Dissertations / Theses on the topic 'Electrical machine design'

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.

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.

Pages 6-12 missing.
Thesis (MScEng)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: The transverse flux machine (TFM) offers the opportunity of high torque to volume ratios which makes it an excellent candidate for direct wheel drives and low speed generator applications. TFMs have a three dimensional flux path which eliminates iron laminates as a viable core material. Soft magnetic composites have been adopted in these machines due to their isotropic nature. There are three main variants of TFMs, namely, active rotor (with magnets on the rotor), passive rotor (with magnets on the stator), and reluctance (with no magnets). As a relatively recent development in electrical machines, the TFM still has many hurdles facing its adoption in industry. Some of these hurdles are high cogging torque, a difficult construction, and expensive materials. This thesis focuses on the design of a three phase 50 kW passive rotor machine. Finite element simulation is used to determine the optimal configuration, and the final machine is analysed in detail. The construction process and associated problems are also detailed. The completed machine did not perform to the desired specification, but much knowledge was gleaned about the TFM, the construction caveats, and future potential directions.
AFRIKAANSE OPSOMMING: Die transversale-vloed masjien (TFM) met sy hoe draaimoment tot volume verhouding, is 'n uitstekende kandidaat vir direkte wiel aandrywing en lae spoed generator toepassings. Die vioed pad van die masjiene is drie-dimensioneel, wat yster laminasies as kern materiaal elimineer. "Soft magnetic composites" kan gebruik word vir hierdie masjiene as gevolg van hulle isotropiese eienskappe. Daar bestaan drie hoof variante van die TFM, naamlik, die aktiewe rotor (met magnete op die rotor), passiewe rotor (met magnete op to stator), en reluktansie (sonder magnete). Die TFM is 'n redelike nuwe tipe masjien en daar is nog probleme wat opgelos moet word voordat die industrie sal begin om dit te gebruik. Van hierdie probleme is "cogging" draaimoment, 'n moeilike konstruksie en duur materiale. Die fokus van hierie tesis is op die ontwerp van 'n 50 kW drie-fase passiewe rotor masjien. Eindige element simulasie is gebruik om die optimale konfigurasie te kry, en 'n analise is gedoen op die finale masjien. Die konstruksie proses en die probleme wat daarmeer saam gaan is ook beskryf. Die prototipe masjien wat gebou is het nie aan sy oorspronklike spesifikasie voldoen nie, maar baie kennis is opgedoen oor die TFM, die konstruksie proses, en potensiele toekomende toepassings.

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.

This thesis describes the work done during the several stages of the design, analyse, manufacture and test of a high speed synchronous reluctance machine capable of delivering 5 kW at 80 krpm. In order to meet such demanding speed requirement, several multi-disciplinary design exercises have been carried out having different aims. First the influences of the speed-dependent limiting factors on the machine performance have been investigated by analytical methodologies. After the preliminary analytical design, the main challenges related with the structural and electromagnetic FE-based design refinements have been identified. A comparative study has been then presented with the purpose of identify the most effective rotor design approach in terms of performance of the final design and computational effort related for its achievement. Once the design strategy has been chosen, the advantages of considering rotor parametrization of increasing complexity are evaluated via a comparative study showing the results of several structural optimizations. This study indicated the optimal geometry to manufacture. Prior to the machine prototyping, the influence of the rotor manufacturing tolerance as well as the thermal limitations on the machine performance have been deeply analysed. Tests carried out on the prototype have essentially validated the proposed design approach. In addition, an investigative study aimed at identifying and understanding the reasons of the found discrepancy between the measured and expected performance is also reported.

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 213-230).
Due to the limited size of training data available, machine learning models for biology have remained rudimentary and inaccurate despite the significant advance in machine learning research. With the recent advent of high-throughput sequencing technology, an exponentially growing number of genomic and proteomic datasets have been generated. These large-scale datasets admit the training of high-capacity machine learning models to characterize sophisticated features and produce accurate predictions on unseen examples. In this thesis, we attempt to develop advanced machine learning models for functional genomics and therapeutics design, two areas with ample data deposited in public databases and tremendous clinical implications. The shared theme of these models is to learn how the composition of a biological sequence encodes a functional phenotype and then leverage such knowledge to provide insight for target discovery and therapeutic design.
First, we design three machine learning models that predict transcription factor binding and DNA methylation, two fundamental epigenetic phenotypes closely tied to gene regulation, from DNA sequence alone. We show that these epigenetic phenotypes can be well predicted from the sequence context. Moreover, the predicted change in phenotype between the reference and alternate allele of a genetic variant accurately reflect its functional impact and improves the identification of regulatory variants causal for complex diseases. Second, we devise two machine learning models that improve the prediction of peptides displayed by the major histocompatibility complex (MHC) on the cell surface. Computational modeling of peptide-display by MHC is central in the design of peptide-based therapeutics.
Our first machine learning model introduces the capacity to quantify uncertainty in the computational prediction and proposes a new metric for peptide prioritization that reduces false positives in high-affinity peptide design. The second model improves the state-of-the-art performance in MHC-ligand prediction by employing a deep language model to learn the sequence determinants for auxiliary processes in MHC-ligand selection, such as proteasome cleavage, that are omitted by existing methods due to the lack of labeled data. Third, we develop machine learning frameworks to model the enrichment of an antibody sequence in phage-panning experiments against a target antigen. We show that antibodies with low specificity can be reduced by a computational procedure using machine learning models trained for multiple targets. Moreover, machine learning can help to design novel antibody sequences with improved affinity.
by Haoyang Zeng
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

In order to achieve superior speed in sequencer designs over competing PLD devices, Cypress brought to market an innovative architecture, CY7C361. This architecture introduced a new kind of universal logic gate, the CONDITION DECODER (CDEC). Because there are only 32 macrocells in the chip, saving only one CDEC gate can be quite important (the well-known "fit/no-fit problem"). A problem that is related to the fitting problem of the Cypress CY7C361 chip is the SOC Minimization. Due to the limited low number of macrocells in CY7C361, a high quality logic minimization to reduce the number of macrocells is very important. The goal of this thesis is, however, more general, since we believe that CDEC can be used as a generalpurpose gate for standard cell structures with few levels, and also for new PLD structures. We depart, therefore, from the Cypress chip as a sole motivation of our work, and we present a generic logic synthesis problem of SOC minimization. In this thesis, we formulate the SOC minimization problem and present a new kind of approach using graph coloring to solve it. A Cube Splitting algorithm is also presented, whereby the input cubes are split in such a way, that the generated cubes are lower in number than the minterms, and when these cubes are used as nodes in graph coloring algorithm, gives near exact solutions. The algorithms used in the SOC minimization program, SOCMIN, have been designed for Strongly Unspecified functions, defined by ON and OFF sets, and hence finds important applications for Machine Learning and Pattern theory, where there is a high percent of don't cares. The approach to solving the covering problem, the Conditional Graph Coloring, can be used in other similar problems such as PLA minimization, or Column Minimization Problem in Curtis-like decomposition of Multi-valued Relations. We found also the Muller method very efficient for ON,OFF data representation: it can be used to extend any other single-output minimizer for incomplete functions to a multi-output one.

Over the recent years, there has been a rise in the demand for high speed and high power density machines for various applications in industry ranging from basic household power tools to the flight controls for aircrafts in the aerospace sector. This has also seen advancements in the power electronics and controls for these machines to deal with the large operating frequencies. The increase in demand for high speed machines has been driven by the industry’s requirement for cost reductions, higher robustness & higher efficiencies. This thesis aims to contribute knowledge to the design and development of a high-speed surface mounted permanent magnet machine. A numerical procedure for the detailed sizing of a high-speed surface mounted permanent magnet (SPM) machine is outlined in this dissertation. An analytical per phase model is formulated to examine the performance parameters of the machine. The analytical model is validated against results obtained from Ansys Electromagnetics Finite Element Analysis (FEA) software. The estimation of core losses in high-speed machines is also of critical importance during electromagnetic design. An immense amount of research has been conducted on the estimation of core losses in machines, however, not much has been done to cover the estimation of highspeed core losses as compared to the traditional low-speed machines. As part of the development of the high-speed machine, the numerical estimation of the highspeed core losses was examined and validation performed using FEA software. On average, there was a difference of about 3-11% between the analytical results and FEA results of the eddy current loss and hysteresis loss. These results demonstrate that the analytical method used to estimate core losses is reasonably accurate when compared to FEA results obtained from ANSYS Maxwell. The prototyping of a high-speed surface mounted permanent magnet machine is investigated. Focus is placed on the major components of the machine whilst highlighting the use of precision machining and the need to maintain high accuracy during manufacturing and assembly of the machine prototype.

