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Full-Text Articles in Engineering
Optical Constants And Roughness Study Of Dc Magnetron Sputtered Iridium Films, Li Yan, John A. Woollam
Optical Constants And Roughness Study Of Dc Magnetron Sputtered Iridium Films, Li Yan, John A. Woollam
Department of Electrical and Computer Engineering: Faculty Publications
Extremely smooth thin films of iridium have been deposited onto superpolished fused silica substrates using dc magnetron sputtering in an argon plasma. The influence of deposition process parameters on film microroughness has been investigated. In addition, film optical constants have been determined using variable angle spectroscopic ellipsometry, over the spectral range from vacuum ultraviolet to middle infrared (140 nm–35 μm). Because the Ir films were optically thick and the surface roughnesses were measured by atomic force microscopy then accounted for in the optical model, the as-determined film optical constants are expected to be the best available for Ir bulk metals, …
Self-Assembled Networks With Neural Computing Attributes, Supriyo Bandyopadhyay, L. Menon, N. Kouklin, P. F. Williams, Natale J. Ianno
Self-Assembled Networks With Neural Computing Attributes, Supriyo Bandyopadhyay, L. Menon, N. Kouklin, P. F. Williams, Natale J. Ianno
P. F. (Paul Frazer) Williams Publications
Two-dimensional arrays of vertical quantum wire Esaki tunnel diodes, laterally connected to their nearest neighbors by resistive/capacitive connections, constitute a powerful and versatile neuromorphic architecture that can function as classical Boolean logic circuits, associative memory, image processors, and combinatorial optimizers. In this paper, we discuss the basic philosophy behind adopting this architecture for nanoelectronic circuits and report on our experimental progress towards synthesizing this system.
Oxygen Plasma Effects On Optical Properties Of Znse Films, Li Yan, John A. Woollam, Eva Franke
Oxygen Plasma Effects On Optical Properties Of Znse Films, Li Yan, John A. Woollam, Eva Franke
Department of Electrical and Computer Engineering: Faculty Publications
Zinc selenide is an infrared transparent semiconductor material being considered for use in space as an infrared optical coating. In this work, zinc selenide thin films of different thicknesses were exposed to an electron cyclotron resonance generated oxygen plasma, often used to ‘‘simulate’’ the low earth orbital environment. The maximum fluence used in our experiments was equivalent to ~16 years in the low earth orbital environment. ZnSe thin film optical constants (both before and after oxygen plasma exposure) were determined using variable angle spectroscopic ellipsometry from the vacuum ultraviolet at 146 nm through the middle infrared to 40 μm. A …
Information Efficiency In Hyperspectral Imaging Systems, Stephen E. Reichenbach, Luyin Cao, Ram M. Narayanan
Information Efficiency In Hyperspectral Imaging Systems, Stephen E. Reichenbach, Luyin Cao, Ram M. Narayanan
Department of Electrical and Computer Engineering: Faculty Publications
In this work we develop a method for assessing the information density and efficiency of hyperspectral imaging systems that have spectral bands of non-uniform width. Imaging system designs with spectral bands of nonuniform width can efficiently gather information about a scene by allocating bandwidth among the bands according to their information content. The information efficiency is the ratio of information density to data density and is a function of the scene’s spectral radiance, hyperspectral system design, and signal-to-noise ratio. The assessment can be used to produce an efficient system design. For example, one approach to determining the number and width …
Nanostructures With Small- And Large-Scale Periodic And Random Rough Surfaces And Lateral Fluctuations In The Permittivity And Permeability-Scattered Near Fields, Ezekiel Bahar
Department of Electrical and Computer Engineering: Faculty Publications
The scattered electromagnetic near fields due to fluctuations in the surface height and/or lateral variations in the electromagnetic medium parameters are evaluated using a full-wave approach. Since the scales of the height and medium fluctuations considered could be significantly smaller or larger than the electromagnetic wavelengths, the familiar perturbation and physical/geometrical optics solutions cannot be used nor is it possible to investigate subwave length features based on far-field measurements. The full-wave approach employs complete field expansion that includes propagating and evanescent waves as well as lateral waves and surface waves, which are not accounted for in the perturbation and physical …
Experimental Study Of Streamers In Pure N2 And N2/O2 Mixtures And A ≈13 Cm Gap, Won J. Yi, P. F. Williams
Experimental Study Of Streamers In Pure N2 And N2/O2 Mixtures And A ≈13 Cm Gap, Won J. Yi, P. F. Williams
P. F. (Paul Frazer) Williams Publications
Empirical data on streamer formation and propagation in near-atmospheric pressure N2 and N2/O2mixtures are presented. The data were obtained primarily from high-speed, high-sensitivity shutter and streak photography of streamers produced in a ≈13 cm gap. The streamer propagation velocity as a function of applied voltage, polarity, total pressure, and O2 concentration are provided. In addition, information on streamer bifurcation, and streamer shape and size is included.
