Virginia Space Grant Consortium
2012 Student Research Conference
April 5, 2012

Luncheon Sponsored by the College of William and Mary at the Williamsburg Hospitality House, Williamsburg, Virginia

Graduate Research Scholars

Oral Presentations
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Oral Presentations – Empire Room A
Applied Science


CHARACTERIZATION AND MANAGEMENT OF STRESS
CORROSION CRACKING IN ULTRA HIGH STRENGTH STEELS

Greger Pioszak, University of Virginia
The objective of this work is to test the hypothesized beneficial effect of cryogenic processing on
stress corrosion cracking (SCC) of a modern ultra-high strength steel, Aermet® 100. The
mechanistic justification is elimination of thin-film austenite at martensite lath interfaces. Thin
film austenite becomes hydrogen saturated due to environmental exposure during service; and
transforms to embrittled martensite under crack tip strain. Experiments yielded two dramatically
different classes of SCC behavior for fatigue precracked single edge notch (SEN) specimens
stressed in 3.5% NaCl solution near the free corrosion potential. One-half of eight replicate
experiments with the LN2 chilled condition evidenced immunity to SCC, while four experiments
yielded significant transgranular SCC identical to that observed for commercially processed
Aermet® 100 UHSS. While the deleterious role of residual austenite is logical and justified
theoretically, there is no direct evidence for LN2-dependent change in the typically low amounts
of this austenite. An explanation for the bimodal SCC response based on heterogeneous CrS
dissolution is supported by measured-high Cr enrichment in the corrosion product present only
on fast SCC surfaces; however, CrS is not evidenced in the microstructure. The technological
impact of near-immune SCC response for ultra-high strength steel justifies continued research on
the role of residual austenite.


ASYNCHRONOUS REAL-TIME CONTROL OF A ROBOTIC ARM
USING A BRAIN-COMPUTER INTERFACE

Garett Johnson, Old Dominion University
A Brain-Computer Interface (BCI) allows for individuals to send commands and messages using
an atypical form of communication: brain activity. Currently these devices are used by disabled
individuals with afflictions of the motor-neuron system, e.g., amyotrophic lateral sclerosis.
Ultimately such systems could prove beneficial to everyone by providing an additional channel
of communication and control, and research is currently underway concerning non-medical uses
of BCI technologies. One potential benefit of an additional control channel for healthy humans
would apply to astronauts, who routinely experience ‘space sickness’ and disorientation during
their first few days in a weightless environment. An output channel from the human body that is
not dependent on typical motor control, which may be inhibited due to space sickness, is one
possible solution to this problem. Here we present a case study involving the use of an EEG
based BCI that uses steady-state visual evoked potentials on a healthy individual to
asynchronously control a 6-degree of freedom robotic arm through custom software in real-time
with high accuracy.

DEVELOPMENT OF A COHESIVE REACTIVE BOUNDARY LAYER
MODEL FOR ABLATING SURFACE APPLICATIONS

Ryan Johnson, University of Virginia
This investigation focuses on the development of a reactive boundary layer model for ablating
surfaces. This model is of interest to NASA initiatives due to its applicability to the reacting
boundary layers present on the exterior of re-entry vehicles. This research is currently done in
coordination with experimentalists at the Air Force Institute of Technology (AFIT), where the
simulations will be applied to the reactive boundary layer present on missile surfaces caused by
laser induced ablation. This paper will show that progress has been made since the accepted
proposal as well as outline necessary future work. Results for low-speed regime reacting surfaces
are obtained through a finite-volume, open-source, Computational Fluid Dynamics package,
OpenFOAM. The code was modified to contain detailed transport, thermodynamics and surface
reactions for porous carbon. Results show that, with the use of the detailed gaseous reaction
mechanism, the flow residence time is an important parameter in understanding the mixing
layers and species presence over reacting flat plates. This research was made possible by the
Virginia Space Grant Consortium Graduate Fellowship.


THE POPULATION DYNAMICS OF THE BACTERIAL COMMUNITY
DURING DOLIOLETTA GEGENBAURI DECOMPOSITION

Maryse Leandre, Virginia Tech
Consideration of the trophic interactions that link species requires study of the decomposition
process to reveal different pathways for nutrient regeneration, elemental recycling, and microbial
production in the water column. In this study, the presence and activity of
Gammaproteobacteria, Alphaproteobacteria and Sphingo-Flavobacteria were assessed during
decomposition of the filter-feeding tunicate, Dolioletta gegenbauri. Bacterial abundance and
community composition were analyzed using epifluorescence microscopy with 4’, 6-diamidino-
2phenylindole (DAPI) staining and fluorescent in-situ hybridization (FISH). DAPI results
presented cell counts that fell within the normal range of 105
to 107 cells mL-1for oligotrophic
and mesotrophic aquatic environments. Examining the FISH data revealed a high abundance of
the SAR11 cluster, a α−Proteobacterium, at the initiation of the study representing 36% probe
cell counts. The Gammaproteobacteria exhibited dominance at time points 38 and 68 hours,
15% and 26%, while the Sphingo-Flavobacteria dominated the conclusion of the experiment
with 36.7%. Bacterial clones were sequenced and evaluated further for identification using the
Ribosomal Database Project (RDP). The Alphaproteobacteria were the predominant bacterial
group signifying 41.7% of the nucleotide sequences at time 0 of the study. Similar to the FISH
results, at 38 hour the Gammaproteobacteria dominated the sequences representing 64.5%. At
time point 68 hour, once again the Alphaproteobacteria, 27.3%, were the most abundant bacteria
in the sample. The Sphingo-Flavobacteria displayed a high abundance towards the conclusion of
the study with 41.9%. Conclusions can be inferred that the bacteria in these mesocosms
demonstrate similar interactions and activities as oceanic bacteria. Environmental constraints
and energetic requirements combine to determine the successive dominance of the different
bacteria. The data provided can contribute insights into the nutrient pathways between filterfeeding
zooplankton and microbial communities following tunicate and plankton blooms.


