910 research outputs found
Mass and stiffness modifications to achieve desired natural frequencies
No full textDmitri D. Sivan and Yitshak M. Ra
Quantitative performance modeling of scientific computations and creating locality in numerical algorithms
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 141-150) and index.by Sivan Avraham Toledo.Ph.D
Poétique d' "économie textuelle"
No full textCette étude propose une lecture de quelques essais critiques de Jacques Sivan autour de Francis Ponge, Denis Roche, Charles Olson et Ezra Pound. D'une part on montre comment, à travers des outils critiques librement empruntés à Gilles Deleuze (molécule, machine, agencement, devenir, plan d'immanence, littérature mineure...), Sivan construit aussi bien un discours réflexif qu'une véritable poétique. D'autre part on tente d'esquisser les contours de cette poétique, centrée sur la notion d'économie textuelle, qu'il faut entendre comme ancrage du travail poétique sur les transactions du quotidien et, en dernière analyse, comme une forme renouvelée d'engagement
Comparing learning curves of experts and novices: A novel approach to the study of simulator effectiveness and fidelity.
No full textWe describe a new approach to the study of simulator fidelity and training efficiency. It is based on comparing learning curves of novice trainees and domain experts in a simulator. The major claim is that if a simulator represents a relevant environment for the training of the operational task, domain experts performanceshould show a major advantage over novice trainees. Two measures of domain expert performance are important in the evaluation of the simulator. One is the distance (in training hours or sessions) between performance levels of novices anddomain experts. It reflects the difficulty of the measured ability and the predicted amount of training required by novices to reach expert levels. A second measure, which represents simulator fidelity, is the distance between expert performance and performance asymptote in the simulator. The approach has been successfully applied in the study of a desktop, partial task flight simulator
Liquid metal enabled pump
No full textSmall-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics.Shi-Yang Tang, Khashayar Khoshmanesh, Vijay Sivan, Phred Petersen, Anthony P. OMullane,d, Derek Abbott, Arnan Mitchell, and Kourosh Kalantar-zade
Design and structural modifications of vibratory systems to achieve prescribed modal spectra / Dmitri D. Sivan.
No full textBibliography: leaves 184-192.xii, 198 leaves : ill. ; 30 cm.This thesis reports on problems associated with design and structural modification of vibratory systems. Several common problems encountered in practical engineering applications are described and novel strategies for solving this problems are proposed. Mathematical formulations of these problems are generated, and solution methods are developed.Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 199
Essays on social norms
No full textThesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, 2018.Cataloged from PDF version of thesis.Includes bibliographical references.The first essay addresses why people might conform to norms that they do not endorse. One explanation is pluralistic ignorance: when everyone appears to endorse a norm, even nonendorsers will conform so as to feign their commitment to the group's values, thereby exacerbating the misperception. But this explanation is limited because people seem to even conform to norms that are widely known to contradict the group's values ("visibly unpopular norms"), to the point that their conformity appears insincere. I argue that such insincere conformity is an especially potent signal of commitment because it shows that one is willing to sacrifice one's personal preferences on others' behalf. Using both qualitative and experimental methods, I study the visibly unpopular norm prescribing excessive drinking in after-hour business gatherings in South Korea. The analysis indicates that an insincere conformist to the drinking norm is perceived as an especially committed relationship partner. An important implication is that some norms might persist not despite the fact they contradict group members' preferences but because of this contradiction. The second essay (coauthored with Ezra W. Zuckerman Sivan) addresses why norms might not persist despite their wide popularity. Recent research suggests that many norms may be upheld by closet deviants who engage in enforcement so as to hide their deviance. But various empirical accounts indicate that audiences are often quite sensitive to this ulterior motive. Our theory and experimental evidence identify when inferences of ulterior motive are drawn and clarify the implications of such inferences. Our main test pivots on two contextual factors: (1) the extent to which individuals might try to strategically feign commitment