Astrophysical models that address stellar energy generation and nucleosynthesis require a considerable amount of input from nuclear physics and are very sensitive to the detailed structure of nuclei, both stable and unstable. Radioactive nuclei play a dominant role in several stellar environments such as supernovae, X-ray bursts, novae etc. and nuclear data are important in the interpretation of these phenomena. When carbon, nitrogen and oxygen isotopes are present in substantial quantities in a star of sufficient mass, the fusion of four hydrogen nuclei to form a helium nucleus proceeds via the CNO cycles. Energy release in the CNO cycles is limited by the long lifetimes of 14O and 15O. In explosive stellar scenarios such as X-ray bursts, the energy output is very large, suggesting a breakout from the CNO cycles. 15O(α,γ)19Ne is the first reaction that breaks out of the CNO cycle. Nuclear structure information on high lying states in 19Ne is required to calculate the rate of the 15O(α,γ)19Ne reaction. This work focuses on the study of states in 19Ne above 3.53 MeV. The lifetimes of five states in 19Ne above 3.53 MeV were measured in this work. The states in 19Ne were populated via the 3He(20Ne,α)19Ne reaction at a beam energy of 34 MeV. The lifetimes were measured using the Doppler Shift Attenuation Method. The lifetimes of five states were measured and an upper limit was set on the lifetime of a sixth state. Three of the measurements are the most precise thus far. The lifetimes of the other three states agree with the values of the only other measurement of the lifetimes of these states. An upper limit on the rate of the 15O(α,γ)19Ne reaction was calculated at the 90% confidence level using the measured lifetimes. The contributions to the 15O(α,γ)19Ne reaction rate from several states in 19Ne at different stellar temperatures are discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Analyses are performed on the potential of using radio-frequency signals from massive LEO satellite constellations. This work aids in the creation of a navigation system independent of current GNSS. A tightly-coupled carrier Doppler shift/INS filter is developed to determine the feasibility of using signals of opportunity from LEO satellites for navigation purposes. This portion of the work makes two major contributions to the field of satellite-based radio-navigation systems. The first contribution is an analysis that shows GNSS-like position accuracy is possible using only INS measurements and carrier Doppler shift from LEO communication constellations. The second contribution is that INS quality, signal availability, and constellation design can significantly impact the navigation accuracy of a carrier Doppler shift/INS Kalman filter. An analysis of the costs and benefits of using model replacement over a Markov model in the dynamic propagation step of a tightly-coupled carrier Doppler shift/INS Kalman filter is performed in the next part of this work. This portion of the work makes contributions to the field of satellite-based radio-navigation systems. The main contribution is an analysis that shows Gauss-Markov models can be used instead of model replacement without increasing navigation error. Next, a DOP analysis is developed for systems using pseudorange and carrier Doppler shift measurements in point-solution batch filters that do not rely on INS data or dynamic propagation. This section's contributions to the field of satellite-based radio-navigation systems include a combined pseudorange and carrier Doppler shift DOP analysis using a novel DOP metric and an example of how to use the DOP analysis to identify the constellation characteristics, such as alternating ascending and descending nodes, that the OneWeb constellation could change to increase navigation accuracy. / Doctor of Philosophy / This dissertation presents research on using large communication satellite constellations as an independent backup to GPS. Simulated data are used to study the feasibility and navigation accuracy of such a system. Also investigated are different implementations of the algorithms used to navigate. Finally, a general analysis is developed to quickly approximate the navigation accuracy of a system that uses multiple measurement types.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / This paper addresses the air-to-ground communication problem, where multiple transmit antennas are used on the aircraft to combat multi-path interference. The channel is assumed to have a line-of-sight component and a single ground reflection. Multiple input multiple output (MIMO) techniques can be used in this situation, to increase the reliability and data rate. In this paper we discuss how the MIMO channel capacity changes, with the aircraft antenna configuration, altitude, velocity, range, and a number of other parameters. For comparison, the MIMO results are compared to systems which have single antennas at the transmitter, at the receiver, or at both ends.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / NASA's Space Network (SN) provides both single access (SA) and multiple access (MA) services through a pre-scheduling system. Currently, a user's spacecraft is incapable of receiving service unless prior scheduling occurred with the control center. NASA is interested in efficiently utilizing the time between scheduled services. Thus, a demand assignment multiple access (DAMA) service study was conducted to provide a solution. The DAMA service would allow the user's spacecraft to initiate a service request. The control center could then schedule the next available time slot upon owner approval. In this paper, the basic DAMA service request design and integration is presented.

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Airborne CW doppler proximity sensors are very sensitive, but leaks precise height measurement. It may be possible to estimate the heigth at the terminal phase (the case where the sensor is at a heigth close to ground) precisely by using the doppler shift and amplitude information. The thesis includes this novel concept with theoritical analysis and simulation results.

