Search Results (42)

In this study, the PM_2.5 pollution transport budget in the atmospheric boundary layer (ABL) of Beijing–Tianjin–Hebei (BTH) and Chengdu–Chongqing (CY) was quantitatively evaluated from the perspective of horizontal and vertical exchange. Based on the aircraft meteorological data relay (AMDAR) observation data, the study found that the vertical exchange process of pollutants is mainly influenced by the combined effects of meteorological conditions and topographical factors. Meteorological factors determine the direction and intensity of the vertical exchange, while the complexity of the terrain affects the exchange pattern through local circulation and air flow convergence. The characteristics of the pollution transport budget between the BTH and CY regions show that the BTH region has a net output of pollutants throughout the year, while the CY region has a net input of pollutants. The total transport budget of the four typical representative seasons in BTH is negative. It indicated that BTH, as the region with the highest intensity of air pollution emission in China, is dominated by outward transport of air pollutants to surrounding regions. Due to the influence of topographic and meteorological conditions in the CY region, the air pollutants tend to accumulate in the basin rather than diffuse. The transport budget relationship of the four seasons is positive and the input of air pollutants can be obviously simulated. Combined with the results of the vertical wind profile, Beijing is more vulnerable to the prevailing cold air sinking in the northwest in winter, which is characterized by the inflow of the free troposphere (FT) into the ABL. As for Chongqing, it is blocked by mountains so that the gas convection at the top of the ABL is obvious. This horizontal convergence phenomenon induces upward vertical movement, which makes Chongqing show a strong characteristic of the ABL transport to the FT. Full article

Farmland use transition (FUT) not only reshapes agricultural production systems but also significantly impacts cross-regional carbon sink transfers in the grain trade. However, comprehensive studies exploring connections between FUT and grain carbon sink transfer (GCST) are limited. We constructed an indicator system and transformation framework for FUT by considering dominant and recessive dimensions. Moreover, we estimate GCST based on grain supply–demand balance and fixed carbon coefficients. Fixed effects and threshold models are employed to identify both linear and nonlinear relationships between FUT and GCST. Results show that FUT significantly reshapes carbon sink flows. In terms of dominant FUT indicators, cultivation land rate (CLR) and grain planting area proportion (GPAP) positively drive GCST by expanding the carbon sink supply and exporting ecological services. Regarding recessive FUT indicators, both grain yield per unit area (GYield) and pesticide-fertilizer intensity (PFI) promote GCST, highlighting the role of efficiency and inputs, while rural per capita disposable income (RPCDI) suppresses GCST due to agricultural marginalization. A grain yield threshold of 2.092 t/ha is identified. Below this value, FUT exerts substantial positive effects on GCST. Above it, the effects weaken. This study explains the relationship between FUT and ecosystem carbon sinks, providing a scientific basis for advancing green agriculture in karst mountainous areas. Full article

The mechanism for the upscale deposition of energy into the atmosphere from molecules and photons up to organized wind systems is examined. This analysis rests on the statistical multifractal analysis of airborne observations. The results show that the persistence of molecular velocity after collision in breaking the continuous translational symmetry of an equilibrated gas is causative. The symmetry breaking may be caused by excited photofragments with the associated persistence of molecular velocity after collision, interaction with condensed phase surfaces (solid or liquid), or, in a scaling environment, an adjacent scale having a different velocity and temperature. The relationship of these factors for the solution to the Navier–Stokes equation in an atmospheric context is considered. The scale invariant version of Gibbs free energy, carried by the most energetic molecules, enables the acceleration of organized flow (winds) from the smallest planetary scales by virtue of the nonlinearity of the mechanism, subject to dissipation by the more numerous average molecules maintaining an operational temperature via infrared radiation to the cold sink of space. The fastest moving molecules also affect the transfer of infrared radiation because their higher kinetic energy and the associated more-energetic collisions contribute more to the far wings of the spectral lines, where the collisional displacement from the central energy level gap is greatest and the lines are less self-absorbed. The relationship of events at these scales to macroscopic variables such as the thermal wind equation and its components will be considered in the Discussion section. An attempt is made to synthesize the mechanisms by which winds are generated and sustained, on all scales, by appealing to published works since 2003. This synthesis produces a view of the general circulation that includes thermodynamics and the defining role of turbulence in driving it. Full article

