scholarly journals Bioeconomic-Epidemiological Model of Scomber colias Population in the Moroccan Coasts

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Nossaiba Baba ◽  
Imane Agmour ◽  
Yousef El Foutayeni ◽  
Naceur Achtaich
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Maximum Principle ◽  
High Yield ◽  
Bioeconomic Model ◽  
Thunnus Thynnus ◽  
The Maximum Principle ◽  
Parasitic Helminths ◽  
Scomber Colias ◽  
Infected Prey

In this paper, we develop and study a mathematical model for the dynamics of Scomber colias and Thunnus thynnus prey-predator with parasitic helminths. We search to analyze a bioeconomic model in which both susceptible and infected prey populations Scomber colias are exposed to the predator Thunnus thynnus, with varying degrees of exposure. However, the predator feeds preferentially on the most numerous prey types. This implies a kind of switching from the susceptible class to the infected class, and vice versa, as these two types of prey change in numerical superiority. So, the positivity, boundedness, equilibria, stability, and bioeconomic equilibrium are studied. Some numerical simulation of stability is cited. For giving a high yield and keeping the Scomber colias and Thunnus thynnus populations away from extension, we use the Maximum Principle of Pontryagin.

3D Numerical Simulation for Reinforcement of Jijiata Tunnel, Liulin County, Shanxi Province

2011 ◽  
Vol 368-373 ◽  
pp. 1064-1068
Author(s):  
Chang Liang Zhang ◽  
Shang Jin Huang ◽  
Jian Tao Guo ◽  
Tong Lu Li
Keyword(s):  
Numerical Simulation ◽  
Maximum Principle ◽  
Structural Damage ◽  
Lateral Displacement ◽  
Minimum Principle ◽  
Surrounding Rock ◽  
Shanxi Province ◽  
Tension Stress ◽  
3D Numerical Simulation ◽  
The Maximum Principle

In this paper, the deformations and the stresses of surrounding rock of Jijiata tunnel, Liulin County, Shanxi Province, are all computed before reinforcement and after reinforcement, through the 3D numerical simulation. According to the computing result, before reinforcement, the computing result of the lateral displacements of the surrounding rock is consistent with the field measurement result. The maximum principle stress and the minimum principle stress are all less than the strength of the surrounding rock supporting, and this will not cause material damage so as to structural damage. But, since the tension stress is higher than the strength of the junction of tunnel arch and tunnel upright wall, this leads the larger deformation and the failure of the junction. After reinforcement, through the steel arch and the lock pin bolt’s enhanced role, the lateral displacement of the tunnel can be constrained effectively, the maximum principle stress and the minimum principle stress can be less than the strength of the surrounding rock supporting, and the tension stress can also be less than the strength of the junction. All the structures are all stable after reinforcement. Thus, this method should be selected as the proper method to reinforce the tunnel.

The Optimal Form of Shallow Shells of Revolution with a Small Flexible Stiffness

2014 ◽  
Vol 988 ◽  
pp. 367-370
Author(s):  
Leonid U. Stupishin ◽  
Sergey Emelyanov ◽  
Maksim U. Pereverzev ◽  
Maria L. Moshkevich
Keyword(s):  
Mathematical Model ◽  
Maximum Principle ◽  
Optimal Design ◽  
Shells Of Revolution ◽  
Shallow Shells ◽  
Optimal Form ◽  
The Maximum Principle ◽  
The Mathematical Model ◽  
Made In

An important aspect of the theory of optimal design of shells is a question technology of determination of optimal forms of shells with numerical methods, based on the variation definitions. The distribution of effort in sloping shell of revolution optimal form, uniformly loaded with despens intensity is analyzed. The mathematical model of shell optimal form is based on the maximum principle of L.S. Pontryagin. The solution of the objective is numerically made in MathCad. The relations of the distribution of the longitudinal forces and moments along the radius of the shell is shown.

