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Analysis of linear elastic fracture mechanics for cracked functionally graded composite plate by enhanced local enriched consecutive-interpolation elements

This paper reports the application of consecutive-interpolation procedure into four-node quadrilateral elements for analysis of two-dimensional cracked solids made of functionally graded composite plate. Compared to standard finite element method, the recent developed consecutiveinterpolation has been shown to possess many desirable features, such as higher accuracy and smooth nodal gradients it still satisfies the Kronecker-delta property and keeps the total number of degrees of freedom unchanged.

5/20/2021 4:43:19 PM +00:00

Ứng dụng mô hình thống kê và mạng nơ-ron lan truyền ngược trong phân tích dự báo chuyển dịch đập thủy điện

Mô hình thống kê hồi quy bội, chuỗi thời gian theo mùa và mạng nơ-ron lan truyền ngược được ứng dụng để phân tích và dự báo chuyển dịch ngang của đập thủy điện Hoà Bình ở giai đoạn vận hành. Dữ liệu thực nghiệm là kết quả quan trắc chuyển dịch ngang, mực nước hồ và nhiệt độ không khí trong 137 chu kỳ quan trắc.

5/20/2021 4:42:46 PM +00:00

One-step synthesis of molybdenum oxide/graphene composites

Herein introduce a new approach to synthesize MoO2/graphene composites via plasma-enhanced electrochemical exfoliation process. Our samples were prepared by electrifying graphite rods in (NH4)2Mo7O24 solution under a DC voltage of 70V. By controlling the experimental parameters such as the initial ratio of [Mo7O24] 2– precursor, the current and time, we can modify the size and the size distribution of MoO2 nanoparticles on graphene sheets. The composites were characterized with Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Diffraction and Raman Spectroscopy.

5/20/2021 4:42:20 PM +00:00

Structure analysis of amorphous and liquid magnesium silicate

Oganov potentials and period boundary condition to perform molecular dynamics simulation of amorphous and liquid Mg2SiO4 systems under pressures 0 GPa and 40 GPa. We clarify structure of amorphous Mg2SiO4 at 0 and 40 GPa and compared with the one of Mg2SiO4 at liquid state. Especially, the origin of sub-peaks in radial distribution function of O-O, Si-Si and Mg-Mg pairs is explained clearly. The change of radial distribution functions, coordination number and the number of all types of bonds including the corner-, edge- and face-sharing bonds is also discussed in detail in this paper.

5/20/2021 4:42:13 PM +00:00

Fabricating ultra-thin silicon nitride membranes suspended on silicon wafer

Ultrathin silicon nitride SiNx membrane suspended on a silicon wafer is a popular twodimensional platform in MEMS applications. The unsupported membrane has a low thermal conductivity, is electrically insulated, and very robust against mechanical impact. Remarkably thin, it is difficult to fabricate and manipulate. Recently equipped with a dual chamber system for plasma enhanced chemical vapor deposition (PECVD) and reactive ion etching, we calibrate it to deposit silicon nitride Si3N4, silicon dioxide SiO2, and to dry etch these materials. Based on the superb quality of Si3N4, we perform a through-wafer etch that creates suspended Si3N4 membranes. The recipe is reliable and reproducible. We analyze the membrane’s chemical composition and optical properties. Although created by PECVD, the membrane is so robust that it survives multiple lithography steps. It extends our capability to study thermal transport at the submicron scale as well as to fabricate micron size devices for MEMS applications.

5/20/2021 4:42:05 PM +00:00

Comparative analysis of reactivity calculations for the CERMET fueled ADS with serpent and MCNP6 codes

The purpose of this study is to verify the accuracy of innovative ADS core modeling by using simulation codes. The reactivity calculations of CERMET loaded fuel ADS was conducted using two Monte Carlo codes, Serpent [8] and MCNP6 [9] with ENDF/B-VII.0 library [10]. The comparison of results obtained from the two codes is analyzed and discussed in this study.

