Ibrahim Abou Hamad

Floridian high-voltage power-grid network partitioning and cluster optimization using simulated annealing

Abstract Many partitioning methods may be used to partition a network into smaller clusters while minimizing the number of cuts needed. However, other considerations must also be taken into account when a network represents a real system such as a power grid. In this paper we use a simulated annealing Monte Carlo (MC) method to optimize initial clusters on the Florida highvoltage power-grid network that were formed by associating each load with its “closest” generator. The clusters are optimized to maximize internal connectivity within the individual clusters and minimize the power deficiency or surplus that clusters may otherwise have.

Spectral matrix methods for partitioning power grids: Applications to the Italian and Floridian high-voltage networks

Abstract Intentional islanding is used to limit cascading power failures by isolating highly connected “islands” with local generating capacity. To efficiently isolate an island, one should break as few power lines as possible. This is a graph partitioning problem, and here we give preliminary results on islanding of the Italian and Floridian high-voltage grids by spectral matrix methods.

Modeling power grids

We present a method to construct random model power grids that closely match statistical properties of a real power grid. The model grids are more difficult to partition than a real grid.

Effects of lateral diffusion on the dynamics of desorption

The adsorbate dynamics during simultaneous action of desorption and lateral adsorbate diffusion is studied in a simple lattice-gas model by kinetic Monte Carlo simulations. It is found that the action of the coverage-conserving diffusion process during the course of the desorption has two distinct, competing effects: a general acceleration of the desorption process, and a coarsening of the adsorbate configuration through Ostwald ripening. The balance between these two effects is governed by the structure of the adsorbate layer at the beginning of the desorption process.

EC-FORC: A New Cyclic-Voltammetry Based Method for Examining Phase Transitions and Predicting Equilibrium

We propose a new, cyclic-voltammetry based experimental technique that can not only differentiate between discontinuous and continuous phase transitions in an adsorbate layer, but also quite accurately recover equilibrium behavior from dynamic analysis of systems with a continuous phase transition. The Electrochemical first-order reversal curve (EC-FORC) diagram for a discontinuous phase transition (nucleation and growth), such as occurs in underpotential deposition, is characterized by a negative region, while such a region does not exist for a continuous phase transition, such as occurs in the electrosorption of Br on Ag(100). Moreover, for systems with a continuous phase transition, the minima of the individual EC-FORCs trace the equilibrium curve, even at very high scan rates. Since obtaining experimental data for the EC-FORC method would require only a simple reprogramming of the potentiostat used in conventional cyclic-voltammetry experiments, we belie ve that this method has significant potential for easy, rapid, in-situ analysis of systems undergoing electrochemical deposition.

A New Charging Method for Li-Ion Batteries: Dependence of the Charging Time on the Direction of an Additional Oscillating Field

We have recently proposed a new method for charging Li-ion batteries based on large-scale molecular dynamics studies (I. Abou Hamad et al, Phys. Chem. Chem. Phys., 12, 2740 (2010)). Applying an additional oscillating electric field in the direction perpendicular to the graphite sheets of the anode showed an exponential decrease in charging time with increasing amplitude of the applied oscillating field. Here we present new results exploring the effect on the charging time of changing the orientation of the oscillating field. Results for oscillating fields in three orthogonal directions are compared.