scholarly journals Jovian Electrons In The Inner Heliosphere: A Parameter Study On Intensity Profiles Near Earth

2016 ◽  
Author(s):  
Adrian Vogt ◽  
Phillip Dunzlaff ◽  
Bernd Heber ◽  
Andreas Kopp ◽  
Patrick Kuehl ◽  
...  
Keyword(s):  
Parameter Study ◽  
Jovian Electrons ◽  
Inner Heliosphere

scholarly journals The residence-time of Jovian electrons in the inner heliosphere

2020 ◽  
Vol 642 ◽  
pp. A170
Author(s):  
A. Vogt ◽  
N. E. Engelbrecht ◽  
R. D. Strauss ◽  
B. Heber ◽  
A. Kopp ◽  
...  
Keyword(s):  
Residence Time ◽  
Propagation Model ◽  
Model Parameters ◽  
Propagation Time ◽  
Transport Parameters ◽  
Jovian Magnetosphere ◽  
In Situ Observations ◽  
Jovian Electrons ◽  
Inner Heliosphere

Context. Jovian electrons serve an important role in test-particle distribution in the inner heliosphere. They have been used extensively in the past to study the (diffusive) transport of cosmic rays in the inner heliosphere. With new limits on the Jovian source function, that is, the particle intensity just outside the Jovian magnetosphere, and a new set of in-situ observations at 1 AU for cases of both good and poor magnetic connection between the source and observer, we revisit some of these earlier simulations. Aims. We aim to find the optimal numerical set-up that can be used to simulate the propagation of 6 MeV Jovian electrons in the inner heliosphere. Using such a setup, we further aim to study the residence (propagation) times of these particles for different levels of magnetic connection between Jupiter and an observer at Earth (1 AU). Methods. Using an advanced Jovian electron propagation model based on the stochastic differential equation approach, we calculated the Jovian electron intensity for different model parameters. A comparison with observations leads to an optimal numerical setup, which was then used to calculate the so-called residence (propagation) times of these particles. Results. Through a comparison with in-situ observations, we were able to derive transport parameters that are appropriate for the study of the propagation of 6 MeV Jovian electrons in the inner heliosphere. Moreover, using these values, we show that the method of calculating the residence time applied in the existing literature is not suited to being interpreted as the propagation time of physical particles. This is due to an incorrect weighting of the probability distribution. We applied a new method, where the results from each pseudo-particle are weighted by its resulting phase-space density (i.e. the number of physical particles that it represents). We thereby obtained more reliable estimates for the propagation time.

scholarly journals Theory of cosmic ray modulation

2008 ◽  
Vol 4 (S257) ◽  
pp. 429-438 ◽  
Author(s):  
Stefan E. S. Ferreira
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Cosmic Ray ◽  
Transport Parameters ◽  
Cosmic Ray Modulation ◽  
Field Lines ◽  
Jovian Electrons ◽  
Globally Distributed ◽  
The Magnetic Field ◽  
Inner Heliosphere

AbstractThis work aims to give a brief overview on the topic of cosmic ray modulation in the heliosphere. The heliosphere, heliospheric magnetic field, transport parameters and the transport equation together with modulation models, which solve this equation in various degree of complexity, are briefly discussed. Results from these models are then presented where first it is shown how cosmic rays are globally distributed in an asymmetrical heliosphere which results from the relative motion between the local interstellar medium and the Sun. Next the focus shifts to low-energy Jovian electrons. The intensities of these electrons, which originate from a point source in the inner heliosphere, exhibit a unique three-dimensional spiral structure where most of the particles are transported along the magnetic field lines. Time-dependent modulation is also discussed where it is shown how drift effects together with propagating diffusion barriers are responsible for modulation over a solar cycle.

scholarly journals Jovian electrons in the inner heliosphere

2018 ◽  
Vol 613 ◽  
pp. A28 ◽  
Author(s):  
A. Vogt ◽  
B. Heber ◽  
A. Kopp ◽  
M. S. Potgieter ◽  
R. D. Strauss
Keyword(s):  
Numerical Models ◽  
Transport Processes ◽  
Source Spectrum ◽  
Accurate Estimation ◽  
Jovian Magnetosphere ◽  
Test Particles ◽  
Charged Particle Transport ◽  
Jovian Electrons ◽  
Pioneer 10 ◽  
Inner Heliosphere

Context. Since the Pioneer 10 flyby of Jupiter it has become well known that electrons of Jovian origin dominate the lower MeV range of charged energetic particles in the inner heliosphere. Aims. Because the Jovian source can be treated as point-like in numerical models, many attempts to investigate charged particle transport in the inner heliosphere have utilized Jovian electrons as test particles. The reliability of the derived parameters for convective and diffusive transport processes are therefore highly dependent on an accurate estimation of the Jovian source spectrum. In this study we aim to provide such an estimation. Methods. In this study we have proposed a new electron source spectrum, specified at the boundary of the Jovian magnetosphere, fitted to flyby measurements by Pioneer 10 and Ulysses, with a spectral shape also in agreement with measurements at Earth’s orbit by Ulysses, Voyager 1, ISEE and SOHO. Results. The proposed spectrum is consistent with all previous theoretical suggestions, but deviates considerably in the lower MeV range which was inaccessible to those studies.

