http://hdl.handle.net/1957/7302 Search the Channel search http://ir.library.oregonstate.edu/jspui/simple-search http://hdl.handle.net/1957/13071 Title: Design techniques for high efficiency LED drivers<br/><br/>Authors: Bang, Sarvesh Jagdish<br/><br/>Abstract: The increasing popularity of cellular phones with integrated cameras in therecent past has led to major improvements in its image quality. However, integration of new features, such as mobile email, video streaming, MP3 etc. tend to put the limitation on image quality as camera phone designers struggle to manage multiple features while maintaining healthy battery life time.In this research, a novel efficient power management scheme for cameraphones with flash for better image/video quality is discussed. A prototype power management circuit comprising of a 2 MHz Buck-and-Boost DC-DC converter driving up to 1.2A flash light emitting diode (LED) in 500nm CMOS process is implemented. The converter achieves high efficiency over the entire Li-On battery voltage range of 3.0V to 5.2V by operating in buck, buck-and-boost and boost mode based on the input/output voltage and load current requirements. The proposed pulse width modulator (PWM) controller operates continuously over the entire Li-On battery range while providing constant LED current. The converter shows peak efficiencies of 87% and 83% for LED current of 0.6A and 1.2A, respectively.<br/><br/>Description: Graduation date: 2010 http://hdl.handle.net/1957/12770 Title: A Strategy-Centric Approach to the Design of End-User Debugging Tools<br/><br/>Authors: Grigoreanu, Valentina; Burnett, Margaret; Robertson, George<br/><br/>Abstract: End-user programmers’ code is notoriously buggy. This problem is amplified by the increasing complexity of end users’ programs. To help end users catch errors early and reliably, we employ a novel approach for the design of end-user debugging tools: a focus on supporting end users’ effective debugging strategies. This paper has two core contributions. We first demonstrate the potential of a strategy-centric approach to tool design by presenting StratCel, a strategy-based tool for Excel. Second, we show the benefits of this design approach: participants using StratCel found twice as many bugs as participants using standard Excel, they fixed four times as many bugs, and all this in only a small fraction of the time. Furthermore, this strategy-based approach helped the participants who needed it the most: boosting novices’ debugging performance near experienced participants’ improved levels. Finally, we reveal several opportunities for future research about strategy-based debugging tools. http://hdl.handle.net/1957/12844 Title: Directional 60 GHz communication networks<br/><br/>Authors: Yildirim, Ferhat<br/><br/>Abstract: It is well known that multipath effects cause inter-symbol interference (ISI) for high-speed signaling and ultimately limit the achievable data rate at any frequency band. In this thesis, we study several different methods to tackle this issue and provide solutions for establishing efficient wireless links that can provide several Gbps data rate. Specifically, we show that proper choice of polarization, when used with the proposed topology detection algorithm reduces the multipath in 60 GHz wireless channel and increases the error-performance of the network. We also develop a direction-detection algorithm for directional communications in 60 GHz, which is proven to be effective in reducing multipath and increasing spatial diversity. Finally, we propose a double directional channel model for 60 GHz channel as a modification to IEEE 802.15.3c channel model to include the effects of directional antennas both on the transmitter and the receiver side.<br/><br/>Description: Graduation date: 2010 http://hdl.handle.net/1957/12706 Title: End-User Debugging of Machine-Learned Programs: Toward Principles for Baring the Logic<br/><br/>Authors: Kulesza, Todd; Stumpf, Simone; Riche, Yann; Burnett, Margaret; Wong, Weng-Keen; Oberst, Ian; Moor, Travis; McIntosh, Kevin; Bice, Forrest<br/><br/>Abstract: Many applications include machine learning algorithms intended to learn “programs” (rules of behavior) from an end user’s actions. When these learned programs are wrong, their users receive little explanation as to why, and even less freedom of expression to help the machine learn from its mistakes. In this paper, we develop and explore a set of candidate principles for providing salient debugging information to end users who would like to correct these programs. We informed the candidate principles through a formative study, built a prototype that instantiates them, and conducted a user study of the prototype to collect empirical evidence to inform future variants. Our results suggest the value of exposing the machine’s reasoning process, supporting a flexible debugging vocabulary, and illustrating the effects of user changes to the learned program’s logic.