Abstracts are listed in alphabetical order by the last name of the corresponding author.
| Student Author(s): | Brinkley, Matthew |
| Department(s): | Physics |
| Research Mentor(s): | David Aspnes/Physics |
| Title of Presentation: | Reflectance Difference Spectroscopy of Silicon Insulator Interfaces |
Using reflectance-difference spectroscopy we investigate the properties of as-deposited and rapid-thermal-annealed (111) and vicinal (111) silicon samples upon which oxide, nitride, and oxynitride films have been deposited. These spectra give information, nondestructively, about the nature of interfaces. In particular, measurements on vicinal samples provide insight about monolayer-height steps. We introduce a new method of determining such spectra by obtaining for each sample a set of spectra with the sample oriented every 30 degrees over a range of 180 degrees, and then Fourier transforming the set to obtain a final average. The spectra so determined exhibit structure that are related to strain associated with the steps.
| Student Author(s): | Carpenter, Aaron M. |
| Department(s): | Physical and Mathematical Sciences |
| Research Mentor(s): | John M. Blondin/Physics |
| Title of Presentation: | Thin Shell Instabilities in Planetary Nebulae |
Planetary Nebulae are spectacular glowing shells of gas ejected into space by the last gasps of dying stars and, with the advent of the Hubble Space Telescope, we are able to see the structures inside of these beautiful stellar objects. I have discovered a new type of instability which applies to the early stages of a newly formed planetary nebulae, when strong cooling leads to a thin shell of swept up gas. Using hydrodynamic simulations, I have been able to create models that accurately replicate the features observed through the HST. My simulations involve a spherically symmetric wind moving onto a uniform grid. By allowing the grid to expand, I am able to track the progression of the wind over time and follow the instability of the thin shell. This instability exhibits a strong resemblance to thestructures present in planetary nebulae. Using my simulations, I hope to be able to deduce how these structures are created and how they evolve over time. Ultimately, I hope to get a better understanding of how our own Sun will die in about five billion years.
| Student Author(s): | Cason,
Lisa
Clarke, Andy Ness, Gina |
| Department(s): | Statistics |
| Research Mentor(s): | William F. Hunt, Jr./Statistics |
| Title of Presentation: | An Investigation of Ozone and its Precursors Utilizing Photochemical Assessment Monitoring Station (PAMS) Data in Connecticut and New Jersey |
Ozone is a primary
constituent of photochemical air pollution. It is produced by the reaction
of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence
of heat and sunlight. Ozone is known to cause damage to the respiratory
and cardiovascular systems, as well as the skin and the eyes. For this
reason, there is an increased desire to measure the precursors that cause
ozone. The 1990 Clean Air Act required states to improve monitoring
systems for the emissions of NOx and VOCs to provide a more comprehensive
database so air pollution control agencies can evaluate, track the progress
of, and refine control strategies.
We obtained data from the United States Environmental Protection Agency
(USEPA) that included meteorological, VOC, NOx, and ozone measurements
from two PAMS sites located in Sherwood Island, Connecticut and New Brunswick,
New Jersey. Both sites are located in areas of maximum precursor
emissions. Our objectives were to answer several questions regarding
the relationship between ozone and its precursor pollutants. What
are the five most abundant compounds in the area? Do these compounds
show any day-of-the-week patterns? What are the levels of compounds
and meteorological conditions for ozone episode days? Can any compound
levels predict ozone?
Initially, we conducted a step-wise regression analysis of all the hourly
data. We were able to obtain around 70% of the variability in the
ozone measurements as a function of the VOCs, N0x compounds, and meteorological
variables. We then developed statistical models to predict the daily
maximum hour ozone as a function of the 6am-9am measurements of the ozone
precursors, wind speed and direction, maximum temperature, and maximum
solar radiation. With this model we were only able to explain approximately
48% and 65% of the variability in the maximum daily ozone value at two
sites.
| Student Author(s): | Chhak, Kettyah C. |
| Department(s): | Marine, Earth, and Atmospheric Sciences |
| Research Mentor(s): | Sethu Raman/Marine, Earth, and Atmospheric Sciences |
| Title of Presentation: | The Importance and Application of Quality Control on GLOBE Climatic Data |
The Global Learning
and Observations to Benefit the Environment (GLOBE) program officially
began in 1995 with 1,659 teachers, including 230 international teachers,
receiving GLOBE training. Today, the GLOBE program is a worldwide
network of approximately 10,000 schools in 96 countries. With the guidance
of research scientists, K-12 students and teachers make environmental observations
near their schools and report their data through the Internet. The
observations that the students make include air temperature, cloud cover,
precipitation, soil temperature and moisture, tree and grass biometry,
land cover, bud burst and surface water. The GLOBE program helps
increase environmental awareness in the students and the general public.
