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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

ACTS Propagation Experiment and Solar/Lunar Intrusions

Gardner, Christopher S. 10 1900 (has links)
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / In this paper are described the effects that solar and lunar intrusions have on statistical analysis of the data. The NASA ACTS experiment focuses on the 20 and 27 GHz radiometer and beacon. The experiment is currently compiling a database for the attenuation for these different channels. For the year of 1994 our sight obtained 86.5 hours of attenuation and for 1995 our sight obtained 77 hours of attenuation. The total amount of interference time for sun/lunar intrusions for 1994 and 1995 was respectively, 39 hours and 38.5 hours, which is nearly half the total amount of attenuation due to rain and cloud fades. It is clear to see why this data must be taken out for any type of statistical analysis of the data.
22

Link Validation and Performance Measurement within the NASA Space Network

Puri, Amit, Lokshin, Kirill, Tao, Felix, Cunniff, David, Glasscock, David, Ramlagan, Raj 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / The National Aeronautics and Space Administration (NASA) Space Network (SN) consists of a Space Segment, composed of the Tracking and Data Relay Satellite (TDRS) fleet, and a Ground Segment that includes the White Sands Ground Terminal (WSGT), Second TDRS Ground Terminal (STGT) and the Guam Remote Ground Terminal (GRGT). Collectively, the SN Ground Segment is commonly referred to as the White Sands Complex (WSC). Traditional methods of latency and performance measurement across the component links of network have relied on the use of simplified test patterns and basic data formats that are often specific to the instruments providing the measurements. These tests do not often correlate to the operational data normally transferred through the network. This paper discusses an alternative approach to performance measurement within the Space Network. By embedding and extracting performance metrics directly within simulated data sets that closely resemble operational traffic, performance measurement can be combined with link verification and validation to provide a single, comprehensive set of test and measurement activities.
23

Applications of Acoustic Techniques to Targeting Drug Delivery and Dust Removal Relevant to NASA Projects

Chen, Di 18 November 2010 (has links)
Sonoporation, enhanced by ultrasound contrast agents has been explored as a promising non-viral technique to achieve gene transfection and targeting drug delivery in recent years. However, the short lifespan of traditional ultrasound contrast agents like Optison® microbubbles under moderate intensity ultrasound exposure limits their application. Liposomes, as drug carriers consisting of curved spherical closed phospholipid bilayer shells, have the following characteristics: 1) The ability to encapsulate and carry hydrophilic or hydrophobic molecules. 2) The biocompatibility with cell membranes. 3) The nanometer size and the relative ease of adding special ligands to their surface to target a specific disease site. 4) The stability in the blood stream. 5) Targeted ultrasound irradiation can induce rupture of liposomes letting the drug encapsulated in them leak out to achieve controlled release of the therapeutic agents at a certain concentration and a delivery rate. In this thesis, several liposome synthesis methods are presented. Liposomes synthesized in our laboratory were characterized acoustically and optically. Anti rabbit IgG conjugated with Alexafluor 647 was delivered into Jurkat cells in a suspension containing liposomes by 10 % duty cycle ultrasound tonebursts of 2.2 MHz (the in situ spatially averged and temporally averaged intensity, ISATA = 80W/cm2) with an efficiency of 13 %. It has been experimentally shown that liposomes may be an alternative stable agent to Optison® to cause sonoporation. Furthermore, a type of nanometer-sized liposome (<300nm) was synthesized to explore the feasibility of ultrasound-triggered release from drug encapsulated lipsomes. It has been demonstrated encapsulated fluorescence materials (FITC) can be released from liposomes with an average diameter of 210 nm when exposed to high intensity focused ultrasound (HIFU) at 1.142MHz (ISPTA= 900 W/cm2). Rupture of relatively large liposomes (>100nm) and porelike defects in the membrane of small liposomes due to the excitation of HIFU were the main causes of the content release. The great enhancement of HIFU-mediated release in the nanometer-sized liposomes may prove useful for clinical applications. The presence of fine particles in Martian and lunar soil poses a significant threat to NASA’s viable long-term exploration and habitation of either the moon or Mars. It has been experimentally shown that the acoustic levitating radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture acoustic tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. The majority of fine particles (> 2μm diameter) on a reflector surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. This dust removal technique may be used in space-stations or other enclosures for habitation.
24

Variation de prise en charge des patients : discrimination dans les soins et/ou charge de travail élevée / Differences in care : discrimination in care and/or high workload

