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Vu Van Hung - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the Ionic Conductivities of Yttria-Doped Ceria and Yttria-Stabilized Zirconia by Using the Statistical Moment Method
Journal of the Korean Physical Society, 2019Co-Authors: Le Thu Lam, Vu Van Hung, Bui Duc TinhAbstract:The ionic conductivities of yttria-doped ceria (YDC) and yttria-stabilized zirconia (YSZ), are investigatied using Statistical Moment method including the anharmonicity effects of thermal lattice vibrations. The expressions for the lattice constant and the vacancy activation energy are derived in closed analytic forms in terms of the power Moments of the atomic displacements. The distribution of oxygen vacancies around dopants and the important role of cation barriers on vacancy diffusion are evaluated in detail. The lattice constants, activation energies, ionic conductivities of YDC and YSZ are calculated as functions of the dopant concentration. Notably, the ionic conductivities depend linearly on dopant concentration. Our results are in good agreement with those of both previous experiments and several theoretical calculations.
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Investigation of Thermodynamic Properties of Zirconia Thin Films by Statistical Moment Method
Materials Sciences and Applications, 2018Co-Authors: Vu Van Hung, Le Thi Thanh Huong, Dang Thanh HaiAbstract:The Moment method in Statistical (SMM) dynamics is used to study the thermodynamic quantities of ZrO2 thin films taking into account the anharmonicity effects of the lattice vibrations. The average lattice constant, thermal expansion coefficient and specific heats at the constant volume of ZrO2 thin films are calculated as a function of temperature, pressure and thickness of thin film. SMM calculations are performed using the Buckingham potential for the ZrO2 thin films. In the present study, the influence of temperature, pressure and the size on the thermodynamic quantities of ZrO2 thin film have been studied using three different interatomic potentials. We discuss temperature and thickness dependences of some thermodynamic quantities of ZrO2 thin films and we compare our calculated results with those of the experimental results.
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Investigation of elastic moduli and constants of zinc-blende Al y Ga 1- y As alloy by Statistical Moment method
The European Physical Journal B, 2018Co-Authors: Vu Van Hung, Duong Dai Phuong, Tran Xuan Linh, Ho Khac HieuAbstract:The elastic moduli and elastic constants of the ternary semiconductor alloy Al y Ga1-yAs at finite temperature have been investigated using the Statistical Moment method. The Young, shear, bulk moduli and elastic constants C11, C12, C44 of the zinc-blende Al y Ga1−yAs crystal are calculated as functions of Al composition and temperature. Numerical calculations have been performed and compared with those of the experimental and other theoretical results showing the reasonable agreements. Our study shows that elastic moduli and C11, C12 constants of zinc-blende Al y Ga1−yAs alloy are decreasing functions of the temperature and Al composition; C44 constant is a decreasing function of the Al composition.
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Investigation of thermodynamic and mechanical properties of AlyIn1−yP alloys by Statistical Moment method
Physica B: Condensed Matter, 2018Co-Authors: Vu Van Hung, Tran Thi Hai, Pham Thi Minh Hanh, Nguyen Viet Tuyen, Ho Khac HieuAbstract:Abstract The thermodynamic and mechanical properties of III-V zinc-blende AlP, InP semiconductors and their alloys have been studied in detail from Statistical Moment method taking into account the anharmonicity effects of the lattice vibrations. The nearest neighbor distance, thermal expansion coefficient, bulk moduli, specific heats at the constant volume and constant pressure of the zincblende AlP, InP and AlyIn1−yP alloys are calculated as functions of the temperature. The Statistical Moment method calculations are performed by using the many-body Stillinger-Weber potential. The concentration dependences of the thermodynamic quantities of zinc-blende AlyIn1−yP crystals have also been discussed and compared with those of the experimental results. Our results are reasonable agreement with earlier density functional theory calculations and can provide useful qualitative information for future experiments. The Moment method then can be developed extensively for studying the atomistic structure and thermodynamic properties of nanoscale materials as well.
