Search Results (756)

Silicone rubber is an important external insulating material for composite bushings, composite insulators, and other power equipment. During long-term service, it is inevitably exposed to coupled environmental and electrical stresses, such as elevated temperature, moisture ingress, strong electric fields, and partial discharge, which may lead to hydrophobicity loss, surface chalking, crack propagation, and particle shedding. To reveal the microscopic degradation mechanism of silicone rubber under complex operating conditions, a molecular model of methyl vinyl silicone rubber was constructed using Materials Studio. A stable silicone rubber molecular structure was obtained through crosslinking, geometry optimization, and ensemble relaxation. Subsequently, a reactive molecular dynamics simulation system under coupled temperature–humidity–electric field conditions was established using LAMMPS and the ReaxFF reactive force field. Different temperature gradients, electric field intensities, and aging–recovery stages were designed to investigate the degradation behavior of silicone rubber. The evolution of the maximum carbon content, maximum silicon content, carbon-containing decomposition products, and typical small-molecule products, including H₂, H₂O, CH₄, C₂H₂, C₂H₄, and C₂H₆, was statistically analyzed. In addition, atomic trajectory tracking was performed to clarify the processes of methyl group detachment, Si-O bond cleavage, water molecule participation, and molecular chain reconstruction. The results show that high temperature mainly promotes methyl group detachment from side chains and fracture of the siloxane main chain, while a strong electric field accelerates the decomposition process and induces the transformation of long siloxane chains into shorter chains. Water molecules can react with broken siloxane chains to form hydroxyl-containing structures, making the structural degradation partially irreversible. The degradation process of silicone rubber under coupled temperature–humidity–electric field stress can be summarized as side-chain detachment, main-chain scission, water-assisted reactions, free-radical recombination, and local molecular aggregation. This study provides a molecular-level theoretical basis for aging mechanism analysis, condition assessment, and lifetime prediction of composite external insulating materials. Full article

Stable control of the main combustion chamber temperature is critical for pollutant emission compliance, energy recovery, and equipment longevity in municipal solid waste incineration (MSWI). However, the response delays from manipulated variables such as primary air, secondary air, and feed rate to the furnace temperature span from seconds to tens of minutes, and a uniform-delay assumption is inadequate to characterize the true response lag. Moreover, without an action-smoothing constraint, optimizers tend to produce abrupt control commands that destabilize the temperature trajectory. Using real industrial distributed control system (DCS) data from a full-scale grate furnace, this paper develops a prediction–decision collaborative control framework. In the prediction module, mutual information (MI) is used to identify the optimal delay of each manipulated variable separately, and the time-aligned manipulated variables together with a low-order autoregressive component serve as input to XGBoost and yield a prediction RMSE of 6.85 °C with an $R^2$ of 0.9845. In the decision module, a normalized smoothing penalty is incorporated into the fitness function of particle swarm optimization (PSO) to constrain the step-to-step variation in manipulated variables. Offline predictor-in-the-loop simulation on the test set shows that, compared with a multi-loop PID controller, the proposed method reduces the standard deviation of the furnace temperature tracking error by about 35% (from 5.80 °C to 3.80 °C), and lowers the mean tracking error to 3.65 °C while improving actuator smoothness over both unconstrained PSO and a genetic algorithm. The framework provides a collaborative-control design for pre-deployment evaluation of data-driven controllers in MSWI operation. Full article

