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Articles 961 - 990 of 11115

Full-Text Articles in Engineering

Extended-Duration Satellite Testing Via Altitude-Controlled High-Altitude Balloon, Drew Early, Evan Champney, Nikki Allen, Riley Galatis, Lukas Hezel, Joseph Kloess, Andrew Donnell, Sam Whitlock, Kaden Queener Jan 2025

Extended-Duration Satellite Testing Via Altitude-Controlled High-Altitude Balloon, Drew Early, Evan Champney, Nikki Allen, Riley Galatis, Lukas Hezel, Joseph Kloess, Andrew Donnell, Sam Whitlock, Kaden Queener

Von Braun Symposium Student Posters

Undergraduate runner-up, 2025 Von Braun Symposium Student Poster Contest


Dynamic Stability Test Technique For Blunt Bodies In A Magnetic Suspension And Balance System, Caleb Hull, Colin Britcher, Dave E. Cox, Mark Schoenenberger, Hisham M. Shehata Jan 2025

Dynamic Stability Test Technique For Blunt Bodies In A Magnetic Suspension And Balance System, Caleb Hull, Colin Britcher, Dave E. Cox, Mark Schoenenberger, Hisham M. Shehata

Mechanical & Aerospace Engineering Faculty Publications

Techniques for the measurement of subsonic dynamic stability derivatives of blunt-body re-entry capsules are being developed using a Magnetic Suspension and Balance System at NASA Langley Research Center. The measured aerodynamics of a 45-degree sphere-cone similar to configurations being considered for Mars Sample Return Earth Entry Vehicle are reported. A novel test method has been developed where forced oscillatory translation of a test article is used to excite yaw attitude oscillations. The forced motion is then halted to observe free-to-oscillate behavior of the test article. Parameter identification methods are used to extract static and dynamic yawing moment stability characteristics from …


Mass-Adaptive Admittance Control For Robotic Manipulators, Hossein Gholampour, Jonathon E. Slightam, Logan E. Beaver Jan 2025

Mass-Adaptive Admittance Control For Robotic Manipulators, Hossein Gholampour, Jonathon E. Slightam, Logan E. Beaver

Mechanical & Aerospace Engineering Faculty Publications

Handling objects with unknown or changing masses is a common challenge in robotics, often leading to errors or instability if the control system cannot adapt in realtime. In this paper, we present a novel approach that enables a six-degrees-of-freedom robotic manipulator to reliably follow waypoints while automatically estimating and compensating for unknown payload weight. Our method integrates an admittance control framework with a mass estimator, allowing the robot to dynamically update an excitation force to compensate for the payload mass. This strategy mitigates end-effector sagging and preserves stability when handling objects of unknown weights. We experimentally validated our approach in …


Optimal Manipulation Motion Action Planner Enabled By Physics Informed Neural Networks, Jonathon E. Slightam, Logan E. Beaver Jan 2025

Optimal Manipulation Motion Action Planner Enabled By Physics Informed Neural Networks, Jonathon E. Slightam, Logan E. Beaver

Mechanical & Aerospace Engineering Faculty Publications

Autonomous robotic manipulation in unstructured environments faces many challenges and is hindered by capabilities that bridge the gap between perception and acting on the world. Action plans that are centric to object motion rather than end-of-arm tooling behavior may aid this. This paper presents an autonomous action planner for a feedback linearizeable system comprised of three base motions that can be leveraged on their own or in combination to give custom motion plans. The optimization routine for the three different types of motion are presented, which are integrated into physics informed neural networks. A component of this is the autonomy …


Mitigating Out-Of-Plane Fiber Waviness In Afp Laminates With Tow-Gaps Via Selective Placement Of Thermoplastic Veils, Ahmadreza Ravangard, Kuthan Celebi, Sergii G. Kravchenko, Oleksandr G. Kravchenko Jan 2025

Mitigating Out-Of-Plane Fiber Waviness In Afp Laminates With Tow-Gaps Via Selective Placement Of Thermoplastic Veils, Ahmadreza Ravangard, Kuthan Celebi, Sergii G. Kravchenko, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

