In the event of large scale public radiation exposures, a means of rapid personal radiation dosimetry would provide a valuable tool for environmental and human health protection as well as for possible criminal investigations (in the event of terrorist dirty bombs). This thesis describes a method of sensitizing synthetic quartz oscillators, found in many timekeeping devices such as watches and cellular phones, to function as radiation dosimeters. Experiments on the sensitization of synthetic quartz crystals from watch oscillators were performed by subjecting the quartz to thermal treatments in the range of 200°C to 800°C. The lengths of treatments ranged from numerous one hour cycles to week-long single anneal treatments and combinations of the two. All treatments were designed to mimic factors that are known to cause sensitization in geologic quartz grains (Botter-Jensen, Larsen et al., 1995). The greatest sensitization was observed in crystals treated to 800°C for one week and then subjected to two series of heating, irradiation, and optical exposures. These crystals were able to recover doses as low as 0.5 Gray at an error within 10% of the delivered dose. This work is the first stage of development for creating dual purpose quartz oscillator-dosimeters which could be used in watches, cellular phones, clocks, and nearly all equipment requiring a timekeeping component. In the future, experiments should be conducted to show definitively that crystals still function as 32.768 kHz oscillators after annealing and that oscillators trap charge while in operation. / Thesis / Master of Science (MSc)

A study on phase synchronization in large populations of nonlinear dynamical systems is presented in this thesis. Using the well-known Rossler system as a prototypical model, phase synchronization in one oscillator with periodic external forcing and in two-coupled nonidentical oscillators was explored at first. The study was further extended to consider three-dimensional lattices and globally coupled populations of nonidentical oscillators, in which the mathematical formulation that represents phase synchronization in the generalized N-coupled Rossler system was derived and several computer programs that perform numerical simulations were developed. The results show the effects of coupling dimension, coupling strength, population size, and system parameter on phase synchronization of the various Rossler systems, which may be applicable to studying phase synchronization in other nonlinear dynamical systems as well.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / The uncertainty in the gain of voltage controlled crystal oscillators (VCXOs) used in the implementation of certain analog phase-locked loops (PLLs) suggests some form of automatic tuning algorithm, both for pretuning and during operation. This paper proposes an adaptive PLL (APLL) algorithm to fill this need for PLLs used in the recovery of tones in noise. This algorithm makes use of a resonant error algorithm to remove the effects of VCXO noise, measurement noise, and parasitic poles. Both classical convergence theorems and robustness theorems that indicate the functionality of the proposed algorithm are given. Finally, the implementation of this algorithm is considered.

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This work deals with the application of supermathematics to supersymmetrical problems arising in physics. Some recent developments are presented in detail. A reduction scheme for general supermanifolds to vector bundles is presented, which significantly simplifies their mathematical treatment in a physical context. Moreover, some applications of this new approach are worked out, such as the Fermi oscillator.

With conventional CMOS technologies approaching their scaling limits, researchers are actively investigating alternative technologies for ever increasing computing and mobile demand. A number of different technologies are currently being studied by different research groups. In the last decade, one-dimensional (1D) carbon nanotubes (CNT), graphene, which is a two-dimensional (2D) natural occurring carbon rolled in tubular form, and zero-dimensional (0D) fullerenes have been the subject of intensive research. In 2008, HP Labs announced a ground-breaking fabrication of memristors, the fourth fundamental element postulated by Chua at the University of California, Berkeley in 1971. In the last few years, the memristor has gained a lot of attention from the research community. In-depth studies of the memristor and its analog behavior have convinced the community that it has the potential in future nano-architectures for optimization of high-density memory and neuromorphic computing architectures. The objective of this thesis is to explore memristors for analog and mixed-signal system design using Simscape. This thesis presents a memristor model in the Simscape language. Simscape has been used as it has the potential for modeling large systems. A memristor based programmable oscillator is also presented with simulation results and characterization. In addition, simulation results of different memristor models are presented which are crucial for the detailed understanding of the memristor along with its properties.

