Carbon nanotubes can be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal –semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque and the current are shown to...

This paper proposes to utilize intentional time delays as part of controllers improve the damping electromechanical oscillations power systems. Through stability theory, control parameter settings for which these in Power System Stabilizers (PSSs) small signal a system are systematically identified, including key regions plane remain connected effective operation. The shows that PSSs with two c...

Power systems are usually large non-linear systems, which are often subjected to low frequency electromechanical oscillations. Power System Stabilizers (PSSs) are often used as effective and economic means for damping the generators’ electromechanical oscillations and enhance the overall stability of power systems. Power system stabilizers have been applied for several decades in utilities and ...

The steady-state stability limit and the system positive damping can be improved by conventional Power System Stabilizer (PSS). However, in order to have abilities such as the online tuning and optimal real-time damping in the entire operating range, robust design of PSS in required. A novel robust PSS design using Artificial Neural Network (ANN) and Imperialist Competitive Algorithm (ICA) for ...

Damping of inter-area electromechanical oscillations is one of the major challenges to the electric power system operators. This paper presents Gravitational Search Algorithm (GSA) for tuning Static Synchronous Series Compensator (SSSC) based damping controller to improve power system oscillation stability. In the proposed algorithm, the searcher agents are a collection of masses which interact...

We combine electromechanical measurements with ab initio density-functional calculations to settle the controversy about the origin of torsion-induced conductance oscillations in multiwall carbon nanotubes. Contrary to intuition, the observed oscillation period in multiwall tubes exhibits the same inverse-squared diameter dependence as in single-wall tubes with the same diameter. This finding s...

Due to the deregulation of the electrical market, difficulty in acquiring rights-of-way to build new transmission lines, and steady increase in power demand, maintaining power system stability becomes a difficult and very challenging problem. In large, interconnected power systems, power system damping is often reduced, leading to lightly damped electromechanical modes of oscillations. Implemen...

Presently, there are two main aspects which allow to reduce the operating as well as the cold reserve power to be kept ready by individual network partners in order to maintain the power system reliability. First, the transmission lines, generators and loads are interconnected into large-scale and complex integrated systems. An important benefit brought about by the interconnected operation is ...