Fiber tow-gaps and overlaps formed during the Automated Fiber Placement (AFP) process pose a significant challenge by introducing non-uniform composite morphologies, often characterized by resin-rich regions and fiber waviness. These defects occur as deposited fibers sink into the gap regions during consolidation, with gap geometry determined during path planning. Such morphological inconsistencies can compromise structural reliability by initiating premature failure, particularly through localized out-of-plane waviness and resin accumulation. This study investigates the integration of high melting temperature thermoplastic veils, specifically polyetherimide (PEI), into fiber tow-gaps as a method to prevent ply sinking and reduce fiber waviness on both internal and …


Extending The Applicability Of Thermal Protection System Ballistic Limit Equations Beyond The Testable Regime, William P. Schonberg, Michael D. Squire Jan 2025

Extending The Applicability Of Thermal Protection System Ballistic Limit Equations Beyond The Testable Regime, William P. Schonberg, Michael D. Squire

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Spacecraft use thermal insulation in their design, which is usually placed on their exterior. As such, it is susceptible to high-speed impacts by meteoroids and orbital debris, which can damage it to a point where the protection it offers is below acceptable limits. It is important to be able to characterize expected levels of damage stemming from such high-speed impacts. In this paper, we extend the applicability of a previously developed ballistic limit equation (BLE) for one such thermal insulation material using the results of a series of Smooth Particle Hydrodynamics Code (SPHC) impact simulations at velocities in excess of …


Anisotropic And Temperature-Tunable Second-Harmonic Vortex Generation In Ferroelectric Nbocl2 Holograms, Jayanta Deka, Xiaodong Yang, Jie Gao Jan 2025

Anisotropic And Temperature-Tunable Second-Harmonic Vortex Generation In Ferroelectric Nbocl2 Holograms, Jayanta Deka, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Optical vortex beams with helical phase fronts have immense potential to enhance data capacity due to the unbounded values of orbital angular momentum. Chip-scale platforms for producing vortex beams are of paramount importance for a variety of applications. On the other hand, 2D materials with unique optical properties are essential for developing multifunctional ultrathin photonic devices. Here, anisotropic and temperature-tunable second-harmonic vortex beam generation is demonstrated with ultrathin ferroelectric niobium oxide dichloride (NbOCl2) fork holograms. The polarization-resolved Raman measurements are performed on the NbOCl2 crystal to understand the anisotropic behavior of the Raman modes. It is demonstrated …


Hydrogen Standards And Aviation Sustainability, Eva Maleviti, Evan Stamoulis, Elen Paraschi Jan 2025

Hydrogen Standards And Aviation Sustainability, Eva Maleviti, Evan Stamoulis, Elen Paraschi

Publications

Standards from ISO, SAE, and ASTM are essential for certification, safety, and sustainability validation.


Hydrogen Readiness In Aviation & Challenges- Technology Meets Regulation And Market Demand, Eva Maleviti Jan 2025

Hydrogen Readiness In Aviation & Challenges- Technology Meets Regulation And Market Demand, Eva Maleviti

Publications

Where technology meets regulation and market demand.


Program And Proceedings: Nebraska Academy Of Sciences 1880–2025, 145th Anniversary Year, One Hundred-Thirty-Fifth Annual Meeting Jan 2025

Program And Proceedings: Nebraska Academy Of Sciences 1880–2025, 145th Anniversary Year, One Hundred-Thirty-Fifth Annual Meeting

Nebraska Academy of Sciences: Programs and Proceedings

Program

Aeronautics and Space Science

Biological and Medical Sciences

Biology

Chemistry

Earth Sciences

Science Education

Anthropology

Applied Science and Technology

Physics and Engineering

Forensic Sciences

Ecology, Sustainability, and Environmental Science

Maiben Lecture: Mary Ann Vinton, "State of the Academy"

Friends of Science Awards: David Crouse and Daniel Sitzman


Generative Adversarial Networks For Dimensionality Reduction In Evtol Aircraft Takeoff Trajectory Optimization, Samuel Sisk, Farzaam Khorasani-Gerdehkouhi, Abdulaziz Abutunis, K. Chandrashekhara, Xiaosong Du Jan 2025