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investigation of thermodynamic and mechanical properties of alyin1 yp alloys by Statistical Moment method
Physica B-condensed Matter, 2017Co-Authors: Vu Van Hung, Tran Thi Hai, Pham Thi Minh Hanh, Nguyen Viet Tuyen, Ho Khac HieuAbstract:Abstract The thermodynamic and mechanical properties of III-V zinc-blende AlP, InP semiconductors and their alloys have been studied in detail from Statistical Moment method taking into account the anharmonicity effects of the lattice vibrations. The nearest neighbor distance, thermal expansion coefficient, bulk moduli, specific heats at the constant volume and constant pressure of the zincblende AlP, InP and AlyIn1−yP alloys are calculated as functions of the temperature. The Statistical Moment method calculations are performed by using the many-body Stillinger-Weber potential. The concentration dependences of the thermodynamic quantities of zinc-blende AlyIn1−yP crystals have also been discussed and compared with those of the experimental results. Our results are reasonable agreement with earlier density functional theory calculations and can provide useful qualitative information for future experiments. The Moment method then can be developed extensively for studying the atomistic structure and thermodynamic properties of nanoscale materials as well.
Kinichi Masuda-jindo - One of the best experts on this subject based on the ideXlab platform.
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Calculation of Elastic Constants of Cubic Metals by Statistical Moment Method: Temperature Dependence
Journal of the Physical Society of Japan, 2008Co-Authors: Vu Van Hung, Kinichi Masuda-jindo, Nguyen Thi HoaAbstract:The elastic properties of cubic metals have been studied using the analytic free energy formulas derived from the quantum Statistical Moment method (SMM). The three independent elastic constants C 11 , C 12 , and C 44 of cubic metals are calculated as a function of the temperature taking into account the anharmonicity of thermal lattice vibrations, and compared with the available experimental results. The particular attention has been paid to the understanding of the anharmonicity effects of thermal lattice vibrations on the elastic properties and thermodynamic crystalline stabilities of the metals in comparison with those by classical treatments of SMM.
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Application of Statistical Moment Method to Thermodynamic Properties and Phase Transformations of Metals and Alloys
Solid State Phenomena, 2008Co-Authors: Kinichi Masuda-jindo, Vu Van Hung, Patrice E. A. TurchiAbstract:The thermodynamic properties and phase transformations of metals and alloys are studied using the Statistical Moment method, going beyond the quasi-harmonic approximations. Including the power Moments of the atomic displacements up to the fourth order, the Helmholtz free energies and the related thermodynamic quantities are derived explicitly in closed analytic forms. The thermodynamic quantities, like thermal lattice expansion coefficients, specific heats, Gruneisen constants, elastic constants calculated by using the SMM are compared with those of other theoretical schemes and the experimental results. The hcp-bcc structural phase transformations observed for IVB elements, Ti, Zr and Hf, are discussed in terms of the anharmonicity of thermal lattice vibrations. The equilibrium phase diagrams are calculated for the refractory Ta-W and Mo-Ta bcc alloys. In addition, the temperature dependence of the elastic moduli C11, C12 and C14 and those of the ideal tensile and shear strengths of the bcc elements Mo, Ta and W are studied: We also discuss the melting transitions of metals and alloys within the framework of the SMM and estimate the melting temperatures through the limiting temperature of the crystalline stability.
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Study of ideal strengths of metals and alloys by Statistical Moment method: Temperature dependence
Journal of Materials Research, 2007Co-Authors: Vu Van Hung, Kinichi Masuda-jindo, Nguyen Thi HoaAbstract:The ideal strengths of metals and alloys at finite temperatures have been studied using the Statistical Moment method. The tensile and shear strengths of the body-centered cubic (bcc) transition metals like Mo and W (refractory metals), and ordered FeA1 (B2) and Fe3Al (DO3) alloys are calculated as a function of the temperature. The orthogonal tight-binding method is used for bcc transition elements, while the universal binding-energy relation (UBER)-type of pairwise potentials, derived from ab initio density- functional theory, is used for the FeAl and Fe3Al alloys. We discuss the temperature dependence of the tensile and shear strengths of the metals and alloys in conjunction with those of the second-order elastic constants. © 2007 Materials Research Society. Index Keywords: Density functional theory; Shear strength; Statistical methods; Tensile strength; Thermal effects; Transition metals; Body-centered cubic; Second-order elastic constant; Statistical Moment method; Temperature dependence; Universal binding-energy relation; Metal testing
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First principles study of tantalum thermodynamics by the Statistical Moment method
Computational Materials Science, 2006Co-Authors: Vu Van Hung, Kinichi Masuda-jindo, Jaichan Lee, Leejun KimAbstract:Abstract The thermodynamic properties of bcc tantalum are studied using the analytic Statistical Moment method and the first principles PAW–LDA (projector augmented wave method with local density approximation) scheme. The equation of states at finite temperatures are derived taking into account the anharmonicity effects of thermal lattice vibrations. The calculated thermodynamic quantities of bcc Ta crystals are in good agreement with the experimental results.
