Digital Commons Network^™

Near-Field Intensity Correlations In Semicontinuous Metal Films, K. Seal, H. Noh, Alexey Yamilov, A. K. Sarchev, D. A. Genov, V. M. Shalaev, Z. C. Ying, Hui Cao

Physics Faculty Research & Creative Works

Spatial intensity correlation functions of semicontinuous metal-dielectric films of varying metal concentration, p, were obtained from near-field microscopy. The data shows a transition from propagation to localization and back to propagation of optical excitations with increase in p.

Half-Metallicity And Efficient Spin Injection In Aln/Gan:Cr (0001) Heterostructure, Julia E. Medvedeva, X. Y. Cui, C. Stampfl, N. Newman, Arthur J. Freeman

Physics Faculty Research & Creative Works

First-principles investigations of the structural, electronic, and magnetic properties of Cr-doped AlN/GaN (0001) heterostructures reveal the possibility of efficient spin injection from a ferromagnetic GaN:Cr electrode through an AlN tunnel barrier. We demonstrate that Cr atoms segregate into the GaN region and that these interfaces retain their half-metallic behavior leading to a complete, i.e., 100%, spin polarization of the conduction electrons. This property makes the wide band-gap nitrides doped with Cr to be excellent candidates for high-efficiency magnetoelectronic devices.

Microwave Permeability Of Co₂ Z Composites, Konstantin Rozanov, Marina Koledintseva, Z. W. Li, L. F. Chen

Physics Faculty Research & Creative Works

The microwave permittivity and permeability of Co2Z barium ferrite composite samples are measured as functions of frequency and volume fraction of the ferrite. Magnetostatic properties of the bulk ferrite are determined. This allows Snoek's law [J. L. Snoek, Physica 14, 204 (1948)] to be verified by comparing the microwave and magnetostatic Snoek's constants. The modification of Snoek's law for hexagonal ferrites suggested recently by Acher et al. [Phys. Rev. B 62, 11324 (2000)] is also verified. Acher's constant is found from microwave measurements to agree with the value calculated from the magnetostatic properties of bulk ferrite, but microwave and magnetostatic …

Near-Field Intensity Correlations In Semicontinuous Metal-Dielectric Films, K. Seal, A. K. Sarychev, H. Noh, D. A. Genov, Alexey Yamilov, V. M. Shalaev, Z. C. Ying, Hui Cao

Physics Faculty Research & Creative Works

Spatial intensity correlation functions are obtained from near-field scanning optical microscope measurements of semicontinuous metal-dielectric films. The concentration of metal particles on a dielectric surface is varied over a wide range to control the scattering strength. At low and high metal coverages where scattering is weak, the intensity correlation functions exhibit oscillations in the direction of incident light due to excitation of propagating surface waves. In the intermediate regime of metal concentration, the oscillatory behavior is replaced by a monotonic decay as a result of strong scattering and anomalous absorption. Significant differences in the near-field intensity correlations between metallic and …

Role Of Embedded Clustering In Dilute Magnetic Semiconductors: Cr Doped Gan, Julia E. Medvedeva, B. Delley, N. Newman, C. Stampfl, X. Y. Cui, Arthur J. Freeman

Physics Faculty Research & Creative Works

Results of extensive density-functional studies provide direct evidence that Cr atoms in Cr:GaN have a strong tendency to form embedded clusters, occupying Ga sites. Significantly, for larger than 2-Cr-atom clusters, states containing antiferromagnetic coupling with net spin in the range 0.06-1.47 µB/Cr are favored. We propose a picture where various configurations coexist and the statistical distribution and associated magnetism will depend sensitively on the growth details. Such a view may elucidate many puzzling observations related to the structural and magnetic properties of III-N and other dilute semiconductors.

Tunable Conductivity And Conduction Mechanism In An Ultraviolet Light Activated Electronic Conductor, Mariana I. Bertoni, Thomas O. Mason, Julia E. Medvedeva, Arthur J. Freeman, Kenneth R. Poeppelmeier, B. Delley

Physics Faculty Research & Creative Works

A tunable conductivity has been achieved by controllable substitution of an ultraviolet light activated electronic conductor. The transparent conducting oxide system H-doped Ca12-xMgxAl14O33 (x=0,0.1,0.3,0.5,0.8,1.0) presents a conductivity that is strongly dependent on the substitution level and temperature. Four-point dc-conductivity decreases with x from 0.26 S/cm (x=0) to 0.106 S/cm (x=1) at room temperature. At each composition the conductivity increases (reversibly with temperature) until a decomposition temperature is reached; above this value, the conductivity drops dramatically due to hydrogen recombination and loss. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Mg-substituted …