SEARCHING, SELECTING AND SYNTHESIZING SOURCE CODE
COMPONENTS

Colin McMillan, College of William & Mary
Although popular text search engines allow users to retrieve similar web pages, source code
search engines do not have this feature. Knowing similarity between applications plays an
important role in improving understanding and assessing reusability of these applications, rapid
prototyping, and discovering code theft and plagiarism. However, detecting similar applications
is a notoriously difficult problem, since it implies that similar high-level requirements and their
low-level implementations can be detected and matched automatically for different applications.
We present our approach for automatically detecting Closely reLated ApplicatioNs (CLAN) for a
given Java application. CLAN compares applications based on the calls they make to the
standard Java Application Programming Interface (API). Our idea is that similar applications
will make similar API calls. CLAN is publicly available via a standard web browser; users may
view similar applications as well as the API calls they share.


THE URBAN HEAT ISLAND DURING EXTREME HEAT EVENTS:
ASSESSING VARIABILITY TO UNDERSTAND HUMAN HEALTH
IMPACTS

David Hondula, University of Virginia
Extreme heat events are associated with a significant health burden. In the United States,
extreme heat ranks as the leading weather-related cause of death, and a larger number of
hospitalizations and illnesses are also attributable to high temperature events. We have found that
the heat-related mortality rate within metropolitan areas is not uniform; some localities are
associated with mortality rates statistically significantly above the citywide average when an
extreme heat event occurs. Within metropolitan areas the varying thermal and radiative
properties of the built environment create zones where air and surface temperatures are markedly
higher than the surrounding suburbs and countrywide—the “urban heat island.” We are
investigating the relationship between the urban heat island and mortality to determine if higher
temperatures in certain areas are contributing to the health burden associated with extreme heat.
Our examination of the urban heat island is based on LANDSAT imagery. We have developed a
collection of twenty-one maps of the surface urban heat island during extreme heat events for
Philadelphia, PA, and found systematic variability that encourages the use of a large set of
images in future studies examining the local scale heat-health response.

DESIGN, DEVELOPMENT, AND TESTING OF A SCOOP SAMPLE
COLLECTION SYSTEM

Matthew Torok, Virginia Tech
Sample collection, whether for in situ analysis or retrieval and return, is a critical component of
many interplanetary exploration missions. Therefore, it is important to create a reliable,
straightforward mechanism for gathering and containing samples from a planet’s surface. Here a
novel means of collection, namely a scooping device, is created to achieve this goal. The scoop
sample collection system is paired with a small ground robot at the Virginia Tech Unmanned
Systems Laboratory to provide a platform for power and mobility. This paper describes the
design, development, fabrication, and testing of the complete collection system. A dual scoop
design is presented to meet all weight and size constraints, as well as both collecting and
containing a sample utilizing the same hardware components.


USING LOW GRAVITY CARDIOVASCULAR EFFECTS TO RELATE
MYOCARDIAL REMODELING TO THE FILLING DYNAMICS OF THE
LEFT VENTRICLE

Casandra Niebel, Virginia Tech
This work aims to further current understanding of the physics behind left ventricular (LV)
filling by analyzing how the diastolic filling wave changes in various LV geometries. The LV is
known to remodel in disease and as part of the natural aging process. Astronauts also see a
change in LV geometry when exposed to micro gravity as their physiological systems quickly
adapt to this new environment. Even after short term missions, astronauts may experience
weakened circulatory systems after returning to earth, including an atrophied LV, with decreased
mass and volume. The relationship between LV filling wave dynamics and LV geometries is
investigated. A temporally varying physical wave propagation velocity is measured using a
continuous wavelet transform analysis on Color M-Mode echocardiogram data and applied to a
patient cohort with various LV geometries. The presented analysis is contained in an automated
algorithm which outputs common clinical parameters from clinical scans which would be useful
on long duration space missions when there is no physician on board. Also, this improved
insight into the effect of changes in LV geometry on the heart filling wave will improve
understanding of heart disease, leading to improved diagnostics and treatment procedures here
on earth.


HIGH PERFORMANCE COMPOSITE STRUCTURES THROUGH
MATERIAL TAILORING

Paul Zheng, Virginia Tech
This paper introduces and expands on the idea of material tailoring carbon fiber composite shells
to address NASA’s mission of improvements in aircraft performance, specifically the structural
performance of “next generation” aircrafts. Currently, new aircraft designs are being
implemented to improve the aerodynamics and fuel efficiency of these modern day marvels, but
the structural capacity of these structures has not improved in such a rate to accommodate these
innovations. The “next generation” aircrafts utilize non-circular cross-sections as the fuselage
and wing shapes. Unfortunately, non-circular cross-sections exhibit a decrease in structural
performance when compared to traditional cylindrical shells. The research goal was to
implement various fiber angle orientations to elliptical composite shells through finite element
analysis to determine the structural performance and note any improvements on compression and
bending load cases. The elliptical composite cylinders with varying fiber orientations were
compared to a quasi-isotropic elliptical shell and an equivalent quasi-isotropic circular composite
shell. Also, the feasibility of manufacturing continuously varying fiber orientation composite
shells is discussed.


