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Dissertations / Theses on the topic 'Aerospace engineering, n.e.c'

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Published: 10 December 2022
Last updated: 28 January 2023

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1

Bejarano, Roberto Villa. "An Investigation Into| I) Active Flow Control for Cold-Start Performance Enhancement of a Pump-Assisted, Capillary-Driven, Two-Phase Cooling Loop II) Surface Tension of n-Pentanol + Water, a Self-Rewetting Working Fluid, From 25 ?C to 85 ?C." Thesis, University of Nevada, Reno, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1565813.

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Cold-start performance enhancement of a pump-assisted, capillary-driven, two-phase cooling loop was attained using proportional integral and fuzzy logic controls to manage the boiling condition inside the evaporator. The surface tension of aqueous solutions of n-Pentanol, a self-rewetting fluid, was also investigated for enhancing heat transfer performance of capillary driven (passive) thermal devices was also studied. A proportional-integral control algorithm was used to regulate the boiling condition (from pool boiling to thin-film boiling) and backpressure in the evaporator during cold-start and low heat input conditions. Active flow control improved the thermal resistance at low heat inputs by 50% compared to the baseline (constant flow rate) case, while realizing a total pumping power savings of 56%. Temperature overshoot at start-up was mitigated combining fuzzy-logic with a proportional-integral controller. A constant evaporator surface temperature of 60°C with a variation of ±8°C during start-up was attained with evaporator thermal resistances as low as 0.10 cm2–K/W. The surface tension of aqueous solutions of n-Pentanol, a self-rewetting working fluid, as a function of concentration and temperature were also investigated. Self-rewetting working fluids are promising in two-phase heat transfer applications because they have the ability to passively drive additional working fluid towards the heated surface; thereby increasing the dryout limitations of the thermal device. Very little data is available in literature regarding the surface tension of these fluids due to the complexity involved in fluid handling, heating, and experimentation. Careful experiments were performed to investigate the surface tension of n-Pentanol + water. The concentration and temperature range investigated were from 0.25%wt. to1.8%wt and 25°C to 85°C, respectively.

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2

Phillips, David. "Analysis and Parameter Estimation of the Aerodynamic and Handling Qualities of the C-130A Modified With Wing Tip Tanks." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-11302004-185835/.

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This work presents the background, flight testing, and resulting change in the aerodynamic and handling qualities of a C-130A Hercules modified with wing tip tanks. The data collected during the baseline and modified flight tests of this aircraft demonstrated the potential aerodynamic benefits of a tip tank design that incorporates a greater aspect ratio and end plating effects. Wing mounted pressure belts measured a 24% increase in local Cl near the tip tanks. This local increase in lift contributed to a 38% increase in CL max for the airplane. The pressure and dynamic data was gathered using a LIFT (Linux In Flight Testing) system, and it laid the foundation for finding the longitudinal and lateral directional stability coefficients of the airplane. Then using MATLAB® and the System IDentification Programs for AirCraft (SIDPAC) to reduce this data, it was possible to generate aerodynamic, lateral, and longitudinal parameters that clearly proved the overall benefits of the design change. The demonstrated lift benefits of these uniquely designed tip tanks for the C-130A cargo transport proved that by capitalizing on the benefits of a combination tip tank and end plate design it is possible to generate increased lift without adversely affecting the stability and dynamic parameters of the aircraft.
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3

He, Jiliang. "Silyhydrazines : chemistry and pyrolytic conversion to Si-N-C ceramic materials." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29044.

