Mathematics and Physics : [545]

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Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 545
  • The Microstructural Transformation and Dynamical Properties in Sodium-silicate Molecular Dynamics Simulation.pdf.jpg
  • Article


  • Authors: Nguyen, Thi Thanh Ha; Tran, Thuy Duong; Nguyen, Hoai Anh (2020)

  • Molecular dynamics simulation of sodium-silicate has been carried out to investigate the microstructural transformation and diffusion mechanism. The microstructure of sodium silicate is studied by the pair radial distribution function, distribution of SiOx (x=4,5,6), OSiy (y=2,3) basic unit, bond angle distribution. The simulation results show that the structure of sodium silicate occurs the transformation from a tetrahedral structure to an octahedral structure under pressure. The additional network-modifying cation oxide breaking up this network by the generation of non-bridging O atoms and it has a slight effect on the topology of SiOx and OSiy units. Moreover, the diffusion of netw...

  • Study of Structure Transition and Crystallization of Amorphous Silica under Compression.pdf.jpg
  • Article


  • Authors: Giap, Thi Thuy Trang; Pham, Huu Kien (2020)

  • In this work, we use molecular dynamic (MD) simulation to study the structure transition and crystallization of amorphous silica (SiO2) under compression. The structural evolution of amorphous SiO2 is explained through radial distribution function, coordination number distribution, bond angle distribution and visualization. Simulation result shown that there is a structural transformation from tetrahedral to octahedral network through SiO5 units. In the 5-15 GPa pressure range, structural transformation occurs powerfully and there are three structural phases corresponding to SiO4-, SiO5-, and SiO6- ones. At 15 GPa, octahedral-network (SiO6) is dominant. It is the first time we showed ...

  • Optimization of Laminated Composite Plates for Maximum Biaxial Buckling Load.pdf.jpg
  • Article


  • Authors: Pham, Dinh Nguyen; Vu, Quang-Viet; George, Papazafeiropoulos; Hoang, Thị Thiem; Pham, Minh Vuong; Nguyen, Dinh Duc (2020)

  • This paper proposes an optimization procedure for maximization of the biaxial buckling load of laminated composite plates using the gradient-based interior-point optimization algorithm. The fiber orientation angle and the thickness of each lamina are considered as continuous design variables of the problem. The effect of the number of layers, fiber orientation angles, thickness and length to thickness ratios on the buckling load of the laminated composite plates under biaxial compression is investigated. The effectiveness of the optimization procedure in this study is compared with previous works.

  • Investigation on Structure of TeO2-B2O3-SiO2-Al2O3-KF Glasses.pdf.jpg
  • Article


  • Authors: Phan, Van Do (2020)

  • Borotellurite glasses were prepared by melt quenching technique. Amorphous nature of samples was confirmed through X-ray diffraction (XRD) patterns. Effect of B2O3 content on the structure of glass network was studied through Fourier-transform infrared spectroscopy (FTIR) spectra. Optical band gap and Urbach energy were found from analysis of optical absorption spectra. Thermal studies were carried out by using Differential thermal analyzer (DTA) measurements.

  • Effect of Annealing Temperature on Cu2O Thin Films Prepared by Thermal Oxidation Method.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Thi Huyen Trang; Bach, Thanh Cong; Nguyen, Thi Dieu Thu; Nguyen, Thanh Binh; Nguyen, Viet Tuyen; Pham, Nguyen Hai (2020)

  • We report a facile process to fabricate cuprous thin films by thermal oxidation of copper substrates. Structure and phase identification were studied by X-ray diffraction measurement and Raman spectroscopy. Scanning electron microscopy was utilized to study surface morphology of the as-fabricated thin films and optical properties of the samples were investigated by diffused reflectance spectroscopy. The study shows that cuprous thin films could be obtained by controlling annealing temperature in the region of 200-300 oC.