GLOBE temperature data were analyzed for all schools in order to see which
schools were updated and consistent in recording data in a monthly mode.
Updated, consistent schools with at least one year of data were then quality
controlled using procedures developed at the National Climatic Data Center
(NCDC). The quality control was carried out on several months of
data for each of the schools to check for internal temperature consistency
or content errors. A total of 53 schools in 16 different countries
met the quality control criteria. The application of quality control
on GLOBE data will allow scientists to confidently use the data in their
atmospheric or climatic research and analysis.
This project was completed with the support of the NCDC and the North Carolina
State Climate Office (SCO).
| Student Author(s): | Childs,
Peter
Ringer, Lee |
| Department(s): | Marine, Earth, and Atmospheric Sciences |
| Research Mentor(s): | Dev
dutta S.Niyogi/Marine, Earth and Atmospheric Sciences
Ryan P. Boyles/Marine, Earth, and Atmospheric Sciences Sethu Raman/Marine, Earth, and Atmospheric Sciences |
| Title of Presentation: | How Spatially Representative are North Carolina Climate Data?: A Case Study Using Field Observations at Different Spatial Scales |
Observations and climate
data records form one of the pivotal basis for establishing regional climate.
With increasing interest in understanding the nature and magnitude of climate
change, a critical question that needs to be addressed is: 'What is the
spatial
representativity of
such climate observations?'. That is, can the single station observation
data - which are often used in developing a climate summary - sufficiently
characterize a region? Data from meteorological stations were compiled
in groups representative of (i) within city (or microscale) comprising
of three observational sites at Lake Wheeler, NCSU Turf Field Lab, and
NCSU Arboretum; (ii) within a county (or mesoscale) comprising of the three
microscale and two other locations at Reedy Creek Field Lab, and RDU airport,
and (iii) over a region (or regional or a climate division scale) using
over 25 point observations. We analyzed temperature observations at the
different spatial scales using graphical and statistical approaches to
understand the biases and variability within the data. Results indicated
significant variability within the different stations, even under seemingly
homogeneous locations. The meteorological processes that might trigger
such variability and their representation in area - averaged / regional
estimates is also addressed.These findings are important to identify the
uncertainty in the climate change projections over North Carolinan domains,
and the need of addressing the mean and variability for developing regionally
representative climate sceanarios.
| Student Author(s): | Cook, James S. |
| Department(s): | Physics |
| Research Mentor(s): | Hans D. Hallen/Physics |
| Title of Presentation: | A Pulsed Jumping Ring Apparatus for Demonstration of Lenz' Law |
Lenz Law is often demonstrated in classrooms by the use of Elihu Thomson's jumping ring. However, it is ironic that a thorough analysis of the physics of the AC jumping ring reveals that the operation is due mainly to a phase difference, not Lenz Law. A complete analysis of the physics behind the AC jumping ring is difficult for the introductory student. We present a design for a pulsed jumping ring which can be fully described by the application of Lenz Law. Other advantages of this system are that it lends itself to a rigorous analysis of the force balances and energy flow. The simple jumping ring apparatus closely resembles Thomson s, but is powered by a capacitor bank. The jump heights were measured for several rings as a function of energy stored in the capacitors. A simple model describes the data well. Currents in both the drive coil and ring are measured and that of the drive coil modeled to illuminate some properties of the capacitors. An analysis of the energy flow in the system explains the higher jump heights, to 2 meters, when the ring is cooled.
| Student Author(s): | Copeland, Brian J. |
| Department(s): | Statistics |
| Research Mentor(s): | William F. Hunt, Jr./Statistics |
| Title of Presentation: | Standard Conditions of Temperature and Pressure vs. Local Conditions - What Does It Mean for Air Pollution Control? |
In the Environmental
Protection Agency's (EPA) Air Toxics Archive Data Base the measurements
are reported in standard temperature and pressure (STP, 25C, 760 mm Hg),
which, in 1996, some state governors said misrepresented the actual levels
of pollution in their state. That same year the Center for Air Pollution
Impact and Trend Analysis (CAPITA) preformed a study for Mr. Neil Frank
of the EPA on the impact of correcting PM10 measurements to local conditions.
