Application of ANFIS to the design of elliptical CFST columns

Ngoc-Long Tran,Trong-Cuong Vo,Duy-Duan Nguyen,Van-Quang Nguyen,Huy-Khanh Dang,Viet-Linh Tran Techno-Press 2023 Advances in computational design Vol.8 No.2

Elliptical concrete-filled steel tubular (CFST) column is widely used in modern structures for both aesthetical appeal and structural performance benefits. The ultimate axial load is a critical factor for designing the elliptical CFST short columns. However, there are complications of geometric and material interactions, which make a difficulty in determining a simple model for predicting the ultimate axial load of elliptical CFST short columns. This study aims to propose an efficient adaptive neuro-fuzzy inference system (ANFIS) model for predicting the ultimate axial load of elliptical CFST short columns. In the proposed method, the ANFIS model is used to establish a relationship between the ultimate axial load and geometric and material properties of elliptical CFST short columns. Accordingly, a total of 188 experimental and simulation datasets of elliptical CFST short columns are used to develop the ANFIS models. The performance of the proposed ANFIS model is compared with that of existing design formulas. The results show that the proposed ANFIS model is more accurate than existing empirical and theoretical formulas. Finally, an explicit formula and a Graphical User Interface (GUI) tool are developed to apply the proposed ANFIS model for practical use.

Design of a Nonisolated Fuel Cell Boost Charger for Lithium Polymer Batteries With a Low Output Ripple

Van-Long Tran,Ngoc-Tham Tran,Sun-Ho Yu,Yongjin Park,Woojin Choi IEEE 2015 IEEE transactions on energy conversion Vol.30 No.2

<P>In the design of a fuel cell charger, it is important to find a suitable topology and to design the converter to guarantee the performance of both the fuel cell and the battery. Most of the chargers developed so far have used step-down converters. However, since a small fuel cell stack can only generate a low voltage, it is necessary to use a step-up converter to charge batteries. In this paper, a nonisolated boost charger topology with an additional output inductor for a proton exchange membrane fuel cell is presented to meet the strict ripple requirements for the battery charge, and its control method using a proportional-integral (PI) controller is detailed. The feasibility of the boost charger and its control method is then verified through the experimental results.</P>

One-Pot Preparation of Antibacterial Electrospun Polycaprolactone Membrane Embedded with Gamma Irradiation-Induced Silver Nanoparticles

Chien Minh Tran,Ngoc Thi‑Thanh Nguyen,Minh Hieu Ho,Vinh Khanh Doan,Khanh Loan Ly,Nhi Ngoc‑Thao Dang,Nam Minh‑Phuong Tran,Hoai Thi‑Thu Nguyen,Long Phuoc Truong,Thai Minh Do,Quyen Ngoc Tran,Hien Quoc Ng 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

In this study, we proposed a straightforward electrospun polycaprolactone (PCL) loaded with silver nanoparticles (SNPs)membrane fabrication process, in which SNPs were directly synthesized from silver nitrate (AgNO3) in PCL–acetone mixtureby gamma irradiation. The insolubility of AgNO3in PCL solution was solved using an auxiliary dimethyl sulfoxide solvent. As a physical approach, gamma rays readily converted silver ions into SNPs without the addition of harmful reductionagents, which reduced the cytotoxicity of the synthesized material. By avoiding some processes such as purification, solventremoval, or redispersion of SNPs, this method was more time-saving compared to other related studies. SNPs formation wasconfirmed by both UV–Visible spectrum (UV–Vis) and X-ray diffraction analysis. Scanning electron microscopy (SEM)revealed that the addition of SNPs significantly reduced the fiber diameter of PCL–Ag membranes compared to that of rawPCL. Uniform spherical-shaped SNPs incorporated in PCL fibers were observed under transmission electron microscopy(TEM). The tensile test showed that the electrospun PCL–Ag membranes exhibited good mechanical characteristics. Moistureeasily penetrated the porous microstructure of PCL–Ag, facilitating wound humidity regulation. Inductively coupledplasma-mass spectroscopy (ICP-MS) was employed to study the release profiles of SNPs at different time intervals. Overall,the PCL–Ag 500 ppm sample exerted excellent antibacterial activity against Pseudomonas aeruginosa and Staphylococcusaureus strains and low in vitro cytotoxicity.

