scholarly journals Visualization of the Anisotropy of the Velocity Dispersion and Characteristics of the Multi-Velocity Continuum in the Regions of Multi-Stream Flows of Gas-Dust Media with Polydisperse Dust

2020 ◽  
Vol 6 (9) ◽  
pp. 98
Author(s):  
Mikhail A. Bezborodov ◽  
Mikhail A. Eremin ◽  
Vitaly V. Korolev ◽  
Ilya G. Kovalenko ◽  
Elena V. Zhukova
Keyword(s):  
Stream Flow ◽  
Velocity Dispersion ◽  
Scalar Fields ◽  
Velocity Fields ◽  
Velocity Space ◽  
Coordinate Space ◽  
Tensor Fields ◽  
Color Representation ◽  
Dispersion Tensor ◽  
First Case

Collisionless media devoid of intrinsic stresses, for example, a dispersed phase in a multiphase medium, have a much wider variety of space-time structures and features formed in them than collisional media, for example, a carrier, gas, or liquid phase. This is a consequence of the fact that evolution in such media occurs in phase space, i.e., in a space of greater dimensions than the usual coordinate space. As a consequence, the process of the formation of features in collisionless media (clustering or vice versa, a loss of continuity) can occur primarily in the velocity space, which, in contrast to the features in the coordinate space (folds, caustics, or voids), is poorly observed directly. To identify such features, it is necessary to use visualization methods that allow us to consider, in detail, the evolution of the medium in the velocity space. This article is devoted to the development of techniques that allow visualizing the degree of anisotropy of the velocity fields of collisionless interpenetrating media. Simultaneously tracking the behavior of different fractions in such media is important, as their behavior can be significantly different. We propose three different techniques for visualizing the anisotropy of velocity fields using the example of two- and three-continuum dispersed media models. We proposed the construction of spatial distributions of eccentricity fields (scalar fields), or fields of principal directions of the velocity dispersion tensor (tensor fields). In the first case, we used some simple eccentricity functions for dispersion tensors for two fractions simultaneously, which we call surrogate entropy. In the second case, to visualize the anisotropy of the velocity fields of three fractions simultaneously, we used an ordered array (3-vector) of eccentricities for the color representation through decomposition in three basic colors. In the case of a multi-stream flow, we used cluster analysis methods to identify sections of a multi-stream flow (beams) and used glyphs to visualize the entire set of beams (vector-tensor fields).

Kinematical evolution of Globular Clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 524-527
Author(s):  
Maria A. Tiongco ◽  
Enrico Vesperini ◽  
Anna Lisa Varri
Keyword(s):  
Angular Momentum ◽  
Structural Properties ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Three Dimensional ◽  
Stellar Populations ◽  
Velocity Space ◽  
Fundamental Understanding

AbstractWe present several results of the study of the evolution of globular clusters’ internal kinematics, as driven by two-body relaxation and the interplay between internal angular momentum and the external Galactic tidal field. Via a large suite of N-body simulations, we explored the three-dimensional velocity space of tidally perturbed clusters, by characterizing their degree of velocity dispersion anisotropy and their rotational properties. These studies have shown that a cluster’s kinematical properties contain distinct imprints of the cluster’s initial structural properties, dynamical history, and tidal environment. Building on this fundamental understanding, we then studied the dynamics of multiple stellar populations in globular clusters, with attention to the largely unexplored role of angular momentum.

Complex Time Methods and Chameleon Scalar Fields in the Dynamics of Spatial Extremes

2020 ◽  
Author(s):  
Dionysia Panagoulia ◽  
Kalomoira Zisopoulou
Keyword(s):  
Hardy Spaces ◽  
Scalar Fields ◽  
Coordinate Space ◽  
Multivariate Methods ◽  
Action Functional ◽  
Complex Time ◽  
Spatial Extremes ◽  
Engineering Department ◽  
Variable Reduction ◽  
E Mail

