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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Dynamic properties of ferrofluids

Duan, Xiaodong 01 October 2000 (has links)
No description available.
2

Self-powered, self-sensing magnetorheological dampers. / CUHK electronic theses & dissertations collection

January 2012 (has links)
磁流變阻尼器可用於各種動態系統的半主動振動控制,非常有前景。在當前的磁流變阻尼器系統中,需要使用外加并分離的電源和動態傳感器。本論文提出并探索了自供能自傳感磁流變阻尼器。它將能源採集、動態傳感和磁流變阻尼三種技術集成到同一器件中,具有內置的發電機制,和速度/位移傳感能力。此多功能的集成可以對當前的磁流變阻尼器系統帶來眾多的益處,如更節能、更高的可靠性、尺寸及重量的減少、較低的成本、以及更少的維護需求。該研究成果可以促進各種動態系統,如懸架系統和義肢的發展。 / 在論文中,作者對自供能自傳感磁流變阻尼器的概念、原理、設計方法、設計難點及解決方案進行了探討,設計製作了兩件原型,並對原型進行了性能測試。作者提出并探索了幾種可與磁流變阻尼器集成的發電機制,和動態傳感的方法。對發電、動態傳感和阻尼力三種性能,進行了建模、理論分析、以及實驗驗證。作者提出并驗證了自供能自傳感磁流變阻尼器的數學模型,該模型考慮了單獨的功能以及多功能間的相互作用。本論文對自供能磁流變阻尼器系統進行了探討分析,包括能源產生與磁流變阻尼的相互作用、自供能判據、工作範圍和設計指引。還提出并探索了一個自供能控制器,以及一種複合的磁場隔離方法。 / Magnetorheological (MR) dampers are promising for semi-active vibration control of various dynamic systems. In the current MR damper system, separate power supply and dynamic sensor are required. This research is aimed to propose and investigate self-powered, self-sensing (SPSS) MR dampers, which integrate energy harvesting, sensing and MR damping technologies into one device. SPSS MR damper has self-contained power generation and velocity/displacement sensing capabilities. This multifunctional integration will bring great benefits such as energy saving, higher reliability, size and weight reduction, lower cost, and less maintenance for the use of MR damper systems. It will advance the technology of various dynamic systems such as suspensions and prostheses. / Concepts, principles, design methodology, key issues and solutions of SPSS MR dampers are studied. Two prototypes of the SPSS MR dampers are designed, fabricated, and tested. Several integrated power generation and sensing methods for MR dampers are proposed and investigated. Modeling, theoretical analyses, and experimental studies on power generation ability, sensing capability and damping force performances are conducted. Models of SPSS MR dampers considering individual functions and interactions are developed and validated experimentally. Systematic studies on the self-powered MR damper system are performed, including interaction between the power generation and MR damping, self-powered criterion, working range and design guidelines. Moreover, a self-powered controller and combined magnetic-field isolation method are proposed and investigated. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Chao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 163-172). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / ABSTRACT --- p.i / 摘要 --- p.iii / TABLE OF CONTENTS --- p.vii / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xvii / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background and Motivation --- p.2 / Chapter 1.1.1 --- MR fluids --- p.2 / Chapter 1.1.2 --- MR dampers --- p.3 / Chapter 1.1.3 --- Previous research on functional integration of MR dampers --- p.7 / Chapter 1.2 --- Research Objective --- p.10 / Chapter 1.3 --- Thesis Organization --- p.12 / Chapter 2 --- DESIGN OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.13 / Chapter 2.1 --- Concept and Key Issues of Multifunctional Integration --- p.14 / Chapter 2.2 --- Configurations of Different Methods of Multiple Functions --- p.17 / Chapter 2.3 --- Principles of SPSS MR Dampers --- p.18 / Chapter 2.3.1 --- Structure and operation principle of the first prototype --- p.18 / Chapter 2.3.2 --- Structure and operation principle of the second prototype --- p.21 / Chapter 2.3.3 --- Energy flow of SPSS MR damper --- p.25 / Chapter 2.4 --- Materials Used in Design --- p.27 / Chapter 2.5 --- Fabrication of Prototypes --- p.32 / Chapter 2.6 --- Experimental Setup --- p.35 / Chapter 2.7 --- Chapter Summary --- p.37 / Chapter 3 --- POWER GENERATION OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.39 / Chapter 3.1 --- Introduction to Electromagnetic Energy Harvesting --- p.40 / Chapter 3.2 --- Finite Element Method --- p.42 / Chapter 3.3 --- Slotted Power Generation Method --- p.44 / Chapter 3.3.1 --- Modeling and analysis of slotted power generation --- p.44 / Chapter 3.3.2 --- Experimental results of slotted power generation --- p.52 / Chapter 3.4 --- Slotless Power Generation Method --- p.56 / Chapter 3.4.1 --- Design considerations --- p.56 / Chapter 3.4.2 --- Modeling and analysis of slotless power generation --- p.57 / Chapter 3.4.3 --- Experimental results of slotless power generation --- p.62 / Chapter 3.5 --- Frequency Multiplication Effect of Generated Voltage --- p.65 / Chapter 3.6 --- Chapter Summary --- p.67 / Chapter 4 --- SENSING OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.69 / Chapter 4.1 --- Introduction to Self-sensing Ability --- p.70 / Chapter 4.1.1 --- Self-sensing for vibration control --- p.70 / Chapter 4.1.2 --- Self-sensing of SPSS MR damper --- p.71 / Chapter 4.2 --- Moving-spacer Velocity Sensing Method --- p.73 / Chapter 4.3 --- Velocity-extraction Method from Slotted Power Generator --- p.80 / Chapter 4.4 --- Velocity-extraction Method from Slotless Power Generator --- p.86 / Chapter 4.5 --- Chapter Summary --- p.90 / Chapter 5 --- DAMPING FORCE OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.93 / Chapter 5.1 --- Design of MR Damping Part --- p.94 / Chapter 5.2 --- Testing Results of MR Damping Force of the First Prototype --- p.97 / Chapter 5.3 --- Testing Results of Damping Force of the Improved Prototype --- p.101 / Chapter 5.4 --- Damping Force Modeling and Identification --- p.105 / Chapter 5.5 --- Chapter Summary --- p.110 / Chapter 6 --- INTERACTION ANALYSIS --- p.111 / Chapter 6.1 --- Modeling Summary and Magnetic Field Interactions of SPSS MRD --- p.112 / Chapter 6.1.1 --- Modeling summary of SPSS MR dampers --- p.112 / Chapter 6.1.2 --- Magnetic field interactions --- p.114 / Chapter 6.2 --- Analysis of a Versatile Self-powered MR Damper System --- p.122 / Chapter 6.3 --- Application to Vehicle Suspension Systems --- p.130 / Chapter 6.3.1 --- Modeling of suspension system --- p.131 / Chapter 6.3.2 --- Working range and vibration control efficiency under on-off controller --- p.133 / Chapter 6.4 --- Design Guidelines of Self-powered Working Range --- p.141 / Chapter 6.5 --- A Proposed Self-powered Controller --- p.146 / Chapter 6.6 --- Chapter Summary --- p.153 / Chapter 7 --- CONCLUSION AND FUTURE WORK --- p.155 / Chapter 7.1 --- Conclusion --- p.155 / Chapter 7.2 --- Future Work --- p.160 / Chapter 8 --- BIBLIOGRAPHY --- p.163 / Chapter 9 --- APPENDIX --- p.173 / Chapter A. --- MR Fluid Datasheet --- p.173 / Chapter B. --- Sectional Views of Prototypes --- p.175
3

