7,923 research outputs found
Homogeneous cooling of rough, dissipative particles: Theory and simulations
We investigate freely cooling systems of rough spheres in two and three
dimensions. Simulations using an event driven algorithm are compared with
results of an approximate kinetic theory, based on the assumption of a
generalized homogeneous cooling state. For short times , translational and
rotational energy are found to change linearly with . For large times both
energies decay like with a ratio independent of time, but not
corresponding to equipartition. Good agreement is found between theory and
simulations, as long as no clustering instability is observed. System
parameters, i.e. density, particle size, and particle mass can be absorbed in a
rescaled time, so that the decay of translational and rotational energy is
solely determined by normal restitution and surface roughness.Comment: 10 pages, 10 eps-figure
Aspects of management options for pasture-based dairy production stocked at two cows per hectare
End of project reportWhite clover in association with Rhizobium bacteria have the capacity to fix or convent atmospheric N into plant available N. This can make a considerable contribution to sward productivity. One of the objectives of this experiment was to determine the upper carrying capacity of grass-white clover swards receiving 90 kg fertilizer N/ha. A second objective was to examine the impact of grass-clover swards on mineral-N in the soil and losses of nitrate-N from soil to drainage water during the winter. This experiment was conducted at Solohead Research Farm. There were three treatments: (i) A grass-only treatment (FN) stocked at 2.0 cows per ha in 2003 and 2.2 cows per ha during 2004, 2005 and 2006. This treatment received an average of 226 kg per ha of fertilizer N per year during these years. (ii) A grass-clover treatment (WC) stocked at the same rates as FN and received an average of 90 kg per ha of fertilizer N per year during the experiment. (iii) A grass-only treatment (CC) that was gradually converted over to grass-clover during the experiment and stocked at 2.0 cows per ha throughout the experiment. Fertilizer N input was gradually lowered from 150 kg per ha in 2003 to a target of 90 kg per ha in 2005 and 2006
Energy flows in vibrated granular media
We study vibrated granular media, investigating each of the three components
of the energy flow: particle-particle dissipation, energy input at the
vibrating wall, and particle-wall dissipation. Energy dissipated by
interparticle collisions is well estimated by existing theories when the
granular material is dilute, and these theories are extended to include
rotational kinetic energy. When the granular material is dense, the observed
particle-particle dissipation rate decreases to as little as 2/5 of the
theoretical prediction. We observe that the rate of energy input is the weight
of the granular material times an average vibration velocity times a function
of the ratio of particle to vibration velocity. `Particle-wall' dissipation has
been neglected in all theories up to now, but can play an important role when
the granular material is dilute. The ratio between gravitational potential
energy and kinetic energy can vary by as much as a factor of 3. Previous
simulations and experiments have shown that E ~ V^delta, with delta=2 for
dilute granular material, and delta ~ 1.5 for dense granular material. We
relate this change in exponent to the departure of particle-particle
dissipation from its theoretical value.Comment: 19 pages revtex, 10 embedded eps figures, accepted by PR
X-ray Polarization Signatures of Compton Scattering in Magnetic Cataclysmic Variables
Compton scattering within the accretion column of magnetic cataclysmic
variables (mCVs) can induce a net polarization in the X-ray emission. We
investigate this process using Monte Carlo simulations and find that
significant polarization can arise as a result of the stratified flow structure
in the shock-ionized column. We find that the degree of linear polarization can
reach levels up to ~8% for systems with high accretion rates and low
white-dwarf masses, when viewed at large inclination angles with respect to the
accretion column axis. These levels are substantially higher than previously
predicted estimates using an accretion column model with uniform density and
temperature. We also find that for systems with a relatively low-mass white
dwarf accreting at a high accretion rate, the polarization properties may be
insensitive to the magnetic field, since most of the scattering occurs at the
base of the accretion column where the density structure is determined mainly
by bremsstrahlung cooling instead of cyclotron cooling.Comment: 7 pages, 8 figures, accepted by MNRA
The need for best practice standards in electronic governance of patient medical records to facilitate innovation
