Thesis (M.S.)--University of Michigan, 2003. / Includes bibliographical references.

Th. doct.-ing.--Énerg. phys.--Grenoble--I.N.P., 1983. N°: DI 359.

Thesis (MScEng)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: This thesis deals with the design and evaluation of a 300 kW double stage axial-flux permanent magnet generator with an ironless stator. The magnetic and electrical design equations are derived for sinewave and quasi-squarewave axial-flux permanent magnet machines. The thermal design approach used is also described. The machine is optimised for maximum torque per current loading. A Matlab program code is developed to do the necessary calculations in the design optimisation and the calculation of the machine parameters. Mechanical finite element simulations are conducted to investigate the severity of the magnetic attraction force between the rotor discs. The results obtained from the simulations suggested an increase in the yoke thickness in order to withstand the attraction force. The construction of the prototype machine's rotor and stator is described. The flux density in the airgap is thoroughly investigated through measurements and analysis. Thermal measurements are also conducted to investigate the effect of eddy currents in the stator winding. Furthermore, no-load measurements conducted on the 300 kW machine showed that the machine has a serious problem of circulating currents in the parallel connected coils. Possible solutions for this are investigated and recommendations are given. Due to the circulating current problem and the relative high eddy current losses, it was not possible to do full-load tests on the machine. / AFRIKAANSE OPSOMMING: Hierdie tesis handeloor die ontwerp en evaluering van 'n multi-stadium Aksiale Vloed Permanente Magneet (AFPM) masjien met 'n ysterlose stator. Die magnetiese - en elektriese ontwerp-vergelykings is afgelei vir sinusgolf en quasi vierkantsgolf AFPM masjiene. Die termiese ontwerp word ook bespreek. Die masjien is geoptimeer vir maksimum draairnoment per stroombelasting. Daar is 'n program-kode in Matlab geskryf om die nodige berekeninge vir die optimering van die masjien uit te voer en vir die bepaling van die masjien-parameters. Meganiese eindige element berekenings is gedoen om die invloed van die magnetiese aantrekkingskrag tussen die rotorskywe te ondersoek. Die resultate het aangedui dat die rotorskyfdikte nie die magnetiese aantrekkingskrag van die magnete kan weerstaan nie en moes in dikte vedubbel word. Die konstruksie van die masjien se rotor en stator is behandel. Die vloeddigtheid in die luggaping is noukeurig ondersoek deur metings en analise. Termiese metings is ook gedoen om die invloed van die werwel strome in die statorwikkelings te ondersoek. Verder het die nullas-toetse wat gedoen is op die masjien, aangedui dat die masjien 'n ernstige probleem het met sirkuierende strome in die parallelle geleiers van die statorspoele. Moontlike oplossings is ondersoek en aanbevelings word gegee. Dit was nie moontlik om vollastoetse op die masjien te doen nie, as gevolg van die probleem met sirkuierende strome en die relatiefhoë werwelstoom-verliese in die statorwikkelings.

Made available in DSpace on 2014-10-09T12:37:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:55:58Z (GMT). No. of bitstreams: 1 04760.pdf: 5699610 bytes, checksum: c39af246787ef81d5c48ece3cf888efc (MD5) / Thesis (Ph.D) / IPEN/T / University of Birmingham, Birmingham, England

Made available in DSpace on 2014-10-09T12:37:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:55:58Z (GMT). No. of bitstreams: 1 04760.pdf: 5699610 bytes, checksum: c39af246787ef81d5c48ece3cf888efc (MD5) / Thesis (Ph.D) / IPEN/T / University of Birmingham, Birmingham, England

