Potential in microroughness domain of metal surface employed in cathodic protection mode

2021 ◽  
Vol 2021 (3) ◽  
pp. 48-54
Author(s):  
V. Lukovich ◽  
◽  
V. Kartuzov ◽  
Keyword(s):  
Mathematical Model ◽  
Metal Surface ◽  
Cathodic Protection ◽  
Computational Experiment ◽  
Computational Domain ◽  
Protective Potential ◽  
Long Time ◽  
Protection Mode ◽  
Model Equations ◽  
Iterative Procedures

This effort presents the results of investigation of cathodic protection process of a section of the main pipeline, which has been operating in cathodic protection mode for a long time and which insulation has completely exfoliated from metal surface, and a cavity between is filled with water and salt impurities. In this case, a decisive factor is a fact that a metal surface is covered with microroughnesses in the form of protrusions with almost conical shape. The surface is immersed in electrolyte. At the electrolyte-metal interface, a potential difference is formed - a corrosion potential, which creates an unstable equilibrium among the potentials of metal and electrolyte. A mathematical model is designed and implemented into a numerical algorithm and computer program. A computational experiment has been carried out to calculate the potential around microroughness. The model describes a change in potential in this area at incomplete and complete cathodic protection of metal surface. The basis of computational model is a selection of one of metal protrusions of material microheterogeneity and placing it in a cylinder, which diameter coincides with that one of the lower base of this protrusion, and its upper part passes through the apex of the protrusion. Mathematical model equations with corresponding boundary conditions and their discrete implementation are presented. The solution of problems is obtained by iterative procedures based on reference values of protective potential taken from practice. The results of computational experiment are presented in the form of graphs: 1) potential distribution in the field of electrolytes; 2) changes in electrolyte potential at the border with protrusion at different values of polarization potential; 3) changes in polarization resistance in the area (calculated). The geometry of computational domain was also varied, and the values of protective potential were determined to ensure the absence of corrosion. Keywords: corrosion, microroughness, protective potential, plastic current density, electrolyte

Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

2020 ◽  
Vol 10 (6) ◽  
pp. 599-609
Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Roughness Coefficient ◽  
Computational Domain ◽  
Channel Deformations ◽  
Geological Surveys ◽  
Kuban River ◽  
The Stability ◽  
Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

Research on cargo-loading optimization based on genetic and fuzzy integration

2021 ◽  
Vol 40 (4) ◽  
pp. 8493-8500
Author(s):  
Yanwei Du ◽  
Feng Chen ◽  
Xiaoyi Fan ◽  
Lei Zhang ◽  
Henggang Liang
Keyword(s):  
Genetic Algorithm ◽  
Mathematical Model ◽  
Three Dimensional ◽  
Distribution Center ◽  
Long Time ◽  
Low Efficiency ◽  
Decision Making Model ◽  
The Mathematical Model ◽  
Loading Scheme

With the increase of the number of loaded goods, the number of optional loading schemes will increase exponentially. It is a long time and low efficiency to determine the loading scheme with experience. Genetic algorithm is a search heuristic algorithm used to solve optimization in the field of computer science artificial intelligence. Genetic algorithm can effectively select the optimal loading scheme but unable to utilize weight and volume capacity of cargo and truck. In this paper, we propose hybrid Genetic and fuzzy logic based cargo-loading decision making model that focus on achieving maximum profit with maximum utilization of weight and volume capacity of cargo and truck. In this paper, first of all, the components of the problem of goods stowage in the distribution center are analyzed systematically, which lays the foundation for the reasonable classification of the problem of goods stowage and the establishment of the mathematical model of the problem of goods stowage. Secondly, the paper abstracts and defines the problem of goods loading in distribution center, establishes the mathematical model for the optimization of single car three-dimensional goods loading, and designs the genetic algorithm for solving the model. Finally, Matlab is used to solve the optimization model of cargo loading, and the good performance of the algorithm is verified by an example. From the performance evaluation analysis, proposed the hybrid system achieve better outcomes than the standard SA model, GA method, and TS strategy.

scholarly journals Study of Growth and Sublimation of Germanium Nitride Using the Concept of Tedmon's Kinetic Model

2020 ◽  
Vol 36 (05) ◽  
pp. 850-854
Author(s):  
Irakli Nakhutsrishvili
Keyword(s):  
Mathematical Model ◽  
Kinetic Model ◽  
Metal Surface ◽  
Kinetic Curve ◽  
Nitride Layer ◽  
Mass Change ◽  
Thermogravimetric Curve

