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- Deposition (3)
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- Antenna array mutual coupling (1)
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Articles 1 - 30 of 37
Full-Text Articles in Engineering
Estimating Tmr Reliability On Fpgas Using Markov Models, Daniel Mcmurtrey, Keith S. Morgan, Brian Pratt, Michael J. Wirthlin
Estimating Tmr Reliability On Fpgas Using Markov Models, Daniel Mcmurtrey, Keith S. Morgan, Brian Pratt, Michael J. Wirthlin
Faculty Publications
This paper summarizes several reliability models for modeling FPGA reliability using Markov models.
Decentralized Perimeter Surveillance Using A Team Of Uavs, Randal Beard, David Casbeer, Derek Kingston
Decentralized Perimeter Surveillance Using A Team Of Uavs, Randal Beard, David Casbeer, Derek Kingston
Faculty Publications
Sponsorship: NASA, AFOSR. This paper develops a distributed algorithm to maintain a current estimate of the state of the perimeter using a team of UAVs. Using notions of consensus, an algorithm is developed and shown to distribute a UAV team uniformly around the perimeter.
A C-Band Scatterometer Simultaneous Wind/Rain Retrieval Method, David G. Long, Congling Nie
A C-Band Scatterometer Simultaneous Wind/Rain Retrieval Method, David G. Long, Congling Nie
Faculty Publications
Using collocated ERS scatterometer (ESCAT), Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), and European Centre for Medium-Range Weather Forecasts (ECMWF) data, the effects of rain on ESCAT wind-only retrieval are evaluated. Additional scattering from rain causes estimated wind speeds to appear higher than expected. Selected directions of the rain-corrupted wind vectors are biased toward along-track directions under conditions of heavy rain, which is regardless of the true wind direction. Rain becomes more significant for data acquired at a high incidence angle. To compensate for rain-induced backscatter, a simultaneous wind/rain retrieval (SWRR) method, which simultaneously retrieves wind velocity and surface …
A Low-Cost Open-Hardware Wideband Multiple-Input-Multiple-Output (Mimo) Wireless Channel Sounder, Michael A. Jensen, Jon W. Wallace, B. T. Maharaj, Louis P. Linde
A Low-Cost Open-Hardware Wideband Multiple-Input-Multiple-Output (Mimo) Wireless Channel Sounder, Michael A. Jensen, Jon W. Wallace, B. T. Maharaj, Louis P. Linde
Faculty Publications
Due to the complexity of multiple-input-multiple- output (MIMO) wireless channels, direct measurement is the main viable option for accurate characterization. Details on a new low-cost wideband channel sounder are presented, which was mainly constructed from conventional instruments and components. This switched architecture system is similar to commercial channel sounders and has modest cost (< US$ 50000). The sounder operates in the 2- to 8-GHz range with up to 100 MHz of instantaneous bandwidth and supports eight transmitters and receivers, which are sufficient to support the development and assessment of current and future MIMO wireless systems. In this "open-hardware" project, the hardware design and software components are openly available to other researchers interested in developing or enhancing the MIMO measurement capability. The actual systems built at the University of Pretoria, Pretoria, South Africa, and Brigham Young University, Provo, UT, are presented, as are some example studies.
Optimal Estimation Of Calibration Parameters In Polarimetric Microwave Radiometers, David G. Long, Derek Hudson
Optimal Estimation Of Calibration Parameters In Polarimetric Microwave Radiometers, David G. Long, Derek Hudson
Faculty Publications
Methods for internal calibration of a certain class of microwave polarimetric radiometers are presented by Piepmeier. In that work, the calibration parameters are estimated algebraically. We demonstrate that Bayesian estimation decreases the root-mean-square error of the estimates by a factor of two. This improvement is obtained by using knowledge of the noise structure of the measurements and by utilizing all of the information provided by the measurements. Drawbacks are the increased complexity of the method and an increase in computation. We also extend the method to estimate several hardware component parameters of interest in system calibration.