Generative Adversarial Networks For Dimensionality Reduction In Evtol Aircraft Takeoff Trajectory Optimization, Samuel Sisk, Farzaam Khorasani-Gerdehkouhi, Abdulaziz Abutunis, K. Chandrashekhara, Xiaosong Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric vertical takeoff and landing (eVTOL) aircraft play a key role in urban air mobility (UAM), which aims to alleviate traffic congestion in urban areas. Despite their value, eVTOL aircraft suffer from battery energy consumption, which affects their range and endurance in real world flight tasks. Especially, the takeoff process has been identified for excessive power demands. Multidisciplinary analysis and optimization manage to discover optimal takeoff trajectories with minimum energy consumption while balancing multidisciplinary trade-offs, such as short distance takeoff and passengers' comfort. However, conventional parametrization methods (such as B-spline curves) leverage an empirically high-dimensional design space to include real …


Multifidelity Dust Erosion Analysis Of Mars Entry Vehicles, Adam Boland, Dominic Zanti, Serhat Hosder, Andrew Hinkle Jan 2025

Multifidelity Dust Erosion Analysis Of Mars Entry Vehicles, Adam Boland, Dominic Zanti, Serhat Hosder, Andrew Hinkle

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The objective of this paper is to present a multifidelity approach for estimating recession rate and kinetic energy impact rate on the surface of planetary entry vehicles operating in dusty atmospheric environments at hypersonic speeds. The multifidelity model used a co-Kriging approach that combined a low-fidelity correlation with a correction factor from high-fidelity CFD solutions. The developed multifidelity model enables efficient and accurate exploration of a design space to determine at what conditions encountering dust is most dangerous to TPS survivability. Two sample problems are used to demonstrate the effectiveness of the approach: the Mars 2020 lander and a HIAD-type …


Improving Neural Network Efficiency With Multi-Fidelity And Dimensionality Reduction Techniques, Vignesh Sella, Thomas O'Leary-Roseberry, Xiaosong Du, Mengwu Guo, Joaquim R.R.A. Martins, Omar Ghattas, Karen Willcox, Anirban Chaudhuri Jan 2025

Improving Neural Network Efficiency With Multi-Fidelity And Dimensionality Reduction Techniques, Vignesh Sella, Thomas O'Leary-Roseberry, Xiaosong Du, Mengwu Guo, Joaquim R.R.A. Martins, Omar Ghattas, Karen Willcox, Anirban Chaudhuri

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Design problems in aerospace engineering often require numerous evaluations of expensive to-evaluate high-fidelity models, resulting in prohibitive computational costs. One way to address the computational cost is through building surrogates, such as deep neural networks (DNNs). However, DNNs may only be an effective surrogate when sufficient evaluations of the high-fidelity model are required such that the up-front training cost is amortized, or in situations that require real-time responses (such as interactive visualizations). Typically, the data requirements for adequately accurate training of DNNs are often impractical for engineering applications. To alleviate this issue, the proposed work utilizes output dimensionality reduction along …


Characterizing Intralaminar Distal Crack And Delamination In Multidirectional Laminates Under Low Velocity Impact: Modeling Approach With Ultrasound Testing Validation, Niildiip Chandraa, Rachel Van Lear, Arief Yudhanto, Yuqing Zhao, David A. Jack, Douglas E. Smith Jan 2025

Characterizing Intralaminar Distal Crack And Delamination In Multidirectional Laminates Under Low Velocity Impact: Modeling Approach With Ultrasound Testing Validation, Niildiip Chandraa, Rachel Van Lear, Arief Yudhanto, Yuqing Zhao, David A. Jack, Douglas E. Smith

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multidirectional laminated composites are essential for load-bearing structures, especially under frequent impact loading. While existing modeling techniques simulate various impact damage modes, our understanding of the underlying mechanisms, specifically the initiation and progression of intralaminar distal cracks and interlaminar delamination, needs improvement. Validating these mechanisms is crucial for enhancing modeling accuracy and expediting the design process. In this work, we propose a three-dimensional finite element modeling (3D FEM) approach aimed at elucidating the impact damage mechanisms in multidirectional carbon fiber reinforced polymer (CFRP). Our model incorporates cohesive zone models (CZM) to simulate the behavior of intralaminar cracks at distal points …


