Velocity Maps Research Articles

Rayleigh wave attenuation and phase velocity maps of the greater Alpine region from ambient noise

We use seismic ambient noise data from 724 publicly available broadband seismic stations across central Europe to create detailed phase velocity and attenuation maps of Rayleigh waves, focusing on short periods down to 3 s. We interpret these maps in terms of the underlying physical processes relevant to the nature of continental crust. Through a regionalized interpretation based on tectonic settings, we highlight the significant role of fluid-filled fractures in the attenuation of surface waves. Our findings indicate a close connection between the time elapsed since the last tectonic activity in the European crust and the attenuation coefficient values. Additionally, we observe a pronounced decrease in attenuation coefficient values at periods below 6 s. The anti-correlation between attenuation coefficient and phase velocity in recently active tectonic regions suggests that fluid-filled fractures are likely the dominant factor governing seismic attenuation in the European crust.

Parameter Optimization of Spiral Step Cleaning Device for Ratooning Rice Based on Computational Fluid Dynamics-Discrete Element Method Coupling

Ratooning rice plants have a high moisture content and strong adhesion during harvesting. Traditional cleaning devices are prone to clogging when processing ratooning rice, resulting in a series of problems such as high grain loss rate and high grain impurity rate. In response to the above issues, this article adopts the CFD-DEM coupling method to design a spiral step cleaning device. A detailed analysis was conducted on the influence of the cone angle and thickness of the spiral-stepped skeletons on the flow state, and flow velocity and pressure distribution cloud maps were obtained under different structural parameters. The vortex morphology under different thicknesses of the spiral-stepped skeletons was compared, and the structural parameters of the device were determined. The motion trajectory and distribution of impurity particles under different inlet flow velocities were analyzed using data superposition, and the appropriate inlet flow velocity range was determined. A test bench was built, and a three-factor quadratic regression orthogonal rotation combination experiment was conducted with fan speed, feeding rate, and device inclination angle as experimental factors. The results of the bench test show that the performance index reaches its optimum when the device inclination angle, fan speed, and feeding rate are 2.47°, 2906 r/min, and 4.0 kg/s, respectively. At this time, the grain impurity rate, grain loss rate, and sieve clogging rate are 2.21%, 2.15%, and 3.5%, respectively. Compared to those of traditional cleaning equipment, these value are reduced by 44.5%, 39.6%, and 83.9%, respectively. This study can provide ideas for the design of ratooning rice cleaning devices.

Disk2Planet: A Robust and Automated Machine Learning Tool for Parameter Inference in Disk–Planet Systems

We introduce Disk2Planet, a machine-learning-based tool to infer key parameters in disk–planet systems from observed protoplanetary disk structures. Disk2Planet takes as input the disk structures in the form of 2D density and velocity maps, and outputs disk and planet properties, that is, the Shakura–Sunyaev viscosity, the disk aspect ratio, the planet–star mass ratio, and the planet’s radius and azimuth. We integrate the Covariance Matrix Adaptation Evolution Strategy, an evolutionary algorithm tailored for complex optimization problems, and the Protoplanetary Disk Operator Network, a neural network designed to predict solutions of disk–planet interactions. Our tool is fully automated and can retrieve parameters in one system in 3 minutes on an Nvidia A100 graphics processing unit. We empirically demonstrate that our tool achieves percent-level or higher accuracy, and is able to handle missing data and unknown levels of noise.

Abstract 4135534: Total and Regional Lung Volumes And Pulmonary Blood Flow In Repaired Tetralogy Of Fallot - Smaller Lungs And A Maldistribution of Flow

