Recent years have witnessed a growing interest in the study of neuralnetworks. A lot of work has been on understanding how various computational problems can be solved adopting these models. This paper describes an a...
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Recent years have witnessed a growing interest in the study of neuralnetworks. A lot of work has been on understanding how various computational problems can be solved adopting these models. This paper describes an asynchronous feedback neuralnetwork, the photon event identification problem in an astrophysics experiment, and shows some promising results.< >
In this paper we investigate the application of an artificial neuralnetwork to the computation of the instantaneous observer's heading in a static environment. This parameter has an important role in vision-based...
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ISBN:
(纸本)0819415472
In this paper we investigate the application of an artificial neuralnetwork to the computation of the instantaneous observer's heading in a static environment. This parameter has an important role in vision-based collision avoidance systems and relies upon accurately locating the focus of expansion (FOE) associated with the radial optical flow pattern arising as a consequence of the translational component of motion. The approach proposed in this paper is based on a feed-forward neuralnetwork able to compute the image coordinates of the FOE. It is assumed that the input signals are supplied to the network by a sensorial module computing the optical flow associated with a sequence of time-varying images of the viewed scene. A number of experiments have been performed both for theoretical and for realistic optical flow fields. In this latter real-world experiments the input sensorial module has been simulated through an Hopfield network. Experimental results show that the proposed neural architecture is able to recover the FOE position of testing flow fields with a mean error of 0.1 pixels for exact theoretical motion fields. Moreover it seems resistant to noise and its performances appear appreciable also in real world contexts.
Lexical combination presents a number of intriguing problems for cognitive science. By studying the empirical phenomena of combination we can derive constraints on models of the representation of individual lexical it...
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ISBN:
(纸本)0819415472
Lexical combination presents a number of intriguing problems for cognitive science. By studying the empirical phenomena of combination we can derive constraints on models of the representation of individual lexical items. One particular phenomenon that symbolic models have been unable to accommodate is `semantic interaction'. Medin & Shoben (1988) have shown that properties associated with nouns by subjects vary with the choice of adjective. For example, wooden spoons are not just made of a different material: the phrase is interpreted as denoting a `larger' object. However, the adjective wooden is not generally held to carry implications as to size. We report experimental results showing similar effects across a range of properties for a single adjective in combination with different nouns from a single semantic field. It is this more radical dependence of interpretative features on lexical partners that we term `semantic interaction'. The phenomenon described by Medin and Shoben cannot be accounted for by the Selective Modification model, the most complete model hitherto. We show that a case-based reasoning system could account for earlier data because of the particular examples chosen, but that such a model could not handle semantic interaction. A neuralnetwork system is presented that does handle semantic interaction.
neuralnetworks require VLSI implementations for on-board systems. Size and real-time considerations show that on-chip learning is necessary for a large range of applications. A flexible digital design is preferred he...
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neuralnetworks require VLSI implementations for on-board systems. Size and real-time considerations show that on-chip learning is necessary for a large range of applications. A flexible digital design is preferred here to more compact analog or optical realizations. As opposed to many current implementations, the two-dimensional systolic array system presented here is an attempt to define a novel computer architecture inspired by neurobiology. It is composed of generic building blocks for basic operations rather than predefined neuralmodels. A full custom VLSI design of a first prototype has demonstrated the efficacity of this design. A complete board dedicated to Hopfield's model has been designed using these building blocks. Beyond the very specific application presented here, the underlying principles can be used for designing efficient hardware for most neuralnetworkmodels.
Optics has increasingly been used to improve the performance of computing systems. This is most evident in the field of optical interconnects, but the advent of new devices like micro laser arrays, SEED devices and ot...
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ISBN:
(纸本)0819412309
Optics has increasingly been used to improve the performance of computing systems. This is most evident in the field of optical interconnects, but the advent of new devices like micro laser arrays, SEED devices and other components that allow the exploitation of the natural parallelism of Optics are promising inroads of optics into computing functions themselves. In recent years much progress has been made in understanding the relationships between various invariant pattern techniques, in particular how the optimization of one performance parameter limits the optimization of another. Paradoxically, the development of opticalneuralnetworks has also spurred the development of optical correlators, because correlator-based opticalneuralnetwork architectures are among the most practical, allowing a wide variety of neuralmodels such as back-propagation, adaptive resonance theory and competitive learning to be implemented optically.
