1,721,095 research outputs found
Soft Errors Induced By Neutrons and Alpha Particles in System on Chips
Full text linkThis Manuscript presents a new low-cost test setup for the radiation tests of System on Chips composed of different functional modules of different nature. Particular attention is given to radiation experiments results of embedded SRAM cores, embedded logic cores and embedded microprocessor cores, highlighting the dissimilar test protocols required to characterize their sensitivity to radiation.
The main issues when testing a System on Chip are the cores reduced accessibility and the physical constraints test facilities may impose to the test setup. Manufacturers heavily employ Design for Testability techniques, based on built-in test structures, to enable exhaustive devices testing while minimizing application costs. We reused some of the Design for Testability built-in structures to deeply characterize the cores composing the System on Chip and the overall chip behaviours when exposed to radiation. Our strategy can be applied to any kind of integrated core, and we also present some guidelines on how built-in structures may be fruitfully applied to radiation experiments. Moreover, the monolithic shape of our test board makes it easy to be mounted in most of available particle accelerators chambers or radiation test facilities. As the test structures are built-in and thanks to the efficient interfaces strategy that takes advantage of both JTAG and Wrappers standards, tests are performed at high frequency, thus avoiding Single Event Transients underestimation, but without the need of high-speed connections between a host PC and the DUT, drastically reducing the overall setup costs.
This thesis also shows and discusses the results gained during massive radiation experiments campaigns on the available System on Chip manufactured by STMicroelectronics in a 90 nm CMOS technology. As device is meant to be part of a complex automotive design, it may be affected by ground level radiation. We then exposed the chips both to neutron and alpha particles fluxes. With our low-cost setup we measured the SRAM core cross section to alphas and neutrons, and found out that the former one is higher than the latter. We have also characterized the microprocessors behaviour when exposed to alphas. The static test stated that registers flip-flops have a higher radiation induced error rate with respect to code and user RAM one. This result is of great importance, and should be taken into account when building a fault-injection platform. To understand how the corruption of the different memory resources affects codes executions, we designed different benchmark codes and performed a dynamic test. Results demonstrate that, in a typical application, the bit-flips in the code RAM are definitely predominant with respect to the ones in registers. Moreover, we show how code RAM and register bits are not always critical, and their corruption does not necessarily propagate to outputs. Finally, we have considered hardening techniques efficiency and costs. In particular, we have studied how Design For Manufacturing layout modifications and Triple Module Redundancy affect the radiation sensitivity of microprocessors. We considered chips built with different Design For Manufacturing maturity levels, and experimental results demonstrate that an higher level of optimization enhances the resilience to alpha radiation. Hardening techniques, however, come to a cost. The decision on which hardening technique to adopt when building a complex device is a hard-earned trade-off between costs, performance and, of course, reliability. Mitigation strategies for a product then depends on its requirements and on its mission environment.Questa tesi presenta un innovativo setup a basso costo per effettuare dei test sotto radiazione di System on Chips in cui siano integrati moduli di diversa natura e con diverse funzionalità. In particolare sono stati svolti numerosi test sotto radiazione di memorie SRAM integrate, di moduli logici integrati e di microprocessori integrati, analizzando i diversi protocolli di test necessari per poter caratterizzare al meglio la loro sensibilità alla radiazione.