  • 235.pdf.jpg
  • Article


  • Authors: Dang, Minh Triet; Truong, Quoc Tuan; Tran, Van Thien (2020)

  • Colloidal gels are space-spanning networks that form solids at dilute particle volume fractions. The kinetic process of gelation is central to understand the flow of complex fluids. Here, we report a simulation study of colloidal gelation of anisotropic colloids with attractive Lennard-Jones potential. These forces quasi-model the critical Casimir effect far from the critical solvent fluctuations acting on colloidal patches. By tuning the depths of the patch-to-patch particle interactions and the selected colloidal patches, we dynamically arrest the colloids to form gels. We find that thermal density fluctuation is the key factor to activate colloidal cluster space spanning: the balan...

  • 456.pdf.jpg
  • Article


  • Authors: Dao, Quang-Duy (2020)

  • We demonstrate an efficient bulk heterojunction (BHJ) organic solar cell (OSCs) utilizing a soluble phthalocyanine derivative, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2), and a fullerene derivative, 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C71 and roles of processing additive solvent on improvement of the BHJ OSCs. By adding processing additive solvent, filling factor and short-circuit current density are improved to 0.57 and 8.6 mA/cm2, respectively. As a result, the power conversion efficiency of 3.6% is achieved. Otherwise, the effects of processing additive solvent are demonstrated by taking the absorption and photoluminescence spectra of C6PcH2 and composite thin ...

  • 457.pdf.jpg
  • Article


  • Authors: Ngo, Thi Thu Trang; Nguyen, Duc Nhan; Bui, Trung Hieu (2020)

  • In direct-detection optical OFDM system, the nonlinear impairment is the key factor that limits the system performance. The back-propagation techniques in digital and optical domains have been proposed to compensate the nonlinear effects, however they can be unsuitable for long-range passive optical networks (LR-PONs) due to their implementation at receiver. In this study, we propose an optical back propagation (OBP) approach for compensation of the nonlinear and dispersion distortions in direct-detection optical OFDM system. The proposed OBP using split-step Fourier method is implemented at transmitter that is suitable for high-rate OFDM-based LR-PONs applications. In this OBP, the f...

  • 468.pdf.jpg
  • Article


  • Authors: Nguyen, Trong Nghia (2020)

  • C2H5OH has been using as an alternative fuel for decades; HO2 also plays a pivotal role in the combustion. The kinetics and mechanism for the reaction between C2H5OH and HO2 radical have been investigated using the molecular parameters for the reactants, transition states and products predicted at the CCSD(T)//B3LYP/6-311++G(3df,2p) level of theory. There are ten pair products have been found including C2H5O + H2O2 (PR1), CH3CHOH + H2O2 (PR2), CH2CH2OH + H2O2 (PR3), CH3CH2OOOH + H (PR4), C2H5 + HOOOH (PR5), CH3CH2OOH + OH (PR6), CH3CH(OH)OOH + H (PR7), HOCH2CH2OH + H (PR8), HOOCH3 + CH2OH (PR9), and CH3 + HOOCH2OH (PR10) in which the second and third ones are the major channels. The r...

  • 789.pdf.jpg
  • Article


  • Authors: Ho, Thi Anh; Nguyen, Ngoc Huyen; Pham, Duc Thang (2020)

  • Nd0.6Sr0.4MnO3 sample was fabricated by a solid-state reaction method and its magnetic, magnetocaloric properties were investigated. The Curie temperature, TC, at which a ferromagnetic-paramagnetic transition occurred was found to be of about 270 K. An analysis using the Banejee’s criterion of the experiment results for magnetization as a function of temperature and magnetic field and the universal curves of the normalized entropy change versus reduced temperature indicated that the sample undergo the second-order magnetic phase transition. Furthermore, the maximum magnetic entropy change that occurred near TC, measured at a magnetic field span of 50 kOe was found to be of about 6.0 J...