<p>Complex Time Methods and Chameleon Scalar Fields in the Dynamics of Spatial Extremes</p><p>Dionysia Panagoulia1 and Kalomoira Zisopoulou 2</p><p>1 School of Civil Engineering, Department of Water Resources and Environmental Engineering, National Technical University of Athens, Zografou, Greece. E-mail [email protected]</p><p> 2 Travaux Publics, Becket House, London, United Kingdom</p><p>It is shown that complex time in classical physics may transform the action functional Lagrangian and Lagrangian density processes to, among others, energy descriptive functionals. By imposing restrictions in the problem coordinate space as per need, such as Sobolev or Hardy spaces, or to the complex time plane such as the two variable Hilbert Space dependent Bergman. Decomposition new results are obtained which facilitate a better understanding of the mechanism governing spatial extremes in terms of flows. <br>The introduction of Khoury-Weltman type chameleon scalar fields will, by the recognition of existing oscillatory patterns, pave a connective chain of momenta between smaller and larger objects which will uncover the causal relationships between them which will allow for variable reduction in multivariate methods.</p>

scholarly journals The Natural Convective Heat Transfer in a Partially Divided Enclosure: A Study on the Influence of the Source Position

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Francesco Corvaro ◽  
Massimo Paroncini
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Dynamic Behaviour ◽  
Velocity Fields ◽  
Source Position ◽  
Square Enclosure ◽  
Nusselt Numbers ◽  
First Case ◽  
Rayleigh Numbers

The aim of this paper is to analyse the natural convective heat transfer generated by a source with a height of located in two different positions inside a square enclosure of side . In the first case, is 0.5 of while in the second case it is 0.4. The comparison is based both on the evaluation of the local and average Nusselt numbers at different Rayleigh numbers and on the study of the velocity fields at the same Rayleigh numbers in the two different configurations. The experimental analysis was carried out through a holographic interferometry, to study the heat transfer, and through a 2D-PIV system, to analyse the dynamic behaviour of the phenomenon. Finally, for = 0.5 we compared the experimental results with those obtained through the volume finite software Fluent 6.3.26. In the analysis, it is possible to see that the position of the source influences both the average Nusselt numbers on the hot surfaces and the development of a small bubble on the upper surface.

scholarly journals Continuous Histograms for Anisotropy of 2D Symmetric Piece-Wise Linear Tensor Fields

2021 ◽  
pp. 39-70
Author(s):  
Talha Bin Masood ◽  
Ingrid Hotz
Keyword(s):  
Volume Rendering ◽  
Transfer Functions ◽  
Anisotropy Field ◽  
Scalar Fields ◽  
Linear Interpolation ◽  
Tensor Fields ◽  
Interactive Interfaces ◽  
Scalar Invariants ◽  
Linear Scalar ◽  
Naive Approach

AbstractIn this chapter we present an accurate derivation of the distribution of scalar invariants with quadratic behavior represented as continuous histograms. The anisotropy field, computed from a two-dimensional piece-wise linear tensor field, is used as an example and is discussed in all details. Histograms visualizing an approximation of the distribution of scalar values play an important role in visualization. They are used as an interface for the design of transfer-functions for volume rendering or feature selection in interactive interfaces. While there are standard algorithms to compute continuous histograms for piece-wise linear scalar fields, they are not directly applicable to tensor invariants with non-linear, often even non-convex behavior in cells when applying linear tensor interpolation. Our derivation is based on a sub-division of the mesh in triangles that exhibit a monotonic behavior. We compare the results to a naïve approach based on linear interpolation on the original mesh or the subdivision.

Supersymmetric QFT in Six Dimensions

2020 ◽  
Author(s):  
Alessandro Tomasiello
Keyword(s):  
String Theory ◽  
Scalar Fields ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Tensor Fields ◽  
Conformal Field ◽  
High Energies ◽  
Six Dimensions ◽  
Full Classification

Quantum field theory (QFT) in six dimensions is more challenging than its four-dimensional counterpart: most models tend to become ill-defined at high energies. A combination of supersymmetry and string theory has yielded many QFTs that evade this problem and are low-energy effective manifestations of conformal field theories (CFTs). Besides the usual vector, spinor and scalar fields, the new ingredients are self-dual tensor fields, analogs of the electromagnetic field with an additional spacetime index, sometimes with an additional non-Abelian structure. A recent wave of interest in this field has produced several classification results, notably of models that have a holographic dual in string theory and of models that can be realized in F-theory. Several precise quantitative checks of the overall picture are now available, and give confidence that a full classification of all six-dimensional CFTs may be at hand.conformal field theories, supersymmetry, extra dimensions, holography, string theory, D-branes, F-theory

scholarly journals A Titius-Bode like law for stellar populations in the velocity space

