Spreading Rate Research Articles

The Global Spectrum of Seafloor Morphology on Mid‐Ocean Ridge Flanks Related to Magma Supply

AbstractMagma supply likely exerts primary control on seafloor morphology of oceanic crust, but most studies have related morphology to spreading rate. Here we examine global patterns of morphology on mid‐ocean ridge (MOR) flanks in relation to magma supply derived from residual mantle Bouguer gravity anomaly (proxy for relative crustal thickness) and spreading rate. We use multibeam bathymetry to characterize morphology using both qualitative (descriptive) and quantitative approaches, and we compare results to both magma supply and spreading rate. Morphology becomes more isotropic and abyssal hills are more irregular and discontinuous as magma supply decreases, while roughness, area of steeper slopes, and anomalous fabric orientation increase. We interpret these changes to reflect changing magma distribution along‐axis, from large‐volume and spatially extensive to progressively reduced, increasingly localized, and more irregularly emplaced. Observed relations between crustal thickness and morphology imply that average thickness of purely magmatic crust in the Atlantic and parts of the Indian ridge system is significantly less than average seismically determined crust. Thus seismically defined crustal thickness in those regions likely includes significant non‐magmatic components such as serpentinized mantle. Excepting regions of extensive mantle exposure, most morphologic parameters that we examined are sensitive to estimated magma supply but not necessarily to spreading rate alone. We summarize our results in schematic models that relate morphologic variations to changes in magma supply and mantle serpentinization throughout the global MOR system. Finally, we note that combined qualitative and quantitative results of our study may be useful for developing automated morphologic classification schemes.

Impact of Kerguelen, Marion, and Reunion plumes on the ophiolitic obduction at the northern margin of Indian plate

Geochronological data compiled for 29 major ophiolitic occurrences from the northern margin of the Indian plate precisely coincide with the three major mantle plume interactions over Indian plate (viz., Kerguelen at 130–110 Ma, Marion at 90–84 Ma, and Reunion at 65–70 Ma). We analysed i) the geological juxtapositions of these ophiolitic belts, ii) seismic tomographic imaging of the slab breakoffs, iii) equivalent deflections in the marine magnetic anomalies (MMA), iv) stratigraphic records of the Cretaceous formations and v) the paleomagnetic inclination anomalies; and propose significant influence of plume-driven forces over the subduction and obduction processes in Himalayas. The impingement of Kerguelen plume strongly influenced the ∼ 2500 km long subduction of Neo-Tethys, leading to Indus-Tsangpo-Suture-Zone (ITSZ) ophiolites with their metamorphic soles. The impact of Marion plume further led to repeated tilting of the Indian plate reinvigorating Tethyan subduction at 90 ± 5 Ma. The Reunion event at ∼ 65 Ma, led to the mega-obduction along the Tethyan margin of the Indian subcontinent. The Kerguelen plume thus played a key role in initiating the intraoceanic subductions in equatorial Neo-Tethys, and the combined slab pull and plume induced rifting separated Greater India microcontinent from the northern margin of Indian subcontinent at ∼ 120 Ma. The impact of the Reunion plume resulted in the obduction of ITSZ ophiolites at the northern margin and the Pakistan ophiolites at the northwestern margin. The mantle plume impingements caused plate tilting and triggered the subduction/obduction that is well preserved by sharp inflexions in MMA and the spreading rates. We therefore infer that the three mantle plumes have a greater role in the subduction, obduction and tilting of the Indian plate throughout the Late Mesozoic.

Source variations in volatile contents of Bransfield Strait back-arc and Phoenix/West Scotia mid-ocean ridge lavas, northern Antarctic Peninsula

