VISUAL ANALYSIS OF TIME-VARYING MULTIDIMENSIONAL DATA SETS Bondarev, A. E.
International archives of the photogrammetry, remote sensing and spatial information sciences.,
05/2023, Letnik:
XLVIII-2/W3-2023
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
This paper contains a description of computational experiments on the application of elastic maps to the analysis of time-varying volumes of textual information. Elastic maps are considered as a tool ...to provide analytical work with textual information and large information arrays of data. This paper presents the results of numerical experiments on the study of data volumes consisting of frequencies of joint use of words from different parts of speech, for instance “noun + verb” or “adjective + noun”. We consider text collections in Russian for experiments. Previously, static information arrays were mostly considered. It is for them methods of data analysis and methods of visual analytics were developed. Nevertheless, data comes in all the time in various areas of human activity. And in practice it is necessary to know how the cluster picture of multidimensional data volume changes over time. The paper describes the numerical experiments for real time-varying multidimensional data sets. Such experiments allows to analyze the evolution of cluster structure for multidimensional data and to trace the evolution for separate cluster.
The paper is devoted to problems of visual analysis of multidimensional data sets using an approach based on the construction of elastic maps. This approach is quite suitable for processing and ...visualizing of multidimensional datasets. The elastic maps are used as the methods of original data points mapping to enclosed manifolds having less dimensionality. Diminishing the elasticity parameters one can design map surface which approximates the multidimensional dataset in question much better. Then the points of dataset in question are projected to the map. The extension of designed map to a flat plane allows one to get an insight about the structure of multidimensional dataset. The paper presents the results of applying elastic maps for visual analysis of multidimensional data sets of medical origin. Previously developed data processing procedures are applied to improve the results obtained - pre-filtering of data, removal of separated clusters (flotation), quasi-Zoom.
Abstract
In modern problems of mathematical modeling in computational gas dynamics, it is increasingly necessary to implement parametric studies. In these cases, the key factors of the problem under ...consideration vary with the chosen step within the given ranges. Calculations of this kind can be effectively carried out by constructing a generalized computational experiment. A generalized computational experiment is a computational technology that combines the solution of mathematical modeling problems, parallel technologies, and visual analytics technologies. The results of a generalized computational experiment are multidimensional arrays, where the dimension of the arrays corresponds to the number of key factors. Processing and visual presentation of such arrays requires solving a number of separate tasks. The processing and visual presentation of the results are carried out for target functionals represented as a function of many variables. The report presents an examples of solving specific processing and visualization problems based on the implemented generalized computational experiment for 3D cone in supersonic flow.
•First direct measurements of the electrocaloric effect in a ferrielectric (NH4)2SO4.•Small effect of the electric field on the temperature and entropy of the transition.•High extensive and low ...intensive electrocaloric efficiency.•No conversion between conventional and inverse electrocaloric effects.•Contribution of Joule heat to the temperature change under the electric field.
Display omitted
The influence of an electric field on the phase transition parameters and the electrocaloric response in ferrielectric (NH4)2SO4 was studied using a universal multifunctional adiabatic calorimeter. The very low sensitivity of the phase transition temperature to the electric field, dT0/dE ≈ 5·10-3 K/(kV/cm), was shown to be the reason for the low maximum value of the intensive electrocaloric effect, ΔTAD, at E = 11 kV/cm: direct and indirect measurements gave the values of 0.01 K and 0.05 K, respectively. However, the extensive electrocaloric response revealed by an analysis of the entropy–temperature–electric field phase diagram was relatively large, with a value of ΔSECE ≈ − 19 J/kg K, due to the significant contribution of a jump in the excess entropy to the total value, δS0/ΔS0 ~ 0.37. An additional irreversible increase in temperature under the electric field was associated with the Joule effect and indicated a significant electrical conductivity of ammonium sulphate.
Powders based on tantalum disilicide and silicon carbide were fabricated by mechanical activation-assisted SHS of reaction mixtures, with SiC concentration varied from 10 to 70%. The single- and ...double-layer composite targets were produced by hot pressing and further utilized for deposition of Si-Ta-C-(N) coatings by magnetron sputtering. The optimal hot pressing regimes, which allowed the production of dense ceramics with a hierarchical structure at 10 and 30% SiC, were determined. These ceramics were characterized by a relative density of 96–97%, hardness of ~19 GPa, and fracture toughness of 6.5–6.7 MPa × m1/2. The nanocomposite Si-Ta-C-N coatings consisted of fcc Ta(Si,C,N) solid solution (TaSi2–30%SiC target) and Ta5Si3 compound (TaSi2–10%SiC target) embedded in an amorphous matrix. Depending on the elemental composition, hardness and Young's modulus of the coatings were 16–26 GPa and 155–268 GPa, respectively. The coatings are characterized by high thermal stability and oxidation resistance at temperatures up to 800 °C. Tribological tests demonstrated the decrease of the coefficient of friction (CoF) of the coatings with increasing temperature: from 0.38 (25 °C) to 0.28 (600 °C) and 0.23 (800 °C). The low wear rate and CoF of the Si-Ta-C-N coatings at elevated temperatures are explained by the formation of a thin (~100 nm) oxide layer and TaSixOy microfibers on the coating surfaces.
•TaSi2-SiC powders were fabricated by mechanical activation-assisted combustion synthesis.•TaSi2-xSiC targets (x = 10, 30) had high relative density, hardness, and fracture toughnes.•Si-Ta-C-(N) coatings consisted of small (<3 nm) Ta(Si,C,N) or Ta5Si3 crystallites embedded in an amorphous matrix.•Si-Ta-C-(N) coatings showed high thermal stability and oxidation resistance at temperatures up to 800 °C.•Si-Ta-C-(N) coatings demonstrated low friction and wear rate at elevated temperatures.
The presented research considers the problems of studying the cluster structure of multidimensional data volumes. This paper presents the results of numerical experiments on the study of data volumes ...consisting of frequencies of joint use of words from different parts of speech, for instance “noun + verb” or “adjective + noun”. The volumes of data are obtained from samples from text collections in Russian. The aim of the research is to analyze the cluster structure of the studied volume and semantic proximity of words in clusters and subclusters. The hypothesis was used that words with similar meaning should occur in approximately the same context. In this regard, in the space of features, they will be at a relatively close distance from each other, while differing words will be at a more distant distance from each other. Research is carried out using elastic maps, which are effective tools for visual analysis of multidimensional data. The construction of elastic maps and their extensions in the space of the first three principal components makes it possible to determine the cluster structure of the studied multidimensional data volumes. Such analysis can be useful in the tasks of confronting negative verbal influences such as fake news, hidden propaganda, involvement in sects, verbal manipulation, etc. Also this approach can be applied to text collections having medical origin.
PDF
