Barrier-controlled carrier transport in microcrystalline semiconducting materials: Description within a unified model

A recently developed model that unifies the ballistic and diffusive transport mechanisms is applied in a theoretical study of carrier transport across potential barriers at grain boundaries in microcrystalline semiconducting materials. In the unified model, the conductance depends on the detailed structure of the band edge profile and in a nonlinear way on the carrier mean free path. Equilibrium band edge profiles are calculated within the trapping model for samples made up of a linear chain of identical grains. Quantum corrections allowing for tunneling are included in the calculation of electron mobilities. The dependence of the mobilities on carrier mean free path, grain length, number of grains, and temperature is examined, and appreciable departures from the results of the thermionic-field-emission model are found. Specifically, the unified model is applied in an analysis of Hall mobility data for n-type microcrystalline Si thin films in the range of thermally activated transport. Owing mainly to the effect of tunneling, potential barrier heights derived from the data are substantially larger than the activation energies of the Hall mobilities. The specific features of the unified model, however, cannot be resolved within the rather large uncertainties of the analysis.Comment: REVTex, 19 pages, 9 figures; to appear in J. Appl. Phy

The role of fault zones on structure, operation and prospects of geothermal reservoirs - A case study in Lahendong, Indonesia

Der weltweit steigende Energiebedarf stellt die Menschheit vor immer größere Herausforderungen. Im Angesicht des Klimawandels und der begrenzten Verfügbarkeit von fossilen Energieträgern liegt eine besondere Verantwortung bei der Entwicklung von erneuerbaren Energieressourcen. Dabei spielt die Geothermie eine besondere Rolle, da sie zur Deckung der Grundlast geeignet ist. Zu der Bewertung von geothermischen Potentialen leisten die Geowissenschaften einen großen Beitrag. Das geothermische Potential eines Standorts hängt vor allem von der Art und Ausbreitung von Störungszonen ab, da sie wesentlich den Grundwasserfluss kontrollieren. In dieser Arbeit werden verschiedene geowissenschaftliche Methoden miteinander kombiniert, um die Wirksamkeit von Störungszonen zu bewerten. Strukturgeologische Kartierungen und hydrogeologische Felduntersuchungen erklären die Ausbreitung und hydraulische Funktion von Störungszonen im Untersuchungsgebiet. Geohydrochemische Untersuchungen geben Auskunft über Fluid- und Gesteinszusammensetzung und deren Wechselwirkungen. Numerische Simulationen des Gebietes zeigen, dass sowohl Störungszonen als auch Fluideigenschaften wichtig für die Verteilung von Druck und Temperatur im Reservoir sind. Das Untersuchungsgebiet ist das Hochenthalpy-Geothermiefeld Lahendong in Sulawesi (Indonesien). Ein Kraftwerk produziert hier 80 MW Elektrizität. Die ersten Untersuchungen im Gebiet starteten in den 1970er Jahren. Jedoch sind Genese und Verteilung der thermalen Wässer noch nicht komplett verstanden. Das aktuelle konzeptionelle Modell zeigt eine Aufteilung in mehrere Reservoirbereiche. Die verschiedenen Bereiche sind durch horizontal impermeable Störungszonen voneinander getrennt. Den nördlichen Bereich kennzeichnen saure Wässer und den südlichen Teil pH-neutrale Wässer. Auch die Produktivität variiert stark zwischen den beiden Reservoirbereichen. In vertikaler Richtung sind Störungszonen jedoch durchlässig, was dazu führt, dass heiße Quellen entlang von Störungen oder deren Kreuzungspunkten auftreten. Die Reservoirgesteine in Lahendong sind basaltische Andesite, Tuffe und vulkanische Brekkzien. Die Permeabilitätsverteilung der Störungszonen wird durch die Ausbreitung von Rissen kontrolliert. Risse sind vor allem in der Bruchzone der Störung verbreitet, was zu einer hydraulischen Durchlässigkeit parallel zur Störung führt. Die Unterteilung des Reservoirs in Lahendong wird durch diese Rissverteilung bestimmt. Der nördliche saure Teil des Reservoirs ist durch höhere Produktivitätsraten, Gasaustritte an der Oberfläche und stark alterierte und geklüftete Gesteine im Untergrund charakterisiert. Der südliche Abschnitt ist heißer und hat weniger stark alterierte Gesteine. Die beobachteten Reservoireigenschaften wurden von hydrochemischen und hydraulischen Modellierungen bestätigt. Der Grundwasserfluss mit Neubildung und Austritten aus dem Reservoir ist im Gelände und im Modell vor allem durch Störungszonen kontrolliert. Jedoch ist der Grundwasserfluss auch durch den Aggregatzustand des Wassers beeinflusst. Für die Modellierung von 2-Phasen-Ausbreitung müssen die Permeabilitäten angepasst werden, um gleiche Temperatur- und Druckbedingungen zu modellieren. Der Hauptbeitrag dieser Arbeit liegt in der Demonstration, dass eine systematische strukturgeologische Analyse für das Verständnis von Grundwasserfluss in geothermischen Reservoiren unentbehrlich ist. Es wurde bestätigt, dass die Kombination von tektonischen, hydrogeologischen und geohydrochemischen Informationen den wichtigsten Beitrag für das Verständnis von Grundwasserströmungen leistet. Die Grundwasserströmung ist der wichtigste Faktor für die Wahl des richtigen Standortes für Produktion und Injektion in geothermischen Feldern. Eine detaillierte Analyse gewährleistet eine nachhaltige Nutzung des Feldes und verringert Risiken, wie schwach produzierende Bohrungen oder die Produktion von stark korrosiven Wässern. Auf dieser Grundlage kann eine Felderweiterung geplant werden, wie es in Lahendong angedacht ist

