11 research outputs found
Computing shape using a theory of human stereo vision
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1980.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Bibliography: leaves 225-237.by William Eric Leifur Grimson.Ph.D
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Percolation, statistical topography, and transport in random-media
A review of classical percolation theory is presented, with an emphasis on novel applications to statistical topography, turbulent diffusion, and heterogeneous media. Statistical topography involves the geometrical properties of the isosets (contour lines or surfaces) of a random potential psi(x). For rapidly decaying correlations of psi, the isopotentials fall into the same universality class as the perimeters of percolation clusters. The topography of long-range correlated potentials involves many length scales and is associated either with the correlated percolation problem or with Mandelbrot's fractional Brownian reliefs. In all cases, the concept of fractal dimension is particularly fruitful in characterizing the geometry of random fields. The physical applications of statistical topography include diffusion in random velocity fields, heat and particle transport in turbulent plasmas, quantum Hall effect, magnetoresistance in inhomogeneous conductors with the classical Hall effect, and many others where random isopotentials are relevant. A geometrical approach to studying transport in random media, which captures essential qualitative features of the described phenomena, is advocated.Physic
The application of auditory signal processing principles to the detection, tracking and association of tonal components in sonar.
A steady signal exerts two complementary effects on a noisy acoustic environment:
one is to add energy, the other is to create order. The ear has evolved mechanisms to
detect both effects and encodes the fine temporal detail of a stimulus in sequences of
auditory nerve discharges. Taking inspiration from these ideas, this thesis investigates
the use of regular timing for sonar signal detection. Algorithms that operate on the
temporal structure of a received signal are developed for the detection of merchant
vessels. These ideas are explored by reappraising three areas traditionally associated
with power-based detection.
First of all, a time-frequency display based on timing instead of power is developed.
Rather than inquiring of the display, "How much energy has been measured at this
frequency? ", one would ask, "How structured is the signal at this frequency? Is this
consistent with a target? " The auditory-motivated zero crossings with peak amplitudes
(ZCPA) algorithm forms the starting-point for this study.
Next, matters related to quantitative system performance analysis are addressed, such
as how often a system will fail to detect a signal in particular conditions, or how much
energy is required to guarantee a certain probability of detection. A suite of optimal
temporal receivers is designed and is subsequently evaluated using the same kinds of
synthetic signal used to assess power-based systems: Gaussian processes and sinusoids.
The final area of work considers how discrete components on a sonar signal display,
such as tonals and transients, can be identified and organised according to auditory
scene analysis principles. Two algorithms are presented and evaluated using synthetic
signals: one is designed to track a tonal through transient events, and the other attempts
to identify groups of comodulated tonals against a noise background. A demonstration
of each algorithm is provided for recorded sonar signals
Aeronautical Engineering: a Continuing Bibliography with Indexes (Supplement 243)
This bibliography lists 423 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1989. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics
University of Nebraska at Omaha 2020-2021 Course Catalog
Located in one of America’s best cities to live, work and learn, the University of Nebraska at Omaha (UNO) is Nebraska’s premier metropolitan university. With more than 15,000 students enrolled in 200-plus programs of study, UNO is recognized nationally for its online education, graduate education, military friendliness, and community engagement efforts. Founded in 1908, UNO has served learners of all backgrounds for more than 100 years and is dedicated to another century of excellence both in the classroom and in the communit
Sixth NASTRAN (R) Users' Colloquium
Papers are presented on NASTRAN programming, and substructuring methods, as well as on fluids and thermal applications. Specific applications and capabilities of NASTRAN were also delineated along with general auxiliary programs
2021-2022 University of Nebraska at Omaha Catalog
Located in one of America’s best cities to live, work and learn, the University of Nebraska at Omaha (UNO) is Nebraska’s premier metropolitan university. With more than 15,000 students enrolled in 200-plus programs of study, UNO is recognized nationally for its online education, graduate education, military friendliness, and community engagement efforts. Founded in 1908, UNO has served learners of all backgrounds for more than 100 years and is dedicated to another century of excellence both in the classroom and in the communit