To see the other types of publications on this topic, follow the link: Integrated magnetics.
Dissertations / Theses on the topic 'Integrated magnetics'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Integrated magnetics.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Araghchini, Mohammad. "(MEMS) toroidal magnetics for integrated power electronics." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84882.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 237-241).
Power electronics represent a key technology for improving the functionality and performance, and reducing the energy consumption of many systems. However, the size, cost, and performance constraints of conventional power electronics currently limit their use. This is especially true in relatively high-voltage, low-power applications such as off-line power supplies, light-emitting diode (LED) drivers, converters and inverters for photovoltaic panels, and battery interface converters; a LED driver application serves as a motivation example throughout the thesis. Advances in the miniaturization and integration of energy-conversion circuitry in this voltage and power range would have a tremendous impact on many such applications. Magnetic components are often the largest and most expensive components in power electronic circuits and are responsible for a large portion of the power loss. As operating frequencies are increased, the physical size of the passives can, in theory, be reduced while maintaining or improving efficiency. Realizing this reduction in size and the simultaneous improvement in efficiency and power density of power electronic circuits requires improvements in magnetics technology. This thesis focuses on the challenge of improving magnetics through the analysis, optimization, and design of air-core toroidal inductors for integration into high-efficiency, high-frequency power electronic circuits. The first part of the thesis presents the derivation of models for stored energy, resistance and parasitic capacitance of microfabricated toroidal inductors developed for use in integrated power electronics. The models are then reduced to a sinusoidal-steady-state equivalent-circuit model. Two types of toroidal MEMS inductors are considered: in-silicon inductors (with or without silicon core) and in-insulator inductors. These inductors have low profiles and a single-layer winding fabricated via high-aspect-ratio molding and electroplating. Such inductors inevitably have a significant gap between winding turns. This makes the equivalent resistance more difficult to model. The low profile increases the significance of energy stored in the winding which, together with the winding gap, makes the equivalent inductance more difficult to model as well. The models presented in this thesis account for these effects. In the case of in-silicon inductors, magnetically and electrically driven losses in different regions of silicon are modeled analytically as well. The second part of the thesis focuses on the optimized design of microfabricated toroidal inductors for a LED driver. The models developed in the first part of the thesis allow optimization of inductor designs based on objectives such as minimizing substrate area, maximizing efficiency, and simplifying the fabrication process by maximizing minimum feature size. Because the magnetics size and loss depend strongly on the driver design parameters, and the driver performance depends strongly on the inductance value and loss, the simultaneous optimization of driver components and magnetics parameters is used in the design process. The use of computationally efficient models for both magnetics and other circuit components permits numerical optimization using the general co-optimization approach. Finally, a multi-dimensional Pareto-optimal filtering is applied to reduce the feasible design set to those on the multi-objective optimality frontier. For the case of LED drivers, the current state of the art efficiencies range from 65% to 90%. The co-optimization process results in efficiencies greater than 90% while reducing the size of the LED driver by 10 to 100 times compared to the commercially available LED drivers. This is a significant improvement in both the efficiency and the size of the LED drivers. In the resulting designs, the magnetics are no longer the largest part of the circuit. In the third part of the thesis several numerical and experimental tests are presented. The models developed in this thesis, are verified against results from 2D FEA, 3D FEA, direct measurement of MEMS fabricated devices (for both in-insulator devices for flip-chip bonding and in-silicon devices for direct integration), and in-circuit experimentation of the fabricated devices. These tests show that the equivalent-circuit models presented in this thesis have greater accuracy than existing models. The results also show that these models are good enough to support the LED driver optimization.
by Mohammad Araghchini.
Ph.D.
2
Chen, Wei. "Low Voltage High Current Power Conversion with Integrated Magnetics." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30518.
Full textAbstract:
Very low voltage, high current output requirement have necessitated improvements in power supply's density and efficiency. Existing power conversion techniques cannot meet very stringent size and efficiency requirements. By applying the proposed magnetic integration procedure, new integrated magnetic circuits featuring low loss, simple structure, and ripple cancellation technique are then developed to overcome the limitations of prior art. Both cores and windings are integrated. Consequently, the power loss and the size of the integrated magnetic device are greatly reduced. Detailed analysis and design considerations of the proposed circuits are presented. As a result of applying the proposed technique, very high density, high efficiency, low voltage, high current power modules were developed. A typical example features an isolated 3.3V/30A power module with a power density of 130W/in3 and an efficiency of 90% at 500 KHz switching frequency.Ph. D.
3
Reusch, David Clayton. "High Frequency, High Current Integrated Magnetics Design and Analysis." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35420.
Full textAbstract:
The use of computers in the modern world has become prevalent in all aspects of life. The size of these machines has decreased dramatically while the capability has increased exponentially. A special DC-DC converter called a VRM (Voltage Regulator Module) is used to power these machines. The VRM faces the task of supplying high current and high di/dt to the microprocessor while maintaining a tight load regulation. As computers have advanced, so have the VRM's used to power them. Increasing the current and di/dt of the VRM to keep up with the increasing demands of the microprocessor does not come without a cost. To provide the increased di/dt, the VRM must use a higher number of capacitors to supply the transient energy. This is an undesirable solution because of the increased cost and real estate demands this would lead to in the future. Another solution to this problem is to increase the switching frequency and control bandwidth of the VRM. As the switching frequency increases the VRM is faced with efficiency and thermal problems. The current buck topologies suffer large drops in efficiency as the frequency increases from high switching losses.
Resonant or soft switching topologies can provide a relief from the high switching loss for high frequency power conversion. One disadvantage of the resonant schemes is the increased conduction losses produced by the circulating energy required to produce soft switching. As the frequency rises, the additional conduction loss in the resonant schemes can be smaller than the switching loss encountered in the hard switched buck. The topology studied in this work is the 12V non-isolated ZVS self-driven presented in [1]. This scheme offered an increased efficiency over the state of the art industry design and also increased the switching frequency for capacitor reduction. The goal of this research was to study this topology and improve the magnetic design to decrease the cost while maintaining the superior performance.
The magnetics used in resonant converters are very important to the success of the design. Often, the leakage inductance of the magnetics is used to control the ZVS or ZCS switching operation. This work presents a new improved magnetic solution for use in the 12V non-isolated ZVS self-driven scheme which increases circuit operation, flexibility, and production feasibility. The improved magnetic structure is simulated using 3D FEA verification and verified in hardware design.
Master of Science
4
zhou, hua. "MAGNETICS DESIGN FOR HIGH CURRENT LOW VOLTAGE DC/DC CONVERTER." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3381.