  • 298.pdf.jpg
  • Article


  • Authors: Nguyen, Minh Tan; Chen, Hua-Ming; Giap, Binh Duong; Hoang, Le Quang Nhat (2020)

  • Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) techniques are combined to provide the spectrum efficiency and high data rate improvement that it was required for 4G, 5G wireless systems. Discrete Wavelet Transform (DWT) is presented as an alternative for Fast Fourier Transform (FFT) since there is no necessity for Cyclic Prefix (CP) due to the overlapping properties of DWT. By a simple replacement of the FFT with DWT in MIMO-OFDM system, an improvement of performance has been detected which leads to a new system scenario MIMO-OFDM based on DWT. In this thesis, the two systems are simulated with particular parameters and the performance of B...

  • 452.pdf.jpg
  • Article


  • Authors: Nguyen, Tien Cuong (2020)

  • In this paper, I present first-principle calculations which are performed by using combination of DFT and NEGF methods to investigate the adsorption of CO2 and NH3 molecules on straight and U-shaped GNRs junctions. The density of state, molecular orbital, adsorption energy, transmission spectrum, and current-voltage characteristics were analyzed. It is found that the adsorption of CO2 and NH3 on straight GNRs at the dangling bond edges exhibit chemical interaction behavior with high adsorption energy. Besides, for U-shaped ZGRNs without adsorption, the states around Fermi level are quasi-bound states localized at the zigzag edges. The electrons at these localized states are almost con...

  • 321.pdf.jpg
  • Article


  • Authors: Phung, Thi Viet Bac; Pham, Trong Lam; Dinh, Van An (2020)

  • The adsorption mechanism of 2-butanone (ethyl methyl ketone) on the surface of graphene is investigated by using Density Functionals Theory (DFT). A 2-butanone molecule is chosen as a selected example of main volatile organic compounds (VOCs) in exhaled breath. To describe the absorption of 2-butanone and graphene substrate, we have performed DFT simulations including van de Waals (vdW) interactions implemented in the Vienna Ab-initio Simulation Package (VASP). The global minimum energy configurations and binding energies for a 2-butanone molecule adsorbed on graphene are determined by using Computational DFT-based Nanoscope tool for imaging the binding possibility of the adsorbed mol...

  • 333.pdf.jpg
  • Article


  • Authors: Pham, Trong Lam; Ta, Thi Luong; Vo, Van On; Dinh, Van An (2020)

  • In this work, we investigated the adsorption mechanism of acetone and toluene on the surface of silicene by the quantum simulation method. The images of the potential energy surfaces for different positions of the adsorbate on the silicene surface were explored by Computational DFT-based Nanoscope tool for determination of the most stable configurations and diffusion possibilities. The charge transfer in order of 0.2 – 0.3 electrons and the tunneling gap opening of 18 – 23 meV due to acetone and toluene, respectively, suggest that silicene is considerably sensitive with these VOCs and can be used as the material in the fabrication of reusable VOC sensors.

  • 890.pdf.jpg
  • Article


  • Authors: Nghiem, Thi Minh Hoa; Dang, The Hung; Luong, Minh Tuan; Duong, Xuan Nui; Nguyen, Duc Trung Kien (2020)

  • In an arbitrary system subjected to a quench or an external field that varies the system parameters, the degrees of freedom increases double in comparison to that of an isolated system. In this study, we consider the quantum impurity system subjected to a quench, and measure the corresponding time-evolution of the spectral function, which is originated from the time-resolved photoemission spectroscopy. Due to the large number of degrees of freedom, the expression of the time-dependent spectral function is twice much more complicated than that of the time-independent spectral function, and therefore the calculation is extremely time consuming. In this paper, we estimate the scale of ti...

