A common concern for people using computer databases is becoming "lost" within the complex hierarchy of entries. Most direct manipulation interface design guidelines suggest designers should include a feature for “undoing” user inputs (Smith and Mosier, 1986). In the case of a database, undo translates to backtracking support. The first purpose of this research was to confirm that computer-supported backtracking tools reduce navigation time over manual backtracking. The second purpose was to compare navigation times among a subset of backtracking tools. The third purpose was to determine if users prefer to use one or more backtracking tools significantly more than others. Four backtracking tools were developed by crossing two factors: History (history list vs no history list) and Level (component vs entry). History list indicates the user may view a chronological listing of nodes that have been viewed and directly select a destination node. No history list means the user must backtrack through each visited node with no shortcuts. Component indicates the backtracking tools operate only at the lowest level, or smallest definable node, of the tree-like database structure. Entry means that backtracking occurs at the higher parent node. Thus, multiple components make up an entry . In addition to the four computer backtracking tools, overall navigating and manual backtracking was done using a hierarchical Table of Contents. The tools were evaluated in an experimental, hierarchical, direct-manipulation database. Trials were conducted in the form of a multiple-choice information retrieval task. The independent variables included the backtracking tool (four-computer supported, one-manual) and the backtrack Task Length. The dependent measures included navigation time, the frequency with which the computer tool was used over manual backtracking (Table of Contents), and questionnaire responses. The results of this study provided some of the first solid support for the many guidelines that have been written recommending user recovery, or undo support. Backtracking with any of the four computer-supported tools resulted in a significantly smaller navigation time than manual backtracking using the Table of Contents. Subjects using either of the entry tools had consistent backtracking times across trials regardless of backtrack task length. When provided with a history list, subjects in the entry condition had significantly smaller navigation times than subjects in the component condition. Users did not show any differences between computer tools in rated efficiency, ease of use, or objective preference measures. / Master of Science

A systems engineering life-cycle approach is used to design the Facilities Automated Scheduling Tool (FAST) for the Facilities Branch of the ABC Company. The emphasis of the proposed design is the human factors criteria that are used to optimize the human-computer interface (HCI). The need identified by the Facilities Branch is that the current manual project tracking system takes three weeks to gather the information required to initiate a request for change (RFC). Paperwork is cumbersome, data files are difficult to locate, and the Facilities Specialists are inundated with fragmented reports filed away in cabinets that are taking up what little free space the office has left. Therefore, the requirements for the system are established, options considered, and a recommended design is achieved which will reduce the number of file cabinets by 80%, enable a project to be input into the system in fifteen minutes, and reduce the number of data input specialists from three to one, saving the company time and money. FAST is essential to the Facilities Branch for optimal efficiency and cost-effective performance. Furthermore, many different operators need the system to track their specific projects. Most of these Facilities Specialists are not "regular" computer users, therefore, user-friendliness is of critical importance. Analyzing human factors options and presenting trade-offs is of utmost importance to ensure FAST will be used properly. If the user becomes frustrated with the system, the tool will no longer be useful to the operator or the Facilities Branch. Both the hardware and software configurations of FAST are examined for user-friendliness and efficiency. The ABC Company has a service contract with IBM, where all the hardware equipment is bought. Therefore, an IBM platform is assumed for FAST. However, various screen designs and workstation arrangements are examined in order to produce a safe. comfortable, reliable, and efficient system that will save the ABC Company time and money. / Master of Science

Computer graphics is an important tool for engineering visualization and computer aided design systems. The use of this tool to create graphical user interfaces (GUIs) for engineering applications is growing dramatically owing to the almost real-time response to creative thinking which allows engineers to quickly visualize many potential solutions to a problem. This thesis describes the creation of a GUI for a software system which is capable of predicting the surface temperatures generated at the contact between two sliding bodies. This GUI uses the ISO standard PHIGS for 3D graphics support. The use of PHIGS and the standard programming language C renders this system device-independent and hence, portable. Although PHIGS supports the creation of graphics-based engineering applications, many basic functions required for a GUI (e.g. functions for menus, templates, etc.) need to be created from scratch. During the creation of the GUI described in this thesis, special attention was paid to functions which could be created as re-usable, high-level functions. These functions can be made available to other programmers who wish to create similar GUIs for other engineering applications. The design and creation of these high-level functions and the use of these high-level functions in the creation of the GUI for the surface temperature prediction software are described in this thesis. / Master of Science

The user interface for a proposed alternative emergency service was conceived and designed for a standard touch-tone telephone. The service would allow a user to activate an automated, pre-recorded message containing information to aid emergency responders. The user must only press a few specified keys on the telephone key-pad, avoiding the need for verbal interaction with a dispatcher. The interface was designed in terms of providing the necessary instructions for activation and considering various input strategies and feedback. Icons, written instructions, and voice feedback were employed in the development of a successful and effective interface between the user and the system. Because the system is expected to attract elderly users and families with young children, the performance and attitudes of these two age groups in regard to a system prototype were examined to determine if the interface was suitable. A two and eight second initial system response time were imposed upon users to determine any effect these delays might have on user response time, error rate, and subjective attitudes. Additionally, a secondary task, designed to increase cognitive loading was employed to determine if the system is usable while the user is engaged in a dual-task environment. The dependent variables used to gauge the effects of the manipulated variables include the objective measures of user response time and error rate and subjective questionnaire responses. The results of the study indicate that the elderly adults and young children were able to activate the system successfully. System response time and cognitive loading had no significant effect on user performance or subjective attitudes. Distinct practice effects were observed. Attitude scales indicated satisfaction with the service and its interface. Finally, a significant effect of age was observed on average user response time, with the elderly activating the system quicker than the children. / Master of Science

