Time filter

Source Type

Yerevan, Armenia

The State Engineering University of Armenia is a technical university located in Yerevan, Armenia. Established as the Yerevan Polytechnic Institute in 1933, it provides educational and research programs in various fields of technology and science related to engineering. Currently there are more than 10,000 students and more than 900 faculty members. Wikipedia.

Vorobiev A.,Chalmers University of Technology | Gevorgian S.,Chalmers University of Technology | Martirosyan N.,State Engineering University of Armenia | Loffler M.,Chalmers University of Technology | Olsson E.,Chalmers University of Technology
Applied Physics Letters | Year: 2012

Intrinsically tunable 0.67BiFeO3-0.33BaTiO3 (BF-BT) thin film bulk acoustic wave resonators with record high tunability of 4.4 and effective electromechanical coupling coefficient of 10 are fabricated and analyzed. The analysis, based on the theory of the dc field induced piezoelectric effect with the mechanical loading by the electrodes taken into account, reveals that the enhanced parameters are associated with the inherently high BF-BT electrostriction coefficient, which is found to be 5.9 × 1010 m/F. The Q-factor of the BF-BT resonators is up to 220 at 4.1 GHz and is limited mainly by acoustic wave scattering at reflection from a relatively rough top interface. © 2012 American Institute of Physics.

Abrahamian R.M.,State Engineering University of Armenia
Journal of Contemporary Physics | Year: 2010

It is shown that the efficiency of a regenerative Stirling cycle can principally not reach that of a Carnot cycle operating in the same temperature range. A relation is obtained between the degree of regeneration and the characteristics of regenerator. The maximum efficiency of an ideal regenerative Stirling engine is obtained. © 2010 Allerton Press, Inc.

Aharonyan K.H.,State Engineering University of Armenia
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The spatial and time dependencies of the dielectric function for the quasi-two dimensional (Q2D) electron gas (EG) in a finite confining potential quantum well (QW) are calculated by using a self-consistent approach (SQF). Taking into account the influences of mismatch of strong discontinuous dielectric constant and effective masse across the interfaces the dielectric response function analytic expressions are derived for a rectangular finite potential barrier QW for the first time. The deviations from the results when these mismatches are absent are established. By using exactly calculated dielectric function a comparison with the respective asymptotic expressions of finite and infinite confining models is presented both analytically and numerically on the base of realistic EuS/PbS/EuS QW. The transition interval between 2D and 3D cases has been demonstrated numerically. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Harutyunyan V.A.,State Engineering University of Armenia
Physics of the Solid State | Year: 2010

The single-electron states in a quantized cylindrical layer in the presence of a strong homogeneous electric field have been considered in the isotropic effective mass approximation. The energy spectrum and the envelope wave functions of charge carriers in the layer have been obtained in the explicit form. It has been shown that a strong external electric field leads to an additional localization of carriers in their angular motion. The corresponding selection rules have been derived, and the absorption band of intraband-intersubband optical transitions in the layer has been calculated. © 2010 Pleiades Publishing, Ltd.

Aharonyan K.H.,State Engineering University of Armenia
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

In the framework of two-band envelope-function formalism the binding energy and ground state radius of an exciton in a EuS/PbS/EuS finite confining potential quantum well (QW) are calculated analytically by using a variational approach. By taking into account the effective masses mismatch across the interfaces and anisotropic carrier masses in the QW, the initial deviation from the result of an infinite confining potential QW is derived. The influence of strong discontinuous dielectric constants and nonparabolic mirror bands is fully evaluated by using the coupling between QW longitudinal and transversal carrier motions. The correlations of the quantum, dielectric, barrier mass and nonparabolicity effects in the exciton binding energy are determined. A comparison with the respective quantities of two confining models is presented. © 2010 Elsevier B.V.

Discover hidden collaborations