Plume Model Research Articles

Experimental Study on Evaporation and Ignition Behavior of RP-3 Fuel with Different Leakage Volumes on Hot Surface

ABSTRACT Fire accidents caused by fuel leakage to hot surfaces are of significant concern in the aerospace domain due to their potential for severe consequences. This paper investigates the evaporation and ignition characteristics of fuel leakage to a hot surface through a series of experiments with different volumes of RP-3 droplets. The evolution patterns of evaporation lifetime, ignition position, and ignition delay time are examined. The results show that within the surface temperature range of 500–700°C, the fuel droplets of all volumes almost immediately reach the film boiling state upon contact with the hot surface. The droplets move erratically across the surface, changing shape from irregular to elliptical and finally to spherical. The evaporation lifetime decreases with increasing hot surface temperature. The occurrence of ignition is stochastic, and the ignition probability rises with the hot surface temperature, while the minimum ignition temperature decreases with the increase of fuel volume. The movement of the fuel droplets in the film boiling state leads to the irregularity of the ignition position. Additionally, the ignition delay time decreases with an increase in the temperature of the hot surface. The relationship between ignition delay time and surface temperature in the film boiling state is discussed in the context of the vapor plume model and boiling heat transfer analysis.

Unveiling heavy metal(loid) contamination and migration at an abandoned smelting site: Integrated geophysical and hydrological analyse

The heavy metal contamination at abandoned smelting sites is receiving increasing attention. This study focuses on an abandoned lead–zinc smelting site and uses several methods (such as soil sampling, geophysical exploration, and groundwater monitoring) to systematically investigate the contamination characteristics, distribution patterns, and migration mechanisms of heavy metal(loid) in soil and groundwater. A geological structure model of the study area was established through drilling data and geophysical techniques (Ground penetrating radar (GPR) and Electrical resistivity tomography (ERT)), revealing the relationships among soil resistivity, electromagnetic wave reflection characteristics, and geological structure. This study revealed that heavy metal contamination in soil was concentrated mainly northwest of the site and was closely related to historical smelting activities. The presence of heavy metal(loid)s in groundwater had a complex correlation with soil physicochemical properties and environmental elements, and its distribution was influenced by both hydrogeological conditions and soil properties. This study also investigated the effects of the soil water content (SWC) and soil hydraulic conductivity (Ks) on heavy metal(loid)s migration and reported that high SWC and Ks contribute to the dissolution and migration of heavy metals. In addition, a 3D visualization model of heavy metal contamination plumes was established via Voxler software. This model intuitively demonstrated the migration and diffusion of heavy metal(loid)s in the underground environment, offering a novel perspective on their subsurface behavior. The research results provide important information for understanding the migration of heavy metal(loid)s in soil-groundwater systems.

Estimation and research of the temperature field models of large space spherical mesh shell structures under localized fire

This paper firstly investigated fire dynamics characteristics and the temperature field distributions of large space spherical mesh shell (SMS) structures under localized fire in FDS, and divided the temperature fields into plume region, smoke accumulation region and ceiling jet region. Based on the classical axisymmetric plume model, the predictive models for the steady-state and transient temperature fields in different fire regions for large space SMS structures were proposed in this paper. Thereafter, the proposed temperature models were compared with the simulated results and experimental test results by other scholars, and they were in good agreement. In order to further discover the realistic fire development progress and temperature distribution of large space fire, and validate the proposed temperature field models, this paper designed and conducted three full-scale large space fire tests (Test-1 ∼ Test-3) with different fire source powers in a large space building. Results showed that temperature fields of large space fires could be consisted of near-fire region (Flame region) and far-fire region (Plume region and Ceiling jet region). The steady-state fire source powers were tested for 443 kW, 886 kW, 1090 kW for Test-1, Test-2 and Test-3, respectively, while their maximum temperatures of the roof reached 75 °C, 105 °C and 120 °C. Based on McCaffrey plume model, we further proposed the transient temperature model in flame region for large space structures, and its accuracy was verified by the test results. Moreover, the proposed steady-state and transient temperature fields for large space SMS structures were compared with the tested temperature field data, and the tested and predicted temperature curves were generally in good agreement in plume and ceiling jet regions. Finally, the test results aimed to provide a scientific basis and reference for the fire safety and structural fire-resistant design of large space buildings.

