Modelling Self-similar Traffic Of Multiservice Networks

Simulation modelling is carried out, which allows adequate describing the traffic of multiservice networks with the commutation of packets with the characteristic of burstiness. One of the most effective methods for studying the traffic of telecommunications systems is computer simulation modelling. By using the theory of queuing systems (QS), computer simulation modelling of packet flows (traffic) in modern multi-service networks is performed as a random self-similar process. Distribution laws such as exponential, Poisson and normal-logarithmic distributions, Pareto and Weibull distributions have been considered.The distribution of time intervals between arrivals of packages and the service duration of service of packages at different system loads has been studied. The research results show that the distribution function of time intervals between packet arrivals and the service duration of packages is in good agreement with the Pareto and Weibull distributions, but in most cases the Pareto distribution prevails.The queuing systems with the queues M/Pa/1 and Pa/M/1 has been studied, and the fractality of the intervals of requests arriving have been compared by the properties of the estimates of the system load and the service duration. It has been found out that in the system Pa/M/1, with the parameter of the form a> 2, the fractality of the intervals of requests arriving does not affect the average waiting time and load factor. However, when ≤2, as in the M/Pa/1 system, both considered statistical estimates differ.The application of adequate mathematical models of traffic allows to correctly assess the characteristics of the quality of service (QoS) of the network

The origin, conditions and mechanism for the formation of alpine-type hyperbasites of the Lesser Caucasus

The problem of hyperbasites origin is one of the widely discussed topics in geology. This is because they often appear when no expected. Their development does not correspond to the general regularities of the geological complexes’ development. Therefore, when problematic instances of hyperbasites appear, discussion is inevitable. This is due to the imperfections of existing concepts, which are not without flaws. The essence of this concept lies in the fact that during the rotation of the Earth around its axis, geodynamic forces are formed. The hyperbasites complex by its nature belongs to deep igneous formations formed at the initial stage of development of volcano-plutonic processes, where the composition of magmatic products was not subject to decomposition. In general, the origin of igneous rocks is associated with deep anomalous processes, which were formed under the influence of geodynamic forces, where decompression of mantle matter occurs, causing a catastrophic increase in the volume of mantle matter, as well as the associated development of volcanoplutonic processes. Hyperbasites are formed both in divergent and convergent zones of the Earth’s crust. The main factor for their formation is high pressure – deep thermodynamic conditions, where there are no favorable thermodynamic conditions for the complete separation of magmatic melts by composition. The emergence of hypermafic rocks on the surface is associated with geotectonic or denudation processes. Denudation processes can expose only those hypermafic formations that are located at the site of formation. These zones include ancient platforms, sheets, terranes, etc., which were cut by deep erosion processes. As for those hyperbasic formations that are classified as alpinotype hyperbasites, they were moved to the structure of the Alps-Himalayan folded zone from the basement with a collision with subsequent geotectonic processes, where they formed in the bed of the Paleotethys Ocean, both in the process of divergence and convergence. The noted pattern of formation and the mechanism of formation of alpine-type hyperbasites clearly corresponds to the patterns of development of geodynamic forces in the face of the Earth, also with natural laws, which are the main factors in the evolution of the Earth’s crust. From the standpoint of KDEZK, the origin, mechanism of formation, as well as the form of distribution of alpinotype hypermafic rocks of the Lesser Caucasus occurred in the Paleotethys bed, under different thermodynamic conditions and at depths. Further, as a result of the collision, it participated in the formation of folded zones of the Lesser Caucasus. Within the Lesser Caucasus, two genetic types of hypermafic rocks are exposed. Some of them correspond to the convergent zone of the Tethys paleocean, while others correspond to divergent zones. In terms of ore content, the most promising are those hypermafic rocks that are genetically related to convergent zones

Inheritance of cleistogamy in interspecific hybridization of Gossypium barbadense L.

