Engineering Commons^™

Logic Functions From Three-Terminal Quantum Resistor Networks For Electron Wave Computing, Cheng-Hsiao Wu, Diwakar Ramamurthy

Electrical and Computer Engineering Faculty Research & Creative Works

Electron transmission characteristics through a generalized three-terminal clean Aharonov-Bohm ring is investigated with an arbitrary terminal configuration. This three-terminal ring is shown to be the most basic quantum resistor network that is suitable for electron wave computing, as we demonstrate in this work. There are four basic classes of three-terminal rings. The scaling relation in each class is deduced. Thus the transmission characteristics in each class are valid from an atomic-scale-sized ring to a mesoscopic-scale-sized one, limited only by the electron phase-breaking length. The Buttiker symmetry rule is essential when searching for basic logic functions. Logic functions such as IF-THEN, …

Stability Analysis Of A Dc Power Electronics Based Distribution System, Scott D. Sudhoff, Steven Pekarek, S. F. Glover, S. H. Zak, E. Zivi, J. D. Sauer, D. E. Delisle

Electrical and Computer Engineering Faculty Research & Creative Works

This paper illustrates the application of the generalized immittance space approach to the analysis of multi-bus interconnected power electronics-based power distribution system. The paper sets forth the basic classifications of power converters in regard to stability analysis, a set of network reduction transformations, and illustrates the use of these reductions in order to analyze the stability of a zonal dc distribution system. Copyright © 2002 Society of Automotive Engineers, Inc.

Robust Generalised Predictive Control - An Optimal Design For Uncertain Systems, Thomas O'Mahony

Theses

One of the more popular model predictive control approaches, of late, is the generalised predictive controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority over its predecessors, its simplicity and its control acumen. However, since GPC is based on a mathematical model of the process, significant deterioration in performance or even closed-loop instability may arise due to the inevitable discrepancies that arise between the model and the true system. To ensure that the loop stability is not compromised and an adequate level of …

Counterexample Of A Claim Pertaining To The Synthesis Of A Recurrent Neural Network, Xindi Cai, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Recurrent neural networks have received much attention due to their nonlinear dynamic behavior. One such type of dynamic behavior is that of setting a fixed stable state. This paper shows a counterexample to the claim of A.N. Michel et al. (IEEE Control Systems Magazine, vol. 15, pp. 52-65, Jun. 1995), that "sparse constraints on the interconnecting structure for a given neural network are usually expressed as constraints which require that pre-determined elements of T [a real n×n matrix acting on a real n-vector valued function] be zero", for the synthesis of sparsely interconnected recurrent neural networks.

Design And Analysis Of Class Ab Rf Power Amplifier For Wireless Communication Applications, Mohamed El-Dakroury

Retrospective Theses and Dissertations

The Power Amplifier is the most power-consulting block among the building blocks of RF transceivers. It is still a difficult problem to design power amplifiers, especially for linear, low voltage operation. Until now power amplifiers for wireless applications is being produced almost in GaAs processes with some exceptions in LDMOS, Si BJT, and SiGe HBT. The submicron CMOS processes for power amplifiers are under research focus since CMOS offers integration for power amplifier with rest of the transceivers blocks due to its high yield. Also CMOS process is cheap.

This thesis report details the design process of a class AB …

High Frequency Communication System Modeling And Performance Enhancement, Employing Novel Adaptive Dsp Techniques, Murad M. Qahwash

Retrospective Theses and Dissertations

High Frequency (HF) communication has been shown to be a useful communication technique from the very beginning of World War I and it accelerated during World War II. This is attributed to its simplicity, ability to provide near globe connectivity at low power without repeaters, moderate cost, and ease of proliferation [1]. In fact, the HF communication system utilizes the ionosphere [2][3][4] to refract the skywave signals to a distant receiver. This ionospheric channel has some disadvantages. First, it is a non-stationary channel as the HF frequency propagation is a function of the sun spot activities, solar winds, and diurnal …

Oxidation-Induced Stacking Fault In (100) And (111) Silicon Wafers, Mei Keat Liang

Student Works (2000-2009)

Oxidation-induced stacking fault (OISF) dimension and density change on (100) and (111) wafers, as a result of repeated preferential etching were studied using AFM. optical microscope and angular polishing techniques. Density on (100) and (111) wafers is independent of surface removal up to 3.0µm. This indicates the single layer nature of OISF formed from the sand blasted wafer. Besides having higher density, OISFs from (100) wafer were longer than OISF from (111) wafer. OISF width increases linearly with surface removal however the length does not change significantly with surface removal. ln the OISF normal depth studies using angular polishing technique, …

Hybrid Sr Arq Scheme Using Trellis Coded Modulation For Point-To-Multipoint Communication Over Nonstationary Channels, Necmi̇ Taşpinar

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a type-I hybrid SR ARQ scheme using trellis coded modulation (TCM) for point-to-multipoint communication was analyzed on nonstationary broadcast channels where the channel bit error rate (BER) varies over time. A nonstationary channel is modelled as a two-state Markov chain. In the numerical calculations, it is found that, for a given p_{1} and \bar \varepsilon , the values of the average burst length \bar b have a very small influence on the throughput. Numerical results show that the throughput is better for values between 10 ^{-6} and 10 ^{-4}of average bit error rate \bar \varepsilon if the …

