The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Theodore J. Plappert - One of the best experts on this subject based on the ideXlab platform.

  • Effective aortic regurgitant orifice area: description of a method based on the Conservation of Mass.
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is

  • effective aortic regurgitant orifice area description of a method based on the Conservation of Mass
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is <4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheterderived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of aortic regurgitation as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.

Sharon C. Reimold - One of the best experts on this subject based on the ideXlab platform.

  • Effective aortic regurgitant orifice area: description of a method based on the Conservation of Mass.
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is

  • effective aortic regurgitant orifice area description of a method based on the Conservation of Mass
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is <4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheterderived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of aortic regurgitation as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.

P. Kachroo - One of the best experts on this subject based on the ideXlab platform.

  • Sliding mode control of hyperbolic PDE system with parametric variations
    2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011
    Co-Authors: S.a. Wadoo, P. Kachroo, Neveen Shlayan
    Abstract:

    In this paper design of nonlinear sliding mode feedback controller for a model representing crowd dynamics is presented. The model is presented as hyperbolic partial differential equation based on the laws of Conservation of Mass. The feedback control is designed in presence of uncertainties due to parametric variations. The controller is designed using sliding mode method. The controllers designed are shown to be robust to parametric variation.

  • ITSC - Time-Optimal Control for One Dimensional Evacuation System
    2007 IEEE Intelligent Transportation Systems Conference, 2007
    Co-Authors: S.a. Wadoo, P. Kachroo
    Abstract:

    This paper presents design of a time-optimal controller for a model representing evacuation dynamics in one dimension. The model presented here is based on the law of Conservation of Mass. The model is the classical one equation model for a traffic flow based on Conservation of Mass with a prescribed relationship between density and velocity. The equations of motion are described by nonlinear partial differential equations. We address the optimal control problem for the space discretized dynamics thus making use of nonlinear ordinary differential equations. The objective is to synthesize a nonlinear open loop controller that evacuates people in minimum time. Necessary conditions for time-optimal solution are derived. Pontryagin's minimum principle is used to arrive at a bang-bang form for optimal control.

  • Time-Optimal Control for One Dimensional Evacuation System
    2007 IEEE Intelligent Transportation Systems Conference, 2007
    Co-Authors: S.a. Wadoo, P. Kachroo
    Abstract:

    This paper presents design of a time-optimal controller for a model representing evacuation dynamics in one dimension. The model presented here is based on the law of Conservation of Mass. The model is the classical one equation model for a traffic flow based on Conservation of Mass with a prescribed relationship between density and velocity. The equations of motion are described by nonlinear partial differential equations. We address the optimal control problem for the space discretized dynamics thus making use of nonlinear ordinary differential equations. The objective is to synthesize a nonlinear open loop controller that evacuates people in minimum time. Necessary conditions for time-optimal solution are derived. Pontryagin's minimum principle is used to arrive at a bang-bang form for optimal control.

  • ITSC - Feedback Control Design and Stability Analysis of One Dimensional Evacuation System
    2006 IEEE Intelligent Transportation Systems Conference, 2006
    Co-Authors: S.a. Wadoo, P. Kachroo
    Abstract:

    This paper presents design of nonlinear feedback controllers for two different models representing evacuation dynamics in two dimensions. The models presented here are based on the laws of Conservation of Mass and momentum. The first model is the classical one equation model for a traffic flow based on Conservation of Mass with a prescribed relationship between density and velocity. The other model is a two equation model in which the velocity is independent of the density. This model is based on Conservation of Mass and momentum. The equations of motion in both cases are described by nonlinear partial differential equations. We address the feedback control problem for both models. The objective is to synthesize a nonlinear distributed feedback controller that guarantees stability of a closed loop system. The problem of control and stability is formulated directly in the framework of partial differential equations. Sufficient conditions for Lyapunov stability for distributed control are derived

  • Feedback control design and stability analysis of two dimensional evacuation system
    2006 IEEE Intelligent Transportation Systems Conference, 2006
    Co-Authors: S.a. Wadoo, P. Kachroo
    Abstract:

    This paper presents design of nonlinear feedback controllers for two different models representing evacuation dynamics in two dimensions. The models presented here are based on the laws of Conservation of Mass and momentum. The first model is the classical one equation model for a traffic flow based on Conservation of Mass with a prescribed relationship between density and velocity. The other model is a two equation model in which the velocity is independent of the density. This model is based on Conservation of Mass and momentum. The equations of motion in both cases are described by nonlinear partial differential equations. We address the feedback control problem for both models. The objective is to synthesize a nonlinear distributed feedback controller that guarantees stability of a closed loop system. The problem of control and stability is formulated directly in the framework of partial differential equations. Sufficient conditions for Lyapunov stability for distributed control are derived

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

  • Effective aortic regurgitant orifice area: description of a method based on the Conservation of Mass.
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is

  • effective aortic regurgitant orifice area description of a method based on the Conservation of Mass
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is <4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheterderived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of aortic regurgitation as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.

John A. Bittl - One of the best experts on this subject based on the ideXlab platform.

  • Effective aortic regurgitant orifice area: description of a method based on the Conservation of Mass.
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is

  • effective aortic regurgitant orifice area description of a method based on the Conservation of Mass
    Journal of the American College of Cardiology, 1991
    Co-Authors: Sharon C. Reimold, Peter Ganz, John A. Bittl, James D. Thomas, David H. Thoreau, Theodore J. Plappert
    Abstract:

    The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of Conservation of Mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is <4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheterderived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of aortic regurgitation as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.