Thesis (Ph. D.)--Ohio State University, 1981. / Includes vita. Includes bibliographical references (leaves 165-171). Available online via OhioLINK's ETD Center.

Motion blur is one important method for increasing the visual quality of real-time applications. This is increasingly true in the area of interactive applications, where designers often seek to add graphical flair or realism to their programs. These applications often have animated characters with a polygonal mesh wrapped around an animated skeleton; and as the skeleton moves the mesh deforms with it. This thesis presents a method for adding a geometric motion blur to a deforming polygonal mesh. The scheme presented tracks an object's motion silhouette, and uses this to create a polygonal mesh. When this mesh is added to the scene, it gives the appearance of a motion blur on a single object or particular character. The method is generic enough to work on nearly any type of moving polygonal model. Examples are given that show how the method could be expanded and how changes could be made to improve its performance.

No description available.

The purpose of the essay is to illustrate the differences in understanding and comprehension of time among the characters in the novel Hard Times. These contrasting differences are then argued to compose a crtisism of the industrial society.

In what sense, if any, is time related to nature? In this dissertation, I argue that Aristotle's Treatise on Time (<italic>Physics</italic> iv 10-14) must be read in light of his foregoing discussion of nature (<italic>phusis</italic>) in Physics i-iv 9. Thus, Aristotle's definition of time (<italic>chronos</italic>) in Physics iv 11, that time is the number (<italic>arithmos</italic>) of motion (<italic>kinesis</italic>) with respect to before and after (219b1), is highly contextualized and as such must be understood as not only derivative of both Aristotle's definition of nature, as the inner capacity for motion and rest (192b13-22), and of his explanation of kinêsis, but also parallel to his analyses of the infinite (<italic>apeiron</italic>), place (<italic>tops</italic>), and void (<italic>kenos</italic>). What is more, I bring attention to the fact that Aristotle's understanding of nature is shaped fundamentally by the distinction he makes in the <italic>Physics</italic> and elsewhere (<italic>Metaphysics</italic> iv) between potentiality (<italic>dunamis</italic>) and actuality (<italic>entelecheia</italic>). With this in mind, I distinguish between the potential for time and actual time in Aristotle and conclude that the human being, along with actual motion, is both the necessary and sufficient condition for actual time on his account. Time, for Aristotle, then, results from an interaction between two or more parts of nature. It is not an a priori substance to be examined qua itself. My conclusions, therefore, offer a solution to those who read Aristotle's Treatise on Time as a confused inquiry, i.e. one that oscillates between a theory of knowledge and a theory of reality and combines what many believe to be Aristotle's characteristic realism with idealism. Finally, I use these conclusions to show a likeness between the account of time I attribute to Aristotle and what I suggest to be a return to thinking about time as derivative of a theory of nature in early Schellingian <italic>Naturphilosophie</italic>. / McAnulty College and Graduate School of Liberal Arts; / Philosophy / PhD; / Dissertation;

The purpose of this study is to develop experimental techniques to characterize typical interconnect discontinuities, including bends, steps, T junctions, vias and pads, which are the most commonly encountered interconnections in high speed digital integrated circuits, hybrid and monolithic microwave circuits and electronic packages. The time domain reflection response of these elements is used to classify the interconnect discontinuities as distributed discontinuity elements or as lumped elements depending upon the reflected waveform. For the cases of general distributed discontinuities including bends, steps and T junctions, the distributed equivalent circuit model is characterized by the time dependent impedance profile which is extracted from the time domain reflection measurements. By using known inverse scattering techniques implemented in terms of a new algorithm based on the transfer scattering matrix method of incremental uniform sections, this nonuniform impedance profile is extracted and is used to construct distributed element circuit models to represent the interconnect discontinuities. A circuit model consisting of lumped/distributed elements, is also developed for the interconnect discontinuities which is intended to combine the accuracy of the distributed model with the simulation efficiency of the lumped models. This hybrid mode reduces computer simulation time when used as a net list for general purpose circuit simulators, such as SPICE. For the case of discontinuities modelled as lumped elements, such as vias and wiring pads, closed form equations based on the transfer scattering matrix solution are derived and used to extract the lumped electrical parameters of these elements from the time domain reflection waveform. All of these lumped, distributed and hybrid models are validated by comparing the time domain simulation results with Time Domain Reflectrometer ( TDR ) measurements. A procedure for extracting the excess inductances and capacitances associated with the general discontinuities from the synthesized nonuniform impedance profile or the distributed model is also presented in this report. These results for excess lumped inductances and capacitances show close agreement with the published results for these structures which are based on the electromagnetic computation of excess currents and charges and frequency domain measurements. Finally, some typical cases demonstrating the effects of interconnect discontinuities in high speed clocking systems are presented and the procedure for reducing the reflections and transmission noise voltage by chamfering the bends and junctions is described. / Graduation date: 1992

