Refine
Year of publication
Document Type
- Article (11)
- Part of Periodical (1)
- Preprint (1)
Is part of the Bibliography
- yes (13)
Keywords
- Aimé Bonpland (1)
- Air showers (1)
- Alexander Humboldt Moses (1)
- Antisana (1)
- Avé-Lallemant (1)
- Baron von Eschwege (1)
- Bauforschung (1)
- Bergakademie Freiberg (1)
- British Museum (1)
- Chalchiuhtlicue (1)
Introducing the CTA concept
(2013)
The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project.
In the last decade, there has been an increasing interest in compensating thermally induced errors to improve the manufacturing accuracy of modular tool systems. These modular tool systems are interfaces between spindle and workpiece and consist of several complicatedly formed parts. Their thermal behavior is dominated by nonlinearities, delay and hysteresis effects even in tools with simpler geometry and it is difficult to describe it theoretically. Due to the dominant nonlinear nature of this behavior the so far used linear regression between the temperatures and the displacements is insufficient. Therefore, in this study we test the hypothesis whether we can reliably predict such thermal displacements via nonlinear temperature-displacement regression functions. These functions are estimated firstly from learning measurements using the alternating conditional expectation (ACE) algorithm and then tested on independent data sets. First, we analyze data that were generated by a finite element spindle model. We find that our approach is a powerful tool to describe the relation between temperatures and displacements for simulated data. Next, we analyze the temperature-displacement relationship in a silent real experimental setup, where the tool system is thermally forced. Again, the ACE-algorithm is powerful to estimate the deformation with high precision. The corresponding errors obtained by using the nonlinear regression approach are 10-fold lower in comparison to multiple linear regression analysis. Finally, we investigate the thermal behavior of a modular tool system in a working milling machine and get again promising results. The thermally inducedaccuracy using this nonlinear regression analysis. Therefore, this approach seems to be very useful for the development of new modular tool systems. errors can be estimated with 1-2 micrometer
In the last decade, there has been an increasing interest in compensating thermally induced errors to improve the manufacturing accuracy of modular tool systems. These modular tool systems are interfaces between spindle and workpiece and consist of several complicatedly formed parts. Their thermal behavior is dominated by nonlinearities, delay and hysteresis effects even in tools with simpler geometry and it is difficult to describe it theoretically. Due to the dominant nonlinear nature of this behavior the so far used linear regression between the temperatures and the displacements is insufficient. Therefore, in this study we test the hypothesis whether we can reliably predict such thermal displacements via nonlinear temperature-displacement regression functions. These functions are estimated firstly from learning measurements using the alternating conditional expectation (ACE) algorithm and then tested on independent data sets. First, we analyze data that were generated by a finite element spindle model. We find that our approach is a powerful tool to describe the relation between temperatures and displacements for simulated data. Next, we analyze the temperature-displacement relationship in a silent real experimental setup, where the tool system is thermally forced. Again, the ACE-algorithm is powerful to estimate the deformation with high precision. The corresponding errors obtained by using the nonlinear regression approach are 10-fold lower in comparison to multiple linear regression analysis. Finally, we investigate the thermal behavior of a modular tool system in a working milling machine and get again promising results. The thermally induced errors can be estimated with 1-2${mu m}$ accuracy using this nonlinear regression analysis. Therefore, this approach seems to be very useful for the development of new modular tool systems.
A case of primary progressive ahasia : a 14year follow-up study with neuropathological findings
(1998)
Rapid recovery of aphasia and deep dyslexia after extensive left-hemisphere damage in childhood
(1994)
-Ingo Schwarz, Vera M. Kutzinski: A Letter from Alexander von Humboldt to Joseph Albert Wright – Archival Traces
-Foni Le Brun-Ricalens, Leonardo López Luján, Claude Wey: Alexander von Humboldts „Aztekische Priesterin“ alias die Chalchiuhtlicue aus der Sammlung Guillermo Dupaix. Historiografischer Essay einer Translokation von Mexico-Stadt nach London
-Eberhard Knobloch: Leibniz und Alexander von Humboldt
-Irene Prüfer Leske: Wie stand es nun wirklich um Bonpland? Kritische Überlegungen zu Frank Holls Untersuchung zu Bonpland, seiner Beziehung zu Alexander von Humboldt und der Darstellung der letzten Tage von Bonpland durch Avé-Lallemant
-Leonhard Salzer, Anna Nöbauer: (Auf) Humboldts Spuren Eine bauforscherische Untersuchung der „Casa Humboldt“ am Antisana in Ecuador
-Renate Sternagel: Alexander von Humboldt, Therese von Bacheracht, und die „verhängnissvolle Prosa des Lebens“
-Ulrich Stottmeister: Der Mineraloge August Schmidt und die Entdeckung der Ural-Diamanten 1829 Teil I: Schmidts Weg in den Ural und die Diamanten-Vorhersage
-Kurt-R. Biermann (1919 – 2002) und Ingo Schwarz: Der polyglotte Alexander von Humboldt (mit einer Vorbemerkung von Jürgen Trabant)
-Tobias Kraft: Filología nómada. Repensar la obra de Alexander von Humboldt con la obra de Ottmar Ette (y viceversa)