Electrical and Computer Engineering Commons^™

Distributed Power Control In Wireless Communication Systems, Sarangapani Jagannathan, A. T. Chronopoulos, S. Ponipireddy

Electrical and Computer Engineering Faculty Research & Creative Works

Energy efficiency is a measure of performance in wireless networks. Therefore, controlling the transmitter power at a given node increases not only battery operating life, but also overall system capacity by successfully admitting new links. It is essential to find effective means of power control in point-to-point, broadcasting and multicasting scenarios. Wireless networking presents formidable challenges, and we consider the problem of unicast or point-to-point (peer-to-peer) communication in wireless networks in the presence of other nodes. We study the feasibility of admitting new links in an wireless network operating area while maintaining quality of service (QoS), in terms of signal-to-interference …

Incorporation Of Cerium And Neodymium In A Uranyl Hydroxide Solid, Chang-Soo Kim, David J. Wronkiewicz, R. J. Finch, E. C. Buck

Electrical and Computer Engineering Faculty Research & Creative Works

The migration behavior of radionuclides in a nuclear-waste repository will be influenced, in part, by their equilibrium solubilities in the presence of radionuclide-bearing solids and/or adsorption affinities as trace components onto the surfaces of solid host phases. Uranium phases that precipitate on the surface of altered spent nuclear fuel may thus influence the mobility of radionuclides released in the near-field environment, since by proximity, these will be the first phases that the radionuclides encounter following their release from the spent fuel matrix. We have evaluated the potential for incorporating radionuclides into crystalline compounds by precipitating uranyl phases from aqueous solutions …

Study Of Relative Effectiveness Of Features In Content-Based Image Retrieval, S. R. Subramanya, Jui Che Teng, Yongjian Fu

Electrical and Computer Engineering Faculty Research & Creative Works

Content-based retrieval in image databases requires appropriate features of images to be derived and used in the indexing and searching process. Fast and accurate retrieval is crucial from a user point of view. The kinds of features used, their organization in suitable data structures, and the similarity search scheme, directly affect the speed and quality of content-based retrieval. In this paper, we evaluate the relative significance of three different image features - geometry, moments, and Fourier descriptors in the context of content-based retrieval, and present experimental results. The evaluation metrics are retrieval quality and search time. These could be used …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Ii Second Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. Up to this point, the second phase has resulted in the design of an experimental setup for the fluid flow experiment. Other experimental activities include the evaluation of a vacuum system are underway. Little reportable progress has …

The Changing Roles Of Analog And Digital Signal Processing In Cmos Image Sensors, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Throughout the years digital signal processing has been encroaching more and more into what had previously been exclusive analog circuit domains. Here we briefly summarize various lines of research in CMOS imaging sensoring technology paying special attention to the gradual transition from analog to digital processing. The transition from continuous-time continuous-value pixels to digital (discrete-time binary-value) pixels could be viewed as the natural final step in the evolution of these imaging circuits in order to achieve wide dynamic range with acceptable signal to noise ratio. After data is read off a digital pixel imager chip, digital signal processing is required …

Increased Mfcc Filter Bandwidth For Noise-Robust Phoneme Recognition, Mark D. Skowronski, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Many speech recognition systems use mel-frequency cepstral coefficient (MFCC) feature extraction as a front end. In the algorithm, a speech spectrum passes through a filter bank of mel-spaced triangular filters, and the filter output energies are log-compressed and transformed to the cepstral domain by the DCT. The spacing of filter bank center frequencies mimics the known warped-frequency characteristics of the human auditory system, yet the bandwidths of these filters are not chosen through biological inspiration. Instead, they are set by aligning endpoints of the triangle, which is itself an arbitrary shape. It is surprising that for such a popular speech …

Wavelength Assignment In All-Optical Networks For Mesh Topologies, Prabhulaiah Bijja

LSU Master's Theses

All-Optical Networks employing Dense Wavelength Division Multiplexing (DWDM) are believed to be the next generation networks that can meet the ever-increasing demand for bandwidth of the end users. This thesis presents some new heuristics for wavelength assignment and converter placement in mesh topologies. Our heuristics try to assign the wavelengths in an efficient manner that results in very low blocking probability. We propose novel static and dynamic assignment schemes that outperform the assignments reported in the literature even when converters are used. The proposed on-line scheme called "Round-Robin" assignment outperforms previously proposed strategies such as first-fit and random assignment schemes. …

Metal–Insulator–Semiconductor Electrostatics Of Carbon Nanotubes, Jing Guo, Sebastien Goasguen, Mark S. Lundstrom, Supriyo Datta

