The Experts below are selected from a list of 13371 Experts worldwide ranked by ideXlab platform
Paul A Johnson - One of the best experts on this subject based on the ideXlab platform.
-
pump and probe waves in dynamic acousto elasticity comprehensive description and comparison with nonlinear elastic theories
Journal of Applied Physics, 2013Co-Authors: Julie Riviere, Guillaume Renaud, R A Guyer, Paul A JohnsonAbstract:Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the Harmonic Content. Amplitude dependences of the Harmonic Content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for Harmonics l...
-
pump and probe waves in dynamic acousto elasticity comprehensive description and comparison with nonlinear elastic theories
Journal of Applied Physics, 2013Co-Authors: Julie Riviere, Guillaume Renaud, R A Guyer, Paul A JohnsonAbstract:Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the Harmonic Content. Amplitude dependences of the Harmonic Content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for Harmonics larger than the second and for strains larger than 10−6. This observation is related to the phenomenon of acoustic conditioning that brings the material to a metastable state for each new excitation amplitude. Analysis of the steady-state regime provides additional information regarding acoustic conditioning, i.e., a progressive decrease of the amplitude of odd Harmonics during excitation time with a log(t)-dependence. This observation confirms that the Harmonic Content is affected by the conditioning. Experimental challenges addressed include the fact that the compressional mode used for DAE can be affected by bending/torsion modes: their influence is evaluated, and guidances are given to minimize effects.
A. Tani - One of the best experts on this subject based on the ideXlab platform.
-
reduction of the input current Harmonic Content in matrix converters under input output unbalance
IEEE Transactions on Industrial Electronics, 1998Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:This paper deals with the performance evaluation of space-vector-modulated matrix power converters under input and output unbalanced conditions. Two control strategies of the input current displacement angle are presented and compared in order to emphasize their influence on the input current Harmonic Content. The first is based on keeping the input current vector in phase with the input voltage vector. In the second, the input current displacement angle is dynamically modulated as a function of positive- and negative-sequence components of the input voltages. In both cases, the Harmonic Content and the three-phase RMS value of the input current have been evaluated analytically. The input current Harmonic spectrum is quite different for the two control strategies and can be related to the input and output unbalance. It has been verified that, in the usual case of balanced output conditions, using the second method, it is possible to eliminate the Harmonic components of the input current. Some numerical simulations are presented to confirm the analytical results.
-
a general approach for the analysis of the input power quality in matrix converters
Power Electronics Specialists Conference, 1996Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:In this paper, a general approach based on a linearized analysis is employed in order to determine the matrix converter performance in terms of input-current quality. Considering input disturbances such as voltage unbalance and voltage distortion as a linear deviation from the fundamental Harmonic component, it is possible to evaluate analytically the input-current Harmonic Content. It is emphasized that the input-current frequency spectrum is affected by the input-current modulation strategy employed. By using an optimal dynamic modulation strategy, it is possible to minimize the input-current Harmonic Content. Some numerical results are given to confirm the analytical solutions.
-
reduction of the input current Harmonic Content in matrix converters under input output unbalance
Conference of the Industrial Electronics Society, 1995Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:This paper deals with the performance evaluation of space vector modulation controlled matrix power converters under input and output unbalanced conditions. Two control strategies are presented and compared with reference to the input current Harmonic Content. The first strategy is based on keeping the input current vector in phase with the input voltage vector. In the second strategy, the input current vector is modulated along a direction depending on positive and negative sequence components of the input voltages. In both cases, the Harmonic Content of the input current has been evaluated analytically. It has been verified that the input current Harmonic spectrum is quite different for the two control strategies and can be related to the input and output unbalance. Some numerical simulation are presented to confirm the analytical results.
Julie Riviere - One of the best experts on this subject based on the ideXlab platform.
-
pump and probe waves in dynamic acousto elasticity comprehensive description and comparison with nonlinear elastic theories
Journal of Applied Physics, 2013Co-Authors: Julie Riviere, Guillaume Renaud, R A Guyer, Paul A JohnsonAbstract:Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the Harmonic Content. Amplitude dependences of the Harmonic Content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for Harmonics l...