Introduction: Many pts with repaired tetralogy of Fallot (rTOF) are left with residual pulmonary regurgitation (PR) and poor exercise performance. Small studies in young children suggest that the total lung volume of rTOF pts are smaller than normal and may contribute to these sequelae. As exercise and cardiac performance are intimately related to lung function, it’s surprising that few rTOF studies have investigated cardiopulmonary interactions. Aims: To determine if regional and total lung volumes in rTOF pts are the same size as normals and if the larger amount of forward blood flow courses to the bigger lung. We hypothesized that this may not be the case. Methods: rTOF patients undergoing clinically indicated cardiac magnetic resonance (CMR) were evaluated for lung volumes using dark blood imaging (figure) and blood flow to the branch pulmonary arteries (bPA) using velocity mapping. Significance < P=0.05. Results: Eleven rTOF patients and 25 normal controls were studied. Total control lung volume was significantly larger than those of rTOF. Regional rTOF right and left lung volumes were smaller than their respective control lung volumes, barely missed statistical significance (table). In 6 rTOF pts with CMR prior to and after pulmonary valve replacement (PVR), lung volumes did not differ between the 2 timepoints (1034 vs 998 cc/m 2 respectively). Only 3/11 (27%) rTOF pts had the higher bPA flow coursing to the higher regional lung. The ratio of right bPA forward flow/right lung volume to left bPA forward flow/left lung volume ranged from 0.72-1.51 (ideal balanced flow to each lung would be 1), implying a maldistribution of flow. Conclusion: rTOF patients have smaller total lung volumes than controls with no change after PVR in our study. In addition, only a small proportion of rTOF patients have the larger amount of flow coursing to the larger lung. The ratio of individual bPA flow to individual lung volume implies a maldistribution of pulmonary flow relative to the respective lung volume. Our findings may have implications for timing of PVR, partially explaining PR and poor exercise performance. Flow limiters placed by cath or surgery may be able to redistribute the appropriate flow to regional lung fields.

Emission line velocity, metallicity, and extinction maps of the Small Magellanic Cloud

ABSTRACT Optical emission lines across the Small Magellanic Cloud (SMC) have been measured from multiple fields using the Australian National University 2.3m telescope with the wide-field spectrograph. Interpolated maps of the gas-phase metallicity, extinction, H $\alpha$ radial velocity, and H $\alpha$ velocity dispersion have been made from these measurements. There is a metallicity gradient from the centre to the north of the galaxy of $\sim$−0.095 dex kpc−1 with a shallower metallicity gradient from the centre to the south of the galaxy of $\sim$−0.013 dex kpc−1. There is an extinction gradient of $\sim$−0.086 E(B − V)/kpc from the centre going north and shallower going from the centre to the south of $\sim$−0.0089 E(B − V)/kpc. The SMC eastern arm has lower extinction than the main body. The radial velocity of the gas from the H $\alpha$ line and the H i line have been compared across the SMC. In general there is good agreement between the two measurements, though there are a few notable exceptions. Both show a region that has different radial velocity to the bulk motion of the SMC in the southern western corner by at least 16 km s$^{-1}$. The velocity dispersion from H $\alpha$ and H i across the SMC have also been compared, with the H $\alpha$ velocity dispersion usually the higher of the two. The eastern arm of the SMC generally has lower velocity dispersion than the SMC’s main body. These measurements enable a detailed examination of the SMC, highlighting its nature as a disrupted satellite galaxy.

Strain Partitioning, Interseismic Coupling, and Shallow Creep Along the Ganzi‐Yushu Fault From Sentinel‐1 InSAR Data

AbstractThe Ganzi‐Yushu fault (GYF) is one of the most seismically active fault systems in eastern Tibet, having experienced five M > 7.0 earthquakes over the past 300 years. Here, we use Sentinel‐1 InSAR data spanning from 2014 to 2023 to derive the interseismic velocity fields along the GYF. We calculate the strain rate fields for the entire fault system, which reveal localized strain accumulation along the GYF as well as along two secondary faults within the Bayan Har block. The inversion results obtained from the elastic block model indicate left‐lateral strike slip rates of 4.0–6.5 mm/yr along the GYF and five locked segments distributed along strike. Furthermore, we identify two shallow creeping segments on the InSAR velocity maps. Based on the locations of the creeping sections and their temporal decay characteristics, we infer that the shallow creep along the GYF is afterslip of the 2010 Yushu earthquake.