Full textAbstract:
With the increasing demand for small and cost efficient DC/DC converters, the power converters are expected to operate with high efficiency. Magnetics components design is one of the biggest challenges in achieving the higher power density and higher efficiency due to the significant portion of magnetics components volume in the whole power system. At the same time, most of the experimental phenomena are related to the magnetics components. So, good magnetics components design is one of the key issues to implement low voltage high current DC/DC converter. Planar technology has many advantages. It has low profile construction, low leakage inductance and inter-winding capacitance, excellent repeatability of parasitic properties, cost efficiency, great reliability, and excellent thermal characteristics. On the other side, however, planar technology also has some disadvantages. Although it improves thermal performance, the planar format increases footprint area. The fact that windings can be placed closer in planar technology to reduce leakage inductance also often has an unwanted effect of increasing parasitic capacitances. In this dissertation, the planar magnetics designs for high current low voltage applications are thoroughly investigated and one CAD design methodology based on FEA numerical analysis is proposed. Because the frequency dependant parasitic parameters of magnetics components are included in the circuit model, the whole circuit analysis is more accurate. When it is implemented correctly, integrated magnetics technique can produce a significant reduction in the magnetic core content number and it can also result in cost efficient designs with less weight and smaller volume. These will increase the whole converter's power density and power efficiency. For high output current and low output voltage applications, half bridge in primary and current doublers in secondary are proved to be a very good solution. Based on this topology, four different integrated magnetics structures are analyzed and compared with each other. One unified model is introduced and implemented in the circuit analysis. A new integrated magnetics component core shape is proposed. All simulation and experimental results verify the integrated magnetics design. There are several new magnetics components applications shown in the dissertation. Active transient voltage compensator is a good solution to the challenging high slew rate load current transient requirement of VRM. The transformer works as an extra voltage source. During the transient periods, the transformer injects or absorbs the extra transient to or from the circuit. A peak current mode controlled integrated magnetics structure is proposed in the dissertation. Two transformers and two inductors are integrated in one core. It can force the two input capacitors of half bridge topology to have the same voltage potential and solve the voltage unbalance issue. The proposed integrated magnetics structure is simple compared with other methods implementing the current mode control to half bridge topology. Circuit analysis, simulation and experimental results verify the feasibility of these applications.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD
5
Garcha, Preetinder(Preetinder Kaur). "Low power circuits with integrated magnetics for sensors and energy harvesting systems." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127019.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 145-151).
The continued expansion of Internet of Things has led to a proliferation of wireless sensors and systems across the globe. The application space for sensors is wide-ranging: from industries, to serve the upcoming era of Industry 4.0, to consumer products, like body wearable sensors. The rise to billions of sensors relies on two key trends in sensor systems: miniaturization and energy-efficiency. This work explores the use of integrated magnetics in microelectronics to enable low power, energy-efficient sensing, as well as energy harvesting to power the sensors, in a compact form factor. For industrial applications, we present the design of a bandwidth-scalable, integrated fluxgate magnetic-to-digital converter for energy-efficient contactless current sensing in smart connectors. The system uses mixed signal front-end design to en-able duty cycling and quick convergence techniques leading to 20x reduction in power consumption at low bandwidths of 1 kHz for power monitoring. It also employs fast read-out circuits to achieve a bandwidth of 125 kHz for machine health diagnosis. For personal body wearable electronics and beyond, we present the design of a cold start system with integrated magnetics for ultra low voltage startup in thermal energy harvesting applications. The Meissner Oscillator analysis with on-chip magnetics allows co-optimization of magnetics and circuits to achieve start up from as low as 25 mV input voltage to the circuits, despite 1000x lower inductance than off-chip transformers. Given the recent push towards artificial intelligence and a growing need for data, along with sensors to collect that data, we need to explore novel uses of technologies to meet the demands for small form factor and low power operation, as the number of sensors scale. The ideas presented in this thesis, with two very different applications of the integrated magnetics technology, can contribute to the continued growth towards trillions of sensors.
by Preetinder Garcha.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
6
Sterk, Douglas Richard. "Compact Isolated High Frequency DC/DC Converters Using Self-Driven Synchronous Rectification." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9648.
Full textAbstract:
In the early 1990's, with the boom of the Internet and the advancements in telecommunications, the demand for high-speed communications systems has reached every corner of the world in forms such as, phone exchanges, the internet servers, routers, and all other types of telecommunication systems. These communication systems demand more data computing, storage, and retrieval capabilities at higher speeds, these demands place a great strain on the power system. To lessen this strain, the existing power architecture must be optimized.
With the arrival of the age of high speed and power hungry microprocessors, the point of load converter has become a necessity. The power delivery architecture has changed from a centralized distribution box delivering an entire system's power to a distributed architecture, in which a common DC bus voltage is distributed and further converted down at the point of load. Two common distributed bus voltages are 12 V for desktop computers and 48 V for telecommunications server applications. As industry strives to design more functionality into each circuit or motherboard, the area available for the point of load converter is continually decreasing. To meet industries demands of more power in smaller sizes power supply designers must increase the converter's switching frequencies. Unfortunately, as the converter switching frequency increases the efficiency is compromised. In particular, the switching, gate drive and body diode related losses proportionally increase with the switching frequency.
This thesis introduces a loss saving self-driven method to drive the secondary side synchronous rectifiers. The loss saving self-driven method introduces two additional transformers that increase the overall footprint of the converter. Also, this thesis proposes a new magnetic integration method to eliminate the need for the two additional gate driver magnetic cores by allowing three discrete power signals to pass through one single magnetic structure. The magnetic integration reduces the overall converter footprint.Master of Science
7
Li, Bin. "High Frequency Bi-directional DC/DC Converter with Integrated Magnetics for Battery Charger Application." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/97874.
Full textAbstract:
Due to the concerns regarding increasing fuel cost and air pollution, plug-in electric vehicles (PEVs) are drawing more and more attention. PEVs have a rechargeable battery that can be restored to full charge by plugging to an external electrical source. However, the commercialization of the PEV is impeded by the demands of a lightweight, compact, yet efficient on-board charger system. Since the state-of-the-art Level 2 on-board charger products are largely silicon (Si)-based, they operate at less than 100 kHz switching frequency, resulting in a low power density at 3-12 W/in3, as well as an efficiency no more than 92 - 94%
Advanced power semiconductor devices have consistently proven to be a major force in pushing the progressive development of power conversion technology. The emerging wide bandgap (WBG) material based power semiconductor devices are considered as game changing devices which can exceed the limit of Si and be used to pursue groundbreaking high frequency, high efficiency, and high power density power conversion.
Using wide bandgap devices, a novel two-stage on-board charger system architecture is proposed at first. The first stage, employing an interleaved bridgeless totem-pole AC/DC in critical conduction mode (CRM) to realize zero voltage switching (ZVS), is operated at over 300 kHz. A bi-directional CLLC resonant converter operating at 500 kHz is chosen for the second stage. Instead of using the conventional fixed 400 V DC-link voltage, a variable DC-link voltage concept is proposed to improve the efficiency within the entire battery voltage range. 1.2 kV SiC devices are adopted for the AC/DC stage and the primary side of DC/DC stage while 650 V GaN devices are used for the secondary side of the DC/DC stage. In addition, a two-stage combined control strategy is adopted to eliminate the double line frequency ripple generated by the AC/DC stage.
The much higher operating frequency of wide bandgap devices also provides us the opportunity to use PCB winding based magnetics due to the reduced voltage-second. Compared with conventional litz-wire based transformer. The manufacture process is greatly simplified and the parasitic is much easier to control. In addition, the resonant inductors are integrated into the PCB transformer so that the total number of magnetic components is reduced. A transformer loss model based on finite element analysis is built and used to optimize the transformer loss and volume to get the best performance under high frequency operation.
