bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal variation of residual flow in the east sea
Authors: Manh Dinh Van , Yanagi Tetsuo
Published: April 2018

A diagnostic three-dimensional numerical model has been established in order to reveal the seasonal variation of residual flow, including wind-driven current, density-driven current and tide-induced residual current, in the East Sea. The observed data on water temperature, salinity (from JODC, 1930-1996) and wind (from GOADS, 1961-1991) were exploited in this study. Residual flows in 4 seasons (spring, summer, autumn and winter) were simulated. Furthermore, the contribution of each component, wind-driven, density-driven and tide-induced residual current, was evaluated. On the basis of the obtained results, it is shown that the wind-driven current plays an important role in the basin-wide circulation in the East Sea, especially in the surface layer. At the lower levels, the density-driven current becomes more significant. The tide-induced residual current is relatively small.
Numerical solution for consistent initial conditions of constrained mechanical systems
Authors: Phong Dinh Van
Published: April 2018

The article deals with the problem of consistent initial values of the system of equations of motion which has the form of the system of differential-algebraic equations. Direct treating the equations of mechanical systems with particular properties enables to study the system of DAE in a more flexible approach. Algorithms and examples are shown in order to illustrate the considered technique.
Lateral turbulent mixing forces in the long shore current calculation by Longuet-Higgins method and their influence on long shore sediment transport
Authors: Hung Nguyen Manh
Published: April 2018

Longuet - Higgins method for long shore current and Bijker method for sediment transport calculations are worldwide used mathematical model in the coastal engineering. When using them, we should image how work the methods and what is sensitivity and influence of each parameters on final results as sediment transport. In this paper, the influences of parameters N, P of lateral turbulent mixing forces on the long shore current and then on the sediment transport are estimated. The Bijker example is used and the computation results are compared with Bijker results for neglecting the lateral turbulent mixing. A field application with appropriate parameters N and P for Le Thuy beach is obtained for verification of long shore current and sediment transport.
The balancing of rotating machinery as non-linear system passing across a resonant region
Authors: Menh Nguyen Cao , Tri Tran Duong
Published: April 2018

This paper presents a dynamical balancing method for the rotational part of machine as a nonlinear system with the decrease of rotation speed passing across a resonant region. After analyzing the nonlinear system and measurable vibration signals, a suitable procedure of dynamical balance for determining the magnitude and location of imbalance mass is proposed. A program on PC is made to illustrate the obtained procedure. The results of numeric examples show that it can be used well for dynamical balancing analysis.
A new method for determination of the reliability index of distributed parameter systems
Authors: Pho Nguyen Van
Published: April 2018

In this paper, a method to determine the reliability - index of distributed systems is proposed. By the new method, instead of finding jointly probability depending on multi - conditions of inequalities one can find probability depending on only one inequality and no requiring to know jointly density function of basic variables. Therefore, it is very favourable for the calculation of the reliability - index of mechanical systems with distributed parameter. For illustrating the proposed method, a simple example is considered
On the observable conditions in the nonlinear systems
Authors: Bang Nguyen Thanh
Published: April 2018

None
Vấn đề khảo sát phương trình Fokker-Planck-Kolmogov bằng phương pháp tham số điều khiển
Authors: Anh Nguyen Dong
Published: April 2018

None
Vấn đề khảo sát phương trình Fokker-Planck-Kolmogov bằng phương pháp khai triển chuỗi Macloren theo tọa độ ẩn
Authors: Anh Nguyen Dong
Published: April 2018

None
The oscillations of the dynamical system with hysteresis characteristics excited by stochastic parameter and forces. I.
Authors: Menh Nguyen Cao
Published: April 2018

In this paper, the nonlinear mechanical system with imperfect elastic characteristics excited by parameter and external forces in the form of stationary Gaussian stochastic processes is considered. Heuristic and enveloped methods in a similar way as in the paper [5] are used. The closed differential equation system with constant coefficients is established to determine the statistical characteristics of solution process.
On the justification of Gaussian heuristic method in the theory of random vibration
Authors: Menh Nguyen Cao
Published: April 2018

Recently in the problems of random vibration, the heuristic method, in which output process is supposed to be Gaussian when Gaussian input process is given, is applied [1, 2]. This method is called the “Gaussian heuristic method”. This paper deals with the justification of “Gaussian heuristic method”, form that two following important conclusions are proved: - “Gaussian heuristic method” gives density function of probability with the first order approximation with respect to the small parameter ε. - Applying this method we get mean values and second order correlation functions in second order approximation with respect to the small parameter ε.
The tuned-absorber in self-excited system
Authors: Dinh Nguyen Van
Published: April 2018

In this paper the self-excited system with tuned absorber is examined. Two kinds of absorbers have been considered: the non-resonant absorber and the resonant one. For the first kind, the self-excitation can be fully suppressed by increasing the damping coefficient: While for the second one, that may be only by making a rational choice of this coefficient. In the case of system with several degrees of freedom, the resonant absorber with several degrees of freedom can be used.
The theory on homogeneous micro-fluid mixtures
Authors: Diep Nguyen Van , Chanh Truong Minh
Published: April 2018