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A new synthetic route to silylhydrazine molecules and polymers has been developed by the heterodehydrocoupling of organosilanes with hydrazines. A dimethyltitanocene catalyst has been employed to facilitate the dehydrocoupling reaction. The dehydrocoupling was shown to proceed by stepwise replacement of Si-H with hydrazino groups. The controlled hydrolysis of Ph$ sb2$Si(NHNHMe)$ sb2$ formed a hydrazinodisiloxane. Cyclizations of Ph$ sb2$Si(NHNHMe)$ sb2$ to form cyclic silylhydrazines were achieved by the reaction with n-BuLi/Ph$ sb2$SiCl$ sb2,$ or MeI (or HCl or Ph$ sb2$SiCl$ sb2),$ or thermolysis. Crystal structures of Ph$ sb2$Si(NHNR)(NRNH)SiPh$ sb2$ (R = H, Me) reveal chair (R = H) and twist-boat (R = Me) conformations of the Si$ sb2$N$ sb4$ ring, respectively. Planar and pyramidal nitrogen geometries were found to coexist in a hydrazino unit. A preceramic polymer, synthesized by the polymerization of MeHSiCl$ sb2$ with hydrazine in an appropriate ratio, was pyrolyzed to Si$ sb3$N$ sb4$/SiC$ rm sb{x}$N$ rm sb{y}$ in 67-80% ceramic yields. It is proposed that the structural unit of this polymer is a tetraazadisilacyclohexane bridged by MeHSi groups. This assignment is based on $ sp{1}$H and $ sp{29}$Si NMR measurements, as well as by comparison with the well-defined reaction product of Me$ sb2$Si(NHNH) $ sb2$SiMe$ sb2$ with MeHSiCl$ sb2.$ The pyrolysis was carried out from room temperature to 1500$ sp circ$C under argon and studied by using thermogravimetric analysis, solid-state $ sp{29}$Si NMR spectroscopy, infrared spectroscopy, x-ray powder diffraction, and elemental analysis. Serial structural changes were characterized in the pyrolyzed solid products. The ceramic product of this polymer at 1100$ sp circ$C was found to possess a quasi-metallic electrical conductivity ($ sigma$ = 10$ sp3$ ($ Omega$cm)$ sp{{-}1}),$ and was evaluated as an electrode material.
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4

McAvoy, Camille Z. "Palladium-catalyzed C-N cross-coupling reactions toward the synthesis of drug-like molecules." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73388.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Chemistry; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. ).
The development of methodologies for C-N bond formation reactions is an important scientific challenge because of many academic and industrial applications. This work will focus particularly on palladium-catalyzed cross-couplings of amine-containing compounds with aryl halides. The scope of the BrettPhos precatalyst for the cross-coupling of ortho-substituted aryl iodides with amides is studied using substrates with a variety of functional groups. Due to potential metal-chelating issues with some of the substrates used in this study, a proposed ligand synthesis is discussed in which one of the methoxy groups of BrettPhos is replaced with a morpholine capable of occupying palladium's open coordination site during its catalytic cycle. A final C-N bond formation study focuses on the cross-coupling of aryl halides with amidine salts. For this cross-coupling, a methodology has been developed that can be applied to various electron-rich, electron-poor, and electron-neutral substrates. Furthermore, the products of this cross-coupling can be used for a subsequent electrocyclization through a reaction with aldehyde, demonstrating that a relatively simple two-pot methodology can be used to make relatively complex substrates with pharmaceutical applications. Both amides and amidines are common moieties in drug-like molecules because of the various biological activities of these functional groups. Potential medicinal applications of the developed cross-coupling of amidine salts with aryl halides methodology are described. Thus, methodologies for various palladium-catalyzed, C-N cross-couplings as well as a potential ligand synthesis to be used for palladium catalysis are herein discussed.
by Camille Z. McAvoy.
S.B.
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5

Camardo, Andrew T. "C-JUN N-TERMINAL KINASE INHIBITORY NANOTHERAPEUTICS FOR REGENERATIVE ELASTIC MATRIX REPAIR IN ABDOMINAL AORTIC ANEURYSMS." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1499868307678719.

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6

Shi, Zhangsheng. "Strain engineering of Co-N-C catalyst toward enhancing the HER and ORR electrocatalytic activities." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/207078/8/Zhangsheng_Shi_Thesis.pdf.

