Design of Power System Stabilizer

A power system stabilizer (PSS) installed in the excitation system of the synchronous generator improves the small-signal power system stability by damping out low frequency oscillations in the power system. It does that by providing supplementary perturbation signals in a feedback path to the alternator excitation system. In our project we review different conventional PSS design (CPSS) techniques along with modern adaptive neuro-fuzzy design techniques. We adapt a linearized single-machine infinite bus model for design and simulation of the CPSS and the voltage regulator (AVR). We use 3 different input signals in the feedback (PSS) path namely, speed variation(w), Electrical Power (Pe), and integral of accelerating power (Pe*w), and review the results in each case. For simulations, we use three different linear design techniques, namely, root-locus design, frequency-response design, and pole placement design; and the preferred non-linear design technique is the adaptive neuro-fuzzy based controller design. The MATLAB package with Control System Toolbox and SIMULINK is used for the design and simulations

Relating the curvature of De Sitter Universe to Open Quantum Lamb Shift Spectroscopy

In this paper, we explore the connection between the curvature of the background De Sitter space-time with the spectroscopic study of entanglement of two atoms. Our set up is in the context of an Open Quantum System (OQS), where the two atoms, each having two energy levels and represented by Pauli spin tensor operators projected along any arbitrary direction. The system mimics the role of a pair of freely falling Unruh De-Witt detectors, which are allowed to non-adiabatically interact with a conformally coupled massless probe scalar field which has the role of background thermal bath. The effective dynamics of this combined system takes into account of the non-adiabatic interaction, which is commonly known as the Resonant Casimir Polder Interaction (RCPI) with the thermal bath. Our analysis reveals that the RCPI of two stable entangled atoms in the quantum vacuum states in OQS depends on the de Sitter space-time curvature relevant to the temperature of the thermal bath felt by the static observer. We also find that, in OQS, RCPI produces a new significant contribution appearing in the effective Hamiltonian of the total system and thermal bath under consideration. We find that the Lamb Shift is characterized by a decreasing inverse square power-law behavior, $L^{-2}$, when inter atomic Euclidean distance, $L$, is much larger than a characteristic length scale, $k$, which is the inverse surface gravity of the background De Sitter space. If the background space-time would have been Minkowskian this shift decreases as, $L^{-1}$, and is independent of temperature. Thus, we establish a connection between the curvature of the De Sitter space-time with the Lamb Shift spectroscopy.Comment: 65 pages, 3 figures, 1 Table, This project is the part of the non-profit virtual international research consortium "Quantum Structures of the Space-Time & Matter". Accepted for publication in European Physical Journal

QMetrology from QCosmology: Study with Entangled Two Qubit Open Quantum System in De Sitter Space

In this paper, our prime objective is to apply the techniques of parameter estimation theory and the concept of Quantum Metrology in the form of Fisher Information to investigate the role of certain physical quantities in the open quantum dynamics of a two entangled qubit system under the Markovian approximation. There exist various physical parameters which characterize such system, but can not be treated as any quantum mechanical observable. It becomes imperative to do a detailed parameter estimation analysis to determine the physically consistent parameter space of such quantities. We apply both Classical Fisher Information (CFI) and Quantum Fisher Information (QFI) to correctly estimate these parameters, which play significant role to describe the out-of-equilibrium and the long range quantum entanglement phenomena of open quantum system. Quantum Metrology, compared to classical parameter estimation theory, plays a two-fold superior role, improving the precision and accuracy of parameter estimation. Additionally, in this paper we present a new avenue in terms of Quantum Metrology, which beats the classical parameter estimation. We also present an interesting result of revival of out-of-equilibrium feature at the late time scales, arising due to the long range quantum entanglement at early time scale and provide a physical interpretation for the same in terms of Bell's Inequality Violation in early time scale giving rise to non-locality.Comment: 14 pages, 9 figures, This project is the part of the non-profit virtual international research consortium "Quantum Structures of the Space-Time and Matter (QASTM)", Revised version, Accepted for publication in SciPost Physics Cor