This study states that a decrease of about 10 percent would be expected
in the winter months in the Northeast, and there could be decreases up
to 25 percent of reported values. The reason for these decreases
is mostly due to temperature, but those areas located in high elevations
will also experience decreases from the reported measurements.
In my research, I used data from the Air Toxis Archive Data Base, which
gives the pollutant identification code, the measurement of the pollutant,
in STP, and it's site, and the location of the site. Using the location
of the site, the elevation is found, and then the temperature for that
area can be added to change the measurement to one reported at a local
condition. Once the elevation and temperature for the site is found,
the local condition measurement is found for each month or season.
Seven toxics were looked at, benzene, lead, chromium, cadmium, perchloroethylene,
acetaldehyde and formaldehyde, at sites across the US. These sites
show the same decreases that the PM10 data did, with values dropping about
10-15 percent, with as much as a 28 percent decrease at some monitoring
sites. With levels dropping this much, it will save states millions
possibly billions of dollars in air pollution control costs. Further
analysis is needed to look at more sites across the US.
| Student Author(s): | Crotty, Michael T. |
| Department(s): | Statistics |
| Research Mentor(s): | William F. Hunt/Statistics |
| Title of Presentation: | Spatial and Temporal Analysis of Sulfates, Sulfur Dioxide and Other Pollutants Compared with Sulfur Dioxide Emissions in the Eastern United States, 1990-99 |
Spurred on by the Clean Air Act amendments of 1990, ambient air pollution in the United States has decreased despite dramatic increases in the US population, vehicle miles traveled, and gross domestic product. The Clean Air Status and Trends Network (CASTNet), a network of continuous ambient air concentration monitors in the eastern US, has collected air quality data for six pollutants at 34 rural sites for over 10 years. The CASTNet sites are remotely located to study the impact of pollution transport. The data from the 34 rural sites, combined with continuous hourly emissions data from power plants in the Acid Rain Program over the same decade, show significant improvements in air pollution when statistical techniques are applied to investigate trends over the decade. Sulfur dioxide and sulfate concentrations at the 34 rural sites decreased 20-30%, while sulfur dioxide emissions decreased 23% at those corresponding states' electric power plants. Particulate ammonium concentrations decreased 16%. Other pollutants had less dramatic trends. These trends vary from site to site, however. Analysis of these variations shows that there is a correlation between sites that depends on the distance between sites. Three sites were chosen arbitrarily to represent three different regions of the eastern US: the Northeast (a site in New York), the Southeast (a site in Georgia), and the Mid-East (a site in Indiana). All sites were then grouped into the three regions and investigated within these regions to assess spatial relationships. Some work on analyzing the trends themselves at each site has also been undertaken, mainly comparing the trends graphically. In summary, the analysis shows how reductions in pollutant emissions from fossil fuel power plants have resulted in cleaner air, which in turn brightens the outlook on finding solutions to reduce the impact of fossil fuel power plants on global warming.
| Student Author(s): | Ellis, Robert H. |
| Department(s): | Marine,
Earth and Atmospheric Sciences
State Climate Office of North Carolina |
| Research Mentor(s): | Sethu Raman/Marine, Earth and Atmospheric Sciences |
| Title of Presentation: | Effect
of Soil and Vegetation Characteristics on Mesoscale
Precipitation in the Sandhills Region of the Carolinas |
The Sandhills region
extends from southeastern North Carolina through South Carolina and into
eastern Georgia, and forms the boundary between the Piedmont and Coastal
Plain regions. North Carolina counties include Lee, Moor, Harnett, Richmond,
Hoke and Scotland. In South Carolina this area is more well defined as
it runs parallel to the coast through the mid point of the state, including
the city of Columbia down through Augusta, Georgia. This region is
so named because of its distinct rolling hills of sandy soil and scrub
forests.
