Abstract
SummaryHadoop MapReduce has become a major computing technology in support of big data analytics. The Hadoop framework has over 190 configuration parameters, and some of them can have a significant effect on the performance of a Hadoop job. Manually tuning the optimum or near optimum values of these parameters is a challenging task and also a time consuming process. This paper optimizes the performance of Hadoop by automatically tuning its configuration parameter settings. The proposed work first employs gene expression programming technique to build an objective function based on historical job running records, which represents a correlation among the Hadoop configuration parameters. It then employs particle swarm optimization technique, which makes use of the objective function to search for optimal or near optimal parameter settings. Experimental results show that the proposed work enhances the performance of Hadoop significantly compared with the default settings. Moreover, it outperforms both rule‐of‐thumb settings and the Starfish model in Hadoop performance optimization. © 2016 The Authors. Concurrency and Computation: Practice and Experience Published by John Wiley & Sons Ltd.
Highlights
Rare earth element oxysul de phosphors have been intensely investigated since they were rst reported over 70 years ago[1] and have found widespread applications for a variety of industrial uses
Gd2O2S:Tb3+ is the most frequently employed phosphor in X-ray intensifying screens,[9] its high density of 7.44 g cmÀ3 makes it an effective trap of the incident X-ray photon, allied with this are its further attributes of high intrinsic conversion efficiency (20%) and high quantum yield of Tb3+
We previously presented an explanation of the photo luminescence (PL) spectra of Y2O2S:Tb3+ and Gd2O2S:Tb3+;3–6 this work is an extension to (Y1ÀxGdx)2O2S:Tb3+ materials with different Y3+/Gd3+ ratios
Summary
Rare earth element oxysul de phosphors have been intensely investigated since they were rst reported over 70 years ago[1] and have found widespread applications for a variety of industrial uses. E-mail: jack.silver@ brunel.ac.uk bDepartment of Chemical Engineering, Munster University of Applied Sciences, Stegerwaldstrasse, 39, Steinfurt, D-48565, Germany from X-ray wavelengths to visible light, and rather short decay times.[7] the properties of the green emitting Gd2O2S:Tb3+ were found to be superior to other, earlier generation X-ray phosphors such as (ZnCd)S:Ag or CaWO4 Both Gd2O2S:Tb3+ and Gd2O2S:Pr3+ phosphors are used for XCT (X-ray computed tomography) as scintillator materials.[7,8] Gd2O2S:Tb3+ is the most frequently employed phosphor in X-ray intensifying screens,[9] its high density of 7.44 g cmÀ3 makes it an effective trap of the incident X-ray photon, allied with this are its further attributes of high intrinsic conversion efficiency (20%) and high quantum yield of Tb3+. Several studies on the parent compounds Gd2O2S:Tb3+ and Y2O2S:Tb3+ have been published on the synthesis of nanometre sized phosphor particles this is to our knowledge the rst report of such materials having different Y3+/Gd3+ ratios
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