Mind the Kinematics Simulation of Planet–Disk Interactions: Time Evolution and Numerical Resolution

Planet–disk interactions can produce kinematic signatures in protoplanetary disks. While recent observations have detected non-Keplerian gas motions in disks, their origins are still being debated. To explore this, we conduct 3D hydrodynamic simulations using the code FARGO3D to study nonaxisymmetric kinematic perturbations at two scale heights induced by Jovian planets in protoplanetary disks, followed by examinations of detectable signals in synthetic CO emission line observations at millimeter wavelengths. We advocate for using residual velocity or channel maps, generated by subtracting an azimuthally averaged background of the disk, to identify planet-induced kinematic perturbations. We investigate the effects of two basic simulation parameters, simulation duration and numerical resolution, on the simulation results. Our findings suggest that a short simulation (e.g., 100 orbits) is insufficient to establish a steady velocity pattern given our chosen viscosity (α = 10−3) and displays plenty of fluctuations on an orbital timescale. Such transient features could be detected in observations. By contrast, a long simulation (e.g., 1000 orbits) is required to reach steady state in kinematic structures. At 1000 orbits, the strongest detectable velocity structures are found in the spiral wakes close to the planet. Through numerical convergence tests, we find hydrodynamics results converge in spiral regions at a resolution of 14 cells per disk scale height or higher. Meanwhile, synthetic observations produced from hydrodynamic simulations at different resolutions are indistinguishable with 0.″1 angular resolution and 10 hr of integration time on Atacama Large Millimeter/submillimeter Array.

Ambient Noise Tomography of Northern Borneo Reveals Evidence of Subduction and Post‐Subduction Processes

AbstractThe region of northern Borneo in South East Asia sits within a post‐subduction setting formed by the recent termination of two sequential but opposed subduction systems. In this study we use seismic data from a recent temporary array deployment to image the crustal velocity structure beneath northern Borneo using a two‐stage Bayesian trans‐dimensional tomography scheme, in which period dependent phase velocity maps are first generated, and then used to build a 3‐D shear wave model through a series of 1‐D inversions. In the second stage, we also apply an Artificial Neural Network to solve the 1D inverse problem, which results in a smoother 3‐D model compared to the TransD approach without sacrificing data fit. Our shear wave velocity model reveals a complex crustal structure. Under the Crocker Range, a heterogeneous velocity structure likely represents remnants of early Miocene subduction, including underthrust continental crust from subsequent continent‐continent collision. In the east we observe high velocities that are interpreted to be igneous rocks in the crust generated by melting due to mid Miocene Celebes Sea subduction and later decompression melting as well as a low velocity zone that could represent underthrust sediment or duplexes from Celebes Sea subduction. A low velocity zone in the lower crust is present in a region of apparent crustal thinning. Our preferred explanation for this anomaly is remnant thermal upwelling within a failed rift that represents the on‐shore continuation of the extension of the Sulu Sea, most likely caused by rollback of the Celebes Sea slab.

Parallel Force Feedback Device Design With Constant Jacobian Matrix and Net Weight Fully Balanced

Abstract Force feedback devices offer realistic and intuitive feedback to operators, and achieving higher accuracy and transparency has been a prominent research focus in this field. However, errors in real-time force or position calculations are inevitable, which can have adverse effects on the accuracy of the equipment. This article presents the design of a parallel mechanism that incorporates a constant force and velocity mapping relationship based on the type synthesis of the constant Jacobian matrix. Specifically, the mechanism maintains a fixed direction of force applied to the operating platform by the drive pair, which is mounted on the fixed platform in each limb, irrespective of position changes. This unique feature enables the mechanism to achieve a complete net weight balance. The implementation method is detailed in this article, which involves adding appropriate counterweights to achieve a balance between the weight of the connecting rod and the overall gravity of the operating platform. Furthermore, the optimization of structural parameters helps to improve the performance of the developed prototype. The proposed design scheme not only addresses the fundamental reduction of errors caused by real-time force and position mapping solving but also enhances operational transparency. Finally, simulation and experimental tests are conducted to validate the proposed theory.