We present the first volatile contents (H2O, CO2, Cl, F, S) of young (< 6 Ma) submarine basaltic glasses from the Phoenix and West Scotia mid-ocean ridges and the Bransfield Strait back-arc of the South Shetland subduction zone in the Antarctic Peninsula.The volatile contents of the MORB glasses correspond well with those of published Pacific MORB and reflect covariations in source enrichment and extent of melting. Our results support the hypothesis that decreasing spreading rates at the Phoenix Ridge resulted in preferential melting of less abundant enriched MORB mantle, due to its greater fertility and higher volatile contents, relative to the more abundant depleted MORB mantle.The volatile contents of the Bransfield Strait back-arc glasses correlate with geochemical indicators of subduction processes and reveal an along-axis spatial distribution consistent with a toroidal inflow of sub-slab asthenosphere around the edges of the subducting plate into the mantle wedge. This inflow should be considered when assessing spatial and geochemical variability at subduction zones, particularly those with slab windows and tears.A small group of Bransfield Strait samples have volatile contents that do not correlate with geochemical signals of subduction influence. We speculate that these samples reflect flux melting of residual enriched mantle brought beneath the Bransfield Strait via corner flow following recent alkaline magmatism in the far eastern regions of the Antarctic Peninsula.Our new data on lavas from the W7 segment of the West Scotia Ridge reveal their source was significantly affected by subduction processes. Unexpectedly, these lavas have CO2-H2O pressures of vapor saturation that suggest they were collected in-situ and erupted relatively recently (∼6 Ma), at odds with previous interpretations of their origins. We suggest they originated from a subduction-modified mantle (lithosphere or asthenosphere) left behind by the eastward-migrating South Sandwich subduction zone sometime over the past ∼30 Myr. These lavas demonstrate the long-lasting effects of subduction processes on the upper mantle and their potential to influence melt compositions even in non-subduction environments today.We use the compositions of lavas from the Phoenix Ridge and Bransfield Strait to estimate mantle potential temperatures; our results agree well with global estimates for mid-ocean ridges and subduction zones, respectively.

Aerodynamic and Thermal Field Development of Cooled Transonic HP NGV

Abstract In this study we present detailed aerodynamic and thermal field measurements downstream of an annular cascade of fully-cooled nozzle guide vanes (NGVs). The experiments were conducted in the Engine Component Aerothermal (ECAT) facility at the University of Oxford, at engine-matched conditions of Reynolds number and Mach number, and high turbulence intensity. The experimental data are unusually high-fidelity and allow for detailed comparison with modern computational fluids dynamics (CFD) methods. We compare the experimental data to simulations of fully-featured geometry (resolved internal geometry and film cooling holes). We analyze distributions of whirl angle, kinetic energy loss, and non-dimensional temperature at three axial planes downstream of the NGVs. The aerodynamic and thermal wakes are also characterized in terms of their spreading and decay rates. The analysis is deepened with detailed comparison to a previous data-set for a different design of heavily-cooled NGV. The analysis is a useful reference point for assessing the accuracy of the current state-of-the-art numerical methods used in the engine design process.

Formation conditions of the young flat-slab in the wedge subduction zone

A wedge subduction can initiate after a ridge subduction and is characterized by the young and thin part of the plate subducting first. A series of 2D geodynamical models were built to investigate the factors in the development of a young flat-slab during the wedge subduction process after a ridge subduction. The factors include the convergence rate, the half spreading rate of the ridge, the initial subduction angle, and the thickness of the overriding plate. The results show that a flat-slab generally forms before the slab age reaches 40 Myr, except in special cases, for instance, when convergence rate≤1 cm/yr, the half spreading rate is low, or the initial subduction angle≥55°. The wedge subduction slab is prone to flatten because the young wedge subduction slab is naturally accompanied by buoyancy anomaly and has the potential to flatten at the relatively low convergence rate. There is no evidence as to whether a flat-slab exists south of Chile Triple Junction. According to the simulation results, the tomographic evidence, and the oceanic age distribution, it can be inferred that, from 46.5°S to ∼50°S, the wedge subduction is in the initiation stage and the formation of a flat-slap is impossible. Near 50–52°S, the slab possibly flattens when the initial subduction angle is 20–30°. From ∼52°S to ∼55°S, when the initial subduction angle is 20–40°, a flat subduction is likely to occur.

What Controls the Entrainment Rate of Dry Buoyant Thermals with Varying Initial Aspect Ratio?

