oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Introducing discussion into multilingual mathematics classrooms: An issue of code switching?  [cached]
Lyn Webb,Paul Webb
Pythagoras , 2011, DOI: 10.4102/pythagoras.v0i67.71
Abstract: The Department of Education in South Africa advocates collaborative and constructivist learning; however, observations indicate that little discussion occurs in most multilingual mathematics classes. In this paper we draw on a pilot study set in the Eastern Cape where teachers were introduced to the theory and practice of exploratory talk, and then tasked to perform an action research project on introducing discussion in their own multilingual mathematics classrooms. The results of the study suggest some successes in terms of teachers initiating exploratory talk and highlight the fact that these successes were only achieved where code switching between English and isiXhosa formed an integral part of the process.
Introducing ADAPTSMOOTH, a new code for the adaptive smoothing of astronomical images  [PDF]
Stefano Zibetti
Physics , 2009,
Abstract: We introduce and publicly release a new code, ADAPTSMOOTH, which serves to smooth astronomical images in an adaptive fashion, in order to enhance the signal-to-noise ratio (S/N). The adaptive smoothing scheme allows to take full advantage of the spatially resolved photometric information contained in an image in that at any location the minimal smoothing is applied to reach the requested S/N. Support is given to match more images on the same smoothing length, such that proper estimates of local colours can be done, with a big potential impact on multi-wavelength studies of extended sources (galaxies, nebulae). Different modes to estimate local S/N are provided. In addition to classical arithmetic-mean averaging mode, the code can operate in median averaging mode, resulting in a significant enhancement of the final image quality and very accurate flux conservation. To this goal also other code options are implemented and discussed in this paper. Finally, we analyze in great detail the effect of the adaptive smoothing on galaxy photometry, in particular in terms of surface brightness (SB) profiles and aperture photometry: deviations in SB with respect to the original image can be limited to <0.01 mag, with flux difference in apertures of less than 0.001 mag.
Introducing PHAEDRA: a new spectral code for simulations of relativistic magnetospheres  [PDF]
Kyle Parfrey,Andrei M. Beloborodov,Lam Hui
Physics , 2011, DOI: 10.1111/j.1365-2966.2012.20969.x
Abstract: We describe a new scheme for evolving the equations of force-free electrodynamics, the vanishing-inertia limit of magnetohydrodynamics. This pseudospectral code uses global orthogonal basis function expansions to take accurate spatial derivatives, allowing the use of an unstaggered mesh and the complete force-free current density. The method has low numerical dissipation and diffusion outside of singular current sheets. We present a range of one- and two-dimensional tests, and demonstrate convergence to both smooth and discontinuous analytic solutions. As a first application, we revisit the aligned rotator problem, obtaining a steady solution with resistivity localised in the equatorial current sheet outside the light cylinder.
On the geometry of output-code multi-class learning  [PDF]
Maria Florina Balcan,Travis Dick,Yishay Mansour
Computer Science , 2015,
Abstract: We analyze the popular multi-class algorithmic techniques of one-vs-all and error correcting output-codes, and show the surprising result that under the assumption that they are successful (at learning from labeled data), and under an additional mild distributional assumption, we can learn from unlabeled data (up to a permutation of the labels). The key point is that in cases where they work, these techniques implicitly assume structure on how the classes are related. We show how to exploit this relationship both in the case where the codewords are well separated (which includes the one-vs-all case) and in the case where the code matrix has the property that each bit of the codewords is important for distinguishing at least one class from impossible inputs.
Introducing ZEUS-MP: A 3D, Parallel, Multiphysics Code for Astrophysical Fluid Dynamics  [PDF]
Michael L. Norman
Physics , 2000,
Abstract: We describe ZEUS-MP: a Multi-Physics, Massively-Parallel, Message-Passing code for astrophysical fluid dynamics simulations in 3 dimensions. ZEUS-MP is a follow-on to the sequential ZEUS-2D and ZEUS-3D codes developed and disseminated by the Laboratory for Computational Astrophysics (lca.ncsa.uiuc.edu) at NCSA. V1.0 released 1/1/2000 includes the following physics modules: ideal hydrodynamics, ideal MHD, and self-gravity. Future releases will include flux-limited radiation diffusion, thermal heat conduction, two-temperature plasma, and heating and cooling functions. The covariant equations are cast on a moving Eulerian grid with Cartesian, cylindrical, and spherical polar coordinates currently supported. Parallelization is done by domain decomposition and implemented in F77 and MPI. The code is portable across a wide range of platforms from networks of workstations to massively parallel processors. Some parallel performance results are presented as well as an application to turbulent star formation.
Study on Optical Properties of Fiber Bundle Coupling LD Output Beams
光纤耦合LD输出光场特性研究

