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A. A. Snarskii

Publications and source records attributed to A. A. Snarskii.

At least 19 recordsLinked to original sources
arXiv2024

Graph structural complexity

Introduced the quantitative measure of the structural complexity of the graph (complex network, etc.) based on a procedure similar to the renormalization process, considering the difference between actual and averaged graph structures on different scales. The proposed concept of the graph structural complexity corresponds to qualitative comprehension of the complexity. The proposed measure can be obtained for the weighted graphs also. The structural complexities for various graph types were found - the deterministic infinite and finite size graphs, artificial graphs of different natures including percolation structures, and the time series of cardiac rhythms mapped to complex networks using the parametric visibility graph algorithm. The latter reaches a maximum near the formation of a giant component in the graph or at the percolation threshold for 2D and 3D square lattices when a giant cluster having a fractal structure has emerged. Therefore, the graph structural complexity allows us to detect and study the processes similar to a second-order phase transition in complex networks. A new node centrality index, characterizing the structural complexity of a certain node within the graph structure is introduced also, it can serve as a good auxiliary or generalization to the local clustering coefficient. Such an index provides another new ranking manner for the graph nodes. Being an easily computable measure, the graph structural complexity might help to reveal different features of complex systems and processes of the real world.

physics.soc-ph↗
arXiv2022

Forward and backward mapping of image to 2D vector field using fiber bundle color space

We introduce the concept of a fiber bundle color space, which acts according to the psychophysiological rules of trichromacy perception of colors by a human. The image resides in the fiber bundle base space and the fiber color space contains color vectors. Further we propose the decomposition of color vectors into spectral and achromatic parts. A homomorphism of a color image and constructed two-dimensional vector field is demonstrated that allows us to apply well-known advanced methods of vector analysis to a color image, i.e. ultimately give new numerical characteristics of the image. Appropriate image to vector field forward mapping is constructed. The proposed backward mapping algorithm converts a two-dimensional vector field to color image. The type of image filter is described using sequential forward and backward mapping algorithms. An example of the color image formation on the base of two-dimensional magnetic vector field scattered by a typical pipe line defect is given.

cs.GR↗
arXiv2016

K-method of cognitive mapping analysis

Introduced a new calculation method (K-method) for cognitive maps. K - method consists of two consecutive steps. In the first stage, allocated subgraph composed of all paths from one selected node (concept) to another node (concept) from the cognitive map (directed weighted graph) . In the second stage, after the transition to an undirected graph (symmetrization adjacency matrix) the influence of one node to another calculated with Kirchhoff method. In the proposed method, there is no problem inherent in the impulse method. In addition to "pair" influence of one node to another, the average characteristics are introduced, allowing to calculate the impact of the selected node to all other nodes and the influence of all on the one selected. For impulse method similar to the average characteristics in the case where the pulse method "works" are introduced and compared with the K-method.

cs.SI↗
arXiv2016

"Conjectural" links in complex networks

This paper introduces the concept of Conjectural Link for Complex Networks, in particular, social networks. Conjectural Link we understand as an implicit link, not available in the network, but supposed to be present, based on the characteristics of its topology. It is possible, for example, when in the formal description of the network some connections are skipped due to errors, deliberately hidden or withdrawn (e.g. in the case of partial destruction of the network). Introduced a parameter that allows ranking the Conjectural Link. The more this parameter - the more likely that this connection should be present in the network. This paper presents a method of recovery of partially destroyed Complex Networks using Conjectural Links finding. Presented two methods of finding the node pairs that are not linked directly to one another, but have a great possibility of Conjectural Link communication among themselves: a method based on the determination of the resistance between two nodes, and method based on the computation of the lengths of routes between two nodes. Several examples of real networks are reviewed and performed a comparison to know network links prediction methods, not intended to find the missing links in already formed networks.

