Der Kreis Oschatz in der friedlichen Revolution 1989/90

Aus der Einleitung S. 7: „...Wenig Beachtung fanden hingegen bislang kleinere Städte, Orte und einzelne Regionen. Was geschah während der revolutionären Ereignisse jenseits der großen Städte? Wurde auch dort die revolutionäre „Wende“ mitgetragen oder gar befördert? Gab es hier, parallel zu den Ereignissen in den Zentren ebenfalls ein revolutionäres Geschehen oder fand hier nur zeitverzögert eine nachholende Anpassung an die durch den revolutionären Prozess gesetzten Vorgaben statt?...

Towards a model-based control for thermoplastic automated fiber placement

Commercial aviation must become climate neutral in the next decades, a key factor are lightweight fuselages that may increase fuel efficiency of an aircraft over its lifetime. New manufacturing processes such as in-situ, thermoplastic Automated Fiber Placement (AFP) enable larger and more complex carbon fiber reinforced components. In order to increase material performance process parameters, have to be controlled precisely. A sensible approach is introduced in this work by implementation of Model-Based Control (MPC), which can accommodate for process specific challenges. A finite element model of the process is designed and integrated in to the control. Subsequently, layup trials validate the improvements and thus show the potential of the control approach

A New Approach for Visualizing UML Class Diagrams

UML diagrams have become increasingly important in the engineering and reengineering processes for software systems. Of particular interest are UML class diagrams whose purpose is to display class hierarchies (generalizations), associations, aggregations, and compositions in one picture. The combination of hierarchical and non-hierarchical relations poses a special challenge to a graph layout tool. Existing layout tools treat hierarchical and non-hierarchical relations either alike or as separate tasks in a two-phase process as in, e.g., cite{See97}. We suggest a new approach for visualizing UML class diagrams leading to a balanced mixture of the following aesthetic criteria: Crossing minimization, bend minimization, uniform direction within each class hierarchy, no nesting of one class hierarchy within another, orthogonal layout, merging of multiple inheritance edges, and good edge labelling. We have realized our approach within the graph drawing library GoVisual. Experiments show the superiority to state-of-the-art and industrial standard layouts

Swimming with ShARCS: Comparison of On-sky Sensitivity With Model Predictions for ShaneAO on the Lick Observatory 3-meter Telescope

The Lick Observatory's Shane 3-meter telescope has been upgraded with a new infrared instrument (ShARCS - Shane Adaptive optics infraRed Camera and Spectrograph) and dual-deformable mirror adaptive optics (AO) system (ShaneAO). We present first-light measurements of imaging sensitivity in the Ks band. We compare measured results to predicted signal-to-noise ratio and magnitude limits from modeling the emissivity and throughput of ShaneAO and ShARCS. The model was validated by comparing its results to the Keck telescope adaptive optics system model and then by estimating the sky background and limiting magnitudes for IRCAL, the previous infra-red detector on the Shane telescope, and comparing to measured, published results. We predict that the ShaneAO system will measure lower sky backgrounds and achieve 20\% higher throughput across the $JHK$ bands despite having more optical surfaces than the current system. It will enable imaging of fainter objects (by 1-2 magnitudes) and will be faster to reach a fiducial signal-to-noise ratio by a factor of 10-13. We highlight the improvements in performance over the previous AO system and its camera, IRCAL.Comment: 13 pages, 5 figures, SPIE Astronomical Telescopes + Instrumentation, Montreal 201

A New Approach for Visualizing UML Class Diagrams

UML diagrams have become increasingly important in the engineering and reengineering processes for software systems. Of particular interest are UML class diagrams whose purpose is to display class hierarchies (generalizations), associations, aggregations, and compositions in one picture. The combination of hierarchical and non-hierarchical relations poses a special challenge to a graph layout tool. Existing layout tools treat hierarchical and non-hierarchical relations either alike or as separate tasks in a two-phase process as in, e.g., cite{See97}. We suggest a new approach for visualizing UML class diagrams leading to a balanced mixture of the following aesthetic criteria: Crossing minimization, bend minimization, uniform direction within each class hierarchy, no nesting of one class hierarchy within another, orthogonal layout, merging of multiple inheritance edges, and good edge labelling. We have realized our approach within the graph drawing library GoVisual. Experiments show the superiority to state-of-the-art and industrial standard layouts

Near net shape thermoplastic preforming with continuously automated cutting and robotic pick and place processes

Today’s automated production lines for carbon fiber reinforced thermoplastic (CFRTP) parts of the aerospace industry are mostly designed for one special part or application. Changing part geometry or material would lead to a complete re-design of the whole process chain. Here comes the flexible and highly automated the DLR process into game: A continuously automated production line “from fabric delivery to the near net shape pre-form – ready for consolidation”. With the paper and presentation, the authors would like to contribute to the industry’s increasing needs of continuously automated but highly flexible process chains for variable high vol-ume CFRTP parts

ShaneAO: wide science spectrum adaptive optics system for the Lick Observatory

A new high-order adaptive optics system is now being commissioned at the Lick Observatory Shane 3-meter telescope in California. This system uses a high return efficiency sodium beacon and a combination of low and high-order deformable mirrors to achieve diffraction-limited imaging over a wide spectrum of infrared science wavelengths covering 0.8 to 2.2 microns. We present the design performance goals and the first on-sky test results. We discuss several innovations that make this system a pathfinder for next generation AO systems. These include a unique woofer-tweeter control that provides full dynamic range correction from tip/tilt to 16 cycles, variable pupil sampling wavefront sensor, new enhanced silver coatings developed at UC Observatories that improve science and LGS throughput, and tight mechanical rigidity that enables a multi-hour diffraction- limited exposure in LGS mode for faint object spectroscopy science.Comment: 11 pages, 10 figures. Presented at SPIE Astronomical Telescopes + Instrumentation conference, paper 9148-7

Towards increased reliability of resistance welded joints for aircraft assembly

This study focuses on the opportunities and challenges of applying the static resistance welding process to a full scale upper shell fuselage demonstrator. An adapted resistance welding setup and process which produces high quality welds over the whole welding surface with a defined weld seam is described. The effects of scaling and the challenges that arise during the welding of the demonstrator are discussed. Approaches to solutions are presented to meet the required reliability of resistance welded joints in application

Inline Quality Control for Thermoplastic Automated Fibre Placement

Aerospace production is relying heavily on quality assurance, especially for lightweight materials such as carbon fiber reinforced plastics (CFRPs). Due to the sequential organization of manufacturing and quality assurance lead times for parts and machine downtime are increased. An example is the highly automated process of thermoset tape laying, where every ply is manually inspected. Customized solutions to integrate quality assurance do exist, however mainly for specific processes and hardware. This leads to costly, isolated and non-transferable systems. At the Center of Lightweight Production Technology in Augsburg, Germany a more versatile and modular concept for inline data acquisition, storage and evaluation is investigated. On the basis of a laser line and camera system a generic inline measurement system for automated fiber placement (AFP) is developed, that is capable to inspect a variety of quality aspects such as positional tolerances and material properties. In a database driven approach the collected data is stored and analyzed. This paper presents the generic inline measurement system, the data storage system and the obtained measurement results for a thermoplastic AFP process. Additionally suggestions for future improvements and possible applications are described