Schoenenberger, Sandrine 15 May 2012 (has links)
Les études françaises sur la discrimination en milieu médical s’intéressent aux refus de soins des libéraux selon le système d’assurance des patients. Les recherches anglo-saxonnes examinent les différences de prises en charge sous l’angle de l’ethnie du patient. Burgess (2010) suggère que les discriminations en milieu médical peuvent être plus fréquentes lorsque le soignant est placé sous un niveau élevé de charge cognitive. Les recherches dans le domaine de la psychologie du travail et l’ergonomie indiquent que dans les cas de surcharge de travail, l’opérateur modifie son activité. Les comportements qualifiés de discriminatoires pourraient alors être le résultat des mécanismes de régulation de la charge de travail. Deux vagues d’entretiens auprès de soignants (N = 22 pour la première étude et N = 6 pour la seconde) indiquent un lien de leur part entre discrimination et charge de travail. Les observations menées en milieu hospitalier et couplées à un questionnaire et le NASA-TLX (N = 121) ont permis de constater que les discriminations en milieu médical sont faibles. Elles concernent uniquement la dimension relationnelle, les actes médicaux (examens, soins) sont réalisés normalement. Les variations constatées dans les comportements des soignants adviennent à l’encontre de patients stigmatisés et difficiles à gérer. / The French studies about discrimination in medical settings are focused on the general practitioners’ refusal to provide care depending on the patient’ insurance cover. Anglo-Saxon research examines the differences in care according to the patient’s ethnicity. Burgess (2010) suggests that discriminations in healthcare settings may happen more frequently when health care providers are put under high levels of cognitive load. Research in the fields of occupational psychology and ergonomics indicates that in cases of work overload, workers change their activity. Behavior described as discriminatory might result from regulation mechanisms of work overload regulation mechanisms. Two waves of interviews with healthcare providers (N = 22 for the first time and N = 6 for the second time) point to a link between discrimination and workload. Observations conducted in hospital settings and associated with a questionnaire as well as the NASA-TLX (N = 121) have shown that discriminations in a medical environment are limited. They are only related to the interpersonal aspect of care: medical acts (examination, care) are properly completed. The variations in the healthcare providers’ behavior occur when dealing with stigmatized patients and patients who are difficult to manage.
25

An Experimental Investigation of the STOL Performance of Cal Poly's AMELIA in the NFAC

Lichtwardt, Jonathan Andrew 01 April 2013 (has links)
Results from Cal Poly's recent wind tunnel test, during the Winter of 2011-2012, in the 40- by 80-foot test section at the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center are presented. AMELIA, the Advanced Model for Extreme Lift and Improved Aeroacoustics, is the first full-span, cruise efficient, short take-off and landing (CESTOL) model incorporating leading- and trailing-edge blowing wing circulation control and over-the-wing mounted turbine propulsion simulators (TPS) to date. Testing of the 10 foot span model proved successful and was the result of a 5 year NASA Fundamental Aeronautics Program Research Announcement. The test generated extensive low-speed experimental aerodynamic and acoustic measurements. All of the results associated with Cal Poly's effort will be available in an open-source validation database with the goal of advancing the state-of-the-art in prediction capabilities for modeling aircraft with next generation technologies, focusing on NASA's N+2 generation goals. The model's modular design allowed for testing of 4 major configurations. Results from all configurations are presented. Out of a total of 292 data runs, 14 repeat run configurations were obtained. Overall repeatability of test data are good. Factors contributing to non-repeatability in the test data were assessed and showed high pressure air line temperature to be a primary factor. Test data shows drastic improvements in performance are obtained when incorporating leading edge blowing: wing stall can be delayed to more than 25 degrees angle-of-attack at lift coefficients exceeding six. Without the introduction of leading edge blowing to increase boundary layer momentum and maintain flow attachment around the leading edge, STOL performance suffers. Similar runs for isolated trailing edge blowing show a reduction in maximum lift coefficient to three with stall occurring at zero angle-of-attack. Testing at two engine pylon heights allowed for the highly coupled propulsion and flow control system to be characterized.
26

