Engineering Commons^™

Nano-Raman Spectroscopy And Surface Nanostructuring Using Near-Field Optics, Kaijun Yi

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

To satisfy the development of nanoscience and nanotechnology, techniques to characterize and fabricate nanostructures and nanodevices are in great demand. Laser, as a unique monochromatic and coherent light source, meets the needs because it exhibits the potential to reveal some vital information of the materials. However, the applications of laser technology to nanoscience and nanotechnology are facing a severe challenge: the spatial resolution cannot be further enhanced to achieve nanometer scales due to the optical diffraction limit associated with conventional optics. In response to this challenge, near-field optics has been emerging as a new scientific area to deal with optical …

Ultraviolet And Pulsed Electric Field Treatments Have Additive Effect On Inactivation Of E. Coli In Apple Juice, T. K. Gachovska, Saurabh Kumar, Harshanardhan Thippareddi, F. Williams

P. F. (Paul Frazer) Williams Publications

Apple juice inoculated with Escherichia coli ATCC 23472 was processed continuously using either ultraviolet (UV), high-voltage pulsed electric field (PEF), or a combination of the PEF and UV treatment systems. Apple juice was pumped through either of the systems at 3 flow rates (8, 14, and 20 mL/min). E. coli was reduced by 3.46 log CFU/mL when exposed in a 50 cm length of UV treatment chamber at 8 mL/min (2.94 s treatment time with a product temperature increase of 13 °C). E. coli inactivation of 4.87 log CFU/mL was achieved with a peak electric field strength of 60 kV/cm …

Description Of Versatile Optical Polarimetric Scatterometer That Measures All 16 Elements Of The Mueller Matrix For Reflection And Transmission: Application To Measurements Of Scatter Cross Sections, Ellipsometric Parameters, Optical Activity, And The Complex Chiral Parameters, Ezekiel Bahar, Robert D. Kubik

Department of Electrical and Computer Engineering: Faculty Publications

A detailed description of an optical polarimetric scatterometer, its capabilities, and special application are presented. This instrument measures the 44 Mueller matrix elements as well as bidirectional reflective distribution functions scatter cross sectionsfor light that is scattered from a target. Incident polarized light at wavelengths =0.6328 and =1.06 m can be directed toward the target in an arbitrary direction. The receiver can be located anywhere in the solid angle 4. Backscatter measurements, most commonly used in remote sensing, can also be obtained. The scatterometer has been used to validate different analytical/numerical solutions to a broad class of electromagnetic scattering problems, …

Sample Analysis Methodology Utilizing Electromagnetic Radiation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker

Department of Electrical and Computer Engineering: Faculty Publications

Simultaneous use of wavelengths in at least two ranges selected from RADIO, MICRO, FIR, IR, NIR-VIS-NUV, UV, DUV, VUV, EUV, XRAY in a regression procedure to evaluate parameters in mathematical dispersion structures to model dielectric functions.

Sample Analysis Methodology Utilizngelectromagnetic Radation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker

Department of Electrical and Computer Engineering: Faculty Publications

Simultaneous use of wavelengths in at least two ranges Selected from RADIO, MICRO. FIR, IR, NIR-VIS-NUV. UV, DUV, VUV EUV, XRAY in a regression procedure to evaluate parameters in mathematical dispersion structures to model dielectric functions.

System For Reducing Stress Induced Effects Duringdetermination Of Fluid Optical Constants, Thomas E. Tiwald, John A. Woollam, Galen L. Pfeiffer, Blaine D. Johs, Craig M. Herzinger

Department of Electrical and Computer Engineering: Faculty Publications

A system for determination of optical constants of liquids, including provision for reducing stress induced effects while obtaining data.

