The EMI Registry: Discovering Services in a Federated World

The Distributed Computing Infrastructure (DCI) has become an indispensable tool for scientific research. Such infrastructures are composed of many independent services that are managed by autonomous service providers. The discovery of services is therefore a primary function, which is a precursor for enabling efficient workflows that utilise multiple cooperating services. As DCIs, such as the European Grid Initiative (EGI), are based on a federated model of cooperating yet autonomous service providers, a federated approach to service discovery is required that seamlessly fits into the operational and management procedures of the infrastructure. Many existing approaches rely on a centralised service registry, which is not suited to a federated deployment and operational model. A federated service registry is therefore required that is capable of scaling to handle the number of services and discovery requests found in a production DCI. In this paper we present the EMI Registry (EMIR), a decentralised architecture that supports both hierarchical and peering topologies, enabling autonomous domains to collaborate in a federated infrastructure. An EMIR pilot service is used in order to evaluate a prototype of this architecture under real-world conditions with a geographically-dispersed deployment. The results of this initial deployment are provided along with a few performance measurements.     

Electro-oculogram in multiple system and late onset cerebellar atrophies

The present investigation uses electrooculogram to evaluate multiple system atrophy (MSA) and late onset cerebellar atrophies (LOCAs), both idiopathic (ILOCA) and late onset autosomal dominant cerebellar ataxia (ADCA). Forty cases were clinically examined using scales for cerebellar, pyramidal, parkinsonian, mental status and neuroimaging quantitative evaluations. The patients were classified into three groups: olivopontocerebellar atrophy (OPCA), striatonigral degeneration (SND), Shy-Drager syndrome (SDS), and LOCA. We have used direct current electro-oculography in order to establish their validity in making the diagnosis. Cerebellar signs were significantly correlated with impaired VOR-fix gain and OKN, abnormalities of saccades, and reduced smooth pursuit gain (p < 0.05). Pons atrophy was significantly correlated with impaired VOR-fix gain (p < 0.01), abnormalities of saccades (p < 0.01), and reduced smooth pursuit gain (p < 0.05). Cerebellar hemisphere atrophy was significantly correlated only with impaired VOR-fix gain (p < 0.05), and medulla oblongata atrophy only with abnormalities of saccades (p < 0.05). Gaze-evoked nystagmus was found in 42.8% of patients with OPCA, and only in 14.2% with SND, but was not found in LOCA patients (t test, p < 0.05). In patients with OPCA, the combination of gaze-evoked nystagmus, abnormalities of sinusoidal VOR and reduced OKN gain measurements was very frequent, while infrequent in both LOCA (Fisher's exact test, p < 0.05) and SND subjects (p < 0.01). SDS also showed abnormalities of the oculomotor system.     

Performance analysis of IEEE 802.15.7-based visible light communication systems in underground mine environments

Photonic Network Communications - Underground mining (UM) is an industry worldwide known for its hostile work environment; therefore, a proper communication system is essential to preserve the...     

Omnidirectional vision applied to Unmanned Aerial Vehicles (UAVs) attitude and heading estimation

This paper presents an aircraft attitude and heading estimator using catadioptric images as a principal sensor for UAV or as a redundant system for IMU (Inertial Measure Unit) and gyro sensors. First, we explain how the unified theory for central catadioptric cameras is used for attitude and heading estimation, explaining how the skyline is projected on the catadioptric image and how it is segmented and used to calculate the UAV’s attitude. Then, we use appearance images to obtain a visual compass, and we calculate the relative rotation and heading of the aerial vehicle. Finally the tests and results using the UAV COLIBRI platform and the validation of them in real flights are presented, comparing the estimated data with the inertial values measured on board.     

New results on robust stability for differential-difference systems with affine linear parametric uncertainty

This article presents sufficient conditions to verify the robust stability property of convex combinations for quasipolynomials that represent the characteristic equation of differential-difference dynamics systems. It considers affine linear parametric uncertainty structure in the coefficients of quasipolynomials and also, interval uncertainty in the time delay. First of all, a transformation of the delay's operator is performed in order to get a two variable polynomial; after this, to obtain the robust stability property, a result based on the Hurwitz matrix is applied.     

