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End date: 2013 × Start date: 2011 × search.filters.applied.f.resourcesubtype: Masters Project ×

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Now showing 1 - 10 of 168
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Investigation of Drag Modulated Supersonic Inflatable Aerodynamic Decelerators for Use on Sounding Rocket Payloads

2013-12-13 , Miller, Matthew J.

This paper presents an assessment of use of a supersonic inflatable aerodynamic decelerator for drag modulation of a sounding rocket payload bus structure as part of a high-altitude sample return mission. The scientific goal of this mission is to capture mesospheric dust and particulate matter located 45 km to 85 km in altitude. This mission is also to demonstrate technology that is capable of precise landings by combining a decelerator system comprised of inflatable aerodynamic decelerator to reach within 10 km with a guided parafoil system. Three decelerator configurations, the tension cone, attached isotensoid, and the trailing isotensoid, were examined on the metrics of decelerator mass, aerodynamic performance, and vehicle integration. The attached isotensoid was found to be the most mass efficient option, while the trailing isotensoid was determined to be preferable from an overall system level perspective. The decelerators’ precision landing capability through the use of drag modulation was also evaluated. Downrange error was reduced by 21% by drag modulation as compared to an 8.5 m supersonic disk-gap-band parachute. When coupled with a guided parafoil, drag modulation provides a 95% confidence level in landing within the 10 km parafoil capability region, and a 76% confidence level of landing within 5 km of the target.

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Strategic Planning for Kaohsiung's Free Economic Zone (FEZ) and New Asian Bay Area: A Report of Waterfront Revitalization Studio 2013

2013-12 , Aguilar, Johnny , Cadet, Sherene , Riley, Dawn , Manley, Canon , Keffer, Rebecca , Xie, LiWei , Sinharoy, Sinan , Braswell, Daniel , Pessoa, Lauren , Quan, Jige

The City of Kaohsiung has great deal of economic development and public policy potential that is addressed by the Policy Group. Most of the work in this section centers around the concept of the Kaohsiung Free Economic Demonstration Zone, which is currently being planned by both the city government and the central government of Taiwan. The policy group learned about some of the main goals and visions of the Free Economic Zones (FEZ) after meeting with local officials from the Bureaus of Urban Development and Economic Development. The primary goals outlined in a presentation about the future of FEZs in Taiwan include creating employment, attracting investment, and enhancing industrial competitiveness and efficiency. The government intends to achieve these goals by joining free trade agreements and promoting economic liberalization through a relaxation of business and trade regulations.

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Aerodynamic Stability and Performance of Next-Generation Parachutes for Mars Descent

2013-07-18 , Gonyea, Keir

The aerodynamic stability and performance characteristics of next-generation supersonic parachutes were determined through wind tunnel testing. Canopy configurations included the disk-gap-band (DGB), ringsail, and ringsail-variant designs referred to as the disksail and starsail. Stereo photogrammetric processing was performed during testing, which was then used to estimate the static and dynamic moment coefficient curves as a function of total angle of attack. The dynamic components of the angle of attack and sideslip angle were shown to be significant, heavily influencing the resulting total angle of attack profile and moment coefficients. Uncertainty in the apparent mass of the canopies resulted in uncertainty in the moment coefficient magnitudes. From the stability curves, the peak moment, trim total angle of attack, and pitch stiffness at the trim angle could be determined. Parachute stability was assessed in the context of drag load and geometric porosity. An inverse relationship between the drag load and the stability of the canopies was generally seen. The DGB canopies tended to be more stable while the ringsail and disksail canopies had more drag. Similar stability properties as the DGB with slightly higher drag loads were obtained by increasing the geometric porosity distribution around the crown of the disksail canopies.

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Urban Design and Georgia's Medium-Sized Towns: Issues and Prospects

2013-05 , Hampton, Travis N.

