The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Petros Maragos - One of the best experts on this subject based on the ideXlab platform.

  • Image demodulation using multidimensional Energy Separation
    Journal of the Optical Society of America A, 1995
    Co-Authors: Petros Maragos, Alan C. Bovik
    Abstract:

    Locally narrow-band images can be modeled as two-dimensional (2D) spatial AM–FM signals with several applications in image texture analysis and computer vision. We formulate an image-demodulation problem and present a solution based on the multidimensional Energy operator Φ(f) = ||∇f||2 − f∇2f. This nonlinear operator is a multidimensional extension of the one-dimensional (1D) Energy-tracking operator Ψ(f) = (f′)2 − ff″, which has been found useful for demodulating 1D AM–FM and speech signals. We discuss some interesting properties of the multidimensional operator and develop a multidimensional Energy-Separation algorithm to estimate the amplitude envelope and instantaneous frequencies of 2D spatially varying AM–FM signals. Experiments are also presented on applying this 2D Energy-demodulation algorithm to estimate the instantaneous amplitude contrast and spatial frequencies of image textures bandpass filtered by means of Gabor filters. The attractive features of the multidimensional Energy operator and the 2D Energy-Separation algorithm are their simplicity, efficiency, and ability to track instantaneously varying spatial-modulation patterns.

  • A system for finding speech formants and modulations via Energy Separation
    IEEE Transactions on Speech and Audio Processing, 1994
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    This correspondence presents an experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to automatically find speech formants and amplitude/frequency modulations in voiced speech segments. Initial estimates of formant center frequencies are provided by either LPC or morphological spectral peak picking. These estimates are then shown to be improved by a combination of bandpass filtering and iterative application of Energy Separation. >

  • DEMODULATION OF IMAGES MOD MODULATIONS USING MULTIDIlL ELED BY AMPLITUDE-FREQUENCY :ENSIONAL Energy Separation
    1994
    Co-Authors: Petros Maragos, Alan C. Bovik
    Abstract:

    Locally narrowband images can be modeled as 2D spatial AM-FM signals with several applications in image texture analysis and computer vision. In this paper we formulate such an image demodulation problem, and present a solution based on the multidimensional Energy operator @(f) = llVf112 - fV2 f. We discuss some interesting properties of this multidimensional operator and develop multidimensional Energy Separation algorithms to estimate the amplitude envelope and instantaneous frequencies of 2D spatially-varying AM-FM signals. Experiments are also presented on applying this 2D Energy demodulation algorithm to estimate the instantaneous amplitude contrast and spatial frequencies of image textures bandpass filtered via Gabor filters. The attractive features of the multidimensional Energy operator and the 2D Energy Separation algorithm are their simplicity, efficiency, and ability to track instantaneously-varying spatial modulation patterns.

  • Energy Separation in signal modulations with application to speech analysis
    IEEE Transactions on Signal Processing, 1993
    Co-Authors: Petros Maragos, J F Kaiser, Thomas F Quatieri
    Abstract:

    An efficient solution to the fundamental problem of estimating the time-varying amplitude envelope and instantaneous frequency of a real-valued signal that has both an AM and FM structure is provided. Nonlinear combinations of instantaneous signal outputs from the Energy operator are used to separate its output Energy product into its AM and FM components. The theoretical analysis is done first for continuous-time signals. Then several efficient algorithms are developed and compared for estimating the amplitude envelope and instantaneous frequency of discrete-time AM-FM signals. These Energy Separation algorithms are used to search for modulations in speech resonances, which are modeled using AM-FM signals to account for time-varying amplitude envelopes and instantaneous frequencies. The experimental results provide evidence that bandpass-filtered speech signals around speech formants contain amplitude and frequency modulations within a pitch period. >

  • ICASSP (2) - Finding speech formants and modulations via Energy Separation: with application to a vocoder
    IEEE International Conference on Acoustics Speech and Signal Processing, 1993
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    An experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to find speech formants and amplitude/frequency modulations automatically in voiced speech segments is presented. Initial estimates of formant center frequencies are provided by either LPC (linear predictive coding) or morphological spectral peak picking. These estimates are improved by a combination of bandpass filtering and iterative application of Energy Separation. The system is shown to be effective. Its application to an AM-FM vocoder is also discussed. >

Alexandros Potamianos - One of the best experts on this subject based on the ideXlab platform.

