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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.
A Graphical Method to Estimate Forming Limit Curve of Sheet Metals
Pham, Quoc Tuan,Nguyen, Duc Toan,Kim, Jin Jae,Kim, Young Suk Trans Tech Publications, Ltd. 2019 Key Engineering Materials Vol.794 No.-
<P>Since its foundation, the concept of forming limit diagram has been widely accepted in sheet metal forming community as a powerful tool for studying formability. There are pyramid models that were developed to estimate the forming limit curve theoretically, for example, Swift's diffuse necking criterion, Hill's localized necking criterion, Marciniak and Kuczynski model, Modified Maximum Force Criterion, <I>etc</I>.. Implement of these models, however, is a laborious task. To simply the task, this study presents a graphical method to estimate forming limit curve of sheet metal. Some new insights into the Modified Maximum Force Criterion, the Hora method, are discussed. The insights pertain to the use of a graphic tool to estimate limit strains at three critical forming modes in sheet metal forming that are the uniaxial tension, plane strain, and equi-biaxial tension. Connecting three points by linear lines yields to a simple graph of forming limit curve. Method validation is supported by comparing the estimated forming limit curve with experimentally measured data for several automotive sheet metals.</P>
Cost-effective synchronization strategy for distributed generators in islanded microgrids
Pham, Minh-Duc,Hoang, Van-Tuan,Lee, Hong-Hee The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3
A microgrid (MG) is an effective way to integrate various distributed generators (DGs) into a power distribution system. The synchronization of DG voltage with MG voltage is indispensable to prevent inrush currents before connection to a MG system and for working in parallel with other DGs in the MG. In the past, synchronization in terms of both phase and magnitude was realized using additional voltage sensors to measure the MG voltage. However, this increased the system cost. In this paper, a cost-effective synchronization strategy is proposed to allow a DG to connect with an islanded MG system without any additional voltage sensors. The feasibility and effectiveness of the proposed strategy were validated by experiment with a scaled-down islanded microgrid.
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>
Alpha-Glucosidase Inhibitory Activity of Saponins Isolated from Vernonia gratiosa Hance
Cong Pham Van,Anh Hoang Le Tuan,Vinh Le Ba,Han Yoo Kyong,Trung Nguyen Quang,Minh Bui Quang,Duc Ngo Viet,Ngoc Tran Minh,Hien Nguyen Thi Thu,Manh Hoang Duc,Lien Le Thi,Lee Ki Yong 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6
Species belonging to the Vernonia (Asteraceae), the largest genus in the tribe Vernonieae (consisting of about 1,000 species), are widely used in food and medicine. These plants are rich sources of bioactive sesquiterpene lactones and steroid saponins, likely including many as yet undiscovered chemical components. A phytochemical investigation resulted in the separation of three new stigmastane-type steroidal saponins (1 – 3), designated as vernogratiosides A–C, from whole plants of V. gratiosa. Their structures were elucidated based on infrared spectroscopy (IR), one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and electronic circular dichroism analyses (ECD), as well as chemical reactivity. Molecular docking analysis of representative saponins with αglucosidase inhibitory activity was performed. Additionally, the intended substances were tested for their ability to inhibit α-glucosidase activity in a laboratory setting. The results suggested that stigmastane-type steroidal saponins from V. gratiosa are promising candidate antidiabetic agents.
Nguyen Duc Anh,Pham Van Thanh,Doan Tu Lap,Nguyen Tuan Khai,Tran Van An,Tran Duc Tan,Nguyen Huu An,Dang Nhu Dinh 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.2
Forest fires inflict great losses of human lives and serious damages to ecological systems. Hence, numerous fire detection methods have been proposed, one of which is fire detection based on sensors. However, these methods reveal several limitations when applied in large spaces like forests such as high cost, high level of false alarm, limited battery capacity, and other problems. In this research, we propose a novel forest fire detection method based on image processing and correlation coefficient. Firstly, two fire detection conditions are applied in RGB color space to distinguish between fire pixels and the background. Secondly, the image is converted from RGB to YCbCr color space with two fire detection conditions being applied in this color space. Finally, the correlation coefficient is used to distinguish between fires and objects with fire-like colors. Our proposed algorithm is tested and evaluated on eleven fire and non-fire videos collected from the internet and achieves up to 95.87% and 97.89% of F-score and accuracy respectively in performance evaluation.