This paper deals with the construction x of a generalized- diffusive theory of simple micro-fluid mixtures composed of a reactive constituents in the relative motion to one another and treated as a single simple micro-fluid. The basic laws of balance are given by postulating the balance law of energy together with invariant requirement under superposed rigid body motions or the mixture as a whole. The linear or nonlinear constitutive equations and full thermodynamic restrictions are given.
Phương pháp truyền nhảy nút mô men không cân bằng áp dụng cho hệ khung phẳng liên tục
Authors: Cau Vu Nhu
Published: April 2018

None
Cơ sở phương pháp tiệm cận trong hệ phi tuyến mạnh có chậm
Authors: Lan Nguyen Khac
Published: April 2018

None
Một cách tính kết cấu nhịp cầu giàn chịu tải trọng thẳng đứng có kể đến sự làm việc của hệ liên kết ngang
Authors: Khai Nguyen Nhu , Trinh Leu Tho
Published: April 2018

None
The theoretical model of interaction between the baroclinic boundary layers of atmosphere and ocean
Authors: Ly Le Ngoc
Published: April 2018

Presenting the theoretical model of the atmospheric and oceanic baroclinic boundary layers by interaction.Baroclinic effects of two boundary layers are described by the horizontal gradients of air temperature and water density in the equations of motion.The formulas computing the characteristics of the oceanic atmospheric baroclinic boundary layers were obtained.The above 1heoretical model is the general case of the model interaction of barotropic boundary layers.
The oscillations of the dynamical systems with hysteresis characteristics excited stochastic parameter and forces. II
Authors: Menh Nguyen Cao
Published: April 2018

In this paper, the problem in [1] is continued studying. The some special cases of the general problem are considered. The beam with internal friction under stochastic forces is analyzed. In this example the influence of the hysteresis character in material and the parameter in the system on the oscillations of the beam are shown.
Problem of optimization of statically indeterminate structures for moving loads
Authors: Son Do
Published: April 2018

In this paper formulated a problem of optimization of statically indeterminate structures for moving loads in the shake-down state by a linear programming using the simplex method. The algorithm and numerical results have been illustrated by the computation of a statically indeterminate beam.
Sediment distribution in turbulent flow
Authors: Dac Nguyen Tat , Son Pham
Published: April 2018

Using the classical diffusive equation with variable coefficient of diffusion the authors solve a problem concerning with sediment distribution in turbulent flow having construction. The sediment concentration distribution is pointed out in the paper.
Cơ học với vũ trụ
Authors: Chi Nguyen Huu
Published: April 2018

None
Phương pháp tính độ lún động của móng trên nền đàn hồi có dư khi dao động tự do
Authors: Bang Vu Van
Published: April 2018

None
Tình hình và triển vọng nghiên cứu ứng dụng kết cấu xi măng lưới thép trong giao thông vận tải và xây dựng ở nước ta
Authors: Son Do
Published: April 2018

None
On the elastoplastic stability of a plate under shear forces, taking into account its real bending form
Authors: Bich Dao Huy
Published: April 2018

Using the theory of elastoplastic processes and the modified elastic solution method we investigate the stability outside elastic limit problem of a plate under shear forces, taking into account its real bending form after the loss of stability. An expression for determining the critical force is obtained and numerical calculations with various ratio of thickness have been fulfilled, from the results one can see the convergence of the modified elastic solution method.
Solving method for stability problem of elasto plastic cylindrical shells with compressible material subjected to complex loading processes
Authors: Dung Dao Van
Published: April 2018

The system of stability equations of elasto plastic cylindrical shell made of compressible material was established in work [3]. In the present paper, we study the solution of the problems and methods for determining the critical load. The obtained results describe the influence of the compressibility of material on the stability of the shell. When a material is incompressible, these results red.uce to the previous well-known ones (see [1, 2, 4, 5]).
Approximate analysis of some two-degree-of-freedom nonlinear random systems by an extension of Gaussian equivalent linearization
Authors: Hung Luu Xuan
Published: April 2018

The paper presents the analysis of some two-degree-of-freedom nonlinear systems under random excitation using Local Mean Square Error Criterion which is an extension of Gaussian Equivalent Linearization. The results obtained shows that the new technique can be very efficiently used not only for simple-degree-of-freedom systems as presented in the previous papers, but also for multi-degree-of-freedom ones. The solution accuracy obtained by the proposed technique is much more improved than that using the traditional linearization. The conclusions in the paper point up the significance of this technique.
3-D numerical simulation of the tidal circulation in the Gulf of Tonkin, Vietnam
Authors: Vinh Phan Ngoc , Dan Nguyen Kim
Published: April 2018

The purpose of this paper is to present 3-D numerical simulation of the tidal circulation in the Gulf of Tonkin. A sigma-coordinate system transformation is used to make possible a total fitting between the computing point-grid and the bottom topography as well as the free water surface. A turbulence-closure sub-model K-L which permits the parameterization of the turbulence mixing is also included. The studied domain, the whole Gulf of Tonkin, extends from the coastal zone of Quang-Ninh into Thua Thien Hue province and as far as Hai-Nam (China) island seawards. The model have been calibrated and verified by the observed data at six different stations for a three and seven-day periods. The results are in good agreement with the observed data. The kinetic energy distribution was considered.
Two-dimensional optimization problem of plant location
Authors: Linh Tran Gia , Vinh Phan Ngoc
Published: April 2018