Indirect detection of Cosmological Constant from interacting open quantum system

We study the indirect detection of Cosmological Constant from an open quantum system of interacting spins, weakly interacting with a thermal bath, a massless scalar field minimally coupled with the static de Sitter background, by computing the spectroscopic shifts. By assuming pairwise interaction between spins, we construct states using a generalisation of the superposition principle. The corresponding spectroscopic shifts, caused by the effective Hamiltonian of the system due to Casimir Polder interaction, are seen to play a crucial role in predicting a very tiny value of the Cosmological Constant, in the static patch of de Sitter space, which is consistent with the observed value from the Planck measurements of the cosmic microwave background (CMB) anisotropies.Comment: 27 pages, 7 figures, This project is the part of the non-profit virtual international research consortium "Quantum Structures of the Space-Time & Matter (QASTM)", Updated versio

Circuit Complexity From Cosmological Islands

Recently in various theoretical works, path-breaking progress has been made in recovering the well-known Page Curve of an evaporating black hole with Quantum Extremal Islands, proposed to solve the long-standing black hole information loss problem related to the unitarity issue. Motivated by this concept, in this paper, we study cosmological circuit complexity in the presence (or absence) of Quantum Extremal Islands in the negative (or positive) Cosmological Constant with radiation in the background of Friedmann-Lema$\hat{i}$tre-Robertson-Walker (FLRW) space-time i.e the presence and absence of islands in anti-de Sitter and the de Sitter spacetime having SO(2, 3) and SO(1, 4) isometries respectively. Without using any explicit details of any gravity model, we study the behaviour of the circuit complexity function with respect to the dynamical cosmological solution for the scale factors for the above-mentioned two situations in FLRW space-time using squeezed state formalism. By studying the cosmological circuit complexity, Out-of-Time Ordered Correlators, and entanglement entropy of the modes of the squeezed state, in different parameter spaces, we conclude the non-universality of these measures. Their remarkably different features in the different parameter spaces suggest their dependence on the parameters of the model under consideration.Comment: 75 pages, 29 figures, 4 tables, Dr. Sayantan Choudhury would like to dedicate this work to his lovable father and prime inspiration Professor Manoranjan Choudhury who recently have passed away due to COVID 19. Updated and revised version, Accepted for publication in Symmetry (section: Physics and Symmetry/Asymmetry, Special issue: Manifest and Hidden Symmetries in Field and String Theories

Relating the curvature of De Sitter universe to open quantum lamb shift spectroscopy

In this paper, our prime objective is to connect the curvature of our observable De Sitter Universe with the spectroscopic study of entanglement of two atoms in an open quantum system (OQS). The OQS considered in our work is made up of two atoms which are represented by Pauli spin tensor operators projected along any arbitrary direction. They mimic the role of a pair of freely falling Unruh De-Witt detectors, which are allowed to non-adiabatically interact with a conformally coupled massless probe scalar field in the De Sitter background. The effective dynamics of the atomic detectors are actually an outcome of their non-adiabatic interaction, which is commonly known as the Resonant Casimir Polder Interaction (RCPI) with the thermal bath. We find from our analysis that the RCPI of two stable entangled atoms in the quantum vacuum states in OQS depends on the De Sitter space-time curvature relevant to the temperature of the thermal bath felt by the static observer. We also find that, in OQS, RCPI produces a new significant contribution appearing in the effective Hamiltonian of the total system and thermal bath under consideration. This will finally give rise to Lamb Spectroscopic Shift, as appearing in the context of atomic and molecular physics. This analysis actually plays a pivotal role to make the bridge between the geometry of our observed Universe to the entanglement in OQS through Lamb Shift atomic spectroscopy. Thus, we are strongly aiming to connect the curvature of the background space-time of our Universe to open quantum Lamb Shift spectroscopy by measuring the quantum properties of a two entangled OQS in the atomic experiment.by Abinash Swain et al

Pushing Boundaries in Single Molecule Magnets: An Ab Initio Perspective on Harnessing Unusual Oxidation States for Unprecedented Lanthanide SMM Performance

