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International Workshop on Advanced Motion Control (AMC)

作者： O. Bebek K. Erbatur Department of Electrical Engineering and Computer Science Case Western Reserve University USA Mechatronics Program Faculty of Engineering and Natural Sciences Sabanci University Turkey

Recent years witnessed a growing interest in biped walking robots because of their advantageous use in the human environment. However, their control requires many problems to be solved because of the many degrees of freedom and nonlinearity in their dynamics. The so-called open loop walking with offline trajectory generation is one of the control approaches in the literature. There are various difficulties involved in this approach, the most important one being the difficulty in tuning the gait parameters. This paper proposes an online fuzzy adaptation scheme for one of the trajectory parameters in the offline generated walking pattern. A fuzzy identifier system, represented as a three-layer feed-forward neural network is employed to compute the parameter as a function of time in simulations. Fuzzy system parameters are adapted via back-propagation. Virtual torsional springs are attached to the trunk center of the biped. The torque generated by the springs serve as the criterion for the tuning and they help maintaining a stable and a longer walk which is necessary for the online tuning process. 3D simulation and animation techniques are employed for a 12-DOF biped robot to test the proposed adaptive method.

关键词： Legged locomotion Open loop systems Fuzzy systems Springs Humans Fuzzy neural networks Feedforward systems Neural networks Feedforward neural networks computer networks

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New class of the FPGA efficient cryptographic primitives

New class of the FPGA efficient cryptographic primitives

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： N.A. Moldovyan M.A. Eremeev N. Sklavos O. Koufopavlou Specialized Center of Program Systems SPECTR Saint Petersburg Russia Electrical & Computer Engineering Department University of Patras Patras Greece

This work focuses the problem of further development of the approach to the fast cipher design, based on data-dependent (DD) permutations (DDP). A new class of the DDP-like operations is described. New DD operations (DDO) are constructed replacing the switching element in the DDP boxes by different controlled elements (CE) having the same size. Full classification of CE with two non-linear outputs is presented. Two subclasses of nonlinear CE, with the best differential characteristics are recommended for the use in the non-linear DDO-boxes synthesis. The non-linear CE boxes are implemented in FPGA modules using the same hardware resources as switching elements. It is shown that the use of the nonlinear DDO, instead of DDP allows one to reduce the number of rounds. With this technique higher Performance/Cost ratio is achieved, while designing fast hardware suitable ciphers.

关键词： Field programmable gate arrays Cryptography Hardware Data security Size control Data engineering Design engineering Costs Design optimization Boolean functions

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Minimum size primitives for efficient VLSI implementation of DDO-based ciphers

Minimum size primitives for efficient VLSI implementation of...

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Mediterranean Electrotechnical Conference (MELECON)

作者： A.A. Moldovyan N.A. Moldovyan N. Sklavos Specialized Center of Program Systems SPECTR Saint Petersburg Russia Electrical & Computer Engineering Department University of Patras Patras Greece

This work focuses the problem of increasing the performance of the ciphers based on data-dependent (DD) operations (DDO) for VLSI implementations. New minimum size primitives are proposed to design DDOs. Using advanced DDOs instead of DD permutations (DDP) in the DDP-based iterative ciphers Cobra-H64 and Cobra H128 the number of rounds has been significantly reduced yielding enhancement of the "performance per cost" value. To obtain further enhancement of this parameter a new crypto-scheme based on the advanced DDOs is proposed. The FPGA implementation of the proposed crypto-scheme achieves higher throughput value and minimizes the allocated resources than the conventional designs.

关键词： Very large scale integration Cryptography Field programmable gate arrays Communication system security Information security Hardware Data security Data engineering Throughput Resource management

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A summating, exponentially-decaying CMOS synapse for spiking neural systems

A summating, exponentially-decaying CMOS synapse for spiking...

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17th Annual Conference on Neural Information Processing Systems, NIPS 2003

作者： Shi, Rock Z. Horiuchi, Timothy Electrical and Computer Engineering Department University of Maryland College Park MD 20742 United States Institute for Systems Research University of Maryland College Park MD 20742 United States Neuroscience and Cognitive Science Program University of Maryland College Park MD 20742 United States

ISBN: (纸本)0262201526

Synapses are a critical element of biologically-realistic, spike-based neural computation, serving the role of communication, computation, and modification. Many different circuit implementations of synapse function exist with different computational goals in mind. In this paper we describe a new CMOS synapse design that separately controls quiescent leak current, synaptic gain, and time-constant of decay. This circuit implements part of a commonly-used kinetic model of synaptic conductance. We show a theoretical analysis and experimental data for prototypes fabricated in a commercially-available 1.5μm CMOS process.

关键词： CMOS integrated circuits

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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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Exploration of Breast Tumors Utilizing Noninvasive Near-Field Microwave Imaging

Exploration of Breast Tumors Utilizing Noninvasive Near-Fiel...

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Conference on Precision Electromagnetic Measurements (CPEM)

作者： Wael Saleh David Wright Philip Slade Nasser Qaddoumi Microwave hnaging & Nondestructive Evaluation Laboratory minel Electrical Engineering Program School of Engineering American University of Sharjah Sharjah UAE Electronic Systems Research Group Department of Engineering School of Engineering and Computer Science University of Exeter Exeter UK

A novel microwave nondestructive testing technique is presented for breast cancer detection. A method utilizing the reflection coefficient at the aperture of a waveguide sensor radiating into a breast is described resulting in theoretical microwave images that clearly indicate the presence of a tumor. These images demonstrate the feasibility of detecting breast tumors using this approach

关键词： Breast tumors Microwave imaging Microwave theory and techniques Nondestructive testing Breast cancer Cancer detection Reflection Apertures Waveguide theory Image sensors

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Picosecond response of metal-semiconductor-metal ultraviolet phootodiodes

Picosecond response of metal-semiconductor-metal ultraviolet...

