Adaptive edge analytics for distributed networked control of water systems

Over the last decade, there has been a trend where water utility companies aim to make water distribution networks more intelligent in order to improve their quality of service, reduce water waste, minimize maintenance costs etc., by incorporating IoT technologies. Current state of the art solutions use expensive power hungry deployments to monitor and transmit water network states periodically in order to detect anomalous behaviors such as water leakage and bursts. However, more than 97% of water network assets are remote away from power and are often in geographically remote underpopulated areas, facts that make current approaches unsuitable for next generation more dynamic adaptive water networks. Battery-driven wireless sensor/actuator based solutions are theoretically the perfect choice to support next generation water distribution. In this paper, we present an end-to-end water leak localization system, which exploits edge processing and enables the use of battery-driven sensor nodes. Our system combines a lightweight edge anomaly detection algorithm based on compression rates and an efficient localization algorithm based on graph theory. The edge anomaly detection and localization elements of the systems produce a timely and accurate localization result and reduce the communication by 99% compared to the traditional periodic communication. We evaluated our schemes by deploying non-intrusive sensors measuring vibrational data on a real-world water test rig that have had controlled leakage and burst scenarios implemented.

On the Bleeding Edge : Debloating Internet Access Networks

As ever more devices are connected to the internet, and applications turn ever more interactive, it becomes more important that the network can be counted on to respond reliably and without unnecessary delay. However, this is far from always the case today, as there can be many potential sources of unnecessary delay. In this thesis we focus on one of them: Excess queueing delay in network routers along the path, also known as bufferbloat. We focus on the home network, and treat the issue in three stages. We examine latency variation and queueing delay on the public internet and show that significant excess delay is often present. Then, we evaluate several modern AQM algorithms and packet schedulers in a residential setting, and show that modern AQMs can almost entirely eliminate bufferbloat and extra queueing latency for wired connections, but that they are not as effective for WiFi links. Finally, we go on to design and implement a solution for bufferbloat at the WiFi link, and also design a workable scheduler-based solution for realising airtime fairness in WiFi. Also included in this thesis is a description of Flent, a measurement tool used to perform most of the experiments in the other papers, and also used widely in the bufferbloat community.

Edge enhancement improves disruptive camouflage by emphasising false edges and creating pictorial relief

Disruptive colouration is a visual camouflage composed of false edges and boundaries. Many disruptively camouflaged animals feature enhanced edges; light patches are surrounded by a lighter outline and/or a dark patches are surrounded by a darker outline. This camouflage is particularly common in amphibians, reptiles and lepidopterans. We explored the role that this pattern has in creating effective camouflage. In a visual search task utilising an ultra-large display area mimicking search tasks that might be found in nature, edge enhanced disruptive camouflage increases crypsis, even on substrates that do not provide an obvious visual match. Specifically, edge enhanced camouflage is effective on backgrounds both with and without shadows; i.e. this is not solely due to background matching of the dark edge enhancement element with the shadows. Furthermore, when the dark component of the edge enhancement is omitted the camouflage still provided better crypsis than control patterns without edge enhancement. This kind of edge enhancement improved camouflage on all background types. Lastly, we show that edge enhancement can create a perception of multiple surfaces. We conclude that edge enhancement increases the effectiveness of disruptive camouflage through mechanisms that may include the improved disruption of the object outline by implying pictorial relief.

Living on the edge : Social exclusion and the receipt of informal care in older people

Older people have been identified as being at risk of social exclusion. However, despite the fact that care is commonly required in later life and the majority of that care provided by informal carers, a connection between social exclusion and informal care-receipt has rarely been considered. The aim of this study was to examine how informal care-receipt is related to social exclusion. A face-to-face questionnaire survey on social exclusion and informal care-receipt was carried out among older people (n=1255) living in Barnsley, United Kingdom. Multivariable analyses examined the association between social exclusion and categories of informal care-receipt: care receiver; assurance receiver; non-receiver with no need; non-receiver with need. Compared to being a non-receiver with no need participants were more likely to be a care receiver or assurance receiver if they had higher levels of social exclusion. The highest level of social exclusion, however, was found in non-receivers with need. Despite a lack of informal care and support, formal practical support and personal care was also low in this latter group. Findings are discussed in relation to the conceptualisation of care-receipt and how contact with medical services could be an opportunity for identification and appropriate referral of non-receivers with need.

