Thesis (M.Diploma in Electrical Engineering)--Cape Technikon, 1992 / This thesis describes how an adaptor board was developed to enable serial devices, such as modems and serial printers operating on RS-232 signals, to be used in conjunction with the MINITEL terminal. Furthermore it enables parallel Centronix interfaces to be Used in conjunction with the MINITEL terminal. The revolutionary 87C751 microprocessor was fully researched, and implemented in the project. Two marketable products emerged during the course of the project: • 1. The 8031-processor solution 2. The 87C751-processor solution

abstract: Achievement of many long-term goals requires sustained practice over long durations. Examples include goals related to areas of high personal and societal benefit, such as physical fitness, which requires a practice of frequent exercise; self-education, which requires a practice of frequent study; or personal productivity, which requires a practice of performing work. Maintaining these practices can be difficult, because even though obvious benefits come with achieving these goals, an individual's willpower may not always be sufficient to sustain the required effort. This dissertation advocates addressing this problem by designing novel interfaces that provide people with new practices that are fun and enjoyable, thereby reducing the need for users to draw upon willpower when pursuing these long-term goals. To draw volitional usage, these practice-oriented interfaces can integrate key characteristics of existing activities, such as music-making and other hobbies, that are already known to draw voluntary participation over long durations. This dissertation makes several key contributions to provide designers with the necessary tools to create practice-oriented interfaces. First, it consolidates and synthesizes key ideas from fields such as activity theory, self-determination theory, HCI design, and serious leisure. It also provides a new conceptual framework consisting of heuristics for designing systems that draw new users, plus heuristics for making systems that will continue drawing usage from existing users over time. These heuristics serve as a collection of useful ideas to consider when analyzing or designing systems, and this dissertation postulates that if designers build these characteristics into their products, the resulting systems will draw more volitional usage. To demonstrate the framework's usefulness as an analytical tool, it is applied as a set of analytical lenses upon three previously-existing experiential media systems. To demonstrate its usefulness as a design tool, the framework is used as a guide in the development of an experiential media system called pdMusic. This system is installed at public events for user studies, and the study results provide qualitative support for many framework heuristics. Lastly, this dissertation makes recommendations to scholars and designers on potential future ways to examine the topic of volitional usage. / Dissertation/Thesis / Ph.D. Media Arts and Sciences 2013

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This thesis introduces a novel Eulerian-on-Lagrangian (EoL) approach for simulating cloth. This approach allows for the simulation of traditionally difficult cloth scenarios, such as draping and sliding cloth over sharp features like the edge of a table. A traditional Lagrangian approach models a cloth as a series of connected nodes. These nodes are free to move in 3d space, but have difficulty with sliding over hard edges. The cloth cannot always bend smoothly around these edges, as motion can only occur at existing nodes. An EoL approach adds additional flexibility to a Lagrangian approach by constructing special Eulerian on Lagrangian nodes (EoL Nodes), where cloth material can pass through a fixed point. On contact with the edge of a box, EoL nodes are introduced directly on the edge. These nodes allow the cloth to bend exactly at the edge, and pass smoothly over the area while sliding. Using this ‘Eulerian-on-Lagrangian’ discretization, a set of rules for introducing and constraining EoL Nodes, and an adaptive remesher, This simulator allows cloth to move in a sliding motion over sharp edges. The current implementation is limited to cloth collision with static boxes, but the method presented can be expanded to include contact with more complicated meshes and dynamic rigid bodies.

With the emergence of big data, scientific data analysis and visualization (DAV) tools are critical components of the data science software ecosystem; the usability of these tools is becoming extremely important to facilitate next-generation scientific discoveries. JupyterLab has been considered as one of the best polyglot, web-based, open-source data science tools. As the next phase of extensible interface for the classic iPython Notebooks, this tool supports interactive data science and scientific computing across multiple programming languages with great performances. Despite these advantages, previous heuristics evaluation studies have shown that JupyterLab has some significant flaws in the data visualization side. The current DAV system in JupyterLab heavily relies on users’ understanding and familiarity with certain visualization libraries, and doesn’t support the golden visual-information-seeking mantra of “overview first, zoom and filter, then details-on-demand”. These limitations often lead to a workflow bottleneck at the start of a project. In this thesis, we present ‘JupyterLab_Voyager’, an extension for JupyterLab that provides a graphical user interface (GUI) for data visualization operations and couples faceted browsing with visualization recommendation to support exploration of multivariate, tabular data, as a solution to improve the usability of the DAV system. The new plugin works with various types of datasets in the JupyterLab ecosystem; using the plugin you can perform a high-level graphical analysis of fields within your dataset sans coding without leaving the JupyterLab environment. It helps analysts learn about the dataset and engage in both open-ended exploration and target specific answers from the dataset. User testings and evaluations demonstrated that this implementation has good usability and significantly improves the DAV system in JupyterLab.