The buckling resistance of welded plate girders taking into account the influence of post-welding imperfections – Part 1: Parameter study

2017 ◽  
Vol 59 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Benjamin Launert ◽  
Radosław Szczerba ◽  
Marcin Gajewski ◽  
Michael Rhode ◽  
Hartmut Pasternak ◽  
...  
Keyword(s):  
Parameter Study ◽  
Plate Girders ◽  
Buckling Resistance

scholarly journals Mechanical Stability of Hybrid Corrugated Sandwich Plates under Fluid-Structure-Thermal Coupling for Novel Thermal Protection Systems

2020 ◽  
Vol 10 (8) ◽  
pp. 2790
Author(s):  
Wenzheng Zhuang ◽  
Chao Yang ◽  
Zhigang Wu
Keyword(s):  
Mechanical Stability ◽  
Thermal Protection ◽  
Element Model ◽  
Parameter Study ◽  
The Novel ◽  
Thermal Coupling ◽  
Mechanical Instability ◽  
Fluid Structure ◽  
Thermal Protection Systems ◽  
Protection Systems

Hybrid corrugated sandwich (HCS) plates have become a promising candidate for novel thermal protection systems (TPS) due to their multi-functionality of load bearing and thermal protection. For hypersonic vehicles, the novel TPS that performs some structural functions is a potential method of saving weight, which is significant in reducing expensive design/manufacture cost. Considering the novel TPS exposed to severe thermal and aerodynamic environments, the mechanical stability of the HCS plates under fluid-structure-thermal coupling is crucial for preliminary design of the TPS. In this paper, an innovative layerwise finite element model of the HCS plates is presented, and coupled fluid-structure-thermal analysis is performed with a parameter study. The proposed method is validated to be accurate and efficient against commercial software simulation. Results have shown that the mechanical instability of the HCS plates can be induced by fluid-structure coupling and further accelerated by thermal effect. The influences of geometric parameters on thermal buckling and dynamic stability present opposite tendencies, indicating a tradeoff is required for the TPS design. The present analytical model and numerical results provide design guidance in the practical application of the novel TPS.

scholarly journals Hugoniot Data and Equation of State Parameters for an Ultra-High Performance Concrete

2021 ◽  
Author(s):  
C. Sauer ◽  
F. Bagusat ◽  
M.-L. Ruiz-Ripoll ◽  
C. Roller ◽  
M. Sauer ◽  
...  
Keyword(s):  
Equation Of State ◽  
High Performance ◽  
High Performance Concrete ◽  
Applied Pressure ◽  
High Strength ◽  
Parameter Study ◽  
Ultra High Performance Concrete ◽  
Data Set ◽  
Shock Response ◽  
Particle Velocities

AbstractThis work aims at the characterization of a modern concrete material. For this purpose, we perform two experimental series of inverse planar plate impact (PPI) tests with the ultra-high performance concrete B4Q, using two different witness plate materials. Hugoniot data in the range of particle velocities from 180 to 840 m/s and stresses from 1.1 to 7.5 GPa is derived from both series. Within the experimental accuracy, they can be seen as one consistent data set. Moreover, we conduct corresponding numerical simulations and find a reasonably good agreement between simulated and experimentally obtained curves. From the simulated curves, we derive numerical Hugoniot results that serve as a homogenized, mean shock response of B4Q and add further consistency to the data set. Additionally, the comparison of simulated and experimentally determined results allows us to identify experimental outliers. Furthermore, we perform a parameter study which shows that a significant influence of the applied pressure dependent strength model on the derived equation of state (EOS) parameters is unlikely. In order to compare the current results to our own partially reevaluated previous work and selected recent results from literature, we use simulations to numerically extrapolate the Hugoniot results. Considering their inhomogeneous nature, a consistent picture emerges for the shock response of the discussed concrete and high-strength mortar materials. Hugoniot results from this and earlier work are presented for further comparisons. In addition, a full parameter set for B4Q, including validated EOS parameters, is provided for the application in simulations of impact and blast scenarios.