In this paper, the following matters are presented: the adjoint problem of the two-dimensional matter propagation problem; the algorithm for determination of a domain in which a plant can be located so that the values of the pollution-level reflecting functional does not exceed a given value at considered sensitive areas; application of this algorithm for numerical experiments to a typical problem.
Generalized diffusion theory of non-rotational, rigid spherical particle sedimentation in viscous fluid
Authors: Phan Nguyen Hong , Diep Nguyen Van
Published: April 2018

This paper is devoted to application of Generalized Diffusion Theory for solving a sedimentation problem of rigid spherical particles in viscous fluid. The governing equations have been obtained. It is shown that, in this case the governing equation system is a hyperbolic one, and the equations in the characteristic form have been derived. The mathematical properties of the obtained equation system and the solution for stationary sedimentation where investigated numerically.
A variable separation method for the calculation of the reliability of construction
Authors: Pho Nguyen Van
Published: April 2018

In this paper, a variable separation method for determining the reliability of construction is proposed. Therefore, the reliability is a multiplication of two probabilities: The probability of the occurrence of load and the probability of construction in the condition the load has a determined value.
Hygroscopically induced residual stresses in composite laminates
Authors: Thinh Tran Ich , Khoa Ngo Nhu
Published: April 2018

In this paper the exact moisture concentration function m(z, t) is used to compute the hygroscopic residual stresses in laminated composites. The governing equations were established by using a full higher-order displacement theory. Hygroscopically induced residual stresses in thick graphite-epoxy composite laminates: Cross-ply [0/90] 8 based on this approach were compared with those obtained by assumption: the moisture concentration m is a constant in all plies through the laminates thickness
Reliability - safety set of structures
Authors: Huynh Le Xuan , Binh Do Van
Published: April 2018

Based on the results of A. D. Rzanitsin and V. D. Raizer in the references of [1] and [2], this paper gives other definitions of the confidence level of subjected loads βs and the confidence level of the strength of materials βR, then studies the relationship between the load factor k, the material factor m and the safety factor n in the traditional models with the factors of βs, βR and βs in the random models in the structural design. The research results show that physical meaning of two factors of βs, βR is the same as the factors of k and m, however it gives more clearly assessments on effects of the over load state and the material inhomogeneous state of the safety working state of the structures. Since the reliability - safety set is also determined from the research results. Some numerical examples are carried out to show the relationship between these above factors.
Static diagnosis of multiple cracked beam
Authors: Lien Tran Van
Published: April 2018

None
Stability analysis of cylindrical shells subjected to complex loads
Authors: Nhu Ngo Huong
Published: April 2018

The paper deals with stability analysis of shell on the basis FEM via Castem 2000. The numerical results of stability problems of cylinders subjected to different loads as compress load, pressure, concentrated and combined loads are compared with analytical result and give a good agreement. The influence of changing radius of the cylindrical shell on the unstable forms and the influence of angles of fibers on unstable behaviour of laminated composite shell are considered. Numerical results and corresponding programs by languages Gibian given in the paper to realize software Castem 2000 can be applied in the design and in the stability analysis of the shell with more complex conditions
An approximate method for analysing non-linear systems subject to random excitation
Authors: Anh Nguyen Dong , Hai Ninh Quang
Published: April 2018

A solution technique based on the representation of the response of the non-linear system by a polynomial of the response of the linearized system is presented. The relation between the original non-linear system and the linearized system is introduced by considering the so-called extended moment equations and their closed set is to be solved to determine unknowns. For the Vanderpol oscillator subject to white noise excitation, the technique gives good approximation to the response moments as well as the probability density function.
A non-linear element for analysing elastic frame structures at large deflections
Authors: Kien Nguyen Dinh
Published: April 2018

A non-linear finite element for analyzing elastic frame structures at large deflections is presented. A co-rotational technique combined with Classical beam theory with the inclusion of the effect of axial forces is adopted. The element nodal force vector is derived from the strain energy of the element. The element tangent stiffness matrix is obtained by differentiating the nodal force vector, with respect to the degree of freedom (d.o.f.). The obtained formulations have a simple and compact mathematical forms which are easy to implement into a computer program. An incremental interactive technique based on Newton-Raphson method is adopted to solve the non-linear equation and to trace the equilibrium paths of the structures. Numerical examples are presented to show the accuracy and efficiency of the proposed formulations.
NUMERICAL AND EXPERIMENTAL MODELING OF INTERACTION BETWEEN A TURBULENT JET FLOW AND AN INLET
Authors: Lien H. D. , Antonov I. S.
Published: April 2018

