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Search Results: 1 - 10 of 2532 matches for " Mehdi Sadatgol "
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Plasmon Injection to Compensate and Control Losses in Negative Index Metamaterials
Mehdi Sadatgol,?ahin K. ?zdemir,Lan Yang,Durdu ?. Güney
Physics , 2015, DOI: 10.1103/PhysRevLett.115.035502
Abstract: Metamaterials have introduced a whole new world of unusual materials with functionalities that cannot be attained in naturally occurring material systems by mimicking and controlling the natural phenomena at subwavelength scales. However, the inherent absorption losses pose fundamental challenge to the most fascinating applications of metamaterials. Based on a novel plasmon injection (PI or \Pi) scheme, we propose a coherent optical amplification technique to compensate losses in metamaterials. Although the proof of concept device here operates under normal incidence only, our proposed scheme can be generalized to arbitrary form of incident waves. The \Pi-scheme is fundamentally different than major optical amplification schemes. It does not require gain medium, interaction with phonons, or any nonlinear medium. The \Pi-scheme allows for loss-free metamaterials. It is ideally suited for mitigating losses in metamaterials operating in the visible spectrum and is scalable to other optical frequencies. These findings open the possibility of reviving the early dreams of making 'magical' metamaterials from scratch.
Magneto-optical metamaterial
Mehdi Sadatgol,Mahfuzur Rahman,Ebrahim Forati,Miguel Levy,Durdu O. Guney
Physics , 2015,
Abstract: We propose a new class of metamaterials called magneto-optical metamaterials that offer enhanced angle of rotation in polarization compared to bulk magneto-optical materials. In the proposed approach, the permittivity tensor of a magneto-optical material is tailored by embedded wire meshes behaving as artificial plasma. We have shown that the angle of rotation in the magneto-optical metamaterial can be enhanced up to 9 times compared to bulk magneto-optical material alone while the polarization extinction ratio remains below -20dB and insertion loss is less than 1.5dB.
A simple 2D interpolation model for analysis of nonlinear data  [PDF]
Mehdi Zamani
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.26080
Abstract: To determination the volume and weight of non uniform bodies, such as in ore deposits evaluation for mining and rock cutting for construction, the methods of interpolation are usually used. The classic curves, which are frequently used to interpolate onedimensional data are cubic spl ine, Bspline and Bezier curves. These methods have good efficiency for determination of geom etric characteristics of nonregular masses. They have some limitations and problems with two dimensional interpolation analysis such as for ming large linear systems of equations with a lot of entries and difficulty encounter with their solutions. In this research the twodimensional splines are used, which have the advantages of simplicity and less computational operations ef fort. The spline functions that are applied have the continuity of C1 at elements boundaries. The presented model has suitable efficiency for vo lumes of large extents governing to lots of data.
Application of He’s Variational Iteration Method and Adomian Decomposition Method to Solution for the Fifth Order Caudrey-Dodd-Gibbon (CDG) Equation  [PDF]
Mehdi Safari
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.28131
Abstract: In this work we use the He’s variational iteration method and Adomian decomposition method to solution N-soliton solutions for the fifth order Caudrey-Dodd-Gibbon (CDG) Equation.
Analytical Solution of Two Extended Model Equations for Shallow Water Waves By Adomian’S Decomposition Method  [PDF]
Mehdi. Safari
Advances in Pure Mathematics (APM) , 2011, DOI: 10.4236/apm.2011.14042
Abstract: In this paper, we consider two extended model equations for shallow water waves. We use Adomian’s decomposition method (ADM) to solve them. It is proved that this method is a very good tool for shallow water wave equations and the obtained solutions are shown graphically.
Application of He’s Variational Iteration Method for the Analytical Solution of Space Fractional Diffusion Equation  [PDF]
Mehdi Safari
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.29150
Abstract: Spatially fractional order diffusion equations are generalizations of classical diffusion equations which are increasingly used in modeling practical super diffusive problems in fluid flow, finance and others areas of application. This paper presents the analytical solutions of the space fractional diffusion equations by variational iteration method (VIM). By using initial conditions, the explicit solutions of the equations have been presented in the closed form. Two examples, the first one is one-dimensional and the second one is two-dimensional fractional diffusion equation, are presented to show the application of the present techniques. The present method performs extremely well in terms of efficiency and simplicity.
A simple piecewise cubic spline method for approximation of highly nonlinear data  [PDF]
Mehdi Zamani
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.41012
Abstract: Approximation methods are used in the analysis and prediction of data, especially laboratory data, in engineering projects. These methods are usually linear and are obtained by least-square-error approaches. There are many problems in which linear models cannot be applied. Because of that there are logarithmic, exponential and polynomial curve-fitting models. These nonlinear models have a limited application in engineering problems. The variation of most data is such that the nonlinearity cannot be approximated by the above approaches. These methods are also not applicable when there is a large amount of data. For these reasons, a method of piecewise cubic spline approximation has been developed. The model presented here is capable of following the local nonuniformity of data in order to obtain a good fit of a curve to the data. There is C1 continuity at the limits of the piecewise elements. The model is tested and examined with four problems here. The results show that the model can approximate highly nonlinear data efficiently.
Numerical Investigation of the Effect of Process and Sheet Parameters on Bending Angle in the Laser Bending Process  [PDF]
Mehdi Safari
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.44011
Abstract:

In this work, the effects of process parameters such as laser output power, beam diameter and scan speed and also sheet thickness on the bending angle have been numerically investigated in the laser bending process. For this purpose, Abaqus software is used for investigating the effect of various process and sheet parameters on the bending angle. The results show that with increasing the laser output power, bending angle is increased. Also, the bending angle is decreased with increasing the beam diameter, scan speed and sheet thickness.

Using GIS Data to Build Informed Virtual Geographic Environments (IVGE)  [PDF]
Mehdi Mekni
Journal of Geographic Information System (JGIS) , 2013, DOI: 10.4236/jgis.2013.56052
Abstract:

In this paper, we propose a novel approach to automatically building Informed Virtual Geographic Environments (IVGE) using data provided by Geographic Information Systems (GIS). The obtained IVGE provides 2D and 3D geographic information for visualization and simulation purposes. Conventional VGE approaches are generally built upon a grid-based representation, raising the well-known problems of the lack of accuracy of the localized data and the difficulty to merge data with multiple semantics. On the contrary, our approach uses a topological model and provides an exact representation of GIS data, allowing an accurate geometrical exploitation. Moreover, our model can merge semantic information, even if spatially overlapping. In addition, the proposed IVGE contains spatial information which can be enhanced thanks to a geometric abstraction method. We illustrate this model with an application which automatically extracts the required data from standard GIS files and allows a user to navigate and retrieve information from the computed IVGE.

 

Relationships, Human Behaviour and Financial Transactions  [PDF]
Mehdi Chowdhury
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.49108
Abstract: It is widely known that relationships and human behaviours such as trust, reciprocity and altruism that are observed in the human societies are capable of facilitating financial transactions. This paper proposes a theoretical model to argue that though these elements can facilitate financial transactions, they may not always ensure efficiency in the sense of creation of additional wealth. As financial resources are scarce, the paper argues that the financial transactions induced by relationships, trust, reciprocity and altruism may lead to inefficient allocations of resources.
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