Due to the larger inter-winding capacitor of PCB winding transformer, common mode noise becomes a severe issue. A symmetrical resonant converter structure as well as a symmetrical transformer structure is proposed. By utilizing the two transformer cells, the common mode current is cancelled within the transformers and the total system common mode noise can be suppressed.
In order to charge the battery faster, the single-phase on-board charger concept is extended to a higher power level. By using the three-phase interleaved CLLC resonant converter, the charging power is pushed to 12.5 kW. In addition, the integrated PCB winding transformer in single phase is also extended to the three phase. Due to the interleaving between each phase, further integration is achieved and the transformer size is further reduced.PHD
8
Hsiu, Leng-nien. "Low ripple and noise DC/DC converter with quasi-resonant switching and integrated magnetics." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187413.
Full textAbstract:
A low output ripple and noise converter is achieved by employing a zero-voltage switch (ZVS), an integrated magnetics structure which couples a transformer and several coupled inductors in one core, and several auxiliary packaging designs. In the steady-state analysis, the operation of ZVS converter is described and the ZVS switch resonant component design procedure is developed. An optimized geometrical core constant integrated magnetics design procedure is proposed. Some auxiliary packaging design considerations are addressed. The converter ac analysis is divided into two parts to observe the individual small signal effect introduced by the ZVS switch and coupled inductor. The uncoupled-inductor converter ac analysis is conducted by a new approach: an extended circuit averaging method. The converter ac model is obtained by substituting in the coupled inductor ac model to the uncoupled-inductor converter ac model. It is found both the dc coupled inductor zero current ripple condition and the ac converter transfer function response are affected by the turns ratio and the leakage inductance of the coupled inductor. Hence, the converter dc and ac designs are coupled by the coupled inductor operation. Experimental results of the dc and ac analysis of a ZVS converter with coupled inductor are shown. Integrated magnetics achieves less than 3% peak-to-peak current ripple on both coupled inductors at the same time. The equivalent result by separate magnetics approach requires twice the volume implemented by the integrated magnetics structure.
9
Xu, Peng. "Multiphase Voltage Regulator Modules with Magnetic Integration to Power Microprocessors." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26395.
Full textAbstract:
Advances in very large scale integration (VLSI) technologies impose challenges for voltage regulator modules (VRM) to deliver high-quality power to modern microprocessors. As an enabling technology, multiphase converters have become the standard practice in VRM industry. The primary objectives of this dissertation are to develop advanced topologies and innovative integrated magnetics for high-efficiency, high-power-density and fast-transient VRMs. The optimization of multiphase VRMs has also been addressed.
Todayâ s multiphase VRMs are almost universally based on the buck topology. With increased input voltage and decreased output voltage, the multiphase buck converter suffers from a very small duty cycle and cannot achieve a desirable efficiency. The multiphase tapped-inductor buck converter is one of the simplest topologies with a decent duty cycle. However, the leakage inductance of its tapped inductors causes a severe voltage spike problem. An improved topology, named the multiphase coupled-buck converter, is proposed. This innovative topology enables the use of a larger duty cycle with clamped device voltage and recovered leakage energy. Under the same transient responses, the multiphase coupled-buck converter has a significantly better efficiency than the multiphase buck converter.
By integrating all the magnetic components into a single core, in which the windings are wound around the center leg and the air gaps are placed on the two outer legs, it is possible for multiphase VRMs to further improve efficiency and cut the size and cost. Unfortunately, this structure suffers from an undesirable core structure and huge leakage inductance. An improved integrated magnetic structure is proposed to overcome these limitations. All the windings are wound around the two outer legs and the air gap is placed on the center leg. The improved structure also features the flux ripple cancellation in the center leg and strongly reverse-coupled inductors. Both core loss and winding loss are reduced. The steady-state current ripples can be reduced without compromising the transient responses. The overall efficiency of the converter is improved. The input inductor can also be integrated in the improved integrated magnetic structure.
Currently, selecting the appropriate number of channels for multiphase VRMs is still an empirical trial-and-error process. This dissertation proposes a methodology for determining the right number of channels for the optimal multiphase design. The problem formulation and general method for the optimization are proposed. Two examples are performed step by step to demonstrate the proposed optimization methodology. Both are focused on typical VRM 9.0 designs for the latest Pentium 4® microprocessors and their results are compared with the industry practice.Ph. D.
10
Cai, Yinsong. "Optimal Design of MHz LLC Converter for 48V Bus Converter Application." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93582.
Full textAbstract:
The intermediate bus architecture employing the 48V bus converter is one of the most popular power architecture. 48V to 12V bus converter has wide applications in telecommunications, networks, aerospace, and military, etc. However, today's state of the art products has low power rating or power density and becomes difficult to satisfy the demand of increasing power of the loads. To improve the current design, a GaN (Gallium Nitride) based two-stage solution is proposed for the bus converter. The first stage Buck converter regulates the 40V to 60V variable input to a fixed 36V bus voltage. The second stage LLC converter convert the 36V to 12V by a 3:1 transformer. The whole solution achieves the fixed frequency control. The thesis focus on the detail design and optimization of LLC converter, especially its transformer. To have high density and high efficiency, the transformer design becomes critical at MHz frequency. The matrix transformer concept is applied and a merged winding structure is used for flux cancellation, which effectively reduces the AC winding losses. A new fully interleaved termination and via design is proposed. It achieves significant reduction in loss and leakage flux. In addition, to study the current sharing of parallel winding layers, a 1-D analytic model is proposed and a symmetrical winding layer scheme is used to balance the current distribution. The hardware is built and tested. The proposed two-stage converter achieves the best performance compared to the current market.Master of Science
Intermediate bus architecture (IBA) has wide applications in telecommunication, server and computing, and military power supplies. The intermediate bus converter (IBC) is the key stage in the IBA, where the DC bus voltage from the front-end power supply is converted to a lower intermediate bus voltage. Traditional IBC suffers from bulky magnetic components including inductors and transformers. This work illustrates the design and implementation of a two-stage IBC, where the first-stage Buck converter will provide regulation and the second stage LLC converter will provide isolation. Thanks to the soft-switching capability of LLC, the magnetic volume can be significantly reduced by raising the switching frequency of the converter. Therefore, planar magnetics can be used and placed directly inside of the printing circuit board (PCB), which allows for higher power densities and easy manufacturing of the magnetics and overall converter. However, as the frequency goes higher, the AC losses of the transformer caused by the eddy current, skin effect, and proximity effect become dominant. As a result, high-frequency transformer design becomes the key for the converter design. First, matrix transformer concept is applied to distribute the high current and reduce the conduction loss. Second, a novel merged winding structure is proposed for better transformer winding interleaving. Third, a new terminal structure of the transformer is proposed. Finally, the current sharing between parallel windings are modeled and studied. All the efforts result in great loss reduction. The prototype were verified and compared to the current converters that are on the market in the 48V – 12V area of IBCs.
11
Hernandez, Orlando. "Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1158512351.
Full text
12
Nuttall, Daniel Robert. "Advanced high frequency switched-mode power supply techniques and applications." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/advanced-high-frequency-switchedmode-power-supply-techniques-and-applications(5792cb86-58e3-488b-b27e-559c18e55250).html.