ANALYSIS AND CONTROL OF NONLINEAR FLOW-STRUCTURE
INTERACTIONS

Justin Webster, University of Virginia
We consider an aeroelastic model known as a nonlinear flow-structure interaction, which
describes the oscillations of a thin, flexible plate immersed in a potential flow. This model is
used to study the phenomenon known as flutter, which involves the coupling of the plate's
vibrational modes with the aerodynamic load. Here, we treat this problem from a partial
differential equations point of view and state results on well-posedness and long-time behavior
of the system. The flow is described by a wave equation perturbed by a term which is
proportional to the flow velocity. The plate is modeled by Kirchoff's equation; various boundary
conditions and the physical (Berger and von Karman) nonlinearities are considered for the plate.
Strong coupling between the two equations occurs in the acceleration potential (plate forcing
term) and the down-wash (Neumann type boundary condition on the flow). The key parameters
in this analysis correspond to the laminar flow velocity and the thickness of the plate.


EXECUTION TRACE ANALYSIS FOR THE SOFTWARE
DEVELOPMENT OF SAFETY CRITICAL SYSTEMS

Judith Providence, College of William & Mary
High quality software is an important part of mission critical systems. In order to attain high
quality software and detect potential errors, the software must go through a rigorous testing
process. Our goal is to automatically relate test failures based on the similarity of their
execution traces. Our research involves determining the similarity of execution traces based on
appropriate measures. More specifically, our research focuses on if more information results in
a better identification of duplicate error reports. We compared three different approaches which
were based on the cosine similarity formula. Each approach progressively contained more
information about the execution traces. The approaches involved a binary-based, integer-based
and a grammar-based version of the cosine similarity formula. Based on empirical evidence,
we conclude that the binary-based approach out-performed the integer-based and grammar-based
approach in determining the similarity of execution traces.

USING OCCUPANCY PATTERNS TO INFER LANDSCAPE
CONNECTIVITY FOR BREEDING ANURANS

Dan Ramos, College of William & Mary
Landscape connectivity is critical to maintaining viable populations within patches of suitable
habitat and is a function of the surrounding matrix’s resistance to an organism’s movement. As
land use within the matrix varies, it can be expected that landscape connectivity will vary and as
connectivity decreases, the probability of habitat occupancy by a species will decrease as well.
Recognizing the difficulty in directly measuring landscape connectivity, my study attempts to
model the relationship of Anuran, frog and toad, distributions to anthropogenic land use in the
landscape matrix as a proxy for measuring connectivity. I use calling survey data of breeding
Anurans to model occupancy probabilities in potential breeding ponds in eastern Virginia.
Occupancy modeling is a likelihood-based method to estimate occupancy probabilities when the
probability of detecting a species is less than one. Anthropogenic land use in the matrix around
breeding sites is calculated in a Geographic Information System using a land cover map. The
output of this analysis will ultimately be used to develop a spatially explicit landscape
connectivity model for Anuran species in eastern Virginia. This connectivity model will enable
land managers to evaluate impacts of proposed land uses on landscape connectivity and Anuran
population viability.

EFFECTS OF MOTION ON NEUROCOGNITIVE PERFORMANCE:
IMPLICATIONS FOR COMMERCIAL SPACE

Brittany Neilson, Old Dominion University
Human performance research in space focuses on two primary areas of study: 1) understanding
the effects of microgravity on human functioning and information processing and 2) monitoring
neurocognitive performance while exposed to the microgravity environment of space. However,
a largely unrecognized condition observed during space flight and other common forms of
transportation may also impact human performance: sopite syndrome. Sopite syndrome is
characterized by a unique set of symptoms, including drowsiness despite receiving an adequate
night’s rest, fatigue, mood changes, and apathy, and is thought to be a neurovestibular response
to motion. Identifying sopite syndrome as a contributor to symptoms experienced during space
flight is imperative to job performance, public safety, and individual health. The purpose of this
study is to understand the effects of sopite syndrome on cognitive performance, workload,
autonomic and cortical arousal, and self-reported emotional and physical symptoms. A further
goal is to use the results of this research to develop a quantitative method for converging
physiological, behavioral, and subjective/emotional indicators to assess and monitor soporific
effects on humans in space.

BLOOD FLOW CHARACTERIZATION IN A PERFUSED COLLAGEN
VESSEL BIOREACTOR USING X-RAY MICRO-PIV

Elizabeth Voigt, Virginia Tech
The design of well-characterized, adaptable, blood-perfused tissue models has become a central
objective of the emerging field of tumor engineering, as physiologically accurate in vitro
vascular models can provide new avenues for modulation of the tumor microenvironment and
preclinical evaluation of the therapeutic potential of new treatments. The characterization of fluid
parameters in perfused tissue models is a critical step towards understanding and manipulation of
the tumor microenvironment. The recent development of x-ray phase contrast particle image
velocimetry has enabled measurement of blood flow in simple systems. This study presents highresolution
blood velocity measurements in a three-dimensional collagen microvessel bioreactor
using synchrotron x-ray illumination. These results provide the groundwork for future flow
measurements in a fully functioning blood-perfused tumor model.