Hypothesis: The Sandhills region exhibits characteristics in which surface
conditions become more favorable for convection. The sandy soil in
this area drains fairly well, while heating quickly. It is adjacent to
regions with clay or clay-loam soil to the west. These sharply differing
soil characteristics sets up an abrupt change in albedo and surface and
subsurface heat capacity which in turn can cause horizontal gradients
in surface sensible and latent heat fluxes. Such gradients generally cause
mesoscale circulations acting as triggers for weather events such as cold
front passages, and coastal fronts in winter,and for sea breeze fronts
in summer. Enhanced precipitaion over this region is a possible effect.
This mesoscale process will be studied using monthly climatological precipitation
and temperatures for various stations.
Results from this study will be of great benefit to issues related to farming,
tourism, and air quality among others.
| Student Author(s): | Grissom, Jason A. |
| Department(s): | Statistics |
| Research Mentor(s): | William F. Hunt, Jr./Statistics |
| Title of Presentation: | Assessing Adverse Health Risks in the U.S. Foreign Service: A Comparison of Particulate Matter Levels in the World's Megacities |
Particulate matter
(PM) pollution has been closely linked with a variety of negative health
conditions. Prolonged exposure to these particles in the air (which measure
fewer than 10 micrometers) can result in asthma, decreased lung function,
aggravation of cardiopulmonary diseases and premature death. Fortunately,
strict enforcement of air quality standards by the U.S. Environmental Protection
Agency has protected most Americans from these risks in recent years. In
many other nations, however, standards for particulate matter emissions
by manufacturers are either nonexistent or go unenforced, placing both
those nations' citizens and U.S. citizens living abroad at risk for pollution-induced
diseases. The U.S. State Department, for whom this study was conducted,
has initiated an effort to compare the relative severity of PM pollution
in the US with worldwide megacities. A number of questions
arise, such as how do you deal with State Department employees who are
exposed to high levels of air pollution? Do the risks to employees
and their families warrant a change in the rotation system whereby agents
in the Foreign Service receive their placements or monetary compensation
("hazardous duty pay")?
This research project supports the exploration of those issues by providing
scientific comparison of air quality between major world cities. No published
uniform standard and measurement method currently exists for making those
comparisons since there is no uniform worldwide standard and air monitoring
method for collection of air quality data. Instead, the author develops
a system of ratio estimates for converting various countries' measurement
units to common units that can be compared to one another. In the second
phase of analysis, the author provides four ranked listings of ratios between
estimated PM levels in State Department post cities and 1) PM levels in
New York City; 2) PM levels in Los Angeles; 3) PM levels in Washington,
DC; and 4) the minimally acceptable national standard. The result is a
simple tool for comparing particulate matter pollution across international
boundaries.
| Student Author(s): | Harrington, Daric R. |
| Department(s): | Statistics |
| Research Mentor(s): | William
F. Hunt, Jr./Statistics
William Swallow/Statistics |
| Title of Presentation: | Controlling Air Pollution: How Accurate Is Emissions Testing? |
Emission testing is
critical for enforcing pollution emission limits to minimize the impact
of air pollution on the public. This study was conducted to evaluate
quality control and quality assurance procedures associated with emissions
testing. This work was done under the direction of Mr. Terry Harrison
with the Emission Measurement Center of the U. S. Environmental Protection
Agency. Quality assurance is evaluated in terms of how accurately
and precisely a dynamic spiking system would quantify analytes of interest
in a specific test matrix. Dynamic analyte spiking is a technique
used for quality assurance evaluation of extractive sampling and analysis
(S&A) systems in the field by assessing the performance of an extractive
instrumental S&A system for a given sample matrix. By observing
the S&A response before, during, and after dynamic spiking of the analyte
into the sample matrix, the tester obtains information on the ability of
an S&A system to accurately transport a sample to the analyzer and
perform analysis.
