Efficient aggregate computations in large-scale dense wireless sensor networks

Tese de doutoramento em InformáticaAssuming a world where we can be surrounded by hundreds or even thousands of inexpensive computing nodes densely deployed, each one with sensing and wireless communication capabilities, the problem of efficiently dealing with the enormous amount of information generated by those nodes emerges as a major challenge. The research in this dissertation addresses this challenge. This research work proves that it is possible to obtain aggregate quantities with a timecomplexity that is independent of the number of nodes, or grows very slowly as the number of nodes increases. This is achieved by co-designing the distributed algorithms for obtaining aggregate quantities and the underlying communication system. This work describes (i) the design and implementation of a prioritized medium access control (MAC) protocol which enforces strict priorities over wireless channels and (ii) the algorithms that allow exploiting this MAC protocol to obtain the minimum (MIN), maximum (MAX) and interpolation of sensor values with a time-complexity that is independent of the number of nodes deployed, whereas other state-of-the-art approaches have a time-complexity that is dependent on the number of nodes. These techniques also enable to efficiently obtain estimates of the number of nodes (COUNT) and the median of the sensor values (MEDIAN). The novel approach proposed to efficiently obtain aggregate quantities in large-scale, dense wireless sensor networks (WSN) is based on the adaptation to wireless media of a MAC protocol, known as dominance/binary countdown, which existed previously only for wired media, and design algorithms that exploit this MAC protocol for efficient data aggregation. Designing and implementing such MAC protocol for wireless media is not trivial. For this reason, a substantial part of this work is focused on the development and implementation of WiDom (short for Wireless Dominance) - a wireless MAC protocol that enables efficient data aggregation in large-scale, dense WSN. An implementation of WiDom is first proposed under the assumption of a fully connected network (a network with a single broadcast domain). This implementation can be exploited to efficiently obtain aggregated quantities. WiDom can also implement static priority scheduling over wireless media. Therefore, a schedulability analysis for WiDom is also proposed. WiDom is then extended to operate in sensor networks where a single transmission cannot reach all nodes, in a network with multiple broadcast domains. These results are significant because often networks of nodes that take sensor readings are designed to be large scale, dense networks and it is exactly for such scenarios that the proposed distributed algorithms for obtaining aggregate quantities excel. The implementation and test of these distributed algorithms in a hardware platform developed shows that aggregate quantities in large-scale, dense wireless sensor systems can be obtained efficientlly.É possível prever um mundo onde estaremos rodeados por centenas ou até mesmo milhares de pequenos nós computacionais densamente instalados. Cada um destes nós será de dimensões muito reduzidas e possui capacidades para obter dados directamente do ambiente através de sensores e transmitir informação via rádio. Frequentemente, este tipo de redes são denominadas de redes de sensores sem fio. Perante tal cenário, o problema de lidar com a considerável quantidade de informação gerada por todos estes nós emerge como um desafio de grande relevância. A investigação apresentada nesta dissertação atenta neste desafio. Este trabalho de investigação prova que é possível obter quantidades agregadas com uma complexidade temporal que é independente do número de nós computacionais envolvidos, ou cresce muito lentamente quando o número de nós aumenta. Isto é conseguido através uma co-concepção dos algoritmos para obter quantidades agregadas e do sistema de comunicação subjacente. Este trabalho descreve (i) a concepção e implementação de um protocolo de acesso ao meio que garante prioridades estáticas em canais de comunicação sem fio e (ii) os algoritmos que permitem tirar partido deste protocolo de acesso ao meio para obter quantidades agregadas como o mínimo (MIN), máximo (MAX) e interpolação de valores obtidos a partir de sensores ambientais com uma complexidade que é independente do número de nós computacionais envolvidos. Estas técnicas também permitem obter, de forma eficiente, estimativas do número de nós (COUNT) e a mediana dos valores dos sensores (MEDIAN). A abordagem inovadora, proposta para obter de forma eficiente quantidades agregadas em redes de sensores sem fio de larga escala, é baseada na adaptação para meios de comunicação sem fio de um protocolo de acesso ao meio anteriormente apenas existente em sistemas cablados, e na concepção de algoritmos que tiram partido deste protocolo para agregação de dados eficiente. A concepção e implementação de tal protocolo de acesso ao meio não é trivial. Por esta razão, uma parte substancial deste trabalho é focada no desenvolvimento e implementação de um protocolo de acesso ao meio que permite agregação de dados eficiente em redes de sensores sem fio densas e de larga escala. Esta implementação é denominada de WiDom. A implementação do WiDom apresentada foi inicialmente desenvolvida assumindo que a rede é totalmente ligada (uma transmisão de um nó alcança todos os outros nós). Esta implementação pode ser explorada para obter quantidades agregadas de forma eficiente. Adicionalmente, o protocolo WiDom pode implementar escalonamento utilizando prioridades fixas, permitindo a proposta de uma análise de resposta temporal. Neste trabalho, o WiDom é também estendido para funcionar em redes onde a transmissão de um nó não pode alcançar todos os outros nós. Os resultados apresentados neste trabalho são relevantes porque as redes de sensores sem fio são frequentemente concebidas para serem densas e de larga escala. É exactamente nestes casos que os algoritmos propostos para obter quantidades agregadas de forma eficiente apresentam maiores vantagens. A implementação e teste destes algoritmos distribuídos numa plataforma especialmente desenvolvida para o efeito demonstra que de facto podem ser obtidas quandidades agregadas de forma eficiente, mesmo em redes de sensores sem fio densas e de larga escala.This research was partially developed at the Real-Time Computing System Research Centre (CISTER), from the School of Engineering of the Polytechnic of Porto (ISEP/IPP