Robust design of multi-agent system interactions: A testing approach based on pattern matching

The definition of protocols between agents is not enough for guaranteeing the absence of undesirable communication in organizations and the presence of desirable ones in large multi-agent systems (MASs). This is a consequence of the complex system nature of MASs, which cause sophisticated behaviors to arise out of a multiplicity of relatively simple interactions among the independent agents composing them. With this motivation, this paper presents an approach for testing communication in MAS architectures. In this approach, designers are not only recommended to specify the desired communication protocols, but also the undesired patterns and organization structures in the agents’ communications, allowing designers to define robust communication structures. For this purpose, this work presents (1) a language to define such patterns; (2) a set of already defined desired and undesired patterns which usually appear in general MASs; (3) a tool that allows developers to automatically detect these patterns in logs of MAS executions; and (4) a guideline that takes developers through the testing of the communications in MASs. The current approach is experienced with a case study, and the results show that the application of the current approach and the suppression of detected undesired patterns improve the effectiveness and efficiency of the corresponding MAS.     

Modular design of a hybrid genetic algorithm for a flexible job–shop scheduling problem

The aim of the job–shop scheduling problem is to optimize the task planning in an industrial plant satisfying time and technological constraints. The existing algorithmic and mathematical methods for solving this problem usually have high computational complexities making them intractable. Flexible job–shop scheduling becomes even more complex, since it allows one to assign each operation to a resource from a set of suitable ones. Alternative heuristic methods are only able to satisfy part of the constraints applicable to the problem. Moreover, these solutions usually offer little flexibility to adapt them to new requirements. This paper describes research within heuristic methods that combines genetic algorithms with repair heuristics. Firstly, it uses a genetic algorithm to provide a non-optimal solution for the problem, which does not satisfy all its constraints. Then, it applies repair heuristics to refine this solution. There are different types of heuristics, which correspond to the different types of constraints. A heuristic is intended to evaluate and slightly modify a solution that violates a constraint in a way that avoids or mitigates such violation. This approach improves the adaptability of the solution to a problem, as some changes can be addressed just modifying the considered chromosome or heuristics. The proposed solution has been tested in order to analyse its level of constraint satisfaction and its makespan, which are two of the main parameters considered in these types of problems. The paper discusses this experimentation showing the improvements over existing methods.     

Reliability Model for Electronic Devices under Time Varying Voltage

Present reliability models, which estimate the lifetime of electronic devices, work under the assumption that the voltage level must be constant when an Accelerated Life Testing is performed. Nevertheless, in a real operational environment, electronic devices are subjected to electrical variations present in the power lines; that means the voltage has a time‐varying behavior, which breaks the assumption of reliability models. Thus, in this paper, a reliability model is presented, which describes the lifetime of electronic devices under time‐varying voltage via a parametric function. The model is based on the Cumulative Damage Model with random failure rate and the modified Inverse Power Law. In order to estimate the parameters of the proposed model, the maximum likelihood method was employed. A case study based on the time‐varying voltage induced by electrical harmonics when Alternate Current/Direct Current (AC/DC) transformer is connected to the power line is presented in this paper. Copyright © 2015 John Wiley & Sons, Ltd.     

Privatisation and rehabilitation in the Budapest inner districts

Inner‐city areas of Budapest have been almost exclusively dominated by public (state‐owned) rental housing since 1952 when massive nationalisation turned private rentals into state rentals. The last four decades have shown a slow but gradual deterioration of this housing stock (except for the CBD area) due to the problems of rent policy, bureaucratic and inefficient organisation of maintenance and also the slow, but continuous, exchange of population. Even if inner‐city areas never became low prestige contagious slum areas, young families tended to leave this part of the city, moving to the new flats on state‐built housing estates or self‐help building areas. At the end of the 1980s many aspects of inner‐city housing suddenly changed and this led to a completely new scenario. By far the most important change was, however, the implementation of a Right to Buy policy which made it possible for sitting tenants to buy their units under very favourable financial terms (at a very discounted market price with the possibility of a loan with a huge interest‐rate subsidy), without real constraints on re‐sale. In the meantime, privatisation of the economy and the growing number of Hungarian and joint ventures dramatically increased the demand for office space and other commercial properties. Researchers hypothesised the speeding up of the segregation processes, and the increase in the difficulties for the rehabilitation and renewal processes in the inner city. In this paper we use the results of a recent empirical survey in order to analyse the effects of privatisation on the possibilities of rehabilitation. Particular attention is paid to the connection between privatisation and equity issues in terms of the distribution of rent subsidy and value‐gap among the different social groups.