scholarly journals Electrokinetics meets electrohydrodynamics

2015 ◽  
Vol 782 ◽  
pp. 1-4 ◽  
Author(s):  
Martin Z. Bazant
Keyword(s):  
Electric Fields ◽  
Double Layer ◽  
Liquid Electrolyte ◽  
Large Field ◽  
Fluid Interfaces ◽  
Major Step ◽  
Net Charge ◽  
Small Perturbations ◽  
Induced Flow ◽  
Future Work

Despite studying the same subject – electrically induced flow – the fields of electrokinetics (EK) and electrohydrodynamics (EHD) have developed separately, for different types of fluids and interfaces. In colloids or porous media, EK phenomena derive from the electro-osmotic slip of a liquid electrolyte across the neutral electric double layer on a solid surface. On the other hand, EHD phenomena involve poorly conducting neutral fluids and solids, whose interfaces acquire net charge in response to electric fields. Over the past decade, combined theories of EK and EHD have emerged for fluid/solid interfaces, and now Schnitzer & Yariv (J. Fluid Mech., vol. 773, 2015, pp. 1–33) have taken a major step towards unifying EK and EHD for fluid/fluid interfaces. Following previous work by Baygents and Saville, they derive the classical Taylor–Melcher model of droplet EHD as the large-field thin-double-layer limit of the electrokinetic equations, thus elucidating the ubiquitous ‘leaky dielectric’ approximation. Future work could consider the secondary electro-osmotic flow and electrophoretic motion of the drop (neglected here as small perturbations) and allow for more general EK models.

scholarly journals Parity–Time Symmetry in Bidirectionally Coupled Semiconductor Lasers

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 122 ◽  
Author(s):  
Andrew Wilkey ◽  
Joseph Suelzer ◽  
Yogesh Joglekar ◽  
Gautam Vemuri
Keyword(s):  
Semiconductor Lasers ◽  
Electric Fields ◽  
Single Mode ◽  
Equation Model ◽  
Rate Equations ◽  
Symmetric System ◽  
Time Symmetry ◽  
Complicating Factors ◽  
Future Work ◽  
Coupled Semiconductor

We report on the numerical analysis of intensity dynamics of a pair of mutually coupled, single-mode semiconductor lasers that are operated in a configuration that leads to features reminiscent of parity–time symmetry. Starting from the rate equations for the intracavity electric fields of the two lasers and the rate equations for carrier inversions, we show how these equations reduce to a simple 2 × 2 effective Hamiltonian that is identical to that of a typical parity–time (PT)-symmetric dimer. After establishing that a pair of coupled semiconductor lasers could be PT-symmetric, we solve the full set of rate equations and show that despite complicating factors like gain saturation and nonlinearities, the rate equation model predicts intensity dynamics that are akin to those in a PT-symmetric system. The article describes some of the advantages of using semiconductor lasers to realize a PT-symmetric system and concludes with some possible directions for future work on this system.

scholarly journals In situ investigation of dissociation and migration phenomena at the Pt/electrolyte interface of an electrochemical cell

2015 ◽  
Vol 6 (10) ◽  
pp. 5635-5642 ◽  
Author(s):  
Yeuk Ting Law ◽  
Spyridon Zafeiratos ◽  
Stylianos G. Neophytides ◽  
Alin Orfanidi ◽  
Dominique Costa ◽  
...  
Keyword(s):  
Double Layer ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Cell ◽  
Ambient Pressure ◽  
Liquid Electrolyte ◽  
X Ray ◽  
Electrolyte Interface ◽  
In Situ Investigation ◽  
And Migration

Using near ambient pressure X-ray photoelectron spectroscopy we probe in situ the double layer at the Pt/liquid electrolyte interface.

Simulation of diffuse-charge capacitance in electric double layer capacitors

2017 ◽  
Vol 31 (01) ◽  
pp. 1650431 ◽  
Author(s):  
Ning Sun ◽  
Dilip Gersappe
Keyword(s):  
Double Layer ◽  
Electric Double Layer ◽  
Lattice Boltzmann Model ◽  
Concentrated Solutions ◽  
Net Charge ◽  
Random Spheres ◽  
Boltzmann Model ◽  
Double Layer Capacitors ◽  
Charge Capacitance ◽  
Electric Double Layer Capacitors