<p> We study a many particle system contained within a harmonic oscillator potential, with the single particle spacings equispaced and nondegenerate. We consider either fermions or bosons within this harmonic oscillator potential and derive the density of states for this system, with low excitation energy corrections. We extend our method for more than one species of fermions or bosons within this harmonic oscillator potential and compare our results with number-theoretic techniques. We move on to the degenerate harmonic oscillator potential and show that, for a fermion system, shell effects are contained within low excitation energy terms. We attempt to arrive at the density of states for an infinite number of bosons within the same potential. </p> / Thesis / Master of Science (MSc)

Phase noise from radio frequency (RF) oscillators is one of the major limiting factors affecting communication system performance. Phase noise directly effects short-term frequency stability, Bit-Error-Rate (BER), and phase-locked loop adjacent-channel interference. RF oscillator circuits contain at least one active device, usually a transistor. The active device has noise properties which generally dominate the noise characteristic limits of an oscillator. Since all noise sources, except thermal noise, are generally proportional to average current flow through the active device, it is logical that reducing the current flow through the device will lead to lower noise levels. A theory based on the time-varying properties of oscillators proposes that narrowing the current pulse width in the active device will decrease the time that noise is present in the circuit and therefore, decrease phase noise even further. The time-domain waveforms and phase noise of an active-biased 700MHz oscillator are analyzed, showing heavy saturation and high harmonic content. Redesigns of the example oscillator in active-bias and four-resistor-bias configurations show improved phase noise and lower harmonic levels at the output. Five oscillator designs of each bias configuration, each having a different pulse width, are simulated. As predicted by the theory, the narrowest current pulse corresponds to the lowest phase noise of the simulated oscillators. / Master of Science

Oscillator phase noise is an important factor in designing radio frequency (RF) communications hardware. Phase noise directly contributes to adjacent-channel interference and an increase in bit error rate (BER). Understanding the operation of an oscillator can help with the oscillator design process. Also, the understanding of the noise processes within an oscillator can add insight to the design process, allowing an intelligent low-noise design. It will be shown that although simulation software can be helpful, the understanding of the oscillator operation is a valuable tool in the design process. Oscillator design will be discussed, and then the noise processes of the oscillator will be investigated. A new method of decomposing shot noise into in-phase and quadrature components will be discussed. The noise processes discussed for a non-saturating bipolar junction transistor (BJT) Colpitts oscillator will be extended to the case of a saturating BJT Colpitts oscillator. This new method gives insight into the design of low-noise oscillators, and provides guidelines for design of low-noise oscillators. Example oscillators will support the theory and low-noise design guidelines. It will be seen that although designing an oscillator to saturate can provide a stable output level over a wide bandwidth, the added noise production may degrade the performance of the oscillator through both a lower effective Q and restricted signal level compared to the noise. / Master of Science

For decades, the quartz crystal has been used for precise frequency control. In the increasingly popular field of wireless communications, available frequency spectrum is becoming very limited, and therefore regulatory agencies have imposed tight frequency stability requirements. There are generally two techniques for controlling the stability of a crystal oscillator with temperature variations of the environment. They are temperature control and temperature compensation. Temperature control involves placing the sensitive components of an oscillator in a temperature stable chamber. Usually referred to as an oven-controlled crystal oscillator (OCXO), this technique can achieve very good stability over wide temperature ranges. Nevertheless, its use in miniature battery powered electronic devices is significantly limited by drawbacks such as cost, power consumption, and size. Temperature compensation, on the other hand, entails using temperature dependent circuit elements to compensate for shifts in frequency due to changes in ambient temperature. A crystal oscillator that uses this frequency stabilization technique is referred to as a temperature-compensated crystal oscillator (TCXO). With little added cost, size, and power consumption, a TCXO is well suited for use in portable devices. This paper presents the theory of temperature compensation, and a procedure for designing a TCXO and predicting its performance over temperature. The equivalent electrical circuit model and frequency stability characteristics for the AT-cut quartz crystal are developed. An oscillator circuit topology is introduced such that the crystal is operated in parallel resonance with an external capacitance, and equations are derived that express the frequency stability of the crystal oscillator as a function of the crystal's capacitive load. This relationship leads to the development of the theory of temperature compensation by a crystal's external load capacitance. An example of the TCXO design process is demonstrated with the aid of a MATLAB script. / Master of Science