Experimental study on turbulence characteristics of a slot jet impingement on semi-circular surfaces

2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A diagrammatic approach to search for minimum sampling frequency and quantization resolution for digital control of power converters

A diagrammatic approach to find out the minimum sampling frequency and quantization resolution for digital control of power converters is proposed. The proposed solution algorithm combines consideration on both time sampling and quantization resolution axes to search for the minimum required digital controller settings. Experiments results are presented to justify the proposed algorithm. © 2007 IEEE.published_or_final_versio

Least coupling paths model for non-contact EMI base on lump element approach in switch mode converter

A simplified physical model concludes a minimum of six equivalent physical coupling paths, Least Coupling Paths (LCP), using lump elements approach through non-contact EMI coupling mechanism to the terminals of LISN. Simulation shows both inductive and capacitive coupling through each path may produce substantial EMI measured by a LISN. This physical model is good for understanding, diagnosis and emission estimation.published_or_final_versio

A novel high frequency current-driven synchronous rectifier applicable to most switching topologies

A novel current-driven synchronous rectifier is presented in this paper. With the help of current sensing energy recovery circuit, the proposed current-driven synchronous rectifier can operate at high switching frequency with high efficiency. Compared with those voltage-driven synchronous rectification solutions, this current-driven synchronous rectifier has several outstanding characteristics. It can be easily applied to most switching topologies like an ideal diode. Constant gate drive voltage can be obtained regardless of line and load fluctuation. This makes it desirable in high input range application. Converters designed with this synchronous rectifier are also capable of being connected in parallel without taking the risk of reverse power sinking. Principle of operation is given in the paper. A series of experiments verify the analysis and demonstrate the merits.published_or_final_versio

Analysis of the resonance modes of PZT/epoxy 1-3 composite rings

Author name used is this publication: C. P. ChongRefereed conference paper2001-2002 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Current-driven synchronous rectification technique for flyback topology

For low voltage, high current application, synchronous rectification technique can help improve efficiency in a flyback converter. This paper investigates some technical challenges within a synchronous rectification flyback converter. One of the major problems is that the discontinuous current mode (DCM) operation is not achievable with a control-driven or self-driven synchronous rectifier. Continuous current mode operation may introduce excessive RMS current and circulation energy at light load or high line condition. To solve this problem, we propose to use an energy recovery current-driven synchronous rectifier for flyback topology. Analysis and experiments demonstrate the performance of this approach.published_or_final_versio

Fast tracking of evoked potential variations using correlated scale function designed by multiresolution analysis

Fast tracking of evoked potential variations is of great importance in clinical operation. The paper describes a method whereby an ensemble averaged signal is used as the prototype of the scale function and designs a correlated scale function based on multiresolution analysis. Hence, an effective low pass digital filter having powerful tracking capability is obtained. Results show that the filter designed filters out the noise more effectively than that using general wavelet filtering, and the tracking of the peak of evoked potential is easily obtained.published_or_final_versio

Analysis of buck-boost converter inductor loss using a simpleonline B-H curve tracer

A simple method to plot online B-H curves and calculate the core loss of the inductor in a conventional buck-boost power converter is developed. In order to obtain a reliable loss data, measurement error and phase shift error are analyzed and then quantified. A new method to minimize measurement error is given. A new core loss model in terms of switching duty cycle is presented. This model predicts variation of core loss of an inductor operating in various conditions in a switching converter. This inductor model can be generalized to inductors in other switching converter topologies.published_or_final_versio

Subpixel Temperature Measurements in Plasma Jet Environments Using High-Speed Multispectral Pyrometry

A high-speed (2 kHz) near-infrared (1.0-1.65 mu m) multispectral pyrometer was used for noninvasive measurements of the subpixel temperature distribution near the sharp leading edge of a wing exposed to a supersonic plasma jet. The multispectral pyrometer operating in the field measurement mode was able to measure the spatial temperature distribution. Multiple spectra were used to determine the temperature distributions in the measurement region. The spatial resolution of the multispectral pyrometer was not restricted to one &quot;pixel&quot; but was extended to subpixel accuracy (the temperature distribution inside one pixel in the image space corresponding to the point region in the object space). Thus, this system gives high-speed, multichannel, and long working time spatial temperature measurements with a small data stream from high-speed multispectral pyrometers. The temperature distribution of the leading edge of a ceramic wing was investigated with the leading edge exposed to extreme convective heating from a high-enthalpy plasma flow. Simultaneous measurements with a multispectral pyrometer and an imaging pyrometer verify the measurement accuracy of the subpixel temperature distribution. Thus, this multispectral pyrometry can provide in situ noninvasive temperature diagnostics in supersonic plasma jet environments.</p

CS 3180/5180: Comparative Languages

This course will introduce fundamental concepts and paradigms underlying the design of modern programming languages. For concreteness, we study the details of an object-oriented language (e.g. Java, C#, C++), a functional language (e.g., Scheme, and get introduced to multiparadigm languages (e.g., Python, Scala). The overall goal is to enable comparison and evaluation of existing languages. The programming assignments will largely be coded in Java and in Scheme, and optionally in Python or Scala