Dynamical van der Waals atom -surface interaction

We obtained new nonrelativistic expression for the dynamical van der Waals atom -surface interaction energy of very convenient form for different applications. It is shown that classical result (Ferrell and Ritchie, 1980) holds only for a very slowly moving atom. In general case, the van der Waals atom -surface interaction energy manifests strong nonlinear dependence on velocity and distance. In close vicinity of metal and dielectric surfaces and velocities from 1 to 10 Bohr units the dynamical van der Waals potential proves to be significantly lower that in static case and goes to the static values with increasing distance and (or) decreasing velocity.Comment: 15 pages,4 figures; corrected abstract,numerical calculations and conclusion

What You See is What You Get

This thesis statement describes and comments on the four videos that compose my thesis exhibition, What you See is What You Get. Together, they constitute a self-portrait. Videos require multiple mediums and software, each with their own purpose and aesthetic. The three key ingredients these four videos make use of are recorded performances, 2D animation and narrative. This statement will detail the visuals and purpose of each one, the technology and editing process, and the inspirations that have led to the thesis exhibition. The statement describes the choice of color, movement and rhythm to carry the narrative, which is not based chronologically but emotionally. Finally, some attention is given to the tone of the videos and the progression between my past and present self. The overall theme of these videos is self-exploration. A large part of who I am today comes from my early love of cartoons and video games; from consumer I have become creator. I have learned to apply my skills with AfterEffects, Photoshop, GIMP, Game Maker and iMovie to create content that is revealing of my progress through life

Comparative Analysis of Biosurveillance Methodologies

The purpose of this research is to compare two different biosurveillance methodologies: BioWatch and A Hot Idea . BioWatch is fielded and operating in major US cities today. Air samples are collected on filter paper and analyzed for the presence of harmful biological agents. A Hot Idea is an evolving methodology using the human body\u27s immune response to identify the onset of infection from a harmful pathogen. Detecting a temperature increase, using infrared thermographers, in a statistically significant portion of population would allow earlier identification of a biological release, accelerating initiation of response actions. A selected population including policemen, firemen, and postal carriers, will be monitored for elevations in temperature above previously developed individual temperature profiles. The benefit of surveillance can be quantified economically by determining the costs averted by having surveillance in place minus the costs incurred to provide surveillance. Using a model to determine the relationship between initiation of response actions and magnitude of mortality, each surveillance methodology\u27s benefit was quantified based on expected detection time

The Effect of Fluorine on Low Temperature Boron Activation in Ultra Shallow Junctions

As CMOS device dimensions continue to shrink below 200nm, one of the major limiting factors in scaling size will become the drain and source junction depth. Using fluorine to create shallower p type junctions during ion implant is one way to decrease the junction depth. The effect of fluorine on the implant and subsequent anneal processes was studied. A low temperature annealing process was developed to decrease junction depths although sufficient dopant activation is being studied

MINIMIZING STAR TRACKER OCCULTATIONS FOR NASA’S LUNAR RECONNAISSANCE ORBITER IN SUN-SAFE MODE

Due to degradation of the NASA’s Lunar Reconnaissance Orbiter’s (LRO) Inertial Measurement Unit, the LRO relies solely on its star trackers to maintain gyroless attitude control. In the event of an anomaly, the LRO is placed in sun-safe mode in order to reestablish normal operation, which constrains its attitude. While in sun-safe mode, the LRO’s star trackers experience occultations from local orbiting bodies and cannot maintain an attitude solution during these periods. This poses the risk of total loss of the spacecraft due to tumbling or depleted power supply. This thesis provides mission operators with a software-based tool for determining alternate sun-safe attitudes that reduce the occultation time, minimizing operational risk. Ephemeris data from orbiting bodies and the LRO are utilized to investigate occultation occurrences. Periods of star tracker occultations for any given time frame are determined based on the LRO’s fixed attitude. The goal of this thesis is to iterate alternate attitudes to define the ideal attitude that minimizes occultation occurrences. Additionally, data analysis is conducted to determine the ideal attitude update frequency for sun-safe mode based on operational constraints. The design of this software-based tool yields appropriate results for acquiring an ideal attitude solution for minimizing star tracker occultations, giving mission operators the freedom to choose attitude constraints, simulation fidelity, and attitude update frequency.Lieutenant, United States NavyApproved for public release. Distribution is unlimited

Adsorption of ammonia at GaN(0001) surface in the mixed ammonia/hydrogen ambient - a summary of ab initio data

Adsorption of ammonia at NH3/NH2/H covered GaN(0001) surface was analyzed using results of ab initio calculations. The whole configuration space of partially NH3/NH2/H covered GaN(0001) surface was divided into zones differently pinned Fermi level: at Ga broken bond state for dominantly bare surface (region I), at VBM for NH2 and H covered (region II), and at CBM for NH3 covered surface (region III). The extensive ab intio calculations show validity of electron counting rule (ECR) for all mixed coverage, for bordering these three regions. The adsorption was analyzed using newly identified dependence of the adsorption energy on the charge transfer at the surface. For region I and II ammonia adsorb dissociatively, disintegrating into H adatom and HN2 radical for large fraction of vacant sites while for high coverage the ammonia adsorption is molecular. The dissociative adsorption energy strongly depends on the Fermi level at the surface (pinned) and in the bulk (unpinned) while the molecular adsorption energy is determined by bonding to surface only, in accordance to the recently published theory. The molecular adsorption is determined by the energy of covalent bonding to the surface. Ammonia adsorption in region III (Fermi level pinned at CBM) leads to unstable configuration both molecular and dissociative which is explained by the fact that Ga-broken bond sites are doubly occupied by electrons. The adsorbing ammonia brings 8 electrons to the surface, necessitating transfer of the electrons from Ga-broken bond state to Fermi level, energetically costly process. Adsorption of ammonia at H-covered site leads to creation of NH2 radical at the surface and escape of H2 molecule. The process energy is close to 0.12 eV, thus not large, but the inverse process is not possible due to escape of the hydrogen molecule.Comment: 37 pages, 14 figure