African Journal of
Mathematics and Computer Science Research

  • Abbreviation: Afr. J. Math. Comput. Sci. Res.
  • Language: English
  • ISSN: 2006-9731
  • DOI: 10.5897/AJMCSR
  • Start Year: 2008
  • Published Articles: 245

AJMCSR Articles

Estimation of T- period’s ahead extreme quantile autoregression function

April 2010

This paper considers the estimation of extreme quantile autoregression function by using a parametric model. We combine direct estimation of quantiles in the middle region with that of extreme parts using the model and results from extreme value theory (EVT). The volatility used to scale the residuals is estimated indirectly, without estimating conditional mean, using the conditional quantile (CQ) range. The estimators...

Author(s): Peter Nyamuhanga Mwita

  • Article Number: 73AABDC8862

Measuring the stress, strain and strain-rate in heat treated medium carbon steel samples and finding the constituted material related properties

March 2010

Mechanical failure of component parts as well as in build up structures can be prevented if proper quality control is carried out at point of component’s manufacture. Engineers are known to analyze samples from which accurate predictions are made about the properties of the materials that are produced for the purpose of component and structural processing. This work had produced and tested heat treated 1030 steel...

Author(s): A. G. F. Alabi, T. K. Ajiboye and H. D. Olusegun

  • Article Number: 8B6FF8D8812

Principal component procedure in factor analysis and robustness

March 2010

Principal component procedure has been widely used in factor analysis as a data reduction procedure. The estimation of the covariance and correlation matrix in factor analysis using principal component procedure is strongly influenced by outliers. This study investigates the robustness of principal component procedure in factor analysis by generating random variables from five different distributions which are used to...

Author(s): Joy Chioma Nwabueze

  • Article Number: CC194D88841

Conflict resolution using statistical approach

February 2010

Conflict can be described as a condition in which actions of one person prevent or compel some outcome at the resistance of the other. Quite often this can be seen as “two or more competing, often incompatible, responses to same event”. In this paper, a statistical approach to conflict resolution using the concept of bargaining game theory is presented. The approach gives chances of failure that are minimal...

Author(s): O. Vincent Omwenga and N. Peter Mwita

  • Article Number: C89F5F18776

Relationship between continuity and momentum equation in two dimensional flow

February 2010

In this paper a quantitative discussion on a theory describing the relationship between the continuity and momentum equation in two dimensional flow together with the momentum equation in vectorial form:  is reported. Via expanding in cylindrical polar coordinates, the end result is proved to be Euler equation.   Key word: Continuity equation, momentum equation, cylindrical coordinates,...

Author(s): I. A. Idowu and J. B. Adewuyi

  • Article Number: A6141528786

Invariance of numerical range under isometric transformation

February 2010

In this paper, we look at some properties of isometries and conditions for a quasi-affinity to be unitary. Among other results it is proved that if A is a partial isometry such that either 0єW(A) or 0єW(An) for some positive integer n then A is unitary.   Key words: Numerical range and unitary operator.

Author(s): A. W. Wafula and J. M. Khalagai

  • Article Number: F3D562E8793

A robust method of estimating covariance matrix in multivariate data analysis

January 2010

We proposed a robust method of estimating covariance matrix in multivariate data set. The goal is to compare the proposed method with the most widely used robust methods (Minimum Volume Ellipsoid and Minimum Covariance Determinant) and the classical method (MLE) in detection of outliers at different levels and magnitude of outliers. The proposed robust method competes favourably well with both MVE and MCD and performed...

Author(s): G. M. Oyeyemi and R. A. Ipinyomi

  • Article Number: 0D675978744

The efficiency of the linear classification rule in multi-group discriminant analysis

January 2010

A Monte Carlo study was performed to assess the relative efficiency of the linear classification rule in 2, 3 and 5-group discriminant analysis. The simulation design took into account the number  of variables (4, 6, 10, and 18), the size sample  so that: = 1.5, 2.5 and 5. Three values of the overlap, e of the populations were considered (0.05; 0.1; 0.15) and their common distribution was...

Author(s): Romain Lucas Glèlè Kakaï, Dieter Pelz and Rudy Palm

  • Article Number: 9A858868756

Reliability and economic analysis of 2-out-of-3 redundant system with priority to repair

December 2009

  Two reliability models have been developed to compare some reliability and economic measures for a 2-out-of-3 redundant system having two original units (called standard units) and one duplicate unit which areinitially taken as spare in cold standby. The system is considered in up-state if any two of original and/or duplicate units are operative in parallel mode. The original unit is inspected at its...