cs.SI↗
arXiv2014

Rotating thermoelectric device in periodic steady state

We propose the rotating thermoelectric (TE) device comprising of the single TE conductor operating in two periodical steady state modes: the switching periodical mode (P-mode) when hot and cold ends of the TE conductor are periodically instantly reversed and the continuous sinusoidal mode (S-mode) when the temperature of TE conductor edges varies continuously according to sine wave. Power generation and cooling regimes of rotating (TE) device in the periodic steady state was studied analytically. The efficiency and the cooling temperature of rotating TE device was found to depend not only on the dimensionless TE figure of merit, but also upon an additional dimensionless parameter comprising of the rotation period, the size and the thermal diffusivity of the TE conductor. The proposed analytical method can be generalized to even more complex timing modes and allows to solve the optimization problem for TE device parameters. We investigated whether it is possible to achieve better performance for rotating TE device comparing to conventional stationary steady state, the S-mode was shown to demonstrate deeper cooling at certain times.

cond-mat.mtrl-sci↗
arXiv2014

From the time series to the complex networks: the parametric (dynamical) natural visibility graph

We present the modification of natural visibility graph (NVG) algorithm used for the mapping of the time series to the complex networks (graphs). We propose the parametric natural visibility graph (PNVG) algorithm. The PNVG consists of NVG links, which satisfy an additional constraint determined by a newly introduced continuous parameter - the view angle. The alteration ofview angle modifiesthe PNVG and its properties such as the average node degree, average link length of the graph as well as cluster quantity of built graph etc. Wecalculated and analyzed different PNVG properties depending on the view angle for different types of the time series such as the random (uncorrelated, correlated and fractal) and cardiac rhythm time series for healthy and ill patients. Investigation of different PNVG properties shows that the view angle gives a new approach to characterize the structure of the time series that are invisible in the conventional version of the algorithm. It is also shown that the PNVG approach allows to distinguish, identify and describe in detail various time series.

physics.data-an↗
arXiv2013

Kinetic properties in inhomogeneous self-aware media

The new framework for finance is proposed. This framework based on three known approaches in econophysics. Assumptions of the framework are the following: 1. For the majority of situations market follows non-arbitrage condition. 2. For the small number of situations market influenced by the actions of big firms. 3. If actions of big players lead to the arbitrage opportunity, small players could self-organize to take advantage of this opportunity. The framework is an attempt to combine approaches of Bouchaud, Gabaix, Sornette, Stanley and coauthors. Suggested framework is applied for the analysis of market impact models, behavior of big players, self-organization of market firm and volatility description.

q-fin.GN↗
arXiv2013

Compactified Horizontal Visibility Graph for the Language Network

A compactified horizontal visibility graph for the language network is proposed. It was found that the networks constructed in such way are scale free, and have a property that among the nodes with largest degrees there are words that determine not only a text structure communication, but also its informational structure.

cs.CL↗
arXiv2012

Evolution of burst distribution in fiber bundle model

We consider a fiber bundle model with a equal load sharing and uniformly distributed breakdown thresholds. A unified probability-theoretic approach was used to describe bundle under continuous and discrete load increase. It was shown that the ratio of distribution D(d) of avalanches of sizes d to the number of bundle load steps exactly corresponds to burst probability of size d. Evolution of s - power law distribution exponent of D(d) was studied as a function of loading step and bundle size. It was shown that s does not depend on bundle size. In the numerical experiment, dependence s on loading step was obtained with fiber bundle size up to N=10^10. The regions of s values constancy and the transition region were found. A distribution of fiber bursts on each loading step was recovered in the numerical simulations. It was shown that a change in the type of this distribution is the reason for evolution of s values in the range of -3 - -5/2.