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Investigation of thermodynamic properties of cerium dioxide by Statistical Moment method
Journal of Physics and Chemistry of Solids, 2006Co-Authors: Vu Van Hung, Jaichan Lee, Kinichi Masuda-jindoAbstract:Abstract The thermodynamic properties of the cerium dioxide (CeO 2 ) are studied using the Statistical Moment method, including the anharmonicity effects of thermal lattice vibrations. The free energy, linear thermal expansion coefficient, bulk modulus, specific heats at the constant volume and those at the constant pressure, C V and C P , are derived in closed analytic forms in terms of the power Moments of the atomic displacements. The temperature dependence of the thermodynamic quantities of cerium dioxide is calculated using three different interatomic potentials. The influence of dipole polarization effects on the thermodynamic properties and thermodynamic stability of cerium dioxide have been studied in detail.
Yong Xia - One of the best experts on this subject based on the ideXlab platform.
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Statistical Moment-based structural damage detection method in time domain
Earthquake Engineering and Engineering Vibration, 2013Co-Authors: Jing Zhang, Yong XiaAbstract:A novel structural damage detection method with a new damage index, i.e., the Statistical Moment-based damage detection (SMBDD) method in the frequency domain, has been recently proposed. The aim of this study is to extend the SMBDD method in the frequency domain to the time domain for building structures subjected to non-Gaussian and non-stationary excitations. The applicability and effectiveness of the SMBDD method in the time domainis verified both numerically and experimentally. Shear buildings with various damage scenarios are first numerically investigated in the time domain taking into account the effect of measurement noise. The applicability of the proposed method in the time domain to building structures subjected to non-Gaussian and non-stationary excitations is then experimentally investigated through a series of shaking table tests, in which two three-story shear building models with four damage scenarios aretested. The identified damage locations and severities are then compared with the preset values. The comparative results are found to be satisfactory, and the SMBDD method is shown to be feasible and effective for building structures subjected to non-Gaussian and non-stationary excitations.
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Generalization of the Statistical Moment-based damage detection method
Structural Engineering and Mechanics, 2011Co-Authors: Jun Zhang, Yong XiaAbstract:A novel structural damage detection method with a new damage index has been recently proposed by the authors based on the Statistical Moments of dynamic responses of shear building structures subject to white noise ground motion. The Statistical Moment-based damage detection (SMBDD) method is theoretically extended in this paper with general application. The generalized SMBDD method is more versatile and can identify damage locations and damage severities of many types of building structures under various external excitations. In particular, the incomplete measurements can be considered by the proposed method without mode shape expansion or model reduction. Various damage scenarios of two general forms of building structures with incomplete measurements are investigated in consideration of different excitations. The effects of measurement noise are also investigated. The damage locations and damage severities are correctly identified even when a high noise level of 15% and incomplete measurements are considered. The effectiveness and versatility of the generalized SMBDD method are demonstrated.
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Experimental investigation on Statistical Moment-based structural damage detection method
Structural Health Monitoring: An International Journal, 2009Co-Authors: Jun Zhang, Yong XiaAbstract:Although vibration-based structural damage detection methods have demonstrated various degrees of success, the damage detection of civil structures still remains as a challenging task. The main obstacles include the insensitivity to local damage and the high sensitivity to measurement noise. A new structural damage detection method based on the Statistical Moments of dynamic responses of a structure has been recently proposed by the authors, and the numerical study manifested that the proposed method is sensitive to local structural damage but insensitive to measurement noise. The experimental investigation on this method is presented in this article. Three shear building models with and without damage were built and subjected to ground motions generated by a shaking table. The displacement and acceleration responses of each building model at each floor were recorded. The recorded ground motion and building responses as well as identified structural damping ratios were then used to identify damage locatio...
