### African Journal ofMathematics 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

An inventory model for deteriorating items with different constant demand rates

July 2012

In this paper, we study the inventory model for deteriorating items with different constant demand rates, that is, the demand rate is piecewise linear function. The deterioration rate is assumed as constant. We have proposed an inventory replenishment policy for this type of inventory model. The numerical solution of the model is also obtained and examined.   Key words: Inventory,...

Modeling of a predator prey dynamic system with harvesting using the lattice gas approach

May 2012

This paper uses the lattice gas model to incorporate spatial and stochastic elements in a prey-predator dynamic system. In this system, the habitat is partitioned in two adjacent patches, one of them being a prey reserve. The habitat is populated by two competing prey and a common predator. In the reserve, prey harvesting is prohibited. In the other patch, harvesting of one of the prey is allowed at a...

Statistical modeling of wastage using the beta distribution

May 2012

This work attempts to fit a set of observed industrial wastage to the beta distribution using the Chi-square goodness of fit test and it was found to fit the beta distribution at 1% significance level. The mean and the variance of the wastage proportion were found to be 0.429 and 0.0395, respectively. The parameters of the beta distribution were α = 2.25 and β = 2.97. The skewness of the beta...

The maximal allocated cost and minimal allocated benefit for interval data

April 2012

This Paper deals with calculating the minimal and maximal shares of individuals or organizations based on different criteria. Suppose that players are selfish and the score for each criterion for a player is an interval. Each player makes any possible efforts to bring about his or her ideal condition. In this paper a new scheme to calculate the minimal allocated cost and the maximal allocated benefit for...

Asymptotic behavior of solutions of nonlinear delay differential equations with impulse

April 2012

This paper studies the asymptotic behavior of solutions of the second-order nonlinear delay differential equations with impulses:     and some sufficient conditions are obtained.   Key words: Asymptotic behavior, second-order nonlinear delay differential equation, impulses.

Logistic preference function for preference ranking organization method for enrichment evaluation (PROMETHEE) decision analysis

March 2012

Decision problems relate to problems of ranking, choice and detection with regards to whether a decision alternative efficient parameter satisfies some given conditions. The preference ranking organization method for enrichment evaluation (PROMETHEE) methods of decision analysis are recognized as being efficient in solving problems involving ranking.  Various preference functions have been established in...

Mathematics as a sort of technology

March 2012

Mathematics has double characters including science and technology. The direct research object of mathematics is mode which is the carrier of information, and the evolvement of mode is the process of information processing and information conversion. This paper has described the three characters of mathematic: operation, instrument and invention, which shows mathematic is a sort of technology. In addition to some expels...

Temperature-dependent thermal stress determination of an isotropic circular annular fin

March 2012

This paper is concerned with an inverse thermoelastic problem in which we need to determine the temperature distribution, unknown temperature gradient, displacement, stress functions and thermal stresses on the outer curved surface of a thin annular fin when the interior heat flux is known. Finite classical Marchi-Zgrablich transform and Laplace transform techniques have been utilized to obtain the solution for the...

Improving the order selection of moving average time series model

March 2012

We propose an approach could be used to select the right order of moving average model. We used simulation study to compare four model selection criteria with and without the help of our approach. The comparison of the four model selection criteria was in terms of their percentage of number of times that they identify the right order of moving average model with and without the help of our approach. The simulation...

Investigation on the effect of stent in unsteady blood flow

February 2012

In this work, we tried to determine the fact that an interest in optimal stents shapes helps to minimize fluid swirl and to maximize shear stress on the wall artery in order to reduce the risk of the restenosis in stented segments. Our study deals with three geometric parameters of the stent, namely the strut spacing, the strut height and the strut width. These parameters have direct effect on blood...

Thermal deflection of a thin circular plate with radiation

February 2012

This paper deals with the determination of thermal deflection of a thin circular plate defined as ;. A circular plate is considered having arbitrary initial temperature and subjected to radiation type boundary condition which is fixed at . The non homogeneous type boundary conditions are maintained at plane surfaces of the plate. The governing heat conduction equation has been solved by using...

Application of Bousinesqâ€™s and Westergaardâ€™s formulae in analysing foundation stress distribution for a failed telecommunication mast

February 2012

The concurrent foundation failure of telecommunication masts in Nigeria and all over the world which endanger the lives and properties of residents situated within the fall distance of the telecommunication mast is a thing of great concern. In this study, a GSM mast that underwent foundation failure at Ibadan, Oyo State, Nigeria was critically examined with a view to providing engineering solution. The soil...

Utilization of mixture of andin imputation for missing data in post-stratification

February 2012

To estimate the population mean using auxiliary variable there are many estimators available in literature like-ratio, product, regression, dual-to-ratio estimator and so on. Suppose that all the information of the main variable is present in the sample but only a part of data of the auxiliary variable is available. Then, in this case none of the aforementioned estimators could be used. This paper presents an...