The use of traits to interpret responses to large scale - edge effects: a study of epigaeic beetle assemblages across a Eucalyptus forest and pine plantation edge

Context: Edge effects due to habitat loss and fragmentation have pervasive impacts on many natural ecosystems worldwide. Objective: We aimed to explore whether, in tandem with the resource-based model of edge effects, species feeding-guild and flight-capacity can help explain species responses to an edge. Methods: We used a two-sided edge gradient that extended from 1000 m into native Eucalyptus forest to 316 m into an exotic pine plantation. We used generalised additive models to examine the continuous responses of beetle species, feeding-guild species richness and flight-capable group species richness to the edge gradient and environmental covariates. Results: Phytophagous species richness was directly related to variation in vegetation along the edge gradient. There were more flight-capable species in Eucalyptus forest and more flightless species in exotic pine plantation. Many individual species exhibited multiple-peaked edge-profiles. Conclusions: The resource based model for edge effects can be used in tandem with traits such as feeding-guild and flight-capacity to understand drivers of large scale edge responses. Some trait-groups can show generalisable responses that can be linked with drivers such as vegetation richness and habitat structure. Many trait-group responses, however, are less generalisable and not explained by easily measured habitat variables. Difficulties in linking traits with resources along the edge could be due to unmeasured variation and indirect effects. Some species’ responses reached the limits of the edge gradient demonstrating the need to examine edge effects at large scales, such as kilometres.

Genetic structure and sex-biased dispersal of a declining cooperative-breeder, the Grey-crowned Babbler, Pomatostomus temporalis, at the southern edge of its range

Loss and fragmentation of habitat can disrupt genetic exchange between populations, which is reflected in changes to the genetic structure of populations. The Grey-crowned Babbler (Pomatostomus temporalis) is a cooperatively breeding woodland bird, once common and widespread in south-eastern Australia. The species has suffered population declines of >90% across its southern distribution as a result of loss and fragmentation of habitat. We investigated patterns of genetic diversity and population structure of Grey-crowned Babblers in fragmented habitats at the southernmost extent of its range. We sampled blood from 135 individual Babblers from 39 groups stratified into six subpopulations in three regions. Genotypic data were used to estimate genetic diversity, population substructure, local relatedness and dispersal patterns. Individuals showed high heterozygosity within regions, and varying numbers of private alleles among regions suggested differences in levels of connectivity between regions. Four genetic clusters revealed population substructure consistent with treeless landscapes acting as strong barriers to gene flow. In contrast to previous studies,we identified a male-biased dispersal pattern and significant isolation-by-distance patterns for females at fine spatial scales. We recommend that conservation plans for this species incorporate opportunities to increase and enhance corridor areas to facilitate genetic exchange among subpopulations.

Living on the intertidal/subtidal edge: ecology of the stalked barnacle Pollicipes Pollicipes and of the sea urchin Paracentrotus lividus

This thesis contributes to the knowledge of temperate rocky shore ecology, with direct implications in the management and conservation of two important local marine resources that inhabit the very edge of subtidal and intertidal habitats on wave-swept rocky shores: the sessile filter feeding stalked barnacle Pollicipes pollicipes and the mobile keystone herbivore sea urchin Paracentrotus lividus. Research was conducted along gradients of wave exposure on rocky shores of Southern Europe. The abundance of P. lividus was four times higher in SW Portugal than in NW Italy. Most of the variation in urchin abundance occurred at small spatial scales, probably shaped by habitat complexity. In SW Portugal, sea urchin attachment forces while in burrows were measured and related to burrow shape, urchin size and habitat. Burrowing behaviour enhances sea urchin attachment force and might be an adaptive response to hydrodynamic stress. Abundance of P. pollicipes in SW Portugal is highly and positively related to wave exposure at local and regional scales. Predation and recruitment processes seem to be important drivers of these abundance patterns. A distribution model of P. pollicipes abundance in relation to wave exposure was developed for the SW coast of Portugal and might be used for improvement of its management and conservation. Growth of P. pollicipes was studied by applying a novel method using fluorescent calcein for marking and to estimate growth. Growth rate decreased with barnacle size and was highly variable amongst individuals, particularly in smaller barnacles. No effect of shore level on barnacle growth was detected. An assessment of the state of the fishery, conservation and management of the stalked barnacle in different regions of continental Portugal was made, highlighting an overall negative tendency of this state and recommending a change into a co-management system; Resumo: Viver no limite intertidal / subtidal: ecologia do percebe Pollicipes pollicipes e do ouriço-do-mar Paracentrotus lividus Esta tese contribui para o conhecimento da ecologia do litoral rochoso e tem implicações diretas na gestão e conservação de dois recursos marinhos locais que habitam o interface subtidal/intertidal de costas rochosas sujeitas a agitação marinha: o percebe Pollicipes pollicipes, animal séssil e filtrador e o ouriço-do-mar Paracentrotus lividus, animal móvel e herbívoro. Foram realizados vários estudos ao longo de gradientes de hidrodinamismo em costas rochosas do sul da Europa. A abundância de P. lividus foi quatro vezes superior no sudoeste de Portugal relativamente ao noroeste de Itália. Grande parte da variação na abundância de P. lividus ocorreu a pequenas escalas espaciais, provavelmente influenciada pela complexidade do habitat. A força com que o ouriço-do-mar se fixa ao substrato foi medida no terreno no sudoeste de Portugal, tendo esta sido relacionada com a forma da depressão que ocupa, o tamanho individual e o habitat. O comportamento escavador desta espécie aumenta a sua força de fixação ao substrato e poderá ser uma resposta adaptativa ao hidrodinamismo.. A abundância de P. pollicipes na costa sudoeste de Portugal, a diferentes escalas espaciais, está relacionada de forma positiva com a agitação marinha, e é influenciada pela predação e pelo recrutamento desta espécie. Foi desenvolvido um modelo de distribuição e abundância de P. pollicipes para esta costa baseado na relação com a agitação marinha, cujos resultados podem ser usados para melhorar a gestão e conservação deste recurso. Um novo método com recurso a calceina fluorescente foi desenvolvido para marcar percebes e estudar o seu crescimento. A taxa de crescimento diminuiu com o tamanho do animal, sendo altamente variável entre indivíduos, sobretudos nos de menores dimensões. O estado da apanha, conservação e gestão do percebe em diferentes regiões de Portugal Continental apresentou uma tendência global negativa, e recomenda-se uma alteração para um sistema de cogestão deste recurso.