A deep interaction between groundwater and surface hydrology characterizes karst environments. These settings feature closed depressions, whose hydrological role varies depending on whether they have genetic and hydraulic relationships with overland–subsurface flow (epigenic) or deep groundwater circulation (hypogenic). Epigenic dolines and poljes are among the diagnostic landforms of karst terrains. In this study, we applied a hydrological criterion to map closed depressions—including dolines—across the Alburni karst massif, in southern Italy. A GIS-based, semi-automatic approach was employed, combining the sink-filling method (applied to a 5 m DEM) with the visual interpretation of various informative layers. This process produced a raster representing the location and depth of karst closed depressions. This raster was then used to automatically delineate endorheic areas using classic GIS tools. The resulting map reveals a thousand dolines and hundreds of adjacent endorheic areas. Endorheic areas form a complex mosaic across the massif, a feature that had been poorly emphasized in previous works. The main morphometric features of the dolines and endorheic areas were statistically analyzed and compared with the structural characteristics of the massif. The results of the proposed mapping approach provide valuable insights for groundwater management, karst area protection, recharge modeling, and tracer test planning. Full article

This study used Xinxin 2 (Juglans regia L. ‘Xinxin2’), a major cultivated walnut variety in Xinjiang, China, to clarify the response and adaptation mechanisms of the anatomical structures of walnut related to source–sink–flow under altered source–sink relationships. We anatomically observed the leaves, fruit stalks, and fruit of bearing branches by artificially adjusting the leaf-to-fruit ratio (LFR). The LFR substantially affected the leaf structure and thickness of the fruit-bearing branches obtained via girdled (p < 0.05). The results of the analysis of the leaf anatomy revealed that a low LFR impeded leaf growth and internal structural development while accelerating senescence, whereas a high LFR promoted leaf growth and delayed senescence. The same trend was observed for the phloem area (PA) of the fruit stalk with the increase in fruit load when the number of leaves on the fruit branch was the same. The maximum PA was reached when the number of fruits was high (except for 4L:3F). This indicates that the micro-anatomical structure of the fruit stalk is more developed under the treatment of a higher number of pinnate compound leaves and fruit level of LFRs. The cells of the 1L:3F and 2L:3F were considerably smaller in the green peel and kernel of the fruit on the branches obtained via girdled than those of 5L:1F plants (p < 0.05). No significant difference was found in the number of cells per unit area or the cross-sectional area of cells in the pericarp and kernel of the fruit under LFRs (p > 0.05); however, a large difference was noted in the microanatomical structure of the pericarp and kernel of fruit. Changes in the structural adaptation characteristics of walnut leaves (source), fruit stalk (flow), and fruit (sink) are related to source–sink regulation. A change in the LFR affects the carbohydrate synthesis in the leaves (source), transport in fruit stalks (flow), and the carbohydrate reception in fruits (sink). Full article

Steel cargo vessel sinking accidents (SCVSA) threaten maritime safety and disrupt global steel supply chains. This study integrates interpretive structural modeling (ISM) and fuzzy Bayesian networks (FBN) to evaluate SCVSA risks across the incident lifecycle. ISM identifies hierarchical relationships among multifaceted risk factors. FBN assesses lifecycle risks using fuzzy scoring, modular nodes, and a hierarchical structure, with muti-source data drawn from accident reports, expert opinions, and research studies. Experts estimate probabilities based on observations and causal scenarios involving steel cargo vessels at Shanghai Port. The ISM–FBN framework visualizes hierarchical risk factors and incorporates uncertainty in the data and causal relationships through fuzzy scoring, structural updates, and probability learning. This approach provides a robust and adaptable tool for assessing SCVSA risks, advancing maritime risk assessment methodologies. Key findings identify advanced vessel age, severe weather and sea conditions, and inadequate regulatory oversight as primary root causes. Poor cargo loading and stowage practices are direct contributors. Intermediate risk factors from deeper to surface layers flow from shipping companies to crew and further to vessel and environmental conditions. Multi-stage risk factors include inadequate emergency responses and improper cargo securing. To mitigate these risks, actionable insights are provided, including fleet modernization, enhanced regulatory compliance, crew training, and improved emergency preparedness. Full article

