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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

The loading of second-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) : to simulate the forces acting on an intermediate support tree /

Sedlak, Jerome Peter. January 1978 (has links)
Thesis (master's)--Oregon State University, 1978. / Includes bibliographical references (p. 55-57). Also available on the World Wide Web.
42

Effect of a concentrated in-service elementary teacher force and motion workshop /

Nelson, David, January 2006 (has links) (PDF)
Thesis (M.S.) in Teaching--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 65-69).
43

The Development of a Volume Element Model for Energy Systems Engineering and Integrative Thermodynamic Optimization

Unknown Date (has links)
The dissertation presents the mathematical formulation, experimental validation, and application of a volume element model (VEM) devised for modeling, simulation, and optimization of energy systems in their early design stages. The proposed model combines existing modeling techniques and experimental adjustment to formulate a reduced-order model, while retaining sufficient accuracy to serve as a practical system-level design analysis and optimization tool. In the VEM, the physical domain under consideration is discretized in space using lumped hexahedral elements (i.e., volume elements), and the governing equations for the variable of interest are applied to each element to quantify diverse types of flows that cross it. Subsequently, a system of algebraic and ordinary differential equations is solved with respect to time and scalar (e.g., temperature, relative humidity, etc.) fields are obtained in both spatial and temporal domains. The VEM is capable of capturing and predicting dynamic physical behaviors in the entire system domain (i.e., at system level), including mutual interactions among system constituents, as well as with their respective surroundings and cooling systems, if any. The VEM is also generalizable; that is, the model can be easily adapted to simulate and optimize diverse systems of different scales and complexity and attain numerical convergence with sufficient accuracy. Both the capability and generalizability of the VEM are demonstrated in the dissertation via thermal modeling and simulation of an Off-Grid Zero Emissions Building, an all-electric ship, and a vapor compression refrigeration (VCR) system. Furthermore, the potential of the VEM as an optimization tool is presented through the integrative thermodynamic optimization of a VCR system, whose results are used to evaluate the trade-offs between various objective functions, namely, coefficient of performance, second law efficiency, pull-down time, and refrigerated space temperature, in both transient and steady-state operations. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2016. / July 7, 2016. / energy systems, system-level modeling, systems engineering, thermal simulation, thermodynamic optimization, volume element model / Includes bibliographical references. / Juan C. Ordo˜nez, Professor Directing Dissertation; David A. Kopriva, University Representative; Simone P. Hruda, Committee Member; Steven W. Van Sciver, Committee Member.
44

Self-Assembly of Gold Nanoparticles into Monolayer Films

Unknown Date (has links)
Gold nanoparticles (Au NPs) are widely studied due to the ease of controlled synthesis, facile surface modification, and interesting physical properties. To fully take advantage of the NP properties, self-assembly of colloidal Au NPs into ordered structures is an essential step. Of all self-assembled structures, the two-dimensional (2D) film composed of just a single layer Au NPs is the simplest one. Yet, 2D Au NP monolayers are of key importance for both fundamental studies and numerous applications such as plasmonics, optics, sensors and catalysts. However, the self-assembly of the 2D Au NP monolayers of both microscopic (i.e. 100 nm²) and macroscopic (i.e. >cm²) order is quite challenging. The major contribution of this research is to develop effective methods to self-assemble Au NPs of various sizes into monolayers using a broad range of ligands. Two methods have been developed for this purpose, namely the "drain-to-deposit" method and the "three-phase self-assembly" technique. The resultant Au NP monolayers have been found ideal to study the polymer ligand chain configuration indicated by the interparticle space. In addition, the Au NP monolayers serve as promising surface-enhanced Raman spectroscopy (SERS) substrates and are useful to study lithium battery electrolyte s. / A Dissertation submitted to the Department of Chemical and Biomedical Engineering in partial fulfillment of the Doctor of Philosophy. / Spring Semester 2017. / March 27, 2017. / gold nanoparticle, lithium battery, polymer, self-assembly, surface-enhanced Raman scattering, thin film / Includes bibliographical references. / Daniel T. Hallinan, Jr., Professor Directing Dissertation; Jianping (Jim) Zheng, University Representative; Rufina G. Alamo, Committee Member; Jingjiao Guan, Committee Member; Zhiyong (Richard) Liang, Committee Member.
45

