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The availability of digital cameras and the possibility to take photos at no cost lead to an increasing amount of digital photos online and on private computers. The pure amount of data makes approaches that support users in the administration of the photo necessary. As the automatic understanding of photo content is still an unsolved task, metadata is needed for supporting administrative tasks like search or photo work such as the generation of photo books. Meta-information textually describes the depicted scene or consists of information on how good or interesting a photo is.
In this thesis, an approach for creating meta-information without additional effort for the user is investigated. Eye tracking data is used to measure the human visual attention. This attention is analyzed with the objective of information creation in the form of metadata. The gaze paths of users working with photos are recorded, for example, while they are searching for photos or while they are just viewing photo collections.
Eye tracking hardware is developing fast within the last years. Because of falling prices for sensor hardware such as cameras and more competition on the eye tracker market, the prices are falling, and the usability is increasing. It can be assumed that eye tracking technology can soon be used in everyday devices such as laptops or mobile phones. The exploitation of data, recorded in the background while the user is performing daily tasks with photos, has great potential to generate information without additional effort for the users.
The first part of this work deals with the labeling of image region by means of gaze data for describing the depicted scenes in detail. Labeling takes place by assigning object names to specific photo regions. In total, three experiments were conducted for investigating the quality of these assignments in different contexts. In the first experiment, users decided whether a given object can be seen on a photo by pressing a button. In the second study, participants searched for specific photos in an image search application. In the third experiment, gaze data was collected from users playing a game with the task to classify photos regarding given categories. The results of the experiments showed that gaze-based region labeling outperforms baseline approaches in various contexts. In the second part, most important photos in a collection of photos are identified by means of visual attention for the creation of individual photo selections. Users freely viewed photos of a collection without any specific instruction on what to fixate, while their gaze paths were recorded. By comparing gaze-based and baseline photo selections to manually created selections, the worth of eye tracking data in the identification of important photos is shown. In the analysis of the data, the characteristics of gaze data has to be considered, for example, inaccurate and ambiguous data. The aggregation of gaze data, collected from several users, is one suggested approach for dealing with this kind of data.
The results of the performed experiments show the value of gaze data as source of information. It allows to benefit from human abilities where algorithms still have problems to perform satisfyingly.
In an attempt to put pronunciation training back in the limelight and to engage in a fruitful discussion on pronunciation- equal importance with other language skills, the current research project focuses on pronunciation. Specifically, one area that causes problems for L1-German speakers is concentrated on, namely the central approximant. German learners should not despair too much as even many native-English children stumble with /r/. For some, acquiring this sound takes a long time and even some professional help (see Secord 2007: 7-8). One problem that these children have is the substitution of /r/ with /w/. "Children with developmental speech substitution," write Raphael et al., "often produce the more easily articulated (…) /w/ for /r/" (2011: 119). Most native-English children require a long time to acquire this sound. According to Bleile, /r/ belongs to the last stage (i.e. stage 4) of a child- language development (see Bleile 2004: 106). This final stage can range from five years of age to adolescence. One of the greatest difficulties, for instance, occurs with postvocalic /r/ (or "[r] colored schwa") and consonant clusters with /r/ (see Bleile 2004: 106).
It is important at this juncture to direct attention to the organization of the current research project and how it addresses the /r/-problem. At the start of the current study, an appropriate and concise definition of the /r/-sound is proposed. While it can be easily stated that the letter <r> is the 18th letter in the English alphabet, it is much more arduous to define what is meant by the /r/-sound. In chapter 2, a number of definitions of /r/ are explored. Section 2.1 presents an articulatory description and section 2.2 offers an acoustic description. A theoretical definition is provided in section 2.3. By exploring the distinguishing features of the /r/-sound, it can be distinguished from other sounds. From these three perspectives, a more encompassing view of the complicated English /r/-sound can be obtained.
In chapter 3, three hypotheses are presented. The first two are the main hypotheses for the current study. There is also a third (minor) hypothesis and it is an offshoot from some of the research findings from the first hypothesis. In section 3.1.1, hypothesis 1 (H1) investigates the frequency of the problem that L1-German speakers have when speaking the American English /r/-sound aloud when it is postvocalic and in a weakened syllable. Hypothesis 2 (H2) is put forward in section 3.1.2. It explores the frequency of /w/-substitution for /r/ when the latter sound is prevocalic in a stressed syllable. For the final and third hypothesis (H3), one specific occassion where L1 interference occurs (i.e. /ɐ/ for /ə/) is researched in section 3.1.3.