Reduced-Feedback Linear Precoding With Stable Performance For The Time-Varying Mimo Broadcast Channel, Michael A. Jensen, Adam L. Anderson, James R. Zeidler
Reduced-Feedback Linear Precoding With Stable Performance For The Time-Varying Mimo Broadcast Channel, Michael A. Jensen, Adam L. Anderson, James R. Zeidler
Faculty Publications
This work explores the performance of a multiple-input multiple-output broadcast channel where both the transmitter and receivers have outdated channel knowledge due to node motion or other time-variations in the communication channel. A performance analysis based on measured channel responses reveals significant throughput degradation for optimal linear and nonlinear precoding strategies unless the channel state information (CSI) is frequently fed back to the transmitter. The paper then develops a linear beamforming precoding strategy based on channel distribution information in the form of a full spatial correlation matrix for each user. This algorithm is shown to provide highly stable communication, with …
Theory And Application Of Motion Compensation For Lfm-Cw Sar, David G. Long, Evan C. Zaugg
Theory And Application Of Motion Compensation For Lfm-Cw Sar, David G. Long, Evan C. Zaugg
Faculty Publications
Small low-cost high-resolution synthetic aperture radar (SAR) systems are made possible by using a linear frequency-modulated continuous-wave (LFM-CW) signal. SAR processing assumes that the sensor is moving in a straight line at a constant speed, but in actuality, an unmanned aerial vehicle (UAV) or airplane will often significantly deviate from this ideal. This nonideal motion can seriously degrade the SAR image quality. In a continuous-wave system, this motion happens during the radar pulse, which means that existing motion compensation techniques that approximate the position as constant over a pulse are limited for LFM-CW SAR. Small aircraft and UAVs are particularly …
Estimation Of Hurricane Winds From Seawinds At Ultrahigh Resolution, David G. Long, Brent A. Williams
Estimation Of Hurricane Winds From Seawinds At Ultrahigh Resolution, David G. Long, Brent A. Williams
Faculty Publications
Although the SeaWinds scatterometer was not specifically designed to observe tropical cyclones, new high-resolution wind products resolve much of the horizontal structure of these storms. However, these higher resolution products (2.5 km) are inherently noisier than the standard 25-km near-surface wind products. These noise levels combined with rain contamination complicate high-resolution wind estimation-particularly in tropical cyclones. Fortunately, tropical cyclones have structures that can be exploited by using a wind field model. This paper develops a new procedure for hurricane wind field estimation from the SeaWinds instrument at ultrahigh resolution. A simplified hurricane model is developed to provide prior information to …
Evaluating Three-Dimensional Effects On The Behavior Of Compliant Bistable Micromechanisms, Brian B. Cherry, Larry L. Howell, Brian D. Jensen
Evaluating Three-Dimensional Effects On The Behavior Of Compliant Bistable Micromechanisms, Brian B. Cherry, Larry L. Howell, Brian D. Jensen
Faculty Publications
Fully compliant bistable micromechanisms (FCBMs) have potential use in numerous applications, including switches, relays, shutters, and low-power sensing arrays. Two-dimensional finite element models for these FCBMs have been used in device analysis and design, and provided an adequate match to preliminary experimental data. However, with more extensive experimentation over a large range of designs, some results proved to be radically different than predicted, with trends not consistent with effects such as stiction or electrostatic forces. Two different types of behavior, Behavior 1 and Behavior 2, are observed and explained, only one of which is predicted by 2-D models. This paper …
Windsat Passive Microwave Polarimetric Signatures Of The Greenland Ice Sheet, David G. Long, Li Li, Peter Gaiser, Mary R. Albert, Elizabeth M. Twarog
Windsat Passive Microwave Polarimetric Signatures Of The Greenland Ice Sheet, David G. Long, Li Li, Peter Gaiser, Mary R. Albert, Elizabeth M. Twarog
Faculty Publications
WindSat has systematically collected the first global fully polarimetric passive microwave data over both land and ocean. As the first spaceborne polarimetric microwave radiometer, it was designed to measure ocean surface wind speed and direction by including the third and fourth Stokes parameters, which are mostly related to the asymmetric structures of the ocean surface roughness. Although designed for wind vector retrieval, WindSat data are also collected over land and ice, and this new data has revealed, for the first time, significant land signals in the third and fourth Stokes parameter channels, particularly over Greenland and the Antarctic ice sheets. …
Ultracompact Awg Using Air-Trench Bends With Perfluorocyclobutyl Polymer Waveguides, Seunghyun Kim, Gregory P. Nordin, John Ballato, Yongbin Lin, Nazli Rahmanian, Dennis W. Smith, Chris Topping
Ultracompact Awg Using Air-Trench Bends With Perfluorocyclobutyl Polymer Waveguides, Seunghyun Kim, Gregory P. Nordin, John Ballato, Yongbin Lin, Nazli Rahmanian, Dennis W. Smith, Chris Topping
Faculty Publications
Using air-trench bends, an ultracompact 8 8 arrayed waveguide grating (AWG) demultiplexer (200-GHz channel spacing) for wavelength-division multiplexing (WDM) has been designed and fabricated with perfluorocyclobutyl (PFCB) core and clad co-polymers on a polyimide substrate. Compared to a conventional AWG in the same material system, the air-trench bend AWG shrinks the required chip area by a factor of 20. The decreased size is a factor in reducing the measured thermal shift to -0.012 nm/ C and decreasing the polarization-dependent wavelength shift to 1.3 nm.
