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On Optimization of a Coxian Queueing Model with Two Phases
Vedat Sağlam,
Merve Uğurlu,
Erdinç Yücesoy,
Müjgan Zobu,
Murat Sağır
Issue:
Volume 3, Issue 2, April 2014
Pages:
43-47
Received:
30 January 2014
Published:
20 March 2014
DOI:
10.11648/j.acm.20140302.11
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Abstract: In this study we have obtained stochastic equation systems of a Coxian queueing model with two phases where arrival stream of this model is according to the exponential distribution with λ parameter. The service time of any customer at server i (i=1,2) is exponential with parameter μ_i. In addition we have obtained state probabilities of this queueing model at any given t moment.Furthermore performance measures of this queueing system are calculated. Various queueing systems are found for some values of α probability and service parameters: if α=1and µ_1=µ_2taken then M/E_2/1/ 0 queueing model is obtained, for α=1it is shown that service time of a customer is according to hypoexponential, if α=0 is taken we have M/ M/1/ 0 queueing system. Lately,an application of this queueing model is done. The optimal value of the mean customer number in the system is found. Finally, optimal ordering according to the loss probability is obtained by changing the service parameters .A numerical example is given on the subject
Abstract: In this study we have obtained stochastic equation systems of a Coxian queueing model with two phases where arrival stream of this model is according to the exponential distribution with λ parameter. The service time of any customer at server i (i=1,2) is exponential with parameter μ_i. In addition we have obtained state probabilities of this que...
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Effect of Variable Thermal Conductivity on Heat and Mass Transfer Flow over a Vertical Channel with Magnetic Field Intensity
Ime Jimmy Uwanta,
Halima Usman
Issue:
Volume 3, Issue 2, April 2014
Pages:
48-56
Received:
30 March 2014
Accepted:
22 April 2014
Published:
30 April 2014
DOI:
10.11648/j.acm.20140302.12
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Abstract: The objective of this paper is to study thermal conductivity and magnetic field intensity effects on heat and mass transfer flow over a vertical channel both numerically and analytically. The non-linear partial differential equations governing the flow are non-dimensionalised, simplified and solved using Crank Nicolson type of implicit finite difference method. To check the accuracy of the numerical solution, steady state solutions for velocity, temperature and concentration fields are obtained by using perturbation method. Graphical results for velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number have been obtained, to show the effects of different parameters entering in the problem. Results from these study shows that velocity, temperature and concentration increases with the increase in the dimensionless time until they reach steady state value. Also, it was observed that the analytical and numerical solutions agree very well at large values of time.
Abstract: The objective of this paper is to study thermal conductivity and magnetic field intensity effects on heat and mass transfer flow over a vertical channel both numerically and analytically. The non-linear partial differential equations governing the flow are non-dimensionalised, simplified and solved using Crank Nicolson type of implicit finite diffe...
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Zeros and Asymptotic Limits of Löwdin Orthogonal Polynomials with a Unified View
Ramesh Naidu Annavarapu,
Vipin Srivastava
Issue:
Volume 3, Issue 2, April 2014
Pages:
57-62
Received:
27 March 2014
Accepted:
24 April 2014
Published:
10 May 2014
DOI:
10.11648/j.acm.20140302.13
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Abstract: The zeros and asymptotic limits of two new classes of orthogonal polynomials, which are derived by applying two orthogonalization procedures due to Löwdin to a set of monomials, are calculated. It is established that they possess all the properties ofthe zeros of a polynomial. Their asymptotic limits are found. A Unified view of all the Löwdin orthogonal polynomials together with the standard classical orthogonal polynomials are presented in a unique graph.
Abstract: The zeros and asymptotic limits of two new classes of orthogonal polynomials, which are derived by applying two orthogonalization procedures due to Löwdin to a set of monomials, are calculated. It is established that they possess all the properties ofthe zeros of a polynomial. Their asymptotic limits are found. A Unified view of all the Löwdin orth...
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Method for Integrating Tabular Functions that Considers Errors
Vladimir V. Ternovski,
Mikhail M. Khapaev
Issue:
Volume 3, Issue 2, April 2014
Pages:
63-67
Received:
3 May 2014
Accepted:
13 May 2014
Published:
20 May 2014
DOI:
10.11648/j.acm.20140302.14
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Abstract: If experimental tables are numerically integrated using quadrature formulas, then the measurement errors of the physical instrument is not taken into account. The result of such numerical integration will be inaccurate because of the accumulation of errors due to the summation of random values, and the residual term of the quadrature formula cannot be calculated using solely classical concepts. The traditional approach consists of applying various smoothing algorithms. In this case, methods are used that are unrelated to the problem of integrating itself, which leads to excessive smoothing of the result. The authors propose a method for numerical integration of inaccurate numerical functions that minimizes the residual term of the quadrature formula for the set of unknown values based on the error confidence intervals by using ill-posed problem algorithms. The high level of effectiveness of this new method, for which it is sufficient to know the error level of the signal, is demonstrated through examples.
Abstract: If experimental tables are numerically integrated using quadrature formulas, then the measurement errors of the physical instrument is not taken into account. The result of such numerical integration will be inaccurate because of the accumulation of errors due to the summation of random values, and the residual term of the quadrature formula cannot...
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