Dissertations / Theses on the topic 'Electrical and Electronic Engineering'
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Navaraj, William Ringal Taube. "Inorganic micro/nanostructures-based high-performance flexible electronics for electronic skin application." Thesis, University of Glasgow, 2019. http://theses.gla.ac.uk/40973/.
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Electronics in the future will be printed on diverse substrates, benefiting several emerging applications such as electronic skin (e-skin) for robotics/prosthetics, flexible displays, flexible/conformable biosensors, large area electronics, and implantable devices. For such applications, electronics based on inorganic micro/nanostructures (IMNSs) from high mobility materials such as single crystal silicon and compound semiconductors in the form of ultrathin chips, membranes, nanoribbons (NRs), nanowires (NWs) etc., offer promising high-performance solutions compared to conventional organic materials. This thesis presents an investigation of the various forms of IMNSs for high-performance electronics. Active components (from Silicon) and sensor components (from indium tin oxide (ITO), vanadium pentaoxide (V2O5), and zinc oxide (ZnO)) were realised based on the IMNS for application in artificial tactile skin for prosthetics/robotics. Inspired by human tactile sensing, a capacitive-piezoelectric tandem architecture was realised with indium tin oxide (ITO) on a flexible polymer sheet for achieving static (upto 0.25 kPa-1 sensitivity) and dynamic (2.28 kPa-1 sensitivity) tactile sensing. These passive tactile sensors were interfaced in extended gate mode with flexible high-performance metal oxide semiconductor field effect transistors (MOSFETs) fabricated through a scalable process. The developed process enabled wafer scale transfer of ultrathin chips (UTCs) of silicon with various devices (ultrathin chip resistive samples, metal oxide semiconductor (MOS) capacitors and n‐channel MOSFETs) on flexible substrates up to 4" diameter. The devices were capable of bending upto 1.437 mm radius of curvature and exhibited surface mobility above 330 cm2/V-s, on-to-off current ratios above 4.32 decades, and a subthreshold slope above 0.98 V/decade, under various bending conditions. While UTCs are useful for realizing high-density high-performance micro-electronics on small areas, high-performance electronics on large area flexible substrates along with low-cost fabrication techniques are also important for realizing e-skin. In this regard, two other IMNS forms are investigated in this thesis, namely, NWs and NRs. The controlled selective source/drain doping needed to obtain transistors from such structure remains a bottleneck during post transfer printing. An attractive solution to address this challenge based on junctionless FETs (JLFETs), is investigated in this thesis via technology computer-aided design (TCAD) simulation and practical fabrication. The TCAD optimization implies a current of 3.36 mA for a 15 μm channel length, 40 μm channel width with an on-to-off ratio of 4.02x 107. Similar to the NRs, NWs are also suitable for realizing high performance e-skin. NWs of various sizes, distribution and length have been fabricated using various nano-patterning methods followed by metal assisted chemical etching (MACE). Synthesis of Si NWs of diameter as low as 10 nm and of aspect ratio more than 200:1 was achieved. Apart from Si NWs, V2O5 and ZnO NWs were also explored for sensor applications. Two approaches were investigated for printing NWs on flexible substrates namely (i) contact printing and (ii) large-area dielectrophoresis (DEP) assisted transfer printing. Both approaches were used to realize electronic layers with high NW density. The former approach resulted in 7 NWs/μm for bottom-up ZnO and 3 NWs/μm for top-down Si NWs while the latter approach resulted in 7 NWs/μm with simultaneous assembly on 30x30 electrode patterns in a 3 cm x 3 cm area. The contact-printing system was used to fabricate ZnO and Si NW-based ultraviolet (UV) photodetectors (PDs) with a Wheatstone bridge (WB) configuration. The assembled V2O5 NWs were used to realize temperature sensors with sensitivity of 0.03% /K. The sensor arrays are suitable for tactile e-skin application. While the above focuses on realizing conventional sensing and addressing elements for e-skin, processing of a large amount of data from e-skin has remained a challenge, especially in the case of large area skin. A Neural NW Field Effect Transistors (υ-NWFETs) based hardware-implementable neural network (HNN) approach for tactile data processing in e-skin is presented in the final part of this thesis. The concept is evaluated by interfacing with a fabricated kirigami-inspired e-skin. Apart from e-skin for prosthetics and robotics, the presented research will also be useful for obtaining high performance flexible circuits needed in many futuristic flexible electronics applications such as smart surgical tools, biosensors, implantable electronics/electroceuticals and flexible mobile phones.
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Galda, Alexey. "Electronic properties of Luttinger Liquid with electron-phonon interaction." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4293/.
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This thesis addresses a theoretical study of the problem of a single impurity embedded in a one-dimensional system of interacting electrons in presence of electron-phonon coupling. First we consider a system with a featureless point-like potential impurity, followed by the case of a resonant level hybridised with a Luttinger Liquid. The stress is made on a more fundamental problem of a featureless scatterer, for which two opposite limits in the impurity strength are considered: a weak scatterer and a weak link. We have found that, regardless of the transmission properties of phonons through the impurity, the scaling dimensions of the conductance in these limits obey the duality condition, \( \triangle_{WS}\) \( \triangle_{WL}\) = 1, known for the Luttinger Liquid in the absence of phonons. However, in the case when the strength of phonon scattering is correlated with electron scattering by the impurity, we find a nontrivial phase diagram with up to three fixed points and a possibility of a metal-insulator transition. We also consider the case of a weakly interacting electron-phonon system in the presence of a single impurity of an arbitrary scattering potential. In the problem of a resonant level attached to the Luttinger Liquid we show that the electron-phonon coupling significantly modifies the effective energy-dependent width of the resonant level in two different geometries, corresponding to the resonant and anti-resonant transmission in the Fermi gas.
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Larsson, Erik, and Niklas Kron. "Independent project in electrical engineering : Magnetic hand timepiece." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325637.
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Paine, Stephen Thomas. "Electronic countermeasures applied to passive radar." Doctoral thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30945.
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Passive Radar (PR) is a form of bistatic radar that utilises existing transmitter infrastructure such as FM radio, digital audio and video broadcasts (DAB and DVB-T/T2), cellular base station transmitters, and satellite-borne illuminators like DVB-S instead of a dedicated radar transmitter. Extensive research into PR has been performed over the last two decades across various industries with the technology maturing to a point where it is becoming commercially viable. Nevertheless, despite the abundance of PR literature, there is a scarcity of open literature pertaining to electronic countermeasures (ECM) applied to PR. This research makes the novel contribution of a comprehensive exploration and validation of various ECM techniques and their effectiveness when applied to PR. Extensive research has been conducted to assess the inherent properties of the lluminators of Opportunity to identify their possible weaknesses for the purpose of applying targeted ECM. Similarly, potential jamming signals have also been researched to evaluate their effectiveness as bespoke ECM signals. Whilst different types of PR exist, this thesis focuses specifically on ECM applied to FM radio and DVB-T2 based PR. The results show noise jamming to be effective against FM radio based PR where jamming can be achieved with relatively low jamming power. A waveform study is performed to determine the optimal jamming waveform for an FM radio based PR. The importance of an effective direct signal interference (DSI) canceller is also shown as a means of suppressing the jamming signal. A basic overview of counter-ECM (ECCM) is discussed to counter potential jamming of FM based PR. The two main processing techniques for DVB-T2 based PR, mismatched and inverse filtering, have been investigated and their performance in the presence of jamming evaluated. The deterministic components of the DVB-T2 waveform are shown to be an effective form of attack for both mismatched filtering and inverse filtering techniques. Basic ECCM is also presented to counter potential pilot attacks on DVB-T2 based PR. Using measured data from a PR demonstrator, the application and effectiveness of each jamming technique is clearly demonstrated, evaluated and quantified.