Some organizational details concerning the study are also included in the third chapter. The general set-up of the study is provided in section 3.2.1. Information pertaining to both the disqualified participants of the study as well as the 50 test subjects who were selected for the study is available in section 3.2.1.2. Details on technical equipment and software programs are disclosed in sections 3.2.1.1 and 3.2.1.3. The prescribed reading texts that the test subjects needed to read aloud are presented in the subsections of section 3.2.2.
For a better understanding of the acoustic properties of the prevocalic /r/-sound, five expressions from the reading text are selected. In section 3.3, the expressions are also articulated by the author (a native speaker of a variety of English from North America) in four different scenarios. The scenarios try to illustrate a limited number of possible articulatory variations. The author utters the expressions in four different ways: 1.) with lip spreading, 2.) in isolation, 3.) in connected speech and 4.) with /w/-substitution for /r/. These articulations serve as a template for understanding how the acoustic features of /r/ changes. Some of these changes are noticeable in the articulations of the test subjects (presented in chapter 4).
In chapter 4, the data collected for the three hypotheses are presented. For H1, section 4.1 and its subsections document the formant readings of a number of English expressions which contain the postvocalic /r/. In this analysis, it is important to detect where the central approximant is elided. In cases of elision, the samples have their schwa-like sounds plotted in a vowel quadrilateral, so that their locations can be detected. In section 4.2 and its subsections, data observations for H2 are discussed. From these data, the extent of /w/-substitution for /r/ when it is prevocalic in a stressed syllable can be observed. In section 4.3, an analysis of the /ɐ/-sound from three German expressions as they are spoken by the 50 test subjects is presented for H3. Together with pertinent data (i.e. formant readings) from H1, a comparison is made between the locations of /ə/ and /ɐ/. This section concludes with a plotting of all samples of these two vowels in a vowel chart.
In the final chapter of the current study, the main findings of the three hypotheses are summarized. Chapter 5 also provides some insights into a few of the gaps or limitations in the present research. Future research endeavors are proposed in order to suggest possible avenues to advance the findings reported on in the fourth chapter. In addition, several teaching suggestions and pronunciation exercises for implementing the /r/-sound in class are presented.
Lastly, there is an appendix section that consists of 14 smaller appendices (i.e Volume 2). The spectrograms and formant readings for each expression spoken by each of the 50 test subjects are documented in Appendix A to M. In Appendix N, some charts, tables, diagrams, etc. that are discussed throughout the following chapters are made available. Copies of the original questionnaire that were filled out by the test subjects are also in Appendix N.
Der Apple ][ war einer der drei ersten kompletten Computersysteme auf dem Markt. Von April 1977 an wurde er rund 16 Jahre lang mehrere Millionen mal verkauft. Entwickelt wurde dieser 8 Bit Homecomputer von Steve Wozniak und Steve Jobs. Sie ebneten damit den Weg für den Macintosh und das heute gut bekannte Unternehmen Apple.
Diese Arbeit beschreibt die Implementierung eines Softwareemulators für das komplette Apple ][ Computersystem auf nur einem Atmel AVR Microcontroller. Die größte Herausforderung besteht darin, dass der Microcontroller nur eine geringfügig höhere Taktrate als die zu emulierende Hardware hat. Dies erfordert eine effiziente Emulation der CPU und Speicherverwaltung, die nachfolgend zusammen mit der Laufzeitumgebung für die Emulation vorgestellt wird. Weiterhin wird die Umsetzung des Emulators mit Display und Tastatur in Hardware naher erläutert.
Mit dieser Arbeit wird die erfolgreiche Entwicklung eines portablen Apple ][ Emulators, von der Software über die Hardware bis hin zu einem Prototypen, vorgestellt.
The way information is presented to users in online community platforms has an influence on the way the users create new information. This is the case, for instance, in question-answering fora, crowdsourcing platforms or other social computation settings. To better understand the effects of presentation policies on user activity, we introduce a generative model of user behaviour in this paper. Running simulations based on this user behaviour we demonstrate the ability of the model to evoke macro phenomena comparable to the ones observed on real world data.
Field margins are often the only remaining habitats of various wild plant species in agricultural landscapes. However, due to their proximity to agricultural fields, the vegetation of field margins can be affected by agrochemicals applied to the crop fields. The aim of this thesis was to investigate the individual and combined effects of herbicide, insecticide and fertilizer inputs on the plant community of a field margin. Therefore, a 3-year field experiment with a randomized block design including seven treatments (H: herbicide, I: insecticide, F: fertilizer, H+I, F+I, F+H and F+H+I) and one control was conducted on a low-production meadow. Each treatment was replicated 8 times in 8 m x 8 m plots with a distance of 2 m between each plot. The fertilizer rates (25 % of the field rate) and pesticide rates (30 % of the field rate) used for the plot applications were consistent with realistic average input rates (overspray + drift) in the first meter of a field margin directly adjacent to a wheat field.
