Dissertation Defense Announcements

Autonomous vehicles have gained huge interest across private industry, academia, government, and the public because they promise higher road efficiency, improved safety, better energy consumption, and improved emissions. However, the widespread adoption of autonomous vehicle technology will likely take place over several years (if not decades) as the technology becomes more widely accepted by the general public and more cost-effective. Therefore, there will be a long period of time when we have both autonomous and human-driven vehicles sharing the same road and it is essential to develop traffic management strategies that take the uncertainty associated with the heterogeneity in the traffic networks into account. Furthermore, it is crucial to understand the extent to which these control strategies improve the performance of the traffic network.
This research aims to develop, enhance, and validate hierarchical infrastructure-based control framework designs for improving the mobility of large-scale heterogeneous traffic networks. In this work, heterogeneity is defined as a multi-vehicle traffic network consisting of Human-Driven Vehicles (HDVs) and Autonomous Vehicles (AVs), distinguished by their operational characteristics and controllability. To capture the realistic nature of large-scale heterogeneous traffic networks, we adopt the heterogeneous (multi-class) METANET model wherein the density and velocity dynamics of each vehicle class in each cell are described mathematically.
Moreover, in this research, we propose a hierarchical distributed infrastructure-based control framework to manage large-scale heterogeneous traffic networks. At the lower-level, we employed the Distributed Filtered Feedback Linearization (D-FFL) controller which only requires limited information from the plant model. The purpose of this controller is to track the desired density of each vehicle class in the target cells which is set by the upper-level controller. D-FFL tracks the reference density by controlling the suggested velocity of vehicles in the target cell and its upstream cell. At the upper-level, in our initial design, a Distributed Extremum-Seeking (D-ES) controller is designed and implemented to find the optimal operating densities of each vehicle class in the target cells over time. Gradient-based D-ES is a model-free, real-time adaptive control algorithm that is useful for adapting control parameters to unknown system dynamics and unknown mappings from control parameters to an objective function. To improve the performance of the designed hierarchical controller and reduce the convergence time, we designed and implemented Lyapunov-based Switch Newton Extremum Seeking (LSNES) at the upper level of the hierarchy to feed the optimal density of each vehicle class in the target cells to the lower-level controller. One of the key distinctions between the Newton algorithm and the gradient algorithm is that the convergence of the former is not solely contingent on the second derivative (Hessian) of the cost map and it is user-assignable.
Finally, we established a MATLAB-VISSIM COM interface that allows closed-loop control of a simulated traffic scenario in PTV-VISSIM to test and validate the effectiveness of the distributed control approaches in large-scale traffic networks. The simulation results show that our control framework design can effectively reduce congestion and prevent congestion back-propagation during peak hours in large-scale traffic networks.

Background
Corneal abrasions (CA) are one of the most common anesthesia-related adverse events. There is limited evidence about the effect of virtual education on anesthesia providers’ knowledge regarding CA prevention.

Purpose
The purpose of this study project was to assess if a web based educational module effectively improved anesthesia providers’ awareness of evidence-based preventative measures of CA at a One Day Surgery Center.

Method
This was a quasi-experimental pretest-posttest study design. All participants completed a questionnaire regarding the knowledge on corneal abrasion prevention before and after the educational module. A student T-test was used to compare the differences in pre- and post-education knowledge scores.

Results
Among 26 participants, 15.4% were anesthesiologists, and 84.6% were CRNA. There was a significant pretest-posttest difference on the total knowledge score (6.54±1.14 vs. 8.55± 1.53, p< .001). Overall, the average number of correct answers increased from 6.54 ± 1.14 to 8.55 ± 1.53 ( t = 5.74, p < .001)

Conclusion
The web-based educational module was effectively to enhance anesthesia providers’ knowledge in preventing surgical induced CA. The finding may add evidence on developing the effective guideline and standardizing provider education in CA prevention.

The purpose of this quality improvement project was to identify trends in the intraoperative dosing of dexamethasone in type II diabetic patients undergoing genitourinary procedures at a full-service community hospital and to determine impact of dosage level on postoperative glycemic response compared to preoperative blood glucose levels. Dexamethasone is a corticosteroid that has many dose-dependent benefits when administered perioperatively to surgical patients. It is often withheld in the type II diabetic population out of concern for effects on postoperative glycemic control due to the side effect of hyperglycemia.

The method of this quality improvement project consisted of a retrospective chart review of patients with type II diabetes undergoing genitourinary procedures. Data inclusion criteria included patients who: are type II diabetics, had procedures that lasted less than four hours, had a documented preoperative hemoglobin A1C reading within the last twelve months ranging from 6.5-8.9%, are non-pregnant, are not taking oral steroidal medications, and had an ASA classification of I, II, or III.

Forty-nine charts were reviewed and overall there was no significant change in blood glucose in the postoperative period (t = 0.92, p = 0.361). The dose of dexamethasone (4, 8, or 10 mg) had no effect on the change in blood glucose levels (t =-1.14, p = 0.263). Additionally, changes in blood glucose were not found to be associated with age, HbA1C, or ASA status.

Dexamethasone administration for patients undergoing genitourinary procedures had no significant impact on blood glucose levels in the postoperative period. These findings may be a result of the shorter length of surgery, in that all 49 charts in this sample consisted of different cystoscopy procedures and had an average surgery length of 66 minutes. Further study is needed to help facilitate anesthesia provider’s decision-making for dexamethasone dosing in type II diabetics.

Background: Patients with limited English proficiency (LEP) are facing significant communication challenges in peri-operative settings, spanning from understanding anesthesia-related information to obtaining informed consent. These language-based obstacles lead to decreased quality of care, lower patient satisfaction, and a heightened risk of adverse healthcare outcomes. The purpose of this study is to investigate if a web-based educational program can increase the anesthesia providers’ awareness of resources, policies, and procedures available for LEP patients. Methods: This quantitative, quasi-experimental project uses a pretest-posttest design sampling from a level II healthcare facility in Charlotte, NC. Results: Twenty-six individuals participated in this study. There was significant pretest-posttest difference on question 2 (language service resources) (χ2(1) = 7.24, p = .007); question 4 (language service procedure) (χ2(1) = 16.50, p < .001); question 5 (policy location) (χ2(1) = 10.00, p = .002); and question 7 (resource location) (χ2(1) = 28.40, p < .001). The average number of correct answers significantly increased from 3.77 ± 1.34 to 6.15 ± 0.46 (t = 8.58, p < .001). Conclusion: The result of this data serves as evidence that a short, simple education module can profoundly impact the anesthesia provider’s understanding of resources and policies surrounding language communication barriers. Future projects should emphasize the importance of bilingual teammates avoiding obtaining pre-operative consent without the presence of a certified interpreter.