Using Superhydrophobic SU-8 Film as the Dielectric for Electrowetting-on-Dielectric

2018 ◽  
Vol 281 ◽  
pp. 604-609
Author(s):  
Yu Hao Piao ◽  
Wei Qiang Wang
Keyword(s):  
Contact Angle ◽  
Dielectric Layer ◽  
Superhydrophobic Surface ◽  
High Performance ◽  
Apparent Contact Angle ◽  
Experimental Results ◽  
Electrowetting On Dielectric ◽  
Dc Voltage ◽  
Theoretical Predictions ◽  
Good Agreement

In this paper, we study the electrowetting effect of superhydrophobic SU-8 film as the dielectric for Electrowetting-on-Dielectric (EWOD). The change of apparent contact angle (APCA) on superhydrophobic surface in electrowetting systems was measured and analyzed using a modified Lippmann-Yong equation. The variation of APCA between droplet and device surface under various DC voltage and AC voltage of different frequencies was fully experimented. The experimental results were in good agreement with the theoretical predictions. This study shows the potential of using superhydrophobic SU-8 film as the dielectric layer in high-performance EWOD devices.

Explicit formulation for the axial collapse of a pipe during drilling

2010 ◽  
Vol 224 (8) ◽  
pp. 1547-1549
Author(s):  
A Almasi
Keyword(s):  
Closed Form ◽  
Plastic Hinge ◽  
Variable Length ◽  
Experimental Results ◽  
Displacement Curve ◽  
Explicit Formulation ◽  
Theoretical Predictions ◽  
Hinge Zone ◽  
Good Agreement

New closed-form expressions are introduced for ax-symmetric progressive axial collapse of pipes that use a plastic folding mechanism based on variable length of an active plastic hinge zone. A procedure for determination of a load—displacement curve of axial pipe collapse is presented. Theoretical predictions give a good agreement with the experimental results owing to the influence of presented new refinements.

Measurement of sheath characteristics in the presence of convection and ionization

1996 ◽  
Vol 74 (9-10) ◽  
pp. 671-675 ◽  
Author(s):  
R. M. Clements ◽  
J. R. Dawe ◽  
S. A. H. Rizvi ◽  
P. R. Smy
Keyword(s):  
Boundary Layer ◽  
Plasma Electron ◽  
Experimental Results ◽  
Ion Density ◽  
Current Voltage ◽  
Planar Grid ◽  
Theoretical Predictions ◽  
Flame Plasma ◽  
Theoretical Paper ◽  
Good Agreement

A flame plasma whose electron and (or) ion density can be varied over several orders of magnitude is constrained to flow perpendicular to a planar grid Langmuir probe. The probe is biased negative to the plasma, and the current–voltage characteristics and the thickness of the ion sheath formed at the probe are measured. The level of the electron and (or) ion density is set within a range at which the probe current due to thermal ionization throughout the sheath is comparable with the current of ions convected into the sheath. The experimental results are compared with the predictions of a recent theoretical paper that calculates the effect of recombination upon the characteristics of planar, cylindrical, and spherical probes with boundary layer sheaths. The theoretical predictions and experimental results for an idealized planar configuration show good agreement over wide ranges of variation of probe bias and plasma electron and (or) ion density. This verification of the theoretical planar electrode – perpendicular-flow model, which is the basis for all three boundary layer relations, is seen as providing strong backing for these relations, which have application to ionization measurements in various forms of recombinant plasma.

Paper 31: Capsule-Pipeline Flow—A Theoretical Study

1969 ◽  
Vol 184 (7) ◽  
pp. 89-100
Author(s):  
V. K. Garg ◽  
G. F. Round
Keyword(s):  
Theoretical Study ◽  
Theoretical Solution ◽  
Experimental Results ◽  
Free Flow ◽  
Average Flow ◽  
Pipe System ◽  
Liquid Carrier ◽  
Pipeline Flow ◽  
Theoretical Predictions ◽  
Good Agreement

Theoretical predictions of the behaviour of various parameters governing the free flow of a single, very long, denser-than-liquid carrier, cylindrical capsule in a horizontal pipeline are reported in this paper. The study was carried out for average flow velocities of approximately 1–10 ft/s in pipes of diameters 4, 6, 12, and 24 in with diameter ratios varying from 0·9 to 0·99. While two liquid carriers—water and an oil ( μ = 10 cP and sp. gr. = 0·85)—were used, the eccentricity of the capsule-pipe system was fixed at 0·999. The theoretical solution was found to be in good agreement with the experimental results.

