8,352 research outputs found

    Machine learning and mixed reality for smart aviation: applications and challenges

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    The aviation industry is a dynamic and ever-evolving sector. As technology advances and becomes more sophisticated, the aviation industry must keep up with the changing trends. While some airlines have made investments in machine learning and mixed reality technologies, the vast majority of regional airlines continue to rely on inefficient strategies and lack digital applications. This paper investigates the state-of-the-art applications that integrate machine learning and mixed reality into the aviation industry. Smart aerospace engineering design, manufacturing, testing, and services are being explored to increase operator productivity. Autonomous systems, self-service systems, and data visualization systems are being researched to enhance passenger experience. This paper investigate safety, environmental, technological, cost, security, capacity, and regulatory challenges of smart aviation, as well as potential solutions to ensure future quality, reliability, and efficiency

    Meta-ontology fault detection

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    Ontology engineering is the field, within knowledge representation, concerned with using logic-based formalisms to represent knowledge, typically moderately sized knowledge bases called ontologies. How to best develop, use and maintain these ontologies has produced relatively large bodies of both formal, theoretical and methodological research. One subfield of ontology engineering is ontology debugging, and is concerned with preventing, detecting and repairing errors (or more generally pitfalls, bad practices or faults) in ontologies. Due to the logical nature of ontologies and, in particular, entailment, these faults are often both hard to prevent and detect and have far reaching consequences. This makes ontology debugging one of the principal challenges to more widespread adoption of ontologies in applications. Moreover, another important subfield in ontology engineering is that of ontology alignment: combining multiple ontologies to produce more powerful results than the simple sum of the parts. Ontology alignment further increases the issues, difficulties and challenges of ontology debugging by introducing, propagating and exacerbating faults in ontologies. A relevant aspect of the field of ontology debugging is that, due to the challenges and difficulties, research within it is usually notably constrained in its scope, focusing on particular aspects of the problem or on the application to only certain subdomains or under specific methodologies. Similarly, the approaches are often ad hoc and only related to other approaches at a conceptual level. There are no well established and widely used formalisms, definitions or benchmarks that form a foundation of the field of ontology debugging. In this thesis, I tackle the problem of ontology debugging from a more abstract than usual point of view, looking at existing literature in the field and attempting to extract common ideas and specially focussing on formulating them in a common language and under a common approach. Meta-ontology fault detection is a framework for detecting faults in ontologies that utilizes semantic fault patterns to express schematic entailments that typically indicate faults in a systematic way. The formalism that I developed to represent these patterns is called existential second-order query logic (abbreviated as ESQ logic). I further reformulated a large proportion of the ideas present in some of the existing research pieces into this framework and as patterns in ESQ logic, providing a pattern catalogue. Most of the work during my PhD has been spent in designing and implementing an algorithm to effectively automatically detect arbitrary ESQ patterns in arbitrary ontologies. The result is what we call minimal commitment resolution for ESQ logic, an extension of first-order resolution, drawing on important ideas from higher-order unification and implementing a novel approach to unification problems using dependency graphs. I have proven important theoretical properties about this algorithm such as its soundness, its termination (in a certain sense and under certain conditions) and its fairness or completeness in the enumeration of infinite spaces of solutions. Moreover, I have produced an implementation of minimal commitment resolution for ESQ logic in Haskell that has passed all unit tests and produces non-trivial results on small examples. However, attempts to apply this algorithm to examples of a more realistic size have proven unsuccessful, with computation times that exceed our tolerance levels. In this thesis, I have provided both details of the challenges faced in this regard, as well as other successful forms of qualitative evaluation of the meta-ontology fault detection approach, and discussions about both what I believe are the main causes of the computational feasibility problems, ideas on how to overcome them, and also ideas on other directions of future work that could use the results in the thesis to contribute to the production of foundational formalisms, ideas and approaches to ontology debugging that can properly combine existing constrained research. It is unclear to me whether minimal commitment resolution for ESQ logic can, in its current shape, be implemented efficiently or not, but I believe that, at the very least, the theoretical and conceptual underpinnings that I have presented in this thesis will be useful to produce more foundational results in the field