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This thesis presents a comprehensive review of practical strategies to enhance the catalytic activity of M-N-C materials. The practical strategies can be extended to engineer external factors to break the linear scaling relationships and to further enhance the catalytic performances. In order to design the next-generation higher-performance catalysts, this project was a step forward in developing strain and heterostructure method to achieve a superior HER performance and a ORR performance beyond the limit.
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7

Dong, Jin Xiang 1961. "Effect of silicon on the kinetics of Nb(C,N) precipitation during the hot working of steels." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31048.

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The effect of Si on the kinetics of Nb(C,N) precipitation was investigated by using fractional softening measurements. Compression specimens, with diameters of 7.6 mm and lengths of 11.4 mm, were prepared from four Nb microalloyed steels containing a range of Si concentrations from 0.01 wt% to 0.41 wt%. The stress relaxation method was used in the beginning of this work, but the majority of the experimental results were derived from double-hit compression tests, with a strain of 0.3 applied to represent each pass at a strain rate of 0.1/sec. A solution heat treatment was applied immediately prior to each test.
It was found that the rate of Nb(C,N) precipitation in hot deformed austenite increases with Si concentration. This phenomenon is attributed to the increases in both the Nb diffusivity and the activities of C and N that result from Si addition. Based on the Dutta and Sellars model, an expression for the effect of strain rate on the precipitation start time has been proposed. The present experimental results can then be extrapolated to mill conditions.
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8

Saluru, Deepak Chaitanya. "Active Fault Tolerant Model Predictive Control of a Turbofan Engine using C-MAPSS40k." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338333795.

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9

Robertson, Cole D. "A Computational and Design Characterization for the Flowfield behind a C-130 during an Unmanned Aerial Vehicle Docking." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563533448658585.

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10

Möslinger, Anja. "Particle Trajectory Simulations for SCIENA-N : Conversion surface design for an ENA sensor head." Thesis, Luleå tekniska universitet, Rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-83034.

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This thesis serves as a preliminary design study for the combination of a flight-proven ion optics system (SWIM) with a conversion surface to create a small energetic neutral atom (ENA) sensor. It is planned to use this sensor as ENA sensor for the DFP-SCIENA instrument on Comet Interceptor. Due to the nature of the Comet Interceptor mission (ESA F-class mission with a maximum launch mass of 1000 kg) the development time for a new sensor that meets the size and weight restrictions is limited. The proposed combination of SWIM with a conversion surface is based on a proven ion optics design and should result in a compact sensor design. The main goal of this thesis was to simulate different conversion surface designs and evaluate their compatibility with the SWIM instrument. During this process the different designs were optimised based on the intermediate simulation results. The simulation process was performed by using SIMION to calculate particle trajectories.  In the end, two different conversion surface designs yielded promising results. With both designs detailed simulations and data analysis were conducted to determine the different properties of the two designs. One of these designs was chosen to be further investigated for use on the Comet Interceptor mission.
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11

Rose, Michael Benjamin. "Statistical Methods for Launch Vehicle Guidance, Navigation, and Control (GN&C) System Design and Analysis." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1278.

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A novel trajectory and attitude control and navigation analysis tool for powered ascent is developed. The tool is capable of rapid trade-space analysis and is designed to ultimately reduce turnaround time for launch vehicle design, mission planning, and redesign work. It is streamlined to quickly determine trajectory and attitude control dispersions, propellant dispersions, orbit insertion dispersions, and navigation errors and their sensitivities to sensor errors, actuator execution uncertainties, and random disturbances. The tool is developed by applying both Monte Carlo and linear covariance analysis techniques to a closed-loop, launch vehicle guidance, navigation, and control (GN&C) system. The nonlinear dynamics and flight GN&C software models of a closed-loop, six-degree-of-freedom (6-DOF), Monte Carlo simulation are formulated and developed. The nominal reference trajectory (NRT) for the proposed lunar ascent trajectory is defined and generated. The Monte Carlo truth models and GN&C algorithms are linearized about the NRT, the linear covariance equations are formulated, and the linear covariance simulation is developed. The performance of the launch vehicle GN&C system is evaluated using both Monte Carlo and linear covariance techniques and their trajectory and attitude control dispersion, propellant dispersion, orbit insertion dispersion, and navigation error results are validated and compared. Statistical results from linear covariance analysis are generally within 10% of Monte Carlo results, and in most cases the differences are less than 5%. This is an excellent result given the many complex nonlinearities that are embedded in the ascent GN&C problem. Moreover, the real value of this tool lies in its speed, where the linear covariance simulation is 1036.62 times faster than the Monte Carlo simulation. Although the application and results presented are for a lunar, single-stage-to-orbit (SSTO), ascent vehicle, the tools, techniques, and mathematical formulations that are discussed are applicable to ascent on Earth or other planets as well as other rocket-powered systems such as sounding rockets and ballistic missiles.
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12

