Dynamical Evolution Research Articles

Strong effect of often-overlooked initial spilled oil distribution on subsequent soil remediation: A pore-scale perspective

The removal of spilled oil within soil by water injection is essentially an immiscible fluid displacement process. Numerous studies have been conducted to investigate the way to achieve a higher displacement efficiency. However, these studies often assumed that the pore space was initially saturated by oil only, ignoring the effect of initial oil distribution on the remediation, which led to incorrectly computed flow field and biased analysis. This work aimed to reveal the effect of initial oil distribution on flow physics during the remediation. Based on a pore-scale model and the phase-field method, the spilled oil invasion and remediation in a heterogeneous porous media were investigated, and the dynamic evolution of the phase interface was examined in particular. Four different distribution patterns of spilled oil were obtained through various velocities during the oil invasion stage, which were considered as initial states for the subsequent remediation stage. The results showed that ignoring the oil invasion process led to a more than 10% reduction in the ultimate remediation efficiency. However, the maximum interfacial area of fluids was larger and the obtained relative permeability curve was much smoother for the scenario considering the oil invasion. Besides, a higher initial water saturation led to a lower starting pressure. This work provided new pore-scale insights into the often-overlooked roles of initial phase distribution in fluid dynamics behind the remediation of oil-contaminated soil by water injection, which was of fundamental importance to the development of effective response strategy for soil contamination.

Early warning and dynamics of compound rockslides: lessons learnt from the Brienz/Brinzauls 2023 rockslope failure

AbstractPrediction of rockslope dynamic evolution and catastrophic failure remains a fundamental challenge for scientists and practitioners, even though this topic has been studied for decades. Here we report about a case in the Swiss Alps, which has received worldwide attention, not only because a village was evacuated on May 12, 2023, and traffic corridors were progressively closed prior to the slope collapse, but also because this site had been studied and monitored with unprecedented detail during many years before failure. In 2023 the structural and dynamic evolution of the 2 million m3 suspended compound rockslide at Brienz/Brinzauls was closely monitored with diverse ground-based systems and continuously modeled with Voight’s creep law. Substantial deviations from this classical failure model were observed, which are in most cases not related to variations in external driving factors, but diverse internal strength degradation processes. This led to a systematic analysis of Voight’s model uncertainty and the development of an early warning system which includes supplementary early warning parameters to the classical velocity thresholds. We show how to treat the spatial and temporal variations of velocity thresholds and when they reach their applicability limit in a real-time early warning model. The unstable compartment at Brienz/Brinzauls progressively collapsed in the night of June 15, 2023, and generated a series of dry granular flows and rock mass falls, which just stopped at the Brienz settlement boundary.

Study on corrosion behavior and first-principle analysis of M50 steel in lubricating oil contaminated by salt water

The corrosive wear of M50 steel in lubricating oil contaminated with saline is a form of wear that often occurs within the main shaft bearings of aviation engines carried by aircraft working at sea. In the present paper, the corrosion behavior of M50 steel in lubricating oil contaminated with saline was studied. The open-circuit potential, polarization curve and impedance spectrum were analyzed by rotating electrochemical corrosion wear test. A three-layer interface microscopic molecular model was established with Materials Studio to simulate the dynamic corrosion evolution process of M50 steel self-matching pairs and the adsorption energy was calculated. The results show that the corrosion type is pitting corrosion. With the increase of saline concentration, the corrosion area becomes wider and shallower, and the size of the pitting core gradually decreases. The weight loss of M50 steel increases over time, but the trend slows down, which is also shown in the MS simulation results. Electrochemical tests show that the tribocorrosion of M50 steel is related to load, speed. As the load increases, the corrosion rate decreases. And, as the speed increases, the corrosion rate increases. This has practical significance for extending the understanding of tribocorrosion of M50 steel in marine atmospheric environments.

Dynamics of VLS-Grown Si Nanowires: Insights from Molecular Dynamics Simulations on Facet Evolution, Twinning, Nucleation, and Impurity Dynamics

Dynamics of VLS-Grown Si Nanowires: Insights from Molecular Dynamics Simulations on Facet Evolution, Twinning, Nucleation, and Impurity Dynamics

Navigating New Waters: Russian Military Aggression on Ukraine and Effects on the Visegrad Group

In this article, the author examines the dynamic evolution of the Visegrad Group (V4) countries in response to Russia's war on Ukraine. Although V4 cooperation is deeply rooted in shared historical experiences, recent geopolitical challenges have revealed significant differences among member countries. Poland and the Czech Republic are strongly supportive of Ukraine and oriented towards NATO, while Hungary and Slovakia are more ambivalent, creating internal tensions. The author examines the factors that shape national identities and their influence on these divergent responses, highlighting that these factors have implications for the future of the V4 countries. The researcher used mixed methods to analyse official documents, political speeches and opinion poll data from the V4 countries, to examine the impact of Russia's invasion of Ukraine on V4 unity and solidarity, and to consider the implications for the future of the V4 countries. The findings point to a fragile unity and growing concerns about the V4's ability to respond coherently to external threats.