Department of Electrical and Computer Engineering Faculty Publications

Carbon nanotube metal-insulator-semiconductor capacitors are examined theoretically. For the densely packed array of nanotubes on a planar insulator, the capacitance per tube is reduced due to the screening of the charge on the gate plane by the neighboring nanotubes. In contrast to the silicon metal-oxide-semiconductor capacitors, the calculated C-VC-V curves reflect the local peaks of the one-dimensional density-of-states in the nanotube. This effect provides the possibility to use C-VC-V measurements to diagnose the electronic structures of nanotubes. Results of the electrostatic calculations can also be applied to estimate the upper-limit on-current of carbon nanotube field-effect transistors.

Performance Projections For Ballistic Carbon Nanotube Field-Effect Transistors, Jing Guo, Mark S. Lundstrom, Supriyo Datta

Department of Electrical and Computer Engineering Faculty Publications

The performance limits of carbon nanotube field-effect transistors (CNTFETs) are examined theoretically by extending a one-dimensional treatment used for silicon metal-oxide-semiconductor field-effect transistors (MOSFETs). Compared to ballistic MOSFETs, ballistic CNTFETs show similar I-VI-V characteristics but the channel conductance is quantized. For low-voltage, digital applications, the CNTFET with a planar gate geometry provides an on-current that is comparable to that expected for a ballistic MOSFET. Significantly better performance, however, could be achieved with high gate capacitance structures. Because the computed performance limits greatly exceed the performance of recently reported CNTFETs, there is considerable opportunity for progress in device performance.

A Drift-Diffusion Equation For Ballistic Transport In Nanoscale Metal-Oxide-Semiconductor Field Effect Transistors, Jung-Hoon Rhew, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The performance limits of carbon nanotube field-effect transistors ~CNTFETs! are examined theoretically by extending a one-dimensional treatment used for silicon metal–oxide– semiconductor field-effect transistors ~MOSFETs!. Compared to ballistic MOSFETs, ballistic CNTFETs show similar I –V characteristics but the channel conductance is quantized. For low-voltage, digital applications, the CNTFET with a planar gate geometry provides an on-current that is comparable to that expected for a ballistic MOSFET. Significantly better performance, however, could be achieved with high gate capacitance structures. Because the computed performance limits greatly exceed the performance of recently reported CNTFETs, there is considerable opportunity for progress in device performance.

Simulating Quantum Transport In Nanoscale Mosfets: Real Vs. Mode Space Approaches, Rajesh Venugopal, Z. Ren, Supriyo Datta, Mark S. Lundstrom, D. Jovanovic

Department of Electrical and Computer Engineering Faculty Publications

The performance limits of carbon nanotube field-effect transistors (CNTFETs) are examined theoretically by extending a one-dimensional treatment used for silicon metal–oxide–semiconductor field-effect transistors (MOSFETs). Compared to ballistic MOSFETs, ballistic CNTFETs show similar I–VI–V characteristics but the channel conductance is quantized. For low-voltage, digital applications, the CNTFET with a planar gate geometry provides an on-current that is comparable to that expected for a ballistic MOSFET. Significantly better performance, however, could be achieved with high gate capacitance structures. Because the computed performance limits greatly exceed the performance of recently reported CNTFETs, there is considerable opportunity for progress in device performance.

Video Indexing And Retrieval Techniques Using Novel Approaches To Video Segmentation, Characterization, And Similarity Matching, Waleed Ezzat Farag

Computer Science Theses & Dissertations

Multimedia applications are rapidly spread at an ever-increasing rate introducing a number of challenging problems at the hands of the research community, The most significant and influential problem, among them, is the effective access to stored data. In spite of the popularity of keyword-based search technique in alphanumeric databases, it is inadequate for use with multimedia data due to their unstructured nature. On the other hand, a number of content-based access techniques have been developed in the context of image indexing and retrieval; meanwhile video retrieval systems start to gain wide attention, This work proposes a number of techniques constituting …

An Algebraic Algorithm For Nonuniformity Correction In Focal-Plane Arrays, Bradley M. Ratliff, Majeed M. Hayat, Russell C. Hardie

Electrical and Computer Engineering Faculty Research and Publications

A scene-based algorithm is developed to compensate for bias nonuniformity in focal-plane arrays. Nonuniformity can be extremely problematic, especially for mid- to far-infrared imaging systems. The technique is based on use of estimates of interframe subpixel shifts in an image sequence, in conjunction with a linear-interpolation model for the motion, to extract information on the bias nonuniformity algebraically. The performance of the proposed algorithm is analyzed by using real infrared and simulated data. One advantage of this technique is its simplicity; it requires relatively few frames to generate an effective correction matrix, thereby permitting the execution of frequent on-the-fly nonuniformity …