The laboratory experiment tests were performed as a Latin Square with the
row element being the run number (1, 2, 3) and the column element being
the time or order of evaluation (1st, 2nd, 3rd). The treatment is
the concentration (low, medium, high). In other words, each treatment
appears only once in each column and row, so that each run has the treatments
tested in a different order. By setting up the experimental design
like this, we can test to see if the order in which we test the concentrations
is significant. In addition, two substances, a liquid and a gas,
were each used in two systems. One system spiked the two substances
simultaneously while the other system spiked them sequentially.
Results showed no significant effect of order, concentration, or system.
The dynamic spiking system proved to be within 10% relative difference
of the actual value over 95% of the time. Continuing research is
being performed to improve the accuracy and precision. This approach
will ensure the validity of the emissions test results and, in so doing,
maintain the integrity of control programs to protect the public health.
| Student Author(s): | Hopping,
Albert E.
Nusz, Gregory J. |
| Department(s): | Physics |
| Research Mentor(s): | Hans D. Hallen/Physics |
| Title of Presentation: | Biologically Compatible Probes via Self-Assembled Monolayers |
Cell studies require the ability to insert and remove probes without damage to either the probe or the cell. Probes include pulled capillaries, etched optical fibers and aluminum coated etched optical fibers. These probes may break off in the cell or destroy the cell upon removal due to cellular material adhering to the probe. We use the self-assembled monolayer (SAM) octadecyltrichlorosilane (OTS) to coat the probes thus preventing adhesion of cellular material. The ability to reuse tips will reduce cost and increase the efficiency of biological studies.
| Student Author(s): | Hutchison, Kibri D. |
| Department(s): | Marine, Earth and Atmospheric Sciences |
| Research Mentor(s): | Dev dutta S. Niyogi/Marine, Earth and Atmospheric Sciences |
| Title of Presentation: | Developing Top-Down/Bottom-Up Couplings of Surface and Subsurface Variables for Ecosystem Studies: Relations Between Air and Soil Temperatures Using Field Observations |
Traditionally, ecosystem
and climate studies have focused on surface observations because of the
relative ease in measuring them. However, many ecological problems such
as those associated with carbon sequestration, and biosphere - atmosphere
interactions, require information on the subsurface variables such as soil
moisture and soil temperature. However, there is a paucity of subsurface
data; hence, there is a need to develop such information based on more
easily available, surface observations. We developed such a coupling based
relation for air and soil temperature over North Carolina.
We used two years worth of daily observations of air and soil temperature
at ten different locations for our analysis. The data were first
quality controlled, and then graphically and statistically analyzed to
understand their co-variance. These data were then used to develop correlation
equations between air and soil temperature. These relations were
then used to generate soil temperature from air temperature data and validated
with concurrent soil temperature measurements. The variability in the air
and soil temperature coupling was further analyzed with three independent
factors / groups - soil texture, land use, and geographic location.
These factors are critical input variables to terrestrial ecosystem / land
surface models; hence, their impact on the surface - subsurface relations
is of particular interest.
The soil texture and land use data are compiled at different scales (corresponding
to those used in large scale / regional models, and in high resolution
GIS studies). The variability in the outcome of the micro versus regional
scaling is also addressed as a critical issue in understanding the role
of surface processes in climate and ecosystem studies. Our study resulted
in developing a simple air and soil temperature based relation that can
be used in terrestrial ecosystem analyses.
| Student Author(s): | Lakhani, Chirag |
| Department(s): | Physics |
| Research Mentor(s): | Chueng R. Ji/Physics |
| Title of Presentation: | Classical Chromodynamic Approach to Study of Hadrons |
The advances of group theory in particle in physics have allowed for better understanding of the internal symmetries of these particles. The groups of particular interest in particle physics the Lie groups SU(2) and SU(3) whose representations have been fundamental of understanding spin and flavors of quarks respectively. With the success of Maxwell's equations in understanding the behavior of classical electromagnetic phenomena, the approach to the creation of classical chromodynamics is to develop a set "Maxwell's Equations" that depict the interactions of the internal behaviors in the hadrons made of quarks. The classical electrodynamic Maxwell's equations are written in a U(1) form, the purpose of the project is to transform these classical U(1) equations into a SU(2) form to understand the difference and similarity from classical electrodynamics and develop methods to provide an insight of the behavior of the quarks inside of hadrons.