The regulatory mechanisms underlying the ‘source–sink’ relationship in Tartary buckwheat remain largely unexplored. This study selected an early-maturing, high-yield variety, ‘Zhukuzao1’ (ZKZ1), to delve into the ‘source–sink’ relationship and the regulatory mechanisms of phosphorus utilization. Compared with Jinqiao2 (JQ2), ZKZ1 matured approximately 10 days earlier, with significantly reduced chlorophyll content, net photosynthetic rate, and down-regulated PSI-III and GBSSI, indicating a reduced ‘source’. However, ZKZ1 maintained soluble sugar levels in upper leaves and increased sugar transport to seeds, promoting plant growth and yield formation. Under varying phosphorus conditions, ZKZ1 exhibited significantly higher total phosphorus content in lower (3.9~4.5-fold) and upper (1.4~1.6-fold) leaves of seedlings, along with increased phosphorus transport to upper leaves and seeds, and up-regulated PHO1 (2.4~3.0-fold), SPX3 (1.8~2.8-fold), PAP2 (2.8~7.7-fold), and 5PTase2 (1.4~3.5-fold) in leaves, indicating improved phosphorus absorption, transport, and remobilization. At maturity, ZKZ1 achieved yields comparable to JQ2, with superior quality traits, including significantly increased contents of protein (glutenin, prolamin, and globulin) and flavonoids under normal phosphorus conditions. Notably, the efficient phosphorus-regulated sugar metabolism in ZKZ1 maintains yield via enhanced ‘flow’ despite photosynthesis decrease. This study highlights the potential of optimizing the ‘source–sink’ relationship and phosphorus utilization in early-maturing, high-yield Tartary buckwheat breeding. Full article

Understanding the salinity transport process around the sediment–water interface is important for water resources management in the upper reach of an estuary. In this study, we developed a baroclinic fluid dynamic model for investigating the flow and salt transport characteristics within the sediment–water interface under tidal forcing. The validation showed robust model performance on the salinity transport within the sediment–water interface. The results revealed that the turbulent kinetic energy, dissipation rate, and kinetic energy production rate exhibited periodic variations within the seabed boundary layer. The thickness of the viscous sublayer and the mean flow showed an inverse relationship. Water and salinity exchange within the sediment–water interface occurred predominantly via turbulent diffusion, with extreme turbulent kinetic energy production rates appearing during the tidal reversal, flood, and ebb stages. The sediment acted as a source of salinity release during ebb tides and a sink for salinity absorption during flood tides. As the sediment depth increased, fluctuations in salinity were weakened. These results clearly illustrated that the sediment layer is important in modulating the salinity transport in the upper reach of an estuary. However, such an important process was usually excluded by previous studies. The model developed in this study can be used as a sediment–water interface module that, coupled with other hydrodynamic models, can evaluate the contributions of the sediment layer to the salinity exchange in coastal water. Full article

Understanding the flow processes and pattern optimization of ecosystem services (ESs) supply and demand is crucial for integrated regional ecological management. However, the understanding of the flow process of ESs at the 1 km grid scale is still limited, especially in areas dominated by mineral resource development. The landscape in these areas has undergone significant changes due to mining activities. It is urgent to construct a regional management model that integrates the flow of ecosystem services and mine restoration. This study developed a framework that links ecosystem service flows (ESFs) and ecological security patterns (ESP) based on multi-source ecological monitoring data, constructed an ES supply-demand flow network through the flow properties, and determined the sequence and optimization strategies for mine rehabilitation to achieve integrated regional management. The results show that, except for food production (FP), other services were in surplus overall, mostly in synergistic relationships, but the spatial distribution of their supply and demand was not coordinated. Surplus areas were located mainly in the eastern woodlands, and deficit areas were located in the northwestern production agglomeration centers, suggesting that areas of supply-demand imbalance can be mitigated through ecological integration. Among these, water yield (WY) had a small number of sources and sinks and is limited in area range. Habitat quality (HQ) sources and sinks had the largest area coverage and the highest number. The distribution of ESF corridors, influenced by factors such as the number of sources and sinks, flow characteristics, and spatial resistance, varied significantly. HQ exhibited a more uniform distribution range, while WY had a longer average length of flow path. Overlaying ecological and mining factors, we identified ecological strategic spots, important supply areas, beneficiary areas, and mine priority restoration areas to further optimize the overall layout and rationally allocate the intrinsic structure of the patches based on ES supply and demand. Full article

