Active Reading is an important part of a knowledge worker’s activities; it involves highlighting, writing notes, marking with symbols, etc., on a document. Many Active Reading applications have been designed in seeking to replicate the affordances of paper through digital-ink-based annotation tools. However, these applications require users to perform numerous steps to use various types of annotation tools, which impose an unnecessary cognitive load, distracting them from their reading tasks. In this thesis, we introduce GestAnnot, an Active Reading application for tablet computers that takes a fundamentally different approach of incorporating multi-touch gesture techniques for creating and manipulating annotations on an e-document, thus offering a flexible and easy- to-use annotation solution. Based on the literature review, we designed and developed GestAnnot and then performed lab and field evaluations of the software. In lab evaluation, GestAnnot performed better than one of the best existing annotation application in many aspects, including number of steps. The design was then refined based on the feedback received. The field evaluation of the improved design helped us to understand the performance of the application in the real world. We proposed a set of design guidelines through the feedback received from both evaluations, which any future Active Reading application could benefit from.

The thesis numerically explores the use and behavior of Active Hydraulic Devices (AHDs), creating a new capability to simulate and control a pipe system’s transient performance. Automatic control valves are the first type of AHDs studied in this research. Due to the challenges inherent in the design of a pressure relief valve (PRV), the general principles of PRV use and selection are studied along with the system’s response to the PRV parameters. A new application of PID (proportional, integral and derivative) control valve is envisioned that combines a remote sensor at the upstream end of a pipeline to create a non- or semi- reflective boundary at the downstream end. Case studies show that, with such a boundary, the reflection and resonance of pressure waves within the pipeline are sometimes eliminated and invariably limited. The second type of AHDs studied in this research is the governed hydro turbine, the most complicated hydraulic component in terms of transient analysis and waterhammer control. A complete numerical model is developed for the turbine installations in either urban water networks or conventional hydropower generation systems. Using the model, transient simulations for several realistic hydro projects are presented along with various transient control measures.

Skirtinguose ventiliuojamo sampilo sluoksniuose vyksta skirtingi procesai: vėsimo ir šilimo, džiūvimo ir drėkimo, skiriasi grūdų ir grūdų sampilo fizikinės savybės: sampilo aukščio ir grūdų tūrio pokytis, birumas ir paviršiaus šiurkštumas, aerodinaminės ir kitos savybės. Vykstančius procesus įtakoja daug veiksnių, iš kurių vienas svarbiausių yra ventiliavimo intensyvumas. Storame nejudančiame sampile skirtingo intensyvumo oro srautais ventiliuojamų grūdų džiūvimo procesų pažinimas leistų išplėsti džiovinimo aktyviąja ventiliacija galimybes išsaugant jos privalumus ir nepakenkiant džiovinamos produkcijos kokybei. Tyrimų tikslas – ištirti oro srauto (ventiliavimo intensyvumo) įtaką aktyviąja ventiliacija džiovinamų grūdų džiūvimo ir jo sampilo savybių – aukščio, kitimo procesus. Grūdų džiovinimo storame nejudančiame sluoksnyje tyrimams atlikti buvo naudojamas stendas. Tyrimo metu grūdai džiovinti 23 ± 1,5 °C temperatūros pašildytu aplinkos oru, pučiant 320, 450, 650, 750 ir 900 lyginamąjį oro srautą. Tuo pačiu tyrimų metu buvo fiksuojamas sampilo aukščio pokytis, temperatūra, santykinis drėgnis. Tyrimų metu buvo nustatyta, kad didžiausias aktyviąja ventiliacija džiovinamų grūdų sampilo nusėdimas (18±1,2 %) įvyksta ventiliuojant didesniu nei lyginamuoju oro srautu. / Different layers of ventilated store involve different processes: cooling and warming, drying and moistening, grain and grain store physical characteristics such as change in height and volume, friability and surface roughness, aerodynamic and other characteristics differ. The processes are influenced by many factors; one of the most important is the intensity of the ventilation. Awareness of grain drying processes in the thick and stable store where ventilation is of different intensity air flow might expand drying possibilities by active ventilation saving efficiency and quality of the production. The purpose of the research is to examine the influence of airflow (ventilation intensity) on drying grain and the store characteristics – height and changing processes when drying by active ventilation. The stand was used in order to carry out the research in thick and stable layer. During the research grain was dried in warmed environment at the temperature of 23 ± 1.5 °C blowing 320, 450, 650, 750 and 900 relative airflow. The change of the store height, temperature, relative humidity was fixed during the research. It was found out that the greatest subsidence (18±1.2 %) of drying grain by active ventilation is when relative airflow is more than .