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Conference on Lasers and Electro-Optics, CLEO

作者： Li, Jianliang Donaldson, W.R. Hsiang, T.Y. University of Rochester Material Science Program Laboratory for Laser Energetics 250 East River Road Rochester NY 14623 United States Laboratory for Laser Energetics University of Rochester 250 East River Road Rochester NY 14623-1299 United States Department of Electrical and Computer Engineering University of Rochester Rochester NY 14627 United States

We studied the ultrafast response in metal-semiconductor-metal ultraviolet photodiodes fabricated on GaN. The best performance of a device with 1-μmn finger width and spacing showed a 3.5-ps response. The pulse width... 详细信息

关键词： Photodiodes

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Vehicle detection and tracking using acoustic and video sensors

Vehicle detection and tracking using acoustic and video sens...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： R. Chellappa Gang Qian Qinfen Zheng Center for Automation Research Institute for Advanced Computer Studies University of Maryland College Park MD USA Department of Electrical Engineering and Arts Media and Engineering Program Arizona State University Tempe AZ USA

Multimodal sensing has attracted much attention in solving a wide range of problems, including target detection, tracking, classification, activity understanding, speech recognition, etc. In surveillance applications, different types of sensors, such as video and acoustic sensors, provide distinct observations of ongoing activities. We present a fusion framework using both video and acoustic sensors for vehicle detection and tracking. In the detection phase, a rough estimate of target direction-of-arrival (DOA) is first obtained using acoustic data through beam-forming techniques. This initial DOA estimate designates the approximate target location in video. Given the initial target position, the DOA is refined by moving target detection using the video data. Markov chain Monte Carlo techniques are then used for joint audio-visual tracking. A novel fusion approach has been proposed for tracking, based on different characteristics of audio and visual trackers. Experimental results using both synthetic and real data are presented. Improved tracking performance has been observed by fusing the empirical posterior probability density functions obtained using both types of sensors.

关键词： Vehicle detection Acoustic sensors Target tracking Direction of arrival estimation Object detection Multimodal sensors Speech recognition Surveillance Acoustic signal detection Phase detection

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Joint semiblind channel estimation and data detection for MIMO-OFDM systems

Joint semiblind channel estimation and data detection for MI...

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Proceedings of the IEEE Circuits and Systems Symposium on Emerging Technologies

作者： Jiang Yue Kyeong Jin Kim T. Reid J.D. Gibson Department of Electrical Engineering Southern Methodist University Dallas TX USA Nokia Research Center TX Nokia Research Center Irving TX USA Media Arts and Technology Program and Electrical & Computer Engineering University of California Santa Barbara Santa Barbara CA

In MIMO systems, where multiple antennas are used at both transmitter and receiver to achieve high spectral efficiency, channel impulse responses are often assumed to be constant over a block or packet. This assumption of block stationarity on channels is valid for most fixed wireless scenarios. However, for communications in a high mobility environment, the assumption will result in considerable performance degradation. In this paper, we focus on channel estimation for a MIMO system with OFDM transmission technique. In our system, pilots are placed on N/sub P/ subcarriers for a novel channel estimation at the receiver with Kalman filters. With the channels estimated by a Kalman filter, we apply the QRD-M algorithm for suboptimal data detection with reasonable computational cost. The outputs of data detection are fed back to another Kalman filter for an improved channel estimation. By alternatively and iteratively using these two Kalman filters, a better channel estimation can be obtained. A simulation result of the bit error rate shows the improvement of 10 dB in SNR with four iterations over noniteration.

关键词： Channel estimation MIMO Receiving antennas Transmitting antennas Transmitters Degradation OFDM Iterative algorithms Computational efficiency Computational modeling

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A nanoscale approach to stamp fabrication in hard materials using high intensity ultrafast lasers

A nanoscale approach to stamp fabrication in hard materials ...

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2003 MRS Fall Meeting

作者： McDonald, Joel P. Picard, Yoosuf N. Yalisove, Steven M. Liu, Hsiao-Hua Blaszczak, Joseph Guo, Lingji J. Dept. of Materials Science and Engineering University of Michigan Ann Arbor MI 48109-2176 United States Center for Ultrafast Optical Science University of Michigan Ann Arbor MI 48109-2099 United States Applied Physics Program University of Michigan Ann Arbor MI 48109-1120 United States Dept. of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122

Nanomorphing with ultrafast lasers may have a significant role in direct write stamp production. Surface conditions play a critical role in the ablative properties of materials. We have conducted femtosecond laser (pulse duration;120 fs, wavelength;780 nm) threshold studies of silicon with the native oxide and silicon with atomically clean surfaces in an ultra-high vacuum environment. We have discovered that a -1.5 nm thick oxide layer can alter the ablation threshold of Si (100) by 25 ± 5%. Additionally, our work has shown that collateral damage can be controlled on the nanoscale. Transmission electron microscopy (TEM) images of femtosecond laser machined holes in Si (100) show that collateral damage extends only 10 nm from the edge. © 2004 Materials Research Society.

关键词： Ultrafast phenomena

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