Fabrication Of Nanostructures With High Electrical Conductivity On Silicon Surfaces Using A Laser-Assisted Scanning Tunneling Microscope, Kaijun Yi, Z. Y. Yang, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Nanostructures with high electrical conductivity were fabricated on silicon surfaces using a laser-assisted scanning tunneling microscope (LA-STM). The nanostructures, dots and lines, were fabricated on H-passivated p-doped silicon (110) surfaces. By precisely controlling the experimental conditions such as pulse energy and tip-surface gap distance, feature sizes (dot diameters and line widths) and heights of the fabricated nanostructures could be controlled. For instance, a dot with a diameter of 30 nm and a line with a width of 30 nm were obtained. In addition, scanning tunneling microscopy investigation of the structures revealed that their band gaps were changed during the …

The Average Mutual Information Profile As A Genomic Signature, Mark Bauer, Sheldon Schuster, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: Occult organizational structures in DNA sequences may hold the key to understanding functional and evolutionary aspects of the DNA molecule. Such structures can also provide the means for identifying and discriminating organisms using genomic data. Species specific genomic signatures are useful in a variety of contexts such as evolutionary analysis, assembly and classification of genomic sequences from large uncultivated microbial communities and a rapid identification system in health hazard situations.
Results: We have analyzed genomic sequences of eukaryotic and prokaryotic chromosomes as well as various subtypes of viruses using an information theoretic framework. We confirm the existence of a …

A Scalable Clustered Camera System For Multiple Object Tracking, Senem Velipasalar, Jason Schlessman, Cheng-Yao Chen, Wayne H. Wolf, Jaswinder P. Singh

Department of Electrical and Computer Engineering: Faculty Publications

Reliable and efficient tracking of objects by multiple cameras is an important and challenging problem, which finds wide-ranging application areas. Most existing systems assume that data from multiple cameras is processed on a single processing unit or by a centralized server. However, these approaches are neither scalable nor fault tolerant. We propose multicamera algorithms that operate on peer-to-peer computing systems. Peer-to-peer vision systems require codesign of image processing and distributed computing algorithms as well as sophisticated communication protocols, which should be carefully designed and verified to avoid deadlocks and other problems. This paper introduces the scalable clustered camera system, which …

Full-Wave Finite-Difference Time-Domain Simulation Of Electromagnetic Cloaking Structures, Yan Zhao, Christos Argyropoulos, Yang Hao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a radial dependent dispersive finitedifference time-domain method for the modeling of electromagnetic cloaking structures. The permittivity and permeability of the cloak are mapped to the Drude dispersion model and taken into account in dispersive FDTD simulations. Numerical simulations demonstrate that under ideal conditions, objects placed inside the cloak are ‘invisible’ to external electromagnetic fields. However for the simplified cloak based on linear transformations, the back scattering has a similar level to the case of a PEC cylinder without any cloak, rendering the object still being ‘visible’. It is also demonstrated numerically that the simplified cloak based on …

Genomic Counter-Stress Changes Induced By The Relaxation Response, Jeffery A. Dusek, Hasan H. Otu, Ann L. Wohlhueter, Manoj Bhasin, Luiz F. Zerbini, Marie G. Joseph, Herbert Benson, Towia A. Libermann

Department of Electrical and Computer Engineering: Faculty Publications

Background: Mind-body practices that elicit the relaxation response (RR) have been used worldwide for millennia to prevent and treat disease. The RR is characterized by decreased oxygen consumption, increased exhaled nitric oxide, and reduced psychological distress. It is believed to be the counterpart of the stress response that exhibits a distinct pattern of physiology and transcriptional profile. We hypothesized that RR elicitation results in characteristic gene expression changes that can be used to measure physiological responses elicited by the RR in an unbiased fashion.

Methods/Principal Findings: We assessed whole blood transcriptional profiles in 19 healthy, long-term practitioners of daily RR …

Proteomic Identification Of Interleukin-2 Therapy Response In Metastatic Renal Cell Cancer, Jon Jones, Hasan H. Otu, Franck Grall, Dimitrios Spentzos, Handan Can, Manuel Aivado, Arie S. Belldegrun, Allan J. Pantuck, Towia A. Libermann

Department of Electrical and Computer Engineering: Faculty Publications

Introduction—To detect a predictive protein profile that distinguishes between IL-2 therapy responders and non-responders among metastatic RCC patients we used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF-MS).