LI Ai-yun,WANG Xiao-ying,
李爱云
,王晓颖

光子学报 , 2007,
Abstract: The intensity distribution of fiber bundle coupling LD output beams is discussed.The optical field distribution of output end of fiber is analyzed based on the mode theory of the fiber transmit.The optical field distribution of output end of fiber is measured and numerically simulated,and the approximate expression is given.The intensity distribution of fiber bundle coupling LD output beams is numerically simulated and experimentally studied.The simulation results agreed well with the experimental ones.The results shows the intensity distribution of output end of fiber is a semi Gaussian distribute middle in Gaussian distribution and geometrical distribution.
Sub-Classifier Construction for Error Correcting Output Code Using Minimum Weight Perfect Matching  [PDF]
Patoomsiri Songsiri,Thimaporn Phetkaew,Ryutaro Ichise,Boonserm Kijsirikul
Computer Science , 2013,
Abstract: Multi-class classification is mandatory for real world problems and one of promising techniques for multi-class classification is Error Correcting Output Code. We propose a method for constructing the Error Correcting Output Code to obtain the suitable combination of positive and negative classes encoded to represent binary classifiers. The minimum weight perfect matching algorithm is applied to find the optimal pairs of subset of classes by using the generalization performance as a weighting criterion. Based on our method, each subset of classes with positive and negative labels is appropriately combined for learning the binary classifiers. Experimental results show that our technique gives significantly higher performance compared to traditional methods including the dense random code and the sparse random code both in terms of accuracy and classification times. Moreover, our method requires significantly smaller number of binary classifiers while maintaining accuracy compared to the One-Versus-One.
Dynamical evolution of massive black holes in galactic-scale N-body simulations - introducing the regularized tree code "rVINE"  [PDF]
S. J. Karl,S. J. Aarseth,T. Naab,M. G. Haehnelt,R. Spurzem
Physics , 2015, DOI: 10.1093/mnras/stv1453
Abstract: We present a hybrid code combining the OpenMP-parallel tree code VINE with an algorithmic chain regularization scheme. The new code, called "rVINE", aims to significantly improve the accuracy of close encounters of massive bodies with supermassive black holes in galaxy-scale numerical simulations. We demonstrate the capabilities of the code by studying two test problems, the sinking of a single massive black hole to the centre of a gas-free galaxy due to dynamical friction and the hardening of a supermassive black hole binary due to close stellar encounters. We show that results obtained with rVINE compare well with NBODY7 for problems with particle numbers that can be simulated with NBODY7. In particular, in both NBODY7 and rVINE we find a clear N-dependence of the binary hardening rate, a low binary eccentricity and moderate eccentricity evolution, as well as the conversion of the galaxy's inner density profile from a cusp to a a core via the ejection of stars at high velocity. The much larger number of particles that can be handled by rVINE will open up exciting opportunities to model stellar dynamics close to SMBHs much more accurately in a realistic galactic context. This will help to remedy the inherent limitations of commonly used tree solvers to follow the correct dynamical evolution of black holes in galaxy scale simulations.
Automatic Fragmentation and Storage of Code in Component Repository w.r.t their Input and Output Interfaces: A Tool  [PDF]
Pankaj Vohra,,Ashima Singh
International Journal of Innovative Technology and Exploring Engineering , 2013,
Abstract: Develop once, Use once is the common approach followed by software developers in software industry. Lot of software development effort, cost as well as time is wasted if the software components can’t be reused further. These efforts can be saved by reusing available components. In order to increase the availability of reusable components (with or for reuse), we need an effective component storage structure i.e. Repository and also automatic component addition and extraction from Component Repository. Auto-Detect-Fragment-Store is a staged technique which is used for the automatic storage and retrieval of source-code components. A component repository is constructed which stores automatically, fragmented code on the basis of inputs and outputs. This work is an effort towards automating component storage, its addition and retrieval in a way component can be reused and software reusability is enhanced.
Effect of introducing Bt gene in cotton on biochemical content of vascular bundle sap of cotton leaf and reproduction of Bemisia tabaci (Gennadius)
外源Bt基因导入对棉花叶片维管束汁液的生化物质含量及烟粉虱种群增殖的影响

ZHOU Fu-Cai,REN Shun-Xiang,CHEN De-Hua,LI Chuan-Ming,
周福才
,任顺祥,陈德华,李传明

中国生态农业学报 , 2008,
Abstract: Using transgenic Bt cotton "Guokang 22" and conventional parental cotton "Simian No.3" as tested varieties,the effect of introducing Bt gene on physiological indices of vascular bundle sap of cotton leaf and reproduction of Bemisia tabaci(Gennadius) was studied.The results show that transgenic Bt cotton "Guokang 22" contains more soluble sugar in vascular bundle sap both at seedling and flowering stages than the conventional parental cotton "Simian No.3".Tannin content in vascular bundle sap of "Guokang 22" is lower than that of "Simian No.3" at seedling stage,but not significantly different at flowering stage.Although no significant difference exists in total free amino acid content between two varieties,some amino acids(including glutamic acid,proline and alanine) that are closely related to B.tabaci metabolism are significantly higher in "Guokang 22" than in "Simian No.3" at flowering stage.No gossypol is detected from the sap at both seeding and flowering stages.The intrinsic rates of increase(rm) of B-type B.tabaci feeding on the leaves of trangenic Bt cotton "Guokang 22" at seeding and flowering stages are respectively 13.7% and 20.2% higher than those feeding on conventional parental cotton "Simian No.3".This indicates that the introduction of foreign Bt gene produces profound effect on the syntheses of soluble sugars,free amino acids and anti-biosies,and thus on the population of B.tabaci.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.