The rise in popularity of renewable energy solutions, in particular wind energy systems, has resulted in a greater demand for low-speed direct-drive machines. The Vernier machine has inherent properties such as high torque density, sinusoidal induced voltages and low torque ripple which makes it suitable for low-speed direct-drive wind applications. Additionally, its mechanical structure is as simple as a conventional permanent magnet (PM) machine, whilst eliminating the need for a mechanical gearbox. The research problem addressed by this dissertation relates to the assessment of the Vernier permanent magnet (VPM) machine topology for direct-drive wind applications. It aims to outline a sizing, detailed design and analysis approach for a three-phase VPM wind generator. Furthermore, a comparative study is conducted using two different rotor types and two different stator types, namely; spoke-type and surface-mounted and fractional slot and integral slot respectively. Vernier theory is used to size the designs after which 2D Finite Element Analysis (FEA) simulations are used to analyse and validate the designs. The main outcome of the comparative study is an assessment of the suitability of four topologies for the direct-drive wind application. The design is assessed on parameters which are critical for wind turbine functionality; namely efficiency, torque ripple, torque density and material consumption. The most suitable of the topologies is selected for prototyping. The rotor is made more robust by adding structural features which mechanically secure laminations and PMs to the shaft. The FEA analysis of the prototype showed favourable performance characteristics, albeit with a small cost in power density. The prototype was -thus manufactured with further mechanical reinforcements made to the bearing system. Experimental results reveal the presence of a defect in the windings. Parameters which are dependent on the winding design are much lower than the analytical and FEA values. These parameters include resistance, inductance, and back-EMF. Further work should look into determining the root cause of the prototype defects.

A new shipyard on the island of Beckholmen consisting of a new ship hall and complementary workshops. The program is extended with rentable industrial space for other smaller companies to take advantage of synergies with the yard and to create an active maritime cluster around Beckholmen.   By building a marina and a port at the northern shoreline of the island the shipyard can expand their potential customers to non-commercial and larger recreational boats that are becoming increasingly common in Skärgården. The port is also supplemented with a combined naval fuel station, harbor office and a small café. The boat traffic in the region gets a additional stop at the end of the port and act as an additional gateway to Djurgården. Several small retail spaces with direct access to the water is created along the promenade between the port and Djurgården.   The shipyard gets a modern and efficient industry building, while the island is made available to the public again, and Beckholmen will hopefully take an equal place in the city's consciousness as it does visually in the inlet to Stockholm. / Ett nytt varv på Beckholmen bestående av en ny skrovhall samt kompletterande verkstäder. Programmet utökas med uthyrbara industrilokaler för andra mindre marina företag att dra nytta av synergieffekterna hos varvet och för att skapa ett aktivt maritimt kluster runt Beckholmen.   Genom att bygga en marina och gästhamn på norra sidan av ön kan varvet expandera sina potentiella kunder till icke-kommersiella och större fritidsbåtar som blir allt vanligare i Skärgården. Hamnen kompletteras dessutom med en kombinerad sjö bensinstation, hamnkontor och ett litet café. Båttrafiken i regionen får en extra stopp i hamnen och fungerar som en ny kommunikationsled till Djurgården. Flera små kommersiella utrymmen med direkt tillgång till vattnet skapas längs strandpromenaden mellan hamnen och Djurgården.   Varvet får en modern och effektiv industrilokal, medan ön görs tillgängligt för allmänheten igen, och Beckholmen kommer förhoppningsvis att ta en lika stor plats i stadens medvetande som det gör visuellt i inloppet till Stockholm.

Includes abstract. Includes bibliographical references (p. 35-37).

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this laboratory study was to determine if the bond strengths of composite resins and unfilled resins was affected similarly when applied to enamel surfaces which had been previously etched with 50 per cent phosphoric acid. The test specimens were subjected to 24 hours, 30 days, and 6 months storage in water and then subjected to temperature stress cycling and intermittent tensile stress cycling. A tensile test was used to measure the bond strengths of the composite resins (Adaptic and HL-72) and the unfilled resin (Sevriton). The following results were obtained: (1) Pretreating the enamel surface with 50 per cent phosphoric acid for 60 seconds significantly increased the bond strength of composite resins; (2) when placed on acid etched enamel, there was no significant difference in initial bond strengths obtained for the Adaptic and unfilled Sevriton resins; (3) with prolonged water storage, the Adaptic composite resins developed significant loss of bond strength when compared to the unfilled Sevriton resins and the composite HL-72 resins; (4) when Adaptic resins and the HL-72 resin specimens were compared, there was no significant difference in initial bond strengths but the HL-72 specimens were less affected by storage time. Ca45 was used to assess the marginal seal of Adaptic, HL-72, and Sevriton in acid etched and non-etched Class V restorations. One-half of the specimens were thermal cycled 2500 times and stored in water for one week. Control specimens were tested at the end of one week without the thermal cycle. On the basis of these results, it was concluded that acid etching enhances the marginal seal of both composite and unfilled resins. Both composite and unfilled resins experienced increased marginal leakage when the acid etch preparations were thermal cycled, but there were no observable difference in the marginal seal of unfilled resins and composite resins when placed in acid etched restorations.

No description available.