-
A Strategy for Solving the Non Symmetries Arising in Nonlinear Consolidation of Partially Saturated Soils
Héctor Ariel Di Rado,
Pablo Alejandro Beneyto,
Javier Luis Mroginski,
Juan Emilio Manzolillo
Issue:
Volume 3, Issue 2, April 2015
Pages:
31-35
Received:
7 January 2015
Accepted:
28 January 2015
Published:
2 February 2015
Abstract: The main scope of this paper is to present an alternative to tackle the problem of the non symmetries arising in the solution of the nonlinear couple consolidation problem based on a combination of different stress states. Being originally a non symmetric problem, it may be straightforward reduced to a symmetric one, and the conditions in which this reduction may be carried out, are addressed. Non linear saturation-suction and permeability-suction functions were regarded. The geometric model was developed considering an updated lagrangian description with a co-rotated Kirchhoff stress tensor. This description leads to a non-symmetric stiffness matrix and a simple alternative, using a symmetric constitutive matrix, is addressed to overcome this situation. The whole equation system was solved using an open finite element code FECCUND, developed by the authors. In order to validate the model, various examples, for which previous solutions are known, were solved. The use of either a strongly non linear and no symmetric formulation or a simple symmetric formulation with accurate prediction in deformation and pore-pressures is extremely dependent on the soil characteristic curves and on the shear efforts level, as well. A numerical example show the predictive capability of this geometrically non linear fully coupled model for attaining the proposed goal.
Abstract: The main scope of this paper is to present an alternative to tackle the problem of the non symmetries arising in the solution of the nonlinear couple consolidation problem based on a combination of different stress states. Being originally a non symmetric problem, it may be straightforward reduced to a symmetric one, and the conditions in which thi...
Show More
-
Mathematical Modelling of Endemic Malaria Transmission
Abadi Abay Gebremeskel,
Harald Elias Krogstad
Issue:
Volume 3, Issue 2, April 2015
Pages:
36-46
Received:
10 January 2015
Accepted:
6 February 2015
Published:
13 February 2015
Abstract: Malaria is an infectious disease caused by the Plasmodium parasite and transmitted between humans through bites of female Anopheles mosquitoes. A mathematical model describes the dynamics of malaria and human population compartments in terms of mathematical equations and these equations represent the relations between relevant properties of the compartments. The aim of the study is to understand the important parameters in the transmission and spread of endemic malaria disease, and try to find appropriate solutions and strategies for its prevention and control by applying mathematical modelling. The malaria model is developed based on basic mathematical modelling techniques leading to a system of ordinary differential equations (ODEs). Qualitative analysis of the model applies dimensional analysis, scaling, and perturbation techniques in addition to stability theory for ODE systems. We also derive the equilibrium points of the model and investigate their stability. Our results show that if the reproduction number, R0, is less than 1, the disease-free equilibrium point is stable, so that the disease dies out. If R0 is larger than 1, then the disease-free equilibrium is unstable. In that case, the endemic state has a unique equilibrium, re-invasion is always possible, and the disease persists within the human population. Numerical simulations have been carried out applying the numerical software Matlab. These simulations show the behavior of the populations in time and the stability of disease-free and endemic equilibrium points.
Abstract: Malaria is an infectious disease caused by the Plasmodium parasite and transmitted between humans through bites of female Anopheles mosquitoes. A mathematical model describes the dynamics of malaria and human population compartments in terms of mathematical equations and these equations represent the relations between relevant properties of the com...
Show More
-
On Quasi-Newton Method for Solving Unconstrained Optimization Problems
Felix Makanjuola Aderibigbe,
Kayode James Adebayo,
Adejoke O. Dele-Rotimi
Issue:
Volume 3, Issue 2, April 2015
Pages:
47-50
Received:
25 December 2014
Accepted:
14 February 2015
Published:
26 February 2015
Abstract: This paper discusses the use of quasi-Newton method algorithm employed in solving unconstrained optimization problems. The method is aimed at circumventing the computational rigours undergone using the Newton’s method.The Quasi –Newton method algorithm was tested on some benced mark problems with the results compared with the Conjugate Gradient Method. The results gotten using the Quasi-Newton Method compared favourably with results of existing CGM algorithm.
Abstract: This paper discusses the use of quasi-Newton method algorithm employed in solving unconstrained optimization problems. The method is aimed at circumventing the computational rigours undergone using the Newton’s method.The Quasi –Newton method algorithm was tested on some benced mark problems with the results compared with the Conjugate Gradient Met...
