Engineering Commons^™

Development Of Hiv Model And Its Simulation, D. K. Chaturvedi, Pritam Singh, S. K. Gaur, D. S. Mishra

D. K. Chaturvedi Dr.

The article discusses model developmetn for HIV infected population using the System Dynamics technique. The technique has an advantage over conventional modeling technique as it is dependent more on causal relationships that involve qualitative and quantitative variables to model socioeconomic problems of a complex nature. The model has been simulated and the results haven been compared witht he available data.

Deconvolution Of Chirp Sidescan Sonar Data, Juliette W. Ioup, Maria T. Kalcic, Dale Bibee, Edit J. Kaminsky, George E. Ioup

Electrical Engineering Faculty Publications

No abstract provided.

Artificial Neural Network Learning Using Improved Genetic Algorithms, D. K. Chaturvedi

D. K. Chaturvedi Dr.

The feedforward back-propagation artificial neural networks (ANN) are widely used to control the various industrial process, for modelling, simulation of systems and forecasting. The backpropagation learning has various drawbacks such as slowness in learning, stuck in local minima, requies functional derivative of aggregation function and thresholding function to minimize error function. Various researchers have suggested a number of improvement in simple back-propagation learning algorithm developed by Widrow and Holf in 1956. In this paper, a program is developed for feedforward artificial neural network with genetic algorithm (GA) as the learning mechanism to overcome some of the disadvantages of back-propagation learning …

Induced Strain Mechanism Of Current Collapse In Algan/Gan Heterostructure Field-Effect Transistors, Grigory Simin, A. Koudymov, A. Tarakji, X. Hu, J. Yang, M. Asif Khan, M. S. Shur, R. Gaska

Faculty Publications

Gated transmission line model pattern measurements of the transient current–voltage characteristics of AlGaN/GaN heterostructurefield-effect transistors(HFETs) and metal–oxide–semiconductor HFETs were made to develop a phenomenological model for current collapse. Our measurements show that, under pulsed gate bias, the current collapse results from increased source–gate and gate–drain resistances but not from the channel resistance under the gate. We propose a model linking this increase in series resistances (and, therefore, the current collapse) to a decrease in piezoelectriccharge resulting from the gate bias-induced nonuniform strain in the AlGaN barrier layer.

Arq Protocol For Joint Source And Channel Coding And Its Applications, Bin He

Dissertations

Shannon's separation theorem states that for transmission over noisy channels, approaching channel capacity is possible with the separation of source and channel coding. Practically, the situation is different. Infinite size blocks are needed to achieve this theoretical limit. Also, time-varying channels require a different approach. This leads to many approaches for source and channel coding. This dissertation will address a joint source and channel coding that suits Automatic Repeat Request (ARQ) application and applies it to packet switching networks. Following aspects of the proposed joint source and channel coding approach will be presented:

1. The design of the proposed joint source …

Saturation Routing For Asynchronous Transfer Mode (Atm) Networks, Jose Luis Ucles

Dissertations

The main objective of this thesis is to show that saturation routing, often in the past considered inefficient, can in fact be a viable approach to use in many important applications and services over an Asynchronous Transfer Mode (ATM) network. For other applications and services, a hybrid approach (one that partially uses saturation routing) is presented. First, the minimum effects of saturation routing are demonstrated by showing that the ratio, defined as f, of routing overhead cells over information cells is small even for large networks. Second, modeling and simulation and M/D/l queuing analysis techniques are used to show that …

Predictive Performance Modeling And Simulation, Garth Crosby

FIU Electronic Theses and Dissertations

The purpose of this thesis was to create and simulate a model of an existing Campus network with a view to predict future performance. This thesis also suggests ways in which such a network can be optimized.

Such simulation and modeling can be referred to as "Predictive Performance Modeling'. In this research a model of Florida International University (University Park campus) High Speed Network was created. Simulation of the model was carried out and an ATM Backbone Analysis was done. The results obtained were compared with corresponding results obtained by network performance monitoring and measurement software tools. A strong correlation …

Feedback Correction Of Angular Error In Grating Readout, Monish Ranjan Chatterjee, Sundaram Ramachandran

Electrical and Computer Engineering Faculty Publications

Angular and wavelength READ beam errors in holographic interconnection systems are often a recurrent problem. Several strategies have been proposed to minimize or eliminate such READOUT misalignments.

