Multi-service resource queue with the multy-component Poisson arrivals

In many papers devoted to telecommunication systems, multiservice queueing models with heterogeneous customer arrivals are given. As a rule, there is streaming traffic, corresponding to the audio and video conference, and elastic traffic, corresponding to the data and file transmission. Different types of traffic require different quality of service, therefore the multi-service systems are also differentiated service systems. Such papers are aimed at developing a framework for estimating the quality of service indicators in new generation multi-service networks. This paper considers a multiservice resource queueing system with three Poisson arrivals, one of which is splitting. The equation for the probabilities distribution of the total resource amounts on the system blocks is compiling by the dynamic screening method, and using the characteristic function of the stationary distribution, the solution is obtaining. The numerical characteristics of the system performance are obtained by the method of moments using characteristic function. A numerical example shows that arrivals intensity growing increases optimal total resource amounts on system blocks in the system with limited resources, and the splitting arrivals affect the correlation between total resource amounts

Influence of a binder on the electrochemical behaviour of Si/RGO composite as negative electrode material for Li-ion batteries

Received: 02.12.2020. Accepted: 21.12.2020. Published:30.12.2020.A composite consisting of silicon nanoparticles and reduced graphene oxide nanosheets (Si/RGO) was studied as a promising material for the negative electrode of lithium-ion batteries. Commonly used polyvinylidene fluoride (PVdF) and carboxymethyl cellulose (CMC) served as a binder. To reveal the influence of the binder on the electrochemical behaviour of the Si/RGO composite, binder-free electrodes were also prepared and examined. Anode half-cells with composites comprising CMC as a binder demonstrated the best properties: capacity over 1200 mAh·g–1, excellent cycling performance and good rate capability up to 1.0C.This work was performed with financial support from the Ministry of Science and Higher Education of Russian Federation, project ID RFMEFI60419X0235

Synthesis of Nanosized Powders with the Structure of Perovskite

The aim of this work was to create and study of ferrite lanthanum powders, using sol-gel technology with participation of auto-combustion. After the sintering at a temperature of 1123 K only one phase, which corresponded to the solid solution LaFeO3, was obtained. It was found that obtained powders were agglomerated, and the size of the crystallites were less than 50 nm. It was researched the processes of phase transitions and chemical reactions, which the heating of synthesized material in the temperature range 298 - 1173 K accompany. It was shown that the process of forming of LaFeO3 phase occurs by heating the powder at a temperature of 1043 K. Keywords: sol-gel technology, lanthanum ferrite, nanoscale powders, agglomerates, thermal reaction.</span

Using infinite‑server resource queue with splitting of requests for modeling two‑channel data transmission

New Radio Access Technology 3GPP New Radio has become the fundamental wireless technology in the fifth-generation networks, which allows us to achieve high data rates due to the ability to work in the millimeter-wave band. But the key feature and the main problem of 5G New Radio networks is that people themselves, cars, buildings, etc. are signal blockers, while the base stations of the fourth generation networks have widescreen broadcasting and such small obstacles do not cause loss of connection. Service providers and mobile operators are already testing the proposed technology. In this connection, the scientific community has the task of analyzing the performance of these systems and increasing it in the future. Currently, there are known studies of “basic” mathematical models of such networks. By this term, we mean models built in the simplest possible assumptions. However, due to the justified necessity of introducing new technology into the daily lives of subscribers, service providers pose the scientific community with the task of analyzing the effectiveness of the most appropriate mathematical models. For example, a technology of splitting transmitted data into two streams using as 5G and both 4G transmission technologies is considered now by 3GPP Project Coordination Group. The paper is devoted to such a problem. We consider a mathematical model of the message transmitting with the implementation of the splitting function in the communication networks of New Radio technology in the form of a resource queueing system with a renewal arrival process and non-exponential service. For this problem, an approximation of a stationary two-dimensional probability distribution of the number of occupied resources in parallel service units is obtained. It is shown that this approximation coincides with the Gaussian distribution, and its area of applicability is shown

Investigation of Growth Factors and Mathematical Modeling of Nutrient Media for the Shoots Multiplication In Vitro of Rare Plants of the Rostov Region

Micropropagation is an effective way to preserve the gene pool of threatened plants. This study is devoted to the mathematical modeling of nutrient media and the study of the effect of mT (meta-topoline) on the multiplication of shoots of Hedysarum grandiflorum, Hyssopus cretaceus, and Matthiola fragrans in vitro in comparison with benzylaminopurine (BAP) and kinetin (KT). Initiation was performed on an MS medium with 0.5 mg/L BAP. For shoots multiplication, MS, B5, and WPM media were used with the addition of mT, BAP, KT. For H. grandiflorum, the multiplication coefficient of shoots was highest on medium B5 with the addition of mT at a concentration of 1 mg/L—2.90 shoots per plant, for H. cretaceus—B5 + 0.5 mg/L mT, and for M. fragrans—B5 + 1 mg/L KT. A positive effect of mT on H. grandiflorum and M. fragrans in vitro was found. The efficiency of using KT for H. cretaceus shoot multiplication is shown. The effectiveness of the B5 nutrient medium for H. grandiflorum and M. fragrans was determined. The positive effect of WPM for H. cretaceus micropropagation has been demonstrated. It is not recommended to use the MS media for micropropagation of these plant species