Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 112-118).

Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (April 26, 2007). Vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This research develops a procedure to determine the applied stresses in rails using the acoustoelastic effect of ultrasonic waves. Acoustoelasticity is defined as the stress dependency of ultrasonic wave speed or wave polarization. Analytical models are developed that predict the acoustoelastic effect for longitudinal waves, shear waves, Lamb waves, and Rayleigh waves. Using a programming tool, a numerical simulation of the models is generated to obtain the stress dependent curves of wave velocity and polarization of the various ultrasonic waves propagating in rail steel. A comparison of the sensitivity of the acoustoelastic effect is made to determine the feasibility of ultrasonic waves for further study. Rayleigh waves are found to be most sensitive to stress change. Rayleigh waves are generated using ultrasonic transducer and detected using a laser Doppler vibrometer (LDV). The LDV measures the in-plane and out-of-plane velocities. Polarization is defined as the ratio of in-plane and out-of-plane displacements. Initially, polarization is determined for the specimen in unstressed condition. Thereafter, the rail specimen is stressed in a compression testing machine, the experiment repeated, and the polarization determined. Thus, Rayleigh wave polarization is obtained as a function of applied stress. Finally, the change in polarization obtained experimentally is compared with the analytical model.

This research develops a procedure to determine the applied stresses in rails using the acoustoelastic effect of ultrasonic waves. Acoustoelasticity is defined as the stress dependency of ultrasonic wave speed or wave polarization. Analytical models are developed that predict the acoustoelastic effect for longitudinal waves, shear waves, Lamb waves, and Rayleigh waves. Using a programming tool, a numerical simulation of the models is generated to obtain the stress dependent curves of wave velocity and polarization of the various ultrasonic waves propagating in rail steel. A comparison of the sensitivity of the acoustoelastic effect is made to determine the feasibility of ultrasonic waves for further study. Rayleigh waves are found to be most sensitive to stress change. Rayleigh waves are generated using ultrasonic transducer and detected using a laser Doppler vibrometer (LDV). The LDV measures the in-plane and out-of-plane velocities. Polarization is defined as the ratio of in-plane and out-of-plane displacements. Initially, polarization is determined for the specimen in unstressed condition. Thereafter, the rail specimen is stressed in a compression testing machine, the experiment repeated, and the polarization determined. Thus, Rayleigh wave polarization is obtained as a function of applied stress. Finally, the change in polarization obtained experimentally is compared with the analytical model.

Modeling of changing pressure, temperature, and density profiles in a wellbore as a function of time is crucial for design and analysis of pressure-transient tests (particularly when data are gathered above perforations), real-time management of annular-pressure buildup (ABP) and identifying potential flow-assurance issues. Other applications of this modeling approach include improving design of production tubulars and artificial-lift systems and gathering pressure data for continuous reservoir management. This work presents a transient wellbore model coupled with a semianalytic temperature model for computing wellbore-fluid-temperature profile in flowing and shut-in wells. The accuracy of the analytic heat-transfer calculations improved with a variable-formation temperature model and a newly developed numerical-differentiation scheme. Surrounding formation temperature is updated in every timestep up to a user specified distance to account for changes in heat-transfer rate between the hotter wellbore fluid and the cooler formation. Matrix operations are not required for energy calculations because of the semianalytic formulation. This efficient coupling with the semianalytic heat-transfer model increased the computational speed significantly. Either an analytic or a numeric reservoir model can be coupled with the transient wellbore model for rapid computations of pressure, temperature, and velocity. The wellbore simulator is used for modeling a multirate test from a deep offshore well. Thermal distortion and its effects on pressure data is studied using the calibrated model, resulting in development of correlations for optimum gauge location in both oil and gas wells. Finally, predictive capabilities of the wellbore model are tested on multiple onshore wells experiencing annular-pressure buildup problems. Modeling results compare quite well with the field data and also with the state-of-the-art commercial wellbore simulator.

