A Novel Bandwidth Estimation Method Based on MACD for DASH

( Van-huy Vu ),( Ibrahim Mashal ),( Tein-yaw Chung ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

Nowadays, Dynamic Adaptive Streaming over HTTP (DASH) has become very popular in streaming multimedia contents. In DASH, a client estimates current network bandwidth and then determines an appropriate video quality with bitrate matching the estimated bandwidth. Thus, estimating accurately the available bandwidth is a significant premise in the quality of video streaming, especially when network traffic fluctuates substantially. To cope with this challenge, researchers have presented various filters to estimate network bandwidth adap-tively. However, experiment results show that current schemes either adapt slowly to net-work changes or adapt fast but are very sensitive to delay jitter and produce sharply changed estimation. This paper presents a novel bandwidth estimation scheme based on Moving Av-erage Convergence Divergence (MACD). We applied an MACD indicator and its two thresholds to classifying network states into stable state and agile state, based on the network state different filters are applied to estimate network bandwidth. In the paper, we studied the performance of various MACD indicators and the threshold values on bandwidth estimation. Then we used a DASH proxy-based environment to compare the performance of the present-ed scheme with current well-known schemes. The simulation results illustrate that the MACD-based bandwidth estimation scheme performs superior to existing schemes both in the speed of adaptively to network changes and in stability in bandwidth estimation.

Online Actor-critic Reinforcement Learning Control for Uncertain Surface Vessel Systems with External Disturbances

Van Tu Vu,Quang Huy Tran,Thanh Loc Pham,Phuong Nam Dao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3

This article addresses a trajectory tracking control approach for an uncertain surface vessel using the new cascade structure of adaptive reinforcement learning (ARL) algorithm and kinematic controller, feed-forward term. Since a surface vessel is decoupled by kinematic sub-system and dynamic sub-system, the cascade control system is an ideal method for obtaining the tracking problem. In the proposed control structure, the dynamic control loop is designed to be the optimized method of the corresponding dynamic sub-system and the kinematic control loop is implemented by a nonlinear controller combining with feed-forward term. The online actor-critic architecture is considered in ARL algorithm to overcome the challenge of solving the Hamilton-Jacobi-Bellman (HJB) equation. Additionally, the proposed controller is able to handle the difficulty of the non-autonomous optimal control problem by designing the ARL technique for the corresponding system with a small number of state variables. Based on theoretical analysis, the ARL based control design has been made to guarantee the uniformly ultimately bounded (UUB) stability of the closed system. Finally, the simulation results are illustrated to verify the effectiveness of the proposed control scheme.

Inspecting the Relationship among E-service Quality, E-trust, E-customer Satisfaction and Behavioral Intentions of Online Shopping Customers

Van-Dat Tran,Quang Huy Vu 사람과세계경영학회 2019 Global Business and Finance Review Vol.24 No.3

The purpose of this study is to clarify whether there are relationships among the four key factors contributing to the success of e-business: e-service quality, e-trust e-customer satisfaction and behavioral intentions, thus make a conclusion and provide better understanding in the field of e-service and e-marketing. This study method used to evaluate and test the scale and theoretical model in the study is quantitative research with sample size N = 476 through the survey to deliver questionnaire directly to subjects. This study examined the scale by confirmatory factor analysis (CFA) and the model of theoretical research by structural equation modeling (SEM). The results of analysis and verification of measurement scales and theoretical research models show that the research scales achieve unidirectional, reliability, convergent validity and high discriminant validity. The hypotheses are accepted at 95% reliability. The study has discovered the new indirect and positive impact of e-service quality on behavioral intentions through mediators e-trust and e-customer satisfaction, as well as other sub relationships, which can be used as foundation for future researches. At the end, managerial implications and recommendations plus contributions are proposed for e-commerce firms, e-marketers and researchers.

Micropropagation from root segments to improve seedling quality in Chinese foxglove crops

Thanh Loan Pham,Van Huy Nguyen,Thi Le Thu Hoang,Thi Tam Tien Ha,Trung Kien Tran,Xuan Duong Vu,Phi Bang Cao,Quang Trung Nguyen 한국식물생명공학회 2020 JOURNAL OF PLANT BIOTECHNOLOGY Vol.47 No.3

This is the first study to establish a complete protocol for micropropagation of Rehmannia glutinosa from root segments. The study involved investigating the effect of plant growth regulators on in vitro shoot regeneration and rooting and identifying substrates supporting survival and growth performance of ex vitro seedlings. A Murashige and Skoog (MS) medium containing 30 g/L sucrose for shoot induction and 0.2 mg/L indole-3-acetic acid (IAA), 1 mg/L 6-benzylaminopurine (BAP), and 1 g/L polyvinylpyrrolidone (PVP) for shoot multiplication resulted in the highest number of shoots per explant and shoot height. Applying a medium containing 0.5 mg/L IAA and 1 g/L PVP yielded optimal rooting of the shoots grown in vitro. Compost enriched with microbial inoculants and perlite enhanced seedling growth better than that with organic biofertilizer-free substrates (soil and sand). We recommend the continuous production of micropropagated R. glutinosa seedlings from root segments under the aforementioned conditions as a possible propagation technique for crops of this species.

