model setup
Recently Published Documents


TOTAL DOCUMENTS

218
(FIVE YEARS 105)

H-INDEX

20
(FIVE YEARS 5)

2022 ◽  
Author(s):  
Justus Wöhl ◽  
Wassja Kopp ◽  
Iryna Yevlakhovych ◽  
Leo Bahr ◽  
Hans-Jürgen Koß ◽  
...  

The spectroscopic quantification of mixture compositions usually requires pure compounds and mixtures of known composition for calibration. Since they are not always available, methods to fill such gaps have evolved, which are, however, not generally applicable. Therefore, calibration can be extremely challenging, especially when multiple instable species, e.g. intermediates, exist in a system. This study presents a new calibration approach that uses ab initio Molecular Dynamics (AIMD)-simulated spectra as to set up and calibrate models for the physics-based spectral analysis method Indirect Hard Modeling (IHM). To demonstrate our approach called AIMD-IHM, we analyze Raman spectra of ternary hydrogen-bonding mixtures of acetone, methanol, and ethanol. The derived AIMD-IHM pure-component models and calibration coefficients are in good agreement with conventionally generated experimental results. The method yields compositions with prediction errors of less than 5% without any experimental calibration input. Our approach can be extended, in principle, to IR and NMR spectroscopy and allows for the analysis of systems that were hitherto inaccessible to quantitative spectroscopic analysis.


2021 ◽  
Author(s):  
Cara Nissen ◽  
Ralph Timmermann ◽  
Mario Hoppema ◽  
Judith Hauck

Abstract Antarctic Bottom Water formation, such as in the Weddell Sea, is an efficient vector for carbon sequestration on time scales of centuries. Possible changes in carbon sequestration under changing environmental conditions are unquantified to date, mainly due to difficulties in simulating the relevant processes on high-latitude continental shelves. Using a model setup including both ice-shelf cavities and oceanic carbon cycling, we demonstrate that by 2100, deep-ocean carbon accumulation in the southern Weddell Sea is abruptly attenuated to only 40% of the rate in the 1990s in a high-emission scenario, while still being 4-fold higher in the 2080s. Assessing deep-ocean carbon budgets and water mass transformations, we attribute this decline to an increased presence of Warm Deep Water on the southern Weddell Sea continental shelf, a 16% reduction in sea-ice formation, and a 79% increase in ice-shelf basal melt. Altogether, these changes lower the density and volume of newly formed bottom waters and reduce the associated carbon transport to the abyss.


2021 ◽  
Author(s):  
Sophie L. Norris ◽  
et al.

Description of laboratory techniques, age calculation, complication of preexisting chronology, and model setup.<br>


2021 ◽  
Author(s):  
Sophie L. Norris ◽  
et al.

Description of laboratory techniques, age calculation, complication of preexisting chronology, and model setup.<br>


Author(s):  
Aliaksei Patsekha ◽  
Robert Galler

AbstractThe “wind tunnel” approach is applied to study high-speed train aerodynamics in a railway tunnel using FDS software. The main focus of the research is on the pressure distribution along the tunnel. Proven analytical dependencies based on the experimental observations for air jet centerline velocity and flow entrainment are used to evaluate the model setup. A model verification is carried out based on the pressure drop calculations due to viscous effects where the impact of the surface roughness and the tunnel length are also considered. A sensitivity analysis is performed to evaluate changes in input FDS parameters and to explore interactions between them. It is proposed to use the standard deviation, obtained from the calculated time-averaged pressure values, to specify the appropriate numeric parameter combinations, e.g. DT and PRESSURE_TOLERANCE, considering the desired results consistency and the computational time consumed. The simulated cases with and without a train inside a tunnel provide data on the aerodynamic characteristics of the models. The obtained volumetric and cross-sectional profiles for pressure and airflow velocity distribution form the basis for an informed decision regarding the tunnel design or safety solutions, for example, defining areas under maximal and minimal pressure loads. The analysis displays the necessity to carefully manage each investigated case considering the FDS features and limitations that largely affect a model setup and calculations.


2021 ◽  
Author(s):  
Derek Neuharth ◽  
et al.

Description of the model setup (including governing and rheologic equations) and coupling between codes FastScape and ASPECT in more detail, and supplemental figures with additional information including mapviews of the New Guinea, Yinggehai, and Navassa Basins.<br>


2021 ◽  
Author(s):  
Derek Neuharth ◽  
et al.

Description of the model setup (including governing and rheologic equations) and coupling between codes FastScape and ASPECT in more detail, and supplemental figures with additional information including mapviews of the New Guinea, Yinggehai, and Navassa Basins.<br>


Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3071
Author(s):  
Pouya Sabokruhie ◽  
Eric Akomeah ◽  
Tammy Rosner ◽  
Karl-Erich Lindenschmidt

A quasi-two-dimensional (quasi-2D) modelling approach is introduced to mimic transverse mixing of an inflow into a river from one of its banks, either an industrial outfall or a tributary. The concentrations of determinands in the inflow vary greatly from those in the river, leading to very long mixing lengths in the river downstream of the inflow location. Ideally, a two-dimensional (2D) model would be used on a small scale to capture the mixing of the two flow streams. However, for large-scale applications of several hundreds of kilometres of river length, such an approach demands too many computational resources and too much computational time, especially if the application will at some point require ensemble input from climate-change scenario data. However, a one-dimensional (1D) model with variables varying in the longitudinal flow direction but averaged across the cross-sections is too simple of an approach to capture the lateral mixing between different flow streams within the river. Hence, a quasi-2D method is proposed in which a simplified 1D solver is still applied but the discretisation of the model setup can be carried out in such a way as to enable a 2D representation of the model domain. The quasi-2D model setup also allows secondary channels and side lakes in floodplains to be incorporated into the discretisation. To show proof-of-concept, the approach has been tested on a stretch of the lower Athabasca River in Canada flowing through the oil sands region between Fort McMurray and Fort MacKay. A dye tracer and suspended sediments are the constituents modelled in this test case.


2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Thomas G. Rizzo

Abstract If dark matter (DM) interacts with the Standard Model (SM) via the kinetic mixing (KM) portal, it necessitates the existence of portal matter (PM) particles which carry both dark and SM quantum numbers that will appear in vacuum polarization-like loop graphs. In addition to the familiar ∼ eϵQ strength, QED-like interaction for the dark photon (DP), in some setups different loop graphs of these PM states can also induce other coupling structures for the SM fermions that may come to dominate in at least some regions of parameter space regions and which can take the form of ‘dark’ moments, e.g., magnetic dipole-type interactions in the IR, associated with a large mass scale, Λ. In this paper, motivated by a simple toy model, we perform a phenomenological investigation of a possible loop-induced dark magnetic dipole moment for SM fermions, in particular, for the electron. We show that at the phenomenological level such a scenario can not only be made compatible with existing experimental constraints for a significant range of correlated values for Λ and the dark U(1)D gauge coupling, gD, but can also lead to quantitatively different signatures once the DP is discovered. In this setup, assuming complex scalar DM to satisfy CMB constraints, parameter space regions where the DP decays invisibly are found to be somewhat preferred if PM mass limits from direct searches at the LHC and our toy model setup are all taken seriously. High precision searches for, or measurements of, the e+e− → γ + DP process at Belle II are shown to provide some of the strongest future constraints on this scenario.


Sign in / Sign up

Export Citation Format

Share Document