 Article
Authors: Vu, Minh Anh; Nguyen, Dinh Duc (2019)  The nonlinear dynamic response and vibration of the porous functionally graded cylindrical panel (PFGCP) subjected to the thermal load, mechanical load and resting on elastic foundations are determined by an analytical approach as the Reddy’s thirdorder shear deformation theory, Ahry’s function… The results for dynamic response of PFGCP present the effect of geometrical ratio, elastic foundations: Winkler foundation and Paskternak foundation, loads: mechanical load and thermal load, the material properties and distribution type of porous. The results are shown as numerical results, figures and are determined by using Galerkin methods and Fourthorder RungeKutta method.

 Article
Authors: Nguyen, Thu Ha (2019)  This paper is concerned with the robust stability for implicit dynamic equations on time scales, which is a general form of differential algebraic equations and implicit difference equations. We show the reservation of exponential stability of these equations under small Lipschitz perturbations

 Article
Authors: Nguyen, Quang Bau; Doan, Minh Quang; Tran, Hai Hung (2019)  Based on the quantum kinetic equation for electrons, we have theoretically studied the influence of a Strong Electromagnetic Wave (EMW) on the MagnetoThermoelectric Effects in a cylindrical quantum wire with an infinite potential (CQWIP) (for electron  optical phonon scattering) under the influence of electric field E1=(0,0,E1), magnetic field B=(0,B,0) and a strong EMW (laser radiation) E= (0,0,E0sinΩt) (where and are amplitude and frequency of EMW, respectively). We obtain the analytic expressions for the kinetic tensors sik, bik, gik, xik and the Ettingshausen coefficient (EC) in the CQWIP with the dependence on the frequency, the amplitude of EMW, the Quantum Wire (CQWIP) para...

 Article
Authors: Hoang, Huu Duc; Nguyen, Duc Minh; Phan, Viet Cuong; Le, Toan Anh; Leuangtakoun, Somsavath; Bui, Van Loat (2019)  The soiltoplant transfer factors of natural uranium isotopes (238U and 232Th) were studied in Luong My tea farm, Tan Thanh district, Luong Son commune, HoaBinh province. The activity concentrations in leaves, trunk and root were determined for the tea tree at no harvest period (winter break). The measurements were carried out using gamma spectroscopy with high puritygermanium detector HPGe. Research results show that the activity of 238U and 232Th is higher in leaves than in trunk and roots.Soilleaves transfer factor (TF) for238U and 232Th were as follows:TFU238 = 0,52 – 0,87; TFTh232 = 0,25 – 0,43.

 Article
Authors: Nguyen, Thi Hong; Ho, Khac Hieu (2019)  Statistical moment method (SMM) has been applied in combination with Lindemann melting criterion to investigate pressure effects on melting temperature of iron. Melting curves of phase with bodycentered cubic structure and phase with facecentered cubic structure of iron have been derived up to pressure 13 GPa and 90 GPa, respectively. This work shows that melting curves of these two phases of iron are increasing functions of pressure, and the higher the pressure is the lower the slopes of melting curves are. Our results are compared with those of available experimental data to verify the developed theory. The efficiency of the SMM on the investigation of melting temperatures of a...

 Article
Authors: Nguyen, Thi Hau; Dao, Thi Le Thuy (2019)  We study the production of Higgs and vector unparticle which has been proposed as an option of muy+muy collision by s, t, uchannels in the RandallSundrum model (RSM). The crosssection(CS) is presented and numerical evaluation is detailed. Calculations of the crosssection indicate that the crosssection increases fastly as 1.8

 Article
Authors: Tran, Thi Ngoc Anh; Tran, Thi Ha; Nguyen, Viet Tuyen; Pham, Nguyen Hai (2019)  This paper presents results of preparation of Ag doped ZnO bulk sample by solid state reaction and Ag doped ZnO thin films by sputtering method. Effect of doping concentration (1, 2 and 4%) on the properties of the thin films was investigated. Various methods were utilized to investigate characteristics of the samples: Xray diffraction, Raman scattering spectroscopy, photoluminescence, energy dispersive XRay spectroscopy, scanning electron microscopy, atomic force microscope, absorption spectroscopy and Hall measurement. The results show that Ag diffused into ZnO crystal lattice after heat treatment at 1200oC. Asprepared thin film samples exhibit low resistivity in the order of 10...

