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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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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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A "power-mapping" variable-speed control technique for a constant-frequency conversion system powered by a IC engine and PM generator

A "power-mapping" variable-speed control technique for a con...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： M.J. Ryan R.D. Lorenz GE Corporation Research and Development Power Controls Program Niskayuna NY USA Department of Electrical and Computer Engineering University of Wisconsin Madison Madison WI USA

A variable-speed power conversion system is considered where a permanent magnet generator (PMG) driven by an IC engine supplies power to an electronic inverter. The AC voltage from the PMG is typically diode-rectified into a DC link, which is utilized by the inverter to produce constant-frequency, constant-voltage output. These "electronic gensets" can be smaller, lighter and have higher performance than their fixed-speed counterparts with synchronous alternators under field control. Such attributes are attractive for mobile and stand-by power applications. The added flexibility of a variable-speed genset system must be met with suitable techniques for directing the speed at which the engine should operate for a given electrical load. Constraints on torque, speed, and DC link voltage must additionally be met. This paper reviews conventional methods, and presents a new technique utilizing the operating power of the system as an input to a power-speed "map" for the system to follow. Experimental results are included.

关键词： Electric variables control Engines Inverters Voltage Magnetic variables control Power conversion Permanent magnets Power generation Power supplies Diodes

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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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A Linear Matrix Inequality Approach to The Peak-to-Peak Guaranteed Cost Filtering Design

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IFAC Proceedings Volumes 2000年第14期33卷 29-34页

作者： Reinaldo M. Palhares Pedro L.D. Peres Jaime A. Ramírez Pontifical Catholic University of Minas Gerais Graduate Program in Electrical Engineering Av. Dom José Gaspar 500 Prédio 4 30535-610 Belo Horizonte MG Brazil School of Electrical and Computer Engineering University of Campinas CP 6101 13081-970 Campinas SP Brazil. Department of Electrical Engineering Federal University of Minas Gemis Av. Antônio Carlos 6627 31270-010 Belo Horizonte MG Brazil.

The problem of robust filtering design for uncertain linear systems with guaranteed peak-to-peak performance is addressed in this paper. The uncertain parameters are assumed to belong to convex bounded domains (i.e. polytope type uncertainty). The aim is to design a full-order stable linear filter that minimizes the worst-case peak value of the filtering error output signal with respect to all magnitude bounded noise inputs, in such way that the filtering error system remains robustly stable. The minimization provides an upper bound to the L ∞ induced gain ( ℓ ∞ for discrete-time systems) of the filtering error system. The conditions for the existence of such robust filter are provided in terms of linear matrix inequalities, allowing the use of standard convex optimization procedures to solve the problem. Both continuousand discrete-time systems are considered. The formulation presented is illustrated by examples.

关键词： Robust Estimation Filter Design Uncertain Linear Systems Peak-to-Peak Gain Linear Matrix Inequalities

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Optimizing dual threshold shocks with right- and left-ventricular electrodes: simulating defibrillation with a human thorax model

Optimizing dual threshold shocks with right- and left-ventri...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： N.R. Kramer J.L. Manfra A.L. de Jongh S.J. Hahn B.H. KenKnight F.J. Claydon Joint Program in Biomedical Engineering University of Memphis and University of Tennessee Memphis TN USA Cardiac Rhythm Management Guidant Corporation Saint Paul MN USA Department of Electrical and Computer Engineering University of Houston Houston TX USA

ISBN: (纸本)0780364651

This research focuses on developing new implantable cardioverter defibrillator (ICD) dual lead configurations that reduce the defibrillation threshold (DFT) energy by delivering a second threshold shock in the area where the conventional shock's electric field is weakest. The objective of this study is to optimize electrode placements for lead systems including left-ventricular (LV) electrodes. A physiologically realistic 3D finite element model of the human thorax is employed to compute DFTs. The lead configurations investigated consist of a conventional lead system (TRIAD/sup TM/, Guidant Corporation) and additional LV shocking electrodes placed in the apical and basal portion of the posteriolateral coronary vein or directly within the TRIAD system's weak field region. The LV electrodes measure 50 mm in length and 1 mm in diameter. The computed DFT energy for the TRIAD is 6.2 J, falling within one standard deviation of the mean DFT reported in clinical studies using the TRIAD leads. LV leads located in the apical and basal portion of the posteriolateral coronary vein result in a DFT of 3.1 J, a 50% reduction from the TRIAD alone. LV leads placed in the anterior, middle, and posterior TRLAD weak field result in a DFT of 2.9 J, 2.7 J., and 3.5 J, respectively, corresponding to a 44-56% reduction in DFT from the TRIAD. The results indicate that an additional electrode placed in the proximity of the TRIAD weak field is just as effective in reducing DFTs as one placed directly within the weak field.

