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Articles 1861 - 1890 of 11097

Full-Text Articles in Aerospace Engineering

No Method To Madness: The Failures Of Madman Diplomacy In All Its Forms, Henry Gilchrist Oct 2023

No Method To Madness: The Failures Of Madman Diplomacy In All Its Forms, Henry Gilchrist

Space and Defense

Student Voices

Madman diplomacy fails to work as advertised. Internal contradiction of the strategy in it s ideal form reduce the chances it will succeed in future crises.

Effective deterrence requires an actor to pair powerful capabilities with a believable will to use them. The world of United States' dominance has relegated the question of will to the periphery. However, the U.S. is emerging from its hegemony with enough self-awareness to acknowledge the painful consequences of this relegation. Democratic restraint has historically played an important role in nuclear deterrence for obvious reasons, and the issue of will deficit is not …


Boosting Space Diplomacy At State, David A. Epstein Oct 2023

Boosting Space Diplomacy At State, David A. Epstein

Space and Defense

Notes from the Field:

Space diplomacy remains an esoteric specialty of State.

With ever-increasing speed, humanity is expanding the scope of its activities in outer space, thanks to private enterprise as well as via national pursuits. In the last two years alone, for example, the number of active and defunct satellites in lower Earth orbit has increase by more than 50 percent, to around 5,000, with plans to add tens of thousands more in the coming years. Equally surprising, these satellites are owned and operated by nearly 100 difference countries and organizations around the world - no just the small …


Contextualizing Russia's Hypersonic Threat: Perceptions, Motivations, And Strategic Stability., Jeffery D. Taylor Oct 2023

Contextualizing Russia's Hypersonic Threat: Perceptions, Motivations, And Strategic Stability., Jeffery D. Taylor

Space and Defense

Rather than specific military objectives in Europe, Russian hypersonic missile development manifests deep-rooted perceptions of the United States and NATO undermining strategic through missile defense.


Future Directions For Great Power Nuclear Arms Control, T. Justin Bronder Oct 2023

Future Directions For Great Power Nuclear Arms Control, T. Justin Bronder

Space and Defense

Extending the current New START regime can help maintain traditional strategic stability; however, such an approach fails to address destabilizing trends related to non-nuclear strategic technologies and China's expanding forces.

Arms control in the nuclear age has proved a useful tool of national security, meeting ends as diverse as reducing the risks of nuclear war to channeling strategic competition. Yet recent trends indicate arms control may be at an inflection point; the suitability of this tool in general and the viability of securing new agreements specifically are both unclear. The New Strategic Arms reduction Treaty (New START) extension somewhat reverses …


Editor's Note Vol. 13 No. 1, Damon Coletta Oct 2023

Editor's Note Vol. 13 No. 1, Damon Coletta

Space and Defense

Editor's Note


Table Of Contents Vol. 13 No. 1, Space And Defense Oct 2023

Table Of Contents Vol. 13 No. 1, Space And Defense

Space and Defense

No abstract provided.


Front Matter Vol. 13 No. 1, Space And Defense Oct 2023

Front Matter Vol. 13 No. 1, Space And Defense

Space and Defense

No abstract provided.


Augmenting External Surface Pressures’ Predictions On Isolated Low-Rise Buildings Using Cfd Simulations, Md Faiaz Khaled, Aly Mousaad Aly Oct 2023

Augmenting External Surface Pressures’ Predictions On Isolated Low-Rise Buildings Using Cfd Simulations, Md Faiaz Khaled, Aly Mousaad Aly

Faculty Publications

The aim of this paper is to enhance the accuracy of predicting time-averaged external surface pressures on low-rise buildings by utilizing Computational Fluid Dynamics (CFD) simulations. To achieve this, benchmark studies of the Silsoe cube and the Texas Tech University (TTU) experimental building are employed for comparison with simulation results. The paper is structured into three main sections. In the initial part, an appropriate domain size is selected based on the precision of mean pressure coefficients on the windward face of the cube, utilizing Reynolds Averaged Navier-Stokes (RANS) turbulence models. Subsequently, recommendations regarding the optimal computational domain size for an …


Orbital Debris Mitigation: Exploring Cubesat Drag Sail Technology, Robinson Raphael Oct 2023

Orbital Debris Mitigation: Exploring Cubesat Drag Sail Technology, Robinson Raphael

Student Works

In an era marked by remarkable advancements in space exploration and research, the advent of satellite technology has contributed accordingly to the lives of people here on Earth. Through applications that tie into broadband connectivity, weather forecasting, disaster management, etc., the occupancy in orbital domains like Low-Earth Orbit (LEO) only continues to grow. However, the presence of orbital debris emerges as a significant concern, posing threats to both operational satellites and future space missions. Resulting as a consequence due to decades of activities since the launch of Sputnik 1 in 1957, as more countries ventured into space so did the …


Notes For Contributors, Space And Defense Oct 2023

Notes For Contributors, Space And Defense

Space and Defense

No abstract provided.


