3,974,762 research outputs found
Los Angeles-Leningrad sister cities hearing; Footage from Perm 35 Camp; Interview with Si Frumkin regarding the death of Andrei Sakharov, 1989
No full textSister cities hearing includes statements by Si Frumkin and Zev Yaroslavsky.Digital recordingDigital finding aid
Addio vecchio SI ...
No full textIl Système International d'unités, abbreviato con SI, regola dal 1960 il complesso delle unità di misura. Esso ha subito numerose modifiche nel corso della sua storia, per inseguire l’evoluzione delle scoperte nella fisica e approfittare dei trovati nella tecnologia. Il SI è governato dalla Convenzione del Metro, un trattato intergovernativo firmato a Parigi nel 1875 da 17 Paesi, e ora esteso a ben 55. Tale Convenzione è governata dalla CGPM (Conférence Générale des Poids et Mesures): ogni quattro anni (mediamente) essa convoca i rappresentanti dei governi degli Stati membri per prendere le decisioni più importanti relative alla Convenzione e al SI. Dal punto di vista tecnico, le decisioni, sotto forma di risoluzioni, sono prese sulla base delle proposte formulate dal CIPM (Comité International des Poids et Mesures, formato da esperti riconosciuti internazionalmente) con il sostegno operativo del BIPM (Bureau International des Poids et Mesures, struttura permanente delle Convenzione con sede e Sèvres, vicino a Parigi).
Dal 17 al 21 ottobre scorsi s’è svolta presso il BIPM la 24a riunione della CGPM. Fra le altre decisione prese, ve n’è una storica: il SI come lo conosciamo oggi va in pensione, sostituito da uno tutto appoggiato sull’uso delle costanti fisiche universali. O meglio, pensione e sostituzione avranno luogo dalla prossima riunione della CGPM (la 25a nel 2014), dopo aver verificato che tutti i requisiti tecnici siano stati soddisfatti pienamente; ma la linea è ormai tracciata
Helium irradiation effects in polycrystalline Si, silica, and single crystal Si
Full text linkTransmission electron microscopy (TEM) has been used to investigate the effects of room temperature 6 keV helium ion irradiation of a thin (≈55 nm thick) tri-layer consisting of polycrystalline Si, silica, and single-crystal Si. The ion irradiation was carried out in situ within the TEM under conditions where approximately 24% of the incident ions came to rest in the specimen. This paper reports on the comparative development of irradiation-induced defects (primarily helium bubbles) in the polycrystalline Si and single-crystal Si under ion irradiation and provides direct measurement of a radiation-induced increase in the width of the polycrystalline layer and shrinkage of the silica layer. Analysis using TEM and electron energy-loss spectroscopy has led to the hypothesis that these result from helium-bubble-induced swelling of the silicon and radiation-induced viscoelastic flow processes in the silica under the influence of stresses applied by the swollen Si layers. The silicon and silica layers are sputtered as a result of the helium ion irradiation; however, this is estimated to be a relatively minor effect with swelling and stress-related viscoelastic flow being the dominant mechanisms of dimensional change
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
Evidence for Coupling of Si-Si Lattice Vibration and Si-D Wagging Vibration in Deuterated Amorphous Silicon
No full textBai nian si suo
No full textBen shu shi zuo zhe de yi bu sui bi, za wen ji. nei rong bao gua : bai nian si suo, shi ren gang zou, ma shang hui lai, zun zhong shui de wen hua cha yi, yi ben shu de bei hou, shang hai de yi ri, shui bo duo le zhong guo ren sheng qi de quan li, liang li cao mei de hui xuan den
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
New approaches to casting hypereutectic Al-Si alloys to achieve simultaneous refinement of primary silicon and modification of eutectic silicon
Full text linkThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityHypereutectic Al-Si alloys are of increasing interest for applications that require a combination of light weight and high wear resistance, such as pistons, liner-less engine blocks and pumps. The wear resistance of this class of alloys is due to the presence of hard primary Si particles formed during casting. The objective of this work was to develop one or more methods of refining primary silicon in cast hypereutectic Al-Si alloys to compete with the conventional process of adding phosphorous and to achieve the simultaneous modification of silicon in the Al-Si eutectic. A robust sampling/casting technique was developed to minimise macro-segregation of primary silicon during solidification of hypereutectic Al-Si alloys by using water cooled steel mould with cooling rate in excess of 15 K/s. The morphology of silicon phases was found to change with increasing melt temperature and cooling rate. The high cooling rate and superheat temperature produces a good distribution of polyhedral primary silicon particles in a refined lamellar eutectic matrix in solidification of commercial purity Al-Si alloys. Removing Ca by fluxing with K2SiF6 prior to casting can improve the refinement and modification effect of Mg and Sb respectively. Effects of various inoculants were studied. Microstructural analysis showed that Mg and ZnS refined primary Si whereas MgO, CaO and Na2S coarsened the primary Si together with a modification effect on the eutectic Si. Adding Zn had no effect on morphology of Si phases. Refinement of both primary and eutectic silicon phases was observed for the Al-15Si alloy with Mg content ≤ 0.3 wt%.
P-doped γ-Al2O3 was found to be a potent substrate to nucleate primary silicon whilst good modification of the eutectic matrix is retained during solidification of hypereutectic Al-Si alloys. On using P-doped γ-Al2O3 could be a perfect and clean source of P without additional impurities.
A new solid-liquid duplex casting process was devised to achieve simultaneous refinement and modification of Si phases in hypereutectic Al-Si alloys with improvement in mechanical properties. The static mechanical properties of Al-Si produced by the solid-liquid duplex casting process are significantly better than conventionally cast untreated Al-Si and slightly better than conventionally cast Al-Si treated with P and/or Sr. A novel Al-ZnS master alloy was developed by in situ reaction of Zn and Na2S in the Al melt. The results from this study leave little doubt that this novel Al-ZnS master alloy is a promising refiner in solidification of hypereutectic Al-Si alloys. It refines primary silicon to the same extent as that achieved by adding P via Cu-P following the same refinement mechanism.EPSRC,U
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
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