scholarly journals Study of Internet Structure Properties based on Metagraph Models

2020 ◽  
Vol 19 (4) ◽  
pp. 880-905
Author(s):  
Maxim Ivanov ◽  
Ivan Kalashnilov ◽  
Mekhran Nurullaev
Keyword(s):  
Mathematical Model ◽  
Comparative Analysis ◽  
Initial Data ◽  
Autonomous Systems ◽  
Software Implementation ◽  
Global Network ◽  
The Internet ◽  
Proposed Model ◽  
Internal Networks ◽  
Structure Properties

Studying the Internet its structure is usually divided into levels: Autonomous Systems Level (AS), Point of Presence Level (PoP), Router Level, etc. The global network can be represented on each of them as a graph based on the initial data obtained from open sources. Consideration of a network within the framework of a separate level facilitates analysis, but does not allow to systematically assess its structural properties when providing the connectivity between several segments of the network related, particularly, to the objects of critical information infrastructure. To overcome this contradiction, a mathematical model of the global network in the form of a metagraph was developed at the interface between AS-level and PoP-level that takes into account the characteristics of each level and allows to find bottlenecks both in the interdomain routing system and in the topology of internal networks of Internet providers. Based on the proposed model some structural phenomena of the global network are described: stub, multihomed and transit autonomous systems, content providers. Taking into account available data from open sources about Internet structure, a method for constructing a metagraph is proposed. A comparative analysis of tools that automate the process of analyzing a network model is carried out. The practice-oriented problems of finding a cutting subset in a metagraph were set. Certain areas of further research are software implementation of the models using module MGtoolkit in Python and the assessment of structural phenomena of Russian segments of the Internet.

scholarly journals AVERAGED MODEL OF A BOOST–TYPE PULSE DC CONVERTER

2019 ◽  
pp. 168-174
Author(s):  
Dmitriy Alekseevskiy ◽  
Olena Mikhailutsa ◽  
Andriy Pozhuyev
Keyword(s):  
Mathematical Model ◽  
Comparative Analysis ◽  
Current Mode ◽  
Widespread Application ◽  
Semiconductor Switches ◽  
Proposed Model ◽  
Reference Circuit ◽  
Circuit Elements ◽  
Averaged Models ◽  
Averaged Model

Urgency of the research. In the present paper, the questions of synthesis and application of the mathematical model of a boost-type DC converter, which has found widespread application in modern electrical devices and complexes, are considered. Target setting. Modeling of electrical complexes, which include semiconductor converters together with electromechanical, thermodynamic and other relatively slow processes, is faces the problem of a significant increase in simulation time. One way to solve this problem is to use the mathematical description of the semiconductor converter in the values averaged over the period of operation of the semiconductor switch. Actual scientific researches and issues analysis. In publications on this topic over the past few years, averaged models of DC converters of all basic types have been proposed. Both continuous and intermittent current modes are considered. Uninvestigated parts of general matters defining. In the models described in the publications, the continuous and intermittent current modes are considered as separate models in which ideal semiconductor switches are used. In addition, the adequacy of the models used is not given enough attention. The research objective. The objective of this work is to synthesize an averaged mathematical model of a boost-type DC converter, which would take into account the effect of direct voltage drops on the circuit elements in continuous and intermittent current modes, as well as assess the adequacy of applying the averaged approach. The statement of basic materials. In the article a description of an averaged mathematical model of a boost-type DC converter, which takes into account direct drops on the circuit elements and provides simulation both in continuous and intermittent current mode, is given. To confirm the performance and assess the adequacy of the proposed model, a joint simulation was performed using the proposed and reference (circuit) model, and its comparative analysis is given. Conclusions. The results of the comparative analysis confirmed the adequacy of the proposed model and revealed the occurrence of an error in the intermittent current mode, and also determined its cause.

THE DEVELOPMENT OF THE MATHEMATICAL MODEL OF PREDICTING THE INDICATORS OF ACCREDITATION OF TECHNICAL UNIVERSITIES IN THE RUSSIAN FEDERATION

2017 ◽  
pp. 27-38
Author(s):  
Olga Mikhaylovna Tikhonova ◽  
Alexander Fedorovich Rezchikov ◽  
Vladimir Andreevich Ivashchenko ◽  
Vadim Alekseevich Kushnikov
Keyword(s):  
Mathematical Model ◽  
System Dynamics ◽  
Regression Model ◽  
Oriented Graph ◽  
Real Data ◽  
Educational Process ◽  
Proposed Model ◽  
Linear Differential ◽  
The University ◽  
The Mathematical Model

The paper presents the system of predicting the indicators of accreditation of technical universities based on J. Forrester mechanism of system dynamics. According to analysis of cause-and-effect relationships between selected variables of the system (indicators of accreditation of the university) there was built the oriented graph. The complex of mathematical models developed to control the quality of training engineers in Russian higher educational institutions is based on this graph. The article presents an algorithm for constructing a model using one of the simulated variables as an example. The model is a system of non-linear differential equations, the modelling characteristics of the educational process being determined according to the solution of this system. The proposed algorithm for calculating these indicators is based on the system dynamics model and the regression model. The mathematical model is constructed on the basis of the model of system dynamics, which is further tested for compliance with real data using the regression model. The regression model is built on the available statistical data accumulated during the period of the university's work. The proposed approach is aimed at solving complex problems of managing the educational process in universities. The structure of the proposed model repeats the structure of cause-effect relationships in the system, and also provides the person responsible for managing quality control with the ability to quickly and adequately assess the performance of the system.