Author(s):   S. Chander and R. K. Bhardwaj

  • Article Number: A3DA4D64703

Curve concentration for a singularly perturbed Neumann problem in three dimensional domain

December 2009

In this paper we consider the following problem  where  is a bounded domain in  with smooth boundary,  is a small parameter,  denotes the outward normal of  and . Let  be a straight line intersecting with  at exactly two points. We will prove the existence of a solution  possessing curve concentrating set near , exponentially small in  at any positive distance from the...

Author(s):   Jun Yang

  • Article Number: 283F7534742

Visualizing the behaviour of reinforced concrete beam structure under various types of loadings

November 2009

  This paper describes an approach to visualizing the detection of failure in Reinforced Concrete Beam Structure under various types of loadings. Several Reinforced Concrete Design (RCD) tools have been developed to support RCD, but there is little evidence that these solutions address the needs of the users. We studied RCD analysts’ daily activities in order to understand their routine work practices and...

Author(s):   L. O. Yusuf, O. Folorunso, A. T. Akinwale and A. I. Adejumobi

  • Article Number: EFC065A4669

Relative efficiency of non parametric error rate estimators in multi-group linear discriminant analysis

November 2009

  A Monte Carlo study was achieved to assess the relative efficiency of ten non parametric error rate estimators in 2, 3 and 5-group linear discriminant analysis. The simulation design took into account the number ρ of variables (4, 6, 10, 18) together wit the size sample n so that: n/ρ = 1.5, 2.5 and 5. Three values of the overlap, e of the populations were...

Author(s):   Romain Lucas Glèlè Kakaï, Dieter Pelz and Rudy Palm

  • Article Number: B8EC8FE4672

A catastrophic-cum-restorative queuing model with correlated input for the cell traffic generated by new broadband services

November 2009

  A Catastrophic-cum-Restorative Queuing Model has been developed for the cell traffic generated by New Broadband services. Transient analysis of the queuing model has been carried out. Some particular cases of the model have been derived and discussed.   Key words:  Catastrophes, correlation, broadband services, restoration.

Author(s):   Rakesh Kumar

  • Article Number: 24E49D84678

Comparison of electron-plasmon scattering effect on low-field electron mobility in ZnO and SiC

October 2009

  Iterative technique is used to solve Boltzmann transport equation for calculating temperature and doping dependencies of electron mobility in ZnO and SiC materials. The two-mode nature of the polar optic phonons is considered jointly with deformation potential acoustic, piezoelectric, ionized impurity and electron-plasmon scattering. Band non-parabolicity, admixture of p functions, arbitrary...

Author(s):   H. Arabshahi and M. Rezaee Rokn-Abadi

  • Article Number: 9511BAC4609

Cluster analysis of improved cassava varieties cultivated at Onne, Nigeria by the international institute of tropical agriculture

October 2009

  Secondary data on proximate composition of “fufu” flour taken from forty three cassava mosaic disease (CMD) resistant varieties were used for this work. Agglomerative hierarchical cluster analysis was performed on the squared Euclidean distance matrix. The distance coefficients generated between the forty three CMD resistant varieties ranged from 0.000 to 89.120. Six (6) distinct groups were...

Author(s):   Nwabueze, Joy Chioma

  • Article Number: D69BD914640

Enhanced data mining analysis in higher educational system using rough set theory

October 2009

  One of the biggest challenges that higher education faces today is predicting the behavior of students. Institutions would like to know, something about the performances of the students group wise. Behrouz–Minaei-Bidgoli (2004) investigated a web based educational system using data mining techniques. He proposed a problem to investigate the performances of the students when the large data base of...

Author(s): P. Ramasubramanian, K. Iyakutti and P. Thangavelu

  • Article Number: 97AE1094581

A dimension result for polar sets of Brownian path in n-spaces

September 2009

Let T(x,r) denote the occupation measure of the ball of radius r centered at x for Brownian motion {Xr},0 < t < 1 in Rn , n > 3. We consider the set and show that for a = 0,h(r) = r2 (logr)λ, λ > 1. Moreover, E0 n Ea = ø for a > 0. We deduce that the Hausdorff dimension of  E0 is 2 for n > 3   Key words: Brownian motion, Hausdorff dimension,...

