Mathematical and Computational Applications

2058 KiB

Open AccessArticle

Line Shape and Profile of the LO Phonon Modes in Mixed Alloy System In1-x-yGaxAlyAs Epitaxial Layers Grown on InP

by M. M. Bülbül

Math. Comput. Appl. 1999, 4(1), 83-89; https://doi.org/10.3390/mca4010083 - 01 Apr 1999

Viewed by 1049

In this work. linewidth variations versus compositions of the first-order longitudinal optic (LO) phonon modes in the mixed alloy system are studied. The asymmetry and broadening of the LO modes is explained using a “spatial correlation” model with a Gaussian correlation function. The [...] Read more.

In this work. linewidth variations versus compositions of the first-order longitudinal optic (LO) phonon modes in the mixed alloy system are studied. The asymmetry and broadening of the LO modes is explained using a “spatial correlation” model with a Gaussian correlation function. The system investigated here were In_1-x-yGa_xAl_yAs quaternary alloys lattice-matched to InP(with x+y ≈47%). The quaternary alloy samples were grown as epilayers on (001) InP substrates by molecular beam epitaxy(MBE). Full article

2405 KiB

Open AccessArticle

Structural Forms and Energies of Nin, n=12-14, Clusters

by Ziya B. Güvenç, Dilek Güvenç and Julius Jellinek

Math. Comput. Appl. 1999, 4(1), 75-81; https://doi.org/10.3390/mca4010075 - 01 Apr 1999

Cited by 5 | Viewed by 1034

Abstract

Equilibrium structural forms of the Ni_n, n=12-14, clusters, as defined by an embedded-atom potential, are obtained using molecular dynamics and thermal quenching simulations. The isomers (locally stable geometric forms) are distinguished from those stationary structures that correspond to saddle points of [...] Read more.

Equilibrium structural forms of the Ni_n, n=12-14, clusters, as defined by an embedded-atom potential, are obtained using molecular dynamics and thermal quenching simulations. The isomers (locally stable geometric forms) are distinguished from those stationary structures that correspond to saddle points of the potential energy surface. Isomer statistics are obtained using a large number of initial quenching configurations generated along high-energy trajectories (the energies are high enough to “melt” the clusters). Probabilities of sampling the basins of attraction of the different isomers are computed and the spectra of their energies are analyzed. Full article

1536 KiB

Open AccessArticle

On the Theory of Generalized Ballistical Problem for Nonlinear Abstract Differential Equations

by A. Kh. Shamilov

Math. Comput. Appl. 1999, 4(1), 69-74; https://doi.org/10.3390/mca4010069 - 01 Apr 1999

Viewed by 1091

Abstract

In the present work, we have obtained principally new results for solvability and non-solvability of one problem for second order abstract differential equations with the main linear part. The method, based on solving corresponding Dirichlet problem, lies on the basis of present investigations. [...] Read more.

In the present work, we have obtained principally new results for solvability and non-solvability of one problem for second order abstract differential equations with the main linear part. The method, based on solving corresponding Dirichlet problem, lies on the basis of present investigations. In section 1, we present the formulation of the basic problem and reduce the short review of same investigations related to given problems. In section 2, we show the roll of the corresponding subsidiary boundary value problem for linear equation in the study of the basic problem. In section 3, we present the theorems of existence and nonexistence of the solution of the ballistical problem for nonlinear abstract differential equations with the linear part, in the case when the initial and the latter points of the desired solutions are not coinciding. Also we can prove the theorems of solvabilitv and non-solvability of considering problem in the case, when the Initial and the latter points desired trajectory are coinciding. Full article

2081 KiB

Open AccessArticle

D2 +Nin(T), n=7 and 9, Collision System

by Mustafa Böyükata, Perihan Durmuş, Süleyman Özçelik, Ziya B. Güvenç and Julius Jellinek

Math. Comput. Appl. 1999, 4(1), 61-67; https://doi.org/10.3390/mca4010061 - 01 Apr 1999

Viewed by 1098

Abstract

In this study the kinetics of reactions of Ni_n n=7 and 9, clusters with a deuterium D₂ molecule are studied via quasiclassical molecular dynamics. Dissociative chemisorption probabilities as functions of impact parameters, collision energies, and a rovibrational state of a molecule [...] Read more.

