Institute for Information Technology OFFIS

Oldenburg, Germany

Institute for Information Technology OFFIS

Oldenburg, Germany

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Frascella A.,ENEA | Swiderski J.,Polish Institute of Power Engineering | Proserpio G.,RSE SpA | Rikos E.,Center for Renewable Energy Sources CRES | And 5 more authors.
Proceedings - 2015 International Symposium on Smart Electric Distribution Systems and Technologies, EDST 2015 | Year: 2015

A huge set of Smart Grid related standards already exist and is continuously being updated in various technical working groups in various parts of the world. Ongoing EU-funded ELECTRA Integrated Research Programme (IRP) on Smart Grids [1] aims to re-use the existing standards within its in progress activities considering to be in compliance with the standardization groups like CEN/CENELEC/ETSI, NIST and others. Moving towards the implementation of the functional architecture, it is important to be aware of the information to be exchanged and how communication protocols can be used in support of Smart Grid information exchange. Therefore, a reference method needs to be developed for assessing and classifying the ICT interoperability standards and specifications. The existing Common Assessment Method for Standards and Specifications (CAMSS) is thought to be a tool for Public Administration choices of standards, especially for e-government and e-procurement in EU. Despite CAMSS defines an evaluation schema for standards and specifications via an Excel tool, this paper shows that the CAMSS approach needs to be modified and adapted for the goals of ELECTRA IRP. Moreover, the elaborated tool would not only be useful for ELECTRA purposes but it would be used in a broader Smart Grid (SG) perspective as well and also, with some slight adaptations, more in general, for all complex contexts involving a high number of standards (e.g. the Smart City context). © 2015 IEEE.


Gezgin T.,Institute for Information Technology OFFIS | Etzien C.,Institute for Information Technology OFFIS | Henkler S.,Institute for Information Technology OFFIS | Rettberg A.,Carl von Ossietzky University
Proceedings - 2012 15th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing Workshops, ISORCW 2012 | Year: 2012

The scope of this paper is collaborative, distributed safety critical systems which build up a larger scale system of systems (SoS). Systems participating in an SoS follow both global as well as individual goals, which may be contradicting. Both the global and local goals of the overall SoS may change over time. Hence, self-adaptive ness, i.e., reconfiguration of the SoS as a reaction on changes within its context is a major characteristic of this systems. The aim of this paper is to describe first steps towards a modeling formalism for SoS in a safety critical context. The challenge is to address on the one hand the required flexibility to adapt the system during run-time and on the other hand to guarantee that the system reacts still in a safe manner. To address these challenges, we propose an approach which guarantees that the system still reacts in a safe manner while adaption to uncertainty including context changes. This adaption has to be assumed as unsafe during design time. The key for having success is to define the interaction between the systems as well as its goals as basic elements of the design. Based on our former work, we propose a well-defined modeling approach for the interaction based on components as basic structural elements, the contract paradigm for the design of the interaction, and graph transformations, which addresses the adaptivity of system of systems. The component model is additionally explicitly enriched by goals, which supports so called evaluation functions to determine the level of target achievement. © 2012 IEEE.


Stierand I.,Carl von Ossietzky University | Malipatlolla S.,Institute for Information Technology OFFIS | Froschle S.,Institute for Information Technology OFFIS | Stuhring A.,Carl von Ossietzky University | Henkler S.,Institute for Information Technology OFFIS
Proceedings - IEEE 25th International Symposium on Software Reliability Engineering Workshops, ISSREW 2014 | Year: 2014

Conventionally, the process of design space exploration (DSE) in embedded system design considers performance, energy and cost as important objectives for optimization. However, in many domains such as in modern day cars the security aspect is becoming more and more significant. On the other hand, the inclusion of security aspect adds a new dimension to the existing complexity of large design spaces, thus an automated support for this is highly desired. The goal of this work is to integrate the security constraint in an automated DSE process to obtain an architecture which is both cost-optimized and secure. In specific, for a given system, our approach defines a formal notion of security, which along with other parameters is fed as an input to the DSE process to obtain an architecture satisfying the defined security and real-time requirements. An evaluation of the proposed approach is also performed using an example automotive embedded system. © 2014 IEEE.


Gezgin T.,Institute for Information Technology OFFIS | Henkler S.,Institute for Information Technology OFFIS | Rettberg A.,Carl von Ossietzky University | Stierand I.,Carl von Ossietzky University
Brazilian Symposium on Computing System Engineering, SBESC | Year: 2012

Nowadays, most embedded safety critical systems have to work in a timely manner in order to deliver desired services. In such timed systems not only ordering of events but timing properties are relevant for correctness and performance. In order to be safe and reliable, it is important to have rigorous analysis techniques of timing-dependent (state) behavior. Classical scheduling approaches consider only the system behavior stateless. Especially for safety critical systems this is not sufficient as the state space gives important information of the system which has to be considered by analysis approaches. Our approach for scheduling analysis combines analytical and model checking methods. We consider not only critical instances but the full state space for analysis, where all inter-leavings and task dependencies are preserved. For this, the state space of the entire system architecture is constructed with the aid of input event streams for tasks, and the known behavior of the scheduler of each resource. Based on the state space response times can be determined, and safety properties can be verified by means of reachability checks. As this approach alone is not scalable we present abstraction techniques based on determining output event streams for each resource. For this we exploit well known analytical methods for scheduling analysis. These methods typically abstracts from all inter-leavings leading to very pessimistic results. In this work we present an abstraction technique that is relevant if multiple activations of one task can occur. This technique lies in the middle of both approaches mentioned above. © 2012 IEEE.


