54,748 research outputs found
Direct numerical simulation of 'short' laminar separation bubbles with turbulent reattachment
Full text linkDirect numerical simulation of the incompressible Navier–Stokes equations is used to study flows where laminar boundary-layer separation is followed by turbulent reattachment forming a closed region known as a laminar separation bubble. In the simulations a laminar boundary layer is forced to separate by the action of a suction profile applied as the upper boundary condition. The separated shear layer undergoes transition via oblique modes and [Lambda]-vortex-induced breakdown and reattaches as turbulent flow, slowly recovering to an equilibrium turbulent boundary layer. Compared with classical experiments the computed bubbles may be classified as ‘short’, as the external potential flow is only affected in the immediate vicinity of the bubble. Near reattachment budgets of turbulence kinetic energy are dominated by turbulence events away from the wall. Characteristics of near-wall turbulence only develop several bubble lengths downstream of reattachment. Comparisons are made with two-dimensional simulations which fail to capture many of the detailed features of the full three-dimensional simulations. Stability characteristics of mean flow profiles are computed in the separated flow region for a family of velocity profiles generated using simulation data. Absolute instability is shown to require reverse flows of the order of 15–20%. The three-dimensional bubbles with turbulent reattachment have maximum reverse flows of less than 8% and it is concluded that for these bubbles the basic instability is convective in nature
Ultra-broadband wavelength conversion based on four-wave mixing in a Raman DFB fiber laser
No full textWe report highly efficient four-wave mixing (FWM) within a 30cm-long centre pi phase-shifted Raman DFB fiber laser with a continuous frequency tuning range of ~19.9 THz with the FWM conversion efficiency up to -25dB
Minda lestari dalam pengurusan alam sekitar berteraskan maqasid syariah
Full text linkIsu-isu berkaitan pencemaran alam sekitar terus diperkatakan dari semasa ke semasa. Terbaharu ialah perbuatan melepas dan melupus bahan buangan mengandungi bahan berbahaya ke Sungai Gong yang menyebabkan gangguan bekalan air kepada kira-kira lima juta pengguna di sekitar Lembah Klang
Shape studies of quark jets versus gluon jets at s=10 GeV
No full textcomplete author list:
Alam M.; Kim I.; Nemati B.; O'Neill J.; Romero V.; Severini H.; Sun C.; Wang P.; Zoeller M.; Crawford G.; Fulton R.; Gan K.; Kagan H.; Kass R.; Lee J.; Malchow R.; Morrow F.; Sung M.; White C.; Whitmore J.; Wilson P.; Butler F.; Fu X.; Kalbfleisch G.; Lambrecht M.; Skubic P.; Snow J.; Wang P.; Bortoletto D.; Brown D.; Dominick J.; McIlwain R.; Miao T.; Miller D.; Modesitt M.; Schaffner S.; Shibata E.; Shipsey I.; Battle M.; Ernst J.; Kroha H.; Roberts S.; Sparks K.; Thorndike E.; Wang C.; Artuso M.; Goldberg M.; Haupt T.; Horwitz N.; Kennett R.; Moneti G.; Playfer S.; Rozen Y.; Rubin P.; Skwarnicki T.; Stone S.; Thulasidas M.; Yao W.; Zhu G.; Stroynowski R.; Barnes A.; Bartelt J.; Csorna S.; Egyed Z.; Jain V.; Letson T.; Mestayer M.; Sheldon P.; Akerib D.; Barish B.; Chadha M.; Cowen D.; Eigen G.; Miller J.; Urheim J.; Weinstein A.; Menary S.; Morrison R.; Nelson H.; Richman J.; Tajima H.; Schmidt D.; Sperka D.; Witherell M.; Acosta D.; Masek G.; Ong B.; Paar H.; Sivertz M.; Procario M.; Daoudi M.; Ford W.; Johnson D.; Lingel K.; Lohner M.; Rankin P.; Smith J.; Alexander J.; Bebek C.; Berkelman K.; Besson D.; Browder T.; Cassel D.; Cheu E.; Coffman D.; Drell P.; Ehrlich R.; Garcia-Sciveres M.; Geiser B.; Gittelman B.; Gray S.; Hartill D.; Heltsley B.; Honscheid K.; Jones C.; Kandaswamy J.; Katayama N.; Kim P.; Kreinick D.; Ludwig G.; Masui J.; Mevissen J.; Mistry N.; Nandi S.; Ng C.; Nordberg E.; O'Grady C.; Patterson J.; Peterson D.; Riley D.; Sapper M.; Selen M.; Worden H.; Worris M.; Würthwein F.; Avery P.; Freyberger A.; Rodriguez J.; Stephens R.; Yelton J.; Henderson S.; Kinoshita K.; Liu T.; Saulnier M.; Wilson R.; Yamamoto H.; Sadoff A.; Ammar R.; Ball S.; Baringer P.; Coppage D.; Davis R.; Hancock N.; Kelly M.; Kwak N.; Lam H.; Ro S.; Kubota Y.; Lattery M.; Nelson J.; Perticone D.; Poling R.; Schrenk S.; Wang R.; Wang R.; Poling R.; Schrenk S.; Nelson J.; Perticone D.; Alam M.S