Stability Analysis Of A Closed-Loop Control For A Pulse Width Modulated Dc Motor Drive, Fatma Gürbüz, Eyüp Akpinar

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the effect of the variation of amplitude and the chopping period of a PWM signal on the stability of a closed-loop control for a DC motor drive is investigated. First, the entire system is formulated as a Linear Quadratic (LQ) tracker with output feedback [1]. Then, stability analysis for the varying amplitude and the varying chopping period is carried out by the methods of root locus and the Jury test. Finally, stability limits obtained from a root locus and Jury test are checked by the simulation of the system in MATLAB.

Ternary And Quaternary Logic To Binary Bit Conversion Cmos Integrated Circuit Design Using Multiple Input Floating Gate Mosfets, Harish N. Venkata

LSU Master's Theses

Multiple-input floating gate MOSFETs and floating gate potential diagrams have been used for conversion of ternary-valued input and quaternary-valued input into corresponding binary-valued output in CMOS integrated circuit design environment. The method is demonstrated through the design of a circuit for conversion of ternary inputs 00 to -1-1 (decimal 0 to -4) and 00 to 11 (decimal 0 to +4) into the corresponding binary bits and for conversion of quaternary inputs (decimal 0 to 3) into the corresponding binary bits (binary 00 to 11) in a standard 1.5 mm digital CMOS technology. The physical design of the circuits is simulated …

Mobile Home Security With Gprs, Duy Nguyen

Theses : Honours

This thesis presents the results of an honours project on the development of a security system for use on mobile devices. Mobile Home Security (MHS) is a prototype system that aimed to fully investigate a potential use of the wireless high-speed technology General Packet Radio Service (GPRS) in transmitting video from a static location. This thesis Mobile Home Security with GPRS describes in detail the design and developmental stages for the system. The research focused on the sending of video from a security capture device over a high speed radio network. The first stage of the research involved the design …

Acceleration Element For Femtosecond Electron Pulse Compression, Bao-Liang Qian, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

An acceleration element is proposed for compressing the electron pulse duration in a femtosecond photoelectron gun. The element is a compact metal cavity with curved-shaped walls. An external voltage is applied to the cavity where a special electric field forms in such a way that the slow electrons in the electron pulse front are accelerated more than the fast electrons, and consequently the electron pulse duration will be compressed. The distribution of the electric field inside the acceleration cavity is analyzed for the geometry of the cavity. The electron dynamics in this acceleration cavity is also investigated numerically. Numerical results …

121.6 Nm Radiation Source For Advanced Lithography, Jianxun Yan, Ashraf El-Dakrouri, Mounir Laroussi, Mool C. Gupta

Electrical & Computer Engineering Faculty Publications

A vacuum ultraviolet (VUV) light source based on a high-pressure cylindrical dielectric barrier discharge (DBD) has been developed. Intense and spectrally clean Lyman-α line at 121.6 nm was obtained by operating a DBD discharge in neon with a small admixture of hydrogen. The spectrum, optical power, stability, and efficiency of the source were measured. The influence of the gas mixture and total gas pressure on the VUV intensity has been investigated. Maximum optical power of 3.2 W and spectral width 0.03 nm was achieved. Power stability of 2% for 100 h of operation has also been obtained. The newly developed …

High-Efficiency Solar Cells Based On Cu(Inal)Se[Sub 2] Thin Films, S. Marsillac, P. D. Paulson, M. W. Haimbodi, R. W. Birkmire, W. N. Shafarman

Electrical & Computer Engineering Faculty Publications

A Cu(InAl)Se₂solar cell with 16.9% efficiency is demonstrated using a Cu(InAl)Se₂thin film deposited by four-source elemental evaporation and a device structure of glass/Mo/Cu(InAl)Se₂/CdS/ZnO/indium tin oxide/(Ni/Algrid)/MgF₂. A key to high efficiency is improved adhesion between the Cu(InAl)Se₂ and the Mo back contact layer, provided by a 5-nm-thick Ga interlayer, which enabled the Cu(InAl)Se₂ to be deposited at a 530 °C substrate temperature. Film and device properties are compared to Cu(InGa)Se₂ with the same band gap of 1.16 eV. The solar cells have similar behavior, with performance limited by recombination through …

Modeling Of Electrofusion Coils For Performance Optimization, Steve Farmer, Robert A. Sims

Journal of the Arkansas Academy of Science

Modeling physical parameters provides a virtual design environment allowing the confirmation and optimization of electrofusion characteristics. Finite element incorporate physical parameters and their interactions along common boundaries defined within a model geometry. The electrofusion of polymeric piping is a widely accepted means of assembling piping systems with zero-leakage integrity. The key parameters in the fusion process are the coil resistance, the current passing through the coil and the time the current is applied. Modeling the coil and applying current to the model is accomplished using the MATLABpartial differential equations (PDE) toolbox. This paper presents the method of modeling and the …