Trong Duc Tran,Suwicha Kasemsuwan,Manakorn Sukmak,Waraphon Phimpraphai,Tippawon Prarakamawongsa,Long Thanh Pham,Tuyet Bach Hoang,Phuong Thi Nguyen,Thang Minh Nguyen,Minh Van Truong,Tuan Pham Dao,Pawin The Korean Society of Veterinary Science 2024 Journal of Veterinary Science Vol.25 No.1
Background: Avian influenza (AI) is a contagious disease that causes illness and death in poultry and humans. High pathogenicity AI (HPAI) H5N6 outbreaks commonly occur in Quang Ninh province bordering China. In June 2021, the first HPAI H5N8 outbreak occurred at a Quang Ninh chicken farm. Objectives: This study examined the risk factors associated with HPAI H5N6 and H5N8 outbreaks in Quang Ninh. Methods: A retrospective case-control study was conducted in Quang Ninh from Nov 2021 to Jan 2022. The cases were households with susceptible poultry with two or more clinical signs and tested positive by real-time reverse transcription polymerase chain reaction. The controls were households in the same village as the cases but did not show clinical symptoms of the disease. Logistic regression models were constructed to assess the risk factors associated with HPAI outbreaks at the household level. Results: There were 38 cases with H5N6 clade 2.3.4.4h viruses (n = 35) and H5N8 clade 2.3.4.4b viruses (n = 3). Compared to the 112 controls, raising poultry in uncovered or partially covered ponds (odds ratio [OR], 7.52; 95% confidence interval [CI], 1.44-39.27), poultry traders visiting the farm (OR, 8.66; 95% CI, 2.7-27.69), farms with 50-2,000 birds (OR, 3.00; 95% CI, 1.06-8-51), and farms with ≥ 2,000 birds (OR, 11.35; 95% CI, 3.07-41.94) were significantly associated with HPAI outbreaks. Conclusions: Combining biosecurity measures, such as restricting visitor entry and vaccination in farms with more than 50 birds, can enhance the control and prevention of HPAI in Quang Ninh and its spread across borders.
Trong Duc Tran,Suwicha Kasemsuwan,Manakorn Sukmak,Waraphon Phimpraphai,Tippawon Prarakamawongsa,Long Thanh Pham,Tuyet Bach Hoang,Phuong Thi Nguyen,Thang Minh Nguyen,Minh Van Truong,Tuan Pham Dao,Pawin 대한수의학회 2024 Journal of Veterinary Science Vol.25 No.2
Background: Avian influenza (AI) is a contagious disease that causes illness and death in poultry and humans. High pathogenicity AI (HPAI) H5N6 outbreaks commonly occur in Quang Ninh province bordering China. In June 2021, the first HPAI H5N8 outbreak occurred at a Quang Ninh chicken farm. Objectives: This study examined the risk factors associated with HPAI H5N6 and H5N8 outbreaks in Quang Ninh. Methods: A retrospective case-control study was conducted in Quang Ninh from Nov 2021 to Jan 2022. The cases were households with susceptible poultry with two or more clinical signs and tested positive by real-time reverse transcription polymerase chain reaction. The controls were households in the same village as the cases but did not show clinical symptoms of the disease. Logistic regression models were constructed to assess the risk factors associated with HPAI outbreaks at the household level. Results: There were 38 cases with H5N6 clade 2.3.4.4h viruses (n = 35) and H5N8 clade 2.3.4.4b viruses (n = 3). Compared to the 112 controls, raising poultry in uncovered or partially covered ponds (odds ratio [OR], 7.52; 95% confidence interval [CI], 1.44–39.27), poultry traders visiting the farm (OR, 8.66; 95% CI, 2.7–27.69), farms with 50–2,000 birds (OR, 3.00; 95% CI, 1.06–8-51), and farms with ≥ 2,000 birds (OR, 11.35; 95% CI, 3.07–41.94) were significantly associated with HPAI outbreaks. Conclusions: Combining biosecurity measures, such as restricting visitor entry and vaccination in farms with more than 50 birds, can enhance the control and prevention of HPAI in Quang Ninh and its spread across borders.