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2007

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Articles 2521 - 2550 of 3831

Full-Text Articles in Engineering

A Hybrid Routing Protocol For Communications Among Nodes Withhigh Relative Speed In Wireless Mesh Networks, Nikolaos Peppas Jan 2007

A Hybrid Routing Protocol For Communications Among Nodes Withhigh Relative Speed In Wireless Mesh Networks, Nikolaos Peppas

Electronic Theses and Dissertations

Wireless mesh networks (WMN) is a new promising wireless technology which uses already available hardware and software components. This thesis proposes a routing algorithm for military applications. More specifically, a specialized scenario consisting of a network of flying Unmanned Aerial Vehicles (UAVs) executing reconnaissance missions is investigated. The proposed routing algorithm is hybrid in nature and uses both reactive and proactive routing characteristics to transmit information. Through simulations run on a specially built stand alone simulator, based on Java, packet overhead, delivery ratio and latency metrics were monitored with respect to varying number of nodes, node density and mobility. The …

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Behavior Of Variable-Length Genetic Algorithms Under Random Selection, Harold Stringer Jan 2007

Behavior Of Variable-Length Genetic Algorithms Under Random Selection, Harold Stringer

Electronic Theses and Dissertations

In this work, we show how a variable-length genetic algorithm naturally evolves populations whose mean chromosome length grows shorter over time. A reduction in chromosome length occurs when selection is absent from the GA. Specifically, we divide the mating space into five distinct areas and provide a probabilistic and empirical analysis of the ability of matings in each area to produce children whose size is shorter than the parent generation's average size. Diversity of size within a GA's population is shown to be a necessary condition for a reduction in mean chromosome length to take place. We show how a …

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Evaluating The Impact Of Oocea S Dynamic Message Signs (Dms) On Travelers Experience Using The Pre-Deployment Survey, John Hill Rogers Jan 2007

Evaluating The Impact Of Oocea S Dynamic Message Signs (Dms) On Travelers Experience Using The Pre-Deployment Survey, John Hill Rogers

Electronic Theses and Dissertations

The purpose of this thesis was to evaluate the impact of dynamic message signs (DMS) on the Orlando-Orange County Expressway Authority (OOCEA) toll road network using the Pre-Deployment DMS Survey (henceforth referred to as "pre-deployment survey"). DMS are electronic traffic signs used on roadways to give travelers information about travel times, traffic congestion, accidents, disabled vehicles, AMBER alerts, and special events. The particular DMS referred to in this study are large rectangular signs installed over the travel lanes and these are not the portable trailer mount signs. The OOCEA is currently in the process of adding several fixed DMS on …

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Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices, Ravi Todi Jan 2007

Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices, Ravi Todi

Electronic Theses and Dissertations

The continued scaling of device dimensions in complementary metal oxide semiconductor (CMOS) technology within the sub-100 nm region requires an alternative high dielectric constant (high-k) oxide layer to counter high tunneling leakage currents, a metallic gate electrode to address polysilicon depletion, boron penetration and high polysilicon sheet resistance, and high mobility channel materials to boost the CMOS performance. Metal gates can also offer improved thermal and chemical stability, but their use requires that we improve our understanding of how the metal alloy phase, crystallographic orientation, and composition affect the electronic properties of the metal alloy-oxide interface. To replace n++ and …

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Target Element Sizes For Finite Element Tidal Models From A Domain-Wide, Localized Truncation Error Analysis Incorporating Botto, Denwood Parrish Jan 2007

Target Element Sizes For Finite Element Tidal Models From A Domain-Wide, Localized Truncation Error Analysis Incorporating Botto, Denwood Parrish

Electronic Theses and Dissertations

A new methodology for the determination of target element sizes for the construction of finite element meshes applicable to the simulation of tidal flow in coastal and oceanic domains is developed and tested. The methodology is consistent with the discrete physics of tidal flow, and includes the effects of bottom stress. The method enables the estimation of the localized truncation error of the nonconservative momentum equations throughout a triangulated data set of water surface elevation and flow velocity. The method's domain-wide applicability is due in part to the formulation of a new localized truncation error estimator in terms of complex …