In ventilation devices to get rid of harmful substances out of workingplaces, we use sucking devices. The local sources of pollution are evacuated by them. Abasic element when creating the model of sucking device is: the source of harmful substancesis discussed as a rising convective flow, which is ejected out of sucking spectrum,created by a sucking apparatus. In the present work, the flow is a whole one with variablequantity of motion and kinetic energy along it's length. The change in those twoparameters is caused by and is in dependent function of the inlet spectrum. There hasbeen discussed a two-component flow of air and gas in ventilation devices. A two-velocityscheme of flow is used to realise the numerical method. An integral method of investigationis used, based on the conditions of conservation of mass contents, quantity of motion andkinetic energy. It's been accepted that quantity of motion and energy change in functionof inlet action. A comparison of numerical results and natural experiment are made fortwo conditions: full suck and not full suck. Conclusion is that the present model is preciseand can be unset for engineering calculations.
Simulation and computation of oscillation and stability of hammer-pontoon systems
Authors: Menh Nguyen Cao , Dac Nguyen Van , Khiem Vu Tan , Nga Hoang
Published: April 2018

Hammer pontoon systems are usually used for pile-driving of onshore construction. The systems are constantly acted upon by marine wave, wind and current and have to be fixed by moorings. In this paper, on the basis of software ALASKA the system is simulated as dynamics of multi-body systems. Its natural frequencies and mode shapes are computed in order to avoid resonant phenomena by the change of design parameters. The vibration displacement at any point of the system is calculated for estimation of technical stability of the system. The reaction forces at joints between bodies and its inertial forces are obtained for calculation of system strength of material. The ambient exciting loads are regarded as deterministic forces and as stochastic ones. In the latter case, the load is given as spectral density function and it is necessary to calculate probability characteristics of system responses. An example is investigated for illustration.
A form of equation of motion for Chaplyghin's systems
Authors: Sanh Do
Published: April 2018

None
A mixed problem of active aerosol pollution
Authors: Dung Hoang Dinh
Published: April 2018

The mixed problem of active aerosol pollution is stated in the mathematical modeling of environment problems [1] and was studied by some authors (see [1], [2], [3], ...). In this work we give the solution using the theory of Schwartz distributions.
The interaction between two parametric excitations of the second and third degrees
Authors: Dao Nguyen Van
Published: April 2018

The interaction between nonlinear oscillations is an interesting problem which has attracted many researches. The interaction between forced and parametric excitations and between two parametric excitations of first and second degrees and first and third degrees, is informed in [1]. In the present paper, we study interaction between two parametric excitations of the second and third degrees. The asymptotic method of nonlinear mechanics in combination with a computer is used.
Linearization of randomly excited nonlinear systems by using local mean square error criterion
Authors: Hung Luu Xuan
Published: April 2018

The paper presents the analysis of three non-linear systems under random excitation by using Local Mean Square Error Criterion which is an extension of Gaussian Equivalent Linearization proposed by Caughey. The obtained results shows that the new technique allows to get much more accurate solutions than .that using Caughey Criterion. The paper leads out some new conclusions which have not been found yet by the previous researches. The new conclusions more clarify the significance of this technique.
Modified elastic solution method in solving elastoplastic problems of structure components subjected to complex loading
Authors: Bich Dao Huy
Published: April 2018

Modified elastic solution method in the elastoplastic process theory has been proposed by the author [2] and was applied in solving some 2D and 3D elastoplastic problems of structure components subjected to complex loading. The method makes use of an algorithm in which a step is made in the loading process and iterations are carried out on this step. The performance of the method was fulfilled and the convergence of the method was considered numerically. In this paper the other performance of this method is presented and the convergence of the method is proven theoretically in the general case of a hardening body which obeys the elastoplastic process theory. The more complicated 3D problem of bodies of revolution subjected to non-axially symmetric load is investigated.
Mixed regime in a quasi-linear system
Authors: Dinh Nguyen Van , Chi Tran Kim
Published: April 2018

A quasi-linear system with cubic nonlinearity under two external excitations in sub harmonic responses of order 1/2 and 1/3 was examined. In the system under consideration there appears mixed oscillation due to the interaction between derived excitations. Various forms of the resonance curve were identified. The stability study was based on an abbreviated form of the second stability condition [2].
On a programme for the balancing calculation of flexible rotors with the influence coefficient method
Authors: Khang Nguyen Van , Luong Tran Van
Published: April 2018

This paper presents the influence coefficient method of determining the locations of unbalances on a flexible rotor system and the correction weights. A computer software for calculating the at-the-site balancing of a flexible rotor system was created using C++ language at the Hanoi University of Technology. This software can be used by balancing flexible rotors in Vietnam.
Reliability index of distributed parameter system
Authors: Pho Nguyen Van
Published: April 2018

In this paper, a method to determine the reliability index of distributed parameter systems by using a method of approximation the multi-condition dependent probability by a one-condition dependent probability is proposed. Therefore, the problem of the reliability index of distributed parameter system is transformed into the defined case. To illustrate for the method, the reliability index of air tube is considered.
A METHOD FOR TECHNICAL DIAGNOSIS OF CONSTRUCTION
Authors: Pho Nguyen Van
Published: April 2018

None
An algorithm for deriving equations of motion of constrained mechanical system
Authors: Phong Dinh Van
Published: April 2018

