Interactive Visualization of Graph Pyramids

Hierarchies of plane graphs, called graph pyramids, can be used for collecting, storing and analyzing geographical information based on satellite images or other input data. The visualization of graph pyramids facilitates studies about their structure, such as their vertex distribution or height in relation of a specific input image. Thus, a researcher can debug algorithms and ask for statistical information. Furthermore, it improves the better understanding of geographical data, like landscape properties or thematical maps. In this paper, we present an interactive 3D visualization tool that supports several coordinated views on graph pyramids, subpyramids, level graphs, thematical maps, etc. Additionally, some implementation details and application results are discussed

Women Leading in Silence in Papua New Guinea Higher Education

The Constitution of the Independent State of Papua New Guinea (National Goals and Directive Principles, the Preamble of the PNG Constitution, 1975) and the National Gender Equity Policy (2003) advocate for the increase of women's representation in educational leadership positions in higher education institutions. However, that has not been the case because leadership opportunities have not been fully extended to the women academics in the higher education sector. This research explored the experiences of women in formal leadership positions and aspiring women leaders. The study examined what influenced women's access to leadership roles within the higher education in Papua New Guinea (PNG) and how this impacted their career advancement within the leadership structure. It also explored the beliefs and perceptions women held towards leadership, and investigated what factors influenced these. This research used a qualitative approach to gather data in Papua New Guinea from April - June 2009. The interviews were conducted with five women who were in formal leadership positions and eight aspiring women leaders in one university. Data was analyzed using a thematic analysis approach. A major finding was that the socio-cultural context had a powerful influence on women's educational leadership experiences in PNG. It impacted on women's values and beliefs in leadership which were significantly influenced by the Christian and Melanesian cultural value systems. As a result, women associated leadership with collaborative and servant leadership approaches. Some key findings illustrated how power was wielded over women in family settings, and through 'big man' leadership which in turn, impacted women's leadership aspirations. Furthermore, the appointment process and the lack of support systems such as mentoring and networking for women in the institution disadvantaged women to progress in their careers. There were other factors such as gender discrimination, the challenges of balancing family/work and lack of confidence which created barriers for women's advancement to leadership positions. Overall, this study has shown that Papua New Guinea patriarchal society by large has effects on the women educational leaders in the higher education sector

Feasibility study of the dual active bridge as a low-frequency sine wave inverter

A dissertation submitted n fulfilment of the requirements for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, University of Witwatersrand, Johannesburg, 2018The conventional Sinusoidal PulseWidth Modulation (SPWM) inverter is limited by the fact that it does not allow for Zero Voltage Switching. This means that the switching frequency is kept low to reduce the switching losses. As a consequence of holding these switching frequencies low, the distribution of power over the frequency spectrum is kept closer to the fundamental frequency (compared to higher switching frequencies) leading to larger reactive components to filter out these harmonics. The use of high-frequency switching, Zero Voltage Switching, and different modulation schemes can lead to higher power densities. This research investigates under what conditions the use of these techniques in a Dual Active Bridge (DAB) inverter might lead to a higher power density than the SPWM. Volumetric approximations for the different circuit components in the investigated inverter topologies are demonstrated. These approximations are used to design circuits using physical volume as the cost function where possible. Additionally, a loss model is derived to determine the expected efficiency of each topology being investigated. This model is related to the power density since it is directly proportional to the size of heat sink required to cool the inverter. The techniques for improving power density mentioned above are presented, and the impact that they have on power density is shown using the volumetric approximation function. From this approximation, the volumes between the DAB and the SPWM are compared and investigations into where the DAB may have a higher power density have been performed. It was found that the DAB was not smaller than the SPWM for frequencies less than 72kHz. When simulating the converters operating at different frequencies, the general trend is that the SPWM increases in volume as the frequency increases, whereas, the DAB decreases in volume as the frequency increases. An exact frequency at which the DAB would be smaller than the SPWM was not found in this research. However, many conclusions have been drawn around the use of a DAB as an inverter and the strengths and shortcomings it provides. The modulation scheme would need to be modified to reduce the losses and provide a more competitive volume. Additionally, multi-level and multi-stage techniques could be used to reduce the volume further.MT 201

Text visualization techniques: Taxonomy, visual survey, and community insights

Figure 1: The web-based user interface of our visual survey called Text Visualization Browser. By using the interaction panel on the left hand side, researchers can look for specific visualization techniques and filter out entries with respect to a set of categories (cf. the taxonomy given in Sect. 3). Details for a selected entry are shown by clicking on a thumbnail image in the main view. The survey contains 141 categorized visualization techniques by January 19, 2015. Text visualization has become a growing and increasingly impor-tant subfield of information visualization. Thus, it is getting harder for researchers to look for related work with specific tasks or vi-sual metaphors in mind. In this paper, we present an interactive visual survey of text visualization techniques that can be used for the purposes of search for related work, introduction to the subfield and gaining insight into research trends. We describe the taxonomy used for categorization of text visualization techniques and com-pare it to approaches employed in several other surveys. Finally, we present results of analyses performed on the entries data

User Preferences of Spatio-Temporal Referencing Approaches For Immersive 3D Radar Charts