Full textAbstract:
This Thesis examines the operation and dynamic performance of a single-stage, single-switch power factor corrector, S4 PFC, with an integrated magnetic device, IM. Also detailed isthe development and analysis of a high power light emitting diode, HP LED, power factorcorrection converter and proposed voltage regulation band control approach.The S4 PFC consists of a cascaded discontinuous current mode, DCM, boost stage anda continuous current mode, CCM, forward converter. The S4 PFC achieves a high powerfactor, low input current harmonics and a regulated voltage output, utilising a singleMOSFET. A steady-state analysis of the S4 PFC with the IM is performed, identifying theoperating boundary conditions for the DCM power factor correction stage and the CCMoutput voltage regulation stage. Integrated magnetic analysis focuses on understanding theperformance, operation and generated flux paths within the IM core, ensuring the device doesnot affect the normal operation of the converter power stage. A design method for the S4 PFCwith IM component is developed along with a cost analysis of this approach. Analysis predictsthe performance of the S4 PFC and the IM, and the theoretical work is validated by MATLABand SABER simulations and measurements of a 180 W prototype converter.It is not only the development of new topological approaches that drives theadvancement of power electronic techniques. The recent emergence of HP LEDs has led to aflurry of new application areas for these devices. A DCM buck-boost converter performs thepower factor correction and energy storage, and a cascaded boundary conduction current modebuck converter regulates the current through the LED arrays. To match the useful operatinglifetime of the HP LEDs, electrolytic capacitors are not used in the PFC converter. Analysisexamines the operation and dynamic characteristics of a PFC converter with low capacitiveenergy storage capacity and its implications on the control method. A modified regulationband control approach is proposed to ensure a high power factor, low input current harmonicsand output voltage regulation of the PFC stage. Small signal analysis describes the dynamicperformance of the PFC converter, Circle Criterion is used to determine the loop stability.Theoretical work is validated by SABER and MATLAB simulations and measurements of a180 W prototype street luminaire.
13
LI, QUAN, and q. li@cqu edu au. "HIGH FREQUENCY TRANSFORMER LINKED CONVERTERS FOR PHOTOVOLTAIC APPLICATIONS." Central Queensland University. N/A, 2006. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20060830.110106.
Full textAbstract:
This thesis examines converter topologies suitable for Module Integrated Converters
(MICs) in grid interactive photovoltaic (PV) systems, and makes a contribution to
the development of the MIC topologies based on the two-inductor boost converter,
which has received less research interest than other well known converters.
The thesis provides a detailed analysis of the resonant two-inductor boost converter
in the MIC implementations with intermediate constant DC links. Under variable
frequency control, this converter is able to operate with a variable DC gain while
maintaining the resonant condition. A similar study is also provided for the resonant
two-inductor boost converter with the voltage clamp, which aims to increase the
output voltage range while reducing the switch voltage stress. An operating point
with minimized power loss can be also established under the fixed load condition.
Both the hard-switched and the soft-switched current fed two-inductor boost
converters are developed for the MIC implementations with unfolding stages. Nondissipative
snubbers and a resonant transition gate drive circuit are respectively
employed in the two converters to minimize the power loss.
The simulation study of a frequency-changer-based two-inductor boost converter is
also provided. This converter features a small non-polarised capacitor in a second
phase output to provide the power balance in single phase inverter applications.
Four magnetic integration solutions for the two-inductor boost converter have also
been presented and they are promising in reducing the converter size and power loss.
14
Ježek, Jaroslav. "Fluxmetr s grafickým zobrazením B-H křivky." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218264.
Full textAbstract:
This work deals with simple fluxmeter which is able, together with other device, to show hysteresis loop. Hysteresis loop is a graphic expression of dependence of magnetic induction on intensity of magnetic field. Oscilloscope is used to display the hysteresis loop. This device is fully sufficient for the display. The measured objects are solenoids from various kinds of materials with the same shape. The main aim of this work is the design, realization and description of the fluxmeter. The fluxmeter consists of several partial blocks. The first one, on which this work is focused, is signal generator which is able to generace different kinds of signal. The generated signal comes on primary winding of solenoid where a magnetic field on a given intensity rises. An amplifier is used to obtain the sufficient intensity. Next thing this work is focused on is the design of the integrator which is necessary for the correct function of the fluxmeter. As suggested, there is shown the block diagram of linking of individual parts. There are described the measured results at the end of this work.
15
Betschon, Felix. "Design principles of integrated magnetic bearings /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13643.
Full text
16
Hussaini, Sheena. "Integrated Magnetic Components for RF Applications." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1431951933.
Full text
17
Oxland, Richard K. "An HBT magnetic sensor with integrated 3-dimensional magnetic structures." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/858/.
Full textAbstract:
The applicability and functionality of high frequency digital and millimetre wave circuits can be enhanced by the integration of sensor elements into the circuits. It is furthermore advantageous to utilise or modify the pre–existing fabrication process flow in creating this added functionality. This thesis describes a work on magnetic field sensors based on an InP/InGaAs heterojunction bipolar transistor (HBT) which has been fabricated to be compatible with high frequency epilayer structure and processes. In this work, the complete fabrication process for the HBT magnetic sensors has been developed, using standard, transferrable process modules. Ohmic contact metallisations were optimised and D.C. electrical characterisations are also reported upon. The effects of several surface treatments on device performance have been studied and characterised. Surface passivation using two distinct sulphur containing compounds of different phases was shown to enhance performance and an ion bombardment process was developed that degraded surface quality and increased surface leakage currents for enhanced sensor performance. In order to improve the sensitivity of an HBT to magnetic field 3–dimensional magnetic structures were designed to be incorporated onto the surface of the extrinsic base. This design process was informed by simulation of magnetic field profiles of the magnetic elements and fabrication processes were created that would allow for arbitrary 3–dimensional structures. The response to magnetic field applied both parallel and perpendicular to the normal of the wafer of an as–fabricated HBT was investigated. Two different emitter structures were compared, a simple square emitter and a multiple finger emitter, and the ability of the devices to resolve applied field angle was uncovered. The effects of device bias on the field response was also looked at and the optimal bias conditions determined. An analysis of the temperature variation of the magnetic field response was conducted with lower temperatures resulting in higher sensitivity to applied field. Finally, the response of an HBT with integrated 3–dimensional magnetic structures was investigated. A passivated device was found to be less sensitive to applied magnetic field and a device treated with ion bombardment to be more sensitive to magnetic field applied parallel to the normal. The signal to noise ratio for an HBT with integrated magnetic structures was 36.4 dB with an equivalent noise of 0.002 T. The maximum magnetic field strength sensitivity was 0.339 T^(−1) and the maximum magnetic field applied angle sensitivity was 0.119 rad^(−1). The maximum change in normalised D.C. current gain was 0.019. A mathematical description of the change in current gain caused by a given magnetic field applied at a given angle was also determined.
18
Ahn, Chong Hyuk. "Micromachined components as integrated inductors and magnetic microactuators." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15367.
Full text
19
Wang, Shen. "Modeling and Design of Planar Integrated Magnetic Components." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34400.
Full textAbstract:
Recently planar magnetic technologies have been widely used in power electronics, due to good cooling and ease of fabrication. High frequency operation of magnetic components is a key to achieve high power density and miniaturization. However, at high frequencies, skin and proximity effect losses in the planar windings become significant, and parasitics cannot be ignored. This piece of work deals with the modeling and design of planar integrated magnetic component for power electronics applications.
