Adaptive hierarchical sliding mode control using an artificial neural network for a ballbot system with uncertainties

Hai Le Xuan,Quoc-Dong Hoang,Soon Geul Lee,Dat Pham Xuan,Hoang Tran Viet,Minh Pham Van,Hung Pham Van,Hung Pham Viet,PHAM DUC TUAN,Duc Anh Nguyen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

Ballbots, which have been studied for over ten years, are under-actuated mobile robots that operate using the inverted pendulum paradigm. Controlling a ballbot poses a number of challenges, including maintaining the stable upright posture from the ground in all directions and making sure it follows the desired trajectory. External factors such as a minor change in contact surface properties or fabrication errors can affect the system's stabilization and transfer capabilities. In this study, an adaptive hierarchical sliding mode control algorithm based on an artificial neural network is developed to make the ballbot robust to external factors. The use of the proposed controller ensures system stability despite uncertainties including friction, accidental centrifugal forces and gravity that occur when the ballbot follows the reference trajectory. The system stability is guaranteed on the basis of Lyapunov theory. Control efficiency and robot stability under system uncertainties are demonstrated by numerical simulation.

Antimicrobial Constituents from the Bacillus megaterium LC Isolated from Marine Sponge Haliclona oculata

Pham Viet Cuong,Nguyen Thi Kim Cuc,Vu Thi Quyen,Pham Thanh Binh,Phan Van Kiem,Nguyen Hoai Nam,Nguyen Tien Dat 한국생약학회 2014 Natural Product Sciences Vol.20 No.3

Three compounds including 7,7-bis(3-indolyl)-p-cresol (1), cyclo-(S-Pro-R-Leu) (2) and cyclo-(S-Pro-R-Val) (3) were isolated from the strain of Bacillus megaterium LC derived from the marine sponge Haliclona oculata. All the isolated compounds showed antimicrobial activity at MIC values ranging from 0.005 to 5 ?g/mL against Gram-negative bacteria Vibrio vulnificus and V. parahaemolyticus, gram-positive bacteria Bacillus cereus and Micrococcus luteus, and the dermatophyte Trichophyton mentagrophytes. The results suggested that these compounds might have potential to be developed as agents treating dermatosis and controlling vibriosis in aquaculture.

An investigation of performance and emission characteristic of a small marine engine running on heated coconut oil and diesel oil

Van Vang Le,Anh Tuan Hoang,Xuan Duong Pham,Van Viet Pham 국제이네비해양경제학회 2018 International Journal of e-Navigation and Maritime Vol.9 No.1

In recent years, much interest has been devoted to bio-fuels because of their beneficial effects on environment, agriculture and economic development. Raw vegetable oil – a kind of bio-fuels, still exits many downsides, is potential renewable fuel replaced for ever-exhausted fossil fuel. In this report, vegetable oil which is available in the South of Vietnam such as raw coconut oil is studied by heating up different temperature with the aim at decreasing its high viscosity and density and meeting the fuel requirements. The experiments are conducted on heated coconut oil (HCO) and fossil diesel oil (DO) using an 80hp of small marine diesel engine. The results of engine performance as using DO and HCO included engine power (Ne), specific fuel consumption (SFC), thermal efficiency (TE), emission characteristics such as carbon monoxide (CO), unburned hydrocarbon (HC), smoke, nitrogen oxides (NOx) at internal feature are measured. The experiment results show higher SFC, CO, HC and smoke emissions, and lower TE, and NOx emissions for HCO with respect to DO. In addition, this study also reveals that, 1000C of HCO is said to be the most suitable heating temperature as getting the engine performance equals to DO.

Critical Success Factors of Project Management : The Case of Construction Related Projects in Vietnam

Viet Quoc PHAM,Bao Khac Quoc NGUYEN,Binh Van TU,Huong Thi Thanh PHAM,Thanh Quoc LE 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.2

The study aims to contribute to the improvement of project management in Vietnam. It focuses on developing new critical success factors (CSFs) which can be used to assess the success of project management in the country. This is a promising issue considering the rapid changes occurring within the business environment. The reason is because CSFs carry great consequences on project management issues, particularly in the context of Vietnam, which is currently experiencing many big scale projects involving both local and foreign investors. Two applications are utilised. One is to adapt the business model of Belassi and Tukel (1996) to observe the transitional and emerging economy of Vietnam. The other is to examine the data collected from a survey to examine the new CSFs which can then be used to assess the success of its projects and project management in Vietnam. The research results showed some remarkable differences between CSFs of Vietnam and foreign countries in both number of success factors and its impact levels which should be paid attention by foreign project managers/owners when doing investment and project management in Vietnam. The outcome generated can be useful to project owners/managers as well as policy makers in Vietnam’s business environment.

