The object of this paper is to derive Landau's theory of quantized hydrodynamics from the many-particle Schroedinger equation. Landau's results are obtained, together with an additional term in the Hamiltonian.

In the world of networked system, average consensus is an important dimension of co-ordinate control and cooperation. Since the communication medium is digital, real value cannot be transmitted and we need to perform quantization before data transmission. But for the quantization, error is introduced in exact value and initial average is lost. Based on this limitation, my 16 bit quantization method (sending MSB in 1-4 cycle and MSB+LSB in 5th cycle) reduces error significantly and preserves initial average. Besides, it works on all types of graphs (star, complete, ring, random geometric graph). My other algorithm, distributing averaging algorithm (PQDA) with probabilistic quantization also works on random geometric graph, star, ring and slow co-herency graph. It shows significant reduced error and attain strict consensus.

This thesis will examine the interactions of a cloud of charged vortex rings (CVRs) in the low temperature limit in helium-II (0.2 < T < 0.8 K) in a cubic cell containing a quasi-uniform electric field. A model of geometric collisions between vortex rings is proposed to explain the observed critical density of CVRs given by nR^3 ~ 3 cm^{-1} R where n is the CVR number density and R is the average CVR radius. This model was simulated in a simplified situation where two perfectly circular parent CVRs collide geometrically to create two perfectly circular daughter CVRs, conserving momentum and charge and dissipating a random amount of energy. The simulations are in qualitative and quantitative agreement with experiment.For an intense injection of CVRs into a strong electric field the CVRs quickly reconnect with one another to form a tangle of charged vortex loops. These loops move as one quasi-connected unit, it was found that the charged tangle's response to forcing was given by a law of the form t3 ~ (QE)^{-1/3} where t3 is the charged tangle time of flight, Q is the charge of the tangle and E is the applied electric field. Simulations of the displacement current induced in two electrodes in the cell were run in order to glean some information as to the transverse distribution of charge in the tangle, which was found to be approximately constant with time of flight and injected charge.

No description available.

This thesis focuses on the design and implementation of a three-level Class D audio amplifier by applying recently developed sliding-mode quantized control. The designed controller, which consists of the analog filters and logic circuit, switches an H-bridge Class-D amplifier with a lowpass LC filter and operates it in the sliding mode, in order to achieve desired stability and high fidelity in the audio band. The experimental result shows that the lowest THD+N (total harmonic distortion plus noise) can be as low as 0.02% at 1 kHz. The performance is better than most of the available commercial products.

A quantized control means that the control force is restricted to takes only a finite number of prescribed levels. The well-known bang-bang control or relay control belongs to this category. This kind of control has the advantage of simple circuit realization using electronic switches or relays that feature low power consumption in their on-off operation. However, quantized control introduces noise and distortion, and even worse its high nonlinearity makes the stabilizing compensator design difficult. This thesis applies the concept of dynamic sliding mode to the synthesis of a multi-level quantized control, with the aim to stabilize the system, perform reference tracking and attenuate the switching noise. The applicability of the presented sliding-mode quantized control is demonstrated on a three-level buck converter. Compared with the conventional PWM (Pulse-Width Modulation) scheme, it eliminates the use of a complex three-level PWM generator and a current sensor. A 12V/8V three-level buck converter with sliding mode quantized control is designed and realized, which shows the output voltage with 0.4625% of average DC error, 2.8988% of the static output ripple and 2.3% of load regulation error in response to the load current steps from 0A/3A to 3A/0A, at a slew rate of 6.25A/£gsec.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / In this paper, a novel zigzag scanning concept of quantized coefficients for H.264/AVC is introduced. In order to scan the quantized coefficients efficiently, the statistical occurrence values of the quantized coefficients after the final mode decision are utilized. We develop a zigzag scanning pattern by reordering the statistical occurrence values in descending order. In addition, we consider the temporal and spatial correlation among the frames to classify the zigzag scanning pattern. In particular, we focus on the macroblock level zigzag scanning so that the proposed method will have the different zigzag scanning pattern based on the macroblock. Experimental results show that the proposed scheme reduces the total bits up to 4.05% and 3.67% while introducing either negligible loss of video quality for intra- and inter mode, respectively.

<p> A new radar tracking detector using fixed delay lines in place of continuously variable delay lines is described. The fixed delays are switched in and out depending on the output of a correlator. Results of a working system are shown using bang-bang feedback and analog-to-digital feedback, for tracking a time-varying delay. </p> / Thesis / Master of Engineering (MEngr)

Radio spectrum has become a scarce and priced resource due to the rapid growth of wireless networks. However, recent surveys conducted by the FCC indicate that a large part of the allotted frequency spectrum lies unused. Cognitive radio systems, built on the software defined radios, allow the efficient usage of these unused frequency spectrum. Cognitive radio systems can be modeled as a multiple access channel in which certain users have the priority (primary users) while others (cognitive or secondary users) are allowed to access the channels without causing any interference to the primary users. However a secondary user’s transmissions not only encounter high levels of uncertainty and variability in the number of channels available to them, but they also suffer data losses if a primary user activity occurs. Under such rigid constraints, the reliable transmission of real time multimedia of a secondary user with an acceptable quality of service becomes challenging. Multimedia transmission in a cognitive system requires channel adaptive source and channel coding schemes. In order to address this problem, this thesis investigates and develops a novel joint source-channel coding (JSCC) approach. The proposed JSCC allows the dynamic generation of codes, which minimizes the end-to-end distortion. This JSCC is based on quantized frame expansions to introduce redundancy into transmitted data. An algorithm has been developed to determine the optimal trade-off between redundancy and quantization rate, under a constraint on channel capacity. The proposed approach does not require the communication of any overhead data between the transmitter and receiver. When compared to codes commonly used to deal with packet losses, simulation results indicate that the proposed JSCC can achieve lower distortion for secondary user’s transmissions in cognitive radio systems.

The world of power systems is ever changing; ever evolving. One such evolution was the advent of Phasor Measurement Units (PMUs). With the introduction of PMUs in the field, power system monitoring and control changed for the better. Innovative and efficient algorithms that used synchrophasors came to be written. To make these algorithms robust, it became necessary to remove errors that crept into the power system with time and usage. Thus the process of calibration became essential when practical decisions started being made based on PMU measurements. In the context of this thesis ‘calibration’ is the method used to estimate a correction factor which, when multiplied with the respective measurement, negates the effect of any errors that might have crept into them due to the instrument transformers located at the inputs of a PMU or the PMU device itself. Though this thesis mainly deals with the calibration of instrument transformers, work has been done previously for calibrating other components of a power system. A brief description of those methods have been provided along with a history on instrument transformer calibration. Three new methodologies for instrument transformer calibration have been discussed in details in this thesis. The first method describes how only voltage transformers can be calibrated by placing optimal number of good quality voltage measurements at strategic locations in the grid, in presence of ratio errors in the instrument transformers and Gaussian errors in the PMUs. The second method provides a way to calibrate all instrument transformers (both current and voltage) in presence of only one good quality voltage measurement located at the end of a tie-line. This method assumes that all the instrument transformers have ratio errors and the PMUs have quantization errors. The third method attains the same objective as the second one, with the additional constraint that the data obtained from the field may be contaminated. Thus, the third method shows how calibration of all the instrument transformers can be done with data that is intermittent and is therefore, the most practical approach (of the three) for instrument transformer calibration. / Master of Science