Browsing by Subject "Complexity"
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Item Deciding among models : a decision-theoretic view of model complexity(2010-05) Mozano, Jennifer Maile; Bickel, J. Eric; Lake, Larry W.This research examines the trade-off between the cost of adding complexity to a model and the value added to the results within the context of decision-making. It seeks to determine how complex a model should be in order to fit it to the purpose at hand. The report begins with a discussion on general modeling theory and model complexity. It next considers the specific case of petroleum reservoir models and the existing research that has compared modeling results with model complexity levels. Finally, it presents original results applying Monte Carlo sampling to a drilling decision scenario and to a one-dimensional reservoir model where a cylindrical oil field is represented by different numbers of cells and the results compared.Item Language applications for UEFI BIOS(2014-05) Leara, William Daniel; Aziz, AdnanThe Unified Extensible Firmware Interface (UEFI) is the industry-standard Basic Input/Output System (BIOS) firmware specification used by modern desktop, portable, and server computers, and is increasingly being ported to today's new mobile form factors as well. UEFI is firmware responsible for bootstrapping the hardware, turning control over to an operating system loader, and then providing runtime services to the operating system. ANTLR (ANother Tool for Language Recognition) is a lexer-parser generator for reading, processing, executing, and translating structured text and binary files. It supersedes older technologies such as lex/yacc or flex/bison and is widely used to build languages and programming tools. ANTLR accepts a provided grammar and generates a parser that can build and walk parse trees. This report studies UEFI BIOS and compiler theory and demonstrates ways compiler theory can be leveraged to solve problems in the UEFI BIOS domain. Specifically, this report uses ANTLR to implement two language applications aimed at furthering the development of UEFI BIOS implementations. They are: 1. A software complexity analysis application for UEFI created that leverages ANTLR's standard general-purpose C language grammar. The complexity analysis application uses general-purpose and domain-specific measures to give a complexity score to UEFI BIOS modules. 2. An ANTLR grammar created for the VFR domain-specific language, and a sample application which puts the grammar to use. VFR is a language describing visual elements on a display; the sample application creates an HTML preview of VFR code without requiring a developer to build and flash a BIOS image on a target machine to see its graphical layout.Item Leadership for resilient urban systems : two cases in Asheville, NC(2016-08) Bush, Alan Christen; Wilson, Patricia Ann; Wenhong, Chen; Wegmann, Jake; Holleran, MichaelThe role of leadership in the resilience of urban systems is poorly understood. Leadership can be thought of as a complex practice, where the functions of leadership emerge from the relationships amongst actors, systems and institutions. There are five theorized functions of Complexity Leadership: Community Building, Information Gathering, Information Using, Generative and Administrative. The purpose of this dissertation was to explore the connection, if any, between Complexity Leadership and the resilience of urban systems. This was explored in the context of two cases in Asheville, NC: the Residents' Council of Public Housing of Asheville and Rainbow Community School. The Residents' Council is a non profit that represents residents’ interests; Public Housing in Asheville is a typical for a 100k small city. The case documents some of the Residents' Council's attempt to adopt Dynamic Governance, a set of self-organizing governance practices. Rainbow Community School is a private k-8 school, recognized internationally as an Ashoka Change-Maker School for its innovative model of education. Data was collected through a hybrid of traditional ethnographic techniques and distributed ethnography. Data was analyzed inductively, using a combination of qualitative analysis and set theoretic analysis. The research generated findings of three kinds. First, complexity leadership was necessary but not sufficient to account for the observed resilience qualities. To explain the observed coordination across other functions and capacity to engage with mystery , this research theorizes an additional function of Complexity Leadership—a Spiritual function. Second, individual strategic leadership played a role in fostering resilience through strengthening weak functions of complexity leadership. Third, resilience qualities emerged over time through the process of Panarchy. Spiritual leadership plays a role in fostering Panarchy through creating conditions for cross-scale resonance. The dissertation closes with the contributions of this research to theory, practice, and methods for research in complex urban systems.Item Multi-frac propagation in unconventional shale(2015-12) Asiamah, Nana Kwadwo Sasu; Olson, Jon E.; Schultz, RichardIn recent years, the Zipper-Frac technique has become one of the most widely used stimulation techniques in the oil and gas industry. The efficiency in this technique lies in minimizing stress shadows between adjacent stimulated fractures while maximizing fracture network and surface area in order to increase fluid production. The