Author(s):   A. C. Okoroafor and P. U. Uzoma

  • Article Number: A5E3EF14475

Causal relationship between gross domestic product and personal consumption expenditure of Nigeria

September 2009

  This study employed regression analysis to investigate the casual relationship between gross domestic product and personal consumption expenditure of Nigeria using data from 1994 - 2007. A non insignificant value of 0.0514 was obtained as a slope coefficient indicating that an increase in gross domestic product has no significant effect on the personal consumption expenditure of Nigeria. This was further...

Author(s): Nwabueze Joy Chioma

  • Article Number: DF0B5E14513

Adaptation of the preemptive handoff scheme in an integrated mobile communication environment

September 2009

  A new preemptive handoff scheme in integrated mobile communication environment is presented in this paper. The preemptive handoff schemes have worked in such a way that data types of lesser priority have been preemptive in an ad-hoc fashion. In the proposed scheme, the cell is divided into two regions, the usable area and the handoff region. The right of preemption has been given to incoming handoff real-time...

Author(s):   Chiranjeev Kumar and Rajeev Tripathi

  • Article Number: 8FB1C0B4543

Applications of soft computing techniques in materials engineering: A review

August 2009

  Within the last two decades, a substantial amount of research efforts has been directed at the application of Soft Computing (SC) techniques in engineering. This paper provides a systematic review of the literature emanating from these efforts with particular focus on materials engineering. The primary aim is to provide background information, motivation for applications and an exposition to the methodologies...

Author(s):   Odetunji A.  Odejobi and Lasisi E. Umoru

  • Article Number: 01B5CE54389

On sandwich theorems of analytic functions involving Noor integral operator

August 2009

  In this paper, we introduce sufficient conditions for subordination and superordination for subclass of analytic functions containing Noor integral operator. On the other hand, we prove the subordination and superordination results by some theorem studies and proofs. There are also obtained a sandwich results by different ways.   Key words: Noor integral...

Author(s):   R. W. Ibrahim and M. Darus

  • Article Number: 200843C4396

M|G|∞ queue system parameters for a particular collection of service time distributions

August 2009

  The problems that arise in the computation of the moments of a particular collection of service time distributions, for which the M|G|∞ busy period and busy cycle become very easy to study, are presented in this paper. It is shown how to overcome them. The busy cycle renewal function, the “peak” and the “modified peak” for the M|G|∞ busy period and busy cycle in the case of...

Author(s):   Ferreira, Manuel Alberto M. and Andrade, M.

  • Article Number: 24437824406

Slip formulation for numerical simulations of jumping paratroopers

August 2009

  The aim is to develop computational techniques for studying aerodynamic interactions between multiple objects when an object exits and separates from an aircraft. The object could be a paratrooper jumping out of a transport aircraft or a package of emergency aid dropped from a cargo plane. In all these cases, the computational challenge is to predict the dynamic behavior and path of the object, so that the...

Author(s):   Victor Udoewa

  • Article Number: E7BFE5B4417

Modeling laminar flow between a fixed impermeable disk and a porous rotating disk

August 2009

  We formulate a mathematical model that governs operations of many engineering systems particularly the ceiling fan to explain the fluid flow between the fixed impermeable and the porous rotating disks. The model is based on the continuity and the Navier-Stokes equations which are reduced into a set of coupled ordinary differential equations through transformation by similarity variables. The coupled ordinary...

Author(s):   D. P. Kavenuke, E. Massawe and O. D. Makinde

  • Article Number: BDD7B234422

Graphics to fuzzy elements in appraisal of an in-house software based on inter-failure data analysis

July 2009

  The performance of any software can be measured, approximately, by three parameters; Reliability, Availability and Maintainability. They provide information about the robustness of the software under consideration. In this work, a software is developed to computerize University of Ilorin student’s results and is designated as an IN-HOUSE Software. The formalism of fuzzy logic is used to investigate its...

Author(s):   J. O. Omolehin, K. Rauf, R. G. Jimoh and O. C. Abikoye

  • Article Number: 1955D3F4357

Stability analysis of stochastic model of stock market price

July 2009

  A stability analysis of stochastic model of price change at the floor of a stock market is considered. Precise conditions are obtained which determine the equilibrium price and growth rate of the stock shares in a particular case. In general, stability in a numerical procedure for the Black-Schole’s partial differential equation is established. An illustrative example is provided.   Key...

