Engineering Commons^™

An Experimental Model Of Ball Lightning, Madras Parameswaran Sriram

Masters Theses

A form of ball lightning was generated in the laboratory. Plasma spheres several centimeters in diameter were produced in atmospheric pressure air. These spheres persisted up to ½ a second after power turn –off. A mathematical model was derived that predicts the observed lifetime. The theory predicts that the sphere lifetime should scale as the radius squared, which means large spheres should exist for many seconds. We also generated ball lightning in a zero gravity environment. The object was to eliminate convection, which had been observed to reduce the size of a ball generated by a two – dimensional electric …

A Characteristic Study Of The Atmospheric Pressure Nonthermal Resistive Barrier Plasma Discharge For Biological Decontamination, Magesh Thiyagarajan

Masters Theses

Steady-state atmospheric pressure nonthermal plasmas can splendidly debilitate bacteria in liquids, gases and on surfaces, as well as can disintegrate hazardous chemicals. The nonthermal gas discharge at atmospheric pressure, such as resistive barrier discharge is investigated for low temperature sterilization purposes. In specific, exploring and understanding the hidden secrets of the plasma sterilization mechanisms and the intensification of the main microbial reduction pathways are the objectives of the research.

A dual-mode steady-state atmospheric pressure resistive barrier ionized gas (plasma) generator has been designed and developed to meet the environmental health and federally mandated safety standards. Electrical, chemical, optical, and biological …

Multidimensional Digital Signal Estimation Using Kalman's Theory For Computer-Aided Applications, Ivan E. Villalon-Turrubiates, Jose A. Andrade-Lucio, Oscar G. Ibarra-Manzano

Iván Esteban Villalón Turrubiates

In this paper, we analyze the Multidimensional Kalman Algorithm to estimate a signal corrupted by white Gaussian noise. Because the theory provide a good solution to the problem with a large number of signals, we developed an algorithm for three-dimensional Kalman filtering applied to the positioning problem (latitude, altitude and longitude) of a stationary object based on GPS signals. This application was selected because the incoming signals of the GPS encounters some noise on its way to the receiver, which is originated from different types of sources, the consequences are that the received signals are noisy, therefore inaccurate. The signals …

Experimental Studies Of Generalized Neuron Based Power System Stabilizer, D. K. Chaturvedi, O. P. Malik, P. K. Kalra

D. K. Chaturvedi Dr.

Artificial neural networks (ANNs) can be used as intelligent controllers to control nonlinear, dynamic systems through learning, which can easily accommodate the nonlinearities and time dependencies. However, they require large training time and large number of neurons to deal with complex problems. To overcome these drawbacks, a generalized neuron (GN) has been developed that requires much smaller training data and shorter training time. Taking benefit of these characteristics of the GN, a new power system stabilizer (PSS) is proposed. Results show that the proposed GN-based PSS can provide a consistently good dynamic performance of the system over a wide range …

Determination And Control Of The Impact Of The Manoeuvres Of The Compensation Batteries On The Over Voltages And The Transient Over Currents, Hocine . Labar

Boukhemis Chetate

No abstract provided.

Fuzzy Modeling Of Electromagnetic Emissions From Portable Electronic Devices Onboard Commercial Aircraft, Madiha Jamil Jafri

Electrical & Computer Engineering Theses & Dissertations

The use of Portable Electronic Devices (PEDs) is prohibited during take-off and landing of an aircraft because PEDs may emit signals that can interfere with the aircraft's navigation and communication systems. The electromagnetic interference (EMI) on the aircraft's electronics due to PEDs emissions is examined for Boeing 737 and 747 aircraft. This work, funded by the NASA Graduate Researchers Program, uses Interference Path Loss (IPL) data, collected by researchers from NASA Langley Research Center, Eagles Wings Inc. and United Airlines on several out-of-service United B737 and B747 airplanes.

