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2024

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Articles 151 - 180 of 526

Full-Text Articles in Aerospace Engineering

Simulation Modeling Of An Earth Entry System And Solar Radiation Pressure Module Development, Michael Sean Manwell Aug 2024

Simulation Modeling Of An Earth Entry System And Solar Radiation Pressure Module Development, Michael Sean Manwell

Mechanical & Aerospace Doctoral and Master's Level Projects and Papers

Several trajectory simulation tools are used to model different phases of the Approach, Entry, Descent and Landing (AEDL) phase of NASA’s Mars Sample Return Campaign. Working towards a single simulation tool that models all AEDL phases, this project utilizes Program to Optimize Simulated Trajectories II to simulate the 72-hour exoatmospheric phase of AEDL up till the point of Earth atmospheric entry. This involves developing a new feature for POST2 that captures the forces and moments caused by solar radiation pressure (SRP). Generalizing the vehicle geometry as a combination of primitive shapes, a generalized SRP module was created and implemented into …


A New Trajectory In Uav Safety: Leveraging Reinforcement Learning For Distance Maintenance Under Wind Variations, Xiaolin Xu, Jeffrey Sun Jul 2024

A New Trajectory In Uav Safety: Leveraging Reinforcement Learning For Distance Maintenance Under Wind Variations, Xiaolin Xu, Jeffrey Sun

Journal of Aviation/Aerospace Education & Research

In the field of aviation, safety is a critical cornerstone, and the operation of Unmanned Aerial Vehicle (UAV) systems is deeply connected with this principle. A thorough analysis and rigorous simulation and testing of aircraft systems are essential to avoid severe safety hazards. This paper delves into the safety issue in UAV operations, specifically regarding maintaining minimum safety distances under fluctuating wind conditions. The study introduces a novel solution based on a Deep Deterministic Policy Gradient (DDPG) model, a reinforcement learning method. The DDPG model was trained using a simulated environment created through the Gazebo simulator, with values for wind …


An Enhanced Deep Autoencoder For Flight Delay Prediction, Desmond B. Bisandu, Dan Andrei Soviani-Sitoiu, Irene Moulitsas Jul 2024

An Enhanced Deep Autoencoder For Flight Delay Prediction, Desmond B. Bisandu, Dan Andrei Soviani-Sitoiu, Irene Moulitsas

Journal of Aviation/Aerospace Education & Research

Accurate and timely flight delay prediction cannot be overemphasized because of the ever-increasing demand for air travel and its importance in deploying intelligent transportation systems. Nonetheless, there has not been a universal solution to the problem, as more intelligent flight decision systems are required for the aviation industry's future growth. Existing flight delay classification and prediction approaches are mainly shallow traffic models and do not satisfy many applications in the real world. Our motivation to rethink the deep architecture model for predicting flight delays emanates from the problem. In this research, we proposed a technique that modified stacked autoencoder architecture …


Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt Jul 2024

Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt

Faculty Publications

Fully reversed tension–compression fatigue of a hybrid material comprising polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC) was investigated. The PMC portion had a polyimide matrix reinforced with 15 plies of carbon fibers woven in an eight-harness satin weave (8HSW). The CMC portion had three plies of a quartz-fiber 8HSW fabric in a zirconia-based ceramic matrix. The hybrid PMC/CMC was developed for use in aerospace thermal protection systems (TPS). Hence, the experimental setup aimed to simulate the TPS service environment—the CMC side was kept at 329 °C, whereas the PMC side was open to laboratory air. Compression …


Space Program: Center For Space Research - Austin, Texas #3, Robert J. Twiggs Jul 2024

Space Program: Center For Space Research - Austin, Texas #3, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Space Program: Center for Space Research - Austin, Texas #3" from July 29, 2024.


Space Radiation Assessment And Mitigation: Meeting The Growing Demand For Shielding Solutions By Enhancing Models And Exploring Novel Shielding Opportunities, M. Laura Sorgi Johann Jul 2024

Space Radiation Assessment And Mitigation: Meeting The Growing Demand For Shielding Solutions By Enhancing Models And Exploring Novel Shielding Opportunities, M. Laura Sorgi Johann

Doctoral Dissertations and Master's Theses

The rapid growth of satellite technology and the increasing presence of vulnerable technology and human life in space have highlighted the need for improved shielding materials. Industry standard protocols for shielding are being pushed to their limits as we gain a deeper understanding of the harsh space environment and as chip sizes approach the scale of radiation wavelengths. Furthermore, the commercialization of space is attracting interest from industries such as pharmaceuticals and semiconductor crystal growing, as they explore the potential benefits of zero-gravity production environments. However, the eagerness to develop lighter shielding and the lack of consideration for existing tools …


Space Program: Center For Space Research - Austin, Texas #2, Robert J. Twiggs Jul 2024

Space Program: Center For Space Research - Austin, Texas #2, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Space Program: Center for Space Research - Austin, Texas #2" from July 29, 2024.


