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

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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A comparison of training algorithms for DHP adaptive critic neurocontrol

A comparison of training algorithms for DHP adaptive critic ...

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International Joint Conference on Neural Networks (IJCNN)

作者： G.G. Lendaris T.T. Shannon A. Rustan Systems Science Ph.D. Program and Electrical & Computer Engineering Department Portland State University USA

A variety of alternate training strategies for implementing the dual heuristic programming (DHP) method of approximate dynamic programming in the neurocontrol context are explored. The DHP method of controller training has been successfully demonstrated by a number of authors on a variety of control problems in recent years, but no unified view of the implementation details of the method has yet emerged. A number of options are described for sequencing the training of the controller and critic networks in DHP implementations. Results are given about their relative efficiency and the quality of the resulting controllers for two benchmark control problems.

关键词： Neural networks Shape control Dynamic programming Equations Design optimization Amorphous materials Design methodology Feedback loop Supervised learning Process design

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A HIGH-RESOLUTION TIME-FREQUENCY ANALYSIS OF THE SINGING VOICE

A HIGH-RESOLUTION TIME-FREQUENCY ANALYSIS OF THE SINGING VOI...

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1999 International Workshop on Models and Analysis of Vocal Emissions for Biomedical Applications, MAVEBA 1999

作者： Mellody, Maureen Wakefield, Gregory H. Applied Physics Program 500 East University Dr. Ann ArborMI48109-1120 United States Department of Electrical Engineering and Computer Science University of Michigan 1301 Beat Ave. Ann ArborMI48109-2122 United States

We apply the modal distribution, a high-resolution time-frequency distribution, to the study of sung musical passages. Evidence is presented comparing the modal distribution with the spectrogram for a set of synthetic signals which emulate human singing. We then compare the two techniques for sung passages from four student sopranos with respect to measures of the instantaneous frequency and amplitude of the partials. In general, the modal distribution appears to be a more sensitive measure of individual differences in vocal production than the spectrogram. © 1999 Models and Analysis of Vocal Emissions for Biomedical Applications, MAVEBA 1999. All rights reserved.

关键词： Modal analysis

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Integrated real time multi-channel wavelength monitoring circuit using phased-array waveguide grating

Integrated real time multi-channel wavelength monitoring cir...

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Optical Fiber Communication (OFC) Conference

作者： Shan Zhong Chau-Han Lee Xiao Lin Xiao-Hui Yang Yung-Jui Chen D. Stone Department of Computer Science and Electrical Engineering And Joint Program for Advanced Electronic Materials University of Maryland Baltimore County Baltimore MD USA

An integrated multichannel wavelength monitoring circuit using specially designed phased-array waveguide grating and detector arrays, which monitors all wavelength-division multiplexing channels in real-time (sixteen ... 详细信息

ISBN: (纸本)155752582X

关键词： Circuits Gratings Wavelength division multiplexing Throughput computerized monitoring Phased arrays Wavelength measurement Detectors Sensor arrays computer science

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Proximal femoral density patterns are consistent with bicentric joint loads

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computer Methods in Biomechanics and Biomedical engineering 1999年第4期2卷 271-283页

作者： Fischer, Kenneth J. Jacobs, Christopher R. Levenston, Marc E. Cody, Dianna D. Carters, Dennis R. Musculoskeletal Research Center Department of Orthopaedic Surgery University of Pittsburgh Pittsburgh PA 15213 United States Department of Orthopaedics Musculoskeletal Research Laboratory Pennsylvania State University School of Medicine Hershey PA 17033 United States Department of Electrical Engineering and Computer Science Continuum Elect romechanics Mhoratory Massachusetts Institute of Technology Hershey MA 02139 United States Department of Diagnostic Radiology Division of Radiologic Physics and Engineering Henry Ford Hospital Detroit MI 48202 United States Department of Veterans Affairs Medical Center Rehabilitation Research and Development Center Palo Alto CA 94304-1200 United States Department of Mechanical Engineering Stanford University Biomechanical Engineering Program Stanford CA 94305-402 United States

We developed an alternate method for density-based load estimation and applied it to estimate hip joint load distributions for two femora. Two-dimensional finite element models were constructed from single energy quantitative computed tomography (QCT) data. Load estimation was performed using five loading regions on the femoral head. Within each loading region, individual nodal loads, normal to the local surface, were supplied as input to the load estimation. An optimization procedure independently adjusted individual nodal load magnitudes in each region, and the magnitudes of muscle forces on the greater trochanter, such that the applied tissue stimulus approached the reference stimulus throughout the model. Dominant estimated load resultant directions were generally consistent with published experimental data for loads during gait. The estimated loads also suggested that loads near the extremes of the articulating surface may be important (even required) for development and maintenance of normal bone architecture. Estimated load distributions within nearly all regions predicted bicentric loading patterns, which are consistent with observations of hip joint incongruity. Remodeling simulations with the estimated loads predicted density distributions with features qualitatively similar to the QCT data sets. This study illustrates how applications of density-based bone load estimation can improve understanding of dominant loading patterns in other bones and joints. The prediction of bicentric loading suggests a very fine level of local adaptation to details of joint loading. © 1999 OPA (Overseas Publishers Association) N.V.