Recent research has lead to the possible discovery of a new class of gamma-ray emitting ac- tive galactic nuclei (AGN). These objects – the very radio-loud narrow-line Seyfert 1 galaxies (NLSy1s)– demonstrate observational features suggesting that they are similar to blazars. One of the key characteristics of blazars is the presence of high-amplitude optical microvariability. While this phenomenon has been investigated in individual objects, no study of the intra-night variability of radio-loud NLSy1s as a class has previously been available. This dissertation presents a sys- tematic search for optical variability in a sample of 33 radio-loud NLSy1s. It was found that 26 objects demonstrated microvariations. However, only 9 objects did so with duty cycles comparable to blazars, and only 7 of these 9 objects — J0706+3901, J0849+5108, J0948+0022, J1246+0238, PKS 1502+036, J1644+2619, and IRAS 20181-2244 — demonstrated microvariability at compa- rable amplitudes. Two objects stand out as exceptional sources. J0849+5108 was found to have a duty cycle of ~90% and was observed to undergo an enormous 4-magnitude optical flare in a two-month time span. The object has not been reported to have undergone such an event since 1975. The second object, J0948+0022, is the class prototype. High cadence data indicates that J0948+0022 has a remarkably rapid doubling time scale of ~40 minutes, and it was seen to vary by over 0.9 magnitudes within an individual night. Attempts to correlate microvariability to radio loudness, gamma-ray loudness, and other parameters were largely unsuccessful. However, it was found that only radio-loud NLSy1s that were detected at gamma-ray energies demonstrated microvariability at blazar-like duty cycles. Additionally, an analysis of the frequency of microvariations at various amplitudes suggests that the sample of radio-loud NLSy1s presented in this study share a parent population identical to low energy peaked BL Lac-type (LBL) blazars. This is in agreement with the work of astronomers such as Abdo et al. 2009, who have created spectral energy distributions for a few radio-loud NLSy1s and found them to resemble those of LBLs. Blazar-like variability was found in multiple objects with radio loudnesses of log(R) < 2, suggesting that even moderately radio-loud NLSy1s may be blazar-like objects.

Voltage control in distribution networks is becoming more challenging due to the growing amount of distributed generation that is being connected to the distribution networks in addition to increasing load. The output of the distributed generation can radically change power flows and voltage profiles in distribution networks, creating conditions that adversely affect the performance of automatic voltage control schemes and in addition cause unacceptable voltage rise. On the other hand, inherent limitations and current operational policies of AVC schemes very often restrict the output of DG or even prevent its connection. This thesis investigates and analyses voltage control in terms of the shift from passive to active distribution networks. The thesis also reviews the performance of AVC schemes under varying load and generation output conditions, investigates effective utilisation of distribution network assets and methods to accommodate active voltage control schemes into existing infrastructure. A range of active voltage control and management schemes based on coordinated voltage control is presented and assessed. These schemes can be used to improve the voltage profile in distribution networks and increase their ability to accommodate distributed generation. The functionality of each scheme is assessed based on a number of factors such as the ability of the scheme to increase network capacity, reliability and accuracy. Simulation software to accurately evaluate the performance of an active voltage control scheme in a particular distribution network scenario is essential before the scheme can be deployed. Formal assessment of advanced AVC models and SuperTAPP n+ functionality is performed using simulation software as developed and presented in this thesis. The accuracy of the software results and performance of the SuperTAPP n+ scheme is validated based on network trials carried out in EDF Energy Networks.