scholarly journals DESTINY: Database for the Effects of STellar encounters on dIsks and plaNetary sYstems

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Asmita Bhandare ◽  
Susanne Pfalzner
Keyword(s):  
Planetary System ◽  
Planetary Systems ◽  
Gravitational Effect ◽  
Parameter Study ◽  
Orbital Inclination ◽  
Particle Properties ◽  
Disk Size ◽  
Stellar Group ◽  
Cluster Environment ◽  
Parabolic Orbits

Abstract Most stars form as part of a stellar group. These young stars are mostly surrounded by a disk from which potentially a planetary system might form. Both, the disk and later on the planetary system, may be affected by the cluster environment due to close fly-bys. The here presented database can be used to determine the gravitational effect of such fly-bys on non-viscous disks and planetary systems. The database contains data for fly-by scenarios spanning mass ratios between the perturber and host star from 0.3 to 50.0, periastron distances from 30 au to 1000 au, orbital inclination from 0∘ to 180∘ and angle of periastron of 0∘, 45∘ and 90∘. Thus covering a wide parameter space relevant for fly-bys in stellar clusters. The data can either be downloaded to perform one’s own diagnostics like for e.g. determining disk size, disk mass, etc. after specific encounters, obtain parameter dependencies or the different particle properties can be visualized interactively. Currently the database is restricted to fly-bys on parabolic orbits, but it will be extended to hyperbolic orbits in the future. All of the data from this extensive parameter study is now publicly available as DESTINY.

scholarly journals Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1089
Author(s):  
Leonard Raumann ◽  
Jan Willem Coenen ◽  
Johann Riesch ◽  
Yiran Mao ◽  
Daniel Schwalenberg ◽  
...  
Keyword(s):  
Relative Density ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Process Time ◽  
Parameter Study ◽  
Reactor Model ◽  
Production Route ◽  
Coating Uniformity ◽  
Hydrogen Retention ◽  
Return Lead

Tungsten (W) has the unique combination of excellent thermal properties, low sputter yield, low hydrogen retention, and acceptable activation. Therefore, W is presently the main candidate for the first wall and armor material for future fusion devices. However, its intrinsic brittleness and its embrittlement during operation bears the risk of a sudden and catastrophic component failure. As a countermeasure, tungsten fiber-reinforced tungsten (Wf/W) composites exhibiting extrinsic toughening are being developed. A possible Wf/W production route is chemical vapor deposition (CVD) by reducing WF6 with H2 on heated W fabrics. The challenge here is that the growing CVD-W can seal gaseous domains leading to strength reducing pores. In previous work, CVD models for Wf/W synthesis were developed with COMSOL Multiphysics and validated experimentally. In the present article, these models were applied to conduct a parameter study to optimize the coating uniformity, the relative density, the WF6 demand, and the process time. A low temperature and a low total pressure increase the process time, but in return lead to very uniform W layers at the micro and macro scales and thus to an optimized relative density of the Wf/W composite. High H2 and low WF6 gas flow rates lead to a slightly shorter process time and an improved coating uniformity as long as WF6 is not depleted, which can be avoided by applying the presented reactor model.

scholarly journals An extensive parameter study of hydrotropic extraction of steam-pretreated birch

2021 ◽  
Author(s):  
Johanna Olsson ◽  
Michael Persson ◽  
Mats Galbe ◽  
Ola Wallberg ◽  
Ann-Sofi Jönsson
Keyword(s):  
Residence Time ◽  
Steam Explosion ◽  
Room Temperature ◽  
Initial Step ◽  
Parameter Study ◽  
Hydrothermal Degradation ◽  
Steam Explosion Pretreatment ◽  
Lignin Extraction ◽  
Extraction Step ◽  
Lignin Recovery

AbstractEfficient fractionation of lignocellulosic biomass is an important step toward the replacement of fossil-based products. However, the utilisation of all of the components in biomass requires various fractionation techniques. One promising process configuration is to apply steam explosion for the recovery of hemicelluloses and a subsequent hydrotropic extraction step for the delignification of the remaining solids. In this work, the influence of residence time, temperature and biomass loading on lignin recovery from birch using sodium xylene sulphonate as a hydrotrope was investigated. Our results show that residence time, temperature and biomass loading correlate positively with lignin extraction, but the effects of these parameters were limited. Furthermore, when steam explosion was implemented as the initial step, hydrotropic extraction could be performed even at room temperature, yielding a lignin extraction of 50%. Also, hydrothermal degradation of the material was necessary for efficient delignification with sodium xylene sulphonate, regardless of whether it occurs during steam explosion pretreatment or is achieved at high temperatures during the hydrotropic extraction.

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