In this thesis, we explore some of the effects of virtual environment displays, specifically the head-mounted display (HMD) and the Cave Automatic Virtual Environment (CAVE), on 3D interaction tasks involving selection and manipulation. The motivation for this thesis comes from the lack of previous work that has studied the effects of differences between the HMD and the CAVE on 3D interaction tasks. We conducted three user studies to determine how the differences between these two displays affect selection and manipulation in a 3D environment. Our first study demonstrates that 3D selection and manipulation tasks can be affected by the display type. Our second user study shows that task performance can suffer when a selection and manipulation technique is migrated to a display for which it is not intended. The third user study we conducted suggests that we can modify a selection and manipulation technique and improve its usability in the display to which it is migrated. We conclude with a set of guidelines to ease the migration of selection and manipulation techniques from the HMD to the CAVE while trying to maintain usability. / Master of Science

Information visualization (info vis) deals with how to increase the bandwidth of effective communication between computer and human, enabling us to see more, understand more, and accomplish more. Traditionally, it deals with interaction and display techniques of visualizing often abstract data on the two-dimensional desktop. Immersive virtual environments (VEs) offer new, exciting possibilities for information visualization. Immersion gives an enhanced realistic effect, and can improve spatial understanding and orientation. By identifying or developing useful interaction techniques (ITs), we can develop VE systems for better information visualization. This thesis has two different experiments that were related to two different sides of the study of use of immersion for VEs. One of the experiments is related to abstract data visualization in an immersive VE. The other one was motivated by the need for enhancing a realistic VE with additional data. In our first experiment, our focus is on implementing overview+detail techniques in VEs. Our hypothesis is that VE-specific ITs should borrow from, but not copy existing 2D IT technique for overview +detail. We develop ITs for use in VEs and show that they are easy to use and useful using task-based usability evaluation. We develop the "jump" technique for use in this application, which can be generalized to numerous other applications. The tangible contribution of this research is Wizard, an application for infovis in VEs. Our second hypothesis is that if the data to be visualized has inherent spatial attributes, it can be visualized well in immersive virtual environments. We investigate the trends using an experiment that tests people's understanding of spatial attributes under immersive and desktop conditions. Although not statistically significant, we observed a moderate trend indicating that immersion decreases the time needed to perform a spatial information- gathering task. We believe that this area of research can be applied immediately to the applications currently being developed. / Master of Science

Large-scale wireless sensor networks (WSNs) are highly vulnerable to attacks because they consist of numerous resource-constrained devices and communicate via wireless links. These vulnerabilities are exacerbated when WSNs have to operate unattended in a hostile environment, such as battlefields. In such an environment, an adversary poses a physical threat to all the sensor nodes. An adversary may capture any node, compromising critical security data including keys used for encryption and authentication. Consequently, it is necessary to provide security services to these networks to ensure their survival. We propose a novel, self-organizing key management scheme for large-scale and long-lived WSNs, called Survivable and Efficient Clustered Keying (SECK). SECK provides administrative services that ensures the survivability of the network. SECK is suitable for managing keys in a hierarchical WSN consisting of low-end sensor nodes clustered around more capable gateway nodes. Using cluster-based administrative keys, SECK provides five efficient security administration mechanisms: 1) clustering and key setup, 2) node addition, 3) key renewal, 4) recovery from multiple node captures, and 5) re-clustering. All of these mechanisms have been shown to localize the impact of attacks and considerably improve the efficiency of maintaining fresh session keys. Using simulation and analysis, we show that SECK is highly robust against node capture and key compromise while incurring low communication and storage overhead. / Master of Science

Virtual City Environments (VCEs) and Mirror Worlds can be a useful resource for communities such as the local government, researchers and the general public to collaborate on tasks like town planning, threat assessment, commerce and research. There are open standards like Extensible 3D (X3D, which represents 3D graphics) and CityGML (a Geography Markup Language to manage 3D building data). These standards are royalty-free and used to create, manage, share and portray such environments. However, there are critical challenges to delivering such complex and detailed Mirror Worlds in real-time. In this work, we focus on runtime data structures and performance for Level-of-Detail (LOD) management and real-time portrayal. We begin with a VCE defined in existing semantic models such as the CityGML specification. We implement and evaluate a novel X3D-based Level-of-Detail technique called ProxyPrismLOD, which leverages the CityGML standard of a 4-step LOD hierarchy. For switching between different models of the same object at near ranges, our LOD technique uses a custom shape we call a ProxyPrism to optimally encapsulate irregularly and asymmetrically shaped building models. First, we ran a user study to understand the visual dynamics of range-based LOD switching. Specifically, we evaluated several scaling factors for an exponential range cutoff function. The function is based on the model's size as well as the environment density. In this experiment, participants rated "visual granularity" and "distraction" levels of the LOD technique over two Software Field-of-View (sFOV) conditions. A scaling factor of Beta = 3 was determined. Second, we ran a series of simulations to study the performance benefits of ProxyPrismLOD technique over the basic range-based LOD. We observed performance benefits up to 7.46% in terms of overall Frames-per-Seconds (FPS) on the models we tested. / Master of Science

