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Model based visualization of vibrations in mechanical systemsJitpraphai, Thanat 11 June 1997 (has links)
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
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Conceptual modeling architecture and implementation of object-oriented simulation for automated guided vehicle (AGV) systemsWang, I-Chien 09 June 1995 (has links)
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
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Support for model coupling : an interface-based approach /Bulatewicz, Thomas Francis, January 2006 (has links)
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.
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Complementary orthogonal stacked metal oxide semiconductor a novel nanoscale complementary metal oxide semiconductor architecture /Al-Ahmadi, Ahmad Aziz. January 2006 (has links)
Thesis (Ph.D.)--Ohio University, June, 2006. / Title from PDF t.p. Includes bibliographical references (p. [69]-[78])
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The Impact of Computer Simulation on the Development of the Inquiry Skills of High School Students in PhysicsIbrahim Mustafa, Mohamed 24 February 2011 (has links)
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.
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Object oriented simulation tools for discrete-continuous, stochastic-deterministic simulation modelsFisher, Joseph A., 1961- 24 August 1992 (has links)
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
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Managing urban development : a simulation approach for coping with change at a municipal parking structureWhite, Stephen James 22 April 1991 (has links)
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
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The Impact of Computer Simulation on the Development of the Inquiry Skills of High School Students in PhysicsIbrahim Mustafa, Mohamed 24 February 2011 (has links)
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.
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Structure of gas-liquid interface and hydrophobic interface for urea aqueous solution: a computer simulation studyYu, Meng 15 May 2009 (has links)
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.
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Ecophsiology of Growth in the Pacific White Shrimp (Litopenaeus vannamei)Walker, Scott J. 2009 May 1900 (has links)
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.
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