  • 987.pdf.jpg
  • Article


  • Authors: Nguyen, Thi Thanh Tan; Le, Hong Lam; Nguyen, Ha Nam (2020)

  • The problem of optical character and handwriting recognition has been interested by researchers in long time ago. It has obtained great results in theory as well as practical applications. However, the accuracy of identification is still limited, especially in the case of low-quality input images. In this article, we propose an efficient method to recognize information fields for identification in ID card using Convolutional Neural Network (CNN) and Long Short-Term Memory networks (LSTM). The proposed method was trained in a large, various quality dataset including over three thousands ID card image samples. The implementation achieved better results compare to previous studies with t...

  • 234.pdf.jpg
  • Article


  • Authors: Le, Nhu Thuc; Dao, Thi Le Thuy (2020)

  • The production of scalar unparticle (spin - 0) in the photon - electron ( e )  collider is calculated in all s-, t-, and u-channels in detail as well as interference between channels together. By searching for missing energy distributions as well as evaluating dependence of differential cross section (DCS) on the scattering angle ( ) and cross section (CS) on the center of mass energy ( s ) , we hope that the unparticles production in high energy collider might be detected in future.

  • 123.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Manh Hong; Mai, Hong Hanh; Pham, Van Thanh; Sai, Cong Doanh; Nguyen, Thanh Binh; Pham, Nguyen Hai; Nguyen, Trong Tam; Ho, Khac Hieu; Nguyen, Viet Tuyen (2020)

  • Thanks to unique Raman spectra of chemical substances, a growing number of applications in environmental and biomedical fields based on Raman scattering has been developed. However, the low probability of Raman scattering hindered its potential development and thus, many different techniques were developed to enhance Raman signal. A key step of surface-enhanced Raman scattering technique is to prepare active SERS substrate from noble metals. The main enhancement mechanism is electromagnetic enhancement resulted from surface plasmon resonance. The disadvantages of nanoparticles based SERS substrates include high randomness due to self - assembly process of nanoparticles. Recentl...

  • 4444-97-9269-1-10-20191217.pdf.jpg
  • 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 third-order 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 Fourth-order Runge-Kutta method.

  • 4417-97-9270-1-10-20191217.pdf.jpg
  • 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

Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 545

Mathematics and Physics : [545]

Follow this collection to receive daily e-mail notification of new additions
Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 545
  • The Microstructural Transformation and Dynamical Properties in Sodium-silicate Molecular Dynamics Simulation.pdf.jpg
  • Article


  • Authors: Nguyen, Thi Thanh Ha; Tran, Thuy Duong; Nguyen, Hoai Anh (2020)

  • Molecular dynamics simulation of sodium-silicate has been carried out to investigate the microstructural transformation and diffusion mechanism. The microstructure of sodium silicate is studied by the pair radial distribution function, distribution of SiOx (x=4,5,6), OSiy (y=2,3) basic unit, bond angle distribution. The simulation results show that the structure of sodium silicate occurs the transformation from a tetrahedral structure to an octahedral structure under pressure. The additional network-modifying cation oxide breaking up this network by the generation of non-bridging O atoms and it has a slight effect on the topology of SiOx and OSiy units. Moreover, the diffusion of netw...

  • Study of Structure Transition and Crystallization of Amorphous Silica under Compression.pdf.jpg
  • Article


  • Authors: Giap, Thi Thuy Trang; Pham, Huu Kien (2020)

  • In this work, we use molecular dynamic (MD) simulation to study the structure transition and crystallization of amorphous silica (SiO2) under compression. The structural evolution of amorphous SiO2 is explained through radial distribution function, coordination number distribution, bond angle distribution and visualization. Simulation result shown that there is a structural transformation from tetrahedral to octahedral network through SiO5 units. In the 5-15 GPa pressure range, structural transformation occurs powerfully and there are three structural phases corresponding to SiO4-, SiO5-, and SiO6- ones. At 15 GPa, octahedral-network (SiO6) is dominant. It is the first time we showed ...