Mechanical wave velocities in acute myocardial infarction: an exploratory study using three-dimensional high frame rate echocardiography

Abstract Background Evaluation of cardiac function is crucial for management of patients with acute myocardial infarction (AMI). Recently, high frame rate (HFR) echocardiography has enabled identification of fast-propagating mechanical waves (MW) within the myocardium. These waves have the potential to offer unique insights into myocardial tissue properties, including edema and fibrosis. However, the potential of 3D HFR echocardiography to accurately quantify MW velocities and thereby assess myocardial stiffness in AMI patients remains unexplored. Purpose To assess the feasibility of a novel method for estimating MW velocities using 3D HFR echocardiography in patients with AMI compared to healthy controls. Methods Twenty patients with first time ST-elevation myocardial infarction were included within 48 hours after reperfusion therapy. We used a commercially available ultrasound scanner to acquire conventional 3D high-quality (~20 frames per second) acquisitions and subsequent 3D HFR recordings (~820 frames per second). The high-quality recording was used to extract a myocardial mask to define the region of interest in the HFR acquisition to detect the atrial kick wave and generate a comprehensive 3D map of MW propagation and velocities. We compared MW velocities between these patients and twenty age- and sex-matched healthy controls. Results MW velocities were successfully measured in 93% of participants (17 patients and 20 controls). Global MW velocities were significantly higher in AMI patients compared to healthy controls (2.1±0.6m/s vs. 1.5±0.2m/s, p<0.001). Territorial values, corresponding to the theoretical perfusion area of the three main coronary arteries, were significantly higher in infarct-related territories in patients when compared to same territories in controls for all coronary territories: Right coronary artery: 1.9±0.7 m/s vs. 1.4±0.3m/s, p<0.05; Circumflex artery: 3.1±1.5m/s vs. 1.7±0.4m/s, p<0.01; and Left anterior descending artery: 1.8±0.5m/s vs. 1.4±0.2m/s, p<0.01. Conclusions Estimation of MW velocities using a novel 3D HFR echocardiography method was feasible in most patients with AMI and all healthy controls. MW velocities were higher in patients compared to healthy controls and infarcted compared to non-infarcted coronary territories. These findings confirm the potential of non-invasive myocardial tissue characterization by MW imaging.Boxplot of MW velocities3D HFR MW visualisation

Scalable Copper Sulfide Formulations for Super-Resolution Optoacoustic Brain Imaging in the Second Near-Infrared Window.

Optoacoustic imaging offers label-free multi-parametric characterization of cerebrovascular morphology and hemodynamics at depths and spatiotemporal resolution unattainable with optical microscopy. Effective imaging depth can greatly be enhanced by employing photons in the second near-infrared (NIR-II) window. However, diminished absorption by hemoglobin along with a lack of suitable contrast agents hinder an efficient application of the technique in this spectral range. Herein, copper sulfide (CuS) micro- and nano-formulations for multi-scale optoacoustic imaging in the NIR-II window are introduced. Dynamic contrast enhancement induced by intravenously administered CuS nanoparticles facilitated visualization of blood perfusion in murine cerebrovascular networks. The individual calcium carbonate microparticles carrying CuS are further shown to generate sufficient responses to enable super-resolution microvascular imaging and blood flow velocity mapping with localization optoacoustic tomography.

Observational signatures of circumbinary discs II: Kinematic signatures in velocity residuals

Abstract Kinematic studies of protoplanetary discs are a valuable method for uncovering hidden companions. In the first paper of this series, we presented five morphological and kinematic criteria that aid in asserting the binary nature of a protoplanetary disc. In this work we study the kinematic signatures of circumbinary discs in the residuals of their velocity maps. We show that Doppler-flips, spiral arms, eccentric gas motion, fast flows inside of the cavity, and vortex-like kinematic signatures are commonly observed. Unlike in the planetary mass companion case, Doppler-flips in circumbinary discs are not necessarily centred on a companion, and can extend towards the cavity edge. We then compare the kinematic signatures in our simulations with observations and see similarities to the Doppler-flip signal in HD 100546 and the vortex-like kinematic signatures in HD 142527. Our analysis also reveals kinematic evidence for binarity in several protoplantary disks typically regarded as circumstellar rather than circumbinary, including AB Aurigae and HD 100546.

