scholarly journals MATHEMATICAL MODELING OF RESIDUAL STRESSES IN PLASMA COATINGS TAKING INTO ACCOUNT THE PROCESS OF INCREASING LAYERS

2020 ◽  
Vol 22 (6) ◽  
pp. 14-20
Author(s):  
V.I. Bogdanovich ◽  
◽  
M.G. Giorbelidze ◽  
I.A. Dokukina ◽  
N.V. Surkova ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Residual Stresses ◽  
Mathematical Models ◽  
Ambient Temperature ◽  
Experimental Studies ◽  
Final Temperature ◽  
Good Convergence ◽  
Plasma Coatings

Developed a mathematical model for determining residual stresses with increasing plasma coatings, taking into account the stresses arising upon cooling of the material from the final temperature to ambient temperature; tension that arises when removing the fastening devices and tension that existed in the substrate before spraying. The developed mathematical models are adapted for the most common cases of fixing the base used in the practice of coating. Experimental studies of residual stresses were carried out, which showed good convergence with the values of residual stresses obtained theoretically.

Adsorption-Desorption Processes in Adsorption Chillers

2016 ◽  
Vol 20 (2) ◽  
pp. 81-89
Author(s):  
Monika Gwadera
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Experimental Studies ◽  
Operating Principle ◽  
Adsorption Desorption ◽  
The Mathematical Model

AbstractThe aim of this paper is to present the adsorption chillers technology. The operating principle of these systems, the adsorbent-adsorbate pairs that are frequently applied and the enhancement techniques that allow improvement of their efficiency are presented. Analysis of the mass transfer and principles of mathematical modeling of such systems are also discussed. In the further part of the text, the results of experimental studies and comparison of these results with calculations based on the mathematical model of adsorption were presented.

scholarly journals Mathematical modeling in economics for selection of optimum investment solution

2021 ◽  
Vol 273 ◽  
pp. 08003
Author(s):  
Arthur Alukhanyan ◽  
Olga Panfilova
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Linear Programming ◽  
Mathematical Models ◽  
Programming Problem ◽  
Linear Programming Problem ◽  
Target Function ◽  
Investment Portfolio ◽  
Monetary Relations ◽  
Selection Of

This work is devoted to development of economic and mathematical models for selection of the optimum investment solution. Moreover, it states the basis for development of model examples and correction of the model considering the results obtained in the examples. In the work the problem is set for selection of the investment sources and objects, which is limited to the linear programming problem. The controlled variable and basic limitations simulating real credit and monetary relations are distinguished in the provided model. The discounted profit obtained from implementation of the optimum investment portfolio is considered as a target function. The economic and mathematical model presented in the article allows finding the optimum investment solution within the limits of the credit and monetary relations taking place both at the micro- and macroeconomic level.

scholarly journals Mathematical modeling of the corpse cooling under conditions of varying ambient temperature

2021 ◽  
Vol 7 (1) ◽  
pp. 29-35
Author(s):  
German V. Nedugov
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Ambient Temperature ◽  
Analytical Determination ◽  
Time Of Death ◽  
Main Condition ◽  
Proposed Model ◽  
Thermometric Determination ◽  
Early Postmortem

Background: The constancy of the ambient temperature is the main condition to correctly determine the time of death by thermometric method. However, in practice, this requirement is met only in cases of death in closed rooms. In this study, an exponential mathematical model was proposed for corpse cooling under any changes in ambient temperature. Aim: This study aimed to develop a mathematical model to determine the time of death based on the NewtonRichman cooling law in changing ambient temperature conditions. Materials and methods: Mathematical modeling of corpse cooling under changing ambient temperature is performed, focusing on problem solving of thermometric determination of the time of death. The axillary hollow was used as the diagnostic zone of the corpse, and the temperature of which at the time of death is taken is 36.6С. Results: A method of reverse reproduction of the cadaver temperature in conditions of changing ambient temperature has been developed. Results allow a relatively simple analytical determination of the time of death in the early postmortem period. Conclusions: The proposed method is advisable to be used in forensic medical practice to determine the time of death in early postmortem period. The developed mathematical model is implemented in the format of the application program Warm Bodies NRN. Use of tympanic and intraocular thermometry was recommended within the proposed model.

