Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

144,533 Full-Text Articles 166,088 Authors 56,080,941 Downloads 298 Institutions

All Articles in Engineering

Faceted Search

144,533 full-text articles. Page 4128 of 4141.

The Relevance Of Time-To-Digital Converters To Small Platform Direction Finding Systems, Paul Jeffrey Nelson 2010 University of Central Florida

The Relevance Of Time-To-Digital Converters To Small Platform Direction Finding Systems, Paul Jeffrey Nelson

Electronic Theses and Dissertations

This thesis explores a Time-Difference-of-Arrival (TDOA) approach to radio direction finding, utilizing picosecond-resolution Time-to-Digital Converters (TDCs). By measuring the relative time of arrival of a pulsed RF signal impinging on an antenna array, direction of arrival (DOA) can be ascertained. This technology enables versatile DOA calculation on platforms only several meters in length, and offers various size, weight, power, and cost advantages when compared to present DF technologies. A short baseline S-band TDOA DF system utilizing TDCs is designed, fabricated, and tested in a laboratory environment. This research suggests that such a DF system based on TDCs provides sufficient accuracy ...


Foundation Design For High Tension Cable Guardrails, John R. Rohde Ph.D., P.E., Ling Zhu Ph.D., Ryan J. Terpsma B.S.M.E 2010 University of Nebraska - Lincoln

Foundation Design For High Tension Cable Guardrails, John R. Rohde Ph.D., P.E., Ling Zhu Ph.D., Ryan J. Terpsma B.S.M.E

Final Reports & Technical Briefs from Mid-America Transportation Center

High tension cable guardrail is becoming increasing popular in median and roadside applications due to the promise of reduced deflections upon impact and reduced maintenance. As the performance of these systems is observed in service, there is a growing concern over the end anchorage foundation performance of current systems. Foundations for high tension systems must not only be capable of restraining the impact load of a vehicle but must also restrain the initial pretension on the cable system as well as temperature induced loads. While it may be acceptable for many roadside safety devices to require foundation repair after impact ...


Characterization Of Aluminum Doped Zinc Oxide Thin Films For Photovoltaic Applications, Bojanna P. Shantheyanda 2010 University of Central Florida

Characterization Of Aluminum Doped Zinc Oxide Thin Films For Photovoltaic Applications, Bojanna P. Shantheyanda

Electronic Theses and Dissertations

Growing demand for clean source of energy in the recent years has increased the manufacture of solar cells for converting sun energy directly into electricity. Research has been carried out around the world to make a cheaper and more efficient solar cell technology by employing new architectural designs and developing new materials to serve as light absorbers and charge carriers. Aluminum doped Zinc Oxide thin film, a Transparent conductive Oxides (TCO) is used as a window material in the solar cell these days. Its increased stability in the reduced ambient, less expensive and more abundance make it popular among the ...


Mechanical Properties Of Carbon Nanotube/Metal Composites, Ying Sun 2010 University of Central Florida

Mechanical Properties Of Carbon Nanotube/Metal Composites, Ying Sun

Electronic Theses and Dissertations

Carbon nanotubes (CNTs) have captured a great deal of attention worldwide since their discovery in 1991. CNTs are considered to be the stiffest and strongest material due to their perfect atomic arrangement and intrinsic strong in-plane sp 2—sp 2 covalent bonds between carbon atoms. In addition to mechanical properties, CNTs have also shown exceptional chemical, electrical and thermal properties. All these aspects make CNTs promising candidates in the development of novel multi-functional nanocomposites. Utilizing CNTs as fillers to develop advanced nanocomposites still remains a challenge, due to the lack of fundamental understanding of both material processing at the nanometer ...


Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi 2010 University of Central Florida

Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi

Electronic Theses and Dissertations

Molybdenum (Mo) thin film back contact layers for thin film CuIn(1-x)GaxSe2 (CIGS) solar cells were deposited onto soda lime glass substrates using a direct current (DC) planar magnetron sputtering deposition technique. Requirements for the Mo thin film as a back contact layer for CIGS solar cells are various. Sheet resistance, contact resistance to the CIGS absorber, optical reflectance, surface morphology, and adhesion to the glass substrate are the most important properties that the Mo thin film back contact layer must satisfy. Experiments were carried out under various combinations of sputtering power and working gas pressure, for it is ...