  • A system for finding speech formants and modulations via Energy Separation
    IEEE Transactions on Speech and Audio Processing, 1994
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    This correspondence presents an experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to automatically find speech formants and amplitude/frequency modulations in voiced speech segments. Initial estimates of formant center frequencies are provided by either LPC or morphological spectral peak picking. These estimates are then shown to be improved by a combination of bandpass filtering and iterative application of Energy Separation. >

  • ICASSP (2) - Finding speech formants and modulations via Energy Separation: with application to a vocoder
    IEEE International Conference on Acoustics Speech and Signal Processing, 1993
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    An experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to find speech formants and amplitude/frequency modulations automatically in voiced speech segments is presented. Initial estimates of formant center frequencies are provided by either LPC (linear predictive coding) or morphological spectral peak picking. These estimates are improved by a combination of bandpass filtering and iterative application of Energy Separation. The system is shown to be effective. Its application to an AM-FM vocoder is also discussed. >

Bo Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Experimental investigation of flow structure and Energy Separation of Ranque–Hilsch vortex tube with LDV measurement
    International Journal of Refrigeration, 2019
    Co-Authors: Xiangji Guo, Bo Zhang, Bo Liu
    Abstract:

    Abstract In this study, transparent vortex tubes of diameter 30 mm were designed for the main tube visualisation and a 2D laser Doppler velocimetry (LDV) measurement was adopted to investigate the mean flow field on the meridian plane. The distributions of the axial and radial velocities, and particularly the reverse flow boundary, were obtained for understanding the characteristics of large-scale vortex structures. Various operation conditions with different cold mass fractions (0.1–0.9), tube lengths (360 mm, 600 mm, and 900 mm), and inlet pressures (0.1 bar and 0.2 bar) were studied to reveal how the reverse flow boundary affects the Energy Separation performance. The LDV results show that the mean axial velocity distribution present good axial symmetry, and increasing the cold mass fraction results in an expansion of the reverse flow boundary as reported for previous numerical calculations. A deterioration in the Energy Separation performance due to an excessively short or long tube was revealed, and the proposed tube optimization criteria were proven.

  • computational investigation of precessing vortex breakdown and Energy Separation in a ranque hilsch vortex tube
    International Journal of Refrigeration-revue Internationale Du Froid, 2018
    Co-Authors: Bo Zhang
    Abstract:

    Abstract The flow structure and Energy Separation considering the effect of cold mass fraction in a Ranque–Hilsch vortex tube were investigated computationally based on the vortex breakdown theory. The velocity distributions and pressure fields for nine different cold mass fractions were considered. A quasi-cylindrical approximation was adopted to predict the size of the vortex core size by considering the pressure gradient. Further, a novel analysis was conducted on the Energy Separation mechanism, in which the large-scale vortex structure plays an important role; for example, increasing the cold mass fraction within a certain range can result in bigger vortex cores, yielding better Energy Separation performance. Finally, the type of vortex breakdown was also discussed for further understanding the vortex structure. This paper offers a new idea on the manner in which the external conditions (here, cold mass fraction) affect the large-scale vortex structure and on the subsequent Energy Separation performance.

