scholarly journals 3D1D hydro-nucleosynthesis simulations – I. Advective–reactive post-processing method and its application to H ingestion into He-shell flash convection in rapidly accreting white dwarfs

2021 ◽  
Vol 504 (1) ◽  
pp. 744-760 ◽  
Author(s):  
David Stephens ◽  
Falk Herwig ◽  
Paul Woodward ◽  
Pavel Denissenkov ◽  
Robert Andrassy ◽  
...  
Keyword(s):  
Mixing Model ◽  
Post Processing ◽  
Abundance Distribution ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
Energy Feedback ◽  
Mixing Coefficients ◽  
The Difference ◽  
Advective Mixing ◽  
Stream Model

ABSTRACT We present two mixing models for post-processing of 3D hydrodynamic simulations applied to convective–reactive i-process nucleosynthesis in a rapidly accreting white dwarf (RAWD) with [Fe/H] = −2.6, in which H is ingested into a convective He shell. A 1D advective two-stream model adopts physically motivated radial and horizontal mixing coefficients constrained by 3D hydrodynamic simulations. A simpler approach uses diffusion coefficients calculated from the same simulations. All 3D simulations include the energy feedback of the 12C(p, γ)13N reaction from the H entrainment. Global oscillations of shell H ingestion in two of the RAWD simulations cause bursts of entrainment of H and non-radial hydrodynamic feedback. With the same nuclear network as in the 3D simulations, the 1D advective two-stream model reproduces the rate and location of the H burning within the He shell closely matching the 3D simulation predictions, as well as qualitatively displaying the asymmetry of the XH profiles between the upstream and downstream. With a full i-process network the advective mixing model captures the difference in the n-capture nucleosynthesis in the upstream and downstream. For example, 89Kr and 90Kr with half-lives of $3.18\,\,\mathrm{\mathrm{min}}$ and $32.3\,\,\mathrm{\mathrm{s}}$ differ by a factor 2–10 in the two streams. In this particular application the diffusion approach provides globally the same abundance distribution as the advective two-stream mixing model. The resulting i-process yields are in excellent agreement with observations of the exemplary CEMP-r/s star CS31062-050.

scholarly journals Comparison of 2D and 3D compressible convection in a pre-main sequence star

2020 ◽  
Vol 638 ◽  
pp. A15
Author(s):  
J. Pratt ◽  
I. Baraffe ◽  
T. Goffrey ◽  
C. Geroux ◽  
T. Constantino ◽  
...  
Keyword(s):  
Penetration Depth ◽  
Stellar Evolution ◽  
Main Sequence ◽  
Convection Zone ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
Stellar Convection ◽  
The Difference ◽  
Set Up ◽  
2D And 3D

Context. A 1D description of stellar dynamics is at the basis of stellar evolution modeling. Designed to investigate open problems in stellar evolution, the MUltidimensional Stellar Implicit Code expands a realistic 1D profile of a star’s internal structure to examine the interior dynamics of a specific star through either 2D or 3D hydrodynamic simulations. Aims. Extending our recent studies of 2D stellar convection to 3D stellar convection, we aim to compare 3D hydrodynamic simulations to identically set-up 2D simulations, for a realistic pre-main sequence star. Methods. We compare statistical quantities related to convective flows including: average velocity, vorticity, local enstrophy, and penetration depth beneath a convection zone. These statistics were produced during stationary, steady-state compressible convection in the star’s convection zone. Results. Our simulations confirm the common result that 2D simulations of stellar convection have a higher magnitude of velocity on average than 3D simulations. Boundary conditions and the extent of the spherical shell can affect the magnitude and variability of convective velocities. The difference between 2D and 3D velocities is dependent on these background points; in our simulations this can have an effect as large as the difference resulting from the dimensionality of the simulation. Nevertheless, radial velocities near the convective boundary are comparable in our 2D and 3D simulations. The average local enstrophy of the flow is lower for 2D simulations than for 3D simulations, indicating a different shape and structuring of 3D stellar convection. We performed a statistical analysis of the depth of convective penetration below the convection zone using the model proposed in our recent study (Pratt et al. 2017, A&A, 604, A125). That statistical model was developed based on 2D simulations, which allowed us to examine longer times and higher radial resolution than are possible in 3D. Here, we analyze the convective penetration in 3D simulations, and compare the results to identically set-up 2D simulations. In 3D simulations, the penetration depth is as large as the penetration depth calculated from 2D simulations.