Diagnostic measurements play a vital role in experiments. Without them we would be in the dark with no way of knowing what was happening; of understanding the processes and behaviour occurring; or even of judging the success or failure of our experiments. The development of fusion plasma devices is no different. In this thesis we concentrate on visible spectroscopy based diagnostics: examining the techniques for measurement and analysis; the breadth of plasma parameters that can be extracted from the spectroscopic data; and how the application of these diagnostic techniques gives us a broader picture of the plasma and the events taking place within. Techniques are developed and applied to plasmas in three fusion experiments, EXTRAP T2R, ASDEX Upgrade and JET. The diagnostic techniques exploit different features of the measurements of the emitted photons to obtain various useful plasma parameters. Determination of the ion temperature and rotation velocity of oxygen impurity ions in the EXTRAP T2R plasma is achieved through measurement and analysis of, respectively, the Doppler broadening and the Doppler wavelength shift of visible wavelength atomic spectral lines. The evolution of the temperature and rotation is studied as a function of the discharge parameters, in particular looking at the effect of applying active feedback control schemes to the resistive wall modes and/or pulsed poloidal current drive. Measurements of multiple ionisation stages are used to estimate radial profiles of the toroidal rotation and the ion temperature and correlations between the ion rotations and the rotation velocities of tearing modes are also established. Radial profiles of the emissivity and density (or concentration) of the oxygen ions are obtained by means of measurements of the spectral line intensities on a small array of linesof- sight through the plasma. Changes to the profiles for different plasma schemes and the implications for particle transport are investigated. The derived emissivity profiles are used in the analysis for some of the other spectroscopic diagnostics. Spectral line intensity measurements (in this case of neutral ions) are also the basis for calculations of both the electron temperature and the particle fluxes at the plasma edge. The latter is an indicator of the degree and type of interaction between the plasma and the surrounding surfaces. Particle fluxes of the operating gas hydrogen and of chromium and molybdenum impurities are investigated in EXTRAP T2R for different operating scenarios, in particular changes in the metallic influx with the application of active feedback mode control are examined along with the correspondence between spectroscopic and collector probe results. In the ASDEX Upgrade divertor estimates of the particle flux of the deuterium operating gas are also made through analysis of spectral intensities. Molecular D2 band structure is explored in addition to the Balmer Dα spectral line intensity to acquire both atomic and molecular particle fluxes, investigate the contribution of the dissociating D2 to the Dα line and study the effect of changes in the divertor. Analysis of the D2 molecular band structure (the relative intensities of the rotational lines and vibrational bands) also enables calculation of the upper state rotational and ground state vibrational temperatures. The locations of emitting atomic ions in JET are estimated from Zeeman splitting analysis of the structure of their spectral lines. The measurement and analysis of visible wavelength light is demonstrated to be a sensitive diagnostic tool in the quest for increased knowledge about fusion plasmas and their operating scenarios. / QC 20100810

In this study, a method to predict vehicle pass-by noise in a finite dimensioned, semi-anechoic chamber with chassis dynamometer has been developed. Vehicle noise has been modeled as the summation of the individual contributions regarding the principal noise components, namely, engine including air intake, front tire and rear tire noises. This method employs wave propagation, Doppler shift, and time delay in the estimation of the sound pressure due to each component at points of interest specified by relevant standards. An acoustical simulation model has been developed in MaTLAB environment. The model has been applied on two different vehicles. Finally, the predicted sound pressure values are found to be in good agreement with the corresponding values acquired in outdoor measurements addressed in ISO 362 for vehicle pass-by noise measurement standard.

This thesis focuses on analysis, classification, simulation and assessment of the signal fading in the scope of terrestrial digital television reception. This is a phenomenon associated with signal multipath propagation caused by the reflection, dispersion and diffraction of electromagnetic waves in interaction with relief and artificial obstacles. Wave propagation issues in a specific landscape are not the central theme of this project. Signal transmission between the transmitter and receiver is defined by channel profile models. Attention is directed not only to static reception but also to portable and mobile reception. Simulation of this phenomenon takes place in the software environment of MATLAB. In the framework of this project program fundament was created which allows simulate the signal processing across the entire communication chain of television broadcasting, including its transmitting and receiving parts.

Thanks to its improved capabilities, the Multiple Input Multiple Output (MIMO) radar is attracting the attention of researchers and practitioners alike. Because it transmits orthogonal or partially correlated waveforms, this emerging technology outperformed the phased array radar by providing better parametric identifiability, achieving higher spatial resolution, and designing complex beampatterns. To avoid jamming and enhance the signal to noise ratio, it is often interesting to maximize the transmitted power in a given region of interest and minimize it elsewhere. This problem is known as the transmit beampattern design and is usually tackled as a two-step process: a transmit covariance matrix is firstly designed by minimizing a convex optimization problem, which is then used to generate practical waveforms. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method maps easily generated Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability density function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. The second part of this thesis covers the topic of target parameter estimation. To determine the reflection coefficient, spatial location, and Doppler shift of a target, maximum likelihood estimation yields the best performance. However, it requires a two dimensional search problem. Therefore, its computational complexity is prohibitively high. So, we proposed a reduced complexity and optimum performance algorithm which allows the two dimensional fast Fourier transform to jointly estimate the spatial location and Doppler shift. To assess the performance of the proposed estimators, the Cramér-Rao Lower Bound (CRLB) is derived. Simulation results show that the mean square estimation error of the proposed estimators achieve the CRLB. Keywords: Collocate antennas, multiple-input multiple-output (MIMO) radar, Finite alphabet waveforms, Hermite polynomials, Reflection coefficient, Doppler, Spatial location, Cramér-Rao Lower Bound.