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26th International computer Music Conference, ICMC 2000

作者： Mellody, Maureen Wakefield, Gregory H. Applied Physics Program University of Michigan United States Department of Electrical Engineering and Computer Science University of Michigan United States

Signals from 12 soprano and mezzo-soprano singers are analyzed with the modal distribution, a high-resolution time-frequency analysis method, to obtain measures of instantaneous amplitude and frequency of the signals’ partial components. These estimates are used to construct singer-specific transfer functions for each vowel and pitch analyzed. An AR approximation to a residual representation of these transfer functions is determined. This low-order residual approximation is used in a hierarchical clustering experiment. Using this representation, functions from each singer for a given vowel tend to cluster into a single class before classes collapse across singers. This result suggests that the low-order residual approximation captures singer-specific features in the sung signals. © 2000 ICMC. All Rights Reserved.

关键词： Transfer functions

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Polarization effects and transport in AlGaN/GaN system

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2000年第4期18卷 2322-2327页

作者： Yifei Zhang Yulia Smorchkova C. Elsass Stacia Keller James Ibbetson Steven DenBaars Umesh Mishra Jasprit Singh Applied Physics Program University of Michigan Ann Arbor Michigan 48109 Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor Michigan 48109-2122 Department of Electrical and Computer Engineering University of California Santa Barbara California 93106 Department of Electrical Engineering and Computer Engineering University of Michigan Ann Arbor Michigan 48109

The AlGaN/GaN heterostructure is important for both electronic and optoelectronic devices. In addition to having a large band gap, the heterostructure has a strong piezoelectric effect and a large spontaneous polarization. This allows one to incorporate a large electric field (>106 V/cm) and high sheet charge (>1013 cm−2) without doping. Theoretical studies are done to examine how polarization effects controls the sheet charge density. The studies also focus on how interface roughness, aluminum mole fraction in the barrier, impurity scattering, sheet charge density, and phonon scattering influence mobility. Results are compared with experimental studies on samples grown by both molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). We find that interface roughness is a dominant source of scattering in the samples reported. Due to the variation in growth techniques we find that the MBE samples have a smoother interface quality compared to the MOCVD samples. By carefully fitting the experimental data we present results on interface roughness parameters for MBE and MOCVD samples.

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Quantum Confinement in Nanocrystalline Si Superlattices

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MRS Online Proceedings Library 2000年第1期592卷 359-364页

作者： G. F. Grom P. M. Fauchet L. Tsybeskov J. P. McCaffrey H. J. Labbé D. J. Lockwood Department of Mechanical Engineering Materials Science Program USA Department of Electrical and Computer Engineering University of Rochester Rochester USA Institute for Microstructural Sciences National Research Council Ottawa Canada

Photoconductance spectroscopy was used to probe the effects of quantum confinement in nanocrystalline (nc)-Si/amorphous (a)-SiO2 superlattices (SLs). A Metal-Oxide-Semiconductor (MOS)-like structure with the nc-Si SL incorporated in the oxide was fabricated to study charging/discharging processes in Si nanocrystals. The fine structure observed in photoconductance spectra at low temperatures was interpreted in terms of singularities in the carrier density of states, possibly due to energy quantization. In addition, a low-resistance sample exhibited photocurrent oscillations with a frequency of several kHz, which could be a manifestation of sequential resonant carrier tunneling in the nc-Si/a-SiO2 SL.

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Investigation of NMR signal-to-noise ratio for RF scroll microcoils

Investigation of NMR signal-to-noise ratio for RF scroll mic...

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International Conference on Microtechnologies in Medicine and Biology

作者： B. Gimi S. Grant G. Friedman R. Magin Department of Bioengineering University of Illinois Chicago Chicago IL USA Department of Electrical Engineering and Computer Science University of Illinois Chicago Chicago IL USA

Although NMR has the ability to investigate biological systems non-destructively, it suffers from low sensitivity compared to other analytical techniques. Therefore, optimizing radio frequency (RF) coils to improve sensitivity is an area of significant focus in NMR Sensitivity can be improved for mass- and volume-limited samples by reducing, coil diameter, and adding sensing layers to the coil. This paper demonstrates that around skin depth, coil sensitivity can be increased with additional sensing layers, by using multilayered scroll coil geometries. While solenoids have demonstrated increased sensitivity over conventional coils (Helmholtz, Saddle, and Birdcage), their dimensions are limited by wire diameter, and difficulty in fabrication at reduced dimensions. The novel scroll geometry avails of microfabrication techniques to provide flexibility in manufacturing coils at very reduced dimensions.

关键词： Nuclear magnetic resonance Signal to noise ratio Radio frequency Coils Geometry Biological systems Skin Solenoids Wire Fabrication

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A room temperature unipolar quantum dot intersubband long wavelength (13.3 /spl mu/m) laser

A room temperature unipolar quantum dot intersubband long wa...

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IEEE Photonics Conference (IPC)

作者： S. Krishna P. Bhattacharya J. Singh J. Urayama T.B. Norris P.J. McCann K. Namjou Applied Physics Program Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA School of Electrical and Computer Engineering University of Oklahama Norman OK USA

Summary form only given. We report the room temperature operation of a novel unipolar self-organized quantum dot FIR laser (13.3 /spl mu/m) based on transitions between discrete bound electron states in self-organized... 详细信息

关键词： Quantum dot lasers US department of Transportation Electrons Infrared detectors Stationary state Finite impulse response filter Land surface temperature Infrared spectra Spectroscopy Laser radar

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Classification and estimation of ultrasound speckle noise with neural networks

Classification and estimation of ultrasound speckle noise wi...

