The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform

M Saidy - One of the best experts on this subject based on the ideXlab platform.

  • a unified approach to voltage regulator and power system stabiliser design based on predictive control in Analogue Form
    International Journal of Electrical Power & Energy Systems, 1997
    Co-Authors: M Saidy
    Abstract:

    Abstract A unified approach for voltage regulator and power system stabiliser design based on predictive control in the s domain is presented in this paper. The proposed controller employs the current and voltage components along the d and q axis, I d , I q , V d , as additional control signals. The aim is to solve the conflicting demands of the control requirements of generator terminal voltage regulation and damping of electrical power oscillations. In the time domain, the results obtained have shown that the Analogue predictive controller with fixed structure and parameters provides, unlike the conventional excitation control scheme (voltage regulator and power system stabiliser), a good consistent perFormance for cases of strong, as well as weak, tie line connection of the generator with the grid system.

Aki Cellatoglu - One of the best experts on this subject based on the ideXlab platform.

  • Vibrating Cantilever Transducer Incorporated in Dual Diaphragms Structure for Sensing Differential Pneumatic Pressure
    2012
    Co-Authors: Aki Cellatoglu
    Abstract:

    Pneumatic pressure cells with thin metallic spherical diaphragm of shallow spherical shell configuration linked with vibrating wire pickup or vibrating cantilever pickup were reported in the past. In order to enhance the sensitivity of the pressure cell this work considers dual diaphragm structure fitted with cantilever pickup. The design and development of the pressure cell with this dual diaphragm structure having cantilever pickup is presented here. The geometrical design is optimally made as to sense either mono pressure or differential pressure resources. The cantilevers of the two diaphragms are excited to produce vibrations and the frequencies of vibrations are determined by picking up signals from orthogonally arranged opto-coupler links. With the computed frequency a lookup table is referred to obtain the pressure acting on the concerned diaphragm. In the external circuits, the average pressure and the differential pressure acting on two diaphragms are computed. Furthermore transmitting circuits taking the average pressure and differential pressure in digital Form and Analogue Form to remote area are presented. PerFormance analysis of the proposed mechatronic pressure cell is made and its improved perFormance over other pressure cells is presented. KEYWORDS Cantilever excitation, diaphragm with cantilever, differential pressure transducer, dual diaphragm cell, pressure transmitter 1

  • vibrating cantilever transducer incorporated in dual diaphragms structure for sensing differential pneumatic pressure
    International Journal of Soft Computing, 2011
    Co-Authors: Aki Cellatoglu, Alasubramania Karuppana
    Abstract:

    Pneumatic pressure cells with thin metallic spherical diaphragm of shallow spherical shell configuration linked with vibrating wire pickup or vibrating cantilever pickup were reported in the past. In order to enhance the sensitivity of the pressure cell this work considers dual diaphragm structure fitted with cantilever pickup. The design and development of the pressure cell with this dual diaphragm structure having cantilever pickup is presented here. The geometrical design is optimally made as to sense either mono pressure or differential pressure resources. The cantilevers of the two diaphragms are excited to produce vibrations and the frequencies of vibrations are determined by picking up signals from orthogonally arranged opto-coupler links. With the computed frequency a lookup table is referred to obtain the pressure acting on the concerned diaphragm. In the external circuits, the average pressure and the differential pressure acting on two diaphragms are computed. Furthermore transmitting circuits taking the average pressure and differential pressure in digital Form and Analogue Form to remote area are presented. PerFormance analysis of the proposed mechatronic pressure cell is made and its improved perFormance over other pressure cells is presented.

Jiri Koziorek - One of the best experts on this subject based on the ideXlab platform.

  • PDeS - Using Methodology for MATLAB Designing the First-Order Chebyshev Analogue and IIR Digital Filters
    IFAC Proceedings Volumes, 2012
    Co-Authors: Petr Vojcinak, Martin Pies, Jiri Koziorek
    Abstract:

    This paper deals with using some MATLAB functions and tools for designing the first-order Analogue Chebyshev filters and IIR Chebyshev filters. The first part of this paper is focused on a design of an Analogue filter via Chebyshev approximation approach, including features and mathematical background of this iso-extremal approximation, approximation of a normalized low-pass (NLP) filter, and some mathematical Formulas for calculating its fundamental parameters, such as constructing a tolerance scheme, an order of the Chebyshev approximation, poles of the NLP's transfer function, characteristic equation, and group delay. Due to some frequency transFormation Formulas implemented in MATLAB, un-normalized Forms of frequency functions for low-pass (LP), high-pass (HP), band-pass (BP), and band-stop (BS) Analogue filters are also available. The second part of this paper describes a design of the first-order IIR Chebyshev filter via Filter Visualization Tool (FVT), and functions, implemented in Signal Processing Toolbox, whereas a conversion from the Analogue Form into the digital Form is done and discussed for bilinear transFormation only.

