A Path Construction Algorithm for Translation Validation Using PRES+ Models

Multi-core and multi-processor architectures have predominated the domain of embedded systems permitting easy mapping of concurrent applications to such architectures. The programs, in general, are subjected to significant optimizing and parallelizing transformations, automated and also human guided, before being mapped to an architecture. Modelling parallel behaviour and formally verifying that their functionality is preserved during synthesis are challenging tasks. Untimed PRES+ models are found to be suitable for the specification of parallel behaviour. Path cover oriented equivalence checking methods have been found to be quite effective for sequential behaviour. Path construction for parallel behaviour, however, is significantly more complex than that for sequential behaviour due to all possible interleavings of the parallel operations. Identification of the path covers depends upon choosing appropriate cut-points. In this paper, the need for introducing cut-points dynamically has been underlined and a mechanism to achieve this task is proposed. Details on how to construct a path cover using dynamic cut-points is presented.

Parallelization of DEM-LBM Using Domain Decomposition

The coupled Discrete Element (DEM) - Lattice Boltzmann Method (LBM) often suffers from the high computational cost due to the fine meshes used. The intrinsic parallel nature of DEM-LBM makes it possible to be applied to the analysis of realistic engineering problems using parallel computer. In this paper the domain decomposition is implemented in the validated coupled DEM-LBM code FPS-BHAM and its performance is tested. A parallel efficiency of 0.72 has been achieved by using 32 processors, which shows a very good parallel behaviour of the DEM-LBM. Besides, the feature of ‘pseudo-vector processing capacity’ boosts the parallel behaviour of LBM with domain decomposition.

Evaluation of Scavenger Properties of some Flavonoidic Vegetal Extracts Obtained from Crataegus monogyna Jacq.

The scavenger properties of some flavonoidic vegetal extracts obtained from Crataegus monogyna Jacq have been studied using the chemiluminescence technique and ex vivo lipid peroxidation assay. A correlation between antioxidant activity and phenolic/flavonoidic content was observed for all the seven extracts, and a parallel behaviour with the antioxidant activity determinated by ex vivo lipid peroxidation assay and in vitro chemiluminescence tests was also noted.

Algorithm + strategy = parallelism

The process of writing large parallel programs is complicated by the need to specify both the parallel behaviour of the program and the algorithm that is to be used to compute its result. This paper introduces evaluation strategies: lazy higher-order functions that control the parallel evaluation of non-strict functional languages. Using evaluation strategies, it is possible to achieve a clean separation between algorithmic and behavioural code. The result is enhanced clarity and shorter parallel programs. Evaluation strategies are a very general concept: this paper shows how they can be used to model a wide range of commonly used programming paradigms, including divide-and-conquer parallelism, pipeline parallelism, producer/consumer parallelism, and data-oriented parallelism. Because they are based on unrestricted higher-order functions, they can also capture irregular parallel structures. Evaluation strategies are not just of theoretical interest: they have evolved out of our experience in parallelising several large-scale parallel applications, where they have proved invaluable in helping to manage the complexities of parallel behaviour. Some of these applications are described in detail here. The largest application we have studied to date, Lolita, is a 40,000 line natural language engineering system. Initial results show that for these programs we can achieve acceptable parallel performance, for relatively little programming effort.

The Dark Massive Halo in the Elliptical Galaxy NGC 5266

Recent observations with the Australia Telescope reveal that the elliptical galaxy NGC 5266 has a disk like structure of neutral hydrogen extending as far as almost 10 Re which approximatively lies along the galaxy's major axis, at 65° apart from the inner minor–axis dust lane (Varnas et al 1987). From the present data is not clear whether the HI structure and the dust lane are two distinct disks or a single warped structure. The regularity of the velocity field of the HI structure allow us to use it as a probe of the potential of NGC 5266. The velocity curve along the major axis is flat till the last measured point (rmax ~ 10′) at Vrot = 200km/s. Assuming that the gas in moving in circular orbits, we can derive the mass of the galaxy inside to this radius. The mass–to–light ratio M/LB rises from about 3 in the central regions to 12 at 9 Re (D = 57.6 Mpc), thus indicating that NGC 5266 is embedded in a dark massive halo. Moreover the representative point (cumulative M/LB within the last measured point) of NGC 5266 in the diagram log(M/LB) – log(Re) falls well within the region characteristic of spiral galaxies (Figure 2, Bertola et al. 1993), as do ellipticals previously studied in HI, thus reinforcing the suggestion (Bertola et al. 1993) of a parallel behaviour of the dark matter in elliptical and spiral galaxies.