Enhancing Global Simulation of Smoke Injection Height for Intense Pyro‐Convection Through Coupling an Improved One‐Dimensional Plume Rise Model in CAM‐chem

AbstractThe impact of wildfire smoke is largely determined by the height where they are injected into the atmosphere. Current plume rise models tend to underestimate the high smoke injection heights because the previous models and configurations were mainly constrained and validated by the plume height observation from Multi‐angle Imaging SpectroRadiometer (MISR), of which most cases inject low within the planetary boundary layer (PBL). Here we retrieve smoke injection heights from intense pyro‐convections based on pyrocumulonimbus satellite images in PYROCAST data set alongside meteorological reanalysis. It largely augments the MISR data set with smoke injection heights up to the upper troposphere and lower stratosphere (UTLS). Constrained by both MISR and PYROCAST, we show that a scaling down of factor 0.2 to the entrainment efficiency parameterized in the one‐dimensional plume‐rise model (1‐D PRM, Freitas et al. (2010, https://doi.org/10.5194/acp‐10‐585‐2010)) significantly improves the model performance for high injection cases without compromising the accuracy of low injection cases. We also found that the fire intensity input can be obtained through a simplified dependence on the biome and biomass burning emission flux. While being unable to represent high cases before, the improved 1‐D PRM model predicts similarly well in injection heights both low near the PBL height and high into the UTLS. The improved 1‐D PRM is then coupled into Community Atmosphere Model with Chemistry (CAM‐chem). The coupled CAM‐chem‐PRM, when predicting injection heights in tests imitating real BB emission, exhibited consistent predictive capabilities with the standalone 1‐D PRM while saw a mere 15% increase of computation time.

Diffusion behavior and environmental impact of odorants and TVOCs detected in a wastewater treatment plant for collaborative leachate treatment in Northwest China

Wastewater treatment plants (WWTPs) are major sources of volatile gaseous compounds, especially in mixed-source systems such as domestic wastewater and landfill leachate. This study aimed to investigate the emission behavior and environmental impact of gaseous substances, such as hydrogen sulfide (H2S), ammonia (NH3), carbon sulfide (CS2), and phosphine (PH3), at a WWTP in Northwest China. Odorants were detected in the air surrounding the grid room (XGS), biochemical treatment tank (SHC), secondary sedimentation tank (ECC), and sludge dewatering room (NTS). For comparison, the upwind boundary (O-SF) and downwind boundaries (O-XF) monitoring points were used, with odor concentrations ranging from 3.95 to 725.27 odor units. The concentration ranges of the odorant substances were 5.27–88.69, 5.61–71.96, 5.70–32.63, and 0.12–5.87 mg/m3 for H2S, NH3, CS2, and PH3, respectively. Meteorological factors such as temperature, relative humidity, and wind speed and direction substantially influence odorant emissions. The concentrations of various odorants and volatile organic compounds (VOCs) detected at the O-XF monitoring point were higher than those detected at the O-SF monitoring point, indicating that the wind intensified their diffusion toward the downwind plant boundary. The average odor intensities of odorant substances emitted from wastewater or sludge treatment equipment were 3.37, 5.09, 4.42, 2.00, and 3.82 for total VOCs, H2S, NH3, CS2, and PH3, respectively. Among them four, with downwind diffusion, only H2S presented olfactory and chronic toxicity risks based on Gaussian plume model calculations. The hazard index ranking across monitoring sites was XGS > NTS > SHC > ECC > O-XF > O-SF. These findings emphasize the urgent need for effective measures to control and mitigate gaseous pollutants emitted by collaborative WWTPS, thereby protecting environmental quality and public health.