The paper gives a mathematical model of a thermogravimetric curve for the growth of scale on a metal surface with its simultaneous sublimation is presented and considers the case of the growth-sublimation of scale being preceded by the process of gas etching of the monocrystal surface. The obtained equations are used to describe the kinetic curve of the mass change of a germanium sample when a nitride layer is formed on it in a medium of hydrazine vapors.

scholarly journals Analysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines

2017 ◽  
Vol 4 (2) ◽  
pp. 124-128 ◽  
Author(s):  
Iu. V. Murashov ◽  
V. Ya. Frolov ◽  
D. Uhrlandt ◽  
S. Gortschakow ◽  
D. V. Ivanov ◽  
...  
Keyword(s):  
Discharge Chamber ◽  
Three Dimensional ◽  
Plasma Temperature ◽  
Power Lines ◽  
Lightning Protection ◽  
Computational Domain ◽  
Transient Model ◽  
Electromagnetic Processes ◽  
Model Equations ◽  
Overhead Power Lines

Nowadays multi-chamber arresters are widely distributed as devices of lightning protection of overhead power lines. A mathematical modelling of processes in the discharge chamber of multichamber arrester is necessary to carry out in order to improve its breaking capacity. A three-dimensional mathematical transient model of thermal, gas-dynamic and electromagnetic processes taking place in the discharge chamber of multi-chamber arrester is presented in the article. Basic assumptions, model equations, a computational domain and the boundary conditions are described. Plasma turbulence is taken into account. The results of the calculation i.e. distributions of plasma temperature and overpressure in the discharge chamber at different time points are shown. The analysis of the results was carried out. It is shown that the presence of cavities in the electrodes design promotes electric arc extinction in the discharge chamber of multi-chamber arrester.

scholarly journals Mathematical Modeling and Analysis of Multirobot Cooperative Hunting Behaviors

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yong Song ◽  
Yibin Li ◽  
Caihong Li ◽  
Xin Ma
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Numerical Solutions ◽  
Rate Equations ◽  
Ratio Analysis ◽  
Hunting Behavior ◽  
Modeling And Analysis ◽  
Cooperative Hunting ◽  
Model Equations ◽  
The Mathematical Model

This paper presents a mathematical model of multirobot cooperative hunting behavior. Multiple robots try to search for and surround a prey. When a robot detects a prey it forms a following team. When another “searching” robot detects the same prey, the robots form a new following team. Until four robots have detected the same prey, the prey disappears from the simulation and the robots return to searching for other prey. If a following team fails to be joined by another robot within a certain time limit the team is disbanded and the robots return to searching state. The mathematical model is formulated by a set of rate equations. The evolution of robot collective hunting behaviors represents the transition between different states of robots. The complex collective hunting behavior emerges through local interaction. The paper presents numerical solutions to normalized versions of the model equations and provides both a steady state and a collaboration ratio analysis. The value of the delay time is shown through mathematical modeling to be a strong factor in the performance of the system as well as the relative numbers of the searching robots and the prey.

Solidification of a Binary Solution (NH4Cl+H2O) under Shear Flow: A Numerical Study

2014 ◽  
Vol 217-218 ◽  
pp. 174-181
Author(s):  
Akshaya Kumar Nayak ◽  
Nilkanta Barman ◽  
Himadri Chattaopadhyay
Keyword(s):  
Mathematical Model ◽  
Shear Flow ◽  
Numerical Study ◽  
Binary Solution ◽  
Species Conservation ◽  
Solidification Process ◽  
Bulk Solution ◽  
Computational Domain ◽  
Simpler Algorithm ◽  
Slurry Layer

In the present work, the solidification behaviour of a metal analogues transparent binary solution (8 wt% of NH4Cl in H2O) under shear flow is investigated numerically. The shear flow in the mush is developed due to flow over an inclined cooling plate. The dendrites formed during solidification are fragmented under the shear flow and transported into the bulk solution. The suspended dendrites form a slurry layer in the domain. Consequently, a suitable mathematical model is considered to study the transport phenomena. In the mathematical model, the free surface of the solution is represented by the volume-of-fluid (VOF) method. The solidification process is modelled by a set of volume-averaged-single-phase mass, momentum, energy and species conservation equations. A separate equation is considered for the solid velocity based on Stokes model. The governing equations are solved based on the pressure-based semi-implicit finite volume method according to the SIMPLER algorithm using TDMA solver along with the enthalpy update scheme. Finally, the simulation predicts temperature, velocity, solid fraction and the species distributions in the computational domain. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

Devices Used in Corrosion Control of Power Cables

CORROSION ◽  
1961 ◽  
Vol 17 (6) ◽  
pp. 300t-304t
Author(s):  
J. J. POKORNY
Keyword(s):  
Corrosion Protection ◽  
Cathodic Protection ◽  
Power Cables ◽  
Corrosion Control ◽  
Cable System ◽  
Long Time ◽  
Power Rectifier ◽  
Underground Power Cables ◽  
Test Current

