99 research outputs found

    To Investigate Electrode Wear Rate on Steel Material with Different Parameters on EDM Machine

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    The studies of an experimental investigation evaluate the effects of EDM machining parameters such as MRR, EWR with two different electrode materials. The process parameters such as Input current, Pulse on time and duty cycle keeping flushing pressure constant. With the use of Design of Experiment The full factorial design of experiment (L2)4 is used to study the effects of machining parameters on die steel material. Investigations selected the machine Model Electra plus leader-1-znc Electra machine, through practical, investigation the output parameters of EDM increases with the increase in input current and the best machining rates are achieved with copper electrodes, better surface roughness compare to brass electrode. A brass electrode with higher input current and maximum pulse on time resulted in more EWR compared to copper electrodes

    Nucleon axial form factors from two-flavour Lattice QCD

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    We present preliminary results on the axial form factor GA(Q2)G_A(Q^2) and the induced pseudoscalar form factor GP(Q2)G_P(Q^2) of the nucleon. A systematic analysis of the excited-state contributions to form factors is performed on the CLS ensemble `N6' with mπ=340 MeVm_\pi = 340 \ \text{MeV} and lattice spacing a∼0.05 fma \sim 0.05 \ \text{fm}. The relevant three-point functions were computed with source-sink separations ranging from ts∼0.6 fmt_s \sim 0.6 \ \text{fm} to $t_s \sim \ 1.4 \ \text{fm}$. We observe that the form factors suffer from non-trivial excited-state contributions at the source-sink separations available to us. It is noted that naive plateau fits underestimate the excited-state contributions and that the method of summed operator insertions correctly accounts for these effects.Comment: 7 pages, 12 figures; talk presented at Lattice 2014 -- 32nd International Symposium on Lattice Field Theory, 23-28 June, 2014, Columbia University New York, N

    SU(2) low-energy constants from mixed-action lattice QCD

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    An analysis of the pion mass and pion decay constant is performed using mixed-action lattice QCD calculations with domain-wall valence quarks on ensembles of rooted, staggered n(f) = 2 + 1 configurations generated by the MILC Collaboration. Calculations were performed at two lattice spacings of b approximate to 0.125 fm and b approximate to 0.09 fm, at two strange quark masses, multiple light quark masses, and a number of lattice volumes. The ratios of light quark to strange quark masses are in the range 0.1 \u3c = m(l)/m(s) \u3c = 0.6, while pion masses are in the range 235 less than or similar to m(pi) less than or similar to 680 MeV. A two-flavor chiral perturbation theory analysis of the lattice QCD calculations constrains the Gasser-Leutwyler coefficients (l) over bar (3) and (l) over bar (4) to be (l) over bar (3) = 4.04(40)((73)(55)) and (l) over bar (4) = 4.30(51)((84)(60)). All systematic effects in the calculations are explored, including those from the finite lattice space-time volume, the finite lattice spacing, and the finite fifth dimension in the domain-wall quark action. A consistency is demonstrated between a chiral perturbation theory analysis at fixed lattice spacing combined with a leading order continuum extrapolation, and the mixed-action chiral perturbation theory analysis which explicitly includes the leading order discretization effects. Chiral corrections to the pion decay constant are found to give f(pi)/f = 1.062(26)((42)(40)) where f is the decay constant in the chiral limit, and when combined with the experimental determination of f(pi) results in a value of f = 122.8(3.0((4.6)(4.8)) MeV. The most recent scale setting by the MILC Collaboration yields a postdiction of f(pi) = 128.2(3.6)((4.4)(6.0))((1.2)(3.3)) MeV at the physical pion mass. A detailed error analysis indicates that precise calculations at lighter pion masses is the single most important systematic to address to improve upon the present work

    Suppression of excited-state effects in lattice determination of nucleon electromagnetic form factors

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    We study the ability of a variety of fitting techniques to extract the ground state matrix elements of the vector current from ratios of nucleon three- and two-point functions that contain contaminations from excited states. Extending our high-statistics study of nucleon form factors, we are able to demonstrate that the treatment of excited-state contributions in conjunction with approaching the physical pion mass has a significant impact on the Q2Q^2-dependence of the form factors.Comment: 7 pages, 5 pdf figures; talk presented at Lattice 2014 -- 32nd International Symposium on Lattice Field Theory, 23-28 June, 2014, Columbia University New York, N

    Simultaneous assessment of rodent behavior and neurochemistry using a miniature positron emission tomograph

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    Positron emission tomography (PET) neuroimaging and behavioral assays in rodents are widely used in neuroscience. PET gives insights into the molecular processes of neuronal communication, and behavioral methods analyze the actions that are associated with such processes. These methods have not been directly integrated, because PET studies in animals have until now required general anesthesia to immobilize the subject, which precludes behavioral studies. We present a method for imaging awake, behaving rats with PET that allows the simultaneous study of behavior. Key components include the 'rat conscious animal PET' or RatCAP, a miniature portable PET scanner that is mounted on the rat's head, a mobility system that allows considerable freedom of movement, radiotracer administration techniques and methods for quantifying behavior and correlating the two data sets. The simultaneity of the PET and behavioral data provides a multidimensional tool for studying the functions of different brain regions and their molecular constituents. © 2011 Nature America, Inc. All rights reserved
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