Book Review: Spies, Lies, And Algorithms: The History And Future Of American Intelligence, Claire Benedix Oct 2023

Book Review: Spies, Lies, And Algorithms: The History And Future Of American Intelligence, Claire Benedix

Space and Defense

The security environment is entering a new threat landscape; one that must be fought in both the physical and virtual world. The seemingly instantaneous progress of digitization and the cyberspace domain threatens to destabilize traditional warfare strategies and intelligence norms. Amy Zegart, an American academic and leading national security expert, outlines the history and future of American intelligence with a specific emphasis on emerging cyber threats in the digital age. In Spies, Lies, and Algorithms, Zegart explains the roles of technological breakthroughs in a world of big data by chronicling the history of intelligence education and organizational reform, the evolution …


Communicating Deterrence Thresholds In Cyberspace Through Global Normas, Leila Yanni Oct 2023

Communicating Deterrence Thresholds In Cyberspace Through Global Normas, Leila Yanni

Space and Defense

Student Contribution.

Cyberspace refers to a purely virtual arena that has become increasingly relevant in the past few years, as countries develop more cyber weapons and carry out more cyber attacks. The cyber domain has a large scope because of its virtual nature, and it has a high potential threat level as the full impact of cyber capabilities are not even understood yet. As the possibilities for destructive cyber weapons are virtually endless, the threats are also virtually endless. Because of the growing relevance of cyberspace and the high danger level, deterrence thresholds are a pressing issue in this domain. …


Us Blindness To Russian, Chinese Cultural Motives Risks Nuclear Escalation And Ill-Fit Response, Ryan C. Bushman Oct 2023

Us Blindness To Russian, Chinese Cultural Motives Risks Nuclear Escalation And Ill-Fit Response, Ryan C. Bushman

Space and Defense

Student Contribution.

This paper was authored prior to the 2022 Russian invasion of Ukraine and the publication of the 2022 Nuclear Posture Review.

The United States has taken numerous miscalculated steps with respect to foreign and nuclear policy based on an incomplete understanding of the motives of both China and Russia. This is, in part, due to a failure to acknowledge these nations' strategic culture - an enduring system of values that influence a nation's use of military force. As the US is about to put forth its 2022 Nuclear Posture Review (NPR), it is critical that future responses to …


Keynote Address: Dr. Kori Schake, Kori Schake Oct 2023

Keynote Address: Dr. Kori Schake, Kori Schake

Space and Defense

2022 United Sates Strategic Command Academic Alliance Conference and Workshop, Mark 30-April 1, 2022, Conducted via Zoom


Addressing The American Approach To Emerging Technologies: Utilizing The Ai Arms Race To Highlight The Need To Develop Public-Private Partnerships In C4isr And 5g, Hugh Harsono, Nicholas Ondovcsik Oct 2023

Addressing The American Approach To Emerging Technologies: Utilizing The Ai Arms Race To Highlight The Need To Develop Public-Private Partnerships In C4isr And 5g, Hugh Harsono, Nicholas Ondovcsik

Space and Defense

he world of emerging technologies has changed countries' access and placement to these digital enablement tools of the future, with blockchain, decentralization, and a myriad of other compounding technologies accelerating the pace of development and growth combining the physical and the digital world. Historically, America's Silicon Valley has led the world's development of new technologies, particularly during the latter part of the digital revolution. In contrast, China focused on enhancing its manufacturing capabilities, becoming a world leader by capitalizing on the ever-connected world and leveraging its economic prowess. These roles became reversed in the early-2000s,1 when China first surpassed the …


Technology: The Air And Space Force's Barrier To Innovation, William F. Cosgrove Oct 2023

Technology: The Air And Space Force's Barrier To Innovation, William F. Cosgrove

Space and Defense

The Department of Defense is a rank-and-file institution that values orders adherence and a zero-error mentality, which has led commanders to be risk averse. This is exemplified in the cybersecurity realm, with controls attempting to protect all information, including uncontrolled unclassified information. Efforts that attempt to employ a new or different type of information technology are made very difficult by a number of existing policies. Additionally, customer surveys, service initiatives, and open user complaints have revealed dissatisfaction with Department of the Air Force (DAF) IT services. The millennial and post-millennial generations are the most technologically adept, yet the majority of …