This thesis presents an experimental analysis of the effect of temperature and thermal cycles on the performance of PZT ceramics in fuel injector applications. Due to the increase in the implementation of piezoceramics in applications such as fuel injection technology, it is imperative to understand how temperature affects piezoceramic performance. In this project, the fundamental piezoelectric properties (d_33, ε_33^T, s_33^E) of bulk PZT samples and high electric-field properties of piezoelectric stack actuators were obtained with respect to temperature and thermal cycles. The results show that increasing temperature will increase the fundamental piezoelectric properties of bulk piezoceramics, capacitance of stack actuators, and the displacement of piezoactuators in the absence of external load. Raising the temperature while applying a constant preload will initially increase piezoactuator displacement, but decrease it at higher temperatures. Temperature had a negative effect on the hysteresis in the displacement-voltage. Additionally, thermal hysteresis decreased significantly in subsequent temperature cycles.

This thesis presents an experimental analysis of the effect of temperature and thermal cycles on the performance of PZT ceramics in fuel injector applications. Due to the increase in the implementation of piezoceramics in applications such as fuel injection technology, it is imperative to understand how temperature affects piezoceramic performance. In this project, the fundamental piezoelectric properties (d_33, ε_33^T, s_33^E) of bulk PZT samples and high electric-field properties of piezoelectric stack actuators were obtained with respect to temperature and thermal cycles. The results show that increasing temperature will increase the fundamental piezoelectric properties of bulk piezoceramics, capacitance of stack actuators, and the displacement of piezoactuators in the absence of external load. Raising the temperature while applying a constant preload will initially increase piezoactuator displacement, but decrease it at higher temperatures. Temperature had a negative effect on the hysteresis in the displacement-voltage. Additionally, thermal hysteresis decreased significantly in subsequent temperature cycles.

The project is a detail study of Energy Balance in cutting line station in Sandvik Mining and construction group. The aim of the project is reducing temperature and making a temperature balance inside the cutting line. During the recent years, many changes occur in production line. Existing cooling system cannot supply cutting area temperature below the desired level. Electrical Cables are melting due to high inside temperature. We attempted to study the old drawings and existing cooling system in cutting station to find out solutions to optimize and rebuild the old system. First part of study contains checking of preliminary air and water cooling system drawings. In the second part we looked at the operating cooling system by measuring different available working conditions such as inside temperature, air velocity and cooling water flow rate with different measuring equipment. The study integrate hot and cold stream (cooling air and water system) at different temperature level and in different times through production or non-production hours. Finally results and solutions can give valuable guidance for enterprises on how cooling systems should be expanded, what sizes should the new equipment have, where should the heat recovery exchangers be built, what new pipelines are needed, etc. To find more accurate results, we tried to do all measurements simultaneously, but due to difficult working condition it was not possible to have all input data at the same time. According to the primary data energy consumption during different times and Peak consumption amounts were calculated. Results consider the differences in cooling system effects inside the cutting line and the system which generates more cooling load and needed more improvements.  The summer and winter conditions are different inside the work area. The simultaneous assurance of ventilation, energy reduction and occupant health remains a design challenge. Working area is a unman area; therefore environmental impact are not considered in this research.

This study is an experimental investigation pertaining to the creep behavior of slender pultruded fiber-reinforced polymeric (FRP) columns subjected to sustained concentric axial loading at elevated service temperatures. Six creep tests were performed on columns having a slenderness ratio of 49 at different combinations of axial load and temperature for a duration of at least 1,000 hours. The axial loads used represented 33%, 67%, and 90% of the critical buckling load for the column selected. For each load level, one test was performed at 22.8℃ (73℉) and one test was performed at 65.5℃ (150℉) Knife-edge end supports were utilized to simulate pinned-pinned boundary conditions. Midheight lateral deflection and axial shortening were recorded incrementally for the duration of the testing. Following termination of the creep tests, the columns were allowed to recover and tested for buckling strength. A semi-empirical model for long-term behavior of concentrically loaded FRP columns at elevated service temperatures is proposed based on experimental results.