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Dissertations / Theses on the topic 'Electrical Machine'
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1
Elschich, Ahmed. "Thermo-mechanical Fatigue of Electrical Insulation System in Electrical machine." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62579.
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Electrical machines in electrified heavy-duty vehicles are subjected to dynamic temperature loadings during normal operation due to the different driving conditions. The Electrical Insulation System (EIS) in a stator winding is aged as an effect of these dynamic thermal loads. The thermal loads are usually high constant temperatures and thermal cycling. The high average constant thermal load is well-known in the electrical machine industry but little is known about the effect of temperature cycling. In this project, the ageing of the EIS in stator windings due to temperature cycling is examined. In this project, computational simulations of different simplified models that represent the electrical insulation system are made to analyse the thermo-mechanical stresses that is induced due to thermal cycling. Furthermore, a test object was designed and simulated to replicate the stress levels obtained from the simulations. The test object is to ease the physical testing of electrical insulation system. Testing a complete stator takes time and has the disadvantage of having a high mass, therefore a test object is designed and a test method is provided. The results from the finite element analysis indicate that the mechanical stresses induced will affect the lifetime of the electrical insulation system. A sensitivity study of several thermal cycling parameters was performed, the stator core length, the cycle rate and the temperature cycle amplitude. The results obtained indicate that the stator core length is too short to have a significant effect on the thermo-mechanical stresses induced. The results of the sensitivity study of the temperature cycle rate and the temperature cycle amplitude showed that these parameters increase the thermo-mechanical stresses induced. The results from the simulations of the test object is similar to the results from the simulations of the stator windings, which means that the tests object is valid for testing. The test method that is most appropriate is the power cycling test method, because it replicates the actual application of stator windings. The thermally induced stresses exposing the slot insulation exceeds the yield strength of the material, therefore plastic deformation may occur only after one thermal cycle. The other components in the stator are exposed to stresses below the yield strength. The thermally induced stresses exposing the slot insulation are high enough to low cycle fatigue the electrical insulation system, thus thermo-mechanical fatigue is an ageing factor of the electrical insulation system.
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Shi, Bowen. "High performance permanent magnet electrical machine for electrical vehicle applications." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52331/.
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For electrical vehicle system, torque density, power density, output performance, high-speed range, reliability and cost are of the most importance. This means that the designing and manufacturing of high-performance traction system must be employed, regarding electrical machine, drive and battery. In this work, the main target is to propose and investigate methods for improving the designing of the electrical machine on EVs traction system. Permanent Magnet Synchronous Machine (PMSM) with the advantage on high power density, high efficiency and excellent power factor has been widely used in EVs applications, especially the high saliency type motor called Interior Permanent Magnet Machine (IPM). The use of performance map is a valuable evaluation tool for EVs machines, in terms of torque-speed ability and efficiency presentation. A FEM based performance mapping tool is designed and presented to improve such evaluation abilities, with motor control method evolved, advanced losses evaluation and optimal running time. With the evaluation tool secured, the design of an IPM traction motor is employed with prototype and experimental test, to deliver high power density, good torque performance, low harmonic content and wide speed capability. To ensure the smooth running of EVs, novel skewing method for motor, called modular skewing, is then introduced to archive optimal torque ripple minimization on IPM, rather than optimizing the cogging torque. The technique has been developed through vector redistribution algorithm and testified by 2D FEM modelling. Basing on the new designed IPM motor, a novel motor structure, named End-winding Flux Motor (EWFM), is invented, whose structure can be embedded to most type of conventional PMSM end-winding side for the purpose of end-winding utilization, power density increases and thermal improvements. In the end, the 3D FEM and experimental tests validate the concept of EWFM.
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Mukolera, J. "Logic programming in electrical machine design." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47359.
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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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MINERVINI, MARCELLO. "Multi-sensor analysis and machine learning classification approach for diagnostics of electrical machines." Doctoral thesis, Università degli studi di Pavia, 2022. http://hdl.handle.net/11571/1464785.
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Eriksson, Sture. "Electrical Machine Development : a study of four different machine types from Swedish perspective /." Stockholm : Elektriska maskiner & effektelektronik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4327.
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La, Rocca Antonino. "Thermal analysis of a high speed electrical machine." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33156/.
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This work has analysed, designed, commissioned and validated the performance of a novel cooling system for an innovative high speed, three-phase synchronous permanent magnet machine designed for an aero-engine starter/generator with a power rating of 45 kW and maximum speed of 32,000 rpm. The cooling system designed consisted into inserting a 1 mm non-electrically conductive stator sleeve in the machine airgap, this separates the rotor region from the stationary components letting the rotor running dry at all times; the stator region can then be flooded with oil. Oil enters from one side of the machine through some radial openings impinging directly over the end-winding, it then flows through two rows of equally sized axial ducts located along the inner and outer diameter of the stator to give an even distribution of the coolant, and finally it flows over the surface of the rear end-winding and leaves the machine. The thermal modelling was carried out by the joint use of Computational Fluid Dynamics (CFD) and Lumped Parameter Thermal Network (LPTN); this allowed the investigation of heat transfer phenomena and the optimisation of the cooling design. CFD was primarily employed to investigate the fluid flow and to perform conjugate heat transfer analyses; these allowed the determination of heat transfer coefficients and the prediction of temperature distribution inside the machine. Thermal networks were developed to investigate the heat flow through machine components, to perform the design optimisation and to maximise overall machine performance. A thermal network was also developed by the author to investigate the heat transfer phenomena inside the bearing chambers. An experimental apparatus was designed and commissioned in order experimentally validate the thermal models developed. Temperatures, pressures and torque up to 20,000 rpm were recorded throughout the tests and data collected were compared to quantities predicted analytically and numerically. Maximum winding temperatures measured performing a short circuit test agree well with analytical and numerical prediction with a maximum difference of 10%; mechanical losses measured carrying out a no-load test agree well at speeds over 10,000 rpm with differences between 2 and 12%. Throughout tests, pressure drops were monitored across the machine and an agreement of 13% with prediction were achieved. Design improvements are also proposed to further enhance the cooling of stator slots and of rotor components.
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Sparv, Lisa. "Cooling simulation of a BEV electrical machine rotor." Thesis, KTH, Fordonsdynamik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302143.
