Towards a modeling language for Systems-Theoretic Process Analysis (STPA) : Proposal for a domain specific language (DSL) for model driven Systems-Theoretic Process Analysis (STPA) based on UML

Dieser Artikel schlägt eine modellbasierte domänen-spezifische Sprache zur Modellierung von Sicherheitsanalyse nach der STAMP/STPA Methode vor. Im Dokument werden die einzelnen Modellierungskonstrukte detailliert beschrieben, sowie deren Zusammenhänge definiert.The article proposes a model-based domain-specific language for the STAMP/STPA safety analysis technique. The document describes the modeling artefacts and their relationships in detail

Thread-local, step-local proof obligations for refinement of state-based concurrent systems

This paper presents a proof technique for proving refinements for general state-based models of concurrent systems that reduces proving forward simulations to thread-local, step-local proof obligations. Instances of this proof technique should be applicable to systems specified with ASM rules, B events, or Z operations. To exemplify the proof technique, we demonstrate it with a simple case study that verifies linearizability of a lock-free implementation of concurrent hash sets by showing that it refines an abstract concurrent system with atomic operations. Our theorem prover KIV translates programs to a set of transition rules and generates proof obligations according to the technique

Shell-Model Study of Shears Bands in Light Pb Nuclei

Spherical shell-model calculations have been performed in the configuration space ( s1/2h9/2i13/2) and (p1/2p3/2f5/2i13/2) for protons and neutrons, respectively, in order to interpret the sequences of strong dipole transitions found in neutron-deficient Pb isotopes. Regular dipole bands are found if several high-j protons and high-j neutron holes are interacting with neutrons in the low-spin (fp) orbitals. The calculated B(M1) values are in the order of several µN2 for the deltaJ=1 transitions, and the crossover E2 transitions are very weak. The mechanism generating the dipole bands is found to be the same as in the tilted axis cranking mean-field description

Verification of forward simulations with thread-local, step-local proof obligations

This paper presents a proof technique for proving refinements for general state-based models of concurrent systems that reduces proving forward simulations to thread-local, step-local proof obligations. The approach has been implemented in our theorem prover KIV, which translates imperative programs to a set of transition rules and generates proof obligations accordingly. Instances of this proof technique should also be applicable to systems specified with ASM rules, B events, or Z operations. To exemplify the proof methodology, we demonstrate it with two case studies. The first verifies linearizability of a lock-free implementation of concurrent hash sets by showing that it refines an abstract concurrent system with atomic operations. The second applies the proof technique to the verification of opacity of Transactional Mutex Locks (TML), a Software Transactional Memory algorithm. Compared to the standard approach of proving a forward simulation directly, both case studies show a significant reduction in proof effort

ifo Konjunkturprognose 2016–2018: Robuste deutsche Konjunktur vor einem Jahr ungewisser internationaler Wirtschaftspolitik

Am 16. Dezember 2016 stellte das ifo Institut seine Prognose für die Jahre 2016, 2017 und 2018 vor. Der robuste Aufschwung, in dem sich die deutsche Wirtschaft seit dem Jahr 2013 befindet, wird sich fortsetzen. In diesem Jahr ist mit einem Zuwachs des realen BIP von 1,9% zu rechnen. 2017 dürfte der Anstieg auf 1,5% zurückgehen, was jedoch nur auf eine im Vergleich zum Vorjahr geringere Anzahl von Arbeitstagen zurückzuführen ist. Im Jahr 2018 wird das reale BIP vor­aussichtlich um 1,7% expandieren. Allerdings sind die Risiken, mit denen diese Prognose behaftet ist, außerordentlich hoch. Mit dem Brexit-Referendum, der US-Präsidentenwahl und der gescheiterten Verfassungsreform in Italien hat sich die globale politische Landschaft stark verändert, was weitreichende und in hohem Maße ungewisse Konsequenzen für die Weltwirtschaft und Deutschland in den kommenden Jahren haben könnte. Wird die US-amerikanische Finanzpolitik – wie vom neugewählten Präsidenten angekündigt – deutlich expansiver, dürfte dies der Konjunktur in den USA und dem Rest der Welt signifikante positive Impulse bescheren. Ein hohes und fortwährendes Maß an politischer Unsicherheit sowie zunehmende politische und wirtschaftliche Desintegration würden die wirtschaftlichen Aussichten merklich beeinträchtigen

Abschätzbare und skalierbare Koordinierung mehrfädiger Prozesse

Emerging application scenarios like self-driving cars and the Internet of Things need computing systems that provide high computation performance with low power draw under timeliness constraints. Due to their power and performance requirements, these systems have to utilise highly-parallel hardware architectures. However, it is difficult to analyse the resource demand (i.e., energy and latency) of individual operations on conventional parallel systems. This resource-unawareness often prohibits highly-parallel systems from application in resource-critical environments, in particular, where response-time or energy-related constraints have to be satisfied. This thesis introduces the concept of estimability of a computing system, and system-level software in particular, that makes resource-awareness in parallel computing systems feasible. In particular, this concept enables a resource-demand analysis with high accuracy despite little effort. The motivation behind estimability are various frequently-applied design patterns in parallel systems that cause an accumulation of seemingly minor disturbances, such that the aggregation of all interferences is performance-critical. In consequence, an accurate resource-demand analysis of such a system is infeasible because all possible combinations of disturbances have to be considered—in practice, resource-demand analyses are therefore tedious and inaccurate. This thesis introduces several approaches to avoid these problematic patterns, in order to prevent the accumulation of disturbances. Systems have to be designed specifically to be estimable, that is, to allow for a resource-demand analysis that is accurate despite requiring little effort. This idea leads to a system architecture based on partitions, where each partition can be individually analysed with relatively little effort. To collectively satisfy performance requirements, however, these partitions have to cooperate, by means of communication. Unfortunately, communication is traditionally one of the patterns that cause the accumulation of disturbances. This thesis therefore introduces multiple means for coordination that limit the potential accumulation of interferences. In consequence, patterns of accumulating disturbances can be broken up, and an analysis can be much more accurate (as there is only little variation in resource demand) with significantly reduced effort (as interferences between partitions are avoided, despite communication). This thesis introduces approaches that improve the estimability of computing systems, with focus on methods for coordination between cooperating partitions. Several approaches operate by construction. There, the system is specifically designed in a way that improves estimability. In particular, this thesis introduces a variety of novel coordination mechanisms where potential interferences are bounded, and disturbances cannot accumulate arbitrarily. Further approaches are based on adaptation. They apply machine-learning techniques to modify low-level components at run-time, in order to provide an estimable behaviour to semantically higher levels. The practicability of adaptation-based approaches is demonstrated on the basis of a real-time communication system for the Internet of Things. Finally, this thesis discusses the resource demand of suitable machine-learning techniques for system-level adaptation, considering both hardware and software. Since these techniques guide adaptation mechanisms, their resource demand has to be estimable as well, to enable whole-system estimability