Oral Presentations – Yorktown Parlor Room 2
Applied Physics


THE SEARCH FOR DECAYING DARK MATTER

Gardner Marshall, College of William & Mary
Dark matter is believed to comprise approximately eighty-three percent of the matter in the
universe, yet little is known about how it fits into our picture of the elementary particles that
make up the world around us. There are now many great efforts underway to try and detect dark
matter and probe the nature of its relation to the Standard Model of particle physics. In this work
we investigate the possibility of leptonically decaying dark matter using terrestrial neutrino
telescopes. We apply the results to models of spin-1/2, charge-asymmetric dark matter whose
parameters have been fitted to describe the observed electron-positron flux seen at the PAMELA,
H.E.S.S., and Fermi-LAT experiments.


CASE STUDY OF A HYBRID LES/RAS APPROACH USING TURBULENCE
RECYCLING

Jesse Quinlan, University of Virginia
As hybrid large-eddy/Reynolds-averaged simulations become the preferred tool for simulating
high-speed unsteady flows, validation of the approach and its extensions will become
increasingly important. As part of this necessary validation campaign, simulations of a
supersonic recessed-cavity flow are performed using a hybrid large-eddy/Reynolds-averaged
simulation approach in conjunction with a turbulence recycling procedure. Calorically perfect
air enters the three-dimensional domain at a freestream Mach number of 2.92. Analysis of the
turbulent boundary layer above the rearward-facing step indicates excellent agreement with
theoretical predictions. Mean velocity and pressure results are compared against Reynoldsaveraged
simulation results and against experimental data. These comparisons indicate a
significant improvement in the prediction of mean properties when using the hybrid approach
with turbulence recycling and strong agreement with experimental results.


CONSTRUCTION OF A FERMIONIC ATOMIC CLOCK FOR NASA’S
DEEP SPACE NETWORK

Megan Ivory, College of William & Mary
Atomic clocks are the most accurate time and frequency measurement devices existing today.
Current state of the art fountain clocks have limited accuracy due to atom-atom interactions. We
are building an atomic clock using ultracold fermions on a microchip which has the advantage of
superior accuracy by essentially eliminating atom-atom interactions. The Ultracold Atomic,
Molecular, and Optical Physics Lab at the College of William and Mary is building a dualspecies
apparatus for cooling and trapping rubidium and potassium bosons and fermions. Over
the past year, we have added significant capability to our apparatus: 1) We have constructed,
tested, and installed a magnetic transport system to carry our atoms from an initial MOT vacuum
chamber to the second chip vacuum chamber, 2) we have improved the lifetime of our rubidium
magnetic trap by an order of magnitude, 3) we have a rubidium dipole trap with lifetimes on the
order of 1s, 4) we have assembled the electronics for RF evaporation and the clock pulses, and 5)
we have reduced the temperature of our potassium atoms by nearly 2 orders of magnitude. We
present this progress towards a 40K fermion atomic clock with potential application in NASA’s
Deep Space Network.


TOWARDS RAPID RUNTIME RE-DEPLOYMENT AND OPTIMIZATION
FOR FRACTIONED SPACECRAFT

Hamilton Turner, Virginia Tech
This paper presents methods for adding optional software components to a Distributed Real-
Time Embedded (DRE) deployment optimization problem, and methods for at- tempting to
enable deployment of the maximal number of optional software components. By building upon
prior work that allows rapid deployment optimization, one can predict probability of success
with high confidence, and utilize that information to generate a lower bound on number of times
deployment of an optional component should be attempted. This paper also introduces three
algorithms for selecting which optional components should be attempted in a deployment, and
experimental data which shows that the order in which optional components are considered has a
high impact on the maximal number of optional components that can be included in a
deployment.


WELL-POSEDNESS AND LONG-TIME BEHAVIOR OF A WAVE
EQUATION WITH NONLINEAR DYNAMIC BOUNDARY CONDITIONS

Philip Jameson Graber, University of Virginia
In this paper we give a review of several results recently proved by the author on the
mathematical theory of acoustic/structure interactions governed by a coupled system of partial
differential equations. Such models arise in engineering applications including the control of
structural acoustic systems. We restrict our attention, for the most part, to the wave equation with
nonlinear acoustic boundary conditions. Using the theory of nonlinear dynamical systems, we
study the well-posedness of solutions (existence, uniqueness, and continuous dependence on the
initial data) as well as long-time behavior, decay rates, and finite time blow-up.


A DIFFUSION BOUNDARY ELEMENT METHOD FOR INTERIOR
ACOUSTICS WITH STRUCTURAL COUPLING

Joseph Corcoran, Virginia Tech
Recently, a new model for the propagation of sound in interior volumes known as the acoustic
diffusion model has been explored as an alternative method for acoustic predictions and analysis.
The model uses statistical methods standard in high frequency room acoustics to compute a
spatial distribution of acoustic energy over time as a diffusion process. For volumes coupled
through a structural partition, the energy consumed by structural vibration and acoustic energy
transmitted between volumes is incorporated through an acoustic transmission coefficient. In this
paper, Boundary Element Method (BEM) solutions to single and multiple volume models are
developed. The integral form of the 3-D acoustic diffusion model is derived using the Laplace
transform and Green’s Second Identity. The solution using the BEM is developed as well as an
efficient Laplace transform inversion scheme to obtain both steady state and transient interior
acoustic energy. Several volume configurations with varying geometry are examined as the
diffusion model and its BEM solution are analyzed and compared to conventional room
acoustics analysis methods. Advantages of this method over conventional methods such as
computational efficiency, applicability to high frequencies, and robustness to different problems
are revealed as the comparisons are made in different coupled volumes.


