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Faculty Publications

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Articles 2371 - 2400 of 3295

Full-Text Articles in Engineering

Preliminary Modeling, Control, And Trajectory Design For Miniature Autonomous Tailsitters, Nathan B. Knoebel, Stephen R. Osborne, Deryl Snyder, Timothy W. Mclain, Randal W. Beard, Andrew Mark Eldredge Aug 2006

Preliminary Modeling, Control, And Trajectory Design For Miniature Autonomous Tailsitters, Nathan B. Knoebel, Stephen R. Osborne, Deryl Snyder, Timothy W. Mclain, Randal W. Beard, Andrew Mark Eldredge

Faculty Publications

A tailsitter UAV has unique advantages over typical fixed wing aircraft or hovercraft. This paper highlights topics of interest in our preliminary research in developing a tailsitter UAV. An aerodynamic model and quaternion-based attitude and position control scheme is presented for controlling a tailsitter through hover maneuvers, with simulation results. Desired trajectories are also developed through feedback linearization of the dynamic equations, intended for quaternion-based attitude control. Finally, a hardware platform is proposed.

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Self-Assembled Composite Nano-/Micronecklaces With Sio2 Beads In Boron Strings, Hai Ni, Xiaodong Li Jul 2006

Self-Assembled Composite Nano-/Micronecklaces With Sio2 Beads In Boron Strings, Hai Ni, Xiaodong Li

Faculty Publications

Nano-/micronecklaces with SiO2 beads in boron strings were synthesized by simply sublimating the desired powders in a sealed quartz tube at high temperature. The boron strings have a rectangular cross section with width varying from 80to1000nm while the SiO2 beads bear either spindle or spherical shape with a size ranging from 100nmto5μm. The spacing between the SiO2 beads is uniform in each boron string. Both the boron strings and the SiO2 beads are amorphous and free of defects. The supersaturated vapors of silicon and oxygen induced the SiO2 bead formation.

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Iii-Nitride Transistors With Capacitively Coupled Contacts, Grigory Simin, Z.-J. Yang, A. Koudymov, V. Adivarahan, M. Asif Khan Jul 2006

Iii-Nitride Transistors With Capacitively Coupled Contacts, Grigory Simin, Z.-J. Yang, A. Koudymov, V. Adivarahan, M. Asif Khan

Faculty Publications

AlGaN∕GaNheterostructure field-effect transistor design using capacitively coupled contacts (C3HFET) is presented. Insulated-gate [C3 metal-oxide-semiconductor HFET(C3MOSHFET)] has also been realized. The capacitively coupled source, gate, and drain of C3 device do not require annealedOhmic contacts and can be fabricated using gate alignment-free technology. For typical AlGaN∕GaNheterostructures, the equivalent contact resistance of C3 transistors is below 0.6Ωmm. In rf-control applications, the C3HFET and especially the C3MOSHFET have much higher operating rf powers as compared to HFETs.C3 design is instrumental for studying the two-dimensional electron gas transport in other wide band gap …

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Random City Generator Technical Report, Brandon Call Jul 2006

Random City Generator Technical Report, Brandon Call

Faculty Publications

The Brigham Young University (BYU) Multiple Agent Intelligent Coordination and Control (MAGICC) research lab researchs many aspects of small unmanned air vehicles (UAV). To facilitate this research, students have created a UAV simulator called Aviones. In order to increase the capability of Aviones to simulate an urban environment, the ability to draw buildings, streets and vehicles have been added. This document outlines how cities are created and how a researcher can use them in conjunction with Aviones.

