Distributed Runtime Verification of Cyber-Physical Systems Based on Graph Pattern Matching

Cyber-physical systems process a huge amount of data coming from sensors and other information sources and they often have to provide real-time feedback and reaction. Cyber-physical systems are often critical, which means that their failure can lead to serious injuries or even loss of human lives. Ensuring correctness is an important issue, however traditional design-time verification approaches can not be applied due to the complex interaction with the changing environment, the distributed behavior and the intelligent/autonomous solutions. In this paper we present a framework for distributed runtime verification of cyber-physical systems including the solution for executing queries on a distributed model stored on multiple nodes

Abstraction-Based Model Checking of Linear Temporal Properties

Even though the expressiveness of linear temporal logic (LTL) supports engineering application, model checking of such properties is a computationally complex task and state space explosion often hinders successful verification. LTL model checking consists of constructing automata from the property and the system, generating the synchronous product of the two automata and checking its language emptiness. We propose a novel LTL model checking algorithm that uses abstraction to tackle the challenge of state space explosion. This algorithm combines the advantages of two commonly used model checking approaches, counterexample-guided abstraction refinement and automata theoretic LTL model checking. The main challenge in combining these is the refinement of "lasso"-shaped counterexamples, for which task we propose a novel refinement strategy based on interpolation

JURASSIC PALAEOGEOGRAPHY OF THE TRANSDANUBIAN CENTRAL RANGE (HUNGARY)

The Transdanubian Central Range (TCR) is a flattened range of hills in northern Transdanubia (Hungary), formed mainly by Mesozoic carbonate rocks showing strong facies similarities with the Southern Alps and the Austroalpine domain. The Jurassic system is divided into several formations of predominantly pelagic limestones. Ammonoids are frequent and were collected bed-by-bed in numerous sections, providing an excellent biostratigraphic resolution. The thickness of the Jurassic system is usually small but changes along the strike of the TCR. It reaches a maximum thickness of 500 m in the western part; is very variable (10-400 m) in the central segment (Bakony Mts.) and rather low (less than 100 m) in the east (Gerecse). In the Bakony segment, the thickness variation reflects the strongly dissected topography of the Jurassic sea-floor. Synsedimentary tectonics is dominated by normal faults; tilted blocks and listric faults may be inferred only in the east.Five main steps were identified in the palaeogeographic evolution: 1) Late Hettangian: carbonate oolitic shoals prevail, except for a few sites where non-deposition or neritic sediments occur. 2) Sinemurian and Pliensbachian: tectonic disintegration resulted in an intricate pattern of submarine horsts and intervening basins, with condensed sedimentation or non-deposition on the horsts and thicker, continuous sedimentary sequences in the basins. The submarine topographic highs are surrounded by aprons of redeposited material (scarp breccias, brachiopod coquinas, crinoidal calcarenites, spiculitic cherty limestones), while pure or argillaceous limestones (Rosso Ammonitico) prevail in the distal areas. 3) Early Toarcian: the Tethys-wide anoxic event is superimposed on the previous submarine bottom topography; the resulting black shales and sedimentary Mn-ores are concentrated on the western sides of some horsts. 4) Dogger to Early Malm: radiolarites with heterochronous lower and upper boundaries (Aalenian to Kimmeridgian) prevail, except for the top of some submarine topographic highs. The absence of uppermost Bathonian to Lower Oxfordian carbonates suggests that the whole TCR sunk below the CCD in those times. 5) Latest Jurassic: the uniform deposition of Rosso Ammonitico and Biancone in the Late Kimmeridgian and Tithonian is interrupted only in the Early Tithonian by local intercalations of scarp breccias and coarse biodetrital limestones. This is interpreted as the last manifestation of synsedimentary tectonic movements along the faults bordering the submarine horsts. Based on palaeogeographic similarities and analogies in Jurassic times, the TCR is visualized as the northern foreground of the Trento platform/plateau (lying north of the later Insubric lineament), where the block-tectonic disintegration and differential subsidence started earlier and resulted in a bottom morphology more dissected than in the South Alpine part of this west Tethyan passive margin.&nbsp

Bounded saturation-based CTL model checking

Formal verification is becoming a fundamental step of safety-critical and model-based software development. As part of the verification process, model checking is one of the current advanced techniques to analyze the behavior of a system. Symbolic model checking is an efficient approach to handling even complex models with huge state spaces. Saturation is a symbolic algorithm with a special iteration strategy, which is efficient for asynchronous models. Recent advances have resulted in many new kinds of saturation-based algorithms for state space generation and bounded state space generation and also for structural model checking. In this paper, we examine how the combination of two advanced model checking algorithms – bounded saturation and saturation-based structural model checking – can be used to verify systems. Our work is the first attempt to combine these approaches, and this way we are able to handle and examine complex or even infinite state systems. Our measurements show that we can exploit the efficiency of saturation in bounded model checking