The alterations of repetitive transcranial magnetic stimulation on the energy landscape of resting-state networks differ across the human cortex.

Repetitive transcranial magnetic stimulation (rTMS) is a promising intervention tool for the noninvasive modulation of brain activity and behavior in neuroscience research and clinical settings. However, the resting-state dynamic evolution of large-scale functional brain networks following rTMS has rarely been investigated. Here, using resting-state fMRI images collected from 23 healthy individuals before (baseline) and after 1 Hz rTMS of the left frontal (FRO) and occipital (OCC) lobes, we examined the different effects of rTMS on brain dynamics across the human cortex. By fitting a pairwise maximum entropy model (pMEM), we constructed an energy landscape for the baseline and poststimulus conditions by fitting a pMEM. We defined dominant brain states (local minima) in the energy landscape with synergistic activation and deactivation patterns of large-scale functional networks. We calculated state dynamics including appearance probability, transitions and duration. The results showed that 1 Hz rTMS induced increased and decreased state probability, transitions and duration when delivered to the FRO and OCC targets, respectively. Most importantly, the shortest path and minimum cost between dominant brain states were altered after stimulation. The absolute sum of the costs from the source states to the destinations was lower after OCC stimulation than after FRO stimulation. In conclusion, our study characterized the dynamic trajectory of state transitions in the energy landscape and suggested that local rTMS can induce significant dynamic perturbation involving stimulated and distant functional networks, which aligns with the modern view of the dynamic and complex brain. Our results suggest low-dimensional mapping of rTMS-induced brain adaption, which will contribute to a broader and more effective application of rTMS in clinical settings.

Different manifestations of a loop-like transient brightening in solar atmospheres

Small-scale transient brightenings that are the consequence of magnetic reconnection play pivotal roles in the heating process of solar atmospheres. These phenomena contain key information about the dynamic evolution of the solar magnetic field. The fine-scale structures triggered by instabilities in these brightenings are intimately connected with the release of magnetic energy. To better understand the conversion and release of magnetic energy in small-scale heating events, we investigated the thermal-dynamical behaviors of a loop-like transient brightening (LTB) with plasma blobs. We used the spectroscopic and slit-jaw imaging observations taken from the Interface Region Imaging Spectrograph and the extreme-ultraviolet images taken from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to analyze the plasma properties of an LTB that occurred on February 28, 2014. The space-time maps were created to present the spatial evolution of the LTB, and the light curves were calculated to illustrate the heating process. Additionally, we employed the differential emission measure (DEM) method to compute the temperature and emission measure of the LTB. In order to investigate the plasma motion along the line-of-sight direction, a double-Gaussian function was used to fit the Si IV spectral profiles. The spectrum and DEM analysis indicate that the LTB was constituted by multithermal plasma with temperatures reaching up to $5.4 $ K. The space-time maps of the emission and the Gaussian-fitting results of the Si IV line demonstrate that the LTB not only exhibited bidirectional flows, but was also twisted. Several plasma blobs were identified in the spine of the LTB, suggesting the potential presence of a tearing-mode instability. The low-temperature bands peaked approximately one minute prior to the high-temperature bands, suggesting the occurrence of a heating process driven by magnetic reconnection. The appearance of plasma blobs closely coincided with the sudden increase in the velocity and the quick rise of light curves, providing evidence that plasma blobs facilitate the release of magnetic energy during solar activity. Based on these findings, we speculate that the LTB was a complex structure that occurred in the upper chromosphere-transition region. These results clearly demonstrate that plasma blobs are important for the conversion and release processes of magnetic energy.

Dynamic Evolution and Driving Forces of the Changes in Lakeside Wetlands in the Mongolian Plateau

Dynamic Evolution and Driving Forces of the Changes in Lakeside Wetlands in the Mongolian Plateau

Dynamic Evolution of Antisite Defect and Coupling Anionic Redox in High-Voltage Ultrahigh-Ni Cathode.