FREE-RUNNING VEHICLE CONTROL IN CFD ENVIRONMENTS
Ryan Coe, Virginia Tech
A study is currently underway to better understand and influence the maneuvering characteristics
of autonomous underwater vehicles (AUVs). A two-pronged approach, using traditional quasisteady
state-space modeling as well as maneuvering experiments performed in unsteady
Reynolds-averaged Navier-Stokes simulations (URANS), has been adopted to provide the
greatest possible insight into vehicle modeling. State-space models must be populated with
parameters describing the vehicle of interest. This paper focuses on the use of a virtual planar
motion mechanism (PMM) method to find hydrodynamic maneuvering characteristics within a
computational fluid dynamics (CFD) environment.

APPLICATION OF TUNABLE DIODE LASER ABSORPTION
TOMOGRAPHY

Kristin Busa, University of Virginia
Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement
technique for determining two-dimensional spatially resolved distributions of temperature and
species concentration in high enthalpy flows. TDLAT combines infrared laser absorption
spectroscopy with tomographic image reconstruction. Having previously been implemented at
the University of Virginia's Aerospace Research Laboratory supersonic combustion tunnel, the
TDLAT technique is now utilized for experimentation on NASA Langley’s Direct-Connect
Supersonic Combustion Test Facility. The tomographic reconstruction of an opaque object as
well as preliminary spectral data is presented. Ongoing experimentation on NASA Langley’s
facility is discussed.


DEVELOPMENT AND CHARACTERIZATION OF THIN FILM
SUPERCONDUCTING RADIO FREQUENCY SURFACES FOR
ACCELERATOR CAVITIES

William Roach, College of William & Mary
Superconducting thin films have the potential to improve the performance of particle
accelerators. Before these thin films can be implemented, a systematic study on structureproperty
correlations is necessary. Here, we present the characterization of niobium thin films
deposited onto both ceramic and metallic substrates. In particular, the film microstructure and
superconducting properties are examined. Our findings show that the strain and crystallographic
orientation of niobium films can adversely impact the transition between the superconducting
and normal state as well as the lower critical field.


AERODYNAMIC AND AEROELASTIC OPTIMIZATION OF
HARMONICALLY DEFORMING THIN AIRFOILS FOR MAV DESIGN

William Walker, Virginia Tech
The present paper addresses the aeroelastic optimization of a membrane wing. Aerodynamic
optimization of a deforming wing has been done in recent work by Walker, Patil, and Canfield.
The deformation shapes required for maximum thrust and thrust efficiency were calculated. In
the present work, the maximum thrust for the membrane wing is calculated by optimizing the
tension in the membrane so that the the aeroelastic deformation due to wing motion will lead to
optimal thrust and/or efficiency. A function which describes the variation of spanwise tension
along the chord is calculated. It is shown that one can always find a range of membrane tension
for which the flexible membrane wings performs better than the rigid wing. These results can be
used in preliminary flapping wing MAV design.

 


Aerospace

 

CHARACTERIZATION OF A DUAL-MODE SCRAMJET VIA
STEROSCOPIC PARTICLE IMAGE VELOCIMETRY

Brian Rice, University of Virginia
The following research paper presents an up to date status of the design and testing of a Dual-
Mode Scramjet model which is experimentally operated at UVa’s Aerospace Research
Laboratory. The demand for application of advanced optical measurement techniques has
facilitated the complete re-design of all test sections. The details of the design, analysis, and
capabilities of the DMSJ are the focus of the paper. Finite Element Analysis results are presented
for thermal stresses of various parts which provided confidence in design modifications.
Discussion of future work, in particular the application of the experimental Stereoscopic Particle
Image Velocimetry (SPIV) technique, will be presented. Lastly, initial pressure and temperature
measurements are reported. The successful operation of all test sections has allowed an ongoing
effort to build a comprehensive experimental database.


THE STUDY AND DEVELOPMENT OF ENERGY HARVESTING
VIBRATION ABSORBERS

Ryan Harne, Virginia Tech
Vibrational energy harvesting seeks to convert ambient energy into electricity when battery
replacement or line transmission is infeasible or impracticable. Electromechanical mass-spring
harvesters are designed to exhibit a resonance frequency close to the principal vibrational
frequency of the main or environmental system; excited near to resonance, the harvesters convert
the kinetic or potential energy into electricity by means of the electromechanical coupling
mechanism. Passive vibration control research has historically considered the mass-spring
system as a lightweight means by which to attenuate structural vibration. This research seeks to
unify the objectives of energy harvesting and structural panel vibration control by the study and
development of energy harvesting vibration absorbers (EHVA) capable of concurrently
satisfying both goals. New challenges are imposed in adopting this perspective, namely the
dynamic coupling of the EHVAs to the host structure and the development of versatile devices
which balance both objectives. Numerical modeling shows that the objectives are not in direct
opposition and experimental results show that careful EHVA design and employment adequately
meet both goals.


