Switched reluctance motors (SRMs) are becoming popular in motor drive applications due to their simple construction, fault tolerance, and cost-effectiveness, making them well-suited for electric vehicles. However, SRMs face operational challenges at high speeds, where controller and position feedback delays may hinder smooth operation and efficiency. These challenges might limit the adoption of SRM in high-performance applications. This thesis addresses high-speed SRM control issues, focusing on delay compensation in both motoring and generating modes. Gain-scheduling PWM controller improvements and delay compensation strategies are presented to reduce the impact of position and switching delays at high-speed operation. Additionally, a four-quadrant SRM controller is proposed to enable smooth operation mode transitions and improved regenerative braking capability. A dedicated experimental setup with a three-phase 12/8 SRM connected to an electric dynamometer machine is built to validate the proposed techniques and demonstrate the improvements in the phase excitation accuracy and balance in phase currents at high speeds. The experimental results support the potential of these control methods to enhance SRM performance in high-speed applications, providing valuable insights for further improvement in electric vehicle drive train applications. / Thesis / Master of Applied Science (MASc)

In the emergence of switched reluctance motors to the commercial market, two-phase motors have received relatively little attention. Higher power and industrial applications have focused on the use of three and occasionally four phase machines, while low cost applications demanding only modest performance have largely been the domain of single phase machines. By contrast, while two phase systems have been the subject of occasional studies, they have not been widely applied. Two phase systems represent a compromise between the higher cost but higher performance three phase machines, and the lower cost but lower performance single phase systems. They do not suffer from the same magnitude of peak to peak torque ripple that single phase machines experience due to their wide zero torque arcs. Yet two phase systems keep a relatively low component count in their power-converter designs. The primary drawback to two phase motors is the difficulty of torque production at startup speeds. Although sizably reduced from single phase machines, the zero torque regions in two phase machines can still result in rotor lock unless steps are taken to circumvent them. These steps can include measures such as: placement of permanent magnets or other means to ensure the rotor is positioned outside of these zero torque regions when at rest, mechanically spinning the motor before energizing the phase windings on startup, shaping of the rotor or stator poles to extend the positive torque regions of each phase, or use of the machines mutual inductance with both phases energized to produce enough torque to initiate motion. This project is intended to develop a variable speed controller for a 4:6 two-phase switched reluctance motor. The motor is to operate in all four quadrants, and is to demonstrate self starting capability. The controller is also supposed to produce signals needed to operate the motor with multiple converter designs. Two different converter designs will be built and tested with the converter. One makes use of a single switch and two diodes per phase, the other has one switch and one diode per phase plus a common switch and common diode shared by all phases. There are many possible applications of the system being developed in this project. Any application needing four quadrant operation while still being constrained by low cost requirements would be ideal. Some examples include washing machines, power tools, and low power industrial applications. / Master of Science

The following study focuses on the design and validation of an underactuated robotic gripper built for the Tactical Hazardous Operations Robot (THOR). THOR is a humanoid robot designed for use in the DARPA Robotics Challenge (DRC) and the Shipboard Autonomous Fire Fighting Robot (SAFFiR) project, both of which pertain to completing tasks associated with disaster response. The gripper was designed to accomplish a list of specific tasks outlined by the DRC and SAFFiR project. Underactuation was utilized in the design of the gripper to keep its complexity low while acquiring the level of dexterity needed to complete the required tasks. The final gripper contains two actuators, two underactuated fingers and a fixed finger resulting in four total degrees of freedom (DOF). The gripper weighs 0.68 kg and is capable of producing up to 38 N and 62 N on its proximal and distal phalanges, respectively. The gripper was put through a series of tests to validate its performance pertaining to the specific list of tasks it was designed to complete. The results of these tests show the gripper is in fact capable of completing all the necessary actions but does so within some limitations. / Master of Science