The recent breakthrough of attaining blocking temperature near liquid N2 temperature rekindled the interest in lanthanide-based Single Molecule Magnets towards end-user applications. Within this realm, several challenges are present, with a key objective being the further enhancement of the blocking temperature. As the current set of molecules based on Dy(III) has already reached their maximum potential barrier height for magnetization reversal (Ueff), chemical insights-based developments are hampered. In this connection, using DFT and ab initio CASSCF methods, we have explored the possibility of obtaining lanthanide SMMs in unusual oxidation states such as +4 and +5. We are encouraged by the fact that several such complexes are already reported, with some of them found to exhibit performant SMM characteristics. We begin with various small models of [LnO2], [LnO2]−, and [LnO2]+ (Ln varying from Ce to Lu) systems to correlate the nature of the lanthanides to the SMM characteristics. We have also extended our study to include five complexes reported earlier possessing +4 and +5 oxidation states to offer clues to improve the SMM characteristics. Our calculations reveal several advantages in fine-tuning the oxidation state in lanthanide SMMs, and this includes (i) the lanthanide-ligand covalency found to increase as high as 45% compared to the LnIII counterpart (ii) yield barrier height for magnetization reversal as high as 8500 cm-1, an unprecedented tuning up to three times larger compared to the best-in-class LnIII counterpart (iii) among various ways to stabilise such high-oxidation state including encapsulation yield several targets with HoO2@SWCNT(4,4) predicted to yield an impressive energy barrier of ~5400 cm−1 (iv) the stronger lanthanide-ligand bonds also found to help in tuning the spin-phonon relaxation as stronger bonds found to offset the vibrations that cause the relaxation, potentially yield larger blocking temperatures - offering a never-before-seen strategy to new class lanthanide SMMs

Extended liaison as an interface between product and process model in assembly

This paper describes the use of liaison to better integrate product model and assembly process model so as to enable sharing of design and assembly process information in a common integrated form and reason about them. Liaison can be viewed as a set, usually a pair, of features in proximity with which process information can be associated. A liaison is defined as a set of geometric entities on the parts being assembled and relations between these geometric entities. Liaisons have been defined for riveting, welding, bolt fastening, screw fastening, adhesive bonding (gluing) and blind fastening processes. The liaison captures process specific information through attributes associated with it. The attributes are associated with process details at varying levels of abstraction. A data structure for liaison has been developed to cluster the attributes of the liaison based on the level of abstraction. As information about the liaisons is not explicitly available in either the part model or the assembly model, algorithms have been developed for extracting liaisons from the assembly model. The use of liaison is proposed to enable both the construction of process model as the product model is fleshed out, as well as maintaining integrity of both product and process models as the inevitable changes happen to both design and the manufacturing environment during the product lifecycle. Results from aerospace and automotive domains have been provided to illustrate and validate the use of liaisons. (C) 2014 Elsevier Ltd. All rights reserved

A Machine Learning Approach to Decipher the Origin of Magnetic Anisotropy in Three-Coordinate Cobalt Single-Ion Magnets

Single Molecule Magnets (SMMs) emulate permanent magnets and are highly regarded for their role in compact information storage and molecular spintronics. Their behavior is primarily governed by magnetic anisotropy, expressed through parameters like the axial zero-field splitting (D) and orientation of magnetic anisotropy (gx, gy, gz) in mononuclear transition metal complexes. Low-coordinate mononuclear transition metal complexes stand out for their substantial anisotropy and higher blocking temperatures. However, understanding the intricate interplay between these parameters poses a significant challenge, often beyond traditional magneto-structural correlations. Hence, machine learning (ML) tools have been embraced to address these complexities. By employing an ML model based on Co-ligand bond length and angle relative to the pseudo-C3 axis, this study effectively rationalizes variations in D values, g-factors, and rhombic anisotropy, crucial for determining magnetic properties. Leveraging a dataset of 627 molecules, the research explores ML\u27s potential in predicting magnetic anisotropy parameters in three-coordinate Co(II) complexes, achieving a minimal mean absolute error (MAE) of approximately 17 cm⁻¹ and high accuracy levels exceeding 95% for classification tasks. These insights offer valuable guidance for the development of innovative single-ion magnets