5895615
Range estimation on a robot using neuromorphic motion sensors
Neuromorphic motion sensors using analog very large scale integrated technology are attractive for use on battery powered robots which require a low payload. Their features include low power consumption, continuous computation, light-weight, and robustness to different light and contrast conditions. Their outputs are not compatible with controllers that require precise measurements from their sensors. We describe a preliminary investigation into neural architectures that can translate information from these type of sensors into an output suitable for controlling the motor outputs of a robot. In this work, we use a neural network to produce an output that is similar to the range measurements of infrared range sensors, and we use this output to guide the behavior of the robot in a collision-avoidance task. © 2004 Elsevier B.V. All rights reserved.
18592302
A Winner-Take-All Circuit with Controllable Soft Max Property
I describe a silicon network consisting of a group of excitatory neurons and a global inhibitory neuron. The output of the inhibitory neuron is normalized with respect to the input strengths. This output models the normalization property of the wide-field direction-selective cells in the fly visual system. This normalizing property is also useful in any system where we wish the output signal to code only the strength of the inputs, and not be dependent on the number of inputs. The circuitry in each neuron is equivalent to that in Lazzaro's winner-take-all (WTA) circuit with one additional transistor and a voltage reference. Just as in Lazzaro's circuit, the outputs of the excitatory neurons code the neuron with the largest input. The difference here is that multiple winners can be chosen. By varying the voltage reference of the neuron, the network can transition between a soft-max behavior and a hard WTA behavior. I show results from a fabricated chip of 20 neurons in a 1.2 µm CMOS technology.
1845062
Adaptive Retina with Center-Surround Receptive Field
Both vertebrate and invertebrate retinas are highly efficient in extracting contrast independent of the background intensity over five or more decades. This efficiency has been rendered possible by the adaptation of the DC operating point to the background intensity while maintaining high gain transient responses. The center-surround properties of the retina allows the system to extract information at the edges in the image. This silicon retina models the adaptation properties of the receptors and the antagonistic center-surround properties of the laminar cells of the invertebrate retina and the outer-plexiform layer of the vertebrate retina. We also illustrate the spatio-temporal responses of the silicon retina on moving bars. The chip has 59×64 pixels on a 6.9×6.8mm2 die and it is fabricated in 2 µm n-well technology.
12793172
Continuous-time adaptive delay system
We have developed an adaptive delay system that adjusts the delay of a delay element so that it matches the temporal disparity between the onset of two input signals. The delay is controlled either by an external bias voltage, or by an intrinsic signal derived from an adaptive block. The operation of the adaptive delay system is similar to that of a charge-pump phase-lock loop, with an extended lock-in range of more than 5 decades. Standard CMOS transistors are used in their subthreshold region. Experimental results from circuits fabricated in 2 /spl mu/m CMOS technology are in agreement with the analysis.<<ETX>>
6979172
Encoding the Temporal Statistics of Markovian Sequences of Stimuli in Recurrent Neuronal Networks
Encoding, storing, and recalling a temporal sequence of stimuli in a neuronal network can be achieved by creating associations between pairs of stimuli that are contiguous in time. This idea is illustrated by studying the behavior of a neural network model with binary neurons and binary stochastic synapses. The network extracts in an unsupervised manner the temporal statistics of the sequence of input stimuli. When a stimulus triggers the recalling process, the statistics of the output patterns reflects those of the input. If the sequence of stimuli is generated through a Markov process, then the network dynamics faithfully reproduces all the transition probabilities.
34951314
Spike synchronization in a network of silicon integrate-and-fire neurons
Spike-event based computational processing by neuronal networks depends on a variety of spatio-temporal mechanisms that are distributed across neuronal synapses, dendrites, and somata. The overall processing of spatio-temporal patterns of spike requires global temporal coherence between all these processes both within a neuron, and across all neurons of the network. We are evaluating the use of networks of hybrid analog-digital integrate-and-fire neurons, fabricated using VLSI, for studying real-time event-based processing. These hardware networks have the advantages of real-time operation, and inherent global synchronization by their analog implementation. However, one of the technical challenges in the operation of such networks is the unavoidable fabrication related variance between the different neurons of the network. Here we show that despite this variance, an important behavior of neuronal networks, spike synchronization, can be obtained from a simple network of VLSI neurons interconnected by lateral excitation and global inhibition.