The non-ideal behavior of analog integrated circuits make it necessary that Artificial neuralnetwork (ANN) systems be evaluated for the effect of error due to the non-idealities on its performance, before they are im...
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ISBN:
(纸本)0819412015
The non-ideal behavior of analog integrated circuits make it necessary that Artificial neuralnetwork (ANN) systems be evaluated for the effect of error due to the non-idealities on its performance, before they are implemented in analog hardware. In this paper we describe a procedure for automatically evaluating a given ANN system, described in the form of a Data Flow Graph (DFG). The equations required for the quantitative evaluation are extracted from the DFG description using symbolic computation techniques. Optimization methods are applied for generating bounds on the maximum values of error that can be associated with each circuit block. The generated bounds are put back to behavioral models of individual circuits blocks in the design library, to help screening viable alternatives and to generate circuit level specifications. The methodology forms part of a design automation environment that helps to map ANN systems to hardware interconnection descriptions.
A gray level discrete associative memory (GLDAM) neuralnetwork using interpattern association (IPA) model is presented. By decomposing a gray level pattern into bipolar/binary modes of subpatterns, a GLDAM can be con...
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ISBN:
(纸本)0819410128
A gray level discrete associative memory (GLDAM) neuralnetwork using interpattern association (IPA) model is presented. By decomposing a gray level pattern into bipolar/binary modes of subpatterns, a GLDAM can be constructed. Although GLDAM improves the information capacity of the neural net, the decomposition process introduces sparse allocation in memory matrix, which affects the performance of the neural net. Computer simulated results for the Hopfield and the IPA models are provided, in which we have shown that the IPA GLDAM performs better.
Training by adaptive gain (TAG) neuralnetwork model, which had been developed for optical implementation of large-scale artificial neuralnetworks, is further extended for better performance and its feasibility is de...
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ISBN:
(纸本)0819410128
Training by adaptive gain (TAG) neuralnetwork model, which had been developed for optical implementation of large-scale artificial neuralnetworks, is further extended for better performance and its feasibility is demonstrated by a small-scale electro-optic implementation. For fully interconnected single-layer neuralnetworks with N input and M output neurons the modified TAG model contains two different types of interconnections, i.e., MN fixed global interconnections and βN + M adaptive local interconnections. For the original TAG model the number of adaptive local interconnections β was set to 1, and the interconnections were understood as adaptive gain. For 2-dimensional input and output patterns the fixed global interconnections may be achieved by page-oriented holograms, and the adaptive local interconnections by spatial light modulators. The original and modified TAG models require much less adaptive elements than the popular perceptron model with fully adaptive global interconnections, and provide possibilities of implementing large-scale artificial neuralnetworks with some sacrifice in performance. The training algorithm is based on gradient descent and error back-propagation, and is easily extensible to multi-layer architecture. Computer simulation and electro-optic implementation demonstrate much better performance of the modified TAG model compared to the original TAG model.
Research in the last decade emphasized the potential of designing adaptive pattern recognition classifiers based on algorithms using multi-layered artificial neural nets. The greatest potential in such endeavors was a...
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ISBN:
(纸本)0819413267
Research in the last decade emphasized the potential of designing adaptive pattern recognition classifiers based on algorithms using multi-layered artificial neural nets. The greatest potential in such endeavors was anticipated to be not only in the adaptivity but also in the high-speed processing through massively parallel VLSI implementation and opticalcomputing. Computational advantages of such algorithms have been demonstrated in a number of papers. neuralnetworks particularly the self-organizing types have been found quite suitable crisp pattern for clustering of unlabeled datasets. The generalization of Kohonen-type learning vector quantization (LVQ) clustering algorithm to fuzzy LVQ clustering algorithm and its equivalence to fuzzy c-means has been clearly demonstrated recently. On the other hand, Carpenter/Grossberg's ART-type self organizing neuralnetworks have been modified to perform fuzzy clustering by a number of researches in the past few years. The performance of such neuro-fuzzy models in clustering unlabeled data patterns is addressed in this paper. A recent development of a new similarity measure and a new learning rule for updating the centroid of the winning cluster in a fuzzy ART-type neuralnetwork is also described. The capability of the above neuro-fuzzy model in better partitioning of datasets into clusters of any shape is demonstrated.
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