    Copular clauses in Malay: synchronic, diachronic, and typological perspectives

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    This thesis examines the copulas ialah and adalah in Malay on different levels of linguistic analysis, in different periods in time, and against different genetically related languages. Addressing the scarcity of research on copular clauses in Malay in all three areas, namely synchrony, diachrony, and typology, this thesis aims to serve as a point of reference for future study on nonverbal predication in Malay and beyond. The synchronic portion of the thesis begins with a demonstration of the monomorphemic nature of the two copulas, which no longer exhibit the morphosyntax, semantics, and information structure of the morphemes that they appear to comprise, viz. 3rd person ia, existential verb ada, and focus marker lah. Following that, several syntactic and semantic phenomena, including extraction from copular clauses, copular inversion, and overt vs. zero encoding of the copula, are investigated. Lastly, the derivation of clefts in Malay is examined, which I reveal to be a type of copular construction despite the absence of an overt copula. I then show that the derivation of a cleft feeds the further derivation of a pseudocleft via remnant movement. In the history of Malay, ialah and adalah are shown to have emerged relatively recently, that is towards the end of the Classical Malay era, circa the 18th to 19th century. Ialah grammaticalised from the combination of 3rd person pronoun ia and comment marker lah in a topical construction that involved left dislocation. Specifically, the topic was reanalysed as the canonical subject, which subsequently forced the resumptive pronoun to undergo Spec-to-Head reanalysis, resulting in ialah grammaticalising into a copula heading TP. Meanwhile, adalah grammaticalised from semantically vacuous support auxiliary ada, also in combination with comment marker lah. Both copulas originally developed from the need to provide a host for the comment marker as a way of avoiding a violation of the stray affix filter.   The typological survey of copular clauses in Austronesian reveals that syntactic alignment and word order play a central role in the emergence of copulas in a language. Of the 40 languages examined, all the 19 languages that have overt copulas are accusatively aligned, except the ergatively aligned Formosan language Puyuma, which entails that ergative-absolutive and split ergative languages within Austronesian are statistically very unlikely to have overt copulas. In addition to that, 20 of the 25 accusatively aligned languages have SVO word order, whilst all of the 9 ergatively aligned languages have VSO word order. The word order of the language is relevant as all but two of the 19 languages with overt copulas have SVO word order. In consideration of these findings, I argue that the correlation among the three factors is such that change from ergative to accusative alignment triggers change in word order from verb-initial order to verb-medial order, and that this is conducive to the emergence of overt copulas. Furthermore, word order plays a crucial role in the emergence of overt copulas as they may develop in topical constructions following reanalysis of the left-dislocated topic as the canonical subject, as argued in the diachronic portion of the thesis. Given this path of development, I argue that pronominal copulas have not been able to develop in the ergatively aligned Philippine-type languages due to the lack of the notion of subject and the absence of the canonical subject position, which prevents reanalysis of left-dislocated topics as canonical subjects and subsequently resumptive pronouns as copulas, as undergone by the Malay copula ialah. In addition to that, verbal copulas cannot develop from posture verbs in the Philippine-type languages because of the clash between the unergative nature of posture verbs and the unaccusative nature of the copula, which presents a problem in the Philippine-type languages due to the encoding of the agent argument on the verb in the actor voice. Besides, the strict intransitive nature of the copular clause is incompatible with other voice alternations such as the benefactive and the locative, as the trigger in these voice alternations is encoded as an applied argument, making the clause transitive. Verbs of becoming also cannot copularise in the Philippine-type languages via semantic bleaching of the inchoative aspect, due to the robust morphological marking of aspect on the verb

    Modelling, Monitoring, Control and Optimization for Complex Industrial Processes

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    This reprint includes 22 research papers and an editorial, collected from the Special Issue "Modelling, Monitoring, Control and Optimization for Complex Industrial Processes", highlighting recent research advances and emerging research directions in complex industrial processes. This reprint aims to promote the research field and benefit the readers from both academic communities and industrial sectors