| Student Author(s): | Mayer, Alex C. |
| Department(s): | Physics |
| Research Mentor(s): | Jacqueline Krim/Physics |
| Title of Presentation: | Recent Advances in the Study of Superconductivity- Dependent Sliding Friction |
An electronic component of nanoscale friction was discovered several years ago, which lead to a number of new theories and experiments. A detailed description of recent advances in the studyof superconductivity-dependent sliding friction of nitrogenfilms adsorbed onto a quartz crystal microbalance with lead electrodesis presented here.
| Student Author(s): | McDuffee, Michael R. |
| Department(s): | Mathematics |
| Research Mentor(s): | Ron Fulp/Mathematics |
| Title of Presentation: | Holonomy Groups on Abstract Manifolds and Fiber Bundles |
In
studying certain aspects of holonomy theory and their connections to other
areas of mathematics, it is possible to find simpler and more comprehensible
representations of important physical concepts. Modern physics has
found that many of the most basic physical properties can be formulated
as gauge fields, generalizations of electromagnetic fields that include
most boson fields. These gauge field theories can be formulated mathematically
as connections on a principle fiber bundle. A principle fiber bundle
consists of two manifolds and a Lie group, called the structure group of
the bundle.
In order to quantize such theories, one must consider all of the gauge
fields over some spacetime manifold with a certain structure group.
Quantum mechanical states, for example, use this type of formulation.
However, the structure group in these
circumstances
is infinite dimensional, as is the group that acts on it. The necessary
mathematical structure using these groups contains singularities, and thus
is very difficult to work with. Because of these difficulties, physicists
are interested in finding some friendlier representation.
It may be possible to find simplifications of this and other problems by
studying holonomy groups on manifolds relevant to the problems. We
have begun by examining the properties of an abstract connection on a generalized
manifold, paying special attention to the covariant derivative. Starting
with the corresponding definitions on a Riemannian manifold, we have analyzed
the abstraction of these principles. We have also studied properties
of geodesics on manifolds and its relation to curvature. These properties
are fundamental in describing the holonomy group of the manifold.
| Student Author(s): | Pratt, Aaron S. |
| Department(s): | Marine, Earth, and Atmospheric Sciences |
| Research Mentor(s): | Sethu Raman/Marine, Earth, and Atmospheric Sciences |
| Title of Presentation: | An Analysis of the Variation of Extreme Values of Precipitation, Maximum Temperatures and Minimum Temperatures in North Carolina for Fifty Years (1949-1998) |
Much debate has been made about climate change and its potentially serious consequences. A significant amount of this debate focuses on whether the planetary climate will change in a beneficial manner, or in a devastating manner. In particular, scientists want to know if the climate could become more extreme, resulting in vast temperature and precipitation swings that could significantly affect society. The purpose of this study is to study seasonal extremes in monthly maximum temperatures, minimum temperatures, and precipitation for North Carolina from 1949-1998, and analyze any temporal and spatial variations. Seventy-five COOP stations were used for precipitation, while 58 were used for maximum/minimum temperatures. These are the stations maintained by cooperative observers where long, continuous records of temperatures and precipitation are available. The seasons were selected such that January-March is winter; April-June is spring, July-September represent summer, and October-December represent fall. Precipitation extremes ranged from 6 to 30 inches, maximum temperature extremes from 89 to 96o F, and minimum temperature extremes from 10 to 27o F. Preliminary analyses showed the spatial coverage of extremes at expected areas of NC (i.e., coldest temperatures in western NC, and highest temperatures in coastal plains of NC). The analysis also showed evidence of an increasing trend in winter maximum temperatures and a decreasing trend for winter minimum temperatures. Precipitation data for winter also showed a 20-30 year cycle. Possible relationships of trends and cycles to the North Atlantic Oscillation and the Pacific Decadal Oscillation will also be discussed.
