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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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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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GA-based kernel optimization for pattern recognition: theory for EHW application

GA-based kernel optimization for pattern recognition: theory...

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Congress on Evolutionary Computation

作者： M. Yasunaga T. Nakamura I. Yoshihara J.H. Kim Institute Information Science and Electrical University of Tsukuba Tsukuba Ibaraki Japan Doctoral Program of Engineering University of Tsukuba Tsukuba Ibaraki Japan Miyazaki University Miyazaki Japan The Center for Advanced Computer Studies University of Louisiana Lafayette LA USA

An extension of the kernel-based pattern recognition method using a genetic algorithm is proposed. The method is suited to evolvable pattern recognition hardware using FPGAs. In the conventional method one common kernel function is used in the superposition to make discrimination functions. In the extended method each region of the kernel function is optimized individually. For the kernel-region optimization we use a genetic algorithm to solve a large combinatorial problem almost impossible to solve using any brute-force search. A chromosome represents the kernel region in an n-dimensional pattern space, and each locus corresponds to one of the candidates (genes) for an edge length of the kernel region. We have applied the extended method to a sonar spectrum recognition problem and obtained a recognition accuracy of 83.9%, which is much higher than the 62.0% obtained using the conventional kernel-based method and is also better than 82.7% obtained using the nearest neighbor method and the 83.0% obtained using a neural network (backpropagation algorithm). We have analyzed the individually optimized kernel regions and shown that the GA process automatically extracts features in the patterns and embeds the features in the kernel regions.

关键词： Kernel Pattern recognition Genetic algorithms Hardware Field programmable gate arrays Optimization methods Biological cells Sonar applications Nearest neighbor searches Neural networks

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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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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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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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Laser-mediated cartilage reshaping with feedback-controlled cryogen spray cooling: Biophysical properties and viability

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Lasers in Surgery and Medicine 2000年第1期28卷

作者： A.M. Karamzadeh BS, BA A. Rasouli BS B.S. Tanenbaum BS T.E. Milner PhD J.S. Nelson MD, PhD B.J.F. Wong MD Beckman Laser Institute and Medical Clinic University of California Irvine Irvine California 92697 Department of Engineering Harvey Mudd College Claremont California 91711 Biomedical Engineering Program Department of Electrical and Computer Engineering University of Texas at Austin Austin Texas 78712-1084 Department of Otolaryngology-Head and Neck Surgery University of California Irvine Orange California 92869

Background and Objective Recent studies have indicated that chondrocyte viability decreases with prolonged or repeated laser irradiation. To optimize laser-mediated cartilage reshaping, the heating process must be finely controlled. In this study, we use high-power Nd:YAG laser irradiation (λ = 1.32 μm) combined with cryogen spray cooling (CSC) in an attempt to reshape porcine septal cartilage while enhancing chondrocyte viability. Study Design/Materials and Methods Chondrocyte viability was determined after high-power (50 W/cm 2 ) Nd:YAG-mediated cartilage reshaping with and without cryogen spray cooling (CSC) and correlated with dynamic measurements of tissue optical and thermal properties. Results After 1.5 to 2.0 seconds of laser exposure, characteristic changes in diffuse reflectance (indicating the onset of accelerated stress relaxation) was observed in both laser only and laser with CSC specimens. After 2 seconds of laser exposure, specimens in both groups retained the curved shape for up to 14 days. After one laser exposure, chondrocyte viability was 94.35 ± 6.1% with CSC and 68.77 ± 20.1% ( P < 0.05) without CSC. After two laser exposures, a similar trend was observed with CSC (70.18 ± 16.44%) opposed to without CSC (28 ± 45%; P < 0.05). Conclusion CSC during high-power laser irradiation allows rapid heating while minimizing extreme front surface temperature elevations and axial thermal gradients. Laser irradiation with CSC can be used to effectively reshape cartilage tissue with the additional advantage of increasing chondrocyte viability. Lasers Surg. Med. 28:1–10, 2001. © 2001 Wiley-Liss, Inc.

关键词： hemocytometry otolaryngology plastic surgery reconstruction

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Effects of source traffic shaping on MPEG video transmission over next generation IP networks 8

Effects of source traffic shaping on MPEG video transmission...

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8th International Conference on computer Communications and Networks, ICCCN 1999

作者： Alam, Mohammad F. Atiquzzaman, Mohammed Karim, Mohammad A. Electro-Optics Program University of Dayton DaytonOH45469-0245 United States Department of Electrical and Computer Engineering University of Dayton DaytonOH45469-0226 United States Department of Electrical and Computer Engineering University of Tennessee KnoxvilleTN37996-2100 United States

ISBN: (纸本)0780357949

The Internet engineering Task Force (IETF) has defined the integrated services model for supporting real-time services. Guaranteed service is one of these services with firm delay and bandwidth guarantees. Before setting up a guaranteed service flow, traffic parameters of the source have to be specified in terms of token bucket traffic descriptors. The source must conform to these descriptors by shaping its traffic. In this paper, we study the effects of a token bucket traffic shaper at the source on the transmission characteristics of Motion Picture Experts Group (MPEG) video streams over the guaranteed service. For different types of MPEG video sequences, the effects of the shaper parameters on the transmission performance are studied. We develop an analytical model of the traffic shaper, and also carry out numerical simulation of the transmission performance to verify the analytical model. Our study also provides a technique to analyze stored MPEG video sequences to determine the token bucket traffic descriptors that have to be specified during flow set up. © 1999 IEEE.

关键词： Analytical models

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Finite-difference time-domain simulation of light scattering from multiple cells

Finite-difference time-domain simulation of light scattering...

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Quantum Electronics and Laser Science Conference, QELS 1999

作者： Myakov, A.V. Sergeev, A.M. Dolin, L.S. Myakov, A.V. Richards-Kortum, R. Institute of Applied Physics Russian Academy of Sciences 46 Uljanov st Nizhny Novgorod603600 Russia Biomedical Engineering program Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78731 United States

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