Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Actuators (1)
- Aerodynamic (1)
- Anti-slosh device (1)
- Atmospheric physics (1)
- Charging) (1)
-
- Control applications (1)
- Control design (1)
- Couplings (1)
- Distribution of fuel (1)
- Estimation (1)
- FMPU (1)
- Floating Potential Measurement Unit (1)
- In-tank baffles (1)
- International Space Station (1)
- Ionosphere (Instruments and techniques) – Space plasma physics (Numerical simulation studies (1)
- Langmuir probe (1)
- Motion of fuel (1)
- Numerical models (1)
- Numerical simulation (1)
- Observers for nonlinear systems (1)
- Photoelectrons (1)
- Planetary ambipolar electric fields (1)
- Plasma (1)
- Shock (1)
- Shock loading (1)
- Shock waves (1)
- Spacecraft sheaths (1)
- Stabilising vehicle bodies (1)
- Stability analysis (1)
- Uncertainty (1)
Articles 1 - 8 of 8
Full-Text Articles in Physics
Rocket Measurements Of Electron Energy Spectra From Earth’S Photoelectron Production Layer, Aroh Barjatya, Shantanab Debchoudhury, Glyn A. Collinson, Alex Glocer, Dennis Chornay, Et Al.
Rocket Measurements Of Electron Energy Spectra From Earth’S Photoelectron Production Layer, Aroh Barjatya, Shantanab Debchoudhury, Glyn A. Collinson, Alex Glocer, Dennis Chornay, Et Al.
Publications
Photoelectrons are crucial to atmospheric physics. They heat the atmosphere, strengthen 28 planetary ambipolar electric fields, and enhance the outflow of ions to space. However, 29 there exist only a handful of measurements of their energy spectrum near the peak of 30 photoproduction. We present calibrated energy spectra of pristine photoelectrons at their 31 source by a prototype Dual Electrostatic Analyzer (DESA) instrument flown on July 11 32 2021 aboard the Dynamo-2 sounding rocket (NASA № 36.357). Photopeaks arising from 33 30.4nm He-II spectral line were observed throughout the flight above 120km. DESA also 34 successfully resolved the rarely observed …
Reduced-Order Dynamic Modeling And Robust Nonlinear Control Of Fluid Flow Velocity Fields, Anu Kossery Jayaprakash, William Mackunis, Vladimir Golubev, Oksana Stalnov
Reduced-Order Dynamic Modeling And Robust Nonlinear Control Of Fluid Flow Velocity Fields, Anu Kossery Jayaprakash, William Mackunis, Vladimir Golubev, Oksana Stalnov
Publications
A robust nonlinear control method is developed for fluid flow velocity tracking, which formally addresses the inherent challenges in practical implementation of closed-loop active flow control systems. A key challenge being addressed here is flow control design to compensate for model parameter variations that can arise from actuator perturbations. The control design is based on a detailed reduced-order model of the actuated flow dynamics, which is rigorously derived to incorporate the inherent time-varying uncertainty in the both the model parameters and the actuator dynamics. To the best of the authors’ knowledge, this is the first robust nonlinear closed-loop active flow …
Finite-Time State Estimation For An Inverted Pendulum Under Input-Multiplicative Uncertainty, Sergey V. Drakunov, William Mackunis, Anu Kossery Jayaprakash, Krishna Bhavithavya Kidambi, Mahmut Reyhanoglu
Finite-Time State Estimation For An Inverted Pendulum Under Input-Multiplicative Uncertainty, Sergey V. Drakunov, William Mackunis, Anu Kossery Jayaprakash, Krishna Bhavithavya Kidambi, Mahmut Reyhanoglu
Publications
A sliding mode observer is presented, which is rigorously proven to achieve finite-time state estimation of a dual-parallel underactuated (i.e., single-input multi-output) cart inverted pendulum system in the presence of parametric uncertainty. A salient feature of the proposed sliding mode observer design is that a rigorous analysis is provided, which proves finite-time estimation of the complete system state in the presence of input-multiplicative parametric uncertainty. The performance of the proposed observer design is demonstrated through numerical case studies using both sliding mode control (SMC)- and linear quadratic regulator (LQR)-based closed-loop control systems. The main contribution presented here is the rigorous …
Floating Active Baffles, System And Method Of Slosh Damping Comprising The Same, Dae Won Kim, Rudy L. Baum, Vijay Santhanam, Balaji Sivasubramanian, Sathya Gangadharan
Floating Active Baffles, System And Method Of Slosh Damping Comprising The Same, Dae Won Kim, Rudy L. Baum, Vijay Santhanam, Balaji Sivasubramanian, Sathya Gangadharan