cond-mat.dis-nn↗
arXiv2011

On the wiedemann-franz law in thermoelectric composites

Theoretical analysis of the effect of thermoelectric phenomena on the relation of effective electrical and thermal conductivity in the macroscopically inhomogeneous media is carried out. Plane-layered structures, two-dimensional self-dual and three-dimensional randomly inhomogeneous media are examined. It is shown that the relation of effective electrical to thermal conductivity, which is independent of concentration in so-called Wiedemann-Franz media, in the case of high values of internal thermoelectric figure of merit can be considerably different from the one for the local values in each phase. The decrease of the relation may have negative impact on the effective figure of merit of composites and thus lead to the decrease of thermoelectric devices efficiency.

cond-mat.mtrl-sci↗
arXiv2011

Effect of surface micro- and nanolayers of composite particles on thermoelectric figure of merit (phenomenological approach)

Non-symmetric variants of self-consistent field theory are proposed that served the basis for theoretical investigation of the effect of thermal conductivity of composite particles surface layers on the effective thermoelectric figure of merit. It is shown that in some cases thermoelectric figure of merit can be essentially improved due to the presence of a shell.

cond-mat.mtrl-sci↗
arXiv2011

Thermoelectric properties of macroscopically inhomogeneous composites

Review of theoretical methods for description of thermoelectrical properties of two-phase macroscopically inhomogeneous media is given. Description by means of a hierarchical model of percolation structure is given, allowing a description on a qualitative and quantitative level of the basic regularities of effective thermoelectric coefficient close to flow threshold.

cond-mat.mtrl-sci↗
arXiv2010

Detection Implicit Links and G-betweenness

A concept of implicit links for Complex Networks has been defined and a new value - cohesion factor, which allows to evaluate numerically the presence of such connection between any two nodes, has been introduced. We introduce a generalization of such characteristics as the betweenness, which allows to rank network nodes in more details. The effectiveness of the proposed concepts is shown by the numerical examples.

cond-mat.dis-nn↗
arXiv2010

Power law in website ratings

In the practical work of websites popularization, analysis of their efficiency and downloading it is of key importance to take into account web-ratings data. The main indicators of website traffic include the number of unique hosts from which the analyzed website was addressed and the number of granted web pages (hits) per unit time (for example, day, month or year). Of certain interest is the ratio between the number of hits (S) and hosts (H). In practice there is even used such a concept as "average number of viewed pages" (S/H), which on default supposes a linear dependence of S on H. What actually happens is that linear dependence is observed only as a partial case of power dependence, and not always. Another new power law has been discovered on the Internet, in particular, on the WWW.

cs.IR↗
arXiv2009

Diagram of measurement series elements deviation from local linear approximations

Method for detection and visualization of trends, periodicities, local peculiarities in measurement series (dL-method) based on DFA technology (Detrended fluctuation analysis) is proposed. The essence of the method lies in reflecting the values of absolute deviation of measurement accumulation series points from the respective values of linear approximation. It is shown that dL-method in some cases allows better determination of local peculiarities than wavelet-analysis. Easy-to-realize approach that is proposed can be used in the analysis of time series in such fields as economics and sociology.

stat.AP↗
arXiv2008

Dynamic Network of Concepts from Web-Publications

The network, the nodes of which are concepts (people's names, companies' names, etc.), extracted from web-publications, is considered. A working algorithm of extracting such concepts is presented. Edges of the network under consideration refer to the reference frequency which depends on the fact how many times the concepts, which correspond to the nodes, are mentioned in the same documents. Web-documents being published within a period of time together form an information flow, which defines the dynamics of the network studied. The phenomenon of its structure stability, when the number of web-publications, constituting its formation bases, increases, is discussed

cs.IT↗
arXiv2008

Peculiarities of the Correlation between Local and Global News Popularity of Electronic Mass Media

One of the approaches to the solution of the navigation problem in current information flows is ranking the documents according to their popularity level. The definition of local and global news popularity which is based on the number of similar-in-content documents, published within local and global time interval, was suggested. Mutual behavior of the documents of local and global popularity levels was studied. The algorithm of detecting the documents which received great popularity before new topics appeared was suggested.

cs.IT↗