Abstract This study uses theory and numerical simulations to analyze the nondimensional spreading rate α (change in radius with height) of buoyant thermals as they rise and entrain surrounding environmental fluid. A focus is on how α varies with initial thermal aspect ratio Ar, defined as height divided by width of the initial buoyancy perturbation. An analytic equation for thermal ascent rate wt that depends on α is derived from the thermal-volume-averaged momentum budget equation. The thermal top height when wt is maximum, defining a critical height zc, is inversely proportional to α. The height zc also corresponds to the thermal top height when buoyant fluid along the thermal’s vertical axis is fully replaced by entrained nonbuoyant environmental fluid rising from below the thermal. The time scale for this process is controlled by the vertical velocity of parcels rising upward through the thermal’s core. This parcel vertical velocity is approximated from Hill’s analytic spherical vortex, yielding an analytic inverse relation between α and Ar. Physically, this α–Ar relation is connected to changes in circulation as Ar is modified. Numerical simulations of thermals with Ar varied from 0.5 to 2 give α values close to the analytic theoretical relation, with a factor of ∼3 decrease in α as Ar is increased from 0.5 to 2. The theory also explains why α of initially spherical thermals from past laboratory and modeling studies is about 0.15. Overall, this study provides a theoretical underpinning for understanding the entrainment behavior of thermals, relevant to buoyantly driven atmospheric flows. Significance Statement Thermals, which are coherent, quasi-spherical regions of upward-moving buoyant fluid, are a key feature of many convective atmospheric flows. The purpose of this study is to characterize how thermals entrain surrounding fluid and spread out as they rise. We use theory and numerical modeling to explain why entrainment rate decreases with an increase in the initial thermal aspect ratio—the ratio of height to width. This work also explains why the nondimensional spreading rate (change in thermal radius with height) of initially spherical thermals from past laboratory and numerical modeling studies is about 0.15. Overall, this work provides a framework for conceptualizing the entrainment behavior of thermals and thus improved understanding of vertical transport in convective atmospheric flows.

Epidemic spreading on coupling network with higher-order information layer

Epidemic tends to break out with information spreading which occurs between pairwise individuals or in groups. In active social online platform, three or more individuals can share information or exchange opinion, which could be modeled as a clique beyond pairwise interaction. This work studies the influence of information with higher-order cliques whose closure probability is described by higher-order clustering coefficient on epidemic spreading. The coupled spreading process of disease and awareness follows an unaware-aware-unaware-susceptible-infected-susceptible model on multiplex networks. We deduce the epidemic threshold of multiplex network with higher-order cliques, and explore the effects of cliques on epidemic spreading process at slow, middle and fast pairwise information spreading rates. The results show that the epidemic threshold and higher-order clustering coefficient are positively correlated. Moreover, we find that the effect of higher-order cliques could be ignored when pairwise information spreading rate is large enough. Finally, we show that the steady infection ratio decreases with the increase of the higher-order clustering coefficient.

Assessment of iron and heavy metals accumulation in the soils of the combat zone

The object of the study is soils in areas with active military operations. The study is dedicated to assessing the environmental impact of military operations through forecasting. The paper highlights the impact of military conflict on the distribution of heavy metals in soils. An analysis of the distribution and interaction of heavy metals in soil is carried out, which helps to understand the dynamics of pollution in the context of military conflict, and allows to understand the complex processes of the impact of military operations on the environment and the state of soil resources. The complex interrelationships between military operations and environmental pollution are revealed, with an emphasis on the importance of studying the distribution and immobilization of iron and heavy metals in the current conditions of the risk of military operations. It is shown that the most rapidly distributed metals in the soil are: iron (Fe), zinc (Zn), cadmium (Cd), antimony (Sb); the slowest: arsenic (As), lead (Pb), copper (Cu), nickel (Ni), mercury (Hg), manganese (Mn), vanadium (V). It was found that loams and chernozems are more prone to the accumulation of heavy metals and iron than sandy soils. Compared to sandy soil, the rate of metal release in loam decreases from 16.7 % to 69.7 %. In comparison of chernozem to loam, the release rate slows down from 17.85 % to 32.08 %. It was found that the rate of spreading of barium, cobalt, arsenic, lead, mercury, manganese, strontium and titanium does not depend on the type and mechanical parameters of the soil. The practical use of the results will help to predict the mechanism of pollution spread and help to identify the highest risk areas. The results of the study indicate the need to develop scientifically sound strategies for environmental protection and promotion of sustainable development in the area affected by military events

Beyond spreading rate: Controls on the thermal regime of mid-ocean ridges.

