Vietnamese German University
Vietnamese German University
Nguyen H.M.,Vietnamese German University
Proceedings - 2017 International Conference on Recent Advances in Signal Processing, Telecommunications and Computing, SigTelCom 2016 | Year: 2017
Functional Magnetic Resonance Imaging (fMRI) has been valuable to the current understanding of brain function and pre-operative evaluation of patients. In the recent years, the technique has been increasingly applied to the cases when the subject is at rest, also referred to as the resting-state fMRI. Resting-state fMRI measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal to investigate the functional topology of the brain. It is possible to identify various anatomically distinct areas of the brain that demonstrate synchronous BOLD fluctuations at rest, also referred to as the brain functional networks. Conventional approach to extract these functional dynamics is the datadriven Independent Component Analysis (ICA) method. In this work, we propose to utilize sparse representations for identifying functional connectivity networks. Specifically, fMRI signals are decomposed into morphological components which have sparse spatial overlap. Allowing sparse spatial overlap between components is a more physically plausible assumption to the statistical independence assumption of the conventional ICA method. The dictionary is learnt from the data using a K-SVD algorithm. Experimental results show that the proposed MCA-KSVD method can be used as an alternative to the conventional ICA method. © 2017 IEEE.
Pham D.T.,Vietnamese German University |
Le T.,Vietnamese German University
Computers and Mathematics with Applications | Year: 2017
We prove a posteriori upper and lower bounds for the error estimates when solving the Laplace-Beltrami equation on the unit sphere by using the Galerkin method with spherical splines. Adaptive mesh refinements based on these a posteriori error estimates are used to reduce complexity and computational cost of the corresponding discrete problems. The theoretical results are corroborated by numerical experiments. © 2017 Elsevier Ltd.
Tran T.T.H.,Vietnamese German University
Proceedings - 2016 International Conference on Advanced Computing and Applications, ACOMP 2016 | Year: 2016
We show a collection of scripts, called G-strongly positive scripts, which is used to recognize critical configurations of a CFG (chip firing game) on a multi-digraph with a global sink. Moreover, an algorithm for finding the minimum G-strongly positive script is also given. From that we generalize a very recent result by Aval et.al which prove the non-stableness of configurations obtained from a critical configuration by firing inversely any non-empty multi-subset of vertices for digraphs. © 2016 IEEE.
Le Luu T.,Vietnamese German University
Environmental Science and Pollution Research | Year: 2017
This paper reviews the current quality of groundwater in Vietnam. In Vietnam, groundwater is obtained primarily from tubewells, which have high concentrations of pollutants such as As, Fe, Mn, and NH4 +. In the areas where groundwater tests were conducted, arsenic levels ranged from 0.1–3050 μg/L, which substantially exceed the standard of 10 μg/L which has been established by the WHO. Contamination sources are distributed over a large area from the Red River Delta in the north to the Mekong River Delta in the south, putting as many as ten million people at risk of adverse health effects. Levels of arsenic and iron in sediment are strongly correlated, which indicate that the presence of arsenic in groundwater results from the reduction of arsenic bound to iron oxyhydroxides. It is important to raise awareness of these issues among the Vietnamese public by disseminating information about the negative effects of contaminated drinking water, as well as carrying out long-term research projects to identify other sources of contamination and improving water treatment technology and water management capabilities. © 2017 Springer-Verlag GmbH Germany
Jones L.R.,Valdosta State University |
Cherry C.R.,University of Tennessee at Knoxville |
Vu T.A.,Vietnamese German University |
Nguyen Q.N.,University of Transport and Communications
Transportation Research Part A: Policy and Practice | Year: 2013
Many Asian cities are experiencing rapid growth in the ownership of personal gasoline-powered motorcycles, a shift away from relatively low-emitting modes of transportation that is contributing to deteriorated air quality. Electric two-wheelers have the potential for significant air pollution reductions as an alternative to gasoline-powered motorcycles; however, they have yet to penetrate many Asian markets. While previous research has examined the adoption of cleaner alternatives to gasoline-powered automobiles (e.g., hybrid electric cars), similar work on motorcycle alternatives is lacking. This study uses a stated preference survey of households in Hanoi, Vietnam to analyze adoption of electric two-wheelers, while focusing on the effects of economic incentives (e.g., differential sales taxes and fuel prices) and technological improvements (e.g., more efficient batteries). A choice model is estimated and market shares are calculated for scenarios involving different levels of electric two-wheeler technology, gasoline prices, and sales tax rates. Results indicate that technological improvements and economic incentives, particularly sales taxes, have significant effects on adoption. © 2013 Elsevier Ltd.
