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Ladopoulos E.G.,Interpaper Research Organization
Forschung im Ingenieurwesen/Engineering Research | Year: 2012

The coupling of the Singular Integral Operators Method (SIOM) and the Finite Element Method (FEM) is proposed and investigated for the solution of plate bending problems. Such combination of the above two numerical methods gives more accurate results for the solution of plate bending problems in structural analysis. The plates are basic units of building frame structures, as well as to underground structures and thus the determination of bending moments around the plates is very important for the analysis of all kinds of structures. An application of plate bending problems is finally given to the determination of the bending moments in a rectangular plate with a rectangular hole in the center of the plate. © Springer-Verlag 2012.


Ladopoulos E.G.,Interpaper Research Organization
Archives of Mechanics | Year: 2013

A two-dimensional unsteady cascade aeroelasticity is introduced for the in- vestigation of flow fields of turbomachines (gas or steam). Especially, the velocity field around a cascade of airfoils is determined, while such a problem is reduced to the solution of a non-linear multidimensional singular integral equation when con- sidering harmonic time dependence between the motions of adjacent blades of the turbine. Consequently, a general non-linear model is investigated by proposing an "innovative" and " groundbreaking" method. An application is finally presented by considering a special description of the velocity field and therefore such a field is determined for arbitrary geometry and arbitrary interblade phase angle. Copyright © 2013 by IPPT PAN.


Ladopoulos E.G.,Interpaper Research Organization
International Journal of Renewable Energy Research | Year: 2013

A new theory is proposed and investigated by using intermediate bands within the energy gap of the semiconductor, in order to increase the efficiency of solar cells. Thus, the photons with energy less than the band gap could contribute to the output device by using the intermediate band or bands, in order to jump to the conduction band. Such a problem is reduced to the solution of non-linear integral equations and for their solution an innovative and groundbreaking numerical method is proposed. Generally, in solar cells low energy photons can not excite electrons to the conduction band and then to the external circuit. In addition, intermediate bands get advantage of the lower energy photons by allowing the electrons to be promoted to levels in the usually forbidden energy gap. Consequently, through such a multi-step approach, then the efficiency of the solar cell is increasing. In the current investigation we will show that the maximum efficiency of an ideal solar cell containing one and two intermediate bands will be 63 % and 75 %, respectively.


Ladopoulos E.G.,Interpaper Research Organization
Acta Mechanica | Year: 2011

A new mathematical model is proposed in order to determine the properties of the reservoir materials, when oil reserves are moving through porous media, which is a very important problem of petroleum reservoir engineering. Thus, the above problem is reduced to the solution of a non-linear singular integral equation, which is numerically evaluated by using the singular integral operators method (SIOM). Also, several properties of the porous medium equation, which is a Helmholtz differential equation, are analyzed and investigated. An application is finally given for a well testing to be checked when an heterogeneous oil reservoir is moving in a porous medium. By using the SIOM, the pressure response from the well test conducted in the above heterogeneous oil reservoir is calculated. © 2011 Springer-Verlag.


Ladopoulos E.G.,Interpaper Research Organization
International Journal of Non-Linear Mechanics | Year: 2011

A two-dimensional aerodynamics representation analysis is introduced for the investigation of inviscid flowfields of unsteady airfoils. The problem of the unsteady flow of a two-dimensional NACA airfoil is therefore reduced to the solution of a non-linear multidimensional singular integral equation, when the form of the source and vortex strength distribution is dependent on the history of the above distribution on the NACA airfoil surface. An application is given to the determination of the velocity and pressure coefficient field around an aircraft by assuming constant source distribution. © 2011 Elsevier Ltd. All rights reserved.


Ladopoulos E.G.,Interpaper Research Organization
International Journal of Oil, Gas and Coal Technology | Year: 2012

By using a non-linear 3-D elastic waves real-time expert system, the new theory of 'real-time expert seismology' is proposed, for the exploration of the on-shore and off-shore oil and gas reserves all over the world. This highly innovative and groundbreaking technology is working under real time logic for searching the on-shore and off-shore petroleum reserves developed on the continental crust and in deeper water ranging from 300 m to 2,500 m, or even deeper. Furthermore, for the determination of the properties of the reservoir materials, when oil reserves mixed with water in multiphase flows are moving through porous media, a new mathematical device is proposed. The above problem is very much important for petroleum reservoir engineering and the oil industry. Hence, such a problem is reduced to the solution of a non-linear singular integral equation, which is numerically evaluated by using the singular integral operators method (SIOM). Also, several properties are analysed and investigated for the porous medium equation, defined as a Helmholtz differential equation. [Received: February 28, 2012; Accepted: March 18, 2012]. Copyright © 2012 Inderscience Enterprises Ltd.


Ladopoulos E.G.,Interpaper Research Organization
International Journal of Acoustics and Vibrations | Year: 2014

Based on the new theory of Real-Time Expert Seismology, a non-linear 3-D elastic wave real-time expert system is used for the exploration globa on-shore and off-shore petroleum and gas reserves. This highly innovative and ground-breaking technology uses elastic (seismic) waves moving in an unbounded subsurface medium to searching the on-shore and off-shore hydrocarbon reserves developed on the continental crust and in deeper water ranging from 300 to 3000+ m. This modern technology can be used in any depth of sea, in oceans all over the world, and for any depth in the subsurface of existing oil and gas reserves. Furthermore, the various mechanical properties of the rock regulating the wave propagation phenomenon appear as spatially-varying coefficients in a system of time-dependent hyperbolic partial differential equations. The propagation of the seismic waves through the earth subsurface is described by the wave equation, which is finally reduced to a Helmholz differential equation. Then the Helmholtz differential equation is numerically evaluated by using the Singular Integral Operators Method (SIOM). Also, several properties are analysed and investigated for the wave equation. Finally, an application is proposed for the determination of the seismic field radiated from a pulsating sphere into an infinite homogeneous medium. The acoustic pressure radiated from the above pulsating sphere is determined by the SIOM.


Ladopoulos E.G.,Interpaper Research Organization
Water Resources | Year: 2013

The design of a non-linear real-time expert water management telematics system is proposed, in order to minimize the waste of 15% to 40% of the water supplies in the ground pipe networks, because of the leakage. This expert system will work by using the step testing method, and it will be therefore possible to determine the approximate location of leakage for every big urban area. Furthermore, ARC/INFO Geographic Information Systems (GIS) working under the UNIX-operating system in X-Windows are used in the Workstation of the Central Station (CS) in order to handle data. The proposed real-time expert system will be non-linear in its responses and a part of the programming language will be fourth generation real-time software working under real-time logic. © 2013 Pleiades Publishing, Ltd.


Ladopoulos E.G.,Interpaper Research Organization
Computers and Fluids | Year: 2010

The free-surface profile of potential flows is calculated in open-channel transitions by using singular integral equation methods. Thus in such free-surface hydraulics applications the analysis of fluid motion is very complicated, as both the subcritical and supercritical flows are presented simultaneously. For the numerical solution of the singular integral equations are used both constant and linear elements.An application is finally given to the determination of the free-surface profile in an open-channel contraction and comparing the numerical results with corresponding results by finite differences. © 2010 Elsevier Ltd.

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