ONGOING WORK ON FAULT DETECTION AND ISOLATION FOR
FLIGHT CONTROL APPLICATIONS

Jason Upchurch, Old Dominion University
Modern aircraft flight control relies on a complex network of interacting systems. These systems
are safety critical systems, since a failure could have catastrophic consequences. It is therefore
necessary to detect and isolate faults in aircraft control system components such as actuators or
sensors before the fault is allowed to cause a system failure. Such detection and isolation could
potentially enable timely system reconfiguration and increase safety of flight operations.
Numerous fault detection and isolation techniques have been presented in the literature. This
paper demonstrates the ability of one such technique, observer-based eigenstructure assignment,
to detect and isolate faults by following implementation procedures and verifying its
effectiveness through simulation. The scope of this paper is limited to actuator faults and to the
simple case where all eigenvectors are assignable.
Future work will include a similar assessment of the technique's suitability for fault detection and
isolation in sensors and in the case where not all eigenvectors are assignable. The goal of this
work is to build a catalog of fault detection and isolation techniques and to devise an experiment
in order to assess each technique's relative advantages for flight control applications.


INTEGRATED CONTROL AND EFFECTOR DESIGN IN A MULTIDISCIPLINARY
DESIGN OPTIMIZATION OF A SUPERSONIC
TAILLESS LONG RANGE AIRCRAFT
Craig Morris, Virginia Tech
The increased complexity of next generation aircraft has popularized MDO as an aircraft design
tool. However, MDO efforts consistently neglect aircraft stability and control analyses beyond
simple static assessments. Not only does this limit the potential of the MDO to identify an
optimal design, but it also fails to assess the MIL-SPEC or FAR handling qualities requirements
the aircraft must achieve. In an effort to bring aircraft handling qualities and dynamic
performance into the MDO of a tailless supersonic aircraft, a dynamic stability assessment tool is
under development with the goal of automating the feedback control system design and
optimizing the aircraft's effector configuration. Optimal feedback control is currently achieved
through an inverse LQR solution using a stochastic optimization technique. A path forward to
more sophisticated methods under development is discussed, as is application of the technique to
a simplified elevator design problem on a more traditional aircraft configuration.


Graduate Research Fellows
Oral Presentations – Berkeley Room
Aerospace


MODELING CABLE-HARNESS EFFECTS ON SPACECRAFT
STRUCTURES

Kaitlin Spak, Virginia Tech
As designers aim to save on launch costs by using light-weight materials for space structures, the
cable harnesses that are mounted to these structures make up a greater percentage of the
structure’s mass than in past missions. Research has shown that the effects of cable harnesses on
the dynamic response of space structures may be significant, but there is not yet a reliable model
that can predict the changes in frequency response due to the structural mass of the cables. In
this paper, the author describes the development of two models to determine the fundamental
frequencies of cable-harnessed beams, one based on the Rayleigh-Ritz method and one based on
the distributed transfer function method. In addition, the author discusses the discrepancy
between experimental cable data and modeling a cable as an Euler-Bernoulli beam or string, and
how the cable could be modeled more accurately. The author also presents the experimental data
from the excitation of a cable-harnessed beam that will be used to validate the models, and what
trends can be observed from the experimental data. With further development, this research will
garner accurate models to accurately predict the natural frequencies and damping effects for
cabled space structures.


A TABU SEARCH APPROACH TO TACTICAL RUNWAY CONFIGURATION
MANAGEMENT

Jennifer Thorne, College of William & Mary
Tactical Runway Configuration Management (TRCM) plans runway configuration usage over a
pre-specified time interval to minimize arrival and departure delays while taking into account
constraints including flight patterns, taxi plans, aircraft, weather, and airport usage. Currently,
an exhaustive recursive search is used to test each runway configuration and determine the best
possible management scheme. A tabu search routine has been implemented to improve the
speed of the search for a high quality management scheme. When applied to a metroplex and
evaluated several times during the day, the TRCM optimization routine must run efficiently in
order to provide timely information to air traffic managers. The fundamental goal remains the
same for every airport: to select an airport configuration to maximize overall efficiency of
runways, airport surfaces, terminal airspace, and interaction of the airport with the National
Airspace System. However, the way in which runway configuration decisions are made, airport
surfaces are used, and terminal airspace is managed changes between airports. Despite these
differences, a TRCM optimization routine must be applicable to any airport without much
adjustment. Currently, the test cases are based on John F. Kennedy International Airport. We
report the benefits of using a tabu search over a recursive one.


WAVEFORM-AGILE SENSING FOR DETECTION AND TRACKING OF
UAVS USING RADAR
Amanda Daniel, Old Dominion University
In this paper we discuss the problem of radar waveform design from a new perspective that is
based on a vector channel model for the radar system. For a single waveform/single target
scenario we show that the capacity of the radar vector channel is identical to the mutual
information between the target impulse response and the received radar signal. Noting that a
water-filling strategy in designing the transmitted waveform implies maximizing channel
capacity, we acknowledge previous results on radar waveform design which proved that waterfilling
maximizes the mutual information between a target impulse response and the received
radar signal. We then discuss the radar waveform design problem in the context of multiple
waveforms and/or multiple targets, outlining similarities between the corresponding radar
scenarios and multiuser communication scenarios.

