Engineering Commons^™

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.

Three-Dimensional Direct Numerical Simulation Of Soot Formation And Transport In A Temporally Evolving Nonpremixed Ethylene Jet Flame, David O. Lignell, Jacqueline H. Chen, Philip J. Smith

Faculty Publications

Three-dimensional direct numerical simulation of soot formation with complex chemistry is presented. The simulation consists of a temporally evolving, planar, nonpremixed ethylene jet flame with a validated, 19-species reduced mechanism. A four-step, three-moment, semiempirical soot model is employed. Previous two-dimensional decaying turbulence simulations have shown the importance of multidimensional flame dynamical effects on soot concentration [D.O. Lignell, J.H. Chen, P.J. Smith, T. Lu, C.K. Law, Combust. Flame 151 (1–2) (2007) 2–28]. It was shown that flame curvature strongly impacts the diffusive motion of the flame relative to soot (which is essentially convected with the flow), resulting in soot being differentially …

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.

The 5 Ghz Airport Surface Area Channel: Part Ii, Measurement And Modeling Results For Small Airports, Indranil Sen, David W. Matolak

Faculty Publications

This paper describes results from a channel measurement campaign performed at several small airports in the U.S. in the 5-GHz band. This paper is a companion to another paper, which describes channel models for large airports. We classify the small airport surface channel into three propagation regions based upon different delay dispersion conditions. The channel characteristics of these regions in the delay and frequency domains are discussed with examples. We provide empirical stochastic channel models (of different bandwidths) to accurately represent the channel on the airport surface area for all propagation regions. The models are provided in the form of …

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 …

Engineering Project Laboratory Modules For An Introduction To Materials Course, Stacy Gleixner, Elliot Douglas, Olivia Graeve

Faculty Publications

The final results of curriculum development under an NSF, CCLI-EMD sponsored project, “Development of Project-Based Introductory to Materials Engineering Modules” (DUE # #0341633) is discussed. A multi-university team of faculty developed five lecture and three laboratory modules for use in Introductory to Materials courses. This course is required by most engineering programs in the U.S., with an annual enrollment of 50,000 students.1 This freshman/ sophomore class is an ideal place to excite students about their engineering majors and expose them to real world engineering problems. PRIME Modules, Project Based Resources for Introduction to Materials Engineering, utilize modern materials science and …

Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li

Faculty Publications

Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, P_H2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium P_H2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that P_H2 (T) …

Vehicle-Vehicle Channel Models For The 5 Ghz Band, Indranil Sen, David W. Matolak

Faculty Publications

In this paper, we describe the results of a channel measurement and modeling campaign for the vehicle-to-vehicle (V2V) channel in the 5-GHz band. We describe measurements and results for delay spread, amplitude statistics, and correlations for multiple V2V environments. We also discuss considerations used in developing statistical channel models for these environments and provide some sample results. Several statistical channel models are presented, and using simulation results, we elucidate tradeoffs between model implementation complexity and fidelity. The channel models presented should be useful for system designers in future V2V communication systems.

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.

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 …

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 …

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 …

Channel Modeling For Vehicle-To-Vehicle Communications, David W. Matolak

Faculty Publications

Physical layer channel modeling is critical for design and performance evaluation at multiple layers of the communications protocol stack. In this article we describe and provide results for modeling vehicle-to-vehicle (V2V) wireless channels. V2V settings produce some unique conditions, and due to these conditions, V2V channels often exhibit greater dynamics than many conventional channels and, in addition, can also exhibit more severe fading. Thus, new channel models are needed to characterize this setting in order to evaluate contending transmission schemes and aid in V2V communication system design. A brief review of key statistical channel parameters is provided. Then both analytical …

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.

Novel Wideband Directional Dipole Antenna On A Mushroom Like Ebg Structure, Mohammed Z. Azad, Mohammod Ali

Faculty Publications

A new method to design thin wideband directional dipole antennas on electromagnetic bandgap (EBG) structure is introduced. At the heart of this method is the idea to understand and properly utilize the complex interactions between the dipole impedance and the EBG reflection phase characteristics. Using the proposed technique a thin wideband printed dipole is designed, fabricated and tested. The antenna can satisfy applications, such as Digital Communication System (DCS, 1.71-1.88 GHz), Global System for Mobile Communication (GSM, 1.85-1.99 GHz), Personal Communication System (PCS, 1.85-2.05 GHz), Universal Mobile Telecommunication System (UMTS, 1.92-2.17 GHz) and Wireless Local area Network (WLAN, 2.4-2.485 GHz) …

