1,720,954 research outputs found
Metodología de selección de caminos críticos para circuitos nanométricos CMOS tolerantes a envejecimiento debido a NBTI
Get PDFEl continuo escalado tecnológico de los dispositivos MOSFET ha permitido
que los circuitos integrados VLSI alcancen una mayor densidad de integración
y velocidad de operación, lo cual ha llevado a un incremento en la demanda de
circuitos electrónicos, especialmente los circuitos digitales. Sin embargo, sobre el
régimen de dimensiones nanométricas el impacto de algunos efectos que degradan
el rendimiento del dispositivo es más significativo, disminuyendo su tiempo de vida
útil. Los principales mecanismos de envejecimiento que afectan el rendimiento
son el NBTI, HCI y TDDBD, siendo el NBTI identificado como el factor predominante
de envejecimiento en transistores PMOS. El efecto que tiene el NBTI es el
de aumentar la magnitud del voltaje umbral del transistor a través del tiempo,
dependiendo de las condiciones de operación del dispositivo como temperatura y
tensión de alimentación. El incremento del voltaje umbral ocasiona que el retardo
de propagación de los caminos lógicos de señal en un circuito digital se incremente.
Si este retardo sobrepasa las restricciones de temporización se presentará una falla
en el sistema que en algunas aplicaciones como en el área automotríz o aeroespacial
son inaceptables. Para tolerar el incremento del retardo de propagación
debido al envejecimiento de los dispositivos, convencionalmente se introduce un
tiempo adicional en el período de reloj que funciona como márgen de seguridad
(también llamado banda de guarda). Sin embargo, introducir márgenes de seguridad
en el período de reloj no permite obtener un óptimo rendimiento del circuito
durante su tiempo de vida inicial
Reliability analysis and improvement of nanoscale CMOS digital circuits
Get PDFReliability degradation due to transistor aging is a major challenge in the design of digital integrated circuits for current and future technology nodes. Bias Temperature Instability (BTI) is the dominant aging mechanisms in digital circuits. BTI gradually increases the device's threshold voltage (Vth) over the lifetime, which in turn degrades circuit speed, and ultimately, it may cause a faulty operation. Circuit performance degradation due to BTI is highly dependent on the operating conditions such as the executed workloads by the circuit and the operating temperature. Moreover, variability in devices parameter due to process variations aggravate the reliability issues. These effects need to be properly accounted during circuit design phase to obtain electronic products with improved lifetime. Conventional worst-case one-time guardbans to deal with aging due to BTI are becoming too large with technology scaling, which leads to conservative designs with reduced performance. This thesis addresses BTI aging issues from two different perspectives: Aging Monitoring: Aging sensors are introduced in the circuit critical paths (CP) in order to detect when they are close to violate timing speci_cations due to BTI. Then, failure-prevention actions (i.e. increase system clock period) can take place. This thesis proposes a methodology to efficiently identify, at an early design phase, the critical paths of the circuit that should be monitored for reliable on-line aging tracking. The major challenges addressed for critical path selection are the uncertainty caused by process parameters variations, the uncertainty on spatial correlation between gates since gate placement in the layout is unknown at early design phase, and the uncertainty of the operating workload of the circuit, which is unknown in advance at the design phase. Reliable Circuit Design: Among the gates that belong to the critical paths of a circuit, some of them are more efcient to be re-sized to compensate aging degradation. This thesis proposes a circuit design methodology to reduce the guardband required for a circuit by smart selection an sizing of the circuit's critical gates. Gate selection metrics are proposed to guide the sizing process of the circuits. One of the most important parameters taken into account by the metrics is the statistical path delay sensitivity to gate sizing, which depends on process variations, spatial correlation between gates, and the BTI degradation of the device
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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