Essays on U.S. Renewable Energy and Local Sustainability Policy

Unknown Date (has links)
The first chapter examines what motivates airports to deploy on-site solar PV system. Currently, over 20% of U.S. public airports have adopted solar photovoltaic (PV) on their property. Yet, the vast majority of research on solar energy adoption focuses on state, local, or individual levels, largely overlooking one of the most utilized public properties for solar PV—airports. Combining a unique dataset of 488 U.S. public airports and interviews with managers at four key airports, this paper investigates why and to what degree (i.e., capacity generated) do airports deploy on-site solar PV systems. Findings suggest state-operated airports are more likely to adopt solar PV, airports in the service area of cooperatives are less likely to deploy solar PV, and the level of connectivity to other airports in airport associations positively correlates to solar PV adoption and capacity. Airport governance, support from electric utilities, and renewable policy incentives are also important factors influencing solar and renewable energy development. Policy and management implications for renewable energy deployment at airports and other publicly-used properties are discussed. Insight for future research on the general linkage between governance structure and renewable energy development is considered. The second chapter examines make-or-buy decisions (i.e., providing in-house or contracting out) in financing solar PV projects at U.S. airports. Airports are one of the fastest growing adopters of solar photovoltaic (PV) energy systems, but little is known about how airports finance solar projects. Financing arrangements can influence long-term economic viability and cost-benefit distribution of solar projects. Based on the transaction cost approach, this paper hypothesizes that make-or-buy decisions for solar projects are shaped by airport governance structure, utility ownership, state policies, and renewable market conditions. Hypotheses are examined through multinomial logistic analysis, using data from all U.S. airports that have adopted a solar PV project as of June 2018. The analysis finds that airports operated by special-purpose governments are more likely to own and self-operate solar systems, while airports in the service area of investor-owned utilities are more likely to lease land for a solar project. Statewide renewable energy regulations and solar market conditions are also important factors influencing make-or-buy decisions. This chapter has implications for solar PV policy design, taking into account positive externalities of renewable energy projects given institutional environments. The third chapter examines how local government organizational characteristics and management activities relate to public-nonprofit collaboration and perceived performance in local sustainability. Local governments have been increasingly responsible for promoting sustainability, but we are only beginning to learn how organizational characteristics and management activities influence local sustainability policy. Using 2015 sustainable cities survey data and case studies in the U.S., this study finds that public-nonprofit collaboration in sustainability is positively associated with perceived inter-departmental competition and functional fragmentation. It is also found that perceived sustainability performance is positively correlated with public-nonprofit collaboration, functional fragmentation, and performance information use. However, the relationship between performance information use and perceived performance is nonlinear, indicating that the effect of performance information use on perceived performance has an inverse u-shape. Performance information use in highly fragmented administrative arrangements may be negatively related to perceived sustainability performance. Implications for local sustainability implementation are discussed. / A Dissertation submitted to the Askew School of Public Administration and Policy in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / 2019. / [Date awarded not present on Dissertation]. / airport governance, bureaucratic competition, local sustainability, performance information, renewable energy policy, special purpose governance / Includes bibliographical references. / Richard C. Feiock, Professor Directing Dissertation; Charles Barrilleaux, University Representative; Ralph S. Brower, Committee Member; Kaifeng Yang, Committee Member.
46

A Predictive Model of Design Performance for Lithium-Ion Capacitors

Unknown Date (has links)
Recent years have seen developments in lithium-ion capacitor (LIC) technology. However, there has been scant work in mathematical models to predict the performance of LICs. Existing models have focused upon cell degradation over time or simple Randles circuits to describe laboratory work. Experimentalists have determined that LICs’ energy storage capabilities are inversely proportional to their charge or discharge (dis/charge) current. But this phenomenon is not well understood, a serious barrier to LIC market entry as designers struggle to predict the energy storage of LICs under design. This study begins with an experiment on applying lithium to LICs. Then it discusses a study on the cycle life of LICs. Earlier studies had found the degradation of LICs cycled at constant current but different temperatures can be described by an Arrhenius equation. This cycle life study found that when an LIC is cycled at a constant temperature but different cycle currents the results can also be described by an Arrhenius equation, which can be derived from the Arrhenius equation describing degradation as a function of current. The Butler-Volmer equation anticipates these results because it predicts direct proportionality between a LIC’s cycle current and temperature. The predictive model, which comprises the bulk of this research, began with electrochemical impedance spectroscopy experiments (EIS) on an LIC to build a Randles equivalent circuit model (ECM) describing the same LIC. This LIC was then charged at several constant powers, recording the stored energy. Using the Randles ECM, simulated LICs were charged at these same constant powers, yielding high fidelity at low power but significant error at high power. In order to solve this high power inaccuracy, all of the experimentally-derived values, except for the series resistance and Warburg resistance, were replaced by physics equations that would compute these values. The Butler-Volmer equation was manipulated to express dis/charge current in terms of temperature, which computed the Warburg capacitance and dis/charge transfer resistance, key elements in a Randles ECM. This change yielded an accurate energy computation, but not an accurate voltage computation. Furthermore, the temperature values computed by the Butler-Volmer equation were unrealistic and could not be reconciled mathematically. The next iteration of the study involved in situ temperature measurements of LICs during dis/charge cycles. These in situ measurements indicated that temperature change is only observed during low power dis/charges, and even then it is <1% of absolute temperature. This indicates that although the Butler-Volmer equation can express LIC temperature in terms of dis/charge current, temperature can be treated as a constant without much loss in model fidelity. Warburg impedance was observed to be computed in terms of temperature and is almost constant, like temperature. Series resistance negligibly affects voltage change or energy stored in an LIC. This is the first known physics-based model to predict an LIC’s energy storage as a function of its dis/charge current and constituent components. This model also explains the current-energy inverse relationship observed in LICs using a new derivation of the Butler-Volmer equation. This model may have significant commercial value for LIC designers in the future as it eliminates a significant barrier to market entry. / A Dissertation submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / 2019 / October 3, 2019. / Arrhenius equation, Butler-Volmer equation, lithium-ion capacitor, model, Randles equivalent circuit model, Warburg impedance / Includes bibliographical references. / Simon Foo, Professor Directing Dissertation; Anke Meyer-Baese, University Representative; Petru Andrei, Committee Member; Rodney Roberts, Committee Member; Zhibin Yu, Committee Member.
47

Analytical study of the energy-weight and energy-volume characteristics of energy storage systems /

Kline, Leo Virgil January 1954 (has links)
No description available.
48

Energy expenditures of women performing household floor-care activities /

Ray, Johnnie Nell January 1962 (has links)
No description available.
49

Energy moment treatment of the quantum mechanical asymmetric rotator /

Parker, Paul Michael January 1958 (has links)
No description available.
50

The effects of hand-wrist and body orientation on the force requirements to perform a push-pull task

Day, Robert Alan. January 1965 (has links)
Call number: LD2668 .T4 1965 D27 / Master of Science

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