EXPERIMENTAL INVESTIGATIONS OF AIROIL THERMOSYPHONS
Christina Johnson-Pappas, University of Virginia
The effect of fill volume and evaporator temperature on the heat transfer performance, i.e. rate of
heat transfer, of airfoil-shaped thermosyphons for cooling applications is investigated. Two
copper-water thermosyphons, one with a cylindrical cavity and the other with a slot-shaped
cavity, were fabricated for testing. The rate of heat transfer for both thermosyphons was
measured at three fill volumes (expressed as a percentage of the volume of the evaporator
section): 0%, 60%, and 240% and for five evaporator temperatures: 250F, 275F, 300F, 315F,
and 325F. The condenser section was air-cooled in an open return wind tunnel with wind speeds
of 100 mph in the test section and an ambient temperature of 73F. The difference in heat
transfer rate between the 0% and 60% fill volumes for the slot is approximately 200 W at all
evaporator temperatures, while for the cylinder thermosyphon the difference is approximately 25
W. The rate of heat transfer was highest for both thermosyphons at 60% fill volume at the 325F
evaporator temperature. As fluid is added to the thermosyphons, the surface temperature rises
and the temperature distribution becomes more isothermal, which is indicative of thermosyphon
action taking place and explains the observed increase in performance.


EXPERIMENTAL AERO-HEAT TRANSFER AND DEPOSITION
UNDER REALISTIC ENGINE CONDITIONS

Colin Reagle, Virginia Tech
Erosion and deposition in gas turbine engines are functions of particle/wall interactions and
Coefficient of Restitution (COR) is a fundamental property of these interactions. COR depends
on impact velocity, angle of impact, temperature, particle composition, and wall material. The
current study attempts to characterize the fundamental behavior of sand at different impact
angles. A PIV system is used in the Virginia Tech Aerothermal Rig to measure velocity
trajectories of microparticles. A novel method is used that solves for impact velocity in a forced
flowfield by numerical methods. Two sizes of Arizona Test Dust and one of Glass beads are
impacted into a 304 Stainless Steel coupon. Free jet velocity is 27m/s at room temperature.
Impact angle varies from almost 90 to 25 degrees depending on particle. Mean results compare
favorably with trends established in literature. This utilization of this technique to measure COR
of microparticle sand will help develop a computational model and serve as a baseline for further
measurements at elevated, engine representative air and wall temperatures.



Planetary Science


OBSERVATIONS AND MODELS OF IAPETUS’ MICROWAVE
EMISSION

Paul Ries, University of Virginia
Iapetus was observed repeatedly with the Green Bank Telescope (GBT) at wavelengths between
3 and 11 mm, with the original intention being to use the data to determine the variation of
temperature with longitude. Instead, the data showed incredible wavelength-dependent deviation
from thermal emission, with Iapetus being only 30-40% as bright as the surface temperature
would lead one to expect . Numerous techniques were used to demonstrate that this incredible
dimness is real and not simply a bad calibration or other observational error. This value is the
among the lowest ever detected in the solar system, but can be achieved using physically realistic
ice models used to model microwave emission from snowpacks and glaciers on Earth. The
Microwave Emissivity Model for Layered Snowpacks (MEMLS) is used to try to constrain the
surface properties of Iapetus, yielding values for grain size and depth of the surface layer.
Additionally, longitudinal emissivity variation at these wavelengths shows the leading and
trailing hemispheres are different down to a depth of at least 100 cm on Iapetus.


HYBRID FLUID/KINETIC MODELING OF PLUTO’S THERMOSPHERE
Justin Erwin, University of Virginia
We concern ourselves with the problem of mass loss from a single component, 1D atmosphere,
in our case N2 loss from Pluto. Previous attempts have been solely fluid models with an upper
boundary condition far beyond the exobase. These solutions produce solutions with the flow
velocity always going sonic, sometimes above the exobase. We limit the use of the fluid models
to below the exobase where they are known to be valid and replace the upper boundary condition
with a DSMC model of the exosphere. Iteration between to two models produces a consistent
solution for the escaping atmosphere. We find only a small reduction in escape rate, but the flow
does not go sonic. From a parameter study of DSMC solutions by Volkov (2011), we know that
they escape rate is well approximated by Jeans theory, so we may use this theory from a finite
upper boundary. This model allows up to study a larger parameter space of heating rates and
other atmospheric parameters. We show that like the pure fluid models we find energy limited
escape rates, but without the sonic point or any assumption beyond the exobase. Finally we
propose a reason why escape rates are similar between models, and conclude that escape rate is
not a good determining factor for the existence of a sonic point.


IMPACT OF THE COMPACT GROUP ENVIRONMENT ON GALAXY
EVOLUTION

Lisa May Walker, University of Virginia
Compact groups of galaxies (CGs) are extremely dense groups of galaxies, where the galaxy
separation is approximately the size of a galaxy. These groups provide a local analog to galaxy
interaction in the early universe. The frequent and prolonged gravitational encounters in CGs
affect the evolution of member galaxies in myriad ways. To probe this, we have investigated the
mid-infrared (MIR) colors of galaxies in CGs, and find evidence for a bimodal distribution of
galaxies, with a dearth between quiescent and active galaxy colors. We speculate that the CG
environment fosters accelerated evolution of galaxies from star-forming and neutral gas-rich to
quiescent and neutral gas-poor, yielding a gap in MIR properties. We also analyze the optical
colors of CG galaxies and find a significant population of optically red galaxies and relatively
few galaxies with blue optical colors. Comparison with the MIR colors indicates that some of
these optically red galaxies are old, while others are active but suffer from extinction.
Comparison with the optical colors of field galaxies indicates that the stellar populations in
compact group galaxies tend to be older than in field galaxies.