Citrus diaspidids in Viet Nam: New, and confirmation of previous, records based on morphological and molecular verification of taxa

Hang T. Dao,George A.C. Beattie,Gillian W. Watson,Van Lam Pham,Van Liem Nguyen,Duc Khanh Le,Thi Hoa Nguyen,Viet Nguyen,Paul Holford 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Armoured scales (Hemiptera: Diaspididae) belong to the largest scale insect family and are among the mostinvasive insects in the world. Accurate identification of armoured scales is essential for systematic and phylogeneticstudies; biogeography; trade and plant quarantine; and pest management, particularly biological control. Several species are serious pests of citrus. Records of past field surveys conducted in Viet Nam between 1967 and2010 indicated the presence of 28 species on citrus there. Discrepancies in these records, and the retention ofspecimens of only five species in collections, led us to undertake surveys throughout the citrus-growing regionsof the country in 2013 and 2014 to verify previous records and conserve voucher specimens. The presence of 21diaspidid species was confirmed based on morphological and molecular data. The species observed werecommon but rarely abundant. Populations in commercial orchards may have been influenced by use of pesticides,but most species were recorded also in gardens and orchards where pesticide use was uncommon. Naturalenemies were abundant, but were not thoroughly documented for all the diaspidids we observed. An identificationkey to the species collected is provided. Differences between our findings and previous records from VietNam, from Yunnan and Guangxi in China, and from Indochinese countries neighbouring Viet Nam, indicate theneed for extensive surveys to fully document the diaspidid fauna on citrus in the region.

Influence of Credit on the Income of Households Borrowing from Banks: Evidence from Vietnam Bank for Agriculture and Rural Development, Kien Giang Province

Quang Vang DANG(Quang Vang DANG ),Viet Thanh Truc TRAN(Viet Thanh Truc TRAN ),Hieu PHAM(Hieu PHAM ),Van Nam MAI(Van Nam MAI ),Quoc Duy VUONG(Quoc Duy VUONG ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2

This paper investigates the determinants of credit accessibility and the effect of credit on the income of farm households borrowing from Vietnam Bank for Agriculture and Rural Development, Giong Rieng District Branch, Kien Giang Province. Based on the primary data of 200 farming households who are the customer of the bank, the study applied the Probit regression model to examine determinant factors of credit accessibility of farm households and employed the Propensity score matching method to investigate the impact of credit on households’ income. The findings of the Probit regression shown that three independent variables that significantly influence the access to credit of households are household size, income source, and farm size. Besides that, the Propensity score matching method results showed a difference of 23.799 million VND/year between the income of borrowing households and that of non-borrowing households at the significance level of 1%. The difference in the imcome from the interval and central matching methods are VND 24.700 million VND/year and VND 24.633 million VND/year, respectively. Given empirical findings suggetsted that several recommendations to increase the credit accessibility of farm households, thereby creating favorable conditions for improving their income.

A DTC Stator Flux Algorithm for the Performance Improvement of Induction Traction Motors

Van-Tien, Pham,Zheng, Trillion Q.,Yang, Zhong-ping,Lin, Fei,Do, Viet-dung The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

In view of the speed control characteristics of induction traction motors and the problems of direct torque control (DTC) algorithms in current applications, this paper presents a DTC algorithm characterized by a symmetrical polygon flux control and a closed loop power control in the constant-torque base speed region and constant-power field-weakening region of induction traction motors. This algorithm only needs to add a stator flux control algorithm to the traditional DTC structures. This has the benefit of simplicity, while maintaining the features of traditional algorithms such as a rapid dynamic response, uncomplicated control circuit, reduced dependence on motor parameters, etc. In addition, it obtains a smoother flux trajectory that is conducive to improvement of the harmonic elimination capability, the switching frequency utilization as well as the torque and power performance in the field-weakening region. The effectiveness and feasibility of this DTC algorithm are demonstrated by both theoretical analysis and experimental results.