In-Plane Photonic Transduction Of Silicon-On-Insulator Microcantilevers, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Jaime Cardenas
In-Plane Photonic Transduction Of Silicon-On-Insulator Microcantilevers, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Jaime Cardenas
Faculty Publications
We demonstrate an in-plane photonic transduction method for microcantilevers, which have been widely investigated for sensor applications. In our approach the microcantilever is etched to form a single mode rib waveguide. Light propagates down the microcantilever and crosses a small gap at the free end of the microcantilever, some of which is captured by an asymmetrical multimode waveguide that terminates in a Y-branch. The Y-branch outputs are used to form a differential signal that is monotonically dependent on microcantilever deflection. The measured differential signal matches simulation when microcantilever rotation is properly accounted for. The measured differential signal sensitivity is 1.4 …
Aerobatic Maneuvering Of Miniature Air Vehicles Using Attitude Trajectories, James K. Hall, Timothy W. Mclain
Aerobatic Maneuvering Of Miniature Air Vehicles Using Attitude Trajectories, James K. Hall, Timothy W. Mclain
Faculty Publications
We develop aerobatic maneuvering for miniature air vehicles (MAVs) using time-parameterized attitude trajectory generation and an associated attitude tracking control law. We develop two methodologies, polynomial or trigonometric, for creating smooth functions that specify pitch and roll angle trajectories. For both approaches, the functions are constrained by the maneuver boundary conditions for aircraft position and velocity. We develop a feedback control law to regulate aircraft orientation throughout the maneuvers. The performance of our trajectory generation algorithm and our attitude tracking control law is demonstrated through simulated and actual flight tests of aerobatic maneuvers.
Modeling Phase Transitions Of Nanoemulsion For Ultrasonic Gene Delivery, Ghaleb A. Husseini, William G. Pitt, Ram Singh
Modeling Phase Transitions Of Nanoemulsion For Ultrasonic Gene Delivery, Ghaleb A. Husseini, William G. Pitt, Ram Singh
Faculty Publications
A computer model was written that simulates the transformation of a nanoemulsion droplet to a gas bubble by the application of ultrasound. Experimentally such a technique could be used to enhance non-viral gene transfection beyond the boundary of the endothelial lining of the circulatory system, particularly in tumors exhibiting enhanced permeation and retention of nanoparticles.
