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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： F. Tejada A.G. Andreou J.A. Miragliotta R. Osiander D. Wesolek Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD USA Applied Physics Laboratory Laurel MD USA

The performance of microelectromechanical sensor systems relies critically on the transduction method employed to convert the mechanical displacement into an electrical signal. Optical readout techniques have distinct advantages over more traditional capacitive and piezoelectricity transduction methods. They are employed in applications where atomic resolution with a small sensing area is necessary, for example, scanning probe microscopes. In this paper, we present two architectures for optoelectronic sensing based on silicon on sapphire CMOS (SOS-CMOS) technology. We show how to heterogeneously integrate photodetectors, analog CMOS signal processing circuits, and VCSELs for an array based optical readout system. The optical transparency of the sapphire substrate allows for the design of both Michelson and Fabry-Perot type interferometers that are amenable to 2D array sensing. We present preliminary experimental data demonstrating standing wave detection in the 100 nm thin silicon PIN photodiodes available in the SOS-CMOS technology for the Fabry-Perot interferometer.

关键词： Silicon Optical interferometry Optical signal processing Optical arrays Optical sensors Atom optics CMOS technology Sensor systems Piezoelectricity Signal resolution

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Surface micromachining in Silicon on Sapphire CMOS technology

Surface micromachining in Silicon on Sapphire CMOS technolog...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： F. Tejada A.G. Andreou D.K. Wickenden A.S. Francomacaro Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD USA Applied Physics Laboratory Laurel MD USA

We report on the design and fabrication of surface micromachined microelectromechanical structures (MEMS) in an ultra thin silicon (UTSi) on sapphire CMOS process [Peregrine Semiconductor (PE) Silicon on Sapphire (SOS) process]. This is the first demonstration of surface micromachined MEMS structures in a CMOS process fabricated on a sapphire substrate.

关键词： CMOS technology Micromachining Silicon Micromechanical devices Fabrication physics Laboratories CMOS process Semiconductor device measurement Capacitors

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Eulerian method for computing multivalued solutions of the Euler-Poisson equations and applications to wave breaking in klystrons

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Physical Review E 2004年第1期70卷 016502-016502页

作者： Xiantao Li John G. Wöhlbier Shi Jin John H. Booske The Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Department of Electrical and Computer Engineering University of Wisconsin Madison Wisconsin 53706 USA Department of Mathematics University of Wisconsin Madison Wisconsin 53706 USA

We provide methods of computing multivalued solutions to the Euler-Poisson system and test them in the context of a klystron amplifier. An Eulerian formulation capable of computing multivalued solutions is derived from a kinetic description of the Euler-Poisson system and a moment closure. The system of the moment equations may be closed due to the special structure of the solution in phase space. The Eulerian moment equations are computed for a velocity modulated electron beam, which has been shown by prior Lagrangian theories to break in a finite time and form multivalued solutions. The results of the Eulerian moment equations are compared to direct computation of the kinetic equations and a Lagrangian method also developed in the paper. We use the Lagrangian formulation for the explicit computation of wave breaking time and location for typical velocity modulation boundary conditions.

关键词： Klystrons

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Survey of atmospheric remote sensing techniques leveraging information in passive IR spectral radiance measurements

Survey of atmospheric remote sensing techniques leveraging i...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： A.K. Lazarevich M.E. Thomas C.R. Philbrick R.I. Joseph Applied Physics Laboratory Johns Hopkins University Laurel MD USA Department of Electrical Engineering Pennsylvania State University PA USA Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD USA

Several techniques exist for using ground-based measurements of IR radiance to characterize the atmosphere, especially the boundary layer. These methodologies, in contrast to space based observations or active probing techniques, offer a safe, continuous measure of atmospheric parameters at a single location that are highly accurate at altitudes very near the ground (<500 m) and can be obtained without the need for human monitoring. Herein we demonstrate the use of data from a BOMEM MR 140 spectroradiometer for estimation of temperature and water vapor profiles. Temperature profiles are calculated using a simple process based on temperature invariant spectral points of downwelling mid-wave IR (MWIR) radiance; the basic algorithm was reported in 2000. Results reported here include an update to the fit algorithm as well as qualitative comparisons to field test data obtained in 1999 where an active Raman LIDAR and a balloonsonde measured the vertical temperature profile and vertical water vapor profile during an MR data collection. Once the vertical temperature profile is known, the vertical water vapor profile can be calculated using the same radiometric data. Water vapor profiles are calculated in much the same way as temperature profiles, using a simple inversion process, except different altitude points are based on temperature dependent absorption lines instead of temperature invariant points

关键词： Remote sensing Atmospheric measurements Land surface temperature Temperature dependence Temperature measurement Atmosphere Extraterrestrial measurements Humans Condition monitoring Spectroradiometers

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Spike sorting with support vector machines

Spike sorting with support vector machines

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

作者： R.J. Vogelstein K. Murari P.H. Thakur C. Diehl S. Chakrabartty G. Cauwenberghs Johns Hopkins University Baltimore MD US Applied Physics Laboratories Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD USA

Spike sorting of neural data from single electrode recordings is a hard problem in machine learning that relies on significant input by human experts. We approach the task of learning to detect and classify spike waveforms in additive noise using two stages of large margin kernel classification and probability regression. Controlled numerical experiments using spike and noise data extracted from neural recordings indicate significant improvements in detection and classification accuracy over linear amplitude- and template-based spike sorting techniques.

