112,913 research outputs found
Renormalized Equations in Turbulent Immiscible Gas-Liquid Flows—The Target on LES-Formulation
No full textInternational audienceBook coverBook coverTurbulent Cascades II pp 37–43Cite asRenormalized Equations in Turbulent Immiscible Gas-Liquid Flows—The Target on LES-Formulation M. A. Gorokhovski & V. L. Saveliev Conference paper First Online: 21 May 2019 415 AccessesPart of the ERCOFTAC Series book series (ERCO,volume 26)AbstractIn the group-theoretical model of stationary homogeneous turbulence (PRE 72, 016302, 2005), the renormalized form of the Navier-Stokes equations includes the turbulent viscosity, which appears not from averaging of the nonlinear term, but from the molecular viscosity term. The next raised question is as follows. In the immiscible gas-liquid turbulent flow, the motion equation is completed by the surface tension force, acting on the interface. When such a flow is averaged over some length-scale, there is no more interfaces. Then at the high Reynolds number, what is the renormalized form of governing equations in this flow? In the framework of approach of the aforementioned paper, the result is this: similar to the Smagorinsky viscosity, the “effective surface tension coefficient” appears in the invariant to scaling transformation form. Its expression is discussed in this paper
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Automated mapping using multilevel B-Splines
No full textThis paper describes application of multilevel B-Splines approximation (MBA) algorithm to the SIC2004 exercise as a high performance automatic mapping means in emergency situations. MBA method was compared with kriging, and various flexible MBA method's tuning "controls" were proposed and discussed. Outliers automatic detection and delineation techniques considered could be used to process outliers without the loss in performance. Prior data were used to adjust method parameters and discover the pattern of spatial correlation. The interpolation algorithm development did not assume any information about the phenomena in addition to values given. © 2005 Anatoly A. Saveliev, Andrey V. Romanov, and Svetlana S. Mukharamova
Automated mapping using multilevel B-Splines
No full textThis paper describes application of multilevel B-Splines approximation (MBA) algorithm to the SIC2004 exercise as a high performance automatic mapping means in emergency situations. MBA method was compared with kriging, and various flexible MBA method's tuning "controls" were proposed and discussed. Outliers automatic detection and delineation techniques considered could be used to process outliers without the loss in performance. Prior data were used to adjust method parameters and discover the pattern of spatial correlation. The interpolation algorithm development did not assume any information about the phenomena in addition to values given. © 2005 Anatoly A. Saveliev, Andrey V. Romanov, and Svetlana S. Mukharamova
First results of scintillator readout with silicon photomultiplier
No full textA new type of silicon device has been realized that has many properties, comparable to, or better than, a conventional PMT (Photomultiplier Tube). This paper presents the first results of using these photodetectors in place of a PMT in the readout of scintillators for possible PET (Positron Emission Tomography) applications. This device, the Silicon Photomultiplier (SiPM), is effectively an avalanche photodiode operated in Geiger mode. In Geiger-mode detectors, a very large current signal is produced regardless of the size of the input, giving just logical rather than proportional information. However, the SiPM is subdivided into a large number (1440) A microcells that act as independent and virtually identical Geiger-mode photodiodes. The outputs of all these individual microcells are connected so that the total output signal is the sum of the signals from all of the microcells that were activated. In this way proportional information can be obtained. As a consequence of their design, these detectors have potentially very fast timing, high gain (10(5) - 10(6)) at low bias voltage (similar to 50 V), a high quantum efficiency (35% at 500 nm), excellent single photoelectron resolution and are cheap to manufacture. Here we present results obtained with this new photodetector when used with pulsed LED and scintillator pixels
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
A fossil brain from the Cretaceous of European Russia and avian sensory evolution
No full textFossils preserving traces of soft anatomy are rare in the fossil record; even rarer is evidence bearing on the size and shape of sense organs that provide us with insights into mode of life. Here, we describe unique fossil preservation of an avian brain from the Volgograd region of European Russia. The brain of this Melovatka bird is similar in shape and morphology to those of known fossil ornithurines (the lineage that includes living birds), such as the marine diving birds Hesperornis and Enaliornis, but documents a new stage in avian sensory evolution: acute nocturnal vision coupled with well-developed hearing and smell, developed by the Late Cretaceous (ca 90?Myr ago). This fossil also provides insights into previous ‘bird-like’ brain reconstructions for the most basal avian Archaeopteryx—reduction of olfactory lobes (sense of smell) and enlargement of the hindbrain (cerebellum) occurred subsequent to Archaeopteryx in avian evolution, closer to the ornithurine lineage that comprises living birds. The Melovatka bird also suggests that brain enlargement in early avians was not correlated with the evolution of powered fligh
Variations on the Author
No full text“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
The Silicon Photomultiplier for application to high-resolution Positron Emission Tomography
No full textPositron Emission Tomography (PET) for small animal studies requires high-resolution gamma cameras with high sensitivity. Traditionally, inorganic scintillators are used and, in recent times, coupled to position sensitive PMTS to achieve a higher resolution. Such PSPMTs are costly, operated at high voltage and have a relatively low packing fraction. However, their advantage, compared to current solid state photodetectors, is their high signal-to-noise ratio. The Silicon Photomultiplier (SiPM) is a silicon diode detector that shows great promise as a photodetector for scintillators and hence application in nuclear medicine imaging applications. The microcell MRS (Metal-Resistor-Semiconductor) structure of the SiPM leads to a self-quenching, Geiger-mode avalanche photodiode (GAPD), that produces a large gain (5 x 105) at low bias voltage (50 V) and proportional output for moderate photon flux. Such a compact silicon detector, with a performance similar to a PMT, is obviously well disposed to being developed into a close-packed array in order to have a position-sensitive detection surface. We propose a miniature, high-resolution camera for a small-animal PET imaging system that is based on such an array of SiPM. The design is based upon the classic Anger camera principle; each detector module consists of a continuous slab of scintillator, viewed by a matrix of SiPM. A detector head of 4 x 4 cm(2) in area is proposed, constructed from three such modules of the continuous camera described above. The stacked layers would give the system intrinsic depth of interaction (DOI) information. A summary of measured SiPM performance and results of a simulation of the proposed camera, using the Monte Carlo package GEANT4, are presented. It is shown that using three layers of 5 mm thick LSO, gives an efficiency of 68% with maximum count rates in the front layers. Intrinsic spatial resolution of < 0.4mm FWHM was found although this is degraded at the edges. Although the inclusion of DOI information increases the overall spatial resolution, the parallax error was still found to be the limiting factor in a small animal system. (c) 2006 Elsevier B.V. All rights reserved
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