the strength of concrete is a function of the proportions of the constituent materials, namely, cement, water, fine and coarse aggregates. the conventional methods used to determine the mix proportions that will yield the desired strength, are laborious, time consuming and expensive. in this paper, a mathematical method based on modified regression theory is formulated for the prediction of con...

in this study a series of ambient vibration tests on the triple ferrocement elevated water tanks with 150 cubic meters volume, is carried out. in order to verify the dynamic characteristics of full, half-full and one full tanks (mass eccentric system), the different arrangements of sensors are used. the effects of base rotation are also considered in the tests. natural frequencies and mode shap...

the advent of e-commerce has prompted many manufacturers to redesign their traditional channel structure by engaging in direct sales. in this paper, we present a dual channel inventory model based on queuing theory in a manufacturer-retailer supply chain, consisting of a traditional retail channel and a direct channel which stocks are kept in both upper and lower echelon. the system receives st...

in this paper, the experimental method of caustics and its application to stress field and related studies in fracture mechanics is described. theocaris [1,2,3] has used the optical method of caustics to study stress intensity factors and the stress field around crack tips, in cracked transparent plates. many other researchers have also used this method to obtain stress intensity factors for di...

In this paper, a new fractional sub-equation method is proposed for finding exact solutions of fractional partial differential equations (FPDEs) in the sense of modified Riemann-Liouville derivative. With the aid of symbolic computation, we choose the space-time fractional Zakharov-Kuznetsov-Benjamin-Bona-Mahony (ZKBBM) equation in mathematical physics with a source to illustrate the validity a...

the pupose of this paper is modeling of partial digest problem (pdp) as a mathematical programming problem. in this paper we present a new viewpoint of pdp. we formulate the pdp as a continuous optimization problem and develope a method to solve this problem. finally we constract a linear programming model for the problem with an additional constraint. this later model can be solved by the simp...

fuzzy linear programming problem occur in many elds such as mathematical modeling, control theory and management sciences, etc. in this paper we focus on a kind of linear programming with fuzzy numbers and variables namely fully fuzzy linear programming (fflp) problem, in which the constraints are in inequality forms. then a new method is proposed to ne the fuzzy solution for solving (fflp). ...

bubble column reactors are used in a wide variety of applications such as multiphase bioreactors, catalytic slurry reactors, and absorption processes. the superficial gas velocity-gas holdup relationship and transition point are two important parameters for characterizing the hydrodynamics of a bubble column reactor. in this study, systematic investigation of a nitrogen - water - glass beads bu...

in this paper, modified simple equation method has been applied to ob-tain generalized solutions of burgers, huxley equations and combined forms of these equations. the new exact solutions of these equations have been obtained. it has been shown that the proposed method provides a very effective, and powerful mathematical tool for solving nonlinear partial differential equations.