Open Source in aeronautics and space research

At the German Aerospace Center (DLR) many different Open Source products are used, especially in the field of software development. From source code management up to third party libraries open source software become more and more used in the process of development. At the same time, new programs as well as existing ones are getting open source or developers from the DLR spending time to contribute to existing open source projects. In this talk, we will give an overview about the different Open Source software tools that are used in the aeronautics and space research. We also will show how more and more software out of the research area are released as Open Source and why Apache Licence is playing a key role. Finally we will give an example about how the open source development of an Apache module leads to an cooperated project of DLR and NASA

Tool Integration and Data Formats for Distributed Airplane Predesign

The internal architecture of the Java plugin components, developed for the TIVA, EVITA, CATS, UCAV-2010 and similar projects

Gesellschaftlicher Aufbruch, reale Utopien und die Arbeit am Sozialen

People around the world recollect socially responsible and desirable values, new forms of living and coexistence as well as eco-social economic activities. This volume is dedicated to these real utopias –positive ideas aiming at a better future and practical approaches combining notions of a more livable society with concrete practical implementations.Weltweit besinnen sich Menschen auf gesellschaftlich Verantwortbares und Wünschenswertes, auf neue Formen des Lebens und Zusammenlebens und des ökosozialen Wirtschaftens. Dieser Band widmet sich diesen realen Utopien, positiven, in eine bessere Zukunft gerichteten Vorstellungen und praktischen Ansätzen, die Ideen von einer lebenswerteren Gesellschaft mit konkreter Praxis verbinden

Integration Framework for Preliminary Design Toolchains

The goals defined by the ACARE Vision 2020 present a major challenge to aeronautic research. Besides developments in new aerodynamics and structures, advancements in aero engine research will account for a major part of the required reduction in fuel, emissions and noise. To enable a commercial launch of new aircraft and engine concepts, complex and often contradictory demands have to be fulfilled. Strong dependencies between the individual technical disciplines exist so that the optimization in a single discipline may not lead inevitably to a global optimum. Therefore it is necessary to look at the overall system in order to evaluate the potential of new technologies realistically. This article presents a typical design task in aeroengine predesign and a software solution which supports and enables multidisciplinary cooperation on the engineer side. A common data format based on XML, necessary for data exchange, as well as supporting programming libraries for the processing of this data format are introduced. Furthermore it is described, how a parametric representation can be realized for various geometries with the help of XML. A programming library with C and FORTRAN Interfaces supports geometrical computations for these representations. Finally it is demonstrated that the tools used by the different technical disciplines can be connected to a process chain within a framework

Evaluation of Modeling Languages for Preliminary Airplane Design in Multidisciplinary Design Environments

The coupling of physical effects and the rising complexity of modern aircraft necessitate an intense collaboration of disciplinary specialists in preliminary airplane design. Additionally, a growing number of suppliers and outsourced design activities aggravate the design processes even further. Novel multidisciplinary design environments intend to enable specialists to better integrate analysis codes and constitute the consistent technical basis for their cooperation. In this manner different technical aspects can be evaluated quickly, since the data update and analysis capabilities are available throughout the design team. The exchange of information is therefore of crucial importance in multidisciplinary design. Due to the fact that in data exchange the number of interfaces is the critical factor for the flexibility of a design environment, a central information model is a key feature. The central information model reflects among other things the common namespace of the design team and can be seen as the meta-model for all of the deduced analysis models. The architecture of such a novel design environment is strongly linked to principles of model-based architectures and the chosen underlying software engineering techniques influence strongly the efficiency of the resulting design processes. An information model for a design environment as described above consists of two aspects. On the one hand the elements, attributes and their structure need to be defined in a schema definition. On the other hand the explicit content has to be stored in a data set conform to the schema definition. Whereas the data set is mainly used for the exchange of information, the schema definition is utilized for documentation, model validation and model generation. Several possibilities of attributes for a quality information model are named in the literature and are outlined in this research. These attributes or requirements include important aspects like holism, accessibility, transparency and ordering mechanisms. Additionally, several abstraction methods need to be taken into account that are mostly based on principles of object oriented modeling. Information models commonly used in preliminary airplane design include STEP, XML and most recently the Unified Modeling Language (UML). The Standard for the Exchange of Product Data (STEP) is described in ISO 10303. STEP is widely spread in the industry. The meta-models are built up using the object flavored modeling language EXPRESS. Content models are stored either via plain text or XML formats. The Common Parametric Aircraft Configuration Schema (CPACS) is a DLR intern standard. It is used in several multidisciplinary projects that handle the scope of preliminary airplane design and further aspects like climate impact and transport systems. The standard is based on XML and benefits from a growing number of tools that are adapted to it. As UML is concerned, there is not yet a standard for the modeling of preliminary aircraft data, this work provides therefore an outlook on some of the research in this area. Traditionally, the UML is a powerful software modeling language and the only of the introduced language concepts that features a truly integrated model. The different modeling languages and approaches are reviewed in respect to the quality characteristics already mentioned. Their development history is displayed and existing approaches for the application of these techniques to preliminary airplane design in the academic as well as industrial field are shown. An evaluation of the named modeling languages is made with respect to the existing multidisciplinary design environment at the DLR. Future developments for the different modeling languages are outlined and potential crossovers highlighted. It is shown that CPACS can be translated to an UML model. Additionally, a CPACS to STEP translator is introduced outlining the software mechanisms applied and showing a validation example using the geometry data of the VFW-614 ATTAS. This research concludes in an evaluation of several techniques for information modeling taken from computer science to a multidisciplinary engineering design environment for preliminary airplane design. The central information model contained therein forms the basis for distributed modeling and simulation. Its proper parameterization allows therefore a more firm and consolidated assessment of known aircraft designs as well as of some of the potential aircraft technologies of tomorrow

