A mobile detector for measurements of the atmospheric muon flux in underground sites

Muons comprise an important contribution of the natural radiation dose in air (approx. 30 nSv/h of a total dose rate of 65-130 nSv/h), as well as in underground sites even when the flux and relative contribution are significantly reduced. The flux of muons observed underground can be used as an estimator for the depth in mwe (meter water equivalent) of the underground site. The water equivalent depth is important information to devise physics experiments feasible for a specific site. A mobile detector for performing measurements of the muon flux was developed in IFIN-HH, Bucharest. Consisting of two scintillator plates (approx. 0.9 m²) which measure in coincidence, the detector is installed on a van which facilitates measurements at different locations at the surface or underground. The detector was used to determine muon fluxes at different sites in Romania. In particular, data were taken and the values of meter water equivalents were assessed for several locations at the salt mine in Slanic-Prahova, Romania. The measurements have been performed in two different galleries of the Slanic mine at different depths. In order to test the stability of the method, also measurements of the muon flux at the surface at different elevations were performed. The results were compared with predictions of Monte-Carlo simulations using the CORSIKA and MUSIC codes.     

A cross-layer SSO solution for federating access to kerberized services in the eduroam/DAMe network

Eduroam has become one of the main examples of network federations around the world, where hundred of institutions allow roaming end users to access the local network if they belong to any other eduroam member institution. In this context, this paper proposes how, once the end user is authenticated by the network, she can access additional federated application services (beyond the web) by means of Kerberos, without deploying additional cross-realm infrastructures. With the support of existing eduroam architecture, this proposal prevents the end user from being fully authenticated by her home institution again to access the application services, which do not need to be modified. Finally, optional advanced authorization can be used to provide added value services to end users.     

Continuation-Passing C, compiling threads to events through continuations

In this paper, we introduce Continuation Passing C (CPC), a programming language for concurrent systems in which native and cooperative threads are unified and presented to the programmer as a single abstraction. The CPC compiler uses a compilation technique, based on the CPS transform, that yields efficient code and an extremely lightweight representation for contexts. We provide a proof of the correctness of our compilation scheme. We show in particular that lambda-lifting, a common compilation technique for functional languages, is also correct in an imperative language like C, under some conditions enforced by the CPC compiler. The current CPC compiler is mature enough to write substantial programs such as Hekate, a highly concurrent BitTorrent seeder. Our benchmark results show that CPC is as efficient, while using significantly less space, as the most efficient thread libraries available.     

Stability of polyphenolic extracts from grape seeds after thermal treatments

Five commercial grape seed extracts (GSEs) were put under pasteurisation (HTST and LTLT), cooking, baking and sterilisation conditions. After each treatment, the tannin content, antioxidant activity, browning and characteristics of eight phenolic compounds were determined. For nearly all quantified parameters, significant differences (p < 0.05) were found between at least two treatments. The gallic acid, gallocatechin and browning parameters showed a greater tendency to increase in the treatments, and the antioxidant activity showed a greater tendency to decrease. A positive correlation between the tannin content and browning and a negative correlation between the gallic acid and antioxidant activity were found. The GSEs were clearly grouped based on their composition; nevertheless, a grouping based on the treatments did not exist. It can be concluded that the thermal treatments affected the stability of all GSEs in a different manner depending on the phenolic profile of each extract.     

Size distribution and waiting times for the avalanches of the Cell Network Model of Fracture

The Cell Network Model is a fracture model recently introduced that resembles the microscopical structure and drying process of the parenchymatous tissue of the Bamboo Guadua angustifolia. The model exhibits a power-law distribution of avalanche sizes, with exponent −3.0 when the breaking thresholds are randomly distributed with uniform probability density. Hereby we show that the same exponent also holds when the breaking thresholds obey a broad set of Weibull distributions, and that the humidity decrements between successive avalanches (the equivalent to waiting times for this model) follow in all cases an exponential distribution. Moreover, the fraction of remaining junctures shows an exponential decay in time. In addition, introducing partial breakings and cumulative damages induces a crossover behavior between two power-laws in the histogram of avalanche sizes. This results support the idea that the Cell Network Model may be in the same universality class as the Random Fuse Model.     

A Robust and Efficient Message Passing Library for Volunteer Computing Environments

The objective of this research is to convert ordinary idle PCs into virtual clusters for executing parallel applications. The paper presents VolpexMPI that is designed to enable seamless forward application progress in the presence of frequent node failures as well as dynamically changing networks and node execution speeds. Process replication is employed to provide robustness. The central challenge in the design of VolpexMPI is to efficiently and automatically manage dynamically varying number of process replicas in different states of execution progress. The key fault tolerance technique employed is fully distributed sender based logging. The paper presents the design and an implementation of VolpexMPI. Preliminary results validate that the overhead of providing robustness is modest for applications with a favorable ratio of communication to computation and a low degree of communication.     

Pollux: a dynamic hybrid control architecture for flexible job shop systems

Nowadays, manufacturing control systems can respond more effectively to exigent market requirements and real-time demands. Indeed, they take advantage of changing their structural and behavioural arrangements to tailor the control solution from a diverse set of feasible configurations. However, the challenge of this approach is to determine efficient mechanisms that dynamically optimise the configuration between different architectures. This paper presents a dynamic hybrid control architecture that integrates a switching mechanism to control changes at both structural and behavioural level. The switching mechanism is based on a genetic algorithm and strives to find the most suitable operating mode of the architecture with regard to optimality and reactivity. The proposed approach was tested in a real flexible job shop to demonstrate the applicability and efficiency of including an optimisation algorithm in the switching process of a dynamic hybrid control architecture.