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Articles 421 - 426 of 426
Full-Text Articles in Signal Processing
Determination Of Bistatic Radar Clutter Power From Topographic Data, Clyde R. Heddings
Determination Of Bistatic Radar Clutter Power From Topographic Data, Clyde R. Heddings
Theses and Dissertations
The purpose of this research was to develop a procedure for estimating the average bistatic radar clutter power from a topographic map using rough surface scattering theory. First, the terrain in the radar target area was divided into sub regions having homogeneous characteristics. A joint Gaussian distribution for the surface heights was fitted from the information contained in the topographic map contour lines for each homogeneous area. From these distributions, the normalized radar cross section for each terrain area was determined. The clutter power for each range cell was then determined via a modified radar range equation. The procedure was …
Sensing Refractive Turbulence Profiles Using Wave Front Slope Measurements From Two Reference Sources, Michael D. Rejack
Sensing Refractive Turbulence Profiles Using Wave Front Slope Measurements From Two Reference Sources, Michael D. Rejack
Theses and Dissertations
This thesis examines a remote sensing technique for measuring the atmospheric structure constant as a function of altitude by performing spatial correlation or wavefront sensor measurements. Two point sources are used to irradiate two wavefront sensors in the aperture plane of an optical system. The geometric relationship between the sources and the sensors gives rise to crossed optical paths. At the point where the paths cross, the correlation value of the turbulence contributions will be at a peak. The correlation is shown to be mathematically related to the structure constant in terms of an integral of the structure constant multiplied …
Image Segmentation Using Affine Wavelets, Steven E. Smiley
Image Segmentation Using Affine Wavelets, Steven E. Smiley
Theses and Dissertations
This thesis discusses the use of the multiresolution representation and Radial Basis Function (RBF) neural networks to segment both FLIR and SAR imagery. The multiresolution approximation coefficients are used as features into the RBF network which learns to distinguish between different cultural and natural regions or objects. The wavelets used are Mallat's spline wavelet and Daubechies' compactly supported wavelets. Additionally, this thesis provides an explanation of wavelets in a tutorial manner. It introduces wavelet theory and discusses two different approaches to generating the multiresolution or wavelet representation.
Steady-State Production And Quenching Of Br(2P½), Ralph F. Tate
Steady-State Production And Quenching Of Br(2P½), Ralph F. Tate
Theses and Dissertations
The spin orbit relaxation of atoms has been investigated in a steady state infrared fluorescence experiment. A CW argon ion laser operating at 488 nm was used to photodissociate gas-phase Br into equal quantities of Bromine and Bromine atoms. The resulting 2.7 µm emission was observed as a function of added quenching gas. A steady-state analysis was used to determine quenching rates for SF6, N2, O2, He, Ne, Ar, Kr, and Xe, relative to quenching by the parent molecule. Limitations in the apparatus prevented determination of the quenching rate coefficient for Br2. …
A Vision System Model, Erik J. Fretheim
A Vision System Model, Erik J. Fretheim
Theses and Dissertations
This dissertation provides four major contributions to the field of vision research. The first contribution is a general vision system model. The model, which blends biological as well as technological methods into a coherent approach to vision, will provide a basis for implementing vision systems. The second contribution of this dissertation is to demonstrate particular implementations of portions of the model. These implementations will include methods for using Gabor wavelets in edge detection, in preprocessing images for use as feature vectors in backpropagation neural networks, and as basis functions in a recognition/reconstruction network, as well as methods for integrating color …
Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey
Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey
Theses and Dissertations
This thesis investigated the potential of fractal dimension estimation for segmenting high resolution polarimetric synthetic aperture radar. The data used during this research were collected with the Advanced Detection Technology Sensor (ADTS) developed by Massachusetts Institute of Technology Lincoln Laboratory with Defense Advanced Research Projects Agency funding. ADTS is a fully polarimetric calibrated 35 GHz SAR with one foot impulse response. A method of applying the correlation dimension algorithm developed by Grassberger and Procaccia for estimating the dimension of time series data was implemented to estimate the correlation dimension of polarimetric SAR data. A threshold sensitivity study was performed to …