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

Abstract In this paper, an algorithm for accurately finding the position, orientation and dipole moment of a transmitting dipole antenna buried in rock is presented. The algorithm is based on simplified radiation equations that are shown to be valid within a region of space in the extreme near field surrounding the antenna called termed quasi-static region. Within this region, medium dependent propagation effects are negligible, allowing accurate, medium independent resolution of position, orientation and dipole moment. The magnetic field magnitude and direction values observed at a number of arbitrarily located points in space are used by the algorithm to generate a system of nonlinear equations. This system of equations is solved using a simultaneous multi-variable Newton-Raphson solver with line searches and backtracking providing a measure of global convergence. An additional method, based on an iterated random search, further improves the global convergence capability of the algorithm. If the dipole moment of the transmitting antenna is known, measurements from two observer points are sufficient to resolve the position and orientation of the dipole. If the dipole moment is unknown, three observer points are required to solve for the unknown position, orientation and dipole moment. The algorithm is able to find an exact solution using exact theoretical measurements, and a minimised least squares solution where measurements are subject to noise. The theory relating to the algorithm is discussed including distance-frequency relations for the quasistatic region of a number of common rock types. Probabilistic modelling, simulation and test results of the algorithm are also included.

The magnetic (B) field is ubiquitous throughout the Milky Way. Several fundamental questions about the B-field in the cool, star-forming interstellar medium (ISM) remain unanswered. In this dissertation, near-infrared (NIR) polarimetric observations are used to study the large-scale Galactic B-field in the cool ISM in a spiral arm and to determine the role of B-fields in the formation of Infrared Dark Clouds (IRDCs). NIR polarimetry of 31 star clusters, located in and around the Perseus spiral arm, were obtained to determine the orientation of the plane-of-sky B-field in the outer Galaxy, and whether the presence of a spiral arm influenced B-field properties. Cluster distances, which provide upper limits to the B-field probed by observations, were estimated by developing a maximum likelihood method to fit theoretical stellar isochrones to stars in cluster color-magnitude diagrams (CMDs). Using the distance estimates, the cluster locations relative to the Perseus arm were found. The cluster polarization percentages and orientations were compared between clusters foreground to the arm and clusters inside or behind the arm. The cluster polarization orientations are predominantly parallel to the Galactic plane. Clusters inside and behind the arm have larger polarization percentages, likely a result of more polarizing material along the line of sight. The cluster polarization data were also compared to optical, inner Galaxy NIR, and Planck submm polarimetry data, and showed agreement with all three data sets. The polarimetric properties of one IRDC, G28.23, were determined using deep NIR observations. The polarization orientations relative to the cloud major axis were found to change directions with distance from the cloud axis. The B-field strength was estimated to be 10 to 100uG. Despite these large inferred B-field strengths, the B-field was found not to be the dominant force in the formation of the IRDC, though the B-field morphology was influenced by the cloud. Using NIR observations, the B-field of 27 IRDCs were studied. The relative polarization orientations with respect to the cloud major axes were found. No preferential relative orientation was found, implying that the B-field did not greatly influence the formation of this sample of IRDCs.

Our understanding of the magnetic fields of stars is nearly monopolized by knowledge of our own sun. Very-long baseline radio interferometry (VLBI) provides a means of directly imaging the radio coronae of other stars at a high enough resolution to discern discrete features, something not possible with other observational methods. It also allows the highest positional accuracy of any observational method available. This thesis details the VLBI study of two nearby radio-loud stars in close binary systems. Both systems were observed at numerous epochs spaced over a range of several months with the global-scale radio interferometer array the VLBA-HSA. These observations were combined with archival data from the National Radioastronomy Observatory (NRAO) Archive. The resulting positions, as well as previously published positions, were used to calculate a least-squares solution for all the orbital and astrometric parameters of both systems. This made it possible to determine the position of the physical star with respect to the radio emission in each image. The images of both stars were found to conform to theoretical emission produced by a model dipolar magnetosphere with a filled or partially-filled coronal loop.

No description available.

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

Three types of magnetic memory elements with emphasis placed on low cost and batch fabrication are investigated. The type I element consists of a wired hole in a strip of Deltamax tape. The type II element uses a stack of magnetic tape instead of the Deltamax. The type III element consists of a pre-wired grid with magnetic material deposited around the grid to simulate a wired core. The results obtained from these investigations showed conclusively that the type I element, referred to as apertured Deltamax memory cell in this paper, operates satisfactorily as a memory element. The fabrication technology is based on etching small holes through a thin Deltamax tape to form memory cells. The operation of the uncompensated and compensated memory cell is investigated. Oscillograms and graphs of the typical characteristics response of the memory cell are presented, and a qualitative description given. The type II and type III elements are found incapable of operating as a memory device because of the magnetic properties of the available tape and magnetic powder. Summaries of type II and III elements are given in Appendix I and II respectively. / Graduation date: 1967 / Best scan available for figures. Original is a photocopy.

To assist in the assessment of the geothermal potential of north-central California and to aid in defining the geologic transitions between the physiographic provinces of the Klamath Range, the Cascade Range, the Modoc Plateau, the Great Valley, and the Sierra Nevada Range, personnel from the Geophysics Group in the College of Oceanography at Oregon State University conducted a detailed aeromagnetic survey extending from 40°15' to 42°00'N latitude and from 120°45' to l22°45'W longitude. Two forms of spectral analysis, the energy spectrum and the exponential methods, were used to make source-top and source-bottom depth calculations. The magnetic source-bottom depths were interpreted as Curie-point isotherm depths. Based on the energy spectrum analysis, several regions with elevated Curie-point isotherm depths were mapped: (1) the Secret Spring Mountain-National Lava Beds Monument area, (2) the Mount Shasta area, (3) the Big Valley Mountains area, and (4) an area northeast of Lassen Peak. The elevated Curie-point isotherm depths within these areas, as shallow as 4 to 7 km below sea level (BSL) in the Secret Spring Mountain-National Lava Beds Monument area, the Mount Shasta area, and the area northeast of Lassen Peak, and 4 to 6 km BSL in the Big Valley Mountains area, imply vertical temperature gradients in excess of 70°C/km and heat flow greater than 100 mW/m² when assuming a Curie-point temperature of 580°C. Shallow source-bottom depths of 4 to 5 km BSL were mapped in the Eddys Mountain area and interpreted to be the depth of a lithologic contact. Source-top depths show that the magnetic basement varies from about 3.5 km BSL, beneath the sedimentary assemblages of the Great Valley and the eastern Klamath Range, to near sea level in the Cascade Range. The exponential approximation method yielded source-bottom depths which agreed, in general, with depths determined by the energy spectrum method. However, this method appears less reliable and its depth estimates less accurate compared to the energy spectrum method. A broad negative anomaly, observed on the total field magnetic intensity map and low-pass filtered anomaly maps, suggests the sedimentary rocks of the Klamath Complex underlie Mount Shasta and the Medicine Lake Highlands. Magnetic lineations are oriented mainly NW. / Graduation date: 1984

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

Graduation date: 2003