Aerospace Engineering Commons^™

Integral Boundary Layer Methods In Python, Malachi Joseph Edland

Master's Theses

This thesis presents a modern approach to two Integral Boundary Layer methods implemented in the Python programming language. This work is based on two 2D boundary layer methods: Thwaites' method for laminar boundary layer flows and Head's method for turbulent boundary layer flows. Several novel enhancements improve the quality and usability of the results. These improvements include: a common ordinary differential equation (ODE) integration framework that generalizes computational implementations of Integral Boundary Layer methods; the use of a dense output Runge-Kutta ODE solver that allows for querying of simulation results at any point with accuracy to the same order as …

Design, Analysis And Experimental Evaluation Of 3d Printed Variable Stiffness Structures, Rossana R. Fernandes

Doctoral Dissertations and Master's Theses

The rapid progress of additive manufacturing (AM) introduces new opportunities but also new challenges for design and optimization to ensure manufacturability, testability and accurate representation/prediction of the models. The present dissertation builds a bridge between design, optimization, AM, testing and simulation of advanced optimized variable-stiffness structures. The first part offers an insight on the mechanical, viscoelastic and failure characteristics of AM continuous fiber composites. This understanding was used in the second part to investigate the feasibility of different topology and fiber-orientation optimization methods and the manufacturability of the resulting models. The study also assesses the effects of the manufacturing constraints …

Investigation On The Interaction Of An Impinging Jet With Cylinder Wakes, Karthik Krishna

Doctoral Dissertations and Master's Theses

Jet impingement cooling is a widely used cooling method due to the high heat transfer rates associated with it. Research for improving heat transfer rates for this cooling is still being carried out due to its broad application in various fields like gas turbine blade cooling, electronic component cooling, and paper drying. The unsteady jet oscillation effectively enhances the stagnation region and the time-averaged heat transfer rates. It is shown that a novel passive jet oscillation technique can be achieved using the vortices periodically shed from a cylinder placed upstream in a channel with an initial crossflow. Preliminary CFD results …

Navigation Performance Of Line/Plane Intersection Lidar Model In Conjunction With Opportunistic Feature Tracker, Michael R. Hansen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

With NASA awarding numerous contracts to build commercial lunar payload spacecraft and human lunar landers, the need for high precision navigation has increased. Traditional inertial navigation alone is not sufficient to autonomously land a vehicle on hazardous lunar terrain. Terrain relative navigation (TRN) systems have been explored in previous research that exploit camera observations of known landmarks. Such approaches require the flight electronics to correctly match features of the observed landmarks to an onboard database, in the drastically varying lighting conditions of moon. This paper explores the performance of a TRN system that does not rely on apriori landmark identification, …

3d-Printed Morphing Wings For Controlling Yaw On Flying-Wing Aircraft, Benjamin C. Moulton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The flaps on an airplane wing are used to control the aircraft during flight. These flaps traditionally have at most three articulation or hinge points. Recent studies have shown improved flap efficiency using a conformal flap, which deforms following a curved shape. Much of aircraft improvement comes through increasing its efficiency during flight. This efficiency is generally improved by decreasing the drag force on the aircraft. A potential solution to decrease drag is to remove additional lifting surfaces, such as the horizontal and vertical stabilizer ubiquitous on general aviation aircraft. These additional lifting surfaces are used to trim and control …

Attitude And Reflection Parameter Estimation Of Resident Space Objects Using Ground-Based Photometry, Arun J. Bernard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

There are currently thousands of objects orbiting Earth, and this number is only going to increase. Larger number of satellites will require that operators have a greater knowledge of the state their assets. Electro-optical telescopes are currently being used to observe and track many of these objects. When using these telescopes to take images of satellites, they often appear as dots in the image. Depending on the surface properties of the satellite, and its orientation at a given time, the dots in the image can appear brighter or dimmer. Photometry measurements are a quantification of how bright the object appears. …

Passive Cavity Deflation After Water Entry Facilitated By A Vented Tube, Emma R. Fraley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

