Real-time auditing of domotic robotic cleaners

Domotic Robotic Cleaners are autonomous devices that are designed to operate almost entirely unattended. In this paper we propose a system that aims to evaluate the performance of such devices by analysis of their trails. This concept of trails is central to our approach, and it encompasses the traditional notion of a path followed by a robot between arbitrary numbers of points in a physical space. We enrich trails with context-specific metadata, such as proximity to landmarks, frequency of visitation, duration, etc. We then process the trail data collected by the robots, we store it an appropriate data structure and derive useful statistical information from the raw data. The usefulness of the derived information is twofold: it can primarily be used to audit the performance of the robotic cleaner –for example, to give an accurate indication of how well a space is covered (cleaned). And secondarily information can be analyzed in real-time to affect the behavior of specific robots – for example to notify a robot that specific areas have not been adequately covered. Towards our first goal, we have developed and evaluated a prototype of our system that uses a particular commercially available robotic cleaner. Our implementation deploys adhoc wireless local networking capability available through a surrogate device mounted onto this commodity robot; the device senses relative proximity to a grid of RFID tags attached to the floor. We report on the performance of this system in experiments conducted in a laboratory environment, which highlight the advantages and limitations of our approach

Escalation: complex event detection in wireless sensor networks

We present a new approach for the detection of complex events in Wireless Sensor Networks. Complex events are sets of data points that correspond to interesting or unusual patterns in the underlying phenomenon that the network monitors. Our approach is inspired from time-series data mining techniques and transforms a stream of real-valued sensor readings into a symbolic representation. Complex event detection is then performed using distance metrics, allowing us to detect events that are difficult or even impossible to describe using traditional declarative SQL-like languages and thresholds. We have tested our approach with four distinct data sets and the experimental results were encouraging in all cases. We have implemented our approach for the TinyOS and Contiki Operating Systems, for the Sky mote platform

Efficient pattern detection in extremely resource-constrained devices

We present a novel approach for the on-line detection of Complex Events in Wireless Sensor Networks. Complex Events are sets of data points that correspond to unusual patterns that can not be detected using threshold-based techniques. Our method uses an efficient implementation of SAX, a mature data mining algorithm, that transforms a stream of readings into a symbolic representation. Complex Event Detection is then performed via four alternative modes: (a.) multiple pattern detection using a suffix array, (b.) distance-based comparison, (c.) unknown pattern detection, and (d.) probabilistic detection. The method allows users to specify complex events as patterns or to search for interesting changes without supplying any information. The appropriateness of the approach has been verified by applying it to four sensor data sets. In addition, we have developed an efficient implementation for the TinyOS operating system, and further validated our assertions by collecting and analyzing data in real-time

Estimation of pollutant-emitting point-sources using resource-constrained sensor networks

We present an algorithm that makes an appropriate use of a Kalman filter combined with a geometric computation with respect to the localisation of a pollutant-emitting point source. Assuming resource-constrained inexpensive nodes and no specific placement distance to the source, our approach has been shown to perform well in estimating the coordinates and intensity of a source. Using local gossip to directionally propagate estimates, our algorithm initiates a real-time exchange of information that has as an ultimate goal to lead a packet from a node that initially sensed the event to a destination that is as close to the source as possible. The coordinates and intensity measurement of the destination comprise the final estimate. In this paper, we assert that this low-overhead coarse localisation method can rival more sophisticated and computationally-hungry solutions to the source estimation problem

Ubiquitous computing and databases

The concept of the so-called ubiquitous computing was introduced in the early 1990s as the third wave of computing to follow the eras of the mainframe and the personal computer. Unlike previous technology generations, ubiquitous computing recedes into the background of everyday life: It activates the world, makes computers so imbedded, so fitting, so natural, that we use it without even thinking about it, and is invisible, everywhere computing that does not live on a personal device of any sort, but is in the woodwork everywhere. (Weiser & Brown, 1997, p. 81

Active rules for sensor databases

Recent years have witnessed a rapidly growing interest in query processing in sensor and actuator networks. This is mainly due to the increased awareness of query processing as the most appropriate computational paradigm for a wide range of sensor network applications, such as environmental monitoring. In this paper we propose a second database technology, namely active rules, that provides a natural computational paradigm for sensor network applications which require reactive behavior, such as security management and rapid forest fire response. Like query processing, efficient and effective active rule execution mechanisms have to address several technical challenges including language design, data aggregation, data verification, robustness under topology changes, routing, power management and many more. Nonetheless, active rules change the context and the requirements of these issues and hence a new set of solutions is appropriate. To this end, we outline the implications of active rules for sensor networks and contrast these against query processing. We then proceed to discuss work in progress carried out in project Asene that aims to effectively address these issues. Finally, we introduce our architecture for a decentralized event broker based on the publish/subscribe paradigm and our early design of an ECA language for sensor networks

Active rules for wireless networks of sensors & actuators

The last few years have witnessed a flurry of research in the field of query processing for networks of sensors and actuators. It is widely accepted that query processing is the method of choice for acquiring data from a sensor field. Although query processing offers a very good computational model for a variety of applications such as environmental monitoring, it is a poor match for application scenarios where a timely response to an event is required by the system. With this in mind, we propose a mature database technology, namely active rules, that provides a natural computational paradigm for sensor network applications that require reactive behavior, such as rapid forest fire response and security management. For the remainder of this paper we will outline the implications of active rules for sensor networks and contrast these against query processing. We will then proceed to discuss work in progress carried out by project Asene (Active SEnsor NEtworks) that aims to address these implications. We conclude by introducing our architecture for a decentralised event broker based on the publish/subscribe paradigm and our early design of an Event-Condition-Action (ECA) language for sensor networks

L'Oracional hispànic de Verona i la topografia cristiana de Tarraco a l'Antiguitat cristiana: possibilitats i límits

L'Oracional hispanic de Verona ha estat sempre referencia obligada per als estudis de topografia de l'Antiguitat tardana a Tarragona. L'estudi intenta conjugar la litúrgia amb l'arqueologia per a coneixer l'emplaçament de les esglésies de Tarraco vers el 700. L'analisi litúrgica de l'Oracional no només permet assegurar que les conegudes rubriques de les processons del diumenge de Carnestoltes no pertanyen a l'ordo catedral, sinó que, també, permet identificar una quarta església -a més de les de Sant Fructuós, Sant Pere i la Catedral-, per a la qual va ser adaptat el Codex Veronensis i que, probablement, estava advocada a sant Hipolit. També és novedosa la proposta per a l'emplaçament de l'església de Sant Pere, en una volta de la capçalera oriental del Circ -desafectat de la seva funció com a edifici d'espectacles- que argumentem mitjançant un text de 1174 del Diplomatari de Poblet