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Decentralized Cooperative Aerial Surveillance Using Fixed-Wing Miniature Uavs, Randal Beard, Derek Kingston, Timothy W. Mclain, Derek Nelson Jul 2006

Decentralized Cooperative Aerial Surveillance Using Fixed-Wing Miniature Uavs, Randal Beard, Derek Kingston, Timothy W. Mclain, Derek Nelson

Faculty Publications

Numerous applications require aerial surveillance. Civilian applications include monitoring forest fires, oil fields and pipelines, and tracking wildlife. Applications to homeland security include border patrol and monitoring the perimeter of nuclear power plants. Military applications are numerous. The current approach to these applications is to use a single manned vehicle for surveillance. However, manned vehicles are typically large and expensive. In addition, hazardous environments and operator fatigue can potentially threaten the life of the pilot. Therefore, there is a critical need for automating aerial surveillance using unmanned air vehicles (UAVs). This paper gives an overview of a cooperative control strategy …

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Compact And Low Loss Silicon-On-Insulator Rib Waveguide 90° Bend, Yusheng Qian, Seunghyun Kim, Jiguo Song, Gregory P. Nordin, Jianhua Jiang Jun 2006

Compact And Low Loss Silicon-On-Insulator Rib Waveguide 90° Bend, Yusheng Qian, Seunghyun Kim, Jiguo Song, Gregory P. Nordin, Jianhua Jiang

Faculty Publications

A compact and low loss silicon-on-insulator rib waveguide 90° bend is designed and demonstrated. An interface realized by a trench filled with SU8 at the corner of a waveguide bend effectively reflects incoming light through total internal reflection (TIR). In order to accurately position the SU8-filled trench relative to the waveguide and reduce sidewall roughness of the interface, electron beam lithography (EBL) is employed while inductively coupled plasma reactive ion etching (ICP RIE) is used to achieve a vertical sidewall. The measured loss for TE polarization is 0.32 dB ± 0.02 dB/bend at a wavelength of 1.55 µm.

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Project-Based Introductory To Materials Engineering Modules On Biomaterials, Solid Oxide Fuel Cells, Non-Volatile Memory, And Fiber Reinforced Plastics, Stacy Gleixner, Elliot Douglas, Olivia Graeve Jun 2006

Project-Based Introductory To Materials Engineering Modules On Biomaterials, Solid Oxide Fuel Cells, Non-Volatile Memory, And Fiber Reinforced Plastics, Stacy Gleixner, Elliot Douglas, Olivia Graeve

Faculty Publications

PRIME Modules, Project Based Resources for Introduction to Materials Engineering, are being developed that utilize modern materials science and engineering technologies and proven education methodologies of active learning and open ended projects. The modules are designed for use in a freshmen/ sophomore level Introduction to Materials Engineering course. This course is required by most engineering programs and is an ideal place to excite students about their engineering majors and expose them to real world engineering experiences. Currently four of the classroom modules have been developed and utilized in Introduction to Materials classes. There is a non-volatile memory module where students …

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How To Weave Entrepreneurship Into Engineering Education: The Experience At San Jose State University, Minnie Patel, Anuradha Basu Jun 2006

How To Weave Entrepreneurship Into Engineering Education: The Experience At San Jose State University, Minnie Patel, Anuradha Basu

Faculty Publications

There is a growing consensus about the need for engineers and scientists to have entrepreneurial skills to be successful in their careers. However, there is a continued debate as to how best to impart these skills at the undergraduate level. It is possible to identify two routes to accomplish this objective. One route is to offer courses in engineering entrepreneurship and the other is to encourage students to participate in extracurricular activities that help to foster entrepreneurial skills. The most common approach adopted by a growing number of universities is to offer courses in entrepreneurship to engineering students. A more …

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Algan/Gan/Algan Double Heterostructure For High-Power Iii-N Field-Effect Transistors, C. Q. Chen, J. P. Zhang, V. Adivarahan, A. Koudymov, H. Fatima, Grigory Simin, J. Yang, M. Asif Khan Jun 2006

Algan/Gan/Algan Double Heterostructure For High-Power Iii-N Field-Effect Transistors, C. Q. Chen, J. P. Zhang, V. Adivarahan, A. Koudymov, H. Fatima, Grigory Simin, J. Yang, M. Asif Khan