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Siebert, Wolfgang Peter. "Alternative electronic packaging concepts for high frequency electronics." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-223.
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Lund, Richard. "Multilevel Power Electronic Converters for Electrical motor Drives." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-687.
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Power electronic converters are widely used in industrial power conversion systems both for utility and drives applications. As the power level increases, the voltage level is increased accordingly to obtain satisfactory efficiency. During the last years, the voltage rating of fast switching high voltage semiconductors such as the Insulated Gate Bipolar Transistor (IGBT) has increased. Still, there is a need for series connection of switching devices. In this area of applications, the Multilevel Converter has shown growing popularity.
The fundamental advantages of the Multilevel Converter topologies are low distorted output waveforms and limited voltage stress on the switching devices. The main disadvantages are higher complexity and more difficult control.
In this thesis, Multilevel Converters are analysed for large motor drive applications. The main focus has been on converter losses, output waveform quality and control.
Analytical expressions for both switching and conduction losses for 4- and 5-level Diode Clamped Converters have been developed. The investigation shows that the losses can be reduced by utilizing a multilevel topology for a 1 MW drive. This work is presented in [46]. The same reduction in losses is proven for a 2300V/ 3 MW drive.
Analytical expressions for the harmonic losses in 3-level converters have been developed for 2 different Carrier Based PWM schemes, presented in [56], [57] and [58]. Also Space Vector PWM are investigated and compared by simulations, in addition to 4- and 5-level Carrier Based PWM.
DC-bus balancing in both 3- and 5-level converters is discussed. Balancing in 3- level converters can be achieved by proper control. Balancing in 5-level converters can be achieved by proper arrangement of isolated DC-supplies.
One 40kW 3-level converter and one 5kW 5-level converter has been designed and built. Experimental verification of the analytical and simulated results is shown.
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Cavanaugh, Curtis. "AN ADAPTIVE ELECTRONIC INTERFACE FOR GAS SENSORS." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-20020108-121219.
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CAVANAUGH, CURTIS C. An Adaptive Electronic Interface for Gas Sensors (Under the direction of H. Troy Nagle).This thesis focuses on the development of an adaptive electronic interface for gas sensors that are used in the NC State electronic nose. We present an adaptive electronic interface that allows for the accurate mapping of the sensor?s voltage output to sensor resistance profiles. The adaptive interface uses a linearized Wheatstone bridge in a constant current configuration. The balancing of the bridge and the adjustment of the subsequent gain stage is performed using programmable variable resistors. The programmable resistors are controlled by a LabVIEW® program. The same control program also determines and records all the resistor values in the interface circuit. The resistance of each sensor is accurately computed by LabVIEW® using the interface-circuit, resistor values, and the voltage output of the circuit. Compensating for sensor drift can be done in LabVIEW® by adjusting the programmable resistor values so that a zero-voltage output is produced during the reference cycle. By doing this zero adjustment between each ?sniff? of an odorant, the baseline drift can be minimized.A single channel of the adaptive electronic interface has been designed and tested. The interface can be calibrated so that it is 99% accurate when performing sensor resistance measurements.A new conducting polymer sensor chamber has also been designed and tested. The new radial flow sensor chamber was minimizes the dead volume in the chamber and also deliver the odorant to each sensor at the same time. Two operating modes were compared: continuous-flow and sniff-and-hold. Both modes gave good classification performance while testing four different coffee samples. Experimental testing indicates that sensor response is highly correlated with the sample flow rate. Future work to more fully characterize this correlation is recommended.
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Du, Toit J. A. (Jacques Andre). "Development and analysis of a distributed control strategy for power electronic converters." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52761.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: The dissertation presents an alternative approach to the control of power electronic converters. The conventional approach is to use a centralized controller with one or more measurement systems providing feedback. As converters become larger, in both power rating and complexity, a number of drawbacks to this approach emerge. The number of physical data paths increases and voltage isolation becomes a problem. This has an adverse effect on the manufacturability as well as the reliable operation of the system as a whole. An alternative is to use a distributed control approach, where a number of smaller integrated control and measurement units are used. These units communicate with the central controller via a serial daisy-chain communications link. The dissertation investigates the design of such a controller as well as the application of distributed control in a number of emerging converter topologies. It was shown that centralized control has its limitations in modem power electronics in terms of reliability, maintainability and manufacturability. A feasible distributed control strategy was proposed and implemented and the operation was verified in an experimental converter system.
AFRIKAANSE OPSOMMING: Die proefskrif ondersoek 'n alternatiewe manier om drywings omsetters te beheer. Huidiglik word die meerderheid van omsetters beheer vanaf 'n sentrale beheereenheid, wat dan stelsel data versamel vanaf een of meer meetstelsels. Soos die drywingsvermoë van die omsetters toeneem, raak spannings isolasie en die aantal beheerseine 'n probleem, wat nadelig is vir die betroubaarheid en vervaardigbaarheid van die stelsel. As 'n alternatief, kan 'n aantal kleiner beheereenhede en meetstelsels gebruik word. Die beheerders kommunikeer met mekaar, sowel as die hoof stelselbeheerder deur middel van 'n optiese vesel netwerk, verbind in 'n ring struktuur. Die proefskrif ondersoek die ontwerp van die beheerder en die toepassing van gedesentraliseerde beheer in 'n aantal nuwe omsetter topologië. Die studie toon dat sentrale beheer problematies kan raak soos die omsetters meer kompleks raak. Die studie bewys dat 'n stelsel suksesvol bedryf kan word deur gebruik te maak van gedesentraliseerde beheer deur dit in 'n praktiese opstelling toe te pas.
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Valsalan, Rincy. "Electronic Water Heater." Thesis, Högskolan i Halmstad, Halmstad Embedded and Intelligent Systems Research (EIS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-37922.
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The main aim of my project is to develop a hardware implementation of the electronic waterheater by choosing different components and minimize the errors in the same. I have consideredseveral options depending on the availability of components, cost, reliability, implementation,financial budget, specification and thinking about the professional technical skills required. Inthis project I designed and implemented, an AVR micro controller based water temperaturemeasurement system using Atmega328p microcontroller.The idea of the project came from a company called Relek production AB, Sweden and theydevelop and supply electrical equipment for heating: such as electric boilers, under floor heatingboilers, IR heaters, emergency power plants, power monitors, etc. Now they want to develop anew version of electronic water heater and according to their specification.The microcontroller (Atmega328p) based temperature control system is used in this project forproviding better functioning of the system and will also serve the following purposes.1) As there will be less usage of energy as it is more energy efficient.2) The microcontroller along with temperature sensor decides when the heater shouldturn on/off.With this project I have designed the schematic diagram by using Eagle Autodesk PCB CADprogram. The seven-segment display is used in this project to show the current temperature. Atemperature sensor (LM35) is used in this project to sense the temperature and give thesemeasured values to the microcontroller. The temperature measurement and heater control areprocessed using C++ program.I have connected the circuit as per the schematic diagram and programed the microcontroller,interfacing all the major components like 7 segment display, temperature sensor, 2 pushbuttons(for manually incrementing and decrementing the set point in the program), and optoisolator (tosense the output from microcontroller and control the heater through thyristor).
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Ahmadi, Teshnizi Amir Pouya, Marcus Hellström, Tom Bärnheim, and Hassan Soltani. "IoT Air Quality Sensor Array : Master's Programme in Electrical Engineering." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448142.