A DTC Stator Flux Algorithm for the Performance Improvement of Induction Traction Motors

Pham Van-Tien,Trillion Q. Zheng,Zhong-ping Yang,Fei Lin,Viet-dung Do 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

In view of the speed control characteristics of induction traction motors and the problems of direct torque control (DTC) algorithms in current applications, this paper presents a DTC algorithm characterized by a symmetrical polygon flux control and a closed loop power control in the constant-torque base speed region and constant-power field-weakening region of induction traction motors. This algorithm only needs to add a stator flux control algorithm to the traditional DTC structures. This has the benefit of simplicity, while maintaining the features of traditional algorithms such as a rapid dynamic response, uncomplicated control circuit, reduced dependence on motor parameters, etc. In addition, it obtains a smoother flux trajectory that is conducive to improvement of the harmonic elimination capability, the switching frequency utilization as well as the torque and power performance in the field-weakening region. The effectiveness and feasibility of this DTC algorithm are demonstrated by both theoretical analysis and experimental results.

Additive biocomponents from catfish by-products enhance the growth of shrimp Litopenaeus vannamei

Pham Viet Nam,Tran Vy Hich,Nguyen Van Hoa,Khuong V. Dinh,Nguyen Cong Minh,Trang Si Trung 한국수산과학회 2023 Fisheries and Aquatic Sciences Vol.26 No.6

The rapid expansion of shrimp production requires a huge amount of protein sources from soybeans and wild-caught fishmeal; both are becoming a shortage. Meanwhile, catfish production and processing is a giant industry in Vietnam, which produce hundred thousand tonnes of protein- and lipid-rich by-products, annually. Using catfish by-products to gradually replace the traditional protein sources in shrimp aquaculture may bring triple benefits: 1) reducing pressure on wild fish exploitation for fishmeal, 2) reducing the environmental impacts of catfish by-products, and 3) increasing the value and sustainability of aquaculture production. In this study, we used catfish by-products to produce fish protein hydrolysate (FPH) and nano-hydroxyapatite (HA) as additives in feed for Pacific white shrimp (Litopenaeus vannamei). The supplement mixture of FPH and HA was added into the commercial diet (Charoen Pokphand Group [CP], 38% protein, and 6.5% lipid) to reach 38%, 38.5%, 40%, 43%, and 44% of the crude protein content. The survival and growth of shrimps were weekly assessed to day 55. The results showed that the shrimp growth was highest at 43% crude protein content in the feed as indicated by an increase of 124% and 112% in shrimp weight and length, respectively, compared to the commercial reference diet. No negative effects of adding the mixture of FPH and HA on the water quality were observed. Vibrio density was lower than 6.5 × 103 CFU/mL, which is the lowest Vibrio density negatively affecting the shrimp growth and development. These findings indicate that the mixture of FPH and HA are promising additive components in feed for post-larval shrimp L. vannamei diets.

Quantitative electrophysiological monitoring of anti–histamine drug effects on live cells <i>via</i> reusable sensor platforms

Pham Ba, Viet Anh,Cho, Dong-guk,Kim, Daesan,Yoo, Haneul,Ta, Van-Thao,Hong, Seunghun Elsevier 2017 Biosensors & bioelectronics Vol.94 No.-

<P><B>Abstract</B></P> <P>We demonstrated the quantitative electrophysiological monitoring of histamine and anti–histamine drug effects on live cells <I>via</I> reusable sensor platforms based on carbon nanotube transistors. This method enabled us to monitor the real–time electrophysiological responses of a single HeLa cell to histamine with different concentrations. The measured electrophysiological responses were attributed to the activity of histamine type 1 receptors on a HeLa cell membrane by histamine. Furthermore, the effects of anti–histamine drugs such as cetirizine or chlorphenamine on the electrophysiological activities of HeLa cells were also evaluated quantitatively. Significantly, we utilized only a single device to monitor the responses of multiple HeLa cells to each drug, which allowed us to quantitatively analyze the antihistamine drug effects on live cells without errors from the device-to-device variation in device characteristics. Such quantitative evaluation capability of our method would promise versatile applications such as drug screening and nanoscale bio sensor researches.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed a reusable sensor platform to monitor the activities of multiple adherent cells with a single-cell-level. </LI> <LI> The reusable sensor platform was used to monitor the electrophysiological responses of individual adherent cells to drugs. </LI> <LI> Using the method, we quantitatively evaluated the effect of histamine and anti–histamine drugs to HeLa cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>