Exploring Small-Scale Propellers Performance At Low Advance Ratios, Ali Akber Mollick, Sara Catto, Forrest E. Ames, Clement Tang Jul 2024

Exploring Small-Scale Propellers Performance At Low Advance Ratios, Ali Akber Mollick, Sara Catto, Forrest E. Ames, Clement Tang

Mechanical Engineering Student Publications

The performance of small-scale propellers was experimentally measured at low advance ratios and Reynolds numbers. The propeller diameters range from 14 to 19 inches, with all propellers having the same pitch value of 12. Using a thrust stand situated in a low-speed open-circuit wind tunnel, the propeller thrust, torque, and angular speed were measured at various freestream velocities. The results from this study offer insights on the performance of small propellers at low advance ratios and low Reynolds numbers. Propeller performance results at these conditions tend to be limited in the literatures. At the same pitch value of 12, the …


Modeling Powder Spreadability In Powder-Based Processes Using The Discrete Element Method, Austin T. Sutton, M. Hossein Sehhat, Ming C. Leu, Joseph W. Newkirk Jul 2024

Modeling Powder Spreadability In Powder-Based Processes Using The Discrete Element Method, Austin T. Sutton, M. Hossein Sehhat, Ming C. Leu, Joseph W. Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Powder-bed fusion (PBF) processes refer to a subset of Additive Manufacturing (AM) techniques where powder is spread on the build-plate before melting (by a laser or electron beam). While PBF processes are attractive due to their ability for realizing complex structures that are either difficult or impossible to create through conventional means, the parts fabricated with these techniques can exhibit defects such as pores, inclusions, and excessive surface roughness. To minimize these defects, much research has been dedicated towards process maturation by optimizing laser or electron beam parameters. However, these developmental efforts typically do not address the recoating process where …


Vertiport Ventures: Assessing Operational Feasibility For Evtol Integration In São Paulo’S Helipad And Heliport Infrastructure, Peter E. O'Reilly, Ramy A. Rahimi, Jorge Luiz Rosa Marques, Marco Aurélio Feitosa De A. L. Babadopulos1 Jul 2024

Vertiport Ventures: Assessing Operational Feasibility For Evtol Integration In São Paulo’S Helipad And Heliport Infrastructure, Peter E. O'Reilly, Ramy A. Rahimi, Jorge Luiz Rosa Marques, Marco Aurélio Feitosa De A. L. Babadopulos1

Publications

The objective of this study is to assess the operational viability of introducing Electric Vertical Take-Of and Landing (eVTOL) vehicles in São Paulo and its metropolitan area, utilizing existing helipads and helicopter infrastructure. eVTOL aircraft, capable of vertical take-of and landing like helicopters, difer from traditional helicopters in their propulsion systems, with eVTOLs typically featuring multiple smaller electric motor-driven propulsion units instead of internal combustion engines and mechanical transmissions (Schuchardt et al. 2023). The study specifcally targets eVTOLs with the capacity to transport a minimum of four passengers and one pilot for distances of at least 50 km. Appendix provides …


Notes For Contributors, Space And Defense Jul 2024

Notes For Contributors, Space And Defense

Space and Defense

No abstract provided.


Waging Peace On The Final Frontier 64th Academy Assembly Proceedings, Space And Defense, Madison Walker Jul 2024

Waging Peace On The Final Frontier 64th Academy Assembly Proceedings, Space And Defense, Madison Walker

Space and Defense

In October 2022, the 64th annual Academy Assembly at the U.S. Air Force Academy took up the theme of “Waging Peace on the Final Frontier.” The following are proceedings of roundtables held by select undergraduates from around the country on questions of space policy & strategy.


Revitalizing America's Low-Yield Deterrent, Alex Kleitz Jul 2024

Revitalizing America's Low-Yield Deterrent, Alex Kleitz

Space and Defense

An array of low-yield weapons will play a vital role in integrated deterrence. *The following essay, submitted in June 2022, earned the Junior Division USSTRATCOM General Larry D. Welch Deterrence Writing Award.


Annual Truman Lecture Usafa 64th Academy Assembly, John Shaw Jul 2024

Annual Truman Lecture Usafa 64th Academy Assembly, John Shaw

Space and Defense

In October 2022, on the occasion of the 64th annual Academy Assembly, focused on “Waging Peace on the Final Frontier,” the deputy commander of USSPACEOM Lieutenant General John Shaw spoke at the Air Force Academy’s endowed Truman Lecture, which itself was created to inspire cadets toward careers in National Security leadership.