Publications
This disclosure provides a system for damping slosh of a liquid within a tank, a baffle for use in the system, and a method of damping slosh using the system. The system includes a plurality of baffles. Each baffle has a body configured to substantially float upon the liquid. Each baffle also has an activation material received along at least a portion of the body. The activation material is magnetically reactive provided in a quantity sufficient to enable the body to be manipulated in the presence of a magnetic field (M). The system further includes an actuator configured to provide …
Optimizing Jets For Wake Control Of Ground Vehicles, Domenic Barsotti, Sandra Boetcher
Optimizing Jets For Wake Control Of Ground Vehicles, Domenic Barsotti, Sandra Boetcher
Publications
A system of wake control for a ground vehicle to help promote increased fuel efficiencies of the ground vehicle by modifying an air flow wake generated during the movement of the vehicle in a forward direction. The system includes at least one slot jet configured to be located along a rear profile portion of the ground vehicle. The at least one slot jet is configured to provide a continuous flow of air at a non-zero velocity when the ground vehicle is moving in a forward direction, the non-zero velocity being at least partially directed in a rearward direction with an …
Payload Charging Events In The Mesosphere And Their Impact On Langmuir Type Electric Probes, T. A. Bekkeng, Aroh Barjatya, U. P. Hoppe, M. Friedrich
Payload Charging Events In The Mesosphere And Their Impact On Langmuir Type Electric Probes, T. A. Bekkeng, Aroh Barjatya, U. P. Hoppe, M. Friedrich
Publications
Three sounding rockets were launched from Andøya Rocket Range in the ECOMA campaign in December 2010. The aim was to study the evolution of meteoric smoke particles during a major meteor shower. Of the various instruments onboard the rocket payload, this paper presents the data from a multi-Needle Langmuir Probe (m-NLP) and a charged dust detector. The payload floating potential, as observed using the m-NLP instrument, shows charging events on two of the three flights. These charging events cannot be explained using a simple charging model, and have implications towards the use of fixed bias Langmuir probes on sounding rockets …
Strain Rate And Orientation Dependencies Of The Strength Of Single Crystalline Copper Under Compression, Virginie Dupont, Timothy C. Germann
Strain Rate And Orientation Dependencies Of The Strength Of Single Crystalline Copper Under Compression, Virginie Dupont, Timothy C. Germann
Aerospace Engineering - Daytona Beach
Molecular dynamics (MD) simulations are used to model the compression under uniaxial strain of copper single crystals of different orientations at various temperatures and strain rates. Uniaxial strain is used because of the close resemblance of the resulting stress state with the one behind a shock front, while allowing a control of parameters such as strain rate and temperature to better understand the behavior under complex dynamic shock conditions. Our simulations show that for most orientations, the yield strength of the sample is increased with increasing strain rate. This yield strength is also dependent on the orientation of the sample, …
Invited Article: Data Analysis Of The Floating Potential Measurement Unit Aboard The International Space Station, Aroh Barjatya, Charles M. Swenson, Donald C. Thompson, Kenneth H. Wright
Invited Article: Data Analysis Of The Floating Potential Measurement Unit Aboard The International Space Station, Aroh Barjatya, Charles M. Swenson, Donald C. Thompson, Kenneth H. Wright
Publications
We present data from the Floating Potential Measurement Unit (FPMU) that is deployed on the starboard truss of the International Space Station. The FPMU is a suite of instruments capable of redundant measurements of various plasma parameters. The instrument suite consists of a floating potential probe, a wide-sweeping spherical Langmuir probe, a narrow-sweeping cylindrical Langmuir probe, and a plasma impedance probe. This paper gives a brief overview of the instrumentation and the received data quality, and then presents the algorithm used to reduce I-V curves to plasma parameters. Several hours of data are presented from August 5, 2006 and March …