<p> This study proposes that a Boeing X-37B space plane, its dimensions and performance characteristics estimated from publicly available documents, diagrams, and photographs, could be internally redesigned as a medical evacuation (ambulance) vehicle for the International Space Station. As of 2017, there is currently no spacecraft designed to accommodate a contingency medical evacuation wherein a crew member aboard the ISS is injured or ailing and must be returned to Earth for immediate medical attention. The X-37B is an unmanned vehicle with a history of success in both sub-orbital testing and all four of its long-duration orbital missions to date. Research conducted at UC Davis suggests that it is possible to retain the outer mold line of the X-37B while expanding the internal payload compartment to a volume sufficient for a crew of three&mdash;pilot, crew medical officer, and injured crew member&mdash;throughout ISS un-dock and atmospheric entry, descent, and landing. In addition to crew life support systems, this re-purposed X-37B, hereafter referred to as the X-37SA (Space Ambulance), includes medical equipment for stabilization of a patient in-transit. This study suggests an optimal, ergonomic crew configuration and berthing port location, procedures for microgravity ingress and 1G egress, a minimum medical equipment list and location within the crew cabin for the medical care and monitoring equipment. Conceptual crew configuration, ingress/egress procedures, and patient/equipment access are validated via physical simulation in a full-scale mockup of the proposed X-37SA crew cabin.</p><p>

<p> This study contributes to a better understanding of ignition by hot combustion gases which finds application in internal combustion chambers with pre-chamber ignition as well as in wave rotor engine applications. The experimental apparatus consists of two combustion chambers: a pre chamber that generates the transient hot jet of gas and a main chamber which contains the main fuel air blend under study. Variables considered are three fuel mixtures (Hydrogen, Methane, 50% Hydrogen-Methane), initial pressure in the pre-chamber ranging from 1 to 2 atm, equivalence ratio of the fuel air mixture in the main combustion chamber ranging from 0.4 to 1.5, and initial temperature of the main combustion chamber mixture ranging from 297 K to 500 K. Experimental data makes use of 4 pressure sensors with a recorded sampling rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition delay considerably. Physical mixing effects, and density of the main chamber mixture have a greater effect on hot jet ignition delay</p><p>

<p> Bonding composite structures using adhesives offers several advantages over mechanical fastening such as better flow stress, weight saving, improved fatigue resistance and the ability to join dissimilar structures. The hesitation to adopt adhesively bonded composite joints stems from the lack of knowledge regarding damage initiation and propagation mechanisms within the joint. A means of overcoming this hesitation is to continuously monitor damage in the joint. This study proposes a methodology to conduct structural health monitoring (SHM) of an adhesively bonded composite lap joint using acoustic, guided Lamb waves by detecting, locating and predicting the size of damage. Finite element modeling of a joint in both 2D and 3D is used to test the feasibility of the proposed damage triangulation technique. Experimental validation of the methodology is conducted by detecting the presence, location and size of inflicted damage with the use of tuned guided Lamb waves.</p>

<p>The light weight of composite materials has attracted interests to improve fuel economy of aircrafts and to extend flight range. The usage of composite materials is increasing in airframes and other parts of aerospace industry. Although most tests on composites are conducted uniaxially, they are subjected to multi-axial loads in real life applications. Hence, there is a need to better understand the complex failure mechanisms in composite structures. More reliable failure theories and damage progression models should be devised. Also, reliable criteria for predicting failure of fiber composite laminates are necessary for rational analysis and design. In this thesis, the behavior of a symmetric composite material under bi-axial loading is studied and the failure of the composite material is predicted by Yeh-Stratton criterion. A MATLAB program is prepared for the study of failure in tubular specimens composed of AS4/3501-6 carbon/epoxy laminates, which were subjected to internal pressure and axial force simultaneously to vary the states of stress. It is shown that the Yeh-Stratton criterion is in a good agreement with the experimental results. Future work may include collection of more accurate and different kind of experimental data on composite materials and modification of the interaction factor B12 value to evaluate its effect on the theoretical prediction by the Yeh-Stratton criterion. </p>

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: Gary Harlow.

<p> A computer vision-based navigation feasibility study consisting of two navigation algorithms is presented to determine whether computer vision can be used to safely navigate a small semi-autonomous inspection satellite in proximity to the International Space Station. Using stereoscopic image-sensors and computer vision, the relative attitude determination and the relative distance determination algorithms estimate the inspection satellite's relative position in relation to its host spacecraft. An algorithm needed to calibrate the stereo camera system is presented, and this calibration method is discussed. These relative navigation algorithms are tested in NASA Johnson Space Center's simulation software, Engineering Dynamic On-board Ubiquitous Graphics (DOUG) Graphics for Exploration (EDGE), using a rendered model of the International Space Station to serve as the host spacecraft. Both vision-based algorithms proved to attain successful results, and the recommended future work is discussed. </p>

<p> We present the background and motivation for ground vehicle autonomy, and focus on uses for space-exploration. Using a simple design example of an autonomous ground vehicle we derive the equations of motion. After providing the mathematical background for nonlinear systems and control we present two common methods for exactly linearizing nonlinear systems, feedback linearization and backstepping. We use these in combination with three adaptive control methods: model reference adaptive control, adaptive sliding mode control, and extremum-seeking model reference adaptive control. We show the performances of each combination through several simulation results. We then consider disturbances in the system, and design nonlinear disturbance observers for both single-input-single-output and multi-input-multi-output systems. Finally, we show the performance of these observers with simulation results.</p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3120. Adviser: Nancy R. Sottos. Includes bibliographical references (leaves 94-99) Available on microfilm from Pro Quest Information and Learning.

<p> Acceptance of Carbon Fiber Reinforced Polymer (CFRP) structures requires a robust surface preparation method with improved process controls capable of ensuring high bond quality. Surface preparation in a production clean room environment prior to applying adhesive for bonding would minimize risk of contamination and reduce cost. Plasma treatment is a robust surface preparation process capable of being applied in a production clean room environment with process parameters that are easily controlled and documented. Repeatable and consistent processing is enabled through the development of a process parameter window utilizing techniques such as Design of Experiments (DOE) tailored to specific adhesive and substrate bonding applications. Insight from respective plasma treatment Original Equipment Manufacturers (OEMs) and screening tests determined critical process factors from non-factors and set the associated factor levels prior to execution of the DOE. Results from mode I Double Cantilever Beam (DCB) testing per ASTM D 5528 [1] standard and DOE statistical analysis software are used to produce a regression model and determine appropriate optimum settings for each factor.</p>

<p> This thesis presents a mathematical modeling process for characterizing a hyperelastic material with viscous response under dynamic loading conditions. The model is designed with the advantage of performing only one compressive dynamic test in order to provide the requisite parameters to fully determine the hyper-viscoelastic response. This is achieved in both deformations and contact forces, using digital image correlation and force sensors. Experiments performed at strain rates ranging from 10^&ndash;3&ndash;10² s^&ndash;1 correlate with computational simulations at the same loading rates up to 80% compression. The validity of the fit and prediction is assessed using MATLAB along with ABAQUS finite element software. </p><p> The results provided by this novel methodology, i.e. the mathematical model using non-homogeneous deformations and the subsequent dynamic experimental techniques, proves that this approach is a more effective alternative to the current standards used to characterize the mechanical response of hyperelastic, viscoelastic, and hyper-viscoelastic materials.</p><p>