A Satisficing Approach To Aircraft Conflict Resolution, Wynn C. Stirling, James K. Archibald, Nicholas A. Jepsen, Richard L. Frost, Jared C. Hill
A Satisficing Approach To Aircraft Conflict Resolution, Wynn C. Stirling, James K. Archibald, Nicholas A. Jepsen, Richard L. Frost, Jared C. Hill
Faculty Publications
Future generations of air traffic management systems may give appropriately equipped aircraft the freedom to change flight paths in real time. This would require a conflict avoidance and resolution scheme that is both decentralized and cooperative. We describe a multiagent solution to aircraft conflict resolution based on satisficing game theory. A key feature of the theory is that satisficing decision makers form their preferences by taking into consideration the preferences of others, unlike conventional game theory that models agents that maximize self-interest metrics. This makes possible situational altruism, a sophisticated form of unselfish behavior in which the preferences of another …
Efficiencies And System Temperature For A Beamforming Array, Karl F. Warnick, Brian D. Jeffs
Efficiencies And System Temperature For A Beamforming Array, Karl F. Warnick, Brian D. Jeffs
Faculty Publications
For an active beamforming array, standard definitions for efficiencies and system temperature are not available. We use noise considerations to generalize the single-antenna conventions for aperture efficiency, spillover efficiency, radiation efficiency, and system temperature to arrays. The treatment leads to a new noise matching efficiency that quantifies the effect of mutual coupling on amplifier noise. Numerical results for a phased array feed indicate that the noise increase caused by mutual coupling can be significant.
Adaptive Quaternion Control Of A Miniature Tailsitter Uav, Nathan B. Knoebel, Timothy W. Mclain
Adaptive Quaternion Control Of A Miniature Tailsitter Uav, Nathan B. Knoebel, Timothy W. Mclain
Faculty Publications
The miniature tailsitter is a unique aircraft with inherent advantages over typical unmanned aerial vehicles. With the capabilities of both hover and level flight, these small, portable systems can produce efficient maneuvers for enhanced surveillance and autonomy with little threat to surroundings and the system itself. Such vehicles create control challenges due to the two different flight regimes. These challenges are addressed with a computationally efficient adaptive quaternion control algorithm. A backstepping method for model cancellation and consistent tracking of reference model attitude dynamics is derived. This is used in conjunction with a regularized data-weighting recursive least-squares algorithm for the …
Minimizing The Noise Penalty Due To Mutual Coupling For A Receiving Array, Karl F. Warnick, Leonid Belostotski, Peter Russer
Minimizing The Noise Penalty Due To Mutual Coupling For A Receiving Array, Karl F. Warnick, Leonid Belostotski, Peter Russer
Faculty Publications
For phased array receivers, mutual coupling leads to beam-dependent effective impedances at array element ports. Front end amplifiers can be matched for optimal noise performance for one beam steering direction, but noise performance becomes poor at other steering directions. We analyze this noise penalty in terms of beam equivalent noise temperature for various amplifier noise matching conditions, and develop a new matching condition that minimizes the average beam equivalent receiver noise temperature over multiple beams. For non-beamforming applications such as MIMO communications, we show that noise performance for coupled arrays can be quantified using the spectrum of an available receiver …
Nano-Polymeric Carrier Influences Ultrasonic Drug Delivery To Tumors, Odgerel Badamjav, Ghaleb A. Husseini, Peter Jones, William G. Pitt, Beverly L. Roeder
Nano-Polymeric Carrier Influences Ultrasonic Drug Delivery To Tumors, Odgerel Badamjav, Ghaleb A. Husseini, Peter Jones, William G. Pitt, Beverly L. Roeder
Faculty Publications
Our overall research goal is to alleviate the severe side effects of chemotherapy while enhancing the effectiveness of the treatment by localizing the delivery of anti-cancer drugs to the cancer tissue only. To this end we are synthesizing ultrasonically-activated delivery systems that can control drug delivery in space and time. Ultrasound (US) is non-invasive (no surgery required) and can be focused on the specific tissue to be treated. Our past research has developed a nano-sized polymeric drug carrier that sequesters the therapeutic drug, such as Doxorubicin (Dox), within the carrier and releases the drug upon insonation by ultrasound. This drug-containing …
Quadrotor Dynamics And Control Rev 0.1, Randal Beard
Quadrotor Dynamics And Control Rev 0.1, Randal Beard
Faculty Publications
These notes outline quadrotor dynamics, state estimation, and control using a camera as the primary sensor.