Improving Saturation-based Bounded Model Checking

Formal verification is becoming a fundamental step in assuring the correctness of safety-critical systems. Since these systems are often asynchronous and even distributed, their verification requires methods that can deal with huge or even infinite state spaces. Model checking is one of the current techniques to analyse the behaviour of systems, as part of the verification process. In this paper a symbolic bounded model checking algorithm is presented that relies on efficient saturation-based methods. The previous approaches are extended with new bounded state space exploration strategies. In addition, constrained saturation is also introduced to improve the efficiency of bounded model checking. Our measurements confirm that these approaches do not only offer a solution to deal with infinite state spaces, but in many cases they even outperform the original methods

Kompozit anyagok törésmechanikai és dinamikai vizsgálata = Fracture mechanical and dynamical investigation of composite materials

A kutatás során a repedések, bemetszések kompozit anyagok mechanikai tulajdonságaira gyakorolt hatását vizsgáltuk. Törésmechanikai szempontból kifejlesztésre került egy olyan teszt, amely lehetővé teszi a vegyes I/III-as, II/III-as és I/II/III-as módusú rétegközi törés vizsgálatát. A kísérleti eredmények feldolgozásához analitikus modellek készültek, amelyek pontosságát végeselem modellek segítségével ellenőriztük. Megvizsgáltuk a III-as módusú repedésfeszítő erő függését a geometriai paraméterektől. A repedési folyamat stabilitásának vizsgálatára kidolgozásra került egy kísérleti alapú kritérium, amelyet számos próbatest típuson alkalmaztunk, illetve hasznosságát bemutattuk. Megépült a vegyes módusú hajlító próbatest befogója (mixed-mode bending), amelyet eredményesen alkalmaztunk kompozit próbatestekre. Elvégzésre került a repedéssel ellátott kompozit rudak rezgésmérése, amely során mérés alapján meghatároztuk a sajátfrekvenciákat és lengésképeket. Analitikus modellekkel kimutattuk, hogy zárt repedés esetén a rúd delaminált szakaszán periodikus erővel nyomott/húzott rudak rezgéseiről van szó. A Kirchhoff-féle lemezelmélet felhasználásával meghatároztuk a delaminált lemezekben ébredő rétegközi nyírófeszültségeket leíró differenciálegyenlet-rendszert és megoldottuk azt egy egyszerűen alátámasztott, rugalmas lemezre. Megmutattuk, hogy lemezek esetében a rezgés során szintén periodikus erővel húzott/nyomott lemezekről van szó. | In this research project the effect of cracks and delaminations on the mechanical properties of composite materials have been investigated. A novel fracture mechanical system has been developed which makes it possible to measure the mixed-mode I/III, II/III and I/II/III interlaminar fracture toughness of composites. To reduce the experimental data analytical models have been developed, their accuracy has been verified by finite element models. The influence of geometrical parameters on the mode-III energy release rate has been analyzed. A novel experiment-based criterion has been developed for the crack propagation in composite specimens, the criterion has been applied to several configurations, its applicability has been demonstrated. The rig of the mixed-mode bending specimen has been constructed, which has been successfully applied to composite coupons. We have performed the vibration analysis of delaminated composite beams, i.e. we have determined the eigenfrequencies and mode shapes of the beams. It has been shown by using analytical models that in the case of closed delamination in the cracked part, the beams are loaded by periodic tensile and compressive forces. Using the Kirchhoff plate theory the governing differential equations of the interlaminat shear stresses have been derived and solved for a simply-supported elastic plate. It has been highlighted that the vibration of delaminated plates the cracked part involves periodic tensile and compressive forces

Számítógéppel segített tervezés csonttörések műtéti helyreállítására = Computer aided planing for surgical reconstruction of fractures

A vázrendszer sérülései lehetnek igen komplexek és ellátásuk nagy pontosságot igényelhet. Kézenfekvőnek tűnik, hogy a sebészi beavatkozás előtt egy geometriai és mechanikai modellen a különböző fixációs lehetőségek kipróbálásra kerülhessenek. Ennek érdekében egy computerizált rendszert hoztunk létre, melyet MedEdit-nek neveztünk el azért, hogy a sebész műtét előtt megtervezhesse és lemérhesse a tervezett rögzitési lehetőségeket. Végeselemes analízist használva a módosítások összehasonlíthatók. A rendszer bevezetésre került és működik. Bizonyos pontoknál még felhasználói interakcióra van szükség. A geometriai és a mechanikai modell elkészítése kb. 5 percig tart, beleértve az interakciókat is. A végeselemes analízis durván hat percet igényel ( 2 Ghz-es computeren 1,5 GB memóriával). A sterssz analízis korrelál a klinikai elvárással, a kvantitatív kalibrálás elkészült. | Surgeries of the skeletal trauma can be highly complex and require extreme accuracy. That is why it seems to be practical that prior to a surgical intervention a geometric and mechanic model has to be prepared, which can be used to simulate various surgical options. A computerized system, called MedEdit was created, to help the surgeon to plan the intervention. Using of Finite Element Analysis (FEA), the modifications can be measured or compared before the surgery. The system is implemented and works. It is able to perform all tasks, but there are still points where some user interaction is needed. Generally, the geometric and mechanical model can be created s in ca. 5 minutes including the user interactions. The FEA takes roughly 6 minutes for a pelvis 3D volume study (on a 2 GHz computer with 1,5 GB memory). Our stress results seem to match the clinical expectations, quantitative calibration and measurements were done