East Asia Today

East Asia attracts growing interest in the West. Th e region is the world’s hotbed of economic growth, led by burgeoning China aided by more advanced Asian economies investing heavily in manufacturing and trading networks involving China. Western entrepreneurs clamor to join the China wave

MAMMALS IN PORTUGAL : A data set of terrestrial, volant, and marine mammal occurrences in P ortugal

Mammals are threatened worldwide, with 26% of all species being includedin the IUCN threatened categories. This overall pattern is primarily associatedwith habitat loss or degradation, and human persecution for terrestrial mam-mals, and pollution, open net fishing, climate change, and prey depletion formarine mammals. Mammals play a key role in maintaining ecosystems func-tionality and resilience, and therefore information on their distribution is cru-cial to delineate and support conservation actions. MAMMALS INPORTUGAL is a publicly available data set compiling unpublishedgeoreferenced occurrence records of 92 terrestrial, volant, and marine mam-mals in mainland Portugal and archipelagos of the Azores and Madeira thatincludes 105,026 data entries between 1873 and 2021 (72% of the data occur-ring in 2000 and 2021). The methods used to collect the data were: live obser-vations/captures (43%), sign surveys (35%), camera trapping (16%),bioacoustics surveys (4%) and radiotracking, and inquiries that represent lessthan 1% of the records. The data set includes 13 types of records: (1) burrowsjsoil moundsjtunnel, (2) capture, (3) colony, (4) dead animaljhairjskullsjjaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8),observation in shelters, (9) photo trappingjvideo, (10) predators dietjpelletsjpine cones/nuts, (11) scatjtrackjditch, (12) telemetry and (13) vocalizationjecholocation. The spatial uncertainty of most records ranges between 0 and100 m (76%). Rodentia (n=31,573) has the highest number of records followedby Chiroptera (n=18,857), Carnivora (n=18,594), Lagomorpha (n=17,496),Cetartiodactyla (n=11,568) and Eulipotyphla (n=7008). The data setincludes records of species classified by the IUCN as threatened(e.g.,Oryctolagus cuniculus[n=12,159],Monachus monachus[n=1,512],andLynx pardinus[n=197]). We believe that this data set may stimulate thepublication of other European countries data sets that would certainly contrib-ute to ecology and conservation-related research, and therefore assisting onthe development of more accurate and tailored conservation managementstrategies for each species. There are no copyright restrictions; please cite thisdata paper when the data are used in publications.info:eu-repo/semantics/publishedVersio