The thermal state of mid-ocean ridges exerts a crucial modulation on seafloor spreading processes that shape ~2/3 of our planet's surface. Standard thermal models treat the ridge axis as a steady-state boundary layer between the hydrosphere and asthenosphere, whose thermal structure primarily reflects the local spreading rate. This framework explains the deepening of axial melt lenses (AMLs)-a proxy for the basaltic solidus isotherm-from ~1 to ~3 km from fast- to intermediate-spreading ridges but fails to account for shallow crustal AMLs documented at slow-ultraslow spreading ridges. Here, we show that these can be explained by a numerical model that decouples the potentially transient ridge magma supply from spreading rate, captures the essential physics of hydrothermal convection, and considers multiple modes of melt emplacement. Our simulations show that melt flux is a better thermal predictor than spreading rate. While multiple combinations of melt/dike emplacement modes, permeability structure, and temporal fluctuations of melt supply can explain shallow crustal AMLs at slow-ultraslow ridges, they all require elevated melt fluxes compared to most ridge sections of comparable spreading rates. This highlights the importance of along-axis melt focusing at slow-ultraslow ridges and sheds light on the natural variability of their thermal regimes.

Conformity versus credibility: A coupled rumor-belief model

The opinion individuals hold about circulating information moderates their spreading behavior, as they may choose to spread rumors they believe in and remain silent about those they do not. Meanwhile, these opinions may be influenced by peers’ opinions and observed behaviors. We present coupled dynamics that integrate opinion formation and information spreading within two-layer multiplex social networks. In an influence layer, opinions are shaped by information credibility and social influence, the degree of which is determined by individual tendencies to conform. In a communication layer, information spreads conditioned on whether individuals believe in it. Using analytical and numerical tools, we demonstrate consistent behavior of the model by identifying the criteria for an evolutionary advantage in opinion formation and a critical spreading rate for rumor outbreaks. We then proceeded to examine two scenarios distinguished by considering credibility as either an intrinsic or a social property of information. Our results show that, for intrinsic credibility, higher degrees of conformity promote the spread of incredible information and inhibit the diffusion of credible information; for social credibility, higher degrees of conformity have an amplifying effect on the evolution of belief and rumor spreading. Additionally, the former scenario exhibits rich behaviors in the interplay between opinion evolution and information spreading, including paradigm shift, passive support, and fringe belief. We thus contribute to the understanding of the dynamics of opinion formation and information propagation in social groups. Empirical application may inform efforts to assess and combat the spread of misinformation.

EFFECT OF FREE-FLOATING PLANTS ON WEED EMERGENCE, GROWTH, AND YIELD OF TRANSPLANTED AMAN RICE VARIETIES

At Sher-e-Bangla Agricultural University’s agronomy field in Dhaka, Bangladesh, a study was carried out from July to December 2019 to determine the suppressing capacity of floating weeds in T. aman rice (Oryza sativa L.). The experiment consisted of two factors, namely, rice varieties (three), including Tulshimala, BR11(Mukta), and Bangladesh Rice Research Institute (BRRI) hybrid dhan6, and weed management (five), including weedy check (control), integrated weed management (IWM) (Pretilachlor 6% + pyrazosulfuron 0.15% and one hand weeding), spreading of Pistia stratiotes, Lemna minor, and Salvinia molesta in 0.5 m2 area in a split-plot design with three replications. The ranking of the relative rate of spreading over the experiment was L. minor &gt; S. molesta &gt; P. stratiotes. A total of six weed species representing five families were found from the transplanting to the later stage of rice growth, where the occurrence of weed infestation related to rice variety and crop growth. BRRI hybrid dhan6 significantly suppressed weeds in related plots. Although weed biomass was significantly reduced, the morphological and biomass characteristics of T. aman rice varieties got disadvantages when grown with P. stratiotes and S. molesta. Cultivation of BRRI hybrid dhan6 and weed control through IWM gave the highest grain yield (5.92 t ha-1). However, the spreading of L. minor facilitated optimal weed control, and good yields were harvested without significant differences, irrespective of varieties. Therefore, competitive weed variety should be considered along with the spreading of L. minor to reduce herbicide loads in the environment and to the evolution of cross-resistant weed populations.

Deformation rate of engineered wood flooring with response surface methodology and adaptive network-based fuzzy inference system.