A Modified CGM Algorithm Enhances Data Availability While Retaining iCGM Performance

2021 ◽  
pp. 193229682110075
Author(s):  
Rebecca A. Harvey Towers ◽  
Xiaohe Zhang ◽  
Rasoul Yousefi ◽  
Ghazaleh Esmaili ◽  
Liang Wang ◽  
...  
Keyword(s):  
Data Integration ◽  
Patient Experience ◽  
Real World ◽  
Data Availability ◽  
Post Processing ◽  
Sensor Error ◽  
The Mean ◽  
The Difference ◽  
Data Gap ◽  
Improve Patient

The algorithm for the Dexcom G6 CGM System was enhanced to retain accuracy while reducing the frequency and duration of sensor error. The new algorithm was evaluated by post-processing raw signals collected from G6 pivotal trials (NCT02880267) and by assessing the difference in data availability after a limited, real-world launch. Accuracy was comparable with the new algorithm—the overall %20/20 was 91.7% before and 91.8% after the algorithm modification; MARD was unchanged. The mean data gap due to sensor error nearly halved and total time spent in sensor error decreased by 59%. A limited field launch showed similar results, with a 43% decrease in total time spent in sensor error. Increased data availability may improve patient experience and CGM data integration into insulin delivery systems.

Experimental Investigation During Stall and Surge in a Transonic Fan Stage and Rotor-Only Configuration

2006 ◽  
Author(s):  
A. J. Gannon ◽  
G. V. Hobson ◽  
R. P. Shreeve ◽  
I. J. Villescas
Keyword(s):  
High Speed ◽  
Fast Response ◽  
Pressure Measurements ◽  
Post Processing ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
The Difference ◽  
Data Signal ◽  
Transonic Fan ◽  
Casing Pressure

High-speed pressure measurements of a transonic compressor rotor-stator stage and rotor-only configuration during stall and surge are presented. Rotational speed data showed the difference between the rotor-only case and rotor-stator stage. The rotor-only case stalled and remained stalled until the control throttle was opened. In the rotor-stator stage the compressor surged entering a cyclical stalling and then un-stalling pattern. An array of pressure probes was mounted in the case wall over the rotor for both configurations of the machine. The fast response probes were sampled at 196 608 Hz as the rotor was driven into stall. Inspection of the raw data signal allowed the size and speed of the stall cell during its growth to be investigated. Post-processing of the simultaneous signals of the casing pressure showed the development of the stall cell from the point of inception and allowed the structure of the stall cell to be viewed.

scholarly journals Development of Urban Driving Cycle with GPS Data Post Processing

2016 ◽  
Vol 28 (4) ◽  
pp. 353-364 ◽  
Author(s):  
Peter Lipar ◽  
Irena Strnad ◽  
Martin Česnik ◽  
Tomaž Maher
Keyword(s):  
Data Collection ◽  
Urban Area ◽  
Measurement Data ◽  
Driving Cycle ◽  
Gps Data ◽  
Post Processing ◽  
The Difference ◽  
Large Random Sample ◽  
Representative Area ◽  
Development Methods

This paper presents GIS-based methodology for urban area driving cycle construction. The approach reaches beyond the frames of usual driving cycle development methods and takes into account another perspective of data collection. Rather than planning data collection, the approach is based on available in-vehicle measurement data post processing using Geographic Information Systems to manipulate the excessive database and extract only the representative and geographically limited individual trip data. With such data post processing the data was carefully adjusted to include only the data that describe representative driving in Ljubljana urban area. The selected method for the driving cycle development is based on searching for the best microtrips combination while minimizing the difference between two vectors; one based on generated cycle and the other on the database. Accounting for a large random sample of actual trip data, our approach enables more representative area-specific driving cycle development than the previously used techniques.