Hall thruster model improvement by multidisciplinary uncertainty quantification

We study the analysis and refinement of a predictive engineering model for enabling rapid prediction of Hall thruster system performance across a range of operating and environmental conditions and epistemic and aleatoric uncertainties. In particular, we describe an approach by which experimentally-observed facility effects are assimilated into the model, with a specific focus on facility background pressure. We propose a multifidelity, multidisciplinary approach for Bayesian calibration of an integrated system comprised of a set of component models. Furthermore, we perform uncertainty quantification over the calibrated model to assess the effects of epistemic and aleatoric uncertainty. This approach is realized on a coupled system of cathode, thruster, and plume models that predicts global quantities of interest (QoIs) such as thrust, efficiency, and discharge current as a function of operating conditions such as discharge voltage, mass flow rate, and background chamber pressure. As part of the calibration and prediction, we propose a number of metrics for assessing predictive model quality. Based on these metrics, we found that our proposed framework produces a calibrated model that is more accurate, sometimes by an order of magnitude, than engineering models using nominal parameters found in the literature. We also found for many QoIs that the remaining uncertainty was not sufficient to account for discrepancy with experimental data, and that existing models for facility effects do not sufficiently capture experimental trends. Finally, we confirmed through a global sensitivity analysis the prior intuition that anomalous transport dominates model uncertainty, and we conclude by suggesting several paths for future model improvement. We envision that the proposed metrics and procedures can guide the refinement of future model development activities.

Long-term observations of the turbid outflow plume from the Russian River, California

Understanding the mechanisms that spread freshwater away from small river systems and form turbid, low-salinity coastal plumes is crucial for assessing water quality in coastal waters. We present an analysis of 15 years (January 2004 to December 2018) of daily MODIS Aqua satellite data and in situ instrument data on the turbid freshwater plume that forms off the Russian River (California, USA), a prototypical Mediterranean-climate, small mountainous river system (SMRS). We present per-pixel statistical metrics and regression analyses to identify and quantify the controls on the extent and configuration of the plume exerted by river discharge, waves, winds, and tides. While freshwater outflow exhibits a persistent signal in nearshore waters, a large-scale plume only extends offshore into coastal waters during high river flow, when plume turbidity can be detected more than 10 km offshore from the river mouth. Our results show times when wave radiation stress exceeds outflow inertia, confining the plume within the surf zone and leading to an absence of detectable plume turbidity in coastal waters. Although tidal currents significantly influence the plume near the inlet, wind forcing is the primary control on plume shape and extent in coastal waters, deflecting the turbid outflow more than 30 km upcoast or downcoast of the river mouth with respective wind directions. Coriolis forcing is also significant and observed most clearly during periods of high river discharge and low wind forcing. In addition to introducing novel remote sensing methodology for SMRS plume analyses, these findings highlight the complex interplay of forcing related to tides, river discharge, winds, and waves in shaping the behavior of SMRS plumes. New insights include the impact of tides on larger discharges, the role of Coriolis forcing in SMRS plumes, and the effect of cross-shore winds on plume compression. Further, by considering the Russian River as a model for SMRS, this study can be used to ground-truth existing numerical models of small river plumes and to contribute to understanding critical for managing coastal water quality and nearshore ecosystems.

Computational fluid dynamics simulation of ammonia leakage scenarios during ship-to-ship bunkering

Ammonia is emerging as a potential marine fuel, yet its toxicity and risk of accidental leaks pose significant safety challenges compared to other alternatives. This study focuses on the critical ship-to-ship bunkering process using Computational Fluid Dynamics (CFD) simulations to analyse diverse ammonia leakage scenarios considering various leak orientations relative to the wind and the ships. The numerical setup was initially validated against controlled experiments, demonstrating satisfactory agreement. Results indicate that atmospheric ammonia dispersion is significantly influenced by obstacles like the superstructure and hull in the near field, with diminishing effect in the far field. Conventional Gaussian plume models are inadequate within the first few hundred metres from the release source due to the complex near-field flow patterns and increased turbulence generated by the wakes of the hull and superstructure. These findings underscore the necessity for improved ship-scale dispersion models to accurately evaluate the impact of obstacles on ammonia dispersion. The consequence analysis reveals that upward leaks create larger risk zones with potential for irreversible health effects, while horizontal leaks may expose personnel to life-threatening concentrations. Vertical leaks in crosswind configurations generate lethal zones covering tens of metres on deck. These results highlight the importance of considering the exact location of the transfer hose relative to the ship and all potential wind orientations in risk assessments. Given the extensive range of potential dispersion patterns and the inadequacy of conventional Gaussian dispersion models in this context, we strongly recommend vessel-specific CFD simulations before certifying ammonia bunkering operations as safe. This approach is crucial for accurate risk assessment at the ship scale, where complex geometries and multi-directional flows invalidate the assumptions of traditional point-source, uni-directional dispersion models.