We use a Lattice Boltzmann Model (LBM) in order to simulate diffuse-charge dynamics in Electric Double Layer Capacitors (EDLCs). Simulations are carried out for both the charge and the discharge processes on 2D systems of complex random electrode geometries (pure random, random spheres and random fibers). The steric effect of concentrated solutions is considered by using a Modified Poisson–Nernst–Planck (MPNP) equations and compared with regular Poisson–Nernst–Planck (PNP) systems. The effects of electrode microstructures (electrode density, electrode filler morphology, filler size, etc.) on the net charge distribution and charge/discharge time are studied in detail. The influence of applied potential during discharging process is also discussed. Our studies show how electrode morphology can be used to tailor the properties of supercapacitors.

scholarly journals Fluid flow induced by nonuniform ac electric fields in electrolytes on microelectrodes. II. A linear double-layer analysis

2000 ◽  
Vol 61 (4) ◽  
pp. 4019-4028 ◽  
Author(s):  
A. González ◽  
A. Ramos ◽  
N. G. Green ◽  
A. Castellanos ◽  
H. Morgan
Keyword(s):  
Fluid Flow ◽  
Electric Fields ◽  
Double Layer ◽  
Ac Electric Fields ◽  
Layer Analysis

Forces between dissimilar colloidal plates for various surface conditions. II. Equilibrium adsorption effects

1981 ◽  
Vol 59 (13) ◽  
pp. 1888-1897 ◽  
Author(s):  
G. M. Bell ◽  
G. C. Peterson
Keyword(s):  
Charge Density ◽  
Double Layer ◽  
Equilibrium Adsorption ◽  
Total Charge ◽  
Net Charge ◽  
Adsorption Models ◽  
Ionic Adsorption ◽  
Counter Ions ◽  
Weak Adsorption ◽  
Anions And Cations

A method previously developed by the authors is used to study the effects of adsorption of ions on the electric double layer interaction between dissimilar colloidal plates immersed in 1:1 electrolyte. For adsorption models which permit the total charge on a plate to change sign, the double layer force remains finite at all plate separations, including zero. For weak adsorption of the ions on the plates the force between two dissimilar plates tends to be repulsive at small separations, looking rather like a weakened constant surface charge density model. Conversely for strong ionic adsorption the force tends to be attractive at small separations, rather as in the constant surface potential model. In this paper we discuss three adsorption models: (1) fixed primary charge density on the plates with secondary adsorption of both counter-ions and co-ions; (2) fixed primary charge density on the plates with secondary adsorption of the counter-ions only, but including the effects of a Stern layer and self-atmosphere potentials; (3) zero primary charge on both plates with equilibrium adsorption of both anions and cations from solution, the net charge density on the plates arising from differential adsorption of the ion types.

scholarly journals The Eccoe Approach to Quality Reviewing Online Descriptions of Learning Opportunities

2020 ◽  
pp. 66-75
Author(s):  
Deborah Arnold ◽  
Alessandra Antonaci ◽  
Lisa Marie Blaschke ◽  
Gérard Casanova ◽  
Ada Giannatelli ◽  
...  
Keyword(s):  
Quality Criteria ◽  
Learning Opportunities ◽  
Online Information ◽  
Actual Process ◽  
The European Union ◽  
Major Step ◽  
Flexible Learning ◽  
Learning Opportunity ◽  
Stakeholder Consultation ◽  
Future Work

As learners seek more flexible learning opportunities, and employers become gradually more open to accepting alternative forms of credentials, there is a need to improve the visibility and quality of the online information available about such opportunities. This information includes not only the descriptions of formal and non-formal learning opportunities, from full degree programmes to optional courses and MOOCs, but also the credentials learning opportunities can lead to and by whom these credentials are recognised. The new Europass initiative of the European Union is a major step forward in this respect, offering the possibility to search for both learning and employment opportunities via a platform that will support a variety of different credentials. Building on the Europass Learning Model, the Erasmus+ ECCOE project makes a significant contribution to this future platform, by defining specific quality criteria for evaluating both learning opportunities and their credentials. This paper describes the methodology applied for the quality review of online descriptions with the ultimate aim of developing a catalogue showcasing learning opportunities that meet the criteria defined by the project. This methodology concerns two levels: (a) the actual process designed and implemented transnationally for the first iteration of over 100 learning opportunity descriptions, and (b) the two PDCA (Plan, Do, Check, Act) quality improvement cycles applied to refining the process itself. The paper also presents the results of this first iteration and formulates recommendations relevant for learning opportunity providers. Future work involving stakeholder consultation is also presented, as are the synergistic interactions between this research and the overall ECCOE project outcomes within the wider context of European work on Digital Credentials and open, online and flexible learning.

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