MARS PLANETARY BALLOON ROVER DEPLOYMENT
Jake Tynis, Old Dominion University
This research has demonstrated how Martian weather patterns can be used in balloon systems,
incorporating autonomous navigation capabilities, to accelerate surface exploration. Polar
transport of the primary atmospheric constituent, carbon dioxide, drives the planetary weather
patterns, and nominal wind speeds are sufficiently high to facilitate planet-wide traverses.
Seasonal variations cause changes in weather patterns in a predictable manner that can be
exploited. These effects have been predicted using numerical simulations and verified starting
with the Viking Landers and subsequently from rover and orbital spacecraft. This research has
utilized the Mars-GRAM weather simulation program to explore wind conditions over candidate
surface launch locations throughout the Martian year. The data collected provides insight on
desirable base locations and nominal launch opportunities for serial robotic balloon missions. It
is possible to target a range of launch dates in order to reach selected downwind locations. For an
expedition launching in the Northern hemisphere, the prevailing winds are East to West most of
the year. However, near the summer solstice the prevailing winds flow West to East for a short
period. This change in flow direction is due to the sublimation of the polar ice caps. This effect
and others provide a logical basis for navigation using atmospheric sounding techniques and
buoyance control to effect navigation similar to sailing. Exploiting predictable weather variations
can lead to exploration of vast areas of the planet or access to otherwise inaccessible locations.

INFLUENCE OF CLIMATE CHANGE ON WAVE DISSIPATION
OVER CORAL REEFS AND SUBSEQUENT EFFECTS ON BEACH
MORPHOLOGY

Amy Grady, University of Virginia
Coral reefs play an important role in protecting shorelines by buffering wave energy; however,
reef ecosystems are highly vulnerable to the effects of climate change. To quantify the potential
effects of climate change-induced alterations to reef structure on coastal morphology, a U.S.
Geological Survey-developed Delft3D model is employed. This numerical model simulates the
coupled hydrodynamic and sediment transport processes of a Hawaiian fringing reef
environment. Preliminary findings indicate that the zone of maximum wave breaking is
translated inshore with simulated reef degradation. However, the depth-limited nature of the reef
flat environment prevents the resulting change in wave energy from reaching the coastal plain
deposit. Future modeling efforts will focus on simulating the degradation of coral reefs in
combination with other climatic changes expected in the future, such as increasing sea-level rise
and the magnitude and duration of storm waves.


Astrophysics


TESTING PROPOSED MECHANISMS FOR INTERSTELLAR
CHEMISTRY WITH RADIO INTERFEROMETRY

Joanna Corby, University of Virginia
New radio wavelength receivers are increasingly designed with broad bandwidth capabilities,
high sensitivity and high spectral resolution. The new availability of single dish radio telescopes
and interferometers with broadband capabilities allows great advancements in astrochemistry
enabling observations that will be critical in advancing astrochemical theory. I will discuss
planned and conducted observations that will be useful for addressing the formation of complex
molecules in space.


STRUCTURE AND COMPOSITION OF THE LOWER TROPOSPHERE
OVER THE HIMILAYAN FOOTHILLS OF NEPAL

Ksenia Brazhnik, College of William & Mary
Atmospheric Brown Clouds (ABCs) significantly reduce radiative transfer through the
atmosphere and thereby impact regional climate. Persistent ABCs form over the Indian
Subcontinent during the dry (December-February) and pre-monsoon (March-June)
seasons. They extend over hundreds of square kilometers, and migrate meridionally with
the monsoonal circulation between the Indian Ocean and the Tibetan Plateau. While
some ABC features can be characterized based on satellite- and ground-based
observations, in situ measurements from aircraft are required to resolve the primary
sources, physicochemical properties, and spatial evolution of ABCs, particularly over
complex terrain. We report here upon the unique observational data collected from an
aircraft over the foothills of the Nepal Himalayas (28oN, 84oE) during the dry and premonsoon
season of 2011. The measurements were collected between ground-level and
4500m amsl and include ozone, carbon monoxide, nitric oxide, black carbon (BC), sizeresolved
aerosol number concentrations, and corresponding meteorological conditions.
Aerosol and trace gas concentrations were found to be generally lower during the dry
season relative to the pre-monsoon season, and were also higher during the day relative to
morning. Higher concentrations of pollutants observed above the Seti River Valley
relative to comparable altitudes elsewhere suggest up-slope and up-valley transport of
pollutants from the city of Pokhara toward the Annapurna Himalaya. These processes
may have important implications for regional variability in radiative transfer and air
quality.

GEOMAGNETIC PERTURBATIONS OF EARTH FOLLOWING
SUBSTORM ONSET
Nicole Pothier, Hampton University
Large-scale maps of the surface perturbations in the Earth’s magnetic field following the onset of
substorms have been produced in order to determine the geomagnetic response of the Earth to
such disturbances. Data from 124 ground magnetometer stations in the northern hemisphere at
geomagnetic latitudes over 33 degrees were used. Upstream interplanetary magnetic field (IMF)
data from the ACE satellite were also used for sorting ground magnetometer data by orientation
of the IMF. Both datasets were compiled into 5-minute increments for an eight-year time period
(1998-2005). Pseudo-AU, AL, and AE indices were calculated from these data. These indices,
derived from a greater number of stations than the original, true AE indices, were used to
generate a list of 3151 substorms that extended from 1998-2005. Initiation times of the substorm
events were picked to align the data from each station for a spherical harmonic cap analysis at
each time step, to produce the statistically averaged response of the ground-based geomagnetic
perturbations of the Earth following the onset of substorms. This response was computed for
different values of the IMF orientation and peak magnitude of the substorm AL index. These
results will be used to supplement an existing model of geomagnetic perturbations.