Three-dimensional shear-wave velocity structure of the Adana–Iskenderun basins by ambient noise tomography

SUMMARY We construct a 3-D shear-wave velocity model for the crustal structure and the geometry of the Adana and Iskenderun basins by using ambient noise tomography of Rayleigh waves. For this purpose, we compute interstation Green's functions and measure the group velocity dispersion in the period range of 8–25 s. Then Rayleigh wave group velocity maps obtained by tomographic inversion are used to derive a shear wave velocity model by linearized inversion. Both Rayleigh wave group velocity maps and the 3-D shear-wave velocity structure are correlated with the geology and the major tectonic features of the region. Cross sections taken from the velocity model suggest a sediment thickness of up to 11 km in the wedge-shaped Adana Basin with the velocity ranging between 2.4 and 2.9 km s−1. The horseshoe-like high velocities surrounding the basin correspond to the Taurus Mountains in the west and north, and the Amanos Mountains in the east. In the region, down to a depth of 35 km the crustal velocity varies between 2.9 and 3.7 km s−1. Our investigations reveal the detailed 3-D basin geometry and crustal structure that can be beneficial for hazard assessment, geodynamic modelling as well as hydrocarbon exploration studies.

Droplet size, spray structure and droplet velocity mapping in hollow cone sprays using SLIPI-based techniques

The Structured Laser Illumination Planar Imaging (SLIPI) technique received significant attention in recent years due to notable improvements in the measurement of droplet size and the visualization of internal structure in both dilute and dense sprays. However, despite the improvements, the technique remains limited to these microscopic characteristics of the spray, primarily due to the complexity of the optical setup and image acquisition process. In this article, the capabilities of the SLIPI application are exploited, specifically employing the 3p-SLIPI-LIF/Mie (SLSD), and combined application of 1p-SLIPI-LIF & PIV (1p-SLIPI-PIV) for mapping of both Sauter Mean Diameter (SMD) and mean droplet velocity in combination with detailed spray structure analysis. The measurements were carried out in hollow cone sprays operated at the range of injection pressures from 25 to 107 bar. The results obtained using the SLIPI techniques were compared with the Phase Doppler Anemometry (PDA) measurements showing good agreement for both the SMD and mean droplet velocity. The significant improvements in the important microscopic characteristics (droplet size & velocity) and visualization of the internal structure in a wider flow field of hollow cone sprays allowed detailed analysis and understanding of the dispersed phase flow owing to the suppression of diffused light resulting from the multiple scattering effects.

Imaging Spin-Orbit Excitation of Yttrium through High-Energy Collisions with Rare Gas Atoms.

The energy required for spin-orbit excitation plays a critical role in understanding translational-to-electronic energy conversion, particularly in chemical reactions involving changes in spin states. This is particularly important for transition metal atoms possessing d-orbitals, which result in multiple spin-orbit split energy levels at low energies. The accurate identification and characterization of spin-orbit transitions in such species require advanced experimental techniques and theoretical support. In this study, the spin-orbit excited collisions of Y(2D3/2) with rare gas atoms Ne, Ar, and Kr leading to Y(2D5/2) were observed using laser-ablated crossed-beam and time-sliced ion velocity mapping imaging techniques. Through a comparison of the forward angular distributions of Y(2D3/2) to the backward and sideway scattering distributions of Y(2D5/2) from elastic and inelastic collisions of Y(2D) with rare gas atoms, this study reveals that the spin-orbit electronic excitation occurs with high collision energy and low impact parameters from backward and sideway collisions. The effectiveness of the spin-orbit excitation process is strongly dependent on the collision energy or temperature, suggesting that energy requirements of the process have to be considered in chemical reactions involving changes in spin states.