Hydrodynamic effects of particle chaining in liquid-solid magnetofluidized beds : theory, experiment, and simulation

Cruz-Fierro, Carlos Francisco 27 April 2005 (has links)
In a fluidized bed of magnetically susceptible particles, the presence of a magnetic field induce the formation of particle chains due to interparticle magnetic forces. The resulting effect is a change in the overall spatial distribution of the particles, transitioning from a random, isotropic distribution to an ordered, anisotropic distribution. For a magnetic field with the same direction as the superficial fluid velocity, the resulting structures offer less resistance to flow, resulting in a decrease of the effective drag coefficient. Thus the bed is less expanded and have lower voidage in the presence of the magnetic field, at a given fluid superficial velocity. The effect of particle chaining in the particle drag in a liquid-solid fluidized bed is studied. Experimental data is collected on voidage and pressure drop for particle Reynolds number between 75 and 190, and for particle chain separation force to buoyant weight ratio between 0 and 0.58. A two-parameter equation for the change in drag coefficient with respect to the hydrodynamic and magnetic operating conditions in the bed is obtained. It provides very good agreement with the experimental data. A proprietary 3-D simulation code implementing a Computational Fluid Dynamics-Discrete Particle Method is developed and tested under the same conditions as the experiments performed. Without the use of any correction in the drag coefficient, the simulation code overestimates the bed expansion by as much as 70%. This error is reduced to or below 10% when the drag coefficient is corrected using the equation here obtained. / Graduation date: 2005
4

The prediction of voidage distribution in a non-uniform magnetically assisted fluidized bed : theory and experiment

