In observations of steady-state nucleate boiling, fluctuations in the temperature and heat flux might initially appear to be completely random. However, it was shown that, for a vertically mounted platinum wire in liquid nitrogen, the fluctuations about the steady-state exhibit an average counterclockwise circulation when the heat flux is plotted versus the superheat temperature. An area associated with the average circulation was proposed as a numerical measure of stability for steady-state nucleate boiling. The mechanisms for the generation of these fluctuations are thought to be the feedback of the bubbles rising past the wire and the differential heating and cooling that this engenders. Data similar to the data on the vertical wire have been obtained using the same wire mounted horizontally. Although the counterclockwise circulation mentioned above is still seen, the measure of stability as proposed earlier, is less useful for prediction of the transition to film boiling. This reduced sensitivity can be attributed to the fact that the possibility of feedback through the rising bubbles has been eliminated.

Novel seasonal hidden Markov models (SHMMs) for stochastic time series with periodically varying characteristics are developed. Nonlinear interactions among SHMM parameters prevent the use of the forward-backward algorithms which are usually used to fit hidden Markov models to a data sequence. Instead, Powell's direction set method for optimizing a function is repeatedly applied to adjust SHMM parameters to fit a data sequence. SHMMs are applied to a set of meteorological data consisting of 9 years of daily rain gauge readings from four sites. The fitted models capture both the annual patterns and the short term persistence of rainfall patterns across the four sites.

Abstract not available

Bibliography: leaves [238]-244.

Researchers in the Forms/3 group have previously developed the WYSIWYT methodology, exploring a way of systematically testing spreadsheet languages. The previous work presented the WYSIWYT methodology for individual spreadsheet cells, and later partially extended it to large grids in which some cells share the same formula. The Forms/3 spreadsheet language supports not only operations of individual cells but also some advanced programming features such as homogeneous grids, recursive programs, and user-defined abstract data types. Therefore, it is important for the testing methodology to support even these more powerful features of the language, not just the "easy parts". In this document, we present extensions to the WYSIWYT methodology for these advanced features. We optimized the visual aspects of testing spreadsheet grids and collected experimental information about scalability. We also developed two possible ways the WYSIWYT methodology could be extended to accommodate recursion in terms of their testing theoretic aspects, implementation strategies, algorithms and time complexities. Since the ultimate goal is to help the people using these languages, we also conducted an empirical study and used its results to inform our choice as to which of these two approaches to adopt. Finally, we developed an approach of testing user-defined abstract data types; here we present design, implementation issues, algorithms and time complexities. / Graduation date: 2002

A project funded by the Southern California Edison (SCE) Company, Research Center of Irwindale, California, has supported the development of a performance and parameter prediction software program for use during the refurbishment of large synchronous machines, turbine generators, and synchronous condensers. The computer program was developed for SCE to allow user friendly input of a machine's physical parameters such as pole/field/winding/stator dimensions, type of steel, and other related information in order to calculate the machine's reactances, time constants, and performance curves. The program also allows some degree of design calculation to be performed in order to meet certain design criteria where appropriate. The theory behind the calculations upon which the electrical calculations are built is obtained primarily from literature published in the early 1950's. Since that time, however, machine design has progressed into ever larger generators, most often in the hundreds of Megawatt range with some units exceeding one thousand Megawatts. This size increase has established the practice of winding the stator coils into parallel circuits to maintain acceptable flux and generated voltage levels. These design practices justify a re-examination of the traditional methods used to calculate a machine's reactances and time constants. Accordingly, the use of parallel circuits in the stator winding and their effect on machine parameters has not, to this author's knowledge, been addressed in public literature. These issues are exam fled and modifications to the traditional formulas have been derived for the reactances along with the process of carrying out the calculations on a per pole basis. In addition, the calculation of the parameter and performance equations of a machine are suitable for implementation on a computer due to the length and often iterative calculation procedures. The procedures used to calculate the capability and saturation curves directly from the machine's physical dimensions are developed. During development of the program a forty megawatt generator was measured in order to test and debug the program. Results of this test case are presented and compared to test values obtained at the time of the generator's installation. / Graduation date: 1994

Following natural language instructions requires transforming language into situated conditional procedures; robustly following instructions, despite the director's natural mistakes and omissions, requires the pragmatic combination of language, action, and domain knowledge. This dissertation demonstrates a software agent that parses, models and executes human-written natural language instructions to accomplish complex navigation tasks. We compare the performance against people following the same instructions. By selectively removing various syntactic, semantic, and pragmatic abilities, this work empirically measures how often these abilities are necessary to correctly navigate along extended routes through unknown, large-scale environments to novel destinations. To study how route instructions are written and followed, this work presents a new corpus of 1520 free-form instructions from 30 directors for 252 routes in three virtual environments. 101 other people followed these instructions and rated them for quality, successfully reaching and identifying the destination on only approximately two-thirds of the trials. Our software agent, MARCO, followed the same instructions in the same environments with a success rate approaching human levels. Overall, instructions subjectively rated 4 or better of 6 comprise just over half of the corpus; MARCO performs at 88% of human performance on these instructions. MARCO's performance was a strong predictor of human performance and ratings of individual instructions. Ablation experiments demonstrate that implicit procedures are crucial for following verbal instructions using an approach integrating language, knowledge and action. Other experiments measure the performance impact of linguistic, execution, and spatial abilities in successfully following natural language route instructions.

No description available.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

No description available.