Controlling the deformation rate is the key to improving the product quality of engineered wood flooring. In this work, the changes in the deformation rate of engineered wood flooring were in focus with cold-pressing, response surface methodology, and adaptive network-based fuzzy inference system were used to explore the relationship between deformation rate and processing parameters, including adhesive spreading rate, pressing time, and pressing pressure. According to the results, the deformation rate was positively related to pressing time, while it increased first and then decreased with both the increase of adhesive spreading rate and pressing pressure. Meanwhile, a mathematical model was developed, and the significant influence of each term on the deformation rate was analyzed. This model had high feasibility and can be used to describe the relationship between the deformation rate and processing parameters. Furthermore, an adaptive network-based fuzzy inference system model was established. It has higher accuracy than that of the response surface methodology model, and it can be used for predicting deformation rate and optimizing processing parameters. Finally, an optimal processing conditions with the lowest deformation rate was determined as follows: 147 g/m2 adhesive spreading rate, 12s pressing time, and 1.2 MPa pressing pressure, and it hope to be adopted in the industrial processing of engineered wood flooring with respective of the higher product quality and lower production costs.

The formation and growth mechanisms of young back-arc spreading ridges from high-resolution bathymetry: The Marsili Seamount (Tyrrhenian Sea, Italy)

The formation and growth mechanisms of Mid-Ocean Ridges (MOR) are relatively well known, whereas those of back-arc spreading ridges are comparatively less known because geophysical, geochemical, and morphological data are scarce and of low density. Here we present a high-resolution bathymetry of the Marsili Seamount (MS; 1 Ma − 3 ka), which represents the inflated spreading ridge of the 2 Ma old Marsili back-arc basin associated to the subduction of the Ionian Sea below the Calabrian Arc and Tyrrhenian Sea. MS is 70 km long, 30 km wide, and its height reaches about 3000 m from surrounding seafloor. Our new digital bathymetric model has a 5 m grid cell size resolution and covers the MS bathymetry from −1670 mbsl to the top at −491 mbsl. We conduct morphometric and morphological analyses of the bathymetry and recognize landforms due to volcanic, tectonic, hydrothermal and gravity processes. MS consists of volcanoes related to fissural and central-type activity, this latter located at the northern and southern tips of the main dike swarms. Dike swarms represent the surface expression of different ridge segments whose strikes are controlled by the larger scale back-arc spreading processes and by the local occurrence of an active hydrothermal field. This latter develops in a flat area between two partly overlapping ridge segments where historical volcanism and extensional processes concentrate. Such ridges represent the embryonic stage of the formation of transform-like faults. Central volcanoes, the northern of which is characterized by a caldera, form at the tips of MS because the decrease in width of the major volcanic fissures promotes vent localization associated with the formation of sill-like reservoirs from which central-type vents may develop. Gravity processes affecting the MS flanks are due to shallow seafloor sliding. Caldera collapses affecting the northernmost central-type polygenic volcano must be included in the evaluation of the hazard related to potential tsunami. Inward dipping faults characterize the MS eastern flank suggesting a moderately asymmetric growth of the spreading ridge possibly associated with the eastward opening of the Marsili back-arc.The Marsili back-arc spreading rate is similar to those of MOR slow spreading ridges. However, the MS morphology resembles that of fast spreading ridges. These two features also characterize more extended back-arc spreading ridges (e.g. the Mariana in Western Pacific). We conclude that, independently from the spatial scale, the increase in the ridge accretion rate is related to the progressive addition of a subduction-related component to a pure spreading mantle source.

Seafloor spreading and the delivery of sulfur and metals to Earth’s oceans

Abstract Circulating fluids within Earth’s mid-ocean ridge system cool and alter the oceanic crust, contribute distinct chemistry to the ocean, and generate economically and geologically important metal-sulfide deposits at the seafloor. Yet, we have few constraints on the characteristics of these fluids at peak subseafloor pressure and temperature conditions or how the primary variable, seafloor spreading, affects these fluids’ delivery of metals and sulfur to seawater. Here, we develop a new, robust technique for estimating the peak endowment of heat and dissolved sulfur, iron, and copper in subseafloor hydrothermal fluids and determining their fate as these superheated fluids rise to the seafloor. Calculations using this technique indicate that &amp;gt;20%–70% of sulfur, iron, and copper dissolved at peak subseafloor conditions are lost during upflow due to cooling and concomitant decreases in sulfide mineral solubility. The interpretation of these estimates within the geologic context of vent fields allows us to demonstrate a strong inverse relationship between seafloor spreading rate and peak pressure-temperature conditions, subseafloor heat loss, and the magnitude of subseafloor sulfide mineralization. Our results demonstrate the extent to which the secular variation of Earth’s mid-ocean ridge system over geologic time has impacted sulfide deposition rates and hydrothermal fluxes of sulfur and metals to the ocean.

