Search Results (3,469)

Lithium-ion batteries (LIBs) are pivotal for energy storage in electric vehicles and renewable systems, but how to effectively monitor their conditions and ensure their operational reliability is still a concern today. This study employs electrochemical impedance spectroscopy (EIS) to systematically investigate the evolution of impedance characteristics in nickel–cobalt–manganese oxide (NCM) lithium-ion batteries (LIBs) under varying states of charge (SOCs), states of health (SOHs), temperatures, and mechanical compression displacements. Results reveal that higher SOC and temperature reduce impedance by enhancing ion kinetics and interfacial activity, with $R_{ct}$ (charge transfer resistance) exhibiting a U-shaped dependence on SOC, minimized at 40–60%. As SOH declines from 100% to 80%, $R_{SEI}$ (SEI film resistance) and $R_{ct}$ increase progressively, reflecting SEI thickening and electrode degradation. Mechanical compression (0–8 mm) elevates all resistances, particularly $R_{ct}$ at high SOC, due to structural deformation and hindered diffusion. DRT (distribution of relaxation times) spectra highlight amplified low-frequency peaks with aging and low SOC, underscoring diffusion limitations. These findings elucidate multi-scale failure mechanisms, from interfacial polarization to structural instability, providing a framework for non-invasive health monitoring and lifetime prediction. Full article

With the expansion of global oil and gas resource exploration and development into deep and ultra deep layers, the efficient development of deep carbonate rock fracture cave reservoirs has become the key to ensuring energy security. However, this type of reservoir commonly faces high temperatures, high salinity, and extremely strong heterogeneity, leading to increasingly severe water content spikes caused by dominant water flow channels. Although the existing traditional inorganic plugging agent has good temperature resistance, it has the defects of great brittleness and easy cracking, while the organic polymer gel is prone to degradation failure under high temperature and high salt environments. In order to solve the above problems, a new biochar-enhanced inorganic composite gel system was constructed by using biochar prepared from agricultural and forestry waste pyrolysis as a functional enhancement component. Through rheological testing, high-temperature and high-pressure mechanical experiments, long-term thermal stability evaluation, and dynamic sealing experiments of fractured rock cores, the reinforcement and toughening laws and rheological control mechanisms of biochar on inorganic matrices were systematically studied. Research has found that a biochar content of 0.5 wt% can significantly improve the micro pore structure of the matrix. By utilizing its micro aggregate filling effect and interfacial chemical bonding, the compressive strength of the solidified body can be increased to over 2 MPa, and there is no significant decline in strength after aging at 130 °C for 30 days. More importantly, the unique “adsorption slow-release” mechanism of biochar effectively stabilizes the hydration reaction kinetics at high temperatures, extending the solidification time of the system to 15 h and solving the problem of flash condensation in deep well pumping. This system exhibits excellent shear thinning characteristics and crack sealing ability, and presents a unique “yield reconstruction” toughness sealing feature. This study elucidates the multidimensional strengthening mechanism of biochar in inorganic cementitious materials, providing technical reference for stable oil and water control in deep fractured reservoirs. Full article

Understanding spatiotemporal variation in soil CO₂ flux (FCO₂) along elevational gradients is essential for predicting carbon–climate feedback in alpine ecosystems. However, how temperature- and moisture-related factors jointly regulate daily-scale FCO₂ and how their contributions vary with elevation remain unclear, particularly in the Sejila Mountains (Southeastern Tibetan Plateau). We conducted continuous in situ measurements of daily-scale FCO₂, air temperature (Ta), relative humidity (RH), soil temperature (ST, 0–10 cm), and volumetric soil water content (SW) across five elevational bands (3000–4200 m) in 2024–2025. Across both years, FCO₂ showed a unimodal seasonal cycle and a robust nonmonotonic spatial pattern, with the highest efflux at 3000 and 4200 m and peak rates exceeding 5.0 µmol CO₂ m⁻² s⁻¹. Cumulative carbon loss at 4200 m (909.90 g C m⁻²) exceeded that at mid-elevation sites. Linear mixed-effects models identified Ta as the most consistent positive predictor; the ST × SW interaction was not significant, indicating that temperature and moisture effects are largely additive at the daily scale. Piecewise regression revealed nonlinear SW thresholds (θ) in the FCO₂ response, with θ varying nonmonotonically with elevation. Multiple linear regression further showed that thermal predictors (Ta, ST) explained substantially more variance than moisture predictors (RH, SW), and the relative importance of thermal drivers increased with elevation. These results challenge the common expectation of a monotonic decline in soil respiration with elevation and suggest that, when SW remains above critical thresholds, warming may amplify soil carbon losses at high elevations on the Tibetan Plateau. Full article