Near Optimal Common Detection Techniques For Shaped Offset Qpsk And Feher's Qpsk, Tom Nelson, Michael D. Rice, Erik Perrins
Near Optimal Common Detection Techniques For Shaped Offset Qpsk And Feher's Qpsk, Tom Nelson, Michael D. Rice, Erik Perrins
Faculty Publications
This paper compares three candidate detection techniques for shaped offset QPSK (SOQPSK-TG) and Feher's QPSK (FQPSK-JR) modulations which are embodied as fully interoperable modulations in the Interrange Instrumentation Group standard IRIG-106. The techniques are based on a common trellis-coded modulation representation and a common continuous phase modulation (CPM) representation for these two modulations. In addition the pulse amplitude modulation (PAM) decomposition of the common CPM representation is developed. All three techniques achieve near-optimal bit error rate performance. The PAM-based detector offers the best performance-complexity trade-off.
Compact Waveguide Splitter Networks, Seunghyun Kim, Gregory P. Nordin, Weisheng Hu, Yusheng Qian, Jiguo Song
Compact Waveguide Splitter Networks, Seunghyun Kim, Gregory P. Nordin, Weisheng Hu, Yusheng Qian, Jiguo Song
Faculty Publications
We demonstrate compact waveguide splitter networks in siliconon-insulator (SOI) rib waveguides using trench-based splitters (TBSs) and bends (TBBs). Rather than a 90° geometry, we use 105° TBSs to facilitate reliable fabrication of high aspect ratio trenches suitable for 50/50 splitting when filled with SU8. Three dimensional (3D) finite difference time domain (FDTD) simulation is used for splitter and bend design. Measured TBB and TBS optical efficiencies are 84% and 68%, respectively. Compact 105° 1 x 4, 1 x 8, and 1 x 32 trench-based splitter networks (TBSNs) are demonstrated. The measured total optical loss of the 1 x 32 TBSN …
Capacity Of The Continuous-Space Electromagnetic Channel, Michael A. Jensen, Jon W. Wallace
Capacity Of The Continuous-Space Electromagnetic Channel, Michael A. Jensen, Jon W. Wallace
Faculty Publications
Constructing the capacity bound of a multiple-input multiple-output wireless system is often performed by assuming specified antenna configurations and a propagation environment and determining the signaling strategy which maximizes throughput. This paper extends this approach to further determine the optimal antenna characteristics which maximize the capacity for the propagation scenario, with the resulting capacity bound representing the ultimate maximum achievable value if optimal antenna design and signaling are used. In this approach, the spatially-continuous transmit currents and receive fields are represented using eigenfunctions of appropriate operators. It is shown that, except under certain conditions where array supergain solutions emerge, the …
Experimental Analysis Of A Wideband Adaptive-Mimo Antenna, Michael A. Jensen
Experimental Analysis Of A Wideband Adaptive-Mimo Antenna, Michael A. Jensen
Faculty Publications
An experimental measurement campaign to investigate the wideband performance of an adaptive multiple-input multiple-output (AdaM) antenna consisting of two active and six parasitic antenna elements. The measurements are conducted over a 30 MHz bandwidth at a center frequency of 2.55 GHz and in a variety of locations in an indoor environment. The system uses a traditional two-element array at the transmitter and either a two-element traditional array or the AdaM antenna at the receiver. The results show that compared to the traditional array, the AdaM receive antenna can achieve the same throughput with an average power reduction of 2.7 dB …
Observations Of Piezoresistivity For Polysilicon In Bending That Are Unexplained By Linear Models, Tyler L. Waterfall, Gary K. Johns, Robert K. Messenger, Brian D. Jensen, Timothy W. Mclain, Larry L. Howell
Observations Of Piezoresistivity For Polysilicon In Bending That Are Unexplained By Linear Models, Tyler L. Waterfall, Gary K. Johns, Robert K. Messenger, Brian D. Jensen, Timothy W. Mclain, Larry L. Howell
Faculty Publications
Compliant piezoresistive MEMS sensors exhibit great promise for improved on-chip sensing. As compliant sensors may experience complex loads, their design and implementation require a greater understanding of the piezoresistive effect of polysilicon in bending and combined loads. This paper presents experimental results showing the piezoresistive effect for these complex loads. Several n-type polysilicon test structures, fabricated in MUMPs and SUMMiT processes, were tested. Results show that, while tensile stresses cause a linear decrease in resistance, bending stresses induce a nonlinear rise in resistance, contrary to the effect predicted by linear models. In addition, tensile, compressive, and bending loads combine in …
