Abstract

Abstract
The coordinated use of multiple Autonomous Underwater Vehicles can provide important advantages for oceanographic missions. One important mission application scenario can be the search of underwater plumes such as sources of freshwater of hydrotermal vents. These plumes characterize the environment by creating a gradient field of some measurable physical quantity. An innovative integrated acoustic navigation system and coordination control maneuver for a formation of 3 AUVs and I surface craft to gradient search and following missions is proposed. The specific formation geometry and topology takes in account the navigation and coordination requirements. It was designed to achieve an efficient, low cost and technically feasible solution. The system can operate in 3 modes depending on formation distances. Varying pinging rates and offsets are used to communicate parameters and mode changing. No additional underwater communication systems neither acoustic transponder deployment are needed for the vehicle coordination. This way a high degree of energy efficiency and overall mission low cost and simpler logistics is achieved. The hybrid nature of the coordinating maneuver allows the formation gradient survey and following with the efficient exploitation of the environment structuring by the phenomena to be studied. The individual control laws were designed in order to minimize the inter-vehicle communication. The coordination factors are the knowledge by the vehicles of each other behavior (since all vehicles execute the same control laws) and the detection of formation distortions. These distortions are detected by the relative navigation system. The proposed approach allows the low cost implementation of a multiple AUV coordinating control for a large range of oceanographic missions.

Abstract
In this paper it is studied and analyzed the impact of different security performance indices on a contingency screening and ranking algorithm. The proposed filtering technique consists of three modules, with different complexity levels. The contingencies are ranked in accordance with severity indices that allow assessing the influence of the overloads and voltage limit violations in the power network. The developed software package was applied to the IEEE 118 Test Power System. The simulation results that were produced using two different sets of security indices were compared, showing a satisfactory agreement The simulation was carried out considering a monotonous increase of the load level as well as a random one. For the different solutions the computing times were also obtained. Finally, some conclusions that provide a valuable contribution to the understanding of the Electric Power System security analysis are pointed out. © 2003 IEEE.

Abstract
The latest technological developments on electronics, mechanics, optics, and other areas have made possible the availability of low cost and high performance sensors for navigation. This opens doors to the development of high accuracy navigation systems to be used on low cost small size underwater vehicles. This paper describes th development and implementation of the navigation system for the remotely operated vehicle (ROV) of the IES Project.

Abstract
In this article we propose a role based model for the specification of organized collective agency, based on the legal concept of artificial person and on the normative perspective of organizational systems. We focus on the analysis of groups of agents ( humans or not) that want to act collectively in a ( more or less) permanent basis, and in a stable and organized way, as it is the typical case of organizations. We argue that in those cases such groups of agents should give rise to a new agent, that we call of institutionalized agent, with its own identity, whose structure is essentially defined through the characterization of a set of roles and whose behavior is determined by the acts of the agents that play such roles. We also present a deontic and action modal logic that captures the concept of acting in a role and relates it with the deontic notions of obligation, permission and prohibition. This logic is used in the formal specification of institutionalized agents and of societies of agents and in the rigorous analysis of them. We pay particular attention to the interaction between agents through contracts or other normative relations. A high level specification language is also suggested.

Abstract
The main objective of this work is to investigate the correlation between meditation stages and the hypnagogic stages of sleep and awakening. It reports the study on the brain electric activity during Yôga Svásthya meditation stages. These data were obtained by means of scalp electroencephalograms (EEGs), and confronted with the stages of meditation and hypnagogic EEG stages. The latter were based on established criteria through the study of the duration of individual occurrences of each of the nine considered hypnagogic EEG stages. Analysis made concerns time, frequency, power and signal amplitude. The results show that meditation stages reach only the first two hypnagogic EEG stages, and the spectral analysis of the EEG confirmed a dominance of rapid rhythms (beta) while the presence of lower ones (delta and theta) are not significant.