1,721,042 research outputs found
Improving 3D NAND Flash Memories Reliability: a Cross-Layer Perspective
No full textThe 3D NAND Flash memory technology is the main building block of storage architectures such as multimedia cards and Solid-State Drives. Applications ranging from mobile to high-performance computing are continuously calling for an increased storage density, requiring massive scaling efforts at the device and array level. This leads to a natural degradation of the functional metrics of the technology while exposing new reliability issues that jeopardize the inherent memory trade-off with performance. A simple device optimization would be insufficient to tackle the problem. In this work, we show through some case studies how a cross-layer approach spanning from devices and circuits to system-level optimizations is mandatory for future storage systems development
Editorial for the special issue on flash memory devices
No full textFlash memory devices represented a breakthrough in the storage industry since their inception in the mid-1980s, and innovation is still ongoing after more than 35 years. This Special Issue provides insight on and advancements in Flash memory devices
Point selection: A new comparison scheme for size functions (with an application to monogram recognition)
No full textA new paradigm for the comparison of size functions is presented; it stresses the relevance of the "angular points" of the functions, and gives greater value to the stable ones. A simple example of classification of monograms (88 elements in the training set, 88 in the test set, for 22 classes, with a hit rate of 78%) is given, and a current enhancement of the experiment is described
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
LDPC Soft Decoding with Improved Performance in 1X-2X MLC and TLC NAND Flash-Based Solid State Drives
No full textThe reliability of non-volatile NAND flash memories is reaching critical levels for traditional error detection and correction. Therefore, to ensure data trustworthiness in nowadays NAND flash-based Solid State Drives, it is essential to exploit powerful correction algorithms such as the Low Density Parity Check. However, the burdens of this approach materialize in a disk performance reduction. In this work a standard decoding approach is compared with an optimized solution exploiting hardware resources available in NAND flash chips. The simulation results on 2X, 1X and mid-1X MLC and TLC NAND flash-based Solid State Drives in terms of disk bandwidth, average latency, and Quality of Service favor the adoption of the presented solution in different host scenarios and realistic workloads. The proposed solution is particularly effective when high error correction interventions and read- or write-intensive workloads are considered
Investigating 3D NAND Flash Read Disturb Reliability with Extreme Value Analysis
No full textThe storage systems relying on the 3D NAND Flash technology require an extensive modeling of their reliability in different working corners. This enables the deployment of system-level management routines that do not compromise the overall performance and reliability of the system itself. Dedicated parametric statistical models have been developed so far to capture the evolution of the memory reliability, although limiting the description to an average behavior rather than extreme cases that can disrupt the storage functionality. In this work, we validate the application of an extreme statistics tool, namely the Points-Over-Threshold method, to characterize the read disturb reliability of a 3D NAND Flash chip. Such technique proved that the die reliability characterized through extreme events analysis can be predicted using a low number of samples and generally holds good prediction features for distribution tail events
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