Studies of the inheritance and and variability of chasmo- and cleistogamous types of cotton flower on the base of intraspecies hybridization of Gossypium barbadense L. are an urgent genetical task, whose applications involve plant breeding and seed industry. The purpose of our study was to determine the genetic control of this trait on the base of the regularity of alternative chasmo- and cleistogamous types of flowers in intraspecific hybrids of G. barbadense species. It is of theoretical and practical significance in the development of isogenic forms, lines, and varieties with the fully closed cleistogamous type of flowers, possessing important commercial traits. A pioneering method was elaborated for determining the genetic control of chasmo- and cleistogamous types of flowers in inrtaspecific hybridization of Gossypium barbadense L., which was a continuation of our studies on interspecific cotton hybridization. Two strategies were applied to the genetic analysis of hybrids: (1) paired reciprocal hybrids F1, F2 and (2) backcrossed hybrids Fb. On the grounds of these strategies, we determined the inheritance mode of flower types in reciprocal hybrids F1, which possessed the c1cg1Cg2cg2 genotype with chasmogamous flowers without reciprocal difference. The classes segregated in F2 as follows: 1 (cg1cg1Cg2Cg2) : 2 (cg1cg1Cg2cg2) : 1 (cg1cg1cg2cg2), where cleistogamy was double recessive (This trait shows the complete dominance inheritance pattern.) Segregation into two phenotypic classes occurs in the 3:1 ratio, i.e., three plants with chasmogamous flowers per one cleistogamous. The segregation Fb is 1:1; i.e., 1 chasmogamous : 1 cleistogamous. Thus, cotton chasmogamy is inherited in F2 according to the Mendelian law in a completely dominant manner: 3:1, which is proven by the Fb cross

Fabrication and characterization of porous mullite ceramics derived from fluoride assisted Metakaolin Al OH 3 annealing for filtration applications

In this work, polycrystalline mullite whiskers are synthesized by fluoride assisted method from metakaolin and several aluminum containing compounds such as amp; 947; Al OH 3, AlF3 3H2O, and amp; 945; Al2O3 corundum . The mullite formation and crystallization are assessed both in ex situ and in situ synchrotron X ray diffraction experiments under synthesis conditions. Polycrystalline mullite starts to form from metakaolin, Al OH 3, and AlF3 3H2O reactants at 680 C, whereas mullite does not form even at 1000 C when corundum is used. Porous mullite ceracmics are fabricated at sintering temperatures between 1000 and 1700 C and tested for water permeance. Scanning Electron Microscopy SEM and synchrotron X ray tomography amp; 956;CT reveal that ceramics are comprised of pore channels with an interlocked network of mullite whiskers. With competitive porosity up to 63 , compressive strength up to 20 MPa , and pure water flux up to 579 L m2 h at 1 bar , fabricated mullite ceramics are promising candidates for water filtration and purificatio

The charge transport mechanism in a new magnetic topological insulator MnBi0.5Sb1.5Te4

A new layered magnetic topological insulator with the composition MnBi0.5Sb1.5Te4 is obtained. The electrical conductivity in the plane of the layers and in the direction normal to the layers is studied in the range of temperatures of 1.4–300 K. It is found that a “metallic” character of the temperature dependence of the resistivity ρ(T) is observed in the range of temperatures of 50–300 K in both directions. Below T = 50 K, the value of ρ increases and demonstrates an uncommon temperature dependence with a characteristic feature in the region of the critical temperature Tc = 23 K. The increase in the resistance in the temperature range of 50–23 K is determined by the spin fluctuations and magnetic phase transition. Below Tc and down to 1.4 K, ρ(T) demonstrates a behavior characteristic for the weak localization effect, which is confirmed by the analysis of the data obtained when studying magnetoresistance.This work was financially supported by the Science Development Foundation under the President of the Republic of Azerbaijan (grants nos. EİF-BGM-4-RFTF-1/2017-21/04/1-M-02, EİF/MQM/Elm-Tehsil-1-2016-1(26)-71/16/1), Russian Foundation for Basic Research (grant no. 18-52-06009), St. Petersburg State University (grant no. 73028629) as well as the Spanish Ministerio de Ciencia e Innovación Foundation (grant no. PID2019-103910GB-I00).Peer reviewe

Temperature studies of Raman spectra in MnBi2Te4 and MnSb2Te4 magnetic topological insulators

Raman spectra of magnetic topological crystalline insulators in a wide temperature range including the magnetic ordering region are studied in detail. The anharmonicity parameters and Grüneisen mode parameters of Raman-active phonons in the studied crystals have been determined. It has been shown that the temperature dependence of the frequency of the (~48 cm–1) phonon in MnBi2Te4 coincides within ±0.1 cm–1 with the standard anharmonic model disregarding the spin–phonon coupling. The polarization dependences of Raman spectra in the MnSb2Te4 crystals indicate that Sb and Mn atoms are strongly mixed in them unlike the isostructural MnBi2Te4 crystals.This work was supported by the Azerbaijan Ministry of Science and Education (program “Development of the Preparation Technology of Multifunctional Convertors Based on Nanostructures”). E.V.C. acknowledges the s-upport of St. Petersburg State University (project no. 94031444).Peer reviewe