With the advent of modern graphics and computing hardware and cheaper sensor and display technologies, virtual reality is becoming increasingly popular in the fields of gaming, therapy, training and visualization. Earlier attempts at popularizing VR technology were plagued by issues of cost, portability and marketability to the general public. Modern screen technologies make it possible to produce cheap, light head-mounted displays (HMDs) like the Oculus Rift, and modern GPUs make it possible to create and deliver a seamless real-time 3D experience to the user. 3D sensing has found an application in virtual and augmented reality as well, allowing for a higher level of interaction between the real and the simulated. There are still issues that persist, however. Many modern graphics/game engines still do not provide developers with an intuitive or adaptable interface to incorporate these new technologies. Those that do, tend to think of VR as a novelty afterthought, and even then only provide tailor-made extensions for specific hardware. The goal of this paper is to design and implement a functional, general-purpose VR engine using abstract interfaces for much of the hardware components involved to allow for easy extensibility for the developer.

As technology use increases in the world and inundates everyday life, the visual aspect of technology or computer graphics becomes increasingly important. This thesis presents a system for the automatic generation of virtual camera paths for fly-throughs of a digital scene. The sample scene used in this work is an underwater setting featuring a shipwreck model with other virtual underwater elements such as rocks, bubbles and caustics. The digital shipwreck model was reconstructed from an actual World War II shipwreck, resting off the coast of Malta. Video and sonar scans from an autonomous underwater vehicle were used in a photogrammetry pipeline to create the model. This thesis presents an algorithm to automatically generate virtual camera paths using a robotics motion planning algorithm, specifically the probabilistic roadmap. This algorithm uses a rapidly-exploring random tree to quickly cover a space and generate small maps with good coverage. For this work, the camera pitch and height along a specified path were automatically generated using cinematographic and geometric principles. These principles were used to evaluate potential viewpoints and influence whether or not a view is used in the final path. A computational evaluation of ‘the rule of thirds’ and evaluation of the model normals relative to the camera viewpoint are used to represent cinematography and geometry principles. In addition to the system that automatically generates virtual camera paths, a user study is presented which evaluates ten different videos produced via camera paths with this system. The videos were created using different viewpoint evaluation methods and different path generation characteristics. The user study indicates that users prefer paths generated by our system over flat and randomly generated paths. Specifically, users prefer paths generated using the computational evaluation of the rule of thirds and paths that show the wreck from a large variety of angles but without too much camera undulation.

An index in a database system interacts with many of the software modules in the system. For systems supporting a wide range of index structures, interfacing the index code with the rest of the system poses a great problem. The problems are an order of magnitude more for adding new access methods to the system. These problems could be reduced manifold if common interfaces could be specified for different access methods. It would be even better, if these interfaces could be made database-system independent. This thesis addresses the problem of defining generic index interfaces for access methods in database systems. It concentrates on two specific issues: First, specification of a complete set of abstract interfaces that would work for all access methods and for all database systems. Second, optimized query processing for all data types including userdefined data types. An access method in a database system can be considered to be made up of three specific parts: Upper interfaces, lower interfaces, and type interfaces. An access method interacts with a database system through its upper interfaces, lower interfaces and type interfaces. Upper interfaces consist of the functions an index provides to a database system. Lower interfaces are the database-system dependent software modules an index has to interact with, to accomplish any system related functions. Type interfaces consist of the set of functions an index uses, which interpret the data type. These three parts together characterize an access method in a database system. This splitting of an access method makes it possible to define generic interfaces. In this thesis, we will discuss each of these three different interfaces in detail, identify functionalities and design clear interfaces. The design of these interfaces promote development of type-independent and database-system independent access methods.

Intracortical brain-computer interfaces (BCIs) provide the means to do something extraordinary: restore movement to patients with paralysis or amputated limbs. Realizing this potential requires the development of decode algorithms capable of accurately translating measurements of neural activity, in real time, into appropriate time-varying commands for an external device (e.g. prosthetic limb). This problem is fundamentally interdisciplinary, drawing on tools and insights from engineering, neuroscience, statistics, and computer science, among others. Decode algorithms that have been favored historically tend to be computationally efficient, but perform suboptimally, likely because their assumptions fail to fully and accurately capture the complexity in neural population responses. Recent work harnessing the power of contemporary machine learning methods has raised the performance bar, yet these methods can be computationally demanding and it is unclear what properties of neural and/or behavioral data they exploit. In this dissertation, we characterize properties of motor-cortex population geometry and let these properties dictate decoder design, resulting in methods that perform very well, yet retain the benefits of simpler methods. We use this approach to develop a closed-loop navigation BCI, and to design a highly accurate, general, and interpretable decoder. The properties described in this dissertation have implications for any BCI. By designing decoders to explicitly respect (and leverage) these properties, we can construct powerful yet practical BCIs that better meet the needs of patients.

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