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A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney Jan 2007

A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney

Electronic Theses and Dissertations

The motivation behind this thesis is to consolidate and evaluate the most common Proportional Integral Derivative (PID) controller tuning techniques used in industry. These are the tuning techniques used when the plant transfer function is not known. Many of these systems are poorly tuned because such consolidated information is not easily found in one single source such as this thesis. Once one of the tuning methods are applied almost always there will be further fine tuning needed to bring the system into the required design criteria. The purpose here is to find out which tuning technique will yield the lowest …

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A Framework For The Assessment And Analysis Of Multi-Hazardsinduced Risk Resulting From Space Vehicles Operations, Serge Sala-Diakanda Jan 2007

A Framework For The Assessment And Analysis Of Multi-Hazardsinduced Risk Resulting From Space Vehicles Operations, Serge Sala-Diakanda

Electronic Theses and Dissertations

With the foreseeable increase in traffic frequency to and from orbit, the safe operation of current and future space vehicles at designated spaceports has become a serious concern. Due to their high explosive energy potential, operating those launch vehicles presents a real risk to: (1) the spaceport infrastructure and personnel, (2) the communities surrounding the spaceport and (3) the flying aircrafts whose routes could be relatively close to spaceport launch and reentry routes. Several computer models aimed at modeling the effects of the different hazards generated by the breakup of such vehicles (e.g., fragmentation of debris, release of toxic gases, …

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Negative Bias Temperature Instability And Charge Trapping Effects On Analog And Digital Circuit Reliability, Yixin Yu Jan 2007

Negative Bias Temperature Instability And Charge Trapping Effects On Analog And Digital Circuit Reliability, Yixin Yu

Electronic Theses and Dissertations

Nanoscale p-channel transistors under negative gate bias at an elevated temperature show threshold voltage degradation after a short period of stress time. In addition, nanoscale (45 nm) n-channel transistors using high-k (HfO2) dielectrics to reduce gate leakage power for advanced microprocessors exhibit fast transient charge trapping effect leading to threshold voltage instability and mobility reduction. A simulation methodology to quantify the circuit level degradation subjected to negative bias temperature instability (NBTI) and fast transient charge trapping effect has been developed in this thesis work. Different current mirror and two-stage operation amplifier structures are studied to evaluate the impact of NBTI …

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Biostability In Drinking Water Distribution Systems In A Changing Water Quality Environment Using Corrosion Inhibitors, Bingjie Zhao Jan 2007

Biostability In Drinking Water Distribution Systems In A Changing Water Quality Environment Using Corrosion Inhibitors, Bingjie Zhao

Electronic Theses and Dissertations

In this study, the bacterial growth dynamics of 14 pilot drinking water distribution systems were studied in order to observe water quality changes due to corrosion inhibitor addition. Empirical models were developed to quantity the effect of inhibitor type and dose on bacterial growth (biofilm and bulk water). Water and pipe coupon samples were taken and examined during the experiments. The coupons were exposed to drinking water at approximately 20°C for at least 5 weeks to allow the formation of a measurable quasi- steady-state biofilm. Bulk water samples were taken every week. In this study, two simple but practical empirical …

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The Effect Of The Rate Of Precursor Production On The Purity And Aggregation Morphology Of Nanoparticulate Zinc Oxide, Grainne Duffy, Suresh Pillai, Declan Mccormack Jan 2007

The Effect Of The Rate Of Precursor Production On The Purity And Aggregation Morphology Of Nanoparticulate Zinc Oxide, Grainne Duffy, Suresh Pillai, Declan Mccormack

Articles

The synthesis of zinc oxide through the decomposition of a solid oxalate precursor was
investigated. It was found that the rate of preparation of the precursor had a quantitative effect on
the morphology and extent of surface ligation of particles produced; contrary to our expectations,
it was found that the slow combination of reagents led to a less pure product. It has been
determined that this time dependence mimics the variation of reactant ratios. Zinc oxide particles
were produced from a number of reactant ratios, and were characterised by TEM, XRD, FT-IR
and DSC. It was found that the size …

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Engineering - An Inherently Philosophical Enterprise, William Grimson Jan 2007

Engineering - An Inherently Philosophical Enterprise, William Grimson

Books/Book chapters

No abstract provided.