Critical thinking: Essence for teaching mathematics and mathematics problem solving skills

February 2012

Critical thinking is a learned skill that requires instruction and practice. Mathematics education instructors at both the secondary and post-secondary levels can enhance students’ critical thinking skills by (i) using instructional strategies that actively engage students in the learning process rather than relying on lecture and note memorization, (ii) focusing instruction on the process of learning...

Einstein's equivalence principle has three further implications besides affecting time: T-L-M-Ch theorem (â€œTelemachâ€)

February 2012

General relativity is notoriously difficult to interpret. A "return to the mothers" is proposed to better understand the gothic-R theorem of the Schwarzschild metric of general relativity. It is shown that the new finding is already implicit in Einstein's equivalence principle of 1907 and hence in special relativity (with acceleration included). The TeLeMaCh theorem, named onomatopoetically...

Cross efficiency by using common weights for fuzzy data

February 2012

This paper firstly revists the cross efficiency evaluation method which is an extention tool of data envelopment analysis (DEA), then analyzes the potential flawes which happens when the ultimate average cross efficiency scores are used. In this paper, we consider the decision making units (DMUs) as the players in a cooperative fuzzy game, where the characteristic function values of coalitions are...

Flow induced by non-coaxial rotations of porous disk and a fluid in a porous medium

January 2012

This paper deals with the flow of an incompressible, viscous and electrically conducting fluid in a porous medium when no slip condition is no longer valid. The fluid is bounded by a non-conducting porous disk. The flow is due to non-coaxial rotations of porous disk and a fluid at infinity. The fluid is electrically conducting in the presence of a constant applied magnetic field in the transverse direction....

A study on a novel method of mining fuzzy association using fuzzy correlation analysis

January 2012

Two different data variables may behave very similarly. Correlation is the problem of determining how much alike the two variables actually are and association rules are used just to show the relationships between data items. Mining fuzzy association rules is the job of finding the fuzzy item-sets which frequently occur together in large fuzzy data set, where the presence of one fuzzy item-set in a record...

A sampling plan with producerâ€™s allowable risk (PAR) at maximum allowable proportion defective (MAPD)

January 2012

This paper deals with sampling designs on incoming quality MAPD along with a specified probability of acceptance at this point called producer’s allowable risk (PAR). It is defined as the minimum probability of acceptance of the lot with a maximum allowable proportion defective. Tables and graphs are presented, comparing the efficiency of new SSP as to protect AQL. An optimum criterion of sample size...

Wuâ€™s algorithm and its possible application in cryptanalysis

January 2012

In this paper we reviewed Wu’s algorithm and introduced it as a cryptanalysis technique. This study reveals that when Wu’s algorithm is used for cryptanalysis it simplifies. This is true because Wu’s algorithm has to be applied to binary polynomials only, when used for cryptanalysis. To summarize, we gave a full description of Wu’s algorithm in the binary case and also a...

Egoists dilemma with fuzzy data

January 2012

In this paper, we investigate the problems of consensus–making among individuals or organizations with multiple criteria for evaluating performance when the players are supposed to be egoistic and the score for each criterion for a player is supposed to be fuzzy number. We deal with problems with fuzzy parameters from the viewpoint of experts’ imprecise or fuzzy understanding of the...

On three-dimensional generalized sasakian space â€“ forms

January 2012

The object of the present paper is to study locally j –symmetric three-dimensional generalized Sasakian space forms and such manifolds with Ricci semi symmetric, h -parallel Ricci tensor and cyclic Ricci tensor. Such space forms with non-null concircular vector field are also considered. Key words: Generalized sasakian space forms, cosymplectic, locally-j -symmetric, h -parallel ricci...

Department of Applied Mathematics with Oceanology and Computer Programming, Vidyasagar University, Midnapore -- 721102, India

December 2011

In this paper, soft matrices are defined based on soft set. Cartesian product of two soft sets is defined here. The very common operations of soft matrices are defined like AND, OR, union, intersection. commutative, associative, distributive, De Morgan's laws and convergent property for soft matrices are investigated.   Key words:  Soft set, soft relation, soft matrices, AND, OR...

Estimation of temperature distribution and thermal stresses in a thick circular plate

December 2011

A thick circular plate with the arbitrary initial heat flux prescribed on the upper surface is considered and lower and the curved boundary surface are kept at zero temperature. The temperature distribution in the plate is determined by solving heat conduction equation with the help of variable separation technique and then stresses are determined with the help of suitable Michell’s...

Sharon - Agent based service middleware for E-governance: A systematic web examination based approach using Christina ontology

December 2011

Over the past few years, semantic web service and multi agent approach has been used successfully inthe development of E-governance. Such a hybrid approach can be considered as an effective approachfor the development of predictive modeling in complex...