In this thesis I study the inner-most regions of Active Galactic Nuclei (AGN) using the reverberation mapping technique, and neutron star low-mass X-ray binaries in quiescence using X-ray observations. Using the 13-year optical monitoring data for the AGN NGC 5548, the luminosity dependence of the Hβ emitting radius was modelled using a delay map, finding that the radius scales with luminosity as predicted by recent theoretical models. Time-delays between the continuum at different wavelengths in AGN can be used to probe the accretion disc. Here, continuum time-delays in a sample of 14 AGN were used to measure the radial temperature profile of the accretion discs, determine the nuclear extinction, and measure distances to the objects. However, the distances measured correspond to a value for Hubble's constant that is a factor of ~2 lower than the accepted value. The implications of this on the thermal disc reprocessing model are discussed. I present two Chandra observations of the neutron star transient in the globular cluster NGC 6440 in quiescence, where the power-law component to the spectrum is seen to be variable between the observations, suggesting that there is ongoing residual accretion. From a Chandra observation of the globular cluster Terzan 1, I have identifed the likely quiescent counterpart to a transient previously observed in outburst, and discuss the other sources within the cluster. Using Chandra and XMM-Newton monitoring observations of two neutron star transients (KS 1731-260 and MXB 1659-29) in quiescence I have found that the neutron star crusts in both sources have now returned to thermal equilibrium with the core. These observations also indicate that the crusts in both sources may have a high thermal conductivity and that enhanced neutrino emission may be occurring in the core. Finally, the discovery of an X-ray transient with XMM-Newton is presented, and the other sources in this observation discussed.

Data generation has vastly exceeded manual annotation in several areas of astronomy, biology, economy, geology, medicine and physics. At the same time, a public community of experts and hobbyists has developed around some of these disciplines thanks to open, editable web resources such as wikis and public annotation challenges. In this thesis I investigate under which conditions a combination of collaborative and automated curation could complete annotation tasks unattainable by human curators alone. My exemplar curation process is taken from the molecular biology domain: the association all existing enzymes (proteins catalysing a chemical reaction) with their function. Assigning enzymatic function to the proteins in a genome is the first essential problem of metabolic reconstruction, important for biology, medicine, industrial production and environmental studies. In the protein database UniProt, only 3% of the records are currently manually curated and only 60% of the 17 million recorded proteins have some functional annotation, including enzymatic annotation. The proteins in UniProt represent only about 380,000 animal species (2,000 of which have completely sequenced genomes) out of the estimated millions of species existing on earth. The enzyme annotation task already applies to millions of entries and this number is bound to increase rapidly as sequencing efforts intensify. To guide my analysis I first develop a basic model of collaborative curation and evaluate it against molecular biology knowledge bases. The analysis highlights a surprising similarity between open and closed annotation environments on metrics usually connected with “democracy” of content. I then develop and evaluate a method to enhance enzyme function annotation using machine learning which demonstrates very high accuracy, recall and precision and the capacity to scale to millions of enzyme instances. This method needs only a protein sequence as input and is thus widely applicable to genomic and metagenomic analysis. The last phase of the work uses active and guided learning to bring together collaborative and automatic curation. In active learning a machine learning algorithm suggests to the human curators which entry should be annotated next. This strategy has the potential to coordinate and reduce the amount of manual curation while improving classification performance and reducing the number of training instances needed. This work demonstrates the benefits of combining classic machine learning and guided learning to improve the quantity and quality of enzymatic knowledge and to bring us closer to the goal of annotating all existing enzymes.