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Neff, Clayton. "Analysis of Printed Electronic Adhesion, Electrical, Mechanical, and Thermal Performance for Resilient Hybrid Electronics." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7551.
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Today’s state of the art additive manufacturing (AM) systems have the ability to fabricate multi-material devices with novel capabilities that were previously constrained by traditional manufacturing. AM machines fuse or deposit material in an additive fashion only where necessary, thus unlocking advantages of mass customization, no part-specific tooling, near arbitrary geometric complexity, and reduced lead times and cost. The combination of conductive ink micro-dispensing AM process with hybrid manufacturing processes including: laser machining, CNC machining, and pick & place enables the fabrication of printed electronics. Printed electronics exploit the integration of AM with hybrid processes and allow embedded and/or conformal electronics systems to be fabricated, which overcomes previously limited multi-functionality, decreases the form factor, and enhances performance. However, AM processes are still emerging technologies and lack qualification and standardization, which limits widespread application, especially in harsh environments (i.e. defense and industrial sectors).
This dissertation explores three topics of electronics integration into AM that address the path toward qualification and standardization to evaluate the performance and repeatable fabrication of printed electronics for resilience when subjected to harsh environments. These topics include: (1) the effect of smoothing processes to improve the as-printed surface finish of AM components with mechanical and electrical characterization—which highlights the lack of qualification and standardization within AM printed electronics and paves the way for the remaining topics of the dissertation, (2) harsh environmental testing (i.e. mechanical shock, thermal cycling, die shear strength) and initiation of a foundation for qualification of printed electronic components to demonstrate survivability in harsh environments, and (3) the development of standardized methods to evaluate the adhesion of conductive inks while also analyzing the effect of surface treatments on the adhesive failure mode of conductive inks.
The first topic of this dissertation addresses the as-printed surface roughness from individually fusing lines in AM extrusion processes that create semi-continuous components. In this work, the impact of surface smoothing on mechanical properties and electrical performance was measured. For the mechanical study, surface roughness was decreased with vapor smoothing by 70% while maintaining dimensional accuracy and increasing the hermetic seal to overcome the inherent porosity. However, there was little impact on the mechanical properties. For the electrical study, a vapor smoothing and a thermal smoothing process reduced the surface roughness of the surfaces of extruded substrates by 90% and 80% while also reducing measured dissipative losses up to 24% and 40% at 7 GHz, respectively.
The second topic of this dissertation addresses the survivability of printed electronic components under harsh environmental conditions by adapting test methods and conducting preliminary evaluation of multi-material AM components for initializing qualification procedures. A few of the material sets show resilience to high G impacts up to 20,000 G’s and thermal cycling in extreme temperatures (-55 to 125ºC). It was also found that coefficient of thermal expansion matching is an important consideration for multi-material printed electronics and adhesion of the conductive ink is a prerequisite for antenna survivability in harsh environments.
The final topic of this dissertation addresses the development of semi-quantitative and quantitative measurements for standardizing adhesion testing of conductive inks while also evaluating the effect of surface treatments. Without standard adhesion measurements of conductive inks, comparisons between materials or references to application requirements cannot be determined and limit the adoption of printed electronics. The semi-quantitative method evolved from manual cross-hatch scratch testing by designing, printing, and testing a semi-automated tool, which was coined scratch adhesion tester (SAT). By cross-hatch scratch testing with a semi-automated device, the SAT bypasses the operator-to-operator variance and allows more repeatable and finer analysis/comparison across labs. Alternatively, single lap shear testing permits quantitative adhesion measurements by providing a numerical value of the nominal interfacial shear strength of a coating upon testing while also showing surface treatments can improve adhesion and alter the adhesive (i.e. the delamination) failure mode of conductive inks.
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Wu, Yudong. "Simulation of graphene electronic devices." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1554/.
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Since the publication of research in the mid-1980s describing the formation of freeform graphene there has been an enormous growth in interest in the material. Graphene is of interest to the semiconductor industry because of the high electron mobility exhibited by the material and, as it is planar, it is compatible with silicon technology. When patterned into nanoribbons graphene can be made into regions that are semiconducting or conducting and even into entire circuits. Graphene nanoribbons can also be used to form the channel of a MOSFET. This thesis describes numerical simulations undertaken on devices formed from graphene. The energy band structure of graphene and graphene nanoribbons is obtained using nearest-neighbour and third nearest-neighbour interactions within a tight binding model. A comparison of the current-voltage characteristics of MOS structures formed on graphene nanoribbons and carbon nanotubes suggests that the nanoribbon devices may be better for switching applications. Conductivities of graphene nanoribbons and junctions formed from them were obtained using a nonequilibrium Green’s function formulation. The effects of defects and strain on these systems were also studied using this technique. Advancements were made when the self-energies used within the nonequilibrium Green’s function were obtained from an iterative scheme including third nearestneighbour interactions. An important result of this work is that accurate simulations of graphene based devices should include third nearest-neighbour interactions within the tight binding model of the energy band structure.
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yang, xiao yang. "Electronic Properties of Methyl-Terminated Germanane and Hydrogen-terminatedGermanane." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502899689885614.
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Owadally, Muhammud Asaad. "Robust electronic circuit design using evolutionary and Taguchi methods." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/21761.
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Bibliography: pages 80-81.In engineering, there is a wide range of applications where genetic optimizers are used. Two genetic optimizers used in this thesis namely, Population Based Incremental Learning ( PBIL ) and Cross generational selection Heterogeneous crossover Cataclysmic mutation ( CHC ), are tested on a series of circuit problems to fmd if robust electronic circuits can be built from evolutionary methods. The evolutionary algorithms were used to search the space of discrete component values from a range of manufactured preferred values to obtain robust electronic circuits. Parasitic effects were also modelled in the simulation to provide for a more realistic circuit.
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Al, Kzair Christian, Altin Januzi, and Andreas Blom. "Understanding the fundamentals of CPU architecture : Bachelor project in Electrical engineering." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353427.
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Understanding how a computer or rather a CPU works can be a bit tricky and hard to understand. We live today in a society full of computers and there are many who do not understand how a CPU works. This project is aimed to understand how a CPU works and the architecture behind it. For this it is demonstrated the fundamental theory behind it but also a practical computer that has been built from scratch. This computer can demonstrate the theory behind how the CPU works and also how it communicates. This computer is 8-bit which has it limitations but can show the fundamental theory behind how computers work.
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Geerdts, C. D. "SOFTWIRE : an interactive, computer-based system for enhancing learning in electrical engineering using simulation." Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/8364.
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The aim of the dissertation is to explore a method of enhancing learning in the Electrical Engineering curriculum, which effectively exploits the computer. The different modes used in computer-based learning are discussed and compared, and the conclusion reached that simulation provides the best basis for a learning enhancement system. It has the ability to facilitate demonstration of basic concepts, learning of estimation, modular system design, and the use of models in engineering, and group work. It is a useful complement to laboratory work. It also enhances motivation and interest. A system is motivated loosely based on the architecture of the analogue computer, but tailored for an educational environment by being interactive, simple-to-use, adaptable and extendable by the tutor, and carrying a wide variety of educationally valuable inbuilt functions. The system proposed, SOFTWIRE, consists of a software package, a hardware laboratory interface as well as a broad approach to strategy, based on basic Learning Theory. Design issues relating to the hardware, software, and implementation of pedagogic strategy are discussed. Some examples of the use of the system are given. Thus both the broad and specific approach are covered. Some of the modes of useage discussed are demonstrations, design problems involving the construction of simulations in SOFTWIRE's language, interacting with simulations to experience them and to see the effects of parameter and structure changes, and learning about modelling and its relation to the real world. Evaluation is discussed, especially in relation to SOFTWIRE. Conclusions are drawn, and suggestions made about future development of the SOFTWIRE system, as well as relevant trends in computer education.