First, one-dimensional eddy current analysis in some simple winding strategies is discussed. Two factors are defined in order to quantify the skin and proximity effect contributions as a function of frequency. For complicated structures, 2D and 3D finite element analysis (FEA) is adopted and the accuracy of the simulation results is evaluated against exact analytical solutions.
Then, a planar litz structure is presented. Some definitions and guidelines are established, which form the basis to design a planar litz conductor. It can be constructed by dividing the wide planar conductor into multiple lengthwise strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire. Each strand is subjected to the magnetic field everywhere in the winding window, thereby equalizing the flux linkage. 3D FEA is utilized to investigate the impact of the parameters on the litz performance. The experimental results verify that the planar litz structure can reduce the AC resistance of the planar windings in a specific frequency range.
After that, some important issues related to the planar boost inductor design are described, including core selection, winding configuration, losses estimation, and thermal modeling. Two complete design examples targeting at volume optimization and winding parasitic capacitance minimization are provided, respectively.
This work demonstrates that planar litz conductors are very promising for high frequency planar magnetic components. The optimization of a planar inductor involves a tradeoff between volumetric efficiency and low value of winding capacitance. Throughout, 2D and 3D FEA was indispensable for thermal & electromagnetic modeling.Master of Science
20
Camarda, Antonio <1984>. "Microelectronic Design with Integrated Magnetic and Piezoelectric Structures." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7603/1/Camarda_Antonio_tesi.pdf.
Full textAbstract:
This thesis investigates the possibility of integrating the standard CMOS design process with additional microstructures enhancing circuit functionalities. More specifically, the thesis faces the problem of miniaturization of magnetic and piezoelectric devices mostly focused on the application field of EH (Energy Harvesting) systems and ultra-low power and ultra-low voltage systems.
It shows all the most critical aspects which have to be taken into account during the design process of miniaturized inductors for PwrSoC (Power System on Chip) or transformers. Furthermore it shows that it is possible to optimize the inductance value and also performances by means of a proper choice of the size of the planar core or choosing a different layout shape such as a serpentine shape in place of the classic toroidal one. A new formula for the correct evaluation of the MPL (Magnetic Path Length) was also introduced.
Concerning the piezoelectric counterpart, it is focused on the design and simulation of various MEMS PTs based on a SOI (Silicon on Insulator) structure with AlN (Alluminum Nitride) as active piezoelectric element, in perspective of having a SoC with embedded MEMS devices and circuitry. Furthermore it demonstrates for the first time the use of a PT (Piezoelectric Transformer) for ultra-low voltage EH applications. A new boost oscillator based on a discrete PZT (Lead Zirconate Titanate) PT instead of a MT (Magnetic Transformer) has been modelled and tested on a circuit made up by discrete devices, showing performances comparable to commercial solutions like the LTC3108 from Linear. Furthermore this novel boost oscillator has been designed in a 0.35μm technology by ST Microelectronics, showing better performances as intuitively expected by the developed mathematical model of the entire system.
21
Camarda, Antonio <1984>. "Microelectronic Design with Integrated Magnetic and Piezoelectric Structures." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7603/.
Full textAbstract:
This thesis investigates the possibility of integrating the standard CMOS design process with additional microstructures enhancing circuit functionalities. More specifically, the thesis faces the problem of miniaturization of magnetic and piezoelectric devices mostly focused on the application field of EH (Energy Harvesting) systems and ultra-low power and ultra-low voltage systems.
It shows all the most critical aspects which have to be taken into account during the design process of miniaturized inductors for PwrSoC (Power System on Chip) or transformers. Furthermore it shows that it is possible to optimize the inductance value and also performances by means of a proper choice of the size of the planar core or choosing a different layout shape such as a serpentine shape in place of the classic toroidal one. A new formula for the correct evaluation of the MPL (Magnetic Path Length) was also introduced.
Concerning the piezoelectric counterpart, it is focused on the design and simulation of various MEMS PTs based on a SOI (Silicon on Insulator) structure with AlN (Alluminum Nitride) as active piezoelectric element, in perspective of having a SoC with embedded MEMS devices and circuitry. Furthermore it demonstrates for the first time the use of a PT (Piezoelectric Transformer) for ultra-low voltage EH applications. A new boost oscillator based on a discrete PZT (Lead Zirconate Titanate) PT instead of a MT (Magnetic Transformer) has been modelled and tested on a circuit made up by discrete devices, showing performances comparable to commercial solutions like the LTC3108 from Linear. Furthermore this novel boost oscillator has been designed in a 0.35μm technology by ST Microelectronics, showing better performances as intuitively expected by the developed mathematical model of the entire system.
22
CHOI, JIN-WOO. "MAGNETIC PARTICLE SEPARATORS AND INTEGRATED BIOFILTERS FOR MAGNETIC BEAD-BASED BIOCHEMICAL DETECTION SYSTEM." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990796344.
Full text
23
Guo, Wei. "Compact modeling of magnetic tunnel junctions and design of hybrid CMOS-magnetic integrated circuits." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0126.
Full textAbstract:
Le but de cette thèse était d’évaluer les performances de circuits logiques combinant des composants CMOS classiques et des composants magnétiques. Les jonctions tunnel magnétiques sont bien connues comme éléments de base des mémoires magnétiques. Mais l’utilisation de ces composants non-volatiles peut également permettre de repousser certaines limites de la microélectronique actuelle, notamment en contribuant à diminuer la consommation, les problèmes de dissipation thermique, en améliorant la fiabilité des circuits et en apportant de nouvelles fonctionnalités. Cette thèse a consisté en deux principaux aspects. Tout d’abord, un modèle électrique équivalent de la jonction tunnel magnétique a été développé afin de pouvoir les utiliser dans les outils standards de la microélectronique. Ensuite, ces modèles ont été utilisés pour concevoir et évaluer différents circuits hybrides CMOS/magnétiques, reprogrammables ou de type ASICs, qui ont été implémentés dans des démonstrateurs
24
Li, Liangliang. "Nanogranular soft magnetic material and on-package integrated inductors /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full text
25
Nathan, Kumaran Saenthan. "A novel DC-DC converter for photovoltaic applications." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288881.