B737 and B747 IPL data has been analyzed using a graphical analysis …

Real-Time Measurements On The Effects Of Ultra-Short High Voltage Pulses On Hl-60 Cells, Michalis C. Artemiou

Electrical & Computer Engineering Theses & Dissertations

The application of high voltage microsecond pulses that are above a critical value, to biological cells, has been shown to cause electroporation (Neumann, 1989). In addition, ultra-short pulses of several tens to hundreds of nanoseconds duration have been recently shown to affect intracellular structures without disturbing the plasma membrane (Schoenbach, 2001). However, such ultra-short intense pulses are expected to cause deformation of cells due to Maxwell stresses. This deformation was studied by means of an imaging technique with 10 ns temporal resolution on HL-60 cells. The imaging system consists of an inverted microscope where a spark light source was used …

Modeling Nerve Electro-Stimulation In The Nanosecond Regime, Feng Chen

Electrical & Computer Engineering Theses & Dissertations

Numerical simulations of electrical stimulation of frog gastrocnemius muscles have been carried out for pulse durations in the nanosecond regime. There are a number of potential advantages in using ultra-short pulses for neural stimulation, and no previous electro-stimulation work in the sub-microsecond regime has been reported. A timedependent, three-dimensional analysis model was developed and implemented for three distinct situations: (i) direct stimulation via electrode contact, (ii) indirect excitation based on electrodes immersed in a saline-filled bath, and (iii) remote electromagnetic stimulation through vacuum. The simulations yielded strength-dm ation (S-D) curves with pulse durations as short as 5 ns. Good agreement …

Investigation Into The Current Statistical Distribution For Oxide Breakdown Versus The Oxide Thickness Used In Integrated Circuit Manufacture, Eoin James O Driscoll

Theses

A critical aspect of integrated circuit manufacturing is the reliability of the components, in particular the gate oxide of transistors and capacitors. Accelerated stress tests are used for reliability predictions of gate oxides. There are two statistical distributions, which can be applied to stress test failure data, namely the Lognormal or the Weibull distributions. The failure data can fit each distribution equally well. However the use of either distribution will give vastly different lifetime predictions and their correct use is crucial for accurate lifetime prediction. A statistical based test, developed with Monte Carlo data, which is designed to decide if …

Implementing Institute Of Electrical And Electronics Engineers (Ieee) 802.11 Standard Medium Access Control Protocol For Wireless Local Area Networks (Lans) On A Laboratory Hardware Prototype, Joshua D. Green

Theses and Dissertations

Wireless Local Area Networks (LANs) are extremely convenient, flexible, and easy to deploy. All LANs in which multiple hosts must access the same medium use a Medium Access Control (MAC) protocol to coordinate channel access. The MAC is part of the Data Link Layer of the Open Systems Interconnection (OSI) Reference Model. One MAC protocol in extensive use today is the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. Since IEEE 802.11 devices are so prevalent in today s world, many researcher are exploring modifications and enhancements to the protocol. There are several well developed analytical and simulation models …

Simulation Of Hot Electron And Quantum Effects In Algan/Gan Heterostructure Field Effect Transistors, N. Braga, R. Mickevicius, R. Gaska, H. Xu, M. S. Shur, M. Asif Khan, Grigory Simin, J. Yang

Faculty Publications

We report on simulations of electrical characteristics of AlGaN/(InGaN)/GaN heterostructurefield effect transistors with quantum and hot electroneffects taken into account. Polarization charges lead to quantum confinement of electrons in the channel and to the formation of two-dimensional electron gas. The electron quantization leads to the spread of the electronwave function into the barrier and bulk but does not have significant impact on dc electrical characteristics.Hot electrons play an important part in the charge transport by spilling over into the bulk GaN where they are captured by traps. This leads to negative differential conductivity, which is also observed experimentally. The simulation …

Performance Evaluation Of Communication Systems With Transmit Diversity, Chunjun Gao

Dissertations

Transmit diversity is a key technique to combat fading with multiple transmit antennae for next-generation wireless communication systems. Space-time block code (STBC) is a main component of this technique. This dissertation consists of four parts: the first three discuss performance evaluation of STBCs in various circumstances, the fourth outlines a novel differential scheme with full transmit diversity.

