Time filter

Source Type

Linz, Austria

Feger R.,Johannes Kepler University | Wagner C.,Danube Integrated Circuit Engineering DICE | Schuster S.,Vatron Gmbh | Scheiblhofer S.,Johannes Kepler University | Stelzer A.,Johannes Kepler University
IEEE Transactions on Microwave Theory and Techniques

In this paper, a method to increase the achievable angle accuracy of a linear digital beamforming array by introducing a reflector element acting as mirror for the electromagnetic wave is presented. The mirror element leads to an increase of the effective array aperture, as well as a quasi-doubling of the number of elements. The major difference compared to a real increase of the number of array elements is that the information from the mirror elements cannot directly be separated from the signals coming from the real antenna elements. Therefore, an alternative approach to classical beamforming algorithms becomes necessary to take advantage of the additional information. In this work, the method of least squares is used to develop an efficiently implementable algorithm. The performance improvement predicted by the Cramér-Rao lower bound is confirmed by measurements conducted with an eight-channel frequency-modulated continuous-wave radar prototype operating at 79 GHz. The beamforming performance improvement observed in the measurements reached up to 16 dB, which is in good agreement with the predicted level. © 2011 IEEE. Source

Schuster S.,Vatron Gmbh
European Signal Processing Conference

Robust estimators that provide accurate parameter estimates even under the condition that classical assumptions like outlier-free additive Gaussian measurement noise do not hold exactly are of great practical importance in signal processing and measurement science in general. Lots of methods for deriving robust estimators exist. In this paper, we derive novel algorithms for robust estimation by modeling the outliers as a sparse additive vector of unknown deterministic or random parameters. By exploiting the separability of the estimation problem and applying recently developed sparse estimation techniques, algorithms that remove the effect of the outlying observations can be developed. Monte Carlo simulations show that the performance of the developed algorithms is practically equal to the best possible performance given by the Crámer-Rao lower bound (CRB) and the mean-squared error (MSE) of the oracle estimator [1], demonstrating the high accuracy. It is shown that the algorithms can be implemented in a computationally efficient manner. Furthermore, some interesting connections to the popular least absolute deviation (LAD) estimator are shown. © EURASIP, 2011. Source

Resch M.,Johannes Kepler University | Scheidl R.,Johannes Kepler University | Gstottenbauer N.,Vatron Gmbh
International Journal of Fluid Power

In the last decade ample of academic and industrial research work in the area of magneto-rheological fluids (MRF's) has been done. Most of the concepts and products developed in this time period (e.g. MRF brakes and clutches) feature a shear mode operation. Hence a majority of the published work is addressing this mode. Nevertheless, the MRF squeeze mode becomes more and more attractive (for damping applications for instance) due to its higher reachable force densities compared to the other modes. In this paper attainable MRF squeeze mode pressures for very small squeeze gaps are experimentally investigated. For squeeze gaps down to few hundredth of a millimetre the mean squeeze pressure reaches nearly 100bar. On the other hand, especially in the squeeze mode, the problem of MRF segregation occurs. In this work three different methods to avoid or to reduce this phenomenon are experimentally tested and discussed. Finally, a simplified analytical relation for the MRF squeeze mode pressure characteristics is presented and compared to experiments. This comparison shows that the analytical model predicts the MRF squeeze pressures with a satisfactory accuracy such that it can be used for dimensioning purposes. © 2010 TuTech. Source

Richter G.,BRAUN Maschinenfabrik GmbH | Ofner R.,Vatron Gmbh | Fauster E.,Vatron Gmbh
SEAISI Quarterly (South East Asia Iron and Steel Institute)

Prior to further processing of semi-finished steel products, it must be ensured that the surfaces of the workpieces are free from scale, cracks and other material flaws. High-pressure grinding has been proven to be an optimal technology for removing such surface defects. With BRAUN's multi-functional HP high-pressure grinding machine, a highly flexible, state-of-the-art facility was developed that allows a fully-automated bright, edge and flaw grinding of billets, blooms, ingots and other products. Automated grinding of partial surface flaws, however, also requires an accurate detection of the defects. Furthermore, adequate editing of the flaw coordinates, subsequent transmission of these data to the control system of the grinding machine, as well as the capability of the grinding machines to accurately approach the flaw are an imperative. In this context, the thermoinductive crack detection system developed by vatron gmbh poses an ideal technology for inspecting the surface of the workpiece. Moreover, BRAUN and vatron gmbh have jointly developed solutions which allow the implementation of integrated, fully-automated systems for flaw detection and flaw grinding, including product identification, Dost-arindino re-inspection and data management. Source

Sedivy C.,Vatron Gmbh | Koubek C.,Vatron Gmbh | Krump R.,Vatron Gmbh
AISTech - Iron and Steel Technology Conference Proceedings

A good understanding of the EAF process combined with the experience of furnace operation of the last decades is the tool for being able to optimize electric arc furnaces. As the process has lots of details, it is inevitable to get as much support from high developed automation systems as possible. Steadily reaching for the process optimum will result in a good furnace performance. The ArCOS electrode control system is one of the most powerful tools supporting producers to reach their targets. Source

Discover hidden collaborations