High-voltage ultrahigh-Ni cathodes (LiNixCoyMn1-x-yO2, x≥0.9) can significantly enhance the energy density and cost-effectiveness of Li-ion batteries beyond current levels. However, severe Li-Ni antisite defects and their undetermined dynamic evolutions during high-voltage cycling limit the further development of these ultrahigh-Ni cathodes. In this study, we quantify the dynamic evolutions of the Li-Ni antisite defect using operando neutron diffraction and reveal its coupling relationship with anionic redox, another critical challenge restricting ultrahigh-Ni cathodes. We detect a clear Ni migration coupled with an unstable oxygen lattice, which accompanies the oxidation of oxygen anions at high voltages. Based on these findings, we propose that minimized Li-Ni antisite defects and controlled Ni migrations are essential for achieving stable high-voltage cycling structures in ultrahigh-Ni cathodes. This is further demonstrated by the optimized ultrahigh-Ni cathode, where reduced dynamic evolutions of the Li-Ni antisite defect effectively inhibit the anionic redox, enhancing the 4.5 V cycling stability.

Using In situ Transmission Electron Microscopy to Study Strong Metal-Support Interactions in Heterogeneous Catalysis.

Precisely controlling the microstructure of supported metal catalysts and regulating metal-support interactions at the atomic level are essential for achieving highly efficient heterogeneous catalysts. Strong metal-support interaction (SMSI) not only stabilizes metal nanoparticles and improves their resistance to sintering but also modulates the electrical interaction between metal species and the support, optimizing the catalytic activity and selectivity. Therefore, understating the formation mechanism of SMSI and its dynamic evolution during the chemical reaction at the atomic scale is crucial for guiding the structural design and performance optimization of supported metal catalysts. Recent advancements in in situ transmission electron microscopy (TEM) have shed new light on these complex phenomena, providing deeper insights into the SMSI dynamics. Here, the research progress of in situ TEM investigation on SMSI in heterogeneous catalysis is systematically reviewed, focusing on the formation dynamics, structural evolution during the catalytic reactions, and regulation methods of SMSI. The significant advantages of in situ TEM technologies for SMSI research are also highlighted. Moreover, the challenges and probable development paths of in situ TEM studies on the SMSI are also provided.

Enhanced CO2 hydrogenation reaction by Tuning interfacial Cu/ZnOx through synergistic interactions in the precursors

The Cu/ZnO/Al2O3 is a typical industrial catalyst for water–gas-shift reaction and methanol synthesis, and is also gaining momentum in CO2 hydrogenation reaction. The dynamic evolution of the phases and microstructures of the precursor of this catalyst leads to a notable synergistic effect that defines its overall catalytic function and performance. To gain insights into the role and interaction between the relevant precursors, we compared Cu/ZnO/Al2O3 catalysts using a conventional co-precipitation and a fractional precipitation method, where the latter one shows an enhanced Cu/ZnOx interface due to a thorough and strong interaction between two components in the precursor. The ZnOx decoration on Cu with unsaturated Znδ+ species boosted the methanol formation to a rate of 508 gCH3OH‧kgcat−1‧h−1 with 58 % selectivity at 513 K and 3 MPa. This work provides mechanistic insights into the synergistic interplay between the involved phases in the Cu/ZnO/Al2O3 catalyst.

Entanglement of Coupled Harmonic Oscillators without and with Tunneling Effect and Correction Factor

Seeing its simplicity of processing, the system of two coupled harmonic oscillators have witnessed a quick growth of research conducted to quantum information. This approach is explicitly investigated in this paper, in particularly entanglement concept is proved to be intimately related to the tunneling effect. We examine analytically entanglement dynamics by introducing the Lewis and Riesenfeld invariant operator in the Heisenberg picture approach to compute the density matrix on the based of an exact treatment. We use Wigner function of the mixed state as an essential tool to move to linear entanglement entropies and we compute the corresponding correction factor. We follow numerically the evolution of entanglement dynamics without and under tunneling through the quantum potential barrier by introducing two particular models between simple and damped coupled harmonic oscillators. Entanglement dynamics is considered to be average without tunneling, it grows upon encountering the potential barrier and remains moderately constant inside barrier. This specificity is extended for both models but with higher values for damped coupled harmonic oscillators consequently the damping effect rapidly increases entanglement. Correction factor is also considered for both models, it show that; low temperature and high potential barriers make the system more disruptive. An increase of the coupling parameter of the system increase correction factor. Damping make the correction factor more important so damping disturbs more the system. Interference effect increase correction factor and it shows an interference between the values of the barrier penetration integral.

Apollo: A comprehensive GPU-powered within-host simulator for viral evolution and infection dynamics across population, tissue, and cell.