Coalescence-induced jumping of nanodroplets on mixed-wettability superhydrophobic surfaces

2020 ◽  
Author(s):  
Fang-Fang Xie ◽  
Dan-Qi Wang ◽  
Yi-Bo Wang ◽  
Yan-Ru Yang ◽  
Xiao-Dong Wang
Keyword(s):  
Contact Angle ◽  
Superhydrophobic Surface ◽  
Apparent Contact Angle ◽  
Superhydrophobic Surfaces ◽  
Dominant Factor ◽  
Heterogeneous Surfaces ◽  
Transfer Enhancement ◽  
Stripe Width ◽  
Mixed Wettability ◽  
Dynamics Simulations

Coalescence-induced droplet jumping on superhydrophobic surfaces has been observed at microscale and even nanoscale. The enhancement in jumping velocity of coalescing droplets is crucial for condensation heat transfer enhancement, anti-icing, self-cleaning, and so forth. However, the research on how to acquire a higher jumping velocity is really very limited. In this paper, we use molecular dynamics simulations to study the coalescence-induced jumping of two equally-sized nanodroplets on chemically heterogeneous surfaces composed of alternating stripes with different hydrophobicity. We show that the jumping velocity is closely related to the stripe width and wettability contrast, and it can even exceed that on an ideal superhydrophobic surface with 180° contact angle when the striped surfaces are properly designed. We also demonstrate that there is always an optimal stripe width yielding the maximum jumping velocity, whereas its value is independent of the wettability contrast. We reveal that the dominant factor to determine the jumping velocity is the apparent contact angle of equilibrated droplets over heterogeneous surfaces for small stripe widths, it changes to the time of liquid bridges impacting surfaces for moderate stripe widths and to the contact area between equilibrated droplets and relatively hydrophobic stripes for large stripe widths. We believe the present simulations can provide useful guidance to design self-jumping superhydrophobic surfaces.

The bursting of a charged cylindrical film

1972 ◽  
Vol 328 (1575) ◽  
pp. 529-539 ◽  
Keyword(s):  
Experimental Data ◽  
Finite Length ◽  
Experimental Results ◽  
Exact Calculation ◽  
Conducting Film ◽  
Half Wavelength ◽  
Theoretical Predictions ◽  
Long Cylinder ◽  
Good Agreement

This paper is a sequel to Sir Geoffrey Taylor’s study of the bursting of an electrified cylindrical conducting film. Taylor described experiments in which the voltages, at which the film becomes statically unstable, were observed for various lengths of film. These results were compared with the theoretical predictions for disturbances on an infinitely long cylinder having a wavelength equal to the length of film used. It is shown here that a transition in the mode of bursting from an axisymmetric whole wavelength mode to a lateral half wavelength mode is to be expected and that the experimental data conform with this transition. An exact calculation of the modes for a film of finite length is also given here and the resulting theoretical predictions of instability and bursting voltages are in very good agreement with the experimental results.

Effect of Textures on the Nanomechanical Properties of Nanocrystalline Fe-50%Ni Foil

2006 ◽  
Vol 15-17 ◽  
pp. 923-928
Author(s):  
Jong Kweon Kim ◽  
Shi Hoon Choi ◽  
Yong Bum Park
Keyword(s):  
Elastic Modulus ◽  
Sample Thickness ◽  
Experimental Results ◽  
Nanoindentation Test ◽  
Specimen Thickness ◽  
Strong Decrease ◽  
Nanomechanical Properties ◽  
Texture Change ◽  
Theoretical Predictions ◽  
Good Agreement

The textures and nanomechanical properties of nanocrystalline Fe-50wt%Ni foil fabricated by using an electroforming method were investigated. The as-deposited texture was characterized by major <100>//ND and minor <111>//ND fibre components. Annealing of the as-deposited specimen resulted in the texture change that the <111>//ND fibre texture developed strongly with decreasing <100>//ND intensity. The elastic modulus and hardness were investigated by nanoindentation test, and these experimental results were compared with the theoretical predictions based on an elastic self-consistent (ESC) polycrystal model. Annealing led to an increase in the elastic modulus and a strong decrease in the hardness. At the low ratio of indentation depth to the specimen thickness, the theoretical predictions of the elastic modulus in the sample thickness direction showed a good agreement with experimental results.

Theoretical Prediction and Experimental Study of Mechanical Properties for Random and Magnetically Aligned Single-Walled Carbon Nanotube/Epoxy Composites

2003 ◽  
Vol 791 ◽  
Author(s):  
Ben Wang ◽  
Ravi Shankar ◽  
Zhiyong Liang ◽  
Zhi Wang ◽  
Chuck Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
High Performance ◽  
Experimental Results ◽  
Reinforced Composites ◽  
Polymeric Nanocomposites ◽  
Single Walled Carbon ◽  
Theoretical Predictions ◽  
Walled Carbon Nanotubes ◽  
Magnetically Aligned

