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.

Impact of EVFTA on Trade Flows of Fruits between Vietnam and the EU

Duc Trong TRAN,Van Thu BUI,Ngoc Minh VU,Tung Son PHAM,Hue Minh TRUONG,Thuy Thu DANG,Tu Van TRINH 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.5

The European Union Vietnam Free Trade Agreement (EVFTA) took effect on August 1 paving the way for increased trade between the EU and Vietnam; this marked a huge turning point for the Vietnamese economy. Agriculture products, especially fruits, must be listed when it comes to Vietnam export industries that profit the most from EVFTA. After a period of study, with the desire to contribute to the improvement in the efficiency of Vietnam’s agricultural products to the EU, the researchers want to assess the impact of the EVFTA on the flows of Vietnamese fruits to the EU market. The study uses a quantitative analysis method via the WITS-SMART model with data on export turnover and tariff reductions in parallel with the analysis of changes in factors affecting the trade flows of fruits between the two markets when the EVFTA takes effect. As a result, Vietnam’s fruit importing from the EU is expected to escalate by 29.18% in 2021, while the flow of export will only inch up by 0.955%, which is rather low compare to the increase in import value. Hence, effective policies must be introduced in Vietnam to innovate production methods and increase product quality, so that the EVFTA can be used to boost Vietnam’s fruit exports to the EU.

Evaluating Load-Carrying Capacity of Short Composite Beam Using Strain-Hardening HPFRC

Duy-Liem Nguyen,Vu-Tu Tran,Ngoc-Thanh Tran,Tri-Thuong Ngo,Manh-Tuan Nguyen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

The main goal of this study was to develop the short composite beams using strain-hardening fiber-reinforced concrete (S_HPFRC) and conventional concrete (CC) together. Firstly, the sensitivity of the hybrid fiber system to the enhancement of mechanical properties of plain high performance concrete (P_mortar) was experimentally studied. The ranking of the mechanical properties in terms of sensitive coefficient was observed as follows: direct tensile > splitting tensile > compressive. Next, the responses of short composite beams with various thicknesses of S_HPFRC were investigated under a three-point bending test (3PBT). Six beams with no reinforcement (type A) and six beams with reinforcement were tested (type B) with their identical dimensions of 150 × 150 × 300 mm (depth × width × span length). The compressive strength of S_HPFRC and CC were about 80.65 MPa and 21.12 MPa, respectively. Most of the composite beams were observed to fail in shear mode. And, there was a favorable effect on enhancing the load-carrying capacity of a beam as S_HPFRC was placed at a critical tensile zone. Finally, based on the test data, the analytical equations were proposed for the purpose of predicting shear resistance of the S_HPFRC - CC beam.

A study of pathological characteristics and BRAF V600E status in Langerhans cell histiocytosis of Vietnamese children

Thu Dang Anh Phan,Bao Gia Phung,Tu Thanh Duong,Vu Anh Hoang,Dat Quoc Ngo,Nguyen Dinh The Trinh,Tung Thanh Tran 대한병리학회 2021 Journal of Pathology and Translational Medicine Vol.55 No.2

Background: Langerhans cell histiocytosis (LCH) is more common in children than adults and involves many organs. In children, the BRAF V600E mutation is associated with recurrent and high-risk LCH. Methods: We collected paraffin blocks of 94 pediatric LCH patients to detect BRAF V600E mutation by sequencing. The relationship between BRAF V600E status and clinicopathological parameters were also critically analyzed. Results: BRAF V600E mutation exon 15 was detected in 45 cases (47.9%). Multiple systems LCH showed a significantly higher BRAF V600E mutation rate than a single system (p = .001). No statistical significance was evident for other clinical characteristics such as age, sex, location, risk organs involvement, and CD1a expression. Conclusions: In Vietnamese LCH children, the proportion of BRAF V600E mutational status was relatively high and related to multiple systems.