Wave power is not an energy source takenadvantage of partly due to the lack of effective generatorsfor slow speeds. There is an ongoing project at the RoyalInstitute of Technology in Sweden where a transversive fluxmachine specialised for slow speeds is being developed.This paper aims to design the core of this machine toachieve high efficiency and low cost. The basic design ispresented along with the approach to the different aspectsof the manufacturing. After examining possible losses thesehave been bypassed or minimised using various methods.If this is not done properly, the losses will be too severe forthe machine to prove useful. A study of the results showthat a very high efficiency will be achieved, way superiorto that of currently existing wave power generators.

Thesis (MScEng)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: The thesis describes the optimum rotor design and performance of a 110kW Permanent-Magnet assisted (PM-assisted) Reluctance Synchronous traction Machine (RSM) using bonded permanent magnet sheets. Particular attention is given to the performance of the machine drive in the flux-weakening speed region. A detail explanation is given of the finite-element design optimisation, the basic principles of operation and the control-design of the PM-assisted RSM drive. A theoretical torque comparison of the PM-assisted RSM, the standard RSM and the induction machine is also done. The measured and calculated results of the different drives are presented and analysed in detail. It is concluded that the performance of the PM-assisted RSM in terms of torque, voltage and power factor compares favourably well with that of the induction machine in both the constant torque and flux-weakening speed regions. Furthermore, it is shown that the temperature rise of the stator winding of the PMassisted RSM is lower than that of the RSM with both machines at the same load.
AFRIKAANSE OPSOMMING: Die tesis beskryf die optimum rotor ontwerp en vermoë van 'n 110 kW Permanent- Pagnet-ondersteunde (PM-ondersteunde) Reluktansie Sinchroon Masjien (RSM) trekkrag aandryfstelsel. Spesifieke aandag word gegee aan die vermoë van die aandryfstelsel in die vloedverswakking spoedgebied. 'n Volledige verduideliking word gegee van die eindige-element ontwerp optimering, die basiese beginses van werking en die beheer-ontwerp van die PM-ondersteunde RSM aandryfstelsel. 'n Teoretiese vergelyking van die draaiumoment-vergelyking van die PM-ondersteunde RSM, die standard RSM en die induksmasjien word gedoen. Die berekende en gemete resultate van die verskillende aandryfstelsels word in detail aangebied en ge-analiseer. Dit is gevind dat die vermoë van die PM-ondersteunde RSM in terne van draairnoment, spanning en arbeidsfaktor gunstig vergelyk met dit van die induksiemasjien in beide die konstante draairnoment en vloedverswakking spoedgebiede. Verder word getoon dat die temperatuur-styging van die statorwinding van die PM-ondersteunde RSM laer is as die van die RSM, met deide masjiene by die selfde las

Thesis (MScEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The focus of this thesis is on the optimal design and evaluation of FI-PM machines to be used with a MG transmission drive-train for EV application. The machines presented are optimised using a gradient-based optimisation algorithm of the VisualDoc software together with FE software and Python scripts. Each machine is optimised for its own objective function. The focus is to reduce expensive rare earth material. High torque ripple issues of the optimised machines are solved by implementing a relatively new topology where the rotor poles/barriers are made asymmetric. The asymmetric rotor topology implemented is effective and can be used as an alternative for rotor stack skewing. PM demagnetisation and rotor deformation studies are conducted on the optimum designed machines to ensure that no PM demagnetisation on the surface of the PMs and critical rotor deformation occur. The FE performance results of the optimum designed machines are shown and discussed. One of the optimum designed FI-PM machines is manufactured and tested in the laboratory. The FE and measured results of the machine are compared and shows good correlation. The saliency performance of the optimum designed machines are evaluated as it determines its position sensorless control capability. It is shown that the saliency ratios increase linearly with load, making it favourable for position sensorless control. It is also shown that the asymmetric rotor topologies introduced a larger mutual inductance compared to their symmetric counterparts, thus higher cross-coupling is present in these rotors and therefore a higher saliency shift, which is undesirable. Two case studies are performed in order to improve saliency performance. The objective of the first case study is to improve the saliency shift by reducing the flux leakage paths in the rotor. The objective of the second case study is to optimise a FI-PM machine in order to improve the saliency ratio and -shift. The results of the two case studies are compared with the saliency performance of the other machines.
AFRIKAANSE OPSOMMING: Die fokus van hierdie tesis is op die optimale ontwerp en evaluering van veld versterking permanente magneet masjiene vir veelvoudige-rat elektriese voertuig toepassings. Die masjiene teenwoordig is geoptimeer met behulp van ’n helling-gebaseerde optimering algoritme. Elke masjien is geoptimeer vir sy eie doel funksie. Die fokus is om duur seldsame permanent magneet materiaal te verminder. Hoë wringkrag-rimpeleffek van die optimale masjiene word opgelos deur die implementering van ’n relatief nuwe topologie waar die rotor pole/vloedbarrière asimmetries gemaak word. Die asimmetriese rotor topologie wat geimplementeer is, is effektief en kan dus as ’n alternatief vir die rotor stapel skeef metode gebruik word. Permanent magneet demagnetisering en rotor vervorming studies is ook uitgevoer op die optimum ontwerpte masjiene om te verseker dat geen demagnetisering plaasvind nie en ook geen kritiese rotor vervorming nie. Die eindige-element resultate van die optimum ontwerpte masjiene word getoon en bespreek. Een van die optimum ontwerpte veld versterking permanente magneet masjiene is vervaardig en getoets in die laboratorium . Die eindige-element en gemete resultate van die masjien word vergelyk en toon goeie korrelasie. Die speek prestasie van die optimum ontwerpte masjiene word geëvalueer aangesien dit die sensorlose posisie beheer vermoë bepaal. Daar word getoon dat die speek koëffisiënt verhoog lineêr met vrag wat dit gunstig maak vir posisie sensorlose beheer . Daar word ook gewys dat die asimmetriese rotor topologie ’n groter wedersydse induktansie het in vergelyking met hul simmetriese eweknieë, dus is daar hoër kruis-koppeling teenwoordig in die rotors en dus ’n ho¨er speek skuif, wat ongewens is. Twee gevallestudies om speek prestasie te verbeter is uitgevoer. Die doel van die eerste gevallestudie is om die speek skuif te verbeter deur die vermindering van die vloed lekkasie paaie in die rotor. Die doel van die tweede gevallestudie is om ’n veld versterking permanente magneet masjiene te optimeer ten einde die speek koëffisiënt en - skuif te verbeter. Die resultate van die twee gevallestudies word vergelyk met die speek prestasie van die ander masjiene.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (p. 205-209).
by Kripa K. Varanasi.
S.M.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
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 59-61).
Biological state machines have the potential to enable a wide range of applications but until recently have been challenging to implement experimentally. To overcome this challenge, we described a scalable strategy for assembling biological state machines using recombinases. This platform enables the implementation of biological state machines with arbitrary behaviors, but the manual design of such state machines is increasingly challenging with increasing complexities. Here, we introduce RSMLab, an intuitive web-based application for creating circuits that implement state-dependent logic in living cells using our scalable state-machine framework. Through a graphical user interface, RSMLab users choose a desired state diagram, define arbitrary genes, and specify whether those genes are on or off in each state. RSMLab then returns a visualization of possible gene circuits that correspond to the user specifications. We use the RSMLab algorithm and demonstrate the circuit design process using examples of two-input, five-state and three-input, sixteen-state gene regulation programs. With the help of RSMLab, researchers can program state-dependent logic to study and program the way that cells respond to combinational and temporally distributed chemical events, without needing to be expert gene circuit engineers. We envision that biology-focused design software such as RSMLab will enable the faster, more reliable, and more accessible creation of DNA-encoded circuits for engineering complex cellular behaviors.
by Guillaume Georges Kugener.
M. Eng.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: With the current worldwide energy problems electric vehicles are set to replace conventional combustion engine vehicles. Electric vehicles with gearless in-wheel mounted brushless permanent magnet motors provide a more flexible and efficient means of vehicle propulsion but the electric motors, particularly the non-overlap stator winding type have not been fully researched. This study focuses on the selection and design of suitable in-wheel hub drive machine. Several machine topologies are evaluated and the single-sided axial flux machine is chosen. The average vehicle requirements are determined and design optimisations are carried with the aid of finite element analysis and an optimisation algorithm. A comparison of torque quality between single-layer and double-layer machines is carried out and it is found that double-layer machines have the least torque ripple and single-layer machines with un-equal teeth the best torque per ripple characteristics. A 16 kW, 30-pole 27-slot prototype machine optimised for power density is built, and it is found fitting for the application meeting the design requirements. The prototype machine is extensively tested and good agreement is found between finite element and measured results. The well known axial flux attraction forces are encountered in the prototype machine and they are overcome by suitable bearing selection and mechanical design. It is found that theoretical and measured cogging torques are inconsistent, the reason for this is that practical machines are not absolutely ideal due to material and manufacturing tolerances. Excessive rotor losses are found in the prototype machine and appropriate methods for their reduction are presented. This work does not aim to find the best in-wheel hub drive solution, but instead looks to uncover some of the technical available solutions.
AFRIKAANSE OPSOMMING: Met die huidige wêreldwye energie probleme, is elektriese voertuie bestem om konvensionele binnebrandenjin voertuie te vervang. Elektriese voertuie met ratlose binnewiel-geleë borsellose permanente magneet motors, voorsien „n meer aanpasbare en effektiewe metode van voertuig aandrywing, maar die elektriese motors, veral die oorvleulende stator winding tipe is nog nie ten volle nagevors nie. Hierdie studie fokus op die keuse en ontwerp van „n binnewiel aandryf masjien. Verskeie masjien uitlegte word geëvalueer en „n enkelkant aksiaalvloed masjien is gekies. Die gemiddelde voertuig behoeftes word bepaal en ontwerp optimalisering word uitgevoer met behulp van eindige element analise en „n optimaliserings algoritme. Enkellaag en dubbellaag masjiene se draaimoment kwaliteit word vergelyk. Die bevinding is dat dubbellaag masjiene die laagste draaimoment rimpel toon terwyl die enkellaag masjiene, met oneweredige tande, die beste draaimoment per rimpel karakteristieke toon. „n 16 kW, 30 pool, 27 gleuf prototipe masjien, wat vir drywingsdigtheid ge-optimaliseer is, is gebou en is geskik vir die toepassing en die vereistes. Die prototipe masjien is getoets en goeie vergelykings word getref tussen die eindige element analise en die gemete resultate. Die alom bekende aksiaal vloed aantrekkings kragte word in die prototipe masjien gesien en word oorkom deur die regte rollaer keuse en meganiese ontwerp. Nog „n bevinding is dat die teoretiese en gemete waardes vir die vertandings draaimoment nie ooreenstem nie. Die rede hiervoor is dat die praktiese masjien nie ideaal is in terme van materiaal en vervaardigings toleransies nie. Groot rotor verliese in die prototipe masjien is gevind en goeie metodes vir die minimering daarvan word voorgestel. Hierdie werk is nie „n soektog na die beste binnewiel aandrywings oplossing nie, maar mik eerder om sommige van die tegniese beskikbare oplossings te onthul.