11127695
The semantics of extended SOFL
SOFL (structured-object-based-formal language) has been extended to a formal object-oriented language and method while keeping its structured features. This extension allows powerful object-oriented reuse mechanisms, such as class inheritance and object composition, to be utilized in the early design phases. This paper presents the semantics for this extended SOFL, and further demonstrates the extendibility and reusability of the object-oriented semantic models of SOFL.
11824549
An approach to detecting domain errors using formal specification-based testing
Domain testing, a technique for testing software or portions of software dominated by numerical processing, is intended to detect domain errors that usually arise from incorrect implementations of desired domains. This paper describes our recent work aiming to provide support for revealing domain errors using formal specifications. In our approach, formal specifications serve as a means for domain modeling. We describe a strong domain testing strategy that guide testers to select a set of test points so that the potential domain errors can be effectively detected, and apply our approach in two case studies for test cases generation.
1673600
Inferring Data Transformation Rules to Integrate Semantic Web Services
OWL-S allows selecting, composing and invoking Web Services at different levels of abstraction: selection uses high level abstract descriptions, invocation uses low level grounding ones, while composition needs to consider both high and low level descriptions. In our setting, two Web Services are to be composed so that output from the upstream one is used to create input for the downstream one. These Web Services may have different data models but are related to each other through high and low level descriptions. 
 
Correspondences must be found between components of the upstream data type and the downstream ones. Low level data transformation functions may be required (e.g. unit conversions, data type conversions). The components may be arranged in different XML tree structures. Thus, multiple data transformations are necessary: reshaping the message tree, matching leaves by corresponding types, translating through ontologies, and calling conversion functions. Our prototype compiles these transformations into a set of data transformation rules, using our tableau-based ALC Description Logic reasoner to reason over the given OWL-S and WSDL descriptions, as well as the related ontologies. A resolution-based inference mechanism for running these rules is embedded in an inference queue that conducts data from the upstream to the downstream service, running the rules to perform the data transformation in the process.
1275297
Bridging Physical and Virtual Worlds: Complex Event Processing for RFID Data Streams
Advances of sensor and RFID technology provide significant new power for humans to sense, understand and manage the world. RFID provides fast data collection with precise identification of objects with unique IDs without line of sight, thus it can be used for identifying, locating, tracking and monitoring physical objects. Despite these benefits, RFID poses many challenges for data processing and management: i) RFID observations contain duplicates, which have to be filtered; ii) RFID observations have implicit meanings, which have to be transformed and aggregated into semantic data represented in their data models; and iii) RFID data are temporal, streaming, and in high volume, and have to be processed on the fly. Thus, a general RFID data processing framework is needed to automate the transformation of physical RFID observations into the virtual counterparts in the virtual world linked to business applications. In this paper, we take an event-oriented approach to process RFID data, by devising RFID application logic into complex events. We then formalize the specification and semantics of RFID events and rules. We demonstrate that traditional ECA event engine cannot be used to support highly temporally constrained RFID events, and develop an RFID event detection engine that can effectively process complex RFID events. The declarative event-based approach greatly simplifies the work of RFID data processing, and significantly reduces the cost of RFID data integration.
14954145
Interacting frameworks in Catalysis
In current OO design, most of the existing (semi-formal) methods use classes or objects as the basic unit of design. However it is increasingly recognised that classes are not the best focus for design. Typical design artefacts are about groups of objects and the way they interact In the Catalysis project, we use the term frameworks for descriptions of groups of objects, their relationships, division of responsibilities, and interactions. The power of frameworks lies in the fact that interactions can also occur at the level of frameworks. In a previous paper we defined a framework formally as a (first-order) many-sorted theory with a model theoretic semantics and showed how it can be represented using a pictorial notation for practical system development. However we considered only frameworks that do not interact with one another In this paper we discuss frameworks that interact with one another and show that such frameworks are very powerful tools for formal OO design.