Exposure to Tobacco Advertising and Promotion among School Children Aged 13-15 in Vietnam - an Overview from GYTS 2014

Tran, Khanh Long,Phung, Xuan Son,Kim, Bao Giang,Phan, Thi Hai,Doan, Thi Thu Huyen,Luong, Ngoc Khue,Pham, Thi Quynh Nga,Nguyen, Tuan Lam,Hoang, Van Minh,Le, Thi Thanh Huong Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1

Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption and usage, especially in youth. Despite the regulation on prohibiting advertisement of any tobacco product, tobacco advertisement and promotion activities are still common in Vietnam. This article presents current exposure to tobacco advertising and promotion (TAP) among school children aged 13 to 15 years in Vietnam in 2014 and potential influencing factors. Data from the Global Youth Tobacco Survey 2014 in Vietnam covering 3,430 school aged children were used. Both descriptive and analytical statistics were carried out with Stata 13 statistical software. Binary logistic regression was applied to explain the exposure to TAP among youth and examine relationships with individual factors. A significance level of p<0.05 and sampling weights were used in all of the computations. In the past 30 days, 48.6% of the students experienced exposure to at least 1 type of tobacco advertising or promotion. Wearing or otherwise using products related to tobacco was the most exposure TAP type reported by students (22.3%). The internet (22.1), points of sales (19.2) and social events (11.5) were three places that students aged 13-15 frequently were exposed to TAP. Binary logistic results showed that gender (female vs male) (OR = 0.61, 95%CI: 0.52 - 0.71), susceptibility to smoking (OR = 2.12, 95%CI: 1.53 - 2.92), closest friends' smoked (OR = 1.43, 95%CI: 1.2 - 1.7) and parents smoking status (OR = 2.83, 95%CI: 1.6 - 5.01) were significantly associated with TAP exposure among school-aged children. The research findings should contribute to effective implementation of measures for preventing and controlling tobacco use among students aged 13-15 in Viet Nam.

Effect of hydrothermal time on the structure and property of graphene oxide membrane

Tran Van Khai,Pham Thuy Trang,Le Ngoc Long,Le Van Thang,Tran Duc Chau,Vuong Vinh Dat,Mai Thanh Phong 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

Two dimensional graphene oxide (GO) has potential application in membrane separation owing to its unique structure andphysicochemical properties. In this study, the reduced graphene oxide (rGO) was synthesized from GO via hydrothermaltreatment at 160 oC for 1, 2, 3 and 4 h, and the rGO membranes were prepared on cellulose nitrate supporting membranesby vacuum filtration. The structural change and chemical composition of GO were investigated using X-ray diffraction (XRD),Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM),atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) andcontact angle measurements. The result shows that uniformly intact rGO membranes with good hydrophobicity could beachieved by adjusting the reduction degree of GO through changing the hydrothermal reaction time. The huge improvementof the hydrophobic property of rGO could be attributed to the removal of the most the hydrophilic oxygen-containingfunctional groups on the surface of GO. Additionally, the structure, chemical composition, and d-spacing of the GO can alsobe controlled by adjusting the reduction time. This method holds great potential because it can be prepared in large quantitiesat low cost, and suitable for applications in membrane technologies.