Second Generation Precast Deck Panel (Nudeck) System, Maher K. Tadros Ph.D., P.E., Kromel E Hanna, George Morcous Ph.D. 2010 University of Nebraska - Lincoln

Second Generation Precast Deck Panel (Nudeck) System, Maher K. Tadros Ph.D., P.E., Kromel E Hanna, George Morcous Ph.D.

Final Reports & Technical Briefs from Mid-America Transportation Center

The majority of today’s bridge decks are built using cast-in-place concrete construction. This is due to the perceived low initial cost and constructor familiarity with the system. This research report describes the design, details, and construction of an innovative full-depth precast concrete bridge deck system – the Second Generation NUDECK (Nebraska University Deck). The quality of this system is far superior to castin- place construction. Cast-in-place concrete bridge decks experience cracking shortly after construction due to differential creep and shrinkage with the supporting beams. This leads to bridge deck deterioration; a problem that is not experienced with the virtually crack-free ...


Estimating Highway Pavement Damage Costs Attributed To Truck Traffic, Yong Bai, Steven D. Schrock, Thomas E. Mulinazzi, Wenhua Hou, Chunxiao Liu, Umar Firman 2010 University of Kansas

Estimating Highway Pavement Damage Costs Attributed To Truck Traffic, Yong Bai, Steven D. Schrock, Thomas E. Mulinazzi, Wenhua Hou, Chunxiao Liu, Umar Firman

Final Reports & Technical Briefs from Mid-America Transportation Center

Kansas is one of the leaders in meat production in the United States. In the southwest Kansas region, there are more than three hundred feed yards and several of the biggest meat processing plants in the nation. Heavy trucks (e.g., tractor-trailers) have been used primarily for transporting processed meat, meat byproducts, grain, and other related products. With the continuous growth of these industries, there will be more trucks on highways transporting meat and meat-related products in southwest Kansas. These trucks cause noteworthy damage to Kansas highway pavements, which in turn leads to more frequent maintenance actions and ultimately more ...


Extending Asphalt Pavement Life Using Thin Whitetopping, Mustaque Hossain, Sharmin Sultana 2010 Kansas State University

Extending Asphalt Pavement Life Using Thin Whitetopping, Mustaque Hossain, Sharmin Sultana

Final Reports & Technical Briefs from Mid-America Transportation Center

Due to budget constraints, many highway agencies are becoming interested in pavement preservation or rehabilitation rather than reconstruction to ensure pavement is in serviceable condition. Thin whitetopping (TWT) is the process of rehabilitating distressed asphalt concrete (AC) pavements by using a concrete overlay. This study was done to develop a design catalog for existing AC pavements to be overlaid with TWT. The finite element (FE) analysis was performed with SolidWorks, which is the 3-D FE software program used to develop this design catalog. The design considered different TWT thicknesses, existing AC layer thickness and modulus, the bonding condition between TWT ...


Assessing The Damage Potential In Pretensioned Bridges, Caused By Increased Truck Loads Due To Freight Movements (Phase I), Robert J. Peterman, Steven Hammerschmidt 2010 Kansas State University

Assessing The Damage Potential In Pretensioned Bridges, Caused By Increased Truck Loads Due To Freight Movements (Phase I), Robert J. Peterman, Steven Hammerschmidt

Final Reports & Technical Briefs from Mid-America Transportation Center

When evaluating the condition of existing bridges determining in situ stresses in the members provides valuable information about the condition of the structures. In this study, a method of surface strain relief was investigated whereby the change in strain at the surface of concrete members is used to determine the in situ stress. The method involved mounting a linear electrical-resistance strain gage along the axis of maximum stress, coring around the gage, and then relating the change in strain to the corresponding stress in the member. Members were fabricated and varying stresses were applied in order to determine the accuracy ...


