33,238 research outputs found
Press forming a 0/90 cross-ply advanced thermoplastic composite using the double-dome benchmark geometry
A pre-consolidated thermoplastic advanced composite cross-ply sheet comprised of two uniaxial plies orientated at 0/90° has been thermoformed using tooling based on the double-dome bench-mark geometry. Mitigation of wrinkling was achieved using springs to apply tension to the forming sheet rather than using a friction-based blank-holder. The shear angle across the surface of the formed geometry has been measured and compared with data collected previously from experiments on woven engineering fabrics. The shear behaviour of the material has been characterised as a function of rate and temperature using the picture frame shear test technique. Multi-scale modelling predictions of the material’s shear behaviour have been incorporated in finite element forming predictions; the latter are compared against the experimental results
A new quantum fluid at high magnetic fields in the marginal charge-density-wave system -(BEDT-TTF)Hg(SCN) (where ~K and Rb)
Single crystals of the organic charge-transfer salts
-(BEDT-TTF)Hg(SCN) have been studied using Hall-potential
measurements (K) and magnetization experiments ( = K, Rb). The data show
that two types of screening currents occur within the high-field,
low-temperature CDW phases of these salts in response to time-dependent
magnetic fields. The first, which gives rise to the induced Hall potential, is
a free current (), present at the surface of the sample.
The time constant for the decay of these currents is much longer than that
expected from the sample resistivity. The second component of the current
appears to be magnetic (), in that it is a microscopic,
quasi-orbital effect; it is evenly distributed within the bulk of the sample
upon saturation. To explain these data, we propose a simple model invoking a
new type of quantum fluid comprising a CDW coexisting with a two-dimensional
Fermi-surface pocket which describes the two types of current. The model and
data are able to account for the body of previous experimental data which had
generated apparently contradictory interpretations in terms of the quantum Hall
effect or superconductivity.Comment: 13 pages, 11 figure
Analytical Hartree-Fock gradients for periodic systems
We present the theory of analytical Hartree-Fock gradients for periodic
systems as implemented in the code CRYSTAL. We demonstrate how derivatives of
the integrals can be computed with the McMurchie-Davidson algorithm. Highly
accurate gradients with respect to nuclear coordinates are obtained for systems
periodic in 0,1,2 or 3 dimensions.Comment: accepted by International Journal of Quantum Chemistr
Spatial Relationship between Solar Flares and Coronal Mass Ejections
We report on the spatial relationship between solar flares and coronal mass
ejections (CMEs) observed during 1996-2005 inclusive. We identified 496
flare-CME pairs considering limb flares (distance from central meridian > 45
deg) with soft X-ray flare size > C3 level. The CMEs were detected by the Large
Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric
Observatory (SOHO). We investigated the flare positions with respect to the CME
span for the events with X-class, M-class, and C-class flares separately. It is
found that the most frequent flare site is at the center of the CME span for
all the three classes, but that frequency is different for the different
classes. Many X-class flares often lie at the center of the associated CME,
while C-class flares widely spread to the outside of the CME span. The former
is different from previous studies, which concluded that no preferred flare
site exists. We compared our result with the previous studies and conclude that
the long-term LASCO observation enabled us to obtain the detailed spatial
relation between flares and CMEs. Our finding calls for a closer flare-CME
relationship and supports eruption models typified by the CSHKP magnetic
reconnection model.Comment: 7 pages; 4 figures; Accepted by the Astrophysical Journa
Implications of Privacy Needs and Interpersonal Distancing Mechanisms for Space Station Design
The literature on privacy needs, personal space, interpersonal distancing, and crowding is reveiwed with special reference to spaceflight and spaceflight analogous conditions. A quantitative model is proposed for understanding privacy, interpersonal distancing, and performance. The implications for space station design is described
Implications of privacy needs and interpersonal distancing mechanisms for space station design
Privacy needs, or the need of people to regulate their degree of contact with one another, and interpersonal distancing mechanisms, which serve to satisfy these needs, are common in all cultures. Isolation, confinement, and other conditions accociated with space flight may at once accentuate privacy needs and limit the availability of certain common interpersonal contact. Loneliness occurs when people have less contact with one another than they desire. Crowding occurs when people have more contact with one another than they desire. Crowding, which is considered the greater threat to members of isolated and confined groups, can contribute to stress, a low quality of life, and poor performance. Drawing on the general literature on privacy, personal space, and interpersonal distancing, and on specialized literature on life aboard spacecraft and in spacecraft-analogous environments, a quantitative model for understanding privacy, interpersonal distancing, loneliness, and crowding was developed and the practical implications of this model for space station design were traced
Perceived quality of society
Drawing on evidence from across Europe, this report explores new ways in which policy can support and encourage high levels of wellbeing, using data from the European Social Survey. Much of the established evidence and analysis around wellbeing is based on a single measure – life satisfaction. This report combines contributions from City University London, the New Economics Foundation (NEF) and the University of Cambridge to explore new ways of understanding and measuring wellbeing
- …