117 research outputs found
Variability Abstraction and Refinement for Game-Based Lifted Model Checking of Full CTL
One of the most promising approaches to fighting the configuration space explosion problem in lifted model checking are variability abstractions. In this work, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. The practicality of this approach is demonstrated on several variability models
Information Security as Strategic (In)effectivity
Security of information flow is commonly understood as preventing any
information leakage, regardless of how grave or harmless consequences the
leakage can have. In this work, we suggest that information security is not a
goal in itself, but rather a means of preventing potential attackers from
compromising the correct behavior of the system. To formalize this, we first
show how two information flows can be compared by looking at the adversary's
ability to harm the system. Then, we propose that the information flow in a
system is effectively information-secure if it does not allow for more harm
than its idealized variant based on the classical notion of noninterference
Groundwater residence time in the Kulnura-Mangrove Mountain Plateau (Gosford, NSW, Australia)
The Kulnura-Mangrove Mountain plateau consists of
the catchments of Mangrove, Narara, Mooney Mooney,
and Ourimbah Creeks, and Wyong River. Groundwater
plays a key role in sustaining stream flow within these
catchments. Estimates indicate up to 50% of annual
stream flow is derived from baseflow.
The local community water supply relies on the
groundwater within the elevated Hawkesbury-
Narrabeen sandstone plateau. Furthermore, the
Gosford-Wyong Councils’ Water Authority (WSA) is the
third largest in NSW and utilises many of the streams
flowing from the sandstone plateau for municipal water
supply. It is anticipated that the WSA will provide
municipal water for 319 000 persons by the year 2010.
The increasing volumes of groundwater being extracted
and changing land use have the potential to cause
damage to the fresh water aquifer through
contamination and aquifer depletion.
A hydrogeochemical survey (2006-2009) has been
conducted in NSW Dept of Water and Energy (DWE)
monitoring wells across the plateau in order to
determine groundwater residence times. Groundwater
was analysed for major ions, minor and trace elements,
H2O 18O and 2H, 13CDIC, 87Sr/86Sr, 14CDIC, and 3H,
and complemented with mineralogical and isotopic
information obtained from soil and drill chips collected
during well construction. Water stable isotopes confirm
the meteoric origin of the groundwater with most values
plotting on the local meteoric water line. Localised
evaporative trends suggest recharge with evaporated
groundwater stored in ponds.
Shallow groundwaters have 3H and 14C activities
consistent with modern recharge (Fig 1). Carbon “bomb
pulse” signatures of up to 116.8 pmC are found in the
central areas of the plateau. The thin soils, lack of
carbonates in the intensely weathered near-surface
Hawkesbury sandstone, and the shallow depth of the
water samples is consistent with the 3H results
measured, suggesting minimal dilution of the original
14C. Input of this data into a southern hemisphere bomb
pulse model [1] suggest potential recharge during the
1990´s, coinciding with sustained wet conditions and
above average rainfalls experienced during this period.
Fig. 1. 14C vs 3H plot of groundwater samples in the Kulnura-
Mangrove Mountain Plateau
Deeper groundwaters have lower 14C and 3H activities
in some cases close to background level (Fig. 1). The
quantifiable 3H suggests residence times of <70 a.
However, non-corrected 14C residence times are submodern
(>500 a). This apparent discrepancy can be
explained by either mixing with older waters or
dissolution of carbonates. The good correlation of total
dissolved inorganic carbon (TDIC) and Ca (R2=0.8),
13CTDIC in groundwater and mineralogy results from
drill chips suggest that dissolution of dispersed
carbonates is taking place.
The deepest groundwaters show the most difference in
residence time across the study area. The eastern and
western plateaus yield old groundwater with 14C
corrected residence times of around 9 ka and 4 ka
respectively. However, the groundwater at equivalent
depths in the central plateau was found to be
considerably younger with residence times of <70 a
Fractional diffusions with time-varying coefficients
This paper is concerned with the fractionalized diffusion equations governing
the law of the fractional Brownian motion . We obtain solutions of
these equations which are probability laws extending that of . Our
analysis is based on McBride fractional operators generalizing the hyper-Bessel
operators and converting their fractional power into
Erd\'elyi--Kober fractional integrals. We study also probabilistic properties
of the r.v.'s whose distributions satisfy space-time fractional equations
involving Caputo and Riesz fractional derivatives. Some results emerging from
the analysis of fractional equations with time-varying coefficients have the
form of distributions of time-changed r.v.'s
One-Dimensional and Multi-Dimensional Integral Transforms of Buschman–Erdélyi Type with Legendre Functions in Kernels
This paper consists of two parts. In the first part we give a brief survey of results on Buschman–Erdélyi operators, which are transmutations for the Bessel singular operator. Main properties and applications of Buschman–Erdélyi operators are outlined. In the second part of the paper we consider multi-dimensional integral transforms of Buschman–Erdélyi type with Legendre functions in kernels. Complete proofs are given in this part, main tools are based on Mellin transform properties and usage of Fox H-functions
More Scalable LTL Model Checking via Discovering Design-Space Dependencies (D3)
Modern system design often requires comparing several models over a large design space. Different models arise out of a need to weigh different design choices, to check core capabilities of versions with varying features, or to analyze a future version against previous ones. Model checking can compare different models; however, applying model checking off-the-shelf may not scale due to the large size of the design space for today’s complex systems. We exploit relationships between different models of the same (or related) systems to optimize the model-checking search. Our algorithm, D3 , preprocesses the design space and checks fewer model-checking instances, e.g., using nuXmv. It automatically prunes the search space by reducing both the number of models to check, and the number of LTL properties that need to be checked for each model in order to provide the complete model-checking verdict for every individual model-property pair. We formalize heuristics that improve the performance of D3 . We demonstrate the scalability of D3 by extensive experimental evaluation, e.g., by checking 1,620 real-life models for NASA’s NextGen air traffic control system. Compared to checking each model-property pair individually, D3 is up to 9.4 × faster
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