Photocatalytic removal of Rhodamine B in water using g-C3N4/MIL-53(Fe) material under LED visible light with persulfate activation

Nguyen Trung Dung,Nguyen Van Hiep,Manh B. Nguyen,Vu Dinh Thao,Nguyen Nhat Huy 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10

Photocatalysis is usually considered as one of the most effective methods for treating non-biodegradable pollutants commonly found in textile wastewater. In this study, the photocatalyst of g-C3N4/MIL-53(Fe) was synthesized by the hydrothermal method and applied for the removal of Rhodamine B (RhB) in water. The photocatalytic material was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller analysis, UV-Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the g-C3N4 doped MIL-53(Fe) with 97 wt% of MIL- 53(Fe) works effectively under visible light and the presence of oxidants (Na2S2O8). RhB removal efficiency can be more than 99% with 20mg/L of RhB, 300mg/L of catalyst, 200mg/L of Na2S2O8, and pH 3. In addition, the photocatalytic degradation mechanism of RhB with g-C3N4/MIL-53(Fe) was also proposed, which could be improved and studied for a wide range of applications in textile wastewater treatment.

Homogeneous Disturbance Observer Based on Sliding Mode Observer and Controller for T-Type Inverter

Do Tuan Anh,Pham Quoc Huy,Giap Van Nam,Nguyen Quang Dich,Vu Phuong 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

This paper proposes a novel sliding mode control (SMC) for the T-Type inverter in the standalone mode. Firstly, the accuracy of the estimated states used to construct the fxed-time SMC and the disturbance observer (DOB) is improved by a proposed sliding mode observer (SMO). Secondly, a DOB is designed without the requirement of the frst derivative or the format of the disturbance. Thirdly, an advanced reaching law is utilized for both the SMO, the DOB, and the SMC controller for the chattering elimination. Fourth, the stability of the proposed controller is confrmed by the Lyapunov condition. The performance of the proposed control strategy is validated by simulations and experiments with the same scenarios of nonlinear load and parameter variations. The results prove that the output voltage of the proposed control method meets the standard EN 62040 with the total harmonic distortion being lower than 5% in all cases, which is superior to the performance of the traditional controller.

An Adsorptive Membrane Based on Electrospun Graphene Oxide/Poly(vinylidene) Fluoride Fiber Coated with Chitosan for Removal of Manganese Ions from Aqueous Solutions Using a Simple Filtration Process

Le Thi Le,Phan Ngoc Vu,Huu The Nguyen,Manh Van Nguyen,Hieu Trung Bui,Huy Quang Tran,Thuy Thi Thu Nguyen 한국섬유공학회 2023 Fibers and polymers Vol.24 No.9

The goal of this study was to develop an adsorptive membrane based on electrospun graphene oxide/poly(vinylidene) fluoride fiber mat coated with chitosan (GO-PVDF/CS composite membrane) which can potentially be used to remove Mn2+ from aqueous solutions by a continuous filtration process. This composite membrane was composed of two layers: the first layer was the electrospun PVDF fiber mat containing GO, supporting mechanical strength, improving hydrophilicity, and providing adsorptive sites; the second layer was a thin CS film coated on top of the first layer with the aim of significantly enhancing hydrophilicity and adsorption capacity of the composite membrane. The hydrophilicity and porosity of the GO-PVDF/CS composite membrane depended on the concentration of the CS solution, subsequently affecting the Mn2+ removal efficiency of the membrane. The GO-PVDF/CS membrane achieved the maximum Mn2+ removal efficiency of 90.7 wt% by a continuous flow filtration process with a flux of 157.3 L.m-2.h-1.bar-1. The GO-PVDF/CS membrane was able to decrease the concentration of Mn2+ from 5.72 to 0.38 mg/L in the groundwater-contaminated Mn2+ after two filtration processes, reaching the notification level of Mn2+ for drinking water that was allowed by several countries. Therefore, the GO-PVDF/CS membrane can be an effective adsorptive filtration membrane used to remove Mn2+ from groundwater.

Physiological intracytoplasmic sperm injection does not improve the quality of embryos: A cross-sectional investigation on sibling oocytes

Minh Tam Le,Hiep Tuyet Thi Nguyen,Trung Van Nguyen,Thai Thanh Thi Nguyen,Hong Nhan Thi Dang,Thuan Cong Dang,Quoc Huy Vu Nguyen The Korean Society for Reproductive Medicine 2023 Clinical and Experimental Reproductive Medicine Vol.50 No.2