Tuning rheology and fire-fighting performance of protein-stabilized foam by actively switching the interfacial state of the liquid film

Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dispersions with unique functional characteristics. In this work, protein-metal coordination complexes were designed as the stabilizer for generating ultrastable fire-fighting foam and creating interfacial architectures that were actively switched between “rigid” and “mobile” interfacial states of liquid films in response to changes in pH and bulk solution compositions (metal ions or alkyl polyglycosides). The reflected light interferometric technique was used to check interfacial states, and the foaming kinetics and rheological response of aqueous solution and liquid foam were investigated by dynamic surface tension tests and oscillatory rheology analysis. The results showed that liquid foams with mobile films with lower yield limits had a faster spreading rate to cover the burning oil, liquid foams with semi-rigid films cannot extinguish fires due to interfacial instability, and the enhanced rheology of the foam with rigid films established a robust and impenetrable barrier to effectively suppress fuel evaporation and combustion. A new correlation between interfacial properties and the fire-fighting performance of foam was proposed, which showed that the fire-extinguishing time of foam could be well correlated by the interfacial states or film lifetime rather than classical thermodynamics entry, spreading, and bridging coefficients (ESB coefficients).

Effect of Shape and Size on the Transport of Floating Particles on the Free Surface in a Natural Stream

AbstractUnderstanding how floating particles are transported by streaming waters is crucial in predicting the transport of plastic pollution, which is dramatically abundant in rivers, lakes, and oceans. Using particle tracking velocimetry, we investigate the motion of floating particles of different shape and size on the turbulent free surface of a field‐scale meandering stream. We consider two different locations, where the role of surface waves on transport is deemed negligible. Millimeter‐sized spheres are used as tracers to characterize the surface flow. These are compared with centimeter‐sized discs and rods, approximating typical‐sized pieces of floating litter. The larger particles exhibit similar mean and fluctuating velocities as the tracers but filter out the extreme turbulent accelerations. Consequently, their motion is more time‐correlated and their spreading rate is larger. This behavior is also confirmed by complementary laboratory measurements in an open channel flow. The rotation of the rods, affected by a range of turbulent scales, reduces the correlation time scale of their translational motion, and leads to a slower dispersion compared to the discs, despite the rods' length being larger than the discs' diameter. Taken together, these results indicate that the motion of finite‐sized objects floating on the surface of weakly wavy turbulent waters is consistent with the behavior of inertial particles in three‐dimensional turbulence. These results can be valuable when constructing predictive models of floating plastics.

Wetting Behavior of CO2 Droplets on Smooth Solid Surface: Molecular Simulation Perspective

The wettability of droplets on solid surfaces is important for accurately revealing the microscopic mechanisms of gas condensation nucleation and droplet growth. During the contact condensation of CO2 gas on the heat exchanger surface in the pressurized liquefied natural gas technology, the wettability of CO2 droplets on the heat exchanger surface directly affects the heat transfer thermal resistance of the heat exchanger, which then affects the heat transfer efficiency of methane and ethane in the heat exchanger. Therefore, molecular dynamics simulations were used to study the spreading process and wetting patterns of nanoscale CO2 droplets on different energy surfaces. The results show that as the potential well depth ε of the wall atoms increases, the intensity of the solid-liquid interaction increases and the corresponding surface energy increases accordingly, showing different droplet spreading rates and wetting characteristics. Unlike the interfacial characteristics of macroscopic droplets, there are significant fluctuations at the gas-liquid interface of droplets on the molecular scale, but microdroplets can still form a specific contact angle after spreading on different energy surfaces in a statistical sense, and this contact angle decreases with increasing intensity of solid-liquid interaction. The low-energy surface at potential well depths ε less than 266 J·mol-1 exhibits a CO2-phobicity, and the surface becomes CO2-philic as the potential well depth continues to increase. The trend of the contact angle of CO2 droplets affected by temperature is the same as that of the center-of-mass height, which characterizes the spreading morphology of CO2 droplets. As the temperature increases, the contact angle decreases due to the further spreading and wetting of droplets on different energy surfaces. As the CO2-philicity of the surface gets higher, the contact angle decreases to a greater extent.