Faculty Publications

We propose and demonstrate an AlGaN/GaN/AlGaN double heterostructure (DH) with significantly improved two-dimensional (2D) confinement for high-power III-N heterostructurefield-effect transistors(HFETs). The DH was grown directly on an AlN buffer over i-SiC substrate. It enables an excellent confinement of the 2D gas and also does not suffer from the parasitic channel formation as experienced in past designs grown over GaN buffer layers. Elimination of the GaN buffer modifies the strain distribution in the DH, enabling Al contents in the barrier region well over 30%. For the AlGaN/GaN/AlGaN DH design, the 2D electron gasmobility achieved was 1150 cm2/V s at …

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Effect Of Co On No And N2O Conversions In Nonthermal Argon Plasma, Gui-Bing Zhao, Morris D. Argyle, Maciej Radosz Jun 2006

Effect Of Co On No And N2O Conversions In Nonthermal Argon Plasma, Gui-Bing Zhao, Morris D. Argyle, Maciej Radosz

Faculty Publications

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce ⁠N2O. However, 1.01% of CO has no effect on NO conversion, but produces ⁠N2O. In general, N2O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar+⁠. Selectivity analysis of all excited states of Ar possibly contributing to NOx conversion without and with CO suggests that only Ar(3P2) contributes to NOx conversion and CO dissociation. A kinetic model of 43 …

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Sequence Of Linear Programming For Transmission Of Fine-Scalable Coded Content In Bandwidth-Limited Environments, Xiao Su, Tao Wang Jun 2006

Sequence Of Linear Programming For Transmission Of Fine-Scalable Coded Content In Bandwidth-Limited Environments, Xiao Su, Tao Wang

Faculty Publications

In this paper, we propose an optimal peer assignment algorithm on peer-to-peer networks. This algorithm is designed to maximize the quality of transmitting fine-scalable coded content by exploiting the embedding property of scalable coding. To be more realistic, we assume that the requesting peer has a delay constraint to display the content within a certain delay bound, and it also has limited incoming bandwidth. We first use a simple example to illustrate the peer assignment problem, and then formulate this problem as a linear programming problem, followed by a nonlinear programming problem. To efficiently solve the second nonlinear problem, we …

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Vector Field Path Following For Small Unmanned Aerial Vehicles, Derek R. Nelson, D. Blake Barber, Timothy W. Mclain, Randal W. Beard Jun 2006

Vector Field Path Following For Small Unmanned Aerial Vehicles, Derek R. Nelson, D. Blake Barber, Timothy W. Mclain, Randal W. Beard

Faculty Publications

This paper presents a new method for unmanned aerial vehicle path following using vector fields to represent desired ground track headings to direct the vehicle onto the desired path. The key feature of this approach is that ground track heading error and lateral following error approach zero asymptotically even in the presence of constant wind disturbances. Methods for following straight-line and circularorbit paths, as well as combinations of straight lines and arcs, are presented. Experimental results validate the effectiveness of this path following approach for small air vehicles flying in high-wind conditions.

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Vision-Based Target Localization From A Fixed-Wing Miniature Air Vehicle, Joshua D. Redding, Timothy W. Mclain, Randal W. Beard, Clark N. Taylor Jun 2006

Vision-Based Target Localization From A Fixed-Wing Miniature Air Vehicle, Joshua D. Redding, Timothy W. Mclain, Randal W. Beard, Clark N. Taylor

Faculty Publications

This paper presents a method for localizing a ground-based object when imaged from a small fixed-wing unmanned aerial vehicle (UAV). Using the pixel location of the target in an image, with measurements of UAV position and attitude, and camera pose angles, the target is localized in world coordinates. This paper presents a study of possible error sources and localization sensitivities to each source. The localization method has been implemented and experimental results are presented demonstrating the localization of a target to within 11 m of its known location.