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The thesis work described in this report is about simulation of the cooling of an electrical machine rotor. Limitations and simplifications were made on the CAD model of the rotor with the purpose of reducing the simulation time, for it to then be used for CFD-simulations using STAR-CCM+. This was done to see the temperature, as well as its distribution, in the model. By changing various parameters, one at the time whilst the rest were kept at their assigned standard values, the changes could be analysed and thereafter compared. The tests include smaller geometry changes, parameters of the coolant and its flow, parameters for the airgap and the materials in the laminates and the material around the magnets, as well as changes in loss values. The simulations for geometry changes involving the magnets and their surrounding material resulted in minor temperature increases. An inner rotor radius increase gave a relatively large temperature decrease (although this change would be more difficult to make in practice). Most of the mean values of the temperature changes in the regions of the model were within 10% from the standard simulation used. Increased thermal contact resistance between the Bakelite and the laminates, and increased losses had the worst impact on the cooling. Meanwhile the changes in coolant parameters (as well as the its inlet temperature and mass flow) and reduced losses had the best impact on the cooling. Generally, the temperature distributions looked similar for the different simulations. There were more differences in the distributions for the simulations with changed material properties or thermal contact resistance.Examensarbetet som beskrivs i denna rapport handlar om simulering av kylningen av en elmaskinsrotor. Avgränsningar och vissa förenklingar gjordes på en CAD modell av rotorn för att reducera simuleringstiden. Sedan användes CFD-simuleringsprogrammet STAR-CCM+ för att simulera temperaturfördelningen i modellen. Genom att ändra olika parametrar, en åt gången medan resten hölls vid sina bestämda standardvärden, kunde förändringarna undersökas och sedan jämföras. Det som testades inkluderar bland annat mindre geometriförändringar, parametrar för kyloljan och dess flöde, parametrar för luftgapet och materialen i laminaten och runt permanentmagneterna, samt förlustförändringar. Geometriförändringarna som gjordes för magneterna och det omgivande materialet gav små temperaturökningar. En ökad inre radie på rotorn gav relativt stor temperaturminskning (men denna ändring vore svårare att genomföra på rotorn i praktiken). Majoriteten av medelvärdena av modellregionernas temperaturförändringar var inom 10% från standardsimuleringen som användes. Ökat termiskt kontaktmotstånd mellan Bakeliten och laminaten samt ökade förluster hade sämst påverkan för kylningen, medan förändring i kylvätskans egenskaperna (samt inflödestemperaturen och massflödet) samt minskade förluster hade bäst inverkan. Generellt så såg temperaturfördelningarna lika ut för de olika simuleringarna. Det var främst när materialegenskaperna eller det termiska kontaktmotståndet ändrades som fördelningen såg annorlunda ut.
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Norton, Mark B. "An object oriented approach to electrical machine design." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423486.
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Hillis, William Daniel. "The connection machine." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/14719.
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Collazo, Santiago Bryan Omar. "Machine learning blocks." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100301.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.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.
This work presents MLBlocks, a machine learning system that lets data scientists explore the space of modeling techniques in a very easy and efficient manner. We show how the system is very general in the sense that virtually any problem and dataset can be casted to use MLBlocks, and how it supports the exploration of Discriminative Modeling, Generative Modeling and the use of synthetic features to boost performance. MLBlocks is highly parameterizable, and some of its powerful features include the ease of formulating lead and lag experiments for time series data, its simple interface for automation, and its extensibility to additional modeling techniques. We show how we used MLBlocks to quickly get results for two very different realworld data science problems. In the first, we used time series data from Massive Open Online Courses to cast many lead and lag formulations of predicting student dropout. In the second, we used MLBlocks' Discriminative Modeling functionality to find the best-performing model for predicting the destination of a car given its past trajectories. This later functionality is self-optimizing and will find the best model by exploring a space of 11 classification algorithms with a combination of Multi-Armed Bandit strategies and Gaussian Process optimizations, all in a distributed fashion in the cloud.
by Bryan Omar Collazo Santiago.
M. Eng.
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Ullah, Aasim. "Investigation of Cogging Torque of a Downhole Drilling Machine and Optimization of Electrical Machine." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15224.
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This paper is a report on master thesis project conducted in cooperation with SMARTMOTOR AS and NTNU. The research for electrical downhole drilling machine has developed for decades. Permanent Magnet is a new addition in this arena. SMARTMOTOR AS built a downhole drilling machine which is needed to compare with machines from other competitors of the market. This machine has 10% cogging torque over its rated torque. The reason of this cogging torque and possible solutions has been investigated throughout this project. And a new geometry and design of the rotor (with 10 poles) is suggested for the machine in this report. Measurement shows the newer design is less sensitivity to eccentricity. at nominal load and speed. Lastly, flux weakening and magnet working point of the machine also investigated. In this report it is concluded that out of 3 experimental designs, the design with less epoxy and more magnet offer better performance regarding voltage waveform and vibrations. It is superior in terms of torque per weight. The other designs however allow easier manufacturing, better efficiency and shorter length of machine. It It is therefore concluded that the last design with less epoxy can be a suitable alternative rotor design for the built up machine which can reduce the existing cogging torque upto 83.4%. The end part of the paper describes a template-style of a generic electromagnetic modeling tool for the analysis and optimization of Electrical Machines. Further accurate virtual prototypes can then be produced to help designers provide answers on the performance of specific machine designs rapidly. And further investigations to identify the design characteristics of the perfect machine. A two and three-dimensional FEA model for a generator and motor can be created in minutes, investigations to identify the design characteristics of the perfect machine. Optimization tool assists designers to find the 'best' solution automatically. The tool is structured to allow creation and analysis of customized geometries, including special proprietary features. A new Matlab-based script is developed in order to handle the optimization process of electrical machine which will be used in the finite element analysis. The script saves the designer’s valuable time. It is concluded that ‘fmincon-constrained nonlinear minimization’ method in new optimization tool of MATLAB is more accurate and less time consuming compared to the method for optimization. The report explains a modern design procedure which uses both analytical and numerical analysis. The numerical analysis uses finite element analysis that is performed in Comsol mostly.
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Wang, Rong-Jie. "Design aspects and optimisation of an axial field permanent magnet machine with an ironless stator." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53351.
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Thesis (PhDEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The advent of new high energy product permanent magnet materials has opened great opportunities for novel electrical machine topologies with advantageous features such as high efficiency and high power/weight ratio. Amongst others, axial field permanent magnet (AFPM) machines with ironless stators are increasingly being used in power generation applications. Because of the absence of the core losses, a generator with this type of design can operate at a substantially high efficiency. Besides, the high compactness and disc-shaped profile make this type of machine particularly suitable for compact integrated power generation systems. Due to construction problems, the generator application of this type of machine has been limited to quite a low power range. There is a need to investigate the performance capability of this type of AFPM machine in the upper medium power level. The focus of this thesis is on the design optimisation of the air-cooled AFPM generator with an ironless stator. A design approach that directly incorporates the finite element field solution in a multi-dimensional optimisation procedure is developed and applied to the design optimisation of a 300 kW (at unity power factor) AFPM generator. To enable an overall design optimisation of the machine, different design aspects, such as the cooling capacity, the mechanical strength and eddy loss, are also studied in this research. To enable the free movement of the rotor mesh with respect to the stator mesh, the air-gap element originally proposed by Razek et. al. is derived for Cartesian coordinate systems. For minimising the large computation overhead associated with this macro element, a number of existing time-saving schemes have been utilised together with the derived Cartesian air-gap element. The developed finite element time-step model is applied to calculating the steadystate performance of the AFPM machine. Since the flux distribution in an AFPM machine is three dimensional by nature, calculating the eddy current loss by merely using a simple analytical method may be subject to a significant error. To overcome this problem, the two dimensional finite element field modelling is introduced to perform accurate field analysis. To exploit the full advantages of the twodimensional finite element modelling, a multi-layer approach is proposed, which takes into account the variation of the air-gap flux density in the conductors with regard to their relative positions in the air-gap. To account for the radial variation of the field, a multi-slice finite element modelling scheme is devised. The thermal analysis is an important aspect of the design optimisation of AFPM machines. From a design point of view, it is preferable to have a simple but effective method for cooling analysis and design, which can easily be adapted to a wide range of AFPM machines. In this thesis a thermofluid model of the AFPM machine is developed. The fluid flow model is needed for calculating the air flow rate, which is then used to find the convective heat transfer coefficients. These are important parameters in the subsequent thermal calculations. Experimental investigations have been carried out to verify each of the above-mentioned models/methods. With these models implemented, the design optimisation of an air-cooled ironless stator 300 kW (at unity power factor) AFPM generator is carried out. The performance measurements done on the fabricated prototype are compared in this thesis with predicted results. The study shows that the proposed design approach can be applied with success to optimise the design of the AFPM machine. The advantages of high power density, high efficiency, no cogging torque and good voltage regulation make this type of AFPM machine very suitable for power generator applications. The optimum steady-state performance of the AFPM machine shows that this machine with an ironless stator is an excellent candidate for high speed power generator applications, even in the upper medium power level. The good cooling capacity of this type of machine holds the promise of its being a self-cooled generator at high power ratings.