Materials and Methods—Protein extracts of 56 metastatic clear cell RCC patients obtained from radical nephrectomy specimens and prior to IL-2 therapy were applied to protein chip arrays of different chromatographic properties and analyzed using SELDI TOF-MS. A class prediction algorithm was applied to identify a subset of protein peaks whose expression values were associated with IL-2 response status. Multivariate analysis was performed to assess the association between the proteomic profile …

Gene Expression Analysis Of Embryonic Stem Cells Expressing Ve-Cadherin (Cd144) During Endothelial Differentiation, Vesna Nikolova-Krstevski, Manoj Bhasin, Hasan H. Otu, Towia A. Libermann, Peter Oettgen

Department of Electrical and Computer Engineering: Faculty Publications

Background: Endothelial differentiation occurs during normal vascular development in the developing embryo. This process is recapitulated in the adult when endothelial progenitor cells are generated in the bone marrow and can contribute to vascular repair or angiogenesis at sites of vascular injury or ischemia. The molecular mechanisms of endothelial differentiation remain incompletely understood. Novel approaches are needed to identify the factors that regulate endothelial differentiation.

Methods: Mouse embryonic stem (ES) cells were used to further define the molecular mechanisms of endothelial differentiation. By flow cytometry a population of VEGF-R2 positive cells was identified as early as 2.5 days after differentiation …

Differential Expression Of Gadd45Β In Normal And Osteoarthritic Cartilage: Potential Role In Homeostasis Of Articular Chondrocytes, Kosei Ijiri, Luiz F. Zerbini, Haibing Peng, Hasan H. Otu, Kaneyuki Tsuchimochi, Miguel Otero, Cecilia Dragomir, Nicole Walsh, Benjamin E. Bierbaum, David Mattingly, Geoff Van Flandern, Setsuro Komiya, Thomas Aigner, Towia A. Libermann, Mary B. Goldring

Department of Electrical and Computer Engineering: Faculty Publications

Objective—Our previous study suggested that growth arrest and DNA damage–inducible protein 45β (GADD45β) prolonged the survival of hypertrophic chondrocytes in the developing mouse embryo. This study was undertaken, therefore, to investigate whether GADD45β plays a role in adult articular cartilage.

Methods—Gene expression profiles of cartilage from patients with late-stage osteoarthritis (OA) were compared with those from patients with early OA and normal controls in 2 separate microarray analyses. Histologic features of cartilage were graded using the Mankin scale, and GADD45β was localized by immunohistochemistry. Human chondrocytes were transduced with small interfering RNA (siRNA)–GADD45 …

A Theoretical Framework For Quality-Aware Cross-Layer Optimized Wireless Multimedia Communications, Song Ci, Haohong Wang, Dalei Wu

Department of Electrical and Computer Engineering: Faculty Publications

Although cross-layer has been thought as one of themost effective and efficient ways formultimedia communications over wireless networks and a plethora of research has been done in this area, there is still lacking of a rigorous mathematical model to gain indepth understanding of cross-layer design tradeoffs, spanning from application layer to physical layer. As a result, many existing cross-layer designs enhance the performance of certain layers at the price of either introducing side effects to the overall system performance or violating the syntax and semantics of the layered network architecture. Therefore, lacking of a rigorous theoretical study makes existing cross-layer …

Effects Of Wind Field Inhomogeneities On Doppler Beam Swinging Revealed By An Imaging Radar, B.L. Cheong, T.-Y. Yu, Robert D. Palmer, K.-F. Yang, Michael Hoffman, S.J. Frasier, F.J. Lopez-Dekker