Numerical Simulation on Mold Electromagnetic Eccentric Stirring and Central Segregation of Round Bloom

2013 ◽  
Vol 652-654 ◽  
pp. 2450-2454
Author(s):  
Zhi Hong Zhang ◽  
Guo Guang Cheng
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Electromagnetic Stirring ◽  
Center Line ◽  
Central Segregation

The paper describes multi-section round bloom casting using external MEMS, equipped with max section D600mm and min D280mm mold, the center line of D280mm mold not coincident with the axis of stirrer coils. it is exist eccentric electromagnetic stirring of mold which section less than max D600mm, a mathematical model of MEMS has been established, the index of central segregation of D280mm macrostructure had decreased less than 1.12 by optimized parameters of electromagnetic stirring and SEN immerse depth, in the end, the quality of round bloom had improved.

scholarly journals Local versus nonlocal elliptic equations: short-long range field interactions

2020 ◽  
Vol 10 (1) ◽  
pp. 895-921
Author(s):  
Daniele Cassani ◽  
Luca Vilasi ◽  
Youjun Wang
Keyword(s):  
Asymptotic Behavior ◽  
Maximum Principle ◽  
Weak Solutions ◽  
Elliptic Equations ◽  
Spectral Properties ◽  
Fractional Laplacian ◽  
Coupling Parameter ◽  
Nonlocal Operators ◽  
The Maximum Principle ◽  
Regularity Results

Abstract In this paper we study a class of one-parameter family of elliptic equations which combines local and nonlocal operators, namely the Laplacian and the fractional Laplacian. We analyze spectral properties, establish the validity of the maximum principle, prove existence, nonexistence, symmetry and regularity results for weak solutions. The asymptotic behavior of weak solutions as the coupling parameter vanishes (which turns the problem into a purely nonlocal one) or goes to infinity (reducing the problem to the classical semilinear Laplace equation) is also investigated.

scholarly journals Regularized Asymptotics of the Solution of the Singularly Perturbed First Boundary Value Problem on the Semiaxis for a Parabolic Equation with a Rational “Simple” Turning Point

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 405
Author(s):  
Alexander Yeliseev ◽  
Tatiana Ratnikova ◽  
Daria Shaposhnikova
Keyword(s):  
Parabolic Equation ◽  
Maximum Principle ◽  
Boundary Value Problem ◽  
Regularization Method ◽  
Turning Point ◽  
Boundary Value ◽  
Singularly Perturbed ◽  
Asymptotic Convergence ◽  
The Maximum Principle ◽  
Regularized Asymptotics

The aim of this study is to develop a regularization method for boundary value problems for a parabolic equation. A singularly perturbed boundary value problem on the semiaxis is considered in the case of a “simple” rational turning point. To prove the asymptotic convergence of the series, the maximum principle is used.

Optimal Control of a General Environmental Space

1986 ◽  
Vol 108 (4) ◽  
pp. 330-339 ◽  
Author(s):  
M. A. Townsend ◽  
D. B. Cherchas ◽  
A. Abdelmessih
Keyword(s):  
Optimal Control ◽  
Maximum Principle ◽  
Moisture Content ◽  
Control Strategies ◽  
Switching Control ◽  
The Maximum Principle ◽  
Environmental Space ◽  
And Performance

This study considers the optimal control of dry bulb temperature and moisture content in a single zone, to be accomplished in such a way as to be implementable in any zone of a multi-zone system. Optimality is determined in terms of appropriate cost and performance functions and subject to practical limits using the maximum principle. Several candidate optimal control strategies are investigated. It is shown that a bang-bang switching control which is theoretically periodic is a least cost practical control. In addition, specific attributes of this class of problem are explored.

ASYMPTOTIC DECAY TOWARD THE PLANAR RAREFACTION WAVES FOR A MODEL SYSTEM OF THE RADIATING GAS IN TWO DIMENSIONS

2008 ◽  
Vol 18 (04) ◽  
pp. 511-541 ◽  
Author(s):  
WENLIANG GAO ◽  
CHANGJIANG ZHU
Keyword(s):  
Cauchy Problem ◽  
Maximum Principle ◽  
Coupled System ◽  
Model System ◽  
Two Dimensions ◽  
Rarefaction Waves ◽  
Asymptotic Decay ◽  
The Maximum Principle ◽  
The Cauchy Problem ◽  
Asymptotic Decay Rate

In this paper, we consider the asymptotic decay rate towards the planar rarefaction waves to the Cauchy problem for a hyperbolic–elliptic coupled system called as a model system of the radiating gas in two dimensions. The analysis based on the standard L2-energy method, L1-estimate and the monotonicity of profile obtained by the maximum principle.

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