DARK AGES LUNAR INTERFEROMETER (DALI): DEPLOYMENT-ROVER - CHASSIS

Stanimirovic, Tomislav, Winberg, Johan January 2013 (has links)
In this thesis we have looked at the possibility of using a rover for deployment oflunar interferometers on the far side of the Moon. This project was made togetherwith two other groups from the mechanical engineering program at HalmstadUniversity. The project was divided into three units and we had the mainresponsibility for the design of the chassis.The goal of this project is to create a better understanding of the origin of the universeand how it still to this day keeps changing. This is believed to be achievable by usinglunar interferometers that will collect data in form of cosmic microwaves from outerspace. The lunar interferometers will be placed at the far side of the Moon since thisis the only site in solar system that is shielded from human-generated interference.The work was completed in collaboration with JPL and NASA, which are worldleading designers and manufacturers of space-related products.
27

Systems integration and analysis of advanced life support technologies

Nworie, Grace A. 02 June 2009 (has links)
Extended missions to space have long been a goal of the National Aeronautics and Space Administration (NASA). Accomplishment of NASA's goal requires the development of systems and tools for sustaining human life for periods of several months to several years. This is the primary objective of NASA's Advanced Life Support (ALS) program. This work contributes directly to NASA efforts for ALS, particularly food production. The objective of this work is to develop a systematic methodology for analyzing and improving or modifying ALS technologies to increase their acceptability for implementation in long-duration space missions. By focusing primarily on the food production systems, it is an aim of this work to refine the procedure for developing and analyzing the ALS technologies. As a result of these efforts, researchers will have at their disposal, a powerful tool for establishing protocols for each technology as well as for modifying each technology to meet the standards for practical applications. To automate the developed methodology and associated calculations, a computer-aided tool has been developed. The following systematic procedures are interrelated and automatically integrated into the computer-aided tool: • Process configuration, with particular emphasis given to food production (e.g., syrup and flour from sweet potato, starch from sweet potato, breakfast cereal from sweet potato); • Modeling and analysis for mass and energy tracking and budgeting; • Mass and energy integration • Metrics evaluation (e.g., Equivalent System Mass (ESM)). Modeling and analysis is achieved by developing material- and energy-budgeting models. Various forms of mass and energy are tracked through fundamental as well as semiempirical models. Various system alternatives are synthesized and screened using ESM and other metrics. The results of mass, energy and ESM analyses collectively revealed the major consumers of time, equivalent mass, and energy, namely evaporation, condensation, dehydration, drying and extrusion. The targeted processes were subsequently targeted for modifications. In conclusion, this work provides a systematic methodology for transforming non-conventional problems into traditional engineering design problems, a significant contribution to ALS studies.
28

NASA Remote Imaging System Acquisition (RISA) Multispectral Imager Development Updates

Martin, Samuel, Mayer, Jackeline, Owan, Parker, Stephens, Kyle, Suring, Lee 10 1900 (has links)
ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The NASA Remote Imaging System Acquisition (RISA) project is a prototype camera intended to be used by future NASA astronauts. NASA has commissioned the development of this engineering camera to support new mission objectives and perform multiple functions. These objectives require the final prototype to be radiation hardened, multispectral, completely wireless in data transmission and communication, and take high quality still images. This year's team was able to successfully develop an optical system that uses a liquid lens element for focus adjustment. The electrical system uses an Overo Fire computer-on-module (COM) developed by Gumstix. The OMAP processor onboard handles all communication with a monochromatic CMOS sensor, liquid lens control circuitry, pixel data acquisition and processing, and wireless communication with a host computer.
29

An Aeroelastic Evaluation of the Flexible Thermal Protection System for an Inflatable Aerodynamic Decelerator