Gezgin T.,Institute for Information Technology OFFIS | Henkler S.,Institute for Information Technology OFFIS | Stierand I.,Carl von Ossietzky University | Rettberg A.,Carl von Ossietzky University
Proceedings - 2014 12th IEEE International Conference on Industrial Informatics, INDIN 2014 | Year: 2014

The analysis of real-time properties is crucial in safety critical areas. Systems have to work in a timely manner to offer correct services. The analysis of timing properties is particularly difficult for distributed systems when complex interferences between individual tasks can occur. Considering only critical instances, as analytic approaches do, may deliver pessimistic results leading to higher production costs. In previous works we introduced a state-based approach to validate task-and end-to-end deadlines for distributed systems. To improve scalability and reduce the analysis time, the approach computes the state spaces of the individual resources in a compositional fashion. For this, abstraction and composition operations were defined to remove those parts of the inputs of resources which have no influence on the response times of the allocated tasks. In this work, a new abstraction technique is introduced for scenarios where event bursts occur. Further, we extend our approach for systems with cyclic dependencies among the resources. We evaluate our approach on a set of example scenarios and compare the results with the state-of-the-art tool Uppaal. © 2014 IEEE.


Gezgin T.,Institute for Information Technology OFFIS | Henkler S.,Institute for Information Technology OFFIS | Stierand I.,Carl von Ossietzky University | Rettberg A.,Carl von Ossietzky University
RTCSA 2014 - 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications | Year: 2014

The analysis of real-time properties is crucial in safety critical areas, and is particularly difficult for distributed systems as complex interferences between tasks of different priorities can occur. In previous works we have introduced a state-based analysis approach to validate end-to-end deadlines for distributed systems, where the state spaces of all resources, such as processors and buses, are computed in a compositional fashion. For this, abstraction and composition operations were defined to adequately handle task and resource dependencies. During the design process of a system changes occur typically on both the specification and implementation level, such that already performed analyses of the system have to be repeated. In this work, we define a methodology to adequately handle such changes and to determine the minimal part of the affected architecture. For this, we define an appropriate refinement relation between state spaces of the resources. We use contracts to further reduce the re-validation effort. This check takes place at a higher design level, where only the specification is considered. © 2014 IEEE.


Gezgin T.,Institute for Information Technology OFFIS | Stierand I.,Carl von Ossietzky University | Henkler S.,Institute for Information Technology OFFIS | Rettberg A.,Carl von Ossietzky University
Design Automation for Embedded Systems | Year: 2014

Our approach for scheduling analysis combines analytical and model checking methods. We consider the full state space of a system, where all interleavings and task dependencies are preserved. The state space is build in a compositional manner enabling a more scalable technique. For this, we introduce operations on the state spaces of resources, allowing the abstraction of irrelevant parts and the composition of state spaces. Based on the state space of each resource response times are determined, and timing and safety properties can be verified by means of reachability checks. The approach is demonstrated based on an example scenario.The amount of system functions realized by software drastically increased in recent years. Software tasks of safety-critical systems like those in the automotive domain have to work in a timely manner. In such systems not only ordering of events but also timing properties like end-to-end deadlines are relevant for correctness and performance. Unfortunately, due to various inter-dependencies between software tasks the analysis of such properties becomes very complex. The state-of-the-art analysis approach considers only stateless system behaviors and relies on critical instances leading to very pessimistic results. Considering task inter-dependencies would result in more accurate results, though it negatively affects the scalability of the analysis. © 2013, Springer Science+Business Media New York.


Etzien C.,Institute for Information Technology OFFIS | Gezgin T.,Institute for Information Technology OFFIS | Froschle S.,Institute for Information Technology OFFIS | Henkler S.,Institute for Information Technology OFFIS | Rettberg A.,Carl von Ossietzky University
16th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing, ISORC 2013 | Year: 2014

In this work we address evolving systems, which are basically collaborative and distributed systems building up a larger scale system of system (SoS). These systems are able to adapt the current architecture to some changes in the environment. Constituent systems of a SoS, which represent the basic elements of our modeling approach, operate with different degrees of freedom and as a result the self-adaptation and cooperation between a set of constituent systems is driven by local needs. Based on our former work [11], we propose a well-defined modelling approach for SoS capturing both static and dynamic aspects. The aim is to address on the one hand the required flexibility to adapt the systems during run-time, and on the other hand to guarantee that the SoS reacts still in a safe manner. For this, we will use the contract paradigm for both the specification of legal configurations of the SoS, and to specify the dynamicity model, describing how the SoS architecture can change during run-time. Further, we depict how to adapt a system level analysis technique in order to check the dynamicity model against the invariants of the SoS. With this, we are able to determine, whether the SoS can reach some critical configurations. This enables us to modify the dynamicity model in an adequate manner. © 2013 IEEE.


Zimmermann S.,Institute for Information Technology OFFIS | Eichhorn V.,University of Oldenburg | Fatikow S.,University of Oldenburg
IEEE International Conference on Intelligent Robots and Systems | Year: 2012

This paper presents a nanorobotic approach facilitating the transfer and characterization of individual graphene flakes that are grown by different fabrication techniques. The approach makes use of a nanorobotic atomic force microscope system that is integrated into a high resolution scanning electron microscope and focused ion beam device. This combination is used to perform both, the nanorobotic transfer and the mechanical characterization of the graphene flake allowing to systematically analyze different sample areas and to optimize the fabrication processes. Furthermore, the nanorobotic system enables the reliable pick-and-place handling and processing of graphene flakes to realize more comprehensive analysis steps or even the prototyping of graphene-based devices. © 2012 IEEE.

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