Public defense of the doctoral dissertation will be held on June 9th 2007 at 12 o'clock in auditorium D101 of the Department of Physical Sciences of the University of Helsinki, Finland.
VTT's MultiTrans programme enables modelling of radiation transport in arbitrary 3D geometry. The computational geometry is generated directly from a CAD-model, which makes it possible to use modern design tools. The computational grid is tree-structured and self-adaptive at the material boundaries, where the mesh automatically becomes the finest. With this method, even a complicated geometry can be represented in fine detail without an excessive number of grid points compared to equidistant mesh.
The tree-structure makes it possible to always find a coarser representation for the problem. This enables the use of multigrid method in iterative solution of the transport equation: the problem can be quickly solved on a much coarser grid, and this solution can then be used as an initial guess for the solution on finer grids. Multigrid method accelerates the iterative solution significantly. In addition, the tree structure leads to a smaller number of grid points, which also makes the iterative solution faster. To VTT's knowledge, this is the first application of the tree-multigrid technique to the radiation transport modelling.
The MultiTrans programme has been tested for different radiotherapy, such as boron neutron capture therapy (BNCT) given at VTT's nuclear research reactor, and for reactor physics applications. So far, the MultiTrans programme has been in use only at VTT.
When high accuracy is required, the simplified spherical harmonics approximation of the radiation transport used in MultiTrans has, in some cases, turned out to be problematic. More accurate methods will be studied further.
Press Office | alfa
World's thinnest hologram paves path to new 3-D world
18.05.2017 | RMIT University
Internet of things made simple: One sensor package does work of many
11.05.2017 | Carnegie Mellon University
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.
Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...
22.05.2017 | Event News
17.05.2017 | Event News
16.05.2017 | Event News
22.05.2017 | Materials Sciences
22.05.2017 | Life Sciences
22.05.2017 | Physics and Astronomy