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Barto, Taylor. "Design and Control of Electronic Motor Drives for Regenerative Robotics." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu150396313057516.
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De, Wit Leon. "Flicker mitigation in industrial systems." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1994.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis investigates the compensation of voltage flicker in an industrial environment. Industrial loads draw progressively less sinusoidal currents. These currents cause non-sinusoidal voltage drop over the line impedance, causing a distorted line voltage. The light output of incandescent electric lighting systems is quadratically proportional to the line voltage, and thus variations in the line voltage cause irritating variations in the output of such systems. Two tools to analyse flicker problems are developed: A USB data logger is built to log measured waveforms to computer hard disk. These data are analysed using a MATLAB implementation of the IEC-specified flicker meter. A converter-based flicker compensator is found to be the only compensator capable of compensating general flicker loads. Such a compensator is developed using the synchronous reference frame filtering technique. Several aspects of the compensator are dealt with in detail including selection of a current control strategy, calculation and implementation of the converter duty cycles and compensation of the various non-idealities in such a controller. Full compensation is contrasted to reactive compensation – the second option being less expensive but also less effective in the compensation of certain loads. The effectiveness of reactive compensation is found to be dependent not only on the type of load, but also on the type of line feeding the flicker load. Three industrial flicker loads are measured and analysed: a three-phase welder, a sawmill and a rock crusher. These loads are simulated, and the compensation proposed confirmed via these simulations. The compensation of the three-phase welder is tested using a hardware scale model. This verified the operation of the proposed flicker compensator in practice.
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Shang, Alain. "Transceiver arrays for optically interconnected electronic systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ37024.pdf.
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Mahajan, Nikhil R. "System Protection for Power Electronic Building Block Based DC Distribution Systems." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-12052004-233822/.
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The purpose of this research has been to develop an agent based protection and reconfiguration scheme for power electronic building block based (PEBB) DC distribution systems. One of the foremost applications would be in the new zonal DC distribution on naval ships. The research involves the design of an agent based protection scheme which uses the PEBBs for current limiting and circuit breaking purposes. Considerations are given to reduce the system downtime under fault conditions, allow proper coordination and provide backup protection. The research also involves the design of a reconfiguration management scheme based on collaborative agents. The collaboration ensures that the reconfiguration is achieved at a global level, enhancing the system survivability under the conditions of multiple faults and damages. The coordination ensures that only the faulted part of the system is isolated and the reconfiguration makes sure that the power to the healthy part of the system is supplied continuously. The reconfiguration management also performs load shedding if the generation does not meet the load demand of the reconfigured system due to a fault or damage in the generator.
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Wang, Han Ph D. Massachusetts Institute of Technology. "Two-dimensional materials for electronic applications." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84899.
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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 205-232).
The successful isolation of graphene in 2004 has attracted great interest to search for potential applications of this unique material and other members of the two-dimensional materials family in electronics, optoelectronics and their interface with the biological systems. At this early stage of 2D materials research, many opportunities and challenges co-exist in this area. This thesis addresses the following issues which are crucial for 2D electronics to be successful, focusing on developing graphene for RF electronics and MoS2 for digital applications: (1) Development of some of the first graphene-based devices for high frequency applications; (2) Development of compact physical models for graphene transistors; and (3) Understanding the carrier transit delays in graphene transistors. In addition, this thesis proposes and experimentally demonstrates a completely new concept - Ambipolar Electronics - to take advantage of the unique properties of graphene for RF applications. Based on this new concept, a family of novel applications are developed that can significantly simplify the design of many fundamental building blocks in RF electronics, such as frequency multipliers, mixers and binary phase shift keying devices. In the last part of the thesis, the applications of other emerging 2D materials from the transition metal dichalcogenides family, such as molybdenum disulfide (MoS₂), is also explored for potential application in digital electronics, especially as a new material option for high performance flexible electronics. The future opportunities and potential challenges for the applications of the 2D materials family are also discussed.
by Han Wang.
Ph.D.
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Liburd, Soyini (Soyini Denise) 1980. "An N-version electronic voting system." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28441.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 103-109).
The ballot battles of the 2000 US Presidential Election clearly indicate that existing voting technologies and processes are not sufficient to guarantee that every eligible voter is granted their right to vote and implicitly to have that vote counted, as per the fifteenth, nineteenth, twenty fourth and twenty sixth amendments to the US constitution [1-3]. Developing a voting system that is secure, correct, reliable and trustworthy is a significant challenge to current technology [3, 4]. The Secure Architecture for Voting Electronically (SAVE) demonstrates that N-version programming increases the reliability and security of its systems, and can be used to increase the trustworthiness of systems. Further, SAVE demonstrates how a viable practical approach to voting can be created using N-version programming. SAVE represents a significant contribution to voting technology research because of its design, and also because it demonstrates the benefits of N-version programming and introduces these benefits to the field of voting technology.
by Soyini D. Liburd.
M.Eng.
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Cohen, Sharon B. "Auditing technology for electronic voting machines." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33119.
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Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (leaf 63).
Direct Recording Electronic (DRE) voting machine security has been a significant topic of contention ever since Diebold voting machine code turned up on a public Internet site in 2003 and computer scientists at Johns Hopkins University declared the machine "unsuitable for use in a general election." Since then, many people from computer scientists to politicians have begun to insist that DREs be equipped with a paper trail. A paper trail provides a paper printout for the voter to approve at the end of each voting session. Although there have been strong political efforts to place paper trails on DRE machines, there have not been any scientific studies to indicate that paper trails are effective audits. This work describes a user study done to compare paper trails to audio audits, a new proposal for DRE auditing. Participants in the study completed four elections on a voting machine with a paper trail and four elections on a machine with an audio trail. There were purposeful mistakes inserted into the audits on some of the machines. Results from the study indicated that participants were able to find almost 10 times as many errors in the audio audit then they were able to find in the paper trail. Voters' attitudes towards the paper audit were extremely apathetic, and voters did not spend much time reviewing their paper record. When asked which type of audit voters would prefer for their own county elections, almost all voters preferred the VVPAT. These results indicate that newer alternative audit technology holds great promise in delivering a safe and accurate audit and further that paper trails have some significant design obstacles that need to be overcome before they will be effective audits.
by Sharon B. Cohen.
M.Eng.and S.B.
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Koen, Douglas B. (Douglas Branch). "Automated restructuring of an electronic newspaper." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34337.
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Rubin, Jeremy Lloyd. "Decentralized utilization incentives in electronic cash." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105964.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 109-113).
Many mechanisms exist in centralized systems that incentivize resource utilization. For example, central governments use inflation for many reasons, but a common justification for inflation in practice is as a means to incentivize resource utilization. Incentives to utilize resource may stimulate economic growth. However, the asymmetry of economic control and potential abuses of power implicit in centralized systems may be undesirable. An electronic cash design may be able to create resource utilization incentives via decentralized mechanisms. Decentralized mechanisms may be economically sustainable without centralized and potentially coercive forces. We propose Hourglass, a novel electronic cash design that provides a decentralized mechanism to encourage utilization via expiration dates. Constructed in this way, decentralized utilization incentives may have less potential for coercive abuses than more centralized methods, but may be similarly effective in their ability to incentivize utilization. We present the Hourglass system at multiple levels of detail: a design overview, a minimal kernel framework, a series of descriptive refinements, and a concrete implementation as a fork of Bitcoin (a popular electronic cash protocol in common use). We also present several potential applications of Hourglass, such as renewable resource markets, spectrum allocation, stock issuance, and currency.
by Jeremy Lloyd Rubin.