Cube Calculus is an algebraic model popular used to process and minimize Boolean functions. Cube Calculus operations are widely used in logic optimization, logic synthesis, computer image processing and recognition, machine learning, and other newly developing applications which require massive logic operations. Cube calculus operations can be implemented on conventional general-purpose computers by using the appropriate "model" and software which manipulates this model. The price that we pay for this software based approach is severe speed degradation which has made the implementation of several high-level formal systems impractical. A cube calculus machine which has a special data path designed to execute multiplevalued input, and multiple-valued output cube calculus operations is presented in this thesis. This cube calculus machine can execute cube calculus operations 10-25 times faster than the software approach. For the purpose of ensuring the manufacturing testability of the cube calculus machine, emphasize has been put on the testability design of the cube calculus machine. Testability design and testability analysis of the iterative logic unit of the cube calculus machine was accomplished. Testability design and testability analysis methods of the cube calculus machine are weli discussed in this thesis. Full-scan testability design method was used in the testability design and analysis. Using the single stuck-at fault model, a 98.30% test coverage of the cube calculus machine was achieved. A Povel testability design and testability analysis approach is also presented in this thesis.

Structured Light Imaging (SLI) is a means of digital reconstruction, or Three-Dimensional (3D) scanning, and has uses that span many disciplines. A projector, camera and Personal Computer (PC) are required to perform such 3D scans. Slight variances in synchronization between these three devices can cause malfunctions in the process due to the limitations of PC graphics processors as real-time systems. Previous work used a Field Programmable Gate Array (FPGA) to both drive the projector and trigger the camera, eliminating these timing issues, but still needing an external camera. This thesis proposes the incorporation of the camera with the FPGA SLI controller by means of a custom printed circuit board (PCB) design. Featuring a high speed image sensor as well as High Definition Multimedia Interface (HDMI) input and output, this PCB enables the FPGA to perform SLI scans as well as pass through HDMI video to the projector for Spatial Augmented Reality (SAR) purposes. Minimizing ripple noise on the power supply by means of effective circuit design and PCB layout, realizes a compact and cost effective machine vision sensing solution.

Thesis: S.M., Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2017.
S.M. !c Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science 2017
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 91-94).
For an insurance company, assessing risk exposure for Property Damage (PD), and Business Interruption (BI) for large commercial clients is difficult because of the heterogeneity of that exposure, within a single client (account), and between different divisions, and regions, where the client is active. Traditional risk assessment models attempt to scale up the single location approach used in personal lines: A large amount of data is collected to profile a sample of the locations and based on this information the risk is then inferred and somewhat subjectively assessed for the whole account. The assumption is that the risk characteristics at the largest locations are representative of all locations, and moreover, that risk is proportional to the size of the location. This approach is both ineffective and inefficient. Thus our first goal is to build a better risk assessment model through machine learning based on clients' data from internal sources. Further, we define a new problem, to predict whether a specific contract would be profitable or unprofitable for the insurance company. This problem turns out to be an imbalance classification, which attracts the second half of our research efforts in this thesis. In Chapter 2, we first review related literature on state-of-the-art risk assessment models in the field of insurance. Later in the chapter we move to the imbalance classification problems and review some popular and effective solutions researchers have proposed. In Chapter 3, we describe the data structure, provide some preliminary analysis over certain attributes and discuss the preprocessing techniques used for feature construction. In Chapter 4, we propose a new model with the objective to develop a new risk index which represents clients' potential future risk level. We then compare the performance of our new index with the original risk index used by the insurance company and computational results show that our new index successfully captures clients' financial loss pattern, while the original risk score used by the insurance company fails to do so. In Chapter 5, we propose a multi-layer algorithm to predict whether a specific contract would be profitable or unprofitable for the insurance company. Simulation shows that we can accurately label more than 83 percent of the contracts on record and that our proposed algorithm outperforms traditional classifiers such as Support Vector Machines and Random Forests. Later in the chapter, we define a new imbalance classification problem and propose a hybrid method to improve the recall percentage and prediction accuracy of Support Vector Machines. The method incorporates unsupervised learning techniques into the classical Support Vector Machines algorithm and achieves satisfying results. In Chapter 6, we conclude the thesis and provide future research guidance. This thesis builds models and trains algorithms based on real world business data from a global leading insurance and reinsurance company.
by Ziyu Wang.
S.M.
S.M. !c Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Lo scopo di questa tesi è presentare alcuni metodi efficienti (dal punto di vista computazionale) per il calcolo degli effetti dovuti alle correnti parassite (eddy currents) in macchine elettriche rotanti in media tensione. Due applicazioni in particolare sono state considerate nel dettaglio. Inizialmente viene analizzato il fenomeno delle correnti parassite indotte nell'albero di motori asincroni a due poli e il conseguente effetto sulle prestazioni della macchina, focalizzandosi in particolare sul fattore di potenza. La seconda parte della tesi concentra la sua attenzione sullo studio dell'avviamento da rete di motori sincroni con rotore massiccio. Per ciascuna applicazione vengono introdotte alcune procedure di calcolo, facenti uso di opportuni modelli numerici basati sul metodo degli elementi finiti, per mezzo delle quali vengono adeguatamente calcolati i parametri dei circuiti equivalenti di macchina, tenendo conto degli effetti legati alle correnti parassite. I modelli numerici sono opportunamente definiti, in modo tale da ridurre al massimo la complessità delle geometrie e il conseguente onere computazionale. I risultati delle procedure innovative qui proposte sono confrontati con i dati provenienti da prove sperimentali sulle macchine oggetto di studio e con analoghi risultati di calcolo dedotti tramite le procedure comunemente utilizzate. Il confronto fra questi dati ha dimostrato che gli approcci di calcolo introdotti in questa tesi permettono di ottenere risultati con un elevato livello di accuratezza e una netta riduzione dell'onere computazionale.
The efficient computation of eddy-current effects in medium voltage electric machines is discussed in this dissertation. Two particular cases are considered. Firstly, the effects of shaft eddy-currents on two-pole induction motor performance is addressed, with special focus on the power factor. In the second part of the thesis the start-up calculation of a large synchronous motor with solid rotor is analyzed. For each application a special calculation procedure is introduced. These procedures adopt a set of suitable finite-element models to properly compute the machine equivalent circuit parameters that are mainly influenced by eddy-current-related phenomena. By suitably choosing finite-element models boundary conditions and excitations their geometry is simplified to the maximum possible extent, in order to reduce the computational burden. The results of the new calculation methods are compared with experimental data and with analogous results obtained from commonly-adopted calculation procedures. The comparison proves that the proposed approaches can lead to high accuracy levels with very remarkable computational savings.