1.06 µm picosecond pulsed, normal dispersion pumping for generating efficient broadband infrared supercontinuum in meter-length single-mode tellurite holey fiber with high Raman gain coefficient
No full textWe investigate efficient broadband infrared supercontinuum generation in meter-length single-mode small-core tellurite holey fiber. The fiber is pumped by 1.06µm picosecond pulses in the normal dispersion region. The high Raman gain coefficient and the broad Raman gain bands of the tellurite glass are exploited to generate a cascade of Raman Stokes orders, which initiate in the highly normal dispersion region and quickly extend to longer wavelengths across the zero dispersion wavelength with increasing pump power. A broadband supercontinuum from 1.06µm to beyond 1.70µm is generated. The effects of the pump power and of the fiber length on the spectrum and on the power conversion efficiency from the pump to the supercontinuum are discussed. Power scaling indicates that using this viable normal dispersion pumping scheme, 9.5 W average output power of infrared supercontinuum and more than 60% conversion efficiency can be obtained from a 1 m long tellurite fiber with a large mode area of 500µm2
Synthesis, characterization and bio-activity of a bidentate NS Schiff base of S-allyldithiocarbazate and its divalent metal complexes: X-ray crystal structures of the free ligand and its nickel(II) complex
No full textTransition metal complexes ML2 (2–6) [where
M = Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and HL = allyl-2-
(4-benzyloxyphenylmethylene)hydrazine carbodithioate (1)]
have been prepared by the reaction of the ligand with metal
ions in 2:1 molar ratio and characterized by physicochemical
techniques and spectroscopic methods. The crystal
structures of the free ligand and its nickel(II) complex 2 have
been determined by X-ray diffractometry. The ligand exists
in its thione tautomeric form both in solution and in the solid
state. In complex 2, square-planar coordination of nickel(II)
was achieved by two chelating ligand moieties coordinating
through the azomethine nitrogen and the deprotonated thione
sulphur atom. Based on the crystal structures of analogous
dithiocarbazate species, a square-planar geometry was assumed for the copper(II) and palladium(II) complexes,
and a tetrahedral coordination sphere for the zinc(II) and
cadmium(II) derivatives. The in vitro bactericidal activity
suggests that the palladium(II) complex is strongly active
against two bacteria. The cadmium(II) complex is moderately
cytotoxic with an LC50 value of 409 lg/ml, but less
active than gallic acid, LC50 = 78 lg/ml
Settling of finite-size particles in isotropically forced, homogeneous turbulence: interface-resolved simulations
No full textWe have simulated the gravity-induced settling of finite-size particles in a turbulent background flow which is forced in a statistically-stationary fashion. The simulations are accurately resolving the solid-fluid interface with the aid of an immersed boundary technique [1]. The parameters of the simulation are (apart from background turbulence) identical to those of reference [2], where particle clustering was observed at a Galileo number of 178 and a solid volume fraction of 0.005. In the present case, it is found that a relative turbulence intensity of 0.24 leads to the disappearance of the clusters; as a consequence, the increase in average particle settling velocity found in [2] also vanishes. [1] M. Uhlmann. An immersed boundary method with direct forcing for the simulation of particulate flows. J. Comput. Phys., 209(2):448–476, 2005. [2] M. Uhlmann and T. Doychev. Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion. J. Fluid Mech., 752:310–348, 2014
