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: 254

AJMCSR Articles

Visualization RCD (reinforced concrete design) table advisor for decision support activity

July 2010

Reinforced concrete design (RCD) activity requires the services of design table to pick bar sizes and area of specific bar groups. This allow reinforced concrete (RC) designers to use their intuition to pick the right bar size for detailing of RC Structures which virtually enhance reliable and satisfactory answers to RCD problems. With the advent of computer with its powerful memory, most RCD software available...

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

Norm properties of operators whose norms are Eigenvalues

July 2010

In this paper we present properties of a norm-attaining operator on a Hilbert space and there implications. We show that if T has norm attaining vector then    where   the  scalars  are  nonnegative  numbers.  Thus   T    satisfies a generalized Daugavet condition.   Key words: Numerical range, eigenvalue, normalloid...

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

Computing leaf rectangularity index: An estimation problem when the parameter is a norm of a vector

June 2010

A measure known as leaf rectangularity index (LRI) is estimated by means of bootstrap regression. The index, it is envisaged, will assist in discussing the geometry of leaf surfaces, if possible among different plants and across species. The study shows that one cannot obtain the point estimate of LRI before its interval estimate; rather, the interval estimate comes first before the point estimate. This paper gives the...

Author(s): Isaac Didi Essi

Subclasses of analytic functions associated with Wright generalized hypergeometric functions

June 2010

In this paper, we define a generalized class of starlike functions with negative coefficients and obtain coefficient estimates, distortion bounds, closure theorems and extreme points. Further we obtain modified Hadamard product, radii of close-to-convex, starlikeness and convexity for functions belonging to this class. Furthermore neighborhood results are discussed. Key words: Univalent functions, convex...

Author(s): G. Murugusundaramoorthy and N. Magesh

A novel analytical solution of steady flow over a rotating disk in porous medium with heat transfer by DTM-PADÉ

June 2010

In this study, the differential transform method (DTM) was applied to steady flow over a rotating disk in porous medium with heat transfer. The governing equations can be written as a system of nonlinear ordinary differential equations. The approximate solutions of these equations were obtained in the form of series with easily computable terms. Then, Padé approximant was applied to increase the convergence...

Author(s): Mohammad Mehdi Rashidi and Seied Amin Mohimanian Pour

A mathematical model of radioimmunotherapy for tumor treatment

June 2010

There is rapidly growing interest in the potential for synergistic, clinically relevant therapeutic responses by combining radiation therapy with immune response. A new mathematical model of radioimmunotherapy for tumor treatment was introduced. In this work, the linear and exponential spatial dependence of tumor parameters was used. The dose distributions model of radiotherapy with immune response for tumor treatment...

Author(s): Deepak Kumar and Sanjeev Kumar

Heat transfer over an unsteady porous stretching surface embedded in a porous medium with variable heat flux in the presence of heat source or sink

May 2010

The unsteady boundary layer flow over a porous stretching surface embedded in a porous medium in the presence of heat source or sink is studied. The unsteadiness in the flow and temperature fields is caused by the time dependence of the stretching velocity and the surface heat flux. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved...

Author(s): E. M. A. Elbashbeshy, D. M. Yassmin and A. A. Dalia

New generalizations of generalized geometric series distributions

May 2010

New generalizations of generalized geometric series distributions (NGOGGSD) and some of its subclasses are introduced. Recurrence relations and factorial moments are obtained. Several properties of NGOGGSD and its relations with other distributions are also discussed. Finally, a computer programmed in R-Software has been developed to ease the computations while estimating the parameters for data. Some sports sets of...

Author(s): Anwar Hassan

Some structural compatibilities of pre A*-algebra

April 2010

A pre A*-algebra is the algebraic form of the 3-valued logic. In this paper, we define a binary operation  on pre A*-algebra and show that  is a semilattice. We also prove some results on the partial ordering which is induced from the semilattice. We derive necessary and sufficient conditions for pre A*-algebra (A,Ù,Ú, (-)~) to become a Boolean algebra in terms of this partial...

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

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

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

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

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

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

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 0Ñ”W(A) or 0Ñ”W(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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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 

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

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

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

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

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

April 2009

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

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

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

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

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

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