Usafa 64th Academy Assembly Banquet Keynote On Nasa Transformation, Madison Walker, Lori Garver Jul 2024

Usafa 64th Academy Assembly Banquet Keynote On Nasa Transformation, Madison Walker, Lori Garver

Space and Defense

In October 2022, at the 64th annual Academy Assembly, focused on “Waging Peace on the Final Frontier,” the former deputy administrator of NASA the Honorable Lori Garver spoke at the Air Force Academy’s 64th Academy Assembly banquet keynote on the implications of NASA transformation for international security. She was introduced in a pre-recorded video by Susan Eisenhower, honorary founder of USAFA’s Eisenhower Center, and interviewed by USAFA Institute for Future Conflict Fellow Madison Walker.


The Unified Command Plan For A New Cold War, David Stilwell Jul 2024

The Unified Command Plan For A New Cold War, David Stilwell

Space and Defense

No abstract provided.


Protecting The Cosmos: Defining Celestial Bodies In The Outer Space Treaty, David Epstein Jul 2024

Protecting The Cosmos: Defining Celestial Bodies In The Outer Space Treaty, David Epstein

Space and Defense

Lack of a clear definition of the term “celestial bodies” as used in the 1967 Outer Space Treaty risks exporting legal and political conflict into the cosmos. *This essay is updated from a previously published version and appears here by permission of the Journal of Space Law at Ole Miss.


Editor's Note, Damon Coletta Jul 2024

Editor's Note, Damon Coletta

Space and Defense

No abstract provided.


Table Of Contents, Space And Defense Jul 2024

Table Of Contents, Space And Defense

Space and Defense

No abstract provided.


Front Matter, Space And Defense Jul 2024

Front Matter, Space And Defense

Space and Defense

No abstract provided.


Space And Defense Volume 15 No. 1 Spring 2024 (Whole Issue), Space And Defense Jul 2024

Space And Defense Volume 15 No. 1 Spring 2024 (Whole Issue), Space And Defense

Space and Defense

No abstract provided.


Computational Fluid Dynamics Visualization For Unmanned Aerial Systems In Bridge Inspections, Kristoffer B. Borgen, John Mott Jul 2024

Computational Fluid Dynamics Visualization For Unmanned Aerial Systems In Bridge Inspections, Kristoffer B. Borgen, John Mott

Journal of Aviation Technology and Engineering

Bridge inspections are an expensive and time-consuming process, varying significantly with a bridge’s style, height, width, and length. Inspections create interruptions that interfere with bridge use, as the examination requires partial or total closure, causing traffic delays. Unmanned aerial system (UAS) use has increased significantly over the past decade, including assistance and coordination during bridge inspections. However, the impact on a UAS from high winds and turbulent airflows induced by a bridge’s structure can decrease flight safety during inspections. Visualization of these hazards is difficult for UAS operators; therefore, a process to estimate the velocity and locations of these hazardous …


Space Program: Center For Space Research - Austin, Texas #1, Robert J. Twiggs Jul 2024

Space Program: Center For Space Research - Austin, Texas #1, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Space Program: Center for Space Research - Austin, Texas" from July 12, 2024.


Slimsat, Robert J. Twiggs, Nick Pugh Jul 2024

Slimsat, Robert J. Twiggs, Nick Pugh

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs and Nick Pugh titled "SlimSat" from July 11, 2024.


Atmospheric Waves Experiment (Awe) Thermal Control System: From Design Through On-Orbit Thermal Performance, Matthew I. Ralphs, Mike Holt Jul 2024

Atmospheric Waves Experiment (Awe) Thermal Control System: From Design Through On-Orbit Thermal Performance, Matthew I. Ralphs, Mike Holt

Space Dynamics Laboratory Publications

The Atmospheric Waves Experiment (AWE) will provide the first global characterization of atmospheric waves that originate in Earth’s lower atmosphere and affect space weather. The instrument has been installed on the International Space Station (ISS) ExPRESS Logistics Carrier (ELC) 1 since November 2023. The main thermal control system consists of a passive, ambient temperature, bi-directional radiator to which pyrolytic graphite sheet (PGS) thermal straps connect four independent detectors, whose temperatures are actively controlled by thermoelectric coolers (TECs). This paper discusses the thermal design, thermal model correlation efforts (both with test temperature data and flight temperature data), and how the predictions …


An Integrated Space Test Lexicon: A Taxonomy For The Integrated Test And Evaluation Of Space Systems, Stephen K. Tullino, Andrew S. Keys, Robert A. Bettinger, Amy M. Cox, David R. Jacques Jul 2024