Maximum-Likelihood Image Estimation Using Photon-Correlated Beams, Majeed M. Hayat, Muhammad Sajjad Abdullah, Adel Joobeur, Bahaa E.A. Saleh

Electrical and Computer Engineering Faculty Research and Publications

A theory is presented addressing the fundamental limits of image estimation in a setup that uses two photon-correlated beams. These beams have the property that their photon arrivals, as a point process, are ideally synchronized in time and space. The true image represents the spatial distribution of the optical transmittance (or reflectance) of an object. In this setup, one beam is used to probe the image while the other is used as a reference providing additional information on the actual number of photons impinging on the object. This additional information is exploited to reduce the effect of quantum noise associated …

Symmetrically Coated Pellicle Beam Splitters For Dual Quarter-Wave Retardation In Reflection And Transmission, Rasheed M.A. Azzam, Fadi A. Mahmoud

Electrical Engineering Faculty Publications

A trilayer pellicle that consists of a high-index center layer that is symmetrically coated on both sides by a low-index film can be designed to produce differential reflection and transmission phase shifts of ∓90° at oblique incidence and equal throughput for the p and the s polarizations. Such a device splits a beam of incident linearly polarized light into two orthogonal circularly polarized components that travel in well-separated angular directions. Examples of infrared dual quarter-wave retarders that use a symmetrically coated Ge pellicle at 77° angle of incidence are presented. A 50–50% splitter requires a symmetric pellicle with at least …

Angular Range For Reflection Of P-Polarized Light At The Surface Of An Absorbing Medium With Reflectance Below That At Normal Incidence, R. M.A. Azzam, Ericson E. Ugbo

Electrical Engineering Faculty Publications

The range of incidence angle, 0 < φ < φ_e, over which p-polarized light is reflected at interfaces between transparent and absorbing media with reflectance below that at normal incidence is determined. Contours of constant φ_e in the complex plane of the relative dielectric constant ε are presented. A method for determining the real and imaginary parts of the complex refractive index, ε^1/2 = n + jk, which is based on measuring φ_e and the pseudo-Brewster angle φ_pB, is viable in the domain of fractional optical constants, n, k < 1.

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

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

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 …

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.

Gain-Bandwidth Characteristics Of Thin Avalanche Photodiodes, Majeed M. Hayat, Oh-Hyun Kwon, Yi Pan, Paul P. Sotirelis, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

The frequency-response characteristics of avalanche photodiodes (APDs) with thin multiplication layers are investigated by means of a recurrence technique that incorporates the history dependence of ionization coefficients. In addition, to characterize the autocorrelation function of the impulse response, new recurrence equations are derived and solved using a parallel computer. The mean frequency response and the gain-bandwidth product are computed and a simple model for the dependence of the gain-bandwidth product on the multiplication-layer width is set forth for GaAs, InP, Al/sub 0.2/Ga/sub 0.8/As, and In/sub 0.52/Al/sub 0.48/As APDs. It is shown that the dead-space effect leads to a reduction (up …

Modeling, Fabrication, And Optimization Of Niobium Cavities, Robert A. Schill Jr., Mohamed Trabia, Yitung Chen

Transmutation Sciences Materials (TRP)

All technologies for the transmutation of nuclear waste require a large source of neutrons. One of the principal methods of generating these neutrons is by using a particle accelerator to bombard a heavy metal target. One of the more promising designs for particle accelerators for transmutation systems is the Superconducting Radio Frequency (RF) high-current linear accelerator (linac). The power supplies for these systems have three major components: niobium cavities, power couplers, and cryomodules. This research project will develop models to predict the behavior and performance of the niobium cavities, which will then be used to design and optimize the superconducting …

Kalman Filtering With State Equality Constraints, Daniel J. Simon, Tien Li Chia

Electrical and Computer Engineering Faculty Publications

Kalman filters are commonly used to estimate the states of a dynamic system. However, in the application of Kalman filters there is often known model or signal information that is either ignored or dealt with heuristically. For instance, constraints on state values (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. A rigorous analytic method of incorporating state equality constraints in the Kalman filter is developed. The constraints may be time varying. At each time step the unconstrained Kalman filter solution is projected onto the state …

A Distributed Discrete-Time Neural Network Architecture For Pattern Allocation And Control, A.T. Chronopoulos, Jagannathan Sarangapani

Computer Science Faculty Research & Creative Works

No abstract provided.

