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Prague, Czech Republic

Czech Technical University in Prague (České vysoké učení technické v Praze – ČVUT in Czech, is one of the largest universities in the Czech Republic, and is one of the oldest institutes of technology in Central Europe. It is also the oldest non-military technical university in Europe.In the academic year 2012/2013 8 faculties and 1 university institute of Czech Technical University offered 105 degree programs and 419 fields of study, which enrolled more than 24,500 students. Wikipedia.

Jakubek J.,Czech Technical University
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

The semiconductor pixel detector Timepix (256×256 pixels with pitch of 55 μm) is a successor of the Medipix2 device. Each Timepix pixel can be independently operated in one of three possible modes: (1) counting of the detected particles; (2) measurement of the particle energy; and (3) measurement of the time of interaction. The energy measurement in the second mode is performed via the determination of the time-over-threshold (TOT). The energy measurement with the Timepix detector in TOT mode requires knowledge of the energy calibration of each pixel of the matrix. Such calibration is very nonlinear in the low energy range and can be described by a surrogate function depending on four parameters. The determination of all these parameters can be performed by measurement and evaluation of the response of each pixel in at least four calibration points. The procedure is extremely demanding: it requires the analysis of at least 250 thousand spectra and the performance of 330 thousand least-squares fits. In this article, it is demonstrated that even better result can be achieved with only two or three calibration points halving the number of least-squares fits needed. The method is based on precise analysis of the shape of spectral peaks. The article also discusses the performance of energy calibrated device for spectrometry of heavy charged particles. © 2010 Elsevier B.V. All rights reserved. Source

Kybic J.,Czech Technical University
IEEE Transactions on Image Processing | Year: 2010

We address the problem of estimating the uncertainty of pixel based image registration algorithms, given just the two images to be registered, for cases when no ground truth data is available. Our novel method uses bootstrap resampling. It is very general, applicable to almost any registration method based on minimizing a pixel-based similarity criterion; we demonstrate it using the SSD, SAD, correlation, and mutual information criteria. We show experimentally that the bootstrap method provides better estimates of the registration accuracy than the state-of-the-art Cramér-Rao bound method. Additionally, we evaluate also a fast registration accuracy estimation (FRAE) method which is based on quadratic sensitivity analysis ideas and has a negligible computational overhead. FRAE mostly works better than the Cramér-Rao bound method but is outperformed by the bootstrap method. © 2009 IEEE. Source

Tlusty D.,Czech Technical University
Nuclear Physics A | Year: 2013

In this article, we report on the STAR results of open charm hadron production at mid-rapidity in p + p and Au + Au collisions at √sNN=200 GeV and p + p collisions at s=500 GeV. The measurements cover transverse momentum range from 0.6 to 6 GeV/c for p + p 200 GeV collisions, from 1 to 6 GeV/c for p + p 500 GeV collisions and from 0 to 6 GeV/c for Au + Au 200 GeV collisions. D0 nuclear modification factor and elliptic flow in Au + Au collisions at sNN=200 GeV are presented. © 2013 Elsevier B.V. Source

Papuga J.,Czech Technical University
International Journal of Fatigue | Year: 2011

This paper presents a comprehensive overview of the main currently published fatigue prediction models for estimating the multiaxial fatigue limit. The set of analyzed criteria comprises 17 different methods, which are tested on a series of 407 experiments. The methods are briefly described and the overall tendencies of their prediction capabilities are commented on, including some properties common to certain groups of criteria. The set of experiments refers to the publicly available FatLim database. The computation results were achieved using the PragTic freeware fatigue solver. The Papuga PCr method is the best solution at present. Some possible ways of further improving the methods are proposed here. © 2010 Elsevier Ltd. All rights reserved. Source

Werner T.,Czech Technical University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2010

We present a number of contributions to the LP relaxation approach to weighted constraint satisfaction (= Gibbs energy minimization). We link this approach to many works from constraint programming, which relation has so far been ignored in machine vision and learning. While the approach has been mostly considered only for binary constraints, we generalize it to n-ary constraints in a simple and natural way. This includes a simple algorithm to minimize the LP-based upper bound, n-ary max-sum diffusionhowever, we consider using other bound-optimizing algorithms as well. The diffusion iteration is tractable for a certain class of high-arity constraints represented as a black box, which is analogical to propagators for global constraints CSP. Diffusion exactly solves permuted n-ary supermodular problems. A hierarchy of gradually tighter LP relaxations is obtained simply by adding various zero constraints and coupling them in various ways to existing constraints. Zero constraints can be added incrementally, which leads to a cutting-plane algorithm. The separation problem is formulated as finding an unsatisfiable subproblem of a CSP. © 2010 IEEE. Source

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