1,811 research outputs found
Control of long-range correlations in turbulence
The character of turbulence depends on where it develops. Turbulence near
boundaries, for instance, is different than in a free stream. To elucidate the
differences between flows, it is instructive to vary the structure of
turbulence systematically, but there are few ways of stirring turbulence that
make this possible. In other words, an experiment typically examines either a
boundary layer or a free stream, say, and the structure of the turbulence is
fixed by the geometry of the experiment. We introduce a new active grid with
many more degrees of freedom than previous active grids. The additional degrees
of freedom make it possible to control various properties of the turbulence. We
show how long-range correlations in the turbulent velocity fluctuations can be
shaped by changing the way the active grid moves. Specifically, we show how not
only the correlation length but also the detailed shape of the correlation
function depends on the correlations imposed in the motions of the grid. Until
now, large-scale structure had not been adjustable in experiments. This new
capability makes possible new systematic investigations into turbulence
dissipation and dispersion, for example, and perhaps in flows that mimic
features of boundary layers, free streams, and flows of intermediate character.Comment: This paper has been accepted to Experiments in Fluids. 25 pages, 10
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Is it Good to Talk? Information Disclosure and Organisational Performance in the UK Incorporating evidence submitted on the DTI discussion paper 'High Performance Workplaces - Informing and Consulting Employees'
The disclosure of information by management to employees varies significantly between workplaces. The effects of this variance on organizational performance are analysed using WERS98 data. The results show that the impact of information disclosure on organisational performance is more complex than is often assumed in the literature. Overall, there is a significant impact, both direct and indirect, and this varies depending on the level of employee organisational commitment, the type of information disclosed, and the performance outcome involved. On the whole, the positive effects are less in union settings and in situations where unions are strong.
Spectrum of a magnetized strong-leg quantum spin ladder
Inelastic neutron scattering is used to measure the spin excitation spectrum
of the Heisenberg ladder material (CHN)CuBr in its
entirety, both in the gapped spin-liquid and the magnetic field induced
Tomonaga-Luttinger spin liquid regimes. A fundamental change of the spin
dynamics is observed between these two regimes. DMRG calculations
quantitatively reproduce and help understand the observed commensurate and
incommensurate excitations. The results validate long-standing quantum field
theoretical predictions, but also test the limits of that approach
Patterns of information disclosure and joint consultation in Great Britain: determinants and outcomes
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