Node Splitting Algorithms In Tree-Structured High-Dimensional Indexes For Similarity Search, Yongjian Fu, Jui Che Teng, S. R. Subramanya

Computer Science Faculty Research & Creative Works

Content-based searches and retrievals in multimedia and image databases use high-dimensional indexing structures for organizing the features of the objects. Most of those index structures are tree-structured whose nodes have a limit on the number of entries describing the subtrees rooted at those nodes. When index trees are built by repeated insertion of entries, nodes need to be split and the tree balanced accordingly. Node-splitting algorithms eventually determine the final structure of the tree which will have a profound effect on the search performance. This paper presents a comparative study of several node splitting algorithms for a typical high-dimensional indexing …

Efficient Algorithms For Creation Of Linearly-Independent Decision Diagrams And Their Mapping To Regular Layouts, Marek Perkowski, Bogdan Jaroslaw Falkowski, Malgorzata Chrzanowska-Jeske, Rolf Dreschler

Electrical and Computer Engineering Faculty Publications and Presentations

A new kind of a decision diagrams are presented: its nodes correspond to all types of nonsingular expansions for groups of input variables, in particular pairs. The diagrams are called the Linearly Independent (LI) Decision Diagrams (LI DDs). There are 840 nonsigular expansions for a pair of variables, thus 840 different types of nodes in the tree. Therefore, the number of nodes in such (exact) diagrams is usually much smaller than the number of nodes in the well-known Kronecker diagrams (which have only single-variable Shannon, Positive Davio, and Negative Davio expansions in nodes). It is usually much smaller than 1/3 …

Term Trees In Application To An Effective And Efficient Atpg For And–Exor And And–Or Circuits, Lech Jozwiak, Aleksander Ślusarczyk, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

A compact data representation, in which the typically required operations are performed rapidly, and effective and efficient algorithms that work on these representations are the essential elements of a successful CAD tool. The objective of this paper is to present a new data representation—term trees (TTs)—and to discuss its application for an effective and efficient structural automatic test-pattern generation (ATPG). Term trees are decision diagrams similar to BDDs that are particularly suitable for structure representation of AND–OR and AND–EXOR circuits. In the paper, a flexible algorithm for minimum term-tree construction is discussed and an effective and efficient algorithm for ATPG …

Multiple-Valued Quantum Logic Synthesis, Marek Perkowski, Anas Al-Rabadi, Pawel Kerttopf

Electrical and Computer Engineering Faculty Publications and Presentations

This paper asks the question: is logic synthesis for quantum computers a practical research subject?

We would like to assume that any two quantum wires can interact, but we are limited by the realization constraints. Structure of atomic bonds in the molecule determines neighborhoods in the circuit. This is similar to restricted routing in FPGA layout - link between logic and layout synthesis known from CMOS design now appears in quantum. Below we are interested only in the so-called “permutation circuits” - their unitary quantum matrices are permutation matrices.

Generalized Inclusive Forms — New Canonical Reed-Muller Forms Including Minimum Esops, Marek Perkowski, Alan Mishchenko, Malgorzata Chzanowka-Jeske

Electrical and Computer Engineering Faculty Publications and Presentations

Reed-Muller (AND/EXOR) expansions play an important role in logic synthesis and circuit design by producing economical and highly-testable implementations of Boolean functions [3–6]. The range of Reed-Muller expansions include canonical forms, i.e. expansions that create unique representations of a Boolean function. Several large families of canonical forms: fixed polarity Reed-Muller forms (FPRMs), generalized Reed-Muller forms (GRMs), Kronecker forms (KROs), and pseudo- Kronecker forms (PKROs), referred to as the Green/Sasao hierarchy, have been described [7–9]. (See Fig. 1 for a settheoretic relationship between these families.)

Nitriding Of Titanium By Inductively Coupled Plasma, Abdul Hakim Hashim

Student Works (2000-2009)

A RF planar coil inductively coupled plasma syslem (ICP) is used in this project to nitride a commercially pure titanium substrate. The system is powered by a 600 W, 13.56 MHz, 50 Ω RF generator. The impedance matching is achieved by using an air­-core step-down transformer and a tunable vacuum capacitor. The electrical discharge characteristics of argon and argon-nitrogen admixture plasmas are investigated. Coil current, ion density and RF power transferred in the plasma at different pressure are studied. Nitriding of titanium using the system is found to be able to produce θ-TiN, ε-Ti2N and α-Ti(N) layers, as confirmed by …