The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform

B. Renou - One of the best experts on this subject based on the ideXlab platform.

  • measurement of laminar burning velocity and markstein length relative to fresh gases using a new postprocessing Procedure Application to laminar spherical flames for methane ethanol and isooctane air mixtures
    Combustion and Flame, 2012
    Co-Authors: Emilien Varea, Alexis Vandel, Vincent Modica, B. Renou
    Abstract:

    Abstract The purpose of this study is to present a new tool for extracting the laminar burning velocity in the case of spherically outward expanding flames. This new Procedure makes it possible to determine the laminar burning velocity directly based on the flame displacement speed and the global fresh gas velocity near the preheat zone of the flame front. It therefore presents a very interesting alternative to the standard method (commonly used in the literature), which is based on the flame front displacement and the ratio of unburned and burned gas densities. The influence of external flame stretching on the burning velocity can be characterized and the Markstein length relative to the unburned gases (i.e., fresh gases) can be deduced by using this new tool. Contrary to the standard Procedure, the unstretched laminar burning velocity is determined directly without using the fuel mixture properties. The temporal evolution of the flame front is visualized by high-speed laser tomography and the algorithm, based on a tomographic image correlation method, makes it possible to accurately measure the fresh gas velocity near the preheat zone of the flame front. The measurements of laminar flame speeds are carried out in a high-pressure and high-temperature constant-volume vessel over a wide range of equivalence ratios for methane, ethanol, and isooctane/air mixtures. To validate the experimental facility and the postprocessing of the flame images, fresh gas velocities and unstretched laminar burning velocities, as well as Markstein lengths relative to burned and unburned gases, are presented and compared with experimental and numerical results of the literature for methane/air flames. New results concerning ethanol/air and isooctane/air flames are presented for various experimental conditions (373 K, equivalence ratios range 0.7–1.5, pressure range 0.1–5 MPa).

  • Measurement of laminar burning velocity and Markstein length relative to fresh gases using a new postprocessing Procedure: Application to laminar spherical flames for methane, ethanol and isooctane/air mixtures
    Combustion and Flame, 2012
    Co-Authors: Emilien Varea, Alexis Vandel, Vincent Modica, B. Renou
    Abstract:

    The purpose of this study is to present a new tool for extracting the laminar burning velocity in the case of spherically outward expanding flames. This new Procedure makes it possible to determine the laminar burning velocity directly based on the flame displacement speed and the global fresh gas velocity near the preheat zone of the flame front. It therefore presents a very interesting alternative to the standard method (commonly used in the literature), which is based on the flame front displacement and the ratio of unburned and burned gas densities. The influence of external flame stretching on the burning velocity can be characterized and the Markstein length relative to the unburned gases (i.e., fresh gases) can be deduced by using this new tool. Contrary to the standard Procedure, the unstretched laminar burning velocity is determined directly without using the fuel mixture properties. The temporal evolution of the flame front is visualized by high-speed laser tomography and the algorithm, based on a tomographic image correlation method, makes it possible to accurately measure the fresh gas velocity near the preheat zone of the flame front. The measurements of laminar flame speeds are carried out in a high-pressure and high-temperature constant-volume vessel over a wide range of equivalence ratios for methane, ethanol, and isooctane/air mixtures. To validate the experimental facility and the postprocessing of the flame images, fresh gas velocities and unstretched laminar burning velocities, as well as Markstein lengths relative to burned and unburned gases, are presented and compared with experimental and numerical results of the literature for methane/air flames. New results concerning ethanol/air and isooctane/air flames are presented for various experimental conditions (373. K, equivalence ratios range 0.7-1.5, pressure range 0.1-5. MPa). © 2011 The Combustion Institute.

Leticia Andrade - One of the best experts on this subject based on the ideXlab platform.

  • doubleslicing a non iterative single profile multi exponential curve resolution Procedure Application to time domain nmr transverse relaxation data
    Journal of Magnetic Resonance, 2007
    Co-Authors: Leticia Andrade, Elisabeth Micklander, Imad A Farhat, Soren Balling Engelsen
    Abstract:

    Abstract A new non-iterative curve resolution technique for resolving single decay profiles is proposed. The new technique, called DoubleSlicing , is based on the Decra (Direct Exponential Curve Resolution Algorithm) principle. While the original Decra was designed to resolve several decay curves simultaneously and thus fitting common pure exponentials, DoubleSlicing can resolve single decay profiles by a simple double data transformation followed by an analytical and unique three-way decomposition. The new approach is successfully demonstrated on experimental NMR CPMG relaxation data, measured on combinations of unmixed paramagnetic CuSO 4 solutions. Decay signals of the water component were acquired following an innovative experimental design that ensured no interaction between the components present in each sample under observation. DoubleSlicing proved to be accurate in estimating relaxation times differing in one order of magnitude (range: 19.6–159.4 ms). Its performance was comparable to discrete exponential fitting with the advantage of being much faster – in terms of computation time, DoubleSlicing outperformed exponential fitting by a factor of four.

Soren Balling Engelsen - One of the best experts on this subject based on the ideXlab platform.