Crystallization Conditions Of High Silica Rhyolite In The Wichita Mountains, Oklahoma, Ryan Davidson

Opportunities for Undergraduate Research Experience Program (OURE)

Crystal size distribution analysis is being applied to the Carlton Rhyolite of the Wichita Mountains of southwestern Oklahoma. Field observations, descriptions, and sample collection has been completed. Rock samples were cut into slabs and then scanned. From these images the phenocrysts are outlined in CorelDrawl 1 and analyzed using Scion Image to obtain crystal size. Distribution analysis is done using CSD Corrections 1.36 (Higgins 2002). This, in combination with the visible phenocrysts, seems to indicate a flow style of deposition, rather than an airfall.

Measurements Of Combustion - Generated Particulates, Matthew F. Chandler

Opportunities for Undergraduate Research Experience Program (OURE)

Soot particles produced by combustion processes can have a significant impact on such areas as environmental pollution and respiratory hazards. The particulate emissions from high-altitude aircraft engines are especially important. Once the characteristics of the soot aerosols are known, further investigation may determine what methods can be used to control the production of such particulates. Particulate size, concentration, and surface area are factors used to determine its impact on the environment. The differential mobility instruments used for this project are capable of measuring particle sizes from 5 nm to 1000 nm based on the corresponding electrical mobility. The measurements from …

Secondary Reinforcement Requirements For Frp Reinforced Panels, Nathan Branham

Opportunities for Undergraduate Research Experience Program (OURE)

Concrete bridge decks are exposed to some of the harshest weather, that any structural element experience. Regular concrete slabs that rest on earth, are exposed to the same environmental effects, but they also have the ground to help heat them in extreme winter. Bridge decks are surrounded by cold air. This cold environment cause transportation department to cover concrete bridge decks with deicing salts to dissolve ice present on the decks. These deicing salts cause major problems with reinforced concrete. Cracking of concrete bridge decks impose even larger problems, because the cracks allow the chlorides from deicing salts to infiltrate …

Scour On Bridge Piers Due To Flood Waves, Gaston E. Ferrari

Opportunities for Undergraduate Research Experience Program (OURE)

A mathematical solution is presented for approximating the time-dependent scour response to flood waves. This solution is in the form of a convolution integral involving a timevarying scour-forcing function and an exponential scour-response function. In this report, an idealized triangular hydrograph is considered from which an analytic solution is obtained, and also an analytical hydrograph is used from which an analytical solution is also obtained for scour associated with flood waves.

Because of the exponential scour rate, the response obtained from the convolution method is found to lag the scour forcing in time and is damped relative to the maximum …

Preliminary Experiments On Boron Water Chemistry Fundamentals In Connection To Axial Offset Anomaly In Light Water Reactors, Adam Chadek

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.

High Pressure Water Jet Contaminant Remediation Of Intertidal Sediment Via Distributed Granular Activated Carbon, Rachel Dilly

Opportunities for Undergraduate Research Experience Program (OURE)

Hunters Point Naval Shipyard lies on western intertidal coastline and is designated as a Superfund site. Studies indicate sediment dwelling organisms that usually thrive in this intertidal area are now suffering and dying from PCB toxins. Experts have discovered that PCBs adsorb onto Granular Activated Carbon (GAC) particles, a material commonly used for contaminant remediation. Using a water jet, the GAC can be distributed in situ throughout the top IO cm. of sediment. Research measures will include reproducing the natural, intertidal habitat in the UMR High Pressure Water Jet Laboratory. Specifically, to realize optimal benefits from the remediation process, a …

Tundra Orbit Constellation, Natalie Davidson

Opportunities for Undergraduate Research Experience Program (OURE)

The popular geostationary orbit has become overcrowded with satellites. To remedy this problem, Tundra Orbit Constellations have been proposed. A Tundra Orbit is a constellation of three or more satellites orbiting in an inclined eccentric orbit. The purpose of this study is to provide an alternative to the geostationary belt and supply continuous coverage for the Northern Hemisphere, in particular the United States. To ensure the most economical configuration of satellites, an analysis of the benefits of number of satellites in such orbits and the change in coverage they provide must be performed. During analysis, it was discovered that comparisons …

Development Of Spring Flow Rating Curve For Ha Ha Tonka Spring, Vanessa L. Eckhoff

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of this project was to develop a rating curve for the Ha Ha Tonka spring, located in Ha Ha Tonka State Park. The rating curve is an empirical relationship between spring discharge and the water level at the stream observation point. An additional goal of the project was to develop an interpretative display to communicate current spring discharge to park visitors. Spring discharge and water level were measured periodically between April 2004 and March 2005. A rating curve was plotted using the collected data. Two possible types of interpretative displays were presented to park visitors. The option preferred …

