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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reference object choice in spatial language : machine and human models

Barclay, Michael John January 2010 (has links)
The thesis underpinning this study is as follows; it is possible to build machine models that are indistinguishable from the mental models used by humans to generate language to describe their environment. This is to say that the machine model should perform in such a way that a human listener could not discern whether a description of a scene was generated by a human or by the machine model. Many linguistic processes are used to generate even simple scene descriptions and developing machine models of all of them is beyond the scope of this study. The goal of this study is, therefore, to model a sufficient part of the scene description process, operating in a sufficiently realistic environment, so that the likelihood of being able to build machine models of the remaining processes, operating in the real world, can be established. The relatively under-researched process of reference object selection is chosen as the focus of this study. A reference object is, for instance, the `table' in the phrase ``The flowers are on the table''. This study demonstrates that the reference selection process is of similar complexity to others involved in generating scene descriptions which include: assigning prepositions, selecting reference frames and disambiguating objects (usually termed `generating referring expressions'). The secondary thesis of this study is therefore; it is possible to build a machine model that is indistinguishable from the mental models used by humans in selecting reference objects. Most of the practical work in the study is aimed at establishing this. An environment sufficiently near to the real-world for the machine models to operate on is developed as part of this study. It consists of a series of 3-dimensional scenes containing multiple objects that are recognisable to humans and `readable' by the machine models. The rationale for this approach is discussed. The performance of human subjects in describing this environment is evaluated, and measures by which the human performance can be compared to the performance of the machine models are discussed. The machine models used in the study are variants on Bayesian networks. A new approach to learning the structure of a subset of Bayesian networks is presented. Simple existing Bayesian classifiers such as naive or tree augmented naive networks did not perform sufficiently well. A significant result of this study is that useful machine models for reference object choice are of such complexity that a machine learning approach is required. Earlier proposals based on sum-of weighted-factors or similar constructions will not produce satisfactory models. Two differently derived sets of variables are used and compared in this study. Firstly variables derived from the basic geometry of the scene and the properties of objects are used. Models built from these variables match the choice of reference of a group of humans some 73\% of the time, as compared with 90\% for the median human subject. Secondly variables derived from `ray casting' the scene are used. Ray cast variables performed much worse than anticipated, suggesting that humans use object knowledge as well as immediate perception in the reference choice task. Models combining geometric and ray-cast variables match the choice of reference of the group of humans some 76\% of the time. Although niether of these machine models are likely to be indistinguishable from a human, the reference choices are rarely, if ever, entirely ridiculous. A secondary goal of the study is to contribute to the understanding of the process by which humans select reference objects. Several statistically significant results concerning the necessary complexity of the human models and the nature of the variables within them are established. Problems that remain with both the representation of the near-real-world environment and the Bayesian models and variables used within them are detailed. While these problems cast some doubt on the results it is argued that solving these problems is possible and would, on balance, lead to improved performance of the machine models. This further supports the assertion that machine models producing reference choices indistinguishable from those of humans are possible.
2

Från totalförsvar till gemensam säkerhet : en studie av vidgade säkerhetsperspektiv / From Total Defence to Common Security : a study of broader security perspectives

Lundqvist, Stefan January 2009 (has links)
<p>Den säkerhetspolitiska debatten har under de senaste åren tillvaratagit ett bredare perspektiv av hot och risker. Undersökningen tar sin utgångspunkt i frågan om i vilken utsträckning detta kommit till uttryck i svenska försvarspropositioner?</p><p> </p><p>Undersökningen kartlägger likheter och skillnader i tre försvarspropositioners uttryck av hot och säkerhet relaterat till det vidgade säkerhetsbegreppet under perioden 1982-2009. Vid kartläggningen undersöker jag med hjälp av Barry Buzan m.fl. analysramverk för det vidgade säkerhetsbegreppet vilka säkerhetspolitiska värden som uttrycktes vara viktiga att säkerställa. Undersökningen kartlägger även hotbilderna som uppfattades mot dessa värden och inom vilka arenor deras säkerhet bedömdes kunna säkerställas.</p><p>Analysen påvisar olikheter i de tre försvarspropositionernas säkerhetspolitiska uttryck. 1982 års försvarsproposition fokuserar på nationella säkerhetspolitiska värden som säkerställdes inom totalförsvarets ram. De följande försvarspropositionerna indikerar en förändring till förmån för regionala värden och gemensam säkerhet. Analysen påvisar även en radikal förändring av de uppfattade hotbildernas karaktär.</p> / <p>The recent security policy debate has included a broader view of threats and risks. This study is based on the question of to what extent this was reflected in the Swedish defence bills?</p><p>This study aims to identify similarities and differences regarding expressions of threat and security related to the broader concept of security in three defence bills over the period of 1982-2009. By use of the analytical framework of Mr Barry Buzan, I aim to make a survey of the expressed values of security, their perceived threats and the arenas in which their security were to be guaranteed.</p><p>The analysis indicates diversities regarding security policy expressions. The defence bill of 1982 focuses on national values, safeguarded within the framework of Total Defence. The following defence bills indicate a change in the perceived nature of the threats and in favour of regional values and common security.</p>
3

Från totalförsvar till gemensam säkerhet : en studie av vidgade säkerhetsperspektiv / From Total Defence to Common Security : a study of broader security perspectives

