Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 129-135).

Poly(dimethylsiloxane) (PDMS) fluids containing magnetite nanoparticles stabilized with carboxylic acid-functionalized PDMS were prepared. PDMS-magnetite complexes were characterized using transmission electron microscopy, elemental analysis, and vibrating sample magnetometry. PDMS-magnetite complexes containing up to 67 wt% magnetite with magnetizations of ~52 emu gram-1 were prepared. The magnetite particles were 7.4 ± 1.7 nm in diameter. Calculations suggested that the complexes prepared using mercaptosuccinic acid-functionalized PDMS (PDMS-6COOH) complexes contained unbound acid groups whereas the mercaptoacetic acid-functionalized PDMS (PDMS-3COOH) complexes did not. Calculations showed that the PDMS-3COOH and PDMS-6COOH covered the same surface area on magnetite. Calculations were supported by molecular models and FTIR analyses. The complexes were dispersed into PDMS carrier fluids by ultrasonication, resulting in magnetic PDMS fluids with potential biomedical applications. Magnetite particles (100 nm to 1 mm in diameter) were prepared by crystallization from goethite/glycol/water solutions under pressure. Two methods for particle growth were investigated in which the crystallization medium was varied by adjusting the amount of water or by adding itaconic acid. Particle surfaces were analyzed by x-ray photoelectron spectroscopy (XPS). Particles with clean surfaces were coated with carboxylic acid-functionalized poly(e-caprolactone) stabilizers. Adding itaconic acid to the reactions afforded particles ~100 nm in diameter. The magnetite particles displayed magnetic hysteresis. The particles were dispersed into vinyl ester resins by ultrasonication and it was demonstrated that the ~100 nm particles remained dispersed for three days without agitation. These dispersions have applications in magnetic induction heating for composite repair. Living polymerizations of hexamethylcyclotrisiloxane were terminated with dimethylchlorosilane, phenylmethylchlorosilane, or diisopropylchlorosilane (DIPCS). Platinum-catalyzed hydrosilation of the hydrosilane-terminated PDMS with allyloxyethanol afforded a systematic series of hydroxyalkyl-terminated PDMS. The reactions were successful except for the hydrosilation of the sterically-hindered DIPCS-functionalized PDMS where no reaction was observed. Hydroxyalkyl-terminated PDMS oligomers were successful in initiating the stannous octoate-catalyzed copolymerization of e-caprolactone, which afforded PDMS-b-PCL diblock copolymers of controlled composition. / Ph. D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Electrical Engineering, 1965 / "September 1965." / Includes bibliographical references (leaf 65). / by Eduardo Jose Barragan Schenone. / S.B. / S.B. Massachusetts Institute of Technology, Department of Electrical Engineering

Lau Yiu Kee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 142-146). / Abstracts in English and Chinese. / LIST OF TABLES --- p.viii / LIST OF FIGURES --- p.x / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Railway Vehicle Suspension --- p.2 / Chapter 1.3 --- Semi-Active Magnetorheological Fluid Damper --- p.3 / Chapter 1.4 --- Research Objectives --- p.4 / Chapter 1.5 --- Thesis Outline --- p.5 / Chapter 2. --- BACKGROUND --- p.7 / Chapter 2.1 --- MR Fluids --- p.7 / Chapter 2.1.1 --- Composition of MR fluids --- p.7 / Chapter 2.1.2 --- Properties and characteristics of MR fluids --- p.8 / Chapter 2.1.3 --- Literature review --- p.13 / Chapter 2.2 --- MR Devices --- p.13 / Chapter 2.2.1 --- Advantages of MR devices --- p.13 / Chapter 2.2.2 --- Common device geometries --- p.14 / Chapter 2.2.3 --- MR fluid based applications --- p.15 / Chapter 2.2.4 --- Literature review --- p.19 / Chapter 2.3 --- Overview of Railway Vehicles --- p.21 / Chapter 2.3.1 --- "Passive, active and semi-active suspensions" --- p.21 / Chapter 2.3.2 --- Basic railway vehicle structure --- p.23 / Chapter 2.3.3 --- Literature review --- p.25 / Chapter 2.4 --- Railway Vehicle Suspension Systems --- p.25 / Chapter 2.4.1 --- Primary vertical suspension --- p.25 / Chapter 2.4.2 --- Secondary vertical suspension --- p.27 / Chapter 2.4.3 --- Secondary lateral suspension --- p.27 / Chapter 2.4.4 --- Yaw suspension --- p.28 / Chapter 3. --- DESIGN CONSIDERATIONS FOR MR DAMPERS --- p.29 / Chapter 3.1 --- Overview of Existing MR Dampers --- p.29 / Chapter 3.1.1 --- Monotube MR fluid damper --- p.29 / Chapter 3.1.2 --- Double-ended MR damper --- p.31 / Chapter 3.1.3 --- Bellow type MR damper --- p.35 / Chapter 3.2 --- Optimal Design and Configuration of Magnetic Circuit --- p.35 / Chapter 3.2.1 --- Magnetic circuit and magnetic field orientation --- p.35 / Chapter 3.2.2 --- Physical dimension of MR damper --- p.38 / Chapter 3.2.3 --- Connection polarity of electromagnetic circuit --- p.40 / Chapter 3.3 --- Basic Geometry Design Considerations --- p.43 / Chapter 3.3.1 --- Controllable force and dynamic range --- p.43 / Chapter 3.3.2 --- Geometry constraints --- p.45 / Chapter 3.3.3 --- Magnetic circuit design --- p.47 / Chapter 4. --- DEVELOPMENT AND FABRICATION OF MR DAMPERS --- p.51 / Chapter 4.1 --- Pneumatic Air Cylinder --- p.51 / Chapter 4.2 --- Fabrication Process of Double-Ended MR Dampers --- p.55 / Chapter 4.2.1 --- Modifications on the pneumatic air cylinder --- p.55 / Chapter 4.2.2 --- Manufacturing processes of the piston sleeve --- p.56 / Chapter 4.2.3 --- Modification processes of the original piston rod --- p.59 / Chapter 4.2.4 --- Modification of the piston staging area --- p.60 / Chapter 4.2.5 --- Copper wire wrapping and damper assembling --- p.63 / Chapter 5. --- EXPERIMENTAL SETUP AND RESULTS --- p.66 / Chapter 5.1 --- Experimental Setup for the Double-Ended MR Damper --- p.66 / Chapter 5.1.1 --- Instron 8801 loading machine --- p.66 / Chapter 5.1.2 --- Experimental setup for testing the MR damper --- p.67 / Chapter 5.2 --- Force-Lag Phenomenon of MR Damper --- p.70 / Chapter 5.2.1 --- Force-lag phenomenon --- p.70 / Chapter 5.2.2 --- Reasons of the force-lag phenomenon --- p.73 / Chapter 5.2.3 --- Methods to eliminate the force-lag phenomenon --- p.76 / Chapter 5.2.4 --- Setup for hydraulic pump system --- p.77 / Chapter 5.2.5 --- Results and effects of the pressurized MR damper --- p.79 / Chapter 5.3 --- Experimental Results for Testing the MR Damper --- p.83 / Chapter 6. --- SIMULATION RESULTS OF SEMI-ACTIVE TRAIN SUSPENSION --- p.87 / Chapter 6.1 --- MR Damper Model --- p.87 / Chapter 6.2 --- Rail Vehicle Model --- p.92 / Chapter 6.3 --- Semi-Active Railway Suspension --- p.94 / Chapter 6.3.1 --- Lateral vibration on the train --- p.94 / Chapter 6.3.2 --- Semi-active control strategy --- p.95 / Chapter 6.4 --- Simulation Results --- p.98 / Chapter 6.4.1 --- Lower sway mode excitation --- p.99 / Chapter 6.4.2 --- Upper sway mode excitation --- p.105 / Chapter 6.4.3 --- Mixed sway mode excitation --- p.110 / Chapter 6.4.4 --- BR high speed assault course --- p.116 / Chapter 6.4.5 --- Discussions --- p.124 / Chapter 6.5 --- Effects of Vibration on Ride Comfort --- p.128 / Chapter 7. --- CONCLUSIONS --- p.134 / APPENDIX --- p.136 / BIBLIOGRAPHY --- p.142