  • Optimization of Laminated Composite Plates for Maximum Biaxial Buckling Load.pdf.jpg
  • Article


  • Authors: Pham, Dinh Nguyen; Vu, Quang-Viet; George, Papazafeiropoulos; Hoang, Thị Thiem; Pham, Minh Vuong; Nguyen, Dinh Duc (2020)

  • This paper proposes an optimization procedure for maximization of the biaxial buckling load of laminated composite plates using the gradient-based interior-point optimization algorithm. The fiber orientation angle and the thickness of each lamina are considered as continuous design variables of the problem. The effect of the number of layers, fiber orientation angles, thickness and length to thickness ratios on the buckling load of the laminated composite plates under biaxial compression is investigated. The effectiveness of the optimization procedure in this study is compared with previous works.

  • Investigation on Structure of TeO2-B2O3-SiO2-Al2O3-KF Glasses.pdf.jpg
  • Article


  • Authors: Phan, Van Do (2020)

  • Borotellurite glasses were prepared by melt quenching technique. Amorphous nature of samples was confirmed through X-ray diffraction (XRD) patterns. Effect of B2O3 content on the structure of glass network was studied through Fourier-transform infrared spectroscopy (FTIR) spectra. Optical band gap and Urbach energy were found from analysis of optical absorption spectra. Thermal studies were carried out by using Differential thermal analyzer (DTA) measurements.

  • Effect of Annealing Temperature on Cu2O Thin Films Prepared by Thermal Oxidation Method.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Thi Huyen Trang; Bach, Thanh Cong; Nguyen, Thi Dieu Thu; Nguyen, Thanh Binh; Nguyen, Viet Tuyen; Pham, Nguyen Hai (2020)

  • We report a facile process to fabricate cuprous thin films by thermal oxidation of copper substrates. Structure and phase identification were studied by X-ray diffraction measurement and Raman spectroscopy. Scanning electron microscopy was utilized to study surface morphology of the as-fabricated thin films and optical properties of the samples were investigated by diffused reflectance spectroscopy. The study shows that cuprous thin films could be obtained by controlling annealing temperature in the region of 200-300 oC.

  • 235.pdf.jpg
  • Article


  • Authors: Dang, Minh Triet; Truong, Quoc Tuan; Tran, Van Thien (2020)

  • Colloidal gels are space-spanning networks that form solids at dilute particle volume fractions. The kinetic process of gelation is central to understand the flow of complex fluids. Here, we report a simulation study of colloidal gelation of anisotropic colloids with attractive Lennard-Jones potential. These forces quasi-model the critical Casimir effect far from the critical solvent fluctuations acting on colloidal patches. By tuning the depths of the patch-to-patch particle interactions and the selected colloidal patches, we dynamically arrest the colloids to form gels. We find that thermal density fluctuation is the key factor to activate colloidal cluster space spanning: the balan...

  • 456.pdf.jpg
  • Article


  • Authors: Dao, Quang-Duy (2020)

  • We demonstrate an efficient bulk heterojunction (BHJ) organic solar cell (OSCs) utilizing a soluble phthalocyanine derivative, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2), and a fullerene derivative, 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C71 and roles of processing additive solvent on improvement of the BHJ OSCs. By adding processing additive solvent, filling factor and short-circuit current density are improved to 0.57 and 8.6 mA/cm2, respectively. As a result, the power conversion efficiency of 3.6% is achieved. Otherwise, the effects of processing additive solvent are demonstrated by taking the absorption and photoluminescence spectra of C6PcH2 and composite thin ...

  • 457.pdf.jpg
  • Article


  • Authors: Ngo, Thi Thu Trang; Nguyen, Duc Nhan; Bui, Trung Hieu (2020)

  • In direct-detection optical OFDM system, the nonlinear impairment is the key factor that limits the system performance. The back-propagation techniques in digital and optical domains have been proposed to compensate the nonlinear effects, however they can be unsuitable for long-range passive optical networks (LR-PONs) due to their implementation at receiver. In this study, we propose an optical back propagation (OBP) approach for compensation of the nonlinear and dispersion distortions in direct-detection optical OFDM system. The proposed OBP using split-step Fourier method is implemented at transmitter that is suitable for high-rate OFDM-based LR-PONs applications. In this OBP, the f...