 Article
Authors: Le, Minh Hieu; Truong, Thi Hieu Hanh; Dang, Ngoc Hoang Thanh (2019)  We develop unconditionally monotone nitedifference schemes of secondorder of local approxi
mation on uniform grids for the initial boundary problem value for the Gamma equation. Twoside
estimates of the solution of the scheme are established. We consider the initial boundary value
problem for the so called Gamma equation, which can be derived by transforming the nonlinear
BlackScholes equation for option price into a quasilinear parabolic equation for the second derivative
of the option price, and for its exact solution the twoside estimates are obtained. By means of regu
larization principle, the previous results are generalized for construction of unconditionally monoto...

 Article
Authors: Pham, Tri Dung; Nguyen, Quang Bau; Nguyen, Thi Thu Ha; Mai, Thi Lan (2019)  The paper presents research results of structure of the Mullite system (3Al2O3.2SiO2) by Molecular Dynamics simulation (MDs) using the Born–Mayer– Huggins pair interaction and periodic boundary conditions. The simulation is performed with model of 5250 atoms at different pressure and at 3500 K temperature. The structural properties of the system have been clarified through analysis of the pair radial distribution function, the distribution of coordination number, the bond angle and the link between adjacent TOx units.

 Article
Authors: Nguyen, Dinh Lam (2019)  PbS quantum dots were coated on the surface of single junction GaAs solar cells by a drop coating method. The thickness of PbS quantum dot layer was controlled through changing the number of coating layers. The influences of PbS coating layers on characteristics of GaAs single junction solar cells were investigated through IV characteristic measurements, optical reflectance spectra, and quantum efficiencies. The results indicated that, the shortcircuit current can be improved up to 15% with two PbS coating layers. Other parameters such as Voc and FF are hardly affected by the number of PbS coating layers. Based on the results of optical reflectance spectra and quantum efficiencies, ...

 Article
Authors: Phan, Van Do (2019)  Dy3+ doped alumino borotellurite (ABT) glasses xB2O3+(80x)TeO2+10Al2O3+10CaO+ 0.5Dy2O3 (where x = 35; 45 and 55) have been prepared by melting method. Their optical properties were studied through absorption, luminescence spectra and decay time measurements. JuddOfelt (JO) intensity parameters (Ωλ, λ = 2, 4 and 6) have been determined using absorption spectra and are been used to calculate the radiative parameters like transition probability, stimulated emission crosssection, branching ratios, gain band width and optical gain for the 4F9/2→6H13/2 transition in Dy3+ ions. The chromaticity coordinates is used to estimate the emission feature of prepared glasses

 Article
Authors: Nguyen, Khac Man; Nguyen, Duc Hoa; Duong, Thi Thanh Nhan (2019)  HighTc superconducting polycrystalline Bi2223 undoped sample (A0) and 5wt.% Agdoped sample (A5) have been prepared by solidstate reaction method at 8550C with sintering time of 8 days. Xray powder diffraction (XRD) results shown that the major phase of these samples is Bi2223. The volume ratio of Bi2223 phase observed to be increased from 78% for undoped sample (A0) to 95% for 5wt.% Agdoped sample (A5). The enhancement of the onset of highTc superconductivity (Tc,onset = 112.5 K) in silver doping sample was observed by DCresistivity measurements. From the ACsusceptibility measurements combined with Bean critical state model, the temperature dependent parabolic law of inter...

 Article
Authors: Trinh, Thi Loan; Nguyen, Ngoc Long (2019)  The SnO2:Ni2+ powders with dopant contents ranging from 0.0 to 12 mol% have been synthesized by solgel method. The samples were characterized by Xray diffraction (XRD) Raman spectroscopy, energydispersive Xray spectrometer (EDS) and photoluminescense (PL) spectra. XRD analysis showed that samples doped with low Ni concentrations exhibited single SnO2 crystalline phase, whereas the samples with high Ni concentrations exhibited a mixture of SnO2 and NiO phases. The lattice parameters of the SnO2 host were independent on Ni2+ dopant content, while Raman mode positions were dependenton Ni2+ dopant content. The PL spectrum of the undoped SnO2 was characterized by the emission peaks d...

 Article
Authors: Pham, Huu Kien; Pham, Mai An; Nguyen, Hong Linh; Giap, Thuy Trang (2019)  The FeB nanoparticle (NP) consisting of 5000 particles (4500 Fe atoms and 500 B
atoms) has been investigated by means of molecular dynamics (MD) simulation. When the
amorphous FeB nanoparticle is annealed at temperature of 900 K for a long time, it is crystallized
into bcc crystalline structure. The simulation shows that the sample undergoes crystallization via
the nucleation mechanism. During the crystallization, B atoms diffuse to the boundary region of Fe
crystal. The crystal growth proceeds when this boundary region attains specific properties which
are defined by the fraction of B atoms and the energies of ABatoms and CBatoms. Further our
study indicates that the crystal...