The study revealed that fertilizer and herbicide misplacements in field margins are major factors that affect the natural plant communities of these habitats. In total, 20 of the 26 abundant species on the study site were significantly affected by the fertilizer and herbicide treatment. The fertilizer promoted plants with high nutrient uptake and decreased the frequencies of small species. The herbicide caused a nearly complete disappearance of three species directly after the first application, whereas sublethal effects (e.g., phytotoxic effects and reduced seed productions of up to 100 %) were observed for the other affected species. However, if field margins are exposed to repeated agrochemical applications over several years, then such sublethal effects (particularly reproduction effects) also reduce the population size of plant species significantly, as observed in this study.
Significant herbicide-fertilizer interaction effects were also detected and could not be extrapolated from individual effects. The fertilizer and herbicide effects became stronger over time, leading to shifts in plant community compositions after three years and to a 15 % lower species diversity than in the control. The insecticide significantly affected the frequencies of two plant species (1 positively and 1 negatively). The results of the experiment suggest that a continuous annual agrochemical application on the study site would cause further plant community shifts and would likely lead to the disappearance of certain affected plants. A clear trend of increasing grass dominance at the expense of flowering herbs was detected. This finding corresponds well with monitoring data from field margins near the study site.
Although herbicide risk assessment aims to protect non-target plants in off-field habitats from adverse effects, reproduction effects and combined effects are currently not considered. Furthermore, no regulations for fertilizer applications next to field margins exist and thus, fertilizer misplacements in field margins are likely to occur and to interact with herbicide effects.
Adaptations of the current risk assessment, a development of risk mitigation measures (e.g., in-field buffers) for the application of herbicides and fertilizers, and general management measures for field margins are needed to restore and conserve plant diversity in field margins in agricultural landscapes.
Modeling and publishing Linked Open Data (LOD) involves the choice of which vocabulary to use. This choice is far from trivial and poses a challenge to a Linked Data engineer. It covers the search for appropriate vocabulary terms, making decisions regarding the number of vocabularies to consider in the design process, as well as the way of selecting and combining vocabularies. Until today, there is no study that investigates the different strategies of reusing vocabularies for LOD modeling and publishing. In this paper, we present the results of a survey with 79 participants that examines the most preferred vocabulary reuse strategies of LOD modeling. Participants of our survey are LOD publishers and practitioners. Their task was to assess different vocabulary reuse strategies and explain their ranking decision. We found significant differences between the modeling strategies that range from reusing popular vocabularies, minimizing the number of vocabularies, and staying within one domain vocabulary. A very interesting insight is that the popularity in the meaning of how frequent a vocabulary is used in a data source is more important than how often individual classes and properties arernused in the LOD cloud. Overall, the results of this survey help in understanding the strategies how data engineers reuse vocabularies, and theyrnmay also be used to develop future vocabulary engineering tools.
Diffusion imaging captures the movement of water molecules in tissue by applying varying gradient fields in a magnetic resonance imaging (MRI)-based setting. It poses a crucial contribution to in vivo examinations of neuronal connections: The local diffusion profile enables inference of the position and orientation of fiber pathways. Diffusion imaging is a significant technique for fundamental neuroscience, in which pathways connecting cortical activation zones are examined, and for neurosurgical planning, where fiber reconstructions are considered as intervention related risk structures.
Diffusion tensor imaging (DTI) is currently applied in clinical environments in order to model the MRI signal due to its fast acquisition and reconstruction time. However, the inability of DTI to model complex intra-voxel diffusion distributions gave rise to an advanced reconstruction scheme which is known as high angular resolution diffusion imaging (HARDI). HARDI received increasing interest in neuroscience due to its potential to provide a more accurate view of pathway configurations in the human brain.
In order to fully exploit the advantages of HARDI over DTI, advanced fiber reconstructions and visualizations are required. This work presents novel approaches contributing to current research in the field of diffusion image processing and visualization. Diffusion classification, tractography, and visualizations approaches were designed to enable a meaningful exploration of neuronal connections as well as their constitution. Furthermore, an interactive neurosurgical planning tool with consideration of neuronal pathways was developed.
The research results in this work provide an enhanced and task-related insight into neuronal connections for neuroscientists as well as neurosurgeons and contribute to the implementation of HARDI in clinical environments.