Extent And Distribution Of Individual Proterozoic Orogenic Belts In Southern Africa From Gravity And Magnetic Data, David Heeszel

Opportunities for Undergraduate Research Experience Program (OURE)

Newly compiled gravity and magnetic datasets, in conjunction with existing geochemical/geochronological data have been able to provide a unique view into the structural evolution of individual Proterozoic mobile belts of southern Africa. Currently there is little actual evidence to support the proposed boundaries for many of the Proterozoic belts that surround the Kaapvaal and Zimbabwe Cratons except for very limited geochemical data and even more limited structural mapping. These newly compiled gravity and magnetic datasets have been able to significantly improve our understanding of the structural geology of these belts and better constrain their evolution and the tectonic interrelationships that …

The Impact Of Octant-Based Relative Color Determination On Features For Skin Lesion Discrimination In Dermoscopy Images, Jorge Lopez

Opportunities for Undergraduate Research Experience Program (OURE)

Skin lesion color is one of the main features analyzed in the diagnosis of malignant melanoma, one of the deadliest forms of cancer. Thus, the relative skin color of a lesion is obtained by applying a simple algorithm for different regions of the skin image. Then, color histogram analysis over a set of images was used in order to compute fuzzy logic-based color descriptors of skin lesions to discriminate malignant melanoma from benign lesions in dermoscopy images.

A Methodology To Assess Critical Infrastructures And Their Relevance To Missouri, Tricia Mattson

Opportunities for Undergraduate Research Experience Program (OURE)

September 11, 2001, a day when thousands oflives were lost under unexpected and unprecedented circumstances, marked the beginning of a difficult national reality; that is, the vulnerability of our society and our infrastructures to terrorist attack. The events of that day have shaken the very foundations of national and the newly coined, "homeland security". It is apparent that changes need to be made to the national/homeland security infrastructure at all levels. But how will change be brought about and what "roadmap" will we follow?

The research team of Dr. Tokuhiro has been studying complex social-technological issues. We are especially interested …

Molybdenum Adsorption On Iron Oxides Lead-Succimer Compounds In Chelation Therapy, Jacob Naeger

Opportunities for Undergraduate Research Experience Program (OURE)

For this research opportunity, two different projects were performed. Much time and effort was put into each project both over the summer of 2004, the winter semester 2004, and spring 2005. Various challenges were present with each experiment. lbese challenges did not prevent learning and research success, however. lbrough the work, much knowledge was discovered despite numerous unfortunate setbacks. This paper chronicles the results from each experiment. In each proceeding section, two subsections indicate discussion and results from each individual experiment.

Engineering Management: Student And Alumni Perspectives, Vaishalee Naruka

Opportunities for Undergraduate Research Experience Program (OURE)

Engineering Management which is considered to be a "non-traditional" field of engineering has a long history of attracting high caliber students regardless of some negative perceptions. This study was done at the University of Missouri - Rolla through focused interviews of forty current students and ten alumni in industry. The objective was to find out what motivated these students to pursue Engineering Management as a discipline, their perceptions and their success in industry compared to "traditional" engineers. This study showed that Engineering Management students just like others, choose a career path that satisfies their needs. These students tended to like …

Cultural Mindset Concerning Water: Ongoing Research In Lemoa, Guatemala, Moya O'Berry

Opportunities for Undergraduate Research Experience Program (OURE)

Attitudes and behaviors regarding water consumption were investigated in two rural indigenous communities in the central highlands of Guatemala. Results indicated that residents of a community at which a deep (245 m) well had been installed were more favorably disposed toward well water. Directions for future research include education for the local residents about their water sources and the link between illness and contaminated water, thereby leading to greater usage of the well. Implications for collaboration between engineering and social science approaches are discussed.

New Technology Does Old Tricks, Ryan Parish

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this project was to create an interactive slide rule accessible over the Internet, usable to illustrate both the principles behind logarithms and how to use a beautiful but obsolete piece of technology. To see this project in action, visit it on the web at http://web.umr.edu/-ouresr/SlideRule/SlideRule.htm.

Study Of The Dynamic Response Of Human Skull Impact On Laminated Automotive Glazing, Sandeep Pedam

Opportunities for Undergraduate Research Experience Program (OURE)

During vehicle accident, occupants head impacting on windshield or side window is commonly observed. It is estimated that over 40,000 people are killed annually in vehicle related accidents in the United States. Use of laminated glass which consists of two soda lime glass plies adhered by a polyvinyl butyryl (PVB) interlayer on automotive windshields and side windows can reduce the possibility of body injury and property damage caused by flying glass fragments. Most of the previous work on laminated glass under head impact has primarily concerned the dynamic response of head rather than the laminated glazing. Any attempt to design …

Determination Of Cadmium And Gold Concentrations Utilizing Neutron Activation Analysis, Bren Phillips

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.