Gallotia simonyi and G. bravoana are large lacertids inhabiting the islands of El Hierro and La Gomera, respectively, in the Canary Archipelago. Both species are critically endangered, but over the last several decades, they have been bred in outdoor terraria (G. simonyi since the 1990s and G. bravoana since 2000). In this study: (1) we describe all procedures carried out in the breeding centres and quantitatively analyse the long-term trajectory of breeding success throughout the study period; (2) we examine whether any parental individuals or specific pairs had a stronger influence on the number of successfully hatched offspring; (3) we report the trials of reintroducing individuals into the wild on each island in different years; (4) we provide information on several predator (cat-control) campaigns conducted on each island; (5) we detail the veterinary protocols and the results obtained when assessing the health status of breeding lizards; and (6) we report several educational activities carried out on each island. Gravid females laid eggs in suitable laying boxes; the eggs were then kept inside incubators with controlled temperature and humidity until hatching. Breeding produced 1267 offspring during the years considered for G. simonyi and 499 for G. bravoana. The mean NEL was 8.8 for G. simonyi and 5.2 for G. bravoana, and the mean HO was 6.4 and 3.54, respectively. Both NEL and HO were significantly higher in G. simonyi than in G. bravoana. NEL was significantly influenced by species and year, and by female snout–vent length (SVL) as a covariate, but not by male SVL. HO was significantly affected by year and by both male and female SVL, but not by species. There were significantly higher or lower values of both variables in specific years, but no clear long-term trend. Some breeding pairs had a greater influence on the dependent variables. Reintroduction into the wild has resulted in a currently stable population of G. simonyi on a small islet off the north-western coast of El Hierro, and some individuals are still present at an inland reintroduction site. For G. bravoana, some live specimens have recently been detected at a new reintroduction site. We conclude that: (1) captive breeding has been successfully carried out over the years in both centres; (2) there have been significant differences between the two species in NEL and HO; (3) female SVL was significantly related to both NEL and HO; and (4) reintroduction attempts have been only partially successful in each species. Veterinary monitoring revealed high dehydration tolerance, seasonal fluctuations in microbial flora, previous mineral imbalances that were corrected by improved nutrition, and effective parasite control that maintained overall lizard health. Except for a few individuals, most lizards were in good health. Full article

Long-term ichthyoplankton time series provide an effective framework for understanding how marine communities respond to environmental variability across temporal scales. We analyzed larval fish assemblage dynamics in the central Mexican Pacific under contrasting seasonal hydrographic conditions and ENSO phases using multivariate analyses, indicator species analysis, clustering, and generalized additive models. Environmental variability exhibited a hierarchical structure, with recurrent seasonal changes in sea surface temperature (SST) and coastal upwelling intensity (CUI), whereas the Oceanic Niño Index (ONI) varied mainly at the interannual scale. Significant differences in assemblage composition were detected among ENSO–seasonality regimes. Distance-based redundancy analysis showed that the primary compositional gradient was associated with seasonal hydrography, while secondary variation reflected ENSO-related interannual shifts. Species responses were expressed primarily through shifts in relative dominance rather than wholesale species replacement, indicating that assemblage reorganization was largely driven by changes in the relative contribution of recurrent taxa. This pattern highlights the role of seasonal hydrography as the primary environmental filter structuring the assemblage, whereas ENSO variability acts mainly as a secondary modulator of species dominance and community trajectories. Consequently, interannual climate anomalies influenced the relative importance of species without substantially redefining the underlying species pool. These findings improve the understanding of plankton community responses to climate variability in the tropical eastern Pacific. Full article

This study investigates the population dynamics and seasonal reproductive patterns of Gambusia holbrooki, an invasive fish threatening biodiversity within arid springs of the Edgbaston Spring complex in Queensland, Australia. Using daily aging techniques, we uncover critical life history traits that inform targeted species management. Our findings reveal marked sex-specific mortality rates, with males exhibiting higher mortality than females, a pattern consistent with findings from Tasmania. Reproductive activity peaks were observed between September and November, but persisted throughout the year, excluding January and April of 2020, likely due to elevated water temperatures during these months. Growth modeling identified the power function as the best fit for describing G. holbrooki growth trajectories. These insights highlight the importance of seasonally informed control strategies to mitigate the ecological impact of this pest species. The study provides essential data to support conservation efforts and guide effective management of invasive fish in fragile arid spring ecosystems. Full article

Trajectory data is valuable for applications such as urban planning, but its public availability is often limited by privacy concerns and data collection costs. While recent diffusion models have shown promise in generative tasks, existing methods rarely integrate personalized conditioning with road network constraints. As a result, they struggle to simultaneously achieve personalized mobility modeling and high road-network spatial validity, resulting in limited trajectory quality. In this paper, we propose Sem-RoadDiff, a symmetry-aware dual-guided diffusion model for personalized and road network-constrained trajectory generation. Specifically, our model incorporates two key components. First, we design a semantic preference guidance mechanism to encode user history into a preference-weighted user embedding using a temperature-scaled softmax. This enables the model to capture user-level mobility patterns without directly using raw trip-level records as generation conditions. Second, we introduce a road-aware mechanism to improve overall spatial validity, employing a spatial validity loss derived from the User Mobility Transition Graph. From a symmetry perspective, Sem-RoadDiff aims to preserve distributional symmetry between real and generated trajectories while respecting the inherent asymmetry of directed road-network transitions. Extensive experiments on the Geolife and Porto datasets demonstrate that our approach improves trajectory distributional fidelity compared with the evaluated baselines and improves road-segment connectivity over the diffusion-based baseline. Full article