The interest on rotating electrical machines adopting permanent magnets (PMs) has increased during the past few decades, representing now a fashionable design option in a number of fields as industrial processing, transportation, actuators, household appliances and power plants. The issues related to an increasing electrical energy demand and consumption, have generated a tendency to research electrical drives with high efficiency, pushing electrical machines technology to further improvements. The introduction of permanent magnets based on rare earth, experienced since the 1960's, gave a great input in the development of innovative machine topologies. On the other hand, the increase and the instability of rare earth PMs price, especially between 2010 and 2013, have directed the research of rare earth free alternatives, or machines using a smaller amount of PMs. Actually, the current trend in the industrial and academic research focused on developing high performance electric motors and generators, among different electrical machines, highlights the Synchronous Reluctance (SynRel) and the Permanent Magnet Synchronous Reluctance (PMASynRel) motors as best candidates to satisfy the future energy and efficiency requirements. This thesis is comprehensively dedicated to theoretical and experimental analysis and design of the Synchronous Reluctance (SynRel) and the Permanent Magnet Assisted Synchronous Reluctance (PMASynRel) machines. In particular, it will be focused on electrical machines which power ratings are ranging from fraction of Watts to some hundred kWatts, for vehicular traction and house-hold appliances. SynRel and PMASynRel motors exhibit many technical advantages, like simple and robust structure, high torque density, high efficiency, small space required for PMs, high degrees of freedom in the design, high operating speed range, high overload capability, low back EMF (null in case of SynRel motors), leading to a safe behavior in case of inverter failure. Furthermore, thanks to the appropriate vector control algorithm, the performance in terms of efficiency and torque become highly competitive. The subject matter covered in the thesis is organized into three Parts, each including a certain number of chapters. % At the beginning of each Part, a brief summary is proposed aiming to describe the main content of that Part, the goals and the anticipation of the main results. Part I includes seven chapters summarizing the research activities carried out during the Ph.D. period. The first six chapters are dedicated to electrical machines for vehicular traction, while chapter 7 investigate on motors for house-hold appliances. Chapter 1 is mainly introductory and meant to provide the basics information to understand which are the pros and cons and the features of the machines under study. Chapter 2 summarize the design criteria and the electrical requirements of ferrite PMASynRel machine for traction application. The electromechanical performance have been evaluated and compared, in terms of torque and power. A brief description of the electric supply system in order to accurately and efficiently manage the motor for achieving the requested performance is presented. Chapter 3 highlights the influence and benefits of using ferrite magnets on the machine performance, emphasizing the importance of a careful evaluation of the magnet volume in order to increase the performance while reducing the used quantity. Chapter 4 is devoted to the sensitivity analysis of the machine performance in terms of torque ripple with respect to the geometrical design. An optimization algorithm has been performed in order to investigate and determine a rotor geometry which maximize the torque and reduces the torque ripple. The impact of the geometrical parameters is taken into account and the sensitivity of the optimal solution to the geometry variation is pointed out. This chapter highlights the difficulty to get a robust geometry as far as the torque ripple reduction is concerned. Finally, a few experimental results on a Synchronous Reluctance motor prototype will be presented, compared with Finite Element Analysis simulations for validation. Chapter 5 deals with the design and optimization of a high speed PMASynRel motor considering the driving cycles of an electric vehicle. A procedure is employed to evaluate the most effective design area, which has to be considered for the global optimization. Both results and advantages of the adopted methodology are highlighted. Further analysis on traction machines are going to be presented in Chapter 6. A comparison between ferrite and sintered NdFeB PMASynRel, SynRel and a Surface mounted PM (SPM) machines performance is deeply investigated. Chapter 7, the last of this first part, will highlight the advantages in using SynRel and PMASynRel motors for house-hold appliances. The main purpose of this chapter is to discuss the features of these motors as a valid substitute to commercial motors actually used for washing machines application. Part II is dedicated to the analytical modeling of SynRel machines with the challenge of predicting accurately the air-gap field of the machine taking into account the effect of the rotor flux barriers. This Part is divided into two chapters. Chapter 8 explains the hypothesis on which the analytical model is based, the calculation of stator Magneto Motive Force through winding function and describes the reluctance network equivalent circuit for a SynRel motor with one and two flux barriers per pole. The computation of the parameters of the model, the air-gap flux density and finally some comparison with Finite Element Analysis are presented. In Chapter 9 SynRel motors with split-phase stator winding sets supplied by multiple inverters have been investigated as an increasingly attractive solution for fault-tolerant, rugged, magnet-free vehicle traction drives. As an extension to the previous chapter, an analytical procedure to model and simulate a SynRel motor, with a split-phase stator winding, through a magnetic equivalent circuit (MEC) technique, has been introduced. As an output, the air-gap flux density of the SynRel motor can be computed at any operating point. Part III, finally, presents some experimental measurements carried out for two prototypes of SynRel and PMASynRel machines, with the purpose of comparing the results achieved in the motor optimization presented in Chapter 7.
In questi ultimi anni l’interesse per le macchine elettriche rotanti facenti uso di magneti permanenti ha riscontrato uno sviluppo sempre pi `u crescente. Tali macchine rappresentano un mondo alternativo alle tradizionali macchine sincrone e ad induzione, e vengono considerate ad oggi soluzioni promettenti in svariati settori, come quello industriale, per il trasporto, come attuatori, elettro domestici e per l’impiego in impianti di potenza. I problemi legati all aumento della domanda di energia elettrica ed al suo consumo, hanno generato una tendenza alla ricerca di azionamenti ad alta efficienza, spingendo la tecnologia delle macchine elettriche classiche ad ulteriori miglioramenti. L’introduzione dei magneti permanenti che utilizzano terre rare, gia dagli anni 60, hanno incentivato e permesso lo sviluppo di diversi tipi di macchina innovativi. Tuttavia, l’aumento e l’instabilita del prezzo delle terre rare, tra il 2010 ed il 2013, ha diretto la ricerca verso soluzioni di macchine alternative senza magneti permanenti, o con una quantita ridotta di tali materiali, pur soddisfando le specifiche di progetto. Al momento, la ricerca industriale e quella accademica sono entrambe focalizzate allo sviluppo di motori e generatori elettrici con elevate prestazioni, tra i diversi tipi di macchine elettriche esistenti, i motori sincroni a riluttanza (SynRel) ed a riluttanza assistita da magneti permanenti (PMASynRel) risultano essere degli ottimi candidati per il soddisfacimento delle specifiche energetiche e di efficienza, sempre piu stringenti, che verranno richieste ai motori nel prossimo futuro. Questo lavoro di tesi e interamente dedicato all’analisi teorica e sperimentale ed alla progettazione di motori sincroni a riluttanza (SynRel) e motori sincroni a riluttanza assistita da magneti permanenti (PMASynRel). In particolare, l’attenzione sar`a p osta su macchine elettriche in un campo di potenza che varia dalle centinaia di Watt alle decinedi kiloWatt, principalmente per applicazioni come veicoli elettrici ed elettro domestici. Tali macchine presentano una serie di vantaggi tecnologici che le portano ad avere prestazioni, soprattutto nel campo degli azionamenti a velo cit`a variabile (VSD), competitive rispetto ad esempio alle macchine ad induzione tradizionali o quelle a magneti permanenti. La struttura semplice e robusta, l’utilizzo ridotto di magneti permanenti, i gradi di liberta nella progettazione combinate ad un’elevata densita di coppia, alta efficienza elevate caratteristiche di sovraccarico ed un ampio campo di velocita, sono tutte caratteristiche che hanno permesso di collo care le macchine SynRel e PMASynRel in una posizione di rilievo. Inoltre, grazie all’aumento dei convertitori moderni a frequenza variabile e sistemi di controllo digitale, le prestazioni di questo tip o di motori, in termini di coppia ed efficienza, sono diventate altamente competitive rispetto ai tradizionali azionamenti con motori ad induzione.

