Controlled resolution reconstruction of one-dimensional permittivity profiles

Electromagnetic scattering inverse problems, microwave imaging, reconstruction of dielectric media, remote sensing, tomography

A Comparison of Radiation Dose Between Standard and 3D Angiography in Congenital Heart Disease

Background: The use of three-dimensional rotational angiography (3D-RA) to assess patients with congenital heart diseases appears to be a promising technique despite the scarce literature available. Objectives: The objective of this study was to describe our initial experience with 3D-RA and to compare its radiation dose to that of standard two-dimensional angiography (2D-SA). Methods: Between September 2011 and April 2012, 18 patients underwent simultaneous 3D-RA and 2D-SA during diagnostic cardiac catheterization. Radiation dose was assessed using the dose-area-product (DAP). Results: The median patient age and weight were 12.5 years and 47.5 Kg, respectively. The median DAP of each 3D-RA acquisition was 1093µGy.m2 and 190µGy.m2 for each 2D-SA acquisition (p<0.01). In patients weighing more than 45Kg (n=7), this difference was attenuated but still significant (1525 µGy.m2 vs.413µGy.m2, p=0.01). No difference was found between one 3D-RA and three 2D-SA (1525µGy.m2 vs.1238 µGy.m2, p = 0.575) in this population. This difference was significantly higher in patients weighing less than 45Kg (n=9) (713µGy.m2 vs.81µGy.m2, P = 0.008), even when comparing one 3D-RA with three 2D-SA (242µGy.m2, respectively, p<0.008). 3D-RA was extremely useful for the assessment of conduits of univentricular hearts, tortuous branches of the pulmonary artery, and aorta relative to 2D-SA acquisitions. Conclusions: The radiation dose of 3D-RA used in our institution was higher than those previously reported in the literature and this difference was more evident in children. This type of assessment is of paramount importance when starting to perform 3D-RA.

stochastic method for automated matching of horizons across a fault in 3D seismic data

Seismic analysis, horizon matching, fault tracking, marked point process,stochastic annealing

3-D surface reconstruction using spatial frequency-based approaches under influence of perspective distortion

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2008

Extraction of topological structures in 2D and 3D vector fields

feature extraction, feature tracking, vector field visualization

Extraction of vortex structures in 3D flow fields

Magdeburg, Univ., Fak. für Informatik, Diss., 2009

Context-aware 3D model generation for biomedical applications

Magdeburg, Univ., Fak. für Informatik, Diss., 2014

3D-Druck in der Anwendung : 3. Mitteldeutsches Forum 3D-Druck in der Anwendung, Hochschule Merseburg, 18. Mai 2016

[s.c.]

3D-Druck in der Anwendung : 2. Mitteldeutsches Forum 3D-Druck in der Anwendung, HTWK Leipzig, 27. Mai 2015

[s.c.]

Perception-guided evaluation of 3D medical visualizations

Magdeburg, Univ., Fak. für Informatik, Diss., 2015

3D-Echtzeitrendering mit Ventuz

Ziel der vorliegenden Bachelorarbeit ist es zu erläutern, wie 3D-Echtzeitrendering funktioniert und wie dies mit der Software Ventuz Designer Version 4 von der Firma Ventuz Technology AG durchgeführt wird. Sie ermöglicht dem Anwender, ohne Programmierkenntnis, auf die Funktionen der Grafikkarte über DirectX zuzugreifen. Es wird Grundwissen zum Thema computer-gestützte Bildgenerierung vermittelt, um ein besseres Verständnis für die dahinterliegenden Prozesse und Verfahren zu entwickeln.

Accuracy vs. simplicity: a complex trade-off

Inductive learning aims at finding general rules that hold true in a database. Targeted learning seeks rules for the predictions of the value of a variable based on the values of others, as in the case of linear or non-parametric regression analysis. Non-targeted learning finds regularities without a specific prediction goal. We model the product of non-targeted learning as rules that state that a certain phenomenon never happens, or that certain conditions necessitate another. For all types of rules, there is a trade-off between the rule's accuracy and its simplicity. Thus rule selection can be viewed as a choice problem, among pairs of degree of accuracy and degree of complexity. However, one cannot in general tell what is the feasible set in the accuracy-complexity space. Formally, we show that finding out whether a point belongs to this set is computationally hard. In particular, in the context of linear regression, finding a small set of variables that obtain a certain value of R2 is computationally hard. Computational complexity may explain why a person is not always aware of rules that, if asked, she would find valid. This, in turn, may explain why one can change other people's minds (opinions, beliefs) without providing new information.