Against the backdrop of ongoing climate change, the Qinghai–Tibet Plateau, a region highly sensitive to climatic variation, exhibits intricate spatiotemporal patterns in reference crop evapotranspiration (ET_O), with significant implications for regional water-resource planning. This study selected four agro-climatic zones across the plateau region (TSA, TSH, TAZ, and WCH). Long-term daily observations from 28 meteorological stations were used to estimate ET_O via the FAO 56 Penman–Monteith equation. This extensive dataset enabled robust trend analysis using the Mann–Kendall test, alongside a cloud-model framework, and analyses of sensitivity and contributions to evaluate ET_O’s spatiotemporal evolution, its distributional uncertainty, and the underlying drivers. Results reveal pronounced regional heterogeneity in the interannual variability of ET_O. Annual ET_O declined in TSH and TSA (trend rates of −1.12 and −6.58 mm·10a⁻¹, respectively) and increased in TAZ and WCH (15.76 and 10.74 mm·10a⁻¹, respectively). At monthly and seasonal timescales, ET_O exhibited an unimodal pattern, with the greatest stability in winter and spring and lower stability in summer and autumn. The cloud-model parameter He indicates that ET_O stability is greatest in TSH and weakest in WCH, with He values of 7.15 and 12.29 mm, respectively. Contribution-rate analyses identify T_max and T_mean as the principal determinants of rising ET_O across all study zones, reflecting the largest individual contributions. Temperature-related factors together account for the majority of ET_O variability across the regions, with their absolute contributions ranging from 5.61% to 8.63%, well above those of aerodynamic factors (0.62–1.78%). Stability assessments indicate that ET_O is generally more unstable than its meteorological drivers, with substantial regional disparities, implying that ET_O evolution cannot be explained by a single controlling factor. Overall, the study characterizes the uncertainty in ET_O variations under complex terrain, highlights the value of the cloud model for refined hydrological assessments, and provides a scientific basis for adaptive agricultural water-resource management in the region. Full article

Potential evapotranspiration (PET) and water balance (WB) are key indicators of hydroclimatic conditions and water availability, particularly in arid and semi-arid regions. This study investigates the interannual variability, long-term trends, and abrupt regime shifts in annual PET and WB across Saudi Arabia using multi-station observational data spanning 1985–2022. PET was estimated using a temperature-based approach suitable for data-scarce arid environments, and WB was calculated as the difference between precipitation and PET. Non-parametric statistical methods were applied to assess trend magnitude and significance, while Pettitt’s change-point test was used to identify abrupt shifts at both regional and station scales. The main findings show a widespread and spatially coherent increase in atmospheric evaporative demand, with predominantly positive PET trends at both regional and station scales, accompanied by persistently negative and increasingly declining WB values, indicating a long-term intensification of water deficit across much of the country. Spatial patterns of PET and WB closely follow gradients in energy availability and temperature, confirming the dominant influence of warming-driven processes on hydroclimatic conditions in this arid environment. Change-point analysis identifies a statistically significant regional hydroclimatic regime shift during the late 1990s, characterized by an abrupt increase in PET and a concurrent deterioration of WB, marking the onset of a more water-limited climatic regime. At the station scale, the timing and significance of detected change points display pronounced spatial heterogeneity, reflecting the modulation of regional climatic forcing by local climatic and geographic factors. Overall, the results demonstrate that increasing evaporative demand, rather than precipitation variability alone, has become a primary control on water availability across Saudi Arabia, highlighting the importance of explicitly accounting for hydroclimatic non-stationarity in water resource assessment and long-term planning under continued warming conditions. Full article

Climate change is increasingly affecting groundwater resources in the Carpathian Basin, while rising temperatures are likely to increase irrigation demand and pressure on aquifers. We assessed climate- and pumping-driven impacts on the Nyírség recharge–discharge system (north-eastern Hungary) by combining shallow groundwater monitoring (1970–2022) with hydroclimate indicators from CHIRPS precipitation and ERA5-Land air temperature and snow depth (1981–2024). Using these datasets, we developed and calibrated a MODFLOW groundwater-flow model for representative wet (2010) and dry (2022) conditions, incorporating permitted abstraction and scenario-based estimates of unregistered pumping. We then ran scenario simulations to evaluate mid-century (2050) conditions and managed aquifer recharge (MAR) options. Precipitation exhibits strong interannual variability, but the region shows marked warming and a pronounced decline in snow storage, implying reduced cold-season buffering and higher evaporative demand. Simulations reproduce the observed post-2010 decline in shallow groundwater, with the largest decreases in higher-elevation recharge areas, whereas increased pumping mainly intensifies localized drawdown near major well fields. Scenario results indicate that climate-driven reductions in recharge dominate basin-scale declines by 2050, while MAR provides primarily local benefits; direct subsurface injection performs best among the tested options. These findings support practical groundwater management by prioritizing measurable and enforceable abstraction (including unregistered withdrawals), demand-side irrigation efficiency and adaptive caps in recharge areas, and targeted subsurface MAR where source water and infrastructure are available. Full article