Co-Polymers Of Furan With Pyrrole Or Thiophene: A Synthetic Study, Rose M. Mcconnell, Walter E. Godwin, Susan E. Baker, Kenya Powell, Martha Baskett, Amy Morara, Xiadong Ma

Journal of the Arkansas Academy of Science

The use of conductive polymers as a substitute for metallic conductors and semiconductors has attracted much attention in the literature. In particular, aromatic heterocyclic polymers constitute an important class since they possess chemical and electrical stability in both the oxidized (doped) and neutral (undoped) state. Doping a polymer allows one to vary its electrical, mechanical, optical, and thermal properties. The properties of these polymers are promising for their many technological uses such as antistatic coatings, solar cells, and electronic devises. Polyfuran is among the least common heterocyclic polymers. Polyfuran has been reported to be much less stable that either polypyrrole …

Mechanism For Membrane Electroporation Irreversibility Under High-Intensity, Ultrashort Electrical Pulse Conditions, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), …

Electron Pulse Broadening Due To Space Charge Effects In A Photoelectron Gun For Electron Diffraction And Streak Camera Systems, Bao-Liang Qian, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The electron pulse broadening and energy spread, caused by space charge effects, in a photoelectron gun are studied analytically using a fluid model. The model is applicable in both the photocathode-to-mesh region and the postanode electron drift region. It is found that space charge effects in the photocathode-to-mesh region are generally unimportant even for subpicosecond pulses. However, because of the long drift distance, electron pulse broadening due to space charge effects in the drift region is usually significant and could be much larger than the initial electron pulse duration for a subpicosecond electron pulse. Space charge effects can also lead …

Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

A nonlithographic approach to produce self-assembled spatially separated Si structures for nanoelectronic applications was developed, employing the metal-induced silicon growth. Densely packed Si whiskers, 500–800 nm thick and up to 2500 nm long, were obtained by magnetron sputtering of Si on a 25 nm thick Ni prelayer at 575 °C. The nucleation of the NiSi2 compound at the Ni–Si interface followed by the Si heteroepitaxy on the lattice-matched NiSi2 is suggested to be the driving force for the whisker formation.

Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Dermot Coyle Professor

Conference papers

The velocity-based local model (LM) network is a novel modelling approach that overcomes the lack of interpretability associated with the conventional LM network technique. The global dynamics of the nonlinear network are directly related to the underlying sub-model dynamics. Thus, the velocity-based network is ideally suited to the development of local controller (LC) networks. Furthermore, the local models are continuous-time, velocity-based and linear, providing continuity with established linear theory. To date, research has focused on the continuous-time version of the velocity-based network. The application of digital computer is widely popular in the field of control and, therefore, this paper develops …

A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor

Conference papers

The basic PID controllers have difficulty in dealing with problems that appear in complex non-linear processes. This paper presents a practical non-linear PID controller that deals with these non-linear difficulties. It utilises a local model (LM) network, which combines a set of local models within an artificial neural network structure, to adaptively characterise the process non-linearity. Then a local controller network is formulated through a gating system deduced from the LMN to handle the non-linearity. A continuous stirred tank reaction (CSTR) case study illustrates the practicality of this method in the modelling and control of non-linear processes. PID controllers are …

Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer

Conference papers

An extensive though scattered literature exists on the estimation of time delays in signal processing applications. However, it is possible to identify themes that are common to many of the available techniques. The intention of this paper is to provide a framework against which the literature may be viewed. In addition, original work on gradient based time delay estimation is described.

Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer

Conference papers

This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI controllers whose parameters are specified using appropriate tuning rules. The gain margin and phase margin of the compensated system, as the ratio of time delay to time constant of the process varies, are calculated for each tuning rule and an expert system is used to recommend a tuning rule for user defined requirements.

Regenerative Magnet Load Power Supply With Utility Friendly Operations, M. Sri Balaji, S. P. Das, Gopal Dubey, Malabika Basu

Conference papers

In the present paper, a utility friendly regenerative magnet load power supply has been proposed which can tolerate supply voltage dips and long duration sags or undervoltages and maintains unity input power factor under all operating conditions. The harmonics injected into the utility are much less and the total harmonic distortion (THD) complies with IEEE standards. Unity power factor at the input is maintained by using a synchronous link converter (SLC) as the front-end AC to DC converter with regenerative capability. The two-quadrant chopper in the second stage operates in a constant frequency current control mode and takes care of …

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 …

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.

Adaptive Radio Resource Management For 2.5g Cellular Networks, Ken Murray

Theses

Recent years have seen a dramatic increase in demand for mobile communication services and with the introduction of 2.5G services such as general packet radio service, this trend is expected to increase further. These new services will introduce highly dynamic tele-traffic variations due to the inherent variability in resource usage of the new data services. The net effect will be considerable increase in load on the available radio resources. The currently employed fixed channel allocation scheme lacks the flexibility to support such traffic variations. A plethora of dynamic channel allocation schemes have been proposed in the past in an effort …