This study explored the question whether greenhouse gas mitigation projects in Namibia could be initiated through local economic development programmes. In particular, research was done on whether the Clean Development Mechanism (CDM) of the Kyoto Protocol could play an essential role in the promotion of such mitigation projects.
In a first step supporting and inhibiting factors (potential for mitigation projects, business and investment climate, institutions, etc.) were discussed, which have a negative or positive influence on mitigation projects. In a second step the mind-set of climate and energy experts as well as of local economic development experts and practitioners was analysed with regard to the research questions. To this end, 229 questionnaires, 28 interviews and the output of a focus group discussion with 20 participants were evaluated. Additionally, the author conducted a real life case study to investigate the practicability of initiating greenhouse gas mitigation projects through local economic development efforts. Parallel to the development of an economic development strategy in the Namibian region of Otjozondjupa, the potential for greenhouse gas mitigation projects was explored. Based on the outcome of this investigation project ideas were developed and their potential socio-economic impact was evaluated. Promising projects were then included into the development strategy.
Due to various factors such as the complexity of CDM, low greenhouse gas emissions in Namibia, the low price of emission rights and insufficient financial means it is unlikely that CDM projects can be initiated through local economic development initiatives in Namibia. However, many stakeholders consider the idea of interlinking mitigation projects and local economic development initiatives favourably as long as such projects support the broader objectives of those initiatives. This research has shown that locally initiated mitigation projects do not contribute much to employment or income generation at the local level in Namibia. Thus, national strategic objectives should be considered, such as improving access to electricity to all strata of society or becoming less dependent on electricity imports. This requires, however, that local economic development strategies also cover the energy sector, that local governments are willing and capacitated to initiate mitigation projects, that national and local public institutions work together more closely, that national and local economic framework conditions are improved so as to attract private investments, and that the experiences and interests of the relevant stakeholders are considered throughout the project development process.
Mathematical Modelling of GIS Tailored GUI Design with the Application of Spatial Fuzzy Logic
(2014)
This PhD thesis is situated within the framework of the Research-Group Learning and Neurosciences (ReGLaN)-Health and Logistics project. The goal of this project is the optimisation of health service delivery in the rural areas of South Africa. Cooperation takes place between ReGLaN-Health and Logistics and the South African Council for Scientific and Industrial Research (CSIR) Meraka Institute, with Prof Dr Dr Marlien Herselman of Pretoria, South Africa, as the central contact person. This thesis deals with the mathematical modelling of Geographic Information System (GIS)-tailoredrnGraphical User Interface (GUI) design with the application of spatial fuzzy logic. This thesis considers the mathematical visualisation of risk and resource maps for epidemiological issues using GIS and adaptive GUI design for an Open Source (OS) application for digital devices. The intention ofrnthis thesis is to provide spatial decision support tailored to different user groups. In order for the GUI elements to be evaluated and initialised, empirical teaching-learning-research on dealing with geomedia and GUI elements was conducted.
Through the increasing availability of access to the web, more and more interactions between people take place in online social networks, such as Twitter or Facebook, or sites where opinions can be exchanged. At the same time, knowledge is made openly available for many people, such as by the biggest collaborative encyclopedia Wikipedia and diverse information in Internet forums and on websites. These two kinds of networks - social networks and knowledge networks - are highly dynamic in the sense that the links that contain the important information about the relationships between people or the relations between knowledge items are frequently updated or changed. These changes follow particular structural patterns and characteristics that are far less random than expected.
The goal of this thesis is to predict three characteristic link patterns for the two network types of interest: the addition of new links, the removal of existing links and the presence of latent negative links. First, we show that the prediction of link removal is indeed a new and challenging problem. Even if the sociological literature suggests that reasons for the formation and resolution of ties are often complementary, we show that the two respective prediction problems are not. In particular, we show that the dynamics of new links and unlinks lead to the four link states of growth, decay, stability and instability. For knowledge networks we show that the prediction of link changes greatly benefits from the usage of temporal information; the timestamp of link creation and deletion events improves the prediction of future link changes. For that, we present and evaluate four temporal models that resemble different exploitation strategies. Focusing on directed social networks, we conceptualize and evaluate sociological constructs that explain the formation and dissolution of relationships between users. Measures based on information about past relationships are extremely valuable for predicting the dissolution of social ties. Hence, consistent for knowledge networks and social networks, temporal information in a network greatly improves the prediction quality. Turning again to social networks, we show that negative relationship information such as distrust or enmity can be predicted from positive known relationships in the network. This is particularly interesting in networks where users cannot label their relationships to other users as negative. For this scenario we show how latent negative relationships can be predicted.