On kinetic energy stabilized superconductivity in cuprates

The possibility of kinetic energy driven superconductivity in cuprates as was recently found in the $tJ$ model is discussed. We argue that the violation of the virial theorem implied by this result is serious and means that the description of superconductivity within the $tJ$ model is pathological.Comment: 3 pages, v2 includes additional reference

Plasmonic concentrator of magnetic field of light

We propose an efficient concentrator of the magnetic component of evanescent field of light for measuring magnetic responses of nanostructures. It is in the form of a tapered fiber probe, which in its final part has corrugations along the angular dimension and is coated with metal except for the aperture at the tip. Internal, azimuthally polarized illumination is concentrated into a subwavelength spot with a strong longitudinal magnetic component H-z. Within the visual range of wavelengths 400-700 nm, the energy density of H-z is up to 50 times larger than that of the azimuthal electric E-phi one. This dominant H-z contribution may be used for magnetic excitation of elementary cells of metamaterials with a single probe guiding a wide spectrum of generated plasmons

Large eddy simulation of plume dispersion behind an aircraft in the take-off phase

The aim of this paper is to provide an investigation, using large eddy simulation, into plume dispersion behind an aircraft in co-flowing take-off conditions. Validation studies of the computational model were presented by Aloysius and Wrobel (Environ Model Softw 24:929–937, 2009) and a study of the flow and dispersion properties of a double-engine aircraft jetwas presented by Aloysius et al. EEC/SEE/2007/001,EUROCONTROLExperimentalCentre, http://www.eurocontrol.int/eec/gallery/content/public/document/eec/report/2007/ 032_ALAQS_comparison_of_CFD_and_Lagrangian_dispersion_methods.pdf), in which only the engine was modelled. In this paper, the complete geometry of a Boeing 737 is modelled and investigated. The currentwork represents a contribution towards a better understanding of the source dynamics behind an airplane jet engine during the take-off and landing phases. The information provided from these simulations will be useful for future improvements of existing dispersion models

Homogenization of the Equations Governing the Flow Between a Slider and a Rough Spinning Disk

We have analyzed the behavior of the flow between a slider bearing and a hard-drive magnetic disk under two types of surface roughness. For both cases the length scale of the roughness along the surface is small as compared to the scale of the slider, so that a homogenization of the governing equations was performed. For the case of longitudinal roughness, we derived a one-dimensional lubrication-type equation for the leading behavior of the pressure in the direction parallel to the velocity of the disk. The coefficients of the equation are determined by solving linear elliptic equations on a domain bounded by the gap height in the vertical direction and the period of the roughness in the span-wise direction. For the case of transverse roughness the unsteady lubrication equations were reduced, following a multiple scale homogenization analysis, to a steady equation for the leading behavior of the pressure in the gap. The reduced equation involves certain averages of the gap height, but retains the same form of the usual steady, compressible lubrication equations. Numerical calculations were performed for both cases, and the solution for the case of transverse roughness was shown be in excellent agreement with a corresponding numerical calculation of the original unsteady equations

Towards the Development of a Risk Model for Unmanned Vessels Design and Operations

An unmanned merchant vessel seems to be escaping from the stage of idea exploration. Once the concept proofs its safety, it may become a part of maritime reality. Although the safety aspect of such a ship has been addressed by a handful of scholars, the problem remains open. This is mainly due to lack of knowledge regarding actual operational circumstances and design of unmanned ships, which are yet to be developed. In the attempt of bridging this gap, the risk analysis associated with unmanned ships needs to be carried out, where all relevant hazards and consequences are assessed and quantified in systematic manner. In this paper we present the results of a first step of such analysis, namely the hazard analysis associated with the unmanned ships. The list of hazards covers various aspects of unmanned shipping originating from both design and operational phases of vessel’s life. Subsequently the hazards and related consequences are organized in a casual manner, resulting in the development of a structure of a risk model