关键词： Electric shock Electrodes Defibrillation Humans Thorax Veins Cardiology Finite element methods Torso Biological system modeling

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L-band radiometer measurements of conifer forests

L-band radiometer measurements of conifer forests

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： R.H. Lang P. de Matthaeis D.M. Le Vine S. Bidwell M. Haken N. Chauhan Department of Electrical & Computer Engineering George Washington University Washington D.C. DC USA Microwave Sensor Branch Goddard Space Flight Center NASA Greenbelt MD USA NPO ESS Integrated Program Office (IPO) Silver Spring MD USA

Airborne radiometer measurements were made at L-band over conifer forests in Virginia to study radiometer response to biomass and soil moisture. The horizontally polarized synthetic aperture radiometer, ESTAR, was deployed aboard a NASA-P3B Orion aircraft. Measurements were made in July, August and November of 1999 over relatively homogeneous conifer stands of varying biomass. Concurrently with the aircraft measurements, soil moisture measurements were made in several of the imaged stands. The images of the area show a strong correlation between forest stand biomass and radiometric brightness temperature. In addition, stands growing in soils with poor drainage were identifiable on the image.

关键词： L-band Microwave radiometry Biomass Soil measurements Soil moisture Aircraft Testing Moisture measurement Instruments Polarization

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Robust H ∞ Filtering for Linear Continuous-Time Uncertain Systems With Multiple Delays: An LMI Approach

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IFAC Proceedings Volumes 2000年第14期33卷 249-254页

作者： Reinaldo M. Palhares Pedro L.D. Peres Carlos E. de Souza Pontifical Catholic University of Minas Gerais Graduate Program in Electrical Engineering Av. Dom José Gaspar 500 Prédio 4 30535-610 Belo Horizonte MG Brazil. School of Electrical and Computer Engineering University of Campinas CP 6101 13081-970 Campinas Sp Brazil Department of Systems and Control Laboratório Nacional de Computção Científica - LNCC Av. Getúlio Vargas 333 25651-070 Petrópolis RJ Brazil.

The problem of robust H ∞ filter design for uncertain continuous-time linear systems with multiple time-delayed states is addressed in this paper. The uncertainties are assumed to belong to convex bounded domains (polytope type uncertainty) and the time delays are supposed to be constant. Delay-independent as well as delay-dependent stability conditions assuring robust stability and a prescribed H ∞ disturbance attenuation for the filtering error system are established, in both cases, in terms of linear matrix inequalities, which can be efficiently solved by standard optimization procedures with global convergence assured. Two illustrative examples are analyzed.

关键词： Time-delay systems Delay-dependent stability Delay-independent stability Robust H ∞ filtering Linear matrix inequalities

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1.54 μm Electroluminescence from Erbium-Doped Porous Silicon Composites for Photonic Applications

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physica status solidi (a) 2000年第1期182卷

作者： H.A. Lopez P.M. Fauchet Materials Science Program and Department of Electrical and Computer Engineering University of Rochester Rochester NY 14627 USA

We have fabricated erbium-doped porous silicon (PSi) devices and demonstrated stable room-temperature electroluminescence (EL) at 1.54 μm under both forward and reverse bias conditions. Erbium was infiltrated into the nanostructured matrix of PSi (≤ 10 19 cm —3 ) by cathodic electrochemical migration of the ions followed by high temperature annealing (950–1100 °C). The devices exhibit an exponential EL dependence in both bias conditions as a function of driving current and voltage. External quantum efficiencies of 0.01% have been obtained. The EL intensity in reverse bias and the transport properties of the devices show large temperature dependences. From the differences in temperature, electrical, and EL characteristics in forward and reverse biases, we believe that different excitation mechanisms are responsible for the EL.

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Porous Silicon Encapsulated Nematic Liquid Crystals for Electro-Optic Applications

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physica status solidi (a) 2000年第1期182卷

作者： M.V. Wolkin S. Chan P.M. Fauchet Program in Materials Science and Department of Electrical and Computer Engineering University of Rochester Rochester NY 14627 USA

In this study we present the fabrication, the optical characterization and the electrical operation of a high quality, nanometer-sized, silicon-based light modulator made of nematic liquid crystals (LC) encapsulated into porous silicon (PSi) multilayer matrix. We first demonstrate the infiltration procedure and characterize the cell's reflectance and photoluminescence (PL) before and after infiltration. Then we examine the LC molecular alignment, and show that their long axis is positioned along the pore walls. Therefore, the electrical control of an interference filter is achieved by applying a field horizontal to the pore's directionality. We also demonstrate that by applying up to 10 V the molecules reorient, the effective refractive index is modulated by as much as Δ n = 0.15, and the reflectance spectra is red shifted.

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