https://dspace.ctu.edu.vn/jspui/handle/123456789/2023 Vietnam Academy of Science and Technology 2026-04-11T23:23:49Z https://dspace.ctu.edu.vn/jspui/handle/123456789/110744 Title: Effects of temperature and relative humidity on resonant frequency of mems cantilever resonators under atmospheric pressure Authors: Nguyen, Chi Cuong; Phan, Minh Truong; Trinh, Xuan Thang; Le, Quoc Cuong; Ngo, Vo Ke Thanh Abstract: In this study, the effects of temperature and relative humidity on the resonant frequency of a micro-electro-mechanical system (MEMS) cantilever resonator under atmospheric pressure (p=101325 Pa) are discussed. The squeeze film damping (SFD) problem of MEMS cantilever resonators is modeled by solving the modified molecular gas lubrication (MMGL) equation, the equation of motion of micro-cantilever, and their appropriate boundary conditions, simultaneously in the eigen-value problem. The effective viscosity (µeff(RH, T)) of moist air is utilized to modify the MMGL equation to consider the effects of temperature and relative humidity under atmospheric pressure. Thus, the effects of temperature (T) and relative humidity (RH) on the resonant frequency of MEMS cantilever resonators over a wide range of gap thicknesses and under atmospheric pressure are discussed. The results showed that the frequency shift increases as the relative humidity and temperature increase. The influence of relative humidity on the resonant frequency becomes more significant under conditions of higher temperature and smaller gap thickness. 2022-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/110743 Title: Numerical simulation for determination of temperature field and residual stress of stainless steel butt joints with and without clamping Authors: Nguyen, Tien Duong Abstract: Many welded structures are fabricated from stainless steels because these steels have good mechanical properties and good corrosion resistance. It is necessary to predict the residual stress after welding in order to evaluate the performance of the welded joint. In this paper, the butt welded joint of AISI 316L stainless steel plates is studied. The Metal Inert Gas (MIG) welding process is selected for this material. A SYSWELD software based on the Finite Element Method (FEM) is used to determine the temperature field and residual stresses of two stainless steel plates. The welding simulation includes a sequential coupled thermomechanical analysis. The elemental generation and death technique is utilized to simulate metal deposition in welding. The double ellipsoidal heat source model is used for the heat input of the MIG welding process. The temperature distribution for various time steps at some important points is presented. Cooling times and cooling rates over a temperature range of 800⁰C to 500⁰C at these points are determined. The residual stress distribution in the longitudinal and transverse direction in two cases with and without clamping is obtained and compared. Obtained results show that: the temperature field in the case of clamping is the same as in the case of no clamping; only the longitudinal stress and transverse stress components are important, the other stress components are not important; the longitudinal stress at the middle of weld line is very high; the transverse stress in the case of clamping is greatly increased, so it is necessary to limit clamping to reduce residual stress after welding. 2022-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/110742 Title: Network approaches for identification of human genetic disease genes Authors: Nguyen, Minh Tan; Tran, Tien Dzung Abstract: The identification of genes causing a genetic disease is still an important issue in the biomedical field because the list of disease genes is still incomplete while it determines the early diagnosis and treatment of fatal genetic diseases such as autism, cancer, drug resistance, and secondary hypertension. Genes associated with a particular disease or similar diseases tend to reside in the same region in a biological network and their location on the network can be predicted. Many network analysis methods have been proposed to solve this problem so far. This review first helps readers access and master the basic concepts of biological networks, disease genes, and their properties. Then, the main content is devoted to the analysis and evaluation of analytical methods recently used to find disease genes on two networks: protein-protein interaction (PPI) and cellular signaling network (CSN). We reported typical problems of identification of primary genes that cause genetic diseases and modern techniques that were widely used for solving those problems. For each technique, we also represented key algorithms so that the audience can exactly implement them for their experiments. In particular, we evaluated the performance of these algorithms in prediction of disease genes and suggested the context for their usage. Finally, the implications of the methods are discussed and some future research directions are proposed. Taken together, disease genes can often be identified from network data by two approaches: network-based methods and machine learning-based methods, and the network-based approach showed better performance in most cases because it works well even if the data size is small. 2022-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/110741 Title: Analyzing movement behavior of zebrafish in different sized confined areas Authors: Quach, Kha Quang; Nguyen, Quoc Anh Abstract: Movement behavior of zebrafish (Danio rerio) was analysed according to different sizes of observation arena (four sizes: 5×5cm², 10×10cm², 15×15cm² and 30×30cm²). The observation arena was separated into corner, boundary and central areas based on experimental data. The results showed that the shapes of the corner, boundary and central areas were accordingly different in different sizes of the arena. Individuals stayed in the boundary zone for a substantial proportion (approximately 55-58%) of the observation period while in the corner zone they stayed for the shortest time period (approximately 12-14%). Movement parameters (speed, acceleration, etc.) of each individual varied in different areas on different sizes and speed was highest in the size of 15x15cm² while acceleration was highest in the size of 30x30cm². These reveal that the movement behaviors of zebrafish were affected by different sizes of arenas, at larger sizes they move more actively compared to smaller sizes. However, Transition probability matrices (TPMs) of moving between different areas in the observation were stable. These findings imply that there is a stereotypic inner state that maintains basic behaviors in animals. Information from this work would provide backgrounds of real-life process mechanism and would be useful for monitoring in response to environmental changes in practical aspect and be applicable to a wide range of fields including pharmacology, neurology, and genetics. 2022-01-01T00:00:00Z