A Mathematical Analysis of Directional Solidification of Aqueous Solutions

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Gideon Ukpai ◽  
Boris Rubinsky
Keyword(s):  
Mathematical Model ◽  
Aqueous Solutions ◽  
Mathematical Models ◽  
Directional Solidification ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Design Parameters ◽  
Fundamental Study ◽  
Biological Matter ◽  
Intent To Use

Abstract Horizontal directional solidification techniques have been broadly utilized for the freezing of biological matter under conditions in which the freezing rate during solidification must be controlled and known. Directional solidification is used for diverse applications such as fundamental research on freezing of biological materials, cryopreservation of biological matter, and tissue engineering. This study is motivated by our intent to use directional solidification as a simplified model for the study of three-dimensional (3D) cryoprinting. In evaluating directional solidification in the context of 3D cryoprinting, we realized that current mathematical models of directional solidification are not adequately representative for this purpose, because they are simplified and one-dimensional (1D). Here, we introduce an experimentally verified and more representative two-dimensional (2D) mathematical model of directional solidification that can aid in the fundamental study of freezing of biological matter, in particular during 3D cryoprinting. The mathematical model was used to develop correlations between the freezing rates that a layer of an aqueous solution experiences during directional solidification and the various design parameters such as thickness of the sample and temperature gradients in the substrate. Results show that the freezing rates can be higher than those suggested by the previously used simplified 1D mathematical models. The results can be used for developing simplified models of 3D cryoprinting. In addition, the results suggest that many experimental studies on directional solidification of aqueous solutions and biological matter may require readjustment of analysis, in view of these findings.

INFLUENCE OF DYNAMIC LOADING ON THE CHARACTERISTICS OF POLYMER IMPACT DAMPERS

2020 ◽  
Author(s):  
Vladimir Altuhov ◽  
Aleksey Boldyrev ◽  
Pavel Zhirov
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Ambient Temperature ◽  
Dynamic Loading ◽  
Loading Rate ◽  
Rolling Stock ◽  
Wear Factor ◽  
Shock Absorbers ◽  
Draft Gear ◽  
Freight Car

The article is devoted to the study of the influence of dynamic loading on the characteristics of polymer elements of shock absorbers of the rolling stock of railways and to the description of the creation of a mathematical model of their work. The results of mathematical modeling are further used to solve problems of the longitudinal dynamics of rolling stock. In the study, the initial loading rate varied, the ambient temperature and the influence of the wear factor remained unchanged. For the operating speeds of a freight car, a mathematical model of the PMKP-110 draft gear was determined.

Mathematical Modeling of the Anaerobic Filter Process

1983 ◽  
Vol 15 (8-9) ◽  
pp. 197-207 ◽  
Author(s):  
M Lindgren
Keyword(s):  
Mathematical Modeling ◽  
Waste Water ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Efficient Tool ◽  
Anaerobic Filter ◽  
Filter Process

A dilute synthetic waste water was anaerobica1ly treated in a filter. A mathematical model of the anaerobic filter process was also developed and analyzed. Analysis showed that mathematical models are an efficient tool for system understanding and design.

scholarly journals A Mathematical Model for Top Nutation Based on Inertial Forces of Distributed Masses

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ryspek Usubamatov ◽  
Albina Omorova
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Angular Momentum ◽  
Mathematical Models ◽  
Vibration Analysis ◽  
Analytical Approach ◽  
Main Property ◽  
Inertial Forces ◽  
Applied Torque ◽  
Dynamics And Vibration