Analysis And Optimization Of A Solar Thermal Collector With Integrated Storage, Monica Bonadies 2010 University of Central Florida

Analysis And Optimization Of A Solar Thermal Collector With Integrated Storage, Monica Bonadies

Electronic Theses and Dissertations

Solar energy, a topic popular in the United States during the oil embargo of the 1970’s, has become a relevant topic once more with the current focus on reducing greenhouse emissions. Solar thermal energy in particular has become popular as it uses existing steam turbine technology to produce electricity, with the benefit of using solar energy to produce steam rather than coal or nuclear heat sources. Solar thermal can also be used at lower temperatures to heat water for pools or for residential use. While this energy source has its benefits, it has the problem of being opportunistic – the ...


Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu 2010 University of Central Florida

Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu

Electronic Theses and Dissertations

The general goal of this dissertation is to provide a comprehensive description of the limitations of established theories on bound electronic nonlinearities in direct-gap semiconductors by performing various experiments on wide and narrow bandgap semiconductors along with developing theoretical models. Nondegenerate two-photon absorption (2PA) is studied in several semiconductors showing orders of magnitude enhancement over the degenerate counterpart. In addition, three-photon absorption (3PA) is studied in ZnSe and other semiconductors and a new theory using a Kane 4-band model is developed which fits new data well. Finally, the narrow gap semiconductor InSb is studied with regard to multiphoton absorption, free-carrier ...


New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir 2010 University of Central Florida

New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir

Electronic Theses and Dissertations

The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold ...


Characteristics And Contributory Causes Related To Large Truck Crashes (Phase I) -Fatal Crashes, Sundanda Dissanayake Ph.D., P.E. 2010 Kansas State University

Characteristics And Contributory Causes Related To Large Truck Crashes (Phase I) -Fatal Crashes, Sundanda Dissanayake Ph.D., P.E.

Final Reports & Technical Briefs from Mid-America Transportation Center

One-ninth of all traffic fatalities in the United States have involved large trucks in the past five years, although large trucks contributed to only 3% of registered vehicles and 7% of vehicle miles travelled. This contrasting proportion indicates that truck crashes in general tend to be more severe than other crashes though they constitute a smaller sector of vehicles on the road. To study this issue, fatal crash data from the FARS was used to analyze characteristics and factors contributing to truck-involved crashes. Driver, vehicle, and crash-related contributory causes were identified, and as an extension the likelihood of occurrence of ...


A Decision Support System Methodology For The Selection Of Rapid Prototyping Technologies For Investment-Cast Gas Turbine Parts, Angela Gallagher 2010 University of Central Florida

A Decision Support System Methodology For The Selection Of Rapid Prototyping Technologies For Investment-Cast Gas Turbine Parts, Angela Gallagher

Electronic Theses and Dissertations

In the power generation sector, more specifically, the gas turbine industry, competition has forced the lead time-to-market for product advancements to be more important than ever. For design engineers, this means that product design iterations and final product development must be completed within both critical time windows and budgetary constraints. Therefore, two areas that have received significant attention in the research and in practice are: (1) rapid prototyping technology development, and (2) rapid prototyping technology selection. Rapid prototyping technology selection is the focus of this research. In practice, selecting the rapid prototyping method that is acceptable for a specific design ...


Toward A Real-Time Celestial Body Information System, Brian Mitchell Guise 2010 University of Central Florida

Toward A Real-Time Celestial Body Information System, Brian Mitchell Guise

Electronic Theses and Dissertations

The National Aeronautics and Space Administration maintains a challenging schedule of planned and on-going space exploration missions that extend to the outer reaches of our galaxy. New missions represent a huge investment, in terms of actual costs for equipment and support infrastructure, and personnel training. The success of a mission is critical considering both the monetary investment, and for manned missions, the lives which are put at risk. Tragedies involving Challenger, Columbia, Apollo 7, and the near tragedy of Apollo 13 exemplify that space exploration is a dangerous endeavor, posing extreme environmental conditions on both equipment and personnel. NASA, the ...