Equivalent Convective Heat Transfer Coefficient for Boundary Conditions in Temperature Prediction of Early-Age Concrete Elements Using FD and PSO

Long Nguyen-Ngoc,Tu Anh Do,Viet Hai Hoang,Tuyet Thi Hoang,Tam Duc Tran 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

Engineering infrastructure includes a large number of concrete structures. The main binder used in concrete is Portland cement, which reacts with water when mixing. During the chemical reaction (cement hydration) heat is released causing non-uniform temperature distribution and subsequent internal stresses that may crack the concrete. Therefore, accurate prediction of concrete temperature evolution in design and control of concrete temperature in construction are crucial tasks for engineers. This paper presents the development of a finite difference (FD) model for predicting thermal behavior of concrete structures during cement hydration. A formwork or insulation layer that covers the outer of the concrete was accounted for in the model. The temperature profiles calculated by the proposed model show close agreement with those measured from a concrete bridge footing and a concrete cube. The Particle Swarm Optimization (PSO) algorithm was adopted to compute an “equivalent convection coefficient” for the convection boundary condition in the simplified model for several common insulation materials. The results show that using the simplified model along with an equivalent convection coefficient can give a significant reduction in the computation time while the accuracy is still maintained. In addition, an equation for estimating an equivalent convection coefficient for a given insulation material was developed for design and practical purposes. The proposed method can be used in the design of concrete structures and control of concrete temperature to prevent early-age thermal cracking thus ensuring the expected durability and service life. From the obtained results, varying equivalent convection values are also recommended to be used for different insulation materials.

SOC/SOH Estimation Method for AGM VRLA Battery by Combining ARX Model for Online Parameters Estimation and DEKF Considering Hysteresis and Diffusion Effects

Ngoc-Tham Tran,Kim-Hung Nguyen,Van-Long Pham,Abdul Basit Khan,Woojin Choi 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

State of Charge (SOC) and State of Health (SOH) are the key issues for the application of battery, since SOC/SOH estimation accuracy is crucial for optimizing battery energy utilization, ensuring safety and extending battery life cycles. In addition, Dual Extended Kalman Filter (DEKF) can provide an elegant and powerful solution in SOC/ SOH estimation based on the battery impedance model. However, battery parameters strongly depend on the operating condition such as SOC, current rate, temperature and the battery life cycle. In this research, a novel method for SOC/SOH estimation which combines DEKF algorithm considering hysteresis and diffusion effect and Auto Regressive with external input (ARX) method used for online parameters estimation is proposed. The DEKF provides the precise information of the battery open circuit voltage to the ARX model and the ARX model keeps monitoring the parameter variation and supply it to the DEKF. The validation of the demonstrated algorithm is proved by the experiments.

Controllable synthesis of MoS₂/graphene low-dimensional nanocomposites and their electrical properties

Long, Le Ngoc,Thi, Pham Tan,Trung Kien, Pham,Trung, Pham Thanh,Ohtani, Masataka,Kumabe, Yoshitaka,Tanaka, Hirofumi,Ueda, Shigenori,Lee, Hyoyoung,Thang, Phan Bach,Khai, Tran Van Elsevier 2020 APPLIED SURFACE SCIENCE - Vol.504 No.-

