ARPHA: an FDIR architecture for Autonomous Spacecrafts based on Dynamic Probabilistic Graphical Models

This paper introduces a formal architecture for on-board diagnosis, prognosis and recovery called ARPHA. ARPHA is designed as part of the ESA/ESTEC study called VERIFIM (Veri\ufb01cation of Failure Impact by Model checking). The goal is to allow the design of an innovative on-board FDIR process for autonomous systems, able to deal with uncertain system/environment interactions, uncertain dynamic system evolution, partial observability and detection of recovery actions taking into account imminent failures. We show how the model needed by ARPHA can be built through a standard fault analysis phase, \ufb01nally producing an extended version of a fault tree called EDFT; we discuss how EDFT can be adopted as a formal language to represent the needed FDIR knowledge, that can be compiled into a corresponding Dynamic Decision Network to be used for the analysis. We also discuss the software architecture we are implementing following this approach, where on-board FDIR can be implemented by exploiting on-line inference based on the junction tree approach typical of probabilisticgraphical models

SAN models of a benchmark on dynamic reliability

This report provides the detailed description of the Stochastic Activity Network (SAN) models appearing in [1] and concerning a benchmark on dynamic reliability taken from the literature

Simulating the communication of commands and signals in a distribution grid

The report presents the simulation of communication scenarios involving one area control centre and a set of substations inside a distribution grid of the Electrical Power System. In such scenarios, the communication is affected by threats different from those under exam in [1, 2]; in particular, here, we consider the denial of service attack to the communication network, and the temporary internal failure of a subset of substations. The scenarios have been modeled and simulated in form of Stochastic Activity Networks (SAN); the goal is the evaluation of the impact of the threats, on the communication reliability

SAN models of communication scenarios inside the Electrical Power System

This report provides all the details about the models and the quantitative results presented in [1], about the simulation of communication scenarios inside the Electrical Power System. In particular, the scenarios deal with the communication between one area control centre and a set of substations in a distribution grid, exchanging commands and signals by means of a redundant communication network. The communication may be affected by threats such as the communication network failure, or intrusions into the communication, causing the loss of commands or signals. The scenarios have been modeled and simulated in form of Stochastic Activity Networks, with the purpose of evaluating the effects of such threats on the communication reliability

A GSPN semantics for Continuous Time Bayesian Networks with Immediate Nodes

In this report we present an extension to Continuous Time Bayesian Networks (CTBN) called Generalized Continuous Time Bayesian Networks (GCTBN). The formalism allows one to model, in addition to continuous time delayed variables (with exponentially distributed transition rates), also non delayed or "immediate" variables, which act as standard chance nodes in a Bayesian Network. This allows the modeling of processes having both a continuous-time temporal component and an immediate (i.e. non-delayed) component capturing the logical/probabilistic interactions among the model\u2019s variables. The usefulness of this kind of model is discussed through an example concerning the reliability of a simple component-based system. A semantic model of GCTBNs, based on the formalism of Generalized Stochastic Petri Nets (GSPN) is outlined, whose purpose is twofold: to provide a well-de\ufb01ned semantics for GCTBNs in terms of the underlying stochastic process, and to provide an actual mean to perform inference (both prediction and smoothing) on GCTBNs. The example case study is then used, in order to highlight the exploitation of GSPN analysis for posterior probability computation on the GCTBN model

Ancient Tahitian Society

“Tahiti is far famed yet too little known.” Thus wrote J. M. Orsmond in 1848, and the same assertion can be made in 1972. Thousands of pages had been published about Tahiti and its neighboring islands when Orsmond uttered his judgment, and tens of thousands have been published since that time, but a unified, comprehensive, and detailed description of the pre-European ways of life of the inhabitants of those Islands is yet to appear in print. The present work, lengthy as it is, makes no such claim to comprehensiveness; rather, it is concerned mainly with the social relations of those inhabitants, and it serves up only enough about their technology, their religion, their aesthetic expressions, and so forth to place descriptions of their social relations in context and render them more comprehensible. Volumes 1 and 2 of this work are a reconstruction of the Islanders’ way of life as it was believed to have been just before it began to be transformed by European influence—a period labeled the Late Indigenous Era. Volume 3 covers events in Tahiti and Mo‘orea from about 1767 to 1815—a period labeled the Early European Era

Rapan lifeways : society and history on a Polynesian island

ix, 227 p. : ill. ; 22 cm. Includes index. Bibliography: p. 219-224.This edition originally published: Prospect Heights, IL : Waveland Press, [1983, c1970]Published in 1970 by Little, Brown & Co. of Bosto

Topics in Polynesian language and culture history

This book is a revised version of a doctoral thesis submitted to the Department of Linguistics, Research School of Pacific and Asian Studies, The Australian National University, under the title Polynesian language and culture history. The thesis was developed over a five-year period, 1 992 to 1 996. During the first year I settled upon a topic and began studying East Polynesian reconstructions in Biggs ' Pollex. By about mid 1 99 3 (Marck 1 996a) I was impressed with the extent o f sporadic sound changes among the established East Polynesian subgroups. I became interested in the idea that the older, higher order subgroups of Polynesian could be reexamined with an eye towards u niquely shared sporadic sound changes to see if any refinements in the standard subgrouping might be achieved. During the year to mid 1 994 I found that the Ellicean Outliers shared sporadic sound changes with East Polynesian and Samoan that other Polynesian languages did not share (Marck 1 999), a stunning bit of support for Wilson's (1 9 8 5 ) suggestion of "Ellicean", composed of those same languages, on the basis of the pronoun prehistory. I then turned to a year of work on cosmogony (Marck 1996b, 1996c) and then a year on kin terms (Marck 1 996d). I consolidated those and other materials into the submitted thesis in late 1997