Goldman, Benjamin Douglas January 2015 (has links)
<p>The purpose of this dissertation is to study the aeroelastic stability of a proposed flexible thermal protection system (FTPS) for the NASA Hypersonic Inflatable Aerodynamic Decelerator (HIAD). A flat, square FTPS coupon exhibits violent oscillations during experimental aerothermal testing in NASA's 8 Foot High Temperature Tunnel, leading to catastrophic failure. The behavior of the structural response suggested that aeroelastic flutter may be the primary instability mechanism, prompting further experimental investigation and theoretical model development. Using Von Karman's plate theory for the panel-like structure and piston theory aerodynamics, a set of aeroelastic models were developed and limit cycle oscillations (LCOs) were calculated at the tunnel flow conditions. Similarities in frequency content of the theoretical and experimental responses indicated that the observed FTPS oscillations were likely aeroelastic in nature, specifically LCO/flutter. </p><p>While the coupon models can be used for comparison with tunnel tests, they cannot predict accurately the aeroelastic behavior of the FTPS in atmospheric flight. This is because the geometry of the flight vehicle is no longer a flat plate, but rather (approximately) a conical shell. In the second phase of this work, linearized Donnell conical shell theory and piston theory aerodynamics are used to calculate natural modes of vibration and flutter dynamic pressures for various structural models composed of one or more conical shells resting on several circumferential elastic supports. When the flight vehicle is approximated as a single conical shell without elastic supports, asymmetric flutter in many circumferential waves is observed. When the elastic supports are included, the shell flutters symmetrically in zero circumferential waves. Structural damping is found to be important in this case, as "hump-mode" flutter is possible. Aeroelastic models that consider the individual FTPS layers as separate shells exhibit asymmetric flutter at high dynamic pressures relative to the single shell models. Parameter studies also examine the effects of tension, shear modulus reduction, and elastic support stiffness.</p><p>Limitations of a linear structural model and piston theory aerodynamics prompted a more elaborate evaluation of the flight configuration. Using nonlinear Donnell conical shell theory for the FTPS structure, the pressure buckling and aeroelastic limit cycle oscillations were studied for a single elastically-supported conical shell. While piston theory was used initially, a time-dependent correction factor was derived using transform methods and potential flow theory to calculate more accurately the low Mach number supersonic flow. Three conical shell geometries were considered: a 3-meter diameter 70 degree shell, a 3.7-meter 70 degree shell, and a 6-meter diameter 70 degree shell. The 6-meter configuration was loaded statically and the results were compared with an experimental load test of a 6-meter HIAD vehicle. Though agreement between theoretical and experimental strains was poor, circumferential wrinkling phenomena observed during the experiments was captured by the theory and axial deformations were qualitatively similar in shape. With piston theory aerodynamics, the nonlinear flutter dynamic pressures of the 3-meter configuration were in agreement with the values calculated using linear theory, and the limit cycle amplitudes were generally on the order of the shell thickness. Pre-buckling pressure loads and the aerodynamic pressure correction factor were studied for all geometries, and these effects resulted in significantly lower flutter boundaries compared with piston theory alone. </p><p>In the final phase of this work, the existing linear and nonlinear FTPS shell models were coupled with NASA's FUN3D Reynolds Averaged Navier Stokes CFD code, allowing for the most physically realistic flight predictions. For the linear shell structural model, the elastically-supported shell natural modes were mapped to a CFD grid of a 6-meter HIAD vehicle, and a linear structural dynamics solver internal to the CFD code was used to compute the aeroelastic response. Aerodynamic parameters for a proposed HIAD re-entry trajectory were obtained, and aeroelastic solutions were calculated at three points in the trajectory: Mach 1, Mach 2, and Mach 11 (peak dynamic pressure). No flutter was found at any of these conditions using the linear method, though oscillations (of uncertain origin) on the order of the shell thickness may be possible in the transonic regime. For the nonlinear shell structural model, a set of assumed sinusoidal modes were mapped to the CFD grid, and the linear structural dynamics equations were replaced by a nonlinear ODE solver for the conical shell equations. Successful calculation and restart of the nonlinear dynamic aeroelastic solutions was demonstrated. Preliminary results indicated that dynamic instabilities may be possible at Mach 1 and 2, with a completely stable solution at Mach 11, though further study is needed. A major benefit of this implementation is that the coefficients and mode shapes for the nonlinear conical shell may be replaced with those of other types of structures, greatly expanding the aeroelastic capabilities of FUN3D.</p> / Dissertation
30

Dark Ages Lunar Interferometer - Deployment Rover : Propulsion and Steering Systems / Dark Ages Lunar Interferometer - Utplaceringsrover : Framdrivning- och styrsystem