Department of Electrical and Computer Engineering: Faculty Publications

In this work, the accuracy of the Doppler beam-swinging (DBS) technique for wind measurements is studied using an imaging radar—the turbulent eddy profiler (TEP) developed by the University of Mas- sachusetts, with data collected in summer 2003. With up to 64 independent receivers, and using coherent radar imaging (CRI), several hundred partially independent beams can be formed simultaneously within the volume defined by the transmit beam. By selecting a subset of these beams, an unprecedented number of DBS configurations with varying zenith angle, azimuth angle, and number of beams can be investigated. The angular distributions of echo power and radial …

Aspects Of Producing, Directing, Conditioning, Impinging And Detecting Spectroscopic Electromagnetic Radiation From Small Spots On Samples, Martin M. Liphardt, Ping He, Blaine D. Johs, Galen L. Pfeiffers, James D. Welch, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Sytems and mehtods for providing and enhancing electromagnetic radiation beam radail energy homogeneity and intensity vs. wavelength content, for reliably directing electromagnetic radiation emitted by a source thereof in a common direction, for achromatically reducing spot size on a sample (eg. liquid cavity containing lenses and low aberration 1:1 imaging systems modified to perform as spatial filters), and for directing directing different wavelengths into different detectors, in ellipsometer, polarizer or the like systems.

System And Method Ofselectively Monitoring Sample Front And Backside Reflections In Ellipsometer And The Like Systems, James D. Welch, John A. Woollam, Martin M Liphardt

Department of Electrical and Computer Engineering: Faculty Publications

A spectrophotometer, reflectometer, ellipsometer polarimeter or the like system having a detector means for independently intercepting electromagnetic radiation reflected from a sample frontside or backside, and methodology for pursuing less correlated determination of refractive index and thickness values.

Grammar-Based Distance In Progressive Multiple Sequence Alignment, David Russell, Hasan H. Otu, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: We propose a multiple sequence alignment (MSA) algorithm and compare the alignment-quality and execution-time of the proposed algorithm with that of existing algorithms. The proposed progressive alignment algorithm uses a grammar-based distance metric to determine the order in which biological sequences are to be pairwise aligned. The progressive alignment occurs via pairwise aligning new sequences with an ensemble of the sequences previously aligned.
Results: The performance of the proposed algorithm is validated via comparison to popular progressive multiple alignment approaches, ClustalW and T-Coffee, and to the more recently developed algorithms MAFFT, MUSCLE, Kalign, and PSAlign using the BAliBASE 3.0 …

Ex-Situ And In-Situ Selenization Of Copper-Indium And Copper-Boron Thin Films, Rodney J. Soukup, Natale J. Ianno, Chad Kamler, Martin Diaz, Shuchi Sharma, James Huguenin-Love, Jiri Olejnicek

Department of Electrical and Computer Engineering: Faculty Publications

It has recently been established that the ideal bandgap for terrestrial photovoltaics is 1.37 eV and the bandgap for CulnSe2 is only around 1.04 eV. Thus, a larger bandgap is needed. However, neither the substitution of Ga nor of AI has made a high efficiency solar cell absorber with a band gap of 1.37 eV possible. B, an even smaller atom, should require less atomic substitution than either Ga or AI to achieve a wider bandgap. In order to fabricate a thin film of Culn_xB_1-xSe₂ (CIBS), Cu, In and B were deposited from a variety …

Analysis Of Energy Efficiency In Fading Channels Under Qos Constraints, Deli Qiao, Mustafa Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

Energy efficiency in fading channels in the presence of QoS constraints is studied. Effective capacity, which provides the maximum constant arrival rate that a given process can support while satisfying statistical delay constraints, is considered. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation, rather than the Shannon capacity, and energy requirements under QoS constraints are identified. The analysis is conducted for the case in which perfect channel side information (CSI) is available at the receiver and also for the case in which perfect CSI is available at both the receiver …