Lundqvist, Stefan January 2009 (has links)
Den säkerhetspolitiska debatten har under de senaste åren tillvaratagit ett bredare perspektiv av hot och risker. Undersökningen tar sin utgångspunkt i frågan om i vilken utsträckning detta kommit till uttryck i svenska försvarspropositioner?   Undersökningen kartlägger likheter och skillnader i tre försvarspropositioners uttryck av hot och säkerhet relaterat till det vidgade säkerhetsbegreppet under perioden 1982-2009. Vid kartläggningen undersöker jag med hjälp av Barry Buzan m.fl. analysramverk för det vidgade säkerhetsbegreppet vilka säkerhetspolitiska värden som uttrycktes vara viktiga att säkerställa. Undersökningen kartlägger även hotbilderna som uppfattades mot dessa värden och inom vilka arenor deras säkerhet bedömdes kunna säkerställas. Analysen påvisar olikheter i de tre försvarspropositionernas säkerhetspolitiska uttryck. 1982 års försvarsproposition fokuserar på nationella säkerhetspolitiska värden som säkerställdes inom totalförsvarets ram. De följande försvarspropositionerna indikerar en förändring till förmån för regionala värden och gemensam säkerhet. Analysen påvisar även en radikal förändring av de uppfattade hotbildernas karaktär. / The recent security policy debate has included a broader view of threats and risks. This study is based on the question of to what extent this was reflected in the Swedish defence bills? This study aims to identify similarities and differences regarding expressions of threat and security related to the broader concept of security in three defence bills over the period of 1982-2009. By use of the analytical framework of Mr Barry Buzan, I aim to make a survey of the expressed values of security, their perceived threats and the arenas in which their security were to be guaranteed. The analysis indicates diversities regarding security policy expressions. The defence bill of 1982 focuses on national values, safeguarded within the framework of Total Defence. The following defence bills indicate a change in the perceived nature of the threats and in favour of regional values and common security.
4

Analys av fri stationsuppställning med totalstation med avseende på mätta längder och riktningar / Analysis of the configuration of free-station by totalstation regarding distance and direction observables

Broberg, Erik, Johansson, Robin January 2014 (has links)
Stationsetablering innebär bestämning av ett mätinstruments fysiska läge och orienterad riktning. I dagens bygg- och anläggningsbransch används nästan uteslutande fri station för att etablera en stationspunkt för mätningar. På en byggplats är tillgången till referensobjekt ofta begränsad. Instrumentets placering blir därför en kompromiss mellan tillgång till referensobjekt och tillgång till den plats där inmätning respektive utsättning skall ske. Denna kompromiss ger upphov till skiftande geometriska konfigurationer hos referensobjekten, vilka påverkar mätresultatet. Studiens syfte är att undersöka om simuleringar av fria stationsuppställningar i Svensk Byggnadsgeodesis (SBG:s) programvara Geo verifieras av fältmätningar och efterföljande beräkningar av osäkerhetsparametrar orsakade av konfiguration och mätta längder och riktningar. Delmål var att etablera ett testnät för att sedan genomföra simulering och fältmätning av fri stationsetablering mot. Analysen av fri stationsuppställning innefattade endast simulering och fältmätning i plan, med parametrarna X, Y och riktning. I samtliga konfigurationer verifieras simuleringarna av fältmätningarna genom att redovisade osäkerhetsellipser, till form och utbredning, överensstämmer. Detta innebär att genom simulering i SBG Geo kan svagheter i konfigurationer upptäckas och undvikas vid fältmätning, vilket är både tids- och resurssparande. Studiens slutsats är; Simulera mera. Simulering i SBG Geo visar god överensstämmelse med fältmätning och är där med ett effektivt planeringsverktyg för mätning samt att vid etablering av fri station bör referensobjekten placeras så att stationspunkten interpoleras för lägst osäkerhet. Faktorer att beakta vid fri station är, enligt studien: konfigurationen, mätningarnas kvalitet och att tillräcklig kontrollerbarhet (k-tal) föreligger / Station setup involves determination of the measuring instruments physical location and orientation. In today's construction industry free station is almost exclusively used to establish a station point for measurements. On a construction site, access to reference objects is often limited. The instruments placement therefore becomes a compromise between access to the reference objects and access to the site where surveying will take place. This compromise results in varying geometric configurations of the reference objects, which affect the results of the survey. This study aims to investigate whether the simulations of free station setups in Svensk Byggnadsgeodesis ( SBG's ) software Geo is verified by field measurements and subsequent calculations of uncertainty parameters caused by configuration and surveyed distances and directions. One objective of this study was to establish a test network of reference objects, which simulation and field measurement of free station were established against. The analysis of free station setup included only simulation and field measurement of plane surveying, with the parameters X, Y and direction. In all configurations, the simulations were verified by the field measurements by consistent corresponding of the shape of the error ellipses. This means that by simulation of SBG Geo, weaknesses in configurations can be detected and avoided during field survey, which saves both time and resources. Factors to consider when establishing free station is, according to the study: configuration, quality of the measurements and sufficient controllability (K-tal). The study concludes; simulate more. Simulation in SBG Geo show good representation of field measurements and is therefore an effective planning tool for field surveying. When establishing free station reference objects should be positioned so that the station point is interpolated for the lowest uncertainty

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