Zipper-Frac technique stimulates two parallel horizontally drilled wellbores, alternating between perforation clusters, while maintaining pressure in the previously fractured wellbore or perforation cluster. This study analyzes and discusses multi-fracture experiments in the laboratory that mimic Zipper-Frac results in unconventional shale. The experiments were conducted with two intended outcomes: (i) to examine how time-dependent pressure decay limits stress shadow effects and (ii) to investigate fracture complexity developed in Zipper-Fracs. To achieve these objectives, laboratory experiments were conducted on synthetic blocks (gypsum cement) of three layers (hydrostone, plaster and hydrostone, respectively). The experiment was conducted on 12 samples. Six samples were fractured with a pressure hold-up technique, where the in-situ stress after fracturing was above the fracture closure stress (FCS); and the other six were fractured with a pressure bleed-off technique, where the pressure was bled-off below the FCS. The results indicate is that greater well spacing and bleeding off pressure in fractures post-treatment result in longer and straighter fractures, hence minimal stress shadow, while closer well spacing and maintaining pressure in fractures post-treatment caused more non-planar fracture paths and less created fracture length, hence stronger stress shadow. Consequently, it can be inferred that less complexity would result with the bleed-off method, but this gives greater fracture surface area because of the greater achieved lengths.Item The Norwegian success story : narrative applications of interpretation, understanding, & communication in complex organizational systems(2013-12) Goins, Elizabeth Simpson; Browning, Larry D.Stories about the oil and gas industry are made for drama; these are tales of unimaginable wealth, unimaginable power, and oftentimes, unimaginable deeds. But what should we make of an oil and gas narrative without a blood feud or villain? This is the story of the Norway Model, a unique system of natural resource management responsible for this country’s transformation since 1969 when massive oil reserves were discovered on the North Sea continental shelf. After centuries of foreign occupation, the Norwegian government has built a thriving petroleum sector to fund its social welfare system beyond even the highest expectations; somehow, this nation of five million people grew from a poor maritime society to a global leader in environmentally conscious energy production with the largest sovereign wealth fund in the world. Despite these results, this oil economy faces new challenges in the coming years; as North Sea production declines, Norway increasingly looks north for fossil fuels in the Arctic and how these resources are discovered, produced, and regulated will require new innovations to ensure the sustainability of this welfare state. Thus, the next chapter of the Norwegian success story remains to be written and this dissertation explores how narratives about the past, present, and future of the Norway Model will shape the course of natural resource management policies. In presenting the case of Norway’s success from a narrative perspective, this research breaks new ground in both applied and theoretical territories. As perhaps the most successful system of its kind in the world, scholars and policy makers alike have much to learn from studying this model. But when it comes to understanding the dynamic connections between energy management, international policy, and global warming, positivistic models for prediction and causality have fallen short (Smil, 2005). In contrast, narrative can communicate nuanced meanings in complex systems of organization. Therefore, this research explores the connections between narrative and complexity, as well as the communicative applications of narrative for understanding and organizational decision-making. Overall, conceptualizing this model’s evolution as a narrative offers tangible entry points for understanding how one country’s story can change the world.Item Relating energy use to economic complexity(2015-05) Bond, Stephen Richard; King, Carey Wayne, 1974-Energy is a fundamental requirement for the development of any complex human system. One prevalent view suggests that societal development is a direct result of increased energy use, such that progress occurs mainly during times when a surplus of energy is available. Alternately, anthropologist Joseph Tainter posits that human systems increase in complexity as a means of solving social problems, which requires additional energy use. Tainter's theory, since it implies compulsory increases in resource use, has significant implications for long-term economic sustainability. This thesis is an attempt to provide support, or show a lack thereof, for Tainter's theory. To accomplish this, the concept of entropy, in the context of information theory, is used as an indicator of economic complexity. Economic input-output tables for 40 countries from the World Input Output Database are used to calculate these metrics, on an annual basis between 1995 and 2011. Several model boundaries, on both the global and country scales, are used to select the data for these calculations. The results are compared to energy consumption and production data from the U.S. Energy Information Administration. This thesis presents the results of this comparison in the context of quantifying Tainter's theory of the linkage between energy and complexity.