Spectrally Shaped Generalized Mc-Ds-Cdma With Dual Band Combining For Increased Diversity, Wenhui Xiong, David W. Matolak

Faculty Publications

A new multicarrier spread spectrum modulation scheme is proposed in this paper. This scheme uses sinusoidal chip waveforms to shape the spectrum of each subcarrier of a multicarrier direct sequence spread spectrum (DS-SS) signal. As a result, each subcarrier has two distinct spectral lobes, one a lower sideband (LSB) and the other an upper sideband (USB). By properly selecting the parameters of the sinusoidal chip waveforms, the two sideband signals can be made to undergo independent fading in a dispersive fading channel. These two independently-faded sideband signals, when combined at the receiver, provide diversity gain to the system. Our analysis …

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

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 …

Gene Rearrangement Analysis And Ancestral Order Inference From Chloroplast Genomes With Inverted Repeat, Feng Yue, Liying Cui, Claude W. Depamphilis, Bernard M.E. Moret, Jijun Tang

Faculty Publications

Background
Genome evolution is shaped not only by nucleotide substitutions, but also by structural changes including gene and genome duplications, insertions, deletions and gene order rearrangements. The most popular methods for reconstructing phylogeny from genome rearrangements include GRAPPA and MGR. However these methods are limited to cases where equal gene content or few deletions can be assumed. Since conserved duplicated regions are present in many chloroplast genomes, the inference of inverted repeats is needed in chloroplast phylogeny analysis and ancestral genome reconstruction.

Results
We extend GRAPPA and develop a new method GRAPPA-IR to handle chloroplast genomes. A test of GRAPPA-IR …

Comparing Discrimination And Cfa For Selecting Tracking Features, Damian M. Lyons, D. Frank Hsu

Faculty Publications

The ability of a tracker to isolate the foreground target from the background of an image is crucially dependent on the set of features selected for tracking. Collins & Liu [2] propose an on-line, adaptive approach to selecting the set of features based on the insight that the set of features that best discriminate between target and background classes is the best set to use for tracking. In previous work [10], we have proposed an approach based on Combinatorial Fusion Analysis for selecting features for Real-Time tracking. We discuss the relative merits of the two methods and motivate their combination …

Efficient Peer Assignment For Low-Latency Transmission Of Scalable Coded Images, Xiao Su, Tao Wang

Faculty Publications

In this paper, we propose efficient peer assignment algorithms for low-latency transmission of scalable coded images in peer-to-peer networks, in which peers may dynamically join and leave the networks. The objective of our algorithm is to minimize the transmission time of a requested image that is scalable coded. When an image is scalable coded in different bit rates, the bit stream encoded in a lower bit rate is a prefix subset of the one encoded in a higher bit rate. Therefore, a peer with the same requested image coded in any bit rate, even when it is different from the …

Globally Optimal Grouping For Symmetric Closed Boundaries By Combining Boundary And Region Information, Joachim S. Stahl, Song Wang

Faculty Publications

Many natural and man-made structures have a boundary that shows a certain level of bilateral symmetry, a property that plays an important role in both human and computer vision. In this paper, we present a new grouping method for detecting closed boundaries with symmetry. We first construct a new type of grouping token in the form of symmetric trapezoids by pairing line segments detected from the image. A closed boundary can then be achieved by connecting some trapezoids with a sequence of gap-filling quadrilaterals. For such a closed boundary, we define a unified grouping cost function in a ratio form: …

Wideband Smaller Unit-Cell Planar Ebg Structures And Their Application, M. Faisal Abedin, Mohammed Z. Azad, Mohammod Ali

Faculty Publications

A new low-cost smaller unit-cell planar electromagnetic bandgap (ERG) structure operating at the lower GHz frequencies (below 6 GHz) is proposed. ERG structures based on this new geometry are designed on a number of commonly available substrates. Characteristics of such structures, such as bandgap and reflection phase profile are analyzed. a simple empirical model is proposed to predict the surface wave stopband frequency of the proposed ERG structure. Finally, a low-profile dipole antenna is designed and tested for operation on the ERG structure.

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 …

Multi-Class Classification Fusion Using Boosting For Identifying Steganography Methods, Benjamin M. Rodriguez, Gilbert L. Peterson

Faculty Publications

No abstract provided.

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 …

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

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

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

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 …