Browsing by Subject "Industrial and systems engineering"

Now showing 1 - 3 of 3
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    Capacity management in health care delivery systems
    (2012-08) Wang, Wen-Ya
    This dissertation contains three capacity management problems in health care delivery systems. In particular, Chapter 2 evaluates a panel design problem regarding how clinics may wish to best allocate a pool of heterogeneous patients (i.e. non-acute and acute patients) into physician panels. The analytical results show that neither specialization (i.e. each panel contains patients that are as homogeneous as possible) or equal assignment (i.e. identical panels with same types of patient mix) is a dominant patient allocation strategy. The results also show that equal assignment strategy works better when acute demand is relatively low or high as compared to the capacity, and specialization works better when acute demand is moderate. This chapter serves to highlight the impact of patient composition on the performance of a clinic profile. Chapter 3 investigates how clinics may learn and utilize patients' preference information through an existing web-based interface in appointment booking decisions. Analytical results leading to a partial characterization of an optimal booking policy are presented. Examples show that heuristic decision rules, based on this characterization, perform well and reveal insights about trade-offs among a variety of performance metrics such as expected revenue, patient-PCP match rate, number of patients served, and capacity spoilage rate. Chapter 4 focuses on identifying observable predictors of nurse absenteeism and incorporates these factors into staffing decisions. The analysis highlights the importance of paying attention to unit-level factors and absentee-rate heterogeneity among individual nurses. The data-based investigation confirms that nurses' absence history is a good predictor of their future absences. This result is used as the nurse absenteeism assumption in the model-based investigation that evaluates how to assign nurses to identical nursing units when nurses' absentee rates are heterogeneous. We propose and test several easy-to-use heuristics to identify near optimal staffing strategies for inpatient units.
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    Development and evaluation of gesture rich collaborative drawing tools.
    (2011-05) Cornelius, Caroline Joyce
    Non-verbal gestures are a rich source of communication, especially in tasks involving spatial concepts. When teams working on a common task are separated geographically, the information in gestures is lost. However, there are many ways to convey gestures over distance to make up for this loss. In a simple shared collaborative software tool, cursors can be used to exchange simple gestures. It is also possible to increase the richness of information exchanged by sharing hand images of the participants to each other. One of the questions this thesis aims to answer is whether hand images are necessary at all or if a simple cursor would be sufficient. This thesis describes the development and evaluation of software for collaborative drawing, in which two users in multiple locations can connect and draw using a simple drawing tool. They will share the same drawing screen but have separate cursors. A table top touch screen was set up for the experiment. The evaluation of the software was based on comparing collaboration for a spatial design/drawing when users collaborate by three different methods: face-to-face, virtual sketching, and virtual sketching with the hand gestures of the virtual collaborators projected on the drawing surface. Two tools were created for this work- one for virtual sketching and the other for virtual sketching that enables sharing of hand gestures. The results indicated that users’ performance in the face-to-face collaboration was almost identical to virtual collaboration with hand images. Virtual collaboration without hand images was significantly more difficult. These results suggest that rich hand gestures conveyed with the hands in face-to-face settings is important in joint spatial tasks; their loss reduces effectiveness in virtual collaboration on such tasks. However, the addition of hand images projected on a joint work surface can restore effectiveness to levels similar to that of face-to-face collaboration. A robust setup of the software enabling transfer of rich hand gestures could be used where in getting all team members to a single geographical location for a meeting might be time consuming, expensively or simply impossible.
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    Usability evaluation of fuel gauges for hybrid electric vehicles
    (2014-12) Bhargava, Esha
    This thesis describes a usability study designed to increase an automotive designer's understanding of how to design effective dual-fuel gauges for hybrid vehicles. Hybrid Electric Vehicles (HEVs) aim at reducing dependency on gasoline. While gasoline has one primary source, which is non-renewable, electricity comes from renewable as well as non-renewable sources of energy. As we begin to generate electricity more efficiently from newer power plants that are built using renewable energy, it is important that drivers of HEVs begin to reduce their dependency on gasoline and rely more on electricity for operating their vehicles. Hybrid fuel gauges have a role to play in the overall user experience and adoption of HEVs. When purchasing a car, people take into consideration how the instrument panel looks and how understandable it is (Green, 1984). Therefore, it is important that these gauges are effective in providing information on fuel levels so that it can be read quickly and accurately.The goal of this work was to identify a class of gauges that support quick and accurate reading so that the driver can understand when to recharge the electric battery or refill the gas tank for efficient trip planning. A set of thirty-three hybrid gauge designs created by designers at General Motors was provided to the University of Minnesota team. The UMN team created four new gauge designs that were different from the ones created by the General Motors. These were reduced to a set of nine gauges by the process of heuristic evaluation. A two-part usability study was conducted with sixty drivers. In the first part, drivers participated in a timed comprehension task in which they were made to view certain gauges and answer questions on them. This was followed by a subjective questionnaire in which participants were asked about their preferences for various gauges.Vertically oriented bar gauges were found to be most effective. They elicited the highest accuracy rates and lowest response times compared to horizontally oriented bar gauges and circular gauges. Participants were able to process information in relative form (expressed in graphical or pictorial form) more easily and accurately than information in absolute form (expressed in numeric form). Familiar types of gauges, which appeal to participants, do not always contribute to better performance. Introducing new types of gauges requires more upfront marketing of their benefits (such as higher reading accuracy and speed).A set of recommendations has been created for automotive designers on how to create effective hybrid fuel gauges. These recommendations are important in driving standardization of hybrid fuel gauges to help deliver a consistent user experience and to minimize confusion and user frustration. These gauges encourage fuel-efficient behavior by helping drivers reduce their dependency on gasoline, thereby reducing pollution from carbon dioxide emissions and ultimately resulting in a cleaner environment.