Cette thèse présente le dimensionnement d’une machine électrique à rotor disque pour la traction de véhicules hybrides. Un état de l’art complet sur les machines électriques à rotor disque permet de montrer que la machine à flux axial à rotor central est la plus adaptée. Différentes géométries du circuit magnétique sont successivement étudiées et comparées par simulations par éléments finis. Pour maximiser le rendement de la machine, les pertes d’origine électromagnétique sont étudiées. Un modèle analytique des pertes par effet de peau dans les conducteurs de cuivre est proposé et validé par éléments finis. Un second modèle analytique estime les pertes par courant induits dans les aimants permanents pour tous les points de travail de la machine se basant sur uniquement trois simulations par éléments finis permettant ainsi un gain de temps important lors du dimensionnement. Deux méthodes de dimensionnement sont comparées : le dimensionnement manuel par essais/erreurs et l’optimisation multi-objectifs. Cette dernière méthode automatise le dimensionnement et permet une optimisation plus pointue et une forte amélioration des performances. Dans ce cas, la densité de couple a par exemple été augmentée de 29%. La machine à flux axial dimensionnée est comparée avec une machine à flux radial pour véhicules hybrides. Cette comparaison révèle le potentiel de la machine à flux axial avec notamment une densité de couple augmentée de plus de 20%. Enfin, deux prototypes ont été construits et mesurés pour valider les simulations
This PhD presents the design of a disc rotor electric machine for the traction of hybrid vehicles. A complete state of the art enables the selection of the internal rotor axial flux machine which is the most suited to this application. Different geometries of the magnetic circuit are successively studied and compared with finite elements simulations. To maximize the efficiency of the machine losses generated in the magnetic circuit are studied. An analytic model on the skin effect in the copper conductors is proposed and validated with finite elements simulations. A second analytic model estimates the eddy current losses in the permanent magnets for every operating point of the machine based on only three finite element simulations enabling an important time-saving. Two dimensioning methods are compared: the manual dimensioning based on a tries/errors method and the multi-objectives optimization. This last method automates the dimensioning and enables a more refined optimization and a strong improvement of the performances. For example, the torque density has been improved by 29% in that case. The designed axial flux machine is compared to a state of the art radial flux machine for hybrid vehicle. This comparison shows the potential of the axial flux machine with an improvement of the torque density by more than 20%. Finally two prototypes have been built and measured to validate the simulations

This thesis deals with the analysis, design and test of three-phase high efficiency electrical motors, with particular reference to motors with a rotor winding. At first, the background and the motivations of this work are described. The bibliography on the subjects is deeply examined and a selection of the most relevant papers can be found in the reference. In this scenario, the main objective of this thesis are illustrated. The Line-Start (LS) Synchronous Machine (SyM) design is a subject under investigation since the beginning of the last century, when solid state power converters was not available to drive SyMs. The LS SyM diffusion was limited by the intrinsic difficulties in its design and by the availability of the cheaper and more robust Induction Machine (IM). The working principle of IM and LS SyM are briefly described, as well as the state of the art of the techniques of analysis. Recently, there is a renewed interest on LS SyMs due to the new efficiency requirements and fast analysis techniques are required for the LS SyM design. A Finite-Element (FE) aided analytical model is developed to simulate the LS SyM dynamic. The aim is to develop a model that gives reliable solutions with limited computational efforts compared with other analysis techniques. With this procedure, the LS SyM rotor parameters can be quickly calibrated to fulfill the dynamic load requirements. An innovative analysis technique of LS SyM steady state condition is described. Such an analysis is carried out in the same reference frame used for classical SyMs. It is shown that the analysis can be used to optimize some machine parameters. The issues in LS SyM manufacturing are introduced, with particular reference to the die casting process. The possibility to apply the recent improvements in the SRM design to LS SyM is discussed from the manufacturing point of view. Stochastic optimization has been adopted for the design of electrical motors to reduce the torque ripple, increase the average torque and reduce the losses. The LS SyM torque ripple reduction, achieving at the same time a high average torque, is an important issue even though this topic is not treated extensively in the literature for LS SyM. For this reason, a stochastic optimization is considered in this thesis for the design of a new LS SyM lamination. The analysis is applied on a small size, 2-pole, three-phase LS SyM as this category is still not found in the motor market. The optimization is carried out considering the necessity to achieve a robust design, suitable for the industrial production, as such a LS SyM must be competitive with the workhorse of electrical motors, the IM. One of the most promising design is prototyped. Its performance are compared with the corresponding IM. To demonstrate the feasibility in adopting LS SyM in the large-scale production, an innovative LS SyM design is proposed. The main aim is to use the same lamination for motors of different number of poles so as to reduce the manufacturing cost. A tradeoff between contrasting aspects is necessary in the design step. The performance achievable by these rotor structures are quantified. An analytical model that describes the mutual interaction between coupled electrical circuits in machines with complex rotor structure is developed. Such a model is useful to analyze the parasitic torques in the torque characteristic of motors with rotor cage such as IM and LS SyM. The literature reveals that this topic has been discussed extensively for IM. As regards LS SyM, there is a lack of theoretical studies regarding harmonic phenomena due to the complex machine structure. This part of the thesis aims to fill this gap. The high and unstable cost of rare-earth PMs, together with the advances in solid-state control technology, leads designers to reconsider IM for variable speed drive (VSD) applications. To the aim of making the IM suitable for the full-speed sensorless control, a particular cage design is considered. An intentionally created saliency is introduced in the rotor so as to allow the rotor position to be estimated by means of a high frequency (HF) injected signal in the stator winding also at zero-speed. Different experimental tests are carried out on IMs with asymmetrical rotor cage to validate the analysis techniques and quantify the achievable performance. As far as the HF signal injection sensorless technique is concerned, the cross-saturation differential inductance of SyMs represents an issue. It causes a rotor position estimation error, reducing the region in which such technique is effective. The proper-ties of the cross-saturation inductance are deeply discussed. It is originally shown that the cross-saturation inductance depends from certain machine parameters. With such an analysis, a designer can consider the effect of the cross-saturation inductance in any model-based control algorithm. A rotor winding is added in Surface-mounted permanent-magnet machine (SPM) to create a HF anisotropy that is useful to detect the rotor position by means of a HF signal injection. Such a configuration is called ”ringed-pole”. In literature, this technique has been used on small-size machines. In certain configuration, the presence of the additional rotor winding causes significant rotor losses. This part of the thesis studies the rotor losses in ringed pole machines by means of FE analysis and analytical models. The aim is to investigate if the ringed-pole technique can be adopted also for large machines from the point of view of additional losses. With few exceptions, the work described in this thesis is always supported by means of experimental measurements. Dedicated experiments has been designed. Their results are compared with those achieved with analytical models or FE analysis.
Questo lavoro di tesi è incentrato sull’analisi, la progettazione e la prototipazione di macchine elettriche trifase ad alto rendimento, con particolare riferimento a motori dotati di avvolgimenti rotorici. Inizialmente si descrivono le motivazioni di questo lavori di tesi e il contesto in cui essa si inserisce, illustrandone i principali obiettivi. Una dettagliata analisi bibliografica è alla base del lavoro svolto. Una selezione di questi lavori si trova nelle referenze. I motori sincroni autoavvianti (LS SyM) sono stati introdotti nella prima metà del novecento e la loro progettazione è soggetto di ricerca sin da allora. Essi non si sono mai affermati a causa della loro difficile progettazione e per la disponibilità del più robusto ed economico motore ad induzione (IM). Dopo aver descritto il principio di funzionamento di IM e LS SyM, se ne illustrano le tecniche di analisi sviluppate fino al giorno d’oggi. Negli ultimi anni vi è un rinnovato interesse verso i LS SyM grazie agli stringenti requisiti di rendimento. Vi è quindi la necessità di tecniche di progettazione veloci ed affidabili per LS SyM. I risultati di simulazioni agli elementi finiti sono stati combinati a modelli analitici per descrivere la complessa dinamica di LS SyM. L’obiettivo è quello di ottenere una risposta sufficientemente precisa in tempi molto più brevi rispetto ad altre tecniche di analisi. In questo modo si rende possibile una rapida e precisa calibrazione dei parametri rotorici necessari per soddisfare determinati requisiti di carico dinamico. Parte di questa tesi è dedicata allo sviluppo di una tecnica di analisi per LS SyM in condizioni di regime. Tale analisi `e condotta nello stesso sistema di riferimento usato nei classici modelli per macchine sincrone non autoavvianti. Si mostra che l’analisi proposta permette anche di ottimizzare alcuni parametri di macchina. Negli ultimi anni vi sono stati numerosi sviluppi nella progettazione di macchine sincrone a riluttanza, con o senza l’assistenza di magneti permanenti. In questa tesi si è voluto investigare sulla possibilità di applicare tali sviluppi ai LS SyM, tenendo in considerazione i vincoli costruttivi legati alla presenza della gabbia rotorica. Lo scopo è quello di ridurre il volume di magneti permanenti utilizzati per contenere i costi di produzione. Si è affrontato il problema dell’industrializzazione dei LS SyM, con particolare riferimento al processo di pressofusione del rotore. Nell’intento di ridurre il ripple di coppia, incrementare la coppia media e ridurre le perdite dei motori elettrici, recenti lavori propongono l’utilizzo di algoritmi di ottimizzazione stocastica nella fase di progettazione. I suddetti obiettivi sono basilari anche per LS SyM, anche se per questo tipo di motori la letteratura è meno fornita. Per questo motivo si è voluto utilizzare un algoritmo di ottimizzazione nella fase di progettazione della lamiera di un LS SyM. L’analisi è applicata ad un LS SyM trifase a 2 poli di piccola taglia, dato che ancora non si trovano nei cataloghi dei principali costruttori. L’ottimizzazione è sviluppata considerando la necessità di ottenere un progetto robusto e comunque adatto alla produzione industriale, dato che tale LS SyM deve essere competitivo con l’ormai consolidato IM. Una promettente struttura rotorica è stata prototipata. Le prestazioni ottenute sono confrontate con quelle del corrispondente IM. Si è proposta un innovativa configurazione di LS SyM per dimostrare la fattibilità del loro utilizzo su scala industriale. Lo scopo è quello di utilizzare la stessa lamiera per motori con un diverso numero di poli, riducendo di conseguenza il costo di produzione. Per fare ciò è necessario un compromesso tra aspetti contrastanti nel progetto. In questa parte di tesi, si è voluto quantificare le prestazioni ottenibili da tali geometrie nelle diverse configurazioni. In questa tesi si è sviluppato un modello analitico per caratterizzare l’interazione di circuiti elettrici accoppiati in strutture complesse quali quelle dei LS SyM. Questa analisi mira ad essere uno strumento per la determinazione analitica delle coppie parassite in motori dotati di gabbia rotorica come LS SyM e IM. La letteratura riporta un gran numero di lavori riguardanti la descrizione di coppie parassite nella caratteristica di coppia di motori IM. In LS SyM, l’analisi delle coppie parassite è molto più complessa a causa della struttura di macchina. In letteratura, gli studi analitici riguardanti gli effetti di armoniche di MMF in motori LS SyM sono pochi ed incompleti. L’elevato ed instabile prezzo dei magneti permanenti, assieme allo straordinario sviluppo dell’elettronica allo stato solido, ha spinto a riconsiderare il motore ad induzione per applicazioni a velocità variabile. In questo scenario, si è considerato un avvolgimento rotorico a gabbia di scoiattolo in cui i conduttori sono asimmetrici. Tale asimmetria permette il riconoscimento sensorless della posizione rotorica tramite iniezione di segnali ad alta frequenza negli avvolgimenti di statore anche a velocità molto basse. Sono stati condotti test sperimentali su prototipi di IM con gabbia asimmetrica allo scopo di verificare le tecniche di analisi e di quantificare le prestazioni ottenibili da tali geometrie. Proseguendo l’analisi delle problematiche riscontrate in controlli di tipo sensorless con iniezione di segnale, si sono approfondite le proprietà della mutua induttanza differenziale causata dal fenomeno della saturazione incrociata tra asse d e q in macchine sincrone. Essa causa un errore nella stima della posizione rotorica, riducendo di fatto l’applicabilità del controllo sensorless con iniezione di segnale. Dopo aver discusso in dettaglio le propriet`a di tale induttanza, si `e dimostrato che essa dipende da alcuni parametri di macchina. Con i risultati ottenuti, può essere intrapresa una serie di accorgimenti nel controllo della macchina volta a mitigare l’effetto negativo dell’induttanza mutua dovuta alla saturazione incrociata. Uno o più avvolgimenti rotorici possono essere introdotti anche in motori sincroni a magneti permanenti superficiali, allo scopo di estendere l’applicabilità del controllo sensorless con iniezione di segnale anche a questo tipo di motori. In questo tipo di macchine, denominate ”ringed-pole”, tali avvolgimenti rotorici possono essere sede di perdite importanti nel funzionamento a regime. In letteratura, questa tecnologia è stata applicata a motori di piccola taglia. In questo contesto, si sono studiate le perdite rotoriche di macchine ”ringed-pole” tramite analisi agli elementi finiti e modelli analitici. Lo scopo è quello di verificare se l’uso di tale tecnologia può essere esteso a macchine di taglia superiore dal punto di vista delle perdite rotoriche. Con poche eccezioni, gli argomenti di questa tesi sono validati tramite misure sperimentali. I risultati delle prove sperimentali sono confrontati con quelli provenienti da modelli analitici o da analisi agli elementi finiti.

