6161480
Homeostasis in a Silicon Integrate and Fire Neuron
In this work, we explore homeostasis in a silicon integrate-and-fire neuron. The neuron adapts its firing rate over long time periods on the order of seconds or minutes so that it returns to its spontaneous firing rate after a lasting perturbation. Homeostasis is implemented via two schemes. One scheme looks at the presynaptic activity and adapts the synaptic weight depending on the presynaptic spiking rate. The second scheme adapts the synaptic "threshold" depending on the neuron's activity. The threshold is lowered if the neuron's activity decreases over a long time and is increased for prolonged increase in postsynaptic activity. Both these mechanisms for adaptation use floating-gate technology. The results shown here are measured from a chip fabricated in a 2-µm CMOS process.
14557838
AER Auditory Filtering and CPG for Robot Control
Address-event-representation (AER) is a communication protocol for transferring asynchronous events between VLSI chips, originally developed for bio-inspired processing systems (for example, image processing). The event information in an AER system is transferred using a high-speed digital parallel bus. This paper presents an experiment using AER for sensing, processing and finally actuating a robot. The AER output of a silicon cochlea is processed by an AER filter implemented on a FPGA to produce rhythmic walking in a humanoid robot (Redbot). We have implemented both the AER rhythm detector and the central pattern generator (CPG) on a Spartan II FPGA which is part of a USB-AER platform developed by some of the authors
9506912
Quantifying Input and Output Spike Statistics of a Winner-Take-All Network in a Vision System
Event-driven spike-based processing systems offer new possibilities for real-time vision. Signals are encoded asynchronously in time thus preserving the time information of the occurrence of an event. The paper examines this form of coding using experimental data from a multi-layered multi-chip system which consists of an artificial retina, a convolution filter bank and a winner-take-all network which detect the position of a moving object. The spike outputs of the convolution stage can be described by an inhomogeneous Poisson distribution of Gaussian profile, although the underlying building blocks are completely deterministic and exhibit only a small amount of variation. The authors discuss a method for measuring the accuracy of the asynchronous spiking representation in both time and value, thereby quantifying the performance of the winner-take-all network in determining the position of a ball rotating in front of the system.
1744079
Object-based analog VLSI vision circuits
Describes two analog VLSI chips that perform object-based computations. The first chip computes length of various contours in an image and the second chip performs figure-ground separation of a scene.<<ETX>>
1310843
AER EAR: A Matched Silicon Cochlea Pair With Address Event Representation Interface
In this paper, we present an analog integrated circuit containing a matched pair of silicon cochleae and an address event interface. Each section of the cochlea, modeled by a second-order low-pass filter, is followed by a simplified inner hair cell circuit and a spiking neuron circuit. When the neuron spikes, an address event is generated on the asynchronous data bus. We present the results of the chip characterization and the results of an interaural time difference based sound localization experiment using the address event representation (AER) EAR. The chip was fabricated in a 3-metal 2-poly 0.5-mum CMOS process
14708614
Programmable synaptic weights for an aVLSI network of spiking neurons
We describe a spiking neuronal network which allows local synaptic weights to be assigned to individual synapses. In previous implementations of neuronal networks, the biases that control the parameters of a particular synapse are global to all synapses of the same type regardless of the target neuron. In this new implementation, the parameters for a synapse are set by on-chip digital-analog-converter (DAC) circuits, and the DACs are updated before the selected synapses are activated. Results from the fabricated chip show that the local weights are programmable and the DACs settle in the order of microseconds. These on-chip DACs allow the user to program a selected synaptic weight for connections between neurons and they can also be used for mismatch calibration
14652555
Adding multi-class routing into the DiffServ architecture
To alleviate the problem of high priority traffic hogging of all the available network capacity and to optimize the network traffic in the DiffServ network, we introduce the multi-class routing (MCR) scheme into the DiffServ architecture. The MCR scheme that builds multiple routing tables in the DiffServ routers forms the MCR DiffServ architecture. In this paper, the MCR DiffServ architecture focuses on the intra-DS domain. Different MCR approaches that include a static approach and dynamic approaches can be used for the MCR DiffServ system. We extend the OSPF protocol in order to build up more than one routing table in each MCR DiffServ system. According to the extensions to OSPF, we have implemented the static MCR approach for the MCR DiffServ system on the basis of the open source Zebra software.
14515232
An investigation of the approach to specification-based program review through case studies
Software review is an effective means to enhance the quality of software systems. However, traditional review methods emphasize the importance of the way to organize reviews and rely on the quality of the reviewers' experience and personal skills. In this paper we propose a new approach to rigorously reviewing programs based on their formal specifications. The fundamental idea of the approach is to use a formal specification as a standard to check whether all the required functions and properties in the specification are correctly implemented by its program. To help investigate the effectiveness and the weakness of the approach, we conduct two case studies of reviewing two program systems that implement the same formal specification of "A Research Management Policy" using different strategies, and present the evaluation of the case studies. The results show that the review approach is effective in detecting faults when the reviewer is different from the programmer, but less effective when the reviewer is the same as the programmer.
30881235
Criteria for generating specification-based tests
This paper presents general criteria for generating test inputs from state-based specifications. Software testing can only be formalized and quantified when a solid basis for test generation can be defined. Formal specifications of complex systems represent a significant opportunity for testing because they precisely describe what functions the software is supposed to provide in a form that can easily be manipulated. These techniques provide coverage criteria that are based on the specifications, and are made up of several parts, including test prefixes that contain inputs necessary to put the software into the appropriate state for the test values. The test generation process includes several steps for transforming specifications to tests. Empirical results from a comparative case study application of these criteria are presented.
11533048
RFID Data Processing with a Data Stream Query Language
RFID technology provides significant advantages over traditional object-tracking technologies and is increasingly adopted and deployed in real applications. RFID applications generate large volume of streaming data, which have to be automatically filtered, processed, and transformed into semantic data, and integrated into business applications. Indeed, RFID data are highly temporal, and RFID observations form complex temporal event patterns which can be very different for various RFID applications. Thus, it is desirable to have a general RFID data processing framework with a powerful language, for the end users to express a variety of queries on RFID data streams, as well as detecting complex events patterns. While data stream management systems (DSMSs) are emerging for optimized stream data processing, they usually lack the language construct support for temporal event detection. In this paper, we discuss a stream query language to provide comprehensive temporal event detection, through temporal operators and extension of sliding-window constructs. With the integration of temporal event detection, a DSMS has the capability to serve as a powerful system for RFID data processing.
1976770
Self-independent Petri Nets for Distributed Systems
We propose that asynchronous mechanism for communication should be considered as a primitive for semantic models of distributed systems in contrast to the synchronous mechanism (hand-shaking) of CSP (Hoare, 1985) and of CCS (Milner, 1989). By doing so, we present an approach to producing a deadlock-free system, and give a denotational model for CCS in a non-interleaving fashion.