5/20/2021 4:41:32 PM +00:00

On the balance between magnetization and coercivity of MnBi green powders and magnets prepared thereof

The paper considers this problem and discusses how to regulate the processing route to keep this balance to enhance the performance of MnBi green powders and MnBi bulk magnets prepared thereof

5/20/2021 4:41:26 PM +00:00

Mô phỏng trường thủy động lực khu vực cửa Nhật Lệ, Quảng Bình

bài viết tiến hành nghiên cứu khu vực cửa Nhật Lệ (Quảng Bình) nhưng những nghiên cứu này chưa thực sự tập trung vào mô phỏng đặc điểm của trường thủy động lực của khu vực này. Nghiên cứu này sẽ trình bày khả năng ứng dụng mô hình toán để mô phỏng trường thủy động lực cho khu vực cửa Nhật Lệ, Quảng Bình thông qua xây dựng bộ mô hình MIKE 21 dựa trên cơ sở dữ liệu thực đo do Trung tâm Động lực học- Thủy khí- Môi trường thực hiện năm 2018.

5/20/2021 4:41:18 PM +00:00

Structure of GeO2 glass under compression using molecular dynamics simulation

The results show that the Ge-Ge, Ge-O bond distance increase but O-O bond distance decreases when increasing the pressure. We find that the peak splitting of Ge-Ge at high pressure corresponds with the Ge-O-Ge and O-Ge-O bond angles. We also find that O-Ge-O bond angle decreases, and Ge-OGe bond angle increases with pressure. The core-sharing-bond is major at ambient pressure, but fractions of edge and face-sharing-bonds increase with pressure.

5/20/2021 4:41:12 PM +00:00

Theoretical model of guided waves in a bone-mimicking plate coupled with soft-tissue layers

The obtained results and equations discussed in this study could be, in general, useful for further applications in the area of bone quantitative ultrasound.

5/20/2021 4:36:38 PM +00:00

Evaluation of the effect of the concentration of seeding particles on spike-excitation doppler uvp measurement

This study addresses, to some extent, the effect of the seeding-particle concentration on the results of spike-excitation UVP measurements. For the investigation, experimental measurements of water pipe flow have been carefully executed for a wide range of the particle concentration. The dependence of the measured data on the particle concentration is evaluated and reported. The result of this study suggests an appropriate range of the seeding-particle concentration in setting up spike-excitation UVP measurements.

5/20/2021 4:36:30 PM +00:00

Nonlinear vibration of nonlocal strain gradient nanotubes under longitudinal magnetic field

The nonlinear free vibration of embedded nanotubes under longitudinal magnetic field is studied in this paper. The governing equation for the nanotube is formulated by employing Euler–Bernoulli beam model and the nonlocal strain gradient theory. The analytical expression of the nonlinear frequency of the nanotube is obtained by using Galerkin method and the equivalent linearization method with the weighted averaging value. The accuracy of the obtained solution has been verified by comparison with the published solutions and the exact solution.

5/20/2021 4:36:12 PM +00:00

Estimation of heat transfer parameters by using trained pod-rbf and grey wolf optimizer

The search for optimum design variables is conducted by using a recent heuristic method, namely Grey Wolf Optimizer. During the heuristic search, direct heat conduction problem has to be solved several times. The set of heat transfer parameters that lead to smallest error rate between computed temperature field and reference one is the optimum output of the inverse problem. In order to accelerate the process, the model order reduction technique Proper-Orthogonal-Decomposition (POD) is used. The idea is to express the direct solution (temperature field) as a linear combination of orthogonal basis vectors.

5/20/2021 4:35:30 PM +00:00

Amplification of useful vibration using on-off damping

This paper points out how much useful vibration can be extracted from a baseexcited oscillator, which is controlled by the on-off electrical damping. We studies the class of on-off electrical damping controller, which switches the damping level from high to low and back at fixed times every quarter of period. The problem reduces to the maximization of a single-variable function. This result can open the new direction to amplify the useful vibration using controllable dampings.

5/20/2021 4:35:23 PM +00:00

Numerical investigation of force transmission in granular media using discrete element method

In this paper, a numerical Discrete Element Method (DEM) model was calibrated to investigate the transmission of force in granular media. To this aim, DEM simulation was performed for reproducing the behavior of a given granular material under uniform compression. The DEM model was validated by comparing the obtained shear stress/normal stress ratio with results published in the available literature. The network of contact forces was then computed, showing the arrangement of the material microstructure under applied loading...