In this study, the influence of thermal loading in a supersonic flight environment on the mechanical stiffness of elastic structures and the corresponding aeroelastic stability limits is investigated analytically. Recognizing that elevated temperatures inherently alter constituent elastic properties, a temperature-dependent continuous elasticity framework is incorporated directly into the governing differential operators of the structural domain. The macro-mechanical behavior of representative panel- and wing-type elements is modeled utilizing the Euler–Bernoulli beam formulation, while high-speed supersonic aerodynamic effects are represented through linearized first-order piston theory. The continuous spatial displacement fields are discretized by means of a modal expansion, and the coupled aeroelastic system is subsequently transformed into a finite set of dynamic state-space equations using the Ritz–Galerkin truncation method. The numerical and analytical outputs demonstrate that aerothermal softening not only induces continuous erosion in the material stiffness but also directly modulates the aeroelastic pole trajectories, thereby prematurely contracting the safe supersonic flight envelope. The primary novelty of the proposed framework lies in the derivation of explicit analytical expressions that directly map temperature-dependent stiffness variations onto supersonic aeroelastic instability boundaries. Because this approach is formulated in a generalized analytical form, it can be applied across diverse material systems, geometric profiles, and thermal conditions with reduced computational overhead compared to full fluid–structure interaction solvers, thereby providing a theoretical basis for preliminary stability assessment of supersonic aerospace configurations operating under high-temperature conditions. Full article

High-nickel NCA/Si–C 21700 cells exhibit strongly condition-dependent degradation, but the coupled influence of temperature and rate on electrochemical, thermal, and structural evolution remains insufficiently resolved. Here, Samsung INR21700-50E cells were aged under a 3 × 3 matrix of ambient temperatures (0, 23, and 40 °C) and C-rates (0.5C, 1C, and 2C). Periodic reference performance tests were used to track capacity, 10 s direct-current internal resistance, electrochemical impedance, pseudo-open-circuit voltage, differential voltage/incremental capacity behavior, heat generation, and post-mortem morphology. Guided by the hypothesis that temperature and rate history change not only the speed but also the dominant pathway of aging, the results show that both ambient temperature and the charge/discharge rate program govern the aging trajectory. Low-temperature cycling accelerates capacity loss and resistance growth through severe polarization and lithium plating, indicating dominant loss of lithium inventory. High-temperature operation promotes interfacial side reactions, impedance rise, and cathode structural degradation, leading to stronger loss of active material at later stages. An increasing C-rate amplifies these effects by raising overpotential and thermal load. Heat generation power increases markedly with aging and depends strongly on temperature–rate history. Scanning electron microscopy confirms cathode cracking, anode surface film thickening, and separator degradation under severe conditions. These experimental indicators are integrated into a mechanism-aware diagnostic framework that maps capacity retention, DCIR/EIS parameters, ICA/DVA indices, and heat generation metrics to dominant aging modes, supporting BMS state-of-health estimation, lifetime prediction, thermal management, and second-life screening of high-nickel NCA cells. The condition-averaged trajectories are further converted into a semi-empirical aging law that links capacity loss, resistance growth, and heat generation increase for BMS-oriented lifetime prediction. Full article

Assessing the contribution of tropical cyclones to regional precipitation variability is essential for understanding the associated hydrometeorological benefits and risks. This study quantifies the contribution of tropical cyclones to annual precipitation in the northernmost part of South America from 2016 to 2025, utilizing data from surface rain gauges. Simulations using the Weather Research and Forecasting (WRF) model, configured with 2 km grid spacing and 38 vertical levels, estimate the influence of relative humidity at 850 hPa and ambient temperature at 500 hPa on precipitation over the continental region when each convective system is nearest to the coastline. During Hurricanes Matthew (2016) and Melissa (2025), contributions to the annual average precipitation reached 51% and 47%, respectively, with the highest values observed near the northern South American coastline. The contributions of Harvey (2017), Iota (2020), Julia (2022), and Beryl (2024) to annual precipitation were 0–26%, 0–18%, 0–12%, and 0–19%, respectively. Precipitation distribution was heterogeneous during the passage of tropical storms. The extent of accumulated precipitation was influenced by the cyclone’s trajectory and proximity to mountainous regions. Patterns of relative humidity at 850 hPa did not correspond to a uniform precipitation distribution. Between 6% and 30% of rain gauges did not record precipitation during the analyzed tropical cyclone events. These findings highlight that tropical cyclone-induced precipitation is strongly influenced by complex interactions between atmospheric dynamics and topography. Future research should assess the contributions of these systems to groundwater and surface reservoirs that support indigenous communities in rural areas. Full article

