5 research outputs found
How to Peel a Million: Validating and Expanding Bitcoin Clusters
One of the defining features of Bitcoin and the thousands of cryptocurrencies
that have been derived from it is a globally visible transaction ledger. While
Bitcoin uses pseudonyms as a way to hide the identity of its participants, a
long line of research has demonstrated that Bitcoin is not anonymous. This has
been perhaps best exemplified by the development of clustering heuristics,
which have in turn given rise to the ability to track the flow of bitcoins as
they are sent from one entity to another.
In this paper, we design a new heuristic that is designed to track a certain
type of flow, called a peel chain, that represents many transactions performed
by the same entity; in doing this, we implicitly cluster these transactions and
their associated pseudonyms together. We then use this heuristic to both
validate and expand the results of existing clustering heuristics. We also
develop a machine learning-based validation method and, using a ground-truth
dataset, evaluate all our approaches and compare them with the state of the
art. Ultimately, our goal is to not only enable more powerful tracking
techniques but also call attention to the limits of anonymity in these systems
Microdosimetric GEANT4 and FLUKA Monte Carlo simulations and measurements of heavy ion irradiation of silicon and tissue
We describe microdosimetric measurements and simulations with Geant4 and FLUKA Monte Carlo codes in silicon and tissue. Analyses of deposited energy in sensitive volumes of some micrometers were carried out after exposure to heavy ion radiatio
Investigations on Photon Energy Response of RadFET Using Monte Carlo Simulations
International audienceWe describe investigations of RadFET energy response simulated with Geant4 and FLUKA2005 Monte Carlo codes. An analysis of energy deposition is carried out for photon irradiation with energies between 35 keV and 2 MeV. The absorbed dose in the silicon dioxide layer (few hundred nanometers) is compared for both transport codes
MATSIM: Development of a Voxel Model of the MATROSHKA Astronaut Dosimetric Phantom
The AIT Austrian Institute of Technology coordinates
the project MATSIM (MATROSHKA Simulation) in
collaboration with the Vienna University of Technology and the
German Aerospace Center, to perform FLUKA Monte Carlo
simulations of the MATROSHKA numerical phantom irradiated
under reference radiation field conditions as well as for the
radiation environment at the International Space Station (ISS).
MATSIM is carried out as co-investigation of the ESA ELIPS
projects SORD and RADIS (commonly known asMATROSHKA),
an international collaboration of more than 18 research institutes
and space agencies from all over the world, under the science and
project lead of the German Aerospace Center. During MATSIM
a computer tomography scan of the MATROSHKA phantom has
been converted into a high resolution 3-dimensional voxel model.
The energy imparted and absorbed dose distribution inside the
model is determined for various radiation fields. The major goal
of the MATSIM project is the validation of the numerical model
under reference radiation conditions and further investigations
under the radiation environment at ISS. In this report we compare
depth dose distributions inside the phantom measured with thermoluminescence
detectors (TLDs) and an ionization chamber with
FLUKA Monte Carlo particle transport simulations due to Co-60
photon exposure. Further reference irradiations with neutrons,
protons and heavy ions are planned. The fully validated numerical
model MATSIM will provide a perfect tool to assess the radiation
exposure to humans during current and future space missions to
ISS, Moon, Mars and beyond