Measurement of the ratio scrB(D+→π0l+ν)/ scrB(D+→K̄0l+ν)
No full textcomplete author list:
Alam M.; Kim I.; Nemati B.; O'Neill J.; Severini H.; Sun C.; Zoeller M.; Crawford G.; Daubenmier C.; Fulton R.; Fujino D.; Gan K.; Honscheid K.; Kagan H.; Kass R.; Lee J.; Malchow R.; Morrow F.; Skovpen Y.; Sung M.; White C.; Whitmore J.; Wilson P.; Butler F.; Fu X.; Kalbfleisch G.; Lambrecht M.; Ross W.; Skubic P.; Snow J.; Wang P.; Wood M.; Bortoletto D.; Brown D.; Fast J.; McIlwain R.; Miao T.; Miller D.; Modesitt M.; Schaffner S.; Shibata E.; Shipsey I.; Wang P.; Battle M.; Ernst J.; Kroha H.; Roberts S.; Sparks K.; Thorndike E.; Wang C.; Dominick J.; Sanghera S.; Skwarnicki T.; Stroynowski R.; Artuso M.; He D.; Goldberg M.; Horwitz N.; Kennett R.; Moneti G.; Muheim F.; Mukhin Y.; Playfer S.; Rozen Y.; Stone S.; Thulasidas M.; Vasseur G.; Zhu G.; Bartelt J.; Csorna S.; Egyed Z.; Jain V.; Sheldon P.; Akerib D.; Barish B.; Chadha M.; Chan S.; Cowen D.; Eigen G.; Miller J.; O'Grady C.; Urheim J.; Weinstein A.; Acosta D.; Athanas M.; Masek G.; Ong B.; Paar H.; Sivertz M.; Bean A.; Gronberg J.; Kutschke R.; Menary S.; Morrison R.; Nakanishi S.; Nelson H.; Nelson T.; Richman J.; Ryd A.; Tajima H.; Schmidt D.; Sperka D.; Witherell M.; Procario M.; Yang S.; Balest R.; Cho K.; Daoudi M.; Ford W.; Johnson D.; Lingel K.; Lohner M.; Rankin P.; Smith J.; Alexander J.; Bebek C.; Berkelman K.; Besson D.; Browder T.; Cassel D.; Cho H.; Coffman D.; Drell P.; Ehrlich R.; Garcia-Sciveres M.; Geiser B.; Gittelman B.; Gray S.; Hartill D.; Heltsley B.; Jones C.; Jones S.; Kandaswamy J.; Katayama N.; Kim P.; Kreinick D.; Ludwig G.; Masui J.; Mevissen J.; Mistry N.; Ng C.; Nordberg E.; Ogg M.; Patterson J.; Peterson D.; Riley D.; Salman S.; Sapper M.; Worden H.; Würthwein F.; Avery P.; Freyberger A.; Rodriguez J.; Stephens R.; Yelton J.; Cinabro D.; Henderson S.; Kinoshita K.; Liu T.; Saulnier M.; Shen F.; Wilson R.; Yamamoto H.; Selen M.; Sadoff A.; Ammar R.; Ball S.; Baringer P.; Coppage D.; Copty N.; Davis R.; Hancock N.; Kelly M.; Kwak N.; Lam H.; Kubota Y.; Lattery M.; Nelson J.; Patton S.; Perticone D.; Poling R.; Savinov V.; Schrenk S.; Wang R.; Alam M.; Savinov V.; Poling R.; Wang R.; Schrenk S.; Nelson J.; Lattery M.; Perticone D.; Patton S.; Kwak N.; Kelly M.; Kubota Y.; Lam H.; Hancock N.; Alam M.S
Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw
No full textMesophilic-hydrothermal (80-160 degrees C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 degrees C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. (C) 2015 Elsevier Ltd. All rights reserved
Recommendation domains for pond aquaculture: country case study: development and status of freshwater aquaculture in Bangladesh
Full text linkThis report is an output of the project ôDetermination of high-potential aquaculture development areas and impact in Africa and Asiaö. This monograph is the case study for Bangladesh. Written in three parts, it describes the historical background, practices, stakeholder profiles, production levels, economic and institutional environment, policy issues, and prospects for aquaculture in the country. First, it documents the history and current status of the aquaculture in the country. Second, it assesses the technologies and approaches that either succeeded or failed to foster aquaculture development and discusses why. Third, it identifies the key reasons for aquaculture adoption.Freshwater aquaculture, Economic analysis, Trade, Ecosystems, Pond culture, Fish consumption, Food security, Policies, Regulations, Legislation, Socioeconomic aspects, Yield, Bangladesh,
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