Three-Port Micro-Inverter With Power Decoupling Capability For Photovoltaic (Pv) Systems Applications, Souhib Harb 2010 University of Central Florida

Three-Port Micro-Inverter With Power Decoupling Capability For Photovoltaic (Pv) Systems Applications, Souhib Harb

Electronic Theses and Dissertations

The Photovoltaic (PV) systems have been realized using different architectures, starting with the string and centralized PV system to the modular PV system. Presently, decentralized inverters are being developed at the PV panel power level (known as AC – PV Modules). Such new PV systems are becoming more attractive and many expect this will be the trend of the future. The AC-Module PV system consists of an inverter attached to one PV panel. This integration requires that both devices have the same life-span. Although, the available commercial inverters have a relatively short life-span (10 years) compared to the 25 –year PV ...


Robust Dialog Management Through A Context-Centric Architecture, Victor C. Hung 2010 University of Central Florida

Robust Dialog Management Through A Context-Centric Architecture, Victor C. Hung

Electronic Theses and Dissertations

This dissertation presents and evaluates a method of managing spoken dialog interactions with a robust attention to fulfilling the human user’s goals in the presence of speech recognition limitations. Assistive speech-based embodied conversation agents are computer-based entities that interact with humans to help accomplish a certain task or communicate information via spoken input and output. A challenging aspect of this task involves open dialog, where the user is free to converse in an unstructured manner. With this style of input, the machine’s ability to communicate may be hindered by poor reception of utterances, caused by a user’s ...


Tuning The Properties Of Nanomaterials As Function Of Surface And Environment, Ajay Karakoti 2010 University of Central Florida

Tuning The Properties Of Nanomaterials As Function Of Surface And Environment, Ajay Karakoti

Electronic Theses and Dissertations

Nanotechnology has shaped the research and development in various disciplines of science and technology by redefining the interdisciplinary research. It has put the materials science at the forefront of technology by allowing the researchers to engineer materials with properties ranging from electronics to biomedical by using materials as diverse as ceramics to just plain carbon. These exceptional properties are achieved by minimizing the dimension of particles in such smaller domains that the boundary between the individual atoms, ions or cluster of particles is very small. This results in a change in conventional properties of particles from continuum physics to quantum ...


Extending Pavement Life Using Thin Surfacing To Counter The Effect Of Increased Truck Traffic Due To Freight Movements On Highways, Mustaque Hossain Ph.D., P.E., Vikranth S. Manepalli, Shaidur Rahman, Haritha Y. Musty 2010 Kansas State University

Extending Pavement Life Using Thin Surfacing To Counter The Effect Of Increased Truck Traffic Due To Freight Movements On Highways, Mustaque Hossain Ph.D., P.E., Vikranth S. Manepalli, Shaidur Rahman, Haritha Y. Musty

Final Reports & Technical Briefs from Mid-America Transportation Center

The highways in the Midwest are experiencing a considerable amount of truck traffic due to increased freight transportation. There is clearly a risk to the highway infrastructure caused by this additional truck traffic that will also have an increasingly detrimental effect on the safety of the citizens, the traveling public in terms of congestion, and the economy of the entire region. Traditionally the life of the pavements has been extended by a variety of rehabilitation techniques. For example, techniques used by the Kansas Department of Transportation (KDOT) include route and crack seal, chip seal, 1- to 4-inch overlay, 1- to ...


Bit-Rate Aware Reconfigurable Architecture For H.264/Avc Deblocking Filter, Rakan Khraisha 2010 University of Central Florida

Bit-Rate Aware Reconfigurable Architecture For H.264/Avc Deblocking Filter, Rakan Khraisha

Electronic Theses and Dissertations

In H.264/AVC, DeBlocking Filter (DBF) achieves bit rate savings and it is used to improve visual quality by reducing the presence of blocking artifacts. However, these advantages come at the expense of increasing computational complexity of the DBF due to highly adaptive mode decision and small 4x4 block size. The DBF easily accounts for one third of the computational complexity of the decoder. The computational complexity required for various target applications from mobile to high definition video applications varies significantly. Therefore, it becomes apparent to design efficient architecture to adapt to different requirements. In this work, we exploit ...


Digital Commons powered by bepress