90,306 research outputs found
Smart-Pixel Cellular Neural Networks in Analog Current-Mode CMOS Technology
This paper presents a systematic approach to design CMOS chips with concurrent picture acquisition and processing capabilities. These chips consist of regular arrangements of elementary units, called smart pixels. Light detection is made with vertical CMOS-BJT’s connected in a Darlington structure. Pixel smartness is achieved by exploiting the Cellular Neural Network paradigm [1], [2], incorporating at each pixel location an analog computing cell which interacts with those of nearby pixels. We propose a current-mode implementation technique and give measurements from two 16 x 16 prototypes in a single-poly double-metal CMOS n-well 1.6-µm technology. In addition to the sensory and processing circuitry, both chips incorporate light-adaptation circuitry for automatic contrast adjustment. They obtain smart-pixel densities up to 89 units/mm2, with a power consumption down to 105 µW/unit and image processing times below 2 µs
Magnetic Cellular Nonlinear Network with Spin Wave Bus for Image Processing
We describe and analyze a cellular nonlinear network based on magnetic
nanostructures for image processing. The network consists of magneto-electric
cells integrated onto a common ferromagnetic film - spin wave bus. The
magneto-electric cell is an artificial two-phase multiferroic structure
comprising piezoelectric and ferromagnetic materials. A bit of information is
assigned to the cell's magnetic polarization, which can be controlled by the
applied voltage. The information exchange among the cells is via the spin waves
propagating in the spin wave bus. Each cell changes its state as a combined
effect of two: the magneto-electric coupling and the interaction with the spin
waves. The distinct feature of the network with spin wave bus is the ability to
control the inter-cell communication by an external global parameter - magnetic
field. The latter makes possible to realize different image processing
functions on the same template without rewiring or reconfiguration. We present
the results of numerical simulations illustrating image filtering, erosion,
dilation, horizontal and vertical line detection, inversion and edge detection
accomplished on one template by the proper choice of the strength and direction
of the external magnetic field. We also present numerical assets on the major
network parameters such as cell density, power dissipation and functional
throughput, and compare them with the parameters projected for other
nano-architectures such as CMOL-CrossNet, Quantum Dot Cellular Automata, and
Quantum Dot Image Processor. Potentially, the utilization of spin waves
phenomena at the nanometer scale may provide a route to low-power consuming and
functional logic circuits for special task data processing
A fine-grain time-sharing Time Warp system
Although Parallel Discrete Event Simulation (PDES) platforms relying on the Time Warp (optimistic) synchronization
protocol already allow for exploiting parallelism, several techniques have been proposed to
further favor performance. Among them we can mention optimized approaches for state restore, as well as
techniques for load balancing or (dynamically) controlling the speculation degree, the latter being specifically
targeted at reducing the incidence of causality errors leading to waste of computation. However, in
state of the art Time Warp systems, events’ processing is not preemptable, which may prevent the possibility
to promptly react to the injection of higher priority (say lower timestamp) events. Delaying the processing
of these events may, in turn, give rise to higher incidence of incorrect speculation. In this article we present
the design and realization of a fine-grain time-sharing Time Warp system, to be run on multi-core Linux
machines, which makes systematic use of event preemption in order to dynamically reassign the CPU to
higher priority events/tasks. Our proposal is based on a truly dual mode execution, application vs platform,
which includes a timer-interrupt based support for bringing control back to platform mode for possible CPU
reassignment according to very fine grain periods. The latter facility is offered by an ad-hoc timer-interrupt
management module for Linux, which we release, together with the overall time-sharing support, within the
open source ROOT-Sim platform. An experimental assessment based on the classical PHOLD benchmark and
two real world models is presented, which shows how our proposal effectively leads to the reduction of the
incidence of causality errors, as compared to traditional Time Warp, especially when running with higher
degrees of parallelism
- …