In this study the kinetics of reactions of Ni_n n=7 and 9, clusters with a deuterium D₂ molecule are studied via quasiclassical molecular dynamics. Dissociative chemisorption probabilities as functions of impact parameters, collision energies, and a rovibrational state of a molecule are calculated. And the corresponding reactive cross sections are evaluated. Resonance formation in the low collision energy region is discussed. Full article

2525 KiB

Open AccessArticle

Detection of the Starting of the Newly Applied Mass for Successive Weighing

by Mustafa Danacı and Adem Kalınlı

Math. Comput. Appl. 1999, 4(1), 53-59; https://doi.org/10.3390/mca4010053 - 01 Apr 1999

Cited by 1 | Viewed by 1139

Abstract

In this study, new approaches are proposed over a range of conditions with unknown loading time to determine the initial conditions and identify the explicit model parameters of successive weighing system in the early part of the transient response. When a new mass [...] Read more.

In this study, new approaches are proposed over a range of conditions with unknown loading time to determine the initial conditions and identify the explicit model parameters of successive weighing system in the early part of the transient response. When a new mass is applied to the platform, the starting of the newly applied mass is detected by modelling error approach and then predicted automatically using the Non-Linear Regression (NLR) method and the detection process is repeated for successive continuous weighing. Simulation results are provided to indicate the improvement in both speed and accuracy of the model and the mass prediction. Full article

2113 KiB

Open AccessArticle

A Dynamic Approach for Optimization of Open Pit Mine Invesments with Capital Budget

by Kaan Erarslan and Neş’e Çelebi

Math. Comput. Appl. 1999, 4(1), 45-51; https://doi.org/10.3390/mca4010045 - 01 Apr 1999

Viewed by 893

Abstract

Mining investments require huge capitals. Since mining has an economical aspect, a reasonable profit is expected at the end of investment. In other words, a mining investment is reasonable only if it brings a desirable income. In fact. The objective of mine investment [...] Read more.

Mining investments require huge capitals. Since mining has an economical aspect, a reasonable profit is expected at the end of investment. In other words, a mining investment is reasonable only if it brings a desirable income. In fact. The objective of mine investment should be the optimum profit, which means the maximum profit that can be handled under certain technical conditions and constraints. In this study, dynamic programming procedures have been investigated whether they can be applied on mining investments having budget constraint. A general and brief review of dynamic programming technique and the theoretical base of capital budget problem have been presented. Two examples have been employed for the applications; first is selecting optimal mine investment alternative(s) through a group of choices and second is selection of optimum excavation-machine alternative(s) providing maximum excavation capacity. By this way, applicability of dynamic programming has been examined on both the whole system and a sub-system. The objective function and recursion functions have been defined and applied on numerical cases. The results have revealed the validity of the approach for optimization of mining investments with budget constraint. Full article

1749 KiB

Open AccessArticle

The Singularities Near the Corner of a Viscoelastic Fluid in a 2D Cavity

by Demir Hüseyin, R. W. Willianms and F. T. Akyıldız

Math. Comput. Appl. 1999, 4(1), 39-44; https://doi.org/10.3390/mca4010039 - 01 Apr 1999

Cited by 4 | Viewed by 1275

Abstract

In this article finite differences are used to study viscoelastic incompressible flow of a Criminale Erickson Filbey fluid in a square cavity flow domain. In this case, the nature of corner singularities is examined in which the fluid is contained and the flow [...] Read more.

In this article finite differences are used to study viscoelastic incompressible flow of a Criminale Erickson Filbey fluid in a square cavity flow domain. In this case, the nature of corner singularities is examined in which the fluid is contained and the flow generated by the motion of one or more walls. The governing equations are formulated in terms of stream function and vorticity equation and the corresponding radial parts are defined by a fourth-order non-linear differential equations for Stokes flow. In recent years that mathematical formulations of viscoelastic flows often remain very complex velocity and stress field and then stress singularities are known to occur in several flows as in this article. Therefore, singularity behaviour became a very important current issue in fluid dynamics. However, this article is set up with the aim of examining the corner singularities for cavity driven flow in 2D for viscoelastic flow despite the Newtonian flow being well known. Then we show that the viscoelastic fluid has different singularity behaviour than the viscous fluid near the corner with respect to the shear-rate. Full article

1903 KiB

Open AccessArticle

Calculation of Temperature Distribution on a Crown Tooth by Using Three-Dimensional Finite Element Method

by H. Aykul, M. Toparlı and N. S. Köksal

Math. Comput. Appl. 1999, 4(1), 31-37; https://doi.org/10.3390/mca4010031 - 01 Apr 1999

Cited by 1 | Viewed by 1172

Abstract

The finite element was used to temperature changes with time to Au-AgPd alloy and porcelain crowns in three dimensional models of average maxillary second premolar. Temperature changes some critical nodes were calculated as a result of hot/cold liquid. Calculation programs were prepared by [...] Read more.

