You limited your search to:

  Partner: UNT Libraries
 Collection: UNT Theses and Dissertations
Energy-Aware Time Synchronization in Wireless Sensor Networks

Energy-Aware Time Synchronization in Wireless Sensor Networks

Date: December 2006
Creator: Saravanos, Yanos
Description: I present a time synchronization algorithm for wireless sensor networks that aims to conserve sensor battery power. The proposed method creates a hierarchical tree by flooding the sensor network from a designated source point. It then uses a hybrid algorithm derived from the timing-sync protocol for sensor networks (TSPN) and the reference broadcast synchronization method (RBS) to periodically synchronize sensor clocks by minimizing energy consumption. In multi-hop ad-hoc networks, a depleted sensor will drop information from all other sensors that route data through it, decreasing the physical area being monitored by the network. The proposed method uses several techniques and thresholds to maintain network connectivity. A new root sensor is chosen when the current one's battery power decreases to a designated value. I implement this new synchronization technique using Matlab and show that it can provide significant power savings over both TPSN and RBS.
Contributing Partner: UNT Libraries
Energy Distribution of Sputtered Neutral Atoms from a Multilayer Target

Energy Distribution of Sputtered Neutral Atoms from a Multilayer Target

Date: August 2000
Creator: Bigelow, Alan W.
Description: Energy distribution measurements of sputtered neutral particles contribute to the general knowledge of sputtering, a common technique for surface analysis. In this work emphasis was placed on the measurement of energy distribution of sputtered neutral atoms from different depths. The liquid Ga-In eutectic alloy as a sample target for this study was ideal due to an extreme concentration ratio gradient between the top two monolayers. In pursuing this study, the method of sputter-initiated resonance ionization spectroscopy (SIRIS) was utilized. SIRIS employs a pulsed ion beam to initiate sputtering and tunable dye lasers for resonance ionization. Observation of the energy distribution was achieved with a position-sensitive detector. The principle behind the detector's energy resolution is time of flight (TOF) spectroscopy. For this specific detector, programmed time intervals between the sputtering pulse at the target and the ionizing laser pulse provided information leading to the energy distribution of the secondary neutral particles. This experiment contributes data for energy distributions of sputtered neutral particles to the experimental database, required by theoretical models and computer simulations for the sputtering phenomenon.
Contributing Partner: UNT Libraries
Energy Harvesting Wireless Piezoelectric Resonant Force Sensor

Energy Harvesting Wireless Piezoelectric Resonant Force Sensor

Date: December 2013
Creator: Ahmadi, Mehdi
Description: The piezoelectric energy harvester has become a new powering option for some low-power electronic devices such as MEMS (Micro Electrical Mechanical System) sensors. Piezoelectric materials can collect the ambient vibrations energy and convert it to electrical energy. This thesis is intended to demonstrate the behavior of a piezoelectric energy harvester system at elevated temperature from room temperature up to 82°C, and compares the system’s performance using different piezoelectric materials. The systems are structured with a Lead Magnesium Niobate-Lead Titanate (PMN-PT) single crystal patch bonded to an aluminum cantilever beam, Lead Indium Niobate-Lead Magnesium Niobate-Lead Titanate (PIN-PMN-PT) single crystal patch bonded to an aluminum cantilever beam and a bimorph cantilever beam which is made of Lead Zirconate Titanate (PZT). The results of this experimental study show the effects of the temperature on the operation frequency and output power of the piezoelectric energy harvesting system. The harvested electrical energy has been stored in storage circuits including a battery. Then, the stored energy has been used to power up the other part of the system, a wireless resonator force sensor, which uses frequency conversion techniques to convert the sensor’s ultrasonic signal to a microwave signal in order to transmit the signal wirelessly.
Contributing Partner: UNT Libraries
Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Date: August 1961
Creator: Kregel, Mark Douglas
Description: The purpose of this thesis is to study energy losses suffered by protons in traversing a plasma through collision with the electrons of the plasma. For these electrons a variety of non-Maxwellian velocity distributions are assumed.
Contributing Partner: UNT Libraries
Energy Paths and Political Commitments: Their Roles in Environmental Inequality

Energy Paths and Political Commitments: Their Roles in Environmental Inequality

Date: May 2014
Creator: Ong, Corinne
Description: Decentralized renewable energy procurement has gained traction in recent years for its potential to alleviate rural energy poverty and environmental degradation in developing countries. Hence, this study investigates if deploying renewable energy can mitigate rural energy poverty in developing countries as often claimed. Because any energy regime cannot be initiated or sustained without the conviction of local political leaders, the study also evaluates the extent to which government investments in the development of renewable energy technologies and the energy sector, affect the environmental quality (i.e. greenhouse gas emissions) of developing countries. Energetic theory and environmental inequality constitute the key conceptual premises guiding this study. Ordinary least squares regression is utilized to analyze the relationship between key variables. The results reveal that as of 2010, use of renewable energy can indeed support rural electrification. Higher GNI per capita and use of conventional fuels are also positively related to rural electrification, all else equal. As for environmental degradation in 2005 and 2008, R&D investments actually tend to increase GHG emissions; procuring energy from either renewable or non-renewable sources is however, found to be environmentally detrimental, net of all other variables. Finally, some evidence is found for the role of aid funds and ...
Contributing Partner: UNT Libraries
Energy Policy in the Republic of China and Japan, 1970-1985: A Comparative Examination of Energy Politics and Policies

