Digital Commons Network^™

Output Feedback Applied To Observer Based Controller, Nainn-Ping Ke

Theses

This thesis presented the results of an investigation on the stability robustness issues of the Infinite-horizon linear-quadratic-Gaussian (IH-LQG) control system design methodology. The goal of this research deals with the design of Observer based controller using Output Feedback (00F), and this is a new method to solve estimation problems. The primary difference of this method from others is that the estimator is considered as a system. The results of this research shows that the optimal output feedback control law and the optimal state estimator can be designed by the optimal output feedback control method, and shows that the OOF Weighting …

Visual System Modeling And System Response Analysis, Zhongquan Li

Theses

Based on the anatomical structure, a structural model of the visual system was established. System responses of different stimulations were analyzed based on the model. More extensive study was made on the system impulse response. A mathematical model with parameters representing prominent process components was developed to represent the system response in a compact form and the parameters were statistically studied to correlate to the real physiological characteristics of the visual system. The parameters of the model were used to fit the system intensity response function. The result shows that it is a more quantitative way to construct the system …

Study Of System Dynamics In A Primitive Identification/Counter Model, Zofia Monczka

Theses

Previous study of a simplified identification/counter model (1), (2) indicated bifurcations in its behavior. In order to study this topic, graphical representations of the system dynamics are derived. Analysis of the structure of the identification/counter model reveals the reasons why the graphs assume their given shapes.

The graphical representations of the system are used to characterize the system behavior and thus explain the bifurcations previously encountered. These representations are then used as the basis for deriving a general model for system behavior. Analysis of this model for a specific range of parameter values indicates that the system contains numerous additional …

Network Realizability Approach To Robust Stability Of Discrete-Time Systems Characterized By Polynomials, Sri Indran Rasiah

Theses

In system design, the coefficients of a characterizing polynomial are usually not precisely known but can be bounded from above and below by real numbers. The requirement of robust system design from the stability standpoint demands, then, the guaranteeing of the stability of a set of polynomials.

Stability theorems for continuous-time systems and discrete-time systems, are studied in this report. It is shown that one more condition has to be included into each of the theorem. The revised theorem for continuous-time systems is proved through network realizability theory. The one for discrete-time systems is, then, proved via the use of …

Design Of Governor-Turbine Models In Stability Studies, Vidyanand Swaminathan

Theses

This thesis investigates the effect of hydro governor-turbine models on the steady state stability of an automatically controlled electric power system. Basically two kinds of hydro governor-turbine models, namely, Impulse and Francis type are studied in depth. Design of a compensating network has also been proposed, which can help improve the stability conditions of a power system which employs a poor governor-turbine model.

The power system investigated includes a large sized hydro generating unit connected to an infinite bus via a power network. This generator employs a modern three-channel fast-acting automatic voltage regulator (AVR). For any operating condition, stability results …

Analysis On Dielectric Resonators, Xuan Tu

Theses

This dissertation deals with the studies and analysis of Dielectric Resonators (DR). A shielded dielectric iesonator structure, consisting of the substrate, the spacer, the dielectric resonator and the metallic shielding is modelled theoretically. The theoretical expressions for the resonance fields are derived by using radial-mode matching and axial mode-matching techniques. In these techniques, the structure is divided into partial regions and the fields in each pai tial region are represented in terms of a series of the appropriate modes with unknown coefficients. Matching the adjacent regions yields a system of linear or nonlinear equations — which then are solved. The …

Nonlinear Variants Of The Least Mean Square (Lms) Algorithm, John George Van Saders

Theses

Adaptive systems using the LMS algorithm or its variants usually require bilinear correlation multipliers with high dynamic range and large bandwidth. The class of LMS-type algorithms utilizing zero-memory limiters (on one or both correlation multiplier inputs) to reduce dynamic range are examined. The correlator limiters may be included to simplify the hardware implementation or may arise due to limited dynamic range of the loop components. The application of a theorem due to Price provides a technique for simplifying the analysis, which otherwise might be extremely difficult. The analysis provides closed-form expressions for the mean weight convergence behavior, permitting examination of …

Rays And Beams Near The Shadow Boundary, Weixing Gao

Theses

Asymptotic techniques in wave propagation problems exhibit attractive features in computational aspects compared to numerical methods. However, they experience problems in complicated environments due to the transition regions associated with them. The transition region involving a shadow boundary in the downward refractive index profile has been investigated. The ray paths were determined solving the ray equation analytically. The Green's function due to a line source is constructed and evaluated using numerical integration (reference solution) and asymptotic techniques. Then, the field produced by the source, is synthesized, using superposition of beams generated from complex source point representation. The floating parameters such …