Crosslinked polyethylene (XLPE) is a widely used cable insulation material for power cables at various voltage levels, offering excellent electrical, mechanical, and thermal stability. However, during the continuous extrusion moulding process, prolonged shear action and localized temperature accumulation can easily induce premature crosslinking. This leads to a decline in melt rheological properties and reduced processing stability, as well as having an adverse effect on the microstructure and overall performance of the formed insulation layer. This study systematically investigated the impact of shear-induced pre-crosslinking on the mechanical properties and dielectric characteristics of XLPE cable insulation materials through experimental testing methods. The experimental results demonstrate that, while premature crosslinking has a minimal effect on mechanical properties, it significantly deteriorates dielectric performance, as evidenced by increased conduction current, reduced breakdown strength, and compromised microstructural integrity. These findings suggest that, to improve the quality and reliability of XLPE cable production, engineering designs should prioritize controlling the pre-crosslinking process to ensure stable dielectric performance. Full article

Under global climate change, frequent droughts threaten ecosystem functions, but how drought characteristics affect ecosystem resilience remains unclear. Focusing on the Dongjiang River Basin, China, we identified drought events at an 8-day scale from 2000–2024 using multi-source remote sensing and reanalysis data. The water use efficiency-based resilience index (R_de) was calculated, and a random forest model quantified the contributions of 21 potential driving factors. The model explained 68% of R_de variance (R² = 0.68, RMSE = 0.12). Downward shortwave radiation was the primary factor, followed by antecedent water use efficiency and soil moisture anomaly, with drought intensity and air temperature ranking fourth and fifth. All dominant factors exhibited nonlinear threshold effects: R_de decreased significantly after radiation exceeded ~110 W·m⁻²·(8d)⁻¹; R_de declined when standardized soil moisture anomaly fell below −2.0; and R_de increased sharply when drought intensity exceeded 12%. Drought intensity far outweighed duration and severity, establishing it as the key drought attribute. This study reveals the dominant drivers and their thresholds governing ecosystem resilience in the Dongjiang River Basin, providing quantifiable indicators for ecological drought early warning. Full article

To reduce vehicular emission pollution in cold regions and maximize sustainable development of transportation, AC self-heating of electric vehicles is acknowledged as an efficient approach to mitigate the decline in Li-ion battery performance under low-temperature conditions. This paper introduces a novel battery self-heating approach based on reconfiguration of the drive circuit, which is compatible with both preheating and on-route heating. The undesired torque generated by the heating current can be inherently nullified regardless of the rotor position. The control of heating and driving currents is entirely decoupled, facilitating straightforward adaptation to a range of heating strategies. Furthermore, a battery electro-thermal model is proposed and integrated with the drive system model to estimate the battery temperature evolution. Comprehensive experiments are designed to validate the operating principle and the accuracy of battery temperature estimation under various working conditions. The results present a high fidelity between the experimental data and the simulation outcomes. The root mean square errors of the predicted battery temperature under all the constant and combined driving conditions are less than 1 °C. Full article

During multi-layer commingled production of coalbed methane (CBM), fluid interference induced by interlayer pressure differences is a major constraint on productivity, representing a dynamic coupling process of reservoir pressure, temperature, and deformation. To elucidate this mechanism, we constructed a four-layer superimposed reservoir physical model using a self-developed large-scale true triaxial multi-field coupling test system, which reflects the geological conditions of the Eastern Yunnan and Western Guizhou region. We precisely regulated interlayer pressure differences and monitoring multi-physical parameters in real time to analyze the dynamic evolution of reservoir temperature, pressure, and deformation fields. The findings reveal that: (1) Increased interlayer pressure difference intensifies fluid interference in low-pressure reservoirs, causing abnormal pressure buildup. For example, when the pressure difference rose from 0.2 MPa to 0.6 MPa, the maximum pressure increase in Reservoir I grew from 1.03 MPa to 1.13 MPa. (2) The high-pressure reservoir (Reservoir IV) remained largely unaffected throughout production, with its temperature decline rate consistently correlated positively with pressure difference, indicating a distinct response behavior. (3) Reservoir deformation correlates positively with initial pressure. When the initial pressure of Reservoir II increased from 1.2 MPa to 1.6 MPa, its volumetric strain rose from 1.81‰ to 2.21‰, attributable to the combined effects of matrix shrinkage, elevated effective stress, and desorption-induced thermal cooling. This study demonstrates how interlayer pressure differences regulate the coupled evolution of reservoir pressure, temperature, and deformation, providing experimental evidence and theoretical support for identifying interference mechanisms and optimizing development strategies in CBM commingled production. Full article