Wearable computers allow users the freedom to work in any environment including hazardous environments that may require protective clothing. Past research has shown that protective clothing interferes with manual materials handling tasks, medical tasks, and manual dexterity tasks. However, little information exists regarding how protective clothing affects task performance with wearable input devices. As a result, a study was conducted to address this issue and offer recommendations to enhance the compatibility of chemical protective clothing and wearable input devices. Sixteen active-duty soldiers performed a text-entry task with a wearable mouse and touch pad, while bare handed, wearing 7-mil, 14-mil, and 25-mil chemical protective gloves, wearing a respirator alone, and wearing the respirator and each of three gloves. Upon completion of the experiment, participants rated task difficulty, confidence using the input device, and input device preference. Task completion times were 9% slower with the 25-mil glove than the 7-mil glove. Text entry was not perceived as difficult when bare handed, or wearing the 7-mil and 14-mil gloves, suggesting that thin chemical protective gloves (i.e. 7-mil and 14-mil) are more suitable than thicker gloves for use with wearable input devices. When using the touch pad, task completion times were 17% faster than when using the mouse. Subjective ratings of difficulty, confidence, and preference provide strong support for the use of a touch pad input device rather than a mouse. / Master of Science

Yes / In recent years, there has been significant attention given to stakeholder management, which involves the intricate interaction between organisations and individuals, as well as diverse groups that can significantly affect or shape an organisation's decisions. While progress has been made, African countries are seen as the next promising frontier for progress and advancement. Nevertheless, there remains a lack of understanding of this concept, as the continent is undergoing remarkable economic growth. Entrepreneurs operating in such environments face intricate landscapes when it comes to stakeholder management. Consequently, understanding how stakeholders contribute to the growth of entrepreneurial ventures in Africa is crucial to promote sustainable and responsible business practices. This chapter presents insights that can stimulate future research on stakeholder management within the intricate and diverse African setting. The chapter conceptualises the relationship between stakeholders and entrepreneurship in Africa and shows how entrepreneurial firms navigate the challenges associated with weak institutional environments. / The full-text of this book chapter will be released for public view at the end of the publisher embargo on 7 Jun 2025.

No / This paper draws a comparison between the 700-year-old historically reported will-o'-the-wisp phenomenon and the more recent discovery of extremophilic colonization of hostile environments; both have been observed as present in isolated, stressed environmental regions and originating from biological phenomena. However, whereas extremophilic activity can be understood in terms of a survival strategy based upon the synthesis of specific suites of protective biochemicals which are designed to control biogeologically the stressed habitats and to provide protection against the extreme environments, the analytical techniques that have proved so successful for the illumination of these survival strategies of extremophiles and which are now being miniaturized for in-field studies and for extraterrestrial exploration have not been applied to a clarification or evaluation of the phenomenon of will-o'-the-wisp. The reason is simply that the will-o'-the-wispsightings have now disappeared completely. Tantalizingly, all of the most reasonable physico-chemical and biological explanations for the will-o'-the-wisp phenomenon proved to be unsatisfactory in some respect and it is clear that, just as in the case of extremophilic colonization, will-o'-the-wisp would benefit from a modern rigorous analytical study which would produce the data from which the potentially novel biological behaviour could be characterized and which would help a better understanding to be made of our natural world.

