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Danang, Vietnam

Duy Tân University is a private university in Da Nang, Vietnam. The name derives from the Modernisation Movement, or phong trào Duy Tân, of 1906-1908. Wikipedia.

In this paper, we analyze the impact of hardware impairments at relay node and source node (i.e. imperfect nodes) on network performance by evaluating outage probability based on the effective signal to noise and distortion ratio (SNDR). Especially, we propose energy harvesting protocol at the relay and source nodes, namely, power switching imperfect relay (PSIR) and power switching imperfect source (PSIS). Aiming to determine the performance of energy constrained network, we first derive closed-form expressions of the outage probability and then the throughput can be maximized in delay-limited transmission mode. The simulation results provide practical insights into the impacts of hardware impairments and power switching factors of the energy harvesting protocol on the performance of energy harvesting enabled two-way relaying network. Source

Doan Quoc K.,Duy Tan University
Optical and Quantum Electronics

We consider Raman ring laser by modeling the laser pump light by a classical time-dependent random process, namely a pre-Gaussian process. It is composed of a finite number of independent so-called telegraphs. The strength of the pre-Gaussian formalism derives from the exact solubility of wide classes of the stochastic equations. In particular we also observed the so-called noise reduction in Raman ring laser: the Stokes output of this laser tends to the stabilize under the influence of the broad-band one-telegraph pre-Gaussian pump (Cao Long and Doan Quoc in Opt Quant Electron 43:137–145, 2012). We extend our model to the case of two-telegraph pre-Gaussian noise and compare obtained results with that obtained in our previous paper for the case of broad-band one-telegraph pre-Gaussian pump. © 2016, Springer Science+Business Media New York. Source

Tuan L.A.,Duy Tan University | Lee S.-G.,Kyung Hee University
Journal of Mechanical Science and Technology

This study focuses on the design of robust nonlinear controllers based on both conventional and hierarchical sliding mode techniques for double-pendulum overhead crane systems. In the first approach, a first-order sliding surface is provided and a proper control scheme is generated to stabilize the surface. In the second approach, two levels of sliding surfaces are proposed and the control scheme is designed based on the stability of the second-level surface. We also prove the stability of the first-level sliding surface. To verify the quality of the proposed controllers, simulation for a particular type of overhead crane systems is implemented. Simulation results show that all state trajectories asymptotically converged to desired values. © 2013 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg. Source

Nguyen S.T.,Euro Engineering | Nguyen S.T.,Duy Tan University
Journal of Applied Geophysics

The objective of this work is to employ the micromechanical approach for the modeling of the electrical resistivity and of the conductivity of sandstone. This type of rock is considered as a mixture of solid mineral and porous space filled fully or partially by conductive water. The Eshelby's solution of a spheroidal inclusion in a homogeneous matrix is employed. The differential effective medium model (DEM) with different concepts of the microstructure is developed for the calculation of the resistivity. The parametric study clarifies the impact of the microscopic parameters on the macroscopic electrical properties. The simulations are compared with the classical empirical and theoretical approaches as well as with the laboratory measurements. The results show a strong impact of the microstructure (the shape of the pore, the presence of non-conductive fluids in the pore space, the connectivity of conductive fluid) on the macroscopic resistivity and conductivity of sandstone. This approach gives a link between the microscopic physical parameters of the rock and the macroscopic electrical parameters such as the cementation exponent and the electrical formation factor. © 2014 Elsevier B.V. Source

Hung Phan Q.,Duy Tan University
Advanced Nonlinear Studies

We study Liouville-type theorem for polyharmonic H'enon-Lane-Emden system (-▵)mu = |x|avp, (-▵)mv = |x|buq when m, p, q ≥ 1, pq ≥ 1, and a, b ≥ 0. It is a natural conjecture that the nonexistence of positive solutions should be true if and only if (N + a)/(p + 1)+ (N + b)/(q + 1) > N - 2m. It is shown by Fazly[6] that the conjecture holds for radial solutions in all dimensions and for classical solutions in dimension N ≤ 2m + 1. We here give some partial results in dimension N ≥ 2m + 2. Source

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