Impact of Oil Viscosity on Dispersion in the Aqueous Phase of an Immiscible Two‐Phase Flow in Porous Media: An X‐Ray Tomography Study

AbstractIn this study, dispersion and mixing were studied in a steady two‐phase flow generated using a co‐injection method. The impact of oil viscosity was investigated over a large range of fluid viscosity ratios. The results indicate that highly heterogeneous flow fields are generated by a wide distribution of oil clusters with varied volumes. Variation in the velocity distribution enhanced the deformation and spreading of a tracer plume, resulting in large dispersion scales and accelerated spreading rates. The dispersion coefficients vary with time and exhibit a non‐Fickian dispersion during co‐injection. Consequently, anomalous mixing behaviors can be observed when the viscosity ratio exceeds 10. The mixing strength, characterized by the scalar dissipation rate, is first enhanced by distortion on the surface of the solute. Therefore, diffusion contributes to mixing, resulting in a faster decrease in the mixing strength in the late time regime. These results can be attributed to the fact that the non‐wetting fluid becomes disconnected, and the size of each cluster decreases as the oil viscosity increases. The formation of an oil film narrows pore spaces, and a lubrication effect of the oil film may contribute to the enhanced dispersion and mixing state, even with the low relative permeability of the wetting phase. This study provides insights into dispersion in partially saturated porous media with varied oil viscosities at both the macro and pore scales, which can further improve CO2 storage capacity and safety.

Algorithms for decision-making process using complex Pythagorean fuzzy set and its application to hospital siting for COVID-19 patients

Since the start of COVID-19, a fair amount of work has been undertaken by scholars around the world to model its progression. It became clear from the start of pandemic that its progression is affected by various factors within different communities. Subsequently, the necessary means and the range of measures used to effectively control the virus would vary from place to place. And we have been witness to different approaches adopted around the world to maintain the virus under check both in the short term and the long term. So, in this unexpected situation, it is a great challenge for the world health organization (WHO) to save the lives of COVID-19 patients. For this, several mathematical models have been made for better understanding the coronavirus contagion. Mostly, these models are based on classical integer-order derivative using real numbers which cannot capture the fading memory. Thus, in this unexpected situation, fuzzy sets (FSs) are considered due to their inherent capability to deal with uncertainty. Fuzzy sets (FSs) theory has the ability to manage uncertain situations. Thus, the goal of this research is to present newly mathematical methods based on complex Pythagorean fuzzy sets (CPyFSs) and their operators, namely complex Pythagorean fuzzy Einstein weighted geometric operator, and induced complex Pythagorean fuzzy Einstein hybrid geometric operator to reduce the spreading rate of COVID-19. At the end of the paper an illustrative example is constructed to show the effectiveness, reliability of the new techniques.

Modeling the competitive propagation of rumors and counter-rumors in two-layer complex networks with nonlinear spreading and decay rates

Prior investigations into the propagation of rumors have predominantly focused on either online or offline social networks, neglecting the concurrent dissemination of rumors and counter-rumors. Hence, to investigate how rumors and counter-rumors spread and interact in online and offline two-layer networks, and to devise an optimal control strategy for rumors, we propose a nonlinear SEIDR spreading model that incorporates the effects of social reinforcement and interest decay. By constructing mean-field equations, we present the mathematical expression of the SEIDR model and further define and compute the basic reproduction number of rumors. Subsequently, three theorems related to the final scale of rumors are introduced. Finally, we investigate the primary factors influencing rumor propagation via Monte Carlo simulations, yielding the following key findings: (i) The final scale of rumors exhibits a positive correlation with the social reinforcement effect and the second-order moment of the network, while displaying a negative correlation with the interest decay effect and the average degree of the network. (ii) The final scale of rumors ranks in the order of: random network > scale-free network > small-world network > regular network. (iii) Notably, the speed of rumor propagation aligns with the order: scale-free network > random network > small-world network > regular network.