The Experts below are selected from a list of 18903 Experts worldwide ranked by ideXlab platform

Claudia Becker - One of the best experts on this subject based on the ideXlab platform.

  • RDELA—a Delaunay-triangulation-based, location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators’ efficiency.

  • rdela a delaunay triangulation based location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators' efficiency.

Steffen Liebscher - One of the best experts on this subject based on the ideXlab platform.

  • RDELA—a Delaunay-triangulation-based, location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators’ efficiency.

  • rdela a delaunay triangulation based location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators' efficiency.

Thomas Kirschstein - One of the best experts on this subject based on the ideXlab platform.

  • RDELA—a Delaunay-triangulation-based, location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators’ efficiency.

  • rdela a delaunay triangulation based location and covariance estimator with high breakdown point
    Statistics and Computing, 2013
    Co-Authors: Steffen Liebscher, Thomas Kirschstein, Claudia Becker
    Abstract:

    We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of Elliptical Shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimators' efficiency.

Alexandrina Untaroiu - One of the best experts on this subject based on the ideXlab platform.

  • Elliptical Shape Hole-Pattern Seals Performance Evaluation Using Design of Experiments Technique
    Journal of Fluids Engineering-transactions of The Asme, 2018
    Co-Authors: Hanxiang Jin, Alexandrina Untaroiu
    Abstract:

    Hole-pattern annular gas seals have two distinct flow regions: an annular jet-flow region between the rotor and stator, and cylindrical indentions in the stator that serve as cavities where flow recirculation occurs. As the working fluid enters the cavities and recirculates, its kinetic energy is reduced, resulting in a reduction of leakage flow rate through the seal. The geometry of the cylindrical cavities has a significant effect on the overall performance of the seal. In this study, the effects of Elliptical Shape hole pattern geometry on the leakage and dynamic response performance of an industry-relevant hole-pattern seal design are investigated using a combination of computational fluid dynamics (CFD), hybrid bulk flow-CFD analysis, and design of experiments (DOEs) technique. The design space was defined by varying the values of five geometrical characteristics: the major and minor radius of hole, the angle between the major axis and the axis of the seal, the spacing between holes along the seal axis, and hole spacing in the circumferential direction. This detailed analysis allowed for a greater understanding of the interaction effects from varying all of these design parameters together as opposed to studying them one variable at a time. Response maps generated from the calculated results demonstrate the effects of each design parameter on seal leakage as well as the co-dependence between the design parameters. The data from this analysis were also used to generate linear regression models that demonstrate how these parameters affect the leakage rate and the dynamic coefficients, including the effective damping.

  • Elliptical Shape Hole-Pattern Seals Performance Evaluation Using Design of Experiments Technique
    Volume 1A Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verificati, 2016
    Co-Authors: Hanxiang Jin, Alexandrina Untaroiu
    Abstract:

    Hole-pattern annular gas seals have been proven to be very effective in reducing leakage flow between high and low pressure sections in turbomachinery. This type of seal has two distinct flow regions: an annular jet-flow region between the rotor and stator, and cylindrical indentions in the stator that serve as cavities where flow recirculation occurs. As the working fluid enters the cavities and recirculates, its kinetic energy is reduced, resulting in a reduction of leakage flow rate through the seal. The geometry of the cylindrical cavities has a significant effect on the overall performance of a hole-pattern annular gas seal. Previous studies have been primarily focused on cylindrical cavities that are perpendicular to the axis of the seal and have indicated that the performance may be improved by varying the depths, spacing, and diameters of the cavities. However, to date the effects of Elliptical cylinder cavities has yet to be investigated. In this study, the effects of Elliptical Shape hole pattern geometry on the leakage and dynamic response performance of an industry-relevant hole-pattern seal design are investigated using a combination of computational fluid dynamics (CFD), hybrid bulk flow/CFD analysis, and design of experiments techniques. A CFD model of the baseline hole-pattern seal was first developed and validated against experimental data. A design of experiments (DOE) study was then performed to investigate the effect that various Elliptical Shape cavities had on the leakage rate through the seal. CFD simulations were run for multiple geometry configurations of the cylindrical cavities to evaluate the seal performance at each of the design points. The design space was defined by varying the values of five geometrical characteristics: the major and minor radius of hole, the angle between the major axis and the axis of the seal, the spacing between holes along the seal axis, and hole spacing in the circumferential direction. Quadratic polynomial fitting was then used to analyze the sensitivity of different design variables with respect to the different outputs. This detailed analysis allowed for a greater understanding of the interaction effects from varying all of these design parameters together as opposed to studying them one variable at a time. Response maps generated from the calculated results demonstrate the effects of each design parameter on seal leakage as well as the relationships between the design parameters. The data from this analysis was also used to generate linear regression models that demonstrate how these parameters affect the leakage of the seal. The results of this study could aid in improving future designs of hole-pattern annular gas seals.

Andres Nietoleal - One of the best experts on this subject based on the ideXlab platform.