Inertia Effect of the Fluid Particles on the Lubricant Flow in a Dynamic Thrust Bearings
Closed form equations are derived from the fundamental principles for the evaluation of volume flow rate of lubricant in between the pads of a thrust bearing accounting for the centrifugal inertia effect. Two types of configuration i.e. parallel disk and nonparallel disk configurations are considered. The theoretical analysis is presented.
Design, modeling, fabrication, and testing of a multistage micro gas compressor with piezoelectric unimorph diaphragm and passive microvalves for microcooling applications
This dissertation investigates the development of a multistage micro gas compressor utilizing multiple pump stages cascaded in series to increase the pressure rise with passive microvalves and piezoelectric unimorph diaphragms. This research was conducted through modeling, simulation, design, and fabrication of the microcompressor . and its components. A single-stage and a two-stage microcompressor were developed to demonstrate and compare the performance and effectiveness of using a cascaded multistage design. Steady fluid flow through static microvalves structure was studied to gain insight on its gas flow dynamics and characteristics. Transient analysis combined with the structure’s interaction was investigated with an analytical model and FEM model. The static analysis and transient analysis enabled lumped model parameter extraction for modeling and simulations. The transient FEM solution of the microvalve fluid-structure interaction (FSI) allows for extraction of the damping ratio for the lumped model. The microvalves were fabricated with MEMS microfabrication methods and integrated into a machined microcompressor housing. Study from the simulation of the microvalve fluidstructure dynamics in Simulink showed the frequency of the micro valves, at which frequency the microvalve is more prone to leakage. Simulation indicated that the reverse leakage from the sealing of the microvalve can have.a significant impact on the pressure rise performance of the compressor. A model of the singleand the two-stage microcompressor were developed with Simulink to observe the dynamics and performance of the multistage microcompressor. The simulation shows the dead volume between the two chambers to decrease in the overall pressure rise of the multistage microcompressor. Operating scenarios with different frequency and in phase and out of phase actuation between stages were simulated to understand the dynamics and performance of the multistage design. The fabricated singleand two-stage microcompressor produced a maximum pressure rise of 10 kPa and 18 kPa, respectively, and a maximum flow rate of 32 seem for both. To obtain these maximum pressure rises, the microcompressors were operated at high frequency at the resonance of the piezoelectric diaphragm. This dissertation investigated the feasibility and operation of a multistage gas microcompressor with passive microvalves, allowing the exploration of its miniaturization. APPROVAL FOR SCHOLARLY DISSEMINATION The author grants to the Prescott Memorial Library of Louisiana Tech University the right to reproduce, by appropriate methods, upon request, any or all portions of this Dissertation. It is understood that “proper request” consists of the agreement, on the part of the requesting party, that said reproduction is for his personal use and that subsequent reproduction will not occur without written approval of the author of this Dissertation. Further, any portions of the Dissertation used in books, papers, and other works must be appropriately referenced to this Dissertation. Finally, the author of this Dissertation reserves the right to publish freely, in the literature, at any time, any or all portions of this Dissertation.
Bodies of Evidence: Burial, Memory and the Recovery of Missing Persons in Cyprus
List of Figures and Maps Acknowledgements Chapter 1. Heirs of Antigone: Disappearances and Political Memory Chapter 2. Suppressed Experiences Chapter 3. Testimonies of Fragmentation, Recollections of Unity Chapter 4. The Missing as a Set of Representations Chapter 5. The Martyrdom of the Missing Chapter 6. L'image Juste, or Juste une Image? Chapter 7. Painting Absences, Describing Losses Chapter 8. Antigone's Doubt, Creon's Dilemma Chapter 9. Power, Complicity, and Public Secrecy Bibliography Appendices Index