In this paper, we present a regularization method in the nonstationary inverse problem for diffuse optical tomography (DOT). The regularization is based on a choosing time evolution process such that in a stationary state it has a covariance function which corresponds to a process with similar smoothness properties as the first-order smoothness Tikhonov regularization. The proposed method is co...

In this paper we present Netalyzr, a network measurement and debugging service that evaluates the functionality provided by people’s Internet connectivity. The design aims to prove both comprehensive in terms of the properties we measure and easy to employ and understand for users with little technical background. We structure Netalyzr as a signed Java applet (which users access via their Web b...

National Geographic Institute of Spain (IGN-E) wanted to integrate its main information sources for building a common vocabulary reference and thus to manage the huge amount of information it held. The main problem of this integration is the great heterogeneity of data sources. The Ontology Engineering Group (OEG) is working with IGN-E to attain this objective in two phases: first, by creating ...

The SIFEM project targets the development of an infrastructure in order to semantically link open source tools and libraries with existing data as well as new knowledge towards the multi-scale finite element modelling of the innerear. The SIFEM system is designed based on an open architecture schema that consists of a set of tools and subsystems in order to develop robust multi-scale models. Th...

We have applied positron annihilation spectroscopy to study in-grown vacancy defects in bulk aluminium nitride (AlN) crystals grown by physical vapor transport. We interpret the lowest lifetime value of about 155ps, measured at low temperatures, to represent the annihilations from the free state of the positron in the crystal lattice. The increased lifetime at high temperatures is an indication...

This article studies the response of a half-disk exposed to an external uniform static electric field. A semianalytical method is presented for computing the potential for a geometry consisting of two conjoined half-disks with different permittivities. The method is based on analytical series expansions with coefficients obtained as a numerical solution of a matrix equation. We consider the pol...

In this article, we present a system intended to help students understand and debug concurrent Java programs. The system instruments Java classes to produce execution traces. These traces can then be used to construct a dynamic dependence graph showing the interactions between the different operations performed in the program. These interactions are used as the basis for an interactive visualis...

In many complex computational processes one may want to store a sample of the process’ history for later use by placing checkpoints. In this paper we consider the problem of maintaining, in an online fashion, a collection of k checkpoints as an approximately uniformly spaced sample in the history of a continuous-time process. We present deterministic algorithms tailored for small values of k an...