The breakdown process has two phases: a fast phase featuring the propagation of streamers, and much slower phase involving the heating of the gas to form the spark …
Cxquery: A Novel Xml Query Language, Peter Revesz, Yi Chen
Cxquery: A Novel Xml Query Language, Peter Revesz, Yi Chen
CSE Conference and Workshop Papers
XML is becoming the data exchange standard on the Internet. Previously proposed XML query languages, such as XQuery, Quilt, YALT, Lorel, and XML-QL, lack schema definition of the query result; therefore, they are limited for defining views, integrating data, updating, and further querying, all of which are often needed in e-Business applications. We propose a novel XML query language called CXQuery, which defines the schema of the query results explicitly and can easily define views, and integrate, update, and query XML data. In addition, CXQuery can express spatial and spatio-temporal queries using a constraint-based querying approach.
Femtosecond Laser Utilization Methods And Apparatus And Method For Producing Nanoparticles, Dennis R. Alexander
Femtosecond Laser Utilization Methods And Apparatus And Method For Producing Nanoparticles, Dennis R. Alexander
Department of Electrical and Computer Engineering: Faculty Publications
The present invention teaches various femtosecond machining and drilling apparatus and processes for fabricating tools and the like from both traditional and non-traditional materials. Also described are novel tools such as scalpels, and nozzles fabricated from the apparatus and processes of the present invention. Likewise, the present invention may be utilized in both a novel propulsion system and the production of materials formed from nanometer sized particles and the like.
Implementation And Validation Of Range Imaging On A Uhf Radar Wind Profiler, P. B. Chilson, Tian-You Yu, Richard G. Strauch, Andreas Muschinski, Robert D. Palmer
Implementation And Validation Of Range Imaging On A Uhf Radar Wind Profiler, P. B. Chilson, Tian-You Yu, Richard G. Strauch, Andreas Muschinski, Robert D. Palmer
Department of Electrical and Computer Engineering: Faculty Publications
The available range resolution of pulsed radar wind profilers is usually limited by bandwidth restrictions. Range imaging (RIM) has recently been developed as a means of mitigating these limitations by operating the wind profilers over a small set of distinct transmitter frequencies. A constrained optimization method can then be used to generate high-resolution maps of the reflectivity field as a function of range. This paper presents a description of how the RIM technique has been recently implemented on the Platteville 915-MHz tropospheric profiler, the first such implementation at UHF. Examples of data collected during a two-part experiment on 10 April …
An Airborne Low-Cost Sar For Remote Sensing: Hardware Design And Development, Ram Narayanan, Paul C. Cantu, Xiaojian Xu
An Airborne Low-Cost Sar For Remote Sensing: Hardware Design And Development, Ram Narayanan, Paul C. Cantu, Xiaojian Xu
Department of Electrical and Computer Engineering: Faculty Publications
An airborne low-cost synthetic aperture radar (SAR) is under development at the University of Nebraska-Lincoln. The SAR system is an X-band, stepped-chirp frequency modulation (SCFM) radar system. One of its unique features is that the waveform generation consists of a timing-controlled D/A converter and VCO arrangement to synthesize the SCFM signal, whereby allowing for less design complexity and a much lower overall system cost. In this paper, we present a brief description of the system and some computer simulation results.
Shape-Based Change Detection And Information Mining In Remote Sensing, Jiang Li, Ram M. Narayanan
Shape-Based Change Detection And Information Mining In Remote Sensing, Jiang Li, Ram M. Narayanan
Department of Electrical and Computer Engineering: Faculty Publications
Change detection is an important application of remote sensing. This paper presents our approach to retrieve and represent interesting shapes in the remotely sensed imagery using supervised classification, edge detection, and polygonal approximation techniques, and to compare the shape similarity by a computationally efficient metric. The experiments were conducted on a time series of calibrated and registered Landsat MSS images, covering the scene of the lakes at the western Nebraska. The results show the effectiveness of the shape-based change detection approach, which is potentially useful for specific applications such as the study of the lake change response to short or …
A Multiwavelength Airborne Polarimetric Lidar For Vegetation Remote Sensing: Instrumentation And Preliminary Test Results, Songxin Ran, Ram M. Narayanan
A Multiwavelength Airborne Polarimetric Lidar For Vegetation Remote Sensing: Instrumentation And Preliminary Test Results, Songxin Ran, Ram M. Narayanan
Department of Electrical and Computer Engineering: Faculty Publications
Several spaceborne and airborne lidar systems have been launched for vegetation canopy studies. Previous research has shown that lidars are useful tools for remote sensing of vegetation architecture. To support its Airborne Remote Sensing Program, the University of Nebraska has developed a multiwavelength airborne polarimetric lidar system. This system employs a Nd:YAG laser which emits radiation at two wavelengths: the fundamental at 1064 nm and the frequency-doubled at 532 nm. Both laser beams are highly linearly polarized (100: 1 extinction ratio) and have a beam divergence angle of ~4 mrad. The receiver consists of four channels, which enable dual-wavelength and …