Includes bibliography.
The objectives of the project were firstly, to propose and implement the hardware needed for a Machine Vision System that is to operate on the Spiral Ore Concentrator. Secondly, to propose and implement an algorithm that would operate together with the hardware, to find the transition point between the two types of material, also to find the optimum position for the blade separator, while the system operates in a continuous repetitive mode. Finally, to have an on line analysis of the efficiency of the refinement process in the Spiral Ore Concentrator. The hardware of the Machine Vision System was implemented and tested in the laboratory. The hardware included a video recorder, through which a video signal was obtained from the play-back of video material taken of the ore flow in the Spiral Ore Concentrator. The video signal was used as input to an RGB decoder in order to remove the colour modulation. A black and white frame grabber digitized the video signal which was then analyzed by a computer. Based on the fundamental theory of edge detection used in computer vision systems, an algorithm was designed and implemented to detect the transition point between the two types of material. This algorithm was used to find the difference of averages of grey levels between two global neighborhoods within a specified area of interest window. The algorithm gave consistent results and was robust towards surface irregularities. The algorithm, operating in a continuous repetitive mode, gave rapid fluctuations in the determined edge position. Because a motor with a slow response time would be used to control the movement of the blade separator, the determined edge position signal was smoothed by a filter. Based on periodogram analysis of the edge position signal, a smoothing filter was implemented which incorporates a median filter, followed by a fading-memory polynomial filter. These filters gave sufficient smoothing with little lag to step changes in ore concentration. The efficiency of the ore separation was monitored by the determination of losses. These losses consist of, the percentage of black material loss and percentage of white material contamination. Two types of losses could be identified, they were Spraying losses and Filter losses, these were combined to give Total losses. From the true edge position curve, which was obtained by finding the edge position every second pixel point, the Nyquist sampling frequency could be determined. Because of the slow sampling rate, an error in the calculation of the losses was determined from the true edge curve, and the sub-sampled edge curve. Based on this error, it was shown that the machine vision system could multiplex multiple camera inputs.

This thesis reports the performance of a simple classifier as a function of its training data set. The classifier is used to remove analog tests and is named the Test Removal Classifier (TRC). The thesis proposes seven different training data set designs that vary by the number of wafers in the data set, the source of the wafers and the replacement scheme of the wafers. The training data set size ranges from a single wafer to a maximum of five wafers. Three of the training data sets include wafers from the Lot Under Test (LUT). The training wafers in the data set are either fixed across all lots, partially replaced by wafers from the new LUT or fully replaced by wafers from the new LUT. The TRC's training is based on rank correlation and selects a subset of tests that may be bypassed. After training, the TRC identifies the dies that bypass the selected tests. The TRC's performance is measured by the reduction in over-testing and the number of test escapes after testing is completed. The comparison of the different training data sets on the TRC's performance is evaluated using production data for a mixed-signal integrated circuit. The results show that the TRC's performance is controlled by a single parameter- the rank correlation threshold.

Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program, 2017.
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 107-112).
Pulmonary diseases are responsible for more than 15% of deaths worldwide. Much of this burden is concentrated in the developing world, where these diseases cause 19% of deaths. In much of the developing world, pulmonary diseases are under-diagnosed and misdiagnosed because the correct equipment is not available or health care is provided by workers with insufficient training. To help improve the diagnosis of pulmonary disease, we built a pulmonary diagnostic kit that consists of an electronic stethoscope, an augmented reality peak flow meter, and an electronic questionnaire. Using this kit, we collected data from patients who visited the Chest Research Foundation, a pulmonary clinic in Pune, India. Using the data collected from these patients, we pursued several of avenues of research. First, we trained algorithms to automatically detect two adventitious breath sounds: wheezes and crackles. We used two approaches to detect these sounds: traditional signal processing methods and new techniques from deep semi-supervised learning. Both techniques showed moderate success at identifying wheezes and crackles. Second, we evaluated the diagnostic potential of detecting wheezes and crackles and compared it to using signal processing analysis of lung sounds to directly detect pulmonary disease. We showed that this new technique leads to improved diagnostic accuracy. This finding indicates that future research should focus less on lung sound identification. Third, we combined measurements from all three components of our kit to predict the diagnosis of patients with pulmonary disease. We showed that most of the diagnostic accuracy of the kit was provided by the peak flow meter and questionnaire combination. Together, these two devices were able to accurately detect patients with asthma and COPD. After developing the diagnostic algorithms, we built an Android application to guide a user through the necessary data collection to arrive at a diagnosis. The application was designed to create questionnaires and data queries from an externally defined model definition file, allowing the application to be easily repurposed for different classification tasks in medicine and other fields. Future research will expand the use of the pulmonary diagnostic kit to include additional pulmonary diseases and will test its use in a large-scale field study to determine its accuracy as a screening tool for asthma and COPD. If the results of future trials are consistent with the findings in this thesis, the kit and algorithm combination may provide useful information for improving diagnosis of pulmonary disease.
by Daniel Chamberlain.
S.M. in Technology and Policy
S.M.