Full textAbstract:
Growing concerns about climate change have led to the world experiencing an unprecedented push towards renewable energy. Economic drivers and government policies mean that small, distributed forms of generation, like solar photovoltaics, will play a large role in our transition to a clean energy future. In this thesis, a novel DC-DC converter known as the Coupled Inductors Combined Cuk-SEPIC' (CI-CCS) converter is explored, which is particularly attractive for these photovoltaic applications. A topological modification is investigated which provides several benefits, including increased power density, efficiency, and operational advantages for solar energy conversion. The converter, which is based on the combination of the Cuk and SEPIC converters, provides a bipolar output (i.e. both positive and negative voltages). This converter also offers both step-up and step-down capabilities with a continuous input current, and uses only a single, ground-referenced switching device. A significant enhancement to this converter is proposed: magnetic coupling of the converter's three inductors. This can substantially reduce the CI-CCS converter's input current ripple - an important benefit for maximum power point tracking (MPPT) in photovoltaic applications. The effect of this coupling is examined theoretically, and optimisations are performed - both analytically and in simulations - to inform the design of a 4 kW prototype CI-CCS converter, switched at a high frequency (100 kHz) with a silicon carbide (SiC) MOSFET. Simulation and experimental results are then presented to demonstrate the CI-CCS converter's operation and highlight the benefits of coupling its inductors. An efficiency analysis is also undertaken and its sources of losses are quantified. The converter is subsequently integrated into a domestic photovoltaic system to provide a practical demonstration of its suitability for such applications. MPPT is integrated into the CI-CCS DC-DC converter, and a combined half bridge/T-type converter is developed and paired with the CI-CCS converter to form an entirely transformerless single-phase solar energy conversion system. The combination of the CI-CCS converter's bipolar DC output with the combined half bridge/T-type converter's bipolar DC input allows grounding at both the photovoltaic panels and the AC grid's neutral point. This eliminates high frequency common mode voltages from the PV array, which in turn prevents leakage currents. The entire system can be operated in grid-connected mode - where the objective is to maximise power extracted from the photovoltaic system, and is demonstrated in stand-alone mode - where the objective is to match solar generation with the load's power demands.
26
Syed, Azeemuddin. "Permalloy magnetic domain control for radio frequency integrated circuit applications /." Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1079666501&sid=10&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Full text
27
Park, Jae Yeong. "Packaging-compatible micromachined magnetic devices : integrated passive components and modules." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16385.
Full text
28
Kiermaier, Josef [Verfasser]. "Integrated Nanomagnetic Logic System in Perpendicular Magnetic Media / Josef Kiermaier." Aachen : Shaker, 2014. http://d-nb.info/1049380894/34.
Full text
29
Yu, Xuehong. "Silicon-embedded magnetic components for on-chip integrated power applications." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54243.
Full textAbstract:
The objective of the proposed research is to design, fabricate, characterize and test silicon-embedded magnetic components for on-chip integrated power applications.
Driven by the trend towards continued system multi-functionality and miniaturization, MEMS technology can be used to enable fabrication of three-dimensional (3-D) functional devices into the silicon bulk, taking advantage of the 'dead volume' in the substrate and achieving a greater level of miniaturization and integration. As an example, one of the challenges in realizing ultra-compact high-frequency power converters lies in the integration of magnetic components due to their relatively large volume.
Embedding 3-D magnetic components within the wafer volume and implementing high-power, through-wafer interconnect for connection to circuitry on the wafer surface is a promising solution for achieving ultra-compact power converters, in which digital control circuitry and power switches are located on the wafer surface, and suitable magnetic components are embedded within the silicon substrate. In order to do this, key tasks in the following areas have been accomplished: development of new fabrication technologies for silicon embedding and 3-D structure realization; creation of high-current, through-wafer interconnects for connection of the device to circuitry; ability to incorporate a variety of magnetic materials when performance enhancement of the device is needed; exploration of a new design space for the devices due to ultra-compactness and silicon interaction; understanding of the complicated loss mechanisms in the embedded devices; and demonstration of device performance and in-circuit operation.
30
Hartman, Gregory. "Monolithically integrated non-reciprocal devices based on magnetic thin films." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369095798.
Full text
31
Zhang, Tong. "An integrated framework for magnetic resonance image reconstruction and segmentation." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15457.
Full textAbstract:
As a non-invasive tomographic imaging technology, magnetic resonance imaging (MRI) has revolutionized the diagnostic imaging industry. Due to its relatively high resolution and superior soft-tissue contrast, MRI has been widely used for human health monitoring, disease diagnosis, and clinical research. The traditional medical imaging technologies aim to reconstruct the image from measured signals for visualisation of the inside body. However, the reconstructed image is just a foundation for disease diagnosis and/or health assessment of the patient, which will be subsequently interpreted and analysed either by human experts or computer based examinations. Despite the fact that the correlations between image reconstruction and image analysis can be very useful for signal acquisition and result interpretation, the related studies are rarely reported in the literature. Therefore, this thesis aims to first identify the knowledge gaps in image reconstruction and analysis, then to correlate their mutual information, and consequently propose integrated learning and analysing methods to improve the current separated routines. To begin with, current MRI technology suffers from its relatively slow imaging speed. Unlike x-ray or computed tomography in which image slices are acquired in parallel, MR signal is collected in k-space, a spatial frequency domain, sequentially in time within one slice. A straightforward solution to accelerate the imaging speed is to reconstruct the image from under-sampled k-space measurements. As a promising fast imaging method, compressive sensing MRI (CS-MRI) frameworks have been developed. Such techniques attempt to find the sparsest data representation obtained in certain basis/dictionaries, and thus are able to reduce the data acquisition time. Compared to the mathematical dictionaries, the recently developed data adaptive dictionary learning methods generate the start-of-art results. It should be noted that, besides the data sparsity, the non-linear and discriminative features, which are commonly used as prior knowledge for image analysis, are rarely investigated. Under this motivation, this thesis will study how to facilitate those useful features to improve the reconstruction performances. Specifically, a kernel based multi-dictionary learning (KMDL) approach is proposed, which can model both the non-linear characteristics and the discriminative features embedded in the images of both training and testing data sets. On the other hand, image segmentation, which aims to separate different tissues or regions of interest, usually serves as a basic step in computer aided diagnosis systems and fundamentally influences their performances. Due to the commonly existing image artefacts, i.e., noises and intensity inhomogeneity in MR images, accurate image segmentation is very challenging. This thesis will propose and develop four image segmentation algorithms for brain MRI scans, namely, a deformable co-segmentation algorithm, a statistical segmentation approach using clonal selection algorithm (GMM-CSA), a hidden Markov random field model based algorithm (HMRF-CSA), and a patch based kernel dictionary learning (PBKDL) algorithm. These methods integrate spatial prior knowledge, e.g. probabilistic brain atlas, and statistical information into the model based segmentation routines. Numerical experiments are conducted using both simulated and clinical brain MR images. The segmentation performances of the proposed approaches are comparable to other state-of-the-art algorithms. Last but not least, this thesis will jointly investigate the image reconstruction and segmentation methods, which are traditionally researched and practised independently. Evidently, the quality of image reconstruction will influence the image segmentation results. Specifically, fast MRI techniques unavoidably deteriorate image quality, which will negatively affect the performances of image segmentation and computer based image analysis. In contrast, the discriminative features extracted from image segmentation results can be useful for the image reconstruction. Therefore, this thesis will explore the correlations between MR image reconstruction and segmentation, leverage the information embedded in both frequency and image domains, and propose an integrated framework. Our results show that the proposed integrated framework is very promising and can be used to form the future intelligent imaging paradigm.
32
Stegen, Sascha. "Development of an Integrated Magnetic System Assisted by Electromagnetic Simulation." Thesis, Griffith University, 2012. http://hdl.handle.net/10072/365703.