  • Computational investigation of precessing vortex breakdown and Energy Separation in a Ranque–Hilsch vortex tube
    International Journal of Refrigeration, 2018
    Co-Authors: Xiangji Guo, Bo Zhang
    Abstract:

    Abstract The flow structure and Energy Separation considering the effect of cold mass fraction in a Ranque–Hilsch vortex tube were investigated computationally based on the vortex breakdown theory. The velocity distributions and pressure fields for nine different cold mass fractions were considered. A quasi-cylindrical approximation was adopted to predict the size of the vortex core size by considering the pressure gradient. Further, a novel analysis was conducted on the Energy Separation mechanism, in which the large-scale vortex structure plays an important role; for example, increasing the cold mass fraction within a certain range can result in bigger vortex cores, yielding better Energy Separation performance. Finally, the type of vortex breakdown was also discussed for further understanding the vortex structure. This paper offers a new idea on the manner in which the external conditions (here, cold mass fraction) affect the large-scale vortex structure and on the subsequent Energy Separation performance.

H.m. Hanson - One of the best experts on this subject based on the ideXlab platform.

  • A system for finding speech formants and modulations via Energy Separation
    IEEE Transactions on Speech and Audio Processing, 1994
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    This correspondence presents an experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to automatically find speech formants and amplitude/frequency modulations in voiced speech segments. Initial estimates of formant center frequencies are provided by either LPC or morphological spectral peak picking. These estimates are then shown to be improved by a combination of bandpass filtering and iterative application of Energy Separation. >

  • ICASSP (2) - Finding speech formants and modulations via Energy Separation: with application to a vocoder
    IEEE International Conference on Acoustics Speech and Signal Processing, 1993
    Co-Authors: H.m. Hanson, Petros Maragos, Alexandros Potamianos
    Abstract:

    An experimental system that uses an Energy-tracking operator and a related Energy Separation algorithm to find speech formants and amplitude/frequency modulations automatically in voiced speech segments is presented. Initial estimates of formant center frequencies are provided by either LPC (linear predictive coding) or morphological spectral peak picking. These estimates are improved by a combination of bandpass filtering and iterative application of Energy Separation. The system is shown to be effective. Its application to an AM-FM vocoder is also discussed. >

Mohammad O. Hamdan - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of vortex tube Energy Separation under different tube design
    Experimental Thermal and Fluid Science, 2018
    Co-Authors: Mohammad O. Hamdan, S A B Alomari, Ali S Oweimer
    Abstract:

    Abstract Through experimental investigation, this study offers a closer look into the performance of the vortex tube Energy Separation under different geometrical parameters; mainly tube length, diameter and internal tapering angle. Also the study evaluates the effect of inlet pressure on the performance of the vortex. The data shows that the tested vortex tube has an optimum length between 66 mm and 158 mm, an optimum diameter between 9 mm and 26 mm and a tapering angle smaller than 4°. Finally the experimental data show that the higher the inlet pressure, the greater the temperature difference however there is a maximum value where performance starts to deteriorate due to inlet nozzle choking.

  • Nozzle parameters affecting vortex tube Energy Separation performance
    Heat and Mass Transfer, 2013
    Co-Authors: Mohammad O. Hamdan, Basel Alsayyed, Emad Elnajjar
    Abstract:

    This experimental study reports the effect of nozzle parameters on the Energy Separation of the vortex tube. The results indicate that maximum Energy Separation is achieved with tangential nozzle orientation while the symmetry/asymmetry of nozzles has a minimal effect on the performance of the Energy Separation. For current selected conditions and parameters, the study shows that the optimum number of nozzles for maximum Energy Separation is around 4 nozzles.

  • Experimental analysis on vortex tube Energy Separation performance
    Heat and Mass Transfer, 2011
    Co-Authors: Mohammad O. Hamdan, Ahmed Alawar, Emad Elnajjar, Waseem Siddique
    Abstract:

    The present study reports the effect of several operating parameters on the thermal performance of the vortex tube. The experimental results indicate that the inlet pressure and the cold fraction are the most significant parameters influencing the vortex tube performance. The experimental data point out that insulation has minimal effect on the vortex tube performance. The same inlet pressure tests show that Energy Separation increases as number of inlet nozzle increases.