Structure of the crust and upper mantle in Greenland and northeastern Canada: Insights from anisotropic rayleigh-wave tomography

Summary Seismic velocity models provide important constraints on Greenland’s deep structure, which, in turn, has profound implications for our understanding of the tectonic history of this region. However, the resolution of seismic models has been limited by a sparse network, particularly in northern and central Greenland. We address these limitations by generating new high-resolution Rayleigh-wave phase velocity maps encompassing Greenland and northeastern Canada by processing over three decades of teleseismic earthquake records and incorporating recently added stations in Greenland and Arctic Canada. These phase velocity maps are sensitive to structure from the lower crust down to the sub-lithospheric mantle (25-185 s period). We find significant heterogeneity and a strong correlation between isotropic and anisotropic seismic velocities with inferred geological structure. High seismic velocities associated with cratonic lithosphere are broadly divided into two regions, with a belt of reduced velocity spanning central Greenland, which we interpret as lithospheric erosion resulting from interaction between the Greenland continental keel and the Iceland plume. Within each region, we identify tectonic subdivisions that suggest fundamental differences between the blocks that make up Precambrian Greenland. In the south, the North Atlantic craton (NAC) has a high-velocity keel exhibiting anisotropic stratification. Between the NAC and the cratonic lithosphere further north, the Proterozoic Nagssugtoqidian orogenic belt shows a distinct signature of reduced seismic velocity to ∼75 s period, but then appears to pinch out at depth. The northern Greenland lithosphere exhibits significant isotropic heterogeneity, with a distinct core of high velocities in the northwest (∼55-75 s period) giving way to a set of distinct east-west trending high-velocity belts at longer periods. At all periods sensitive to the lithospheric mantle in this region, anisotropic fast orientations are E-W, consistent with a north-south Precambrian assembly of the Greenland shield. In contrast to the NAC, there is no evidence of anisotropic stratification in the northern part of the cratonic keel. Based on both isotropic and anisotropic phase-velocity anomalies, we suggest that the Phanerozoic Caledonian and Ellesmerian-Franklinian fold belts are relatively thin-skinned features onshore Greenland, though the Caledonian belt may have a stronger signature off the east coast. At the longest periods, a prominent low-velocity anomaly initially centred on Iceland migrates northwards and spreads beneath central-eastern Greenland. Coupled with NW-SE trending anisotropy, this feature is interpreted as the effect of mantle flow radiating outward from the Iceland plume and interacting with the eroded Greenland lithosphere.

Hydrous Melting and its Seismic Signature

Hydrogen is known to affect elastic and anelastic properties of mantle rocks and minerals. Hydrogen dissolution in minerals notably alters the properties of transition zone phases, which may accommodate very high water contents. Moreover, even small amounts of water can induce partial melting in certain mantle regions and modify seismic wave velocities and attenuation. Progress in seismic imaging of the mantle—particularly the mapping of seismic attenuation and velocities—has improved constraints on local hydrous melt content in the upper mantle, and evidence exists for partial melt–bearing layers above and below the transition zone owing to dehydration reactions induced by upward or downward flow of mantle material. Further observational and modeling studies are needed to more fully understand the influence of hydrous melting on the global water cycle, mantle viscosity, and large-scale geodynamics.

Stellar angular momentum of intermediate-redshift galaxies in MUSE surveys

We quantify the stellar rotation of galaxies by computing the λR parameter, a proxy for the stellar angular momentum in a sample of 106 intermediate-redshift galaxies (0.1 < z < 0.8). The sample is located in the CANDELS/GOODS-S and CANDELS/COSMOS regions, and it was observed by various MUSE surveys. We created spatially resolved stellar velocity and velocity dispersion maps using a full-spectrum fitting technique, covering spatially ∼2Re for the galaxies. The sample spans stellar masses from ∼107.5 M⊙ to 1011.8 M⊙ with star formation rates (SFRs) from log10(SFR)≈ − 3 M⊙ yr−1 to ≈1.7 M⊙ yr−1 over a range of 6 Gyr in cosmic time. We studied how the atmospheric seeing, introduced by the instrumental point spread function (PSF), affects the measured spin parameter, and we applied corrections when pertinent. Through the analysis of the λR − ϵ diagram, we note that the fraction of round and massive galaxies increases with redshift. We did not measure any galaxy with λR < 0.1 in the sample, and we found only one potential (but uncertain) low-mass slow rotator at z ∼ 0.3, more similar to the z = 0 low-mass slow rotators characterized by counter-rotation than to massive ellipticals. Moreover, we do not see an evident evolution or trend in the stellar angular momentum with redshift. We characterized the galaxy environment using two different indicators: a local estimator based on the Voronoi tesselation method, and a global estimator derived by the use of the friends-of-friends (FoF) algorithm. We find no correlation between the environment and λR given that we are not probing dense regions or massive galaxy structures. We also analysed the kinematic maps of the sample finding that about 40% of the galaxies are consistent with being regular rotators (RRs), having rotating stellar discs with flat velocity dispersion maps, while ∼20% have complex velocity maps and can be identified as non-regular rotators in spite of their λR values. For the remaining galaxies the classification is uncertain. As we lack galaxies with λR < 0.1 in the sample, we are not able to identify when galaxies lose their angular momentum and become slow rotators within the surveyed environments, area, and redshift range.

