Technische Universität Darmstadt

About: Technische Universität Darmstadt is a education organization based out in Darmstadt, Germany. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 17316 authors who have published 40619 publications receiving 937916 citations. The organization is also known as: Darmstadt University of Technology & University of Darmstadt.

Mining Minimal Non-redundant Association Rules Using Frequent Closed Itemsets

Abstract: The problem of the relevance and the usefulness of extracted association rules is of primary importance because, in the majority of cases, real-life databases lead to several thousands association rules with high confidence and among which are many redundancies. Using the closure of the Galois connection, we define two new bases for association rules which union is a generating set for all valid association rules with support and confidence. These bases are characterized using frequent closed itemsets and their generators; they consist of the nonredundant exact and approximate association rules having minimal antecedents and maximal consequents, i.e. the most relevant association rules. Algorithms for extracting these bases are presented and results of experiments carried out on real-life databases show that the proposed bases are useful, and that their generation is not time consuming.

Carbohydrates as Organic Raw Materials

Abstract: In view of the impending transition of chemical industry from depleting fossil raw materials to renewable feedstocks — the end of cheap oil is predicted around 2040 — this account gives an overview on chemically and enzymatically transforming carbohydrates, by far the major part of the annually regrowing biomass, into products with versatile industrial application profiles and the potential to eventually replace those presently derived from petrochemical sources. The article contains sections titled: 1. Introduction 2. Availability of Carbohydrates 3. Current Nonfood Industrial Products from Sugars 3.1. Ethanol 3.2. Furfural 3.3 d-Sorbitol 3.4 Lactic Acid and Polylactic Acid (PLA) 3.5. Sugar-Based Surfactants 3.5.1. ‘Sorbitan’ Esters 3.5.2. N-Methyl-N-acyl-glucamides (NMCA) 3.5.3. Alkylpolyglucosides (APG) 3.5.4. Sucrose Fatty Acid Monoesters 3.6. Pharmaceuticals and Vitamins 4. Toward Further Sugar-based Chemicals: Potential Development Lines 4.1. Furan Compounds 4.1.1. 5-Hydroxymethylfurfural (HMF) 4.1.2. 2,5-Dimethylfuran (DMF) 4.1.3. Furans with a Tetrahydroxybutyl Side Chain 4.2. Dihydropyrones 4.3. Sugar-Derived Unsaturated Nitrogen Heterocycles 4.3.1. Pyrroles 4.3.2. Pyrazoles 4.3.3. Imidazoles 4.3.4. 3-Pyridinols 4.4. Toward Sugar-Based Aromatic Chemicals 4.5. Microbial Conversion of Six-Carbon-Sugars into Simple Carboxylic Acids and Alcohols 4.5.1. Carboxylic Acids 4.5.2. Potential Sugar-Based Alcohol Commodities by Microbial Conversions 4.6. Chemical Conversion of Sugars into Carboxylic Acids 4.7. Biopolymers from Polymerizable Sugar Derivatives 4.7.1. Synthetic Biopolyesters 4.7.2. Microbial Polyesters 4.7.3. Polyamides 5. Outlook 6. References

Comprehensive simulation of quadrotor UAVs using ROS and gazebo

Abstract: Quadrotor UAVs have successfully been used both in research and for commercial applications in recent years and there has been significant progress in the design of robust control software and hardware. Nevertheless, testing of prototype UAV systems still means risk of damage due to failures. Motivated by this, a system for the comprehensive simulation of quadrotor UAVs is presented in this paper. Unlike existing solutions, the presented system is integrated with ROS and the Gazebo simulator. This comprehensive approach allows simultaneous simulation of diverse aspects such as flight dynamics, onboard sensors like IMUs, external imaging sensors and complex environments. The dynamics model of the quadrotor has been parameterized using wind tunnel tests and validated by a comparison of simulated and real flight data. The applicability for simulation of complex UAV systems is demonstrated using LIDAR-based and visual SLAM approaches available as open source software.

First results from the CERN axion solar telescope.

Abstract: Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by the Primakoff process. In a laboratory magnetic field (``axion helioscope''), they would be transformed into x-rays with energies of a few keV. Using a decommissioned Large Hadron Collider test magnet, the CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from the analysis of these data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling ${g}_{a\ensuremath{\gamma}}l1.16\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ at 95% C.L. for ${m}_{a}\ensuremath{\lesssim}0.02\text{ }\mathrm{eV}$. This limit, assumption-free, is comparable to the limit from stellar energy-loss arguments and considerably more restrictive than any previous experiment over a broad range of axion masses.

Sterically demanding trialkylphosphines for palladium-catalyzed cross coupling reactions—alternatives to PtBu3

Abstract: The strong electron-donation and the steric bulk of trialkylphosphines renders them as very useful ligands for palladium-catalyzed cross coupling reactions. This critical review reports on the synthesis of two families of trialkylphosphines (diadamantylalkylphosphines, fluorenyldialkylphosphines) and the properties of the respective palladium complexes in various cross coupling reactions, which evolved as alternatives to the classical Pd/PtBu3 system. In contrast to the latter phosphine the new classes of ligands are characterized by a highly flexible ligand design, which allows the fine tuning of catalytic properties to the specific needs of certain substrates and also enables the attachment of additional tags to impart certain useful properties onto the respective phosphines (179 references).