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computers in Cardiology (CinC)

作者： J.G. Bosch G. van Burken S.S. Schukking R. Wolff A.J. van de Goor J.H.C. Reiber Laboratory for Clinical and Experimental Image Processing Department of Diagnostic Radiology University Hospital Leiden Netherlands Department of Computer Architecture Faculty of Electrical Engineering Delft University of Technnology Netherlands

A PC-based system for real-time left ventricular endocardial contour detection on echocardiographic images has been developed in our laboratories. The system consists of an IBM-compatible PC equipped with a commercially available frame grabber and the special-purpose Minimum Cost Contour Detector (MCCD) board developed for this project. The MCCD board uses 1 or 2 Intel i960 processors and receives digital images (512*512*8 bit) from the frame grabber over a digital video bar in real time. The contour detection algorithm is based on dynamic programming. Detected contours and other results are transferred to the host via the AT-bus. processing time is short enough for real-time performance in a practical situation. Area of contours and regional areas in 8 segments are calculated in real time and displayed in graphs on the host system. The MCCD board is fully programmable and may be used for similar real-time contour detection applications, e.g. for X-ray angiography and intravascular ultrasound.< >

关键词： Real time systems Laboratories Costs Digital images Detection algorithms Dynamic programming X-ray detection X-ray detectors Angiography Ultrasonic imaging

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Design of limit-cycle-free recursive transfer functions for fixed-point direct form implementation

Design of limit-cycle-free recursive transfer functions for ...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.I. Laakso M. Lang T. Saramaki Nokia Research Center Helsinki Finland Electrical and Computer Engineering Department Rice University TX USA Signal Processing Laboratory Tampere University of Technology Tampere Finland

An approach for the design of limit-cycle-free digital fixed-point filters is proposed. By constraining the transfer function already in the design phase, it is guaranteed that the filter will be free from limit cycles and overflow oscillations in the direct form implementation. The design strategy also guarantees low roundoff noise. The proposed approach is illustrated with design examples. The examples show that typically a 50-100% increase in the filter order (as compared to standard elliptic design) is needed for the limit-cycle-free implementation of a lowpass filter with the direct form (DF) structure. Since the DF structure is very efficient to implement in signal processors, the proposed filters are very attractive for such environment, whereas dedicated filter structures (wave digital, state-space, etc.) easily result in a 3 to 4-fold implementation complexity.< >

关键词： Transfer functions Limit-cycles Electronic mail Digital filters Stability criteria Algorithm design and analysis Design engineering Laboratories Elliptic design Signal processing

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A blind adaptive MAP algorithm for the recovery of cochannel signals

A blind adaptive MAP algorithm for the recovery of cochannel...

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MILCOM, Military Communications Conference

作者： K. Giridhar A. Mathur J.J. Shynk Information Systems Laboratory Department of Elec. Engineering University of Stanford Stanford CA USA Center for Information Processing Research Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

This paper describes a blind adaptive algorithm for the recovery of cochannel data signals in the presence of intersymbol interference. Assuming unknown finite impulse response channel characteristics, the principle of maximum a posteriori symbol detection (MAPSD) is employed to jointly estimate the channels and the transmitted data. In order to reduce the complexity of this joint blind MAPSD algorithm, a cascaded multistage structure is proposed whereby each stage recovers one of the cochannel sources. This suboptimal approach is expected to perform well when the cochannel signals have sufficiently different power levels. computer simulations for a primary signal and a single interferer illustrate the rapid convergence properties of the algorithm.< >

关键词： Maximum likelihood estimation Interchannel interference Intersymbol interference Information systems Laboratories Information processing Data engineering Adaptive algorithm computer simulation Convergence

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Subnanometer alignment system for x‐ray lithography

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1994年第6期12卷 3261-3264页

作者： H. Zhou M. Feldman R. Bass Department of Electrical and Computer Engineering and Center for Advanced Microstructures and Devices (CAMD) Louisiana State University Baton Rouge Louisiana 70803‐5901 Nanoelectronics Processing Facility Naval Research Laboratory Washington DC 20375

