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Full-Text Articles in Engineering

Behavior And Design Of Steel-Plate Composite (Sc) Walls For Blast Loads, Jakob C Bruhl Apr 2015

Behavior And Design Of Steel-Plate Composite (Sc) Walls For Blast Loads, Jakob C Bruhl

Open Access Dissertations

Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental and analytical ...


Control Of Modular Multilevel Converters For Grid Integration Of Full-Scale Wind Energy Conversion Systems, Suman Debnath Apr 2015

Control Of Modular Multilevel Converters For Grid Integration Of Full-Scale Wind Energy Conversion Systems, Suman Debnath

Open Access Dissertations

The growing demand for wind power generation has pushed the capacity of wind turbines towards MW power levels. Higher capacity of the wind turbines necessitates operation of the generators and power electronic conversion systems at higher voltage/power levels. The power electronic conversion system of a wind energy conversion system (WECS) needs to meet the stringent requirements in terms of reliability, efficiency, scalability and ease of maintenance, power quality, and dv/dt stress on the generator/transformer. Although the multilevel converters including the neutral point clamped (NPC) converter and the active NPC converter meet most of the requirements, they fall ...


Kesterite Thin-Film Solar Cell Absorbers Derived Using Inhomogeneous Czts Nanoparticles, Wei-Chang D. Yang Jan 2015

Kesterite Thin-Film Solar Cell Absorbers Derived Using Inhomogeneous Czts Nanoparticles, Wei-Chang D. Yang

Open Access Dissertations

My doctoral research focuses on understanding the structure-property-processing relationship of the kesterite materials to improve their device performance. It is recognized in both my own work and the recent literature that the structural and compositional integrities of CZTSSe are crucial to derive the solar cell grade kesterite thin-films. Analytical electron microscopy (AEM) allows me to demonstrate the structural and compositional inhomogeneity of the CZTS nanoparticles and CZTSSe thin-films at the nanoscale. For example, the observed forbidden reflections in TED patterns and FFT diffractograms corresponding to HRTEM images indicate that cation disorder leads to stacking faults in CZTS nanoparticles. Probe-corrected STEM ...


Tools For Efficient Design Of Multicomponent Separation Processes, Joshua Lee Huff Oct 2014

Tools For Efficient Design Of Multicomponent Separation Processes, Joshua Lee Huff

Open Access Dissertations

Separations account for as much as 85% of plant operating costs in chemical production; it is therefore important that they be designed with energy efficiency in mind. This can only be achieved if two things are achieved: the complete space of design options is known, and an accurate way is developed to compare all possible design options. For both membrane separation cascades and multicomponent distillation configurations, this dissertation explores methods for designing energy efficient separations.^ The operating cost of membranes used in production of nitrogen gas from air is largely driven by the compressors required to maintain a pressure differential ...


Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz Oct 2014

Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz

Open Access Dissertations

Personal transport is a leading contributor to fossil fuel consumption and greenhouse (GHG) emissions in the U.S. The U.S. Energy Information Administration (EIA) reports that light-duty vehicles (LDV) are responsible for 61\% of all transportation related energy consumption in 2012, which is equivalent to 8.4 million barrels of oil (fossil fuel) per day. The carbon content in fossil fuels is the primary source of GHG emissions that links to the challenge associated with climate change. Evidently, it is high time to develop actionable and innovative strategies to reduce fuel consumption and GHG emissions from the road transportation ...


Solar Cell Temperature Dependent Efficiency And Very High Temperature Efficiency Limits, John Robert Wilcox Oct 2013

Solar Cell Temperature Dependent Efficiency And Very High Temperature Efficiency Limits, John Robert Wilcox

Open Access Dissertations

Clean renewable solar energy is and will continue to be a critically important source of electrical energy. Solar energy has the potential of meeting all of the world's energy needs, and has seen substantial growth in recent years. Solar cells can convert sun light directly into electrical energy, and much progress has been made in making them less expensive and more efficient. Solar cells are often characterized and modeled at 25 °C, which is significantly lower than their peak operating temperature. In some thermal concentrating systems, solar cells operate above 300 °C. Since increasing the temperature drastically affects the ...


Effect Of Building Morphology On Energy And Structural Performance Of High-Rise Office Buildings, Mohamed Krem May 2012

Effect Of Building Morphology On Energy And Structural Performance Of High-Rise Office Buildings, Mohamed Krem

Open Access Dissertations

The civil engineering and architectural communities are highly focused, these days, on designing buildings that maximize utilization of energy available from natural resources. This dissertation presents a quantitative study of the effect of high-rise office building morphology on energy and structural performances for the major climates. The parameters of the building morphologies are varied - the building footprint shape, the placement of the structural core/walls, and the building orientation. The energy analysis is performed using Autodesk Ecotect Analysis 2011; while using SAP2000 for the structure analysis and design. The key observations are: 1) the building morphology has a significant effect ...