Dynamic response and vibration of composite double curved shallow shells with negative Poisson's ratio in auxetic honeycombs core layer on elastic foundations subjected to blast and damping loads

Duc, Nguyen Dinh,Seung-Eock, Kim,Cong, Pham Hong,Anh, Nguyen Tuan,Khoa, Nguyen Dinh Elsevier 2017 International journal of mechanical sciences Vol.133 No.-

<P><B>Abstract</B></P> <P>The purpose of the present study is to investigate dynamic response and vibration of composite double curved shallow shells with negative Poisson's ratios in auxetic honeycombs core layer on elastic foundations subjected to blast and damping loads using analytical solution. This study considers composite double curved shallow shells with auxetic core which have three layers in which the top and bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure using the same aluminum material. Based on the first order shear deformation theory (FSDT) with the geometrical nonlinear in von Karman and using Airy stress functions method, Galerkin method and the fourth-order Runge–Kutta method, the resulting equations are solved to obtain expressions for nonlinear motion equations. The effects of geometrical parameters, material properties, elastic foundations Winkler and Pasternak, the nonlinear dynamic analysis and vibration of double curved shallow shells with negative Poisson's ratios in auxetic honeycombs core layer are studied.</P> <P><B>Highlights</B></P> <P> <UL> <LI> To investigate dynamic response and vibration of composite double curved shallow shells by using analytical solution. </LI> <LI> The composite shells have the central auxetic core layer—honeycomb structures with negative Poisson's ratio. </LI> <LI> Based on the first order shear deformation theory (FSDT). </LI> <LI> Used airy stress functions, Galerkin method and fourth-order Runge–Kutta method. </LI> <LI> The effects of geometrical parameters, material properties, elastic Winkler and Pasternak foundations, mechanical and blast loads are studied. </LI> </UL> </P>

Impacts of Perceived Security and Knowledge on Continuous Intention to Use Mobile Fintech Payment Services: An Empirical Study in Vietnam*

Dat Dinh NGUYEN,Thanh Duc NGUYEN,Trung Duc NGUYEN,Ha Viet NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8

Stepping into the technological boom time, Vietnam has integrated into the trends of using Fintech applications as a new means of payment. This article evaluates the relationship between perceived security (including service security and platform security), knowledge, confirmation, perceived usefulness, satisfaction, attitude and lastly enterprise’s images regarding the service and continuous intention to use Fintech services. The survey results of 352 Vietnamese customers using Fintech services, reliability test and extended post-acceptance model (EPAM) which is based on PAM and ECT models. From the survey, we further found out that perceived security (BSS) has no direct impact on continued intention to use, while perceived security (BSS) has positive impact on confirmation (CON), similarly, perceived usefulness (PU) and user’s satisfaction (SES). Knowledge of the Mobile Fintech payment service (KNOW) has a positive impact on perceived security (BSS). Confirmation (CON) has a positive influence on perceived usefulness but in the meanwhile it has created a negative impact on user’s satisfaction (SES). From the survey it can also tell that user’s attitude (ATT) and enterprise image (IMG) both have a positive impact on continual intention to use Fintech services. From the research results, we also propose some recommendation to enhance the continual intention to use Fintech services in Vietnam.

Highly effective adsorption of organic dyes from aqueous solutions on longan seed-derived activated carbon

Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Mau Thanh,Nguyen Duc Vu Quyen,Vo Thang Nguyen,Dao Ngoc Nhiem,Dinh Quang Khieu 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.3

In this study, longan seeds - an agricultural by-product was used to fabricate activated carbon (LSAC) through two-step pyrolysis with pre-carbonization at low temperature in the first step and then activation by H3PO4. LSAC with large surface area and porous structure exhibits an excellent capacity of absorption towards both cationic dyes (methylene blue (MB), rhodamine-B (RhB)) and anionic dyes (methyl orange (MO), congo red (CR)). Experimental data can be described well by the pseudo-second kinetic model. The maximum adsorption capacity based on Langmuir isotherm model was found as 502.84; 397.77; 464.66 and 350.64 mg.g−1 for MB, RhB, MO and CR, respectively. The adsorption of MB, RhB and CR on LSAC is spontaneous and endothermic, while that for MO is spontaneous but exothermic. Furthermore, the adsorption mechanism of dyes on LSAC was also studied showing that it can occur by electrostatic interaction, hydrogen bonding, the filling of pores involving the interaction between dye ions with specific functional groups such as –OH, –COOH, –NH2 and –PO43− on the LSAC surface. These results suggest that LSAC material may be envisaged as a promising adsorbent for treatment of wastewater in textile industries.