Reduced Complexity Receivers For Trellis Coded Modulations Via Punctured Trellis Codes, Bonchul Koo

Theses

We introduce a new concept, called matched punctured trellis encoding, that simplifies the complexity of Maximum Likelihood Sequence Estimation (MLSE) receivers for combined trellis encoding and modulations with memory. Matched punctured trellis encoding is applied to tamed frequency modulation (TFM) which is a bandwidth efficient correlative - FM scheme. TFM finds applications in satellite, microwave radio, and mobile communications.

Our approach is based on puncturing a rate - 1/2 matched convolutional code to obtain a rate - 2/3 mismatched code. A matched code is one that produces trellis coded modulations of minimum complexity. Puncturing these codes to obtain mismatched codes …

Modelling And Parameter Estimation In Clinical Electrooculography, Shengche Hsu

Theses

The Corneoretinal potential (CRP) was discovered in 1848. Its response to changes in light intensity can provide information relevant in the diagnosis of some retinal degenerative disorders. The indirectly measured CRP is referred to as electro-oculography (EOG). A system for automatic data acquisition and modelling, providing graphic presentation, data processing and file management, has been developed. A linear feedback model is proposed to represent the dynamics of the EOG signal. Model parameters are estimated by the nonlinear least-square method. The effect of measurement time on the reliability of parameter estimation is discussed.

Trellis Coded Partial-Response Channels, Kumari Yalamanchili

Theses

Binary partial-response channels with transfer functions (1+D), (1-D) and (1 — D²) are intersymbol-interference channels which find applications in baseband data communications and magnetic recording systems (tapes, discs, compact discs, etc.). In this thesis we develop a coding technique for improving the reliability of digital transmission over noisy partial-response channels with the above transfer functions. We do so by introducing a new concept, called matched encoding, which arises in the context of trellis coding for channels with memory.

We use inner and outer trellis coding of the partial-response channels. The inner codes called matched inner coset codes, are …

Methods Of Achieving High Speed On Data Flow Machines, Chung-Lin Yu

Theses

Simultaneity is a key to high speed and large computation. Assuming hardware components of a given speed, it is the only remaining consideration in achieving raw speed. Simultaneity can be shackled by dependencies, however, and years of hardware and software work have been devoted to understanding the types of dependencies and how they can be obeyed or removed from a computation.

In this thesis, the principles of the data flow machines and the structure of the data flow languages are illustrated. Various methods of achieving high speed are discussed. These methods include streams, Lenient Cons (I-structure), and dependence-driven computation, which …

One-Dimensional Parametric Inverse Scattering For Lossless Dispersive Media, Frank Gangi

Theses

In this thesis, the effects of high frequency noise on a perturbational inversion algorithm for a stratified dispersive medium are investigated. It is shown that the perturbational algorithm becomes unstable under high frequency noise. The physical origin of this instability is discussed.

In order to enhance the robustness of the perturbational inverse scattering solution, a parametric inversion algorithm is implemented. The improvement by the use of a parametric inversion is given quantitatively by the profile-to-error ratio (PER). Examples of the two-pole and the three-pole reflection coefficients are compared and contrasted.

Study Of Ionized Cluster Beam Techniques For Reactive Deposition Of Gallium Nitride Thin Films, Jyh Sheen

Theses

This thesis is divided into two parts. The first part investigates the Ionized Cluster Beam( ICB ) technique through measurements of the energy of ionized gallium beam. The presence of ions and their kinetic energy in the ICB technique is advantageous in the formation process of thin film. The results of retarding potential measurement are comparable with the presence of clusters as large as 500 atoms. The second part examines the formation of gallium nitride thin film. In order to enhance the reaction of gallium and nitrogen, dissociation of molecular nitrogen by microwave discharge method was used to generate atomic …

Firmware Toolkit For Larynx Synchronous D.S.P., Shih-Chieh Su

Theses

During the past ten years, digital signal processing has been an extremely active and dynamic field. Advances in integrated circuit technology and in processor architecture have greatly enlarged the scope of the technical areas to which digital signal processing techniques can be applied. Research in fundamental signal processing techniques and algorithms has led to dramatic improvements in the efficiency of signal processing systems.

