Eu:CROPIS is DLR’s first mission of the Compact Satellite Program. Its primary payload focuses on the research of closed-loop biological, regenerative life support systems, in a simulated gravitational environment of the Moon and Mars over months at a time. This is achieved by rotation of the satellite around its central body axis, using only magnetic torquers as actuators. A secondary payload (“PowerCells”) by the NASA Ames Research Center also utilizes the artificial gravity to conduct growth experiments on genetically modified organisms (GMOs). These payloads and the system design imposed constraints which affected the Assembly Integration and Verification (AIV) program in various ways and created challenges for the relatively small team to find solutions for. The paper to be presented will address the different aspects of the AIV program. This includes the verification of different critical components like the newly developed CFRP pressure vessel containing the primary payload and the Micrometeoroid and Debris Protection Shield, which protects it. Both items went through rigorous testing, including high-velocity impact tests, to ensure their reliability in orbit. Various other aspects concerning the biology had to be taken into account during AIV campaigns: due to the presence of degradable components within the primary payload, a late access capability had to be implemented in order to exchange biology as well as chemistry in cases of launch delays. To allow these operations as close as six months prior to launch, a highly flexible and streamlined acceptance test campaign was developed. A major impact on test planning and logistics was the fact that the secondary payload “PowerCells” contains GMOs, which European and German regulations restrict to be handled exclusively in especially certified laboratories (biosafety level 1 (BSL-1)). Thus, the use of external test facilities for the flight model campaign was not feasible as no European test center is certified to BSL-1. In consequence, the clean room facilities of the DLR Institute of Space Systems had to be certified to BSL-1 and new test infrastructure had to be procured in a short time frame to cover for acceptance testing. The design of the satellite and nature of the attitude control subsystem required limits on the magnetic momentum of the system and every unit it contains. A test flow incorporating the magnetic property measurement of each unit and a final system-level test in an external facility had to be devised, which enabled budgeting and projection of expected measurement results on the system level. Furthermore, the moments of inertia had to be measured precisely in order to have a stable spinning axis enabling a stable gravity simulation. Finally, the functionality had to be verified for each unit and for the system which required that several small test campaigns had to be conducted, like a solar panel deployment test and extensive software testing. A tight link to the operations teams of the German Space Operations and Control Center during such tests and beyond finally ensures the operability of the overall system in the operational phase.

Physical Systems (CPS) are becoming increasingly complex. Their development and evaluation are carried out by several teams at different sites, while the time and budget is limited. Costly delays can occur, when the interplay of subsystems is to be tested and certain hardware components are not continuously present on site. Before CPS can be put into operation, they must be tested for functionality, reliability and safety. Possible errors must be detected and corrected at an early stage, both in software and hardware. Therefore, simulators are increasingly used in the development, verification and test phase. By replacing parts of the CPS with a simulated variant, hardware and software components can be developed in parallel at different locations by various organizations. The aim of this paper is to present a distributed event-based simulation environment for CPS that is reusable across various organizations and easily expandable. The simulation is carried out with software models, which simulate the functional behavior of the CPS to be tested. Simulation models or interface adapters for hardware components can be developed using defined software interfaces, regardless of the chosen platform or programming language. They can be integrated into the simulation environment with minimal effort and executed on distributed computer systems, while the communication takes place via ZeroMQ. The simulation environment is particularly suitable for systems that require low latency to guarantee real-time performance.

Constructing good test cases is difficult and time-consuming, especially if the system under test is still under development and its exact behavior is not yet fixed. We propose a new approach to compute test strategies for reactive systems from a given temporal logic specification using formal methods. The computed strategies are guaranteed to reveal certain simple faults in every realization of the specification and for every behavior of the uncontrollable part of the system's environment. The proposed approach supports different assumptions on occurrences of faults (ranging from a single transient fault to a persistent fault) and by default aims at unveiling the weakest one. We argue that such tests are also sensitive for more complex bugs. Since the specification may not define the system behavior completely, we use reactive synthesis algorithms with partial information. The computed strategies are adaptive test strategies that react to behavior at runtime. We work out the underlying theory of adaptive test strategy synthesis and present experiments for a safety-critical component of a real-world satellite system. We demonstrate that our approach can be applied to industrial B Franz RöckFormal Methods in System Design (2019) 55: specifications and that the synthesized test strategies are capable of detecting bugs that are hard to detect with random testing.

Constructing good test cases is difficult and time-consuming, especially if the system under test is still under development and its exact behavior is not yet fixed. We propose a new approach to compute test strategies for reactive systems from a given temporal logic specification using formal methods. The computed strategies are guaranteed to reveal certain simple faults in every realization of the specification and for every behavior of the uncontrollable part of the system’s environment. The proposed approach supports different assumptions on occurrences of faults (ranging from a single transient fault to a persistent fault) and by default aims at unveiling the weakest one. We argue that such tests are also sensitive for more complex bugs. Since the specification may not define the system behavior completely, we use reactive synthesis algorithms with partial information. The computed strategies are adaptive test strategies that react to behavior at runtime. We work out the underlying theory of adaptive test strategy synthesis and present experiments for a safety-critical component of a real-world satellite system. We demonstrate that our approach can be applied to industrial specifications and that the synthesized test strategies are capable of detecting bugs that are hard to detect with random testing.

Abstract:The ownership of land has always been the important precondition for lasting socio-economic situation and the development of the country. Despite that, there is a process of learning going on in practically all the new member countries, which are still learning that productive ability of the agriculture depends in a big degree on the stability of ownership of land and its tranquil farming. Despite many fundamental and substantial differences, we can say that hitherto development in land law was tremendous. But it also follows that significant social and economic divergences have not made full liberalisation of the land market possible without "yes, but".Key words: land policy, land market, land law, selling of land to foreigners Abstrakt: Vlastnictví půdy bylo vždy důležitým předpokladem pro trvalé sociálně ekonomické poměry a vývoj země. I přesto stále ještě prakticky všechny nové členské země prochází procesem poznávání, že produkční schopnost zeměděl-ství v obzvláštní míře závisí na stabilitě vlastnictví půdy a na jejím nerušeném obhospodařování. Přes mnoho zásadních a podstatných rozdílů však lze konstatovat, že dosavadní vývoj v zemědělském právu byl ohromující. Je však také nasnadě, že závažné sociální a ekonomické divergence dosud neumožnily plnou liberalizaci trhu s půdou bez "ano, ale".Klíčová slova: půdní politika, trh s půdou, pozemkové právo, prodej půdy cizincům