No / The purposes of this study were firstly to investigate whether learning affects were present in the administration of 4 hop tests and the Agility T-test and secondly to assess the between-session reliability of these tests. Twenty-two recreational athletes (11 women: age 22.3 ± 3.7 years, height 167.7 ± 6.2 cm, weight 59.2 ± 6.9 kg and 11 men: age 22.8 ± 3.1 years, height 179.8 ± 4 cm, weight 79.6 ± 10 kg) took part in the study. The subjects performed 6 repetitions of each hop test and 4 repetitions of the Agility T-test once a week over a period of 3 weeks. Distances were normalized to leg length and presented as a percentage value for the single, triple and crossover hop. Results showed that there were significant differences in scores between genders and that learning affects were present in all tests. Intraclass correlation coefficients ranged from 0.76 to 0.92 for the hop tests and 0.82 to 0.96 for the Agility T-test. The results indicated that the hop and Agility T-tests are reliable tests for use with subjects in a clinical or team sport environment. The error measurement statistics presented could be of help to practitioners to determine whether changes in individuals' scores in the hop and Agility T-tests are because of a true change in performance or measurement error. Of most importance was the fact that all subjects achieved at least 90% limb symmetry index on all 4 hop tests. Therefore, we recommend that a minimum limb symmetry value of 90%, rather than previously recommended 85%, should be adopted during rehabilitation and conditioning.

Syftet med studien är att undersöka hur storbyråerna arbetar för att institutionaliserahållbarhetsgranskning i ljuset av EU:s nya hållbarhetsdirektiv CSRD. Detta görs genom enkvalitativ studie av de fyra största revisionsbyråerna på den svenska revisionsmarknaden.Data har samlats in genom semistrukturerade intervjuer med personer med en nyckelrollinom hållbarhetsgranskning på byråerna och en omfattande bearbetning av sekundära källor.Studiens resultat visar att storbyråerna arbetar för att legitimera hållbarhetsgranskningen påen rad olika sätt, inklusive genom påverkansarbete, definiering, härmning, standardisering,utbildning, skapandet av identiteter och skapandet av normativa nätverk. Genom skapandetav normativa nätverk som FAR, främjas ytterligare institutionellt arbete i form avpåverkansarbete, utbildning och standardisering. Förslag till framtida forskning är att utforskaskillnaderna i tillvägagångssätt mellan olika storbyråer när det gäller institutionellt arbete föratt legitimera hållbarhetsgranskning, med fokus på både likheter och variationer.

Bakgrund och problemdiskussion: Företag behöver anpassa sig till förändringar i omvärlden för att överleva och för att fortsätta växa. Denna typ av anpassning benämns som strategisk förändring. År 2010 avskaffades revisionsplikten för mindre bolag i Sverige. Nu, sex år senare står branschen inför ytterligare en förändring. Att revisionsverksamheten minskat och att konsultverksamheten inom revisionsbranschen kommit att ta större plats sedan avskaffandet av revisionsplikten kan tydas som en slags förändring, men hur har egentligen The Big Four som dominerar inom revisionsbranschen upplevt denna förändring? Är det en förändring som skett per automatik i samband med lagändringen eller ligger ett strategiskt agerande till grund och kan det således betraktas som att revisionsbyråerna genomgått en strategisk förändring sedan avskaffandet av revisionsplikten? När branschen står inför ytterligare en lagändring 2016 frågas hur The big Fours revisorer förväntar sig att lagändringen kommer påverka byråerna och vilken typ av förändring som revisionsbyråerna kommer genomgå i samband med lagändringen? Syfte: Syftet med uppsatsen är att redogöra för hur The Big Fours revisorer i Sverige upplever att revisions- och konsultverksamheten har påverkats sedan lagändringen 2010 samt hur revisorerna förväntar sig att revisions- och konsultverksamheten kommer påverkas i samband med lagändringen 2016, för att vidare analysera revisorernas upplevelser samt förväntningar för att bidra med kunskap om byråerna har eller kommer genomgå en strategisk förändring i samband med lagändringarna. Metod: Uppsatsen är kvalitativt uppbyggd och en flerfallsstudie har använts. Primär datainsamling har skett genom semi-strukturerade intervjuer. Respondenterna var 10auktoriserade revisorer från åtta av The Big Fours kontor. Slutsats: Uppsatsens författare har genom sitt analysarbete dragit slutsatserna att revisionsbyråerna har genomgått strategiska förändringar sedan lagändringen 2010 och att revisionsbyråerna kommer genomgå ytterligare strategiska förändringar i samband med lagändringen 2016. För att behålla sina positioner på marknaden behöver revisionsbyråerna genomgå strategiska förändringar i samband med att omvärlden ständigt förändras. / Background and problem discussion: In 2010, Sweden abolished the audit requirement for small companies. Now six years later, the industry is facing further adjustments. Companies need to adapt to changes in the environment to survive and continue to grow. This type of adjustment is referred to as strategic changes. That the audit activity is decreasing and consulting activities in the auditing industry have come to take more space since the removal of the audit requirement can be interpreted as a kind of change, but how have The Big Four that dominate the auditing profession experienced this change? Is it a change that has taken place automatically in connection with the amendment or is it a strategic action and can it thus be considered that firms have undergone a strategic change since the abolition of the audit requirement? Objective: The purpose of this thesis is to describe how The Big Four’s auditors in Sweden feel that audit and consulting business has been affected since the amendment in 2010, the auditors’ expectations of how auditing and consulting operations will be affected in connection with the amendment 2016, and to further analyse the auditors’ experiences and expectations to contribute knowledge regarding if the agencies have, or will undergo, a strategic change associated with changes in the law. Method: The essay is qualitatively constructed and multiple case study was used. Primary data collection took place through semi-structured interviews. Respondents were ten accountants from eight of the Big Four’s offices. Conclusion: The essay writers have through their analysis concluded that accounting firms have undergone strategic changes since the amendment in 2010 and that accounting firms will undergo further strategic changes in connection with the amendment in 2016. In order to maintain their positions on the market, accounting firms need to undergo strategic changes when the world is changing.