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Combining Multiple Scoring Systems For Video Target Tracking Based On Rank-Score Function Variation, D. Frank Hsu, Damian M. Lyons, Jizhou Ai May 2006

Combining Multiple Scoring Systems For Video Target Tracking Based On Rank-Score Function Variation, D. Frank Hsu, Damian M. Lyons, Jizhou Ai

Faculty Publications

Tracking of video targets is the process of estimating the current and predicting the future state of a target from a sequence of video sensor measurements. Multitarget video tracking is complicated by the fact that targets can occlude one another and affect video feature measurements in a highly non-linear and difficult to model fashion., Tracking multiple targets that undergo repeated mutual occlusions is a challenging problem with several issues to be addressed. In this paper we propose a multisensory fusion approach to the problem of multitarget video tracking with occlusion. Each sensory cue is treated as a scoring system on …

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Digital Oxide Deposition Of Sio2 Layers For Iii-Nitride Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors, V. Adivarahan, S. Rai, N. Tipirneni, A. Koudymov, J. Yang, Grigory Simin, M. Asif Khan May 2006

Digital Oxide Deposition Of Sio2 Layers For Iii-Nitride Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors, V. Adivarahan, S. Rai, N. Tipirneni, A. Koudymov, J. Yang, Grigory Simin, M. Asif Khan

Faculty Publications

We present a digital-oxide-deposition (DOD) technique to deposit high quality SiO2dielectric layers by plasma-enhanced chemical vapor deposition using alternate pulses of silicon and oxygen precursors. The DOD procedure allows for a precise thickness control and results in extremely smooth insulating SiO2 layers. An insulating gate AlGaN∕GaNheterostructurefield-effect transistor(HFET) with 8nm thick DOD SiO2dielectric layer had a threshold voltage of −6V (only 1V higher than that of regular HFET), very low threshold voltage dispersion, and output continuous wave rf power of 15W∕mm at 55V drain bias.

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An Xyz Micromanipulator With Three Translational Degrees Of Freedom, Kimberly A. Jensen, Craig P. Lusk, Larry L. Howell May 2006

An Xyz Micromanipulator With Three Translational Degrees Of Freedom, Kimberly A. Jensen, Craig P. Lusk, Larry L. Howell

Faculty Publications

This paper introduces a three degree of freedom XYZ Micromanipulator (XYZM) that is fabricated in the x-y plane and positions components in the x, y, and z directions using three independent linear inputs. The mechanism positions components on a platform using three legs, each composed of a slider mechanism and a parallelogram mechanism.

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Compact Integrated Depolarizer For Interferometric Fiber Optic Gyroscopes, Lixia Li, Jaime Cardenas, Jianhua Jiang, Gregory P. Nordin May 2006

Compact Integrated Depolarizer For Interferometric Fiber Optic Gyroscopes, Lixia Li, Jaime Cardenas, Jianhua Jiang, Gregory P. Nordin

Faculty Publications

We propose an integrated waveguide depolarizer for use in interferometric fiber optic gyroscopes (IFOGs) with single-mode fiber coils. The integrated waveguide depolarizer is based on a Mach-Zender interferometer with polarizing beamsplitters. A waveguide polarizing beamsplitter is designed using multiple air trench structures oriented at the Brewster angle. We also analyze the effect of component imperfections on the degree of polarization achievable with an integrated waveguide depolarizer.

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Design Of Compact Polymer Mach-Zender Interferometer And Ring Resonator With Air Trench Structures, Seunghyun Kim, Jianhua Jiang, Gregory P. Nordin May 2006

Design Of Compact Polymer Mach-Zender Interferometer And Ring Resonator With Air Trench Structures, Seunghyun Kim, Jianhua Jiang, Gregory P. Nordin

Faculty Publications

We discuss the design of a compact ring resonator (RR) and Mach-Zehnder interferometer (MZI) in a low-refractive-index-contrast waveguide material system through the use of air trenches. A narrow air trench at the intersection of one input and two output waveguides can function as a high-efficiency splitter, while wider air trenches operate as waveguide bends. We first discuss the design of individual splitters and bends and then show how they can be used to realize a compact MZI and RR. The RR has a footprint of only 70 X 100 um, and its optical efficiency at the drop wavelengths is 86%. …

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Multiple Masks-Based Pixel Comparison Steganalysis Method For Mobile Imaging, Sos S. Agaian, Gilbert L. Peterson, Benjamin M. Rodriguez May 2006

Multiple Masks-Based Pixel Comparison Steganalysis Method For Mobile Imaging, Sos S. Agaian, Gilbert L. Peterson, Benjamin M. Rodriguez

Faculty Publications

No abstract provided.