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A Novel Wideband Semi-Planar Miniaturized Antenna, Giuseppe Ruvio, Max Ammann Jan 2007

A Novel Wideband Semi-Planar Miniaturized Antenna, Giuseppe Ruvio, Max Ammann

Articles

A semi-planar miniaturized antenna which operates over the FCC allocated UWB spectrum is presented. The small antenna comprises a folded conducting element connected to a printed section. Several solutions are introduced which create different current paths increasing the effective dimensions of the antenna. The antenna is examined for the stand-alone case and for the antenna mounted in various locations on a larger handset-type groundplane. The impedance and radiation characteristics show a relative independence of the groundplane size and the antenna location on it. The proposed antenna is a valuable candidate for handset applications due to its compactness. The proposed antenna …

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Reinventing A Level 7 Programme In Electrical Engineering And Greatly Improving On Student Retention, Eugene Coyle, Mike Murphy, Frank Costello, Leslie Shoemaker Jan 2007

Reinventing A Level 7 Programme In Electrical Engineering And Greatly Improving On Student Retention, Eugene Coyle, Mike Murphy, Frank Costello, Leslie Shoemaker

Books/Book chapters

Following the successful implementation over a number of decades of a three-year Diploma in Electrical and Control Engineering at Technological University Dublin, the programme entered a period of extreme difficulty and uncertainty in the late nineteen ninetees and early years of the new millennium. As with many such engineering programmes, student numbers seeking to enter began to diminish. Furthermore, engagement and retention of students who had enrolled on the programme became evermore challenging, necessitating some radical moves in the formation and operation of the programme and in putting additional student support mechanisms in place. The situation hit rock bottom between …

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European And American Perspectives On Engineering Technology Vs Engineering Degrees, Michael Dyrenfurth, Mike Murphy, Robert Herrick, Manfred Hamann Jan 2007

European And American Perspectives On Engineering Technology Vs Engineering Degrees, Michael Dyrenfurth, Mike Murphy, Robert Herrick, Manfred Hamann

Conference papers

No abstract provided.

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Engineering Science As Opposed To Natural Science, Eugene Coyle, Mike Murphy, William Grimson Jan 2007

Engineering Science As Opposed To Natural Science, Eugene Coyle, Mike Murphy, William Grimson

Presentations

No abstract provided.

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The Use Of Thermoelectric Peltiers To Recapture Waste Heat, Navarre Bartz Jan 2007

The Use Of Thermoelectric Peltiers To Recapture Waste Heat, Navarre Bartz

Opportunities for Undergraduate Research Experience Program (OURE)

Peltier devices are a method of converting differences in temperature into electrical energy. Using data from a supplier of these devices, calculations were made to determine the efficiency of these devices in conjunction with a residential solar hybrid electric system. The initial calculations show efficiencies less than 2% with the temperature differences experienced during the springtime. While this efficiency doesn't sound stellar, taking into account the current efficiency of residential solar cells, this would be an appreciable addition to the power output of a residential solar system.

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Durability Performance Of Polyurea Confined Concrete Cylinders, Matthew Beyer Jan 2007

Durability Performance Of Polyurea Confined Concrete Cylinders, Matthew Beyer

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.

