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Full-Text Articles in Engineering

Photonic Band Tuning In 2d Photonic Crystals By Atomic Layer Deposition, Elton Graugnard, Davy P. Gaillot, Simon N. Dunham, Curtis W. Neff, Tsuyoshi Yamashita, Christopher J. Summers Oct 2006

Photonic Band Tuning In 2d Photonic Crystals By Atomic Layer Deposition, Elton Graugnard, Davy P. Gaillot, Simon N. Dunham, Curtis W. Neff, Tsuyoshi Yamashita, Christopher J. Summers

Materials Science and Engineering Faculty Publications and Presentations

Atomic layer deposition (ALD) has become a powerful tool for the fabrication of high quality 3-dimentional photonic crystals (PCs) from both inorganic (opal) and organic (holographically patterned polymer) templates [1,2]. With ALD, highly conformal films can be grown with a precision of 0.05 nm, which, when combined with the availability of a wide range of low temperature film growth protocols, enables a high degree of control over material and structural properties to precisely tune optical properties [3]. Two-dimensional photonic crystals have been developed extensively for applications in optical interconnects, beam steering, and sensor devices; and are predominantly fabricated by electron-beam …


Covariance Searches For Ncrna Gene Finding, Jennifer A. Smith Sep 2006

Covariance Searches For Ncrna Gene Finding, Jennifer A. Smith

Electrical and Computer Engineering Faculty Publications and Presentations

The use of covariance models for non-coding RNA gene finding is extremely powerful and also extremely computationally demanding. A major reason for the high computational burden of this algorithm is that the search proceeds through every possible start position in the database and every possible sequence length between zero and a user-defined maximum length at every one of these start positions. Furthermore, for every start position and sequence length, all possible combinations of insertions and deletions leading to the given sequence length are searched. It has been previously shown that a large portion of this search space is nowhere near …


A Study Of Finite State Machine Coding Styles For Implementation In Fpgas, Nader I. Rafla, Brett L. Davis Aug 2006

A Study Of Finite State Machine Coding Styles For Implementation In Fpgas, Nader I. Rafla, Brett L. Davis

Electrical and Computer Engineering Faculty Publications and Presentations

Finite State Machines (FSM), are one of the more complex structures found in almost all digital systems today. Hardware Description Languages are used for high-level digital system design. VHDL (VHSIC Hardware Description Language) provides the capability of different coding styles for FSMs. Therefore, a choice of a coding style is needed to achieve specific performance goals and to minimize resource utilization for implementation in a re-configurable computing environment such as an FPGA. This paper is a study of the tradeoffs that can be made by changing coding styles. A comparative study on three different FSM coding styles is shown to …


A Genetic Algorithms Approach To Non-Coding Rna Gene Searches, Jennifer A. Smith Jul 2006

A Genetic Algorithms Approach To Non-Coding Rna Gene Searches, Jennifer A. Smith

Electrical and Computer Engineering Faculty Publications and Presentations

A genetic algorithm is proposed as an alternative to the traditional linear programming method for scoring covariance models in non-coding RNA (ncRNA) gene searches. The standard method is guaranteed to find the best score, but it is too slow for general use. The observation that most of the search space investigated by the linear programming method does not even remotely resemble any observed sequence in real sequence data can be used to motivate the use of genetic algorithms (GAs) to quickly reject regions of the search space. A search space with many local minima makes gradient decent an unattractive alternative. …


Accelerated Non-Coding Rna Searches With Covariance Model Approximations, Jennifer A. Smith Jul 2006

Accelerated Non-Coding Rna Searches With Covariance Model Approximations, Jennifer A. Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Covariance models (CMs) are a very sensitive tool for finding non-coding RNA (ncRNA) genes in DNA sequence data. However, CMs are extremely slow. One reason why CMs are so slow is that they allow all possible combinations of insertions and deletions relative to the consensus model even though the vast majority of these are never seen in practice. In this paper we examine reduction in the number of states in covariance models. A simplified CM with reduced states which can be scored much faster is introduced. A comparison of the results of a full CM versus a reduced-state model found …


Dial 2004 Working Group Report On Acquisition Quality Control, Elisa H. Barney Smith, Henry Baird, William Barrett, Frank Le Bourgeois, Xiaofan Lin, George Nagy, Steve Simske Apr 2006

Dial 2004 Working Group Report On Acquisition Quality Control, Elisa H. Barney Smith, Henry Baird, William Barrett, Frank Le Bourgeois, Xiaofan Lin, George Nagy, Steve Simske

Electrical and Computer Engineering Faculty Publications and Presentations

This report summarizes the discussions of the Working Group on Acquisition Quality at the International Workshop on Document Image Analysis for Libraries, Palo Alto, CA, 23-24 January 2004. Acquisition of the image is one of the most time intensive components of forming a digital library, and the quality of the acquisition will affect all later stages of the digital library project. The current state of the art in acquisition is analyzed. Problems and suggested improvements for image acquisition and storage formats and the special problems associated with acquisition from microfilm follows. A list of general suggestions was developed which was …


Between Microscopic And Mesoscopic Descriptions Of Twin-Twin Interaction, Peter Müllner Mar 2006

Between Microscopic And Mesoscopic Descriptions Of Twin-Twin Interaction, Peter Müllner

Materials Science and Engineering Faculty Publications and Presentations

On a microscopic scale, deformation twinning is carried by the motion of twinning disconnections. A disconnection is an interfacial line defect characterized by a Burgers vector, a line vector, and a step vector. The Burgers vector (dislocation component of the disconnection) carries the deformation while the step vector (ledge component) carries the transformation from one twin variant to the other. On a mesoscopic scale, the deformation produced by twinning is a simple shear. A moving disclination dipole provides a mesoscopic model accounting for the twinning shear. Twin – twin interaction processes including the intersection of twins, the formation of structured …


Correlations Beyond The Nearest-Neighbor Level In Grain Boundary Networks, C. A. Schuh, M. Frary Mar 2006

Correlations Beyond The Nearest-Neighbor Level In Grain Boundary Networks, C. A. Schuh, M. Frary

Materials Science and Engineering Faculty Publications and Presentations

Correlations among 'special' and 'general' grain boundaries are studied on two-dimensional networks, by examining the configurational entropy of boundary structures as well as percolation thresholds. Consideration of crystallographic constraints at various length scales reveals that higher-order constraints play a role in boundary connectivity and network structure. Implications for grain boundary engineering are discussed and directions for future work highlighted.