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Erratum: “Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal” [Appl. Phys. Lett.87, 182104 (2005)], B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal Apr 2006

Erratum: “Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal” [Appl. Phys. Lett.87, 182104 (2005)], B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal

Faculty Publications

No abstract provided.

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Combinatorial Fusion Criteria For Real-Time Tracking, D. Frank Hsu, Damian M. Lyons, Jizhou Ai Apr 2006

Combinatorial Fusion Criteria For Real-Time Tracking, D. Frank Hsu, Damian M. Lyons, Jizhou Ai

Faculty Publications

We address the problem of automated video tracking of targets when targets undergo multiple mutual occlusions. Our approach is based on the idea that as targets are occluded, selection of feature subsets and combinations of those features are effective in identifying the target and improving tracking performance. We use Combinatorial Fusion Analysis to develop a metric to select which subset of features will produce the most accurate tracking. In particular we show that the combination of a pair of features A and B will improve the accuracy only if (a) A and B have relative high performance, and (b) A …

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Feature Selection For Real-Time Tracking, D. Frank Hsu, Damian M. Lyons, Jizhou Ai Apr 2006

Feature Selection For Real-Time Tracking, D. Frank Hsu, Damian M. Lyons, Jizhou Ai

Faculty Publications

We address the problem of selecting features to improve automated video tracking of targets that undergo multiple mutual occlusions. As targets are occluded, different feature subsets and combinations of those features are effective in identifying the target and improving tracking performance. We use Combinatorial Fusion Analysis to develop a metric to dynamically select which subset of features will produce the most accurate tracking. In particular we show that the combination of a pair of features A and B will improve the accuracy only if (a) A and B have relative high performance, and (b) A and B are diverse. We …

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Power Anomaly Effects And Costs In Low-Voltage Mobile Power Systems, Shengyi Liu, Charles H. Singer, Roger A. Dougal Apr 2006

Power Anomaly Effects And Costs In Low-Voltage Mobile Power Systems, Shengyi Liu, Charles H. Singer, Roger A. Dougal

Faculty Publications

Electric power anomalies or disturbances can disrupt the normal operation of equipment, accelerate aging, or even cause outright failures thus resulting in increased costs of maintenance and reduced system reliability. Past research on the effects caused by power anomalies has been mostly focused on industrial, commercial, or residential systems, or on power distribution equipment. A literature survey reveals that there is no comprehensive review related to low-voltage (LV) power systems and utilization equipment applicable to military combat vehicles, such as aircraft and ships. This paper summarizes the results of a new literature survey that focused on the causes, effects, and …

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Jamming Sensor Networks: Attack And Defense Strategies, Wenyuan Xu, Wade Trappe, Yanyong Zhang Apr 2006

Jamming Sensor Networks: Attack And Defense Strategies, Wenyuan Xu, Wade Trappe, Yanyong Zhang

Faculty Publications

Wireless sensor networks are built upon a shared medium that makes it easy for adversaries to conduct radio interference, or jamming, attacks that effectively cause a denial of service of either transmission or reception functionalities. These attacks can easily be accomplished by an adversary by either bypassing MAC-layer protocols or emitting a radio signal targeted at jamming a particular channel. In this article we survey different jamming attacks that may be employed against a sensor network. In order to cope with the problem of jamming, we discuss a two-phase strategy involving the diagnosis of the attack, followed by a suitable …