An Integrated Space Test Lexicon: A Taxonomy For The Integrated Test And Evaluation Of Space Systems, Stephen K. Tullino, Andrew S. Keys, Robert A. Bettinger, Amy M. Cox, David R. Jacques

Faculty Publications

The proposed Integrated Space Test Lexicon is intended to amalgamate the numerous definitions of integrated (IT or IT&E), development test (DT or DT&E), and operational test (OT or OT&E) into unified, service-wide definitions, aligned with the Space Test Enterprise Vision. Refining such definitions will help distill the core characteristics of these fundamental test types to first identify space system activities composing what is traditionally known as DT and OT, then to provide a means of how these activities fit into the IT paradigm and support space system development. In forging a common understanding of how DT and OT support space …


Unmanned Aerial Vehicle (Uav)-Based High-Throughput Phenotyping For Maize Improvement, Eric T. Rodene Jul 2024

Unmanned Aerial Vehicle (Uav)-Based High-Throughput Phenotyping For Maize Improvement, Eric T. Rodene

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Modern breeding programs rely heavily on efficiently screening large numbers of genotypes for agronomic traits, such as disease resistance, drought tolerance, and yield. Identifying the genetic loci or genes associated with these traits using GWAS or functional analyses will benefit future plant breeding efforts seeking to incorporate these traits into new crop varieties, whether through conventional breeding or gene editing techniques. Unmanned aerial vehicle (UAV)-based image data has been increasingly used for this task, as it allows entire test plots to be quickly and cost-effectively phenotyped. In my research, I have developed methods to improve the accuracy of machine learning …


Optimization Of A Plate Beam System For Energy Harvesting Using A Piezoelectric Material, Jose Manuel Almendros Espantaleon Jul 2024

Optimization Of A Plate Beam System For Energy Harvesting Using A Piezoelectric Material, Jose Manuel Almendros Espantaleon

Doctoral Dissertations and Master's Theses

With a continuously growing demand for power, driven by the need to reduce our environmental footprint, this research provides an examination of the potential of energy harvesting with smart materials technology and its practical applications. The energy harvesting system considered here works on generating energy through vibrations of a piezoelectric material beam which will undergo sustained vibrations due to flow of air over its surface. It is assumed that sustained limit cycle oscillations of this system will occur at the flutter velocity. This research creates an optimization framework to obtain the best values of parameters that will result in the …


Assessing The Impact Of Spacecraft Fragmentation In The Cislunar Region, Marta Lopez Castro Jul 2024

Assessing The Impact Of Spacecraft Fragmentation In The Cislunar Region, Marta Lopez Castro

Doctoral Dissertations and Master's Theses

In the last decades, space missions have followed great advancements due to technological improvements and the extensive research developed in the field. Some of these missions are increasingly focusing on satellites orbiting the Moon. The Cislunar region is known to have a higher non-linear chaotic component in the dynamics compared to the low-Earth environment. This research is focused on studying the impact that a satellite explosion has in the Cislunar vicinity. The study is conducted for different periodic orbits that are key destinations for Cislunar traffic. By varying the initial conditions, simulations of explosions at different locations of the orbits …


In Situ Synthesis, Characterization And Photocatalytic Efficacy Of Silver-Enhanced Mxene And Graphene Nanocomposites, Kishore Chand, M. Mustafa Azeem, Muhammad Nazim Lakhan, Mukhtiar Ahmed, Muhammad Jehanzaib Aslam, Ahmer Hussain Shah Jul 2024

In Situ Synthesis, Characterization And Photocatalytic Efficacy Of Silver-Enhanced Mxene And Graphene Nanocomposites, Kishore Chand, M. Mustafa Azeem, Muhammad Nazim Lakhan, Mukhtiar Ahmed, Muhammad Jehanzaib Aslam, Ahmer Hussain Shah

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The emergence of 2D materials has significantly expanded the wide range of nanomaterials with diverse applications. Notably, their high conductivity, catalytic efficiency, and hydrophobicity have fueled heightened research interests for water treatment applications. This research aimed to investigate the synthesis and characterization of MXene and reduced graphene oxide (rGO) nanocomposites with silver nanoparticles (Ag) for enhanced catalytic activity in the decomposition of Direct Blue-24 dye. In this study, we employed well-established methods, previously documented in the literature, to prepare two distinct nanocomposites. Novel nanocomposites, namely reduced graphene oxide–silver nanoparticles (rGO–Ag) and MXene–silver nanoparticles (MXene–Ag), were synthesized using the hydrothermal and …