2006 ◽  
Vol 2 (S235) ◽  
pp. 68-68
Author(s):  
Santiago Alcobé ◽  
Rafael Cubarsi
Keyword(s):  
Velocity Dispersion ◽  
Energy Levels ◽  
Average Energy ◽  
Maximum Velocity ◽  
Stellar Populations ◽  
Thin Disk ◽  
Thick Disk ◽  
Velocity Space ◽  
Heating Process ◽  
Stellar Velocity

AbstractThe statistical algorithm MEMPHIS (Cubarsi & Alcobé 2006) was applied to a large sample from the Hipparcos catalogue with the full space motions (Cubarsi & Alcobé 2004), to segregate the kinematic populations of the solar neighbourhood. Four stellar populations were obtained, namely early-thin disk, young-thin disk, the whole thin disk (which contains both previous populations plus the continuum of old thin disk stars), and the thick disk population. Now, we wish to point out two main results from the analysis of such a segregation (Alcobé & Cubarsi 2005). First, the relationship between the maximum stellar velocity of a sample and its average age τ can be approximated by the relation |V|max ∝ τ. Second, the local stellar populations can be described from a Titius-Bode like law (TBLL) for the radial velocity dispersion, $\sigma_1 = 6.6 \, (\frac43)^n$, so that for values n = 2, 3, 5, 8 it determines some average energy levels of discrete populations, while for continuous intervals n ≤ 5 and n ≥ 7 it describes the velocity-age evolution of thin and thick disk components, as shown in the Table below.Thus, the velocity dispersions of the local kinematic populations seem to follow a geometrical progression, allowing us to do an analogy with the old Titius-Bode distribution for keplerian orbits, although a physical explanation for the later law remains still open (Lynch 2003). Indeed, such a TBLL in the velocity space could be already conjectured from previous published kinematic parameters of the Galactic components (e.g. Alcobé & Cubarsi 2001). As in the keplerian case, it is possible to argue that velocity dispersion values have too much uncertainty, but, even so, it is not possible to ignore anymore such a resemblance.Such results are consistent with Galactic formation models that predict some quasi-continuous stellar populations in the sense that the continuity is constricted by σ1 levels of the TBLL. The physical meaning of the variable n involved in the TBLL may be related with the average epicycle energy ER ~ σ21 of the stars representative of the disk heating process. It shows continuity from n = 3 to 5 for the thin disk, and from 7 to 8 for the thick disk, but discreteness from n = 2 to 3 between early-thin and young-thin disk, and from 5 to 8 between thin and thick disk components. For the thin disk, for example, the level n = 5 should represent the saturation point of maximum velocity dispersion, likely corresponding to the limited predicted by the observed wavenumber of spiral structure of the Milky Way, while the discontinuity from n = 5 to 7 indicates an abrupt jump in the average energy, that was produced when the thick disk was formed about 10±1 Gyr ago.

scholarly journals A DISCRETIZED VERSION OF KALUZA–KLEIN THEORY WITH TORSION AND MASSIVE FIELDS

1996 ◽  
Vol 11 (13) ◽  
pp. 2403-2418 ◽  
Author(s):  
NGUYEN AI VIET ◽  
KAMESHWAR C. WALI
Keyword(s):  
Noncommutative Geometry ◽  
Vector Fields ◽  
Complex Structure ◽  
Scalar Fields ◽  
Type Model ◽  
Internal Space ◽  
Tensor Fields ◽  
Fifth Dimension ◽  
Klein Theory ◽  
Kaluza Klein

We consider an internal space of two discrete points in the fifth dimension of the Kaluza–Klein theory by using the formalism of noncommutative geometry — developed in a previous paper1 — of a spacetime supplemented by two discrete points. With the non-vanishing internal torsion two-form there are no constraints implied on the vielbeins. The theory contains a pair of tensor fields, a pair of vector fields and a pair of scalar fields. Using the generalized Cartan structure equation we are able to uniquely determine not only the Hermitian and metric-compatible connection one-forms, but also the nonvanishing internal torsion two-form in terms of vielbeins. The resulting action has a rich and complex structure, a particular feature being the existence of massive modes. Thus the nonvanishing internal torsion generates a Kaluza–Klein type model with zero and massive modes.

scholarly journals Color in visual representations of COVID-19 pandemic: content analysis of publications in the Russian-language digital mass media

