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The main goal of this thesis project is to identify interesting concepts related to cooling of electrical motors and generators which could be evaluated using suitable computer simulation tools. As the project proceeded it was decided to focus on investigating how the air from a fan flows along the finned frame of a general purpose low voltage electrical machine, how the heat is transferred between the frame and the cooling air and what the temperature distribution looks like. It was also investigated if it is possible to make improvements in the effectiveness of the cooling without adding additional coolers. This investigation focused on varying the fin design and evaluating the resulting temperature distribution. Due to the complex nature of the simulations a segment, and not the full frame, was considered. Simulation model validation was performed through comparing air speed measurements that were performed on two different machines with the corresponding simulated air speed. The validation showed that good agreement between simulated and measured air speeds are obtained. The conclusion from the simulations is that slight modifications to the current fin design could increase the cooling effect of the finned surface. The air velocity measurements also indicate that the cooling of the machines surface could potentially be improved by small changes in the exterior of the frame. / Målet med detta examensarbete var att identifiera intressanta koncept relaterade till kylning av elektriska maskiner och generatorer, som kunde utvärderas med lämplig programvara för datorsimuleringar. Under projektets gång så bestämdes det att fokusera på hur luften från en fläkt flödar längs med en generell lågspänningsmaskin, hur värmen överförs från ramen till den omgivande luften och hur temperaturfördelningen ser ut. Det undersöktes även om det var möjligt att förbättra effektiviteten av kylningen utan att ansluta extra kylanordningar. Undersökningarna fokuserades på olika fendesigner och dess påverkan på värmefördelningen. På grund av simuleringarnas komplexitet så har simuleringarna endast utförts på ett segment istället för hela maskinen. Validering av simuleringarna utfördes genom att jämföra de simulerade lufthastigheterna med verklig lufthastighet som mättes på två maskiner i testmiljö. Valideringen visade att simuleringarna överensstämmer väl med de mätningar som utfördes. Slutsatsen utifrån simuleringarna är att mindre förändringar av fenornas nuvarande design kan förbättra fenornas kylningsförmåga. Mätningarna av lufthastigheten ger även indikationer på att kylningen av maskinens utsida eventuellt kan förbättras genom små förändringar av ramens exteriör.

Recent years have witnessed a proliferation of flash memories as an emerging storage technology with wide applications in many important areas. Like magnetic recording and optimal recording, flash memories have their own distinct properties and usage environment, which introduce very interesting new challenges for data storage. They include accurate programming without overshooting, error correction, reliable writing data to flash memories under low-voltages and file recovery for flash memories. Solutions to these problems can significantly improve the longevity and performance of the storage systems based on flash memories. In this work, we explore several new data representation techniques for efficient and reliable data storage in flash memories. First, we present a new data representation scheme—rank modulation with multiplicity —to eliminate the overshooting and charge leakage problems for flash memories. Next, we study the Half-Wits — stochastic behavior of writing data to embedded flash memories at voltages lower than recommended by a microcontroller’s specifications—and propose three software- only algorithms that enable reliable storage at low voltages without modifying hard- ware, which can reduce energy consumption by 30%. Then, we address the file erasures recovery problem in flash memories. Instead of only using traditional error- correcting codes, we design a new content-assisted decoder (CAD) to recover text files. The new CAD can be combined with the existing error-correcting codes and the experiment results show CAD outperforms the traditional error-correcting codes.

The continuing trend of miniaturization in semiconductor devices has enabled the integration of complex functionalities on-chip, leading to a proliferation of wireless devices for both mobile and in-office applications. The use of scaled CMOS technologies for high-frequency wireless devices is posing daunting technological challenges, both in the design and post-manufacture testing of such devices. The issue of device power consumption and heat dissipation is also dominating future wireless transceiver designs. This is driven by the trend of increasing operating speeds coupled with dense integration of multi-mode functionalities onto compact form-factors on-chip. In this thesis, a framework for reliable low-power operation of wireless devices is presented. The presented approaches significantly reduce device test costs during production, and operate the device at very low power consumption levels during field operation of the device. Low-cost test, diagnosis, and tuning techniques to reduce to reduce test cost of devices and operational reliability in field. To reduce device power consumption during field operation, adaptation is performed continuously while ensuring that system-level performance metrics are never violated. This approach has direct implications for boosting the battery life of portable wireless devices while ensuring their operational reliability.

Thesis (M.S.)--State University of New York at Binghamton, Department of Computer Science, Thomas J. Watson School of Engineering and Applied Science, 2006. / Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: M. Jamal Deen. Includes bibliographical references (leaves 154-164). Also available online.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: M. Jamal Deen. Includes bibliographical references (leaves 154-164). Also available online.

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 73-75).

Thesis (Ph. D.)--Carleton University, 2004. / Includes bibliographical references (p. 137-150). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 75-77). Also available in electronic format on the Internet.