Jedrey, Richard M. "Development of a Discretized Model for the Restricted Three-Body Problem." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306856595.

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13

Latif, Shehzad A. "Effects of lightning of low-frequency navigation systems." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1204233932.

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14

Rahil, Issam. "Elaboration et caractérisation de revêtements à base de nitrure de chrome, carbonitrure et carbure de titane élaborés par pulvérisation magnétron." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00967251.

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Le but de ce travail est d'élaborer de nouveaux revêtements anti-usure à base de nitrure de chrome, de carbure et de carbonitrure de titane par dépôt physique en phase vapeur afin d'améliorer la résistance à l'usure à sec des outils de coupe du bois.Des revêtements binaires de CrN et de MoN, ternaires de Cr-Mo-N et de Ti-W-C et quaternaires de Ti-W-C-N ont été déposés sur des outils de coupe en carbure de tungstène et en acier et sur des substrats de silicium par pulvérisation magnétron RF en utilisant différentes cibles (Cr, Mo, Ti et WC) sous différentes atmosphères (Ar, Ar + N2, Ar + CH4 et Ar + N2 + CH4).L'influence de la pression de travail, des ratios des gaz plasmagènes, des tensions d'auto-polarisation des cibles, de la température des substrats et de celle du recuit sur les propriétés des revêtements ont été étudiées, en utilisant l'EDS, la WDS, l'XPS, la DRX, le MEB, le MET, l'AFM, la microscopie optique, l'interférométrie optique (2D et 3D), le Scratch test, l'essai Daimler, la nanoindentation et la tribométrie alternative et rotative. L'objectif est d'établir une corrélation entre le comportement tribologique des revêtements étudiés et leurs propriétés physico-chimiques et mécaniques.Les revêtements optimaux présentant la meilleure résistance à l'usure à sec ont été testés en usinage de l'épinette noire à l'échelle industrielle dans des conditions sévères (-20/-25 °C). Les résultats montrent que grâce à l'emploi des revêtements de Cr-Mo-N, Ti-W-C et de Ti-W-C-N, la durée de vie des outils coupants a été augmentée de 47 à 77 % par rapport à l'outil non revêtu.Mots clés: revêtement, (Cr-Mo)N, (Ti-W)(C,N), propriétés physico-chimiques, propriétés mécaniques, comportement tribologique, usinage bois
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Shohel, Muhammad Shah Newaz. "Panting Fatigue of Welded Steel Tee Details." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220.

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16

Maurer, Andreas. "Methods for Multisensory Detection of Light Phenomena on the Moon as a Payload Concept for a Nanosatellite Mission." Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80785.

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For 500 years transient light phenomena (TLP) have been observed on the lunar surface by ground-based observers. The actual physical reason for most of these events is today still unknown. Current plans of NASA and SpaceX to send astronauts back to the Moon and already successful deep-space CubeSat mission will allow in the future research nanosatellite missions to the cislunar space. This thesis presents a new hardware and software concept for a future payload on such a nanosatellite. The main task was to develop and implement a high-performance image processing algorithm which task is to detect short brightening flashes on the lunar surface. Based on a review of historic reported phenomena, possible explanation theories for these phenomena and currently active and planed ground- or space-based observatories possible reference scenarios were analyzed. From the presented scenarios one, the detection of brightening events was chosen and requirements for this scenario stated. Afterwards, possible detectors, processing computers and image processing algorithms were researched and compared regarding the specified requirements. This analysis of available algorithm was used to develop a new high-performance detection algorithm to detect transient brightening events on the Moon. The implementation of this algorithm running on the processor and the internal GPU of a MacMini achieved a framerate of 55 FPS by processing images with a resolution of 4.2 megapixel. Its functionality and performance was verified on the remote telescope operated by the Chair of Space Technology of the University of Würzburg. Furthermore, the developed algorithm was also successfully ported on the Nvidia Jetson Nano and its performance compared with a FPGA based image processing algorithm. The results were used to chose a FPGA as the main processing computer of the payload. This concept uses two backside illuminated CMOS image sensor connected to a single FPGA. On the FPGA the developed image processing algorithm should be implemented. Further work is required to realize the proposed concept in building the actual hardware and porting the developed algorithm onto this platform.
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17

