A prony algorithm for shallow water waveguide analysis

Submitted in partial fulfillment of the requirements for the degree of Ocean Engineer at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 1987Low frequency acoustic propagation in shallow water is examined from a normal mode context. By modelling the far field pressure field as a modal sum, propagating mode characteristics of wavenumber, initial phase, attennation and amplitude may be estimated using a high resolution parameter modeling technique. The advantages of such an algorithm are the resolution of closely spaced modes in a range independent environment and the ability to analyze range dependent waveguides. This thesis presents the application of a Prony algorithm to the shallow water environment. The algorithm operates directly on the signal matrix. Synthetically generated, range independent pressure fields are used to analyze the technique'S performance and to observe its sensitivity to variations in model specifications. Noise is added to determine the threshold of acceptable performance. As a consequence of field data tests, further enhancements to the algorithm are suggested. Range dependent performance is evaluated on a coastal wedge example and geoacoustic parameter shift example

Functional Techniques for Data Analysis

This dissertation develops a new general method of solving Prony's problem. Two special cases of this new method have been developed previously. They are the Matrix Pencil and the Osculatory Interpolation. The dissertation shows that they are instances of a more general solution type which allows a wide ranging class of linear functional to be used in the solution of the problem. This class provides a continuum of functionals which provide new methods that can be used to solve Prony's problem

Composite beams with viscoelastic interaction. An application to laminated glass.

A practical way to calculate the response of laminated glass is to consider both glass and polymeric interlayer as linear elastic materials; the viscoelastic behavior of the polymer is evaluated assuming equivalent elastic moduli, that is, the relaxed moduli under constant strain after a time equal to the duration of the design action. Here, we analytically solve the time-dependent problem of simply-supported laminated-glass beams, modeling the response of the polymer by a Prony’s series of Maxwell elements. The obtained results, in agreement with a full 3-D viscoelastic finite-element numerical analysis, emphasize that there is a noteworthy difference between the state of strain and stress calculated in the full-viscoelastic case or in the aforementioned “equivalent” elastic problem. The second approach gives in general results that are on the side of safeness, but the design may be too conservative for short-time actions, whose duration depends upon the polymer type

Procjena parametara sinkronog generatora iz podataka mjerenja pokusa udarnog kratkog spoja uzimajući u obzir variranje brzine rotora

Procedure to estimate parameters of synchronous hydro-generator (18 MVA) from sudden short-circuit measurement data is presented. Test performed was under small and slow speed variation and reduced excitation current. Data were collected in the form of sampled time series of measured armature voltage and currents prior to and during the sudden short-circuit test. Neither the rotor speed nor the angle between rotor and stator were measured. Detailed method of initial and final estimation of parameters were also appraised (Prony\u27s method and constrained minimization technique) considering behaviour of the rotor angle and speed during the test.Prezentiran je postupak procjene parametara sinkronog hidrogeneratora (18 MVA) iz podataka mjerenja udarnog tropolnog kratkog spoja. Pokus je načinjen u uvjetima polagane i male promjene brzine vrtnje i snižene struje uzbude. Podaci su prikupljeni u obliku uzorkovanih vremenskih nizova mjerenih napona i struja armature prije i tijekom udarnog kratkog spoja. Tijekom pokusa nisu posebno mjereni niti brzina, a niti kut izmedu rotora i statora. Također su razmotrene pojedinosti primijenjenih metoda početne i konačne procjene parametara (Pronyjeva metoda, postupak minimizacije s ograničenjima) uključujući i procjenu ponašanja kuta i brzine vrtnje tijekom pokusa

Advanced ROCOF protection of distribution systems

When islanding occurs, power supply from the main grid is interrupted which causes a problem when distributed generators continue to provide power into distributed networks. An islanding situation should be detected accurately soon after the island is formed. Because failure to trip the islanded distributed resource can lead to a number of problems for the resource and the connected load. Although ROCOF islanding detection method is the most commonly employed anti-islanding protection technique, it provides fast detection and easily implementation. It is sensitive to the system disturbance. Therefore, the application of the ROCOF relay to detect system islanding has been limited. This thesis proposes a solution to enhance the performance of the ROCOF relay by cooperation with rate of change of power or v2/p interlock function. During system load variation, the false operation of ROCOF relay can be blocked effectively. It is validated by applied in grid-connected synchronous generator, Doubly-fed Induction generator (both simulation and experiment) and microgrid. The principle of rate of change of power or v2/p interlock function are presented in this thesis. The new interlock function v2/p with ROCOF relays works well for different types of DGs within a short detection time without introducing perturbation into the system, which are the advantages over other active and hybrid islanding detection methods. The performances characteristics of ROCOF relays for DGs islanding detection (i.e. frequency measuring methods, measuring windows, generator inertia constant, relay settings and load power factor) are investigated. In addition, two other islanding detection methods (impedance measurement (active method) and the Total Harmonic Method) are applied to the grid-connected DFIG distributed system, the comparison and effectiveness of these two methods utilized in islanding and load changing conditions are also discussed

Joint Source-Channel Coding with Real Number BCH and Reed-Solomon Codes: Their Properties and Performance in the Presence of Additive Noise

This thesis investigates the joint source-channel coding properties of real number BCH and Reed-Solomon codes in the presence of additive noise. From previous results, it was known that additive noise can cause the error correction ability of a real number code to degrade. This degradation results in decoding failures. Knowing this, there are two main objectives of this research. The first objective is to determine under what conditions a given real number code is reliable. More specifically, for a given real number BCH or Reed-Solomon code, I sought to determine the highest additive noise level for which the real number code could still be accurately decoded within a specified probability of failure. Using these results, the second objective is to determine whether a real number code can obtain better joint source-channel performance than a comparable finite field code. During the investigation process, I formalized the source coding properties that had been mentioned in previous research. The frrst objective was met by deriving an upper bound to the probability of a decoding failure as a function of the signal to noise ratio, the transmission error magnitudes and the code parameters. These bounds assume that a full search decoding method is implemented. Siflce the full search method is impractical and the traditional decoding method performed poorly in the presence of additive noise, an alternate decoding algorithm was developed. This algorithm attempts to combine the directness of the traditional BCH decoding algorithm with the robustness of the full search decoder. The second objective was met with mixed success since deriving an accurate average channel coding performance for multiple error correcting codes proved elusive. However, simulated results for a four error correcting code is examined.Electrical Engineerin