    ON EXPRESSIVENESS, INFERENCE, AND PARAMETER ESTIMATION OF DISCRETE SEQUENCE MODELS

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    Huge neural autoregressive sequence models have achieved impressive performance across different applications, such as NLP, reinforcement learning, and bioinformatics. However, some lingering problems (e.g., consistency and coherency of generated texts) continue to exist, regardless of the parameter count. In the first part of this thesis, we chart a taxonomy of the expressiveness of various sequence model families (Ch 3). In particular, we put forth complexity-theoretic proofs that string latent-variable sequence models are strictly more expressive than energy-based sequence models, which in turn are more expressive than autoregressive sequence models. Based on these findings, we introduce residual energy-based sequence models, a family of energy-based sequence models (Ch 4) whose sequence weights can be evaluated efficiently, and also perform competitively against autoregressive models. However, we show how unrestricted energy-based sequence models can suffer from uncomputability; and how such a problem is generally unfixable without knowledge of the true sequence distribution (Ch 5). In the second part of the thesis, we study practical sequence model families and algorithms based on theoretical findings in the first part of the thesis. We introduce neural particle smoothing (Ch 6), a family of approximate sampling methods that work with conditional latent variable models. We also introduce neural finite-state transducers (Ch 7), which extend weighted finite state transducers with the introduction of mark strings, allowing scoring transduction paths in a finite state transducer with a neural network. Finally, we propose neural regular expressions (Ch 8), a family of neural sequence models that are easy to engineer, allowing a user to design flexible weighted relations using Marked FSTs, and combine these weighted relations together with various operations

    Essays on risk attitudes, knowledge, extreme weather, and farmers' behaviors in rural Southeast Asia

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    Northeastern Thailand and Central Vietnam are two regions where pockets of poverty persist despite overall success in poverty reduction on the national level. While there are profound structural differences between Thailand and Vietnam, a common feature for both countries is that government policies promote the migration of rural labor to facilitate growth in the industrial and service sectors. Furthermore, policymakers in both countries have the vision to transform their agriculture towards large-scale farming, following the model of western agriculture. While out-migration from rural areas has taken place and the share in off- and non-farm income in total household income has been growing, the share of agriculture income in many cases is now less than 50 %. To date, labor rather than land (as in the past) is the main income-generating factor. However, agriculture still plays an essential role in the rural areas of these two countries. Farms are still small, and farm sizes almost remained the same over the past decades. Structural transformation of the rural areas as envisaged by policymakers does not take place. Households keep their agriculture as a backup and safety net and hence small-scale farming continues to dominate. At the same time, farmers in the two regions are increasingly exposed to severe weather events caused by climate change which makes them vulnerable to poverty and food insecurity (ADB, 2009; IPCC, 2014a; Blanc & Reilly, 2017). In this study, it is therefore aimed to obtain a better understanding of farmers' decision-making in agriculture. In particular, the thesis aims to investigate how farmer knowledge and skills and their risk attitudes, on the one hand, and the increasingly occurring extreme weather events, on the other hand, influence their decision-making with regard to farm management decisions. There are three specific research questions to be answered in this research: (1) how do risk attitudes affect household decision-making; (2) what is the impact of agricultural knowledge on agricultural production; (3) how do farmers manage their agricultural inputs in response to extreme weather events. To answer these questions, the thesis draws on two primary data sources. The first is the database of the Thailand Vietnam Socio Economic Panel (TVSEP) project during the period of 2007 to 2017, i.e., six-year panel dataset was collected from some 4,400 rural households in the Northeastern Thailand provinces of Nakhon Phanom, Ubon Ratchathani, and Buri Ram; and in Vietnam’s Central Coastal and Central Highlands provinces of Ha Tinh, Thua Thien Hue (Hue), and Dak Lak. The second data source is historical weather data. We use the monthly high-resolution (0.5) temperature and precipitation data observed from 1948 until 2016 from the Global Precipitation Climatology Centre (GPCC; Schneider et al., 2018), and the Global Historical Climatology Network Monthly - Version 2 and the Climate Anomaly Monitoring System (GHCN + CAMS; Fan & Dool, 2008), respectively. The results of the thesis are presented in three essays. The first essay is “Risk attitudes and implication for livelihoods strategy – evidence from two provinces in Thailand and Vietnam.” Utilizing an Ordinary Least Square (OLS) and a Probit regression with different alternative specifications, the determinants of risk preference for household decision-making are analyzed. Results show that risk attitudes are significantly related to individual characteristics such as age, gender, height, and household wealth. There are correlations between the willingness to take risk and real-life decisions of farm households. The findings show that risk-seeking individuals likely diversify income-generating activities as a cushion against the risk of small-scale farmers in these areas. They invest in self-employment and other non-farm enterprises while still capitalizing in agriculture. The second essay, named “Farmers’ knowledge and farm productivity in rural Thailand and Vietnam”, investigates the relationship between farmers’ knowledge, skills, and agricultural productivity. This paper uses primary data on agricultural knowledge and skill tests among “TVSEP households” in the provinces of Ubon Ratchathani in Thailand and Hue in Vietnam. A Two-Stage Least Squares (2SLS) approach combining knowledge and skills test results with productivity data of later waves was developed to identify the effects of agricultural knowledge and skills on agricultural productivity. The major finding is that technical knowledge in agriculture is significantly and positively associated with profit but significantly negative with rice yields and cost of input costs. This suggests that knowledgeable farmers may strive for optimal rather than maximum yield and are more judicious in the use of inputs which is good for the economy and the environment. In the third essay, named “Extreme weather and agricultural input management in rural Thailand and Vietnam: Intensify or de-intensify?” we investigate the impact of extreme weather events, namely drought, on household input management decisions in Northeastern Thailand and Central Vietnam. Eight inputs are captured: land, labor (household labor and hired labor), chemicals (i.e., fertilizer and pesticides), irrigation, machinery, and other agricultural investments. We define two binary drought indicators, namely severe drought and extreme drought, using the Standardized Precipitation Evapotranspiration Index (SPEI) as the criterion. We then use Fixed Effects (FE) model for this paper’s purpose. Results indicate that farmers tend to de-intensify agricultural production in terms of hired labor, pesticides, number of crops grown, and agricultural investments in response to severe droughts. Second, farmers increasingly hire machinery as a substitute for owned equipment and for household labor. Third, the magnitude of the effects increases with the severity of drought. Differentiating the analysis between countries, and upland versus lowland rice production, shows that the level of de-intensification varies. For example, Thai farmers allocate more family and hired labor to agricultural production; Vietnamese farmers invest in agricultural assets. Upland rice farmers focus on several inputs such as pesticides, machinery, and agricultural assets, while lowland farmers focus on available irrigation systems. All three essays have generated important policy messages for Governments in both countries to consider public support measures to strengthen rural households coping strategies toward extreme weather events and climate change