scholarly journals Observable scattered light features from inclined and non-inclined planets embedded in protoplanetary discs

2019 ◽  
Vol 487 (4) ◽  
pp. 5372-5387
Author(s):  
Dylan L Kloster ◽  
M Flock
Keyword(s):  
Surface Density ◽  
Scattered Light ◽  
Intensity Variation ◽  
Theoretical Models ◽  
Upper Atmosphere ◽  
High Mass ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
2D And 3D ◽  
Protoplanetary Discs

ABSTRACT Over the last few years instruments such as VLT/SPHERE and Subaru/HiCIAO have been able to take detailed scattered light images of protoplanetary discs. Many of the features observed in these discs are generally suspected to be caused by an embedded planet, and understanding the cause of these features requires detailed theoretical models. In this work we investigate disc–planet interactions using the pluto code to run 2D and 3D hydrodynamic simulations of protoplanetary discs with embedded 30 and 300 M⊕ planets on both an inclined (i = 2.86°) and non-inclined orbit, using an α-viscosity of 4 × 10−3. We produce synthetic scattered light images of these discs at H-band wavelengths using the radiative transfer code radmc3d. We find that while the surface density evolution in 2D and 3D simulations of inclined and non-inclined planets remain fairly similar, their observational appearance is remarkably different. Most of the features seen in the synthetic H-band images are connected to density variations of the disc at around 3.3 scale heights above and below the mid-plane, which emphasizes the need for 3D simulations. Planets on sustained orbital inclinations disrupt the disc’s upper atmosphere and produce radically different observable features and intensity profiles, including shadowing effects and intensity variation of the order of 10–20 times the surrounding background. The vertical optical depth to the disc mid-plane for H-band wavelengths is τ ≈ 20 in the disc gap created by the high-mass planet. We conclude that direct imaging of planets embedded in the disc remains difficult to observe, even for massive planets in the gap.

scholarly journals Radiation-driven Feedback to the ISM around AGNs

2012 ◽  
Vol 8 (S292) ◽  
pp. 357-362
Author(s):  
Keiichi Wada
Keyword(s):  
Accretion Rate ◽  
Turbulent Motion ◽  
Hydrodynamic Simulations ◽  
Average Mass ◽  
Energy Feedback ◽  
Wide Range ◽  
Stellar Energy ◽  
Plausible Mechanism ◽  
Central Parsec

AbstractAlthough the “donut-like” obscuring molecular torus is often postulated to explain the type-1 and -2 dichotomy in AGNs, its physical origin is still unclear. We propose a plausible mechanism to explain the formation of the geometrically and optically thick torus, i.e. radiation-driven fountain. Using 3-D hydrodynamic simulations including radiative feedback from the central source, taking into account the X-ray heating and radiation pressure on the gas, we found that a vertical circulation of gas is generated in the central few to tens parsecs. Interaction between the non-steady outflows and inflows causes the formation of a geometrically thick torus with internal turbulent motion. As a result, the AGN is obscured for a wide range of solid angles. In a quasi-steady state, the opening angles for the column density toward a black hole < 1023 cm−2 are approximately ± 30° and ± 50° for AGNs with 10% and 1% Eddington luminosity, respectively. Mass inflows through the torus coexist with the outflow and internal turbulent motion, although the average mass accretion rate to the central parsec region is about ten times smaller than the accretion rate required to maintain the assumed AGN luminosity. This implies that relatively luminous AGN activity is intrinsically intermittent or that there are other mechanisms, such as stellar energy feedback, that enhance the mass accretion to the center.

scholarly journals ALMA observations of Molecules in Supernova 1987A

2017 ◽  
Vol 12 (S331) ◽  
pp. 294-299
Author(s):  
M. Matsuura ◽  
R. Indebetouw ◽  
S. Woosley ◽  
V. Bujarrabal ◽  
F. J. Abellán ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Line Profiles ◽  
Hydrodynamic Simulations ◽  
Sn 1987A ◽  
Theoretical Predictions ◽  
Solar Metallicity ◽  
The Difference ◽  
Si Isotope ◽  
First Time ◽  
Chemistry Dynamics