| Student Author(s): | Sabourov, Amanda L. |
| Department(s): | Physics |
| Research Mentor(s): | John
H. Kelley/Physics
Caroline D. Nesaraja/Physics Brendan T. Crowley/Duke University, Physics Konstantin V. Sabourov/Duke University, Physics Henry R. Weller/Duke University, Physics Kara J. Keeter/Idaho State University, Physics Richard M. Prior/North Georgia College and State University, Physics Mark Spraker/North Georgia College and State University, Physics |
| Title of Presentation: | Development of a Compton Scattering Beam Flux Monitor |
A beam flux monitor is being developed for use with the High-Intensity Gamma-ray Source (HIGS) at the Triangle Universities Nuclear Lab / Duke Free Electron Laser Laboratory (TUNL/DFELL). At the high beam intensities and energies which will soon become available, innovative methods for beam flux measurements are required. One such method is the use of a NaI detector at a small angle relative to the beam axis, which will detect the photons that are Compton-scattered from a thin target. By locating the scattering target downstream from any other experimental apparatus, this method allows monitoring of the beam flux in parallel with experimental data acquisition.
| Student Author(s): | Sellers, Wendy M. |
| Department(s): | Marine, Earth and Atmospheric Sciences |
| Research Mentor(s): | Sethu Raman/Marine, Earth and Atmospheric Sciences |
| Title of Presentation: | Assessing Air Pollution Dispersion Potential in the Research Triangle Area Through Analysis of Wind Data |
Wind speed and direction are important factors in determining the transport and dispersion of air pollution. The purpose of this research is to analyze the air pollution dispersion potential at locations across the Research Triangle Park area. Wind speed measurements at 10 meters above ground level will be obtained from automated weather stations in Wake County and surrounding counties for the year 2000. Wind speed values at each station will be averaged monthly and daily. Additionally, daytime and nighttime variations in winds will be assessed. A daytime wind speed from 6am to 6pm will be calculated, along with a nighttime wind speed from 6pm to 6am. In order to account for the surface heating cycle, data will also be classified based on sunrise and sunset times. These day and night values will then be averaged monthly for each station. Wind characteristics of urban stations will be compared with those from the rural stations to delineate urban heat island and roughness effects.
| Student Author(s): | Soo
Hoo, C.
Paquin, D. |
| Department(s): | Physics
Davidson College |
| Research Mentor(s): | John M. Blondin/Physics |
| Title of Presentation: | Convective Instability in Core-Collapse Supernovae |
We are investigating the effects of asymmetry on convective instability in core-collapse supernovae. We use the numerical hydrodynamics code, VH-1, to simulate the shock wave resulting from a core-bounce of a Type II (core-collapse) supernova. We perform simulations in both one and two dimensions with symmetric and various asymmetric density perturbation conditions. Simulations showed that for asymmetric conditions there are significant increases in convective instability within milliseconds after bounce with only minor density perturbations. Diagnostics include animations of entropy, angular velocity and vorticity, as well as graphical analysis of average shock radius and the kinetic energy of turbulence.
| Student Author(s): | Speer,
Nathan J.
Kiss, Miklos Z. |
| Department(s): | Physics |
| Research Mentor(s): | Dale
E. Sayers/Physics
Z. Zhong/National Synchrotron Light Source M. Campie/Rush University R. Summer/Rush University |
| Title of Presentation: | Studying Bone using Diffraction Enhanced Imaging |
We are investigating the possible advantages of using diffraction enhanced imaging (DEI) to study defects in bone as compared to conventional x-ray radiography. Using x-rays from a synchrotron radiation source we examined two samples of bovine cortical bone, a test specimen and a control specimen. The test specimen was fatigued in compression to 40MPa at 2Hz to a failure criterion where the initial displacement increased 140%. For both samples we took radiographs as well as diffraction enhanced images at several positions on the rocking curve of the analyzer crystal. The test sample and the control samples appeared to the unaided eye to be identical in color and texture. However, the DEI images did show a substantial difference in texture between the two samples, which may be related to the changes in the bone under stress. We are currently investigating methods for analyzing the data.
| Student Author(s): | Tanner, Paul J. |
| Department(s): | Physics |
| Research Mentor(s): | David G. Haase/Physics |
| Title of Presentation: | Nuclear Orientation Thermometry |
The emphasis of the work performed for the duration of the summer was to study the phenomenon of Nuclear Orientation (NO) as it pertained to determining temperature in the polarized target chamber of a 3He4He dilution refrigerator. The work was performed with the Polarized Target group at the Triangle Universities Nuclear Laboratory (TUNL). The properties of the 60CoCo(hcp) source and the principles governing NO are explained. Measurements indicate a target chamber temperature of ~ 21 mK was obtained.
