also studied fuel mixtures based on the resulting semi-coke. The aim of the work is to determine the main characteristics of combustion of semi-coke obtained from coniferous wood and mixtures based on them. The method of thermogravimetric analysis in oxidising medium at a heating rate of 20 °C/min was applied for the research. According to the results of this analysis, the ignition and burnout temperatures were determined, the combustion index was determined, the duration of coke residue combustion was determined, and synergetic interactions between the mixture components influencing the combustion characteristics were established. It was found that the ignition temperature of semi-coke is more than 50% higher than that of biomass and the burnout temperature is 10% higher. Adding 50% of biomass to semi-coke increases the combustion index by more than 30% and decreases the ignition temperature and burnout temperature. The mixture components synergistically interact with each other during combustion to reduce the value of maximum mass loss rate. It was found that the atomic ratios of O/C and H/C in semi-coke are lower than in biomass before gasification. Full article