Comparing Large-Eddy Simulation and Gaussian Plume Model to Sensor Measurements of an Urban Smoke Plume

The fast prediction of the extent and impact of accidental air pollution releases is important to enable a quick and informed response, especially in cities. Despite this importance, only a small number of case studies are available studying the dispersion of air pollutants from fires in a short distance (O(1 km)) in urban areas. While monitoring pollution levels in Southampton, UK, using low-cost sensors, a fire broke out from an outbuilding containing roughly 3000 reels of highly flammable cine nitrate film and movie equipment, which resulted in high values of PM2.5 being measured by the sensors approximately 1500 m downstream of the fire site. This provided a unique opportunity to evaluate urban air pollution dispersion models using observed data for PM2.5 and the meteorological conditions. Two numerical approaches were used to simulate the plume from the transient fire: a high-fidelity computational fluid dynamics model with large-eddy simulation (LES) embedded in the open-source package OpenFOAM, and a lower-fidelity Gaussian plume model implemented in a commercial software package: the Atmospheric Dispersion Modeling System (ADMS). Both numerical models were able to quantitatively reproduce consistent spatial and temporal profiles of the PM2.5 concentration at approximately 1500 m downstream of the fire site. Considering the unavoidable large uncertainties, a comparison between the sensor measurements and the numerical predictions was carried out, leading to an approximate estimation of the emission rate, temperature, and the start and duration of the fire. The estimation of the fire start time was consistent with the local authority report. The LES data showed that the fire lasted for at least 80 min at an emission rate of 50 g/s of PM2.5. The emission was significantly greater than a ‘normal’ house fire reported in the literature, suggesting the crucial importance of the emission estimation and monitoring of PM2.5 concentration in such incidents. Finally, we discuss the advantages and limitations of the two numerical approaches, aiming to suggest the selection of fast-response numerical models at various compromised levels of accuracy, efficiency and cost.

Modelling the maximum ceiling temperature with bifurcated plume in tunnel fires

Evaluation of the temperature profile induced by tunnel fire is of great significance for fire detection and structural damage assessment. In this work, a special plume model, namely, the “plume bifurcation” is introduced, and its impact on the temperature distribution is analysed theoretically. Full-scale tunnel fire experiments and numerical simulations are conducted to investigate the plume evolution under various heat release rates and ventilation conditions. Results show that the plume will sperate into two sub-streams under strong ventilation condition, resulting in the multi-dimensional plume movement pattern when rising. The sub-plume impingement point location, quantified by the longitudinal vertical deflection angle θv and horizontal bifurcation angle θh, is correlated with the fire heat release rate and ventilation condition. The plume bifurcation angle is 0 when the dimensionless ventilation velocity V′≤0.33, marking a single-stream plume; and rapidly increase and then slowly decrease with V′ when V′>0.33, representing the sudden occurrence and decay trend of plume bifurcation with the ventilation velocity. Finally, a novel bifurcated plume-based model to estimate the maximum ceiling temperature is proposed. This study reveals the role of multi-dimensional smoke movement in reshaping the temperature field, providing new perspectives for a deeper understanding of the smoke transport behaviour in longitudinally ventilated tunnel fires.