Birgersson, Victoria, Lundgren-Goodman, Maximillian January 1900 (has links)
2030 NASA Jet Propulsion Laboratory will place an interferometer, which will workas a radio telescope, on the far side of the Moon. The interferometer uses thinpolyamide films as antennas, which are rolled out by a rover (an autonomousvehicle). The thesis covers concept generation of the propulsion and steering systemof the rover.The interferometer is to be placed on the far side of the Moon in order to ensure, asfar as possible, that it is not effected by radiation from Earth. The interferometerconsists of several polyamide films, approximately 100 meters long and one meterwide. The films are to be connected in the middle in order to form a star pattern offilm. Since the rover is to roll out these films on the surface of the Moon, it will driveback and forth to the lander to pick up the rolls. The focus in the project has been todevelop a reliable and stable system as possible so that the rover can accomplish itsmission without malfunctions. The purpose with the interferometer is to map thehydrogen gas clouds which were formed during universe’s youth (Platt, 2008).The outcome of this project is a concept indicating what the most optimal design ofwheel mount, of motor mount, of wheel and steering design may be in order to steerthe rover. The method to generate concepts used is known Fredy Olsson’s method.This is a method that has been developed at Lunds University and it has been widelyused in engineering education at Halmstad University.The four concepts developed and contributes to the whole concept for propulsion andsteering system of the rover. The four concepts developed are an all six steering, allof the six wheels can be controlled individually. Each wheel is split, or divided intwo. The motor is angle mounted and the wheel is semi-open with a slope that makesthe Moon dust fall out if it comes inside.Inspiration from previous rovers which are or have been on the Moon and Mars hasbeen useful in generating concepts. Previously used concepts are stable and reliable,which are important factors in this project. Previous theses have come to theconclusion that the chassis of the rover should be the one similar to the one used onMars Science Laboratory Curiosity and Mars Exploration Rover’s Spirit andOpportunity.The Halmstad University projects in collaboration with NASA began at HalmstadUniversity in 2013, and previous projects have developed the chassis, energy systemand the deployment mechanism of the rover. This year’s project takes intoconsideration the results from previous years since a concept of a complete roverultimately is going to be presented to NASA Jet Propulsion Laboratory.The thesis is done in collaboration with NASA Jet Propulsion Laboratory inCalifornia, USA. NASA Jet Propulsion Laboratory is the leading U.S. center forrobotic exploration of the solar system. / NASA Jet Propulsion Laboratory ska 2030 placera en interferometer på månensbaksida, interferometern ska fungera som ett radioteleskop. Interferometern användersig av tunna polyamidfilmer som antenner. Dessa ska rullas ut på månens yta av enrover (ett obemannat fordon). Rapporten behandlar framtagning av koncept förstyrning och framdrivning av denna rover.Interferometern ska placeras på månens baksida för att man i så stor mån som möjligtvill undkomma strålningsstörningar från Jorden. Interferometern ska bestå av flertaletpolyamidfilmer, ca 100 meter långa och en meter breda. Filmerna skasammankopplas i en kontrollenhet som finns i mitten av det stjärnformade mönsterfilmerna läggs i. Då rovern ska placera ut dessa filmer på månens yta, ska den skaköra från och till landaren för att hämta upp rullarna. Fokus i projektet har varit attgöra ett så pålitligt stabilt system som möjligt för att rovern ska klara av att slutförasitt uppdrag utan driftstörningar. Med interferometern vill man sedan kartläggavätgasmoln som bildades i universums ungdom (Platt, 2008).Resultatet av projektet är ett koncept som visar roverns framdrivnings- ochstyrsystem, hjulupphängning, motorplacering samt hur hjuldesignen kan se ut. FredyOlssons metoder har använts för att ta fram koncept som uppfyller krav och önskemåldå denna metod har använts tidigare under utbildningen.De fyra koncept som bidrar till ett koncept för hela styr- och framdrivningssystem ärstyrning och framdrivning på roverns alla sex hjul, hjulen är designade på så vis att deär delade i två. Motorn är vinkelmonterad. Roverns hjul är semi-öppna med en kantsom är högre än det djup hjulet sjunker ner i månytan., med en sluttning inuti för attsand och damm ska rinna ut.Inspiration har kommit från tidigare rovrar som varit/är aktiva på månen och Mars dådet är beprövade koncept som visat sig vara stabila och pålitliga. Tidigareexamensarbeten har kommit fram till att det chassi som ska användas är snarlikt detsom använts på Mars Science Laboratory Curiosity och Mars Exploration Rover’sSpirit och Opportunity.Projektet började på Högskolan i Halmstad 2013 och tidigare projekt har tittat påbland annat chassit, energisystem och utplaceringsenheten. Årets projekt har tagithänsyn till resultat från tidigare år, för att ett koncept på en hel rover slutligen skakunna visas upp för NASA Jet Propulsion Laboratory.Examensarbetet är genomfört i samarbete med NASA:s Jet Propulsion Laboratory iKalifornien, USA, vilka är USA:s center för robotisk utforskning av solsystemet.

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