Integrative Bioinformatics and Functional Analyses of GEO, ENCODE, and TCGA Reveal <i>FADD</i> as a Direct Target of the Tumor Suppressor BRCA1

Nguyen, Dinh-Duc,Lee, Dong Gyu,Kim, Sinae,Kang, Keunsoo,Rhee, Je-keun,Chang, Suhwan MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.5

<P>BRCA1 is a multifunctional tumor suppressor involved in several essential cellular processes. Although many of these functions are driven by or related to its transcriptional/epigenetic regulator activity, there has been no genome-wide study to reveal the transcriptional/epigenetic targets of BRCA1. Therefore, we conducted a comprehensive analysis of genomics/transcriptomics data to identify novel BRCA1 target genes. We first analyzed ENCODE data with BRCA1 chromatin immunoprecipitation (ChIP)-sequencing results and identified a set of genes with a promoter occupied by BRCA1. We collected 3085 loci with a BRCA1 ChIP signal from four cell lines and calculated the distance between the loci and the nearest gene transcription start site (TSS). Overall, 66.5% of the BRCA1-bound loci fell into a 2-kb region around the TSS, suggesting a role in transcriptional regulation. We selected 45 candidate genes based on gene expression correlation data, obtained from two GEO (Gene Expression Omnibus) datasets and TCGA data of human breast cancer, compared to BRCA1 expression levels. Among them, we further tested three genes (<I>MEIS2</I>, <I>CKS1B</I> and <I>FADD</I>) and verified <I>FADD</I> as a novel direct target of BRCA1 by ChIP, RT-PCR, and a luciferase reporter assay. Collectively, our data demonstrate genome-wide transcriptional regulation by BRCA1 and suggest target genes as biomarker candidates for BRCA1-associated breast cancer.</P>

Detection of pathogenic microorganisms using biosensor based on multi-walled carbon nanotubes dispersed in DNA solution

Nguyen Thi Thuy,Phuong Dinh Tam,Mai Anh Tuan,Anh-Tuan Le,Le Thi Tam,Vu Van Thu,Nguyen Van Hieu,Nguyen Duc Chien 한국물리학회 2012 Current Applied Physics Vol.12 No.6

The present paper introduces a facile and cost-effective route for the direct dispersion of multi-walled carbon nanotubes (MWCNTs) in DNA solution. Their application in detecting Escherichia coli O157:H7using DNA biosensorwas demonstrated. The dispersion state of theMWCNTswas characterized via UVeVis spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy. The interaction between DNA sequence and the MWCNTs was investigated using Raman spectroscopy and Fourier transform infrared spectroscopy. As-obtainedMWCNT solutionwas used in the preparation of DNA sensor. Results revealed that the developed DNA sensor can detect a DNA target as low as 1 nM in a buffer solution. The sensitivity of the DNA sensor reached approximately 0.19 nM/mV. The effect of dispersion parameters, including pH values, DNA concentration, ion strength, and sonication time, on sensor response was also studied. TheDNA sensor can respondwell to 120 min of sonication time, a pH value of 9, and 20 mM of DNA sequence concentration. The results of the present study showed a potential application of the DNA sensor in the detection of Escherichia coli O157:H7.

Potential of integrated vertical and horizontal flow constructed wetland with native plants for sewage treatment under different hydraulic loading rates

Nguyen, Xuan Cuong,Nguyen, Dinh Duc,Thi Loan, Nguyen,Chang, Soon Woong IWA Publishing 2017 Water Science & Technology Vol.76 No.2

<P>In this study, a pilot-scale integrated constructed wetland with vertical flow (VF) and horizontal flow (HF) in series was designed and investigated to evaluate sewage wastewater treatment capacity. The VF unit was planted with <I>Canna indica</I> and was 1.2 m long, 1.2 m wide, and 1.2 m high; whereas the HF unit contained <I>Colocasia esculenta</I> and was 3.0 m long, 1.0 m wide, and 1.0 m high. The system was operated under different hydraulic loading rates (HLRs) of 0.1, 0.2, and 0.15 m/d. The effluent concentrations differed as HLR changed, and the means were total suspended solids (TSS): 87 mg/L; biological oxygen demand (BOD<SUB>5</SUB>): 31 mg/L; chemical oxygen demand (COD<SUB>Cr</SUB>): 59 mg/L; ammonium nitrogen (NH<SUB>4</SUB>-N): 5.3 mg/L; nitrate nitrogen NO<SUB>3</SUB>-N: 8.4 mg/L; total nitrogen (TN): 7.1 mg/L; phosphate (PO<SUB>4</SUB>-P): 0.9 mg/L; and total coliforms (TCol): 1,485 most probable number (MPN)/100 mL. The average removal efficiencies for TSS, BOD<SUB>5</SUB>, TN, NH<SUB>4</SUB>-N, PO<SUB>4</SUB>-P, and TCol were 28.3, 74.9, 79, 76.2, 3.6, and 82%, respectively. There were significant differences in the effluent concentrations among the three HLRs (<I>P</I> < 0.05), except for PO<SUB>4</SUB>-P.</P>