Phase Change Cells And Verification Of Gallium As Thermal Calibration Reference In Space, Harri Latvakoski, T. Shane Topham, Gail Bingham, Mike Watson, Igor Podolski Jan 2025

Phase Change Cells And Verification Of Gallium As Thermal Calibration Reference In Space, Harri Latvakoski, T. Shane Topham, Gail Bingham, Mike Watson, Igor Podolski

Space Dynamics Laboratory Publications

• Phase change cell introduction

• Design and ground testing of on-orbit phase cells

• ISS phase cell flight experiment


Radiometric Sensor Level Calibration For Remote Sensing (Planning, Testing, And Operation), Joe Tansock Jan 2025

Radiometric Sensor Level Calibration For Remote Sensing (Planning, Testing, And Operation), Joe Tansock

Space Dynamics Laboratory Publications

Contents

  • What is Calibration and Why is it Important (example) 
  • Remote Sensor Calibration Approaches
  • Typical Space-based Sensor Lifecycle and Calibration Efforts at SDL
  • EO Calibration Applications (example) 
  • Example Calibrations at SDL
  • Calibration Testing at SDL and example Calibration Equipment
  • Calibration is Multi-Path
  • Student Employment/Projects to Support SDL Calibration


Calibration For Small Satellite Payloads, Jason Knudsen, Christian Conkle, Alex Allgrunn, Deron Scott Jan 2025

Calibration For Small Satellite Payloads, Jason Knudsen, Christian Conkle, Alex Allgrunn, Deron Scott

Space Dynamics Laboratory Publications

SDL Presentation on Calibration for Small Satellite Payloads


Rbi Ground Calibration, Harri Latvakoski, Greg Cantwell, James Peterson, Joel Cardon Jan 2025

Rbi Ground Calibration, Harri Latvakoski, Greg Cantwell, James Peterson, Joel Cardon

Space Dynamics Laboratory Publications

• RBI overview

• Ground calibration objectives

• Calibration configurations & chamber setup

• Calibration tests & equipment


Small Satellite Payload Calibration, Deron Scott, Cole Miller, Eli Salay, Shane Canfield, Scott Hansen, Matt Berghout, Jan Kunzler, Duane Miles Jan 2025

Small Satellite Payload Calibration, Deron Scott, Cole Miller, Eli Salay, Shane Canfield, Scott Hansen, Matt Berghout, Jan Kunzler, Duane Miles

Space Dynamics Laboratory Publications

SmallSat missions have cost, time, and scale limitations. Calibration methods can be optimized to enable mission success at a low cost by providing customers the best “bang for their buck.”


Multi-Layered Security Approaches For A Modular Open Network Architecture-Based Satellite, Brandon Shirley, Quinn Young, Peter Wegner, Jacob Christensen, Jeffrey Janicik Jan 2025

Multi-Layered Security Approaches For A Modular Open Network Architecture-Based Satellite, Brandon Shirley, Quinn Young, Peter Wegner, Jacob Christensen, Jeffrey Janicik

Space Dynamics Laboratory Publications

Overview

  • Introduction
  • Open System Architecture (OSA) and Modular Open Network Architecture (MONA) background
  • Security Challenges
  • Security Principles
  • Solutions


The Atmospheric Waves Experiment (Awe), Ludger Scherliess, Yucheng Zhao, Pierre-Dominique Pautet Jan 2025

The Atmospheric Waves Experiment (Awe), Ludger Scherliess, Yucheng Zhao, Pierre-Dominique Pautet

Space Dynamics Laboratory Publications

Modern theory and modeling indicate vertically propagating Gravity Waves (GWs), waves generated primarily by severe weather disturbances, have profound effects on the variability and mean state of the Ionosphere-Thermosphere-Mesosphere (ITM) system, and can significantly impact space-based communications, navigation, and tracking.