A Mathematical Model for the Anaerobic Digestion Process Applied to a Mixture of Night Soil and Septic Tank Sludge

1986 ◽  
Vol 18 (7-8) ◽  
pp. 239-248 ◽  
Author(s):  
Sung Ryong Ha ◽  
Dwang Ho Lee ◽  
Sang Eun Lee
Keyword(s):  
Mathematical Model ◽  
Anaerobic Digestion ◽  
Biomass Concentration ◽  
Gas Production ◽  
Septic Tank ◽  
Volatile Acid ◽  
Hydraulic Residence Time ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model

Laboratory scale experiments were conducted to develop a mathematical model for the anaerobic digestion of a mixture of night soil and septic tank sludge. The optimum mixing ratio by volume between night soil and septic tank sludge was found to be 7:3. Due to the high solids content in the influent waste, mixed-liquor volatile suspended solids (MLVSS) was not considered to be a proper parameter for biomass concentration, therefore, the active biomass concentration was estimated based on deoxyribonucleic acid (DNA) concentration in the reactor. The weight ratio between acidogenic bacteria and methanogenic bacteria in the mixed culture of a well-operated anaerobic digester was approximately 3:2. The proposed model indicates that the amount of volatile acid produced and the gas production rate can be expressed as a function of hydraulic residence time (HRT). The kinetic constants of the two phases of the anaerobic digestion process were determined, and a computer was used to simulate results using the proposed model for the various operating parameters, such as BOD5 and volatile acid concentrations in effluent, biomass concentrations and gas production rates. These were consistent with the experimental data.

scholarly journals On the Dragging Trajectory of Anchors in Clay for Merchant Ships

2021 ◽  
Vol 9 (2) ◽  
pp. 118
Author(s):  
Xinqing Zhuang ◽  
Keliang Yan ◽  
Pan Gao ◽  
Yihua Liu
Keyword(s):  
Mathematical Model ◽  
Structural Integrity ◽  
Indirect Measurement ◽  
Test System ◽  
Flow Rule ◽  
Burial Depth ◽  
Proposed Model ◽  
Depth Increase ◽  
Two Parameters ◽  
The Mathematical Model

Anchor dragging is a major threat to the structural integrity of submarine pipelines. A mathematical model in which the mechanical model of chain and the bearing model of anchor were coupled together. Based on the associated flow rule, an incremental procedure was proposed to solve the spatial state of anchor until it reaches the ultimate embedding depth. With an indirect measurement method for the anchor trajectory, a model test system was established. The mathematical model was validated against some model tests, and the effects of two parameters were studied. It was found that both the ultimate embedding depth of a dragging anchor and the distance it takes to reach the ultimate depth increase with the shank-fluke pivot angle, but decrease as the undrained shear strength of clay increases. The proposed model is supposed to be useful for the embedding depth calculation and guiding the design of the pipeline burial depth.

scholarly journals A comparative Analysis of PV Cell Mathematical Model

2021 ◽  
Vol 1795 (1) ◽  
pp. 012042
Author(s):  
M. Rasheed ◽  
O. Y. Mohammed ◽  
S. Shihab ◽  
Aqeel Al-Adili
Keyword(s):  
Mathematical Model ◽  
Comparative Analysis ◽  
Pv Cell

scholarly journals Content Dependent Representation Selection Model for Systems Based on MPEG DASH

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1843
Author(s):  
Jelena Vlaović ◽  
Snježana Rimac-Drlje ◽  
Drago Žagar
Keyword(s):  
Mathematical Model ◽  
Spatial Information ◽  
Relevant Literature ◽  
Video Quality ◽  
Similarity Index ◽  
Video Encoding ◽  
Adaptation Algorithm ◽  
Subjective Testing ◽  
Proposed Model ◽  
The Mathematical Model

A standard called MPEG Dynamic Adaptive Streaming over HTTP (MPEG DASH) ensures the interoperability between different streaming services and the highest possible video quality in changing network conditions. The solutions described in the available literature that focus on video segmentation are mostly proprietary, use a high amount of computational power, lack the methodology, model notation, information needed for reproduction, or do not consider the spatial and temporal activity of video sequences. This paper presents a new model for selecting optimal parameters and number of representations for video encoding and segmentation, based on a measure of the spatial and temporal activity of the video content. The model was developed for the H.264 encoder, using Structural Similarity Index Measure (SSIM) objective metrics as well as Spatial Information (SI) and Temporal Information (TI) as measures of video spatial and temporal activity. The methodology that we used to develop the mathematical model is also presented in detail so that it can be applied to adapt the mathematical model to another type of an encoder or a set of encoding parameters. The efficiency of the segmentation made by the proposed model was tested using the Basic Adaptation algorithm (BAA) and Segment Aware Rate Adaptation (SARA) algorithm as well as two different network scenarios. In comparison to the segmentation available in the relevant literature, the segmentation based on the proposed model obtains better SSIM values in 92% of cases and subjective testing showed that it achieves better results in 83.3% of cases.