Humans must regularly locate task-relevant objects when interacting with the world around them. Previous research has identified different types of information that the visual system can use to help locate objects in real-world scenes, including low-level image features and scene context. However, previous research using object arrays suggest that there may be another type of information that can guide real-world search: target knowledge. When a participant knows what a target looks like they generate and store a visual representation, or template, of it. This template then facilitates the search process. A complete understanding of real-world search needs to identify how a target template guides search through scenes. Three experiments in Chapter 2 confirmed that a target template facilitates realworld search. By using an eye-tracker target knowledge was found to facilitate both scanning and verification behaviours during search, but not the search initiation process. Within the scanning epoch a target template facilitated gaze directing and shortened fixation durations. These results suggest that target knowledge affects both the activation map, which selects which regions of the scene to fixate, and the evaluation process that compares a fixated object to the internal representation of the target. With the exact behaviours that a target template facilitates now identified, Chapter 3 investigated the role that target colour played in template-guided search. Colour is one of the more interesting target features as it has been shown to be preferred by the visual system over other features when guiding search through object arrays. Two real-world search experiments in Chapter 3 found that colour information had its strongest effect on the gaze directing process, suggesting that the visual system relies heavily on colour information when searching for target-similar regions in the scene percept. Although colour was found to facilitate the evaluation process too, both when rejecting a fixated object as a distracter and accepting it as the target, this behaviour was found to be influenced comparatively less. This suggests that the two main search behaviours – gaze directing and region evaluation – rely on different sets of template features. The gaze directing process relies heavily on colour information, but knowledge of other target features will further facilitate the evaluation process. Chapter 4 investigated how target knowledge combined with other types of information to guide search. This is particularly relevant in real-world search where several sources of guidance information are simultaneously available. A single experiment investigated how target knowledge and scene context combined to facilitate search. Both information types were found to facilitate scanning and verification behaviours. During the scanning epoch both facilitated the eye guidance and object evaluation processes. When both information sources were available to the visual system simultaneously, each search behaviour was facilitated additively. This suggests that the visual system processes target template and scene context information independently. Collectively, the results indicate not only the manner in which a target template facilitates real-world search but also updates our understanding of real-world search and the visual system. These results can help increase the accuracy of future realworld search models by specifying the manner in which our visual system utilises target template information, which target features are predominantly relied upon and how target knowledge combines with other types of guidance information.

There has been growing recent interest in the field of active learning for binary classification. This thesis develops a Bayesian approach to active learning which aims to minimise the objective function on which the learner is evaluated, namely the expected misclassification cost. We call this approach the expected cost reduction approach to active learning. In this form of active learning queries are selected by performing a `lookahead' to evaluate the associated expected misclassification cost. \paragraph{} Firstly, we introduce the concept of a \textit{query density} to explicitly model how new data is sampled. An expected cost reduction framework for active learning is then developed which allows the learner to sample data according to arbitrary query densities. The model makes no assumption of independence between queries, instead updating model parameters on the basis of both which observations were made \textsl{and} how they were sampled. This approach is demonstrated on the probabilistic high-low game which is a non-separable extension of the high-low game presented by \cite{Seung_etal1993}. The results indicate that the Bayes expected cost reduction approach performs significantly better than passive learning even when there is considerable overlap between the class distributions, covering $30\%$ of input space. For the probabilistic high-low game however narrow queries appear to consistently outperform wide queries. We therefore conclude the first part of the thesis by investigating whether or not this is always the case, demonstrating examples where sampling broadly is favourable to a single input query. \paragraph{} Secondly, we explore the Bayesian expected cost reduction approach to active learning within the pool-based setting. This is where learning is limited to a finite pool of unlabelled observations from which the learner may select observations to be queried for class-labels. Our implementation of this approach uses Gaussian process classification with the expectation propagation approximation to make the necessary inferences. The implementation is demonstrated on six benchmark data sets and again demonstrates superior performance to passive learning.

Conventional passive metamaterials always suffer from the limitation of loss and dispersion due to fundamental causality issue. Especially it becomes severe due to material loss at terahertz frequency. Our work resolves the loss problem by introducing gain device into the metamaterial structure. A passive volumetric metamaterial is firstly designed on the quartz substrate. A negative resistance is inserted into the wire of the structure to provide the gain. We have identified resonant tunneling diodes that work up into THz frequency and shown in simulation that simultaneous negative index and gain can be obtained.