AFRIKAANSE OPSOMMING: Die uitvinding van nuwe hoë energiedigtheid permanent magneet materiale het groot geleenthede vir nuwe elektriese masjien topologië laat ontstaan met voordelige eienskappe soos hoë benuttingsgraad en hoë drywing/gewig verhouding. Onder andere word die aksiaalveld permanente magneet (AVPM) masjiene met kernlose stators toenemend gebruik vir elektriese generator toepassings. As gevolg van die afwesigheid van kernverliese kan 'n generator met hierdie tipe ontwerp teen 'n aansienlik hoë benuttingsgraad werk. Daarbenewens maak die hoë kompaktheid en skyfvorm-profiel die masjien in besonder geskik vir die ontwikkeling van kompak geïntegreerde drywing generator stelsels. As gevolg van konstruksie probleme is die toepassing van hierdie tipe masjien as generator beperk tot redelik lae drywingsgebiede. Dit is nodig om die werkverrigtingsvermoë van hierdie tipe AVPM masjien in die boonste medium drywingsgebied te ondersoek. Die fokus van hierdie tesis is op die ontwerp-optimering van 'n lugverkoelde AVPM generator met 'n kernlose stator. 'n Ontwerpsbenadering wat die eindige element veldoplossing in 'n multi-dimensionele optimeringsprosedure insluit, is ontwikkel en toegepas op die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) AVPM generator. Om 'n globale ontwerpsoptimering van die masjien te kan doen is verskillende ontwerpsaspekte soos die verkoelingskapasiteit, meganiese sterkte en werwelverliese ook in hierdie navorsing bestudeer. Om die vrye beweging van die rotormaas ten opsigte van die statormaas te verseker is die lugspleet-element, soos oorspronklik deur Razek et al voorgestel, afgelei vir Cartesiaanse koórdinaat stelsels. Om die lang berekeningstyd geassosieer met hierdie makro-element te minimaliseer is 'n aantal bestaande tydbesparende metodes saam met die ontwikkelde Cartesiaanse lugspleet-element gebruik. Die ontwikkelde eindige element tydstapmodel is toegepas om die bestendige werkverrigting van die AVPM masjien te bereken. Aangesien die vloedverspreiding in 'n AVPM masjien van nature drie-dimensioneel is, kan die berekening van die werwelstroomverliese tot aansienlike foute lei as eenvoudige analitiese metodes gebruik word. Om hierdie probleem te oorkom is twee-dimensionele eindige element modellering gebruik om akkurate veld-analise te doen. Om die volle voordele van die twee- dimensionele eindige element modellering te eksploiteer is 'n multi-laag benadering voorgestel wat die variasie van die lugspleetvloeddigtheid in die geleiers met betrekking tot hulle relatiewe lugspleetposisies in ag neem. Om voorsiening te maak vir die radiale variasie van die veld, is 'n multi-skyf eindige element modelleringstegniek ontwikkel. Die termiese analise is 'n belangrike aspek van die ontwerpsoptimering van AVPM masjiene. Vanuit 'n ontwerpsoogpunt is dit verkieslik om 'n eenvoudige maar tog effektiewe metode van verkoelingsanalise en -ontwerp te hê wat maklik toegepas kan word op 'n wye reeks van AVPM masjiene. In hierdie tesis word 'n termovloeimodel van die AVPM masjien ontwikkel. Hierdie vloeimodel is nodig vir die berekening van die lugvloeitempo, wat op sy beurt weer nodig is om die konveksie hitte-oordrag koëffisiënte te bepaal. Hierdie is belangrike parameters in die opvolgende termiese berekeninge. Eksperimentele ondersoek is uitgevoer om elkeen van die bogenoemde modelle en metodes te verifieer. Nadat hierdie modelle geïmplimenteer is, is die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) lugverkoelde kernlose stator AVPM generator uitgevoer. Die werkverrigtingmetings gedoen op 'n vervaardigde prototipe masjien, word in hierdie tesis vergelyk met voorspelde resultate. Daar word getoon dat die voorgestelde ontwerpsbenadering met sukses toegepas kan word om die ontwerp van die AVPM masjien te optimeer. Die voordele van hoë drywingsdigtheid, hoë benuttingsgraad, geen vertandingsdraaimomente en goeie spanningsregulasie maak hierdie masjien baie aantreklik vir generator toepassings. Die optimum bestendige werkverrigting van die AVPM masjien toon dat hierdie masjien met 'n kernlose stator 'n goeie kandidaat is vir hoë spoed generator toepassings, selfs in die boonste medium drywingsgebied. Die goeie verkoelingskapasiteit van hierdie tipe masjien hou die belofte in van'n selfverkoelde generator by hoë drywing aanslae.
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Bahceci, Mesut. "Simulation of an Electrical Machine : with superconducting magnetic bearings." Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-242127.
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This master thesis investigates if there is an induction motor configuration that can be used with a flywheel energy storage system, that uses passve superconducting magnetic bearings (SMBs). The configurations should be able to be designed with induction motor building blocks that are commercially available. The method used to investigate this was simulations of different induction motor configurations in the finite element analysis software COMSOL. The simulations show that when larger air-gaps than that of a commercial IM unit are used it is possible to use SMBs in the IM. SMBs have the advantage of having zero resistance which makes it possible to store energy without resistance losses. However it was found that by using and IM with SMBs the generated power would be lower than that of a commercial unit.
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Patel, Darshan D. "Vehicle classification using machine learning algorithm." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1604876.