There are sixteen medium-sized rural towns in Georgia that are located outside a census-designated metropolitan area. The populations of these towns vary between 10,000 and 50,000 people with the majority located in the southern regions of the state. These towns have historically been consid ered the sub-regional nexuses for agriculture, transportation, and commerce that connect directly to the Georgia’s larger cities and regions. However, in recent decades along with other smaller-sized towns, some areas are experiencing job losses, outward migrations of younger people to larger cities, a lack of funding resources for new projects, and poverty rates which are often considerably higher than more urban/suburban areas. At the same time, these areas have also grown in sprawled patterns similar to larger metropolitan suburbs. This paper investigates this sprawled growth and focuses on whether any urban design methods or regulations have influenced the current development of these towns. This research is guided by three establishing questions. The first being, what constitutes the current urban morphology of these towns? Secondly, what are the aspirations and visions set forth by each of these towns? Thirdly, how has each town’s urban form been shaped over time through their primary regulatory documents to reflect or not reflect their aspirations and visions? The first question will be answered by employing a method of analysis similar to the urban morphology framework set out in Brenda Case Scheer’s essay “Anatomy of Sprawl.” This includes the mapping of static, elastic and campus tissues as well as resilient tissues with Google Earth and ESRI ArcGIS being the primary resources. The second question will be answered by a summary analysis and comparison of each town’s comprehensive planning documents available from the Georgia Department of Community Affairs and other agencies. The third question will be answered by examining the primary regulatory documents of these towns (e.g. zoning ordinances, subdivision regulations, etc.) to determine how the urban form has been shaped over time legally. This will involve examining the codes of ordinances via Municode () or from an additional government resource and comparing the analysis. By comparing and contrasting each town’s existing urban form conditions, their comprehensive plans, and their regulatory frameworks, planners and urban designers can gain a better understanding as to what a medium-sized town’s strengths and weaknesses are from an urban design and planning standpoint. This can then suggest what the next steps are in reforming regulations and methods that will in turn influence development patterns for future growth and cultural vitality.

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Supersonic Propulsive Divert Maneuvers for Future Robotic and Human Mars Missions

2013-12-13 , Mandalia, Amit B.

Future robotic and human missions to Mars require improved landed precision and increased payload mass. Two architectures that seek to meet these requirements using supersonic propulsive diverts are proposed in this paper: one utilizing a high-altitude propulsive divert and another with thrust vectoring during supersonic retropropulsion. Low ballistic coefficient entry vehicles decelerate high in the thin Mars atmosphere and may be used to deliver higher-mass payloads to the surface. A high-altitude supersonic propulsive divert maneuver is proposed as a means of precision landing for low ballistic coefficient entry vehicles that decelerate to supersonic speeds at altitudes of 20-60 km. This divert maneuver compares favorably to traditional precision landing architectures with up to 100% improvement in range capability while saving over 30% in propellant mass. Architectures which utilize hypersonic vehicles with ballistic coefficients of 10 kg/m2 were found to land within 500 m of a target with this maneuver alone. This high-altitude divert range capability is sensitive to altitude and flight-path angle variations at maneuver initiation and relatively insensitive to velocity at initiation. Propellant mass fraction is relatively invariant to the initial conditions and correlates directly with the divert distance. Supersonic retropropulsion has also been proposed as a means to deliver higher-mass payloads to the surface, and thrust vectoring during supersonic retropropulsion can save a substantial amount of fuel in a precision landing scenario. Propellant mass savings greater than 30% are possible if thrust vectoring is unconstrained during the supersonic phase of flight. Propellant mass fraction is found to be sensitive to the divert direction and also the altitude and flight-path angle, favoring low altitudes and shallow flight-path angles.

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A Case Study on Street Design

2013-12 , Fambro, Sonya

This paper will look at several contemporary theories of street design in order to get a better understanding of how streets in Atlanta could be redesigned and repur¬posed with the understanding of streets as being “sym¬bolic, ceremonial, social, and political places [Jacobs 5].” I will begin first by analyzing the history of the street as it was established throughout ancient Rome, 15th century Renaissance, the Medieval era, Baroque, New York in the 1900s, and modern day suburbia in order to give context to the theoretical ideas that are currently being applied. Then I will look at some of the issues in the design of streets, in order to understand why streets are so difficult to design. Finally, I will analyze each theory through the use of case studies in order to understand how they dealt with and overcame the issues of street design and how these theories might be applicable to Atlanta.

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Photogrammetry Analysis of a Hypersonic Inflatable Aerodynamic Decelerator Structural Test Article