Some years ago, Chatterjee and co-workers proposed a method involving READ beam wavelength tuning to correct output angular errors. In this paper, we investigate the possibility of using an acousto-optic (A-O) Bragg cell with optoelectronic feedback to dynamically correct the scattered beam for deviations in the incidence direction of the READ beam of a hologram. The concept here is based on an acoustic frequency feedback strategy used recently by Balakshy and Kazaryan for …

Low Frequency Noise In Gan Metal Semiconductor And Metal Oxide Semiconductor Field Effect Transistors, S. L. Rumyantsev, N. Pala, M. S. Shur, R. Gaska, M. E. Levinshtein, M. Asif Khan, Grigory Simin, X. Hu, J. Yang

Faculty Publications

The low frequency noise in GaNfield effect transistors has been studied as function of drain and gate biases. The noise dependence on the gate bias points out to the bulk origin of the low frequency noise. The Hooge parameter is found to be around 2×10⁻³ to 3×10⁻³.Temperature dependence of the noise reveals a weak contribution of generation–recombination noise at elevated temperatures.

Apparatus And Method For Two Stage Hybrid Space-Time Adaptive Processing In Radar And Communication Systems, Todd B. Hale, Michael C. Wicks, Raviraj S. Adve

AFIT Patents

A Two-Stage Hybrid algorithm offers significant improvement in the false alarm rate and detection performance of Space-Time Adaptive Processing in non-homogeneous environments for both radar and digital communications. The first stage analyzes data from a range cell of interest by direct data domain processing, suppressing discrete interferers within the range cell of interest. The second stage implements a purely statistical STAP algorithm, preferably an enhanced version of the Joint-Domain Localized ("JDL") statistical algorithm. For radar this second stage estimates the interference within the range cell of interest from the surrounding range cells. For a communications system, the second stage estimates …

Human Head-Neck Response To Impact Acceleration: Comparison Of Oblique To Combined Frontal And Lateral Response, Salvadore J. Guccione Jr., Edit J. Kaminsky

Electrical Engineering Faculty Publications

This paper relates human oblique head-neck kinematics to human frontal and lateral head-neck kinematics for three subjects of varying anthropometry. Head-neck kinematic response to indirect impact acceleration for an oblique test is compared to the superposition of the head/neck behavior of appropriate frontal and lateral tests for the same subject. The results have important implications in terms of the complexity required in the design and validation of omni-directional biofidelic crash test manikins and mathematical models of human head-neck response.

Turbo Space-Time Coded Modulation : Principle And Performance Analysis, Dongzhe Cui

Dissertations

A breakthrough in coding was achieved with the invention of turbo codes. Turbo codes approach Shannon capacity by displaying the properties of long random codes, yet allowing efficient decoding. Coding alone, however, cannot fully address the problem of multipath fading channel. Recent advances in information theory have revolutionized the traditional view of multipath channel as an impairment. New results show that high gains in capacity can be achieved through the use of multiple antennas at the transmitter and the receiver. To take advantage of these new results in information theory, it is necessary to devise methods that allow communication systems …

Scheduling Algorithms For High-Speed Switches, Jinhui Li

Dissertations

The virtual output queued (VOQ) switching architecture was adopted for high speed switch implementation owing to its scalability and high throughput. An ideal VOQ algorithm should provide Quality of Service (QoS) with low complexity. However, none of the existing algorithms can meet these requirements.

Several algorithms for VOQ switches are introduced in this dissertation in order to improve upon existing algorithms in terms of implementation or QoS features. Initially, the earliest due date first matching (EDDFM) algorithm, which is stable for both uniform and non-uniform traffic patterns, is proposed. EDDFM has lower probability of cell overdue than other existing maximum …

2d And 3d Surface Image Processing Algorithms And Their Applications, Jianlin Gao

Dissertations

This doctoral dissertation work aims to develop algorithms for 2D image segmentation application of solar filament disappearance detection, 3D mesh simplification, and 3D image warping in pre-surgery simulation. Filament area detection in solar images is an image segmentation problem. A thresholding and region growing combined method is proposed and applied in this application. Based on the filament area detection results, filament disappearances are reported in real time. The solar images in 1999 are processed with this proposed system and three statistical results of filaments are presented.

3D images can be obtained by passive and active range sensing. An image registration …

Channel Estimation And Signal Enhancement For Ds-Cdma Systems, Kun Wang

Dissertations

This dissertation focuses on topics of Bayesian-based multiuser detection, space-time (S-T) transceiver design, and S-T channel parameter estimation for direct-sequence code-division multiple-access (DS-CDMA) systems.

Using the Bayesian framework, various linear and simplified nonlinear multiuser detectors are proposed, and their performances are analyzed. The simplified non-linear Bayesian solutions can bridge the performance gap between sub-optimal linear multiuser detectors and the optimum multiuser detector.