    Syntactic change during the anglicisation of Scots: insights from the Parsed Corpus of Scottish Correspondence

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    Variation and change in syntax is particularly challenging to measure quantitatively, as such investigation requires syntactically annotated (parsed) corpora; a parsed digital corpus allows for retrieval of all instances of a construction or particular word order in a fraction of the time it would take to retrieve the same information by hand. Compared to English, research on syntactic change in the history of Scots has been limited, in part due to the lack of such a resource. In order to meet these demands, this thesis presents the new Parsed Corpus of Scottish Correspondence (PCSC), consisting of 270,000 words of parsed data from the Helsinki Corpus of Scottish Correspondence 1540-1750 (Meurman-Solin and VARIENG 2017), and demonstrates the process in turning strings of words into searchable clause tokens by using a combination of automated and manual methods. The PCSC provides data from the 16th to 18th century, a previous blind spot within Scots syntax research despite being a highly interesting time period to investigate; these centuries saw a shift in the relationship between Scots and English, as English started to exert influence over Scots as a more socio-politically prestigious variety – consequently, salient Scots features were increasingly replaced by English ones in writing. Thus, the 16th-18th century marks a period of great change in Scots, as it went from being a more distinct variety on a standardisation trajectory, to the mixed variety we encounter in Scotland today. Using the new parsed data from the PCSC, I present results from three case studies on syntactic change in 16th to 18th century Scots, thus beginning to fill the gaps in our knowledge of this period. The findings of the case studies reveal the transformative nature of Scots syntax in the 16th to 18th century, as the language undergoes dramatic changes in its subject-verb agreement system through the decline of the Northern Subject Rule and the rise of do-support, and further rearrangement in the verbal paradigm through the rise of verbal -ing in both participial and gerundive function. On assessing whether these changes can be attributed to influence from English, or whether they are simply parallel developments in closely related language varieties, it is found that the nature of contact between Scots and English in the 16th-18th century, and the timing in which the changes take place, speaks in favour of these changes being contact-induced. However, further fine-grained investigation into the functions and distribution of the features involved, in Scots compared to English, will be needed before more firm conclusions can be drawn regarding the origin of the changes
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