The article deals with the form of equations of motion of mechanical system with constraints. For holozoic systems the number of differential equation is equal to the degrees of freedom, without regard to the number of chosen coordinates. The possibilities of computer processing (symbolical and numerical) are shown. Two simple examples demonstrate the described technique.
The influence of second order narrow-band colored noises on non-linear random vibrations
Authors: Anh Nguyen Dong , Tinh Nguyen Duc
Published: April 2018

Since the effect of some nonlinear terms is lost during the first order averaging procedure, the higher order stochastic averaging method is developed to predict approximately the response of linear and lightly nonlinear systems subject to weakly external excitation of second order colored noise random processes. Application to Duffing oscillator is considered.
Nonlinear oscillators under delay control
Authors: Dao Nguyen Van
Published: April 2018

In this paper, oscillations and stability of nonlinear oscillators with time delay are studied by means of the asymptotic method of nonlinear mechanics. Harmonic, super harmonic, subharmonic and parametric resonances of a Duffing's oscillator are analyzed. Analytical method in combination with a computer is used.
Calculation of the goffered multilayered composite cylindrical shells by using the finite element method
Authors: Toan Pham Thi
Published: April 2018

In the present paper, the goffered multilayered composite cylindrical shells is directly calculated by finite element method. Numerical results on displacements, internal forces and moments are obtained for various kinds of external loads and different boundary conditions.
Quantization Structure of Orbital Oscillators and Mass Spectrum of Bosonic String
Authors: Duc Dao Vong , Hang Phuong Thi Thuy
Published: April 2018

We consider a mechanism for removing tachyon field in bosonic string based on some modification of the structure of the commutation relations between coordinate orbital oscillators. This change causes the shifting of the mass spectrum for the component fields of the string field functional.
Influence of Mn2+ Concentration and UV Irradiation Time on the Luminescence Properties of Mn-doped ZnS Nanocrystals
Authors: Thi Tran Minh
Published: April 2018

ZnS:Mn were prepared by wet chemical method with Mn doping concentration from 0 at% to 12 at%. The structure and particle size of the obtained powders were measured by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and shown that all samples are single phase with sphalerite crystal structure and average particle size of about 5 - 7 nm. The dependence of Mn2+ ions doped concentration, and UV irradiation time on the luminescent intensity of ZnS:Mn nanocrystals was discussed.
Investigating the Effect of Matrices and Densities on the Efficiency of HPGe Gamma Spectroscopy Using MCNP
Authors: Loan Truong Thi Hong , Phuong Dang Nguyen , Phong Do Pham Huu , Khanh Tran Ai
Published: April 2018

When determining radioactivities in environmental samples using low-level gamma spectroscopy, in order to raise detection limit, voluminous samples are used. It takes in account for the self-absorption (self-attenuation) of gamma rays in samples. The self-absorption effect is small or large depend on the sample shapes, matrices and densities. In this paper, we investigated the effect of some regular matrices such as water, soil, epoxy resin on the detector efficiency. Some analytical formulas for the correction of matrix and densities for soil sample was established and applied to calculate some activities from standard sample of IAEA-375.
Electromagnetic Superpotentials forthe Liénard - Wiechert Field
Authors: Barrera F. V. , López-Bonilla J. , Sosa P. J.
Published: April 2018

Weert deduced a superpotential for the bounded part of the Maxwell tensor \(T_{ab}\) $ associated to the Liénard-Wiechert field. In this work we explicitly construct the non-local superpotential for the radiative part of \(T_{ab}\).
Influence of the Frequency-chirp Gaussian Pulse on the Pulse Broadening in %the Dispersive Fibers
Authors: Kien Bui Xuan , Hung Tran Hai , Chien Trinh Dinh
Published: April 2018

A signal optical pulse propagating in the fiber is affected by many factors, one of the most important among them is dispersion. Under the dispersive influence, the optical pulse is reshaped, particulally, its duration is changed. Especially, the pulse duration change of the optical short pulse with the frequency-chirp is unregular. It influences to the propagating distance in the fiber optic network.In this paper, the expression of the signal optical pulse with the frequency-chirp propagated through the dispersive fiber is derived. This expression described the broadening of the pulse in propagating process (broadening factor), which depends on the frequence chirp and dispersive parameters. The influence of those parameters on the pulse broadening is simulated and discussed.
Table of Contents
Authors: - - -
Published: April 2018

Table of Contents, Vol. 23, No. 4 (2013)
Influence of Spray Rate on Structural and Optical Properties of Sprayed ZnO Films
Authors: Thai Tran Thanh
Published: April 2018

In this report, the ZnO nanostructure films have been deposited by ultrasonic spray pyrolysis technique (USP) on fluorine doped tinoxide~(FTO) substrate using zinc acetate and aqueous 2-propanol as reactants. The effects of solution spray rate on structural, morphological and optical properties of ZnO nanostructure films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and UV-Vis measurements. ZnO films were crystallized in the hexagonal wurtzite phase and preferential orientation changed with changing of spray rate. Grain size and roughness of films depended on spray rate. Increasing spray rate made the films grown with bigger grain size and higher roughness. Band gap energy was determined from the UV-Vis. Its value was found to be of 3.25 eV and was almost independent on the spray rate.
Stopping Powers of Alpha Particles in Some Gases At Energies From 1.0 to 6 MeV
Authors: Khiem Le Hong , Trong Tran Dinh , Nghia Nguyen The
Published: April 2018