Much of the hypermedia literature instructs developers to "Use a map to prevent users from becoming lost." However, there is very little empirical evidence that maps are effective. In addition, no one has examined how to design the maps to make them most helpful to the users. This research evaluates both issues for information retrieval tasks with a fairly small hypermedia application (about 175 nodes). This study evaluates the overall effectiveness of maps by comparing the subjects' performance using hypermedia without a map to performance with one of four maps. Then, it reveals the relative effectiveness of the different types of maps by comparing the results of the subjects' performance with four variations of a map. In addition, this research evaluates (1) the effects of the experimental conditions on the subjects' mental models of the application and (2) the effects of the subjects' spatial abilities on their performance with hypermedia. The results reveal that there is generally no difference between the subjects' performance with a map and performance without a map. In addition, users who had to navigate using the links within the application rather than selecting nodes from the map (using a "passive" map) viewed more extra nodes, but spent less time on each node and completed the tasks in less time than those who could select nodes directly from the map (using an "active" map). However, many of the subjects using the passive map would have preferred to use an active map. Also, subjects who always had a map available to them (using a "present" map) performed as well as subjects who had to call up a map to use it (a "called" map). In addition, there is no difference in the accuracy of the subjects' mental models. All the subjects understood the application fairly well. A few of the spatial abilities test results are correlated with performance, and all of significant correlations indicate that higher spatial abilities leads to improved performance with hypermedia. It is believed that the lack of differences among the conditions is due to a number of factors, including the simplicity of the application the subjects used and the tasks they performed. / Master of Science

This thesis presents Taskmaster.2, a graphical environment for interactive task specification, execution and monitoring. Problem solving in the Taskmaster environment can be accomplished with top-down programming, bottom-up programming, or a mixture of the two. The use of top-down programming permits the user to start with a high level task and refine this task into successively lower level subtasks until, at the lowest level, each subtasks represents a software tool. Bottom-up programming is accomplished by beginning with the lowest level subtasks, software tools, and then combining these tools into successively higher level subtasks until, at the highest level, the high level subtask represents the original problem task. These programming methods provide the user with abstraction capabilities. Another abstraction capability within the Taskmaster.2 environment is the network tools. The user creates network tools by selecting several software tools that, combined, provide a certain functionality. These network tools can then be reused in solving other problem tasks. In fact, these tools appear no different to the user than the low level software tools: they are both single indivisible units. Providing complete abstraction capabilities, i.e., mixing programming styles (top-down and bottom-up) and network tools, maintains the consistency of the Taskmaster.2 environment. This makes the environment an easy one to learn, as well as remember. / Master of Science

Since the 1960's an overwhelming amount of in-house and custom engineering software has been written. In the effort to reduce the cost of maintaining existing codes and producing new applications, the recent introduction of the object-oriented design approach has proved successful. At the same time graphical user interfaces are gaining in popularity to improve the usability and versatility of an application. This thesis investigates the application of the object-oriented approach to the design of a graphical user interface for an engineering design application. The development of an object-oriented graphical user interface for the NASA Engine Performance Program, a turbine engine design code is presented. The design of the new object-oriented graphical user interface for extensibility and re-usability is discussed. Design considerations for integration of the interface with procedural and object-oriented versions of the conceptual aircraft design program, ACSYNT, are explained. An existing PHIGS-based object-oriented graphical user interfacing framework is extended and built upon to develop the class structure of the interface. The class organization is presented in commonly used notation and described in detail. / Master of Science

Due to the fastest growing senior population, age-related cognitive impairments, including Alzheimer's disease, are becoming among the most common diseases in the United States. Currently, prevention through delay is considered the best way to tackle Alzheimer's disease and related dementia, as there is no known cure for those diseases. Early detection is crucial, in that screening individuals with Mild Cognitive Impairment may delay its onset and progression. For my dissertation work, I investigate how computing technologies can help medical practitioners detect and monitor cognitive impairment due to dementia, and I develop a computerized sketch-based screening tool. In this dissertation, I present the design, implementation, and evaluation of the ClockMe System, a computerized Clock Drawing Test. The traditional Clock Drawing Test (CDT) is a rapid and reliable instrument for the early detection of cognitive dysfunction. Neurologists often notice missing or extra numbers in the clock drawings of people with cognitive impairments and use scoring criteria to make a diagnosis and treatment plan. The ClockMe System includes two different applications - (1) the ClockReader for the patients who take the Clock Drawing Test and (2) the ClockAnalyzer for clinicians who use the CDT results to make a diagnosis or to monitor patients. The contributions of this research are (1) the creation of a computerized screening tool to help clinicians identify cognitive impairment through a more accessible and quick-and-easy screening process; (2) the delivery of computer-collected novel behavioral data, which may offer new insights and a new understanding of a patient's cognition; (3) an in-depth understanding of different stakeholders and the identification of their common user needs and desires within a complicated healthcare workflow system; and (4) the triangulation of multiple data collection methods such as ethnographical observations, interviews, focus group meetings, and quantitative data from a user survey in a real-world deployment study.

The Unified Modeling Language (UML) is the successor to the wave of object-oriented analysis and design (OOA&D) methods that appeared in the late '80s and early '90s. The class diagram is one of the most useful diagrams in UML. The class diagram technique has become truly central within object-oriented methods.

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy