60,624 research outputs found
Redundancy Allocation of Partitioned Linear Block Codes
Most memories suffer from both permanent defects and intermittent random
errors. The partitioned linear block codes (PLBC) were proposed by Heegard to
efficiently mask stuck-at defects and correct random errors. The PLBC have two
separate redundancy parts for defects and random errors. In this paper, we
investigate the allocation of redundancy between these two parts. The optimal
redundancy allocation will be investigated using simulations and the simulation
results show that the PLBC can significantly reduce the probability of decoding
failure in memory with defects. In addition, we will derive the upper bound on
the probability of decoding failure of PLBC and estimate the optimal redundancy
allocation using this upper bound. The estimated redundancy allocation matches
the optimal redundancy allocation well.Comment: 5 pages, 2 figures, to appear in IEEE International Symposium on
Information Theory (ISIT), Jul. 201
New constructions of WOM codes using the Wozencraft ensemble
In this paper we give several new constructions of WOM codes. The novelty in
our constructions is the use of the so called Wozencraft ensemble of linear
codes. Specifically, we obtain the following results.
We give an explicit construction of a two-write Write-Once-Memory (WOM for
short) code that approaches capacity, over the binary alphabet. More formally,
for every \epsilon>0, 0<p<1 and n =(1/\epsilon)^{O(1/p\epsilon)} we give a
construction of a two-write WOM code of length n and capacity
H(p)+1-p-\epsilon. Since the capacity of a two-write WOM code is max_p
(H(p)+1-p), we get a code that is \epsilon-close to capacity. Furthermore,
encoding and decoding can be done in time O(n^2.poly(log n)) and time
O(n.poly(log n)), respectively, and in logarithmic space.
We obtain a new encoding scheme for 3-write WOM codes over the binary
alphabet. Our scheme achieves rate 1.809-\epsilon, when the block length is
exp(1/\epsilon). This gives a better rate than what could be achieved using
previous techniques.
We highlight a connection to linear seeded extractors for bit-fixing sources.
In particular we show that obtaining such an extractor with seed length O(log
n) can lead to improved parameters for 2-write WOM codes. We then give an
application of existing constructions of extractors to the problem of designing
encoding schemes for memory with defects.Comment: 19 page
Programmable image associative memory using an optical disk and a photorefractive crystal
The optical disk is a computer-addressable binary storage medium with very high capacity. More than 10^10 bits of information can be recorded on a 12-cm-diameter optical disk. The natural two-dimensional format of the data recorded on an optical disk makes this medium particularly attractive for the storage of images and holograms, while parallel access provides a convenient mechanism through which such data may be retrieved. In this paper we discuss a closed-loop optical associative memory based on the optical disk. This system incorporates image correlation, using photorefractive media to compute the best association in a shift-invariant fashion. When presented with a partial or noisy version of one of the images stored on the optical disk, the optical system evolves to a stable state in which those stored images that best match the input are temporally locked in the loop
Tagged repair techniques for defect tolerance in hybrid nano/CMOS architecture
We propose two new repair techniques for hybrid nano/CMOS computing architecture with lookup table based Boolean logic. Our proposed techniques use tagging mechanism to provide high level of defect tolerance and we present theoretical equations to predict the repair capability including an estimate of the repair cost. The repair techniques are efficient in utilization of spare units and capable of targeting upto 20% defect rates, which is higher than recently reported repair techniques
Does OO sync with the way we think?
Given that corrective-maintenance costs already dominate the software life cycle and look set to increase significantly, reliability in the form of reducing such costs should be the most important software improvement goal. Yet the results are not promising when we review recent corrective-maintenance data for big systems in general and for OO in particular-possibly because of mismatches between the OO paradigm and how we think
System Dynamics Modelling of the Processes Involving the Maintenance of the Naive T Cell Repertoire
The study of immune system aging, i.e. immunosenescence, is a relatively new
research topic. It deals with understanding the processes of immunodegradation
that indicate signs of functionality loss possibly leading to death. Even
though it is not possible to prevent immunosenescence, there is great benefit
in comprehending its causes, which may help to reverse some of the damage done
and thus improve life expectancy. One of the main factors influencing the
process of immunosenescence is the number and phenotypical variety of naive T
cells in an individual. This work presents a review of immunosenescence,
proposes system dynamics modelling of the processes involving the maintenance
of the naive T cell repertoire and presents some preliminary results.Comment: 6 pages, 2 figures, 1 table, 9th Annual Workshop on Computational
Intelligence (UKCI 2009), Nottingham, U
Coding scheme for 3D vertical flash memory
Recently introduced 3D vertical flash memory is expected to be a disruptive
technology since it overcomes scaling challenges of conventional 2D planar
flash memory by stacking up cells in the vertical direction. However, 3D
vertical flash memory suffers from a new problem known as fast detrapping,
which is a rapid charge loss problem. In this paper, we propose a scheme to
compensate the effect of fast detrapping by intentional inter-cell interference
(ICI). In order to properly control the intentional ICI, our scheme relies on a
coding technique that incorporates the side information of fast detrapping
during the encoding stage. This technique is closely connected to the
well-known problem of coding in a memory with defective cells. Numerical
results show that the proposed scheme can effectively address the problem of
fast detrapping.Comment: 7 pages, 9 figures. accepted to ICC 2015. arXiv admin note: text
overlap with arXiv:1410.177
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