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Increasing traffic on roadways requires some real-time system that can collect traffic data and helps us to manage existing road infrastructure. For this purpose, we need a state of art system that can detect and classify vehicles into different categories. We developed an in-node microprocessor-based vehicle classification system to analyze and determine the types of vehicles passing over a 3-axis magnetometer sensor. Our approach for vehicle classification utilizes J48 classification algorithm, which is implemented in machine learning software Weka. J48 is a Quinlan's C4.5 algorithm, an extension of decision tree machine learning based on ID3 algorithm. The decision tree model is generated from a set of features extracted from vehicles passing over the 3-axis sensor. The generated tree model can then be easily implemented on microprocessors. The result of our experiment shows that the vehicle classification system is effective and efficient with the very high accuracy at ~98%.
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Swint, Ethan Baggett. "DC Reluctance Machine — A Doubly-Salient Reluctance Machine with Controlled Electrical and Mechanical Power Ripple." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/27717.
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Doubly-Salient Reluctance Machines (DSRMs) sidestep many of the issues with permanent
magnet and induction machines and embody the lowest cost and simplest manufacturing of the
motor technologies. Major drawbacks to RMs have been (1) the need for failure-prone
electrolytic capacitors, (2) large torque ripple, and (3) acoustic noise. Conventionally, these
drawbacks have been addressed independently either through (1) excitation control or (2)
machine design, but not as a holistic system or solution. This disseratation presents a design for
high-efficiency low-cost RM while producing smooth output torque and avoiding pulsating
inverter input current and the associated electrolytic capacitor. We propose a method for shaping
the machine reluctance profile to reduce machine torque ripple to a desired level (here, <5%)
without compromising on machine efficiency or power density, a Shaped Reluctance Machine
(ShRM). Furthermore, a comprehensive approach which combines both phase excitation control
and machine design to cooperatively address the excursions of input and output powers from
their average values which results in less than 5% ripple for both electrical and mechanical net
power â essentially a DC Reluctance Machine (DCRM). Compared to conventional practice in
DSRMs, electrical power ripple is reduced by 85 times and torque ripple is reduced by almost 20
times, while overall efficiency, torque density, and power density are maintained.Ph. D.
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Odero, Christine A. (Christine Adhiambo). "Polymer gel spinning machine." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34092.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 117-118).
by Christine A. Odero.
M.S.
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Streeter, Kenneth Brett. "A partitioned computation machine." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/80459.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (leaves 86-88).
by Kenneth Brett Streeter.
M.S.
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Perdikakis, William S. "Electric Machine and Converter Power Sourcing Challenges of More Electric Aircraft." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1620676445543609.
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Zhang, YuQi. "ADVANCED SYNCHRONOUS MACHINE MODELING." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/118.
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The synchronous machine is one of the critical components of electric power systems. Modeling of synchronous machines is essential for power systems analyses. Electric machines are often interfaced with power electronic components. This work presents an advanced synchronous machine modeling, which emphasis on the modeling and simulation of systems that contain a mixture of synchronous machines and power electronic components. Such systems can be found in electric drive systems, dc power systems, renewable energy, and conventional synchronous machine excitation. Numerous models and formulations have been used to study synchronous machines in different applications. Herein, a unified derivation of the various model formulations, which support direct interface to external circuitry in a variety of scenarios, is presented. Selection of the formulation with the most suitable interface for the simulation scenario has better accuracy, fewer time steps, and less run time.
Brushless excitation systems are widely used for synchronous machines. As a critical part of the system, rotating rectifiers have a significant impact on the system behavior. This work presents a numerical average-value model (AVM) for rotating rectifiers in brushless excitation systems, where the essential numerical functions are extracted from the detailed simulations and vary depending on the loading conditions. The proposed AVM can provide accurate simulations in both transient and steady states with fewer time steps and less run time compared with detailed models of such systems and that the proposed AVM can be combined with AVM models of other rectifiers in the system to reduce the overall computational cost.
Furthermore, this work proposes an alternative formulation of numerical AVMs of machine-rectifier systems, which makes direct use of the natural dynamic impedance of the rectifier without introducing low-frequency approximations or algebraic loops. By using this formulation, a direct interface of the AVM is achieved with inductive circuitry on both the ac and dc sides allowing traditional voltage-in, current-out formulations of the circuitry on these sides to be used with the proposed formulation directly. This numerical AVM formulation is validated against an experimentally validated detailed model and compared with previous AVM formulations. It is demonstrated that the proposed AVM formulation accurately predicts the system's low-frequency behavior during both steady and transient states, including in cases where previous AVM formulations cannot predict accurate results. Both run times and numbers of time steps needed by the proposed AVM formulation are comparable to those of existing AVM formulations and significantly decreased compared with the detailed model.
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Liang, Qianhui S. M. Massachusetts Institute of Technology. "Machine mediated human perception." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129882.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Architecture, September, February, 2020Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, February, 2020
Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 71-76).
'The broader one's understanding of the human experience, the better design we will have.' --Steve Jobs In recent decades, there has been a growing interest in designing places through the lenses of the human experience. However, research on the relationship between the physical environment and its influence on human perception has been constrained. The constraint is partially due to the difficulty of assessing perception and physical features through objective mathematical models. The idea of this thesis is to explore how machine learning can contribute to better integration of previously unquantifiable human perception with urban theories matrix in the design process: In particular, the thesis will investigate the relationship between the built environment features and the human's perception at the street level. The thesis explore machine learning methodologies, combining computer vision's application in modeling building features, in assessment of urban landscape liveliness: Taking the central area of Shanghai as the experimental site, the thesis designs a crowd-sourcing platform to collect residents' perception of streets in Shanghai by evaluating street spaces displayed in the form of rendered 3D model scenes and panoramic videos. I revisit urban study principles to define a matrix of spatial features and simulate such perceptions through a machine learning approach. This AI-assisted pipeline will shed light on how features of the urban environment influence individuals' perceptions and to further assist with decision-making toward human-centered urban design.
by Qianhui Liang.
S.M.
S.M.
S.M. Massachusetts Institute of Technology, Department of Architecture
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Alam, S. M. Mahfuz. "Direct Torque Control of AC Machine Drives." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10128872.
Full textAbstract:
Field oriented control (FOC) and direct torque control (DTC) are the two most important control strategies for modern advanced machine drives. Field oriented control (FOC) has been widely used as the industrial motor drives. The direct torque control has been recently developed by Takashi and has shown great potential in machine drive applications. This thesis discusses the performances of direct torque control on AC machine drives including the industrial workhorse induction machines (IM) and permanent magnet synchronous machines (PMSM). Both of the IM and PMSM dynamics models are derived in details in the thesis. By applying nonlinear filtering techniques, the sensorless direct torque control of AC machine drives are studied. MATLAB simulations have shown the efficacy and superior performance of the resilient extended Kalman filter over the traditional extended Kalman filter for direct torque control applications.
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Bhattarya, Rahul. "In-Node Machine Learning-based Vehicle Classification." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10837826.