The main property of gyroscopic devices is maintaining the axis of a spinning rotor, a mathematical model formulated on the principle of the change in the angular momentum. This principle is used for mathematical modeling of the motions of a top at known publications. Nevertheless, practical tests of gyroscopic devices do not correspond to this analytical approach. Recent investigations have demonstrated that the origin of gyroscope properties is more complex than that represented in known publications. The applied torque on a gyroscope produces internal torques of the spinning rotor based on the action of the several inertial forces. These forces are the centrifugal, Coriolis, and common inertial forces as well as the change in the angular momentum generated by the mass elements and center-mass of the spinning rotor. The action of these torques manifests itself in the resistance and precession torques of the gyroscopic devices. These inertial torques act simultaneously and interdependently around two axes and represent the fundamental principles of the gyroscope theory. The new inertial torques enable deriving mathematical models for the motions of well-known top that is the simplest form of gyroscopic devices. The novelty of the work is mathematical models for the motions of the top based on action of eight inertial forces acting around its two axes. The obtained mathematical models for the top nutation and self-stabilization are represented in terms of machine dynamics and vibration analysis. The new analytical approach for motions of the well-balanced top and top with eccentricity of the center-mass definitely responds to the practical results.

Mathematical Modeling of Biofilms

1997 ◽  
Vol 11 (1) ◽  
pp. 127-132 ◽  
Author(s):  
George H. Dibdin
Keyword(s):  
Mathematical Modeling ◽  
Complex System ◽  
Mathematical Model ◽  
Numerical Methods ◽  
Mathematical Models ◽  
Diffusion Coefficients ◽  
Theoretical Basis ◽  
Reversible Reaction ◽  
Mathematical Equations ◽  
Insight Into

A set of mathematical equations constitutes a mathematical model if it aims to represent a real system and is based on some theory of that system's operation. On this definition, mathematical models, some very simple, are everywhere in science. A complex system like a biofilm requires modeling by numerical methods and, because of inevitable uncertainties in its theoretical basis, may not be able to make precise predictions. Nevertheless, such models almost always give new insight into the mechanisms involved, and stimulate further investigation. The way in which diffusion coefficients are measured for use in a model, particularly whether they include effects of reversible reaction, is a key element in the modeling. Reasons are given for separating diffusion from reversible reaction effects and dealing with them in a separate subroutine of the model.

scholarly journals Mathematical Modeling to Perform an Analysis of Social Isolation Periods in the Dissemination of COVID-19

2021 ◽  
Vol 22 (4) ◽  
pp. 595-608
Author(s):  
A. Molter ◽  
R. S. Quadros ◽  
M. Rafikov ◽  
D. Buske ◽  
G. A. Gonçalves
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Social Isolation ◽  
Computer Simulations ◽  
The Other ◽  
Stable Level ◽  
The Social ◽  
The World ◽  
Second Peak

The outbreak of COVID-19 has made scientists from all over the world do not measureefforts to understand the dynamics of the disease caused by this coronavirus. Several mathematical models have been proposed to describe the dynamics and make predictions. This work proposes a mathematical model that includes social isolation of susceptible individuals as a strategy of suppression and mitigation of the disease. The Susceptible-Infectious-Isolated-Recovered-Dead (SIQRD) model is proposed to analyze three important issues about the dynamics of the disease taking into account social isolation: when the isolation should begin? How long to keep the isolation? How to get out of this isolation? To get answers, computer simulations are provided and their results discussed. The results obtained show that beginning social isolation on the 10th or 15th days, after confirmation of the 50th case, and with 70% of the population in isolation, seems to be promising, since the infected curve does not grow much until it enters the isolation and remains at a stable level during the isolation. On the other hand an abrupt release of the social isolation will imply a second peak of infected individuals above the first one, which is not desired. Therefore, the release from social isolation should be gradual.

scholarly journals METHODOLOGY OF DEVELOPMENT OF MATHEMATICAL MODELS OF INFORMATION PROCESSING SYSTEMS

2021 ◽  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Information System ◽  
Information Processing ◽  
Mathematical Models ◽  
System Approach ◽  
Research Method ◽  
Literary Sources ◽  
History Of ◽  
The Mathematical Model

Modeling as a research method is a powerful cognitive tool throughout the history of human development. The article describes the methodology for the development of mathematical models of information systems, based on materials from various literary sources, author's developments on the system approach, mathematical modeling and programming. The mathematical model of the information system is described and all the characteristics of the IS are given.

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