Proximity printing with soft x rays is a leading contender for very large scale integrated circuit lithography below 0.25 μm. It will require overlay accuracy far below the 100 nm (3σ) typical of today’s systems. In addition, it should use wafer marks which permit planar resist flow, so their apparent position is not distorted. We report an alignment system which uses a linear zone plate on the mask to focus laser light into a line on the wafer. The wafer mark is the boundary between two adjacent fine pitch gratings. These gratings diffract the light into photodiodes. The gratings either differ slightly in pitch or by 180° in phase. This configuration minimizes the disturbance to the resist as it flows over the alignment mark. In the case of gratings with slightly different pitch the light from each grating is detected by one‐half of a split photodiode. This arrangement has good sensitivity and a very wide capture range. The phase shift gratings have reduced capture range but enhanced sensitivity because of the improved resolution from the phase shift. We observe that the full width at half‐maximum (FWHM) of the alignment signal is 0.6 μm when the FWHM of the zone plate focus is 1.0 μm. By collecting all of the light focused by the zone plate and diffracted by the gratings we obtain strong alignment signals with signal to noise ratios of more than 1000:1. We routinely obtain a reproducibility in a bench setup equivalent to less than 1 nm (3σ). This alignment technique is currently undergoing installation in a commercially available x‐ray exposure tool.

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Fabrication using x‐ray nanolithography and measurement of Coulomb blockade in a variable‐sized quantum dot

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1994年第6期12卷 3611-3613页

作者： M. Burkhardt Henry I. Smith D. A. Antoniadis T. P. Orlando M. R. Melloch K. W. Rhee M. C. Peckerar Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 School of Electrical Engineering Purdue University West Lafayette Indiana 47907 Nanoelectronics Processing Facility U.S. Naval Research Laboratory Washington D.C. 20375

We report on the fabrication and measurement of a novel type of quantum dot device in which the shape and size of the dot can be controlled. The device consists of four uniformly spaced quantum point contacts which can be biased to produce quantum dots ranging in size from 600 nm to below 200 nm. The capacitances of the gates controlling the dot are small. Measurements were made at a temperature of 0.3 K for three different dot sizes. Devices were fabricated in three lithography steps, with x‐ray nanolithography used to define the final gate layer. The device exhibits conductance maxima whose spacing depends on which quantum point contacts are used to define the quantum dot.

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Bayesian techniques for equalization of rapidly fading frequency selective channels

Bayesian techniques for equalization of rapidly fading frequ...

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IEEE Conference on Vehicular Technology (VTC)

作者： Gen-Kwo Lee M.P. Fitz S.B. Gelfand Vides Signal Processing Department Computer & Communication Research Laboratory Industrial Technology and Research Institute Hsinchu Taiwan School of Electrical Engineering Purdue University West Lafayette IN USA

This paper applies the Bayesian conditional decision feedback estimator (BCDFE) to rapidly fading frequency selective channels. The BCDFE is a model-based deconvolution algorithm which jointly estimates the transmitted data and channel parameters. The BCDFE applies joint symbol-by-symbol MAP demodulation and channel estimation to equalize channels, and consequently provides robust performance in rapidly fading channels. We provide a brief derivation of the BCDFE and characterize the performance on the land mobile radio channel. We assess the BCDFE's principle design characteristics and the resulting performance in both transient and steady-state operation. The effects of delay spread, Doppler spread, and co-channel interference on the BEP performance are also presented. The BCDFE demonstrates many of the desirable characteristics of an equalizer for mobile radio.< >

关键词： Bayesian methods Fading Frequency estimation Land mobile radio Feedback Deconvolution Demodulation Channel estimation Robustness Steady-state

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Static program decomposition among machines in an SIMD/SPMD heterogeneous environment with non-constant mode switching costs

Static program decomposition among machines in an SIMD/SPMD ...

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Heterogeneous Computing Workshop

作者： D.W. Watson J.K. Antonio H.J. Siegel M.J. Atallah Department of Computer Science Utah State University Logan UT USA Parallel Processing Laboratory School of electrical Engineering Purdue University West Lafayette IN USA Computer Sciences Department Purdue University West Lafayette IN USA

The problem of minimizing the execution time of programs within a heterogeneous environment is considered. Different computational characteristics within a parallel algorithm may make switching execution from one machine to another beneficial; however, the cost of switching between machines during the execution of a program must be considered. This cost is not constant, but depends on data transfers needed as a result of the move. Therefore, determining a minimum-cost assignment of machines to program segments is not straightforward. A previously presented block-based mode selection (BBMS) approach is used as a basis to develop a heuristic method for assigning machines to program segments of data-parallel algorithms. Simulation results of parallel program behavior using the heuristic indicate that good assignments are possible without resorting to exhaustive search techniques.< >

关键词： Parallel processing Parallel machines Switches Cost function computer science Concurrent computing Parallel algorithms Laboratories Contracts Testing

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On the methodology for comparing learning algorithms: a case

On the methodology for comparing learning algorithms: a case

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Australian and New Zealand Conference on Intelligent Information Systems

