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IEEE Conference on Decision and Control

作者： Peter B. Jones Sanjoy K. mitter MIT Lincoln Laboratories Lexington MA USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA

ISBN: (纸本)1424401704

Modern environments are saturated with sensors. These sensors may be active or passive, stationary or mobile, based on land, sea, air or space. They may differ in size, complexity, modes of operation, power, costs and a number of other features. The challenge in a sensor-rich environment is to coordinate the sensing of all the sensors in order to obtain the best total group performance. The complexity of the problem suggests that traditional methods of optimization will be prohibitively costly in terms of computation and communication. Additionally, there is some ambiguity over how to aggregate individual sensor utilities into a "best total group performance." Under these circumstances, game theoretic methods can be employed to both limit the computation and communication necessary for group coordination and avoid the problem of aggregating utilities. Specifically, an economic paradigm is adopted from which an efficient method for sensor coordination can be derived. The resultant coordination algorithm is shown to have bounded Pareto suboptimality, demonstrating the tradeoff between inter-sensor communication and utility optimization

关键词： Iterative algorithms Power generation economics Magnetic sensors Game theory USA Councils Space stations Costs Optimization methods Aggregates Environmental economics

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A balanced optical-RF phase detector

A balanced optical-RF phase detector

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Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser science Conference, CLEO/QELS 2006

作者： Kim, J. Ludwig, F. Cheever, D. Ilday, F.Ö. Burnham, J. Kärtner, F.X. Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 United States Notkestrasse 85 22607 Hamburg Germany MIT-Bates Linear Accelerator Center 21 Manning Ave Middleton MA 01949 United States

A balanced optical-RF phase detector for the extraction of low-jitter RF-signals from optical pulse trains, which is robust against drifts and photodetector nonlinearities, is presented. Sub-10 fs in-loop relative tim... 详细信息

ISBN: (纸本)1557528136

关键词： Phase comparators

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Functional imaging of rat somatosensory cortex using optical coherence tomography (OCT)

Functional imaging of rat somatosensory cortex using optical...

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Biomedical Topical Meeting, BIO 2006

作者： Chen, Y. Aguirre, A.D. Ruvinskaya, L. Devor, A. Boas, D.A. Fujimoto, J.G. Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Harvard-MIT Division of Health Sciences and Technology United States Martinos Center for Biomedical Imaging Department of Radiology Massachusetts General Hospital Harvard Medical School United States

Simultaneous OCT and video microscopy were performed on rat somatosensory cortex during forepaw stimulation. Fractional changes in localized regions of OCT images reveal a functional signal time-course similar to hemo... 详细信息

ISBN: (纸本)1557528071

关键词： Optical tomography

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Quantitative Analysis of QRS Detection Algorithms Based on the First Derivative of the ECG

Quantitative Analysis of QRS Detection Algorithms Based on t...

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

作者： Natalia M. Arzeno Chi-Sang Poon Zhi-De Deng Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA NIH USA Harvard MIT Division of Health Sciences and Technology Massachusetts Institute of Technology Cambridge MA USA Department of Electrical Engineering and Computer Science and the Department of Physics Massachusetts Institute of Technology Cambridge MA USA

Accurate processing of electrocardiogram (ECG) signals requires a sensitive and robust QRS detection method. In this study, three methods are quantitatively compared using a similar algorithm structure but applying different transforms to the differentiated ECG. The three transforms used are the Hilbert transformer, the squaring function, and a second discrete derivative stage. The first two have been widely used in ECG and heart rate variability analysis while the second derivative method aims to explain the success of the Hilbert transform. The algorithms were compared in terms of the number of false positive and false negative detections produced for records of the mit/BIH Arrhythmia Database. The Hilbert transformer and the squaring function both produced a sensitivity and positive predictivity of over 99%, though the squaring function had a lower overall detection error rate. The second derivative resulted in the highest overall detection error rate. Different algorithms performed better for diverse ECG characteristics; suggesting that an algorithm can be specified for different recordings, the algorithms can be combined based on each one's characteristics to determine a new more accurate method, or an additional detection stage can be added to reduce the number of false negatives

关键词： Algorithm design and analysis Detection algorithms Electrocardiography Heart rate variability Discrete transforms Databases Signal processing Band pass filters Error analysis Cities and towns

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A balanced optical-RF phase detector

A balanced optical-RF phase detector

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Conference on Lasers and Electro-Optics (CLEO)

作者： J. Kim F. Ludwig D. Cheever F. O. Ilday J. Burnham F. X. Kartner Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts USA Deutsches Elektronen-Synchrotron (DESY) Hamburg Germany MIT-Bates Linear Accelerator Center Middleton MA USA Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts

关键词： Optical pulses Fiber optics Optical fibers Optical fiber sensors Optical sensors Optical detectors Adaptive optics

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Dynamic-goal state equations for tracking reaching movements using neural signals

Dynamic-goal state equations for tracking reaching movements...