Anatomy of the Emeishan Mantle Plume Head: Insights From New Geochronologic, Geochemical, and Geologic Data

AbstractThe link between mantle plumes and the formation of large igneous provinces (LIPs) is well established although the anatomy of these remains equivocal. Recent experimental studies and geophysical data suggest that the mantle plume head is more likely to be irregular and asymmetric, rather than an axisymmetric flattened disk. The Emeishan large igneous province (ELIP) provides a unique opportunity to test this hypothesis. According to robust petrographic, geochronologic, and geochemical evidence from the late Permian basalts in the Sichuan Basin, and in conjunction with a comprehensive compilation of geologic maps and published geochemical data from the ELIP, we identified several giant radial “fingering” structures. Based on the shallow mantle source from the center to margin in the ELIP and relief of the lithosphere‐asthenosphere boundary, we propose a new mantle plume model to explain the evolution of the Emeishan plume periphery, where narrow finger‐like protrusions and plumelets developed outwards from the main body of the plume to the edges of the flattened plume head. Dragged fingers might have been torn apart into some plumelets, which dispersed and were trapped beneath the thinnest lithosphere relief, and eventually erupted to form small‐scale flood basalt in the Outer Zone of the ELIP.

Weak long‐range diffusion

AbstractWe study the spreading solutions of the nonlinear diffusion equation when the far‐field diffusivity is small. The method of strained coordinates is used to construct a uniform asymptotic correction to the similarity solution of the unperturbed problem. The equation provides a possible analogue to similar models of fluid jets and plumes.

The Gaussian Plume Model Equation for Atmospheric Dispersion Corrected for Multiple Reflections at Parallel Boundaries: A Mathematical Rewriting of the Model and Some Numerical Testing

The well-known Gaussian plume model has proven to be very useful in simulating the atmospheric dispersion of air pollutants (both gaseous and particulates). Nevertheless, the nature of the model presents problems in the actual computation of concentrations when the plume is confined between two parallel boundaries due to the occurrence of multiple reflections. The ground and temperature inversion lid (especially, when the inversion layer is at low levels in the atmosphere) with a chimney stack releasing the effluent below the latter, is one contextual example of horizontal parallel reflecting boundaries. A second example is buildings confining a roadway on either side, with motor vehicles emitting pollution within the street canyon (or urban notch). In such cases, multiple reflections should be accounted for, otherwise the model underpredicts the resulting concentration. This paper presents a mathematical rewriting of the Gaussian plume model equation corrected for multiple reflections when the pollution source is confined between parallel boundaries. The obtained result is most appropriate when the parallel boundaries are rigid, and near-complete reflection is achieved, e.g., street canyon environment (second quoted example). It is worth noting that the relevant mathematical derivations and definitions are all included in the paper to facilitate reading and to ensure comprehensiveness in the presentation. Additionally, the outcome of some preliminary numerical testing is presented. The latter indicates that the new formulation is mathematically stable and yields interesting results. Further numerical investigation and experimental evaluation are merited.

Yampi Peninsula felsic Hart Dolerite: re-evaluating the Nellie Tonalite using evidence from whole rock, petrography and geochronology

The Nellie Tonalite forms a discontinuous 20 km elongate northwest-trending felsic intrusion at the far-western end of the Western Zone of the Lamboo Province, in the Wunaamin Miliwundi Orogen, Western Australia. This intrusion is poorly understood with previous interpretations assigning it to the ca 1860 Ma Paperbark Supersuite. We present the first geochronological results for the Nellie Tonalite, which have a weighted mean laser ablation, inductively coupled plasma, mass spectrometry (LA-ICP-MS) U–Pb zircon age of 1794 ± 4 Ma. This date is coincident with the age for felsic granophyres of the Hart Dolerite, which have previously been described from the Kimberley Basin overlying the Halls Creek Orogen and central parts of the Wunaamin Miliwundi Orogen. Other similarities of the Nellie Tonalite with the felsic Hart Dolerite are micrographic and granophyric intergrowths of quartz and K-feldspar, and a distinct geochemical depletion of V. This V depletion is interpreted to be the result of closed-system, in situ fractional crystallisation of titanomagnetite from a basaltic composition. The fractional residue from this process can be found at several locations across the Halls Creek Orogen and Wunaamin Miliwundi Orogen and at Speewah Dome in the east Kimberley where magnetite gabbros within the Hart Dolerite also host a large Ti–V mineral resource. It is proposed that the Nellie Tonalite is a western correlate of the felsic Hart Dolerite. This demonstrates that the magmatic processes required for Speewah-style Ti–V mineralisation are extensive across the entire Lamboo Province. Additionally, the scale, constancy of the composition, texture and age of the felsic Hart Dolerite encompassing the entire inland margin of the Kimberley Region, and the rapid emplacement time of <3 m.y., support the interpretation of a mantle plume model for the emplacement of the Hart Dolerite.