This thesis creates a fast and cheap DSP package for 8052AH-BASIC. This is a useful and potential package when we apply research in speech science and medical diagnostics. It exploits the latest software-in-silicon technology to create a …

Spectrum Analysis Of Heart Rate Variability, Xuming Wang

Theses

This research investigated the respiratory influence on heart rate variability. The heart rate spectrum was obtained from the heart rate variability signal which was extracted from the electrocardiogram We then studied the magnitude of the respiration peak in the heart rate spectrum and examined the dependence of the magnitude of this peak on breathing frequency, subject and day.

An experiment designed to simultaneously acquire the electrocardiogram and the respiration signal was conducted on ten people ranging from 22 to 55 years of age (3 females, 7 males). Three tests were performed on each subject. In each test, 2 different postures …

The Application Of The Ordered List Method And The Dynamic Programming To The Unit Commitment, Hoang Uong

Dissertations and Theses

The thesis presents a method of committing generating units in a hydro-thermal power system within practical computer resources such as computer time and data storage.

Microprocessor Based Protection Of Induction Motors Using Thermal, Mechanical, And Skin Effect Electrical Models To Predict Motor Temperature Rise, Nader S. Moharari

Masters Theses and Doctoral Dissertations

This study investigates induction motor performance during a variety of system and load conditions. A computer simulation is used to characterize the motor behavior during normal operation, lockedrotor case, high inertia loading, and overloading conditions. Motor temperature at critical points is estimated. A microprocessor protection scheme based on motor temperature is proposed. Previous studies assume a linear relationship between motor impedance and frequency when calculating motor temperature. In this study an electrical model, based on Maxwell's equations, is used in conjunction with a mechanical model, to represent the motor during dynamic state conditions. The model accounts for the rotor bar …

Convergence Properties Of The Waveform Relaxation Method As Applied To Electric Power Systems, Marija D. Ilić, J. K. White, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Several theoretical results are presented and simple examples examined in order to determine the suitability of waveform relaxation for transient power system simulation. This examination leads to two practical suggestions that can easily be satisfied for power systems. The first is to break the simulation interval into sections, the first of which should be narrow and be used to kill off errors in the initial guess that activate the stiff modes. The second is to partition the system into subsystems that are stable, as this not only aids convergence but ensures multirate numerical stability.

Efficient Multi-Layer Channel Routing, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

No abstract provided.

Performance Modeling And Enhancement For The Atamm Data Flow Architecture, Sukhamoy Som

Electrical & Computer Engineering Theses & Dissertations

Algorithm To Architecture Mapping Model (ATAMM) is a new marked graph model from which the rules for data and control flow in a homogeneous, multicomputer, data flow architecture may be defined. This research is concerned with performance modeling and performance enhancement for periodic execution of large-grain, decision-free algorithms in such an ATAMM defined architecture. Performance measures and bounds are established. Algorithm transformation techniques are identified for performance enhancement and reduction of computing element requirements. Operating strategies are developed for optimum time performance and for sub-optimum time performance under limited availability of computing elements. An ATAMM simulator is used to test …

Use Of The Lms Algorithm In Ecg Analysis, Xiaohua Yang

Theses

The purpose of this thesis is to develop an IBM PC-AT based system to effectively process electrocardiogram (ECG) signals. Adaptive filter theory is used to implement a noise cancellation system (adaptive noise canceller), which adaptively cancels the ECG signals resulting in real ECG noise. The adaptive process is based on the well known least-mean square (LMS) algorithm.

The noise canceling system is software based. Several programs have been written, which include analog to digital converter control, data acquisition and storage, data retrieval, adaptive filtering and digitized data graphics.

The thesis presents numerous computer experiments. The performance of the adaptive noise …

Progressive Transmission Of Images Using Pyramidal Structure, Chin-Hua Hsu

Theses

A progressive image transmission scheme based upon Laplacian pyramid structure is used for image coding over low-bandwidth channels. The filtering and differential pulse code modulation (DPCM) methods of image coding are generalized to allow quantization of the Laplacian images. Filtering is performed with a local, symmetric weighting function. The three different quantizers, (1) scalar quantizer, (2) memoryless vector quantizer (VQ), and (3) finite state vector quantizer (FSVQ), are used here to compare the results. In the receiver end, the image can be reconstructed using reverse procedure. The reconstructed image is not the same as the original image because of the …

Theoretical Model For The Images Formed By A Spherical Particle In A Coherent Imaging System: Comparison, Scott Alan Schaub, D. R. Alexander, J. P. Barton