The use of head-mounted display technologies for virtual reality experiences is inherently single-user-centred, allowing for the visual immersion of its user in the computer-generated environment. This isolates them from their physical surroundings, effectively preventing external visual information cues, such as the pointing and referral to an artifact by another user. However, such input is important and desired in collaborative scenarios when exploring and analyzing data in virtual environments together with a peer. In this article, we investigate different designs for making spatio-temporal references, i.e., visually highlighting virtual data artifacts, within the context of Collaborative Immersive Analytics. The ability to make references to data is foundational for collaboration, affecting aspects such as awareness, attention, and common ground. Based on three design options, we implemented a variety of approaches to make spatial and temporal references in an immersive virtual reality environment that featured abstract visualization of spatio-temporal data as 3D Radar Charts. We conducted a user study (n=12) to empirically evaluate aspects such as aesthetic appeal, legibility, and general user preference. The results indicate a unified favour for the presented location approach as a spatial reference while revealing trends towards a preference of mixed temporal reference approaches dependent on the task configuration: pointer for elementary, and outline for synoptic references. Based on immersive data visualization complexity as well as task reference configuration, we argue that it can be beneficial to explore multiple reference approaches as collaborative information cues, as opposed to following a rather uniform user interface design.Comment: 29 pages, 9 figures, 1 tabl

TACKLING THE EXPLORATION OF FOOTBALL PLAYER DISC PROFILES

The purpose of this particular study was to examine the DiSC styles of intercollegiate football players. This study observed the DiSC assessment results of 127 collegiate football players, categorized into Dominance (D), influence (i), Steadiness (S), and Conscientiousness (C). There were 127 points of data used to analyze DiSC style based on the eight different positions as well as offense compared to defense. After completing chi-square analyses, there were two outputs that were significantly different from the sample mean. Most notably, it was shown that the Dominance based quarterbacks were significant. While no significance was found between offensive and defensive units. Overall, this study adds to the literature demonstrating the vast heterogeneity of members of a football team.Master of Art

Designing a 3D Gestural Interface to Support User Interaction with Time-Oriented Data as Immersive 3D Radar Chart

The design of intuitive three-dimensional user interfaces is vital for interaction in virtual reality, allowing to effectively close the loop between a human user and the virtual environment. The utilization of 3D gestural input allows for useful hand interaction with virtual content by directly grasping visible objects, or through invisible gestural commands that are associated with corresponding features in the immersive 3D space. The design of such interfaces remains complex and challenging. In this article, we present a design approach for a three-dimensional user interface using 3D gestural input with the aim to facilitate user interaction within the context of Immersive Analytics. Based on a scenario of exploring time-oriented data in immersive virtual reality using 3D Radar Charts, we implemented a rich set of features that is closely aligned with relevant 3D interaction techniques, data analysis tasks, and aspects of hand posture comfort. We conducted an empirical evaluation (n=12), featuring a series of representative tasks to evaluate the developed user interface design prototype. The results, based on questionnaires, observations, and interviews, indicate good usability and an engaging user experience. We are able to reflect on the implemented hand-based grasping and gestural command techniques, identifying aspects for improvement in regard to hand detection and precision as well as emphasizing a prototype's ability to infer user intent for better prevention of unintentional gestures.Comment: 30 pages, 6 figures, 2 table

10241 Abstracts Collection -- Information Visualization

From 13.06.10 to 18.06.10, the Dagstuhl Seminar 10241 ``Information Visualization \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Controlling In-Vehicle Systems with a Commercial EEG Headset: Performance and Cognitive Load

Humans have dreamed for centuries to control their surroundings solely by the power of their minds. These aspirations have been captured by multiple science fiction creations, such as the Neuromancer novel by William Gibson or the Brainstorm cinematic movie, to name just a few. Nowadays, these dreams are slowly becoming reality due to a variety of brain-computer interfaces (BCI) that detect neural activation patterns and support the control of devices by brain signals. An important field in which BCIs are being successfully integrated is the interaction with vehicular systems. In this paper, we evaluate the performance of BCIs, more specifically a commercial electroencephalographic (EEG) headset in combination with vehicle dashboard systems, and highlight the advantages and limitations of this approach. Further, we investigate the cognitive load that drivers experience when interacting with secondary in-vehicle devices via touch controls or a BCI headset. As in-vehicle systems are increasingly versatile and complex, it becomes vital to capture the level of distraction and errors that controlling these secondary systems might introduce to the primary driving process. Our results suggest that the control with the EEG headset introduces less distraction to the driver, probably as it allows the eyes of the driver to remain focused on the road. Still, the control of the vehicle dashboard by EEG is efficient only for a limited number of functions, after which increasing the number of in-vehicle controls amplifies the detection of false commands

Learning by generation in computer science education

The use of generic and generative methods for the development and application of interactive educational software is a relatively unexplored area in industry and education. Advantages of generic and generative techniques are, among other things, the high degree of reusability of systems parts and the reduction of development costs. Furthermore, generative methods can be used for the development or realization of novel learning models. In this paper, we discuss such a learning model that propagates a new way of explorative learning in computer science education with the help of generators. A realization of this model represents the educational software GANIFA on the theory of generating finite automata from regular expressions. In addition to the educational system's description, we present an evaluation of this system.Facultad de Informátic