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Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson
The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson
Theses and Dissertations
The rational resolution analysis RRA is introduced and developed as a generalization of the integer, dilation multiresolution analyses MRA developed by Mallat and Meyer. Rational dilation factors are achieved by relaxing the condition on MRAs that successive approximation spaces be embedded. Conditions for perfect reconstruction are discussed and it is shown that perfect reconstruction is possible with specific constraints on the scaling function the scaling filter must have its roots on the unit circle. Furthermore, the required arrangement of the roots indicate the scaling function must be derived from a B-spline of some degree. It is proven the only compactly …
Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush
Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush
Theses and Dissertations
Existing missile/target encounter modeling and simulation systems focus on improving probability of kill models. Little research has been done to visualize these encounters. These systems can be made more useful to the engineers by incorporating current computer graphics technology for visualizing and animating the encounter. Our research has been to develop a graphical simulation package for visualizing both endgame and full fly-out encounters. Endgame visualization includes showing the interaction of a missile, its fuze cone proximity sensors, and its target during the final fraction of a second of the missile/target encounter. Additionally, this system displays dynamic effects such as the …
Breast Cancer Mass Detection Using Difference Of Gaussians And Pulse Coupled Neural Networks, Donald A. Cournoyer
Breast Cancer Mass Detection Using Difference Of Gaussians And Pulse Coupled Neural Networks, Donald A. Cournoyer
Theses and Dissertations
CAD, serving as a second reader, has been shown to improve the success of radiologists at detecting breast cancer. This thesis will develop a new algorithm to identify masses in mammograms. The system developed for this thesis will be capable of assisting a radiologist in making decisions.
Applications Of Unsupervised Clustering Algorithms To Aircraft Identification Using High Range Resolution Radar, Dzung Tri Pham
Applications Of Unsupervised Clustering Algorithms To Aircraft Identification Using High Range Resolution Radar, Dzung Tri Pham
Theses and Dissertations
Identification of aircraft from high range resolution (HRR) radar range profiles requires a database of information capturing the variability of the individual range profiles as a function of viewing aspect. This database can be a collection of individual signatures or a collection of average signatures distributed over the region of viewing aspect of interest. An efficient database is one which captures the intrinsic variability of the HRR signatures without either excessive redundancy typical of single-signature databases, or without the loss of information common when averaging arbitrary groups of signatures. The identification of 'natural' clustering of similar HRR signatures provides a …
A Single Chip Low Power Implementation Of An Asynchronous Fft Algorithm For Space Applications, Bruce W. Hunt
A Single Chip Low Power Implementation Of An Asynchronous Fft Algorithm For Space Applications, Bruce W. Hunt
Theses and Dissertations
A fully asynchronous fixed point FFT processor is introduced for low power space applications. The architecture is based on an algorithm developed by Suter and Stevens specifically for a low power implementation. The novelty of this architecture lies in its high localization of components and pipelining with no need to share a global memory. High throughput is attained using large numbers of small, local components working in parallel. A derivation of the algorithm from the discrete Fourier transform is presented followed by a discussion of circuit design parameters specifically, those relevant to space applications. The generic architecture is explained with …
Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain
Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain
Theses and Dissertations
A new atmospheric turbulence screen generator is developed for use in performance calculations of adaptive optics systems valid over a wide range of atmospheric turbulence parameters. The screen generator accounts for diffraction effects caused by weak turbulence and incorporates the phase, amplitude, and cross statistics of the perturbed optical field. The wavefront's phase and amplitude perturbations are taken from the correlation functions developed by Lee and Harp and the cross correlation of the phase and amplitude derived in this thesis. The screen generator uses a modal representation to perform a Fourier series expansion of the wavefront phase and amplitude over …
Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler
Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler
Theses and Dissertations
An understanding of spontaneous emission processes within microcavities is crucial in addressing the need to make tomorrow's microlasers more efficient. One approach to improving the device efficiency is to reduce the threshold input energy at which lasing begins to occur. It has been suggested that the threshold in a microcavity laser can be decreased by increasing the fraction of spontaneous emission into the lasing mode, this can be accomplished by preferentially coupling the gain medium of the laser to the electromagnetic cavity mode of interest. It therefore becomes necessary to understand the mechanism by which this coupling takes place. This …
Parameter Estimation For Real Filtered Sinusoids, Daniel R. Zahirniak
Parameter Estimation For Real Filtered Sinusoids, Daniel R. Zahirniak
Theses and Dissertations
This research develops theoretical methods for parameter estimation of filtered, pulsed sinusoids in noise and demonstrates their effectiveness for Electronic Warfare EW applications. Within the context of stochastic modeling, a new linear model, parameterized by a set of Linear Prediction LP coefficients, is derived for estimating the frequencies of filtered sinusoids. This model is an improvement over previous modeling techniques since the effects of the filter and the coefficients upon the noise statistics are properly accounted for during model development. From this linear model, a relationship between LP coefficient estimation and Maximum Likelihood ML frequency estimation is derived and several …
Optimization Considerations For Adaptive Optics Digital Imagery Systems, Robert T. Brigantic
Optimization Considerations For Adaptive Optics Digital Imagery Systems, Robert T. Brigantic
Theses and Dissertations
This dissertation had three objectives. The first objective was to develop image quality metrics that characterize Adaptive Optics System (AOS) performance. The second objective was to delineate control settings that maximize AOS performance. The third objective was to identify and characterize trade-offs between fully and partially compensated adaptive. For the first objective, three candidate image quality metrics were considered: the Strehl ratio, a novel metric that modifies the Strehl ratio by integrating the modulus of the average system optical transfer function to a 'noise-effective-cutoff' frequency at which some specified image spectrum signal-to-noise-ratio level is attained, and the noise-effective-cutoff frequency. It …
On-Line System Identification For Control System Applications In Particle Accelerators, Mahesh Chowdhary
On-Line System Identification For Control System Applications In Particle Accelerators, Mahesh Chowdhary
Dissertations, Theses, and Masters Projects
Particle accelerators require a number of feedback systems in order to stabilize a variety of parameters. The Continuous Electron Beam Accelerator at Thomas Jefferson National Accelerator Facility presents a unique set of control and identification problems. This accelerator produces a continuous electron beam with energies between 0.5 and 4.0 GeV to be delivered to the experimental halls. In order to meet stringent beam quality requirements specified by the experimental halls, the position and the energy of the electron beam needs to stabilized at various locations in the accelerator.;A number of noise measurement tests were conducted at various locations in the …