Psf Estimation By Gradient Descent Fit To The Esf, Elisa H. Barney Smith Jan 2006

Psf Estimation By Gradient Descent Fit To The Esf, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Calibration of scanners and cameras usually involves measuring the point spread function (PSF). When edge data is used to measure the PSF, the differentiation step amplifies the noise. A parametric fit of the functional form of the edge spread function (ESF) directly to the measured edge data is proposed to eliminate this. Experiments used to test this method show that the Cauchy functional form fits better than the Gaussian or other forms tried. The effect of using a functional form of the PSF that differs from the true PSF is explored by considering bilevel images formed by thresholding. The amount …


Partitioning Of The Degradation Space For Ocr Training, Elisa H. Barney Smith, Tim Andersen Jan 2006

Partitioning Of The Degradation Space For Ocr Training, Elisa H. Barney Smith, Tim Andersen

Electrical and Computer Engineering Faculty Publications and Presentations

Generally speaking optical character recognition algorithms tend to perform better when presented with homogeneous data. This paper studies a method that is designed to increase the homogeneity of training data, based on an understanding of the types of degradations that occur during the printing and scanning process, and how these degradations affect the homogeneity of the data. While it has been shown that dividing the degradation space by edge spread improves recognition accuracy over dividing the degradation space by threshold or point spread function width alone, the challenge is in deciding how many partitions and at what value of edge …


Thermo-Mechanical Characterization Of Copper Through-Wafer Interconnects, Peter A. Miranda, Amy J. Moll Jan 2006

Thermo-Mechanical Characterization Of Copper Through-Wafer Interconnects, Peter A. Miranda, Amy J. Moll

Electrical and Computer Engineering Faculty Publications and Presentations

Copper through wafer interconnects (TWIs) have become a viable solution to providing interconnectivity between stacked die. In a world where minimizing chip real estate while increasing functionality is the goal for further miniaturization of electronics, TWIs hold a key role as new packaging schemes become critical for overall higher density. Little is known, however, about the impacts of mismatched coefficients of thermal expansion (CTEs) inherent to the materials used in their construction. CTE differences, if left unresolved, can pose reliability issues during TWI operation. This research focuses on providing insight into the stress levels experienced by TWI materials through finite …


Propagation Loss Of Line-Defect Photonic Crystal Slab Waveguides, Wan Kuang, Woo J. Kim, Adam Mock, John O'Brien Jan 2006

Propagation Loss Of Line-Defect Photonic Crystal Slab Waveguides, Wan Kuang, Woo J. Kim, Adam Mock, John O'Brien

Electrical and Computer Engineering Faculty Publications and Presentations

Photonic crystal slab waveguides are created by inserting a linear defect in two-dimensional (2-D) periodic dielectric structures of finite height. Photonic crystals provide 2-D in-plane bandgaps through which light cannot propagate, however, the fact that the waveguide modes must be index-confined in the vertical direction implies that the propagation loss is strongly dependent on the out-of-plane radiation loss. We present a fully three-dimensional finite-difference time-domain numerical model for calculating the out-of-plane radiation loss in photonic crystal slab waveguides. The propagation loss of the single-line defect waveguide in 2-D triangular lattice photonic crystals is calculated for suspended membranes, oxidized lower claddings, …


An Unsupervised Fluoroscopic Analysis Of Knee Joint Kinematics, Charles Scott, Elisa H. Barney Smith Jan 2006

An Unsupervised Fluoroscopic Analysis Of Knee Joint Kinematics, Charles Scott, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Knowledge of the three dimensional positions of bones at a joint as a function of time is required to accurately model joint kinematics. 3-D bone geometry data from a static computer tomography (CT) images can be combined with time sequence information from 2-D video fluoroscopy images to produce 3-D position data over time. The process involves creating virtual X-rays from the CT image through digitally reconstructed radiograph (DRR) projections. Historically, the process of matching the 3-D and 2-D data has required human interaction. We have eliminated the need for manual initialization using a Monte Carlo technique with a variable search …


Low Temperature Co-Fired Ceramics For Micro-Fluidics, John Youngsman, Brian Marx, Martin Schimpf, Scott Wolter, Jeff Glass, Amy Moll Jan 2006

Low Temperature Co-Fired Ceramics For Micro-Fluidics, John Youngsman, Brian Marx, Martin Schimpf, Scott Wolter, Jeff Glass, Amy Moll

Materials Science and Engineering Faculty Publications and Presentations

The miniaturization of analytical instruments and packaging of novel sensors is an area that has attracted significant research interest and offers many opportunities for product commercialization. Low Temperature Co-fired Ceramics (LTCC) is a materials system composed of alumina and glass in an organic binder. LTCC is a good choice for sensor development because of the ease of incorporating features in the ‘green’ or unfired state such as electrical traces, fluidic pathways and passive electrical components. After a firing cycle, what remains is a robust, monolithic device with features embedded in the package. In order for LTCC to be a successful …