KRATOS: A large suite of N-body simulations to interpret the stellar kinematics of LMC-like discs

Context. The Large and Small Magellanic Clouds (LMC and SMC, respectively) are the brightest satellites of the Milky Way (MW), and for the last thousand million years they have been interacting with one another. As observations only provide a static picture of the entire process, numerical simulations are used to interpret the present-day observational properties of these kinds of systems, and most of them have been focused on attempting to recreate the neutral gas distribution and characteristics through hydrodynamical simulations. Aims. We present KRATOS, a comprehensive suite of 28 open-access pure N-body simulations of isolated and interacting LMC-like galaxies designed for studying the formation of substructures in their discs after interaction with an SMC-mass galaxy. The primary objective of this paper is to provide theoretical models that help us to interpret the formation of general structures in an LMC-like galaxy under various tidal interaction scenarios. This is the first paper of a series dedicated to the analysis of this complex interaction. Methods. Simulations are grouped into 11 sets of up to three configurations, with each set containing (1) a control model of an isolated LMC-like galaxy; (2) a model that contains the interaction with an SMC-mass galaxy, and (3) a model where both an SMC-mass and a MW-mass galaxy may interact with the LMC-like galaxy (the most realistic model). In each simulation, we analysed the orbital history between the three galaxies and examined the morphological and kinematic features of the LMC-like disc galaxy throughout the interaction. This includes investigating the disc scale height and velocity maps. When a bar was found to develop, we characterised its strength, length, off-centredness, and pattern speed. Results. The diverse outcomes found in the KRATOS simulations, including the presence of bars, warped discs, and various spiral arm shapes, demonstrate the opportunities they offer to explore a range of LMC-like galaxy morphologies. These morphologies directly correspond to distinct disc kinematic maps, making them well-suited for a first-order interpretation of the LMC’s kinematic maps. From the simulations, we note that tidal interactions can: boost the disc scale height; both destroy and create bars; and naturally explain the off-centre stellar bars. The bar length and pattern speed of long-lived bars are not appreciably altered by the interaction. Conclusions. The high spatial, temporal, and mass resolution used in the KRATOS simulations has been shown to be appropriate for the purpose of interpreting the internal kinematics of LMC-like discs, as evidenced by the first scientific results presented in this work.

Towards chemical source tracking and characterization using physics-informed neural networks

This paper presents a new algorithm using physics-informed neural networks (PINNs) to track and characterize spatio-temporally varying chemical sources based on time-resolved measurements of chemical concentration, fluid velocity, and pressure. Chemical source emission functions, chemical concentration, fluid velocity and fluid pressure fields are modeled as multi-layer perceptrons (MLPs). During the training process, sensors readings of chemical concentration, fluid velocity, and fluid pressure are matched to the output of the respective MLPs at the given spatio-temporal locations. Simultaneously, the physics of fluid flow and chemical dispersion at an arbitrary number of spatio-temporal locations in the domain of interest are enforced through regularization. Once trained, the constituent MLPs can be evaluated to generate the time resolved maps of source emissions, chemical concentration, fluid velocity and pressure. Extensive numerical simulation validate the method, including scenarios with both static and dynamic sources in complex flow fields. This innovative approach marks a significant advancement in environmental monitoring technologies.