Effects of hydrophobicity and lubricant characteristics on anti-icing performance of slippery lubricant-infused porous surfaces

Nguyen, Thanh-Binh,Park, Seungchul,Jung, Youngdo,Lim, Hyuneui THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2019 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.69 No.-

<P><B>Abstract</B></P> <P>Anti-icing properties were investigated in terms of adhesion force on slippery lubricant-infused porous surfaces with several lubricants. Initial wetting state of substrate and lubricant characteristics were verified in anti-icing performance. Superhydrophobicity of porous substrate under lubricant intervening layer was effective to reduce adhesion force in anti-icing. The relationships between adhesion force and lubricant characteristics including viscosity, density, and surface tension were analyzed but no correlation was found. Interfacial surface tension exhibited a relatively negative correlation with adhesion strength. However, spreading coefficient of liquid–liquid interface was found to be the most important factor in determining lubricant when designing icephobic surfaces.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Anti-icing properties are evaluated by measuring the adhesion force on various SLIPS. </LI> <LI> Initial superhydrophobicity of porous surfaces is important for anti-icing performance. </LI> <LI> Adhesion force is not affected by viscosity, density, and surface tension of lubricants. </LI> <LI> Spreading coefficient of the liquid–liquid interface is the most important factor. </LI> <LI> This study is useful for determining the best lubricant to design icephobic SLIPS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Spreading coefficient is a key factor in selecting the lubricant for anti-icing applications of SLIPS.</P> <P>[DISPLAY OMISSION]</P>

An Adaptive Backstepping Trajectory Tracking Control of a Tractor Trailer Wheeled Mobile Robot

NGUYEN THANH BINH,Nguyen Anh Tung,Dao Phuong Nam,Nguyen Hong Quang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.2

The considered Tractor Trailer Wheeled Mobile Robot (TTWMR) is type of Mobile Robot including amaster robot – Tractor and slave robots – Trailers which moves along Tractor to track a given desired trajectory. Themain difficulties of the stabilization and the tracking control of TTWMR are due to nonlinear and underactuatedsystems subjected to nonholonomic constraints. In order to overcome these problems, firstly, we develop the modelof TTWMR and transform the tracking error model to the triangular form to propose a control law and an adaptivelaw. Secondly, the varying time state feedback controllers are designed to generate actuator torques by usingBackstepping technique and Lyapunov direct’s method, in that these are able to guarantee the stability of the wholesystem including kinematics and dynamics. In addition, the Babarlat’s lemma is used to prove that the proposedtracking errors converge to the origin and the proposed adaptive law is carried on to tackle unknown parameterproblem. The simulations are implemented to demonstrate the effective performances of the proposed adaptive lawand the proposed control law.

Synthesis and High Photocatalytic Activity of Zn-doped TiO₂ Nanoparticles by Sol-gel and Ammonia-Evaporation Method

Nguyen, Thanh Binh,Hwang, Moon-Jin,Ryu, Kwang-Sun Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.1

Photocatalysis has been applied to decompose the waste and toxic materials produced in daily life and in the global environment. Pure $TiO_2$ (Zn-$TiO_2$-0) and Zn-doped $TiO_2$ (Zn-$TiO_2$-x, x = 3-10 mol %) samples were synthesized using a novel sol-gel and ammonia-evaporation method. The Zn-doped $TiO_2$ samples showed high photocatalytic activity for the degradation of methylene blue (MB). The physicochemical properties of the samples were investigated using XRD, SEM, ICP, DLS and BET methods. In addition, the most important measurement of photocatalytic ability was investigated by a UV-vis spectrophotometer. The effects of the mol % of zinc ion doping in $TiO_2$ on photocatalytic activity were studied. Among the mol % Zn ions investigated, the Zn-$TiO_2$-9 sample showed the highest photoreactivity. This sample removed 91.4% of the MB after 4 h, while the pure $TiO_2$ only removed 46.4% of the MB.

Effects of hydrophobicity and lubricant characteristics on anti-icing performance of slippery lubricant-infused porous surfaces

Thanh-Binh Nguyen,박승철,정영도,임현의 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

Anti-icing properties were investigated in terms of adhesion force on slippery lubricant-infused porous surfaces with several lubricants. Initial wetting state of substrate and lubricant characteristics were verified in anti-icing performance. Superhydrophobicity of porous substrate under lubricant intervening layer was effective to reduce adhesion force in anti-icing. The relationships between adhesion force and lubricant characteristics including viscosity, density, and surface tension were analyzed but no correlation was found. Interfacial surface tension exhibited a relatively negative correlation with adhesion strength. However, spreading coefficient of liquid–liquid interface was found to be the most important factor in determining lubricant when designing icephobic surfaces.

Real-time Human Detection under Omni-dir ectional Camera based on CNN with Unified Detection and AGMM for Visual Surveillance

Nguyen, Thanh Binh,Nguyen, Van Tuan,Chung, Sun-Tae,Cho, Seongwon Korea Multimedia Society 2016 멀티미디어학회논문지 Vol.19 No.8

In this paper, we propose a new real-time human detection under omni-directional cameras for visual surveillance purpose, based on CNN with unified detection and AGMM. Compared to CNN-based state-of-the-art object detection methods. YOLO model-based object detection method boasts of very fast object detection, but with less accuracy. The proposed method adapts the unified detecting CNN of YOLO model so as to be intensified by the additional foreground contextual information obtained from pre-stage AGMM. Increased computational time incurred by additional AGMM processing is compensated by speed-up gain obtained from utilizing 2-D input data consisting of grey-level image data and foreground context information instead of 3-D color input data. Through various experiments, it is shown that the proposed method performs better with respect to accuracy and more robust to environment changes than YOLO model-based human detection method, but with the similar processing speeds to that of YOLO model-based one. Thus, it can be successfully employed for embedded surveillance application.