Modern sequencing instruments bring unprecedented opportunity to study within-host viral evolution in conjunction with viral transmissions between hosts. However, no computational simulators are available to assist the characterization of within-host dynamics. This limits our ability to interpret epidemiological predictions incorporating within-host evolution and to validate computational inference tools. To fill this need we developed Apollo, a GPU-accelerated, out-of-core tool for within-host simulation of viral evolution and infection dynamics across population, tissue, and cellular levels. Apollo is scalable to hundreds of millions of viral genomes and can handle complex demographic and population genetic models. Apollo can replicate real within-host viral evolution; accurately recapturing observed viral sequences from an HIV cohort derived from initial population-genetic configurations. For practical applications, using Apollo-simulated viral genomes and transmission networks, we validated and uncovered the limitations of a widely used viral transmission inference tool.

A New Approach of Data-driven Simulation and Its Application to Solar Active Region 12673

Abstract The solar coronal magnetic field is a pivotal element in the study of eruptive phe-
nomena, and understanding its dynamic evolution has long been a focal point in solar physics.
Numerical models, driven directly by observation data, serve as indispensable tools in investi-
gating the dynamics of the coronal magnetic field. This paper presents a new approach to elec-
tric field inversion, which involves modifying the electric field derived from the DAVE4VM
velocity field using ideal Ohm’s law. The time series of the modified electric field is used as
a boundary condition to drive a full MHD data-driven model, which is applied to simulate
the magnetic field evolution of active region 12673. The simulation results demonstrate that
our method enhances the magnetic energy injection through the bottom boundary, as com-
pared with energy injection calculated directly from the DAVE4VM code, and reproduce of
the evolution of the photospheric magnetic flux. The coronal magnetic field structure is also
in morphological similarity to the coronal loops. This new approach will be applied to the
high-accuracy simulation of eruption phenomena and provide more details on the dynamical
evolution of the coronal magnetic field.

Research on Damage Evolution Mechanism of Layered Rock Mass under Blasting Load

Rock mass consists of many discontinuities, such as faults, joints, etc., and layered joints are a common kind of rock mass structure. The joints affect the stress wave propagation, and blasting is an economical and efficient rock fragmentation method for rock mass engineering. So, the rock mass fragmentation effect and construction progress are affected by these layered joints. Numerical studies were carried out to analyze the damage evolution process of intact rock and rock mass with layered joints subjected to blasting loads based on the Riedel–Hiermaier–Thoma (RHT) model in LS-DYNA software (smp s R11.0.), and the effects of the location of initiation points and the fracture distribution on dynamic damage evolution of the rock mass were discussed. Bottom initiation tends to direct the blasting energy toward the blasthole mouth, resulting in effective rock fragmentation and ejection. Gradually adjusting the initiation point upward can improve the stress and damage distribution, allowing some of the blasting stress waves to propagate toward the bottom and enhance the fragmentation of the rock at the bottom. The distribution of layered joints exacerbates the damage to the rock mass on the upstream surface, but also acts as a certain shield to the propagation of stress waves, increasing the asymmetry of the damage distribution. It is useful to know the damage mechanism of the rock mass with layered joints to improve the effect of rock mass fragmentation by blasting. These results have very important theoretical significance and application value for the optimization of blasting construction technology.

Dynamical Evolution of Four Old Galactic Open Clusters Traced by Their Constituent Stars with Gaia DR3

We investigate the evolutionary stages of four open clusters—Berkeley 39, Collinder 261, NGC 6819, and NGC 7789—of ages ranging from 1.6 to 6 Gyr. These clusters have previously been classified into dynamically young and intermediate age groups based on the segregation level of BSS with respect to red-giant-branch stars and main-sequence stars, respectively. We identify members of these four clusters using the ML-MOC algorithm on Gaia DR3 data. To examine the relative segregation of cluster members of different evolutionary stages, we utilize cumulative radial distributions, proper motion distributions, and spatial distributions in galactocentric coordinates. Our analysis shows that Berkeley 39 and NGC 6819 exhibit moderate signs of population-wise segregation from evolved to less-evolved members. NGC 7789 shows signs of mass segregation only in the cumulative radial distributions. On the other hand, Collinder 261 exhibits high segregation of BSS in the cumulative radial distribution, while other populations show the same level of segregation.