Numerical simulation and analysis of initial plume discharge of deep-sea mining

Deep-sea mining involved environmental issues that urgently need to be addressed. The fine particle plume released from the surface vessel during deep-sea mining can impact the sea ecosystem, so investigating the characteristics of initial plume discharge is of significant importance for deep-sea mining systems. By numerical simulating the plume discharge process based on the two-fluid Eulerian model, this study explores the influence of initial discharge velocity, initial particle concentration, pipe diameter, and particle size on the surface plume discharge. The evolution mechanism of the plume is investigated through classic plume models involving the interaction of volume flux, momentum flux, buoyancy flux and the numerical simulation results exhibit a consistent trend with theoretical expectations. The results indicate that fine particle discharge velocity, discharge concentration, and pipe diameter are key influencing factors in plume evolution. The discharge velocity and pipe diameter primarily affect the evolution morphology of the plume through momentum flux and buoyancy flux. The discharge concentration mainly affects the plume's evolution through buoyancy flux.

Modeling the Enceladus dust plume based on in situ measurements performed with the Cassini Cosmic Dust Analyzer

We analyzed data recorded by the Cosmic Dust Analyzer on board the Cassini spacecraft during Enceladus dust plume traversals. Our focus was on profiles of relative abundances of grains of different compositional types derived from mass spectra recorded with the Dust Analyzer subsystem during the Cassini flybys E5 and E17. The E5 profile, corresponding to a steep and fast traversal of the plume, has already been analyzed. In this paper, we included a second profile from the E17 flyby involving a nearly horizontal traversal of the south polar terrain at a significantly lower velocity. Additionally, we incorporated dust detection rates from the High Rate Detector subsystem during flybys E7 and E21. We derived grain size ranges in the different observational data sets and used these data to constrain parameters for a new dust plume model. This model was constructed using a mathematical description of dust ejection implemented in the software package DUDI. Further constraints included published velocities of gas ejection, positions of gas and dust jets, and the mass production rate of the plume. Our model employs two different types of sources: diffuse sources of dust ejected with a lower velocity and jets with a faster and more colimated emission. From our model, we derived dust mass production rates for different compositional grain types, amounting to at least 28 kg/s. Previously, salt-rich dust was believed to dominate the plume mass based on E5 data alone. The E17 profile shows a dominance of organic-enriched grains over the south polar terrain, a region not well constrained by E5 data. By including both E5 and E17 profiles, we find the salt-rich dust contribution to be at most 1&lt;!PCT!&gt; by mass. This revision also results from an improved understanding of grain masses of various compositional types that implies smaller sizes for salt-rich grains. Our new model can predict grain numbers and masses for future mission detectors during plume traversals.

A comprehensive dosimetry analysis of barakah nuclear power plant: Integrating gaseous and liquid radionuclide dispersion across multiple units

Monitoring radioactive releases during the normal operation of power plants is crucial to ensure compliance with safety limits set by regulatory bodies for environmental safety. In the case of the Barakah nuclear power plant in the UAE, comprehensive multiunit dispersion modelling and radiological safety analysis have been conducted. Utilizing the HotSpot Health Physics Code and GENII (Second-generation environmental dosimetry), assessments were made for both 37 gaseous and 51 liquid source terms generated by GALE. Release rates for source terms were determined using GALE based on APR 1400 specifications. HotSpot employed the Gaussian Plume model to simulate the dispersion of gaseous source terms up to 80 km surrounding the plant, calculating Total Effective Dose Equivalent (TEDE) and Committed Effective Dose Equivalent (CEDE) in rural and urban areas. Findings indicated that neither scenario exceeded the 1 mSv threshold for the general public nor the 20 mSv limit for operational workers. Notably, skin, thyroid, and surface bones exhibited the highest CEDE, primarily influenced by iodide radionuclides. GENII's Surface Water module modelled the effects of liquid source terms, accounting for various contamination and exposure pathways such as external exposure and ingestion across different age groups. The calculated doses remained well below FANR's annual limits, with negligible cancer incidences and fatalities predicted for one year of exposure.