M. Eng.
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Bridge, David Richard. "Aspects of electronic device packaging." Thesis, University of Warwick, 1986. http://wrap.warwick.ac.uk/58807/.
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For this work cordierite has been investigated as a possible substitute substrate material for alumina, with particular emphasis on its role in multilayer device packaging. By limiting the processing temperatures to below 1000oC, copper could be used as the conductor material. Milled glass powder was made into thin sheet form by a doctor blading technique and, once dried, the copper screen printed on top. After lamination and firing, the conductor was completely encapsulated by the cordierite matrix. Copper diffusion occ~red with metallic copper precipitating out although a small denuded zone was evident around the periphery of the conductor. This was due to compositional changes occurring there. Experiment showed that the effects of glass particle shape, average size and size distribution lead to deviation in the shrinking of compacts from the theoretical sintering curves. An unstable ~ phase was the first to appear on the glass particle surfaces although another, unidentifiable phase, was also found to exist during the very early stages of crystallization. This was followed shortly after by bulk crystallization of ~ cordierite in the remaining glass, possibly being aided by a prior phase separation. Further heat treatment lead to the transformation to a cordie rite and the formation of enstatite, the exact transformation temperature depending upon the minor oxide additives in the glass. At temperatures above ~10500C protoenstatite formed and lead to a general degradation in material properties. The benefit from having a cordie rite as the principal phase is a low dielectric constant (5.35) and loss angle (5 x 10-4), reasonable strength (130 MPa) and high resistivity (~1015 Qcm). This makes it a suitable replacement for alumina although its low thermal conductivity (~2 Wm-lK-l) is a drawback. By adjusting the MgO/A1203 ratio, the material could be expansion matched to that of silicon.
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Mitchley, Ryan. "Evaluation of selected subspace tracking algorithms for direction finding." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/442.
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Galbraith, A. S. G. "Estimation of Synchronous Generator Parameters using Time-domain Responses." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1663.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005.Power system stability simulations are of growing importance for studying the operational integrity of modern power systems, especially in developing economies where generating and transmission capacity lead the demand by relatively small margins. The relevant model topologies, i.e. for synchronous generators, automatic voltage regulators (AVR) and governor control systems, and the simulation software tools are well established. The MATLAB® Power System Blockset provides engineers with a versatile power system stability simulation environment, particularly where the focus is on individual units or small systems. In comparison with dedicated power system simulation tools such as DIgSILENT®, the MATLAB® environment features a superior set of advanced data processing and data analysis features. This includes features such as optimisation and parameter estimation functions. The main aim of this project is to make use of the MATLAB® package in a bid to test an alternative platform with which to estimate the synchronous machine parameters. Conditioning of field data can delay the process considerably, thus the secondary task of this thesis is to solve this issue by ensuring that only one platform is needed for the entire process starting in the field and ending in the modelling and parameter estimation environment within MATLAB®. In closing, the following points summarise the essential aims of this project: • An application using MATLAB® Script must be created that is responsible for importing and processing the data, so it is suitable for analysis purposes. The processing could include cropping, scaling and filtering of data. • Once the data has been imported it must be used with appropriate models to estimate for machine parameters. This will require the use of the Power Systems Blockset. The actual estimation process also requires the creation of an effective cost function, thus a number of different scenarios will have to be investigated before a solution can be found.
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Sumsurooah, Sharmila. "Robust stability analysis of power electronic systems." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/37829/.
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Power electronics is the enabling technology that can put transportation on a more sustainable pathway. The key problem with power electronic (PE) systems is that they are prone to instability. Classical techniques are insufficient at assessing the stability of these systems, as they do not take into account the uncertain nature of physical systems. This thesis presents the structured singular value (SSV) method as an effective, reliable and robust stability analysis approach that justifiably incorporates uncertainties which are inherently present in physical systems. Although the SSV approach has numerous benefits, it has a few drawbacks that tend to make it hard to apply. Its theoretical framework remains complex. The practical approaches to applying the SSV method to PE systems seem lacking in the literature. The SSV approach is generally applied to linear system models while most systems are non-linear in nature. This thesis demonstrates the applicability of the SSV method to PE systems, by addressing these limitations. The work first brings deeper and clearer insights into key concepts of SSV theory. It demonstrates the significance and usefulness of the robust stability measure (SSV) in the space of multiple parametric uncertainties, through the concept of the hypercube. Secondly, it presents several practical approaches to applying the SSV method to PE systems. Finally, it develops a modelling methodology that converts a non-linear system to an equivalent linear model, suited for SSV analysis. The findings are supported by simulation and experimental results of the buck converter, permanent magnet machine drive, ideal constant power load and resistance-inductance-capacitance systems. This thesis provides the design engineer with some crucial theoretical and practical tools for applying the SSV approach to both linear and non-linear models of PE systems, while showing how to reap the full benefits of the method. It is the author's belief that the SSV method can be used as widely as classical methods, and to great effect.
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Barrios, Andres J. "Nonlinear quantum transport in low-dimensional electronic devices." FIU Digital Commons, 2002. http://digitalcommons.fiu.edu/etd/1414.
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The study of transport processes in low-dimensional semiconductors requires a rigorous quantum mechanical treatment. However, a full-fledged quantum transport theory of electrons (or holes) in semiconductors of small scale, applicable in the presence of external fields of arbitrary strength, is still not available. In the literature, different approaches have been proposed, including: (a) the semiclassical Boltzmann equation, (b) perturbation theory based on Keldysh's Green functions, and (c) the Quantum Boltzmann Equation (QBE), previously derived by Van Vliet and coworkers, applicable in the realm of Kubo's Linear Response Theory (LRT).
In the present work, we follow the method originally proposed by Van Vliet in LRT. The Hamiltonian in this approach is of the form: H = H°(E, B) + λV, where H0 contains the externally applied fields, and λV includes many-body interactions. This Hamiltonian differs from the LRT Hamiltonian, H = H° - AF(t) + λV, which contains the external field in the field-response part, -AF(t). For the nonlinear problem, the eigenfunctions of the system Hamiltonian, H°(E, B) , include the external fields without any limitation on strength.
In Part A of this dissertation, both the diagonal and nondiagonal Master equations are obtained after applying projection operators to the von Neumann equation for the density operator in the interaction picture, and taking the Van Hove limit, (λ → 0 , t → ∞ , so that (λ2 t)n remains finite). Similarly, the many-body current operator J is obtained from the Heisenberg equation of motion.
In Part B, the Quantum Boltzmann Equation is obtained in the occupation-number representation for an electron gas, interacting with phonons or impurities. On the one-body level, the current operator obtained in Part A leads to the Generalized Calecki current for electric and magnetic fields of arbitrary strength. Furthermore, in this part, the LRT results for the current and conductance are recovered in the limit of small electric fields.
In Part C, we apply the above results to the study of both linear and nonlinear longitudinal magneto-conductance in quasi one-dimensional quantum wires (1D QW). We have thus been able to quantitatively explain the experimental results, recently published by C. Brick, et al., on these novel frontier-type devices.
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Nie, Xin 1969. "Graphic user interface for power electronic research facility." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20511.