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Mechanical Fastener Pull-Out In Recycled Plastic Lumber, Ryan Dusheke Jan 2007

Mechanical Fastener Pull-Out In Recycled Plastic Lumber, Ryan Dusheke

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this paper is to present test results for the examination of mechanical fastener pull-out in plastic lumber. The testing was performed on both 1 Od galvanized steel nails, nominally 3" long and 0.148" in diameter, and No. 10 flathead low-carbon steel screws, nominally I" long. l "x6" Trimax plastic lumber, produced by US Plastic Lumber, was used for all testing. Tests were performed in each of the three sides of the boards. To evaluate the performance of the materials in varying conditions, testing was performed at -20°f, room temperature, and 125°f.

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Computational Study Of Laminar Separation Bubble Development Over Supersonic Airfoils At Subsonic Speeds, Josiah D. Elliott Jan 2007

Computational Study Of Laminar Separation Bubble Development Over Supersonic Airfoils At Subsonic Speeds, Josiah D. Elliott

Opportunities for Undergraduate Research Experience Program (OURE)

Laminar Separation Bubbles (LSBs) are regions of separated flow that start near the leading edge of an airfoil and reattach further down the airfoil surface. These regions of separation can appear at low angles of attack and can grow significantly as the angle of attack is increased heavily influencing the flow characteristics over the airfoil. Research on this topic is driven by the supersonic business jet industry which has a particular interest in this type of research due to performance requirements in both the subsonic and supersonic flight regimes. This manuscript is focused on the flow developments near the sharp …

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Analysis Of Vertical Takeoff And Landing (Vtol) Unmanned Aerial Vehicles (Ua V) With Emphasis On Tilt Duct And Tilt Rotor Systems, Devin Boyle Jan 2007

Analysis Of Vertical Takeoff And Landing (Vtol) Unmanned Aerial Vehicles (Ua V) With Emphasis On Tilt Duct And Tilt Rotor Systems, Devin Boyle

Opportunities for Undergraduate Research Experience Program (OURE)

No abstract provided.

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Growth Of Mc3t3-El Pre-Osteoblasts On Borate Containing Glasses & Growth Of Osteoblastic Cells On 13-93 Glass Scaffolds, Agatha Dwilewicz Jan 2007

Growth Of Mc3t3-El Pre-Osteoblasts On Borate Containing Glasses & Growth Of Osteoblastic Cells On 13-93 Glass Scaffolds, Agatha Dwilewicz

Opportunities for Undergraduate Research Experience Program (OURE)

Three borate-based glasses, compositions designated 1B, 2B, and 3B, with B203 levels of 15, 31, and 46 mole percent (Table 1), respectively, were tested for their effects on the growth of MC3T3-El mouse pre-osteoblastic cells under physiological fluid conditions. Silicate type 45S5 glass was used as a control for comparison. Independently, the biocompatibility of recently developed silicate-based porous 13-93 bioactive glass scaffolds was tested; Saos-2 human osteosarcoma cell line was used. Tests performed for the two studies included: contact assays of cell growth at the glass interface, chemical analysis of borate released into the culture medium, quantitative …

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Steel Deck Institute Design Manual For Composite Decks, Form Decks, And Roof Decks, Steel Deck Institute Jan 2007

Steel Deck Institute Design Manual For Composite Decks, Form Decks, And Roof Decks, Steel Deck Institute

Steel Deck Institute (SDI) Specifications and Manuals (1939 - present)

No abstract provided.

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Performance Of Steel Products Coated With Zinc And Zinc Alloys In Pressure Treated Wood, Nahb Research Center, Inc. Jan 2007

Performance Of Steel Products Coated With Zinc And Zinc Alloys In Pressure Treated Wood, Nahb Research Center, Inc.

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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Polarisation Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell Jan 2007

Polarisation Dependence Of Bend Loss For A Standard Singlemode Fiber, Qian Wang, Ginu Rajan, Pengfei Wang, Gerald Farrell

Articles

Polarization dependence of bend loss caused by the polymer coating layer for a standard singlemode fiber (SMF28) is investigated theoretically and experimentally. Bend loss for SMF28 for both the TE and TM mode is calculated separately. Normalized polarization dependent loss is proposed for the characterization of the polarization sensitivity of bend loss for different bend radii. Corresponding experimental tests are presented, which agree with the theoretical results. Both the theoretical and experimental results show that the polymer coating layer has a significant influence on the polarization dependence of bend loss.