Some common fixed point theorems in D* - metric space

November 2011

In this paper we establish some common fixed point theorems for contraction and generalized contraction mappings in D* - metric space which is introduced by Shaban et al. (2007). In what follows, (X, D*) will denote D* - metric space, N, the set of all natural number and R+, the set of all positive real numbers.   Key words: D* - metric contractive mapping, complete D* - metric space, common...

Formal partitioning analysis and verification of extended algebraic automata

November 2011

Algebraic automata is getting much importance in theoretical computer science because of its various applications, for example, in optimization of programs, verification of protocols, cryptography and modeling biological phenomena. Design of a complex system not only requires functionality but it also needs to capture its control behaviour. This paper is a part of our ongoing research on integration of algebraic...

Entropy and utility based trip distribution model

November 2011

This paper aims to explore the interrelation and equivalence between methods of maximum entropy and utility in establishing the trip distribution model.   Key words: Entropy, utility, trip distribution, Bose–Einstein entropy, Fermi-Dirac entropy.

Solving traveling salesman problem by using a fuzzy multi-objective linear programming

October 2011

The traveling salesman problem (TSP) is one of the most intensively studied problems in computational mathematics. Information about real life systems is often available in the form of vague descriptions. Hence, fuzzy methods are designed to handle vague terms, and are most suited to finding optimal solutions to problems with vague parameters. This study develops a fuzzy multi-objective linear programming...

Optimizing the underground water confined steady flow using a fuzzy approach

October 2011

In this paper we discuss the underground water aquifers, the confined steady flow in homogeneous system where the transmissivities at all nodes inside the zone are represented by the same fuzzy number. A solution algorithm to solve the underground water confined steady flow in homogeneous system (in three dimensions) under fuzziness is considered. The purpose behind this study is to optimize the sum of the...

Characterization of de Bruijn graphs homomorphisms

September 2011

We study homomorphisms between de Bruijn digraphs of different orders. A main theme of this paper is to characterize de Bruijn graph homomorphisms such that the inverse of a factor in the lower order digraph is also a factor in the higher order one, where a factor is a collection of cycles that partition the digraph. We generalize Lempel's homomorphism by describing and characterizing a class of...

On weakly symmetric and weakly Ricci symmetric Lorentzian Para-Sasakian manifolds

September 2011

The aim of the present paper is to study weakly symmetric and weakly Ricci symmetric an LP-Sasakian manifolds and proved that if weakly symmetric LP-Sasakian manifold satisfies -parallel Ricci condition then the scalar curvature of the manifolds is equal to rank of . If weakly symmetric an LP-Sasakian manifolds satisfies Ricci tensor of coddazi type then the manifolds is R-Harmonic, further we have...

Conceptual networks: The role of concept lattices in knowledge management

September 2011

Concepts are defined as couples (O, A) of sets O and A: the object O (a set of none, or one or more elements) is assigned to the set A of these elements’ (common) attributes. The objects change according to the sequence of attributes. Only couples of objects and attributes, that is concepts, are adequate for our world. The connections and links we need in databases and multimedia are expressed, naturally, by...

Optimality of the flexible job shop scheduling problem

September 2011

The flexible job shop scheduling problem is NP-hard problem. There is no efficient technique to check the optimality of the solution of the flexible job shop scheduling problem. So, in this paper, theorems and lemmas for defining some optimality conditions for the solution of the flexible job shop scheduling problem are introduced. In addition, a mathematical model of the primal problem of the flexible job...

Interpolation by quartic splines

September 2011

This paper proposes two special lacunary interpolation problems using quartic splines of continuity class C2. We call the problems (0,3) and (0,4) lacunary interpolation. In these two cases, the third and fourth derivative respectively is also prescribed in between the nodes along with the function value at the nodes. This paper is divided into two parts namely cases A and B. Case A deals with the (0,3)...

Thermal stresses induced by a point heat source in a hollow disk by quasi-static approach

September 2011

This paper deals with the two dimensional non-homogeneous boundary value problem of heat conduction in a hollow disk defined as  and discussed the thermoelastic behavior due to internal heat generation within it. A thin hollow disk is considered having arbitrary initial temperature and subjected to time dependent heat flux at the outer circular boundary  whereas inner circular...

New scrambling algorithm for hiding scanned documents

September 2011

This paper introduces a new technique to hide scanned document in a digital image. It is a one-to-one matching between the pixels from the cover image to the pixel in scanned documents image. The proposed algorithm is an efficient computer-based steganographic method for embedding secret messages into images without producing noticeable changes is implemented. There is no need of referencing the original...

