Search results for " Inertia"
showing 10 items of 117 documents
INFLUENCE OF UNCERTAINTIES ON PD TUNING
2013
The aim of this work is to present a method for tuning the parameters of PD controller under the influences of the uncertainties, in order to stabilize the position of a rotor supported by active magnetic bearings (AMBs). The uncertainties are relative to mass, transverse and polar moment of inertia of the rotor. The introduction of the uncertainties is due to an incomplete modeled dynamic of the system or in the case the system being subjected to a parametric variation. The presence of the uncertainties produces a set of differences among the values of the output. Poles displacement method is used to reach the asymptotically stability condition characterized by a periodic oscillation durin…
Observation of an Intense Quasicontinuum of Superdeformed Rotational Transitions inEu143
1996
Quasicontinuum spectra in coincidence with transitions belonging to the different potential wells of {sup 143}Eu are studied with an increasing number of coincidence folds. An intense bump of rotationally correlated transitions is observed to develop in the high spin region. Fold distributions, angular anisotropies, moment of inertia determinations, and lower limits of lifetimes as a function of the rotational frequency show that the bump originates from highly collective rotationally damped {ital E}2 transitions generated by superdeformed states. {copyright} {ital 1996 The American Physical Society.}
Multidimensional Skyrme-density-functional Study of the Spontaneous Fission of 238U
2015
We determined the spontaneous fission lifetime of 238U by a minimization of the action integral in a three-dimensional space of collective variables. Apart from the mass-distribution multipole moments Q20 (elongation) and Q30 (left–right asymmetry), we also considered the pairing- fluctuation parameter λ2 as a collective coordinate. The collective potential was obtained self-consistently using the Skyrme energy density functional SkM∗ . The inertia tensor was obtained within the nonperturbative cranking approximation to the adiabatic time-dependent Hartree–Fock– Bogoliubov approach. The pairing-fluctuation parameter λ2 allowed us to control the pairing gap along the fission path, which sign…
Cluster rotational bands in 11B
2016
Differential cross-sections of 11B+α inelastic scattering at E(α) = 65 MeV leading to most of the known 11B states at excitation energies up to 14 MeV were measured [1]. The data analysis was done using Modified diffraction model (MDM) [2] allowing determining radii of excited states. Radii of the states with excitation energies less than ∼ 7 MeV coincide with the radius of the ground state with an accuracy not less than 0.1 - 0.15 fm. This result is consistent with traditional view on shell structure of low-lying states in 11B. Most of the observed high-energy excited states are distributed among four rotational bands. Moments of inertia of band states are close to the moment of inertia of…
Reference-point-independent dynamics of molecular liquids and glasses in the tensorial formalism.
2002
We apply the tensorial formalism to the dynamics of molecular liquids and glasses. This formalism separates the degrees of freedom into translational and orientational ones. Using the Mori-Zwanzig projection formalism, the equations of motion for the tensorial density correlators S(lmn,l'm'n')(q-->,t) are derived. For this we show how to choose the slow variables such that the resulting Mori-Zwanzig equations are covariant under a change of the reference point of the body fixed frame. We also prove that the memory kernels obtained from mode-coupling theory (MCT) including all approximations preserve the covariance. This covariance makes, e.g., the glass transition point, the two universal s…
Grid Stability Improvement Using Synthetic Inertia by Battery Energy Storage Systems in Small Islands
2022
In this paper, the synthetic inertia need of the small island of Pantelleria in the Mediterranean Sea is assessed. Firstly, the optimal renewable energy mix able to minimize the Levelized Cost of Energy for the generation system of the island is evaluated, considering the yearly load demand and the characteristics of the local natural resources. The optimal energy mix introduces in the island a quota of power generation with static power converters interfaced to the grid that could jeopardize the security of the system if not suitably controlled. Therefore, the inherent inertial response of the diesel generators of the system is calculated hour by hour for each month of one year, considerin…
Drift of the Earth’s Principal Axes of Inertia from GRACE and Satellite Laser Ranging Data
2020
The location of the Earth’s principal axes of inertia is a foundation for all the theories and solutions of its rotation, and thus has a broad effect on many fields, including astronomy, geodesy, and satellite-based positioning and navigation systems. That location is determined by the second-degree Stokes coefficients of the geopotential. Accurate solutions for those coefficients were limited to the stationary case for many years, but the situation improved with the accomplishment of Gravity Recovery and Climate Experiment (GRACE), and nowadays several solutions for the time-varying geopotential have been derived based on gravity and satellite laser ranging data, with time resolutions reac…
Unlocking behaviors of long-term service consumers : the role of action inertia
2017
Purpose The purpose of this paper is to examine the antecedents of word-of-mouth (WOM) in long-term service settings. Specifically, the authors examine the moderating role of action inertia in the relationships between satisfaction and repatronage intention, satisfaction and WOM, and repatronage intention and WOM. Design/methodology/approach The proposed model was empirically tested using survey data from 1,385 telecommunications service subscribers. The data were analyzed using partial least squares path modeling. Findings Results suggest that a positive link between repatronage intention and WOM, hereto a neglected relationship in the marketing literature, in contrast to previous literat…
A thermal inertia model for soil water content retrieval using thermal and multispectral images
2010
Soil moisture is difficult to quantify because of its high spatial variability. Consequently, great efforts have been undertaken by the research community to develop practical remote sensing approaches to estimate the spatial distribution of surface soil moisture over large areas and with high spatial detail. Many methodologies have been developed using remote sensing data acquiring information in different parts of the electromagnetic spectrum. Conventional field measurement techniques (including gravimetric and time-domain reflectometry) are point-based, involve on-site operators, are time expensive and, in any case, do not provide exhaustive information on the spatial distribution of soi…
Dynamic Control of Static Converters for the Transition from Grid-on to Grid-off Operation of AC/DC Microgrids
2022
In this paper, specific control logics defined for generators, controllable loads and electric energy storage systems are illustrated in order to improve the reliability of AC/DC hybrid microgrids in their grid-off operation following failure events such as short-circuits, line breaks, sudden disconnections of generating units or loads, etc. After defining specific control schemes, these were modelled in a digital environment and finally tested with dynamic simulations. Finally, the paper highlights the role of virtual synchronous machine control for the self-healing capacity of islanded hybrid microgrids.