AbstractSupernova (SN) 1987A has provided a unique opportunity to study how SN ejecta evolve in 30 years time scale. We report our ALMA spectral observations of SN 1987A, taken in 2014, 2015 and 2016, with detections of CO, 28SiO, HCO+ and SO, with weaker lines of 29SiO.We find a dip in the SiO line profiles, suggesting that the ejecta morphology is likely elongated. The difference of the CO and SiO line profiles is consistent with hydrodynamic simulations, which show that Rayleigh-Taylor instabilities causes mixing of gas, with heavier elements much more disturbed, making more elongated structure.Using 28SiO and its isotopologues, Si isotope ratios were estimated for the first time in SN 1987A. The estimated ratios appear to be consistent with theoretical predictions of inefficient formation of neutron rich atoms at lower metallicity, such as observed in the Large Magellanic Cloud (about half a solar metallicity).The deduced large HCO+ mass and small SiS mass, which are inconsistent to the predictions of chemical model, might be explained by some mixing of elements immediately after the explosion. The mixing might have made some hydrogen from the envelope to sink into carbon and oxygen-rich zone during early days after the explosion, enabling the formation of a substantial mass of HCO+. Oxygen atoms may penetrate into silicon and sulphur zone, suppressing formation of SiS.Our ALMA observations open up a new window to investigate chemistry, dynamics and explosive-nucleosynthesis in supernovae.

scholarly journals Meridional Circulation of Dust and Gas in the Circumstellar Disk: Delivery of Solids onto the Circumplanetary Region

2022 ◽  
Vol 924 (1) ◽  
pp. 1
Author(s):  
J. Szulágyi ◽  
F. Binkert ◽  
C. Surville
Keyword(s):  
Meridional Circulation ◽  
Circumstellar Disk ◽  
Hydrodynamic Simulations ◽  
Planetary Mass ◽  
Accretion Rates ◽  
The Difference ◽  
Local Dust ◽  
Gas Accretion ◽  
The Hill ◽  
Gas Ratio

Abstract We carried out 3D dust + gas radiative hydrodynamic simulations of forming planets. We investigated a parameter grid of a Neptune-mass, a Saturn-mass, a Jupiter-mass, and a five-Jupiter-mass planet at 5.2, 30, and 50 au distance from their star. We found that the meridional circulation (Szulágyi et al. 2014; Fung & Chiang 2016) drives a strong vertical flow for the dust as well, hence the dust is not settled in the midplane, even for millimeter-sized grains. The meridional circulation will deliver dust and gas vertically onto the circumplanetary region, efficiently bridging over the gap. The Hill-sphere accretion rates for the dust are ∼10−8–10−10 M Jup yr−1, increasing with planet mass. For the gas component, the gain is 10−6–10−8 M Jup yr−1. The difference between the dust and gas-accretion rates is smaller with decreasing planetary mass. In the vicinity of the planet, the millimeter-sized grains can get trapped easier than the gas, which means the circumplanetary disk might be enriched with solids in comparison to the circumstellar disk. We calculated the local dust-to-gas ratio (DTG) everywhere in the circumstellar disk and identified the altitude above the midplane where the DTG is 1, 0.1, 0.01, and 0.001. The larger the planetary mass, the more the millimeter-sized dust is delivered and a larger fraction of the dust disk is lifted by the planet. The stirring of millimeter-sized dust is negligible for Neptune-mass planets or below, but significant above Saturn-mass planets.

scholarly journals REKONSTRUKSI BATAS BIDANG TANAH MENGGUNAKAN JARINGAN REFERENSI SATELIT PERTANAHAN

2018 ◽  
Vol 1 (1) ◽  
pp. 99-112
Author(s):  
Kariyono Kariyono ◽  
Eko Budi Wahyono ◽  
Tanjung Nugroho
Keyword(s):  
Real Time ◽  
Lateral Displacement ◽  
T Test ◽  
A Posteriori ◽  
Post Processing ◽  
Coordinate Transfer ◽  
The Difference ◽  
Transfer Method ◽  
Level Of Significance