Objective: This study aimed to compare the efficacy of physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic sperm injection (ICSI) in terms of the fertilization rate and embryo quality using sibling oocyte cycles. Methods: This prospective, cross-sectional study collected data from 76 couples who underwent their first cycle at the Hue Center for Reproductive Endocrinology and Infertility, Vietnam, between May 2019 and November 2021. The inclusion criteria were cycles with at least eight oocytes and a sperm concentration of 5×10⁶/mL. Sperm parameters, sperm DNA fragmentation (SDF), fertilization, and the quality of cleavage-stage embryos on day 2 and blastocysts on day 5 were examined. Results: From 76 ICSI cycles, 1,196 metaphase II (MII) oocytes were retrieved, half of which were randomly allocated to either the PICSI (n=592) or ICSI (n=604) treatment group. The results showed no significant difference between the two groups in terms of fertilization (72.80% vs. 75.33%, p=0.32), day 2 cleavage rate (95.13% vs. 96.04%, p=0.51), blastulation rate (52.68% vs. 57.89%), and high-quality blastocyst rate (26.10% vs. 31.13%, p=0.13). However, in cases where SDF was low, 59 cycles consisting of 913 MII oocytes produced a considerably higher blastulation rate with PICSI than with ICSI (50.49% vs. 35.65%, p=0.00). There were no significant differences between the pregnancy outcomes of the PICSI and ICSI embryo groups following embryo transfer. Conclusion: Using variable sperm quality provided no benefit for PICSI versus ICSI in terms of embryo outcomes. When SDF is low, PICSI appears to be able to produce more blastocysts.

Appropriation of Protocol for Laparoscopic Pancreaticoduodenectomy in Treatment of Periampullary Cancer

( Minh Hai Pham ),( Quan Anh Tuan Le ),( Hoang Bac Nguyen ),( Quang Hung Vu ),( Thai Ngoc Huy Tran ),( Hang Dang Khoa N Guyen ),( Thi Ngoc Sang Duong ),( Van Toan Tran ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Laparoscopic pancreaticoduodenectomy (LPD) is considered as a safe and effective procedure in well - selected patients and appropriate surgical technique. Our aim is to evaluate suitability of using protocol for LPD in treatment of periampullary cancer at a single team. Methods: case series Results: Indication for LPD included 37 cases with resectable tumors which were classified basing on NCCN. All witness evaluation risk of complications with PREPARE score, ASA and evaluation risk of postoperative pancreatic fistula (POPF) with FRS classification. There were 2 open conversions because of vein resections, accounting for 5.4%. Standard lymphadenectomy was performed in all of 37 cases. In term of PREPARE score, major complications (Clavien - Dindo >= III) were 17.8%, 0% and 0% (5/28, 0/5 and 0/2 cases) in low risk, intermediate risk and high risk group, respectively. All of cases had ASA I or II. POPF happened 11.1% (1/9), 4.1% (1/24) and 50% (1/2) in low risk, intermediate risk and high risk group, respectively. Frozen section was needed for R0 margin. Retrieved lymph nodes was 8 - 18 with 12 lymph nodes in average. Conclusions: Indication for LPD with resectable tumors is acceptable. ASA I or II is a safe measure to select patient for LPD. FRS classification shows appropriation to evaluate risk of POPF.

Thinning and drilling laser-assisted hatching in thawed embryo transfer: A randomized controlled trial

Le, Minh Tam,Nguyen, Thi Tam An,Nguyen, Thi Thai Thanh,Nguyen, Van Trung,Le, Dinh Duong,Nguyen, Vu Quoc Huy,Cao, Ngoc Thanh,Aints, Alar,Salumets, Andres The Korean Society for Reproductive Medicine 2018 Clinical and Experimental Reproductive Medicine Vol.45 No.3

Objective: In frozen and thawed embryos, the zona pellucida (ZP) can be damaged due to hardening. Laser-assisted hatching (LAH) of embryos can increase the pregnancy rate. This study compared thinning and drilling of the ZP before frozen embryo transfer (FET). Methods: Patients were randomly allocated into two groups for LAH using thinning or drilling on day 2 after thawing. Twenty-five percent of the ZP circumference and 50% of the ZP thickness was removed in the thinning group, and a hole $40{\mu}m$ in diameter was made in the drilling group. Results: A total of 171 in vitro fertilization/intracytoplasmic sperm injection FET cycles, including 85 cycles with drilling LAH and 86 cycles with thinning LAH, were carried out. The thinning group had a similar ${\beta}$-human chorionic gonadotropin-positive rate (38.4% vs. 29.4%), implantation rate (16.5% vs. 14.4%), clinical pregnancy rate (36.0% vs. 25.9%), miscarriage rate (5.8% vs. 2.4%), ongoing pregnancy rate (30.2% vs. 23.5%), and multiple pregnancy rate (7.0% vs. 10.6%) to the drilling LAH group. There were no significant differences in pregnancy outcomes between subgroups defined based on age (older or younger than 35 years) or ZP thickness (greater or less than $17{\mu}m$) according to the LAH method. Conclusion: The present study demonstrated that partial ZP thinning or drilling resulted in similar outcomes in implantation and pregnancy rates using thawed embryos, irrespective of women's age or ZP thickness.