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This thesis synthesizes the development of a graphical user interface for multi-converter research facility using Visual C++ 4.0 and Microsoft Foundation Class library on Windows95 platform. The multi-converter research facility is used in flexible ac transmission system control. The design of the user interface follows the user-centered design philosophy. The main idea of the user-centered design is to produce the user interface for the convenience and efficiency of the user rather than the software designer.The user interface manages the data transfer between the hardware and user and allows the user to change the hardware settings via interactive dialogs. It also displays the current parameters running on the hardware, thus provides the user with a more convenient and efficient way of monitor the performance of the multi-converter research facility.
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Germain, François. "A nonlinear analysis framework for electronic synthesizer effects." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104845.
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This thesis presents a theoretical and experimental study of the nonlinear behaviour of analog synthesizers' effects. The goal of this thesis is to evaluate and complete current research on nonlinear system modelling, both in and out of the field of music technology. The cases of single-input and multiple-input effects are considered.We first present an electronic analysis of the circuits of common examples of analog effects such as Moog's lowpass filter and Bode's ring modulator, extracting the equations of each system. We then discuss the results of experiments made on these systems in order to extract qualitative information about the distortion found in the system input-output relationship.Secondly, we look at the literature for methods used to model single-input nonlinear systems, and we investigate the opportunities to extend these techniques to multi-input systems. We focus on two different modelling approaches. The black-box approach seeks to model the input-output transfer function of the system as closely as possible without any particular assumption on the system. The circuit modelling approach uses the knowledge of electronic component behaviour to extract a transfer function from the known circuit of the system. The results of both approaches are compared to our experiments in order to evaluate their accuracy, identify flaws and, when possible, suggest potential improvements of the methods.Cette thèse présente une étude théorique et expérimentale du comportement nonlinéaire des effets de synthétiseurs analogiques. Elle vise à évaluer et compléter les recherches actuelles sur la modélisation des systèmes non-linéaires, à la fois dans le domaine de la technologie de la musique et en dehors. Les cas des effets à une ou plusieurs entrées sont examinés. Pour ce faire, nous présentons d'abord une analyse électronique des circuits de plusieurs exemples usuels d'effets analogiques tels que le filtre passe-bas de Moog ou le modulateur en anneau de Bode. Les équations régissant chaque système en sont dérivées. Nous discutons ensuite le résultat d'expériences menées sur ces systèmes pour extraire une caractérisation qualitative de la distorsion présente dans le rapport entrée-sortie du système. Dans un second temps, nous examinons les méthodes de modélisation des systèmes non-linéaires à une entrée trouvées dans la littérature, et nous explorons les possibilités d'extension de ces techniques aux systèmes à plusieurs entrées. Deux approches de modélisation sont abordées. L'approche boîte noire vise à modéliser la fonction de transfert entrée-sortie du système aussi fidèlement que possible sans hypothèse sur la structure du système. L'approche de la modélisation du circuit utilise quant à elle la connaissance du comportement des composants électroniques pour extraire une fonction de transfert à partir du circuit (connu) du système. Les résultats associés aux deux approches sont comparés à nos expériences pour évaluer leur performance, et identifier des lacunes et, quand c'est possible, des opportunités d'amélioration de ces méthodes.
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Escobar-Mejia, Andres. "Indirect Matrix Converter as Standard Power Electronic Interface." Thesis, University of Arkansas, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3667722.
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The increase in the penetration levels of distributed generation in the modern power grid and its importance in future energy systems have accelerated the interest of developing new power electronic interfaces for the energy conversion process. The feasibility of applying the indirect matrix converter as the standard power electronic interface for applications with power ratings from several kW to few MW is addressed in this dissertation. Special attention is given to those applications where space dominates the power electronic requirements. The main motivation for using the indirect matrix converter is that eliminates the energy storage component in the way of a dc-link capacitor for the energy conversion process. This contributes to reduce size and weight, and potentially, increase reliability of the power electronic interface. Two main new contributions are presented. First, a new power electronic interface that allows the connection of two ac power grids through a medium- or high-voltage dc system is proposed. The new topology contemplates the use of two high-voltage dc-link converters based on the modular multilevel converter, two indirect matrix converters and two medium-frequency transformers. Second, a new sensorless control technique working in the d – q reference is developed. The controller is used to interface a distributed generation unit to the power grid when the indirect matrix converter is used as the power electronic interface. The design and performance of the proposed power electronic interface is validated through time-domain simulations and a laboratory prototype is built to experimentally validate the sensorless controller.
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Jiang, Yang. "Clock-jitter insensitive circuit techniques in continuous-time sigma-delta modulators." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590641.
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Risemark, Eriksson Martin. "Environmental stress of electrical machine winding insulation." Thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326711.
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The conducting winding of an electrical machine is insulated in order to prevent any short circuits to occur within the machine. This insulation is during its lifetime exposed to several environmental stresses and therefore plays an important role in the life length of the machine. Accelerated stress tests are used to investigate what design and material is most suitable for a good endurance of a product. In this master thesis, new accelerated test methods for the insulation system in an electrical machine are developed and evaluated. The study resulted in four stress tests that simulate the thermal stress, the thermomechanical stress and the ambient stress from direct oil cooling. Three diagnosis tests and a material analysis were used in order to evaluate how these accelerated stress test methods affected the insulation. The diagnosis tests showed no clear sign of deterioration of the insulation in terms of change in electrical characteristics. However, the material analysis indicated deterioration of the insulation, such as cracks and oxidation of the material. These changes show that the test methods are capable to affect the insulation, but will need more time to cause a breakdown, since a stator of this kind is expected to have a very long life length. Therefore, in future work on this topic, these test methods should continue for a longer time and it would likely be interesting to look into other diagnosis tests.
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Voigt, Dewald. "Computational investigation of a crossed slot cavity-backed array antenna." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2659.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis investigates a computational model of an electronically steered antenna array. It focuses on a simple element comprising an S-shaped, crossed, cylindrical cavity-backed slot antenna. An unusual aspect of the element is the addition of a top hat, which contributes to the low scanning ability of the array. The objective was to confirm this contribution of the top hat. During the investigation, the computation code Feko was validated for slot analysis through consideration of the basic properties of a dipole and slot and how they related to each other. Various alternative models were evaluated, before a final accurate model was modelled in Feko, to find possible equivalent models. The final model, which implemented the use of Feko as release 5, was the only one that achieved successful results. The results showed that the top hat does play an important role in the steering of the beam. The mechanism through which this occurs was identified. The results that where obtained indicated that there may be more effective elements than the cylindrical element and the identification of this is proposed as a field for further study.
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Varzandeh, Navid. "New immobilizer concept based on Scania’s electrical platform." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-29180.
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Immobilizers are security systems that are set up and installed in modern vehicles in order to prevent thieves from starting the vehicles. The idea is that if any wrong keys are used to start the vehicle, the immobilizer detects the wrong key and start the immobilization procedure to stop the vehicle from turning on. The vehicle ignition key (key transponder or key fob) is one of the important components in an immobilizer system. An ignition key in an immobilizer system has a Radio Frequency Identification Device (RFID) chip inside it. This RFID chip holds a specific encryption algorithm and particular number of bits (encryption key bits) in itself. Using the encryption algorithm and encryption key bits, RFID chip inside the key authenticates and identifies itself as the right key to the immobilizer system in order to disable the immobilization procedure and start the vehicle. However, there are two ways thieves can disable the immobilization procedure and start the vehicle. The first approach is by discovering the specific encryption algorithm and key bits in the right key transponder (RFID) and using them to duplicate the correct RFID chip to disable the immobilization procedure and start the vehicle. The second approach is by exploiting the vulnerabilities and weaknesses in vehicle security network (CAN bus) to bypass the immobilizer and manipulate the immobilization procedure to start the vehicle. Scania vehicles are not using the most secure RFID and immobilization procedures, hence they are vulnerable to two vehicle theft approaches above. Therefore in this thesis project, I have done research and investigation on Scania vehicles key transponder (RFID) and analyzed their immobilization procedures in order to identify the roots and origins of vulnerabilities in Scania RFID and immobilization procedures. As the first result of this thesis work, I have found and proposed an RFID chip having one of the strongest encryption algorithms and proper number of encryption key bits for all Scania vehicles. As the second result of this thesis project, I have proposed and introduced two new individual immobilization procedures exclusively for Scania hybrid and electrical vehicles. Both proposed RFID (encryption algorithm) and immobilization procedures will be implemented in Scania vehicles in near future and will increase the security of Scania immobilizers significantly.
