An efficient approach for model updating of a large-scale cable-stayed bridge using ambient vibration measurements combined with a hybrid metaheuristic search algorithm

Tran N. Hoa,S. Khatir,G. De Roeck,Nguyen N. Long,Bui T. Thanh,M. Abdel Wahab 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.4

This paper proposes a novel approach to model updating for a large-scale cable-stayed bridge based on ambient vibration tests coupled with a hybrid metaheuristic search algorithm. Vibration measurements are carried out under excitation sources of passing vehicles and wind. Based on the measured structural dynamic characteristics, a finite element (FE) model is updated. For long-span bridges, ambient vibration test (AVT) is the most effective vibration testing technique because ambient excitation is freely available, whereas a forced vibration test (FVT) requires considerable efforts to install actuators such as shakers to produce measurable responses. Particle swarm optimization (PSO) is a famous metaheuristic algorithm applied successfully in numerous fields over the last decades. However, PSO has big drawbacks that may decrease its efficiency in tackling the optimization problems. A possible drawback of PSO is premature convergence leading to low convergence level, particularly in complicated multi-peak search issues. On the other hand, PSO not only depends crucially on the quality of initial populations, but also it is impossible to improve the quality of new generations. If the positions of initial particles are far from the global best, it may be difficult to seek the best solution. To overcome the drawbacks of PSO, we propose a hybrid algorithm combining GA with an improved PSO (HGAIPSO). Two striking characteristics of HGAIPSO are briefly described as follows: (1) because of possessing crossover and mutation operators, GA is applied to generate the initial elite populations and (2) those populations are then employed to seek the best solution based on the global search capacity of IPSO that can tackle the problem of premature convergence of PSO. The results show that HGAIPSO not only identifies uncertain parameters of the considered bridge accurately, but also outperforms than PSO, improved PSO (IPSO), and a combination of GA and PSO (HGAPSO) in terms of convergence level and accuracy.

The K\"{a}hler Different of a Set of Points in~$\pmpn$

Nguyen T. Hoa,Tran N. K. Linh,Le N. Long,Phan T. T. Nhan,Nguyen T. P. Nhi 대한수학회 2022 대한수학회보 Vol.59 No.4

Given an ACM set $\X$ of points in a multiprojective space $\pmpn$ over a field of characteristic zero, we are interested in studying the K\"ahler different and the Cayley-Bacharach property for $\X$. In $\bbP^1\times \bbP^1$, the Cayley-Bacharach property agrees with the complete intersection property and it is characterized by using the K\"ahler different. However, this result fails to hold in $\pmpn$ for $n>1$ or $m>1$. In this paper we start an investigation of the K\"ahler different and its Hilbert function and then prove that $\X$ is a complete intersection of type $(d_1,\ldots,d_m,d'_1,\ldots,d'_n)$ if and only if it has the Cayley-Bacharach property and the K\"ahler different is non-zero at a certain degree. We characterize the Cayley-Bacharach property of $\X$ under certain assumptions.

High Efficiency Dual-Bridge LLC Resonant Converter with Adaptive Frequency Control for On-Board Charger Applications

Tuyen D. Nguyen,Trinh Nguyen,Ravi Nath Tripathi,Long H. B. Nguyen,Minh V. Vo,Hai N. Tran 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper proposes an adaptive frequency control strategy for the unidirectional DC/DC converter based on Dual-bridge LLC (DBLLC) resonant converter to eliminate the circulating interval (CI), which causes high conduction loss. The LLC resonant converters are the preferred choice to select of DC/DC converter topology for on-board charger (OBC) due to it provides many advantages such as high efficiency, high power density. The DBLLC resonant converter operating with variable frequency and the pulse width-modulated (PWM) control will be applied as an isolated stage (DC/DC converter) of 400V-7.4 kW to improve the power density and efficiency of the whole system. The advantage of operating at the adaptive frequency is that the conduction loss in all devices will be reduced, while the soft switching technique is still achieved over the full load range. Furthermore, the detailed CI characteristic along with losses analysis is presented. The topology is designed for 400 VDC input to 220-380VDC output conversion, in the power range from 3.3 kW to 7.4kW. All theoretical analysis and the experimental results on the proposed converter are provided to verify the system performance.