In the first part, closed-form expressions for the bit error rate (BER) are derived for STBC based on Alamouti's scheme and utilizing M-ary phase shift keying (MPSK) modulation. The analysis is carried out for a slow, flat Rayleigh fading channel with coherent detection …

Multi-Rate Access Schemes And Successive Interference Cancellation For Wireless Multimedia Mc-Cdma Communications, Mizhou Tan

Dissertations

To catch up with the fast changes of the information challenges, providing multimedia services has become a very important requirement for future wireless communications. A proper system, capable of supporting multi-rate transmissions as well as handling high quality of service (QoS) requirements in hostile wireless communication environments, should be sought. Multi-carrier CDMA (MC-CDMA), a combination of multi-carrier modulation (MCM) and direct-sequence CDMA (DS-CDMA), appears to be one of the most elegant solutions. In this dissertation, four multi-rate access schemes, termed uncoded fixed spreading length (UFSL), coded fixed spreading length (CFSL), multi-code fixed spreading length (MFSL) and variable spreading length (VSL), …

Providing Guaranteed Qos In The Hose-Modeled Vpn, Dong Wei

Dissertations

With the development of the Internet, Internet service providers (ISPs) are required to offer revenue-generating and value-added services instead of only providing bandwidth and access services. Virtual Private Network (VPN) is one of the most important value-added services for ISPs.

The "classical" VPN service is provided by implementing layer 2 technologies, either Frame Relay (FR) or Asynchronous Transfer Mode (ATM). With FR or ATM, virtual circuits are created before data delivery. Since the bandwidth and buffers are reserved, the QoS requirements can be naturally guaranteed. In the past few years, layer 3 VPN technologies are widely deployed due to the …

Phase Noise Effects On Ofdm : Analysis And Mitigation, Songping Wu

Dissertations

Orthogonal frequency division multiplexing (OFDM) is a promising technique which has high spectrum efficiency and the robustness against channel frequency selectivity. One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant performance loss of OFDM. Therefore, phase noise effects on OFDM systems need to be analyzed and methods be provided to its mitigation.

Motivated by what have been proposed in the literature, the exact signal to interference plus noise ratio (SINR) is derived in this dissertation for arbitrary phase noise levels. In a multiple access environment with multiple …

Enhancing Qos Provisioning And Granularity In Next Generation Internet, Jie Yang

Dissertations

Next Generation IP technology has the potential to prevail, both in the access and in the core networks, as we are moving towards a multi-service, multimedia and high-speed networking environment. Many new applications, including the multimedia applications, have been developed and deployed, and demand Quality of Service (QoS) support from the Internet, in addition to the current best effort service. Therefore, QoS provisioning techniques in the Internet to guarantee some specific QoS parameters are more a requirement than a desire. Due to the large amount of data flows and bandwidth demand, as well as the various QoS requirements, scalability and …

Statistical Anomaly Denial Of Service And Reconnaissance Intrusion Detection, Zheng Zhang

Dissertations

This dissertation presents the architecture, methods and results of the Hierarchical Intrusion Detection Engine (HIDE) and the Reconnaissance Intrusion Detection System (RIDS); the former is denial-of-service (DoS) attack detector while the latter is a scan and probe (P&S) reconnaissance detector; both are statistical anomaly systems.

The HIDE is a packet-oriented, observation-window using, hierarchical, multi-tier, anomaly based network intrusion detection system, which monitors several network traffic parameters simultaneously, constructs a 64-bin probability density function (PDF) for each, statistically compares it to a reference PDF of normal behavior using a similarity metric, then combines the results into an anomaly status vector that …

Ad Hoc Network Security And Modeling With Stochastic Petri Nets, Congzhe Zhang

Dissertations

Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. These networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. Unlike the existing commercial wireless systems and fixed infrastructure networks, they do not rely on specialized routers for path discovery and traffic routing. Security is an important issue in such networks. Typically, mobile nodes are significantly more susceptible to physical attacks than their wired counterparts.

