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This study presents a low-cost thyristor-controlled LC compensator scheme for the improvement of overall power quality in the distribution system. The parameters of the compensator have been designed and optimal triggering angles for thyristor switching have been obtained for reducing the unbalanced condition and harmonic injection at a high power factor. Compared to the traditional static VAr compensator schemes, the proposed technique can significantly reduce the harmonic injection into the system. The particle swarm optimization technique has been applied to compute the optimal triggering angles, and different aspects of the power quality factor have been assessed through rigorous simulations. Power quality assessment has been further validated through an experimental setup in the laboratory. Finally, a comparison of the proposed scheme with other similar schemes has been carried out to highlight its efficacy. [ABSTRACT FROM AUTHOR]

Usually, in mechanics, we obtain the trajectory of a particle in a given force field by solving Newton's second law with chosen initial conditions. In contrast, through our work here, we first demonstrate how one may analyze the behaviour of a suitably defined family of trajectories of a given mechanical system. Such an approach leads us to develop a mechanics analogue following the well-known Raychaudhuri equation largely studied in Riemannian geometry and general relativity. The idea of geodesic focusing, which is more familiar to a relativist, appears to be analogous to the meeting of trajectories of a mechanical system within a finite time. Applying our general results to the case of simple pendula, we obtain relevant quantitative consequences. Thereafter, we set up and perform a straightforward experiment based on a system with two pendula. The experimental results of this system are found to tally well with our proposed theoretical model. In summary, the simple theory and the related experiment provide us with a way to understand the essence of a fairly involved concept in advanced physics from an elementary standpoint. [ABSTRACT FROM AUTHOR]

The simple textbook problem of a particle on a vertical, rotating hoop is analysed both in theory and through experiments. We begin by detailing out a somewhat generalised theory, where the effect of dry friction as well as the possibility of a shift in the vertical axis of rotation are incorporated. The bifurcation curves (plots of the angular position of stability versus the angular frequency of rotation) are obtained for all cases (i.e. with and without friction and a shift of the axis). Thereafter we present the experimental set-up fabricated by us and elaborate on the various measurements performed. Finally, we demonstrate through our experiments how well the theoretical results on the bifurcation curves tally with the experimental findings. The match between theory and experiment is found to be reasonably satisfactory. We conclude by mentioning how various aspects of this simple problem as well as its generalisations and extensions, are linked with different advanced areas of physics. [ABSTRACT FROM AUTHOR]

In this article we revisit the much-studied behavior of self-assembled aggregates of gold colloidal particles. In the literature, the electrostatic interactions, van der Waals interactions, and the change in free energy due to ligand-ligand or ligand-solvent interactions are mainly considered to be the dominating factors in determining the characteristics of the gold aggregates. However, our light scattering and imaging experiments clearly indicate a distinct effect of light in the growth structure of the gold colloidal particles. We attribute this to the effect of a non-uniform distribution of the electric field in aggregated gold colloids under the influence of light. [ABSTRACT FROM AUTHOR]

Here, we report investigations on the instability in luminescence of bare (trioctylphosphine oxide [TOPO]-stabilized) and CdS-capped CdSe particles under infrared radiation. During thermal annealing under radiation, the formation of oxide layers on the surfaces of the particles create defect states. Consequently, there is a reduction in particle size. These two effects control the light output from the samples. We make a quantitative comparison of the stability of bare CdSe and core-shell-type CdSe-CdS particles during annealing under infrared radiation. Using diffusion theory, we show that the volume of the oxide layer, adhered to the crystallites, plays a dominant role in controlling the luminosity of the particles. [ABSTRACT FROM AUTHOR]