Soboh, Yousef. "Anaerobic Co-Digestion of Algal Biomass and a Supplemental Carbon Source Material to Produce Methane." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4485.

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Algae that are grown in wastewater treatment lagoons could be an important substrate for biofuel production; however, the low C/N ratio of algae is not conducive to anaerobic digestion of algae with economically attractive methane production rates. Increasing the C/N ratio in anaerobic, laboratory scale, batch reactors by blending algal biomass with sodium acetate resulted i increased methane production rates as the C/N ratio increased. The highest amount of methane was produced when the C/N was 21/1. When the C/N was 24/1, the biogas production rate decreased. Batch experiments were done to evaluate the effect of optimizing the C/N ratio on methane production from algae and to identify the most essential information needed to conduct research on co-digestion of algal biomass using the continuous, high-rate, up-flow anaerobic sludge blanket (UASB) reactor system. Based on the results obtained from batch reactor experiments, anaerobic co-digestion of algal biomass, obtained by continuous centrifugation from the Logan City, Utah, 5th stage wastewater treatment lagoon, and sodium acetate was conducted using laboratory scale UASB reactors with the C/N ratio in the feedstock adjusted to 21/1. Duplicate, 34 L UASB reactor systems were built of poly(methyl methacrylate). Both reactors were seeded with 11 L of anaerobic sediment from the 3rd stage lagoon. The pH of the feedstock was adjusted to the neutral range. The feedstock was initially introduced at a low organic loading rate of 0.9 g/L.d with a hydraulic retention time (HRT) of 7.2 days and then increased up to 5.4 g/L.d and a HRT of 5.5 days. These organic loading rates corresponded to an initial influent chemical oxygen demand (COD) of 6.25 g/L and increased to 27.2 g/L. Methane production increased from 270 mL/g to 349 mL/g COD biodegraded. COD removal efficiency was 80% and biogas methane composition was 90% at steady state. Algal biomass contributed 33-50% of the COD in the feed stock depending on the COD of the algae paste from centrifugation. The shortest HRT at which steady state was not affected was 5.5 days. At lower HRT all monitored parameters showed a slight decrease after the 75th day of operation.
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18

Gruwell, Ammon Bradley. "High-Speed Programmable FPGA Configuration Memory Access Using JTAG." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6321.

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Over the past couple of decades Field Programmable Gate Arrays (FPGAs) have become increasingly useful in a variety of domains. This is due to their low cost and flexibility compared to custom ASICs. This increasing interest in FPGAs has driven the need for tools that both qualify and improve the reliability of FPGAs for applications where the reconfigurability of FPGAs makes them vulnerable to radiation upsets such as in aerospace environments. Such tools ideally work with a wide variety of devices, are highly programmable but simple to use, and perform tasks at relatively high speeds. Of the various FPGA configuration interfaces available, the Joint Test Action Group (JTAG) standard for serial communication is the most universally compatible interface due to its use for verifying integrated circuits and testing printed circuit board connectivity. This universality makes it a good interface for tools seeking to access FPGA configuration memory. This thesis introduces a new tool architecture for high-speed, programmable JTAG access to FPGA configuration memory. This tool, called the JTAG Configuration Manager (JCM), is made up of a large C++ software library that runs on an embedded micro-processor coupled with a hardware JTAG controller module implemented in programmable logic. The JCM software library allows for the development of custom JTAG communication of any kind, although this thesis focuses on applications related to FPGA reliability. The JCM hardware controller module allows these software-generated JTAG sequences to be streamed out at very high speeds. Together the software and hardware provide the high-speed and programmability that is important for many JTAG applications.
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Baalla, Younes. "Development and Use of a Computer Program “Hyper-N” to Predict the Performance of Air Vehicles Traveling at Hypersonic Speeds." 2010. http://trace.tennessee.edu/utk_gradthes/684.