Well spacing and reinjection rate are two critical parameters controlling the efficiency and sustainability of hot dry rock geothermal development. Taking the Yangbajing geothermal field in Tibet as the geological setting, permeability experiments were conducted on fractured rock masses under multiple operating conditions, and a three-dimensional fully coupled thermo-hydro-mechanical numerical model was established to systematically evaluate the effects of different well spacing–reinjection rate combinations on heat extraction performance. The experimental results show that axial stress is the dominant factor governing specimen deformation and seepage characteristics. Permeability decreases with increasing axial stress, exhibiting an initial sharp decline followed by a gradual reduction. The effect of temperature varies with axial stress level. Under low to moderate axial stress, permeability decreases monotonically with increasing temperature, whereas under high axial stress, it first decreases and then increases. The simulation results indicate that the production temperature remains relatively stable during the early stage of exploitation and subsequently declines, with the rate of decline increasing significantly as the reinjection rate increases or the well spacing decreases. In addition, an exponential positive relationship is identified between well spacing and the optimal reinjection rate. When a 10% decline in production temperature is adopted as the shutdown criterion, the optimal reinjection rate increases from 60 m³/h to 150 m³/h as the well spacing increases from 500 m to 800 m. Based on the simulation results, the theoretical installed capacity of the first deep reservoir in the Yangbajing geothermal field is preliminarily estimated to reach 31.8 MW. Full article

Urban areas in arid environments are increasingly affected by the urban heat island (UHI) effect, which intensifies thermal stress, disrupts ecological balance, and poses challenges for sustainable urban development. Understanding and predicting spatiotemporal variations in land surface temperature (LST) and land use dynamics is therefore critical for effective urban planning. This study develops a predictive framework for Riyadh, Saudi Arabia, using long-term Landsat time series data (1993–2023) and deep learning models to evaluate urban thermal patterns via the Urban Thermal Field Variation Index (UTFVI). Artificial Neural Networks (ANNs) with six hidden layers for LST and seven for UTFVI forecast future trends up to 2043. The results indicate that urban areas expanded by 521.62 km², increasing from 8.73% to 19.56% between 1993 and 2023, and are projected to reach 1509.40 km² (25.28%) by 2043, while vegetation coverage declined from 0.771% to 0.674%. The highest average summer LST increased from 56.73 °C in 1993 to 59.89 °C in 2023 and is predicted to rise to 60.79 °C by 2033 and 61.52 °C by 2043. Winter temperatures exhibited a comparable upward trend, rising from 30.75 °C to 32.33 °C in 2023 and projected to reach 34.48 °C by 2043. UTFVI analysis revealed a substantial expansion of weak thermal field zones, which covered 2778 km² in 2023 and are expected to reach 3018.44 km² (57%) by winter 2043, accompanied by a marked contraction of strong thermal field areas. The ANN models achieved a high predictive performance, with RMSE values of 0.759 (summer) and 0.789 (winter) for UTFVI and correlation coefficients of 0.91 and 0.89, respectively. Projections further indicate that, by 2043, approximately 39.31% of the study area will experience summer temperatures between 48 °C and 53 °C, compared to 5.59% in 2023. These findings highlight the accelerating interaction between urban growth and thermal intensification in arid cities. The proposed modeling framework provides a robust decision-support tool for urban planners and policymakers to mitigate UHI impacts and promote climate-resilient and sustainable urban development. Full article

