Abstract:
Multilevel inverter (MLI)
is one of the most efficient power converters which are especially suited for
high power applications with reduced harmonics. MLI not only achieves high
output power and is also used in renewable energy sources such as photovoltaic,
wind and fuel cells. Among various topologies of MLI, this paper mainly focuses
on cascaded MLI with three unequal DC sources called asymmetric cascaded MLI
which reduces the number of power switches. Various modulation techniques are
also reviewed in literature？[1]. In this paper we focus on
sinusoidal (or) multicarrier pulse width modulation (SPWM) which improves the
output voltage at lower modulation index for obtaining lower Total Harmonic
Distortion (THD) level. The gating signal for the 13-level hybrid inverter
using SPWM technique is generated using Field Programmable Gate Array (FPGA)
processor. The proposed modulation technique results in reduced percentage of
THD, but lower order harmonics are not eliminated. So a new technique called
Selective Harmonic Elimination (SHE) is also implemented in order to reduce the
lower order harmonics. The optimum switching angles are determined for
obtaining minimum THD. The performance evaluation of the proposed PWM inverter
is verified using an experimental model of 13-level cascaded hybrid MLI and
compared with MATLAB/SIMULINK model.

Abstract:
This paper presents the methodology, properties and
processing of the time-frequency techniques for non-stationary signals, which are frequently used in biomedical, communication and image processing
fields. Two classes of time-frequency analysis techniques are chosen for this
study. One is short-time Fourier Transform (STFT) technique from linear
time-frequency analysis and the other is the Wigner-Ville Distribution (WVD)
from Quadratic time-frequency analysis technique. Algorithms for both these
techniques are developed and implemented on non-stationary signals for spectrum
analysis. The results of this study revealed that the WVD and its classes are
most suitable for time-frequency analysis.

Abstract:
A system of two coupled cavities is studied in the context of bipartite, continuous variable entanglement. One of the cavities is pumped by an external classical source that is coupled quadratically, to the cavity field. Dynamics of entanglement, quantified by covariance measure [Dodonov {\it et al}, Phys. Lett A {\bf 296}, (2002) 73], in the presence of cavity-cavity coupling and external pumping is investigated. The importance of tailoring the coupling between the cavities is brought out by studying the effects of pump fluctuations on the entanglement.

Abstract:
Entanglement in a class of bipartite generalized coherent states is discussed. It is shown that a positive parameter can be associated with the bipartite generalized coherent states so that the states with equal value for the parameter are of equal entanglement. It is shown that the maximum possible entanglement of 1 bit is attained if the positive parameter equals $\sqrt{2}$. The result that the entanglement is one bit when the relative phase between the composing states is $\pi$ in bipartite coherent states is shown to be true for the class of bipartite generalized coherent states considered.

Abstract:
Entanglement of bosonic modes of material oscillators is studied in the context of two bilinearly coupled, nonlinear oscillators. These oscillators are realizable in the vibrational-cum-bending motions of C-H bonds in dihalomethanes. The bilinear coupling gives rise to invariant subspaces in the Hilbert space of the two oscillators. The number of separable states in any invariant subspace is one more than the dimension of the space. The dynamics of the oscillators when the initial state belongs to an invariant subspace is studied. In particular, the dynamics of the system when the initial state is such that the total energy is concentrated in one of the modes is studied and compared with the evolution of the system when the initial state is such wherein the modes share the total energy. The dynamics of quantities such as entropy, mean of number of quanta in the two modes and variances in the quadratures of the two modes are studied. Possibility of generating maximally entangled states is indicated.

Abstract:
Interaction of a two-level atom with a single mode of electromagnetic field including Kerr nonlinearity for the field and intensity-dependent atom-field coupling is discussed. The Hamiltonian for the atom-field system is written in terms of the elements of a closed algebra, which has SU(1,1) and Heisenberg-Weyl algebras as limiting cases. Eigenstates and eigenvalues of the Hamiltonian are constructed. With the field being in a coherent state initially, the dynamical behaviour of atomic-inversion, field-statistics and uncertainties in the field quadratures are studied. The appearance of nonclassical features during the evolution of the field is shown. Further, we explore the overlap of initial and time-evolved field states.

Abstract:
The states $|\alpha,m>$, defined as ${a^{\dagger}}^{m}|\alpha>$ up to a normalization constant and $m$ is a nonnegative integer, are shown to be the eigenstates of $f(\hat{n},m)\hat{a}$ where $f(\hat{n},m)$ is a nonlinear function of the number operator $\hat{n}$. The explicit form of $f(\hat{n},m)$ is constructed. The eigenstates of this operator for negative values of $m$ are introduced. The properties of these states are discussed and compared with those of the state $|\alpha,m >$.

Abstract:
We show that a class of even and odd nonlinear coherent states, defined as the eigenstates of product of a nonlinear function of the number operator and the square of the boson annihilation operator, can be generated in the center-of-mass motion of a trapped and bichromatically laser-driven ion. The nonclasscial properties of the states are studied.

Abstract:
A new hierarchy of separability conditions for bipartite states is obtained. All the conditions in the hierarchy are necessary for separability. The conditions are expressed in terms of higher powers of the density operator of the bipartite system and the reduced density operators of the subsystems. Violation of any of the conditions in the hierarchy implies entanglement. As a consequence of the hierarchy, another separability condition, expressed in terms of the eigenvalues of the density operators of the total system and subsystems, is obtained.

Abstract:
New quantal states which interpolate between the coherent states of the Heisenberg_Weyl and SU(1,1) algebras are introduced. The interpolating states are obtained as the coherent states of a closed and symmetric algebra which interpolates between the two algebras. The overcompleteness of the interpolating coherent states is established. Differential operator representations in suitable spaces of entire functions are given for the generators of the algebra. A nonsymmetric set of operators to realize the Heisenberg-Weyl algebra is provided and the relevant coherent states are studied.