197,451 research outputs found
Measuring magnetic correlations in nanoparticle assemblies
No full textWe illustrate how to extract correlations between magnetic moments in assemblies of nanoparticles from, e.g., electron holography data providing the combined knowledge of particle size distribution, inter-particle distances, and magnitude and orientation of each magnetic moment within a nanoparticle superstructure, We show, based on simulated data, how to build a radial/angular pair distribution function f(r,θ) encoding the spatial and angular difference between every pair of magnetic moments. A scatter-plot of f(r,θ) reveals the degree of structural and magnetic order present, and hence provides a measure of the strength and range of magnetic correlations
Sejlkajakker i Danmark
No full textArtiklens forfatter, Svend Frandsen, skildrer sejlkajakkens historie i Danmark med den indsigt og forståelse, der følger af at han selv hører til idrættens aktive udøvere. Sejlkajakker blev især populære til tursejlads i 1930'rne -i en tid hvor masseproducerede billige joller endnu ikke fandtes
Magnetic dipolar ordering and hysteresis of geometrically defined nanoparticle clusters
No full textMagnetic nanoparticle clusters have several biomedical and engineering applications, and revealing the basic interplay between particle configuration and magnetic properties is important for tuning the clusters for specific uses. Here, we consider the nanoparticles as macrospins and use computer simulations to determine their magnetic configuration when placed at the vertices of various polyhedra. We find that magnetic dipoles of equal magnitude arrange in flux-closed vortices on a layer basis, giving the structures a null remanent magnetic moment. Assigning a toroidal moment to each layer, we find that the geometrical arrangement, i.e., “triangular packing” vs. “square packing,” of the moments in the adjacent layer determines whether the flux-closed layers are ferrotoroidal (co-rotating vortices) or antiferrotoroidal (counter-rotating vortices). Interestingly, upon adding a single magnetic moment at the center of the polyhedra, the central moment relaxes along one of the principal axes and induces partial alignment of the surrounding moments. The resulting net moment is up to nearly four times that of the single moment added. Furthermore, we model quasi-static hysteresis loops for structures with and without a central moment. We find that a central moment ensures an opening of the hysteresis loop, and the resultant loop areas are typically many-fold larger compared to the same structure without a central moment
NEWP 32 Transport green corridors: literature review, options appraisal and opportunity mapping
No full textFourth lepton family is natural in technicolor
No full textImagine discovering a new fourth family of leptons at the Large Hadron Collider (LHC) but no signs of an associated fourth family of quarks. What would that imply? An intriguing possibility is that the new fermions needed to compensate for the new leptons gauge anomalies simultaneously address the big hierarchy problem of the standard model. A natural way to accomplish such a scenario is to have the Higgs itself be a composite of these new fermions. This is the setup we are going to investigate in this paper using as a template minimal walking technicolor. We analyze a general heavy neutrino mass structure with and without mixing with the standard model families. We also analyze the LHC potential to observe the fourth lepton family in tandem with the new composite Higgs dynamics. We finally introduce a model uniting the fourth lepton family and the technifermion sector at higher energies. © 2010 The American Physical Society
Cosmic-ray sum rules
No full textWe introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays; we show how they can be used to predict the positron fraction at energies not yet explored by current experiments, and to constrain specific models. © 2011 American Physical Society
Svitzer gennem 125 år
No full textLise Astrup Frandsen er uddannet etnolog og arbejdede fra sommeren 2007 til foråret 2008 på en jubilæumsbog om SVITZER. 1 Bogen var rekvireret af SVITZER gennem Københavns Bymuseum i anledning af firmaets 175 års virke. Virksomheden blev født i 1833 og er i dag en af verdens ældste og største ekspertvirksomheder i bjergning, bugsering og andre specialopgaver til søs. Denne artikel bygger på arbejdet, der udmøntede sig i bogen SVITZER safety and support at sea 1833-2008. Arbejdet er baseret på sekundært kildemateriale om den historiske udvikling, mens de nyere afsnit bygger på feltarbejde og interviews med medarbejdere på flere niveauer i SVITZER. Fokus i artiklen er virksomhedens udvikling i store træk, herunder større omvæltninger og udfordringer op til i dag
CADET-Julia: Version 0.2.0
No full textCADET-Julia is a numerical solver for a family of chromatography models and is a streamlined and computationally efficient adaption of the more comprehensive CADET-Core project, and is based on a spatial Discontinuous Galerkin Spectral Element Method (DGSEM), similar to the DGSEM implemented in CADET-Core. If you find it useful for your own work, we would appreciate acknowledgements of this software and citations of our papers: Jesper Frandsen, Jan M. Breuer, Eric von Lieres, Johannes Schmölder, Jakob K. Huusom, Krist V. Gernaey, Jens Abildskov: Discontinuous Galerkin spectral element method for continuous chromatography: Application to the Lumped Rate Model without pores, Computer Aided Chemical Engineering, 53, 3325-3330
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