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Abstract The main objective of this thesis was to develop a method than can be used to approximate the pressure forces on air vehicles traveling at hypersonic speed (Mach number > 5). The aerodynamic forces such as lift and drag were calculated from the pressure values on the surface of the airplane. Pitching moment was also tabulated. This work was initiated based on the idea of developing a flow solver proficient and capable of providing aerodynamic data (lift and drag look-up tables) for hypersonic air vehicles that can be fed to a flight simulator (used by the Aviation Systems Department) at the University of Tennessee Space Institute. Several approximation methods are used to solve hypersonic such as shock expansion method. Based on different studies, Computational Fluid Dynamic (CFD) proved to produce very accurate results; however, it is a difficult technique to use. In this thesis work Newtonian Method was adopted as a technique to approximate the aerodynamic forces and hence the performance of hypersonic airplanes, therefore, a computer program (Hyper-N) has been developed for aerodynamic analysis of three dimensional geometries airplane. The program is designed to read in a previously configured list of plates and compute the aerodynamic forces and moments for hypersonic free stream conditions. Programming was completed using MatLab language. The results obtained from the Hyper-N program were for the experimental airplane X-43A which were found to match the results when the shock expansion method is used for the same airplane, [1]. Because of the difficulties involve in using CFD or the complete Navier Stocks equation to obtain the aerodynamic forces on bodies traveling at hypersonic speeds, the Newtonian method is considered to be the most efficient technique to use for preliminary evaluation of the performance of hypersonic airplanes. Modified Newtonian theory and the computational requirement of the code are described. A number of geometric configurations, including the X-43A (experimental hypersonic) airplane, are provided as examples of applications of the Hyper-N program.
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Benaboud, R. "Etude thermodynamique et élaboration de dépôts métalliques (W-N-C, Ti-N-C) par PEALD (Plasma Enhanced Atomic Layer Deposition) pour la réalisation d'électrodes de capacités Métal/Isolant/Métal dans les circuits intégrés." Phd thesis, 2009. http://tel.archives-ouvertes.fr/tel-00441093.

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Les capacités MIM (Métal/Isolant/Métal), au coeur de cette étude, sont des composants intégrés entre les niveaux d'interconnections. Le développement de nouvelle architecture en trois dimensions impose de déposer les films ultraminces constituant la capacité MIM de manière très conforme. Ce qui conduit à utiliser un nouveau procédé de dépôt : la méthode ALD assistée par plasma ou PEALD. De plus l'augmentation des performances électriques des MIM passe par une maîtrise des propriétés des électrodes et des interfaces créées entre le diélectrique et les électrodes métalliques. Les matériaux développés dans cette étude sont Ti- N-C and W-N- C, déposés par PEALD à partir de précurseurs organométalliques TDMAT et BTBMW. Une étude sur les propriétés physico-chimiques et électriques des films est effectuée ainsi que l'intégration de ces films dans les capacités MIM.
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(10587056), Rohan Gajanan Deshmukh. "System Analysis of a Numerical Predictor-Corrector Aerocapture Guidance Architecture." Thesis, 2021.