Tuning the valence of the cerium center in (Na)phthalocyaninato and porphyrinato cerium double-deckers by changing the nature of the tetrapyrrole ligands

A series of 7 cerium double-decker complexes with various tetrapyrrole ligands including porphyrinates, phthalocyaninates, and 2,3-naphthalocyaninates have been prepared by previously described methodologies and characterized with elemental analysis and a range of spectroscopic methods. The molecular structures of two heteroleptic \[(na)phthalocyaninato](porphyrinato) complexes have also been determined by X-ray diffraction analysis which exhibit a slightly distorted square antiprismatic geometry with two domed ligands. Having a range of tetrapyrrole ligands with very different electronic properties, these compounds have been systematically investigated for the effects of ligands on the valence of the cerium center. On the basis of the spectroscopic (UV−vis, near-IR, IR, and Raman), electrochemical, and structural data of these compounds and compared with those of the other rare earth(III) counterparts reported earlier, it has been found that the cerium center adopts an intermediate valence in these complexes. It assumes a virtually trivalent state in cerium bis(tetra-tert-butylnaphthalocyaninate) as a result of the two electron rich naphthalocyaninato ligands, which facilitate the delocalization of electron from the ligands to the metal center. For the rest of the cerium double-deckers, the cerium center is predominantly tetravalent. The valences (3.59−3.68) have been quantified according to their LIII-edge X-ray absorption near-edge structure (XANES) profiles.

Tracking people in 3D using position, size and shape

This paper presents a prototype tracking system for tracking people in enclosed indoor environments where there is a high rate of occlusions. The system uses a stereo camera for acquisition, and is capable of disambiguating occlusions using a combination of depth map analysis, a two step ellipse fitting people detection process, the use of motion models and Kalman filters and a novel fit metric, based on computationally simple object statistics. Testing shows that our fit metric outperforms commonly used position based metrics and histogram based metrics, resulting in more accurate tracking of people.

Components of learning and assessment in linear algebra

Linear algebra provides theory and technology that are the cornerstones of a range of cutting edge mathematical applications, from designing computer games to complex industrial problems, as well as more traditional applications in statistics and mathematical modelling. Once past introductions to matrices and vectors, the challenges of balancing theory, applications and computational work across mathematical and statistical topics and problems are considerable, particularly given the diversity of abilities and interests in typical cohorts. This paper considers two such cohorts in a second level linear algebra course in different years. The course objectives and materials were almost the same, but some changes were made in the assessment package. In addition to considering effects of these changes, the links with achievement in first year courses are analysed, together with achievement in a following computational mathematics course. Some results that may initially appear surprising provide insight into the components of student learning in linear algebra.

Sound radiation characteristics of a box-type structure

The finite element and boundary element methods are employed in this study to investigate the sound radiation characteristics of a box-type structure. It has been shown [T.R. Lin, J. Pan, Vibration characteristics of a box-type structure, Journal of Vibration and Acoustics, Transactions of ASME 131 (2009) 031004-1–031004-9] that modes of natural vibration of a box-type structure can be classified into six groups according to the symmetry properties of the three panel pairs forming the box. In this paper, we demonstrate that such properties also reveal information about sound radiation effectiveness of each group of modes. The changes of radiation efficiencies and directivity patterns with the wavenumber ratio (the ratio between the acoustic and the plate bending wavenumbers) are examined for typical modes from each group. Similar characteristics of modal radiation efficiencies between a box structure and a corresponding simply supported panel are observed. The change of sound radiation patterns as a function of the wavenumber ratio is also illustrated. It is found that the sound radiation directivity of each box mode can be correlated to that of elementary sound sources (monopole, dipole, etc.) at frequencies well below the critical frequency of the plates of the box. The sound radiation pattern on the box surface also closely related to the vibration amplitude distribution of the box structure at frequencies above the critical frequency. In the medium frequency range, the radiated sound field is dominated by the edge vibration pattern of the box. The radiation efficiency of all box modes reaches a peak at frequencies above the critical frequency, and gradually approaches unity at higher frequencies.