Background : Optimising the use of electronic data offers many opportunities to health services, particularly in rural and remote areas. These include reducing the effect of distance on access to clinical information and sharing information where there are multiple service providers for a single patient. The increasing compilation of large electronic databases of patient information and the ease with which electronic information can be transferred has raised concerns about the privacy and confidentiality of such records.Aims & rationale/Objectives : This review aims to identify legal and ethical standards for areas of electronic governance where a lack of clarity may currently impede innovation in health service delivery.Methods : This paper describes best practices for storage and transfer of electronic patient data based on an examination of Australian legislative requirements and a review of a number of current models. This will firstly allow us to identify basic legal requirements of electronic governance as well as areas of ambiguity not fully addressed by legislation. An examination of current models will suggest recommendations for best practice in areas lacking sufficient legal guidance.Principal findings : We have identified the following four areas of importance, and shall discuss relevant details:1) Patients\u27 right of ownership to electronic patient records. 2) Custodial issues with data stored in centralised health care institutions 3) IT Security, including hierarchical level access, data encryption, data transfer standards and physical security 4) Software applications usage.Discussion : Our examination of several models of best practice for the transfer of electronic patient data, both in Australia and internationally, identifies and clarifies many unresolved issues of electronic governance. This paper will also inform future policy in this area.Implications : Clarification will facilitate the future development of beneficial technology-based innovations by rural health services.Presentation type : Poster <br /
Inelastic Collapse of Three Particles
A system of three particles undergoing inelastic collisions in arbitrary
spatial dimensions is studied with the aim of establishing the domain of
``inelastic collapse''---an infinite number of collisions which take place in a
finite time. Analytic and simulation results show that for a sufficiently small
restitution coefficient, , collapse can
occur. In one dimension, such a collapse is stable against small perturbations
within this entire range. In higher dimensions, the collapse can be stable
against small variations of initial conditions, within a smaller range,
.Comment: 6 pages, figures on request, accepted by PR
Dynamics of inelastically colliding rough spheres: Relaxation of translational and rotational energy
We study the exchange of kinetic energy between translational and rotational
degrees of freedom for inelastic collisions of rough spheres. Even if
equipartition holds in the initial state it is immediately destroyed by
collisions. The simplest generalisation of the homogeneous cooling state allows
for two temperatures, characterizing translational and rotational degrees of
freedom separately. For times larger than a crossover frequency, which is
determined by the Enskog frequency and the initial temperature, both energies
decay algebraically like with a fixed ratio of amplitudes, different
from one.Comment: 5 pages, RevTeX, 2 eps figures, slightly expanded discussion, new
figures with dimensionless units, added references, accepted for publication
in PRE as a Rapid Com
The Joint Vienna Institute
"How does the intellectual role played by international training organisations fit into the contemporary architecture of global governance? The international diffusion of economic policy ideas represents one of the core dimensions of contemporary global governance, which has generated heated controversy in recent years with international institutions such as the International Monetary Fund (IMF) and the World Bank castigated for championing a ‘one-size-fits-all’ brand of neoliberal economic reform. Yet while substantial scholarly attention has focused on analysing the effects of the formal compliance mechanisms that the IMF and the World Bank rely on to implement neoliberal policy changes in borrowing countries, such as loan conditionality, less attention has been devoted to exploring the intermediate avenues through which neoliberal ideas travel from global governance institutions to national governance contexts. This article aims to address this gap in the study of contemporary global governance and neoliberal policy diffusion through critically examining the evolving role of the Joint Vienna Institute (JVI), an international training organisation set up after the end of the Cold War to transmit global ‘best practice’ economic policy ideas to national officials in post-communist economies.
Coefficient of normal restitution of viscous particles and cooling rate of granular gases
We investigate the cooling rate of a gas of inelastically interacting
particles. When we assume velocity dependent coefficients of restitution the
material cools down slower than with constant restitution. This behavior might
have large influence to clustering and structure formation processes.Comment: 3 figures, Phys. Rev. E (in press
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