A Model For Predicting The Piezoresistive Effect In Microflexures Experiencing Bending And Tension Loads, Gary K. Johns, Larry L. Howell, Brian D. Jensen, Timothy W. Mclain
A Model For Predicting The Piezoresistive Effect In Microflexures Experiencing Bending And Tension Loads, Gary K. Johns, Larry L. Howell, Brian D. Jensen, Timothy W. Mclain
Faculty Publications
This paper proposes a model for predicting the piezoresistive effect in microflexures experiencing bending stresses. Linear models have long existed for describing piezoresistivity for members in pure tension and compression. However, extensions of linear models to more complex loading conditions do not match with experimental results. A second-order model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. A reduced form of the general second-order model is presented for thin flexures in bending. A three-step approach is used to determine the piezoresistive coefficients for this reduced-form model. The approach is demonstrated for two sets of …
Electromagnetic Considerations For Communicating On Correlated Mimo Channels With Covariance Information, Michael A. Jensen, Jon W. Wallace
Electromagnetic Considerations For Communicating On Correlated Mimo Channels With Covariance Information, Michael A. Jensen, Jon W. Wallace
Faculty Publications
Previous results for correlated block-fading MIMO channels with covariance information indicate guaranteed capacity growth with additional transmit elements and that in rapidly fading channels, vanishing element spacing maximizes capacity. However, because prior analysis neglects antenna electromagnetic coupling, the observations are not necessarily valid for small inter-element spacing. This work applies radiated power considerations to the analysis to demonstrate that additional elements do not always increase capacity and that vanishing element spacing is not optimal. An effective gain metric is introduced that quantifies the performance increase with additional transmitters in the presence of transmit correlation and mutual coupling. Performance simulations using …
Stokes Antenna Temperatures, David G. Long, Jeffrey R. Piepmeier, Eni G. Njoku
Stokes Antenna Temperatures, David G. Long, Jeffrey R. Piepmeier, Eni G. Njoku
Faculty Publications
The growing importance of polarimetric radiometers has led to the need for a detailed theory for Stokes antenna temperatures. In this paper, we provide a full Stokes vector formulation of an antenna temperature that accounts for the entire antenna pattern, which includes polarization mixing in the main-beam and sidelobe effects. To derive the Stokes antenna temperatures, we follow the conventional methods in the Earth remote sensing literature while relying on a coherency algebra approach from radio astronomy. Connections and parallels to the conventional approaches are noted along the way. We also introduce generalizations of beam efficiency and cross polarization for …
Mpsa Effects On Copper Electrodeposition Investigated By Molecular Dynamics Simulations, John N. Harb, Richard L. Rowley, Dean R. Wheeler, Clint G. Guymon
Mpsa Effects On Copper Electrodeposition Investigated By Molecular Dynamics Simulations, John N. Harb, Richard L. Rowley, Dean R. Wheeler, Clint G. Guymon
Faculty Publications
In superconformal filling of copper-chip interconnects, organic additives are used to fill high-aspect-ratio trenches or vias from the bottom up. In this study we report on the development of intermolecular potentials and use molecular dynamics simulation.
Mpsa Effects On Copper Electrodeposition Investigated By Molecular Dynamics Simulations, Clint G. Guymon, John N. Harb, Richard L. Rowley, Dean R. Wheeler
Mpsa Effects On Copper Electrodeposition Investigated By Molecular Dynamics Simulations, Clint G. Guymon, John N. Harb, Richard L. Rowley, Dean R. Wheeler
Faculty Publications
In superconformal filling of copper-chip interconnects, organic additives are used to fill high-aspect-ratio trenches or vias from the bottom up. In this study we report on the development of intermolecular potentials and use molecular dynamics simulations to provide insight into the molecular function of an organic additive (3-mercaptopropanesulfonic acid or MPSA) important in superconformal electrodeposition. We also investigate how the presence of sodium chloride affects the surface adsorption and surface action of MPSA as well as the charge distribution in the system. We find that NaCl addition decreases the adsorption strength of MPSA at a simulated copper surface and attenuates …