Full textAbstract:
In DC/DC converter systems, power electronic circuits are reaching switching efficiencies close to 100 percent nowadays. Thus, most of the energy loss appears inside the passive magnetic circuit of the converter, which at the same time is the component that requires most space in the system. In order to battle this issue, research during the last century has been focused on planarization, hybridization and integration techniques with the goal to achieve higher efficiencies and decrease the profile and volume of the devices. In addition, higher frequencies have been applied to achieve a higher power density of the magnetic systems, but with the negative consequence of stronger parasitic effects such as proximity and skin effects inside the magnetic circuit.
This thesis deals with the development of an integrated magnetic system in a L-C-T (Inductor-Capacitor-Transformer) configuration, with the assistance of Finite Element Method (FEM) computer modeling, which is supportively used to accelerate the development process. Computational simulation method is used to indicate and address the physical issues, which cannot be identified with conventional measurement methods.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
33
Chan, Wai-san. "Design and analysis of integrated computational imaging systems." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38960357.
Full text
34
Cooper, A. R. "An integrated approach to silicon transducers : magnetic field as an example." Thesis, University of Southampton, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356052.
Full text
35
Sathe, Tushar R. "Integrated Magnetic and Optical Nanotechnology for Early Cancer Detection and Monitoring." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19868.
Full textAbstract:
Despite significant developments in imaging modalities and therapeutics, cancer mortality rates remain unchanged. Detecting cancer before it has spread to other organs improves patient outcome dramatically. Therefore, greater emphasis must be placed on developing novel technology for early cancer detection and disease monitoring. Nanometer-sized materials have unique optoelectronic and magnetic properties. In particular, semiconductor quantum dots (QD) are a new class of fluorophores that are bright, photostable, and can be simultaneously excited to emit different wavelengths of light. Magnetic iron oxide nanoparticles are another class of unique nanomaterials that exhibit superparamagnetism and are strongly magnetized only in the presence of a magnetic field.
In this dissertation, we describe the integration of semiconductor QDs and magnetic iron oxide nanoparticles and potential applications for (i) early detection of cancer biomarkers through routine screening, and (ii) disease monitoring through the capture and analysis of rare circulating tumor cells. First, we describe the development of integrated magneto-optical beads that can be optically encoded and magnetically separable for isolating low amounts of biomolecules from solution. Second, we demonstrate improved detection sensitivity by combining immunomagnetic beads and highly luminescent nanoparticles in a sandwich assay. Next, we describe integration of magnetic and QD nanotechnology for the selective capture and molecular profiling of rare cells. We demonstrate the ability to spectroscopically determine relative molecular levels of markers to identify invasive cells. As disease monitoring requires the analysis of patient blood samples, we have also studied nanoparticle-cell interactions using QDs to determine nanoparticle behavior in whole blood as a function of surface coatings. We observed that anionic nanoparticles with carboxylic acid groups (-COOH) were strongly associated with leukocytes, but interestingly this association was cell specific. Hydroxyl-modified QDs (QD-OH) suppressed binding and uptake by leukocytes as efficiently as PEG-modified QDs. The integration of nanotechnologies represents a new and exciting approach that has the potential to push the limits of detection sensitivity and permit isolation and profiling of multiple biomarkers from large sample volumes.
36
Bowers, Brian J. (Brian Jeffrey). "Integrated cryogenic refrigeration system design for superconducting magnetic energy storage systems." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42681.
Full text
37
Hardy, M. J. "Integrated surface plasmon generator for application in heat assisted magnetic recording." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676510.
Full textAbstract:
Presented here is a novel design for a vertical cavity surface emitting laser for supplying heat to a recording medium in a magnetic recording drive, in an attempt to overcome the superparamagnetic limit. Included in the thesis is a discussion of the requirement for a system to focus energy beyond the diffraction limit and onto a recording platter. Plasmonics is introduced as a method to achieve this focusing and the structure to be used in this work is presented. Initial modelling of the structure for a theoretical efficiency and hence feasibility of the design is then conducted. Fabrication of the device is discussed in detail and preliminary characterisation of the device is undertaken.
38
Ayhan, Mustafa Tufan. "Design And Implementation Of Coupled Inductor Cuk Converter Operating In Continuous Conduction Mode." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613927/index.pdf.
Full textAbstract:
The study involves the following stages: First, coupled-inductor and integrated magnetic structure used in Cuk converter circuit topologies are analyzed and the necessary information about these elements in circuit design is gathered. Also, benefits of using these magnetic elements are presented. Secondlysteady-state model, dynamic model and transfer functions of coupled-inductor Cuk converter topology are obtained via state-space averaging method. Third stage deals with determining the design criteria to be fulfilled by the implemented circuit. The selection of the circuit components and the design of the coupled-inductor providing ripple-free input current waveform are performed at this stage. Fourth stage introduces the experimental results of the implemented circuit operating in open loop mode. Besides, the controller design is carried out and the closed loop performance of the implemented circuit is presented in this stage.
39
Jones, Hannah Amy. "Sediments in urbanised river catchments : an integrated sedimentological and magnetic mineral approach." Thesis, Manchester Metropolitan University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412634.
Full text
40
Mukherjee, Sankha S. "Realization of CoFeB/MgO/CoFeB magnetic tunnel junction devices through materials analysis, process integration and circuit simulation /." Online version of thesis, 2009. http://hdl.handle.net/1850/11336.
Full text
41
Taylor, John-Philip. "Integrated, FPGA based NMR teslameter and power supply for accelerator magnets /." Link to the online version, 2007. http://hdl.handle.net/10019/470.
Full text
42
Chan, Wai-san, and 陳慧珊. "Design and analysis of integrated computational imaging systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38960357.
Full text
43
Tobgay, Sonam. "Novel concepts for RF surface coils with integrated receivers." Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0419104-141545.
Full text
44
Topal, Tankut. "A Labview Interface To Integrate Magnetic Resonance Imaging (mri) Simulator With System Control And Its Application To Regional Magnetic Resonance Electrical Impedance Tomography (mreit) Reconstruction." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612246/index.pdf.
Full textAbstract:
Magnetic resonance imaging (MRI) is a high resolution medical imaging technique based on distinguishing tissues according to their nuclear magnetic properties. Magnetic resonance electrical impedance tomography (MREIT) is a conductivity imaging technique which reconstructs images of electrical properties, based on their effect on induced magnetic flux density due to externally applied current flow. Both of these techniques are of interest for novel research and development. Simulators help researchers observe the accuracy and the results of the study. In this study a user friendly complete MRI/MREIT simulator is designed. This simulator is the combination of improved version of MRI simulator (implemented by V. E. Arpinar, H. Yigitler), a forward solver, to observe the current injection effect, the improved version of user interface that is designed on LabVIEW graphical programming environment (designed by M. Ozsut), and equi-potential projection (EPP) reconstruction algorithm (proposed by M. S. Ozdemir, M. Eyuboglu, O. Ozbek). All of these individual parts are improved and gathered in LabVIEW environment in order to work in synchrony. In addition to that, regional image reconstruction technique (proposed by H. Altunel, M. Eyuboglu) is also included in the simulator.