Two-phase flow properties for air sheets injected from rectangular slots in high-velocity crossflow

This work presents an experimental contribution towards the understanding of the two-phase jet dynamics in high-speed transverse flows, a field that is essential to many industrial applications. Four slot injectors are the subject of this investigation, which examines air flows as high as 0.05 m3/s and cross flows as high as 6 m/s. Using an invasive optical probe, the study reveals the presence of an air cavity surrounded by a two-phase mixing zone. Analysis of the spatial void fraction reveals counter-rotating vortices that direct bubbles towards their centers while larger bubbles rise to the top of the vein and form an upper zone with a maximum void fraction. The study also looks at the dynamic evolution of air sheet characteristics, which reveals an increasing trend in average void fraction along the flow. The comparison of bubble characteristics of different slots and conditions provides valuable insights into the impact of environment pressure and slot geometry on void fraction and bubble size in two-phase flows. Finally, correlations based on dimensionless numbers generalize the information on bubble characteristics for a wide range of conditions, assisting in estimation and validation in numerical simulations.

Bayesian inference by visuomotor neurons in prefrontal cortex.

Perceptual judgements of the environment emerge from the concerted activity of neural populations in decision-making areas downstream of sensory cortex [1, 2, 3]. When the sensory input is ambiguous, perceptual judgements can be biased by prior expectations shaped by environmental regularities [4, 5, 6, 7, 8, 9, 10, 11]. These effects are examples of Bayesian inference, a reasoning method in which prior knowledge is leveraged to optimize uncertain decisions [12, 13]. However, it is not known how decision-making circuits combine sensory signals and prior expectations to form a perceptual decision. Here, we study neural population activity in the prefrontal cortex of macaque monkeys trained to report perceptual judgments of ambiguous visual stimuli under two different stimulus distributions. We analyze the component of the neural population response that represents the formation of the perceptual decision (the decision variable, DV), and find that its dynamical evolution reflects the integration of sensory signals and prior expectations. Prior expectations impact the DV's trajectory both before and during stimulus presentation such that DV trajectories with a smaller dynamic range result in more biased and less sensitive perceptual decisions. These results reveal a mechanism by which prefrontal circuits can execute Bayesian inference.

Guidelines for Identifying the Structure of Heavy Phenolics in Lignin Depolymerization by using High-Resolution Tandem Mass Spectrometry.

The efficient conversion of lignin contributes to reducing human reliance on fossil energy. As a complicated biopolymer, studies on the mechanism of lignin depolymerization is limited by inadequate structural identification of high molecular weight (MW) products like heavy phenolics. Up to now, no individual method can generate both MW and structural information in operando conditions. As a promising approach, tandem mass spectrometry (MS/MS) techniques can provide structural information via the dissociation of target ions. In this study, MS/MS technique was performed both in offline and in-situ mode during lignin depolymerization. The fundamental guidelines based on MS/MS dissociation principles for typical inter-unit linkages like β-O-4, 5-5, β-β, β-5, and β-1 were well established. Based on that, major phenolic dimers are successfully identified, including chemical formula and types of inter-unit linkages. More significantly, real-time monitoring of structural evolution was achieved by applying in-situ MS/MS analysis during lignin depolymerization. The results show the different evolution pathways of isomers with same chemical formula, confirming that structural changes during lignin depolymerization are common and obvious. Overall, this study develops an advanced strategy for the full-view analysis of lignin depolymerization, achieving the static analysis of composition and structure, both monitoring the dynamic evolution of structures.

Cognition, horizon and practice: formation of the nonsynchronism in theoretical research of information science

Purpose The nonsynchronism in theoretical research of information science (IS) is an interesting phenomenon that has not been sufficiently examined. This study is to reveal the mechanism of its formation from a microscopic perspective.Design/methodology/approach A qualitative research approach was adopted and 22 professors from different IS fields were interviewed. The data were analyzed with a six-step thematic analysis method.Findings The nonsynchronism in IS theoretical research is reflected in three dimensions. Theory cognition and theory practice shape each other under the constraint of theory horizon. Researchers with similar theory cognition and practice form a theoretical generation. The inter-generational gap may exist among IS researchers in different research areas, at different ages, or located in different countries or regions.Research limitations/implications This study reveals the formation mechanism of the nonsynchronism in IS theoretical research from a microscopic perspective of individual researcher’s theory using practice and offers new insights into the dynamics of the structural evolution of IS theoretical knowledge.Practical implicationsThe results of this study can help to promote internal or external communication in IS and enhance theoretical education for doctoral students.Originality/valueThis study identifies and theoretically defines a few core themes, theory horizon, theory cognition, theory practice and theoretical generation, and reveals their relationships. On this basis, a conceptual model of nonsynchronism in theoretical research is developed.