When an object enters water, a crater, or air cavity, can form around the object and remain attached as the object travels underwater. Cavities can be beneficial and reduce drag force but there may be times when the cavity needs to be removed. This research proposes a method to remove air cavities by letting air leave the cavity, deflating the cavity similar to how a balloon is deflated. To provide air a path to leave the cavity, a tube with vent holes is attached to the object. The vent holes are located near the object, where the air cavity forms, …

Exact And Approximate Relaxation Techniques For Computational Guidance, Sheril Avikkal Kunhippurayil

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this dissertation is in the development and application of relaxation techniques that enable efficient and real-time solution of complex computational guidance problems. Relaxations transform a non-convex constraint into a convex constraint and provides proof that the optimal solutions to the relaxed problem are optimal for the original problem. Unique contributions of this work include: 1) a relaxation technique for solving fixed final time problems between fixed points, 2) a performance analysis on the application of computational guidance for the Mars Ascent Vehicle, and 3) establishment of sufficient conditions for non-singularity of optimal control for problems on a …

Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The radiative transfer equation (RTE) is strongly coupled to the material response code KATS. A P-1 approximation model of RTE is used to account for radiation heat transfer within the material. First, the verification of the RTE model is performed by comparing the numerical and analytical solutions. Next, the coupling scheme is validated by comparing the temperature profiles of pure conduction and conduction coupled with radiative emission. The validation study is conducted on Marschall et al. cases (radiant heating, arc-jet heating, and space shuttle entry), 3D Block, 2D IsoQ sample, and Stardust Return Capsule. The validation results agree well for …

Effects And Solutions On The Human Body After Long-Duration Space Flights, Jose Jaime Esquivel Patricio

McNair Research Journal SJSU

During the Cold War, President John F. Kennedy made it a mission for the National Aeronautics and Space Administration (NASA) to accomplish a lunar landing and return to Earth. The final lunar landing and the last time humans left Low Earth Orbit (LEO) was in December, 1972. However, 47 years have passed and the fascination with traveling into deep space remains alive and flourishing. A major problem with future human missions to Mars is the effects of microgravity and Mars’ 0.38g environment. Unfortunately, space medicine is limited and little is known about the effects of microgravity on the human body …

Issue 9: Contributors, D. Flournoy, Randall Johnson

Online Journal of Space Communication

List of issue 9 contributors.

Gps & Galileo: Prospects For Building The Next Generation Of Global Navigation Satellite Systems, Glen Gibbons Jr.

Online Journal of Space Communication

In the next 5 to 10 years, the world will experience the emergence of a true Global Navigation Satellite System (GNSS) - a compatible and, in many respects, interoperable system of systems. The U.S. Global Positioning System, Europe's Galileo, perhaps Russia's Glonass system, and regional augmentations including the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), radiobeacon-based systems such as the U.S. Nationwide Differential GPS, and compatible commercial differential correction services will comprise this multifaceted GNSS. Common signal structures and frequency plans will enable combined user equipment that reduces the technical complexity and cost, while vastly …

New U.S. Gps Policy From A European Perspective, Martin U. Ripple, Alexis Vidal

Online Journal of Space Communication

On December 8, 2004, the President of the United States of America authorized the new U.S. Space-based Positioning, Navigation and Timing Policy. This new policy sets forth a forward-looking framework for the management of GPS and its augmentations. In particular, the new U.S. policy mentions interaction with other satellite navigation systems.

Following the establishment of a U.S.-E.U. framework agreement for cooperation between GPS and Galileo, signed on June 26, 2004, European policy makers and industrialists expected clear statements on cooperation and interoperability issues from the new U.S. GPS policy. Regrettably, the related recommendations hold short of the need for cooperation …

Receiver Performance For An Enhanced Dgps Data Channel, Gregory Johnson, Michael Kuhn, Peter F. Swaszek, Richard Hartnett, Per Enge

Online Journal of Space Communication

The Coast Guard currently operates a maritime differential GPS service consisting of two control centers and over 85 remote broadcast sites. This service broadcasts GPS correction information on marine radiobeacon frequencies to improve the accuracy and integrity of GPS. The existing system provides differential corrections over a medium frequency carrier using minimum shift keying (MSK) as the modulation method. MSK is a version of the Continuous Phase Frequency Shift Keying (CPFSK) modulation technique that is "spectrally compact," meaning that it is a narrow band modulation scheme. In a binary signaling channel, the two instantaneous frequencies for this modulation method are …