  • 468.pdf.jpg
  • Article


  • Authors: Nguyen, Trong Nghia (2020)

  • C2H5OH has been using as an alternative fuel for decades; HO2 also plays a pivotal role in the combustion. The kinetics and mechanism for the reaction between C2H5OH and HO2 radical have been investigated using the molecular parameters for the reactants, transition states and products predicted at the CCSD(T)//B3LYP/6-311++G(3df,2p) level of theory. There are ten pair products have been found including C2H5O + H2O2 (PR1), CH3CHOH + H2O2 (PR2), CH2CH2OH + H2O2 (PR3), CH3CH2OOOH + H (PR4), C2H5 + HOOOH (PR5), CH3CH2OOH + OH (PR6), CH3CH(OH)OOH + H (PR7), HOCH2CH2OH + H (PR8), HOOCH3 + CH2OH (PR9), and CH3 + HOOCH2OH (PR10) in which the second and third ones are the major channels. The r...

  • 789.pdf.jpg
  • Article


  • Authors: Ho, Thi Anh; Nguyen, Ngoc Huyen; Pham, Duc Thang (2020)

  • Nd0.6Sr0.4MnO3 sample was fabricated by a solid-state reaction method and its magnetic, magnetocaloric properties were investigated. The Curie temperature, TC, at which a ferromagnetic-paramagnetic transition occurred was found to be of about 270 K. An analysis using the Banejee’s criterion of the experiment results for magnetization as a function of temperature and magnetic field and the universal curves of the normalized entropy change versus reduced temperature indicated that the sample undergo the second-order magnetic phase transition. Furthermore, the maximum magnetic entropy change that occurred near TC, measured at a magnetic field span of 50 kOe was found to be of about 6.0 J...

  • 298.pdf.jpg
  • Article


  • Authors: Nguyen, Minh Tan; Chen, Hua-Ming; Giap, Binh Duong; Hoang, Le Quang Nhat (2020)

  • Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) techniques are combined to provide the spectrum efficiency and high data rate improvement that it was required for 4G, 5G wireless systems. Discrete Wavelet Transform (DWT) is presented as an alternative for Fast Fourier Transform (FFT) since there is no necessity for Cyclic Prefix (CP) due to the overlapping properties of DWT. By a simple replacement of the FFT with DWT in MIMO-OFDM system, an improvement of performance has been detected which leads to a new system scenario MIMO-OFDM based on DWT. In this thesis, the two systems are simulated with particular parameters and the performance of B...

  • 452.pdf.jpg
  • Article


  • Authors: Nguyen, Tien Cuong (2020)

  • In this paper, I present first-principle calculations which are performed by using combination of DFT and NEGF methods to investigate the adsorption of CO2 and NH3 molecules on straight and U-shaped GNRs junctions. The density of state, molecular orbital, adsorption energy, transmission spectrum, and current-voltage characteristics were analyzed. It is found that the adsorption of CO2 and NH3 on straight GNRs at the dangling bond edges exhibit chemical interaction behavior with high adsorption energy. Besides, for U-shaped ZGRNs without adsorption, the states around Fermi level are quasi-bound states localized at the zigzag edges. The electrons at these localized states are almost con...

  • 321.pdf.jpg
  • Article


  • Authors: Phung, Thi Viet Bac; Pham, Trong Lam; Dinh, Van An (2020)

  • The adsorption mechanism of 2-butanone (ethyl methyl ketone) on the surface of graphene is investigated by using Density Functionals Theory (DFT). A 2-butanone molecule is chosen as a selected example of main volatile organic compounds (VOCs) in exhaled breath. To describe the absorption of 2-butanone and graphene substrate, we have performed DFT simulations including van de Waals (vdW) interactions implemented in the Vienna Ab-initio Simulation Package (VASP). The global minimum energy configurations and binding energies for a 2-butanone molecule adsorbed on graphene are determined by using Computational DFT-based Nanoscope tool for imaging the binding possibility of the adsorbed mol...