Using Online Respondent Driven Sampling for Vietnamese Youths’ Alcohol Use and Associated Risk Factors

Melvyn WB Zhang,Bach Xuan Tran,Huong Lan Thi Nguyen,Huong Thi Le,Nguyen Hoang Long,Huong Thi Le,Nguyen Duc Hinh,Tran Dinh Tho,Bao Nguyen Le,Vu Thi Minh Thuc,Chau Ngo,Nguyen Huu Tu,Carl A. Latkin,Roger 대한의료정보학회 2017 Healthcare Informatics Research Vol.23 No.2

Objectives: The average alcohol consumption per capita among Vietnamese adults has consistently increased. Although alcoholrelated disorders have been extensively studied, there is a paucity of research shedding light on this issue among Internet users. The study aimed to examine the severity of alcohol-related disorders and other associated factors that might predispose individuals towards alcohol usage in a sample of youths recruited online. Methods: An online cross-sectional study was conducted with 1,080 Vietnamese youths. A standardized questionnaire was used. Respondent-driven sampling was applied to recruit participants. Multivariate logistic and Tobit regressions were utilized to identify the associated factors. Results: About 59.5% of the males and 12.7% of the total youths declared that they were actively using alcohol. From the total sample, a cumulative total of 32.3% of the participants were drinking alcohol, with 21.8% and 25.0% of the participants being classified as drinking hazardously and binge drinkers, respectively. The majority of the participants (60.7%) were in the pre-contemplative stage. Conclusions: A high prevalence of hazardous drinking was recognized among online Vietnamese youths. In addition, we found relationships between alcohol use disorder and other addictive disorders, such as tobacco smoking and water-pipe usage. Our results highlighted that the majority of the individuals are not receptive to the idea of changing their alcohol habits, and this would imply that there ought to be more government effort towards the implementation of effective alcohol control policies.

Sleep Quality and Poor Sleep-related Factors Among Healthcare Workers During the COVID-19 Pandemic in Vietnam

Thang Phan,Ha Phan Ai Nguyen,Cao Khoa Dang,Minh Tri Phan,Vu Thanh Nguyen,Van Tuan Le,Binh Thang Tran,Chinh Van Dang,Tinh Huu Ho,Minh Tu Nguyen,Thang Van Dinh,Van Trong Phan,Binh Thai Dang,Huynh Ho Ngo The Korean Society for Preventive Medicine 2023 예방의학회지 Vol.56 No.4

Objectives: The coronavirus disease 2019 (COVID-19) pandemic has increased the workload of healthcare workers (HCWs), impacting their health. This study aimed to assess sleep quality using the Pittsburgh Sleep Quality Index (PSQI) and identify factors associated with poor sleep among HCWs in Vietnam during the COVID-19 pandemic. Methods: In this cross-sectional study, 1000 frontline HCWs were recruited from various healthcare facilities in Vietnam between October 2021 and November 2021. Data were collected using a 3-part self-administered questionnaire, which covered demographics, sleep quality, and factors related to poor sleep. Poor sleep quality was defined as a total PSQI score of 5 or higher. Results: Participants' mean age was 33.20±6.81 years (range, 20.0-61.0), and 63.0% were women. The median work experience was 8.54±6.30 years. Approximately 6.3% had chronic comorbidities, such as hypertension and diabetes mellitus. About 59.5% were directly responsible for patient care and treatment, while 7.1% worked in tracing and sampling. A total of 73.8% reported poor sleep quality. Multivariate logistic regression revealed significant associations between poor sleep quality and the presence of chronic comorbidities (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.17 to 5.24), being a frontline HCW directly involved in patient care and treatment (OR, 1.59; 95% CI, 1.16 to 2.16), increased working hours (OR, 1.84; 95% CI,1.37 to 2.48), and a higher frequency of encountering critically ill and dying patients (OR, 1.42; 95% CI, 1.03 to 1.95). Conclusions: The high prevalence of poor sleep among HCWs in Vietnam during the COVID-19 pandemic was similar to that in other countries. Working conditions should be adjusted to improve sleep quality among this population.