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Aerocapture has been envisioned as a potential orbit insertion technique for planetary destinations with an atmosphere. Despite not being flight proven technique, many studies found in the literature and recent mission proposals have employed aerocapture into their respective mission designs. The potential varying levels of trajectory dispersions experienced during atmospheric flight at each destination drives the need for robust and fuel-efficient guidance and control solutions. Existing guidance algorithms have relied on tracking precomputed reference trajectories, which are computed using significant simplifications to the flight mechanics, are not generally designed to be fuel-efficient, and require tedious performance gain tuning. When simulated with higher levels of uncertainty, the existing algorithms have been shown to produce large orbit insertion errors. Furthermore, existing flight control methodologies have been limited in scope to bank angle modulation. While some studies have introduced new methodologies, such as drag modulation and direct force control, they haven’t been tested at the same level of rigor as the existing methods. Advances in on-board computational power are allowing for modern guidance and control solutions, in the form of numerical predictor-corrector algorithms, to be realized. This dissertation presents an aerocapture guidance architecture based on a numerical predictor-corrector algorithm. Optimal control theory is utilized to formulate and numerically obtain fuel-minimizing flight control laws for lifting and ballistic vehicles. The unified control laws are integrated into a common guidance algorithm. The architecture is utilized to conduct Monte Carlo simulation studies of Discovery-class and SmallSat-class aerocapture missions at various planetary destinations.

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22

Aswathi, S. "Effective Property Estimation of Carbon Composites using Micromechanical Modeling." Thesis, 2014. http://hdl.handle.net/2005/3196.

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In recent times, composite materials have gained mainstay acceptance as a structural material of choice due to their tailorability and improved thermal, specific strength/stiffness and durability performance. Carbon-Carbon (C/C) composites are used for high temperature applications such as exit nozzles for rockets, leading edges for missiles, nose cones, brake pads etc. Mechanical property estimation of C/C composites is challenging due to their highly heterogeneous microstructure. Computed Tomography (CT) images (volumetric imaging) coupled with Scanning Electron Microscopy (SEM) reveal a highly heterogeneous microstructure comprised of woven C-fibers, amorphous C-matrix, irregularly shaped voids, cracks and other inclusions. The images also disclose structural hierarchy of the C/C composite at different length scales. Predicting the mechanical behavior of such complex hierarchical materials like C/C composites forms the motivation for the present work. A systematic study to predict the effective mechanical properties of C/C Composite using numerical homogenization has been undertaken in this work. The Micro-Meso-Macro (MMM) principle of ensemble averages for estimating the effective properties of the composite has been adopted. The hierarchical length scales in C/C composites has been identified as micro (single fiber with matrix), meso (fabric) and macro (laminate). Numerical homogenization along with periodic boundary conditions (PBCs) have been used to estimate the effective engineering properties of the material at different length scales. Concurrently, mechanical testing has also been carried out at macro (compression tests) and micro scale (using nano-indentation studies) to characterize the mechanical behavior of C/C composites.
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McKenna, Amanda Marie. "Characterizing groundwater-surface water interactions in Great Smoky Mountains National Park using hydrologic, geochemical & isotopic data." 2007. http://etd.utk.edu/2007/McKennaAmanda.pdf.

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(7013471), NIRANJAN RAVI. "Integration of UAVS with Real Time Operating Systems and Establishing a Secure Data Transmission." Thesis, 2019.

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Abstract:
In today’s world, the applications of Unmanned Aerial Vehicle (UAV) systems are leaping by extending their scope from military applications on to commercial and medical sectors as well. Owing to this commercialization, the need to append external hardware with UAV systems becomes inevitable. This external hardware could aid in enabling wireless data transfer between the UAV system and remote Wireless Sensor Networks (WSN) using low powered architecture like Thread, BLE (Bluetooth Low Energy). The data is being transmitted from the flight controller to the ground control station using a MAVlink (Micro Air Vehicle Link) protocol. But this radio transmission method is not secure, which may lead to data leakage problems. The ideal aim of this research is to address the issues of integrating different hardware with the flight controller of the UAV system using a light-weight protocol called UAVCAN (Unmanned Aerial Vehicle Controller Area Network). This would result in reduced wiring and would harness the problem of integrating multiple systems to UAV. At the same time, data security is addressed by deploying an encryption chip into the UAV system to encrypt the data transfer using ECC (Elliptic curve cryptography) and transmitting it to cloud platforms instead of radio transmission.
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