This research intends to investigate the ad hoc network routing security by proposing a performance …

Qos Provisioning In Multimedia Streaming, Hong Zhao

Dissertations

Multimedia consists of voice, video, and data. Sample applications include video conferencing, video on demand, distance learning, distributed games, and movies on demand. Providing Quality of Service (QoS) for multimedia streaming has been a difficult and challenging problem. When multimedia traffic is transported over a network, video traffic, though usually compressed/encoded for bandwidth reduction, still consumes most of the bandwidth. In addition, compressed video streams typically exhibit highly variable bit rates as well as long range dependence properties, thus exacerbating the challenge in meeting the stringent QoS requirements of multimedia streaming with high network utilization. Dynamic bandwidth allocation in which …

Ultra-Wideband Technology For Short-Range Wireless Communication, Li Zhao

Dissertations

The ultra-wideband (UWB) radio core idea is to open large amounts of spectrum to a variety of users with little mutual interference between them. While ultra-wideband is being championed by several commercial companies, this technology has not followed the conventional path where commercial interest is preceded by years of academic research. This work attempts to fill in some of the gap by studying fundamental properties of communications with impulse-based radio UWB signals. We study jam resistance and capacity of UWB. Jam resistance is analyzed for binary pulse position modulation (PPM) with the interference being modeled as correlated Gaussian. Closed-form expressions …

Transmission And Detection For Space-Time Block Coding And V-Blast Systems, Lei He

Dissertations

This dissertation focuses on topics of data transmission and detection of space -time block codes (STBC). The STBCs can be divided into two main categories, namely, the orthogonal space-time block codes (OSTBC) and the quasi-orthogonal space-time codes (Q-OSTBC). The space-time block coded systems from transceiver design perspective for both narrow-band and frequency selective wireless environment are studied. The dissertation also processes and studies a fast iterative detection scheme for a high-rate space-time transmission system, the V-BLAST system.

In Chapter 2, a new OSTBC scheme with full-rate and full-diversity, which can be used on QPSK transceiver systems with four transmit antennas …

Hybrid Routing And Bridging Strategies For Large Scale Mobile Ad Hoc Networks, Sheng Xu

Dissertations

Multi-hop packet radio networks (or mobile ad-hoc networks) are an ideal technology to establish "instant" communication infrastructure for military and civilian applications in which both hosts and routers are mobile. In this dissertation, a position-based/link-state hybrid, proactive routing protocol (Position-guided Sliding-window Routing - PSR) that provides for a flat, mobile ad-hoc routing architecture is described, analyzed and evaluated. PSR is based on the superposition of link-state and position-based routing, and it employs a simplified way of localizing routing overhead, without having to resort to complex, multiple-tier routing organization schemes. A set of geographic routing zones is defined for each node, …

A Statistical Ultra Wideband Indoor Channel Model And The Effects Of Antenna Directivity On Multipath Delay Spread And Path Loss In Ultra Wideband Indoor Channels, Jason Anthony Dabin

Theses

Ultra-wideband (UWB) indoor frequency domain channel measurements have been performed in the 2 GHz to 6 GHz frequency band using three different transmitter/receiver (Tx/Rx) antenna combination pairs. The effects of antenna directivity on path loss and multipath propagation in the channel were analyzed extensively for various omni-directional and directional antenna combinations. A statistical model of the path loss in the channel is presented, where the parameters in the model (i.e., path loss exponent and shadow fading statistics) are dependent on the particular Tx/Rx antenna combination. Time domain statistics of the channel (i.e., mean delay spread and RMS delay spread) are …

Study Of Design Tradeoffs Of Dram And Sram Memories, Using Hspice Computer Simulation, Bageshri Kale

Theses

Semiconductor random access memories are complex systems that can be described by performance parameters such as memory cycle time, access delays, storage capacity, bit packing density, chip area and retention time. In this thesis, tradeoffs between cycle time, chip area, and storage size as reflected by bit line capacitance (Cbl) were studied as a function of particular design variables: memory cell capacitance (Cc); CMOS flip-flop sense amplifier (SA) transistor sizes; and size of precharge (PC), and word line (WL) switches. Performance was optimized using circuit simulation software, HSPICE, to observe DRAM and SRAM waveforms. With TSMC 0.18 micron technology, minimum …

