On the Influence of a Five-Hole-Probe on the Vibration Characteristics of a Low Pressure Turbine Rotor while Performing Aerodynamic Measurements

For many reasons it is essential to know and assess the flow field and its characteristics up- and downstream of a turbine stage. For these purpose measurements are conducted in test rigs such as the STTF-AAAI (subsonic test turbine facility for aerodynamic, acoustic, and aeroelastic investigations) at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. A low pressure turbine is operated in engine relevant operating conditions. The turbine is experienced high mechanical loads and is excited to vibrate (forced response). In the rotor design process forced response predictions and structural assessments are performed. However, it is not common to include instrumentation (e.g. total pressure and temperature rakes, five-hole-probes, fast response aerodynamic pressure probes) in these forced response predictions. But, these measurement devices are essential and therefore this paper investigates the influence of such an instrumentation onto the vibrational behaviour of a low pressure turbine rotor of the STTF-AAAI. Several vibration measurements at distinct circumferential and radial positions of the five-hole-probe in the flow channel are conducted. These measurement results are compared to measurements performed without a five-hole-probe in the flow channel. A clear influence of the five-hole-probe on the vibration level is shown

Expressing Confidence in Models and in Model Transformation Elements.

The expression and management of uncertainty, both in the information and in the operations that manipulate it, is a critical issue in those systems that work with physical environments. Measurement uncertainty can be due to several factors, such as unreliable data sources, tolerance in the measurements, or the inability to determine if a certain event has actually happened or not. In particular, this contribution focuses on the expression of one kind of uncertainty, namely the confidence on the model elements, i.e., the degree of belief that we have on their occurrence, and on how such an uncertainty can be managed and propagated through model transformations, whose rules can also be subject to uncertainty

Evaluating the usability of a visual feature modeling notation

International audienceFeature modeling is a popular Software Product Line Engineering (SPLE) technique used to describe variability in a product family. A usable feature modeling tool environment should enable SPLE practitioners to produce good quality models, in particular, models that effectively communicate modeled information. FAMILIAR is a text-based environment for manipulating and composing Feature Models (FMs). In this paper we present extensions we made to FAMILIAR to enhance its usability. The extensions include a visualization of FMs, or more precisely , a feature diagram rendering mechanism that supports the use of a combination of text and graphics to describe FMs, their configurations, and the results of FM analyses. We also present the results of a preliminary evaluation of the environment's usability. The evaluation involves comparing the use of the extended environment with the previous text-based console-driven version. The preliminary experiment provides some evidence that use of the new environment results in increased cognitive effectiveness of novice users and improved quality of new FMs

Towards the systematic construction of domain-specific transformation languages

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-09195-2-13Proceedings of 10th European Conference, ECMFA 2014, Held as Part of STAF 2014, York, UK, July 21-25, 2014General-purpose transformation languages, like ATL or QVT, are the basis for model manipulation in Model-Driven Engineering (MDE). However, as MDE moves to more complex scenarios, there is the need for specialized transformation languages for activities like model merging, migration or aspect weaving, or for specific domains of wide use like UML. Such domain-specific transformation languages (DSTLs) encapsulate transformation knowledge within a language, enabling the reuse of recurrent solutions to transformation problems. Nowadays, many DSTLs are built in an ad-hoc manner, which requires a high development cost to achieve a full-featured implementation. Alternatively, they are realised by an embedding into general-purpose transformation or programming languages like ATL or Java. In this paper, we propose a framework for the systematic creation of DSTLs. First, we look into the characteristics of domain-specific transformation tools, deriving a categorization which is the basis of our framework. Then, we propose a domain-specific language to describe DSTLs, from which we derive a ready-to-run workbench which includes the abstract syntax, concrete syntax and translational semantics of the DSTL.This work has been funded by the Spanish Ministry of Economy and Competitivity with project “Go Lite” (TIN2011-24139

Modelling and Verification of Timed Robotic Controllers

Designing robotic systems can be very challenging, yet controllers are often specified using informal notations with development driven primarily by simulations and physical experiments, without relation to abstract models of requirements. The ability to perform formal analysis and replicate results across different robotic platforms is hindered by the lack of well-defined formal notations. In this paper we present a timed state-machine based formal notation for robotics that is informed by current practice. We motivate our work with an example from swarm robotics and define a compositional CSP-based discrete timed semantics suitable for refinement. Our results support verification and, importantly, enable rigorous connection with sound simulations and deployments.</p

Meta-modeling model-based engineering tools (Dagstuhl Seminar 13182)

Model-based engineering (MBE) is a software development approach in which abstraction via modeling is used as the primary mechanism for managing the complexity of software-based systems. An effective approach to software development must be supported by effective technologies (i.e., languages, methods, processes, tools). The wide range of development tasks that effective MBE approaches must support leads to two possible tooling scenarios. In the first scenario a federated collection of tools is used to support system development. Each tool in the collection provides specialized services. Tool interoperability and consistency of information across the tools are major concerns in this scenario. These concerns are typically addressed using transformations and exposed tool interfaces. Defining and evolving the transformations and interfaces requires detailed low-level knowledge of the tools and thus leads to complex tooling environments that are difficult to configure, learn, use, and evolve. In the second scenario, a single tool is used to support the complete modeling lifecycle. This avoids the inter-tool transformation and consistency problems, but the resulting multi-featured tool is a monolithic entity that is costly to develop and evolve. Furthermore, the large number of non-trivial features can make learning and using such tools difficult. Successful uptake of MDE in industry requires supporting tools to be, at least, useful and usable. From a tool developer's perspective, there is also a need to significantly reduce the cost and effort required to develop and evolve complex MBE tools. This seminar brings together experts in the areas of MBE, meta-modeling, tool development, and human-computer interactions to map out a research agenda that lays a foundation for the development of effective MBE tools. Such a foundation will need to support not only interoperability of tools or tool features, but also the implementation of high quality MBE tools. The long-term objective is to foster a research community that will work on a foundation that can be expressed in the form of standard tool (meta-)models that capture and leverage high quality reusable MBE tool development experience