Uno dei problemi maggiori che si riscontrano quando si deve testare un System on Chip è la ridotta accessibilità dei vari moduli integrati e i vincoli fisici che devono essere rispettati per effettuare il test stesso e che rendono le procedure di analisi molto difficili. I costruttori, per riuscire a verificare la funzionalità dei vari moduli integrati, usano molto spesso delle tecniche chiamate Design for Testability bastate su strutture di test integrate che permettono un’esaustiva verifica della funzionalità dei moduli minimizzando allo stesso tempo i costi del test. Durante gli esperimenti presentati in questo lavoro abbiamo riutilizzato alcune strutture integrate del tipo Design for Testability per caratterizzare nel dettaglio sia tutti i singoli moduli che compongono un System on Chip che il comportamento globale del dispositivo quando viene esposto a radiazione. La strategia che è proposta in questa tesi può essere generalizzata e applicata a qualunque tipo di modulo integrato e sono presentati anche alcuni suggerimenti sul come applicare le strutture di test DfT agli esperimenti di radiazione. Quando si effettua un esperimenti di radiazione tipicamente ci sono diversi vincoli che, in base al laboratorio in cui gli esperimenti vengono eseguiti, possono essere imposti al setup di test. La scheda di test che abbiamo sviluppato ha una forma monolitica, che la rende facile da posizionare nella maggior parte delle camere di irraggiamento degli acceleratori di particelle utilizzati per questo tipo di esperienze. Inoltre, grazie da un lato all’integrazione delle strutture di test nel System on Chip da caratterizzare e, dall’altro, ad una strategia d’interfaccia che si basa sia sul JTAG che sui Wrappers, i test possono essere eseguiti ad alta frequenza usando però solamente connessioni lente fra un PC e il dispositivo da testare, diminuendo così drasticamente il costo globale degli esperimenti.
Questa tesi mostra e discute i risultati ottenuti da molte campagne di esperimenti di radiazione su un System on Chip costruito in tecnologia CMOS a 90 nm da STMicroelectronics. Tale dispositivo è stato pensato e realizzato per essere parte di un complesso progetto automotive; ci siamo dunque focalizzati sulle problematiche derivanti dall’impatto che la radiazione terrestre può avere in questo dispositivo. Abbiamo quindi esposto il chip sia a flussi di neutroni che di particelle alfa. Grazie ai dati ottenuti dagli esperimenti, abbiamo calcolato la sensibilità del modulo SRAM sia a particelle alfa che a neutroni, e abbiamo scoperto che quest’ultima è decisamente inferiore della prima. Abbiamo quindi caratterizzato il comportamento del microprocessore quando è esposto a particelle alfa. Il test statico ha dimostrato che i flip-flop che costituiscono i registri interni del microprocessore hanno un tasso di errore indotto da radiazione più elevato rispetto al modulo memoria utente e memoria codice. Questo risultato è di grande importanza e deve essere considerato, per esempio, quando si costruisce una piattaforma di fault-injection. Per effettuare il test dinamico del microprocessore abbiamo costruito due diversi codici di riferimento, in modo da capire come la corruzione delle riverse risorse di memorizzazione influenzi l’esecuzione del codice. I risultati ottenuti dimostrano che, in una tipica applicazione, gli errori nella memoria codice sono decisamente predominanti rispetto a quelli nei registri interni. Inoltre abbiamo visto che i bit di memoria codice e dei registri non sono sempre critici, e la loro corruzione non necessariamente si propaga all’uscita. Infine, abbiamo considerato l’efficacia e i costi di diverse tecniche di irrobustimento. In particolare, abbiamo studiato come l’ottimizzazione del layout proposta del Design For Manufacturing o la Triple Module Redundancy influenzino la sensibilità alla radiazione del microprocessore. Abbiamo considerato dei chip costruiti con diversi livelli di maturità del Design For Manufacturing e i risultati sperimentali dimostrano che un più alto livello di ottimizzazione aumenta la resistenza del dispositivo alla radiazione alfa. Le tecniche di irrobustimento, comunque, hanno un costo. La decisione su quale tecnica adottare quando si costruisce un dispositivo complesso è un trade-off fra costi, performance e, ovviamente, affidabilità. Le strategie da adottare per un particolare prodotto dipendono quindi dai suoi requisiti e dall’ambiente in cui dovrà essere impiegato
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Recent Trends and Perspectives on Defect-Oriented Testing
No full textElectronics employed in modern safety-critical systems require severe qualification during the manufacturing process and in the field, to prevent fault effects from manifesting themselves as critical failures during mission operations. Traditional fault models are not sufficient anymore to guarantee the required quality levels for chips utilized in mission-critical applications. The research community and industry have been investigating new test approaches such as device-aware test, cell-aware test, path-delay test, and even test methodologies based on the analysis of manufacturing data to move the scope from OPPM to OPPB. This special session presents four contributions, from academic researchers and industry professionals, to enable better chip quality. We present results on various activities towards this objective, including device-aware test, software-based self-test, and memory test.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Quantum & Computer EngineeringComputer Engineerin
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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