Physics-Constrained Generative Artificial Intelligence For Rapid Takeoff Trajectory Design, Samuel Sisk, Xiaosong Du Jan 2025

Physics-Constrained Generative Artificial Intelligence For Rapid Takeoff Trajectory Design, Samuel Sisk, Xiaosong Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The urban air mobility (UAM) industry is rapidly growing to alleviate regional transportation congestion. Electric vertical takeoff and landing (eVTOL) aircraft plays a critical role in this growth due to their efficiency and reduced operating cost. However, excessive energy demands by the takeoff phase impact the practicality of the aircraft. Conventional multidisciplinary analysis and optimization (MDAO) identifies a minimum energy trajectory but can be computationally intensive due to iteratively evaluating high-fidelity simulation models. In addition, complex constraints in practical MDAO pose crucial challenges to the already demanding process. Surrogate models enable efficient design optimization, but complex constraints could prohibit surrogate-based …


Versatile Injector Platform: A Modular Design For Supersonic Flow Research, Connor Bell, Davide Viganò Jan 2025

Versatile Injector Platform: A Modular Design For Supersonic Flow Research, Connor Bell, Davide Viganò

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fuel–air mixing remains a critical challenge in the development of high-speed air-breathing propulsion due to the extremely short residence times in supersonic combustors. Experimental studies are essential to investigate the underlying mixing mechanisms, but they require injection systems that can deliver repeatable and controlled flow conditions. In this work, we present the design of a modular strut-type injection platform developed for the Missouri S&T Supersonic Wind Tunnel. In its initial configuration, the platform features a planar trailing-edge slit to generate a two-dimensional jet and includes interchangeable trailing-edge modules to support a wide range of geometries and flow-control strategies. Designed with …


Little Problems: Photosynthetic Textile Treatments As A Source Of Oxygen, Morgan Campbell Jan 2025

Little Problems: Photosynthetic Textile Treatments As A Source Of Oxygen, Morgan Campbell

Open Access Master's Theses

During human space travel, oxygen (O2) must be stored and carried aboard the shuttle for the entire journey; compressed O2 is highly flammable and combustible, thus doing so puts the crew’s lives at risk in the event of a fire (Mandel, 2019). By creating O2 onsite, the necessity of compressed O2 canisters and the associated risks can be reduced or erased entirely. Photosynthesis, the process through which plants convert atmospheric carbon dioxide (CO2) into O2, is one method of creating O2 (Lorch, 2020). The National Aeronautics and Space Administration (NASA) has experimented with photosynthetic O2 systems since its inception but …


Investigation Of Subsurface Thermal Radiation Phenomena In Fibrous Thermal Protection Systems, Colby L. Gore Jan 2025

Investigation Of Subsurface Thermal Radiation Phenomena In Fibrous Thermal Protection Systems, Colby L. Gore

Theses and Dissertations--Science, Technology, Engineering, and Mathematics (STEM) Education

Atmospheric re-entry induces intense thermal stress upon vehicles through a high-enthalpy boundary layer that encompasses the craft. To protect these vehicles, numerous insulative methods, known as thermal protection systems (TPS), are deployed to protect the craft during re-entry. The TPS materials insulate the craft from intense thermal transmission that would terminate a mission. In hypersonic environments, vast temperature gradients exist, enforcing the exponential effect of thermal radiation. However, TPS materials are commonly low-density fibrous materials that allow for the potential to be penetrated by thermal radiation. A series of arc-jet tests was completed to replicate enhanced radiative conditions in a …


Numerical Investigation Of Wind Disturbance Around A Multirotor Uav In Crosswind And Vertical Flight, Garrison Page Jan 2025

Numerical Investigation Of Wind Disturbance Around A Multirotor Uav In Crosswind And Vertical Flight, Garrison Page

Theses and Dissertations--Mechanical and Aerospace Engineering

Uncrewed Aerial Vehicles (UAVs) are being increasingly utilized in a wide range of research applications, especially in meteorology. This is due to such factors as their ease of use, maneuverability compared to other forms of data collection, and for rotor- craft, the ability to hover. However, the rotorwash generated by UAVs can introduce significant disturbances, potentially affecting measurement accuracy from sensors. While several studies have investigated the rotorwash of individual UAVs utilizing Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD), there is limited exploration into how different rotor configurations and external wind conditions influence regions of turbulent flow around …