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IEEE Symposium on Bioinformatics and bioengineering (BIBE)

作者： M.P. Wachowiak A.S. Elmaghraby R. Smolikova J.M. Zurada Electrical and Computer Eng. Department University of Louisville Louisville KY USA Computer Science and Engineering Program University of Louisville Louisville KY USA Computer Eng. and Computer Science Department University of Louisville Louisville KY USA

Presents a neural-based approach to classifying and estimating the statistical parameters of speckle noise found in biomedical ultrasound images. Speckle noise, a very complex phenomenon, has been modeled in a variety of different ways: and there is currently no clear consensus as to its precise statistical characteristics. In this study, different neural network architectures are used to classify ultrasound images contaminated with three types of noise, based upon three one-parameter statistical distributions. At the same time: the parameter is estimated. It is expected that accurate characterization of ultrasound speckle noise will benefit existing post-processing methods, and may lead to new refinements in these techniques.

关键词： Ultrasonic imaging Speckle Neural networks Additive noise computer science Parameter estimation computer networks Statistical distributions Adaptive filters Biomedical computing

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Spreadsheet model for MorphoSys RC array

Spreadsheet model for MorphoSys RC array

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IEEE International Conference on Electronics, Circuits and Systems (ICECS)

作者： H. Diab E. Abdennour N. Mansour Department of Electrical and Computer Eng'g Faculty of Engineering and Architecture American University of Beirut Beirut Lebanon Computer Science Program Lebanese American University Beirut Lebanon

ISBN: (纸本)0780365429

This paper introduces reconfigurable computing and MorphoSys, which is a reconfigurable system. It also explains the architecture of its reconfigurable hardware part. Then, it presents two spreadsheet models for the operation of this reconfigurable device. The first spreadsheet performs the modelling through formulas, while the second does it numerically. These spreadsheet models serve as design and debugging tools.

关键词： Registers Hardware computer architecture Application software Reduced instruction set computing Multiplexing Numerical models Debugging Application specific integrated circuits Parallel processing

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On the Perception of Transients: Applying Psychophysical Constraints to Improve Audio Analysis and Synthesis 26

On the Perception of Transients: Applying Psychophysical Con...

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26th International computer Music Conference, ICMC 2000

作者： Wakefield, Gregory H. Heller, Laurie M. Carney, Laurel H. Mellody, Maureen Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Naval Submarine Medical Research Laboratory GrotonCT06359 United States Hearing Research Center Dept. of Biomedical Engineering Boston University BostonMA02215 United States Applied Physics Program University of Michigan United States

In a psychophysical experiment, a wideband, 4-ms noise is compared with spectrally smoothed versions of the noise. To isolate on the magnitude spectrum, the phase spectrum is controlled by assigning the same random phase spectrum to both the original and smoothed signals. Depending on the choice of phase spectrum, discrimination thresholds for spectral shape vary from a maximum spectral deviation of 2-3 dB to as much as 25 dB. The exact source of this effect remains an open question. However, it suggests that not all transients require the same signal fidelity. Given a proper characterization of the perceptual response, it may be possible to reduce the size of the codebook required to maintain acceptable perceptual results. © 2000 ICMC. All Rights Reserved.

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Biophysical and spectral characteristics of cool- and warm-season grasslands under three land management practices in Eastern Kansas

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Natural Resources Research 2000年第4期9卷 321-331页

作者： Guo, Xulin Price, Kevin P. Stiles, James M. Kansas Applied Remote Sensing Program (KARS) Department of Geography University of Kansas Lawrence KS 66045 2335 Irving Hill Road United States Radar Systems and Remote Sensing Laboratory (RSL) Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS 66045 2335 Irving Hill Road United States Lawrence KS 66045 2335 Irving Hill Road United States

Grasslands are the largest of the Earth's four major vegetation types and are among the most agriculturally productive lands. Grassland management practices alter biophysical factors, such as plant species composition, soil structure and chemistry, and primary productivity. Large-scale changes in land management practices can have significant impacts on available natural resources, therefore impacting a regional socioeconomics. For these reasons, an improved understanding of the geographic distribution of changing land management practices and how these changes affect grassland biophysical characteristics of an area is critical to improve land use planning and practices. This study investigated the spectral characteristics, as measured using satellite remotely sensed data, of three land management practices [grazing, haying, and management under Conservation Reserve program (CRP)] on areas dominated by cool- and warm-season grasslands. The satellite imagery was acquired in May, July, and September in 1997 over Douglas County, Kansas. Biomass, vegetation cover, and species richness data were collected around the satellite overflight periods. Our results indicate that the biophysical characteristics and spectral reflectances are significantly different among the three management practices over cool- and warm-season grasslands. Interestingly, sites grazed by livestock had the highest species richness and the highest forb cover, although the total cover is almost the same as the other practices, and they have the highest near-infrared reflectance throughout the growing season. © 2000 International Association for Mathematical Geology.

关键词： Landsat Tallgrass prairie Thematic Mapper (TM)

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Fast cerebral functional signals in the 100 ms range detected by frequency-domain near-infrared spectroscopy

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NeuroImage 2000年第5 PART II期11卷 S515页

作者： Wolf, Martin Wolf, Ursula Toronov, Vlad Paunescu, L. Adelina Michalos, Antonios Franceschini, Maria Angela Fantini, Sergio Gratton, Enrico Laboratory for Fluorescence Dynamics Department of Physics University of Illinois at Urbana-Champaign Urbana IL 61801-3080 1110 W. Green St. United States Bioengineering Center Department of Electrical Engineering and Computer Science Medford MA 02155 4 Colby Street United States

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