Diagnostic ultrasound is a non-invasive image modality commonly used to diagnose multiple diseases. Sonographers and physicians have to devote a substantial amount of time learning how the combination of the various parameters of the ultrasound system affects the resulting ultrasound information among its different modalities. The primary objective of this thesis is to create a mechanistic ultrasound simulation method that could achieve near real-time performance to teach and train sonographers and physicians. A major bottleneck for achieving real-time performance with available tools was the transducer field simulation method that uses the impulse response technique. To address this problem a new simulation approach was developed. This project was realized in a three-phase approach, specifically to simulate spectral Doppler. In first place, it was shown that is possible to mechanistically simulate the sample volume power distribution using a novel method based on an array of point sources to represent the transducer geometry. Secondly, by comparison with the Field II results, it was demonstrated that the time-domain signal could be closely reproduced using point sources. Finally, by treating the array of point sources as point receivers, the received signal was compared with the results from Field II, and again, good agreement was achieved. Simulation results were compared against the standard simulation method for a number of examples involving steady and pulsatile flow, for which the spectrograms were compared against Field II. Also presented are preliminary results obtained using the point source approach to simulate B-mode images. As well, methods are described for generating Doppler spectrograms from the results of computation fluid dynamics velocity fields obtained in realistic arterial geometrical models. It is pointed out that the successful simulation of the time domain signal opens the possibility for real-time simulation of other ultrasound modes.

Diagnostic ultrasound is a non-invasive image modality commonly used to diagnose multiple diseases. Sonographers and physicians have to devote a substantial amount of time learning how the combination of the various parameters of the ultrasound system affects the resulting ultrasound information among its different modalities. The primary objective of this thesis is to create a mechanistic ultrasound simulation method that could achieve near real-time performance to teach and train sonographers and physicians. A major bottleneck for achieving real-time performance with available tools was the transducer field simulation method that uses the impulse response technique. To address this problem a new simulation approach was developed. This project was realized in a three-phase approach, specifically to simulate spectral Doppler. In first place, it was shown that is possible to mechanistically simulate the sample volume power distribution using a novel method based on an array of point sources to represent the transducer geometry. Secondly, by comparison with the Field II results, it was demonstrated that the time-domain signal could be closely reproduced using point sources. Finally, by treating the array of point sources as point receivers, the received signal was compared with the results from Field II, and again, good agreement was achieved. Simulation results were compared against the standard simulation method for a number of examples involving steady and pulsatile flow, for which the spectrograms were compared against Field II. Also presented are preliminary results obtained using the point source approach to simulate B-mode images. As well, methods are described for generating Doppler spectrograms from the results of computation fluid dynamics velocity fields obtained in realistic arterial geometrical models. It is pointed out that the successful simulation of the time domain signal opens the possibility for real-time simulation of other ultrasound modes.

This thesis develops a novel robust periodogram method for detecting long memory. Though many test for long memory are based on the idea of linear regression, there exists no results in statistical literature on utilizing the robust regression methodology for detection of long memory. The advantage of the robust regression is a substantially less sensitivity to atypical observations or outliers, compared to the classical regression that is based on the least squares method. The thesis suggests two versions of the robust periodogram methods based on the least quan- tile and the least trimmed methods. The new robust periodogram methods are shown to provide smaller bias in long memory estimation when compared with the classical periodogram method. However, variability of estimation is increased. Therefore, we develop the bootstrapped modification of the new robust periodogram methods to reduce variability of estimation. The new bootstrapped modi¯cations of the robust periodogram tests substantially reduce variance of estimation and provides a competitively low bias. All proposed robust methods are illustrated by simulations and the case studies on currency exchange rates, and comparative analysis with other existing tests for long memory is carried out.

This thesis develops a novel robust periodogram method for detecting long memory. Though many test for long memory are based on the idea of linear regression, there exists no results in statistical literature on utilizing the robust regression methodology for detection of long memory. The advantage of the robust regression is a substantially less sensitivity to atypical observations or outliers, compared to the classical regression that is based on the least squares method. The thesis suggests two versions of the robust periodogram methods based on the least quan- tile and the least trimmed methods. The new robust periodogram methods are shown to provide smaller bias in long memory estimation when compared with the classical periodogram method. However, variability of estimation is increased. Therefore, we develop the bootstrapped modification of the new robust periodogram methods to reduce variability of estimation. The new bootstrapped modi¯cations of the robust periodogram tests substantially reduce variance of estimation and provides a competitively low bias. All proposed robust methods are illustrated by simulations and the case studies on currency exchange rates, and comparative analysis with other existing tests for long memory is carried out.