A Permeable Coating Model for Predicting the Environment at the Pipe Surface Under CP-Compatible Coatings

2004 ◽  
Author(s):  
Fraser King ◽  
Tom Jack ◽  
Miroslav Kolar ◽  
Robert Worthingham
Keyword(s):  
Mathematical Model ◽  
Field Data ◽  
Coal Tar ◽  
Local Environment ◽  
Electrochemical Reactions ◽  
Underground Pipeline ◽  
Pipe Surface ◽  
Pass Through ◽  
Surrounding Soil ◽  
Surface Generate

Some underground pipeline coatings, such as asphalt, coal tar enamel and fusion-bonded epoxy, are said to be CP-compatible. When these coatings degrade and groundwater contacts the pipe, the surface is still protected from corrosion and stress corrosion cracking (SCC) as the CP current can pass through the permeable coating. The electrochemical reactions on the pipe surface generate a local environment under the coating that is quite different from that in the surrounding soil. In general, the pH of the trapped water increases due to the cathodic reduction of water and oxygen by the CP current. A mathematical model has been developed to predict the generation and evolution of the environment under a disbonded permeable coating as a consequence of the action of CP. The model couples the electrochemical reactions on the surface of the pipe to the transport of species to and from the pipe surface through the permeable coating and the surrounding soil. The model is structured to use available field data (such as soil and ground water data and information from CP surveys) to predict conditions on the pipe surface. The model can be used to predict CP and environmental conditions under which the pipe may be susceptible to corrosion or SCC.

Network analysis models – the secret for success

2004 ◽  
Vol 4 (5-6) ◽  
pp. 383-388
Author(s):  
D.M. Rogers
Keyword(s):  
Mathematical Model ◽  
Field Data ◽  
Essential Element ◽  
Distribution Networks ◽  
Automatic Calibration ◽  
Supply And Distribution ◽  
The World ◽  
Optimum Approach ◽  
Analysis Models

Water is a fundamental necessity of life. Yet water supply and distribution networks the world over are old and lacking in adequate maintenance. Consequently they often leak as much water as they deliver and provide an unacceptable quality of service to the customer. In certain parts of the world, water is available only for a few hours of the day. The solution is to build a mathematical model to simulate the operation of the real network in all of its key elements and apply it to optimise its operation. To be of value, the results of the model must be compared with field data. This process is known as calibration and is an essential element in the construction of an accurate model. This paper outlines the optimum approach to building and calibrating a mathematical model and how it can be applied to automatic calibration systems.

Soil Persistence of Dinitramine

Weed Science ◽  
1980 ◽  
Vol 28 (6) ◽  
pp. 650-654 ◽  
Author(s):  
J. A. Poku ◽  
R. L. Zimdahl
Keyword(s):  
Mathematical Model ◽  
Soil Moisture ◽  
Field Data ◽  
Soil Moisture Content ◽  
Sandy Loam ◽  
Clay Loam ◽  
First Order ◽  
Soil Persistence ◽  
Herbicide Concentration ◽  
Increasing Temperature

The effects of soil temperature, moisture, and herbicide concentration on the rate of degradation of dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) were measured in clay loam and sandy loam in the laboratory. In sandy loam, the rate of degradation increased with increasing temperature. In clay loam, the rate of degradation increased from 10 to 30 C and decreased at 40 C. Soil moisture content influenced the rate of degradation in the following order: 22>11>>2.2% (air-dry) for clay loam and 12.0 = 6.0>>0.5% (air-dry) for sandy loam. First-order half-lives ranged from 3.2 at 30 C to 47 weeks at 10 C in clay loam, and 2.3 at 40 C to 31 weeks at 10 C in sandy loam. Applications in 2 yr did not cause buildup of dinitramine in the field. A mathematical model was used in an attempt to correlate laboratory and field data.

scholarly journals Introducing a particular mathematical model for predicting the resistance and performance of prismatic planing hulls in calm water by means of total pressure distribution

