Formation Flight Control for Aerial Refueling

A controller is designed for an aircraft to autonomously fly formation during aerial refueling. Requirements for a refueling autopilot are stated. A six-degree-of-freedom model is developed for an F-16 lead aircraft and a Learjet LJ-25 wing aircraft. Bare airframe stability of both aircraft is investigated, and stability augmentation is performed. A Matlab Simulink® simulation is built to reproduce the sensor inputs that will be available to the wing aircraft in flight, including disturbances. Control frames are investigated to determine the optimum presentation of the error vector for control during the task of air refueling. Control laws are developed from the initial premise of proportional-plus-integral (PI) control on position error only, and made more complex until desired performance is achieved. Tanker flight profiles are designed for the lead aircraft, and simulations are accomplished to estimate controller performance. Stability and robustness are investigated through the addition of noise, turbulence, and time delays while exploring the capability limits during increasingly aggressive profiles. Modifications for flight test are described, and flight test results are reviewed from seven formation flights of a USAF C-12 and a Learjet LJ-25 under fully autonomous control in an operationally representative refueling environment. Actual controller performance is analyzed and compared to predictions, and suggestions are made for future controllers

Stochastic Real-time Optimal Control: A Pseudospectral Approach for Bearing-Only Trajectory Optimization

A method is presented to couple and solve the optimal control and the optimal estimation problems simultaneously, allowing systems with bearing-only sensors to maneuver to obtain observability for relative navigation without unnecessarily detracting from a primary mission. A fundamentally new approach to trajectory optimization and the dual control problem is developed, constraining polynomial approximations of the Fisher Information Matrix to provide an information gradient and allow prescription of the level of future estimation certainty required for mission accomplishment. Disturbances, modeling deficiencies, and corrupted measurements are addressed with recursive updating of the target estimate with an Unscented Kalman Filter and the optimal path with Radau pseudospectral collocation methods and sequential quadratic programming. The basic real-time optimal control (RTOC) structure is investigated, specifically addressing limitations of current techniques in this area that lose error integration. The resulting guidance method can be applied to any bearing-only system, such as submarines using passive sonar, anti-radiation missiles, or small UAVs seeking to land on power lines for energy harvesting. Methods and tools required for implementation are developed, including variable calculation timing and tip-tail blending for potential discontinuities. Validation is accomplished with simulation and flight test, autonomously landing a quadrotor helicopter on a wire

Stochastic Real-time Optimal Control for Bearing-only Trajectory Planning

A method is presented to simultaneously solve the optimal control problem and the optimal estimation problem for a bearing-only sensor. For bearing-only systems that require a minimum level of certainty in position relative to a source for mission accomplishment, some amount of maneuver is required to measure range. Traditional methods of trajectory optimization and optimal estimation minimize an information metric. This paper proposes constraining the final value of the information states with known time propagation dynamics relative to a given trajectory which allows for attainment of the required level of information with minimal deviation from a general performance index that can be tailored to a specific vehicle. The proposed method does not suffer from compression of the information metric into a scalar, and provides a route that will attain a particular target estimate quality while maneuvering to a desired relative point or set. An algorithm is created to apply the method in real-time, iteratively estimating target position with an Unscented Kalman Filter and updating the trajectory with an efficient pseudospectral method. Methods and tools required for hardware implementation are presented that apply to any real-time optimal control (RTOC) system. The algorithm is validated with both simulation and flight test, autonomously landing a quadrotor on a wire

Educational Technology Research Past and Present: Balancing Rigor and Relevance to Impact School Learning

Today, the exponential growth of technology usage in education, via such applications of distance education, Internet access, simulations, and educational games, has raised substantially the focus and importance of educational technology research. In this paper, we examine the past and present research trends, with emphasis on the role and contribution of research evidence for informing instructional practices and policies to improve learning in schools. Specific topics addressed include: (a) varied conceptions of “effective” technology uses in classroom instruction as topics for research, (b) historical trends in research approaches and topics of inquiry; (c) alternative research designs for balancing internal (rigor) and external (relevance) validity; and (d) suggested directions for future research. Attention is devoted to describing varied experimental designs as options for achieving appropriate rigor and relevance of research evidence, and using mixed-methods research for investigating and understanding technology applications in complex real-life settings

Applied Plasma Research

Contains reports on two research projects.National Science Foundation (Grant GK-28282X1)National Science Foundation (Grant GK-33843

Neurofeedback Within the Scope of Occupational Therapy With Clients with Substance Use Disorder: A Scoping Review

Substance use disorder (SUD) is a problematic pattern of use of a substance or substances, leading to impairments to health, social function, and control of a substance. This negatively affects everyday activities of daily living, and occupation performance that causes a disruption to physical, mental, and social health. Now, Neurofeedback is a noninvasive biotherapy that uses audio or video feedback to reinforce healthy brain function. This type of intervention usually works by having a patient listen to music and putting electrodes on a patient’s head that pick up negative or positive brain activity or waves. And if the negative activity is identified there were be a skip in the music. Over time, the negative feedback received by the brain will train the brain to subconsciously make healthy connections. Neurofeedback literature address different types of aspects that impact individual\u27s life. This includes cognition attention in memory, learning, anxiety, depression, sleep quality, and many more psychological aspects With that being said OTs help people construct and destruct New or pre-existing habits and roles that would lead them throughout recovery. And Neurofeedback could be a beneficial intervention or conjunction intervention. However, there is no systematic understanding of how neuro-feedback therapy can be used in the substance-use population within the scope of the OT practice. This leads me to the problem which is the use of neural feedback, therapy in clients with substance use disorder has not been systematically reviewed to identify its use within the scope of OT practice, leaving it difficult for OT practitioners to integrate neurofeedback into OT for clients with substance use disorders. So the purpose of my capstone project was to conduct a scoping review of the literature to identify how Neurofeedback is utilized with clients with substance use disorder that is within the scope of OT practice.https://soar.usa.edu/otdcapstonessummer2023/1049/thumbnail.jp

Modeling and experimental results for condensing supercritical CO2 power cycles.

This Sandia supported research project evaluated the potential improvement that 'condensing' supercritical carbon dioxide (S-CO{sub 2}) power cycles can have on the efficiency of Light Water Reactors (LWR). The analytical portion of research project identified that a S-CO{sub 2} 'condensing' re-compression power cycle with multiple stages of reheat can increase LWR power conversion efficiency from 33-34% to 37-39%. The experimental portion of the project used Sandia's S-CO{sub 2} research loop to show that the as designed radial compressor could 'pump' liquid CO{sub 2} and that the gas-cooler's could 'condense' CO{sub 2} even though both of these S-CO{sub 2} components were designed to operate on vapor phase S-CO{sub 2} near the critical point. There is potentially very high value to this research as it opens the possibility of increasing LWR power cycle efficiency, above the 33-34% range, while lowering the capital cost of the power plant because of the small size of the S-CO{sub 2} power system. In addition it provides a way to incrementally build advanced LWRs that are optimally designed to couple to S-CO{sub 2} power conversion systems to increase the power cycle efficiency to near 40%