Department of Electrical and Computer Engineering: Faculty Publications

A simple theoretical model is presented that allows calculation of the image produced by a spherical absorbing particle illuminated by monochromatic, coherent laser light. Results presented in this paper are restricted to a singe-lens imaging system, although generalization to more complex imaging system configurations would be straightfoward. The method uses classic Lorenz-Mie scattering theory to obtain the electromagnetic field external to an absorbing spherical particle and a Fourier optics approach to calculate the intensities in the image plane. Experimental results evaluating focus characteristics are examined for 50 um diameter water droplets using an N2 laser imaging system in conjunction with …

Assessment Of Squirrel-Caused Power Outages, J. Chris Hamilton, Ron J. Johnson, Ronald M. Case, Michael W. Riley

School of Natural Resources: Faculty Publications

Squirrel-caused power outages in Lincoln and Omaha, Nebraska, were evaluated by examining company power outage reports and by consulting with power company representatives. Reports showed that squirrel-caused outages at pole-mounted transformers were most prevalent during May, June, and October (48% of total) and between 1 and 4 h after sunrise (38%), patterns that coincide with squirrel dispersal or morning activity periods. In Lincoln, 1980 and 1981, squirrels caused 177 outages per year, which was 24% of all outages and 90% of animal-caused outages. Estimated minimum annual costs were $23 364 for repairs, public relations, and lost revenue while meters were …

Feasibility Study Of Maine's Small Hydropower Potential, James D. Sysko

Maine Collection

Feasibility Study of Maine's Small Hydropower Potential

Prepared by James D. Sysko, Small Hydro East, for the Maine State Planning Office, Maine Office of Energy Resources, January 1989.

"This study focuses on finding potential hydropower sites of approximately 50 kw to 1000 kw in capacity."

Nanosecond Optical Quenching Of Photoconductivity In A Bulk Gaas Switch, M. S. Mazzola, K. H. Schoenbach, V. K. Lakdawala, S. T. Ko

Electrical & Computer Engineering Faculty Publications

Persistent photoconductivity in copper-compensated, silicon-doped semi-insulating gallium arsenide with a time constant as large as 30 µs has been excited by sub-band-gap laser radiation of photon energy greater than 1 eV. This photoconductivity has been quenched on a nanosecond time scale by laser radiation of photon energy less than 1 eV. The proven ability to turn the switch conductance on and off on command, and to scale the switch to high power could make this semiconductor material the basis of an optically controlled pulsed-power closing and opening switch.

Gaas Photoconductive Closing Switches With High Dark Resistance And Microsecond Conductivity Decay, M. S. Mazzola, K. H. Schoenbach, V. K. Lakdawala, R. Germer, G. M. Loubriel, F. J. Zutavern

Electrical & Computer Engineering Faculty Publications

Silicon-doped n-type gallium arsenide crystals, compensated with diffused copper, were studied with respect to their application as photoconductive, high-power closing switches. The attractive features of GaAs:Cu switches are their high dark resistivity, their efficient activation with Nd:YAG laser radiation, and their microsecond conductivity decay time constant. In the authors' experiment, electric fields are high as 19 kV/cm were switched, and current densities of up to 10 kA/cm² were conducted through a closely compensated crystal. At field strengths greater than approximately 10 kV/cm, a voltage `lock-on' effect was observed.

Randomized Routing On Fat-Trees, Ronald I. Greenberg, Charles E. Leiserson

Computer Science: Faculty Publications and Other Works

Fat-trees are a class of routing networks for hardware-efficient parallel computation. This paper presents a randomized algorithm for routing messages on a fat-tree. The quality of the algorithm is measured in terms of the load factor of a set of messages to be routed, which is a lower bound on the time required to deliver the messages. We show that if a set of messages has load factor lambda on a fat-tree with n processors, the number of delivery cycles (routing attempts) that the algorithm requires is O(lambda + lg n lg lg n) with probability 1-O(1/n). The best previous …

Lower Bounds On The Area Of Finite-State Machines, M. J. Foster, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

There are certain straightforward algorithms for laying out finite-state machines. This paper shows that these algorithm are optimal in the worst case for machines with fixed alphabets. That is, for any s and k, there is a deterministic finite-state machine with s states and k symbols such that any layout algorithm requires Ω(ks log s) area to lay out its realization. Similarly, any layout algorithm requires Ω(ks^2) area in the worst case for nondeterministic finite-state machines with s states and k symbols.