  • doubleslicing a non iterative single profile multi exponential curve resolution Procedure Application to time domain nmr transverse relaxation data
    Journal of Magnetic Resonance, 2007
    Co-Authors: Leticia Andrade, Elisabeth Micklander, Imad A Farhat, Soren Balling Engelsen
    Abstract:

    Abstract A new non-iterative curve resolution technique for resolving single decay profiles is proposed. The new technique, called DoubleSlicing , is based on the Decra (Direct Exponential Curve Resolution Algorithm) principle. While the original Decra was designed to resolve several decay curves simultaneously and thus fitting common pure exponentials, DoubleSlicing can resolve single decay profiles by a simple double data transformation followed by an analytical and unique three-way decomposition. The new approach is successfully demonstrated on experimental NMR CPMG relaxation data, measured on combinations of unmixed paramagnetic CuSO 4 solutions. Decay signals of the water component were acquired following an innovative experimental design that ensured no interaction between the components present in each sample under observation. DoubleSlicing proved to be accurate in estimating relaxation times differing in one order of magnitude (range: 19.6–159.4 ms). Its performance was comparable to discrete exponential fitting with the advantage of being much faster – in terms of computation time, DoubleSlicing outperformed exponential fitting by a factor of four.

Emilien Varea - One of the best experts on this subject based on the ideXlab platform.

  • measurement of laminar burning velocity and markstein length relative to fresh gases using a new postprocessing Procedure Application to laminar spherical flames for methane ethanol and isooctane air mixtures
    Combustion and Flame, 2012
    Co-Authors: Emilien Varea, Alexis Vandel, Vincent Modica, B. Renou
    Abstract:

    Abstract The purpose of this study is to present a new tool for extracting the laminar burning velocity in the case of spherically outward expanding flames. This new Procedure makes it possible to determine the laminar burning velocity directly based on the flame displacement speed and the global fresh gas velocity near the preheat zone of the flame front. It therefore presents a very interesting alternative to the standard method (commonly used in the literature), which is based on the flame front displacement and the ratio of unburned and burned gas densities. The influence of external flame stretching on the burning velocity can be characterized and the Markstein length relative to the unburned gases (i.e., fresh gases) can be deduced by using this new tool. Contrary to the standard Procedure, the unstretched laminar burning velocity is determined directly without using the fuel mixture properties. The temporal evolution of the flame front is visualized by high-speed laser tomography and the algorithm, based on a tomographic image correlation method, makes it possible to accurately measure the fresh gas velocity near the preheat zone of the flame front. The measurements of laminar flame speeds are carried out in a high-pressure and high-temperature constant-volume vessel over a wide range of equivalence ratios for methane, ethanol, and isooctane/air mixtures. To validate the experimental facility and the postprocessing of the flame images, fresh gas velocities and unstretched laminar burning velocities, as well as Markstein lengths relative to burned and unburned gases, are presented and compared with experimental and numerical results of the literature for methane/air flames. New results concerning ethanol/air and isooctane/air flames are presented for various experimental conditions (373 K, equivalence ratios range 0.7–1.5, pressure range 0.1–5 MPa).

  • Measurement of laminar burning velocity and Markstein length relative to fresh gases using a new postprocessing Procedure: Application to laminar spherical flames for methane, ethanol and isooctane/air mixtures
    Combustion and Flame, 2012
    Co-Authors: Emilien Varea, Alexis Vandel, Vincent Modica, B. Renou
    Abstract:

    The purpose of this study is to present a new tool for extracting the laminar burning velocity in the case of spherically outward expanding flames. This new Procedure makes it possible to determine the laminar burning velocity directly based on the flame displacement speed and the global fresh gas velocity near the preheat zone of the flame front. It therefore presents a very interesting alternative to the standard method (commonly used in the literature), which is based on the flame front displacement and the ratio of unburned and burned gas densities. The influence of external flame stretching on the burning velocity can be characterized and the Markstein length relative to the unburned gases (i.e., fresh gases) can be deduced by using this new tool. Contrary to the standard Procedure, the unstretched laminar burning velocity is determined directly without using the fuel mixture properties. The temporal evolution of the flame front is visualized by high-speed laser tomography and the algorithm, based on a tomographic image correlation method, makes it possible to accurately measure the fresh gas velocity near the preheat zone of the flame front. The measurements of laminar flame speeds are carried out in a high-pressure and high-temperature constant-volume vessel over a wide range of equivalence ratios for methane, ethanol, and isooctane/air mixtures. To validate the experimental facility and the postprocessing of the flame images, fresh gas velocities and unstretched laminar burning velocities, as well as Markstein lengths relative to burned and unburned gases, are presented and compared with experimental and numerical results of the literature for methane/air flames. New results concerning ethanol/air and isooctane/air flames are presented for various experimental conditions (373. K, equivalence ratios range 0.7-1.5, pressure range 0.1-5. MPa). © 2011 The Combustion Institute.

Fernando Barbosa - One of the best experts on this subject based on the ideXlab platform.

  • mercury speciation in seafood samples by lc icp ms with a rapid ultrasound assisted extraction Procedure Application to the determination of mercury in brazilian seafood samples
    Food Chemistry, 2011
    Co-Authors: Bruno Lemos Batista, Jairo Lisboa Rodrigues, Samuel S De Souza, Vanessa Cristina De Oliveira Souza, Fernando Barbosa
    Abstract:

    Abstract This paper describes a simple method for mercury speciation in seafood samples by LC–ICP-MS with a fast sample preparation Procedure. Prior to analysis, mercury species were extracted from food samples with a solution containing mercaptoethanol, l -cysteine and HCl and sonication for 15 min. Separation of mercury species was accomplished in less than 5 min on a C8 reverse phase column with a mobile phase containing 0.05%-v/v mercaptoethanol, 0.4% m/v l -cysteine and 0.06 mol L −1 ammonium acetate. The method detection limits were found to be 0.25, 0.20 and 0.1 ng g −1 for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Certified Reference Materials (DOLT-3 and DORM-3) from the National Research Council Canada (NRCC). With the proposed method there is a considerable reduction of the time of sample preparation. Finally, the method was applied for the speciation of mercury in seafood samples purchased from the Brazilian market.