Technological advances in the aerospace industry have improved aircraft efficiency and reduced the cost of air transport, leading since 1960 to a continuous growth of the worldwide air traffic. Today it is postulated that also into the foreseeable future both the passenger and cargo air traffic will continue to growth, increasing the CO2 air transport emissions. In this contest, there are many environmental as well as commercial pressures on aircraft manufacturers to improve performances of future aircraft in terms of safety, air pollution, noise and climate change. To achieve these goals, it is necessary revisiting the whole aircraft architecture system, with the introduction of new technologies for performing key functions on aircraft. Today the conventional civil aircraft are characterized by four different secondary power distribution systems: mechanical, hydraulic, pneumatic and electrical. This implies a complex power distribution nets aboard, and the necessity of an appropriate redundancy of each of them. In order to reduce this complexity, with the aim to improve efficiency and reliability, the aerospace designer community trend is towards the `More Electric Aircraft (MEA)' concept, that is the wider adoption of electrical systems in preference to the others. This solution involves an increase of the aircraft electrical loads and, as a consequence, heavy implications for the on-board electrical generation systems are predictable. The resulting increase of the electrical power requirements encourage the research of alternative solutions rather than simply scaling up existing technologies such as generators driven by gearboxes. To address these challenges, many studies are in the direction of the so called `More Electric Engine (MEE)', in which the electrical machines are integrated inside the main gas turbine engine to generate electrical power, start the engine and guarantee safety generation in case of a critical on-flight failure. In this way the mechanical gearbox which connects the actual generators to the aeroengine shaft can be eliminated. The MEA and the MEE concept can be considered as an evolutionary implementation of the `All Electric Aircraft (AEA)', in which all the aircraft on-board systems are supplied in an electrical form. The MEE concept will involve important mechanical and thermodynamic implications in the aeroengine design, making necessary a preliminary system analysis on today conventional aeroengine, in order to evaluate the integration feasibility with the actual mechanical and environmental constraints. The electrical machines can be integrated inside the engine in some different positions, either in the front part before the combustion chamber, in particular in the low-pressure or in the high-pressure compressor stages, or in the rear part of the engine, in the tail-cone zone. In the frame of the GREAT2020 (GReen Engine for Air Transport in 2020) project co-founded by Regione Piemonte, aimed to the development of new eco-compatible aircraft engines for the entry into service in 2020, the MEE concept focus is on the evaluation of the most suitable solution between four possible integration positions in the front part of the today conventional two-shaft GEnx turbofan engine. The rotational speeds and the maximum available volumes are respectively imposed by the shaft connection and by the available spaces inside the aeroengine. In the purpose of the MEE concept on which the work presented in this dissertations is based, in order to evaluate the less critical solution between the proposed, a trade-off study conducted on preliminary electromagnetic design has been performed considering both radial and axial flux surface mounted permanent magnet synchronous machines. The comparison of the different solutions have been done on the base of same sizing indexes. Due to the particular application in which the electrical machine integration is involved, in order to evaluate impact on the whole system performance, a wider trade-off study concerning the overall aeroengine system has been done by the aerospace company Avio, partner of the GREAT2020 project. The focus of the work presented in this dissertation, is the development of appropriate tools to perform a preliminary electromagnetic design of radial and axial flux, surface mounted, permanent magnet synchronous machines with three-phase distributed and single-layer fractional-slot non-overlapping concentrated windings. In particular, this latter winding topology has been considered for its specific application for its shorter end-winding connections respect to the distributed layout, and for their high fault tolerant capability due to the electrical and physical separation between the phases which reduces the possibility of a fault propagation. Regarding the radial flux topologies, both inner and outer rotor machine structures have been considered; for the axial flux machines the single-stage (one stator and one rotor) as well as the multi-stage structures, obtained connecting on the same axis more than one single-stage structure, have been considered. The developed general purpose tools are based on simple geometrical approach using conventional design equations. The geometrical dimensions are computed starting from the design specifications and material utilization indexes imposed by the designer. The implemented codes would be a useful tool for the electrical machine designer in order to quickly define a preliminary electromagnetic design starting from a fresh sheet of paper. The conducted comparisons with commercial software have proved the validity of the tools for the conducted MEE trade-off study; however, in a prototype design aimed to the construction, detailed analysis using commercial software available on the market and Finite Element Method analysis have to be done in order to verify and improve in details the preliminary electromagnetic design obtained by the implemented codes.

Electrical and Electronic Engineering
This dissertation investigates the application of digital image processing techniques in the development of a machine vision system that is capable of characterising the froth structures prevalent on the surface of industrial flotation cells. At present, there is no instrument available that has the ability to measure the size and shape of the bubbles that constitute the surface froth. For this reason, research into a vision based system for surface froth characterisation has been undertaken. Being able to measure bubble size and shape would have far reaching consequences, not only in enhancing the understanding of the flotation process but also in the control and optimization of flotation cells.

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, Engineering and Management Program, 2015.
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 150-154).
It is common practice in organizational research to apply policy analysis to better understand how an enterprise is approaching and addressing a particular topic of interest. The approach to policy analysis commonly used is known as the Coding Approach. The Coding Approach is a highly qualitative process that involves the manual identification of relevant policy documents, the manual review of these documents to identify the key features of the topic, and the manual identification of the significance of these features as it relates to the policy documents. This process can generates rich insights into policies and how the topic of interest is being approached and viewed by the Stakeholder of the enterprise. This process however is a manually intensive process and is subject to the bias of the expert/s reviewing and analyzing the documents. My study proposes a new approach towards policy analysis that uses the Coding Approach as its template, but applies Machine Learning Techniques, such as Natural Language Processing and Data Mining Algorithms, together with a highly structured form of Case and Cross Case Analysis to identify documents that are related to the topic of interest, to categorize these documents, to surface the key features of the topic, to calculate the significance of these features as reflected by the documents and to draw inferences about the key features and its significance as it relates to the policy documents. This new approach provides a mixed methods approach that marries the best of both quantitative and qualitative techniques towards document analysis. This approach also reduces the amount bias that can be injected from the experts analyzing the documents, and thus guarantees an almost consistent result from document analysis regardless of the experts performing the analysis. For my study I applied my mixed methods approach to analyzing the policy documents of the Military Health Enterprise MHS, to understand how well the MHS 's policies were addressing the delivery of psychological services to service members and their families. This study is important to the MHS for two reasons. With the reductions of the US Military presence in Afghanistan and Iraq there are large numbers of veterans returning who may have various forms of PTSD, who will requires varying types and levels of care. The other reason why this study is important to the MHS is due to the recent scandals (Walter Reed, 2007 & VA, 2014) it has faced specifically around to the health care services it was supposed to provide to service members. Now its crucial for the MHS to understand the disconnect between its policies and what's actually being implemented. This study will provide the MHS with a non-bias review of what are the features of significance from a policy point of view in regards to the delivery of psychological services to service members and their families.
by Jaya Prasad Plmanabhan.
S.M. in Engineering and Management
S.M.

As the major electricity consumer, electrical machines play a key role for global energy savings. Machine manufacturers put considerable efforts into the development of more efficient electrical machines for loss reduction and higher power density achievements. A consolidated knowledge of the occurring losses in electrical machines is a basic requirement for efficiency improvements. This thesis deals with iron losses in electrical machines. The major focus is on the influences of the stator core magnetic material due to the machine manufacturing process, temperature influences, and the impact of inverter operation. The first part of the thesis gives an overview of typical losses in electrical machines, with focus put on iron losses. Typical models for predicting iron losses in magnetic materials are presented in a comprehensive literature study. A broad comparison of magnetic materials and the introduction of a new material selection tool conclude this part. Next to the typically used silicon-iron lamination alloys for electrical machines, this thesis investigates also cobalt-iron and nickel-iron lamination sheets. These materials have superior magnetic properties in terms of saturation magnetization and hysteresis losses compared to silicon-iron alloys. The second and major part of the thesis introduces the developed measurement system of this project and presents experimental iron loss investigations. Influences due to machine manufacturing changes are studied, including punching, stacking and welding effects. Furthermore, the effect of pulse-width modulation schemes on the iron losses and machine performance is examined experimentally and with finite-element method simulations. For nickel-iron lamination sheets, a special focus is put on the temperature dependency, since the magnetic characteristics and iron losses change considerably with increasing temperature. Furthermore, thermal stress-relief processes (annealing) are examined for cobalt-iron and nickel-iron alloys by magnetic measurements and microscopic analysis. A thermal method for local iron loss measurements is presented in the last part of the thesis, together with experimental validation on an outer-rotor permanent magnet synchronous machine.

