Impact Absorbent Rapid Manufactured Structures (IARMS)

Rapid Manufacturing (RM) is increasingly becoming a viable manufacturing process due to dramatic advantages that it facilitates in the area of design complexity. Through the exploration of the design freedom afforded by RM, this paper introduces the concept and initial research surrounding Impact Absorbent Rapid Manufactured Structures (IARMS), with an application in sports personal protective equipment (PPE). Designs are based on the cellular structure of foams; the inherent advantages of the cellular structure are used as a basis to create IARMS that have the potential to be optimised for a specific impact absorbent response. The paper provides some initial results from compression testingMechanical Engineerin

Rapid Manufactured Textiles

Rapid Manufacturing (RM) is increasingly becoming a viable manufacturing process due to dramatic advantages that are achievable in the area of design complexity. Through the exploration of the design freedom, this paper introduces the concept of manufacturing textiles for potential smart and high performance textile applications. This paper discusses the current limitations associated with the manufacture of textiles through RM and presents a novel methodology for the generation of 3D conformal RM textile articles. The paper concludes that through RM it is entirely possible to manufacture a structure that incorporates drape and free movement properties directly comparable to conventional textiles.Mechanical Engineerin

Particle acceleration in tangential discontinuities by lower hybrid waves

We consider the role that the lower-hybrid wave turbulence plays in providing the necessary resistivity at collisionless reconnection sights. The mechanism for generating the waves is considered to be the lower-hybrid drift instability. We find that the level of the wave amplitude is sufficient enough to heat and accelerate both electrons and ions

Instabilities in neutrino-plasma density waves

One examines the interaction and possible resonances between supernova neutrinos and electron plasma waves. The neutrino phase space distribution and its boundary regions are analyzed in detail. It is shown that the boundary regions are too wide to produce non-linear resonant effects. The growth or damping rates induced by neutrinos are always proportional to the neutrino flux and $G_{{\rm F}}^{2}$.Comment: 9 pages, a few words modified to match PRD publicatio

SIRIS: a high resolution scanning infrared camera for examining paintings

The new SIRIS (Scanning InfraRed Imaging System) camera developed at the National Gallery in London allows highresolution images of paintings to be made in the near infrared region (900–1700 nm). Images of 5000 × 5000 pixels are made by moving a 320 × 256 pixel InGaAs array across the focal plane of the camera using two orthogonal translation stages. The great advantages of this camera over scanning infrared devices are its relative portability and that image acquisition is comparatively rapid – a full 5000 × 5000 pixel image can be made in around 20 minutes. The paper describes the development of the mechanical, optical and electronic components of the camera, including the design of a new lens. The software routines used to control image capture and to assemble the individual 320 × 256 pixel frames into a seamless mosaic image are also mentioned. The optics of the SIRIS camera have been designed so that the camera can operate at a range of resolutions; from around 2.5 pixels per millimetre on large paintings of up to 2000 × 2000 mm to 10 pixels per millimetre on smaller paintings or details of paintings measuring 500 × 500 mm. The camera is primarily designed to examine underdrawings in paintings; preliminary results from test targets and paintings are presented and the quality of the images compared with those from other cameras currently used in this field

An oceanographer?s guide to GOCE and the geoid

International audienceA review is given of the geodetic concepts necessary for oceanographers to make use of satellite gravity data to define the geoid, and to interpret the resulting product. The geoid is defined, with particular attention to subtleties related to the representation of the permanent tide, and the way in which the geoid is represented in ocean models. The usual spherical harmonic description of the gravitational field is described, together with the concepts required to calculate a geoid from the spherical harmonic coefficients. A brief description is given of the measurement system in the GOCE satellite mission, scheduled for launch shortly, followed by a description of a reference ellipsoid with respect to which the geoid may be calculated. Finally, a recipe is given for calculation of the geoid relative to any chosen ellipsoid, given a set of spherical harmonic coefficients and defining constants

Determining North Atlantic meridional transport variability from pressure on the western boundary: a model investigation.

In this paper we investigate the possibility of determining North Atlantic meridional transport variability using pressure on the western boundary, focusing on the 42degN latitude of the Halifax WAVE array. We start by reviewing the theoretical foundations of this approach. Next we present results from a model analysis, both statistical and dynamic, that demonstrate the feasibility of the approach. We consider how well we can quantify the meridional transport variability at 42degN given complete knowledge of bottom pressure across the basin, and to what degree this quantification is degraded by first ignoring the effect of intervening topography, and then by using only bottom pressure on the western boundary. We find that for periods of greater than one year we can recover more than 90% of the variability of the main overturning cell at 42degN using only the western boundary pressure, provided we remove the depth-average boundary pressure signal. This signal arises from a basin mode of bottom pressure variability, which has power at all timescales, but that does not in truth have a meridional transport signal associated with it, and from the geostrophic depth-independent compensation of the Ekman transport. An additional benefit of the removal of the depth-average pressure is that this high-frequency Ekman signal, which is essentially noise as far as monitoring the MOC for climatically important changes is concerned, is clearly separated from other modes

Undulation instability in a bilayer lipid membrane due to electric field interaction with lipid dipoles

Bilayer lipid membranes [BLMs] are an essential component of all biological systems, forming a functional barrier for cells and organelles from the surrounding environment. The lipid molecules that form membranes contain both permanent and induced dipoles, and an electric field can induce the formation of pores when the transverse field is sufficiently strong (electroporation). Here, a phenomenological free energy is constructed to model the response of a BLM to a transverse static electric field. The model contains a continuum description of the membrane dipoles and a coupling between the headgroup dipoles and the membrane tilt. The membrane is found to become unstable through buckling modes, which are weakly coupled to thickness fluctuations in the membrane. The thickness fluctuations, along with the increase in interfacial area produced by membrane buckling, increase the probability of localized membrane breakdown, which may lead to pore formation. The instability is found to depend strongly on the strength of the coupling between the dipolar headgroups and the membrane tilt as well as the degree of dipolar ordering in the membrane.Comment: 29 pages 8 fig