To further improve the system capacity and performance, S-T transceiver design approaches with complexity constraint are investigated. Novel S-T receivers of low-complexity that jointly use the temporal code-signature and the spatial signature are proposed. Our solutions, which lead …

Modeling, Design And Scheduling Of Computer Integrated Manufacturing And Demanufacturing Systems, Ying Tang

Dissertations

This doctoral dissertation work aims to provide a discrete-event system-based methodology for design, implementation, and operation of flexible and agile manufacturing and demanufacturing systems. After a review of the current academic and industrial activities in these fields, a Virtual Production Lines (VPLs) design methodology is proposed to facilitate a Manufacturing Execution System integrated with a shop floor system. A case study on a back-end semiconductor line is performed to demonstrate that the proposed methodology is effective to increase system throughput and decrease tardiness. An adaptive algorithm is proposed to deal with the machine failure and maintenance. To minimize the environmental …

Joint Source Channel Coding For Progressive Image Transmission, Minyi Zhao

Dissertations

Recent wavelet-based image compression algorithms achieve best ever performances with fully embedded bit streams. However, those embedded bit streams are very sensitive to channel noise and protections from channel coding are necessary. Typical error correcting capability of channel codes varies according to different channel conditions. Thus, separate design leads to performance degradation relative to what could be achieved through joint design. In joint source-channel coding schemes, the choice of source coding parameters may vary over time and channel conditions. In this research, we proposed a general approach for the evaluation of such joint source-channel coding scheme. Instead of using the …

Novel Multiuser Detection And Multi-Rate Schemes For Multi-Carrier Cdma, Pingping Zong

Dissertations

A large variety of services is [sic] expected for wireless systems, in particular, high data rate services, such as wireless Internet access. Users with different data rates and quality of service (QoS) requirements must be accommodated. A suitable multiple access scheme is key to enabling wireless systems to support both the high data rate and the integrated multiple data rate transmissions with satisfactory performance and flexibility. A multi-carrier code division multiple access (MC-CDMA) scheme is a promising candidate for emerging broadband wireless systems. MC-CDMA is a hybrid of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). The …

Plasma Induced Damage To Si And Sige Devices And Materials, Wei Zhong

Dissertations

This thesis studied the plasma-induced damage to Si and strained Si_1-xGe_x, and the resulting change in device characteristics. The energetic particles (ions, electrons and photons) in plasma reactor present a potentially hostile environment for processing VLSI devices. An inductively coupled plasma (ICP) reactor was used to study its damage effects to thin gate oxides. Electrical characterizations by C-V, ramped voltage breakdown (RVB) and deep-level transient spectroscopy (DLTS) measurement, and x-ray photoelectron spectroscopy (XPS) analysis were employed to investigate the damages to thin gate oxides and Si/SiO₂ interface. The shift of flat band voltage, the reduction …

Performance Analysis And Resource Allocation In Cdma Wireless Networks For Multimedia Services, Sebnem Zorlu

Dissertations

The proliferation of Internet and demand for wireless services necessitate large increases in capacity and data rates in order to support different multimedia services. Wireless systems will be required to support sources with a variety of traffic characteristics and quality of service requirements. This requires algorithms for admission control and resource allocation at the session, burst and packet levels. The purpose of this research is to develop and analyze optimal resource allocation strategies to maximize throughput of wireless systems with integrated services. Given the multimedia user requirements, the problem addressed can be formulated as a constrained optimization problem. The objective …

Buffer Management And Cell Switching Management In Wireless Packet Communications, Jongho Bang

Dissertations

The buffer management and the cell switching (e.g., packet handoff) management using buffer management scheme are studied in Wireless Packet Communications.

First, a throughput improvement method for multi-class services is proposed in Wireless Packet System. Efficient traffic management schemes should be developed to provide seamless access to the wireless network. Specially, it is proposed to regulate the buffer by the "Selective- Delay Push-In (SDPI)" scheme, which is applicable to scheduling delay-tolerant non-real time traffic and delay-sensitive real time traffic. Simulation results show that the performance observed by real time traffics are improved as compared to existing buffer priority scheme in …

Design Of Traffic Shaper / Scheduler For Packet Switches And Diffserv Networks : Algorithms And Architectures, Surong Zeng

Dissertations

The convergence of communications, information, commerce and computing are creating a significant demand and opportunity for multimedia and multi-class communication services. In such environments, controlling the network behavior and guaranteeing the user's quality of service is required. A flexible hierarchical sorting architecture which can function either as a traffic shaper or a scheduler according to the requirement of the traffic load is presented to meet the requirement. The core structure can be implemented as a hierarchical traffic shaper which can support a large number of connections with a wide variety of rates and burstiness without the loss of the granularity …

Optical Properties Of Photonic Crystals, Anand G. Shenoy

Theses

The ability to confine light in three dimensions has important implications for quantum optics and quantum-optical devices. Photonic crystals, the optical analog of electronic crystals, provide us a means of achieving this goal. This analogy has motivated a whole new series of experimental and theoretical searches for elusive photonic band-gap structures. Combinations of metallic and dielectric materials can be used to obtain the required three-dimensional (3D) periodic variation in the dielectric constant. This could pave the way for photonic crystal structures that have widespread applications.