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IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)

作者： L. Srinivasan E.N. Brown Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology USA Department of Anesthesia and Critical Care Massachusetts General Hospital USA Department of Brain and Cognitive Sciences MIT USA

Motor prosthetic algorithms were recently proposed to combine target and path information to drive reaching arm movements to a static goal. In this paper, we extend two approaches to support goals that may themselves evolve over the duration of the reaching movement. The resulting probabilistic and control-based dynamic-goal reach state equations represent an intermediate level of user flexibility between static-goal reach state equations and unconstrained movement

关键词： Equations Tracking State estimation Prosthetics Stochastic processes Trajectory Random variables Uncertainty Anesthesia Hospitals

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Xenon Difluoride Dry Etching of Si, SiGe Alloy and Ge

Xenon Difluoride Dry Etching of Si, SiGe Alloy and Ge

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International SiGe Technology and Device Meeting, ISTDM

作者： Guangchi Xuan T.N. Adam J. Suehle E. Fitzgerald P. Lv N. Sustersic M.J. Coppinger J. Kolodzey Electrical and Computer Engineering Department University of Delaware Newark DE USA IBM Corporation Yorktown NY USA University of Delaware Newark DE US Materials Science and Engineering Department MIT Cambridge MA USA

Xenon diflouride (XeF 2 ) vapor has been known to be able to spontaneously etch Si isotropically at high rates up to 10 mum/min. This dry etching process does not require plasmas or catalysts, and thus causes little damage to the electronic properties. It is useful for releasing free standing structures by etching away Si sacrificial layers or for gate oxide failure analysis by etching away the backside Si. In this work, the etching of Si, SiGe alloys and Ge was studied and results were discussed. Both SiGe and Ge were found to be etched by XeF 2 vapor, and at faster rates than Si

关键词： Xenon Dry etching Silicon germanium Germanium silicon alloys Germanium alloys Silicon alloys Plasma properties NIST Materials science and technology Plasma applications

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Native point defects in yttria and relevance to its use as a high-dielectric-constant gate oxide material: First-principles study

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Physical Review B 2006年第10期73卷 104101-104101页

作者： J. X. Zheng G. Ceder T. Maxisch W. K. Chim W. K. Choi Singapore-MIT Alliance 4 Engineering Drive 3 Singapore 117576 Department of Materials Science and Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139-66307 USA Department of Electrical & Computer Engineering National University of Singapore 4 Engineering Drive 3 Singapore 117576

Yttria (Y2O3) has become a promising gate oxide material to replace silicon dioxide in metal-oxide-semiconductor devices. Using a first-principles approach the electronic structure, defect structure, and formation energy of native point defects in Y2O3 are studied. Vacancies, interstitials, and antisites in their relevant charge states are considered. We find that within the band gap of Y2O3 oxygen vacancies, oxygen interstitials, yttrium vacancies, and yttrium interstitials can be stable depending on the Fermi level and external chemical potentials. When the Fermi level is constrained to be within the band gap of silicon, oxygen vacancies are the dominant defect type under low oxygen chemical potential condition. A higher oxygen chemical potential leads to oxygen interstitials and ultimately yttrium vacancies.

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Electromagnetically induced transparency in superconducting quantum circuits: Effects of decoherence, tunneling, and multilevel crosstalk

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Physical Review B 2006年第10期73卷 104516-104516页

作者： Zachary Dutton K. V. R. M. Murali William D. Oliver T. P. Orlando Naval Research Laboratory Washington DC 20375 USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02138 USA MIT Lincoln Laboratory 44 Wood Street Lexington Massachusetts 02420 USA

We explore theoretically electromagnetically induced transparency (EIT) in a superconducting quantum circuit (SQC). The system is a persistent-current flux qubit biased in a Λ configuration. Previously [Phys. Rev. Lett. 93, 087003 (2004)], we showed that an ideally prepared EIT system provides a sensitive means to probe decoherence. Here, we extend this work by exploring the effects of imperfect dark-state preparation and specific decoherence mechanisms (population loss via tunneling, pure dephasing, and incoherent population exchange). We find an initial, rapid population loss from the Λ system for an imperfectly prepared dark state. This is followed by a slower population loss due to both the detuning of the microwave fields from the EIT resonance and the existing decoherence mechanisms. We find analytic expressions for the slow loss rate, with coefficients that depend on the particular decoherence mechanisms, thereby providing a means to probe, identify, and quantify various sources of decoherence with EIT. We go beyond the rotating wave approximation to consider how strong microwave fields can induce additional off-resonant transitions in the SQC, and we show how these effects can be mitigated by compensation of the resulting ac Stark shifts.

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Long-distance optical synchronization system for X-ray free electron lasers

Long-distance optical synchronization system for X-ray free ...

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Conference on Lasers and Electro-Optics (CLEO)

作者： F. O. Ilday A. Winter H. Schlarb J. Chen A. Benedict J. W. Kim D. Cheevers D. Wong F. X. Kartner Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA Deutsches Electronen Synchrotron DESY Hamburg Germany MIT-Bates Linear Accelerator Center Middleton MA USA

Next generation light sources demand femtosecond-level synchronization of its subcomponents over distances of several km. We demonstrate an optical synchronization system based on distribution of mode-locked pulses ov... 详细信息

关键词： Optical fibers Ultrafast optics Fiber lasers Fiber optics Laser stability Optical pulses Synchronization

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