and (2) the contrast between "mandated" enforcement, where individuals are asked for their opinions of deviance, and "entrepreneurial" enforcement, where enforcement requires initiative to interrupt the flow of social interaction. When the context is one where individuals might have a strategic motive and enforcement requires entrepreneurial initiative, suspicions are aroused because the enforcers could have remained silent and enjoyed plausible deniability that they had witnessed the deviance or recognized its significance. Given that the mandate for enforcement might be rare, a key implication is that norms might frequently be under-enforced.by Minjae Kim.Chapter 1. A Man Is Known by His Cup: Signaling Commitment via Insincere Conformity -- Chapter 2. Faking It Is Hard to Do: Entrepreneurial Norm Enforcement and Suspicions of Deviance (coauthored with Ezra W. Zuckerman Sivan).Ph. D
Evidence for centennial scale sea level variability during the Medieval Climate Optimum (Crusader Period) in Israel, eastern Mediterranean
No full textThe current study provides evidence supporting a sea-level drop of up to about 50 ± 20 cm at the eastern coasts of the Mediterranean basin during the period AD 900–1300. The estimate is based on a variety of archaeological remains, mostly from the Crusader period, compared with other archaeological and biological proxies of sea level from the periods before and after.The Crusader low levels overlap the period known as the ‘Medieval Warm Period’ (MWP) or the ‘Medieval Climate Anomaly’ (MCA). On the basis of published data it appears that a positive North Atlantic Oscillation (NAO) phase coincided with a negative Southern Oscillation Index (SOI), the former affecting the temperature and freshwater flux in the Mediterranean Sea and most of its rivers, and the latter affecting the Nile outflow. Changes of 0.125 psu in salinity and 0.4 °C are estimated as upper limits for the change, and these are expected to cause a sea-level drop consistent in magnitude with the observed values. These provide the upper limit for a regional climate-forcing attribution of the observed sea level low. The possibility of crustal uplifts contributing to the observed changes is also discussed
Paleo-Urban Development and Late Quaternary Environmental Change in the Akko Area
No full textHolocene sea level changes as well as regional and local tectonic movements determined the configuration of the Mediterranean coast of northern Israel. This, in turn, influenced the location and type of settlements, in particular of Akko. The paleoenvironment and paleogeography of Akko bay are tentatively reconstructed here through the study of the stratigraphy and nature of the deposits.Des changements de niveau à l'holocène aussi bien que des mouvements régionaux et locaux déterminèrent la configuration de la côte nord d'Israël. Ces modifications influencèrent à leur tour l'emplacement et le type des établissements, en particulier d'Akko. Un essai de reconstruction du paléoenvironnement et de la paléogéographie est tenté ici à travers l'étude de la stratigraphie et de la nature des dépôts.Inbar Moshe, Sivan Dorit. Paleo-Urban Development and Late Quaternary Environmental Change in the Akko Area. In: Paléorient, 1983, vol. 9, n°2. pp. 85-91
Parental math engagement with preterm and full-term toddlers
No full textSeveral studies suggest that children born prematurely disproportionately struggle in math later in life. Additionally, as early math skills at the start of school are strong predictors of later math and reading, a growing body of literature has examined how parental practices that support young children's learning of number concepts at home. This is referred to as the home numeracy environment. In this study, we explore differences in the home numeracy environment by comparing preterm and full-term toddlers. Additionally, we explore how birth status affects counting skills. A sample of 20 2-year-old toddlers and their parents completed a picture description task to assess the frequency of parents’ number talk with their children, a counting task for children, and a home numeracy questionnaire for parents. Interestingly, parents of preterm children used more number talk than parents of full-term children; however, parents of preterm children also reported participating in significantly fewer home math activities. Limited evidence of a significant difference between birth status (preterm or full-term) and child's counting skills was found. Overall, these findings illuminate the need to differentiate between different aspects of the home numeracy environment (namely, parental number talk and home math activities) and provide opportunities for future expansion involving answering questions about how parental beliefs about their child's ability may affect the type of engagement children receive
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