Formal Compositional Semantics for Yakindu Statecharts

Many of today’s safety-critical systems are reactive, embedded systems. Their internal behavior is usually represented by state-based models. Furthermore, as the tasks carried out by such systems are getting more and more complex, there is a strong need for compositional modeling languages. Such modeling formalisms start from the component-level and use composition to build the system-level model as a collection of simple modules. There are a number of solutions supporting the model-based development of safety-critical embedded systems. One of the popular open-source tools is Yakindu, a statechart editor with a rich language and code generation capabilities. However, Yakindu so far lacks support for compositional modeling. This paper proposes a formal compositional language tailored to the semantics of Yakindu statecharts. We propose precise semantics for the composition to facilitate formal analysis and precise code generation. Based on the formal basis laid out here, we plan to build a complete tool-chain for the design and verification of component- based reactive systems

Constraint Programming with Multi-valued Decision Diagrams: A Saturation Approach

Constraint programming is a declarative way of modeling and solving optimization and satisfiability problems over finite domains. Traditional solvers use search-based strategies enhanced with various optimizations to reduce the search space. One of such techniques involves multi-valued decision diagrams (MDD) to maintain a superset of potential solutions, gradually discarding combinations of values that fail to satisfy some constraint. Instead of the relaxed MDDs representing a superset, we propose to use exact MDDs to compute the set of solutions directly without search, compactly encoding all the solutions instead of enumerating them. Our solution relies on the main idea of the saturation algorithm used in model checking to reduce the required computational cost. Preliminary results show that this strategy can keep the size of intermediate MDDs small during the computation

The effect of cyanobacterial compounds on the organogenesis of pea cultured in vitro

Many experimental results suggest the plant growth regulator (PGR) content and its physiological function in macro- and microscopic algae. Various compounds of cyanobacteria could be useful sources to enhance or substitute the influence of synthetic PGRs on tissue cultures of recalcitrant plants in vitro. In this study we have evaluated the beneficial effects of some extracellular compounds derived from axenic cultures of cyanobacteria. The cyanobacterial compounds in biomass alone have produced lower rates of shoot regeneration and gained smaller fresh weights compared to the PGRs control. They are not like real substitutes of synthetic PGRs but as a supplement in culture media resulting more vigorious cultures and regenerated shoots

Microalgal and cyanobacterial extracts in the tissue cultures of higher plants (pea, tobacco, beet)

The empirical approach that has been extensively used in studies on ABSTRACT in vitro organogenesis has shown that success is largely dependent on three factors: explant choice, medium composition, and control of the physical environment. Manipulation of these factors leads to the initiation of organized development. It is well known that the concentration and combination of growth regulators govern plant regeneration. There is accumulating evidence that some of the hormones which operate in higher plants could have similar roles in algae, even in microalgae and cyanobacteria. The in vitro culture of recalcitrant plants (such as pea, beet) needs other organic growth substances than plant hormones. In this study we have evaluated the beneficial effects of some extracellular compounds derived from axenic cultures of microalgae. The dilution of freeze-dried biomass from some microalgae and cyanobacteria could be useful for the improvement of in vitro culture media of economically important crops

Model Checking-based Software-FMEA: Assessment of Fault Tolerance and Error Detection Mechanisms

Failure Mode and Effects Analysis (FMEA) is a systematic technique to explore the possible failure modes of individual components or subsystems and determine their potential effects at the system level. Applications of FMEA are common in case of hardware and communication failures, but analyzing software failures (SW-FMEA) poses a number of challenges. Failures may originate in permanent software faults commonly called bugs, and their effects can be very subtle and hard to predict, due to the complex nature of programs. Therefore, a behavior-based automatic method to analyze the potential effects of different types of bugs is desirable. Such a method could be used to automatically build an FMEA report about the fault effects, or to evaluate different failure mitigation and detection techniques. This paper follows the latter direction, demonstrating the use of a model checking-based automated SW-FMEA approach to evaluate error detection and fault tolerance mechanisms, demonstrated on a case study inspired by safety-critical embedded operating systems

Telemetric expert system based on interent

The paper deals with the proposal of the measuring chain assigned for remote measuring in the automobile industry. The designed solution should be able to do automatic measurement of all required parameters and to send obtained data to the remote centre, where they could be analyzed by telemetric expert system

Application of algal biomass for enhanced acclimatization of orchids

Algae produce plant growth regulators (PGRs), similar to higher plants. To study this feature, freeze-dried and ultrasonicated algal biomass was applied to support the development of certain orchids. An in vitro and an ex vitro experiment were carried out. In case of Phalaenopsis and Paphiopedilum, the nutrition medium was supplemented with the biomass of five algal strains at a concentration of 0.5 gL-1 in the in vitro experiment. This treatment enhanced the development of plants, but different strains depending on orchid species proved to be efficient. In Oncidium cultures different concentrations of MACC-612 were applied as a supplementation of nutrition media. Results showed, that higher concentrations (0.5 – 1 gL-1) evolved a salutary effect on the plant growth. In the ex vitro experiment orchids were grown on algal free media under sterile conditions. After that they were potted into the greenhouse and treated eleven times with different concentrations of algal suspension. After three months of acclimatization the lower concentrations (0.1 – 0.2 gL-1) of algal biomass applied in the cultures of Phalaenopsis, Paphiopedilum and Oncidium exerted a positive effect

To Do or Not to Do: Semantics and Patterns for Do Activities in UML PSSM State Machines

State machines are used ubiquitously in engineering software-intensive systems. UML State Machines extend simple finite state machines with powerful constructs. Among the many extensions, there is one seemingly simple and innocent language construct that fundamentally changes state machines' reactive model of computation: doActivity behaviors. DoActivity behaviors describe behavior that is executed independently from the state machine once entered in a given state, typically modeling complex computation or communication as background tasks. However, the UML specification or textbooks are vague about how the doActivity behavior construct should be appropriately used. This lack of guidance is a severe issue as, when improperly used, doActivities can cause concurrent, non-deterministic bugs that are especially challenging to find and could ruin a seemingly correct software design. The Precise Semantics of UML State Machines (PSSM) specification introduced detailed operational semantics for state machines. To the best of our knowledge, there is no rigorous review yet of doActivity's semantics as specified in PSSM. We analyzed the semantics by collecting evidence from cross-checking the text of the specification, its semantic model and executable test cases, and the simulators supporting PSSM. We synthesized insights about subtle details and emergent behaviors relevant to tool developers and advanced modelers. We reported inconsistencies and missing clarifications in more than 20 issues to the standardization committee. Based on these insights, we studied 11 patterns for doActivities detailing the consequences of using a doActivity in a given situation and discussing countermeasures or alternative design choices. We hope that our analysis of the semantics and the patterns help vendors develop conformant simulators or verification tools and engineers design better state machine models