关键词： Sorting Support vector machines Support vector machine classification Electrodes Machine learning Humans Additive noise Kernel Noise level Data mining

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JUNCTION-TEMPERATURE MEASUREMENTS INGaNUV LIGHT-EMITTING DIODES USING THE DIODE FORWARD VOLTAGE

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International Journal of High Speed Electronics and Systems 2004年第3期14卷 708-713页

作者： Y. XI E. F. SCHUBERT Future Chips Constellation Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy New York 12180 USA Future Chips Constellation Department of Physics Applied Physics and Astronomy Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy New York 12180 USA Future Chips Constellation Rensselaer Polytechnic Institute Troy New York 12180 USA.

A theoretical model for the dependence of the diode forward voltage (V f ) on junction temperature (T) is developed. A new expression for d V f / d T is derived that takes into account all relevant contributions to the temperature dependence of the forward voltage including the intrinsic carrier concentration, the bandgap energy, and the effective density of states. Experimental results on the junction temperature of GaN UV LEDs are presented. Excellent agreement between the theoretical and experimental temperature coefficient of the forward voltage ( d V f / d T) is found. The experimentally found linear dependence of the junction temperature on forward current is explained by a thermal conduction model. A thermal resistivity of 342.2 K/W is found for the UV LED.

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IEEE Photonics Conference (IPC)

作者： F.O. Ilday F.W. Wise F.X. Kaertner Department of Electrical Engineering and Computer Sciences and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA USA School Of Applied Physics and Engineering Cornell University Ithaca NY USA

We investigate the possibility of self-similar pulse evolution in solid state lasers. Numerical simulations with realistic parameters for a Ti:sapphire laser indicate that pulse energies of up to 1 nJ should be possible.

关键词： Optical pulses Laser theory Laser mode locking Solid lasers Fiber lasers Optical pulse generation Laser modes Pulse shaping methods Numerical simulation Laser stability

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Tutorial on multisensor management and fusion algorithms for target tracking

Tutorial on multisensor management and fusion algorithms for...

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American Control Conference (ACC)

作者： M.K. Kalandros L. Trailovic L.Y. Pao Y. Bar-Shalom Air Defense Systems Department Johns Hopkins University-Applied Physics Laboratory Laurel MD USA Department of Electrical and Computer Engineering University of Colorado Boulder CO USA Department of Electrical and Systems Engineering University of Connecticut Storrs CT USA

This paper provides an introduction to sensor fusion techniques for target tracking. It presents an overview of common filtering techniques that are effective for moving targets as well as methods of overcoming problems specific to target tracking, such as measurement-to-track association and sensor registration. The computational demand of such algorithms is discussed and various practices, including distributed processing of target tracks and sensor management, are proposed to help reduce this demand. Final comments include a discussion of applications and implementation issues specific to the presented scenarios.

关键词： Tutorial Target tracking Radar tracking Sensor fusion State estimation Acoustic measurements Electromagnetic measurements Radar measurements Measurement uncertainty Filtering

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Relation between quantum tunneling times for relativistic particles

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Physical Review A 2004年第5期70卷 052112-052112页

作者： Herbert G. Winful Moussa Ngom Natalia M. Litchinitser Department of Electrical Engineering University of Michigan Ann Arbor MI 48109-2122 1301 Beal Avenue United States Applied Physics Program University of Michigan 2477 Randall Laboratory Ann Arbor MI 48109-1120 United States

A general relation between the phase time (group delay) and the dwell time is derived for relativistic tunneling particles described by the Dirac equation. It is shown that the phase time equals the dwell time plus a ... 详细信息

关键词： Quantum theory

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Microwave remote sensing of land

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URSI Radio Science Bulletin 2004年第308期2004卷 30-48页

作者： P. Pampaloni K. Sarabandi Institute of Applied Physics (IFAc) of National Research Council (CNR) via Panciatichi 64 50127 Florence Italy Department of Electrical Engineering & Computer Science Radiation Laboratory 1301 Beal Ave. University of Michigan

Considering the rapid growth of population, its impact on the environment, and limited available resources on our planet, the need for monitoring the environmental processes and managing our resources is unequivocal. Microwave remote sensing provides a unique capability towards achieving this goal. Over the past decade, significant progress has been made in microwave remote sensing of land processes through development of advanced airborne and space-borne microwave sensors, and the tools — such as physics-based models and advanced inversion algorithms — needed for analyzing the data. These activities have sharply increased in recent years since the launch of the ERS-1/2, JERS-1, and RADARS AT satellites, and with the availability of radiometric data from SSM/I. A new era has begun with the recent space missions ESA-ENVISAT, NASA-AQUA, and NASDA-ADEOSII, and the upcoming PALSAR and RADARSAT2 missions, which open new horizons for a wide range of operational microwave remote-sensing applications. This paper highlights major activities and important results achieved in this area over the past years.

关键词： Synthetic aperture radar Spaceborne radar Sensors Microwave imaging Microwave radiometry Remote sensing Microwave theory and techniques

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