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Statistical Moment-based damage detection of building structures
2009Co-Authors: Jun Zhang, Yong XiaAbstract:4th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2009, Zurich, 22-24 July 2009
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Further development of Statistical Moment-based damage detection method
2009Co-Authors: Jun Zhang, Yong XiaAbstract:6th International Conference on Advances in Steel Structures and Progress in Structural Stability and Dynamics, ICASS 2009, Hong Kong, 16-18 December 2009
Vu Van Hung - One of the best experts on this subject based on the ideXlab platform.
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Study of Elastic Moduli of Semiconductors with Defects by the Statistical Moment Method
E-journal of Surface Science and Nanotechnology, 2011Co-Authors: Vu Van Hung, Le Dai Thanh, Ngo Thu HuongAbstract:The elastic moduli of semiconductors at finite temperatures have been studied using the Statistical Moment method. The Young, bulk and shear moduli of the semiconductor with point defects like Si crystal are calculated as a function of the temperature. We discuss the temperature dependence of the elastic moduli of Si crystal with defects and compare the calculated elastic moduli with the experimental results. [DOI: 10.1380/ejssnt.2011.499]
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Investigation of Thermodynamic Quantities of Cubic Zirconia by Statistical Moment Method
2008Co-Authors: Vu Van Hung, Le Dai ThanhAbstract:We have investigated the thermodynamic properties of the cubic zirconia ZrO2 using the Statistical Moment method in the Statistical physics. The free energy, thermal lattice expansion coefficient, specific heats at the constant volume and those at the constant pressure, CV and CP , are derived in closed analytic forms in terms of the power Moments of the atomic displacements. The present analytical formulas including the anharmonic effects of the lattice vibrations give the accurate values of the thermodynamic quantities, which are comparable to those of the ab initio calculations and experimental values. The calculated results are in agreement with experimental findings. The thermodynamic quantities of the cubic zirconia are predicted using two different inter-atomic potential models. The influence of dipole polarization effects on the thermodynamic properties for cubic zirconia have been studied.
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Application of the Statistical Moment method to thermodynamic quantities of silicon
Journal of Physics: Condensed Matter, 2005Co-Authors: Vu Van Hung, Kinichi Masuda-jindo, Pham Thi Minh HanhAbstract:The lattice constants, thermal expansion coefficients, specific heats at constant volume and those at constant pressure, Cv and Cp, second cumulants, and Lindemann ratio are derived analytically for diamond cubic semiconductors, using the Statistical Moment method. The calculated thermodynamic quantities of the Si crystal are in good agreement with the experimental results. We also find the characteristic negative thermal expansion in the Si crystal at low temperatures.
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Thermodynamic quantities of metals investigated by an analytic Statistical Moment method
Physical Review B, 2003Co-Authors: Kinichi Masuda-jindo, Vu Van HungAbstract:The thermodynamic properties of metals are studied by including explicitly the anharmonic effects of the lattice vibrations going beyond the quasiharmonic approximations. The free energy, thermal lattice expansion coefficients, mean-square atomic displacements, and specific heats at the constant volume and those at the constant pressure, C v and C p , are derived in closed analytic forms in terms of the power Moments of the atomic displacements. The analytical formulas give highly accurate values of the thermodynamic quantities, which are comparable to those of the molecular dynamics or Monte Carlo simulations for a wide temperature range. The present formalism is well suited to calculate the thermodynamic quantities of metals and alloys by including the many body electronic effects and by combining it with the first-principles approaches.