Show More
-
Natural Convection in Porous Triangular Enclosure with a Circular Obstacle in Presence of Heat Generation
Raju Chowdhury,
Md. Abdul Hakim Khan,
Md. Noor-A-Alam Siddiki
Issue:
Volume 3, Issue 2, April 2015
Pages:
51-58
Received:
22 February 2015
Accepted:
10 March 2015
Published:
21 March 2015
Abstract: The flow and heat transfer due to natural convection in a triangular enclosure filled with a fluid saturated porous medium with a circular body in presence of heat generation has been numerically analyzed. The bottom wall of the enclosure is heated at a constant temperature while the left and right inclined wall of the cavity is maintained at cold temperature. The cavity contains a circular body which is insulated. The governing equations are solved numerically subject to suitable boundary conditions by Galerkin’s weighted residuals scheme of finite element method. Results are presented by streamlines, isotherms, mean Nusselt numbers for the variant parameters such as heat generation (λ) and radius of the circular body (R). Prandtl number (Pr) and Rayleigh number (Ra) are considered unchanged. It is found that these parameters have significant effect on the flow and temperature fields inside the cavity.
Abstract: The flow and heat transfer due to natural convection in a triangular enclosure filled with a fluid saturated porous medium with a circular body in presence of heat generation has been numerically analyzed. The bottom wall of the enclosure is heated at a constant temperature while the left and right inclined wall of the cavity is maintained at cold ...
Show More
-
Maximizing Operations Processes of a Potential World Class University Using Mathematical Model
Agarana Michael,
Ayeni Foluso
Issue:
Volume 3, Issue 2, April 2015
Pages:
59-63
Received:
4 March 2015
Accepted:
17 March 2015
Published:
21 March 2015
Abstract: Many Universities are striving to attain the status of a World Class University. Some Parameters used in ranking universities include: Quality of education and teaching, Research, citation, international outlook, Alumni, Awards and Industry Outlook, operations and processes of a potential world class university should be directed optimally towards these parameters. This paper proposes a simple method of maximizing the operations processes of such universities in order to attain world class status. Operations Research techniques are employed to model the situation and solutions obtained using simplex method with the aid of computer software. It is observed that a lot of attention have to be paid to research publications, Alumni employment and international collaboration and linkages. Also the manpower should be motivated in order to become a world class university.
Abstract: Many Universities are striving to attain the status of a World Class University. Some Parameters used in ranking universities include: Quality of education and teaching, Research, citation, international outlook, Alumni, Awards and Industry Outlook, operations and processes of a potential world class university should be directed optimally towards ...
Show More
-
Analytical Study on Unsteady MHD Free Convection and Mass Transfer Flow Past a Vertical Porous Plate
S. F. Ahmmed,
M. K. Das,
L. E. Ali
Issue:
Volume 3, Issue 2, April 2015
Pages:
64-74
Received:
4 February 2015
Accepted:
24 February 2015
Published:
30 March 2015
Abstract: The unsteady MHD free convection and mass transfer boundary layer flow past a semi-infinite vertical porous plate immersed in a porous medium with heat source is studied. The plate moves with a uniform velocity in the direction of the fluid flow while the free stream velocity is considered to follow the exponentially increasing small perturbation law. The governing equations are solved analytical by using perturbation technique depending on the physical parameters including the Radiation parameter (R), the Magnetic parameter (M), the Prandtl number (Pr), the Grashof number for heat transfer (Gr), the Modified Grashof number for mass transfer (Gc), the Schmidt number (Sc), the soret number (S0), the permeability parameter (K) and the heat source (Q). The influence of these parameters on velocity field, temperature field, concentration field, skin friction, Nusselt number and Sherwood number at the plate are discussed with graphically.
Abstract: The unsteady MHD free convection and mass transfer boundary layer flow past a semi-infinite vertical porous plate immersed in a porous medium with heat source is studied. The plate moves with a uniform velocity in the direction of the fluid flow while the free stream velocity is considered to follow the exponentially increasing small perturbation l...
Show More
-
Clustering Problem with Fuzzy Data: Empirical Study for Financial Distress Firms
Issue:
Volume 3, Issue 2, April 2015
Pages:
75-80
Received:
15 February 2015
Accepted:
25 February 2015
Published:
2 April 2015
Abstract: In many real applications, the data of classification problems cannot be precisely measured. However, in an increasingly complex environment, these variables can be imprecise, qualitative or linguistic. In such a case, fuzzy set theory seems to be the convenient tool to fill this insufficiency. Thus, we proposed a new approach, based on the ranking function, which consists in solving the classification problems via fuzzy linear programming model. This approach has been applied for the financial distress firms. The obtained results are satisfactory in terms of correctly classified rates
Abstract: In many real applications, the data of classification problems cannot be precisely measured. However, in an increasingly complex environment, these variables can be imprecise, qualitative or linguistic. In such a case, fuzzy set theory seems to be the convenient tool to fill this insufficiency. Thus, we proposed a new approach, based on the ranking...
Show More