Emc Investigations In Switch Mode Power Supply, Ashwin Shashindranath

Opportunities for Undergraduate Research Experience Program (OURE)

An experimental investigation on the radiated emissions caused by a high current switched mode power supply (SMPS) that supplies a CPU was performed. The emissions testing revealed data that could be used to predict causes of electromagnetic radiation from inside the computer. The noise sources identified included clocks on the motherboard, which was excluded for the purposes of this study. Testing concentrated on the SMPS and some theoretical ideas are proposed for better construction of the power supply.

Geological Research Regarding A Well In Mutare, Zimbabwe, Laura Ruf

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this project was to collect information regarding the geology and hydrogeology of the area surrounding Mutare, as well as any other information that would be needed for determining a water supply for a well that will be built there. Unfortunately, much of this information could not be found. The two water sources that seem to be the most easily provided are building a well on spot or extending pipes to the Pungwe project. Determining which is the better choice would require a geologist or geological engineer to survey the site planned for the orphanage.

Opportunities For Undergraduate Research Experiences (Oure) Research Papers 2004-2005 Volume Iii, Sandeep Pedam, Bren Phillps, Eric Pieper, Andrew Ricke, Laura Ruf, Kristin L. Russell, Tessa C. Russell, Alfred L. Schovanez Iii, Ashwin Shashindranath, Jeanne Shipman, Jeremy Snyder, Christopher Speer, Reid Stephens Jr., Abbie Stewart, Wesley Trueblood, Kendra Waltermire, Daniel Wheaton, Patrick Williams, Charles Williams, Tanner Womack, Ming-Fung Wong, Chris Wright, Bonnie Yates, Elizabeth Zuchek

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.

The Role Of Regulatory And Liability Issues Stemming From The Mit Report, Tlte Future Of Nuclear Power, Christopher Speer

Opportunities for Undergraduate Research Experience Program (OURE)

With the nation's need for electricity and want for a cleaner environment increasing, nuclear energy seems to be an effective resource for meeting both those needs. MIT has recently released a paper entitled "The Future of Nuclear Energy" in which they propose the feasibility a large growth of the nuclear industry. However, their growth scenario fails to take into account several regulatory and liability issues that would arise with a large growth in the nuclear industry. Those issues must be understood before the nuclear industry can begin to grow. In this report, we attempt to clarify those issues.

Tether Reel Mechanism For The Mr Sat Project, Abbie Stewart

Opportunities for Undergraduate Research Experience Program (OURE)

The Missouri-Rolla Satellite (MR SAT) system is being designed and constructed by students at the University of Missouri - Rolla in order to give Aerospace Engineering students along with other major's practical experience in spaceflight concepts. The satellite system will consist of two tethered satellites that will eventually be completely disconnected and use a propulsion method to enter the chase phase of our mission. New design concepts are being used on this satellite including the possible use of a honeycomb-aluminum friction stir-welded structure and micro-pulse plasma thrusters for maneuvering. The research done this summer focused on the tether reel mechanism …

Adhesion Of An Axisymmetric Film Onto A Rigid Substrate: Application To A Mem-Rf-Switch, Ming-Fung Wong

Opportunities for Undergraduate Research Experience Program (OURE)

A solid mechanics model is constructed to discuss the mechanical aspect of a MEM-RF-switch. A thin circular membrane clamped at the perimeter is adhered to a rigid cylindrical flat punch. A tensile load applied to the punch causes an interfacial de lamination. Once the contact circle shrinks to 0.1758 - 0.3651 of the punch dimension depending on the magnitude of the tensile residual stress on the film, a spontaneous delamination, or "pull-off', occurs and the film snaps from the substrate at a critical load and punch displacement. The theoretical model has significant implications in MEMS that involves active moveable films.

Opportunities For Undergraduate Research Experiences (Oure) Research Papers 2004-2005 Volume I, Trevor J. Acorn, Kyle R. Anderson, Tim Assel, Andrew Baughman, Chad Beardslee, Kyle Benne, C. M. Bollinger, Amy L. Bone, Jerrod Bourchard, Amy Boulch, Bronson Bowling, Christina Bradstreet, Nathan Branham, Buchholz Brown Jr., Brandow Bundy, John Wesley Cable, Adam Chadek, M. F. Chandler, Christopher Claussen, Peter Cross, Ryan Davidson

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.