2013-07-11 , Li, Lin

Analysis was performed on photogrammetry data of a 6m Hypersonic Inflatable Aerodynamic Decelerator (HIAD), an inflatable stacked torus used to aid in atmospheric entry, to understand its structural dynamics. Photogrammetry data was obtained during wind tunnel testing under various loading conditions. Test parameters included the freestream dynamic pressure, yaw angle and internal inflation pressure. In addition, two HIAD configurations were analyzed, the basic stacked torus (Baseline configuration) and a second configuration adding a torus near the shoulder to aid in rigidity (Tri-Tori configuration). The analysis includes estimating the deflection of the HIAD under loading as well as calculating the standard deviation relative to the mean deflection and the frequency content of the dynamic response. Under load, the deflection angle for each configuration ranged from 1° to 3° (1σ). Analysis of the results indicates that the Tri-Tori configuration did not demonstrate significant benefit over the Baseline. The photogrammetry data showed that the oscillatory motion increased with higher dynamic pressure but was insensitive to yaw angle. In addition, the analysis showed that the standard deviation of the HIAD shape with respect to the average deflection increased while moving radially outwards. However, the standard deviation values calculated from different camera pairs were inconsistent and did not produce the same standard deviations especially at the interface region. The frequency analysis showed that each radial member behaved similarly to a rigid oscillator, having the same frequency content of motion along each radial direction and increased amplitude when moving radially outward. Both the frequency and shape standard deviation analyses showed that the motion of the HIAD was piecewise continuous in the azimuthal direction. These discontinuities likely arose when stitching together the images from different camera pairs. The photogrammetry data is a valuable dataset providing insight into the static and dynamic response of the HIAD under loading. However, inconsistencies in the camera imaging and stitching need to be resolved and higher temporal resolution will improve the fidelity of analysis

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Flexible Thermal Protection System Physics-Based Modeling for Temperature Profile Predictions

2013-12-03 , Rossman, Grant A.

Candidate material testing was performed on various Flexible Thermal Protection Systems (FTPS) layup configurations in an arc-jet ground test facility. A physics-based thermal model was created to predict the thermal-material response of each FTPS layup under arc-jet induced thermal loading. Initial thermal model temperature predictions of embedded thermocouples for FTPS test articles showed an unsatisfactory correlation to arc jet test data. The Levenberg-Marquardt (LM) inverse parameter estimation technique was implemented to reduce discrepancies between thermal model temperature predictions and experimental thermocouple temperature measurements by iteratively modifying FTPS thermal parameters within the model, such as thermal conductivity and specific heat. A formal parameter estimation methodology, previously applied for ablative TPS, is applied to this FTPS problem to improve understanding estimation behavior and LM error minimization. Nominal, uncertainty, sensitivity, and inverse analysis are performed on scaled thermal inputs to provide insight on solution uniqueness and stability. This error minimization technique is demonstrated on a previously flown FTPS layup configuration consisting of two outer fabric layers, two insulation layers, and one gas barrier layer. Results show that the LM method is a viable technique for inverse parameter estimation of FTPS thermal modeling problems.

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The Economic Impact of Sea Level Rise on Port of Savannah's Garden City Terminal & City of Darien

2013-12 , Coburn, Carolyn , Cornwell, Andrew , Glostner, Joshua , Hylton, Peter , Risher, John , Skinner, Jill , Wilson, Richard

The Garden City Terminal at the Port of Savannah is one of the largest and fastest growing container ports in the country, making it an economic engine locally and nationally. The Terminal is an integral economic component on several scales: locally, it supports many households in and around Chatham County; regionally, the port supports wider distribution networks and regional agriculture and manufacturing; and nationally, the port serves as a gateway to access markets across the globe. Therefore rising sea levels projected over the next 100 years make port disruptions an important economic threat on a variety of scales. This report describes the economic threat that sea level rise poses to port and port-related operations through permanent inundation, worsening storm surge, and other environmental changes at local, regional and statewide scales. The team drew on research by Keating and Habeeb (2012) and created new tools for assessing the potential impacts on jobs, property, transportation links, and other businesses. The intent is to provide actionable projections for business leaders, policy makers, and individuals in areas that may eventually have to respond to the effects of sea level rise.

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A Method to Characterize Parachute System Instability Modes

2013-06-05 , Bernatovich, Michael , Clark, Ian

A simplified, yet robust, parachute system stability analysis is performed using a 5-DOF (altitude, pitch, & yaw) descent trajectory simulation. Several trade studies are performed to determine what types of initial conditions and wind perturbations can result in pitching (i.e. planar) or coning instability modes. Building on these results, several vehicle design sensitivities are performed to roughly describe the trend in stability with canopy trailing distance, canopy diameter, & payload mass. As a complement to these sensitivities and trade studies, an early Mars EDL research drop test is analyzed as a case study. During this drop test, the system experienced uncharacteristically large pitch oscillations primarily driven by canopy vortex shedding. Data from this drop test will be used to determine the trajectory & vehicle design space within which this behavior could be expected.

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