2015 ◽  
Vol 12 (2) ◽  
pp. 73-94 ◽  
Author(s):  
P. Ghadimi ◽  
S. Tavakoli ◽  
M. A. Feizi Chekab ◽  
A. Dashtimanesh
Keyword(s):  
Mathematical Model ◽  
Pressure Distribution ◽  
Total Pressure ◽  
Center Of Gravity ◽  
Governing Equations ◽  
Calm Water ◽  
Hydrodynamic Study ◽  
Pass Through ◽  
And Performance

Mathematical modeling of planing hulls and determination of their characteristics are the most important subjects in hydrodynamic study of planing vessels. In this paper, a new mathematical model has been developed based on pressure distribution. This model has been provided for two different situations: (1) for a situation in which all forces pass through the center of gravity and (2) for a situation in which forces don not necessarily pass through the center of gravity. Two algorithms have been designed for the governing equations. Computational results have been presented in the form of trim angle, total pressure, hydrodynamic and hydrostatic lift coefficients, spray apex and total resistance which includes frictional, spray and induced resistances. Accuracy of the model has been verified by comparing the numerical findings against the results of Savitsky's method and available experimental data. Good accuracy is displayed. Furthermore, effects of deadrise angle on trim angle of the craft, position of spray apex and resistance have been investigated.

Application of mathematical model for the process of coal tar pitch modified petroleum asphalt

2018 ◽  
Vol 41 (14) ◽  
pp. 1752-1761
Author(s):  
Yongbing Xue ◽  
Shixin Li ◽  
Zefeng Ge ◽  
Fengchao Li ◽  
Zhenmin Liu
Keyword(s):  
Mathematical Model ◽  
Coal Tar ◽  
Coal Tar Pitch ◽  
Petroleum Asphalt

POPILLIA JAPONICA (COLEOPTERA: SCARABAEIDAE): A MATHEMATICAL MODEL OF OVIPOSITION IN HETEROGENEOUS AGROECOSYSTEMS

1979 ◽  
Vol 111 (11) ◽  
pp. 1271-1280 ◽  
Author(s):  
Jacques Régnière ◽  
Robert L. Rabb ◽  
R. E. Stinner
Keyword(s):  
Mathematical Model ◽  
Pest Management ◽  
Field Data ◽  
Food Source ◽  
The State ◽  
Soil Conditions ◽  
Popillia Japonica ◽  
Japanese Beetle ◽  
Potential Applications

AbstractA mathematical model is developed which simulates the effect of the number of eggs in females, food source, and soil conditions, on ovogenesis and oviposition of Japanese beetle populations. The number of eggs in females is used as the state indicator, and simulated trends are compared to field data. Potential applications in pest management are discussed.

scholarly journals Measuring the net outcome of conditional mutualism: a case study with oaks and scatterhoarding rodents

2017 ◽  
Author(s):  
Michał Bogdziewicz ◽  
Elizabeth E. Crone ◽  
Rafał Zwolak
Keyword(s):  
Mathematical Model ◽  
Seed Predation ◽  
Short Distance ◽  
Field Data ◽  
Seedling Recruitment ◽  
Quercus Petraea ◽  
Simple Mathematical Model ◽  
Vital Rates ◽  
Plant Establishment

AbstractNumerous interactions between plants and animals vary in their outcome between antagonism and mutualism, but it has proven to be difficult to quantify their final outcome. Interactions between plants and scatterhoarding animals provide a prime example of this phenomenon. Scatterhoarders consume large quantities of seeds (potentially reducing plant establishment), yet also disperse seeds and bury them in shallow caches (potentially improving recruitment). However, it has been rarely determined which role prevails for particular plant species. We demonstrate how plant-scatterhoarder interactions can be placed at the antagonism-mutualism continuum, with interactions between rodents and two oaks species (sessile oak Quercus petraea, and red oak Q. rubra) as an empirical example. Our approach consists of quantifying the net outcome of the interaction through assembling different vital rates (e.g. probability of seedling recruitment with and without rodents; near and far from conspecific trees; with and without seed pilferage) piecewise with a simple mathematical model. Our results indicate that during the period of the study, interactions between scatterhoarding rodents and both focal oaks were antagonistic. Even though acorn burial increased the likelihood of seedling establishment, this effect was not strong enough to compensate for the costs of seed predation. Furthermore, we found no evidence that the short-distance transportation that is usually provided by small mammals benefited early oak recruitment. Our study demonstrates how readily accessible field data can be used to gauge the outcomes in conditional mutualisms.