Projective semimodules

September 2011

In this paper, a natural dual of an injective semimodule which was obtained by reversing the arrows in the definition of injective semimodule and replacing epimorphsims with monomorphisms was considered. These new objects are called “projective semimodules”.   Key words: Projective semimodule, epimorphisim, left regular exact sequence, proper exact sequence.

A common fixed point theorem and some fixed point theorems in D*- Metric spaces

August 2011

In this paper we establish some common fixed point theorems for contraction and some generalized contraction mappings in D* - metric space which is introduced by Shaban et al. (2007). In what follows, (X, D*) will denote D* - metric space, N is the set of all natural number and R+ is the set of all positive real number.   Key words: D*- metric, contraction mapping, complete D*- metric...

Some finite integrals involving multivariable polynomials, H-function of one variable and H-function of â€˜râ€™ variables

August 2011

In the present paper we establish the integrals involving the product of two general classes of polynomial, H-function of one variable and H-function of ‘r’ variables.  These integrals are unified in nature and we can derive from them by a large number of integrals involving simpler functions and polynomials as their particular cases.   Key...

MHD Heat transfer aspects between two parallel conducting porous walls in a rotating system, with Hall currents

July 2011

An analysis is presented for heat transfer in fully developed viscous incompressible hydromagnetic flow of an ionized gas bounded by two parallel porous walls under the action of uniform transverse magnetic field, when rotated with an angular velocity about an axis perpendicular to the walls, by taking Hall effect into account. The governing equations of motion and heat transfer expressing the physical...

Mixed type symmetric and self duality for multiobjective variational problems with support functions

July 2011

In this paper, a pair of mixed type symmetric dual multiobjective variational problems containing support functions is formulated. This mixed formulation unifies two existing pairs Wolfe and Mond-Weir type symmetric dual multiobjective variational problems containing support functions. For this pair of mixed type nondifferentiable multiobjective variational problems, various duality theorems are established...

A Branch and Bound approach to a state government capital budgeting

July 2011

The capital budgeting problem is a multi-constraint Knapsack problem. Hence this paper provides a solution to a capital budgeting problem of Akwa Ibom State, Nigeria using a Branch and Bound approach. The capital projects are summarized in four broad groups: The Economic sector (X1), The Social Service sector (X2), The Environmental/Regional Development sector (X3), and...

4th-Step implicit formula for solution of initial value problems of second order ordinary differential equations

July 2011

This paper proposes a direct method of solution for second order initial value problems of ordinary differential equations. Its derivation adopts Taylor series expansion techniques and Dahlquist stability test model. It was revealed from the results obtained that the method is consistent, convergent and zero-stable. Numerical examples are solved to ensure accuracy of the method on both linear and non-linear...

One way functions and public key cryptography

June 2011

The problem faced with symmetric ciphers has always been key exchange. Hellman and Diffie (1976) proposed the idea for key exchange (public key cryptography). Their idea was based on the difficulty in inverting certain mathematical functions; one way functions. The RSA was one of the first practical solutions of key exchange. This paper identifies one way functions and their corresponding public key encryption system,...

The formulation of complex queries and interactions using SMS text messages

June 2011

There is no question that short message service (SMS) has achieved huge success in the wireless world. Billions of SMS text messages are sent every day worldwide. SMS is now a major revenue generator for wireless carriers like expresso and MTN of Ghana. A lot of innovative applications are now built on top of the SMS technology and more are being developed. One of the emerging applications is the use of text...

A new algorithm for static task scheduling for heterogeneous distributed computing systems

June 2011

Effective task scheduling is essential for obtaining high performance in heterogeneous distributed computing systems (HeDCSs). However, finding an effective task scheduling in HeDCSs should take into consideration the heterogeneity of processors and inter-processor communication over head, which results from non-trivial data movement between tasks scheduled on different processors. In this paper, a new high...

Some results on principal ideal graph of a ring

June 2011

Let R be an associative (not necessarily commutative) ring. In the present paper, we introduced a new type of graph (called ‘Principal Ideal Graph’, denoted by PIG(R)) related to a given associative ring R.  We presented some examples. We obtained few fundamental important relations between rings and graphs with respect to the properties: simple ring, complete graph, etc. We also observed...

Asymptotic behavior of solutions of nonlinear delay differential equations with impulse

May 2011

This paper studies the asymptotic behavior of solutions of the second-order nonlinear delay differential equations with impulses:       and   some sufficient conditions are obtained.   Key words: Asymptotic behavior, second-order nonlinear delay differential equation, impulses.

Mathematical model of homogenious tumour growth with delay in time

May 2011

This paper consist of a problem of tumor growth with the function of phosphorous to both tumor cells and healthy cells. A detailed discussion about the growth of healthy cells and tumor cells was observed here. A consideration about the solution part of tumor micro vessels has been made here. The governing equations are than solved using MATLAB (a differential equation solver) and graphs are drawn which show...

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