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Yao, James Chung-Yo. "Leaders for Manufacturing Program electronic mail network." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/61055.
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Bagwell, Philip F. (Philip Frederick). "Quantum mechanical transport in submicron electronic devices." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/44264.
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Zhang, Xu Ph D. Massachusetts Institute of Technology. "Two-dimensional crystals : spectroscopy and electronic applications." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112036.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 159-177).
The success in creating atomically thin and mechanically robust two-dimensional (2D) crystals, starting with graphene, has unveiled new possibilities for next generation of ultrafast and ubiquitous electronics. One critical distinction between 2D crystals and 3D crystals is that 2D crystals are all-surface materials. Therefore, it is essential to understand how 2D materials interact with their environments and how this interaction impacts their electronic properties. From a practical perspective, it also provides us with a unique tool to tailor the electronic properties of 2D materials through surface functionalization. In the first half of this thesis, a suite of X-ray techniques is used to investigate how the surface functionalizing dopants will impact the electronic and chemical states of graphene. Based on this study, we develop an effective and non-invasive doping method for graphene through plasma-based chlorination. In order to make system-level 2D electronics successful, a flexible and ubiquitous energy harvesting solution is indispensable. Therefore, the second part of this thesis is dedicated to the development of a MoS₂ 2H-1T phase heterojunction-based GHz flexible rectifier as an enabling component for wireless energy harvester. It is the first flexible rectifier operating up to the X-band and it covers most of the unlicensed industrial, scientific and medical (ISM) radio band, including the Wi-Fi channels. By integrating this rectifier with an antenna, the MoS₂-enabled rectenna successfully demonstrates direct energy harvesting of electromagnetic (EM) radiation in the Wi-Fi band and lights up a commercial light-emitting diode (LED) with zero external bias (battery-free). Moreover, our MoS₂ rectifier also realizes successful frequency conversion as a mixer beyond 10 GHz on flexible substrates. This work provides a universal energy harvesting building block that can be integrated with various wearable electronic systems and paves the way towards using the existing Wi-Fi infrastructure as an energy hotspot for wireless charging.
by Xu Zhang.
Ph. D.
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Tassoudji, Mohammad Ali. "Electromagnetic interference in electronic circuits and systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35392.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (p. 191-198).
by Mohammad Ali Tassoudji.
Ph.D.
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Moy, Melanie 1979. "A secure architecture for electronic check processing." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28446.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (leaves 49-51).
Traditional paper checks have been estimated to cost US banks over $2.1 billion dollars a year to process [1]. Much of the cost is due to the time and fees related to human intervention and the physical transport of a check. Gupta and Palacios [15] have defined a web-based check processing mechanism; this paper extends the framework they have developed and defines a cryptographic protocol for the transmission of digital checks using cryptographic building blocks like public key encryption and digital signatures.
by Melanie Moy.
M.Eng.
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Nickel, Jacob. "Development of an electronic lung airway atlas." Thesis, University of Iowa, 2008. http://ir.uiowa.edu/etd/14.
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Enohnyaket, Mathias. "Electromagnetic characterization of power electronic systems." Doctoral thesis, Luleå tekniska universitet, EISLAB, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17800.
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Propelled by increased global awareness and demand for clean energy systems, there is a growing trend in transportation, utility, industrial, and residential applications towards the utilisation of power electronic systems with enhanced power ow controllability and eciency. Examples of power electronics applications include terminal converters in high-voltage direct Current (HVDC) transmission; exible AC transmission systems (FACTS); and converters to interface alternative energy systems such as wind turbines to the grid, variable-speed motor drives in pump systems, vehicular propulsion systems, air-conditioners, and refrigerators.The basic functionality of power electronic components is achieved by switching high voltages and currents. Recent advancements in semiconductor technology have significantly improved the current and voltage handling capabilities and the switching frequencies of power electronic devices. However, this rapid switching of high currents and voltages in turn generates electromagnetic disturbances that could distort the functionality of the power electronic equipment and other devices in the vicinity. Electromagnetic compatibility (EMC) regulations and functionality requirements impose restrictions on the design of power electronic systems. To design robust power electronic systems, a thorough understanding of the related electromagnetic issues is required.This thesis focuses on the EMC characterisation of power electronic systems and contains two major phases.In the first phase, the high frequency characterisation of air-core reactors was considered. Air-core reactors are typically used in power systems for current limiting, ltering, shunting, and neutral grounding applications. It is of interest to understand the behaviour of air-core reactors in the presence of high frequency signals, especially from switching operations in the power electronic components. Using the partial element equivalent circuit (PEEC) approach, air-core reactor models, helpful in design and electromagnetic analysis, were created. The PEEC models were able to predict the current and voltage distributions and the eventual electromagnetic emissions at different frequencies. The second phase involved the characterisation of electromagnetic emissions from PWM drives using both modeling and measurement. A case study was performed on a prototype hybrid electric vehicle (HEV). Typically, emissions from PWM drives are expected at harmonics of the PWM switching frequency (fc) and harmonics of the fundamental frequency (f0) of the phase voltages. In this study, it was established that space vector PWM drives generate low-frequency pulsating (LFP) emissions at a frequency of 6f0. The switching of voltage vectors generates common mode current spikes because of the presence of stray capacitances and inductances. The spikes superpose across sector boundaries, forming spikes of double or triple amplitude that constitute the LFP emissions. The amplitudes of these ulsations were shown to be dependent on the drive parameters, such as the load, the speed, and the voltage slew rates. These common mode emissions enhance the emissions at harmonics of the switching frequency, create low-frequency emissions, and when injected into an electric motor, could cause torque pulsations and speed uctuations that may degrade drive functionality. Measurements from an HEV prototype show the LFP emissions, and theoretical models were developed to characterise them.Godkänd; 2010; 20100826 (mathen); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Mats Alaküla, Lund University and Volvo Car AB Ordförande: Professor Jerker Delsing, Luleå tekniska universitet Tid: Torsdag den 30 september 2010, kl 09.30 Plats: A1514 Demostudion, Luleå tekniska universitet
EM Karaktärisering och Modellering av Elektriska Hybriddrivsystem
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Delport, Pierre. "Optimisation of UHF radio SCADA systems for electrical distribution networks." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1905.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis presents the results of an investigation to establish methods to improve the performance of area radio based communication systems for Supervisory Control and Data Acquisition (SCADA) systems. The considerable scale on which an area radio network is used as a telecommunication network is quite unique to South Africa due to a lack of high bandwidth telecommunication systems in rural areas. Research was done to establish Key Performance Indicators (KPIs) to measure the performance of the area radio telecommunication systems. Two KPIs were chosen, namely Remote Terminal Unit (RTU) availability and Control Success Rate (CSR). These KPIs were trended over a three-year period to measure the effectiveness of measures taken to improve the systems. Two measures were implemented, namely to change the RTU radios, antennas and coaxial feeder cables and to redesign the communication systems in such a way to restrict multiple RTU protocols on the same area radio telecommunication network. The installation of new digital radios together with low loss coaxial cable and specific antennas improved the RTU availability from 96.87 % for the year 2002 to 99.17 % for the year 2004, which realised in an increase of 2.83 % for 432 installed RTUs. This measure, however, did not influence the CSR. The implementation of the newly designed communication networks had a significant influence on the control success rate of the SCADA systems and the KPI increased from 77.65 % for the year 2002 to 78.76 % for the year 2003 and 80.88 % for the year 2004. A drastic increase in performance was observed after the restriction of multiple RTU protocols on the same network during May 2004, where the value for twelve months prior to September 2005 was measured at 84.38 %. The utilisation of area radio telecommunication networks was measured for two operational networks and it was found to be well within the specifications of international accepted standards. One of these networks comprised of three repeaters and 84 installed RTUs and an average utilisation of 17 % and a peak utilisation of 25 % was measured. The other network had an installed base of 4 repeaters and 15 installed RTUs’s and an average utilisation of 3 % and a peak utilisation of 8 % was measured. This compares favourable with the IEEE standard 999-1992 [20], which recommends a channel utilisation of between 40 % and 60 %. Keywords : Key performance indicators, Radio telecommunication networks, Remote terminal unit
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Brady, Richard. "A Cross Platform Framework for Software Defined Radio." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2056.