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A Reconfigurable Distributed Computing Fabric Exploiting Multilevel Parallelism, Charles L. Cathey, Jason D. Bakos, Duncan A. Buell Apr 2006

A Reconfigurable Distributed Computing Fabric Exploiting Multilevel Parallelism, Charles L. Cathey, Jason D. Bakos, Duncan A. Buell

Faculty Publications

This paper presents a novel reconfigurable data flow processing architecture that promises high performance by explicitly targeting both fine- and course-grained parallelism. This architecture is based on multiple FPGAs organized in a scalable direct network that is substantially more interconnect-efficient than currently used crossbar technology. In addition, we discuss several ancillary issues and propose solutions required to support this architecture and achieve maximal performance for general-purpose applications; these include supporting IP, mapping techniques, and routing policies that enable greater flexibility for architectural evolution and code portability.

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Forest Fire Monitoring Using Multiple Unmanned Air Vehicles, Timothy Mclain, Randal W. Beard, Ryan S. Holt, Joseph W. Egbert, Justin M. Bradley, Clark N. Taylor Apr 2006

Forest Fire Monitoring Using Multiple Unmanned Air Vehicles, Timothy Mclain, Randal W. Beard, Ryan S. Holt, Joseph W. Egbert, Justin M. Bradley, Clark N. Taylor

Faculty Publications

The ability to gather and process information on the condition of forest fires is essential to fighting the fires in a cost-effective, safe, and efficient manner. While high-altitude, long-endurance (HALE) unmanned air vehicles (UAVs) are currently used for fire surveillance; they are an expensive and scarce resource. As a proposed alternative, low-altitude, short-endurance (LASE) UAVs offer lower costs, quicker response times, and high- resolution information. In recent years, advances in solid-state sensor and autopilot technology have made LASE UAVs a feasible alternative. This paper overviews a current research project conducted by Brigham Young University and NASA Ames. In the project, …

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Managing The Integration Of Space And Information Operations, Daniel F. Gottrich, Michael R. Grimaila Apr 2006

Managing The Integration Of Space And Information Operations, Daniel F. Gottrich, Michael R. Grimaila

Faculty Publications

No abstract provided.

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Contingency Planning And An Air Force Space Command Information System, Kaylin Freedman, Michael R. Grimaila Apr 2006

Contingency Planning And An Air Force Space Command Information System, Kaylin Freedman, Michael R. Grimaila

Faculty Publications

No abstract provided.

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Effect Of Co On No And N2o Conversions In Nonthermal Argon Plasma, Morris D. Argyle, Gui-Bing Zhao, Maciej Radosz Mar 2006

Effect Of Co On No And N2o Conversions In Nonthermal Argon Plasma, Morris D. Argyle, Gui-Bing Zhao, Maciej Radosz

Faculty Publications

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce N2O. However, 1.01% of CO has no effect on NO conversion, but produces N2O. In general, N2O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar+. Selectivity analysis of all excited states of Ar possibly contributing to NOX conversion without and with CO suggests that only AR(3P2) contributes to NOX conversion and CO dissociation. A kinetic model of 43 reactions is required to model NO Conversion or N2O conversion in Ar without CO, …

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Convergence Of Ipsec In Presence Of Resets, Chin-Tser Huang, Mohamed G. Gouda, E.N. Elnozahy Mar 2006

Convergence Of Ipsec In Presence Of Resets, Chin-Tser Huang, Mohamed G. Gouda, E.N. Elnozahy

Faculty Publications

IPsec is the current security standard for the Internet Protocol IP. According to this standard, a selected computer pair (p, q) in the Internet can be designated a “security association”. This designation guarantees that all sent IP messages whose original source is computer p and whose ultimate destination is computer q cannot be replayed in the future (by an adversary between p and q) and still be received by computer q as fresh messages from p. This guarantee is provided by adding increasing sequence numbers to all IP messages sent from p to q. Thus, p needs to always remember …

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