A Great Nuclear Rejuvenation: What China Can Do With An Expanded Nuclear Arsenal, Grant Van Robays, Chloe Reynolds, Will Jackson, Tom Hammerle Oct 2023

A Great Nuclear Rejuvenation: What China Can Do With An Expanded Nuclear Arsenal, Grant Van Robays, Chloe Reynolds, Will Jackson, Tom Hammerle

Space and Defense

China's hypersonic glide vehicle test in October 2021 prompted widespread concern in the general public and within the defense intelligence community. General Mark A. Milley, Chairman of the Joint Chiefs of Staff, said the test was "very close" to a Sputnik moment.1 More than mere power projection by the People's Republic of China (PRC) and Chinese Communist Party ( CCP), the hypersonic test is an exemplification of rapid advancements in Chinese strategic nuclear forces writ large. Improved nuclear weapons capabilities will offer Beijing greater leverage in regional and international disputes with an increased capacity to coerce and compel adversaries into …


Editor's Note, Michelle Black Oct 2023

Editor's Note, Michelle Black

Space and Defense

No abstract provided.


Table Of Contents, Space And Defense Oct 2023

Table Of Contents, Space And Defense

Space and Defense

Table of contents for Volume 14 issue 1 of Space and Defense


Front Matter, Space And Defense Oct 2023

Front Matter, Space And Defense

Space and Defense

No abstract provided.


How Education Sats Started & A Youth Amsat-Na Program Proposal, Robert J. Twiggs, Nick Pugh Oct 2023

How Education Sats Started & A Youth Amsat-Na Program Proposal, Robert J. Twiggs, Nick Pugh

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "How Education Sats Started & A Youth Amsat-NA Program Proposal" from October 21, 2023.


Uas Risk Analysis In And Around Airports, Prasad Pothana, Jack Thornby, Michael Ullrich, Sreejith Vidhyadharan, Paul Snyder Oct 2023

Uas Risk Analysis In And Around Airports, Prasad Pothana, Jack Thornby, Michael Ullrich, Sreejith Vidhyadharan, Paul Snyder

Petroleum Engineering Posters and Presentations

No abstract provided.


Stability Of Deep Neural Networks For Feedback-Optimal Pinpoint Landings, Omkar S. Mulekar, Hancheol Cho, Riccardo Bevilacqua Oct 2023

Stability Of Deep Neural Networks For Feedback-Optimal Pinpoint Landings, Omkar S. Mulekar, Hancheol Cho, Riccardo Bevilacqua

Student Works

The ability to certify systems driven by neural networks is crucial for future rollouts of machine learning technologies in aerospace applications. In this study, the neural networks are used to represent a fuel-optimal feedback controller for two different 3-degree-of-freedom pinpoint landing problems. It is shown that the standard sum-ofsquares Lyapunov candidate is too restrictive to assess the stability of systems with fuel-optimal control profiles. Instead, a parametric Lyapunov candidate (i.e. a neural network) can be trained to sufficiently evaluate the closed-loop stability of fuel-optimal control profiles. Then, a stability-constrained imitation learning method is applied, which simultaneously trains a neural network …


State Space Modeling And Estimation Of Flexible Structure Using The Theory Of Functional Connections, Carlo Lombardi, Riccardo Bevilacqua Oct 2023

State Space Modeling And Estimation Of Flexible Structure Using The Theory Of Functional Connections, Carlo Lombardi, Riccardo Bevilacqua

Student Works

In this work, we present a novel method to model the dynamics of a continuous structure based on measurements taken at discrete points. The method is conceived to provide new instruments to address the problem of flexible dynamics modeling in a spacecraft, where an effective mathematical representation of the non-rigid behavior of the is of critical importance in the design of an effective and reliable attitude estimation and control system. Both the measurements and the model that describes the structure can be affected by uncertainty. The purpose of the developed method is to estimate the position and the velocity of …


Using Machine Learning To Predict Hypervelocity Fragment Propagation Of Space Debris Collisions, Katharine Larsen, Riccardo Bevilacqua Oct 2023

Using Machine Learning To Predict Hypervelocity Fragment Propagation Of Space Debris Collisions, Katharine Larsen, Riccardo Bevilacqua

Student Works

The future of spaceflight is threatened by the increasing amount of space debris, especially in the near-Earth environment. To continue operations, accurate characterization of hypervelocity fragment propagation following collisions and explosions is imperative. While large debris particles can be tracked by current methods, small particles are often missed. This paper presents a method to estimate fragment fly-out properties, such as fragment, velocity, and mass distributions, using machine learning. Previous work was performed on terrestrial data and associated simulations representing space debris collisions. The fragmentation of high-velocity fragmentation can be modeled by terrestrial fragmentation tests, such as static detonations. Recently, stereoscopic …