QC 20140516

Permanent magnets play a key role as a component in a wide range of devices utilised by many industries; they are widely used in several electromechanical applications to convert energy, including actuators, motors and sensors, home appliances, office automation equipment, speakers, aerospace, wind generators and more. Traditionally the adopted PMs were obtained from Rare Earth components, such as NdFeB, with high magnetic performance, but expensive. The research of alternative permanent magnets, in many cases has brought to choose the ferrites, mainly due to their low cost, but sometimes with significant design modifications of the final circuit, and possible increment of the weight. Permanent magnets can roughly be divided into two categories: sintered (metallic) and bonded, these last representing a valid alternative to the first. Bonded magnets consist of two components: a hard magnetic powder and a non-magnetic binder; the powder may be hard ferrite, NdFeB, SmCo, and is mixed with binders for compression or injection moulding. The benefits lie in the adoption of polymeric binders to prepare the magnetic mixture: the resulting magnetic characteristic can be then “tuned” by adopting different percentages of the plastic binder. Moreover, the realisation process is simpler and cheaper than that of sintered materials, and no special protective treatment is needed. The majority of the magnetic circuits are made with soft magnetic materials. Commonly laminated steels are adopted but recently the use of Soft Magnetic Composite (SMC) materials has increased representing a new solution to design the electrical machines with respect to traditional electrical steels. SMC materials are realized with pure Iron grains coated and insulated by means of a layer that should be organic or inorganic. With respect to traditional laminated steel, these materials present different advantages: the capability to lead the magnetic flux in all directions, the volume reduction, the possibility to realize components with new complex shapes and geometries, and the reduction of iron losses, mainly the eddy currents, at medium and high frequency. On the other hand, the mechanical performances, in terms of strength, are in general weak. Furthermore, a new material typology is introduced: the Hybrid Magnetic Composites (HMC), which are obtained with a combination of soft and hard magnetic materials mixed with a binder. The basic idea is that such materials should reflect the performance of AlNiCo magnets, low coercivity and adequate remanence, typically used in sensors applications. Prototypes of traditional and unconventional rotating machines, such as assisted reluctance motors, brushless DC motors, axial flux machines and electromechanical frequency converters, have been studied in own laboratories and tested to evaluate the results coming from the adoption of the proposed materials in substitution of the commonly adopted (and expensive) Rare Earth sintered magnets. Different type of electrical machines can adopt innovative magnetic materials with the aim to improve their performance. Induction motors are very useful and robust machines; on the other hand, such type of machines does not have a high dynamic behaviour. The DC motors can be easily controlled, but the presence of the brushes causes limitations on the efficiency, thermal restrictions and reduced life. The axial flux motors (AFM) have high efficiencies but the construction of the machines is very complex. The synchronous reluctance machines (SRM) have a lower cost compared to brushless ones. In general, the reluctance electrical machines don’t use permanent magnets. In this way, they have a reduction in the costs and allow a high overload capability. On the other hand, the lower power factor and power density, compared to PM synchronous motor (PMSM), are the main disadvantages. The filling of flux barriers with the permanent magnets allows the overcoming of these drawbacks. However, the regular ferrite and NdFeB sintered magnets cannot fill the flux barriers with complex geometries. For this reason, the use of bonded magnets can be a solution for a better utilization and design of flux barriers. Therefore different prototypes have been prepared and analyzed in our laboratories using SMC materials. Several experiments have been performed using dedicated test benches, where magnetic, energetic and mechanical aspects have been considered. On the other hand, with regard to HMCs, various magnets have been made in our laboratories, and different properties have been investigated: the effect of Iron content in the material and, also the binder content effect has been analysed.

Cal Poly’s ongoing Energy Harvesting from Exercise Machines (EHFEM) project is a very convenient and cost-effective way for generating DC power from physical exercise and sending it back to the electrical grid as AC power, providing a renewable energy source for the future. The EHFEM project consists of numerous subprojects involving converting different types of exercise machines for power generation. This project is a continuation of one of the previous subprojects, specifically involving an elliptical machine, and focuses on improving system functionality at different machine settings without altering the elliptical user’s experience by selecting a new DC-DC converter design, while keeping the other system components intact. The new proposed DC-DC converter design is based on a non-isolated, PWM-switching single-ended primary inductor converter (SEPIC) topology, as opposed to the resonant zero-current switching/zero-voltage switching (ZCS/ZVS) topology-based off-the-shelf DC-DC converter that the previous project utilized, which had poor system functionality at high physical input levels (greater than 30V input) from the elliptical trainer. This project proves that a PWM-switching SEPIC topology provides a functional DC-DC converter design for DC power generation and inverter interfacing from a dynamic input voltage generator because of its wide input voltage range, high power driving capability and inherent voltage step-up and step-down functions. The proposed DC-DC converter supplies up to 288 watts of power and outputs 36 volts, and simultaneously takes 5-65 volts from its input depending on the elliptical user’s physical input level. This project details the new DC-DC converter’s design and construction processes, compares its topology to other existing DC-DC converter topologies and analyzes unfeasible designs as well as the overall system’s performance when converting the generated DC power to AC power, and documents any potential problems when used for this specific application.

Machine collaboration with the biological body/brain by sending electrical information back and forth is one of the leading research areas in neuro-engineering during the twenty-first century. Hence, Brain-Machine-Brain Interface (BMBI) is a powerful tool for achieving such machine-brain/body collaboration. BMBI generally is a smart device (usually invasive) that can record, store, and analyze neural activities, and generate corresponding responses in the form of electrical pulses to stimulate specific brain regions. The Smart Brain-Machine-Brain-Interface (SBMBI) is a step forward with compared to the traditional BMBI by including smart functions, such as in-electrode local computing capabilities, and availability of cloud connectivity in the system to take the advantage of powerful cloud computation in decision making. In this dissertation work, we designed and developed an innovative form of Smart Brain-Machine-Brain Interface (SBMBI) and studied its feasibility in different biomedical applications. With respect to power management, the SBMBI is a semi-passive platform. The communication module is fully passive—powered by RF harvested energy; whereas, the signal processing core is battery-assisted. The efficiency of the implemented RF energy harvester was measured to be 0.005%. One of potential applications of SBMBI is to configure a Smart Deep-Brain-Stimulator (SDBS) based on the general SBMBI platform. The SDBS consists of brain-implantable smart electrodes and a wireless-connected external controller. The SDBS electrodes operate as completely autonomous electronic implants that are capable of sensing and recording neural activities in real time, performing local processing, and generating arbitrary waveforms for neuro-stimulation. A bidirectional, secure, fully-passive wireless communication backbone was designed and integrated into this smart electrode to maintain contact between the smart electrodes and the controller. The standard EPC-Global protocol has been modified and adopted as the communication protocol in this design. The proposed SDBS, by using a SBMBI platform, was demonstrated and tested through a hardware prototype. Additionally the SBMBI was employed to develop a low-power wireless ECG data acquisition device. This device captures cardiac pulses through a non-invasive magnetic resonance electrode, processes the signal and sends it to the backend computer through the SBMBI interface. Analysis was performed to verify the integrity of received ECG data.

Reservoir Computing (RC) is an emerging Machine Learning (ML) paradigm. RC systems contain randomly assembled computing devices and can be trained to solve complex temporal tasks. These systems are computationally cheaper to train than other ML paradigms such as recurrent neural networks, and they can also be trained to solve multiple tasks simultaneously. Further, hierarchical RC systems with fixed topologies, were shown to outperform monolithic RC systems by up to 40% when solving temporal tasks. Although the performance of monolithic RC networks was shown to improve with increasing network size, building large monolithic networks may be challenging, for example because of signal attenuation. In this research, larger hierarchical RC systems were built using a network generation algorithm. The benefits of these systems are presented by evaluating their accuracy in solving three temporal problems: pattern detection, food foraging, and memory recall. This work also demonstrates the functionality of random Boolean networks being used as reservoirs. Networks with up to 5,000 neurons were used to 200 sequences from memory and to identify X or O patterns temporally. Also, a Genetic Algorithm (GA) was used to train different types of hierarchical RC networks, to find optimal solutions for food-foraging tasks. This research shows that about 80% of the possible different hierarchical configurations of RC systems can outperform monolithic RC systems by up to 60% while solving complex temporal tasks. These results suggest that hierarchical random Boolean network RC systems can be used to solve temporal tasks, instead of building large monolithic RC systems.