In this article, Laplace transform and new homotopy perturbation methods are adopted to study the problem of forced convection over a horizontal flat plate analytically. The problem is a system of nonlinear ordinary differential equations which arises in boundary layer flow. The solutions approximated by the proposed method are shown to be precise as compared to the corresponding results obtained by numerical method. A high accuracy of new method is evident.

In this paper, the technique of modified decomposition method is used to solve a system of linear integro-differential equations with initial conditions. Moreover, two particular examples are discussed to show relability and the performance of the modified decomposition method.

A set \(S\) of points in graph \(G\) is a neighborhood set if \(G=\cup_{\nu\in S}\langle N[\nu]\rangle\) where \(\langle N[\nu]\rangle\) is the subgraph of \(G\) induced by \(\nu\) and all points adjacent to \(\nu\). The neighborhood number, denoted \(n_0(G)\), of \(G\) is the minimum cardinality of a neighborhood set of \(G\). In this paper, we study the neighborhood number of certain graphs.

Waste heat recovery is very important, because not only it reduces the expenditure of heat generation, but also it is of high priority in environmental consideration, such as reduction in greenhouse gases. One of the devices is used in waste heat recovery is thermosyphon heat exchanger (THE). In this paper, theoretical research has been carried out to investigate the thermal performance of an air to air thermosyphon heat exchanger. This purpose is done by solving simultaneous principles equations. It was found that with implementation of targeted subsides plan in Islamic Republic of Iran, saving in gas oil consumption is very considerable by using this device.

In this paper for solving nonlinear system of mixed Volterra-Fredholm integral equations by using variational iteration method, we have used differentiation for converting problem to suitable form such that it can be useful for constructing a correction functional with general lagrange multiplier. The optimum of lagrange multiplier can be found by variational theorem and by choosing of restrict variations properly. By substituting of optimum lagrange multiplier in correction functional, we obtain convergent sequences of functions and by appropriate choosing initial approximation, we can get approximate of the exact solution of the problem with few iterations. Some applications of nonlinear mixed Volterra-Fredholm integral equations arise in mathematical modeling of the Spatio-temporal development of an epidemic. So nonlinear system of mixed Volterra-Fredholm integral equations is important and useful. The above method independent of small parameter in comparison with similar works such as perturbation method. Also this method does not require discretization or linearization. Accuracy of numerical results show that the method is very effective and it is better than Adomian decomposition method since it has faster convergence and it is more simple. Also this method has a closed form and avoids the round of errors for finding approximation of the exact solution. The looking forward the proposed method can be used for solving various kinds of nonlinear problems.

In this study, an application of differential transform method (DTM) is applied to solve the second kind of nonlinear integral equations such that Volterra and Fredholm integral equations. If the equation considered has a solution in terms of the series expansion of known function, this powerful method catches the exact solution. Comparison is made between the homotopy perturbation and differential transform method. The results reveal that the differential transform method is very effective and simple.

Capital market contains different sectors and one of its important sectors is currency market. High turnover in this market has attracted many investors. In this article an efficient system of recognizing point of buy and sell is invented with the help of fuzzy logic. In suggested model functions of triangular and trapezoidal membership is used for defining linguistic variables which can be used for symbol of Euro - Dollar. Inventing system based on fuzzy logic is the first one of its type and its direct application in Forex indicates its efficiency in the real world which can be used in developed trading expert systems for exchange market.

Convex optimization has provided both a powerful tool and an intriguing mentality to the analysis and design of communication systems over the last few years. This paper presents the results of investigation on dual bounds for nonconvex quadratic programming with a nonlinear constraint and an overview of the nonconvex optimization problem in the networked communication systems.

First, an extension of Pontryagin Maximum Principle in Infinite-Horizon, which was presented by Aseev and Kryazhimiskii, is explained. Since this method is applicable in optimal economical growth problems, for the first time several problems such as consumption and investment are solved. Moreover, for implementing Aseev and Kryazhimiskii 's method on Iranian economy, Luis Serven model is introduced. Then it is calibrated on Iranian economy during the years 1385-1415. By applying the described method, the optimal consumption and investment for maximizing the social welfare are demonstrated. Also the sensitivity analysis is discussed.

Regarding increase of wireless network application, and fast development at these systems, security in such systems and networks has become a crucial matter. In this article, first different security methods of local wireless networks, as subsidiaries of wireless networks, are introduced and then the efficiency of so far introduced security methods such as WEP, WPA and WPAv2 are studied as well as their negative and positive aspects. The focus of this text is on IEEE security protocols including 802.1x and 802.11i, their functions and security levels. The privileges and shortcoming at the mentioned protocols would be discussed afterwards.

In this article the problem of two-dimensional viscous flow between slowly expanding or contracting walls with weak permeability is presented and Homotopy Perturbation Method (HPM) is employed to compute an approximation to the solution of the system of nonlinear differential equations governing the problem. Comparisons are made between the Numerical solution (NM) and the results of the He's Homotopy Perturbation Method (HPM).

The Fredholm and Volterra types of integral equations are appeared in many engineering fields. In this paper, we suggest a method for solving Fredholm and Volterra integral equations of the first kind based on the wavelet bases. The Haar, continuous Legendre, CAS, Chebyshev wavelets of the first kind (CFK) and of the second kind (CSK) are used on [0,1] and are utilized as a basis in Galerkin or collocation method to approximate the solution of the integral equations. In this case, the integral equation converts to the system of linear equations. Then, in some examples the mentioned wavelets are compared with each other.