Si-Sio2 Interface Behavior In N-Mosfets With Screening Potential During High-Field Injection, Purushothaman Srinivasan

Theses

This work investigates the screening of hot carrier stress degradation in n-channel MOSFETs when the devices were exposed to plasma processing. Devices with various antenna ratios were subjected to current stress (both gate injection and substrate injection) while the source and drain terminals were reverse biased by a screening potential followed by hot carrier stress. It was observed that screening of the drain edge was effective for both gate injection and substrate injection at different screening potentials. The hot carrier lifetime is directly related to interface state density (Dit), measured by charge pumping method. The results suggest that hot electron …

Investigation Of Nanoporous Thin-Film Alumina Templates, Biswajit Das

Electrical & Computer Engineering Faculty Research

This paper presents the results of a systematic study of the fabrication of thin-film alumina templates on silicon and other substrates. Such templates are of significant interest for the low-cost implementation of semiconductor and metal nanostructure arrays. In addition, thin-film alumina templates on silicon have the potential for nanostructure integration with silicon electronics. Formation of thin-film alumina templates on silicon substrates was investigated under different fabrication conditions, and the dependence of pore morphology and pore formation rate on process parameters was evaluated. In addition, process conditions for improved pore size distribution and periodicity were determined. The template/silicon interface, important for …

The Technical Requirements For Multichannel Qam Rf Modulators, Ron D. Katznelson

Ron D. Katznelson

This paper addresses the technical requirements and implications for multichannel QAM RF modulators and upconverters and the factors that affect their proposed RF specifications. RF output power levels per channel, adjacent channel noise and broadband noise levels of such a class of multichannel modulators will be discussed. A spectral noise specification mask that is equivalent to that obtained from a combination of multiple identical masks of a standard single channel noise specifications based on power addition will be presented. The power back-off required for maintaining the proposed distortion mask levels as a function of the number of adjacent channels supported …

Eliminating Harmonics In A Cascaded H-Bridges Multilevel Inverter Using Resultant Theory, Symmetric Polynomials, And Power Sums, Keith Jeremy Mckenzie

Masters Theses

This thesis studies a multilevel converter with assumed equal dc sources. The multilevel fundamental switching scheme is used to control the needed power electronics switches. Also, a method is presented where switching angles are computed such that a desired fundamental sinusoidal voltage is produced while at the same time certain higher order harmonics are eliminated.

Using Fourier Series theory, the transcendental equations eliminating certain higher order harmonics were derived in terms of the switching angles. Furthermore, these transcendental equations were transformed into polynomial equations by making some simple changes of variables. Resultant theory was used to solve the polynomial equations. …

A 1.8 Ghz Lc-Voltage Controlled Oscillator Using On-Chip Inductors And Body Driven Varactors In Cmos 0.35 Μm Process, Lakshmipriya Seshan

Masters Theses

In an era dominated by the highly demanding wireless communication system, there is a great need for developing small, cheap, and low power RF sub-systems. This demand has lead to significant research on completely integrated transceiver systems. One of the great challenges in an integrated transceiver system is the frequency synthesizer. Frequency synthesizers are usually implemented using a phase locked loop (PLL) and low frequency highly stable crystal oscillator. The spectral purity of a synthesized carrier signal depends on the kind of Voltage Controlled Oscillator (VCO) used. Hence successful implementation of a low phase noise, completely integrated VCO in standard …

A Case For Including Harmonic Distortion Components In Docsis’ Rf Specifications For Non Aggregating Spurious Components, Ron D. Katznelson

Ron D. Katznelson

This note is submitted in support of a change in DOCSIS specifications for spurious performance. It shows that the impact of a proposed change is negligible and that the advantages far outweigh the perceived disadvantages of adopting such a change.