As large displays become more affordable, researchers investigate their effects on productivity and try to develop techniques for making the large display user experience more effective. Recent work has demonstrated significant productivity benefits, but has also identified numerous usability issues with current software design not scaling well. Studies show that large displays enable users to create and manage more windows, as well as to engage in more complex multitasking behavior. In this thesis, we developed some user interface design guidelines for large shared displays. Specifically, empirical studies to compare the effects of using large shared displays against personal displays when each of them is used as a secondary display are presented, showing that large shared display impose higher interruption and comprehension to the user. Empirical and qualitative studies are designed to develop two user interface design guidelines for large shared displays. We designed a system called SuperTrack that uses LSD along with the guidelines to further enhance and improve team efficiency and productivity in collaborative software development environments. Finally, an in-situ evaluation assesses the benefits of SuperTrack based on our developed design guidelines in terms of improving software development efficiency and productivity. Results show that by exposing software development team members to a large shared display, a system that follows our developed user interface guidelines leads to higher communication among the team members and improved group awareness, leading to higher productivity and efficiency. / Master of Science

Developing economical yet effective methods of incorporating usability engineering as an integral part of software engineering is a primary focus of human-computer interaction (HCI) research. However, much HCI research has focused primarily on inspecting and evaluating applications supporting command-line or graphical user interface (GUI) interaction styles. With the dramatic increase in virtual environment (VE) research in recent years, the HCI community is beginning to place an added emphasis on creating methodologies to ensure usability in VE development. While the demand for VE-specific usability engineering methods and criteria is dire as the amount of money invested by military, government, commercial, and industrial organizations continues to grow, widely accepted methodologies for assessing VE usability are, at this point in time, minimal. There has been a recent increase in research discussing the need of VE-specific usability engineering methodologies, but few research projects have concentrated their efforts on providing such methodologies. Therefore, application developers attempting to apply a user-centered design approach in constructing VEs must often perform largely ad-hoc assessments or in-house evaluations using existing non-VE-specific usability engineering methodologies. The primary focus of this research was to develop a method to guide usability engineering of VEs. The strategy used to develop this usability evaluation method was to modify existing usability evaluation methodologies to support VE development by leveraging the results of previous VE usability research performed at Virginia Tech and elsewhere. The result was a VE-specific usability evaluation methodology that encompasses two existing usability assessment techniques: usability inspections and formative evaluations. We applied this methodology to Crumbs, an immersive visualization VE developed at the National Center for Supercomputing Applications (NCSA). A multi-dimensional framework of VE usability characteristics was a topic of research at Virginia Tech. This framework provided the backbone for VE-specific modifications to the existing usability evaluation techniques proposed in this research. Framework design guidelines permitted usability specialists to perform guidelines-based usability inspections of Crumbs. Results gathered from the guidelines-based usability inspections were used not only to redesign the Crumbs user interface but also drive creation of a formative evaluation plan. Application of the methodology not only uncovered usability issues with Crumbs, but also provided invaluable information regarding the effectiveness of the methodology itself. We conclude this thesis by describing a usability evaluation methodology, called the Modified Concept Book Usability Evaluation Methodology, proposed to improve the usability evaluation methodology performed on Crumbs and other VEs. Our methodology was adapted from an established methodology for performing content analysis on a large volume of qualitative data. Because the realm of VEs is so vast and diverse in application domains and devices, we do not claim that our methodology supports an exhaustive usability evaluation of all VEs. However, the proposed technique is a first attempt at modifying existing usability evaluation methods, and therefore can be used as a launching pad for methodologies to evaluate other aspects of specific VE applications. / Master of Science

A problem solving environment (PSE) provides all computational facilities necessary for solving a target class of problems efficiently. PSEs are used primarily for domain-specific problem-solving in science and engineering and aim to ease the burden of advanced scientific computing. Scientific problem solving, however, often involves the use of legacy resources which are difficult to modify or port, and may be distributed on different machines. Existing PSEs provide little support for solving such problems in a generic framework. This thesis investigates the design of a platform-independent system that enables problem solving using legacy resources without having to modify legacy code. It presents Symphony, an open and extensible Java-based framework for composition and manipulation of distributed legacy resources. Symphony allows users to compose visually a collection of programs and data by specifying data-flow relationships among them and provides a client/server framework for transparently executing the composed application. Additionally, the framework is web-aware and helps integrate web-based resources with legacy resources. It also enables programmers to provide a graphical interface to legacy applications and to write visualization components. Symphony uses Sun Microsystems' JavaBeans component architecture for providing components that represent legacy resources. These components can be customized and composed in any standard JavaBeans builder tool. Executable components communicate with a server, implemented using Java Remote Method Invocation mechanism, for executing remote legacy applications. Symphony enables extensibility by providing abstract components which can be extended by implementing simple interfaces. Beans implemented from the abstract beans can act as data producers, consumers or filters. / Master of Science