Stearoyl Coenzyme A Desaturase 1 Is Associated with Hepatitis C Virus Replication Complex and Regulates Viral Replication

Nguyen, Lam N.,Lim, Yun-Sook,Pham, Long V.,Shin, Hae-Young,Kim, Yong-Sun,Hwang, Soon B. American Society for Microbiology 2014 Journal of virology Vol.88 No.21

<P>The hepatitis C virus (HCV) life cycle is tightly regulated by lipid metabolism of host cells. In order to identify host factors involved in HCV propagation, we have recently screened a small interfering RNA (siRNA) library targeting host genes that control lipid metabolism and lipid droplet formation using cell culture-grown HCV (HCVcc)-infected cells. We selected and characterized the gene encoding stearoyl coenzyme A (CoA) desaturase 1 (SCD1). siRNA-mediated knockdown or pharmacological inhibition of SCD1 abrogated HCV replication in both subgenomic replicon and Jc1-infected cells, while exogenous supplementation of either oleate or palmitoleate, products of SCD1 activity, resurrected HCV replication in SCD1 knockdown cells. SCD1 was coimmunoprecipitated with HCV nonstructural proteins and colocalized with both double-stranded RNA (dsRNA) and HCV nonstructural proteins, indicating that SCD1 is associated with HCV replication complex. Moreover, SCD1 was fractionated and enriched with HCV nonstructural proteins at detergent-resistant membrane. Electron microscopy data showed that SCD1 is required for NS4B-mediated intracellular membrane rearrangement. These data further support the idea that SCD1 is associated with HCV replication complex and that its products may contribute to the proper formation and maintenance of membranous web structures in HCV replication complex. Collectively, these data suggest that manipulation of SCD1 activity may represent a novel host-targeted antiviral strategy for the treatment of HCV infection.</P><P><B>IMPORTANCE</B> Stearoyl coenzyme A (CoA) desaturase 1 (SCD1), a liver-specific enzyme, regulates hepatitis C virus (HCV) replication through its enzyme activity. HCV nonstructural proteins are associated with SCD1 at detergent-resistant membranes, and SCD1 is enriched on the lipid raft by HCV infection. Therein, SCD1 supports NS4B-mediated membrane rearrangement to provide a suitable microenvironment for HCV replication. We demonstrated that either genetic or chemical knockdown of SCD1 abrogated HCV replication in both replicon cells and HCV-infected cells. These findings provide novel mechanistic insights into the roles of SCD1 in HCV replication.</P>

Aerobic biotransformation of the antibiotic ciprofloxacin by <i>Bradyrhizobium</i> sp. isolated from activated sludge

Nguyen, Luong N.,Nghiem, Long D.,Oh, Seungdae Elsevier 2018 CHEMOSPHERE - Vol.211 No.-

<P><B>Abstract</B></P> <P>Ciprofloxacin (CIP) is an antibiotic that is widely used to treat bacterial infections and is poorly biodegraded during wastewater treatment. In this study, a CIP-degrading bacterial strain (GLC_01) was successfully retrieved from activated sludge by enrichment and isolation. The obtained bacterial strain shares over 99% nucleotide identity of the 16S rRNA gene with <I>Bradyrhizobium</I> spp. Results show that <I>Bradyrhizobium</I> sp. GLC_01 degraded CIP via cometabolism with another carbon substrate following a first-order kinetics degradation reaction. CIP degradation by <I>Bradyrhizobium</I> sp. GLC_01 increased when the concentration of the primary carbon source increased. The biodegradability of the primary carbon source also affected CIP degradation. The use of glucose and sodium acetate (i.e. readily biodegradable), respectively, as a primary carbon source enhanced CIP biotransformation, compared to starch (i.e. relatively slowly biodegradable). CIP degradation decreased with the increase of the initial CIP concentration. Over 70% CIP biotransformation was achieved at 0.05 mg L<SUP>−1</SUP> whereas CIP degradation decreased to 26% at 10 mg L<SUP>−1</SUP>. The phylogenetic identification and experimental verification of this CIP-degrading bacterium can lead to a bioengineering approach to manage antibiotics and possibly other persistent organic contaminants during wastewater treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Bradyrhizobium</I> sp. GLC_01 was isolated from activated sludge. </LI> <LI> GLC_01 removed CIP via cometabolism with primary carbon source. </LI> <LI> High concentration of the primary carbon source induced better removal of CIP. </LI> <LI> The primary carbon source degradability affected CIP removal. </LI> <LI> GLC_01 could remove 70% of CIP at environmentally relevant concentration. </LI> </UL> </P>