ABSTRACTSingle-walled carbon nanotubes (SWNTs) have exceptional mechanical and functional properties. Many researchers consider SWNTs as the most promising reinforcement for realizing the optimal structural and multifunctional potential of the next generation of high performance nanocomposites. However, due to poor dispersion, weak interfacial bonding and deficient tube orientation, current nanotube-based nanocomposites fail to realize their anticipated properties. A new approach was developed by the authors to use preformed nanotube tube networks (called buckypapers) and a resin infiltration method for producing bulk polymeric nanocomposites with controlled nanostructure and high tube loading. Desired tube alignment in nanocomposites can be achieved by using magnetically aligned carbon nanotube buckypapers, in which SWNTs will tend to align along the direction of applied magnetic field. The mechanical properties of the resultant nanocomposites have been tested. The storage modulus of the magnetically aligned nanocomposites is as high as 47 GPa, which is one of the highest reported values of nanotube-reinforced composites.In this research, we investigated the influences of tube dispersion, loading and orientation on the mechanical properties of SWNT-reinforced composites. Random and aligned discontinuous reinforcement models of composites were applied to predict the tensile moduli of both individually dispersed SWNT-based and SWNT rope-based nanocomposites. The nanostructural parameters used in the calculation models were determined based on our experimental observations. Comparisons between theoretical estimates and experimental results have shown that the formation of SWNT ropes in the composites has a significant influence on the mechanical properties. The experimental results of the both random and aligned SWNT rope composites are in good agreement with the theoretical predictions.

THE E-PLANE RADIATION PATTERN OF SHORT ELECTROMAGNETIC HORNS OF LARGE APERTURE

1947 ◽  
Vol 25a (6) ◽  
pp. 315-321 ◽  
Author(s):  
G. A. Woonton ◽  
J. G. Tillotson
Keyword(s):  
Electromagnetic Field ◽  
Diffraction Pattern ◽  
Radiation Pattern ◽  
Wave Length ◽  
Angular Position ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electric Vector ◽  
Theoretical Predictions ◽  
Good Agreement

The relation between the power received by a short, rectangular, electromagnetic horn, and its angular position in a plane electromagnetic field can be calculated, for rotation in the plane of the electric vector, from ordinary optical theory by assuming that the aperture produces at the throat a Fresnel diffraction pattern appropriate to the angular position of the aperture. Experimental results for four horns of slant lengths 25, 50, 100, and 176 cm., but all of the same aperture, 10λ to a side at a wave length of 3.2 cm., are in good agreement with the theoretical predictions at angles up to [Formula: see text] radian from the axis, for slant lengths down to 50 cm. but not down to 25 cm.

The Energy Transition on Superhydrophobic Surface by Electrowetting Control

2009 ◽  
Vol 79-82 ◽  
pp. 91-94
Author(s):  
Jun Wu ◽  
Jun Xia ◽  
B.P. Wang
Keyword(s):  
Contact Angle ◽  
Silicon Nanowires ◽  
Superhydrophobic Surface ◽  
Saline Solution ◽  
Energy Transition ◽  
Apparent Contact Angle ◽  
Superhydrophobic Surfaces ◽  
External Voltage ◽  
Field Temperature ◽  
Substantial Interest

Transition between Wenzel and Cassie states on superhydrophobic surface has attracted substantial interest from various research communities. The transition between the two states is realized by the methods of changing surface structure in micron scale, or changing the surface tension between a droplet and a solid surface through external electric field, temperature, light, etc. In this paper we design a rough surface on aluminum substrate with the etching processes, on which a large superhydrophobic surface is achieved easily and economically. On this surface, a drop of saline solution water forms a nearly perfect spherical pearl with the apparent contact angle over than 160°. By applying external voltage between the substrate and the solution, we observe a different electrowetting phenomenon from the case on other superhydrophobic surfaces, i.e. on silicon nanowires coated with hydrophobic fluoropolymer C4F8. This difference is discussed and explained by asymmetry of the superhydrophobic surface which increases the hysteresis. A saturated apparent contact angle is also observed as the applied voltage increased to a specific value.

An R-Curve Approach for Fracture of Ultra High Performance Cementitious Composites

2007 ◽  
Vol 348-349 ◽  
pp. 825-828
Author(s):  
Xiang Guo Wu ◽  
Sang Mook Han ◽  
Sung Wook Kim ◽  
Su Tae Kang
Keyword(s):  
Stress Intensity Factor ◽  
High Performance ◽  
Steel Fiber ◽  
Unit Area ◽  
Cementitious Composites ◽  
Test Results ◽  
Linear Distribution ◽  
Three Point Bending ◽  
Theoretical Predictions ◽  
Good Agreement

An R-curve formula for ultra high performance cementitious composites is derived in this paper. The fracture mechanics based on R-curve is used to predict the load-deflection relation of ultra high performance cementitious composites. The reductions of stress intensity factor and CTOD by steel fiber reinforcement are assumed as conforming linear distribution along crack propagation. The effective numbers of steel fiber on unit area based uniform distribution is used here. Results of the theoretical predictions show a good agreement with test results of three point bending beam of UHPCC. The modified R-curve formula for UHPCC can be a reference for future study of fracture performances of UHPCC.

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