Browsing by Author "Huang, Yu-Sheng"

Now showing 1 - 10 of 10

A numerical study on radial Hele-Shaw flow: influence of fluid miscibility and injection scheme
(2015-02-01)
Huang, Yu-Sheng
;
Chen, Ching-Yao
;
機械工程學系
;
Department of Mechanical Engineering
Fingering instability triggered by injection of a less viscous fluid in a Hele-Shaw cell is numerically investigated. Simulations are based on a diffuse-interface method, and the formulation, capable of dealing with immiscible and miscible interfaces, is presented in details. Three miscibility conditions, including immiscible with surface tension, partially miscible with effective interfacial tension and fully miscible without interfacial stresses, are simulated to verify generality of an optimal linear injection scheme proposed by Dias et al. (Phys Rev Lett 109:144502, 2012) in the limit of infinite viscosity contrast. stabilizing effects of this linear injection scheme are universally confirmed for the interfaces with the presence of interfacial stresses, such as immiscible and partially miscible conditions. On the other hand, the linear injection scheme in a fully miscible interface leads to contradictory results. Even the fingering pattern appears qualitatively more stable without the secondary phenomenon of finger merging, relevant quantitative measurements, such as longer channeling zone and interfacial length, indicate enhancement of fingering prominence. The inconsistent behaviors suggest that the coupling effects with the interfacial stresses are crucial in the applications of the optimal linear injection scheme.
An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn(2+)
(2011-11-01)
Chao, Yu-Chiang
;
Huang, Yi-Sa
;
Wang, Hsin-Ping
;
Fu, Ssu-Ming
;
Huang, Chien-Hao
A hydrogel sensing film for a real-time and indicator-free detection of Zn(2+) is developed by embedding a fluorescent indicator 11,16-bis( phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn(2+). The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn(2+) concentrations of 10 (4) and 10 (3) M, the response time is 30 and 3 s, respectively. (C) 2011 Elsevier B.V. All rights reserved.
An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn2+
(2011-11-01)
Chao, Yu-Chiang
;
Huang, Yi-Sa
;
Wang, Hsin-Ping
;
Fu, Ssu-Ming
;
Huang, Chien-Hao
A hydrogel sensing film for a real-time and indicator-free detection of Zn2+ is developed by embedding a fluorescent indicator 11,16-bis( phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn2+. The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn2+ concentrations of 10 (4) and 10 (3) M, the response time is 30 and 3 s, respectively. (C) 2011 Elsevier B.V. All rights reserved.
Diffuse-interface approach to rotating Hele-Shaw flows
(2011-10-05)
Chen, Ching-Yao
;
Huang, Yu-Sheng
;
Miranda, Jose A.
;
機械工程學系
;
Department of Mechanical Engineering
When two fluids of different densities move in a rotating Hele-Shaw cell, the interface between them becomes centrifugally unstable and deforms. Depending on the viscosity contrast of the system, distinct types of complex patterns arise at the fluid-fluid boundary. Deformations can also induce the emergence of interfacial singularities and topological changes such as droplet pinch-off and self-intersection. We present numerical simulations based on a diffuse-interface model for this particular two-phase displacement that capture a variety of pattern-forming behaviors. This is implemented by employing a Boussinesq Hele-Shaw-Cahn-Hilliard approach, considering the whole range of possible values for the viscosity contrast, and by including inertial effects due to the Coriolis force. The role played by these two physical contributions on the development of interface singularities is illustrated and discussed.
Enhanced mixing via alternating injection in radial Hele-Shaw flows
(2015-10-07)
Chen, Ching-Yao
;
Huang, Yi-Cheng
;
Huang, Yu-Sheng
;
Miranda, Jose A.
;
機械工程學系
Mixing at low Reynolds numbers, especially in the framework of confined flows occurring in Hele-Shaw cells, porous media, and microfluidic devices, has attracted considerable attention lately. Under such circumstances, enhanced mixing is limited due to the lack of turbulence, and absence of sizable inertial effects. Recent studies, performed in rectangular Hele-Shaw cells, have demonstrated that the combined action of viscous fluid fingering and alternating injection can dramatically improve mixing efficiency. In this work, we revisit this important fluid mechanical problem, and analyze it in the context of radial Hele-Shaw flows. The development of radial fingering instabilities under alternating injection conditions is investigated by intensive numerical simulations. We focus on the impact of the relevant physical parameters of the problem (Peclet number Pe, viscosity contrast A, and injection time interval Delta t) on fluid mixing performance.
Fully Digital Driving Circuit for TFT LCD Using the Concept of Ramp-Stop
(2019-03-01)
Tai, Ya-Hsiang
;
Lin, Chi-Hao
;
Ho, Tsung-Hsuan
;
Huang, Yu-Sheng
;
Huang, Sheng-Miao
A fully digital driving circuit for thin-film transistor liquid crystal display can offer benefits, including less power consumption and a shortened design schedule. Using the pulsewidth signal to control the moment to stop the ramp voltage, the pixel voltage can be set accurately. In this paper, the possible issues of power consumption, device nonuniformity, and parasitic capacitance are well-studied to prove the feasibility and advantages of the digital driving method. It is prospectively expected to substitute for the conventional analog driving method in the future.