A framework of decision making based on bipolar fuzzy competition hypergraphs

2021 ◽  
pp. 1-21
Author(s):  
Sundas Shahzadi ◽  
Areen Rasool ◽  
Musavarah Sarwar ◽  
Muhammad Akram
Keyword(s):  
Biological Sciences ◽  
Decision Making ◽  
Comparative Analysis ◽  
Social Networking ◽  
Real World ◽  
Fuzzy Models ◽  
New Concepts ◽  
Proposed Model ◽  
Business Market ◽  
Strength Of Competition

Bipolarity plays a key role in different domains such as technology, social networking and biological sciences for illustrating real-world phenomenon using bipolar fuzzy models. In this article, novel concepts of bipolar fuzzy competition hypergraphs are introduced and discuss the application of the proposed model. The main contribution is to illustrate different methods for the construction of bipolar fuzzy competition hypergraphs and their variants. Authors study various new concepts including bipolar fuzzy row hypergraphs, bipolar fuzzy column hypergraphs, bipolar fuzzy k-competition hypergraphs, bipolar fuzzy neighborhood hypergraphs and strong hyperedges. Besides, we develop some relations between bipolar fuzzy k-competition hypergraphs and bipolar fuzzy neighborhood hypergraphs. Moreover, authors design an algorithm to compute the strength of competition among companies in business market. A comparative analysis of the proposed model is discuss with the existing models such bipolar fuzzy competition graphs and fuzzy competition hypergraphs.

scholarly journals IMSC-EIoTD: Identity Management and Secure Communication for Edge IoT Devices

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6546
Author(s):  
Kazi Masum Sadique ◽  
Rahim Rahmani ◽  
Paul Johannesson
Keyword(s):  
Secure Communication ◽  
Identity Management ◽  
Security Protocols ◽  
Spin Model ◽  
The Internet ◽  
Human Society ◽  
Proposed Model ◽  
Authentication And Authorization ◽  
Quality Of Living ◽  
Iot Devices

The Internet of things (IoT) will accommodate several billions of devices to the Internet to enhance human society as well as to improve the quality of living. A huge number of sensors, actuators, gateways, servers, and related end-user applications will be connected to the Internet. All these entities require identities to communicate with each other. The communicating devices may have mobility and currently, the only main identity solution is IP based identity management which is not suitable for the authentication and authorization of the heterogeneous IoT devices. Sometimes devices and applications need to communicate in real-time to make decisions within very short times. Most of the recently proposed solutions for identity management are cloud-based. Those cloud-based identity management solutions are not feasible for heterogeneous IoT devices. In this paper, we have proposed an edge-fog based decentralized identity management and authentication solution for IoT devices (IoTD) and edge IoT gateways (EIoTG). We have also presented a secure communication protocol for communication between edge IoT devices and edge IoT gateways. The proposed security protocols are verified using Scyther formal verification tool, which is a popular tool for automated verification of security protocols. The proposed model is specified using the PROMELA language. SPIN model checker is used to confirm the specification of the proposed model. The results show different message flows without any error.

The Generation Principle and Mathematical Models of Double-Enveloping Internal Gear Pairs

2015 ◽  
Author(s):  
Xuan Li ◽  
Bingkui Chen ◽  
Yawen Wang ◽  
Guohua Sun ◽  
Teik C. Lim
Keyword(s):  
Mathematical Model ◽  
Load Capacity ◽  
Geometrical Shape ◽  
Gear Pair ◽  
Numerical Examples ◽  
Proposed Model ◽  
General Mathematical Model ◽  
Meshing Characteristics ◽  
Internal Gear ◽  
Tooth Pair

In this paper, the planar double-enveloping method is presented for the generation of tooth profiles of the internal gear pair for various applications, such as gerotors and gear reducers. The main characteristic of this method is the existence of double contact between one tooth pair such that the sealing property, the load capacity and the transmission precision can be significantly improved as compared to the conventional configuration by the single-enveloping theory. Firstly, the generation principle of the planar double-enveloping method is introduced. Based on the coordinate transformation and the envelope theory, the general mathematical model of the double-enveloping internal gear pair is presented. By using this model, users can directly design different geometrical shape profiles to obtain a double-enveloping internal gear pair with better meshing characteristics. Secondly, to validate the effectiveness of the proposed model, specific mathematical formulations of three double-enveloping internal gear pairs which apply circular, parabolic and elliptical curves as the generating curves are given. The equations of tooth profiles and meshing are derived and the composition of tooth profiles is analyzed. Finally, numerical examples are provided for an illustration.

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