44,857 research outputs found
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Impact of lignin/zinc phosphinate introduced by melt spinning on the fire retardant properties of bio-source textile structure
No full textLignin has the advantage of being bio-based compound, can be effectively used as charring agent with other flame retardant additives. Formulations based on combination of various lignin types and zinc phosphinate were studied in PA11 previously [1]. This work is dedicated to the flame behavior characterization of textile fabrics obtained from those formulations. Different PA11 composites based on lignin and zinc phosphinate are formulated and extruded. The melt spinning process was used to produce multifilament from these various PA11 / lignin / zinc phosphinate. Physical and mechanical characterizations were carried out on the different multifilament. These yarns were knitted in order to obtain fabrics. Pyrolysis Combustion Flow Calorimeter and Mass Loss Calorimeter were performed on the formulations in order to study the fire behavior
Prime values of and , quadratic
Get PDFWe prove an asymptotic formula for primes of the shape with integers and of the shape with prime. Here is a binary quadratic form with integer coefficients, irreducible over and has no local obstructions. This refines the seminal work of Friedlander and Iwaniec on primes of the form and Heath-Brown and Li on primes of the form , as well as earlier work of the author with Lam and Schindler on primes of the form with a positive definite form.45 page
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Prototype system for supporting the incremental modelling of vague geometric configurations
No full textIn this paper the need for Intelligent Computer Aided Design (Int.CAD) to jointly support design and learning assistance is introduced. The paper focuses on presenting and exploring the possibility of realizing learning assistance in Int.CAD by introducing a new concept called Shared Learning. Shared Learning is proposed to empower CAD tools with more useful learning capabilities than that currently available and thereby provide a stronger interaction of learning between a designer and a computer. Controlled computational learning is proposed as a means whereby the Shared Learning concept can be realized. The viability of this new concept is explored by using a system called PERSPECT. PERSPECT is a preliminary numerical design tool aimed at supporting the effective utilization of numerical experiential knowledge in design. After a detailed discussion of PERSPECT's numerical design support, the paper presents the results of an evaluation that focuses on PERSPECT's implementation of controlled computational learning and ability to support a designer's need to learn. The paper then discusses PERSPECT's potential as a tool for supporting the Shared Learning concept by explaining how a designer and PERSPECT can jointly learn. There is still much work to be done before the full potential of Shared Learning can be realized. However, the authors do believe that the concept of Shared Learning may hold the key to truly empowering learning in Int.CAD
Deux images xylographiques de Guan yin.
No full textGui yi jun 歸 義 軍. Gui yi jun jie du shi 歸 義 軍 節 度 使. Da ci da bei jiu ku Guan shi yin pu sa 大 慈 大 悲 救 苦 觀 世 音 菩 薩. tai fu 太 傅. Cao Yuan zhong 曹 元 忠. jie du shi 節 度 使. Textes et images imprimésNumérisation effectuée à partir d'un document original.Texte du cartouche de gauche : Da ci da bei jiu ku Guan shi yin pu sa 大 慈 大 悲 救 苦 觀 世 音 菩 薩. Gravure exécutée, zao 造, par Cao Yuan zhong 曹 元 忠, jie du shi du Gui yi jun, faisant fonction de tai fu 歸 義 軍 節 度 使 檢 校 太 傅, selon le cartouche de droite. Encadrement : 20,5 × 13,3 cm. Encre noire. Chacune des 2 images est disposée au milieu d'une f. Pour d'autres images similaires, cf. les Pelliot chinois 4514.6 (1-4) et S. printed 9, ainsi que les fragments du British Museum 242, 244 et 241 (ce dernier actuellement au Royal Ontario Museum). Voir en outre l'exemplaire rehaussé de couleurs conservé au Musée Guimet, E.O. 1218 D. Certaines de ces xylographies comportent un texte, daté de 947, disposé au-dessous de l'image, le texte et l'image provenant d'une gravure unique. Sur ce n°, les textes manquent, par déchirure. Cf. Kikutake Jun'ichi, in BG , 101 (1975), p. 6 ; cf. également M.-R. Séguy, in CETH-1 , p. 123
K. F. C. Rose, The Date and Author of the Satyricon. With an Introduction by J. P. Sullivan
No full textVerdière Raoul. K. F. C. Rose, The Date and Author of the Satyricon. With an Introduction by J. P. Sullivan. In: L'antiquité classique, Tome 42, fasc. 1, 1973. pp. 279-280
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