Testing Apache Modules with Python and Ctypes

Writing tests for your Apache module is often a developer's least favourite task, especially if you don't like using the Perl Apache Testing Framework! One of the main reasons for this is that it's difficult to test your C code on-the-fly without a running Apache server. Using ctypes, you can test your modules without a running httpd, just by writing and using simple Python scripts! In this talk we will look at how to compile a specific version of the Apache webserver for testing, and how to use a common Python unit testing framework to write and set up tests. We will also cover examples of writing simple test cases for the Catacomb WebDAV Server module

Open Source Software Framework for Applications in Aeronautics and Space

The DLR developed the open source software framework RCE to support the collaborative and distributed work in the shipyard industry. From a technology side of view a software from the shipbuilding field has many requirements in common with aerospace software projects. Accordingly, RCE has become the basis for further projects within the DLR. Over the last years of usage a subset of frequently used software components could be derived and are provided by the RCE framework. In particular, the workflow engine, allowing the integration of different domain-specific tools from local and remote locations into one overall calculation has become important for various projects. We present RCE and show how its software components are reused in two aerospace applications

Advances in Generalization and Decoupling of Software Parts in a Scientific Simulation Workflow System

Scientific simulation workflows today consist of a pool of simulation models of different domains that are linked together. In the past this was often done with highly specific connections between the simulation models, e. g., batch-scripts or use of commercial integrated systems prescribing certain procedures. This strong coupling led to several problems like the non-reusability of a simulation model in other contexts or other software environments. To address this situation a concept called Chameleon was developed to provide a general decoupled approach between the models. The separation of concerns principle was applied to disconnect the models, their data and a underlying simulation framework as clearly as possible. The Chameleon ideas have been realized on top of the integration frameworks ModelCenter and Remote Component Environment. The feasibility and the advantages of this concept will be pointed out in this paper. After discussing our experiences with drawbacks and merits of the currently used commercial framework and the transition to an open-source framework we give an outlook on future topics, which are relevant for a simulation software integration in scientific collaboration on a daily basis

The Catacomb WebDAV Server

Catacomb is a WebDAV repository module for use with the Apache WebDAV module, mod_dav. Apache mod_dav parses WebDAV and DeltaV protocol requests into operations on a repository providing persistent storage of resources and their properties. The default repository for mod_dav is provided by a separate module, mod_dav_fs, which stores resource bodies as files in the filesystem, and stores properties in a (G)DBM database. Catacomb provides a replacement for mod_dav_fs called mod_dav_repos that stores resources and their properties in a relational database using mod_dbd from the apache project for database abstraction. The primary advantage of this approach is the searching capabilities of the database are used to implement the DASL protocol. Additionally, the database allows straightforward implementation of the versioning capabilities of the DeltaV protocol. We will present the current state of development of the catacomb WebDAV server. We also explain the use of catacomb for storing scientific data in the german aerospace center. Finally there will be an outlook of future WebDAV protocol extensions in catacomb and how they will be realized

Implementierung des Access Control Protocols in den Catacomb WebDAV Server

Im Rahmen dieser Diplomarbeit wurde ein Konzept erstellt, um das im RFC 3744 beschriebene Access Control Protocol in den Catacomb WebDAV Server einzubinden. Es wurde das WebDAV Protokoll vorgestellt und gezeigt wie der Catacomb Server funktioniert. Dann wurde das Access Control Protocol vorgestellt und ein passendes Datenbankmodell erstellt, das das bereit vorhandene erweitert. Auf Grundlage des Software-Designs wurde dann die ACP Erweiterung für Catacomb und die notwendigen Erweiterungen in dem Apache2 Modul mod_dav implementiert. Außerdem wurde ein differenzierteres Speicherverhalten in Catacomb implementiert, sodass angegeben werden kann ab welcher Dateigröße Ressourcen im Dateisystem gespeichert werden sollen anstatt in der Datenbank. Als nächstes wurde das Softwareergebnis mit geeigneten Mitteln getestet. Es wurde neben Einzeltests auch automatisierte Programme wie die Litmus WebDAV Server Test Suit zum Testen der Kompatibilität eingesetzt. Dabei wurde ein Bug im WebDAVExplorer entdeckt und mit den Entwicklern besprochen. Als letztes wurde die Performance des Systems mit einer Auswahl anderer WebDAV Server verglichen und anschließend fand ein ausführlicherer Vergleich der zwei verschiedenen Catacomb Server statt. Dazu wurde der Quellcode der Prestan Performance Test Suit um einige Tests erweitert, um den Anforderungen des DLR gerecht zu werden. Anschließend wurde die Performance mehrerer WebDAV Server gemessen und gegenübergestellt, ebenso wie der Catacomb Server in einer Version mit und einer ohne Access Control Protocol verglichen wurden. Dabei wurde die Frage untersucht, ob und wie sehr die Implementierung des Access Control Protocols die Geschwindigkeit des Servers beeinflusst hat