  • using methodology for matlab designing the first order chebyshev Analogue and iir digital filters
    Programmable Devices and Embedded Systems, 2012
    Co-Authors: Petr Vojcinak, Martin Pies, Jiri Koziorek
    Abstract:

    This paper deals with using some MATLAB functions and tools for designing the first-order Analogue Chebyshev filters and IIR Chebyshev filters. The first part of this paper is focused on a design of an Analogue filter via Chebyshev approximation approach, including features and mathematical background of this iso-extremal approximation, approximation of a normalized low-pass (NLP) filter, and some mathematical Formulas for calculating its fundamental parameters, such as constructing a tolerance scheme, an order of the Chebyshev approximation, poles of the NLP's transfer function, characteristic equation, and group delay. Due to some frequency transFormation Formulas implemented in MATLAB, un-normalized Forms of frequency functions for low-pass (LP), high-pass (HP), band-pass (BP), and band-stop (BS) Analogue filters are also available. The second part of this paper describes a design of the first-order IIR Chebyshev filter via Filter Visualization Tool (FVT), and functions, implemented in Signal Processing Toolbox, whereas a conversion from the Analogue Form into the digital Form is done and discussed for bilinear transFormation only.

Jérôme Antoni - One of the best experts on this subject based on the ideXlab platform.

  • Rolling Element Bearing Diagnostics - A Tutorial
    Mechanical Systems and Signal Processing, 2011
    Co-Authors: Robert B. Randall, Jérôme Antoni
    Abstract:

    This tutorial is intended to guide the reader in the diagnostic analysis of acceleration signals from rolling element bearings, in particular in the presence of strong masking signals from other machine components such as gears. Rather than being a review of all the current literature on bearing diagnostics, its purpose is to explain the background for a very powerful procedure which is successful in the majority of cases. The latter contention is illustrated by the application to a number of very different case histories, from very low speed to very high speed machines. The specific characteristics of rolling element bearing signals are explained in great detail, in particular the fact that they are not periodic, but stochastic, a fact which allows them to be separated from deterministic signals such as from gears. They can be modelled as cyclostationary for some purposes, but are in fact not strictly cyclostationary (at least for localised defects) so the term pseudo-cyclostationary has been coined. An appendix on cyclostationarity is included. A number of techniques are described for the separation, of which the discrete/random separation (DRS) method is usually most efficient. This sometimes requires the effects of small speed fluctuations to be removed in advance, which can be achieved by order tracking, and so this topic is also amplified in an appendix. Signals from localised faults in bearings are impulsive, at least at the source, so techniques are described to identify the frequency bands in which this impulsivity is most marked, using spectral kurtosis. For very high speed bearings, the impulse responses elicited by the sharp impacts in the bearings may have a comparable length to their separation, and the minimum entropy deconvolution technique may be found useful to remove the smearing effects of the (unknown) transmission path. The final diagnosis is based on "envelope analysis" of the optimally filtered signal, but despite the fact that this technique has been used for 40 years in Analogue Form, the advantages of more recent digital implementations are explained.

Militzer Burkhard - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of Chlorine and Fluorine Crystal Structures at High Pressure Using Symmetry Driven Structure Search with Geometric Constraints
    2020
    Co-Authors: Olson, Mark A., Bhatia Shefali, Larson Paul, Militzer Burkhard
    Abstract:

    The high-pressure properties of fluorine and chlorine are not yet well understood because both are highly reactive and volatile elements, which has made conducting diamond anvil cell and x-ray diffraction experiments a challenge. Here we use ab initio methods to search for stable crystal structures of both elements at megabar pressures. We demonstrate how symmetry and geometric constraints can be combined to efficiently generate crystal structures that are composed of diatomic molecules. Our algorithm extends the symmetry driven structure search method [Phys. Rev. B 98 (2018) 174107] by adding constraints for the bond length and the number of atoms in a molecule, while still maintaining generality. As a method of validation, we have tested our approach for dense hydrogen and reproduced the known molecular structures of Cmca-12 and Cmca-4. We apply our algorithm to study chlorine and fluorine in the pressure range from 10--4000 GPa while considering crystal structures with up to 40 atoms per unit cell. We predict chlorine to follow the same series of phase transFormations as elemental iodine from Cmca to Immm to Fm$\bar{3}$m, but at substantially higher pressures. We predict fluorine to transition from a C2/c to an Cmca structure at 70 GPa, to a novel orthorhombic and metallic structure with P$4_2$/mmc symmetry at 2500 GPa, and finally into its cubic Analogue Form with Pm$\bar{3}$n symmetry at 3000 GPa.Comment: 9 pages, 7 figure