A Holistic Approach To Include Sic And Design The Optimal Extrudate Catalyst For Hydrogen Production–Reforming Routes, Ali M. Alkadhem, Fernanda Tavares, Natalia Realpe, Gontzal Lezcano, Arief Yudhanto, Mohammad Subah, Vasco Manaças, Jacek Osinski, Gilles Lubineau, Pedro Castaño Oct 2023

A Holistic Approach To Include Sic And Design The Optimal Extrudate Catalyst For Hydrogen Production–Reforming Routes, Ali M. Alkadhem, Fernanda Tavares, Natalia Realpe, Gontzal Lezcano, Arief Yudhanto, Mohammad Subah, Vasco Manaças, Jacek Osinski, Gilles Lubineau, Pedro Castaño

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Reforming processes are the backbone of hydrogen production routes, given the flexibility of their feedstock, such as methane, carbon dioxide, ammonia, waste plastics, or biomass. Heat transfer is a drawback at the industrial scale, reducing efficiency. We incorporate SiC in the technical composite, extrudate catalyst and develop a holistic approach to optimize and understand the effect of each constituent and its mixtures. We apply Ni-Ce as an active phase, bentonite or kaolin as a binder, alumina as a filler, and carborundum as the heat-transport carrier. We characterize the extrudate catalysts using various techniques, including crushing strength and thermal conductivity. We …


Atomic Insights Into The Structural Properties And Displacement Cascades In Ytterbium Titanate Pyrochlore (Yb2ti2o7) And High-Entropy Pyrochlores, M. Mustafa Azeem, Qingyu Wang Oct 2023

Atomic Insights Into The Structural Properties And Displacement Cascades In Ytterbium Titanate Pyrochlore (Yb2ti2o7) And High-Entropy Pyrochlores, M. Mustafa Azeem, Qingyu Wang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Pyrochlore oxides ((Formula presented.) are potential nuclear waste substrate materials due to their superior radiation resistance properties. We performed molecular dynamics simulations to study the structural properties and displacement cascades in ytterbium titanate pyrochlore ((Formula presented.)) and high-entropy alloys (HEPy), e.g., (Formula presented.), (Formula presented.), and (Formula presented.). We computed lattice constants (LC) ((Formula presented.)) and threshold displacement energy (Ed). Furthermore, the calculation for (Formula presented.) and ionic radius ((Formula presented.)) were performed by substituting a combination of cations at the A and B sites of the original pyrochlore structure. Our simulation results have demonstrated that the lattice constant is …


Communicating The Need To Communicate - Lessons Learned From Failure Point To A Need For Systems Perspectives, Calvin J. Fong, Elizabeth Matranga, Dianne J. Deturris Oct 2023

Communicating The Need To Communicate - Lessons Learned From Failure Point To A Need For Systems Perspectives, Calvin J. Fong, Elizabeth Matranga, Dianne J. Deturris

College of Engineering Summer Undergraduate Research Program

Failure investigation reports indicate that a systems perspective is needed to reduce failure in aerospace missions.

The failures occurred not because of a technical problem but because not enough communication was occurring.


Additive Manufacturing And Characterization Of Auxetic Structures, Jayesh P. Moore, Stephanie R. Ruzicka Oct 2023

Additive Manufacturing And Characterization Of Auxetic Structures, Jayesh P. Moore, Stephanie R. Ruzicka

College of Engineering Summer Undergraduate Research Program

An auxetic structure is an arrangement of unit cells that under a uniaxial load experiences expansion in both the longitudinal and transverse directions, resulting in a negative Poisson’s ratio (NPR). Research in auxetics has led to new insights into how non-linear mechanical reactions can be applied to various engineering fields. This project utilized stereolithography (SLA) 3D printing to manufacture auxetic test specimens to analyze of geometry-driven NPRs. With the distinctive mechanical properties of auxetic structures and vast applications, the future of product development of these geometries seems promising.


Hardware-In-The-Loop Reaction Wheel Testbed With Camera Vision, Abigail Romero, Harvey Perkins, Stephen Kwok-Choon Oct 2023

Hardware-In-The-Loop Reaction Wheel Testbed With Camera Vision, Abigail Romero, Harvey Perkins, Stephen Kwok-Choon

College of Engineering Summer Undergraduate Research Program

Reaction wheels are widely used in aerospace systems as a method of attitude control. This research was focused on the design, development, and testing of a hardware-in-the-loop reaction wheel testbed that can be used for research and teaching applications related to satellite navigation and control. This project successfully utilized commercial off-the-shelf components to develop a reaction wheel capable of controlling the orientation of a freely rotating platform, as well as tracking objects using computer vision.