High-concentration carbon monoxide (CO) produced by incomplete methane combustion in underground explosions is the primary cause of post-explosion fatalities, with typical concentrations (2–4%) far exceeding human tolerance limits. Unsupported Co₃O₄ catalysts were synthesized via a hydrothermal route and evaluated for post-explosion CO elimination under realistic mine-atmosphere conditions. The phase-pure spinel catalyst (crystallite size ~18 nm, S_BET = 68.5 m²/g) exhibited exceptional low-temperature activity with T₅₀ = 43 °C and T₉₀ = 59 °C under 10% O₂, and an apparent activation energy of 63 kJ/mol, substantially outperforming commercial Hopcalite (T₅₀ = 95 °C). In 20 L explosion vessel tests simulating 11% CH₄ combustion at a catalyst loading of 200 g/m³, CO was reduced from 2.85% to 0.32% (89% reduction), extending the escape time factor to k_es = 1.62. Continuous operation at 70 °C for 120 h maintained CO conversion above 96%, and three consecutive explosion cycles produced only a modest ~2% decline in activity, with post-test XRD confirming retention of the spinel phase. Mechanistic studies combining in situ DRIFTS and CO-TPD identify a Mars–van Krevelen pathway driven by surface Co³⁺ sites and reactive lattice oxygen. Full article

Carbon storage of terrestrial ecosystems is highly susceptible to land use/cover change (LUCC). In order to optimize land use patterns and advance the dual carbon goals (carbon peaking and carbon neutrality), it is imperative to clarify the role of LUCC in controlling regional terrestrial carbon storage. This study utilized a land use dataset spanning from 1990 to 2020 and incorporated 12 pivotal driving factors. Based on these data and factors, this study constructs four distinct future development scenarios: natural development scenario (ND), cropland protection scenario (CP), ecological protection scenario (EP), and urban development scenario (UD). By integrating the Integrated Valuation of Ecosystem Services and Trade-offs model (InVEST) with the Patch-Generating Land Use Simulation model (PLUS), this study simulated the dynamic changes in land use types and the spatiotemporal evolution of carbon storage in the Qinba Mountains (QBMs). The results revealed that between 1990 and 2020, built-up area and water area experienced substantial expansion with growth rates of 67.89% and 20.39%, respectively. In addition, cropland decreased by 3.09% and grassland decreased by 2.49%. Notably, cropland exhibited the most pronounced conversion intensity among all land use types during this period. Correspondingly, the total terrestrial carbon storage in the study area declined slightly from 7471.08 × 10⁶ t in 1990 to 7437.25 × 10⁶ t in 2020. Forestland dominated the regional carbon pool, accounting for an average of 47.67% of the total carbon storage over the three decades. Further analysis identified natural factors as the primary drivers of LUCC and associated carbon storage changes, with DEM exerting the greatest influence, followed by mean annual temperature and mean annual precipitation. Projection analyses for 2030 reveal divergent carbon storage outcomes across different land use scenarios relative to the 2020 baseline. Under the natural development (ND) and urban development (UD) scenarios, total carbon stocks are projected to decline by 37.63 × 10⁶ t and 19.99 × 10⁶ t, respectively. Conversely, implementation of conservation-oriented strategies yields substantial increases, with the cropland protection (CP) and ecological protection (EP) scenarios enhancing carbon storage by 16.87 × 10⁶ t and 13.07 × 10⁶ t, respectively. These findings underscore the critical role of protection-focused land use policies in strengthening ecosystem carbon sequestration capacity. The study provides a scientific foundation for formulating targeted forestry management policies and enhancing the terrestrial ecosystems’ capacity to act as carbon sinks in mountainous areas. Full article

As a result of global climate change, insects are increasingly being exposed to extreme temperature events; yet population-level variation in heat tolerance and its underlying mechanisms remain poorly understood. In this study, we investigated thermal adaptation in four geographically distinct populations of the invasive mealybug Dysmicoccus neobrevipes from southern China. The populations were subjected to acute heat stress across a gradient of temperatures where survival, fecundity, offspring viability, and sex ratio were quantified. We found pronounced geographic divergence in upper thermal limits: populations from warmer regions (Guangdong and Hainan) exhibited better survival, more stable reproductive output, and greater tolerance in offspring compared with populations from cooler regions (Guangxi and Yunnan). Thermal responses followed a nonlinear pattern, with moderate heat often enhancing performance, while temperatures above physiological thresholds triggered abrupt declines. Under heat stress, life-history strategies differed among populations, with some exhibiting stress-induced reproductive investment and others showing vulnerability across all traits. Importantly, acute heat exposure produced cross-generational effects, highlighting that parental thermal history can influence offspring performance. These results demonstrate that population-specific climatic adaptation, nonlinear physiological limits, and life-history trade-offs jointly shape thermal tolerance. Understanding these mechanisms provides a predictive framework for anticipating invasive pest expansion under future climatic warming and informs region-specific pest management strategy development. Full article