作者： A. Bradley B. Lovell M. Ray G. Hawson Department of Electrical and Computer Engineering University of Queensland Brisbane Australia Cooperative Research Centre for Sensor Signal and Information Processing Australia Haemostatis Research Laboratory The Prince Charles Hospital Queensland Health Brisbane Australia

We explore several issues relevant to the benchmarking and comparison of machine learning algorithms. We illustrate those issues with a case study using the decision tree induction algorithms C4.5 (J. Quinlan, 1993) and multiscale classification (MSC) (A.P. Bradley and B.C. Lovell, 1994), multilayer perceptrons (MLP) and multivariable regression (MVR). Then for a "real world" problem we compare estimates of the true error rates for each classifier, first on a single train and test partition, and then using cross validated subsampling techniques. The relevance of the /spl chi//sup 2/ test is then discussed in relation to comparing the classifier accuracies. The paper concludes by evaluating the performance of these four fundamentally different approaches to the solution of this regression problem.< >

关键词： computer aided software engineering Decision trees Classification tree analysis Hospitals Machine learning algorithms Multilayer perceptrons Error analysis Blood Australia Signal processing

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Printability of sub‐150 nm features in x‐ray lithography: Theory and experiments

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1994年第6期12卷 3965-3969页

作者： Scott D. Hector Vincent V. Wong Henry I. Smith M. A. McCord K. W. Rhee Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 IBM Semiconductor Research and Development Center Yorktown Heights New York 10598 Nanoelectronics Processing Facility US Naval Research Laboratory Washington DC 20375

Image formation in x‐ray lithography has been studied extensively. A previous theoretical study predicted that 0.1 μm features can be printed at large gaps (≳10 μm) with absorbers attenuating less than 10 dB. This study seeks to verify rigorous electromagnetic simulations of image formation by directly measuring the aerial image. Exposures of features with linewidths ranging from 0.15 to 0.075 μm were performed on the Helios synchrotron. Pedestal‐style x‐ray masks, consisting of SiNx membranes and a Au absorber, were patterned with e‐beam lithography at 100 and 50 kV. By careful dose control and inspection of the resulting features, one can directly determine the aerial image (the image at the resist surface). This is verified using a string model of the resist development. Aerial image measurements correlate reasonably well with modeling results.

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TECHNICAL ISSUES REGARDING SATELLITE PACKET-SWITCHING

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 257-267页

作者： IVANCIC, WD CHU, P SHYY, DJ National Aeronautics and Space Administration Lewis Research Center Cleveland Ohio 44135 USA. A design engineer in the Digital Technology Branch of the Space Electronics Division. He has extensive experience in satellite communications systems modulation and coding on-board switching and routeing and high speed digital design. Since joining NASA in 1982 Mr. Ivancic has been responsible for the development of a variety of matrix switch controllers ground terminal equipment numerous pieces of special test equipment a beacon controller for the SARSAT program (Search and Rescue Satellite) and a time-shared decoder for a processing satellite. In addition Mr. Ivancic has been technical contract monitor on a number of advanced communications technology contracts including the Advanced Modulation Technology Development a 5 GHz fibre-optic link and multi-programmable modem study. He was awarded the B.S.E.E. and M.S.E.E. degrees by Cleveland State University in 1982 and 1986 respectively. Cleveland State University Cleveland Ohio 44115 USA. Currently an assistant professor of Electrical Engineering Department at Cleveland State University. He obtained the M.S. and Ph.D. degrees from Iowa State University majoring in Electrical and Computer Engineering. His research interests include high-speed computer networks digital systems and neural networks applications. He is a member of Sigma Xi Phi Kappa Phi as well as the IEEE and ACM. ComSearch Reston Virginia 22091 USA. Received the B.S. degree in electrical engineering from National Chiao-Tung University Hsin-Chu Taiwan in 1983 and the M.S. and Ph.D. degrees in electrical engineering from Georgia Institute of Technology Atlanta GA in 1986 and 1990 respectively. From June 1987 to October 1987 he worked for the Department of Neurology Emory University Atlanta as a Programmer. From September 1989 to December 1989 he worked for the Advanced Development Laboratory. AMP Inc. Atlanta as a Test Engineer. From February 1990 to August 1993 he wor

Many concepts for advanced communication satellite networks have recently been proposed. Critical technical issues relating to satellite packet switching for meshed very small aperture terminal networks and broadband ... 详细信息

关键词： FAST PACKET SWITCH BISDN MESHED VSAT ON-BOARD processing

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