All-mode Validation of Calculations in the Analysis of Electric Power

2020 ◽  
Vol 11 (11) ◽  
pp. 28-37
Author(s):  
Aleksey A. SUVOROV ◽  
◽  
Alexander S. GUSEV ◽  
Mikhail V. ANDREEV ◽  
Alisher B. ASKAROV ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Power System ◽  
Electric Power ◽  
Field Data ◽  
Transient Stability ◽  
Experimental Studies ◽  
Electric Power System ◽  
Adequate Model ◽  
Simulation Results

The transient stability is the main condition for reliability and survivability operation of electric power system. The transient stability analysis is an extremely complex problem. It uses the results of numerical integration of differential equations that form a mathematical model of the power system. However, the mathematical model of a large-scale power system contains a rigid nonlinear system of extremely high-order differential equations. Such system cannot be solved analytically. The simplifications and limitations are used for improving the conditionality of the power system mathematical model in time-domain simulation. It decreases the reliability and accuracy of the simulation results. In this regard, it becomes necessary to validate them. The most reliable way of validation is to compare simulation results with field data. However, it is not always possible to receive the necessary amount of field data due to many power system states and a large amount of disturbances leading to instability. The paper proposes an alternative approach for validation: using an adequate model standard instead of field data. The prototype of Hybrid Real Time Power System Simulator having the necessary properties and capabilities has been used as the reference model. The appropriate sequence of actions has been developed for validation. The adequacy of proposed approach is illustrated by the fragments of the experimental studies

Finite Element Thermal Analysis on Heat Transfer Performance of Rectangular Micro – Groove Flat Heat Pipe

2013 ◽  
Vol 721 ◽  
pp. 456-460
Author(s):  
Yi Bing Liu
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Analysis ◽  
Heat Pipe ◽  
Heat Transfer Process ◽  
Pipe Surface ◽  
Iterative Computation ◽  
Flow And Heat Transfer ◽  
The Mathematical Model ◽  
Flat Heat Pipe

Having fully considered the influence of gas-liquid interfacial friction on the heat transfer characteristics of heat pipe within the channel, the mathematical model of the flow and heat transfer process in the Rectangular Micro-groove flat heat pipe is established. The simulation is performed by using thermal analysis software ANSYS. The iterative computation values of the center point temperature of the heat pipe surface being compared with the simulation results, the error is only 5.27% and the two are basically the same values, which shows that the mathematical model has a guiding significance on the analysis of heat pipe theory.

A MATHEMATICAL MODEL FOR CELL-INDUCED GEL COMPACTION IN VITRO

2012 ◽  
Vol 23 (01) ◽  
pp. 127-163 ◽  
Author(s):  
J. E. F. GREEN ◽  
ANDREW P. BASSOM ◽  
AVNER FRIEDMAN
Keyword(s):  
Mathematical Model ◽  
Early Time ◽  
Local Environment ◽  
Force Balance ◽  
Collagen Gels ◽  
Compressible Viscous Fluid ◽  
State Behavior ◽  
Density Relation ◽  
Experimental Findings

We present a mathematical model for cell-induced gel contraction in vitro. The core of the model consists of conservation equations for the mass of the gel and the number of cells, coupled to a force balance on the gel. On the basis of previously reported experimental findings for collagen gels, which are frequently used experimentally, the gel is treated as a compressible viscous fluid while inertial effects are neglected. The flow is assumed to be isothermal, and a linear pressure–density relation is adopted. The force exerted on the gel by cells is assumed to depend upon the local environment surrounding the cell: influences can include the cell and extracellular matrix density, and the concentration of a diffusible chemical produced by the cells. We consider the simple, but experimentally relevant, case of spherically symmetric gels. For cell-free gels, we show how simple experiments might be used to determine the parameters in the model. When the cell-derived forces are given by a prescribed function of position, we are able to obtain the early time and steady-state behavior of the solution analytically. We perform numerical simulations which generate predictions of how the gel density evolves during compaction under differing assumptions concerning the factors influencing the force exerted by the cells. These results are compared with some previous observations reported in the literature.

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