Sports Animations

Project Title: Sports Animations Name: Brehme Smiler Quidzinski Major: Digital Arts & Culture Minor (if applicable): Film Studies Expected Graduation: December 2020 Project Medium: Computer generated animations and videos Technology and Software Used: Adobe After Effects/Premier Artist Statement: Last summer I was able to land a job as an intern working with the soccer team Green Bay Voyageurs, this team shares a stadium with a baseball team called the Green Bay Booyah and working for the Voyageur lead to opportunities to work with both teams. This summer I am again working for both teams, knowing that I was going to work for these teams again I decided that my project for DAC 661 would be creating animations and other small media projects for these teams. The animations were decided based on each respected sport and ideas given to me by the teams, though not all will be finished or deemed right for this submission. For the baseball team I created animation for when a batter strikes out, a home run is hit, and for if the team wins. For the soccer team I went with when the team scores and when they win as their videoboard usage is limited more so than the baseball team. I also was asked to try and make some animations or videos for in-between game breaks that fans could interact with, a shuffle game where fans follow an item was one of the ideas selected. Going into the project, I had little idea on how to use Adobe After Effects or how people even made these animations. I started by looking up tutorials on YouTube for simple animation and then tried to put a spin on them or combine them to improve the animations. I would start with the backgrounds and then add text, color, and images that work with the animations before putting them together and finalizing them. I would make the animations in After Effects then add an touch-ups or variations in Adobe Premier, most animations last around seven seconds and are made to repeat forever (or until we need the animations to run). These animations may last for about a minute or less during games, in baseball games there is about thirty seconds between when a batter strikes out and the next batter coming up meaning these animations most be quick and noticeable (or at least flashy). Being this is my first attempts at animations, and I have enjoyed learning After Effects and working with the teams. While these animations are important, my main job with the teams is streaming games for both teams. With the shortened season due to Covid-19, I plan to get as much work done with the teams no matter what type of work it is. Whether this leads to more animation or not, I hope that working on these animations will leave me with plenty of experience for other jobs or projects going forward

Relativistic Generalization and Extension to the Non-Abelian Gauge Theory of Feynman's Proof of the Maxwell Equations

R.P. Feynman showed F.J. Dyson a proof of the Lorentz force law and the homogeneous Maxwell equations, which he obtained starting from Newton's law of motion and the commutation relations between position and velocity for a single nonrelativistic particle. We formulate both a special relativistic and a general relativistic versions of Feynman's derivation. Especially in the general relativistic version we prove that the only possible fields that can consistently act on a quantum mechanical particle are scalar, gauge and gravitational fields. We also extend Feynman's scheme to the case of non-Abelian gauge theory in the special relativistic context.Comment: 22 page

GIS Analysis of Factors Influencing Particulate Pollution in Keene, New Hampshire

This study aims to identify the characteristics of air inversions and Particulate Matter 2.5 (PM2.5) in the city of Keene, New Hampshire. PM2.5 is a type of particulate pollutant with a diameter of less than 2.5 microns that exists naturally, and can be created through industrial processed and the combustion of biomass. The combustion of wood as a home heating fuel is considered the main source of PM2.5 in Keene. Meteorological factors were investigated by searching through quality assured meteorological record provided by the New Hampshire Department of Environmental Services. Wintertime temperature inversions are of particular concern as they trap pollutants near the ground, creating high concentrations of PM2.5. This is particularly true for Keene, which is in a glacial valley. This study concluded that air inversions and high PM2.5 event are most likely to occur on cold, clear, windless nights during the winter. The temperature must drop at least 11 degrees Fahrenheit, with a dew point close to the ambient temperature. The other objective of the study was to create a model that would predict the areas that will experience high PM2.5 concentrations as the result of demographic and topographical factors. The model was built using Digital Elevation Models, and building footprints provided by the University of New Hampshire Database. Housing density was calculated using the building footprints layer, and combined with areas that have less than three degrees of slope. This was compared to mobile monitoring data collected during the timeframe of the study.Faculty Sponsor: Dr. Chris Brehm

