Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Context (language use) & Large Hadron Collider. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Microscopic structure of water at elevated pressures and temperatures

Abstract: We report on the microscopic structure of water at sub- and supercritical conditions studied using X-ray Raman spectroscopy, ab initio molecular dynamics simulations, and density functional theory. Systematic changes in the X-ray Raman spectra with increasing pressure and temperature are observed. Throughout the studied thermodynamic range, the experimental spectra can be interpreted with a structural model obtained from the molecular dynamics simulations. A spatial statistical analysis using Ripley’s K-function shows that this model is homogeneous on the nanometer length scale. According to the simulations, distortions of the hydrogen-bond network increase dramatically when temperature and pressure increase to the supercritical regime. In particular, the average number of hydrogen bonds per molecule decreases to ≈0.6 at 600 °C and p = 134 MPa.

Molecular Architecture Based on Metal Triangles Derived from 2,2‘-Bipyrazine (Bpz) and EnMII (M = Pt, Pd)

Abstract: The molecular triangle [{enPt(bpz-N4,N4‘)}3]6+ (en = ethylenediamine; bpz = 2,2‘-bipyrazine) has been crystallized as a C2-symmetric species (1), as a compound of approximate C3 symmetry, and as a mixture of both forms (1b). The two triangles differ in their topologies, their Pt−Pt distances, and their anion binding properties. While for the C2 form insertion of a single PF6- anion in the central cavity is seen in 1b, the C3 forms of 1a and 1b incorporate either two different anions simultaneously, NO3- and ClO4- (1a), or only a single PF6- (1b). Anion inclusion also occurs in solution as detected by 1H NMR spectroscopy. The molecular triangles 1−1b are the kinetic reaction products of enPtII and bpz. The thermodynamic product is the chelate [enPt(bpz-N1,N1‘)]2+ (2a) that is obtained from 1 upon prolonged heating in water. The all-cis geometry of the bpz ligands in the triangle (C3 form) can be locked by chelation of three enPdII to the N1,N1‘ sites. Hexanuclear [{enPt(N4,N4‘-bpz-N1,N1‘)Pden}3]12+ (3) has...

LearnLib: a framework for extrapolating behavioral models

Abstract: In this paper, we present the LearnLib, a library of tools for automata learning, which is explicitly designed for the systematic experimental analysis of the profile of available learning algorithms and corresponding optimizations. Its modular structure allows users to configure their own tailored learning scenarios, which exploit specific properties of their envisioned applications. As has been shown earlier, exploiting application-specific structural features enables optimizations that may lead to performance gains of several orders of magnitude, a necessary precondition to make automata learning applicable to realistic scenarios.

Light-quark and gluon jet discrimination in pp collisions at √s=7 TeV with the ATLAS detector

Abstract: A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb of proton-proton collision data at collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of 10-20 %. In data, light-quark jets can be tagged with an efficiency of while achieving a gluon-jet mis-tag rate of in a range between and for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6 Monte Carlo simulation, where gluon-jet mis-tag rates of 10 % can be reached for a 50 % selection efficiency of light-quark jets using the same jet properties.

Building timing predictable embedded systems

Abstract: A large class of embedded systems is distinguished from general-purpose computing systems by the need to satisfy strict requirements on timing, often under constraints on available resources. Predictable system design is concerned with the challenge of building systems for which timing requirements can be guaranteed a priori. Perhaps paradoxically, this problem has become more difficult by the introduction of performance-enhancing architectural elements, such as caches, pipelines, and multithreading, which introduce a large degree of uncertainty and make guarantees harder to provide. The intention of this article is to summarize the current state of the art in research concerning how to build predictable yet performant systems. We suggest precise definitions for the concept of “predictability”, and present predictability concerns at different abstraction levels in embedded system design. First, we consider timing predictability of processor instruction sets. Thereafter, we consider how programming languages can be equipped with predictable timing semantics, covering both a language-based approach using the synchronous programming paradigm, as well as an environment that provides timing semantics for a mainstream programming language (in this case C). We present techniques for achieving timing predictability on multicores. Finally, we discuss how to handle predictability at the level of networked embedded systems where randomly occurring errors must be considered.