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Calculation of thermodynamic quantities of metals and alloys by the Statistical Moment method
Journal of Phase Equilibria, 2001Co-Authors: Vu Van Hung, Kinichi Masuda-jindo, S.r. NishitaniAbstract:The thermodynamic properties of metals and alloys are studied using the Moment method in the Statistical dynamics, which allows us to take into account the anharmonicity of thermal lattice vibrations and size mismatch of constituent atoms, going beyond the quasi-harmonic approximation. Within the fourth-order Moment approximation, the free energy and equilibrium lattice spacing of the binary alloys are given explicitly in terms of the effective pair potentials and the second- and fourth-order vibrational constants. The long-range order (LRO) parameter η and order-disorder transition temperatures (ODTs) Tc of binary alloys are obtained by solving the explicit transcendental equations. The numerical calculations of thermodynamic quantities for Cu3Au and β-CuZn alloys show that the inclusion of the anharmonicity of lattice vibration plays an essentially important role in determining the phase stabilities of metals and alloys.
Jun Zhang - One of the best experts on this subject based on the ideXlab platform.
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Generalization of the Statistical Moment-based damage detection method
Structural Engineering and Mechanics, 2011Co-Authors: Jun Zhang, Yong XiaAbstract:A novel structural damage detection method with a new damage index has been recently proposed by the authors based on the Statistical Moments of dynamic responses of shear building structures subject to white noise ground motion. The Statistical Moment-based damage detection (SMBDD) method is theoretically extended in this paper with general application. The generalized SMBDD method is more versatile and can identify damage locations and damage severities of many types of building structures under various external excitations. In particular, the incomplete measurements can be considered by the proposed method without mode shape expansion or model reduction. Various damage scenarios of two general forms of building structures with incomplete measurements are investigated in consideration of different excitations. The effects of measurement noise are also investigated. The damage locations and damage severities are correctly identified even when a high noise level of 15% and incomplete measurements are considered. The effectiveness and versatility of the generalized SMBDD method are demonstrated.
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Experimental investigation on Statistical Moment-based structural damage detection method
Structural Health Monitoring: An International Journal, 2009Co-Authors: Jun Zhang, Yong XiaAbstract:Although vibration-based structural damage detection methods have demonstrated various degrees of success, the damage detection of civil structures still remains as a challenging task. The main obstacles include the insensitivity to local damage and the high sensitivity to measurement noise. A new structural damage detection method based on the Statistical Moments of dynamic responses of a structure has been recently proposed by the authors, and the numerical study manifested that the proposed method is sensitive to local structural damage but insensitive to measurement noise. The experimental investigation on this method is presented in this article. Three shear building models with and without damage were built and subjected to ground motions generated by a shaking table. The displacement and acceleration responses of each building model at each floor were recorded. The recorded ground motion and building responses as well as identified structural damping ratios were then used to identify damage locatio...
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Statistical Moment-based damage detection of building structures
2009Co-Authors: Jun Zhang, Yong XiaAbstract:4th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2009, Zurich, 22-24 July 2009
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Further development of Statistical Moment-based damage detection method
2009Co-Authors: Jun Zhang, Yong XiaAbstract:6th International Conference on Advances in Steel Structures and Progress in Structural Stability and Dynamics, ICASS 2009, Hong Kong, 16-18 December 2009
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A new Statistical Moment-based structural damage detection method
Structural Engineering and Mechanics, 2008Co-Authors: Jun Zhang, Yong XiaAbstract:This paper presents a novel structural damage detection method with a new damage index based on the Statistical Moments of dynamic responses of a structure under a random excitation. After a brief introduction to Statistical Moment theory, the principle of the new method is put forward in terms of a single-degree-of-freedom (SDOF) system. The sensitivity of Statistical Moment to structural damage is discussed for various types of structural responses and different orders of Statistical Moment. The formulae for Statistical Moment-based damage detection are derived. The effect of measurement noise on damage detection is ascertained. The new damage index and the proposed Statistical Moment-based damage detection method are then extended to multi-degree-of-freedom (MDOF) systems with resort to the leastsquares method. As numerical studies, the proposed method is applied to both single and multi-story shear buildings. Numerical results show that the fourth-order Statistical Moment of story drifts is a more sensitive indicator to structural stiffness reduction than the natural frequencies, the second order Moment of story drift, and the fourth-order Moments of velocity and acceleration responses of the shear building. The fourth-order Statistical Moment of story drifts can be used to accurately identify both location and severity of structural stiffness reduction of the shear building. Furthermore, a significant advantage of the proposed damage detection method lies in that it is insensitive to measurement noise.