2020 ◽  
pp. 79-93
Author(s):  
Yulia Alexandrovna Griber ◽  
Elena Evgenjevna Suchova
Keyword(s):  
Content Analysis ◽  
Mass Media ◽  
Color Image ◽  
Visual Representations ◽  
Russian Language ◽  
Research Database ◽  
Dominant Form ◽  
Color Representation ◽  
First Case ◽  
The Russian Language

The goal of this article consists in presenting the results on analysis of visual representations of COVID-19 pandemic in the Russian-language digital mass media from the perspective of the functions of color, its correlation with the theme, frequency of dominant shade of images and its dynamics. Publications in the digital mass media for the period from February to May 2020 related to topic of Coronavirus became the material for this research. The time framework captured the period of 100 days, since January 31, when the first case of coronavirus was confirmed in Russia. The author applied multi-stage cluster strategy; the material was sorted into clusters using the search function by the dominant color of Google. The search was conducted by 12 key colors: 9 chromatic (red, orange, yellow, green, blue, dark blue, purple, pink, and brown), and 3 achromatic (white, grey, and black). For each main color, the research database included first 100 articles. The study was carried out using the method of content analysis. Statistical analysis demonstrated that color of the image correlates with the theme of information text, given overall assessment of the situation and its development prospects. The dominant form of visual representation of COVID-19 pandemic in the Russian-language mass media is depiction of the source of coronavirus infection, which presented in the online publications in all main colors, except two achromatic – white and grey. The dynamics of color representation of coronavirus is associated with the important events for development of the situation. Coincidence and changeability of the color image of coronavirus reflects high level of social anxiety, which is supported and aggravated by publication on the uncertain nature of the virus and course of the disease caused by it. The author sees solution of the problem in reserving the grey color common to the visual image of coronavirus. In this case, the color would correspond with the scientific reality (since there is no color without the light), and the image of coronavirus, purified from the aggressive color, would become less threatening and virulent.

scholarly journals The PN.S ETG survey

2016 ◽  
Vol 12 (S323) ◽  
pp. 279-283 ◽  
Author(s):  
M. Arnaboldi ◽  
C. Pulsoni ◽  
O. Gerhard ◽  
Keyword(s):  
Angular Momentum ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Velocity Fields ◽  
Field Of View ◽  
Line Of Sight ◽  
Early Type ◽  
Velocity Data ◽  
Pn Velocity ◽  
Current Sample

AbstractWe have analyzed the velocity fields in the halos of thirty-three early-type galaxies (ETGs) with planetary nebulae (PNs) as tracers, reaching radii of up to ~8Re. The sample comprises twenty-five galaxies from the Planetary Nebulae Spectrograph (PN.S) ETG survey and eight further galaxies with extended PN velocity data from the literature and new Counter-Dispersed imaging observations. The catalogues from these thirty-three ETGs provide astrometric positions and heliocentric line-of-sight velocities for a total of 8354 extragalactic PNs. All these catalogues are treated homogeneously for the identification of kinematic outliers and the separation between main galaxy/satellites in each galaxy field-of-view. We discuss the rotation velocities, velocity dispersion profiles and radial trends of the specific angular momentum, separating between slow rotators and fast rotators. We compare the properties of the V/σ(R) and σ(R) profiles with predictions of 2D velocity fields from hydro-dynamical cosmological simulations. We briefly mention the possible origin of the quasi-Keplerian steeply decreasing profile galaxies which encompasses about one fourth of the current sample.

scholarly journals DUALITY SYMMETRIES IN NONLINEAR GAUGE THEORIES

1999 ◽  
Vol 14 (07) ◽  
pp. 1139-1149 ◽  
Author(s):  
MINAKO ARAKI ◽  
YOSHIAKI TANII
Keyword(s):  
Sigma Models ◽  
Gauge Theories ◽  
Scalar Fields ◽  
Antisymmetric Tensor ◽  
Symmetry Groups ◽  
Tensor Fields ◽  
Duality Symmetry ◽  
Nonlinear Gauge ◽  
Field Strengths ◽  
Nonlinear Sigma Models

Duality symmetries are discussed for nonlinear gauge theories of (n-1)th rank antisymmetric tensor fields in general even dimensions d=2n. When there are M field strengths and no scalar fields, the duality symmetry groups should be compact. We find conditions on the Lagrangian required by compact duality symmetries and show an example of duality invariant nonlinear theories. We also discuss how to enlarge the duality symmetries to noncompact groups by coupling scalar fields described by nonlinear sigma models.

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