The simulator is run for various inputs and system specifications. It is observed that the simulation results are consistent with the expected results for MRI, MREIT and conventional/regional MREIT reconstruction. Four different models are designed and results are obtained using these models. The accuracy of the results usually differs with the input parameters and model geometry. Validating numerically the accuracy of the forward solution part using Biot-Savart and Ampere's laws, the consistency of the forward problem solution part is obtained at a percentage of 95%. In the MREIT part, magnetic flux density distribution taken from forward solver part is added to the main magnetic flux density used in the MRI part. Consistency of the magnetic flux density distribution given to the simulator as input and the output taken from the MREIT part of the simulator is found as 99%. In addition to conventional EPP algorithm, regional MREIT reconstruction algorithm is applied for various noise levels. It is observed that, as the noise level increases, regional MREIT reconstruction algorithm gives relatively much better results compared to conventional MREIT reconstruction algorithm. Errors obtained by applying conventional reconstruction and regional reconstruction are compared for each inhomogeneity individually. Therefore, accuracies of the different current patterns depending on the inhomogeneities are observed as well.
45
Andersson, Magnus. "3D Structure and Emplacement of the Alnö Alkaline and Carbonatite Complex, Sweden : Integrated Geophysical and Physical Property Investigations." Doctoral thesis, Uppsala universitet, Geofysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-248113.
Full textAbstract:
Carbonatites are carbonate-rich magmatic rocks that are rare and of great relevance for our understanding of crustal and mantle processes. Although found on all continents and in settings ranging from Archaean to present-day, their deeper plumbing system is still poorly understood. Therefore, the main goal of this thesis is to broaden the existing knowledge of carbonatite systems, often limited to surface geological observations, by providing depth constraints using a number of geophysical methods and petrophysical measurements. The Alnö alkaline and carbonatite complex in central Sweden was chosen for this purpose. Data from three reflection seismic lines, ground gravity and magnetic measurements are presented. These data are complemented by a series of petrophysical measurements, including ultrasonic velocities, density, magnetic bulk susceptibility, anisotropy of magnetic susceptibility (AMS), and magnetic remanence, to aid in the interpretation of the geophysical data. The reflection seismic data indicate a solidified saucer-shaped fossil magma chamber at about 3 km depth. Caldera-style volcanism, constrained by surface geological observations, provides a plausible scenario to explain the emplacement of the complex, suggesting that carbonatite magmas have been stored, transported and erupted in a similar manner to known emplacement mechanisms for silicic calderas, although these are compositionally different. The AMS data from most of the carbonatite sheets in Alnö show a strong degree of anisotropy and oblate-shaped susceptibility ellipsoids. A set of syn- and post-emplacement processes that may control the AMS signature is evaluated based on the dataset. Overprinting of the primary flow patterns by processes related to sheet closure at the terminal stage of magma transport may explain the AMS observations. A complementary study using 3D inversion of ground gravity and aeromagnetic data was then carried out to better delineate the 3D internal architecture of the complex. Resulting models indicate a depth extent of the complex to about 3-4 km, consistent with the interpretation of the reflection seismic data. The modelling results of a ring-shaped magnetic anomaly observed in the Klingefjärden bay adjacent to Alnö Island further suggest that the complex may extend laterally about 3 km towards the north.
46
Chai, Joshua Tian-Yun. "Integrated characterisation of carotid atherosclerosis : from magnetic resonance imaging to plaque macrophage profiling." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:3c3ca86b-8abf-4b3e-b2a2-d59a3ab604a4.
Full textAbstract:
Cardiovascular morbidity and mortality remain the most serious global public health challenge. With the evolution in global socio-economic activities and the associated lifestyle changes, there is an impending epidemic of obesity, insulin resistance, metabolic syndrome, and diabetes mellitus, all of which fuel premature coronary artery disease and stroke. In the post-statin era, despite considerable efforts in anti-atherosclerotic drug development, a significant number of these potential compounds with initial success in early phase clinical studies failed to translate to clinical outcome benefits. This shows a disparity of various biomarkers and molecular disease mechanisms, and highlighted the inadequacy of current methods of risk stratification and atherosclerosis characterisation. Atherosclerosis imaging such as by MRI does not only serve as 'gate keepers' in the contemporary drug development process; but in combination with modern "omics", would allow precise disease stratification with resolution never achieved before. This integrated characterisation of atherosclerosis will generate novel insights about plaque biology, bridge the gap between molecular insights and clinical outcomes, and help achieve the goal of stratified, personalized, medicine. This thesis hypothesized that plaque compositional heterogeneity such as lipid content is associated with specific gene expression profiles or signatures in human carotid plaque macrophages in a spatially distinct pattern; and that this macrophage functional heterogeneity may in turn play a role in altering response to anti-atherosclerotic treatment. To test these hypotheses, human subjects with carotid atherosclerosis were recruited before carotid surgery and scanned using novel MRI T2 mapping technique. Explanted carotid plaques were then examined by immunohistochemistry-guided laser capture microdissection and microarray analysis. T2 mapping was shown to be able to accurately and reproducibly discriminate all major plaque components, and in particular, quantify plaque lipid content with excellent histological validation. Symptomatic plaques were shown to contain larger lipid-core by T2 mapping compared to asymptomatic plaques, despite similar degree of luminal stenosis. Macrophages from the same cohorts of plaques were procured by immunohistochemistry-guided laser capture microdissection and they were shown to display distinct gene expression profiles based on their micro-anatomical locations and clinical presentations; importantly, macrophages from plaques with high lipid content detected by T2 mapping were found to activate specific interferon / STAT1 pathways. Finally, using nicotinic acid as an example, the functional significance of plaque macrophage heterogeneity was shown in vitro to affect response to pharmacological intervention.
47
Shihadeh, Fadi Easa. "Optimized and integrated alignment system for functional proton radiosurgery." CSUSB ScholarWorks, 2007. https://scholarworks.lib.csusb.edu/etd-project/3258.
Full textAbstract:
In this thesis work, a system for proton beam alignment was studied and optimized in many of its functional areas. The resulting system was named Positioning Alignment Control System (PACS). The PACS system is an integrated and efficient system as a result of the work done on it in the course of this thesis work.
48
Pandharpure, Shrinivas. "Process development for integration of CoFeB/MgO-based magnetic tunnel junction (MTJ) device on silicon /." Online version of thesis, 2007. http://hdl.handle.net/1850/5060.
Full text
49
Taylor, John-Philip. "Integrated, FPGA Based NMR Teslameter and power supply for accelerator magnets." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2308.
Full textAbstract:
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2007.Particle accelerators today have numerous magnets that require controlling. These include magnets for analysing, beam-path selection, focusing, etc. Also, design specifications are becoming tighter. A typical modern magnet power supply is expected to have a resolution of 16-bit and a stability of 10 ppm. This thesis addresses two research areas. First, various aspects of high-performance accelerator magnet power supplies are investigated. An isolated dual-stage 3.5 kW converter is designed. The concept is verified through practical measurements. The control system and high-resolution pulse-width modulation are implemented within a field-programmable gate array. Second, a nuclear-magnetic resonance probe is designed and simulated. It is intended to provide a measurement of field-strength for feed-back purposes. Some adjustments are made with existing technology in order to decrease the time between successive measurements to the order of 10 μs. Also, the support systems (central processing unit, hardware drivers, etc.) are designed, implemented in the field-programmable gate array and tested successfully.
50
Sanchez, Antequera Yolanda. "Magselectofection: A novel integrated technology of magnetic separation and genetic modification of target cells." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-127469.
Full text