The flow characteristics of homogeneous gases in complex systems are an important issue in many areas, including underground mines. The flow in mine excavations and ventilation systems is described by known mathematical relationships that could be applied to various cases. In this paper, a flow in a duct with a local sink of mass and momentum for multiple variants of cooperation of a mechanical fan was analyzed. The relationships for the total and static pressure of air in the duct were derived. In the next stage, a calculation example of how the mass flow rate of air, and the total and static pressure of the flowing air will change in the tested sections for the duct with and without a sink, is presented. The derived formulas and calculated values for the considered calculation case allow the verification of the obtained relationships at the measurement station. Analyzing the results of the examples presented in the article, it can be concluded that the total and static pressure at the sink point differ depending on the equation of motion used. In the case of the classic equation, the value of total pressure is lower than the value calculated from the new equation of motion, and the difference between them is about 20 Pa. In the case of static pressure, this difference is about 46 Pa. Qualitative differences in the static pressure distribution at the release location were also demonstrated. Depending on the applied approach, positive or negative changes in the static pressure are noticed. The presented form of the equation of motion made it possible to determine the flow characteristics in the duct with a point mass and momentum sink in the case of the operation with and without a fan. Full article

In this study, the heat transfer model of a radiation–conduction–convection coupled lithium-ion battery pack is established through theoretical analysis. The temperature distribution and flow field distribution inside the battery pack are obtained by simulation using ANSYS Fluent software 2022 R1, and the reasonableness of the simulation model is verified with an experiment. This study also analyzes in detail the improvement effect of adding heat dissipation ribs, applying heat dissipation coatings, and adjusting the fan speed on the heat dissipation performance of the system. Under the same heat sink rib height conditions, the relationship between its thickness and total heat dissipation and thermal efficiency is studied in depth, and the temperature distribution of the cell under different rib thicknesses is obtained. At the same time, the emissivity of the heat sink coating under different coating thicknesses was measured by infrared thermography, and the relevant design values were determined through simulation experiments. Finally, based on the experimental test results of fan performance, a corresponding control strategy is proposed to construct an efficient and high-performance multiple-input multiple-output (MIMO) battery thermal management system. The experimental results show that optimizing the structure of the forced air cooling system through the above measures can ensure that the Li-ion battery operates within the efficient operating temperature range, thus extending its cycle life, improving its stability, and reducing the risk of thermal runaway. Meanwhile, the problem of excessive temperature difference between different modules is improved, and the output capacity of the energy storage system is increased. Full article

Group-activity scene graph (GASG) generation is a challenging task in computer vision, aiming to anticipate and describe relationships between subjects and objects in video sequences. Traditional video scene graph generation (VidSGG) methods focus on retrospective analysis, limiting their predictive capabilities. To enrich the scene-understanding capabilities, we introduced a GASG dataset extending the JRDB dataset with nuanced annotations involving appearance, interaction, position, relationship, and situation attributes. This work also introduces an innovative approach, a Hierarchical Attention–Flow (HAtt-Flow) mechanism, rooted in flow network theory to enhance GASG performance. Flow–attention incorporates flow conservation principles, fostering competition for sources and allocation for sinks, effectively preventing the generation of trivial attention. Our proposed approach offers a unique perspective on attention mechanisms, where conventional “values” and “keys” are transformed into sources and sinks, respectively, creating a novel framework for attention-based models. Through extensive experiments, we demonstrate the effectiveness of our Hatt-Flow model and the superiority of our proposed flow–attention mechanism. This work represents a significant advancement in predictive video scene understanding, providing valuable insights and techniques for applications that require real-time relationship prediction in video data. Full article

