مجله بین المللی ریاضیات صنعتی
سال:1388 | دوره: | شماره: |تعداد مقالات:8

A model of the equations of two-dimensional problems is studied in a half space, whose surface in a medium free of micropolar thermoelastic possesses cubic symmetry as a result of inclined load. There acts an initial magnetic field parallel to the plane boundary of the half-space.The inclined load is assumed to be a linear combination of a normal load and a tangential load. The formulation is performed in the context of the Lord-Shulman and Green-Lindsay theories, as well as the classical dynamical coupled theory. Comparisons are made with the results in the presence of a magnetic.

In this paper, the fuzzy partial differential equation is investigated by using the strongly generalized differentiability concept. The alternating direction implicit (ADI) method is proposed for approximating the solution of the two-dimensional heat equation where the initial and boundary conditions are fuzzy numbers. The algorithm is illustrated by solving several examples.

A new model of the equations of generalized thermoelasticiy for a material of the cylinder which is supposed to be homogeneous isotropic thermally conducting is given. The formulation is applied in the context of Green and Naghdi (GN) theory of types II and III under the effect of rotation. The problem has been solved numerically using a finite element method. Numerical results for the temperature distribution, displacement, radial stress, and hoop stress are represented graphically. The results indicate that the effect of rotation was very pronounced. Comparisons are made with the results predicted by the types II and III in the presence and absence of rotation. The results obtained in this paper can be used to design various homogeneous thermoelastic elements under thermal load to meet special engineering requirements.

A practical direct method to compute numerical solutions of the linear Volterra and Fredholm integral equations system is proposed. This approach is based on vector forms of triangular functions and its operational matrices and without any integration reduces an integral equations system to a system of algebraic equations. Numerical results of some examples show that the method is practical and has high accuracy.

In this paper, we study the numerical solution of hybrid fuzzy differential equations by using the improved predictor-corrector (IPC) three step method. We state the convergence and stability of this method. Numerical examples will be presented to illustrate this method.

In this paper, the researcher proposes a modified new method to rank L-R fuzzy numbers.The modified method uses a defuzzification of parametrically represented fuzzy numbers that have been studied in [20]. This parameterized defuzzification can be used as a crisp approximation with respect to a fuzzy quantity. In this article, the researcher uses this defuzzification for ordering fuzzy numbers. The modified method can effectively rank various fuzzy numbers and their images and overcome the shortcomings of the previous techniques. This study also uses some comparative examples to illustrate the advantages of the proposed method.

In the pharmaceutical industry, a great number of products are in the form of particulate solids. Since the mid-1980s, a new method of powder generation has appeared involving crystallisation with supercritical fluids (SCF). The rapid expansion of supercritical solutions (RESS) is a promising new process for the production of small and uniform particles.Several variables can influence the RESS process: the nozzle temperature, preexpansion pressure, the nozzle diameter, and geometry. In this work, a two-dimensional Lagrange interpolation method has been proposed to describe the size of nanoparticle forming through the rapid expansion of supercritical solutions, as a function of preexpansion pressure and nozzle temperature.

The current paper presents a mathematical programming model for use to the measure of efficiency where multiple performance measures are needed to examine the performance and productivity changes. In many applications of data envelopment analysis (DEA), the existing models are designed to obtain a single efficiency measure. However, in many real situations, the units under consideration may perform several different functions or can be separated into different components. In these cases, some inputs are often shared among those components and all components are involved in producing some outputs and all components have exclusive inputs and outputs. Therefore, measuring the efficiency of each component and measuring the aggregated efficiency of each unit are important.In this paper, car factories' efficiency is analyzed using data from 19 car factories in Iran.First, a DEA-efficiency analysis of multi-component DMUs, which proposed by Cook et al is presented and then by using a "common set of weights (csw)", a new model is proposed to measure the efficiency of each component and aggregated efficiency of units. One of the most important advantages of this model is that by solving only one linear programming problem all efficiency measures may be obtained. Secondly, by grouping the branches according to their organizational designation, their efficiency is measured.