Reaction Pathway Insights Into The Solvothermal Preparation Of Culn1- XGaXSe2 Nanocrystalline Materials, Christopher L. Exstrom, Scott A. Darveau, Andrea L. Martinez-Skinner, Matt Ingersoll, Jiri Olejnicek, Anatole Mirasano, Adam T. Haussler, James Huguenin-Love, Chad Kamler, Martin Diaz, Natale J. Ianno, Rodney J. Soukup

Department of Electrical and Computer Engineering: Faculty Publications

Reaction pathway investigations of the solvothermal preparation of nanocrystalline Culn_{1- x}Ga_xSe₂ in triethylenetetramine reveal the early formation of a previously unreported Cu_2-xSe(S) intermediate. Over 24 hours, this reacts with In and Se species to form CulnSe₂(s). If Ga is present, the reaction proceeds over an additional 48 hours to form Culn_1-xGa_xSe₂. Adding ammonium halide salts reduces the CulnSe₂ formation time to as little as 30 minutes. It is proposed that in these cases, Cu_2-xSe particle growth is limited via a competitive Cu-halide …

Grid Connection Requirements And Solutions For Dfig Wind Turbines, Wei Qiao, Ronald G. Harley

Department of Electrical and Computer Engineering: Faculty Publications

As the number and size of windfarms continue to grow,many countries have established or are developing a set of specific requirements (i.e., grid codes) for operation and grid connection of windfarms. The objective of these grid codes is to ensure that wind farms do not adversely affect the power system operation with respect to security of supply, reliability and power quality. This paper reviews major grid code requirements for wind farms, and investigates various technologies developed by and solutions proposed by researchers and wind turbine manufactures in order to meet these requirements. In addition, some ofthe authors' work on these …

Reliability-Based Stand-Alone Photovoltaic System Sizing Design- A Case Study, Haifeng Ge, Liqin Ni, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

This paper introduces a method for designing a standalone photovoltaic system to improve the load point reliability, extend the operation life, and minimize the design cost. This approach examines the impacts of solar panel sizes, tilt angles and battery volumes toward load point reliability, as well as the expected system life, by using real insolation data in a given location and random load burdens. The reliability evaluation incorporating solar insolation variations and load point uncertainty is performed. Life evaluation of battery is included in this paper with consideration of the battery State of Charge (SoC) history. The Economical analysis to …

A Quantitative Study Of Mobility Impact For Real- Time Services On A Wi-Fi Multi-Hop Network, Ting Zhou, Hamid Sharif, Michael Hempel, Puttipong Mahasukhon, Wei Wang, Song Ci

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we analyze the performance of mobile real time services in a large-scale IEEE 802.11 multi-hop network. We present our field measurements with discussion of performance bottlenecks for VoIP services under mobile scenarios. We utilized our test bed which is located in Nebraska and supported by the University of Nebraska-Lincoln (UNL), US Federal Railroads Administrations (FRA), and major US railroad companies. Our UNL-FRA test bed consists of 8 outdoor access point towers, which are deployed along 3.5 mile of BNSF railroad. Passive measurement approaches are taken to ensure the integrity of collected data and multi-layer stream based packet …

Average Min-Sum Decoding Of Ldpc Codes, Nathan Axvig, Deanna Dreher, Katherine Morrison, Eric T. Psota, Lance C. Pérez, Judy L. Walker

Department of Mathematics: Faculty Publications

Simulations have shown that the outputs of minsum (MS) decoding generally behave in one of two ways: the output either eventually stabilizes at a codeword or eventually cycles through a finite set of vectors that may include both codewords and non-codewords. This inconsistency in MS across iterations has significantly contributed to the difficulty in studying the performance of this decoder. To overcome this problem, a new decoder, average min-sum (AMS), is proposed; this decoder outputs the average of the min-sum output vectors over a finite set of iterations. Simulations comparing MS, AMS, linear programming (LP) decoding, and maximum likelihood (ML) …