Sornchamni, Thana 22 November 2000 (has links)
Previous studies in Magnetically Stabilized Fluidized Bed (MSFB) are well known for conventional two-phase, gas-solid or liquid-solid fluidization. Many researchers have investigated the fluid dynamic behavior of the MSFB, however, all of these studies are based on a uniform magnetic field that is constant throughout the bed column. Currently, there are no references in the open literature indicating either fundamental or applied research with a magnetically fluidized bed where a non-uniform magnetic field is used in a two-phase liquid-solid fluidization. In this study, the fluid dynamic behavior of a Magnetically Assisted Fluidized Bed (MAFB) in a non-uniform magnetic field is experimentally observed. In the MAFB, a magnetic force, F[sub m] , is created which acts on the ferromagnetic particles (20% ferrite) by varying the magnetic field intensity from the top to the bottom of the fluidization column. However, the field gradient is kept constant throughout the bed. Because of the differences in the magnetic field intensity at any location in the bed, the particle holdup, or inversely the bed voidage, has to change to accommodate the equilibrium of forces acting on the particles (drag force, gravitational force, buoyancy force, and magnetic force). In the laboratory experiments, performed magnetic field gradient, [see PDf for equation] Alm/m, -18,289 Alm/m, -20,543 Alm/m and -33,798 A/m/m) and fluid flow rate (U[sub 0] =0.0153 m/s, 0.0176 m/s, 0.0199 m/s and 0.0222 m/s) are varied. These experiments show that the increase in the magnetic field gradient and the magnetic field intensity results in the decrease in the height of the bed, and therefore, in the decrease of the bed voidage. The dynamic pressure drop, [delta]P[sub f][sub(d)], is also experimentally measured, then converted to a corresponding voidage. The relationship between the dynamic pressure drop and the bed voidage is given by the following equation:[see PDF for equation] The fluid dynamic behavior of the MAFB is described by the equation of motion and the equation of continuity for both liquid and solid phases. A mathematical model is developed and used to evaluate the voidage distribution in the MAFB. The resulting expression for the voidage distribution in the MAFB is given as [see PDF for equation]. Experimentally obtained bed voidage data in both, laboratory experiments (1g) and on board of the NASA KC-135 plane (0g) fit very well the above equation which does not have any adjustable parameter. / Graduation date: 2001
5

Encapsulation of magnetosomes in lipid vesicles

Liu, Shuk Yi 01 January 2004 (has links)
No description available.
6

Isoperibol calorimetry and its application in organic molecules and binary systems

Klimov, Mikhail 01 January 1999 (has links)
No description available.
7

Locomotion of magnetic objects in fluids /

Bhat, Shubham K. Kurzweg, Timothy P. January 2008 (has links)
Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract. Includes bibliographical references (leaves 138-149).
8

Analysis of forces acting on super paramagnetic beads in fluid medium in the presence of non uniform magnetic beads

Veeramachaneni, Usha K. January 2009 (has links)
Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xiii, 96 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).
9

Direct numerical simulation of ferrofluid turbulence in magnetic fields /

Schumacher, Kristopher Ray, January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 168-171).
10

A feasibility study of magneto-rheological fluids for micro devices.

January 1999 (has links)
Ho Chi-hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 50-51). / Abstracts in English and Chinese. / Chapter CHAPTER ONE: --- INTRODUCTION --- p.1 / Introduction --- p.1 / Motivation of the Problem --- p.1 / Organization of this Thesis --- p.2 / Chapter CHAPTER TWO: --- LITERATURE SURVEY --- p.3 / Introduction --- p.3 / Electrorheological Fluid --- p.3 / Magnetorheological Fluid --- p.4 / Ferrofluid --- p.4 / "Comparison Amount ER, MR and Ferrofluid" --- p.5 / Chapter CHAPTER THREE: --- THEORETICAL ANALYSIS OF MR FLUIDS FOR MICRO DEVICES --- p.8 / Introduction --- p.8 / Minimal Volume --- p.8 / Magnetic Field Requirement --- p.10 / Particle Size --- p.14 / Chapter CHAPTER FOUR: --- PROCESSING TECHNOLOGY --- p.15 / Introduction --- p.15 / Processing Technology --- p.15 / Chapter CHAPTER FIVE: --- MR FLUID PILLARS --- p.18 / Introduction --- p.18 / Description of Experimental Setup --- p.18 / Finite element Analysis of the Experiment --- p.23 / Alignment Theory of MR Fluid Pillar --- p.29 / Discussion of Fluid Surface Tension --- p.36 / Chapter CHAPTER SIX: --- APPLICATIONS --- p.39 / Introduction --- p.39 / MR Fluid Actuator --- p.39 / Micro Brake --- p.45 / Micro Brake --- p.46 / Micro Clutches --- p.46 / Damper for Micro-Robot System --- p.46 / Chapter CHAPTER SEVEN: --- CONCLUSION --- p.48 / APPENDIX --- p.49 / BIBLIOGRAPHY --- p.50

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