Full textAbstract:
Over the last few decades, our nation has experienced a significant increase in the amount of traffic congestion on freeways and intra-city roads. The current technology designed to control and improve this national problem has met with some real success. Based on inductive loops, that system’s ability to detect the presence of cars and, therefore, the frequency of use of roads has been a great boon. However, the system is not perfect; moreover, based on projections for future use of road infrastructure, the inductive loops solution will not be adequate for long. Continued smooth operations of our road infrastructure require that some more effective solution be developed.
Towards that end, this report proposes a new approach, building on the strengths of its predecessors. This new method utilizes an in-node Machine Learning-based Vehicle Classification (MLVC) system and promises to offer more comprehensive and valuable metrics than has been previously possible. Moreover the system is extremely efficient, boasting attributes such as low power consumption, minimal space requirements, and small associated costs; these features enable the system to technically outperform many existing vehicle-detection systems. Based on its features and performance, this system promises to be an ideal choice for monitoring and alleviating traffic congestion. Used on a wide scale, it could greatly increase the efficiency of our nation’s infrastructure and improve the quality of life of the millions who use our roads and highways.
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Karimi, Ahmad Maroof. "Distributed Machine Learning Based Intrusion Detection System." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1470401374.
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Harrison, Kyle. "Machine Learning for Radio Frequency Interference Flagging." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33777.
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The field of radio frequency interference (RFI) flagging involves the identification of corrupted data within radio astronomy measurements. This work explores the application of supervised machine learning algorithms for RFI flagging, trained on real measurement data and simulated data with simulated RFI. The goal of this work is to investigate the prediction of RFI using specific machine learning algorithms; Naive Bayes Classifier, K-Nearest Neighbours Classifier, Random Forest Classifier, the U-Net convolution neural network and the Multilayer Perceptron. These algorithms are trained on real data, in which the ground truth includes inherent false positives, and simulated data where the ground truth positions of RFI are absolute. This is done through the use of time/frequency spectrogram data, relating to radio astronomy measurements, using the magnitudes and phases of each available polarization. Predictions for unseen test data are compared between algorithms, different implementations of those algorithms and each dataset. A specific implementation for data pre-processing is designed and implemented, utilizing a two dimensional filtering technique for feature construction. The goal of this method is intended to implement a means of injecting a form of spatial information of nearby time/frequency samples for each sample in a spectrogram. The inclusion of this spacial information, which is relevant to broadband bursts and narrowband persistent RFI, is hypothesised to increase the level of information present in the processed dataset. The use of feature construction using filtering techniques, demonstrates a noticeable improvement in the machine learning methods where each sample is treated individually during training and inference.
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Grop, Henrik. "Investigation of AC electrical machine stators with fractional conductor windings." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12472.
Full textAbstract:
Industry always searches the least expensive solution for a machine design. Therefore, there is a need for integrating different customer ordered machines within the same frame, while keeping the foundation of the mechanical design constant. Since the winding design in electrical machines is essential for the performance and relatively inexpensive to adapt, it can be used to meet different customer demands. This thesis investigates the foundations of a special winding named fractional conductor winding. An expression for winding factors for certain kinds of these windings is developed. Calculations showed that the selection of the winding distribution has effect on the air gap space harmonics produced by the winding. In some cases, the fifth and seventh space harmonics can be eliminated by the use of fractional conductor windings in combination with short pitching. The construction of a prototype fractional conductor wound induction motor was documented and is presented in this thesis. The air gap flux density in a dual slotted fractional conductor wound induction motor running at no load is studied. Analytical models are compared to results obtained by finite elements and measurements. It was found that analytical results overestimated the peak of the fundamental flux density by 13.5%. The overestimation was caused by the iron reluctance of the main flux path as well as saturation. Leakage was found to be a minor cause of this overestimation. Slot leakage and differential leakage in machines having these windings are studied. The analytical models were evaluated, with mostly good agreements, compared to finite element modeling as well as measurements.
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Kouadria, Djilali. "The ageing and breakdown characteristics of electrical machine insulation materials." Thesis, University of Brighton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264002.
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Kockelbergh, David. "The origins of student misunderstanding of undergraduate electrical machine theory." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16072.
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This thesis is concerned with student understanding of key concepts in electrical engineering teaching within higher education. Anecdotal evidence suggests that many students struggle to understand threshold concepts and therefore encounter difficulties in learning theoretical models which are underpinned by such theoretical concepts. This research utilised a mixed methods approach to investigate the factors that influence student understanding of key theoretical concepts within electrical engineering. The initial study used a questionnaire to evaluate student understanding of concepts which were identified by teaching staff as being core to a particular module. The study identified that students commenced the module with poor understanding and that instruction on the module ELC040 Electrical Machines and Systems did not lead to improved understanding of core concepts. This suggests that the roots of student misunderstanding lay elsewhere. Desk research was subsequently employed to explore the sources of student misunderstandings. Performance data was analysed and demonstrated that the roots of the student misunderstanding of Electrical Machine Theory lay in the pre-requisite module Electrical Power B. Students routinely failed to achieve high levels of understanding in this module and as a result were unable to successfully build upon it in the third year module. Semi-structured interviews were then undertaken with Part C students who were undertaking the Electrical Machines and Systems module. In addition, structured interviews were administered with the Part B students. The interviews aimed to establish the study practices adopted by students across both years. The study showed that students found the ELA001 module difficult, and the majority believe that most other students felt the same way as they did. Students provided evidence of poor study techniques, by reporting last minute sessions to complete coursework and last minute revision for exams. This research informed the development of an interactive learning tool which was piloted on a small cohort of students. The research has also established that there are many influences on the development of student understanding of threshold concepts within electrical engineering and argues for a more active style of teaching in order to address student misunderstanding.
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Tan, Johnson Cheah-Shin. "A machine utilization analysis tool." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/37773.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 76-77).
by Johnson Cheah-Shin.
M.S.
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Shih, Lawrence Kai 1974. "Machine learning on Web documents." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28331.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (leaves 111-115).
The Web is a tremendous source of information: so tremendous that it becomes difficult for human beings to select meaningful information without support. We discuss tools that help people deal with web information, by, for example, blocking advertisements, recommending interesting news, and automatically sorting and compiling documents. We adapt and create machine learning algorithms for use with the Web's distinctive structures: large-scale, noisy, varied data with potentially rich, human-oriented features. We adapt two standard classification algorithms, the slow but powerful support vector machine and the fast but inaccurate Naive Bayes, to make them more effective for the Web. The support vector machine, which cannot currently handle the large amount of Web data potentially available, is sped up by "bundling" the classifier inputs to reduce the input size. The Naive Bayes classifier is improved through a series of three techniques aimed at fixing some of the severe, inaccurate assumptions Naive Bayes makes. Classification can also be improved by exploiting the Web's rich, human-oriented structure, including the visual layout of links on a page and the URL of a document. These "tree-shaped features" are placed in a Bayesian mutation model and learning is accomplished with a fast, online learning algorithm for the model. These new methods are applied to a personalized news recommendation tool, "the Daily You." The results of a 176 person user-study of news preferences indicate that the new Web-centric techniques out-perform classifiers that use traditional text algorithms and features. We also show that our methods produce an automated ad-blocker that performs as well as a hand-coded commercial ad-blocker.
by Lawrence Kai Shih.