Source–sink zones refer to aggregated adjacent origins/destinations with homogeneous trip flow characteristics. Current relevant studies mostly detect source–sink zones based on outflow/inflow volumes without considering trip routes. Nevertheless, trip routes detail individuals’ journeys on road networks and give rise to relationships among human activities, road network structures, and land-use types. Therefore, this study developed a novel approach to delineate source–sink zones based on trip route aggregation on road networks. We first represented original trajectories using road segment sequences and applied the Latent Dirichlet Allocation (LDA) model to associate trajectories with route semantics. We then ran a hierarchical clustering operation to aggregate trajectories with similar route semantics. Finally, we adopted an adaptive multi-variable agglomeration strategy to associate the trajectory clusters with each traffic analysis zone to delineating source and sink zones, with a trajectory topic entropy defined as an indicator to analyze the dynamic impact between the road network and source–sink zones. We used taxi trajectories in Xiamen, China, to verify the effectiveness of the proposed method. Full article

This study aimed to investigate the influence of Al₂O₃ nanoparticle concentration and flow rate on the convective heat transfer coefficient in a heat sink. A testing apparatus was constructed to examine a microchannel heat sink coupled with an Al₂O₃ nanoparticle fluid. Temperature sensors were strategically placed at the microchannel heat sink’s entrance (T-in) and exit (T-out). Furthermore, a heating element (T-heater) was utilized to monitor the temperature of the nanoparticle fluid. This experimental setup allowed for precise temperature measurements in the system. Aluminum oxide (Al₂O₃) nanoparticles were thoroughly dispersed in water for 15 min using a magnetic stirrer, resulting in a uniform mixture with concentrations ranging from 0.2% to 1%. The experiments involved altering the flow rates within the range of 0.2 to 1.4 L per minute, enabling the monitoring of temperature changes (T). The heat transfer coefficient positively correlated with escalating concentrations of Al₂O₃ particles. Incorporating nanoparticles up to a concentration of 1% significantly enhanced the heat transfer coefficient by 17.29%. Additionally, a direct relationship was observed between the heat transfer coefficient and the increase in the flow rate of the Al₂O₃/water nanofluid. Specifically, when the flow rate was increased from 0.2 to 1.4 lpm, a significant enhancement in the heat transfer coefficient of 29.95% was achieved. Full article

High salt levels in soil can severely limit plant development and diminish the positive effect of plant-growth-promoting rhizobacteria (PGPR). However, extracts of organisms adapted to high salinity, such as Opuntia ficus-indica (OFI) and Enteromorpha intestinalis (EI), can restore the growth of PGPR. Therefore, we used OFI or EI extracts and their combination with the PGPR Achromobacter xylosoxidans BOA4 to evaluate salt stress relief in tomato (Solanum lycopersicum). The experimental setup consisted of a plant pot trial under greenhouse conditions with 12 treatments: control, irrigation with OFI extract; EI extract; BOA4-inoculated plus OFI extract and BOA4-inoculated plus EI extract under no salinity or salinity conditions (150 mM NaCl). The percentage of germination, and plant’s fresh and dry weight were registered 30 and 46 days after sowing. At 46 days, the ratio between proline and glutamic acid concentration (PR/GA) was determined, expecting high PR/GA ratios in plants more responsive to salt stress since proline is an osmolyte mainly synthesized from glutamate. The results showed that 52% of the control seeds under salt stress germinated, a figure that was increased to 92% in OFI-treated seeds. Tomato plants were shown to be very sensitive to salt stress since the dry weight was ca. one fourth that of the plants grown without salinity. However, EI or BOA4 plus EI stimulated plant biomass by ca. 3 times compared to the control with salt, restoring plant biomass to values comparable to those of control plants grown without salinity. The joint treatments with BOA4 and EI or OFI caused distinct PR/GA levels in plant tissues. An inverse relationship between the sum of relative shoot proline and glutamic acid contents and shoot biomass accumulation was observed, namely in treatments accumulating more biomass under no salinity and salinity conditions. This indicates that the proline/glutamate pathway represents a carbon sink that is needed to fight stress and is competing with the carbon flow used for growth. Full article