Stopping powers of \(\alpha\)-particles emitted by \(^{148}\)Gd, \(^{241}\)Am and \(^{243}\)Cm isotopes in PR10 and isobutane (C\(_{4}\)H\(_{10}\)+Ar) gases have been experimentally measured in the energy region from 1.0 to 5.5 MeV. The experimental data were compared with those calculated by SRIM-2013 computer code. It was concluded that the experimental stopping powers in our investigated region are in agreement with the calculated values.
Ultrasonic-Controled Microlens Arrays in Germanium for Optical Tweezers
Authors: Quy Ho Quang , Thinh Nguyen Van , Lanh Chu Van
Published: April 2018

The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is theoretically proposed. The simulated results show the proposed microlens arrays can be used for optical tweezers arrays to trap an assembly micro-beads. Moreover, with the control by changing of the ultrasonic intensity and frequency, the optical tweezers arrays will act as the dynamical one, which can sieve the beads in (X,Y) plane in the embedding fluid.
Assessment of Radioactive Gaseous Effluent Released From Nuclear Power Plant Ninh Thuan 1 under Scenario of Ines-Level 5 Nuclear Accident
Authors: Khai Nguyen Tuan , Cuong Le Dinh , Anh Do Xuan , Thang Duong Duc , Giap Trinh Van , Ha Nguyen Thi Thu , Bac Vuong Thu , Quang Nguyen Hao
Published: April 2018

Based on guides RG 1.109, RG 1.111 published by United States Nuclear Regulatory Commission (USNRC)~our~research~concentrates on assessing radiation doses caused by radioactive substances released from the nuclear power plant (NPP) Ninh Thuan 1 to the environment under scenario of an INES-level 5 nuclear accident caused by two incidents of the station black out (SBO) and loss of coolant accident (LOCA) using software~RASCAL4.3~provided by the Emergency Operations Center of USNRC. The plant Ninh Thuan 1 is assumed to use the VVER-1200 technology with a total power of 2400 MW\(_{e}\). The input data for the model calculations is based on building the accident scenario, the technical parameters of VVER-1200 technology and the meteorology. The meteorological data on dry and rainy seasons, which are typical for the Ninh Thuan region was also considered. The \(X/Q\) (s/m\(^{3}\)) quality and the maximum dose values were calculated within an area of 40 km radius from the NPP site, where \(X/Q\) (s/m\(^{3}\)) is the ratio of activity concentration to release rate. Based on the obtained results on dose distribution the necessary measures for nuclear emergency preparedness have been proposed according to the IAEA recommendations.
ERRATUM: Simulation for Neutron Transport in PWR Reactor Moderator and Evaluation for Proper Thickness of Light Water Reflector
Authors: - -
Published: April 2018

ERRATUM: Simulation for Neutron Transport in PWR Reactor Moderator and Evaluation for Proper Thickness of Light Water Reflector[Nguyen Tuan Khai and Phan Quoc Vuong, Comm. Phys. 25(1) (2015) 91--96]
Research of Soil Moisture Retrieval Algorithms for Processing Radiometry Data
Authors: Anh Vo Thi Lan , Chung Doan Minh , Ngoc Ngo Tuan , Kostov K. G.
Published: April 2018

Since 2012, the experts of Space Technology Institute  have carried out the field experiments to obtain a high-resolution dataset  of microwave radiometers for land surface parameters (soil moisture, soil  temperature, vegetation water content), in order to improve the soil  moisture retrieval methodology. L-band radiometers were used for measuring  the brightness temperature of the bare soil. Field experiments for passive  microwave remote sensing of soil moisture were carried out in Hoai Duc  District in 2012. L-band microwave radiometers were used for measuring the  microwave emission of bare agricultural fields. The radiometers, which are  used for soil moisture measurement, worked well during the experimental  campaign and produced volumetric soil moisture estimates that compared well  with the ground-truth measurements. Explanations for the observed  discrepancies are presented. The experimental results showed that the model  of Choudhury et al. for surface roughness correction provides a better fit  to radiometric data over the angular range between 20° and 50° for  \(n = 0\) (i.e., the \(\cos ^{2}\theta\)  factor in the exponential in (15) is suppressed).  Based on the results of the experiments conducted over two experimental  sites with different soils, namely sandy loam at Hoai Duc Agrometeorologyl  Center, it may be concluded that the testing of both the radiometric  equipment and the method for soil moisture retrieval was very successful,  and the main goal of the experiments was fulfilled.
From Micro Gravitational Waves to the Quantum Indeterminism
Authors: Thuan Vo Van
Published: April 2018