 Article
Authors: Nguyen, Thi Thanh Ha (2019)  Molecular dynamic simulation is employed to study the structural properties and
diffusion mechanism in sodium silicate (Na2O.4SiO4). Structural characteristics are clarified through
the pair radial distribution function, distribution of SiOx coordination units, network structure. The
simulation results reveal that the structure of Na2O.4SiO4 liquid consists of one SiO network that
is mainly formed by SiO4 units. The spatial distribution of sodium is nonuniform; sodium tends to
be in the nonbridging oxygensimplexes and in largerradius simplex. Moreover, the sodium
density for nonbridging oxygen region is significantly higher than the one for others region. Further,
we find...

 Article
Authors: Pham, Ngoc Thang; Le, Thai Hung; Do, Tuan Long; Nguyen, Quang Bau (2019)  The influence of confined acoustic phonons on the Hall Coefficient (HC) in a Cylindrycal
Quantum Wire (CQW) with an infinite potential (for electron – confined acoustic phonons
scattering). Consider a case where CQW is placed in a perpendicular magnetic field �⃗ , a constant 
electric field � ⃗⃗⃗⃗1 and an intense electromagnetic wave �⃗ = � ⃗⃗⃗⃗0 ��� Ω�. By using the quantum kinetic
equation for electrons interacting with Confined Optical Phonon (COP), we obtain analytical
expressions for (HC), which are different from in comparison to those obtained for the HC in the
case of normal bulk semiconductor and in the case of cylindrycal quantum wire with electron –
unconfined phono...

 Article
Authors: Dao, Thu Hang; Nguyen, Thi Hoa; Nguyen, Thi Thanh Nhan; Nguyen, Quang Bau (2019)  Ettingshausen coefficient (EC) in the compositional semiconductor superlattice (CSSL)
under the influence of electromagnetic wave (EMW) is surveyed by using the quantum kinetic
equation for electrons. The analytical expressions of the Ettingshausen coefficient are numerically calculated for the GaAs/AlGaAs compositional semiconductor superlattice. It have been showed that the appearance of EMW has changed the EC’s value and the EC decreases nonlinearly when the temperature increases. Studying the dependence of EC on the magnetic field, we discovered that the superlattice period strongly affects the quantum magneto  thermoelectric effect. When the superlattice period is small, the q...

 Article
Authors: Trinh, Tuan Anh; Bui, Thi Hang (2019)  To find a suitable material for Feair battery anode, Fe2O3 nanoparticles (nm) and
microparticles (µm) were used as active materials and Acetylene Black carbon (AB) as additive to
prepare Fe2O3/AB composites. The effect of grain size of iron oxide particles and additives on the
electrochemical behavior of Fe2O3/AB composite electrodes in alkaline solution have been
investigated using cyclic voltammetry (CV), galvanostatic cycling and electrochemical impedance
spectroscopy (EIS) measurements. Iron oxide nanoparticles provided better cyclability than iron
oxide microparticles. Impedance of electrode increased during cycling but the nmFe2O3/AB
electrode gave smaller resistance th...

 Article
Authors: Khuc, Van Phu; Le, Xuan Doan; Nguyen, Van Thanh (2019)  In this paper, the governing equations of rectangular plates with variable thickness
subjected to mechanical load are established by using the classical plate theory, the geometrical
nonlinearity in von KarmanDonnell sense. Solutions of the problem are derived according to
Galerkin method. Nonlinear dynamic responses, critical dynamic loads are obtained by using
RungeKutta method and the Budiansky–Roth criterion. Effect of volumefraction index k and
some geometric factors are considered and presented in numerical results.

 Article
Authors: Nguyen, Dinh Duc (2019)  This research demonstrates an analytical method for investigation vibration and dynamic
response of plates structure which made from 2Dimensional (2D) pentagraphene. The density
functional theory is used to figure out the elastic modulus of single layer pentagraphene. The
classical plate theory is applied to determine basic equations of 2D pentagraphene composite plates.
The numerical results obtained using the BubnovGalerkin method and RungKutta method. The
results in this research showed high agreement when it is compared with the other study. The results
demonstrate the effect of shape parameters, material properties, foundation parameters, the
mechanical load on the n...