On a Riesz-Feller space fractional backward diffusion problem with a nonlinear source

Tuan, N.H.,Hai, D.N.D.,Long, L.D.,Nguyen, V.T.,Kirane, M. Koninklijke Vlaamse Ingenieursvereniging ; Elsevie 2017 Journal of computational and applied mathematics Vol.312 No.-

<P>In this paper, a backward diffusion problem for a space-fractional diffusion equation with a nonlinear source in a strip is investigated. This problem is obtained from the classical diffusion equation by replacing the second-order space derivative with a Riesz-Feller derivative of order alpha is an element of (0, 2]. A nonlinear problem is severely ill -posed, therefore we propose two new modified regularization solutions to solve it. We further show that the approximated problems are well-posed and their solutions converge if the original problem has a classical solution. In addition, the convergence estimates are presented under a priori bounded assumption of the exact solution. For estimating the error of the proposed method, a numerical example has been implemented. (C) 2016 Elsevier B.V. All rights reserved.</P>

Ecap-less 800V On-board Battery Charger Based on Unbalanced Half-bridge Split Capacitors Power Decoupling Circuit

Tuyen D. Nguyen,Long Nguyen,Dong Tran,Ravi Nath Tripathi,Hai N. Tran 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper proposed an Electrolytic Capacitorless (Ecap-less) 800V onboard charger (OBC) based on a Half-bridge Split Capacitors Power Decoupling (HSC-PD) circuit. A new design and control method proposed for HSCPD to minimize the capacitance needed for the dc-link of the OBC enables the deployment of Film capacitors (Fcap) only. Both dc component and capacitance values of the decoupling capacitors are designed unequally with the bottom-bias capacitor approach, reducing not only equivalent capacitance and ac voltage ripple but the current rating of the PD circuit. An effect of fourth-line frequency harmonics caused by the double-line frequency of voltage and current in the PD circuit is also analyzed. The feedback control developed for HSC-PD based OBC system considering the proposed unequal dc component and capacitance. The impact of the DC offset ratio discussed for the converter efficiency and experimental results demonstrate the superiority of the proposed method.

Effect of thermolysis condition on characteristics and nonsteroidal anti-inflammatory drugs (NSAIDs) absorbability of Fe-MIL-88B-derived mesoporous carbons

Van Tran, Thuan,Nguyen, Duyen Thi Cam,Le, Hanh T.N.,Bach, Long Giang,Vo, Dai-Viet N.,Dao, To-Uyen T.,Lim, Kwon Taek,Nguyen, Trinh Duy Elsevier 2019 Journal of environmental chemical engineering Vol.7 No.5

<P><B>Abstract</B></P> <P>Discharge of nonsteroidal anti-inflammatory drugs (NSAIDs) from wastewater has been increasingly alarmed, led to the advent of the treatment techniques. Among these methods, adsorption is regarded as a tunable and green approach with the utilization of mesoporous carbon (MC) as an efficient and recyclable adsorbent. Herein, we described the strategy for the synthesis of novel MC from Fe-MIL-88B as a self-sacrificial template. Three thermolysis temperatures (550, 750, and 950 °C) were investigated to compare the structural characteristics and absorbability towards selected NSAIDs compounds including diclofenac sodium (DCF), aspirin (APR), and ibuprofen (IBU). Effect of contact time (0–480 min), concentration (10–40 mg/L), pH (2–10), and MC dosage (0.1–0.5 g/L) was systematically studied. Kinetic and isotherm models were also used to find out the adsorption mechanism and behavior of NSAIDs pharmaceutical over MC materials. Proposed mechanism and recyclability test were rigorously studied to gain more insight into how the NSAIDs molecules adsorb on the MC materials and their potential towards drug treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of thermolysis temperature on characteristics and absorbability towards anti-inflammatory drugs was conducted. </LI> <LI> Kinetic, isotherm, and recyclability experiments were systematically studied. </LI> <LI> Adsorption mechanisms including H-bond, π–π interaction, metal–oxygen bridging, and electrostatic attraction were rigorously proposed. </LI> <LI> Outstanding adsorption capacity (∼144 mg/g), and excellent reusability were monitored with Fe-MIL-88B-derived mesoporous carbon. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>