Abstract This paper describes the various devices which are used in the corrosion control of underground power cables. Many of these devices have been used for a long time but the present paper describes a number of useful improvements in such devices as the electrolysis switch, the test current interrupter, and the cathodic protection and forced drainage rectifiers. The use of silicon power rectifier as an electrolysis switch is described. A method of grounding and corrosion protection of a pipe cable system is also outlined. 7.7, 5.2.1

Transport in Cathode of Lithium-Ion Cells

2006 ◽  
Vol 517 ◽  
pp. 101-104 ◽  
Author(s):  
Siti Aishah Hashim Ali
Keyword(s):  
Mathematical Model ◽  
Analytical Solutions ◽  
Lithium Ion ◽  
Cell Voltage ◽  
Voltage Versus ◽  
Discharge Characteristics ◽  
Lithium Ion Cells ◽  
Lithium Ion Cell ◽  
Model Equations ◽  
Discharge Curves

A mathematical model for the transport in cathode of a lithium-ion cell is developed and analytical solutions to the model equations are obtained. The derived equation is tested by fitting it to published experimental discharge characteristics. Wherever possible, the values of the relevant parameters are obtained from the same literature from which the discharge characteristics were obtained. The agreement between the predicted and the experimental discharge curves are measured statistically using t-test. Since the discharge characteristics are usually plotted as voltage versus time or capacity or even state-of-discharge, hence the expression for the cell voltage has been derived.

INTERNAL BALLISTICS OF CLASSIC GUN WITH COMPOSITE CHARGE

2019 ◽  
Vol 147 (3/2018) ◽  
pp. 47-62
Author(s):  
Marek Radomski
Keyword(s):  
Mathematical Model ◽  
Hard Core ◽  
Combustion Products ◽  
Maximum Pressure ◽  
Muzzle Velocity ◽  
Internal Ballistics ◽  
Lumped Parameter ◽  
Model Equations ◽  
Gun Firing ◽  
Composite Charge

The paper presents a lumped parameter mathematical model considering the changes of thermodynamic properties for combustion products of a composite propelling charge, and of a burning cartridge casing or shell as well, when shot with classic guns. In addition a method was proposed for considering not coincidental instants of ignition for particular components of the charge and also for powder grains of each component, and the heat flow into the walls containing the space with combustion products. Some results of numerical computations are shown for 125 mm 2A46 tank gun firing a hard core projectile. Moreover an evaluation of accuracy of the results is given on the basis of experimental data. Maximum pressure and muzzle velocity were basic criteria at the verification of the model. Analysis of accuracy for solutions of model equations allows a conclusion that the proposed mathematical model may be useful at the designing process of ammunition and guns.

scholarly journals Fluid dilution and efficiency of Na+ transport in a mathematical model of a thick ascending limb cell

2013 ◽  
Vol 304 (6) ◽  
pp. F634-F652 ◽  
Author(s):  
Aniel Nieves-González ◽  
Chris Clausen ◽  
Mariano Marcano ◽  
Anita T. Layton ◽  
Harold E. Layton ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Cell Model ◽  
Cell Volume Regulation ◽  
Mass Conservation ◽  
Thick Ascending Limb ◽  
Outer Medulla ◽  
Transport Efficiency ◽  
Nacl Concentration ◽  
Model Equations ◽  
Static Head

Thick ascending limb (TAL) cells are capable of reducing tubular fluid Na+ concentration to as low as ∼25 mM, and yet they are thought to transport Na+ efficiently owing to passive paracellular Na+ absorption. Transport efficiency in the TAL is of particular importance in the outer medulla where O2 availability is limited by low blood flow. We used a mathematical model of a TAL cell to estimate the efficiency of Na+ transport and to examine how tubular dilution and cell volume regulation influence transport efficiency. The TAL cell model represents 13 major solutes and the associated transporters and channels; model equations are based on mass conservation and electroneutrality constraints. We analyzed TAL transport in cells with conditions relevant to the inner stripe of the outer medulla, the cortico-medullary junction, and the distal cortical TAL. At each location Na+ transport efficiency was computed as functions of changes in luminal NaCl concentration ([NaCl]), [K+], [NH4+], junctional Na+ permeability, and apical K+ permeability. Na+ transport efficiency was calculated as the ratio of total net Na+ transport to transcellular Na+ transport. Transport efficiency is predicted to be highest at the cortico-medullary boundary where the transepithelial Na+ gradient is the smallest. Transport efficiency is lowest in the cortex where luminal [NaCl] approaches static head.

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