An attempt to search for the links b etween general relativity and quantum mechanics is prop osed which bases on an extended space-time symmetry. A simplified cylindrical mo del of gravitational geometrical dynamics leads to a micro geo desic description of strongly curved space-time which implies a duality b etween quantum mechanical equations and the emission law of a sp ecific mo de of micro gravitational waves.
Monte-Carlo Study of the Collective Behavior in Animal Group: A \(q\)-state Potts model
Authors: The Nguyen Phuoc , Thanh Ngo Van
Published: April 2018

We study in this work the phase transition behaviour of animal groups. We assume that the individuals in the group have two classes of state. One is the internal state which can be either excited or non-excited. The other one is characterized by their orientation or direction of motion, it is so called the external state.The internal state plays an important role in the rules of interaction between the individuals.The system is put under a source of external perturbation called ``noise", the individuals can freely move from one site to another site on a two-dimension triangular lattice. We use the Monte-Carlo simulation technique for studying the behavior of the model with varying noise. For simplicity, we consider the orientation of individuals which has $q$ states as in the Potts model. We show that the system has three phases which correspond to the uncollected, flocking and runaway behaviors at very low, medium and high noise, respectively. These phases are separated by two first-order transitions.
Superheavy Dark Matter in the Supersymmetric Economical 3-3-1 Model
Authors: Huong Do Thi
Published: April 2018

We suggest the supersymmetric particles contained in the supersymmetric economical 3-3-1model were produced during the heating time. They have not been thermodynamic equilibrium when it frozeout. It leads to the lightest supersymmetric particle can be a good candidate for superheavy dark matter.With assumption the lightest supersymmetric particle is Bino, we show that the correct contribution of thesuperheavy dark matter species to the present critical density requires the Bino mass is order 1012 GeVand there is not exists a large mass hierarchy of the superpartner in the considered model.
Cross Sections for the \(^{nat}\)Zr\((p,xn)^{89,90}\)Nb Reactions Induced by 27.7 MeV Protons
Authors: Khue Pham Duc , Do Nguyen Van , Anh Le Tuan
Published: April 2018

The cross-sections for the formation of \(^{89}\)Nb and  \(^{90}\)Nb radionuclides in proton induced nuclear reactions on zirconium  were measured by using the well known activation method. The natural  zirconium (\(^{nat}\)Zr) target and copper (\(^{nat}\)Cu) monitor foils were  irradiated by 27.7 MeV proton beam at the MC50 Cyclotron of the Korea  Institute of Radiological and Medical Science (KIRAMS), Korea. The induced  gamma activities of the reaction products were measured by a coaxial high  purity germanium (HPGe) detector coupled to a PC-based multichannel  analyzer. The obtained cross sections for each nuclide are compared with  those existing in literature and with the theoretical cross sections  calculated by the TALYS - 1.4 code.
Appearance of an ensemble solitary pulse train in transient backward stimulated Raman scattering
Authors: Thang Nguyen Manh
Published: April 2018

A self-similarity approximation model for three-wave resonant interaction in transient backward stimulated Raman scattering (BSRS) was derived. Interestingly, as its asymptotic solution, the train of solitary backward Raman pulse train is possibly formed. This result can be considered as an increment of “single” soliton observed previously [A. Abdolvand et al., Phys. Rev. Lett 103, 183902 (2009)].
Mean-field Study of \(^{12}\)C+\(^{12}\)C Fusion
Authors: Chien Le Hoang , Cuong Do Cong , Khoa Dao Tien
Published: April 2018

The nuclear mean-field potential arising from the \(^{12}\)C+\(^{12}\)C interaction at the low energies relevant for the astrophysical carbon burning process has been constructed within the double-folding model, using the realistic nuclear ground-state density of the \(^{12}\)C nucleus and the effective M3Y nucleon-nucleon (NN) interaction constructed from the G-matrix of the Paris (free) NN potential. To explore the nuclear medium effect, both the original density independent M3Y-Paris interaction and its density dependent CDM3Y6 version have been used in the folding model calculation of the \(^{12}\)C+\(^{12}\)C potential. The folded potentials at the different energies were used in the optical model description of the elastic \cc\ scattering at the energies around and below the Coulomb barrier, as well as in the barrier penetration model to estimate the fusion cross section and astrophysical $S$ factor of the \(^{12}\)C+\(^{12}\)C reactions at the low energies. The obtained results are in a good agreement with experimental data over a wide range of energies.
Kinetic mixing in models with an extra Abelian gauge symmetry
Authors: Tran Hieu Minh
Published: April 2018

The Lagrangian of a theory possessing two Abelian gauge symmetries may contains a gauge kinetic mixing term without violating any known symmetries. In this paper, the formulation of theories extended by an additional Abelian gauge symmetry in the superfield formalism is presented. By rotating in the space of the gauge fields, the gauge kinetic mixing term can be eliminated, and the relevant charge and coupling are shifted in comparison with the original quantities. This process is valid for both theories with or without supersymmetry. We demonstrate, for example, the effect of the gauge kinetic mixing term in  the case of the U(1) extension of the minimal supersymmetric standard model. Various physical observables are computed for a given benchmark point. We find that the gauge kinetic mixing is important for the model to predict the observables in a good agreement with experimental data.
Effect of TiO\(_2\) anatase nanocrystallite on electrical properties of PPy/TiO\(_2\) nanocomposite
Authors: Duong Huyen Ngoc , Nguyen Thanh-Phuong , Nguyen Tung Trong
Published: April 2018

