To visualize vibrations in mechanical systems, e.g., machine tools, their movements are measured by means of suitable sensors. The signals from these sensors are processed and displayed as animated pictures on a computer screen. Accelerometers have been chosen as the most suitable sensors for this purpose. Their main advantages include small size, wide sensitivity range and frequency bandwidth. In addition, accelerometers measure signals with reference to the Earth, so they do not require stable fixtures such as used with cameras or lasers. The visualization methodology involves nine accelerometers attached to a mechanical component, e.g., a dynamometer's platform. Vibration signals were acquired using a data acquisition (DAQ) system which is controlled by a LabVIEW��-based program. These signals are processed to suppress errors and convert acceleration into generalized coordinate that describes motion of the visualized component as a rigid plate's movement in 3-D space. The animation is accomplished by displaying a time series of pictures representing instantaneous position of the plate. The animation program employs homogenous coordinate transformation to draw 3-D 'wireframe' pictures. Since various errors distort the measured signals, the animated movement may be inaccurate. The knowledge of a mathematical model of the system whose vibrations are animated allows detection and suppression of distortions. For this purpose, the signals measured from the actual dynamic system are compared with the signals simulated by the system's model subjected to the same excitation as the actual system. Discrepancies between the actual and simulated signals are detected. They are analyzed to identify possible sources and forms of distorting signals. As the next step, the measured (actual) signals are corrected by removing estimated distortions. A methodology and software package capable of performing all functions necessary to implement the visualization of vibration have been developed in this research using LabVIEW�� programming environment. As compared with commercial software for experimental modal analysis, the most distinctive feature of the developed package is improved accuracy achieved by applying concepts utilized in control theory, such as modeling of multi-input-multi-output (MIMO) systems and on-line system identification for the model development and correction of signals. / Graduation date: 1998

Traditional simulation languages and simulators do not fully support the need to design, modify, and extend simulation models of manufacturing systems, especially, material handling systems. Since AGV systems, one type of automated material handling systems, require complicated control logic, flexible job routings, and frequent layout modifications and extensions to correspond to production requirements, the time consumption and efforts to achieve the above tasks in traditional paradigms are significant. However, such difficulties can be overcome by the use of object-oriented simulation. This research develops an object-oriented modeling architecture for the simulation of AGV (automated guided vehicle) systems by extending Beaumariage's object-oriented modeling environment (1990) which is originally designed for the simulation of job shop type manufacturing systems. For this extension, several classes required to comprise an AGV system are created into the original environment which include AGV, limited size queue, control point, track segment, machine cell, AGV system control classes, and so on. This architecture provides a flexible environment that enables the modeling of traditional and tandem AGV system layouts. A best-first search approach, one artificial intelligence search algorithm, is employed to direct AGVs to determine the shortest path from all possible travel paths. The computerized modeling system with this conceptual architecture is easy to use, especially compared with traditional simulation tools. In addition, the extended object-oriented architecture used for the simulation of AGV systems is program independent and may be implemented in any object-oriented language. The prototype system implemented as a portion of this research is performed in Smalltalk/V. Two case examples are presented for verification and validation. / Graduation date: 1996

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 191-198). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph.D.)--Ohio University, June, 2006. / Title from PDF t.p. Includes bibliographical references (p. [69]-[78])

The purpose of the study was to compare the effectiveness of visualization of natural phenomena via computer simulation and manipulations of concrete objects, in a physics laboratory, on the development of students’ inquiry skills in mechanics. A quasi-experimental method that employed the 2 Learning Tools x 2 Time of learning split-plot factorial design was applied in the study. The sample consisted of 54 Grade 11 students from two physics classes of the university preparation section in the Ottawa-Catholic School Board. One class was assigned to interactive computer simulations (treatment) and the other to concrete objects in physics laboratory (control) as learning tools. Both tools were embedded in the general framework of the guided-inquiry cycle approach. The results showed that the interaction effect of the Learning Tools x Time of learning was not statistically significant. However, the results also showed a significant effect on the development of students’ inquiry skills (indicated by the pre- and post-inquiry skills test) regardless of the type of learning tool they had used. The findings suggested that these two strategies are effective in developing students’ inquiry skills in mechanics.