Abstract: ORS is a GNSS station operating continuously for 24 hours. It is also used as a reference for determining a, both asa real time and as post-processing. Cors in BPN RI is known as Jaringan Referensi Satelit Pertanahan (JRSP). BPN RI has notyet optimized the use JRSP to reconstruct parcel boundaries. The research is aimed at examine the JRSP in reconstructingparcel boundaries. The analysis on lateral displacement tolerance and the difference on the area of parcles was based ontechnical guidance of PMNA/KBPN No. 3 of 1997 and the t test using the level of significance of ( )=5%. The resultswere:1)The reconstruction of parcels using JSRP can be done by firstly implementing the coordinate transfer and the mostaccurate Helmert coordinate transfer method using a posteriori variance of ( ) = 1.143020313; 2) The lateral transformationand the difference on parcel areas using JRSP suited the tolerance and the result of the t test did not show anysignificance level of ( ) = 5% .Keywords: reconstruction, parcel boundaries, JRSPAbstrak: CORS merupakan stasiun GNSS yang beroperasi secara kontinyu selama 24 jam sebagai acuan penentuan posisi, baiksecara real time maupun post-processing. CORS di BPN RI dikenal sebagai Jaringan Referensi Satelit Pertanahan (JRSP). BPN RIbelum mengoptimalkan pelaksanaan rekonstruksi batas bidang tanah menggunakan JRSP. Tujuan dalam penelitian ini adalahuntuk menguji JRSP dalam pelaksanaan rekonstruksi batas bidang tanah. Analisis terhadap toleransi pergeseran lateral danperbedaan luas bidang tanah hasil rekonstruksi batas bidang tanah menggunakan JRSP berdasarkan Juknis PMNA/KBPN No 3tahun 1997 dan uji t dengan taraf signifikansi ( )=5%. Hasil penelitian ini adalah : 1)Rekonstruksi batas bidang tanah tanahmenggunakan JRSP dapat di laksanakan dengan terlebih dahulu melaksanakan transformasi koordinat dan metode transformasikoordinat yang paling teliti adalah metode Helmert dengan varian posteriori ( ) = 1.143020313; 2)Pergeseran lateral danperbedaan luas bidang tanah hasil rekonstruksi batas bidang tanah menggunakan JRSP memenuhi syarat toleransi dan dari uji tdengan taraf signifikansi ( ) = 5% tidak terdapat perbedaan yang signifikan.Kata Kunci: Rekonstruksi, Batas Bidang Tanah , JRSP

scholarly journals Analysis of microscopic properties of radiative shock experiments performed at the Orion laser facility

2018 ◽  
Vol 6 ◽  
Author(s):  
R. Rodríguez ◽  
G. Espinosa ◽  
J. M. Gil ◽  
F. Suzuki-Vidal ◽  
T. Clayson ◽  
...  
Keyword(s):  
Spectroscopic Properties ◽  
Radiation Hydrodynamics ◽  
Post Processing ◽  
Radiative Shock ◽  
Hydrodynamic Simulations ◽  
Shock Region ◽  
Laser Facility ◽  
Post Shock ◽  
Charge State Distributions ◽  
Thermodynamic Regime

In this work we have conducted a study on the radiative and spectroscopic properties of the radiative precursor and the post-shock region from experiments with radiative shocks in xenon performed at the Orion laser facility. The study is based on post-processing of radiation-hydrodynamics simulations of the experiment. In particular, we have analyzed the thermodynamic regime of the plasma, the charge state distributions, the monochromatic opacities and emissivities, and the specific intensities for plasma conditions of both regions. The study of the intensities is a useful tool to estimate ranges of electron temperatures present in the xenon plasma in these experiments and the analysis performed of the microscopic properties commented above helps to better understand the intensity spectra. Finally, a theoretical analysis of the possibility of the onset of isobaric thermal instabilities in the post-shock has been made, concluding that the instabilities obtained in the radiative-hydrodynamic simulations could be thermal ones due to strong radiative cooling.

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