Ph.D.
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Gurevich, Yevgeny. "The M-Machine operating system." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/37041.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 117-118).
by Yevgeny Gurevich.
M.Eng.
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Park, Allen S. M. (Allen S. ). Massachusetts Institute of Technology. "Machine-vision assisted 3D printing." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/113162.
Full textAbstract:
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 71-72).
I augmented a 3D printer with software for a 3D scanning system in order to incorporate feedback into the printing process. After calibration of the scanning system and the printer, the 3D scanning system is capable of taking depth maps of the printing platform. The two main extensions of 3D printing enabled by the 3D scanning system are printing on auxiliary objects and corrective printing. Printing on auxiliary objects is accomplished by scanning an auxiliary object, then positioning the printer to print directly onto the object. Corrective printing is using the scanner during the printing process to correct any errors mid-print.
by Allen Park.
M. Eng.
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Evgeniou, Theodoros K. (Theodoros Kostantinos) 1974. "Learning with kernel machine architectures." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86442.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 99-106).
by Theodoros K. Evgeniou.
Ph.D.
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Lundgard, Alan. "Measuring justice in machine learning." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130203.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, September, 2020"September 2020." Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 29-36).
How can we build more just machine learning systems? To answer this question, we need to know both what justice is and how to tell whether one system is more or less just than another. That is, we need both a definition and a measure of justice. Theories of distributive justice hold that justice can be measured (in part) in terms of the fair distribution of benefits and burdens across people in society. Recently, the field known as fair machine learning has turned to John Rawls's theory of distributive justice for inspiration and operationalization. However, philosophers known as capability theorists have long argued that Rawls's theory uses the wrong measure of justice, thereby encoding biases against people with disabilities. If these theorists are right, is it possible to operationalize Rawls's theory in machine learning systems without also encoding its biases? In this paper, I draw on examples from fair machine learning to suggest that the answer to this question is no: the capability theorists' arguments against Rawls's theory carry over into machine learning systems. But capability theorists don't only argue that Rawls's theory uses the wrong measure, they also offer an alternative measure. Which measure of justice is right? And has fair machine learning been using the wrong one?
by Alan Lundgard.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Li, Shuang S. M. Massachusetts Institute of Technology. "Machine social intelligence in Virtualhome." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129367.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, September, 2020Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 49-53).
This thesis introduces a Watch-And-Help (WAH) challenge and a multi-agent environment for testing social intelligence in multiple agents. In the challenge, an AI agent needs to help a human-like agent perform a complex household task efficiently. To succeed, the AI agent needs to i) understand the underlying goal of the task by watching a single demonstration of the human-like agent performing the same task (social perception), and ii) coordinate with the human-like agent to solve the task in an unseen environment as fast as possible (human-AI collaboration). For this challenge, we build VirtualHome-Social, a multi-agent household environment, and provide a benchmark including both planning and learning based baselines. Experimental results demonstrate that in order to achieve success in the challenge, an AI agent has to accurately understand and predict the human-like agent's behaviors, and adapt its collaborative plan accordingly in novel environments.
by Shuang Li.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Nguyen, V. "Nanodielectrics for machine insulation." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359140/.
Full textAbstract:
Thanks to the development of nanotechnology, epoxy nanocomposites have been expected to be potential candidates to replace the base resin, due to their superior properties. However, the effects of nano-fillers have been controversial, in both positive and negative ways. There are two main factors, comprising of stoichiometry and the nature of interfacial areas of nano-sized fillers, which are expected to contribute to the final properties of epoxy nanocomposites. The chosen stoichiometry is important in determining the nature of the polymer network that forms. A stoichiometric formulation with the optimal chemical balance between reactants will introduce good performance. However, incorporation of nano-fillers with large interfacial areas into epoxy matrices may modify the cure behaviour of the system, through introducing additional chemical reactions between moieties on the nano-filler surfaces and reactants, thereby altering the rate and sequence of the possible chemical reactions that occur during curing. These effects change the chemical balance of the original base resin system. As a result, the nature of the cross-linked network that forms may be altered. An investigation into the effects of stoichiometry and the nature of the interfacial surface of treated nanosilica particles of various sizes on properties of epoxy-based systems has been conducted, using the differential scanning calorimetry, space charge and ac breakdown measurements, and the dielectric spectroscopy. The introduction of nanosilica has induced changes in curing mechanisms and led to different impacts on systems of different resin stoichiometry. In addition, the investigation has revealed a key role of the characteristic interaction between the nanoparticle surface and the resin matrix in determining material properties, rather than the filler size. Weak interactions have produced negative impacts on material properties. The addition of nano-silica particles into conventional microcomposites has suggested the possible synergetic effects due to the presence of both nano and micro fillers. Furthermore, the long-term performance of the unfilled epoxy and its nanocomposites has been explored. Open branch trees with the faster propagation rate have been observed in nanocomposites, compared to the unfilled epoxy. The material degradation during partial discharge activities has also been evinced using the confocal Raman microprobe spectroscopy.
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Rodriguez, Marvin O. "Automated peritoneal dialysis (APD) machine modeling." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10196401.
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A peritoneal dialysis cycler model was developed to be used by biomedical device manufacturers in order to aid them in the system development, system level requirement writing, and FDA device certification process. This generic model can be used as a plug and play model for companies to incorporate a specific dialysis pump that is commercially available and quickly integrate it into their system. The Simulink model was used to simulate the system behavior and analyze multi domain dynamic systems data. A mathematical representation of the physical system was derived using fluid dynamic equations. The mathematical equations were then translated into Simulink blocks for the computer environment to understand. A proportional integral derivative controller was designed and integrated into the system in order to compensate the flow rate for any difference between the flow set point and the actual flow. System monitors were developed to protect patients from hazardous conditions.
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Bomela, Xola B. "Some design aspects of the multi flux barrier rotor reluctance synchronous machine." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51912.
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Thesis (MEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: This thesis deals with different design aspects of the multi-flux barrier rotor of the reluctance synchronous machine (RSM). The effect of the different designs on the performance of the RSM is investigated by means of two-dimensional finite element analysis. The finite element analysis is also directly used in the optimum design of the rotor of the RSM. The importance of the use of the finite element analysis in the design and performance calculations of the RSM is illustrated in this thesis. The design aspects of the RSM which are focussed on in this thesis are, amongst other things, the chording of the stator winding, the skewing of the rotor and the ratio of the number of rotor flux barriers to the number of stator slots of the RSM. The effects of these design aspects on the average torque and torque ripple of the RSM are investigated and general design directives are given. The occurrence of flux pulsations in the stator teeth and rotor iron segments of the RSM are also studied to some extent. The finite element optimum design of a4-pole RSM-rotor with a high number of flux barriers is described in the thesis. This optimum designed rotor is built and the RSM with this rotor is tested in the laboratory. Its calculated and measured performances are studied and compared with a conventional, low number rotor flux barrier RSM. It is found, amongst other things, that the RSM with the high number of rotor flux barriers has a slightly higher average torque with a significantly lower torque ripple.