Space Based Real-Time Kinematic Gps For National Geodetic Survey Texas Height Modernization, S. D. Lyle, D. M. Mulcare

Online Journal of Space Communication

Height Modernization is a program in NOAA's National Geodetic Survey (NGS) that uses the Global Positioning System (GPS) and other new technologies to increase the accuracy of elevation measurements that comprise the vertical portion of the National Spatial Reference System (NSRS). Height Modernization Program within NGS is working with states to improve the height component of their survey control networks and related products. Texas A&M University- Corpus Christi (A&M-CC) was designated as the recipient of a grant under the Program during the most recent Congressional cycle. In order to best coordinate and manage the activities funded by the grant, A&M-CC …

Sea Surface Wave Information Using Gps Sea Reflected Signal - Wave Height, Shigeyuki Okuda, Yasuo Arai, Nobuyoshi Kouguchi

Online Journal of Space Communication

In case of positioning by GPS, the direct signal from the satellite to the receiver is ordinarily utilized, but the multipath signal is regarded as one error source that deteriorate the positioning accuracy. In this paper, we focus on characteristics of the reflected signal, and had a few simulation tests. The correlator output signals are checked out and compared to the change of wave height and the wave period.

In this paper we describe that in sufficient long wave compared with reflection area size we can measure an accurate wave height, and by pointing antenna beam center from two directions …

Moving Map And Situational Awareness Capabilities Of The Dagr, Gary L. Bachman

Online Journal of Space Communication

This paper presents an overview of the Moving Mapp and Situational Awareness capabilities of the Defense Advanced GPS Receiver (DAGR) military handheld GPS receiver (refer to Figure 1), and how these capabilities can be utilized for other applications. The paper first presents an overview of situational awareness and moving maps as provided by handheld GPS receivers, factors driving the DAGR's requirements, and the requirements themselves.

This paper presents the system design in a two-part approach corresponding to the two primary components of the system: 1) importing digital map products into the DAGR and 2) displaying moving maps and situational awareness …

Egnos Terrestrial Regional Augmentation Networks Based On Ais For River Information Services, M. Jandrisits, J. C. De Mateo, G. Abwerzger

Online Journal of Space Communication

Within the ESA Advanced Research Telecommunications program ARTES-5, the project GALEWAT (Galileo and EGNOS for Waterway Transport) aims at introducing EGNOS into River Information Services (RIS) through the Automatic Identification System (AIS), a link that is mandatory for seagoing vessels above 300 GT.

The GALEWAT project comprises several phases: During the initial definition phase, the system architecture and user equipment have been defined in line with standards and international recommendations. This phase was followed by the implementation phase, aiming at developing and setting up the equipment. Finally, the project will be completed by an extensive demonstration phase, which is currently …

Geosynchronous Satellite Use Of Gps, Jennifer L. Ruiz, Charles H. Frey

Online Journal of Space Communication

The purpose of this study was to determine the accuracy of GPS use for a geosynchronous (GEO) satellite. Current missions at GEO altitude mainly use traditional ranging for orbit determination. With changing mission requirements and the increase in the number of GEO missions, utilizing GPS signals is becoming an increasingly attractive alternative for position and timing determination. A previous ION paper discusses the use of GPS data for a particular geosynchronous satellite mission and is included here as a reference. GPS use at GEO is primarily limited by the availability of the spillover from the GPS earth coverage signal. The …

Galileo In Bavariansky - Network Of Excellence In Satellite Navigation, Bärbel Deisting

Online Journal of Space Communication

The building up of the European satellite navigation system Galileo with its new services, the guaranteed reliability and continuity as well as the interoperable and complementary relation to GPS is expected to open new markets for satellite navigation applications all over the world. Many sectors will benefit from Galileo as the range of application is varied and an exponential grow is being expected for fields related to the development of satellite navigation.

During the last years several examinations dealing with satellite navigation sector in Bavaria have been carried out. The analyses revealed that satellite navigation signals serve as basis for …