@TechReport{	  it:2003-032,
  author	= {Daniel Noreland},
  title		= {Impedance Boundary Conditions for Acoustic Waves in a Duct
		  with a Step Discontinuity},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Scientific Computing},
  year		= {2003},
  number	= {2003-032},
  month		= may,
  abstract	= {This paper treats the use of numerically computed
		  impedance boundary conditions for acoustic simulations.
		  Such boundary conditions may be used to combine different
		  methods on different parts of the computational domain.
		  Impedance boundary conditions may be computed for each
		  subproblem independently of each other. In order to develop
		  insight into this approach, wave propagation in a
		  rectangular waveguide with a step discontinuity is
		  studied.}
}