AFRIKAANSE OPSOMMING: Hierdie tesis handeloor verskillende ontwerp-aspekte van die reluktansie sinchroonmasjien (RSM) met 'n multi-vloedversperringsrotor. Die effek van die verskillende ontwerpe op die vermoë van die RSM is met behulp van twee-dimensionele eindige element analise ondersoek. Die eindige element analise is ook direk in die optimum ontwerp van die rotor van die RSM gebruik. Die belangrikheid van die gebruik van die eindige element analise in die ontwerp en vermoë-berekening van die RSM word in die tesis geïllustreer. Die ontwerp-aspekte van die RSM waarop in hierdie tesis gefokus word, is onder andere die spoelsteekverkorting van die statorwikkeling, die skuinsing van die rotor en die verhouding van die getal rotor-vloedverperrings tot die getal statorgIeuwe van die RSM. Die effek van hierdie ontwerpaspekte op die gemiddelde draaimoment en draaimoment-rimpel van die RSM word ondersoek en algemene riglyne vir die ontwerp van die RSM word gegee. Die voorkoms van vloedpulsasies in die statortande en rotor yster segmente van die RSM word ook deels ondersoek. Die eindige element optimum ontwerp van 'n 4-pool RSM-rotor met 'n hoe getal vloedversperrings word in die tesis beskryf. Hierdie optimum ontwerpte rotor is gebou en die RSM met hierdie rotor is in die laboratorium getoets. Die berekende en gemete vermoë is bestudeer en vergelyk met die vermoë van 'n RSM met 'n konvensionele, lae getal vloedversperrings rotor. Dit is onder andere gevind dat die RSM met die hoë getal rotor-vloedversperrings 'n effens hoër gemiddelde draaimoment het met 'n behuidende laer draaimoment-rimpel.
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Hamilton, Brandon Kyle. "MURAC: A unified machine model for heterogeneous computers." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16519.
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Includes bibliographical referencesHeterogeneous computing enables the performance and energy advantages of multiple distinct processing architectures to be efficiently exploited within a single machine. These systems are capable of delivering large performance increases by matching the applications to architectures that are most suited to them. The Multiple Runtime-reconfigurable Architecture Computer (MURAC) model has been proposed to tackle the problems commonly found in the design and usage of these machines. This model presents a system-level approach that creates a clear separation of concerns between the system implementer and the application developer. The three key concepts that make up the MURAC model are a unified machine model, a unified instruction stream and a unified memory space. A simple programming model built upon these abstractions provides a consistent interface for interacting with the underlying machine to the user application. This programming model simplifies application partitioning between hardware and software and allows the easy integration of different execution models within the single control ow of a mixed-architecture application. The theoretical and practical trade-offs of the proposed model have been explored through the design of several systems. An instruction-accurate system simulator has been developed that supports the simulated execution of mixed-architecture applications. An embedded System-on-Chip implementation has been used to measure the overhead in hardware resources required to support the model, which was found to be minimal. An implementation of the model within an operating system on a tightly-coupled reconfigurable processor platform has been created. This implementation is used to extend the software scheduler to allow for the full support of mixed-architecture applications in a multitasking environment. Different scheduling strategies have been tested using this scheduler for mixed-architecture applications. The design and implementation of these systems has shown that a unified abstraction model for heterogeneous computers provides important usability benefits to system and application designers. These benefits are achieved through a consistent view of the multiple different architectures to the operating system and user applications. This allows them to focus on achieving their performance and efficiency goals by gaining the benefits of different execution models during runtime without the complex implementation details of the system-level synchronisation and coordination.
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Mwaba, Gomezyani. "Permanent Magnet Machine Topologies for high speed flywheels." Thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5145.
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Crida, Robert Charles. "A machine vision approach to rock fragmentation analysis." Doctoral thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/9228.
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Bibliography: p. 217-223.[pp. i - iv missing] This thesis is concerned with the development of an instrument for the purpose of performing online measurement of rock size distribution using machine vision. This instrument has application in the gold mining industry where it could be used to measure the fragmentation of gold ore on a conveyor belt feed to an autogenous mill, for the purpose of controlling the mill. The gold ore can range in size from fine material (< 20mm) to very large rocks (0.5m). A machine vision approach is only capable of directly measuring the projected area of particles at the surface of the rock-stream. A volume distribution has to be estimated from this using a stereological method. These methods have been investigated previously and are typically error prone. They have not been investigated here. An investigation of lighting demonstrates that a diffuse lighting arrangement is suitable for this application. This would have two advantages: specular reflection from wet material is suppressed; and intensity values can be used to predict the orientation of the surface of the particles. A computational structure has been developed to identify and delineate rocks in an image for the purpose of measuring their areas. It is based on the human visual system in that it consists of a low-level preattentive vision stage and a higher-level stage of attention focusing. Multiscalar image processing techniques have also been integrated in order to improve the detection of rocks across a wide range of sizes. A performance advantage can be obtained in this way because all the algorithms can be better matched to the size of the objects being detected. Results have been obtained with an average true detection rate of 69 and a further close miss rate of 14 , with very few false alarms. The overall result is that the measured projected area distribution closely matches the true value for each test image.
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Bao, Yujia. "Deriving machine attention from human rationales." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122878.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-50).
Attention-based models are successful when trained on large amounts of data. In this thesis, we demonstrate that even in the low-resource scenario, attention can be learned effectively. To this end, we start with discrete human-annotated rationales and map them into continuous attention. Our central hypothesis is that this mapping is general across domains, and thus can be transferred from resource-rich domains to low-resource ones. Our model jointly learns a domain-invariant representation and induces the desired mapping between rationales and attention. Our empirical results validate this hypothesis and show that our approach delivers significant gains over state-of-the-art baselines, yielding over 15% average error reduction on benchmark datasets. Our code and data are available at https: //github. com/YujiaBao/R2A.
by Yujia Bao.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Narayan, Santhosh. "Applications of machine learning : basketball strategy." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123043.
Full textAbstract:
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 72-74).
While basketball has begun to rapidly evolve in recent years with the popularization of the three-point shot, the way we understand the game has lagged behind. Players are still forced into the characterization of the traditional five positions: point guard, shooting guard, small forward, power forward, and center, and metrics such as True Shooting Percentage and Expected Shot Quality are just beginning to become well-known. In this paper, we show how to apply Principal Component Analysis to better understand traits of current player positions and create relevant player features based on in-game spatial event data. We also apply unsupervised machine learning techniques in clustering to discover new player categorizations and apply neural networks to create improved models of effective field goal percentage and effective shot quality.
by Santhosh Narayan.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Yao, Li. "Magnetic field modelling of machine and multiple machine systems using dynamic reluctance mesh modelling." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/10224/.