Author(s):   B. O. Osu, A. C.Okoroafor and C .Olunkwa

  • Article Number: 8A424474364

Robustness of the maximum likelihood estimation procedure in factor analysis

June 2009

  Random variables generated from five distributions were used to represent the common and specific factors in factor analysis in order to determine the robustness of the maximum likelihood estimation procedure. Five response variables were chosen for this study each with two factors. The chosen variables were transformed into linear combinations of an underlying set of hypothesized or unobserved components...

Author(s):   Nwabueze, Joy Chioma, Onyeagu, Sidney I. and Ikpegbu Onyedikachi

  • Article Number: FBF425F4318

Statistical analysis of dependence structure of improved cassava varieties in Nigeria

June 2009

  Multivariate methods were used to analyze a set of data on the proximate compositions of fufuflours processed from 43 different cassava mosaic disease (CMD) resistant varieties from National Root Crop Research Institute (NRCRT) Umudike Nigeria. The factor analysis reveals that three factors accounted for 77.8% of the total variables in the data. Factor 1 has eigenvalue of 3.082, factor 2 has an eigen...

Author(s):   Nwabueze Joy Chioma

  • Article Number: CBC5A274338

A collocation multistep method for integrating ordinary differential equations on manifolds

May 2009

  This paper concerns a family of generalized collocation multistep methods that evolves the numerical solution of ordinary differential equations on configuration spaces formulated as homogeneous manifolds. Collocating the general linear method at x = xx+k for k = 0,1,….s, , we obtain the discrete scheme which can be adapted to homogeneous spaces. Varying the values...

Author(s):   J. O. Fatokun and I. K. O. Ajibola

  • Article Number: AFC01693706

When does the pooled variance t-test fail?

May 2009

  The pooled variance t-tests used prominently for comparing means between two groups is usually restricted with the assumptions of normality and homogeneity of variances. However, the violation of the assumptions happens in many real world data. In this study, the conditions where the pooled variance t-test would fail were investigated. The performance of the t-test was evaluated under different...

Author(s):   Teh Sin Yin and Abdul Rahman Othman

  • Article Number: 0CC63383714

Application of variational iteration method to coupled system of nonlinear partial differential physical equations

May 2009

  In this article 2 examples of the coupled system of nonlinear partial differential physical equations including diffusion-reaction equation have been investigated by means of variational iteration method which is a new numerical method for solving these types of equations. The results are presented finally in comparison with the exact solution, which show a good agreement and consistency with the exact...

Author(s):   Abdoul R. Ghotbi, A. Barari, M. Omidvar and D. D. Ganji

  • Article Number: A57C6493723

A class of collocation methods for general second order ordinary differential equations

May 2009

  In this paper, self starting hybrid block method of order (4,3,3)T is proposed for the solution of general second order initial value problem of the form Y” = f (x, y, y’) directly without reducing it to first systems of odes. The continuous formation of the integrator enable us to differentiate and evaluate at some grids and off-grid points to take care of...

Author(s):   Y. A. Yahaya and A. M. Badmus 

  • Article Number: 4C82B454303

Pre A*-Algebra as a Poset

May 2009

  This paper is a study on algebraic structure of pre A*- algebra. We define center of a pre A*-algebra, B(A) = {x Î A/ x Ú x0/0 1} and prove that B(A) is a Boolean algebra. We define ordering relation  on pre A*- algebra A by x ≤ y if yÙx = xÙy = x and prove that ≤ is a partial ordering on A and also find necessary conditions...

Author(s):   J. Venkateswara Rao and K. Srinivasa Rao

  • Article Number: 18A03F44309

Profile of conjugate gradient method algorithm on the performance appraisal for a fuzzy system

April 2009

  The formalism of Minkwosky’s inequality in Omolehin (2007a) is used in this work fundamentally to generate the fuzzy model for system performance appraisal in two public examinations in Nigeria. The Conjugate Gradient Method Algorithm (CGM) is employed to evaluate the validity of our results from the large system fuzzy performance. Results showed that our methods are credible and...

Author(s):   J. O. Omolehin, A. O. Enikuomehin, R. G. Jimoh and K. Rauf

  • Article Number: 130A5DB3567

Development of a mathematical model for error propagation in engineering calculations involving many variables function

April 2009

  In this research, a mathematical model for error propagations in many variables functions had been developed. The development employs both Taylor theorem and binomial coefficient of expansion. Verification of the models were done through computer simulation by comparing the results of the model with the actual difference between the result given by the function in question, when computed...