Radial Hele-Shaw flow with suction: Fully nonlinear pattern formation
(2014-05-09)
Chen, Ching-Yao
;
Huang, Yu-Sheng
;
Miranda, Jose A.
;
機械工程學系
;
Department of Mechanical Engineering
We study the development of intricate, fully nonlinear immiscible interfacial patterns in the suction-driven radial Hele-Shaw problem. The complex-shaped, contracting fluid-fluid interface arises when an initially circular blob of more viscous fluid, surrounded by less viscous one, is drawn into an eccentric point sink. We present sophisticated numerical simulations, based on a diffuse interface model, that capture the most prominent interfacial features revealed by existing experimental studies of the problem. The response of the system to changes in the capillary number is investigated, accurately revealing the occurrence of finger competition phenomena, and correctly describing the velocity behavior of both inward-and outward-pointing fingers. For the large-capillary-number regime, a set of complex interfacial features (finger merging, shielding, and pinch-off) whose experimental realization is still not available, are predicted.
Shape-Tunable SrTiO3 Crystals Revealing Facet-Dependent Optical and Photocatalytic Properties
(2019-06-06)
Hsieh, Pei-Lun
;
Naresh, Gollapally
;
Huang, Yu-Sheng
;
Tsao, Chun-Wen
;
Hsu, Yung-Jung
SrTiO3 cubes with tunable sizes of 160-290 nm have been synthesized by mixing TiCl4, SrCl2, and LiOH in pure ethanol or a water/ethanol mixed solution at just 70 degrees C for 3 h. Replacing water/ethanol with water/hexanol and water/ethylene glycol, and fine tuning the amounts of other reagents, resulted in the formation of edge-truncated cubes and {100}-truncated rhombic dodecahedra, respectively. X-ray diffraction and transmission electron microscopy characterization, supported by Rietveld refinement analysis, have revealed shape-dependent tuning in lattice parameters. The cubes display slight size-related optical band shifts, and they show clearly more blue-shifted light absorption than the other particles exposing significant {110} faces. The {100}-truncated rhombic dodecahedra are far more efficient than cubes at photodegradation of methylene blue and photocatalyzed hydrogen evolution from water in the presence of methanol. The photocatalytic activity variation should arise from different degrees of surface band bending for the {100} and {110} faces of SrTiO3, suggesting surface facet control as a strategy for enhancing photocatalyzed hydrogen production.
Single-layered multi-color electrowetting display by using ink-jet-printing technology and fluid-motion prediction with simulation
(2011-07-01)
Ku, Yun-Sheng
;
Kuo, Shu-Wei
;
Huang, Yu-Sheng
;
Chen, Ching-Yao
;
Lo, Kuo-Long
This paper describes a single-layered multi-color electrowetting display (EWD) by using ink-jet-printing (IJP) technology and comparing different pattern electrodes with the use of the numerical investigations of ANSYS FLUENT (R). This work consists of two parts: the first describes the design of implementing a single-layered multi-color EWD and the second demonstrates the application of ANSYS FLUENT (R) simulation in different pattern electrodes settings on the proposed EWD. The single-layered multi-color EW device was evaluated by using various colored oils without adopting a color filter. The single-layered multi-color EWD at a driving voltage of 25 V can achieve a maximum aperture ratio and reflectivity of 80% and 38.5%, respectively. The colored saturation of R, G, B oils can increase to 50% (NTSC: 13.3-27.8%). In addition, a radiate electrode at the required viewable area condition of 85% and force 5 * F(k), which results in ink stable contraction and a shorter response time of 50% (radiate vs. square), was proposed. The experimental results and simulation demonstrate that ink-jet-printing (IJP) technology along with the use of radiate electrodes can result in a single-layered multi-color EWD with a shorter response time.
Transparent AAA Security Design for Low-Latency MEC-Integrated Cellular Networks
(2020-03-01)
Li, Chi-Yu
;
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
Chien, Hsu-Tung
;
Huang, Yu-Sheng
Multi-access edge computing (MEC) is a key enabler for low-latency services in the cellular network. It enables service requests to be served at the edge without reaching the Internet. However, this service model allows data traffic to bypass conventional security functions deployed at the core network, and may pose security threats. To examine its security impact, we analyze current security functions that span authentication, authorization, accounting (AAA), and access control, and then identify two major issues. First, conventional user authentication methods prevent MEC applications from achieving low-latency service offering. Second, current cellular authorization, accounting, and access control mechanisms hardly secure MEC traffic. We thus propose a transparent security design called MECsec to secure the MEC with low latency in the cellular network. It contains three main components: cellular-based OpenID Connect (OIDC) authentication, bitmap-based authorization/accounting, and two-tier hash-based access control. Especially, its transparent design does not need any changes on current cellular operations, and is standard-compliant. We implement and evaluate the MECsec prototype on an MEC-integrated LTE network architecture developed based on the OpenAirInterface (OAI) cellular platform. Our results show that the cellular-based OIDC can reduce delays of current authentication methods by up to 88.3%, and the other components can successfully defend against possible threats with negligible overhead.