<P><B>Abstract</B></P> <P>In this study, a novel hydrothermal route has been developed for the synthesis of MoS<SUB>2</SUB>/graphene composite with controllable structures, in which ammonium molybdatetetrahydrate, as-prepared graphene oxide (GO), and thioacetamide were used as staring materials. Effects of Mo<SUP>4+</SUP>-to-C precursor ratios and crystalline time on the structures, components and morphologies of MoS<SUB>2</SUB>/graphene were investigated. MoS<SUB>2</SUB>/graphene samples were characterized using XRD, FESEM, HRTEM, FTIR, Raman spectroscopy, HAADF-STEM/EDS, HXPES and electrical measurements. The results show that petal-like MoS<SUB>2</SUB> nanostructures with ultrathin petals (~1–10 layers) and coexistence of 1T- and 2H-MoS<SUB>2</SUB> phases can be synthesized on graphene surface in a short time (~2 h). Comparison of crystallization conditions, we found that the crystallization time had a significant effect on the size of the MoS<SUB>2</SUB> nanopetals. The shorter the reaction time is, the thinner the petal-like MoS<SUB>2</SUB> nanoscale is. On the other hand, by adjusting the ratios of Mo<SUP>4+</SUP>to C (denoted as: MoS<SUB>2</SUB>/C (1:2), MoS<SUB>2</SUB>/C (3:2), MoS<SUB>2</SUB>/C (2.5:1) and MoS<SUB>2</SUB>/C (3:1)), different MoS<SUB>2</SUB>/graphene architectures including “sandwich-liked”, “layer–by–layer” and “anchored” can be obtained. On the basis of these results, a possible growth mechanism of MoS<SUB>2</SUB>nanopetals on GO was proposed. Interestingly, the as-synthesized material depicts its memristive behavior through the Volt-Ampere characteristics, suggesting a potential application in logic memory devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel hydrothermal route has been developed for the synthesis of MoS<SUB>2</SUB>/graphene composite with controllable structures. </LI> <LI> The effects of Mo<SUP>4+</SUP>-to-C precursor ratios and crystalline time on properties of MoS<SUB>2</SUB>/graphene were investigated by FESEM, HRTEM, XRD, FTIR, Raman spectroscopy, HAADF-STEM/EDS and HXPES. </LI> <LI> The memristive properties of the MoS<SUB>2</SUB>/graphenenanocomposite were presented. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Prediction of Critical Buckling Load of Web Tapered I-Section Steel Columns Using Artificial Neural Networks

Trong-Ha Nguyen,Ngoc-Long Tran,Duy-Duan Nguyen 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.4

The web tapered I-section steel (WTIS) columns have been widely used in civil and industrial steel structures. However, the existing theoretical and empirical equations demonstrate a signifi cant discrepancy in estimating the critical axial load of the WTIS columns. This study aims to develop eff ective artifi cial neural networks (ANNs) for predicting the critical buckling load of the WTIS columns. A database of 269 fi nite element models of WTIS columns was generated, after verifying with experimental results, to develop the ANN model. The results of the proposed ANN model were also compared with those of existing formulas, highlighting that the ANN model in this study predicts the critical buckling load of the WTIS columns more accurately than the existing formulas. Moreover, the infl uences of input parameters on the critical buckling load of the WTIS columns were thoroughly investigated. An ANN-based formula, which considers input variables, was thereafter proposed to estimate the critical buckling load of the WTIS columns. Additionally, a graphical user interface tool has been developed for simplifying the design practice of the WTIS columns.

Violation of Bans on Tobacco Advertising and Promotion at Points of Sale in Viet Nam: Trend from 2009 - 2015

Le, Thi Thanh Huong,Tran, Khanh Long,Phung, Xuan Son,Do, Phuc Huyen,Phan, Thuy Linh,Nguyen, Ngoc Bich,Nguyen, Xuan Lam,Le, Vu Anh,Tran, Thi Tuyet-Hanh Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1

Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control legislation in Viet Nam, but it has been established that violations of the bans are very common. This study was conducted to explore the trend in violations of bans on tobacco advertising and promotion at points of sale in Viet Nam in the past six years and to explore any differences in the violation situations before and after the Law on Tobacco Control came into effect on 1st May 2013. Quantitative data were collected through observation of violations of the bans on tobacco advertising and promotion at points of sale in 10 provinces throughout Viet Nam in four survey rounds (2009, 2010, 2011, and 2015). Variation in violation prevalence over time was examined by chi-square test using a Bonferini method. Binary logistic regression was employed to identify the factors that may have influences on different types of violation. A level of significance of p<0.05 was used for all tests in this article. The most common form of violation was the display of more than one pack/one carton of a cigarette brand. Violation of bans on tobacco advertising increased while violations on promotion ban and on displaying tobacco decreased through time. Some factors associated with the tobacco advertising and promotion bans included surveyed years, types of points of sale, regions and areas where the points of sale were located. The enforcement of the bans did not improve even after the issuance and the enactment of the Law on Tobacco Control. This suggests that the monitoring and enforcement of bans on tobacco advertising and promotion at points of sale should be strengthened. Penalties should be strictly applied for violators as indicated in the current tobacco control legislation.