Fluid passage-time calculation in large Markov models

Recent developments in the analysis of large Markov models facilitate the fast approximation of transient characteristics of the underlying stochastic process. So-called fluid analysis makes it possible to consider previously intractable models whose underlying discrete state space grows exponentially as model components are added. In this work, we show how fluid approximation techniques may be used to extract passage-time measures from performance models. We focus on two types of passage measure: passage-times involving individual components; as well as passage-times which capture the time taken for a population of components to evolve. Specifically, we show that for models of sufficient scale, passage-time distributions can be well approximated by a deterministic fluid-derived passage-time measure. Where models are not of sufficient scale, we are able to generate approximate bounds for the entire cumulative distribution function of these passage-time random variables, using moment-based techniques. Finally, we show that for some passage-time measures involving individual components the cumulative distribution function can be directly approximated by fluid techniques

Geomorphological similarity and uniqueness

Remote sensing technology, particularly the development of satellite imagery, has given geomorphology a valuable tool for the study of large area, regional landscapes. The small scale large area format of LANDSAT and other satellite imagery reduces the amount of detailed information provided for a given region. This can be an advantage for regional study as much of the local information that is filtered out tends to be detail which, while significant in small area studies, could mask regional patterns

Prediction and reduction of rotor broadband noise

Prediction techniques which can be or have been applied to subsonic rotors, and methods for designing helicopter rotors for reduced broadband noise generation are summarized. It is shown how detailed physical models of the noise source can be used to identify approaches to noise control

Low energy ionization of argon atoms by argon atoms

Ionization cross section for production of electrons by collisions between neutral argon atom

Integrated control and health management. Orbit transfer rocket engine technology program

To insure controllability of the baseline design for a 7500 pound thrust, 10:1 throttleable, dual expanded cycle, Hydrogen-Oxygen, orbit transfer rocket engine, an Integrated Controls and Health Monitoring concept was developed. This included: (1) Dynamic engine simulations using a TUTSIM derived computer code; (2) analysis of various control methods; (3) Failure Modes Analysis to identify critical sensors; (4) Survey of applicable sensors technology; and, (5) Study of Health Monitoring philosophies. The engine design was found to be controllable over the full throttling range by using 13 valves, including an oxygen turbine bypass valve to control mixture ratio, and a hydrogen turbine bypass valve, used in conjunction with the oxygen bypass to control thrust. Classic feedback control methods are proposed along with specific requirements for valves, sensors, and the controller. Expanding on the control system, a Health Monitoring system is proposed including suggested computing methods and the following recommended sensors: (1) Fiber optic and silicon bearing deflectometers; (2) Capacitive shaft displacement sensors; and (3) Hot spot thermocouple arrays. Further work is needed to refine and verify the dynamic simulations and control algorithms, to advance sensor capabilities, and to develop the Health Monitoring computational methods

LANDSAT application of remote sensing to shoreline-form analysis

There are no author-identified significant results in this report

Inferences on Criminality Based on Appearance

In our research study, we tested whether people can tell if someone is a criminal or not based on a photograph of their face. The importance of the subject lies in the fact that many people are unfairly judged as criminals based on stereotypes such as race. In this study, we wished to eliminate race and see if any purely facial characteristics are stereotypically defined as criminal or if a person’s initial judgment is an accurate predictor of someone’s character. Extensive research has been dedicated to finding if people have facial features that portray some characteristic about them and this study will focus on criminality. Through the use of a face modulating program, neutral faced photographs were shown to participants with a question that asked if the person in the photograph is a criminal or not. The data gathered will be beneficial in either identifying facial features that are associated with criminals or that show the interesting phenomena of gut instinct