-
pump and probe waves in dynamic acousto elasticity comprehensive description and comparison with nonlinear elastic theories
Journal of Applied Physics, 2013Co-Authors: Julie Riviere, Guillaume Renaud, R A Guyer, Paul A JohnsonAbstract:Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the Harmonic Content. Amplitude dependences of the Harmonic Content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for Harmonics larger than the second and for strains larger than 10−6. This observation is related to the phenomenon of acoustic conditioning that brings the material to a metastable state for each new excitation amplitude. Analysis of the steady-state regime provides additional information regarding acoustic conditioning, i.e., a progressive decrease of the amplitude of odd Harmonics during excitation time with a log(t)-dependence. This observation confirms that the Harmonic Content is affected by the conditioning. Experimental challenges addressed include the fact that the compressional mode used for DAE can be affected by bending/torsion modes: their influence is evaluated, and guidances are given to minimize effects.
Domenico Casadei - One of the best experts on this subject based on the ideXlab platform.
-
reduction of the input current Harmonic Content in matrix converters under input output unbalance
IEEE Transactions on Industrial Electronics, 1998Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:This paper deals with the performance evaluation of space-vector-modulated matrix power converters under input and output unbalanced conditions. Two control strategies of the input current displacement angle are presented and compared in order to emphasize their influence on the input current Harmonic Content. The first is based on keeping the input current vector in phase with the input voltage vector. In the second, the input current displacement angle is dynamically modulated as a function of positive- and negative-sequence components of the input voltages. In both cases, the Harmonic Content and the three-phase RMS value of the input current have been evaluated analytically. The input current Harmonic spectrum is quite different for the two control strategies and can be related to the input and output unbalance. It has been verified that, in the usual case of balanced output conditions, using the second method, it is possible to eliminate the Harmonic components of the input current. Some numerical simulations are presented to confirm the analytical results.
-
a general approach for the analysis of the input power quality in matrix converters
Power Electronics Specialists Conference, 1996Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:In this paper, a general approach based on a linearized analysis is employed in order to determine the matrix converter performance in terms of input-current quality. Considering input disturbances such as voltage unbalance and voltage distortion as a linear deviation from the fundamental Harmonic component, it is possible to evaluate analytically the input-current Harmonic Content. It is emphasized that the input-current frequency spectrum is affected by the input-current modulation strategy employed. By using an optimal dynamic modulation strategy, it is possible to minimize the input-current Harmonic Content. Some numerical results are given to confirm the analytical solutions.
-
reduction of the input current Harmonic Content in matrix converters under input output unbalance
Conference of the Industrial Electronics Society, 1995Co-Authors: Domenico Casadei, G. Serra, A. TaniAbstract:This paper deals with the performance evaluation of space vector modulation controlled matrix power converters under input and output unbalanced conditions. Two control strategies are presented and compared with reference to the input current Harmonic Content. The first strategy is based on keeping the input current vector in phase with the input voltage vector. In the second strategy, the input current vector is modulated along a direction depending on positive and negative sequence components of the input voltages. In both cases, the Harmonic Content of the input current has been evaluated analytically. It has been verified that the input current Harmonic spectrum is quite different for the two control strategies and can be related to the input and output unbalance. Some numerical simulation are presented to confirm the analytical results.
Fabrizio Marignetti - One of the best experts on this subject based on the ideXlab platform.
-
pole shape based reduction of the Harmonic Content of the ipm t lsm air gap flux density
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Amal Souissi, Imen Abdennadher, Roberto Di Stefano, Ahmed Masmoudi, Fabrizio MarignettiAbstract:This paper presents a sizing approach dedicated to the reduction of the Harmonic Content of the air gap flux density of interior permanent magnet tubular-linear synchronous machines (IPM T-LSMs) based on pole shaping. The study is initiated by a formulation of the air gap flux density of conventional IPM T-LSMs equipped with flat-shaped poles. In the second step, the established model is reformulated with emphasis on the pole shape variation characterized by two parameters: the pole air gap radial width and the pole head opening. Following its experimental validation, the resulting model is applied to the sizing of the pole shape in an attempt to reduce the Harmonic Content of the air gap flux density. The developed sizing procedure considers the effect of the above-defined parameters on the Harmonic Content of both the radial and axial components of the air gap flux density. The study is achieved by the selection of a set of parameters for which both radial and axial components of the air gap flux density exhibit their lowest spatial Harmonic distortion.