Title: The organizing and the balance between profession and profit in the Big Four accounting firms Introduction: Globalization has lead to a world with increasing similarities and a larger market where only efficient organizations survive why information is important for survival and success. Accounting firms fulfill an important role by securing information and contribute to the prosperity of society through an efficient market. But they differ both from non-PSF and among each other due to the need of managing the balance between profession and profit. The current research on accounting firms is limited and lacking. This thesis contributes to the current research by providing a new perspective to the existing research on accounting firms. Purpose: The purpose of this thesis is to understand how the Big Four accounting firms organize in order to manage the balance between profession and profit. Method: The thesis uses a qualitative research method in which data and information is collected from financial statements and websites that is compiled into multiple case studies on the Big Four accounting firms to give a detailed description of how they organize to manage the balance between profession and profit. Conclusions: The result demonstrates that there are similarities between how the Big Four accounting firms organize to manage the balance between profession and profit. The thesis moreover shows that there are connections between the factors of organizing (goal, environment, strategy and structure latter of which is divided in organizational structure, partnership, knowledge, reward system, informal and formal management processes and responsibility distribution) and the balance between profession and profit which indicates that the Big Four accounting firms considers the balance between profession and profit in the organizing for the survival and success in the market.

Thesis (M.Eng.(Mechanical and Aeronautical Engineering))--University of Pretoria, 2008. / Includes bibliographical references.

[pt] A motivação deste trabalho consiste no uso do four-roll mill para aumentar a separação de fases de emulsões água em óleo (A/O) presente no processamento primário da indústria de petróleo. A partir da conservação de massa e momento, a fase contínua foi modelada como escoamento incompressível, bi-dimensional e isotérmico. Simulações numéricas utilizando o método de elementos finitos foram implementadas para revelar a influência das diversas configurações de escoamento no comportamento mecânico do material. A partir dos resultados obtidos, a habitual forma de classificar o escoamento no four-roll mill de acordo com a literatura se demonstrou ineficiente. Este trabalho sugere classificações locais de escoamento a cada posição dependendo se a mesma está ocupada pela fase contínua ou dispersa da emulsão. O efeito da fase dispersa é descrito via pós-processamento. Microelementos no formato de vetores foram inseridos no domínio e investigou-se suas deformações e trajetórias. Consequentemente, analisou-se a deformação de gotas e a sua respectiva influência na instabilidade da emulsão. / [en] The motivation of this work consists in the use of four-roll mill in order to increase the phase separation of water-in-oil emulsions (W/O) present in the primary process of oil industry. With mass and momentum conservation, the continuous phase is modeled by an incompressible, bi-dimensional and isothermal flow. Numerical simulations employing the finite element method were implemented to reveal the influence of the several flow configurations in the material mechanical behavior. From the obtained results, the standard way of classifying the flow in the four-roll mill according to the literature was proved inefficient. This work suggests local flow classifications for each position depending if it is occupied by the continuous or dispersed phase. The effect of the dispersed phase was described by a post-processing scheme. Microelements in shape of vectors were inserted in the domain and their deformations and pathlines were investigated. Thus, the deformation of droplets and their respective influences in the emulsion instability were analyzed.

No description available.