The contact performance of automotive airbag electrical connectors directly affects the stable conduction of the initiator circuit, yet sufficient failure data are difficult to obtain for such long-life safety-critical components. This study develops a degradation model for connectors with stainless-steel pins, beryllium-bronze sockets, and Ni/Au composite coatings, using the contact resistance increment as the degradation measure. Considering the accumulation of oxidation corrosion products under thermal stress, as well as the local film rupture and re-oxidation induced by fretting wear under combined temperature-vibration stress, a nonlinear time scale t^α is introduced to describe the nonlinear growth of contact resistance. A random-drift nonlinear Wiener process is then constructed: the diffusion term represents local fluctuations within each sample trajectory, while the random drift rate captures growth-rate differences among samples. Parameter estimation was performed using degradation data obtained from 160 °C high-temperature and 160 °C temperature-vibration accelerated degradation tests. The estimation results show that the stress-class-specific time-scale model better reflects the different degradation mechanisms than a common time-scale model, and that the temperature-vibration group exhibits higher resistance growth and stronger trajectory fluctuations. Model diagnostics support the description of the main increment distribution and sample-to-sample differences, while EDS and XPS results provide supplementary evidence for oxidation-related surface composition changes and coating-state evolution. Full article

Global climate change profoundly impacts the geographical distribution patterns and evolutionary dynamics of plants. As a vital ornamental and ecological shrub native to the temperate regions of the Northern Hemisphere, the wild germplasm resources of Weigela florida are facing dual threats from habitat fragmentation and climate warming. To elucidate the biogeographical mechanisms underlying the species’ responses to climate change and to formulate scientific conservation strategies, this study simulated the spatiotemporal dynamics of suitable habitats for W. florida across key historical periods spanning the Late Pliocene (~3.3 million years ago), Quaternary (~2.58 million years ago), the current period, and future climate scenarios using an optimized Maximum Entropy ecological niche model, and further tracked the migration trajectories of its spatial centroids. The results indicate that precipitation conditions, dry-season temperatures, and temperature seasonality are the dominant environmental factors limiting the distribution of wild W. florida. During the glacial–interglacial cycles, the area of its suitable habitat fluctuated significantly. Notably, the Korean Peninsula and the southern part of Northeast China maintained high habitat suitability across all geological historical periods, serving as long-term stable Quaternary glacial refugia for the species. Under various future climate scenarios, the total suitable habitat area of W. florida generally exhibits a shrinking trend, with habitat loss primarily concentrated at the western and southern edges of its distribution range. In the future, its spatial centroid shows a significant tendency to migrate towards higher latitudes (northeastward) to track suitable climatic niches. This study clarifies the macroscopic driving mechanisms behind the habitat dynamics of wild W. florida, providing critical spatial planning guidance for the refined evaluation and long-term sustainable utilization of its germplasm resources. Full article

Amid accelerating global environmental change, assessing ecological vulnerability is critical for sustainability science. Focusing on the Yellow River Source Region (YRSR)—a key water source and ecological shield in China—this study develops an integrated assessment system based on the “Pressure–State–Response” (PSR) framework, incorporating 29 indicators. A combined weighting approach integrating analytic hierarchy process (AHP) with entropy-based objective weighting characterizes the spatiotemporal patterns, drivers, and future trajectories of ecological vulnerability. Key findings reveal: (1) heterogeneous warming–wetting trends with stronger humidification in the south and relative stability in the north drive divergent hydrological responses, highlighting the limitations of single-climate metrics in explaining vulnerability dynamics; (2) vulnerability patterns are primarily shaped by climatic factors—especially temperature and potential evapotranspiration—with anthropogenic pressures serving as secondary modulators, reinforcing the foundational role of thermal and moisture regimes in alpine ecosystem resilience; and (3) scenario projections consistently identify the northeast as a persistently high-vulnerability zone, yet show that balanced socioeconomic development can reconcile ecological protection with development needs. Based on these insights, a four-tier ecological zoning scheme and a governance framework comprising three strategies—strict conservation, adaptive regulation, and sustainable utilization—are proposed. This work offers actionable scientific guidance for tailored ecological conservation in the YRSR and contributes methodological advancements for vulnerability assessment and adaptive management of high-elevation ecosystems globally. Full article