Waveform modelling of hydroacoustic teleseismic earthquake records from autonomous Mermaid floats

SUMMARY We present a computational technique to model hydroacoustic waveforms from teleseismic earthquakes recorded by mid-column Mermaid floats deployed in the Pacific, taking into consideration bathymetric effects that modify seismo-acoustic conversions at the ocean bottom and acoustic wave propagation in the ocean layer, including reverberations. Our approach couples axisymmetric spectral-element simulations performed for moment-tensor earthquakes in a 1-D solid Earth to a 2-D Cartesian fluid–solid coupled spectral-element simulation that captures the conversion from displacement to acoustic pressure at an ocean-bottom interface with accurate bathymetry. We applied our workflow to 1129 seismograms for 682 earthquakes from 16 Mermaids (short for Mobile Earthquake Recording in Marine Areas by Independent Divers) owned by Princeton University that were deployed in the Southern Pacific as part of the South Pacific Plume Imaging and Modeling (SPPIM) project. We compare the modelled synthetic waveforms to the observed records in individually selected frequency bands aimed at reducing local noise levels while maximizing earthquake-generated signal content. The modelled waveforms match the observations very well, with a median correlation coefficient of 0.72, and some as high as 0.95. We compare our correlation-based traveltime measurements to measurements made on the same data set determined by automated arrival-time picking and ray- traced traveltime predictions, with the aim of opening up the use of Mermaid records for global seismic tomography via full-waveform inversion.

Quantitative determination of SO2 flux from industrial chimney through machine vision with plume model verification

Accurate emission rate data are essential for assessing the environmental impact of industrial emissions and calibrating the effectiveness of desulphurization equipment. However, accurate calculation of SO2 emissions is difficult to realize due to the environmental conditions, the time-varying and spatial non-uniformity of pollution source emissions. In this paper, a Dual TV Plus machine vision algorithm is proposed, calculated and validated with the conventional Farneback optical flow algorithm in terms of industrial stack emission rates. In addition, the effect of turbulence on the inversion of SO2 emission under complex environmental conditions is evaluated by combining simulations and outdoor experiments. The results show that the Dual TV Plus algorithm performs better than the Farnebäck algorithm and the Dual TV-L1 algorithm, with 50% and 30% improvement in accuracy and 5% and 8% improvement in immunity to interference, respectively. This work is important for promoting the engineering applications of remote sensing instruments for environmental monitoring.

Genesis of the Neoarchean Algoma-type banded iron formation: constraints from Fe isotope and element geochemistry of the Qian’an iron deposit, eastern North China craton

The Neoarchean Qian’an BIF deposit in eastern Hebei, eastern North China Craton has attracted extensive attention of study in the last decades, but the genesis, e.g., Fe sources, metallogenic mechanism, as well as tectonic attributes of the BIFs remains highly disputed. Based on field investigations, microscopic observations and geochemical analysis, this study tries to unravel the source characteristics of ore-forming materials in the Qian’an deposit. The results show that the chemical compositions of the BIF ore samples are mainly composed of TFe2O3 and SiO2, with minor Al2O3 and TiO2. The total trace element contents of the samples are relatively low. The PAAS-normalized REE distribution patterns of the ores show LREE depletion and HREE enrichment, with robust positive anomalies of Eu, Y and La. These characteristics indicate that the BIFs are attributed to dominant chemical precipitation originated from paleo-ocean with obvious volcanic hydrothermal contributions and minor clastic input. Their positive to no Ce anomalies and positive δ56Femagnetite values unveil that the iron was precipitated at low oxygen fugacity. These results, in collaboration with evidence from previous lithological, structural geology, metamorphic P-T paths, geochemistry, geochronology and numerical modeling studies, support a mantle plume model to explain the complicated tectono-thermal processes, and the sources of BIFs in Eastern Hebei, eastern North China Craton.