Le T.P.L.,Vietnamese German University |
Trinh T.A.,Ton Duc Thang University
Procedia Engineering | Year: 2016
Traffic congestion and transportation-related environmental pollution are identified as the severe problems in many countries all over the world, especially in the developing countries, and Vietnam is also not an exception. In the context of Ho Chi Minh City, the biggest city located in Southern in Vietnam, millions of student and employee annually immigrate there to live, work and study; therefore, encouraging them to use bus service to reduce pressure on urban environment and traffic and transport is significant. The goal of this study was to recognize the behaviour of mode choice among student and employee using disaggregate model. To achieve this goal, binary logit model was used under disaggregate choice method. The findings indicated that, for student, 'Gender', 'Motorcycle ownership', 'Travel time', 'Travel distance', 'Migrant status', 'Convenience', 'Safety', and 'Awareness' affected their mode choices; for employee, 'Married', 'Income', 'Children', 'House ownership', 'Motorcycle ownership', 'Migrant status', 'Travel cost', 'Travel distance', 'Convenience', 'Safety', 'Awareness', and 'Social norms' played vital roles in their choices of means of transport. Besides, although motorcycle was the premier transport mode for both employee and student every day, they showed their perceptions of the negative sides of motorcycle to environment and community, and also expressed their willingness to switch to travel by bus if public transportation infrastructure and quality were upgraded. © 2016 The Authors. Published by Elsevier Ltd.
Le K.C.,Ruhr University Bochum |
Nguyen B.D.,Vietnamese German University
International Journal of Engineering Science | Year: 2012
Within continuum dislocation theory (CDT) the energy functional of a bent beam, made of a single crystal having only one active slip system, is asymptotically analyzed. By relaxing the smooth minimizer of this energy functional, we construct a sequence of piecewise smooth displacements and piecewise constant plastic distortions reducing the energy and exhibiting polygonization. The number of polygons can be estimated from above by equating the surface energy of small angle tilt boundaries to the contribution of the gradient terms from the smooth minimizer in the bulk energy. The comparison with Gilman's experimental results shows a good agreement. © 2012 Elsevier Ltd. All rights reserved.
Nguyen-Xuan H.,Vietnamese German University |
Hoang T.,Iuss Instituto Universitario Of Studi Superiori |
Nguyen V.P.,University of Cardiff
Computers and Mathematics with Applications | Year: 2014
A novel and efficient approach which is based on the framework of isogeometric analysis for elliptic homogenization problems is proposed. These problems possess highly oscillating coefficients leading to extremely high computational expenses while using traditional finite element methods. The isogeometric analysis heterogeneous multiscale method (IGA-HMM) investigated in this paper is regarded as an alternative approach to the standard finite element heterogeneous multiscale method (FE-HMM) which is currently an effective framework to solve these problems. The method utilizes non-uniform rationalB-splines (NURBS) in both macro and micro levels instead of standard Lagrange basis. Besides the ability to describe exactly the geometry, it tremendously facilitates high-order macroscopic/microscopic discretizations thanks to the flexibility of refinement and degree elevation with an arbitrary continuity level provided by NURBS basis functions. Furthermore, the nearly optimal quadrature rule for IGA (Auricchio et al., 2012) introduced recently is utilized to reduce significantly the number of micro problems, which is the main factor contributing into the computational cost in heterogeneous multiscale method. A priori error estimates of the discretization error coming from macro and micro meshes and optimal micro refinement strategies for macro/micro NURBS basis functions of arbitrary orders are derived. An efficient coupling between degrees of macro and micro basis functions is introduced. Numerical results show the excellent performance of the proposed method. © 2014 Elsevier Ltd. All rights reserved.
Nguyen M.,Vietnamese German University |
Truong M.,Vietnam University of Commerce
Procedia CIRP | Year: 2016
The term "sustainable development" has been a catch-all phrase in recent years. Corporate Social Responsibility (CSR) is seen as one of the media for sustainable development. In some countries, CSR has received much attention and achieved certain successes. However, in many other countries including Vietnam, perception of CSR remains vague and the adoption of CSR is limited. This study reviews different approaches to CSR and gives a conceptual framework of how cultural values influence CSR perception of enterprise. Some analysis on culture and data collection in Vietnam's case are carried out as example for the proposed framework. The study suggests several directions for future research on CSR. © 2016 The Authors. Published by Elsevier B.V.
Binh N.T.,Vietnamese German University |
Tuan V.A.,Vietnamese German University
Procedia CIRP | Year: 2016
The freight transport related greenhouse gas emission has been increasing quickly in Vietnam. Vietnamese government is aiming for CO2 reduction, which focuses on accurate definition of the contribution of different industry sectors to greenhouse gas emission. The objective of this paper is a summary of studies on transport emission factors in Vietnam and other countries in the world. As a consequence, the conclusion on emission factors currently used in Vietnam is generated. The study takes the rice industry in Vietnam as an example sector for the detailed examination of total emission. The preliminary results show that nearly 100 tons of CO2 were emitted from freight movement in the rice industry in 2011, approximately 0.8% of total CO2 emission borne by freight transport sector of Vietnam. Besides, modal shift from the road to inland waterway transport in the rice supply chain can bring benefits for not only the rice industry but also environmental protection. © 2016 The Authors. Published by Elsevier B.V.