5/20/2021 4:34:45 PM +00:00

Large displacements of FGSW beams in thermal environment using a finite element formulation

In the present work, the large displacement behaviour of FGSW beams in thermal environment is studied by a finite element formulation. The beams considered herein consist of three layers, a homogeneous core and two FGM skin layers. The material properties are assumed to be temperature dependent, and they are graded in the thickness direction by a power gradation law. Based on Antman beam model, a nonlinear beam element using linear interpolation is formulated in the context of the total Lagrange formulation. In order to avoid the shear locking, reduced integration technique is employed to evaluate the strain energy. Numerical investigations are carried to show the accuracy of the formulated element and highlight the influence of the material inhomogeneity, temperature rise and layer thickness ratio on the large displacement behaviour of the beams.

5/20/2021 4:34:24 PM +00:00

Free vibration of FG sandwich plates partially supported by elastic foundation using a quasi-3D finite element formulation

The quasi-3D shear deformation theory, which takes the thickness stretching effect into account, is adopted to formulate a finite element formulation for computing vibration characteristics. The accuracy of the derived formulation is confirmed through a comparison study. The numerical result reveals that the foundation supporting area plays an important role on the vibration behavior of the plates, and the effect of the layer thickness ratio on the frequencies is governed by the supporting area. A parametric study is carried out to highlight the effects of material distribution, layer thickness ratio, foundation stiffness and area of the foundation support on the frequencies and mode shapes of the plates. The influence of the side-to-thickness ratio on the frequencies of the plates is also examined and discussed.

5/20/2021 4:34:14 PM +00:00

A comprehensive review on dual approach to the vibration analysis: Some dual techniques and application

This paper reviews key ideas of the researches on the dual approach to the vibration analysis. Three types of dual techniques, namely, forward - return dual technique, global-local dual technique, weighted averaging dual technique, for the problem of equivalent replacement are summarized.

5/20/2021 4:34:07 PM +00:00

Experiments and optimization for the wedm process: A trade-off analysis between surface quality and production rate

This work addressed a parameter optimization to simultaneously decrease the root mean square roughness (Rq) as well as the thickness of the white layer (TW) and improve the material removal rate (MRR) for the wire electro-discharge machining (WEDM) of a stainless steel 304 (SS304). The factors considered are the discharge current (C), the gap voltage (VO), the pulse on time (POT), and the wire drum speed (SP). The interpolative radius basic function (RBF) is applied to show the correlation between the varied factors and WEDM performances measured.

5/20/2021 4:33:55 PM +00:00

Theoretical and experimental analysis of the exact receptance function of a clamped-clamped beam with concentrated masses

This paper establishes the exact receptance function of a clamped-clamped beam carrying concentrated masses. The derivation of exact receptance and the numerical simulations are provided. The proposed receptance function can be used as a convenient tool for predicting the dynamic response at arbitrary point of the beam acted by a harmonic force applied at arbitrary point.

5/20/2021 4:33:43 PM +00:00

Dynamic responses of an inclined FGSW beam traveled by a moving mass based on a moving mass element theory

The element using hierarchical functions to interpolate the displacements and rotation is efficient, and it is capable to give accurate dynamic responses by small number of the elements. The effects of the moving mass parameters, material distribution, layer thickness ratio and inclined angle on the dynamic behavior of the FGSW beam are examined and highlighted.

5/20/2021 4:33:05 PM +00:00

Homogenization of very rough three-dimensional interfaces for the poroelasticity theory with biot’s model

n this paper, we carry out the homogenization of a very rough threedimensional interface separating two dissimilar generally anisotropic poroelastic solids modeled by the Biot theory. The very rough interface is assumed to be a cylindrical surface that rapidly oscillates between two parallel planes, and the motion is time-harmonic. Using the homogenization method with the matrix formulation of the poroelasicity theory, the explicit homogenized equations have been derived.

5/20/2021 4:32:59 PM +00:00

Determining of the laser heat flux for three-dimensional conduction model by the sequential method

In this study, the Newton–Raphson method has been calibrated as an operational algorithm to evaluate the laser heat flux value accurately in the 3-D conduction model. To confirm the effectiveness of the presented method, the paper has given two specific applications. It is obtained that the sequential method is a reasonable, correct, and powerful method to determine the inversely laser heat flux in the three-dimensional conduction model.