| Student Author(s): | Wood, David K. |
| Department(s): | Physics |
| Research Mentor(s): | Dale
E. Sayers/Physics
Robert J. Nemanich/Physics |
| Title of Presentation: | Formation of Cobalt Disilicide Films on (3X3) 6H-SiC(000-1) |
We have studied the
formation of CoSi2 thin films on the C-terminated (000-1) face of
6H-SiC. The films were produced using sequential deposition of Co and Si
layers on 6H-SiC(000-1) with a (3x3) surface reconstruction. Films were
annealed to surface temperatures of 450oC, 550oC,
and 650oC. The topography and composition of the films were
studied using x-ray absorption fine structure, atomic force microscopy,
and x-ray diffraction. Films grown by sequential deposition and annealed
at 450oC and 550oC contained highly oriented CoSi2
with some island formation. Films annealed at 650oC were polycrystalline
and have large CoSi2 islands. Films formed at 450oC and 550oC
indicated a higher level of epitaxy than similar films grown on the Si-terminated
(0001) face of 6H-SiC.
| Student Author(s): | Woodside,
Kathryn E.
Woolfolk, Wendy |
| Department(s): | Statistics |
| Research Mentor(s): | William F. Hunt/Statistics |
| Title of Presentation: | Protecting the Public Health: Forecasting Fine Particular Matter in Forsyth County |
Particulate matter (PM) is one of the major air pollutants today. PM includes both solid particles and liquid droplets from the air. Fine PM are the particles that are smaller than 2.5 micrometers. These particles can accumulate in one’s respiratory system and cause or aggravate many health problems. Because of its danger, being able to predict PM fine measurements would be helpful. With predictions, people with respiratory diseases, the elderly, and children would know whether their health was in danger before going outdoors. Our objective was to come up with a summer and a winter model to predict PM fine using meteorological data, ozone data, and yesterday’s PM fine measurements. All of our data came from Forsyth County and it was provided by our clients at the Forsyth County Department of Environmental Affairs. We used multiple regression to come up with the two forecasting models. We used various variables such as the maximum temperature, the average temperature, dew point, wind speeds, the maximum ozone from eight sites around Forsyth County, and yesterdays PM fine measurements. We divided our data into winter (October-April) and summer (May-September). We then used backward regression to come up with a model that only included variables that were significant at the 5 percent level. Our summer model was much better. The regression equation for winter with three variables explains only 44 percent of the variation of PM fine. Whereas the summer model with five variable explains 76 percent of the variation of PM fine. We are currently considering other models with variables that consider the interaction between various variables and variables that have been transformed. By including these in the model, we hope the accuracy of the winter model will increase. Our presentation will further explain our models, how they were formed, and show their accuracy.
| Student Author(s): | Yablonsky, Richard M. |
| Department(s): | Marine,
Earth, and Atmospheric Sciences
Chemistry |
| Research Mentor(s): | Viney
P. Aneja/Marine, Earth, and Atmospheric Sciences
Tim Hughes/Environmental Verification and Analysis Center, Norman, Oklahoma |
| Title of Presentation: | Wind Power in Oklahoma: Using WindMap Software to Estimate the Wind Resource Potential of Southwestern Oklahoma |
Wind power in Oklahoma
is an untapped resource. The purpose of this research was to use
a software package called WindMap and to perform a threefold assessment
of its effectiveness in determining Oklahoma’s wind resource potential.
First, WindMap’s ability to estimate wind speeds was evaluated. An
R2 correlation of 0.4168 was found between the data points that were used
as the basis for the wind speed estimations, so given the input parameters
used, WindMap’s wind speed estimations were mediocre at best. The
results show that the accuracy of the surface roughness values in the study
area had a large affect on the software’s output. The proximity of
a station’s nearest neighboring stations and localized terrain effects
also affected the software’s accuracy, but the connection was not as clear
with these variables as with surface roughness. It was concluded
that WindMap may have the ability to estimate wind speeds and wind power
density well enough to indicate good regions for installing wind turbines,
but more testing needs to be done using a broader range of input parameters.
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