16600244
Heterogeneous integration of biomimetic acoustic microsystems
We discuss biologically inspired devices and architectures for acoustic processing microsystems. We exploit state of the art integrated microsystems technologies to heterogeneously integrate electronics and micromechanical structures for acoustic sensing and signal processing.
14474778
Spike Timing-Dependent Plasticity in the Address Domain
Address-event representation (AER), originally proposed as a means to communicate sparse neural events between neuromorphic chips, has proven efficient in implementing large-scale networks with arbitrary, configurable synaptic connectivity. In this work, we further extend the functionality of AER to implement arbitrary, configurable synaptic plasticity in the address domain. As proof of concept, we implement a biologically inspired form of spike timing-dependent plasticity (STDP) based on relative timing of events in an AER framework. Experimental results from an analog VLSI integrate-and-fire network demonstrate address domain learning in a task that requires neurons to group correlated inputs.
6053956
A low-power correlation-derivative CMOS VLSI circuit for bearing estimation
We present a CMOS integrated circuit (IC) for bearing estimation in the low-audio range that performs a correlation derivative approach in a 0.35-/spl mu/m technology. The IC calculates the bearing angle of a sound source with a mean variance of one degree in a 360/spl deg/ range using four microphones: one pair is used to produce the indication and the other to define the quadrant. An adaptive algorithm decides which pair to use depending on the direction of the incoming signal, in such a way to obtain the best estimate. The IC contains two blocks with 104 stages each. Every stage has a delay unit, a block to reduce the clock speed, and a 10-bit UP/DN counter. The IC measures 2 mm by 2.4 mm, and dissipates 600 /spl mu/W at 3.3 V and 200 kHz. It is purely digital and uses a one-bit quantization of the input signals.
36729490
Energy efficiency in a channel model for the spiking axon
Abstract We examine the spiking axon as a communication channel. We develop a first principles channel model that encompasses the noise in the axon, which manifests itself as spike jitter, and the power consumption, which arises from the activity of the Na + –K + pump. This model enables us to examine the trade-off between the information rate and power consumption. Using parameters from the frog myelinated axon, we determine the spike rate that corresponds to the maximum energy efficiency. This spike rate is consistent with experimental observations, which suggests that neural communication may have developed to maximize energy efficiency rather than information rate alone.
30699245
A low-power CMOS integrated circuit for bearing estimation
We present the design and testing of a micropower integrated circuit for the estimation of the bearing angle of a sound source with respect to a pair of microphones. The algorithm is based on a modified binary cross-correlation approach suitable for low-power operation. The circuit has been tested and operates at 600 /spl mu/W at performance levels matching theoretical simulations.
36350590
Spike communication of dynamic stimuli: rate decoding versus temporal decoding
Abstract We compare two methods for extracting information about a dynamic analog stimulus from a spike train: a rate decoder, which is based on the number of spikes in a counting window, and a temporal decoder, which is based on interspike intervals. We derive analytical expressions for the distortion between a stimulus current that drives an integrate-and-fire spike generator and a reconstruction of that current based on the spike train. We consider intrinsic distortion, which arises due to the limitations of spike coding, and extrinsic distortion, which is due to explicit alterations of the spike train. We find that in the absence of extrinsic distortion, the temporal decoder is superior to the rate decoder. In the presence of extrinsic distortion, the temporal decoder is preferred when low latency is required, but the rate decoder is preferred when the latency requirement is relaxed.
12319077
Paper position sensing
We describe position sensing algorithms used in an airjet paper moving system built at Xerox PARC. The algorithms combine inputs from optical sensors and compute the rectangle best fitting the data. We consider two different types of sensors: fax scan bars and disk-shaped area sensors. Our algorithms proved to be quite effective both in simulation and in actual use.
26906105
Trustworthy Paper Documents
In the first part of this paper, we propose a watermarking method for text documents that is less vulnerable to attacks than previous methods. In the second part, we propose a method for protecting the actual content of the document. In a section of independent interest, we discuss the interplay between error-correcting codes and steganography.
195349341
A global approach to automatic solution of jigsaw puzzles
4796791
A global approach to automatic solution of jigsaw puzzles
We present a new algorithm for automatically solving jigsaw puzzles by shape alone. The algorithm can solve more difficult puzzles than could be solved before, without the use of backtracking or branch-and-bound. The algorithm can handle puzzles in which pieces border more than four neighbors, and puzzles with as many as 200 pieces. Our overall strategy follows that of previous algorithms but applies a number of new ideas, such as robust fiducial points, "highest- confidence-first" search, and frequent global reoptimization of partial solutions.
9584467
Improved Ranking Functions for Protein and Modification-Site Identifications
There are a number of computational tools for assigning identifications to peptide tandem mass spectra, but many fewer tools for the crucial next step of integrating spectral identifications into higher-level identifications, such as proteins or modification sites. Here we describe a new program called ComByne for scoring and ranking higher-level identifications. We compare ComByne to existing algorithms on several complex biological samples, including a sample of mouse blood plasma spiked with known concentrations of human proteins. A Web interface to our software is at http://bio.parc.xerox.com.