关键词： Finite element method

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Comparative study of back surface field contact formation using different lamp configurations in rapid thermal processing

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Journal of Vacuum science & Technology B: Microelectronics Processing and Phenomena 1998年第2期16卷 613-613页

作者： Singh, R. Vedagarbha, V. Nimmagadda, S.V. Narayanan, S. Department of Electrical and Computer Engineering and Materials Science and Engineering Program Clemson University Clemson South Carolina 29631-0915 Department of Electrical and Computer Engineering Clemson University Clemson South Carolina 29631-0915 Solarex Corporation 630 Solarex Court Frederick Maryland 21701

In this article, we have studied the role of photoeffects in the formation of aluminum back surface field (BSF) contacts on p-type silicon wafers by using different lamp configurations in rapid thermal processing (RTP). Use of photons of wavelengths less than 800 nm in conjunction with infrared and visible photons in RTP resulted in the reduction of processing time from 202 to 138 s and the processing temperature from 890 to 850 °C. The reduction in the overall thermal budget used for BSF contact formation is a direct result of photon assisted RTP. The availability of a large number of high energy photons on the metal surface also resulted in improved electrical, structural and mechanical properties of the processed device.

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Multiwavelength integrated 2 × 2 optical cross-connect switch and lambda-partitioner with 2 × N phased-array waveguide grating in self-loopback configuration

Multiwavelength integrated 2 × 2 optical cross-connect swit...

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1998 Optical Fiber Communication Conference, OFC 1998

作者： Li, Haifeng Lee, Chau-Han Zhong, Shan Chen, Yung Jui Dagenais, M. Stone, D. Department of Computer Science and Electrical Engineering University of Maryland Baltimore County Joint Program for Advanced Electronic Materials 1000 Hilltop Circle BaltimoreMD21250 United States

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Royal Academy of Medicine in Ireland - Section of bioengineering - Proceedings of meeting held in Dundalk, Co. Louth, in February 1998.

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IRISH JOURNAL OF MEDICAL science 1998年第4期167卷 256-276页

作者： [Anonymous] Orthopaedic Research Unit The Queen’s University of Belfast School of Biomedical Sciences The Queen’s University of Belfast Howmedica International Ltd. Raheen Industrial Estate Limerick Department of Mechanical Engineering Trinity College Dublin 2 Mater Hospital Dublin 7 Orthopaedic Research Laboratory Århus University Hospital Denmark University of Limerick Limerick Limerick Regional Hospital Raheen Limerick Boston Scientific Ireland Ltd. Galway Department of Mechanical Engineering University College Dublin Dublin Department of Electrical and Electronic Engineering University College Dublin Dublin Bioengineering Research Centre Department of Mechanical Engineering University College Dublin Dublin Northern Ireland Bio-Engineering Centre (NIBEC) School of Electrical and Mechanical Engineering University of Ulster Newtownabbey Department of Mechanical & Manufacturing Engineering The Ashby Building The Queen’s University of Belfast Johnson and Johnson Professional Orthopaedic Division Queensway England Department of Cardiology and Department of Medical Physics & Bioengineering St. James’s Hospital Dublin 8 Burke House Ellison Street Castlebar Royal College of Surgeons in Ireland Department of Surgery Beaumont Hospital Dublin Department of Electronic and Electrical Engineering Trinity College Dublin 2 Department of Aeronautical Engineering The Queen’s University of Belfast Vascular Unit Belfast City Hospital Department of Medical Physics and Bioengineering St. James’s Hospital Dublin 8 Centre for Biomedical Electronics Department of Electronic and Computer Engineering University of Limerick Limerick Department of Mechanical and Aeronautical Engineering University of Limerick Limerick School of Health Sciences University of Ulster Ireland School of Physiotherapy University of Ulster Newtownabbey Clinical Engineering NI Medical Physics Agency Belfast and Radiology Royal Victoria Hospital Musgrave Park Hospital University of Limerick Biomedical Institute (ULBMI) Uni

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Improved lightpath (wavelength) routing in large WDM networks

Improved lightpath (wavelength) routing in large WDM network...

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International Conference on Distributed Computing Systems

作者： Weifa Liang G. Havas Xiaojun Shen Department of Mathematics University of Queensland QLD Australia Centre for Discrete Mathematics and Computing Department of Computer Science and Electrical Engineering University of Queensland QLD Australia Computer Science Telecommunications Program University of Missouri Kansas City Kansas City USA

We address the problem of efficient circuit switching in wide area networks. The solution provided is based on finding optimal routes for lightpaths and semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining several lightpaths together, using wavelength conversion at their junctions. The problem thus is to find an optimal lightpath/semilightpath in the network in terms of the cost of wavelength conversion and the cost of using the wavelengths on links. We first present fast, efficient algorithms both for the general problem and for a natural restricted version. The new algorithms outperform earlier work, providing time improvements amounting to an almost linear time factor in most cases. Also, all our algorithms can be implemented on the network in a distributed way.

关键词： Wavelength routing Intelligent networks WDM networks Optical wavelength conversion Biomedical optical imaging Optical fiber networks Costs High speed optical techniques Bandwidth Mathematics

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