  • 333.pdf.jpg
  • Article


  • Authors: Pham, Trong Lam; Ta, Thi Luong; Vo, Van On; Dinh, Van An (2020)

  • In this work, we investigated the adsorption mechanism of acetone and toluene on the surface of silicene by the quantum simulation method. The images of the potential energy surfaces for different positions of the adsorbate on the silicene surface were explored by Computational DFT-based Nanoscope tool for determination of the most stable configurations and diffusion possibilities. The charge transfer in order of 0.2 – 0.3 electrons and the tunneling gap opening of 18 – 23 meV due to acetone and toluene, respectively, suggest that silicene is considerably sensitive with these VOCs and can be used as the material in the fabrication of reusable VOC sensors.

  • 890.pdf.jpg
  • Article


  • Authors: Nghiem, Thi Minh Hoa; Dang, The Hung; Luong, Minh Tuan; Duong, Xuan Nui; Nguyen, Duc Trung Kien (2020)

  • In an arbitrary system subjected to a quench or an external field that varies the system parameters, the degrees of freedom increases double in comparison to that of an isolated system. In this study, we consider the quantum impurity system subjected to a quench, and measure the corresponding time-evolution of the spectral function, which is originated from the time-resolved photoemission spectroscopy. Due to the large number of degrees of freedom, the expression of the time-dependent spectral function is twice much more complicated than that of the time-independent spectral function, and therefore the calculation is extremely time consuming. In this paper, we estimate the scale of ti...

  • 987.pdf.jpg
  • Article


  • Authors: Nguyen, Thi Thanh Tan; Le, Hong Lam; Nguyen, Ha Nam (2020)

  • The problem of optical character and handwriting recognition has been interested by researchers in long time ago. It has obtained great results in theory as well as practical applications. However, the accuracy of identification is still limited, especially in the case of low-quality input images. In this article, we propose an efficient method to recognize information fields for identification in ID card using Convolutional Neural Network (CNN) and Long Short-Term Memory networks (LSTM). The proposed method was trained in a large, various quality dataset including over three thousands ID card image samples. The implementation achieved better results compare to previous studies with t...

  • 234.pdf.jpg
  • Article


  • Authors: Le, Nhu Thuc; Dao, Thi Le Thuy (2020)

  • The production of scalar unparticle (spin - 0) in the photon - electron ( e )  collider is calculated in all s-, t-, and u-channels in detail as well as interference between channels together. By searching for missing energy distributions as well as evaluating dependence of differential cross section (DCS) on the scattering angle ( ) and cross section (CS) on the center of mass energy ( s ) , we hope that the unparticles production in high energy collider might be detected in future.

  • 123.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Manh Hong; Mai, Hong Hanh; Pham, Van Thanh; Sai, Cong Doanh; Nguyen, Thanh Binh; Pham, Nguyen Hai; Nguyen, Trong Tam; Ho, Khac Hieu; Nguyen, Viet Tuyen (2020)

  • Thanks to unique Raman spectra of chemical substances, a growing number of applications in environmental and biomedical fields based on Raman scattering has been developed. However, the low probability of Raman scattering hindered its potential development and thus, many different techniques were developed to enhance Raman signal. A key step of surface-enhanced Raman scattering technique is to prepare active SERS substrate from noble metals. The main enhancement mechanism is electromagnetic enhancement resulted from surface plasmon resonance. The disadvantages of nanoparticles based SERS substrates include high randomness due to self - assembly process of nanoparticles. Recentl...

  • 4444-97-9269-1-10-20191217.pdf.jpg
  • 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 third-order 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 Fourth-order Runge-Kutta method.

  • 4417-97-9270-1-10-20191217.pdf.jpg
  • 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

Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 545