5/20/2021 4:32:52 PM +00:00

Effective medium approximation for conductivity of coated-inclusion composites with anisotropic coating

Effective medium approximations are constructed in this paper to estimate the macroscopic conductivity of coated-inclusion composites with thin anisotropic coating. The two-phase coated-inclusion are substituted by equivalent one-phase inclusion, using the multi-coated spheres assemblage and the differential substitution approaches. Then, the usual effective medium approximation schemes are applied to the equivalent medium to estimate the conductivity of original three-phase composites. The results obtained were compared with the numerical simulation by finite element method in 2D show the effectiveness of the methods.

5/20/2021 4:32:35 PM +00:00

Lower bound of performance index of anti-sway control of a pendulum using on-off damping radial spring-damper

This paper studies the class of on-off damping controller, which switches the damping level from high to low and back at fixed times every quarter of period. Among this class, this paper shows the solution of the lower bound controller producing the lowest amplitude-frequency curve. The lower bound curve shows some fundamental natures of the system and gives some useful directions for a good on-off damping controller.

5/20/2021 4:32:15 PM +00:00

Effect of viscosity on slip boundary conditions in rarefied gas flows

In this paper we investigate the effect of the gas viscosity on the surface properties as surface gas temperature and slip velocity in rarefied gas simulations. Three various viscosity models in the literature such as the Maxwell, Power Law and Sutherland models are evaluated. They are implemented into OpenFOAM to work with the solver “rhoCentralFoam” that solves the Navier-Stokes-Fourier equations.

5/20/2021 4:32:04 PM +00:00

Nonlinear dynamic buckling of full-filled fluid sandwich FGM circular cylinder shells

This paper is concerned with the nonlinear dynamic buckling of sandwich functionally graded circular cylinder shells filled with fluid. Governing equations are derived using the classical shell theory and the geometrical nonlinearity in von Karman–Donnell sense is taken into account. Solutions of the problem are established by using Galerkin’s method and Runge–Kutta method. Effects of thermal environment, geometric parameters, volume fraction index k and fluid on dynamic critical loads of shells are investigated.

5/20/2021 4:31:48 PM +00:00

Estimates for the elastic moduli of 2D aggregate of hexagonal-shape orthorhombic crystals with in-plane random crystalline orientations

Numerical finite element simulations on the homogenization problem for large samples of particular 2D hexagonal-shape-geometry random orientation aggregates from the base crystals of orthorhombic symmetry have been performed. At sufficiently large random-aggregate samples, the scatter intervals of the macroscopic 2D bulk and shear elastic moduli converge toward the Voigt-Reuss-Hill bounds, and then our recently constructed theoretical estimates, which have been specified for the aggregates.

5/20/2021 4:31:41 PM +00:00

Resonant and antiresonant frequencies of multiple cracked bar

The present paper addresses analysis of antiresonant frequencies of multiple cracked bar in comparison with the resonant ones. First, exact characteristic equations for the resonant and antiresonant frequencies of bar with arbitrary number of cracks are conducted in a new form that is explicitly expressed in term of crack severities. Then, the conducted equations are employed for analysis of variation of resonant and antiresonant frequencies versus crack position and depth. Numerical results show that antiresonant frequencies are indeed useful indicators for crack detection in bar mutually with the resonant ones.

5/20/2021 4:31:27 PM +00:00

Vibration under variable magnitude moving distributed masses of non-uniform bernoulli–euler beam resting on pasternak elastic foundation

The dynamic response to variable magnitude moving distributed masses of simply supported non-uniform Bernoulli–Euler beam resting on Pasternak elastic foundation is investigated in this paper. The problem is governed by fourth order partial differential equation with variable and singular coefficients. The main objective of this work is to obtain closed form solution to this class of dynamical problem. In order to obtain the solution, a technique based on the method of Galerkin with the series representation of Heaviside function is first used to reduce the equation to second order ordinary differential equations with variable coefficients.

5/20/2021 4:30:35 PM +00:00