1,463 research outputs found
Automated operation of a home made torque magnetometer using LabVIEW
In order to simplify and optimize the operation of our home made torque
magnetometer we created a new software system. The architecture is based on
parallel, independently running instrument handlers communicating with a main
control program. All programs are designed as command driven state machines
which greatly simplifies their maintenance and expansion. Moreover, as the main
program may receive commands not only from the user interface, but also from
other parallel running programs, an easy way of automation is achieved. A
program working through a text file containing a sequence of commands and
sending them to the main program suffices to automatically have the system
conduct a complex set of measurements. In this paper we describe the system's
architecture and its implementation in LabVIEW.Comment: 6 pages, 7 figures, submitted to Rev. Sci. Inst
The effects of manufacturing tolerances and assembly force on the volumetric wear at the taper junction in modular total hip arthroplasty
Item does not contain fulltextFretting and corrosion at the taper-head interface in total hip arthroplasty has been reported as a potential cause of early failure of the implant system. The finite element (FE) method can be used to study the mechanics at the taper junction that are difficult to assess experimentally. Taper mismatch is one of the factors that can influence the performance of the taper junction. In this study we have assessed the effect of taper mismatch, in combination with assembly force on the volumetric wear. The study showed that higher assembly forces and smaller mismatches result in the least volumetric wear
Alternative optical concept for electron cyclotron emission imaging
The implementation of advanced electron cyclotron emission imaging (ECEI) systems on tokamak experiments has revolutionized the diagnosis of magnetohydrodynamic (MHD) activities and improved our understanding of instabilities, which lead to disruptions. It is therefore desirable to have an ECEI system on the ITER tokamak. However, the large size of optical components in presently used ECEI systems have, up to now, precluded the implementation of an ECEI system on ITER. This paper describes a new optical ECEI concept that employs a single spherical mirror as the only optical component and exploits the astigmatism of such a mirror to produce an image with one-dimensional spatial resolution on the detector. Since this alternative approach would only require a thin slit as the viewing port to the plasma, it would make the implementation of an ECEI system on ITER feasible. The results obtained from proof-of-principle experiments with a 125 GHz microwave system are presented. (C) 2014 AIP Publishing LLC
CFD study of Jet Impingement Test erosion using Ansys Fluent® and OpenFOAM®
The initial aim of this study was to compare OpenFoam and Ansys Fluent in order to verify OpenFoam’s Lagrangian Library and erosion capabilities. However, it was found that previous versions of Fluent have been providing wrong results for the discrete phase and the differences with the latest version (Ansys Fluent 15) are shown. A Submerged Jet Impingement Test is an effective method for studying erosion created by solid particles entrained in a liquid. When considering low particle concentrations a Lagrangian modeling of the particulate phase is a reasonable approach. Proper linkage between OpenFOAM’s Lagrangian library and the solver pimpleFoam for incompressible transient flows allows two-phase simulations to be undertaken for comparison with Ansys Fluent with the aim of verifying OpenFoam’s accuracy. Steady state convergence for the fluid flow is first accomplished and the results are compared, confirming a good agreement between the two packages. A transient simulation was then set up and spherical particles incorporated into the fluid flow. An assessment of the two codes’ discrete phase models was carried out, focusing on the differences between impact angles and velocities yielded at the impingement plate’s surface employing a similar strategy to that outlined first by Hattori et al. (2008) and later by Gnanavelu et al. (2009, 2011). In the comparison of OpenFoam with the latest version of Fluent, the main differences between the injection models are highlighted and the coupling possibilities between phases are taken into consideration. Agreement between trends for both impact angles and velocities is satisfactory when the last version of the commercial package is considered and the average discrepancy between numerical values is very low, verifying OpenFoam’s Lagrangian library. Two different Jet Impingement Test configurations are also compared and the differences highlighted
Observable Dirac-type singularities in Berry's phase and the monopole
The physical reality and observability of 2n\pi Berry phases, as opposed to
the usually considered modulo 2\pi topological phases is demonstrated with the
help of computer simulation of a model adiabatic evolution whose parameters are
varied along a closed loop in the parameter space. Using the analogy of Berry's
phase with the Dirac monopole, it is concluded that an interferometer loop
taken around a magnetic monopole of strength n/2 yields an observable 2n\pi
phase shift, where n is an integer. An experiment to observe the effect is
proposed.Comment: 12 pages Latex, 3 postscript figures; submitted to Physical Review
Letters 15 September 2000; revised 19 November 200
Nuclear Magnetic Resonance and Hyperfine Structure
Contains reports on four research projects
Придністровський конфлікт: чинники існування напруги
Стаття присвячена аналізу та систематизації чинників, що
обумовлюють збереження статус-кво у процесі придністровського
врегулювання на глобальному, регіональному та локальному рівні.The article is devoted to the analysis and systematization of factors
leading to the preservation of the status-quo in the Transnistrian
settlement process on global, regional and local level
Measuring Pancharatnam's relative phase for SO(3) evolutions using spin polarimetry
In polarimetry, a superposition of internal quantal states is exposed to a
single Hamiltonian and information about the evolution of the quantal states is
inferred from projection measurements on the final superposition. In this
framework, we here extend the polarimetric test of Pancharatnam's relative
phase for spin proposed by Wagh and Rakhecha [Phys. Lett. A {\bf 197},
112 (1995)] to spin undergoing noncyclic SO(3) evolution. We
demonstrate that the output intensity for higher spin values is a polynomial
function of the corresponding spin intensity. We further propose a
general method to extract the noncyclic SO(3) phase and visibility by rigid
translation of two spin flippers. Polarimetry on higher spin states
may in practice be done with spin polarized atomic beams.Comment: New title, minor corrections, journal reference adde
Ultrafast geometric manipulation of electron spin and detection of the geometric phase via Faraday rotation spectroscopy
Time-resolved Faraday rotation spectroscopy is currently exploited as a
powerful technique to probe spin dynamics in semiconductors. We propose here an
all-optical approach to geometrically manipulate electron spin and to detect
the geometric phase by this type of extremely sensitive experiment. The global
nature of the geometric phase can make the quantum manipulation more stable,
which may find interesting application in quantum devices.Comment: 4 pages, 3 figures, to appear in Phys. Rev.
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