Mammals in Portugal: a data set of terrestrial, volant, and marine mammal occurrences in Portugal

Mammals are threatened worldwide, with ~26% of all species being included in the IUCN threatened categories. This overall pattern is primarily associated with habitat loss or degradation, and human persecution for terrestrial mammals, and pollution, open net fishing, climate change, and prey depletion for marine mammals. Mammals play a key role in maintaining ecosystems functionality and resilience, and therefore information on their distribution is crucial to delineate and support conservation actions. MAMMALS IN PORTUGAL is a publicly available data set compiling unpublished georeferenced occurrence records of 92 terrestrial, volant, and marine mammals in mainland Portugal and archipelagos of the Azores and Madeira that includes 105,026 data entries between 1873 and 2021 (72% of the data occurring in 2000 and 2021). The methods used to collect the data were: live observations/captures (43%), sign surveys (35%), camera trapping (16%), bioacoustics surveys (4%) and radiotracking, and inquiries that represent less than 1% of the records. The data set includes 13 types of records: (1) burrows | soil mounds | tunnel, (2) capture, (3) colony, (4) dead animal | hair | skulls | jaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8), observation in shelters, (9) photo trapping | video, (10) predators diet | pellets | pine cones/nuts, (11) scat | track | ditch, (12) telemetry and (13) vocalization | echolocation. The spatial uncertainty of most records ranges between 0 and 100 m (76%). Rodentia (n =31,573) has the highest number of records followed by Chiroptera (n = 18,857), Carnivora (n = 18,594), Lagomorpha (n = 17,496), Cetartiodactyla (n = 11,568) and Eulipotyphla (n = 7008). The data set includes records of species classified by the IUCN as threatened (e.g., Oryctolagus cuniculus [n = 12,159], Monachus monachus [n = 1,512], and Lynx pardinus [n = 197]). We believe that this data set may stimulate the publication of other European countries data sets that would certainly contribute to ecology and conservation-related research, and therefore assisting on the development of more accurate and tailored conservation management strategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publications

O inventário nacional do património geológico : abordagem metodológica e resultados = The national inventory of geological heritage : methodological approach and results

A existência de um inventário nacional de património geológico é fundamental para se poderem implementar estratégias de geoconservação. Este trabalho apresenta a metodologia usada no desenvolvimento do mais completo inventário de geossítios. realizado até ao momento em Portugal, assim como os principais resultados obtidos. O inventário vai integrar o Sistema de Informação do Património Natural e o Cadastro Nacional dos Valores Naturais Classificados, ambos geridos pelo Instituto de Conservação da Natureza e da Biodiversidade

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

A Hitchhiker's guide to functional magnetic resonance imaging

Functional Magnetic Resonance Imaging (fMRI) studies have become increasingly popular both with clinicians and researchers as they are capable of providing unique insights into brain functions. However, multiple technical considerations (ranging from specifics of paradigm design to imaging artifacts, complex protocol definition, and multitude of processing and methods of analysis, as well as intrinsic methodological limitations) must be considered and addressed in order to optimize fMRI analysis and to arrive at the most accurate and grounded interpretation of the data. In practice, the researcher/clinician must choose, from many available options, the most suitable software tool for each stage of the fMRI analysis pipeline. Herein we provide a straightforward guide designed to address, for each of the major stages, the techniques, and tools involved in the process. We have developed this guide both to help those new to the technique to overcome the most critical difficulties in its use, as well as to serve as a resource for the neuroimaging community.This article has been developed under the scope of the project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). We are also thankful to FCT-ANR/NEU-OSD/0258/2012 founded by FCT/MEC. RM and PSM are supported by FCT fellowship grants, from the Ph.D.-iHES program, with the references PDE/BDE/113604/2015 and PDE/BDE/113601/2015, respectively. PM is supported by a grant from the project “Better mental health during ageing based on temporal prediction of individual brain ageing trajectories (TEMPO)” (Contract grant number: P-139977) funded by Fundação Calouste Gulbenkian.info:eu-repo/semantics/publishedVersio