The finite element was used to temperature changes with time to Au-AgPd alloy and porcelain crowns in three dimensional models of average maxillary second premolar. Temperature changes some critical nodes were calculated as a result of hot/cold liquid. Calculation programs were prepared by authors using FORTRAN 77. The tooth was assumed isotropic, homogenous, elastic and unsymmetric. Full article

1788 KiB

Open AccessArticle

Reference Points in Magnetic Measurements

by Ömer Can Demirtaş and Rauf Mirzababayev

Math. Comput. Appl. 1999, 4(1), 25-30; https://doi.org/10.3390/mca4010025 - 01 Apr 1999

Viewed by 1104

Abstract

It is widely assumed that the magnetic phase transition temperatures have constant values. Application of the formalism of the high accuracy spectroscopic method shows that the Curie points used for the calibration processes in magnetic measurements are not uniquely defined, butt are related [...] Read more.

It is widely assumed that the magnetic phase transition temperatures have constant values. Application of the formalism of the high accuracy spectroscopic method shows that the Curie points used for the calibration processes in magnetic measurements are not uniquely defined, butt are related to the time scale of the measuring method. Full article

2446 KiB

Open AccessArticle

Procudere for Definition of Neighborhood in Faulty Hypercube Multiprocessor

by Novruz Allahverdi

Math. Comput. Appl. 1999, 4(1), 17-23; https://doi.org/10.3390/mca4010017 - 01 Apr 1999

Viewed by 915

Abstract

A procedure for definition of neighborhood and fault free subcubes in a faulty hypercube is developed in this study. The cube algebra operations are used for proposed procedure. With this, we can increase the number of faulty elements In the hypercube. Which is [...] Read more.

A procedure for definition of neighborhood and fault free subcubes in a faulty hypercube is developed in this study. The cube algebra operations are used for proposed procedure. With this, we can increase the number of faulty elements In the hypercube. Which is obstacle for effective data processing and communication processes in such a system. Full article

1941 KiB

Open AccessArticle

Mathematical Model of Sulphomethylation Process of Nonylphenol

by Novruz Bashirov

Math. Comput. Appl. 1999, 4(1), 9-15; https://doi.org/10.3390/mca4010009 - 01 Apr 1999

Viewed by 1217

Abstract

This paper concerns the development of the mat mathematical model of sulphomethylation process of nonylphenol based on planning of the experiment While developing the mathematical model of the process. a method of gross factor experiment (GFE). realizing all possible combinations of the factors [...] Read more.

This paper concerns the development of the mat mathematical model of sulphomethylation process of nonylphenol based on planning of the experiment While developing the mathematical model of the process. a method of gross factor experiment (GFE). realizing all possible combinations of the factors chosen. was used by us. By varying four factors on two (minimum and maximum) levels. the experimental values of yields of the product required (sodium sulphate of hydroxynonylbenzyl sulphonic acid). were obtained The coefficients of regression equations Bi are calculated by scalar products Then the adequacy of the mathematical model was checked Thus. a mathematical model of the sulphomethylation process l)f nonylphenol in the full scale of coordinates was obtained. Full article

2013 KiB

Open AccessArticle

Airflow over Wavy Yarn in Air-Jet Filling Insertion

by Sayavur Bakhtiyarov and Sabit Adanur

Math. Comput. Appl. 1999, 4(1), 1-7; https://doi.org/10.3390/mca4010001 - 01 Apr 1999

Cited by 1 | Viewed by 1004

Abstract

Airflow over the wavy yarn during air-jet filling insertion is analyzed theoretically Two flow regimes are considered in the analyses: subsonic and supersonic flows over the yarn. Expression for drag coefficient as a function of air velocity is obtained for both cases Numerical [...] Read more.

Airflow over the wavy yarn during air-jet filling insertion is analyzed theoretically Two flow regimes are considered in the analyses: subsonic and supersonic flows over the yarn. Expression for drag coefficient as a function of air velocity is obtained for both cases Numerical simulations were made for certain practical situations and comparison is made between the drag force on the yarn in subsonic and supersonic flows. Full article

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Math. Comput. Appl., Volume 4, Issue 1 (April 1999) – 12 articles , Pages 1-89

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