SW Architecture Design for Video Content Analytics in DM8148-based Smart IP Network Camera

Thanh Binh Nguyen,Tae in Seol,Cheng-Guang Quan,Sun-Tae Chung,HoSeok Kang,Seongwon Cho 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.1

DM8148 is a high-performance digital media multi-core SOC processor which supports 4 core CPUs (upto 1GHZ ARM Cortex-A8, dual ARM Cortex-M3, upto 750㎒ C674x DSP) as well as various peripherals s uch a s v ideo input/output interface, Ethernet, USB, Serial, and etc., so that it is popularly adopted for high-performance IPNC(IP network camera). TI designs and provides a software framework, Multi-Channel FrameWork(McFW) for this powerful multi-core DM8148 which supports development of efficient and flexible multi-core real-time processing through links and chains. In this paper, we describe our study for an effective SW architecture design for VCA support using McFW for DM8148-based IPNC. VCA is designed and implemented as a link running on DSP, and video data captured from M3 core is designed to be passed over VCA link through a chain. The exchange of VCA-related information (configuration and command for VCA, and meta data results of VCA processing) between remote clients and the smart IPNC is designed to be compatible with ONVIF standard. Current implementation shows that the design works effectively.

Effects of morphology parameters on anti-icing performance in superhydrophobic surfaces

Nguyen, Thanh-Binh,Park, Seungchul,Lim, Hyuneui Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.435 No.-

<P><B>Abstract</B></P> <P>In this paper, we report the contributions of actual ice–substrate contact area and nanopillar height to passive anti-icing performance in terms of adhesion force and freezing time. Well-textured nanopillars with various parameters were fabricated via colloidal lithography and a dry etching process. The nanostructured quartz surface was coated with low-energy material to confer water-repellent properties. These superhydrophobic surfaces were investigated to determine the parameters essential for reducing adhesion strength and delaying freezing time. A well-textured surface with nanopillars of very small top diameter, regardless of height, could reduce adhesion force and delay freezing time in a subsequent de-icing process. Small top diameters of nanopillars also ensured the metastable Cassie–Baxter state based on energy barrier calculations. The results demonstrated the important role of areal fraction in anti-icing efficiency, and the negligible contribution of texture height. This insight into icing phenomena should lead to design of improved ice-phobic surfaces in the future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Well-textured nanopillars with various parameters were fabricated for the anti-icing behavior. </LI> <LI> Nanopillars of very low top diameter irrelevant to height lead to reducing adhesion force and delaying freezing time. </LI> <LI> Low top diameter of nanopillars also ensures the metastable Cassie-Baxter state based on energy barrier calculation. </LI> <LI> Results demonstrated the important role of areal fraction and negligible contribution of height in anti-icing efficiency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Impacts of Organizational Factors on Work Motivation and Job Performance: Evidence from SMEs in Vietnam

Thanh Huong NGUYEN,Nguyen Danh NGUYEN,Binh Van TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.10

This study estimates the influence of organizational-level factors on work motivation and job performance of middle managers of small and medium enterprises (SMEs) in Vietnam. A 5-point-Likert-scale structural questionnaire consisting of 36 observation variables was used to survey middle managers of Vietnamese SMEs. 425 out of 500 responses collected were valid for multivariate data analysis. The results of confirmatory factor analysis and structural equation modeling reveal three main findings. First, philosophy and policy, compensation and benefits, goal system, and leadership have positively significant impacts on the work motivation of middle managers under investigation. Second, there is a significantly positive influence of work motivation on job performance. However, there is no indication that growth opportunities, work environment, evaluation system have significant impacts on the work motivation of respondents. Based on the findings, the study suggests four recommendations for Vietnamese SMEs to improve motivation and job performance of middle managers, which are (1) ensuring the clarity and soundness of the organizational policies and philosophies, especially human resources policy that boosts employees’ work motivation; (2) building a comprehensive compensation and benefit system to attract and retain talented employees; (3) developing a clear and adequate goal system; (4) enhancing top-level managers’ leadership abilities.

An Effective Moving Object Detection Method for Omnidirectional Camera

Thanh Binh Nguyen,Sun Tae Chung,HoSeok Kang,Seongwon Cho,Taein Seol 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.6

SMOOTHING APPROXIMATION TO l₁ EXACT PENALTY FUNCTION FOR CONSTRAINED OPTIMIZATION PROBLEMS

BINH, NGUYEN THANH The Korean Society for Computational and Applied M 2015 Journal of applied mathematics & informatics Vol.33 No.3

In this paper, a new smoothing approximation to the l₁ exact penalty function for constrained optimization problems (COP) is presented. It is shown that an optimal solution to the smoothing penalty optimization problem is an approximate optimal solution to the original optimization problem. Based on the smoothing penalty function, an algorithm is presented to solve COP, with its convergence under some conditions proved. Numerical examples illustrate that this algorithm is efficient in solving COP.