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Solar Energy For Disaster Response Using Space Program Resources, Florida Solar Energy Center, William Young Jan 2007

Solar Energy For Disaster Response Using Space Program Resources, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Satellite pictures, solar radiation levels on the earth's surface, Global Positioning Satellites (GPS) and other space-related resources are available through the efforts of many people and organizations. Satellites' measurements of these resources can be integrated with resources on earth to assess damage from disasters and evaluate resources available to respond. Space-related resources are currently being used by the American Red Cross, the Federal Emergency Management Agency, county Emergency Managers and other organizations. The widest use is in evaluating utility resources and deploying them for repair and emergency power in response to a disaster. Today's use of state-of-the-art satellite and Geographic …

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Low Dislocation Density Gallium Nitride Templates And Their Device Applications, Jinqiao Xie Jan 2007

Low Dislocation Density Gallium Nitride Templates And Their Device Applications, Jinqiao Xie

Theses and Dissertations

The unique properties, such as large direct bandgap, excellent thermal stability, high μH × ns, of III-nitrides make them ideal candidates for both optoelectronic and high-speed electronic devices. In the past decades, great success has been achieved in commercialization of GaN based light emitting diodes (LEDs) and laser diodes (LDs). However, due to the lack of native substrates, thin films grown on sapphire or SiC substrates have high defect densities that degrade the device performance and reliability. Conventional epitaxy lateral overgrowth (ELO) can reduce dislocation densities down to ∼10-6 cm-2 in the lateral growth area, but requires ex situ photolithography …

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Modelling And Computer Simulation Of Radarscreening Using Plasma Clouds, Jonathan Blackledge Jan 2007

Modelling And Computer Simulation Of Radarscreening Using Plasma Clouds, Jonathan Blackledge

Conference papers

Following a brief introduction on the principles of screening an aerospace vehicle using a plasma, we develop models for the Impulse Response Functions (IRFs) associated with microwave (Radar) back-scattering from a strong and weakly ionized plasma screen. For a weakly ionized plasma, the conductivity is determined by the number density of electrons. We develop a model for an electron beam induced plasma that includes the effect of cascade ionization and losses due to diffusion and recombination. Qualitative results are then derived for the number density of a plasma screen over a sub-sonic aerospace vehicle and a numerical simulation considered that …

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Securitycom: A Multi-Player Game For Researching And Teaching Information Security Teams, Douglas P. Twitchell Jan 2007

Securitycom: A Multi-Player Game For Researching And Teaching Information Security Teams, Douglas P. Twitchell

Journal of Digital Forensics, Security and Law

A major portion of government and business organizations’ attempts to counteract information security threats is teams of security personnel. These teams often consist of personnel of diverse backgrounds in specific specialties such as network administration, application development, and business administration, resulting in possible conflicts between security, functionality, and availability. This paper discusses the use of games to teach and research information security teams and outlines research to design and build a simple, team-oriented, configurable, information security game. It will be used to study how information security teams work together to defend against attacks using a multi-player game, and to study …

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Table Of Contents Jan 2007

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

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Exploring Physical Intuition In Elementary Pressure Vessels, Clive L. Dym, Harry E. Williams Jan 2007

Exploring Physical Intuition In Elementary Pressure Vessels, Clive L. Dym, Harry E. Williams

All HMC Faculty Publications and Research

It is shown that displacement calculations for two classical ‘chestnuts’ – thick cylinders and spheres under internal and external pressures – present results that are not easily anticipated. Thus, such analyses provide an interesting opportunity for students (and teachers) taking elementary and advanced courses in the strength of materials to explore and perhaps enhance their physical intuition.

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