Energy Policy in the Republic of China and Japan, 1970-1985: A Comparative Examination of Energy Politics and Policies

Date: August 1987
Creator: Wang, Han-Kuo
Description: The impact of the energy crises in the 1970s hit all oil-importing countries much harder than it hit countries endowed with domestic supplies of energy. Energy politics and policies for the oil-importing countries have become vital issues that need to be examined. The purpose of this dissertation is to examine and compare the energy politics and policy processes in the Republic of China (ROC) and Japan during the period of 1970-1985. The study focuses on the politics of energy policies, using a policy analysis or systems framework for examining the policy processes in the two countries. A comparison is made of energy environments, the political actors, the institutions, and finally the substance of energy policy. An assessment is then made of the effects or consequences of energy policies on these two countries. In attempting to study energy politics and policies in these two Asian countries, the researcher began with a policy model or conceptual schema of energy politics from which the researcher raised a number of research questions. These questions were used to guide the direction of the study. A comparison was first made of energy systems, and then the major actors in the energy resources field were identified by ...
Contributing Partner: UNT Libraries
Energy Usage While Maintaining Thermal Comfort : A Case Study of a UNT Dormitory

Energy Usage While Maintaining Thermal Comfort : A Case Study of a UNT Dormitory

Date: December 2011
Creator: Gambrell, Dusten
Description: Campus dormitories for the University of North Texas house over 5500 students per year; each one of them requires certain comfortable living conditions while they live there. There is an inherit amount of money required in order to achieve minimal comfort levels; the cost is mostly natural gas for water and room heating and electricity for cooling, lighting and peripherals. The US Department of Energy has developed several programs to aid in performing energy simulations to help those interested design more cost effective building designs. Energy-10 is such a program that allows users to conduct whole house evaluations by reviewing and altering a few parameters such as building materials, solar heating, energy efficient windows etc. The idea of this project was to recreate a campus dormitory and try to emulate existent energy consumption then try to find ways of lowering that usage while maintaining a high level of personal comfort.
Contributing Partner: UNT Libraries
Engaging Lives: a Nomadic Inquiry Into the Spatial Assemblages and Ethico-aesthetic Practices of Three Makers

Engaging Lives: a Nomadic Inquiry Into the Spatial Assemblages and Ethico-aesthetic Practices of Three Makers

Date: May 2014
Creator: Coats, Cala R.
Description: This research is a nomadic inquiry into the ethics and aesthetics of three makers’ social and material practices. Deleuze’s concept of the nomad operated in multiple ways throughout the process, which was embedded in performative engagements that produced narratives of becoming. Over four months, I built relationships with three people as I learned about the ethico-aesthetic significance of their daily practices. The process started by interviewing participants in their homes and expanded over time to formal and informal engagements in school, community, and agricultural settings. I used Guattari’s ecosophical approach to consider how subjectivity was produced through spatial assemblages by spending time with participants, discussing material structures and objects, listening to personal histories, and collaboratively developing ideas. Participants included a builder who repurposed a missile base into a private residence and community gathering space, an elementary art teacher who practiced urban homesteading, and a young artist who developed an educational farm. The research considers the affective force of normalized social values, the production of desire by designer capitalism, and the mutation of life from neoliberal policies. Our experiences illuminate the community-building potential of direct encounters and direct exchanges. The project generates ideas for becoming an inquirer in the everyday and ...
Contributing Partner: UNT Libraries
Engineered Microbial Consortium for the Efficient Conversion of Biomass to Biofuels

Engineered Microbial Consortium for the Efficient Conversion of Biomass to Biofuels

Date: August 2014
Creator: Anieto, Ugochukwu Obiakornobi
Description: Current energy and environmental challenges are driving the use of cellulosic materials for biofuel production. A major obstacle in this pursuit is poor ethanol tolerance among cellulolytic Clostridium species. The first objective of this work was to establish a potential upper boundary of ethanol tolerance for the cellulosome itself. The hydrolytic function of crude cellulosome extracts from C. cellulolyticum on carboxymethyl cellulose (CMC) with 0, 5, 10, 15, 20 and 25% (v/v) ethanol was determined. Results indicated that the endoglucanase activity of the cellulosome incubated in 5% and 10% ethanol was significantly different from a control without ethanol addition. Furthermore a significant difference was observed in endoglucanase activity for cellulosome incubated in 5%, 10%, 15%, 20% and 25% ethanol in a standalone experiment. Endoglucanase activity continued to be observed for up to 25% ethanol, indicating that cellulosome function in ethanol will not be an impediment to future efforts towards engineering increasing production titers to levels at least as high as the current physiological limits of the most tolerant ethanologenic microbes. The second objective of this work was to study bioethanol production by a microbial co-culture involving Clostridium cellulolyticum and a recombinant Zymomonas mobilis engineered for the utilization of oligodextrans. The ...
Contributing Partner: UNT Libraries
England and the International Monetary System of the Nineteenth Century

England and the International Monetary System of the Nineteenth Century

Date: May 1963
Creator: Murray, Jack W.
Description: There were two international standards in the nineteenth century, the theoretical gold standard and the historical sterling standard. The primary interest of this thesis is the latter, although the theoretical framework of the gold standard will also be examined. Because of its role in the London money market, particular attention will be given to the Bank of England. Since the Bank and the international standards were products of the evolutionary and revolutionary changes which occurred in Britain during the eighteenth and nineteenth centuries, an attempt will be made to examine them within their historical context.
Contributing Partner: UNT Libraries