Development Of An Immersed Boundary Method-Wall Modeled Large Eddy Simulation Approach For Incompressible Flows And Aeroacoustic Predictions, John C. Higgins Jan 2025

Development Of An Immersed Boundary Method-Wall Modeled Large Eddy Simulation Approach For Incompressible Flows And Aeroacoustic Predictions, John C. Higgins

Theses and Dissertations--Mechanical and Aerospace Engineering

The performance capabilities of rotorcraft have improved significantly in the past decade as both manned and unmanned rotorcraft become a larger part of future transportation systems. Private companies as well as various government offices have worked to develop capabilities ranging from transportation/package delivery to intelligence/surveillance to livestock monitoring. Their practicality in both rural and urban areas, however, is questionable due to the significant tonal and broadband noise which is produced by the rotors. Public acceptance of rotorcraft, namely small Unmanned Aerial Vehicles (sUAVs), in transportation systems is an issue largely associated with the noise generation and it's effect on nearby …


Direct Numerical Simulation Of Pulsating Flow In Curved Pipes: Insights Into Aortic Dissection In Humans, Gokul Anugrah Gopakumar Jan 2025

Direct Numerical Simulation Of Pulsating Flow In Curved Pipes: Insights Into Aortic Dissection In Humans, Gokul Anugrah Gopakumar

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation investigates the hemodynamics of pulsating blood flow in curved vessels through direct numerical simulations (DNS), with the overarching aim of uncovering fluid dynamic mechanisms linked to the onset and progression of aortic dissection in humans. The work is structured in two parts: (i) fundamental studies in idealized geometries and (ii) preliminary investigations in patient-specific anatomies. In the first part, curved pipe models representing the aortic arch are used to isolate the effects of pulsation frequency, amplitude ratio, and curvature ratio on transitional and turbulent flow dynamics. The simulations reveal that curvature-driven centrifugal forces shift the peak velocity toward …


High-Altitude Balloon-Launched Uncrewed Aircraft System Measurements Of Atmospheric Turbulence And Qualitative Comparison With Infrasound Microphone Response, Anisa Haghighi Jan 2025

High-Altitude Balloon-Launched Uncrewed Aircraft System Measurements Of Atmospheric Turbulence And Qualitative Comparison With Infrasound Microphone Response, Anisa Haghighi

Theses and Dissertations--Mechanical and Aerospace Engineering

This study explores the use of a balloon-launched uncrewed aircraft system (UAS) to measure atmospheric turbulence in the troposphere and lower stratosphere using both wind velocity measurements and infrasonic acoustic energy. The UAS, a glider configured for autonomous descent along a predefined trajectory, had on board, in situ sensors to capture thermodynamic and kinematic atmospheric parameters. Additionally, it carried an infrasonic microphone to evaluate its potential for remotely detecting clear-air turbulence by capturing infrasonic waves. The system’s performance was assessed over the course of three test flights conducted in New Mexico, USA, in 2021. The descent enabled high-resolution profiling, with …


Simulation-To-Hardware Validation Of Mpc For Binary Thruster 2d Cubesat Control, Aevar Amundinusarson Oefjoerd Jan 2025

Simulation-To-Hardware Validation Of Mpc For Binary Thruster 2d Cubesat Control, Aevar Amundinusarson Oefjoerd

Theses and Dissertations--Mechanical and Aerospace Engineering

Small satellites must execute precise, fuel-limited maneuvers under strict actuation and operational constraints. Model Predictive Control (MPC) is a suitable approach because it optimizes future actions while explicitly enforcing these limits. This work evaluates (1) whether MPC can operate in real time using binary (on/off), asymmetric thrusters, and (2) whether a high-fidelity digital twin can be used to tune and validate the controller prior to hardware testing.

An MPC framework was implemented on a planar satellite prototype that floats on air bearings, operates at 16.7 Hz (60 ms period), and uses eight binary thrusters exhibiting up to 13.2% variation in …