The working of 3D photonic crystals into the wavelength regimes where most optoelectronic devices operate, …

Propagation And Scattering Of Collimated Beam Wave In Vegetation Using Scalar Transport Theory, Michael Yu-Chi Wu

Theses

The scalar time-dependent equation of radiative transfer is used to develop a theory of pulse beamwave propagation and scattering in a medium character ized by many random discrete scatterers which scatter energy strongly in the forward scattering direction. Applications include the scattering of highly collimated millimeter waves in vegetation and optical beams in the atmosphere. The specific problem analyzed is that of a periodic sequence of Gaussian shaped pulses normally incident from free space onto the planar boundary surface of a random medium half-space, such as a forest, that possesses a power scatter (phase) function consisting of a strong, narrow …

Overview Of Acousto-Optic Bistability, Chaos, And Logical Applications, Monish Ranjan Chatterjee, Erol Sonmez

Electrical and Computer Engineering Faculty Publications

An overview is presented of the key results in the field of acousto-optic bistability in the past two decades. It is shown that the basic acousto-optic bistable device may be described as a nonlinear dynamical system which satisfies a quadratic map. Thereafter, details are presented of several analytical methods, computer modeling approaches, including the SPICE circuit modeling technique, and experiments that have been used to understand the phenomenon.

Extensions to logical and digital applications are also discussed.

Fuzzified Neural Network Approach For Load Forecasting Problems, D. K. Chaturvedi, P. S. Satsangi, P. K. Kalra

D. K. Chaturvedi Dr.

In load forecasting, the operator or the concerned person uses his or her experience and intuitions to obtain a good guess of the load demand. This guess is normally supported by sophisticated mathematical prediction techniques. The short term load not only varies from hour to hour, but is also influenced by the nature of events, load demand, the type of the load considered, seasonal variations, weekend day or holidays, and also by sudden demand and loss of load. Accordingly, it is quite clear that the electrical load-forecasting problem is quite difficult to model with mathematical difference or differential equations. In …

Broadband Application Of High Impedance Ground Planes, Keven J. Golla

Theses and Dissertations

Electrical conductors have long been the only materials available to antenna designers for reflecting structures. However, recently reported high impedance ground plane (HIGP) structures offer an alternative by creating image currents and reflections, within a limited frequency stop-band, that are in-phase with a source rather than out-of-phase as for a perfect electric conducting (PEC) surface. Also, the high impedance structures suppress surface waves while surface waves propagate on PEC surfaces. This research explores broadband antenna applications for HIGP structures. A broadband surface mount antenna is applied to both a homogeneous narrowband HIGP and a spatially varying broadband HIGP design. Measurements …

Wavelet-Based Audio Embedding & Audio/Video Compression, Michael J. Mendenhall

Theses and Dissertations

With the decline in military spending, the United States relies heavily on state side support. Communications has never been more important. High-quality audio and video capabilities are a must. Watermarking, traditionally used for copyright protection, is used in a new and exciting way. An efficient wavelet-based watermarking technique embeds audio information into a video signal. Several highly effective compression techniques are applied to compress the resulting audio/video signal in an embedded fashion. This wavelet-based compression algorithm incorporates bit plane coding, first difference coding, and Huffman coding. To demonstrate the potential of this audio embedding audio/video compression system, an audio signal …

Tilted Bilayer Membranes As Simple Transmission Quarter-Wave Retardation Plates, R. M.A. Azzam, Fadi A. Mahmoud

Electrical Engineering Faculty Publications

A tilted bilayer membrane, which consists of two thin films of transparent optically isotropic materials of different refractive indices, can function as a transmission quarter-wave retarder (QWR) at a high angle of incidence. A specific design using a cryolite-Si membrane in the infrared is presented, and its tolerances to small shifts of wavelength, incidence angle, and film thickness errors are discussed. Some designs provide a dual QWR in transmission and reflection. Such devices provide simple linear-to-circular (and circular-to-linear) polarization transformers. Bilayer eighth-wave retarders without diattenuation are also introduced.

Video Indexing And Summarization Using Motion Activity, Kadir Askin Peker

Dissertations

In this dissertation, video-indexing techniques using low-level motion activity characteristics and their application to video summarization are presented. The MPEG-7 motion activity feature is defined as the subjective level of activity or motion in a video segment. First, a novel psychophysical and analytical framework for automatic measurement of motion activity in compliance with its subjective perception is developed. A psychophysically sound subjective ground truth for motion activity and a test-set of video clips is constructed for this purpose. A number of low-level, compressed domain motion vector based, known and novel descriptors are then described. It is shown that these descriptors …