FEM Reconstruction#

In this subsection, the parameters used for lethe-rpt-l2-projection-3d and lethe-rpt-fem-reconstruction-3d applications are defined. Here are the default values:

subsection fem reconstruction
  set mesh type                           = dealii
  set mesh filename                       = none
  set z subdivisions                      = 1
  set mesh refinement                     = 0
  set l2 projection before reconstruction = false
  set experimental counts file            = none
  set export positions file               = none
  set search extrapolation limit          = 0.005
  set cost function type                  = relative
  set dof handler file                    = none
  set nodal counts file                   = none
  set search type                         = local
  set search cell proximity level         = 1
  set verbose clock                       = false
end

For both lethe-rpt-l2-projection-3d and lethe-rpt-fem-reconstruction-3d applications, we have to define the mesh:

mesh type: Type of mesh used. Choosing the dealii option will generate a subdivided_cylinder grid, for that reason the number of subdivision in the z direction must be specified with the z subdivisions parameter. For the gmsh option, only meshes for a cylindrical geometry with tetrahedral elements are accepted at the moment. Furthermore, the z-axis should be the axis of symmetry of the cylinder.
Options: dealii or gmsh
mesh filename: Filename of the imported mesh. Specify only if gmsh was the selected option for the mesh type.
Options: Any .msh file
z subdivisions: Number of initial subdivisions along the z-axis. Specify only if dealii was the selected option for the mesh type.
Options: Any positive integer
mesh refinement: Number of global mesh refinements. Specify only if dealii was the selected option for the mesh type.
Options: Any positive integer

For the lethe-rpt-fem-reconstruction-3d application only, we have to define the following parameters:

l2 projection before reconstruction: Enable to run the lethe-rpt-l2-projection-3d application before the reconstruction.
Options : true or false
experimental counts file: Filename of the file containing the experimental photon counts.
Options: Any .txt file
export positions file: Name of the file in which the calculated positions are exported.
Options: Any .csv or .dat filename
cost function type: Type of cost function used to find the position.
Options:relative or absolute
dof handler file: File containing the saved DoF handler.
Options: Any .dof file
nodal counts file: List of files containing the nodal counts from each detector.
Options: Any .counts file
search extrapolation limit: Tolerance when extrapolating from a cell in the reference space to find a particle’s position. The default value is set to \(0.005\). However, for a subdivided cylinder geometry from deal.II, the default tolerance is set to \(1.15̀\) times the cell_height.
Options: Any positive double
search type: Type of search algorithm used to find particle positions. The local option refers to a search algorithm where the next particle position is searched in a scope around the previously found position’s cell. The size of that scope is defined by the search cell proximity level parameter. And the global option refers to the algorithm in which we go through every cell of the grid to find every particle position.
Options: local or global
search cell proximity level: Level of proximity of the search scope to find the next particle position. A search cell proximity level = 1 includes in the search scope the previously found position’s cell and all its adjacent cells. Specify only if local was the selected option for the search type.
Options: Any positive integer
verbose clock: Enable to show total wallclock time elapsed since start.
Options: true or false