Full textAbstract:
This thesis concerns the modified and improved, time-stepping, dynamic reluctance mesh (DRM) modelling technique for machines and its application to multiple machine systems with their control algorithms. Improvements are suggested which enable the stable solution of the resulting complex non-linear equations. The concept of finite element (FE) derived, overlap-curves has been introduced to facilitate the evaluation of the air-gap reluctances linking the teeth on the rotor to those on the stator providing good model accuracy and efficient computation. Motivated industrially, the aim of the work is to develop a fast and effective simulation tool principally for evaluating salient pole generator system designs including the generator, exciter and the automatic voltage regulator (AVR). The objective is to provide a modelling system capable of examining the detail of machine operation including saturation of main and leakage flux paths, slotting and space harmonics of the windings. Solutions are obtained in a sufficiently short computational time to facilitate efficient iterative design procedures in an industrial design office. The DRM modelling technique for electrical machines has been shown in this thesis to be a fast and efficient tool for electrical machine simulation. Predicted results for specific machine and system designs have been compared with FE solutions and with experimental results showing, that for engineering purposes, the technique yields excellent accuracy. The DRM method has a great advantage in multiple machine simulations. This is because magnetic field calculations are limited to evaluating only the most important information so saving computation time. A brushless generating system including the excitation system and control scheme has been modelled. Additionally a cascaded, doubly fed induction generator for wind generator applications has also been modelled. These different applications for the dynamic reluctance mesh method have proved that this approach yields an excellent machine and machine-system evaluation and design tool.
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Wu, Anjian M. B. A. Sloan School of Management. "Performance modeling of human-machine interfaces using machine learning." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122599.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2019, In conjunction with the Leaders for Global Operations Program at MITThesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019, In conjunction with the Leaders for Global Operations Program at MIT
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 70-71).
As the popularity of online retail expands, world-class electronic commerce (e-commerce) businesses are increasingly adopting collaborative robotics and Internet of Things (IoT) technologies to enhance fulfillment efficiency and operational advantage. E-commerce giants like Alibaba and Amazon are known to have smart warehouses staffed by both machines and human operators. The robotics systems specialize in transporting and maneuvering heavy shelves of goods to and from operators. Operators are left to higher-level cognitive tasks needed to process goods such as identification and complex manipulation of individual objects. Achieving high system throughput in these systems require harmonized interaction between humans and machines. The robotics systems must minimize time that operators are waiting for new work (idle time) and operators need to minimize time processing items (takt time). Over time, these systems will naturally generate extensive amounts of data. Our research provides insights into both using this data to design a machine-learning (ML) model of takt time, as well as exploring methods of interpreting insights from such a model. We start by presenting our iterative approach to developing a ML model that predicts the average takt of a group of operators at hourly intervals. Our final XGBoost model reached an out-of-sample performance of 4.01% mean absolute percent error (MAPE) using over 250,000 hours of historic data across multiple warehouses around the world. Our research will share methods to cross-examine and interpret the relationships learned by the model for business value. This can allow organizations to effectively quantify system trade-offs as well as identify root-causes of takt performance deviations. Finally, we will discuss the implications of our empirical findings.
by Anjian Wu.
M.B.A.
S.M.
M.B.A. Massachusetts Institute of Technology, Sloan School of Management
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Kew, Min Shen Peter. "Dynamic analysis of multi-machine electromechanical systems." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290341.
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This thesis describes the detailed modelling procedures for d-q axis representation of multi-machine electromechanical systems. It proposes two methods of connecting electrical machine models which have been formulated in various reference frames, to transmission network models. Investigation of these two methods was accomplished, and the effectiveness and merits of each are fully discussed. Conclusions are drawn which form the bases for recommendation of a connection method for developing a generalised multi-machine power system model. In addition two computer programs are written to provide means of simulating both large and limited capacity power systems on personal computers.
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Wang, Tianhao. "Self-sensing permanent magnet machine." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42541/.
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This thesis looks at the saliency-based self-sensing control of permanent magnet synchronous machines (PMSM) and a novel machine configuration is proposed to improve the self-sensing performances. In recent time, PMSM drives have been steadily gaining popularity and have widespread applications in industry due to its benefits such as high power density, good dynamic performance and high efficiency. Self-sensing drives are superior to conventional drives in applications where the reliability and the cost are of important factors. Machine saliency is utilized for rotor position tracking during the start-up and the low speed operation when Back-EMF components are not detectable. For conventional PMSM machines, however, the saliency of Interior Permanent Magnet (IPM) machine is heavily affected by saturation effects under loaded operation; for the case of Surface Mounted Permanent Magnet (SMPM) machines, the saliency is not apparent and hard to detect. Hence the rotor position signals are relatively small or even undetectable at specific operation points, and these are the main challenges of PMSM drive self-sensing controlled at the low speed. Addition of a novel saliency modulation rotor end (SMRE) structure to the end of a conventional PMSM rotor to improve the self-sensing capability is proposed. The SMRE provides an additional space anisotropic to the rotor. The saliency modulation of the rotor end is electrically asynchronous with the machine`s rotating reference frame. Therefore, the machine saliency provided by SMRE is not affected by saturation effects under loaded operation when high frequency injection scheme is adopted in low speed ranges. In addition, for the medium and high speed range, the rotor position can be tracked without superposed injection as the saliency modulation can be achieved by taking the fundamental voltage as the carrier signal. A genetic algorithms (GA) optimization environment combined with the finite element analysis (FEA) enables to obtain optimized rotor end geometry for the maximum modulation signal and minimum total harmonic distortions (THD). The expected self-sensing performance is validated by a prototype machine and is compared with conventional PMSMs in experimental tests.
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Liu, Jiuling. "A finite state machine synthesizer." PDXScholar, 1989. https://pdxscholar.library.pdx.edu/open_access_etds/3912.
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This thesis presents a Finite State Machine (FSM) Synthesizer developed at Portland State University. The synthesizer starts from a high level behavioral description, in which no states are specified, and generates the lower level FSM descriptions for simulation and physical layout generation.
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Manyage, Marubini J. "Application of improved core loss formulations to machine design." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5173.
Full textAbstract:
Includes abstract.Includes bibliographical references (p. 117-120).
The primary focus of this thesis is in core loss measurement and modeling techniques and their impact in machine design. In practice, steel manufacturers usually supply core loss data either at 50/60Hz, 1.5T or curves (core loss vs. flux density) at 50 and/or 60Hz. There is growing need for lamination characterization at high flux densities (2T) and high frequencies (3.2 kHz) for novel electric machine designs operating at high speeds. The core loss measurement concept is reviewed first. Two core loss measurement formulae are compared using core loss results from different testing frames and materials.
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Bartleet, Trevor Clive. "Real-time automatic machine inspection of plastic bottle closures." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/9643.
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Bibliography: leaves 89-91.This thesis presents work done developing an automatic system for plastic bottle closures. These plastic closures ae manufactured at 20 per second and the inspection must be done in real-time at this rate. Two types of defects must be detected and the defective closures removed from the production line. Inspection by human operators proved to be unreliable and subjective, and an automatic inspection system was needed. A machine vision system is capable of producing reliable and repeatable results in an environment which is unpleasant to humans. An automatic inspection system was implemented on the production line. The development of this system is divided into three sections.