A Morphing Algorithm for Generating Near Optimal Grids: Applications in Computational Medicine|
School of Computing Technical Report, S.G. Parker, D.M. Weinstein, C.R. Johnson. No. UUCS-94-014, University of Utah, 1994.
Computational Engineering and Science at the University of Utah|
C.R. Johnson, P. Alfeld. In IEEE Computational Science and Engineering, pp. 7--9. 1994.
An Automatic Adaptive Refinement and Derefinement Method|
F. Yu, C.R. Johnson. In Proceedings of the 14th IMACS World Congress, pp. 1555--1557. 1994.
High Performance Computing in Medicine: Direct and Inverse Problems in Cardiology|
C.R. Johnson, R.S. MacLeod. In IEEE Engineering in Medicine and Biology Society 15th Annual International Conference, pp. 582--583. 1993.
A 3D Cellular Automata Model of the Heart|
P.B. Gharpure, C.R. Johnson. In IEEE Engineering in Medicine and Biology Society 15th Annual International Conference, IEEE Press, pp. 752--753. 1993.
Computer Simulations Reveal Complexity of Electrical Activity in the Human Thorax|
C.R. Johnson, R.S. MacLeod, M.A. Matheson. In Computers in Physics, Vol. 6, pp. 230--237. May/June, 1992.
An Adaptive Theta Method for the Solution of Stiff and Non-stiff Differential Equations|
M. Berzins, R.M. Furzeland. In Applied Numerical Mathematics, Vol. 9, pp. 1--19. 1992.
Berzins, M. and R.M. Furzeland, An adaptive theta method for the solution of stiff and nonstiff differential
Effects of Anistropy and Inhomogeneity on Electrocardiographic Fields: A Finite Element Study|
C.R. Johnson, R.S. MacLeod, A. Dutson. In Engineering in Medicine and Biology Society 14th Annual International Conference, IEEE Press, pp. 2009--2010. 1992.
A Computer Model for the Study of Electrical Current Flow in the Human Thorax|
C.R. Johnson, R.S. MacLeod, P.R. Ershler. In Computers in Biology and Medicine, Vol. 22, No. 5, Elsevier BV, pp. 305--323. 1992.
Electrocardiography has played an important role in the detection and characterization of heart function, both in normal and abnormal states. In this paper we present an inhomogeneous, anisotropic computer model of the human thorax for use in electrocardiography with emphasis on the calculation of transthoracic potential and current distributions. Knowledge of the current pathways in the thorax has many applications in electrocardiography and has direct utility in studies pertaining to cardiac defibrillation, forward and inverse problems, impedance tomography, and electrode placement in electrocardiography.
Keywords: scalar field methods, vector field methods, tensor field methods, cardiac heart, scientific visualization
Computational Studies of Forward and Inverse Problems in Electrocardiology|
C.R. Johnson, R.S. MacLeod. In Biomedical Modeling and Simulation, Edited by J. Eisenfeld and D.S. Levine and M. Witten, Elsevier Science Publishers, Elsevier, Amsterdam pp. 283--290. 1992.
Nonuniform Spatial Mesh Adaption Using a Posteriori Error Estimate: Applications to Forward and Inverse Problems|
C.R. Johnson, R.S. MacLeod. In Adaptive Methods for Partial Differential Equations, Vol. 14, Edited by J.E. Flaherty and M.S. Shephard, Elsevier, pp. 311--326. 1992.
Balancing Space and Time Errors for Spectral Methods used with the Method of Lines for Parabolic equations|
M. Berzins. 1991.
Computer Models for Calculating Transthoracic Current Flow|
C.R. Johnson, R.S. MacLeod. In IEEE Engineering in Medicine and Biology Society 13th Annual International Conference, IEEE Press, pp. 768--769. 1991.
Construction of an Inhomogeneous Model of the Human Torso for Use in Computational Electrocardiography|
R.S. MacLeod, C.R. Johnson, P.R. Ershler. In IEEE Engineering in Medicine and Biology Society 13th Annual International Conference, IEEE Press, pp. 688--689. 1991.
Chebyshev Polynomial Software for Elliptic-Parabolic Systems of P.D.E.s|
M. Berzins, P.M. Dew. In A.C.M. Transactions on Mathematical Software, Vol. 17, No. 2, pp. 178--206. June, 1991.
PDECHEB is a FORTRAN 77 software package that semidiscretizes a wide range of time dependent partial differential equations in one space variable. The software implements a family of spatial discretization formulas, based on piecewise Chebyshev polynomial expansions with C0 continuity. The package has been designed to be used in conjunction with a general integrator for initial value problems to provide a powerful software tool for the solution of parabolic-elliptic PDEs with coupled differential algebraic equations. Examples are provided to illustrate the use of the package with the DASSL d.a.e, integrator of Petzold .
Electrical Activation of the Heart: Computational Studies of the Forward and Inverse Problems in Electrocardiography|
C.R. Johnson, A.E. Pollard. In Computer Assisted Analysis and Modeling, MIT Press, pp. 583--628. 1990.
Developing Software for Time-Dependent Problems Using the Method of Lines and Differential Algebraic Integrators|
M. Berzins, P.M. Dew, R.M. Furzeland. In Applied Numerical Mathematics, Vol. 5, pp. 375--397. 1989.
A C1 Interpolant for Codes Based on Backward Differentiation Formulae|
M. Berzins. In Applied Numerical Mathematics, Vol. 2, pp. 109--118. 1986.
This note is concerned with the provision of an interpolant for o.d.e. initial value codes based upon backward differentiation formulae (b.d.f.) in which both the solution and its first time derivative are continuous over the range of integration--a C1 interpolant. The construction and implementation of the interpolant is described and the continuity achieved in practice is illustrated by two examples.