Polypyrrole/titanium dioxide nanocomposite (PPy/TiO2) was synthesized by in-situ chemical polymerization of pyrrole (Py) monomer in colloidal suspension of TiO2 anatase. TEM images show that TiO2 anatase nanoparticles with size of around 3–4 nm are randomly imbedded on the surface and inside of PPy grain. The random distribution of TiO2 anatase nanoparticle in PPy matrix form variety of p-n contact on the surface and inside of the materials. As expectation, the charge exchange between oxygen and the PPy affect the p-n depletion regions and then modify the electrical properties of PPy. Upon exposure to the open air the conductivity of the PPy/TiO2 nanocomposite exhibits an increase of about 20 folds much larger than that of neat PPy. The enhancement is accounted for the modification of in the surface conductance of PPy/TiO2 nanocomposite as a combination of the TiO2 coupling and oxygen interaction.
Trapping electrons in a circular graphene quantum dot with Gaussian potential
Authors: Nguyen Nhung T. T.
Published: April 2018

We study the dependence of trapping time of an electron in a circular graphene quantum dot depends on the electron's angular momentum and on the parameters of the external Gaussian potential used to induce the dot. The trapping times are calculated through a numerical determination of the quasi-bound states of electron from the two-dimensional Dirac-Weyl equation. It is shown that on increasing the angular momentum, not only does the trapping time decreases but also the trend of how the trapping time depends on the effective radius of the dot changes. In particular, as the dot radius increases, the trapping time increases for m<3 but decreases for m > 3. The trapping time however always decreases upon increasing the potential height. It is also found that the wave functions corresponding to the states of larger trapping times or higher m are more localized in space.
The Process of \(e^+e^- \to \mu^+\mu^-\) in the Randall - Sundrum Model, Supersymmetric Model and Unparticle Physics
Authors: Nguyen Hau Thi , Dao Thuy Thi Le
Published: April 2018

The process of \(e^+e^- \to \mu^+\mu^-\) in the Randall – Sundrum model, Supersymmetric model and Unparticle physics were studied in detail. The differential cross section and total cross section with different transmitted when polarized and non-polarized are compared and the numerical evaluation shows that they depend strongly on different transmitted.
Genome sequencing in plants and the genus Panax L.
Authors: Hiền Lê Thị Thu , Boer Hugo De , Manzanilla Vincent , Huân Hà Văn , Hải Nông Văn
Published: April 2018

Advances in genome sequencing technologies have created a new genomic era of life sciences research worldwide in which a number of modern and sophisticated techniques and tools have been developed and employed. Many countries have invested in plant genome sequencing as part of a sustainable development strategy. Each year, the number of plant genomes and transcriptomes sequenced has increased. The results obtained offer opportunities for fundamental and applied research, provide valuable data for identification of genes or molecular markers linked to traits that are important for selection, cultivation, and/or production. In Vietnam, partial or complete genome sequencing of crops has been recently conducted, primarily as part of international collaborative projects. The genus Panax L. (Araliaceae family) is comprised of several species of commercial value with narrow distributions such as P. bipinnatifidus Seem., P. stipuleanatus H.T.Tsai & K.M.Feng, and Panax vietnamensis Ha et Grushv. Despite their very important roles in traditional medicine, understanding of their genetic characteristics is still limited. Molecular studies on the genus have, so far, only evaluated limited markers for phylogenetic analysis. Therefore, genome sequencing of these important herbal plants is needed to understand their genetic characteristics, their evolutionary history and the genes and biochemical pathways contributing to medicinally important metabolites. This review summarizes all related genome sequencing technologies including the most recent advances in the last decade and their applications in genome and transcriptome sequencing of plants in general and in the genus Panax L. in particular.
Identification of missense mutations of the KCNJ5 gene on patients suffering from aldosterone-production adenomas in adrenal cortex
Authors: Việt Lê Bắc , Lan Hoàng Thị , Anh Lương Thị Lan , Hoàng Nguyễn Huy
Published: April 2018

Aldosterone is an important hormone in the adrenal gland as well as the human body. It is responsible for regulating salt and water in the body, therefore controlling blood pressure. Primary aldosteronism (also known as aldosterone producing while suppressing renin) plays a significant role in the pathophysiology of hypertension. Mutation in the KCNJ5 gene which leads to aldosterone-production adenomas is the main cause of primary aldosteronism. In this study, the entire coding sequence of the KCNJ5 gene including 2 exons was amplified and directly sequenced to detect mutations. The result revealed that two missense mutations were identified in two patients with hypertension and an apparent mass on the adrenal gland. A heterozygous mutation, D223V, is a novel mutation while the homozygous mutation, Q282E, was known as a polymorphism that had a significant effect on viability of the H295R cell line and K+ conduction channel. Analysis of the 3D protein structural model of the mutants clarified the relationship between genotype and phenotype of the two patients. These results partially pointed out causes of the adrenal gland adenomas and endocrine disorders in the the patient.