In complex wellbore environments, traditional ball-drop, cable, and electromagnetic sliding sleeve communication methods face reliability problems caused by high temperature, high pressure, complex trajectories, and signal attenuation. This paper presents a pressure-wave-based downhole communication and sliding sleeve activation system. Surface pressure variations generated by pump displacement and pressure relief are used to transmit encoded commands through the wellbore fluid and realize non-contact activation of the downhole sliding sleeve. A wellbore pressure-wave propagation model is established, and the effects of well depth, wellbore diameter, pump displacement, pump-on time, pressure-relief timing, and pressure-relief duration on bottom-hole pressure response are analyzed. A bipolar non-return-to-zero coding strategy combined with a constant-threshold decoding method is proposed to improve signal recognizability and robustness. Simulation results show that for a 5000 m wellbore and a pressure-wave velocity of 1100–1300 m/s, the signal transmission delay is approximately 4.2 s, and the bottom-hole pressure responses induced by pump displacement and pressure-relief valve operation can be clearly distinguished. Laboratory tests at 150 °C and 120 MPa showed that the sliding sleeve achieved a 110 mm stroke and 100% opening ratio in four repeated activation tests. In the field test, three pressure command cycles between 10 MPa and 40 MPa successfully triggered the sliding sleeve, followed by a squeeze test with a displacement of 0.3–0.7 m³/min and a maximum pressure of approximately 60 MPa. The results demonstrate that the proposed system provides a feasible and reliable pressure-wave communication method for downhole sliding sleeve activation in deep and long horizontal wells. Full article

With the continuous advancement of thrust-to-weight ratios in modern aero-engines, turbine inlet temperatures have reached levels that far exceed the thermal endurance limits of conventional superalloys and emerging ceramic matrix composites (CMCs). Consequently, thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs) have become indispensable multifunctional systems for hot-section component protection. This review systematically delineates the evolutionary trajectory of TBC/EBC systems, transitioning from traditional yttria-stabilized zirconia (YSZ) and simple silicates to advanced multi-rare-earth-doped oxides, A₂B₂O₇ pyrochlore structures, and high-entropy ceramic systems. A critical comparative assessment is provided regarding their phase stability, thermal-physical properties, and durability challenges above 1200 °C. Furthermore, this paper provides an in-depth analysis of high-temperature degradation mechanisms, focusing on the thermochemical and thermomechanical interactions under calcium-magnesium-alumino-silicate (CMAS) attack, water-oxygen corrosion, and molten salt infiltration. By synthesizing current research gaps, we highlight the trade-offs between low thermal conductivity, high toughness, and environmental resistance. Finally, a strategic roadmap for next-generation coatings is proposed, emphasizing the integration of high-entropy material design, multi-scale structural optimization, and AI-driven life prediction models to meet the stringent reliability requirements of future propulsion systems. Full article

Chub mackerel (Scomber japonicus) is a commercially important pelagic species in the northwest Pacific Ocean. Accurate identification of its fishing grounds can provide a more robust and targeted scientific basis for fishery management and ecological research. Based on fishing effort and five environmental factors (i.e., sea surface temperature [SST], chlorophyll-a concentration [CHL], SST gradient [GSST], sea surface height [SSH], and current speed), this study developed a Classification and Regression Tree (CART) rule-guided MaxEnt model. Specifically, rules generated by the CART model were first extracted and then incorporated as constrained feature functions into MaxEnt for model training. To select the optimal model scheme, four combinations of rule compositions and feature function outputs were designed, and model performance on the validation dataset was evaluated using ROC curves. Finally, the model was further verified with in situ environmental and fisheries data from April to November 2024. Results showed that the predicted fishing grounds were highly aligned with the actual monthly fishing grounds in 2024, and the predicted migration routes matched the movement trajectory of fishing vessels. The model also exhibited satisfactory performance, achieving an average AUC of 0.722 ± 0.033, a sensitivity of 0.604, a specificity of 0.834, and a negative predictive value (NPV) of 0.978. In conclusion, the CART rule-guided MaxEnt model, integrating the interpretability of CART and the predictive power of MaxEnt, effectively predicts the spatial distribution of chub mackerel fishing grounds in the northwest Pacific Ocean, providing technical support for fishery management and ecological research. Full article