Author(s):   S. K. Fasogbon

  • Article Number: 7808B783583

Some affine connexions in a generalized structure manifold

April 2009

  In this paper we have studied some affine connexions in a generalised structure manifold. Certain theorems are have also been proved, which are of great geometrical importance.   Key words: C∞-manifold, generalised structure, generalised metric structure, F- structure, π structure, AMS Subject Classification Number: 53

Author(s):   R. P. Singh and S. D. Singh

  • Article Number: C604F973610

A simple experimental verification for Einstein’s variance of mass with velocity equation

April 2009

Author(s):   M. Sivasubramanian and S. Kalimuthu

  • Article Number: 7475EB43678

Mathematical model of ecological disturbances in the oil rich Niger Delta region of Nigeria

March 2009

  An important class of interactions between biological species is the stability. We investigate the ecological, biological and economical impacts of petroleum exploration on the Niger Delta region of Southern Nigeria. A modified reaction-diffusion model describing the spread of the predators into the prey populations is adopted to establish the interaction between the parties involved. An attempt was made to...

Author(s):   O. O. Ugbebor and P .O. K. Aiyelo

  • Article Number: 4AE95703536

On two-sample test for detecting differences in the IFR property of life distributions

March 2009

  A test proposed for testing whether one distribution is more Increasing Failure Rate (IFR) than another, based on a measure of IFR is presented in this paper. The asymptotic normality of the proposed test statistic was also established. The asymptotic null variance from the data was estimated since the variance depends on the unknown distribution. The Pitman asymptotic efficacies of the proposed test...

Author(s):   Parameshwar V. Pandit and Nagaraj V. Gudaganavar

  • Article Number: F8015A13550

An empirical optimal portfolio selection model

February 2009

  We consider risk arising from changes in the prices of financial assets. We propose a risk measure based on asymptotic power law behaviour for optimal portfolio selection in a single period. We apply this measure to compute explicitly the optimal portfolio when the underlying security prices follow a Weibull distribution. An illustrative example is given.   Key words: Asymptotic power law,...

Author(s):   A. C. Okoroafor and B. O. Osu

  • Article Number: CA194F13518

Reliability equivalence factors for some systems with mixture weibull failure rates

February 2009

  In this article, the failure rates of the system's components are functions of time t. We study two cases (i) the mixture of two stages of life time distribution with weibull failure rates, (ii) the mixture of two stages failure rates with weibull distribution. The reliability equivalence factors of some systems with identical components are obtained. Two different methods are used to improve the...

Author(s):   A. Mustafa

  • Article Number: BDEF0BD3524

Multi agent system for resource allocation and monitoring

October 2008

  The objective of this paper is to present a model that uses Multi Agent Technology to assist Fund Allocating Agencies (FAA) to allocate limited funds to most deserving among competing organizations called Fund Seekers (FS) and monitoring the utilization of allocated funds. These funds are given to execute their projects in Research and Development or to impart quality education. In India, the beneficiaries of...

Author(s):   M. Syamala Devi and Manish Arora

  • Article Number: 25DE4EE3487

Conjugate gradient method for non-positive definite matrix operator

October 2008

  The conjugate Gradient Method relies on symmetric positive definite property of a matrix operator. In this work, we investigate and establish the case of non-positive symmetric matrix operator using various forms of conversions and transformations on the operator.   Key words: Hilbert Space, Positive Symmetric Matrix, Quadratic Functional, Conjugate, Gradient Method.

Author(s):   Omolehin J.O., Abdulrahman M.K.A., Rauf K.and Udoh P.J. 

  • Article Number: 0AF15253495

Thermal modeling and performance evaluation of arch shape greenhouse for nursery raising

August 2008

  This paper presents mathematical model for predicting thermal environment inside the arch shape greenhouse. Predicted thermal environment inside the greenhouse helped to select the crop nursery for growing inside the greenhouse. Actual thermal environment inside the greenhouse compared with predicted thermal environment. Experimental and predicted values of greenhouse temperature were almost same with...

Author(s):   S. H. Sengar and S. Kothari  

  • Article Number: 6BD9FD83445

Dual factor routing protocol for mobile ad hoc networks

August 2008

  Mobile ad hoc networking works properly only if the participating nodes cooperate in routing and forwarding. In this work, the question of how to enable a system to operate despite the presence of misbehavior node is considered. Node misbehavior due to selfish or malicious reasons or faulty nodes can significantly degrade the performance of mobile ad hoc networks. A new protocol called DUAL Factor is proposed...

Author(s):   R. Praveen Sam, P. Chandrasekhar Reddy and B. Stephen Charles

  • Article Number: A6B05A93475

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