Optimal control of vibration by multiple tuned liquid dampers using Taguchi method

Nguyen Van Khang,Do The Duong,Nguyen Thi Van Huong,Nguyen Duc Thi Thu Dinh,Vu Duc Phuc 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4

This paper investigates the multiple tuned liquid dampers (MTLD), which consist of a number of MTLD whose first natural frequencies of sloshing are distributed over a certain range around the natural frequency of a structure. The liquid motion in the MTLD as well as the MTLD-structure interaction are numerically simulated using a shallow water-wave theory. An optimal procedure based on Taguchi method is proposed to determine the optimum parameters of MTLD to suppress the vibration amplitude of the considered structure. A number of numerical tests are included to demonstrate and verify the effectiveness of the proposed procedure.

Formability improvement and blank shape definition for deep drawing of cylindrical cup with complex curve profile from SPCC sheets using FEM

Nguyen, Duc-Toan,Dinh, Duy-Khoe,Nguyen, Hong-Minh Thi,Banh, Tien-Long,Kim, Young-Suk Springer-Verlag 2014 Journal of Central South University Vol.21 No.1

Dry semi-continuous anaerobic digestion of food waste in the mesophilic and thermophilic modes: New aspects of sustainable management and energy recovery in South Korea

Nguyen, Dinh Duc,Chang, Soon Woong,Cha, Jae Hun,Jeong, Seong Yeob,Yoon, Yong Soo,Lee, Sin Jin,Tran, Minh Chi,Ngo, Huu Hao Elsevier 2017 Energy conversion and management Vol.135 No.-

<P><B>Abstract</B></P> <P>In this study, parallel, bench-scale, mesophilic and thermophilic, dry, semi-continuous anaerobic digestion (DScAD) of Korea food waste (FW, containing 22% total solids (TS) and 20% volatile solids (VS)) was investigated thoroughly under varying operational conditions, including hydraulic retention times (HRTs) and organic loading rates (OLRs). The aim was to evaluate the start-up, stability, overall removal efficiency, and inhibitory effects of toxic compounds on process performance over a long-term operation lasting 100days. The results from both digesters indicate that the simultaneous reduction of VS and the production of gas improved as the HRT decreased or the OLR increased. The highest average rates of VS reduction (79.67%) and biogas production (162.14m<SUP>3</SUP> biogas/ton of FW, 61.89% CH<SUB>4</SUB>), at an OLR of 8.62±0.34kgVS/m<SUP>3</SUP> day (25days of HRT), were achieved under thermophilic DScAD. In addition, the average rates of reduction of VS and the production of biogas in thermophilic DScAD were higher by 6.88% and 16.4%, respectively, than were those in mesophilic DScAD. The inhibitory effects of ammonia, H<SUB>2</SUB>S, and volatile fatty acids (VFAs) on methane production was not clear from either of the digesters, although, apparently, their concentrations did fluctuate. This fluctuation could be attributed to the self-adaptation of the microbial well. However, digestion that was more stable and faster was observed under thermophilic conditions compared with that under mesophilic conditions. Based on our results, the optimum operational parameters to improve FW treatment and achieve higher energy yields could be determined, expanding the application of DScAD in treating organic wastes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DScAD remained stable even at a high rate of organic loading. </LI> <LI> Higher OLR led to the more reduction of VS and the production of biogas. </LI> <LI> Thermophilic digesters had higher reduction of VS and the generation of biogas. </LI> <LI> Stable with faster digestion and higher OLR was achieved in the thermophilic operation. </LI> <LI> Acetic and propionic acids were the most prominent in the TVFA. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improving formability of tube bending for a copper material using finite element simulation

Duc-Toan Nguyen,Dinh-Thanh Nguyen,김영석 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

Bending tubes are key products in many industries. The geometric parameters of the bending process are considered according to Taguchi’sorthogonal array and then coupled with finite element simulation to predict and improve the formability of the tube bendingprocess for copper JIS25A material. Three parameters, namely, mandrel diameter, distance between mandrel rings, and distance from thetip of the mandrel bar to the center of the base die, are selected to study their effects on the quality of the bending process. The varianceanalysis shows that the effect distribution of each parameter to bending quality is determined, and optimal conditions are adopted to conductexperiments.