It has been found that magneto-rheological (MR) devices can produce large controllable force/torque while consuming little power. In this research, an MR actuator that can function as a clutch or a brake is developed, in order to be applied to an assistive knee brace. The torque capability and dynamic characteristics of the MR actuator are evaluated. The relationship between the torque output and the applied coil current is given. The response time is also measured. Experimental results show that the MR actuator can provide enough torque for normal activities with sufficiently fast response. IP control and adaptive control are proposed to control the MR actuator. Experiments under these controls are carried out. With anti-windup strategies, both controls achieve good performances. However, adaptive control would be more promising since it can adapt to parameter variations and maintain good performance. An assistive knee brace that contains this MR actuator and a DC motor is developed. In order to study the performances of the knee brace before applied to human body, experiments are conducted for evaluation under a custom-built testing structure. IP-based state control and adaptive control are used to control both the MR actuator and DC motor. Experimental results demonstrate that the MR actuator and DC motor work well together to provide assistance as expected. Compared with that without MR actuator, the evaluation results show that the knee brace with MR actuator is more energy efficient during normal walking, while having better force controllability and safety. / by Chen, Jinzhou. / Adviser: Liao Wei Hsin. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 140-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

In this research, a novel magnetorheological (MR) fluids based multifunctional actuator for assistive knee braces is designed. To decrease the dimension of the actuation device while enhancing its perfonnances, a motor and MR fluids are integrated into a single device. With MR fluids, the actuator possesses multiple functions as motor, clutch, and brake while meeting the requirement of nonnal human motion as well. In this thesis, design details and operating principle of the actuator are illustrated, and possible configurations of the motor part and clutch/brake part are discussed. Finite element method is utilized to analyze the magnetic circuits, influence of pennanent magnet on MR fluids, and magnetic flux distribution. Different clutch/brake parts with various inner coils are compared and analyzed, followed by a design optimization to improve the output torque. Prototypes of the multifunctional actuator are fabricated and tested, and characteristics of each function are investigated. As the actuator has multiple functions, modeling is developed for different functions, and system identification is carried out to determine the parameters. Adaptive control is utilized to control the actuator for torque and speed tracking. A smart joint using such a multifunctional actuator is designed, and its prototype is fabricated and tested. Power consumptions of knee brace using the smart joint are investigated during normal walking cycle. The results show that the developed actuator and smart joint are promising to be used in assistive knee braces. / Guo, Hongtao. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 154-158). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Graduation date: 1998

Abstract In this paper, the optical properties of magnetic fluid thin films are studied. We present the experimental observation of optical linear birefringence and dichroism in magnetic fluid thin film induced by crossed magnetic field perpendicular to the direction of light propagation. According to our results, we ascertain that both the magnetic birefringence and dichroism are existed. Besides, we also find that the relations between magnetic field and magneto-optical effects changed with the applied magnetic field intensity.

Thesis (Ph.D.)--Cleveland State University, 2008. / Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 121-126). Available online via the OhioLINK ETD Center. Also available in print.

Please read he abstract in the section 00front of this document / Dissertation (M Eng (Chemical Engineering))--University of Pretoria, 2007. / Chemical Engineering / unrestricted