In this thesis an introduction to simulation and object oriented programming discusses the need for the creation of several classes which directly support object oriented simulation. The author places no restrictions on the type of simulations that can be conducted and simulation practitioners will find that the classes provided lay the groundwork for a robust object oriented simulation language. In order to appreciate the development of the simulation classes, three examples from the literature demonstrate their use in continuous deterministic and discrete stochastic simulations. In addition to the creation of several basic simulation constructs, two advanced simulation tools were developed. Inter-object communication and intelligent simulation capabilities will increase the power and flexibility available to simulation modeler's. Programmers, scientists, and engineers will appreciate the object oriented simulation engine and generic simulation objects that were created. / Graduation date: 1993

Public construction projects are frequently presented as occurring in complex social, political and economic settings described as being uncertain. In public administration, this uncertainty is cited as a cause for shifting from the so called "rational-comprehensive" model of policy and decision making toward an "incremental" or "mixed-scanning" approach. None of these models provides a panacea for dealing with the influences of the diverse and dynamic social and political attitudes, ethics and values that are inherent in urban settings. Where such uncertainty becomes unmanageable scientific experts are called upon to translate the problem into technical or economic language that lends itself to consideration by traditional management science analysis. This thesis describes one such translation of an urban transportation development project in the context of the political and philosophical exigencies which required its undertaking. A computer simulation approach to modelling the operation of a two-story underground parking structure, named the Capitol Mall Parking Structure, is described as well as the model's results and sensitivity in coping with various uncertainties posed by the project's decision makers. / Graduation date: 1992

The purpose of the study was to compare the effectiveness of visualization of natural phenomena via computer simulation and manipulations of concrete objects, in a physics laboratory, on the development of students’ inquiry skills in mechanics. A quasi-experimental method that employed the 2 Learning Tools x 2 Time of learning split-plot factorial design was applied in the study. The sample consisted of 54 Grade 11 students from two physics classes of the university preparation section in the Ottawa-Catholic School Board. One class was assigned to interactive computer simulations (treatment) and the other to concrete objects in physics laboratory (control) as learning tools. Both tools were embedded in the general framework of the guided-inquiry cycle approach. The results showed that the interaction effect of the Learning Tools x Time of learning was not statistically significant. However, the results also showed a significant effect on the development of students’ inquiry skills (indicated by the pre- and post-inquiry skills test) regardless of the type of learning tool they had used. The findings suggested that these two strategies are effective in developing students’ inquiry skills in mechanics.

Urea aqueous solution is ubiquitously used to denature protein. Regardless of its extensive use, the mechanism is still unclear and remains an active field of study. There have been two proposed mechanisms, the direct and indirect. The indirect mechanism, which attributes the ability of urea of changing water structure, is susceptible since many research works show that there is little effect of urea on water structure. The current study provided evidence for the indirect mechanism by demonstrating that the introduction of urea slightly changes the water structure in the hydrophobic interfacial areas. In the current study, the urea aqueous solution systems with either gas-liquid or hydrophobic interface are studied by MD simulations, and the structures of water near the interfacial areas are analyzed in terms of density, orientation and number of hydrogen bonds. For each kind of interface, systems with four different urea concentrations are included, ranging from 0M to 8M. The results show slight change of water structure by the urea solute on the hydrophobic interface in terms of the orientation and number of hydrogen bonds per water molecule.

Ecophysiological responses of Litopenaeus vannamei were evaluated as functions of 1) salinity and animal size, 2) temperature and the animal's nutritive state, and 3) dissolved-oxygen concentration and animal size. Growth rate, routine metabolic rate, limiting oxygen concentration for routine metabolism, and marginal metabolic scope were determined for L. vannamei maintained and tested at salinities of 2, 10, and 28 ppt, all at 28 C. Routine metabolic rate (RMR) was not demonstrably dependent on salinity but decreased with increasing shrimp weight. Limiting oxygen concentration for routine metabolism (LOCr) was independent of shrimp weight up to 9 g; but, for larger shrimp, decreased with increasing weight. Marginal metabolic scope (MMS = RMR/LOCr) also decreased with increasing shrimp weight and was independent of salinity for shrimp weighing up to 9 g; but, like LOCr, MMS was dependent on salinity for larger shrimp. Growth rate was significantly less at 2 ppt than at 10 or 28 ppt, which gave similar growth rates. The effects of four temperatures (20, 24, 28, and 32 C) on growth, RMR, LOCr, and MMS were examined for fed and starved L. vannamei. Routine metabolic rate increased with increased temperature both for fed and starved shrimp. Marginal metabolic scope and growth appeared to be positively related and, at 20 C, seemed to induce a state of metabolic torpor. Data from the study of chronic effects of hypoxia (~2 mg O2 L-1) vs. normoxia (> 5 mg O2 L-1) on ecophysiological responses indicated that although low-DO environments can depress RMR and growth in L. vannamei, animals grown under hypoxic and normoxic conditions did not differ in their metabolic responses upon acute exposure to hypoxia, providing no evidence of acclimation to hypoxia in L. vannamei. Data from the above experiments were used to parameterize Ecophys.Shrimp, a computer simulation model of shrimp growth in time-varying environmental regimes. One unified model was able to simulate all my experiments; and, with only minimal adjustment of the model parameter MMSO, it also adequately simulated studies taken from the literature. Thus, Ecophys.Shrimp seems capable of realistically representing the ecophysiological dynamics of shrimp metabolism and growth in various culture systems.