A COMPARISON OF DIFFUSION-LIMITED CURRENT AT MICROELECTRODES OF VARIOUS GEOMETRIES

2008 ◽  
Vol 07 (02) ◽  
pp. 205-219 ◽  
Author(s):  
R. SENTHAMARAI ◽  
L. RAJENDRAN
Keyword(s):  
Critical Evaluation ◽  
Circular Ring ◽  
Circular Disc ◽  
Graphical Form ◽  
Diffusion Limited ◽  
Limited Current ◽  
Elliptical Ring ◽  
Long Time ◽  
Nonsteady State ◽  
Time Variables

In this paper, we present a critical evaluation of the influence of geometry on the behavior of the transient current at all ultramicroelectrodes. The nonsteady-state chronoamperometric diffusion limited current of various microelectrodes (circular disc, circular ring, elliptical disc, elliptical ring, band, hemicylinder, hemisphere, hemioblate and hemiprolate electrodes) are compared. Here, the area of the entire electrode is fixed and time variables are also normalized with respect to area. The chronoamperometric current for short and long time for all microelectrodes are given in tabular as well as graphical form also.

scholarly journals PHASE PORTRAIT OF SECOND-ORDER DYNAMIC SYSTEMS

2018 ◽  
Vol 6 (3) ◽  
pp. 252-262 ◽  
Author(s):  
Kaloyan Yankov
Keyword(s):  
Phase Portrait ◽  
Plasma Renin ◽  
Higher Order ◽  
Second Order ◽  
Graphical Form ◽  
Time Behavior ◽  
Long Time ◽  
Phase Plane Method ◽  
The Stability ◽  
Higher Order Differential Equations

The phase portrait of the second and higher order differential equations presents in graphical form the behavior of the solution set without solving the equation. In this way, the stability of a dynamic system and its long-time behavior can be studied. The article explores the capabilities of Mathcad for analysis of systems by the phase plane method. A sequence of actions using Mathcad's operators to build phase portrait and phase trace analysis is proposed. The approach is illustrated by a model of plasma renin activity after treatment of experimental animals with nicardipine. The identified process is a differential equation of the second order. The algorithm is also applicable to systems of higher order.

TIP INSTABILITY DURING CONFINED DIFFUSION-LIMITED GROWTH

1988 ◽  
Vol 02 (08) ◽  
pp. 945-951 ◽  
Author(s):  
DAVID A. KESSLER ◽  
HERBERT LEVINE
Keyword(s):  
Evolution Equations ◽  
Dynamical Behavior ◽  
Stable Steady State ◽  
Time Behavior ◽  
Two Dimensional ◽  
Long Time Behavior ◽  
Limited Growth ◽  
Channel Geometry ◽  
Diffusion Limited ◽  
Long Time

We study diffusion-limited crystal growth in a two dimensional channel geometry. We demonstrate that although there exists a linearly stable steady-state finger solution of the pattern evolution equations, the true dynamical behavior can be controlled by a tip-widening instability. Possible scenarios for the long-time behavior of the system are presented.

scholarly journals Three Different Compact Elliptical Slot Ultra -Wide band Antennas for Wireless Communication Applications

2021 ◽  
pp. 52-59
Author(s):  
K. S Chakradhar ◽  
◽  
V. Malleswara Rao
Keyword(s):  
Frequency Band ◽  
Return Loss ◽  
Wide Band ◽  
Circular Ring ◽  
Ultra Wide Band ◽  
Impedance Bandwidth ◽  
Band Frequency ◽  
Uwb Antennas ◽  
Elliptical Ring ◽  
Pcb Design

From this current paper, 3 separate elliptical slotted ultra- wide band (UWB) antennas are being proposed. These antennas have been designed with a standard PCB design process to be capable of integrating with radiofrequency or microwave circuitry. Two designs were presented in which the initial design comprised a half circular ring radiator and the remaining one considers a half elliptical ring radiator. The third design of the radiator is in the shape of a crescent. The impedance bandwidth of all these presented antenna designs varies from 2.5GHz and reaches to 14GHz with a S11 less than -10GHz. Here, every proposed antenna design also has a consistent radiation pattern across its frequency band of interest. The performance of the antenna is impressive for lower band frequency in UWB system, which differs in a range of 3.1GHz to 5.1GHz. Across the whole frequency band the antenna shows a 10db return loss bandwidth. The antenna is fabricated on RT-duroid substrate and fed with 50 Ω coupled tappered transmission line.

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