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Thesis (MScEng (Electical and Electronic Engineering))--University of Stellenbosch, 2007.Software defined radios (SDRs) implement in software those parts of a radio which have traditionally been implemented in analogue hardware. We explain the importance of this definition and introduce reconfigurability and portability as two further goals. Reconfigurabilty is a property of the SDR platform, which may be a microprocessor, configurable hardware device, or combination of the two. We demonstrate that the field-programmable gate array is suficient for the implementation of practical SDR systems. Portability, on the other hand, is a property of the modulation and demodulation software, also known as waveform specification software. We evaluate techniques for achieving portability and show that waveforms can be specified in a generic form suitable for the autogeneration of implementations targetting both microprocessor- and FPGA-based architectures. The generated code is in C++ and VHDL respectively, and the tools used include formal models of computation and the XSLT language.
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Blaauw, Deon. "Flight control system for a variable stability blended-wing-body unmanned aerial vehicle." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2297.
Full textAbstract:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.This thesis presents the analysis, design, simulation and practical implementation of a novel control system for a variable stability blended-wing-body unmanned aerial vehicle. The aircraft has a moveable centre of mass that allows it to operate in an aerodynamically optimised minimum drag configuration during cruise flight. The primary purpose of the control system is thus to regain nominal static stability for all centre of mass positions, and then to further regulate motion variables for autonomous way point navigation. A thorough analysis of the parameters affected by the varying centre of mass position leads to the identification of the main control problem. It is shown that a recently published acceleration based control methodology can be used with minor modification to elegantly solve the variable stability control problem. After providing the details of the control system design, the customised avionics used for their practical implementation are presented. The results of extensive hardware in the loop simulations verify the functionality of the controllers. Finally, flight test results illustrate the practical success of the autopilot and clearly show how the control system is capable of controlling the variable stability aircraft at centre of mass locations where a human pilot could not.
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Jones, Jeffrey Alun. "Electronic reliability prediction : a study over 25 years." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/1991/.
Full textAbstract:
This thesis describes research work that the author has undertaken and published in the field of electronic reliability prediction techniques over the last 25 years. Reliability prediction is an important area since it has been part of the backbone of reliability engineering in one form or another for over fifty years. The author has over 45 publications that are within the area of reliability prediction and 13 of these have been selected for review in this thesis. In order to show how the author’s work has contributed to the field of reliability prediction this document also contains information on the history of reliability prediction. This allows the author’s work to be placed in context with general developments in the field. The contributions to knowledge and innovations that have been made in reliability prediction include the development of statistical models for lifetime prediction using early life data (i.e. prognostics); the use of non-constant failure rates for reliability prediction; the use of neural networks for reliability prediction, the use of artificial intelligence systems to support reliability engineers’ decision making; the use of a holistic approach to reliability; the use of complex discrete events simulation to model equipment availability; demonstration of the weaknesses of classical reliability prediction; an understanding of the basic behaviour of no fault founds; the development of a parametric drift model; identification of the use of a reliability database to improve the reliability of systems; and an understanding of the issues that surround the use of new reliability metrics in the aerospace industry.
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Ma, Yuefei. "Analysis of programmable molecular electronic systems." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5997.
Full textAbstract:
The continuing scaling down in size of microelectronics devices has motivated
the development of molecular electronic devices, often called moletronics, which use
molecules to function as electronic devices. One of the moletronics is the programmable
molecular array. In this device, disordered arrays of metallic islands are interlinked by
molecules. It is addressed by a small number of input/output leads located on the
periphery of the device.
In this dissertation, a thorough investigation of the programmable molecular
array is performed. First, theoretical calculations for single molecules are carried out.
The effect of bias voltage on the electron transmission through the molecule is reported.
Next, electrical measurements are conducted on programmable molecular arrays.
Negative differential resistance and memory phenomena are found. The electrical
characteristics of the programmable molecular array populated with different molecules
indicate that the metallic islands contribute to the above phenomena. The electrical conductance through the metallic islands is investigated, and conformational change of
the metallic islands under bias is reported.
Furthermore, a scenario is proposed to use molecular vibronics and electrostatic
potential to transport and process signals inside the programmable molecular array.
Simulated results are presented.
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Schneck, Jude Robert. "Femtosecond electronic dephasing and population relaxation of some novel semiconducting materials." Thesis, Boston University, 2012. https://hdl.handle.net/2144/34692.
Full textAbstract:
Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
The dissipation of energy by excited carriers in semiconductors is crucial to device development. In particular, the carrier relaxation mechanisms are strongly modified by the degree of disorder introduced into the lattice via the growth process. The pump probe spectroscopic technique is ideally suited to monitor the energy dissipation process and elucidate the relaxation mechanisms contributing to the carrier decay. Additionally, phase breaking interactions of optical transitions, as measured via the photon echo spectroscopic technique, provides insight into the different homogeneous relaxation mechanisms contributing to the optical resonance. When compared to high quality semiconducting materials, the fundamental homogeneous relaxation mechanisms depend strongly on the disorder inherent in the material. The photon echo technique is ideal for quantifying the strength of these interactions. Femtosecond pump-probe responses of a GaN thin film excited above and below the UV band gap were measured to determine the kinetic relaxation pathways of carriers. A number of fluence dependent decay processes were identified, including carrier-carrier scattering, exciton decay, trapping to defect states, and hole state recovery. The characteristic timescales of these mechanisms ranged from <50 fs to >600 ps. In other measurements on GaN, two-pulse photon echoes due to the strongly dipole coupled excitons were observed as a function of temperature (1 0 - 295K). A biexponential decay of the dephasing rate was found from these measurements and attributed to free and bound excitons. The dynamics of the E22 transition of (6,5) single walled carbon nanotubes was studied over a range of fluences via pump-probe spectroscopy. A fluence dependent dephasing rate was deduced from an analysis of the pump-probe signal intensity at a fixed short delay time allowing an effective cross section for exciton-exciton interactions to be determined. The relaxation kinetics of optically excited E22 excitons was revealed by pump fluence dependent fits to the observed pump-probe responses. The model includes both Auger recombination from the E11 and E22 states due to exciton-exciton annihilation and a stretched exponential decay from E11 to the valence band. E11 and E22 diffusion coefficients and the defect density were determined from this analysis.
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