Combined population dynamics and entropy modelling supports patient stratification in chronic myeloid leukemia

Modelling the parameters of multistep carcinogenesis is key for a better understanding of cancer progression, biomarker identification and the design of individualized therapies. Using chronic myeloid leukemia (CML) as a paradigm for hierarchical disease evolution we show that combined population dynamic modelling and CML patient biopsy genomic analysis enables patient stratification at unprecedented resolution. Linking CD34+ similarity as a disease progression marker to patientderived gene expression entropy separated established CML progression stages and uncovered additional heterogeneity within disease stages. Importantly, our patient data informed model enables quantitative approximation of individual patients’ disease history within chronic phase (CP) and significantly separates “early” from “late” CP. Our findings provide a novel rationale for personalized and genome-informed disease progression risk assessment that is independent and complementary to conventional measures of CML disease burden and prognosis

Injection related issues of a doublet system in a sandstone aquifer - A generalized concept to understand and avoid problem sources in geothermal systems

This study proposes a concept and presents a workflow to examine potential reasons for low injectivity of sandstone aquifers. Injection related problems are a major challenge for the sustainable utilization of geothermal waters. In order to completely understand and avoid the geothermal reinjection problems, potential problem sources acting on different scales should be taken into consideration. Thus, in the workflow, possible problem sources are considered on regional, reservoir and local scale and categorized into 1) effect of regional hydraulics (potential presence of overpressure and upward flow) 2) inadequate reservoir performance (limited extent, low permeability and performance) and 3) local clogging processes (particle migration, mineral precipitation, microbial activity). Hydraulic conditions are characterized by defining the pressure regime and the direction of vertical driving forces. The reservoir properties are given by determining the grain size and the size of the reservoir layers, as well as the permeability and the transmissivity of the reservoir and the capacity of the injector. Physical, chemical, and biological clogging processes are investigated by specifying the rock properties and determining particle content of the fluid; by analysing the type, probability and amount of the scaling and estimating the potential for corrosion; and by evaluating the possibility of biofilm formation. The concept and the workflow were first tested on a geothermal site (Mezőberény, SE Hungary, installed in 2012) that had to stop operation because of unsuccessful reinjection. The low injectivity of the well is a consequence of several separate problems and their interaction: Reservoir properties are insufficient due to low permeability and transmissivity of the reservoir and the limited vertical and horizontal extension of the sandstone bodies. Precipitation of carbonates, iron and manganese minerals is predicted in hydrogeochemical models and observed in solid phase analysis. Microbial material is produced from the particularly high organic content of the produced thermal water. Injection problems due to hydraulic effects are not expected since the regional pressure regime is slightly subhydrostatic. In summary, reservoir properties determine a low injectivity, which is further decreased to a critical level by the clogging processes. The proposed generalized concept guides a detailed reservoir and geothermal system analysis which is essential for a sustainable geothermal operation.Petroleum Engineerin

GIS Analysis of Factors Influencing Particulate Pollution in Keene, New Hampshire

This study aims to identify the characteristics of air inversions and Particulate Matter 2.5 (PM2.5) in the city of Keene, New Hampshire. PM2.5 is a type of particulate pollutant with a diameter of less than 2.5 microns that exists naturally, and can be created through industrial processed and the combustion of biomass. The combustion of wood as a home heating fuel is considered the main source of PM2.5 in Keene. Meteorological factors were investigated by searching through quality assured meteorological record provided by the New Hampshire Department of Environmental Services. Wintertime temperature inversions are of particular concern as they trap pollutants near the ground, creating high concentrations of PM2.5.This is particularly true for Keene, which is in a glacial valley. This study concluded that air inversions and high PM2.5 event are most likely to occur on cold, clear, windless nights during the winter. The temperature must drop at least 11 degrees Fahrenheit, with a dew point close to the ambient temperature. The other objective of the study was to create a model that would predict the areas that will experience high PM2.5 concentrations as the result of demographic and topographical factors. The model was built using Digital Elevation Models, and building footprints provided by the University of New Hampshire Database. Housing density was calculated using the building footprints layer, and combined with areas that have less than three degrees of slope. This was compared to mobile monitoring data collected during the timeframe of the study